JP6670873B2 - Electrodes for welding galvanized steel sheets and seam welding equipment for galvanized steel sheets - Google Patents

Description

  The present invention relates to a galvanized steel sheet welding electrode and a galvanized steel sheet seam welding apparatus.

Conventionally, it is known to use tungsten or molybdenum instead of copper for the material of the seam welding electrode of a plated steel plate (for example, see Patent Document 1). In Patent Document 1, in order to prevent electrode cracking, an electrode core material is made of sintered bonding gold produced by sintering tungsten or molybdenum powder, and it is buried in a roller and integrated, and the core material is made of a copper electrode body. It had a double structure surrounding it.
Conventionally, in order to assist heat conduction from the electrode contact surface to the outer periphery of the electrode, a cooling water passage is provided in the electrode mounting shaft, and water is circulated from the internal cooling water passage on both the front and back surfaces of the roller electrode to cool the roller electrode. Is also known (for example, see Patent Document 2).

JP 2007-260718 A Japanese Patent No. 3909193

As in Patent Literature 1, by adopting a double structure in which a sintered metal core of tungsten or molybdenum is surrounded by a copper electrode body, the copper of the electrode body is melted and iron is used as a base material of a galvanized steel sheet. The cooling effect is enhanced by utilizing the thermal conductivity of copper while preventing the phenomenon of melting and alloying into the alloy, so-called "copper insertion", but both the sintered core material and the copper electrode are worn away during use. In such a case, the entire system must be replaced, which increases the running cost.
In the case of cooling both the front and rear surfaces of the roller electrode with internal cooling water as in Patent Literature 2, the electrode portion of the roller electrode is close to the contact surface of the electrode, so that the outer peripheral edge of the electrode has high heat and is cooled. Easy to run short. In addition, when an electrode material other than copper is used as the electrode material, there are problems in maintaining welding quality such as insufficient cooling and a decrease in welding current due to an oxide layer.
The present invention has been made in view of the above-described circumstances, and the heat conductivity of the electrode outer periphery and the cooling property of the electrode are improved, and the quality of galvanized steel sheet seam welding can be improved. It is an object to provide a welding electrode and a seam welding device.

The present invention relates to a galvanized steel sheet welding electrode for seam welding while cooling a joining flange part (101a, 102a) of a galvanized steel sheet with a cooling medium. And a plate-shaped outer peripheral surface (21b, 22b) on at least both sides on the outer peripheral edge (21a, 22a) side of the electrode body (21, 22). , 22b) are provided with a chromium or nickel-based coating layer (23, 24).

  In the above invention, the coating layers (23, 24) may be a chromium film in which chromium is saturated with nitrogen.

  Further, in the above invention, a conductive member (21 d, 22 d) having a mounting portion (21 d, 22 d) at a radially central side of the electrode body (21, 22) and having a higher thermal conductivity than the electrode body (21, 22) The electrode body portions (21, 22) and the conductive members (31, 41) may be coupled and separable in a state where the electrode body portions (31, 41) are in contact with each other.

  Further, in the above invention, annular concave portions (22e, 122e) may be formed on the radially inner peripheral side of the electrode body portions (21, 22).

  The present invention relates to a galvanized steel sheet seam welding apparatus for seam-welding a joining flange part (101a, 102a) of a galvanized steel sheet formed by press forming, wherein an outer peripheral part (21b, 22b) of a roller electrode (21, 22) is formed. It is characterized in that coating layers (23, 24) are provided on both side surfaces, and the coating layers (23, 24) can be welded by cooling with a cooling medium from above.

  In the above invention, the cooling medium is used as cooling water, and cooling water is sprayed toward both ends of the galvanized steel sheet with the joining flanges (101a, 102a) interposed therebetween to form a roller electrode (21, 22) and a steel sheet. May be simultaneously cooled.

  Further, in the above invention, the cutting means (52, 72) is reciprocally oscillated along the electrode rotating direction of the roller electrodes (21, 22), and the roller electrodes (21, 22) contacted by the cutting means (52, 72). ) May be welded while dressing the contact surfaces (21a, 22a).

  Further, in the above invention, the roller electrodes (21, 22), the cooling medium injection means (10), and the cutting means (52, 72) may be integrated into a base (20) of the welding unit (5).

In the above invention, the thickness of one of the roller electrodes (21, 22) is t1, the outer diameter is d1, and the thickness of the other roller electrode (22) is t2. When the diameter is d2, t1, d1, t2, and d2 may be set so as to satisfy the following relational expression t1 · d1 ^1/2 = t2 · d2 ^1/2 .

  The welding electrode of the galvanized steel sheet according to the present invention is a welding electrode of a galvanized steel sheet for seam welding a joining flange portion of a galvanized steel sheet, wherein the electrode body part of the seam welding is made of a molybdenum or tungsten material having a disc shape, At least both side surfaces on the outer peripheral edge side of the electrode main body are provided with a plate-shaped outer peripheral surface, and a chromium or nickel-based coating layer is provided on the plate-shaped outer peripheral surface. According to this configuration, it is possible to eliminate a decrease in welding current due to thermal conductivity of the electrode outer peripheral portion and rusting of the electrode, to enable water cooling, and to improve the quality of seam welding of a galvanized steel sheet.

  In the above invention, the coating layer may be a chromium film in which chromium is saturated with nitrogen. According to this configuration, since the chromium layer is saturated with nitrogen, the peel strength in a high heat state can be improved, and the durability of the electrode can be improved.

  Further, in the above invention, the electrode body portion and the conductive member have a mounting portion at a radially central side of the electrode body portion, and a conductive member having a higher thermal conductivity than the electrode body portion is brought into contact with the mounting portion. May be combined and separable. According to this configuration, a conductive member having a higher thermal conductivity than the electrode is brought into contact with the center in the radial direction of the electrode so that the electrode can be separated from the electrode.

  Further, in the above invention, an annular concave portion may be formed on a radially inner peripheral side of the electrode main body. According to this configuration, the area of the contact surface between the electrode body and the conductive member can be increased by the annular concave portion, the heat of the electrode is transmitted to the holding member having high thermal conductivity, and cracking due to thermal stress of the electrode is prevented. be able to.

  A galvanized steel sheet seam welding apparatus according to the present invention is a galvanized steel sheet seam welding apparatus for seam-welding a joining flange portion of a galvanized steel sheet formed by press forming, wherein a coating layer is formed on both side surfaces of an outer peripheral portion of a roller electrode. It was made to be weldable by cooling with a cooling medium from above the coating layer. According to this configuration, a cooling medium is injected from the outside of the coating layer of the electrode to the electrode in contact with the joining flange portion of the galvanized steel sheet to cool the electrode and the joining flange portion. Cooling can be performed while preventing corrosion of the electrode, and cooling efficiency can be improved, and thermal deformation of the press-formed steel plate can be prevented.

  In the above invention, the cooling medium may be used as cooling water, and cooling water may be sprayed from both sides of the joining flange portion of the galvanized steel sheet toward the tip of the electrode to simultaneously cool the roller electrode and the steel sheet. According to this configuration, cooling water is sprayed from both sides of the joining flange portion toward the electrode tip to cool the electrode and the flange portion, so that it is possible to further prevent thermal deformation of the press-formed steel plate, and Cooling properties are further improved, and welding quality and electrode durability are improved.

  Further, in the above invention, welding may be performed while dressing a contact surface of the roller electrode with which the cutting means abuts by reciprocating the cutting means along an electrode rotating direction of the roller electrode. According to this configuration, by vibrating the cutting means to scrape off the outer peripheral surface of the electrode, it is possible to efficiently remove deposits attached to the electrode as a lump and smoothen the surface of the electrode, thereby further improving welding quality. .

  Further, in the above invention, the roller electrode, the cooling medium injection unit, and the cutting unit may be integrated with a base of a welding unit. According to this configuration, it is possible to reduce the size of the seam welding apparatus for galvanized steel sheets.

In the above invention, when the thickness of one of the roller electrodes is t1 and the outer diameter is d1, and the thickness of the other roller electrode is t2 and the outer diameter is d2, the following relationship is established. T1, d1, t2, and d2 may be set so as to satisfy the expression t1 · d1 ^1/2 = t2 · d2 ^1/2 . According to this configuration, since the balance of the current density is secured, the current value width of the seam welding can be widened, and the welding quality is improved.

It is an explanatory view of a seam welding device of a first embodiment according to the present invention. It is a front view of a welding unit. FIG. 3 is a sectional view taken along line III-III of FIG. 2 showing a large roller electrode. FIG. 4 is a sectional view taken along line IV-IV of FIG. 2 showing a small roller electrode. It is explanatory drawing of the relationship between the plate thickness of a large roller electrode and the plate thickness of a small roller electrode. It is a sectional view of a small roller electrode of a 2nd embodiment concerning the present invention. It is an exploded perspective view of a fuel tank provided for an embodiment concerning the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description, directions such as left and right and up and down are the same as directions with respect to the drawings unless otherwise specified.

<First embodiment>
FIG. 1 is an explanatory diagram of a seam welding apparatus 1 according to a first embodiment of the present invention.
Here, a fuel tank (work) 100 provided in a motorcycle (not shown) is illustrated as the work 100 provided to the seam welding apparatus 1.
As shown in FIG. 7, the fuel tank 100 is composed of a pair of bowl-shaped halves 101 and 102 having a container shape. The halves 101 and 102 are made of a copper (Cu) plate plated with zinc (Zn). The halves 101 and 102 are formed in a bowl shape by pressing a copper plate. At the open ends of the halves 101 and 102, flange-shaped joining flange portions 101a and 102a are formed.
The joining flange portions 101a and 102a are tentatively assembled in the container-shaped fuel tank 100 by being opposed to each other and overlapped. As shown in FIG. 1, the joint flange portions 101a and 102a of the temporarily assembled fuel tank 100 are seam-welded, so that the half bodies 101 and 102 are integrated to form the fuel tank 100. The fuel tank to be seam-welded is not limited to the fuel tank 100 having the shape shown in FIG.

As shown in FIG. 1, the seam welding apparatus 1 is an apparatus for seam welding a joining flange portion of a galvanized steel sheet formed by press forming.
The seam welding apparatus 1 includes a gripping robot 2 that grips the temporarily assembled workpiece 100 before seam welding, and a welding robot 3 that seam-welds the workpiece 100 gripped by the gripping robot 2.

The gripping robot 2 is an articulated robot in which a plurality of arms 2a are rotatable about axes. The welding robot 3 is an articulated robot in which a plurality of arms 3a are rotatable about axes. The positions and postures of the arms 2a and 3a of the robots 2 and 3 are controlled by control units 2b and 3b respectively provided.
The control unit 2b of the gripping robot 2 and the control unit 3b of the welding robot 3 are connected by a communication line 6. The gripping robot 2 includes a clamp unit 4 supported at the tip of the arm 2a, and the clamp unit 4 grips the workpiece 100. The welding robot 3 includes a welding unit 5 supported at the tip of the arm 3a, and the welding unit 5 performs seam welding on the workpiece 100. The grasping robot 2 controls the posture of the workpiece 100, and the welding robot 3 performs seam welding on the workpiece 100 in cooperation therewith.

  The clamp unit 4 of the gripping robot 2 includes a pair of clamp arms 4a and 4b and a positioning unit 4c. The gripping robot 2 clamps the outer surface of the fuel tank 100 temporarily assembled by the pair of clamp arms 4a and 4b. In addition, the gripping robot 2 inserts the positioning portion 4c into the fuel supply port 101c provided in the half body 101, and takes out the position of the fuel tank 100 sandwiched between the clamp arms 4a and 4b.

The welding unit 5 of the welding robot 3 supports a pair of roller electrodes 21 and 22. In FIG. 1, the roller electrodes 21 and 22 are provided with a dot pattern so that they are easy to see. The roller electrodes 21 and 22 are formed in a disk shape. The roller electrodes 21 and 22 are supported on electrode shafts 30 and 40. The electrode shafts 30 and 40 are rotatably supported. The driving force is transmitted to the electrode shafts 30 and 40 from the shaft driving means 25 and 26, and the electrode shafts 30 and 40 are driven to rotate, and the roller electrodes 21 and 22 rotate at the set speed.
The roller electrodes 21 and 22 are configured such that their opposing electrode tips can approach and separate from each other, and rotate with the roller electrodes 21 and 22 sandwiching the joining flange portions 101a and 102a of the fuel tank 100.

  In the gripping robot 2 and the welding robot 3, the roller electrodes 21 and 22 sandwich the joining flange portions 101 a and 102 a, and the roller electrodes 21 and 22 are disposed along the joining flange portions 101 a and 102 a in a fixed direction along the fuel tank 100 (hereinafter, referred to as “the fuel tank 100”). The position and the direction of the arms 2a and 3a are controlled so as to correspond to the movement of the work 2).

A cooling device 7 is attached to the welding robot 3.
The cooling device 7 includes a main tank 8 that stores cooling water (cooling medium). A hose 9 extending along the arm 3a is connected to the main tank 8. The hose 9 extends toward the tip of the arm 3a and is connected to a cooling water injection device (cooling medium injection means) 10 of the welding unit 5.
The cooling device 7 supplies cooling water from the main tank 8 to the cooling water injection device 10 by a high-pressure pump (not shown), and causes the cooling water injection device 10 to inject the cooling water. The cooling device 7 cools the roller electrodes 21 and 22 and the joining flange portions 101a and 102a.
The seam welding apparatus 1 cools the roller electrodes 21 and 22 and the joining flange portions 101a and 102a during seam welding.

FIG. 2 is a front view of the welding unit 5.
The welding unit 5 includes a base 20 supported by the arm 3a of the welding robot 3.
Large and small roller electrodes 21 and 22 are rotatably supported on the base 20. Driving force is transmitted to the large roller electrode 21 having a large diameter via the electrode shaft 30, and the large roller electrode 21 rotates in the direction indicated by the arrow A1. The driving force is transmitted to the small roller electrode 22 having a small diameter via the electrode shaft 40, and the small roller electrode 22 rotates in the direction indicated by the arrow A2.
As shown in FIG. 7 and FIG. 1 by way of a two-dot chain line for explanation, the diameter of the small roller electrode 22 is set to a size that can fit in the inner peripheral portion 102b of the large curvature portion of the joining flange portions 101a and 102a of the work 100. , Can follow the shape of the joining flange portions 101a and 102a extending in a two-dimensional curved shape. The size of both electrodes can be the same diameter, but as in the present embodiment, the joining flange portions 101a and 102a may be sandwiched between the large roller electrode 21 and the small roller electrode 22. It is possible.

  The electrode shafts 30 and 40 are electrically connected to a welding power source (not shown), and a current flows between the roller electrodes 21 and 22 via the electrode shafts 30 and 40. At the welding position P where the large roller electrode 21 and the small roller electrode 22 are pressed against each other, the joining flange portions 101a and 102a of the fuel tank 100 are melted by resistance heat when current flows while being pressurized, and the joining flange portion 101a of the galvanized steel plate. , 102a are melted together to perform seam welding.

  In the present embodiment, the roller electrodes (electrode body portions) 21 and 22 are made of a disk-shaped molybdenum (Mo) material of molybdenum or molybdenum alloy. However, the roller electrodes 21 and 22 may be made of a tungsten (W) material of tungsten or a tungsten alloy instead of the molybdenum material. By using molybdenum or tungsten for the roller electrodes 21 and 22, it is possible to eliminate the problem that copper melts out and enters the galvanized steel sheet when welding the galvanized steel sheet with the copper electrode, so-called copper insertion. .

On the outer surfaces of the disk-shaped roller electrodes 21 and 22, coating layers 23 and 24 are formed. The coating layers 23 and 24 are formed on the entire outer surfaces of the roller electrodes 21 and 22. However, the coating layers 23 and 24 may be formed not on the entire outer surface but on the outer peripheral portions (flat outer peripheral surfaces) 21b and 22b, which are the side surfaces on both sides of the outer peripheral surfaces (outer peripheral edges) 21a and 22a.
Incidentally, even if the coating layers 23 and 24 are formed on the outer peripheral surfaces (outer peripheral edges) 21a and 22a which are the pressure contact surfaces of the roller electrodes 21 and 22, they are not melted when used. In addition, before the use of the electrode, the presence of the coating layers 23 and 24 serves as a rust-preventive film, which eliminates the need for rust-preventive treatment during storage.
The coating layers 23 and 24 are dry coatings. As the dry film, a chromium (Cr) film in which nitrogen (N) is supersaturated is preferable. This chromium film is formed by a sputtering process at a processing temperature of 200 to 300 ° C. The chromium film is tissue is solid solution _{(Cr + N) + Cr x} N y, Hv hardness is 1500 to 2000, the coefficient of friction due to the ruby ball is 0.20 to 0.30. The thickness of the coating layers 23 and 24 is preferably 3 to 4 μm.

Since the dry film is a film having high adhesion that is hardly cracked or peeled off, the dry film layers 23 and 24 can prevent the roller electrodes 21 and 22 from being damaged or cracked during use. Further, since the roller electrodes 21 and 22 are protected from the outside, it is possible to prevent the roller electrodes 21 and 22 from being oxidized by the cooling water and to prevent a reduction in welding current due to the oxide layer.
Further, since the coating layers 23 and 24 are dry coatings having a thickness of 3 to 4 μm and are thin, the large area of the roller electrodes 21 and 22 can be uniformly cooled without obstructing external cooling of the roller electrodes 21 and 22. Further, since the roller electrodes 21 and 22 are covered with the coating layers 23 and 24, the corrosion resistance against salt and the like contained in the cooling water is also improved.
In particular, since the coating layers 23 and 24 are saturated with nitrogen in the chromium layer, the peel strength in a high heat state can be improved, and the durability of the electrode can be improved.

  Although the coating layers 23 and 24 are described as being chromium-based coating layers, they may be nickel-based coating layers. PVD (Physical Vapor Deposition) processing such as sputtering or vacuum deposition is possible as the dry plating processing for forming a dry film. The components of the dry coating layer may be chromium or nickel.

The cooling water injection device (cooling medium injection means) 10 is supported on the base 20. The cooling water injection device 10 is arranged upstream of the welding position P in the traveling direction (the direction of the arrow A3) of the joining flange portions 101a and 102a. The traveling direction of the joining flange portions 101a and 102a is a traveling direction relative to the welding unit 5.
The cooling water injection device 10 includes a sub tank 11 connected to a hose 9 (see FIG. 1) extending from the main tank 8 (see FIG. 1), and a pair of injection nozzles 12 and 13 provided in the sub tank 11. The injection nozzles 12 and 13 are arranged in a pair on both sides of the moving position of the joining flange portions 101a and 101b. The injection nozzle 12 on one side injects the cooling water W1 from one side (upper side in FIG. 1) toward the welding position P. The other side injection nozzle 13 injects the cooling water W2 from the other side (the lower side in FIG. 1) toward the welding position P.

When seam welding is started, the cooling water injection device 10 of the cooling device 7 opens the valves (not shown) of the injection nozzles 12 and 13 and injects the cooling water W1 and W2 from the injection nozzles 12 and 13 to reduce the resistance heat. The formed joining flange portions 101a and 101b are cooled, and the roller electrodes 21 and 22 are cooled. When the seam welding is completed, the cooling water injection device 10 of the cooling device 7 closes the valves (not shown) of the injection nozzles 12 and 13 to stop the injection of the cooling water.
Since the roller electrodes 21 and 22 are cooled by the cooling water W1 and W2 from outside the coating layers 23 and 24, the seam welding apparatus 1 can cool the roller electrodes 21 and 22 while preventing corrosion. 22 has improved corrosion resistance. The press-formed steel plate has a characteristic of returning to a state before pressing by heat, but since the joining flange portions 101a and 101b are cooled by the cooling water W1 and W2, the heat of the press-formed fuel tank 100 is reduced. Deformation can be prevented, and welding quality and electrode durability are improved. Note that the roller electrodes 21 and 22 only need to have the coating layers 23 and 24 on the outer periphery, and the outer periphery does not have to be flat.

  A dressing unit 50 is supported on the base 20. The dressing unit 50 is disposed downstream of the welding position P in the rotation direction (the direction of the arrow A1) of the large roller electrode 21. The dressing unit 50 includes a vibration actuator (high-frequency vibration device) 51, a vibration tool (cutting means) 52 supported by the vibration actuator 51, and a downstream side in the rotation direction of the large roller electrode 21 with respect to the vibration tool 52. And a guide roller 53 disposed at The vibration actuator 51 vibrates at a high frequency when the large roller electrode 21 rotates. The vibration actuator 51 vibrates in the circumferential direction of the large roller electrode 21.

The vibration cutting tool 52 is a tool having a cutting edge 52a, and the cutting edge 52a is in contact with the outer peripheral surface 21a of the large roller electrode 21 at a predetermined pressure. The vibrating cutting tool 52 vibrates along the circumferential direction of the outer peripheral surface 21 a of the large roller electrode 21 by the vibration of the vibration actuator 51 to cut the outer peripheral surface 21 a and dress the large roller electrode 21. In addition, deposits such as welding spatters 103 attached to the large roller electrode 21 are removed.
The guide roller 53 contacts the outer peripheral surface 21 a of the large roller electrode 21 to position the vibration cutting tool 52. The guide roller 53 is disposed downstream of the vibration cutting tool 52 in the rotation direction of the large roller electrode 21. Since the guide roller 53 is in contact with the large roller electrode 21 after the dressing, the positioning accuracy is improved. The guide roller 53 has a shaping function of pressing the outer peripheral surface 21a after removing the spatter 103 attached to the outer peripheral surface 21a of the electrode with the vibrating cutting tool 52 to flatten the unevenness due to the cutting.

  A slide table 60 is supported on the base 20. The small roller electrode 22 is supported on the slide table 60 via the electrode shaft 40. The electrode shaft 40 is supported by the slide table 60 together with the shaft driving means 26 (see FIG. 2). The slide table 60 is supported so as to be able to approach and separate from the large roller electrode 21 via the slide rail 61 (in the direction of arrow A4).

  The gap P1 between the large roller electrode 21 and the small roller electrode 22 can be adjusted by moving the slide table 60 closer and further away, and the large roller electrode 21 and the small roller electrode 22 press the joining flange portions 101a and 102a. It is possible to change the power. A pressure cylinder (not shown) is connected to the slide table 60. The pressure cylinder is controlled at the end of welding and at the time of opening and closing, and the slide table 60 moves by the pressure of the pressure cylinder. Opening and closing and pressurization during welding are performed.

  A dressing unit 70 is supported on the slide table 60. The dressing unit 70 is disposed downstream of the small roller electrode 22 in the rotation direction (the direction of the arrow A2) with respect to the welding position P. The dressing unit 70 is configured similarly to the dressing unit 50 of the large roller electrode 21 except that the small roller electrode 22 is dressed. The vibration actuator (high-frequency vibration device) 71, vibration tool (cutting device main body) 72, and guide roller 73 of the dressing unit 70 function similarly to the vibration actuator 51, vibration tool 52, and the guide roller 53 of the dressing unit 50. , And functions on the small roller electrode 22. The dressing unit 70 slides integrally with the small roller electrode 22.

In the seam welding apparatus 1, when the roller electrodes 21 and 22 rotate while performing seam welding, the vibrating cutting tools 52 and 72 are reciprocally oscillated at high speed along the electrode rotation direction, while dressing the outer peripheral surfaces 21a and 22a. The welding is performed by the roller electrodes 21 and 22.
Since the melting point of molybdenum is higher than that of iron, the welding spatter 103 tends to adhere to the outer peripheral surfaces 21a and 22a as a lump without being melted into the roller electrodes 21 and 22 made of molybdenum. By vibrating and scraping the outer peripheral surfaces 21a and 22a of the roller electrodes 21 and 22, it is possible to remove adhered substances and smooth the surface.
The roller electrodes 21 and 22 are disk-shaped, and the thickness of the outer peripheral portions 21b and 22b is constant. Even when the outer peripheral surfaces 21a and 22a are dressed, the area in contact with the joining flange portions 101a and 102a is hard to change, and maintenance is easy.

  As described above, the welding unit 5 includes the base 20, and the base 20 includes the roller electrodes 21 and 22, the cooling water injection device 10, and the dressing units 50 and 70 including the vibrating tools 52 and 72. It is supported and unitized integrally. Since it is unitized, the seam welding apparatus 1 for galvanized steel sheets can be made compact.

FIG. 3 is a sectional view taken along the line III-III of FIG. 2 showing the large roller electrode 21, and FIG. 4 is a sectional view taken along the line IV-IV of FIG.
A plurality of mounting holes (mounting portions) 21d and 22d penetrating in the plate thickness direction are formed at the radial center of the roller electrodes 21 and 22, and penetrate in the plate thickness direction at the radial center of the roller electrodes 21 and 22. Cavities 21c and 22c are formed. With the holding members (conductive members) 31 and 41 entering the hollow portions 21c and 22c, the holding members 31 and 41 are attached by the fixing bolts 38 and 48 inserted into the attachment holes 21d and 22d.
The holding members 31 and 41 are conductive members having higher thermal conductivity than the roller electrodes 21 and 22. As a material of the holding members 31, 41, copper or a copper alloy is preferable. Since the roller electrodes 21 and 22 are supported by the electrode shafts 30 and 40 via the holding members 31 and 41, the cooling performance of heat generated in the roller electrodes 21 and 22 can be improved.

  As shown in FIG. 3, in the large roller electrode 21, the holding member 31 includes a ring-shaped base 32 supported by the electrode shaft 30 and a ring-shaped pressing part 33 supported by the base 32. Prepare. The base portion 32 and the pressing portion 33 are in contact with the large roller electrode 21 interposed therebetween, and hold the large roller electrode 21 from both sides in the axial direction. The large roller electrode 21 is sandwiched between the holding members 31 from both sides in the axial direction, and the holding member 31 having high heat conductivity and high conductivity is attached in a close contact state. The base portion 32 and the pressing portion 33 are set to the same outer diameter d31 which is smaller than the outer diameter d1 of the large roller electrode 21. Since the outer diameter d1 of the large roller electrode 21 is larger, the outer peripheral surface 21a and the outer peripheral portion (exposed cooling portion) 21b of the large roller electrode 21 sandwiched between the base 32 and the pressing portion 33 are exposed to the outside.

The base 32 includes an annular plate-shaped main body portion 32a that comes into contact with the electrode shaft 30 and an annular plate-shaped insertion portion 32b that is inserted into the hollow portion 21c of the large roller electrode 21. The outer diameter d32b of the insertion portion 32b is matched with the inner diameter r1 of the hollow portion 21c, and the inserted portion 32b is inserted into the hollow portion 21c and comes into contact with the inner peripheral portion of the hollow portion 21c.
The thickness t32b of the insertion portion 32b is set to be the same as the plate thickness t1 of the large roller electrode 21, and the insertion portion 32b forms a flat surface 34 with the axial side surface of the large roller electrode 21; The pressing portion 33 and the surface 34 are easily brought into contact with each other over the entire surface.
A plurality of fixing holes 32c penetrating in the plate thickness direction are formed in the base 32 corresponding to the positions of the insertion portions 32b. A fixing bolt 37 is inserted into the fixing hole 32c. The fixing bolt 37 is directly fixed to the front end surface of the electrode shaft 30, and the base 32 is fixed to the electrode shaft 30.

  The holding portion 33 and the base portion 32 are formed with mounting holes 33d and 32d which communicate with the mounting hole 21d of the large roller electrode 21. A plurality of mounting holes 21d, 33d, 32d are formed on the same circumference, and fixing bolts 38 are inserted into the mounting holes 21d, 33d, 32d (see FIG. 2). The fixing bolt 38 is fastened with a nut 39 at the tip. The holding member 31 and the large roller electrode 21 are integrated to form an assembly electrode 36. The assembly electrode 36 is configured to be detachable from the electrode shaft 30 with a fixing bolt 37. The large roller electrode 21, the base 32, the pressing part 33, the fixing bolt 38 and the nut 39 constitute an assembly electrode 36.

The inner diameter r33 of the holding portion 33 is smaller than the outer diameter d32b of the insertion portion 32b and larger than the diameter d32c on the circumference where the fixing hole 32c is arranged.
Since the inner diameter r33 of the holding portion 33 is smaller than the outer diameter d32b of the insertion portion 32b, the holding portion 33 comes into contact with the insertion portion 32b, and it is easy to secure high heat conduction and high conductivity.
Further, since the inner diameter r33 of the pressing portion 33 is larger than the diameter d32c of the circumference in which the fixing hole 32c is formed, it is possible to work on the fixing bolt 37 without removing the pressing portion 33 from the large roller electrode 21, It is detachable from the electrode shaft 30.

In the roller electrodes 21 and 22, thermal stress is generated inside the electrodes due to a difference in thermal expansion. Due to the presence of the hollow cavities 21c and 22c, the ratio of the length of the main body of the roller electrodes 21 and 22 to the length of the cavities 21c and 22c, that is, the ratio of the outer diameters d1 and d2 and the inner diameters r1 and r2 is reduced. By adjusting, the crack of the electrode can be suppressed and the durability of the electrode can be improved.
Even if the roller electrodes 21 and 22 are cracked, they can be easily replaced because they are assembled with the fixing bolts 37 and 38.

  As shown in FIG. 4, in the small roller electrode 22, the holding member 41 includes a disk-shaped base 42 supported by the electrode shaft 40 and a disk-shaped pressing part 43 supported by the base 42. The base portion 42 and the pressing portion 43 are in contact with the small roller electrode 22 interposed therebetween, and hold the small roller electrode 22 from both sides in the axial direction. The small roller electrode 22 is sandwiched between the holding members 41 from both sides in the axial direction, and the holding member 41 having high heat conductivity and high conductivity is attached in a close contact state. The base portion 42 and the pressing portion 43 are set to the same outer diameter d41 smaller than the outer diameter d2 of the small roller electrode 22. Since the outer diameter d2 of the small roller electrode 22 is larger, the outer peripheral surface 22a and the outer peripheral portion (exposed cooling portion) 22b of the small roller electrode 22 sandwiched between the base 42 and the pressing portion 43 are exposed to the outside.

The base 42 of the small roller electrode 22 includes a disk-shaped main body 42 a that contacts the electrode shaft 40. An annular projecting rib 42e is formed on the electrode shaft 40 side of the main body 42a. The protruding rib 42e protrudes toward the electrode shaft 40, and is fitted in an annular concave groove 40a provided on the distal end surface of the electrode shaft 40. When the protruding rib 42e fits into the concave groove 40a, it is positioned and the contact area increases.
An annular plate-shaped convex part 42f is formed on the pressing part 43 side of the main body part 42a. The convex portion 42f is formed corresponding to an annular concave portion (annular concave portion) 22e provided on the inner peripheral side of the small roller electrode 22, and fits into the concave portion 22e. The recess 22e is recessed in a direction to reduce the plate thickness t2 of the small roller electrode 22. The protrusion 42f fits into and contacts the recess 22e, so that the area of the contact surface between the small roller electrode 22 and the base 42 of the holding member 41 can be increased. It can be easily transmitted to the holding member 41 having high conductivity, and cracking due to thermal stress of the electrode can be prevented.

A disc-shaped insertion portion 42b to be inserted into the hollow portion 22c of the small roller electrode 22 is formed on the pressing portion 43 side of the projection 42f. The outer diameter d42b of the insertion portion 42b is adjusted to the inner diameter r2 of the hollow portion 22c, and when the insertion portion 42b is inserted into the hollow portion 22c, it comes into contact with the inner peripheral portion of the hollow portion 22c.
The thickness t42b of the insertion portion 42b is set to be the same as the axial length t22c of the hollow portion 22c of the small roller electrode 22, and the insertion portion 32b is flush with the axial side surface of the large roller electrode 21. And the surface 44 is easily brought into contact with the pressing portion 43 over the entire surface.

The holding portion 43 and the base portion 42 are formed with mounting holes 43d and 42d communicating with each other with the mounting hole 22d of the small roller electrode 22. A plurality of mounting holes 22d, 43d, 42d are formed on the same circumference, and fixing bolts 48 are inserted into the mounting holes 22d, 43d, 42d (see FIG. 2). The fixing bolt 48 is directly fixed to the front end surface of the electrode shaft 40, and the small roller electrode 22 and the holding member 41 are fixed to the electrode shaft 40.
With the electrode body 46 composed of the small roller electrode 22 and the holding member 41, the same operation and effect as those of the large roller electrode 21 and the holding member 31 can be obtained.

FIG. 5 is an explanatory diagram of the relationship between the plate thickness t1 of the large roller electrode 21 and the plate thickness t2 of the small roller electrode 22.
The plate thickness t2 of the small roller electrode 22 having the outer diameter d2 is formed larger than the plate thickness t1 of the large roller electrode 21 having the outer diameter d1.
The plate thicknesses t1 and t2 of the roller electrodes 21 and 22 are such that the contact area S1 where the large roller electrode 21 contacts the joining flange portion 101a and the contact area S2 where the small roller electrode 22 contacts the joining flange portion 101b are the same. Is set to
The sign also indicates a numerical value. The plate thicknesses t1 and t2 of the roller electrodes 21 and 22 are set based on a relational expression of t1 · d1 ^1/2 = t2 · d2 ^1/2 . It is preferable that the plate thicknesses t1 and t2 and the outer diameters d1 and d2 are set with higher accuracy than the order of 0.1 mm.

The above relational expression will be described.
At the welding position P, the large roller electrode 21 and the small roller electrode 22 are in contact with each other by pressing the joining flange portions 101a and 102a, respectively. It may be considered that the joining flange portions 101a and 102a are compressed by a minute thickness δ.

Here, the center of the large roller electrode 21 is C, and both ends in the circumferential direction where the large roller electrode 21 contacts the joining flange portion 101a are A and B. Then, a perpendicular line is drawn from the center C to the line AB, and the intersection with the circumference is D, and the intersection with the line AB is E.
Similarly, the center of the small roller electrode 22 is H, and both ends in the circumferential direction where the small roller electrode 22 contacts the joining flange portion 102a are F and G. Then, a perpendicular is drawn from the center H to the line FG, and an intersection with the circumference is I and an intersection with the line FG is J.
Hereinafter, the length connecting the position A and the position B is represented as AB.

The contact area S1 of the large roller electrode 21 is the product of AB and the plate thickness t1 (S1 = AB.t1).
AB is AB = AE + EB = 2 · AE, and from the theorem of three squares, AB = 2 · {AC ² −CE ² } ^1/2 = 2 · {AC ² − (CD−δ) ² } ^1/2 It is. Since AC = CD = d1 / 2, AB = 2 · [(d1 / 2) ² − {(d1 / 2) −δ} ² ] ^1/2 = 2 · ｛2 · (d1 / 2) · δ −δ ² ｝ ^1/2 .
Therefore, S1 = AB · t1 = 2 · ｛2 · (d1 / 2) · δ−δ ² ｝ ^1/2 · t1.
Similarly, the contact area S2 of the small roller electrode 22 is S2 = FG · t2 = 2 · {2 · (d2 / 2) · δ−δ ² } ^1/2 · t2.

If the contact area S1 and the contact area S2 is equal, S1 = S2 is a condition, 2 · {2 · (d1 / 2) · δ-δ 2} 1/2 · t1 = 2 · {2 · (d2 / 2) · δ−δ ² ｝ ^1/2 · t2. Since δ is close to 0, ignoring high-order minute amounts, d1 ^1/2 · t1 = d2 ^1/2 · t2.
Therefore, a relational expression of t1 · d1 ^1/2 = t2 · d2 ^1/2 is obtained.

  The heat conductivity of the molybdenum roller electrodes 21 and 22 is lower than that of copper, and the heat of the roller electrodes 21 and 22 is difficult to draw. By increasing the thickness t2 of the small roller electrode 22, the current density balance between the large roller electrode 21 and the small roller electrode 22 is ensured, and the scattering of the base material being locally heated and melted and dispersed is reduced. Can be suppressed, and the current value width used for welding can be widened. Therefore, the quality accuracy of seam welding is improved.

  As described above, in the first embodiment to which the present invention is applied, in the galvanized steel plate welding electrodes for seam welding the joint flange portions 101a and 102a of the galvanized steel plate, the seam-welded roller electrodes 21 and 22 are used. Is a disk-shaped molybdenum or tungsten material, plate-shaped outer peripheral portions 21b, 22b are formed on at least both outer peripheral surfaces 21a, 22a side of the roller electrodes 21, 22, and chromium or nickel-based outer peripheral portions 21b, 22b The coating layers 23 and 24 are provided. According to this configuration, the heat conductivity of the outer peripheral portions 21b and 22b of the roller electrodes 21 and 22 and the decrease in welding current due to rusting of the electrodes can be eliminated, water cooling can be performed, and seam welding of galvanized steel sheet can be performed. Quality can be improved.

  In the first embodiment, the coating layers 23 and 24 may be chromium films in which chromium is saturated with nitrogen. According to this configuration, since the chromium layer is saturated with nitrogen, the peel strength in a high heat state can be improved, and the durability of the electrode can be improved.

  Further, in the first embodiment, mounting members 21 d and 22 d are provided at the center in the radial direction of the roller electrodes 21 and 22, and the holding members 31 and 41 having higher thermal conductivity than the roller electrodes 21 and 22 are brought into contact with each other. In this state, the roller electrodes 21 and 22 and the holding members 31 and 41 can be connected and separated. Therefore, the holding members 31, 41 having a higher thermal conductivity than the roller electrodes 21, 22 are brought into contact with the roller electrodes 21, 22, in the radial direction center, so that the holding members 31, 41 can be separated from each other. it can.

  Further, in the first embodiment, the annular recess 22e is formed on the radially inner side of the roller electrodes 21 and 22. The area of the contact surface between the roller electrodes 21 and 22 and the holding members 31 and 41 can be increased by the annular concave portion 22e, and the heat of the roller electrodes 21 and 22 is transmitted to the holding members 31 and 41 having high thermal conductivity. It is possible to prevent cracks due to the thermal stress of the components 21 and 22.

  In the first embodiment, in a galvanized steel sheet seam welding apparatus 1 for seam-welding joining flange portions 101a and 102a of a fuel tank 100 made of press-formed galvanized steel sheet, outer peripheral surfaces 21a of roller electrodes 21 and 22 are provided. , 22a are provided on the outer peripheral portions 21b, 22b constituting both side surfaces, and the coating layers 23, 24 are cooled with cooling water from above, thereby enabling welding. Therefore, cooling water is sprayed from the outside of the coating layers 23 and 24 of the roller electrodes 21 and 22 to the roller electrodes 21 and 22 in contact with the joining flange portions 101a and 102a of the galvanized steel sheet. , 22 and the joining flange portions 101a, 102a can be cooled while preventing the roller electrodes 21, 22 from being corroded by cooling water, so that cooling efficiency can be improved and thermal deformation of the press-formed steel plate can be prevented.

  In the first embodiment, the cooling medium is used as the cooling water, and the cooling water is sprayed from both sides of the joining flange portions 101a and 102a of the galvanized steel sheet toward the welding position P where the electrode tip is located. The electrodes 21, 22 and the fuel tank 100, which is a steel plate, were simultaneously cooled. Accordingly, thermal deformation of the fuel tank 100, which is a press-formed steel plate, can be further prevented, and the cooling properties of the roller electrodes 21, 22 are further improved, so that the welding quality and the durability of the roller electrodes 21, 22 are improved.

  In the first embodiment, the contact surfaces of the roller electrodes 21 and 22 with which the vibrating tools 52 and 72 abut are reciprocated by vibrating the vibrating tools 52 and 72 along the electrode rotation direction of the roller electrodes 21 and 22. Was welded while dressing. Therefore, the vibrating cutting tools 52, 72 are vibrated to scrape off the outer peripheral surfaces 21a, 22a of the roller electrodes 21, 22, thereby removing the adhering matter adhering to the roller electrodes 21, 22 as a lump and the surface of the roller electrodes 21, 22. Smoothing can be performed efficiently, and welding quality can be further improved.

  In the first embodiment, the roller electrodes 21 and 22, the cooling water injection device 10, and the vibrating tools 52 and 72 are integrated with the base 20 of the welding unit 5. Therefore, the seam welding apparatus 1 for galvanized steel sheets can be made compact.

In the first embodiment, of the roller electrodes 21 and 22, one of the roller electrodes 21 has a plate thickness of t1 and the outer diameter is d1, and the other roller electrode 22 has a plate thickness of t2 and an outer diameter of d2. In this case, t1, d1, t2, and d2 are set so as to satisfy the relational expression t1 · d1 ^1/2 = t2 · d2 ^1/2 . Therefore, the current density balance is ensured, so that the current value width of seam welding can be widened and the welding quality is improved.

<Second embodiment>
FIG. 6 is a sectional view of the small roller electrode 122 according to the second embodiment of the present invention.
In the description of the second embodiment, the same components as those of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
In the second embodiment, a small roller electrode 122 and a pressing portion 143 are provided instead of the small roller electrode 22 and the pressing portion 43 of the holding member 41 in the first embodiment.
In the first embodiment, the concave portion 22e and the convex portion 42f are provided only on one side in the axial direction. However, on the inner peripheral side of the small roller electrode 122 in the second embodiment, the pressing portion 143 is also provided. An annular concave portion (annular concave portion) 122e is formed. The recess 122e is recessed in a direction to reduce the plate thickness t2 of the small roller electrode 122.
A disc-shaped projection 143f formed on the holding portion 144 fits into the recess 122e. The convex portion 143f fits into and contacts the concave portion 122e.

  In the second embodiment, concave portions 22e, 122e and convex portions 42f, 143f are provided on both sides in the axial direction, respectively, and the area of the contact surface between the small roller electrode 122 and the holding member 41 is further increased. Thus, cracking due to thermal stress of the electrode is easily prevented.

The above-described embodiments merely show one aspect of the present invention, and can be arbitrarily modified and applied without departing from the gist of the present invention.
The annular concave portions 22e and 122e and the annular convex portions of the small roller electrodes 22 and 122 may not be provided.
A configuration in which an annular convex portion is formed on the small roller electrodes 22 and 122 and an annular concave portion is provided on the holding members 41 and 141 may be employed.

Reference Signs List 5 welding unit 10 cooling medium injection means 20 base 21, 22 electrode body, roller electrode 21a, 22a outer peripheral edge, contact surface 21b, 22b flat outer peripheral surface, outer peripheral portion 21d, 22d mounting portion 22e, 122e annular concave portion 23, 24 Coating layer 31, 41 Conductive member 52, 72 Cutting means 101a, 102a Joining flange portion

Claims (9)

In a galvanized steel sheet welding electrode, seam welding is performed while cooling the joining flange portions (101a, 102a) of the galvanized steel sheet with a cooling medium .
The electrode body portions (21, 22) of the seam welding are made of a disk-shaped molybdenum or tungsten material, and at least both side surfaces on the outer peripheral edge (21a, 22a) side of the electrode body portions (21, 22) are flat outer peripheral surfaces. (21b, 22b), and a chromium or nickel-based coating layer (23, 24) on the plate-shaped outer peripheral surface (21b, 22b).   The electrode for welding galvanized steel sheets according to claim 1, wherein the coating layers (23, 24) are chromium films in which chromium is saturated with nitrogen.   A conductive member (31, 41) having a mounting portion (21d, 22d) at the radial center of the electrode body (21, 22) and having a higher thermal conductivity than the electrode body (21, 22). The welding of the galvanized steel sheet according to claim 1, wherein the electrode body (21, 22) and the conductive member (31, 41) can be joined and separated in a state where they are in contact with each other. Electrodes.   The galvanized steel sheet according to any one of claims 1 to 3, wherein an annular recess (22e, 122e) is formed on a radially inner side of the electrode body (21, 22). electrode. In a galvanized steel sheet seam welding apparatus for seam-welding the joining flange portions (101a, 102a) of a galvanized steel sheet formed by press forming,
Coating layers (23, 24) are provided on both sides of the outer peripheral portions (21b, 22b) of the roller electrodes (21, 22), and the coating layers (23, 24) can be welded by cooling with a cooling medium from above. A seam welding apparatus for galvanized steel sheets.   The cooling medium is used as cooling water, and cooling water is sprayed from both sides of the joint flange portions (101a, 102a) of the galvanized steel sheet toward the tip of the electrode to simultaneously cool the roller electrodes (21, 22) and the steel sheet. The seam welding apparatus for galvanized steel sheet according to claim 5, characterized in that:   The cutting means (52, 72) reciprocally oscillates along the electrode rotation direction of the roller electrodes (21, 22), and the contact surfaces (21, 22) of the roller electrodes (21, 22) with which the cutting means (52, 72) abut. 7. The seam welding apparatus for galvanized steel sheet according to claim 5, wherein welding is performed while dressing 21a, 22a). 8. The method according to claim 7 , wherein the roller electrodes, the cooling medium spraying means and the cutting means are integrated into a base of a welding unit. The described seam welding apparatus for galvanized steel sheet. When the thickness of one of the roller electrodes (21, 22) is t1, the outer diameter is d1, and the thickness of the other roller electrode (22) is t2, and the outer diameter is d2. The following relational expression t1 · d11 / 2 = t2 · d21 / 2
The seam welding apparatus for a galvanized steel sheet according to any one of claims 5 to 8, wherein t1, d1, t2, and d2 are set so as to satisfy the following.

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