JP2002054617A - Screw provided with thin head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw capable of achieving secure screw driving action even in the case of the screw with a thin head part and a small nominal diameter. SOLUTION: In this screw comprising a head part 2 having an engagement groove 5, and a leg part 4 integrated with that and provided with threads 3, a threadless part 10 having an arc-shaped cross section is formed between a seat surface 7 of the head part 2 and the thread 3 in the leg part 4, a locus circle diameter connecting a top surface 6 of the head part 2 to an outer side wall 8 of the engagement groove 5 is set to be smaller than a root diameter of the thread 3, and the top surface 6 of the head part 2 is formed as a spherical surface of a larger radius. This can thus be used for a product of a relatively thin thickness without deteriorating its natural screw driving function, and screw driving force can correctly be transmitted in driving the screw of the small nominal diameter without rupturing the head part 2 in the middle of screw driving action. Floating of the head part 2 when screw driving work is completed can be eliminated, and fixing force to a subject member to be fastened is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the use of a screw screwed into a workpiece without projecting the head of the screw from the workpiece and impairing the aesthetic appearance of the workpiece, and without causing any problem in the screw-fastening function of the screw. Possible thin-headed screws.

[0002]

2. Description of the Related Art In recent electrical appliances and information equipment products, those having improved performance and relatively small size are often used. Among them, thin products such as thin ones for easy carrying are used. Electronic devices such as electronic notebooks, personal computers, and mobile phones have become widespread. In such a product, the condition is that the weight is as light as possible and the thickness is thin so that it is easy to carry, and a small screw having a nominal diameter of 2 mm or less is inevitably used for a screw for assembling the product. is the current situation. Therefore, in recent years, a screw having a size as small as possible has been developed. However, as shown in FIG. 6, the head 102 of the screw 101 has a cross-shaped engaging groove 105 for engaging with a driver bit. , The shape of the head 102 is still JI
It is a standard head height for the nominal size of the screw set in S (Japanese Industrial Standard). Under such circumstances, recently, it is required that the head is relatively thinner than the standard screw head thickness. In response to this request, a screw 201 as shown in FIG. Fastening member 22
1 is being fixed.

[0003]

However, despite the demand for such a thin product,
The inability to cope with the miniaturization of the product due to the limitation on the miniaturization of the screw has a great influence on future assembling work. To solve this problem, a screw whose head is extremely thin compared to a conventional screw with a small nominal diameter has been considered. Because of the presence of the engagement groove, the engagement groove becomes brittle and the engagement groove reaches the screw leg, so that the material of the leg is thinned or torn, and a sufficient function as a screw is obtained. Absent. In addition, when the screw material is subjected to heat treatment and plating to give the necessary strength to the screw, if the top surface of the head is flat, the volume of the head is small, so that it is difficult to handle each other during a large amount of processing work. Have come into close contact with each other, and the heat treatment and plating are incomplete.

In order to solve this problem, the one shown in FIG. 5 is being used. However, since the head is made thinner than a standard one, an engagement groove formed in this screw is formed. Due to this, a tapered reinforcing portion with a relatively large diameter on the head side is formed between the head and the screw thread, thereby generating a thin portion caused by forming the engagement groove. Has been prevented. By preventing the occurrence of a thin portion with such a configuration, even if a predetermined screwing force is applied to this screw,
Although the breakage of the screw has been resolved, there is a large screwless part in the reinforcement between the screw thread and the head, so this works during screw tightening work, and the screw is slightly removed from the work. Is emerging. In addition, the reinforcing part diameter A
Since the diameter of the thread is larger than the thread diameter, there is a problem that the floating of the screw cannot be prevented and the fixing force is weak unless the prepared hole of the member to be fastened to the work is relatively large so as to receive the hole.

An object of the present invention is to provide a screw which solves such a problem and which can provide a reliable screwing action even with a screw having a small head thickness and a small nominal diameter.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a head 2 having an engaging groove 5 with which a driver bit is engaged, and a leg united with the head 2 and having a thread 3 formed therein. 4, a screwless portion 10 having an arc-shaped cross section is formed between the bearing surface 7 of the head 2 and the thread 3 of the leg 4;
This is achieved by providing a thin-headed screw having a locus circular diameter connecting the outer wall 8 of the engagement groove 5 intersecting with the top surface 6 of the head 2 smaller than the root diameter of the screw thread 3. Further, in addition to this configuration, the above object is also achieved by providing a thin-headed screw in which the top surface 6 of the head 2 has a spherical shape formed with a large radius. Furthermore, in addition to this, the engaging groove 5 is
This can also be achieved by providing a thin-headed screw which is inclined toward the center of the leg 4 as it gets deeper from the top surface 6 to the leg 4.

[0007]

FIG. 1 is a block diagram showing an embodiment of the present invention.
4 through FIG. 1 and 2, 1
Is a screw composed of a head 2 and a leg 4 integral with the head 2 and having a thread 3. The head 2 of the screw 1 has a cross-shaped engaging groove 5 for engaging with a driver bit (not shown) on the center line of the leg 4. 4 has been reached. The head 2 is formed to be relatively thinner than the head 2 of the ordinary screw 1. The thickness of the head 2 is about 1/3 of the nominal diameter of the screw 1 or less. Is set to The top surface 6 of the head 2 has a spherical shape with a relatively large radius, and the outer peripheral edge of the head 2 has a thickness smaller than that of the central portion.

As shown in FIG. 3, the leg 4 at a position close to the seating surface 7 of the head 2, that is, between the seating surface 7 of the head 2 and the thread 3 of the leg 4, A screwless portion 10 having an arcuately large cross section is formed. The position of the screwless portion 10 connected to the head side is determined by the outer diameter of the screw thread 3 formed on the leg portion 4 of the screw 1. It is located slightly outside the center. The threadless portion 10 has a predetermined thickness between the outer wall 8 of the engagement groove 5 and the engagement groove 5 intersecting the top surface 6 of the head 2 to form this thickness. Outside wall 8
Is set to a dimension L smaller than the root diameter of the screw thread 3. The engagement groove 5 is inclined toward the center of the leg 4 as it becomes deeper from the top surface 6 of the head 2 to the leg 4, so that the outer wall 8 of the engagement groove 5 and the threadless portion 10 are formed. Between the screw and the driving force when screwing
It is thick enough to transmit to

On the other hand, the thread 3 is formed below the threadless portion 10 so as to extend to the tip of the leg 4, and on the thread side of the threadless portion 10, the incomplete thread portion 1 of the thread 3 is formed.
One has reached.

[0010] In the operation of screwing into the work 20 using the thin-headed screw 1, as shown in FIG.
The driver bit is engaged with the screw groove of the screw 1 in the screw hole of the work 20 to transmit the screwing force and screw the screw. At this time, the screwing force from the driver bit is transmitted from the threadless portion 10 to the leg 4, and the thread 3 is
With a predetermined screwing force. At this time, work 2
The fastening member 21 fixed to 0 has a pilot hole 22 through which the leg 4 of the screw 1 penetrates. It is sufficient if the inner diameter B of the pilot hole 22 is slightly larger than the outer diameter of the screw thread 3. Thus, the hole diameter A of the conventional member 21 to be fastened can be made smaller, and this hole diameter can be minimized.

When the screw 1 is screwed in after the member 21 to be fastened is aligned with the screw hole of the work 20, the screw thread 3 is screwed into the screw hole of the work 20 and the seat surface of the head 2 is seated. When the member 7 is seated on the member 21 to be fastened, the screwing operation is completed.

[0012]

As is apparent from the above-described embodiments, the present invention has a head 2 having an engaging groove 5 with which a driver bit is engaged, and a leg unit formed integrally with the head 2 and having a thread 3. 4, a screwless portion 10 having an arc-shaped cross section is formed between the seating surface 7 of the head 2 and the screw thread 3 of the leg 4, and is engaged with the top surface 6 of the head 2. Outer wall 8 of mating groove 5
Is smaller than the root diameter of the screw thread 3 and the top surface 6 of the head 2 is formed into a spherical shape with a large radius, and the leg 4 extends from the top surface 6 of the head 2 to the leg 4. Is a thin-headed screw having an engagement groove 5 inclined in the center direction of the product, so that it can be used without impairing the original screwing function as a screw suitable for use in a small and relatively thin product. Even thin products can be assembled using these screws. In addition, since the trajectory circle connecting the outer walls of the engaging grooves reaching the screw leg is smaller than the root diameter of the screw, the screwing force is accurately transmitted when screwing a screw having a small nominal diameter, and the head is screwed during screwing. It is not broken between the part and the leg. Furthermore, when heat treatment and plating are performed to give the necessary strength to the screw, the heads are slightly spherical, so that the heads may adhere to each other during the heat treatment and plating. The surface treatment work can be completely performed without unevenness. Moreover, since there is no large reinforcing portion between the head and the screw thread, there is a specific effect that the lifting of the head at the end of the screwing operation is eliminated and the fixing force of the member to be fastened is improved.

[Brief description of the drawings]

FIG. 1 is a front view of a thin-headed screw showing an embodiment of the present invention.

FIG. 2 is an enlarged bottom view of FIG.

FIG. 3 is an enlarged partial sectional front view showing a main part of the present invention.

FIG. 4 is a sectional view showing a screwed state of the present invention.

FIG. 5 is a sectional view showing a screwed state of a screw before improvement.

FIG. 6 is a sectional view showing a screwed state of a conventional screw.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screw 2 Head 3 Thread 4 Leg 5 Engagement groove 6 Top surface 7 Seat surface 8 Outer side wall 10 Threadless part 11 Incomplete thread part 20 Work 21 Workpiece 22 Workpiece 22 Prepared hole

Claims (3)

[Claims] An engaging groove (5) with which a driver bit engages.
A head (2) formed with a head and a leg (4) integrally formed with the head and forming a thread (3), wherein a head seat (7) and a leg screw are formed. A threadless portion (10) having an arc-shaped cross section is formed between the ridge and the top, and the top surface (6) of the head is formed.
Characterized in that the diameter of the trajectory circle connecting the outer wall (8) of the engagement groove intersecting with the thread is smaller than the root diameter of the thread. 2. The screw with a thin head according to claim 1, wherein the head has a spherical shape whose top surface is formed with a large radius. 3. The screw with a thin head according to claim 1, wherein the engaging groove is inclined toward the center of the leg as it becomes deeper from the top surface of the head to the leg.