JPS61152322A - Tap for loosening-suppressing female screw - Google Patents

Abstract

PURPOSE:To facilitate the work for a female screw having a large diameter and permit the mass production of loosening-suppressing nuts by reducing the cutting torque by varying the root angle of the intermediate screw part or the front screw part and the intermediate screw part of a tap. CONSTITUTION:The ridge angle theta1 of the front screw part 3 of a tap 1 is set larger than the root angle theta of a female screw 6. The inclination of the flank surface is formed into two surfaces by making the ridge angle theta2 of an intermediate screw part 4 smaller than the root angle theta of the female screw 6, and the dimension and the sectional shape of a rear screw part 5 is made equal to those of the female screw 6. When the female screw is worked into a nut blank 10 by the tap 1, the revolution of the tap 1 is stopped by a stopper 9. When a prepared nut 11 is screw-fitted onto a bolt, the flank surface interferes, and a frictional force acts to develop the superior loosening-suppressing function. In case of the screw having the deformed intermediate screw part 4, the cutting torque is small, and effective for the work of a female screw having a large diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a tap used to cut a locking female thread formed in a deformed thread groove in which a portion of the female thread to be machined is smaller than the root angle of the standard female thread. It is something.

2. Description of the Related Art The present inventor has already proposed a locking nut having a modified thread groove as described above in Japanese Patent Application No. 59-13947.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a tap suitable for mass production of the locking nuts disclosed in Japanese Patent Application No. 13947/1983.

In the structure of the invention, that is, the tap according to the present invention, the root width is almost the same as the groove width of the reference female thread 6 to be machined, and the extended intersection angle θ! is formed to be equal to or slightly larger than the root angle θ of the female thread 6, and the front thread portion 3 cuts the groove entrance portion of the female screw 6 following the chamfered portion 2, and the crest angle θ2 is the root angle θ of the female screw 6. It is characterized in that it has the female rear threaded portion 5 which is smaller in height h, and the pitch P of the series of threaded portions 3° 4.6 is formed to have the same dimension.

Effects of the Invention By using the tap of the present invention configured as described above, a female thread having a partially deformed thread groove with a small root angle can be processed very efficiently with one tap. Moreover, since the deformed thread groove is cut in two stages, and the standard thread groove is cut in three stages, the overall cutting torque is small, which is particularly advantageous when cutting large-diameter female threads. be.

Therefore, it is possible to mass-produce nuts having an excellent anti-loosening function at low cost, as disclosed in Japanese Patent Application No. 59-13947. Further, the tap according to the present invention has the advantage that it can be easily manufactured by grinding the threads of a commercially available standard tap.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings. 1st
The figure shows a tap 1 according to the present invention, and the threaded part is divided into three sections: a front threaded part 3 following the chamfered part 2, an intermediate threaded part 4, and a rear threaded part 5. 4 is provided in an area M (C) indicated by an arrow, which partially overlaps the front threaded portion 3 and the rear threaded portion 5 at the boundary areas on both sides.

As shown in FIG. 2 (a) K, the front threaded portion 3 has a root width that is almost the same as the groove width of the female thread 6 to be machined, which is indicated by a broken line, and an extended intersecting angle θ1 of the 7-rank surfaces on both sides. The groove entrance portion of the female thread 6 is cut so as to be larger than the valley angle θ of the female thread 6, following the chamfered portion 2.

As shown in FIG. 2 (b), the intermediate threaded portion 4 has a thread angle θ.
2 is smaller than the valley angle θ of the female thread 6 to be machined,
The thread height h is formed to be almost the same as that of the female thread 6, and its flank surface is constituted by two surfaces 3a and 4aa having different inclination angles, and is concave and larger than the flank surface of the female thread 6.

The rear threaded portion 5 has a single thread angle θ as shown in FIG.
3. The root width and the thread height h are the same as the female thread 6 to be machined, and the cross-sectional shape is the same as the female thread 6.

The pitches p of the series of threaded portions 3, 4.5 are all formed to have the same dimension. The flank surface 4 of the intermediate threaded portion 4 may be a curved surface that is more concave than the flank surface of the female thread 6, as shown in FIG.

When a female thread is machined into a 1° pilot hole of a nut blank using the tap 1 with the above configuration, the front thread part 3 first cuts the groove entrance part of the female thread, and then the intermediate thread part 4 cuts the root width and the thread height h. is the same as the female thread 6, and the valley angle θ2
A deformed thread groove 7 whose angle is smaller than the root angle θ of the female thread 6 is cut, and the deformed thread groove 7 cut by the intermediate thread part 4 is further processed into the same shape as the female thread 6 by the rear thread part 6. Therefore, the nut puller 10 is at a certain depth L from the bearing surface side.
When it enters the rear screw 6 until the end, the rotation of the tap 1 is stopped and the position of the nut blank 10 is regulated by the stopper 9. If the tap 1 is subsequently rotated in the opposite direction and removed from the nut blank 10, the fourth As shown in the figure, screw hole 12
The nut 11 is made up of a standard thread groove 6 formed on the flank face with a standard valley angle θ, and a deformed thread groove 7 formed on the flank face 8 with a valley angle θ2 smaller than the standard valley angle θ and convexly curved. can get. Therefore, the threads formed between the deformed thread grooves 7 have a larger cross-sectional shape than the threads formed between the reference thread grooves 6.

As shown in FIG. 5, the nut 11 obtained by K in this manner is such that when the male thread 13 of a bolt or the like is threaded, the thread 14 of the male thread 13 is deformed by the curved flank surface of the thread groove 7. As a result, a large frictional force acts between the flank surfaces of the thread 14 and the thread groove 7,
Demonstrates excellent anti-loosening function.

6 and 7 show an embodiment in which the front threaded portion 3, intermediate threaded portion 4 and rear threaded portion 5 of the tap 1 are provided completely independently. In this example, the extension intersection angle of both flank surfaces of the front threaded portion 3 is equal to the root angle θ of the reference female thread 6. With such a configuration, the cutting torque particularly due to the intermediate threaded portion 4 is reduced, which is effective when machining a large-diameter female thread.

[Brief explanation of the drawing]

Fig. 1 is a front view of a tap according to the present invention, Fig. 2 (a) to c) is an enlarged sectional view of the same main part, Fig. 3 is an enlarged sectional view of the main part of another embodiment, and Fig. 4 5 is a longitudinal sectional front view of a nut processed by the tap of the present invention, FIG. 5 is an enlarged sectional view of the main part of the same nut in use, FIG. 6 is a front view of a tap showing another embodiment, and FIG. ) or Nori is an enlarged cross-sectional view of the same essential parts. 1... Tap 2... Biting part 3... Front threaded part 4... Intermediate threaded part 5... Rear threaded part 6...Reference female thread 7...Deformed thread groove

Claims (1)

[Claims] 1. The root width (b) is almost the same as the groove width of the reference female thread (6) to be machined, and the extension intersection angle (θ_1) of the flank surfaces on both sides is the same as the groove width of the reference female thread (6) to be machined. A front threaded portion (3) that is formed to be equal to or slightly larger than the trough angle (θ) and cuts the groove entrance portion of the female thread (6) following the chamfered portion (2); An intermediate threaded portion (4) that is smaller than the trough angle (θ) of (6) and whose crest height (h) is almost the same as the female thread, and whose crest angle (θ_3), root width (b), and crest height (h) are the series of threaded parts (3), (4), (5) A tap for a female screw to prevent loosening, in which the pitch (p) is formed to the same size. 2. Claim 1, wherein the front threaded portion (3) and the intermediate threaded portion (4) are partially overlapped.
Tap as described in section. 3. The tap according to claim 1, wherein the front threaded portion (3), the intermediate threaded portion (4) and the rear threaded portion (5) are each provided independently.