Patent Application
20130193126
The invention relates generally to wire feeders and, more particularly, to a motorized wire spool for a wire feeder.
Welding is a process that has become increasingly ubiquitous in various industries and applications. While such processes may be automated in certain contexts, a large number of applications continue to exist for manual welding operations. Such welding operations rely on a variety of types of equipment to ensure the supply of welding consumables (e.g., wire feed, shielding gas, etc.) is provided to the weld in an appropriate amount at the desired time. For example, metal inert gas (MIG) welding typically relies on a wire feeder to ensure a proper wire feed reaches a welding torch. MIG welding also relies on gas-channeling tubes or cables for routing shielding gas to the torch during the time a welding arc is created between the wire and a workpiece.
Wire feeders are used to provide welding wire to a welding torch. Generally, when a torch trigger is actuated, the wire feeder provides welding wire and, when the torch trigger is released, the wire feeder stops providing welding wire. Rollers within the wire feeder pull welding wire from a wire spool to provide the welding wire to the welding torch. Often, one or more of the rollers is motorized in order to pull the welding wire from the spool. When a welding operator initiates a welding arc using the welding torch, the rollers are rotated quickly to provide welding wire to the welding torch. Thus, the motorized roller accelerates rapidly in an attempt to meet the demands of the welding torch. Unfortunately, the motorized roller may not provide welding wire within a desired amount of time.
When the welding operator terminates a welding arc, the rollers quickly stop. As will be appreciated, when this happens the momentum of the wire spool may cause it to continue to rotate. To inhibit the wire spool from rotating at undesirable times, the wire spool may use mechanically or electrically powered brakes to stop the wire spool, such as when the welding arc is terminated. Unfortunately, the brakes may place a constant drag on the wire spool, even when rotation is desired, in order to be able to stop the wire spool quickly. As a result, the roller motor is inclined to provide additional rotational energy to overcome the drag placed on the wire spool by the brakes.
When a welding torch trigger is actuated and delivery of welding wire is demanded, the roller motor accelerates the wire spool to a desired operating speed by pulling directly on the wire. As will be appreciated, the amount of force applied by the roller motor varies with the weight of the spool of wire (e.g., the force depends on whether the spool is full, nearly empty, or somewhere in-between). Further, the total force applied by the roller motor to turn the spool is a combination of the forces necessary to overcome friction, to overcome brake drag, and to accelerate the mass of the spool. As such, the total force to turn the spool is directly correlated to the distance from the surface of the wire on the spool to the rotational axis of the spool. For example, the distance from the surface of the wire on the spool to the rotational axis of the spool diminishes as the wire is consumed during a welding application. Consequently, due to the decreasing volume of wire on the spool, the pulling force needed to accelerate the mass of the wire and spool decreases. However, the pulling force on the wire needed to overcome friction and brake drag increases due to a decrease in the leverage used to rotate the spool, thereby increasing the total force needed to rotate the spool. Accordingly, there exists a need for wire feeders that overcome such disadvantages.
In one embodiment, a wire feeder includes a wire spool motor configured to rotate a wire spool. The wire feeder also includes a motor control assembly configured to control rotation of the wire spool motor. The motor control assembly includes a control arm and a biasing member. The biasing member being configured to exert a force on the control arm to direct the control arm away from a forward control position. The wire feeder includes an enclosure housing the wire spool motor and the motor control assembly.
In another embodiment, a method for feeding welding wire from a wire feeder includes rotating a wire roller motor in a first direction in response to initiation of a wire welding application to provide welding wire to the welding application. The method also includes adjusting a position of a control arm to a forward control position after the wire roller motor begins rotating. The position of the control arm is adjusted to the forward control position when a first force applied to the control arm by the welding wire is greater than a second force applied to the control arm by a biasing member. The method includes rotating a wire spool motor to provide welding wire after the control arm adjusts to the forward control position.
In another embodiment, a wire tensioner assembly for a wire feeder includes a wire spool motor configured to rotate a wire spool. The wire tensioner assembly also includes a motor control assembly configured to control rotation of the wire spool motor. The motor control assembly includes a control arm and a biasing member. The biasing member being configured to exert a force on the control arm to direct the control arm away from a forward control position.
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:
Turning now to the figures,
The welding system 10 also includes a wire feeder 30 that provides welding wire to the welding torch 16 for use in the welding operation. The wire feeder 30 may include a control panel 32 that allows the user to set one or more wire feed parameters, such as wire feed speed. Additionally, the wire feeder 30 may house a variety of internal components, such as a wire spool, a spool motor, a motor control assembly, rollers, a roller motor, and so forth. These internal components may be configured to provide welding wire to the welding torch 16 in a more efficient manner than in other systems. For example, the wire feeder 30 may include the spool motor coupled to the wire spool. The spool motor is controlled by the motor control assembly. The motor control assembly and spool motor work together to provide tension to the welding wire. Specifically, the motor control assembly controls whether, and in what direction, the spool motor rotates. As such, the motor control assembly and the spool motor eliminate the need for electrically and/or mechanically controlled brakes attached to the wire spool. Further, the motor control assembly acts as an accumulator to aid the roller motor in quickly providing welding wire to a welding application. Using such devices, the wire feeder 30 may overcome deficiencies found in other wire feeders. As will be appreciated, the wire feeder 30 may be used with any wire feeding process, such as gas operations (gas metal arc welding (GMAW)) or gasless operations (shielded metal arc welding (SMAW)). For example, the wire feeder may be used in metal inert gas (MIG) welding or tungsten inert gas (TIG) welding.
A variety of cables and conduits couple the components of the welding system 10 together and facilitate the supply of electrical power and welding materials to the welding torch 16. A first cable 34 couples the welding torch 16 to the wire feeder 30. A second cable 36 couples the welding power supply 12 to a work clamp 38 that connects to a workpiece 40 to complete the circuit between the welding power supply 12 and the welding torch 16 during a welding operation. A bundle 42 of cables and conduits couples the welding power supply 12 to the wire feeder 30 and provides weld materials for use in the welding operation. The bundle 42 includes a welding power cable 44, a gas hose 46, and a control cable 48. The control cable 48 may be any suitable type of control cable. It should be noted that the bundle 42 of cables and conduits may not be bundled together in some embodiments.
It should be noted that modifications to the welding system 10 of
A wire tensioner assembly 64 is used to provide tension to the welding wire 54. Specifically, the wire tensioner assembly 64 maintains tension on the welding wire 54 between the wire spool 52 and the rollers 56 and 58. The wire tensioner assembly 64 includes a wire spool motor 66. The wire spool 52 is coupled to the wire spool motor 66 and the wire spool motor 66 rotates the wire spool 52 during operation of the wire feeder 30. The wire spool motor 66 may rotate in either a clockwise or a counter-clockwise direction. In the present embodiment, the wire spool motor 66 rotates the wire spool 52 in a counter-clockwise direction to aid in unwinding welding wire 54 from the wire spool 52. As illustrated, if the wire spool motor 66 rotates the wire spool 52 in a clockwise direction, welding wire 54 is wound onto the wire spool 52. As will be appreciated, the wire spool 52 may be installed in a reversed position so that rotation in the clockwise direction aids in unwinding welding wire 54 from the wire spool 52, and rotation in the counter-clockwise direction winds welding wire 54 onto the wire spool 52.
The wire tensioner assembly 64 also includes a motor control assembly 68. The motor control assembly 68 controls the rotation of the wire spool motor 66. As illustrated, the motor control assembly 64 includes a control arm 70 coupled to a hub 72 via a fastener 74. A central portion of the control arm 70 is rotatably mounted to the hub 72. The hub 72 may include various electrical and/or mechanical devices. For example, the hub 72 may include a potentiometer (or another suitable device for providing feedback based on a position) and/or a biasing member. The potentiometer may be used to provide a control signal from the motor control assembly 64 to the wire spool motor 66 to control whether the spool motor 66 rotates in a forward direction, rotates in a reverse direction, or does not rotate. Further, the potentiometer may be used to determine a rate of rotation of the wire spool motor 66 (e.g., further rotation of the potentiometer results in a faster rate).
The biasing member is used to exert a force on the control arm 70 to direct the control arm 70 away from a forward control position (e.g., position of the control arm 70 that directs forward rotation of the spool motor 66). Further, the biasing member may direct the control arm 70 toward a neutral control position (e.g., position of the control arm 70 that directs no rotation of the spool motor 66) and/or a reverse control position (e.g., position of the control arm 70 that directs reverse rotation of the spool motor 66). The biasing member also is used to control a wire tension between the rollers 56 and 58 and the wire spool 52. As will be appreciated, the biasing member may include a linear potentiometer, rotary potentiometer, torsion spring, linear spring, air cylinder, and so forth.
The hub 72 may act as a pivot or rotational axis for the control arm 70. As illustrated, the axis of the control arm 70 is generally parallel to a rotational axis of the spool motor 66. A wire guide 76 (e.g., pulley) is coupled to the control arm 70 on a first end via a fastener 78. The wire guide 76 is used to route the welding wire 54 to the rollers 56 and 58. In certain embodiments, the wire guide 76 may have a diameter of approximately 3 to 7 inches. Further, a counter weight 80 is coupled to the control arm 70 on a second end via a fastener 82. The counter weight 80 provides a weight to balance the weight of the wire guide 76 so that the wire feeder 30 will operate properly even if the wire feeder 30 is not on a level surface. For example, the counter weight 80 may make it so the wire feeder 30 will operate properly on its side, or upside down. Further, the counter weight 80 aids in balancing the control arm 70 and the biasing member to cause the control arm 70 to be neutral to the force of gravity such that the mechanical functioning of the assembly is unaffected by the orientation of the wire feeder 30.
The welding wire 54 extends off of the wire spool 52, around the wire guide 76, and through the rollers 56 and 58. As will be appreciated, the motor control assembly 68 is used to apply a tension force onto the welding wire 54. For example, the motor control assembly 68 may provide a constant back pressure (e.g., force) against the welding wire 54 of approximately 6 ounces. The back pressure may be adjustable for tailoring the wire feeder 30 to the needs of a particular welding application. The tension applied by the motor control assembly 68 aids in eliminating slack in the welding wire 54. In certain embodiments, the motor control assembly 68 (e.g., using the biasing member) may exert a back pressure that varies within a predetermined range during operation. For example, the motor control assembly 68 may exert a back pressure that varies between approximately 4 and 10 ounces.
At block 122, the control arm 70 is adjusted to a reverse control position (e.g., as a result of force being applied to the control arm 70, such as by the biasing member 99). Then, at block 124, the spool motor 66 is rotated in a second direction 124 (e.g., as a result of the control arm 70 being moved to the reverse control position). By rotating in the second direction 124 (e.g., reverse), the spool motor 66 applies force to the control arm 70 by the welding wire 54 to counter the force applied to the control arm 70 by the biasing member 99. The spool motor 66 also adjusts the position of the control arm 70 to a stationary position (e.g., a position where the control arm 70 has little or no movement and held in place by the spool motor 66 rotating in the second direction 124). Thus, the spool motor 66 provides a predetermined wire tension to the welding wire 54. As will be appreciated, the blocks of the method 108 may be arranged in a different order than presented, and the method 108 may contain fewer or more steps than described. With such a method, the wire tensioner assembly 64 is able to maintain tension on the welding wire 54 to inhibit wire loops from coming off the wire spool 52 and into the wire feeder 30. Further, by using the wire tensioner assembly 64 to replace electrical or mechanical braking, the roller motor 60 may be smaller than in systems that use the braking (due to the constant load placed on the wire spool 52 by the braking). In addition, by using the wire tensioner assembly 64 to motorize the wire spool 52, the roller motor 60 may be smaller because it is not used to accelerate the mass of the wire spool 52 up to operating speed. Further, by using the wire tensioner assembly 64, the rollers 56 and 58 may exert less pressure against the welding wire 54 to feed the welding wire 54 to a welding application resulting in less degradation in the quality of the welding wire 54 and less debris falling off the welding wire 54. As such, the wire tensioner assembly 64 overcomes various deficiencies found in certain wire feeding systems.
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.
