SHANK AND CUTTING TOOL HAVING THE SHANK

The present invention can realize better cutting performance while suppressing an influence of, for instance, deflection of a head and an increase in a moment acting on a fastening mechanism even when a cutting insert of a long total length is used. A shank of a head replaceable type cutting tool includes: a fastening mechanism that is formed at a leading end part in a longitudinal direction of the shank, and attaches a head; and a recessed part that is formed at the leading end part so as to accommodate a part of a cutting insert held by the head and avoid an interference with the cutting insert. The recessed part may be provided to accommodate a non-use part of the cutting insert held by the head in a state where the head is attached to the leading end part, and avoid an interference with the cutting insert.

BACKGROUND

Field

The present invention relates to a shank and a cutting tool including this shank.

Description of Related Art

Regarding a head replaceable type cutting tool adopting a structure in which a head that holds an insert is removably fastened to a leading end part of a shank, there are proposed a technique related to a structure for detaching a head in a state where a shank is attached to a machine tool such as a blade rest, and a technique related to a mechanism of fastening a head and a shank. Furthermore, for a head replaceable type cutting tool, there is conventionally proposed a technique that has been conceived from a viewpoint of improvement of operability for enabling quick replacement of a cutting insert, and realization of cost reduction by measuring a blade tip position in a state, where a cutting insert is dismounted from a machine tool, and reducing an arrangement time (see, for example, Patent Publications JP 2020-28943A, JP 2020-533188A, JP 2014-524357A, and JP 2012-522651A).

Furthermore, a cutting tool may be used in a scene that a cutting insert (chip) having a long total length is required, hence there is also proposed a technique related to a structure or the like for holding such a cutting insert (see Patent Publications JP 2007-203379A and JP H06-155110A).

SUMMARY

However, conventional head replaceable type cutting tools do not assume fastening a cutting insert having a longer total chip length (that is, for example, in a case of a cutting insert having a pair of cutting edges, a length from a leading end of one cutting edge to a leading end of another cutting edge) than a difference (referred to as a “projection amount of a head from a shank” below) between a total head length and a length of a fastening mechanism (an attachment/detachment pin for attaching and detaching the head to and from the shank) in a longitudinal direction of the shank. Generally, in a case of a small cutting tool or the like having a small width, if a fastening mechanism cannot be shifted in a direction apart from an insert, the insert and the fastening mechanism interfere with each other. In this regard, the conventional techniques have had no option but to increase an effective head length as a method for separating a fastening mechanism and a cutting insert so as not to interfere with each other. In other words, in a case where a cutting insert of a long total chip length is used as described, the conventional cutting tools have had no option but to set a longer projection amount of a head from a shank than the total length of the cutting insert. However, the conventional head replaceable type cutting tools each employ a configuration where only the shank contacts the blade rest, and the fastening mechanism alone accepts a force applied to the head, and therefore an increase in the projection amount of the head from the shank increases a distance between a cutting point and the fastening mechanism, and the force applied to the fastening mechanism influences cutting performance, which significantly affect the cutting performance.

It is therefore an object of the present invention to provide a shank and a cutting tool including the shank that are able to realize better cutting performance while suppressing an influence of, for instance, deflection of a head and an increase in a moment acting on a fastening mechanism even when a cutting insert of a long total length is used.

An aspect of the present invention is a shank of a head replaceable type cutting tool that includes: a fastening mechanism that is formed at a leading end part in a longitudinal direction of the shank, the fastening mechanism is configured to attach a head; and a recessed part that is formed at the leading end part so as to accommodate a part of a cutting insert held by the head and avoid an interference with the cutting insert.

According to the above shank, it is possible to attach to the shank the head to which the cutting insert having a longer total chip length than a projection amount of the head from the shank (i.e., a difference between a total head length and a length of the fastening mechanism in the longitudinal direction of the shank) has been attached. That is, although part of a cutting edge of a cutting insert held by such a head conventionally interferes with a fastening mechanism and a shank, the shank according to this aspect can avoid occurrence of an interference by accommodating part of such a cutting insert in the recessed part. Consequently, although a projection amount of the head from the shank conventionally needs to be set longer than a total length of the cutting insert, it is possible to attach the head to the shank without making such settings according to this aspect. Thus, since the head can be attached to the shank without increasing the projection amount of the head from the shank, it is not necessary to increase a distance between a cutting point and the fastening mechanism, so that, even when the cutting insert of the long total length is used, it is possible to suppress an influence due to deflection of the head and an increase in a moment acting on the fastening mechanism.

The above shank has a generally cuboid shape of which lateral cross-sectional shape perpendicular to the longitudinal direction of the shank is a rectangular shape, the fastening mechanism may be provided at the leading end part in the longitudinal direction of the shank, the fastening mechanism being a mechanism for attaching and detaching the head, and including an attachment/detachment operation part capable of performing an operation of attaching or detaching the head in a direction substantially perpendicular to the longitudinal direction, and the recessed part may be provided having a shape on a first reference face, the shape being recessed from the first reference face with a difference in height that is smaller than a width of the first reference face and has a value larger than 10% of the width of the first reference face, and the first reference face being on an opposite side to an operation face, which is provided with the attachment/detachment operation part, among side surfaces of the shank.

According to the above shank, the recessed part may be provided so as to accommodate a non-use part of the cutting insert held by the head in a state where the head is attached to the leading end part, and avoid an interference with the cutting insert.

According to the above shank, a side surface, which is provided with the operation face, among the side surfaces of the shank may have a stepped shape, and a stepped part that forms the stepped shape may be provided closer to a base end part along the longitudinal direction than a stepped part formed between the first reference face and the recessed part.

According to the above shank, the operation face may be a plane that continuously extends over a total length of the shank.

According to the above shank, an interval between the operation face and the first reference face may be larger than the width of the first reference face.

According to the above shank, a head attachment/detachment hole of the fastening mechanism for attaching and detaching the head may be offset and disposed in a direction farther from the recessed part than from a central axis of the shank extending in the longitudinal direction.

According to the above shank, a rib may be formed at the recessed part.

According to the above shank, the rib may be formed on one of both sides of the recessed part in a width direction of the first reference face.

According to the above shank, the rib may be formed on both sides of the recessed part in a width direction of the first reference face.

A cutting tool according to an aspect of the present invention includes the above shank.

DETAILED DESCRIPTION

A preferred embodiment of a shank10and a head replaceable type cutting tool (also referred to simply as a cutting tool below)1including this shank10according to the present invention will be described in detail below with reference to the drawings (see, for example,FIG.1).

First Embodiment

The head replaceable type cutting tool1is configured as a tool for cutting into a workpiece (not illustrated) by feeding a cutting edge52of a cutting insert50at a time of machining using an automatic lathe (not illustrated) or the like. In this regard, the automatic lathe that automatically performs lathe work turns a workpiece by moving the cutting tool1along a direction (an axis perpendicular to a Z axis is conveniently referred to as an X axis in the present embodiment) perpendicular to the cutting tool1while feeding the long workpiece in a predetermined direction (that is a Z axis direction in the present embodiment), and cuts out a three-dimensional shape (seeFIGS.1and2). Furthermore, a plurality of types of the heat replaceable type cutting tools1are disposed as a “gang type” on a blade rest200, the blade rest200is moved in an X axis direction or a Y axis direction perpendicular to both of the X axis direction and the Z axis direction according to a mode of lathe turning, and the cutting insert50is appropriately selected, moved and replaced to perform predetermined machining (seeFIGS.1and2).

The cutting tool1according to the present embodiment used for such lathe turning is a head replaceable type cutting tool that enables attachment and detachment of a head20to and from the shank10, and include these shank10and head20, and, in addition, a fastening mechanism30for attaching the head20to the shank10(see, for example,FIG.7).

The shank10is formed so as to be attached to the blade rest200in a state where a grip target part (a main body part whose lateral cross section is uniform in the shank10according to the present embodiment)10hof the shank is gripped (see, for example,FIGS.1to3). In an example, the shank10according to the present embodiment has a generally cuboid shape whose lateral cross-sectional shape perpendicular to a longitudinal direction (a direction that matches with the above-described X axis direction) along a central axis10X (see, for example,FIG.6B) of the shank10is a rectangular shape (see, for example,FIGS.6A to6C).

Hereinafter, for ease of description, four side surfaces of the shank10are respectively defined as follows in the present embodiment. First, a face seen from a direction denoted by symbol B inFIG.3is a “first reference face”, and is denoted by reference numeral11(see, for example,FIGS.3and6B). This first reference face11is a face that functions as a reference face (attachment face) for positioning the shank10in a Z direction when the shank10is attached to the blade rest200(seeFIGS.1and2). A width (also referred to as a shank height) of the first reference face11is denoted by symbol SH (see, for example,FIGS.3and6B). Furthermore, a face seen from a direction denoted by symbol A inFIG.3is a “fourth face”, and is denoted by reference numeral14(see, for example,FIGS.3to6B). A face on an opposite side to this fourth face14is a “second reference face”, and is denoted by reference numeral12(see, for example,FIG.6B). This second reference face12functions as a reference face (attachment face) for positioning the shank10in a Y direction when the shank10is attached to the blade rest200(seeFIGS.1and2). Furthermore, a face on an opposite side to the first reference face11is denoted by reference numeral13as a “third side surface”, and, in a case where the third side surface13includes a stepped part13D, a face of the third side surface13provided with a screw hole13bfor a fastening screw40in particular is referred to as an “operation face”, and is denoted by reference numeral13S (see, for example,FIG.6A). The operation face13S allows an operation for attaching and detaching the head20by turning the fastening screw40from the operation face13S side (seeFIGS.8and9. The screw hole13bconstitutes part of an attachment/detachment operation part32of the fastening mechanism30for attaching and detaching the head20to and from the shank10.

At a leading end part10tof the shank10, an attachment part15and a recessed part16are formed (see, for example,FIG.3). The attachment part15is a part to which the head20is attached using the fastening mechanism30. The attachment part15is provided with a head attachment/detachment hole31in which an attachment/detachment pin21of the head20can be inserted (see, for example,FIG.3). Furthermore, the attachment part15is provided with a projected part15tthat uniquely defines a direction of the head20when the projected part15tfits to a predetermined recessed part (not illustrated) of the head20to be attached (see, for example,FIGS.3and6A).

The recessed part16is formed at the leading end part10tof the shank10so as to accommodate part of the cutting insert50held by the head20, and avoid an interference with the cutting insert50(see, for example,FIG.4). For example, the recessed part16of the head replaceable type cutting tool1according to the present embodiment that uses the cutting insert50including the pair of cutting edges52is provided to accommodate a non-use part (that is a side including the cutting edge52that is not used for cutting) of the cutting insert50held by the head20in a state where the head20is attached to the leading end part10tof the shank10, and avoid the interference with the cutting insert (see, for example,FIGS.4and9). The recessed part16according to the present embodiment is formed by a stepped part11D (a size of a height in difference of the stepped part11D is denoted by symbol DH inFIG.6A) by cutting out part on the first reference face11side of the shank10(seeFIG.6A). Although the shape of the recessed part16and the difference in height DH of the stepped part11D are not limited in particular, the recessed part16is formed in the present embodiment such that the recessed part16has a shape that is recessed from the first reference face11with the difference in height DH that is smaller than the width (shank width) SH of the first reference face11and takes a value larger than 10% of the width (shank width) SW of the first reference face11(see, for example,FIG.6A). That is, the difference in height DH is appropriately set by taking into account that the difference in height DH preferably has a size (depth) that can accommodate an entire width of the cutting insert50, yet there is a case where the difference in height DH can accommodate only part of the width of the cutting insert50in a case where the difference in height DH is 10% of the width SW or less, and, on the other hand, it is concerned that too large a DH value is excessive for a purpose of accommodating the cutting insert50, and rigidity of the shank10lowers.

Furthermore, the shank10has a stepped shape in which the stepped part13D is provided to the third side surface13as described above (see, for example,FIG.6A). Although a position of the stepped part13D in the longitudinal direction (a direction along the central axis10X) of the shank10is not limited in particular, for example, the stepped part13D is provided closer to a base end part10balong the longitudinal direction than the stepped part11D formed between the first reference face11and the recessed part16in the present embodiment (see, for example,6A). While the shank10according to the present embodiment has a crank shape near the leading end part10tseen from the second reference face12or the fourth face14(see, for example,FIG.6A), the step13D is provided at the above-described position, and consequently a width in the middle of the crank shape part does not narrow too much, so that it is possible to form the predetermined crank shape near the leading end part10twhile securing the required rigidity of the shank10.

The head20is a member that is formed removably from the leading end part10tof the shank10. The head20according to the present embodiment is formed as a member that includes the attachment/detachment pin21, an insert mounting seat22, and a retainer part23(see, for example,FIG.7). The attachment/detachment pin21is a pin having a length LP that can be inserted in the head attachment/detachment hole31of the shank10(seeFIG.9), and is fixed by retaining a side part of the attachment/detachment pin21by the fastening screw40in a state where the attachment/detachment pin21is inserted in the head attachment/detachment hole31. The insert mounting seat22is a base for mounting the cutting insert50with a mounting screw54, and is provided to a side part of the head20that faces the first reference face11side of the shank10(see, for example,FIGS.7and9). The cutting insert50including the pair of cutting edges52can be mounted on this insert mounting seat22. The retainer part23is provided near the insert mounting seat22to retain the cutting insert50(see, for example,FIG.7). A projection amount HE of the head20from the shank10in the head replaceable type cutting tool1according to the present embodiment is a length along an axial direction from a leading end face of the attachment part15of the shank10to a leading end pat of the retainer part23, in other words, a length (HE=LH−LP) obtained by subtracting a length LP of the attachment/detachment pin21from a total length LH of the head20(seeFIG.9). Note that the cutting insert50can be replaced with various types, and therefore description related to the head20is made herein.

The fastening mechanism30is a mechanism for attaching the head20to the leading end part10tof the shank10, and includes, for example, the attachment/detachment pin21of the head20, the head attachment/detachment hole31, the attachment/detachment operation part32, and the like. The head attachment/detachment hole31is provided at the attachment part15at the leading end part10tof the shank10such that the attachment/detachment pin21of the head20can be inserted in the head attachment/detachment hole31(see, for example,FIG.3). The attachment/detachment operation part32is a part for performing an operation to attach and detach the head20, and, more specifically, includes the screw hole13band the fastening screw40to be screwed to the screw hole13b(see, for example,FIG.7). According to the head replaceable type cutting tool1according to the present embodiment, it is possible to attach and detach the head20by performing an operation of screwing or unscrewing the fastening screw40in a substantially perpendicular direction to the longitudinal direction (the direction of the central axis10X) of the shank10. Note that a position of the head attachment/detachment hole31is not limited in particular, and may be disposed at a position matching with the central axis10X of the shank10or may be disposed at a position displaced therefrom. In the present embodiment, the head attachment/detachment hole31is disposed at a position offset in a direction (in other words, a direction to approach the operation face13S) farther from the recessed part16than from the central axis10X (see, for example,FIG.8). In a case where the head attachment/detachment hole31is offset in this way, there is a pad at a part near the recessed part16at the leading end part10tof the shank10, so that it is easy to avoid an event that formation of the recessed part16forms a thin thickness part.

The above head replaceable type cutting tool1can be used as a structure (assembly) that includes the shank10, the head20, and the fastening mechanism30for attaching the head20to the shank10. Upon actual use, the shank10is fixed to the blade rest200such as a gang type by a jig, the head20is fixed to the shank10using the fastening mechanism30, the cutting insert50is mounted on the insert mounting seat22of the head20, and then the cutting edge52is caused to cut into a rotating workpiece (cutting target member) to cut (see, for example,FIGS.1and2).

According to this head replaceable type cutting tool1and the shank10that constitutes the head replaceable type cutting tool1, the total tip length (that is the length along the central axis10X of the shank10from the leading end of the one cutting edge52to the leading end of the other cutting edge52in a case of the cutting insert50including the pair of cutting edges52as in the present embodiment, and is denoted by symbol LC inFIG.9) can suppress deflection of the head20and an increase in a moment acting on the fastening mechanism30even when the relatively long cutting insert50is used, and realize better cutting performance. In a case where, for example, the cutting insert50of the long total tip length LC is used, simply increasing a total head length to meet the total tip length LC as in the conventional techniques, and providing to the head a recessed part for accommodating a non-use part of a cutting edge increase a projection amount of the head from a shank, and a length from a fastening mechanism to a cutting point (cutting edge52) increases accompanying this increase, and, as a result, deflection of the head and a moment acting on the fastening mechanism increase, which may influence cutting performance (seeFIG.14. Note that part of corresponding reference numerals inFIG.14are illustrated by assigning dashes (′) thereto). In this regard, the head replaceable type cutting tool1according to the present embodiment, and the shank10of the head replaceable type cutting tool1employ a configuration where the recessed part16is provided to the shank10instead of the head20, so that it is possible to avoid occurrence of an interference by accommodating part of the cutting insert50in this recessed part16. Consequently, while the conventional techniques have had no option but to set a longer projection amount in a shank longitudinal direction of the head from the shank than the total length of the cutting insert, according to the present embodiment, it is possible to attach the head20to the shank10without making such settings, in other words, it is possible to attach the head20to the shank10without increasing the projection amount HE along the shank longitudinal direction of the head20from the shank10. This means that it is not necessary to increase a distance between the cutting point and the fastening mechanism30, so that, even when the cutting insert50of the long total length is used, it is possible to suppress an influence due to deflection of the head20and an increase in a moment acting on the fastening mechanism30. By reducing deflection of the head20or the like and a load on the fastening mechanism30, it is also possible to make performance related to rigidity of the head replaceable type cutting tool1and the like closer to performance of a cutting tool of an integral type (that is not the head replaceable type, and is formed by a uniform metal member including a tip fastening part).

Second Embodiment

According to the head replaceable type cutting tool1according to the present embodiment, the operation face13S of the shank10is formed by the plane that continuously extends over the total length of the shank10, and the entire operation face13S formed by this plane is formed as namely the third side surface13(see virtual lines illustrated inFIGS.5and6A). In other words, the shank10according to the present embodiment has a shape that is not provided with the stepped part (13D) on the third side surface. Furthermore, in the shank10according to the present embodiment, the interval (also referred to as the shank width) SW between the operation face13S (third side surface13) and the first reference face11is larger than the width (shank height) SH of the first reference face11(seeFIGS.6A and6B). When the third side surface13is the above plane, a cross-sectional area of the shank10increases, so that rigidity improves. On a side note, in a case where the third side surface13is the above plane, the third side surface13may be a positioning reference face in the Z axis direction (seeFIGS.1and2) in place of the first reference face11.

Third Embodiment

The shape of the recessed part16of the shank10of the head replaceable type cutting tool1may adopt various shapes and modes based on the tip shape (the shape of the cutting edge52) of the cutting insert50. Another aspect example of the recessed part16at which a rib18is formed will be described below as a third embodiment below (seeFIGS.10to12).

Under a condition that the cutting edge52on the non-use side of the cutting insert50does not cause an interference, the rib18may be formed at the recessed part16. The rib18may be formed on both sides in a width direction (that is, in other words, a direction of the shank height SH and matches with the Y axis direction in a case where the shank10is attached to the blade rest200) of the first reference face11(seeFIG.10), or may be formed only on one of the both sides (seeFIGS.11and12).

Note that the above-described embodiment is a preferred embodiment of the present embodiment, yet is not limited to this, and can be variously modified and carried out without departing from the spirit of the present invention.

The present invention is suitably applied to a shank for a cutting tool, or a head replaceable type cutting tool including the shank.