JP5329504B2 - Raising tap - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thread forming tap capable of preventing welding or adhesion in a full thread part by reducing working torque while suppressing a pitch error by maintaining guide properties of the full thread part. <P>SOLUTION: Working for threaded chamfer is applied to the top of a thread of a second full thread part 32b, and the outer diameter of the thread of the second full thread part 32b is set so as to be less than (D-(3/4)H), i.e., to be smaller than a prepared hole having a diameter the same as that of an effective diameter (dimension D2) of a female thread. Accordingly, in a plastic working process of the female thread, an abutment area between the thread of the second full thread part 32b and the female thread formed on the working object formed by the plastic information by a leading part 31 is reduced. Because the friction between the thread of the second full thread part 32b and the female thread formed on the working object by the plastic deformation is thereby reduced, the working torque in the plastic working process of the female thread is reduced to prevent welding or adhesion in the second full thread part 32b. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a raised tap, and more particularly, to a raised tap that can suppress the occurrence of welding or adhesion in a complete mountain portion by reducing a processing torque while maintaining a guide property of the complete mountain portion and suppressing a pitch error. Is.

  Conventionally, taps are used to form female threads. This tap mainly includes a cutting tap for forming a female screw by cutting the surface layer portion of the pilot hole and a raised tap for forming a female screw by plastic deformation of the surface layer portion of the pilot hole.

  Since the cutting tap generates chips when tapping, it requires a chip removal operation and has a drawback that the finished surface becomes rough. On the other hand, the raised tap has features that no chips are generated during tapping, and the finished surface of the female thread is smooth and its strength is high, and has been used in various fields. .

  For example, in Japanese Patent Application Laid-Open No. 2006-068822, a shank portion formed in a columnar shape, a biting portion disposed on the tip side of the shank portion and formed in a tapered shape, and the biting portion are continuously provided. There is disclosed a raised tap configured to include a male screw portion having a complete thread portion and an oil groove recessed in an outer peripheral surface of the male screw portion.

Japanese Patent Laying-Open No. 2006-068822 (for example, FIG. 1)

  However, in the above-described conventional raised tap, in the female screw plastic working step, the female thread size of the workpiece plastically deformed by the biting portion becomes the original shape without screws due to the internal residual stress of the work piece structure. In order to return, the female thread size of the workpiece is slightly smaller than the tap size. During the formation of the female thread, it is formed as a complete thread portion, so that there is a problem that the processing torque increases due to friction with the screw, and the workpiece is easily welded or adhered to the complete thread portion. On the other hand, if the number of threads in the complete ridge is reduced, welding and adhesion to the complete ridge can be suppressed by reducing the processing torque, but the guide of the complete ridge does not function sufficiently, and the pitch There was a problem that errors were likely to occur.

  The present invention has been made in order to solve the above-described problems, and while maintaining the guide property of the complete peak portion to suppress the pitch error, the processing torque is reduced and welding or adhesion to the complete peak portion is achieved. An object of the present invention is to provide a raised tap that can suppress the occurrence of the above.

Means for Solving the Problems and Effects of the Invention

  According to the rising tap of the first aspect, since the top of the thread of the second complete thread is machined and the outer diameter of the second complete thread is set smaller than the inner diameter of the pilot hole. In the plastic processing step of the screw, the contact area between the female screw formed on the workpiece and the second complete thread portion by the plastic deformation by the biting portion can be reduced. Therefore, the friction between the screw and the screw thread of the second complete thread portion can be reduced because it is formed on the work piece by plastic deformation, so that the processing torque in the plastic working process of the female thread is reduced and welded to the second complete thread portion. And the effect of suppressing the occurrence of adhesion. As a result, the tool life of the raised tap can be extended.

  Further, by chamfering the top of the screw thread of the second complete thread portion, in the plastic working process of the internal thread, between the screw thread of the second complete thread portion and the female screw formed on the workpiece. Therefore, the tapping oil supplied to the plastic working surface from the shank side through the oil groove can be spread over the gap. As a result, the friction generated by the tapping oil can reduce the friction generated at the contact portion between the thread of the male thread and the female thread formed on the work piece, thereby reducing the processing torque in the plastic working process of the female thread. In addition, there is an effect that it is possible to suppress the occurrence of welding or adhesion on the screw portion.

  Moreover, by ensuring the guide property as a complete thread by making the number of threads of the first complete thread part 2 or more, the number of threads of the first complete thread part is made 4 or less. The contact area between the thread of the second complete thread and the female thread formed on the workpiece can be reduced. Therefore, while controlling the pitch error of the female screw and forming a high-precision female screw, the friction with the female screw is suppressed, and the processing torque in the plastic processing process of the female screw is reduced, so that welding and adhesion are completely performed on the complete thread. There is an effect that it is possible to suppress the occurrence of wearing.

  Furthermore, the number of threads of the first complete thread is set to 2 or more and 4 or less, the number of threads of the complete thread is set to 8 or more, and the outer diameter of the second complete thread is the female thread. Since it is set larger than the inner diameter, the thread of the second complete thread can be guided to the female thread formed on the workpiece. Therefore, since the guide property of the second complete thread portion can be maintained, even when a long female screw is formed or a through hole is formed, the pitch error of the female screw is suppressed in the plastic working process of the female screw. There is an effect that a highly accurate internal thread can be formed.

  According to the build-up tap according to claim 2, the top of the thread of the guide part is threaded and the outer diameter of the thread of the second complete thread is set to less than (D- (3/4) H). Thus, in the plastic thread plastic working step, the contact area between the female thread formed on the workpiece and the second complete thread portion by the plastic deformation by the biting portion can be reduced. Therefore, the friction between the screw and the screw thread of the second complete thread portion can be reduced because it is formed on the work piece by plastic deformation, so that the processing torque in the plastic working process of the female thread is reduced and welded to the second complete thread portion. And the effect of suppressing the occurrence of adhesion. As a result, the tool life of the raised tap can be extended.

  Further, by chamfering the top of the screw thread of the second complete thread portion, in the plastic working process of the internal thread, between the screw thread of the second complete thread portion and the female screw formed on the workpiece. Therefore, the tapping oil supplied to the plastic working surface from the shank side through the oil groove can be spread over the gap. As a result, the friction generated by the tapping oil can reduce the friction generated at the contact portion between the thread of the male thread and the female thread formed on the work piece, thereby reducing the processing torque in the plastic working process of the female thread. In addition, there is an effect that it is possible to suppress the occurrence of welding or adhesion on the screw portion.

  Moreover, by ensuring the guide property as a complete thread by making the number of threads of the first complete thread part 2 or more, the number of threads of the first complete thread part is made 4 or less. The contact area between the thread of the second complete thread and the female thread formed on the workpiece can be reduced. Therefore, while controlling the pitch error of the female screw and forming a high-precision female screw, the friction with the female screw is suppressed, and the processing torque in the plastic processing process of the female screw is reduced, so that welding and adhesion are completely performed on the complete thread. There is an effect that it is possible to suppress the occurrence of wearing.

  Furthermore, the number of threads in the first complete thread is set to 2 or more and 4 or less, and the number of threads in the complete thread is set to 8 or more. Since the outer diameter of the thread of the second complete thread is set to (D- (3/4) H-0.2H) or more, the thread after the thread is removed. The screw thread of the second complete thread part can be guided to the female thread formed on the workpiece. Therefore, since the guide property of the second complete thread portion can be maintained, even when a long female screw is formed or a through hole is formed, the pitch error of the female screw in the plastic working process of the female screw is reduced. It has the effect that it can suppress and can form a highly accurate internal thread.

  According to the rising tap according to claim 3, in addition to the effect of the rising tap according to claim 1 or 2, the second complete thread portion is threaded in a concentric arc shape when all the screw threads are viewed in the axial direction of the shank. Since it is machined, the top of the thread where the second complete thread is formed is ground while rotating the threaded material around the axis of the shank when the second complete thread is removed. By chamfering with a grindstone, the top of the thread of the second complete thread portion can be cut off. Therefore, there is an effect that it is possible to efficiently perform the wiping processing of the second complete hill portion.

It is a front view of the raising tap in one embodiment of the present invention. (A) is sectional drawing of the rising tap in the IIa-IIa line of FIG. 1, (b) is sectional drawing of the rising tap in the IIb-IIb line of FIG. (A) is sectional drawing of the rising tap cut | disconnected by the plane containing the axial center and the largest outer-diameter part of an external thread part, (b) is expanded and shown the IIIb part of Fig.3 (a). It is the elements on larger scale of a screw part. It is a graph which shows the test result of a processing torque measurement test.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. First, with reference to FIG. 1, a schematic configuration of a build-up tap 100 according to an embodiment of the present invention will be described. FIG. 1 is a front view of a raised tap 100 according to an embodiment of the present invention, in which a male screw portion 30 is schematically illustrated.

  As shown in FIG. 1, the rising tap 100 includes a shank 20 formed in a columnar shape and a male screw portion 30 disposed on the tip side (left side in FIG. 1) of the shank 20, and holds the shank 20. It is a tool used for the purpose of forming a female thread in a pilot hole of a workpiece by a rotational force of a processing machine transmitted through a holder (not shown) and a feed suitable for a screw lead. Note that the internal thread machining by the rising tap 100 is not limited to machining by a machining center or the like, and may be performed manually.

  The shank 20 is made of a high-speed tool steel and is formed in a columnar shape having an axis O, and a shank square portion 20a having a substantially square cross section is provided on the rear end side (right side in FIG. 1). . The material of the shank 20 is not limited to high-speed tool steel, and may be composed of a cemented carbide.

  The male screw part 30 is a part for forming a female screw by screwing in a pilot hole provided in the workpiece (plastic processing). An oil groove 40 is formed on the outer peripheral surface of the male screw part 30. It is recessed substantially parallel to the axis O. The male screw portion 30 includes a biting portion 31 that plastically deforms the female screw, and a complete mountain portion 32 that is connected to the biting portion 31.

  The biting portion 31 is a portion for plastic working and forming a female screw by biting into the prepared hole surface layer portion of the workpiece and plastically deforming the workpiece. The complete thread portion 32 is a part that improves the finish and guide or self-guiding property of the surface of the female thread in the plastic working process of the female thread on the workpiece. Part 32a, and a second complete mountain part 32b connected to the first complete mountain part 32a.

  In the first complete crest portion 32a, a thread having a substantially uniform height from the bottom of the valley is formed along a spiral line having a predetermined lead angle. The second complete thread portion 32b is formed with a thread having the same shape as that of the first complete thread portion 32a, and then the tops of all the thread threads are subjected to a thread removal process. A thread having a substantially uniform height is formed along a spiral line having a predetermined lead angle. That is, the outer diameter of the second complete peak portion 32b is set to be smaller than that of the first complete peak portion 32a by the amount of the mountain-wiping process.

  The oil groove 40 is a groove for enhancing the lubrication effect in the plastic thread machining process, and supplies tapping oil to the plastic machining surface. Since the oil groove 40 is formed in a substantially linear shape while extending from the front end side to the rear end side of the male screw portion 30, the oil groove 40 is processed after the thread grinding step of the male screw portion 30. It can be done easily.

  In the present embodiment, the oil groove 40 is provided in parallel to the axis O, but is not necessarily limited thereto, and may be provided in a spiral shape. Moreover, the oil groove 40 does not need to extend from the front end side to the rear end side of the male screw portion 30, and may be provided only in a part of the male screw portion 30. For example, you may provide only in the front end side of the external thread part 30. FIG.

  Next, with reference to FIG. 2, the structure of the external thread part 30 is demonstrated. 2A is a cross-sectional view of the raised tap 100 taken along line IIa-IIa in FIG. 1, and FIG. 2B is a cross-sectional view of the raised tap 100 taken along line IIb-IIb in FIG. 2 (a) and 2 (b), a cross-sectional view of the male thread portion 30 cut along the bottom of the thread is shown in order to simplify the drawing and facilitate understanding. The hole Ho is illustrated by a two-dot chain line.

  As shown in FIGS. 2A and 2B, the external thread portion 30 has a substantially octagonal shape having eight sides whose cross section perpendicular to the axis O of the shank 20 (see FIG. 1) is curved outward. Is formed. In addition, on the outer peripheral surface of the male screw part 30, oil grooves 40 are recessedly provided on each of eight relief parts 60 described later, each having a substantially semicircular shape when viewed in cross section. A margin portion 50 protruding in the radial direction is disposed. The cross-sectional shape of the oil groove 40 is not particularly limited, and may be recessed in a substantially V shape in cross-sectional view.

  The margin part 50 is a part for plastically deforming the work piece by plastic biting into the work piece surface layer part of the work piece and screwing it, and is positioned substantially parallel to the axis O. In addition, a clearance portion 60 having a small diameter is formed between the margins 50. In other words, in the thread of the male screw portion 30, a margin portion 50 and a small-diameter relief portion 60 protruding in the radial direction are alternately arranged along the screw advance direction, that is, along the spiral line having a predetermined lead angle. And it is formed continuously around the axis O. The margin portion 50 includes a first margin portion 51 disposed in the first complete peak portion 32a and a second margin portion 52 disposed in the second complete peak portion 32b.

  In addition, the second complete thread portion 32b is formed by threading the tops of all screw threads in a concentric arc shape when viewed in the direction of the axis O. Therefore, when forming the second complete thread part 32b, after grinding the thread having the same shape as the first complete thread part 32a, the material on which the thread is formed is rotated around the axis O, The top of the thread of the second complete thread part 32b can be removed by cylindrical grinding with a grinding wheel. Therefore, it is possible to efficiently perform the pile removal processing of the second complete peak portion 32b.

  It should be noted that the outer diameter of the second complete crest portion 32b after the chamfering process is smaller than the inner diameter of the pilot hole Ho that is formed in the workpiece in advance when the female thread machining by the rising tap 100 is performed, and the workpiece It is set larger than the inner diameter of the formed female screw. In the present embodiment, the inner diameter of the pilot hole Ho is set to be approximately the same as the effective diameter of the female screw formed on the workpiece (that is, the effective diameter of the complete thread portion 32).

  Next, with reference to FIG. 3, the detailed structure of the biting part 31 and the complete mountain part 32 is demonstrated. 3A is a cross-sectional view of the raised tap 100 cut along a plane including the axis O and the maximum outer diameter portion of the external thread portion 30, and FIG. 3B is a cross-sectional view taken along the IIIb portion of FIG. It is the elements on larger scale of the external thread part 30 expanded and shown.

  As shown in FIGS. 3 (a) and 3 (b), the biting portion 31 is formed in a tapered shape having a smaller diameter toward the tip side (left side in FIG. 3). In the present embodiment, the number of threads of the bite portion 31 is two, but this is not necessarily limited to this, and the number of threads is arbitrary.

  The first complete thread part 32a is formed in the prepared hole surface layer part of the workpiece in substantially the same shape as the thread of the female thread to be plastically processed. Thereby, in the plastic working process of a female screw, finishing and guide of a female screw surface or self-guideability can be improved. In addition, the outer diameter of the 1st complete mountain part 32a is set to the dimension D, and the effective diameter of the internal thread formed in a workpiece is set to the dimension D2. In addition, as described above, in the present embodiment, the dimension D2 corresponds to the effective diameter of the complete mountain portion 32.

  When the chamfering process is performed on the top of the thread of the second complete crest portion 32b, the dimension D1 that is the outer diameter of the second complete crest portion 32b after the chamfering process is formed on the workpiece. It is set smaller than the dimension D2, which is the effective diameter of the screw, by a dimension h on one side (D1 = D2-2h). This dimension h is preferably set in a range larger than 0 and 0.1 H or less, where the height H of the complete peak portion 32 is defined as dimension H. That is, the height of the screw thread of the second complete thread portion 32b after the pile payout is ((5/8) H− (3/8) H−0.1H) = (0.15H) or more and ((5 / 8) H− (3/8) H−0) = less than (0.25H), whereby the outer diameter of the second complete peak portion 32b is (D− (3/8) H × 2-0. 1H × 2) = (D− (3/4) H−0.2H) or more and less than (D− (3/8) H × 2−0) = (D− (3/4) H) It is preferable.

  Note that (D- (3/4) H) is the same as the dimension D2 which is the effective diameter of the internal thread, and is the internal diameter of the internal thread, the internal diameter of the internal thread, and the external diameter of the external thread. The respective reference dimensions of the diameter, the effective diameter of the male screw, and the diameter of the valley of the male screw are determined based on the standard mountain shape of JISB0101. Further, the rising tap 100 according to the present embodiment is set to M16 × 1.5, the dimension D is 16.000 mm, the dimension D2 is 15.26 mm, and the height H of the complete peak portion 32 is 1.299 mm. ing. In this case, it is preferable that the dimension D1 is set to be 14.766 mm or more and less than 15.5.026, and in the present embodiment, the dimension D1 is set to 14.976 mm.

  The outer diameter of the thread of the second complete thread portion 32b is less than (D- (3/4) H), that is, the pilot hole Ho (see FIG. 2 (b)) having substantially the same size as the effective diameter (dimension D2) of the female thread. Therefore, in the female screw plastic working step, the contact area between the female screw formed on the workpiece by the plastic deformation by the biting portion 31 and the screw thread of the second complete thread portion 32b. Can be reduced. Accordingly, since the friction between the screw and the screw thread of the second complete thread portion 32b can be reduced because it is formed on the workpiece by plastic deformation, the second complete thread portion 32b can be reduced by reducing the processing torque in the plastic thread processing step. It is possible to suppress the occurrence of welding and adhesion on the surface. As a result, the tool life of the raised tap 100 can be extended.

  Further, the outer diameter of the screw thread of the second complete thread portion 32b is less than (D- (3/4) H), that is, the pilot hole Ho (see FIG. By setting it smaller than (b), a gap is formed between the thread of the second complete thread 32b and the female thread formed on the workpiece in the plastic thread machining process. The tapping oil supplied to the plastic working surface from the shank 20 (see FIG. 1) side through the oil groove 40 (see FIG. 1) can be spread over the gap. As a result, the friction generated in the contact portion between the thread of the external thread 30 and the internal thread formed on the workpiece can be reduced by the lubricating effect of the tapping oil, so that the processing torque in the plastic processing process of the internal thread can be reduced. In addition, it is possible to suppress the occurrence of welding or adhesion on the screw portion 30.

  Moreover, since the outer diameter of the screw thread of the second complete thread part 32b is set to (D- (3/4) H-0.2H) or more, the screw of the second complete thread part 32b after being removed. The crest can be guided by a female screw formed on the workpiece. That is, the difference between the reference dimension of the effective diameter of the internal thread and the reference dimension of the internal diameter of the internal thread is (1/4) H, and the dimension D2 that is the effective diameter of the internal thread formed on the workpiece and the second complete The dimension h which is the difference from the dimension D1 which is the outer diameter of the peak portion 32b is set to be larger than 0 and 0.1H or less. Accordingly, since the outer diameter of the second complete thread portion 32b after the thread removal is larger than the reference dimension of the inner diameter of the female screw, the thread of the second complete thread portion 32b is used as a workpiece in the plastic thread machining process. Can be meshed with the thread formed on. Therefore, since the thread of the second complete thread portion 32b is formed on the workpiece and can be guided by the screw, the pitch error of the female thread can be suppressed and a highly accurate female thread can be formed.

  Here, in the internal thread processing by the cutting tap, chips are generated, so that a gap is formed between the complete thread portion and the internal thread formed on the workpiece in the internal thread plastic processing step. Then, chips enter the gap, and welding and adhesion are likely to occur. For this reason, it is preferable that the gap between the complete thread portion and the female screw formed on the workpiece is small.

  On the other hand, in the female thread processing by the raised tap 100, no chips are generated, and the gap between the thread of the complete thread portion 32 and the thread of the female thread formed on the workpiece in the plastic thread machining process. By forming a gap in the gap, the contact area between the thread of the complete thread portion 32 and the thread of the female thread formed on the workpiece can be reduced, so that the thread of the complete thread portion 32 and the workpiece can be reduced. It is possible to reduce the friction with the thread of the female screw formed on the surface. Further, since a gap is formed between the thread of the complete thread portion 32 and the thread of the female screw formed on the workpiece, the tapping oil can be spread over the gap. Thereby, the friction which arises in the contact part of the thread of the external thread part 30 and the internal thread formed in a to-be-processed object by the lubrication effect of tapping oil can be made small. Therefore, the processing torque in the plastic processing step of the female screw can be reduced to suppress welding or adhesion on the screw portion 30.

  Further, in the plastic working process of the female screw by the rising tap 100, the female screw of the workpiece plastically deformed by the biting portion 31 tries to return to the original shape, whereas the outer diameter of the second complete thread portion 32b. Is set smaller than the inner diameter of the pilot hole Ho, an increase in the contact area between the thread of the complete thread 32 and the thread of the female thread formed on the workpiece can be suppressed. The friction between the 32 threads and the thread of the female thread formed on the workpiece can be reduced, and as a result, the processing torque can be suppressed.

  In the present embodiment, the complete ridge portion 32 is formed of 14 ridges, and the number of screw threads of the first complete ridge portion 32a is constituted by three ridges, but is not necessarily limited thereto. However, it is preferable that the complete mountain portion 32 is formed of 8 or more threads, and the number of threads of the first complete mountain portion 32a is set to 2 or more and 4 or less.

  The number of threads of the first complete peak portion 32a is set to four or less while ensuring the guide property as the complete peak portion 32 by setting the number of threads of the first complete peak portion 32a to two or more. Thus, the contact area between the thread of the complete thread 32 and the female thread formed on the workpiece can be reduced. Therefore, while controlling the pitch error of the female screw to form a high-precision female screw, the friction with the female screw is suppressed to reduce the processing torque in the plastic processing step of the female screw, and the complete thread portion 32 (in particular, It is possible to suppress the occurrence of welding or adhesion in the first complete peak portion 32a).

  Furthermore, since the number of threads of the first complete thread portion 32a is set to 2 or more and 4 threads or less and the number of threads of the complete thread portion 32 is set to 8 or more, a long female screw is formed. Even in the case of forming a through hole, the thread of the second complete thread portion 32b is guided by the thread formed on the workpiece, thereby suppressing the processing torque and performing the plastic processing process of the female screw. It is possible to form a high-precision female screw while suppressing the pitch error of the female screw.

  Here, when measuring the effective diameter of the first complete thread portion 32a, at least three screw threads are required. However, after forming a screw thread having the same shape as the first complete thread portion 32a in the portion where the second complete thread portion 32b is formed, it is performed before the second complete thread portion 32b is removed. Even when the number of threads of the 1 complete thread portion 32a is 2 threads, the effective diameter of the first complete thread portion 32a can be measured.

  Next, with reference to FIG. 4, the processing torque measurement test of the build-up tap 100 will be described. FIG. 4 is a graph showing test results of the machining torque measurement test. In the machining torque measurement test, a workpiece is drilled under a predetermined condition, and the torque until the raised tap is removed from the workpiece is measured.

  The detailed specifications of the machining torque measurement test are as follows: work material: SCM440, hardness: 29 to 31 HRC, cutting speed: 10 m / min, rotation speed: 200 rotations per minute, pilot hole diameter: 15.3 mm, tapping Length: 24 mm, cutting fluid: water-insoluble, processing direction: vertical.

  Further, in the machining torque measurement test, the rising tap 100 (see FIG. 1, hereinafter referred to as “the product of the present invention”) having the number of lobes of 8 and the number of oil grooves of 8 explained in the present embodiment, and the same lobe as the product of the present invention. It is a rising tap of number 8 and number of oil grooves 8, and among the eight lobes, every other one in the circumferential direction, a processed product that has been processed into a total of four lobes, and the same number of lobes 8 as the present invention product And it was performed using the conventional product which has 8 oil grooves and all lobes are not subjected to the mountain-wiping process. The difference between the product of the present invention and the processed product and the conventional product is only the presence / absence of the mountain-wiping process or the position where the mountain-wiping process is performed. It is the same with goods.

  FIG. 4 is a graph showing test results of the machining torque measurement test, in which FIGS. 4 (a) to 4 (c) are the products of the present invention, FIGS. 4 (d) to 4 (f) are the processed products, and FIG. (G)-FIG.4 (i) have shown the maximum torque of the rise tap of the conventional product. FIG. 4 shows the results of the three tests performed on the three types of raised taps described above, and the left side (FIGS. 4A, 4D, and 4G) shows the first test. As a result, the center (FIG. 4 (b), FIG. 4 (e) and FIG. 4 (h)) is the second test result, and the right side (FIG. 4 (c), FIG. 4 (f) and FIG. 4 (i)) is. The results of the third test are shown. In the graph shown in FIG. 4, the vertical axis represents torque (Nm) and the horizontal axis represents time (s).

  As shown in FIG. 4, according to the test results of the processing torque measurement test, the average value of the maximum torque value of each test in the three tests was 0.3% lower than the conventional product in the processed product In contrast, the product of the present invention was 12.6% lower than the conventional product. The torque value of the conventional product and the processed product increases as the internal thread processing advances, whereas the torque value of the present product is almost flat, and the average value of the torque of the present product during internal thread processing is the same. Was smaller than the average torque of the processed product and the conventional product. In the processed product and the conventional product, the thread of the same shape is formed from the front end side to the rear end side in part or all of the lobe of the complete thread portion. Since the internal thread of the workpiece deformed plastically tries to return to its original shape, the contact area between the thread of the complete thread and the thread formed on the work increases as the rising tap is advanced. Thus, it is considered that the torque value increased with the progress of the internal thread machining, and as a result, the average value of the torque during the internal thread machining increased. On the other hand, in the product of the present invention, the chamfering process is performed so that the outer diameters of all the threads of the second complete thread portion 32b (see FIG. 3) have the above-described dimensions. Even if the internal thread of the workpiece is returned to its original state as it progresses, an increase in the contact area between the thread of the second complete thread portion 32b and the internal thread formed on the workpiece can be suppressed. It can be considered that screw processing is possible because the torque at the time of machining can be maintained at a substantially constant value so that screw machining is possible, and the average value of torque at the time of female screw machining is smaller than that of the machined product or the conventional product.

  In addition, the product of the present invention can reduce the torque when removing the raised tap from the workpiece after forming the female screw on the workpiece compared to the processed product and the conventional product, and stabilize the quality of the female screw. In addition, it is possible to suppress the occurrence of welding and adhesion when removing the raised tap from the workpiece.

  From the above results, it was confirmed that the build-up tap 100 can reduce the processing torque when all the screw threads of the second complete thread portion 32b are subjected to threading.

  As described above, the present invention has been described based on the embodiments, but the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention. It can be easily guessed.

  For example, in the above-described embodiment, a case has been described in which the tops of all the threads of the second complete thread portion 32b are threaded into a concentric arc shape when viewed in the direction of the axis O of the shank 20, but the present invention is not necessarily limited thereto. Instead, the tops of all the screw threads of the second complete thread portion 32 may be straight-lined when viewed in the direction of the axis O of the shank 20. In addition, you may perform the pile removal process in this case for every lobe along the axial center O direction.

100 Raised tap 20 Shank 30 Male thread portion 31 Chamfered portion 32 Complete crest portion 32a First complete crest portion 32b Second complete crest portion 40 Oil groove Ho Pilot hole D Dimension (Outer diameter of thread of first complete crest portion)
D1 dimension (outer diameter of screw thread of second complete thread)
H The height of Mt.

Claims (3)

A shank formed in a columnar shape, a chamfered portion disposed on the tip side of the shank and formed into a tapered shape, and a full threaded portion connected to the chamfered portion, and the male screw And an oil groove recessed in the outer peripheral surface of the part, and by causing the male thread part to bite into the surface layer part of the pilot hole provided in the work piece, the surface layer part of the pilot hole is plastically deformed to be a female screw. In the raised tap forming
The complete mountain portion includes a first complete mountain portion continuously provided to the biting portion, and a second complete mountain portion formed from the first complete mountain portion to the terminal on the shank side, The number of threads of the part is set to 8 or more,
The first complete thread part is set so that the number of threads is 2 or more and 4 or less,
In the second complete thread portion, the top of the screw thread is cut off, and the outer diameter of the second complete thread portion is set larger than the inner diameter of the female screw and smaller than the inner diameter of the pilot hole. Raised tap characterized by that. A shank formed in a columnar shape, a chamfered portion disposed on the tip side of the shank and formed into a tapered shape, and a full threaded portion connected to the chamfered portion, and the male screw And an oil groove recessed in the outer peripheral surface of the part, and by causing the male thread part to bite into the surface layer part of the pilot hole provided in the work piece, the surface layer part of the pilot hole is plastically deformed to be a female screw. In the raised tap forming
The complete mountain portion includes a first complete mountain portion continuously provided to the biting portion, and a second complete mountain portion formed from the first complete mountain portion to the terminal on the shank side, The number of threads of the part is set to 8 or more,
The first complete thread part is set so that the number of threads is 2 or more and 4 or less,
The second complete thread part has a thread chamfered at the top of the thread, and the outer diameter D of the thread of the first complete thread part and the height H of the point thread of the complete thread part are The raised tap characterized by the outer diameter of the thread of a 2nd complete thread part being (D- (3/4) H-0.2H) or more and less than (D- (3/4) H).   3. The raised tap according to claim 1, wherein all the screw threads of the second complete thread part are processed to be concentric arcs when viewed in the axial direction of the shank.

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