JP2007260771A - Automatic spot welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of automatically welding a welding spot by placing a workpiece on a planar table electrode that serves as a lower electrode over the entire surface and by moving a welding gun of an upper electrode three-dimensionally without requiring human work. <P>SOLUTION: In the spot welding method, the workpiece W is placed on a planar electrode, namely, the table electrode 110 serving as the lower electrode at any place on the surface. and while the welding gun 130 is caused to serve as an upper electrode at each welding spot of the workpiece W by a command from an electronic control mechanism 200 such as a computer on the basis of a prescribed program, a portal frame 120 is interposed that straddles over the table electrode 110 in the width direction, the welding gun is three-dimensionally moved, elevated/lowered, and pressurized, so that spot welding is successively performed at the welding spots. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an automatic spot welding method. More specifically, a plate-like table electrode is used as a lower electrode, and any part of the entire surface works as a lower electrode, whereas anywhere on the table electrode. In addition, welding is performed by moving a rod-shaped welding gun, and the movement and welding mode of this welding gun is processed by an electronic control mechanism such as a computer according to the welding conditions including the material and thickness of the material to be welded. This is a spot welding method in which welding points such as a workpiece are sequentially welded under control according to a programmed program, and in particular, a series of welding points of a workpiece to be welded with a table electrode is made almost manually. The present invention relates to an automatic spot welding method capable of welding without depending on the above.

  In this specification, automatic welding or robotization of welding work is referred to as the fact that there is almost no human intervention in the work set and welding work, and that some parts can be welded without human intervention. Is also included. In addition to metal plates and other plate-like materials and mold materials, materials to be welded include materials generally called structures such as boxes, containers, and frames.

  For example, when joining materials to be welded such as rolled steel plates, aluminum and their alloy materials, and Zn-plated steel plates, at least two or more materials to be welded are stacked and sandwiched from above and below with a pair of electrodes. Spot welding is used in which welding is performed under pressure and energization. This welding method is called an electric welding method because electric energy is used as a welding heat source. It is a pressure welding and fusion welding, and is the most popular welding method. In addition to the automobile industry, it is also used in the fields of metal processing and sheet metal processing. It's being used.

  A spot welder takes only a few seconds to form one nugget, and this nugget is formed without being attacked by oxygen in the air (oxidation) between the welded materials overlaid. There is an advantage that a shielding gas such as an active gas or an additive is not required. In addition to this advantage, there is an advantage that welding can be performed using a robot or the like once the welding conditions such as the welding current and the applied pressure are set according to the material to be welded. Many robotization and automation technologies for stable welding work have been developed for the purpose of improving these areas, and most of the proposed technologies are robotization technologies. It is no exaggeration to say that there is.

  Depending on the application, spot welders can be divided into large-scale dedicated bodies for mass production such as large automobile bodies and small-sized ones for sheet metal processing of various types of small rods. It is said to be a stationary type in which the upper and lower electrodes are fixed.

  In other words, the former is a series of technical improvements that accompany the development of the automobile industry. Specifically, in addition to its use as a dedicated machine in fields such as the manufacture of automobile bodies with a great number of model changes, unmanned welding. It was developed for the purpose of making it into a robot. In short, rather than the welding technique itself, a so-called welding robot itself is proposed. On the other hand, spot welding machines used for machining of the latter small-rod multi-type workpieces represented by stationary spot welding machines have been improved for several decades. In short, there are few technical improvements such as automation and robotization.

  In short, the principle of spot welding is the same for large-sized automobile body welding machines and batch-type stationary welding machines. Each of them is a stationary spot welder, which is a type in which two workpieces and the like are overlapped and sandwiched between a pair of upper and lower rod-like electrodes to which they are fixed and pressurized and energized. That is, a pair of welding electrodes for sandwiching two materials to be welded and applying welding pressure and welding current are composed of rod-shaped materials such as copper, and the current to be applied is reduced and the welding pressure is increased to pressurize the weld locally. Melt and weld. The nugget that is formed is a so-called nugget of an arcuate welded portion because a large current is passed in a short period of time and pressurized with a high pressure. Therefore, both the upper and lower electrodes need to be rod-shaped, and in particular, there are almost no attempts to improve the structure itself, which increases the applied pressure and the amount of current by narrowing the tip and narrowing the current-carrying area to the material to be welded. Not done.

  For this reason, since a means for forming a welded portion called a spot is considered in this way, it is a large spot welder incorporated as a part of a production line such as an automobile body, and the welded portion forming means is improved. The development in the field of jigs required for the transportation of parts to be welded and welding, etc., is the result of the robotization and automation of welding work. On the other hand, stationary spot welders used for so-called sheet metal processing are batch-type, and robotized and automated ones have hardly been proposed, and the required jig There is no development or improvement at all.

  In so-called sheet metal processing, containers such as metal frames and metal boxes are often formed by cutting and joining metal plates, and there are often welding points to be welded inside. Although such a welding point cannot be directly hit from the outside by a rod-shaped welding gun, this drawback is also solved because the welding gun 3 can be inserted from the side.

  In short, it is not an exaggeration to say that when there is a welding spot inside a structure having a complicated shape, welding cannot be performed by a stationary welding machine that welds the welding spot between the upper and lower electrodes. When welding is inevitably carried out, the operator himself / herself holds the welding material itself in a position where a rod-like welding gun can enter and welds in that posture. This work is very hard work. A large number of workers are required, which is not preferable. In addition, the welding tips at the top and bottom of the upper and lower electrodes are narrowed down. When pressure is applied to such welding tips, welding flaws and after-welding will inevitably remain at the welding point, making this removal work extremely complicated. It is a heavy heavy labor, which increases welding costs.

  From this point, the present inventors first configured one of the pair of electrodes sandwiching the material to be welded from above and below as a plate-like table electrode, and any of the surfaces of this electrode. However, we proposed a welding machine that can also work as an electrode. This welding machine has a small rod and a complicated shape structure, especially a structure with a welding spot to be welded inside, depending on the position of the welding spot, It is a spot welder that can be selected and can also achieve work such as processing and assembly accompanying welding. (Refer to the specification of Japanese Patent No. 3445636)

  This spot welder 1 is as shown in FIG. 6 and uses a table electrode or a sheet-like electrode made of a flat conductive plate-like material as the lower electrode 2 and a rod-like electrode as the upper electrode. This is a welding machine that operates the welding gun 3. The table electrode 2 can act as a lower electrode anywhere on the surface, and has an advantage that a workpiece W such as a metal material can be processed and assembled thereon. This spot welding machine 1 lowers the bar-shaped welding gun 3 in a vertical posture toward the workpiece W placed on the table electrode 2 to bring the workpiece W into a bar-like shape with the table electrode 2. Scissors are welded between the welding gun 3. In this apparatus, the entire surface of the plate-like table electrode 2 is used as a lower electrode. Therefore, the welding gun 3 is supported by a telescopic support beam 4 and a support arm 5, and the table. It is necessary to configure the welding gun 3 so that it can freely translate over the entire surface of the electrode 2. In short, the welding gun 3 is moved by the expansion and contraction of the support arm 5, and when the welding hit point is reached, the welding gun 3 is lowered to enable welding.

  In the spot welder 1, the surface of the table electrode 2 can be used as a work surface in addition to working as a lower electrode. For this reason, even if there are a large number of welding points on one welded material, the welding gun 3 can be moved and welded by the expansion and contraction operation of the support arm 5 without moving the welded material. A cooling water passage can be provided over the entire surface of the table electrode, and the cooling capacity is extremely high. Since the applied pressure during welding can be dispersed and supported locally on the surface of the table electrode 2, no trace of welding remains. Furthermore, since the welding gun 3 forms one part of the lever mechanism in the lateral orientation, the welding force is increased and the pressure is increased, so that a weld joint having high strength can be obtained.

On the other hand, with the development of welding machines that use such table electrodes, this spot welding machine is not limited to the sheet metal industry, which was said to be a small rod, but also a large switchboard, housing for electronic devices and home appliances, etc. Thus, it is also used in the manufacture of what requires internal welding. However, the previously proposed welding machine is configured such that the welding gun 3 acting as the upper electrode is combined with the pivotable support arm 5 to expand and contract by rotating each support arm 5. However, this mechanism becomes larger, and accordingly, a welding gun for a cooling mechanism and a current-carrying mechanism is attached, and these are supported by a pivotable combination of support arms 5 and 5, so that each support arm is supported. -It is very difficult to continue or automate the movements of the mud according to a certain rule. From this point of view, it is desired to improve the support mechanism of the welding gun and thereby to automate or robotize the three-dimensional movement of the welding gun 3 on the plate-like table electrode 2. Nevertheless, this request was not satisfied.
Japanese Patent No. 3445636

  The object of the present invention is to solve the above-mentioned drawbacks, and in the same way as the previously proposed spot welder, the surface of the table electrode is used as a lower electrode and also used as a work surface. A welding gun that works as an upper electrode is supported via a portal frame, and the displacement of the welding gun relative to the portal frame is used as part of the position information to position the welding gun, automate welding operations, etc., robot We propose a spot welding method that can achieve this.

  That is, according to the method of the present invention, on a fixed table electrode serving as a lower electrode, a welding gun serving as an upper electrode is designated by a command from an electronic control mechanism according to a predetermined program corresponding to the position of a welding spot to be welded and welding conditions. In a spot welding method in which welding points are spot welded sequentially by moving, raising and lowering, and pressurizing in a three-dimensional direction, a portal frame with a welding gun mounted so as to be movable up and down is straddled across the width direction of the table electrode. While detecting the movement displacement that moves the portal frame in the vertical direction on the table electrode according to the program, this is input to the electronic control mechanism as the vertical movement displacement on the table electrode of the welding gun, The movement displacement of the welding gun moving along the portal frame is detected, and this is input to the electronic control mechanism as the movement displacement in the lateral direction on the table electrode of the welding gun, and the welding gun is moved. The gun is positioned on the table electrode, facing the positioned welding spot, the welding gun is lowered from the portal frame by a command from the electronic control mechanism, and the load current during pressurization reaches the set value. It is sometimes characterized in that the welding of one welding spot is completed.

  As described above, according to the method of the present invention, one electrode is composed of a plate-like table electrode that acts as a lower electrode everywhere on the surface, and a welding gun that acts as an upper electrode can freely move thereon. . Spot welding can be performed freely with the workpiece to be welded. Further, the welding gun moves or descends through the gate frame, and this movement and lowering can be automatically achieved through an electronic control mechanism such as a computer. The electronic control mechanism moves, descends and pressurizes the welding gun according to a command from a program that incorporates welding conditions such as the material and dimensions of the workpiece, and robotization can be achieved even in spot welding in the sheet metal processing field.

  A preferred embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a flowchart of one preferred embodiment of the method of the present invention.

  FIG. 2 is an explanatory diagram of an example for carrying out the method of the present invention shown in FIG.

  FIG. 3 is an explanatory diagram for welding a welding spot existing in one structure by the method of the present invention.

  FIG. 4 is an end view of the automatic welding machine shown in FIG. 1 as viewed from one end face of the welding machine for carrying out the method.

  FIG. 5 is a plan view of the welding machine shown in FIG.

  FIG. 6 is an explanatory view of a spot welder according to a conventional example previously proposed by the applicant.

  First, FIG. 1 is a flow sheet showing one embodiment of the method of the present invention as described above, and reference numeral 100 generally indicates a spot welder used when welding by this method. ing. The specific structure of the spot welder indicated by reference numeral 100 is as shown in FIGS. The spot welder 100 is connected to an electronic control mechanism 200 such as a computer. The electronic control mechanism 200 is connected to a material to be welded, plate thickness, pressure, and other input data via an operation box 250 described later. The electronic control mechanism 200 is operated according to a program based on the input data, and a command is sent to the welding gun 130, so that the welding gun 130 moves in a three-dimensional direction via the portal form frame 120 described later. Alternatively, the welding is automatically performed with almost no manual operation by simply moving up and down and further turning and inputting input data such as material and plate thickness from the operation box 250.

  That is, as shown in FIG. 1, the electronic control mechanism 200 is connected to an input unit such as an operation box 250, a manual operation box 260, and an input computer 251, and these inlets are previously welded to be welded. Data such as the material, shape, and structure of the material is input, and a program is created and stored based on the data. When starting welding, a program selected from these programs according to welding conditions such as the material and thickness of the material to be welded, or a program obtained as a result of arithmetic processing in the electronic control mechanism 200 is selected. The activation motors 211, 212, 220, 230, and 240 of the welding gun 130 and the portal frame 120 on which the welding gun 130 is mounted in the welding machine 100 are rotationally activated. As a result, the welding gun 130 moves, moves up and down, and pressurizes as previously determined, and the welding points of the workpiece W are sequentially welded sequentially without depending on the hand.

  As shown in FIGS. 4 and 5, the spot welder 100 used for such automatic spot welding includes a table electrode 110 serving as a lower electrode and a welding gun 130 serving as an upper electrode. The table electrode 110 is made of a flat conductive plate (preferably, a copper plate or an alloy plate thereof), and the structure of such a table electrode 110 was previously proposed by the present inventor as shown in FIG. Is equivalent to The table electrode 110 is connected to one pole of a power source E (see FIG. 5) through a controller 180, and the entire surface serves as a lower electrode. On the other hand, the portal frame 120 is moved on the table electrode 110 without moving the welding gun 130 in the three-dimensional direction on the table electrode 110, whereas the portal frame 120 is moved. The welding gun 130 is configured to be movable in a three-dimensional direction via the portal form frame 120. That is, the portal frame 120 is provided on the table electrode 110 so as to be bridged across the width direction. The welding gun 130 is mounted on the portal frame 120, and the welding gun 130 is positioned by controlling the movement or displacement of the portal frame 120 by a command based on the program in the electronic control mechanism 200, and the welding spot is determined. Welds automatically in sequence. An example is a portal form 120 shown in FIG. The angle material can be configured in the form of a portal, but if configured in this way, the welding gun 130 and its lifting motor can be stably held, especially when two portal frames are arranged in parallel and run as a unit. It can also be configured as possible. As will be described later, the portal frame 120 can be constructed in any manner as long as it can be moved in the vertical direction on the table electrode 110.

  On the table electrode 110 serving as the lower electrode, the welding gun 130 serving as the upper electrode is moved in the three directions of the table electrode 110 in the vertical, horizontal and height directions, that is, in the three-dimensional direction. It moves to a desired welding point according to the converted movement path and is positioned. After the positioning, the welding gun 130 is lowered so that the workpiece W is sandwiched between the table electrode 110 and the welding gun 130, and is pressurized and energized for spot welding. If only the purpose of such a three-dimensional movement is achieved, it is possible to turn freely like the welding gun 130 in FIG. 6 like the previously proposed welding machine without necessarily interposing the portal frame 120. The object can also be achieved by holding the welding gun 130 at the tip of the connected support arm 5 and moving the welding gun 130 by turning the support arm 5. Alternatively, the object can be achieved even if the frame supporting the welding gun is constructed so as to be moved by being pulled on the table electrode 110. However, with this configuration, it is also difficult to accurately position the welding guns, that is, the equipment attached to the welding gun, that is, the water-cooled cable having a large diameter and a high weight. As a means for solving such a drawback, in the method of the present invention, the gate frame 120 is interposed, and the interposed gate frame 120 is controlled and held by the electronic control mechanism 200 so as to be always orthogonal to the longitudinal movement direction. The welding gun 130 is positioned on the table electrode 110 by vertically moving and controlling the movement of the welding gun 130 based on the movement of the portal frame 120.

  A welding gun 130 serving as an upper electrode is mounted on the portal frame 120, and the portal frame 120 is moved in parallel with the welding gun 130 over the width direction of the table electrode 110. That is, the vertical movement displacement on the table electrode 110 of the portal frame 120 is detected and confirmed, and this is given to the electronic control mechanism 200 as the vertical movement displacement on the table electrode 110 of the welding gun 130. In this way, the movement of the gate form 120 is controlled.

  For example, assuming that the vertical direction of the surface on the table electrode 110 is the X-axis direction, the displacement of the portal frame 120 on which the welding gun 130 is mounted as a moved value in the X-axis direction that is moved directly in the X-axis direction. Enter. In order to handle in this way, it is necessary that the gate frame 120 is always parallel and moved by the same degree. Also in this respect, if the intervening frame is a gate type having two legs, the two legs are individually driven by, for example, a servomotor, and their driving force, that is, the servomotor. The electronic control mechanism 200 controls the rotation angle between the control units under a predetermined control program. For this reason, it is possible to move and displace the portal form frame 120 in parallel and at the same level without any trouble.

  Since the welded gun 130 can move laterally in the X-axis direction in parallel with the mounted portal frame 120, the welding gun 130 that moves along the portal frame 120 moves in the width direction of the table electrode 110, that is, in the X-axis. It moves in the orthogonal Y-axis direction. A movement displacement in the Y-axis direction in which the welding gun 130 moves along the portal frame 120 is detected, and this can be regarded as a movement displacement in the lateral direction or the width direction on the table electrode of the welding gun. This can be input to the electronic control mechanism 200, and the welding gun 130 can be positioned based on the set value by the program selected in the electronic control mechanism 200. Welding of the positioned welding point is started by a command from the electronic control mechanism 200, is started by lowering the welding gun 130 in the welding machine 100, and when the welding is completed, a completion signal is sent from the welding machine 100 to the electronic control mechanism 200. Be emitted. Based on this, the welding gun 130 moves up and moves to the next welding spot, and the welding is repeated.

  In this case, for the completion of welding for each welding spot, a reference value corresponding to the current value based on the load when descending is set for each welding condition according to the material, shape, etc. of the material to be welded. If the change of the current value is input to the electronic control mechanism 200, welding of one welding point is completed by a command from the electronic control mechanism 200 when the value reaches a preset reference value.

  As described above, according to the method of the present invention, the welding gun 130 is moved three-dimensionally through the gate form frame 120 by the program selected according to the material of the material to be welded on the table electrode 110, and the welding spot is sequentially set. Weld to. The gate form frame 120 interposed in the movement of the welding gun 130 can be configured as shown in FIGS.

  First, the vertical movement of the portal frame 120 and the movement in the X-axis direction are performed by the vertical movement device 160. The welding gun 130 is moved in the Y-axis direction by the lateral traveling device 170 on the portal frame 120. The welding gun 130 mounted on the portal frame 120 moves up and down in the vertical direction, that is, in the Z-axis direction from the lifting and pressing device 150. In addition, the welding gun 130 is swung on the portal frame 120 by the swivel device 140.

  In short, as shown in FIG. 1, the welding gun 130 has a two-dimensional X-axis direction (the length direction of the table electrode 110) and a Y-axis on the table electrode 110 according to a command from the electronic control mechanism 200. In the direction (the width direction of the table electrode 110), ascends and descends along the Z-axis (the direction perpendicular to the table electrode 110), and further turns around the Z-axis (the rotation of the welding gun 130). Turn in direction C).

  As described above, on the table electrode 110 serving as the lower electrode, the welding gun 130 is moved in the X, Y, and Z axis directions via the portal frame 120 by the storage, processing, and designation of the electronic control mechanism 200, and the Z axis In the welding machine 100, these displacements such as movement and rotation are servo motors 211 (X1 axis movement), 212 (X2 axis movement), 220 (Y axis). ), 230 (Z-axis movement), 240 (rotation about the Z-axis). In FIG. 1, since the movement of the portal frame in the X direction is performed by both legs 121 and 121 of the portal frame 120, as is apparent from the above, this is shown in two parts.

  In FIG. 1, reference numerals 211, 212, 220, 230, and 240 denote a vertical movement device 160 (X-axis direction), a horizontal movement device 170 (Y-axis direction), and a lifting / lowering pressure device 150 (Z), respectively. Axial direction) is provided as a part of the welding machine 100 corresponding to each servo motor that rotationally drives the turning device 140 (rotation about the Z axis). The servo motors rotate by the number of rotations according to the program based on the processing result of the arithmetic processing unit in the electronic control mechanism 200. Note that these servo motors tend to have insufficient rotational force, and it is preferable to increase the rotational force by performing amplification or the like.

  In addition, when creating a program in the electronic control mechanism 200, the operation box 250, the manual operation box 260, and one of the input means are used as input means in order to input the welding conditions other than the material, pressure, thickness, and the like. A personal computer 251 is connected. In particular, when the personal computer 251 is connected as an input means, for example, three-dimensional CAD data can be read as it is into the electronic control mechanism 200, and each welding is sequentially performed based on the program thereby. The spot can be welded sequentially.

  Further, as shown in FIG. 3, there is a material W to be welded, for example, a container such as a frame or a box. Even if such a workpiece W remains in the vertical orientation and the rod-like welding gun 130 is lowered, the tip at the tip hits the overhanging portion W1 and cannot be welded. Even in such a material to be welded W, as shown in FIG. 3, a welding tip having a concave portion 133 (a U-shaped concave portion, a part of which is not shown) as the welding gun 130. It is possible to weld by using the one having 131 at the tip. That is, with such a welding gun 130, the overhanging portion W1 of the material W to be welded can be absorbed at the U-shaped recess 133, and as shown in FIG. 3, when this portion is penetrated, it is covered by the overhanging portion W1. Welding spot can be welded in the vertical orientation. When such a welding gun 130 is used, the tip of the welding tip 131 needs to coincide with the axis of the welding gun 130. When pressurizing under such conditions, there is no problem even if the applied pressure is increased. .

  As described above, according to the method of the present invention, welding can be automatically performed almost manually by inputting data from the input unit, but an example thereof is as shown in FIG.

  First, the workpiece W shown in FIG. 2 shows a part of the cross-sectional structure in FIG. The welded material W is a frame structure, and the welded material W has a central open portion W2 open, and the central open portion W2 is surrounded by a projecting portion W1 obtained by bending a previously-applied steel plate or the like. It is removed by the part W1. When welding a three-dimensional structure of this structure, that is, a box or a formwork, it is placed on the table electrode 110, and the welding tip 131 at the tip of the welding gun 130 is projected in advance at the recess 133 as shown in FIG. The part W1 is invaded and sequentially moved while being in contact with the position of the welding spot below it. Such position information of each welding spot is input to the electronic control mechanism 200, and is programmed and stored together with the movement locus of the welding tip 131. That is, the welding gun 130 is sequentially moved for each welding hit point, and is rotated when reaching the corner portion, and the position information of each welding hit point (displacement of the X-axis and Y-axis, and further about the Z-axis). A program for the movement trajectory of the welding gun, such as a rotation angle, is input to the electronic control mechanism 200 via the operation box 250.

  Subsequently, a program is stored based on the input data, and the welding gun 130 is sequentially moved by this, and welding is sequentially performed at welding points. When the corner portion is reached, the welding gun 130 is rotated in accordance with the program to change the direction, and the welding spot train is sequentially welded.

  In the program based on such information, the shape and structure of the workpiece W are greatly changed and complicated. Although the welding spot can be traced according to the shape by manual operation in advance, a container such as a box with a fixed shape can be inputted as it is with the three-dimensional CAD data read by the computer 251. In this way, further robotization of the welding operation can be achieved.

  That is, in order to achieve a plurality of welding continuously, although not shown, the workpiece W is applied to the reference scale in both the X-axis and Y-axis directions provided on the table electrode 110. Align. The welding gun 130 can be continuously moved based on the movement trajectory of the aligned program to achieve welding of a plurality of workpieces.

  Furthermore, when simultaneously welding workpieces having different shapes or the like, a program is created in advance for each workpiece, and these are collected to obtain positional information on the table electrode 110, and these are all collected. As a result, the welding gun 130 can be sequentially moved and welded.

  In addition, as shown in FIG. 4, the raising / lowering pressurization apparatus 150 which achieves raising / lowering with the pressurization to the to-be-welded material W by the welding gun 130 is integrated with the turning apparatus 140, as shown in FIG. The welding gun 130 can be configured to be moved up and down by the rotation of the lifting motor 151 via the ball nut mechanism 152 to the lifting motor 151. Further, instead of the lifting / lowering motor 151, it can be constituted directly by an air cylinder (not shown). However, as described above, the lifting / lowering motor 151 lifts and lowers the load during pressurization. It can be detected as a change in the current amount of the motor 151, and automation of welding can be easily achieved.

  In addition, a servo motor 240 is provided in the turning device 140 so that the welding gun 130 can turn around the center axis.

  The table electrode 110 is a plate-like material made of a conductive material of flat copper or an alloy thereof. This is connected to one pole of the welding power source 170 and serves as the lower electrode. The table electrode 110 has a plate-like sheet shape, which is also called a sheet electrode, and is characterized in that the entire surface functions as an electrode. Therefore, in addition to the X, Y, and Z axes, the welding gun 130 itself can be freely swung, and automation and robotization that are impossible with a stationary spot welder can be achieved.

  That is, for joining metal containers by sheet metal processing or the like, the welding points are welded by pressing a bar-shaped welding gun downward. In order to mechanize the spot welding machine, the spot welding machine previously proposed has proposed that a rod-shaped welding gun is incorporated in a telescopic support arm. However, in this support arm, it is complicated to mechanically and structurally expand or contract the expansion and contraction, and the improvement is required.

  From this point of view, the method of the present invention is based on the premise that the table electrode 110 is a plate-like sheet electrode and works as a lower electrode, and a gate frame 120 is interposed in the table electrode 110. The portal frame 120 is moved in the length direction of the table electrode 110 by the vertical movement device 160. A welding gun 130 serving as an upper electrode is attached to the portal frame 120 moving in the length direction with the material W to be welded between the table electrode 110.

  In short, it is possible to achieve the programming of the three-dimensional movement of the welding gun 130 by using the portal frame 120 by using it.

  As described above, it can be widely used in a field generally called sheet metal processing, and in particular, it can be used in the field of spot welding for joining in the manufacturing process of a structure having a complicated structure and shape.

It is a flow sheet of one preferred embodiment of the method of the present invention. It is one explanatory drawing of the example which implements the method of this invention shown in FIG. It is explanatory drawing at the time of welding the welding spot which exists in the inside of one structure by the method of this invention. It is the end view which looked at the automatic welder shown in FIG. 1 from one end surface of the welding machine which enforces a method. It is a top view of the welding machine shown in FIG. It is explanatory drawing of the spot welding machine which concerns on the prior art example which the applicant proposed previously.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Spot welder 110 Table electrode 120 Portal frame 130 Welding gun 180 Controller 200 Electronic control mechanism E Power supply

Claims (5)

On the fixed table electrode serving as the lower electrode, the welding gun serving as the upper electrode is moved in a three-dimensional direction by a command from the electronic control mechanism according to a predetermined program corresponding to the position of the welding spot to be welded and the welding conditions. In the spot welding method, where the welding spot is sequentially spot welded by raising and lowering and pressurizing,
A displacement of the gate frame, on which the welding gun is mounted so as to be movable up and down, extends across the width direction of the table electrode, and the portal frame is moved in the vertical direction on the table electrode according to the program. Detecting and inputting this to the electronic control mechanism as a vertical movement displacement on the table electrode of the welding gun, while detecting the movement displacement of the welding gun moving along the portal frame. The welding gun is input to the electronic control mechanism as a lateral displacement on the table electrode of the welding gun, the welding gun is positioned on the table electrode, and the positioned welding spot The welding gun is lowered from the portal frame by a command from the electronic control mechanism, and welding of one welding point is completed when the load current at the time of pressurization reaches a set value. Auto Pot welding method.   In the portal frame that runs in the longitudinal direction of the table electrode, both legs are individually driven by a servomotor, and the rotation speed of these servomotors is individually controlled by the electronic control mechanism. The electronic control mechanism performs processing based on the input data and sends a control signal to the portal frame so as to move in accordance with the horizontal direction perpendicular to the vertical direction of the table electrode. The automatic spot welding method according to claim 1, wherein the feeding is performed.   The automatic spot welding method according to claim 1 or 2, wherein a rotation angle at which the rod-shaped gun rotates about an axis thereof is input to the electronic control mechanism to obtain one position information of a welding spot.   Prior to welding, a material to be welded is placed on the table electrode, and the welding gun is manually moved in accordance with its shape and structure, and a moving path passing through a desired welding point is input. The automatic spot welding method according to claim 1, 2, or 3. 5. The automatic spot welding method according to claim 1, wherein a completion signal is sent to the electronic control mechanism when a load current during pressurization in welding at one welding spot reaches a set value.

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