JPH0433545B2 - - Google Patents

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, and therefore, 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 the external force. 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. The welding torch 24' is disposed in the same direction as the welding torch 24', and the welding torch 24' is biased in the _Z2 direction by a spring 55 so that the welding torch can be tilted and moved in the _Z1 direction. Further, a fixed electrode 5 having an arcuate shape is provided at the rear end opening of the movable member 11' via an insulating material 56.
7, and a radially extending first movable electrode 58, 58... and a radially extending second movable electrode 59 are attached to the tail end of the welding torch where this fixed electrode 57 is located. , 59, fixed electrodes 57, and detectors 60, 60 connected thereto.
The contact state of the welding torch was 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. Also, the tip of the welding torch
When a force in the _Z1 direction is applied, the welding torch penetrating the hole in the spherical convex body moves in the _Z1 direction against the spring, and the second movable electrode and the fixed electrode come into contact.

<Problems to be Solved by the Invention> By the way, the welding torch is displaced in the direction in which external force acts, but since the contact state of the welding torch is detected by the contact between the movable electrode and the fixed electrode, the displacement of the welding torch with respect to the moving member is The amount is limited to a very 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 it into at least two parts in the radial or axial direction, but it is troublesome to form the inner surface of the divided spherical concave body into a smooth spherical shape. . Furthermore, when an external force in the Z ₁ direction is applied to the tip of the welding torch, if the hole in the spherical convex body is made larger to allow the welding torch to move smoothly, the positioning of the welding torch will be inaccurate. It had the disadvantage of becoming.

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 bottomed cylinder, 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. when the first moving member moves to the second moving member.
A bulge is formed at the free end of the first movable member so that it is movable in the axial direction of the movable member and in a direction tilting with respect to the axis, and a bulge is formed in the free end of the first movable member so that the second movable member comes into contact with the free end of the first movable member. A cylindrical piece that is substantially coaxial with the cylinder of the movable member and movable in the axial direction is provided, and biased so that the bulging portion of the first movable member comes into contact with the bottomed portion of the second movable member. A first biasing means for biasing the cylindrical piece and a second biasing means for biasing the cylindrical piece so as to contact the free end of the first movable member. A flexible guide is provided to connect the through hole drilled in the shaft core and the welding torch, and a second
A shielding gas connection port is provided in the movable member to introduce the shielding gas into the welding torch through the external space of the flexible guide, and the first movable member resists the biasing force of the biasing means and connects the second movable member to the welding torch. 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 with respect to the moving member.

<Examples> Hereinafter, the present invention will be described in detail with reference to illustrated examples. Now, when talking about the multi-articulated arm type welding robot, in Figures 3 to 5, 1
3 and 4 are lower arms and link levers that are respectively rotatably supported with respect to the underframe 1; 5;
is a rear arm rotatably supported by link lever 4, 6
An upper arm is rotatably supported by a lower arm 3 and a rear arm 5, and the upper arm 6, lower arm 3, link lever 4, and 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 the first and second supports supported by the underframe 1.
In this rotary drive machine, the lower arm 3 is vertically rotated by the first rotary drive machine 7 via a speed reducer, and the upper arm 6
is pivoted in the vertical direction about the axis of the lower arm 3 and upper arm 6 via the link lever 4 and the rear arm 5, which are rotated by the second rotary drive unit 8 via a speed reducer. 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 movable member 11 is supported by the upper arm 6 via, for example, a horizontal rotation mechanism 10, and a suitable consumable electrode type welding torch 24 is supported by the movable member 11. To explain in more detail, the fourth
In the figures and FIG. 5, reference numeral 12 denotes a first moving member that supports a welding torch 24 at one end, and in the illustrated case, the welding torch 24 is screwed onto the first moving member 12. A through hole 121 is formed substantially in the 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. 13 is a second moving member for supporting the first moving member 12;
A bottomed portion 131 and a cylindrical portion 132 are formed. Further, a through hole 133 is bored in the bottomed portion 131, and the bulging portion 122 of the first moving member 12 is connected to the second moving member 13 through this through hole 133.
The flange surface 124 of the bulging portion 122 contacts 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 to be approximately the same as the radius of the cylindrical portion 132, the first moving member 12 can freely tilt and tilt relative to the second moving member 13. Can be slid. Reference numeral 14 denotes a spring holder that locks the compression spring 19, and the compression spring 19 disposed between the spring holder 14 and the first moving member 12 always urges the first moving member 12 in the _Z2 direction. has been done. 15 is a lid body, and this lid body 15 and a spring presser 1
4 are integrally fastened to the second moving member 13,
It is supported by a support bracket 17 via a suitable electrically insulating member 16 and connected to the horizontal rotation mechanism 10. Moving member 1 according to the above 12 to 17
1 is configured. 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. 20 is a compression spring arranged between the lid body 15 and the piece 18, and the piece 18 is always urged in the Z2 direction by this spring force, and the piece 18 is always urged in the _Z2 direction.
It is in contact with the moving member 12 of. 21 is the lid body 15
The flexible guide is disposed between the welding torch 24 and the welding torch 24, and is made of, for example, a spirally formed wire 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 a consumable electrode wire is screwed into a threaded portion 151 screwed onto the lid 15. Also, 22 is a connection port for supplying shielding gas for welding, and this connection port 2
The space communicating with 2 is provided with appropriate airtight members 231, 23.
Blocked by 2,233,234, Z ₂ of piece 18
The welding torch 24 is communicated with the welding torch 24 through a hole 182 drilled at the end of the flexible guide through an external space of the flexible guide. A detector 25 is arranged to detect, for example, the position of the flange portion 181 of the piece 18. Reference numeral 26 indicates a cover having appropriate flexibility such as rubber or synthetic resin, and 27 indicates a power line for welding, which is connected to the lid 15 through an appropriate insulating member.
and then connected to a welding torch.

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, since the bulging portion 122 of the first moving member 12 urged by the spring 19 comes into contact with the bottomed portion 131 of the second moving member 13, the shielding gas supplied from the connection port 22 is 18 and reaches the container torch 24. Further, a consumable electrode wire (not shown) is guided by a flexible guide 21 and fed to a welding position, and welding is performed while power is supplied to a welding torch via a power line 27.

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 state 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. Since the curvature of the curved convex portion 123 of the bulging portion 122 of the first moving member 12 is formed to be approximately the same as the radius of the cylindrical portion 132 of the second moving member 13, the first moving member 12 is Attempt to tilt clockwise. In this case, the first moving member 12 is urged 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. , the spherical center point of the bulge 122; the distance where O ₁ is in the Z ₁ direction; the position where ΔZ ₁ is displaced;
Tilt appropriately with _O2 . In this case, the piece 18 is moved in the _Z1 direction by a distance _ΔZ2 , as shown in FIG. Furthermore, when an external force in the _Z1 direction is applied to the tip of the welding torch, the first
The bulging portion 122 of the moving member 12 is displaced along the cylindrical portion 132 in the _Z1 direction by, for example, a distance _ΔZ3 .

In addition, since the bulging portion of the first moving member 12 is formed in a spherical convex shape, the first moving member 12 can tilt in any direction with respect to the second moving member 13. The bulging portion 122 is formed in a disk shape, and the contact surface of the piece 18 that constantly contacts the disk-shaped bulging portion 122 is formed in a cylindrical shape, so that the tilting member of the first moving member 12 Regardless of the above, the piece 18 moves in the _Z1 direction. That is, if the first movable member 12 is tilted so that the ball center point is displaced by ΔZ ₁ in the Z ₁ direction as shown in FIG. 7, the piece 18 will be displaced by ΔZ ₂ regardless of the tilting direction.
Z Move in _one direction.

When an external force is applied to the tip of the welding torch in this way, the piece moves in a fixed direction, that is, the _Z1 direction, regardless of the direction in which the external force acts.Moreover, since this piece is formed in a cylindrical shape, it expands. When the protrusion 122 is tilted, the cylindrical piece 18 is largely displaced in the _Z1 direction, regardless of the direction in which the protrusion 122 is tilted. By appropriately selecting the output state of the detector that detects the position of the piece in the axial edge direction, it is possible to detect an abnormal state of the welding torch in any direction with a single detector.

Further, the cylindrical piece 18 is connected to the second moving member 13
Since it is approximately coaxial with the cylindrical part 132 and is displaced only in the axial direction, it is easy to install a single detector for detecting the position of this cylindrical piece 18, and the radial direction required for the device is easy. In other words, the space in the X and Y directions is small, so the device can be made more compact.

Moreover, the first moving member 12 and the second moving member 1
Since the play with the drilled hole 133 of No. 3 and the play in the Z direction of the piece 18 and the first moving member 12 can be appropriately selected, if an impact force is applied to the tip of the welding torch, However, there is no risk that the welding torch, the first movable member, etc. may be freely displaced in the direction in which the external force is applied with respect to other members, and that each part will be damaged. Note that FIGS. 9 and 10 are detailed views corresponding to FIGS. 7 and 8, respectively, but as shown,
Even if a welding torch, etc. is displaced appropriately due to an external force, the consumable electrode wire (not shown) is guided by a flexible guide, so the consumable electrode wire does not come into contact with other members, and therefore does not affect the welding torch, etc. When the external force is removed, the welding torch and the like automatically return to the initial state shown in FIG. 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 in 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. is 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 use a narrow space during welding work. There are many cases where the target is a part, and therefore 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, optical sensor, magnetic sensor, etc. can be used as the detector. Further, the present invention can also be applied to an appropriate robot such as a cylindrical coordinate system or a rectangular coordinate system.

It should be noted that the present invention is not limited to the above embodiments, and various modifications can be made by replacing each part of the embodiments with equivalent members or appropriately combining the parts of the embodiments.

<Effects of the Invention> As is clear from the above explanation, according to the present invention, the welding torch is supported so as not to shift during the operation of the robot, so that 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, and each part will be There is no risk of damage, and 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 parts, and removes external forces acting on welding torches, etc. , the welding torch 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,
Since the cylindrical piece is displaced only in the axial direction, and the cylindrical piece is largely displaced in the axial direction when the bulge of the first moving member is tilted, regardless of the direction in which the external force is applied,
Abnormal conditions can be detected with a single detector. Moreover, this single detector is easy to arrange, and the space required for the device in the radial direction, that is, in the X and Y directions, is small, so that the device can be made more compact. In addition, as the equipment becomes more compact, the welding torch and
It is constructed so that the bulges of the moving members and the respective axes approximately coincide with each other, and the protrusion in the radial direction of each part is relatively small, so welding operations often involve narrow areas. Therefore, 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 drawings]

FIG. 1 is a vertical cross-sectional view showing the main parts of the conventional example, FIG. 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 sectional views of FIG.
FIG. 7 is a diagram showing the state when a horizontal external force is applied to the first moving member, and FIG. 8 is a diagram explaining the state of the first moving member.
FIGS. 9 and 10 are diagrams illustrating the state of FIG. 4 when a vertically upward external force is applied to the moving member, and correspond to FIGS. 7 and 8, respectively. 11... Moving member, 12... First moving member,
122...Bulging part, 123...Convex part, 13...
Second moving member, 131... Bottomed portion, 132...
... Cylindrical part, 18 ... Piece, 24 ... Welding torch, 2
5...Detector.

Claims (1)

[Claims] 1 A first moving member that supports a welding torch and a first moving member that supports a welding torch.
In a welding robot that appropriately controls the position of a movable member including a second movable member that supports a movable member, the second movable member is formed into a cylinder with a bottom, and the second movable member is formed into a cylinder with a bottom. A hole penetrating in the axial direction of the cylinder is bored, a through hole is bored approximately at the axial center of the first moving member, and the free end of the first moving member is formed so as to pass through at least the second moving member. A free end of the first movable member is configured to face the bottomed portion and the cylindrical portion through the hole and to be movable in the axial direction of the second movable member and in a direction tilted relative to the axis. A cylindrical piece forming a bulge, abutting the free end of the first moving member, being substantially coaxial with the cylinder of the second moving member and movable in the axial direction; A first biasing means for biasing the bulging portion of the member to abut the bottomed portion of the second movable member, and a cylindrical piece such that the cylindrical piece abuts the free end of the first movable member. A second biasing means for biasing is disposed, a flexible guide is disposed for connecting the welding torch and a through hole drilled approximately at the axial center of the end of the second movable member; A shielding gas connection port is disposed in the movable member to introduce the shielding gas into the welding torch through the external space of the flexible guide, and the first movable member resists the biasing force of the biasing means to introduce the shielding gas into the welding torch. A welding robot equipped with a detector 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 with respect to the moving member.