JP2579389Y2 - Plastic bolt - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a fastener for chemical or electrical equipment, which requires chemical resistance and electrical insulation, a fastener for a product requiring a decorative appearance, a pure water device, and a semiconductor cleaning device. The present invention relates to a plastic bolt used for a fastening portion that places importance on cleanliness in a device, etc., and a fastening portion of various devices requiring weather resistance.

[0002]

2. Description of the Related Art With the development of engineering plastics, plastic bolts have mechanical strength and heat resistance comparable to metal bolts, as well as chemical resistance and electrical insulation required for chemical and electrical equipment. In addition, products that respond to complex characteristics required in various industrial fields, such as appearance, weather resistance, and metal ion elution prevention properties, have been supplied to the market. Since plastic bolts can be manufactured by molding techniques such as injection molding, metal bolts having a shape that is difficult to manufacture by universal cutting are efficiently produced. For this reason, many plastic bolts in which the effective screw portion is molded to the bolt head seat surface are produced.

[0003]

[Problem to be Solved by the Invention] In the case of a plastic bolt in which an effective screw portion is molded to the bolt head seat surface, the shape of the root of the screw shaft on the bolt head seat surface has a notch effect. In addition, the screw shaft tends to break from the root of the bolt seat, and the allowable tightening force tends to decrease. In metal bolts, it is generally practiced to add a fillet having a circular cross section called an R fillet to the root of the bolt seat surface of the screw shaft to prevent a notch shape effect.

On the other hand, both plastic and metal bolts are often used in combination with spring washers and various other detent components to prevent loosening. In particular, since the tightening force tends to be loose in plastic bolts, anti-rotation parts have been frequently used.

An object of the present invention is to provide a bolt with a detent function for preventing the bolt from being loosened, which tends to occur in a conventional plastic bolt, and to prevent a decrease in strength due to breakage at the root of the bolt head seat surface of the screw shaft. An object of the present invention is to provide a plastic bolt adapted to be used.

[0006]

SUMMARY OF THE INVENTION The present invention for solving the above-mentioned object is to provide a plastic bolt around a root of a screw shaft on a bearing surface of a bolt head and from a bearing surface of a bolt head to a surface of a screw shaft. A sub-seat surface that rises toward the bottom is provided, and a projection shape of the outer peripheral edge of the sub-seat surface onto the bearing surface of the bolt head forms an irregular shape having an arbitrary number of peaks. It is surrounded by a plane that matches the seating surface of the part, and the inside is composed of a surface that is raised more than the seating surface of the bolt head, and where the auxiliary seating surface intersects the screw shaft surface, the auxiliary seating surface is screwed by a curved surface. It is to constitute the fillet that enters the shaft surface.

[0007]

When the plastic bolt is tightened, first, the auxiliary seating surface of the bolt head starts to contact around the bolt hole of the member to be tightened and the tightening surface of the member to be tightened. When the tightening is further advanced, the sub seat surface of the bolt head starts to deform.
That is, the material of the convex portion of the sub seat surface can be pushed out to the concave side by the radial tightening force, and a part of the material is press-fitted into the bolt hole to fill the gap between the bolt hole and the screw shaft. I do. When the bolt is completely tightened, the seat surface of the bolt head directly presses against the surface of the member to be tightened, and the tightening between the bolt hole and the screw shaft is advanced, so that the effect of preventing the bolt from loosening is maximized.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail with reference to the accompanying drawings. A plastic bolt having various head shapes having a flat fastening seat surface is possible, but a small bolt generally called a screw having a button-shaped head is illustrated. The bolt 1 comprises a button-shaped bolt head 2 and a screw shaft 4 as shown in FIG. The bolt head 2 has an operation groove 7 into which a bolt tightening tool is fitted. The operation groove 7 has a hexagonal groove 8 at the center and can be constituted by a minus groove 9 extending from the hexagonal groove 8.

A sub-seat surface 10 having a ridge line 5 that rises from the seat surface 3 toward the screw shaft 4 around the seat surface 3 of the bolt head 2 and the root of the screw shaft 4. There is a fillet 6 that fills a corner that intersects the surface of the screw shaft 4. The auxiliary seating surface 10 and the fillet 6 have an uneven outer peripheral edge formed by eight projections 11 and valleys 12 as shown in FIG. The outer side of the outer peripheral edge falls into the plane of the seating surface 3, and the inner side is constituted by a curved surface around the screw axis center line of the ridge line 5 and a surface that matches the fillet 6.

The operation of the bolt 1 will be described with reference to FIGS. In FIG. 1, the bolt 1 is tightened into a member 20 having a female thread, and tightens the member 30. The member 30 has a bolt hole 31 having an inner diameter slightly larger than the outer diameter of the screw shaft. When the bolt 1 is tightened, first, when the bolt 1 is tightened, one of the curved surfaces ranging from the ridge line 5 to the fillet 6 of the auxiliary seating surface 10 of the bolt is formed. The part contacts the periphery 32 of the entrance of the bolt hole 31.

Further, as the tightening proceeds, the corresponding portions of the sub seating surface 10 and the fillet 6 are pressed by the bolt hole periphery 32 and the tightened surface 33 and start to deform. That is, since the radial tightening force acts, the ridge line and the fillet 5 + 6 of the sub seat surface are provided.
Are deformed and pressed into the bolt holes 31 to fill the bolt holes 31. The ridges and fillets 5 + 6 tighten the screw shaft against the inner surface of the bolt hole, thereby exhibiting a bolt rotation preventing effect. At the same time, the shape of the filling member (5 + 6) maintains a sufficient effect to prevent the notch effect of the screw shaft root. As shown in FIG. 4, the outer end of the sub-seat surface 10 in a state where the bolts are completely tightened is expanded from the original shape to form the bolt holes 3.
Tighten the inner diameter surface of 1 to enhance the detent effect.

In addition to the above-described embodiment, the swelling shape of the auxiliary seating surface, the projection shape to the seating surface of the bolt head, the fillet cross-sectional shape of the screw shaft root, the plastic material, and the like are selected. It goes without saying that the locking effect and the strengthening effect of the bolt can be adjusted. In FIG. 2, the valley 12 of the auxiliary seating surface 10 is in contact with the outer diameter of the screw shaft 4, but this can be separated. As shown in FIG. 5, it is also possible to make the planar projection shape of the auxiliary seating surface into a star shape 14 having an acute angle, or to form a mixture with the uneven shape shown in FIG. 2 of the embodiment. The number of peaks may be arbitrary and is not limited to even or odd numbers. The side surface shape of the sub seating surface can be formed only by the fillet formed by the R fillet, not by combining the ridge line 5 and the fillet 6 shown in FIG. In the embodiment shown in FIG.
2, ie, the outermost end of the top 11 in FIG. 2 coincides with the seating surface 3, but it is also possible to start with a step to give the outermost end of the sub seating surface a thickness. The effective screw is formed up to the joint of the fillet 6 to the surface of the screw shaft.
Depending on the application, a shaft portion that does not have a screw can be provided by being retracted from the joint portion.

[0013]

According to the present invention, it is possible to provide a plastic bolt having an increased strength by preventing stress concentration occurring at the base. In addition, it is possible to shift to small-diameter bolts, and to eliminate the bolt locking parts that are commonly used together with a built-in bolt locking effect, thereby reducing the cost of the fastening member.

[Brief description of the drawings]

FIG. 1 is a side view of a plastic bolt.

FIG. 2 is a plan view of a seat surface of a plastic bolt head.

FIG. 3 is an enlarged side view of a plastic bolt head seat surface and a screw shaft root portion;

FIG. 4 is a plan view of a sub-seat surface of a plastic bolt head after bolt fastening.

FIG. 5 is a plan view of another embodiment of a plastic bolt head sub seating surface.

[Explanation of symbols]

 1. Plastic bolt 2. Bolt head 3. Bolt head seat surface 4. Screw shaft 5. Sub-seat surface ridge line 6. Fillet 7. Tightening tool groove 10. Sub-seat surface 11. Top of sub seating surface 12. Valley of sub seating surface 20, 30, member to be tightened 31, bolt hole 32, around bolt hole 33, surface to be tightened

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16B 35/00 F16B 39/282

Claims (1)

(57) [Scope of request for utility model registration] In a bolt made of plastic, a sub-seat surface protruding from the seat surface of the bolt head toward the surface of the screw shaft is provided around the base of the screw shaft on the seat surface of the bolt head. The projected shape of the outer peripheral edge of the bearing surface onto the bearing surface of the bolt head is an uneven shape with an arbitrary number of peaks, and the outer side of the outer peripheral edge of the sub-bearing surface is surrounded by a plane that matches the bearing surface of the bolt head. , The inner side is composed of a surface raised from the seat surface of the bolt head, and in the part where the sub seat surface intersects the surface of the screw shaft, the sub seat surface forms a fillet that enters the screw shaft surface by a curved surface. Features plastic bolts.