JP7045906B2 - Method of forming a tapered female thread - Google Patents

Description

The present invention relates to a method for forming a tapered female threaded portion for forming a tapered female threaded portion on the inner peripheral surface of a prepared hole formed in the work.

Conventionally, in addition to punch punching such as punching by punch press, straight tap punching is performed to form a straight female threaded portion (parallel female threaded portion) on the inner peripheral surface of the pilot hole of a plate-shaped work (metal plate). (See Patent Document 1). The straight tap processing is performed by entering the pilot hole of the work while the straight tap in the upper mold for straight tap processing rotates.

In addition to Patent Document 1, there is a prior art related to the present invention shown in Patent Document 2.

Japanese Unexamined Patent Publication No. 2010-17763 Japanese Unexamined Patent Publication No. 5-50158

In recent years, there has been a growing demand for not only straight tap processing by punch pressing, but also taper tap processing for forming a tapered female thread portion in a prepared hole of a work. In order to meet that demand, development related to taper tap processing is being considered, such as changing the straight tap to a taper tap and manufacturing an upper die for taper tap processing.

On the other hand, in the case of taper tapping, the amount of work cut increases by the amount corresponding to the taper angle of the taper tap (tapered female thread), and the amount of chips generated and the amount of chips generated accordingly. The total processing amount of taps (taper taps) increases. Therefore, when the taper tap punch punching is performed, there is a problem that the time required for the chip removal process becomes long, the work efficiency is lowered, and it is not easy to extend the tool life of the tap (taper tap).

Therefore, an object of the present invention is to provide a method for forming a tapered female thread portion having a novel structure, which has one of the problems of solving the above-mentioned problems.

The method for forming the tapered female threaded portion according to the embodiment of the present invention is a method for forming the tapered female threaded portion on the inner peripheral surface of the prepared hole formed in the work, and the punch tip is said to be the work from above. By entering the prepared hole, the chamfered forming portion formed on the tip end side of the punch tip forms a chamfered portion on the front peripheral portion of the prepared hole of the work, and the tip of the chamfered forming portion is formed. The tapered tapered portion formed on the side forms a tapered portion having a tapered angle corresponding to the tapered female thread portion on the inner peripheral surface of the prepared hole of the work, and the die tip works from below. By entering the prepared hole, the second chamfered portion formed on the tip end side of the die tip forms a chamfered portion (second chamfered portion) on the peripheral edge portion on the back side of the prepared hole of the work. After that, the tapered tap having the same taper angle as the tapered female thread portion enters the prepared hole of the work while rotating to form the tapered female threaded portion in the tapered portion of the prepared hole of the work. ..

According to an embodiment of the present invention, the tapered female thread portion is formed on the inner peripheral surface of the prepared hole of the work by the tapered forming portion before the tapered female thread portion is formed on the inner peripheral surface (tapered portion) of the prepared hole of the work. Form a tapered portion. As a result, when taper tapping is performed by punch press, it is possible to suppress an increase in the cutting amount of the work and sufficiently reduce the amount of chips generated and the total amount of taper tapping.

According to the present invention, when the taper tap punch punching is performed, the time required for the chip removal process can be shortened, the work efficiency can be improved, and the tool life of the taper tap can be extended.

FIG. 1 is a cross-sectional view showing a die set for machining a tapered hole according to an embodiment of the present invention and its periphery. FIG. 1 shows how the pilot hole of the work is located between the punch tip and the die tip. FIG. 2 is a cross-sectional view showing a die set for machining a tapered hole according to an embodiment of the present invention and its periphery. FIG. 2 shows a state in which a chamfered portion or the like is formed on the front peripheral portion or the like on the front side of the prepared hole of the work. FIG. 3A is a cross-sectional view showing how a pilot hole is formed in the work. FIG. 3B is a cross-sectional view showing a state in which chamfered portions are formed on both side edges of the prepared hole of the work and tapered portions are formed on the inner peripheral surface of the prepared hole of the work. FIG. 3C is a cross-sectional view showing a state in which a tapered female thread portion is formed on the inner peripheral surface (tapered portion) of the pilot hole of the work. FIG. 4 is a cross-sectional view showing an upper die for taper hole drilling according to an embodiment of the present invention. FIG. 5A is a diagram showing a punch body and a punch tip in the upper die for taper hole drilling according to the embodiment of the present invention, and a part of FIG. 5A is a cross-sectional view. .. FIG. 5B is an enlarged view of the VB portion in FIG. 5A. FIG. 6 is a cross-sectional view showing a lower die for taper hole drilling according to the embodiment of the present invention. FIG. 7A is a plan view showing a die body and a die chip in the lower die for taper hole drilling according to the embodiment of the present invention. FIG. 7B is a cross-sectional view showing a die body and a die tip in the lower die for taper hole drilling according to the embodiment of the present invention, and a part of FIG. 7A is a cross-sectional view. FIG. 7 (c) is an enlarged view of the VIC portion in FIG. 7 (b). FIG. 8 is a cross-sectional view showing a die set for taper tap processing according to an embodiment of the present invention and its periphery. FIG. 8 shows how the pilot hole of the work is located directly below the taper tap. FIG. 9 is a cross-sectional view showing a die set for taper tap processing according to an embodiment of the present invention and its periphery. FIG. 9 shows how a tapered female threaded portion is formed on the inner peripheral surface (tapered portion) of the prepared hole of the work.

Hereinafter, the mold set for taper hole machining according to the embodiment of the present invention, the mold set for taper tap machining according to the embodiment of the present invention, the method for forming the tapered female thread portion according to the embodiment of the present invention, and the like will be described. This will be described in sequence with reference to the drawings.

In the specification of the present application and the scope of claims, "provided" means not only directly provided but also indirectly provided via another member. In the drawings, "U" refers to the upward direction and "D" refers to the downward direction.

As shown in FIGS. 1 and 2, the die set 1 for taper hole drilling according to the embodiment of the present invention includes an upper die (punch die) 3 for taper hole drilling and a lower die for taper hole drilling. It consists of a mold (die mold) 5. The upper die 3 for taper hole processing is detachably mounted in the mounting hole 9 of the upper turret 7 as the upper mounting base in the punch press. The lower die 5 for taper hole processing is detachably mounted in the mounting hole 15 of the lower die holder 13 provided in the lower turret 11 as the lower mounting base in the punch press. A part of the lower die 5 for taper hole processing is located in the through hole 17 formed in the lower turret 11.

As shown in FIGS. 1 to 3 (a), (b), and (c), the die set 1 for machining a tapered hole is provided on both sides (front side and front side) of a prepared hole H formed in a plate-shaped work (sheet metal) W. This is a device for forming chamfered portions C1 and C2 on the peripheral portion of the back side). Further, in the die set 1 for machining a tapered hole, one chamfered portion T of a tapered portion T having a taper angle θa corresponding to the tapered female threaded portion S formed on the inner peripheral surface of the prepared hole H of the work W in the next process. It is a device for continuously forming on C1. Here, the taper angle θa corresponding to the tapered female thread portion S means to include the same angle as the taper angle θb of the tapered female thread portion S and an angle slightly smaller than the taper angle θb of the tapered female thread portion S.

Subsequently, a specific configuration of the upper die 3 for chamfering according to the embodiment of the present invention will be described.

As shown in FIGS. 1, 2, 4, and 5 (a), the upper die 3 for taper hole machining includes a tubular punch guide 19, and the punch guide 19 is an upper turret 7. It can be mounted up and down (movable in the vertical direction) and detachably in the mounting hole 9. Further, a flange portion 21 is formed at the upper end portion of the punch guide 19, and the flange portion 21 is directed downward by a plurality of lifter springs (not shown) provided on the peripheral edge portion of the mounting hole 9 of the upper turret 7. Supported by. Further, an insertion hole 23 is formed through the central portion of the lower surface (lower portion) of the punch guide 19.

A punch body 25 is provided on the inside of the punch guide 19 so as to be able to move up and down, and a male screw portion 27 is formed on the outer peripheral surface of the punch body 25 on the upper end side. Further, a punch tip 29 is integrally provided in the central portion of the lower surface of the punch body 25, and the punch tip 29 can be inserted into the insertion hole 23. The punch tip 29 may be detachably attached to the lower surface of the punch body 25. The characteristic portion of the punch tip 29 will be described later.

An annular punch head 31 is screwed to the upper end portion (male screw portion 27) of the punch body 25. On the inner peripheral surface of the punch head 31, a female threaded portion 33 screwed with the male threaded portion 27 of the punch body 25 is formed. The punch head 31 is pressed (pressed) from above by the striker 35 in the punch press.

An annular retainer collar 37 is provided on the upper side of the punch guide 19 so as to surround the punch body 25. Further, between the punch head 31 and the retainer collar 37, a stripper spring 39 as an urging member for urging the punch body 25 upward with respect to the punch guide 19 is provided so as to surround the punch body 25. There is.

As shown in FIGS. 3 (a) and 3 (b), 4 and 5 (a) and 5 (b), a columnar straight portion 41 is formed on the base end side of the punch tip 29. The length dimension (vertical dimension) of the straight portion 41 is set to the same dimension as the thickness dimension of the lower part of the punch guide 19. Further, on the tip end side of the straight portion 41, a tapered chamfer forming portion 43 for forming the chamfered portion C1 is continuously formed on the peripheral portion on the front side (upper side) of the prepared hole H of the work W. There is. In other words, a tapered chamfer forming portion 43 is formed on the tip end side (lower end side) of the punch tip 29. The taper angle of the chamfer forming portion 43 (taper angle with respect to the axis of the upper die 3 for taper hole drilling) θc is 45 degrees, but may be appropriately changed within the range of 30 degrees to 60 degrees. ..

On the tip end side of the chamfer forming portion 43, a tapered tapered portion T for forming a tapered portion T having a tapered female thread portion S corresponding to the tapered female thread portion S on the inner peripheral surface of the prepared hole H of the work W is formed. The portions 45 are continuously formed. As a matter of course, the taper angle θd of the taper forming portion 45 (tapered angle with respect to the axis of the upper die 3 for taper hole processing) θd is the same as the taper angle θa of the tapered portion T. The length dimension of the taper forming portion 45 is set to be longer than the length dimension of the chamfer forming portion 43 and shorter than the length dimension of the straight portion 41.

When the punch body 25 abuts on the bottom surface 19b of the punch guide 19, the entire chamfered forming portion 43 of the punch tip 29 becomes the lower surface 19f of the punch guide 19 in the upper die 3 (mold set 1) for taper hole processing. It is configured to project downward with respect to.

Subsequently, the details of the configuration of the lower die 5 for taper hole drilling according to the embodiment of the present invention will be described.

As shown in FIGS. 1, 2, 6, and 7 (a) and 7 (b), the lower die 5 for taper hole processing includes a columnar (disk-shaped) die body 47, and the die body is provided. 47 is detachably mounted in the mounting hole 15 of the lower mold holder 13. Further, a plurality of stepped first guide holes 49 are formed through the peripheral portion (a portion around the central portion) of the die body 47. The plurality of first guide holes 49 are arranged at equal intervals along the circumferential direction. Further, a plurality of second guide holes 51 are formed through the peripheral portion of the die body 47. The plurality of second guide holes 51 are arranged at equal intervals along the circumferential direction. The first guide holes 49 and the second guide holes 51 are alternately arranged along the circumferential direction.

A die chip 53 is integrally provided at the center of the upper surface of the die body 47. The die chip 53 may be detachably attached to the die body 47. The characteristic portion of the die chip 53 will be described later.

On the upper side of the die body 47, a disk-shaped ejector 55 for separating the work W from the die chip 53 is provided so as to be able to move up and down. A second insertion hole 57 for inserting the die chip 53 is formed through the central portion of the ejector 55. Further, each first guide hole 49 of the die body 47 is provided with a connecting bolt 59 that can be raised and lowered, and the upper end portion of each connecting bolt 59 is fixed to the ejector 55 by screwing. A slide pin 61 is provided in each of the second guide holes 51 of the die body 47 so as to be able to move up and down, and the upper end portion of each slide pin 61 is fixed to the ejector 55 by screwing. In other words, on the upper side of the die body 47, an ejector 55 is provided so as to be able to move up and down and cannot be detached via a plurality of connecting bolts 59 and a plurality of slide pins 61.

A mounting bolt 63 is screwed into the central portion of the lower surface of the die body 47, and the mounting bolt 63 is located in the through hole 17 of the lower turret 11. An annular spring seat 65 is provided at the lower end of the mounting bolt 63. A support collar 67 that supports a plurality of slide pins 61 from below is provided on the upper end side of the mounting bolt 63 so as to be able to move up and down. A coil spring 69 as a second urging member is provided between the support collar 67 and the spring seat 65. The coil spring 69 urges the ejector 55 upward with respect to the die body 47 via the support collar 67 and the plurality of slide pins 61.

As shown in FIGS. 3 (a), 3 (b), 6 and 7 (a), (b) and (c), a columnar straight portion 71 is formed on the base end side of the die chip 53. On the tip end side of the straight portion 71, a tapered second chamfer forming portion 73 for forming the chamfered portion C2 is continuously formed on the peripheral edge portion on the back side (lower side) of the prepared hole H of the work W. ing. In other words, a tapered second chamfer forming portion 73 is formed on the tip end side (upper end side) of the die chip 53. A short columnar straight portion 75 is formed on the tip end side of the second chamfer forming portion 73. The length dimension (vertical dimension) of the straight portion 75 is set to be smaller than the length dimension of the second chamfer forming portion 73. The taper angle θe (taper angle with respect to the axis of the lower die 5 for taper hole drilling) of the second chamfer forming portion 73 is 45 degrees, but it is appropriately changed within the range of 30 degrees to 60 degrees. You may. The straight portion 75 may be omitted from the configuration of the die chip 53.

Then, in the lower die 5 (die set 1) for taper hole processing, when the ejector 55 abuts on the upper surface of the die body 47, the entire second chamfer forming portion 73 of the die tip 53 is relative to the upper surface of the ejector 55. It is configured to project upward.

As shown in FIGS. 3 (a), 3 (b), 8 and 9, the mold set 77 for taper tap processing according to the embodiment of the present invention includes an upper mold 79 for taper tap processing and a taper tap processing mold set 77. It consists of a lower mold 81. Further, the die set 77 for taper tapping according to the embodiment of the present invention is a device for forming a tapered female thread portion S on the inner peripheral surface (tapered portion T) of the prepared hole H of the work W.

The upper mold 79 for taper tap processing is detachably mounted in the other mounting holes 9A of the upper turret 7. The lower die 81 for taper tap processing is detachably mounted in the mounting hole 15A of another lower die holder 13A provided in the lower turret 11. Further, the upper mold 79 for taper tap processing has the same configuration as the upper mold for straight tap processing shown in Japanese Patent Application Laid-Open No. 2010-17763 (Patent Document 1), except for a part. Then, the configuration of the upper die 79 for taper tap processing and the like will be briefly described as follows.

As shown in FIGS. 8 and 9, the upper die 79 for taper tap processing includes a cylindrical tap guide 83 detachably provided in another mounting hole 9A of the upper turret 7. The tap guide 83 is supported from below by a plurality of lifter springs (not shown) provided on the peripheral edge of the other mounting holes 9A of the upper turret 7. Further, inside the tap guide 83, the operating member 85 is provided so as to be rotatable and movable. The actuating member 85 has a pipe-shaped small diameter portion 85a and a cylindrical large diameter portion 85b at the top and bottom. A master male threaded portion 87 having the same pitch as the tapered female threaded portion S is formed on the outer peripheral surface of the small diameter portion 85a of the operating member 85 on the base end side (upper end side).

Inside the large diameter portion 85b of the actuating member 85, a tap holder 91 for holding the tapered tap 89 is provided so as to be able to move up and down and not rotate. The tap holder 91 is urged downward by a spring 93 provided inside the actuating member 85. Further, a screw cap 95 is provided in the middle portion inside the tap guide 83 so as to be movable and non-rotatable. The screw cap 95 is supported from below by a spring 97 provided on the outer peripheral side of the large diameter portion 85b of the operating member 85. On the inner peripheral surface of the screw cap 95, a master female screw portion 99 to be screwed into the master male screw portion 87 is formed.

A drive sleeve 101 is rotatably provided on the upper end side of the tap guide 83. The drive sleeve 101 transmits rotational force from the drive gear 105 in the gear case 103 provided on the upper turret 7. The drive gear 105 is rotated by driving a rotary motor 107 provided on the upper turret 7. Further, a connecting member 109 is provided on the tip end side of the small diameter portion 85a of the operating member 85 so as to be able to move up and down and not rotate. A circular head member 111 is rotatably provided on the upper surface side of the connecting member 109. The connecting member 109 is configured to be non-rotatably connected to the drive sleeve 101 when the head member 111 is pressed from above by the striker 35.

An entry hole 113 for allowing the taper tap 89 to enter is formed in the central portion of the upper surface (upper portion) of the lower die 81 for taper tap processing. The entry hole 113 communicates with the through hole 17A formed in the lower turret 11.

Subsequently, a method for forming the tapered female thread portion according to the embodiment of the present invention will be described including the operation of the embodiment of the present invention.

As shown in FIGS. 3A, 3B, and 3C, in the method for forming the tapered female thread portion according to the embodiment of the present invention, the tapered female threaded portion S is formed on the inner peripheral surface of the prepared hole H formed in the work W. It is a method for forming, and includes a tapered hole processing step and a taper tap processing step. Further, the pilot hole H of the work W is formed by two punching processes in the previous process. In the first punching process, a hole H'is formed in the work W by a shaving allowance (cutting allowance) Hf smaller than the prepared hole H. In the second punching process, the shaving allowance Hf is scraped off to form a pilot hole H in the work W. A pilot hole H may be formed in the work W by one punching process. A pilot hole H may be formed in the work W by laser machining with a laser machining device (not shown).

Tapered hole machining step As shown in FIGS. 1, 2, and 3 (a) and 3 (b), the work W is formed by forming a pilot hole H in the work W and then rotating the upper turret 7 and the lower turret 11. Is moved in the horizontal direction relative to the mold set 1 for taper hole drilling. As a result, the work W can be positioned relative to the die set 1 for machining the tapered hole so that the prepared hole H of the work W is located between the punch tip 29 and the die tip 53.

After that, the punch head 31 is pressed from above by the striker 35 to lower the punch body 25. Then, the punch guide 19 descends integrally with the punch body 25 while resisting the urging force of the plurality of lifter springs, and the peripheral portion of the pilot hole H of the work W is provided by the lower surface 19f of the punch guide 19 and the upper surface 55f of the ejector 55. Hold.

Then, the ejector 55 descends while resisting the urging force of the coil spring 69 due to the descending operation of the punch body 25. Then, the die chip 53 protrudes upward from the second insertion hole 57 with respect to the upper surface of the ejector 55, and enters the prepared hole H of the work W from below. Further, when the ejector 55 abuts on the upper surface 47f of the die body 47, the entire second chamfer forming portion 73 of the die chip 53 projects upward from the second insertion hole 57 with respect to the upper surface of the ejector 55. As a result, the chamfered portion C2 is formed on the peripheral edge portion on the back side of the prepared hole H of the work W by the second chamfered forming portion 73 of the die chip 53.

Further, the lowering motion of the punch body 25 causes the punch body 25 to descend with respect to the punch guide 19 while resisting the urging force of the stripper spring 39. Then, the punch tip 29 protrudes downward with respect to the lower surface 19f of the punch guide 19, and enters the pilot hole H of the work W from above. Further, when the punch body 25 abuts on the bottom surface 19b of the punch guide 19, the entire chamfer forming portion 43 of the punch tip 29 projects downward with respect to the lower surface 19f of the punch guide 19. As a result, the chamfered portion 43 of the punch tip 29 forms the chamfered portion C1 on the peripheral edge portion on the back side of the prepared hole H of the work W, and the tapered forming portion 45 of the punch tip 29 forms the inner peripheral surface of the prepared hole H. A tapered portion T is formed on the surface. That is, the prepared hole H is finished into a tapered hole with chamfered portions C1 and C2.

After forming the chamfered portion C1 and the tapered portion T, the die set 1 for taper hole drilling is returned to the original state by performing an operation opposite to the above-mentioned operation. This completes the taper hole drilling step.

Taper tapping step As shown in FIGS. 3 (b) (c), 8 and 9, the work W is used for taper tapping by rotating the upper turret 7 and the lower turret 11 after the taper hole machining step is completed. Is moved horizontally with respect to the mold set 77 of. As a result, the work W can be positioned relative to the die set 77 for taper tap processing so that the pilot hole (taper hole) H of the work W is located directly below the taper tap 89.

After that, the head member 111 is pressed from above by the striker 35. Then, the connecting member 109 descends to connect to the drive sleeve 101 so as not to rotate, and the operating member 85 and the screw cap 95 descend integrally with the drive sleeve 101. Then, by rotating the drive gear 105 by driving the rotary motor 107, the connecting member 109 is rotated, and the operating member 85 is lowered while rotating by the screwing action of the master male screw portion 87 and the master female screw portion 99. Then, the taper tap 89 descends while rotating, and enters the prepared hole H of the work W from above. As a result, with the lower end of the tap guide 83 in non-contact with the surface of the work W, the tapered portion T (inner peripheral surface of the prepared hole H) of the prepared hole H of the work W is tapered tapped. The tapered female thread portion S can be formed.

After forming the tapered female thread portion S, the die set 77 for taper tap processing is returned to the original state by performing an operation opposite to the above-mentioned operation. As a result, the taper tap processing step is completed.

According to the embodiment of the present invention, as described above, when the punch tip 29 enters the prepared hole H of the work W from above, the tapered forming portion 45 causes a tapered portion on the inner peripheral surface of the prepared hole H of the work W. Form T. As a result, when taper tap punching is performed by punch press, it is possible to suppress an increase in the cutting amount of the work W and sufficiently reduce the amount of chips generated and the total amount of taper tap 89 processed. In addition, it is possible to reduce the processing torque when performing taper tap processing.

As described above, when the punch tip enters the prepared hole H of the work W from above, the chamfer forming portion 43 forms the chamfered portion C1 on the front peripheral portion of the prepared hole H of the work W. Further, when the die chip 53 enters the prepared hole H of the work W from below, the second chamfer forming portion 73 forms the chamfered portion C2 on the peripheral edge portion on the back side of the prepared hole H of the work W. As a result, when the taper tap processing is performed, the biting property of the taper tap 89 to the work W can be enhanced, and the swelling of the material (meat) of the work W on the front surface and the back surface of the work W can be suppressed.

As described above, when the entire chamfer forming portion 43 of the punch tip 29 projects downward with respect to the lower surface 19f of the punch guide 19, the punch body 25 abuts on the bottom surface 19b of the punch guide 19. Further, when the ejector 55 abuts on the upper surface of the die body 47, the entire second chamfer forming portion 73 of the die chip 53 projects upward relative to the upper surface of the ejector 55. As a result, the tapered portion T and the chamfered portions C1 and C2 are firmly sandwiched between the lower surface 19f of the punch guide 19 and the upper surface 55f of the ejector 55 in the prepared hole H of the work W. Can be formed. As a result, the shape accuracy (machining accuracy) of the tapered portion T and the chamfered portions C1 and C2 can be sufficiently ensured.

In particular, as described above, a short columnar straight portion 75 is continuously formed on the tip end side of the second chamfer forming portion 73 of the die chip 53. Therefore, when the tapered portion T and the chamfered portions C1 and C2 are formed, the material of the work W is prevented from flowing (swelling) inward in the radial direction of the prepared hole H between the tapered portion T and the chamfered portion C2. , The shape accuracy of the tapered portion T and the chamfered portion C2 can be more sufficiently ensured.

Therefore, according to the embodiment of the present invention, as described above, when the taper tap punching is performed by the punch press, the amount of chips generated and the total amount of the taper tap 89 can be sufficiently reduced. Therefore, according to the embodiment of the present invention, when the taper tap punch punching is performed, the time required for the chip removal process is shortened, the work efficiency is improved, and the tool life of the taper tap 89 is extended. can.

According to the embodiment of the present invention, as described above, when the taper tap processing is performed, the biting property of the taper tap 89 to the work W is enhanced, and the material (meat) of the work W is applied to the front surface and the back surface of the work W. It is possible to suppress the excitement of. Further, the shape accuracy of the tapered portion T and the chamfered portions C1 and C2 can be sufficiently ensured. Therefore, the tapered female thread portion S can be finished with high accuracy.

According to the embodiment of the present invention, since the machining torque at the time of taper tap machining can be reduced, it is possible to suppress an increase in the motor capacity of the rotary motor 107 and reduce the cost.

The present invention is not limited to the above description of the embodiment, and can be implemented in various other embodiments by making appropriate changes. The scope of rights included in the present invention is not limited to the above-described embodiment.

1 Mold set for taper hole drilling 3 Upper mold for taper hole drilling 5 Lower mold for taper hole drilling 7 Upper turret 9 Mounting hole 9A Other mounting holes 11 Lower turret 13 Lower mold holder 13A Other bottom Mold holder 15 Mounting hole 15A Mounting hole 17 Through hole 17A Through hole 19 Punch guide 19b Bottom surface 19f Bottom surface 21 Flange part 23 Insertion hole 25 Punch body 27 Male thread part 29 Punch tip 31 Punch head 33 Female thread part 35 Striker 37 Retainer collar 39 Stripper Spring (urging member)
41 Straight part 43 Chamfer forming part 45 Chamfer forming part 47 Die body 49 1st guide hole 51 2nd guide hole 53 Die tip 55 Ejector 57 2nd insertion hole 59 Connecting bolt 61 Slide pin 63 Mounting bolt 65 Spring seat 67 Support collar 69 Coil Spring 71 Straight part 73 Second chamfer forming part 75 Straight part 77 Mold set for taper tap processing 79 Upper mold for taper tap processing 81 Lower mold for taper tap processing 83 Tap guide 85 Actuating member 85a Small diameter part 85b Large diameter 87 Master male thread 89 Tapered tap 91 Tap holder 93 Spring 95 Thread cap 97 Spring 99 Master female thread 101 Drive sleeve 103 Gear case 105 Drive gear 107 Rotating motor 109 Connection member 111 Head member 113 Entry hole W Work H Pilot hole Hf Shaving allowance H 'A hole smaller than the pilot hole by the amount of shaving allowance C1 Chamfered part C2 Chamfered part T Tapered part S Tapered female threaded part

Claims (1)

It is a method for forming a tapered female thread on the inner peripheral surface of the prepared hole formed in the work.
When the punch tip enters the prepared hole of the work from above, the chamfered portion formed on the tip end side of the punch tip forms a chamfered portion on the front peripheral edge of the prepared hole of the work. In addition, by the tapered tapered forming portion formed on the tip end side of the chamfer forming portion, a tapered portion having a tapered angle corresponding to the tapered female thread portion is formed on the inner peripheral surface of the prepared hole of the work. At the same time
When the die chip enters the pilot hole of the work from below, the second chamfer forming portion formed on the tip end side of the die chip forms a chamfered portion on the peripheral edge portion on the back side of the pilot hole of the work.
After that, the taper tap having the same taper angle as the tapered female thread portion enters the prepared hole of the work while rotating, so that the tapered female thread portion is formed in the tapered portion of the prepared hole of the work. How to form the part.

Images