JPH0679783B2 - Method and apparatus for butt resistance welding of thin plates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The disclosed technology belongs to the field of technology in which butt welding of thin steel plates having a plate width of 10 mm and a thickness of 0.1 mm is performed by resistance welding.

<Prior Art> As is well known, there are various modes of joining means by welding metals to each other.For example, when welding thin plates to each other, a step is formed in surface welding by superposition, etc. May not be suitable. For example, among steel belts used for continuously variable transmissions among automobile power transmission belts recently developed as a new technology, the plate width is 5 to 20.
mm, there is a plate thickness of about 0.1 ~ 0.3 mm, for such steel belt, there is a restriction that surface welding by overlapping of both ends can not be done, therefore, of course, butt welding must be performed, Moreover, considering the great tensile stress of the steel belt as a product during operation, the strength of the butt-welded portion needs to be considerably increased.

Thus, as described above, laser beam welding or electron beam welding can be applied to butt welding of thin plates having an extremely thin plate thickness compared to the plate width under special conditions such as the above size. Although welding joining is possible, since the seed welding joining is a kind of fusion welding, the solidified structure of the molten metal remains after the welding, and in order to satisfy the requirement of high strength such as the steel belt as described above. In the subsequent process, processing such as ring roll rolling and heat treatment process are required.

Therefore, even if it is possible to obtain a desired required strength in the production mode of only a single product, in the production mode of mass production, there are disadvantages that the man-hours are large and the production efficiency is low, and the blowhole is not produced. There was a defect in quality such as occurrence, and it was not possible to expect reproducibility with the same accuracy.

<Problems to be Solved by the Invention> On the other hand, it is conceivable to employ means for conducting a large current in a very short time by butt resistance welding and joining them instantaneously. If the plate thickness is extremely thin compared to the width, for example, even if the protrusion amount is 0.2 to 0.5 mm, buckling occurs at the butt end due to the high pressure applied initially for resistance welding, and butt resistance welding is performed. There was an inconvenience that it became impossible.

This means that, for example, as disclosed in the Japanese Patent Publication No. 56-53465, the molten metal in the butt resistance welding portion of the metal material after the welding current is conducted causes a plastic flow to the molten metal to cause a plastic flow. Even if an attempt is made to apply the technique of having no solidification composition, producing almost no welding distortion, having high reproducibility, and having good productivity, in the case of a thin plate with an extremely thin thickness, as described above, the initial application Since the load is large, buckling is unavoidable and there is a negative point that it cannot be actually applied.

The object of the invention of this application is to solve the problem of butt resistance welding of thin plates having an extremely thin plate thickness as compared with the plate width based on the above-mentioned conventional technique, and to solve molten metal generated in the initial stage of resistance welding. An excellent butt resistance welding of thin plates that utilizes the technique of instantaneous plastic flow and causes plastic flow by applying a load that follows the conduction current of the resistance welding, which is beneficial to the field of metal joining technology application in various machine manufacturing industries. It is intended to provide a method and a device used directly in the method.

<Means for Solving the Problem> The configuration of the invention of the present application, which has the above-mentioned claims as the gist along with the above-mentioned object, has a butt portion when performing butt resistance welding between thin plates in order to solve the above-mentioned problem. In the resistance welding method in which plastic flow is generated, resistance welding is performed by applying a current from a power source while conducting resistance welding by applying an initial butt load to the butt portion, and further applying in addition to the initial butt load. Applying a high-pressure applied load that approximates the welding current applied to the second stage, and applies a second-stage high-pressure butt load by an electromagnetic pressure device as a second-stage butt load applying device to generate plastic flow in the butt portion. The butt resistance welding method for thin plates is provided with a fixed clamp for each of the butt ends of the pair of thin plates and a movable clamp that is juxtaposed with the fixed clamp. The movable clamp is connected to the first-stage butt load applying device, and a high-voltage applied load that is provided between the first-stage butt load applying device and the movable clamp and that approximates a welding current applied thereto is applied. Technical means connected to the electromagnetic pressure applying device as the second-stage butt load applying device to be applied, and thus the fixed clamp, the movable clamp, and the electromagnetic pressure applying device are connected to the same power source. It was taken.

<Action> Thus, in the butt resistance welding of both ends of a thin plate having a plate thickness extremely smaller than the plate width, one end of the thin plate is supported by a fixed clamp and the other end is supported by a movable clamp, and the butt section first In the state where the initial load of the first step is applied, a predetermined large current for resistance welding is conducted to generate molten metal in a momentary extremely short time, and at the butt section by means such as electromagnetic pressure load. A high load is applied to the second stage, which approximates to the large current, to apply a large load in a superimposed manner to cause a plastic flow in the molten metal and to push the molten metal to the side near the abutting portion. Welding the thin plate ends, and the molten metal extruded laterally afterwards is removed by cutting, etc. Therefore, the butt resistance welding part has little welding distortion, the solidified composition of the molten metal does not remain, and a good welding is possible. As gained in strength In addition, during butt resistance welding, buckling or the like does not occur even though both ends have a short protrusion amount.

<Embodiment> Next, one embodiment of the invention of this application will be described below with reference to the drawings.

Reference numeral 1 denotes a butt resistance welding device for a thin plate 2, which constitutes one of the gist of the invention of this application. In the illustrated mode, as shown in FIG. 5, a steel belt of a continuously variable transmission of an automobile is used. It shows resistance welding of the abutting portion 3 of the thin plate 2 to be formed. The thin plate 2 has, for example, a plate width of 5 to 20 mm and a plate thickness of 0.1 to
It is a thin tape with a thickness of 0.3 mm.

Then, as shown in FIG. 4, a fixing clamp 5 for the thin plate 2 is provided on one side of the plate 4 provided on a base (not shown) so that the upper clamp 6 for tightening and fixing the thin plate 2 can be detached by bolts. The fixed clamp 5 is provided with a movable clamp 7 at its front end, and the movable clamp 7 has a slider 9 via a dovetail groove 8 as shown in detail in FIG. Is engaged slidably along the longitudinal direction of the plate 4, and its upper clamp
The thin plate 2 can be tightened between the slider 9 and the slider 9 by freely removing 10 with bolts.

Then, as shown in FIGS. 1 and 2, the thin plate 2 is arranged such that the fixed clamp 5 and the movable clamp 7 face each other in a loop shape with the abutting portion 3 facing downward as shown in FIG. It is designed to be tightly fixed.

Further, as shown in the drawing, the movable clamp 7 can be moved toward and away from the fixed clamp 5 by a slight distance via a slider 9 on the upper side thereof.

An electromagnetic pressure device 11 is provided so as to be separated from the fixed clamp 5 in the longitudinal direction by a set distance, and a fixed yoke 12 fixed to the plate 4 is provided on the opposite side of the fixed clamp 5 with an exciting portion 13. On the other hand, a movable yoke 14 is movably provided on the plate 4 between the fixed yoke 12 and the fixed clamp 5 via an appropriate roller, and the movable yoke 14 has a base end. The fixed wire 15 is inserted through the fixed yoke 12 and is engaged with the idle roller 17 of the roller device 16 which is erected at the other end of the plate 4 to extend and hang down, and the insertion hole 18 of the plate 4 is inserted. The weight is loosely inserted and the other end is connected to a weight 19 as a butt load applying device in the first stage to be in a tensioned state.

Further, with respect to the movable yoke 14, another wire 15 'is connected and fixed at the base end on the side opposite to the wire 15, and is loosely inserted into a guide hole 20 formed in the fixed clamp 5 in the longitudinal direction. As shown in FIG. 2, the slider 9 of the movable clamp 7 is inserted and the tip is connected and fixed to the rear end surface.

Therefore, the slider 9 of the movable clamp 7 is always biased by the initial load f so as to approach the fixed clamp 5 side by the weight 19 through the wires 15 and 15 'through the movable yoke 14. Therefore, as shown in FIG. 5, the butt portion 3 of the thin plate 2 is applied with the initial load f by the weight 19 simultaneously with the setting.

In this case, the protrusion amount at the abutting portion 3 of the thin plate 2 is 0.
It is extremely small, 2 to 0.5 mm, and is designed so that buckling or the like does not occur in the abutting portion 3 due to the initial load f by the weight 19.

Further, in the butt resistance welding apparatus 1, the transformer 21 attached for the electric system of the butt resistance welding has the lead wire.
The fixed clamp 5, the movable clamp 7, and the exciting coil 23 of the fixed yoke 13 of the electromagnetic pressure device 11 are electrically connected via 22. Therefore, when a welding current is applied to the circuit, the fixed clamp 5, A welding current is applied to the protruding portion of the butt portion 3 of the thin plate 2 via the movable clamp 7, and the fixed yoke 12 of the electromagnetic pressing device 11 is excited to move the movable yoke.
The magnetic force that attracts 14 acts, and therefore the fixed clamp 5
To the slider 9 of the movable clamp 7 against the
In addition to the initial load f of the first stage due to 19, the second stage load of electromagnetic pressure is further applied. This state is shown in FIG. 7 (the horizontal axis is time t, the vertical axis is The current i
As shown by the loads f and F in the lower stage, the welding current i conducted so that the electromagnetic pressure load F in the second stage is applied to the initial load f by the weight 19 in the first stage. Has been

In the above structure, the thin plate 2 is clamped to the fixed clamp 5 and the slider 9 of the movable clamp 7 via the upper clamps 6 and 10, respectively, and the abutting portion 3 thereof is projected by 0.2.
Clamping is performed to 0.5 mm, and in FIG. 7, at time t on the horizontal axis, the weight 19 is hung at the tip of the wire 15 at time t _{1 to} prevent buckling of the butted portion 3 in the first step. The initial load f is applied and set.

Then, the At a Figure 7, from t ₂ to close the t ₂ at circuit
Short time of t ₃ , for example 1 to 3kA during 4 to 8mm seconds
A large current resistance welding current i of / mm ² is conducted, and the butt resistance welding is performed on the butt portion 3 of the thin plate 2.

Thus, as shown in FIG. 7, while the butt resistance welding of the butt portion 3 is being performed, the fixed yoke 13 of the electromagnetic pressure device 11 is also excited by the coil 23.
On the other hand, the second-stage electromagnetic pressure load F is applied, and a large electromagnetic pressure load F of 25 to 60 kg / mm ² is instantaneously applied to the molten metal of the butt section 3.

Therefore, as shown in FIG. 6, in the butt portion 3, plastic flow of the molten metal is generated through heating by the welding current, and the molten metal is extruded to the side portion of the butt portion 3, and the residual composition of the molten metal such as oxide is left. Minutes will be pushed to the side.

Since the electromagnetic pressure load F is applied instantaneously and in addition to the second stage load, only the molten metal plastically flows and is pushed out to the side.

When the welding current i which is conductive to t ₄ during circuit disappears blocked, as shown in FIG. 7, the second stage of the electromagnetic pressure load F that is applied to the butt portion 3 of the weld Disappears following this, and only the same load f as the initial load f of the first stage by the weight 19 is applied.

Then, the initial load f assists the curing of the weld metal of the butt portion 3.

Therefore, the joining surface of the abutting portion 3 is expanded by the application of the electromagnetic pressure load F in the second stage, and the temperature distribution is averaged accordingly, the joining surface becomes flat, and plastic flow largely works, resulting in Therefore, high welding strength can be obtained.

Then, when t ₅ at butt resistance welding is completed, the wait
19 is removed from the wire 15, the fixed clamp 5 and the movable clamp 7 are disengaged, and the loop-shaped thin plate 2 to which the butt portion 3 is welded and joined is removed, and the butt portion 3 is extruded by plastic flow and protrudes. The molten metal present is removed by an appropriate forming means such as a grinder to obtain a loop-shaped steel belt having the same cross section on the entire surface.

In the above-described embodiment, the electromagnetic pressurizing device is used as the second-stage high-pressure butt load applying device, but in the present embodiment, the second-stage high-pressure butt load is applied in accordance with welding current conduction. It is used because the response characteristics of the case is very good, but as far as the response characteristics of the second-stage high-pressure butt load applying device, or means, are approximated in accordance with the welding current to be conducted. Various modes such as using mechanical means can be adopted.

<Effects of the Invention> As described above, according to the invention of this application, a thin plate having an extremely small thickness as compared with a plate width of a steel belt or the like for power transmission, which is basically installed in a continuously variable transmission of an automobile or the like. In the butt resistance welding of, the butt resistance welding, which is originally excellent, is prevented, but the buckling at the butt portion is prevented, and the welding strength can be increased without generating the residual structure of the molten metal. High precision reproducibility is ensured, and moreover, mass productivity can be improved and work efficiency can be improved.

In addition, a large amount of plastic flow can be generated in the vicinity of the joint surface of the butt portion, so that the temperature distribution of the joint surface is made uniform, the solidified structure does not remain, and the surface shape of the joint surface of the thin plate is also affected. The excellent effect of being able to perform sound welding with less welding distortion is exhibited.

Thus, by applying the first stage initial butt load to the butt portion, and simultaneously applying the high pressure butt load of the second stage during butt resistance welding, that is, during welding current application, following the current. , Molten metal is formed in the abutting portion, buckling does not occur, only the molten metal can be plastically flowed and pushed out to the side, and therefore, even if the thin plate has a significantly small thickness compared to its width, The solidified structure of the molten metal does not remain without welding distortion, and it is possible to obtain uniform and accurate sound butt welding.

In addition, when applying a high-pressure butt load at the second stage, by using an electromagnetic pressurizing device, it is possible to specially perform a large high-voltage butt load application and welding current energization in the butt resistance welding in accordance with the large current applied. The excellent effect that the current can be controlled synchronously with the same current without using the synchronous circuit of No. 1 is therefore provided. Therefore, it is not possible to apply a large load only to the initial load to cause buckling. Instead, only the molten metal is plastically flowed by the large load applied in the second stage and pushed out to the side, and the excellent effect that the above-described highly accurate welded joint can be obtained is exhibited.

[Brief description of drawings]

The drawings are explanatory views of one embodiment of the invention of this application.
The figure is an overall schematic plan view of the apparatus, FIG. 2 is a longitudinal sectional view of the same, FIGS. 3 and 4 are transverse sectional views of III-III and IV-IV of FIG. 2, and FIG. FIG. 6 is a plan view of the molten metal plastic flow state of the butted portion of the thin plate, and FIG. 7 is a graph showing the relationship between the applied current and the applied load to the butted portion of the thin plate. 2 ... Thin plate, 3 ... Butting part, f ... Initial butting applied load, F ... Second-stage high-pressure butting load, 1 ... Butt resistance welding device, 5 ... Fixed clamp, 7 ... Movable clamp , 11 …… Electromagnetic pressure device (second stage butt load applying device), 19 …… Weight (first stage butt load applying device)

Claims (2)

[Claims] 1. A method of resistance welding by causing plastic flow in a butt portion when performing butt resistance welding of thin plates to each other, wherein a resistance welding is performed by energizing the butt portion while applying an initial butt load. The second stage by the electromagnetic pressurizing device as the second stage butt load applying device that performs resistance welding with the current of the second stage and applies the high-pressure applied load that is approximated by the welding current applied in addition to the initial butt load A butt resistance welding method for thin plates, characterized in that a high-pressure butt load is applied to cause plastic flow in the butt portion. 2. An apparatus used for butt resistance welding of thin plates, wherein a fixed clamp for each of the butt ends of a pair of thin plates and a movable clamp juxtaposed with the fixed clamp are provided, and the movable clamp is a first stage butt. A second stage butt load applying device that is connected to the load applying device and is provided between the first stage butt load applying device and the movable clamp to apply a high voltage applied load that approximates the welding current applied. A butt resistance welding apparatus for thin plates, wherein the fixed clamp, the movable clamp and the electromagnetic pressure applying apparatus are connected to the same power source.