HK1228839B - Weld head - Google Patents

Description

welding head

Technical Field

The invention relates to a welding head.

Background Art

A welding head is typically used to spot weld two or more metal parts, such as two overlapping sheet metal parts. The welding head typically includes a pair of opposing electrodes configured to apply pressure to clamp the parts together and to provide an electrical current through the parts. Alternatively, the welding head may include a pair of side-by-side electrodes configured to provide an electrical current through the parts. When the current passes through the electrodes, the electrical resistance provided by the parts tends to locally heat the parts around the contact point of the electrodes or at the mating surfaces of the parts, thereby locally melting the metal parts together to form a spot weld.

Additionally, conventional welding heads are designed to support a variety of different electrode configurations. Different electrode configurations can be selected depending on the desired spot weld size and the structure of the metal parts to be welded. However, removing and replacing electrodes on conventional welding heads can be cumbersome and time-consuming. Furthermore, because the electrodes must be installed on-site, accurate electrode alignment is difficult in conventional welding heads. Furthermore, some conventional welding heads are susceptible to temperature fluctuations, which can adversely affect the force output of the electrodes and, therefore, the quality of the resulting spot weld. Furthermore, conventional welding heads incorporate linear actuator motors to adjust the position of the electrodes. Because the strength of the magnets in the linear actuator motors varies along the stroke of the motor, such conventional welding heads are susceptible to variations in clamping force that are determined by the position of the linear actuator motor. Furthermore, when a conventional welding head is powered off, the electrodes tend to collide with each other, which can damage or prematurely wear the electrodes.

Summary of the Invention

The present disclosure relates to a welding head configured for spot welding two or more components. In one embodiment, the welding head includes a first electrode assembly configured to provide a welding current through the components and a second electrode assembly. The welding head also includes a linear actuator motor configured to drive the first electrode assembly to a desired position and apply a desired clamping force to the components. In one embodiment, the welding head includes an actuator arm connecting the linear actuator motor to an upper electrode assembly. The welding head also includes a temperature sensor connected to the linear actuator motor and configured to measure the temperature of a magnet housed within the linear actuator motor. The welding head also includes a controller configured to monitor the temperature measured by the temperature sensor. Based on the measured temperature, the controller is configured to adjust the current/voltage supplied to the linear actuator motor to maintain a desired clamping force. In one embodiment, the temperature sensor is a thermistor. In one embodiment, the first electrode assembly includes an upper adapter and a lower adapter detachably connected to the upper adapter. The lower adapter is configured to detachably receive the electrodes. In one embodiment, the welding head also includes a brake configured to move between an engaged position and a disengaged position. In the engaged position, the first electrode assembly is locked. In the disengaged position, the linear actuator motor is free to drive the position of the first electrode assembly. In one embodiment, the brake is configured to move to the disengaged position when power is supplied to the brake, and the brake is configured to move to the engaged position when power is removed from the brake or a user initiates an input command to the brake to a controller. In one embodiment, the brake includes a spring-loaded brake configured to engage and disengage a plurality of grooves in the actuator arm and a solenoid configured to actuate the spring-loaded brake.

The present disclosure also relates to a welding head comprising a first electrode assembly and a second electrode assembly configured to provide a welding current through a component. The welding head also includes a linear actuator motor housing a series of magnets. The linear actuator motor is configured to drive the first electrode assembly to a desired position and apply a desired clamping force to the component. The welding head also includes a linear encoder connected to the linear actuator motor. The linear encoder is configured to measure the position of the linear actuator motor. The welding head also includes a controller configured to monitor the position of the linear actuator motor measured by the linear encoder. The welding head also includes an algorithm programmed on the controller that correlates the position of the linear actuator motor with a force constant of the linear actuator motor. Based on the position of the linear actuator motor and the corresponding force constant of the linear actuator motor, the controller is configured to adjust the current provided to the linear actuator motor to maintain the desired clamping force. In one embodiment, the algorithm is a precalculated lookup table. In one embodiment, the linear encoder includes an optical sensor. In one embodiment, the first electrode assembly includes an upper adapter and a lower adapter removably connected to the upper adapter, wherein the lower adapter is configured to removably receive the electrode. In one embodiment, the welding head further comprises a brake configured to move between an engaged position in which the first electrode assembly is locked and a disengaged position in which the linear actuation motor is free to drive the position of the first electrode assembly.

The present invention also relates to a welding head comprising a first electrode assembly and a second electrode assembly configured to provide welding current through a component, a linear actuator motor configured to drive the first electrode assembly to a desired position and apply a desired clamping force to the component, an actuator arm connecting the linear actuator motor to the first electrode assembly, and a brake assembly configured to move between an engaged position and a disengaged position, wherein the position of the first electrode assembly is locked in the engaged position and the linear actuator motor is free to drive the position of the first electrode assembly in the disengaged position. In one embodiment, the brake assembly is configured to move to the disengaged position when power is supplied to the linear actuator motor and to move to the engaged position when power is removed from the linear actuator motor. In one embodiment, the brake is configured to move to the engaged position upon a user command to a controller. In one embodiment, the brake assembly comprises a brake having a plurality of teeth configured to engage and disengage a plurality of grooves in the actuator arm, a linear solenoid configured to drive the brake to the disengaged position, and a spring configured to bias the brake to the engaged position. In one embodiment, the welding head further comprises a shaft assembly having a first end connected to the brake and a second end connected to the linear solenoid.

This summary is provided to illustrate a selection of concepts, which will be further described in the detailed description below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to limit the scope of protection of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the welding head according to the present disclosure will be described with reference to the following drawings. The same reference numerals are used throughout the drawings to represent the same features or components. The drawings are not necessarily drawn to scale.

1 is a perspective view of a welding head including a housing and a pair of upper and lower electrode assemblies according to one embodiment of the present disclosure;

FIG2 is a perspective view of the welding head in FIG1 , wherein a portion of the housing is omitted to show the linear actuator motor and the brake housed in the housing;

FIG3 is an exploded perspective view of the upper electrode assembly in FIG1 ; and

4A and 4B are a perspective view and an exploded perspective view, respectively, of the brake in FIG. 2 .

DETAILED DESCRIPTION

The present disclosure relates to various embodiments of a welding head configured to spot weld two or more parts together by providing an electrical current through a pair of opposing electrodes pressed on opposite sides of the parts or a pair of side-by-side electrodes pressed against a surface of one or more of the parts. In addition, embodiments of the welding head of the present disclosure are configured to compensate for operating temperature variations or fluctuations within a linear actuation motor configured to urge the position of one or both electrodes. In addition, embodiments of the welding head are configured to compensate for variations in the magnetic field strength of a magnet housed in the linear actuation motor. Embodiments of the welding head of the present disclosure also include a brake configured to lock the position of the electrodes when the welding head is powered off, thereby preventing the electrodes from striking each other, which could otherwise damage or prematurely wear the electrodes.

Referring now to the embodiment shown in FIG1 , the welding head 10 includes a housing 11 configured to house a plurality of components, and an upper electrode assembly 12 and a lower electrode assembly 13, respectively, disposed outside the housing 11. As shown in FIG2 , the housing 11 houses a permanent magnet linear actuator motor 14 configured to urge the upper electrode assembly 12 into position, and a brake assembly 15 configured to lock the position of the upper electrode assembly 12 when the welding head 10 is powered off. The linear actuator motor 14 is configured to separate the upper electrode assembly 12 from the lower electrode assembly 13, allowing components of various sizes and shapes to be inserted between the upper electrode assembly 12 and the lower electrode assembly 13 and spot welded together. The linear actuator motor 14 is also configured to urge the upper electrode assembly 12 into position to provide a desired clamping force F to hold the components together during the welding operation.

In one embodiment, the permanent magnet linear actuator motor 14 includes a U-shaped magnet track 16 that supports first and second groups of magnets. The first and second groups of magnets face each other and are separated by a gap. The magnets in each of the first and second groups are arranged with their poles interleaved. The U-shaped magnet track 16 can be configured to support any desired number of magnets, such as, for example, 20 or more magnets. Furthermore, the linear actuator motor 14 includes a stator or forcer 17 having a plurality of windings or coils. The forcer 17 is positioned in the gap between the first and second groups of magnets and is configured to slide up and down along the magnet track 16 a maximum predetermined distance (i.e., the stroke of the linear actuator motor). Depending on the shape and size of the components adapted to the welding head 10, the linear actuator motor 14 can have any desired stroke, such as, for example, approximately 1 inch. The forcer 17 can be supported along the U-shaped magnet track by any suitable method, such as, for example, bearings or a track system. Although the linear actuation motor 14 is a U-channel linear motor in one embodiment, in one or more alternative embodiments, the welding head 10 may include any other suitable type of linear actuation motor, such as, for example, a cylindrical moving magnet linear motor or a flat linear motor.

The welding head 10 also includes an actuator arm 18 that protrudes outward from the housing 11. An upper end 19 of the actuator arm 18 is connected to the mover 17, and a lower end 20 of the actuator arm 18 is connected to the upper electrode assembly 12. Therefore, the linear actuator motor 14 is configured to push the position of the actuator arm 18, and thereby the position of the upper electrode assembly 12, based on the shape and size of the parts to be welded and the required clamping force F (i.e., the linear actuator motor 14 is configured to move the actuator arm 18 and the upper electrode assembly 12 up and down).

Continuing with reference to FIG. 2 , the welding head 10 further includes a temperature sensor 21, such as, for example, a thermistor or thermocouple, coupled to the linear motor 14 and configured to measure the temperature of magnets housed within the linear motor 14. The temperature of the magnets within the linear motor 14 affects the clamping force output F of the linear motor 14 (i.e., the clamping force F provided by the linear motor 14 is a function of the temperature of the magnets within the linear motor 14). Generally, the higher the temperature of the magnets within the linear motor 14, the lower the clamping force output F of the linear motor 14. The welding head 10 further includes a controller configured to monitor the temperature measured by the temperature sensor 21 and adjust the current supplied to the linear motor 14 based on the temperature of the magnets within the linear motor 14 to maintain a desired clamping force output F of the linear motor 14 (i.e., the controller is configured to compensate for temperature changes and fluctuations of the magnets within the linear motor 14 by adjusting the current supplied to the linear motor 14).

Continuing with FIG. 2 , the welding head 10 also includes a linear encoder 23 housed in the housing 11. The linear encoder 23 includes a sensor and a scale. The sensor is configured to measure the position of the mover 17 relative to the scale. The linear sensor 23 can include any suitable type of sensor, such as, for example, an optical sensor, a magnetic sensor, or an eddy current sensor. Furthermore, the controller is configured to compensate for variations in the magnetic field strength of the magnets in the linear actuator motor 14 as a function of the position of the mover 17 along its stroke. Small variations in the strength of the magnets in the linear actuator motor 14 affect the clamping force output F of the linear actuator motor 14. Generally, magnets of relatively higher strength produce greater clamping force F than magnets of relatively lower strength. In one embodiment, the controller is programmed with an algorithm (e.g., a pre-calculated lookup table) that correlates the force constant of the linear actuator motor 14 with the position of the mover 17 along its stroke. The lookup table can be generated by measuring the output force of the mover 17 at a series of discrete positions along its stroke. A linear interpolation method can be performed to determine the force constant of the linear actuator motor 14 for positions of the mover 17 that are not directly measured. Therefore, the controller is configured to monitor the position of the mover 17 as measured by the linear encoder 23 and reference an algorithm programmed on the controller (e.g., a pre-calculated lookup table) to determine the force constant of the linear actuator motor 14 at the current position of the mover 17. Based on the position of the mover 17 and the corresponding force constant of the linear actuator motor 14 at that position (determined by reference to the algorithm programmed on the controller (e.g., a pre-calculated lookup table)), the controller is configured to adjust the current supplied to the linear actuator motor 14 to maintain a desired clamping force F of the linear actuator motor 14 (i.e., the controller is configured to compensate for variations in the magnetic field strength of the magnets in the linear actuator motor 14 by adjusting the current supplied to the linear actuator motor 14 to maintain a constant, desired clamping force F of the welding head 10). Otherwise, the clamping force output F of the linear actuator motor 14 will vary along the stroke of the linear actuator motor 14.

Referring now to FIG. 3 , the upper electrode assembly 12 includes an upper mounting plate or adapter 24 and a lower mounting plate or adapter 25 removably connected to the upper adapter 24. The lower adapter 25 is configured to receive and support various electrodes 26 having different configurations depending on the structure of the parts to be spot welded together. For example, the lower adapter 25 can be configured to receive electrodes 26 having pointed, flat, hemispherical, and/or offset electrode tips. In normal operation, the upper adapter 24 is configured to remain connected to the lower end 20 of the actuator arm 18 (see FIG. 2 ), and the lower adapter 25 is configured to be detached from the upper adapter 24. Detaching the lower adapter 25 from the upper adapter 24 facilitates removal and replacement of the electrode 26 in a controlled environment (e.g., a workbench). Otherwise, removing and replacing the electrode 26 in situ (i.e., without removing the lower adapter 25) can be cumbersome and may result in misalignment between the electrode and the lower adapter 25, which can result in poor spot weld quality and may cause premature wear of the electrode 26. Once the desired electrode 26 has been mounted to the lower adapter 25 , the lower adapter 25 can be easily reconnected to the upper adapter 24 .

In the embodiment shown in FIG3 , the upper adapter 24 is a rectangular block having a pair of longer sides 27 and 28 extending in a longitudinal direction and a pair of shorter sides 29 and 30 extending transversely to the longer sides 27 and 28 . The upper adapter 24 also includes an inner surface 31 and an outer surface 32 opposite the inner surface 31 . In one or more alternative embodiments, the upper adapter 24 may have any other suitable shape, such as, for example, a square block. The upper adapter 24 also includes an opening 33, such as a smooth bore, extending between the longer sides 27 and 28 . The opening 33 is configured to receive a sleeve 34 (see FIG2 ) configured to electrically insulate the upper adapter 24 from the actuator arm 18 . The sleeve 34 may be constructed of any material suitable for electrically insulating the upper electrode assembly 12 from the actuator arm 18 , such as, for example, plastic, hard anodized aluminum, or ceramic. In the depicted embodiment, the sleeve 34 includes a cylindrical shank 35 and an annular head 36 located at the upper end of the shank 35 . The sleeve 34 also defines a central opening 37 and a slot 38 extending along the length of the central opening 37. A cylindrical shank 35 on the sleeve 34 is configured to be received in the opening 33 in the upper adapter 24, and an annular head 36 on the sleeve 34 is configured to rest on the longer side 27 of the upper adapter 24. The central opening 37 in the sleeve 34 is configured to receive a protrusion (not shown) on the lower end 20 of the actuator arm 18 to connect the upper adapter 24 to the actuator arm 18.

As shown in FIG3 , the upper adapter 24 also includes a slot 39 extending between the opening 33 and the shorter side 30. The slot 39 defines a pair of opposing legs 40 and 41. The legs 40 and 41 are configured to move between an uncompressed position, in which the legs 40 and 41 are spaced apart from each other, and a compressed position, in which the legs 40 and 41 abut each other. As the legs 40 and 41 move between the uncompressed and compressed positions, and between the compressed and uncompressed positions, the opening 33 in the upper adapter 24 is configured to contract and expand circumferentially about the cylindrical shank 35 of the sleeve 34, respectively. The upper adapter 24 also includes an opening 42 extending through the legs 40 and 41. The opening 42 is configured to receive a fastener 43, such as, for example, a socket head screw. Tightening the fastener 43 is configured to draw the legs 40 and 41 together, thereby contracting the opening 33 circumferentially about the sleeve 34. When the opening 33 in the upper adapter 24 is circumferentially contracted around the sleeve 34, the sleeve 34 is configured to circumferentially contract around the protrusion on the lower end 20 of the actuator arm 18 to connect the upper adapter 24 to the lower end 20 of the actuator arm 18. Conversely, loosening the fastener 43 is configured to pull the legs 40, 41 apart, thereby circumferentially expanding the opening 33 around the sleeve 34, thereby allowing the upper adapter 24 to be removed from the sleeve 34 and the lower end 20 of the actuator arm 18. Removing the upper adapter 24 from the actuator 18 can facilitate replacement or repair of the upper electrode assembly 12.

Continuing with FIG3 , upper adapter 24 further includes a pair of smooth blind bores 44, 45 extending upwardly from lower, longer side 28. One of smooth blind bores 44 is configured to receive a thin-walled cylindrical bushing 46, while the other smooth blind bore 45 is configured to receive an upper end 47 of a cylindrical retaining pin 48, the importance of which will be explained below. The thin-walled bushing 46 and retaining pin 48 can be received in blind bores 44 and 45, respectively, by any suitable means, such as, for example, threading, bonding, or press-fit (i.e., friction-fit).

In the embodiment shown in FIG3 , the lower adapter 25 is a block-shaped member having a pair of longer sides 49 , 50 extending in the longitudinal direction and a pair of shorter sides 51 , 52 extending transversely to the longer sides 49 , 50 . The lower adapter 25 also includes an inner surface 53 and an outer surface 54 opposite the inner surface 53 . In one or more alternative embodiments, the lower adapter 25 may have any other suitable shape, such as, for example, a square block. The lower adapter 25 also includes a pair of openings 55 , 56 extending downwardly from the upper longer side 49 . In the depicted embodiment, one opening 55 is a smooth blind hole, and the other opening 56 is a through-hole extending between the longer sides 49 , 50 of the lower adapter 25 . One opening 55 is configured to receive a locating pin 57 , while the other opening 56 is configured to receive a lower end 58 of a securing pin 48 . In the depicted embodiment, the locating pin 57 includes a cylindrical shank 59 and a diamond-shaped head 60 . The cylindrical shank 59 is configured to be received in the opening 55 in the lower adapter 25, and the diamond-shaped head 60 is configured to be received in the thin-walled bushing 46 in the upper adapter 24. In one embodiment, the cylindrical shank 59 is press-fitted into the opening 55 in the lower adapter 25, and the diamond-shaped head 60 is loosely or lightly interference-fitted into the bushing 46 in the upper adapter 24. Simultaneously, the locating pin 57 and the securing pin 48 are configured to ensure coaxiality between the upper and lower adapters 24, 25 when they are connected together. As will be described in detail below, the securing pin 48 is also configured to transmit electrode current from the upper adapter 24 to the electrode 26 supported by the lower adapter 25.

Continuing with FIG3 , the lower adapter 25 further includes a slot 61 extending between the opening 56 and the shorter side 52. The slot 61 defines a pair of legs 62, 63 configured to move between an uncompressed position, wherein the legs 62, 63 are spaced apart from each other in the uncompressed position, and a compressed position, wherein the legs 62, 63 abut each other in the compressed position. As the legs 62, 63 move between the uncompressed and compressed positions, and between the compressed and uncompressed positions, the opening 56 is configured to contract and expand circumferentially about the lower end 58 of the retaining pin 48, respectively. The lower adapter 25 further includes an opening 64, such as a through-hole, extending through the legs 62, 63. The opening 64 is configured to receive a fastener 65, such as, for example, a socket head screw. Tightening the fastener 65 is configured to draw the legs 62, 63 together, thereby contracting circumferentially about the lower end 58 of the retaining pin 48. In the circumferentially retracted position, the lower adapter 25 is detachably connected to the securing pin 48 and the upper adapter 24. Conversely, loosening the fastener 65 is configured to separate the legs 62, 63 and circumferentially expand the opening 56, thereby allowing the lower adapter 25 to be removed from the upper adapter 24 by sliding the lower adapter 25 downward until the securing pin 48 is disengaged from the opening 56. Removing the lower adapter 25 from the upper adapter 24 enables a user to remove and replace the electrode 26 supported by the lower adapter 25 in a controlled environment (e.g., a workbench), which allows the user to easily ensure that the electrode 26 is properly aligned with the lower adapter 25.

Lower adapter 25 also includes an opening 66, such as, for example, a through-hole extending between longer sides 49 and 50. Opening 66 is configured to selectively receive an electrode 26 having a desired configuration, depending on the structure of the parts to be welded and the desired spot weld size. Furthermore, lower adapter 25 includes a slot 67 extending between shorter side 51 of lower adapter 25 and opening 66. Slot 67 defines a pair of legs 68, 69 configured to move between an uncompressed position, in which legs 68, 69 are spaced apart from each other, and a compressed position, in which legs 68, 69 abut each other. As legs 68, 69 move between the uncompressed and compressed positions, and between the compressed and uncompressed positions, opening 66 is configured to contract and expand circumferentially about electrode 26, respectively, to allow electrode 26 to be installed and removed, respectively. Lower adapter 25 also includes an opening 70, such as a through-hole, extending through legs 68, 69. Opening 70 is configured to receive a fastener 71, such as, for example, a socket head screw. 6. Tightening the fasteners 71 is configured to draw the legs 68, 69 together, thereby circumferentially constricting the opening 66 around the electrode 26 to secure the electrode 26 to the lower adapter 25. Conversely, loosening the fasteners 71 is configured to pull the legs 68, 69 apart and circumferentially expand the opening 66, thereby allowing the electrode 26 to be removed from the lower adapter 25 by sliding the electrode 26 out of the opening 66. Additionally, in the depicted embodiment, the lower adapter 25 includes a notch 72 in the longer side 50 that defines a protrusion or projection 73 through which the electrode 26 extends. The notch 72 and projection 73 are configured to facilitate spot welding of components having various shapes and configurations. In one or more alternative embodiments, the lower adapter 25 may be provided without the notch 72 and projection 73.

Although only the upper electrode assembly 12 is described in detail above, it should be understood that the lower electrode assembly 13 may have the same or similar structure as the upper electrode assembly 12, so the lower electrode assembly 12 will not be described again to avoid repetition.

Referring now to the embodiment illustrated in Figures 2 and 3, the welding head 10 includes an input cable 74 electrically connected to the upper electrode assembly 12 and an output cable 75 electrically connected to the lower electrode assembly 13. Together, the cables 74 and 75 are configured to provide welding current to the electrodes 26 in the upper and lower electrode assemblies 12 and 13. The welding head 10 also includes a strap 76 electrically connecting the input cable 74 to the upper adapter 24. In the illustrated embodiment, the strap 76 is connected to the shorter side 30 of the upper adapter 24. The welding current can be any suitable current, such as, for example, approximately 5 Amps to approximately 4000 Amps, depending on the size and thickness of the parts to be welded and the desired size of the spot weld. The retaining pin 48 is configured to transmit the welding current from the upper adapter 24 to the lower adapter 25, and then to the electrodes 26. The retaining pin 48 can be constructed of any electrically conductive material, such as, for example, aluminum. Furthermore, as described above, the sleeve 34 is configured to electrically insulate the upper adapter 24 from the actuator arm 18, preventing the welding current from flowing into the actuator arm 18. Thus, welding current flows from the electrode 26 in the upper electrode assembly 12, through the set of parts to be welded, and then to the electrode 26 in the lower electrode assembly 13. As the current passes through the parts, the resistance offered by the parts tends to locally heat the parts around the contact point of the electrode 26, thereby locally melting the metal parts to form a spot weld joining the parts together.

4A and 4B , the brake assembly 15 will now be described in detail. The brake assembly 15 is configured to prevent the upper electrode assembly 12 from striking the lower electrode assembly 13 when power is removed from the linear actuating motor 14, such as upon completion of a subsequent spot welding operation. The brake assembly 15 can also be actuated by a user initiating a command to the controller. Otherwise, contact between the upper electrode assembly 12 and the lower electrode assembly 13 could damage or prematurely wear the electrode 26 (i.e., in the absence of the brake assembly 15, since the linear actuating motor 14 is oriented perpendicularly to the electrode assemblies 12 and 13, the upper electrode assembly 12 would fall downward and strike the lower electrode assembly 13 when power is removed from the linear actuating motor 14). In the depicted embodiment, the brake assembly 15 includes a mounting bracket 85 configured to mount the brake assembly 15 to the interior of the housing 11, as shown in FIG2 . The brake assembly 15 also includes a linear solenoid 86 and a shaft assembly 87, both of which are connected to the mounting bracket 85. The brake assembly 15 also includes a spring-loaded brake 88. As will be described in detail below, the spring-loaded brake 88 is configured to move between a disengaged position when power is supplied to the welding head 10 during a spot welding operation and an engaged position when the welding head 10 is de-energized after the spot welding operation is completed. In the disengaged position, the linear actuator motor 14 is free to drive the position of the upper electrode assembly 12 during the spot welding operation. In the engaged position, the brake assembly 15 is configured to lock the position of the upper electrode assembly 12 and prevent the upper electrode assembly from striking the lower electrode assembly 13.

In the embodiment shown in Figures 4A and 4B, mounting bracket 85 includes a base plate 89, a pair of support arms 90 and 91 projecting from base plate 89, and a flange 92 extending from outer ends of support arms 90 and 91 such that flange 92 is spaced apart from base plate 89. In the depicted embodiment, flange 92 is substantially parallel to base plate 89. Together, base plate 89, support arms 90 and 91, and flange 92 define a generally U-shaped mounting bracket 85. Base plate 89 includes a plurality of openings 93, such as, for example, four openings, configured to receive fasteners securing mounting bracket 85 to housing 11 of welding head 10, as shown in Figure 2. Base plate 89 of mounting bracket 85 also includes a pair of openings 94 configured to receive fasteners securing linear solenoid 86 to mounting bracket 85. Similarly, flange 92 of mounting bracket 85 includes a plurality of openings 95, such as, for example, two openings, configured to receive fasteners 96 securing shaft assembly 87 to mounting bracket 85. Flange 92 also includes an opening 97 configured to receive a portion of shaft assembly 87 , as described in detail below.

4A and 4B , the linear solenoid 86 includes a cylindrical housing 98 that houses a plunger 99 and a coil 100 wound around the plunger 99. The plunger 99 is configured to slide between an extended position and a retracted position (arrow 117). When current is supplied to the coil 100, the generated electromagnetic field tends to slide the plunger 99 into the retracted position within the cylindrical housing 98. When the current to the linear solenoid 86 is turned off, the plunger 99 is configured to return to the extended position, in which it protrudes outward from the cylindrical housing 98.

4A and 4B , the shaft assembly 87 includes a mounting plate 101 and a shaft 102 configured to slide between an extended position and a retracted position (arrow 118). The mounting plate 101 includes a pair of openings 103 for receiving fasteners 96 that secure the shaft assembly 87 to the flange 92 of the mounting bracket 85. When the shaft assembly 87 is connected to the mounting bracket 85, the shaft 102 extends through the openings 97 in the flange 92. The shaft 102 includes an inner end 104 configured to connect to the outer end 105 of the plunger 99 on the linear solenoid 86, and an outer end 106 opposite the inner end 104 configured to connect to the spring-loaded brake 88. The inner end 104 of the shaft 102 can be connected to the outer end 105 of the plunger 99 by any suitable means. In the depicted embodiment, a collar 107 is provided to connect the shaft 102 to the plunger 99. The collar 107 is a thin-walled cylindrical tube that is configured to slide over the inner and outer ends 104, 105, respectively, of the shaft 102 and the plunger 99. The collar 107 also includes a plurality of radial openings 108 configured to receive fasteners 109, such as set screws, that connect the collar 107 to the plunger 99 and the shaft 102.

As shown in Figures 4A and 4B, the brake 88 is a rectangular block having an outer surface 110 and an inner surface 111 opposite the outer surface 110. The brake 88 includes a plurality of openings 112, such as, for example, two openings, configured to receive fasteners 113 (e.g., set screws) that connect the brake 88 to the outer end 106 of the shaft 102. The outer surface 110 of the brake 88 includes a plurality of ridges or teeth 114. Although the brake 88 includes two teeth 114 in the illustrated embodiment, in one or more alternative embodiments, the brake 88 may have any other suitable number of teeth 114, such as, for example, from one to ten teeth 114. As described below, the teeth 114 on the brake 88 are configured to engage corresponding grooves 115 on the actuator arm 18, as shown in Figure 2, thereby preventing the electrode 26 on the upper electrode assembly 112 from striking the electrode on the lower electrode assembly 13 when the linear actuator motor 14 is de-energized. The brake assembly 15 further includes a spring 116 disposed between the inner surface 111 of the brake 88 and the mounting plate 101 on the shaft assembly 87 . The significance of the provision of the spring 116 will be explained below.

In operation, the brake 88 is configured to move between an engaged position and a disengaged position (arrow 119). When current is supplied to the linear solenoid 86, the plunger 99 is configured to move (arrow 117) to a retracted position. In addition, since the plunger 99 is connected to the shaft 102 by the collar 107, the retraction of the plunger 99 is configured to pull the shaft 102 to the retracted position (i.e., the shaft 102 slides (arrow 118) to the retracted position). In addition, the retraction of the plunger 99 is configured to provide a force large enough to overcome the biasing force of the spring 116, so that the brake 88 slides (arrow 119) to the disengaged position and compresses the spring 116 (i.e., the retraction of the plunger 99 and the shaft 102 is configured to drive the brake 88 into the disengaged position). In the disengaged position, the teeth 114 on the brake 88 are disengaged from the corresponding grooves 115 in the actuator arm 18 (see FIG. 2 ), allowing the linear actuator motor 14 to freely drive the actuator arm 18 and the upper electrode assembly 12 to the desired position. Thus, the brake 88 is in the disengaged position during the spot welding operation.

When power is removed from the linear solenoid 86, such as after a spot welding operation is completed, the electromagnetic force pulling the plunger 99 and the shaft 102 to their retracted positions is eliminated, and thus the biasing force of the spring 116 is configured to return the brake 88 to the engaged position (i.e., when the linear solenoid 86 is de-energized, the spring 116 is configured to bias the brake 88 to the engaged position). In the engaged position, engagement between the teeth 114 on the brake 88 and the grooves 115 in the actuator arm 18 is configured to lock the position of the actuator arm 18 and the upper electrode assembly 12, thereby preventing the upper electrode assembly 12 from falling and striking the lower electrode assembly 13, as shown in FIG2. In addition, the spring 116 is configured to return the shaft 102 and the plunger 99 to their initial extended positions (i.e., when the linear solenoid 86 is de-energized, the biasing force provided by the compressed spring 116 forces the plunger 99 and the shaft 102 to slide 117 and 118, respectively, back to their extended positions). Thus, the shaft 102 and plunger 99 can then be driven back to their retracted positions to disengage the brake 88 by providing power to the linear solenoid 86 so that the linear actuator motor 14 can freely advance the position of the upper electrode assembly 12 during subsequent spot welding operations.

Although the present invention has been described in detail with reference to the above-mentioned exemplary embodiments, the exemplary embodiments described herein are not intended to be exhaustive or to limit the scope of the invention to the precise form disclosed. Those skilled in the art and technology to which the present invention pertains will appreciate that changes and modifications may be made to the described structures and methods of assembly and operation without departing from the principles, spirit, and scope of the invention as described in the following claims. Although relative terms such as "outside," "inside," "upper," "lower," "below," and "above" and similar terms have been used herein to describe the spatial relationship of one element to another, it should be understood that these terms are intended to encompass different orientations of the various elements and components of the device in addition to the orientations shown in the accompanying drawings. In addition, the terms "substantially," "approximately," and similar terms used herein are used as approximate terms rather than terms of degree, and are used to illustrate inherent deviations in measurements or calculations that are understood by those skilled in the art.

Claims (3)

1. A welding head configured for spot welding two or more components together, the welding head comprising: A first electrode assembly and a second electrode assembly are configured to provide welding current through the component; A linear actuation motor, comprising a fixed magnet and a movable actuator, the linear actuation motor being configured to drive the first electrode assembly to a desired position and apply a desired clamping force to the assembly; A temperature sensor, connected to the linear actuation motor and configured to measure the temperature of the magnet of the linear actuation motor; A controller is configured to monitor the temperature measured by the temperature sensor, and the controller adjusts the current supplied to the linear actuation motor according to the temperature to maintain the desired clamping force. An actuating arm, which connects the linear actuating motor to the first electrode assembly; and A brake configured to move between an engaged position and a disengaged position, wherein the position of a first electrode assembly is locked in the engaged position, and the linear actuation motor is free to drive the position of the first electrode assembly in the disengaged position, the brake comprising: A spring-loaded brake, the spring-loaded brake being configured to engage and disengage from a plurality of grooves in the actuating arm; and A solenoid, configured to drive a spring-loaded brake. Wherein, the brake is configured to move to the disengaged position when power is supplied to the brake, and The brake is configured to move to the engagement position when the brake is de-energized. 2. The welding head according to claim 1, wherein the temperature sensor is a thermistor. 3. The welding head according to claim 1, wherein the first electrode assembly comprises: Up adapter; and A lower adapter, which is detachably connected to the upper adapter, wherein the lower adapter is configured to detachably receive electrodes.