JP6616991B2 - Drilling method - Google Patents

Description

  The present invention relates to a hole machining method.

  In the processing of workpieces, finishing is often performed after roughing. Different tools are used in the roughing process and the finishing process (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 06-106470

  The use of different tools can cause harm. For example, when a hole having a straight part and a spherical bottom part is formed using different tools, a step is formed at the boundary between the straight part and the bottom part due to the difference in the tool, or the inner surface of the hole Asperities may be formed on the surface.

  An object of this invention is to provide the hole drilling method which can suppress the fall of a machining precision, even when using a several different tool.

  The present invention includes a first tool having a first blade fixed to the first body and the first body and having a first blade disposed at a predetermined distance from the first central axis of the first body in the radial direction, and a workpiece. A hole forming step of forming a hole including a straight portion having a diameter corresponding to the predetermined distance in the workpiece, at least a part of which is fixed to the second body and the second body. A second tool having a second blade disposed at the predetermined distance from the second central axis of the second body with respect to the direction is inserted into the hole, and the second tool and the workpiece are relatively rotated. A roughing step of roughing the bottom of the hole, and a third body and at least a portion fixed to the third body and disposed at the predetermined distance from the third central axis of the third body in the radial direction. A third tool having a third blade; Is inserted into the third and relatively rotating the tool and said workpiece, said bottom to provide a hole machining method comprising finishing step of finishing to be spherical, the.

  According to the present invention, the straight portion of the hole is formed using the first blade of the first tool, the bottom portion of the hole is rough processed using the second blade of the second tool, and the third blade of the third tool is used. Used to finish the bottom of the hole. The first blade is disposed at a predetermined distance from the first central axis of the first body, the second blade is disposed at a predetermined distance from the second central axis of the second body, and the third blade is the third central axis of the third body. Is arranged at a predetermined distance. That is, in each tool, the distance from the central axis is the same for the first blade, the second blade, and the third blade. Therefore, the formation of a step at the boundary between the straight portion and the bottom portion is suppressed. Moreover, in each tool, since the distance of the 2nd blade and the distance of the 3rd blade from the center axis are equal to the distance of the 1st blade, the 2nd body and the 3rd body are bent or run out in the roughing process and the finishing process. And the bottom of the hole is formed with high processing accuracy. Further, since the formation of the step is suppressed and the spherical bottom is formed with high surface accuracy, the stress concentration on the inner surface of the hole is suppressed. Therefore, a high-quality workpiece can be provided.

  In the present invention, the distance from the first central axis of the first body to the first blade refers to the first central axis and the outermost portion (outermost diameter portion) of the first blade in the radial direction with respect to the first central axis. ). When there are a plurality of first blades, the outermost diameter portion of the first blade refers to the outermost portion of the plurality of first blades in the radial direction with respect to the first central axis. Similarly, the distance from the second central axis of the second body to the second blade refers to the second central axis and the outermost portion (outermost diameter portion) of the second blade in the radial direction with respect to the second central axis. When there are a plurality of second blades, the outermost diameter portion of the second blade refers to the outermost portion in the radial direction with respect to the second central axis among the plurality of second blades. The distance from the third central axis of the third body to the third blade is the distance between the third central axis and the outermost portion (outermost diameter portion) of the third blade in the radial direction with respect to the third central axis. In the case where there are a plurality of third blades, the outermost diameter portion of the third blade refers to the outermost portion of the plurality of third blades in the radial direction with respect to the third central axis.

  In the present invention, in the cross section including the second central axis, it is preferable that the second blade has a plurality of linear portions. By forming the second blade with a straight portion, the occurrence of self-excited vibration (chatter) is suppressed, and rough machining can be performed at high speed.

  In the present invention, in the cross section including the third central axis, the third blade has an arc portion and a linear portion, and at least a part of the arc portion of the third blade is on the third central axis. It is preferable that the linear portion of the third blade is disposed so as to be inclined with respect to the third central axis from the third central axis toward the outside in the radial direction. When the third blade has an arc portion, a spherical bottom portion can be formed. Moreover, the part which cross | intersects a 3rd center axis | shaft among bottom parts is a part with a low relative rotational speed with a 3rd tool, and it is hard to process it, and possibility that a projection part will remain becomes high. By disposing at least a part of the arc portion on the third central axis, the portion of the bottom that intersects the third central axis is processed by the arc portion of the third blade. Therefore, the remaining protrusions are suppressed, and the bottom can be finished in a spherical shape.

  In the present invention, the first tool includes a first pad member having a surface disposed at the predetermined distance from the first central axis with respect to a radial direction, and the first pad is formed in at least a part of the hole forming step. It is preferable that the surface of the member is in contact with the inner surface of the straight portion. When the first pad member whose distance from the first central axis is equal to the outermost diameter portion of the first blade is in contact with the inner surface of the hole of the straight portion, the first body is bent in forming the hole by the first blade. Swinging is suppressed. Accordingly, the straight portion of the hole is formed with high processing accuracy. Further, after the hole formation by the first blade is completed, when the first tool is pulled out from the hole, the first pad member whose distance from the first central axis is equal to the outermost diameter portion of the first blade is formed on the inner surface of the straight portion. Since it contacts, the 1st tool can be pulled out, suppressing a bending or a deflection of the 1st body. Therefore, the first blade is suppressed from biting into the inner surface of the straight portion, and damage to the inner surface of the straight portion is suppressed.

  In the present invention, the second tool includes a second pad member having a surface disposed at the predetermined distance from the second central axis with respect to a radial direction, and in the roughing step, the second tool includes a surface of the second pad member. It is preferable that the bottom portion is roughly processed with the second blade in a state where the inner surface of the straight portion is in contact. When the second pad member whose distance from the second central axis is equal to the outermost diameter portion of the second blade is in contact with the inner surface of the hole of the straight portion, the second body is bent in rough machining by the second blade. Swinging is suppressed. Therefore, rough machining of the bottom of the hole is stably performed. When the second tool is pulled out from the hole after the roughing by the second blade is finished, the second pad member whose distance from the second central axis is equal to the outermost diameter portion of the second blade is formed on the inner surface of the straight portion. Since it contacts, the 2nd tool can be pulled out, suppressing the bending or deflection of the 2nd body. Therefore, the second blade is prevented from biting into the inner surface of the straight portion, and damage to the inner surface of the straight portion is suppressed.

  In the present invention, the third tool includes a third pad member having a surface disposed at the predetermined distance from the third central axis with respect to a radial direction. In the finishing step, the third tool and the surface of the third pad member It is preferable to finish the bottom portion with the third blade in a state where the inner surface of the straight portion is in contact. When the third pad member whose distance from the third central axis is equal to the outermost diameter portion of the third blade is in contact with the inner surface of the hole of the straight portion, the third body is bent in the finishing process by the third blade. Swinging is suppressed. Therefore, the finishing of the bottom of the hole is performed with high processing accuracy. Further, when the third tool is pulled out from the hole after finishing with the third blade, the third pad member whose distance from the third central axis is equal to the outermost diameter portion of the third blade is formed on the inner surface of the straight portion. Since the contact is made, the third tool can be pulled out while suppressing the bending or deflection of the third body. Therefore, the third blade is prevented from biting into the inner surface of the straight portion, and damage to the inner surface of the straight portion is suppressed.

  In the present invention, the distance from the first central axis of the first body to the first pad member refers to the first central axis and the outermost portion (outermost part) of the first pad members in the radial direction with respect to the first central axis. The distance to the diameter part). When there are a plurality of first pad members, the outermost diameter portion of the first pad member refers to the outermost portion of the plurality of first pad members in the radial direction with respect to the first central axis. Similarly, the distance from the second central axis of the second body to the second pad member refers to the second central axis and the outermost portion (outermost diameter) of the second pad member in the radial direction with respect to the second central axis. Part), and when there are a plurality of second pad members, the outermost diameter part of the second pad member is the outermost part of the plurality of second pad members in the radial direction with respect to the second central axis. Say. The distance from the third central axis of the third body to the third pad member refers to the third central axis and the outermost portion (outermost diameter portion) of the third pad member in the radial direction with respect to the third central axis. In the case where there are a plurality of third pad members, the outermost diameter portion of the third pad member is the outermost portion in the radial direction with respect to the third central axis among the plurality of third pad members.

  In the present invention, it is preferable that the hole is a deep hole in which the straight portion is longer than 500 mm, and the workpiece subjected to the finishing process is used for a drive shaft housing of a nuclear reactor. As a result, a high-quality drive shaft housing with reduced stress concentration is provided.

  ADVANTAGE OF THE INVENTION According to this invention, even when using a several different tool, the drilling method which can suppress the fall of a machining precision is provided.

FIG. 1 is a diagram schematically illustrating a hole processing apparatus according to the present embodiment. FIG. 2 is a flowchart showing the hole machining method according to this embodiment. FIG. 3 is a view showing the first tool used in the hole forming step according to the present embodiment. FIG. 4 is a cross-sectional view showing the workpiece after the hole forming step according to this embodiment is completed. FIG. 5 is a diagram showing a second tool used in the roughing process according to the present embodiment. FIG. 6 is a cross-sectional view showing the workpiece after the rough machining step according to the present embodiment has been completed. FIG. 7 is a view showing a third tool used in the finishing process according to the present embodiment. FIG. 8 is an enlarged view of a part of the third tool according to the present embodiment. FIG. 9 is a cross-sectional view showing the workpiece after the finishing process according to the present embodiment is completed. FIG. 10 is a schematic diagram illustrating an example of a nuclear reactor including a drive shaft housing.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The components of each embodiment described below can be combined as appropriate. Some components may not be used.

[Hole processing equipment]
FIG. 1 is a diagram schematically showing a hole processing apparatus 1 according to the present embodiment. The hole processing apparatus 1 forms a hole in the workpiece W by a BTA (Boring and Trepanning Association) method. The BTA method is a process generated by cutting by supplying cutting oil to the tool (boring head) provided at the tip of the boring bar through the gap between the inner surface of the hole formed in the workpiece and the boring bar. This is a processing method that collects cutting chips of a product together with cutting oil through a boring bar. The BTA method is suitable for forming deep holes of 500 [mm] or more, for example.

  The hole processing device 1 is provided on the base member 2, the base member 2, the holding device 3 that holds the workpiece W, the support device 5 that is provided on the base member 2 and supports the boring bar 4, and the base member 2. Generated by cutting, a supply base 6 for supplying cutting oil to the gap between the inner surface of the hole formed in the workpiece W and the boring bar 4, a supply device 7 for supplying cutting oil to the supply base 6, and And a collection device 8 that collects the chips of the workpiece W together with the cutting oil through a boring bar.

  The holding device 3 includes a holding mechanism 3A that holds the workpiece W, and an actuator 3B that generates power for rotating the holding mechanism 3A. When the holding mechanism 3A rotates by the operation of the actuator 3B, the workpiece W held by the holding mechanism 3A rotates around the rotation axis AX.

  A tool (boring head) is provided at the tip of the boring bar 4. The boring bar 4 removably supports the tool. The tool can be exchanged for the boring bar 4. In the present embodiment, any one of the first tool 10, the second tool 20, and the third tool 30 is provided at the tip of the boring bar 4.

  The support device 5 supports the boring bar 4 so as to be movable in a direction parallel to the rotation axis AX. By the movement of the boring bar 4, the tool is inserted into the hole of the workpiece W and the tool is removed from the hole of the workpiece W.

  The supply device 7 includes a tank 7 </ b> A that stores cutting oil, a pipe 7 </ b> B that connects the tank 7 </ b> A and the supply base 6, and a pump 7 </ b> C that generates power for sending the cutting oil in the tank 7 </ b> A to the supply base 6. .

  The supply table 6 supports the boring bar 4 and the workpiece W. The cutting oil is supplied to the gap between the inner surface of the hole formed in the workpiece W and the boring bar 4 via the supply base 6. The cutting oil supplied to the gap is supplied to a tool provided at the tip of the boring bar 4. Processing with the tool is performed while cutting oil is supplied to the tool.

  The collection device 8 collects the chips of the workpiece W generated by cutting through the boring bar 4 together with the cutting oil. The boring bar 4 is a hollow pipe member. Chips and cutting oil are collected through the internal flow path of the boring bar 4. The recovery device 8 includes a separation device 8A that separates chips from the cutting oil that has flowed through the internal flow path of the boring bar 4, a circulation member 8B that returns the cutting oil that has passed through the separation device 8A to the tank 7A, and lubrication. And a magnet filter 8C for removing chips remaining in the oil.

[Drilling method]
Next, a hole machining method according to this embodiment will be described. FIG. 2 is a flowchart showing the hole machining method according to this embodiment. As shown in FIG. 2, in the hole machining method, the first tool 10 and the workpiece W are relatively rotated to form a hole including a straight portion in the workpiece W (step SP1). The second tool 20 inserted into the hole and the workpiece W are relatively rotated to roughly process the bottom of the hole (step SP2), and the third tool 30 inserted into the hole and the workpiece. And a finishing step (step SP3) in which W is relatively rotated to finish the bottom of the hole into a spherical shape.

(Step SP1: Hole forming step)
The hole forming process will be described. FIG. 3 is a view showing the first tool 10 used in the hole forming step. The first tool 10 includes a body (first body) 11, a blade (first blade) 12 fixed to the body 11, and a pad member (first pad member) 13 fixed to the body 11.

  The body 11 is made of metal. The body 11 is at least partially cylindrical and is disposed around a central axis (first central axis) J1.

  A plurality of blades 12 are provided at the tip of the body 11. At least a part of the blade 12 is arranged at a distance R12 from the central axis J1 of the body 11 with respect to the radial direction of the body 11 (radial direction with respect to the central axis J1). A part of the blade 12 disposed at the distance R <b> 12 is a part that protrudes outward from the outer surface of the body 11 in the radial direction of the body 11. In the following description, the distance R12 is appropriately referred to as the maximum radius R12 of the blade 12.

  The maximum radius R12 refers to the distance between the central axis J1 and the outermost portion (outermost diameter portion) of the blade 12 in the radial direction with respect to the central axis J1. When there are a plurality of blades 12, the outermost diameter portion of the blade 12 refers to the outermost portion of the plurality of blades 12 with respect to the radial direction with respect to the central axis J1.

  A plurality of pad members 13 are provided on the side surface of the body 11. In the present embodiment, the pad member (first pad member) 13 includes pad members 131, 132, 133, and 134 that are arranged at different positions with respect to a direction parallel to the central axis J1. The first tool 10 includes a first group G1 of pad members 13 including a plurality of pad members 131 arranged so as to surround the central axis J1, and a central axis at a position farther from the blade 12 than the first group G1. A second group G2 of pad members 13 composed of a plurality of pad members 132 arranged so as to surround J1 and a position away from the second group G2 with respect to the blade 12 are arranged so as to surround the central axis J1. A pad composed of a third group G3 of pad members 13 composed of a plurality of pad members 133 and a plurality of pad members 134 arranged so as to surround the central axis J1 at a position further away from the blade 12 than the third group G3. A fourth group G4 of members 13;

  Of the first group G1, the second group G2, the third group G3, and the fourth group G4, the pad member 131 of the first group G1 is provided on the most distal end side of the body 11 and is next to the first group G1. The second group G2 pad member 132 is provided on the distal end side of the body 11, the second group G2 is followed by the third group G3 pad member 133 on the distal end side of the body 11, and the fourth group G4 pad member is provided. 134 is provided on the most proximal end side of the body 11.

  A plurality of pad members 131 of the first group G1 are provided on the side surface of the body 11. Three pad members 131 are arranged around the central axis J1. Three pad members 131 and one blade 12 are arranged around the central axis J1.

  Similarly, three pad members 132 of the second group G2 are arranged around the central axis J1.

  Four pad members 133 of the third group G3 are arranged at equal intervals around the central axis J1.

  Four pad members 134 of the fourth group G4 are also arranged at equal intervals around the central axis J1.

  The pad member 131 of the first group G1 and the pad member 132 of the second group G2 are made of ceramics and are harder than the pad member 133 of the third group G3 and the pad member 134 of the fourth group G4. The pad member 131 of the first group G1 and the pad member 132 of the second group G2 may be made of cemented carbide.

  The pad member 131 of the first group G1 has a surface 131A that faces outward in the radial direction of the body 11. The pad member 131 is provided on the body 11 so that the distance from the central axis J1 of the body 11 to the surface 131A is a distance R131 in the radial direction of the body 11. In the following description, the distance R131 is appropriately referred to as the maximum radius R131 of the pad member 131.

  The pad member 132 of the second group G2 has a surface 132A that faces outward in the radial direction of the body 11. The pad member 132 is provided on the body 11 so that the distance from the central axis J1 of the body 11 to the surface 132A is a distance R132 in the radial direction of the body 11. In the following description, the distance R132 is appropriately referred to as the maximum radius R132 of the pad member 132.

  The pad member 133 of the third group G3 and the pad member 134 of the fourth group G4 are made of synthetic resin and are softer than the body 11 and the blade 12.

  The pad member 133 of the third group G3 has a surface 133A that faces outward in the radial direction of the body 11. The pad member 133 is provided on the body 11 such that the distance from the central axis J1 of the body 11 to the surface 133A is a distance R133 in the radial direction of the body 11. In the following description, the distance R133 is appropriately referred to as the maximum radius R133 of the pad member 133. In FIG. 3, the illustration of the maximum radius R133 is omitted.

  The pad member 134 of the fourth group G4 has a surface 134A that faces outward in the radial direction of the body 11. The pad member 134 is provided on the body 11 so that the distance from the central axis J1 of the body 11 to the surface 134A is a distance R134 in the radial direction of the body 11. In the following description, the distance R134 is appropriately referred to as the maximum radius R134 of the pad member 134.

  The maximum radius R131 refers to the distance between the central axis J1 and the outermost portion (outermost diameter portion) of the pad member 131 in the radial direction with respect to the central axis J1. When there are a plurality of pad members 131, the outermost diameter portion of the pad member 131 is the outermost portion of the plurality of pad members 131 with respect to the radial direction with respect to the central axis J1. The same applies to the maximum radii R132, R133, and R134.

  The maximum radius R12 of the blade 12 and the maximum radii R131 and R132 of the pad members 131 and 132 are equal. In the present embodiment, the maximum radius R12 of the blade 12 and the maximum radii R131, R132 of the pad members 131, 132 are set to a predetermined value (predetermined distance) R.

  The maximum radii R133 and R134 of the pad members 133 and 134 are desirably equal to or greater than the maximum radius R12 of the blade 12. In the present embodiment, the maximum radii R133 and R134 of the pad members 133 and 134 are the same as the maximum radius R12 of the blade 12, or a maximum of 0.01 [mm] (a maximum of 0.02 [mm] in diameter). . The pad members 133 and 134 are softer than the pad members 131 and 132, and are slightly deformed by coming into contact with the holes H as described later. Therefore, the pad members 133 and 134 and the inner surface of the hole H can be sufficiently brought into contact by making the maximum radii R133 and R134 slightly larger than the maximum radii R12, R131 and R132.

  When performing a hole formation process, the 1st tool 10 is provided in the front-end | tip part of the boring bar 4. As shown in FIG. With the tip of the first tool 10 and the end surface of the workpiece W held by the holding mechanism 3A facing each other, the workpiece W rotates around the rotation axis AX by the operation of the actuator 3B. The first tool 10 is provided on the boring bar 4 so that the central axis J1 coincides with the rotation axis AX. The support device 5 moves the boring bar 4 supporting the first tool 10 in a direction parallel to the rotation axis AX so that the first tool 10 is pushed into the workpiece W. When the workpiece W is rotating around the rotation axis AX, the first tool 10 moves in a direction parallel to the rotation axis AX, whereby a hole is formed in the workpiece W by the blade 12.

  The hole machining apparatus 1 moves the first tool 10 in a direction parallel to the rotation axis AX, pushes the first tool 10 into the workpiece W, and then pulls out the first tool 10 from the hole formed in the workpiece W. The support device 5 moves the boring bar 4 supporting the first tool 10 in a direction parallel to the rotation axis AX so that the first tool 10 is pulled out from the hole formed in the workpiece W.

  FIG. 4 is a cross-sectional view showing the workpiece W after the hole forming step. As shown in FIG. 4, the straight portion Hs having a diameter D corresponding to the maximum radius R <b> 12 (predetermined distance R) of the blade 12 is formed by a hole forming process including relative rotation between the first tool 10 and the workpiece W. A hole H to be included is formed in the workpiece W.

  As described above, in the present embodiment, the maximum radius R12 of the blade 12 and the maximum radii R131 and R132 of the pad members 131 and 132 are equal. Therefore, when the hole H is formed by the blade 12 while pushing the first tool 10 into the workpiece W, the surfaces 131A and 132A of the pad members 131 and 132 and the inner surface of the straight portion Hs of the hole H come into contact with each other. When the pad members 131 and 132 having the same distance from the central axis J1 as the blade 12 are in contact with the inner surface of the straight portion Hs, the body 11 is supported on the inner surface of the straight portion Hs via the pad members 131 and 132. Become. Further, the maximum radii R133 and R134 of the pad members 133 and 134 that are softer than the pad members 131 and 132 are the same as or slightly larger than the maximum radii R131 and R132. When the maximum radii R133 and R134 are slightly larger than the maximum radii R131 and R132, the pad members 133 and 134 are slightly deformed by contacting the holes H. Therefore, the synthetic resin pad members 133 and 134, which are softer than the pad members 131 and 132, also sufficiently contact the inner surface of the straight portion Hs. Therefore, it is possible to suppress the body 11 from being bent or shaken in the hole formation by the blade 12. Therefore, the straight portion Hs of the hole H is formed with high processing accuracy.

  Further, when the first tool 10 is pulled out from the hole H after the hole formation by the blade 12 is finished, the surfaces 131A and 132A of the pad members 131 and 132 having the same distance from the central axis J1 as the outermost diameter portion of the blade 12 are formed. It is in contact with the inner surface of the straight portion Hs. Also, the synthetic resin pad members 133 and 134, which are softer than the pad members 131 and 132 and have the maximum radius R133, R134 equal to or slightly larger than the maximum radius R131, R132, are also sufficient on the inner surface of the straight portion Hs. Contact. Therefore, the first tool 10 can be pulled out while suppressing the bending or deflection of the body 11. Therefore, the blade 12 is suppressed from biting into the inner surface of the straight portion Hs, and damage to the inner surface of the straight portion Hs is suppressed.

(Step SP2: Roughing process)
Next, the roughing process will be described. The roughing process is performed after the hole forming process. FIG. 5 is a diagram showing the second tool 20 used in the roughing process. The second tool 20 includes a body (second body) 21, a blade (second blade) 22 fixed to the body 21, and a pad member (second pad member) 23 fixed to the body 21.

  The body 21 is made of metal. The body 21 is at least partially cylindrical and is disposed around a central axis (second central axis) J2.

  A plurality of blades 22 are provided at the tip of the body 21. At least a part of the blade 22 is disposed at a distance R22 from the central axis J2 of the body 21 with respect to the radial direction of the body 21 (radial direction with respect to the central axis J2). A part of the blade 22 disposed at the distance R <b> 22 is a portion that protrudes outward from the outer surface of the body 21 in the radial direction of the body 21. In the following description, the distance R22 is appropriately referred to as the maximum radius R22 of the blade 22.

  The maximum radius R22 refers to the distance between the central axis J2 and the outermost portion (outermost diameter portion) of the blade 22 in the radial direction with respect to the central axis J2. When there are a plurality of blades 22, the outermost diameter portion of the blade 22 refers to the outermost portion of the plurality of blades 22 in the radial direction with respect to the central axis J <b> 2.

  A plurality of pad members 23 are provided on the side surface of the body 21. In the present embodiment, the pad member (second pad member) 23 includes pad members 231, 232, and 233 that are arranged at different positions with respect to a direction parallel to the central axis J2. The second tool 20 includes a fifth group G5 of pad members 23 including a plurality of pad members 231 arranged so as to surround the central axis J2, and a central axis at a position away from the fifth group G5 with respect to the blade 22. A sixth group G6 of pad members 23 composed of a plurality of pad members 232 arranged so as to surround J2, and a position away from the sixth group G6 with respect to the blade 22 so as to surround the central axis J2. A seventh group G7 of pad members 23 composed of a plurality of pad members 233.

  Of the fifth group G5, the sixth group G6, and the seventh group G7, the pad member 231 of the fifth group G5 is provided on the most distal end side of the body 21, and the pad of the sixth group G6 is next to the fifth group G5. The member 232 is provided on the distal end side of the body 21, and the pad member 233 of the seventh group G 7 is provided on the most proximal end side of the body 11.

  A plurality of pad members 231 of the fifth group G5 are provided on the side surface of the body 21. Three pad members 231 are arranged around the central axis J2. Three pad members 231 and one blade 22 are arranged around the central axis J2.

  Similarly, three pad members 232 of the sixth group G6 are arranged around the central axis J2.

  Four pad members 333 of the seventh group G7 are arranged at equal intervals around the central axis J2.

  The pad member 231 of the fifth group G5 and the pad member 232 of the sixth group G6 are made of ceramics and are harder than the pad member 233 of the seventh group G7. The pad member 231 of the fifth group G5 and the pad member 232 of the sixth group G6 may be made of cemented carbide.

  The pad member 231 of the fifth group G5 has a surface 231A that faces outward in the radial direction of the body 21. The pad member 231 is provided on the body 21 so that the distance from the central axis J2 of the body 21 to the surface 231A is a distance R231 in the radial direction of the body 21. In the following description, the distance R231 is appropriately referred to as the maximum radius R231 of the pad member 231.

  The pad member 232 of the sixth group G6 has a surface 232A that faces outward in the radial direction of the body 21. The pad member 232 is provided on the body 21 so that the distance from the central axis J2 of the body 21 to the surface 232A is a distance R232 in the radial direction of the body 21. In the following description, the distance R232 is appropriately referred to as the maximum radius R232 of the pad member 232.

  The pad member 233 of the seventh group G7 is made of synthetic resin and is softer than the body 21 and the blade 22.

  The pad member 233 of the seventh group G7 has a surface 233A that faces outward in the radial direction of the body 21. The pad member 233 is provided on the body 21 such that the distance from the central axis J2 of the body 21 to the surface 233A is a distance R233 with respect to the radial direction of the body 21. In the following description, the distance R233 is appropriately referred to as the maximum radius R233 of the pad member 233.

  The maximum radius R231 refers to the distance between the central axis J2 and the outermost portion (outermost diameter portion) of the pad member 231 in the radial direction with respect to the central axis J2. When there are a plurality of pad members 231, the outermost diameter portion of the pad member 231 is the outermost portion of the plurality of pad members 231 in the radial direction with respect to the central axis J <b> 2. The same applies to the maximum radii R232 and R233.

  The maximum radius R22 of the blade 22 and the maximum radii R231 and R232 of the pad members 231 and 232 are equal. In the present embodiment, the maximum radius R22 of the blade 22 and the maximum radii R231 and R232 of the pad members 231 and 232 are set to a predetermined value (predetermined distance) R.

  That is, in this embodiment, the maximum radius R12 of the blade 12 of the first tool 10, the maximum radii R131 and R132 of the pad members 131 and 132 of the first tool 10, and the maximum radius R22 of the blade 22 of the second tool 20 The maximum radii R231 and R232 of the pad members 231 and 232 of the second tool 20 are equal.

  The maximum radius R233 of the pad member 233 is desirably equal to or greater than the maximum radius R22 of the blade 22. In the present embodiment, the maximum radius R233 of the pad member 233 is the same as the maximum radius R22 of the blade 22, or a maximum of 0.01 [mm] (a maximum of 0.02 [mm] in diameter). The pad member 233 is softer than the pad members 231 and 232 and is slightly deformed by contacting the hole H as described later. Therefore, the pad member 233 and the inner surface of the hole H can be sufficiently brought into contact with each other by making the maximum radius R233 slightly larger than the maximum radii R22, R231, R232.

  In the present embodiment, the maximum radii R13 and R134 of the pad members 133 and 134 of the first tool 10 and the maximum radius R233 of the pad member 233 of the second tool 20 are equal.

  Further, as shown in FIG. 5, the blade 22 has a plurality of linear portions in a cross section including the central axis J <b> 2. The straight portion of the blade 22 is adjacent to the first straight portion 22A and the first straight portion 22A that are inclined with respect to the central axis J2 from one side of the central axis J2 to the other side in the radial direction of the body 21, and the body 21 includes a second straight portion 22B, a third straight portion 22C, and a fourth straight portion 22D that are inclined outward toward the rear end side of the body 21 with respect to the radial direction of 21. The first straight portion 22A is provided so as to intersect the central axis J2, and is inclined in a direction different from the second straight portion 22B. The corner portion of the boundary between the first straight portion 22A and the second straight portion 22B is disposed on the most distal end side of the second tool 20. The third straight portion 22C is disposed outside the second straight portion 22B with respect to the radial direction of the body 21. A step portion is provided at the boundary between the second straight portion 22B and the third straight portion 22C. The fourth straight part 22 </ b> D is disposed outside the third straight part 22 </ b> C with respect to the radial direction of the body 21. A corner is provided at the boundary between the third straight portion 22C and the fourth straight portion 22D.

  When executing the roughing process, the second tool 20 is provided at the tip of the boring bar 4. The second tool 20 is provided on the boring bar 4 so that the center axis J2 coincides with the rotation axis AX of the workpiece W. The support device 5 supports the second tool 20 in a direction parallel to the rotation axis AX so that the second tool 20 is inserted into the hole H formed in the workpiece W in the hole forming step (step SP1). The boring bar 4 is moved. The support device 5 moves the boring bar 4 until the blade 22 of the second tool 20 reaches the bottom Hb of the hole H. In a state where the blade 22 of the second tool 20 is arranged at the bottom of the hole H, the workpiece W rotates about the rotation axis AX, whereby the bottom portion Hb of the hole H of the workpiece W is roughly processed by the blade 22. The

  The hole machining apparatus 1 performs rough machining on the bottom Hb of the hole H with the blade 22 of the second tool 20, and then pulls out the second tool 20 from the hole H of the workpiece W. The support device 5 moves the boring bar 4 supporting the second tool 20 in a direction parallel to the rotation axis AX so that the second tool 20 is pulled out from the hole H of the workpiece W.

  FIG. 6 is a cross-sectional view showing the workpiece W after the roughing process is completed. As shown in FIG. 6, a hole H having a bottom Hb corresponding to the shape of the blade 22 is formed in the workpiece W by a roughing process including a relative rotation between the second tool 20 and the workpiece W.

  The maximum radius R12 of the blade 12 and the maximum radius R22 of the blade 22 are equal. In the roughing process (step SP2), the straight part Hs formed in the hole forming process (step SP1) is not processed, and only the bottom part Hb is processed. In the first tool 10 and the second tool 20, the distance from the central axis J1 (rotation axis AX) to the outermost diameter part of the blade 12 and the distance from the central axis J2 (rotation axis AX) to the outermost diameter part of the blade 22 Therefore, the formation of a step at the boundary between the inner surface of the straight portion Hs formed in the hole forming step (step SP1) and the inner surface of the bottom portion Hb processed in the roughing step (step SP2) is suppressed. The inner surface of the straight portion Hs and the inner surface of the bottom portion Hb are smoothly connected. Further, since the distance from the rotation axis AX to the outermost diameter portion of the blade 12 is equal to the distance from the rotation axis AX to the outermost diameter portion of the blade 22, the blade 22 contacts the inner surface of the hole H in the roughing process. Therefore, it is possible to suppress the body 22 from being bent or shaken. Therefore, the bottom Hb of the hole H is processed stably.

  In the cross section including the central axis J2, the blade 22 has a plurality of linear portions 22A, 22B, 22C, and 22D. By forming the blade 22 with a plurality of straight portions, the occurrence of self-excited vibration (chatter) is suppressed, and rough machining can be executed at high speed.

  In the present embodiment, the maximum radius R22 of the blade 22 and the maximum radii R231 and R232 of the pad members 231 and 232 are equal. Therefore, in the roughing process, the bottom 22b of the hole H is roughly processed by the blade 22 of the second tool 20 in a state where the surfaces 231A and 232A of the pad members 231 and 232 are in contact with the inner surface of the straight part Hs of the hole H. The When the surfaces 231A and 232A of the pad members 231 and 232 having the same distance from the central axis J2 as the outermost diameter portion of the blade 22 are in contact with the inner surface of the straight portion Hs, the body 21 is straight through the pad members 231 and 232. It will be supported by the inner surface of the portion Hs. The maximum radius R233 of the pad member 233 that is softer than the pad members 231 and 232 is the same as or slightly larger than the maximum radii R231 and R232. When the maximum radius R233 is slightly larger than the maximum radii R231 and R232, the pad member 233 is slightly deformed by contacting the hole H. Therefore, the synthetic resin pad member 233 which is softer than the pad members 231 and 232 sufficiently contacts the inner surface of the straight portion Hs. For this reason, the body 21 is restrained from being bent or shaken during rough machining by the blade 22. Therefore, rough processing of the bottom Hb of the hole H is stably performed.

  When the second tool 20 is pulled out from the hole H after the rough machining by the blade 22 is finished, the surface 233A of the pad member 233 whose distance from the center axis J2 is equal to the outermost diameter portion of the blade 22 is the straight portion Hs. It is in contact with the inner surface. Further, a pad member 233 made of a synthetic resin, which is softer than the pad members 231 and 232 and has a maximum radius R233 equal to or slightly larger than the maximum radii R231 and R232, also sufficiently contacts the inner surface of the straight portion Hs. Therefore, the second tool 20 can be pulled out while suppressing the bending or deflection of the body 21. Therefore, it is suppressed that the blade 22 bites into the inner surface of the straight portion Hs, and damage to the inner surface of the straight portion Hs is suppressed.

(Step SP3: Finishing process)
Next, the finishing process will be described. The finishing process is performed after the roughing process. FIG. 7 is a diagram showing the third tool 30 used in the finishing process. The third tool 30 includes a body (third body) 31, a blade (third blade) 32 fixed to the body 31, and a pad member (third pad member) 33 fixed to the body 31.

  The body 31 is made of metal. The body 31 is at least partially cylindrical and is disposed around a central axis (third central axis) J3.

  The blade 32 is provided at the tip of the body 31. At least a part of the blade 32 is disposed at a distance R32 from the central axis J3 of the body 31 with respect to the radial direction of the body 31 (radial direction with respect to the central axis J3). A part of the blade 32 disposed at the distance R <b> 32 is a portion that protrudes outward from the outer surface of the body 31 in the radial direction of the body 31. In the following description, the distance R32 is appropriately referred to as the maximum radius R32 of the blade 32.

  The maximum radius R32 refers to the distance between the central axis J3 and the outermost portion (outermost diameter portion) of the blade 32 in the radial direction with respect to the central axis J3. When there are a plurality of blades 32, the outermost diameter portion of the blade 32 refers to the outermost portion of the plurality of blades 32 with respect to the radial direction with respect to the central axis J3.

  A plurality of pad members 33 are provided on the side surface of the body 31. In the present embodiment, the pad member (third pad member) 33 includes pad members 331 and 332 arranged at different positions with respect to the direction parallel to the central axis J3. The third tool 30 has a central axis at a position farther from the eighth group G8 than the eighth group G8 of the pad member 33 including a plurality of pad members 331 disposed so as to surround the central axis J3 and the blade 32. 9th group G9 of pad members 33 which consist of a plurality of pad members 332 arranged so that J3 may be surrounded.

  Of the eighth group G8 and the ninth group G9, the pad member 331 of the eighth group G8 is provided on the most distal end side of the body 31, and the pad member 332 of the ninth group G9 is disposed on the most proximal end side of the body 31. Provided.

  A plurality of pad members 331 of the eighth group G8 are provided on the side surface of the body 31. Three pad members 331 are arranged around the central axis J3. Three pad members 331 and one blade 32 are arranged around the central axis J3.

  Four pad members 332 of the ninth group G9 are arranged at equal intervals around the central axis J3.

  The pad member 331 of the eighth group G8 is made of ceramics and is harder than the pad member 232 of the ninth group G9. The pad member 331 of the eighth group G8 may be made of cemented carbide.

  The pad member 331 of the eighth group G8 has a surface 331A that faces outward in the radial direction of the body 31. The pad member 331 is provided on the body 31 such that the distance from the central axis J3 of the body 31 to the surface 331A is a distance R331 with respect to the radial direction of the body 31. In the following description, the distance R331 is appropriately referred to as the maximum radius R331 of the pad member 331.

  The pad member 332 of the ninth group G9 is made of synthetic resin and is softer than the body 31 and the blade 32.

  The pad member 332 of the ninth group G9 has a surface 332A that faces outward in the radial direction of the body 31. The pad member 332 is provided on the body 31 such that the distance from the central axis J3 of the body 31 to the surface 332A is a distance R332 in the radial direction of the body 31. In the following description, the distance R332 is appropriately referred to as the maximum radius R332 of the pad member 332.

  The maximum radius R331 refers to the distance between the central axis J3 and the outermost portion (outermost diameter portion) of the pad member 331 in the radial direction with respect to the central axis J3. When there are a plurality of pad members 331, the outermost diameter portion of the pad member 331 refers to the outermost portion of the plurality of pad members 331 in the radial direction with respect to the central axis J3. The same applies to the maximum radius R332.

  The maximum radius R32 of the blade 32 and the maximum radius R331 of the pad member 331 are equal. In the present embodiment, the maximum radius R32 of the blade 32 and the maximum radius R331 of the pad member 331 are set to a predetermined value (predetermined distance) R.

  That is, in this embodiment, the maximum radius R12 of the blade 12 of the first tool 10, the maximum radii R131 and R132 of the pad members 131 and 132 of the first tool 10, and the maximum radius R22 of the blade 22 of the second tool 20 The maximum radii R231 and R232 of the pad members 231 and 232 of the second tool 20, the maximum radius R32 of the blade 32 of the third tool 30, and the maximum radius R331 of the pad member 331 of the third tool 30 are equal.

  The maximum radius R332 of the pad member 332 is desirably equal to or greater than the maximum radius R32 of the blade 32. In the present embodiment, the maximum radius R332 of the pad member 332 is the same as or larger than the maximum radius R32 of the blade 32 by 0.01 [mm] (maximum 0.02 [mm] in diameter). The pad member 332 is softer than the pad member 331 and is slightly deformed by coming into contact with the hole H as will be described later. Therefore, the pad member 332 and the inner surface of the hole H can be sufficiently brought into contact with each other by making the maximum radius R332 slightly larger than the maximum radii R32 and R331.

  Further, in the present embodiment, the maximum radius R133, R134 of the pad member 133, 134 of the first tool 10, the maximum radius R233 of the pad member 233 of the second tool 20, and the maximum radius of the pad member 332 of the third tool 30. R332 is equal.

  Further, as shown in FIG. 7, in the cross section including the central axis J3, the blade 32 has an arc portion 32A and a straight portion 32B.

  FIG. 8 is an enlarged view of a part of the blade 32. The straight portion 32B of the blade 32 is provided so as to be inclined from the central axis J3 toward the outer side with respect to the central axis J3 with respect to the radial direction of the body 31. The linear portion 32B is inclined outward toward the rear end portion of the body 31 with respect to the radial direction with respect to the central axis J3. The straight line portion 32B is provided so as to connect the point C1 and the point C2 disposed outside the point C1 with respect to the central axis J3. Point C1 is on central axis J3. At least a part of the arc portion 32A of the blade 32 is disposed on the central axis J3.

  At least a part of the arc portion 32A is disposed on the central axis J3. The arc portion 32A is connected to the straight portion 32B outside the central axis J3. Note that the boundary between the arc portion 32A and the straight portion 32B may be positioned on the central axis J3. A portion having a maximum radius R32 is provided in the arc portion 32A.

  When executing the finishing process, the third tool 30 is provided at the tip of the boring bar 4. The third tool 30 is provided on the boring bar 4 so that the central axis J3 coincides with the rotation axis AX of the workpiece W. The support device 5 supports the third tool 30 in a direction parallel to the rotation axis AX so that the third tool 30 is inserted into the hole H of the workpiece W processed in the roughing process (step SP2). The boring bar 4 is moved. The support device 5 moves the boring bar 4 until the blade 32 of the third tool 30 reaches the bottom Hb of the hole H. In a state where the blade 32 of the third tool 30 is disposed at the bottom Hb of the hole H, the workpiece W rotates about the rotation axis AX, so that the blade 32 causes the inner surface of the bottom Hb of the hole H of the workpiece W to rotate. The bottom Hb is finished so as to be spherical.

  The hole processing apparatus 1 finishes the bottom Hb of the hole H with the blade 32 of the third tool 30 and then extracts the third tool 30 from the hole H of the workpiece W. The support device 5 moves the boring bar 4 supporting the third tool 30 in a direction parallel to the rotation axis AX so that the third tool 30 is pulled out from the hole H of the workpiece W.

  FIG. 9 is a cross-sectional view showing the workpiece W after the finishing process is completed. Through the finishing process including the relative rotation of the third tool 30 and the workpiece W, a hole H having a spherical bottom Hb corresponding to the shape of the blade 32 is formed in the workpiece W as shown in FIG. The

  The maximum radius R12 of the blade 12 and the maximum radius R32 of the blade 32 are equal. In the finishing process (step SP3), the straight part Hs formed in the hole forming process (step SP1) is not processed, and only the bottom part Hb is processed. In the first tool 10 and the third tool 30, since the distance of the blade 12 from the central axis J1 (rotational axis AX) and the blade 32 from the central axis J3 (rotational axis AX) are equal, the hole forming step (step SP1) It is suppressed that a step is formed at the boundary between the inner surface of the straight portion Hs formed in step S3 and the inner surface of the bottom portion Hb processed in the finishing step (step SP3), and the inner surface of the straight portion Hs and the inner surface of the bottom portion Hb Are connected smoothly. Further, since the distance from the rotation axis AX to the blade 12 is equal to the distance from the rotation axis AX to the blade 32, the blade 32 can continue to be in contact with the inner surface of the hole H in the finishing process. Spilling and shaking are suppressed. Therefore, the bottom Hb of the hole H is formed with high processing accuracy.

  In the cross section including the central axis J3, the blade 32 has an arc portion 32A. A bottom portion Hb having a spherical inner surface is formed by the arc portion 32A.

  Moreover, the part which cross | intersects the center axis | shaft J3 among the bottom parts Hb is a part with a low relative rotational speed with the 3rd tool 30, and being hard to process. For this reason, when the bottom Hb is processed, there is a possibility that a protrusion remains on the inner surface of the bottom Hb. In the present embodiment, since at least a part of the arc portion 32A, which is the arcuate blade 32, is disposed on the central axis J3, the remaining protrusions are suppressed. In the present embodiment, since the shape, size, angle, and the like of the arc portion 32A and the straight portion (relief portion) 32B are optimized, the remaining protrusions are suppressed, and the inner surface of the bottom portion Hb is finished in a spherical shape. be able to.

  In the present embodiment, the maximum radius R32 of the blade 32 and the maximum radius R331 of the pad member 331 are equal. Therefore, in the finishing process, the bottom portion Hb of the hole H is finished with the blade 32 of the third tool 30 in a state where the surface 331A of the pad member 331 and the inner surface of the straight portion Hs of the hole H are in contact with each other. When the pad member 331 having the same diameter as the blade 32 contacts the inner surface of the straight portion Hs, the body 31 is supported on the inner surface of the straight portion Hs via the pad member 331. Further, the maximum radius R332 of the pad member 332 that is softer than the pad member 331 is the same as or slightly larger than the maximum radius R331. When the maximum radius R 332 is slightly larger than the maximum radius R 331, the pad member 332 is slightly deformed by contacting the hole H. Therefore, the synthetic resin pad member 332, which is softer than the pad member 331, also sufficiently contacts the inner surface of the straight portion Hs. Therefore, it is possible to suppress the body 31 from being bent or shaken during rough machining by the blade 32. Therefore, finishing of the bottom Hb of the hole H is performed with high processing accuracy.

  When the third tool 30 is pulled out from the hole H after finishing with the blade 32, the surface 331A of the pad member 331 whose distance from the center axis J3 is equal to the outermost diameter portion of the blade 32 is the straight portion Hs. It is in contact with the inner surface. Further, a synthetic resin pad member 332 that is softer than the pad member 331 and has a maximum radius R332 equal to or slightly larger than the maximum radius R331 also sufficiently contacts the inner surface of the straight portion Hs. Therefore, the third tool 30 can be pulled out while suppressing the bending or deflection of the body 31. Therefore, the blade 32 is prevented from biting into the inner surface of the straight portion Hs, and damage to the inner surface of the straight portion Hs is suppressed.

  As described above, according to the present embodiment, it is possible to provide a hole drilling method in which the formation of steps, protrusions, and uneven portions is suppressed. Further, by using a plurality of tools 10, 20, and 30, the burden on each tool 10, 20, and 30 can be reduced, and the life of the tools 10, 20, and 30 can be extended.

  In the present embodiment, the hole H is processed by rotating the workpiece W with respect to the tools 10, 20, and 30. The tools 10, 20, 30 may rotate, or both the tools 10, 20, 30 and the workpiece W may rotate.

[Example of application of workpiece]
The hole processing method according to the present embodiment is suitable for processing a deep hole in which the length T of the straight portion Hs is 500 [mm] or more. The workpiece W that has been finished and provided with the hole H including the straight portion Hs and the spherical bottom portion Hb can be used, for example, in a drive shaft housing of a nuclear reactor. Hereinafter, an example of the nuclear reactor according to the present embodiment will be described.

  FIG. 10 is a schematic diagram illustrating an example of the nuclear reactor 100. A nuclear reactor 100 shown in FIG. 1 is a pressurized water reactor (PWR). In the reactor 100 according to the present embodiment, a reactor vessel 101 provided as a pressure vessel is mounted on the reactor vessel body 102 and the upper portion of the reactor vessel body 102 and can be opened and closed with respect to the reactor vessel body 102. And a reactor vessel lid 103. The reactor vessel main body 102 is formed with an inlet nozzle 104 and an outlet nozzle 105 for supplying and discharging light water as primary cooling water that is cooling water used in the primary cooling system.

  Below the inlet nozzle 104 and the outlet nozzle 105, a core tank 110 formed in a substantially cylindrical shape is provided. The upper part of the core tank 110 is connected to the upper core plate 111. The lower part of the core tank 110 is connected to the lower core plate 112.

  An upper core support plate 113 is fixed above the core tank 110. The upper core support plate 113 is provided by suspending a plurality of core support rods 114, and the upper core plate 111 is suspended and supported via the core support rods 114. The lower core plate 112 is positioned and held by a plurality of radial keys 115 with respect to the inner surface of the reactor vessel main body 102.

  The core 120 includes a core tank 110, an upper core plate 111, and a lower core plate 112. A large number of fuel assemblies 121 are arranged in the core 120. The fuel assembly 121 is configured such that a control rod 122 can be inserted. A plurality of upper ends of the control rod 122 are combined into a control rod cluster 123. The upper core plate 111 is supported by a number of control rod cluster guide tubes 124 that penetrate the upper core support plate 113. The control rod cluster guide tube 124 guides the control rod cluster 123. A control rod drive shaft 140 extending from the control rod drive device 125 is connected to the control rod cluster 123 through the control rod cluster guide tube 124 and extends to the fuel assembly 121.

  A portion communicating with the outlet nozzle 105 is formed as an upper plenum 130A. A hemispherical space formed by the lower core plate 112 and the inner surface of the spherically closed portion at the bottom of the reactor vessel main body 102 is formed as a lower plenum 130B. A portion communicating with the inlet nozzle 104 and the lower plenum 130B is formed as a downcomer portion 130C.

  When fission reaction is performed on the fissile material, the amount of control rod 122 inserted into the fuel assembly 121 is adjusted by a control rod driving device 125 provided in the reactor vessel lid 103. Thereby, the fission reaction in the core 120 is controlled.

  The control rod driving device 125 is provided in the nuclear reactor 100. The control rod drive device 125 moves the control rod drive shaft 140. The control rod drive device 125 moves the control rod drive shaft 140 in a direction (vertical direction) parallel to the central axis of the control rod drive shaft 140. As the control rod drive shaft 140 moves in the vertical direction, the control rod 122 connected to the control rod drive shaft 140 via the control rod cluster 123 moves in the vertical direction.

  The control rod drive device 125 includes a drive shaft housing 160, a drive shaft guide tube 161 that guides the control rod drive shaft 140, a latch mechanism that can move while holding the control rod drive shaft 140 intermittently, and a control rod drive. And a drive mechanism that moves the shaft 140 in the vertical direction.

  The drive shaft housing 160 includes a latch housing 162 that houses a latch mechanism and a cap 163 that closes the upper end of the drive shaft guide tube 161. The latch housing 162 is disposed so as to surround a part of the outer periphery of the drive shaft guide tube 161. Yes.

  The lower end of the latch housing 162 is connected to a cylindrical nozzle 164 that is welded through the reactor vessel lid 103. The drive shaft guide tube 161 is inserted from the upper end of the latch housing 162 and connected to the latch housing 162. Then, assuming that the control rod drive shaft 140 has failed, in order to take out the control rod drive shaft 140, the nozzle 164 and the latch housing 162, the latch housing 162 and the drive shaft guide tube 161, the drive shaft guide tube 161 and the cap 163 are taken out. Are detachably connected to each other by screw connection.

  The workpiece W machined by the hole machining method according to the present embodiment can be applied to the drive shaft housing 160. Since the formation of the step and the uneven portion is suppressed and the spherical bottom Hb is formed with high surface accuracy, the stress concentration on the inner surface of the hole H is suppressed. Therefore, the high-quality workpiece W (drive shaft housing 160) and the nuclear reactor 100 can be provided.

DESCRIPTION OF SYMBOLS 1 Hole processing apparatus 2 Base member 3 Holding apparatus 3A Holding mechanism 3B Actuator 4 Boring bar 5 Support apparatus 6 Supply stand 7 Supply apparatus 7A Tank 7B Pipe 7C Pump 8 Collection | recovery apparatus 8A Separation apparatus 8B Circulation member 8C Magnet filter 10 1st tool 11 Body (first body)
12 blades (first blade)
13 Pad member (first pad member)
20 Second tool 21 Body (second body)
22 blades (second blade)
22A 1st linear part 22B 2nd linear part 22C 3rd linear part 22D 4th linear part 23 Pad member (2nd pad member)
30 Third tool 31 Body (third body)
32 blades (3rd blade)
32A Arc portion 32B Straight portion 33 Pad member (third pad member)
DESCRIPTION OF SYMBOLS 100 Reactor 101 Reactor vessel 102 Reactor vessel body 103 Reactor vessel lid 104 Inlet nozzle 105 Outlet nozzle 110 Core tank 111 Upper core plate 112 Lower core plate 113 Upper core support plate 114 Core support rod 115 Radial key 120 Core 121 Fuel Assembly 122 Control rod 123 Control rod cluster 124 Control rod cluster guide tube 125 Control rod drive device 130A Upper plenum 130B Lower plenum 130C Downcommer 131 131 Pad member (first pad member)
132 Pad member (first pad member)
133 Pad member (first pad member)
134 Pad member (first pad member)
140 Control rod drive shaft 160 Drive shaft housing 161 Drive shaft guide tube 162 Latch housing 163 Cap 231 Pad member (second pad member)
232 Pad member (second pad member)
331 Pad member (third pad member)
332 Pad member (third pad member)
AX Rotation axis C1 Point C2 Point D Diameter G1 First group G2 Second group H Hole Hs Straight part Hb Bottom radius R12 Maximum radius R13 Maximum radius R22 Maximum radius R23 Maximum radius R32 Maximum radius R33 Maximum radius J1 Central axis (first central axis )
J2 central axis (second central axis)
J3 central axis (third central axis)
T Length W Workpiece

Claims (6)

A first tool having a first blade fixed to the first body and the first body and having a first blade disposed at a predetermined distance from the first central axis of the first body with respect to the radial direction is relatively moved with respect to the workpiece. A hole forming step of rotating and forming a hole including a straight portion having a diameter corresponding to the predetermined distance in the workpiece;
A second tool having a second blade fixed to the second body and the second body and having a second blade disposed at the predetermined distance from the second central axis of the second body with respect to a radial direction; , A rough machining step of relatively rotating the second tool and the workpiece to rough the bottom of the hole;
A third tool having a third blade fixed to the third body and the third body and having a third blade disposed at the predetermined distance from the third central axis of the third body with respect to the radial direction; A finishing step of relatively rotating the third tool and the workpiece to finish the bottom portion into a spherical shape;
Only including,
In the cross section including the second central axis, the second blade has a plurality of straight portions.
Drilling method. A first tool having a first blade fixed to the first body and the first body and having at least a portion disposed at a predetermined distance from the first central axis of the first body with respect to the radial direction is relatively moved with the workpiece. A hole forming step of rotating and forming a hole including a straight portion having a diameter corresponding to the predetermined distance in the workpiece;
A second tool having a second blade fixed to the second body and the second body and having at least a portion disposed at the predetermined distance from the second central axis of the second body in the radial direction; , A rough machining step of relatively rotating the second tool and the workpiece to rough the bottom of the hole;
A third tool fixed to the third body and the third body and having a third tool at least partially disposed at the predetermined distance from the third central axis of the third body in the radial direction; A finishing step of relatively rotating the third tool and the workpiece to finish the bottom part into a spherical shape;
Only including,
In the cross section including the third central axis, the third blade has an arc portion and a straight portion,
At least a portion of the arc portion of the third blade is disposed on the third central axis;
The linear portion of the third blade is provided so as to be inclined with respect to the third central axis from the third central axis toward the outside with respect to the radial direction.
Drilling method. A first tool having a first blade fixed to the first body and the first body and having a first blade disposed at a predetermined distance from the first central axis of the first body with respect to the radial direction is relatively moved with respect to the workpiece. A hole forming step of rotating and forming a hole including a straight portion having a diameter corresponding to the predetermined distance in the workpiece;
A second tool having a second blade fixed to the second body and the second body and having a second blade disposed at the predetermined distance from the second central axis of the second body with respect to a radial direction; , A rough machining step of relatively rotating the second tool and the workpiece to rough the bottom of the hole;
A third tool having a third blade fixed to the third body and the third body and having a third blade disposed at the predetermined distance from the third central axis of the third body with respect to the radial direction; A finishing step of relatively rotating the third tool and the workpiece to finish the bottom portion into a spherical shape;
Only including,
The first tool includes a first pad member having a surface disposed at the predetermined distance from the first central axis with respect to a radial direction,
In at least a part of the hole forming step, the surface of the first pad member and the inner surface of the straight portion are in contact with each other.
Drilling method. A first tool having a first blade fixed to the first body and the first body and having a first blade disposed at a predetermined distance from the first central axis of the first body with respect to the radial direction is relatively moved with respect to the workpiece. A hole forming step of rotating and forming a hole including a straight portion having a diameter corresponding to the predetermined distance in the workpiece;
A second tool having a second blade fixed to the second body and the second body and having a second blade disposed at the predetermined distance from the second central axis of the second body with respect to a radial direction; , A rough machining step of relatively rotating the second tool and the workpiece to rough the bottom of the hole;
A third tool having a third blade fixed to the third body and the third body and having a third blade disposed at the predetermined distance from the third central axis of the third body with respect to the radial direction; A finishing step of relatively rotating the third tool and the workpiece to finish the bottom portion into a spherical shape;
Only including,
The second tool includes a second pad member having a surface disposed at the predetermined distance from the second central axis with respect to a radial direction,
In the roughing step, in a state where the surface of the second pad member and the inner surface of the straight portion are in contact with each other, the bottom portion is roughly processed with the second blade.
Drilling method. A first tool having a first blade fixed to the first body and the first body and having a first blade disposed at a predetermined distance from the first central axis of the first body with respect to the radial direction is relatively moved with respect to the workpiece. A hole forming step of rotating and forming a hole including a straight portion having a diameter corresponding to the predetermined distance in the workpiece;
A second tool having a second blade fixed to the second body and the second body and having a second blade disposed at the predetermined distance from the second central axis of the second body with respect to a radial direction; , A rough machining step of relatively rotating the second tool and the workpiece to rough the bottom of the hole;
A third tool having a third blade fixed to the third body and the third body and having a third blade disposed at the predetermined distance from the third central axis of the third body with respect to the radial direction; A finishing step of relatively rotating the third tool and the workpiece to finish the bottom portion into a spherical shape;
Only including,
The third tool includes a third pad member having a surface disposed at the predetermined distance from the third central axis with respect to a radial direction,
In the finishing step, the bottom portion is finished with the third blade in a state where the surface of the third pad member and the inner surface of the straight portion are in contact with each other.
Drilling method. The hole is a deep hole in which the straight portion is 500 [mm] or more,
The finished workpiece is used for a drive shaft housing of a nuclear reactor.
The hole drilling method according to any one of claims 1 to 5 .

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