JPH0295513A - Tap - Google Patents

Abstract

PURPOSE:To make the chamber of the present tape positive and to obtain accurate thread ridge and preferable finish surface by a method wherein, of adjacent lands, the chamfer initial portion of one land is made smaller in diameter than that of the other and also the thread effective diameter in the chamfer initial portion on the large diameter side is made smaller than that of the finish thread portion. CONSTITUTION:Each chamfer initial portion 5a of each chamfer portion 5 in three lands B, D and F is made smaller in diameter than each chamfer initial portion 4a of each chamber portion 4 in the other lands A, C and E. In the chamfer portion 4 of the large diameter side, that is, of the lands A, C and E, the thread of the initial portion 4a has the effective diameter (d1) smaller than the effective diameter (d2) of the post portion 4b and finish thread portion 6. As a result, the cutting edge flat portion of the chamfer initial portions 4a, 5b are made narrower in width, to thereby usually obtain the positive chamfer, thus preventing the inconvenience of enlarging the inner diameter of the thread. In addition, by cutting chattering and shape slide of the thread caused on the initial portions 4a, 4b during the chamfering operation with use of the cutting edge of the thread portion 6 located behind the initial portions 4a, 4b.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a tap, and more specifically, a NAND tap (including a hent shank tap) used when tapping a NAND material on an automatic nut tapping machine. ), it relates to an improvement in the tap screw structure that can be applied to a large effect.

[Prior art and its problems] When tapping a NAND using a tap, the tapped thread (hereinafter referred to as "work thread") often has irregular dimensions, poor thread shape, or poor finish on the thread flank surface. Problems may occur such as an enlargement of the inner diameter due to defects or unstable biting, and insufficient durability of the tap. It has long been known that the cutting characteristics of the threaded part have a large effect on the cutting characteristics of the threaded part, especially the size of the thread nozzle and the number of lands. Conventionally, attempts have been made to improve tap performance by variously changing the number of threads and the number of lands.

However, although increasing the number of threads improves sharpness, it has the disadvantage that the finish on the flank surface of the workpiece thread becomes chattering, and the finished thread is more likely to have defects due to dimensional expansion. On the other hand, when the second screw amount is decreased,
Although the finish and accuracy of the thread being cut improves, the sharpness decreases, so welding occurs to the cutting edge in a short period of time (built-up cutting edge).
This has the disadvantage of deteriorating the life of the tap.

On the other hand, increasing the number of lands improves the life, but when the nut material bites into the nut tap, the pressure acting on each cutting edge of the biting part is dispersed and becomes smaller, resulting in poor biting and This causes the inconvenience of causing a reaming action in the initial stage of attachment and enlarging the inner diameter of the nut material.

Therefore, a diameter-increasing stepped tap (also referred to as a tandem serial tap) has been proposed to address these drawbacks. As shown in FIG.
2, a finishing tap 13 is provided behind the first tab 12, and the threaded thread that has been roughly machined with the first tab 12 is finished continuously with the finishing tap 13. In this case, the thread number is increased to improve sharpness, while in the finishing tap 13, the number of thread numbers is reduced or no number is used to satisfy both the improvement of finishing accuracy of the workpiece thread and the extension of the tap life. ing.

However, in the diameter-increasing stepped tap, the first tab 12 and the finishing tap 13 are aligned on the same axis, so if the thickness of the nut material to be tapped is smaller than the distance between the two taps 12 and 13, the first tab 12 and the finishing tap 13 are arranged on the same axis. There is a problem that the movement of the nut becomes unstable when moving from the number tab 12 to the finishing tap 13, and a normal thread cannot be cut. That is, if the finishing tap 13 bites before the nut material passes the first tab 12, the biting first tab 12 acts as a guide to guide the finishing tap 13, so the nut Although the thread groove and the thread of the finishing tap 13 match,
If the nut material is thin and the finishing tap 13 bites after the first tab 12 has completely passed through the nut material, the finishing tap 13 is not guided by the first tab 12, so the first tab 12 is used to tap the nut. The thread groove of the finished nut and the thread of the finishing tap 13 are difficult to match, and the finishing tap 13
The feeding becomes unstable. As a result, the shape of the thread to be cut may be distorted or the inner diameter of the thread may become enlarged, resulting in a problem that the thread cannot be tapped normally.

This invention has the advantages of the diameter-increasing stepped tap described above, and also enables reliable biting regardless of the thickness of the nut, and can always provide accurate thread threads and a good finished surface. is intended to provide.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a tap having an even number of lands of at least four, in which the initial biting part of one of the adjacent lands is set to be higher than the biting initial part of the other land. The screw has a small diameter, and the effective diameter of the screw at the initial part of the chamfered portion of the land on the large diameter side is smaller than the effective diameter of the required finished screw.

[Effect]

In the tap configured as described above, among the plurality of lands, the chamfered portion of the land whose initial part of chamfering is on the large diameter side first bites into the nut material.

In this case, since the initial part of the chamfered part is smaller than the effective diameter of the finished thread, cutting using this initial part forms the thread inside the finished shape of the thread to be cut. This cutting corresponds to the cutting of the most tab in a conventional diameter-increasing stepped tap.

The thread formed in this way is then finished by cutting with the latter part of the chamfered part having a large effective diameter of each land and the cutting edge of the finishing thread part. As a result, the surface of the finished thread does not have chattering or deformation that occurs during biting, and the thread is finished with a good surface.

In addition, by reducing the effective diameter of the initial screw,
The width of the cutting edge flat part on the outer periphery of the thread at the initial stage is narrower than the width of the cutting blade flat part at the initial part of the chamfer in a conventional finishing tap whose effective diameter is the same as the effective diameter of the finishing thread. During the biting, only the biting portions of half of the lands among the plurality of lands bite into the nut material, so that the tap bites into the nut material reliably. Therefore, the reaming effect is eliminated, and the inner diameter of the thread to be cut can be prevented from expanding.

〔Example〕

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

As shown in FIG. 7, the tap of the embodiment is provided with a tap portion 2 at the tip of the shank 1, which is a combination of the first tab and the finishing tap, and the tap portion 2 is as shown in FIG. Like 6 lands A and B.

It is formed by C, D, and ESF.

Further, as shown in FIGS. 1 to 5, the initial chamfering portions 5a of the chamfering portions 5 in three lands B, D, and F out of the six lands are similar to those in other lands A, C, It is lower than the initial biting part 4a of the biting part 4 at E, and
In the chamfered portions 4 in lands A, C, and H on the large diameter side, the threads in the initial portion 4a are formed with an effective diameter d smaller than the effective diameter dt of the threads in the latter portion 4b and the finishing thread portion 6. ing.

This will be explained with respect to the chamfered portions 4.5 of land A and land B. As shown in FIG. 5, the chamfered portion 4 of land A
consists of an initial part 4a and a latter part 4b which is continuous with the parallel thread of the finishing thread part 6, and the outer circumferential surface of the threads A5 to A7 of this latter part 4b is the effective diameter d of the finishing thread,
It is formed into a tapered shape with reference to . On the other hand, the outer circumferential surface of the thread Al-A4 of the initial portion 4a is tapered with respect to an effective diameter d smaller than the above-mentioned effective diameter d2. In this way, if the radius vector d of the thread in the initial part 4a is made smaller than the effective diameter d2 of the finishing thread, the width of the cutting edge part 3 on the outer periphery of the thread in the initial part 4a will be the same as the effective diameter d2 up to the initial part. It will be narrower than if it were formed.

That is, if the initial biting part 4a is formed with the effective diameter d2 of the finishing swarf as shown by the broken line in FIG. Since the part near the root of the screw becomes the threaded part of the cutting edge, the width of the threaded part becomes wider, which has the disadvantage of being larger than that formed with the effective diameter d2 (shown by the solid line).

In this structure, the other initial biting parts are large-diameter runts C and E.
The same applies to

On the other hand, in the chamfered portion 5 in land B, the initial portion 5a is inclined at a larger angle than the inclination of the latter portion 5b, and the diameter of the threads B3 and B4 of the initial portion 5a is
, H (line indicated by 4' in FIG. 5) is set smaller than the diameter of the initial part of chamfering. This also applies to other lands D and F where the initial part of biting is on the small diameter side.

In addition, the threads from the latter parts 4b and 5b of the chamfered parts 4.5 to the finishing thread part 6 in each land A, B, C, D, E, and F are formed based on the effective diameter d2 of the finishing thread. However, the threads on each land are arranged in the length direction of the tap so that when the tap is rotated, the next thread cutting edge cuts the nut material in sequence along the direction of rotation. They are formed with their phases shifted by a predetermined amount.

This embodiment has the above-mentioned structure.Next, the erecting action using this tap will be explained with reference to FIG.

(a) The initial biting cutting edges A1 and C1 have a slightly smaller diameter than the pilot hole of the NAND, and serve as a guide and do not perform any cutting action.

That is, the tap first bites into the nut material with the cutting edge E1, then A2 bites, and then C2, E2, and A.
3. Cutting is performed at C3. At this position, lands B, D,
, F is lower (smaller diameter) than A, C, and E, so it hasn't hit the nut yet.

Moreover, since the cutting edges Al-A4, C1 to C4, and E1 to E4 have a small effective thread diameter, the threads are formed inside the finished thread shape of the thread to be cut. In addition, at the beginning of biting, the tap is not firmly biting into the nand, so the thread shape of the workpiece is likely to collapse in an unstable state. does not affect. (If there are four lands, the tip of the tap is used as a guide part, and by making this part the same diameter for all lands, it is possible to prevent the nut from wobbling.) (b) Chamfered mid-term cutting edge C3 will bite, and then the cutting edge of D3 will bite.

Below, E3→F3→A4-=B4→C4→D4→E4→
It bites in the order of F4. In addition, since the cutting edges of lands F1B and D have a finish thread shape (the outer periphery is lower than the finish thread), the cutting edge has a finish thread shape. Land ASC at this position.

When cutting E, the tap is firmly biting into the nut, so the shape of the thread being cut does not deteriorate.

Next, the biting progresses as A5 → B5 → C5 → D5 → E5 → F5, but since A5, C5, and E5 are the joints from the early part to the latter part of the chamfered part, only one flank has a finished thread shape. , but this is supplemented by 85, D5, and F5.

(C) Late eating period After A6, the action is similar to that of a normal tap.

As a result of the above-mentioned actions, chatter and deformation of the thread shape at the initial part of the chamfering do not remain on the final finished surface, and the thread surface is finished into a beautiful surface.

In the above case, among the chamfered portions 4.5 of the six lands, half of the lands B and the chamfered initial portions 5a of the chamfered portions 5 in DSF are replaced with the other lands A, C, and E. By making the chamfering part 4 lower than the chamfering initial part 4a in , when the nut material bites into the tap, the chamfering initial part 5a on the small diameter side does not bite, and the chamfering initial part 4a on the large diameter side does not bite.
Only the fish will be eaten.

For this reason, the number of lands is similar to the conventional nut tap with three lands, and since the cutting edge part 3 at the initial biting stage is narrow, an even better biting effect can be obtained, and the nut material can be secured securely. can be fed to Therefore, there is no reaming action at the initial stage of biting, and the inconvenience of enlarging the inner diameter of the thread to be cut can be prevented.

Note that in the above embodiment, half of the lands B, D, and F
The chamfer initial part 5a in the nut tap is made lower than the chamfer initial part 4a in the other lands A, C, and E by scraping the outer peripheral surface, but generally, the chamfer part in the nut tap is provided with a second chamfer. Therefore, the height can also be lowered by shaving the rake faces of the chamfered portions of half of the lands.

On the other hand, FIG. 8 shows another embodiment, and is an enlarged view of the land portion on the large diameter side at the initial biting portion. In this example, the initial part 7a of the biting part 7 of the land is
The thread is formed of a tapered thread that gradually expands from the tip to the rear end, and the rear end of the reference line S of its effective diameter is the same as or smaller than the effective diameter d2 of the finished thread. In this way, the width of the cutting edge part 8 on the outer circumference of the initial part 7a becomes narrower than that of the part 3 of the previous embodiment, and a good biting effect can be obtained.

In the case of the above embodiment, the case where the number of lands is 6 was explained as an example, but the number of lands may be an even number of 4 or more. For example, if there are 8 lands, 4
The initial part of the chamfering part in the land of the book is made lower than the initial part of the chamfering part of the other remaining lands. In either case, the low chamfer parts and the high chamfer parts are arranged alternately in the circumferential direction to prevent the nut material from being eccentric or tilted with respect to the nut tap at the beginning of the nand material's chamfering.

〔effect〕

As described above, in the present invention, the initial part of the chamfered part in one of the adjacent lands is made smaller in diameter than the initial part of the chamfered part in the other land, and the larger diameter side Since the effective diameter of the thread at the initial part of the land is smaller than the effective diameter of the finished thread, the width of the cutting edge part at the initial part of the land can be made narrower, and a reliable thread can always be obtained. In addition to preventing the problem of the inner diameter expanding, the chattering and deformation of the threads that occur at the initial part of chamfering can be scraped off with the cutting edge of the threaded part located behind the initial part, making it a good product. You can get a good finished surface.

[Brief explanation of drawings]

FIG. 1 is a right side view of the embodiment according to the present invention, the second is a left side view of the same as above, and FIG. 3 is a cross-sectional view taken along line [-1] of FIG.
Figure 4 is a cross-sectional view taken along the I-II line in Figure 1, Figure 5 is a vertical cross-sectional side view of each of the lands A, B, C, D, E, and F in the same manner, and Figure 6 is a cross-sectional view of the lands A, B, C, D, E, and F. A diagram schematically showing the notch configuration of
FIG. 7 is a perspective view showing the tap of the same embodiment as above, FIG. 8 is a longitudinal sectional side view of the main part of another embodiment, and FIG. 9 is a side view showing a conventional diameter-increasing stepped tap. 2...Tap part, 3.8...
Cutting edge part, 4.5.7... Biting part, 4a, 5a, 7a... Initial biting part, 4b, 5
b, 7b... Late part of chamfering, 6... Finished threaded part, 9... Reference line of effective diameter, A...
B, CS D, E, F...Land, dLd2・
...Effective diameter.

Claims (2)

[Claims] (1) In a tap with at least four or more even lands, the initial biting part of one of the adjacent lands has a smaller diameter than the initial biting part of the other land, and the land on the larger diameter side A tap characterized in that the effective diameter of the thread at the initial part of the chamfer is smaller than the effective diameter of the required finishing thread. (2) The tap according to claim 1, wherein the thread at the initial biting portion of the land on the large diameter side is a tapered thread that widens from the tip to the rear end.