JP5864363B2 - Resistance welding apparatus and resistance welding method - Google Patents

Description

  The present invention relates to a resistance welding apparatus and a resistance welding method. More specifically, the present invention relates to a resistance welding apparatus and a resistance welding method for resistance welding a workpiece in which a plurality of plate materials are overlapped.

  Conventionally, resistance welding is used for joining workpieces in which a plurality of plate materials are stacked. In resistance welding, the superimposed workpieces are pressed between a pair of main electrodes, and a main current is passed between the main electrodes in a state in which a predetermined pressure or more is maintained. Then, the work material is melted by Joule heat generated by energization, and a nugget that is a melt of the plate material is generated at the interface of the plate material between the main electrodes. Thereafter, by stopping energization while maintaining the pressurized state, the nugget is cooled and solidified, and the plate material is welded.

  For example, in the automobile field or the like, a work is used in which a plurality of thick and hard high-tensile steel plates are stacked, and further, thin and soft soft steel plates are stacked. When such a workpiece is resistance welded, the nugget between the thinnest plate material located outside the workpiece and the adjacent plate material does not grow sufficiently, and the thinnest plate material and the adjacent plate material cannot be joined sufficiently. There is. Therefore, a technique is known in which an auxiliary electrode is provided on the thinnest plate material side and brought into contact with a workpiece, and an auxiliary current is passed from the main electrode to the auxiliary electrode as well as between the main electrodes. According to this technique, the growth of the nugget can be promoted by the auxiliary current on the thinnest plate material side.

  In addition, during resistance welding, a so-called reactive current may flow between plate members other than the welded portion, and the reactive current may inhibit nugget growth at the welded portion, and the plate members may not be sufficiently joined together. Therefore, for example, a technique has been proposed in which an auxiliary electrode is provided so as to surround the main electrode, and a main current flows between the main electrodes while the auxiliary electrode is in contact with the work, and an auxiliary current flows from the main electrode to the auxiliary electrode. (See Patent Document 1). According to this technique, the potential around the welded portion is increased by the auxiliary current without heating the workpiece in advance. As a result, the reactive current is suppressed and the growth of the nugget at the welded portion can be promoted.

JP 2011-194465 A

  By the way, in resistance welding, when a large current is passed as the main current, the heat capacity of the main electrode is small, so that the main electrode is in a considerably high temperature state due to heat generation during energization. Further, since the main electrode is in a considerably high temperature state, it takes a long time for the temperature of the main electrode to sufficiently decrease even after the current supply is cut off. Therefore, there is a problem that the main electrode is deteriorated and the life is shortened.

  This invention is made | formed in view of the above, The objective is to provide the resistance welding apparatus and resistance welding method which can suppress that a main electrode will be in a high temperature state, and can prolong the life of a main electrode.

  In order to achieve the above object, the present invention provides a work (for example, a work W described later) obtained by superposing a plurality of plate materials (for example, a plate material W1 (thin plate), W2 (thick plate), W3 (thick plate) described later). A resistance welding apparatus (for example, a spot welding apparatus 1 to be described later) for resistance welding, and a first main electrode (for example, a first main electrode 121 to be described later) that contacts the workpiece is opposite to the first main electrode. A second main electrode (for example, a second main electrode 131 described later) that contacts the workpiece from the side and has a polarity opposite to that of the first main electrode; and the first main electrode and the second main electrode An auxiliary electrode (for example, auxiliary electrodes 122 and 122 described later) that is in contact with the workpiece and has a polarity opposite to that of the first main electrode, adjacent to one of the main electrodes, the first main electrode, The workpiece is clamped by the second main electrode and the auxiliary electrode In a pressed state, a main current (for example, a main current D1 described later) flows between the first main electrode and the second main electrode, and an auxiliary current flows between the first main electrode and the auxiliary electrode. (For example, a control device 100, a power supply, and a variable resistor, which will be described later) for passing a current (for example, an auxiliary current D2 described later) Thus, heat capacity increasing means for increasing the heat capacity of the main electrode (for example, a control device 100 described later, contact portions 124 and 124, first cylinder mechanisms 127 and 127, rotating shafts 125 and 125) is provided. A resistance welding apparatus is provided.

In the present invention, first, a main current is passed between main electrodes, and an auxiliary current is passed between the main electrode and the auxiliary electrode, and then the auxiliary current is cut off. Here, in resistance welding, a large current is usually passed through the main electrode, while a small current is passed through the auxiliary electrode. The heat capacity of both the main electrode and the auxiliary electrode is small. At the time when the auxiliary current was cut off, a large current was flowing or the flowing main electrode was in a considerably high temperature state, but a small current was flowing. The electrode is at a lower temperature than the main electrode.
Therefore, in the present invention, after the auxiliary current is interrupted, the auxiliary electrode in the low temperature state is brought into contact with the adjacent main electrode in the high temperature state to increase the heat capacity of the main electrode. As a result, when the main current is energized at the time when the auxiliary current is interrupted, the temperature rise of the main electrode can be suppressed, and when the energization of the main current is interrupted, the main electrode is cooled. Can promote. Therefore, according to this invention, it can suppress that a main electrode becomes a high temperature state, and can extend the life of a main electrode.

In particular, when the auxiliary electrode is brought into contact with the workpiece from the thinnest plate side adjacent to the first main electrode, and the auxiliary current is supplied to the thinnest plate material side to promote nugget growth, the main electrode has a center of heat generation. The effect of the present invention is enhanced when the amount of heat transfer to the main electrode is large in the vicinity.
Further, for example, in order to weld a narrow portion such as a mohawk portion of an automobile, the effect of the present invention is enhanced even when the main electrode has a small diameter and a particularly small heat capacity. In addition, since the diameter of the main electrode is limited in welding of the mohawk part, and the clearance around the main electrode at the time of welding is limited, it has been impossible to take measures to simply increase the diameter of the main electrode in the past, According to the present invention, since the auxiliary electrode can be brought close to and brought into contact with the main electrode from the Mohawk groove direction, there is no restriction as in the prior art.
According to the present invention, since the auxiliary electrode is in contact with the main electrode, the conventional main electrode can be used as it is. Therefore, the chip dressing of the main electrode does not become difficult as in the case where a member for increasing the heat capacity is attached to the main electrode.

  The present invention also provides resistance welding for resistance welding of a workpiece (for example, workpiece W described later) in which a plurality of plate materials (for example, plate materials W1 (thin plate), W2 (thick plate), W3 (thick plate) described later) are overlapped. A first main electrode (for example, a first main electrode 121 described later) is brought into contact with the workpiece, and a second main electrode (for example, a first main electrode described later) having a polarity opposite to that of the first main electrode. 2 main electrodes 131) are brought into contact with the workpiece from the side opposite to the first main electrodes, and auxiliary electrodes having a polarity opposite to that of the first main electrodes (for example, auxiliary electrodes 122 and 122 described later) are The first main electrode and the second main electrode are brought into contact with the work adjacent to one of the main electrodes, and the work is moved by the first main electrode, the second main electrode, and the auxiliary electrode. Between the first main electrode and the second main electrode; An energization step of flowing a main current (for example, a main current D1 described later) and flowing an auxiliary current (for example, an auxiliary current D2 described later) between the first main electrode and the auxiliary electrode, and cutting off the auxiliary current And a heat capacity increasing step of increasing the heat capacity of the main electrode by bringing the auxiliary electrode into contact with the adjacent main electrode, thereby providing a resistance welding method.

  According to the invention of the resistance welding method, the same effect as that of the invention of the resistance welding apparatus can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that a main electrode becomes a high temperature state, and can provide the resistance welding apparatus and resistance welding method which can prolong the life of a main electrode.

It is a side view which shows the structure of the spot welding apparatus which concerns on one Embodiment of this invention. It is a side view which shows the structure of the movable electrode part of the spot welding apparatus which concerns on the said embodiment. It is a perspective view which shows the structure of a pair of auxiliary electrode which concerns on the said embodiment. It is a side view which shows a state when a pair of auxiliary electrode which concerns on the said embodiment is made to contact | abut to a 1st main electrode. It is a top view which shows a state when applying the spot welding apparatus which concerns on the said embodiment to welding of a mohawk part, and making a pair of auxiliary electrode contact | abut to a 1st main electrode.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a side view showing a configuration of a spot welding apparatus 1 as a resistance welding apparatus according to an embodiment of the present invention. The spot welding apparatus 1 according to the present embodiment is an electric spot welding apparatus attached to the tip of a robot arm 80.
The spot welding apparatus 1 presses a workpiece W obtained by superposing three plate materials W1 (thin plate), W2 (thick plate), and W3 (thick plate) between a first main electrode and a second main electrode described later. In this state, the work W is welded by energizing between these main electrodes.

  The spot welding apparatus 1 includes a spot welding gun 10 supported by a support portion 90 provided at the tip of a robot arm 80 and a control device 100 that controls the spot welding gun 10.

  The support part 90 includes a support bracket 91. The support bracket 91 includes an upper plate 91a and a lower plate 91b parallel to the upper plate 91a. A guide bar 92 is bridged between the upper plate 91a and the lower plate 91b.

  A support plate 93 slidable in the axial direction is attached to the guide bar 92. The support plate 93 extends in parallel to the upper plate 91a and the lower plate 91b from the robot arm 80 side, and supports the spot welding gun 10 on the tip side. A casing-like support body 94 is provided on the upper surface on the base end side of the support plate 93. A first coil spring 95 wound around the guide bar 92 is interposed between the upper plate 91a and the support 94. Similarly, a second coil spring 96 wound around the guide bar 92 is interposed between the lower plate 91 b and the support plate 93.

The spot welding gun 10 can be moved up and down relative to the support portion 90 by being supported by the support plate 93. The spot welding gun 10 includes a welding gun main body 11 and an electrode portion 15 provided at the tip of the welding gun main body 11.
The welding gun body 11 includes a servo motor 16 provided on the upper portion thereof, and a feed screw mechanism (not shown) connected to the servo motor 16.
The electrode unit 15 includes a movable electrode unit 120 and a fixed electrode unit 130.

  The movable electrode portion 120 protrudes downward from the tip of the welding gun body 11 and is supported by the tip of the rod 12 connected to the feed screw mechanism. The movable electrode portion 120 can move forward and backward with respect to the fixed electrode portion 130 to be described later when the rod 12 moves up and down (moves in the A2 direction or the A1 direction in FIG. 1) via the feed screw mechanism by the servo motor 16. ing. The movable electrode unit 120 includes a first main electrode 121 and a pair of auxiliary electrodes 122 and 122 provided adjacent to each other with the first main electrode 121 interposed therebetween.

The fixed electrode portion 130 is supported by the tip of the C-shaped yoke 13 that extends downward from the connecting portion 14 connected to the tip of the welding gun body 11. The fixed electrode unit 130 includes a second main electrode 131.
The movable electrode portion 120 and the fixed electrode portion 130 are disposed to face each other with the workpiece W interposed therebetween.

FIG. 2 is a side view showing the configuration of the movable electrode portion 120 of the spot welding apparatus 1 according to the present embodiment. As shown in FIG. 2, the first main electrode 121 and the pair of auxiliary electrodes 122, 122 included in the movable electrode unit 120 are arranged along the surface direction of the workpiece W at predetermined intervals.
The first main electrode 121 has a cylindrical shape, and its tip has a dome shape (spherical shape). The first main electrode 121 has substantially the same diameter as the second main electrode 131. The first main electrode 121 is disposed to face the second main electrode 131 with the work W interposed therebetween, and the work W is pressed and sandwiched by the first main electrode 121 and the second main electrode 131.

The auxiliary electrode 122 includes an L-shaped auxiliary electrode main body 123 and an abutting portion 124 that is provided on the distal end side of the auxiliary electrode main body 123 and contacts the first main electrode 121.
The auxiliary electrode main body 123 includes a columnar vertical portion 123A disposed on the distal end side thereof, and a columnar horizontal portion 123B disposed on the proximal end side. The tip of the vertical portion 123A has a dome shape (spherical shape), and the diameter thereof is smaller than that of the first main electrode 121 and the second main electrode 131. The workpiece W is also pressurized by the vertical portions 123A and 123A of the pair of auxiliary electrodes 122 and 122.

  The connecting portion between the vertical portion 123A and the horizontal portion 123B is provided with a rotation shaft 125 in a direction substantially orthogonal to the axial direction of the vertical portion 123A and substantially orthogonal to the axial direction of the horizontal portion 123B. The pair of auxiliary electrodes 122 and 122 are pivotally supported by the movable electrode main body 126 by the rotation shafts 125 and 125 so as to be rotatable toward the first main electrode 121 side.

  A first cylinder mechanism 127 is provided on the base end side of the horizontal portion 123B to press the base end side of the horizontal portion 123B toward the workpiece W (downward in FIG. 2). The tip of the rod portion 127A of the first cylinder mechanism 127 is formed in a dome shape (spherical shape). Thereby, the auxiliary electrode 122 is moved forward by the rod portion 127A by the driving force of the first cylinder mechanism 127 and presses the base end side of the horizontal portion 123B downward, so that the distal end side of the vertical portion 123A is the first side. It can be rotated in a direction approaching the one main electrode 121 side. The first cylinder mechanism 127 is controlled by the control device 100.

  Further, in the vertical portion 123A, the upper side of the contact portion 124 is connected to the movable electrode portion main body 126 via a coil spring. As a result, when the driving force of the first cylinder mechanism 127 is applied, the auxiliary electrode 122 rotates in a direction in which the front end side of the vertical portion 123A approaches the first main electrode 121 side against the biasing force of the coil spring 129. Move. In addition, when the driving force of the first cylinder mechanism 127 is released, the auxiliary electrode 122 rotates in a direction in which the leading end side of the vertical portion 123A is separated from the first main electrode 121 by the urging force of the coil spring 129. Return to position.

  In addition, the movable electrode portion main body 126 has a second cylinder mechanism 128 that allows the movable electrode portion main body 126 and the pair of auxiliary electrodes 122 and 122 to advance and retreat with respect to the workpiece W independently of the first main electrode 121. Is provided. Accordingly, the pair of auxiliary electrodes 122 and 122 can be advanced and retracted with respect to the workpiece W independently of the first main electrode 121 by the driving force of the second cylinder mechanism 128. That is, the pair of auxiliary electrodes 122 and 122 can be moved up and down relative to the first main electrode 121. Note that the second cylinder mechanism 128 is controlled by the control device 100.

  FIG. 3 is a perspective view showing a configuration of the pair of auxiliary electrodes 122 and 122 according to the present embodiment. As shown in FIG. 3, the contact portion 124 is a plate-like member extending in a substantially horizontal direction from the vertical portion 123 </ b> A of the auxiliary electrode body 123 toward the first main electrode 121. The front end portion of the contact portion 124 is formed to be inclined in a direction away from the first main electrode 121 toward the workpiece W side (downward). In addition, a semi-cylindrical recess 124 </ b> A corresponding to the outer peripheral shape of the first main electrode 121 is provided at the tip. As a result, when the pair of auxiliary electrodes 122 and 122 rotate toward the first main electrode 121, the tip end of the contact portion 124 is fitted to the outer periphery of the first main electrode 121. .

  FIG. 4 is a side view showing a state when the pair of auxiliary electrodes 122 and 122 according to the above embodiment are brought into contact with the first main electrode 121. As shown in FIG. 4, the pair of auxiliary electrodes 122 and 122 can turn toward the first main electrode 121 side until the tip surfaces of the contact portions 124 and 124 of the pair of auxiliary electrodes 122 and 122 come into contact with each other. It has become. At this time, the recesses 124 </ b> A and 124 </ b> A of the contact portions 124 and 124 are fitted to the outer periphery of the first main electrode 121, thereby increasing the heat capacity of the first main electrode 121. In the present embodiment, the contact portions 124 and 124 are made of the same material as the auxiliary electrode bodies 123 and 123, and are excellent in thermal conductivity.

Returning to FIG. 1, a power source (not shown) is connected to the movable electrode unit 120 and the fixed electrode unit 130 having the above-described configuration. Specifically, the positive electrode of the power source is connected to the first main electrode 121, and the negative electrode is connected to the second main electrode 131 and the pair of auxiliary electrodes 122 and 122. For this reason, the welding current flowing into the workpiece W from the power source through the first main electrode 121 is divided into a main current D1 going to the second main electrode 131 and auxiliary currents D2 and D2 going to the pair of auxiliary electrodes 122 and 122, respectively. Branch.
In addition, a variable resistor (not shown) is provided in each current path, and under the control of the control device 100, in addition to adjusting the current amount, energization can be started and interrupted.

In general, when a main current is applied only between the first main electrode 121 and the second main electrode 131, the resistance value of the thick plate tends to be large, so that the nugget grows biased toward W2 and W3. On the other hand, since the resistance value of W1, which is a thin plate, tends to be small, the contact resistance between W1 and W2 becomes small, and sufficient Joule heat cannot be generated between W1 and W2. It cannot be joined sufficiently.
In this respect, in the present embodiment, the main current D1 and the auxiliary currents D2 and D2 are branched and the welding current flows, so that the current density between W1 and W2 can be increased. As a result, the amount of heat input per unit volume between W1 and W2 also increases, and as a result of sufficient growth of the nugget between W1 and W2, sufficient bonding is possible.

Next, operation | movement of the spot welding apparatus 1 which concerns on this embodiment is demonstrated.
First, the spot welding gun 10 is moved to the welding site of the workpiece W by the operation of the robot arm 80 and the support unit 90 in a state where the movable electrode unit 120 is separated from the fixed electrode unit 130. Specifically, the spot welding gun 10 is moved to a position where the second main electrode 131 comes into contact with the lower surface of the welding portion of the workpiece W.

Next, the servo motor 16 is controlled by the control device 100, and the movable electrode portion 120 is advanced with respect to the workpiece W by the action of the feed screw mechanism. At this time, the auxiliary electrodes 122 and 122 of the movable electrode unit 120 are retracted in advance from the first main electrode 121.
Then, the tip of the first main electrode 121 comes into contact with the upper surface of the workpiece W. As a result, the workpiece W is pressed and clamped by the first main electrode 121 and the second main electrode 131.
Thereafter, the control device 100 controls the second cylinder mechanism 128 to advance the pair of auxiliary electrodes 122 and 122 relative to the workpiece W, and abuts each tip portion on the upper surface of the welded portion of the workpiece W. Thereby, the workpiece W is also pressurized by the pair of auxiliary electrodes 122 and 122.

  Next, the control device 100 controls the power source to supply a welding current. Then, a main current D1 flows from the first main electrode 121 toward the second main electrode 131, and auxiliary currents D2, D2 flow from the first main electrode 121 toward the pair of auxiliary electrodes 122, 122. As a result, the nugget grows between W2 and W3, and also between W1 and W2, the current density is increased by the main current D1 and the auxiliary currents D2 and D2, and the amount of heat input increases to promote the growth of the nugget. Is done.

  Next, when the nugget is sufficiently grown between W1 and W2, the control device 100 controls the power source and the variable resistance to cut off the auxiliary currents D2 and D2. As for the main current D1, energization is continued or interrupted according to the growth state of the nugget between W2 and W3. After the auxiliary currents D2 and D2 are cut off, the control device 100 controls the second cylinder mechanism 128 to retract the pair of auxiliary electrodes 122 and 122 with respect to the workpiece W, and the respective leading end portions are placed on the upper surface of the workpiece W. Separate from.

  Next, the control device 100 controls the first cylinder mechanisms 127 and 127 to rotate the pair of auxiliary electrodes 122 and 122 toward the first main electrode 121 about the rotation shafts 125 and 125. At this time, the pair of auxiliary electrodes 122 and 122 are rotated against the urging force of the coil spring 129 until the tip surfaces of the contact portions 124 and 124 of the pair of auxiliary electrodes 122 and 122 come into contact with each other. Then, the concave portions 124 </ b> A and 124 </ b> A of the contact portions 124 and 124 are fitted to the outer periphery of the first main electrode 121, so that the heat capacity of the first main electrode 121 is increased. Thereby, when the main current D1 is being energized, the temperature increase of the first main electrode 121 can be suppressed, and when the energization of the main current D1 is interrupted, the first main electrode 121 is cooled. Promoted.

  When the main current D1 is being energized, the control device 100 controls the power supply to stop the supply of the welding current. Next, the servo motor 16 is controlled by the control device 100 and the movable electrode portion 120 is moved backward with respect to the workpiece W by the action of the feed screw mechanism. As a result, the nugget is cooled and solidified, and the workpiece W is welded.

According to the spot welding apparatus 1 according to the present embodiment, the following effects are exhibited.
In the present embodiment, first, the main current D1 is passed between the first main electrode 121 and the second main electrode 131, and the auxiliary currents D2 and D2 are passed between the first main electrode 121 and the pair of auxiliary electrodes 122, 122. Thereafter, the auxiliary currents D2 and D2 are cut off. Here, in resistance welding, a large current is usually passed through the main electrode, while a small current is passed through the auxiliary electrode. The heat capacity of both the main electrode and the auxiliary electrode is small. At the time when the auxiliary current was cut off, a large current was flowing or the flowing main electrode was in a considerably high temperature state, but a small current was flowing. The electrode is at a lower temperature than the main electrode.
Therefore, in the present embodiment, after the auxiliary currents D2 and D2 are cut off, the pair of auxiliary electrodes 122 and 122 in a lower temperature state are brought into contact with the adjacent first main electrode 121 in the higher temperature state than the first main electrode 121. As a result, the heat capacity of the first main electrode 121 is increased. Accordingly, when the main current D1 is being energized at the time when the auxiliary currents D2 and D2 are interrupted, the temperature increase of the first main electrode 121 can be suppressed, and the energization of the main current D1 is interrupted. In addition, cooling of the first main electrode 121 can be promoted. Therefore, according to this embodiment, it can suppress that the 1st main electrode 121 becomes a high temperature state, and can extend the lifetime of the 1st main electrode 121. FIG.

In particular, in this embodiment, the auxiliary electrodes 122 and 122 are adjacent to the first main electrode 121 and are brought into contact with the work W from the thinnest plate W1 side, and the auxiliary currents D2 and D2 are supplied on the thinnest plate material W1 side to grow nuggets. The first main electrode 121 is in the vicinity of the heat generation center, and the amount of heat transferred to the first main electrode 121 is large, so that the above effect is enhanced.
The effect of this embodiment is also enhanced when the first main electrode 121 has a small diameter and the heat capacity is particularly small in order to weld a narrow portion such as a mohawk portion of an automobile.
Here, FIG. 5 is a plane showing a state when the spot welding apparatus 1 according to the present embodiment is applied to the welding of the mohawk portion 5 and the pair of auxiliary electrodes 122 and 122 are brought into contact with the first main electrode 121. FIG. In the welding of the Mohawk section 5, the diameter of the main electrode is limited and the clearance around the main electrode during welding is limited. Therefore, in the past, the measure of simply increasing the diameter of the main electrode could not be taken. According to the embodiment, the contact portions 124, 124 of the auxiliary electrodes 122, 122 can be brought into contact with the first main electrode 121 from the extending direction of the mohawk groove 51, and thus there are restrictions as in the conventional case. Absent.
Moreover, according to this embodiment, since it is the structure which makes the auxiliary electrodes 122 and 122 contact | abut to the 1st main electrode 121, the conventional main electrode can be used continuously as it is. Therefore, the chip dressing of the main electrode does not become difficult as in the case where a member for increasing the heat capacity is attached to the main electrode.

  In addition, according to the resistance welding method using the spot welding apparatus 1 of this embodiment, there exists an effect similar to the said effect.

It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.
For example, in the above embodiment, the pair of auxiliary electrodes 122 and 122 are brought into contact with the workpiece W adjacent to the first main electrode 121, but the present invention is not limited to this. The pair of auxiliary electrodes 122 and 122 may be in contact with the workpiece W adjacent to the second main electrode 131.

  Moreover, in the said embodiment, although the electric current was sent from the 1st main electrode 121 to the direction of the 2nd main electrode 131 and the auxiliary electrodes 122 and 122, you may make the direction through which an electric current flows reverse. That is, the first main electrode 121 may be connected to the negative electrode of the power source, and the second main electrode 131 and the auxiliary electrodes 122 and 122 may be connected to the positive electrode of the power source.

  In the above embodiment, the auxiliary electrodes 122 and 122 are paired, but the present invention is not limited to this. There may be one auxiliary electrode or three or more auxiliary electrodes.

  Further, in the above embodiment, as the heat capacity increasing means, the auxiliary electrode 122 is rotated toward the first main electrode 121 by stopping the rotation shaft 125 by the driving force of the first cylinder mechanism 127, so that the auxiliary electrode 122 is rotated. Although it was made to contact | abut to the 1st main electrode 121, it is not limited to this. For example, the auxiliary electrode 122 may be brought into contact with the first main electrode 121 by sliding the auxiliary electrode 122 with a slide mechanism.

  Moreover, in the said embodiment, although this invention was applied to spot welding, this invention is applicable also to the welding apparatus using the other welding method included in resistance welding, and its method. Further, in the present embodiment, the case where a workpiece (thin plate-thick plate-thick plate) obtained by superimposing three plate materials has been described, but in the present invention, four or more workpieces (for example, thin plate-thin plate-) are used. It is also possible to use a thick plate—a workpiece superposed on a thick plate.

1. Spot welding equipment (resistance welding equipment)
100 ... Control device (energizing means, heat capacity increasing means)
121 ... first main electrode 122 ... auxiliary electrode 124 ... contact portion (heat capacity increasing means)
125 ... Rotating shaft (heat capacity increasing means)
127 ... First cylinder mechanism (heat capacity increasing means)
131 ... 2nd main electrode D1 ... Main current D2 ... Auxiliary current W ... Work W1, W2, W3 ... Plate material

Claims (2)

A resistance welding apparatus for resistance welding a workpiece in which a plurality of plate materials are stacked,
A first main electrode in contact with the workpiece;
A second main electrode that contacts the workpiece from the opposite side of the first main electrode and has a polarity opposite to that of the first main electrode;
An auxiliary electrode which is in contact with the workpiece adjacent to one of the first main electrode and the second main electrode and has a polarity opposite to that of the first main electrode;
While the work is sandwiched and pressurized by the first main electrode, the second main electrode, and the auxiliary electrode, a main current is passed between the first main electrode and the second main electrode, and the first Energizing means for supplying an auxiliary current between the main electrode and the auxiliary electrode;
And a heat capacity increasing means for increasing the heat capacity of the main electrode by bringing the auxiliary electrode into contact with the adjacent main electrode after the auxiliary current is cut off. A resistance welding method for resistance welding a workpiece in which a plurality of plate materials are stacked,
Bringing the first main electrode into contact with the workpiece;
A second main electrode having a polarity opposite to that of the first main electrode is brought into contact with the workpiece from a side opposite to the first main electrode;
An auxiliary electrode having a polarity opposite to that of the first main electrode is brought into contact with the workpiece adjacent to one of the first main electrode and the second main electrode; and
Sandwiching and pressurizing the workpiece with the first main electrode, the second main electrode, and the auxiliary electrode;
An energization step of flowing a main current between the first main electrode and the second main electrode and flowing an auxiliary current between the first main electrode and the auxiliary electrode;
A resistance welding method comprising: a heat capacity increasing step of increasing a heat capacity of the main electrode by bringing the auxiliary electrode into contact with the adjacent main electrode after cutting off the auxiliary current.

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