JP3107724B2 - Power supply mechanism and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply mechanism and a method for supplying a large current to an electrode rotating around an axis, which is used in a resistance spot welding apparatus.

[0002]

2. Description of the Related Art Hitherto, a resistance spot welding apparatus for joining metal plates (workpieces) by utilizing resistance heating has been known (for example, JP-A-2-274386, JP-A-5-104252). Reference). This resistance spot welding apparatus presses a work to be welded with a pair of upper and lower electrode tips arranged opposite to each other, and presses the work to the electrode tip in a state where the work is pressed. The spot welding is performed by rotating the electrode tip about the axis while energizing. The electrode tip is connected to a rotating shaft (conductor) rotatably supported in the casing, and rotates by a predetermined angle about the axis of the rotating shaft under the rotational driving action of a motor. As described above, by rotating one or both of the pair of electrode tips by a predetermined angle about the axis when applying pressure to the workpiece, an oxide film formed on the surface of the workpiece can be removed. Is obtained.

A power supply mechanism according to the prior art for supplying a large current to the electrode tip is considered as follows, similarly to seam welding.

For example, as shown in FIG. 5, first to third brush members 3a to 3c are supported by a plurality of coil springs 2a to 2f engaged with a casing 1, and the first to third brush members are supported. 3a to 3c are rotating shafts (conductors) 4
It is arranged along the outer peripheral surface of. The first to third brush members 3a to 3c are formed of a conductive material, and are electrically connected to a power supply. In this case, the inner peripheral surfaces of the first to third brush members 3a to 3c are configured to be in surface contact and pressure contact with the outer peripheral surface of the rotating shaft 4 by the resilient force of the coil springs 2a to 2f. Therefore, the first to third brush members 3 a to 3
c through the rotating shaft 4 that slides on the rotating shaft 4
A large current can be supplied to the electrode tip connected to the electrode tip.

[0005]

However, in the power supply mechanism according to the prior art devised by the present applicant, the sliding surfaces of the first to third brush members 3a to 3c that come into surface contact with the rotating shaft 4 are long. There is a concern that wear may deteriorate due to the use of time, and that durability may deteriorate, and that a poor power supply state may not be obtained due to a failure in obtaining a good surface contact state.

Further, there is a disadvantage that the number of parts is increased due to the complicated configuration, and it is not easy to manufacture.

Further, the rotating shaft 4 is provided with the coil spring 2
the first to third brush members 3a to 3f
As a result, a large load is applied to the motor that rotates the rotary shaft 4. As a result, a motor having a large rotation torque is required, and there is an inconvenience that manufacturing costs increase.

Further, the first to third brush members 3
There is a disadvantage that a battery is formed between a to 3c and the rotating shaft 4, and electrochemical corrosion (electrolytic corrosion) occurs.

SUMMARY OF THE INVENTION The present invention has been made to overcome all of the above-mentioned inconveniences. The present invention has improved durability, prevents power supply failure, and can be manufactured at a low cost with a simple structure. It is an object to provide a power supply mechanism and method.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a resistance spot welding apparatus for performing spot welding by rotating an electrode by a predetermined angle around an axis under the action of a rotary drive source. A rotary shaft formed of a conductive material, coaxially connected to a drive shaft of the rotary drive source, and rotating an electrode in a predetermined direction; A fixed-side power supply terminal that is fixed to the main body of the resistance spot welding apparatus and is electrically connected to a power supply; The other end of the rotation-side power supply terminal is connected to the fixed-side power supply terminal, respectively , to electrically connect the rotation-side power supply terminal and the fixed-side power supply terminal, and that the rotation shaft and One rotation-side power supply terminal
Deflection along the circumferential direction of the rotating shaft due to physical rotation
And a flexible conductor provided to be freely bent .

[0011]

Further, the present invention provides a resistance spot welding apparatus for performing spot welding by rotating an electrode connected to a rotating shaft of a conductive material by a predetermined angle around an axis under a driving action of a rotating drive source. A power supply method for supplying a current to an electrode, comprising: a fixed-side power supply terminal fixed to a main body of the resistance spot welding apparatus; and a rotation-side power supply terminal connected to the rotation shaft and integrally rotating with the rotation shaft. And a flexible conductor that electrically connects the fixed-side power supply terminal and the rotation-side power supply terminal. The rotation shaft and the rotation-side power supply terminal are integrally rotated under the driving action of the rotation drive source. By moving
Thus, the flexible conductor is energized to the rotating shaft in a state of being bent along the circumferential direction of the rotating shaft.

[0013]

In the power supply mechanism and method according to the present invention,
A large current is supplied to the electrode under the pressurizing action on the workpiece,
The electrode is rotationally displaced by a predetermined angle via a rotary shaft under the driving action of a rotary drive source. As a result, the object to be welded is melted by resistance heating to form a nugget, and the object to be welded is firmly joined.

When the electrode rotates in a predetermined direction, the rotation-side power supply terminal held on the rotation shaft also rotates integrally. The flexible conductor having one end connected to the rotation-side power supply terminal and the other end connected to the fixed-side power supply terminal is bent along the circumferential direction of the rotation shaft without contacting the rotation shaft . In this state, the fixed-side power supply terminal and the rotation-side power supply terminal are electrically connected.

Accordingly, since no member is provided for sliding contact with the rotating shaft, the member is not worn and the durability can be improved. Further, current can be reliably supplied to the rotating shaft connected to the electrode, and power supply failure can be prevented.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the configuration of a power supply method according to the present invention.

FIG. 1 is a schematic configuration diagram of a resistance spot welding apparatus incorporating a power supply mechanism according to an embodiment of the present invention.
FIG. 2 is a sectional view taken along the line II-II shown in FIG. 1.

The resistance spot welding apparatus 10 includes a column 12 erected on a base (not shown), a cylinder 14 fixed on the column 12 and pressurizing an upper electrode 34 described later, And a spot welded portion 16 displaced in the vertical direction under the driving action of the motor 14.

The spot weld 16 includes a cylinder 14
Connected to the tip of a piston rod 18 extending from
A substantially L-shaped bracket 20 displaced in the vertical direction under the action of displacement of the piston rod 18, a torque motor 24 fixed to the bracket 20 via a fixing member 22,
A guide block 30 connected to the bracket 20 and defining guide holes 28a and 28b through which a plurality of guide rods 26a and 26b fixed to a lower side of the column 12 are inserted;

Further, the spot welding portion 16 is connected to a motor shaft 32 of the torque motor 24, and transmits a rotational driving force of the torque motor 24 to the upper electrode 34; And a power supply mechanism 38 for supplying a large current from the upper electrode 34 to the upper electrode 34. A lower electrode 42 is provided on the side opposite to the upper electrode 34 with the workpiece 40 therebetween,
The lower electrode 42 is rotatably held at a predetermined angle around the axis by a rotating means (not shown), and is provided so as to be vertically displaceable by a displacing means (not shown). The lower electrode 42 may be provided so as to be fixed at a predetermined position on a base (not shown).

The driving force transmission mechanism 36 has a casing 44 made of an insulating material, and the casing 44 is supported by a support member 46 made of a conductive material. The support member 46 is connected to the bottom surface of the guide block 30 and is displaced integrally with the bracket 20 in the direction of the arrow under the displacement of the piston rod 18. A flexible electric conductor 48 is provided between the support member 46 and the support 12 and connected to a power supply (not shown), and the electric conductor 48 and the support member 46 are electrically connected.

The power supply mechanism 38 is fixed to an upper portion of substantially the center of the support member 46 and is formed of a first power supply terminal block (fixed power supply terminal) 50 made of a conductive material. An ounce copper plate (flexible conductor) 54 having one end connected to the upper portion via a bolt 52 and having flexibility and conductivity, and a second power supply terminal block (connected to the other end of the ounce copper plate 54) (Rotation side power supply terminal) 56
(See FIG. 2). In this case, the second power supply terminal block 56 is connected to the cylindrical member 6 connected via the bolt 58.
It is provided so as to be integrally rotatable in a predetermined direction together with 0. Therefore, the support member 46 and the cylindrical member 60 are electrically connected through the first power supply terminal block 50, the ounce copper plate 54, and the second power supply terminal block 56 fixed to the support member 46.

Further, the driving force transmission mechanism 36 is coaxially connected to the motor shaft 32 of the torque motor 24, rotates integrally with the motor shaft 32, and has a rotating shaft 62 formed of a conductive material. A case head 64 made of an insulating material is mounted on an upper portion of the casing 44,
Further, a support member (not shown) made of an insulating material is provided between the casing 44 and the rotating shaft 62.

The lower end of the rotary shaft 62 is formed to gradually increase in diameter, and the upper electrode 34 is fitted and pressed into a tapered hole defined on the bottom surface of the rotary shaft 62. . Accordingly, the upper electrode 34 rotates in a predetermined direction integrally with the rotating shaft 62 connected to the motor shaft 32 under the driving operation of the torque motor 24, and also together with the support member 46 under the driving operation of the cylinder 14. Displaces vertically in one.

The resistance spot welding apparatus 10 in which the power supply mechanism 38 according to the embodiment of the present invention is incorporated is basically configured as described above. Next, the operation and the operation and effect will be described. .

First, setting conditions in the resistance spot welding apparatus 10 will be described.

An aluminum alloy plate having a thickness of 1.0 mm and two aluminum alloy plates stacked on each other are used as the workpiece 40, and the upper and lower electrodes 34 and 42 are formed of an alloy material of chromium and copper. And those with a rounded tip portion of 80R were used.

The pressure applied to the workpiece 40 is 350 kgf, and the current supplied from a power source (not shown) is 1
6 kA, the rotation angle (θ ₁ , θ ₂ ) of the upper electrode 34 rotated about the axis by the torque motor 24 is 15 degrees or more.
It was set at 20 degrees.

Further, using a commercial power supply having a frequency of 50 Hz, the squeezing time was (40/50) = 0.8 seconds, the energizing time was (5/50) = 0.1 seconds, and the forging time was (20/5).
0) = 0.4 seconds. The squeezing time refers to the time during which the upper and lower electrodes 34 and 42 are pressed against the workpiece 40, and the forging time refers to the welding time in which the electrodes are melted by resistance heating after energization. Object 4
It is the time that holds 0.

Under these setting conditions, the cylinder 1
Under the driving action of 4, the support member 46 is displaced downward via the bracket 20 connected to the piston rod 18 and displaced downward so that the upper electrode 34 comes into contact with the workpiece. Similarly, the displacement means (not shown) is urged to bring the lower electrode 42 into contact with the workpiece 40, and the upper and lower electrodes 34 and 42 allow the workpiece 40 to be welded.
Is pressurized at a predetermined pressure.

Under a pressurizing action on the workpiece 40, a power source (not shown) is energized to energize the upper electrode 34, and the torque motor 24 is driven to drive the upper electrode 34 connected to the rotating shaft 62. It is displaced by a predetermined angle in a predetermined direction. As a result, the object to be welded 40 is melted by resistance heating to form a suitable nugget, and the object to be welded 40 is firmly joined.

Here, a power supply path from the power supply to the upper electrode 34 will be described. Support 12 from power supply not shown
Current is supplied to the conductor 48 supported by the support member 46, and the current flows through the support member 46, the first power supply terminal block 50, the ounce copper plate 54, the second power supply terminal block 56, the cylindrical member 60, and the rotating shaft 62. It is supplied to the side electrode 34.

The rotating shaft 6 is driven by the torque motor 24.
When the rotating member 2 rotates in a predetermined direction, the cylindrical member 60 and the second power supply terminal block 56 fitted to the rotating shaft 62 are integrally rotated by the rotation angle θ ₁ or θ ₂ (FIG. 3).
And FIG. 4). In this case, the first power supply terminal block 5
Since the ounce copper plate 54 connected between the first power supply terminal block 56 and the second power supply terminal block 56 has flexibility, it flexes as shown in FIG. 3 or FIG. There is no contact with the rotating shaft 62.

Therefore, in the power supply mechanism 38 according to the present embodiment, since there is no sliding surface as compared with the conventional sliding type shown in FIG. 6, the durability can be improved without abrasion. In addition, since power is reliably supplied, power supply failure does not occur.

Further, since the both ends of the ounce copper plate 54 are connected by the first and second power supply terminal blocks 50 and 56, respectively, a simple mechanism is employed.
The number of parts is reduced, and it can be manufactured at low cost.

Further, since a large load is not applied to the torque motor 24 connected to the rotating shaft 62, a motor having a large rotating torque is not required, and in this regard, the manufacturing cost can be reduced.

Further, since there is no sliding surface, no electrochemical corrosion occurs.

In the present embodiment, the first power supply terminal block 50 on the fixed side and the second power supply terminal block 56 on the rotating side are connected by the ounce copper plate 54. However, the present invention is not limited to this. Any conductor having flexibility may be used.

The rotation angles θ ₁ , θ of the upper electrode 34
₂ is not limited to the above set value, but is determined by various factors such as the material of the workpiece 40, the plate thickness, the pressing force, and the flowing current, and is set in the range of 0 to 360 degrees. It is possible to

Further, the power supply mechanism 38 according to this embodiment is
For example, the present invention can be applied to a device for welding by pressing with one electrode, such as stud welding.

[0041]

According to the power supply mechanism and method according to the present invention, the following effects can be obtained.

That is, in comparison with the sliding type such as the brush member according to the prior art, the power supply mechanism and the method according to the present invention have no sliding surface with respect to the rotating shaft, so that they do not wear and have improved durability. In addition to being able to improve the power supply, it is possible to prevent the occurrence of the power supply failure because the power is reliably supplied.

Further, since the flexible conductor is constituted by a simple mechanism in which both ends of the flexible conductor are connected by the rotation-side power supply terminal and the fixed-side power supply terminal, it is possible to reduce the number of parts and manufacture the device at low cost. .

Further, since a large load is not applied to the rotary drive source connected to the rotary shaft, a rotary drive source having a large rotary torque is not required, and in this regard, the manufacturing cost can be reduced. .

Further, since there is no sliding surface as described above, there is no occurrence of electrochemical corrosion.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a resistance spot welding apparatus incorporating a power supply mechanism according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is an explanatory view showing a state in which the state shown in FIG. 2 is displaced by an angle θ in a predetermined direction.

FIG. 4 is an explanatory view showing a state in which the state shown in FIG. 2 is displaced by an angle θ in a predetermined direction.

FIG. 5 is an explanatory view showing a power supply mechanism according to a conventional technique devised by the present applicant.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Resistance spot welding apparatus 12 ... Column 14 ... Cylinder 16 ... Spot welding part 18 ... Piston rod 20 ... Bracket 24 ... Torque motor 30 ... Guide block 34 ... Upper electrode 36 ... Driving force transmission mechanism 38 ... Power supply mechanism 40 ... Weld object 42 Lower electrode 44 Casing 46 Support member 48 Conductor 50, 56 Power supply terminal block 54 Ounce copper plate 60 Cylindrical member 62 Rotation shaft

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B23K 11/11 530 B23K 11/30 307 B23K 11/24-11/24 400

Claims (4)

(57) [Claims] 1. A power supply mechanism incorporated in a resistance spot welding apparatus for performing spot welding by rotating an electrode about an axis by a predetermined angle under the driving action of a rotary drive source, the power feeding mechanism being formed of a conductive material, Coaxial with the drive shaft of the rotary drive source
A rotating shaft that is connected in a shape to rotate the electrode in a predetermined direction, a rotating-side power supply terminal that is fixed to the rotating shaft, and that rotates integrally with the rotating shaft, and is fixed to the main body of the resistance spot welding apparatus. It is, power source and electrically connected to the fixed side power supply terminal, one end the other end in the rotation-side power supply terminals are respectively connected to the stationary power supply terminals, the rotation-side power supply terminal and a fixed-side power supply terminal While being electrically connected, the rotation shaft and the rotation-side power supply terminal are integrated under the driving action of the rotation drive source.
To bend along the circumferential direction of the rotating shaft.
And a flexible conductor provided at least in part. 2. The power supply mechanism according to claim 1 , wherein the flexible conductor is an ounce copper plate. 3. A mechanism according to claim 1 or 2, wherein the rotation-side power supply terminal includes a portion of the cylindrical body which is fitted to the rotary shaft connected to a drive shaft of the rotary drive source, flexible conductors the A power supply mechanism characterized in that one end is flexibly fixed to a side wall of the rotation-side power supply terminal. 4. An electric current is applied to said electrode of a resistance spot welding apparatus for performing spot welding by rotating an electrode connected to a rotating shaft of a conductive material by a predetermined angle around an axis under a driving action of a rotating drive source. A method of supplying power, comprising: a fixed-side power supply terminal fixed to a main body of the resistance spot welding apparatus; a rotation-side power supply terminal connected to the rotation shaft and integrally rotating with the rotation shaft; And a flexible conductor that electrically connects the rotation-side power supply terminal and the rotation-side power supply terminal .
And the rotation-side power supply terminal integrally rotates, so that the flexible conductor is energized to the rotating shaft in a state of being bent along the circumferential direction of the rotating shaft. .