EP1992463A2

EP1992463A2 - Rotational cutting tool

Info

Publication number: EP1992463A2
Application number: EP08008615A
Authority: EP
Inventors: Makoto Ogasawara
Original assignee: Kanefusa KK; Kanefusa Corp
Current assignee: Kanefusa KK; Kanefusa Corp
Priority date: 2007-05-18
Filing date: 2008-05-07
Publication date: 2008-11-19
Also published as: CN101306541A; JP2008284791A; EP1992463A3

Abstract

A rotational cutting tool 10 includes a plurality of unit cutting tools 11A to 11C including rotational bodies 12A to 12C each in a cylindrical shape and formed with attachment grooves 25 twisted relative to an axial direction and extending between opposite ends at plural locations in a circumferential direction on an outer peripheral surface of the rotational body, and flat plate-like replaceable blades 31 slidably mounted to the attachment grooves 25, the unit cutting tools 11A to 11C coaxially overlapped to one another in such a manner that the attachment grooves 25 of the unit cutting tools adjacent to each other are not overlapped to each other in the direction along which the attachment grooves 25 are extending. Between opposite ends in an axial direction on an outer peripheral surface of at least one of a pair of the unit cutting tools adjacent to each other, replacement grooves 51 that are capable of receiving the replaceable blades 31 are formed as extensions from the attachment grooves 25 of the other unit cutting tool.

Description

FIELD OF THE INVENTION

The present invention relates to a blade-replaceable type rotational cutting tool for use in processing woods, wood-based materials, plastics, metals, and the like. More specifically, the present invention relates to a rotational cutting tool equipped with replaceable blades at positions twisted relative to a rotational main shaft of a rotational driving device.

BACKGROUND ART

Conventionally, a rotational cutting tool of this type is disclosed in Japanese Patent No. 2515196 . This cutting tool includes: a rotational body in a cylindrical shape and formed with attachment grooves twisted relative to the axial direction at plural locations in the circumferential direction on the outer peripheral surface of the rotational body; and plate-like replaceable blades mounted to the attachment grooves so as to be slidable along the attachment grooves. By disposing the replaceable blades in the direction twisted relative to the axial direction of the rotational body, there is an effect that the cutting resistance and cutting noises during a cutting operation can be reduced, and further, the smoothness on the cut surface can be enhanced. This rotational cutting tool has a structure in which, in order to enhance the easiness and the attachment accuracy in mounting the replaceable blades to the attachment grooves, each blade is formed with a groove extending in the longitudinal direction. Then, a convex portion formed on a blade body pressing metal and extending in the longitudinal direction of the attachment groove is fitted to the groove. As a result, the replaceable blades are mounted to the rotational body in a state where a centrifugal force involved in the rotation prevents the replaceable blades from coming off outward. For this reason, in replacing any replaceable blade, the fixed state of the replaceable blade fixed by the centrifugal force is released, and the replaceable blade is slid along the attachment groove. Thus, the replaceable blade is detached from the side surface of the rotational body.
However, according to the prior art described above, if the rotational body has a long length in order to enable wide-range cutting in one cutting operation, it is inevitably required to decrease the twisted angle of the plate-like replaceable blade. In this case, it is impossible to achieve an effect of reducing the cutting resistance and cutting noises during the cutting operation and enhancing the smoothness of the cut surface. Contrary to the above, if the twisted angle of the replaceable blade is set to be large, the rotational body is required to have a short length. In this case, it is impossible to satisfy a demand for enabling wide-range cutting in one cutting operation.
The present invention has been made to solve the problems described above, and an objective of the invention is to provide a rotational cutting tool in which replaceable blades are mounted to attachment grooves formed on a rotational body at positions twisted relative to the axial direction, thereby reducing the cutting noises and enhancing the smoothness of the cut surface, and also facilitating the replacement of the replaceable blades.

DISCLOSURE OF THE INVENTION

In order to achieve the obj ective described above, the present invention is structurally characterized in a rotational cutting tool, comprising a plurality of unit cutting tools each including: a rotational body in a cylindrical shape and formed with attachment grooves twisted relative to an axial direction and extending between opposite ends at plural locations in a circumferential direction on an outer peripheral surface of the rotational body; and flat plate-like replaceable blades mounted to the attachment grooves, the unit cutting tools coaxially overlapped to one another and disposed in such a manner that the attachment grooves of the unit cutting tools adjacent to each other are not overlapped to each other in the direction along which the attachment grooves are extending, wherein, between opposite ends in an axial direction on an outer peripheral surface of at least one of a pair of the unit cutting tools adjacent to each other, replacement grooves that are capable of receiving the replaceable blades are formed as extensions from the attachment grooves formed on the other unit cutting tool.
In the invention structured as described above, the rotational cutting tool is comprised of a plurality of unit cutting tools coaxially overlapped to one another. Owing to this structure, even if the axial lengths of the unit cutting tools are short, the overall length of the rotational cutting tool as a whole can be long. As a result, in the present invention, even by use of flat plate-like replaceable blades that is short in length, it is possible to design the attachment grooves of each unit cutting tool to assume a largely twisted posture. Thus, even the rotational cutting tool that is long in total length can reduce the cutting resistance and cutting noises during a cutting operation, and at the same time, the smoothness of the cut surface can be enhanced. Further, a plurality of unit cutting tools is overlapped to one another in the axial direction so as to form the rotational cutting tool. By changing the number of the unit cutting tools in accordance with the size of the area to be cut in one cutting operation, the overall length of the cutting tool can be freely adjusted. Further, as the length of the replaceable blades becomes shorter, the replaceable blades can be manufactured more easily and can be provided at lower price. Thus, even if a plurality of replaceable blades is employed in the rotational cutting tool that is long in length, the price of the replaceable blades can be relatively lowered as compared with the case in which one piece of replaceable blade that is long in length is employed.
Further, in the present invention, between opposite ends in an axial direction on an outer peripheral surface of at least one of a pair of the unit cutting tools adjacent to each other, replacement grooves that are capable of receiving the replaceable blades are formed as extensions from the attachment grooves formed on the other unit cutting tool. Thus, in replacing any replaceable blade, replacement of the replaceable blade can be performed with the rotational cutting tool kept mounted to the rotational main shaft of the rotational driving device, without the need of detaching the unit cutting tools each time the replaceable blade is replaced. Specifically, the replaceable blade is slid along the attachment groove so as to be moved into the replacement groove that is continuous to the attachment groove. In this manner, the replaceable blade can be detached easily and radially outward in the replacement groove. As a result, in the present invention, the labor required for replacement of the replaceable blade is significantly reduced because there is no need to detach the unit cutting tools each time the replaceable blade is replaced.
Further, in the present invention, the end portions in the axial direction of the rotational body may be protruding portions that is slightly protruding in the axial direction in a predetermined range in the circumferential direction that are the opposite sides of each attachment groove, and a section between the protruding portions is a recessed portion that is relatively recessed. Thereby, the adjacent unit cutting tools can be overlapped to one another by engaging the protruding portions and the recessed portions. In this manner, since the end portions of the cutting edges of the adjacent unit cutting tools can be overlapped at the end portions in the axial direction, the continuity of the cutting operation can be ensured.
Further, in the present invention, the end portions of the replaceable blade may be formed with a cutting edge in such a manner that a cutting radius thereof becomes slightly smaller than that of the other portions. In this manner, the replaceable blades of the adjacent unit cutting tools can be connected to each other with a smooth boundary, and a trouble that unnecessary lines are created on the surface of the material to be cut can be avoided.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a perspective view showing a rotational cutting tool as an embodiment of the present invention.
Fig. 2 is a front view showing the rotational cutting tool.
Fig. 3 is a front view showing a reference cutting tool that constitutes the rotational cutting tool.
Fig. 4 is a left side view showing the reference cutting tool that constitutes the rotational cutting tool.
Fig. 5 is a right side view showing the reference cutting tool that constitutes the rotational cutting tool.
Fig. 6 is a perspective view showing the reference cutting tool that constitutes the rotational cutting tool seen from its left side.
Fig. 7 is a perspective view showing the reference cutting tool that constitutes the rotational cutting tool seen from its right side.
Fig. 8 is an enlarged front view showing an attachment groove of the rotational cutting tool in detail.
Fig. 9 is a front view showing a replaceable blade mounted to the attachment groove of the rotational cutting tool in detail.
Fig. 10 is a rear view showing the replaceable blade.
Fig. 11 is a plan view showing the replaceable blade.
Fig. 12 is a cross-sectional view showing the replaceable blade along the line M-M in Fig. 9.
Fig. 13 is a perspective view showing the replaceable blade.
Fig. 14 is a front view showing an intermediate cutting tool that constitutes the rotational cutting tool.
Fig. 15 is a left side view showing the intermediate cutting tool.
Fig. 16 is a right side view showing the intermediate cutting tool.
Fig. 17 is a perspective view showing the intermediate cutting tool seen from the left side.
Fig. 18 is a perspective view showing the intermediate cutting tool seen from the right side.
Fig. 19 is a front view showing the other end-side cutting tool that constitutes the rotational cutting tool.
Fig. 20 is a left side view showing the other end-side cutting tool.
Fig. 21 is a right side view showing the other end-side cutting tool.
Fig. 22 is a perspective view showing the other end-side cutting tool seen from the left side.
Fig. 23 is a perspective view showing the other end-side cutting tool seen from the right side.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described using the drawings. Figs. 1 and 2 show a rotational cutting tool according to the embodiment by way of a perspective view and a front view, respectively. Figs. 3 to 7 show a unit cutting tool that is to be a reference at one end side that constitutes the rotational cutting tool (hereinafter, referred to as a reference cutting tool) by way of a front view, a left side view, a right side view, a perspective view seen from the left side, and a perspective view seen from the right side, respectively, and Fig. 8 shows a portion where a replaceable blade of the unit cutting tool is attached, by way of an enlarged side view. Figs. 9 to 13 show the replaceable blade by way of a front view, a plan view, a perspective view, and a cross-sectional view, respectively. Figs. 14 to 18 show a unit cutting tool located at an intermediate position (hereinafter, referred to as an intermediate cutting tool) by way of a front view, a left side view, a right side view, a perspective view seen from the left side, and a perspective view seen from the right side, respectively. Figs. 19 to 23 show a unit cutting tool located at the other end side (hereinafter, referred to as the other end-side cutting tool) by way of a front view, a left side view, a right side view, a perspective view seen from the left side, and a perspective view seen from the right side, respectively.
A rotational cutting tool 10 is comprised of three different kinds of unit cutting tools, that is, a reference cutting tool 11A, two intermediate cutting tools 11B, and the other end-side cutting tool 11C, which are coaxially and sequentially overlapped to one another. The reference cutting tool 11A includes a rotational body 12A in the shape of cylinder and having a center axial hole 13. The rotational body 12A is formed with three attachment grooves 25 on its outer periphery at three locations at equal intervals in the circumferential direction. Each attachment groove 25 is radially recessed to enable attachment of a replaceable blade 31 twisted at an inclined angle of substantially 30° relative to the axial direction. Further, one end surface 14 in the axial direction of the rotational body 12A is a flat surface (at the left side in Fig. 3), and is formed with a circular ring-shaped boss portion 15 slightly protruding from the end surface in the vicinity of the area surrounding the axial hole 13.
A stopper plate 16 that is a ring-shaped thin plate is rotatably fitted to the boss portion 15. The outer diameter of the stopper plate 16 is set so that it extends beyond the positions of later-described bottom walls 28 of the attachment grooves 25. In this manner, the stopper plate 16 serves to prevent slippage of a replaceable blade 31, a clamping plate 36, and a centrifugal wedge 41 attached to each attachment groove 25, which are described later, from the rotational body 12A. On the outer periphery of the stopper plate 16, recesses 17 each notched into a circular arc shape are formed at three locations at equal intervals in the circumferential direction. Each recess 17 is recessed beyond the bottom wall 28 of the attachment groove 25 toward the axial center so as not to become a hindrance when the replaceable blade 31 is inserted into the attachment groove 25 from the side of one end surface 14 of the rotational body 12A. Further, a press plate 18 is overlapped to the stopper plate 16. The press plate 18 is a plate in a circular ring shape and is smaller in outer diameter than the recesses 17. The stopper plate 16 is rotatable about the axial center with the press plate 18 overlapped thereon. By securing the press plate 18 with a bolt 19, the stopper plate 16 and the press plate 18 are integrally fixed to the rotational body 12A.
Further, the other end surface 21 of the rotational body 12A in the axial direction (at the right side in Fig. 3) is a flat surface, and is formed with a boss portion 22 in a circular ring shape that protrudes slightly around the axial hole 13. Further, on the other end surface 21, fan-shaped protruding portions 23 are provided. The fan-shaped protruding portions 23 reside in the range at the center angle 60° on opposite sides of each of the three attachment grooves 25 in the circumferential direction and in the region between the position slightly apart from the boss portion 22 in the radial direction and the outer peripheral edge. The height of the protrusion of each protruding portion 23 is slightly larger than that of the boss portion 22. The gap between the protruding portions 23 is a fan-shaped portion 24 relatively recessed lower than the protruding portion 23.
As shown in Fig. 8, each attachment groove 25 is generally in a square shape in cross section taken along the axial direction at a right angle, and includes a first side wall 26 and a second side wall 27 opposing to each other, and a bottom wall 28 that connects the first and second side walls 26, 27 to each other at the axial center side. The twisted angle of the attachment groove 25 relative to the axial direction of the rotational body 12A can be set to a large value up to about 45°. The first side wall 26 inclines toward the direction along which an opening 29 of the attachment groove 25 opened radially outward becomes narrow, and includes a contact surface 26a to be in contact with the replaceable blade 31, and a insertedly fitting recessed portion 26b which is recessed in the vicinity of the bottom wall 28 in the circumferential direction and into which a later-described fitting convex portion 39 of the clamping plate 36 is insertedly fitted. The second side wall 27 inclines toward the direction along which the opening 29 becomes narrow, and is to be in contact with an opposite surface 43 of a later-described centrifugal wedge 41. On the outer peripheral surface of the rotational body 12A, there are three replacement grooves 51 apart from the attachment grooves 25 at substantially 40° in the rotational direction and extending between the opposite ends of the rotational body 12A substantially in parallel to the attachment grooves 25. These grooves are for convenience of the groove processing, and are not used in replacement of the replaceable blades 31 in this embodiment. Therefore, these grooves may be omitted.
As shown in Figs. 9 to 13, the length of the replaceable blade 31 is equal to that of the attachment groove 25, and includes a pair of cutting edges 32 whose ridge lines at the opposite sides in the width direction mildly bulge outward in the width direction into the shape of a circular arc shape. Both cutting edges 32 can be used by changing the orientation of the replaceable blade 31. A relief surface 32a of the cutting edge 32 is formed by being polished into an inclined surface whose inclined angle smoothly and continuously varies in the longitudinal direction in such a manner that the relief angle becomes constant or nearly constant along the outer periphery of the rotational body 12A. At the front side of the replaceable blade 31, a pair of linear protrusions 33 extending between the opposite ends in the longitudinal direction along the cutting edge 32 is provided near each cutting edge 32. The outer edge in the width direction of each linear protrusion 33 assumes a curvature in a circular arc shape along the cutting edge 32, and the inner edge in the width direction thereof assumes a straight line, and the gap between the inner edges is a straight engagement groove 34. A back surface 35 of the replaceable blade 31 is a flat surface.
The clamping plate 36 is a rod-like member having the same length as the attachment groove 25, and is placed on the bottom wall 28. One surface 36a of the clamping plate 36 is closely attached to one side surface 42 of the centrifugal wedge 41, whereas the opposite surface 36b is in a rough shape. The clamping plate 36 includes an engagement convex portion 37, an intermediate convex portion 38, and a fitting convex portion 39 in this order from the side of the opening 29 of the attachment groove 25. In a state where the clamping plate 36 is pressed against the first side wall 26, the engagement convex portion 37 is fitted into the engagement groove 34 of the replaceable blade 31, the intermediate convex portion 38 is brought into contact with the first side wall 26, and the fitting convex portion 39 is fitted into the insertedly fitting recessed portion 26b. The centrifugal wedge 41 is a square rod-like member having the same length as the attachment groove 25. One side surface 42 thereof is closely attached to one surface 36a of the clamping plate 36, the opposite surface 43 thereof is closely attached to the second side wall 27 of the attachment groove 25, and the bottom surface 44 thereof is spaced from the bottom wall 28 of the attachment groove 25. The centrifugal wedge 41 is biased radially outward by a spring member 46 provided to the bottom wall 28.
The intermediate cutting tool 11B has a structure substantially identical to that of the reference cutting tool 11A, and includes a rotational body 12B formed with three attachment grooves 25 on its outer peripheral surface. The opposite end surfaces 14b, 21b in the axial direction of the rotational body 12B individually includes fan-shaped protruding portions 23 as is the case of the other end surface 21 of the reference cutting tool 11A. The fan-shaped protruding portions 23 protrude slightly in the range at the center angle 60° on opposite sides of each of the three attachment grooves 25 in the circumferential direction. On the outer peripheral surface of the rotational body 12B, there are three replacement grooves 51, which are apart from the attachment grooves 25 respectively at substantially 40° in the rotational direction and are extending between the opposite ends of the rotational body 12B substantially in parallel to the attachment grooves 25. The replacement grooves 51 are provided for use in replacement of the replaceable blades 31, and are grooves each in a circular arc shape in cross section. Each replacement groove 51 has a peripheral width and a radial depth capable of accommodating the replaceable blade 31, and is designed so that its width and depth continuously reduce from one end toward the other end in the axial direction. In addition, there are also three extended replacement grooves 52 slightly extended from one end in the axial direction substantially in parallel to the attachment groove 25 and spaced at substantially 40° in the reversal rotational direction relative to each attachment groove 25.
The other end-side cutting tool 11C includes a rotational body 12C having a structure identical to that of the reference cutting tool 11A. On one end surface 14c thereof in the axial direction, fan-shaped protrusions 23 are provided as is the case of the other end surface of the reference cutting tool 11A. The fan-shaped protruding portions 23 protrude slightly in the range at the center angle 60° on opposite sides of each of three attachment grooves 25 in the circumferential direction. As is the case of the one end surface of the reference cutting tool 11A, a stopper plate 16 and a press plate 18 are attached to the other end surface 21c in the axial direction. Further, the rotational body 12C is formed with three replacement grooves 51 extending between the opposite ends thereof substantially in parallel to the attachment grooves 25 and apart from each attachment groove 25 substantially at 40° in the rotational direction, as is the case of the intermediate cutting tool 11B . In addition, there are three extended replacement grooves 52 as three auxiliary grooves slightly extended from one end substantially in parallel to the attachment grooves 25 and spaced at substantially 40° in the reversal rotational direction relative to each attachment groove 25.
In assembly to complete the rotational cutting tool 10, the other end of the reference cutting tool 11A and one end of the intermediate cutting tool 11B are fitted with their protruding portion 23 and their recessed portion 24 mated with each other, so that the reference cutting tool 11A and the intermediate cutting tool 11B are connected in a state where they are aligned to each other. Further, the intermediate cutting tools 11B are connected to each other, and the other end-side cutting tool 11C is connected to the second intermediate cutting tool 11B, thereby completing a rotational cutting tool 10. A connection shaft member 55 is insertedly fitted through the axial hole 13 of the rotational cutting tool 10 to tighten four unit cutting tools 11A to 11C from the opposite ends in order to prevent them from detaching from each other. In mounting the rotational cutting tool 10 to the rotational driving device (not shown), the reference cutting tool 11A is located at the side of the rotational driving device, and the axial hole 13 is insertedly fitted to the rotational main shaft of the rotational driving device. By rotating the rotational cutting tool 10 in a state where it is mounted to the rotational main shaft of the rotational driving device, the centrifugal wedge 41 mounted to the attachment groove 25 is subjected to the centrifugal force of rotation to shift radially outward, and is fixed with its opposite surfaces entrapped between the clamping plate 36 and the second side wall 27 of the attachment groove 25. According to this, upon receiving a pressing force from the side surface of the centrifugal wedge 41, the replacement plate 31 is firmly fixed to the attachment groove 25 in a state where the replacement plate 31 is pressed and is positioned against the first side wall 26 of the attachment groove 25 via the clamping plate 36. As a result, in this embodiment, the replaceable blade 31 can be easily and accurately mounted to the attachment groove 25.
In the embodiment structured as described above, the rotational cutting tool 10 is comprised of a plurality of unit cutting tools 11A to 11C coaxially overlapped to one another. Owing to this structure, even if the axial lengths of the unit cutting tools 11A to 11C are short, the total length of the tool 10 as a whole can be long. As a result, according to this embodiment, even by use of flat plate-like replaceable blades 31 short in length, it is possible to design the attachment grooves 25 to assume a largely twisted posture. Thus, even the rotational cutting tool 10 long in total length can reduce the cutting resistance and cutting noises during a cutting operation, and at the same time, can enhance the smoothness of the cut surface. Further, a plurality of unit cutting tools 11A to 11C is overlapped to one another in the axial direction to form the rotational cutting tool 10. Therefore, by changing the number of the unit cutting tools 11A to 11C in accordance with the size of the area to be cut in one cutting operation, the length of the cutting tool 10 can be freely adjusted. Further, when the attachment grooves 25 are designed to assume a largely twisted posture, as the length of the replaceable blades 31 becomes shorter, the replaceable blades 31 can be manufactured more easily and can be provided at lower price. Thus, even if a plurality of replaceable blades 31 is employed in the rotational cutting tool 10 long in length, the price of the replaceable blades can be relatively lowered as compared with the case where one piece of replaceable blade long in length is employed.
Further, in this embodiment, the intermediate cutting tools 11B and the other end-side cutting tool 11C, except for the reference cutting tool 11A disposed at one end side of the rotational cutting tool 10 in the axial direction, are formed with replacement grooves 51 on their outer peripheral surfaces. The replacement grooves 51 extend from the attachment grooves 25 of the adjacent unit cutting tool, and are capable of receiving the replaceable blades 31. In this manner, in replacing any replaceable blade 31, replacement of the replaceable blade 31 can be performed with the rotational cutting tool 10 kept mounted to the rotational main shaft of the rotational driving device, without the need of detaching the unit cutting tools 11A to 11C each time the replaceable blade 31 is replaced. Specifically, the fixed state of the replaceable blade 31 to the attachment groove 25 by a centrifugal force exerted by the centrifugal wedge 41 is released, and the replaceable blade 31 is slid along the attachment groove 25 to be moved into the replacement groove 51 continuous to the attachment groove 25. In this manner, the replaceable blade 31 can be detached easily and radially outward in the replacement groove 51. As a result, in this embodiment, the labor required for replacement of the replaceable blade 31 is significantly reduced.
Further, in this embodiment, the end portions of the rotational bodies 12A to 12C in the axial direction include protruding portions 23 slightly protruding in the axial direction in a predetermined range in the circumferential direction on the opposite sides of each attachment groove 25. The section between the protruding portions 23 is a recessed portion 24 that is relatively recessed. Thereby, the adjacent unit cutting tools 11A to 11C can be combined and overlapped to one another by combining the protruding portions 23 and the recessed portions 24. In this manner, since the end portions of the replaceable blades 31 of the adjacent unit cutting tools can be overlapped at the end portions in the axial direction, the continuity of the cutting operation can be ensured. Further, in this embodiment, the cutting edge 32 of the replaceable blade 31 is formed into a circular arc shape bulging outward in the width direction between the opposite ends in the longitudinal direction. The cutting radius of the end portions of the replaceable blade 31 is designed to be slightly smaller than those of the remaining portions. In this manner, the replaceable blades 31 of the adjacent unit cutting tools can be connected to each other with a smooth boundary, and a trouble that unnecessary lines appear on the surface of the material to be cut can be avoided.
In the above embodiment, the intermediate cutting tools and the other end-side cutting tool are respectively formed with the replacement grooves as extensions from the attachment grooves of the unit cutting tool adjacent thereto at one end side in the axial direction (toward an end portion of the reference cutting tool). Alternatively, the reference cutting tool and the intermediate cutting tools may be respectively formed with replacement grooves as extensions from the attachment grooves of the unit cutting tool adjacent thereto at the other end side in the axial direction (toward an end portion of the other end-side cutting tool). Still alternatively, it is also possible to form replacement grooves as extensions fromboth sides of the attachment grooves described above. Further, in the embodiment described above, the rotational cutting tool includes four unit cutting tools connected to each other; however, the structure thereof is not limited thereto.
Alternatively, two or more unit cutting tools that are necessary may be selected and connected to each other. Further, the number of the attachment grooves formed on each unit cutting tool is not limited to three, but may be an arbitrary number that is two or greater. The rotational cutting tool in the embodiment above has been demonstrated for the purpose of exemplification, and various modifications may be made thereto without departing from the gist of the present invention.

INDUSTRIAL APPLICABILITY

According to the present invention, the rotational cutting tool is formed by coaxially combining a plurality of unit cutting tools. Even if its total length is designed to be long, the cutting resistance and cutting noises during a cutting operation can be reduced, and the smoothness on the cut surface can be enhanced. Further, replacement grooves are formed on the unit cutting tools other than the unit cutting tool as a reference cutting tool, in replacing any replaceable blade, replacement of the replaceable blade can be performed with the rotational cutting tool kept mounted to the rotational main shaft of the rotational driving device, without the need of detaching the unit cutting tools each time the replaceable blade is replaced. Thereby, the labor required for replacement of the replaceable blade is significantly reduced. Thus, the present invention is useful.

Claims

A rotational cutting tool, comprising a plurality of unit cutting tools each including: a rotational body in a cylindrical shape and formed with attachment grooves twisted relative to an axial direction and extending between opposite ends at plural locations in a circumferential direction on an outer peripheral surface of the rotational body; and flat plate-like replaceable blades mounted to said attachment grooves, said unit cutting tools coaxially overlapped to one another and disposed in such a manner that said attachment grooves of said unit cutting tools adjacent to each other are not overlapped in the direction along which said attachment grooves are extending, wherein, between opposite ends in an axial direction on an outer peripheral surface of at least one of a pair of said unit cutting tools adj acent to each other, replacement grooves that are capable of receiving said replaceable blades are formed as extensions from said attachment grooves formed on the other unit cutting tool.
A rotational cutting tool according to claim 1, wherein the end portions in the axial direction of said rotational body are protruding portions slightly protruding in the axial direction in a predetermined range in the circumferential direction on opposite sides of each attachment groove, and a section between the protruding portions is a recessed portion that is relatively recessed.
A rotational cutting tool according to claim 2, wherein the end portions of said replaceable blade is formed with a cutting edge in such a manner that a cutting radius thereof becomes slightly smaller than the other portions of the replaceable blade.