JP5853113B1 - Welding apparatus and welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply an electrode tip or its tip to a workpiece to be welded provided with a large number of parts to be welded having a limited space for the electrode tip and its supporting portion to enter like a minimum flange with the same welding gun. Spot welding can be performed while avoiding the support portion from interfering with a portion other than the welding target portion of the workpiece. In a welding apparatus for sandwiching a workpiece to be welded between opposing electrode tips and spot welding, when the workpiece is sandwiched between opposing electrode tips, the electrode tip or a support portion thereof is a welding target of the workpiece. The opposing electrode tips are moved relative to each other in a direction perpendicular to their central axes so as not to interfere with other parts. [Selection] Figure 1

Description

  The present invention relates to a welding apparatus and a welding method for spot welding a portion to be welded, such as a flange whose width dimension is set to a minimum level, where the space for access by an electrode tip and its support portion is limited.

  In the spot welding, in order to stabilize the welding quality, as shown in FIG. 10A, when the spot welding part P set on the flange F of the workpiece W is sandwiched, the paired electrode tips 50, 60 are used. Is generally arranged so that the central axis lines (shown by alternate long and short dash lines) coincide with each other. However, due to design requirements, the width of the flange F may be set to the minimum dimension that can ensure the required nugget diameter. When spot-welding to such a minimum flange, as shown in FIG. 10 (b), the electrode tip 50 and the shank which is the support portion interfere with the work piece W at a portion other than the spot-welded portion P, This causes the inconvenience that spot welding cannot be performed.

  As a means for solving such inconvenience, for example, as shown in FIG. 10C, a structure in which the central axes of the pair of electrode chips 50, 60 are shifted (see, for example, Patent Document 1) is adopted. A method of missing the shank in advance can be considered. Even if the center axis of the pair of electrode tips 50.60 is deviated, if the top of one electrode tip 50 is made flat, the center of the other electrode tip 60 may be convex, even if the top is convex. As long as it does not deviate from the top, there will be no inconvenience such as slippage in the lateral direction during clamping pressurization.

JP-A-5-285666

  By the way, in the case where the workpiece is a large member constituting a car body or the like of the automobile, the shape is complicated, and a spot welding site is also set. Therefore, a method is adopted in which a welding gun is attached to the tip of the robot arm and each welding site is welded in accordance with a pre-programmed sequence / content. In this case, depending on the position of the spot welding site, the orientation of the gun arm that accesses the spot welding portion naturally varies (FIG. 11). For example, when spot welding parts P set in large numbers along the longitudinal direction of the flange are sequentially welded, the direction of the gun arm G is substantially the same as the flange F as shown in FIG. It may be orthogonal, or it may intersect diagonally as shown in FIG. 11 (b) or FIG. 11 (c).

  Here, considering the case where spot welding is performed with the welding gun of the robot arm on the minimum flange of FIG. 10 (c) described above, when the gun arm G is orthogonal to the flange, as shown in FIG. If the opposing electrode tip 60 is shifted to the tip side of the gun arm G with respect to the tip 50, spot welding can be performed while sandwiching the center of the flange F in the width direction. However, in the welding gun in which the electrode tips are shifted as in FIG. 12 (a), when the gun arms G cross diagonally, as shown in FIGS. 12 (b) and 12 (c), actual spot welding is performed. The part is detached from the flange F. Therefore, there is a problem that it is difficult to adopt a design in which a large number of parts to be welded are provided along the minimum flange.

  In the present invention, in view of such circumstances, the same welding gun is used for an object to be welded having a large number of spot welded parts where the space for accessing the electrode tip and its support part is restricted like a minimum flange, Provided are a welding apparatus and a welding method capable of welding while avoiding interference between an electrode tip or a support portion thereof and a portion other than a spot welding portion.

  According to a first aspect of the present invention, there is provided a welding apparatus that performs spot welding by sandwiching an object to be welded by opposing electrode tips, and includes a moving mechanism that relatively moves the opposing electrode tips in a direction perpendicular to the central axis thereof. A characteristic welding apparatus is provided.

  According to a second aspect of the present invention, there is provided a welding apparatus for spot welding by sandwiching a workpiece to be welded between opposing electrode tips, wherein when the workpiece is clamped by an electrode tip, the electrode tip and its supporting portion are the workpiece to be welded. In order not to interfere with any part other than the spot welding part, a moving mechanism is provided that moves one of the opposing electrode tips in a direction orthogonal to the central axis thereof to change the relative positional relationship with the other electrode tip. A welding apparatus is provided.

  According to a third aspect of the present invention, the moving mechanism includes a rotation output mechanism, a drive pin connected to the rotation output shaft of the rotation output mechanism, and a holder bracket that supports an electrode chip, and the drive pin is rotated in the rotation direction. The welding according to claim 1 or 2, wherein the holder bracket is revolved around the rotation output shaft to move the electrode tip by connecting the holder bracket at a portion eccentric from the output shaft. Providing equipment.

  The invention according to claim 4 is characterized in that the drive pin and the holder bracket are connected so as to be relatively rotatable, and a detent for preventing rotation of the holder bracket is provided. I will provide a.

  According to a fifth aspect of the present invention, there is provided a welding method characterized in that spot welding is performed using the welding apparatus according to any one of the first to fourth aspects.

  According to the present invention, in a welding apparatus and a welding method for sandwiching an object to be welded with opposed electrode tips and spot welding, the space around the spot welded part is restricted, and the electrode axes are aligned by matching the central axes. When arranged, when the electrode tip and its supporting part (shank, screw adapter, electrode holder, etc.) interfere with parts other than the spot welded part, the relative positional relationship between the opposing electrode tips is changed so as not to interfere. An excellent effect can be obtained. As a result, it is possible to reduce the design constraints that have arisen in order to secure the spot welding space in the sheet metal product.

  The moving mechanism has a structure in which the holder bracket is connected to the drive pin connected to the rotation output shaft at a position eccentric from the rotation output shaft, so that the electrode tip supported by the holder bracket revolves around the rotation output shaft. Therefore, it is possible to obtain an excellent effect that the relative positional relationship with the opposing electrode tip can be changed only by controlling the rotation phase of the rotation output shaft.

  The moving mechanism is provided with a detent that restricts the holder bracket from rotating, so the direction of the power cable connected to the electrode tip is constant, and it will not interfere with or be pulled by other parts or the workpiece. The cable processing can be easily performed.

The figure which shows the welding apparatus which becomes an example of embodiment of this invention. The perspective view which shows the moving mechanism of the said welding apparatus. The disassembled perspective view of an electrode tip shift mechanism among the said movement mechanisms. FIG. 3 is a cross-sectional view corresponding to AA in FIG. 2. The figure explaining an internal operation state with the BB cross-section equivalent figure of FIG. FIG. 5 is a view for explaining an internal operation state in the CC cross-sectional view of FIG. 4. The figure explaining the relative position movement of the electrode tip by the said moving mechanism (The figure which showed the positional relationship of the electrode tip which opposes in the direction of a center axis line, and the direction orthogonal to it). The figure explaining the condition which performs spot welding using the said moving mechanism. The figure which shows the welding apparatus which becomes another example of embodiment of this invention. The figure explaining the means for spot welding to the minimum flange. The figure explaining the condition welded with the welding gun attached to the robot arm. The figure explaining the subject of a prior art.

  A welding apparatus which is an example of an embodiment of the present invention will be described below with reference to the drawings.

(Outline of welding apparatus 1 according to an embodiment of the present invention)
As shown in FIG. 1, the welding apparatus 1 is mainly a C-shaped fixed arm 2, a movable arm 3, a drive unit 4 that reciprocates the movable arm 3, and a fixed arm 2 and a movable arm. A pair of fixed electrode chip 51 and movable electrode chip 61 supported by arm 3 and facing each other, and a frame connected to fixed arm 2 and drive unit 4 and attached to a robot arm (not shown) to support the entire apparatus. 7 and a power supply unit 71 that is fixed to the frame 7 and supplies power to the electrode chip.

(Fixed arm 2)
As shown in FIG. 1, the fixed arm 2 includes an electrode holder 22 having a rectangular cross section at the tip of a fixed arm body 21 bent in a substantially C shape. A screw adapter 52 and a shank 53 are attached straight to the tip of the electrode holder 22 so as to form an L shape with the electrode holder, and a fixed electrode tip 51 is supported on the tip of the shank 53.

(Movable arm 3)
As shown in FIG. 1, the movable arm 3 includes a moving mechanism 8 and an electrode holder 31 attached to the distal end thereof. The moving mechanism 8 is connected to a drive rod (not shown) of the drive unit 4 and is movable. The entire arm 3 reciprocates with respect to the fixed arm 2 by reciprocating integrally with the drive rod. A screw adapter 62 and a shank 63 are attached straight to the tip of the electrode holder 31, and the movable electrode tip 61 is supported on the tip of the shank 63.

(Fixed electrode tip 51, movable electrode tip 61)
The fixed electrode tip 51 and the movable electrode tip 61 are arranged opposite to each other, and the movable arm 3 can reciprocate with respect to the fixed arm 2 so as to approach and separate from each other. Spot welding is performed by power feeding from the power feeding unit 71 in a state where the spot welded portion of the welded product is sandwiched and the sheet metal panels that are overlaid are pressed.

  Incidentally, the center axis of the fixed electrode tip 51 and the movable electrode tip 61 do not coincide with each other, and as shown by the symbol X in FIG. 1, a deviation of about 3 to 5 mm is provided in the direction orthogonal to the center axis. This misalignment X is preliminarily performed so that the electrode tip and its supporting portion (shank, screw adapter, electrode holder, etc.) do not interfere with a portion other than the spot welded portion when spot welding is performed on a spot welded portion having a narrow peripheral space. It is provided for escape.

  On the other hand, since the direction in which the electrode tip should escape depends on the workpiece shape around the spot welded part and the direction in which the welding gun accesses the spot welded part, the relative positional relationship (displacement) between the electrode tips is fixed. Therefore, the applicable range of the welding gun is limited. Therefore, a moving mechanism 8 that incorporates a movable electrode tip 61 in a direction orthogonal to the central axis thereof to enable relative movement of the fixed electrode tip 51 and the movable electrode tip 61 in a direction orthogonal to the central axis is incorporated. The relative positional relationship can be changed and set. Below, the moving mechanism 8 is demonstrated based on FIGS.

(Movement mechanism 8)
As shown in FIG. 2, the moving mechanism 8 is formed by connecting an electrode tip shift mechanism 81 and a rotation output mechanism 91 in series. The rotation output mechanism 91 is formed by connecting a speed reducer 93 to a motor 92, and the output rotation of the motor 92 is decelerated by the speed reducer 93, and the electrode tip shift mechanism 81 is connected via a rotation output shaft provided in the speed reducer 93. To communicate. The rotation output shaft provided in the speed reducer 93 is set so that the fixed electrode tip 51 and the central axis coincide with each other. As the motor 92, a servo motor, a stepping motor, an induction motor, an air motor or other motors capable of positioning control are used. Next, the electrode tip shift mechanism 81 will be described.

(Electrode tip shift mechanism 81)
First, the operation of the electrode tip shift mechanism 81 will be briefly described. As shown in FIGS. 3 and 4, the electrode tip shift mechanism 81 includes a drive pin 83 connected to the rotation output shaft of the speed reducer 93 and a holder bracket 84 connected to the drive pin 83. As shown in FIG. 4, the drive pin 83 is connected to the holder bracket 84 at a position eccentric from the center axis of the rotation output shaft by a distance X (the same dimension as the above-mentioned deviation X), and the rotation output shaft is When rotated, the holder bracket 84 revolves around the center axis of the rotation output shaft with the distance X as the rotation radius.

  Similarly, the electrode holder 31 held by the holder bracket 84, the screw adapter 62, the shank 63, and the movable electrode chip 61 revolve around the rotation output shaft of the speed reducer 93. As described above, the central axis of the fixed electrode chip 51 Is coincident with the rotational output shaft of the speed reducer 93, so that the movable electrode tip 61 can be relatively moved in all directions around 360 ° around the central axis 51a of the fixed electrode tip 51, as shown in FIG. . That is, the fixed electrode tip 51 and the movable electrode tip 61 can freely change the relative positional relationship while maintaining the distance X between the center axis lines 51a and 61a at a constant dimension X in the direction orthogonal to the center axis lines 51a and 61a. Has the effect of being Needless to say, the dimension of the deviation X should be set within a range in which the top of the movable electrode tip 61 does not deviate from the top of the fixed electrode 51.

(Base bracket 82)
As shown in FIGS. 3 to 6, the electrode tip shift mechanism 81 is configured by housing a base bracket 82 formed in a substantially rectangular parallelepiped shape as a main body and housing each component therein. The base bracket 82 is formed with a first accommodation hole 821 (FIGS. 4 and 6) and a second accommodation hole 822 (FIGS. 3 and 4) on two surfaces located on the front and back sides. These accommodation holes 821 and 822 are all formed in a right cylindrical shape and concentric, and are partitioned by a partition wall 823 having a constant thickness. A through hole 824 having a circular cross section is formed at the center of the partition wall 823, and four guide holes 825 (FIGS. 3 and 5) having a circular cross section are shifted by 90 degrees around the through hole 824. Are formed at regular intervals.

  The first accommodation hole 821 accommodates a drive pin 83 connected to the speed reducer 93 (rotation output mechanism 91), and the opening is closed by screwing the speed reducer 93 to the base bracket 82. . The second accommodation hole 822 accommodates the holder bracket 84, the bearing 85, the washer 86, and the washer 87 (not shown in FIG. 3). The opening is covered by fixing the cover 88 to the base bracket 82 with screws. ing.

  As shown in FIG. 4, the pin portion 831 of the drive pin 83 accommodated in the first accommodation hole 821 passes through the through hole 824, and the tip protrudes into the second accommodation hole 822, so that the second accommodation A holder bracket 84 accommodated in the hole 822 is connected via a bearing 85 so as to be relatively rotatable. As shown in FIG. 5, the through hole 824 is formed in a size that does not interfere even if the pin portion 831 revolves. As shown in FIGS. 5A to 5D, four guide pins 843 (FIG. 3) provided on the holder bracket 84 are respectively engaged with the guide holes 825, and the holder bracket 84 is driven. When the pin 83 is revolved, the movement is guided to restrict the holder bracket 84 from rotating as shown in FIGS. As a result, the movable electrode tip 61 rotates and a cable (not shown) connected to the movable electrode tip 61 moves greatly to interfere with an object to be welded, other apparatus / jigs, or other parts of the welding apparatus 1. And problems such as breakage due to cable pulling are prevented.

(Drive pin 83)
As shown in FIGS. 3 and 4, the drive pin 83 has a substantially disk-shaped main body, and one of the disk surfaces has the same distance as the above-described deviation X from the center axis of the disk. A pin portion 831 protruding at an eccentric position is provided. The inner peripheral surface of the bearing 85 is fitted to the stepped portion at the tip of the pin portion 831. Further, on the opposite disk surface, there is an inlay 832 (FIG. 4) formed concentrically with the central axis, and the drive pin 83 is concentrically combined with the rotation output shaft of the rotation output mechanism 91 by the inlay 832. In this state, they are connected with screws. As a result, when the drive pin 83 is rotated by the rotation output shaft of the rotation output mechanism 91, the pin portion 831 revolves around the rotation output shaft with the rotation radius X, and the holder bracket 84 connected to the tip also rotates. Revolve with radius X.

(Holder bracket 84)
The holder bracket 84 has a substantially disc-shaped main body portion, and on one disc surface thereof, a holder pin portion 841 concentric with the main body portion is provided so as to protrude, and the disc on the opposite side is provided. A fitting hole 842 (FIG. 4) for fitting with the outer peripheral surface of the bearing 85 that fits to the drive pin 83 is formed on the surface, and four guide pins 843 are provided around the fitting hole 842. Are provided so as to protrude at equal intervals by shifting the angle by 90 degrees. The holder pin portion 841 holds the electrode holder 31 (FIG. 1), and as a result, the electrode holder 31, the screw adapter 62, the shank 63, and the movable electrode tip 61 revolve as described above. Further, the distance between the central axes of the holder pin portion 841 and the guide pin 843 is set so as to substantially match the distance between the central axes of the through hole 824 (drive pin 83) and the guide hole 825, and the guide pin 842 Is set so as to be substantially equal to the dimension obtained by subtracting the distance of the deviation X from the radial distance of the guide hole 825, so that the holder bracket 84 is attached to the electrode tip shift mechanism main body as shown in FIG. Revolves in a state where the direction is fixed (does not rotate). In addition, if it is set to the said dimension relationship, the guide pin (and guide hole) does not need to be four (four), and if it is three (three) or more, it can regulate so that it may not rotate.

(Cover 88)
As shown in FIGS. 2 to 4, the cover 88 that covers the opening of the second accommodation hole 822 is formed with a through hole 881 that allows the holder pin portion 841 of the holder bracket 84 to penetrate and protrude outside the mechanism. . The through hole 881 is formed in such a size that the holder bracket 84 does not come out of the second accommodation hole 822 and does not interfere even if the holder pin portion 841 revolves. In the holder bracket 84, a washer 86 is attached to the disc surface facing the partition wall 823, and a washer 87 is attached to the disc surface facing the cover 88 on the opposite side. In a state where the main body portion is sandwiched between the partition wall 823 and the cover 88, the electrode tip shift mechanism main body can slide without causing rattling and can smoothly revolve.

(Spot welding method using the welding apparatus 1)
Here, the welding apparatus 1 is attached to the tip of the robot arm, and the fixed electrode tip 51 and the movable electrode tip 61 are accessed from various angles with respect to the minimum flange F in the same manner as described with reference to FIG. A method of welding will be described. As shown in FIG. 8A, when accessing the fixed arm 2 so as to be orthogonal to the flange F, the movable electrode chip 61 facing the fixed electrode chip 51 is moved to the distal end side of the fixed arm 2. By moving it, the center of the flange F in the width direction can be clamped and spot-welded while the fixed electrode tip 51 and its supporting portion are retracted so as not to interfere with the workpiece. At this time, the inside of the electrode tip shift mechanism 81 is as shown in FIGS. 5C and 6C, and the pin portion 831 and the holder bracket 84 of the drive pin 83 are closer to the upper side (lower side in FIG. 1). )

  Further, when accessing the flange F so that the fixed arm 2 crosses obliquely, the moving mechanism 8 is operated to cause the movable electrode tip 61 to revolve around the central axis of the fixed electrode tip 51. As shown in FIG. 8B and FIG. 8C, the frame F, the fixed electrode chip 51 and the movable electrode chip 61 are arranged in the same positional relationship as in FIG. Spot welding can be performed by sandwiching the center in the width direction of the flange F while retracting the support portion so as not to interfere with the workpiece W. Since the movable electrode chip 61 can move in any direction of 360 degrees around the fixed electrode chip 51 while maintaining a certain distance X, the angle of the fixed arm 2 with respect to the frame F is set in any way. Can also respond. The inside of the electrode tip shift mechanism 81 is as shown in FIG. 5B and FIG. 6B in the case of FIG. 8B, and in FIG. This is as shown in FIG.

(Modification of the above embodiment)
The welding apparatus 1 is a C-type spot gun apparatus equipped with a moving mechanism 8 that moves the electrode tip 61 in a direction perpendicular to the axis thereof, but may be another type of spot gun apparatus. For example, as shown in FIG. 9, by attaching a moving mechanism similar to the moving mechanism 8 to one arm of the X-type spot gun device, and holding the electrode holder to be held by the arm in the moving mechanism, The electrode tip supported by the electrode holder may be movable in a direction orthogonal to the central axis.

  In the above embodiment, the movable arm 3 is provided with the moving mechanism 8 and the movable electrode tip 61 supported by the movable arm 3 is moved in the direction perpendicular to the central axis thereof. It is also possible to change the relative positional relationship with the movable electrode chip by providing and moving the fixed electrode chip with a moving mechanism. Alternatively, both the opposing electrode tips may be supported by different moving mechanisms, and the movements of the opposing electrode tips may be combined. In such a case, not only the displacement direction of both electrode tips changes as in the above embodiment, but also the distance between the electrode tips in the direction orthogonal to the central axis can be changed, so that the corresponding range can be expanded. it can.

  In the above embodiment, the top of the fixed electrode chip 51 is formed in a flat shape, while the top of the movable electrode chip 61 is formed in a convex shape. Instead, the top of the fixed electrode chip 51 is formed in a convex shape. On the other hand, it does not prevent the top of the movable electrode chip 61 from being formed into a flat shape, or the top of the opposing electrode chip from being formed into a flat or convex shape.

Reference Signs List 1 welding apparatus 2 fixed arm 3 movable arm 4 drive unit 7 frame 8 moving mechanism 51 fixed electrode tip 61 movable electrode tip
81 Electrode tip shift mechanism 82 Base bracket 83 Drive pin 84 Holder bracket 85 Bearing 86 Washer 87 Washer 91 Rotation output mechanism 93 Reducer

Claims (5)

  A welding apparatus for spot welding by sandwiching an object to be welded between opposing electrode tips, comprising a moving mechanism for relatively moving the opposing electrode tips in a direction perpendicular to the central axis thereof.   In a welding apparatus that sandwiches an object to be welded with opposing electrode tips and performs spot welding, when the object to be welded is sandwiched between electrode tips, the electrode tip and its supporting portion are parts other than the spot welded part of the object to be welded. A welding apparatus comprising: a moving mechanism that moves one of the opposing electrode tips in a direction orthogonal to the central axis thereof so as to change a relative positional relationship with the other electrode tip so as not to interfere with the other electrode tip.   The moving mechanism includes a rotation output mechanism, a drive pin coupled to the rotation output shaft of the rotation output mechanism, and a holder bracket that supports an electrode chip, and the drive pin is located at a portion eccentric from the rotation output shaft. The welding apparatus according to claim 1 or 2, wherein the holder bracket revolves around the rotation output shaft to move the electrode tip by connecting the holder bracket.   The welding device according to claim 3, wherein the drive pin and the holder bracket are connected to each other so as to be relatively rotatable, and a detent is provided to prevent rotation of the holder bracket.   Spot welding using the welding apparatus in any one of Claims 1 thru | or 4 characterized by the above-mentioned.

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