Patent Application
20060000863
1. Field of the Invention
This application relates to fastener driving devices and more particularly to power operated fastener driving devices having a system for avoiding the problems associated with dry firing.
2. Description of Related Art
Fastener driving devices of the power operated variety can be either pneumatically operated, electrically operated or internal combustion operated. Such devices involve the expenditure of energy at a level which makes it important that each operation constitutes a desired operation for driving a fastener into a workpiece. Much of the available energy is used up in the driving action itself. Consequently, when the device is operated without a fastener in the drive track to be driven, all of the energy normally provided to effect the driving action must be absorbed by the piston hitting the rubber bumper at the end of the drive stroke of the fastener driver. Where a dry firing of this type takes place after each fastener supply provided by the magazine assembly is exhausted, considerable damage and wear to the bumper and intimately related components, as well as damage to the workpiece, can occur. In recognition of this damage possibility, many power operated fastener driving devices have been equipped with some sort of dry firing prevention mechanism.
One example of a dry firing prevention mechanism is disclosed in U.S. Pat. No. 6,012,622. Essentially, dry firing is prevented by sensing fastener depletion and locking out the contact trip assembly in its extended position in response to a depletion signal or movement by the sensor. While arrangements of this type effectively reduce dry fire related component damage, experience has shown that other areas of possible damage are brought into being. The contact trip element when in its extended position is intentionally located so that it is the first structure to be engaged with another structure by the user in normal operation. This location makes it susceptible to being either deliberately or accidentally engaged when the depletion system has locked the contact trip element in its extended position The result is that with lockout depletion sensing systems of the prior art, damage to the contact trip assembly sometimes takes place which would not otherwise take place in the absence of the lockout depletion sensing system. There is still a need for a depletion sensing system which can effectively protect not only components susceptible to dry fire damage, but the contact trip assembly as well.
An aspect of the present invention is to fulfill the need expressed above. The underlying concept of the invention is to fundamentally change the device from one in which dry firing is prevented by locking the contact trip assembly in its extended position to one which enables the contact trip assembly to be moved from its extended position into its actuated position under extreme situations where damage is likely, as for example, when the tool is dropped and lands on the extended contact trip element in such a way as to bend or otherwise damage it.
It is another aspect of the present invention to provide the user with a fastener depletion signal or indication which occurs and can be tactilely sensed during actuation and which enables the user either to cease further operation or complete the operation following the indication depending upon the specific depletion indication by the particular device. That is, if the indication is predetermined to be one indicating when the fasteners have been depleted to zero, the user will want to cease further operation. On the other hand, if the indication is predetermined to be one indicating when the fasteners have been depleted to one or more than one, the user will want to complete the operation following the indication until all of the fasteners have been depleted.
In an embodiment described below, the fastener depletion signal utilized is predetermined to be one indicating zero fasteners are present, thus indicating to the user to cease further operation. Preferably, the preferred zero depletion signal is a yieldable resistance to actuation which is sufficiently great to enable the user to cease further normal actuating movement. However, the resistance will yield and permit actuation of the contact trip assembly under extreme unwanted accidental actuation situations that are beyond normal, such as the dropping of the tool.
In an embodiment, an actuating mechanism which is operable only by first moving the contact trip assembly against the workpiece into its actuating or operative position and thereafter manually moving the trigger into its actuating position. With this sequential only arrangement, when the user feels the zero depletion signal, the user simply does not move the trigger from its inoperative position, but instead takes action to reload the magazine assembly with a new supply of fasteners.
Aspects of the present invention are not limited to sequential only operation but are also applicable to concomitant type actuation as well. In this actuation arrangement, the user must cease further actuating movement of the contact trip assembly in engagement with the workpiece. Here again, the user action called for is a replenishing of the supply of fasteners in the magazine assembly, after either removing the tool from the workpiece and/or removing the finger from the trigger. The user readily understands that sensing the resistance of the fastener depletion signal does not mean to push harder on the tool against the workpiece with the trigger squeezed, indeed, just the opposite as aforesaid. Thus, in the normal operation of the present invention, dry firing will not take place, thereby protecting components susceptible to dry firing damage, while at the same time protecting the contact trip assembly from damage of the type experienced with tools having the prior art lockout arrangements.
In accordance with aspects of the present invention, the fulfillment of the expressed need is achieved by providing a fastener driving device. The device includes a portable housing assembly that defines a fastener drive track, a fastener driver that is movably mounted in the drive track, a magazine assembly that is constructed and arranged to feed successive leading fasteners from a supply of fasteners contained therein along a feed track and into the drive track, and a power operated system that is constructed and arranged to be actuated so as to move the fastener driver through successive operative cycles. Each cycle includes a drive stroke in which a fastener in the drive track is driven into a workpiece, and a return stroke. The device also includes an actuating mechanism that includes a contact trip assembly and a trigger assembly that is constructed and arranged to actuate the power operated system in response to a predetermined cooperative movement between the contact trip assembly and the trigger assembly, and a fastener depletion sensing system that is constructed and arranged to allow normal operation of the power system so long as the supply of fasteners provided by the magazine assembly is such that more than a predetermined number of fasteners are in the feed track and/or the drive track. The fastener depletion sensing system is operable, when the predetermined number of fasteners in the feed track and/or the drive track is reached, to provide a tactile indication to the user that the predetermined number of fasteners has been reached, and permitting the user to either cease further operation following the indication or complete the operation following the indication.
According to an aspect, a fastener driving device is provided. The fastener driving device includes a portable housing assembly that defines a fastener drive track, a fastener driver that is movably mounted in the drive track, a magazine assembly that is constructed and arranged to feed successive leading fasteners from a supply of fasteners contained therein along a feed track and into the drive track, and a power operated system that is constructed and arranged to be actuated so as to move the fastener driver through successive operative cycles. Each cycle includes a drive stroke wherein a fastener in the drive track is driven into a workpiece and a return stroke. The device also includes an actuating mechanism that includes a contact trip assembly and a trigger assembly constructed and arranged to actuate the power operated system in response to a predetermined cooperative movement between the contact trip assembly and the trigger assembly. The contact trip assembly is constructed and arranged to be moveable between an inoperative position and an operative position with an application of a force thereon. The device further includes a fastener depletion sensing system that includes at least two surfaces that engage one another to prevent actuation of the power operated system upon a predetermined amount of fasteners in the feed track and/or the drive track being reached. A further application of force to the contact trip assembly after the indication allows the surfaces to slide past one another so that the contact trip assembly is able to move to the operative position, thereby protecting the contact trip assembly upon the further application of force.
It is another aspect to provide a method for driving a fastener with a fastener driving device. The method includes actuating a power operated system that moves a fastener driver through successive operative cycles. Each cycle includes a drive stroke that drives one of a supply of fasteners and a return stroke. The actuating includes pressing a contact trip assembly to a workpiece so as to move the contact trip assembly from an inoperative position to an operative position, and moving a trigger assembly from an inoperative position to an operative position. The method also includes sensing that the supply of fasteners is at or below a predetermined number of fasteners, and determining whether to continue actuating the power operated system by applying an additional force to the contact trip assembly or to reload the supply of fasteners prior to continuing actuating the power operated system.
These and other aspects of the invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are part of this disclosure and which illustrate, by way of example, the principles of this invention.
Features of the invention are shown in the drawings, in which like reference numerals designate like elements. The drawings form part of this original disclosure, in which:
Referring now more particularly to the drawings, there is shown in
Specifically, the pneumatically powered fastener driving device 10 shown in
The reservoir 18 communicates with a manually operable trigger valve assembly 22, which controls the communication of the reservoir to a pilot pressure chamber 24 of a main valve assembly 26. The main valve assembly 26 is housed within a cap assembly 28, fixed to the top of a main housing section 30, that is integral with and extending generally perpendicular to the handle section 16, both of which form parts of the portable housing assembly 14.
Mounted within the main housing section 30 is a cylinder 32, an upper end of which cooperates with the main valve assembly 26 to enable the main valve assembly 26 to function in the usual fashion when in an inoperative position, wherein the pilot pressure chamber 24, under the control of trigger valve assembly 22 in its inoperative position, is communicated with the reservoir 18. When in its inoperative position, the main valve assembly 26 also functions to communicate the open upper end of the cylinder 32 with atmosphere through the cap assembly 28.
When the trigger valve assembly 22 is manually moved from its inoperative position into an operative position, the pilot pressure chamber 24 is shut off from communication with the reservoir 18 and communicated with atmosphere. The pressure from the reservoir 18 then acts upon the main valve assembly 26 to move it from its inoperative position into an operative position. In its operative position, the main valve assembly 26 functions to shut off the communication of the open upper end of the cylinder 32 with the atmosphere and to allow full peripheral communication thereof with the reservoir 18.
Communication of the reservoir 18 with the open upper end of the cylinder 32 serves to drive a piston 34 slidably mounted within the cylinder 32 through a fastener drive stroke which is completed when the piston 34 engages a shock absorbing bumper 36 mounted in the main housing section 30 below the lower end of the cylinder 32 which is fixed therein.
The drive stroke of the piston 34 constitutes one stroke of a two stroke cycle of movement that the piston 34 undergoes on a successive basis in accordance with the manual actuating movement of the trigger valve assembly 22. The other stroke of the piston 34, which constitutes a return stroke, is accomplished by a suitable return system 38. The return system can be of any known type. As shown, the return system 38 is of the air plenum chamber type.
The drive stroke of the piston 34 serves to move a fastener driver 40 connected therewith through a drive stroke within a drive track 42 formed within a nose piece assembly 44 fixed below the lower end of the main housing section 30 and forming a part of the portable housing assembly 14. The drive stroke of the fastener driver 40 serves to drive a leading fastener from a supply of fasteners contained within a fastener magazine assembly 46 which has been laterally moved into the drive track 42 along a feed track 48 defined by the magazine assembly 46.
The magazine assembly 46, which is fixed to the nose piece assembly 44 and extends below and is fixed to the handle section 16, can be of any known type. The magazine assembly 46, as shown, is a conventional side loader capable of handling fasteners in a stick formation supply, as shown, or a coil formation supply of any well known configuration.
The trigger valve assembly 22 is manually actuated by an actuating mechanism which includes a trigger assembly 50 and a contact trip assembly 52. A complete actuation movement serves to move the trigger valve assembly 22 from its inoperative position into its operative position by the coordinated movement of the trigger assembly 50 and contact trip assembly 52, both of which may be of any conventional construction so as to require any known coordination to effect operation. In the illustrated embodiment, actuation requires a specific sequential movement. That is, the cooperation between the trigger assembly 50 and the contact trip assembly 52 is such that the trigger valve assembly 22 will be moved from its inoperative position into its operative position only when the contact trip assembly 52 is first moved against the workpiece and into its operative position and thereafter the trigger assembly 50 is manually moved into its operative position.
In the broadest aspects of the present invention, the device 10 can be adapted to handle any fastener configuration. However, in the embodiment shown, the feed track 48 is configured to receive therein a supply of finishing nail fasteners in stick formation. The magazine assembly 46 includes a pusher 54, the illustrated embodiment of which is shown as a sheet metal structure having a width slightly greater than the diameter of the finishing nails. The pusher 54 is slidably mounted in the feed track 48 and is spring-biased to move in a direction toward the drive track 42. As best shown in
In accordance with an embodiment of the present invention, the fastener depletion sensing system 12 includes a fastener depletion sensor 62 constructed and arranged to provide a fastener depletion signal in response to the depletion of fasteners in the fastener supply provided by the magazine assembly 46 such that only a predetermined number of fasteners remain in the feed track 48 and/or the drive track 42. Preferably, the predetermined number is be based on the combined number of fasteners that remain in the feed track 48 and the drive track 42. It is understood that the predetermined number may be any number of fasteners. Preferably, the predetermined number is within the range of zero to three inclusive. In the illustrated embodiment, the predetermined number is zero. Preferably, the sensor 62 is a movable signaling member constructed and arranged to provide a fastener depletion signal in the form of a sensing movement thereof in response to the number of fasteners in the feed track 48 reaching zero. In the embodiment shown, the sensor 62 is in the form of a laterally extending flange-like element formed integrally as part of the sheet metal structure of the pusher 54.
The fastener depleting sensing system 12 also includes a yieldable assembly, generally indicated at 64, operatively associated with the contact trip assembly 52 of the actuating mechanism and the fastener depletion sensor 62. The yieldable assembly 64 is constructed and arranged to allow normal operation of the contact trip assembly 52 so long as the supply of fasteners contained in the feed track 48 is greater than zero and to provide a signal in the form of a predetermined yielding resistance to the actuation of the contact trip assembly 52 when a fastener depletion signal has been provided by the fastener depletion sensor 62.
The contact trip assembly 52, in addition to its biasing spring, which is shown at 65 in
The operation of the adjustable connection is entirely conventional, it being noted, however, that it is greatly preferred to have the yieldable assembly 64 cooperate with the trigger assembly engaging contact trip member 68 since its position remains the same after adjustment, whereas the workpiece engaging contact trip member 66 assumes a different position after adjustment requiring accommodation.
The preferred configuration of the yieldable assembly 64 is best shown in
As best shown in
The position of the parts in
It will be noted that during the return stroke of the fastener driver 40, as the lower end portion moves upwardly out of the drive track 42, the pusher 54 is operable under the actuation of springs 60 to move all of the remaining fasteners in the feed track 48 forwardly so that the leading fastener moves into the drive track 42. The device is then ready for another cycle of operation. When the last fastener has been moved from the feed track 48 into the drive track 42 during a preceding operative cycle, the sensor 62 moves forward into engagement with the surface 76 of the yieldable blocking member 72. Now, when the last nail in the drive track 42 is driven in the next cycle and the fastener driver 40 is withdrawn during the return stroke, the pusher 54 is biased by springs 60 to enter the drive track 42 carrying with it the sensor 62 in engagement with the surface 76 of the yieldable blocking member 72.
The pusher springs 60 and the yieldable blocking member spring 74 form a counterbalanced spring system enabling the springs 60 to overcome the bias of the spring 74 so that as the pusher 54 is moved into the drive track 42, the sensor 62 will move the yieldable blocking member 72 about its pivotal axis against the bias of spring 74, in a clockwise direction as viewed in
Since the preferred actuation arrangement involves an actuating mechanism which is operable only be first moving the contact trip assembly 52 against the workpiece into its actuating or operative position and thereafter manually moving the trigger assembly 50 into its actuating position, when the user feels the zero depletion signal, the user simply does not move the trigger assembly 50 from its inoperative position. Instead, the user takes action to reload the magazine assembly 46 with a new supply of fasteners. The principles of the present invention are not limited to sequential only operation, but are also applicable to concomitant type actuation as well. In this type of actuation, the user must cease further actuation movement of the contact trip assembly 50 in engagement with the workpiece. Here again, the user action called for is a replenishing of the supply of fasteners in the magazine assembly 46 after either removing the tool 10 from the workpiece and/or removing the finger from the trigger assembly 50. The user readily understands that sensing the resistance of the fastener depletion signal does not mean to push harder on the tool 10 against the workpiece with the trigger assembly 50 squeezed. Indeed, just the opposite action is called for as aforesaid.
If for any reason the user puts the device 10 down in the condition shown in
The movement of the contact trip element 68 beyond the yieldable blocking member 72 is shown in
The descriptions above are intended to be illustrative, not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.
