JPH0424546A - Method for inspecting welding of drum of drum can - Google Patents

Abstract

PURPOSE:To omit visual monitoring and the airtightness test of a drum part by continuously detecting the temperatures of appropriate places during welding with a radiation thermometer, and comparing the detected value with a preset temperature range. CONSTITUTION:When the temperature at a measuring point is detected with a thermometer 3 as optical energy, the signal is sent into a photoelectric converter part 4 through an optical fiber 6 and converted into the electric signal. The signal is inputted into a control part 5. A specified temperature range is set in the control part 5. The measured temperature value at the seam-welded part which is inputted from the thermometer is compared with the preset temperature. When the measured value is located within the preset range, the welding is perfect.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for determining the quality of welded joints of can bodies based on temperature when manufacturing drums. This relates to the inspection method of the Department.

[Prior art] For example, 200 J, which is the most commonly used drum can
When manufacturing two cans, the manufacturing process for the can body involves roll-forming a plate material into a cylindrical shape, overlapping the opposing ends, and joining the stiff parts by seam welding.

Naturally, the quality of the weld is important when seam welding the can body. If this weld is defective, if left as is, it may cause a serious accident depending on the contents during use, so can bodies with such defective joints must be removed from the production line. be.

For the above reasons, when seam welding a can body, it is essential for workers to visually monitor the welded part during welding and to perform an airtight test on only the can body after seam welding.Through these monitoring and tests, Defective can bodies were being extracted.

[Problem to be solved by the invention] However, in the visual monitoring described above, a worker estimates the welding temperature based on the color of the welded part and judges whether the welded part is good or bad, and it is difficult to do so unless the worker is a skilled worker. It was not perfect as there was a risk of misjudgment, so it was necessary to re-check the airtightness of the torso.

Therefore, in the past, when manufacturing the body of a drum, such manual monitoring and airtightness testing were required, which was an important step in saving labor on the drum manufacturing line and improving can productivity. This was a major obstacle.

The present invention has been made in view of the problems of the prior art, and provides a highly reliable inspection method for the welded part of the drum body, which can omit the conventionally required visual monitoring and airtightness test of the body. The purpose is to provide

[Means for Solving the Problem] To achieve this object, the welded part inspection method according to the present invention is a method for inspecting a welded part of a drum can formed into a cylindrical shape in a drum manufacturing line, overlapping the opposing ends and joining them by welding. In the inspection method for body welds, the temperature at appropriate locations during welding is continuously detected using a radiation thermometer from a distant position, and this detected value is compared with a preset temperature range to detect welding defects. It is characterized by discrimination.

Furthermore, in the above method, dividing the temperature range to be set into a plurality of parts along the axial direction of the body of the drum enables more accurate inspection.

The present invention will be explained in detail below.

The present inventors have developed a number of methods for inspecting welds during seam welding of drum can bodies in order to obtain a more reliable and reliable inspection method for welds without the conventional visual monitoring and subsequent airtightness test of the can body. As a result of repeated experimental studies, it was discovered that accurately measuring the temperature of the weld zone to identify weld defects would be optimal for determining the quality of the weld zone.

That is, Figure 3 shows the results of an inspection of the welded part of the can body carried out by the present inventors, in which the welding current was varied and the temperature was measured, and the parts of the welded part of the can body were cut out at each temperature. , which shows the condition of the welded part (occurrence and distribution of cracks and flakes) when subjected to an Erichsen tester. The vertical axis shows the temperature, and the horizontal axis shows the axial position of the can body.

In Figure 3, the O mark indicates cracking due to the Erichsen test.
The X mark indicates peeling (peeling 1III) according to the Erichsen test, and the shaded area indicates the long range.

As can be seen from the figure, cracking and peeling occur mainly in part A (top part of the body) and part 0 (bottom part of the body), and peeling does not occur in central part B unless the temperature drops to 750°C or less. .

Moreover, cracks occur in part A at temperatures above 1400°C;
Peeling occurs even at temperatures of 20 to 850°C. This is considered to be because the top part is affected by vibrations of the mechanical system (air fluctuations), material speed fluctuations, etc. from the time the top part is held between the electrode rings, and thus becomes unstable. Note that defects similar to those in the top portion also occur in the bottom portion, but the degree of defects is smaller than in the top portion.

From the above, there is a close relationship between the temperature of the weld and weld defects, and if the weld temperature can be accurately measured during seam welding, it is possible to immediately determine whether the weld is good or bad based on this. It has been found that the top and bottom parts and the center part of a part have different mechanisms of defect generation, and that it is better to treat them as separate parts.

In addition, temperature changes in the seam welding area are actually caused by defects in the seam welding electrode wheel (adhesion of dust, etc.), fluctuations in the pressing force of the TL rod (particularly when the pressure decreases, the temperature rises), fluctuations in the current value, etc. This is thought to be due to.

The present invention was completed based on such knowledge, and it sets a temperature range in which a seam weld with no defects and no problems in terms of strength can be obtained, and detects a temperature outside this set range. In some cases, the can body is determined to have a welding defect.

FIG. 1 shows an example of equipment for carrying out the inspection method of the present invention. In the figure, 1 is a seam welded part of a plate forming the body of a drum, and 2a is the seam welded part 1. The lower electrode ring 2b disposed on the lower side of the electrode ring 2a is an upper electrode ring that is movable downward and holds the seam welded part 1 together with the electrode ring 2a.The pressing force can be adjusted by operating a pressing mechanism (not shown). Ru. All of these welding mechanisms are well known, and other necessary members and mechanisms will be omitted.

Further, 3 is a temperature sensor which is directed to the position during welding of the seam welding part 1 at the front upper blade of the electrode wheels 2a, 2b in the welding direction, and has an extremely fast response and continuously adjusts the welding temperature at a high degree. It is preferable to use a radiation thermometer that can detect The distance 1111 between the spot position S (i.e. temperature measurement point) directed by the thermometer 3 and the electrode ring clamping position (welding point) should be as close to the welding point as possible, but there are restrictions due to the structure of the welding machine. Therefore, l is approximately 60-70mm
shall be.

Furthermore, if the directivity angle θ is less than 30°, the emissivity will deteriorate, so it is desirable to set it to 30° or more, or to set the upper limit to about 40°.

Furthermore, in FIG. 1, 4 is a photoelectric conversion section, 5 is a control section, and 6 is an optical fiber that connects the thermometer 3 and the photoelectric conversion section 4.

In the present invention, when the temperature and optical energy at a measurement point are detected by the thermometer 3, this signal is sent to the photoelectric conversion section 4 via the optical fiber 6, converted into an electrical signal, and inputted to the control section 5. Ru. This control unit 5 has a fixed temperature range set, and compares the measured value of the temperature of the seam weld input from the thermometer with this set temperature, and if the measured value is within the set range, the seam weld is If the welding continues and the welding does not deviate from the range from the start to the end, the welded part is deemed to be free of defects and the can body is sent to the next process. On the other hand, if the measured temperature value falls outside the set range, the can body is determined to be defective at the welding part and is removed from the production line, for example, according to a command from the control section 5.

An example of the setting pattern of the above-mentioned temperature setting will be explained with reference to FIG. In Fig. 2, the temperature control range is first divided into a plurality of parts, for example, the trunk tip A, the central part BI & the end C, but of course after this, the tip and rear ends are divided, and then It is also possible to perform detailed management. 1A,
1. ．． 1C indicates the reference value of the F limit of the set temperature at the above-mentioned tip A, center B, and rear end C, and the values vary depending on the steel plate to be welded or the welding machine. In addition, when setting the standard, it depends on the temperature measuring position and angle of the radiation thermometer, as well as mechanical conditions such as welding speed, electrode ring pressure, and welding current, so it is usually done by keeping the welding conditions constant.
Let us decide A, 1B, and 1c. Furthermore, the upper limit of the set temperature can be determined once the lower limit is determined, and approximately 1.6 to 1.7 times the lower limit temperature is appropriate.

In Figure 2, body length: 913mm, tip A: 6
Table 1 shows specific welding conditions, materials, and temperature setting examples in the case of 0 to loomm and rear end B: 60 to 100 m1I+.

[Effects of the Invention] According to the inspection method of the present invention explained above, the inspection granularity of the seam welded part of the can body is high and the reliability is improved. The airtightness test can be omitted (the airtightness test is the only airtightness test performed on the finished product after the top and bottom plates are installed), and significant labor savings can be achieved.
Improve drum productivity.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an example of equipment for carrying out the method of the present invention;
FIG. 2 is an explanatory diagram of the reference temperature setting pattern in the present invention, and FIG. 3 is a graph showing the results of experiments conducted by the present inventors. DESCRIPTION OF SYMBOLS 1... Seam welding part, 2... Electrode ring, 3... Radiation thermometer, 4... Photoelectric conversion part, 5... Control part, 6...
・Optical fiber

Claims (1)

[Claims] 1. In a method for inspecting a welded part of a body of a drum can formed into a cylindrical shape in a drum production line, the opposing ends are overlapped and joined by welding, the temperature at appropriate points during the welding is checked. A method for inspecting a welded part of a drum can body, which comprises continuously detecting a welded part of a drum can body from a remote position using a radiation thermometer, and comparing the detected value with a preset temperature range to determine a welding defect. 2. The inspection method according to claim 1, which comprises dividing the temperature range to be set into a plurality of parts along the axial direction of the body of the drum.