JPH0773792B2 - Spot welding electrode welding method - Google Patents

Description

The present invention relates to a resistance welding test method relating to electric resistance welding.

(Prior Art) Electric resistance welding such as spot welding is one in which a pair of upper and lower electrodes facing each other are used to press an object to be welded, and welding is performed by applying an electric current for a predetermined time, and the production section is widely used. In this case, as shown in FIG. 2, the material to be welded S is the electrode holder.
It is welded while being pressed against the electrodes 1 and 2 that are fixed to 3 and 4, but a large current flows locally due to excessive welding current, partial contact of the electrode, uneven wear of the electrode, etc. In some cases, the electrode and the material to be welded adhere to each other and cannot be easily separated, that is, the electrode may be welded. Further, particularly in various surface-treated steel sheets including galvanized steel sheets, electrode welding is likely to occur because the plated metal on the steel sheet surface and the electrode copper are alloyed.

When electrode welding occurs on the production line, a series of welding work operations are stopped, or the electrode comes out of the holder to cause water leakage, and at the same time, subsequent welding becomes a blanking state, which is a serious problem. Therefore, when applying the material to be welded to the production line, it is necessary to investigate the proper welding current range in advance and to accurately obtain the electrode welding current value (welding limit value).

(Problems to be solved by the invention) However, in the conventional electrode welding determination method, the test piece fixed to the electrode is grasped by pliers or another jig and twisted, or the test piece is peeled by hitting with a small hammer, and measurement at that time is performed. It was only a qualitative determination method such as determining whether or not the electrode was welded by the person's touch. Therefore, it is difficult to set the optimum welding current value because the welding limit value often changes to about 2000A to 5000A when the measurer is changed or repeated experiments are performed. Therefore, there has been a demand for the development of a quantitative measuring method of the welding force, which is easy to handle and does not vary among measuring persons.

On the other hand, as means for solving these welding problems, for example, JP-A-50-55559, JP-A-57-7389 and JP-A-57-56178 are known, but in the former two cases, Is a method of applying (spraying) an anti-adhesion agent to the electrode or the material to be welded to make it difficult to cause welding, and the latter is a means to electrically detect whether or not the opening of the sequence after welding has worked normally. . Therefore, it is clear that each of the exemplified publications is not a means for measuring the welding force accurately and quantitatively in a laboratory or in a production line.

An object of the present invention is to solve the problems of the conventional electrode welding determination method, and to provide a quantitative and accurate welding force measuring method.

(Means for Solving the Problems) The present invention for solving the above problems includes: (1) When a test material to be welded after spot welding is welded to at least one of a pair of opposing upper and lower electrodes, a bit with slits Apply the torque by sandwiching the test material with
And a welding force measuring method for spot welding electrodes, characterized by measuring a torque value required for peeling the test material to be welded from the electrode, (2) The test material to be welded after spot welding is a pair of upper and lower surfaces facing each other. When welded to at least one of the electrodes, the test material is sandwiched by a bit with a slit, torque is applied to a part of the test material, and the torque value required to peel the test material to be welded from the electrode is measured. A characteristic method is a welding force measuring method for a spot welding electrode.

(Operation) The present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. When the test material S to be welded adheres to the electrode 1 after the spot welding, in order to judge whether or not the degree of the adherence is a level that should be judged to be welding, the center point P of the adherence is used as the point of action and The test material S is provided by a bit 5 provided with a slit for sandwiching the test material S.
Torque is applied as indicated by the arrow A or the arrow B by sandwiching.
Although not shown in FIG. 1, the bit 5 is fixed to a well-known device (for example, a torque wrench or a torque driver) capable of measuring torque, and the torque required to peel the test material S from the electrode 1 is fixed. Be prepared to measure the value. It is appropriate to set the welding force to the maximum torque value (kg-cm) until the test piece peels off, but the torque value to determine electrode welding is appropriate depending on the type of welded material, plate thickness, shape The reference value may be set. However, at least it should be set to a value smaller than the welding state (welding force) that causes electrode omission (electrode omission from the electrode holder).

FIG. 3 shows a detailed mode in the case where a torque is applied as shown by an arrow A among the modes described in FIG. 1, and FIG. 4 shows a detailed mode as indicated by an arrow B in the mode described in FIG. A detailed mode in the case where the torque is applied on the central axis of the bit 5 is shown.

The shape of the bit 5 with a slit that applies a torque to the test material S to be welded is not limited to the shape illustrated in FIGS. 3 and 4, and may be such that it surrounds the electrode as shown in FIG. It does not matter if the shape of the bit sandwiching the material to be welded, or the sectional shape is circular or elliptical as shown in FIG. Further, the bit 5 with slit is fixed to the torque measuring device in a detachable state, and is appropriately exchanged and used according to the shape and size of the material to be welded, especially the slit width.

Although FIGS. 1, 3, and 4 exemplify the case where the test material to be welded is welded to the upper electrode, the same applies when the lower electrode is welded or when the upper and lower electrodes are welded simultaneously. It goes without saying that there is no problem with the measurement of.

As described above, a bit provided with a slit for sandwiching a test material to be welded is fixed to a known device capable of measuring a torque value, and the electrode welding force is measured by a measurement method in which torque is applied via this bit. The torque value can be measured accurately and quantitatively. As a result, the electrode welding current value (welding limit value) in the investigation of the proper welding current range has no variation among the operators, and the variation width of the obtained welding current value also decreases, so the set current value on the production line is reduced. Can easily adjust to the optimum current value, improving productivity,
It plays an extremely important role in production control and research and development.

(Examples) Examples of spot welding electrode welding force measurement according to the present invention will be described below.

The test material to be welded is an electrogalvanized steel plate with a plate thickness (t) of 0.8 mm 2
Two sheets of 0/20 (g / m ² ) were used in a stack. The welding conditions are summarized below.

Welding machine: Stationary spot welding machine 60kvA Electrode shape: Dome type (6φ, 40R), D = 16mmφ Pressurizing force: 250kg Energizing time: 10 cycles Welding current: Change Specimen shape: 30 * 50mm (dot at center) Welding force Measurement: A ... Torque wrench: Inventive method B ... Torque driver: Inventive method Note: The same bit is used for both torque wrench and torque driver Bit slit depth = 15mm Bit slit frontage = 10mm Bit slit width = 2mm Table The welding conditions and welding results are shown in Fig. 1, together with the welding determination results of the conventional method and the welding force (torque value) measurement results and welding determination results of the method of the present invention.

In the conventional method, the current value determined to be welding was 12,100 for each measurer.
A, 14,300A, 15,600A, the variation width is 3,500A
Met. On the other hand, in the method of the present invention, when the welding was set to 20 kg-cm or more, both the methods A and B of the present invention were 13,400 A, showing no difference.

(Effects of the Invention) As is clear from the results shown in Table 1 above, the method for measuring the welding force of the spot welding electrode of the present invention is simple in handling, does not require the skill of the measurer, and the electrode welding current value (welding limit) value)
Can accurately set the welding current value on the production line and plays an extremely important role in improving productivity, production control (quality improvement), and R & D efficiency. However, it has a great effect on industrial use.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the method of the present invention, FIG. 2 is a side view showing an embodiment of a conventional welding situation, and FIG. 3 is a perspective view showing one embodiment of an apparatus used in the method of the present invention. FIG. 4 is a perspective view showing another embodiment of the apparatus used in the method of the present invention, FIG.
FIG. 6 is a perspective view showing an example of an apparatus used in the method of the present invention,
The figure is a perspective view showing another example of the apparatus used in the method of the present invention. 1,2 ... Electrodes, 3,4 ... Electrode holders, 5 ... Bits with slits (the tip of the torque measuring machine).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunihiro Hayashida 5-10-1 Fuchinobe, Sagamihara City, Kanagawa Pref., Second Research Laboratory, Nippon Steel Corporation (72) Inventor Kaho Kajimoto, Kanagawa Ward, Yokohama City, Kanagawa Prefecture 2 Takaramachi Nissan Motor Co., Ltd. (56) Reference JP-A-55-144906 (JP, A)

Claims (2)

[Claims] 1. When a test material to be welded after spot welding is welded to at least one of a pair of upper and lower electrodes facing each other, a bit with a slit sandwiches the test material to apply torque, and the test material to be welded is sandwiched. A method for measuring a welding force of a spot welding electrode, which comprises measuring a torque value required for peeling from an electrode. 2. When a test material to be welded after spot welding is welded to at least one of a pair of upper and lower electrodes facing each other, the test material is sandwiched by a bit with a slit to apply a torque to a part of the test material, and A method for measuring a welding force of a spot welding electrode, which comprises measuring a torque value required for peeling a welding test material from an electrode.