JPH09248676A - Resistance welding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fully automate switching and controlling of welding conditions by making the pressurizing of a welding head numerically controlled and also providing a mechanism for measuring the pressurization. SOLUTION: Using a pulse motor 9 in driving an NC machining mechanism, a ball screw 6 and a ball nut 7 are attached to the motor shaft, enabling an electrode 1 to be positioned at an arbitrary speed. In other words, the electrode is moved at high speed to a tentative origin slightly before coming into contact with an object to be welded; then, after slowly descending to be in contact with the object, the electrode stops at the position where a spring 3 is contracted with a limit switch 13 turned ON inside the head; upon completion of welding, the electrode moves at high speed to the position of the tentative origin, ending a series of operation. Then, with a pressurizing force confirmed using a strain gauge 10, and with the abrasion loss (L0 -L1 ) of the electrode determined, switching is performed for the optimum welding conditions according to the length of an electrode and for the pressurizing timing, as preliminarily obtained from experiments. Thus, stable welding is efficiently carried out without the requirement for human intervention.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for fully automating a resistance welding apparatus, and more particularly to a mechanism and a control system for stabilizing welding quality.

[0002]

2. Description of the Related Art In the prior art, a welding mechanism normally pressurizes an object to be welded with a constant pressure to apply an arbitrary electric current to perform welding.
There are various items that determine the welding quality, and improvements have been made in terms of the mechanism for maintaining it stably and in terms of usability. For example, as disclosed in Japanese Patent Laid-Open No. 60-223669, there is a method of controlling the air supplied into a cylinder for pressurizing an object to be welded so that the pressure is kept constant. Similarly, as described in JP-A-61-253189, there is also a system in which the electrodes are driven by a torque motor so that the pressing force is constant and the height of the electrodes can be freely changed to improve workability.

[0003]

The resistance welding will be described below.

In resistance welding, pressure is applied to the object to be welded with a constant force, a voltage is applied between the electrodes, a current is passed through the object to be welded, and the Joule heat generated thereby melts and joins.

The current required for the coupling is determined by the voltage and time applied between the electrodes, the work piece to be welded, the electrode used, and the contact resistance between the other electrode and the work piece and the work piece to be welded. Involved. This contact resistance changes depending on the size of pressing the object to be welded.

That is, in order to stabilize the welding quality, it is necessary to stabilize the above four items. However, in the above-mentioned conventional technique, the electrodes and the contact resistance to be used have not been sufficiently studied, the method is deficient, and the management is insufficient. For this reason, in the conventional method, as described above, there are many problems in quality, and it is difficult to fully automate welding. In some form, humans always intervene, resulting in inefficient equipment.

The present invention automatically controls the above four items.
The objective is to realize fully automated equipment with stable quality controlled.

[0008]

In order to achieve the above object, an automatic welding apparatus is provided with an NC pressurizing mechanism, a pressurizing measuring mechanism and a control device for controlling each.

Since the NC pressurizing mechanism is mounted for driving the spring type constant pressure welding head, the electrode can be positioned at any speed and at any position.

The pressure measuring mechanism has a strain gauge attached at the same height as the work to be welded. When pressure is applied by the electrode, the pressure is displayed and output externally by the indicator. It becomes possible to make it constant.

In addition, the operation of controlling these mechanisms will be described with reference to the drawings.

As shown in FIG. 2, the electrode is measured by first moving the head down and contacting the strain gauge with the amount of movement L from the origin.
Remember 0. Then, after welding is performed several times, the head is lowered again and L1 is similarly stored. From this result, the electrode length l-the amount of wear of the electrode (L0-L1) is calculated. As a result, the optimum conditions for each electrode length obtained in advance are switched.

In order to shorten the working time, the electrodes move at a high speed to a temporary origin (L0-X) slightly before the contact with the non-welded object, and then accelerate to reduce the vibration due to the contact with the non-welded object. Stops at the position (L0 + h) where the spring is compressed and the limit switch inside the head is turned ON after it descends along a smooth cycloid curve and contacts the non-welded object,
After welding, it moves to the temporary origin position at high speed and completes a series of operations.

According to the system control method described above, even when pressure is applied simultaneously from above and below to perform welding, human intervention is not required regardless of the difference in the amount of wear of the upper and lower electrodes, and stable welding is always performed efficiently. More specifically, if pressure is applied from above and below as shown in FIG. 6, the non-welded product vibrates up and down due to the shift in the timing of contact with the non-welded product, so the pressure also fluctuates accordingly and the energization starts outside the effective pressure range. There is a possibility that they will be welded, resulting in welding defects such as excessive deformation and sparks. In order to avoid this phenomenon, there is a method of delaying energization until the vibration subsides, but since it is inefficient, it is necessary to adjust the distance from the electrode tip to the non-welded object and the movement time. Can be realized.

Further, even when the size of the non-welded object is different, the moving speed, the stop position and the like can be freely controlled by the NC mechanism, so that it is possible to cope with the situation.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment using the present invention will be described with reference to the drawings.

FIG. 4 shows a cable 1 which is a target product of the embodiment.
5 is a perspective view of the connector 14 and as shown in the figure, the connector is formed by arranging the terminals in two rows in a row at a constant pitch, and the cable core wire is formed so as to be arranged in the connector terminals.
3 is an external view of a connector welding apparatus according to an embodiment of the present invention, in which a combination position of a loader 17 for transporting a pallet 16 having a cable 15 fixed therein, a connector supply unit 26 for supplying a connector 14, and a cable 15 is determined. Detection unit 18, a combination mechanism 19 that combines the connector 14 and the cable 15, an NC pressurization mechanism 2 that pressurizes the work.
0, a feeding mechanism 21 for moving the NC pressurizing mechanism, a welding power source 22 for supplying an electric current, a pressurizing measuring mechanism 2 for measuring pressurization
3, a polishing mechanism 24 for polishing the electrode surface, an operation panel 25, and the like.

The operation sequence is such that the connector 14 supplied from the connector supply unit 26 and positioned in the combination mechanism is combined with the cable 15 conveyed by the loader 17 and detected by the detection unit 18 and positioned, and the feeding mechanism 21 performs NC addition. While feeding the pressure mechanism 20 to the connector position and feeding the pitch, N
Welding power source 22 that applies pressure from above and below by C pressure mechanism 20
Is supplied with electric current to perform welding. Then, the NC pressurizing mechanism 20 is sent to the polishing mechanism section 24, and the feeding mechanism 21 moves while applying pressure to polish the electrode.

Next, the pressing mechanism of the present invention will be described in detail.

FIG. 1 is a simplified algae type diagram of the present pressurizing mechanism. As shown in the figure, an electrode 1 and an electrode holder 2 for holding it are shown.
A compression spring 3 for applying a pressure thereto, an arm 4 for moving the electrode holder 2 by contacting the compression spring 3, a bearing 5 for sliding the electrode holder 2 and the arm 4, and a ball screw 6 for driving the arm 4. Ball nut 7, bearing 8 for guiding it, and pulse motor 9 as a drive source
And a strain gauge 10 for measuring pressurization, an indicator 11 for displaying, and the like. The operation is such that when the pulse motor 9 rotates arbitrarily, the ball screw also rotates and the ball nut 7
Moves, and the arm 4, the spring 3, the electrode holder 2, and the electrode 1 move and come into contact with the connector. When the electrode is further rotated, the spring 3 is compressed and the pressure is increased while the electrode is in contact with the connector, and the dog 12 attached to the electrode holder 2 is moved to the limit switch 12 attached to the arm 4. Energization is started by making contact. With the same operation as this, the pressing force is measured by the strain gauge 10 and the indicator 11.

Regarding the welding conditions, three types of connectors and three types of cables each have two types of core wire diameters, so switching is required at any time, and the optimum conditions also differ depending on the electrode length. This device obtains each condition in advance by experiments, creates a database of welding conditions for each cable / connector combination for each electrode length, measures the electrode length to the welding power source, transfers the data, and then inside the welding power source during welding operation. The welding conditions for each cable / connector combination were switched.

For the electrode length, an initial value is input at the time of electrode replacement, and after that, it is fully automatically controlled by an automatic electrode length measuring method, and when the wear reaches the limit electrode length, an alarm is notified to the operator to replace the electrode. In addition, a good range is set for the pressing force, and if it deviates from the range, the operator is informed by an alarm similarly.

[0023]

According to the present invention, since the welding conditions corresponding to the workpiece can be switched and the respective conditions can be managed in a fully automatic manner, there is no human intervention and there is an effect of improving the operation rate of the device and stabilizing the connection quality. can get.

[Brief description of drawings]

FIG. 1 is a pressurization mechanism algae diagram of the present invention.

FIG. 2 is a diagram of an electrode measuring method of the present invention.

FIG. 3 is an electrode operation control system diagram of the present invention.

FIG. 4 is a perspective view of a target work according to an embodiment of the present invention.

FIG. 5 is an external view of an apparatus according to an embodiment of the present invention.

FIG. 6 is a work vibration state of upper and lower simultaneous welding.

[Explanation of symbols]

1 ... Electrode, 2 ... Electrode holder, 3 ... Compression spring,
4 ... Arm, 5 ... Bearing, 6 ... Ball screw, 7
… Ball nut, 8… Bearing, 9… Pulse motor,
10 ... Strain gauge, 11 ... Indicator, 12 ... Dog, 13 ... Limit switch, 14 ... Connector, 15 ... Cable, 16 ... Pallet, 17 ... Loader, 18 ... Detecting part, 19 ... Combination mechanism, 20 ... N
C pressurizing mechanism, 21 ... feeding mechanism, 22 ... welding power source, 23 ...
Pressure measuring mechanism, 24 ... Polishing mechanism, 25 ... Operation panel, 2
6 ... Connector supply section.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location // H01R 43/02 H01R 43/02 B

Claims (3)

[Claims] 1. A resistance welding apparatus for welding a workpiece by pressurizing an object to be welded with an electrode equipped with a pressurizing mechanism and passing an electric current through the motor, which is connected to a motor and an output shaft of the motor for driving a pressing head. A resistance welding apparatus, which uses an NC mechanism composed of a ball screw and a nut of the ball screw, and is equipped with a mechanism for measuring a pressure at the time of pressurization to perform stable welding. 2. A resistance welding apparatus having a control device for automatically measuring the length of an electrode using the above mechanism and switching the optimum welding condition according to the result. 3. A resistance welding apparatus having a mechanism in which the above mechanisms are installed symmetrically in the vertical direction and simultaneously pressurizing from the upper and lower sides to perform welding on the upper and lower sides respectively, and a control device for starting energization at the same timing as the upper and lower sides.