JPH01299783A - Device for controlling welding - Google Patents

Abstract

PURPOSE:To uniformize the quality at welding part by arranging melting velocity detecting means of the welding part, setting melting condition storing means and executing melting control based on comparison of the detected melting velocity with the standard melting velocity. CONSTITUTION:At the time of welding while pressurizing end parts of two flat plates 3a, 3b from vertical direction with pressurizing electrode terminals 4a, 4b a pressure detector 5 and displacement detector 6 are set to the upper electrode terminal 4a. The storing part 16 connecting with a main control part 18 is arranged to store each welding condition of the part to be welded and the standard electrode displacement curve (melting velocity curve). Electricity is conducted to the electrode terminals 4a, 4b and also the pressurized force and displacement rate of the electrode 4a are transferred to the main control part 18 and the welding control is executed while comparing the electrode displacement rate with the standard displacement curve at every prescribed times so that both coincide. As the welding can be controlled with the standard melting velocity, the quality at the welding part is uniformized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a welding control device that changes welding conditions based on the melting rate of a workpiece.

(Prior Art) As a conventional method for determining the quality of spot welding, there is a method using a thermal expansion monitor.

This method utilizes the fact that the movable electrode is pushed up by the expansion of the welded part due to the rise in temperature during welding.
The amount of displacement of the movable electrode at this time is detected, and when it reaches the maximum value of the inflection point, it is determined that welding has been performed normally and the current supply is stopped.

(Problem to be Solved by the Invention) However, in this method using a thermal expansion monitor, the quality of the welding condition is determined based on whether the inflection point of the electrode displacement reaches the maximum value as a result of energization. During the welding process, it was not possible to judge whether the welding condition was good or bad.

(Means for Solving the Problems) The welding control device of the present invention has been made in view of the actual situation, and includes a melting speed detection means for detecting the melting speed of a welding part of a workpiece, and a type of workpiece. a condition storage means for storing each welding condition and a standard melting rate condition of the workpiece under the welding condition, the melting rate detected by the melting rate detection means and the melting rate stored in the condition storage means; The welding condition is determined by constantly comparing the melting rate with the standard melting rate under the welding conditions.

Further, there is a comparison means for comparing the melting rate detected by the melting rate detection means with the standard melting rate under the welding conditions stored in the condition storage means, and the actual melting rate is determined based on the comparison result of this comparison means. and control means for controlling the melting rate to match the standard melting rate.

(Function) The melting speed of the welded portion of the object to be welded is detected by the melting speed detection means. The melting rate here refers to the amount of electrode displacement of a pressure electrode terminal that is brought into pressure contact with the welding part of the workpiece.

Further, the welding conditions for each type of workpiece and the standard melting rate conditions for the workpiece under the welding conditions (i.e., electrode displacement curve data from the start of welding to the end of welding) are stored in advance in the condition storage means. .

Then, the comparison means compares the actual electrode displacement amount detected by the melting rate detection means with the standard electrode displacement curve data under the welding conditions stored in the condition storage means, and the actual electrode displacement amount is If the actual amount of electrode displacement is below the electrode displacement curve, increase the applied current or decrease the pressure applied to the pressurized electrode terminal, and if the actual amount of electrode displacement is below the electrode displacement curve, increase the applied current or decrease the applied current. The control means controls to increase the pressing force of the pressurizing electrode terminal.

Typical welding conditions include flat plate welding in which flat plates are welded together, projection welding in which projections are provided on flat plates, and pipe welding in which pipes are welded together.

FIG. 5 shows the electrode displacement curve of the pressurized electrode terminal when welding is performed under these various welding conditions and the welding is performed normally. In the same figure, the electrode displacement curves are for flat plate welding, ■ for projection welding, and ■ for pipe welding. In addition, FIGS. 6(a) and 6(b) show the waveforms of the current flowing to the pressurizing electrode terminal; FIG. 6(a) shows the AC type, and FIG.
b) is a direct current type.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic configuration diagram of a welding control device of the present invention. In this embodiment, projection welding of the three types of welding conditions described above will be explained as an example.

In the figure, 1 is a pressurizing device, 2 is a welding device,
The ends of the two flat plates 3a, 3b are overlapped, and the overlapping welded portions are sandwiched from both the upper and lower directions, and the pressure electrode terminals 4a, 4b are pressed into contact with each other. The pressurized electrode terminals 4a, 4b are connected to the lower pressurized electrode terminal 4b on the main body of the device (
(not shown), and the upper pressurizing electrode terminal 4a is provided so as to be movable in the vertical direction. Although not shown, protrusions are formed at the welded portions of the flat plates 3a and 3b (on opposing surfaces). Further, a pressurizing force detector 5 for detecting the pressurizing force is provided on the pressurizing electrode terminal 4a disposed at the top, and a displacement detector 6 for detecting the amount of displacement in the vertical direction is also provided.

The upper pressurizing electrode terminal 4a is connected to the secondary coil of the transformer 10 via diodes D, D2, and the lower pressurizing electrode terminal 4b is connected to a connecting wire led out from the middle point of the secondary coil. are connected to each other.

Further, a rectifying section 8 and an inverter control section 9 are connected between the primary coil of the transformer 10 and the three-phase power supply 7.

Further, 11 is a pressure detection section that detects the pressure force via the pressure force detector 5, 12 is a displacement detection section that detects the amount of displacement of the pressure electrode terminal 4a via the displacement detector 6, and 13 is a connection line. 14 is a current detecting section that detects the current supplied to the pressurizing electrode terminal 4b via this current detector 13; 15 is a current detecting section that detects the current supplied to the pressurizing electrode terminal 4b; An A/D converter 16 converts an analog signal detected by the current detector 14 into a digital signal, and an A/D converter 16 shows welding condition data for each type of workpiece and the standard pressure electrode terminals 4a, 4b in the welding condition data. a storage section 17 for storing electrode displacement amount data, etc., a setting and display section 17 for setting the type of object to be welded, welding conditions, etc., and displaying the welding state;
Reference numeral 8 denotes detection data from the A/D conversion section 15, data stored in the storage section 16, and the setting and display section 1.
A main control section 19 includes a CPU, etc., which performs various arithmetic processing based on setting data etc. from 7, and a main control section 19 controls the inverter control section 9 according to instructions from the main control section 18, A welding control section 20 that varies the supplied current value is a pressurization control section that controls the pressurizing device 1 according to instructions from the main control section 18 and controls the pressurizing force of the pressurizing electrode terminals 4a and 4b.

Next, the operation of the welding control device having the above configuration will be explained with reference to the electrode displacement curve shown in FIG.

In the figure, ■ indicates when normal welding is performed, ■ indicates when the current value supplied to the pressure electrode terminals 4a, 4b is small or the pressure force is large, and ■ indicates when the welding is performed normally. Each electrode displacement curve is shown when the supplied current value is large or the applied force is small.

First, from the setting and display section 17, projection welding is set as the type of welding to be performed, and furthermore, the shape, dimensions, material, etc. of the welded part of the workpiece are set. Then, the electrode displacement amount data (electrode displacement curve data indicated by ■ in FIG. 2) that meets this condition is read from the storage section 16 into the main control section 18. Next, the ends of the two flat plates 3a and 3b are overlapped, and the overlapping welded portions are brought into pressure contact with each other by sandwiching them from both the upper and lower directions using the pressurizing electrode terminals 4a and 4b. Thereafter, pressure is applied at a constant pressure by the pressure device 1 (initial pressure) to crush the protrusion formed on the joint surface of the welded portion. Next, 607 (or 507) AC power is supplied from the three-phase power supply 7, rectified by the rectifier 8, and then converted to a high frequency (approximately I KHz) by the inverter control unit 9.
The DC current rectified again via the transformer 10 is applied to the pressurizing electrode terminal 4a.

4b and start projection welding.

During this welding, the pressing force of the pressing electrode terminals 4a, 4b detected by the pressing force detector 5, the electrode displacement amount of the pressing electrode terminal 4a detected by the displacement detector 6, and the electrode displacement amount of the pressing electrode terminal 4a detected by the current detector 13 are detected. Detected pressurized electrode terminals 4a, 4b
The value of the current supplied to the main controller 18 is taken into the main controller 18.

In the main control unit 18, the electrode displacement amount data (hereinafter referred to as electrode displacement curve data ■) read from the storage unit 16,
The amount of electrode displacement (hereinafter referred to as the detected value) of the pressurizing electrode terminal 4a detected at regular intervals (for example, every 0.5 to 1.0 m5ec) is compared at any time, and the detected value is determined as the electrode displacement curve data ■. Welding control section 19 and pressurization control section 2 so as to match.
Controls 0.

That is, when the detected value deviates upward from the electrode displacement curve data ■ (in the case of a value close to the electrode displacement curve data ■), the welding control section 19 is controlled to
, 4b is made larger by Δ■ than the current value detected by the current detection section 14, or the pressure control section 20 is controlled to increase the pressure applied to the pressure electrode terminals 4a and 4b. The pressurizing force P detected by the pressurizing detecting section 11 is made smaller by ΔP to bring it closer to matching the electrode displacement curve data ■.

In addition, if the detected value deviates downward from the electrode displacement curve data ■ (in the case of a value close to the electrode displacement curve data ■), the welding control unit 19 is controlled to
The current value detected by the current detection unit 14 is the current supplied to b.
', or by controlling the pressure control section 20, the pressure applied to the pressure electrode terminals 4a, 4b is made smaller than the pressure P' detected by the pressure detection section 11. It is made thicker by ΔP' (and brought closer to match the electrode displacement curve data ■).

Note that the comparison between the detected value during welding and the electrode displacement curve data (2) is displayed on the setting and display section 17, so that the operator can judge the welding state by directly viewing it with his or her mouth.

In this way, the welding condition is determined by constantly comparing the detected value of the pressurizing force detector 5 during welding with the electrode displacement curve data (■) from the storage unit 16, and the detected value deviates from the electrode displacement curve data (■). In such a case, each control section 19 should be adjusted to eliminate this deviation.
．． By controlling 20, welding can be performed in good condition.

In the above embodiment, an inverter method is adopted as the method for supplying current to the pressurizing electrode terminals 4a and 4b, but a single-phase AC method shown in FIG. 3 or a DC method shown in FIG. 4 may be used. It is also possible to obtain sufficient effects.

Furthermore, in the above embodiment, the displacement it(
Welding equipment 2
However, it is also possible to control the welding device 2 while monitoring the acceleration of the pressurizing electrode terminal 4a obtained by differentiating this speed.

Further, in the above embodiments, the case of projection welding is explained, but it goes without saying that the present apparatus can be similarly applied to flat plate welding and pipe welding.

Furthermore, in the above embodiment, the storage unit 1 stores welding condition data for each type of workpiece and standard electrode displacement data of the pressurizing electrode terminals 4a, 4b in the welding condition data.
6, the welding condition data and electrode displacement amount data are stored in the memory card.
This memory card reader/writer device may be used to import necessary data into the main control section 18 at any time. In this way, even if there is a large amount of data to be stored, it is sufficient to classify each workpiece and create a memory card, and there is no need to provide a large-capacity storage section 16, reducing costs. It can also be provided at low cost. You can also erase data that is no longer needed and write new data.

(Effects of the Invention) As explained above, according to the welding control device of the present invention,
While constantly comparing the melting rate detected by the melting rate detection means with the standard melting rate under the welding conditions stored in the condition storage means, the actual melting rate is set to the standard based on the comparison result. Since the melting rate is controlled to match the typical melting rate, the best welding condition can always be maintained regardless of the type of workpiece or welding conditions.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of the welding control device of the present invention, Fig. 2 is an electrode displacement curve diagram during projection welding, and Figs. 3 and 4 are circuit diagrams showing other methods of energizing the pressurized electrode terminal. ,
FIG. 5 is an electrode displacement curve diagram under various welding conditions, and FIGS. 6(a) and (b) are waveform diagrams of the current flowing to the pressurized electrode terminal. 1... Pressure device 2... Welding device 3a, 3b... Work to be welded 4a, 4b... Pressure electrode terminal 5... Pressure force detector 6... Displacement detector 7...・Three-phase power supply 8... Rectifier section 9... Inverter control section 10... Transformer 11... Pressure detection section 12... Displacement detection section 13... Current detector 14... Current detection Section 15... A/D conversion section 16... Storage section 17... Setting and display section 18... Main control section 19... Welding control section 20... Pressure control section

Claims (1)

[Scope of Claims] 1) Melting rate detection means for detecting the melting rate of the welded portion of the workpiece, welding conditions for each type of workpiece, and standard melting speed conditions for the weldwork under the welding conditions. and a condition storage means for storing the welding conditions, and the welding state is determined by comparing the melting rate detected by the melting rate detection means with a standard melting rate under the welding conditions stored in the condition storage means. A welding control device characterized in that: 2) Comparison means for constantly comparing the melting rate detected by the melting rate detection means with the standard melting rate under the welding conditions stored in the condition storage means, and determining the actual melting rate based on the comparison result of this comparison means. 2. The welding control device according to claim 1, further comprising control means for controlling the melting rate to match the standard melting rate.