Waring device

Abstract

To provide a whirling device which can achieve the long service life of a tool.SOLUTION: A whirling device 10a includes a chuck 11 capable of rotating rod-like workpiece W around a first axis, and a tool holder 14a which has a plurality of tool holding parts 30a configured to hold approximately rod-like tools 20a having cutting edge parts 201a provided at the end in a long direction, and can rotate the plurality of tools 20a held by the plurality of tool holding parts 30a around a second axis A2 at a twist position to the first axis A2, wherein the tool holding part 30a is configured to changeably hold the position in a radial direction of a circle around the second axis A2, in a direction at which the cutting edge parts 201a are positioned on a side close to the second axis A2.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present invention relates to a threading device.

Background Art

[0002] As a manufacturing device for products having spiral grooves on the outer peripheral surface such as screws, a threading device (threading machine) is known (see, for example, Patent Document 1). The threading device is provided with an opening through which a workpiece can be inserted, and includes a tool holder that holds a plurality of cutting blade portions (tools) so as to project toward the inner peripheral side of the opening. Then, the threading device is configured to be able to form a spiral groove on the outer peripheral surface of the workpiece by rotating the workpiece and the tool holder synchronously with the workpiece inserted through the opening of the tool holder.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] (Problems to be Solved by the Invention) Conventionally, when the cutting edge of a tool in a whirring machine is ground, the position of the cutting edge relative to the workpiece changes. Therefore, when the cutting edge wears down, the tool is replaced without regrinding. For this reason, extending the tool's lifespan was required to reduce tool costs. In addition, conventional whirring machines could not reduce the distance from the chuck end face to the tool's cutting edge, resulting in wasted material (parts that could not be machined by the tool) in the workpiece. Specifically, the cutting edge of the tool is located near the center of the roughly disc-shaped tool holder, but because the chuck end face and the tool holder end face are inclined relative to each other, if the tool holder is brought close to the chuck, the outer circumference of the tool holder comes into contact with (interferes with) the chuck, making it impossible to bring the center of the tool holder close to the chuck. Furthermore, since a helical groove cannot be formed in the part of the workpiece from the chuck end face to the tool's cutting edge, this part becomes wasted.

[0005] This invention has been made in view of the above circumstances, and one of its objectives is to extend the lifespan of the tools in the whirring device. Another objective of this invention is to reduce workpiece waste (parts that cannot be machined by the tool).

[0013] (Means for solving the problem) To solve the above problems, the Waring apparatus according to the present invention is A chuck that can rotate a rod-shaped workpiece around a first axis, The tool holder comprises a plurality of tool holding parts configured to hold tools having cutting edges, and the plurality of tools held in the plurality of tool holding parts can be rotated about a second axis that is twisted with respect to the first axis, One end of the second axis of the tool holder, the end closer to the chuck, is provided with a substantially frustoconical tapered portion whose outer diameter decreases as it approaches the chuck, with the second axis as the center. In a view perpendicular to the second axis, the angle η between the second axis and the surface of the tapered portion is given by the following formula: 1 This is shown by ). 90°>η≧80°-θ Formula( 1 ) θ: The angle between the first axis and the projected second axis when the second axis is projected onto a plane that includes the first axis and is parallel to the second axis.

[0014] According to the present invention, as described above, the distance from the end face of the chuck to the center of the tool holder and its vicinity (the area where the cutting edge is located) can be reduced compared to a configuration in which the end face of the tool holder is flat. Therefore, workpiece waste (the portion that cannot be machined by the tool) can be reduced.

[0015] The tool holder is provided with a workpiece insertion hole that allows the workpiece to be loosely inserted, is coaxial with the second axis, and penetrates the center of the tapered portion. The tool holding portion is provided on the surface of the tapered portion so as to be able to hold the tool such that the cutting edge portion protrudes towards the inner circumference of the workpiece insertion hole. This configuration can be applied.

[0016] With this configuration, when the tool holder is brought close to the chuck, the cutting edge of the tool can be reduced in relation to the end face of the chuck. This enhances the effect of reducing workpiece waste (the part that cannot be machined by the tool).

[0017] The tool has a rod-like structure with the cutting edge portion provided at one end in the longitudinal direction. The tool holder is configured to hold the tool in a orientation in which the cutting edge is located closer to the second axis, and to hold the tool in a manner that allows for changes in its radial position on a circle centered on the second axis. This configuration can be applied.

[0018] With this configuration, the radial position of the circle centered on the tool's second axis can be changed, thus allowing adjustment of the distance from the second axis to the cutting edge of the tool. Therefore, if the tool's length is shortened due to grinding the cutting edge, the distance from the second axis to the cutting edge can be restored to the same distance as before grinding by changing the radial position of the circle centered on the tool's second axis. Consequently, if the cutting edge wears down, it can be regenerated by grinding, allowing the tool to continue to be used and thus extending its lifespan.

[0019] The tool holder is provided with a workpiece insertion hole that allows the workpiece to be loosely inserted and is coaxial with the second axis, The tool holding portion includes a tool holding hole into which the tool can be inserted, and which extends from the inner circumferential surface of the workpiece insertion hole in a direction that is inclined at the same angle η as the angle η between the second axis and the surface of the tapered portion with respect to the second axis. This configuration can be applied.

[0020] With this configuration, the radial position of the circle centered on the tool's second axis can be changed by sliding the tool relative to the tool holder while it is inserted into the tool holding hole. Therefore, positioning of the cutting edge is easy. [Brief explanation of the drawing]

[0021] [Figure 1A] Figure 1A is a schematic diagram showing the configuration of the Waring apparatus according to the first embodiment. [Figure 1B] Figure 1B is a schematic diagram showing the configuration of the Waring apparatus according to the first embodiment. [Figure 1C] Figure 1C is a schematic diagram showing the configuration of the Waring apparatus according to the first embodiment. [Figure 2] Figure 2 is a schematic partial cross-sectional view showing the configuration of the tool and tool holder of the Waring apparatus according to the first embodiment. [Figure 3A] Figure 3A is a schematic diagram showing the configuration of the Waring device according to the second embodiment. [Figure 3B] FIG. 3B is a schematic diagram showing the configuration of the working device according to the second embodiment. [Figure 4] FIG. 4 is a diagram schematically showing the configuration of the tool holder of the working device according to the second embodiment. [Figure 5] FIG. 5 is a diagram schematically showing the configuration of the working device according to the third embodiment. [Figure 6A] FIG. 6A is a schematic diagram showing the configuration of the tool and the tool holder of the working device according to the third embodiment. [Figure 6B] FIG. 6B is a schematic diagram showing the configuration of the tool and the tool holder of the working device according to the third embodiment. [Figure 7] FIG. 7 is a schematic diagram showing the tool alignment jig and the tool alignment method.

Mode for Carrying Out the Invention

[0022] (First Embodiment) The first embodiment is a form in which the long life of the tool can be achieved. FIGS. 1A, 1B, and 3 are schematic diagrams showing the configuration of the main part of the working device 10a according to the first embodiment. Note that FIGS. 1A and 1B are perspective views, and FIG. 1C is a top view. As shown in these figures, the working device 10a includes a chuck 11, a center 12, a center rest 13, and a tool holder 14a (sometimes referred to as a working head). Further, the working device 10a includes a schematic rotation drive mechanism (hereinafter sometimes referred to as a chuck drive mechanism) configured to rotate the chuck 11 about a predetermined straight line, and a rotation drive mechanism (hereinafter sometimes referred to as a tool holder drive mechanism) configured to rotate the tool holder 14a about a predetermined straight line.

[0023] Hereinafter, the rotational centerline (axis) of the chuck 11 driven by the chuck drive mechanism will be referred to as the first axis A1, and the rotational centerline (axis) of the tool holder 14a driven by the tool holder drive mechanism will be referred to as the second axis A2. It can also be said that the first axis A1 is the rotational centerline of the workpiece W supported by the chuck 11. Furthermore, it can be said that the second axis A2 is the rotational centerline of the multiple tools 20a (described later). The first axis A1 and the second axis A2 are in a twisted position. That is, the first axis A1 and the second axis A2 are neither parallel nor intersecting. When the second axis A2 is projected onto a plane that includes the first axis A1 and is parallel to the second axis A2, in a direction perpendicular to this plane, the first axis A1 and the projected second axis A2 are inclined toward each other at a predetermined angle θ (see Figure 1C). This predetermined angle θ (where the smaller of the angles formed by the first axis A1 and the second axis A2) is sometimes referred to as the axial inclination angle θ.

[0024] The chuck 11 is configured to support (grip) one end of a rod-shaped (for example, cylindrical or cylindrical) workpiece W in the longitudinal direction. The center 12 and tailstock 13 are configured to support the end of the workpiece W in the longitudinal direction opposite to the side supported by the chuck 11. The chuck 11 is configured to rotate by rotational power transmitted from the chuck drive mechanism, thereby rotating the workpiece W. Conventional known configurations can be applied to the chuck 11, center 12, tailstock 13, and chuck drive mechanism.

[0025] Figure 2 is a schematic diagram showing the configuration of the tool 20a and the tool holder 14a. As shown in Figure 2, the tool 20a has a rod-shaped configuration. One end of the tool 20a in the longitudinal direction is provided with a cutting edge portion 201a, which is the part that cuts the workpiece W (the part with the cutting edge). The cutting edge portion 201a has a tapered shape, for example, with its width decreasing towards the end in the longitudinal direction. The specific shape and dimensions of the cutting edge portion 201a are set according to the product manufactured by the whirring device 10a and are not particularly limited. The part of the tool 20a other than the cutting edge portion 201a has a rod-shaped configuration with a substantially equal cross-section. In this embodiment, the part of the tool 20a other than the cutting edge portion 201a is shown to be a rod-shaped configuration with a substantially quadrilateral cross-section. However, the cross-sectional shape of the part other than the cutting edge portion 201a is not particularly limited. Also, the cutting edge portion 201a and the part other than the cutting edge portion 201a are integrally molded from the same material.

[0026] The tool holder 14a has a roughly disc-like shape and is assembled to the whirring device 10a in a position and orientation where its centerline coincides with the second axis A2. In Figure 2, the upper right side (the side furthest from the plane of the paper) is the side closer to the chuck 11.

[0027] The tool holder 14a is provided with a workpiece insertion hole 141 and a plurality of tool holding parts 30a. The workpiece insertion hole 141 is located in the center of the tool holder 14a and is a through-hole with a substantially circular cross-section that penetrates in the thickness direction (in other words, a through-hole coaxial with the second axis A2), and is configured to allow the workpiece W to be loosely inserted.

[0028] Multiple tool holders 30a are arranged at approximately equal intervals in the circumferential direction of a circle centered on the second axis A2. The number of tool holders 30a provided by the tool holder 14a is not particularly limited. Each tool holder 30a is configured to hold one tool 20a. Each tool holder 30a includes a tool holder hole 301a and a screw hole 302a. The tool holder hole 301a is configured to allow the insertion of a tool 20a and to allow the inserted tool 20a to be moved in the direction of the centerline (extension direction) of the tool holder hole 301a. The tool holder hole 301a is a hole that extends from the inner circumferential surface 142 of the workpiece insertion hole 141 in the direction of a plane perpendicular to the second axis A2. Specifically, the tool holding hole 301a is a through-hole with approximately equal cross-sections that connects the inner circumferential surface 142 of the workpiece insertion hole 141 and the outer circumferential surface 143 of the tool holder 14a (the surface corresponding to the side of the disc when the tool holder 14a is considered to be approximately disc-shaped). The center line of the tool holding hole 301a is a straight line.

[0029] The screw hole 302a is provided so as to connect the inner circumferential surface of the tool holding hole 301a with one end face of the tool holder 14a (in this embodiment, the end face opposite to the end face facing the chuck 11). In other words, the screw hole 302a is configured so that a screw 31 can be screwed into it from one end face of the tool holder 14a, and the tip of the screwed screw 31 can protrude into the inside of the tool holding hole 301a. Although Figure 2 shows a configuration in which two screw holes 302a are provided for one tool holding hole 301a, the number of screw holes 302a provided for one tool holding hole 301a is not particularly limited. One screw hole 302a may be provided for one tool holding hole 301a, or three or more screw holes 302a may be provided.

[0030] As shown in Figure 2, the tool 20a is inserted into the tool holding hole 301a such that the cutting edge portion 201a protrudes from the inner circumferential surface 142 of the workpiece insertion hole 141 of the tool holder 14a. Then, a screw 31 is screwed into the screw hole 302a from one end face of the tool holder 14a, and the tip of the screw 31 is pressed against the side of the tool 20a, thereby attaching (holding) the tool 20a to the tool holder 14a. With this configuration, when the screw 31 is not fastened, the radial position of the tool 20a on a circle centered on the second axis A2 (especially the position of the cutting edge portion 201a) can be adjusted (or the position of the tool 20a can be changed) by sliding the tool 20a in the direction of the centerline (extension direction) of the tool holding hole 301a. Thus, each tool holder 30a is configured to hold each tool 20a in such a way that the cutting edge portion 201a of each tool 20a is positioned closer to the second axis A2, and its radial position on a circle centered on the second axis A2 can be changed, but its circumferential position on a circle centered on the second axis A2 cannot be changed.

[0031] Here, the operation of the Waring device 10a will be briefly explained. With the workpiece W supported by the chuck 11 and tailstock 13, the workpiece W is rotated around the first axis A1. Also, with multiple tools 20a attached to the tool holder 14a, the tool holder 14a is rotated around the second axis A2. Note that the rotational speed of the workpiece W and the rotational speed of the tool holder 14a do not need to be asynchronous. The Waring device 10a then moves the workpiece W and the tool holder 14a relative to each other in a direction parallel to the first axis A1 at a speed synchronized with the rotational speed of the workpiece W. Specifically, the relative speed of the workpiece W and the tool holder 14a is the speed at which the workpiece W and the tool holder 14a move relatively a distance of "(number of spiral grooves to be formed in the product) × (distance between adjacent spiral grooves in the direction of the first axis A1)" for each rotation of the workpiece W.

[0032] Then, by bringing the cutting edge portion 201a of the rotating tool 20a into contact with the outer circumferential surface of the workpiece W, the material of the workpiece W at the contact point is removed. As a result, tooth grooves are formed on the outer circumferential surface of the workpiece W, extending in a direction inclined by an angle corresponding to the axial inclination angle θ with respect to the first axis A1. Then, by moving the workpiece W and the tool holder 14a relative to each other in a direction parallel to the first axis A1 at a speed synchronized with the rotational speed of the workpiece W, spiral grooves are formed on the outer circumferential surface of the workpiece W.

[0033] According to the first embodiment, the lifespan of the tool 20a can be extended. In other words, with conventional tools, the distance between the cutting edge and the workpiece changes when the cutting edge is sharpened, so the tool was replaced without resharpening when the cutting edge wore down. In contrast, according to the first embodiment, when the cutting edge 201a of the tool 20a wears down, the tool 20a can be continued to be used by sharpening and regenerating the cutting edge 201a. In particular, if the cutting edge 201a and the parts other than the cutting edge 201a are integrally molded from the same material, the tool 20a can be repeatedly sharpened until it can no longer be held by the tool holder 14a, thus making it easier to extend the lifespan of the tool 20a. In addition, the tool holding portion 30a of the tool holder 14a is configured to change its position in a direction perpendicular to the second axis A2 of the tool 20a. Therefore, for example, when using a tool 20a whose length has been shortened by grinding the cutting edge portion 201a, the distance from the second axis A2 to the cutting edge portion 201a can be made the same as the distance before grinding by adjusting the radial position of the circle centered on the second axis A2 of the tool 20a.

[0034] Furthermore, according to the first embodiment, with the tool 20a inserted into the tool holding hole 301a, the radial position of the circle centered on the second axis A2 of the tool 20a can be changed by sliding the tool 20a relative to the tool holder 14a. Therefore, the positioning of the tool 20a (in other words, the positioning of the cutting edge portion 201a) is easy.

[0035] (Second embodiment) Next, a second embodiment will be described. The second embodiment is a configuration that can reduce waste of workpiece W. In the second embodiment, the whirring device 10b differs from the whirring device 10a of the first embodiment in the configuration of the tool 20b and the tool holder 14b, but other common configurations can be applied. For this reason, in the following description, components common to the first embodiment will be denoted by the same reference numerals as in the first embodiment, and their descriptions may be omitted.

[0036] Figures 3A and 3B schematically show the configuration of the main parts of the whirring device 10b according to the second embodiment. Figure 4 is a schematic diagram showing the configuration of the tool holder 14b of the whirring device 10b according to the second embodiment. Note that Figure 3A is a perspective view and Figure 3B is a top view. Also, in Figure 3B, the tool 20b is omitted, and the external shape and position of the conventional tool holder 91 are shown by dashed lines. The tool holder 91 according to the comparative example has a substantially disc shape with an end face that is substantially flat.

[0037] The tool 20b is a conventionally known tool equipped with a cutting edge portion 201b.

[0038] As shown in Figures 3A, 3B, and 4, the portion of the tool holder 14b closest to the chuck 11 has a tapered shape in which the outer diameter gradually decreases as it approaches the end face. Specifically, with respect to the second axis A2 direction, the portion of the tool holder 14b closest to the chuck 11 has a roughly frustoconical shape, while the remaining portion has a roughly cylindrical shape. For this reason, the tool holder 14b can also be described as having an outer shape in which a frustoconical and a cylinder are joined to each other coaxially in the direction of the centerline. Hereinafter, this tapered portion (the roughly frustoconical portion) may be referred to as the tapered portion 144.

[0039] As shown in Figure 3B, the tapered portion 144 has a roughly frustum-shaped form centered on the second axis A2. And, in a view perpendicular to the second axis A2, the angle η (i.e., the angle corresponding to the apex angle of the frustum) between the second axis A2 and the outer surface of the tapered portion 144 (the surface corresponding to the side (outer surface) of the frustum, and the surface facing the chuck 11 (or, it can also be said to be the surface located on the chuck 11 side with respect to the direction of the second axis A2 of the tapered portion 144)) is, 90°>η≧80°-(Axis crossing angle θ) Hereafter, this angle η may be referred to as the vertex angle η. Figure 3B shows an example where the vertex angle η is (90° - (axis inclination angle θ)), but the vertex angle η may be smaller than (90° - (axis inclination angle θ)). However, since there is no effect from the vertex angle η being significantly smaller than (90° - (axis inclination angle θ)), it is preferable that the vertex angle η is (80° - (axis intersection angle θ)) or greater.

[0040] The tool holder 14b is provided with a workpiece insertion hole 141 and a plurality of tool holding parts 30b. The workpiece insertion hole 141 is a through hole with a substantially circular cross-section located in the center of the tool holder 14b (in other words, a through hole coaxial with the second axis A2), and is configured to allow the workpiece W to be loosely inserted.

[0041] Multiple tool holders 30b are configured to hold the tool 20b on the outer surface of the tapered portion 144 (the surface corresponding to the side of the frustum of the cone). These multiple tool holders 30b are arranged at approximately equal intervals in the circumferential direction of a circle centered on the second axis A2. Since conventionally known tools are used for the tool 20b, conventionally known configurations are also applied to the tool holders 30b. For example, the outer surface of the tapered portion 144 of the tool holder 14b is provided with a recess 303 into which the tool 20b can be fitted, and the recess 303 is provided with a screw hole 304 for screwing the tool 20b in place. The tool 20b is then positioned relative to the tool holder 14b by being fitted into this recess 303, and the tool 20b is fixed to the tool holder 14b by screwing in the screw 32. The tool 20b, fixed to the tool holder 14b, is held in the tool holder 14b such that, in a view along the second axis A2, its cutting edge portion 201b protrudes from the tip of the tapered portion 144 towards the inner circumference of the workpiece insertion hole 141.

[0042] According to the second embodiment, the cutting edge portion 201b can be brought closer to the chuck 11 compared to a conventional tool holder 91 having a substantially disc shape. Specifically, since the cutting edge portion 201b of the tool 20b is located near the center of the tool holder 14b (the part close to the second axis A2), in order to reduce the distance L from the end face of the chuck 11 to the cutting edge portion 201a (in Figure 3B, the symbol T1 indicates the trajectory of the cutting edge portion 201b, and the distance L indicates the average distance from the end face of the chuck 11 to the cutting edge portion 201b), it is necessary to bring the center of the tool holder 14b and the parts near it closer to the chuck 11.

[0043] However, the first axis A1 and the second axis A2 are inclined relative to each other at a predetermined axial inclination angle θ. Therefore, in the conventional substantially disc-shaped tool holder 91, the outer circumference of the tool holder 91 (the part indicated by the symbol P in Figure 3B) interferes with the chuck 11, making it impossible to bring the center of the tool holder 91 close to the end face of the chuck 11. Consequently, in such a configuration, the distance M from the end face of the chuck 11 to the cutting edge (in Figure 3B, the symbol T2 indicates the trajectory of the cutting edge, and the distance M indicates the average distance from the end face of the chuck 11 to the cutting edge) becomes large.

[0044] In contrast, according to the second embodiment, compared to a configuration in which the tool holder 14b does not have a tapered portion 144, interference between the outer circumference of the tool holder 14b and the chuck 11 is reduced. As a result, the center of the tool holder 14b can be brought closer to the chuck 11. Therefore, compared to a conventional configuration in which the tool holder 91 is substantially disc-shaped (a configuration in which the tapered portion 144 is not provided), the distance L from the end face of the chuck 11 to the cutting edge portion 201b can be made smaller than the distance M with the conventional tool holder 91. As a result, workpiece waste (parts that cannot be machined by the tool 20b) can be reduced.

[0045] Furthermore, if the apex angle η is (90° - (axis inclination angle θ)), the outer surface of the tapered portion 144 of the tool holder 14b can be made approximately parallel to the end face of the chuck 11. This allows the central part of the tool holder 14b to approach the chuck 11 without the outer peripheral portion of the tool holder 14b interfering with the chuck 11. Therefore, it is preferable that the apex angle η is (90° - (axis inclination angle θ)) or less. However, even if the apex angle η is significantly smaller than (90° - (axis inclination angle θ)), the effect of "preventing the outer peripheral portion of the tool holder 14b from interfering with the chuck 11" does not increase. For this reason, it is preferable that the apex angle η is (80° - (axis inclination angle θ)) or more.

[0046] Furthermore, in this embodiment, the tool holding portion 30b is provided on the outer surface of the tapered portion 144 (the surface corresponding to the side of the frustocone and facing the chuck 11). With this configuration, when the tool holder 14b is brought close to the chuck 11, the cutting edge portion 201b of the tool 20b can be reduced from the end face of the chuck 11.

[0047] Furthermore, if the distance from the chuck 11 to the cutting edge portion 201b is large, the workpiece W is more susceptible to elastic deformation due to the force exerted on it by the cutting edge portion 201b of the tool 20b. As a result, machining accuracy may decrease. Also, if the workpiece W is easily elastically deformed, self-excited vibration (chatter vibration) is more likely to occur during machining. In contrast, according to the second embodiment, the distance from the chuck 11 to the cutting edge portion 201b can be reduced, thereby reducing the amount of elastic deformation of the workpiece W. Therefore, machining accuracy can be improved, and the occurrence of self-excited vibration can be prevented or suppressed.

[0048] (Third embodiment) Next, a third embodiment will be described. The third embodiment is a combination of the first and second embodiments, and is a configuration that can extend the lifespan of the tool 20c and reduce waste of the workpiece W. Compared to the first and second embodiments, the configuration of the tool 20c and the tool holder 14c differs in the third embodiment, but other common configurations can be applied. For this reason, in the following description, components common to the first and second embodiments will be denoted by the same reference numerals as in the first and second embodiments, and their descriptions may be omitted.

[0049] Figure 5 is a schematic diagram showing the configuration of the Waring device 10c according to the third embodiment. Figures 6A and 6B are schematic diagrams showing the configuration of the tool and tool holder.

[0050] The tool 20c has a rod-like structure. A cutting edge portion 201c is provided at one end of the tool 20c in the longitudinal direction. The shape and dimensions of the cutting edge portion 201c are determined according to the dimensions and shape of the helical groove formed in the workpiece W, and are not specifically limited. The parts of the tool 20c other than the cutting edge portion 201c have a rod-like structure with substantially equal cross-sections. Furthermore, the cutting edge portion 201c and the parts other than the cutting edge portion 201c are integrally molded from the same material.

[0051] Similar to the second embodiment, the tool holder 14c has a tapered portion 144 on the side closer to the chuck 11 in the linear direction. In this embodiment, the tool holder 14c has a shape in which a hollow, substantially frustoconical portion and a substantially cylindrical portion are coaxially joined in the axial direction. The substantially frustoconical portion is the tapered portion 144. The same angle η as in the second embodiment is applied to the apex angle η of the tapered portion 144. The tool holder 14c is provided with a workpiece insertion hole 141 and a plurality of tool holding portions 30c. The workpiece insertion hole 141 is a through hole with a substantially circular cross-section (in other words, a through hole coaxial with the second axis A2) provided at the center of the tool holder 14c, and is configured to allow the workpiece W to be loosely inserted and passes through the center of the tapered portion 144.

[0052] The multiple tool holding portions 30c are each provided with a tool holding hole 301c and a screw hole 302c, similar to the first embodiment. The tool holding hole 301c is a through hole with the same cross-section that connects the inner circumferential surface 142 of the workpiece insertion hole 141 and the outer circumferential surface 143 of the tool holder 14c (the surface corresponding to the side of a cylinder). The center line of the tool holding hole 301c is a straight line and is inclined at a predetermined angle with respect to the second axis A2. Specifically, this angle is such that when the center line of the tool holding hole 301c is projected onto a plane that includes the second axis A2 and is parallel to the tool holding hole 301c, the angle between the second axis A2 and the projected straight line is the same as the vertex angle η. It can also be said that the centerline of the tool holding hole 301c is inclined with respect to the second axis A2 such that the opening of the tool holding hole 301c located on the inner circumferential surface 142 of the workpiece insertion hole 141 is located closer to the chuck 11 than the opening of the tool holding hole 301c located on the outer circumferential surface of the tool holder 14c of the tool holding hole 301c.

[0053] The screw hole 302c may be the same as in the first embodiment. Specifically, the screw hole 302c is provided to open on the inner surface side of the tapered portion 144 (the side opposite to the side facing the chuck 11). The multiple tool holding portions 30c are arranged at approximately equal intervals in the circumferential direction of a circle centered on the second axis A2.

[0054] As shown in Figures 6A and 6B, the tool 20c is inserted into the tool holder 14c such that the cutting edge portion 201c of the tool 20c protrudes from the inner circumferential surface 142 of the workpiece insertion hole 141 of the tool holder 14c. Furthermore, the tool 20c can be attached (held) to the tool holder 14c by screwing the screw 31 into the screw hole 302c from the inner surface side of the tapered portion 144 of the tool holder 14c and pressing the tip of the screw 31 against the side of the tool 20c. With this configuration, the distance from the second axis A2 to the cutting edge portion 201c can be changed by sliding the tool 20c in the direction of the centerline of the tool holding hole 301c. Thus, the tool holder 14c is configured to hold a plurality of substantially rod-shaped tools 20c, each having a cutting edge portion 201c at its longitudinal end, in an orientation where the cutting edge portion 201c is positioned closer to the second axis A2, and the distance from the second axis A2 to the cutting edge portion 201c can be changed.

[0055] Furthermore, as described above, the center line of the tool holding hole 301c is inclined at a predetermined angle with respect to the second axis A2. Therefore, when the tool 20c is inserted into the tool holding hole 301c in such a manner that the cutting edge portion 201c protrudes from the inner circumferential surface 142 of the workpiece insertion hole 141, the cutting edge portion 201c protrudes from the end face of the tapered portion 144 (the portion corresponding to the upper base of the frustocone) when viewed in a direction perpendicular to the second axis A2 (see Figure 7).

[0056] According to the third embodiment, the same effects as the first and second embodiments can be achieved. That is, when the cutting edge portion 201c of the tool 20c is worn, the tool 20c can be continued to be used by grinding and regenerating the cutting edge portion 201c. In this case, the cutting edge portion 201c is ground so that its dimensions and shape are the same as the cutting edge portion 201c at the time of the previous grinding. When using a tool 20c whose length has been shortened by grinding the cutting edge portion 201c, the distance from the second axis A2 of the tool 20c to the cutting edge portion 201c can be made the same as before the tool 20c was ground by adjusting the radial position of the circle centered on the second axis A2 of the tool 20c. In addition, since the end of the tool holder 14c on the side closer to the chuck 11 has a substantially frustoconical shape, the cutting edge portion 201c of the tool 20c can be brought closer to the chuck 11 compared to a configuration in which the tool holder 14c has a substantially disc shape.

[0057] In particular, in this embodiment, the inner circumferential surface 142 of the workpiece insertion hole 141 from which the cutting edge portion 201c of the tool 20c protrudes is provided at the tip of the tapered portion 144. More specifically, the tapered portion 144 has a substantially frustoconical shape with a predetermined thickness and a hollow interior. The tool holding hole 301c is provided inside the wall thickness of the tapered portion 144. Therefore, the opening of the tool holding hole 301c on the inner circumferential surface 142 of the workpiece insertion hole 141 is located near the end of the tapered portion 144 on the side closer to the chuck 11 (near the portion corresponding to the upper base of the frustoconical). Consequently, the distance from the chuck 11 to the cutting edge portion 201c can be reduced. Thus, waste of workpiece W can be reduced. Furthermore, the amount of elastic deformation of the workpiece W can be reduced, and the occurrence of self-excited vibration can be prevented or suppressed.

[0058] In this embodiment, the tool holding hole 301c is shown as a through hole connecting the inner circumferential surface 142 of the workpiece insertion hole 141 and the outer circumferential surface 143 of the tool holder 14c. However, the tool holding hole 301c is not limited to such a through hole. For example, the tool holding hole 301c may be a bottomed hole extending from the inner circumferential surface 142 of the workpiece insertion hole 141 toward the outer circumferential surface 143 of the tool holder 14c. In short, the tool holding hole 301c only needs to allow insertion of the tool 20c in such a manner that the cutting edge portion 201c of the tool 20c protrudes from the inner circumferential surface 142 of the workpiece insertion hole 141 toward the second axis A2.

[0059] Here, the method for positioning the cutting edge portion 201c will be described. Figure 7 is a diagram illustrating the positioning jig 40 for the tool 20c and the method for positioning the tool 20c. As shown in Figure 7, the positioning jig 40 is equipped with a first contact surface 41 and a second contact surface 42. Both the first contact surface 41 and the second contact surface 42 are flat and are spaced a predetermined distance apart in the normal direction. The first contact surface 41 is brought into contact with the end face of the tool holder 14c on the side closer to the chuck 11 and perpendicular to the second axis A2 (the surface corresponding to the top surface of the frustocone), and in that state, the tool 20c is brought into contact with the second contact surface 42. In that state, the tool 20c is fixed to the tool holder 14c by tightening the screw 31.

[0060] Thus, the positioning jig 40 is configured to define the "projection dimension of the cutting edge portion 201c of the tool 20c in the direction of the second axis A2 from the end face of the tool holder 14c" by bringing the first contact surface 41 into contact with the end face of the tool holder 14c and the second contact surface 42 into contact with the tool 20c. If the dimensions and shape of the cutting edge portion 201c after grinding are the same as before grinding (and in an unworn state), then by using such a positioning jig 40, the distance of the cutting edge portion 201c from the second axis A2 can be made the same before and after grinding. Furthermore, with such a positioning jig 40, it is not necessary to bring the jig into contact with the tip of the cutting edge portion 201c (the point closest to the second axis A2) when positioning the tool 20c. Therefore, wear and tear caused by the jig coming into contact with the tip of the cutting edge portion 201c during positioning can be prevented.

[0061] The distance between the first contact surface 41 and the second contact surface 42 of the positioning jig 40 is set appropriately according to the dimensions and shape of the cutting edge portion 201c of the tool 20c used and the diameter of the bottom surface of the helical groove formed in the workpiece W (i.e., the distance from the second axis A2 to the cutting edge portion 201c). For this reason, a positioning jig 40 is prepared for each tool 20c used and each product manufactured.

[0062] Although embodiments of the present invention have been described above, the technical scope of the present invention is not limited to these embodiments. The present invention can be modified without departing from its spirit, and such modifications are also included within the technical scope of the present invention. [Explanation of Symbols]

[0063] 10a, 10b, 10c...Waring device, 11...Chuck, 14a, 14b, 14c...Tool holder, 20a, 20b, 20c...Tool, 30a, 30b, 30c...Tool holding portion of tool holder, 141...Workpiece insertion hole of tool holder, 144...Tapered portion of tool holder, 201a, 201b, 201c...Cutting edge portion of tool, 301a, 301c...Tool holding hole of tool holding portion, W...Workpiece, A1...First axis, A2...Second axis

Claims

1. A chuck that can rotate a rod-shaped workpiece around a first axis, The tool holder comprises a plurality of tool holding parts configured to hold tools having cutting edges, and the plurality of tools held in the plurality of tool holding parts can be rotated about a second axis that is twisted with respect to the first axis, One end of the second axis of the tool holder, the end closer to the chuck, is provided with a substantially frustoconical tapered portion whose outer diameter decreases as it approaches the chuck, with the second axis as the center. In a view perpendicular to the second axis, the angle η between the second axis and the surface of the tapered portion is given by the following formula (1): Waring device. 90° > η ≥ 80° - θ Formula (1) θ: The angle between the first axis and the projected second axis when the second axis is projected onto a plane that includes the first axis and is parallel to the second axis.

2. The Waring device according to Claim 1, The tool holder is provided with a workpiece insertion hole that allows the workpiece to be loosely inserted, is coaxial with the second axis, and penetrates the center of the tapered portion. The tool holding portion is provided on the surface of the tapered portion so as to be able to hold the tool such that the cutting edge portion protrudes towards the inner circumference of the workpiece insertion hole. Waring device.

3. A Waring device according to Claim 1, The tool has a rod-like structure with the cutting edge portion provided at one end in the longitudinal direction. The tool holder is configured to hold the tool in a orientation in which the cutting edge is located closer to the second axis, and to hold the tool in a manner that allows for changes in its radial position on a circle centered on the second axis. Waring device.

4. The Waring device according to Claim 3, The tool holder is provided with a workpiece insertion hole that allows the workpiece to be loosely inserted and is coaxial with the second axis, The tool holding portion includes a tool holding hole into which the tool can be inserted, and which extends from the inner circumferential surface of the workpiece insertion hole in a direction that is inclined at the same angle η as the angle η between the second axis and the surface of the tapered portion with respect to the second axis. Waring device.

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