JP2003139116A - Cross recessed screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cross recessed screw having a driving recess which is easily tightened to a screw torque set beforehand. SOLUTION: Since this cross recessed screw has a fitting part 14 composing a driving recess 10 with which a screwdriver bit 20 engages and composed of inclined surfaces whose opposing distance b reduces as it goes deeper between engagement grooves 11 adjacent to each other formed, is provided with an undercut part 16 removing material to maintain a parallel surface 17 in parallel with an axial line on the fitting part 14, and has the fitting part 14 composed of the inclined surface left above and beneath the undercut part 16 to engage with a connection part 22 of the screwdriver bit 20, come-out phenomena do not occur often after completion of screwing even if the screw is screwed by using the screwdriver bit. Consequently, a screw fastening torque set beforehand is accurately obtained. Variation in fastening torque is eliminated in an automatic assembly line to reduce occurrence of product defect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prevents a driver bit from slipping up from a driving hole of a screw when driven by a screwdriver and is capable of biting in fitting the driver bit into the driving hole. Regarding screws with holes.

[0002]

2. Description of the Related Art Conventionally, when a screw is tightened or loosened, a driving hole having a cross-shaped engaging groove with which a driver bit is engaged is generally formed in a head on which the driving force acts. By engaging the driving blade of the driver bit with the driving hole, the driving force of the driver bit is transmitted to the screw to tighten the screw on the work. In such a screw tightening operation, a screw 101 having a drive hole 110 as shown in FIG. 7 is generally adopted, and these screws are provided between the engagement groove 111 and the engagement groove 111, which have a cross shape. They are connected by a fitting portion 114 formed of a surface that connects the engagement surfaces of the engagement groove 111. The fitting portion 114 is generally formed in a triangular shape in cross section having a ridge line 115 inclined at equal division positions between the engagement grooves 111, and faces each other with the center line of these screws interposed therebetween. The distance b between the fitting portions 114 increases as it reaches the upper surface of the head 102. The portion is set so as to bite into the connecting portion 122 of the driver bit 120.

On the other hand, in this way, as shown in FIG.
When a rotational driving force for rotating the screw 101 is applied to the driver bit 120, the screw 101 biting into the driver bit 120 receives the rotational force from the engaging blades 121 of the driver bit 120 to the slope of the engaging groove 111 of the screw 101. Under the present circumstances, the screw 101 is transmitted to the engaged surface and the screw 101 is rotated together, and the screw 101 is screwed into a work (not shown).

[0004]

However, a commonly used screwdriver bit for driving a screw is designed so that the engaging blade of the screwdriver bit fits easily into the engaging groove of the screw. It is usually formed to differ from the groove by an angle α, and the tip of the engaging blade is usually a slightly thin blade shape. To improve the biting property between the screw and the driver bit, the interval b of the fitting portion Is specified by the standard, but a so-called cam-out phenomenon in which the engaging blades of the driver bit come out of the drive hole of the screw often occurs when the screw tightening to the work is completed, and a sufficient screw tightening torque is not obtained.
Further, in the automatic assembly work line, the torque is controlled so that the screw tightening torque is always constant, but the screw tightening torque still varies. Furthermore, in order to prevent this come-out phenomenon, thrust must be applied to the driver bit so as to face it, and this thrust causes distortion in the work. Moreover, since the tip of the engaging blade of the driver bit hardly contacts the engaging groove, there are various problems such as insufficient screw tightening torque being obtained.

An object of the present invention is to solve the above problems and to provide a screw having a cross hole having a driving hole, which enables a preset screw tightening torque to be easily obtained.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a drive hole 10 having a cross hole shape with which a driver bit 20 having a cross-shaped engaging blade 21 and a base portion of the base of the engaging blade 21 is engaged. In a screw having a cross hole, which is composed of a formed head portion 2 and a leg portion 4 which is integrated with the head portion 2 and has a thread 3 formed therein, the drive hole 10 is formed and the engaging grooves 11 adjacent to each other are formed. The fitting portion 14 is formed by an inclined surface in which the facing distance b becomes closer as the connecting portion 22 between the engaging blades 21 of the driver bit 20 becomes deeper to fit, and the fitting portion 14 is formed. The relief portion 16 in which the meat is removed so that the inclined surface 14 has a parallel surface 17 parallel to the axis.
It is achieved by providing a cross-shaped screw having the fitting portion 14 formed of the inclined surface above and below the escape portion 16 so as to bite into the connection portion 22 of the driver bit 20 above and below the escape portion 16. Further, the above object can also be achieved in this configuration by forming the escape portion 16 as a screw having a cross hole whose bottom surface is a plane perpendicular to the axis. Furthermore,
In addition to such a configuration, the height of the fitting portion 14 located below the relief portion 16 is lower than that of the fitting portion 14 located above, so that the object can be achieved more reliably.

[0007]

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 comprising a head 2 and a leg 4 which is integral with the head 2 and has a thread 3. A head 2 of the screw 1 is formed with a + -shaped drive hole 10 which engages with a driver bit 20 on the center line of the leg 4, and the tip of the drive hole 10 reaches near the leg 4. There is. The bottom surface 12 of the engagement groove 11 forming the + -shaped drive hole 10 formed in the head portion 2 becomes deeper toward the center. Both side surfaces 13 of the engaging groove 11 are inclined so as to slightly expand from the bottom surface 12 to reach the surface of the head portion 2. By engaging with the engaging blades 21 of the driver bit 20, the screw 1 is not attached to the screw 1. The driving force for tightening or loosening is transmitted.

A fitting portion 14 is formed between the engaging grooves 11 which constitute the driving hole 10 and are adjacent to each other. The fitting portion 14 is formed with a screw 1 as the driving hole 10 becomes deeper. The slope is inclined toward the center line of. The inclined surface has a ridge line 15 at a position facing each other across the center line of the screw 1 and has a triangular cross-section, and projects toward the center line side of the screw 1, and the ridge line 15 of the facing fitting portion 14 faces the ridge line 15.
The distance b of is slightly widened as it reaches the head surface of the screw 1. The fitting portion 14 is slightly left at the deepest portion of the drive hole 10, and the relief portion 16 in which the meat of the fitting portion 14 is removed is formed on the upper portion thereof, and as shown in FIG.
The relief portion 16 is a parallel surface 17 parallel to the axis of the screw 1. On the other hand, the lower end of the escape portion 16 is formed flat, and the fitting portion 14 is provided at the upper portion of the escape portion 16 with the screw 1
Is formed over the surface of the head 2. in this way,
Fitting portions 14 are arranged above and below the escape portion 16 so as to sandwich it, and when the driver bit 20 is fitted into the driving hole 10, the connecting portion 22 of the driver bit 20 causes the fitting portion 14 of the driving hole 10 to fit. When the driver bit 20 is rotationally driven to start the screw tightening work, the connecting portion 22 at the base of the driver bit 20 is finally disengaged from the fitting portion 14 as shown in FIG. The engaging blade 21 of the driver bit 20 abuts the side surface 13 of the engaging groove 11 of the drive hole 10 so that the driving force is transmitted.

When tightening the screw 1 constructed as described above to a work (not shown), the head 2 of the screw 1 is driven at the tip of the driver bit 20 in advance to the screw hole (not shown) of the work. After the holes 10 are fitted together, the leg portions 4 of the screw 1 are pressed to apply a rotational driving force to the driver bit 20 as shown in FIG. At this time, the driving force rises slightly out of the fitting portion 14 of the screw 1 into which the tip of the driver bit 20 is fitted, but rises.
As shown in FIGS. 5 and 6, the connecting portion 22 of the base portion, which is the base of the engaging blade 21 of FIG. 5, is fitted into the escape portion 16 of the driving hole 10, and the driving surface of the engaging blade 21 has the engaging groove 11
It comes into surface contact with the side surface 13 of the.

As a result, the screw 1 has a driver bit 2
The rotational driving force from 0 is transmitted to the engagement groove 11 via the engagement blade 21 and screwed into the work. In this way, the screw 1 is screwed into the work by a predetermined amount, and the screw 1 is attached to the surface of the work.
When the seat surface 5 is seated on the screw 1, the resistance increases in opposition to the screw tightening torque, and the screw 1 has a preset screw tightening torque. On the other hand, since the drive hole 10 of the screw 1 and the engaging blade 21 of the driver bit 20 are still in surface contact with each other, the so-called cam-out phenomenon in which the driver bit 20 slides out of the drive hole 10 is hard to occur and is stable. A screwing torque will be obtained.

[0011]

As is apparent from the above-described embodiments of the present invention, the drive hole 10 with which the driver bit 20 having the engaging blade 21 and the base portion of the base of the engaging blade 21 is engaged is formed. In a screw with a cross hole composed of a head portion 2 and a leg portion 4 in which a screw thread 3 is formed, a sloped surface that constitutes a drive hole 10 and the facing distance b becomes closer as the depth becomes deeper between the engaging grooves 11 adjacent to each other. And a parallel surface 1 parallel to the axis is formed on the inclined surface of the fitting portion 14.
7 is provided with a relief portion 16 from which the meat is removed, and the fitting portion 14 formed of the sloped surface is sandwiched between the relief portions 16 so as to bite into the connection portion 22 of the driver bit 20.
Since it is a screw with a cross hole that remains, even if this screw is screwed in using a normally used driver bit, the camout phenomenon does not easily occur at the end of screwing. Therefore, the preset screw tightening torque can be accurately obtained. Further, in the automatic assembly work line, the screw tightening torque is managed, but by using this screw, variations in the screw tightening torque are eliminated, and the occurrence of product defects is reduced. Further, conventionally, it was necessary to apply a large thrust to the driver bit in order to eliminate this come-out phenomenon, but this can be reduced, and the work is not distorted.

Moreover, since the bottom surface of the escape portion 16 is a flat surface perpendicular to the axis, the rotational driving force of the driver bit is surely transmitted to the engagement groove of the drive hole via the engagement blade, and is required. Stable screw tightening torque is transmitted. Further, since the fitting portion 14 located below the relief portion 16 is lower in height than the fitting portion 14 located above, the bite of the driving hole for the screw can be stably obtained at the tip of the driver bit. At the same time, a unique effect such as no adverse effect on the transmission of the screw tightening torque is obtained.

[Brief description of drawings]

FIG. 1 is a sectional front view of a main part of a screw showing an embodiment of the present invention.

FIG. 2 is an enlarged plan view of FIG.

FIG. 3 is a cross-sectional view of relevant parts taken along the line AA in FIG.

FIG. 4 is a sectional front view of a main part of a screw showing a usage pattern of the present invention.

FIG. 5 is an enlarged cross-sectional view of an essential part showing an engagement state between a drive hole and an engagement blade.

6 is an enlarged cross-sectional view of a main part taken along the line BB in FIG.

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

FIG. 8 is an enlarged cross-sectional view of an essential part showing a fitting state of a conventional screw and a driver bit.

[Explanation of symbols]

1 screw 2 heads 3 screw threads 4 legs 5 seat 10 drive hole 11 engaging groove 12 Bottom 13 sides 14 Fitting part 15 ridge 16 escape area 17 Parallel plane 20 driver bits 21 Engaging blade 22 Connection

Claims (3)

[Claims] 1. A head having a drive hole (10) in the shape of a cross hole, into which a driver bit (20) having a cross-shaped engagement blade (21) and a base portion serving as the base of the engagement blade is engaged. In a screw having a cross hole, which is composed of (2) and a leg portion (4) which is integrated with the leg portion (4) and which is formed with a screw thread (3), the engagement holes (11) which form the drive hole and are adjacent to each other A fitting portion (1) made of a slope whose facing distance b becomes closer as the connecting portion (22) between the engaging blades of the driver bit is fitted deeper between them.
4) is formed, and a relief portion (16) whose meat is removed is provided on the inclined surface of the fitting portion so as to have a parallel surface (17) parallel to the axis, and the driver bit is provided above and below the relief portion. A screw having a cross hole, characterized in that a fitting portion composed of the inclined surface is left so as to bite into the connection portion of. 2. The screw with a cross hole according to claim 1, wherein a bottom surface of the relief portion is a plane perpendicular to the axis. 3. The screw with a cross hole according to claim 1, wherein the fitting portion located below the relief portion has a lower height than the fitting portion located above.