JP2002028788A - Electric spot welding gun - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To make it possible to reduce the size of the entire electric spot welding gun. A servo motor includes a motor housing mounted on a gun body and the motor housing.
And a hollow rotor 5c rotatably supported in the motor housing 5a. The feed screw mechanism 6 includes a screw rod 6 connected to the hollow rotor 5c and rotating. And a nut 6b screwed into the screw rod 6 to move the upper chip 8 forward and backward with respect to the lower chip 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric spot welding gun for opening and closing one electrode tip constituting a pair of electrode tips with respect to the other electrode tip via a feed screw mechanism under the action of a servomotor. About.

[0002]

2. Description of the Related Art Conventionally, an electric spot welding gun of this type is provided with an encoder for detecting a rotation angle of a rotor constituting a servomotor, and a signal from the encoder is inputted to a gun controller. I have. Then, from the rotation speed of the rotor and the pitch of the feed screw mechanism,
Determine the position of one electrode tip, open the one electrode tip to a required open position after spot welding the work, and until the one electrode tip comes into contact with the other electrode tip after dressing the electrode tip, etc. It is closed so that a change in tip length can be detected from the position of the one electrode tip at this time.

[0003]

SUMMARY OF THE INVENTION The present invention relates to an electric spot welding gun of this type, and an object of the present invention is to provide an electric spot welding gun which can be easily made compact. .

[0004]

An electric spot welding gun according to the present invention has a pair of electrode tips, and one of the electrode tips is rotated by a feed screw mechanism connected to a servomotor. The servomotor is opened and closed with respect to a chip, and the servomotor includes a motor housing mounted on a gun body, a stator fixed in the motor housing, and a hollow rotor rotatably supported in the motor housing. The feed screw mechanism includes a screw rod connected to the hollow rotor and rotating, and a nut screwed to the screw rod to advance and retreat the one electrode tip with respect to the other electrode tip. ing. Therefore, the electric spot welding gun can be easily shortened in the axial direction, and the overall configuration can be made compact.

[0005]

FIG. 1 is a side view of a robot R equipped with an electric spot welding gun G according to an embodiment of the present invention. The spot welding gun G is attached to the wrist Ra of the operation end of the robot R for welding the work W.

The spot welding gun G has a gun body 2, which is supported by a gun support bracket 1 fixed to a wrist Ra via a guide bar 1a so as to be capable of performing an equalizing operation in a vertical direction. ing. Gun body 2
, A C-shaped yoke 3 extending downward is attached, and a lower tip (the other electrode tip) 4 as a fixed electrode tip is attached to a lower end of the C-shaped yoke 3.

On the upper surface of the gun body 2, a servo motor 5 is mounted, and a rod 7 which is vertically moved by a servo screw 5 via a feed screw mechanism 6 (see FIG. 2) which will be described later.
It protrudes below the gun body 2. An upper tip (one electrode tip) 8 which is a movable electrode tip is attached to a lower end of the rod 7 so as to face the lower tip 4, thereby forming a C-shaped spot welding gun G. The spot welding gun G is transmitted from the robot controller 9 to the gun controller 1.
0 is driven and controlled.

As shown in FIG. 2, the servo motor 5 includes a motor housing 5a erected on the gun body 2, a stator 5b fixed in the motor housing 5a, and a hollow hollow shaft supported in the motor housing 5a. And a rotor 5c. The rod 7 is inserted into the rotor 5c through the guide sleeve 2a in the gun body 2.

The upper part of the rod 7 is formed hollow,
A screw 6a fixed to the upper end of the rotor 5c is inserted into the hollow portion of the rod 7, and a nut 6b screwed to the screw 6a is fixed to the upper end of the rod 7. By means of these screw rods 6a and nuts 6b, the rotor 5
feed screw mechanism 6 for converting the rotation of c into vertical movement of rod 7
Is configured.

A pair of upper and lower angular bearings 5d and 5e are extrapolated above the rotor 5c, and the rotor 5c has a shoulder 5f which contacts the lower end surface of the inner race of the lower angular bearing 5e. The shoulder 5g which is formed and abuts on the upper end surface of the outer race of the upper angular bearing 5d is formed on the motor housing 5a.
Is formed. Tightening nut 5 on the upper end of rotor 5c
h is screwed in, the angular bearings 5d and 5e are pressurized by the tightening nut 5h, and the rotor 5c
The backlash in the axial direction is removed.

An encoder 11 is mounted on the upper end of the motor housing 5a via a stay 11b. An input shaft 11a of the encoder 11 is connected to the rotor 5c so that the rotation angle of the rotor 5c can be detected. Is configured. The input shaft 11a of the encoder 11 is
The rotor 5c is connected to the rotor 5c through a cushion member 12 that absorbs an axial shock acting through the rotor 5c.

The spot welding gun G thus configured
Will be described below.

First, the spot welding gun G is
Is moved to each hit point position of the work W. When the spot welding gun G arrives at each hitting position, a pressurizing command is transmitted from the robot controller 9 to the gun controller 10, and the servo motor 5 is controlled by the gun controller 10. As a result, the upper chip 8 is moved downward from a predetermined open position, and when the upper chip 8 comes into contact with the work W by the downward movement of the upper chip 8, the gun body 2 is thereafter moved by the contact reaction force. Move up to 1.

For this reason, the lower chip 4 comes into contact with the work W, and the work W is sandwiched between the upper and lower chips 4 and 8 and pressed. In this state, electricity is supplied between the two chips 4 and 8, and the respective spots of the work W are spot-welded.

On the other hand, a signal from the encoder 11 is input to the gun controller 10, and the position of the upper chip 8 is determined from the rotation angle of the rotor 5c and the pitch of the feed screw mechanism 6. Therefore, after the spot welding, the upper chip 8 is moved up to a position corresponding to the predetermined open position under the action of the servomotor 5.

[0016]

In the electric spot welding gun according to the present invention, the servo motor includes a motor housing mounted on the gun body, a stator fixed in the motor housing, and a rotatable shaft in the motor housing. A hollow rotor that is supported, wherein the feed screw mechanism is connected to the hollow rotor and rotates, and a screw rod is screwed into the screw rod, and the one electrode tip is attached to the other electrode tip. A reciprocating nut. Therefore, the electric spot welding gun can be easily shortened in the axial direction, and the overall configuration can be made compact.

[Brief description of the drawings]

FIG. 1 is a side view of a robot equipped with an electric spot welding gun according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG.

[Explanation of symbols]

2 ... Gun body 4 ... Lower tip 5 ... Servo motor 5a ... Motor housing 5b ... Stator 5c ... Rotor 6 ... Feed screw mechanism 6a ... Screw rod 6b ... Nut 7 ... Rod 8 ... Upper tip 11 ... Encoder G ... Spot welding gun R ... robot

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hitoshi Sasaki 1-10-1 Shinsayama, Sayama City, Saitama Prefecture Honda Engineering Co., Ltd. (72) Inventor Hiroshi Iwasaki 19 Matsuyamacho, Moka City, Tochigi Prefecture Honda Motor Co., Ltd. F-term in Tochigi Works (reference) 4E065 AA08 BA06

Claims (1)

[Claims] 1. An electric spot welding gun comprising a pair of electrode tips, wherein one of the electrode tips is opened and closed with respect to the other electrode tip under the rotation of a feed screw mechanism connected to a servomotor. The servo motor comprises: a motor housing mounted on a gun body; a stator fixed in the motor housing; and a hollow rotor rotatably supported in the motor housing. The electric mechanism comprises: a screw rod that is connected to the hollow rotor and rotates; and a nut that is screwed with the screw rod and that advances and retreats the one electrode tip with respect to the other electrode tip. Type spot welding gun.