JPH07214341A - Robot welding gun and method thereof - Google Patents

Abstract

PURPOSE:To prevent the wear of a supporting pin to pivotaly support the arm of a robot welding gun. CONSTITUTION:A pair of arms 2, 3 arranged with welding tip at the top end are connected to a pressing cylinder 6 and are opened/closed around a supporting pin 1. When at switching a first selector valve 15, a pressing cylinder 6 is extended by the high pressure air from an air supply source 13 and a proximity of the arms 2, 3 to closing end/opening end is detected by a stroke position detecting means, at switching a second selector valve 16, the exhaust from the pressing cylinder 6 is passed through a variable orifice 17. By this method, the impact applied to the supporting pin 1, when the arms 2, 3 reach closing end/opening end with lowering an extending/retracting speed of the pressing cylinder 6, is alleviated, the wear of the supporting pin 1 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of using a robot welding gun in which a pair of arms each having a welding tip at its tip is opened and closed with a fulcrum pin as an axis, and a work is clamped and pressed by the welding tip to perform welding. And a robot welding gun used to implement the method invention.

[0002]

2. Description of the Related Art Robot welding guns that perform spot welding by sandwiching and pressing the welded part of a workpiece with a pair of welding tips
A pair of arms having the welding tip at the tip is pivotally supported by a fulcrum pin so as to be openable and closable, and the arms are connected to a pressure cylinder to be opened and closed.

[0003]

By the way, in the above-mentioned conventional robot welding gun, since the driving speed of the pressure cylinder is constant, the moment the arm reaches the closed end and the welding tip comes into contact with the work or the arm opens. At the moment of reaching the end and stopping, a large impact force is generated and the fulcrum pin is worn early. Further, when the welding tip comes into contact with the work at the closed end of the arm, the work may be displaced by the impact force, a dent may be generated on the work, or the welding tip may be deformed to cause welding defects. There was a problem.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent wear of a fulcrum pin that pivotally supports an arm and prevent defective welding.

[0005]

In order to achieve the above-mentioned object, a method of using a robot welding gun according to a first aspect of the present invention is such that a pair of arms having a welding tip at their tips are opened and closed with a fulcrum pin as an axis. A method of using a robot welding gun for sandwiching and pressing a work with the welding tip to perform welding, wherein a closing speed and a closing speed of the arm when the arm reaches a closing end and / or an opening end. And / or reducing the opening speed.

According to a second aspect of the present invention, there is provided a robot welding gun in which a pair of arms having a welding tip at a tip thereof, a fulcrum pin for pivotally supporting the arms to open and close, a drive source for driving the arms to open and close, and an arm of the arms. The detection means for detecting the open / closed position, the speed adjustment means for adjusting the drive speed of the drive source, and the speed adjustment means are controlled on the basis of the output of the detection means so that the arm reaches the closed end and / or the open end. Control means for reducing the closing speed and / or the opening speed of the arm when the arm reaches the end.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 8 show an embodiment of the present invention. FIG. 1 is an overall configuration diagram of a robot welding gun, and FIG. 2 is FIG.
2-2 line enlarged sectional view of FIG. 3, FIG. 3 is a graph showing the operating speed of the pressure cylinder and the impact force applied to the fulcrum pin, and FIG.
5 is a graph showing the amount of wear of the fulcrum pin of the present invention, and FIGS. 7 and 8 are graphs showing the amount of wear of the conventional fulcrum pin.

As shown in FIG. 1, the robot welding gun G is provided with a pair of arms 2 and 3 pivotally supported at an intermediate portion by a fulcrum pin 1, and a work W is provided at the tip of each arm 2 and 3. Welding tips 4, 5 for spot welding by sandwiching and pressing
Are provided respectively. An output rod 8 ₁ of a pressurizing cylinder 6 as a drive source provided at the base end of one arm 2 is connected to the base end of the other arm 3 via a link 7.
The piston 8 inside the pressure cylinder 6 fixed to the output rod ₈₁ is slidably fitted in the output rod ₈₁ side of the piston 8 and the opposite output rod 8 first chamber ₁ side 9 and The second chamber 10 is defined. When high pressure air is supplied to the first chamber 9, the pressurizing cylinder 6 contracts and the arms 2 and 3 open, and when high pressure air is supplied to the second chamber 10, the pressurizing cylinder 6 extends and the arms 2 and 3 move. Close.

A robot controller 11 for controlling the welding robot is connected to a pressure controller 12 as control means for controlling the operation of the pressure cylinder 6. The air supply source 13 is connected to the first chamber 9 and the second chamber 10 of the pressurizing cylinder 6 via the pressure control valve 14 and the first switching valve 15, and the first switching valve 15 is connected to the second switching valve 16. It is connected to the variable aperture 17 via the. The pressure cylinder 6 is provided with a stroke position detecting means 18 for detecting the position of the output rod 8 ₁ (that is, the amount of expansion and contraction of the pressure cylinder 6). The pressure controller 12 is the robot controller 1
The first switching valve 15 and the second switching valve 16 are controlled based on the signals from the 1 and the stroke position detecting means 18.
The second switching valve 16 and the variable throttle 17 constitute the speed adjusting means of the present invention.

As shown in FIG. 2, provided on one arm 2.
A pair of brackets 2₁, 2₁And on the other arm 3
Bracket 3₁And are pivotally supported by the fulcrum pin 1. Bu
Racket 2₁, 2₁On the outside of the pair of collars 19,19
Are fitted, and the collars 19 and 19 of the fulcrum pin 1
Flange 1 formed at one end₁And the strike fixed to the other end
It is prevented from coming off by the upper plate 20. Fulcrum pin
1, bracket 2₁, 2 ₁, 3₁And color 19, 19
A plurality of bearing metals 21 ... Are interposed on the sliding surface between them.
Lubricate the bearing metal 21 ... Inside the fulcrum pin 1.
Grease reservoir 1 for₂Is formed.

Next, the operation of the embodiment of the present invention having the above construction will be described.

When the solenoid of the first switching valve 15 is excited by the command from the pressurizing controller 12 and switched in the direction of arrow a, the high pressure air from the air supply source 13 is supplied to the second chamber 10 to pressurize the cylinder. 6 extends, arm 2,
3 closes. At this time, the second switching valve 16 is at the position shown in the figure, and the exhaust gas from the first chamber 9 of the pressurizing cylinder 6 is exhausted to the atmosphere without passing through the variable throttle 17.
The extension speed of, that is, the closing movement speed of the arms 2 and 3 becomes a normal speed.

When the stroke position detecting means 18 of the pressurizing cylinder 6 detects that the arms 2 and 3 are close to the closed end, the solenoid of the second switching valve 16 is excited by a command from the pressurizing controller 12. And the exhaust from the first chamber 9 of the pressurizing cylinder 6 is switched to the direction of the arrow b.
It will be discharged to the atmosphere through 7. As a result, the extension speed of the pressurizing cylinder 6 decreases and the closing speed of the arms 2 and 3 is reduced. Therefore, the impact when the pair of welding tips 4 and 5 clamps and presses the welded portion of the work W is impacted. The force is relieved, which prevents the occurrence of welding failure due to the displacement of the work W during welding and the deformation of the welding tips 4 and 5.

As is apparent from comparison between FIGS. 3 and 4, in the present embodiment shown in FIG. 3, the extension speed of the pressure cylinder 6 is P.
Since it is decelerated at the point, the impact force applied to the fulcrum pin 1 when the welding tips 4 and 5 clamp and press the work W at the point Q is much less than the impact force of the conventional one shown in FIG. .

When welding is completed, the pressure controller 12
The solenoid of the first switching valve 15 and the solenoid of the second switching valve 16 are both demagnetized and switched in the directions of the arrows a ′ and b ′ respectively by the command from the high pressure air from the air supply source 13 in the first chamber 9 And the pressure cylinder 6 contracts, and the arms 2 and 3 open. At this time, since the exhaust gas from the second chamber 10 of the pressurizing cylinder 6 is exhausted to the atmosphere without passing through the variable throttle 17, the contracting speed of the pressurizing cylinder 6,
That is, the opening speed of the arms 2 and 3 becomes a normal speed.

When the stroke position detecting means 18 of the pressurizing cylinder 6 detects that the arms 2 and 3 are close to the open end, the solenoid of the second switching valve 16 is excited by a command from the pressurizing controller 12. The exhaust gas from the second chamber 10 of the pressurizing cylinder 6 is switched to the direction of the arrow b and is exhausted to the atmosphere through the variable throttle 17. as a result,
Since the contraction speed of the pressurizing cylinder 6 decreases and the opening speed of the arms 2 and 3 is reduced, the impact force when the arms 2 and 3 stop at the opening end is alleviated.

Thus, no great impact force is generated when the arms 2 and 3 stop at the closed end and the open end, so that the fulcrum pin 1 that pivotally supports the arms 2 and 3 is less worn. . Moreover, the work W is sandwiched between the welding tips 4 and 5.
When pressurizing, the work W is prevented from being displaced and dented, and the welding tips 4 and 5 are prevented from being deformed or damaged. Also, based on the output of the stroke position detecting means 18 at the closed ends of the arms 2 and 3, the welding tips 4 and
It is possible to detect wear and dropout of No. 5.

FIGS. 5 and 6 show the amount of wear along the four bus bars A to D spaced at 90 ° intervals in the circumferential direction at the X and Y portions of the fulcrum pin 1 of this embodiment. As is apparent from comparison with the conventional example of FIGS. 7 and 8 corresponding to the same figure, it is clear that the amount of wear is significantly reduced due to the deceleration of the opening / closing speed at the closed and open ends of the arms 2 and 3. To be understood.

Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various design changes can be made.

For example, in the embodiment, the operating speed of the pressurizing cylinder 6 is reduced at both the closed end and the open end of the arms 2 and 3, but the pressurizing cylinder is provided at either the closed end or the open end. Even if the operating speed of 6 is reduced, it can contribute to the reduction of the wear amount of the fulcrum pin 1.

[0022]

As described above, according to the invention described in claim 1, when the arm that opens and closes about the fulcrum pin reaches the closing end and / or the opening end of the arm. Since the impact velocity is suppressed by reducing the closing velocity and / or the opening velocity, not only can the abrasion of the fulcrum pin due to the impact force be prevented and the service life be extended, but also the work position shift and welding tip It is possible to prevent deformation and avoid the occurrence of defective welding.

According to the invention described in claim 2,
Since the drive speed of the drive source for opening and closing the arm is adjusted on the basis of the output of the detection means for detecting the open / closed position of the arm, when the arm reaches the closed end and / or the open end, It is possible to reliably reduce the closing speed and / or the opening speed of the arm.

[Brief description of drawings]

[Figure 1] Overall structure of robot welding gun

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

FIG. 3 is a graph showing the operating speed of the pressure cylinder and the impact force applied to the fulcrum pin.

FIG. 4 is a graph showing a conventional example corresponding to FIG.

FIG. 5 is a graph showing the amount of wear of the fulcrum pin.

FIG. 6 is a graph showing the amount of wear of the fulcrum pin.

FIG. 7 is a graph showing the amount of wear of a conventional fulcrum pin.

FIG. 8 is a graph showing the amount of wear of a conventional fulcrum pin.

[Explanation of reference symbols] 1 fulcrum pin 2 arm 3 arm 4 welding tip 5 welding tip 6 pressurizing cylinder (driving source) 12 pressurizing controller (control means) 16 second switching valve (speed adjusting means) 17 variable throttle (speed adjusting) 18) Stroke position detecting means (detecting means) W work

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiro Suematsu 1907 Hirata-cho, Suzuka-shi, Mie Honda Motor Co., Ltd. Suzuka Factory

Claims (2)

[Claims] 1. A pair of arms (2, 3) having welding tips (4, 5) at their tips are opened and closed around a fulcrum pin (1) as an axis, and a work (W is formed by the welding tips (4, 5). ) Is sandwiched / pressurized and welded, the robot welding gun being used, wherein the arm (2, 3) of the arm (2, 3) reaches the closed end and / or the open end. A method of using a robot welding gun characterized by reducing the closing speed and / or the opening speed. 2. A pair of arms (2, 3) having welding tips (4,5) at their tips, a fulcrum pin (1) for pivotally supporting the arms (2, 3) to open and close, and an arm (2). , 3) to open / close, a detecting means (18) to detect the open / close position of the arms (2, 3), and a speed adjusting means (16, 16) to adjust the drive speed of the drive source (6). 17) and the speed adjusting means (16, 17) based on the output of the detecting means (18).
Control means (12) for controlling the closing speed and / or the opening speed of the arm (2, 3) when the arm (2, 3) reaches the closing end and / or when the arm (2, 3) reaches the opening end.
A robot welding gun characterized by having and.