JPH0953619A - Head part buried type screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cost by forming a forging metal mold for forming the top part of a screw at low cost and in a long life. SOLUTION: In a wood screw, a spiral screw head is formed on the outer peripheral part from a tip end of an axial body 22 to an intermediate part, and a head part 23 is formed on the other end of the axial body 22. The axial body 22 of the head part 23 is formed as a slant surface 24, and a plurality of cut edges 25 are formed on the axial body 22 side of the outer peripheral rim of the head part 23. When the wood screw is screwed on a wood and the head part attains the wood, the slant surface 24 is buried in the wood to a substantial depth by only screwing the wood screw. When the wood approaches the top surface or the head part, spot facing is started by the cut edges 25, and the wood screw is buried until the top head 23 is flush with the wood.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw including a wood screw, a tapping screw and the like, and more particularly to a screw in which when screwed in, the head is counterbored by itself to bury the head.

[0002]

2. Description of the Related Art Screws such as bolts, screws, tapping screws, and wood screws are used to connect two members. Generally, one end of a shaft body having a spiral thread is formed on the shaft. A head with a diameter larger than the body is provided.

Of the two joining members joined by such screws, when the member on the head side is a relatively soft material such as wood or gypsum board, an inclined surface is provided on the shaft side of the head. The screws that they have, in other words, the screws that have a head that opens like a trumpet from the shaft are often used. This is because when the screw is tightened, this inclined surface is made to bite into soft wood or gypsum board, the head of the screw is embedded in the connecting member, and the top surface of the head and the surface of the connecting member are covered. This is to make one.

However, as long as the connecting member is made of soft wood or the like, in the case of hard wood or the like, the head cannot be easily buried in the connecting member, no matter how much the inclined surface is. Moreover, since the diameter of the peripheral portion of the head increases rapidly, it is difficult to bury the flat top surface of the head until it is flush with the fastening member, that is, flush.

As a means for solving such a problem, a head buried type wood screw shown in FIG. 6 is known. The wood screw shown in the figure has a driver groove (not shown) at one end of the shaft body 1.
Although the head 2 having the above is formed, the head 2 has two inclined surfaces 3a and 3b having different slopes on the side of the shaft 1 so that the shaft and the head are smoothly connected. . A plurality of inclined blades 4 are formed on the inclined surfaces 3a and 3b, and further, a plurality of cutting blades 5 are provided on the outer peripheral edge of the head 2 on the shaft body 1 side.
Are formed. The cutting blade 5 is formed intermittently in the circumferential direction, and has a substantially triangular cross section as shown in FIGS. 6 and 8.

When this wood screw is screwed into wood or the like, it is screwed in from the tip of the shaft body 1 in which the thread is formed, and eventually the lower end of the inclined surface 3b of the head 2 reaches the surface of the wood. When the wood screw is further screwed in, the beveled blade 4 countersinks itself to promote the embedding of the head 2, and finally the cutting blade 5 counterbores along the outer peripheral edge of the head 4 to make the head 2 wood. It becomes buried in the same place and becomes flat.

FIGS. 7 and 8 are views showing a die 10 for forging forming such a head. In FIG. 8, there is an inclined surface 11 having a V-shaped cross section for forming the inclined surfaces 3a and 3b of the head 2 at the upper part of the mold 10, and the inclined surface 11 is formed at the center thereof. A hole 12 for connection is formed. Then, six inclined grooves 13 for forming the inclined blade 4 are dug on the inclined surface 11, and six V grooves 14 for forming the cut blade 4 are formed on the top surface of the mold 10. It is formed radially.

A round bar (not shown), which is the material of the wood screw, is inserted into the central hole 12 of the mold 10, and in FIG.
When the die on the mating side (not shown) is strongly pushed down, the beveled blade 4 and the cutting blade 5 as shown in FIG. A round bar having a head portion 2 having an arrowhead is formed. After that, the round bar portion is processed with a rolling die to form the shaft 1 and the screw thread on the tip side thereof, and at the same time, the tip of the shaft 1 is sharpened to complete the wood screw.

[0009]

However, in the wood screw described above, the V groove 14 and the inclined groove 13 must be formed in the die 10. Since the inclined groove 13 is formed on the slope, the forming work is difficult. Also, since it is a fine groove, it is easily worn during forging. Further, the V groove 14 has a sharp ridge line P on the inner side thereof, and this portion is also easily worn.
As a result, the life of the mold is reduced to about 1/2 of the normal life, and as a result, the manufacturing cost of the wood screw is greatly increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a mold with a low cost and a long life, and as a result, to provide an inexpensive head recess type screw.

[0011]

In order to achieve the above-mentioned object, the present invention comprises a shaft body having a spiral thread formed on the outer peripheral surface thereof, and a head formed at one end of the shaft body. In this screw, a plurality of cutting blades are formed on the shaft body side of the outer circumference of the head.

Alternatively, it is composed of a head portion having a driver groove formed on a substantially flat top surface and a shaft body having a spiral thread formed on the outer peripheral surface having a sharp tip, and the head portion is inclined toward the shaft body side. A screw having a surface is characterized in that a plurality of cutting blades extending in the radial direction of the shaft body and substantially horizontally are formed on the outer peripheral edge of the head portion on the shaft body side.

It is preferable that the inclined surface has an arcuate cross-sectional shape or the cutting blade has a triangular cross-sectional shape. The cross-sectional shape may be an isosceles triangle.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a wood screw of the present invention. Similar to the wood screw shown in the conventional example of FIG. 6, this wood screw has a head portion 23 formed at one end of the shaft body 22.
Although the other end not shown is omitted, the tip is sharp,
A spiral thread is formed on the outer peripheral portion.

This wood screw has an inclined surface 24 on the shaft 22 side of the head 23, but unlike the conventional example, the inclined surface has an arc-shaped cross section. Then, on the inclined surface 24,
There is nothing corresponding to the beveled blade 4 in the conventional example, and the head 2
Only a plurality of (8) cutting blades 25 are formed on the outer peripheral edge of the shaft body 3 on the shaft body 22 side.

Moreover, the cutting blade 25 of the present invention is common to the cutting blade 5 shown in the conventional example in that the cross-sectional shape is triangular, but is different in the following points. First,
The conventional cutting blade 5 is formed in the circumferential direction, but the cutting blade 25 of the present invention is formed in the radial direction. Further, the cutting blade 5 of the conventional example is inclined in the radial direction,
As shown in FIG. 8, the die had a sharp ridge line like the P portion, but the cutting blade 25 of the present invention is horizontal in the radial direction.

As described above, the wood screw of the present invention does not have the beveled blade 4 shown in FIG. 6, which means that the present invention can be compared by simply screwing the portion of the inclined surface 24 to a considerable depth. It is because it was discovered that it can be buried easily. In particular, if the inclined surface 24 has an arc shape, below the inclined surface 24, the angle α between the inclined surface 24 and the shaft body 22 is formed.
1 becomes smaller and the outer diameter of the screw thread is larger than the outer diameter of the shaft body 22, so that it is easy to enter. Even so, when it comes above the inclined surface 24, the angle α2 formed by the inclined surface and the shaft body becomes large and it becomes difficult to enter, but at that time, since the cutting blade 25 starts counter boring, the head 23 is buried. As a result, the head 23 is finally buried in the wood and becomes flush.

The inclined surface 24 is not limited to a circular arc, and may be a straight line (cone) or a V shape as in the conventional example. In that case, the screwing resistance is slightly increased, but the head 23 can be buried.

2 and 3 show a mold forming the head of a wood screw according to the present invention. In FIG. 3, at the upper end of the mold 30, there is an arcuate surface 31 for forming the inclined surface 24 of the head 23, and at the center thereof, a hole 32 that is gently connected to this surface 31 is formed. ing. And the mold 30
A horizontal V for forming the cutting blade 25 on the top surface of the
Eight grooves 34 are formed radially, but the arc-shaped surface 3
1 does not have the inclined groove 13 for forming the inclined blade 4 in the conventional example. Further, the sharp V-shaped groove P, which was present in the conventional example, cannot be formed in the horizontal V groove 34.

According to the present invention, since the inclined groove 13 and the sharp ridge P which are most easily worn as described above can be eliminated,
The life of the mold can be extended to the same level as usual, and it is possible to provide inexpensive screws and wood screws. Of course, the fact that the head of the screw is buried in the fastening member so as to be flush with the fastening member can be secured to the same extent as in the conventional case.

4 and 5 are views showing another embodiment of the present invention. The same components as those in the above-described embodiment are designated by the same reference numerals. In this embodiment, the number of cutting blades 28 is 6
The cross-sectional shape is an isosceles triangle. Thus, the number and shape of the cutting blades can be set arbitrarily. Then, as in this embodiment, by making the cross-sectional shape an isosceles triangle, forging was facilitated and the horizontal V groove 35 itself of the mold was also less likely to wear.

[Brief description of drawings]

FIG. 1 is a front view showing a screw head of an embodiment of an embedded head type screw according to the present invention.

2 is a top view of a mold forming the head of the screw of FIG. 1. FIG.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a front view showing another embodiment of the present invention.

5 is a top view of a mold forming the screw head of FIG. 4. FIG.

6A and 6B are views of a conventional buried head type screw, in which FIG. 6A is a front view and FIG. 6B is a sectional view taken along line BB of FIG.

FIG. 7 is a top view of a mold for forming a conventional screw head.

FIG. 8 is a sectional view taken along line CC of FIG.

[Explanation of symbols]

 22 Shaft 23 Head 24 Slope 25, 28 Cutting blade

Claims (5)

[Claims] 1. A screw comprising a shaft body having a spiral thread formed on the outer peripheral surface thereof, and a head formed at one end of the shaft body, wherein a plurality of screws are provided on the shaft body side of the head periphery. A recessed head screw that is formed with a cutting blade. 2. A head portion having a driver groove formed on a substantially flat top surface and a shaft body having a spiral thread formed on the outer peripheral surface having a sharp tip, and the head portion is inclined toward the shaft body side. In a screw having a surface, a head embedded type screw, wherein a plurality of cutting blades extending in a radial direction of the shaft body and substantially horizontally are formed on an outer peripheral edge of the head body on the shaft body side. 3. The embedded head type screw according to claim 1, wherein the inclined surface has an arcuate cross-sectional shape. 4. The embedded head type screw according to claim 1, wherein the cross section of the cutting blade is triangular. 5. The embedded head type screw according to claim 4, wherein the cross-sectional shape is an isosceles triangle.