JPH04305378A - Electric monitoring method for weld zone - Google Patents

Abstract

PURPOSE:To accurately monitor a welding state of a weld zone. CONSTITUTION:A calorific value of the weld zone is converted into an analog voltage waveform by an infrared sensor 16, this analog voltage waveform is concerted into a digital voltage waveform by an A/D converter part 17A, these digital voltage waveform data are compared and discriminated 18 with the digital data of a preset standard waveform by a microcomputer and a discriminated result obtained by this discrimination is displayed on a typewriter 19 (output).

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for monitoring electric welds that can be easily and reliably monitored.

0002

2. Description of the Related Art As a means of connecting two types of metal wires, there is a method of welding them together by pressurizing the metal wires, bringing them into contact, passing an electric current, and generating resistance heat. The quality of the welding can be determined by inspecting each weld after welding, but in reality, welding waveforms during electric welding are observed and monitored. In other words, the welding state can be known from the waveform of the welding voltage generated during welding. Conventionally, a synchroscope or the like has been used as a means of monitoring, and the waveform displayed on a cathode ray tube has been observed.

0003

[Problem to be Solved by the Invention] This method has the advantage of being able to accurately observe the waveforms because it is directly visually checked to determine whether they are normal or not. However, it requires skill to judge the observed waveforms. There are drawbacks. In addition, it took a considerable amount of time to observe, making it unsuitable for mass-produced products.

Therefore, it is possible to automatically detect the welding waveform, compare it with a standard waveform, and output the comparison result as a hard copy, so that waveform discrimination can be performed reliably and quickly, which is particularly useful in mass production processes. A suitable waveform monitoring method for electric welding is known from Japanese Patent Publication No. 60-2066.

In this publication, as shown in FIG. 3, when a voltage is applied to the primary winding of the welding power source transformer 5, a transformed voltage is generated in the secondary winding, and this is applied to the welding electrodes 1 and 2. be done. As a result, current flows through the metal wires 3 and 4,
At this time, resistance heat is generated at the contact point between the metal wires 3 and 4 and heated. If the metal wires 3 and 4 are pressurized during this heating, welding will occur. At this time, a welding current also flows through the resistor 6, and the welding is monitored by the voltage waveform of the welding current.

However, this method simply monitors the welding current, and is insufficient to confirm the actual welding state of the welded portion heated by this welding current.

The present invention has been made in view of the above-mentioned points, and its object is to provide a method for monitoring an electric welding part by which the welding condition of the welding part can be reliably monitored.

[0008]

[Means for Solving the Problems] The present invention provides means for converting the amount of heat generated in a welding part into an analog voltage waveform, means for converting the voltage waveform obtained by this means into a digital voltage waveform, and the digital voltage waveform. An electric welding part characterized by comprising a means for comparing and discriminating the data with digital data of a standard waveform set in advance, and a means for displaying the discrimination result obtained by the discriminating means. This is a monitoring method.

[0009]

[Operation] The amount of heat generated in the welded portion is detected by an infrared sensor, and the welding condition of the welded portion is detected and determined based on the temporal change in the amount of heat generated.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numerals 11 and 12 indicate welding electrodes that are arranged facing each other at a predetermined interval. Each of these electrodes 11,1
For example, a thick metal wire 13 and a thin metal wire 14 are attached to the wires 2, respectively. Each metal wire 13, 14 is supported such that the ends to be welded are in contact with each other. Also, welding electrode 11
, 12, a secondary winding of a welding power source transformer 15 is connected between the welding power source transformer 15 and the welding power source transformer 15.

Reference numeral 16 denotes an infrared sensor that detects infrared rays according to the amount of heat emitted from the welding part and outputs an analog voltage corresponding to the amount of heat generated. This infrared sensor 16 includes an optical fiber 161 whose end is disposed close to the welding part, a light receiving part 162 that detects infrared rays emitted from the welding part via this optical fiber 161, and an output of this light receiving part 162. It is composed of an amplifier 163 for amplification.

The analog output of this infrared sensor 161 is connected to a memory 17 having an A/D converter, and this memory 17 is further connected to a microcomputer 18. Furthermore, a typewriter 19 is connected to this microcomputer 18.

Next, the operation will be explained. First, when a voltage is applied to the primary winding of the welding power transformer 15, a transformed voltage is generated in the secondary winding, and this is applied to the welding electrode 11,
12. As a result, a current flows through the metal wires 13 and 14, and at this time, resistance heat is generated at the contact point between the metal wires 13 and 14, and the metal wires 13 and 14 are heated. If the metal wires 3 and 4 are pressurized during this heating, welding will occur. And metal wire 1
The infrared sensor 16 detects the amount of heat generated when resistance heat is generated at the contact point between the parts 3 and 14. Then, the analog voltage waveform corresponding to the amount of heat generated is stored in the memory 17.
be taken into account.

In this memory 17, first, the analog value of the voltage taken in is divided into fixed time units, sequentially A/D converted by an A/D converter 17A, and stored as a digital value in a memory section 17B. The digital data of this memorized waveform is transferred to the microcomputer 18, and the standard waveform data [upper limit waveform (A), lower limit waveform (B)] stored in advance in this microcomputer 18 is transferred to the microcomputer 18. ] compared to As a result of this comparison, if the measured waveform is outside the standard, an output is generated, for example, a typewriter is operated and some display is made on a hard copy.

That is, as shown in FIG. 2, the detected waveform falls between the upper limit waveform (A) and the lower limit waveform (B) (
Conditions a) to (c) are determined to be non-defective, and the detected waveform deviates from the upper limit waveform (A) or lower limit waveform (B) (d)
The condition of the product is determined to be defective.

[0016] The worker can immediately determine the welding condition by looking at this hard copy. Therefore, unlike the conventional synchroscope, it does not take much time to perform the discrimination, and it is very quick and has an excellent effect on process control of mass-produced products. Furthermore, there is no need to assign an expert to monitor factors. Of course, rather than making a judgment by looking at the waveform as it is, it is compared and determined digitally, which eliminates misjudgments such as estimates and improves the accuracy of the monitor.

Although the embodiments have been explained using resistance welding materials as an example, the present invention is not limited to this, and percussion welding and arc welding can also be used. Furthermore, although the waveform comparison is performed by a microcomputer, it may be of any other configuration as long as it has the ability to store standard waveforms and to compare them. Furthermore, although a typewriter is used to take out the hard copy, a general line printer may also be used, and instead of displaying only non-standard waveforms, it can also be displayed using X-ray-Y-ray coordinates. good. Further, the detected data may not only be output unconditionally, but may also be outputted in an interrupt manner, for example, by operating a push button.

[0018]

As described in detail above, according to the present invention, since the quality of welding is determined based on the amount of heat generated in the welded part, it is possible to accurately determine the quality of the welded part.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an apparatus to which the electric welding waveform monitoring method of the present invention is applied.

FIG. 2 is a diagram showing standard waveforms.

FIG. 3 is a diagram showing an apparatus to which a conventional electric welding waveform monitoring method is applied.

[Explanation of symbols]

11, 12...Welding electrode, 13...Thick metal wire, 14...Thin metal wire, 15...Welding power supply transformer, 16...Infrared sensor, 17...Memory, 18...Microcomputer, 19...
typewriter.

Claims (1)

[Claims] [Claim 1] A means for converting the amount of heat generated in a welding part into an analog voltage waveform, a means for converting the voltage waveform obtained by this means into a digital voltage waveform, and a preset 1. A method for monitoring an electric weld, comprising means for comparing and discriminating digital data of a standard waveform, and means for displaying a discrimination result obtained by the discriminating means.