Sealed screws

Abstract

To provide a seal screw capable of preventing damage to an elastic ring.SOLUTION: A seal screw 10 is composed of: a screw component 11 comprising a neck lower part 13 formed between a head part 12 and a male screw 15 and having a diameter larger than an outer diameter of the male screw 15 and smaller than an outer diameter of the head part 12; and an elastic ring 16 attached to the neck lower part 13 of the screw component 11. On an outer periphery of the neck lower part 13, a concave-shaped temporary fixing groove 14 into which the elastic ring 16 is fitted is formed. This prevents the elastic ring 16 attached to the screw component 11 from coming into contact with a corner part, making it possible to prevent damage to the elastic ring.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a seal screw having an elastic member attached to a shaft portion.

Background Art

[0002] Conventionally, in a seal screw in which an elastic ring is attached to a shaft portion of a screw member having a head portion and a shaft portion to seal a gap with a fastened member, there is known one in which the elastic ring 101 is prevented from coming off the screw member 102 as shown in Patent Document 1. For example, in the seal screw 100 of Patent Document 1, as shown in FIG. 6, the inner diameter of the elastic ring 101 is smaller than the outer diameter of the thread 104 formed on the shaft portion 103, and the elastic ring 101 is configured to be locked to the thread 104. In addition, as shown in FIG. 7, there is also known a seal screw 200 in which an annular groove 204 into which an elastic ring 201 fits is formed on the outer periphery of the shaft portion 203, and the elastic ring 201 is fitted into the annular groove 204 to prevent it from coming off.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the seal screw 100 described in Patent Document 1, during transportation, when the elastic ring 101 shakes, the thread 104 may bite into the elastic ring 101, and the elastic ring 101 may be damaged at its tip. In addition, in the seal screw 200 described in FIG. 7, when inserted into the fastened member 205, the corner portion of the annular groove 204 may bite into the elastic ring 201 and damage the elastic ring 201. Therefore, in these seal screws 100 and 200, there is a risk that the elastic members 101 and 201 may be damaged during transportation or fastening, and there are problems such as the confidentiality being impaired due to the damage. [Means for solving the problem]

[0005] The present invention was created in view of the above problems and aims to provide a sealing screw capable of preventing damage to an elastic ring. To achieve this objective, the present invention provides a sealing screw comprising a screw component having a neck portion between the head and the male thread that is larger in diameter than the outer diameter of the male thread and smaller in diameter than the outer diameter of the head, and an elastic ring attached to the neck portion of the screw component, wherein a concave curvature temporary fixing groove for fitting the elastic ring is formed on the outer circumference of the neck portion. Preferably, the inner diameter of the elastic ring is smaller than the outer diameter of the neck portion. Furthermore, preferably, the circumferential cross-section of the elastic ring is circular. Moreover, preferably, the temporary fixing groove has a larger radius of curvature than the elastic ring. Furthermore, preferably, the temporary fixing groove is formed by rolling. [Effects of the Invention]

[0006] According to the sealing screw of the present invention, an elastic ring is fitted into a temporary fixing groove formed in the lower part of the neck, which is larger than the outer diameter of the male screw, so that the elastic ring does not come into contact with the corners after installation. This has the advantage of preventing damage to the elastic ring during transport, etc. Furthermore, since the inner diameter of the elastic ring is smaller than the outer diameter of the lower part of the neck, it has the advantage of preventing the elastic ring from falling off the screw part during transport. In addition, since the circumferential cross-section of the elastic ring is configured to be circular, the contact area between the elastic ring and the screw part is reduced. This has the advantage of allowing the elastic ring to move smoothly during fastening. Moreover, since the temporary fixing groove has a larger radius of curvature than the elastic ring, a gap is created between the elastic ring and the temporary fixing groove, which has the advantage of making it easier for the elastic ring to move. Furthermore, since the temporary fixing groove is formed by rolling, it has the advantage of enabling the screw part to be manufactured quickly and inexpensively. [Brief explanation of the drawing]

[0007] [Figure 1]This is a partial cross-sectional side view showing the state of the seal screw according to the present invention before it is screwed into the fastening member. [Figure 2] This is an enlarged view of section A in Figure 1. [Figure 3] This is a partial cross-sectional side view showing the state after the seal screw according to the present invention has been screwed into a fastening member. [Figure 4] This is an explanatory diagram showing the thread rolling process for a seal screw according to the present invention, and is a partial cross-sectional side view showing the state at the start of the thread rolling process. [Figure 5] This is an explanatory diagram showing the thread rolling process for a seal screw according to the present invention, and is a partial cross-sectional side view showing the state at the end of the thread rolling process. [Figure 6] This is a partial cross-sectional side view showing the structure of a conventional seal screw disclosed in Patent Document 1. [Figure 7] This is a partial cross-sectional side view showing the structure of a conventional seal screw disclosed in Patent Document 2. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to the drawings. In Figure 1, 10 is a sealing screw 10, and as shown in Figure 2, this sealing screw 10 is composed of a screw component 11 which is a rod-shaped member with a head and an elastic ring 16 which is attached to this screw component 11.

[0009] As shown in Figure 1, the screw component 11 of this seal screw 10 is integrally molded with a head 12, a neck portion 13 continuous with the head 12, and a male thread 15 continuous with the neck portion 13. The head 12 is configured as a disc shape having a predetermined thickness, and the neck portion 13 is continuous with its lower surface. The neck portion 13 is configured as a cylindrical shape with a smaller outer diameter than the head 12, and a temporary fixing groove 14 is formed on its outer circumference. The male thread 15 is continuous with the lower end of the neck portion 13. The outer diameter of the male thread 15 is configured to be the same as or slightly smaller than the neck portion 13.

[0010] The temporary fixing groove 14 is an annular groove formed in a concave curved shape, with its bottom located at the center in the height direction. The elastic ring 16 is fitted into this temporary fixing groove 14. The elastic ring 16 is an O-ring made of a flexible resin, and its circumferential cross-section is circular. The inner diameter of the elastic ring 16 is smaller than the outer diameter of the neck portion 13 and is approximately the same diameter as the bottom of the temporary fixing groove 14. Therefore, the elastic ring 16 fitted into the temporary fixing groove 14 is prevented from coming off by its own tension. Furthermore, the elastic ring 16 is designed so that the diameter of its circumferential cross-section is wider than the width of the temporary fixing groove 14, while its radius r1 is smaller than the radius of curvature r2 of the temporary fixing groove 14. Therefore, as shown in Figure 2, the elastic ring 16 fitted into the temporary fixing groove 14 abuts against the bottom of the temporary fixing groove 14, while forming a slight gap between it and the rest of the temporary fixing groove 14. With these structures, when the elastic ring 16 is pressed towards the head 12, the elastic ring 16 can move along the temporary fixing groove 14, as shown by the dashed line in Figure 3.

[0011] The fastening member 20 that screws into the seal screw 10 has a female thread that can be screwed into the male thread 15, and in this embodiment, it is a nut. The fastened member 30 fixed by the seal screw 10 and the fastening member 20 has an insertion hole 31 into which the seal screw 10 can be inserted. This insertion hole 31 is configured as a stepped structure consisting of a large diameter portion 32 that opens towards the head 12 side of the seal screw 10 and a small diameter portion 33 that communicates with the large diameter portion 32 and penetrates towards the fastening member 20 side. The diameter of the large diameter portion 32 is set to be smaller than the outer diameter of the head 12 of the seal screw 10 and larger than the outer diameter of the elastic ring 16, and its depth is set to be shorter than the diameter of the circumferential cross-section of the elastic ring 16. Therefore, after fastening, the deformed elastic ring 16 can be contained within the large diameter portion 32. On the other hand, the small diameter portion 33 is configured to have a diameter that is larger than the outer diameter of the neck portion 13 by a clearance T1. The clearance T1 between the small diameter portion 33 and the neck portion 13 is set to be sufficiently smaller than the difference T3 between the radius r1 of the circumferential cross-section of the elastic ring 16 and the depth dimension T2 of the temporary fixing groove 14. Therefore, when the seal screw 10 is inserted into the insertion hole 31, the elastic ring 16 can stably contact the stepped portion 34 which is the boundary between the large diameter portion 32 and the small diameter portion 33.

[0012] The operation of the above-mentioned sealing screw 10 will be explained below. First, when the seal screw 10 is inserted into the insertion hole 31, the seal screw 10 stops when the elastic ring 16 comes into contact with the stepped portion 34 at the boundary between the large diameter portion 32 and the small diameter portion 33. If the head 12 of the seal screw 10 is further pushed toward the male screw 15 in this state, the elastic ring 16 comes out of the temporary fixing groove 14. At this time, because the temporary fixing groove 14 has a concave shape, there are no corners that bite into the elastic ring 16 when it moves. Therefore, damage to the elastic ring 16 is prevented. In addition, since the circumferential cross-section of the elastic ring 16 is configured to be circular, the contact area with the screw part 11 is small, so the elastic ring 16 can move smoothly. In this way, the elastic ring 16 that has moved relative to the head 12 side is elastically deformed as it is sandwiched between the head 12 and the stepped portion 34, as shown in Figure 1. At this time, as described above, the neck portion 13 is made larger than the thread diameter of the male screw 15, and the center diameter of the elastic ring 16 is sufficiently larger than the hole diameter of the small diameter portion 33, so the contact area between the elastic ring 16 and the stepped portion 34 is increased. This has advantages such as improved airtightness between the head 12 and the fastened member 30. In addition, the deformed elastic ring 16 is less likely to come into contact with the corner of the stepped portion 34, which has advantages such as the elastic ring 16 being less likely to be damaged. After that, as shown in Figure 1, the fastening member 20 is placed on top of the fastened member 30 and the fastening member 20 is screwed onto the male screw 15.

[0013] Furthermore, as described above, the elastic ring 16 is fitted into the temporary fixing groove 14 formed in the screw part 11 of the sealing screw 10, so the elastic ring 16 will not fall off. Moreover, during transport, the elastic ring 16 is in contact with the concave curved surface of the temporary fixing groove 14 and does not come into contact with sharp angles such as screw threads. Therefore, it is possible to prevent the elastic ring 16 from being damaged during transport. In addition, by fitting into the temporary fixing groove 14, which has a smaller diameter than the neck portion 13, the elongation of the elastic ring 16 is small, and permanent deformation is reduced, resulting in advantages such as being less prone to deterioration.

[0014] Note that the specific configuration of each part of the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention. For example, the head 12 is not limited to a disc shape, and there is no problem even if it has other shapes such as a hexagonal prism shape. Also, various dimensions of the lower neck portion 13 and the elastic ring 16 can be appropriately designed according to the thickness of the fastened member 30, the hole diameter of the large-diameter portion 32, etc. Further, it is preferable that various dimensions of the temporary fixing groove 14 are appropriately changed according to the size of the elastic ring 16.

[0015] Also, the screw component 11 may be such that the temporary fixing groove 14 is formed by forging in the same manner as the male screw 15. For example, as shown in FIG. 4, for a preform 17 before the temporary fixing groove 14 and the male screw 15 are formed in the lower neck portion 13' and the shaft portion 18, a pair of forging dies 40, 41 having unevenness 43 formed symmetrically with the desired temporary fixing groove 14 and male screw 15 are used to sandwich and perform forging. As a result, the unevenness 43 formed on the forging dies 40, 41 is transferred to the outer periphery of the preform 17, and as shown in FIG. 5, the temporary fixing groove 14 and the male screw 15 are formed to become the screw component 11. When the temporary fixing groove 14 is formed by forging in the same manner as the male screw 15 in this way, the screw component 11 can be manufactured faster and at a lower cost than when only the temporary fixing groove 14 is formed by cutting or the like separately from the male screw 15. Thereafter, by attaching the elastic ring 16 to the screw component 11, it becomes the sealing screw 10. Of course, there is no problem even if a second and third fastened member (not shown) is sandwiched between the fastened member 30 and the fastening member 20.

Explanation of Reference Numerals

[0016] 10 … Sealing screw 11 … Screw component 12 … Head 13 … Lower neck portion 14 … Temporary fixing groove 15 … Male screw 16 … Elastic ring 20 … Fastening member 30 … Fastened member

Claims

1. A sealing screw comprising a screw component having a neck portion between the head and the male thread that is larger in diameter than the outer diameter of the male thread and smaller in diameter than the outer diameter of the head, and an elastic ring attached to the neck portion of the screw component, A sealing screw characterized in that a concave temporary fixing groove is formed on the outer circumference of the lower part of the neck into which the elastic ring is fitted, and the width of the elastic ring is set to be greater than the width of the temporary fixing groove.

2. The sealing screw according to claim 1, characterized in that the elastic ring has an inner diameter smaller than the outer diameter of the neck portion.

3. The sealing screw according to claim 1, characterized in that the elastic ring has a circular cross-section in the circumferential direction.

4. The sealing screw according to claim 3, characterized in that the temporary fixing groove has a larger radius of curvature than the elastic ring.

5. The sealing screw according to claim 1, characterized in that the temporary fixing groove is formed by a rolling process.

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