JP2018089638A - Spot welding electrode polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the jamming of sawdust when the leading end of an electrode by a rotating blade, thereby to avoid a cutting failure and to shorten a processing time and improve the finished article quality.SOLUTION: A spot welding electrode polishing method for cutting a spot welding electrode W by pushing the spot welding electrode onto a rotating blade 3 comprises: the step (2) of causing the blade 3 to bite into the leading end of the electrode W; and the present cutting step (3) of making the applied pressure of the electrode W lower than that of the blade biting step (2), and the step of making the rotation number of the blade 3 higher than that of the blade biting step (2) thereby to cut the electrode.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a method for polishing a spot welding electrode.

  A large amount of pressure is applied to the electrode for spot welding and a large current flows at the time of welding, and the electrode is subjected to high temperatures. Or stick. If this is left unattended, it will cause welding failure, so it is necessary to periodically shape the tip of the electrode into a predetermined shape by cutting or the like.

  For example, in an automatic welding facility that automatically welds a workpiece by a welding robot, an electrode polishing apparatus is disposed in the vicinity of the welding robot, and the tip of the electrode is automatically shaped every time welding is performed a predetermined number of times. For example, Patent Document 1 below discloses an electrode polishing apparatus that rotates a cutter holder provided with a blade (cutter) and presses the tip of an electrode against the blade to cut the electrode. The cutter holder is provided with a discharge groove (notch groove) adjacent to the front side in the rotational direction of the blade, and the cutting waste that has entered the discharge groove is discharged radially outward by centrifugal force.

JP 2002-292472 A

  In the conventional electrode polishing apparatus, the electrode is cut by pressing the electrode with a constant pressure against the blade rotated at a constant rotation speed. In such an electrode polishing apparatus, the cutting time can be shortened by increasing the blade rotation speed and the electrode pressing force to increase the amount of electrode cutting. However, in this case, cutting waste is clogged in the discharge groove provided in the cutter holder, which may cause cutting defects. In addition, the processing quality at the tip of the electrode may be lowered simply by increasing the rotation speed of the blade or the applied pressure of the electrode.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent clogging by avoiding clogging of cutting waste when polishing the tip of an electrode with a rotating blade, and to reduce machining time and improve machining quality.

  In order to achieve the above object, the present invention provides a blade biting process in which the tip of a spot welding electrode is pressed against a rotating blade to bite the blade into the tip of the electrode; And a main cutting step of cutting the electrode by making the rotational speed of the blade higher than that of the blade biting step.

  Thus, in the electrode polishing method of the present invention, the blade rotation speed and the applied pressure of the electrode are different between the blade biting process in which the blade bites into the electrode tip and the subsequent cutting process in which the electrode tip is cut thereafter. Let Specifically, in the blade biting process, in order to make the blade easily bite into the electrode, the rotation speed of the blade is decreased and the pressure applied to the electrode is increased. And if the blade bites into the tip of the electrode at a predetermined depth, no further biting is necessary, so in the subsequent cutting process, the electrode pressing force can be made lower than in the blade biting process to suppress cutting resistance. it can. In this way, cutting the tip of the electrode only in the required amount, quickly and cleanly by cutting at a high speed with the cutting speed reduced and higher than the blade biting process. Can do. In addition, as described above, after cutting the blade tip into the tip of the electrode at a low rotational speed and high pressurization, cutting the tip of the electrode at a high rotational speed and low pressurization to finely cut the cutting waste Therefore, it is possible to avoid clogging of cutting waste and cutting defects accompanying this.

  As described above, according to the method for polishing a spot welding electrode according to the present invention, when the tip of the electrode is polished with a rotating blade, cutting dust clogging is prevented to avoid cutting defects, and processing time is shortened. In addition, the processing quality can be improved.

It is a top view of a rotary cutting tool. It is a perspective view of a rotary cutting tool. It is a perspective view of a blade. It is a disassembled perspective view of a rotary cutting tool. It is sectional drawing in the XX line of FIG. It is a flowchart which shows the procedure of the grinding | polishing method of the electrode for spot welding.

  Embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a case where a pair of electrodes provided on a C-type gun for performing direct spot welding is simultaneously polished by an electrode polishing apparatus is shown.

  The electrode polishing apparatus has a rotary cutting tool 1 shown in FIGS. 1 and 2. The rotary cutting tool 1 is rotationally driven by a drive motor (not shown). In the present embodiment, the drive motor is a servo motor that can control the rotation speed and the rotation direction.

  The rotary cutting tool 1 has a holder 2 and a blade 3 held by the holder 2. In the present embodiment, the plurality of blades 3 are arranged at equal intervals in the rotation direction of the rotary cutting tool 1, and in the illustrated example, the two blades 3 are arranged with a phase difference of 180 °. As shown in FIG. 3, arc-shaped blade portions 3 a and 3 a corresponding to the tip shape of the electrode W are provided on both upper and lower sides of each blade 3.

  As shown in FIG. 4, the holder 2 is composed of two halved holders 2a and 2a having the same shape divided into two in the diameter direction. Each half holder 2a has a substantially semi-cylindrical shape. On both the upper and lower surfaces of the holder 2 are provided concave portions 2b into which the tips of the electrodes W can be fitted. The concave surface portion 2 b is provided with a discharge groove 2 c for discharging cutting waste to the outside in the radial direction of the holder 2. The discharge groove 2c is adjacent to the front side in the cutting rotation direction of each blade 3 (the direction of arrow A in FIG. 1). The blade 3 is attached to the holder 2 by fixing the half holders 2a, 2a with bolts 4 in a state where the blade 3 is sandwiched between the half holders 2a, 2a.

  The rotary cutting tool 1 is rotated in the direction A in FIG. 1 by a drive motor. In this state, the rotary cutting tool 1 is sandwiched from above and below by a pair of electrodes W and W as shown in FIG. Is pressed against the blade portion 3a of the blade 3, the tip of each electrode W is cut and shaped into a predetermined shape. This operation is performed through (1) blade contact process, (2) blade biting process, (3) main cutting process, and (4) finishing process. As shown in FIG. 6, these steps are continuously performed while controlling the pressing force of the electrode W and the rotational speed of the rotary cutting tool 1. Hereinafter, each process will be described in detail.

(1) Blade Contact Process In the blade contact process, each electrode W is brought into contact with the blade 3 at a relatively low pressure while the rotary cutting tool 1 is rotated at a relatively low speed. In this way, at the start of cutting (when the electrode W and the blade 3 are in contact), the electrode W can be soft-touched to the blade 3 by setting the rotation speed and pressure to be low, so that the blade 3 is damaged. Can be prevented.

(2) Blade biting process When a predetermined time has elapsed with the rotational speed and the applied pressure in the blade contact process, the applied pressure of the electrode W is increased while maintaining the rotational speed of the rotary cutting tool 1. Thus, by cutting the tip of the electrode W at a low rotational speed and high pressure, the bite of the blade 3 into the tip of the electrode W is promoted, so that a predetermined bite amount can be achieved in a short time. it can. The rotational speed of the rotary cutting tool 1 may be different from the blade contact process, and may be higher than the blade contact process, for example, but is set lower than the rotational speed in the main cutting process described later.

(3) Main cutting process After that, when a predetermined time has passed with the rotational speed and the applied pressure in the blade biting process, the process proceeds to the main cutting process. Since the blade 3 sufficiently bites into the tip of the electrode W by the blade biting process, it is not necessary to bite the blade 3 into the tip of the electrode W any more in this cutting process. Therefore, in this cutting process, if the pressing force of the electrode W is lowered and the blade 3 is rotated while substantially maintaining the relative positional relationship between the electrode W and the blade 3 (the positional relationship of the electrode W in the pressurizing direction). Good. Thus, the cutting resistance can be suppressed by not allowing the blade 3 to bite into the tip of the electrode W in this way, and in this state, the rotational speed of the rotary cutting tool 1 is increased and cutting is performed at a high speed. Only the required amount of the tip of W can be cut quickly, cleanly and reliably. In addition, this cutting process is the longest process in each process of a grinding | polishing operation | work, for example, occupies 50% or more of the total operation time.

  As described above, after cutting the blade 3 sufficiently into the tip of the electrode W by cutting at a low rotational speed and high pressure in the blade biting process of (2), By cutting at a rotational speed and low pressure, the cutting waste can be finely divided. In particular, as in this embodiment, the amount of cutting per blade 3 is reduced by cutting each electrode W with the blades 3 arranged at a plurality of locations (two locations in the illustrated example) at equal intervals in the rotation direction. Therefore, the cutting waste can be further finely divided. Thereby, cutting waste becomes easy to be discharged | emitted from the discharge groove | channel 2c of the rotary cutting tool 1 with the centrifugal force by rotation of the rotary cutting tool 1, or the air from the air blow apparatus which is not shown in figure. Therefore, a situation in which cutting waste is clogged in the discharge groove 2c is avoided, and cutting failure due to cutting clogging can be prevented.

(4) Finishing process After that, when a predetermined time has elapsed with the rotational speed and the applied pressure in the main cutting process, the rotational speed is increased and the applied pressure is decreased as compared with the main cutting process. In this manner, by cutting the tip of the electrode with a low pressure and high rotation speed, burrs and the like generated by this cutting process can be removed, so that the tip of the electrode can be finished smoothly. Moreover, the tip of the electrode can be finished more smoothly by separating the electrode W from the blade 3 while the blade 3 is rotated at a high speed as described above.

  By performing the steps (1) to (4) as described above, the processing time can be significantly reduced as compared with the conventional electrode polishing method in which the rotation speed and the applied pressure are constant. For example, a polishing operation that takes about 3 seconds per electrode in the conventional electrode polishing method can be performed in about 1 second in the electrode polishing method of the present embodiment. In this case, since the rotation speed and the applied pressure change every short time, it is not easy to cut the electrodes stably. In this embodiment, each electrode is cut using a plurality of blades 3 arranged at equal intervals in the rotation direction. Therefore, even when the number of rotations and the applied pressure are changed as described above, the electrodes are stably provided. Can be cut.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, if there is no problem of damage to the blade 3, (1) the blade contact step may be omitted, and (2) the cutting may be started at the rotational speed and the applied pressure in the blade biting step. Moreover, in said embodiment, if the finishing after this cutting process is unnecessary, (4) Finishing process may be abbreviate | omitted.

  Moreover, the structure of the rotary cutting tool 1 is not restricted above. For example, in the above-described embodiment, the case where the blade portion 3a of the blade 3 is provided on the upper surface and the lower surface of the rotary cutting tool 1 and the pair of electrodes W and W are cut at the same time is shown. The blade 3a may be provided only on one surface of the tool 1.

1 Rotating Cutting Tool 2 Holder 3 Blade 4 Bolt W Electrode

Claims (1)

A blade biting step in which the tip of the electrode for spot welding is pressed against the rotating blade to bite the blade into the tip of the electrode;
An electrode polishing method comprising: a main cutting step of cutting the electrode while lowering the pressing force of the electrode than the blade biting step and increasing the rotation speed of the blade higher than the blade biting step.

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