JPH0721924Y2 - Tightening screws for hard parts - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION This invention relates to a tightening screw for fixing various members to a hard member such as concrete or brick, and more specifically, to the hard member, there is no breakage of the hard member at the time of tightening and rattling. The present invention relates to a tapping screw that can obtain a tight tightening state without any damage.

[0002]

2. Description of the Related Art For hard members such as concrete and bricks,
A conventional tapping tightening screw used for fixing various members such as an angle, a channel, and a plate is provided with a head to which an electric screwdriver or the like is coupled at one end of a shaft portion, and a guide screw and a guide screw are provided on the outer periphery of the shaft portion. It has a structure in which a tapping screw having a diameter slightly larger than that of the guide screw is formed.

In order to use this tightening screw, it is sufficient to previously provide a hard member with a pilot hole having a diameter equal to or slightly smaller than the diameter of the guide screw and screw the tightening bolt inserted into the fixed member into the pilot hole with a screwdriver. The guide screw guides the shaft portion to enter along the pilot hole, and the thread crests of the tapping screw enter while cutting the peripheral wall of the pilot hole.

By the way, in order to increase the pull-out resistance of the conventional tightening screw as described above, the tapping screw should have a large diameter and the amount of the tapping screw with respect to the hard member should be increased. Although the diameter of the tapping screw is gradually increased toward the head side, etc., if the biting amount increases, the resistance at the time of screwing in during screwing becomes large and it becomes impossible to screw in with an electric screwdriver. Actually, the diameters of the tapping screw and the guide screw can be set to a slight difference.

[0005]

Therefore, during tightening work, there is no fluctuation in the torque required for screwing from the start of screwing into the pilot hole to the completion of tightening. Therefore, at the same time when tightening is completed, an excessive screwing torque of the electric screwdriver is applied. When the force acts, the tapping screw rotates too much, the tapping screw breaks the inner peripheral wall of the pilot hole, and idle rotation occurs, so that the tightened state cannot be obtained.

In order to solve the above-mentioned problems, the present invention provides a tightening screw in which the tapping screw does not destroy the inner peripheral wall of the pilot hole when the tightening is completed and a strong tightened state is obtained. Is an issue.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention proposes a guide screw and a guide screw on the outer periphery of a shaft portion having a head at one end and a tip end at the other end. In a tightening screw for a hard member having a tapping screw with a larger diameter, the guide screw and the tapping screw each have a constant diameter from the tip side to the middle of the head, and the guide screw between the middle and the head. Is the diameter of the tapping screw, and the tapping screw is the diameter of the guide screw.

[0008]

[Operation] When the hard member is screwed into the pilot hole, the guide screw guides the shaft portion along the pilot hole to enter, and the screw crest of the tapping screw enters the pilot hole while cutting the inner peripheral wall of the pilot hole.
When it reaches just before the completion of tightening, the tapping screw and the guide screw are swapped, so the screw crest of the part where the tapping screw and the guide screw are swapped, the guide screw on the tip side with respect to the inner peripheral wall of the pilot hole The part that has not been cut is bitten, thereby increasing the screwing resistance, preventing damage to the hard member due to over-turning, and preventing rattling in the screwed state.

[0009]

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

As shown, the tightening screw has a shank 1
A head 2 provided at one end of the shaft 1, a guide screw 3 provided on the outer periphery of the shaft 1, and a tapping screw 4 similarly provided on the outer periphery of the shaft 1. And the tapping screw 4 is provided so as to be replaced at a position near the head 2.

The guide screw 3 and the tapping screw 4 are alternately formed on the outer periphery of the shaft portion 1 at an equal pitch.
Has the same diameter over the entire length except for the portion where the tapping screw 4 is replaced.

The tapping screw 4 is the guide screw 3
The diameter is slightly larger than that of the guide screw 3, and the entire length is formed to have the same diameter except for the portion where the guide screw 3 is inserted.

The part where the guide screw 3 and the tapping screw 4 are replaced is located at a position close to each head 2.
The guide screw 3 has a large diameter portion 3a having a diameter substantially equal to that of the tapping screw 4, and the tapping screw 4 has a small diameter portion 4a having a diameter substantially equal to that of the guide screw 3.

The position of the portion where the guide screw 3 and the tapping screw 4 are exchanged from the head portion 2 may be appropriately selected according to the thickness of the member 11 to be tightened, and the large diameter portion 3a and the small diameter portion 4a. The length in the circumferential direction may be selected according to the material of the hard member 12. For example, in the case of an extremely hard member, the length may be shortened so as to prevent generation of strong screwing resistance.

Further, in the case of the head 2, the engaging groove 5 of the electric driver is provided on the upper surface in the case of the illustration, but a hexagonal head may be adopted, and the tip portion 1a of the shaft portion 1 is as shown. It is not limited to a sharp shape.

The tightening screw of the present invention has the above-mentioned structure, and the hard member 12 has the prepared hole 13 having a diameter equal to or slightly smaller than the diameter of the guide screw 3, and the tightening member 11 has the tapping screw 4 attached thereto. Through hole 1 through which the outer diameter of
4 are drilled respectively.

The tightening screw inserted into the through hole 14 is attached to the lower hole 1
For 3, screw in while rotating it with an electric screwdriver.

At this time, as shown in FIG. 2, the guide screw 3 guides the shaft portion 1 from entering the lower hole 13, and
The tapping screw 4 bites into the inner peripheral wall of the pilot hole 13 in a cut shape, and allows the shaft portion 1 to enter along the spiral shape, and the cut piece is housed in the space between the screws 3 and 4.

When the screwing of the tightening screw reaches just before the completion of tightening, as shown in FIG. 2 (B), the part where the guide screw 3 and the tapping screw 4 are exchanged enters into the prepared hole 13 and the guide screw 3 The large-diameter portion 3a bites into the inner peripheral wall of the pilot hole 13 in a notch shape to the threaded portion that was hardly formed by the guide screw 3 on the tip side, and the small-diameter portion 4a of the tapping screw 4 is formed by the tapping screw 4 on the tip side. It separates from the formed screw path 15.

As described above, the large diameter portion 3a of the guide screw 3
If the bite bites into the hard member 12, the screwing resistance increases and the screwing torque of the electric screwdriver is suppressed.

For this reason, when the tightening screw is screwed in, the approach speed decreases from immediately before the completion of tightening until the completion of tightening where the head 2 presses the member 11 to be tightened against the hard member 12, and when the tightening is completed, the electric screwdriver becomes excessive. This prevents the tightening bolt from turning too far due to excessive rotation.

[0022]

[Effects] As described above, according to the present invention, since it has the above-mentioned configuration, the following effects are obtained.

(I) In a tightening screw for a hard member, which is provided with a guide screw on the outer periphery of the shaft portion and a tapping screw having a diameter larger than this guide screw, the guide screw and the tapping screw are in the middle of the head portion from the tip side. The diameters of the guide screw and the tapping screw were reversed from the middle to the position between the heads, so the part where the guide screw was replaced with the tapping screw dig into the inner wall of the pilot hole just before the screwing is completed. As a result, the screwing resistance increases immediately before the screwing is completed until the screwing is completed, resulting in a braking effect, suppressing the screwing torque of the electric screwdriver, etc., and the tapping screw destroys the inner peripheral wall of the pilot hole due to excessive rotation due to excessive rotation. It is possible to prevent the occurrence of idle rotation. Further, since the guide screw is substantially provided over the entire length of the shaft portion, it is possible to guide the entry of the shaft portion into the pilot hole over the entire length, and to the outside of the pilot hole of the cutting dust generated by the biting of the tapping screw. Can be reliably discharged.

(II) Since the guide screw and the tapping screw are provided with a portion to be replaced only near the head, a smooth screwing speed can be obtained in the first half of the screwing process, and the screwing may not be possible during screwing. Absent.

(III) The required screw-in resistance can be obtained by selecting the length range of the interchanged portions provided near the heads of the guide screw and the tapping screw, and the screw-in resistance can be increased more than necessary. Therefore, the screwing resistance can be set within the range of screwing force of an electric screwdriver or the like.

(IV) Since there is no occurrence of idle rotation due to damage to the inner peripheral wall of the pilot hole, a firm fixation of the member to be tightened can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing a tightening screw of the present invention in a used state.

FIG. 2 (A) is an enlarged vertical sectional front view of a main part showing a state during screwing, and FIG. 2 (B) is an enlarged vertical sectional front view showing the same screwed state.

[Explanation of symbols]

 1 Shaft 2 Head 3 Guide screw 3a Large diameter part 4 Tapping screw 4a Small diameter part

Claims (1)

[Scope of utility model registration request] 1. A tightening screw for a hard member, wherein a guide screw and a tapping screw having a diameter larger than that of the guide screw are provided on the outer periphery of a shaft portion having a head at one end and a tip end at the other end. The guide screw and tapping screw have a constant diameter from the tip side to the middle of the head, and between the middle and the head, the guide screw is the diameter of the tapping screw, and the tapping screw is the diameter of the guide screw. Clamping screws for hard members, characterized by varying.