JP2001349313A - Male screw and rolling method for it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a male screw capable of being tightened with comparatively small force, providing very large contact resistance with a female screw and being favorably prevented from being loosened by vibration. SOLUTION: In this male screw having a screw part 31, the screw part 31 is larger in effective diameter dimension d1 at one end than the effective diameter dimension d2 at the other end. At the part having the smaller effective diameter dimension d2, the male screw can be easily tightened wit the comparatively small force, and at the part having the larger effective diameter dimension d1, the contact resistance with the female screw can be greatly enlarged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a male screw such as a hexagon bolt and a hexagon socket head bolt, and a method for rolling the male screw.

[0002]

2. Description of the Related Art A male screw such as a hexagon bolt has a threaded portion having a thread and a hexagonal head provided at one end of the threaded portion, and the threaded portion has an effective diameter over its entire length. The dimensions are equal.

[0003] In addition, a method of rolling a male screw such as a hexagon bolt uses a pair of rotatable round dies having a threaded portion, and rotates one of the dies while rotating the other of the dies. The thread portion rolls the material of the external thread interposed between the dies to form a thread on the surface of the material. Each of the dies has the thread crests and roots of the threads equal over the entire length of the threads.

[0004]

However, in the conventional rolling method, a pair of dies in which the crests and roots of the thread portion of the thread portion are equal over the entire length of the thread portion are used. Since the effective thread size of the thread portion of the male screw is equal over the entire length, when the rolled male screw is screwed to the female screw to fix and connect mechanical parts and equipment, mechanical parts,
The male screw loosens very little by vibration or the like applied to the device and the like, and the fixing and connection by the male screw are released. To solve this problem, a spring washer is used to prevent the screws from loosening, but it is still not enough, and the number of parts increases and the assemblability deteriorates. It had been.

The present invention has been made in view of the above-mentioned circumstances, and the effective diameter is reduced by making the effective diameter at one end of the threaded portion larger than the effective diameter at the other end. The part can be easily tightened with a relatively small force, and the part with a large effective diameter dimension can greatly increase the contact resistance with the internal thread, preventing the loosening of the male thread due to vibration etc. The purpose of the present invention is to provide a male screw that can be used.

It is another object of the present invention to provide a male screw having a structure in which the outer diameter of the screw portion is the same over the entire length, thereby preventing a decrease in strength at a portion where the effective diameter changes.

[0007] Further, by rolling using a pair of dies in which the top of the thread at one end of the thread is lower than the top of the thread at the other end, the effective diameter of the male screw can be reduced by a single rolling process. An object of the present invention is to provide a rolling method capable of rolling a small portion and a portion having a large effective diameter.

[0008] A material of a male thread having an outer diameter dimension at one end side larger than an outer diameter dimension at the other end side is used, and one end side of the die is rolled at a portion where the outer diameter dimension of the material is large. By rolling the portion having a small outer diameter of the die at the other end side of the die, the outer diameter of the thread portion of the male screw can be made equal, and the strength is reduced at the portion where the effective diameter changes. It is an object of the present invention to provide a rolling method capable of improving the durability of a male screw.

[0009]

According to a first aspect of the present invention, there is provided a male screw wherein the effective diameter of the thread portion at one end is larger than the effective diameter at the other end.

According to the first aspect of the present invention, when the screw is tightened into a screw because the hole is drilled corresponding to a portion having a small effective diameter, the other end of the screw having a small effective diameter is tightened with a relatively small force. In addition, a relatively large tightening force is required on one end side where the effective diameter of the screw portion is large, but the contact resistance with the female screw can be very large, so that the The male screw can be easily tightened with a relatively small force by tightening the female screw from the other end with a small effective diameter, and when the unthreaded length of the screw becomes short, the screw becomes effective. By tightening one end having a large diameter, the contact resistance with the female screw can be made extremely large, and the loosening of the male screw due to vibration or the like can be prevented well.

A male screw according to a second aspect of the present invention is characterized in that the outer diameter of the screw portion is equal over the entire length.

In the second invention, since the outer diameter of the portion having a small effective diameter is equal to the outer diameter of the portion having a large effective diameter, a decrease in strength at the portion where the effective diameter changes can be eliminated. The durability of the screw can be increased.

According to a third aspect of the present invention, there is provided a method for rolling a screw by rotating or moving at least one of a pair of dies having a threaded portion, wherein each of the dies is provided with a thread at one end of the threaded portion. It is characterized in that a thread having a crest that is lower than the crest of the thread on the other end side is used, and rolling is performed with a male screw material interposed between the pair of dies.

In the third aspect of the present invention, since the heights of the crests of the pair of dies are different, a portion having a small effective diameter and a portion having a large effective diameter are formed by a single rolling process. The thread can be rolled, and a male screw having a different effective diameter of the thread portion can be rolled without increasing the number of rolling steps as compared with a conventional rolling method.

In the rolling method according to a fourth aspect of the present invention, the material has an outer diameter at one end larger than an outer diameter at the other end. One end is rolled, and the other end of the die is rolled at a portion where the outer diameter of the material is small.

According to the fourth aspect of the present invention, since the outer diameter of the material at the portion where the effective diameter of the thread portion becomes larger is larger than the outer diameter of the material at the portion where the effective diameter becomes smaller, When a screw is rolled using a die in which the crest of one end side thread is lower than the crest of the other end side thread, the outer diameter of the thread portion of the external thread can be equalized, and the effective diameter The strength can be prevented from being reduced at the part where the thread changes, and the durability of the male screw can be increased.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. Embodiment 1 FIG. 1 is a schematic view of an external thread rolling device.

The rolling device shown in FIG.
1 and a pair of circular dies 1, 1 spaced apart in the radial direction, and a material receiving table 2 arranged between the dies 1, 1
This is a round die type rolling device provided with: Dice 1,1
Are supported by a stationary member so that they can rotate in conjunction with each other, and one of the dies 1 and 1 can be moved toward the other die.

FIG. 2 is an enlarged sectional view of a portion to be rolled, and FIG. 3 is an enlarged sectional view of a thread portion of a die. The thread portion 11 of the dies 1 and 1 has the same pitch P and the same thread angle θ from one end to the other end.

The dies 1, 1 are each divided from the middle between one end and the other end in a direction perpendicular to the axis. Thread 11 of the divided first divided body 1a and second divided body 1b
a, 11b are continuous at the above-mentioned pitch P and the thread angle θ, and the effective diameter D1 of the threaded portion 11 of the first divided body 1a.
Is smaller than the effective diameter D2 of the screw portion 11 of the second divided body 1b, and the thread 11a of the first divided body 1a
Is smaller than the top a of the thread 11b of the second divided body 1b, and the bottom b of the thread 11a of the first divided body 1a is the bottom b of the thread 11b of the second divided body 1b. The height H of the thread 11a of the first divided body 1a is lower than the height H of the thread 11b of the second divided body 1b. The length of the first divided body 1a in the axial direction is set to about 1/4 of the axial length of the dies 1 and 1, but the length is not particularly limited.

The threaded portion 11 of the first divided body 1a has a larger amount of chamfer H1 at the top of the screw than the amount of chamfered H2 at the top of the threaded portion of the second divided body 1b. The threaded portion 11 of the divided body 1a is formed by making the chamfer amount H3 of the valley between the adjacent screw threads larger than the chamfered amount H4 of the valley of the screw portion 11 in the second divided body 1b. The effective diameter D1 of the threaded portion 11 is smaller than the effective diameter D2 of the threaded portion 11 of the second divided body 1b, and the top a of the thread 11a and the height H of the thread 11a are set to 1
The top a of 1b and the height H of the thread 11b are each lower than the root H of the thread 11a, and the root b of the thread 11a is made shallower than the root b of the thread 11b.

The first divided body 1a and the second divided body 1b thus divided are integrally connected by a connecting means such as a bolt.

FIG. 4 is an enlarged sectional view of the rolled state, and FIG. 5 is a front view of the rolled male screw. When a screw is rolled using the die configured as described above, the screw material 3a is received in the material receiving table 2 between the dies 1, 1 rotatably supported by the stationary member. By rotating one pair of dies 1, 1 while moving one die toward the other die (moving in the radial direction), the dies 1, 1
1 is pressed against the surface of the material 3a, and the surface of the material 3a is plastically deformed to form a screw portion 31 corresponding to the shape of the screw portion 11. The male screw 3 having 31 can be rolled by one rolling process.

FIG. 6 is an enlarged sectional view of a part of the rolled male screw. The thread portion 31 of the rolled external thread 3 has the same pitch P and the same thread angle θ from one end to the other end, and further has an effective diameter dimension d at one end side which is the head side.
1 becomes larger than the effective diameter dimension d2 on the other end side.

The threaded portion 31 of the male screw 3 has a chamfered amount h1 at one end of the thread crest and a chamfered amount h at the other end.
2, the effective diameter dimension d1 at one end is reduced to the effective diameter dimension d2 at the other end by making the chamfer amount h3 of the valley at one end smaller than the chamfer amount h4 of the valley at the other end. It is larger than. The length of the effective diameter dimension d1 in the axial direction is about 約 of the axial length of the screw portion 31, but the length is not particularly limited. In addition, the effective diameter dimension d
The dimensional difference between 1 and the effective diameter d2 is, for example, about 0.050 to 0.150 when the nominal diameter of the screw is 12, but the dimensional difference is not particularly limited.

The male thread rolled in this way is drilled corresponding to the effective diameter dimension d2 of the other end which is smaller than the effective diameter dimension d1 of the one end, and is tightened into the screw. It is used for fixing or connecting mechanical parts, devices and the like. Effective diameter dimension d of screw part 31
On the other end side where 2 is small, it can be tightened with a relatively small force, similarly to a conventional screw. Then, when the untightened length of the screw portion 31 is shortened due to the tightening, the contact resistance with the female screw is greatly increased by tightening the one end side where the effective diameter dimension d1 of the screw portion 31 is large. That is, the effective diameter of the internal thread is d2 described above. Since the external thread of the effective diameter d1 is screwed into the internal thread of the effective diameter d2, the contact resistance with the internal thread is extremely low. And the loosening of the male screw due to vibration or the like can be favorably prevented.

Embodiment 2 FIG. 7 is an enlarged sectional view of a portion to be rolled. Embodiment 2
The method of rolling the male screw is such that the material 3a of the male screw 3 is such that the outer diameter of one end is larger than the outer diameter of the other end,
The first divided bodies 1a, 1a of the dies 1, 1 roll a portion 3b of the material 3a having a large outer diameter, and the material 3a
The part 3c having a small outer diameter of the second divided body 1b, 1
b is formed by rolling.

FIG. 8 is an enlarged sectional view of the thread portion of the die. In the second embodiment, the screw portion 1 of the first divided body 1a
1 is such that the chamfer amount H1 of the screw crest is larger than the chamfer amount H2 of the screw crest of the screw portion 11 in the second divided body 1b,
Further, the threaded portion 11 of the first divided body 1a has the first chamfered amount H3 between the adjacent screw threads equal to the chamfered amount H4 of the threaded portion 11 of the second divided body 1b.
The effective diameter D1 of the threaded portion 11 of the divided body 1a is smaller than the effective diameter D2 of the threaded portion 11 of the second divided body 1b. Are lower than the height a of the thread 11b and the height H of the thread 11b, respectively, and the bottom b of the thread 11a is
The depth is equal to the valley bottom b of 1b. Material 3a
The dimensional difference between the large diameter portion 3b and the small diameter portion 3c of the first divided body 1a depends on the chamfer amount H1 of the thread crest of the first divided body 1a and the second diameter.
The dimension corresponds to the difference from the chamfer amount H2 of the thread crest of the divided body 1b.

FIG. 9 is an enlarged sectional view of a rolled state, and FIG.
Is a front view of the rolled male screw, and FIG. 11 is a cross-sectional view in which a part of the male screw is enlarged. In the second embodiment, the material has a dimension corresponding to the difference between the chamfered amount H1 of the thread crest of the first divided bodies 1a and 1a and the chamfered amount H2 of the thread crest of the second divided body 1b. Since the first divided body 1a, 1a rolls a portion 3b having a large outer diameter of 3a and the second divided body 1b, 1b rolls a part 3c having a small outer diameter of the raw material 3a, The outer diameter dimension of the screw portion 31 can be made equal.

Since other configurations and operations are the same as those of the first embodiment, the same components are denoted by the same reference numerals.
The detailed description and the description of the operation will be omitted.

In the first and second embodiments described above,
Although the method of rolling a screw using a round die-type rolling device having a pair of round dies has been described, in addition, the rolling method of the present invention employs a method of rolling a male screw between a pair of flat dies. With a material interposed, a flat die rolling device that rolls screws by moving one flat die, or a male screw material interposed between an arc segment die and a round die, and a round die May be used, and a planetary rolling device for rolling a screw may be used. Also in this case, the pair of dies is divided as in the first and second embodiments, and at least the top a of the thread 11a of the first divided body 1a is lower than the top a of the thread 11b of the second divided body 1b. An external thread in which the effective diameter dimension d1 on one end side which is the head side is larger than the effective diameter dimension d2 on the other end side is rolled.

[0032]

According to the first aspect of the present invention, when a male screw is tightened into a screw because it is drilled corresponding to a portion having a small effective diameter, the male screw is screwed into the female screw from the other end having a small effective diameter. It can be easily tightened with relatively small force,
In addition, when the unthreaded length of the thread is shortened, the contact resistance with the female thread can be extremely increased by tightening the one end side where the effective diameter of the thread is large. Can be properly prevented from relaxing.

According to the second aspect, it is possible to prevent the strength from being reduced at the portion where the effective diameter dimension changes, and to increase the durability of the male screw.

According to the third invention, a portion having a small effective diameter and a portion having a large effective diameter can be rolled by a single rolling process. Male screws having different effective diameters of the threaded portions can be rolled without increasing.

According to the fourth aspect, when a screw is rolled using a die in which the top of the thread at one end of the thread is lower than the top of the thread at the other end, the outside of the thread of the external thread is used. The diameters can be equalized, the strength can be prevented from being reduced at the portion where the effective diameter changes, and the durability of the male screw can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic view of a thread rolling device for male threads according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a portion for rolling a male screw according to the present invention.

FIG. 3 is an enlarged sectional view of a thread portion of a die for rolling a male thread according to the present invention.

FIG. 4 is an enlarged sectional view of a state in which the male thread according to the present invention is rolled.

FIG. 5 is a front view of the male screw according to the present invention.

FIG. 6 is an enlarged sectional view of a part of the male screw according to the present invention.

FIG. 7 is an enlarged cross-sectional view of a portion where the male screw according to the present invention is rolled.

FIG. 8 is an enlarged sectional view of a thread portion of a die for rolling a male thread according to the present invention.

FIG. 9 is an enlarged cross-sectional view of a state where the external thread according to the present invention is rolled.

FIG. 10 is a front view of the male screw according to the present invention.

FIG. 11 is an enlarged sectional view of a part of the male screw according to the present invention.

[Description of Signs] 1 Die 11 Screw part a Thread crest 3 Male thread d1, d2 Effective diameter

Claims (4)

[Claims] 1. A male screw, wherein the effective diameter of the thread portion at one end is larger than the effective diameter at the other end. 2. The male screw according to claim 1, wherein the outer diameter of the screw portion is equal over the entire length. 3. A method of rolling a screw by rotating or moving at least one of a pair of dies having a threaded portion, wherein each of the dies has a top end of a thread at one end of the threaded portion and a thread at the other end. A method for rolling a male screw, comprising using a material lower than the top of a mountain and rolling a male screw material between the pair of dies. 4. A material having an outer diameter at one end larger than an outer diameter at the other end is used, and a portion having a larger outer diameter at the one end is rolled by one end of the die. 4. The method of rolling an external thread according to claim 3, wherein the other end of the die rolls a portion having a small outer diameter.