Tool body

A tool body to which a replaceable cutting insert is fixed includes: a holder: an insert mounting seat that is provided on a first surface of the holder; a clamp member that constrains the cutting insert placed on the insert mounting seat; and an operating member that presses a pressure receiving surface of the clamp member. The clamp member has the pressure receiving surface, a spherical head portion that is formed into a spherical crown shape, and a hook portion that protrudes to a side opposite to a side of the spherical head portion when seen from a side of the first surface. The insert mounting seat supports the clamp member to be swingable with the spherical head portion as a fulcrum, and the hook portion contacts a diameter reducing portion that is formed on an inner peripheral surface of an mounting hole for the cutting insert in a state in which the pressure receiving surface is pressed.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application relates to and claims priority from Japanese Patent Application No. 2021-003700, filed on Jan. 13, 2021, the entire disclosure of which is incorporated herein by reference.

BACKGROUND

Field

The present invention relates to a tool body to which a replaceable cutting insert is fixed.

Description of Related Art

A turning tool includes a replaceable cutting insert and a tool body to which the cutting insert is fixed. The cutting insert is fixed to the insert mounting seat of a tool body by a cramp screw or the like inserted from one end surface to the other end surface. In a state in which the turning tool is attached to a tool rest such as a turret, a worker sometimes has a difficulty in extracting the cramp screw in a direction facing the insert mounting seat. Therefore, there has been proposed a tool body that allows the operation of a cramp member in a direction different from a direction in which an insert mounting seat is provided.

For example, Japanese Translation of PCT Application No. 2012-514543 discloses a cutting insert fixation device in which fastening or loosening of an L-shaped clamp lever is allowed by the rotation of a fixation screw arranged on a surface different from a surface on which an insert pocket is provided. The axial line of the fixation screw obliquely crosses the insert pocket. When the fixation screw is fastened, the distal end of the fixation screw presses an inclined surface provided on the clamp lever and the clamp lever turns with the lower end of a supporting portion formed into a cylindrical surface as a fulcrum.

SUMMARY

However, in the cutting insert fixation device described in Japanese Translation of PCT Application No. 2012-514543, a direction in which the fixation screw is allowed to press the clamp lever is limited to the axial line direction of the fixation screw. In Japanese Translation of PCT Application No. 2012-514543, an inclined surface inclined with respect to the bottom surface of the clamp lever serves as a pressure receiving surface perpendicular to the axial line direction of the fixation screw. Thus, it is possible to transmit, even if a direction in which the fixation screw presses the clamp lever is deviated from a direction in which the clamp lever turns, the pressing force of the fixation screw to the clamp lever so long as the deviation is only a certain degree of deviation. However, in such a configuration, it is not possible to arrange the fixation screw so as to be greatly deviated with respect to the direction in which the clamp lever turns.

In a case in which a turning tool is attached to a turret, the position most easily operated by a worker could be the distal end surface of the turning tool. In a configuration as disclosed in Japanese Translation of PCT Application No. 2012-514543, it is difficult to arrange an operating member on the distal end surface of a turning tool since limitation on the arrangement of a fixation screw is large. In addition, in a configuration as disclosed in Japanese Translation of PCT Application No. 2012-514543, the lower end of the column surface of a supporting portion that supports a load from a fixation screw is rounded and the position of a fulcrum becomes unstable as a clamp lever repeatedly swings. The accuracy of a position at which the clamp lever contacts a cutting insert is susceptible to uneven abrasion.

The present invention has been made in view of the above circumstances and has an object of providing a tool body that facilitates the replacement of a cutting insert.

An aspect of the present invention provides a tool body to which a replaceable cutting insert is fixed, the tool body including: a holder: an insert mounting seat that is provided on a first surface of the holder; a clamp member that constrains the cutting insert placed on the insert mounting seat; and an operating member that presses a pressure receiving surface of the clamp member. The clamp member has the pressure receiving surface, a spherical head portion that is formed into a spherical crown shape, and a hook portion that protrudes to a side opposite to a side of the spherical head portion when seen from a side of the first surface. The insert mounting seat supports the clamp member to be swingable with the spherical head portion as a fulcrum, and the hook portion contacts a diameter reducing portion that is formed on an inner peripheral surface of an mounting hole for the cutting insert in a state in which the pressure receiving surface is pressed.

According to the aspect, the clamp member is capable of freely swinging vertically and horizontally with the spherical-crown-shaped spherical head portion as a fulcrum. Therefore, it is possible to press the cutting insert with the hook portion in a deviated positional relationship in which the clamp member is not on the same plane as the input direction of the operating member. It is possible to arrange the operating member at an optimum position at which the replacement of the cutting insert is facilitated. Since the spherical head portion serving as a fulcrum is originally a spherical surface, influence on the positional accuracy between the clamp member and the insert mounting seat is small even if the spherical head portion is rounded due to its abrasion.

In the aspect, the operating member may have a screw portion on which a male screw threadedly engaged with the holder is formed and a pressing surface that presses the pressure receiving surface in a direction crossing an axial line of the screw portion.

According to the aspect, it is possible to make a direction in which the operating member moves different from a direction in which the pressing surface of the operating member presses the pressure receiving surface of the clamp member when the screw portion of the operating member is fastened. By a synergistic effect with the spherical-crown-shaped spherical head portion having a large degree of freedom in movement, it is possible to achieve not only a positional relationship in which the axial line direction of the screw portion of the operating member is deviated from the turning direction of the clamp member but also a further increase in the deviating amounts of the directions compared with a configuration in which the spherical head portion is not provided. As a result, it is possible to reduce limitation on the arrangement of the operating member.

In the aspect, the pressure receiving surface may be constituted by a part of a recessed cylindrical surface, and the pressing surface may be constituted by a track formed by rotating a protruding arc serving as a generating line about the axial line of the screw portion on an outer peripheral side of the screw portion.

According to the aspect, the position of a force point is easily arranged in a narrow region as designed since the contact area between the pressing surface and the pressure receiving surface is small. As a result, it is possible to more reliably constrain the cutting insert.

In the aspect, the holder may have a distal end surface that faces a side opposite to a side on which the tool body is fixed to a working machine, and at least a part of the operating member may be exposed to a side of the distal end surface.

According to the aspect, it is possible to arrange the operating member on the distal end surface since limitation on the arrangement of the operating member is small. Since a worker is allowed to perform an operation on the side of the distal end surface of the tool body, the replacement of the cutting insert is facilitated in a case in which a turning tool is attached to a tool rest such as a turret.

In the aspect, the hook portion may have a central portion and first and second end portions that are positioned on sides opposite to each other with the central portion held therebetween, and the first and second end portions may contact the cutting insert while the central portion does not contact the cutting insert.

The shape of the distal end of the hook portion or the shape of the mounting hole for the cutting insert has a slight fluctuation allowed as tolerance. According to the aspect, the hook portion reliably contacts the inner peripheral surface of the diameter reducing portion at two points even if the shape of the hook portion or the shape of the attachment surface has a slight fluctuation. Therefore, the constraint of the cutting insert by the clamp member becomes stable.

According to the present invention, it is possible to provide a tool body that facilitates the replacement of a cutting insert.

DETAILED DESCRIPTION

A preferred embodiment of the present invention will be described with reference to the accompanying drawings. Note that parts denoted by the same symbols have the same or similar configurations in respective figures. Hereinafter, respective configurations will be described in detail with reference to the drawings.FIG.1is a perspective view showing an example of a turning tool1according to an embodiment of the present invention. As shown inFIG.1, the turning tool1includes a replaceable cutting insert2and a tool body3to which the cutting insert2is fixed. In an example shown inFIG.1, the turning tool1is configured as a grooving tool fixed to the tool rest of a lathe.

The tool body3includes a holder4and a clamp member6and an operating member7that are attached to the holder4. The holder4is formed into a rod shape extending from a proximal end41E to a distal end42E on the side opposite to the side of the proximal end41E. At a distal end42of the holder4that includes the distal end42E and its adjacent parts, an insert mounting seat5on which the cutting insert2is to be placed is provided. The side of the holder4that is closer to the proximal end41E than the distal end42is configured as a shank fixable to a working machine.

FIG.2is an exploded perspective view of the turning tool1shown inFIG.1. As shown inFIG.2, the insert mounting seat5has a seating surface52that contacts the bottom surface (for example, a second end surface22) of the cutting insert2that will be described later to constrain the cutting insert2and a wall surface53that contacts a peripheral lateral surface23of the cutting insert2that will be described later to constrain the cutting insert2.

The distal end42has a distal end surface425and first to fourth surfaces421,422,423, and424facing the distal end surface425. The distal end42E of the holder4is positioned on the distal end surface425. The insert mounting seat5is provided on the first surface421. The second surface422is positioned on the side opposite to the side of the first surface421. The third and fourth surfaces423and424connect the first and second surfaces421and422to each other.

In the following description, a direction from the first surface421to the second surface422and a direction from the second surface422to the first surface421in a height direction Dh of the holder4are called a downward direction and an upward direction, respectively, in some cases. The height direction (vertical direction) Dh of the holder4is a direction in which the first surface421and the second surface422of the distal end42are connected to each other and may not be necessarily orthogonal to a longitudinal direction DL of the holder4in which the proximal end41E and the distal end42E of the holder4are connected to each other.

The operating member7has a screw portion71formed into a cylindrical shape and a pressing surface72connected to the screw portion71. A male screw is formed on the outer peripheral surface of the screw portion71and threadedly engaged with the female screw of a through-hole47formed on the holder4. In an example shown inFIG.2, the through-hole47is formed to be exposed to the side of the distal end surface425through the distal end surface425of the holder4, and an axial line X of the male screw of the operating member7and the through-hole47of the holder4is formed to be parallel to the longitudinal direction DL of the holder4.

The cutting insert2has a first end surface21, the second end surface22on the side opposite to the side of the first end surface21, the peripheral lateral surface23that connects the first end surface21and the second end surface22to each other, and an mounting hole29that penetrates the first end surface21and the second end surface22. The peripheral lateral surface23includes cutting blades24that cut off an object to be cut and rake faces25and flanks26that face the cutting blades24.

At least a part of the second end surface22is configured as a bottom surface supported by the seating surface52of the insert mounting seat5. In the example shown inFIG.2, the first end surface21and the second end surface22have substantially the same shape. Therefore, it is possible to attach the cutting insert2to the insert mounting seat5with the first end surface21serving as a bottom surface by inverting the cutting insert2upside down.

In the example shown inFIG.2, the peripheral lateral surface23is formed symmetrically at 180° with respect to a central axis Z of the mounting hole29. The peripheral lateral surface23includes the totally four cutting blades24of two blades24usable when the cutting insert2is attached to the insert mounting seat5with the second end surface22serving as a bottom surface and two cutting blades24usable when the cutting insert2is attached to the insert mounting seat5with the first end surface21serving as a bottom surface.

FIG.3is a plan view of the distal end42shown inFIG.1when seen from the side of the first surface421. The clamp member6turns along a IV-IV line on the symmetrical surface of the clamp member6and constrains the cutting insert2placed on the insert mounting seat5. As shown inFIG.3, a direction in which the axial line X of the screw portion71extends is greatly deviated from the symmetrical surface of the clamp member6including the IV-IV line.

FIG.4is a cross-sectional view along the IV-IV line inFIG.3and shows the symmetrical surface of the clamp member6. As shown inFIG.4, the inner peripheral surface of an mounting hole29for the cutting insert2has a large diameter portion291and a diameter reducing portion292having an inner diameter smaller than that of the large diameter portion291. In an example shown inFIG.4, the large diameter portion291is formed on each of the first end surface21and the second end surface22, and the diameter reducing portion292is formed on the intermediate portion between the first end surface21and the second end surface22.

The clamp member6has a spherical head portion62, a pressure receiving surface67, and a hook portion61. The spherical head portion62is formed into a spherical crown shape (seeFIG.2). On the insert mounting seat5, a recessed spherical surface562following the shape of the spherical head portion62is formed. Since the spherical head portion62slidingly contacts the recessed spherical surface562, the insert mounting seat5supports the clamp member6to be swingable with the spherical head portion62as a fulcrum. As shown inFIG.4, the hook portion61contacts the diameter reducing portion292of the cutting insert2in a state in which the pressure receiving surface67is pressed by the operating member7.

FIG.5is a perspective view showing the clamp member6and the operating member7that are shown inFIG.4. The pressing surface72described above is capable of pressing the pressure receiving surface67in a direction crossing the axial line X of the screw portion71. The operating member7may further have an apex surface73capable of pressing the pressure receiving surface67in a direction parallel to the axial line X. The apex surface73is arranged so as to cross the axial line X, and the pressing surface72is arranged so as not to cross the axial line X. The pressing surface72is formed so that its distance from the axial line X reduces as its distance from the screw portion71increases. In an example shown inFIG.5, the pressing surface72is constituted by a track formed by rotating a protruding arc serving as a generating line about the axial line X on the outer peripheral side of the screw portion71.

FIG.6is a perspective view showing the pressure receiving surface67from which the operating member7shown inFIG.5is removed. In an example shown inFIG.6, the pressure receiving surface67is constituted by a part of recessed cylindrical surfaces671and672. The boundary between the recessed cylindrical surfaces671and672may be a ridge line. The pressure receiving surface67may further include a band-shaped curvature surface673that connects the gap between the recessed cylindrical surfaces671and672.

FIG.7is a perspective view of the clamp member6shown inFIG.5when seen from the side of the spherical head portion62. The spherical head portion62is formed into a spherical crown shape as described above and formed into a substantially semi-spherical shape in an example shown inFIG.7. In the example shown inFIG.7, the clamp member6is formed into a curved shape and includes first and second cylindrical portions601and602extending parallel to each other and a connecting portion603that connects the lower end of the first cylindrical portion601and the upper end of the second cylindrical portion602to each other.

The hook portion61is provided at the upper end of the first cylindrical portion601. The pressure receiving surface67is provided between the upper end and the lower end of the second cylindrical portion602. The spherical head portion62is provided at the upper end of the second cylindrical portion602. At the upper end of the second cylindrical portion602, the connecting portion603protrudes to the side opposite to the side of the spherical head portion62.

FIG.8is a plan view of the clamp member6shown inFIG.5when seen from the side of the first surface421of the distal end42of the holder4. As shown inFIG.8, the hook portion61protrudes to the side opposite to the side of the spherical head portion62when seen from the side of the first surface421, that is, when seen from above. The distal end of the hook portion61has a central portion613and first and second end portions611and612positioned on sides opposite to each other with the central portion613held therebetween.

The central portion613of the hook portion61does not contact the cutting insert2, while the first and second end portions611and612of the hook portion61are formed to be angulated so that the first and second end portions (both end portions)611and612contact the diameter reducing portion292of the cutting insert. More specifically, the outer shape of the distal end of the hook portion61when seen from the side of the first surface421is formed so that the central portion613held between the first and second end portions611and612has an arc shape having a greater radius of the circle of curvature than that of the first cylindrical portion601, and so that each of the first and second end portions611and612has an arc shape having a smaller radius of the curvature of circle than that of the first cylindrical portion601.

A description will be given again with reference toFIG.4. As shown inFIG.4, a part (the upper half of the first cylindrical portion601) of the clamp member6is positioned on a side closer to the first surface421than the bottom surface (the second end surface22in the example shown inFIG.4) of the cutting insert2in a state in which the clamp member6constrains the cutting insert2. The remaining parts (the lower half of the first cylindrical portion601, the second cylindrical portion602, and the connecting portion603) of the clamp member6are positioned on a side closer to the second surface422than the bottom surface of the cutting insert2.

The insert mounting seat5is provided with a pocket56that accommodates the remaining parts (buried parts) of the clamp member6that are buried on a side closer to the inner side (the side of the second surface422) of the tool body3than the bottom surface of the cutting insert2. The pocket56is formed into a substantially L-shape including a space extending parallel to the seating surface52and a space extending perpendicular to the seating surface. The recessed spherical surface562described above is provided at the corner portion of the substantially L-shaped pocket56.

According to the tool body3of the present embodiment configured as described above, the clamp member6is capable of freely swinging vertically and horizontally with the spherical-crown-shaped spherical head portion62as a fulcrum. Since the spherical head portion62is supported by the recessed spherical surface562as shown inFIG.4, the positional relationship between the clamp member6and the insert mounting seat5is not likely to change even if a sliding contact surface is rounded due to its abrasion.

As shown inFIG.5, it is possible to make a direction in which the operating member7moves different from a direction in which the pressing surface72of the operating member7presses the pressure receiving surface67of the clamp member6. Therefore, by a synergistic effect with the spherical-crown-shaped spherical head portion62having a large degree of freedom in movement, it is possible to reduce limitation on the arrangement of the operating member7. As shown inFIG.1, it is also possible to arrange the operating member7on the distal end surface425. Therefore, a worker is allowed to easily replace the cutting insert2in a case in which the turning tool1is attached to a tool rest such as a turret.

The embodiment described above aims to facilitate the understanding of the present invention and does not intend to limit the interpretation of the present invention. The respective elements and their arrangements, materials, conditions, shapes, sizes, or the like provided in the embodiment are not limited to illustrated ones but are appropriately modifiable. Further, it is also possible to partially replace or combine configurations shown in different embodiments with each other.