JP2021186945A - Cutting insert - Google Patents

Abstract

To provide a cutting insert that is able to improve chip disposability even if a processing condition is such that an amount of cut is relatively large in a post-grinding process.SOLUTION: A lateral cutting edge 220 extends diagonally backward so as to increase the width of a cutting face. On the cutting face, a breaker groove 170 extending forward and backward is formed, and its groove face is, in a cross-section perpendicular to the blade edge of the lateral cutting blade 220, apart from the blade edge 220a and has a downward sloping surface 173, the lowest groove face 175, and an upward sloping face 177 toward the end edge 250 of an opposite cutting face. The upward sloping surface 177 has a gentle slope in which an inclination angle becomes smaller toward the rear end of the blade edge of the lateral cutting blade 220 from the front end thereof. In a post-grinding process, because chips cut by the lateral cutting blade 220 are subject to significant deformation from the front-end-side upward sloping face 177 of the lateral cutting blade 220, which has a relatively steep slope, and are subject to little deformation from the rear-end-side upward sloping face, which has a relatively gentle slope, cutting resistance is reduced. As a result, chip disposability is improved.SELECTED DRAWING: Figure 4

Description

The present invention relates to a cutting insert used for turning, and more particularly to a cutting insert suitable for post-grinding and the like.

In the outer diameter machining by lateral feed of post-grinding, when the rake face of the cutting edge of the cutting tool (cutting insert fixed to the holder) is viewed from above, the front cutting edge and one end thereof are connected diagonally backward. The lateral cutting edge extending to is responsible for the main cutting. This horizontal cutting edge is formed so that the cutting edge extends diagonally backward from one end of the cutting edge of the front cutting edge with a horizontal cutting edge angle shaped to widen the width of the rake face with respect to a virtual straight line drawn in the vertical feed direction. It is usually done.

In the post-grinding process, when cutting is performed with such a transverse cutting edge, chips flow and are discharged along the rake face basically in the direction perpendicular to the transverse cutting edge (blade edge). As for the cutting insert used for the post-grinding process, the smaller the lateral width of the rake face (the width dimension of the rake face in the lateral feed direction), the smaller the lateral cutting edge angle. For this reason, the groove width is narrow during grooving with such a cutting insert, and chips tend to come into contact with the machined wall surface (end face) at the initial stage of lateral feed, and the end face is easily damaged. .. Further, since the groove width is narrow, chips are likely to be clogged or entangled, which may not only reduce the roughness of the machined surface but also cause the cutting edge to break. Therefore, in the post-grinding process, it is important to smoothly discharge the chips (hereinafter referred to as chip disposability).

Under these circumstances, there is a cutting insert described in Document 1 (WO 2015/129836 A1), which is said to be suitable for post-grinding as described above. In this cutting insert, the breaker groove has a down slope and an up slope in order from the front cutting edge side and the lateral cutting edge side on the rake face. A front wall surface facing the front cutting edge is formed on the ascending slope on the front cutting edge side, and a lateral wall surface facing the lateral cutting edge is formed on the ascending slope on the lateral cutting edge side. The opening angle θ1 from the rake face end of the wall surface is set to be larger than the opening angle θ2 from the rake face end of the lateral wall surface. According to the cutting insert described in Document 1, a large amount of chips generated from the front cutting edge side at the initial stage of post-grinding and grooving are easily discharged by deforming the chips by the front wall surface having a large opening angle θ1. In addition, chips generated a lot from the lateral cutting edge side when performing lateral feed machining while advancing the cutting insert backward are easily deformed by the lateral wall surface having a small opening angle θ2 and discharged, resulting in machining. It is said that chips can be discharged smoothly over the entire process.

International Publication No. 2015/129836

However, in the cutting insert described in this document 1, chips generated from the lateral cutting edge side in the outer diameter machining at the time of lateral feed are cut even if the chips are deformed by the lateral wall surface having a small opening angle θ2 and discharged. Deformation control of debris cannot be sufficiently performed, and chip disposability cannot be said to be sufficient. Therefore, in the initial stage of lateral feeding, chips tend to come into contact with the machined end face after groove processing and damage the end face, which tends to cause a decrease in the machined surface roughness. In particular, in a cutting insert where the width of the rake face is small and the cutting amount is relatively large and the post-grinding process is performed, the cutting resistance is high and the chips flowing out from the transverse cutting edge at right angles to the cutting insert are clogged. There was a problem in chip disposability, such as the fact that it tends to occur and that the cutting edge is likely to break.

The present invention has been made focusing on such a problem, and provides a cutting insert capable of improving the chip controllability even under machining conditions in which the cutting amount is relatively large in the post-grinding process. The purpose is.

The first invention for solving the above-mentioned problems is a cutting insert used for post-grinding, which performs grooving by vertical feed of a cutting tool and then outer diameter machining by horizontal feed in turning.
A front cutting edge having a rake surface, a front flank surface, and a lateral flank surface connected to the front flank surface, and having a cutting edge at an intersection ridge line between the rake surface and the front flank surface, and the rake surface and outer diameter. The lateral cutting edge is provided with a lateral cutting edge having a crossing ridge line with the lateral flank surface on the side responsible for machining, and the cutting edge of the lateral cutting edge widens the lateral width of the rake face from one end of the cutting edge of the front cutting edge. It is formed so as to extend diagonally backward.
A breaker groove extending rearward from the front cutting edge is formed on the rake surface, and the groove surface of the breaker groove is formed from the cutting edge of the lateral cutting edge in a cross section perpendicular to the crossed ridge line of the lateral cutting edge. The farther away, the lower the downward slope surface is, and the lowest groove surface is formed. In a cutting insert formed to have
The ascending inclined surface is a cutting insert characterized in that the vertical cross section is formed so that the inclination angle becomes smaller toward the rear end from the tip end to the rear end of the cross-cutting blade.

The second invention for solving the above-mentioned problems is when the angle formed by the cutting edge of the horizontal cutting edge and the virtual straight line drawn in the vertical feed direction when the rake face is viewed from above is defined as the horizontal cutting edge angle. ,
The horizontal cutting edge includes a first horizontal cutting edge extending diagonally backward from one end of the cutting edge of the front cutting edge, and a horizontal cutting edge angle α1 of the first horizontal cutting edge from the rear end of the cutting edge of the first horizontal cutting edge. It has a second lateral cutting edge that extends diagonally backwards with different lateral cutting edge angles α2.
The cutting insert according to claim 1, wherein α1 and α2 are formed in a relationship of α1> α2.

A third invention for solving the above-mentioned problems is an edge of the rake face located on the opposite side of the lateral cutting edge, and an edge side which is an intersection ridge line between the lateral flank surface and the rake face on the edge side. The cutting insert according to claim 1 or 2, wherein the ascending inclined surface in the breaker groove is formed so that the flat top surface does not exist in the portion along the crossed ridge line. be.

In the present invention, since it has the above-mentioned configuration, in the post-grinding process after grooving with a large depth of cut, it is cut by a transverse cutting edge, flows along the downward slope of the groove surface of the breaker groove, and then rises. The chips that are pressed against the surface and discharged are subjected to the following deformations and discharged. That is, in the width direction of the cross section of the chip, the portion discharged from the tip side (the inner side of the groove) of the cross cutting blade has a relatively narrow width of the rake face and becomes a steep ascending slope surface. Because it is pressed, it is relatively strong and is greatly bent and deformed. On the other hand, in the width direction of the cross section of the chips, the portion discharged from the rear end side of the cross cutting blade has a relatively wide width of the rake face and is pressed against the gently sloping ascending surface. It is relatively weak and is slightly bent and deformed.

As described above, the chips cut and discharged by the transverse cutting edge in the post-grinding process by the cutting insert of the present invention are deformed in the width direction of the cross section (the tip-rear direction of the transverse cutting edge). For this reason, in machining a work in which chips are extended and discharged in a spiral shape, the portion of the chips cut on the tip side (inner side of the groove) of the transverse cutting edge is relative. Since the curl has a small diameter, even if the distance from the lateral cutting edge to the processed end face (processed wall surface in grooving) is small, the movement does not come into contact with the processed end face. Contact with chips and the occurrence of scratches due to the contact are prevented. On the other hand, among the chips, the portion cut on the rear end side of the transverse cutting edge not at the back of the groove is relatively weak and has a small bending deformation, which contributes to the reduction of cutting resistance. As described above, according to the cutting insert of the present invention, the deformation of the portion in the width direction of the chips generated in the post-grinding process can be controlled, and the discharge direction and the cutting resistance can be controlled. Therefore, even in the post-grinding process in which the cutting amount is relatively large, the chip discharge processability is improved. As a result, it is possible to prevent chip clogging and chipping of the cutting edge.

In the cutting insert of the present invention, the inclination angle of the ascending inclined surface (inclined surface facing the transverse cutting edge) in the vertical cross section is, for example, about 30 degrees near the tip of the transverse cutting edge and 20 degrees near the rear end of the transverse cutting edge. It may be set so that preferable chip discharge treatability can be obtained according to the processing conditions such as the material of the work and the depth of cut (grooving depth) so as to gradually reduce the amount. This tilt angle is an angle with respect to a reference plane (a plane having a rake angle of zero) in setting the rake angle. The edge of the rake face located on the opposite side of the lateral cutting edge may be formed so as to extend rearward from the other end of the front cutting edge according to the grooving process when the rake face is viewed from above. .. However, it is advisable to provide a small rake angle so as to move backward and away from the wall surface so as not to interfere (contact) with the machined wall surface during grooving. On the other hand, the inclination angle of the downward inclined surface (inclined surface facing the opposite side to the lateral cutting edge) is a lateral rake angle (positive rake angle). The inclination angle of the downward inclined surface may be constant or may be changed over the entire length of the transverse cutting edge. It may be appropriately set in consideration of the strength, machinability, sharpness, etc. of the work (work material). Further, the breaker groove may be an arc formed by the entire breaker groove having a concave shape or a V-shaped groove shape in a vertical cross section with respect to the cross ridge line of the transverse cutting edge.

In the second invention, the lateral cutting edge of the cutting insert is set to two steps, the lateral cutting edge angle of the first lateral cutting edge (hereinafter, the first lateral cutting edge angle) α1 and the lateral cutting edge angle of the second lateral cutting edge (hereinafter, the second lateral cutting edge). Blade angle) α2 is assumed to have a relationship of α1> α2. Therefore, a wider rake face (area) can be secured as compared with the case where the horizontal cutting edge is one step (the horizontal cutting edge angle is constant). In addition, it is possible to increase the degree of freedom in the width direction deformation of chips and the adjustment range in the discharge direction when cutting with the entire horizontal cutting edge (first and second horizontal cutting edges). In a small cutting insert with a narrow rake face, the total length of the horizontal cutting edge can be secured longer than that of a one-stage horizontal cutting edge even if the maximum cutting amount is the same, and the cutting generated by cutting with the first horizontal cutting edge can be secured. Since the thickness of the chips can be made relatively thinner than the thickness of the chips generated by cutting with the second transverse cutting edge, the cutting resistance can be reduced even in cutting with a large cutting amount (deep cutting).

In addition, when turning with an automatic lathe that automatically feeds (horizontally feeds) the work material, the cutting tool is fixed to the tool post located in the immediate vicinity of the chuck, and cutting is performed with the cutting edge of the cutting insert. However, in the outer diameter machining of a small diameter shaft member having a diameter of, for example, 6 mm or less, there is a problem that the machining accuracy is lowered due to the bending deformation of the work due to the cutting resistance (back component force). In order to prevent this, the width of the rake face of the cutting insert should be reduced, but in a cutting insert with one horizontal cutting edge (horizontal cutting edge angle), the discharge direction of chips cut by the horizontal cutting edge is It is basically constant, and clogging of chips is likely to occur in deep cutting. On the other hand, in the second invention, even if the width of the cutting insert (horizontal width of the rake face) is the same, the discharge direction and thickness of the chips cut by the horizontal cutting edge are set by the first horizontal cutting edge and the second horizontal cutting edge. Since it can be changed, it is possible to prevent the occurrence of clogging and also to prevent the processing accuracy from deteriorating. Strictly speaking, the cutting edge of the lateral cutting edge may be rounded rather than straight when the rake surface is viewed from above or from the lateral flank surface side.

In the present invention, the rake face may have a flat top surface at a portion along the edge-side crossing ridge line, but as in the third invention, such a top surface does not exist. By assuming that the ascending inclined surface in the breaker groove is formed, it is possible to secure a long inclined length of the ascending inclined surface (inclined surface facing the lateral cutting edge). That is, by setting the top of the ascending inclined surface as the edge of the rake surface located on the opposite side of the lateral cutting edge, the inclined length of the ascending inclined surface (inclined surface facing the lateral cutting edge) can be maximized. Since the degree of freedom of the inclination angle is also increased, the degree of freedom of controlling the deformation and outflow direction of chips can be increased.

In the explanatory view of the first embodiment which embodies the cutting insert of the present invention, A is a view of the lateral cutting edge responsible for outer diameter machining from the lateral flank side, and B is a view from the rake surface side. C is the left side view of A (viewed from the front flank side), and D is the rear view of A. The shape and structure of the cutting insert in FIG. 1 are explained. The right figure is a perspective view of C in FIG. 1 viewed from the upper right and an enlarged view of the main part thereof, and the left figure is a perspective view of C in FIG. 1 viewed from the upper left. Enlarged view of the figure and its main parts. A is an enlarged view of the cutting edge portion of FIG. 1-A, B is an enlarged view of the cutting edge portion of FIG. 1-B, C is an enlarged view of the cutting edge portion of FIG. 1-C, and D is a cutting edge portion of FIG. 1-D. Enlarged view of the blade part. An enlarged view of FIG. 3-B (rake surface). FIG. 4 is a vertical cross-sectional view (AA cross-sectional view to EE cross-sectional view) of each portion of the lateral cutting edge (blade edge) in FIG. An explanatory view of the positional relationship with the work as seen from the cross-cutting blade side of a cutting tool in which the cutting insert of FIG. 1 is fixed to the pocket at the tip of the holder and used as a cutting tool. It is a schematic diagram for explanation that the cutting tool of FIG. 6 is fixed to the tool post (not shown) of the automatic lathe and the post-grinding process is performed. The figure during grooving) and C is the figure during lateral feed (outer diameter machining). An enlarged view seen from the rake face side during outer diameter processing, and a view explaining the flow direction of chips. Of the vertical cross-sectional views of FIG. 5, in the cross-sectional view AA and the cross-sectional view E-E, a diagram illustrating a deformed state when chips flow on a rake face. In the explanatory view of the second embodiment which embodies the cutting insert of the present invention, A is a view of the lateral cutting edge which is responsible for the outer diameter machining from the lateral flank side, and B is the view from the rake surface side. C is the left side view of A (viewed from the front flank side), and D is the rear view of A. The shape and structure of the cutting insert of FIG. 10 are explained. The right figure is a perspective view of C in FIG. 1 viewed from the upper right and an enlarged view of the main part thereof, and the left figure is a perspective view of C in FIG. 1 viewed from the upper left. Enlarged view of the figure and its main parts. A is an enlarged view of the cutting edge portion of FIG. 10-A, B is an enlarged view of the cutting edge portion of FIG. 10-B, C is an enlarged view of the cutting edge portion of FIG. 10-C, and D is a cutting edge portion of FIG. 10-D. Enlarged view of the blade part. An enlarged view of FIG. 12-B (rake surface). FIG. 13 is a vertical cross-sectional view (AA cross-sectional view to EE cross-sectional view) of each portion of the cross-cutting blade (blade edge) in FIG.

An embodiment-1 in which the cutting insert of the present invention is embodied will be described in detail with reference to FIGS. 1 to 9. The cutting insert 100 of this example is formed as a triangular tip based on an equilateral triangular plate having a constant thickness. The cutting edge 200 is formed so that the rake face 120 exists at the corner-side portion of the outer peripheral surface 110 of the triangular tip. The cutting edge 200 is provided on each of the three corners 100c with the same size, shape, and structure, and has three rotational symmetries (120 degrees) around the central axis of a triangle (polygon) ((120 degrees). See Figure 1-A, etc.). Therefore, the following will be described based on the shape and structure of the portion including one cutting edge 200 (upper left cutting edge 200 in FIG. 1-A) in one corner 100c. However, the cutting edge 200 cuts about half of the plate thickness on one surface (upper surface in FIG. 1-B) of the triangular plate at each corner of the triangular plate so as to correspond to the grooving width and the cutting amount. It is notched and cut in a concave shape, and is formed as described in detail below so as to relatively protrude as a thin-walled cutting edge forming portion 105 from the cut plane 107 on the peripheral surface side. At the center of the triangular plate, a hole (circular hole) 109 for attaching to the clamp portion of the holder (shank) serving as a cutting tool by clamping the cutting insert 100 is formed through.

In the cutting edge 200, in the cutting edge forming portion 105 on the upper left of FIG. 1-A, the upper surface portion of the outer peripheral surface 110 of the triangle near the corner 100c is slightly cut out substantially parallel to the side of the triangle (outer peripheral surface 110). , The rake face 120 is formed. The cutting edge 200 of this example has a right triangle having a tip of about 30 degrees when the rake face 120 is viewed from above (see FIGS. 1-B, 3-B, etc.). In this example, the width (horizontal width) W of the cutting edge 200 when the rake face 120 is viewed from above is about 1.5 mm, and the tip (left end in FIG. 3) has a minute width. The front cutting edge 210 (for example, having a length of 0.4 to 0.5 mm) is formed with the crossing ridge line of the rake face 120 and the front flank surface 130 as the cutting edge 210a. When the rake face 120 is viewed from above, the front cutting edge 210 is raked diagonally backward (lower right in FIG. 3-B) from one end (lower end of FIG. 3-B) P1 of the front cutting edge 210. A horizontal cutting edge 220 extending at a predetermined horizontal cutting edge angle α (about 30 degrees in the drawing) with respect to a virtual straight line L1 drawn in the vertical feed direction so as to widen the horizontal width of the surface 120 (vertical width in FIG. 3-B) is provided. .. As a result, the lateral cutting edge 220 uses the intersecting ridge line 220a between the rake surface 120 and the lateral flank surface 140 as the cutting edge (blade edge 220a). In this example, the heights of the cutting edges of the front cutting edge 210 and the lateral cutting edge 220 are not exactly the same, but are set so as to be approximately located on one virtual plane. The front cutting edge 210 is when the rake face 120 is viewed from above so that the other end (upper end of FIG. 3-B) P2 is located at the most advanced end (leftmost end of FIG. 3-B) during vertical feed. , It is assumed that a minute inclination angle (1 to 2 degrees) is attached to the rotation axis of the work.

On the other hand, of the rake face 120, the edge 250 on the side opposite to the lateral cutting edge 220 (upper side in FIG. 3-B) extends rearward from the other end P2 of the front cutting edge 210 in a substantially straight line. The edge 250 forms an edge-side crossing ridge line 250a, which is a crossing ridge line between the rake face 120 and the lateral flank 150 on the edge 250 side. When the rake face 120 is viewed from above, the opposite end edge (and its lateral flank) 250 is back raked so as not to contact or interfere with the wall surface of the groove during vertical feeding (grooving). It has a corner (1-2 degrees). When the rake face 120 is viewed from above, a fine radius (for example, R0.1) is attached to the angle (corner P2) formed by the front cutting edge 210 and the edge side crossing ridge line 250a. That is, the other end (upper end of FIG. 3-B) P2 of the front cutting edge 210 is provided with a minute radius. Further, an appropriate clearance angle is provided to the rake face 120 and each flank (front flank 130, lateral flank 140, 150) forming each cutting edge (front cutting edge 210 and lateral cutting edge 220). So, for example, it is cut and formed on a flat surface.

Next, the structure of the rake face 120 will be described in detail (see the enlarged view of FIG. 2, FIG. 3-B, FIG. 4, and FIG. 5). A breaker groove 170 extending rearward from the front cutting edge 210 is formed on the rake face 120. This breaker groove 170 is slightly formed at the intermediate portion between the cutting edge of the cross-cutting blade 220 (crossing ridge line 220a) and the edge opposite to the cross-cutting blade 220 (edge-edge side crossing ridge line 250a), and the cutting edge of the cross-cutting blade 220 (crossing ridge line). 220a) It becomes a concave groove having a minimum groove surface 175 near the side and extends rearward. The groove surface becomes lower in the vertical cross section of the cross-cutting blade 220 with respect to the crossed ridge line 220a (see FIGS. 4 and 5) as the distance from the cutting edge of the cross-cutting blade 220 (crossing ridge line 220a) increases, and a positive rake angle is provided. It has a downwardly inclined surface 173 and becomes the lowest groove surface 175, and faces the end edge (end edge side crossing ridge line 250a) of the rake face 120 located on the opposite side to the lateral cutting edge 220 through the lowest groove surface 175. It has an ascending inclined surface 177 forming a high position, and is formed so that the lengths of the descending inclined surface 173 and the ascending inclined surface 177 in the vertical cross section become longer toward the rear of the groove. The rake angle (horizontal rake angle) of the lateral cutting edge 220 may change after that, but in this example, it is constant (or in the range of 14 to 20 degrees) at, for example, 15 degrees. Further, the front cutting edge 210 is also formed so as to be provided with the same rake angle, but these are set appropriately in consideration of sharpness, cutting edge strength and the like.

On the other hand, the inclination angle of the ascending inclined surface 177 that rises from the lowest groove surface 175 toward the edge 250a of the rake surface 120 located on the opposite side of the lateral cutting edge 220 is the vertical cross section of the lateral cutting edge 220 with respect to the cross ridge line 220a. (AA cross section to EE cross section) in FIG. 4), it is set to gradually decrease toward the rear end from the tip P1 of the transverse cutting edge 220 (see FIG. 5). That is, the inclination angles of the ascending inclined surface 177 in each of the cross sections (AA cross section, BB cross section, CC cross section, DD cross section, EE cross section) are shown in FIG. Although it is indicated by θb, θc, θd, and θe, it is set to gradually decrease in that order, and is formed to have a gentle gradient. As a specific example, the AA cross section near the front cutting edge 210 has a gentle gradient of about 23 degrees, and the AA cross section gradually decreases toward the rear end of the lateral cutting edge 220, and the EE cross section has a gentle gradient of about 23 degrees. It is set to be. As described above, in the vertical cross section of the cross cutting blade 220 with respect to the cross ridge line 220a (AA cross section to EE cross section in FIG. 4), the rake including the ascending inclined surface 177 is directed toward the rear end from the tip P1 of the cross cutting blade 220. The width of the surface is widened, and the ascending inclined surface 177 is formed so as to have a long length and a gentle slope.

On the edge 250 side opposite to the cross-cutting blade 220, along the edge-side crossing ridge line 250a, for example, above the broken line H in FIG. 4, the portion closer to the edge 250 is flattened. A flat surface (flat top surface) may be provided between the upper end (top) of the ascending inclined surface 177 and the edge 250, but in this example, the edge 250 is provided without providing such a flat surface. However, as shown in each cross section of FIG. 5, the breaker groove 170 has an acute angle and a substantially entire rake face 120 is recessed. That is, in this example, the breaker groove 170 is the edge side crossing ridge line which is an edge located on the opposite side of the rake face 120, the cutting edge 210a of the front cutting edge 210, the cutting edge 220a of the lateral cutting edge 220, and the lateral cutting edge 220. It is formed in a concave shape so that substantially the entire rake face 120 becomes a groove surface, leaving 250a.

As described above, the cross-cutting blade 220 has the cutting edge 220a having substantially the same height at the tip and the back, and the rake angle (horizontal rake angle) is also the same, but strictly speaking, the intermediate portion is set to be slightly lower. (See Fig. 3-A). On the other hand, the end edge side crossing ridge line 250a (the end edge of the rake face 120) opposite to the lateral cutting edge 220 has substantially the same height as the tips of the front cutting edge 210 and the lateral cutting edge 220 at the tip, and has a gentle gradient within a predetermined range. It has an inclined portion of the above, is slightly higher than the lateral cutting edge 220 (0.2 to 0.3 mm), and extends rearward at a constant height through this inclined portion (see FIGS. 3-A and D).

As shown in FIG. 6, such a cutting insert 100 of this example is vertically arranged and fixed to a holder 10 having a clamp portion (pocket) at the tip for clamping (fixing) the cutting insert 100. It becomes a cutting tool 20, and is used for cutting (post-grinding) of the work 30 in the same manner as in the conventional case. Here, the processing will be briefly described with reference to FIG. 7. The cutting tool 20 is fixed to a tool post (not shown) arranged in front of the chuck 40 of the automatic lathe as shown in FIG. 7-A. In cutting, as shown in FIG. 7-B, the cutting tool 20 is vertically fed by a predetermined amount toward the work (round bar) 30 fixed to the rotating chuck 40 (in the direction orthogonal to the rotation axis). Then cut and grooving. In this grooving process, a back rake angle (1 to 2 degrees) is attached to the end edge (end edge side crossing ridge line 250a) opposite to the lateral cutting edge 220 extending rearward from the other end P2 of the front cutting edge 210. , The opposite edge does not touch the wall surface of the groove (processed wall surface). After the predetermined longitudinal feed, as shown in FIG. 7-C, the cutting tool 20 is laterally fed (the work 30 is laterally fed in a lathe with an automatic lateral feed device) at a predetermined speed, and the groove is formed. Post-grinding (outer diameter processing) is performed over a predetermined range in the direction away from the processed wall surface (flange).

In the case where the work (round bar of SUS404) having a diameter of 10 mm is post-ground to φ6 using the cutting insert 100 of this example (cutting speed: 30 m / min), Comparative Example 1 and Comparative Example 2 The cutting insert of No. 1 showed an improvement in the accuracy of the machined surface (finished surface) compared to the case of post-grinding under the same conditions. From this, it was demonstrated that the chip controllability was improved in the post-grinding process using the cutting insert 100 of this example. In the cutting insert of Comparative Example 1, the "upward inclined surface 177" of this example was made constant at 28 degrees or 23 degrees from the position near the front cutting edge 210 toward the rear end of the lateral cutting edge 220. Two were used. Further, the cutting insert of Comparative Example 2 is a cutting insert of Comparative Example 1 in which a breaker groove is formed by imitating the cutting insert described in Document 1. It is considered that preferable chip controllability can be obtained by the post-grinding process using the cutting insert 100 of this example (see FIGS. 8 and 9).

As shown in FIG. 8, the chip K generated in the post-grinding process is basically a width corresponding to the length Lh of the cutting edge responsible for cutting the lateral cutting edge 220, and a thickness Ta corresponding to the lateral feed amount. (See the hatched portion in FIG. 8), when the rake face 120 is viewed from above, it flows out in a direction perpendicular to the cutting edge (crossing ridge line) of the cross-cutting blade 220 as shown by the broken line arrow. The chips K flowing through the rake face 120 in this way are pressed against the uphill inclined surface 177 from the downhill inclined surface 173 of the breaker groove 170, deformed and discharged. On the other hand, as shown in the upper view (AA cross section) of FIG. 9, the tip side of the lateral cutting edge 220 has a relatively wider width of the rake face 120 as compared with the lower figure (EE cross section) of FIG. It is narrow and the uphill slope 177 is steep. Therefore, of the length Lh in the width direction of the cross section of the chip, the portion discharged from the tip side (the back side of the groove) of the cross cutting blade 220 has a narrow width of the rake face 120 and a steep slope. Because it is pressed against the ascending inclined surface 177, the discharge is controlled so as to be relatively strong and greatly bent and deformed (upper view (AA cross section) in FIG. 9). On the other hand, of the length Lh in the width direction of the cross section of the chip, the portion discharged from the rear end side of the cross cutting blade 220 has a wide width of the rake face 120 and is pressed against the gently sloping ascending surface 177. The discharge is controlled so that it is relatively weak and is slightly bent and deformed (lower figure (EE cross section) in FIG. 9).

That is, among the chips generated in the post-grinding process, the chip portion generated by cutting on the tip side of the transverse cutting edge 220 in the width direction (length Lh direction) of the cross section is a relatively rake surface 120. The width is narrow and the steep ascending slope 177 transforms it into a curl with a small diameter, so even if the distance to the machined end face (processed wall surface in grooving) is small, contact with the machined end face Flow to prevent the occurrence of. On the other hand, the chip portion generated by cutting on the rear end side of the lateral cutting edge 220 has a relatively wide lateral width of the rake face 120, and has a relatively large diameter due to curl deformation due to the gently sloping ascending inclined surface 177. Therefore, it does not cause an increase in cutting resistance. As described above, the chip K undergoes different deformation actions on one end side (groove bottom side) and the other end side in the length Lh portion in the width direction. As a result, it is possible to prevent the occurrence of scratches due to the chip K coming into contact with the processed end face, and also to prevent the chips from being clogged or entangled. As described above, according to the cutting insert 100 of this example, the discharge direction and the cutting resistance can be controlled in the width direction portion of the chips generated in the post-grinding process, so that the chip discharge processability is improved and the finished surface accuracy is improved. Is enhanced.

Further, as described above, the rake face 120 may have a flat top surface at a portion along the edge-side crossing ridge line 250, but in this example, such a top surface does not exist. As described above, the ascending inclined surface 177 in the breaker groove 170 is formed. That is, in this example, the edge 250 located on the opposite side to the lateral cutting edge 220 forms an acute angle (acute angle) as shown in each cross section of FIG. 5, and only the edge side crossing ridge line 250a which is the edge is formed. Remaining, the rake face 120 is formed in a concave shape so that substantially the entire surface becomes a groove surface. Therefore, the inclination length of the ascending inclined surface 177 can be secured to be long, and the degree of freedom of the inclination angle is also increased, so that the degree of freedom of controlling the deformation of chips and the outflow direction can be increased.

Next, another embodiment example-2 in which the cutting insert embodying the present invention is embodied will be described with reference to FIGS. 10 to 14. However, the cutting insert 102 of this example is not essentially different from that of the above-described first embodiment, and the protruding length of the cutting edge forming portion 105 and the width thereof when the rake face 120 is viewed from above. W is the same, and it can be said that the only difference is that the horizontal cutting edge 220 is a two-stage horizontal cutting edge. That is, in this example, the lateral cutting edge 220 has a first lateral cutting edge angle α1 = 40 degrees from one end P1 of the cutting edge 210a of the front cutting edge 210 when the cutting edge of the cutting edge 120 is viewed from above. The first horizontal cutting blade 221 extending diagonally backward to a substantially intermediate position of the total length (front and rear length) of the horizontal cutting blade 220, and the second horizontal cutting blade from the rear end P3 of the cutting edge 221a of the first horizontal cutting blade 221. It has a second lateral cutting edge 222 that extends linearly toward the rear diagonally at an angle α2 = 20 degrees. Only the difference from the one set to 30 degrees (constant) and the difference in the shape of the rake face 120 based on the difference are different. Therefore, this difference will be mainly described, and the same reference numerals will be given to the parts common to the previous example, and the description thereof will be omitted as appropriate.

That is, in the cutting insert 102 of this example, when the lateral cutting edge 220 is two steps and the rake face 120 is viewed from above (see FIG. 13), the lateral cutting edge angle of the first lateral cutting edge 221 is set to the first lateral cutting edge angle α1. = 40 degrees, and the lateral cutting edge angle of the second lateral cutting edge 222 is set to the second lateral cutting edge angle α2 = 20 degrees, and the relationship of α1> α2 is assumed. When the rake face 120 is viewed from above, the width W thereof is the same as that in the previous example, and the lengths of the first horizontal cutting blade 221 and the second horizontal cutting blade 222 are substantially the same, α1 = 40 degrees. Since α2 = 20 degrees, the width between the front and back of the rake face 120 is wider in this example than in the previous example.

A breaker groove 170 extending rearward from the front cutting edge 210 is also formed on the rake face 120 of the cutting insert 102 of this example. The groove surface is lower as it is farther from the cutting edge of the horizontal cutting blade 220 in the vertical cross section of the first horizontal cutting blade 221 and the second horizontal cutting blade 222 (also referred to as the horizontal cutting blade 220) with respect to the crossing ridges (cutting edges) 221a and 222a. It has a downward sloping surface 173 (given a positive rake angle) and becomes the minimum groove surface 175, and the edge of the rake surface 120 located on the opposite side of the transverse cutting edge 220 via the minimum groove surface 175. It is formed to have an ascending inclined surface 177 that is higher toward 250 (see FIG. 14). However, the lateral width of the rake face 120 is widened so as to be bent at the rear end P3 of the first horizontal cutting edge 221, that is, the intermediate point of the horizontal cutting edge which is the connection point between the first horizontal cutting edge 221 and the second horizontal cutting edge 222. Therefore, the minimum groove surface 175 is located closer to the intermediate position between the crossed ridges 221a and 222a of the lateral cutting edge 220 and the end edge side crossed ridges 250a.

Then, as shown in FIGS. 13 and 14, the ascending inclined surface 177 is also perpendicular to the cross-sectional ridges 221a and 222a of the first horizontal cutting blade 221 and the second horizontal cutting blade 222 toward the rear end from the tip of the horizontal cutting blade 220. In the cross section (see the AA cross section to the EE cross section of FIG. 14), the inclination angle is formed so as to gradually decrease. Specifically, in the cross section perpendicular to the cutting edge (intersection ridge line 221a between the rake face 120 and the flank surface 140) in the first horizontal cutting blade 221, the degree is gradually reduced from 28 degrees to about 24 degrees, and the second horizontal cutting blade 222. In the cross section perpendicular to the cutting edge (crossing ridge line 222a between the rake face 120 and the flank surface 140), the angle is set to gradually decrease from 24 degrees to about 23 degrees in the order of angles θa, θb, θc, θd, and θe. ing.

However, the cutting insert 102 of this example is also fixed to the holder as in the previous example to become a cutting tool and used for post-grinding, but in that case, the same effect as that of the above example is obtained. Be done. Moreover, even if the width W of the rake face 120 when viewed from above is the same, in the cutting insert 102 of this example, the lateral cutting edge 220 has a first lateral cutting edge angle α1 = 40 degrees and a second lateral cutting edge angle α2 = 20. Since the horizontal cutting edge 220 has two stages, the following unique effects can be obtained.

That is, the horizontal cutting edge 220 has one horizontal cutting edge angle (α = 30 degrees) in the previous example, whereas in this example, it is a two-stage horizontal cutting edge 220 (221,222) as described above. Therefore, the downward inclined surface 173 corresponding to the rake angle in the cross section perpendicular to the crossed ridge line of the lateral cutting edge 220 and the ascending inclined surface that becomes higher as the distance from the cutting edge of the lateral cutting edge 220 toward the side opposite to the lateral cutting edge 220. A large amount of each length of 177 can be secured. Therefore, the degree of freedom in controlling the flow direction of the chips flowing perpendicularly to the lateral cutting edge 220 on the rake face 120 is increased.

Moreover, in this example, the lateral cutting edge angle is the two-stage lateral cutting edge 220 that bends in a clearly different shape at the connection point P3 between the first lateral cutting edge 221 and the second lateral cutting edge 222. The chips generated when the outer diameter is machined by laterally feeding with a deep cut up to the transverse cutting edge 222 can be positively deformed so as to bend the transverse cross section after the connection point P3. Further, since the first horizontal cutting edge 221 has a larger horizontal cutting edge angle than the second horizontal cutting edge 222, the thickness of the chips can be reduced. As a result, cutting resistance can be reduced even in deep cutting, and chip clogging can be prevented. Since the first lateral cutting edge angle α1 is larger than the lateral cutting edge angle α in the precedent, chips can be discharged more backward at the portion closer to the tip in the width direction. That is, even if the deep cut is laterally fed, the portion of the chip cut at the portion of the first lateral cutting blade 221 is cut by the second lateral cutting blade 222, and the chip flowing toward the processed wall surface is moved backward. A guiding action is obtained. Therefore, in addition to reducing the cutting resistance, the action of preventing the entire chip from coming into contact with the machined wall surface is further enhanced. Therefore, in the case of lateral feeding in deep cutting, the chip dispersibility at the start of lateral feeding and immediately after the start can be further improved.

In addition, since the cutting resistance is reduced as well as the chip dispersibility in this way, the work is bent and deformed even in the post-grinding of small items (small diameter workpieces) by an automatic lathe that automatically feeds (horizontally feeds) the work material. It also contributes to solving the problem of deterioration of processing accuracy due to the occurrence of. The shape of the horizontal cutting blade 220 when the rake face 120 is viewed from above may be a three-stage horizontal cutting blade (first to third horizontal cutting blades) in which the horizontal cutting blade angles are sequentially reduced. It may be 4 steps or more. Further, the cutting edge of the lateral cutting edge when the rake face is viewed from above may have a rounded shape instead of a straight line regardless of the number of steps.

In this example as well, a flat surface (flat top surface) as described above may be provided along the edge-side crossing ridge line 250a on the end edge 250 side opposite to the cross-cutting blade 220. Then, the entire rake face 120 is recessed as the breaker groove 170 without providing such a flat surface. Therefore, the degree of freedom in setting the length of the ascending inclined surface can be increased, and the degree of freedom in controlling the discharge of chips can be further increased.

The present invention is not limited to the one described in each of the above-described embodiments, and can be appropriately modified and embodied without departing from the gist thereof. For example, the degree of change in which the inclination angle (angle) of the ascending inclined surface gradually decreases from the tip to the rear, or the number of steps of the lateral cutting edge angle can be appropriately changed and embodied. Further, the lateral rake angle may be appropriately set in consideration of the strength, sharpness, etc. of the work material as described above, and the angle may also be changed after the tip of the lateral cutting edge. A land may be attached to the cutting edge. Further, the height of the lateral cutting edge and the height of the edge opposite to the lateral cutting edge may also be changed before and after. In the above example, a cutting insert formed based on a triangular tip having three cutting edges is exemplified, but as a cutting insert having a square tip having four cutting edges or a tip having only one cutting edge. It can also be materialized.

100, 102 Cutting insert 120 Flake surface 130 Front flank surface 140 Lateral flank surface on the side responsible for outer diameter machining 150 Lateral flank surface 150 on the edge side Ridge line 170 Breaker groove 173 Downward inclined surface of breaker groove 175 Minimum groove surface of breaker groove 177 Upward inclined surface of breaker groove 210 Front cutting edge 220 Horizontal cutting edge 220a, 221a, 222a Crossed ridgeline of horizontal cutting edge (edge of horizontal cutting edge)
221 1st lateral cutting edge 222 2nd lateral cutting edge 250 Edge edge of rake face located on the opposite side of the lateral cutting edge 250a Edge edge side crossing ridge line P1 One end of the cutting edge of the front cutting edge θa to θe Inclination angle L1 of the ascending inclined surface Virtual straight line drawn in the feed direction α Horizontal cutting edge angle α1 1st horizontal cutting edge angle α2 2nd horizontal cutting edge angle

Claims (3)

It is a cutting insert used for post-grinding that performs grooving by vertical feed of cutting tools and then outer diameter machining by horizontal feed in turning.
A front cutting edge having a rake surface, a front flank surface, and a lateral flank surface connected to the front flank surface, and having a cutting edge at an intersection ridge line between the rake surface and the front flank surface, and the rake surface and outer diameter. The lateral cutting edge is provided with a lateral cutting edge having a crossing ridge line with the lateral flank surface on the side responsible for machining, and the cutting edge of the lateral cutting edge widens the lateral width of the rake face from one end of the cutting edge of the front cutting edge. It is formed so as to extend diagonally backward.
A breaker groove extending rearward from the front cutting edge is formed on the rake surface, and the groove surface of the breaker groove is formed from the cutting edge of the lateral cutting edge in a cross section perpendicular to the crossed ridge line of the lateral cutting edge. The farther away, the lower the downward slope surface is, and the lowest groove surface is formed. In a cutting insert formed to have
The cutting insert is characterized in that the ascending inclined surface is formed so that the vertical cross section has a gentle inclination with a smaller inclination angle from the tip end to the rear end of the cross-cutting blade. When the angle formed by the cutting edge of the horizontal cutting edge and the virtual straight line drawn in the vertical feed direction when the rake face is viewed from above is defined as the horizontal cutting edge angle.
The horizontal cutting edge includes a first horizontal cutting edge extending diagonally backward from one end of the cutting edge of the front cutting edge, and a horizontal cutting edge angle α1 of the first horizontal cutting edge from the rear end of the cutting edge of the first horizontal cutting edge. It has a second lateral cutting edge that extends diagonally backwards with different lateral cutting edge angles α2.
The cutting insert according to claim 1, wherein α1 and α2 are formed so as to have a relationship of α1> α2. There is no flat top surface at the edge of the rake face located on the opposite side of the cross-cutting edge, and along the edge-side crossing ridge, which is the crossing ridge between the lateral flank and the rake on the edge side. The cutting insert according to any one of claims 1 or 2, wherein the ascending inclined surface in the breaker groove is formed.

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