JPS61189838A - Closed working method of pipe end part - Google Patents

Abstract

PURPOSE:To work with a simple equipment and to reduce the equipment cost and die cost by performing a continuous working of the upper end of the pipe inserted into a die, using a large diameter punch and the small diameter punch which is slidable freely in the inner part thereof. CONSTITUTION:A pipe 1 is inserted into the insert hole 12 of the pipe so that the upper end 1a thereof can project into the large diameter aperture part 11 by the prescribed length. A large diameter punch 21 and small diameter punch 22 are moved down by unifying the lower ends 21a, 22a thereof with lining on the same plane and inserted into the large diameter hole part 11. Both punches 21, 22 are further moved down and the upper end 1a of the pipe 1 is gradually upsetted with being plastically deformed. When both punches 21, 22 are descended until the lower end of the large diameter hole part 11, the upper end 1a of the pipe 1 becomes in the state of half blocking the inner diameter at the upper end part of the part inserted into the insert hole 12. The small diameter punch 22 only is descended then and inserted into the pipe insert hole 12. The upper end 1a of the pipe 1 pushed by the lower end face 22a of the small diameter punch 22 is further deformed plastically and the pipe upper end is fully closed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for closing the end of a pipe used in manufacturing hollow valve stems for engines.

(Prior art) Engine intake and exhaust valves are required to be lightweight in order to minimize the influence of inertia of the valves when the engine rotates at high speeds, and for this reason, the use of hollow valve stems has also been considered. ing. When manufacturing a hollow valve stem, it is very difficult to manufacture a hollow stem from the beginning, so a method is often used in which the end of the pipe is closed off using a pipe.

As a method of closing the end of the vibrator, for example, Japanese Patent Application Laid-open No. 5
As disclosed in Japanese Patent No. 9-125220, a core metal is inserted into the pipe with a predetermined length remaining at the tip end of the pipe, and the metal core is gripped with a chuck and rotated at high speed, and the tip end is cut into a processing tool. There is a method of closing the end of the pipe in accordance with the shape of the core metal by pressing it onto the core metal and using the frictional heat generated at this time.

However, this method requires a core metal that matches the inner diameter of the pipe and a device that rotates the pipe with the core inserted at high speed, making the equipment for performing the closing process relatively complicated and expensive. Since it is necessary to roughly insert the core metal into the pipe, there is a problem that only one end of the pipe can be closed, but both ends cannot be closed.

(Object of the Invention) The present invention has been made in view of such problems, and an object of the present invention is to provide a method for closing both ends of a pipe using a relatively simple device. It is.

(Structure of the Invention) The method for closing the end of a vibrator of the present invention includes a linearly extending pipe fitting hole and a large diameter hole portion having a larger diameter than the pipe fitting hole formed near the frontage of one end of the pipe fitting hole. A processing method using a die, a cylindrical large-diameter punch that can fit into a large-diameter hole, and a cylindrical small-diameter punch that can slide freely within the large-diameter punch and can fit into a pipe insertion hole. A pipe, which is a workpiece, is inserted into the pipe fitting hole so that one end thereof protrudes a predetermined length into the large diameter hole, and the large diameter punch and the small diameter punch are fitted into the large diameter hole, The pipe is characterized in that the upper end of the pipe protruding into the large-diameter hole is crushed, and then only the small-diameter punch is moved and fitted into the pipe insertion hole to close one end of the pipe.

(Example) Preferred examples of the processing method of the present invention will be described below with reference to the drawings.

1 to 5 are cross-sectional views showing the method of closing the end of a pipe according to the method of the present invention in the order of steps. This processing is performed using a die 10 and a punch 20.
The die 10 has a pipe fitting hole 12 extending vertically with a diameter large enough to fit the pipe 1 as a workpiece, and a hole larger than the inner diameter of the pipe fitting hole 12 near the upper end opening of the pipe fitting hole 12. It has a large diameter hole 81111 extending above and below the inner diameter, and has a large diameter hole 11 and a pipe fitting hole 12.
and are smoothly connected to each other via the tapered portion 13. On the other hand, the punch 20 serving as a mating tool for the die 10 includes a cylindrical large-diameter punch 21 that can be freely fitted into the large-diameter hole 11, and a small-diameter punch 2 that can freely move around the inner diameter part 21a of the large-diameter punch 21.
It consists of 2.

(1) To perform the plugging process, first, as shown in FIG. 1, the pipe 1 is inserted into the pipe insertion hole 12 so that the upper part 1a protrudes into the large diameter hole 11 by a predetermined length. Next, the large-diameter punch 21 and the small-diameter punch 22 are moved downward together with the lower ends 21a and 22a of both punches aligned on the same plane, and fitted into the large-diameter hole 11.

Both punches 21 and 22 are moved further down while still being integrated, and the upper end 1a of the pipe 1 is gradually crushed while being plastically deformed within the large diameter hole 11, as shown in FIGS. 2 to 4. At this time, the upper end 1a of the pipe 1 is crushed and its inner diameter portion is pushed inward.

As shown in FIG. 4, both punches 21 and 22 are inserted into the large diameter hole
When the pipe 1 is lowered almost to the lower end, the upper end 1a of the pipe 1
is plastically deformed and the inner diameter of the upper end portion of the portion inserted into the pipe insertion hole 12 is partially closed.

Next, from this state, as shown in FIG. 5, only the small diameter punch 22 is moved downward while the large diameter punch 21 is held as it is, and the small diameter punch 22 is inserted into the pipe insertion hole 12. At this time, the upper part of the pipe 1 @1a pushed by the lower end surface 22a of the small diameter punch 22 is further plastically deformed and completely closes the upper end of the pipe, so if this pipe 1 is taken out, a pipe with one end closed can be obtained. can. moreover,
If the other end is also to be closed, the pipe may be turned upside down and inserted into the die 10, and the same operation as above may be performed.

With the above method, only one die 10 is required, and the punch 20 makes the forming process a continuous process, resulting in high productivity.

(Effects of the Invention) According to the processing method of the present invention, the upper end of the pipe inserted into the die can be continuously processed using a large-diameter punch and a small-diameter punch that can freely slide inside the die, increasing productivity. is high. Furthermore, only one die is required and the movement of the punch relative to the die is only up and down movement, so the processing equipment is relatively simple and equipment costs and mold costs can be reduced.

Furthermore, both ends of the pipe can be closed without any problem.

[Brief explanation of the drawing]

1 to 5 are cross-sectional views sequentially showing the steps of closing the end of a pipe according to the method of the present invention. 1...Pipe 10...Dice 11...
・Pipe insertion hole 12...Large diameter hole 21...Large diameter punch 22...Small diameter punch Figure 4 Figure 5

Claims (1)

[Scope of Claims] It has a pipe fitting hole extending linearly into which a pipe as a workpiece is fitted, and a hole portion with a larger diameter than the pipe fitting hole near one end opening of the pipe fitting hole. The pipe is inserted into the pipe fitting hole such that one end of the pipe protrudes into the large diameter hole by a predetermined length, and a cylindrical large diameter that can be fitted into the large diameter hole is inserted into the die. A punch and a cylindrical small-diameter punch that is slidable in the punch axial direction within the large-diameter punch and fitable in the pipe insertion hole are fitted into the large-diameter hole, and the punch is inserted into the large-diameter hole. In the pipe, one end of the pipe protruding into the large-diameter hole is crushed, and then only the small-diameter punch is moved to fit into the pipe insertion hole, thereby closing the one end of the pipe. End closure processing method.