JP2777100B2 - Raised tap with internal finishing blade - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tapping tap for forming an internal thread by plastic deformation, and more particularly, to an inner diameter capable of performing high-efficiency processing even on a cast hole of an aluminum alloy and obtaining a long life. It relates to a raised tap with a finishing blade.

[0002]

2. Description of the Related Art Protrusions projecting in the radial direction and relief portions having a small diameter following the protruding portions are provided alternately along the direction in which the screw advances in such a manner as to be continuous at substantially equal angular intervals around the axis. It has a threaded portion, and is formed into a type of a tapping tap which forms an internal thread by plastically deforming the protrusion by making the protrusion penetrate into a surface layer of a prepared hole provided in the workpiece. Taps with internal finishing blades have been proposed to finish steel. For example, the tap described in Japanese Utility Model Publication No. 60-15623 is the tap.

[0003] According to such a raised tap with an inner diameter finishing blade, the peak of an internal thread, that is, the shape of an imperfect crest generated in the internal diameter of an internal thread is removed, or a tapered cast hole or the like is formed. In the case where the size of the prepared hole previously formed in the workpiece is a small hole less than the control limit,
There is an advantage in that the work to be plastically flowed has a large surplus and the surplus loses the place to go and causes an excessive torque, thereby preventing breakage of the tap or improving the inner diameter accuracy of the internal thread. .

[0004]

In the above-mentioned conventional tapping tap with an inner diameter finishing blade, the highest portion of the root diameter of the external thread portion of the tap is formed by the protrusion (the highest portion of the external diameter of the external thread portion). (Lobe), and a groove is provided for making the highest part of the valley diameter a cutting edge.

[0005] However, in general, when forming the external thread portion of the raised tap, the thread and the root of the external thread portion are formed by a process called thread grinding in which the thread is ground by a grinding wheel formed on the outer peripheral surface. It is common to process both at the same time.However, with the conventional tapping with internal diameter finishing blade as described above, the uneven shape of the peak and valley of the male thread is not synchronized in the circumferential direction, and it is manufactured. In doing so, it is necessary to grind individually. This not only complicates the manufacturing process, but also makes it difficult to control the dimensions of the thread.On the other hand, if high dimensional accuracy is to be obtained, the accuracy of the entire male thread must be increased, and high processing technology and There is a disadvantage that manufacturing costs are required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to control the dimensional dimension of a thread by basically forming a male thread in a simple process similar to the conventional one. It is an object of the present invention to provide a raised tap with an inner diameter finishing blade which is easy to manufacture and reduces the manufacturing cost.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the gist of the present invention is that a projecting portion projecting in the radial direction and a small-diameter relief portion following the projecting portion extend along the screw advancing direction. Male threads provided along a thread having a uniform height so as to alternately and continuously at a predetermined angular interval around the axis, and a projection of the male thread is provided on the workpiece. In a raising tap which forms a female screw by being plastically deformed by being bitten into a surface layer portion of a prepared hole, a root diameter of a part of the protruding portion of the protruding portion located within one lead of the male screw portion is changed to another value. The protrusion has a diameter larger than the bottom diameter of the protrusion, and a portion of the protrusion is removed to the bottom, and a groove for forming a cutting edge is provided in a portion corresponding to the bottom of the removed portion. is there.

[0008]

According to the above configuration, one thread at the male thread portion can be obtained.
Since some of the protrusions in the protrusions located in the lead are removed to the bottom, and a cutting edge is formed in a portion corresponding to the bottom of the removed portion, the thread of the external thread portion is formed. Of the meat that is plastically deformed due to the bite, the excess thickness that has moved inward from the valley diameter is removed by the cutting edge, so that an internal thread having a predetermined accuracy can be easily roll formed. In the tapping tap with the inner diameter finishing blade of the present invention, the maximum diameter of the valley bottom is not formed in the relief portion following the protrusion of the male screw portion, but the uneven shape of the ridge and the valley bottom is synchronized in the circumferential direction. Therefore, by a process called thread grinding in which the thread is ground by a grinding wheel formed on the outer peripheral surface, the peaks and valleys of the external thread can be formed simultaneously and with high precision. Dimensional control becomes extremely easy, and the manufacturing cost is reduced.

[0009]

Another aspect of the present invention, preferably, a predetermined number excluding one, which is a divisor of the number of protruding portions per lead of the male screw portion, is one cycle. Sometimes, the protrusion at the position corresponding to the one cycle is removed to the valley bottom. As a result, the projections to be removed are continuously adjacent in the axial direction.

[0010] Preferably, the external thread portion has a bite portion whose outer diameter becomes smaller toward the distal end side and a complete outer shape formed continuously from the base end side of the bite portion. The diameter of the inner diameter finishing blade at least in the complete ridge is made to match the inner diameter of the internal thread.
In this way, at least in the complete ridge, the excess thickness which is plastically deformed by the biting of the external thread and which has moved inward from the root diameter is deleted by the cutting edge, and the high-precision internal thread is removed. Is roll formed.

[0011] Preferably, the male thread portion has a thread formed by one thread grinding step, and the thread height of the male thread portion is uniform at least in the complete thread portion. In the complete crest, the diameter of the root of the unremoved protrusion is smaller than the diameter of the root of the removed protrusion, that is, the inner diameter of the internal thread to be formed.
In this way, when the female screw is raised, the excess thickness formed on the top of the thread of the female screw is suitably removed.

Preferably, the portion in which the protruding portion adjacent in the axial direction is removed to the valley is formed over the entire area of the male screw portion in the axial direction. Preferably, the groove is formed over the entire area of the biting portion in the axial direction. With this configuration, the excess thickness that has moved inward from the cutting edge is cut in the entire biting portion where the rolling load is the largest, so that there is an advantage that the rolling torque is further reduced.

Preferably, the groove is formed on the complete ridge and the complete ridge side of the bite, and the groove has an oil groove following the groove. Formed up to the tip of In this way, even when the groove is not formed in the entire axial direction of the biting portion because the groove is shallow, there is an advantage that the cutting oil is suitably supplied over the entire axial direction of the biting portion with a large rolling load. is there.

Preferably, at least the projecting portion and the cutting edge formed on the biting portion are formed in a circumferential direction of a relatively durable metallic material such as tool steel, high-speed steel, or alloy steel. Is formed of a wear-resistant material such as a cemented carbide or an ultra-high-pressure sintered body fixed to a part of the material. With this configuration, since the protrusion and the cutting edge with the largest frictional load are made of a wear-resistant material such as a cemented carbide or an ultra-high pressure sintered body, the accuracy of the rolled screw can be obtained over a long period of time. In comparison with the case where the whole body is made of a cemented carbide, there is an advantage that breakage of the rolled screw is prevented.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a tapping tap (hereinafter referred to as a tapping tap) 10 having an inner diameter finishing blade according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 2, which is cut along the root of the thread for easy understanding. The above raised tap 10 is
At its base end, it has a shank part 12 to be gripped by a chuck device (not shown), and at its tip part it has an external thread part 14 for rolling female threads.

The external thread portion 14 has a biting portion 16 whose outer diameter becomes smaller toward the distal end side, and a complete mountain portion having a constant outer diameter following the base end side of the biting portion 16. 18. The shape of the full thread portion 18 is substantially the same as the shape of the thread and valley of the internal thread to be roll-formed on the surface layer of the prepared hole (not shown) of the workpiece. At the surface of the internal thread and generate thrust in the screwing direction.

The external thread portion 14 has a polygonal cross section having outwardly curved sides, in this embodiment a substantially rectangular cross section having four outwardly curved sides, and has a uniform height from the bottom. Crests are formed along the windings of the predetermined lead angle. The thread has four protrusions 20 and 20 ′ protruding to the outer peripheral side in one cross section, and reliefs 22 and 2, each of which has a small diameter continuous with the protrusions 20 and 20 ′.
2 ′, the male screw portion 14 is provided with radially protruding protrusions 20, 20 ′ and small-diameter relief portions 22, 22 ′ following the protrusions 20, 20 ′. They are provided so as to alternate with each other along the advancing direction of the screw, that is, along the winding line and at a predetermined angle around the axis, that is, at equal angular intervals of 90 ° in this embodiment. Further, in the present embodiment, the protruding portions 20, 20 'are provided so as to be continuous at equal angular intervals of 90 [deg.] Along the winding line, and as a result, as shown in FIG. Are adjacent to each other every one lead (one rotation) of the winding wire.

A part of the plurality of protrusions 20 and 20 'formed along the above-mentioned wrapping line,
Are removed by surface grinding until the axially adjacent protrusion 20 'reaches the root of the thread. That is, a plurality of protrusions 20 formed along the wrap line,
When a predetermined number excluding 1 (2 in the present embodiment) which is a divisor of the number per lead of 20 'is defined as 1 cycle, the protruding portion (1 in this embodiment) at a position corresponding to the 1 cycle. Every other protruding portion) 20 'is removed to the bottom of the valley.
As a result, in the cross section of the complete crest portion 18 shown in FIG. 2, the grinding contacting the maximum diameter position D of the valley bottom of the protruding portion 20 'and orthogonal to the radius OD connecting the maximum diameter position D of the valley bottom and the rotation center O. Surface A is formed.

On the ground surface A formed by removing the protruding portion 20 ', a portion corresponding to the valley bottom and at the maximum diameter position D is provided for finishing the inner diameter of the female thread to be rolled. In order to form the cutting edge 24, a groove 26 having a semicircular cross-sectional shape parallel to the axis of the tapping tap 10 is provided. Here, the outer shape of the protrusion 20 that is not removed is smaller in diameter than the outer shape of the protrusion 20 ′ that has been removed. That is, the rotation center of the raising tap 10 is O, the maximum diameter position of the projection 20 is B, and the projection 2 is
Assuming that the valley bottom position of 0 is E, the mutual radial dimension is set as follows.

That is, since the thread of the complete thread portion 18 is formed by one screw grinding step, it has the same height, and the thread diameter (2) of the projection 20 which is not removed in the thread grinding step. × OB) so as to match the root diameter of the female thread to be rolled, and so that the root diameter (2 × OD) of the protrusion 20 ′ matches the inner diameter (peak diameter) of the female thread to be rolled. Since the thread is formed, the diameter of the protrusion and the diameter of the root of the protrusion 20 that has not been removed (2 × O
E) is smaller than the peak diameter and the valley bottom diameter (2 × OD) of the removed protrusion 20 ′.
Therefore, since the cutting edge 24 is formed by the groove 26 at the minimum diameter position in the grinding surface A having the same diameter as the root diameter (2 × OD) of the protruding portion 20 ′, the diameter of the rotation locus of the cutting edge 24. That is, the root diameter (2 × OD) of the protruding portion 20 ′ is made to match the inner diameter of the female screw to be roll-formed.

Next, a method of manufacturing the building tap 10 configured as described above will be described below. First, in the thread grinding process, a bar made of a relatively durable metal material such as tool steel, high-speed steel, alloy steel, etc. The thread is ground by using a grinding wheel formed on the outer peripheral surface of the mountain, so that the tip of the tap body has a substantially square cross-section with four sides curved outward as shown in FIG. Male thread 1
4 is formed, and four threads 20, 20 'protruding to the outer peripheral side are formed on the thread along the helical wire having a predetermined lead angle of the external thread section 14, and the projections 20, 20' are continued. In addition, relief portions 22 and 22 'having a smaller diameter are formed. The height from the root of the thread is equal to the height of the thread formed on the outer peripheral surface of the grinding wheel, and is at least uniform at the complete thread portion 18.

In such a screw grinding step, for example, the material is moved along an arc around the center of curvature of one side of the square while being held at four positions at every 90 ° around the axis of the material. In the process, the outer peripheral surface of the round bar-shaped material of the tapping tap 10 is ground by the rotating grinding wheel. As a result, the root diameter (2 × OD) of the protruding portion 20 ′ matches the inner diameter (peak diameter) of the female screw to be formed by raising, and the crest diameter (2 × O
The thread of the raised tap 10 is formed such that B) matches the root diameter of the internal thread to be formed by the raised.

Next, in the protruding portion removing step, every other protruding portion 20 ′ of the protruding portions 20, 20 ′ extending along the helical winding is moved in the direction in which Then, the ground surface A is formed by performing surface grinding in a direction parallel to the axis of the raising tap 10 until the valley bottom is reached, thereby forming the ground surface A as shown in FIG.

In the groove forming step, the groove 26 is formed as shown in FIG. 2 by grinding on the rotation direction side of the line indicating the minimum diameter position of the grinding surface A, thereby indicating the minimum diameter position. A cutting edge 24 is formed along the line. In this groove forming step, a grinding wheel provided with a ground surface cross-sectional shape similar to the cross-sectional shape of the groove 26 on the outer peripheral portion is used.

By using the tapping tap 10 according to the present embodiment configured as described above, the rolling proceeds as shown in FIG. 5, and a highly accurate internal thread 32 is formed on the surface of the prepared hole of the workpiece 30. Is obtained. That is, when the biting portion 16 of the raising tap 10 is screwed into the surface layer of the prepared hole of the workpiece 30 shown in FIG.
When the plastic deformation is started as shown in FIG. 5 (b) and the complete ridge 18 is further advanced following the biting portion 16, the plastic deformation proceeds as shown in FIG. 5 (c). Female thread 3
A surplus 34 is formed in the inner circumferential direction from the top of the second crest 2, and as shown in FIG.
4 is removed. Therefore, a female screw 32 having a high inner diameter dimensional accuracy is formed even for a pilot hole whose dimensions are difficult to control, such as a tapered hollow hole provided in a die-cast light alloy member known as AC2C or the like. is there. For example, the standard pilot hole size for a female thread of 6H is 1
1.34 mm to 11.41 mm is recommended, whereas the above tapered cast hole has a mouth diameter of 11.30 mm but a depth of 11.30 mm.
The exit diameter of 18mm is 10.80mm.

As described above, the rising tap 1 of this embodiment is
0, a portion of the protrusion 20 that is adjacent to the protrusion 20 'in the axial direction is removed to the bottom, and a female screw 3 to be formed in a portion corresponding to the bottom of the removed portion is formed.
Since the cutting edge 24 having the same inner diameter and the same outer diameter as that of the second thread 2 is formed, the excess thickness of the meat that is plastically deformed by the biting of the thread of the external thread portion 14 has moved inward from the root bottom maximum diameter. Since the cutting edge 34 is removed by the cutting edge 24, the female screw 32 with high precision is formed by rolling, and the rolling load is reduced even for a pilot hole having an inner diameter smaller than the control limit, thereby causing breakage due to excessive torque. Is also suitably prevented.

Then, when manufacturing the raised tap 10 with the inner diameter finishing blade of the present embodiment, the projecting portion 2 of the male screw portion 14 is formed.
Instead of forming the maximum diameter of the valley bottom in the relief portions 22 and 22 ′ following 0 and 20 ′, the threads are formed on the outer peripheral surface because the unevenness between the ridge and the valley is synchronized in the circumferential direction. By a process called thread grinding in which a grinding wheel is used for grinding, the peaks and valleys of the male screw portion 14 can be formed simultaneously with high accuracy and efficiency, and the dimensional control of the male screw portion 14 becomes extremely easy and high. The precision tapping tap 10 can be easily manufactured, and the threading tap 10 can be manufactured at low cost.

According to the conventional tapping tap 40 with an internal diameter finishing blade, as shown in the cross section of the threaded portion in FIG. 6, the projecting portion 42 is formed on the thread of the male threaded portion and also protrudes from the root of the valley. A portion 44 is formed, and a groove 46 is formed between the thread protrusions 42 so that a cutting edge 48 having a maximum diameter at the root is formed at the protrusion 44 at the root. For this reason, the uneven shape of the thread and the root is not synchronized in the circumferential direction.
Since it is impossible to form a screw thread by a single screw grinding process of grinding with a grinding wheel formed on the outer peripheral surface, it is necessary to individually perform grinding using a plurality of types of screw grinding processes. In addition to complicating the process, it also makes it difficult to control the thread dimensions, but if high dimensional accuracy is required, the accuracy of the entire male thread must be increased, requiring high processing techniques and manufacturing costs. The disadvantage was that

Next, another embodiment of the present invention will be described. In the following description, the same parts as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 7 shows a cross section of a male thread portion of a raising tap 50 according to another embodiment of the present invention. In the drawing, a wear-resistant material 52 such as a cemented carbide or an ultra-high pressure sintered body is fixedly embedded in a portion corresponding to the protruding portion 20, and the protruding portion 20 having the largest rolling load or the cut is cut off. The durability of the blade 24 is enhanced. A round bar-shaped material 54, such as tool steel, high-speed steel, or alloy steel, which is cut to a predetermined length as shown in FIG. A plurality of the wear-resistant materials 52 are spirally embedded on the outer peripheral surface of the round bar-shaped material 54, and the protrusions 20, 2 and 2 are embedded in the embedded portions of the wear-resistant material 52.
The thread grinding is performed so that 0 'is formed. As a result, the protrusions 20 and 20 'for each lead are spirally adjacent in the axial direction, and the ground surface A and the groove 26 are also formed in a spiral shape. According to the present embodiment, the projection 20 and the cutting edge 24 having the largest frictional load
Is made of a wear-resistant material 52 such as cemented carbide, so that the accuracy of the rolled screw can be obtained over a long period of time, and the breakage of the rolled screw is smaller than when the whole body is made of a cemented carbide. This has the advantage of preventing

FIG. 9 shows a cross section of a male thread portion of a raising tap 60 according to another embodiment of the present invention. In the figure, the cross section of the male screw portion shows a substantially regular hexagonal shape having six sides curved outward, and the protrusions 20 are provided at equal angular intervals of a central angle of 60 °. Further, as in the embodiment of FIG. 2, every other protrusion 20 'of the protrusions 20 provided along the wrapping line is removed to correspond to the valley bottom of the protrusion 20'. The groove 26 is formed so that the portion, that is, the maximum portion of the valley bottom diameter becomes the cutting edge 24.

FIG. 10 shows a cross section of a male thread portion of a raising tap 62 according to another embodiment of the present invention. In the figure, the protrusions 20 are arranged at equal angular intervals of 120 ° around the axis.
Is provided, and the protrusion 2 is provided between the pair of protrusions 20.
0 ′ is formed, and the groove 26 is removed so that the protruding portion 20 ′ is removed to the valley bottom at that position and the portion corresponding to the valley bottom of the protruding portion 20 ′, that is, the maximum portion of the valley bottom diameter becomes the cutting edge 24. Is formed.

FIG. 11 is an enlarged view of a main part of a raising tap 64 according to another embodiment of the present invention. In the drawing, the groove 26 is formed over the entire area in the axial direction of the complete peak portion 18, but continues to a part of the biting portion 16 on the complete peak portion 18 side, and ends there.
In the present embodiment, the depth of the groove 26 is smaller and the taper angle of the biting portion 16 is larger than in the embodiment of FIG. 1, but the same applies to only one of them. In this embodiment, the width of the oil groove 66 from the end of the groove 26 to the tip of the biting portion 16 is smaller than the width of the groove 26 and has a rectangular cross section.
Are formed. The oil groove 66 is preferably formed at an angle similar to テ ー パ of the taper angle of the biting portion 16 in a direction inclined with respect to the center line. According to the present embodiment, even when the groove 26 is not formed in the entire axial direction of the male screw portion 14, the oil groove 66 for communicating the end of the groove 26 and the tip end surface of the biting portion 16 is formed. Therefore, there is an advantage that lubricating oil can be supplied to the rolled portion during female thread rolling.

FIG. 12 is an enlarged view of a main part of a raising tap 70 according to another embodiment of the present invention. In the figure, the projecting portion 20 ′ is formed over the entire biting portion 16 in the axial direction.
Is formed to the bottom of the second ground surface A ′ and a second groove 26 ′ continuous with the groove 26 is formed in that portion. The second ground surface A ′ and the second groove 26 ′ have the same cross-sectional shape as the groove 26, but at an angle similar to テ ー パ of the taper angle of the biting portion 16, It is formed in an inclined direction. Thereby, the biting portion 16
Similarly to the complete mountain portion 18, the second cutting edge 24 'is formed by removing a part of the protrusion 20 adjacent to the protrusion 20' in the axial direction to the valley bottom in the entire axial direction. Have been. According to the present embodiment, in the biting portion 16 where the rolling load is the largest, the excess thickness that reaches the root of the thread is removed by the second cutting edge 24 ′, so that a tapered cast hole or the like is used. When the female screw is formed in the pilot hole having the small diameter, the rotational torque is reduced, and the breakage of the raising tap 70 is suitably prevented.

While the embodiment of the present invention has been described with reference to the drawings, the present invention is applied to other embodiments.

For example, in the above-described embodiment, one of the protrusions 20 and 20 'formed along a predetermined spiral line.
Every other protrusion 20 'or every other protrusion 20'
However, when the predetermined number excluding 1 is one cycle, which is a divisor of the number of the projecting parts 20 per lead of the male screw part 14, the projecting part at a position corresponding to the one cycle is removed. 20 'may be removed to the bottom of the valley. Thereby, in the male screw portion 14, the protruding portions 20 'are continuously adjacent in the axial direction. For example, the protruding portions 20, 20 'per lead of the male thread portion 14
Is 4, every other protrusion (two protrusions per lead) 20 'or every third protrusion (one protrusion per lead) 20' is removed. .
Also, the protrusion 2 per lead of the male screw 14
When the number of 0 and 20 'is 6, every other protrusion (three protrusions per lead) 20', every other protrusion (two protrusions per lead) 20 ', Or 5
Every other protrusion (one protrusion per lead) 20 '
Is removed.

Further, in the embodiment of FIG.
Although the groove 4 and the groove 26 are formed over the entire area of the male screw portion 14 in the axial direction, a part of the male screw portion 14, preferably a part of the male screw portion 14 on the bite portion 16 side, and the bite portion 16 are formed. A certain effect can be obtained even if it is provided on the entire area in the axial direction or on a part of the biting part 16, preferably both or one part of the biting part 16 on the complete mountain part 18 side.

In the embodiment of FIG. 1 described above, the grinding surface A and the groove 26 are formed linearly in a direction parallel to the axis of the tapping tap 10, but they may be formed spirally. . Further, the linear or spiral oil groove is formed in the groove 2.
6 and may be formed over the entire area of the screw portion 14 in the axial direction. Further, the oil groove and the groove 26 may be connected in the middle of the axial direction.

Further, the raising tap 10 of the above-described embodiment,
50, 60, 62, 64 and 70 may be subjected to a surface hardening treatment by nitriding treatment and a surface coating treatment by TiN and TiCN coating on the surface,
High speed tool steel, cemented carbide, with a hardness of ~ 70 HRC,
It may be made of ultra-fine-grain cemented carbide. The surface of the cutting edge 24 may be subjected to a hard carbon film treatment.

In the above-described embodiment, the cutting edge 24
, Ie, the maximum diameter of the root is matched with the inner diameter of the internal thread, in the sense that the diameter of the cutting edge 24 is within the allowable range of the internal diameter of the internal thread to be rolled. is there.

In the above-described embodiment, the protrusion 20
Are formed at the same height, but a plurality of protrusions 20 ′ are provided between the grooves 26 by removing, for example, a plurality of protrusions 20 ′ in the circumferential direction, and are located behind the cutting edge 24 in the rotation direction. By sequentially increasing the height of the plurality of protrusions 20, the plastic deformation resistance applied to the protrusions 20 may be made uniform. If you do this,
Breakage of the protrusion 20 is suitably prevented, and the durability of the raised tap is increased.

The above is merely an embodiment of the present invention, and the present invention can be variously modified without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is a front view showing a raised tap according to an embodiment of the present invention.

FIG. 2 is an enlarged view illustrating a cross section of a male thread portion in the embodiment of FIG. 1; FIG. 2 is a diagram for explaining a manufacturing process of the forming tap of the embodiment of FIG. 1 and is a diagram for explaining a groove forming process.

1. FIG. 3 is a view for explaining a manufacturing process of the tapping tap of the embodiment of FIG. 1, and is a view showing a state in which a screw thread is formed by a screw polishing step.

FIG. 4 is a view for explaining a manufacturing process of the forming tap of the embodiment of FIG. 1, and is a view showing a state in which a ground surface A is formed by a protrusion removing step.

FIG. 5 is a view for explaining a process in which a female thread is rolled by the tapping tap of the embodiment of FIG. 1;

FIG. 6 is a cross-sectional view illustrating a conventional threaded portion of a raised tap with an internal diameter finishing blade.

FIG. 7 is a diagram corresponding to FIG. 2 for explaining another embodiment of the present invention.

FIG. 8 is a perspective view for explaining a material used for a raising tap of the embodiment in FIG. 7;

FIG. 9 is a view corresponding to FIG. 2 for explaining another embodiment of the present invention.

FIG. 10 is a diagram corresponding to FIG. 2 for explaining another embodiment of the present invention.

FIG. 11 is a view corresponding to FIG. 1, illustrating another embodiment of the present invention.

FIG. 12 is a diagram corresponding to FIG. 1 for explaining another embodiment of the present invention.

[Explanation of symbols]

 10, 50, 60, 62, 64, 70: Raised tap 14: Male thread portion 16: Biting portion 18: Complete ridge portion 20: Projection portion, 20 ': Projection portion 22: Relief portion 24: Cutting edge, 24' : Second cutting edge (cutting edge) 26: groove, 26 ′: second groove (groove)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-223119 (JP, A) JP-A 63-50615 (JP, U) JP-A 5-88836 (JP, U) (58) Survey Field (Int.Cl. ⁶ , DB name) B23G 5/06

Claims (6)

(57) [Claims] 1. A projection having a uniform height such that a projection projecting in the radial direction and a relief part having a small diameter subsequent to the projection are arranged alternately along the screw advancing direction and at a predetermined angular interval around the axis. An embossing having an external thread provided along a screw thread, and forming a female thread by plastically deforming the protrusion of the external thread by biting into a surface layer of a prepared hole provided in the workpiece. In the tap, the root diameter of a part of the protrusions located within one lead of the male screw part is set to be larger than the root diameter of the other protrusions, and the part of the protrusions is set to the bottom. And a groove for forming a cutting edge in a portion corresponding to the valley bottom of the removed portion. 2. The male thread portion has a bite portion having an outer diameter smaller toward the distal end side, and a complete crest portion having a constant outer diameter following the base end side of the bite portion. 2. The tap according to claim 1, wherein the diameter of the inner diameter finishing blade at the complete crest portion is made to match the inner diameter of the internal thread. 3. The raising tap with an inner diameter finishing blade according to claim 2, wherein the portion in which the protruding portion adjacent in the axial direction is removed to the valley bottom is formed over the entire axial direction of the male screw portion. 4. The raising tap with an inner diameter finishing blade according to claim 1, wherein the groove is formed over the entire area of the biting portion in the axial direction. 5. The groove is formed on the complete mountain side of the biting portion, and an oil groove following the groove is formed in the biting portion up to the tip of the biting portion. Item 7. A tapping tap with an internal finishing blade according to any one of Items 1 to 4. 6. The steel sheet according to claim 1, wherein at least the projecting portion and the cutting edge formed at the biting portion are made of a cemented carbide fixed to a part of a body of an alloy steel in a circumferential direction. Either of 5 above, a tap with a finishing blade.