JP2501307Y2 - Connection unit for energizing welding robots - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention electrically connects the connecting electrode on the moving member side and the connecting electrode on the fixed member side when the movable electrode of the welding robot is moved to a predetermined welding position. The present invention relates to an improvement of an energizing connection unit that is connected to energize a welding current.

Conventional technology One type of welding robot that automatically performs welding work on a workpiece. One pole (eg, plus) side from the transformer is connected to the movable electrode at the tip of the robot arm, and the other pole (eg, minus) side is the work piece. Some are connected to the jig side fixed electrode at the bottom. In addition, such a welding robot is generally configured such that the entire movable portion including the movable electrode performs swivel movement, linear reciprocating movement, and the like with respect to a base member whose position is fixed. Therefore, in order to make the connection for energization as described above, it is necessary to provide a means for electrically connecting the connection electrode on the moving member side and the connection electrode on the fixed member side in the robot. The moving-side connecting electrode is attached over the relative moving range, the fixed-side connecting electrode that is capable of contacting the moving-side connecting electrode is attached to the fixed member, and the moving member and the fixed member are energized. An energizing connection unit or the like is used that electrically connects the fixed-side connecting electrode to the moving-side connecting electrode in a state of being positioned in an appropriate positional relationship by pressing and contacting the fixed-side connecting electrode in a direction perpendicular to the relative movement direction. ing.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention By the way, when performing welding work by the above-mentioned welding robot, after moving the movable electrode of the robot arm to a predetermined welding position, the movable electrode is pressed against the work with a predetermined pressure. It is necessary to pressurize the robot, but the movable part of the robot may be slightly moved by the pressurizing reaction force depending on the pressurizing condition at that time. Therefore, if the moving-side connecting electrode and the fixed-side connecting electrode are pressed into contact with each other before the work is pressed by the movable electrode, the connecting electrodes are relatively moved while being pressed in contact with each other. The contact parts are abnormally worn and their contact surfaces are impaired, resulting in a decrease in energizing current or a significant decrease in electrode life.

The present invention has been made in view of the above circumstances, and its purpose is to ensure that even if a slight positional deviation occurs between members provided with a pair of connection currents, the connection electrodes are not separated from each other. An object of the present invention is to provide an energization connection unit in which relative movement hardly occurs.

Means for Solving the Problems In order to achieve such an object, the gist of the present invention is to move a movable electrode to a predetermined welding position and sandwich a work between the fixed electrode and a fixed electrode. In a welding robot that performs spot welding by pressing, when the movable electrode is moved to the welding position, the movable member and the fixed electrode side of the welding robot that are moved when the movable electrode is moved to the welding position. A welding transformer disposed on any one of the fixed members, and an energization connection unit for electrically connecting a welding current by electrically connecting the movable electrode or the fixed electrode on the other member side,
(A) a first connecting electrode attached to a first member of one of the moving member and the fixed member; and (b) a second connecting member of the moving member and the other second member of the fixed member. A second connection electrode attached to correspond to the movement range; (c) a slide member disposed on the first member so as to be movable in a direction substantially parallel to the movement direction of the movement member; Urging means that is disposed between the first member and the slide member and that always holds the slide member at a neutral position in the moving direction of the moving member; and (e) the slide member, the moving member. Is arranged so as to be movable in a direction substantially perpendicular to the moving direction of the first connecting electrode and is moved toward the second connecting electrode, and is pressed against the second connecting electrode by the driving means provided on the slide member and from the second connecting electrode. Third separated A continuous electrode; and (f) a conductive member that electrically connects the third connection electrode and the first connection electrode while allowing relative movement of the third connection electrode with respect to the first connection electrode. It is in.

By doing so, in the connection state in which the movable electrode is moved to the welding position by the moving member of the welding robot and then the third connecting electrode is pressed against the second connecting electrode by the driving means, the spot welding pressure is applied. When the moving member is slightly displaced by the reaction force, that is, when the first member and the second member, which are one and the other of the moving member and the fixed member, are relatively moved in the moving direction of the moving member, The third connection electrode, which is movable relative to the first member together with the slide member, is moved relative to the first member by moving together with the second connection electrode. At this time, the conduction between the first connection electrode and the third connection electrode is maintained by the conductive member regardless of the movement of the third connection electrode in the pressing direction and the relative movement direction. Further, when the third connection electrode is separated from the second connection electrode after the energization is completed, the slide member is returned to the neutral position by the urging means.

EFFECTS OF THE INVENTION As described above, in the energizing connection unit of the present invention, the third connection electrode pressed by the second connection electrode is disposed on the slide member, and the third connection electrode is arranged relative to the first member in the moving direction of the moving member. Since it is designed to be movable, as in the conventional energizing connection unit in which such relative movement is not allowed, the connecting electrodes are moved relative to each other while being pressed and contacting each other. The problem that abnormal wear occurs, the contact surfaces thereof are damaged, the energization current is reduced, and the life of the electrode is significantly reduced is solved.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a front view of a spot welding robot 12 provided with an energization connection unit 10 according to an embodiment of the present invention. This robot 12 is a vertical multi-joint type 5-axis robot, and has a turning axis 14, a longitudinal axis 16, and a vertical axis 1 connected in series.
It is equipped with five actuating shafts, an arm pivot shaft 20, and a wrist bending shaft 22.

The swivel shaft 14 is arranged rotatably around a substantially vertical center line l ₁ on a base 24 via a table 15 to which the swivel shaft 14 is integrally fixed. The front-rear shaft 16 is arranged at the tip of the revolving shaft 14 so as to be rotatable around a substantially horizontal center line l ₂ . The vertical shaft 18 is disposed at the tip of the front-rear shaft 16 so as to be rotatable around a center line l ₃ parallel to the center line l ₂ . The arm pivot shaft 20 is arranged so as to be rotatable around a center line l _{4 which} is perpendicular to the center line l _{3 while} protruding from the tip end of the vertical shaft 18. The wrist bending shaft 22 is arranged at the tip of the arm turning shaft 20 so as to be rotatable around a center line l ₅ orthogonal to the center line l ₄ .

The rotating shaft 14 is configured to be rotated within a predetermined operating range by an electric motor 26 with a position sensor, which is connected via a speed reducer (not shown). The front and rear shafts 16 and the vertical shafts 18 are adapted to be rotated by brake cylinders 28 and 30 with position sensors within predetermined operating ranges. The arm turning shaft 20 and the wrist bending shaft 22 are adapted to be rotated by electric motors 32 and 33 with position sensors within predetermined operating ranges. The brake cylinders 28 and 30 have a brake mechanism integrally attached to the tip end thereof so that the rod can be stopped from moving in and out.

A stud gun 34 for welding is attached to the wrist bending shaft 22 in a posture orthogonal to the rotation center line l ₅ . The stud gun 34 has a movable electrode 40 attached to the tip of an output rod 38 of a reciprocating pressure cylinder 36, and is fixed to the wrist bending shaft 22 at the rear end of the pressure cylinder 36. The movable electrode 40 includes an energizing cable 42 and an energizing bar 4
It is connected to the + terminal of the welding transformer 50 placed on the table 15 through 4,46 and the energizing cable 48 in this order. The current-carrying bars 44, 46 are rotated by the connecting tool 52 so as to rotate around the center line.
They are connected so as to be rotatable relative to each other about a center line parallel to l ₂ and l _3, and the center lines l ₂ and
The pins are attached to the vertical shaft 18 and the turning shaft 14 so as to be relatively rotatable around pins 54 and 56 parallel to l ₃ .

On the other hand, the pair of works 58, 60 to be welded are positioned and placed on the positioning jig 62, and the fixed electrodes 64 are provided below the welding positions of the works 58, 60. There is. The fixed electrode 64 is connected to the energizing connection unit 10 via an energizing cable 66, and when the energizing connecting unit 10 is brought into a connected state, one of the transformer 50 is connected via the energizing cable 95. Connected to the terminal. The illustrated parts of the works 58 and 60 are parts to be welded in the vertical direction, and the pressurizing direction by the pressurizing cylinder 36 is also performed in the vertical direction. Since the welding direction is not necessarily vertical at the location, the pressure direction by the pressure cylinder 36 may not be vertical.

The main unit of the connection unit 10 for energization is the robot 12
1 and 2 in detail, a front view and a right side view of the energization connection unit 10 attached to the side of the base 24 which is a stationary member in FIG. Mounting base integrally provided on the base 24
A guide rail 70 is fixed to the 68 in the horizontal direction by bolting, and a slide portion 74 integrally provided with a pair of upper and lower slider blocks 72 engaging with the guide rail 70 is provided in the horizontal direction, that is, The table 15 that moves with respect to the base 24 as the swivel shaft 14 rotates is slidable in the relative movement direction. The slide portion 74 corresponds to the slide member in this embodiment.

The sliding portion 74 includes a first frame 71 to which the upper slider block 72 is fixed, a second frame 73 to which the lower slider block 72 is fixed, and between the first frame 71 and the second frame 73. Air cylinder clamped and fixed
It is composed of 88 and. The slide portion 74 is always sandwiched by the compression coil springs 80 and 82 disposed at both ends of the guide rail 70 via the brackets 76 and 78 from both sides and is biased, so that the slide portion 74 is always in its neutral position. Is held in the center of the guide rail 70. In the present embodiment, the compression coil springs 80 and 82 correspond to the biasing means. A first connecting electrode 86 is fixed to a portion of the bracket 78 extending laterally via an insulating plate 84, and one end of the energizing cable 66 is connected to the first connecting electrode 86. In this embodiment, the base 24 is a fixed member on the fixed electrode 64 side and corresponds to the first member.

The air cylinder 88 of the slide portion 74 is arranged with its axial direction up and down, and when the air is supplied from an air supply source (not shown), the rod 88a is driven up and down. . An electrode holding portion 90 that is lifted by the operation of the air cylinder 88 is attached to the tip of the rod 88a. The electrode holding portion 90 is the rod 88a.
And a holder 94 and the like which are provided above the plate 92 so that they can approach each other. On the holder 94, the third connection electrode 98 located directly below the second connection electrode 96 is bolted through the fourth connection electrode 100 and the insulating plate 102 integrally connected to the third connection electrode 98. It is fixed by tightening. The second connection electrode 96 has the third connection electrode 96 below the cable 15 that rotates together with the swivel shaft 14 and over the relative movement range.
The table is formed in an arc shape so that 98 can contact
It is attached to the lower surface of 15 and is connected to one terminal of the transformer 50 through an energizing cable 95. In this embodiment, the table 15 is a moving member and corresponds to a second member.

The holder 94 is fixed to the plate 94 by a pair of bolts 104 fixed to the holder 94 and penetrating the plate 92, respectively.
Is guided so as to be movable relative to the vertical direction with respect to, and is always positioned at the upper end of the relative movement stroke by being biased by the compression coil spring 106 interposed between the plate 92 and the holder 94. Has been made. Therefore, when the air cylinder 88 is operated and the third connection electrode 98 is pressed into contact with the second connection electrode 96 immediately above, the impact at the time of contact is softened by the compression coil spring 106, and The plate 92 and the holder 94 resist the urging force of the compression coil spring 106.
And the upper surface of the third connecting electrode 98 is pushed by the pressing force equal to the repulsive force of the compression coil spring 106.
The lower surface of 96 is pressed and brought into surface contact. In this embodiment, the air cylinder 88 corresponds to the driving means.

It should be noted that the plate 92 is axially fitted to a shaft 108 provided upright at one end of the slide portion 74 via a bush 109, so that the air cylinder of the plate 92 itself.
Rotation around the axis of 88 is blocked. Further, a steadying member 110 that is slidably engaged with the shaft 108 in the vertical direction is attached to one end of the holder 94, and the core runout of the holder 94 is restricted. Further, inside the fourth connection electrode 100, there is formed a passage 100a for circulating a coolant for suppressing a temperature rise due to a large welding current.

Between the first connection electrode 86 and the fourth connection electrode 100,
A booth bar 112 for electrically connecting the electrodes is arranged so as to straddle the two, and one end and the other end thereof are bolted to the fourth connection electrode 100 and the first connection electrode 86, respectively. . The booth bar 112 is formed by bundling a plurality of elongated copper plates and bending them into a U shape, and is capable of bending deformation in a plane including the thickness direction in common, that is, in a plane parallel to the paper surface of FIG. Has been done. Therefore, as described above, when the third connection electrode 98 is raised until it comes into contact with the second connection electrode 96, one end thereof rises together with the fourth connection electrode 100, and accordingly, in FIG. As indicated by the dotted line, the curved portion is deformed to have a smaller curvature. In this embodiment, the booth bar 112 corresponds to the conducting member.

Next, the operation of the energizing connection unit 10 configured as described above will be described with reference to the welding operation operation of the robot 12.

First, the swivel axis 14, front-rear axis 16, vertical axis 18, arm swivel axis 20,
The wrist bending shaft 22 is rotated by a predetermined rotation amount by the operation of the electric motors 26, 32, 33 and the cylinders 28, 30, respectively.
At a predetermined welding position in a posture that is substantially perpendicular to the surfaces of the works 58, 60. In this state, the turning positions of the turning shaft 14, the arm turning shaft 20, and the wrist bending shaft 22 are positioned by the braking action of the electric motors 26, 32, and 33 by the servo control, and the front and rear shafts 16 and the vertical shafts 18 are rotated. The rotation positions are cylinder 28 and
Positioned by 30 braking devices.

When the positioning of the stud gun 34 is completed, the relative position between the base 24 and the table 15 is positioned, and subsequently, in the energizing connection unit 10, the air cylinder
The electrode holder 90 is raised by the operation of 88 and the third
The connection electrode 98 is pressed into contact with the second connection electrode 96,
The energizing connection unit 10 is brought into a connected state. As a result, the energizing cable 66 passes through the first connecting electrode 86, the booth bar 112, the fourth connecting electrode 100, the third connecting electrode 98, the second connecting electrode 96, and the energizing cable 95, and then the transformer 50 on the robot 12. It will be connected to one terminal of.

Next, the movable electrode 40 is projected by the pressure cylinder 36 of the stud gun 34, and the pair of works 58 and 60 is clamped between the fixed electrode 64. At this time, the pressure applied by the pressure cylinder 36 is usually several hundred kgf, and the work 5
Depending on the welding conditions such as plate thickness and material of 8,60, a pressure of about 700 kgf may be required. Therefore, a pressure reaction force for moving the stud gun 34 in the direction opposite to the pressure direction acts, and the operation shafts of the robot 12 are slightly moved in spite of being pre-positioned. In some cases, when the pressing direction is not the vertical direction parallel to the center line l ₁ , a moment is applied to the swivel shaft 14 and a displacement of about several mm may occur in the outer peripheral portion of the table 15.

When the table 15 is thus displaced, the second connection electrode 96 in the energization connection unit 10 is moved together with the table 15 in either the left or right direction in FIG. Due to the frictional resistance based on the pressing force between the contact surfaces of the second connection electrode 96 and the third connection electrode 98, the slide portion 74 together with the third connection electrode 98 resists the urging force of the compression coil spring 80 or 82. It is horizontally moved in the above-mentioned moving direction. By this operation, the third connection electrode 98 is moved together with the second connection electrode 96,
Almost no relative movement occurs between the second connection electrode 96 and the third connection electrode 98, and the conductive state between these electrodes is maintained well. The booth bar 112 is slightly deformed so as to allow relative movement between the first connection electrode 86 and the fourth connection electrode 100 due to this operation.

Then, when a welding current is output from the transformer 50 in that state, the welding current is supplied to the movable electrode 40 via the energizing cable 48, energizing bars 46, 44 and energizing cable 42, and the work 58, 60, The fixed electrode 64, and the energizing cable 66, the connection unit 10, and the energizing cable 95 are caused to flow to one terminal of the transformer 50. At this time, they are generated based on the heat generated by the electric resistance between the work 58 and the work 60. The workpieces 58 and 60 are welded.

When the welding work is completed in this way, the supply of welding current is stopped and the air cylinder 88 of the energizing connection unit 10 is stopped.
Is operated in the opposite direction, the electrode holding portion 90 is lowered to release the pressed state of the third connection electrode 98, and the output rod 38 of the pressurizing cylinder 36 is pulled in to apply the work 58, 60. The pressure state is released. At this time, the sliding portion 74 of the connection unit 10
It is returned to its neutral position by 82, and each member is returned to the initial state. After that, the electric motors 26, 32,
33, and cylinders 28, 30 for each operating shaft 14, 16, 18, 20,
The stud gun 34 is moved to another welding position by rotating the respective 22 by a predetermined rotation amount, and the above-described welding work is repeated.

As described in detail above, according to the present embodiment, the second
The third connecting electrode 98 pressed by the connecting electrode 96 is the slide portion 74.
Is arranged on the table 15, the third connection electrode 98 moves along with the movement of the second connection electrode 96 with respect to a stationary member such as the first connection electrode 86 due to the displacement of the table 15. It is possible to move in the direction,
The booth bar 112 while allowing the movement of the third connection electrode 96.
Connects the first connection electrode 86 and the third connection electrode 98 to the fourth connection electrode 10
Since it is provided so as to be electrically connected via 0, as in the conventional energizing connection unit in which such relative movement is not allowed, the electrodes can be relatively moved while being in pressure contact with each other. This eliminates the problems that abnormal wear occurs in the contact parts, the contact surfaces are damaged, and the energization current is reduced or the electrode life is significantly reduced.

Although one embodiment of the present invention has been described above with reference to the drawings, the present invention can be applied to other aspects.

For example, in the above-described embodiment, the first connection electrode 86
The booth bar 112 is provided as a conductive member that electrically connects the third connection electrode 98 and the fourth connection electrode 100 to each other while permitting relative movement of the third connection electrode 98 and the fourth connection electrode 100. It may be composed of a pair of current-carrying bars connected by a connector, or a current-carrying cable similar to the current-carrying cable 42 may be used as long as it is safe in terms of electric capacity. The fourth connection electrode
100 does not necessarily have to be provided, and the conductive member is directly connected to the third position.
It may be connected to the connection electrode 98.

Further, in the above-described embodiment, the third connection electrode 98 held by the holder 94 is positioned relative to the plate 92 via the bolt 104 and the compression coil spring 106 in the pressing contact direction with the second connection electrode 96. They were connected so that they could approach each other, and were configured to provide a cushioning effect when pressed,
The holder does not necessarily have to have such a structure.
It does not matter if the rod 88a of the air cylinder 88 is directly connected to 94.

Further, in the above-described embodiment, the compression coil springs 80 and 82 are used as the biasing means,
Instead of these, other spring members such as a tension coil spring, members such as a pendulum that perform a returning operation by utilizing gravity may be used.

Further, in the above-described embodiment, the main body portion of the energizing connection unit 10 including the guide rail 70 is attached to the base 24 side, and the second connection electrode 96 is attached to the table 15 side. On the contrary, the second on the base 24 side
The connection electrode 96 may be attached, and the main body portion of the energization connection unit 10 may be attached to the table 15 side.

In the above-described embodiment, the transformer 50 is placed on the table 15, but the transformer 50 is placed on the base 24 or on the floor to connect the + terminal side. This may be the case where the energizing connection unit 10 is used.

Although not specifically exemplified, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art without departing from the spirit thereof.

[Brief description of drawings]

FIG. 1 and FIG. 2 are a front view and a side view, respectively, in which a part of an energization connection unit according to an embodiment of the present invention is cut away. FIG. 3 is a diagram showing an example of a spot welding robot using the energization connection unit of FIG. 10: Connection unit for energization 12: Robot (welding robot), 15: Table (moving member, second member), 24: Base (fixed member, first member), 40:
Movable electrode, 50: Welding transformer, 58, 60: Work, 64: Fixed electrode 74: Slide part (slide member) 80, 82: Compression coil spring (biasing means) 86: 1st connection electrode 88: Air cylinder ( Driving means) 96: Second connection electrode 98: Third connection electrode 112: Booth bar (conductive member)

Claims (1)

(57) [Scope of utility model registration request] 1. A welding robot for moving a movable electrode to a predetermined welding position and performing spot welding by pinching a work between the movable electrode and a fixed electrode arranged in a fixed position, wherein the movable electrode is moved to the welding position. A welding transformer disposed on either one of the moving member of the welding robot and the fixed member on the fixed electrode side, which is moved when the movable electrode is moved to the welding position when moved; Is a current-carrying connection unit that electrically connects the movable electrode or the fixed electrode on the member side to supply a welding current, and is attached to any one of the first member of the moving member and the fixed member. The first connecting electrode, and the other second member of the moving member and the fixed member,
A second connection electrode attached to correspond to a moving range of the moving member; a slide member movably disposed on the first member in a direction substantially parallel to a moving direction of the moving member; An urging means that is disposed between one member and the slide member and that always holds the slide member at a neutral position in the moving direction of the moving member; A third member which is disposed at a right angle and is movable in a direction toward the second connection electrode, and which is pressed against the second connection electrode by a driving means provided on the slide member and separated from the second connection electrode. A connection electrode; and a conductive member that electrically connects the third connection electrode and the first connection electrode while allowing relative movement of the third connection electrode with respect to the first connection electrode. Welding robot The current-carrying connection unit of the door.