JP7290206B1 - Cutting tools - Google Patents

Abstract

A cutting tool capable of ensuring sufficient body rigidity while enabling small-diameter drilling. A cutting tool (10) includes a body (100) formed with a discharge groove (120) for guiding and discharging chips, and a cutting insert (200) fastened and fixed to the tip side of the body (100). The cutting insert 200 has a first surface 210 with a through hole 230 and a main cutting edge 231 formed to extend linearly at the end of the first surface 210 . The body 100 is formed with a protruding portion 130 that protrudes so as to cover a portion of the first surface 210 of the cutting insert 200 from the outside. The blade 231 extends from the outer peripheral side of the body 100 to a position straddling the central axis AX1 of the body 100 . [Selection drawing] Fig. 2

Description

The present invention relates to cutting tools.

Cutting tools capable of both turning and drilling are known, for example, the cutting tool described in Patent Document 1 below. This cutting tool includes a body in which a discharge groove for guiding and discharging chips is formed, and a cutting insert fastened and fixed to the tip side of the body.

JP 2019-155559 A

In order to enable drilling, the cutting edge provided on the cutting insert needs to have a length approximately equal to the radius of the hole formed in the drilling. Specifically, when viewed along the central axis of the body, the cutting edge must extend outward from at least the central axis to a position that is about the radius of the hole.

By the way, in a cutting tool used for drilling a small diameter hole, the size of the cutting insert becomes smaller as the cutting edge becomes shorter. However, if the size of the cutting insert becomes too small, it becomes difficult to ensure strength enough to withstand fastening and fixing to the body. Therefore, it is conceivable to attach a cutting insert having a cutting edge longer than the radius of the hole to the body. In this case, when viewed along the central axis of the body, the cutting edge extends from the outer peripheral side of the body to a position straddling the central axis of the body, and only a portion thereof is used for cutting.

However, in such a configuration, a portion of the body that holds the cutting insert becomes too thin, which may cause a problem of reduced rigidity of the body.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cutting tool capable of ensuring sufficient body rigidity while enabling small-diameter drilling.

A cutting tool according to the present invention comprises a body formed so that a discharge groove for guiding and discharging chips extends from the tip side to the base end side, and a cutting insert fastened and fixed to the tip side of the body. , provided. The cutting insert has a first surface having a through hole for inserting the fastening member, a second surface opposite to the first surface and in contact with the insert seat of the body, and a first surface. a main cutting edge formed so as to extend linearly at the end of the surface, at least a part of which is used for cutting, the first surface facing the inside of the discharge groove, and the main cutting edge extending from the body; It is fastened and fixed to the body by a fastening member so as to protrude further to the tip side than the tip of the. The body is formed with a protruding portion that protrudes so as to cover a part of the first surface of the cutting insert from the outside. When viewed along the central axis of the body, the main cutting edge extends from the outer peripheral side of the body to a position straddling the central axis of the body.

In the cutting tool configured as described above, the main cutting edge provided on the cutting insert extends from the outer peripheral side of the body to a position straddling the central axis of the body. That is, the length of the main cutting edge is longer than the radius of the hole. In such a configuration, there is a concern that the vicinity of the portion of the body where the cutting insert is provided becomes thin as the size of the cutting insert increases, and the rigidity of the body decreases.

Therefore, in the body of the cutting tool configured as described above, a projecting portion projecting from the inner surface of the discharge groove is formed so as to cover a part of the first surface of the cutting insert from the outside. Since the body becomes thicker due to the presence of the protrusion, the rigidity of the body does not decrease excessively as the size of the cutting insert increases.

As a further preferred embodiment, the projecting portion may overlap neither the main cutting edge nor the through hole when viewed along the central axis of the through hole.

As a further preferred embodiment, the cutting insert includes a first corner cutting edge connected to the outer peripheral edge of the main cutting edge, and a second corner located on the opposite side of the first corner cutting edge along the diagonal line of the first surface. and a cutting edge, wherein the second corner cutting edge may be covered by the protrusion.

As a further preferred embodiment, the body may be formed with a recess hole for preventing contact with the second corner cutting edge.

As a further preferred embodiment, the recess hole may be formed so as to extend from the surface of the body opposite to the projection toward the second corner cutting edge.

As a further preferred embodiment, the recessed hole may be formed as a blind hole that does not penetrate the protrusion.

ADVANTAGE OF THE INVENTION According to this invention, the cutting tool which can ensure the rigidity of a body sufficiently, while enabling a small diameter drilling process is provided.

FIG. 1 is a perspective view showing the configuration of a cutting tool according to this embodiment. 2 is an enlarged view of a part of the cutting tool shown in FIG. 1. FIG. FIG. 3 is a drawing of the cutting tool shown in FIG. 1 as viewed from a direction along the central axis of the body. FIG. 4 is a diagram showing the configuration of a cutting insert included in the cutting tool according to this embodiment. 5 is a diagram showing a state in which the cutting insert is removed from the body of the cutting tool shown in FIG. 2; FIG. FIG. 6 is a drawing of the cutting tool shown in FIG. 2 as viewed from a direction along the central axis of the through hole of the cutting insert. FIG. 7 is a diagram showing the configuration of a cutting tool according to a comparative example.

Hereinafter, this embodiment will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same constituent elements in each drawing are denoted by the same reference numerals as much as possible, and overlapping descriptions are omitted.

The cutting tool 10 according to this embodiment is configured as a tool capable of both turning and drilling. Turning includes processing for increasing the inner diameter of an existing hole formed in a work material, processing of the end surface (bottom surface) of the hole, and the like. Drilling is a process for forming a circular hole in a work material from scratch. A hole formed by drilling may be a bottomed hole or a through hole. In addition, such a configuration of the cutting tool 10 is merely an example. The cutting tool 10 may be configured as a tool for performing only one of turning and drilling. A cutting tool 10 comprises a body 100 and a cutting insert 200 .

The body 100 is a member that constitutes substantially the entire cutting tool 10 and is made of steel. The body 100 is a rod-like member having a substantially cylindrical shape, and a cutting insert 200, which will be described later, is attached to one tip side thereof. For convenience of explanation, hereinafter, the end side of the body 100 to which the cutting insert 200 is attached is also referred to as the "distal end side", and the opposite side is also referred to as the "base end side".

A discharge groove 120 is formed in the body 100 . The discharge groove 120 is a groove for guiding and discharging chips generated during machining of the work material toward the base end side. The discharge groove 120 is formed on the side surface of the body 100 so as to extend linearly from the position of the cutting insert 200 toward the base end. The discharge groove 120 is defined by a pair of flat surfaces 121 and 122 and a curved surface connecting them. The angle between flat surface 121 and flat surface 122 is preferably in the range of 70 degrees to 120 degrees, but may be outside this range.

1 is a straight line representing the central axis of the body 100. In FIG. Below, this central axis is also described as "central axis AX1". If the discharge groove 120 were not formed in the body 100, the cross section of the body 100 taken perpendicularly to its longitudinal direction would be circular. A central axis AX1 is an axis passing through the center of the circle. Note that the cross-sectional shape of the body 100 in the case where the discharge groove 120 is not formed may be a shape other than circular. The central axis AX1 in this case can be set as an axis passing through the center of gravity of the shape, for example.

A flat surface 110 is formed on the side surface of the base end portion of the body 100 . The base end portion including the flat surface 110 is a portion that is gripped and fixed by a machine tool (not shown) and is also called a "shank". The flat surface 110 extends from the proximal end of the body 100 to a position near the discharge groove 120 .

The cutting insert 200 is a member provided with a main cutting edge 231 and a corner cutting edge 241 for cutting, and is made of, for example, a hard material. The cutting insert 200 is fastened and fixed by a fastening member 20 to an insert seat (bottom surface 140 to be described later) provided on the tip side of the body 100 . The specific configuration of the insert seat and its vicinity in the body 100 will be described later.

As shown in FIGS. 2, 3 and 4, the cutting insert 200 has a first face 210, a second face 220, major cutting edges 231, 232 and corner cutting edges 241, 242. .

The first surface 210 faces the inside of the discharge groove 120 when the cutting insert 200 is attached to the body 100 . As shown in FIG. 1, the first surface 210 is substantially parallel to and substantially coplanar with the flat surface 121 of the discharge groove 120 . The first surface 210 can also be said to be a surface that defines a part of the discharge groove 120 together with the flat surface 121 . As shown in FIG. 4, the shape of the first surface 210 is substantially parallelogram.

One end of the through hole 230 is open in the first surface 210 . The through hole 230 is a circular through hole through which the fastening member 20 is inserted. The through hole 230 is provided so as to pass through the cutting insert 200 from the first surface 210 to the second surface 220 described below. Central axis AX2 of through hole 230 is perpendicular to first surface 210 .

The second surface 220 is a surface opposite to the first surface 210 and is a surface that abuts on the insert seat (bottom surface 140, see FIG. 2) of the body 100. As shown in FIG. The second surface 220 is a flat surface parallel to the first surface 210 . The shape of the second surface 220 is substantially parallelogram like the first surface 210 . However, the second surface 220 is smaller than the first surface 210 because the flank 201 and the like are inclined surfaces as will be described later.

The main cutting edges 231, 232 and the corner cutting edges 241, 242 are cutting edges used for cutting the work material. As shown in FIG. 4 , these are all provided at positions that are the ends on the outer peripheral side of the first surface 210 . However, as a result of the provision of the recesses 211 and 212, which will be described later, the height positions of the main cutting edge 231, the corner cutting edge 241, and the like in the first surface 210 are the top surface of the first surface 210 (in FIG. 210”) is different from the height position.

The main cutting edges 231, 241 are cutting edges mainly used for drilling. The main cutting edges 231 and 241 are formed so as to extend linearly along a pair of mutually opposing sides of the first surface 210 which is substantially a parallelogram. Only one of the main cutting edges 231 and 241 actually functions as a "cutting edge" during machining of the work material. Which of the main cutting edges 231 and 241 functions as the “cutting edge” changes depending on how the cutting insert 200 is attached to the body 100 . For example, in the attached state shown in FIG. 2 or the like, only the main cutting edge 231 arranged on the tip side functions as a "cutting edge".

As shown in FIG. 6, the cutting insert 200 is in a state in which the main cutting edge (the main cutting edge 231 in this example) that is used for machining protrudes further toward the tip side than the tip surface 101 of the body 100. It is fastened and fixed to the body 100 by the fastening member 20 so that.

The cutting insert 200 has a rotationally symmetrical shape so that the main cutting edges 231, 241 can be switched and used. Specifically, when the cutting insert 200 is rotated about the central axis AX2 by 180 degrees, the entire shape of the cutting insert 200 after rotation overlaps the shape of the cutting insert 200 before rotation.

The range in which the main cutting edge 231 is provided is the range from the position of point A shown in FIG. Since the range in which the main cutting edge 232 is provided is the range obtained by rotating the above range by 180 degrees around the central axis AX2, the illustration thereof is omitted. Although the range in which the main cutting edge 231 is provided is as described above, only a part of the main cutting edge 231 is actually used for cutting in many cases. For example, in drilling, when the central axis of the hole is aligned with the central axis AX1, only the area on the right side of the central axis AX1 in FIG. be. The same applies to the main cutting edge 232 .

The corner cutting edges 241 and 242 are cutting edges mainly used for turning, and both are arranged at corner portions of the first surface 210 . In the state where the cutting insert 200 is attached to the body 100 as shown in FIG. The corner cutting edge 242 is located on the opposite side of the corner cutting edge 241 along the diagonal line of the first surface 210 . The corner cutting edge 241 corresponds to the "first corner cutting edge" of this embodiment. The corner cutting edge 242 corresponds to the "second corner cutting edge" of this embodiment.

The corner cutting edges 241 and 242 are formed so as to partially extend in a curved shape along a pair of opposing corner portions of the substantially parallelogram first surface 210 . As with the main cutting edges 231, 241 described above, only one of the corner cutting edges 241, 242 actually functions as a "cutting edge" during machining. For example, in the attached state shown in FIG. 2 and the like, only the corner cutting edge 241 arranged at the tip side and the outer peripheral side functions as a "cutting edge".

The range in which the corner cutting edge 241 is provided is an arcuate range from the position of point B to the position of point C shown in FIG. Since the range in which the corner cutting edge 242 is provided is the range obtained by rotating the above range by 180 degrees around the central axis AX2, the illustration thereof is omitted. In addition, in this embodiment, the portion from the point C to the point D shown in FIG. 4 is also formed as a linear cutting edge.

Other configurations of the cutting insert 200 will be described. As shown in FIG. 4 , concave portions 211 functioning as chip breakers are formed on the first surface 210 at positions near the main cutting edge 231 and the corner cutting edge 241 . Similarly, recesses 212 functioning as chip breakers are formed at positions near the main cutting edge 232 and the corner cutting edge 242 on the first surface 210 .

The surfaces extending from each of the main cutting edges 231, 232 and the corner cutting edges 241, 242 to the second surface 220 are surfaces provided as so-called "flank surfaces". None of these are perpendicular to the second surface 220 and are inclined with respect to the second surface 220 . For example, the flank 201 arranged on the distal side in FIG. 2 is inclined with respect to the second surface 220 so as to go toward the proximal side as it goes from the first surface 210 to the second surface 220 side. That is, the flank surface 201 is inclined such that the intersection angle between the flank surface 201 and the first surface 210 is an acute internal angle, and the intersection angle between the flank surface 201 and the second surface 220 is an obtuse internal angle. are doing. Other flanks connected to the main cutting edge 232 and the corner cutting edges 241 and 242 are the same.

In both turning and drilling, machining is performed by bringing the cutting edge of the cutting tool 10 into contact with the work material while rotating the work material. At that time, the central axis of rotation of the work material is aligned with the central axis AX1 of the body 100 . Instead of such a mode, machining may be performed while rotating the cutting tool 10 around the central axis AX1.

As shown in FIG. 3, when the cutting tool 10 is viewed along the central axis AX1 of the body 100, the point A indicating the end of the main cutting edge 231 is positioned to the left of the central axis AX1 in FIG. be. That is, the main cutting edge 231 of this embodiment extends from the outer peripheral side of the body 100 (the right side in the example of FIG. 3) to a position straddling the central axis AX1.

As described above, when drilling is performed while rotating the work material or cutting tool 10 around the central axis AX1, drilling can be performed as long as the main cutting edge 231 extends at least to the position of the central axis AX1. It can be carried out.

Therefore, it is conceivable to reduce the size of the cutting insert 200 so that the main cutting edge 231 has the minimum required length (that is, the length about the radius of the hole). However, in a cutting tool for forming a small-diameter hole, when the cutting insert 200 is downsized as described above, the proportion of the through hole 230 in the first surface 210 becomes too large, and the body 100 It becomes difficult to secure the strength of the cutting insert 200 that can withstand fastening and fixing to the cutting insert 200 . Therefore, in the cutting tool 10 according to the present embodiment, the main cutting edge 231 is made longer than the radius of the hole, so that the cutting insert 200 is made larger than the minimum size required for drilling a small diameter hole. This ensures sufficient strength of the cutting insert 200 .

A specific configuration of the body 100 in the vicinity of the cutting insert 200 will be described. FIG. 5 shows a perspective view of the body 100 with the cutting insert 200 removed. As shown in the figure, a recess for fitting the cutting insert 200 is formed in the tip side portion of the body 100, and the bottom surface 140 of the recess is formed.
is part of the insert seat. The bottom surface 140 is a surface parallel to the flat surface 121 . The recess is defined by surfaces 150, 161, 162 and the like in addition to the bottom surface 140. As shown in FIG. One end of a through hole 141 is opened in the bottom surface 140 . The through hole 141 is a hole through which the fastening member 20 for fixing the cutting insert 200 is inserted. A female screw (not shown) for screwing with the fastening member 20 is formed on the inner surface of the through hole 141 .

The surface 150 forms an insert seat together with the bottom surface 140 and is parallel to the flat surface 122 . As shown in FIG. 3 and the like, the height dimension of the surface 150 (the vertical dimension in FIG. 3) is smaller than the height dimension of the cutting insert 200 . The surface 150 abuts the side surface of the cutting insert 200 only at the side 151 opposite to the bottom surface 140, and constrains the position of the cutting insert 200 in the horizontal direction in FIG.

The surfaces 161 and 162 are surfaces formed so as to extend upward in FIG. 3 from the proximal end of the bottom surface 140 . As shown in FIG. 5 , they intersect each other at an obtuse angle and the straight line that bounds them protrudes slightly towards the cutting insert 200 . The boundary between the surfaces 161 and 162 abuts the side surface of the cutting insert 200 only at a point 163 at the end opposite to the bottom surface 140, constraining the position of the cutting insert 200 in the direction of the central axis AX1. there is

As shown in FIGS. 3 and 5, etc., a protruding portion 130 is formed at the tip portion of the body 100 . The projecting portion 130 is a tip-side portion of the surfaces defining the discharge groove 120, and is provided so as to project toward the right side in FIG. As shown in FIG. 2 and the like, the tip surface 122A in the direction in which the protruding portion 130 protrudes is connected to the flat surface 122 on the base end side. As shown in FIG. 3, the tip surface 122A of the protruding portion 130 protrudes to a position closer to the center axis AX1 (right side in FIG. 3) than the surface 150 that restrains the cutting insert 200. As shown in FIG. As shown in FIG. 6, the surface 122A is inclined with respect to the central axis AX1 so as to approach the central axis AX1 toward the base end side. By inclining the surface 122A in this way, it is possible to smoothly guide chips generated by the main cutting edge 231 and the like to the discharge groove 120 on the base end side.

A concave portion 131 is formed between the surface 150 and the projecting portion 130 . The concave portion 131 is formed so as to recede toward the opposite side (left side in FIG. 3) of the central axis AX1. A portion of the cutting insert 200 is accommodated in the recess 131 .

A part of the first surface 210 of the cutting insert 200 is covered with the protrusion 130 from the outside (from the upper side in FIG. 3) by providing the protrusion 130 on the body 100 . As described above, the body 100 of the present embodiment is provided with the protruding portion 130 that protrudes so as to cover a part of the first surface 210 of the cutting insert 200 from the outside.

The effect of providing the projecting portion 130 on the body 100 will be described. As described above, in the cutting tool 10 according to this embodiment, by making the main cutting edge 231 longer than the radius of the hole, the cutting insert 200 can be made larger than the minimum size required for small-diameter drilling. , and the strength of the cutting insert 200 is ensured. In such a configuration, if the body 100 is not provided with the projecting portion 130, as in the comparative example shown in FIG. 7) is too thin, there is a possibility that the rigidity of the body 100 cannot be sufficiently ensured.

Therefore, in the cutting tool 10 according to the present embodiment, the protrusion 130 is provided on the body 100 to increase the thickness of the portion corresponding to the dimension L in FIG. As a result, the rigidity of the body 100 is sufficiently ensured while the relatively large cutting insert 200 is held.

The amount of protrusion of the protruding portion 130 can be appropriately set in consideration of the allowable deflection of the body 100 during processing. However, when the cutting tool 10 is viewed along the central axis AX2 of the through hole 230 as shown in FIG. Preferably, a protrusion amount of 130 is set. By configuring the protruding portion 130 so as not to overlap the main cutting edge 231, it is possible to prevent troubles in machining. In addition, since the protruding portion 130 does not overlap the through hole 230, it is possible to prevent the operation of fastening and fixing the cutting insert 200 from being hindered.

As previously mentioned, the cutting insert 200 has a pair of corner cutting edges 241,242. As shown in FIG. 6 , the corner cutting edge 242 which is not used for machining is entirely covered from the outside by the protrusion 130 . That is, when the cutting tool 10 is viewed along the central axis AX2 of the through-hole 230, the corner cutting edge 242 entirely overlaps the projection 130. As shown in FIG. Since the corner cutting edge 242 is covered with the through hole 230, it is difficult for chips during machining to reach the corner cutting edge 242. - 特許庁This prevents the corner cutting edge 242 from being scratched or damaged.

As shown in FIG. 5, the body 100 is formed with a recess hole 170. As shown in FIG. When the cutting tool 10 is viewed along the central axis AX2 of the through hole 230 as shown in FIG.

As shown in FIG. 3 , the recess hole 170 extends from the surface of the body 100 opposite to the projection 130 (the lower surface in FIG. 3 ) toward the corner cutting edge 242 and the projection 130 . formed. The recess hole 170 is formed as a blind hole that does not pass through the projecting portion 130 , and the position of its tip is higher than the corner cutting edge 242 of the cutting insert 200 . As a result, the corner cutting edge 242 of the cutting insert 200 is entirely arranged within the space of the recess hole 170 and is not in contact with the body 100 at all.

In such a configuration, the cutting insert 200 is not constrained at the corner cutting edge 242 . Therefore, it is possible to attach cutting inserts 200 having various shapes to the common body 100 while providing variation in the shape of the corner cutting edge 242 .

It should be noted that only the portion of the recess hole 170 that overlaps the cutting insert 200 can exhibit the function described above, that is, the function of preventing interference with the corner cutting edge 242 . The portion of the recess hole 170 that does not overlap with the cutting insert 200 can be said to be a useless cutout portion that was formed inevitably for convenience of processing, although it cannot exhibit its original function. As shown in FIG. 3, the position of the main cutting edge 231 needs to be the position of the central axis AX1, and as a result, the cutting insert 200 is in a position biased toward the lower side than the center of the body 100. are placed. For this reason, if the recessed hole 170 is formed from the projecting portion 130 side (upper side in FIG. 3), the above-mentioned useless lightening portion becomes large. Therefore, in the present embodiment, the blanking hole 170 is not formed from the protrusion 130 side (upper side in FIG. 3), but is formed from the surface opposite to the protrusion 130, so that the blanking hole 170 is wasted. The meatless part is kept to a minimum. This suppresses a decrease in rigidity of the body 100 .

As the cutting insert 200, one having only one main cutting edge 231 and one corner cutting edge 241 may be used. In this case, the interference can be prevented by devising the shape of the cutting insert 200 , so the body 100 does not have to be formed with the recess hole 170 .

The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples by those skilled in the art are also included in the scope of the present disclosure as long as they have the features of the present disclosure. Each element included in each specific example described above and its arrangement, conditions, shape, etc. are not limited to those illustrated and can be changed as appropriate. As long as there is no technical contradiction, the combination of the elements included in the specific examples described above can be changed as appropriate.

10: Cutting tool, 20: Fastening member, 100: Body, 120: Discharge groove, 130: Protruding part, 140: Bottom surface (insert seat), 170: Nusumi hole, 200: Cutting insert, 210: First surface, 220: Second surface, 230: through hole, 231, 232; main cutting edge, 241, 242: corner cutting edge, AX1, AX2: central axis.

Claims (3)

a body formed so that a discharge groove for guiding and discharging chips extends from the distal end to the proximal end;
a cutting insert fastened and fixed to the tip side of the body,
The cutting insert is
a first surface having a through hole for inserting the fastening member;
a second surface opposite to the first surface and in contact with the insert seat of the body;
a main cutting edge that is formed to extend linearly at the end of the first surface and at least a portion of which is used for cutting;
is fastened and fixed to the body by the fastening member so that the first surface faces the inner side of the discharge groove and the main cutting edge protrudes further to the tip side than the tip of the body;
The body is formed with a protruding portion that protrudes so as to cover a part of the first surface of the cutting insert from the outside,
When viewed along the central axis of the body, the main cutting edge extends from the outer peripheral side of the body to a position straddling the central axis of the body,
The cutting insert is
a first corner cutting edge connected to the outer peripheral edge of the main cutting edge;
a second corner cutting edge located opposite the first corner cutting edge along the diagonal of the first surface;
The second corner cutting edge is covered by the protrusion,
The body is formed with a recess hole for preventing contact with the second corner cutting edge,
The cutting tool, wherein the recess hole is formed so as to extend from a surface of the body opposite to the projecting portion toward the second corner cutting edge. 2. The cutting tool according to claim 1, wherein the protrusion overlaps neither the main cutting edge nor the through hole when viewed along the central axis of the through hole. 2. The cutting tool according to claim 1 , wherein said recess hole is formed as a blind hole that does not pass through said protrusion.

Images