Patent Application
20180326527
The present disclosure relates generally to welding equipment, including welders and welding guns. Specifically, the present disclosure relates to a 12 volt spool gun.
Many small wire welders that are available are equipped with a welding gun for the purpose of delivering welding wire to a welding arc to be consumed as a filler metal in a weldment. Typically, the welding wire is pushed through a gun cable by a welding wire drive mechanism located in the welder. However, when welding with a soft filler metal, such as aluminum, the feeding of the welding wire through the welding gun may be problematic as soft welding wire is prone to binding in some welding guns. The welding wire feeding issues encountered may cause temporary or total arc outages. In the worst case, the wire may feed back into the welder, causing a “bird's nest” of welding wire in the welding wire drive mechanism.
One method for resolving this issue is to employ a welding gun with a shorter welding wire travel path to minimize the welding wire restrictions. Such a welding gun is known as a “spool gun” because the welding wire spool and welding wire drive mechanism are located in a handle end of the spool gun closest to the welding arc. This configuration allows softer filler metal welding wire to be delivered to the welding arc in a straight, short (e.g., approximately 10″) path. Since the welding wire spool and welding wire drive mechanism are located in the spool gun rather than the welder, power must be provided to the spool gun to drive a motor within the spool gun.
Unfortunately, many existing welders are not readily adaptable to be used with a spool gun. Adapting a spool gun to a welder that is not “spool gun ready” may be an expensive and complicated exercise. This problem is exacerbated when the welder is a relatively low-cost welder.
Existing spool gun designs include a 24V motor. As such, it is relatively difficult and expensive to add circuitry to drive the motor in the spool gun since most of the small, low-cost wire drive welders utilize a lower voltage integrated wire drive motor and do not generally have the capability of delivering the proper motor voltage to the 24V spool gun. Most of these low cost wire welders derive power for their integrated wire drive motor from the welding arc. However, the arc voltage under load is typically too low to fully drive the spool gun motor to the desired speeds.
In an exemplary embodiment, a welding system includes a welding spool gun. The welding spool gun further includes a spindle configured to receive a welding wire spool, and a motor configured to drive rotation of a feed roll which draws welding filler metal wire from the welding wire spool. The motor is powered by a derived voltage derived from a welding arc voltage.
In another embodiment, a method includes deriving a derived voltage from a welding arc voltage and providing the derived voltage to a motor disposed in a welding spool gun.
In another embodiment, a welding system includes a welding power supply unit, and a welding spool gun coupled to welding power supply unit. The welding spool gun includes a spindle configured to receive a welding wire spool, and a motor configured to drive rotation of a feed roll which draws welding filler metal wire from the welding wire spool, in which the motor is powered by a derived voltage derived from a welding arc voltage.
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
The present disclosure provides a welding system wherein weld output power from a welder may be used to provide control power and 12 volt motor power to a spool gun directly or via a spool gun adapter. As such, the 12V spool gun presented herein provides a relatively inexpensive method of operating a spool gun with welders that may not otherwise be “spool gun ready.”
In some embodiments, the welder 12 may output a welding arc voltage, and the 12V spool gun 14 may include a motor rated at 12V, which is configured to accept as input a derived voltage that is derived from the welding arc voltage. For example, in certain embodiments, the 12V spool gun 14 may be powered by a maximum of approximately 17.6V DC input voltage.
As described in greater detail below, welding power from the welder 12 is delivered to the 12V spool gun 14 such that the 12V spool gun 14 may produce a welding arc on a workpiece 32. The 12V spool gun 14 will typically include a welding wire spool 18 of welding wire. The welding wire is advanced through the 12V spool gun 14 by a welding wire drive assembly, typically through the use of an electric motor under the control of control circuitry within either the 12V spool gun 14 or the welder 12. The workpiece 32 is coupled to the negative terminal of the welder output 24 via the work cable 34. The work cable 34, being coupled to the negative terminal of the welder output 24 on one end, may be coupled to the workpiece 32 on the opposing end via the work clamp 21, such that the workpiece 32 is electrically coupled to the negative terminal of the welder output 24, effectively “grounding” the workpiece 32 and completing a circuit from the welder 12 to the 12V spool gun 14 to the workpiece 32 (via a welding arc) and back to the welder 12.
Additionally, as illustrated, in certain embodiments, the welder 12 may be coupled to the welding gun adapter 20 via both the positive and negative terminals of the welder output 24, and supplies welding arc voltage to the welding gun adapter 20. The welding gun adapter 20 may filter the welding arc voltage received from the welder 12 into the derived voltage to be used for adapter circuit control and motor power for the connected 12V spool gun 14. However, in other embodiments, the welder 12 may be directly coupled to the 12V spool gun, in which the 12V spool gun may receive a derived voltage that is derived from the welding arc voltage of the welder 12. The derived voltage is generally a regulated voltage that is lower than the welding arc voltage from the welder 12. Generally, the derived voltage provided to the 12V spool gun 14 may be within a range of approximately 15V-30V. For example, the derived voltage may be 17.6V DC. In general, the derived voltage may be regulated such that it provides adequate operating power to a motor of the 12V spool gun 14, which is rated at 12V.
The 12V spool gun 14 also includes a trigger 33, which when activated, relays a trigger signal to a trigger circuit of the welder 12 via the welding gun adapter 20. When the trigger 33 of the 12V spool gun 14 is triggered, the welder 12 supplies weld power to the 12V spool gun 14 for establishing an arc, and to the welding gun adapter 20 for control power and power to drive the motor of the 12V spool gun 14. Thus, when the trigger 33 of the 12V spool gun 14 is activated, the welding wire spool 18 feeds welding wire through the 12V spool gun 14 to the welding arc created by welding power from the welder 12. As a result, the weld wire is molten, and a weld is made on the workpiece 32. In addition, in certain embodiments, the welding gun adapter 20 includes control circuitry, which regulates the feeding of welding wire from the welding wire spool 18 of the 12V spool gun 14.
In certain embodiments, the welder 12 is also coupled to a shielding gas source 35 via a gas hose 36. To shield the weld area from being oxidized or contaminated during welding, to enhance arc performance, and to improve the resulting weld, the welder 12 feeds the shielding gas to the 12V spool gun 14 via the welding gun cable 16, as previously mentioned. A variety of shielding materials for protecting the weld location may be employed, including inert shielding gas, including active gases, and particulate solids.
Additionally, in certain embodiments, the welding gun adapter 20 includes a knob 48 disposed on a surface of the welding gun adaptor 20. The knob 48 provides a user interfacing mechanism that may be used to control the motor speed of the motor of the 12V spool gun 14, how fast welding wire is delivered from the welding wire spool 18, and so forth. In certain embodiments, the knob 48 may be replaced with other user interfacing mechanisms for controlling motor speed, such as switches, buttons, sliders, and so forth. The welding gun adapter 20 may also include a physical attachment mechanism for securing the welding gun adapter 20 to the welder 12 as configured in
The circuit board 50 also includes a potentiometer 56 coupled to the adapter circuit. The potentiometer 56 is physically coupled to the knob 48 disposed on the surface of the welding gun adapter 20 such that the potentiometer 56 turns in a proportional manner when the knob 48 is turned. This allows a user to control the potentiometer 56, and hence the motor voltage and motor speed using the welding gun adapter 20. As illustrated, the circuit board 50 is disposed inside the adapter housing 38 such that the top cover 40 and the bottom cover 42 fully enclose the circuit board 50 when closed. Additionally, the circuit board 50 is supported and stabilized inside the adapter housing 38 by a plurality of screws 52 and standoffs 54. In the illustrated embodiment, the standoffs 54 are attached to the bottom cover 42 such that the circuit board 50 may be configured to sit on top of the standoffs 54, leaving space between the circuit board 50 and the inside surface of the bottom cover 42, thereby enabling heat dissipation within the welding gun adapter 20. The standoffs 54 are designed to receive and hold a respective screw 52. Accordingly, the circuit board 50 also includes screw holes established on the circuit board 50 at corresponding locations such that the screw holes are generally aligned with the standoffs 54. Screws 52 are inserted into the screw holes of the circuit board 50 and screwed into the standoffs 54 such that the circuit board 50 is secured between the screw heads and the standoffs 54, and secured to the bottom cover 42. In the illustrated embodiment, the standoffs 54 and screw holes are generally placed near the edges of the bottom cover 42 and at corresponding locations on the circuit board 50, respectively. In certain embodiments, the standoffs 54 and screw holes may be placed in various locations and be varied in number. In some embodiments, the standoffs 54 may be attached to the top cover 40 rather than the bottom cover 42, with the circuit board 50 being secured to the top cover 40 rather than the bottom cover 42. Additionally, in certain embodiments, the circuit board 50 may be disposed and secured within the adapter housing 38 in a manner different than that described above. For example, the circuit board 50 may be held by grooves along inside edges of the adapter housing 38, or held by clips, and so forth.
The top cover 40 and the bottom cover 42 may be joined together to encase the circuit board 50, as shown in
Regardless of the specific features of the adapter housing 38, it is noted that the welding gun adapter 20 is relatively simple in design, including a relatively small number of main components (e.g., the adapter housing 38, the circuit board 50 that includes the adapter circuit, the potentiometer 56 connected to the knob 48, the welder connector 44, and the welding gun connector 46). As such, the welding gun adapter 20 may be manufactured relatively inexpensively, while providing the valuable benefit of adapting welders that are not “spool gun ready” with spool guns, such as the 12V spool gun 14 described herein.
Referring now to
As described above, the welding gun adapter 20 includes four connections to the welder 12, two being the power input connections 68 as discussed above. The remaining two connections are trigger circuit connectors 76, which connect the welding gun adapter 20 to the welding gun trigger circuit of the welder 12. The adapter circuit 72 is also connected to the trigger circuit of the 12V spool gun 14 via the welding gun connector 46 (as illustrated in
The welding gun trigger circuit and the welder trigger circuit are coupled through circuitry in the adapter circuit 72 to form a system trigger circuit. As such, when the trigger 33 of the 12V spool gun 14 is activated, a trigger signal is transmitted from the 12V spool gun 14 to the welder 12. This allows the welder 12 to respond to the triggering of the 12V spool gun 14 by providing power, etc. In contrast with conventional welding gun trigger circuits which generally reference a control voltage common to detect triggering, the gun trigger circuit of the welding gun adapter 20 works from a simple contact closure. More specifically, to overcome the lack of control circuit voltage common, the optical isolator 74 is employed to sense current in the system trigger circuit, as opposed to trying to sense voltage. When the trigger 33 is depressed or activated in the 12V spool gun 14, the trigger signal is transmitted to the adapter circuit 72 via the gun trigger connectors 73, and the trigger circuit is closed. Current then flows from one terminal of the welder trigger receptacle (e.g., the trigger circuit connections 76) into the welding gun adapter 20, through a rectifying diode bridge 77, and through the optical isolator 74. As such, the connection is not polarity sensitive due to the rectifying diode bridge 77.
In certain embodiments, the optical isolator 74 includes a light-emitting diode and a photo-sensitive transistor. When current flows through the trigger circuit as a result of the gun trigger closure, the light-emitting diode lights, which bias the transistor on and turn the optical isolator 74 on. A gun trigger monitor toggles to an on state condition when the optical isolator 74 is turned on, as the 12V spool gun 14 has been triggered. Additionally, when the optical isolator 74 turns on, current flows through the device, energizing the motor control relay 64. When the motor control relay 64 is energized, the normally-closed contacts that are connected across the spool gun motor winding are opened, and the normally-open contacts are closed, connecting the adapter circuit 72 to the control common, which allows motor current to flow.
When the motor control relay 64 is de-energized, the normally-closed contacts that are connected across the spool gun motor winding are closed, and the normally-open contacts are opened, disconnecting the adapter circuit 72 from control common, halting the motor current. The normally-closed contact closure across the motor winding acts as a “dynamic brake” for the 12V spool gun motor 70, causing it to immediately stop with no coasting. This prevents the 12V spool gun 14 from sending excess welding wire to the weld puddle after power from the welder output 24 of the welder 12 has been removed.
The pulse width modulator 66 controls the voltage, and thus speed, of the 12V spool gun motor 70, which is also activated when the trigger circuit is enabled. The pulse width modulator 66 receives a reference voltage from the potentiometer 56, which outputs a voltage representing the desired motor speed as input by the user. The reference voltage from the potentiometer 56 is compared against a feedback voltage from the 12V spool gun motor 70 by an operational amplifier 78. An error signal is generated from the difference between the reference voltage and the feedback voltage, representing the difference between the desired speed of the 12V spool gun motor 70 and the actual speed of the 12V spool gun motor 70. The error signal is supplied to a compensation pin of the pulse width modulator 66. As the speed of the 12V spool gun motor 70 is determined by the feedback voltage, the pulse width modulator 66 regulates the voltage supplied to the 12V spool gun motor 70 such that the speed of the 12V spool gun motor 70 matches the desired speed. The pulse width modulator 66 regulates the 12V spool gun motor 70 such that all of the motor control voltage levels are below the weld output voltage level.
As such, the welding gun adapter 20 may provide the derived voltage to the 12V spool gun motor 70 of the 12V welding gun 14 using the welding arc voltage from the welder 12. In general, the welding gun adapter 20 is configured to receive the welding arc voltage (e.g., approximately 30 VDC) from the welder 12, and to output a lower derived voltage to the 12V welding gun 14, which may power the 12V spool gun motor 70. For example, in certain embodiments, approximately 17.6 VDC may be provided to the 12V welding gun 14.
Additionally, the functional elements of the welding gun adapter 20 as well as the circuit elements and layout of the welding gun adapter 20 as illustrated in
In certain embodiments, the voltage derived from the welding arc voltage of the welder 12 may be provided directly to the 12V spool gun 14, without the welding gun adapter 20. In other words, circuitry similar to that described above with respect to the welding gun adapter 20 may instead be located inside of the welder 12. The 12V spool gun motor 70 is rated at 12V, but may accept, as input, a derived voltage of approximately 15-30V, depending on the particular operating parameters of the 12V spool gun 14. Such an embodiment is depicted in
As described above, in certain embodiments, the welding system 10 provides a derived voltage (e.g., approximately 15-30 volts, or a maximum of approximately 17.6 volts) to the 12V spool gun 14, which may be used with conventional welders 12 without the need for a separate power supply to provide motor and control power. In certain embodiments, the 12V spool gun 14 may extract such motor and control power directly from the output welding voltage of the welder 12. In other embodiments, the 12V spool gun 14 may be used with the welding gun adapter 20 for powering the 12V spool gun motor 70 of the 12V spool gun 14 using weld power from the welder 12. The welding gun adapter 20 is configured to receive an input of the welding arc voltage, such as 30 VDC, from the welder 12, and to output a lower DC voltage (e.g., the derived voltage of approximately 15-30 volts, or a maximum of approximately 17.6 volts) to the 12V spool gun 14.
While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
This application is a Non Provisional patent application of U.S. Provisional Patent Application No. 61/467,457, entitled “12V Spool Gun”, filed Mar. 25, 2011, which is herein incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61467457 | Mar 2011 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13427677 | Mar 2012 | US |
| Child | 16044860 | US |
