JPH11309526A - Blocking structure for end part of hollow tube, and method for machining the end part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent the one end part of the tube from being deformed by surely fixing and sealing a blind plug on the one end part of the hollow tube, and tightly receiving a large machining pressure received by the one tip part of the tube by the blind plug at the time of the form rolling of serration or thread and calking working. SOLUTION: To the one end part 2 of the hollow tube P, the blind plug 3 having an annular recessed groove 3a on its outer periphery is fitted, and on the inner peripheral surface of the one end part 2 of the hollow tube P, an annular prow 2t engaged integrally with the annular recessed groove 3a is formed by calking to the outer periphery. Also, on the outer peripheral surface of the one end part 2 of the hollow tube P, the serrations 2s and 2s or the thread are or is formed by rolling adjacently to the working portion 2k of the calking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for closing an end of a hollow pipe using a blind plug and a method for processing the end, and more particularly to a structure in which serrations or screws are formed on the outer peripheral surface of the end.

[0002]

2. Description of the Related Art A hollow pipe having an end closing structure as described above is used, for example, for a gear shift spindle of a motorcycle,
Conventionally used in brake shafts and the like.

[0003] When such a gear shift spindle or the like is manufactured from a hollow pipe, it is manufactured from a solid round bar (for example, after the required machining is performed on the outer periphery of the round bar, the round bar is deepened. Compared to the case of cutting a hole, the yield of the material is better, the processing steps are simpler, and the processing time is shortened.

[0004]

However, conventionally, in manufacturing the above-mentioned gear shift spindle or the like, the outer periphery and the end of the hollow pipe are subjected to necessary groove processing, screw processing, etc., and then the end is reamed. Since the blind plug was press-fitted, the number of processing steps as a whole increased, and strict precision control was required to firmly fix the blind plug and enhance its sealing, which increased the cost. And so on.

[0005] The present invention has been made in view of such circumstances, and can solve the above-described conventional problems.
An object of the present invention is to provide a structure for closing an end of a hollow pipe and a method for processing the end.

[0006]

In order to achieve the above object, an end closing structure for a hollow pipe according to the first aspect of the present invention comprises:
At one end of the hollow pipe, a blind plug having an annular groove on the outer periphery is fitted, and at the inner peripheral surface of the one end of the hollow pipe,
By the caulking process on the outer periphery, an annular projection integrally engaging with the annular groove is formed, and further, on the outer peripheral surface of the one end portion of the hollow pipe, a serration or a portion is formed adjacent to the processing portion of the caulking process. The screw is formed by rolling. According to this feature, the annular groove of the blind plug fitted to the inner peripheral surface of one end of the pipe and the annular projection formed by caulking on the inner peripheral surface are densely uneven over their entire circumference. The engagement surely prevents the blind plug from coming off, and also improves the sealing performance of the fitting portion between the blind plug and one end of the pipe. In addition, since the blind plug can stably receive a large processing pressure acting on one end of the pipe at the time of serration or thread rolling and caulking,
Deformation of one end of the pipe due to such processing is effectively avoided.

According to a second aspect of the present invention, there is provided a method of processing an end of a hollow pipe, wherein a blind plug having an annular concave groove is lightly press-fitted into one end of the hollow pipe, and a die is formed on at least one side of the caulking roller. Using a rolling die having a main body arranged adjacently, the outer periphery of the one end of the hollow pipe is caulked from above the annular groove with the caulking roller, and the inner peripheral surface of the one end is integrally engaged with the annular groove. Forming a serrated or threaded screw with the die body on the outer peripheral surface of one end portion thereof. According to this feature, in addition to the function and effect of the feature of the first aspect of the present invention, when the blind plug is assembled, the blind plug is fitted into one end of the pipe by light press-fitting. Strict dimensional control is not required,
In addition, even with the use of such light press fitting, the blind plug can be securely fixed to one end of the pipe by subsequent caulking. Furthermore, since the rolling and forming of the serration or the screw on one end of the pipe and the crimping can be simultaneously performed by the rolling dies with the caulking rollers, the number of processing steps is reduced and the process is simplified.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below based on embodiments of the present invention illustrated in the accompanying drawings.

FIG. 1 is an overall front view of a gear shift spindle for a motorcycle according to an embodiment of the present invention, and an enlarged longitudinal sectional view of one end thereof. FIG. 2 is a blind plug and a gear shift before assembly processing. Fig. 3 shows the main part of the spindle.
FIG. 4 is an essential part cross-sectional view showing a state in which a blind plug is lightly pressed into one end of a gear shift spindle, and FIG. 4 is an essential part longitudinal sectional view showing a process of simultaneously performing serration and caulking on one end of the gear shift spindle, and FIG. It is an arrow view.

In this embodiment, a gear shift spindle for a motorcycle is shown as a hollow pipe P made of metal. In FIG. 1, an annular locking groove 1 for locking a circlip (not shown) is cut at an appropriate position on the outer periphery of a hollow pipe P, and one end 2 of the pipe P is drawn to form a pipe main body. Are also formed with a small diameter.

A solid metal blind plug 3 for closing the open end of the one end 2 is fitted on the inner periphery of the pipe one end 2, and the blind plug 3 is formed in a round bar shape in the illustrated example. An annular concave groove 3a having an arc-shaped cross section is formed in the outer periphery at an intermediate portion in the longitudinal direction. On the inner peripheral surface of the one end portion 2 of the pipe, an annular projection 2t integrally engaging with the annular groove 3a is formed in an arc shape in cross section by caulking the outer periphery of the one end portion 2, Furthermore, on the outer peripheral surface of the one end portion 2,
A serration 2 is formed adjacent to the machined portion 2k of the caulking process and at least one side in the axial direction (both sides in the illustrated example).
s and 2s are roll formed around the entire circumference.

According to the above structure, the annular projection 2t formed by caulking on the inner peripheral surface of the one end portion 2 of the pipe and the annular concave groove 3a of the blind plug 3 fitted on the inner peripheral surface are formed by the two. Since the concave-convex engagement can be made densely over the entire circumference, the blind plug 3
Of the fitting part between the outer circumference of the blind plug 3 and the inner circumference of the one end 2 is also improved. Further, since a large working pressure which the pipe end 2 receives during the rolling forming and crimping of the serration 2s can be stably received by the blind plug 3, it is extremely effective in preventing the deformation of the pipe end 2.

Next, a procedure for fixing the blind plug 3 to the one end 2 of the hollow pipe P and forming the serrations 2s will be described with reference to FIGS.

First, as shown in FIG. 2, a blind plug 3 is manufactured.
An annular groove 3a is cut on its outer peripheral surface. on the other hand,
The hollow pipe P is formed by cutting a pipe material to an appropriate length and drawing one end 2 of the hollow pipe P into a smaller diameter than the pipe body. In this case, the inner diameter of the one end portion 2 and the outer diameter of the blind plug 3 are set to a tight allowance so that both can be lightly pressed in the next step. Further, a groove 1 for locking the circlip is cut in an appropriate position on the outer periphery of the hollow pipe P.

Next, as shown in FIG. 3, the blind plug 3 is lightly pressed into the inner periphery of the one end 2 of the hollow pipe P, and the blind plug 3 is temporarily fixed.

Thereafter, as shown in FIG. 4, the disk-shaped die bodies Da, Da are also provided on both sides of the disk-shaped caulking roller Dr.
A pair of rolling dies D is prepared by fixing Da adjacently on the same axis, and the two rolling dies D are arranged so as to sandwich one end 2 of the hollow pipe P therebetween, and are not shown. The actuator is slowly driven to rotate in the opposite direction to each other, and at this time, the one end 2 of the hollow pipe P is strongly pressed by its two rolling dies D toward the center axis. In this case, both the rolling dies D are axially positioned with respect to the dies D and the pipe end 2 such that the caulking roller Dr corresponds to the annular groove 3a of the blind plug 3.

According to the pressing and rotation of the two rolling dies D, the outer periphery of the one end 2 of the hollow pipe P is caulked from above the annular groove 3a by the caulking roller Dr of the dies D. An annular projection 2t integrally formed with the annular groove 3a is formed on the inner peripheral surface of the one end portion 2, and at the same time, each die body Da, Da of the rolling die D is formed on the outer peripheral surface of the one end portion 2. Thus, the serrations 2s are roll formed.

According to such a procedure, when the blind plug 3 is assembled, the blind plug 3 is fitted into the one end 2 of the pipe by light press-fitting. Strict dimensional control becomes unnecessary, and even with the use of such light press fitting, the blind plug 3 can be securely fixed to the pipe end 2 by the subsequent caulking process. Furthermore, since the rolling forming of the serrations 2s on the pipe end 2 and the crimping can be simultaneously performed by the rolling dies D with the caulking rollers, the number of processing steps is reduced, and the process is simplified.

Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments, and various embodiments are possible within the scope of the present invention. For example, in the above-described embodiment, one end 2 of the hollow pipe P to which the blind plug 3 is attached is drawn in advance to have a smaller diameter than the pipe main body. A pipe formed to have the same diameter or a large diameter as the pipe body may be used.
Further, in the above embodiment, the die bodies Da,
Although the case where the serration 2s is roll-formed by Da is shown, in the present invention, a screw may be roll-formed instead of the serration.

[0020]

As described above, according to the first and second aspects of the invention, an annular concave groove of a blind plug fitted to the inner peripheral surface of one end of the hollow pipe, and the inner peripheral surface formed by caulking. Can be tightly engaged with the annular projections over their entire circumference, so that the blind plug can be securely fixed to one end of the pipe, and the blind plug can be pulled out due to vibration or the like. Can be effectively avoided, and the sealing performance of the fitting portion between the blind plug and one end of the pipe can be improved. In addition, a large processing pressure received at the end of the pipe during serration or screw rolling and caulking can be firmly received by the blind plug fitted to the end of the pipe, thereby preventing deformation of the end of the pipe. It is effective for

According to the second aspect of the present invention, when the blind plug is assembled, the blind plug is fitted into one end of the pipe by light press-fitting, so that strict dimensional control of the fitting portion becomes unnecessary. In addition, even by adopting such a light press-fitting, the blind plug can be securely fixed to one end of the pipe by the subsequent crimping process. Furthermore, since the rolling forming of the serration or the screw on one end of the pipe and the crimping can be simultaneously performed by the rolling dies with the caulking rollers, the number of processing steps can be reduced and the process can be simplified. As a result, it is possible to greatly contribute to improvement of processing efficiency and cost reduction as a whole.

[Brief description of the drawings]

FIG. 1 is an overall front view of a gear shift spindle for a motorcycle according to one embodiment of the present invention, and an enlarged longitudinal sectional view of one end thereof.

FIG. 2 is a view of a main part of a blind plug and a gear shift spindle before assembling processing.

FIG. 3 is a sectional view of a main part showing a state in which a blind plug is lightly pressed into one end of a gear shift spindle.

FIG. 4 is a longitudinal sectional view of a main part showing a step of simultaneously performing serration processing and crimping processing on one end of a gear shift spindle, and a view on arrow A thereof.

[Explanation of symbols]

 P ···· Hollow pipe 2 ···· One end 2k ··· Caulking portion 2s ··· Serration 2t ··· Annular projection 3 ····· blind plug 3a ··· Annular groove D · · · · rolling die Da · · · · die body Dr · · · · caulking roller

Claims (2)

[Claims] At one end (2) of a hollow pipe (P),
A blind plug (3) having an annular concave groove (3a) on its outer periphery is fitted, and the inner peripheral surface of the one end (2) of the hollow pipe (P) is formed by caulking the outer periphery thereof. Groove (3
an annular projection (2t) integrally formed with a) is formed,
Further, serrations (2s, 2s) or screws are formed on the outer peripheral surface of the one end portion (2) of the hollow pipe (P) adjacent to the processing portion (2k) of the crimping process. The hollow pipe end closure structure. 2. A step of lightly press-fitting a blind plug (3) having an annular groove (3a) on an outer periphery into one end (2) of a hollow pipe (P), and a die at least on one side of a caulking roller (Dr). A rolling die (D) having a main body (Da, Da) arranged adjacent thereto is used, and the annular groove (3a) is formed by the caulking roller (Dr).
An outer periphery of the one end (2) of the hollow pipe (P) is crimped from above, and an annular projection (2t) integrally engaged with the annular groove (3a) is formed on an inner peripheral surface of the one end (2). And forming a serration (2s, 2s) or a screw with the die body (Da, Da) on the outer peripheral surface at one end (2) of the hollow pipe. Edge processing method.