JP2020142251A - Resistance spot welding device and resistance spot welding method - Google Patents

Abstract

To provide a resistance spot welding device and a resistance spot welding method capable of performing resistance spot welding of sheet assembly of which at least one sheet of steel plate has a galvanized layer of a plurality of steel plates which are superimposed, without welding defect.SOLUTION: A resistance spot welding device includes one assembly of electrodes 50, 60 which are arranged opposite to each other so as to hold a plate assembly 20 there between and can move so as to approach or space to each other. Therein, one assembly of the electrodes 50, 60 respectively have main electrodes 51, 61, at the same time, one side of electrode 50 has an auxiliary electrode 52 arranged on the neighborhood of the main electrode 51 and movable independent of the main electrode 51. The resistance spot welding device includes an electric power source 70 respectively conductible between the main electrode 51 and the auxiliary electrode 52, and between one assembly of main electrodes 51, 61, and further includes switches 75, 76. 77 capable of switching to either one side of conduction between the main electrode 51 and the auxiliary electrode 52 or conduction between one assembly of main electrodes 51, 61.SELECTED DRAWING: Figure 1

Description

The present invention relates to a resistance spot welding apparatus and a resistance spot welding method. More specifically, a plate set containing at least one steel plate having a zinc-based plating layer is welded in a good state without grain boundary brittle cracking. The present invention relates to a resistance spot welding apparatus and a resistance spot welding method capable of performing.

In recent years, in the automobile field, in order to reduce fuel consumption, reduce CO ₂ emissions, reduce the weight of the vehicle body, and improve collision safety, it has been required to increase the strength of the vehicle body member, such as the body member and various parts. Ultra high-tensile steel sheet is used for. Further, from the viewpoint of high rust prevention of the vehicle body, a zinc-based plated steel sheet obtained by subjecting an ultra-high-tensile steel sheet to a zinc-based plating treatment is used, and the vehicle body is assembled and parts are attached by resistance spot welding.

However, the ultra-high-tensile steel sheet has a problem of inferior weldability. In particular, the zinc-plated ultra-high-tensile steel sheet is subject to electrode pressure and tensile stress due to thermal expansion and contraction of the steel sheet at the welded part during resistance spot welding. In addition, zinc melted on the surface of the steel sheet at the welded portion and an alloy of zinc and copper at the electrode invade the grain boundaries of the steel sheet to reduce the grain boundary strength, called grain boundaries called LME (Liquid Metal Embryment). It is known that brittle cracking is likely to occur. The biggest cause of LME cracking is an increase in the alloy component amount (C, Si) of the steel sheet.

Therefore, the steel sheet manufacturing means for increasing the steel sheet strength while lowering the value of the alloy component amount is the most effective, but it is actually quite difficult. Therefore, suppression of LME cracking is desired from the aspect of welding technology, and various suppression methods have been studied by steel makers for many years.

Here, in Patent Document 1, the post-weld holding time Ht (seconds) from the end of welding energization between the weld electrodes to the non-contact between the weld electrodes and the member to be welded is lengthened to completely complete the welded portion. A spot welding method in which LME cracking is suppressed and joint strength is improved by waiting until it hardens is disclosed.

Japanese Patent No. 6108017

However, according to the technique of Patent Document 1, there is a problem that the welding efficiency is lowered because the holding time after energization is long. Further, if zinc is welded while being present in the welded portion, it is difficult to completely prevent LME cracking caused by zinc. Therefore, if zinc in the welded portion can be physically removed before welding, LME cracking will not occur in principle. As a partial zinc removal method, there are a mechanical grinding method such as a grinder and a method of evaporating and removing with a laser or a plasma arc, but it requires equipment introduction and human labor as a pre-welding process, which is extremely large. It will increase the cost.

Further, if zinc is removed at the component stage, it is necessary to assemble the zinc-removed portion (that is, the planned welding location) together at the time of welding, which is not realistic for the automobile industry application. Further, if the zinc-removed portion is large with respect to the planned welding portion, there is a problem that the rust preventive function of the portion is impaired. Therefore, there is a demand for a method of automatically removing zinc only at a planned welding site in a short time in almost the same process as welding.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to form a plate assembly in which at least one steel plate has a zinc-based plating layer among a plurality of superposed steel plates without welding defects. It is an object of the present invention to provide a resistance spot welding apparatus and a resistance spot welding method capable of welding.

Therefore, the above object of the present invention is achieved by the configuration of the following (1) relating to the resistance spot welding apparatus.
(1) A resistance spot welding apparatus for performing resistance spot welding on a plate set in which at least one of a plurality of stacked steel plates has a zinc-based plating layer.
It is provided with a set of electrodes that are arranged so as to sandwich the plate assembly and can be moved so as to approach or separate from each other.
Each of the pair of electrodes has a main electrode and
At least one of the pair of electrodes has an auxiliary electrode that is located in the vicinity of the main electrode and can move independently of the main electrode.
A power source capable of energizing between the main electrode and the auxiliary electrodes arranged in the vicinity thereof and between a set of the main electrodes is provided.
A resistance spot welding apparatus further comprising a control unit capable of switching between energization between the main electrode and the auxiliary electrodes arranged in the vicinity thereof, or energization between a set of the main electrodes.

Further, preferred embodiments of the present invention relating to the resistance spot welding apparatus relate to the following (2) to (5).
(2) The resistance spot welding apparatus according to (1), wherein the auxiliary electrode is formed in a ring shape so as to surround the main electrode arranged in the vicinity thereof.
(3) The resistor according to (1) or (2), wherein each electric path between the power source and the main electrode or the auxiliary electrode is provided with a switch for connecting or disconnecting the respective electric paths. Spot welding equipment.
(4) The resistance spot welding apparatus according to any one of (1) to (3), wherein the power source is one.
(5) The plate assembly has a zinc-based plating layer on at least one of the outermost layers and does not have a zinc-based plating layer on the intermediate layer (including the case where the intermediate layer is not provided), (1). The resistance spot welding apparatus according to any one of (4).

Further, the above object of the present invention is achieved by the configuration of the following (6) according to the resistance spot welding method.
(6) A resistance spot welding method in which resistance spot welding is performed on a plate set in which at least one of a plurality of stacked steel plates has a zinc-based plating layer.
Between a set of electrodes that are arranged to face each other and each have a main electrode, at least one of which is placed in the vicinity of the main electrode and has an auxiliary electrode that can move independently of the main electrode. The process of arranging the board and
A step of partially removing the zinc-based plating layer by energizing between the main electrode and the auxiliary electrode arranged in the vicinity thereof, and
A step of joining the plate assembly by resistance spot welding by energizing between the pair of main electrodes while pressurizing the plate assembly.
A resistance spot welding method.

Further, preferred embodiments of the present invention relating to the resistance spot welding method relate to the following (7) to (10).
(7) The resistance spot welding method according to (6), wherein the step of partially removing the zinc-based plating layer is performed in a state where the electrode on the non-energized side is in contact with the plate assembly. ..
(8) The resistance spot welding method according to (6) or (7), wherein each of the auxiliary electrodes is formed in a ring shape so as to surround the main electrode arranged in the vicinity thereof.
(9) The energization performed between the main electrode and the auxiliary electrodes arranged in the vicinity thereof, or between the set of main electrodes is between one power source and the main electrode or the auxiliary electrode. The resistance spot welding method according to any one of (6) to (8), which is performed by switching a switch for connecting or disconnecting each electric path.
(10) The plate assembly has a zinc-based plating layer on at least one of the outermost layers and does not have a zinc-based plating layer on the intermediate layer (including the case where the intermediate layer is not provided), (6). The resistance spot welding method according to any one of (9).

Further, the above object of the present invention is achieved by the following configuration (11) relating to the resistance spot welding apparatus.
(11) A resistance spot welding apparatus for performing resistance spot welding on a plate set in which at least one of a plurality of stacked steel plates has a zinc-based plating layer.
It is provided with a first composite electrode and a second composite electrode which are arranged so as to sandwich the plate assembly and can be moved so as to approach or separate from each other.
The first composite electrode has a first welding electrode and a first auxiliary electrode that is arranged in the vicinity of the first welding electrode and can move independently of the first welding electrode.
The second composite electrode has a second weld electrode and a second auxiliary electrode that is arranged in the vicinity of the second weld electrode and can move independently of the second weld electrode.
Energization is possible between the first welding electrode and the first auxiliary electrode, between the second welding electrode and the second auxiliary electrode, and between the first welding electrode and the second welding electrode. A resistance spot welding device equipped with an additional power source.

Further, preferred embodiments of the present invention relating to the resistance spot welding apparatus relate to the following (12) to (16).
(12) Energization between the first welding electrode and the first auxiliary electrode, energization between the second welding electrode and the second auxiliary electrode, or between the first welding electrode and the second welding electrode. The resistance spot welding apparatus according to (11), further comprising a control unit capable of switching between energization and energization.
(13) The first auxiliary electrode and the second auxiliary electrode are formed in a ring shape so as to surround the first welding electrode and the second welding electrode, respectively, according to (11) or (12). Resistance spot welding equipment.
(14) A switch that connects or cuts off each electric path to each electric path between the power source and the first welding electrode, the first auxiliary electrode, the second welding electrode, or the second auxiliary electrode. The resistance spot welding apparatus according to any one of (11) to (13), respectively.
(15) The resistance spot welding apparatus according to any one of (11) to (14), wherein the power source is one.
(16) The plate assembly has a zinc-based plating layer on at least one of the outermost layers and does not have a zinc-based plating layer on the intermediate layer (including the case where the intermediate layer is not provided), (11). The resistance spot welding apparatus according to any one of (15).

Further, the above object of the present invention is achieved by the configuration of the following (17) according to the resistance spot welding method.
(17) A resistance spot welding method in which resistance spot welding is performed on a plate assembly in which at least one of a plurality of stacked steel plates has a zinc-based plating layer.
A first composite electrode having a first auxiliary electrode which is arranged to face each other and is arranged in the vicinity of the first welding electrode and the first welding electrode and can move independently of the first welding electrode, and a second welding electrode. And the step of arranging the plate assembly between the second welding electrode and the second composite electrode having the second auxiliary electrode that can move independently from the second welding electrode.
The zinc-based plating layer is partially removed by energizing at least one between the first welding electrode and the first auxiliary electrode and between the second welding electrode and the second auxiliary electrode. Process and
A step of joining the plate assembly by resistance spot welding by energizing between the first welding electrode and the second welding electrode while pressurizing the plate assembly.
A resistance spot welding method.

Further, preferred embodiments of the present invention relating to the resistance spot welding method relate to the following (18) to (22).
(18) In the step of partially removing the zinc-based plating layer, the first welding electrode and the first auxiliary electrode, or the second welding electrode and the second auxiliary electrode on the non-energized side are removed. The resistance spot welding method according to (17), which is performed in a state of being in contact with the plate assembly.
(19) When both the outermost steel sheets in the plate assembly have a zinc-based plating layer,
The resistance spot welding method according to (17) or (18), wherein energization is not performed simultaneously between the first welding electrode and the first auxiliary electrode, and between the second welding electrode and the second auxiliary electrode. ..
(20) As the first auxiliary electrode and the second auxiliary electrode, those formed in a ring shape so as to surround the first welding electrode and the second welding electrode are used, respectively, (17) to (19). ). The resistance spot welding method according to any one of.
(21) It is performed between the first welding electrode and the first auxiliary electrode, between the second welding electrode and the second auxiliary electrode, or between the first welding electrode and the second welding electrode. Energization is performed by switching a switch that connects or cuts off each electric path between one power source and the first welding electrode, the first auxiliary electrode, the second welding electrode, or the second auxiliary electrode. The resistance spot welding method according to any one of (17) to (20).
(22) The plate assembly has a zinc-based plating layer on at least one of the outermost layers and does not have a zinc-based plating layer on the intermediate layer (including the case where the intermediate layer is not provided), (17). , (18), (20) or (21). The resistance spot welding method according to any one of (18), (20) and (21).

According to the resistance spot welding apparatus and the resistance spot welding method of the present invention, they are arranged so as to face each other and each has a main electrode, and at least one of them is arranged in the vicinity of the main electrode and is independent of the main electrode. A plate set in which at least one steel plate has a zinc-based plating layer is arranged between a set of electrodes having a movable auxiliary electrode, and a zinc-based plating layer is applied by energizing between the main electrode and the auxiliary electrode. Is partially removed, and then electricity is applied between one set of main electrodes while pressurizing the plate assembly. Therefore, a plate assembly in which at least one steel plate has a zinc-based plating layer is spot-welded without welding defects. can do.

FIG. 1 is a perspective view showing a schematic configuration of a resistance spot welding apparatus according to a first embodiment of the present invention. FIG. 2 is a diagram showing a procedure of resistance spot welding of a plate set composed of a zinc-based plated steel plate and a steel plate having no zinc-based plating layer by the resistance spot welding apparatus shown in FIG. FIG. 3 is a perspective view showing a schematic configuration of a resistance spot welding apparatus when the shape of the auxiliary electrode is intermittently formed in the circumferential direction. FIG. 4 is a perspective view showing a schematic configuration of a resistance spot welding apparatus according to a second embodiment of the present invention. FIG. 5 is a diagram showing a procedure of resistance spot welding of a plate set in which two galvanized steel sheets are laminated by the resistance spot welding apparatus shown in FIG. FIG. 6 shows a procedure in which a steel plate having no zinc-based plating layer performs resistance spot welding of a plate set consisting of three steel plates sandwiched between two galvanized steel plates by the resistance spot welding apparatus shown in FIG. It is a figure which shows.

Hereinafter, each resistance spot welding apparatus according to the present invention and each embodiment of the resistance spot welding method using the resistance spot welding apparatus will be described in detail with reference to the drawings.

<First Embodiment>
(Resistance spot welding equipment)
FIG. 1 is a schematic configuration diagram of a resistance spot welding apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the resistance spot welding apparatus 10 according to the present embodiment does not have a steel plate 30 having a zinc-based plating layer 31 on its surface (hereinafter, also referred to as a zinc-based plating steel sheet 30) and a zinc-based plating layer. This is a welding device for joining a plate set 20 composed of a plurality of steel plates 30 and 40 on which steel plates 40 are laminated by resistance spot welding.

Examples of the galvanized steel sheet 30 include alloyed hot-dip galvanized steel sheets (GA), hot-dip galvanized steel sheets (GI), and electrogalvanized steel sheets (EG). The tensile strength (TS) of the galvanized steel sheet 30 is not particularly limited, but is, for example, a high-strength steel sheet (High Tensile Steel Steel: HTSS) of 980 MPa or more, preferably 1180 MPa or more.

The resistance spot welding device 10 is provided with a set of electrodes 50, 60 which are arranged so as to sandwich the plate assembly 20 so as to face each other in the vertical direction in the drawing and can be moved so as to approach or separate from each other. One electrode 50 (hereinafter, also referred to as the first composite electrode 50) is a composite electrode, and is arranged so as to surround the main electrode 51 (hereinafter, also referred to as the first welding electrode 51) and the periphery of the main electrode 51. A ring-shaped auxiliary electrode 52 is provided. The main electrode 51 and the auxiliary electrode 52 are driven by a known driving device (not shown) such as an air type or an electric type (servo type), and independently approach the plate assembly 20 in the vertical direction in the drawing. Or it can move in the direction of separation. In this embodiment, the electrode 50 is arranged on the zinc-based plated steel sheet 30 side of the plate assembly 20.

The other electrode 60 is not provided with an auxiliary electrode and is composed of only a main electrode 61 (hereinafter, also referred to as a second welding electrode 61), and like the one electrode 50, a known driving device such as an air type or an electric type. It is driven by (not shown) and can move in the vertical direction in the figure, that is, in the direction of approaching or separating from the plate set 20. The electrode 50 and the electrode 60 can move independently of each other. In the present embodiment, the electrode 60 is arranged on the steel plate 40 side of the plate assembly 20 which does not have the zinc-based plating layer.

The main electrode 51 and the main electrode 61 can press the plate assembly 20 with a relatively strong pressing force required for performing resistance spot welding. Further, the auxiliary electrode 52 only needs to be in contact with the galvanized steel sheet 30 to the extent that it can be energized with the main electrode 51, and does not require as much force as the pressing force of the main electrodes 51 and 61.

Further, the resistance spot welding device 10 includes one power supply 70. The power source 70 is connected to the main electrode 51 by an electric path 71 and is connected to an auxiliary electrode 52 by an electric path 72. A switch 75, which is a control unit for connecting or disconnecting the electric path 71, is provided in the middle of the electric path 71, and a switch 76, which is a control unit for connecting or disconnecting the electric path 72, is provided in the middle of the electric path 72. Has been done. The power supply 70 is also connected to the main electrode 61 by an electric path 73. A switch 77, which is a control unit for connecting or disconnecting the electric path 73, is provided in the middle of the electric path 73.

As a result, by appropriately connecting or disconnecting the switches 75, 76, 77, energization between the main electrode 51 and the auxiliary electrodes 52 arranged in the vicinity thereof, or between a set of main electrodes 51, 61 It can be switched to either energization.

As shown in FIG. 1, the power supply 70 is composed of one power supply, but is composed of a plurality of power supplies, for example, an individual power supply is installed for each of the main electrodes 51 and 61 and the auxiliary electrode 52. You may. Further, the power source may be an AC power source or a DC power source, and a known general power source used for resistance spot welding can be used.

(Resistance spot welding method)
Next, a method of resistance spot welding of the plate assembly 20 of the zinc-based plated steel sheet 30 and the steel plate 40 having no zinc-based plating layer using the resistance spot welding apparatus 10 will be described in detail with reference to FIG.

As shown in FIG. 2, in the resistance spot welding method according to the present embodiment, first, a zinc-based plated steel sheet 30 and a steel sheet having no zinc-based plated layer are provided between a set of electrodes 50 and 60 separated from each other. A plate set 20 composed of 40 is arranged. At that time, the electrode 50, that is, the main electrode 51 and the auxiliary electrode 52 are arranged on the zinc-based plated steel sheet 30 side, and the electrode 60, that is, the main electrode 61 is arranged on the steel plate 40 side that does not have the zinc-based plated layer ( Step1).

Next, a drive device (not shown) is operated to move the electrodes 50 (main electrode 51, auxiliary electrode 52) toward the plate assembly 20, and the main electrode 51 and the auxiliary electrode 52 are brought into contact with the galvanized steel sheet 30. Then, the switches 75 and 76 are closed, and electricity is applied between the main electrode 51 and the auxiliary electrode 52 via the galvanized steel sheet 30. As a result, a current radiates from the main electrode 51 toward the auxiliary electrode 52 or in the opposite direction in the in-plane direction of the galvanized steel sheet 30, and a heating region 32 is formed in the galvanized steel sheet 30. Is done (Step 2).

By heating the region between the main electrode 51 and the auxiliary electrode 52, the zinc-based plating layer 31 having a low melting point in the galvanized steel sheet 30 is evaporated and removed, and the raw steel sheet without the zinc-based plating layer 31 is removed. The exposed exposed region 33 is formed on the upper and lower surfaces of the galvanized steel sheet 30 (Step 3).

The zinc gas evaporated by heat is directly discharged to the outside from the upper surface of the galvanized steel sheet 30. Further, the zinc gas evaporated from the lower surface of the galvanized steel sheet 30 in contact with the steel sheet 40 is discharged to the outside through the gap between the galvanized steel sheet 30 and the steel sheet 40. In order to properly secure the gap and smoothly discharge the zinc gas, it is desirable not to excessively press the zinc-based plated steel sheet 30 and the steel sheet 40 in the above-mentioned removal step of the zinc-based plated layer 31.

Further, the shape of the auxiliary electrode 52 is not limited to the ring shape, but by forming the auxiliary electrode 52 into a ring shape (see FIG. 1), the heating region 32 and the exposed region 33 also become circular, and an ideal evaporation state of zinc is created. Therefore, the zinc-based plating layer 31 can be removed in a shape suitable for the subsequent resistance spot welding.

The shape of the auxiliary electrode 52 is not limited to the one formed in a ring shape continuously in the circumferential direction. For example, as shown in FIG. 3, at least a part of the auxiliary electrode 52 in the longitudinal direction is the auxiliary electrode 52. It may be formed intermittently (discontinuously) in the circumferential direction of the above (note that the power supply, the electric path, and the switch are not shown in FIG. 3). By forming the auxiliary electrode 52 intermittently in this way, the portion where the auxiliary electrode 52 contacts the steel plates 30 and 40 can be made smaller, so that at least one of the steel plates 30 and 40 as shown in FIG. , It can be suitably used for welding when the planned welding location becomes narrow due to processing such as press forming.

Next, the drive device is operated to move the main electrode 51 of the electrode 50 and the main electrode 61 of the electrode 60 toward the plate assembly 20, respectively, and the plate assembly 20 is strongly sandwiched between the main electrodes 51 and 61. The switches 75 and 77 are closed while applying a predetermined pressing force, and electricity is applied between the main electrodes 51 and 61 via the galvanized steel plate 30 and the steel plate 40. As a result, the plate assembly 20 is cooled after the nugget 34, which is a weld metal portion, is formed between the galvanized steel sheet 30 and the steel sheet 40 (Step 4).

After that, resistance spot welding between the galvanized steel sheet 30 and the steel sheet 40 is completed by separating the electrodes 50 and 60 from the plate assembly 20 (Step 5).

The step of partially removing the zinc-based plating layer 31 may be performed in a state where the electrode 60 on the non-energized side is in contact with the plate assembly 20. When the zinc-based plating layer 31 is removed in this way, the electrode 60 is brought into contact with the plate assembly 20 to be in a standby state, so that the subsequent step of resistance spot welding of the plate assembly 20 can be performed immediately. Welding efficiency is improved. At that time, the main electrode 51 in contact with the zinc-based plated steel sheet 30 does not need to be separated from the plate assembly 20 after the step of removing the zinc-based plated layer 31.

Further, in the step of resistance spot welding of the plate assembly 20, it is not always necessary to separate the auxiliary electrodes 52, but by retracting the auxiliary electrodes 52, dust that is inevitably generated (that is, between the electrodes and the steel plate) is generated. Sputter) is accumulated in the gap between the main electrode 51 and the auxiliary electrode 52, and it is possible to prevent troubles such as the main electrode 51 and the auxiliary electrode 52 being constantly energized.

As described above, according to the resistance spot welding apparatus 10 of the present embodiment, only the zinc-based plating layer 31 at the planned welding portion of the zinc-based plated steel plate 30 is removed by evaporation of zinc to form the exposed region 33. Since the exposed region 33 and the steel plate 40 having no zinc-based plating layer are spot-welded by resistance spot welding, the influence of zinc is eliminated, grain boundary brittle cracks (LME cracks) are prevented, and there are no welding defects. Welding can be performed in the state.

Further, in the range where the zinc-based plating layer 31 is removed (exposed area 33), only the inside of the ring-shaped auxiliary electrode 52, that is, the welded portion (that is, the planned welding portion) is removed with high positional accuracy, which is unnecessary. Since the zinc-based plating layer 31 in a wide range is not removed, the rust preventive effect is not impaired, and the zinc-based plating layer 31 can be removed in a short time in substantially the same process as welding.

<Second Embodiment>
(Resistance spot welding equipment)
Subsequently, the resistance spot welding apparatus according to the second embodiment will be described. FIG. 4 is a schematic configuration diagram of a resistance spot welding apparatus according to a second embodiment of the present invention. As shown in FIG. 4, in the resistance spot welding apparatus 10A according to the present embodiment, a plurality of zinc-based plated steel sheets 30A and 30B having a zinc-based plating layer 31 on the surface (two in the embodiment shown in the figure) are superposed. The plate assembly 20 is joined by resistance spot welding.

The resistance spot welding device 10A includes a first composite electrode 50 and a second composite electrode 60, which are arranged so as to sandwich the plate assembly 20 so as to face each other in the vertical direction in the drawing and can move so as to approach or separate from each other. .. The first composite electrode 50 and the second composite electrode 60 are the main electrode (first weld electrode) 51 and the main electrode (second weld electrode) 61, respectively, and the periphery of the first weld electrode 51 and the second weld electrode 61. A ring-shaped first auxiliary electrode 52 and a second auxiliary electrode 62 are provided so as to surround the two auxiliary electrodes.

The first welding electrode 51, the second welding electrode 61, the first auxiliary electrode 52, and the second auxiliary electrode 62 are driven by a known driving device such as an air type or an electric type, and are independently moved up and down in the drawing. It is movable in a direction, that is, in a direction that approaches or separates from the plate assembly 20.

The first welding electrode 51 and the second welding electrode 61 can press the plate assembly 20 with a relatively strong pressing force required for performing resistance spot welding. Further, the first auxiliary electrode 52 and the second auxiliary electrode 62 may be in contact with the zinc-based plated steel plate 30 to such an extent that they can be energized between the first welding electrode 51 and the second welding electrode 61, respectively. It does not require as much force as the pressing force of the welding electrode 51 and the second welding electrode 61.

Further, the resistance spot welding device 10A includes one power supply 70. The power source 70 is connected to the first welding electrode 51 by an electric path 71 and is connected to the first auxiliary electrode 52 by an electric path 72. A switch 75, which is a control unit for connecting or disconnecting the electric path 71, is provided in the middle of the electric path 71, and a switch 76, which is a control unit for connecting or disconnecting the electric path 72, is provided in the middle of the electric path 72. Has been done. Further, the power source 70 is connected to the second welding electrode 61 by the electric path 73, and is connected to the second auxiliary electrode 62 by the electric path 74. A switch 77, which is a control unit for connecting or disconnecting the electric path 73, is provided in the middle of the electric path 73, and a switch 78, which is a control unit for connecting or disconnecting the electric path 74, is provided in the middle of the electric path 74. Has been done.

As a result, by appropriately connecting or disconnecting the switches 75, 76, 77, 78, between the first welding electrode 51 and the first auxiliary electrode 52, between the second welding electrode 61 and the second auxiliary electrode 62, and It is possible to energize or shut off between the first welding electrode 51 and the second welding electrode 61, respectively.

As shown in FIG. 4, the power supply 70 is composed of one power supply, but may be composed of a plurality of power supplies as in the first embodiment. Further, the power source may be an AC power source or a DC power source, and a known general power source used for resistance spot welding can be used.

(Resistance spot welding method)
Next, a method of resistance spot welding of a plate set 20 composed of a plurality of galvanized steel sheets 30 using the resistance spot welding apparatus 10A will be described in detail with reference to FIG.

As shown in FIG. 5, in the resistance spot welding method according to the present embodiment, first, a plurality of resistance spot welding methods are used between the first composite electrode 50 and the second composite electrode 60 in a state of being separated from each other (two in the embodiment shown in the figure). ), The zinc-based plated steel plates 30A and 30B are arranged (Step 1).

Next, a drive device (not shown) is operated to move the first composite electrode 50 (first welding electrode 51, first auxiliary electrode 52) toward the plate assembly 20, and the first welding electrode 51 and the first auxiliary electrode 52 are moved. Is brought into contact with the zinc-based plated steel sheet 30A arranged on the upper side. Then, the switches 75 and 76 are closed, and electricity is applied between the first welding electrode 51 and the first auxiliary electrode 52 via the galvanized steel sheet 30A. As a result, a current radiates from the first welding electrode 51 toward the first auxiliary electrode 52 or in the opposite direction in the in-plane direction of the galvanized steel sheet 30A, and flows to the upper galvanized steel sheet 30A. The heating region 32 is formed (Step 2).

By heating the region between the first welding electrode 51 and the first auxiliary electrode 52, the zinc-based plating layer 31 having a low melting point in the galvanized steel sheet 30A is evaporated and removed, and there is no zinc-based plating layer 31. The exposed region 33 where the raw steel sheet is exposed is formed on the upper and lower surfaces of the galvanized steel sheet 30A (Step 3).

Next, the first composite electrode 50 is separated from the galvanized steel sheet 30A, and the second composite electrode 60 (second welding electrode 61, second auxiliary electrode 62) arranged below the galvanized steel sheet 30B is assembled into a plate 20. The second welding electrode 61 and the second auxiliary electrode 62 are brought into contact with the galvanized steel sheet 30B arranged on the lower side. Then, the switches 77 and 78 are closed, and electricity is applied between the second welding electrode 61 and the second auxiliary electrode 62 via the galvanized steel sheet 30B. As a result, currents flow radially from the second welding electrode 61 toward the second auxiliary electrode 62 or in the opposite direction in the in-plane direction of the galvanized steel sheet 30B, and the lower galvanized steel sheet 30B A heating region 32 is also formed in (Step 4).

By heating the region between the second welding electrode 61 and the second auxiliary electrode 62, the zinc-based plating layer 31 having a low melting point in the galvanized steel sheet 30B is evaporated and removed, and there is no zinc-based plating layer 31. The exposed region 33 where the raw steel sheet is exposed is also formed on the upper and lower surfaces of the galvanized steel sheet 30B (Step 5).

As a result, the zinc-based plating layer 31 at the planned welding location of the zinc-based plated steel sheets 30A and 30B is completely removed.

Subsequently, the drive device is operated to move the first welding electrode 51 of the first composite electrode 50 and the second welding electrode 61 of the second composite electrode 60 toward the plate assembly 20, respectively, and the first welding electrode. The plate set 20 is strongly sandwiched between the 51 and the second welding electrode 61, the switches 75 and 77 are closed while applying a predetermined pressing force, and the first welding electrode 51 and the first welding electrode 51 and the first welding electrode 51 and the first welding electrode 51 and the first welding electrode 51 and the first welding electrode 51 and the 1st welding electrode 51 and the 2 2 Energize between the welding electrodes 61. As a result, the plate assembly 20 is cooled after the nugget 34, which is a weld metal portion, is formed between the galvanized steel sheets 30A and 30B (Step 6).

After that, the resistance spot welding of the galvanized steel sheets 30A and 30B is completed by separating the first welding electrode 51 and the second welding electrode 61 from the plate assembly 20 (Step 7).

As described above, a pair of the first composite electrode 50 and the second composite electrode 60 are arranged above and below the plate assembly 20, and the zinc-based plating layers of the zinc-based plated steel plates 30A and 30B are arranged prior to the welding of the plate assembly 20. Since 31 is removed in a separate step, energization between the zinc-based plated steel plates 30A and 30B in the evaporation removal step of the zinc-based plating layer 31 is prevented. As a result, the uneven temperature rise is suppressed, the evaporation of zinc is not unstable, and the zinc-based plating layer 31 can be stably removed.

As described above, according to the resistance spot welding apparatus 10A of the present embodiment, only the zinc-based plating layers 31 at the planned welding points of the zinc-based plated steel plates 30A and 30B arranged above and below are removed by evaporation of zinc. After forming the exposed region 33, resistance spot welding is performed between the exposed regions 33, so that the influence of zinc is eliminated, grain boundary brittle cracking (LME cracking) is prevented, and welding is performed in a good condition without welding defects. It can be performed.

Further, the range from which the zinc-based plating layer 31 is removed (exposed area 33) is unnecessary because only the inside of the ring-shaped first auxiliary electrode 52 and the second auxiliary electrode 62, that is, the welded portion is removed with high positional accuracy. Since the zinc-based plating layer 31 in a wide range is not removed, the rust preventive effect is not impaired, and the zinc-based plating layer 31 can be removed in a short time in substantially the same process as welding.

(Variation example of resistance spot welding method)
In the above description, an example in which the plate set 20 is composed of two steel plates (a galvanized steel plate 30 and a steel plate 40 having no galvanized plating layer, or two galvanized steel plates 30A and 30B) has been described. However, the plate set 20 may be composed of three or more steel plates.

FIG. 6 is a diagram showing a procedure for resistance spot welding of a plate set 20 composed of three steel plates. As shown in FIG. 6, the plate assembly 20 has a structure in which both sides of a steel plate 40 having no zinc-based plating layer are sandwiched between two zinc-based plated steel plates 30A and 30B. It is preferable to arrange the steel plate 40 having no zinc-based plating layer in the intermediate portion in order to realize good welding without LME cracking. The number of steel plates 40 having no zinc-based plating layer arranged in the intermediate portion may be one, but may be two or more as long as the plate assembly 20 can be welded.

Welding of the plate assembly 20 composed of three steel plates 30A, 40, and 30B can also be performed by the resistance spot welding apparatus 10A described in the second embodiment.

Specifically, first, a plate set 20 composed of three steel plates 30A, 40, and 30B is arranged between the first composite electrode 50 and the second composite electrode 60 in a state of being separated from each other (Step 1).

Next, a drive device (not shown) is operated to move the first composite electrode 50 (first welding electrode 51, first auxiliary electrode 52) toward the plate assembly 20, and the first welding electrode 51 and the first auxiliary electrode 52 are moved. Is brought into contact with the zinc-based plated steel sheet 30A arranged on the upper side. Then, the switches 75 and 76 are closed, and electricity is applied between the first welding electrode 51 and the first auxiliary electrode 52 via the galvanized steel sheet 30A. As a result, a current radiates from the first welding electrode 51 toward the first auxiliary electrode 52 or in the opposite direction in the in-plane direction of the galvanized steel sheet 30A, and flows to the upper galvanized steel sheet 30A. The heating region 32 is formed (Step 2).

By heating the region between the first welding electrode 51 and the first auxiliary electrode 52, the zinc-based plating layer 31 having a low melting point in the galvanized steel sheet 30A is evaporated and removed, and there is no zinc-based plating layer 31. The exposed region 33 where the raw steel sheet is exposed is formed on the upper and lower surfaces of the galvanized steel sheet 30A (Step 3).

Next, the first composite electrode 50 is separated from the galvanized steel sheet 30A, and the second composite electrode 60 (second welding electrode 61, second auxiliary electrode 62) arranged below the galvanized steel sheet 30B is assembled into a plate 20. The second welding electrode 61 and the second auxiliary electrode 62 are brought into contact with the galvanized steel sheet 30B arranged on the lower side. Then, the switches 77 and 78 are closed, and electricity is applied between the second welding electrode 61 and the second auxiliary electrode 62 via the galvanized steel sheet 30B. As a result, currents flow radially from the second welding electrode 61 toward the second auxiliary electrode 62 or in the opposite direction in the in-plane direction of the galvanized steel sheet 30B, and the lower galvanized steel sheet 30B A heating region 32 is also formed in (Step 4).

By heating the region between the second welding electrode 61 and the second auxiliary electrode 62, the zinc-based plating layer 31 having a low melting point in the galvanized steel sheet 30B is evaporated and removed, and there is no zinc-based plating layer 31. The exposed region 33 where the raw steel sheet is exposed is also formed on the upper and lower surfaces of the galvanized steel sheet 30B (Step 5).

As a result, the zinc-based plating layer 31 at the planned welding location of the zinc-based plated steel sheets 30A and 30B is completely removed.

Subsequently, the drive device is operated to move the first welding electrode 51 of the first composite electrode 50 and the second welding electrode 61 of the second composite electrode 60 toward the plate assembly 20, respectively, and the first welding electrode. The plate assembly 20 is strongly sandwiched between the 51 and the second welding electrode 61, the switches 75 and 77 are closed while applying a predetermined pressing force, and the first welding electrode 51 is passed through the three steel plates 30A, 40 and 30B. And energize between the second welding electrodes 61. As a result, the plate assembly 20 is cooled after the nugget 34, which is a weld metal portion, is formed between the three steel plates 30A, 40, and 30B (Step 6).

After that, the resistance spot welding of the three steel plates 30A, 40, and 30B is completed by separating the first welding electrode 51 and the second welding electrode 61 from the plate assembly 20 (Step 7).

Other configurations and operations are the same as those of the resistance spot welding apparatus 10A of the second embodiment.

The present invention is not limited to the above-described embodiment, and can be appropriately modified, improved, and the like.

As described above, the following matters are disclosed in this specification.
(1) A resistance spot welding apparatus for performing resistance spot welding on a plate set in which at least one of a plurality of stacked steel plates has a zinc-based plating layer.
It is provided with a set of electrodes that are arranged so as to sandwich the plate assembly and can be moved so as to approach or separate from each other.
Each of the pair of electrodes has a main electrode and
At least one of the pair of electrodes has an auxiliary electrode that is located in the vicinity of the main electrode and can move independently of the main electrode.
A power source capable of energizing between the main electrode and the auxiliary electrodes arranged in the vicinity thereof and between a set of the main electrodes is provided.
A resistance spot welding apparatus further comprising a control unit capable of switching between energization between the main electrode and the auxiliary electrodes arranged in the vicinity thereof, or energization between a set of the main electrodes.

According to this configuration, at least one steel plate is a zinc-based plating layer between a set of electrodes of the main electrode and another main electrode and an electrode having an auxiliary electrode arranged in the vicinity of the main electrode. After arranging the plate assembly with the above and energizing between the main electrode and the auxiliary electrode to partially remove the zinc-based plating layer, energizing between one set of main electrodes while pressurizing the plate assembly. Since the plate assembly is resistance spot welded, it is possible to perform resistance spot welding of a plate assembly in which at least one of the plurality of steel plates has a zinc-based plating layer without welding defects.

(2) The resistance spot welding apparatus according to (1), wherein the auxiliary electrode is formed in a ring shape so as to surround the main electrode arranged in the vicinity thereof.
According to this configuration, the heating region and the exposed region are also circular, and an ideal evaporation state of zinc can be created. Therefore, the zinc-based plating layer can be removed in a shape suitable for the subsequent resistance spot welding. .. In addition, the zinc-based plating layer can be removed only in the vicinity of the resistance spot welded range, and the deterioration of the anticorrosion effect can be suppressed.

(3) The resistor according to (1) or (2), wherein each electric path between the power source and the main electrode or the auxiliary electrode is provided with a switch for connecting or disconnecting the respective electric paths. Spot welding equipment.
According to this configuration, by switching the switch, it is possible to easily remove the zinc-based plating layer from the zinc-based plated steel sheet and perform resistance spot welding of the plate assembly.

(4) The resistance spot welding apparatus according to any one of (1) to (3), wherein the power source is one.
According to this configuration, the equipment cost is significantly reduced as compared with the case where a separate power supply is installed for each of the main electrode and the auxiliary electrode.

(5) The plate assembly has a zinc-based plating layer on at least one of the outermost layers and does not have a zinc-based plating layer on the intermediate layer (including the case where the intermediate layer is not provided), (1). The resistance spot welding apparatus according to any one of (4).
According to this configuration, a plate set composed of three steel plates including a galvanized steel plate can be satisfactorily spot-welded by resistance spot welding without LME defects.

(6) A resistance spot welding method in which resistance spot welding is performed on a plate set in which at least one of a plurality of stacked steel plates has a zinc-based plating layer.
Between a set of electrodes that are arranged to face each other and each have a main electrode, at least one of which is placed in the vicinity of the main electrode and has an auxiliary electrode that can move independently of the main electrode. The process of arranging the board and
A step of partially removing the zinc-based plating layer by energizing between the main electrode and the auxiliary electrode arranged in the vicinity thereof, and
A step of joining the plate assembly by resistance spot welding by energizing between the pair of main electrodes while pressurizing the plate assembly.
A resistance spot welding method.

According to this configuration, it is possible to perform resistance spot welding of a steel plate in which at least one of the plurality of steel plates has a zinc-based plating layer without welding defects.

(7) The resistance spot welding method according to (6), wherein the step of partially removing the zinc-based plating layer is performed in a state where the electrode on the non-energized side is in contact with the plate assembly. ..
According to this configuration, when the zinc-based plating layer is removed, the electrode is brought into contact with the plate assembly to be in the standby state, so that the subsequent step of resistance spot welding of the plate assembly can be performed immediately, and welding can be performed. Efficiency is improved.

(8) The resistance spot welding method according to (6) or (7), wherein each of the auxiliary electrodes is formed in a ring shape so as to surround the main electrode arranged in the vicinity thereof.
According to this configuration, the heating region and the exposed region are also circular, and an ideal evaporation state of zinc can be created. Therefore, the zinc-based plating layer can be removed in a shape suitable for the subsequent resistance spot welding. .. In addition, the zinc-based plating layer can be removed only in the vicinity of the resistance spot welded range, and the deterioration of the anticorrosion effect can be suppressed.

(9) The energization performed between the main electrode and the auxiliary electrodes arranged in the vicinity thereof, or between the set of main electrodes is between one power source and the main electrode or the auxiliary electrode. The resistance spot welding method according to any one of (6) to (8), which is performed by switching a switch for connecting or disconnecting each electric path.
According to this configuration, the cost of the power supply equipment is reduced, and by switching the switch, the zinc-based plating layer can be easily removed and the resistance spot welding of the plate assembly can be easily performed.

(10) The plate assembly has a zinc-based plating layer on at least one of the outermost layers and does not have a zinc-based plating layer on the intermediate layer (including the case where the intermediate layer is not provided), (6). The resistance spot welding method according to any one of (9).
According to this configuration, a plate set composed of three steel plates including a galvanized steel plate can be satisfactorily spot-welded by resistance spot welding without LME defects.

(11) A resistance spot welding apparatus for performing resistance spot welding on a plate set in which at least one of a plurality of stacked steel plates has a zinc-based plating layer.
It is provided with a first composite electrode and a second composite electrode which are arranged so as to sandwich the plate assembly and can be moved so as to approach or separate from each other.
The first composite electrode has a first welding electrode and a first auxiliary electrode that is arranged in the vicinity of the first welding electrode and can move independently of the first welding electrode.
The second composite electrode has a second weld electrode and a second auxiliary electrode that is arranged in the vicinity of the second weld electrode and can move independently of the second weld electrode.
Energization is possible between the first welding electrode and the first auxiliary electrode, between the second welding electrode and the second auxiliary electrode, and between the first welding electrode and the second welding electrode. A resistance spot welding device equipped with an additional power source.

According to this configuration, a plate set in which at least one steel plate has a zinc-based plating layer is arranged between the first composite electrode and the second composite electrode, and between the first welding electrode and the first auxiliary electrode, After removing the zinc plating layer by energizing at least one of the second welding electrode and the second auxiliary electrode, the plate assembly is pressurized between the first welding electrode and the second welding electrode. Since the plate assembly is subjected to resistance spot welding by energizing, the plate assembly in which at least one of the plurality of steel plates has a zinc-based plating layer can be resistance spot welded without welding defects.

Further, in the case of joining a plate set in which a plurality of galvanized steel sheets having a galvanized layer are superposed by resistance spot welding, between the first welding electrode and the first auxiliary electrode, and with the second welding electrode. Since it is possible to energize between the second auxiliary electrode, a plate set consisting of a plurality of galvanized steel sheets (particularly, when both of the outermost steel sheets of the plate set have a galvanized layer). Even if there is, the galvanized layers of a plurality of galvanized steel sheets can be removed, and resistance spot welding can be performed without welding defects.

(12) Energization between the first welding electrode and the first auxiliary electrode, energization between the second welding electrode and the second auxiliary electrode, or between the first welding electrode and the second welding electrode. The resistance spot welding apparatus according to (11), further comprising a control unit capable of switching between energization and energization.
According to this configuration, the control unit can switch between removing the zinc-based plating layer from the zinc-based plated steel sheet and resistance spot welding of the zinc-based plated steel sheet.

(13) The first auxiliary electrode and the second auxiliary electrode are formed in a ring shape so as to surround the first welding electrode and the second welding electrode, respectively, according to (11) or (12). Resistance spot welding equipment.
According to this configuration, the heating region and the exposed region are also circular, and an ideal evaporation state of zinc can be created. Therefore, the zinc-based plating layer can be removed in a shape suitable for the subsequent resistance spot welding. .. In addition, the zinc-based plating layer can be removed only in the vicinity of the resistance spot welded range, and the deterioration of the anticorrosion effect can be suppressed.

(14) A switch that connects or cuts off each electric path to each electric path between the power source and the first welding electrode, the first auxiliary electrode, the second welding electrode, or the second auxiliary electrode. The resistance spot welding apparatus according to any one of (11) to (13), respectively.
According to this configuration, by switching the switch, it is possible to easily remove the zinc-based plating layer from the zinc-based plated steel sheet and perform resistance spot welding of the plate assembly.

(15) The resistance spot welding apparatus according to any one of (11) to (14), wherein the power source is one.
According to this configuration, the equipment cost is significantly reduced as compared with the case where individual power supplies are installed for each of the first welding electrode, the first auxiliary electrode, the second welding electrode, and the second auxiliary electrode.

(16) The plate assembly has a zinc-based plating layer on at least one of the outermost layers and does not have a zinc-based plating layer on the intermediate layer (including the case where the intermediate layer is not provided), (11). The resistance spot welding apparatus according to any one of (15).
According to this configuration, a plate assembly composed of three steel plates including a galvanized steel plate can be satisfactorily spot-welded by resistance spot welding without welding defects.

(17) A resistance spot welding method in which resistance spot welding is performed on a plate assembly in which at least one of a plurality of stacked steel plates has a zinc-based plating layer.
A first composite electrode having a first auxiliary electrode which is arranged to face each other and is arranged in the vicinity of the first welding electrode and the first welding electrode and can move independently of the first welding electrode, and a second welding electrode. And the step of arranging the plate assembly between the second welding electrode and the second composite electrode having the second auxiliary electrode that can move independently from the second welding electrode.
The zinc-based plating layer is partially removed by energizing at least one between the first welding electrode and the first auxiliary electrode and between the second welding electrode and the second auxiliary electrode. Process and
A step of joining the plate assembly by resistance spot welding by energizing between the first welding electrode and the second welding electrode while pressurizing the plate assembly.
A resistance spot welding method.

According to this configuration, a plate set in which at least one steel plate has a zinc-based plating layer is arranged between the first composite electrode and the second composite electrode, and between the first welding electrode and the first auxiliary electrode, After removing the zinc plating layer by energizing at least one of the second welding electrode and the second auxiliary electrode, the plate assembly is pressurized between the first welding electrode and the second welding electrode. Since the plate assembly is subjected to resistance spot welding by energizing, the plate assembly in which at least one of the plurality of steel plates has a zinc-based plating layer can be resistance spot welded without welding defects.

Further, in the case of joining a plate set in which a plurality of galvanized steel sheets having a galvanized layer are superposed by resistance spot welding, between the first welding electrode and the first auxiliary electrode, and with the second welding electrode. Since it is possible to energize between the second auxiliary electrode, a plate set consisting of a plurality of galvanized steel sheets (particularly, when both of the outermost steel sheets of the plate set have a galvanized layer). Even if there is, the galvanized layers of a plurality of galvanized steel sheets can be removed, and resistance spot welding can be performed without welding defects.

(18) In the step of partially removing the zinc-based plating layer, the first welding electrode and the first auxiliary electrode, or the second welding electrode and the second auxiliary electrode on the non-energized side are removed. The resistance spot welding method according to (17), which is performed in a state of being in contact with the plate assembly.
According to this configuration, when the zinc-based plating layer is removed, the electrode is brought into contact with the plate assembly to be in the standby state, so that the subsequent step of resistance spot welding of the plate assembly can be performed immediately, and welding can be performed. Efficiency is improved.

(19) When both the outermost steel sheets in the plate assembly have a zinc-based plating layer,
The resistance spot welding method according to (17) or (18), wherein energization is not performed simultaneously between the first welding electrode and the first auxiliary electrode, and between the second welding electrode and the second auxiliary electrode. ..
According to this configuration, in the step of removing the zinc-based plating layer, energization between the upper and lower zinc-based plated steel sheets is prevented, so that the uneven temperature rise is suppressed and the zinc evaporation is stable without becoming unstable. Can be removed.

(20) As the first auxiliary electrode and the second auxiliary electrode, those formed in a ring shape so as to surround the first welding electrode and the second welding electrode are used, respectively, (17) to (19). ). The resistance spot welding method according to any one of.
According to this configuration, the heating region and the exposed region are also circular, and an ideal evaporation state of zinc can be created. Therefore, the zinc-based plating layer can be removed in a shape suitable for the subsequent resistance spot welding. .. Further, the zinc-based plating layer only in the vicinity of the resistance spot welded range can be removed, and the deterioration of the anticorrosion effect can be suppressed.

(21) It is performed between the first welding electrode and the first auxiliary electrode, between the second welding electrode and the second auxiliary electrode, or between the first welding electrode and the second welding electrode. Energization is performed by switching a switch that connects or cuts off each electric path between one power source and the first welding electrode, the first auxiliary electrode, the second welding electrode, or the second auxiliary electrode. The resistance spot welding method according to any one of (17) to (20).
According to this configuration, the cost of the power supply equipment is reduced, and by switching the switch, the zinc-based plating layer can be easily removed and the resistance spot welding of the plate assembly can be easily performed.

(22) The plate assembly has a zinc-based plating layer on at least one of the outermost layers and does not have a zinc-based plating layer on the intermediate layer (including the case where the intermediate layer is not provided), (17). , (18), (20) or (21). The resistance spot welding method according to any one of (18), (20) and (21).
According to this configuration, a plate set composed of three steel plates including a galvanized steel plate can be satisfactorily spot-welded by resistance spot welding without LME defects.

10,10A Resistance spot welding equipment 20 Plate assembly 30,30A, 30B Galvanized steel plate (steel plate)
31 Zinc-based plating layer 32 Heating region 33 Exposed region 34 Nugget 40 Steel plate (steel plate) without zinc-based plating layer
50 First composite electrode (electrode)
51 Main electrode (first welding electrode)
52 Auxiliary electrode (1st auxiliary electrode)
60 Second composite electrode (electrode)
61 Main electrode (second welding electrode)
62 Second auxiliary electrode 70 Power supply 71, 72, 73, 74 Electrical path 75, 76, 77, 78 Switch (control unit)

Claims (22)

A resistance spot welding apparatus for performing resistance spot welding on a sheet structure in which at least one of a plurality of superposed steel sheets has a zinc-based plating layer.
It is provided with a set of electrodes that are arranged so as to sandwich the plate assembly and can be moved so as to approach or separate from each other.
Each of the pair of electrodes has a main electrode and
At least one of the pair of electrodes has an auxiliary electrode that is located in the vicinity of the main electrode and can move independently of the main electrode.
A power source capable of energizing between the main electrode and the auxiliary electrodes arranged in the vicinity thereof and between a set of the main electrodes is provided.
A resistance spot welding apparatus further comprising a control unit capable of switching between energization between the main electrode and the auxiliary electrodes arranged in the vicinity thereof, or energization between a set of the main electrodes. The resistance spot welding apparatus according to claim 1, wherein the auxiliary electrode is formed in a ring shape so as to surround the main electrode arranged in the vicinity thereof. The resistance spot welding apparatus according to claim 1 or 2, wherein each electric path between the power source and the main electrode or the auxiliary electrode is provided with a switch for connecting or disconnecting the respective electric paths. The resistance spot welding apparatus according to any one of claims 1 to 3, wherein the power source is one. The plate assembly has a zinc-based plating layer on at least one of the outermost layers, and does not have a zinc-based plating layer on the intermediate layer (including the case where the intermediate layer is not provided), claim 1 to 4. The resistance spot welding apparatus according to any one item. This is a resistance spot welding method in which resistance spot welding is performed on a steel plate having a zinc-based plating layer at least one of a plurality of superposed steel plates.
Between a set of electrodes that are arranged to face each other and each have a main electrode, at least one of which is placed in the vicinity of the main electrode and has an auxiliary electrode that can move independently of the main electrode. The process of arranging the board and
A step of partially removing the zinc-based plating layer by energizing between the main electrode and the auxiliary electrode arranged in the vicinity thereof, and
A step of joining the plate assembly by resistance spot welding by energizing between the pair of main electrodes while pressurizing the plate assembly.
A resistance spot welding method. The resistance spot welding method according to claim 6, wherein the step of partially removing the zinc-based plating layer is performed in a state where the electrode on the non-energized side is in contact with the plate assembly. The resistance spot welding method according to claim 6 or 7, wherein as the auxiliary electrode, one formed in a ring shape so as to surround the main electrode arranged in the vicinity thereof is used. The energization performed between the main electrode and the auxiliary electrodes arranged in the vicinity thereof or between the set of main electrodes is the electricity between one power supply and the main electrode or the auxiliary electrode. The resistance spot welding method according to any one of claims 6 to 8, which is performed by switching a switch for connecting or disconnecting the path. The plate assembly has a zinc-based plating layer on at least one of the outermost layers, and does not have a zinc-based plating layer on the intermediate layer (including the case where the intermediate layer is not provided), claim 6 to 9. The resistance spot welding method according to any one item. A resistance spot welding apparatus for performing resistance spot welding on a sheet structure in which at least one of a plurality of superposed steel sheets has a zinc-based plating layer.
It is provided with a first composite electrode and a second composite electrode which are arranged so as to sandwich the plate assembly and can be moved so as to approach or separate from each other.
The first composite electrode has a first welding electrode and a first auxiliary electrode that is arranged in the vicinity of the first welding electrode and can move independently of the first welding electrode.
The second composite electrode has a second weld electrode and a second auxiliary electrode that is arranged in the vicinity of the second weld electrode and can move independently of the second weld electrode.
Energization is possible between the first welding electrode and the first auxiliary electrode, between the second welding electrode and the second auxiliary electrode, and between the first welding electrode and the second welding electrode. A resistance spot welding device equipped with an additional power source. Energization between the first welding electrode and the first auxiliary electrode, energization between the second welding electrode and the second auxiliary electrode, or between the first welding electrode and the second welding electrode. The resistance spot welding apparatus according to claim 11, further comprising a control unit capable of switching to energization. The resistance spot welding apparatus according to claim 11 or 12, wherein the first auxiliary electrode and the second auxiliary electrode are formed in a ring shape so as to surround the first welding electrode and the second welding electrode, respectively. .. Each electric path between the power source and the first welding electrode, the first auxiliary electrode, the second welding electrode, or the second auxiliary electrode is provided with a switch for connecting or disconnecting the respective electric paths. The resistance spot welding apparatus according to any one of claims 11 to 13. The resistance spot welding apparatus according to any one of claims 11 to 14, wherein the power source is one. The plate assembly has a zinc-based plating layer on at least one of the outermost layers, and does not have a zinc-based plating layer on the intermediate layer (including the case where the intermediate layer is not provided), claim 11 to 15. The resistance spot welding apparatus according to any one item. This is a resistance spot welding method in which resistance spot welding is performed on a steel plate having a zinc-based plating layer at least one of a plurality of superposed steel plates.
A first composite electrode having a first auxiliary electrode which is arranged to face each other and is arranged in the vicinity of the first welding electrode and the first welding electrode and can move independently of the first welding electrode, and a second welding electrode. And the step of arranging the plate assembly between the second welding electrode and the second composite electrode having the second auxiliary electrode that can move independently from the second welding electrode.
The zinc-based plating layer is partially removed by energizing at least one between the first welding electrode and the first auxiliary electrode and between the second welding electrode and the second auxiliary electrode. Process and
A step of joining the plate assembly by resistance spot welding by energizing between the first welding electrode and the second welding electrode while pressurizing the plate assembly.
A resistance spot welding method. In the step of partially removing the zinc-based plating layer, the first welding electrode and the first auxiliary electrode, or the second welding electrode and the second auxiliary electrode on the non-energized side are removed from the plate. The resistance spot welding method according to claim 17, which is performed in a state of being in contact with the set. When both the outermost steel sheets in the plate assembly have a zinc-based plating layer,
The resistance spot welding method according to claim 17 or 18, wherein energization is not performed simultaneously between the first welding electrode and the first auxiliary electrode, and between the second welding electrode and the second auxiliary electrode. Any one of claims 17 to 19, wherein as the first auxiliary electrode and the second auxiliary electrode, those formed in a ring shape so as to surround the first welding electrode and the second welding electrode are used. The resistance spot welding method described in the section. The energization performed between the first welding electrode and the first auxiliary electrode, between the second welding electrode and the second auxiliary electrode, or between the first welding electrode and the second welding electrode is. A claim made by switching a switch that connects or cuts off each electric path between one power source and the first welding electrode, the first auxiliary electrode, the second welding electrode, or the second auxiliary electrode. Item 2. The resistance spot welding method according to any one of Items 17 to 20. The plate assembly has a zinc-based plating layer on at least one of the outermost layers, and does not have a zinc-based plating layer on the intermediate layer (including the case where the intermediate layer is not provided), claims 17 and 18. The resistance spot welding method according to any one of 20 and 21.

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