JPH1026119A - Screw part and electric connection structure between metallic parts using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To connect earths without damaging a screw hole by sequentially forming a tapping screw part and an ordinary screw part from a head end part of a shaft part. SOLUTION: Plate materials 20, 30 are connected to each other through a spacer 40, the plate material 20 is previously connected to earths, and the plate material 30 is connected to the earths. A screw hole 20b with a female screw 20c to be screwed on a non-tapping screw 6 of a screw 10 formed on it is provided on the plate material 20, and a through hole 30b larger than an outer shape of a shaft part 4 of the screw 10 is provided on the plate material 30. When the screw 10 is screwed in from the side of the plate material 30, a coating film 20a in the screw hole 20b is peeled by a tapping screw 5, but the plate material 20 is never chipped off. When the screw 10 is iscrewed in further, the screw 6 and the female screw 20c are screwed on each other, a coating film 30a of the plate material 30 is peeled by a projection 3 of a bearing surface 2, and the plate material 30 and the screw 10 are electrically connected to each other. Though a part of the coating film 30a is peeled by the projection 3, as the bearing surface 2 and a surface of the plate material 30 are adhered on each other after fastening, it is never stained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw component and a technique for connecting a metal component to ground using the screw component.

[0002]

2. Description of the Related Art In recent years, many machines whose operation is controlled by a microcomputer are on the market. In such a machine, not only many mechanical parts but also an electric circuit having an IC mounted inside is often complicatedly wired.
In this case, an exterior cover, a frame member,
Metal parts having a relatively large surface area, such as a unit mounting plate, are electrically connected to ground. The reason is that these metal parts act as antennas, which cause the microcomputer to malfunction by picking up noise such as electromagnetic waves entering from outside the machine or electrical noise generated inside the machine. is there. Therefore, in order to prevent the malfunction, the metal parts are connected to each other by using screws to connect these metal parts to the ground. For example, Japanese Utility Model Publication No. 2-20492 (Publication 1). 60-1
There is a technique disclosed in Japanese Patent No. 45561 (known technique 2).

[0003] Known technique 1 discloses a screw in which a projection is integrally provided on the back surface of the screw head. According to this, when the screw is tightened, the projection breaks the varnish layer and cuts into the conductor layer, and the screw is screwed. The conductor layer and the metal component (chassis) are electrically connected to each other, and the ground is taken. Known technique 2 discloses a technique in which a ground connection between a substrate and a metal component (metal body) is fixed using a tapping screw.

[0004]

[0005] By the way, known technology 1
Since the screw portion uses a normal mechanical screw, it cannot be said that the electrical connection between the screw and the metal component is sufficient.
For example, if the surface of the chassis is painted, the paint layer may not make an electrical connection between the screw portion and the metal component. On the other hand, in the prior art 2, since the connection is made by tapping screws, even if the metal part is painted, the paint can be removed, so that the electrical connection between the screw part and the metal part can be reliably performed. it can.

[0005] However, since the fastening with the tapping screw is performed while shaving off the metal parts and the coating, there is a problem that the shaping is performed more than necessary and the screw hole is damaged. The present invention has been made in view of the above circumstances, and has as its object to provide a screw component capable of performing ground connection without damaging a screw hole, and a technique for connecting a metal component to ground using the screw component. It is to provide.

[0006]

In order to achieve the above-mentioned object, a screw component according to the present invention is characterized in that the screw component has a shaft portion on which a screw is formed, and a tapping screw portion and a tapping screw portion are arranged in order from the tip of the shaft portion. That is, a screw portion is formed. Here, the screw component refers to a component such as a bolt or a nut having a part of the screw (JIS screw B0101). The normal screw is defined as a screw other than the self-tapping screw. According to this configuration, when the screw component is screwed into the screw hole in which the screw of the painted metal component is formed, the coating in the screw hole is removed by the tapping screw. After the paint is peeled off, the screwing of the metal part and the screw part is usually completed by the screw. Since the paint has been stripped, the electrical connection between the screw component and the metal component is assured. Further, since the entire shaft portion is formed not at the tapping screw but only at the tip end portion, the screw hole is not cut off more than necessary, so that damage to the screw hole can be prevented.

Further, by providing a projection on the seating surface of the head, the projection can remove the coating on the surface of the metal component. Thereby, the electrical connection between the screw component and the metal component is assured. In connecting the two metal parts to the ground, the two parts are connected via the screw formed on the screw part and the bearing surface. If the tip of the shaft is formed in a tapered shape and a tapping screw is formed in the tapered portion, only the coating can be peeled off without cutting the metal parts. Further, making the pitch of the tapping screw portion equal to that of the normal screw portion is particularly useful when the screw hole is not crushed by the tapping screw and both attaching and detaching of a metal part are required. For example, it is useful when fastening an exterior cover.

Further, by setting the external color of the screw component to a green color different from the normally used external color, the grounding of the metal component can be confirmed by the external appearance of the screw component. The appearance process may be performed on the entire screw part, or only the head that appears outside after fastening the screw part may be green. In the UL (Underwriters Laboratories: American Insurer Safety Laboratory) standard, the ground connection is green and corresponds to this. The metal parts connected to the ground and the metal parts to be grounded are electrically connected by using the above screw parts. Other features and advantages of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0009]

1 shows the shape of a screw 10 according to the present invention. The screw 10 is roughly divided into a head 1 and a shaft 4
Consists of One projection 3 is formed on the bearing surface 2 of the head 1. The projection 3 has a substantially conical shape. Shaft 4
Are formed with a tapping screw 5, a non-tapping screw 6 (normal screw), and an incomplete screw portion 7 in this order from the tip side along the axis. The non-tapping screws 6 are, for example, metric coarse screws, unified coarse screws, metric fine screws, unified fine screws, and the like. Shaft 4
A tapered portion 8 is formed at the tip of the tapered portion, and a tapping screw 5 is formed in the tapered portion 8. In addition, a concave portion 9 is formed in the tapered portion 8 to store the shaved coating debris so as not to be caught by the non-tapping screw. The pitch of the tapping screw 5 and the pitch of the non-tapping screw 6 are the same. The screw portions 5 and 6 of the screw 10 are manufactured by rolling, and the head 1 is manufactured by forging. Also, screw 10
Is surface-treated so that its appearance color is green. By finishing the color different from the color normally used, the screw 10
Can be visually recognized for ground connection.

Next, a method of electrically connecting two metal parts using the screw 10 shown in FIG. 1 will be described. In FIG. 2, it is assumed that the plate member 20 and the plate member 30 are connected via a spacer 40. The plate member 20 is already connected to the ground, and a procedure for connecting the plate member 30 to the ground will be described.
Paint films 20a, 30a are formed on the plate members 20, 30, respectively. A screw hole 20b in which a female screw 20c screwed with the non-tapping screw 6 of the screw 10 is formed in the plate member 20.
Is provided. The plate member 30 is provided with a through hole 30b whose size is larger than the outer shape of the shaft portion 4 of the screw 10 so that the screw 10 can be inserted smoothly without resistance.

The screw 10 is attached to the plate 2 using an air driver.
FIG. 3 shows a state where the coupling of 0 and 30 is completed. The coating film in the screw hole 20b of the plate 20 is peeled off by the portion of the tapping screw 5. The coating film does not need to be completely stripped, but may be stripped even partially. Further, since the tapping screw 5 is formed only in the tapered portion 8, the coating film is almost completely removed by the tapping screw 5, and the plate material 20 is hardly removed.

On the other hand, the coating film of the plate 30 is peeled off by the projections 3 on the seating surface 2. Thereby, the electrical connection between the plate member 30 and the screw 10 is established. As described above, the plate member 20 and the plate member 30 are electrically and mechanically connected via the screw 10. The coating film of the plate 30 is partially peeled off by the projections 3 of the screw 10, but does not rust because the seating surface 2 and the surface of the plate 30 are in close contact with each other in the completed state of the screw 10.

To summarize the advantages of using the screw 10 according to the present embodiment, since the structure in which the screw 10 is used to connect to the ground is used, the original functions of connecting, fixing, and removing parts with the screw 10 are exhibited. Meanwhile, the parts can be dropped to the ground. Since the manufacture of the screw 10 is performed by rolling or forging, the cost of parts does not increase, and the assembly cost of the screw 10 is the same as in the past. In addition, since the coating is peeled off by the projections 3 of the screw 10 and the tapping screw 5, masking is performed when the plate materials 20, 30 are coated, or the coating is intentionally cut off before the fastening of the screw 10 after the coating process. Disappears.

Another embodiment will be briefly described. In the present embodiment, the protrusions 3 are provided at one place, but may be provided at two or more places. The manufacture of the screw 10 may be based on cutting instead of rolling or forging. The metal parts to be connected are not limited to the plate members 20 and 30, and do not depend on what manufacturing method such as die casting or casting is used. The external color of the screw 10 is not green and may be another color.

[Brief description of the drawings]

FIG. 1 is a view showing a shape of a screw;

FIG. 2 is a diagram showing a metal part before being joined by screws.

FIG. 3 is a view showing a state in which the connection by screws is completed.

[Explanation of symbols]

 Reference Signs List 1 head 2 seating surface 3 protrusion 4 shaft 5 tapping screw 6 non-tapping screw (normal screw) 8 taper 10 screw

Claims (6)

[Claims] 1. A screw component having a shaft portion on which a screw is formed, wherein a tapping screw portion and a normal screw portion are formed in order from the tip of the shaft portion. 2. The screw component according to claim 1, wherein a projection is provided on a bearing surface of the head. 3. The screw component according to claim 1, wherein a tip portion of the shaft portion is formed in a tapered shape, and the tapping screw portion is formed in the tapered portion. 4. The screw pitch of the self-tapping screw portion and the screw pitch of the normal screw portion are the same.
3. The screw part according to any one of 3. 5. The screw component according to claim 1, wherein at least the head has a green exterior color. 6. A metal part connected to the ground and a metal part to be grounded are electrically connected using the screw part according to any one of claims 1 to 5. Electrical connection structure between metal parts.