JPH0547313B2 - - Google Patents

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, and are especially used for work in environments that are dangerous or harsh for humans, and that require high precision, high speed, etc. that are impossible for humans. It shows its power in such tasks.

One such industrial robot is a welding robot, an example of which 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 a vertical arm 4 is attached to the lower surface of the tip of the horizontal arm 3.
is provided rotatably around an axis in the Z-axis direction, and an attachment 5 having a gripping function is provided at the lower end of the vertical arm 4, and is rotatable around a pin 6 and attached to the lower end of the vertical arm 4.
It is mounted so that it can rotate around an axis perpendicular to .

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 10 is fed out by the feeder 11, and the wire 9 penetrates through the torch cable 8 and the inside of the torch 7 and protrudes from the tip of the torch 7 by a required amount.

As a result, in addition to lifting and rotating the main body 2, moving the horizontal arm 3, and rotating the vertical arm 4, the attachment 5 can rotate around the pin 6 and rotate around the axis perpendicular to the pin 6. Then,
While maintaining the appropriate torch posture relative to the workpiece,
Welding is performed by moving the base 1 along the welding line.

[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.
There will be a distance l between the torch 7 and the rotation center that changes the inclination angle of the torch 7, and when welding in a narrow area, if you try to maintain the appropriate posture of the torch 7, the lower end of the vertical arm 4 will Part is work 12
This has caused problems in that the welding cannot be performed in an appropriate position, resulting in a decrease in the quality of welding and increasing restrictions on the locations that can be welded.

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 rotatable mechanism between a pair of casing tip portions of an arm extending in parallel with a required spacing, which is rotatable about an axis orthogonal to the longitudinal direction of the casing. A torch arranged parallel to the longitudinal direction of the casing is supported on the rotating block so that the axis of the torch intersects with the rotational axis of the rotating block, and the rotating A rotation transmitting member rotatable about the torch axis is arranged concentrically with the torch on the distal end side of the block, and a torsion member fitted on the torch is placed in a recess formed on the distal end side of the rotation transmitting member. A flange portion of the sleeve is provided to be freely displaceable in the direction of the torch axis, and a protrusion is provided that urges the flange portion of the twisted sleeve toward the tip side of the torch, presses it against the support portion of the rotation transmission member, and acts in the direction of the torch axis. An elastic member is provided to absorb the lifting force, and the rotation transmission member is further provided with a proximity sensor capable of detecting displacement of the torch toward the proximal end in the axial direction by detecting a groove formed on the outer peripheral surface of the torch. It has a set configuration.

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

Additionally, when an arc is generated by pressing the wire protruding from the tip of the torch against the workpiece at the start of welding, the impact force applied in the direction of the torch axis is absorbed by the elastic member, preventing unnecessary force from acting on the torch. Further, when the wire remains pressed against the workpiece, the groove of the torch moves toward the proximal end in the axial direction of the torch, and the movement of the groove is detected by the proximity sensor, The torch can be moved in a direction away from the workpiece based on the detection signal from the workpiece.

[Example] Hereinafter, an example of the present invention will be described 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, a welding torch 7 is attached to the lower end of the vertical arm 4, that is, at the wrist. The torch is attached so that it can be rotated about an axis perpendicular to the torch and twisted about the torch axis.

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
3 (FIG. 1), and left and right casings 14 fixed to the lower surface of the rotary disk 13 and extending downward parallel to each other.
a, 14b, the casing 14a,
The torch 7 is disposed between the tips of the casings 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 arranged at a required position within the casing 14a, and an output shaft of the motor 15a has a
A drive shaft 16 arranged on an extension of the shaft center of the motor 15a.
a is connected via the reducer 17a, and the drive shaft 16
a is supported by a bearing 18a, and the drive shaft 16
A bevel gear 19a is fitted and fixed to the lower end of a. A bevel gear 20a whose rotation axis extends horizontally and is orthogonal to the 7th axis of the torch is meshed with the bevel gear 19a and supported by a bearing 21a, and one end of the driven shaft 22a of the bevel gear 20a is concentrically connected to the bevel gear 19a. Fit and secure. A box-shaped rotating block 23 through which the torch 7 passes vertically 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. A bearing 2 whose inner ring is fitted and fixed to the casing 14a at its core
It is supported by the outer ring of 4a, and the right side frame part 23
b supports the outer ring of a bearing 24b which is located symmetrically with the bearing 24a and whose inner ring is fitted and fixed to the casing 14b. A ring-shaped spherical seat 25 with a spherical inner surface is fitted into a through hole 23e formed in the upper frame portion 23c of the rotating block 23, and an insulating material is placed on the outer peripheral portion of the torch 7 corresponding to the spherical seat 25. A spherical member 27 is fitted and fixed through the sleeve 26, and the spherical member 27 is slidably fitted to the spherical seat 25. In addition, the lower frame portion 23d of the rotating frame 23
A through hole 23f concentric with the torch 7 is bored in the through hole 23f, 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. The bevel gear 19
b, a bearing 21b concentric with the bevel gear 20a;
A bevel gear 20b supported by the driven shaft 22b is meshed with the bevel gear 20b, one end of a driven shaft 22b provided on the same axis as the driven shaft 22a is fitted and fixed, and the other end of the driven shaft 22b is fitted with a bevel gear 20b. The gear 28 is fitted and fixed, and the bevel gear 28 is supported by a bearing 29.
The bevel gear 30 loosely fitted on the torch 7 is meshed with the bevel gear 28, and the rotating block 23
Supported by the bearing 31 of the lower frame portion 23d,
A rotation transmission member 32 loosely fitted to the torch 7 is integrally attached to the lower end of the bevel gear 30. The rotation transmitting section 32 has a structure in which a small-diameter cylindrical section 32a and a large-diameter cylindrical section 32b are stacked concentrically vertically. A recess 32d is provided, and a flange 33a of a torsion sleeve 33, which will be described later, is assembled in advance into the recess 32d, and an inclined surface 32e that slopes in a dome shape toward the center is formed at the inner edge of the opening of the recess 32d. A supporting portion 32f is provided. still,
Radial lines may be carved on the inclined surface 32e if necessary. A torsion sleeve 33 having a flange portion 33a that can engage with the inclined surface 32e of the support portion 32f is fitted and fixed at a predetermined position of the torch 7, and the torsion sleeve 33 is urged downward (toward the tip side of the torch 7). An elastic member 34 such as a compression spring is provided between the torsion sleeve 33 and the rotation transmission member 32 for pressing the flange portion 33a against the support portion 32f and absorbing the thrusting force acting in the axial direction of the torch 7. Incidentally, 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, and a proximity sensor 36 is installed in the hole 35.
The sensor portion of the proximity sensor 36 is inserted toward the torch 7 side, and a groove 37 for position detection is formed on the outer peripheral surface of the torch 7 facing the sensor portion. Incidentally, an insulating film is applied to the outer peripheral surface of the torch 7.

Since the configuration is as described above, the rotation motor 15a
When the drive shaft 16a is rotated via the reducer 17a, the rotation of the drive shaft 16a is transmitted to the driven shaft 22a via the bevel gears 19a and 20a,
The driven shaft 22a rotates the rotating block 23 about the axes of the driven shafts 22a, 22b. Along with this, the spherical seat 25 fitted with the spherical member 27
and the torsion sleeve 33 is connected to the driven shafts 22a, 22.
By rotating and moving around the axis of b,
The torch 7 rotates around the axes of the driven shafts 22a and 22b, and the inclination angle with respect to the workpiece can be freely adjusted. 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 15a 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, it rotates together with the rotation transmission member 32 due to its 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;
The impact force applied in the axial direction is absorbed by the elastic member 34, so that no unnecessary force is applied to the torch, gear mechanism, etc. Furthermore, if the wire 9 remains pressed against the workpiece, the groove 37 of the torch 7 moves upward, so the proximity sensor 36 connects the outer peripheral surface of the torch 7 and the through hole of the rotation transmission member 32. 32c is detected, and based on the change, the torch 7 is immediately moved in a direction away from the workpiece.

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, but it goes without saying that the torch 7 can be applied to the tip of the arm 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 range in which the welding robot can weld is expanded. When an arc is generated by pressing a protruding wire against a workpiece, the elastic member absorbs the impact force applied in the direction of the torch axis, making it possible to prevent unnecessary force from acting on the torch. , it is possible to reduce failures of the torch drive system, and furthermore, when the wire is still pressed against the workpiece, the torch is moved away from the workpiece based on the detection signal from the proximity sensor. Since it can be moved, an excellent effect can be achieved in that welding can be performed satisfactorily.

[Brief explanation of drawings]

FIG. 1 is an overall side view showing one embodiment of the present invention;
2 is a cross-sectional view taken from FIG. 1, FIG. 3 is an overall side view showing a conventional example, and FIG. 4 is an explanatory diagram of a welding state in the conventional example. 1 is a base, 2 is a main body, 3 is a horizontal arm, 4 is a vertical arm, and 7 is a torch.

Claims (1)

[Claims] 1. A rotating block rotatable about an axis perpendicular to the longitudinal direction of the casing is disposed between a pair of casing tips of an arm extending in parallel with a required interval, and the rotating block is provided with the A torch arranged parallel to the longitudinal direction of the casing is supported so that the axis of the torch intersects with the rotational axis of the rotating block, and a torch is placed on the tip side of the rotating block with the torch axis centered on the axis of the rotating block. A rotatable rotation transmission member is disposed concentrically with the torch, and a flange portion of the torsion sleeve fitted to the torch is placed in a recess formed on the distal end side of the rotation transmission member.
Provided to be freely displaceable in the direction of the torch axis, and to urge the flange portion of the twisted sleeve toward the torch tip side to press against the support portion of the rotation transmission member and to absorb thrust force acting in the direction of the torch axis. an elastic member is provided, and the rotation transmission member further includes:
A wrist mechanism for an arc welding robot, characterized in that it is provided with a proximity sensor capable of detecting displacement of the torch toward the proximal end in the axial direction by detecting a groove formed on the outer peripheral surface of the torch.