JPWO2020032013A1 - Male screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a male screw capable of removing a shaft portion of a broken male screw remaining while being screwed to an object to be fastened in as few steps as possible.
SOLUTION: A head (14) having a top surface (14a) and a bottom surface (14b) and one end surface (12b) are circular, and the end surface (12b) is the bottom surface (14b) of the head. The male screw (10) having a substantially cylindrical or substantially conical shaft portion (12) connected to the head portion (14) has a hole portion (20) formed in the straight direction from the head portion (14) to the shaft portion (12). Is provided, and the hole portion (20) extends from the diameter center portion of one end surface (12b) of the shaft portion along the central axis of the shaft portion.
[Selection diagram] Fig. 3

Description

The present invention relates to male threads.

Male screws are widely used as a fixing tool for fastening separate members to each other. The male screw has a cylindrical or conical shaft portion, and a thread is provided on the outer surface of the shaft portion. The male screw further has a head that is connected to the shaft and receives rotational force from the outside.

Male threads are sometimes referred to as bolts and are used in combination with female threads such as nuts. Alternatively, it is used by making a screw mark that acts as a female screw in advance on the member itself to be fastened to one member, and then engaging the screw thread of the male screw with the screw mark of the member, in other words, screwing it. Alternatively, there is also one used in which a male screw is directly screwed into a member to be fastened and the male screw is directly fastened to the member, such as a wood screw.

In this way, the male screw is used in various situations, but it breaks from the vicinity of the connecting part between the head and the shaft, for example, due to aged deterioration during the fastening work or in the state where the members are fastened to each other. It may end up. In this case, since the rotational force in the direction of unscrewing the male screw and the female screw cannot be applied to the shaft portion via the head portion, it is difficult to remove the broken shaft portion from the object to be fastened. In particular, when the shaft portion of the male screw remains in the so-called blind hole where the screw mark does not penetrate to the back side of the member, the work of removing the shaft portion from the blind hole becomes extremely difficult.

However, the work of removing the shaft portion of the broken male screw is a very difficult work for the maintenance manager of the equipment using the male screw as a fixing tool. For example, a maintenance manager needs various tools to perform the work of removing the shaft portion. Furthermore, depending on the location of the equipment and the location where the male screw is used, it is often the case that there is not enough space for the maintenance manager to perform the removal work using various instruments.

Since the conventional male screw has such a problem, even if the male screw is broken, the equipment to be used is kept to a minimum, and the shaft part of the broken male screw that remains screwed to the object to be fastened is removed. There has been a demand for a male screw that can be removed in as few steps as possible.

In order to solve such a problem, the present invention adopts a substantially cylindrical or substantially conical shape in which a head having a top surface and a bottom surface and at least one end surface are circular surfaces, and one end portion. The surface is a male screw having a shaft portion connected to the bottom surface of the head, and a hole portion is provided in the straight direction from the head portion to the shaft portion, and the hole portion is the diameter center of one end surface of the shaft portion. Provided is a male screw extending from the portion along the central axis of the shaft portion.

According to the male screw according to the present invention, for example, even if the male screw is broken while being screwed to the object to be fastened, the remaining portion can be easily removed from the object to be fastened, which is a peculiar effect.

It is a front view of the Example of the male screw which concerns on this invention. It is a top view of the Example of the male screw shown in FIG. FIG. 5 is a cross-sectional view of a male screw broken along the breaking line III-III shown in FIG. 2 according to an embodiment of the present invention. It is sectional drawing of another Example which concerns on this invention. It is sectional drawing of the state in which the shaft part of the Example of FIG. 1 remains in a blind hole while being broken. It is a figure which shows the example of the process of removing the broken shaft part which remains in the state of FIG.

Next, an embodiment of the male screw according to the present invention will be described in detail with reference to the accompanying drawings. In the embodiment of the male screw 10 according to the present invention, as shown in FIG. 1, the shaft portion 12 which is a portion screwed with the female screw and fastened to each other is connected to one end of the shaft portion to improve the efficiency of rotational force. It has a head 14 that transmits to the receiving shaft portion 12.

In the case of this embodiment, the shaft portion 12 has a substantially columnar shape, and a spiral thread 16 is formed on the surface of the shaft portion 12. Further, in this embodiment, the top surface of the male screw 10 is the top surface 14a of the head 14, and the screw tip of the male screw 10 is the bottom surface 12a of the cylindrical shaft portion 12.

Further, the head 14 has a bottom surface 14b on the opposite side of the top surface, and the shaft portion has a circular top surface 12b on the end opposite to the end with the bottom surface 12a. The bottom surface 14b of the head portion 14 and the top surface 12b of the shaft portion 12 serve as a connecting portion between the shaft portion 12 and the head portion 14 as described above. Of course, even when the shaft portion 12 has a substantially conical shape, the top surface 12b of the shaft portion 12 has a circular shape, so that the top surface 12a of the circular shape and the top surface 12b of the shaft portion 12 are members of each other. It becomes a connecting surface. The shape of the shaft portion 12 may be such that the main body portion has a substantially cylindrical shape or a substantially conical shape. For example, the main body portion may have a columnar shape but the bottom surface 12a may be sharp.

Further, as can be easily grasped from FIG. 2, the male screw 10 according to the present embodiment is a hexagon socket head bolt provided with a hexagonal hole, that is, a recess 18 at the top of the head 14, and has the dimensions of the recess 18. It is used by applying a rotational force to the male screw 10 using a hexagon wrench corresponding to. However, it goes without saying that the type of male screw 10 according to the embodiment of the present invention is not limited to the hexagon socket head cap screw. For example, a hole or groove having an arbitrary shape such as a square hole, a cross hole, or a pickpocket, that is, a recess 18, may be provided on the top side of the head 14. Alternatively, the male screw 10 of a type that applies a rotational force by sandwiching the side surface of the head 14 with a tool such as a spanner may be used without providing the recess 18 on the top surface of the head 14.

On the bottom surface of the recess 18 provided in the head 14, a hole 20 is formed which leads to a shaft portion 12 connected to the head 14. The hole 20 is opened from the bottom surface of the recess 18 so as to extend along the axial direction at the center of the diameter of the shaft 12. That is, the position where the hole portion 20 is provided coincides with the position extending straight from the diameter center portion of the top surface 12b of the shaft portion 12 along the central axis of the shaft portion 12. In the case of a male screw 10 having no recess 18, the hole 20 is opened so as to extend from the center of the top surface 14a of the head 14 to the center of the diameter of the shaft 12 along the axial direction. Be done.
In other words, at least inside the shaft portion 12, and preferably inside the head portion 14, a wall surface for partitioning the hole portion 20 is formed.

By providing the male screw 10 with the hole 20, the object to be fastened does not require any tool other than a tool that can be inserted into the hole 20 and can apply a rotational force to the shaft portion 12, such as an extractor. It is possible to remove the shaft portion 12 of the broken male screw 10 that remains while being screwed to.
In this way, the diameter of the hole 20 allows the tool to be inserted and more efficiently rotates from the tool so that the broken shaft 12 can be easily removed from the object to be fastened using only a minimum of tools. It is preferable that the dimensions are suitable for receiving a force, and it is necessary to select an appropriate dimension for the diameter of the hole 20 depending on the size of the bolt or the like. More specifically, although it may change depending on the diameter and material of the shaft portion 12, when the diameter of the hole portion is R1 and the diameter of the top surface of the shaft portion 12 is R2, the ratio of R1 to R2 ( R1 / R2) is preferably 0.15 to 0.35.

Further, in consideration of various conditions such as the total length L1 of the shaft portion 12, the material forming the shaft portion 12, and the assumed situation in which the male screw 10 is used, the male screw 10 can be opened, more specifically, the male screw 10. The length L2 of the hole 20 formed in the shaft 12 is finally determined. It is preferable to set the ratio of the shaft portion length L2 of the hole portion 20 to the total length L1 of the shaft portion 12 to at least about 90% from the viewpoint of the strength of the male screw 10. That is, in this case, only the length (L3 shown in FIG. 3) of about 10% from the tip portion 12a of the shaft portion to be the screw tip is left without opening the hole portion 20.

However, considering that the shaft portion 12 may break near the screw tip, it is preferable to make the ratio of the shaft portion length L2 of the hole portion 20 to the total length L1 of the shaft portion 12 as large as possible. Although it varies depending on various conditions such as the total length L1 of the shaft portion 12, the material forming the shaft portion 12, and the assumed phase in which the male screw 10 is used, the length L2 of the hole portion 20 with respect to the total length L1 of the shaft portion 12 The ratio of can be set between 95% and 97% at the maximum. That is, in this case, only the length of 3% to 5% from the tip portion 12a of the shaft portion to be the screw tip is left without opening the hole portion 20.

In order to make a hole 20 in the male screw 10, a known instrument may be used arbitrarily. For example, a drilling machine may be used to open a hole 20 having a width of 1.0 mm to 1.5 mm so that L2 / L1 ≦ 0.97.
When the hole 20 of the male screw 10 is configured to penetrate from the bottom surface of the recess 18 to the tip portion 12a of the shaft portion, when the male screw 10 fastened to the through hole breaks, from the side of the tip portion 12a of the shaft portion. It is also possible to use a tool to remove the remaining part of the broken male screw 10.

The configuration of another embodiment of the present invention will also be described. In this embodiment, as shown in FIG. 4, in addition to the configuration of the male screw 10 described in the previous embodiment, the hole 20 is filled with a resin, particularly a plastic substance 22 such as a synthetic resin. ing. As the plastic substance 22, a substance having flexibility enough to smoothly insert a tool such as an extractor into the hole 20 when removing the broken shaft 12 is used. The plastic material 22 is preferably filled up to the height of the bottom surface of the recess 18.

By filling the hole 20 with the plastic substance 22 in this way, it is possible to obtain an advantageous effect that the strength of the male screw 10 in which the hole 20 is formed can be increased. Further, by filling the plastic substance 22, it is possible to prevent foreign substances such as dust and liquid from entering the hole 20. Therefore, smooth insertion of a tool such as an extractor into the hole 20 is always ensured, and it is possible to prevent a situation in which the wall surface and the bottom surface of the hole 20 are corroded by the influence of foreign matter.

Subsequently, an example of a step of removing the remaining portion of the broken male screw 10 while being fastened to the blind hole in the case of using the embodiment of the male screw 10 according to the present invention will be described. FIG. 5 shows a cross-sectional view of the shaft portion 12 of the male screw 10 which has been separated from the head 14 while being screwed into the blind hole 32. When the head portion 14 is bent in this way, the head portion 14 that efficiently transmits the rotational force to the shaft portion is no longer connected to the male screw 10, so that the shaft portion 12 is provided with a hole 20 in advance like the conventional male screw. If not, the task of removing the broken shaft 12 from the blind hole 32 becomes extremely difficult.

When the male screw 10 according to the embodiment of the present invention is broken, in order to remove the broken shaft portion 12 from the blind hole 32, first, a tool 34 such as an extractor remains in the blind hole 32. It is inserted into the hole 20 provided in the shaft portion 12 of the male screw 10.
After inserting the tool 34 into the shaft portion 12, the tool 34 is operated to give the shaft portion 12 a rotational force in the direction of unscrewing the blind hole 32. More specifically, when the male screw 10 is a male screw of a type in which the male screw 10 is screwed into the blind hole 32 by rotating it clockwise, that is, clockwise, the tool 34 is inserted into the hole 20 of the shaft portion 12. Then, a counterclockwise rotational force F is applied to the bent shaft portion 12. When the broken shaft portion 12 receives the rotational force F in the counterclockwise direction, it is converted into a linear motion toward the inlet direction A of the blind hole 32, and eventually the broken shaft portion 12 and the blind hole 32 are screwed together. Is solved. Of course, for the male screw 10 which is screwed with the female screw by rotating in the counterclockwise direction, a tool 34 may be used to apply a rotational force in the clockwise direction to the bent shaft portion 12.

Even in the case of the male screw 10 of the embodiment in which the hole 20 is filled with the plastic substance 22, the tool 34 can be inserted into the hole 20 as it is so as to break through the plastic substance 22. The tool 34 used at this time is preferably of a type in which the plastic substance 22 is discharged from the inlet of the hole 20 as the tool 34 is inserted toward the tip of the hole 20.

As described above, when the embodiment of the male screw 10 according to the present invention is used as a fastener, even if the shaft portion 12 of the male screw 10 is broken while being screwed into the blind hole 32, it is largely removed for the operator and the tool. The removal work can be easily completed by using only one kind of tool 34 such as an extractor without requiring a work space. That is, if the embodiment of the male screw 10 according to the present invention is used, it is not necessary to perform a process other than applying a rotational force using the tool 34 to remove the shaft portion 12 remaining in the blind hole, which is troublesome for the operator. Will be greatly reduced.

Up to this point, the configuration and handling method of the examples of the present invention have been described, but the present invention is not limited to the above-described examples described with reference to the drawings. It will be apparent to those skilled in the art that various modifications and substitutions can be made without departing from the scope of the attached claims and the gist thereof.

10 male screw
12 Shaft
14 head
20 holes
22 Plastic substances

Claims (4)

With a head with a top and bottom,
In a male screw having a substantially cylindrical or substantially conical shape in which at least one end surface is a circular surface, and the one end surface has a shaft portion connected to the bottom surface of the head.
The male screw is provided with a hole formed in a straight direction from the head portion to the shaft portion, and the hole portion extends from the diameter center portion of one end surface of the shaft portion to the central axis of the shaft portion. A male screw characterized by extending along it. The male screw according to claim 1, wherein the length of the portion of the hole portion provided on the shaft portion is within 97% of the total length of the shaft portion. The male screw according to claim 1 or 2, wherein the ratio (R1 / R2) of the diameter R1 of the hole to the diameter R2 of the top surface of the shaft is 0.15 to 0.35. .. The male screw according to any one of claims 1 to 3, wherein the hole is filled with a plastic substance.

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