JPH07139536A - Fastening member and manufacture thereof - Google Patents

Abstract

PURPOSE:To surely prevent looseness of fastening members without using a part such as washer. CONSTITUTION:In thread members provided with a first thread member 1 and a second thread member 2, the first thread member 1 is formed with compressive contact parts 25 on the extreme end side, compressive contact parts 26 on the root side, and recessed parts 27. When the first thread member 1 and the second thread member 2 are threadedly engaged with each other, either of the compressive contact parts 25 on the extreme end side or the compressive contact parts 26 on the root side 26 are elastically deformed in the direction in parallel with the axis, this elastic deformation is converted to the other compressive contact part through the recessed part 27, and hence the two thread members are fastened while respectively receiving strong resisting force on both compressive contact parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fastening member having a male screw and a female screw and a technique for manufacturing the same, and more particularly to a fastening member having an improved fastening force between the male screw and the female screw and a technique for manufacturing the same. .

[0002]

2. Description of the Related Art A screw member composed of a bolt and a nut is used to fasten a plurality of fastened parts to each other.
In order to prevent loosening of the bolt and nut, it is usual to additionally use parts such as spring washers.

In order to prevent loosening of the bolt and the nut without using such an additional part, the thread of the bolt is formed with a slit extending in the radial direction from the tip of the thread. However, for example
It is described in Japanese Patent No. 6686.

The screw member described in this publication is such that the screw thread of one screw member is divided into two parts in the axial direction through a slit, and the side surface of the screw thread is radially centered. The part is pressed against the side surface of the other screw member.

[0005]

By the way, the inventor of the present invention has studied a technique in which two screw members are screw-coupled to each other with a strong fastening force. The following is the technique examined by the present inventor, and the outline thereof is as follows.

That is, when a slit is formed on the male thread side, that is, on the thread side of the bolt side, in order to prevent loosening of the bolt and the nut from each other, a strong pressure contact with the nut is made at a portion as far as possible from the shaft center of the bolt. It is considered that when the force is applied, a larger resistance force is generated and the tightening force can be secured even for a large torque.

Further, of the side surfaces of the thread of the bolt, the tip end side and the root side of the thread are brought into pressure contact with the thread of the nut, so that both parts mutually press the side surfaces of the thread of the nut. It is believed that they can influence each other and a good balance of tightening forces can be achieved.

An object of the present invention is to provide a fastening member which is made up of a male screw and a female screw which can strengthen the fastening force and which can fasten each other with a strong fastening force.

Another object of the present invention is to provide a method of manufacturing a fastening member which can efficiently manufacture a self-locking screw member.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0011]

Of the inventions disclosed in the present application, a representative one will be briefly described below.
It is as follows.

That is, the fastening member has a first screw member having a tip portion and a side surface and having a first screw thread formed by spirally projecting from the screw body portion, and a screw body having a tip portion and a side surface. A second screw member that has a second screw thread that is formed to spirally project from the portion and that is screwed to the first screw member by relative rotation about an axis. The first screw thread is formed with a slit extending in the radial direction from the tip portion of the first screw thread, and the tip end portion of the first screw thread is in pressure contact with the side surface of the second screw thread. And a second portion is formed on the side surface of the first screw thread.
A root-side pressure contact portion that pressure-contacts the side surface of the screw thread is formed. Then, when the first screw member and the second screw member are screwed together, elastic deformation of one of the tip side pressure contact portion and the root side pressure contact portion, which is parallel to the axial center, is caused by the other second deformation. The recess for converting the pressure contact force toward the thread is the second
It is formed on the side surface of the screw thread so as to be located between the tip side pressure contact portion and the root side pressure contact portion.

Further, there is provided a rough material forming step for forming a screw rough material having a double thread including a slit thread groove corresponding to a slit and a product thread groove corresponding to a thread groove between threads, and a flat material rolling step. A single-thread screw forming process in which the interval between the thread grooves for slits is narrowed using a forming die and the interval between the screw grooves for products is widened to form a single-thread screw, and the thread of the single-thread screw is formed using a flat rolling die. And forming a recess on the side surface of the product, and deepening the product thread groove of the single-threaded screw to form a root-side press contact portion and a recess and form a screw.

[0014]

When the first screw member and the second screw member are screwed together, one of the tip side pressure contact portion and the root side pressure contact portion formed on the first screw member is oriented along the axial center of the screw member. Elastically deforms, and the elastic deformation is converted into the other elastic deformation through the concave portion, so that both pressure contact portions are strongly pressed against the second screw member. As a result, the fastening force becomes stronger, and the loosening of the screw member in a screwed state is prevented.

On the other hand, after molding a thread rough material having a double thread consisting of a thread groove for slit and a thread groove for product, the width of the thread groove for slit is narrowed to form a single thread, and further in the finishing step. By molding the final shape of the one screw member, the first screw member can be manufactured by a simple process.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments of the present invention shown in the drawings.

(Embodiment 1) FIG. 1 is a sectional view showing a state in which a normal bolt 1 and a nut 2 are screwed together. The bolt 1 serves as a first screw member and a nut 2 serving as a second screw member. By rotating the bolt 1 relative to the shaft center 3 relative to each other, these can be screwed to each other or the screw connection can be released. The bolt 1 is formed of a rod-shaped main body 4 having a circular cross section and a screw thread 5 formed integrally with the main body 4 and protruding in a spiral shape outward from the main body 4, and the nut 2 is formed of an annular main body 6. And a screw thread which is integrally formed with this and which is formed so as to spirally project inward from the inner surface of the main body portion toward the shaft center 3.

2 (a) and 2 (b) are enlarged sectional views showing a part of the fastening member according to the embodiment of the present invention.
(A) shows the bolt 1 before being screwed to the nut,
FIG. 2B shows a state in which the bolt 1 and the nut 2 are screwed together. The bolt 1 has a rod-shaped main body 4 and a screw thread 5 that is formed by spirally projecting outward from the main body 4. On the other hand, the nut 2 has an annular main body portion 6 and a screw thread 7 formed by spirally protruding inward from the main body portion 6.

The thread 7 of the nut 2 has a tip portion 11 whose inner peripheral surface is straight and parallel to the shaft center 3, and this tip portion 11
And a side surface 13 that is inclined toward the screw bottom surface 12. The illustrated nut 2 is a metric coarse thread, and the flank angle θ between the side surfaces 13 of the screw threads 7 adjacent to each other in the cross section along the axis 3 is 60 °.

The thread 5 of the bolt 1 has a straight front end portion 21 whose outer peripheral surface is parallel to the shaft center 3, and the front end portion 21.
And flanks 23 inclined toward the screw bottom surface 22. The flank angle formed by the side surfaces 23 of the thread 5 is similar to the flank angle θ of the nut 2.

The thread 5 of the bolt 1 has a tip portion 21.
A slit 24 extending in the radial direction is formed. The slit 24 is located at the center of the screw thread 5 in the direction of the axis 3 and is continuous in a spiral shape. Therefore, the tip end portion 21 of the thread 5 passes through the slit 24 in the axial direction.
As a result of division, tip end side pressure contact portions 25 are formed on both sides of the tip end portion 21 in the axial direction. In the illustrated case, the axially outermost portion of the tip side pressure contact portion 25 is, as shown by a chain double-dashed line in FIG. 2 (a), the thread 7 of the nut 2 before being screwed. The position is almost the same as the side surface 13 or inside thereof.

On the side surface 23 of the screw thread 5, a root-side pressure contact portion 26 protruding outward in the axial direction is provided.
Is formed so as to be located slightly closer to the root side than the middle portion of the dimension in the height direction. In the illustrated case, the root-side press contact portion 26 has the nut 2 in a state before being screwed.
It projects in the axial direction so as to cross the side surface 13 of the screw thread 6.

The side surface 23 between the tip side pressure contact portion 25 and the root side pressure contact portion 26 is a concave surface, and a concave portion 27 is formed in the screw thread 5 by this concave surface. Since the concave portion 27 is formed, as shown in FIG. 2B, when the bolt 1 is screwed to the nut 2, the root-side pressure contact portion 26 moves toward the thread 5 side in the direction parallel to the axis 3. The tip end side pressure contact portion 25 is elastically deformed, and the tip side pressure contact portion 25 is elastically deformed.
Will be converted into a pressure contact force toward the side surface 13 of the thread 7. That is, when the base side pressure contact portion 26 is elastically deformed,
The tip side pressure contact portion 25 is elastically deformed so that the slit 24 is widened.

As a result, as shown in FIG. 2B, the screw thread 5 of the bolt 1 and the screw thread 7 of the nut 2 are the tip of the screw thread 5 and the portion of the side surface on the root side of the screw thread 7, Screw thread 5
The side surface on the root side of the and the tip of the screw thread 7 are in pressure contact with each other, that is, in the state of receiving pressure,
A strong frictional force acts on the threads 5 and 7. Therefore, using such a bolt 1, a nut 2
When screwed to, strong resistance to loosening is obtained,
It is possible to prevent the bolt 1 from loosening without using a spring washer or the like.

(Embodiment 2) FIGS. 3 (a) and 3 (b) are views showing a fastening member according to another embodiment of the present invention, in which parts common to those of the screw member in the above embodiment have the same reference numerals. Is attached.

In this fastening member, in the state before the bolt 1 is screwed to the nut 2 as shown in FIG. 3A, the tip side pressure contact portion 25 of the bolt 1 has the thread 7 of the nut 2.
It projects in the direction of the axis 3 so as to intersect with the side surface 13 of the. On the other hand, the tip of the base side pressure contact portion 26 is almost in contact with the side surface 13 of the thread 7 of the nut 2 or is located inside thereof.

Therefore, when the bolt 1 is screwed to the nut 2, the distal end side pressure contact portion 25 is elastically deformed so as to face inward and the width of the slit 24 is narrowed, as shown in FIG. 3B. Will be transformed into. Due to the action of the concave portion 27, this elastic deformation causes the root-side press-contact portion 26 to project axially outward, so that the root-side press-contact portion 26 is attached to the thread 7 of the nut 2.
It will be converted into the pressure contact force that makes the pressure contact.

Also in this case, as in the above-mentioned embodiment,
When the bottle 1 and the nut 2 are screw-coupled to each other, the threads 5 and 7 exert a strong frictional force on each other, and a strong resistance is generated between them, so that the bolt 1 and the nut 2 are Mutual loosening is prevented.

Although the bolt 1 and the nut 2 described above are made of carbon steel, they may be made of non-ferrous metal such as alloy steel or synthetic resin depending on the application of the screw member.

2 (a) and 3 (a) both show an enlarged view of a part of the screw thread 5 of the entire screw thread of the bolt 1 as shown by reference numeral 1a in FIG. In addition, only the portion of the tip of the bolt 1 having a pitch of 1 to 2 or 3 has a flat side surface similar to a normal bolt, and is set to have a size smaller than the thread groove on the nut side. Thus, when the bolt 1 is screwed to the nut 2, the bolt 1 can be screwed by simply rotating the bolt 1 relatively at the start of tightening. When the relative rotation is subsequently continued, the resistance becomes stronger, but the screw threads for several pitches have already completed the screw coupling, so that the screw can be relatively easily fastened even if the resistance is strong.

(Other Embodiments) In the embodiment shown in FIGS. 2 and 3, the first screw member is a bolt 1 or a male screw, but the first screw member is a nut 2 or a female screw. Is also possible. That is, the slit 24 is formed in the thread 7 of the nut 2, and the tip side pressure contact portion 25,
You may make it form the root side press contact part 26 and the recessed part 27 in the thread 7.

In the illustrated case, the present invention is applied to a metric coarse thread, but the present invention is applied to various types of thread members such as a wit screw, a unified screw, a trapezoidal screw and a pipe screw. It is possible to apply. In addition to the bolts shown in FIG. 1, the bolt 1 can be applied to hexagon socket head cap bolts and the like.

In the illustrated screw member, the depth of the slit 24, that is, the dimension in the radial direction is about half the height of the screw thread 5, and the bottom surface of the slit 24 is located at the root side pressure contact portion 26. Although it is located near the position, the slit 24 may be deeper than this. Thus, by changing the depth of the slit 24, it is possible to change the resistance force at the time of screw connection, and it is possible to adjust the degree of loosening prevention according to the application of the screw member.

(Manufacturing Method) FIGS. 4 (a) to 4 (c) are views showing a procedure for manufacturing the above-described nut 1 by plastic working. In each case, the thread 5 of the nut 1 is enlarged. Shows.

The manufacturing process of the nut 1 is basically a rough material forming step, a single-thread screw forming step of forming the rough material formed in this step into a single-thread screw, and a single-thread screw formed in this step. It has a finishing process for finishing the product.

FIG. 4A is a view showing the bolt rough material 31 after the rough material forming step is completed. The screw rough material, that is, the bolt rough material 31, is formed by the slit screw groove 32 and the product screw groove 33.
It is a double thread screw having and. Therefore, the slit screw groove 32 is spirally connected, the product screw groove 33 is spirally connected between the slit screw grooves 32, and the thread portion is also a double thread. The depth of each thread groove 32, 33 is determined by the slit 2 formed in the bolt 1.
The depth is set to be shallower than the depth corresponding to the depth of 4 when forming the rough material. In the illustrated case, the depth of the slit thread groove 32 and the depth of the product thread groove 33 are set to be the same, but the depth of the product thread groove 33 is set to be larger than that of the slit thread groove 32. It may be formed deeply.

In order to form such a bolt rough material 31, first, a carbon steel round bar is cut into a predetermined diameter and then it is formed into a predetermined diameter by using a thread rolling machine as shown in FIG. As shown in (1), it is plastically worked, powdered by sintering, or cut into the shape shown. There are flat die type thread rolling machine and round die type thread rolling machine as the thread rolling machine for rolling, but in the case shown in the figure, the flat die type thread rolling machine is used for bolt roughing. The material 31 was plastically processed.

As shown in FIG. 4 (a), a bolt raw material 31 formed into a double thread in the raw material forming step is
It is set on a rolling machine for forming double thread screw, and as shown in FIG. 4 (b), the interval, that is, the width of the slit thread groove 32 is narrowed, and the interval of the product thread groove 33 is expanded to widen the single thread screw 41 To form. That is, the slit threads 32 are plastically deformed so that the screw thread portions located on both sides of the slit thread groove 32 approach each other, and at the same time, the depth of the product screw groove 33 increases.

Next, the single-thread screw 41, which has completed the single-thread screw forming step, is set on a flat die-type thread rolling machine for finishing, and finish-molded into a final product as shown in FIG. 4 (c). At this time, the surface of the die of the finish rolling machine has a cross-sectional shape corresponding to the cross-sectional shape of the thread groove of the bolt 1, and corresponds to the root side pressure contact portion 26 shown in FIGS. 2 and 3. A convex portion corresponding to the concave groove and the concave portion 27 is formed on the rolling die.

By the finishing process, the slit thread groove 32 of the bolt rough material 31 is narrowed to become the slit 24, and at the same time, the product thread groove 33 of the bolt rough material 31 is plastically worked so as to be deeply drawn. As a result, at the time of finishing the thread groove 33, the portion corresponding to the root side pressure contact portion 26 of the bolt enters into the concave groove formed in the rolling die, and the root side pressure contact portion 26.
Is formed, and the recess 27 is formed to obtain the bolt 1 having a single thread.

As described above, in the single thread screw forming step and the finishing step, the flat die type thread rolling machine is used because the round die type thread rolling machine has a protruding portion like the root side pressure contact portion 26. This is because it is difficult to form the screw that is included, and by using a flat die, it is possible to form the screw member having the illustrated shape. In addition, FIG.
As described above in each step of FIG. 4C, plastic working may be continuously performed by one rolling machine without using a separate rolling machine.

On the other hand, the screw member may be molded by powder molding using a sintered metal, and when the screw member of synthetic resin is molded, it is molded by a resin molding device such as injection molding. Further, when a screw member made of a light metal such as aluminum is formed, it may be formed by using a die by die casting or the like.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

[0044]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.
It is as follows.

(1). When the first screw member and the second screw member are screwed together, either one of the tip side pressure contact portion and the root side pressure contact portion of the first screw member moves in the direction parallel to the axis. It elastically deforms, and the other comes into pressure contact with the side surface of the screw thread of the second screw member, both screw members are fastened together with a strong resistance force, and the loosening of both screw members is reliably prevented.

(2). First, a single-thread screw is formed by using a screw raw material of a double-thread screw, and then a final product of the screw member is formed by a finishing process, so that a screw member having a complicated shape can be formed by a simple manufacturing process. Can be formed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state in which a bolt and a nut are screwed together.

FIG. 2 is an enlarged cross-sectional view showing a main part of a fastening member according to an embodiment of the present invention, (a) shows a bolt before being screwed to a nut, and (b) is a bolt and nut being screwed. The state is shown.

FIG. 3 is an enlarged cross-sectional view showing a main part of a fastening member according to another embodiment of the present invention, (a) shows a bolt before being screwed to a nut, and (b) shows a bolt and a nut. Shows the combined state.

FIG. 4 is an enlarged cross-sectional view showing a method for manufacturing a fastening member,
(A) shows a rough material forming process, (b) shows a single thread forming process, and (c) shows a finishing process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 bolt (1st screw member) 2 nut (2nd screw member) 3 shaft center 4 body part 5 screw thread 6 body part 7 screw thread 11 tip part 12 screw bottom surface 13 side surface 21 tip part 22 screw bottom surface 23 side surface 24 slit 25 Tip side pressure contact part 26 Root side pressure contact part 27 Recess 31 Bolt rough material (screw rough material) 32 Slit screw groove 33 Product screw groove 41 Single thread screw

Claims (3)

[Claims] 1. A first screw member having a first screw thread, which has a tip portion and a side surface and which is formed to spirally project from the screw body portion, and a screw body having a tip portion and a side surface and spiraled from the screw body portion. A second screw member that has a second screw thread that is formed to project in a circular shape, and that is screwed to the first screw member by relative rotation about an axis. A slit extending radially from the tip of the first screw thread is formed, and a tip-side press contact portion that presses against a side surface of the second screw thread is formed at the tip portion of the first screw thread, the first screw A root-side press-contact portion that press-contacts the side surface of the second screw thread is formed on the side surface of the crest, and when the first screw member and the second screw member are screwed together, the tip-side press-contact portion is The elastic deformation parallel to the one axis of the root side pressure contact portion is directed to the other second screw thread. Cormorants recesses for converting into pressure contact force, the fastening member, characterized in that formed is positioned between the second said the side surface of the thread tip-side press-contacting portion and the base-side press-contacting portion. 2. The fastening member according to claim 1, wherein the first screw member is one of a male screw and a female screw, and the second screw member is another screw of the male screw and the female screw. 3. A thread is formed with a slit extending in a radial direction from a tip end portion thereof, a tip side pressure contact portion and a root side pressure contact portion are formed on a side surface of the screw thread, and a recess is formed between these pressure contact portions. A method for manufacturing a fastening member for manufacturing a formed screw member, which has a double thread including a slit screw groove corresponding to the slit and a product screw groove corresponding to the screw groove between the screw threads. Rough material forming step of forming a screw rough material, and narrowing the gap between the slit screw grooves by using a flat rolling die, and expanding the gap between the product screw grooves to form a single thread screw forming A step of forming a recess on the side surface of the thread of the single-thread screw using a flat rolling die, and forming the root-side pressure contact portion and the recess while deepening the product thread groove of the single-thread screw. And form the screw A method of manufacturing a fastening member, the method including: