JP2000107867A - Resistance welding equipment and welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the precision of an object to be welded without making it a die set structure by supporting a second object to be welded with a support mechanism, floating the support mechanism from a base with a spring, supporting a first object to be welded with a welding electrode, driving the support mechanism in the XY direction to align the cores of the first/second objects to be welded and conducting resistance welding. SOLUTION: A first object 3 to be welded is inserted into a longitudinal cavity of a first welding electrode 1 and is held. The first object 3 to be welded is preferably positioned by a first positioning member extending from an opening hole of the welding electrode 1 to the longitudinal cavity and a second positioning member forwarding and backwarding. A second object 4 to be welded is placed on a support table 5 and is held by collect chuck mechanism 6. By aligning the cores of the first/second objects 2, 3 and descending the first welding electrode 1, the first/second objects are resistance-welded. When the temp. of a weld zone is lowered to the transformation temp., tempering is conducted by causing a single pulse current to flow and thereafter, the pressing force of the first welding electrode 1 is released.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance welding apparatus suitable for resistance welding two workpieces, particularly indirect welding of a rotor and a shaft of an automobile engine.

[0002]

2. Description of the Related Art As an example describing a resistance welding electrode structure for indirect welding of a rotor and a shaft,
There is JP-A-3-57570. This is characterized by the fact that the welding electrode has a die set structure to increase the coaxiality of the rotor with respect to the shaft.By moving the welding electrode for the shaft up and down along the guide post, the deflection of the welding electrode from side to side is reduced. It could be very small, thus increasing the coaxiality of the shaft and the rotor supported on each of the welding electrodes.

[0003]

However, in a resistance welding apparatus having an indirect welding method and a welding electrode having a die set structure, a mechanism for applying a pressing force from both above and below during welding is required. Then, in order for the mechanism for applying the pressing force from below to receive the pressing force from above in a stable manner, it is necessary that the mechanism apply a pressing force that is approximately twice the pressing force from above. For example, if the applied pressure from above during welding is about 3 tons, the applied pressure from below must be about 6 tons, which requires a very large pressurizing mechanism, which increases the size of the equipment. In addition, there is a disadvantage that the cost is high.

Accordingly, the present invention provides a resistance welding apparatus and method for performing welding without applying a pressing force from below while maintaining coaxial accuracy between workpieces without using a welding electrode in a die set structure. Main purpose.

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems, in the first invention, a rod-shaped first workpiece and a second workpiece, which are longer in diameter than each other, are resistance-welded. A base member having mechanical strength capable of withstanding the pressure applied during welding, a positioning mechanism movable in the X direction and the Y direction, and a second member capable of supporting the first workpiece. A welding electrode, a bearing mechanism for selectively supporting the second workpiece and coupled to the positioning mechanism via a linear guide mechanism, and a welding surface of the second workpiece. A second welding electrode capable of selectively applying a pressing force to the base member and the supporting mechanism provided between the positioning mechanism and the supporting mechanism. Floating from the member, allowing the support mechanism to move up and down Further comprising a spring mechanism that provides a resistance welding apparatus according to claim.

In order to solve the above-mentioned problems, in the second invention, a welding current is passed between a rod-shaped first workpiece and a second workpiece, each of which has a rod shape longer than the diameter, and a resistance is applied. In a resistance welding apparatus having a first welding electrode and a second welding electrode for performing welding, positioning in which the first workpiece is gripped and positioned halfway in a longitudinal direction of the first welding electrode. A first positioning member extending from an opening in the middle of the first welding electrode to a set position in the longitudinal cavity, and a positioning mechanism in the middle of a longitudinal wall of the first welding electrode. A second positioning member for positioning by moving forward and backward through the provided opening and selectively gripping the rod-shaped first workpiece in cooperation with the first positioning member. To provide a resistance welding apparatus characterized in that: .

[0007] To solve the above-mentioned problems, a third
According to the invention, in the resistance welding method of performing a resistance welding by flowing a welding current between a first workpiece and a second workpiece in a rod shape longer than the diameter, At least the first welding electrode holds the pressing force applied to the workpiece even in a state where the welding current is substantially zero, and the welding portion between the first workpiece and the second workpiece is held. A resistance welding method, characterized in that when a temperature drops to about a transformation point, a single pulsed current is passed to perform tempering, and then the pressing force of the first welding electrode is released.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an embodiment of the resistance welding apparatus according to the present invention will be described with reference to FIGS. In FIGS. 1 and 2, a first welding electrode 1 has a longitudinal cavity 1a that can be received except for a tip portion of a first workpiece 2 such as a shaft, and supplies a welding current. A pressing mechanism (not shown) applies a downward pressing force during welding.

A positioning mechanism 2 is disposed in the longitudinal direction of the first welding electrode 1. Positioning mechanism 2
It is provided so as to move together with the first welding electrode 1,
A fixed positioning member 2a fixed in the middle of the first welding electrode 1 and extending into the longitudinal cavity 1a, and an opening 1b provided in the middle of the longitudinal wall of the first welding electrode 1 advances and retreats to a rod-like shape. The movable positioning member 2b for selectively positioning the first workpiece 1 in cooperation with the fixed positioning member 2a
Consists of

The distal end of the fixed positioning member 2 a has a V-shaped groove 2 a 1 so as to abut at two points a rod-shaped first workpiece 2 inserted into the longitudinal cavity 1 a of the first welding electrode 1. Have. The movable positioning member 2b is, for example, a cylinder device, and a cylindrical member 2b3 having a diameter larger than that of the cylinder rod 2b2 extending from the cylinder body 2b1 and moving forward and backward is attached to the distal end side of the cylinder rod 2b2. 2b
3 and the V-shaped groove 2a1 of the fixed positioning member 2a, the rod-shaped first workpiece 3 can be gripped.

The first workpiece 3 is, for example, a shaft of a turbine of an automobile engine, and the tip of the first workpiece 3 is a large-diameter portion 3 a having a diameter larger than the diameter of the longitudinal cavity 1 a of the first welding electrode 1. Until the upper end surface of the large diameter portion contacts the flat lower end surface of the first welding electrode 1.
1 is inserted into one longitudinal cavity 1a.

A second workpiece 4 such as a rotor to be welded to the first workpiece 3 has a welding surface 4 a larger than the welding surface of the first workpiece 3, Is formed with an annular projection 4b acting as a projection.
Then, the second workpiece 4 is selectively gripped and released by the collet chuck mechanism 6 on the support base 5. The collet chuck mechanism 6 is a normal one, and the center stationary member 6a
And a collet chuck nail that performs an expanding / contracting operation by performing a motion in an oblique direction (in the direction of the arrow) within a certain angle range to selectively grip and release the second workpiece 4.
6b and a tightening and releasing member 6c for operating the collet chuck claw 6b in such a manner.

The second welding electrode 7 has two electrode portions 7a,
7b, and can be moved in the left-right direction, the up-down direction, or the oblique direction by a driving device (not shown). At the time of welding, the lower flat surfaces of the two electrode portions 7a and 7b apply a pressing force to the welding surface 4a of the second workpiece 4 and the respective front end surfaces 7a1 and 7b1 face each other with a slight gap therebetween. An imaginary hole having a diameter somewhat larger than the diameter of the large-diameter portion 3a is defined so as not to contact the large-diameter portion 3a of one workpiece 3.

Normally, the base member 6a of the collet chuck mechanism 6 is made of a metal material, and is therefore installed on a support 9 via an insulating plate 8 made of an electrically insulating material. It is designed to prevent it from flowing. The support base 9 is supported by a columnar column member 10, and an inner ring (not shown) of a linear motion bearing member 11 is fixed to an outer surface of the column member 10 as a linear motion guide mechanism. 11 outer rings (not shown)
It is fixed to a part of the X, Y direction drive mechanism 12.

A spring member 13 is disposed so as to surround the outer wall of the linear motion guide mechanism 11 or the support member 10. The spring member 13 is located between the lower surface of the support 9 and a part of the X, Y direction drive mechanism 12. , The second workpiece 4, the collet chuck mechanism 6, the support member 10, etc., have an elastic force that overcomes the sum of the weights. Therefore, the receiving table 14 fixed to the lower end of the column member 10 is configured to float from the upper surface of the base mechanism 15 when no pressing force is applied. The linear motion guide mechanism 11 functions to help the up and down movement of the support member 10 be performed smoothly.

The X, Y direction driving mechanism 12 includes an X direction driving member 12A installed on the upper surface of the base mechanism 15, and a receiving member 12B provided thereon and moving together with the X direction driving member 12A.
And placed on the receiving member 12B, and X
Y-direction drive member 12C that moves in the Y direction perpendicular to the direction
And an operation / drive mechanism 12D for manually or automatically driving these drive members. X direction drive member 12
A is the X-direction rail 12A1 laid on the upper surface of the base mechanism 15.
And an X-direction slider member 12A2 that slides on the X-direction rail 12A1. Similarly, the Y-direction drive member 12C includes a Y-direction rail 12C1 extending in the Y-direction and a Y-direction slider member 12C2 sliding on the Y-direction rail 12C1.

Accordingly, when the pressing force is not received as described above, the support member 10 and the receiving base 14 thereunder float above the upper surface of the base mechanism 15, and the lower surface of the support base 9 is moved to the Y-direction slider member 12C2. Is separated from the upper surface of the support member 10 and the second workpiece 4 supported by the support member 10.
Can be easily moved in the X direction or the Y direction by the X, Y direction driving mechanism 12.

In the case of manual operation, the operation and drive mechanism 12D is a normal one that drives the X-direction drive member 12A and the Y-direction drive member 12C by turning the handle (not shown) in each of the X and Y directions. It is. In the case where the drive is performed automatically, an image processing device (not shown) optically sets equally spaced points on the circumference of the second workpiece 4 to, for example, 12 points (30 ° intervals). Or 18 points (20 ° intervals)
To obtain a virtual average center point, and by driving the servomotor so that the center point of the first workpiece 3 matches the average center point, high-accuracy positioning is automatically performed. I can do it.

FIG. 3 shows a simple welding circuit of this resistance welding apparatus. Re is a power control type rectifier circuit that converts AC power from an AC power supply PS into controlled DC power. Generally, a thyristor and a diode are used. It consists of a combination of circuit configurations. A plurality of capacitors C are connected in parallel depending on the required capacity, and are charged with DC power from the rectifier circuit Re. Most of the energy charged in the capacitor C is discharged in a very short time through the welding transformer T by closing the discharge control type switch SW, and is discharged through the first and second workpieces W1 and W2. A large current flows between the first and second welding electrodes E1 and E2. Here, the first and second workpieces W1 and W2 respectively correspond to the workpieces 3 and 4 in FIGS. 1 and 2, and the first and second welding electrodes E1 and E2 correspond to the welding electrodes 1 and 7, respectively. Corresponding.

Next, the operation at the time of welding will be described. First, the first welding electrode 1 has risen to the upper limit,
The two electrode portions 7a and 7b of the second welding electrode 7 move rightward and leftward to the set positions, respectively, and stand still. Further, the collet chuck claw 6b is also in an open state, that is, in an expanded state.

In such a stationary state, the first workpiece 3 is inserted into the longitudinal cavity 1 a of the first welding electrode 1,
When the upper end surface of the large diameter portion 3a comes into contact with the lower end surface of the first welding electrode 1, the positioning mechanism 2 is operated to move the movable positioning member 2b forward, and as shown in the drawing, the fixed positioning member 2a
Cooperates with to grip the first workpiece 3 and maintain the positioning state. At this time, when the first welding electrode 1 cannot be inserted smoothly due to the obstruction of the fixed positioning member 2a, the lower surface of the fixed positioning member 2a may be an inclined surface. On the other hand, the second workpiece 4 is placed on the support base 5 and the collet chuck mechanism 6 is operated to grip the second workpiece 4 with the collet chuck claws 6b as shown.

In this state, as described above, the receiving base 14 fixed to the lower surface of the column member 10 by the repulsive force of the spring member 13 is separated from the upper surface of the base mechanism 15, and the lower surface of the supporting table 9 is moved in the Y direction. It is separated from the upper surface of the slider member 12C2. In this state, the operation and drive mechanism 12D is operated,
The column member 10 is moved in the X and Y directions by driving the X, Y direction drive mechanism 12 so that the center point of the second workpiece 4 coincides with the center point of the first workpiece 3. The X, Y direction drive mechanism 12 is stopped at the coincided position and latched so as not to move.

Thereafter, the first welding electrode 1 is lowered while the movable positioning member 2b and the fixed positioning member 2a cooperate with each other and hold the first workpiece 3 to be gripped. The welding surface of the workpiece 3 is connected to the annular projection of the second workpiece 4
Contact 4b. On the other hand, the two parts 7a and 7b of the second welding electrode 7 are moved forward and close to each other by a drive mechanism (not shown), and as shown in FIG.
The facing surfaces of a and 7b are the large diameter portion 3a of the first workpiece 3.
The horizontal movement is stopped at a position slightly apart by a predetermined distance without touching the. Next, the two parts 7a, 7b are lowered and the two parts 7a, 7b are welded to the welding surface 4a of the second workpiece 4.
And a suitable pressing force is applied by a pressing mechanism (not shown) to reduce the contact resistance between the second welding electrode 7 and the welding surface 4a of the second workpiece 4.

At the same time, a downward pressing force (forging pressure) larger than the pressing force applied to the second welding electrode 7 is applied to the first welding electrode 1 by a pressing mechanism (not shown). Along with this, the spring member 13 contracts, and the pressing force is applied to the base mechanism 15 through the support member 10, the cradle 14, and the like.
Is added to At this time, even if the positioning mechanism 2 is operated to move the movable positioning member 2b backward, there is no problem since the first workpiece 3 does not move.

In this state, by closing the discharge control type switch SW shown in FIG. 3, the energy charged in the capacitor C is discharged at once, and the first workpiece 3 and the first workpiece 3 are discharged from the first welding electrode 1. A single large pulse-like welding current flows to the second welding electrode 7 through the joint with the second workpiece 4, and the first workpiece 3 and the second workpiece 4 are welded.

In this state, quenching is performed on the welded portions of the workpieces 3 and 4, and there is a possibility that the metal material may become brittle. An electric current is caused to flow through the joint between the workpiece 3 and the second workpiece 4. This tempering involves applying a single pulsed current that is smaller than the pulsed welding current, for example, about 70-80% and has a substantial time width of about 50 milliseconds or less. It is performed by flowing when it drops to the extent. What is important when performing this tempering is to maintain the pressurized state of the first welding electrode 1 and the second welding electrode 7 as they are, thereby making the welding electrode 1
Abutment surface between the workpiece 3 and the welding electrode 7 and the workpiece 4
Since the contact surfaces with each other are sufficiently familiar, good tempering can be performed in a short time of about 50 milliseconds or less. Here, the substantial time width means that the current value is 10% of its peak value.
The time at the above level.

As soon as the welding and tempering steps are completed, the first welding electrode 1 is raised, the second welding electrode 7 is also raised once and then retreated in the horizontal direction. The chuck mechanism 6 also performs the diameter expanding operation. Thereafter, the welded first workpiece 3 and second workpiece 4 are taken out, and one cycle of the welding process is completed.

In the embodiment described above, the tempering step can be omitted depending on the metal material of the workpiece, the second welding electrode 7 is omitted, the insulating plate 8 is omitted, and the current is reduced. May flow to the base mechanism 15 through the support 5, the central stationary member 6 a of the collet chuck mechanism 6, the support 9, the support 10, and the support 14. When the second workpiece 4 has a stable shape such as a cube, a rectangular parallelepiped, or a cylindrical body, the collet chuck mechanism can be omitted. Further, the positioning mechanism 2 may hold the first workpiece 3 until one welding is completed, and when the position is fixed by the stopper mechanism, the fixed positioning member 2a is movable. It is also possible to make.

[0029]

As described above, according to the present invention, resistance welding is performed without using a die-set structure as the welding electrode and maintaining the coaxial accuracy between the workpieces without applying a pressing force from below. An apparatus and method can be provided.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a resistance welding apparatus according to the present invention.

FIG. 2 is a view showing a part of the resistance welding apparatus shown in FIG. 1.

FIG. 3 is a diagram illustrating an example of an electric circuit to which the present invention is applied.

[Explanation of symbols]

1 ・ ・ ・ First welding electrode 2 ・ ・ ・ Positioning mechanism 3 ・ ・ ・ First workpiece 4 ・ ・ ・ Second workpiece 5 ・ ・ ・ Brace 6 ・ ・ ・ Collet chuck mechanism 7 ・..Second welding electrode 8 ・ ・ ・ Insulating plate 9 ・ ・ ・ Support base 10 ・ ・ ・ Post member 11 ・ ・ ・ Linear guide mechanism 12 ・ ・ ・ X, Y
Direction drive mechanism 13 ・ ・ ・ Spring member 14 ・ ・ ・ Receiver base 15 ・ ・ ・ Base mechanism

Claims (3)

[Claims] 1. A resistance welding apparatus for performing resistance welding of a rod-shaped first workpiece and a second workpiece which is longer than a diameter thereof, and having a mechanical strength capable of withstanding a pressure applied during welding. A base mechanism, an X, Y direction drive mechanism capable of moving the second workpiece in the X direction and the Y direction, and a second linear guide mechanism that supports the second workpiece and supports the second workpiece. A support mechanism coupled to a part of the X, Y direction drive mechanism; and a support mechanism provided between the X, Y direction drive mechanism and the support mechanism, wherein the support mechanism is mounted on the base in a state where no external pressure is applied. A spring mechanism that allows the bearing mechanism to move up and down, and a first welding electrode that can support the first workpiece; and a first welding electrode that cooperates with the first welding electrode. A welding current is applied to the joint surface between the workpiece and the second workpiece. That the second welding electrode and the resistance welding apparatus comprising the. 2. A first welding electrode and a second welding electrode for performing resistance welding by flowing a welding current between a first workpiece and a second workpiece in a rod shape longer than the diameter. In the resistance welding apparatus having: a positioning mechanism that grips and positions the first workpiece to be positioned in the middle of the first welding electrode in a longitudinal direction, wherein the positioning mechanism includes the first welding electrode. A first positioning member extending from an opening in the middle of the electrode to a set position in the longitudinal cavity, and advancing through an opening provided in the middle of the longitudinal wall of the first welding electrode, and retreating selectively to A resistance welding apparatus comprising a rod-shaped first workpiece and a second positioning member for positioning by cooperating and gripping the first positioning member. 3. A resistance welding method for performing resistance welding by flowing a welding current between a first workpiece and a second workpiece having a rod shape longer than a diameter thereof, wherein the welding current is passed. Sometimes at least the pressure applied by the first welding electrode to the workpiece is maintained even after the welding current has become substantially zero, and the welding portion of the first workpiece and the second workpiece is maintained. A resistance welding method, characterized in that a single pulsed current is passed when tempering is reduced to about the transformation point, tempering is performed, and then the pressing force of the first welding electrode is released.