Spot welding device

Abstract

Spot welding device (1), comprising: a fixing panel (3) mounted on an arm (45) of a robot; a single upper welding gun (5) which is installed vertically on a front side of the fixing panel (3), and which is vertically reciprocated by a pressing unit (13), and moved horizontally to the fixing panel (3); a left-right movement unit (7) installed between the fixing panel (3) and the pressing unit (13) to move the upper welding gun (5) horizontally, the left-right movement unit (7) including: a rail (21) installed horizontally on the fixing panel (3); a sliding block (23) installed on the rail (21) and connected to the pressing unit (13); and a cylinder (33) provided on one side of the pressing unit (13) for moving the pressing unit (13) horizontally on the rail (21), wherein the upper welding gun (5) is moved linearly by the left-right moving unit (7) on the sliding block (23) connected to the rail (21); two or more lower welding guns (9; 29, 31) arranged horizontally to correspond to the upper welding gun (5); and an up-down movement unit (11) installed on the fixing panel (3) to move the lower welding gun (9) vertically back and forth.

Description

BACKGROUND(a) Field of the invention

[0001] The present invention relates to a spot welding apparatus, and more particularly to a spot welding apparatus that performs welding by selecting a lower welding gun that adjusts a welding spot of a welding target, to be universally applied to a plurality of car models, and 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 components, such as a press-formed body panel and the like, are joined together by a process such as welding to complete an integrated body. The finished body is painted, and rust protection is applied to the surface of the individual parts in a painting process. Afterward, a finishing process is performed, such as assembling a part of a power transmission system and parts such as damping, steering, and braking systems, and then assembling a door and trunk lid, a hood, and the like.

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

[0004] Resistance spot welding is a process in which contacting metal surfaces are joined by the heat generated by resistance to an electric current. As such, the weld is typically created by holding workpieces together under pressure exerted by the electrodes via a spot welding fixture attached to the front end of a spot welding robot's arm.

[0005] A welding gun used in a spot welding machine is divided into three types: an X-type welding gun, a C-type welding gun, and a special type welding gun which adopts a special lower arm according to the position of a welding portion and interference with the vehicle bodies.

[0006] 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 obtain the appropriate spot weld.

[0007] 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 welds, thereby reducing productivity and efficiency.

[0008] Furthermore, lower welding guns of various shapes must be adjusted according to the position and shape of the welding spot. As a result, building investment costs increase, and in particular, building and maintenance costs increase, and energy consumption is excessive when multiple robots are used, each supporting a spot welding fixture that applies a lower welding gun with a special shape. Furthermore, the space occupancy rate of the robot in a mass production line also increases.

[0009] For example, KR 10 2012 0 051 557 A describes a twin spot welder with variable pitch, capable of performing more welds in a limited space and time and of varying the pitch. KR 10 2003 0 005 837 A describes a welding gun with a double lower support, comprising a lower support and an auxiliary support that can rotate on a welding gun arm to weld with a welding gun regardless of the thickness of the part to be welded. Furthermore, JP 2013-188 783 A describes a two-shot spot welding device and a spot welding robot capable of welding two welding spots simultaneously.

[0010] The above information disclosed in this Background section is only to enhance the understanding of the background of the invention, and therefore may contain information which does not constitute prior art which is already known to a person of ordinary skill in the art in this country. Summary

[0011] The present invention was made in an effort to provide a spot welding apparatus that performs welding by incorporating a plurality of lower welding guns, and automatically selecting a lower welding gun from the plurality of welding guns according to different welding spots of a welding target, to be universally applied to various vehicle models, to quickly perform welding in a limited space with a minimum amount of time, to improve productivity, flexibility, and efficiency of a vehicle body process, and to reduce the number of robots by one device application to save installation costs.

[0012] According to the invention, the object is achieved by a spot welding device having the features of claim 1.

[0013] An exemplary embodiment of the present invention provides a spot welding apparatus including: a fixing panel supported on an arm of a robot; an upper welding gun vertically installed on a front side of the fixing panel and vertically reciprocable by a pressing unit and horizontally moved relative to the fixing panel; a left-right moving unit installed between the fixing panel and the pressing unit for horizontally moving the upper welding gun; two or more lower welding guns arranged horizontally to correspond to the upper welding gun; and an up-down moving unit installed on the fixing panel for vertically reciprocating the lower welding gun.

[0014] The pressing unit may include a gear box provided on top of the upper welding gun, a pressing actuator supported on a lower side of the gear box housing, and a moving block vertically installed on another lower side of the gear box housing and reciprocating on a screw shaft rotated by receiving an actuation of the pressing actuator through the gear box.

[0015] According to the invention, the left-right movement unit includes a rail horizontally installed on the fixing panel, a sliding block installed on the rail and connected to the pressing unit, and a cylinder provided on one side of the pressing unit for moving the pressing unit horizontally on the rail. The pressing actuator can be configured and controlled by a stepping motor whose rotational speed and rotation direction are controllable. The left-right movement unit, the rails, and the sliding blocks can be configured in a plurality on the fixing panel.

[0016] The up-down movement unit may include a cylinder connected to correspond to the lower welding guns on the fixing panel in the rear of the pressing unit, and an ascending and descending means installed between the lower welding guns and the fixing panel for guiding ascending and descending of the lower welding gun by operation of the cylinder.

[0017] The ascending and descending means may include a vertical rail installed on the fixing panel and a guide block connected to the vertical rail and connected to an arm of the lower welding gun.

[0018] The lower welding gun may include first and second lower welding guns having differently shaped welding tips.

[0019] The cylinder may include a first cylinder and a second cylinder corresponding to the first and second lower welding guns.

[0020] Furthermore, in some exemplary embodiments, a power line unit that supplies power to the upper welding gun and the lower welding gun may be installed on the fixing panel. The power line unit may include a transformer installed on the fixing panel and a bus bar connected to the transformer to supply power to the upper welding gun and the lower welding gun.

[0021] According to an exemplary embodiment of the present invention, a welding operation can be performed while automatically selecting a corresponding lower welding gun among the plurality of lower welding guns according to the different welding points of a welding target while an upper welding gun is moving horizontally to perform a rapid welding operation in a confined space in a minimum amount of time.

[0022] Advantageously, the spot welding device can be universally applied to various vehicle models regardless of a vehicle model and the positioning of the shape of a welding spot and enables a rapid welding process to improve the productivity, flexibility and efficiency of a vehicle body process, and to reduce the number of robots installed in an assembly line by using one device to secure the building investment cost. 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 a pressing unit of the spot welding apparatus according to an 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 up-down moving unit of the spot welding apparatus according to the exemplary embodiment of the present invention. Fig. 5 is a perspective view of a power line unit of the spot welding apparatus according to the exemplary embodiment of the present invention. Fig. 6 to 9 are operation diagrams of the spot welding apparatus according to the exemplary embodiment of the present invention. Detailed description of the embodiments

[0023] 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.

[0024] Unless expressly stated or clear from the context, the term "about" as used herein should be understood as being within a range of scientifically normal tolerances, 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%, 5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless the context clearly indicates otherwise, all numerical values stated herein are deemed to include the term "about."

[0025] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying figures. However, since the size and thickness of each component illustrated in the drawings are expressed freely, the present invention is not expressly limited to the size and thickness illustrated in the drawings, and the thickness is exaggerated to clearly express the various parts and portions.

[0026] Parts not associated with description have been omitted in order to clearly describe the exemplary embodiments of the present invention, and the names of the elements in the following description have been differentiated into first, second and the like in order to clearly distinguish the elements, since the names of the elements are the same and are not particularly limited in order thereof.

[0027] 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 still includes a plurality of lower welding guns, and performs a welding operation while the upper welding gun presses a welding spot by automatically selecting the lower welding gun to correspond to the different welding spots of a welding target.

[0028] As a result, the spot welding apparatus 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 in a minimum time to increase the productivity, flexibility and efficiency of a vehicle body process, and reduce the number of robots by using one apparatus to secure the installation cost.

[0029] 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 fixing panel 3, an upper welding gun 5, a left and right moving unit 7, a lower welding gun 9, and an up-down moving unit 11.

[0030] The fixing panel 3 has a support portion (not shown) supported on a robot arm (not shown) and formed on one side thereof to be supported on the robot arm. The upper welding gun 5 is vertically installed on a front side of the fixing panel 3 to reciprocate vertically by a pressing unit 13. The pressing unit 13 presses an upper surface of a welding spot of a welding target while the upper welding gun 5 moves vertically.

[0031] Fig. 2 is a perspective view of a pressing unit of a spot welding apparatus according to the exemplary embodiment of the present invention. Referring to Fig. 2, the pressing unit 13 includes a gear housing 15, a press actuator 17, and a movement block (not shown). The gear 15 is provided on an upper side of the upper welding gun 5 on the front side of the fixing panel 3.

[0032] The press actuator 17 can be installed parallel to the upper welding gun 5 on one side of the gearbox 15. In this case, the press actuator 17 can be formed by a stepper motor whose rotational speed and direction of rotation are controllable.

[0033] The moving block (not shown) is installed through a vertical housing 15, which is vertically installed on the other side of the gear box 15, and is provided to be vertically reciprocable on a screw shaft (not shown), which receives an actuation of the pressing actuator 17 through the gear box 15, and is rotated in the vertical housing 19.

[0034] Here, the upper welding gun 5 is mounted on the movement block, and the upper welding gun 5 is moved vertically by actuating the press actuator 17 during the welding process. Meanwhile, the press actuator 17 can be configured as a roller screw actuator that converts the torque of an electric motor into a linear motion.

[0035] The press actuator 17 rotates the screw shaft (not shown) which is positioned parallel to the press actuator 17 via the gear 15, and as a result, the movement of the moving block 31 is converted into the linear movement on the screw shaft to move the upper welding gun 5 vertically back and forth.

[0036] The roller screw actuator is based on a configuration in which a nut-like moving block engages a thread of a screw shaft and moves it forward and backward, while a screw shaft connected to a drive shaft of the electric motor is rotated by the motor drive force. Since a configuration of a roller screw actuator that can be used as an actuator is a well-known configuration widely used in the industry, a detailed description thereof will be omitted. In addition, the left-and-right movement unit 7 may be installed on the fixing panel 3 between the fixing panel 3 and the pressing unit 13 to guide the horizontal movement of the upper welding gun 5.

[0037] 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-right movement unit 7 includes a rail 21, a sliding block 23, and a cylinder 25.

[0038] The rail 21 is horizontally installed on the fixing panel 3 between the left and right moving unit 7 and the fixing panel 3. In addition, the sliding block 23 is movably connected on the rail 21, and is connected to the vertical housing 19 of the pressing unit 13.

[0039] In the exemplary embodiment of the present invention, the cylinder 25 is provided horizontally on one side of the vertical housing 19 of the press unit 12, connected by a cylindrical rod (not shown), and moves the press unit 13 horizontally on the rail 21 by actuating the cylindrical rod. In this case, the cylinder 25 may be formed by a pneumatic cylinder.

[0040] Therefore, since the left-and-right movement unit 7 moves the pressing unit 13 to one side, the upper welding gun 5 also moves horizontally on the rail 21. In addition, the left-and-right movement unit 7, the rails 2, and the slide plate 23 may be vertically formed in a plurality of them on the fixing panel 3. As a result, the left-and-right movement unit 7 can move the pressing unit 13 to one side while the left-and-right movement unit 7 is more stably connected and supported by the vertical casing 19 of the pressing unit 13.

[0041] Meanwhile, one or more lower welding guns 9 are horizontally spaced from each other at the bottom of the fixing panel 3 to correspond to the upper welding gun 5. In this case, the lower welding gun 9 may include a first lower welding gun 29 and a second lower welding gun 31 having different shapes of welding tips 27. In addition, the up-down movement unit 11 is installed on the fixing panel 3 to vertically reciprocate the lower welding gun 9.

[0042] Fig. 4 is a perspective view of an upper and lower moving unit of the spot welding apparatus according to the exemplary embodiment of the present invention. Referring to Fig. 4, the up-down movement unit 11 includes a cylinder 33 and ascending and descending means 35. The cylinder 33 is installed on the top of the fixing panel 3 in the rear of the pressing unit 13 to be connected to the lower welding gun 9, respectively.

[0043] In this case, the cylinder 33 may be formed of a pneumatic cylinder, and may include a first cylinder 37 and a second cylinder 39, which correspond to the first lower welding gun 29 and the second lower welding gun 31, respectively.

[0044] Therefore, the first and second cylinders 37 and 39 are connected to the first and second lower welding guns 29 and 31 through an actuator rod to independently move the first and second lower welding guns 29 and 31 vertically.

[0045] The ascending and descending means 35 are installed on the fixing panel 3 between the lower welding gun 9 and the fixing panel 3 to guide ascending and descending of the lower welding gun 9 according to the operation of the cylinder 25.

[0046] In this case, the ascending and descending means 35 may be installed in a plurality to respectively guide each of the first lower welding guns 29 and the second lower welding gun 31.

[0047] In addition, a detailed configuration is omitted since the ascending and descending means 35 are a known configuration used in industries in which a guide block 43 is moved on a vertical rail 41.

[0048] The vertical rail 41 may be provided vertically between the lower welding gun 9 and the fixing panel 3. In addition, the guide block 43 is movably mounted on the vertical rail 41 to be connected to an arm 45 of the lower welding gun 9. Therefore, when the lower welding gun 9 ascends and descends with the operation of the up-down moving unit 11, the lower welding gun 9 ascends and descends vertically while the arm 45 is guided along the vertical rail 41.

[0049] Meanwhile, a power line unit 47 which supplies power to the upper welding gun 5 and the lower welding gun 9 may be installed on the fixing panel 3.

[0050] Fig. 5 is a perspective view of a power line unit of the spot welding apparatus according to the exemplary embodiment of the present invention. Referring to Fig. 5, the power line unit 47 includes a transformer 49 and a bus bar 51. The transformer 49 is installed on the fixing panel 3, and the bus bar 51 is connected to the transformer 49 to supply power to the upper welding gun 5 and the lower welding gun 9. The power line unit 47 installed in the spot welding device 1 has a well-known function widely used in the art, and a more detailed description thereof will be omitted.

[0051] Hereinafter, the operation of the spot welding device 1 having such a configuration will be described with reference to Fig. 6 and Fig. 7 described.

[0052] Fig. 6 to 7 are operational diagrams of the spot welding apparatus according to the exemplary embodiment of the present invention. First, with reference to Fig. 6, a state is shown in the figure, which is a state before the spot welding device 1 performs a welding operation, and when the welding operation is performed, the spot welding device 1 moves to a welding point of a welding target by the operation of a robot.

[0053] Thereafter, when the welding operation is carried out, the first lower welding gun 29 supports the bottom of the welding spot, while the first lower welding gun 29 descends by operating the first cylinder 37 of the up-down movement unit 11, as shown in Fig. 7 shown.

[0054] In addition, the upper welding gun 5 performs a welding operation by pressing the top of the welding spot, while the upper welding gun 5 descends by actuating the pressing unit 13.

[0055] Meanwhile, when the second lower welding gun 31 is required due to a change in the shape and position of the welding spot of the welding target, the cylinder 25 of the left and right moving unit 7 is operated to move the pressing unit 13 connected to the upper welding gun 5 to the upper side of the second lower welding gun 31 as shown in Fig. 8, moves to move.

[0056] Thereafter, when the welding operation has been carried out, the lower welding gun 25 is returned to an original state, and the second lower welding gun 31 supports the bottom of the welding point, while the second lower welding gun 31 descends by an operation of the second cylinder 39 of the upper and lower moving unit 11, as shown in Fig. 9.

[0057] In addition, the upper welding gun 5 performs the welding operation by pressing the top of the welding point, while the upper welding gun 5 descends by actuating the pressing unit 13.

[0058] Advantageously, the spot welding apparatus 1 according to the exemplary embodiment of the present invention performs the welding operation by changing the position of the upper welding gun 5 toward the corresponding first or second lower welding gun 29 or 31 between the first and lower welding guns 29 and 31 according to the position and shape of the welding spot, so as to flexibly cover the shapes and positions of various welding spots.

[0059] Further, 1, the welding operation is carried out by automatically selecting the first or second lower welding gun 29 or 31 according to the different welding points of the welding target to quickly carry out welding in a limited space with a minimum amount and time.

[0060] In addition, the spot welding device can be universally applied to various vehicle models regardless of the vehicle model, and the position and shape of a welding spot, and enables a rapid welding process to improve the productivity, flexibility and efficiency of a vehicle body process, and reduce the number of robots installed in a production line by applying a device to reduce building investment costs.

[0061] While this invention has been described in connection 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. List of reference symbols 1 spot welding device 3 Fixing panel 5 upper welding gun 7 Left and right movement unit 9 lower welding gun 11 Up-down movement unit 13 Press unit 15 Gearbox housing 17 Pressactor 19 vertical housing 21 Rail 23 Sliding block 25 cylinders 27 Welding tip 29 first lower welding gun 31 second lower welding gun 33 cylinders 35 ascent and descent means 37 first cylinder 39 second cylinder 41 vertical rail 43 Guide block 45 Arm 47 Power line unit 49 Transformer 51 Busbar

Claims

[1] Spot welding device (1), comprising: a fixing panel (3) mounted on an arm (45) of a robot; a single upper welding gun (5) which is installed vertically on a front side of the fixing panel (3), and which is vertically reciprocated by a pressing unit (13), and moved horizontally to the fixing panel (3); a left-right movement unit (7) installed between the fixing panel (3) and the pressing unit (13) to move the upper welding gun (5) horizontally, the left-right movement unit (7) including: a rail (21) installed horizontally on the fixing panel (3); a sliding block (23) installed on the rail (21) and connected to the pressing unit (13); and a cylinder (33) provided on one side of the pressing unit (13) for moving the pressing unit (13) horizontally on the rail (21), wherein the upper welding gun (5) is moved linearly by the left-right moving unit (7) on the sliding block (23) connected to the rail (21); two or more lower welding guns (9; 29, 31) arranged horizontally to correspond to the upper welding gun (5); and an up-down movement unit (11) installed on the fixing panel (3) to move the lower welding gun (9) vertically back and forth. [2] Spot welding device (1) according to claim 1, wherein: the pressing unit (13) includes: a gear provided on a top side of the upper welding gun (5); a press actuator (17) which is mounted on a lower side of the gear; and a movement block which is installed vertically on another lower side of the gear box and moves back and forth on a screw shaft which is rotated by receiving an actuation of the press actuator (17) by the gear box. [3] Spot welding device (1) according to claim 1, wherein: the press actuator (17) is formed by a stepper motor whose speed per minute and direction of rotation are controllable. [4] Spot welding device (1) according to claim 1, wherein: in the left-right movement unit (7) the rails (2) and the sliding plate (23) are formed in a plurality on the fixing panel (3). [5] Spot welding device (1) according to claim 1, wherein: the up-down movement unit (11) includes: a cylinder (33) connected to correspond to the lower welding gun (9) on the fixing panel (3) in the rear of the pressing unit (13); and ascending and descending means (35) installed between the lower welding gun (9) and the fixing panel (3) for guiding ascending and descending of the lower welding gun by the operation of the cylinder (33). [6] Spot welding device (1) according to claim 5, wherein: the ascent and descent means (35) include: a vertical rail (41) installed on the fixing panel (3); and a guide block (43) coupled to the vertical rail (41) and connected to an arm (45) of the lower welding gun (9). [7] Spot welding device (1) according to claim 1, wherein: the lower welding gun includes first and second lower welding guns (29, 31) which have differently shaped welding tips (27). [8] Spot welding device (1) according to claim 7, wherein: the cylinder (33) includes a first cylinder (37) and a second cylinder (39) corresponding to the first and second lower welding guns (29, 31). [9] Spot welding device (1) according to claim 1, wherein: a power line unit (47) which supplies power to the upper welding gun (5) and the lower welding gun (9) is installed on the fixing panel (3). [10] Spot welding device (1) according to claim 9, wherein: the power line unit (47) includes: a transformer (49) installed on the fixing panel (3); and a bus bar (51) connected to the transformer (49) to supply current to the upper welding gun (5) and to the lower welding gun (9).

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