JP2898351B2 - Inspection method of drum can body weld - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] In the present invention, a method for inspecting a welded portion of a drum can body which can determine the quality of a welded joint of the can body based on a temperature when manufacturing the drum can. It is about.

[Prior art] For example, when manufacturing a 200-liter can that is most commonly used as a drum can, a plate material is roll-formed into a cylindrical shape as a manufacturing process of a can body, and the opposite ends are overlapped with each other. There is a joining process by seam welding.

In the above seam welding of the can body, the quality of the welded portion is naturally important. If this weld is bad,
If this is left as it is, a serious accident may be caused depending on the contents during use. Therefore, it is necessary to take out such a can body having a defective joint from the production line.

For the above-mentioned reasons, when seam welding the can body, it is essential that a worker visually monitor the welded part during welding and an airtight test of only the can body performed after seam welding,
Through these monitoring and testing, defective can bodies were extracted.

[Problems to be Solved by the Invention] However, in the above-described visual monitoring, the worker estimates the welding temperature based on the color of the welded portion and judges the quality of the welded portion. It was not perfect because there was a risk of making mistakes, so it was necessary to recheck the body in an airtight test.

Therefore, in the case of manufacturing the body of a drum can, conventionally, such manual monitoring and airtightness test are indispensable. Therefore, in order to save labor in a drum can production line and improve can productivity. It was a major obstacle.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems of the related art, and a highly reliable method of inspecting a drum can body welded part, which can omit the visual monitoring and the airtightness test of the body, which has been conventionally required, can be omitted. The purpose is to provide.

[Means for Solving the Problems] In order to achieve this object, a method for inspecting a welded portion according to the present invention is directed to a method for forming a cylindrical shape in a drum can production line, overlapping the opposite ends, and joining the drum cans by welding. In the method of inspecting the body weld, the temperature of an appropriate portion during the welding is continuously detected by a radiation thermometer from a separated position, and the detected value is determined by a plurality of values along the body axis direction of the drum. Divide and compare with the preset temperature range,
The method is characterized in that welding defects are determined, thereby enabling more accurate inspection.

 Hereinafter, the present invention will be described in detail.

The present inventors have conducted a number of studies on seam welding of a drum can body in order to obtain a more reliable and highly reliable method for inspecting a welded part without performing conventional visual monitoring and subsequent airtightness testing of the can body. As a result of repeated experiments and studies, it has been found that if the welding defect can be determined by accurately measuring the temperature of the welded portion, it is optimal for determining the quality of the welded portion.

That is, FIG. 3 shows the inspection results of the can body welding portion performed by the present inventors. The welding current was changed, the temperature was measured each time, and the body welding portion at each temperature was cut out. It shows the state of the welded portion (the occurrence of cracks and peeling and its distribution) at the time of an Erichsen tester. The vertical axis indicates the temperature, and the horizontal axis indicates the axial position of the can body.

In FIG. 3, a mark .largecircle. Indicates a crack by the Erichsen test, and a mark X indicates peeling (peeling) by the Erichsen test, and indicates a good range of the hatched area. As can be seen from the figure, cracking and peeling occur concentrated in the portion A (top portion of the trunk) and the portion C (bottom portion of the trunk), and the central portion B does not peel unless the temperature becomes 750 ° C. or lower. Moreover, in part A, 14
Cracks occur at 00 ° C or higher, but peeling occurs at 820 to 850 ° C. This is considered to be unstable since the top part is affected by vibration of the mechanical system (air fluctuation), fluctuation in the speed of the material, and the like from the time when the top part is sandwiched between the electrode wheels.
Although a defect similar to that of the top part occurs at the bottom part, the degree is smaller than that of the top part.

From the above, there is a close relationship between the temperature of the weld and the welding defect, and if the welding temperature can be accurately measured during seam welding, the quality of the weld can be immediately determined based on this, and The top and bottom parts and the center part
It was found that the mechanism of defect generation is different and it is better to deal with them separately.

In addition, the temperature change of the seam welded portion is actually caused by a defect of the electrode ring for seam welding (dust adhesion, etc.), a change in the pressure applied to the electrode ring (particularly, a rise in temperature when the pressure decreases), a change in the current value, and the like. It is considered to be due to

The present invention has been completed based on such knowledge, and sets a temperature range in which a seam weld having no defect and having no problem in strength is set, and a temperature outside the set range is detected. Sometimes, 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, reference numeral 1 denotes a seam welded portion of a plate material constituting a body portion of a drum can, and 2a denotes a seam welded portion of the seam welded portion 1. A lower electrode wheel 2b disposed on the lower side is an upper electrode wheel movable in the vertical direction that sandwiches the seam welded portion 1 together with the electrode wheel 2a, and adjusts the pressing force by the operation of a pressing mechanism (not shown). All of these welding mechanisms are known, and other necessary members and mechanisms are omitted.

Reference numeral 3 denotes a temperature sensor which directs the position of the seam welded portion 1 during welding at the upper front in the welding direction of the electrode wheels 2a and 2b, for example, which has a very quick response and continuously detects the welding temperature with high accuracy. It is preferable to use a radiation thermometer that can perform the measurement. Spot position S to which the thermometer 3 points
The distance l between the temperature measuring point and the electrode wheel clamping position (welding point) is preferably as close to the welding point as possible, but is generally about 60 to 70 mm because of the structural limitations of the welding machine. If the directivity angle θ is less than 30 °, the emissivity is deteriorated, so that the directivity angle is set to 30 ° or more. However, the upper limit is desirably about 40 °.

Further, in FIG. 1, 4 is a photoelectric conversion unit, 5 is a control unit, and 6 is an optical fiber connecting the thermometer 3 and the photoelectric conversion unit 4.

In the present invention, when the temperature at the measurement point is detected by the thermometer 3 as light energy, this signal is sent to the photoelectric conversion unit 4 via the optical fiber 6 and converted into an electric signal.
Is input to A predetermined temperature range is set in the control unit 5, and a measured temperature value of the seam welded portion input from the thermometer is compared with the set temperature, and if the measured value is within the set range, the seam is left as it is. If the welding is continued and does not deviate from the range from the start to the end of the welding, the can body is sent to the next process without any defect in the weld. On the other hand, when the measured temperature value is out of the set range, the can body is taken out of the production line as a defective welded part by a command from the control unit 5, for example.

An example of the set pattern of the set temperature will be described with reference to FIG. In FIG. 2, first, the temperature control range is divided into a plurality of three parts, for example, a body tip part A, a center part B, and a rear end part C. Of course, the tip part and the rear end part are further divided, and furthermore, Fine-grained management is also possible. t _A ,
t _B and t _C are the above-mentioned front end A, center B, and rear end C, respectively.
Indicates the reference value of the lower limit of the set temperature, which varies depending on the steel plate to be welded or the welding machine. Further, the reference is set, the temperature measuring position, the angle of the radiation thermometer, and welding speed, electrode wheel pressure, since it is governed by the mechanical conditions such as welding current, t _A is usually in the constant welding conditions,
t _B and t _C are determined. Furthermore, the upper limit of the set temperature is almost determined once the lower limit is determined.
1.6 to 1.7 times is appropriate.

In FIG. 2, trunk length: 913 mm, tip A: 60 to 100 mm,
Table 1 shows specific welding conditions, materials, and temperature setting examples when the rear end portion B is 60 to 100 mm.

[Effects of the Invention] According to the inspection method of the present invention described above, the inspection accuracy of the seam welded portion of the can body is high and the reliability is also improved. The test can be omitted (the airtight test is only the product airtight test performed after the top and bottom plates are attached), and significant labor saving can be achieved.
Improve productivity of drums.

BRIEF DESCRIPTION OF THE 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 a reference temperature setting pattern in the present invention, and FIG. 3 is a graph showing the results of an experiment 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)

(57) [Claims] 1. A method of inspecting a drum body welded portion of a drum can, which is formed into a cylindrical shape in a drum can production line, and the opposite end portions are overlapped and welded to each other, in a position where the temperature is appropriately separated at an appropriate point during the welding. In addition to continuously detecting with a radiation thermometer, this detection value is divided into a plurality along the drum body axis direction and compared with a preset temperature range to determine welding defects. Inspection method for drum can welds.