Toyota Jidosha Kabushiki Kaisha

Matsushita Electric Industrial Co., Ltd.

Toyota Jidosha Kogyo Kabushiki Kaisha

Mikiji Suzuki

Takayuki Shimizu

Koji Fujii

Shuhei Ogura

Yoshikazu Tanaka

Makoto Ryudo

Masao Kawase

Yoshinori Tanaka

Hirohisa Sakai

Yukio Tamura

Satoshi Kuroiwa

Satoru Kiriyama

Yasuhiro Gotou

Hideya Kimura

Kiyoshi Shinki

Shinji Terada

Yuki Doi

Kouji Nomura

There are provided an electrode tip dressing apparatus and an electrode tip dressing tool for resistance welding, which are miniaturized by reducing a rotational driving-force of a dressing tool. By adjusting a curvature radius of a dressing portionof a dressing tool, a contact width, wherein a top electrode tipabuts to the dressing portionof the dressing tool, is adjusted from a rotational center of the dressing toolto the outer side of the dressing tool. Dressing work done with the dressing toolis thus made to be constant at the whole area of the dressing portion, from the rotational center of the dressing toolto the outer side of the dressing tool. Accordingly, excess dressing work, which brings decline of productivity, can be avoided, thus enabling to dress the top electrode tipwith the minimal dressing work. A rotational driving-power of the dressing toolis thereby reduced, enabling to labor-save and miniaturize the electrode tip dressing apparatus.

Electrode tip dressing apparatus and tool used therefor

Resistance welding machine control method

A spot welding method and apparatus having electrode tips one of which is driven by a servo motor. In the method and apparatus, it is determined whether or not an abnormal condition occurs. The abnormal condition includes (a) squeezing some obstacle between the electrode tip and a workpiece, (b) a temperature adhesion of the electrode tips with the workpiece, (c) uneven pressurizing of the workpiece by the electrode tips, (d) a weld nugget dispersion, and (e) a too large electric resistance between the electrode tips and the workpiece. When such abnormal condition is detected, some counter measure is taken to prevent or decrease the abnormal condition.

Spot welding control method and apparatus using a servo welding gun

A method for controlling a welding current in a resistance welder which phase-controls an A.C. power supply voltage by a thyristor to control the welding current to a target value. Prior to supplying the welding current, a test current is supplied to measure a power-factor angle of a load. A plurality of curves representing relations between the welding currents and control voltages to a phase-shift pulse generator for a plurality of power-factor angles of the load are presets and one of the curves is selected in accordance with the selected power-factor angle of the load. A variation of the A.C. power supply voltage is measured. A period of a pulse generated by the phase-shift pulse generator is controlled based on a value determined in accordance with the selected curve and the measured variation of the A.C. power supply voltage to control a firing angle of the thyristor.

Method for controlling welding current

A resistance spot welding method and apparatus wherein a weld can be judged to have an acceptable strength whether a splash (expulsion of weld metal) has occurred or not, provided that a maximum displacement (M) of a movable electrode to a fixed one is larger than a certain predetermined reference value (M.sub.L) or a rate (R) of the displacement at an initial stage is larger than a certain predetermined reference value (R.sub.L) which is defined between two certain predetermined reference values (R.sub.1, R.sub.E), by sensing the displacement and the rate thereof. Furthermore, when necessary, a weld is judged to have an acceptable indentation (I), as well, by sensing a position of the electrode at a specific point of time when a predetermined holding time has elasped from the time of de-energization of the welding current. Thus reliability of a spot welded joint is much improved and costly rejection of a welded product is considerably reduced.

Method and apparatus for judging quality of spot weld

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Okazaki, Japan

Mikiji Suzuki