Spot welding device

Abstract

Spot welding device (1), comprising: An up-down movement unit (5) including a slide block provided on one side of an arm of a robot to move vertically by the operation of an actuator (29); an upper welding gun (7) mounted on the slide block, the upper welding gun (7) including a first welding tip (23) projecting in a longitudinal direction of a front end of the arm and a second welding tip (25) projecting in a downward direction to the longitudinal direction; a left-right movement unit (9) installed on one side of the upper welding gun (7) for horizontally moving the upper welding gun (7) by actuating the actuator (29); and a lower welding gun (11) supported to correspond to a lower side of the upper welding gun (7).

Description

Background of the invention(a) Field of the invention

[0001] The present invention relates to a spot welding apparatus, and more particularly to a spot welding apparatus which performs welding by selecting an X-type or a C-type which matches a welding spot of a welding target to be universally applied to various vehicle models, and which enables rapid welding in a limited space with a minimum amount of time. (b) Description of the related art

[0002] Generally, during a vehicle manufacturing process, various structural parts, such as a press-formed vehicle body panel and the like, are joined by a process such as welding to complete an integrated vehicle body. The completed vehicle body is painted, and rust preventative is applied over the entire surface of each part in a painting process. Afterward, a finishing process is performed, such as assembling a part of a powertrain system and parts such as a suspension, steering, and braking system, and then assembling a door, trunk lid, hood, and the like.

[0003] Furthermore, in a vehicle body manufacturing process of the vehicle, spot welding by means of a spot welding machine is sometimes used as a method for joining two vehicle body panels such as a roof, a pillar, a side panel, an opening unit flange, a vehicle body door, and the like.

[0004] Resistance spot welding is a process in which contacting metal surfaces are joined by heat derived from the resistance of an electric current. As such, the weld is typically made by holding the workpieces together under pressure applied by electrodes mounted on a spot welding jig at the front end of an arm of a spot welding robot.

[0005] A spot welding device that selectively uses the X-type welding gun, the C-type welding gun, and the special-type welding gun is installed via an arm of a robot. As a result, a first robot in which the first spot welding device that uses the X-type welding gun is installed, a second robot in which a spot welding device that uses the C-type welding gun is installed, and a third robot in which a spot welding device that uses the special-type welding gun is installed are separately installed to achieve the appropriate spot welding operation.

[0006] However, in an ordinary spot welding process, only one spot is welded when the robot arm moves because a spot welding device is installed in the robot arm for each robot, and as a result, a long time is required to perform the predetermined number of spot welding processes, thereby reducing productivity and efficiency.

[0007] Furthermore, lower welding guns of different shapes need to be adjusted according to the position and shape of the welding spot, resulting in increased building investment costs. In particular, when multiple robots are mounted on a spot welding machine using a lower welding gun with a special shape, building and maintenance costs increase, and energy consumption is excessive. Furthermore, the space occupancy rate of the robot in a mass production line also increases.

[0008] JP 2 715 577 B2 describes a spot welding device for body floor panels, wherein an inclined and a horizontal part of a body floor panel are positioned in a positioning device by means of robot arms and welded with bolt guns.

[0009] US 6 337 456 B1 describes a resistance welding machine with an arm, a drive unit and a welding unit, which are mounted and removed by a gun mount on a robot and / or individually as a unit with a common base or a rail main body. Summary

[0010] The present invention was made in an effort to provide a spot welding apparatus which performs welding while changing a type of welding gun according to different welding spots of a welding target, to be universally applied to various vehicle models, and to perform the welding operations quickly in a limited space with a minimum amount of time, to increase productivity, flexibility and efficiency of a vehicle body process, and to reduce the number of robots by one application of one apparatus, and to secure installation costs.

[0011] The present invention provides a spot welding apparatus including: an up-and-down moving unit including a slide block provided on one side of an arm of a robot to move vertically by an operation of an actuator; an upper welding gun supported on the slide block, the upper welding gun including a first welding tip protruding in a longitudinal direction of a front end of the arm and a second welding tip protruding in a downward direction to the longitudinal direction; a left-and-right moving unit installed on one side of the upper welding gun to horizontally move the upper welding gun by an operation of the actuator; and a lower welding gun supported to correspond to a bottom side of the upper welding gun.The up-down movement unit can be supported by a separate bracket which is mounted on the arm of the robot.

[0012] The lower welding gun may include a third welding tip provided vertically and corresponding to a front end of the arm and the second welding tip, and a fourth welding tip projecting horizontally to the third welding tip and in an opposite direction to the first welding tip, respectively.

[0013] The up-down movement unit may include a body installed vertically on the clamp, a drive motor installed at a lower end of the body, and a slider provided to move vertically on a screw shaft installed in the body and rotated by an operation of the drive motor and supported on the upper welding gun.Additionally, in some embodiments, the left-right movement unit includes a gear box provided on one side of the upper welding gun, an actuator installed on one side of the gear box parallel to the upper welding gun, and a movement block provided to reciprocate a screw shaft installed on another side of the gear box parallel to the actuator and rotated by receiving the operation of the actuator by the gear box and connected to the upper welding gun.

[0014] The drive motor can be designed as a stepper motor whose revolutions per minute and direction of rotation are controllable.

[0015] A power line unit that conducts current may be installed on one side of the upper welding gun and the lower welding gun. This power line unit may conduct current to the upper welding gun from a transformer installed on a lower side of the lower welding gun via a busbar and a shunt.

[0016] More specifically, in some exemplary embodiments of the present invention, the first and second welding tips of the upper welding gun may be spaced approximately 90° apart from each other. Similarly, the third and fourth welding tips of the lower welding gun may be spaced approximately 90° apart from each other.

[0017] A rotating unit that rotates the upper welding gun and the lower welding gun on the clamp can also be installed on one side of the clamp. Alternatively or additionally, the rotating unit can be implemented as a rotating motor installed on one side of the clamp. This rotating motor can be implemented as a stepper motor whose rotational speed and direction of rotation are controllable.

[0018] Advantageously, according to the exemplary embodiments of the present invention, a welding operation is performed while changing the type of an upper welding gun according to the different welding points of a welding target in order to perform a rapid welding operation in a limited space during a minimum amount of time.

[0019] Furthermore, the spot welding apparatus can be universally applied to a variety of vehicle models, regardless of the vehicle model, the position, and the shape of a welding spot. A rapid welding process is provided by the exemplary embodiment of the present invention to improve the productivity, flexibility, and efficiency of a vehicle body process. In addition, the number of robots installed in a production line can be reduced by using one apparatus, thus saving on building investment costs. Short description of the characters Fig. 1 is a perspective view of a spot welding apparatus according to an exemplary embodiment of the present invention. Fig. 2 is a perspective view of an up-down moving unit of the spot welding apparatus according to the exemplary embodiment of the present invention. Fig. 3 is a perspective view of a left and right moving unit of the spot welding apparatus according to the exemplary embodiment of the present invention. Fig. 4 is a perspective view of an operation of a rotating unit of the spot welding apparatus according to the exemplary embodiment of the present invention. Fig. 5-8 are operation state diagrams of the spot welding apparatus according to the exemplary embodiment of the present invention. Detailed description of the embodiments

[0020] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention in any way. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It is further to be understood that the terms "comprises" and / or "comprising," when used in this specification, indicate the presence of recited features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the related listed items.

[0021] Unless expressly stated or clear from the context, the term "about" as used herein should be understood as being within a range of tolerances normal in science, for example, within 2 standard deviations of the mean. "About" can be understood as being within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05% or 0.01% of the stated value. Unless otherwise clear from the context, all numerical values stated herein are deemed to include the term "about".

[0022] Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying figures. However, since the size and thickness of each of the components in the drawings are expressed arbitrarily, the present invention is not specifically limited to the size and thickness shown in the drawings, and the thickness is exaggerated to clearly illustrate various parts and areas.

[0023] Parts not related to a description have been omitted in order to clearly describe the exemplary embodiments of the present specification, and the names of the elements in the following description are distinguished into first, second, and the like to distinguish the elements, since the names of the elements are the same and are not particularly limited by an order thereof.

[0024] However, in the description of an exemplary embodiment of the present invention, a spot welding apparatus 1 according to an exemplary embodiment of the present invention performs a welding operation by changing the type of a welding gun between an X-type and a C-type to correspond to different welding points of a welding target.

[0025] As a result, the spot welding apparatus 1 according to the exemplary embodiment of the present invention can be universally applied to various vehicle models and can quickly perform a welding process in a limited space with a minimum amount of time to improve productivity, flexibility, and efficiency of a vehicle body process, and reduce the number of robots by using one apparatus to secure installation costs.

[0026] Fig. 1 is a perspective view of a spot welding apparatus according to an exemplary embodiment of the present invention. With reference to Fig. 1, a spot welding apparatus 1 according to an exemplary embodiment of the present invention includes a clamp 3, an up-down moving unit 5, an upper welding gun 7, a left-and-right moving unit 9, and a lower welding gun 11. The clamp 3 may include a fork-shaped body 13, and has a supporting portion (not shown) supported on an arm of a robot provided on one side thereof.

[0027] The up-down movement unit 5 may be mounted on one side of the body 13 of the clamp 3 to vertically move the upper welding gun 7 by means of a slider 17 which moves vertically.

[0028] Fig. 2 is a perspective view of an up-down movement unit of the spot welding apparatus according to the exemplary embodiment of the present invention. Referring to Fig. 2, the up-down movement unit 5 includes a vertical frame 19, a drive motor 21, and the slider 17. The vertical frame 19 is vertically installed in the body 13 of the clamp 3 and has a screw shaft (not shown) installed therein. Additionally, the drive motor 21 is installed at a lower end of the vertical frame 19 to rotate the screw shaft.

[0029] In this case, the drive motor 21 can be designed as a stepper motor whose revolutions per minute and direction of rotation are controllable.

[0030] The slider 17 may be installed on the screw shaft to be vertically movable, and as a result, the upper welding gun 7 is supported thereon. Therefore, the upper welding gun 7 is moved vertically while the slider 17 is moved vertically according to an operation of the drive motor 21. The upper welding gun 7 is therefore preferably supported on the up-down moving unit 5 by the slider 17, as described above.

[0031] Additionally, the upper welding gun includes a first welding tip 23 and a second welding tip 25 provided at a front end of the arm. The first welding tip 23 is provided to protrude in a longitudinal direction of the arm, and the second welding tip 25 is provided to protrude downward toward the first welding tip 23. In this case, the first welding tip 23 and the second welding tip 25 may be spaced apart from each other by approximately 90°. The up-down moving unit 9 may be installed on one side of the upper welding gun 7 to horizontally move the upper welding gun 7.

[0032] Fig. 3 is a perspective view of a left and right movement unit of the spot welding apparatus according to the exemplary embodiment of the present invention. Referring to Fig. 3, the left and right movement unit 9 includes a gear 27, an actuator 29, and a movement block (not shown).

[0033] The gear 27 may be provided perpendicular to the upper welding gun 7 on an opposite side, with the first and second welding tips 23 and 25 being provided to the upper welding gun 7. The actuator 29 is installed parallel to the upper welding gun 7 on one side of the gear 27. The movement block may be installed on another side of the gear housing 27 through a housing 14, and may be configured to receive actuation of the actuator 29 via the gear 27 to reciprocate horizontally on the screw shaft (not shown), rotating the screw shaft in the housing 14.

[0034] Here, the upper welding gun 7 is mounted on the movement block, and the upper welding gun 7 is moved vertically by actuating the actuator 29 during the welding process. More specifically, the actuator 29 can be designed as a roller screw actuator that converts the torque of an electric motor into a linear motion.

[0035] The actuator rotates the screw shaft (not shown) which is positioned parallel to the actuator 29 through the gear housing 27, and as a result, the movement of the moving block 31 is converted into the linear movement on the screw shaft to horizontally reciprocate the upper welding gun 7.

[0036] The roller screw actuator has a conventional configuration in which a nut-like moving block, which engages a thread of a screw shaft, moves forward and backward, while the screw shaft, which is connected to the drive shaft of an electric motor, is rotated by the motor drive force. Therefore, since a configuration of the roller screw actuator that can be used as an actuator is a well-known configuration widely used in industries, a detailed description thereof will be omitted.

[0037] Meanwhile, the lower welding gun 11 is mounted on a lower side of the upper welding gun 7 to correspond to each other. In addition, the lower welding gun 11 includes a third welding tip 33 and a fourth welding tip 35, which correspond to the first and second welding tips 23 and 25 of the upper welding gun 7, provided at the front end of the arm.

[0038] The third welding tip 33 is provided vertically at the front end of the arm to correspond to the second welding tip 25 of the upper welding gun 7. The fourth welding tip 35 is provided to protrude parallel to the third welding tip 33 and in an opposite direction to the first welding tip 23 of the upper welding gun 7. In this case, the third welding tip 33 and the fourth welding tip 35 may be provided spaced 90° apart from each other.

[0039] Meanwhile, a power line unit 37 may be installed on either side of the upper welding gun 7 and the lower welding gun 11. This power line unit 37 may include a transformer 39, a bus bar, and a shunt. The transformer 39 may be installed on a lower side of the lower welding gun 11, and the bus bar and the shunt are installed on one side of the transformer 39 in this case to allow power to be supplied to the upper welding gun 7 and the lower welding gun 11. Here, the shunt may be connected to the body 13 of the clamp 3, the transformer 39, and the upper and lower moving units 5 to allow power to be supplied therethrough.

[0040] It should be noted, however, that the current line inlet 37 installed in the spot welding device 1 has a known function which is widely used in the art, and a more detailed description thereof will therefore be omitted.

[0041] Furthermore, reference numerals 41 and 43 in the figures represent a frame that fixes the transformer 39 to the clamp 3. A rotating unit 45 that rotates the upper welding gun 7 and the lower welding gun 11 toward the clamp 3 may be installed on one side of the body 13 of the clamp 3.

[0042] Fig. 4 is a perspective view of an operation of a rotating unit of the spot welding apparatus according to the exemplary embodiment of the present invention. Referring to Fig. 4, the rotating unit 45 may be configured as a rotating motor 47, and since the rotating motor 47 is installed through the body 13 of the clamp 3 to be operated, all components except the clamp 3 are rotated.

[0043] In this case, a drive shaft in the rotation motor 47 may be installed on the bracket 3 above the body 13 of the bracket 3 and directly connected to the components connected to each other to rotate the components toward the bracket 3. The components may be hinged to the bracket on an opposite side to which the drive shaft of the rotation motor 47 is connected to rotate the components.

[0044] Hereinafter, an operation of the spot welding device 1 having such a configuration will be described with reference to Fig. 5 to 8 described. Fig. 5 to 8 are operating state diagrams of the spot welding apparatus according to the exemplary embodiment of the present invention.

[0045] First, when welding is carried out, the third welding tip 33 of the lower welding gun 11 supports a lower portion of a welding spot (not shown) of a welding target in a state of Fig. 5. Thereafter, the second welding tip 25 presses the top of the welding point to perform the welding operation (for example, an X-type welding gun is used), while the upper welding gun 7 moves downward by operating the up-down moving unit 5, as shown in Fig. 6.

[0046] In addition, the upper welding gun 7 retracts in an arrow direction by operating the left and right movement unit 9 as shown in Fig. 7, when the first welding tip 23 of the upper welding gun 7 is required due to a change in the shape and position of the welding spot of the welding target. Thereafter, the upper welding gun 7 is moved downward so that the first welding tip 23 of the upper welding gun 7 corresponds to the fourth welding tip 35 of the lower welding gun 11 by operating the up-down movement unit 5, as shown in Fig. 8.

[0047] In addition, the fourth welding tip 35 of the lower welding gun 11 supports the bottom of the welding spot of the welding target again, and the upper welding gun 7 advances in an arrow direction, and as a result, the first welding tip 23 presses against the top of the welding spot, thereby performing the welding operation (for example, a C-type welding gun).

[0048] Meanwhile, the rotating motor 39 of the rotating unit 37 is operated to rotate the components except the clamp 3 when the shape and position of the welding spot of the welding target are changed, as shown in Fig. 4. As a result, the welding operation is carried out while the change in the shape and position of the welding spot of the welding target is easily managed through a series of operation states described above.

[0049] Advantageously, according to the spot welding apparatus 1 according to the exemplary embodiment of the present invention configured as above, the welding operation is carried out by automatically selecting the respective welding spatters 23, 25, 33, and 35 to correspond to the different welding points of the welding target by the first and second welding tips 23 and 25 provided in the upper welding gun 7 and the third and fourth welding tips 33 and 35 provided in the lower welding gun 11 and the rotating unit 45, so as to quickly carry out the welding operation in a limited space with a minimum amount of time.

[0050] Furthermore, the spot welding device can be universally applied to a variety of vehicle models regardless of the vehicle model, the position, and the shape of a welding spot, and a fast welding process is provided to improve the productivity, flexibility, and efficiency of a vehicle body process. In addition, the number of robots installed in a production line can be reduced by using one device, thus saving on building investment costs.

[0051] While the invention has been described in conjunction with what are presently considered to be practical exemplary embodiments, it should be understood that the invention is not limited to the disclosed embodiments, but on the contrary is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

[1] Spot welding device (1), comprising: An up-down movement unit (5) including a slide block provided on one side of an arm of a robot to move vertically by the operation of an actuator (29); an upper welding gun (7) mounted on the slide block, the upper welding gun (7) including a first welding tip (23) projecting in a longitudinal direction of a front end of the arm and a second welding tip (25) projecting in a downward direction to the longitudinal direction; a left-right movement unit (9) installed on one side of the upper welding gun (7) for horizontally moving the upper welding gun (7) by actuating the actuator (29); and a lower welding gun (11) supported to correspond to a lower side of the upper welding gun (7). [2] Spot welding device (1) according to claim 1, wherein: The up-down movement unit (5) is mounted on a separate clamp (3) which is mounted on the arm of the robot. [3] Spot welding device (1) according to claim 1, wherein: The lower welding gun (11) includes a third welding tip (33) provided vertically at the front end of the arm and corresponding to the second welding tip (25), and a fourth welding tip (35) projecting horizontally to the third welding tip (33) and in an opposite direction to the first welding tip (23). [4] Spot welding device (1) according to claim 2, wherein: The up-down movement unit (5) includes: A body (13) installed vertically on the bracket (3); a drive motor (21) installed at a lower end of the body (13); and a slider (17) provided to move vertically on a screw shaft installed in the body (13) and rotated by operation of the drive motor (21), and supported with the upper welding gun (7). [5] Spot welding device (1) according to claim 1, wherein: The left-right movement unit (9) includes: A gear (27) provided on one side of the upper welding gun (7); an actuator (29) installed on one side of the gearbox (27) parallel to the upper welding gun (7); and a movement block provided to move back and forth on a screw shaft installed on another side of the gear box (27) parallel to the actuator (29) and rotated by receiving the actuation of the actuator (29) by the gear box (27), and connected to the upper welding gun (7). [6] Spot welding device (1) according to claim 4, wherein: The drive motor (21) is a stepper motor whose revolutions per minute and direction of rotation are controllable. [7] Spot welding device (1) according to claim 1, wherein: A current conducting unit (37) which conducts current and is installed on either side of the upper welding gun (7) or the lower welding gun (11). [8] Spot welding device (1) according to claim 7, wherein: The power line unit (37) supplies power to the upper welding gun (7) via a bus bar and a shunt from a transformer (39) installed on a lower side of the lower welding gun (11). [9] Spot welding device (1) according to claim 1, wherein: The first and second welding tips (23; 25) of the upper welding gun (7) are spaced approximately 90° apart. [10] Spot welding device (1) according to claim 3, wherein: The third and fourth welding tips (33; 35) of the lower welding gun (11) are spaced approximately 90° apart. [11] Spot welding device (1) according to claim 1, wherein: A rotating unit (45) which rotates the upper welding gun (7) and the lower welding gun (11) to the clamp (3) is installed on one side of the clamp (3). [12] Spot welding device (1) according to claim 11, wherein: The rotating unit (45) is a rotating motor (47) which is installed on one side of the clamp (3). [13] Spot welding device (1) according to claim 12, wherein: The rotary motor (47) is a stepper motor whose revolutions per minute and direction of rotation are controllable.

Images