JP2002346756A - Electric welding gun - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain high torque and to improve working efficiency. SOLUTION: To a rotor 46, an annular magnet 42 is fixed and the inner diameter D of the magnet 42 is set to the same sizes with the thickness t regardless of the power output of a servo-motor 34 and on the other hand, the size S in the axial direction of the rotor 46 in the magnet 42 is set almost in proportion to the output of this servo-motor 34. The output of the servo-motor 34 is set as much as two times the output of the regulated servo-motor, and the size S in the axial direction of the magnet 42, is set as much at two times the size S1 in the axial direction of the regulated magnet 42a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric type having a pair of electrode tips, wherein one of the electrode tips is opened and closed with respect to the other under the rotation of a feed screw mechanism connected to a servomotor. Related to welding guns.

[0002]

2. Description of the Related Art For example, a welding gun for spot welding is used for lap welding of sheet materials. Normal,
In this type of welding gun, a pneumatic or electric servo gun is employed from the viewpoint that control of the opening of the pair of electrode tips is simplified.

In general, an electric welding gun, which is an electric servo gun, includes a servo motor, a pair of electrode tips,
A feed screw mechanism connected to the servomotor to move one of the pair of electrode tips. In this electric welding gun, a member to be welded is sandwiched between a pair of electrode tips, and a current is applied between the electrode tips while pressurizing with a feed screw mechanism under the action of a servomotor. Is welding.
This makes it possible to easily cope with a change in the plate thickness of the member to be welded and a change in the number of superposed members to be welded.

In order to enhance the strength of the member to be welded, it is desired to increase the thickness of the member to be welded and to complicate the overlapping shape of the member to be welded. Furthermore, it is desired to suppress the influence of distortion after press molding. In order to meet this kind of demand, it is necessary to increase the torque of the electric welding gun.

[0005]

However, as described above, when an attempt is made to increase the torque of the electric welding gun, the servomotor becomes considerably large in the radial direction and becomes heavy. Thus, there is a problem that workability of the electric welding gun is reduced. Moreover,
It has been pointed out that the increase in the weight and the diameter of the rotor increases the centrifugal force during rotation of the rotor, lowers the opening and closing speed of the electrode tip, and lowers the work efficiency of the entire spot welding.

An object of the present invention is to solve such a problem, and an object of the present invention is to provide an electric welding gun capable of easily increasing the torque and improving the working efficiency.

[0007]

An electric welding gun according to the present invention comprises a pair of electrode tips, and one of the electrode tips is rotated by a feed screw mechanism connected to a servomotor. While the opening and closing operation is performed, the magnet fixed to the hollow rotor constituting the servomotor has the same diameter and thickness regardless of the magnitude of the output of the servomotor,
The axial dimension of the hollow rotor of the magnet,
It is set substantially in proportion to the output of the servomotor. And the coil which comprises a stator is arrange | positioned corresponding to the axial dimension of the magnet which opposes the said coil.

As described above, when increasing the torque of the servomotor, the radial dimension of the servomotor does not increase, and the centrifugal force at the time of rotation is reduced by the normal torque (which is used for general spot welding). (The torque of the servo motor). Accordingly, high-speed rotation is performed by increasing the output, and the opening / closing speed of the electrode tip can be improved, so that the cycle time can be effectively reduced.

The hollow rotor has a predetermined number of magnets arranged in parallel in the axial direction in accordance with the output of the servomotor. For this reason, when various servo motors having different outputs are used, it is not necessary to prepare magnets having different lengths for each servo motor, and the magnets can be shared, which is extremely economical. .

[0010]

FIG. 1 is a partially omitted side view showing a state in which an electric welding gun 10 according to a first embodiment of the present invention is attached to the tip of a robot arm 12. FIG. The electric welding gun 10 is configured as a C-type welding gun in which the movable electrode tip 30 linearly opens and closes with respect to the fixed electrode tip 32, as described later, but is not limited thereto. The movable electrode tip 30 may be configured as an X-type welding gun that swings with respect to the fixed electrode tip 32.

The electric welding gun 10 includes a gun supporting portion 14.
And a gun body 16. This gun support 14
Is attached to the tip of the robot arm 12 to support the gun body 16. The gun support part 14 is provided with a gun support bracket 18, and this gun support bracket 18
An upper plate 18a and a lower plate 18b extending in parallel with the upper plate 18a are provided. Upper plate 18a and lower plate 1
8b, a guide bar 20 is bridged.

The guide bar 20 includes the guide bar 20.
A plate body 22 that is slidable in the axial direction and is parallel to the upper surface plate 18a and the lower surface plate 18b is fitted. A housing-like support 24 is disposed on the upper side of the plate 22 on the side close to the robot arm 12, and the upper plate 18 a and the support 24
Between them, a first coil spring 26 wound around the guide bar 20 is interposed. Similarly, the lower plate 18
A second coil spring 28 wound around the guide bar 20 is interposed between b and the plate 22.

A casing 29 constituting the gun body 16 is fixedly held on the plate 22 on a side away from the robot arm 12. As shown in FIGS. 1 and 2, the gun body 16 includes a movable electrode tip 30 and a fixed electrode tip 32, which are a pair of electrode tips, and is rotated by a feed screw mechanism 36 connected to a servomotor 34. The movable electrode tip 30 is opened and closed linearly with respect to the fixed electrode tip 32.

The servo motor 34 is provided with a motor housing 38 fixed to the casing 29, a stator 40 fixed in the motor housing 38, and rotatably housed in the motor housing 38.
And a motor housing cover 50 provided on one end 48 side of the rotor 46.

As shown in FIG. 3, an annular magnet 42 is fixed to the outer periphery of the rotor 46. The magnet 42 has a diameter, for example, an inner diameter D, regardless of the output of the servomotor 34. And the thickness t are set to the same size, while the rotor 4 of the magnet 42 is
The dimension S in the axial direction (direction of arrow A) of No. 6 is set substantially in proportion to the output of the servomotor 34.

The output of the servo motor 34 is set, for example, to twice the output of a servo motor used for general spot welding (hereinafter referred to as a "specified servo motor"). S is a magnet of the specified servo motor (hereinafter referred to as a specified magnet 42).
a) is set to twice the dimension S1 in the axial direction. In the first embodiment, the above-described prescribed magnet 42a is used, and the two prescribed magnets 42a are arranged in parallel in the axial direction to constitute the magnet 42. The prescribed magnet 4
Instead of using 2a, a single magnet 42 set to the dimension S in the axial direction may be used.

The coil 40a constituting the stator 40 is
It is arranged annularly inside the motor housing 38,
The dimension in the direction of arrow A is set corresponding to the dimension S in the axial direction of the magnet 42 facing the coil 40a.

A cylindrical member 52 is coaxially screwed to an end of the motor housing 38, and a first member 52 is provided between the inner peripheral surface of the cylindrical member 52 and the outer peripheral surface of the end 48 of the rotor 46.
And second bearings 54 and 56 are interposed. The outer peripheral surface of the other end 58 of the rotor 46 and the motor housing 38
A third bearing 60 is interposed between the third bearing 60 and the inner peripheral surface of the third bearing 60.

The end portion 58 of the rotor 46 projects axially from the end surface of the third bearing 60 by a distance L,
The motor housing 38 has a ring-shaped end 62 facing the end 58. A seal member 66 is press-fitted into an opening 64 formed by the ring-shaped end 62, the third bearing 60, and the end 58.

As shown in FIGS. 2 and 4, the motor housing 38 has a substantially cylindrical shape and is made of, for example, an aluminum material. This motor housing 38
Inside, a cooling medium passage 70 for supplying a cooling medium (for example, cooling water) is formed. The passage 70 is constituted by a copper pipe 72, and the pipe 72 is
It is arranged spirally and is cast in the motor housing 38.

At the inlet 74 and outlet 76 of the conduit 72,
Prior to casting, copper cylindrical holder members 78 and 80 are fixed in advance by, for example, brazing. The holder members 78 and 80 have a predetermined thickness, and are cast into the motor housing 38 so as to cover the inlet 74 and the outlet 76 of the conduit 72.

As shown in FIG. 2, the end 48 of the rotor 46
An opening 82 as a concave portion is formed at the upper end of the opening 48. A spline hole 84 formed through the center of the end 48 communicates with the inner end of the opening 82. End 4
A thin plate 86 is fixed to the upper surface of 8, and closes the opening 82. A tightening nut 88 is screwed into the upper outer periphery of the end portion 48 of the rotor 46, and the first bearing 54 is preloaded by the tightening nut 88 to prevent the rotor 46 from rattling in the axial direction. .

The feed screw mechanism 36 is connected to the end 4 of the rotor 46.
8 has a feed screw 90, a nut member 92 screwed to the feed screw 90, and a hollow rod 94 fixed to the nut member 92. The feed screw 90 has a spline shaft portion 96 fitted into a spline hole 84 provided in the end portion 48 of the rotor 46, and a spline shaft portion 9.
6 and a screw portion 98 provided at an end portion thereof. By screwing the nut 100 into the screw portion 98,
The feed screw 90 is fixed to the rotor 46.

The end surface 102 of the nut member 92 faces the end portion 48 of the rotor 46, and a buffer member 104 is fixed to the end surface 102. The buffer member 104, the nut member 92, and the hollow rod 94 are integrally fixed via a first screw 110, and the nut member 92 and the hollow rod 94 are integrally connected via a second screw 112. Fixed to

The hollow rod 94 is configured to be long in the direction of arrow A, is disposed in the hollow portion 44 of the rotor 46, and has a spline 114 formed on the outer periphery thereof. The spline 114 is screwed into a spline hole 116 provided in the casing 29, and has a function of preventing the hollow rod 94 and the nut member 92 from rotating. The movable electrode tip 30 is provided at the tip of the hollow rod 94.
Are detachably mounted via the holder 118.

As shown in FIG. 1, the casing 29 includes
A pair of C-shaped yokes 120a and 120b extend downward and are fixed, and the fixed electrode chip 32 is detachably held by a holding member 122 attached between the yokes 120a and 120b. I have.

A head cover 130 is mounted above the motor housing cover 50 of the servomotor 34 (see FIG. 2). In this head cover 130,
Encoder 13 for detecting rotation angle of rotor 46
2 are arranged. The encoder 132 includes an encoder body 134 and an input shaft 136 projecting downward from the encoder body 134.
34 is held by a cylindrical stay 138 fixed to the motor housing cover 50. Input shaft 13
6 is connected to the thin plate 86 through a hole 140 provided substantially at the center of the motor housing cover 50.

As shown in FIG. 1, on the side surface of the head cover 130, a substantially L-shape for connecting power wirings 144 and 146 from a servo gun control unit 142 serving as a driving source for operating the servo motor 34 and the encoder 132 is provided. The first and second power supply connection ports 148 and 150 are provided.

The electric welding gun 10 constructed as described above
Will be described below.

When electric power is supplied from the servo gun control unit 142 to the servo motor 34, the coil 40a is energized to generate a magnetic field under the action of the stator 40 and the annular magnet 42 facing the stator 40. For this reason,
The rotor 46 constituting the servomotor 34 rotates.

The feed screw 90 of the feed screw mechanism 36 is rotated by the rotation of the rotor 46, and a nut member 92 screwed to the feed screw 90 is connected to a hollow rod 94.
And one end of the feed screw 90 in the axial direction (arrow A1).
Direction). This is because the spline 114 formed on the outer peripheral surface of the hollow rod 94 is screwed into the spline hole 116 of the casing 29,
This is because the rotation of the nut member 92 is restricted.

Accordingly, the movable electrode tip 30 held by the holder 118 fixed to the distal end of the hollow rod 94
Moves in the direction of arrow A1, and the workpiece W is pressed and held by the fixed electrode tip 32 and the movable electrode tip 30. In this state, a large current is supplied between the movable electrode tip 30 and the fixed electrode tip 32, and the work W is spot-welded.

At this time, a passage 70 is provided in the motor housing 38 of the servo motor 34 by casting a copper pipe 72, and a cooling medium, for example, cooling water is supplied to the passage 70. I have. Therefore, the servo motor 3
4 is forcibly cooled by the cooling water spirally flowing through the motor housing 38 via the pipe 72, so that the servo motor 34 can be used even when increasing the torque of the electric welding gun 10. The calorific value does not increase.

In this case, in the first embodiment, the rotor 4
6, an annular magnet 42 is fixed, and the magnet 42 has the same inner diameter D and the same thickness t regardless of the magnitude of the output of the servomotor 34, while the magnet 42 has the same size. The dimension S of the rotor 46 in the axial direction (the direction of arrow A) is set substantially in proportion to the output of the servomotor 34.

Specifically, in the servo motor 34 set to twice the output of the specified servo motor, the magnet 42
Is set to twice the axial dimension S1 of the prescribed magnet 42a. Thus, when increasing the torque of the servo motor 34, the servo motor 3
Since the radial dimension of 4 does not increase, the centrifugal force when the servo motor 34 rotates can be suppressed to be equal to the centrifugal force of the specified servo motor.

Therefore, in the servo motor 34, high-speed rotation is performed by increasing the output, and the opening / closing speed of the movable electrode tip 30 with respect to the fixed electrode tip 32 can be improved. Thereby, the cycle time of the spot welding by the electric welding gun 10 can be effectively shortened, and the effect that the productivity can be improved with a simple configuration is obtained.

Further, in the first embodiment, the magnet 42 is formed by arranging two prescribed magnets 42a in the axial direction. Therefore, when various servomotors 34 having different outputs are used, it is not necessary to prepare magnets 42 having different lengths (dimensions in the axial direction) for each servomotor 34, and the specified magnet 42a can be shared. This has the advantage of being very economical.

FIG. 5 is an explanatory sectional view of an electric welding gun 160 according to a second embodiment of the present invention. The same components as those of the electric welding gun 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The servo motor 162 constituting the electric welding gun 160 includes a motor housing 164 fixed to the plate 22, a stator 40 fixed in the motor housing 164, and a rotatable rotation in the motor housing 164. And a rotor 46 housed therein and having a hollow portion 44 formed in the center. In the second embodiment, the pipe 72 is not cast in the motor housing 164.

A gun barrel 166 is fixed to the lower plate 18b, and a spline 114 of the hollow rod 94 is screwed into a spline hole 116 formed in the gun barrel 166.

In the second embodiment configured as described above, the axial dimension S of the magnet 42 is set to twice the axial dimension S1 of the prescribed magnet 42a.
When increasing the torque of the servomotor 162, the radial dimension of the servomotor 162 does not increase. Thereby, the cycle time of spot welding by the electric welding gun 160 can be effectively shortened, and it is possible to improve productivity with a simple configuration, and the same effects as those of the first embodiment can be obtained. can get.

In the first and second embodiments, the axial dimension S of the magnet 42 is
Although the case where the dimension S is set to twice the axial dimension S1 has been described, the present invention is not limited to this.
The dimension S can be set to be three times the dimension S1, and the three magnets 42a can be arranged in parallel to form the magnet 42.

[0043]

In the electric welding gun according to the present invention, the magnet fixed to the hollow rotor constituting the servo motor has the same diameter and thickness regardless of the output of the servo motor. On the other hand, the dimension of the magnet in the axial direction of the hollow rotor is set substantially in proportion to the output of the servomotor. Therefore, when increasing the torque of the servomotor, the radial dimension of the servomotor does not increase, and the centrifugal force during rotation can be effectively suppressed. Accordingly, high-speed rotation is performed by increasing the output, and the opening / closing speed of the electrode tip can be improved, so that the cycle time can be effectively reduced.

[Brief description of the drawings]

FIG. 1 is a partially omitted side view showing a state in which an electric welding gun according to a first embodiment of the present invention is attached to a distal end of a robot arm.

FIG. 2 is an explanatory sectional view of the electric welding gun.

FIG. 3 is an enlarged view showing the inside of a servomotor constituting the electric welding gun.

FIG. 4 is a perspective view showing the inside of a motor housing constituting the electric welding gun.

FIG. 5 is an explanatory sectional view of an electric welding gun according to a second embodiment of the present invention.

[Explanation of symbols]

10, 160 ... electric welding gun 12 ... robot arm 14 ... gun support 16 ... gun body 29 ... casing 30 ... movable electrode tip 32 ... fixed electrode tip 34, 162 ... servo motor 36 ... feed screw mechanism 38, 164 ... Motor housing 40 ... Stator 40a ... Coil 42 ... Magnet 42a ... Prescribed magnet 44 ... Hollow part 46 ... Rotor 48 ... End part 72 ... Pipe line 78, 80 ... Holder member 84, 116 ... Spline hole 90 ... Feed screw 92 ... Nut member 94: hollow rod 96: spline shaft 114: spline

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akiyoshi Shimizu 1-10-1 Shinsayama, Sayama City, Saitama Prefecture Honda Engineering Co., Ltd. (72) Inventor Takuro Kugimiya 1-10-1 Shinsayama, Sayama City, Saitama Prefecture Hondae Engineering Co., Ltd. (72) Inventor Osamu Kurihara 1-10-1 Shinsayama, Sayama City, Saitama Prefecture Honda Engineering Co., Ltd. F-term (reference) 4E065 AA05 BA06

Claims (2)

[Claims] 1. An electric 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 includes: a motor housing mounted on a welding gun main body; a stator fixed in the motor housing; and a hollow rotor rotatably housed in the motor housing. The magnet fixed to the rotor has the same radial dimension and thickness regardless of the magnitude of the output of the servomotor, while the axial dimension of the hollow rotor of the magnet is
The electric welding is set substantially in proportion to the output of the servomotor, and the coil constituting the stator is arranged corresponding to the axial dimension of the magnet facing the coil. gun. 2. The electric welding gun according to claim 1, wherein
The electric welding gun according to claim 1, wherein the hollow rotor has a predetermined number of the magnets arranged in parallel in the axial direction in accordance with an output of the servomotor.