JP2765509B2 - Special screw - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a special screw for industrial use, and more particularly to a special screw which does not cause an electric short circuit even when it comes into contact with a current-carrying 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 fastening object having a female screw formed therein. Is generally formed of a single material. Therefore, when these screws come into contact with an electronic substrate or the like in which a current is conducted, a short circuit phenomenon occurs between circuits.

[0003] In order to solve such inconvenience, there is a type in which the head and the tip of the screw other than the screw portion are coated with an insulating material. This is because the thread portion has a thread groove, and the surface has irregularities, so that the insulating material cannot be appropriately covered.

On the other hand, for the purpose of more reliable electrical insulation of the surface of the screw, Japanese Utility Model Laid-Open Publication No. 63-17731 discloses a 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 a screw head 57 to which a screwdriver is provided and a tip portion 59 of the screw portion are formed by a core of the screw 51. The metal material as 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. For this reason, when such a screw comes into contact with the conductive substrate, it comes into contact with a conductive portion projecting from the surface of the substrate such as an IC foot soldered onto the substrate. As a result, a short circuit occurs between circuits on the substrate.

In a screw for covering a screw portion with an insulating material, a flexible insulating member enters between the contact surfaces of the screw structure portion when the screw portion and the screw hole are fitted. Become. For this reason, when the screw structure is configured with the dimensional tolerance applied to the normal screw and the screw hole, there is an inconvenience that the screw is firmly tightened. Further, in order to form the screw structure in consideration of the thickness of the insulating material, high processing accuracy is required, which causes a disadvantage that the manufacturing cost is increased. Further, when the screw is once fixed to the screw hole and then loosened again, the insulating material coated on the surface of the screw portion is peeled off, exposing the metal material.
For this reason, the screw used once has a disadvantage that the insulating effect is reduced.

[0007] The above disadvantages are particularly problematic in the control devices of office machines and machine tools or in 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 metal screws are accidentally dropped on a circuit board that is energized, a short circuit occurs between electronic circuits. Because it causes. Further, in maintenance and inspection of these devices, work may be performed while the devices are operated, that is, while current is conducted to the circuit board.

[0008]

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

[0009]

In order to achieve the above object, according to the first aspect of the present invention, a special screw is fitted into a head portion to which the tip of a screwdriver is abutted and a screw hole. It has a cylindrical screw portion and a screw hole guide portion formed in the tip region of the screw portion to guide the screw portion into the screw hole. A head insulator is attached around the head, and a barrel-shaped insulator capable of buckling along the longitudinal direction of the screw portion.
Attach an edge, and attach this barrel-shaped insulator to two ring members and
And a wall member disposed between these ring members.
The ring opening of the ring member located on the head side.
The diameter is adapted to be fitted to the flange portion .

The invention according to claim 2 adopts a configuration in which a guide portion insulator is mounted on the guide portion for screw holes, and the other configuration is the same as that of the invention according to claim 1.

Further, the invention according to claim 3 employs a configuration in which the side wall member of the barrel-shaped insulator is divided into a plurality of pieces along the center axis, and the other configuration is the invention according to claim 1 or 2. Is the same as

[0012]

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

When a plurality of members are to be fastened to each other using the special screw, first, a 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 in accordance with the rotation of the screw, but since the barrel-shaped barrel-shaped insulator is attached to the screw portion, the barrel-shaped insulator is brought into contact with a member to be fastened. When the screw is 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 buckles and deforms along the longitudinal direction of the screw portion. Thus, the fastening members are mutually fastened by the special screw.

Furthermore, when the special screw once used for fastening is loosened, the side wall member of the barrel-shaped insulator recovers its original shape and covers the periphery of the screw portion. . For this reason, even if the special screw contacts the electric circuit when performing maintenance or 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 present invention, the guide portion insulator is attached to the screw hole guide portion. Therefore, before the special screw is fastened, the metal portion, which is the basic material of the special screw, is formed of the screw. Not exposed on the surface. For this reason, even if the special screw comes into contact with the energized electric circuit, the screw itself does not short-circuit the electric circuit.

Further, in the invention according to claim 3, the side wall member of the barrel-shaped insulator is divided into a plurality of portions along the longitudinal direction of the screw portion. At this time, according to the screwing of the special screw into the screw hole, the side wall member of the barrel-shaped insulator is deformed along the longitudinal direction of the screw portion. Each side wall member of the barrel-shaped insulator is divided into a plurality of plate-like members having a predetermined width, and is formed such that a central portion in the longitudinal direction projects outward. For this reason, the side wall member of the barrel-shaped insulator bends so as to easily protrude 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 One 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 has a head 1 to which the tip of the screwdriver is abutted.
1 and a cylindrical screw portion 9 fitted 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 mounted around the head 11 of the special screw 1, and the guide insulator 5 is mounted on the screw hole guide. Further, a barrel-shaped insulator 7 formed in a barrel shape is mounted around the screw portion 9.

To explain 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 a screw such as a commercially available round screw. 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 of the screwdriver is provided.

Further, 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 match each other. Here, the head insulator 3 is made of ABS
And the like, and formed integrally with the head 11 of the special screw 1 by injection molding. However, the mounting method is not limited to this. For example, a concave portion having an inner diameter slightly smaller than the outer diameter of the head portion 11 of the special screw 1 is formed on the lower surface of the head insulator 3. The recess may be configured to fit into the head 11 of the special screw 1.

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

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

More specifically, the upper ring member 23 is formed in a disk shape having a diameter substantially equal to the outer diameter of the head 11 of the special screw 1. An upper ring port 24 having a diameter substantially equal to the diameter of the screw portion 9 is provided at the center of the upper ring member 23. The upper ring opening 24 is for inserting the screw portion 9 when the barrel-shaped insulator 7 is mounted on the screw portion 9, and the barrel-shaped insulator 7 falls off from the screw portion 9. Has the function of preventing 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 port 24. Here, the upper ring opening is not limited to the above-described circular shape. For example, as shown in FIG. 3A, a crest diameter larger than the diameter of the screw portion 9 and smaller than the diameter of the screw portion 9 are formed. A star-shaped upper ring member 24a having a diameter may be formed.

Further, below the upper ring member 23, as shown in FIG.
The lower ring member 25 is provided at a predetermined interval. The lower ring member 25 is
And a lower ring opening 26 larger than the diameter of the screw portion 9 is formed at the center thereof. The lower ring opening 26 is sufficiently large so that when the special screw 1 is screwed into the screw hole, no frictional force is generated between the lower ring opening 26 and the surface of the screw portion 9.

A plate-like side wall member 21 is disposed between the upper ring member 23 and the lower ring member 25, and is thereby integrated with each of the ring members 23, 25 to form a barrel-shaped insulator. 7 are configured. This side wall member 21
The whole is divided by a plurality of notches along the longitudinal direction of the screw portion 9. That is, in other words,
The upper end of the plurality of plate-shaped side wall members 21 is the upper ring member 2.
3 and the lower end of the side wall member 21 is engaged with the outer periphery of the lower ring member 25, respectively. Each side wall member 21 is formed with a predetermined fold 27 near the center in the longitudinal direction, 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 is used.
4 will be described with reference to FIGS. 4 to 6.
Shows a case where the barrel-shaped insulator 7 is attached to the screw portion 9 when viewed from the guide portion insulator 5 side. As described above, the barrel-shaped insulators 7 have the screw portions 9 inserted into the upper ring ports 24 provided in the upper ring member 23, and are fixed to each other by frictional force generated therebetween. At the same time, the guide 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 11 of the special screw 1 and the distal end region of the screw portion 9, and the metal as the key material of the screw is exposed on the surface. Not.
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 the present embodiment falls on the electric circuit board 31 which is energized and comes into contact with the energized area 33 raised on the board 31. No short circuit occurs between the circuits. In particular, when disassembling the device during maintenance or inspection work of an electric device or the like, even if the special screw 1 once used is accidentally dropped on the substrate 31 that is being energized, the barrel-shaped insulator 7 retains its own. The original shape is restored by the reaction force. Therefore, even when the special screw 1 is detached from the electric device, the screw portion 9 where the metal material is exposed is always covered by the barrel-shaped insulator 7. As a result, even if the special screw 1 is dropped on the substrate 31 or the like, the metal part of the special screw 1
The short-circuit state is effectively prevented without contacting the protruding portion 33 such as the soldered portion.

The case where the fastening member 35 is fixed with the special screw 1 will be described with reference to FIG.
Is inserted into a screw hole (not shown).
Then, the side wall member 21 of the barrel-shaped insulator 7 is
Of the screw head 11 and the surface of the fastening member 35 as the screwing operation proceeds. Then, the side wall member 21
Is bent toward the outside of the barrel-shaped insulator 7. At the same time, the length of the screw portion 9 of the barrel-shaped insulator 7 in the longitudinal direction is reduced. When the lower surface of the head 11 approaches the surface of the fastening member 35, the side wall member 21 is almost folded in two. For this reason, even with the special screw 1 of this embodiment, it is the same as a normal screw in terms of fixing force and durability, and at the same time, a short circuit of an electric circuit is prevented, and assembly, maintenance, and inspection of an electric device are performed. Etc. become easy.

[0028]

Since the present invention is constructed and functions as described above, according to the first aspect of the present invention, even if the special screw falls onto the energized electric circuit board, each of the insulators can be used. Since it comes into contact with the current-carrying part, there is an excellent effect that a short-circuit phenomenon between the electric circuits is effectively prevented.

Further, in the special screw according to the present invention, since the screw portion is made of a metal material like a normal screw, conduction between the fastening members can be appropriately secured, and at the same time, a strong tightening torque is applied. , Which is an excellent effect. In addition, according to the present invention, since the screw portion is not covered with an insulating material or the like, the dimensional tolerance between the screw portion and the screw hole can be made similar to that of a normal screw structure in manufacturing the screw portion. Can be suppressed.

Further, even when the special screw according to the present invention is once fixed in the screw hole and then loosened and removed again, the barrel-shaped insulator recovers its original shape and covers the screw portion. ,
Even if a special screw is used once, the screw portion is again protected by the barrel-shaped insulator. For this reason, when removing a screw at the time of maintenance inspection work of an electric device etc., even if a screw falls on an electric circuit board, the outstanding effect that a short circuit resulting from a screw is effectively prevented is produced.
That is, the maintenance and inspection of the electric device can be performed while the current is conducted to the circuit board.

According to the second aspect of the present invention, since the guide insulator is also mounted on the screw hole guide portion of the screw portion, even if the tip region of the screw falls on the energized circuit board. No short circuit occurs.

Furthermore, according to the third aspect of the present invention, since the side wall member of the barrel-shaped insulator is divided into a plurality, the side wall member is easily deformed as the screwing operation proceeds. For this reason, a screwing operation can be performed smoothly like a normal screw.

[Brief description of the drawings]

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

FIG. 2 is a view showing a barrel-shaped insulator applied to the special screw disclosed in FIG. 1, FIG. 2 (A) is a top view of the barrel-shaped insulator, and FIG. FIG. 2C shows a front view of the barrel-shaped insulator, and FIG. 2C shows a bottom view of the barrel-shaped insulator.

FIG. 3 is a view showing a modified example of the barrel-shaped insulator disclosed in FIG. 1; FIG. 3 (A) shows a top view of the barrel-shaped insulator; FIG. 3 (B) shows a barrel-shaped insulator. FIG.
(C) shows a bottom view of the barrel-shaped insulator.

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

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

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Special screw 3 Head insulator 5 Guide part insulator 7 Barrel-shaped insulator 9 Screw part 11 Head 21 Side wall member

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16B 35/00 F16B 33/06

Claims (3)

(57) [Claims] 1. A head to which the tip of a screwdriver is abutted,
A special screw, comprising: a cylindrical screw portion fitted into a screw hole; and a screw hole guide portion formed in a distal end region of the screw portion and guiding the screw into the screw hole. A barrel type which can be buckled along the longitudinal direction of the screw portion while attaching the insulator to the portion.
The barrel-shaped insulator is attached, and the barrel-shaped insulator is attached to two ring members and these ring members.
And a wall member disposed between the locking members.
The ring opening of the ring member located on the side is fitted to the screw part
Special screw with a diameter of 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 a central axis thereof.