JPH11320115A - Spot welding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of chip deposition and chip dropping by rotating the tip end of arms, after welding is completed, as the rotation shafts, wherein the arms protruding towards a welding piece, and welding chips to be installed at the tip end of the arms are equipped. SOLUTION: The spot welding is carried out with a spot welding gun 21, to which the welding chips 31 are installed at both of the tip end, by contacting the chips 31 with joining parts W1, W2 of a piece W to be welded. Then, both arms 23, 23 tip ends are made to be rotated with the tip end cores as the rotating shafts. By doing so, one or both of welding chips 31 are twisted at the contacting points with the welding piece W within a range of 10-30 deg., and are separated from the welding piece W even when they are deposited with the welding piece W. Twisting of 10 deg. or less is not sufficient to release the deposition. The twisting operation of 30 deg. or more is not desirous, as a moving volume of the arms 23 becomes too large.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Industrial applications]

[0002] The present invention relates to a spot welding machine. More specifically, the present invention relates to a spot welding machine having a function of preventing a chip for welding from coming off. More specifically, the present invention relates to a spot welding machine having a function of preventing a welding tip from being welded to an object to be welded during welding and preventing the welding tip from coming off.

[0003]

[Prior art]

Conventionally, a spot welding gun using a welding tip has been used, for example, by being attached to the tip of a Z-axis for restricting the movement of a welding gun 101 in a horizontal direction by an XYZ three-axis welding robot. The welding tip is attached by covering the electrode tip at the tip with a tapered portion having a tapered structure at the tip of the tip base. Two spot welding guns having a welding tip having such a structure are installed facing each other, are brought close to each other, and the welding operation is performed.

At the end of the welding operation, both ends of the spot welding gun 101 are opened left and right as shown in FIG.
To move to the next hitting position. At this time, if the welding tip 103 is welded, the workpiece 102 is pulled as shown in FIG. 6 as the spot welding gun moves. However, because the workpiece 102 is heavy,
It does not move with the spot welding gun 101.
Further, spot welding gun 101 cannot detect welding.
7, the welding tip 103 comes off from the spot welding gun 101 as shown in FIG. 7, causing damage such as outflow of cooling water.

[0006] This relationship is explained as follows. Taper fitting force: Fg (tensile strength) Bonding force due to welding: Fs (tensile strength) Chip tensile force due to Z-axis rise: Ft Z-axis reduction ratio: G Z-axis pinion gear radius: d offset (Driving force Welding point distance): L Ft = M · G ⁻¹ d / L (N · m) When Fg <Ft Fg <Fs, chip omission occurs. In other words, (motor thrust)> (joint tensile strength)> (taper part fitting force) can be easily imagined.

[0007]

[Problems to be solved by the invention]

Conventionally, to avoid such chipping, measures have been taken to reduce welding conditions so as not to cause welding. However, when the welding conditions are reduced, there is a problem that a problem of welding quality occurs. On the other hand, an apparatus for detecting the outflow of the cooling water circulated to cool the inside of the welding tip by removing the welding tip has also been attempted. But,
In the device for detecting that the welding tip has come off, the welding tip has already come off, so it is necessary to re-fit the welding tip, which has the problem that it takes time to recover.

[0009] On the other hand, if the tensile strength of the joint is set to 1, the shear strength is about 70% of the tensile strength (see Mechanical Design Manual). That is, it is possible to separate the joint with a smaller force by twisting than by pulling. Therefore, 10 ° around the center of the welding tip so that (taper fitting force)> (motor thrust)> (joint shear force).
It has been found that by slightly rotating the welding tip by about 30 °, the welding tip can be more easily separated from the workpiece than by pulling the welding tip away from the workpiece.
Here, the taper fitting force refers to a force when a welding tip is fitted to the arm tip having a tapered frustoconical tip.

[0010]

[Means for Solving the Problems]

The present invention is characterized in that a spot has an arm protruding in the direction of an object to be welded, and a welding tip attached to the tip of the arm, and is rotated about the tip of the arm after welding as a rotation axis. Welding machine, provide. For this reason, after the spot welding is performed by contacting the welding tip to the workpiece by the spot welding machine having the welding tip attached to the tip, the arm tip is rotated using the tip of the arm as a rotation axis. Then, the welding tip is separated from the workpiece even if it is twisted and welded to the workpiece at the point of contact with the workpiece.

Further, the present invention has two arms which are bent at a base end and project in the direction of an object to be welded with their ends facing each other, and welding tips respectively attached to the arm ends. There is provided a spot welding machine characterized by rotating each arm tip about a rotation axis after welding. Therefore, after the spot welding by the spot welding gun in which the welding tips are attached to both ends, the welding tips are brought into contact with the workpiece, the arms are rotated with the tips of both arms as rotation axes. Then, one or both of the welding tips are separated from the workpiece even if they are twisted and welded to the workpiece at the point of contact with the workpiece.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a partially enlarged front view of an embodiment of the present invention, FIG. 2 is an enlarged side view of the same part, FIG. 3 is a perspective view, and an enlarged sectional view of the welding tip. Will be described with reference to FIG.

Reference numeral 11 denotes a welding robot. The welding robot 11 includes a 6-axis robot 11 of XYZ 4, 5, and 6. Reference numeral 12 denotes the X axis of the six-axis robot 11, 13 denotes the Y axis of the six-axis robot 11, and 14 denotes the Z axis of the six-axis robot 11. Reference numeral 15 denotes a robot controller 15, which controls the operation of the welding robot 11 composed of a six-axis robot.

Reference numeral 21 denotes a spot welding gun. The spot welding gun 21 is attached to the tip of the welding robot 11 and includes two arms 23 rotating around a rotation shaft 22 as a rotation center. The arm 23 includes a base 24 extending in a substantially vertical direction, and a distal end 25 protruding in the direction of the workpiece in a direction substantially perpendicular to the workpiece 24 in the base 24. The tip of the tip 25 is tapered. Reference numeral 26 denotes a cooling water passage for cooling. The work W to be welded is made of metal, and in this embodiment, the joint W is projected and shown in FIGS.
1, W2.

Reference numeral 31 denotes a welding tip. The welding tip 31 is fitted to the tip of the arm 23 having a tapered shape.

Accordingly, spot welding is performed by bringing the welding tip 31 into contact with the joining portion W1 and the joining portion W2 of the workpiece W by the spot welding gun 21 having the welding tips 31 attached to both ends. After that, both arms 23, the distal end 25 of the arm 23, and the center of the distal end 25 are rotated around the rotation axis. Then, one or both of the welding tips 31
Is separated from the work W even when it is twisted in the range of 10 ° to 30 ° and welded to the work W at the contact point with the work W.

It is considered that twisting within 10 ° is not sufficient to release welding. A twisting operation exceeding 30 ° is not desirable because the amount of movement of the arm 23 is considered to be too large.

The welding operation and the twisting operation of the welding tip 31 are controlled by a robot controller 15 according to an operation program of the teaching and welding robot 11. That is, after the end of the normal welding program after the instructions of the open state of the arms 23 and 23,
Before moving to the next welding operation point, the robot controller 15 instructs the drive motor of the 6-axis robot 11 to rotate the center of the welding tip 31 attached to the distal end 25 of the arm 23 by 10 ° to 30 °. It rotates and moves to the next target hit point position.

After the completion of the twisting operation, the robot controller 15 instructs the drive motor of the six-axis robot 11 to perform the operation of separating the welding tips 31 from each other. When this occurs, the robot controller 15 determines that welding has occurred. Therefore, an alarm is transmitted to notify the occurrence of welding.

Therefore, the occurrence of welding can be prevented, and the welding can be easily released.

[0022]

According to the present invention, the welding quality is maintained to prevent the occurrence of welding without lowering the welding conditions, and the chipping of the welding tip is prevented.

[Brief description of the drawings]

FIG. 1 is a partially enlarged front view of an embodiment of the present invention.

FIG. 2 is a partially enlarged side view of the embodiment of the present invention.

FIG. 3 is a perspective view of an embodiment of the present invention.

FIG. 4 is an enlarged sectional view after a welding tip according to the embodiment of the present invention;

FIG. 5 is a partially enlarged side view of an operation state of a conventional example.

FIG. 6 is a partially enlarged side view of an operation state of a conventional example.

FIG. 7 is a partially enlarged side view of an operation state of a conventional example.

[Explanation of symbols]

 23 Arm 24 Base 31 Welding Tip W Workpiece

Claims (2)

[Claims] 1. A spot welding machine having an arm protruding in the direction of an object to be welded and a welding tip attached to the arm tip, and rotating the arm after welding by using the arm tip as a rotation axis. . 2. The arm has two arms bent at the base end and projecting toward the work to be welded with the ends facing each other, and welding tips respectively attached to the arm ends. A spot welding machine characterized in that the tip is rotated about a rotation axis.