HANDLE, CUTTING TOOL, AND METHOD FOR MANUFACTURING A CUTTING WORKPIECE

Abstract

A tool holder according to an unrestricted aspect of the present disclosure has: a main body, which is in the shape of a rod extending from a first end to a second end along a central axis and has a cavity in the shape of a cylinder extending along the central axis; a cylindrical weight, which is located inside the cavity; and an elastic member, which abuts against the inner surface of the cavity and the weight. The weight has: a first end face, which is located on the first end side; a second end face, which is located on the second end side; and an outer peripheral face, which is connected to the first end face and the second end face. The elastic member has: an annular first elastic member, which abuts against the inner surface and the outer peripheral face; and an annular second elastic member, which abuts against the inner surface and the first end face. The second elastic member is thicker than the first elastic member.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority of Japanese Patent Application No. 2020 - 068404, filed on April 6, 2020, and incorporates the entire disclosure of the prior application herein by reference. Technical Field

[0003] The present disclosure relates to a tool holder used in cutting. Specifically, it relates to a tool holder having a vibration - damping mechanism. Background Art

[0004] Conventionally, a cutting tool having a vibration - damping mechanism has been proposed. In the cutting tool described in Japanese Patent Application Laid - Open No. 2017 - 500507 (Patent Document 1), the main body of the tool holder has a cavity, and an absorber and an elastic element are enclosed in the cavity. The absorber functions as a vibration - damping piece. The elastic element functions as a positioning member for the absorber relative to the cavity. Summary of the Invention

[0005] A tool holder according to an aspect of the present disclosure that is not limited has: a main body that is in a rod shape extending from a first end to a second end along a central axis and has a cylindrical cavity extending along the central axis; a cylindrical weight located inside the cavity; and an elastic member that abuts against the inner surface of the cavity and the weight. The weight has: a first end face located on the first - end side; a second end face located on the second - end side; and an outer peripheral face that connects the first end face and the second end face. The elastic member has: an annular first elastic member that abuts against the inner surface and the outer peripheral face; and an annular second elastic member that abuts against the inner surface and the first end face. The second elastic member is thicker than the first elastic member. Brief Description of the Drawings

[0006] Figure 1 It is a side view of a tool holder (cutting tool) showing an aspect of the present invention that is not limited.

[0007] Figure 2 It is Figure 1 An enlarged view of the area A1 shown.

[0008] Figure 3 It is Figure 1 A cross - sectional view of the III - III section shown.

[0009] Figure 4 It is Figure 3 An enlarged view of the area A2 shown.

[0010] Figure 5 It is Figure 1A three-dimensional view of the weight and elastic member in the handle shown.

[0011] Figure 6 yes Figure 1 A perspective view of the weight in the handle is shown.

[0012] Figure 7 yes Figure 1 A side view of the weight and resilient member in the handle is shown.

[0013] Figure 8 yes Figure 1 Side view of the weight in the handle shown.

[0014] Figure 9 This is a schematic diagram showing one step in a method for producing a machined product according to one non-limiting aspect of the present disclosure.

[0015] Figure 10 This is a schematic diagram showing one step in a method for producing a machined product according to one non-limiting aspect of the present disclosure.

[0016] Figure 11 This is a schematic diagram showing one step in a method for producing a machined product according to one non-limiting aspect of the present disclosure. DETAILED DESCRIPTION

[0017] <Handle>

[0018] Hereinafter, the knife handle 1 of one aspect of the present disclosure which is not limited will be described in detail using the accompanying drawings. However, in the drawings referred to below, only the main components required for explaining the embodiment are simplified for the sake of convenience. Therefore, the knife handle 1 may include any constituent components not shown in the drawings referred to. In addition, the dimensions of the components in the drawings do not accurately show the dimensions of the actual constituent components and the dimensional ratios of the components.

[0019] like Figure 1 As shown in the non-limiting example, the handle 1 may have a rod-shaped body 3 extending from a first end 3a to a second end 3b along a central axis O1. Usually, the first end 3a is referred to as the "front end" and the second end 3b is referred to as the "rear end". The body 3 may be, for example, cylindrical or polygonal. Examples of the material of the body 3 include steel, cast iron, and aluminum alloy.

[0020] The size of the main body 3 can be appropriately set according to the size of the workpiece. For example, the length of the main body 3 along the direction of the central axis O1 can be set to be greater than 60 mm and less than 3500 mm. In addition, the width (diameter) of the main body 3 in the direction orthogonal to the central axis O1 can be set to be greater than 6 mm and less than 250 mm.

[0021] As Figure 2 In an example that is not limited as shown, the main body 3 may have a tool groove 5 located on the first end 3a side and capable of mounting a cutting blade. The tool groove 5 may be a portion recessed on the first end 3a side in the main body 3 before the cutting blade is mounted. The number of tool grooves 5 may be one, or may be multiple. In the case where the number of tool grooves 5 is multiple, the number may also be 2 to 10.

[0022] As Figure 3 In an example that is not limited as shown, the main body 3 may have a cavity 7. The cavity 7 can be used to house a heavy object described below inside. The cavity 7 may extend along the central axis O1. In addition, the cavity 7 may be cylindrical in shape. The cylindrical shape only needs to be a substantially cylindrical shape and does not need to be a strictly cylindrical shape. It should be noted that the cavity 7 may be located closer to the second end 3b than the tool groove 5. In this case, it is easy to ensure the rigidity of the portion of the main body 3 where the tool groove 5 is located.

[0023] The tool holder 1 may have a heavy object 9. The heavy object 9 can function as a vibration damping member. The heavy object 9 may be located inside the cavity 7. In addition, the heavy object 9 may be cylindrical in shape as in an example that is not limited as shown Figures 5 to 8 . The cylindrical shape only needs to be a substantially cylindrical shape and does not need to be a strictly cylindrical shape.

[0024] As the material of the heavy object 9, for example, tungsten alloy etc. can be cited. The specific gravity of the material of the heavy object 9 may be the same as the specific gravity of the material of the main body 3, or may be different. For example, the specific gravity of the material of the heavy object 9 may be greater than the specific gravity of the material of the main body 3.

[0025] The tool holder 1 may have an elastic member 11. The elastic member 11 may abut (contact) against the inner surface 13 of the cavity 7 and the heavy object 9 as in an example that is not limited as shown Figure 4 . The elastic member 11 can function as a positioning member for the heavy object 9 relative to the cavity 7. In addition, the elastic member 11 can also function as a member contributing to the vibration damping performance.

[0026] As the material of the elastic member 11, for example, rubber and resin etc. can be cited. Specifically, natural rubber, butadiene rubber, ethylene rubber, propylene rubber, acrylic rubber, polyurethane rubber, and silicone rubber etc. can be cited.

[0027] Here, the heavy object 9 may have a first end face 15, a second end face 17, and an outer peripheral face 19. The first end face 15 may be located on the first end 3a side. The second end face 17 may be located on the second end 3b side. The outer peripheral face 19 may be connected to the first end face 15 and the second end face 17.

[0028] The elastic member 11 may have a first elastic member 21 and a second elastic member 23. The first elastic member 21 may abut against the inner surface 13 and the outer peripheral surface 19. The second elastic member 23 may abut against the inner surface 13 and the first end surface 15.

[0029] The first elastic member 21 and the second elastic member 23 may be annular. As Figure 5 In an example not limited as shown, the first elastic member 21 and the second elastic member 23 may be circular rings.

[0030] When the elastic member 11 has the above-mentioned first elastic member 21, it is easy to obtain a vibration-proof function in the direction orthogonal to the central axis O1. In addition, when the elastic member 11 has the above-mentioned second elastic member 23, it is easy to obtain a vibration-proof function in the direction along the central axis O1. Therefore, the vibration-proof performance of the tool holder 1 is high.

[0031] The second elastic member 23 may be thicker than the first elastic member 21. In other words, as Figure 4 In an example not limited as shown, the maximum width W12 of the second elastic member 23 may be larger than the maximum width W11 of the first elastic member 21.

[0032] In order to insert a heavy object and an elastic member into the cavity, generally, a tool holder in which a heavy object and an elastic member are sealed in the cavity has: a main body having a recess opening in the direction along the central axis; and a lid for closing the opening of the recess. After the heavy object and the elastic member are inserted into the cavity, the opening of the recess is closed by the lid.

[0033] Compared with the first elastic member 21, it is always easy to apply a large load to the second elastic member 23. When the second elastic member 23 is thicker than the first elastic member 21, the above-mentioned load is easily dispersed over a large range of the second elastic member 23, and the second elastic member 23 is not easily deteriorated. Therefore, the vibration-proof performance of the tool holder 1 is high.

[0034] The maximum width W12 of the second elastic member 23 may be 1.2 times or more the maximum width W11 of the first elastic member 21. In addition, the maximum width W12 may be 7 times or less the maximum width W11. The maximum width W11 may be set to about 0.5 mm to 3 mm. The maximum width W12 may be set to about 0.6 mm to 20 mm.

[0035] The outer diameter of the second elastic member 23 may be the same as the outer diameter of the first elastic member 21, or may be different. The inner diameter of the second elastic member 23 may be the same as the inner diameter of the first elastic member 21, or may be different. For example, as Figure 4As in the unrestricted example shown, it is also possible that the outer diameter of the second elastic member 23 is the same as the outer diameter of the first elastic member 21, and in addition, the inner diameter of the second elastic member 23 is smaller than the inner diameter of the first elastic member 21.

[0036] The inner surface 13 may have a first surface 25, a second surface 27, and an inner peripheral surface 29. The first surface 25 may be located on the first end 3a side. The second surface 27 may be located on the second end 3b side. The inner peripheral surface 29 may be connected to the first surface 25 and the second surface 27. In addition, the first surface 25 may face the first end face 15. The second surface 27 may face the second end face 17. The inner peripheral surface 29 may face the outer peripheral surface 19.

[0037] The second elastic member 23 may abut against the first surface 25 and the inner peripheral surface 29. In this case, the second elastic member 23 can also contribute to the vibration-proof function in the direction orthogonal to the central axis O1, so it is easy to improve the vibration-proof function.

[0038] The hardness of the second elastic member 23 may be the same as or different from the hardness of the first elastic member 21. When the second elastic member 23 is harder than the first elastic member 21, the second elastic member 23, which is always prone to applying a large load, has high durability. Therefore, the durability of the tool holder 1 is high. It should be noted that although the above-mentioned second elastic member 23 is harder than the first elastic member 21, it can also be replaced by the second elastic member 23 having a higher Young's modulus (elastic modulus) than the first elastic member 21.

[0039] The hardness of the first elastic member 21 and the second elastic member 23 is not limited to a specific value. When evaluating hardness by Young's modulus, the Young's modulus of the first elastic member 21 can be set to about 0.5 to 1.5 Mpa. The Young's modulus of the second elastic member 23 can be set to about 1.5 to 5 MPa. Young's modulus can be measured using the nanoindentation method.

[0040] The first end face 15 may have a stepped portion 31 as in Figure 6 an unrestricted example shown. The stepped portion 31 may be located at the outer edge of the first end face 15 connected to the outer peripheral surface 19. The stepped portion 31 may be annular. The stepped portion 31 may also be circular.

[0041] The second elastic member 23 may abut against the stepped portion 31 as in Figure 4 an unrestricted example shown. In this case, the positioning accuracy of the second elastic member 23 with respect to the heavy object 9 is high.

[0042] As in Figure 4As in the unrestricted example shown, in a cross-section including the central axis O1, the center O2 of the cross-section of the second elastic member 23 may be located closer to the second end 3b than the first end face 15. More specifically, the first end face 15 may have a first region 15a located at the position closest to the first end 3a side in the first end face 15, and the center O2 may be located closer to the second end 3b than the first region 15a. In this case, the second elastic member 23 is not easily detached from the stepped portion 31, and the positioning accuracy of the second elastic member 23 with respect to the heavy object 9 is high.

[0043] In a cross-section including the central axis O1, the center O2 of the cross-section of the second elastic member 23 may be located at a position closer to the central axis O1 than the outer peripheral surface 19. In this case, the second elastic member 23 is not easily detached from the stepped portion 31, and the positioning accuracy of the second elastic member 23 with respect to the heavy object 9 is high.

[0044] The outer peripheral surface 19 may be as Figure 6 In the unrestricted example shown, it has a groove 33 extending in the circumferential direction along the central axis O1. The first elastic member 21 may be in contact with the groove 33 as Figure 4 In the unrestricted example shown. In this case, the positioning accuracy of the first elastic member 21 with respect to the heavy object 9 is high.

[0045] The interval W21 between the inner surface 13 and the outer peripheral surface 19 may be wider than the interval W22 between the inner surface 13 and the first end face 15. During cutting, the vibration of the tool holder 1 is more likely to increase in the direction orthogonal to the central axis O1 than in the direction along the central axis O1. When the interval W21 in the direction where vibration is relatively likely to be larger is wider, the effect of suppressing vibration based on the first elastic member 21 is likely to be exerted.

[0046] In a cross-section including the central axis O1, the center O3 of the cross-section of the first elastic member 21 may be located farther from the central axis O1 than the outer peripheral surface 19. In this case, the effect of suppressing vibration of the first elastic member 21 is likely to be exerted.

[0047] The surface roughness of the inner surface 13 may be the same as, or different from, the surface roughness of the outer surface 35 of the main body 3. When the surface roughness of the inner surface 13 is smaller than the surface roughness of the outer surface 35, the first elastic member 21 and the second elastic member 23 are not easily damaged.

[0048] The surface roughness of the inner surface 13 and the outer surface 35 is not limited to a specific value. The surface roughness can be evaluated by the arithmetic mean roughness (Ra). When evaluating the surface roughness by the arithmetic mean roughness (Ra), the arithmetic mean roughness (Ra) of the inner surface 13 can be set to about 1.6 μm to 6.3 μm. The arithmetic mean roughness (Ra) of the outer surface 35 can be set to about 1.6 μm to 6.3 μm. The arithmetic mean roughness (Ra) can be measured in accordance with JIS B0601-2001.

[0049] The number of the first elastic members 21 can be one, and alternatively, it can be plural. When the elastic member 11 has plural first elastic members 21, the number thereof can be 2 to 4.

[0050] The elastic member 11 can have an annular third elastic member 37 that abuts against the inner surface 13 and the second end face 17. In this case, the third elastic member 37 can also contribute to the vibration-proof function in the direction of the central axis O1, and thus it is easy to improve the vibration-proof function.

[0051] The third elastic member 37 can be thicker than the first elastic member 21. Similar to the second elastic member 23, a larger load is always easily applied to the third elastic member 37 than to the first elastic member 21. When the third elastic member 37 is thicker than the first elastic member 21, the above-mentioned load is easily dispersed over a large area of the third elastic member 37, and the third elastic member 37 is not easily deteriorated. Therefore, the vibration-proof performance of the tool holder 1 is high. It should be noted that the structure of the third elastic member 37 can be the same as or different from the structure of the second elastic member 23.

[0052] As Figure 3 In an example that is not limited as shown, the main body 3 can further have: a rod-shaped first member 39 that extends along the central axis O1; and a second member 41 that is located on the side of the first end 3a with respect to the first member 39 and abuts (contacts) against the first member 39. The first member 39 is also referred to as a shank portion and can be a member that can be held by a machine tool. The second member 41 is also referred to as a head and can be a member that can fix a cutting blade. As Figure 2 In an example that is not limited as shown, the above-mentioned tool groove 5 can be located in the second member 41.

[0053] As Figure 3 In an example that is not limited as shown, the first member 39 can have a recess 43 that opens toward the first end 3a. The cavity 7 can also be formed by the recess 43 and the second member 41.

[0054] In the case where the first member 39 has a recess 43, the loading and unloading of the heavy object 9 with respect to the tool holder 1 can be performed through the opening of the recess 43. Further, in the case where a cavity 7 is formed by the recess 43 and the second member 41, since the cavity 7 is located inside the first member 39, it is easy to ensure the rigidity of the second member 41 where a large impact is easily applied during cutting. It should be noted that the first member 39 and the second member 41 may be configured to be detachable.

[0055] The center (center) 7a of the cavity 7 in the direction along the central axis O1 may be located at a position closer to the first end 3a side than the center (center) 39a of the first member 39 in the direction along the central axis O1. In this case, since the cavity 7 constituting the vibration damping mechanism is located near the first end 3a where a large impact is easily applied during cutting, chatter is not likely to occur during cutting. Further, it is easy to ensure the rigidity of the portion of the first member 39 located on the second end 3b side with respect to the center 39a. Therefore, this portion can be held by a machine tool. It should be noted that the entire cavity 7 may also be located at a position closer to the first end 3a side than the center 39a.

[0056] The tool holder 1 may further have a cover for closing the opening of the recess 43. In this case, it is easy to prevent the heavy object 9 from accidentally coming out of the cavity 7. It should be noted that the second member 41 may be used as the cover.

[0057] <Cutting tool>

[0058] Next, taking the case where the cutting tool 101 has the above-described tool holder 1 as an example with respect to an aspect of the present disclosure that is not limited, use Figure 1 and Figure 2 will be described.

[0059] As Figure 1 and Figure 2 shown in an example that is not limited, the cutting tool 101 may include a tool holder 1 and a cutting insert 103 mounted on the tool holder 1. When the cutting tool 101 includes the tool holder 1, the vibration damping performance of the tool holder 1 is high, and thus excellent cutting performance can be exhibited.

[0060] The cutting insert 103 may be simply referred to as the insert 103. Further, the insert 103 may be a polygonal plate shape.

[0061] The insert 103 may have a cutting edge 105. The insert 103 may be located in the tool groove 5 such that the cutting edge 105 protrudes laterally on the first end 3a side of the tool holder 1. The cutting tool 101 can perform cutting by bringing the cutting edge 105 into contact with the workpiece to be cut. It should be noted that the cutting edge 105 may be located at a position farthest from the central axis O1 on the first end 3a side of the main body 3. In this case, only the vicinity of the cutting edge 105 can be brought into contact with the workpiece to be cut.

[0062] The blade 103 may further have a through-hole 107. Additionally, the cutting tool 101 may further include a fixing member 109. The fixing member 109 may be a member for fixing the blade 103 to the tool holder 1. The fixing member 109 may be a screw. It should be noted that the fixing member 109 is not limited to a screw, and for example, it may also be a clamping member or the like.

[0063] The tool holder 1 may have a threaded hole at a position corresponding to the through-hole 107. By inserting a screw as the fixing member 109 into the through-hole 107 of the blade 103 and fixing the screw to the threaded hole of the tool holder 1, the blade 103 can be fixed to the tool holder 1. It should be noted that the through-hole 107 and the threaded hole may extend in a direction orthogonal to the central axis O1.

[0064] Examples of the material of the blade 103 include cemented carbide and cermet. Examples of the composition of the cemented carbide include WC-Co, WC-TiC-Co, and WC-TiC-TaC-Co. WC-Co can be produced by adding cobalt (Co) powder to tungsten carbide (WC) and sintering. WC-TiC-Co can be obtained by adding titanium carbide (TiC) to WC-Co. WC-TiC-TaC-Co can be obtained by adding tantalum carbide (TaC) to WC-TiC-Co.

[0065] Additionally, cermet may be a sintered composite material in which a metal is compounded in a ceramic component. Specifically, examples of cermet include cermet mainly composed of titanium compounds such as titanium carbide (TiC) or titanium nitride (TiN).

[0066] <Method for manufacturing a machined product>

[0067] Next, use Figures 9 to 11 A method for manufacturing a machined product 203 according to an aspect of the present disclosure that is not limited will be described.

[0068] The method for manufacturing the machined product 203 may include the following steps (1) to (4).

[0069] (1) As Figure 9 shown in an example that is not limited, prepare a cutting tool 101 and a workpiece 201 represented by the above-described embodiment that is not limited;

[0070] (2) Rotate the workpiece 201;

[0071] (3) As Figure 10 shown in an example that is not limited, bring the workpiece 201 and the cutting tool 101 into contact with each other; and

[0072] (4) As Figure 11 shown in an unrestricted example, separate the workpiece 201 and the cutting tool 101 from each other.

[0073] Specifically, as the material of the workpiece 201 prepared in the process of (1), for example, carbon steel, alloy steel, stainless steel, cast iron, non-ferrous metal, etc. can be cited.

[0074] In the process of (2), as Figure 9 shown in an unrestricted example, rotate the workpiece 201 with its rotation axis O4 as the reference.

[0075] In the process of (3), first, the cutting tool 101 can be moved in the direction of arrow Y1 to relatively approach the rotating workpiece 201. Then, as Figure 10 shown in an unrestricted example, the cutting tool 101 can be brought into contact with the rotating workpiece 201. Then, the cutting edge 105 can be brought into contact with the workpiece 201 to machine the workpiece 201.

[0076] In the process of (4), as Figure 11 shown in an unrestricted example, by moving the cutting tool 101 in the direction of arrow Y2, the cutting tool 101 is separated from the workpiece 201 to obtain the machined product 203.

[0077] In the manufacturing method of the machined product 203, when using the cutting tool 101 having the tool shank 1, since the vibration damping performance of the tool shank 1 is high, the occurrence of chatter can be suppressed and the workpiece 201 can be machined with excellent machining accuracy. As a result, a machined product 203 having a highly accurate machined surface can be obtained.

[0078] It should be noted that in the process of (3), the workpiece 201 can be brought closer to the cutting tool 101. In the process of (4), the workpiece 201 can be moved away from the cutting tool 101. In the case of continuing the machining, the state of rotating the workpiece 201 can be maintained, and the process of bringing the cutting edge 105 into contact with different parts of the workpiece 201 can be repeated.

[0079] The above has exemplified the manufacturing methods of the tool shank 1, the cutting tool 101, and the machined product 203 of the unrestricted embodiments, but the present disclosure is not limited to the above embodiments, and of course, any method can be adopted without departing from the gist of the present disclosure.

[0080] For example, in the above-described unrestricted embodiment, the cutting tool 101 is a turning tool, but instead, the cutting tool 101 may be, for example, a milling tool. In the case where the cutting tool 101 is a milling tool, the cutting tool 101 may also be rotated in the step (2) of the manufacturing method of the workpiece 203.

[0081] Description of Reference Numerals

[0082] 1... tool shank

[0083] 3... body

[0084] 3a.. first end

[0085] 3b.. second end

[0086] 5... tool groove

[0087] 7... cavity

[0088] 7a.. center (central)

[0089] 9... weight

[0090] 11... elastic member

[0091] 13... inner surface

[0092] 15... first end face

[0093] 15a.. first region

[0094] 17... second end face

[0095] 19... outer peripheral surface

[0096] 21... first elastic member

[0097] 23... second elastic member

[0098] 25... first face

[0099] 27... second face

[0100] 29... inner peripheral surface

[0101] 31... step portion

[0102] 33... groove

[0103] 35... outer surface

[0104] 37... third elastic member

[0105] 39... first member

[0106] 39a..Center (central)

[0107] 41...Second member

[0108] 43...Recess

[0109] 101...Cutting tool

[0110] 103...Cutting insert (insert)

[0111] 105...Cutting edge

[0112] 107...Through hole

[0113] 109...Fixing member (screw)

[0114] 201...Workpiece to be cut

[0115] 203...Machined product

[0116] O1...Center axis

[0117] O2...Center of cross-section of second elastic member

[0118] O3...Center of cross-section of first elastic member

[0119] O4...Rotation axis.

Claims

1. A tool holder, wherein, the tool holder has: a main body, which is in a rod shape extending from a first end to a second end along a central axis, and has a cavity in a cylindrical shape extending along the central axis; a cylindrical weight, which is located inside the cavity; and an elastic member, which abuts against the inner surface of the cavity and the weight, the weight has: a first end face, which is located on the first end side; a second end face, which is located on the second end side; and an outer peripheral face, which connects the first end face and the second end face, the elastic member has: an annular first elastic member, which abuts against the inner surface and the outer peripheral face; an annular second elastic member, which abuts against the inner surface and the first end face; and an annular third elastic member, which abuts against the inner surface and the second end face, the second elastic member is thicker than the first elastic member, in a cross section including the central axis, the center of the cross section of the first elastic member is located at a position farther from the central axis than the outer peripheral face.

2. The tool holder according to claim 1, wherein, the inner surface has: a first face, which is located on the first end side; a second face, which is located on the second end side; and an inner peripheral face, which connects the first face and the second face, the second elastic member abuts against the first face and the inner peripheral face.

3. The tool holder according to claim 1 or 2, wherein, the second elastic member is harder than the first elastic member.

4. The tool holder according to claim 1 or 2, wherein, the first end face has an annular step portion located at an outer edge connecting to the outer peripheral face, the second elastic member abuts against the step portion.

5. The tool holder according to claim 4, wherein, in a cross section including the central axis, the center of the cross section of the second elastic member is located at a position closer to the second end than the first end face.

6. The tool holder according to claim 4, wherein, in a cross section including the central axis, the center of the cross section of the second elastic member is located at a position closer to the central axis than the outer peripheral face.

7. The tool holder according to claim 1 or 2, wherein, the interval between the inner surface and the outer peripheral face is wider than the interval between the inner surface and the first end face.

8. The tool holder according to claim 1 or 2, wherein, the surface roughness of the inner surface is less than the surface roughness of the outer surface of the main body.

9. A cutting tool, wherein, the cutting tool includes: the tool holder according to any one of claims 1 to 8; and a cutting blade, which is mounted on the tool holder.

10. A method for manufacturing a machined product, wherein, the method for manufacturing the machined product includes: a step of rotating at least one of the cutting tool according to claim 9 and the workpiece; a step of bringing the cutting tool into contact with the workpiece; and a step of separating the cutting tool from the workpiece.

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