JP6025089B2 - Cutting insert, cutting edge replaceable cutting tool body and cutting edge replaceable cutting tool - Google Patents

Description

  The present invention relates to a cutting insert, a body, and a cutting edge exchangeable cutting tool including these. In particular, the present invention relates to a cutting insert and a cutting edge exchangeable cutting tool applicable to right-angle shoulder machining.

  Conventionally, as one of the types of cutting edge-exchangeable cutting tools in which a plurality of cutting inserts are mounted on the outer periphery of the tip of a substantially cylindrical body, a 90 ° wall surface as disclosed in Patent Document 1 (that is, (For right-angle shoulder cutting). The cutting insert disclosed in Patent Document 1 has a substantially triangular basic shape on the upper surface, and is configured to be usable on both sides. The cutting edges in each of the upper and lower surfaces have the same configuration. Each cutting edge includes a main cutting edge, a secondary cutting edge, a corner cutting edge, and an auxiliary cutting edge. In plan view, this cutting insert has a substantially triangular contour, and the side ridges and the corner edges are alternately connected. The secondary cutting edge and the corner cutting edge extend to the corner edge, and the main cutting edge and the auxiliary cutting edge extend to the side ridge between the corner edges. The secondary cutting edge is inclined from the corner cutting edge toward an imaginary intermediate plane defined to extend between the upper and lower surfaces to bisect the cutting insert. The main cutting edge is inclined from the corner cutting edge to the opposite intermediate side and further to the auxiliary cutting edge. As with the main cutting edge, the auxiliary cutting edge is inclined so as to approach the intermediate surface as it moves away from the corner cutting edge between the main cutting edge and the auxiliary cutting edge. The inclination degree of the auxiliary cutting edge with respect to the intermediate surface is smaller than the inclination degree of the main cutting edge, and the auxiliary cutting edge may be parallel to the intermediate surface. The auxiliary cutting edge thus extends from the associated main cutting edge and connects to a secondary cutting edge that is subordinate to an adjacent corner cutting edge.

International Publication No. 2014/006609

  When the cutting insert of Patent Document 1 is attached to a body and used for cutting, the working cutting edge has one corner cutting edge, the same cutting edge as the main cutting edge and the auxiliary cutting edge that sequentially extend from one end of the corner cutting edge. It consists of a secondary cutting edge extending from the other end of the cutting edge. In a side view, the working main cutting edge and the working auxiliary cutting edge extend so as to approach the intermediate surface as they move away from the working corner cutting edge. The action assisting cutting edge leads to a secondary cutting edge of an adjacent cutting edge that is not the working cutting edge. The secondary cutting edge is inclined so as to approach the intermediate surface as it is away from the corner cutting edge of the same cutting edge in a side view, and its length is clearly shorter than the length of the main cutting edge. Therefore, in the side view, the inclination angle of the secondary cutting edge with respect to the intermediate surface is much larger than the inclination angle of the main cutting edge with respect to the intermediate surface. Therefore, the change in the inclination direction at the connecting portion between the action assisting edge of the action cutting edge and the auxiliary edge of the non-action edge becomes abrupt. Therefore, in the cutting tool, when one cutting edge is acting, the non-working auxiliary cutting edge connected to the working auxiliary cutting edge extends in a direction that prevents the outflow of chips generated by the working cutting edge. As a result, the chips are prevented from proceeding to the proximal end side of the cutting tool by the non-acting auxiliary cutting edge, and are liable to stay near the distal end. As a result, chips may be caught between the tool and the workpiece, or the chips may damage the surface of the workpiece.

  Further, there is a case where cutting is performed by increasing the depth of cut and using almost the entire main cutting edge. In this case, in the cutting tool using the cutting insert of Patent Document 1, a force may be applied to the workpiece in the direction of scooping it up, particularly according to the inclination of the working main cutting edge. Therefore, it is necessary to hold the workpiece more firmly.

  Accordingly, the present invention provides a cutting insert created in view of at least one of the above circumstances, a tool body to which the cutting insert is detachably attached, and a cutting edge exchangeable cutting tool to which the cutting insert is detachably attached. The purpose is to provide.

According to one aspect of the invention,
A first end surface having a substantially polygonal shape, a second end surface facing the first end surface, a peripheral side surface connecting the first end surface and the second end surface, and a first end surface and the peripheral side surface A cutting insert comprising at least one cutting edge formed at the intersection,
The cutting edge comprises a first cutting edge part and a second cutting edge part connected to the first cutting edge part,
In the end view of the cutting insert with respect to the first end surface, the second cutting edge portion is located at the first corner portion of the two corner portions adjacent to each other of the first end surface, and the first cutting edge portion is Extending from the first corner portion to the side edge portion of the first end surface extending toward the adjacent second corner portion;
When the intermediate surface passing through the peripheral side surface passing between the first end surface and the second end surface is defined, the first cutting edge portion is configured to be concave toward the intermediate surface in a side view of the cutting insert. A first inclined portion on the first corner portion side and an inclined direction opposite to the inclined direction of the first inclined portion with respect to the intermediate surface, and the second corner portion side with respect to the first inclined portion Bei example and the second inclined portion located in, and a concave bottom portion connecting the first inclined portion and the second inclined portion,
The peripheral side further comprises one or more grooves with respect to the first cutting edge, each of the grooves having an opening at the first end face;
When defining a first axis extending through the first end surface and the second end surface, each of the grooves extends substantially parallel to the first axis;
At least one of the grooves intersects the first cutting edge at the concave bottom;
Provided with a plurality of cutting edges at the intersection of the first end surface and the peripheral side surface,
A plurality of cutting edges are provided at the intersection between the second end surface and the peripheral side surface,
The plurality of cutting edges associated with the first end face are rotationally symmetric about the first axis;
When defining a second axis that is orthogonal to the first axis and extends through the peripheral side surface, the second axis is included in the intermediate surface, and the plurality of cutting edges related to the second end surface are around the second axis. , Non-rotationally symmetric with the plurality of cutting edges with respect to the first end face,
A cutting insert is provided.

FIG. 1 is a perspective view of a cutting insert according to a reference example . FIG. 2 is a perspective view of the cutting insert of FIG. 1 viewed from another angle. FIG. 3 is a top view of the cutting insert of FIG. FIG. 4 is a side view of the cutting insert of FIG. FIG. 5 is a bottom view of the cutting insert of FIG. 6 is a perspective view of a cutting insert mounted blade edge replaceable cutting tool of FIG. FIG. 7 is a side view of the cutting edge exchangeable cutting tool of FIG. FIG. 8 is a front view of the cutting edge-exchangeable cutting tool of FIG. FIG. 9 is an enlarged view of the insert mounting seat of the tool body of the cutting edge exchangeable cutting tool of FIG. FIG. 10 is a schematic diagram for explaining a cutting mode of the cutting tool of FIG. Figure 11 is a perspective view of the insert according to the implementation embodiments of the present invention. FIG. 12 is a perspective view of the insert of FIG. 11 viewed from another angle. FIG. 13 is a top view of the insert of FIG. FIG. 14 is a bottom view of the insert of FIG. FIG. 15 is a side view of the insert of FIG. FIG. 16 is a schematic diagram for comparing the shapes of the cutting edge on the upper surface side and the cutting edge on the lower surface side. Figure 17 is a perspective view of the mounting the blade edge replaceable cutting tool the cutting insert of Figure 11. FIG. 18 is a side view of the cutting edge-exchangeable cutting tool of FIG. FIG. 19 is a front view of the blade-tip-exchangeable cutting tool shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, a reference example will be described.

A cutting insert 10 according to a reference example is shown in FIGS. The cutting insert 10 is formed for right-angle shoulder cutting. The cutting insert 10 includes two opposing end surfaces 20 and 30 and a peripheral side surface 40 that connects the two end surfaces 20 and 30. For ease of explanation, hereinafter, for convenience, one end surface 20 facing upward in FIG. 1 is referred to as an upper surface 20, and the other end surface 30 is referred to as a lower surface 30. One of the two end surfaces 20 and 30 corresponds to the first end surface of the present invention, and the remaining end surface corresponds to the second end surface of the present invention.

  The shape that approximates the upper surface 20 to a polygon is a triangle. The upper surface 20 has three edge portions LP and three corner portions CP. Here, the term “side edge” means an edge portion of the end surface extending between the corner portions, and more specifically, regarding the upper surface, a portion other than the curved portion of the corner portion of the edge portion of the upper surface. Say. In effect, one cutting edge is formed for one side ridge and one corner. As will be described later, each side ridge has a curved portion, and the curved portion can be considered as a corner portion, and the shape of the upper surface 20 can be regarded as a substantially hexagonal shape. However, in the following description, for convenience, each side ridge portion is regarded as having a curved portion that is convex outward. The upper surface 20 is regarded as a substantially triangular shape.

  Similarly to the upper surface 20, the lower surface 30 has a triangular shape that approximates a polygon. Therefore, the lower surface 30 has three side ridge portions and three corner portions, and one cutting edge is formed substantially for one side ridge portion and one corner portion. Note that, on the lower surface 30 as well as the upper surface 20, each side ridge portion is regarded as having an outwardly convex curved portion.

  The cutting insert 10 includes a through hole 50 that opens in the upper surface 20 and the lower surface 30. The upper surface 20 has a shape that is 120 ° rotationally symmetric with respect to the central axis A1 of the through hole 50. Similarly to the upper surface 20, the lower surface 30 has a shape that is 120 ° rotationally symmetric with respect to the central axis A <b> 1 of the through hole 50.

  The cutting insert 10 is a so-called negative type cutting insert. Therefore, no special positive or negative clearance angle is given to the side surface. Furthermore, even if the upper surface 20 and the lower surface 30 are turned upside down, they have the same shape. That is, FIG. 3 (top view or end view) when the cutting insert 10 is viewed from the side facing the upper surface 20 is the same as FIG. 5 (bottom view or end view) when the cutting insert 10 is viewed from the side facing the lower surface 30. It is. Therefore, the cutting insert 10 is 180 ° rotationally symmetric about the axis A2 that is determined to be orthogonal to the axis A1 and penetrate the peripheral side surface 40. However, in FIG. 1, one of the three symmetry axes is representatively shown as the axis A2.

  The cutting insert 10 includes three cutting edges 20E on the upper surface side and three cutting edges 30E on the lower surface side. The cutting edge 20E is formed at the intersection of the upper surface 20 and the peripheral side surface 40. The cutting edge 30E is formed at the intersection of the lower surface 30 and the peripheral side surface 40. As is clear from the above description, the cutting edges 20E and 30E have the same shape. Therefore, the cutting insert 10 is a cutting insert that can be used on both sides, can be indexed, and can be used six times. Each of the cutting edges is formed so that a part of the related end face functions as a rake face, and a side portion of the related peripheral side face functions as a flank face.

  Considering each cutting edge, the peripheral side surface 40 has a portion for each cutting edge, and can be roughly divided into three. Focusing on the cutting edge 20E on the upper surface 20 side, the peripheral side surface 40 can be divided into three side groups. Similarly, if focusing on the cutting edge 30E on the lower surface 30 side, the peripheral side surface 40 can be divided into three side surface groups. .

  Each of the cutting edges 20E and 30E includes a main cutting edge, a sub cutting edge, and a corner cutting edge connecting them. Details will be described below.

  A main cutting edge 22 is formed at each side ridge portion LP of the upper surface 20 and the lower surface 30, and a corner cutting edge 21 is formed at each corner portion CP of the upper surface 20 and the lower surface 30. In other words, the corner cutting edge 21 is formed in the curved portion of the corner portion CP of the upper surface 20 or the lower surface 30, and the main cutting edge 22 is formed on the side ridge portion LP that connects two adjacent corner cutting edges 21, particularly here. Formed entirely. The “main cutting edge” is a part of the cutting edge that bears the main part of the cutting process. In the cutting insert 10 of this embodiment, substantially the entire side ridge portion LP can be used as the main cutting edge during cutting.

  Further, in addition to the corner cutting edge 21, a secondary cutting edge 21 a is formed at each corner portion CP. Here, the auxiliary cutting edge 21a is formed in the corner portion CP. However, the minor cutting edge 21a may have a part in the corner portion and may extend beyond the corner portion to the side ridge portion, or the whole may be located in the side ridge portion.

Here, one cutting edge will be described. However, since the three cutting edges 20E on the upper surface side have the same shape and the three cutting edges 30E on the lower surface side have the same shape as the cutting edge 20E on the upper surface side, respectively, The cutting edge 20E will be described in detail. In the cutting insert of the reference example , the main cutting edge 22 corresponds to the first cutting edge portion in the present invention, and the corner cutting edge and the auxiliary cutting edge correspond to the second cutting edge portion in the present invention. Specifically, when the cutting insert 10 is attached to the body, the portion of the corner portion that cuts the bottom surface orthogonal to the wall surface becomes the secondary cutting edge. This secondary cutting edge is viewed from above as shown in FIG. Located in the corner. That is, when attention is paid to the cutting edge 20 </ b> E positioned below in the top view of the cutting insert 10 in FIG. 3, the corner cutting edge 21 and the sub-cutting edge 21 a forming the second cutting edge portion are adjacent to each other on the upper surface 20. An upper surface 20 located at one first corner portion CP1 of the two corner portions CP and having a main cutting edge 22 as a first cutting edge portion extending from the first corner portion CP1 toward the adjacent second corner portion CP2. It extends to the side ridge part LP. When the secondary cutting edge does not extend to the corner portion, the secondary cutting edge is not included in the second cutting edge portion of the present invention.

  As shown in FIG. 3, when each main cutting edge 22 is viewed in a top view, the main cutting edge 22 has a portion that is convexly curved outward. Specifically, the side ridge portion LP from which the main cutting edge 22 extends generally has a curved portion 22a that curves in a convex manner toward the outside of the cutting insert 10, and first and second linear shapes in a top view. Portions 22b and 22c. These linear portions 22b and 22c are continuous on both sides of the curved portion 22a. Further, the main cutting edge 22 in one cutting edge 20E extends over substantially the entire side ridge between the corners so as to be continuous with the sub-cutting edge 21a of the adjacent cutting edge 20E.

  In the top view of the cutting insert 10 of FIG. 3, each side ridge portion LP has a mirror image symmetrical shape with respect to the virtual line S (overlapping the axis A <b> 2). Of the ends of the two linear portions 22b and 22c, a straight line connecting ends on the side away from the curved portion 22a is a string (in FIG. 3, an extension line of the string is shown as E1). Then, the virtual line S is a line that is perpendicular to the string and passes through the center of the string. In FIG. 5, a virtual line T on the lower surface 30 side corresponding to the virtual line S is shown.

  As shown in FIG. 4, when the main cutting edge 22 on the upper surface 20 side is viewed in a side view of the cutting insert 10 (view of the cutting insert from the direction along the axis A <b> 2 in FIG. 1), the main cutting edge 22 is the lower surface. Curved to dent toward 30. In particular, in the cutting insert 10, the main cutting edge 22 is concavely curved so as to draw one smooth concave curve as a whole in a side view. In FIG. 4, the main cutting edge 22 includes a first inclined portion 23a connected to the corner cutting edge 21 in the same cutting edge 20E, a second inclined portion 23b connected to the adjacent cutting edge 20E, and the first and second inclined portions. And a concave bottom portion (curved portion in this case) 23c extending so as to connect them therebetween. The lowest point of the curved portion 23, that is, the location where the curved portion 23 is closest to the lower surface 30 (that is, the bottom) is near the center of each side ridge. However, strictly speaking, in the side view of the main cutting edge 22, the bottom is shifted from the center of the main cutting edge 22 to the corner cutting edge side of the same cutting edge. More specifically, in the cutting insert 10 of the present embodiment, only 6% of the length of the side ridge portion LP between the two corner portions from the center between the two adjacent corner portions CP1 and CP2 is used. The bottom part of the concave bottom part 23c is arranged at a place near the left corner part (the first corner part) CP1. Note that the length of the side ridge portion LP may be determined on a plane orthogonal to the central axis of the through hole. Therefore, when a plane (not shown) including the central axis A1 and the axis A2 is defined, the bottom of the concave bottom 23c is shifted from the plane toward the first corner CP1.

  In the main cutting edge 22 and the side ridge portion LP, the first linear portion 22b in the top view corresponds to the first inclined portion 23a in the side view, and the second linear portion 22c in the top view is in the side view. Corresponding to the second inclined portion 23b, the curved portion 22a in the top view corresponds to the concave bottom portion 23c in the side view. However, they are not perfectly consistent with each other.

  Here, a surface perpendicular to the axis A <b> 1 and extending so as to penetrate the peripheral side surface 40 in the cutting insert 10 is defined as an intermediate surface M. Here, the intermediate surface M is determined so as to divide the cutting insert 10 into two equal parts, and includes the axis A2. The main cutting edge 22 of the cutting edge 20E is curved so that both sides are linear in the top view of the cutting insert 10 and convex outwardly at the center, and each end of each side in the side view. It is comprised so that it may incline toward the intermediate surface M and may approach the intermediate surface M most at the concave bottom part 23c. That is, the main cutting edge 22 is configured in a concave shape toward the intermediate surface M in a side view. Therefore, in the side view of the cutting insert 10, the first inclined portion 23a is inclined so as to approach the intermediate surface M as the distance from the corner cutting edge 21 in the same cutting edge 20E increases. Similarly, the 2nd inclination part 23b inclines so that the intermediate surface M may be approached, as it leaves | separates from the sub-cutting edge 21a in the adjacent cutting edge 20E. However, in the side view, the inclination direction with respect to the intermediate surface M of the first inclined portion 23a is opposite to the inclination direction with respect to the intermediate surface M of the second inclined portion 23b. Therefore, in FIG. 4, when the inclination with respect to the intermediate surface M of the first inclined portion 23a is represented by an angle α, the angle α is measured clockwise from the reference surface, and the inclination with respect to the intermediate surface M of the second inclined portion 23b is the angle β. When represented, the angle β is measured counterclockwise from the reference plane. As shown in FIG. 4, the angle α is determined to be slightly larger than the angle β, but may be the same or vice versa. In the side view of FIG. 4, here, the first and second inclined portions 23 a and 23 b each have a certain inclination angle with respect to the intermediate surface M. However, the first inclined portion 23a may be inclined so that the inclination angle with respect to the intermediate surface M becomes smaller as it is away from the corner cutting edge 21 to which the first inclined portion 23a is connected, and the second inclined portion 23b is separated from the auxiliary cutting edge 21a to which it is connected. As the distance increases, the inclination angle with respect to the intermediate surface M may be decreased. In the side view of FIG. 4, only one of the first and second inclined portions 23 a and 23 b may have a certain inclination angle with respect to the intermediate surface M.

  The secondary cutting edge 21 a is inclined so as to approach the intermediate surface M as it is away from the corner cutting edge 21 in the same cutting edge in a side view of the cutting insert 10.

  The upper surface 20 has an abutting surface 24 configured to be able to abut against a wall surface of a body described later. The contact surface 24 extends around the through hole 50. The cutting edge 20 </ b> E of the upper surface 20 is at a position higher than the contact surface 24. That is, the distance from each portion of the cutting edge 20E (the corner cutting edge 21, the main cutting edge 22 or the auxiliary cutting edge 21a) of the upper surface 20 to the lower surface 30 or the intermediate surface M is from each portion of the contact surface 24 to the lower surface 30 or intermediate. It is longer than the distance to the surface M. A contact surface 34 is also formed on the lower surface 30, and the relationship between the contact surface 34 and the cutting edge 30E is the same as the relationship between the contact surface 24 and the cutting edge 20E.

  As shown in FIG. 3, the upper surface 20 is formed with a contact surface 24 that contacts the bottom wall surface of the insert mounting seat formed on the body when the cutting edge of the lower surface 30 is the working cutting edge. The contact surface 24 includes three recesses 25. The number of recesses 25 matches the number of cutting edges 20E. Each recessed part 25 is arrange | positioned in the vicinity of the concave bottom part 23c of FIG. 4 in the main cutting edge 22 of the related cutting edge 20E. Accordingly, the concave portion 25 located near the lower main cutting edge 22a in FIG. 3 intersects the imaginary line S. In particular, each concave portion 25 is formed with respect to the above-mentioned bottom portion among the concave bottom portions 23c, and extends inside the bottom portion (in a direction substantially perpendicular to the cutting edge in FIG. 3). A portion corresponding to the rake face extends between the recess 25 and the cutting edge 20E.

  Also on the lower surface 30, as with the upper surface 20, a contact surface 34 is formed. The contact surface 34 is provided with three recesses 35. The relationship between the contact surface 34 and the cutting edge 30E is the same as the relationship between the contact surface 24 and the cutting edge 20E. Moreover, the recessed part 35 has the same shape as the recessed part 25, and is provided with respect to the main cutting edge of the cutting edge 30E similarly to the recessed part 25.

  Next, a description will be given of a cutting edge replaceable cutting tool to which the above-described cutting insert 10 is detachably mounted. The cutting edge-replaceable cutting tool 100 according to the first embodiment includes the above-described cutting insert 10 and a substantially cylindrical tool body 110. The cutting tool 100 is configured to be suitable mainly for right-angle shoulder machining.

  The body 110 has an axis A3 extending from the distal end portion to the proximal end portion. Three insert mounting seats 120 for mounting the cutting insert 10 are formed at the tip of the body 110 at equal intervals in the circumferential direction.

  The insert mounting seat 120 includes two side wall surfaces 121 (121a, 121b) and a bottom wall surface 122 that extends at a substantially right angle so as to intersect with the two side wall surfaces 121 (121a, 121b). When the cutting insert 10 is attached to the insert mounting seat 120, the side surface portion of the peripheral side surface of the cutting insert 10 contacts the side wall surface 121, and the upper surface 20 or the lower surface 30 contacts the bottom wall surface 122.

  In the insert mounting seat 120, the cutting insert 10 is placed so that the entire main cutting edge 22 is positioned on the outer peripheral side of the body 110. Strictly speaking, when the cutting edge 100 is rotated about its rotation axis A3, the cutting insert 10 is in such a posture that the rotation trajectory of the main cutting edge 22 draws a cylindrical surface substantially parallel to the rotation axis. It is mounted on the insert mounting seat 120. Therefore, when the cutting tool 100 is viewed from the direction facing the bottom wall surface 122 of one insert mounting seat 120, the cutting insert 10 has a main cutting edge (working main cutting edge) used on the rotation axis A3 of the tool body 110. It is attached so as to be substantially parallel to the surface. Further, in order to prevent the side surface portion of the peripheral side surface 40 of the cutting insert 10 from coming into contact with the surface of the workpiece, the cutting insert 10 is tilted and placed on the front side in the rotational direction of the cutting edge exchangeable cutting tool 100. That is, the cutting insert 10 is attached to the body 110 of the cutting edge exchangeable cutting tool 100 so that various positive clearance angles are given to the flank of the negative type cutting insert 10.

Next, the operation and effect of the cutting insert 10 of the reference example and the cutting tool 100 to which the cutting insert 10 is detachably attached will be described.

  The cutting tool 100 is rotated about the axis A3 and moved relative to the workpiece. Thereby, right-angle shoulder machining can be performed. The axis A3 is a relative rotation axis with respect to the workpiece of the cutting tool. The cutting tool 100 may be fixed and the workpiece may be rotated.

  In the side view of the cutting insert 10 shown in FIG. 4, the main cutting edge 22 has a concavely curved shape and includes a curved portion 23 c that is recessed from the upper surface 20 toward the lower surface 30. In addition, the lowermost portion, that is, the concave bottom portion in the side view of the curved portion 23c is near the center of the side ridge portion. Accordingly, it is possible to favor the outflow or discharge of chips.

Here, the cutting insert of patent document 1 and the cutting insert 10 of a reference example are compared. In the cutting insert of Patent Document 1, as described above, the secondary cutting edge of the cutting edge that is not the working cutting edge extends on the extension of the working main cutting edge. This conventional secondary cutting edge extends in a direction that obstructs the flow of chips from the working cutting edge (that is, has a large rising angle with respect to the intermediate surface), and the rake face portion connected to the secondary cutting edge is the same. Can work to hinder its flow. Therefore, the flow direction of chips is directed to the tip side of the cutting tool by the non-acting secondary cutting edge and its surroundings, and the chips are sandwiched between the tool and the workpiece, or the surface of the workpiece is damaged. Can happen. However, in the cutting insert 10 of the reference example , the main cutting edge itself is smoothly and gently curved in a side view, so that the rising angle (corresponding to the angle β) of the second inclined portion 23b is particularly small. Since the inclined portion 23b rises gently from the concave bottom portion 23c, the chips can be smoothly directed toward the base end in the direction along the axis A3 of the cutting tool. Therefore, according to the cutting insert 10 and the cutting tool 100, the outflow resistance of chips can be reduced, the occurrence of vibrations such as chatter can be suppressed, and the accuracy of the work surface can be increased.

  In order to ensure such outflow of chips, the angle α is inclined with respect to the intermediate surface M of the first inclined portion 23a, and the angle β is inclined with respect to the intermediate surface M of the second inclined portion 23b. It is good not to have an angle difference. For example, the difference between the magnitude of the angle α and the magnitude of the angle β may be 10 ° or less. Further, the angle α is preferably 20 ° or less, and the angle β is preferably 20 ° or less.

  Further, in the cutting tool 100, when the cutting is performed, particularly when the cut into the workpiece is large, not only the first force in the direction of pushing up the workpiece but also the second force in the direction of pushing down the workpiece is appropriately set. Can be generated. FIG. 10 shows a part of the tip of the cutting tool of FIG. In FIG. 10, the workpiece is omitted, but not only the first inclined portion 23 a of the main cutting edge 22 but also the concave bottom portion 23 c and the second linear portion 22 c are used for processing the workpiece. The first force F1 and the second force F2 are schematically represented by paying attention only to their relative directions. According to the cutting insert 10 and the cutting tool 100, the force (component) of the first force F1 facing the proximal end side of the cutting tool can be reduced by the second force F2 including the component facing the distal end side of the cutting tool. Therefore, the force which lifts up a workpiece at the time of cutting can be suppressed. Therefore, according to the cutting insert 10 and the cutting tool 100, the effect that the holding force of a workpiece is not required as in the related art can be achieved.

  The main cutting edge 22 has a concavely curved shape in a side view of FIG. 4, but the cutting edge 100 includes a curved portion 22a in a side ridge portion from which the main cutting edge 22 extends in a top view or an end view. A wall with a high squareness can be processed. For example, when a cutting insert whose main cutting edge is composed of only a single straight line when mounted on the body with a positive or negative axial rake, the locus about the axis A3 drawn by the central portion of the main cutting edge is shown. Falls inside the same trajectory drawn by the end of the main cutting edge. Therefore, the processed wall surface has a shape in which the central portion is raised to the front. However, the main cutting edge 22 of the cutting insert 10 according to the first embodiment has a shape in which the center portion is convexly curved outward when viewed from above, so that the cutting insert 10 has an appropriate size. When mounted on the body 110 by the axial rake, the locus around the axis A3 of each part of the main cutting edge 22 is approximated on the same cylindrical surface. Therefore, the cutting tool 100 provided with the cutting insert 10 of the first embodiment can process a wall having a high squareness on the workpiece.

  Here, first consider the case where the cutting edge 20E on the upper surface 20 is the working cutting edge. The main cutting edge 22 has a concave bottom 23c in a side view and is concavely curved. Therefore, by cutting with the cutting tool 100, chips having a cross-sectional shape bent into a V shape corresponding to the cutting edge shape in a side view are generated. On the other hand, the cutting edge 20E is at a position higher than the contact surface 24 as a whole (a position away from the intermediate surface M). Therefore, the V-shaped chip tends to reach the contact surface 24. However, in the cutting insert 10, since the concave portion 25 is provided in the vicinity of the substantially central portion of the main cutting edge, the V-shaped central portion of the chip rubs against the bottom portion of the concave portion 25, and both end portions of the chip are formed. Chips are likely to leave the cutting insert 10 before contacting the abutment surface 24. For this reason, it is suppressed that the contact surface 24 is rubbed by a chip, and damage to the contact surface 24 is prevented. Therefore, the contact surface 24 that is flat in the cutting insert 10 is maintained in a substantially flat state. Accordingly, when the cutting edge 30E on the lower surface 30 side is used after the cutting edge 20E on the upper surface 20 side is used, the contact surface 24 of the upper surface 20 sufficiently contacts the bottom wall surface 122 of the insert mounting seat 120. Can be made. Similarly, when using the cutting edge 20E on the upper surface 20 after using the cutting edge 30E on the lower surface 30, the abutment surface 34 is clean, so that the cutting insert 10 is stably mounted on the insert mounting seat. In addition, it is preferable that the recessed part 25 and the recessed part 35 are the minimum required size in consideration of the range which a chip | tip scrapes strongly from a viewpoint of ensuring the stability of attachment of a cutting insert. In other words, the smaller the size of the contact surface 24 and the contact surface 34, the lower the mounting stability of the cutting insert. Therefore, the recess 25 and the recess 35 scrape chips into the contact surface 24 and the contact surface 34. It is preferable that the size is a minimum size that does not cause an effect.

  Moreover, the side ridge part LP where the main cutting edge 22 extends includes the linear portions 22b and 22c, so that the side portions of the cutting insert intersect with the end surfaces (upper and lower surfaces) become the linear portions 22b and 22c. Therefore, it becomes easy to make the surface contact with the side wall surface 121 (121a, 121b) of the insert mounting seat 120 shown in FIG. 9 more firmly with a sufficient contact area. That is, when the side ridge portion includes the linear portions 22b and 22c, the side surface portion (contact surface) having the linear portions 22b and 22c at the edges can be substantially flat. For this reason, the side wall surfaces 121a and 121b (as contacted surfaces) of the corresponding insert mounting seats 120 can also be substantially flat. Since it is not necessary to form the wall surface of the insert mounting seat 120 as a complicated curved surface shape, it is possible to easily form the wall surface of the insert mounting seat 120 so as to match the shape of the cutting insert 10 with high accuracy. This makes it easier to bring the side surface portion as the contact surface of the cutting insert into surface contact with the contacted surface of the insert mounting seat. This improves the mounting stability of the cutting insert 10.

  The cutting insert 10 has six cutting edges 20E and 30E in total, and can be used six times. The cutting insert 10 is a so-called negative type cutting insert that is configured so that the peripheral side surface 40 is substantially parallel to the central axis A1 of the through-hole 50, and can use a cutting blade having the same shape even if it is turned upside down. . For this reason, the cutting insert 10 is economical because a cutting edge is formed on the lower surface 30 in addition to the upper surface 20.

  Further, as described above, when each of the side ridges when viewed from above and viewed from below is a mirror image symmetrical shape, the cutting insert 10 is manufactured with a simple die having a simple shape. Manufacturing costs can be reduced. That is, it can be manufactured as a normal negative type cutting insert in which cutting edges are formed on both sides.

The reference example has been described above, but various modifications can be made. For example, the above-described cutting insert 10 is a negative type, but the portion corresponding to the flank is orthogonal to the central axis of the through-hole and is configured to form an acute angle with respect to the plane passing through the cutting edge. It does not matter. Further, cutting edges may be formed on both the upper and lower surfaces, and only the vicinity of the upper and lower surfaces of the side surface may be a positive type, and the entire side surface may have a concave shape.

  Furthermore, in the said cutting insert, the end surface part used as a rake face was formed so that it might have a positive rake angle (refer FIG.1, FIG.2 and FIG.4). However, various convex portions and concave portions may be further provided on each end face.

In the reference example described above, the basic shape of the upper surface and the lower surface is a triangle, but may be another polygon such as a quadrangle. When the basic shape of the upper and lower surfaces is triangular or quadrangular like the above-mentioned cutting insert 10, the cutting insert is designed to be suitable for right-angle shoulder cutting where chip discharge is important as described above. obtain. In that case, the above effect functions more effectively.

In the reference example described above, the side ridge portion where the main cutting edge extends is composed of a curved portion and a linear portion in a top view, but may be composed of only a curved portion. Further, as long as the trajectory of the entire main cutting edge around the tool axis is approximated on the same cylindrical surface, there may be three or more linear portions on the main cutting edge or the side ridge.

In the reference example described above, the bottom of the concave bottom 23c is located at a position shifted from the center between two adjacent corners to one side by 6% of the length of the side ridge between the two corners. It was. However, a sufficient effect can be obtained if a range of 10% or less of the length of the side ridge portion is determined on the left and right with the center between two adjacent corner portions as a base point, and the bottom of the concave bottom portion 23c is disposed within the range. Arise. In other words, the bottom of the concave bottom 23c can be shifted in the left or right direction from the center between the two corners up to 10% of the length of the side ridge.

In the reference example described above, the side ridges on the upper surface and the lower surface are mirror-symmetrical shapes in the top view and the bottom view, respectively, but are not limited thereto. In the case of a cutting tool for right-angle shoulder machining, the trajectory of the entire main cutting edge may be approximated on the same cylindrical surface.

  The recesses 25 and 35 can also be applied to a cutting insert in which a cutting edge is formed only on one side. For example, when the cutting edge 20E is formed only on the upper surface 20 side, it is possible to prompt the chip to be separated from the cutting insert by providing the recess 25 as described above. Therefore, it is possible to prevent the upper surface 20 from being damaged by scraping of chips. This contributes to keeping the unused cutting edge on the upper surface 20 side in a good state.

Next, a description will be given implementation of the invention. The cutting insert 210 of the implementation form comprises further provided with form a so-called nick to the cutting insert embodiment. Cutting tool 400 of the implementation form, corresponding to the characteristic portion of the cutting insert of implementation form, with the differences between the cutting tool of the above embodiment. Therefore, in the following, the differences will be described, and the components corresponding to those already described are denoted by the same reference numerals, and description thereof will be omitted.

  A plurality of grooves 41 are provided in the peripheral side surface 40. These grooves are so-called “nicks” and are hereinafter referred to as “nicks”.

  Each nick 41 extends substantially parallel to the axis A1 of the through hole 50 and opens on each of the upper and lower surfaces 20 and 30. The component part of the nick 41 is retracted inside the cutting insert 100 rather than the other side part, and does not function as a cutting edge. In addition, from the relationship with the cutting insert of the first embodiment, it is described that the cutting insert 10 is further provided with a nick. However, in the present invention, the nick is created at the same time as the cutting edge, for example, when the cutting insert is created. It should be noted that it includes a cutting insert formed.

  Three nicks 41 are formed on the peripheral side surface 40 with respect to the cutting edge 20E on the upper surface 20 side. Of the three nicks, the middle nick 41 is positioned so as to include the bottommost portion in a side view of the main cutting edge.

  When viewed from the side (that is, in FIG. 15), the nick 41 is not disposed symmetrically with respect to the main cutting edge 22. In the second embodiment, the nick 41 is formed closer to the corner cutting edge 21 in the main cutting edge 22 of the cutting edge 20E on the upper surface 20 side in the cutting edge 20E. By forming the nick 41 in this manner, the position of the nick 41 viewed from the upper surface 20 side and the position of the nick viewed from the lower surface 30 side are shifted without overlapping. Therefore, as will be described later, there is no uncut residue when the cutting insert 210 is mounted on the body and processed. This will be described with reference to the drawings.

  The solid line in FIG. 16 indicates the outer shape of the cutting insert 210 viewed from the upper surface 20 side (see FIG. 13), and the broken line indicates the outer shell shape of the cutting insert 210 viewed from the lower surface 30 side (see FIG. 14). ). As can be understood from FIG. 16, at the time of cutting, the portion of the working cutting edge where the nick 41 is formed does not function as a cutting edge, and the portion corresponding to the nick 41 is left uncut. However, in the cutting insert 10, the plurality of nicks 41 are formed so as not to be disposed at symmetrical positions in a side view of the cutting insert 10 as viewed from the direction along the axis A <b> 2 (see FIG. 15). Therefore, a portion acting as the cutting edge of the main cutting edge 22 on the lower surface 30 overlaps with the position of the opening of the nick 41 formed on the upper surface 20. That is, by using the cutting insert 210 having the cutting edge 20E on the upper surface 20 as the working cutting edge together with the cutting insert 210 having the cutting edge 30E on the lower surface 30 as the working cutting edge, the cutting insert 20E is cut by the cutting edge 20E on the upper surface 20. The missing edge can be cut by the cutting edge 30E of the lower surface 30. As is clear from FIG. 16, the portion acting as the cutting edge of the working main cutting edge 22 on the upper surface 20 overlaps the position of the opening of the nick 41 formed on the lower surface 30, so that the working cutting edge 30 </ b> E on the lower surface 30 The portion that has not been cut can be cut by the action cutting edge 20E of the upper surface 20. Thus, in the cutting insert, when the top view and the bottom view are overlapped, the plurality of nicks 41 are formed so that the nicks do not overlap each other. Therefore, the three cutting edges 30E regarding the lower surface 30 are non-rotationally symmetric with respect to the three cutting edges 20E regarding the upper surface 20 around the axis A2. That is, the cutting edge 20E has a shape different from that of the cutting edge 30E.

  The lowest point (that is, the bottom) P of the concave bottom 23c is based on the center of the length L (length along the plane perpendicular to the axis A1) from one corner to the other corner in a side view. A region on the left and right sides with a limit corresponding to a length corresponding to 10% of the length L, preferably a length corresponding to 8%, more preferably a length corresponding to a length corresponding to 6%. It should be within R. That is, the lowest point P of the concave bottom portion 23c is arranged at some location in the region R whose center is located between the two corners and whose size is 20%, preferably 16% of the length L. Good. A more preferable size of the region R is 12% of the length L. As is apparent from the description in the first embodiment, the “lowest point P” is the point closest to the intermediate surface M among the side ridges of the upper surface 20 or the lower surface 30 that can be seen when viewed from the side. Say. Note that the area where the bottom of the concave bottom can exist is also applied to the first embodiment.

  Next, a description will be given of a blade-tip-exchangeable cutting tool on which the above-described cutting insert 210 is mounted. As shown in FIGS. 17 to 19, the blade-tip-exchangeable cutting tool 400 of the second embodiment includes the above-described cutting insert 210 and a substantially cylindrical body 410. Four insert mounting seats 420 for mounting the cutting insert 210 are formed on the outer periphery of the front end portion of the body 410. Of the four cutting inserts 210 mounted on the four insert mounting seats 420, two cutting inserts 210a are mounted such that the upper surface 20 is a rake face (facing the front in the rotational direction), and the remaining two The two cutting inserts 210b are placed so that the lower surface 30 is a rake face. The cutting insert 210a and the cutting insert 210b are alternately arranged. By doing in this way, the rotation locus of the action cutting edge 20E on the upper surface 20 and the rotation locus of the action cutting edge 30E on the lower surface 30 are overlapped, and the cutting edge 20E and the cutting edge 30E are mutually connected at a place not cut by the nick 41. Since they cut each other, they can cut without making any uncut material. With respect to the radial direction centered on the rotation axis A3 of the blade-tip-exchangeable cutting tool 400, the cutting insert 10 is inclined and attached to the front side in the rotational direction as it goes toward the center side (axis A3 side) of the blade-tip-exchangeable cutting tool 400. The By mounting in this way, it is possible to prevent the peripheral side surface 40 of the cutting insert 10 from contacting or interfering with the surface of the workpiece. In other words, the negative type cutting insert 210 can be placed on the body 410 of the cutting edge-exchangeable cutting tool 400 with an appropriate positive clearance angle.

  Like the main cutting edge 22 of the cutting edge 20E on the upper surface side of the cutting insert 210, it is curved so as to be recessed downward from the upper surface 20 side toward the lower surface 30 side, and the position of the lowest point (bottom portion) P (see FIG. 15) is substantially in the middle of the two corners, the direction of the outflow of chips flowing out from the first inclined part 23a of the main cutting edge 22 and the second inclined part 23b of the main cutting edge 22 The outflow direction of the chips flowing out from each is directed to the lowest point P of the cutting edge. Therefore, the chips may interfere with each other and the flow of the chips may deteriorate. That is, the chips are generated while curling so as to gather in the direction of the lowest point P on both end sides of the main cutting edge, and when the chips grow to some extent, the flow of the chips deteriorates, and at the same time the lowest point P of the cutting edge. There is also a possibility that the stress applied in the vicinity will be high. Therefore, the nick 41 is formed in the cutting insert 210 so as to suppress the occurrence of such a phenomenon. Further, three nicks 41 are provided for one side ridge portion LP between the corner portions CP, and one nick 41a (see FIG. 15) in the center includes the lowest point P of the side ridge portion. It is formed in such a position. Therefore, the chips are subdivided, and the subdivided chips hardly interfere with each other's outflow. In particular, since the nick 41a is formed across the lowest point P of the side ridge where stress is most likely to be concentrated during the cutting process, the nick 41a is not involved in cutting, and a large stress is not generated.

  In the embodiment described above, the concave bottom portion 23c of the main cutting edge has a shape curved so as to be recessed toward the other end surface, but may be formed substantially parallel to the intermediate surface M. In the case where the concave bottom portions are formed so as to be substantially parallel to each other, 50% or more of the concave bottom portions may be included in the region R.

  Although the present invention has been described with a certain degree of specificity in the above-described embodiments, the present invention is not limited to these. It should be understood that various changes and modifications can be made to the present invention without departing from the spirit and scope of the claimed invention. That is, the present invention includes all modifications, applications, and equivalents included in the concept of the present invention defined by the claims.

Claims (10)

A substantially polygonal first end surface (20), a second end surface (30) opposite to the first end surface, and a peripheral side surface (40) connecting the first end surface and the second end surface And a cutting insert comprising at least one cutting edge (20E) formed at the intersection of the first end surface and the peripheral side surface,
The cutting edge includes a first cutting edge portion (22) and a second cutting edge portion (21, 21a) connected to the first cutting edge portion,
In the end view of the cutting insert with respect to the first end surface, the second cutting edge portion is located at a first corner portion of two corner portions (CP) adjacent to each other of the first end surface. The first cutting edge portion extends to the side ridge portion (LP) of the first end surface extending from the first corner portion toward the adjacent second corner portion,
When the intermediate surface (M) that passes between the first end surface and the second end surface and passes through the peripheral side surface is defined, the first cutting edge portion (22) in the side view of the cutting insert, The first inclined portion (23a) on the first corner portion side and the inclined direction opposite to the inclined direction of the first inclined portion with respect to the intermediate surface are configured to be concave toward the intermediate surface. A second inclined portion (23b) positioned on the second corner portion side with respect to the first inclined portion, and a concave bottom portion (23c) connecting the first inclined portion and the second inclined portion. Bei to give a,
The peripheral side surface further comprises one or more grooves (41) with respect to the first cutting edge, each of the grooves having an opening in the first end surface;
When defining a first axis (A1) extending so as to penetrate the first end surface and the second end surface, each of the grooves extends substantially parallel to the first axis,
At least one of the grooves intersects the first cutting edge at the concave bottom,
A plurality of cutting edges (20E) are provided at the intersection between the first end surface and the peripheral side surface,
Provided with a plurality of cutting edges (30E) at the intersection of the second end surface and the peripheral side surface,
The plurality of cutting edges with respect to the first end face are rotationally symmetric with respect to the first axis;
When defining a second axis (A2) that is orthogonal to the first axis and extends through the peripheral side surface, the second axis is included in the intermediate surface, and the plurality of cutting edges related to the second end surface Is non-rotationally symmetric with the plurality of cutting edges about the first end surface about the second axis.
Cutting insert ( 210 ).   The cutting insert according to claim 1, wherein the first cutting edge portion (22) is at least partially curved outwardly in the end face view of the cutting insert with respect to the first end face.   When defining a range of 10% or less of the length of the side ridge portion on the both sides from the center between the two corner portions of the side ridge portion where the first cutting edge portion extends, The cutting insert according to claim 1, wherein the concave bottom (23c) has a bottom.   The cutting insert according to claim 1 or 2, wherein the side ridge portion (LP) is formed substantially mirror-symmetric between the two adjacent corner portions in the end face view of the cutting insert.   The cutting insert according to any one of claims 1 to 3, wherein the first cutting edge portion (22) includes at least one linear portion on each end side in the end face view of the cutting insert. . The first end face (20) has a number of recesses (25) corresponding to the number of cutting edges (20E) of the first end face, and each recess (25) is the first end face. Provided in the vicinity of the concave bottom (23c) of the first cutting edge (22) of the related cutting edge (20E) of (20),
The cutting insert according to any one of claims 1 to 4. The groove intersects the first cutting edge at the bottom of the concave bottom.
The cutting insert according to claim 1 . When overlaid with an end face view of the end view and the second end surface of said first end surface (20) (30),
The grooves (41) do not overlap each other;
The cutting insert according to claim 1 . A body of a cutting edge exchangeable cutting tool, comprising an insert mounting seat (120) for detachably mounting the cutting insert according to any one of claims 1 to 8 . A cutting edge changeable cutting tool ( 400 ) comprising a tool body ( 410 ) with at least one insert mounting seat,
A cutting edge exchangeable cutting tool, wherein the cutting insert according to any one of claims 1 to 9 is detachably attached to the insert mounting seat.

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