JPH0642515A - Screw - Google Patents

Abstract

PURPOSE:To provide a screw which can fix a plurality of members in a close by attached condition. CONSTITUTION:A thread 5 is formed around the peripheral surface of a shaft body 2. Each pitch of the thread 5 is gradually increased toward a tip of the shaft body 2. That is, P1>P2>P3... Pn. In a screw 1, the thread of the larger pitch is going to proceed faster than the thread of the smaller pitch, so that tensile strength toward the tip is generated on the thread 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw for fixing wood or gypsum panels.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional screw is provided with a large-diameter head 12 at the rear end of a shaft body 11 having a sharp tip, and a peripheral surface of the shaft body 11 on the tip side. Pitch thread 1
3 is formed, and when it is screwed into wood or the like, it is screwed at the same feed rate per rotation due to the pitch of the thread 13 thereof.

By the way, when a plurality of members A and B such as wood are fixed by using screws, when one member A penetrates into the other member B, one member A is changed due to a change in resistance applied to the screw. It may come up. However, in the above-mentioned conventional screw 10, when the screw is screwed into the other member B next time, the screw threads 13 are always fed to the both members A and B at the same pitch, so that the above-mentioned floating occurs. There is a case where both members A and B are fixed without being completely adhered to each other without being corrected until the end.

The present invention has been made in view of the above problems of the screw, and an object of the present invention is to provide a screw which can firmly fix and fix a plurality of members.

[0005]

In order to solve the above-mentioned problems, the screw of the present invention is provided with a large-diameter head at the rear end of a shaft body having a sharp tip, and the shaft side peripheral surface of the shaft body is provided. In the screw having the thread, the pitch of the thread is gradually increased toward the tip of the shaft body.

[0006]

In the above structure, the thread on the front end side having a large pitch tries to advance faster than the thread on the rear end side, and the thread on the rear end side is pulled to the tip side,
Lifting between the plurality of members is prevented.

Further, since tension is generated between the screw threads on the front end side and the rear end side, each screw thread bites into the member in a state where a preload is applied, so that the screw is prevented from loosening or coming off. .

[0008]

EXAMPLE FIG. 1 shows an example screw. This screw 1
A head portion 3 having a diameter larger than that of the shaft body 2 is provided at the rear end of the cylindrical shaft body 2 having a sharp tip, and a driver groove 4 such as a cross or a single character is formed in the head 3. .

Further, screw threads 5 are formed on the peripheral surface of the shaft body 2 almost entirely, and each pitch P ₁ , P ₂ , P ₃ , ..., P _n of the screw threads 5 is Increase gradually from the rear end of the body 2 toward the front end (P ₁ > P ₂
> P ₃ ......> P _n) are formed.

The screw 1 of the embodiment having the above structure
2 is inserted into a plurality of members A and B as shown in FIG. 2 and screwed in, the thread on the front end side with a large pitch tries to enter faster than the thread on the rear end side with a small pitch.
Due to the reaction force applied to the threads 5 from the surrounding material, a tensile force F toward the tip side is always generated in each thread 5. Due to this tensile force F, both members A and B are brought into close contact with each other between the screw threads 5, and the floating of both members is prevented.

Further, when the screw 1 is embedded in the members A and B, the tensile force F is maintained between the screw threads 5 on the front end side and the rear end side. 5 is as if a preload was applied, effectively preventing the screw 1 from loosening or coming off.

The screw thread 5 does not have to be provided on the entire shaft body 2, and may be formed within the range of the length for connecting both members A and B.

Further, the pitches P ₁ , P ₂ ,
It suffices that P ₃ , ..., P _n are slightly different from each other, and the amount of change in the pitch is appropriately set based on the size of the pitch, the diameter of the shaft body 2, the length, and the like. For example,
When the pitch P _n of the thread 5 on the rear end side of the shaft body 2 is 1 to 3 mm and the diameter of the shaft body 2 is 3 to 5 mmφ, the pitches P ₁ , P ₂ ,
The change amount of P ₃ , ..., P _n is 1 to 10% of the pitch P _n .
It is desirable to set within the range. By setting in the above range, it is possible to reduce the deformation of the shape of the thread inside the member due to the difference in pitch when the screw bites into the member, and to obtain a high holding force. Further, within the above range, it is possible to mold a molding die for rolling a screw.

[0014]

As described above, in the screw of the present invention, the pitch of the screw threads is different, and each screw thread is pulled toward the tip end side, so that it is possible to prevent floating between the screwed members,
It is possible to obtain a tight fixing of the members.

[Brief description of drawings]

FIG. 1 is a front view showing a screw of an embodiment.

FIG. 2 is a sectional view showing an operating state of the above.

FIG. 3 is a sectional view showing an operating state of a conventional screw.

[Explanation of symbols]

 1 Screw 2 Shaft 3 Head 4 Driver Groove 5 Thread

Claims (1)

[Claims] 1. A screw in which a large-diameter head is provided at the rear end of a shaft body having a sharp tip, and threads are formed on the tip-side peripheral surface of the shaft body. A screw characterized in that the screw gradually increases toward the tip of the screw.