JP4546137B2 - Screw fall prevention device - Google Patents

Description

  The present invention relates to a screw drop prevention device in a two-member screwing structure in which a first member and a second member are screwed together.

As a first example of a conventional screw drop prevention device, a screw with a screw lock agent is used.
Further, as a second example, a washer-attached washer with a tongue stop is disposed on the contact surface between the lower surface of the screw head and the member.
Further, a third example of the screw drop prevention device is shown in FIGS.
FIG. 8 is a longitudinal sectional view.
FIG. 9 is a top plan view of FIG.
Reference numeral 10 denotes a first member, and a female screw hole 11 is formed in an upper end surface 10a with which a second member to be described later contacts.
Reference numeral 12 denotes a second member that is brought into contact with and screwed to the first member, and has a screw insertion hole 13 penetrating from the screw mounting surface 12a toward the lower end surface 12b.
A cylindrical portion 12c having a diameter larger than the diameter Ds of the screw head Sa of the screw S is formed on the screw mounting surface 12a on the outer peripheral side of the screw insertion hole 13 so as to open upward. On the inner diameter portion 12d of 12c, a plurality of (two in opposition in this example) restricting protrusions 12e are formed to protrude further inward.
And the distance D12 between the opposing surfaces of the said opposing control protrusion 12e is formed smaller than the diameter Ds of screw head Sa.
Furthermore, a fourth example of the screw drop prevention device is shown in FIGS.
FIG. 10 is a longitudinal sectional view.
FIG. 11 is a top plan view of FIG.
The first member 10 is the same member as in FIG.
The second member 12 is provided with a plurality of locking pieces 12e (two facing in this example) protruding upward on a screw mounting surface 12a on the outer peripheral side of the screw insertion hole 13 and locking. The upper end of the piece 12e is formed with a restricting protrusion 12f that protrudes inward.
The distance D12 between the opposing surfaces of the restricting protrusion 12f is formed smaller than the diameter Ds of the screw head Sa.

According to the first example of such a conventional screw drop prevention device, the screw is bonded and held by the lock agent (adhesive) in a state where the first member and the second member are screwed together.
On the other hand, when releasing the screwed state between the first member and the second member, the screw is rotated against the adhesive force of the locking agent, and the screw is removed.
When such a screw with a locking agent is used, the adhesive force of the locking agent is reduced due to repeated attachment / detachment of the screw, and the repeated use cannot be performed.
Also, when removing the screw against the adhesive force of the adhesive, there is a risk of damaging the bit, which would apply an excessive force to the bit on the screw head.

  Further, according to the second conventional example using a washer with a tongue, the elastic force of the washer is reduced by repeated attachment / detachment of the screw, and there is a limit to repeated attachment / detachment.

そして、ネジ頭部Ｓａに対する規制突部１２ｅの規制代Ｇは、（Ｄｓ−Ｄ１２）によって決定されるもので、この規制代Ｇを片側で１．５ｍｍに設定すると、ネジ頭部形状の異なるネジに対して対向面間の距離Ｄ１２は下表の如く異なってくる。

以上によると、例えば平丸ネジに適する対向面間の距離D１２（１１mm）を設定すると、
丸ネジ、メクラ孔ネジに対して充分な規制代Ｇを確保できない。
一方、丸ネジに適する対向面間の距離Ｄ１２（７．５ｍｍ）を設定すると、
平丸ネジに対する規制代Ｇが過大となり、規制突部１２ｅへの円滑な進入が行なわれにくく、規制突部１２ｅの破損につながる。 Further, according to the third and fourth examples of the prior art, the first member 10 and the second member 12 are screwed together as follows.
The lower end surface 12b of the second member 12 is disposed in contact with the upper end surface 10a of the first member 10, and in this state, the screw S is inserted into the cylindrical portion 12c of the second member 12 and through the screw insertion hole 13. The male screw Sb of the screw S is screwed into the female screw hole 11 of the first member 10.
According to the above, the screw head Sa expands the regulation protrusion 12e in the original position sideways and enters the cylinder portion 12c, and then the lower surface of the screw head Sa abuts on the screw mounting surface 12a. The second member 12 is screwed toward the first member 10.
In this screwed state, the restricting protrusion 12e returns to the original position again.
Then, in the screwed state of the first member 10 and the second member 12, if the screw S is urged and the screw S does not escape upward, the screw head Sa is placed above it by the restricting projection 12e. Directional movement is suppressed, and this prevents the screw S from falling off.
According to the third and fourth examples, first, the material of the second member 12 is limited to a material having elasticity, for example, a synthetic resin material, and a rigid material cannot be used as the second member.
That is, the degree of freedom in selecting the material of the second member 12 is hindered.
Secondly, even screws having the same male screw diameter cannot be used for different screw head shapes.
For example, in the case of a male screw diameter of 6 mm, the screw head diameter Ds differs as shown in the table below due to the difference in screw head shape.

The regulation margin G of the regulation projection 12e with respect to the screw head Sa is determined by (Ds-D12). If this regulation margin G is set to 1.5 mm on one side, screws with different screw head shapes are used. On the other hand, the distance D12 between the opposing surfaces differs as shown in the table below.

According to the above, for example, when setting the distance D12 (11 mm) between the facing surfaces suitable for a flat round screw,
Sufficient regulation allowance G cannot be secured for round screws and screw holes.
On the other hand, when setting the distance D12 (7.5 mm) between the opposing surfaces suitable for the round screw
The regulation allowance G for the flat round screw becomes excessive, and it is difficult to smoothly enter the regulation projection 12e, resulting in damage to the regulation projection 12e.

  The screw drop-off prevention device according to the present invention has been made in view of the above-mentioned problems. The purpose of the device is to have a high degree of freedom in selecting the material of the second member and to cope with differences in the screw head shape. It is an object of the present invention to provide a screw drop prevention device when two members are screwed that can be used repeatedly over a long period of time.

The screw drop prevention device according to the present invention, in order to achieve the above-mentioned object, a first member having a female screw hole drilled toward the upper end surface;
In the two-member screwing device that is arranged on the upper end surface of the first member, and that screwes the second member having the screw insertion hole facing the female screw hole toward the first member with a screw,
Screw caps made of synthetic resin material
An upper annular collar,
A thin-walled cylindrical portion that is continuously provided downward from the annular flange portion and that opens downward;
A plurality of locking pieces formed by cutting upward from the lower end of the thin tube portion;
A locking projection formed to protrude outward from the outer periphery of the locking piece;
A regulating projection formed to project inward from the inner periphery of the locking piece,
Formed by
On the other hand, the second member is formed with a cap insertion tube portion into which a thin tube portion of a screw cap can be inserted on the outer peripheral side of the screw insertion hole. An engagement groove or an engagement hole capable of engaging and disposing the locking projection of the screw cap is formed,
The second member is arranged on the upper end surface of the first member and a screw is screwed into the female screw hole through the screw insertion hole, and then the thin tube portion of the screw cap is inserted and arranged in the cap insertion tube portion, and the screw cap Engaging the locking protrusion in the engaging groove or the engaging hole of the second member;
The first feature is that the restricting protrusion of the screw cap is disposed facing the screw head.

  Further, in addition to the first feature, the present invention has a second feature that the inner diameter of the restricting protrusion is larger than the outer diameter of the driver that rotates the screw.

  Furthermore, in addition to the first feature, the present invention has a third feature that the screw facing surface formed on the restricting protrusion is an inclined surface whose diameter is reduced from below to above.

According to the first feature of the present invention, in the state where the second member is screwed toward the first member with a screw, the screw cap is inserted and disposed in the cap insertion tube portion, and the locking protrusion of the locking piece portion Is engaged and disposed in an engagement groove provided in the cap insertion tube portion of the second member, whereby the screw cap is fixedly disposed in the cap insertion tube portion.
In such a state, the restriction protrusion of the screw cap is arranged facing the screw head, so that even if Yurumi occurs on the screw, the screw head contacts the restriction protrusion and the screw may fall off. Deterred.
Here, since the screw cap is divided and formed with respect to the second member, the second member may be made of any material, and the degree of freedom in selecting the material of the second member formed as a product is increased. It can be improved.
Moreover, since it is not necessary to insert a screw between the opposing surfaces of the restricting protrusions of the screw cap, it is possible to improve the adaptability to the screw head shape difference.
Further, the screw cap is formed of a synthetic resin material, and the locking piece including the locking protrusion is elastically deformed so that the locking protrusion can be detached from the engagement groove of the cap insertion cylinder portion, so that it can be used for a long time. It is stable and can be used repeatedly.

  Further, according to the second feature of the present invention, the screw can be screwed toward the first member while the screw is inserted into the screw insertion hole of the second member and the screw cap is mounted on the second member. A screw can be arranged in advance on the second member, and the assembly of the screw can be improved.

  Furthermore, according to the third feature of the present invention, if the screw is erupted and the screw moves upward in the escape direction, the screw head presses the locking protrusion outward, so that the screw Even if the force in the Yurumi direction acts on the screw cap, the screw cap does not come off unnecessarily.

Hereinafter, an embodiment of a screw drop prevention device according to the present invention will be described with reference to the drawings.
The first member and the second member will be described with reference to FIG.
Reference numeral 1 denotes a first member, which is formed by opening a female screw hole 1b toward its upper end surface 1a.
Reference numeral 2 denotes a second member in which the upper end surface 2a abuts against the upper end surface 1a of the first member, and a screw mounting surface 2b forming a flat surface is inserted into a screw facing the female screw hole 1b of the first member 1. The hole 2c is drilled through.
Further, a cap insertion cylinder portion 2d that opens upward is formed on the outer peripheral side of the screw insertion hole 2b so as to protrude upward. The diameter of the inner diameter portion 2g is larger than the diameter Ds of the screw head Sa. Eggplant.
The cap insertion cylinder 2d is formed with a slit-like engagement groove 2e upward from the lower end surface 2a, and a step 2f is formed at the upper end thereof.
In this embodiment, the engaging grooves 2e are formed at two locations facing each other.

Reference numeral 3 denotes a screw cap formed of a synthetic resin material.
FIG. 3 is a longitudinal sectional view of the screw cap 3.
4 is a top plan view of FIG.
5 is a right side view of FIG. It is.
3a is an annular flange formed at the upper end thereof, and a thin cylindrical portion 3b is formed downward from the annular flange 3a.
The outer diameter of the thin cylindrical portion 3b is formed to be a diameter inserted into the inner diameter portion 2g of the cap insertion cylindrical portion 2d of the second member 2. That is, it is formed with the same diameter or a slightly smaller diameter.
The thin-walled cylinder portion 3b is formed with a locking piece portion 3e formed by a notch groove 3d from the lower end 3c upward. The locking piece 3e has a cantilever shape in which the upper part is fixed and the lower part forms a free end.
Further, a locking projection 3f and a regulation projection 3g are formed on the locking piece 3e.
The locking projection 3f is formed to protrude outward from the outer periphery 3h of the locking piece 3e. In this example, the locking projection 3f has a hemispherical shape.
Further, the restricting protrusion 3g is formed to protrude inward from the inner periphery 3k of the locking piece 3e.
The locking piece 3e including the locking protrusion 3f and the restricting protrusion 3g is formed in two opposing positions, and the inner diameter A of the opposing restricting protrusion 3g is inserted into the screw insertion hole 2c. The diameter of the screw S is smaller than the diameter Ds of the screw head Sa, and is larger than the diameter of a screwdriver (not shown) that is inserted into the bit of the screw S and rotates the screw S.

Next, the screwing of the first member 1 and the second member 2 will be described with reference to FIGS.
First, the lower end surface 2a of the second member 2 is disposed in contact with the upper end surface 1a of the first member 1, and the screw insertion hole 2c of the second member 2 faces the female screw hole 1b of the first member 1. To do.
Secondly, the screw S is disposed in the cap insertion tube portion 2d, and the screw S is disposed and screwed into the female screw hole 1b via the screw insertion hole 2c, whereby the second member 2 is screwed into the first member 1. Screwed on.
Third, the thin cylindrical portion 3b of the screw cap 3 is inserted into the inner diameter portion 2g of the cap insertion cylindrical portion 2d of the second member 2, and the locking projection 3f is inserted into the cap at the initial insertion of the thin cylindrical portion 3b. The locking protrusion 3f is pressed by the inner diameter portion 2g of the cylindrical portion 2d and displaced inward, and the locking projection 3f is in contact with the upper end of the cap insertion cylindrical portion 2d. The engagement protrusion 2f is engaged with the step 2f of the engagement groove 2e.
According to the above, the downward movement of the screw cap 3 is restricted by the annular flange 3a being locked to the upper end of the cap insertion cylinder part 2d, and the upward movement of the screw cap 3 is the step of the engagement groove 2e. The screw cap 3 is fixedly arranged on the second member 2 by being locked by the portion 2f.

Then, in a state where the screw cap 3 is fixedly disposed on the second member 2, if the screw S is urgently generated and the screw S does not move upward, the screw S escapes from the female screw hole 1 b and faces outward. Will not fall off.
This is because when the screw S is Yurumi and the screw S moves upward, the screw head Sa comes into contact with the restricting protrusion 3g that faces and faces the screw head Sa, and further upward movement of the screw S is suppressed. By being done.

On the other hand, the case where the screw S is removed and the second member 2 is removed from the first member 1 will be described. A screwdriver (not shown) is inserted into the bit hole of the screw S through the inner diameter A of the restricting projection 3g of the screw cap 3. In this state, the screw S is screwed to allow the screw S to escape from the female screw hole 1b, whereby the second member 2 can be removed from the first member 1.
In such a removed state, the second member 2 can move upward in synchronization with the screw S. Even when the second member 2 is removed from the first member 1, the screw S is still attached to the screw cap 3. And can be held by the second member 2.

According to the above, the second member 2 is screwed and fixed to the first member 1 with the screw S. In addition, even if Yurumi occurs in the screw S in a state where the second member 2 and the first member 1 are screwed and fixed, the screw cap 3 prevents the screw S from moving in the escape direction. Can be prevented from falling off.
Further, when the second member 2 is removed from the first member 1 by screwing the screw S, the screw S can be rotated to release the screwed state without removing the screw cap 3, and the second member 2 can be removed from the second member 2. The screw S can be held. This eliminates the need for the screw S to be lost during the maintenance work or to dispose the screw S on the second member 2 each time, thereby improving the maintenance workability.
In addition, when the screw S is inserted and arranged in advance with respect to the second member 2 and the screw cap 3 is inserted and arranged in the cap insertion cylinder portion 2d, the second member 2 can be put into a small assembly state without dropping the screw S. The assembly efficiency of the second member 2 with respect to the first member 1 can be improved.

Further, the screw cap 3 is disposed so as to face the screw head Sa and does not mechanically press the restricting projection 3g of the screw cap 3 to increase the diameter. Can be used for a long time.
Moreover, although the screw cap 3 is formed of a synthetic resin material, the material of the second member 2 does not require any limitation.
The second member 2 forms part of the product, and the release of this material limitation is extremely effective in product design.

  Further, since the inner diameter A of the restricting projection 3g of the screw cap 3 only needs to be larger than the outer diameter of the driver that rotates the bit hole of the screw S, the adaptability to screws having different diameters Ds of the screw head Sa is ensured. Can greatly improve.

  Furthermore, the shape of the screw facing surface 3m (the lower side surface of the restricting protrusion 3g in FIG. 3) formed on the restricting protrusion 3g of the screw cap 3 is an inclined surface whose diameter is reduced as it goes upward from below. According to this, when the screw S is urged and the screw S moves upward and collides with the inclined surface, the locking projection 3f is pressed outward, so that the locking projection 3f is engaged. The screw cap 3 is prevented from falling off the groove 2e.

  In the embodiment shown in FIG. 7, an engaging hole 2h is used instead of the engaging groove 2e, and the engaging projection 3f of the screw cap 3 is engaged with the engaging hole 2h.

The longitudinal cross-sectional view which shows one Example of the screw drop-off prevention apparatus which becomes this invention. FIG. 2 is a top plan view of FIG. 1. The longitudinal cross-sectional view of the screw cap used for FIG. FIG. 4 is a top plan view of FIG. 3. The right view of FIG. The right view of FIG. The side view which shows the other Example of the 2nd member. It is a prior art example figure. It is a prior art example figure. It is a prior art example figure. It is a prior art example figure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st member 2 2nd member 2c Screw insertion hole 2d Cap insertion cylinder part 2e Engagement groove 2h Engagement hole 3 Screw cap 3a Annular collar part 3b Thin-walled cylinder part 3e Locking piece part 3f Locking protrusion 3g Restriction protrusion 3m screw facing surface

Claims (3)

A first member having a female screw hole bored toward the upper end surface;
In the two-member screwing device that is arranged on the upper end surface of the first member, and that screwes the second member having the screw insertion hole facing the female screw hole toward the first member with a screw,
The screw cap 3 formed of a synthetic resin material is
An upper annular flange 3a;
A thin-walled cylindrical portion 3b that is continuously provided downward from the annular flange portion 3a and that opens downward;
A plurality of locking pieces 3e formed by cutting upward from the lower end 3c of the thin cylindrical portion 3b;
A locking projection 3f formed to protrude outward from the outer periphery 3h of the locking piece;
A regulating protrusion 3g formed to protrude inward from the inner periphery 3k of the locking piece 3e;
Formed by
On the other hand, the second member is formed with a cap insertion tube portion 2d into which the thin tube portion 3b of the screw cap 3 can be inserted on the outer peripheral side of the screw insertion hole 2c. An engagement groove 2e or an engagement hole 2h in which the engagement protrusion 3f of the screw cap 3 can be engaged and disposed is formed in the tube portion.
The second member is arranged on the upper end surface 1a of the first member 1, and the screw S is screwed into the female screw hole 1b through the screw insertion hole 2c, and then the thin tube portion 3b of the screw cap 3 is connected to the cap insertion tube portion 2d. The engaging projection 3f of the screw cap 3 is inserted into the engaging groove 2e or the engaging hole 2h of the second member 2,
A screw drop-off prevention device, characterized in that the restricting protrusion 3g of the screw cap 3 is disposed facing the screw head 5a.   2. The screw drop prevention device according to claim 1, wherein an inner diameter A of the restricting protrusion is larger than an outer diameter of a driver who rotates the screw. The screw drop prevention device according to claim 1, wherein the screw facing surface 3m formed on the restricting protrusion is an inclined surface having a diameter reduced from below to above.

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