JP2003247522A - Washer assembled thin head screw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a washer assembled thin head screw with the basic function of a screw that maintains and assembles the washer capable of adhering to the head seat face to the screw while tightening the screw. <P>SOLUTION: The washer-assembled screw comprises a screw consisting of a head 2 and a leg 4 having a screw thread 3 and a washer 20 held between the head seat face 6 and the screw thread 3. The screw 1 has an annular surface of a large diameter at the top head 5, and the tapered reinforcement section 7 between the sheetface 6 and the screw head 3. The washer 20 has a conical guide hole 21 with a large inner diameter of the contact side to the head seat face 6 and a small diameter of the opposite side. The washer is constituted by assembling the washer to the reinforcement section 7 by setting the large side of inner diameter to the seat face side. Therefore, protrusion quantity of the screw is small, and incongruity is not felt even if it is used for the product of this thickness. On the other hand, sufficient tightening power is obtained without damaging the tightening function, because a sufficient cross hole is obtained. Also, cutting off of the neck part, etc., is hard to occur even if large tightening power is applied. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for a screw having a relatively low head height, has a reinforcing portion for sufficiently maintaining the strength of a cross hole in the head, and secures a washer during screwing. And a washer built-in screw capable of fixing a member to be fastened by pressing it against a work.

[0002]

2. Description of the Related Art Recently, electric appliances and information equipment products are often used which have improved performance and are relatively small in size. Among them, for example, the thickness is thin so that they can be easily carried. Electronic devices such as electronic notebooks, notebook computers, and mobile phones are rapidly becoming widespread. Such products must be as light as possible and thin so that they can be easily carried, and the screws for assembling them must have a nominal diameter of 2 mm.
At present, small screws having a size of mm or less are used. Therefore, in recent years, a screw having the smallest possible size has been developed. However, since the screw head has a cross-shaped engagement groove that engages with the driver bit, the shape of the head is still JIS ( It is a standard head height for the nominal size of the screw set by the Japanese Industrial Standard). Under such circumstances, recently, a head whose head is relatively thinner than the head thickness of a standard screw has been required, and the screw 10 as shown in FIG.
1 is being used to fix the fastened member 132 to the work 130.

[0003]

With such a standard screw head height, the head protrudes from the member to be fastened, so that the screw used in the product is conspicuous. Limited product thinness. On the other hand, in the case of a screw whose head height is simply lowered, the cross hole must be maintained as standard in order not to impair the fastening function as the screw, and therefore the depth of the cross hole is the leg part of the screw. It is necessary to reach a depth of up to. In this case, the material in the vicinity of the engagement groove of the leg portion becomes thin, breaks, or the neck of the screw jumps, so that a sufficient function as a screw cannot be obtained. Therefore, it is inevitable that a conical taper-shaped reinforcing portion must be provided between the leg portion and the head seat surface, and a fastening hole with a larger diameter is required so that the reinforcing portion can be inserted in the member to be fastened. Has become. Also, in order to reduce the mounting hole, if you try to reduce the amount of the reinforcement part by incorporating an existing washer, the washer hit the reinforcement part and the screw was not completely screwed in, and the head floated from the fastened member. The so-called screw floating state may occur. On the other hand, if the washer has a hole diameter larger than the outer diameter of the screw in order to solve this problem, the washer comes off from the screw, and the work of assembling the washer is required every time the screw is tightened.

Further, despite the demand for thinner products, there is a limit to the miniaturization of these screws, and the inability to respond to the miniaturization of the products will greatly affect future assembly work. There is a sense of crisis. Also, when the screw material is heat-treated and plated to give the required strength to this screw, if the top surface of the head is flat, this head volume is small, so during a large amount of processing work, mutual Has a problem that the heat treatment and the plating treatment are incomplete.

An object of the present invention is to eliminate such problems and to maintain a basic function of a screw and to install and hold a washer which can be closely attached to a head seat surface when the screw is tightened. To get a thin head screw.

[0006]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a head 2 having an engaging groove 10 with which a driver bit for transmitting a driving force is engaged, an integral part of the head 2, and a screw thread 3. And a seating surface 6 of the head 2
And a washer 20 held between the thread 3 of the leg 4 and a washer 20. The head top surface 5 has an arc surface with a relatively large radius, and the seat surface of the head 2 6 and the screw thread 3 of the leg 4, the screw 1 having a tapered reinforcing portion 7 in which the head side is large and the screw thread side of the leg 4 is small, and the inner diameter of the side in contact with the head seat surface 6 And a washer 20 having a conical guide hole 21 having a large inner diameter and a small inner diameter on the opposite side, and the washer 20 is incorporated into the tapered reinforcing portion 7 with the larger inner diameter side facing the head seat surface. This is accomplished by providing an embedded thin head screw.

In order to achieve this object, the washer 20 having the above construction is formed on the leg 4 close to the reinforcing portion 7 of the screw 1 and has a protrusion 8 having an outer peripheral edge larger than the inner diameter of the washer 20. It may be a thin head screw with a washer that is prevented from coming off. Further, in addition to these configurations, the guide hole 21 of the washer 20 has a screw 1 when combined with the screw 1.
It has a tilt angle B slightly larger than the tilt angle A of the reinforcing portion 7 with respect to the center of the washer, and the reinforcing portion 7 is a thin head screw with a washer that first comes into contact with the side where the inner diameter of the washer 20 is small when screwing. Also achieved by.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIG.
It will be described with reference to FIG. In FIGS. 1 and 2, 1
Is a screw composed of a head 2 and a leg 4 which is integral with the head 2 and has a thread 3 on the outer circumference. Head 2 of this screw 1
The engaging groove 1 in the shape of a cruciform conical hole is engageable with a driver bit (not shown) that transmits a driving force to the center line of the leg portion 4.
0 is formed, and the tip of the depth of the engaging groove 10 reaches the leg portion 4. The outer side wall 11 of the engagement groove 10 has a shape inclined toward the center of the leg 4 as the depth increases from the top surface 5 of the head 2 to the leg 4. The head portion 2 is formed so that its thickness is relatively thinner than the head portion 2 of the ordinary screw 1, and before the engagement groove 10 is formed, that is,
The maximum thickness of the head 2 when the engaging groove 10 is filled with the thickness of the head 2 is set to about 1/3 or less of the nominal diameter of the screw 1. The top surface 5 of the head portion 2 is a spherical arc surface having a relatively large radius, and the outer peripheral edge of the head portion 2 is thinner than the central portion.

As shown in FIG. 1, the head portion 2 of the head 2 is located close to the seat surface 6, that is, the space between the seat surface 6 of the head 2 and the thread 3 of the leg 4, as shown in FIG. A reinforcing portion 7 having a taper shape with a large portion side and a small leg portion side and having no screw thread 3 is formed, and the position of the reinforcing portion 7 connected to the seat surface 6 on the head side is formed on the leg portion 4. From the outer diameter position of the thread 3
It is located outside the center of the. The reinforcing portion 7 has a predetermined thickness with the outer wall 11 of the engaging groove 10, and the reinforcing portion 7 is formed sufficiently larger than the screw thread outer diameter in order to form this thickness. . The angle forming the outer peripheral surface of the reinforcing portion 7 is larger than the angle of the outer side wall 11 forming the engaging groove 10 formed in the head portion 2 of the screw 1, and thus the forging is performed. The molding flow of the material becomes smooth during molding.

On the other hand, a washer 20 is fitted into the reinforcing portion 7, and the washer 20 has a guide hole 21 having a conical inner shape as shown in FIGS. 4 and 5. In this shape, the side of the screw 1 in contact with the seat surface 6 is such that the seat surface side of the reinforcing portion 7 formed at the neck of the screw 1 fits, that is, a diameter slightly larger than the seat surface side diameter of the reinforcing portion 7. The diameter on the opposite side is smaller than the outer diameter of the thread. Further, the inclination angle B of the conical shape with respect to the center line of the screw 1 in the meantime is the inclination angle A of the reinforcing portion 7 of the screw 1.
The angle is set to be slightly larger, so that the small diameter portion of the washer 20 is first contacted and pressed by the inclined surface of the reinforcing portion 7 when tightening the screw.

Further, the screw thread 3 is formed on the lower portion of the reinforcing portion 7 so as to extend to the tip of the leg portion 4.
As shown in FIGS. 2 and 3, has a circular shape so that it can be screwed into a screw hole in which a female screw 31 is formed in advance. In this embodiment, the leg portion 4 has a circular shape. However, the leg portion 4 may have a substantially triangular shape in addition to the circular shape, so that the female screw 3 is formed in the prepared hole (not shown) of the work 30.
In the operation of screwing while forming 1, the smooth screwing operation can be obtained. Further, between the thread 3 of the leg portion 4 and the reinforcing portion 7, there is formed a projecting portion 8 for preventing the washer 20 from coming off when the washer 20 is incorporated. The diameter is smaller than the mountain 3 and larger than the small diameter portion of the washer 20. The protruding portion 8 is formed at a position as close to the reinforcing portion 7 as possible and may be a protrusion along an annular line instead of an annular shape as long as the washer 20 is assembled and held. Such a projecting portion 8 can be roll-formed with the washer 20 incorporated at the same time when the thread is formed.

In the operation of screwing into the work 30 by using the washer-incorporated thin head screw 1, as shown in FIG. 3, the screw 1 is attached to the female screw 31 formed in the prepared hole of the work 30. The screwing force is transmitted to the screw 1 by driving the driver bit in a state where the driver bit is engaged with the engaging groove 10. At this time, the screwing force from the driver bit is transmitted from the reinforcing portion 7 to the leg portion 4, and the screw thread 3 is screwed into the work 30 with a predetermined screwing force.
On the other hand, the fastening member 32 fixed to the work 30 has a mounting hole 33 larger than the thread diameter in advance, and the washer 20 on the seat surface 6 of the head 2 is seated on the surface of the fastening member 32. It is like this.

Then, after the member 32 to be fastened is aligned with the prepared hole of the work 30, the screw 1 is screwed into the prepared hole of the work 30 so that the thread 3 of the leg portion 4 has the female thread 31.
Screwed along. When the screw 1 is screwed in and the washer 20 is seated on the fastened member 32 in this manner, the reinforcing portion 7 comes into contact with and presses the guide hole 21 on the small diameter side of the washer 20. The unit 20 integrally fixes the member 32 to be fastened to the work 30, and the screw tightening work is completed.

FIG. 6 shows a modified example of the washer 20. This is a washer 20 having a small width on the small diameter side. The washer 20 is used in the same manner as described above. However, the same effect can be obtained.

[0015]

As is apparent from the above-described embodiments of the present invention, the head 2 and the screw thread 3 having the engaging groove 10 are formed.
And a seat surface 6 of the head 2
In the washer-incorporating screw consisting of the washer 20 held between the thread 3 and the thread 3, the top surface 5 of the head 2 has an arcuate surface with a relatively large radius, and the seat surface 6 and the thread 3 A screw 1 having a tapered reinforcing portion 7 formed between the head side and the thread side is small, and a conical guide hole 21 having a large inner diameter on the side in contact with the head seat surface 6 and a small inner diameter on the opposite side. Since the washer 20 is a thin head screw with a washer 20 incorporated in the reinforcing portion 7, with the side with the larger inner diameter being the head seat surface side, the head of the screw with respect to the fastened member The amount of protrusion of the part is small and it is not very noticeable when used for a product, and the discomfort of the product is eliminated when used for a thin product.
On the other hand, since a sufficient cross hole can be obtained as compared with a screw whose head height is simply lowered, a sufficient fastening force can be obtained without impairing the fastening function. Further, by using such a washer for the reinforcing portion, even if a large fastening force is applied, the neck jump of the screw is less likely to occur and it is not necessary to provide a large attachment hole in the fastened member.

The washer 20 is formed on the leg portion 4 close to the reinforcing portion 7 of the screw 1 and is prevented from coming off by the projecting portion 8 having an outer peripheral edge slightly larger than the inner diameter of the washer 20. , The washer can be securely incorporated and held without falling off to the reinforcement part, and when tightening the screw,
It is possible to fit the washer to the reinforcing portion accurately.
Therefore, the head of the thin head screw and the washer are integrated when the screw is tightened, and no bending occurs. Moreover, the protrusion may be slightly higher than the inner diameter of the washer, which facilitates the forming process. Further, the guide hole 21 of the washer 20 has the screw 1
Has a tilt angle B that is slightly larger than the tilt angle A of the reinforcing portion 7 with respect to the center of the screw, and when tightening the screw, the reinforcing portion 7 comes into contact with the side of the washer 20 having the smaller inner diameter first. Since the washer is completely pressed by the reinforcing portion of the screw and fixed between the washer and the member to be fastened, the screw floating phenomenon does not occur and the washer does not run idle. Further, in manufacturing the reinforcing portion in the forging process, even if the die is worn and the diameter of the reinforcing portion is increased, the influence on the washer can be minimized.

In addition, by using a screw in which a washer is incorporated in the thin head screw, it is possible to sufficiently cope with the miniaturization of the product, and it is possible to eliminate a sense of crisis in assembling a small product in the future. On the other hand, when the material of the screw and washer is heat-treated and plated to give the required strength, the top surface of the head is not flat, so even if the volume of this material is small, it will be It is possible to obtain a unique effect such as the problem that the head portion of the product adheres and the problems of incomplete heat treatment and plating treatment are solved.

[Brief description of drawings]

FIG. 1 is a cross-sectional front view of a main part of a washer-assembled thin head screw showing an embodiment of the present invention.

FIG. 2 is a bottom view of FIG.

FIG. 3 is a sectional front view showing a usage state of the present invention.

FIG. 4 is an enlarged cross-sectional view of a main part of FIG.

FIG. 5 is a sectional front view of a washer used in the present invention.

FIG. 6 is a sectional front view of another washer used in the present invention.

FIG. 7 is a sectional view showing a conventional example of the present invention.

[Explanation of symbols]

1 screw 2 heads 3 screw threads 4 legs 5 top 6 seat 7 Reinforcement part 8 protrusions 10 Engagement groove 11 Outer wall 20 washers 21 Guide hole 30 work 31 female screw 32 Fastened member 33 mounting holes

Claims (3)

[Claims] 1. A head (2) having an engaging groove (10) for engaging a driver bit for transmitting a driving force, and a leg integrally formed with the head and having a thread (3) formed therein. Division (4)
And a washer built-in screw made up of a screw 1 consisting of and a washer (20) held between the seat surface (6) of the head and the thread of the leg. It has an arc surface with a relatively large radius,
Between the seat surface of the head and the screw thread of the leg, the screw having the taper-shaped reinforcing portion (7) in which the head side is large and the screw thread side of the leg is small, and the screw contacting the head seat surface A conical guide hole (21) with a large inner diameter and a small inner diameter on the opposite side
A washer-incorporating thin head screw, characterized in that the washer is incorporated into the tapered reinforcing portion with the side having a larger inner diameter being the head seat surface side. 2. The washer is formed on the leg portion close to the reinforcing portion of the screw, and is prevented from coming off by a protrusion (8) having an outer peripheral edge larger than the inner diameter of the washer. Thin head screw with washer described. 3. The washer guide hole has an inclination angle B which is slightly larger than the inclination angle A of the reinforcing portion 7 with respect to the center of the screw when combined with the screw, and when tightening the screw, the reinforcing portion has a small washer inner diameter. The washer-incorporating thin head screw according to claim 1 or 2, wherein the thin head screw first contacts the side.