JP2004001103A - Thread forming tap - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thread forming tap with a stable lifetime by preventing the threads of the tap from being chipped. <P>SOLUTION: The thread forming tap 1 has a screw part 2 with a tapered bevel lead 3 whose tip is narrower and a parallel screw part 4 continuous to the bevel lead 3. By making the thread top cut height of the bevel lead 3 higher than the thread top cut height of the parallel screw part 4, the thread forming resistance in a part near the intersection point of the bevel lead 3 and the parallel screw part 4 where chipping of the screw threads may be easily generated is reduced, so that chipping of the screw threads in the thread forming tap is prevented. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a raised tap for plastic working of a female screw.
[0002]
[Prior art]
As shown in FIG. 7A, in the conventional tapping tap, the tapered thread portion of the biting portion 8 and the parallel thread portion 9 have the same thread crest cut height.
[0003]
Further, as shown in FIG. 7A, the conventional raised tap is a tapered thread portion of the biting portion 8 in which a root portion of the screw and an outer diameter portion are parallel to each other and have one taper angle α. ing.
[0004]
As a result, as shown in FIG. 7B, the conventional raising tap forms the female screw thread with a constant gradient from the screw thread 8a near the tip to the screw thread 8e near the parallel thread portion 9 with a constant gradient. The shape is such that D1 to D4 are sequentially raised toward the center of the screw hole.
[0005]
[Problems to be solved by the invention]
However, in the above-mentioned conventional raising tap, the threads 8a to 8e of the biting portion 8 sequentially increase the screw outer diameter in a constant amount as shown in FIG. As a result, both flanks of the thread of the biting portion 8 and the outer diameter of the screw drive the material to further raise the female screw, so that the volume of the material to be driven is increased by increasing the outer diameter of the screw, and the complete volume is increased. In the threads 8d and 8e near the parallel thread portion 9 that forms the thread shape, there is a problem that the bulging resistance is considerably larger than the threads 8a and 8b near the tip of the tap, and the threads are chipped.
[0006]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a raised tap having a stable life by preventing chipping of a thread of the tap.
[0007]
[Means for Solving the Problems and Their Functions and Effects]
In order to attain the above object, a tapping tap according to the present invention according to claim 1 has a threaded portion having a biting portion whose outer diameter portion is tapered and a parallel threaded portion continuous with the biting portion. In the tap, the height of the thread crest of the biting portion is larger than the height of the crest of the parallel thread portion.
[0008]
In addition, the tapping tap of the present invention according to claim 2 is a tapping tap having a threaded portion having a tapered biting portion having an outer diameter portion tapered and a parallel threaded portion continuous with the biting portion. The present invention is characterized in that, for one or both of the root portion and the outer diameter portion of the thread of the attached portion, the inclination angle of the portion near the tip is larger than the inclination angle of the portion near the parallel thread portion.
[0009]
Such a raised tap of the present invention has a thread crest cut height of a bite portion larger than a thread crest cut height of a parallel thread portion, and one or both of a root and an outer diameter portion of a screw of a bite portion. At least one of the inclination angle of the portion close to the tip and the inclination angle of the portion close to the parallel thread portion, thereby making the thread profile of the bite portion at least near the parallel thread portion of the bite portion. By reducing the cross-sectional area of the material raised by the flank of the thread near the parallel thread part of the bite part by making the flank coincide with or close to both flank of the thread of the parallel thread part to some extent, As the material near the parallel threaded portion of the bite is chased by the material near the parallel thread to reduce the amount of swelling of the thread of the internal thread, the tapered threaded portion of the bite becomes closer to the parallel thread. Can be obtained by gradual increase gradient of the resistance raised gradually increased by increasing the thread diameter to prevent chipping of the thread in the vicinity of the intersection of the parallel threads and chamfer Te.
[0010]
Embodiment of the present invention
The thread crest cut-off height of the tapping tap according to the present invention has a larger value in the tapered screw portion of the biting portion than in the parallel thread portion. The height of the thread crest cut-off in the tapered thread portion of the biting portion is appropriately in the range of about H / 8 to H / 3 (where H is the height of the peak of the screw in JIS, ie, both flank faces). ) Means the height from the lower intersection to the upper intersection of the straight lines that respectively match. In addition, the height of the thread crest at the tapered thread portion of the biting portion does not need to be constant within one raising tap.
[0011]
In addition, the inclination angle of the tapered thread portion of the biting portion in the tapping portion according to the present invention is greater than the inclination angle of the small diameter portion (the portion near the tip) of the large diameter portion (the portion near the parallel screw portion). The point of intersection between the inclined lines connecting the outer diameters of the screws and the point of intersection between the inclined lines connecting the roots of the screws is approximately 1/4 of the length of the biting portion from the center of the length of the biting portion. The range is appropriate. In addition, the inclination angles of the small-diameter portion and the large-diameter portion of the biting portion and the position of the intersection of the inclined lines are defined at the root and the outer diameter of the screw, respectively. The inclination angle of the root of the screw at the large diameter portion may be 0 degree. When the length of the biting portion is as short as 2 pitches or less, the inclination angle of the root of the screw at the small diameter portion of the biting portion may be 0 degree.
[0012]
【Example】
Hereinafter, five embodiments of the raised tap of the present invention will be described in detail with reference to the drawings. Each of these embodiments has the above-described functions and effects of the present invention.
[0013]
[First embodiment]
FIG. 1 is a front view showing the entire tapping tap according to the first embodiment of the present invention. FIG. 2A is an enlarged explanatory view of a biting portion of the tapping tap according to the first embodiment, and FIG. FIG. 4 is a diagram illustrating a raised form of the biting portion. The tapping tap according to this embodiment is a tapping tap 1 having a screw portion 2 having a biting portion 3 having an outer diameter portion tapered and a parallel screw portion 4 continuing to the tapping portion 3. By making the taper inclination angle θ2 of the outer diameter portion of the screw larger than the taper inclination angle θ1 of the root of the screw of the biting portion 3, the height of the thread crest of the biting portion 3 can be reduced. More gradually, the height of the parallel screw portion 4 approaches the peak cutout height.
[0014]
[Second embodiment]
FIG. 3A is an enlarged explanatory view of a biting portion of a raising tap according to a second embodiment of the present invention, and FIG. 3B is a drawing of a raised form of the biting portion. As in the previous embodiment, the tapping tap according to this embodiment is a tapping tap having a screw portion 2 having a biting portion 3 having an outer diameter portion tapered and a parallel thread portion 4 continuing to the tapping portion 3. 1, the taper of the root of the thread of the biting part 3 is set to be from the tip of the biting part 3 to the vicinity of the center of the length of the biting part 3, and thereafter, to the same root diameter as the parallel threaded part 4. The outer diameter of the thread of the biting portion 3 is tapered, and the entire biting portion 3 is tapered at a constant inclination angle, so that the height of the thread crest is gradually reduced. The effective diameter of the screw is the same as that of the parallel screw portion 4 from the vicinity of the center of the biting portion 3 to the vicinity of the parallel screw portion 4.
[0015]
[Third embodiment]
FIG. 4A is an enlarged explanatory view of a biting portion of a tapping tap according to a third embodiment of the present invention, and FIG. 4B is an explanatory diagram of a tapping form of the biting portion. As in the previous embodiment, the tapping tap according to this embodiment is a tapping tap having a screw portion 2 having a biting portion 3 having an outer diameter portion tapered and a parallel thread portion 4 continuing to the tapping portion 3. 1, the taper of the root of the thread of the biting part 3 is set to be from the tip of the biting part 3 to the vicinity of the center of the length of the biting part 3, and thereafter, to the same root diameter as the parallel threaded part 4. The outer diameter portion of the screw of the biting portion 3 has a small diameter portion (a portion near the tip) and a large diameter portion (a portion near the parallel screw portion) in the center of the length of the biting portion 3. Are provided at the intersections of the inclined lines of the taper, thereby making the height of the thread crest cut of the biting portion 3 larger than that of the second embodiment so as to make the crest height of the parallel screw portion 4 larger. And the effective diameter of the screw is from the center of the biting part 3 to the parallel thread part 4 Until it is the same as the parallel threaded portion 4.
[0016]
[Fourth embodiment]
FIG. 5A is an enlarged explanatory view of a biting portion of a tapping tap according to a third embodiment of the present invention, and FIG. As in the previous embodiment, the tapping tap of this embodiment is a tapping tap having a screw portion 2 having a biting portion 3 whose outer diameter portion is tapered and a parallel thread portion 4 continuing to the tapping portion 3. 1, the intersection of the tapered slope lines of the small diameter portion (the portion near the tip) and the large diameter portion (the portion near the parallel thread portion) is screwed near the center of the length of the biting portion 3 The outer diameter portion is provided at the position of point 5 and the root of the screw is provided at the position of point 6.
[0017]
[Fifth embodiment]
FIG. 6A is an enlarged explanatory view of a biting portion of a raising tap according to a third embodiment of the present invention, and FIG. As in the previous embodiment, the tapping tap according to this embodiment is a tapping tap having a screw portion 2 having a biting portion 3 having an outer diameter portion tapered and a parallel thread portion 4 continuing to the tapping portion 3. 1, a small-diameter portion (a portion near the tip) and a large-diameter portion (a portion near the parallel thread portion) near the center of the length of the biting portion 3 with respect to the root of the screw of the biting portion 3. An intersection 7 between the inclined lines of the tapered portion is provided. The outer diameter portion of the screw is formed such that the entire biting portion 3 is tapered at a constant inclination angle, so that the biting portion at the tip end of the biting portion 3 is formed. The height of the thread crest is made smaller than that at the center of the length of the screw 3, and the amount of change in the effective diameter of the screw is changed in two steps from the center of the length of the biting portion 3.
[0018]
As described above, the present invention has been described based on the illustrated examples. However, the present invention is not limited to each of the above-described embodiments, and the taper may be formed in an arc shape or the angle of the thread of the biting portion within a range not departing from the gist of the present invention. It goes without saying that various changes can be made, such as changing the character so that it does not excite in a similar shape.
[0019]
Further, it goes without saying that the present invention can be applied to a tap having an oil groove or a tap for performing surface treatment, similarly to the conventional one.
[Brief description of the drawings]
FIG. 1 is a front view showing a tapping tap according to a first embodiment of the present invention.
FIG. 2A is an enlarged explanatory view of a biting portion of the tapping tap of the first embodiment, and FIG. 2B is an explanatory diagram of a biting mode of the biting portion.
FIG. 3 (a) is an enlarged explanatory view of a biting portion of a raised tap according to a second embodiment of the present invention, and FIG. 3 (b) is an explanatory diagram of a raised form of the biting portion.
FIG. 4A is an enlarged explanatory view of a biting portion of a raised tap according to a third embodiment of the present invention, and FIG. 4B is an explanatory diagram of a raised form of the biting portion.
FIG. 5 (a) is an enlarged explanatory view of a biting portion of a tapping tap according to a fourth embodiment of the present invention, and FIG. 5 (b) is a drawing of a biting portion of the tapping portion.
FIG. 6A is an enlarged explanatory view of a biting portion of a tapping tap according to a fifth embodiment of the present invention, and FIG. 6B is an explanatory diagram of a biting form of the biting portion.
FIG. 7A is an enlarged explanatory view of a biting portion of a conventional tapping tap, and FIG. 7B is an explanatory view of a biting form of the biting portion.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Raised tap 2 Screw part 3 Biting part 3a First mountain 3b from the tip of biting part of the embodiment of the present invention 2nd mountain 3c from tip of biting part of the embodiment of the present invention 3d from the tip of the biting part 3d 4th from the tip of the biting part of the embodiment of the present invention 3e 5th from the tip of the biting part of the embodiment of the present invention 4 Parallel thread part 5 Screw of the biting part Intersection 6 between the slope lines at the bottom of the thread of the biting part Intersection 7 between the slope lines at the bottom of the thread of the biting part 8 Biting part 8a of the prior art 8 c from the tip of the bite portion of the prior art 3 c from the tip of the bite portion of the prior art 4 d 8 e from the tip of the bite portion of the prior art Fifth mountain from the end of bite 9 Parallel threaded part α Inclined angle θ1 of root of root and outer diameter part of screw at bite Inclination angle of the outer diameter portion of the section of the screw in the trough bottom screw of the tilt angle θ2 Full board portion of

Claims (2)

In a tapping tap having a threaded portion having a biting portion whose outer diameter portion is tapered and a parallel threaded portion continuous thereto,
A thread-raising tap characterized in that a thread crest height of the biting portion is larger than a thread crest height of the parallel thread portion. In a tapping tap having a threaded portion having a biting portion whose outer diameter portion is tapered and a parallel threaded portion continuous thereto,
Wherein one or both of the root of the screw and the outer diameter of the biting portion have a larger inclination angle at a portion closer to the tip than at a portion closer to the parallel thread portion, and a rising tap. .

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