JPH0719218A - Screw for soft cutting material - Google Patents

Abstract

PURPOSE:To provide a screw that is screwed in soft cutting materials such as colored bestos and ALC, at a time when clamping torque is received after securing is finished, it is so structured that a screw head is locked to a surface of the soft cutting material so as not to incur a stripped screw state as it is forcibly turned round and thereby the soft cutting material is broken down. CONSTITUTION:In a screw installed with a shank 5 extendedly from a head part 3 via a neck part 4, this head part 3 is provided with a pressure contact surface 9 spreading over an outer boundary of the neck part 4, and a lot of damping ribs 10 extending almost in the radial direction are installed on the pressure contact surface 9 in formation in the circumferential direction as the constitution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded tile material such as a color vest or a full vest, and a soft-cutting material produced by molding a powder material as seen in an aerated concrete base material such as ALC. Regarding screws for use.

[0002]

2. Description of the Related Art Conventionally, a molded roof tile material such as a color vest or a full vest, and a cellular concrete base material such as ALC have been produced by molding a powder or granular material and widely used as a building material.

In such a building material, when the screw is screwed in, the material is easily cut, while when the screw is strongly tightened, the material is easily collapsed, and the screw connection part engaged with the screw is broken. And the screw slips. In the present invention,
Such a material is called a "soft-cutting material", and a screw screwed into such a soft-cutting material for use is called a "soft-cutting material screw".

[0004]

As described above, since the soft-cutting material has a fragile structure, it is possible to easily screw in the screw. That is, by screwing the screw, a female screw is easily formed in the soft-cut material.

Incidentally, it is desirable that the head of a screw used for a collar vest or the like does not protrude from the collar vest. For this reason, it has a flat head and a tapered neck having a larger outer diameter from the shank to the head, and is called a so-called countersunk head as a whole.

When such a countersunk head screw is screwed into a soft-cutting material such as a collar vest, the shank advances in correspondence with the pitch of the thread, while the tapered neck portion forming the countersunk head is made of a soft-cutting material. Difficult to enter the surface of. Therefore, if the tapered neck portion does not enter on the surface of the soft-cutting material and runs idle, the thread of the shank that has been screwed in earlier breaks the screw engaging portion cut in the soft-cutting material, resulting in a so-called stupid screw state. I will be invited.

Even if the tapered neck portion satisfactorily penetrates into the soft-cutting material and tightens the screw by tightening the screw, if the tightening torque is further applied to the screw after tightening, the softening material is softened. Easily breaks the female screw machined in the work material and causes the screw to idle, which also causes a stupid screw state. Then, once the stupid screw state is brought, it becomes impossible to refasten the screw at the relevant portion.

Such a stupid screw state after tightening the screws poses a serious problem with the spread of electric screwdrivers in recent years. When working with an electric screwdriver, it is difficult to stop the driver at the same time as tightening after screwing the screw into the soft-cutting material.Normally, the driver's stop is delayed, so the screw will not work after tightening. This is because the excessive tightening torque easily causes the above-mentioned stupid screw state.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above problems and is configured so that the neck portion of a screw can easily enter a soft-cutting material, and the neck portion enters the soft-cutting material to complete fastening. Immediately, the screw itself is locked against rotation with respect to the soft-cutting material, and thereafter, even if a tightening torque is applied to the screw with an electric screwdriver, etc., the rotation of the screw is blocked, resulting in a stupid screw state. Provided is a screw for soft-working material, which is designed to prevent

Therefore, the present invention is configured as a first means in a screw in which a shank is extended from a head having an engaging portion of a rotary tool through a neck, and a thread is formed on the shank, The neck portion constitutes a tapered neck portion that gradually increases the outer diameter to reach the head portion, and the outer peripheral surface of the tapered neck portion is provided with cutting ribs extending in the axial direction in a row in the circumferential direction. The point is that the head has a pressure contact surface that spreads to the outer periphery of the neck portion, and braking ribs extending substantially in the radial direction are arranged in a row in the circumferential direction on the pressure contact surface.

In the first means, each of the braking ribs forms a braking surface facing the forward rotation direction of the head and a groove surface facing the reverse rotation direction of the head, and the braking surface is formed by a screw. It is preferably formed along a plane substantially parallel to the axis.

Further, it is preferable that each of the cutting ribs is provided with a cutting blade, and the blade edge of the cutting blade in the cutting rib is arranged so as to face the groove surface of the braking rib.

According to the second aspect of the present invention, in a screw in which a shank is extended from a head having an engaging portion of a rotary tool and a thread is formed on the shank,
The head is provided with a pressure contact surface that is in pressure contact with an object to be fastened, and braking ribs that extend in a substantially radial direction are arranged in a row in the circumferential direction on the pressure contact surface. A braking surface facing the forward rotation direction and a groove surface facing the reverse rotation direction of the head are formed, and the braking surface is formed along a surface substantially parallel to the axis of the screw.

[0014]

Embodiments of the present invention will be described in detail below with reference to the drawings.

(First Embodiment) In FIG. 1, a screw 1 for a soft-working material has a shank 5 through a neck 4 through a head 3 having an engaging portion 2 for engaging a rotary tool such as an electric screwdriver. And a screw thread 6 is formed on the shank 5.
In addition, although the engaging portion 2 shows a plus groove in the illustrated example,
It may be a minus groove or a hexagonal hole, or may be a hexagonal protrusion protruding from the top of the head 3.

The neck portion 4 constitutes a tapered neck portion whose outer diameter gradually increases from the shank 5 to the head portion 3, and the head portion 3 constitutes a circular flange which spreads on the outer circumference of the neck portion 4,
A so-called dish-shaped head is formed as a whole.

On the outer peripheral surface of the tapered neck portion 4, cutting ribs 7 extending substantially in the axial direction are arranged in a row in the circumferential direction.
In the illustrated example, 16 cutting ribs 7 are provided at equal intervals in the circumferential direction, but the number is not limited.

In the first embodiment, as shown in FIG. 1D, the cutting rib 7 is formed in a mountain-shaped cross section, and the cutting edge 8 is constituted by the top edge.

The head 3 is a surface that extends to the outer periphery of the neck 4,
That is, a pressure contact surface 9 is provided on the surface facing the shank 5, and braking ribs 10 extending substantially in the radial direction are arranged in a row in the circumferential direction on the pressure contact surface 9. In the illustrated example, 16 braking ribs 10 are provided at equal intervals in the circumferential direction, but the number thereof is not limited.

In the first embodiment, the braking rib 10 is
As shown in FIG. 1 (D), a braking surface 11 that faces the forward rotation direction F of the head 3 and a groove surface 12 that faces the reverse rotation direction of the head 3 (opposite to the above F) are formed, and the braking is performed. The surface 11 is formed on a surface substantially parallel to the axis of the screw. That is, the braking surface 11 is
It stands up from the press contact surface 9 at an angle of approximately 90 degrees.

The cutting blade 8 of the cutting rib 7 extends toward the braking rib 10.
1C without connecting to the braking surface 11 of FIG.
As shown in (D), the cutting blade 8 is displaced from the braking surface 11 and is continuously provided toward the groove surface 12 of the braking rib 10.

According to the configuration of the first embodiment, the soft-cutting material 1
When a screw 1 is screwed into the soft-cutting material 13 from the sharpened portion 1a at the tip without making a prepared hole in the 3 or without making a prepared hole, the thread 6 taps the internal thread in the soft-cutting material 13 and shank. Screw in 5.

When the neck portion 4 of the screw 1 reaches the soft-cutting material 13 by screwing, the cutting rib 7 of the neck portion 4 cuts the soft-cutting material 13 and forms the tapered hole to form the soft-cutting material of the neck portion 4. Enter during 13. For this reason, the shank 5 screwed into the soft-cutting material 13 first enters the soft-cutting material 13 in accordance with the pitch of the thread 6 and is engaged with the thread 6 (the soft-cutting material 13). Do not destroy the female screw tapped on.

When the neck portion 4 enters the soft-cutting material 13, the head portion 3
The pressure contact surface 9 of is pressed against the soft-cutting material 13. On this occasion,
As shown in FIG. 2 (A), as the screw 1 rotates, the braking rib 10 is rubbed against the surface of the soft-cutting material 13 while the braking surface 11 is being rubbed.
Are bitten into the soft-cutting material 13. When the braking surface 11 of all the braking ribs 10 bites into the soft-cutting material 13 due to the screwing of the screw 1, the head 3 is prevented from rotating in the forward rotation direction F and is locked. The screw 1 does not rotate even if the portion 3 receives a tightening torque from an electric screwdriver or the like. Therefore, the screw 1 maintains the state in which the thread 6 of the shank 5 is fastened to the internal thread machined in the soft-cutting material 13.

By the way, when the neck portion 4 enters the soft-cutting material 13, chips of the soft-cutting material 13 cut by the cutting ribs 7 are generated. According to the configuration of the first embodiment, the cutting chips are produced. Are dispersed and / or easily discharged to the outside, and the biting of the braking rib 10 to the soft-cutting material 13 that is subsequently performed is made good.

That is, as shown in FIG. 2B, when cutting the soft-cutting material 13 by the rotating neck portion 4, the cutting rib 7 has the cutting blade 8 as a boundary and the flank 7 on the front side in the rotation direction.
Although chips will be generated at the portion a, according to the above-described embodiment, since the cutting edge of the cutting blade 8 is arranged toward the groove surface 12 of the braking rib 10, the chips are used for braking. It can be guided to the groove surface 12 of the rib 10. Then, the cutting chips guided to the groove surface 12 are easily discharged in the outer peripheral direction of the head 3 as shown by the arrow while being dispersed along the inclined surface when pressed by the groove surface 12. As a result, the subsequently advancing braking rib 10 is appropriately bited into the surface of the soft-cutting material 13.

Regarding this point, as shown in FIG.
The cutting edge of the cutting blade 8 in the cutting rib 7 is provided with the braking rib 10.
In the case of the configuration (comparative example) in which the braking ribs 11 are arranged so as to coincide with each other, it is relatively difficult to bite the braking rib 10 into the surface of the soft-cutting material 13. That is, in the case of this comparative example, the soft-cutting material 13 cut by the cutting ribs 7 of the neck portion 4
Since the chips of (3) are immediately caught in the braking surface 11 of the braking rib 10, they are solidified on the braking surface 11. In other words,
The chips are mainly solidified around the neck portion 4 and are not dispersed, so that they are allowed to remain between the surface of the soft-cutting material 13 and the press-contact surface 9 of the head 3, and the press-contact surface 9 is softened. It makes it difficult to press-contact the surface of 13.

It should be noted that the present invention does not exclude such a comparative example, but explains that the structure of the first embodiment is superior to this comparative example.

(Second Embodiment) In the second embodiment shown in FIG. 4, the cutting rib 7 has a structure similar to that of the braking rib 10. That is, the cutting rib 7 is formed with a flank 7a on the front side of the cutting blade 8 in the forward rotation direction on a flat surface that stands up at an angle of approximately 90 degrees from the tapered outer peripheral surface of the neck portion 4.
The other structure is similar to that of the first embodiment.

According to the structure of the second embodiment, when the neck portion 4 enters the soft-cutting material 13, the flank 7a on the front side in the forward direction of the cutting rib 7 cuts the soft-cutting material 13 and applies the braking force. Then, the braking rib 10 of the head 3 is received by the soft-cutting material 1 after that.
When cutting into the surface of No. 3, cutting rib 7 and braking rib 1
The forward rotation of the screw 1 is braked by both 0, and the rotation of the screw 1 is surely blocked and locked.

Further, the sharpness of the cutting blade 8 in the cutting rib 7 becomes sharp, so that the cutting force when the neck portion 4 enters the soft-cutting material 13 is excellent.

(Other Embodiments) Needless to say, the present invention is not limited to the above-mentioned embodiments. For example, instead of the tapered neck portion 4, a screw without a neck is constructed, and the like. Various other configurations can be adopted.

[0033]

According to the present invention as set forth in claim 1, when the screw 1 is screwed into the soft-cutting material 13, the tapered neck portion 4 easily enters the surface of the soft-cutting material 13 via the cutting rib 7. Since the screw 1 is tightened, the screw 1 corresponding to the pitch of the screw thread 6 can be screwed in between, and when the screw 1 is tightened,
The braking rib 10 of the head 3 is made to bite into the surface of the soft-cutting material 13 to prevent the screw 1 from rotating and to lock it. As a result, when the screw 1 is fastened to the soft-cutting material 13 having a fragile structure, a so-called stupid screw state unlike the conventional case does not occur, work can be facilitated, and the best screw can be used. There is an effect that the tightened state can be obtained.

According to the present invention as defined in claim 2, the braking rib 10 extends along a plane substantially parallel to the axis of the screw.
Therefore, there is an effect that the lock function of the screw 1 at the time of tightening is excellent.

According to the present invention as defined in claim 3, the neck 4 is
Cutting chips generated when the material enters the soft-cutting material 13
Since it can be dispersed by the groove surface 12 of 0 and easily discharged to the outside, the cutting chips interfere between the pressure contact surface 9 of the head 3 and the surface of the soft-cutting material 13, and the braking rib 10 is formed. It does not prevent the soft-cutting material 13 from digging into the surface of the soft-cutting material 13, and has the effect of ensuring the desired braking function.

According to the invention of claim 4, the screw 1
At the time of tightening, the braking rib 10 of the head 3 is caused to bite into the surface of the soft-cutting material 13 to prevent the screw 1 from rotating and to lock, so that the screw 1 is not attached to the soft-cutting material 13 having a fragile structure. When tightening the screws, there is an effect that a so-called stupid screw state unlike the conventional case does not occur, work can be facilitated, and the best screw tightened state can be obtained.

[Brief description of drawings]

FIG. 1 shows a first embodiment of the present invention, (A) is a front view, (B) is a plan view, (C) is a sectional view taken along line C-C,
(D) is a perspective view showing a main part.

2A and 2B show an operation of one embodiment of the present invention, FIG. 2A is an enlarged cross-sectional view when fastening is completed, and FIG. 2B is an enlarged front view showing a chip discharging operation.

FIG. 3 is an enlarged front view showing the operation of the comparative example with respect to the first embodiment of the present invention.

FIG. 4 is an enlarged perspective view showing a main part of a second embodiment of the present invention.

[Explanation of symbols]

 1 Screw for Soft Cutting Material 2 Tool Engaging Part 3 Head 4 Neck 5 Shank 6 Screw Thread 7 Cutting Rib 8 Cutting Blade 9 Pressure Contact Surface 10 Braking Rib 11 Braking Surface 12 Groove Surface 13 Soft Cutting Material

Claims (4)

[Claims] 1. A screw in which a shank is extended from a head provided with an engaging portion of a rotary tool via a neck, and a thread is formed on the shank, and the outer diameter is gradually increased when the neck reaches the head. A tapered neck portion is formed, and cutting ribs extending substantially in the axial direction are circumferentially arranged on the outer peripheral surface of the tapered neck portion in a circumferential direction, and the head has a pressure contact surface that extends to the outer periphery of the neck portion. A screw for a soft-working material, characterized in that braking ribs extending substantially in the radial direction are arranged in a row in the circumferential direction on the press contact surface. 2. Each of the braking ribs forms a braking surface that faces the forward rotation direction of the head and a groove surface that faces the reverse rotation direction of the head, and the braking surface is substantially parallel to the axis of the screw. The soft-working material screw according to claim 1, wherein the screw is formed along a surface. 3. Each of the cutting ribs includes a cutting blade,
The screw for soft-cutting material according to claim 2, wherein the cutting edge of the cutting blade of the cutting rib is arranged toward the groove surface of the braking rib. 4. A screw in which a shank is extended from a head provided with an engaging portion of a rotary tool, and a thread is formed on the shank, the head having a press contact surface for press contacting an object to be fastened, Brake ribs extending in a substantially radial direction are arranged in a row in the circumferential direction on the press contact surface, and each of the brake ribs faces a forward rotation direction of the head and a reverse rotation direction of the head. And a groove surface and the braking surface is formed along a surface substantially parallel to the axis of the screw.