JP2011005593A - Tap set, screw hole working device and screw hole working method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tap set which can highly accurately and easily form a thread hole with a large diameter, a screw hole working device and a screw hole working method.SOLUTION: A first tap 50 is rotated and screwed into a prepared hole H previously formed in an object A to be worked to form a tap path 54 in a part of a wall surface including an opening end E of the prepared hole H. Then, a second tap 60 is rotated and screwed into the prepared hole H along the tap path 54 to form a primary internal thread 64 on an entire part of the wall surface of the prepared hole H. Then, a third tap 70 is rotated and screwed into the prepared hole H along the primary internal thread 64 to finish the primary internal thread 64 and form an internal thread 74 over the entire part of the wall surface of the prepared hole H.

Description

  The present invention relates to a tap set, a screw hole processing device, and a screw hole processing method for performing screw hole processing on an object in which a pilot hole is formed.

  Conventionally, screw parts are used as fastening members between machine parts in various fields. And formation of the internal thread to a machine part is generally performed using the tap which has a thread for cutting an internal thread.

  For example, when making a steam turbine, bolts are used to fasten the upper and lower casings. Therefore, after making a pilot hole in the casing and screwing it while rotating the tap with respect to the pilot hole, Need to form.

  Various types of taps have been proposed. For example, Patent Literature 1 discloses a tap provided with a guide for guiding the tap body along the axis of the pilot hole at the tip.

  Patent Document 2 discloses a screw hole machining device in which a torque amplifier (deceleration mechanism) that amplifies the torque transmitted to the rotating shaft is attached to the output shaft side of the motor from the viewpoint of facilitating screw hole machining. Has been.

Japanese Utility Model Publication No. 63-86928 JP 2001-328026 A

  However, as the size of the screw hole to be formed increases, the torque required for screw hole processing increases, and the reaction force received by the tap during screw hole processing increases, and the screw hole processing accuracy (straightness of the tap) Decreases.

  For this reason, even if it uses the tap with a guide described in patent documents 1, it may be unable to transmit sufficient torque to a tap, or it may be unable to support the reaction force which a tap receives with a guide. It is difficult to form a screw hole with sufficient processing accuracy.

  In addition, even if the screw hole processing device with a speed reduction mechanism described in Patent Document 2 is used, the rectilinear force of the tap is impaired by the reaction force at the time of screw hole processing, so a large diameter screw hole is formed with sufficient processing accuracy. Difficult to do.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a tap set, a screw hole processing apparatus, and a screw hole processing method capable of easily forming a large-diameter screw hole with high accuracy. .

  The screw hole processing method according to the present invention is a screw hole processing method for performing screw hole processing on an object in which a pilot hole is formed, and a guide having a smaller diameter than the pilot hole is provided on the tip side, A step of forming a tap path in a part of the wall surface including the opening end of the pilot hole by a first tap provided with a first screw thread on a base end side, and a second tap provided with a second screw thread And a step of forming a primary female screw on the wall surface of the pilot hole along the tap path, and a step of finishing the primary female screw by a third tap provided with a third screw thread. It is characterized by that.

  According to this screw hole machining method, the formation of the tap path, the formation of the primary female screw, and the finishing process can be performed in stages, and the torque required at each stage of the screw hole machining can be reduced.

  In addition, by reducing the torque required at each stage of screw hole processing, the reaction force received by the tap is reduced, and the shaft shaft shake caused by the reaction force is suppressed, and the screw hole processing accuracy is improved. Can do.

  Furthermore, since the guide is provided on the tip side of the first tap, the tap path can be formed with high accuracy, and the formation of the primary female screw by the subsequent second tap and the finishing process by the third tap are accurate. Can be done well.

  Therefore, according to the screw hole machining method, a large-diameter screw hole can be easily formed with high accuracy.

  The tap set according to the present invention is a tap set for performing threaded hole processing on an object in which a pilot hole is formed, and a guide having a smaller diameter than the pilot hole is provided on the tip side, and A first tap in which a first thread that forms a tap path in a part of the wall surface including the open end is provided on the base end side, and a first female thread is formed on the wall surface of the pilot hole along the tap path. And a second tap provided with a second thread and a third tap provided with a third thread for finishing the primary female thread.

  In order to form the female screw using the tap set, a tap path is formed on a part of the wall surface of the pilot hole using the first tap, and a primary female is formed on the wall surface of the pilot hole along the tap path by the second tap. After forming the screw, the finishing process of the primary female screw may be performed by the third tap.

  As described above, by using the tap set, the formation of the tap path, the formation of the primary female screw, and the finishing process are performed in stages, so that the torque required at each stage of the screw hole processing can be reduced.

  In addition, by reducing the torque required at each stage of screw hole processing, the reaction force received by the tap is reduced, and the shaft shaft shake caused by the reaction force is suppressed, and the screw hole processing accuracy is improved. Can do.

  Furthermore, since the guide is provided on the tip side of the first tap, the tap path can be formed with high accuracy, and the formation of the primary female screw by the subsequent second tap and the finishing process by the third tap are accurate. Can be done well.

  Therefore, if the tap set is used, a large-diameter screw hole can be easily formed with high accuracy.

In the tap set, the diameter D ₁ and the length L ₁ of the guide of the first tap preferably satisfy a relationship of 0.25 ≦ L ₁ / D ₁ ≦ 1.5.

Guide length _{L 1} by more than 0.25 times the diameter _{D 1 (L 1 / D 1} ≧ 0.25), the shaft wobble of the first tapped during screwing into the prepared hole of the first tab Suppressing reliably, a large-diameter screw hole can be formed with higher accuracy. Further, by the guide of a length _{L 1} than 1.5 times the diameter _{D 1 (L 1 / D 1} ≦ 1.5), it is possible to reduce the weight of the first tap.

  In the tap set, the pitch number of the first thread of the first tap is preferably 4 or more and 9 or less.

  By setting the number of pitches of the first threads to 4 or more, a tap path for guiding the second tap with sufficient accuracy can be formed on the prepared hole wall surface. Moreover, the torque required for screwing in the first tap can be reduced by setting the number of pitches of the first thread to 9 or less.

  The screw hole machining device according to the present invention includes a tap fixing portion in which one of the tap sets is fixed in a replaceable manner, and a rotation shaft that rotates integrally with the one tap via the tap fixing portion. It is characterized by providing.

  According to this threaded hole processing apparatus, the first tap, the second tap, and the third tap are fixed to the tap fixing portion in order, and the threaded hole processing is performed, thereby forming the tap path, forming the primary female thread, and finishing processing. Can be carried out step by step to reduce the required torque at each stage of threaded hole machining.

  In addition, by reducing the torque required at each stage of screw hole processing, the reaction force received by the tap is reduced, and the shaft shaft shake caused by the reaction force is suppressed, and the screw hole processing accuracy is improved. Can do.

  Furthermore, since the guide is provided on the tip side of the first tap, the tap path can be formed with high accuracy, and the formation of the primary female screw by the subsequent second tap and the finishing process by the third tap are accurate. Can be done well.

  Therefore, according to the screw hole processing apparatus, a large-diameter screw hole can be easily formed with high accuracy.

  The screw hole machining device preferably further includes a torque amplifier that amplifies the torque transmitted to the rotating shaft.

  This makes it easier to form a large-diameter screw hole. For example, if a torque amplifier having a torque amplification ratio of 12 times or more is used, a screw hole of M100 or more can be manually formed.

  The screw hole processing device preferably further includes a slide bearing that rotatably supports the rotating shaft.

  Thereby, the axial blurring of the rotating shaft at the time of screw hole processing can be prevented, and the screw hole can be formed with high accuracy.

In the screw hole machining apparatus, it is preferable that the length L _{2 of the} plain bearing and the diameter D _{2 of the} rotating shaft satisfy a relationship of 1 ≦ L ₂ / D ₂ ≦ 2.

  As a result, it is possible to reliably prevent the shaft shake of the rotating shaft during the screw hole machining and to form the screw hole with higher accuracy.

  According to the present invention, the first tap, the second tap, and the third tap are used to form a tap path, a primary female screw, and a finishing process step by step, so that the torque required at each stage of screw hole machining Can be reduced.

  In addition, by reducing the torque required at each stage of screw hole processing, the reaction force received by the tap is reduced, and the shaft shaft shake caused by the reaction force is suppressed, and the screw hole processing accuracy is improved. Can do.

  Furthermore, since the guide is provided on the tip side of the first tap, the tap path can be formed with high accuracy, and the formation of the primary female screw by the subsequent second tap and the finishing process by the third tap are accurate. Can be done well.

  Therefore, according to the present invention, a large-diameter screw hole can be easily formed with high accuracy.

It is a perspective view which shows the structural example of a screw hole processing apparatus. It is sectional drawing which shows the structural example of the tap of a screw hole processing apparatus. It is sectional drawing which shows the structure of the tap periphery of a screw hole processing apparatus. It is a disassembled perspective view which shows the structural example of a torque amplifier. It is sectional drawing which shows an example of a tap set, (a)-(c) is a figure which shows the structural example of a 1st tap, a 2nd tap, and a 3rd tap, respectively. It is sectional drawing which shows the relationship between a pilot hole and a 1st tap. It is a figure which shows a mode that a screw hole process is performed using a tap set. It is sectional drawing which shows the other example of a 1st tap. It is a figure which shows a mode that a screw hole process is performed using the tap set containing the 1st tap of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a perspective view showing a configuration example of a screw hole machining apparatus according to the present invention. FIG. 2 is a cross-sectional view illustrating a configuration example of the tap of the screw hole machining apparatus. FIG. 3 is a cross-sectional view showing the configuration around the tap of the screw hole machining apparatus. FIG. 4 is an exploded perspective view showing a configuration example of a torque amplifier used in the screw hole machining apparatus.

  The screw hole machining apparatus 1 shown in FIG. 1 mainly includes a tap fixing portion 10 in which the tap T is fixed in a replaceable manner, a rotating shaft 12 that rotates integrally with the tap T via the tap fixing portion 10, and rotation. The support portion 20 that supports the shaft 12, the input portion 14 that inputs rotation to the rotary shaft 12, the torque amplifier 30 that amplifies the torque of the input portion 14, and the reaction force receiving portion 40 that prevents the torque amplifier 30 from rotating. It consists of.

  The tap T is one of the tap sets according to the present invention. As shown in FIG. 2, the tap T is a thread 2 for cutting a female screw in a prepared hole formed in a workpiece, and is generated at the time of cutting. And a groove 3 for discharging chips. As shown in FIG. 3, the tap T is provided with a tap shank S on the side opposite to the workpiece A, and the tap shank S is held by the tap fixing portion 10. The configuration of the tap T (that is, the configuration of the tap set) will be described later in detail.

  The tap fixing part 10 has a tap chuck part 10A into which the tap shank S of the tap T is inserted. The tap chuck portion 10A is configured in the same shape as the tap shank S, and the tap shank S is inserted therein. From the viewpoint of securely fixing the tap shank S, the tap chuck portion 10A is preferably a square hole. The tap T can be fixed to the tap fixing portion 10 by, for example, tightening with a bolt in a state where the tap shank S is inserted into the tap chuck portion 10A.

  Further, the tap fixing portion 10 is provided with a shaft chuck portion 10B for fixing the shaft shank 13 of the rotary shaft 12 on the side opposite to the tap chuck portion 10A. As with the tap chuck portion 10A, the shaft chuck portion 10B is also preferably a square hole from the viewpoint of securely fixing the shaft shank 13. The rotation shaft 12 can be fixed to the tap fixing portion 10 by, for example, tightening with a bolt while the shaft shank 13 is fitted in the shaft chuck portion 10B.

  The rotary shaft 12 may receive a reaction force at the time of screw hole processing and cause shaft blurring. Shaft blurring of the rotating shaft 12 hinders straight advanceability of the tap T during screw hole machining and causes a reduction in screw hole machining accuracy. Therefore, a support portion that supports the rotating shaft 12 so as not to cause shaft blurring. 20 is preferably provided.

  As shown in FIG. 1, the support unit 20 includes a pedestal 22 fixed to the workpiece A, a plurality of support columns 24 erected on the pedestal 22, a flange 26 supported by the support columns 24, and a flange 26. The bearing 28 is fixed and supports the rotary shaft 12 rotatably. By providing the support portion 20, the shaft shake of the rotating shaft 12 can be suppressed by the bearing 28, the straightness of the tap T at the time of screw hole processing can be secured, and the screw hole processing accuracy can be improved.

  The bearing 28 may be a sliding bearing or a rolling bearing, but a sliding bearing capable of supporting the rotating shaft 12 in a large area is preferable in that wear of the rotating shaft 12 can be prevented. In particular, it is preferable to use an oil-impregnated bearing that does not require replenishment of lubricating oil as the bearing 28.

The length L ₂ of the bearing 28 and the diameter D ₂ of the rotating shaft 12 preferably satisfy the relationship 1 ≦ L ₂ / D ₂ ≦ 2. Thereby, the axial blurring of the rotating shaft 12 at the time of screw hole processing can be reliably prevented, and the screw hole can be formed with higher accuracy.

  The rotation shaft 12 is connected to the input portion 14 at the end opposite to the end portion (the shaft shank 13 shown in FIG. 3) fixed to the tap fixing portion 10, and rotates as the input portion 14 rotates. It is supposed to be.

  The input unit 14 is not particularly limited as long as the rotating shaft 12 can be rotated. For example, a tap handle or an electric motor can be used. However, when an electric motor is used as the input unit 14, although a large diameter screw up to about M100 can be handled, a transformer for power supply may be required at a site where screw hole machining is performed. Therefore, it is preferable to use a tap handle for the input unit 14 as a simple configuration that does not require a power transformer. FIG. 1 shows an example in which a tap handle is used as the input unit 14.

  However, when screw hole processing is manually performed using a tap handle as the input unit 14, a sufficient torque cannot be transmitted to the tap T, and depending on the material of the screw, formation or size increase of the female screw exceeding M30 may occur. It can be difficult. In particular, the formation of female threads exceeding M100 cannot be handled with a portable drilling machine, and it has been usual to use large machine tools. However, due to restrictions on the work space at the site, large machine tools have been used. In some cases, the machine could not be carried to the site. Therefore, in order to eliminate the torque shortage of the tap handle, it is preferable to use a torque amplifier 30 as shown in FIG.

  As shown in FIG. 4, the torque amplifier 30 includes an input shaft 32 connected to the input unit side, a first gear set 34 and a second gear set 36 that amplify the torque of the input shaft 32, and the amplified torque on the rotating shaft. And an output shaft 38 to be transmitted to the side.

  A known speed reduction mechanism can be used for the first gear set 34 and the second gear set 36. For example, the first gear set 34 includes a sun gear 34A, a planetary gear 34B disposed around the sun gear 34A, and a ring gear 34C having internal teeth that mesh with the planetary gear 34B, as shown in FIG. May be. Similarly, the second gear set 36 may include a sun gear 36A, a planetary gear 36B disposed around the sun gear 36A, and a ring gear 36C having internal teeth that mesh with the planetary gear 36B.

  The torque amplification ratio (= output torque / input torque) of the torque amplifier 30 may be appropriately adjusted according to the diameter of the screw hole and the material of the object to be processed so as to obtain the torque necessary for the screw hole processing. preferable. Thereby, for example, by using the torque amplifier 30 having a torque amplification ratio of 12 times or more, a large-diameter screw hole exceeding M100 can be manually formed (tap handle).

  FIG. 4 shows a mode in which the first gear set 34 and the second gear set 36 are used to perform two-stage torque amplification (deceleration) and output to the rotating shaft side. However, how many stages of torque amplification are performed? Also good.

  When the torque amplifier 30 is used as described above, it is necessary to provide the reaction force receiving portion 40 that prevents the torque amplifier 30 from rotating around. The reaction force receiving portion 40 is not particularly limited as long as it can be prevented from rotating with the torque amplifier 30. For example, as shown in FIG. 1, a reaction force receiving plate 42 extending from the torque amplifier 30 and a processing A support bar 44 standing on the object A and a fixing member 46 for connecting and fixing the reaction force receiving plate 42 and the support bar 44 can be used.

  Next, the tap T used for the above-described screw hole machining apparatus 1 will be described. FIG. 5 is a cross-sectional view showing an example of the structure of a tap set used in the present embodiment, and FIGS. 5A to 5C show configuration examples of the first tap, the second tap, and the third tap, respectively. It is sectional drawing. FIG. 6 is a cross-sectional view showing the relationship between the first tap of the tap set shown in FIG. 5 and the pilot hole of the workpiece.

  In the present embodiment, in order to perform screw hole machining, a tap set including three types of taps illustrated in FIGS. 5A to 5C is used.

  A first tap 50 shown in FIG. 5A is provided on the distal end side, a guide G for guiding the main body B of the first tap 50 to the pilot hole, a triangular thread 52 provided on the proximal end side, and a tap. And a tap shank S held by the fixing unit 10. The first tap 50 is configured such that the diameter gradually decreases from the region where the triangular thread 52 of the first tap is provided to the region where the guide G is provided.

  The second tap 60 shown in FIG. 5B includes a trapezoidal screw thread 62 provided in almost the entire region including the tip side, and a tap shank S held by the tap fixing part 10.

  The third tap 70 shown in FIG. 5C includes a triangular thread 72 provided in almost the entire region including the tip side, and a tap shank S held by the tap fixing part 10.

  The pitches (52, 62, 72) of the first tap 50, the second tap 60, and the third tap 70 have substantially the same pitch and thread angle, and the diameter of each valley is substantially the same as the diameter of the pilot hole. Are the same.

As illustrated in FIG. 6, the diameter D ₁ of the guide G of the first tap 50 is slightly smaller than the diameter D of the pilot hole H of the workpiece A. Dimensional tolerances between the diameter D of the diameter D ₁ and the lower hole H of the guide G, in order to ensure an appropriate clearance, Japanese Industrial Standards (JIS B0401-2) defined is preferably determined along the. For example, if the dimensional tolerance of the guide G of the first tap 50 is set to g6 and the dimensional tolerance of the pilot hole H is set to H7, an appropriate gap can be secured.

The diameter D ₁ and the length L ₁ of the guide G of the first tap 50 preferably satisfy the relationship of 0.25 ≦ L ₁ / D ₁ ≦ 1.5. Guide G the length _{L 1} by more than 0.25 times the diameter _{D 1 (L 1 / D 1} ≧ 0.25), and reliably suppress axial vibration of the first tap 50 at threaded hole machining Thus, the straightness of the first tap 50 can be reliably maintained. Further, by the guide G the length _{L 1} than 1.5 times the diameter _{D 1 (L 1 / D 1} ≦ 1.5), it is possible to reduce the weight of the first tap 50.

  In addition, the number of pitches (the number of threads) of the triangular thread 52 of the first tap 50 is preferably 4 or more and 9 or less. By setting the pitch number of the triangular thread 52 to 4 or more, a tap path for guiding the second tap 60 with sufficient accuracy can be formed on the prepared hole wall surface. Moreover, the torque required for screwing in the first tap 50 can be reduced by setting the pitch number of the triangular thread 52 to 9 or less. In the present specification, the “pitch number (number of threads)” of the triangular thread 52 is not only a complete triangular thread, but also a trapezoidal thread that is cut off near the apex of the triangular thread ( That is, the number of pitches (the number of threads) including the thread provided in the region where the diameter of the first tap 50 gradually decreases.

  Next, a method for performing screw hole machining using the above-described tap set will be described. FIG. 7 is a diagram illustrating a state in which screw hole machining is performed using the above-described tap set.

  As shown in FIG. 7A, the first tap 50 is screwed into the prepared hole A formed in advance in the workpiece A while being rotated. As a result, the tap path 54 (see FIG. 7B) is formed in a part of the wall surface including the opening end E of the pilot hole H.

  Next, as shown in FIG. 7B, the second tap 60 is screwed into the pilot hole H while rotating the second tap 60 along the tap path 54 formed by the first tap 50. Thereby, the primary internal thread 64 (refer FIG.7 (c)) is formed in the whole wall surface of the pilot hole H. FIG.

  Thereafter, as shown in FIG. 7C, the third tap 70 is screwed into the pilot hole H while being rotated along the primary female screw 64 formed by the second tap 60. Thereby, the finishing process of the primary female screw 64 formed on the entire wall surface of the pilot hole H can be performed, and the female screw 74 can be formed over the entire wall surface of the pilot hole H.

  Thus, using the first tap 50, the second tap 60, and the third tap 70, the tap path 54, the primary female screw 64, and the finishing process (formation of the female screw 74) are performed in stages. Thus, it is possible to reduce the torque required at each stage of screw hole machining.

  In addition, the torque required at each stage of screw hole processing is reduced, so that the reaction force received by the tap is reduced, and the axial blurring of the tap (50, 60, 70) due to the reaction force is suppressed, and the screw Hole machining accuracy can be improved.

  Further, since the guide G is provided on the tip side of the first tap 50, the tap path 54 can be formed with high accuracy, and the formation and finishing of the subsequent primary female screw 64 (formation of the female screw 74). ) Can be performed with high accuracy.

  Therefore, according to the above-described screw hole machining method, even a large-diameter screw hole can be formed with high accuracy and easily.

  Although an example of the present invention has been described in detail above, the present invention is not limited to this, and it goes without saying that various improvements and modifications may be made without departing from the gist of the present invention.

  For example, in the above-described embodiment, the tap path 54, the formation of the primary female screw 64, and the finishing process are performed by using a tap set including three kinds of taps of the first tap 50, the second tap 60, and the third tap 70. An example in which screw hole machining is performed in three stages (formation of female screw 74) has been described. However, the tap set according to the present invention only needs to include at least the first tap 50, the second tap 60, and the third tap 70, and may include four or more types of taps.

  In particular, if a tap set to which a fourth tap provided with a trapezoidal screw thread having an outer diameter larger than that of the second tap 60 is used is used, after the primary female screw 64 is formed by the second tap 60, the secondary tap is used by the fourth tap. By forming the female screw, the torque required for finishing by the subsequent third tap 70 can be further reduced.

  Moreover, although the above-mentioned embodiment demonstrated the example using the tap set containing the 1st tap 50 in which the triangular thread 52 was provided, the trapezoidal thread may be sufficient as the thread of the 1st tap 50.

  FIG. 8 is a cross-sectional view showing a first tap provided with a trapezoidal thread. FIG. 9 is a diagram illustrating a state in which screw hole machining is performed using the tap set including the first tap illustrated in FIG. 8.

  As shown in FIG. 8, the first tap 80 is provided on the distal end side, the guide G for guiding the main body B of the first tap 80 to the pilot hole, the trapezoidal screw thread 82 provided on the proximal end side, and the tap And a tap shank S held by the fixing unit 10. If the first tap 80 is used, a tap path for guiding the second tap 60 can be formed with a small torque. The first tap 80 has the same configuration as that of the first tap 50 except that the triangular thread 52 is changed to a trapezoidal thread 82, and the description of the configuration that is common to the first tap 50 is omitted here. .

  When screw hole processing is performed using a tap set including the first tap 80, the second tap 60, and the third tap 70, first, as shown in FIG. The first tap 80 is screwed into the prepared hole H while rotating. Thereby, the tap path 84 (refer FIG.9 (b)) is formed in a part of wall surface including the opening end E of the pilot hole H. FIG. Here, the tap path 84 is a trapezoidal female screw, and is different from the tap path 54 (see FIG. 7B) which is a triangular female screw. Since the subsequent procedure is the same as the procedure shown in FIGS. 7B to 7D as shown in FIGS. 9B to 9D, the description thereof is omitted here.

  Further, in the above-described embodiment, the example using the tap set including the second tap 60 provided with the trapezoidal thread 62 and the third tap 70 provided with the triangular thread 72 has been described. The thread shapes of the 60 and the third tap 70 are not limited to this example. That is, the threads of the second tap 60 and the third tap 70 have substantially the same pitch, and the diameter of each valley is substantially the same as the diameter of the pilot hole. It is sufficient that the protrusion length (the height of the thread) is smaller than the thread of the third tap 70, and various shapes can be adopted. For example, the thread of the second tap and the third tap are both composed of triangular threads, and the protrusion length (the height of the thread) of the second tap 60 is greater than the thread of the third tap 70. (That is, the thread angle of the second tap 60 may be larger than the thread of the third tap 70).

DESCRIPTION OF SYMBOLS 1 ... Screw hole processing apparatus 10 ... Tap fixing | fixed part 10A ... Tap chuck | zipper part 10B ... Shaft chuck part 12 ... Rotating shaft 13 ... Shaft shank 14 ... Input part 20 ... Support part 22 ... Base 24 ... Support | pillar 26 ... Flange 28 ... Bearing 30 ... Torque amplifier 32 ... Input shaft 34 ... First gear set 36 ... Second gear set 34A, 36A ... Sun gear,
34B, 36B ... Planetary gear 34C, 36C ... Ring gear 38 ... Output shaft 40 ... Reaction force receiving portion 42 ... Reaction force receiving plate 44 ... Support rod 46 ... Fixing member 50 ... First tap 52 ... Triangular thread 54 ... Tap path 60 ... 2nd tap 62 ... Trapezoidal thread 64 ... Primary female thread 70 ... 3rd tap 72 ... Triangular thread 74 ... Female thread 80 ... 1st tap 82 ... Trapezoidal thread 84 ... Tap path A ... Work object B ... Tap body G ... Guide H ... Pilot hole S ... Tap shank

Claims (8)

A screw hole processing method for performing screw hole processing on an object in which a pilot hole is formed,
A guide having a smaller diameter than the pilot hole is provided on the distal end side, and a tap path is formed on a part of the wall surface including the opening end of the pilot hole by the first tap provided with the first screw thread on the proximal end side. And a process of
Forming a primary female screw on the wall surface of the pilot hole along the tap path by a second tap provided with a second thread;
And a step of finishing the primary female screw by a third tap provided with a third screw thread. It is a tap set that performs screw hole processing on an object in which a pilot hole is formed,
A guide having a diameter smaller than that of the pilot hole is provided on the distal end side, and a first tap is provided on the proximal end side of the first screw thread that forms a tap path in a part of the wall surface including the opening end of the pilot hole. ,
A second tap provided with a second thread that forms a primary female thread on the wall surface of the pilot hole along the tap path;
A tap set comprising: a third tap provided with a third thread for finishing the primary female screw. 3. The tap set according to claim 2, wherein a diameter D ₁ and a length L ₁ of the guide of the first tap satisfy a relationship of 0.25 ≦ L ₁ / D ₁ ≦ 1.5.   The tap set according to claim 2 or 3, wherein the number of pitches of the first thread of the first tap is 4 or more and 9 or less. A tap fixing part in which one tap of the tap set according to any one of claims 2 to 4 is fixed in a replaceable manner;
A screw hole machining apparatus comprising: a rotary shaft that rotates integrally with the one tap via the tap fixing portion.   The screw hole machining apparatus according to claim 5, further comprising a torque amplifier that amplifies torque transmitted to the rotating shaft.   The screw hole machining device according to claim 5, further comprising a slide bearing that rotatably supports the rotating shaft. The screw hole processing device according to claim 7, wherein a length L _{2 of the} sliding bearing and a diameter D _{2 of the} rotating shaft satisfy a relationship of 1 ≦ L ₂ / D ₂ ≦ 2.

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