JPS6316236B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a friction welding method, and particularly to improving cycle time.

Conventionally, a workpiece is gripped by a rotating chuck and a stationary chuck that are in a stopped state, the rotating chuck is rotated, and the pair of workpieces are brought into contact under axial thrust, and the frictional heat generated at that time is used to After softening the vicinity of the joint surface, the rotation is rapidly stopped, and an axial thrust equal to or greater than the axial thrust is maintained for a set time to complete friction welding, and then the welding area is expanded. If it is necessary to remove the protruding burr by cutting, after the friction welding is completed, only the stationary side chuck is released, the rotating side chuck is rotated again at a rotation speed suitable for cutting, and a cutting tool is used as appropriate. The burrs were then removed by cutting.

However, in this conventional method, which transmits the driving force from the motor by being directly connected to the rotating chuck, it wastes time to shift from a stopped state to a rotating state, and it takes a long time to start up rotation from a stopped state. It is difficult to perform repeated operations in a short period of time due to the load placed on the motor, and furthermore, if it is necessary to cut burrs, it is necessary to restart the machine from a stopped state once again. Therefore, there is a natural limit to shortening the cycle time of friction welding processing, and therefore it is impossible to hope for productivity improvement beyond a certain level. In order to stop the vehicle, a braking device must be installed.
This not only complicates the structure of the machine, but also
This meant a rise in cost prices. There is also a known technology that focuses on the time required for the motor to start rotating and is configured to transmit the driving force from the motor to the rotating chuck via a clutch so that the motor is always in a rotating state. However, this method still requires a new clutch, so it has the same drawbacks as mentioned above.If burr cutting is required after friction welding, as mentioned above, extra time is added for this process. In the end, it was difficult to further shorten the cycle time.

The present invention was made for the purpose of eliminating the above-mentioned drawbacks and providing a friction welding method that can significantly improve cycle time with a simple configuration. The machine is constantly rotated at either high or low speed, the work piece is attached and removed during low speed rotation, a frictional heat generation process is performed during high speed rotation, and regenerative braking is utilized by changing the number of poles of the motor at the end of the process. When the set rotation speed reaches the set low speed, the stationary side chuck is released to allow the stationary side workpiece to rotate integrally with the rotating side workpiece, and the workpiece during the frictional heat generation process. Friction welding is performed by applying and sustaining an axial thrust equal to or greater than the axial thrust applied to The process of cutting away the burrs that bulge out is performed in parallel. The present invention will be described in detail below with reference to illustrated embodiments.

In the figure, reference numeral 1 denotes a machine base of a friction welding machine, on which a rotating chuck 2 is rotatably supported, and a stationary chuck 3 can approach and move away from the rotating chuck 2. It is supported so that it can slide in the axial direction. Numerals 4 and 5 are gripping claws provided on each chuck 2 and 3 for gripping the rotating work piece 6a and the stationary work piece 6b, respectively, and a so-called collect chuck can be suitably used for this. 7 is a thrust receiver provided on the rotating chuck 2, and 8 is a thrust receiver of the stationary chuck 3 having a thrust bearing 9. The rotary side chuck 2 is directly rotationally driven by a pole number changing motor (not shown). For example, when the number of poles of the motor is 4, a rotation speed of 3000 rpm is obtained, and when the number of poles is 40, a rotation speed of 300 rpm is obtained. It is set to obtain the rotational speed. Of course, the number of poles and the rotation speed can be freely set as appropriate. Reference numeral 10 denotes a cutting tool for cutting away burrs that bulge out at the joints of the workpieces.

Next, to explain the operation, when the rotating chuck 2 is rotating at a set low speed, the rotating side work piece 6a and the stationary side work piece 6b are inserted into the rotating side chuck 2 and the stationary side chuck 3, respectively. Then, it is gripped by the gripping claws 4 and 5 (see point A shown in FIG. 5 and FIG. 1). When the gripping is completed, a pole number conversion command for the pole number conversion motor is issued (fifth
At the same time as point B shown in the figure), the fixed side chuck 3 is advanced toward the rotating side chuck 2, and after the rotational speed of the rotating side chuck 2 reaches the set high speed (time C shown in Figure 5), P1 Both workpieces 6a and 6b are brought into frictional contact under axial thrust, and the frictional heat generated at this time softens the joint between both workpieces 6a and 6b (frictional heat generation process) (see FIG. 2). After sufficient frictional heat generation is obtained, the command to change the number of poles is issued again (fifth
At point D in the figure), the rotational speed of the rotating chuck 2 now shifts to the set low speed. At this time, the rotational speed of the rotary side chuck 2 rapidly decreases due to the regenerative braking force acting on the pole number changing motor as the number of poles changes. Then, the rotation speed reached the set low speed (point E in Figure 5)
After this is detected by a rotational speed detector (for example, a rotary encoder) or the like, the gripping claw 5 of the stationary chuck 3 is released. Here, fixed side work piece 6
The end face of b is received by a thrust receiver 8 having a thrust bearing 9, and the rotating workpiece 6a continues to rotate, so the relative rotational speed of both workpieces 6a and 6b rapidly decreases. It will rotate as a unit. In this state, if the axial thrust P1 is maintained for a while, or if the axial thrust P2, which is even higher than the axial thrust P1, is added and maintained at appropriate times before and after the rotational chuck 2 shifts to low speed, friction welding is completed. . All that is left to do is to move back the stationary chuck 3 and release the gripping claws 4 of the rotating chuck 2 (see FIG. 4) before taking out the work piece 6. In addition, when attaching and detaching the work piece to and from the rotary side chuck 2, it can be done while the rotary side chuck 2 is rotating at a relatively low speed, so the operator can do it manually, or automatic loading/unloading can be carried out as appropriate. It is also possible to carry out mechanically with a device. Note that if it is necessary to remove the burr bulging at the joint of the work pieces 6 by cutting, the fixed side chuck 3 is released during the friction welding process described above so that the stationary side work piece 6b becomes the rotating side work piece. From the time when the cutting tool 10 begins to rotate almost integrally with the cutting tool 10, while maintaining the axial thrust for a while, the cutting tool 10
(See Figure 3).

As described above, according to the present invention, since the motor is always in a rotating state, the time required for rotation start-up when transitioning to high-speed rotation is shortened, and in particular, since the rotation start-up from a stopped state is not included, the load on the motor is reduced. The relative speed of a pair of workpieces becomes zero when it is necessary to cut away burrs that bulge at the joint of workpieces. Since the burr can be removed by cutting while the axial thrust is maintained for a while, the cycle time of the friction welding process can be significantly shortened, and the productivity can therefore be significantly improved. In addition, since a pole change motor is used as the drive source for the rotating chuck, there is no need for a clutch or braking device (brake), which simplifies the device configuration and reduces the cost of the device. It also has the effect of reducing.

In the above-mentioned embodiment, the fixed side chuck was configured to be able to move forward and backward toward the rotating side chuck. The same applies to the configuration.

[Brief explanation of the drawing]

The figure shows one embodiment of the present invention, and Figures 1 to 4 are explanatory diagrams showing the states in each step of friction welding, and Figure 5 shows the schematic relationship between rotational speed and axial thrust. It is a graph. 2...Rotating side chuck, 3...Stationing side chuck, 6...Work piece, 7, 8...Thrust receiver, 10...
Cutting tool.

Claims (1)

[Scope of Claims] 1. A step of gripping a work piece in a rotating chuck and a stationary chuck that rotate at a relatively low speed, respectively;
a friction heat generation process in which the rotating side chuck is rotated at a relatively high speed and then the pair of workpieces are brought into contact under axial thrust, and the vicinity of the joint surface is softened by the frictional heat generated at that time; At the final stage, the rotating side chuck is rapidly shifted to the relatively low speed rotation by regenerative braking of the pole number changing motor, and the stationary side chuck is released so that the stationary side work piece can rotate integrally with the rotating side work piece. a step of maintaining an axial thrust equal to or greater than the axial thrust; and then a step of relatively separating the rotating chuck and the stationary chuck and releasing the rotating chuck to take out the work piece. A friction welding method based on 2. The method according to claim 1, characterized in that, after releasing the stationary chuck, a step of cutting away a burr that bulges near the joint portion is performed in parallel during the step of sustaining the axial thrust. Method.