JPH0688142B2 - Resistance welding method and apparatus - Google Patents

Description

TECHNICAL FIELD The present invention relates to a resistance welding method and apparatus relating to electric resistance welding.

[Conventional technology]

In electric resistance welding such as spot welding, a pair of upper and lower electrodes facing each other is used to press an object to be welded, and welding is performed by applying an electric current for a predetermined time, which is widely used. In this case, the second
As shown in the figure, the electrode chips 1 and 2 may be fixed directly to the electrode holders 5 and 6, or may be fixed to the electrode holders via shanks (also called sleeves) 3 and 4. 5,6 are used by being fixed to arms (or horns) 7,8. In this case, generally, the electrode pressing shaft 9 is often the same as the central axis of the electrode. Here, the part composed of the electrode tip, the shank and the electrode holder is referred to as an electrode part,
A portion composed of the electrode portion and the arm will be referred to as an electrode peripheral portion.

When welding with the structure of the electrode peripheral part as shown in FIG. 2, if the material to be welded is a general cold-rolled steel plate, it shows sufficient continuous spotting property (electrode life), but various surfaces including galvanized steel plate In the welding of the treated steel sheet, the electrode tip made of a copper-based material and the plated metal of the steel sheet are alloyed with increase in the number of hit points, and the electrode tip portion (contact portion with the steel sheet) is worn and expanded.
For this reason, the current density is lowered, a predetermined nugget is not formed, and the time (number of dots) until the dressing or replacement of the electrode tip has to be shortened, so that the productivity is inevitably lowered.

As means for solving these difficulties, for example, Japanese Patent Laid-Open No. 61-29
Although 3679 and Japanese Utility Model Laid-Open No. 61-67978 are known, in the case of this device, an electrode rotating shaft is provided in the direction perpendicular to the electrode pressing shaft, and a plurality of electrode chips are provided around this rotating shaft. Welding is carried out by embedding or attaching a ring-shaped electrode and rotating it intermittently, but these are large in terms of equipment, and due to their structure, the shape of the work piece is considerably restricted. There was a drawback.

[Problems to be Solved by the Invention]

An object of the present invention is to solve the problems of the conventional welding method and apparatus, and it is an object of the present invention to provide a resistance welding method and apparatus having a high continuous spotting property in the welding of plated steel sheets.

[Means for Solving the Problems]

 The gist of the present invention is listed below.

(1) In the resistance spot welding method, both or one of the pair of electrode holders facing each other is tilted with respect to the pressure axis, and the tip of the electrode tip provided on the electrode holder is used as a workpiece. After contacting and energizing and welding spots at a desired frequency, while tilting the central axis of the tilting arm in a plane formed by the central axis of the tilting arm on which the electrode holder is mounted and the pressure axis, By tilting the central axis of the tilting arm in a direction perpendicular to the plane passing through the central axis of the electrode, and thus intermittently tilting the tip end portion of the electrode tip with respect to the pressing axis by a predetermined angle at a time. , A resistance welding method characterized by performing welding on a contact surface at each angle.

(2) In a resistance spot welding apparatus including an electrode tip and an electrode holder on both or one of opposing electrode portions, the electrode holder is mounted on a tilting arm, and is formed by a central axis of the tilting arm and a pressure axis. The electrode peripheral device is provided with a mechanism for tilting the central axis of the tilting arm in a plane and a mechanism for tilting the central axis of the tilting arm in a direction perpendicular to the plane through the electrode central axis of the electrode holder. Resistance welding equipment.

(3) The device according to (2), wherein the tilting arm has a cylindrical shape and is connected to the arm by a spherical bearing.

(4) The device according to (2), wherein the tilting arm has a link ball shape and is connected to the arm by a spherical bearing.

(5) The device according to (2), (3) or (4), wherein a link ball and a spherical bearing are provided at one end of the electrode holder, and a mechanism for moving the link ball and the spherical bearing in a predetermined direction is provided.

The present invention will be described below with reference to the drawings.

[Action]

1 (a) and 1 (b) show an embodiment of the present invention. In FIG. 1 (a), the upper and lower electrode chips 1 and 2 fixed to the upper and lower tilting arms 10 and 11 and the electrode center shafts 12 and 13 of the electrode holders 5 and 6 are connected to the electrode pressing shaft 9 against the workpiece S. On the other hand, in the plane formed by the tilting arm central shafts 16 and 17 and the electrode pressing shaft 9, they are intermittently tilted (inclined) by a predetermined angle θ in the directions of arrows A and B. In this case, one is + (plus)
If it is on the other side, the other side is also set to the + (plus) side and the electrode tips are always opposed. As a method thereof, for example, the central axes 16 and 17 of the tilting arms 10 and 11 are tilted by a predetermined angle θ so that the upper and lower electrode portions face each other with points Q1 and Q2 on the central axes 14 and 15 of the upper and lower arms serving as fulcrums. In FIG. 1 (b), the center axes 12, 13 of the upper and lower electrode chips 1, 2 and the electrode holders 5, 6 fixed to the upper and lower tilting arms 10, 11 are the center axes of the electrodes with respect to the pressure axis 9.
Go through 12, 13 in the direction perpendicular to the plane, ie the arrow
Tilt by a predetermined angle ψ intermittently as in the C and D directions.
In this case, if one is on the + (plus) side, the other is also on the + (plus) side, and the electrode tips are always opposed to each other. The fulcrum of tilting is not necessarily limited to the center axis of the arm or the center axis of the electrode holder and its intersection,
Other positions are also acceptable.

3 (a) and 3 (b) show specific embodiments of the electrode peripheral portion having the tilting function of the present invention with respect to the upper electrode peripheral portion.

FIG. 3A shows a side view of the peripheral portion of the upper electrode. The electrode chip 1 is fixed to the electrode holder 5, and the electrode holder is fixed to the tilting arm 10. The tilting arm 10 is connected to the fixed arm 7 via a spherical bearing 18 in a slidable manner and in a state where sufficient electric conductivity can be secured. The central axis 12 of the electrode holder fixed to the tilting arm 10 is intermittently tilted with respect to the pressing shaft 9 by a predetermined angle θ in a plane formed by the tilting arm central shaft 16 and the electrode pressing shaft 9. For this purpose, the link ball 19 and the spherical bearing 20 provided on the electrode holder 5 are moved in the direction of arrow E by a predetermined amount by a cam mechanism or the like, and stopped and fixed at that position. As a result, with the fulcrum Q on the central axis 14 of the fixed arm 7 as the fulcrum of tilting, the central axis 16 of the tilting arm 10 tilts by an angle θ, and the electrode central axis 12 also tilts by an angle θ and stops.

FIG. 3 (b) shows a front view of the periphery of the upper electrode. In order to intermittently tilt (tilt) the electrode center shaft 12 with respect to the pressing shaft 9 by a predetermined angle ψ, the electrode holder 5 is provided. The provided link ball 19 and spherical bearing 20 are moved in the direction of arrow F by a predetermined amount by a cam mechanism or the like, and stopped and fixed at that position. As a result, with the fulcrum Q as the fulcrum of tilting, the electrode center axis 12 passes through the electrode center axis 12 and intermittently tilts by an angle ψ in the direction perpendicular to the plane and stops.

The mechanism for tilting the electrode center axis may be any other than the mode shown in FIGS. 3 (a) and 3 (b). For example, as shown in FIG.
Is fixed to the link ball 21 disposed in the arm 7, and the link ball is slidably connected to the spherical bearing 22 disposed in the arm 7 in a state where sufficient electric conductivity can be secured. The mechanism for tilting the electrode central axis 12 with respect to the pressure axis 9 by the angle θ (or the angle ψ) is as described in detail in FIG. 3, but the feature of this device is the fulcrum that tilts the central axis 12 of the electrode. Q is the arm center axis 7
And the central axis 12 of the electrode.

In this case, although not shown, the driving source for moving the spherical bearing 20 connected to the link ball 19 as shown by the arrow E (and F) is a motor, an air cylinder, or the like.
Well-known ones such as utilizing the vertical movement of the electrode may be used, and the driving force transmission means is a cam mechanism, a link mechanism, or another rack.
Known methods such as gears such as pinions, chains, and belts may be used. The tilting mechanism may be a means other than the exemplified method. For example, in the tilting angle θ direction,
A pinion, a cam mechanism, a link mechanism or the like may be used, and a worm gear, a bevel gear or the like may be used for the tilt angle ψ direction.

The tilting of the electrode holder is not performed at least when the electrodes sandwich the object to be welded, but is performed in a state where the electrodes are separated from each other. Further, the tilting fulcrum is illustrated on the center axis of the arm in FIGS. 3A and 3B and at the intersection of the center axis of the arm and the center axis of the electrode in FIG. The present invention is not limited to these, and may be at other locations.

With the configuration and method of the electrode peripheral portion as described above, the object to be welded is sandwiched between the upper and lower electrode tips, pressed, and energized for a predetermined time to perform welding.

FIGS. 5 (a), (b) and (c) show the method detailed in FIG. 1 of the present invention by welding with the apparatus detailed in FIGS. 3 (a) and (b) or FIG. The top view of the front-end | tip part of an electrode tip at the time of carrying out is shown. When the electrode portion is tilted by the angle θ as shown in FIG. 3 (a), the contact surface with the object to be welded formed on the electrode tip tip portion 23 as shown in FIG. It is formed on the X-axis centering on the center point P ₀ of the chip surface. On the other hand, when the electrode portion is tilted by the angle ψ as shown in FIG. 3 (b), the electrode tip tip portion 23 as shown in FIG. 5 (b).
The contact surface with the object to be welded is formed on the Y axis with the center point P ₀ of the electrode tip surface as the center. When these operations are combined, the contact surface with the object to be welded formed at the electrode tip tip 23 as shown in FIG. 5 (c) is XY centered on the center point P ₀ of the electrode tip surface. It is distributed as a combination. By repeating this operation, the tip surface of the electrode tip is evenly used for welding.

The degree of tilt of the electrode holder depends on the mechanism used, but the tilt angle θ is ± 0 degrees to 45 degrees, and the tilt angle ψ is ± 0 degrees.
It can be set freely within the range of 60 degrees. Among these, the proper tilt angle θ is in the range of ± 0 degrees to 30 degrees, and the tilt angle ψ is also ± 0 degrees.
It is in the range of 30 degrees. Here, the tilting angle of 0 degree means that the electrode center axis may be vertical in the middle of tilting the electrode portion in all directions. The frequency of tilting the electrode can be freely set within the range of once / point to once / thousands of points, but the proper tilting frequency is 1 / point to 1/5.
The range is 00 points.

Further, although an example of the spot welding machine including a pair of electrodes facing each other has been described in FIG. 1, the applicable welding machine is not limited to this. For example, when the electrode 24 on one side as shown in FIG. 6 has a flat shape, only one electrode needs to be tilted, and a welding machine is a series spot welding machine.
It can be applied to a wide range such as multi-spot welders and portable spot welders.

In the conventional welding method, since the welding is performed at the electrode contact surface at a certain position, the contact area is expanded and the current density is reduced with an increase in the number of hit points, and finally a predetermined nugget is not formed,
According to the method of the present invention and the apparatus therefor, it is possible to perform welding without any difference from the conventional welding work by using a normal electrode tip, and moreover, the contact surface with the object to be welded is alloyed with the plated metal of the steel sheet and the area is slightly different Even if it is expanded, the contact area moves one after another for each preset number of dots, and the new contact surface deforms (shapes) the previous contact surface. Since it hardly expands, the decrease in current density is small and the number of continuous dots (electrode life) is significantly improved.

As described above, the method and apparatus for intermittently tilting the electrode holder play a very important role in improving the continuous hitting property.

[Embodiment] An embodiment relating to the continuous welding property of the spot welding method and apparatus according to the present invention will be described below.

The material to be welded is hot-dip galvanized steel sheet with a thickness (t) of 0.8 mm 150/1
Two sheets of 50 (g / m ² ) were used. The welding conditions are summarized below.

・ Welding machine: Stationary spot welding machine 60kvA ・ Electrode shape: Radius type (8R) / Cap tip ・ Pressure force: 200kg ・ Electrification time: 10 cycles ・ Welding current: Scattering limit current value (10300 ± 500A) ・ Spot pitch : 15mm ・ Spotting speed: 1 point./2 seconds The continuous spotting property is evaluated by collecting 100 points for each nugget diameter measurement test piece. Is the maximum number of welding points before it can no longer be secured. Table 1 shows the detailed welding conditions and continuous dot evaluation results of the present invention in comparison with the conventional method.

[Effects of the Invention] As is clear from the results shown in Table 1 above, the resistance welding method and apparatus thereof according to the present invention is applied to resistance welding of various surface-treated steel plates including plated steel plates, and the welding target Although there is no electrode welding to the object and some auxiliary equipment is required around the electrode part, it can be welded without any change from conventional welding work, and the electrode wear due to the increase in the number of dots Since it is shaped, it can form a nugget of a certain size, and the number of continuous welding points increases remarkably compared to the conventional welding method, so that it can bring about a great effect on industrial use such as improvement in production efficiency. .

[Brief description of drawings]

1 (a) is a side view of an electrode peripheral portion showing an aspect of the method of the present invention, FIG. 1 (b) is a front view of the same, FIG. 2 is a side view showing an aspect of a conventional electrode portion peripheral device, FIG. 3 (a) is a side view showing a tilting mechanism portion around the upper electrode of the device of the present invention,
3 (b) is a front view thereof, FIG. 4 is a side view showing a tilting mechanism portion around the upper electrode of the device of the present invention, FIG. 5 (a),
(B) and (c) are plan views of an electrode tip portion showing an embodiment of the present invention, and FIG. 6 is a side view showing an embodiment when one of the present invention is a flat electrode. 1,2 ... Electrode tip, 3,4 ... Shank, 5,6 ... Electrode holder, 7,8 ... Arm, 9 ... Pressurizing shaft, 10, 11 ... Tilt arm, 1
2,13… electrode center axis, 14,15… (fixed) arm center axis, 16,
17 ... Tilt arm central axis, 18 ... Spherical bearing, 19 ... Link ball, 20 ... Spherical bearing, 21 ... Link ball, 22 ... Spherical bearing, 23 ... Electrode tip surface, 24 ... Flat electrode, A, B ... Electrode part Tilting method, C, D ... tilting direction of electrode part, E ... moving direction of spherical bearing, F ... moving direction of spherical bearing.

Claims (5)

[Claims] 1. In a resistance spot welding method, both or one of a pair of electrode holders facing each other is tilted with respect to a pressure axis, and the tip of an electrode tip provided on the electrode holder is welded. After making contact with an object and energizing it and welding spots at a desired frequency, while tilting the central axis of the tilting arm in a plane formed by the central axis of the tilting arm on which the electrode holder is mounted and the pressure axis, , The tilting arm is tilted in a direction perpendicular to the plane through the electrode central axis, and thus the tip end portion of the electrode tip is intermittently tilted by a predetermined angle with respect to the pressing axis, A resistance welding method characterized by performing welding on a contact surface at each angle. 2. A resistance spot welding apparatus including an electrode tip and an electrode holder on both or one of opposing electrode parts, wherein the electrode holder is mounted on a tilting arm, and a center axis of the tilting arm and a pressing shaft are provided. The electrode peripheral device is provided with a mechanism for tilting the central axis of the tilting arm within a plane to be formed and a mechanism for tilting the central axis of the tilting arm in a direction perpendicular to the plane through the electrode central axis of the electrode holder. A resistance welding device characterized in that 3. The resistance welding apparatus according to claim 2, wherein the tilting arm has a cylindrical shape and is connected to the arm by a spherical bearing. 4. The tilting arm has a link ball shape and is connected to the arm by a spherical bearing.
The resistance welding device described. 5. The resistance welding apparatus according to claim 2, wherein a link ball and a spherical bearing are provided at one end of the electrode holder, and a mechanism for moving the link ball and the spherical bearing in a predetermined direction is provided.