JPH01157775A - Wrist mechanism for arc welding robot - Google Patents

Abstract

PURPOSE:To perform robot welding of a narrow part by rotating a torch round the shaft centers of driven shafts to cross orthogonally to the shaft center of the torch and controlling synchronously a motor for torsional rotation to hold a position of the torch constant. CONSTITUTION:A turning motor 15a is driven and the torch 7 is rotated round the shaft centers of the driven shafts 22a and 22b to cross orthogonally to the shaft center of the torch 7 via a driving shaft 16a and a turning block 23. At this time, the position of the torch 7 in the torsional rotational direction is not changed by the synchronous control of the motor 15b for torsional rotation. By this method, welding of the narrow part which has been impossible to realize so far can be performed and the applicable range of the welding robot can be extended.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wrist mechanism for an arc welding robot.

[Conventional technology] In recent years, industrial robots have become widespread, especially for tasks that are dangerous or harsh to humans, or that require high precision and speed that are impossible for humans to perform. It shows its power in its work.

One of these industrial robots is a welding robot.
An example of this is shown in FIG.

A main body 2 that can be moved up and down in the Z-axis direction (vertical direction in the figure) and rotatable around the Z-axis is erected on a movable base 1 so as to be movable in the X-axis direction (direction perpendicular to the figure). A horizontal arm 3 is attached to the upper end of the main body 2 so as to be movable in the Y-axis direction (horizontal direction in the figure), and on the lower surface of the tip of the horizontal arm 3,
A vertical arm 4 is provided rotatably around an axis in the Z-axis direction,
An attachment 5 having a gripping function is attached to the lower end of the vertical arm 4 so as to be rotatable about a pin 6 and about an axis perpendicular to the pin 6.

The attachment 5 holds a torch 7 whose tip is bent at a predetermined angle, while a wire reel 10 on which a welding wire 9 is wound is mounted on the back of the main body 2, and a feeder for feeding out the wire 9. 11 is installed, the wire outlet of the feeder 11 and the base end of the torch 7 are connected by a torch cable 8, the wire 9 wound around the wire reel IO is fed out by the feeder 11, and the wire 9 is connected to the torch cable. 8 and the inside of the torch 7 to pass through the torch 7.
It is designed so that it protrudes the required amount from the tip.
' As a result, in addition to the vertical movement and rotation of the main body 2, the movement of the horizontal arm 3, and the rotation of the vertical arm 4, the rotation of the attachment 5 around the pin 6 and the rotation movement around the axis perpendicular to the pin B are performed. Accordingly, welding is performed by moving the base 1 along the welding line while appropriately maintaining the torch posture relative to the workpiece.

[Problems to be Solved by the Invention] However, when the torch 7 is held by the attachment 5 attached to the lower end of the vertical arm 4 as described above, as shown in FIG.
The distance between the rotation center and the center of rotation that changes the inclination angle of! When welding in a narrow area, the lower end of the vertical arm 4 will interfere with the workpiece 12 if the torch 7 is held in an appropriate position, making it impossible to weld in the correct position. As a result, the quality of welding deteriorates, and there are more restrictions on the locations where welding can be performed.

In view of these circumstances, the present invention aims to provide a wrist mechanism for an arc welding robot that can expand the welding range.

[Means for Solving the Problems] The present invention provides a torch disposed parallel to the longitudinal direction of the casing between a pair of casing tips of arms extending parallel to each other with a required interval. It has a configuration in which it is attached so that it can rotate about an axis that passes through the torch axis and is orthogonal to the torch axis, and can also be twisted about the torch axis.

[Function] Therefore, since there is no distance between the torch and the center of rotation for changing the inclination angle of the torch, the tip of the arm does not interfere with the workpiece even when welding in a narrow area. The torch can be held in an appropriate position.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

Note that in FIGS. 1 and 2, the same reference numerals as in FIG. 3 indicate the same parts.

As shown in FIG. 1, at the lower end of the vertical arm 4, that is, at the wrist,
The welding torch 7 is rotatable in a vertical plane including the vertical arm 4 about an axis that passes through the torch axis and is orthogonal to the torch axis. Install it so that it can be twisted around the center.

Next, a mechanism for rotating the torch 7 with respect to the vertical arm 4 will be specifically explained.

As shown in FIG. 2, the vertical arm 4 is
), and left and right casings 14a fixed to the lower surface of the rotary disk 13 and extending downward parallel to each other.

14b, the torch 7 is disposed between the tips of the casings 14a and 14b, and a rotating mechanism for the torch 7 is provided on one casing 14a side, and a rotating mechanism for the torch 7 is provided on the other casing 14b side.

A rotation motor 15a is provided at a required position within the casing 14a.
is placed on the output shaft of the motor 15a.
A drive shaft lea disposed on the extension of the shaft center is connected via a speed reducer 17a, the drive shaft lea is supported by a bearing 18a, and a bevel gear 19a is fitted and fixed to the lower end of the drive shaft lea. A bevel gear 20a whose rotation axis extends horizontally and is orthogonal to the 7-axis axis of the torch is meshed with the bevel gear 19a and is supported by a bearing 21a.
One end of the driven shaft 22a is fitted and fixed concentrically.

A box-shaped rotating block 23 through which the torch 7 vertically passes is fitted and fixed to the other end of the driven shaft 22a, and the left side frame 23a of the rotating block 23 is aligned on the same axis as the bearing 21a. The inner ring of the bearing 24a is fitted and fixed to the casing 14a at its center, and is supported by the outer ring of the bearing 24a.
b is located symmetrically with the bearing 24a and the casing 14b
The outer ring of the bearing 24b whose inner ring is fitted and fixed is supported by the outer ring of the bearing 24b. A ring-shaped spherical seat 2 with a spherical inner surface is installed in a through hole 23e formed in the upper frame portion 23c of the rotation block 23.
5, and a spherical material 27 is fitted and fixed to the outer circumferential portion of the torch 7 corresponding to the spherical seat 25 through an insulating sleeve 26, so that the spherical material 27 is slidable relative to the spherical seat 25. Fit them together. A through hole 23f concentric with the torch 7 is formed in the lower frame portion 23d of the rotating frame 23, and a bearing 31 is fitted into the through hole 23f'.

On the other hand, as a rotation mechanism of the torch 7, a drive shaft 16b supported by a bearing 18b is connected to a torsion motor 15b arranged in a casing 14b so as to be symmetrical with the rotation motor 15a, via a speed reducer 17b. The bevel gear 19b is fitted and fixed to the lower end of the drive shaft 16b. A bevel gear 20b supported on a bearing 21b concentrically with the bevel gear 20a is engaged with the bevel gear 19b, and one end of a driven shaft 22b is provided on the same axis as the driven shaft 22a. the driven shaft 22b.
A bevel gear 28 is fitted and fixed to the other end, and the bevel gear 28
is supported by a bearing 29. A bevel gear 30 loosely fitted onto the torch 7 is meshed with the bevel gear 28 and supported by the bearing 31 of the lower frame portion 23d of the rotating block 23. The loosely fitted rotation transmission member 32 is attached integrally. The rotation transmission member 32 has a structure in which a small-diameter cylindrical portion 32a and a large-diameter cylindrical portion 32b are concentrically stacked vertically, and the bottom of the cylindrical portion 32b has a hole larger than the 1-thia through hole 32c. Diameter concave portion 32d
A flange portion 33a of a torsion sleeve 33, which will be described later, is assembled in advance into the recess 32d.
A support portion 32f is provided at the inner edge of the opening, and is provided with an inclined surface 32e that slopes in a dome shape toward the center. Incidentally, radial lines may be carved on the inclined surface 32e if necessary. The support portion 32 is placed at the required position of the torch 7.
A torsion sleeve 33 having a flange portion 33a that can be engaged with the inclined surface 32e of f is fitted and fixed, and the torsion sleeve 33
is forced downward (toward the tip side of the torch 7) and the flange portion 33a
The elastic member 3, such as a compression spring, is used to press the
4 is provided between the torsion sleeve 33 and the rotation transmission member 32. In addition, when radial grooves are carved on the inclined surface 32e, grooves that mesh with the grooves may be carved on the engagement surface of the flange portion 33a.

Further, the cylindrical portion 32b of the rotation transmission member 32 is provided with a hole 35 that opens on the inner surface of the through hole 32c and extends in the radial direction,
The proximity sensor 3B is inserted into the hole 35, with the sensor part of the proximity sensor 36 facing the Torchia side, and a groove 37 for position detection is formed on the outer peripheral surface of the torch 7 facing the sensor part.

Incidentally, the outer peripheral surface of the torch 7 is coated with an insulating film.

Since the configuration is as described above, when the rotation motor 15a is driven and the drive shaft 18a is rotated via the reducer 17a,
The rotation of the drive shaft lea is a bevel gear 19a.

20a to the driven shaft 22a, and the driven shaft 22a
The rotation block 23 is rotated about the axes of the driven shafts 22a and 22b. Along with this, the spherical seat 25 and the torsion sleeve 33 fitted with the spherical member 27 rotate around the axes of the driven shafts 22a, 22b, so that the torch 7 moves around the axes of the driven shafts 22a, 22b. Rotates around the center and can freely adjust the inclination angle with respect to the workpiece. At this time, the posture of the torch 7 in the twisting direction is kept unchanged by synchronous control of the twisting motor 15b, which will be described later.

On the other hand, when the torch 7 is twisted, the rotation motor L5a is restrained, and when the rotation motor 15b drives the drive shaft 16b via the reducer 17b, the bevel gear 20b meshing with the bevel gear 19b rotates, causing the driven shaft to rotate. 22b is rotated, the bevel gear 28 rotates together with the driven shaft 22b, and the bevel gear 30 that meshes with the bevel gear 28 rotates together with the rotation transmission member 32. At this time, the torsion sleeve 33
4 against the inclined surface 32e of the support portion 32f, the rotation transmission member 32 rotates together with the rotation transmission member 32 due to the frictional force. This allows the torch 7 to twist around its own axis and control the posture of the tip of the torch which bends.

Furthermore, at the start of welding, an arc is generated by pressing the wire 9 protruding from the tip of the torch 7 against the workpiece, but the impact force applied in the axial direction of the torch 7 at this time is absorbed by the elastic member 34. This prevents unnecessary force from acting on the torch, gear mechanism, etc. Furthermore, if the wire 9 remains pressed against the workpiece, the groove 37 of the torch will move upwards, so the proximity sensor 36 will move between the outer peripheral surface of the torch 7 and the through hole aZC of the rotation transmitting member 32. The torch 7 is immediately moved in a direction away from the workpiece based on this gap change.

In this way, since the torch 7 itself is rotatably and twistably attached to the lower end of the vertical arm 4, the workpieces come in close contact with each other, and even when welding in an extremely narrow area, there is no interference between the lower end of the vertical arm 4 and the workpiece. It becomes possible to maintain the posture of the torch 7 appropriately while avoiding this.

In the above embodiment, the torch 7 is attached to the lower end of the vertical arm 4.
Although an example is shown in which the present invention is attached, it goes without saying that it can be applied to the arm tip of various types of welding robots.

[Effects of the Invention] As described above, according to the present invention, it is possible to weld in narrow areas, which was previously impossible, and the welding robot has an excellent effect of expanding the range in which welding can be performed.

[Brief Description of the Drawings] Fig. 1 is an overall side view showing one embodiment of the present invention, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 is an overall side view showing a conventional example. FIG. 4 is an explanatory diagram of a welding state in a conventional example. 1 is the base, 2 is the main body, 8 is the horizontal arm, 4 is the vertical arm, and 7 is the torch.

Claims (1)

[Claims] 1) A torch is placed parallel to the longitudinal direction of the casing between the casing tips of a pair of arms extending in parallel with a required interval, and the torch passes through the torch axis and is orthogonal to the torch axis. A wrist mechanism for an arc welding robot, characterized in that the wrist mechanism is attached so as to be able to rotate around a torch axis and twist around a torch axis.