Patent Grant
11701765
This application is based upon and claims the benefit of priority from prior Japanese patent application No. 2020-113614, filed on Jun. 30, 2020, the entire contents of which are incorporated herein by reference.
The present disclosure relates to a pneumatic tool that operates using compressed air as a power source.
A pneumatic tool called a nailing machine is known in which a striking piston is reciprocated using compressed air as a power source to drive a driver coupled to the striking piston and strike a nail or the like supplied to a nose. Such a nailing machine is configured to strike a nail by operating a main valve with two operations, that is, one operation of pulling a trigger provided on a grip portion and another operation of pressing a contact arm that protrudes from a tip of the nose and can be reciprocated against a member to be driven.
In the following description, the state in which the trigger is pulled by one operation is referred to as ON of the trigger, and the state in which one operation is released and the trigger is not pulled is referred to as OFF of the trigger. Further, the state in which the contact arm is pressed by another operation is referred to as ON of the contact arm, and the state in which another operation is released and the contact arm is not pressed is referred to as OFF of the contact arm.
In the nailing machine, for example, the main valve is operated by turning on the trigger and then turning on the contract arm with the trigger turned on, thereby striking a nail.
A technique has been proposed in which, after striking a nail, a main valve is operated by turning off a contact arm with a trigger turned on and turning on the contact arm again with the trigger turned on, thereby striking next nail. In this way, an operation of continuously striking a nail by repeating ON and OFF of the contact arm with the trigger turned on is referred to as contact striking.
In the contact striking, after striking a nail, a nail can be continuously struck every time the contact arm is turned on with the trigger turned on, which is suitable for quick work. On the other hand, in order to regulate careless operation, a technique has been proposed in which the main valve is deactivated when a predetermined time has elapsed without turning on the contact arm after the trigger is turned on (e.g., see PTL 1).
PTL 1: Japanese Examined Utility-Model Publication No. H6-32308
In the configuration in which the main valve is deactivated when a predetermined time has elapsed without turning on the contact arm after the trigger is turned on, the timekeeping can be stably performed by measuring a lapse of a predetermined time using an electric timer. However, nailing machines driven by compressed air do not include a source of electricity. Therefore, a power supply and a circuit are required in order to use an electric timer.
On the other hand, PTL 1 proposes a timekeeping mechanism that uses the pressure of compressed air in a main chamber to store compressed air for operating a nailing machine. For example, the timekeeping mechanism using the air pressure has a configuration in which compressed air is supplied from a main chamber to a space of a predetermined volume and the main valve is operated by the air pressure when the pressure in the space reaches a predetermined pressure.
Such a timekeeping mechanism does not require a power supply and a circuit. However, since the pressure in the main chamber fluctuates due to the fact that the pressure of compressed air supplied from a compressor and the like (not shown) is not always constant and that the compressed air in the main chamber is consumed in a nail striking operation and the like, the time until the pressure in the space reaches a predetermined pressure to operate the main valve is not constant. Therefore, in the nailing machine to which the timekeeping mechanism using air pressure is applied, it is difficult to stably perform the timekeeping, and the time from when the trigger is pulled until the main valve is deactivated is not constant.
Therefore, a timekeeping mechanism has been proposed in which air is compressed in a nailing machine and the pressure of the compressed air is used. With such a timekeeping mechanism, the influence of pressure fluctuation in the main chamber can be eliminated. However, the variation of pails affects the timekeeping, and it is not possible to eliminate the variation in timekeeping caused by the variation of parts.
The present disclosure has been made to solve the above problem and an object thereof is to provide a pneumatic tool capable of eliminating the variation in timekeeping.
According to an aspect of the present invention, there is provided a pneumatic tool including: a drive part configured to be driven by compressed air; a control valve configured to switch the presence or absence of operation of the drive part; an on-off valve part configured to switch the presence or absence of operation of the control valve; and a timer part configured to control the operation of the on-off valve part and switch the presence or absence of operation of the control valve after a lapse of a predetermined time, wherein the timer part includes a timer piston configured to move in one direction and perform timekeeping, and a timer piston cylinder configured to support the timer piston such that the timer piston can slide, wherein the pneumatic tool includes a throttle part configured to throttle the flow rate of air flowing into or flowing out from the timer piston cylinder, and an adjustment part configured to adjust an operating time of the timer piston.
In the present disclosure, the variation in timekeeping for each machine is eliminated by adjusting the operating time of the timer piston with the adjustment part.
In the present disclosure, the variation in timekeeping for each machine caused by the variation and the like of parts is eliminated, so that it is possible to make the timing of switching the presence or absence of operation of the object to be controlled constant.
Hereinafter, a nailing machine as a striking tool, which is an example of a pneumatic tool of the present disclosure, will be described with reference to the drawings.
<Configuration Example of a Nailing Machine of a First Embodiment>
A nailing machine 1A of the first embodiment incudes a housing 10 having a shape extending in one direction and a handle 11 having a shape extending in the other direction from the housing 10. Further, the nailing machine 1A includes a nose 12 at one end of the housing 10 and a magazine 13 that supplies a nail (not shown) to the nose 12. Considering the usage pattern of the nailing machine 1A, the side where the nose 12 is provided is defined as the lower side.
The nailing machine 1A includes a striking cylinder 2 that operates with compressed air to perform a striking operation and a main chamber 3 to which compressed air is supplied from an external air compressor (not shown).
The striking cylinder 2 is an example of a drive part and is provided inside the housing 10 so as to extend in an upper and lower direction. The striking cylinder 2 includes a striking driver 20 for striking out a nail or the like (not shown), and a striking piston 21 for driving the striking driver 20. The striking driver 20 is attached to the striking piston 21 so as to protrude from a lower surface side of the striking piston 21. The striking piston 21 is provided with an O-ring 21a as a sealing member on the outer periphery thereof and is slidably attached to the inside of the striking cylinder 2.
In the striking cylinder 2, the striking piston 21 is pressed by the compressed air supplied from the main chamber 3, and the striking piston 21 and the striking driver 20 are integrally moved, so that the striking driver 20 is driven by the striking piston 21. The striking driver 20 driven by the striking piston 21 is guided by the nose 12 to strike out a nail (not shown) supplied from the magazine 13 to the nose 12.
The main chamber 3 is provide inside the handle 11. Compressed air is supplied from an air compressor into the main chamber 3 by connecting a hose (not shown) to a chuck 30 provided at an end of the handle 11. Further, an end cap filter 30a for suppressing foreign matters from entering the main chamber 3 is provided between the chuck 30 and the main chamber 3.
The nailing machine 1A includes a blowback chamber 31 to which compressed air for returning the striking piston 21 after the striking operation is supplied. The blowback chamber 31 is provided around a lower portion of the striking cylinder 2 in the housing 10. The blowback chamber 31 is connected to the striking cylinder 2 via an inflow/discharge port 31a provided at a substantially intermediate portion in the upper and lower direction of the striking cylinder 2, and compressed air is supplied to the blowback chamber 31 via the main chamber 3 and the striking cylinder 2. The inflow/discharge port 31a includes a check valve 31b that regulates the direction in which air flows in one direction. The check valve 31b allows air to flow from the striking cylinder 2 to the blowback chamber 31 and regulates the backflow of air from the blowback chamber 31 to the striking cylinder 2.
The nailing machine 1A includes a first air flow path 32 that forms a flow path communicating with the atmosphere.
The nailing machine 1A includes a main valve 4 that switches the inflow/outflow of compressed air in the main chamber 3 to reciprocate the striking piston 21, and a trigger valve 5 that operates the main valve 4.
The main valve 4 is an example of a valve mechanism. The main valve 4 reciprocates the striking piston 21 by switching between the inflow of compressed air from the main chamber 3 into the striking cylinder 2 and the outflow of compressed air from the striking cylinder 2 to the outside.
The main valve 4 is provided on an outer peripheral side of an upper end portion of the striking cylinder 2 so as to be vertically movable. Further, the main valve 4 is urged upward in a closing direction by the force of a main valve spring 41. Furthermore, the main valve 4 is pushed upward by the air pressure of compressed air when compressed air is supplied from the main chamber 3 to a main valve lower chamber 42 via the trigger valve 5. Further, the main valve 4 is pushed downward by the air pressure of compressed air when compressed air is supplied from the main chamber 3 to a main valve upper chamber 43.
In this way, when the main valve 4 is not operating, the main valve 4 is urged upward and located at a top dead center position due to the relationship between the balance of the air pressure of compressed air supplied into the main valve lower chamber 42 and the air pressure of compressed air supplied into the main valve upper chamber 43 and the force of the main valve spring 41, and a top opening portion 44 of the main chamber 3 and the striking cylinder 2 is blocked. Further, when the main valve 4 is operating, the main valve lower chamber 42 communicates with the atmosphere. Thus, the main valve 4 is pushed downward by the air pressure of compressed air supplied into the main valve upper chamber 43, and the top opening portion 44 of the main chamber 3 and the striking cylinder 2 is opened.
The trigger valve 5 is an example of a control valve. The trigger valve 5 includes a pilot valve 50 that opens and closes the main valve lower chamber 42, and a trigger valve housing 51 to which the pilot valve 50 is attached so as to be vertically movable. Further, the trigger valve 5 includes a trigger valve stem 52 that operates the pilot valve 50, a trigger valve cap 53 to which the trigger valve stem 52 is attached so as to be vertically movable, and a trigger valve stem spring 54 that urges the pilot valve 50 upward and urges the trigger valve stem 52 downward.
Compressed air is supplied to the trigger valve 5 from the main chamber 3, and the pilot valve 50 is pushed downward by the air pressure of the compressed air. Further, in the trigger valve 5, compressed air is supplied to a trigger valve lower chamber 55 formed between the pilot valve 50 and the trigger valve cap 53, and the pilot valve 50 is pushed upward by the air pressure of the compressed air.
In this way, the pilot valve 50 is held at an upper position due to the relationship between the balance of the air pressure of the compressed air and the force of the trigger valve stem spring 54. Further, in the trigger valve 5, the trigger valve lower chamber 55 communicates with the atmosphere according to the position of the trigger valve stem 52, and the pilot valve 50 is moved downward by the air pressure of the compressed air. When the pilot valve 50 is moved downward, a passage through which the first air flow path 32 communicates with the atmosphere is opened, and the main valve lower chamber 42 communicates with the atmosphere.
The trigger valve 5 includes a timer switch 56 that operates a timer (to be described later), timer switch housings 57A to 57C to which the timer switch 56 is attached so as to be vertically movable, a timer switch cap 58 to which the timer switch 56 is attached so as to be vertically movable and which supports the timer switch housings 57A to 57C, and a timer switch spring 59 that urges the timer switch 56 downward.
In the trigger valve 5, a gap between the timer switch cap 58 and the timer switch housing 57C forms a flow path through which air passes in communication with a first timer operating flow path 33a connected to the blowback chamber 31. Further, in the trigger valve 5, a gap between the timer switch housing 57C and the timer switch housing 57B forms a flow path through which air passes in communication with a second timer operating flow path 33b connected to the timer (to be described later). Furthermore, in the trigger valve 5, a gap between the trigger valve housing 57A and the trigger valve housing 57B forms a flow path through which air passes in communication with the main chamber 3. Further, a flow path forming recess 56a having a concave outer peripheral surface along a circumferential direction is formed in the timer switch 56.
The timer switch 56 switches the presence and absence of communication between the first timer operating flow path 33a and the second timer operating flow path 33b according to the position of the flow path forming recess 56a with respect to the timer switch housings 57A to 57C and the timer switch cap 58.
Further, in the trigger valve 5, a gap between the timer switch housing 57A and the trigger valve cap 53 forms a flow path that communicates an operation regulating flow path 34 connected to the main chamber 3 via the timer (to be described later) and the trigger valve lower chamber 55.
The nailing machine 1A includes a trigger 6 that receives one operation for operating the trigger valve 5, and a contact arm 7 that receives another operation for operating the trigger valve 5.
The trigger 6 is provided on one side of the handle 11. The trigger 6 is configured such that one end side near the housing 10 is rotatably supported by a shaft 60a and the other end side farther from the housing 10 is urged by a trigger spring 60b in the direction away from the handle 11.
The trigger 6 includes a contact lever 70 that is pushed by the contact arm 7. One end side of the contact lever 70 near the housing 10 extends to a position facing the trigger valve stem 52. The contact lever 70 includes an acting portion 70a for pushing the trigger valve stem 52 on the one end side thereof. Further, the other end side of the contact lever 70 is rotatably supported on the trigger 6 by a shaft 70b. Furthermore, the contact lever 70 is urged by a spring (not shown) in the direction in which the acting portion 70a is separated from the trigger valve stem 52.
The trigger 6 includes a timer switch lever 61 that pushes the timer switch 56. The timer switch lever 61 rotates in conjunction with the rotation of the trigger 6 with the shaft 60a as a fulcrum, and pushes the timer switch 56 by an operation in which the other end side of the trigger 6 is moved in the direction approaching the handle 11.
The contact arm 7 is provided so as to be movable along an extending direction of the nose 12. The contact arm 7 includes a butting portion 71 that is butted against a member to be driven on the tip end side of the nose 12. Further, the contact arm 7 includes a pressing portion 72 that pushes an acted portion 70c of the contact lever 70. The contact arm 7 is urged by a contact arm spring 73 in the direction protruding from the tip end side of the nose 12.
The nailing machine 1A includes a timer 8 that performs a timekeeping operation. The timer 8 is an example of a timer part. The timer 8 includes a timer piston 80 that generates compressed air for timekeeping as a load, a timer piston spring 81 that urges the timer piston 80, and a timer piston spring guide 81a that guides the expansion and contraction of the timer piston spring 81. The timer 8 performs a meter-out control in which the speed of the timer piston 80 is controlled by adjusting the amount of outflow air from a timer piston cylinder 80d.
Further, the timer 8 includes timer piston housings 82A to 82F that movably support the timer piston 80 and form a flow path through which air passes. Furthermore, the timer 8 includes a preset piston 83 that operates the timer piston 80, a preset piston spring 84 that urges the preset piston 83, and a preset piston housing 85 that movable supports the preset piston 83.
The timer 8 is configured such that the timer piston 80 and the preset piston 83 can move along the extending direction of the handle 11. The timer 8 is configured such that the timer piston housings 82A to 82F are arranged along the extending direction of the handle 11, the timer piston housing 82F constituting the timer piston cylinder 80d movably supports the timer piston 80, and the timer piston housings 82A to 82E movably support a timer piston shaft 86 that is the shaft part of the timer piston 80.
A Y-ring 80a that has a Y-shaped cross section as a sealing member having a lip structure is fitted to the outer periphery of the timer piston 80. The Y-ring 80a slides on an inner peripheral surface of the timer piston cylinder 80d.
The timer 8 is configured such that the cylindrical timer piston housing 82C is inserted inside the timer piston housing 82B and the timer piston housing 82D, and the timer piston shaft 86 passes through the inside of the timer piston housing 82C.
Further, in the timer 8, a gap between the timer piston housing 82B and the timer piston housing 82D communicates with an inflow flow path 35 connected to the main chamber 3 to form a flow path through which air passes. Further, in the timer 8, a gap between the timer piston housing 82B and the timer piston housing 82D, a gap between the timer piston housing 82B and the timer piston housing 82C, and a gap between the timer piston housing 82B and the timer piston housing 82A communicate the inflow flow path 35 and the operation regulating flow path 34 with each other to form a flow path through which air passes.
In the timer piston 80, a flow path forming recess 87b having a concave shape along the circumferential direction is formed in the vicinity of substantially the center of the timer piston shaft 86 in an axial direction.
In the timer 8, a flow path communicating the inflow flow path 35 and the operation regulating flow path 34 with each other is closed by an O-ring 87a in a state where the O-ring 87a provided on the timer piston housing 82B is in contact with the timer piston shaft 86. On the contrary, in the timer 8, the flow path communicating the inflow flow path 35 and the operation regulating flow path 34 with each other is opened by a gap between the O-ring 87a and the flow path forming recess 87b when the timer piston 80 is moved to a position where the flow path forming recess 87b faces the O-ring 87a. In this way, the O-ring 87a, the timer piston shaft 86 and the flow path forming recess 87b constitute an on-off valve part 87 that opens and closes the flow path communicating the inflow flow path 35 and the operation regulating flow path 34 with each other.
The timer piston shaft 86 constituting a shaft part of the on-off valve part 87 is formed such that the diameter of a shaft portion 86b on the side opposite to the timer piston 80 is larger than the diameter of a shaft portion 86a on the side of the timer piston 80 with the flow path forming recess 87b interposed therebetween. In the timer piston shaft 86, a pressure receiving surface 87H that receives the force of the compressed air supplied from the main chamber 3 is formed by the diameter difference of the timer piston shaft 86, which is the difference between the diameter of the shaft portion 86a and the diameter of the shaft portion 86b. In this way, the timer piston shaft 86 constituting the on-off valve part 87 is pressed by the supply pressure.
The preset piston 83 is provided coaxially with the timer piston 80. The preset piston housing 85 is connected to the blowback chamber 31 via the second timer operating flow path 33b, the timer switch 56, the timer switch housings 57B, 57C, the timer switch cap 58, and the first timer operating flow path 33a.
The timer 8 includes a discharge flow path 88 that communicates the preset piston housing 85 with the atmosphere. The timer 8 is configured such that the air in the preset piston housing 85 is discharged to the outside from the discharge flow path 88 by the operation of moving the preset piston 83.
Further, the opening and closing of a flow path formed between the timer piston housing 82A and the timer piston shaft 86 and a flow path formed between the preset piston housing 85 and a preset piston shaft 83a are switched according to the position of the timer piston 80.
When the flow path formed between the timer piston housing 82A and the timer piston shaft 86 communicates with the flow path formed between the preset piston housing 85 and the preset piston shaft 83a, the operation regulating flow path 34, the flow path formed by the timer piston housing 82A and the flow path formed by the preset piston housing 85 communicate with the discharge flow path 88.
Furthermore, the opening and closing of the trigger valve lower chamber 55 and the operation regulating flow path 34 are switched according to the position of the trigger valve stem 52. When the trigger valve lower chamber 55 communicates with the operation regulating flow path 34, the trigger valve lower chamber 55 communicates with the atmosphere via the operation regulating flow path 34, the flow path formed by the timer piston housing 82A, the flow path formed by the preset piston housing 85, and the discharge flow path 88.
The nailing machine 1A includes a choke 9. The choke 9 is an example of a throttle part. The choke 9 includes a discharge flow path 90 communicating with the timer piston housing 82F, a filter 91 provided in the discharge flow path 90, and a needle 92 for throttling the discharge flow path 90.
Further, the nailing machine 1A includes a foreign matter discharge flow path 93 that suppresses foreign matters from entering the choke 9 mainly from the flow path formed between the timer piston housings 82A to 82C and the timer piston shaft 86. The foreign matter discharge flow path 93 communicates the flow path formed between the timer piston housing 82D and the timer piston shaft 86 with the atmosphere.
<Operation Example of the Nailing Machine of the First Embodiment>
Next, the operation of the nailing machine 1A of the first embodiment will be described with reference to each drawing.
In this way, the main chamber 3, the main valve lower chamber 42, the main valve upper chamber 43, and the trigger valve lower chamber 55 have atmospheric pressure. Thus, the main valve 4 is urged by the main valve spring 41 and located in the top dead center position. Further, in the trigger valve 5, the pilot valve 50 is urged by the trigger valve stem spring 54 and held in the upper position. The position of the pilot valve 50 shown in
When the timer switch 56 of the trigger valve 5 is in the non-operating position, the main chamber 3 communicates with the second timer operating flow path 33b. Since a hose from an air compressor (not shown) is not connected to the chuck 30, the main chamber 3 is in a state of communicating with the atmosphere. In this way, in the timer 8, the preset piston 83 is urged by the preset piston spring 84 and held in the left position. The position of the preset piston 83 shown in
In this way, the main chamber 3, the main valve lower chamber 42, the main valve upper chamber 43, and the trigger valve lower chamber 55 have a pressure corresponding to the supply pressure of compressed air. Hereinafter, the pressure corresponding to the supply pressure of compressed air is referred to as the supply pressure. Therefore, the main valve 4 is held in the top dead center position. Further, in the trigger valve 5, the pilot valve 50 is held in the non-operating position. Furthermore, in the trigger valve 5, the trigger valve stem 52 is held in the non-operating position. Further, in the trigger valve 5, the timer switch 56 is held in the non-operating position in a state where the trigger 6 does not operate.
When the timer switch 56 of the trigger valve 5 is in the non-operating position, the main chamber 3 communicates with the second timer operating flow path 33b. When a hose from an air compressor (not shown) is connected to the chuck 30, the main chamber 3 has the supply pressure. In this way, in the timer 8, the preset piston 83 is pushed by the air pressure corresponding to the supply pressure and is moved to the right position. The position of the preset piston 83 shown in
When the timer switch 56 of the trigger valve 5 is in the operating position, the first timer operating flow path 33a and the second timer operating flow path 33b communicates with each other. The blowback chamber 31 communicates with the atmosphere. In this way, in the timer 8, the preset piston 83 is urged by the preset piston spring 84 and starts to advance from the timekeeping start position. Further, in the timer 8, the timer piston 80 is urged by the timer piston spring 81 and starts to advance from the timekeeping start position.
Even if the trigger 6 is operated, the contact lever 70 does not push the trigger valve stem 52 in a state where the butting portion 71 of the contact arm 7 is not butted against a member to be driven.
A preset piston front chamber 83a formed by moving the preset piston 83 to the operating position communicates with the blowback chamber 31 via the first timer operating flow path 33a and the second timer operating flow path 33b. These flow paths do not become a large load when discharging the air in the preset piston front chamber 83a. In this way, the preset piston 83 is moved to the non-operating position in a very short time after the operation of the trigger 6.
On the contrary, a timer piston front chamber 80c, which is a chamber formed by moving the timer piston 80 to the operating position, communicates with the atmosphere via the choke 9. When the throttle of the choke 9 is narrowed to the point where only a very small amount of air flows, the timer piston front chamber 80c can be regarded as being substantially sealed at the moment when the timer piston 80 is moved. Thus, the volume of the timer piston front chamber 80c is reduced by the amount of movement of the timer piston 80, and the pressure is increased by that amount. The timer piston front chamber 80c is not configured to be supplied with compressed air from the main chamber 3. The internal pressure of the timer piston front chamber 80c is determined according to the position of the timer piston 80. In this way, the pressure in the timer piston front chamber 80c is not affected by the supply pressure. When the spring force of the timer piston spring 81 and the surface pressure of the air pressure due to internal compression are balanced, the timer piston 80 can advance by the amount of air released via the choke 9 from that time.
The timer piston 80 advances in a shorter time up to a predetermined position where the pressure in the timer piston front chamber 80c rises to a certain degree, as compared with the time from 0 seconds from the operation of the trigger to the end of timekeeping. Further, from the predetermined position where the pressure in the timer piston front chamber 80c rises to a certain degree to the non-operating position, the timer piston 80 is moved at a lower speed with respect to the moving speed up to the predetermined position where the pressure in the timer piston front chamber 80c rises to a certain degree.
From 0 seconds from the operation of the trigger to the end of timekeeping, that is, during the period in which the timer piston 80 starts to advance from the timekeeping start position and is moved to the non-operating position, the pressing portion 72 of the contact arm 7 pushes the contact lever 70 when the contact arm 7 shown in
When the trigger 6 is moved to the operated position, the acting portion 70a of the contact lever 70 pushes the trigger valve stem 52. In the trigger valve 5, the flow path communicating the trigger valve lower chamber 55 with the main chamber 3 is closed and the flow path communicating the trigger valve lower chamber 55 with the operation regulating, flow path 34 is opened when the trigger valve stem 52 is moved upward by a predetermined amount.
Further, while the timer piston 80 is moved from the timekeeping start position to the non-operating position, the flow path formed between the timer piston housing 82A and the timer piston shaft 86 and the flow path formed between the preset piston housing 85 and the preset piston shaft 83a communicate with each other.
In this way, the trigger valve lower chamber 55 communicates with the atmosphere via the operation regulating flow path 34, the flow path formed by the timer piston housing 82A, the flow path formed by the preset piston housing 85 and the discharge flow path 88, and compressed air is discharged therefrom, so that the air pressure in the trigger valve lower chamber 55 decreases.
Therefore, a force that pushes the pilot valve 50 downward with the air pressure of compressed air supplied from the main chamber 3 becomes larger than the force of the trigger valve stem spring 54. Then, the pilot valve 50 is moved downward, and the first air flow path 32 is opened.
When the first air flow path 32 is opened, the main valve lower chamber 42 is shut off from the main chamber 3 and communicates with the atmosphere. Then, compressed air is discharged from the main valve lower chamber 42, and the air pressure in the main valve lower chamber 42 decreases. In this way, a force that pushes the main valve 4 downward with the air pressure of compressed air supplied from the main chamber 3 into the main valve upper chamber 43 becomes larger than the force of the main valve spring 41. Then, the main valve 4 is moved downward, and the top opening portion 44 is opened. Therefore, the compressed air in the main chamber 3 is supplied to the striking cylinder 2.
In this way, the striking cylinder 2 is operated by the compressed air, the striking piston 21 is moved in the direction of striking out a nail (not shown), and the striking driver 20 performs a striking operation. Further, a part of the compressed air in the striking cylinder 2 is supplied from the inflow/discharge port 31a to the blowback chamber 31.
When the trigger 6 is moved to the operated position during the striking operation, the timer switch 56 is moved to the operating position, and the first timer operating flow path 33a and the second timer operating flow path 33b communicate with each other. Further, during the striking operation, a part of the compressed air in the striking cylinder 2 is supplied from the inflow/discharge port 31a to the blow back chamber 31. In this way, in the timer 8, the preset piston 83 is pushed by the air pressure corresponding to the supply pressure of the compressed air and is moved to the timekeeping start position. Further, in the timer 8, the timer piston 80 is pushed by the preset piston 83 and is moved to the timekeeping start position. The operation in which the timer piston 80 is moved to the timekeeping start position by the striking operation is referred to as the reset of the timer 8.
After the striking operation, compressed air is supplied from the blowback chamber 31 to the striking cylinder 2, the striking piston 21 is moved in the direction of returning the striking driver 20, and the striking piston 21 returns to the top dead center position. When the striking piston 21 returns to the top dead center position, the blowback chamber 31 is in a state of communicating with the atmosphere.
In this way, in the timer 8 after being reset, the preset piston 83 is urged by the preset piston spring 84 and starts to advance from the timekeeping start position. Further, in the timer 8, the timer piston 80 is urged by the timer piston spring 81 and starts to advance from the timekeeping start position. Therefore, the timekeeping is initiated as described with reference to
When the contact arm 7 is not pressed against the member to be driven and the trigger valve stem 52 is not pushed by the contact lever 70 for a predetermined time after the start of timekeeping described with reference to
In the timer 8, the flow path forming recess 87b of the timer piston shaft 86 is moved to a position facing the O-ring 87a when the timer piston 80 is moved to the non-operating position. In this way, the flow path communicating the inflow flow path 35 with the operation regulating low path 34 is opened by the gap between the O-ring 87a and the flow path forming recess 87b, and compressed air is supplied from the main chamber 3 to the operation regulating flow path 34.
When the contact arm 7 shown in
When the trigger 6 is moved to the operated position, the acting portion 70a of the contact lever 70 pushes the trigger valve stem 52. In the trigger valve 5, the trigger valve lower chamber 55 communicates with the operation regulating flow path 34 when the trigger valve stem 52 is moved upward by a predetermined amount. When the timer piston 80 is moved to the non-operating position, compressed air is supplied from the main chamber 3 to the operation regulating flow path 34. In this way, the trigger valve lower chamber 55 has a supply pressure by compressed air supplied from the main chamber 3 via the operation regulating flow path 34.
Therefore, the pilot valve 50 is held in the upper position due to the relationship between the balance of the air pressure of compressed air and the force of the trigger valve stem spring 54. In this way, the first air flow path 32 is not opened, the main valve 4 is held at the top dead center position, and the striking cylinder 2 does not operate.
<Detailed Example of the Timer and the Choke>
In the nailing machine 1A, until the timer piston 80 is moved from the timekeeping start position to the non-operating position after the trigger 6 is operated, the contact arm 7 is pressed against the member to be driven to perform the striking operation, and the timer 8 is reset.
On the other hand, when the timer piston 80 is moved from the timekeeping start position to the non-operating position after the trigger 6 is operated, the nailing machine 1A becomes a time-out, and the striking operation is not performed even when the contact arm 7 is pressed against the member to be driven.
In the nailing machine 1A, the moving speed of the timer piston 80 is controlled by generating compressed air by the timer 8 and the choke 9. In the timer 8, the time until the time-out is set by the balance among the force urging the timer piston 80 by the timer piston spring 81, the surface pressure of the air pressure applied to the timer piston 80, the sliding resistance of the timer piston 80 and the timer piston housing 82F, and the sliding resistance of the timer piston shaft 86 and the timer piston housings 82A to 82E.
Contact surface pressure is generated in an O-ring as a sealing member used in the trigger valve 5 and the timer 8 by the crushing margin at the time of assembly. When air pressure is applied to the timer piston 80, the surface contact pressure increases and the sliding resistance increases as the pressure increases. Under the influence of the environment, the rigidity of rubber increases at a lower temperature, and the sliding resistance further increases when the coefficient of friction increases due to running out of oil. These factors synergistically act and the sliding resistance changes, which greatly affects the time until the time-out.
On the other hand, reducing this change in sliding resistance leads to reducing the time-out time difference.
Therefore, the coefficient of friction of each sliding surface is reduced for the purpose of reducing the sliding resistance. At that time, it has been found that the desire purpose of reducing the sliding resistance can be achieved by using a material with a small friction resistance for a specific part and performing surface treatment.
First, the timer piston housing 82F on which the timer piston 80 slides is surface-treated with hard chrome plating. Further, among the timer piston housings 82A to 82E on which the timer piston shaft 86 slides, the timer piston housing 82C, which can come into contact with the timer piston shaft 86 without using a sealing member and has a large contactable area, is made of a high sliding grade POM.
Furthermore, the Y-ring 80a is used instead of an O-ring as a sealing member for the timer piston 80 that slides on the timer piston housing 82F. The Y-ring 80a having a Y-shaped cross section has a smaller sliding resistance than the O-ring when low-pressure air is shut off, and can suppress an increase in sliding resistance at a lower temperature.
The timer piston front chamber 80c formed by moving the timer piston 80 to the timekeeping start position is not configured to be supplied with compressed air from the main chamber 3, and the internal pressure thereof is determined according to the position of the timer piston 80. Therefore, the pressure in the timer piston front chamber 80c is lower than the supply pressure in the main chamber 3.
In this way, the necessary and sufficient blocking property can be obtained by using the Y-ring 80a instead of the O-ring as the sealing member for the timer piston 80. The variation in the time-out time can be suppressed by the characteristic of the Y-ring that the sliding resistance is smaller than that of the O-ring and the characteristic of the Y-ring that the increase in sliding resistance at a lower temperature can be suppressed.
The timer piston front chamber 80c is not configured to be supplied with compressed air from the main chamber 3, and the Y-ring 80a can be used for the timer piston 80. On the other hand, since a gap between the timer piston housing 82A and the timer piston shaft 86 and a gap between the timer piston housings 82B to 82D and the timer piston shaft 86 serve as a flow path for supplying compressed air from the main chamber 3, the air pressure in these portions is higher than that of the timer piston front chamber 80c. Therefore, it is not suitable to use the Y-ring as the sealing member in these portions, and the O-ring 87a is used in the on-off valve part 87 and the like.
As described above, contact surface pressure is generated in the O-ring by the crushing margin at the time of assembly. When air pressure is applied to the timer piston 80, the surface contact pressure increases and the sliding resistance increases as the pressure increases. Under the influence of the environment, the rigidity of rubber increases at a lower temperature, and the sliding resistance further increases when the coefficient of friction increases due to running out of oil. These factors synergistically act and the sliding resistance changes, which greatly affects the time until the time-out. In this way, the sliding resistance of the on-off valve part 87 and the like using the O-ring as the sealing member becomes large due to the influence of the supply pressure, which affects the time until the time-out. Therefore, a force that cancels the sliding resistance by using the supply pressure is applied to the timer piston 80.
In the configuration in which the pressure receiving surface 87H formed by the diameter difference of the timer piston shaft 86 generates the force for pushing the timer piston shaft 86 in the axial direction by the supply pressure, similarly to the sliding resistance, the force for pushing the timer piston shaft 86 also increases as the supply pressure increases.
Therefore, the force for pushing the timer piston shaft 86 in the axial direction by the supply pressure is generated in the direction of cancelling the sliding resistance. Since the timer piston shaft 86 is moved in an arrow F1 direction by the timekeeping operation in which the timer piston 80 is moved from the timekeeping start position to the non-operating position, sliding resistance in an arrow F2 direction opposite to the moving direction is generated. On the other hand, when the diameter of the shaft portion 86b on the side opposite to the timer piston 80 is made larger than the diameter of the shaft portion 86a on the side of the timer piston 80 with the flow path forming recess 87b interposed therebetween, a force for pushing the timer piston shaft 86 is generated in an arrow F3 direction along the moving direction of the timer piston shaft 86 in the timekeeping operation.
In this way, even when the sliding resistance between the timer piston shaft 86 and the O-ring 87a increases in proportional to the supply pressure, similarly, the force for pushing the timer piston shaft 86 in the axial direction also increases due to the difference in the pressure receiving area, and therefore, the change in sliding resistance can be cancelled.
In this manner, the variation in the time-out time can be suppressed as necessary and sufficient by a combination of material change and surface treatment of a specific part in the timer piston housings 82A to 82F, using the Y-ring 80a for the timer piston 80, and cancelling the change in sliding resistance by using the difference in the pressure receiving area. The Y-ring has a characteristic that the sliding resistance is small at a low pressure, but the sliding resistance increases sharply as the pressure increases. On the contrary, the pressure in the timer piston front chamber 80c is smaller than the supply pressure in the main chamber 3, as described above. In this way, when the Y-ring 80a is used for the timer piston 80 on which the air pressure lower than the supply pressure acts, the demerit at the time of using the Y-ring as the sealing member, that is, the demerit that the sliding resistance increases when a high pressure such as the supply pressure is applied is suppressed, and the merit that the sliding resistance is small at a low pressure can be utilized.
Subsequently, a configuration for reliably opening and closing the on-off valve part 87 will be described. The on-off valve part 87 has a flow path that is opened by the gap between the O-ring 87a and the flow path forming recess 87b when the flow path forming recess 87b is moved to a position facing the O-ring 87a. However, the on-off valve part 87 may be not opened under a high temperature or a high pressure due to fluctuation in the supply pressure.
The reason is considered to be that the rigidity of the O-ring, which is a rubber part, decreases at a high temperature or the amount of deformation of the O-ring increases at a high pressure, and thus, the O-ring 87a is deformed to be continuously in contact with the flow path forming recess 87b.
Therefore, the on-off valve part 87 includes a deformation suppressing portion 87c for the O-ring 87a. The on-off valve part 87 is a groove formed between the timer piston housing 82B and the timer piston housing 82C along the axial direction of the timer piston shaft 86, and a mounting groove portion 87d for the O-ring 87a is formed therein. Further, the deformation of the O-ring 87a is suppressed by narrowing the opening on the entrance side of the mounting groove portion 87d facing the timer piston shaft 86 along the axial direction of the timer piston shaft 86.
In this way, as shown in
In this way, as shown in
Subsequently, the accuracy improvement of the timer piston housing composed of a plurality of parts will be described.
Therefore, the sliding surface on which the timer piston 80 and the timer piston shaft 86 slide is configured by the inner wall surfaces of the plurality of timer piston housings 82A to 82F. When the central axes of the inner wall surfaces of the plurality of timer piston housings 82A to 82F are deviated from each other, this causes a delay in the time-out time due to excessive interference of any one of the timer piston housings with the timer piston 80 and the timer piston shaft 86, and this also causes a stable time-out time not to be obtained.
For this reason, the spaces between the plurality of timer piston housings are supported by a plurality of ribs 89 provided on inner wall surfaces or outer wall surfaces of the timer piston housings 82A to 82F. In the configuration in which the ribs 89 are provided on the inner wall surfaces of the timer piston housings, a diameter of a virtual circle connecting tips of the ribs 89 is made smaller than an outer diameter of the outer wall surface of the timer piston housing to be fitted, thereby providing a crushing margin. Further, in the configuration in which the ribs 89 are provided on the outer wall surfaces of the timer piston housings, the diameter of the virtual circle connecting the tips of the ribs 89 is made larger than an outer diameter of the inner wall surface of the timer piston housing to be fitted, thereby providing a crushing margin.
As shown in
As shown in
The timer piston housings 82A to 82F can form the timer piston housing assembly 82G having substantially the same central axis, so that excessive interference of any one of the timer piston housings with the timer piston 80 and the timer piston shaft 86 is suppressed and a stable time-out time is obtained. Further, gaps are formed between the outer wall surfaces and the inner wall surfaces of the fitting portions of the timer piston housings 82A to 82F by the ribs 89, and these gaps form a flow path 89F, through which air or oil passes.
As described above, since the timer piston housings 82A to 82F can form the timer piston housing assembly 82G having substantially the same central axis, the clearance between the timer piston housings 82A to 82F and the timer piston 80 and the timer piston shaft 86 can be reduced. Radial fluctuation of the timer piston shaft 86 is suppressed and the behavior is stabilized when the clearance is reduced. On the other hand, the influence of the presence or absence of lubricating oil and the changes in the viscous resistance of lubricating oil due to temperature environment becomes lamer.
Therefore, among the timer piston housings 82A to 82E on which the timer piston shaft 86 slides, the timer piston housing 82C, which can come into contact with the timer piston shaft 86 without using a sealing member and has a large contactable area, is provided with a flow path expansion groove 82C2 on a guide surface 82C1 into which the timer piston shaft 86 is inserted.
The flow path expansion groove 82C2 is configured by providing grooves extending along the axial direction of the timer piston shaft 86 at a plurality of locations in the circumferential direction of the guide surface 82C1. In this way, at the position of the timer piston housing 82C where the flow path expansion groove 82C2 is not formed, the clearance between the timer piston shaft 86 and the guide surface 82C1 can be maintained, and the guide property of the timer piston shaft 86 can be maintained. Further, at the position of the timer piston housing 82C where the flow path expansion groove 82C2 is formed, the flow path of lubricating oil is expanded and the viscous resistance can be reduced. In this way, the influence of the change in the viscous resistance of oil on the time-out time can be suppressed.
Subsequently, the performance maintenance of the choke 9 will be described. The choke 9 has a configuration in which the needle 92 is inserted into a tubular flow path and the discharge flow path 90 is throttled. Since the throttled flow path is extremely narrow, the time-out time may be significantly delayed when foreign matters such as oil are introduced. Even when the flow path communicating with the choke 9 is shut off from the main chamber 3 by sealing the space between each timer piston housing and the timer piston with the O-ring, a very small amount of oil may leak from the state in which the supply pressure is not applied to the O-ring until the supply of compressed air is started and a sufficient sealing property is ensured. Further, since a very small amount of oil may leak even due to the sliding of the timer piston 80, oil may be introduced into the flow path communicating with the choke 9.
Therefore, as shown in
The choke 9 communicates with the timer piston housing 82F via the discharge flow path 90 and communicates with a flow path formed between the timer piston housing 82E and the timer piston shaft 86. The flow path formed between the timer piston housing 82E and the timer piston shaft 86 is shut off from the flow path formed between the timer piston housing 82D and the timer piston shaft 86 by the O-ring.
In this way, the flow path formed between the timer piston housing 82D and the timer piston shaft 86 and the atmosphere are communicated with each other by the foreign matter discharge flow path 93, so that it is possible to suppress oil or the like from entering the flow path formed between the timer piston housing 82E and the timer piston shaft 86. Therefore, oil is suppressed from entering the flow path communicating with the choke 9, and the accumulation of oil is suppressed, so that the performance of the choke 9 can be maintained and the influence on the time-out time can be suppressed.
Further, in the timer 8, the axial position of the needle 92 can be adjusted by using a screw so that the time until the time-out can be set to a predetermined reference time. In order to make it easier to adjust the needle 92 from the outside, the choke 9 is provided on an end cap 11a of the handle 11, and the needle 92 can be adjusted from the outside of the end cap 11a. The choke 9 can be mounted to the handle 11 after being assembled to the end cap 11a. Therefore, compared to the case where the choke 9 is assembled inside the handle 11, assembling work becomes easier, the choke 9 can be easily adjusted for each machine body so that the time until the time-out becomes the reference time, and it is possible to deal with individual differences in parts.
Therefore, the nailing machine 1A includes a throttling amount adjustment part 94 of the choke 9, a spring force adjustment part 95, and a volume adjustment part 96. The throttling amount adjustment part 94 makes it possible to adjust the throttling amount in two steps by adjusting the position of the needle 92 in a stepwise manner, in this example, in two steps by the displacement of a throttling amount adjustment lever 94b with a shaft 94a as a fulcrum.
The spring force adjustment part 95 makes it possible to adjust the spring force of the timer piston spring 81 that urges the timer piston 80 in a stepless manner with a screw or in a stepwise manner with a lever or the like. The volume adjustment part 96 makes it possible to adjust the volume of the discharge flow path 90 in a stepless manner with a screw or in a stepwise manner with a lever or the like.
In
In
In
In this way, a user can easily and reliably adjust the time until the time-out, so that it is possible to adjust whether to prioritize safely or operability according to the user's preference.
<Configuration Example of a Nailing Machine of a Second Embodiment>
<Operation Example of the Nailing Machine of the Second Embodiment>
Next, the operation of the nailing machine 1B of the second embodiment will be describe d with reference to each drawing.
In this way, as described above, the main valve 4 is urged by the main valve spring 41 and located in the top dead center position. Further, in the trigger valve 5, the pilot valve 50 is urged by the trigger valve stem spring 54 and held in the non-operating position. Furthermore, in the trigger valve 5, the trigger valve stem 52 is urged by the trigger valve stem spring 54 and held in the non-operating position. Further, in the trigger valve 5, the timer switch 56 is urged by the timer switch spring 59 and held in the non-operating position.
When the timer switch 56 of the trigger valve 5 is in the non-operating position, the main chamber 3 communicates with the second timer operating flow path 33b. Since a hose from an air compressor (not shown) is not connected to the chuck 30, the main chamber 3 is in a state of communicating with the atmosphere. In this way, in the timer 8, the preset piston 83 is urged by the preset piston spring 84 and held in the non-operating position. Further, in the timer 8, the timer piston 80 is urged by the timer piston spring 81 and held in the non-operating position. Furthermore, in the timer 8, the on-off valve part 87G is pushed by the timer piston shaft 86 of the timer piston 80 and is moved to an opening position of opening the flow path communicating the inflow flow path 35 and the operation regulating flow path 34 with each other.
In this way, the main valve 4 is held in the top dead center position. Further, in the trigger valve 5, the pilot valve 50 is held in the non-operating position. Furthermore, in the trigger valve 5, the trigger valve stem 52 is held in the non-operating position. Further, in the trigger valve 5, the timer switch 56 is held in the non-operating position in a state where the trigger 6 does not operate.
When the timer switch 56 of the trigger valve 5 is in the non-operating position, the main chamber 3 communicates with the second timer operating flow path 33b. When a hose from an air compressor (not shown) is connected to the chuck 30, the main chamber 3 has the supply pressure. In this way, in the timer 8, the preset piston 83 is pushed by the air pressure corresponding to the supply pressure and is moved to the timekeeping start position. Further, in the timer 8, the timer piston 80 is pushed by the preset piston 83 and is moved to the timekeeping start position. Furthermore, in the timer 8, the on-off valve part 87G is pushed by the preset piston 83 and is moved to a closing position of closing the flow path communicating the inflow flow path 35 and the operation regulating flow path 34 with each other. In this way, the supply pressure is not supplied to the operation regulating flow path 34.
When the timer switch 56 of the trigger valve 5 is in the operating position, the first timer operating flow path 33a and the second timer operating flow path 33b communicates with each other. The blowback chamber 31 communicates with the atmosphere. In this way, in the timer 8, the preset piston 83 is urged by the preset piston spring 84 and starts to advance from the timekeeping start position. Further, in the timer 8, the timer piston 80 is urged by the timer piston spring 81 and starts to advance from the timekeeping start position.
Even if the trigger 6 is operated, the contact lever 70 does not push the trigger valve stein 52 in a state where the butting portion 71 of the contact arm 7 is not butted against a member to be driven.
On the contrary, the timer piston front chamber 80c, which is formed by moving the timer piston 80 to the operating position, communicates with the atmosphere via the choke 9. In this way, the timer piston 80 advances with a delay with respect to the preset piston 83.
The timer piston 80 advances in a shorter time up to a predetermined position where the pressure in the timer piston front chamber 80c rises to a certain degree, as compared with the time from 0 seconds from the operation of the trigger to the end of timekeeping. Further, from the predetermined position where the pressure in the timer piston front chamber 80c rises to a certain degree to the non-operating position, the discharge amount of air throttled by the choke 9 becomes a load against the urging by the timer piston spring 81, and the timer piston 80 is moved at a lower speed with respect to the moving speed up to the predetermined position where the pressure in the timer piston front chamber 80c rises to a certain degree.
From 0 seconds from the operation of the trigger to the end of timekeeping, that is, during the period in which the timer piston 80 starts to advance from the timekeeping start position and is moved to the non-operating position, the pressing portion 72 of the contact arm 7 pushes the contact lever 70 when the contact arm 7 shown in
When the trigger 6 is moved to the operated position, the acting portion 70a of the contact lever 70 pushes the trigger valve stem 52. In the trigger valve 5, the flow path communicating the trigger valve lower chamber 55 with the main chamber 3 is closed and the flow path communicating the trigger valve lower chamber 55 with the operation regulating flow path 34 is opened when the trigger valve stem 52 is moved upward by a predetermined amount.
Further, while the timer piston 80 is moved from the timekeeping start position to the non-operating position, the flow path formed between the timer piston housing 82A and the timer piston shaft 86 and the flow path formed between the preset piston housing 85 and the preset piston shaft 83a communicate with each other.
In this way, the trigger valve lower chamber 55 communicates with the atmosphere and compressed air is discharged therefrom, so that the air pressure in the trigger valve lower chamber 55 decreases. Therefore, the pilot valve 50 is moved downward, and the first air flow path 32 is opened.
When the first air flow path 32 is opened, the main valve lower chamber 42 is shut off from the main chamber 3 and communicates with the atmosphere. Then, compressed air is discharged from the main valve lower chamber 42, and the air pressure in the main valve lower chamber 42 decreases, in this way, the main valve 4 is moved downward, and the top opening portion 44 is opened. Therefore, the compressed air in the main chamber 3 is supplied to the striking cylinder 2.
In this way, the striking cylinder 2 is operated by the compressed air, the striking piston 21 is moved in the direction of striking out a nail (not shown), and the striking driver 20 performs a striking operation. Further, a part of the compressed air in the striking cylinder 2 is supplied from the inflow/discharge port 31a, to the blowback chamber 31.
After the striking operation, compressed air is supplied from the blowback chamber 31 to the striking cylinder 2, the striking piston 21 is moved in the direction of returning the striking driver 20, and the striking piston 21 returns to the top dead center position. When the striking piston 21 returns to the top dead center position, the blowback chamber 31 is in a state of communicating with the atmosphere.
In this way, in the timer 8 after being reset, the preset piston 83 is urged by the preset piston spring 84 and starts to advance from the timekeeping start position. Further, in the timer 8, the timer piston 80 is urged by the timer piston spring 81 and starts to advance from the timekeeping start position. Therefore, the timekeeping is initiated,
In the timer 8, the on-off valve part 87G is pushed by the timer piston shaft 86 of the timer piston 80 and is moved to the opening position of opening the flow path communicating the inflow flow path 35 and the operation regulating flow path 34 with each other when the timer piston 80 is moved to the non-operating position. In this way, compressed air is supplied from the main chamber 3 to the operation regulating flow path 34.
When the trigger 6 is moved to the operated position; the acting portion 70a of the contact lever 70 pushes the trigger valve stem 52. In the trigger valve 5, the trigger valve lower chamber 55 communicates with the operation regulating flow path 34 when the trigger valve stem 52 is moved upward by a predetermined amount. When the on-off valve part 87G is moved to the opening position, compressed air is supplied from the main chamber 3 to the operation regulating flow path 34. In this way, the trigger valve lower chamber 55 has a supply pressure by compressed air supplied from the main chamber 3 via the operation regulating flow path 34.
Therefore, the pilot valve 50 is held in the upper position due to the relationship between the balance of the air pressure of compressed air and the force of the trigger valve stem spring 54. In this way, the first air flow path 32 is not opened, the main valve 4 is held at the top dead center position, and the striking cylinder 2 does not operate.
<Configuration Example and Operation Example of a Nailing Machine of Another Embodiment>
The first and second embodiments adopt the structure using the meter-out control in which the moving speed of the timer piston is controlled by adjusting the outflow of air compressed by the timer piston pushed by the urging member such as the spring. On the contrary, instead of the throttle disposed on the outflow side of the timer piston cylinder, the throttle may be disposed on the inflow side, and a meter-in control may be adopted in which the moving speed of the piston is controlled by adjusting the amount of air flowing into the cylinder by the piston moved by the urging force of the spring.
The choke 9C includes an inflow/outflow flow path 90C1 communicating with the main chamber 3, the filter 91 provided in the inflow/outflow flow path 90C1, the needle 92 for throttling the inflow/outflow flow path 90C1, and an inflow/outflow flow path 90C2 communicating with the timer piston cylinder 80d. The choke 9C is attached to the handle 11 via a Y-ring 97a having a Y-shaped cross section. The Y-ring 97a is an example of a check valve, and opens and closes a flow path 97b formed on the outer periphery of the choke 9C according to the direction in which air flows.
The Y-ring 97a is deformed in the direction in which the flow path 97b on the outer periphery of the choke 9C is opened by the pressure of air flowing from the timer piston cylinder 80d into the main chamber 3, and the flow path 97b is opened. Further, the Y-ring 97a is deformed in the direction in which the flow path 97b is closed by the pressure of air flowing from the main chamber 3 to the timer piston 80d, and the flow path 97b is closed.
Further, the nailing machine 1C includes a discharge flow path 93C that communicates the atmosphere with the timer piston front chamber 80c formed by moving the timer piston 80 to the timekeeping start position. The discharge flow path 93C communicates with the timer piston cylinder 80d via a flow path or the like formed between the timer piston housing 82D and the timer piston housing 82E, but a throttle such as the choke 9 is provided therein.
In the nailing machine 1C, similarly to the nailing machine 1A of the first embodiment, the timer piston shaft 86 constituting the on-off valve part 87 is formed such that the diameter of the shaft portion 86b on the side opposite to the timer piston 80 is larger than the diameter of the shaft portion 86a on the side of the timer piston 80 with the flow path forming recess 87b interposed therebetween. In the timer piston shaft 86, the pressure receiving surface 87H that receives the force of the compressed air supplied from the main chamber 3 is formed by the diameter difference of the timer piston shaft 86, which is the difference between the diameter of the shaft portion 86a and the diameter of the shaft portion 86b, and the supply pressure is applied to the timer piston shaft 86 constituting the on-off valve part 87.
Other configurations are the same as those of the nailing machine 1A of the first embodiment.
Hereinafter, the operation of the nailing machine 1C of another embodiment will be described with reference to each drawing. In a state where a hose from an air compressor (not shown) is not connected and compressed air is not supplied, as shown in
In the nailing machine 1C, when a hose from an air compressor (not shown) is connected and compressed air is supplied into the main chamber 3, as shown in
In the timer 8C, as the timer piston 80 moves to the timekeeping start position, the pressure in the timer piston rear chamber 80e increases with the decrease in the volume of a timer piston rear chamber 80e. When the pressure in the timer piston rear chamber 80e increases and the pressure of air flowing from the timer piston cylinder 80d into the main chamber 3 is applied to the Y-ring 97a, the Y-ring 97a is deformed in the direction in which the flow path 97b on the outer periphery of the choke 9C is opened, and the flow path 97b is opened. In this way, air is introduced from the timer piston rear chamber 80e into the main chamber 3 without passing through the choke 9C, and the timer piston 80 is moved to the timekeeping start position.
As shown in
When the preset piston 83 is moved to the non-operating position, the force for pressing the timer piston 80 to the timekeeping start position is released. When the supply pressure in the main chamber 3 is applied to the Y-ring 97a, the Y-ring 97a is deformed in the direction in which the flow path 97b on the outer periphery of the choke 9C is closed, and the flow path 97b is closed. In this way, air is introduced from the main chamber 3 to the timer piston rear chamber 80e via the choke 9C, and as shown in
In the timer 8C, the air in the main chamber 3 is supplied to the timer piston rear chamber 80e via the choke 9C, and the timer piston 80 moved to the timekeeping start position is pressed by the air whose flow rate is throttled by the choke 9C. Further, in the timer 8C, the air in the timer piston front chamber 80c is discharged from the discharge flow path 93C into the atmosphere. In this way, the timer piston 80 is pressed by the air whose flow rate is throttled by the choke 9C, and the moving speed of the timer piston 80 is controlled.
When the contact arm 7 shown in
Further, during the striking operation, the preset piston 83 of the timer 8C is pushed by air pressure corresponding to the supply pressure of compressed air and is moved to the timekeeping start position. Further, the timer piston 80 is pushed by the preset piston 83 and is moved to the timekeeping start position, and the timer 8C is reset.
In the timer 8C after being reset by the striking operation, the preset piston 83 advances from the timekeeping start position and moves to the non-operating position by being urged by the preset piston spring 84. Further, in the timer 8C, as described above, the air in the main chamber 3 is supplied to the timer piston rear chamber 80e via the choke 9C, and the timer piston 80 moved to the timekeeping start position advances by being pressed by the air whose flow rate is throttled by the choke 9C, and the timekeeping is initiated.
When the contact arm 7 shown in
In the timer 8C, the on-off valve part 87 is opened when the timer piston 80 is moved to the non-operating position. When the on-off valve part 87 is opened, as described above, the trigger 6 is in a state of being moved to the operated position, and the striking cylinder 2 does not operate even when the contact arm 7 shown in
In the operation of the timer piston 80 moving from the timekeeping start position to the non-operating position, as described above, the sliding resistance of the on-off valve part 87 and the like using the O-ring as the sealing member becomes large due to the influence of the supply pressure, which affects the time until the time-out. Therefore, the pressure receiving surface 87H that receives the force of compressed air supplied from the main chamber 3 is formed on the timer piston shaft 86 constituting the on-off valve part 87, and a force that cancels the sliding resistance by using the supply pressure is applied to the timer piston 80.
In the configuration in which the pressure receiving surface 87H using the diameter difference of the timer piston shaft 86 generates a force that pushes the timer piston shaft 86 in the axial direction by the supply pressure, similarly to the sliding resistance, the force that pushes the timer piston shaft 86 also increases as the supply pressure increases.
Therefore, the force that pushes the timer piston shaft 86 in the axial direction by the supply pressure is generated in the direction of cancelling the sliding resistance. In this way, even when the sliding resistance between the timer piston shaft 86 and the O-ring 87a increases in proportion to the supply pressure, the force that pushes the timer piston shaft 86 in the axial direction also increases by the pressure receiving surface 87H, so that the change in sliding resistance can be cancelled.
Further, the timer piston housings 82A to 82F have the same configuration as those in the nailing machine 1A of the first embodiment and can obtain the same effect as that of the nailing machine 1A of the first embodiment by having a configuration for improving accuracy and a configuration for securing a flow path, and the like.
Although, in each of the above-described embodiments, the timer piston is pushed by an urging member such as a spring, the timer piston may be pushed by air pressure. In the following example, a meter-out control in which the throttle is arranged on the outflow side of the timer piston cylinder will be described as an example, but a meter-in control in which the throttle is arranged on the inflow side of the timer piston cylinder may be adopted.
As shown in
The Y-ring 97a is deformed in the direction in which the flow path 97b on the outer periphery of the choke 9D is opened by the pressure of air flowing from the inflow/outflow flow path 90D1 to the timer piston cylinder 80d, and the flow path 97b is opened. Further, the Y-ring 97a is deformed in the direction in which the flow path 97b is closed by the pressure of air flowing from the timer piston cylinder 80d to the inflow/outflow flow path 90D1, and the flow path 97b is closed.
Further, the timer 8D includes a discharge flow path 88D communicating the timer piston housing 82A with the atmosphere. In the timer 8D, the air in the timer piston housing 82A is discharged from the discharge flow path 88D to the outside by the operation of moving the timer piston.
In the nailing machine 1D, similarly to the nailing machine 1A of the first embodiment, the pressure receiving surface 87H that receives the force of compressed air supplied from the main chamber 3 is formed on the timer piston shaft 86 constituting the on-off valve part 87 by the difference between the diameter of the shaft portion 86a and the diameter of the shaft portion 86b, and the supply pressure is applied to the timer piston shaft 86 constituting the on-off valve part 87.
Other configurations are the same as those of the nailing machine 1A of the first embodiment.
Hereinafter, the operation of the nailing machine 1D of another embodiment will be described with reference to each drawing. In a state where a hose from an air compressor (not shown) is not connected and compressed air is not supplied, as shown in
In the nailing machine 1D, when a hose from an air compressor (not shown) is connected and compressed air is supplied into the main chamber 3, the compressed air in the main chamber 3 is supplied to the timer piston housing 82H and the pressure in the timer piston housing 82H increases. When the pressure in the timer piston housing 82H increases and the supply pressure is applied to the Y-ring 97a via the inflow/outflow flow path 90D1, the V-ring 97a is deformed in the direction in which the flow path 97b on the outer periphery of the choke 9D is opened, and the flow path 97b is opened. In this way, air is introduced from the timer piston housing 82E to the timer piston cylinder 80d without passing through the choke 9D, and as shown in
As shown in
In the timer 8D, as shown in
When the throttle of the choke 9D is narrowed to the point where only a very small amount of air flows, the timer piston front chamber 80c can be regarded as being substantially sealed at the moment when the timer piston 80 is moved. Thus, the volume of the timer piston front chamber 80c is reduced by the amount of movement of the timer piston 80, and the pressure is increased by that amount. When the spring force of the timer piston spring 81 and the surface pressure of the air pressure due to internal compression are balanced, the timer piston 80 can advance by the amount of air released via the choke 9D from that time. In this way, the moving speed of the timer piston 80 is controlled.
When the contact arm 7 shown in
Further, during the striking operation, in the timer 8D, compressed air is supplied to the timer piston housing 82H and the pressure in the timer piston housing 82H increases. When the pressure in the timer piston housing 82H increases, as shown in
In the timer 8D after being reset by the striking operation, the timer piston 80 advances by being urged by the timer piston spring 81, and the timekeeping is initiated.
When the contact arm 7 shown in
In the timer 8D, the on-off valve part 87 is opened when the timer piston 80 is moved to the non-operating position. When the on-off valve part 87 is opened, as described above, the trigger 6 is in a state of being moved to the operated position, and the striking cylinder 2 does not operate even when the contact arm 7 shown in
In the operation of the timer piston 80 moving from the timekeeping start position to the non-operating position, as described above, the sliding resistance of the on-off valve part 87 and the like using the O-ring as the sealing member becomes large due to the influence of the supply pressure, which affects the time until the time-out. Therefore, the pressure receiving surface 87H that receives the force of compressed air supplied from the main chamber 3 is formed on the timer piston shaft 86 constituting the on-off valve part 87, and a force that cancels the sliding resistance by using the supply pressure is applied to the timer piston 80.
In the configuration in which the pressure receiving surface 87H using the diameter difference of the timer piston shaft 86 generates a force that pushes the timer piston shaft 86 in the axial direction by the supply pressure, similarly to the sliding resistance, the force that pushes the timer piston shaft 86 also increases as the supply pressure increases.
Therefore, the force that pushes the timer piston shaft 86 in the axial direction by the supply pressure is generated in the direction of cancelling the sliding resistance. In this way, even when the sliding resistance between the timer piston shaft 86 and the O-ring 87a increases in proportion to the supply pressure, the force that pushes the timer piston shaft 86 in the axial direction also increases by the pressure receiving surface 87H, so that the change in sliding resistance can be cancelled.
Further, the timer piston housings 82A to 82F have the same configuration as those in the nailing machine 1A of the first embodiment and can obtain the same effect as that of the nailing machine 1A of the first embodiment by having a configuration for improving accuracy and a configuration for securing a flow path, and the like.
Therefore, as shown in
The volume adjustment part 95C makes it possible to adjust the volume of the timer piston cylinder 80d in a stepless manner with a screw or in a stepwise manner with a lever or the like.
In
As shown in
The spring force adjustment part 95D makes it possible to adjust the spring force of the timer piston spring 81 that urges the timer piston 80 in a stepless manner with a screw or in a stepwise manner with a lever or the like. The volume adjustment part 96D makes it possible to adjust the volume of the inflow/outflow flow path 90D2 in a stepless manner with a screw or in a stepwise manner with a lever or the like.
In
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| 2020-113614 | Jun 2020 | JP | national |
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