JPH0377781A - Robot for welding - Google Patents

Abstract

PURPOSE:To enable mutual positioning with energizing means with high accuracy by setting a detector, which detects position of a piece in the axial direction and outputs abnormality signal when a first shifting member displaces by the prescribed quantity or more to a second shifting member. CONSTITUTION:Even in the case a welding torch 24, etc., is displaced at some quantity with external force, as a consumable electrode wire is guided with a flexible guide, the consumable electrode wire is not abutted on the other member. Therefore, by removing the external force acted to the welding torch 24, etc., the welding torch 24, etc., is automatically returned back to the initial condition. In the case of detecting abnormal condition of the welding torch 24, the welding work can be interrupted with the abnormality signal or the abnormality alarm can be sounded. By setting the detector 25, breakage caused by abutting on the member does not occur. Further, as a movable part and the piece in the first shifting member are inserted in a cylinder of the second shifting member, dust, etc., is not mingled.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a welding robot that appropriately controls the position of a moving member that supports a welding torch.

<Prior art> In general, welding robots operate by operating a microcomputer based on numerical data or data input through teaching operations, or operate the robot by using a fixed electrical sequence control device. There is. By the way, when an obstacle is mistakenly placed within the operating range of the robot, for example, the welding torch and the obstacle come into contact, causing damage to the welding torch and the movable member that supports the welding torch. For this reason, there has been a demand for robots equipped with safety devices to prevent damage to various parts. Moreover, for example, the external force that acts on a welding torch is rarely limited to one direction, so in order to prevent damage to the welding torch even when an external force acts on the welding torch in an unspecified direction, it is necessary to It is necessary to release it in the direction of action. As a robot of this type, a robot equipped with a safety device having the structure shown in FIGS. 1 and 2 has been proposed. That is, a spherical bearing 53 consisting of a spherical concave body 51 and a spherical convex body 52 is provided at the tip opening of the movable member 11' whose position is appropriately controlled, and the spherical bearing 53 is inserted through the bored hole 54 of the spherical convex body 52. Welding torch 24'
, and the welding torch 24' is held at Z2 by the spring 55.
The welding torch was configured to be tiltable and movable in the z1 direction by biasing the welding torch in the z1 direction. Further, a fixed electrode 57 having an arcuate shape is attached to the rear end opening of the movable member 11' via an insulating material 56, and a first movable electrode radially shaped is attached to the tail end of the welding torch where the fixed electrode 57 is located. 58, 58... and a second movable electrode 59 extending in the radial direction are attached, and the contact state of the welding torch is determined by the movable electrode 58, 59, the fixed electrode 57, and the detector 60, 60 connected to these. It had been detected.

That is, for example, when a force in the X direction or Y direction is applied to the tip of the welding torch, the welding torch rotates about the spherical bearing, and the first movable electrode and the fixed electrode come into contact with each other.

Furthermore, when a force in the 21 directions is applied to the tip of the welding torch, the welding torch that passes through the hole in the spherical convex body moves in the 21 direction against the spring, and the second movable electrode and the fixed electrode are moved. come into contact with.

<Problem to be solved by the invention> By the way, the welding torch is displaced in the direction of action of external force,
Since the contact state of the welding torch is detected by the contact between the movable electrode and the fixed electrode, the amount of displacement of the welding torch with respect to the moving member is limited to an extremely small value. That is, when the amount of displacement of the welding torch becomes large, the movable electrode is pressed against the fixed member more than necessary, or the tail end of the welding torch comes into contact with the moving member, and the movable electrode and the welding torch are damaged. In addition, in order to tilt the spherical convex body smoothly in the spherical bearing part, the spherical convex body and the spherical concave body must be machined with high precision, and the spherical convex body must be held by the spherical concave body. In order to hold the spherical concave body, it is necessary to divide the spherical concave body into at least two parts in the radial direction or the pongee direction, but the work of forming the inner surface of the divided spherical concave body into a smooth spherical shape was troublesome. . Furthermore, when external forces in 21 directions are applied to the tip of the welding torch, if the hole in the spherical convex body is made larger in order to allow the welding torch to move smoothly, the positioning of the welding torch will become inaccurate. There was a drawback.

An object of the present invention is to provide a welding robot that eliminates the above-mentioned conventional drawbacks.

Means for Solving the Problems In order to achieve the above object, the configuration of the present invention includes a first moving member that supports a welding torch and a second moving member that supports the first moving member. In a welding robot that appropriately controls the position of a movable member, the second movable member is formed into a cylinder with a bottom, and a hole is bored through the bottomed part in the axial direction of the cylinder. A through hole is bored approximately in the axial center of the first movable member, and the free end of the first movable member faces the bottomed portion and the cylindrical portion through at least the through hole of the second movable member. A bulge is formed at the free end of the first movable member so that the first movable member is movable in the axial direction of the second movable member and in a direction tilted relative to the axis. A cylindrical piece that is substantially coaxial with the cylinder of the second moving member and movable in the axial direction is disposed in contact with the end, and the bulge of the first moving member is connected to the bottomed part of the second moving member. A first biasing means for biasing the cylindrical piece to come into contact with the shaped portion;
The second member is biased to abut against the free end of the moving member.
A flexible guide is provided that connects the welding torch with a through hole drilled in a substantially thin core portion at the end of the second moving member, and a shielding gas is applied to the second moving member. A connection port is provided to introduce the shielding gas into the welding torch through the external space of the flexible guide, and the first moving member is directed against the second moving member against the urging force of the urging means. The present invention is characterized in that a detector is provided that detects the position of the piece in the axial direction and outputs an abnormal signal when the piece is displaced by a predetermined amount or more.

<Embodiments> The present invention will be described in detail below with reference to illustrated embodiments. Now, to describe the multi-joint arm type welding robot, in Figs. 3 to 5, 1 is an underframe supported horizontally with respect to a fixed member 2, and 3 and 4 are attached to the underframe 1. 5 is a rear arm rotatably supported by the link lever 4, and 6 is an upper arm rotatably supported by the lower arm 3 and rear arm 5, respectively. , the upper arm 6, the lower arm 3, the link lever 4, and the rear arm 5 form a parallel link mechanism. A moving member 11 is supported at the end of the upper arm 6 directly or indirectly via a suitable drive mechanism.

7 and 8 are first and second rotary drive machines supported by the underframe 1, and the lower arm 3 is connected to the first rotary drive machine 7 via a reduction gear.
The upper arm 6 is rotated vertically by the lower arm 3 and the upper arm 6 through the link lever 4 and the rear arm 5, which are rotated by the second rotary drive 8B via the reducer. rotated in the direction. Further, the underframe 1 is rotated in the horizontal direction by a third rotary drive machine 9 via a reduction gear.

In the illustrated case, the moving member 11 is, for example, a horizontal rotation mechanism 10.
The movable member 11 supports an appropriate consumable electrode type welding torch 24 on the upper arm 6 via the movable member 11 . More specifically, in FIGS. 4 and 5, 1
2 is a first moving member that supports a welding torch 24 at one end; in the illustrated case, the welding torch 24 is attached to the first moving member 12;
It is screwed on. A through hole 121 is formed in the substantially axial center of the first moving member 12, and a disk-shaped bulge 122 that protrudes in the radial direction is formed at the end in the z1 direction. The outer surface of the bulging portion 122 is formed into a spherical convex shape 123. Reference numeral 13 designates a second moving member for supporting the first moving member 12, which includes a bottomed portion 131 and a cylindrical portion 132.
is formed. In addition, the bottomed portion 131 has a through hole 1.
33 is bored, and the first
The bulging portion 122 of the moving member 12 is accommodated in the cylindrical portion 132 of the second moving member 13 , and the flange surface 124 of the bulging portion 122 abuts the bottomed portion 131 of the second moving member 13 . Note that since the curvature of the spherical convex portion 123 of the bulging portion 122 is formed between the radius of the cylindrical portion 132 and the path, the first moving member 12 can freely tilt and tilt relative to the second moving member 13. Can slide and move. Reference numeral 14 denotes a spring holder that locks the compression spring 19, and the first moving member 12 is always urged in the Z2 direction by one compression spring disposed between the spring holder 14 and the first moving member 12. has been done.

15 is a lid body, and this lid body 15 and the spring presser 14 are connected to the second
It is integrally fastened to the moving member 13 of , and is supported by a support bracket 17 via a suitable electrically insulating member 16 and connected to the horizontal rotation mechanism 10 . 12 to 17 above
The movable member 11 is constituted by. Reference numeral 18 denotes a cylindrical piece disposed so as to be movable in the Z direction approximately on the axis of the spring presser 14, and in the illustrated case, it is formed in a cylindrical shape having a flange portion 181 in the Z1 direction. Reference numeral 20 denotes a compression spring disposed between the lid 15 and the piece 18, and the spring force causes the piece 18 to move.
is always urged in the z2 direction and is in contact with the first moving member 12. Reference numeral 21 designates a flexible guide disposed between the lid 15 and the welding torch 24, and is made of, for example, a spirally formed wire rod with a circular or non-circular cross section, or a resin tube. In the illustrated case, an end portion of a flexible conduit tube (not shown) for guiding the consumable electrode wire is screwed into a threaded portion 151 screwed onto the lid 15. Further, 22 is a connection port for supplying shielding gas for welding, and the space communicating with this connection port 22 is shielded by appropriate airtight members 231, 232, 233, and 234, and is connected to the end of the piece 18 in the 22 direction. The welding torch 24 passes through the external space of the flexible guide through the drilled hole 182.
is connected to. A detector 25 is arranged to detect, for example, the position of the flange portion 181 of the piece 18. 26 is a cover made of rubber or synthetic resin and has appropriate flexibility; 27 is a power line for welding, which is supported on, for example, the lid 15 via an appropriate insulating member, and then connected to a welding torch; There is.

In the above configuration, the welding torch 24 welds the object to be welded while appropriately controlling the position of the movable member 11. In this case, the first moving member 12 biased by one spring
The bulging portion 122 is the bottomed portion 131 of the second moving member 13.
Therefore, the shielding gas supplied from the connection port 22 passes through the lower part of the piece 18 and reaches the welding torch 24. Further, a consumable electrode wire (not shown) is guided by a flexible guide 21 and fed to a welding position, and an electric power 13
Welding is performed while power is supplied to the welding torch via 127.

A case will be described in which an external force is applied to the tip of the welding torch during operation of the welding robot, that is, during welding or non-welding. 6 to 8, FIG. 6 is a flow diagram when no external force is applied to the welding torch, and in this state, it is assumed that, for example, an external force in the X1 direction is applied to the tip of the welding torch.

Curved convex portion 123 of bulge portion 122 of first moving member 12
Since the curvature is formed between the radius of the cylindrical portion 132 of the second moving member 13 and the path, the first moving member 12 tends to tilt counterclockwise.

In this case, the first moving member 12 is biased in the Z2 direction by the spring 19, and the flange surface 124 of the bulging portion 122
is in contact with the bottomed portion 131 of the second moving member 13, so that the spherical center point of the bulging portion 122: Ol is a distance M in the Zt direction;
A position displaced by Δz1; tilts appropriately at 02. In this case, as shown in FIG. 7, the piece 18 is moved by a distance ΔZ2 in the Z1 direction. In addition, there are 2
When an external force is applied in one direction, the bulging portion 122 of the first moving member 12 is displaced along the cylindrical portion 132 in the Z1 direction by, for example, a distance ΔZ3, as shown in FIG.

In addition, since the bulging part of the first moving member 12 is formed in a spherical convex shape, the first moving member 12 is connected to the second moving member 1.
The piece 18 can be tilted in any direction with respect to 3, and the bulge 122 is formed in a disk shape, and the abutment surface of the piece 18 that constantly comes into contact with this disk-shaped bulge 122 is cylindrical. Therefore, the piece 18 moves in the z1 direction regardless of the tilting direction of the first moving member 12. That is, the seventh
Assuming that the first moving member 12 is tilted so that the spherical center point is displaced by ΔZl in the z1 direction as shown in the figure,
Regardless of the tilting direction, the piece 18 moves by ΔZ2 in the Zt direction.

When an external force acts on the tip of the welding torch in this way,
Regardless of the direction in which the external force is applied, the piece moves in a fixed direction, that is, the Z1 direction, and since this piece is formed in a cylindrical shape, when the bulging portion 122 is tilted, the cylindrical piece 18 will not swell. Exit part 1
Regardless of the tilting direction of 22, it is largely displaced in the z1 direction. By appropriately selecting the output state of the detector that detects the position of the piece in the axial direction, it is possible to detect an abnormal state of the welding torch in any direction with a single detector.

Further, since the cylindrical piece 18 is approximately coaxial with the cylindrical part 132 of the second moving member 13 and is displaced only in the axial direction, a single detector is required to detect the position of the cylindrical piece 18. It is easy to arrange the apparatus, and the space required for the apparatus in the radial direction, that is, in the X direction and the Y direction, is small, so that the apparatus can be made more compact.

Further, since the degree of play between the first moving member 12 and the second moving member 13 with respect to the bored hole 133 and the degree of play in the X direction of the piece 18 and the first moving member 12 can be appropriately selected. Even if an impact force is applied to the tip of the welding torch, the welding torch, the first moving member, etc. can be freely displaced in the direction of the external force with respect to other members, and there is no risk of damage to each part. . Note that Figures 9 and 10 are equivalent to Figures 7 and 8, respectively.
This is a detailed view corresponding to the figure, but as shown in the figure, even if a welding torch or the like is appropriately displaced by an external force, the consumable electrode wire (not shown) is guided by a flexible guide, so the consumable electrode wire can be moved by other parts. Therefore, when the external force acting on the welding torch, etc. is removed, the welding torch, etc. automatically returns to the initial state shown in FIG. 4. Of course, if an abnormal state of the welding torch is detected, the abnormality signal can be used to interrupt the welding operation or other operations related to the welding operation, or to display an abnormality alarm.

By arranging the detector as described above, there is no risk that the detector will be damaged due to contact with other members. Furthermore, since the movable part of the first moving member and the piece are housed within the cylindrical part of the second moving member, there is no risk of dirt or the like getting mixed in, and therefore the first moving member and piece can move smoothly. maintained. Furthermore, since the first moving member is provided with the bulge and the bottomed portion of the second moving member is formed into a flat surface, manufacturing is easy.

Furthermore, since the axes of the welding torch and the bulging portion of the first movable member are configured to substantially coincide with each other, and the protrusion of each part in the radial direction is relatively small, it is generally difficult to It is often used to target narrow areas, and for this reason it is suitable as a welding robot.

In the above description, an appropriate contact type or non-contact type detector such as a differential transformer, an optical sensor, a magnetic sensor, etc. can be used as the detector. Moreover, the present invention can be expressed as a cylindrical coordinate system,
It can also be applied to an appropriate robot such as a Cartesian coordinate system.

Note that the present invention is not limited to the above embodiments,
Various modifications can be made by replacing each part of the embodiment with an equivalent member or by appropriately combining each part of the embodiment.

<Effects of the Invention> As is clear from the above explanation, according to the present invention, the welding torch is supported so that it does not shift during the operation of the robot, so the desired work can be performed, and the welding Since the torch is configured to be able to tilt and slide freely relative to the movable member, if an external force is applied to the welding torch due to an unexpected factor, the welding torch will be freely displaced in the direction of the external force, resulting in damage to each part. Of course, in this case, the consumable electrode wire is guided by a flexible guide, so the consumable electrode wire does not come into contact with other members, and when the external force acting on the welding torch etc. is removed, , welding torches, etc. will automatically return to their initial state. Moreover, in this case, the cylindrical piece is approximately coaxial with the cylindrical part of the second moving member and is displaced only in the axial direction, and the cylindrical piece is moved along the axis when the bulge part of the first moving member is tilted. Because of the large displacement in the direction, an abnormal state can be detected with a single detector regardless of the direction in which the external force is applied. Moreover, this single detector can be easily arranged, and the space required for the device in the radial direction, that is, in the X direction and the Y direction, is small, so that the device can be made more compact. In addition, in conjunction with the compactness of the device, the axes of the welding torch and the bulging portion of the first movable member are substantially aligned, so that the protrusion of each part in the radial direction is relatively small. Therefore, in general, welding work often involves narrow areas, and for this reason, it is suitable as a welding robot.

Furthermore, although the movable member and the welding torch are configured to be able to tilt and slide relative to each other, they are positioned relative to each other with high precision by the biasing means, so that the robot can perform the desired work. .

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing the main parts of the conventional example, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, Fig. 3 is a perspective view showing the embodiment of the present invention, and Fig. 4 is a 5 is a side view of FIG. 4, FIG. 6 is a schematic diagram of the main part of FIG. 4, and FIGS. 7 and 8 are state explanatory diagrams of FIG. 6. 7 is a diagram when a horizontal external force acts on the first moving member, FIG. 8 is a diagram when a vertically upward external force is applied to the first moving member, and FIGS. 9 and 10. The figure is a state explanatory diagram of FIG. 4, and corresponds to FIG. 7 and FIG. 8, respectively. 11... Moving member, 12... First moving member, 12
2...Bulging part, 123...Convex part, 13...Second
131... Bottomed part, 132... Cylindrical part, 1 8... Piece, 24... Welding torch, 5... Detector.

Claims (1)

[Claims] 1. A welding robot that appropriately controls the position of a movable member consisting of a first movable member that supports a welding torch and a second movable member that supports the first movable member, which has a second movable member. The first movable member is formed into a bottom-shaped cylinder, and a hole passing through the bottomed portion in the axial direction of the cylinder is formed. A direction in which the first moving member tilts in the axial direction of the second moving member and with respect to the axis, with the free end of the moving member facing the bottomed part and the cylindrical part through at least the through hole of the second moving member. A bulge is formed at the free end of the first moving member so as to be movable, and the bulge is in contact with the free end of the first moving member and is substantially coaxial with the cylinder of the second moving member and in the axial direction. A first biasing means disposed with a movable cylindrical piece and biased so that the bulging part of the first moving member comes into contact with the bottomed part of the second moving member, and the cylindrical piece. A second biasing means for biasing the first movable member to abut against the free end of the first movable member is provided, and the second biasing means is welded to a through hole formed substantially in the axial center of the end of the second movable member. A flexible guide connected to the welding torch is provided, a shielding gas connection port is provided in the second moving member, and the shielding gas is introduced into the welding torch through the external space of the flexible guide, and the first moving member A detector is disposed for detecting the position of the piece in the axial direction and outputting an abnormal signal when the member is displaced by a predetermined amount or more with respect to the second moving member against the urging force of the urging means. Welding robot.