JPH08284934A - Special screw - Google Patents

Abstract

PURPOSE: To provide a special screw which does not short-circuit electronic circuits with each other even if it falls onto a current-carrying substrate. CONSTITUTION: A special screw 1 is equipped with a head 11, on which the tip of a driver abuts, a cylindrical thread part 9, which engages with a screw hole, and a guide part for a screw hole which guides the thread part 9 in the screw hole, being made in the tip area of this thread part 9. And, a head insulator 3 is installed around the head 11, and a barrel-shaped insulator 7 is installed in the screw hole 9, and the sidewall member 21 of this barrel-shaped insulator 7 is constituted so that it may be transformed in longitudinal direction of the screw part 9. Moreover, the guide insulator 5 is installed at the guide part for a screw hole. Furthermore, the sidewall member 21 of the barrel-shaped insulator 7 is divided into plural along the center axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a special industrial screw, and more particularly to a special screw which does not cause an electrical short circuit even when it comes into contact with an energized electric circuit.

[0002]

2. Description of the Related Art A screw is used to fasten an object to be fastened having a through hole larger than the outer shape of the screw to a fastened object having a female screw. Usually, the head of the screw and the entire screw portion are made of metal. It is generally formed by a single material of. For this reason, when these screws come into contact with an electronic board or the like in which a current is conducting, a short circuit phenomenon occurs between the circuits.

In order to improve such inconvenience, there is one in which only the head portion and the tip portion of the screw other than the screw portion are covered with an insulating material. This is because the threaded portion is cut in the threaded portion and the surface is uneven, so that the insulating material cannot be properly covered.

On the other hand, for the purpose of more reliable electrical insulation of the surface of the screw, Japanese Utility Model Laid-Open No. 63-177311 discloses the screw portion 53 covered with an insulator 55 (see FIG. 7). . That is, the surface of the cylindrical screw portion 3 is covered with a flexible insulating resin material 55, and the screw head 57 and the tip portion 59 of the screw portion on which the screwdriver is installed are the core of the screw 51. The metal material, which is the material, is exposed as it is.

[0005]

However, in the above conventional example, the following inconveniences have occurred. That is, in a screw in which only the head of the screw and the tip of the screw are covered with an insulating material, the screw portion occupying most of the entire length of the screw is exposed as a metal material. Therefore, when such a screw comes into contact with the conductive board, the screw comes into contact with a conductive portion protruding from the surface of the board such as a foot of an IC soldered on the board. This causes a disadvantage that short circuits are caused between the circuits on the substrate.

Further, in a screw whose thread portion is covered with an insulating material, when the thread portion and the screw hole are fitted together, a flexible insulating member is inserted between the contact surfaces of these thread structure portions. Become. Therefore, if the screw structure is configured with the dimensional tolerance applied to a normal screw and a screw hole, there arises a problem that the tightening of the screw becomes hard. Further, in order to construct the screw structure in consideration of the thickness of the insulating material, high processing accuracy is required, which causes an inconvenience of increasing manufacturing cost. Furthermore, when the screw is once fixed in the screw hole and then loosened again, the insulating material coated on the surface of the screw portion is peeled off, and the metal material is exposed.
For this reason, the screw once used has a disadvantage that the insulating effect is lowered.

The above-mentioned inconvenience is particularly problematic in control devices for office machines and machine tools or other electronic devices. That is, in these devices, a large number of screws are used to attach components to the chassis or frame, and if a metal screw is accidentally dropped on a live circuit board, a short circuit may occur between electronic circuits. Because it causes. Further, maintenance and inspection of these devices may be performed while the devices are operating, that is, while the current is conducted to the circuit board.

[0008]

It is an object of the present invention to improve the disadvantages of the above-mentioned conventional examples, and in particular, a special screw which does not cause a short circuit between electronic circuits even when dropped on a board which is energized. The purpose is to provide.

[0009]

In order to achieve the above-mentioned object, in the invention according to claim 1, a special screw is fitted in a head portion to which a tip end of a screwdriver abuts, and a screw hole. A cylindrical screw portion and a screw hole guide portion that is formed in a tip region of the screw portion and guides the screw portion into the screw hole are provided. Then, the head insulator is attached around the head, and the barrel-shaped insulator formed in a barrel shape is attached to the screw portion, and the side wall member of the barrel-shaped insulator is attached in the longitudinal direction of the screw portion. It has a structure that allows it to be deformed along.

The invention according to claim 2 adopts a structure in which a guide part insulator is attached to the screw hole guide part, and the other structures are the same as the invention according to claim 1.

Further, the invention according to claim 3 adopts a structure in which the side wall member of the barrel-shaped insulator is divided into a plurality of parts along the central axis thereof, and the other structure is the invention according to claim 1 or 2. Is the same as.

[0012]

According to the first aspect of the invention, the head insulator is mounted around the head of the screw, and the barrel-shaped insulator is mounted on the screw portion, and the side wall member of the barrel-shaped insulator is It is configured to be deformable along the longitudinal direction of the screw part. For this reason, even if the special screw comes into contact with an electric circuit that is energized, a head insulator is provided at the conductive portion of the electric circuit, and a barrel-shaped insulator mounted around the screw portion is used. The side wall members make contact. As a result, even if the special screw falls on the electric circuit, the short circuit does not occur.

Further, when the plural members are fastened to each other by using the special screw, first, the screw hole guide portion is inserted into the screw hole, and the screw portion and the screw hole are provided. Then, the special screw is screwed into the screw hole using a screwdriver. Then, the screw is gradually screwed according to the rotation of the screw, but since the barrel-shaped barrel-shaped insulator is attached to the screw portion, the barrel-shaped insulator abuts the member to be fastened. Then, when further screwed, the side wall member of the barrel-shaped insulator is sandwiched between the lower surface of the head of the special screw and the surface of the fastening member, and is deformed along the longitudinal direction of the screw portion. As a result, the fastening members are fastened to each other by the special screw.

Further, when the special screw once used for fastening is loosened, the side wall member of the barrel-shaped insulator restores its original shape and covers the periphery of the screw portion. . Therefore, even if the special screw comes into contact with the electric circuit when performing maintenance and inspection of a device or the like to which the electric circuit is mounted, a short circuit does not occur.

According to the second aspect of the invention, since the guide portion insulator is attached to the screw hole guide portion, before the special screw is fastened, the metal portion which is the basic material of the special screw is the screw. Not exposed on the surface. Therefore, even if the special screw comes into contact with the electric circuit being energized, the screw itself does not short-circuit the electric circuit.

Further, according to the third aspect of the invention, the side wall member of the barrel-shaped insulator is divided into a plurality of pieces along the longitudinal direction of the screw portion. At this time, the side wall member of the barrel-shaped insulator is deformed along the longitudinal direction of the threaded portion according to the screwing of the special screw into the screw hole. Each side wall member of the barrel-shaped insulator is divided into a plurality of plate-shaped members having a predetermined width, and the central portion in the longitudinal direction thereof is formed so as to project outward. Therefore, the side wall member of the barrel-shaped insulator is easily bent so as to project outward in the radial direction. Further, when tightened, each side wall member of the barrel-shaped insulator is completely bent, and the special screw is securely fastened to the fastening member.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. First, FIG. 1 shows a special screw 1 according to the present invention. This special screw 1 is a head 1 with which the tip of a screwdriver is brought into contact.
1 and a cylindrical screw portion 9 that fits into a screw hole (not shown)
And a screw hole guide portion (not shown) formed in the tip region of the screw portion 9 to guide the screw portion 9 into the screw hole. The head insulator 3 is attached around the head 11 of the special screw 1, and the guide portion insulator 5 is attached to the screw hole guide portion. Further, a barrel-shaped insulator 7 formed in a barrel shape is mounted around the screw portion 9.

Explaining each of these components in detail, the basic structure of the screw used for the special screw 1 is formed according to the same standard as that of a commercially available round machine screw or the like. A cross-shaped driver groove 13 is formed on the upper surface of the head 11 of the special screw 1 so that the tip end of the screwdriver is abutted.

In addition, around the head 11 of the special screw 1,
As shown in FIG. 1, a head insulator 3 having a substantially truncated cone shape
Is mounted so as to cover the head 11 of the special screw 1 from above. A cross-shaped through hole 3a is formed at the center of the upper surface of the head insulator 3, and the cross-shaped through hole 3a and the above-described driver groove 13 are aligned with each other. Here, the head insulator 3 is ABS.
A plastic material such as is used and is formed integrally with the head portion 11 of the special screw 1 by injection molding. However, the mounting method is not limited to this, and for example, a concave portion having an inner diameter slightly smaller than the outer diameter of the head 11 of the special screw 1 is formed on the lower surface of the head insulator 3. You may comprise so that a recessed part may be fitted in the head part 11 of the special screw 1.

Further, in the tip end region of the screw portion 9, as shown in FIG.
As shown in (B), the guide part insulator 5 is attached. The guide portion insulator 5 has a substantially cylindrical shape,
The outer diameter is configured to be substantially the same as the diameter of the valley of the screw portion 9. However, the diameter may be smaller than the root diameter. Further, the guide portion insulator 5 has a tip end portion formed into a spherical shape so that the special screw 1 can be appropriately guided into the screw hole. Here, the guide part insulator 5 is made of a plastic material such as ABS and is formed integrally with the screw hole guide part of the special screw 1 by injection molding as shown in FIG. 1 (B). There is. However, the manufacturing method is not limited to injection molding, and a predetermined convex portion is formed on the tip end of the special screw 1 and a concave portion is formed on the guide portion insulator 5, and these are fitted to each other. You may do it.

As shown in FIG. 2, the barrel-shaped insulator 7 has an annular upper ring member 23 and a lower ring member 25.
And the side wall member 21 disposed between the ring members 23 and 25.

Explaining these in more detail, the above-mentioned upper ring member 23 is formed in a disk shape having a diameter substantially equal to the outer diameter of the head portion 11 of the special screw 1. An upper ring opening 24 having a diameter substantially equal to the diameter of the threaded portion 9 is provided at the center of the upper ring member 23. The upper ring port 24 is for inserting the barrel-shaped insulator 7 when the barrel-shaped insulator 7 is attached to the screw portion 9, and the barrel-shaped insulator 7 is detached from the screw portion 9. It has a function to prevent That is, the barrel-shaped insulator 7 is fixed to the screw portion 9 by the frictional force generated between the screw portion 9 and the inner wall of the upper ring opening 24. Here, the upper ring port is not limited to the above-mentioned circular shape, and for example, as shown in FIG. 3 (A), the root diameter is larger than the diameter of the screw portion 9 and smaller than the diameter of the screw portion 9. A star-shaped upper ring member 24a having a diameter may be formed.

Below the upper ring member 23, as shown in FIG. 2C, in parallel with the upper ring member 23,
Further, the lower ring member 25 is arranged at a predetermined interval. The lower ring member 25 is the upper ring member 23.
And a lower ring port 26 having a diameter larger than the diameter of the threaded portion 9 is formed at the center thereof. The lower ring mouth 26 has a sufficient size so that when the special screw 1 is screwed into the screw hole, no frictional force is generated between the lower ring mouth 26 and the surface of the screw portion 9.

Further, a plate-shaped side wall member 21 is disposed between the upper ring member 23 and the lower ring member 25, whereby the barrel-shaped insulator is integrated with each of the ring members 23 and 25. 7 are configured. This side wall member 21
Is entirely divided by a plurality of notches along the longitudinal direction of the threaded portion 9. That is, in other words,
The upper ends of the plurality of plate-shaped side wall members 21 are the upper ring member 2
3, the lower end portion of the side wall member 21 is engaged with the outer peripheral portion of the lower ring member 25, respectively. Each side wall member 21 has a predetermined fold line 27 formed in the vicinity of the central portion in the longitudinal direction thereof, and is bent outward of the barrel-shaped insulator 7. Here, the side wall member 21 of this embodiment is manufactured by injection molding a plastic material such as nylon. However, a rubber plate member or the like may be used as long as it is an insulating material and has a certain elasticity.

Next, the special screw 1 constructed as described above
4 will be described with reference to FIGS. 4 to 6.
Shows the case where the barrel-shaped insulator 7 is attached to the screw portion 9 as viewed from the guide portion insulator 5 side. As described above, the barrel-shaped insulator 7 has the screw portion 9 inserted into the upper ring opening 24 provided in the upper ring member 23, and is fixed to each other by the frictional force generated between them. At the same time, the guide portion insulator 5 is inserted into the lower ring opening 26 provided in the lower ring member 25, and the barrel-shaped insulator 7 is attached to the screw portion 9 as shown in FIG. . According to this, the head insulator 3 and the guide insulator 5 are attached to the head region 11 of the special screw 1 and the tip end region of the screw portion 9, and the metal as the basic material of the screw is exposed on the surface. Not not.
Further, the surface of the screw portion 9 is also covered with the barrel-shaped insulator 7 described above.

Therefore, as shown in FIG. 5, even if the special screw 1 according to this embodiment falls on the electric circuit board 31 which is being energized and comes into contact with the energizing portion area 33 which is raised on the board 31. , No short circuit will occur between the circuits. In particular, in the maintenance and inspection work of electric devices and the like, even when the special screw 1 that has been used once is accidentally dropped onto the energized substrate 31 when disassembling the device, the barrel-shaped insulator 7 can The original shape is restored by the reaction force. Therefore, even when the special screw 1 is removed from the electric device, the screw portion 9 where the metal material is exposed is always covered with the barrel-shaped insulator 7. As a result, even if the special screw 1 is dropped on the board 31 or the like, the metal portion of the special screw 1 is still on the electric circuit board 31.
The short-circuit state is effectively prevented without coming into contact with the protruding portion 33 such as the soldering portion.

Further, the case of fixing the fastening member 35 with the special screw 1 will be described with reference to FIG.
The guide portion insulator 5 is inserted into a screw hole (not shown).
Then, the side wall member 21 of the barrel-shaped insulator 7 has the special screw 1
As the screwing operation proceeds, the screw head 11 is sandwiched between the lower surface of the screw head 11 and the surface of the fastening member 35. Then, the side wall member 21
The fold line portion 27 near the center of the bends toward the outside of the barrel-shaped insulator 7. At the same time, the length of the threaded portion 9 of the barrel-shaped insulator 7 in the longitudinal direction is reduced. Then, when the lower surface of the head portion 11 approaches the surface of the fastening member 35, the side wall member 21 is almost folded in two. Therefore, even the special screw 1 of the present embodiment is similar to the ordinary screw in respect of fixing force and durability, and at the same time, short circuit of the electric circuit is prevented, and assembly, maintenance and inspection of the electric device are performed. Etc. becomes easy.

[0028]

Since the present invention is constructed and functions as described above, according to the invention of claim 1, even when the special screw is dropped on the electric circuit board which is being energized, each insulator is Since it comes into contact with the current-carrying portion, there is an excellent effect that a short circuit phenomenon between the electric circuits is effectively prevented.

In addition, since the screw portion of the special screw according to the present invention is made of a metal material like a normal screw, it is possible to properly secure the conduction between the fastening members and at the same time, to secure a strong tightening torque. It also has the excellent effect of being able to deal with. In addition, in the present invention, since the screw portion is not a structure in which an insulating material or the like is covered, the dimensional tolerance of the screw portion and the screw hole can be the same as that of a normal screw structure when manufacturing the screw portion, so that the manufacturing cost is reduced. Can be suppressed.

Further, in the special screw according to the present invention, even when it is once fixed in the screw hole and then loosened and removed again, the barrel-shaped insulator recovers the original shape and covers the screw portion. ,
Even if the special screw is used once, the screw part will be protected again by the barrel-shaped insulator. Therefore, when the screw is removed for maintenance and inspection work of the electric device or the like, even if the screw falls on the electric circuit board, a short circuit due to the screw is effectively prevented, which is an excellent effect.
That is, the maintenance and inspection work of the electric device can be performed while the electric current is conducted to the circuit board.

Further, according to the second aspect of the invention, since the guide portion insulator is also attached to the screw hole guide portion of the screw portion, even if the tip end region of the screw falls on the energized circuit board. , No short circuit will occur.

Further, according to the third aspect of the invention, since the side wall member of the barrel-shaped insulator is divided into a plurality of pieces, the side wall member is easily deformed as the screwing operation progresses. Therefore, the screwing operation can be performed smoothly like a normal screw.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG.
Shows a top view of the special screw, and FIG. 1 (B) shows a front view of FIG. 1 (A).

2A and 2B are diagrams showing a barrel-shaped insulator applied to the special screw disclosed in FIG. 1, FIG. 2A is a top view of the barrel-shaped insulator, and FIG. A front view of the barrel-shaped insulator is shown, and FIG. 2C is a bottom view of the barrel-shaped insulator.

3A and 3B are views showing a modified example of the barrel-shaped insulator disclosed in FIG. 1, FIG. 3A is a top view of the barrel-shaped insulator, and FIG. 3B is a barrel-shaped insulator. FIG. 3 shows a front view of the insulation material.
(C) shows a bottom view of the barrel-shaped insulator.

FIG. 4 is a perspective view of the special screw disclosed in FIG. 1 viewed from the screw hole guide portion side.

FIG. 5 is an explanatory diagram showing a state in which the special screw disclosed in FIG. 1 is in contact with the electric circuit board.

FIG. 6 is a perspective view illustrating a state in which the special screw disclosed in FIG. 1 is fixed in a screw hole.

FIG. 7 is a diagram showing a structure of a screw according to a conventional example.
FIG. 7A shows a top view of the screw, and FIG. 7B shows a front view of the screw.

[Explanation of symbols]

 1 Special Screw 3 Head Insulator 5 Guide Insulator 7 Barrel Insulator 9 Screw Part 11 Head 21 Sidewall Member

Claims (3)

[Claims] 1. A head with which the tip of a screwdriver abuts,
A special screw including a cylindrical screw part that fits into a screw hole and a screw hole guide part that is formed in a tip end region of the screw part and guides the screw to the screw hole. The barrel-shaped insulator formed in a barrel shape is mounted on the screw portion, and the side wall member of the barrel-shaped insulator is deformable along the longitudinal direction of the screw portion. Special screw that is characterized. 2. The special screw according to claim 1, wherein a guide portion insulator is attached to the screw hole guide portion. 3. The special screw according to claim 1, wherein the side wall member of the barrel-shaped insulator is divided into a plurality of pieces along the central axis thereof.