JP2007319986A - Throw-away rotary tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a throw-away rotary tool, performing machining under a high cutting condition by heightening the rigidity of a tool body and a tip especially in a small-diameter throw-away rotary tool. <P>SOLUTION: In this throw-away rotary tool 1, a substantially plate-like tip 30 including cutting edges 31A, 31B is inserted in a fitting groove 20 of the tool body 10, and pressed by screw members 40A, 40B to be fixed. The wall surface side of the fitting groove 20 facing the top face 30a of the tip is provided with female screw holes 13A, 13B where the screw members 40A, 40B are screwed, and the top face 30a of the tip is provided with recessed parts 35A, 35B having bases pressed to the screw members 40A, 40B. The perpendiculars P of the bases of the recessed parts and the central axes CLs of the female screw holes are gradually inclined to approach constrained surfaces 37, 38 formed on the side pointing the tool inner peripheral side or the side pointing the tool base end side as they approach a seating surface 34 opposite to the top face of the tip 30. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a throw-away rotary tool such as a milling cutter, an end mill, a drill, a boring cutter, and a reamer, and particularly to a technique for improving the tool rigidity and cutting performance of a throw-away rotary tool having a small outer peripheral cutting edge diameter.

  Known techniques relating to this type of throw-away rotary tool are illustrated in FIGS. The cutting insert shown in FIG. 7 has a parallelepipedal basic shape, and is attached to a milling body to be rotated by a milling machine. The milling body shown in FIG. 8 comprises at least one pocket for receiving a parallelepiped cutting insert. The cutting insert 10 includes complementary side portions 13, 14 and two substantially parallel main side portions 11, 12 that are integral with the upper surface 15 and the lower surface 16. The upper surface 15 forms main cutting edges 17 and 18 at intersection lines with the main side portions 11 and 12. The main cutting edges are inclined in opposite directions because each cutting edge forms an acute angle with respect to the lower surface 16. Thereby they are provided with opposing sides of the cutting insert and increase, but the axial angle is directed in the opposite direction. Each main cutting edge increases the working positive axis angle of the tool when mounted in the cutting insert pocket of the milling body. Furthermore, a top cutting edge or wiper forms 19, 20 with the top surface 15 intersecting at a relatively small part of the respective complementary side 13,13. The main cutting edges 17, 18 and the complementary cutting edges 19, 20 cooperating with each form a pair of cutting edges that operate when another pair is not operating during milling. Two adjacent cutting edges intersect at the area of the cutting corner. The cutting corner defines a bisector that divides the corner into two equal corners. The bisector does not intersect the center of the corner radius. When a pair of cutting edges are worn, the cutting insert is indexed so that another pair of cutting edges is in the working position. The upper surface forms a chip surface in the cutting edge region and forms a cutting edge angle together with the main side portion and the auxiliary side portion, and this angle is smaller than 90 degrees, that is, the cutting insert has a positive basic shape. Further, the chip surface 15 preferably forms a positive rake angle with an increasing tendency to easily cut the workpiece. The lower surface 16 forms an obtuse internal angle together with the cooperating portions of the complementary side portion and the main side portion. A centrally located hole 21 is provided for receiving fastening means such as screws when mounted on the milling body. The milling cutter is preferably mounted on a shoulder milling cutter at a 90-degree corner (see, for example, Patent Document 1).

  The milling tool for rotary chip removal machining shown in FIG. 9 includes a cutting head 10, a holding means 11, and a shank 12, and the cutting head 10 includes at least one cutting edge 27 integral therewith, and the cutting tool The head and the holding means include partially overlapping asymmetric means 15, 19 for attaching the cutting head to the shank, and the tool has an axis of rotation. The cutting head 10 comprises 1 to 6 main cutting edges 27, each main cutting edge 27 being essentially a straight edge 27A and a convexly curved, preferably partially circular edge. 27B, and the convex blade 27B is provided on the radially outer side of the essentially linear blade 27A (see, for example, Patent Document 2).

Special table 2002-524275 gazette Special table 2001-505137

  The milling tool shown in FIGS. 7 and 8 is configured to be attached to the milling body by a screw received in the hole 21 arranged at the center of the cutting insert, and is schematically shown in FIG. 6B. The cross-sectional shape when cut by a plane that passes through the vicinity of the center of the screw and that is perpendicular to the center axis of the milling body is such that when the tool diameter (diameter of the outer peripheral cutting edge) is reduced, the two cutting inserts approach each other. The thickness (core thickness) of the center portion of the milling body is reduced, and the rigidity of the milling body cannot be ensured. On the other hand, when the cutting insert is downsized to solve this problem, the thickness around the hole 21 becomes thin, and the rigidity of the cutting insert cannot be secured. Alternatively, when the working positive shaft angle of the tool is increased, the cross-sectional area of the back metal of the cutting insert pocket in the milling body becomes very small, so that there is a risk that the screw will become shallow and loosen, Since there is a risk of plastic deformation and breakage due to resistance (mainly the main component force), there is a problem that it cannot be used unless the cutting conditions are considerably reduced compared to a solid end mill of the same tool diameter.

  In the milling tool shown in FIG. 9, although the problem of the tool rigidity described above is not large, the shape of the cutting edges 27 and 30 of the cutting head is complicated as the shape of the cutting edge at the tip of the solid end mill or the solid drill, and the holding means Since the shape is also complicated, there is a problem that it is difficult to produce the cutting head and the cost required for the production becomes very high.

  The present invention has been made in order to solve the above-described problem. By increasing the rigidity of the tool main body and the tip, a throw-away rotary tool capable of processing under higher cutting conditions than this type of conventional tool is provided. The purpose is to provide.

In order to solve the above problems, the present invention employs the following means. The invention according to claim 1 is a tool main body (10) rotated around a central axis (CL), and at least one mounting groove (20) formed in a notch on the outer peripheral surface of the tip end of the tool main body (10). And a tip (30) that is detachably attached by a screw member (40A, 40B). The tip (30) is substantially plate-shaped and has a tool rotation direction ( K) the rake face (32A, 32B) formed on the upper surface (30a), the seating surface (34) formed on the lower face (30b) facing the upper face (30a), and the rake face (32A, 32B) is formed on the flank face (33A, 33B) formed on the side surface facing the outer peripheral side of the tool, and at the intersecting ridge line portion of these rake face (32A, 32B) and flank face (33A, 33B), and at least the tool Book Cutting edge (31A, 31B) projecting from an outer peripheral surface (10b) with, restrained surface formed on at least one side surface facing the side surface or the tool base side facing the tool peripheral side (37, 38),
And at least one female screw hole (13A, 13B) into which the screw member (40A, 40B) is screwed is provided on the wall surface side of the mounting groove (20) facing the upper surface (30a) of the chip, At least one recess (35A, 35B) having a bottom surface pressed against the screw member (40A, 40B) is formed on the upper surface (30a) of the chip, and the central axis (CLs) of the female screw hole and the recess The vertical line (P) of the bottom surface of the base plate is inclined so as to gradually approach the restrained surface (37, 38) as the seat surface (34) is approached with respect to the normal line of the seat surface (34). This is a throw-away rotary tool.
The invention according to claim 1 has the following technical effect as compared with the conventional tool shown in FIGS.
Since the screw member that fixes the tip to the tool body does not penetrate the upper and lower surfaces of the tip, it is possible to reduce the size of the tip. The wall thickness is sufficiently secured. Since no female screw hole is required on the mounting surface side on which the chip is seated, the rigidity of the mounting surface is particularly high. From the above, since the bending of the tool body due to the cutting resistance is suppressed to be small, it is possible to perform machining under higher cutting conditions than the conventional tool.
Compared with the conventional tool shown in FIG. 9, the outer shape of the chip and the shape of the cutting edge are not complicated, so that the chip can be manufactured easily and at low cost.
A recess recessed from the top surface of the chip is formed, and the perpendicular of the bottom surface of the recess and the central axis of the screw member are inclined so as to gradually approach the restrained surface as the seating surface is approached, and the screw member is Since the bottom surface of the chip is pressed, the seating surface and the restrained surface of the chip are pressed against the mounting surface and the restraining surface of the mounting groove, respectively, and are firmly clamped in the mounting groove. Therefore, the movement of the chip due to cutting resistance is prevented, and high machining accuracy is realized.

The invention according to claim 2 is the invention according to claim 1, wherein the angle formed by the central axis (CLs) of the female screw hole and the perpendicular (P) of the bottom surface of the recess and the perpendicular of the seating surface (34) is It exists in the range of 5 degrees-20 degrees.
According to the second aspect of the present invention, the angle formed by the perpendicular of the bottom surface of the recess and the central axis of the screw member and the perpendicular of the seating surface is set within a range of 5 ° to 20 °. Clamping performance is even better. The above range is limited because when the angle is less than 5 °, the force for pressing the tip against the restraint surface is insufficient, and when the angle exceeds 20 °, the tip is strongly pressed against the restraint surface and the tip is attached. This is because the tip may move during the cutting process and the processing accuracy may be deteriorated, and the chip may be lost in some cases.

The invention according to claim 3 is the invention according to claim 1 or 2, wherein the cutting edges (31A, 31B) are formed so as to protrude from the tip surface (10a) and the outer peripheral surface (10b) of the tool body, respectively. A cutting edge (31A) and a secondary cutting edge (31B), wherein the length (L) of the outer peripheral cutting edge in the direction of the central axis (CL) of the tool body is at least one time the diameter (D) of the outer peripheral cutting edge; It is characterized by being in the range of 2 times or less.
According to the invention according to claim 3, the throw-away rotary tool of the present invention is a throw-away end mill, and an outer peripheral cutting edge formed so that its cutting edge protrudes from the outer peripheral surface and the tip end surface of the tool body, respectively. A secondary cutting edge is provided, and the length in the central axis direction of the outer peripheral cutting edge is in the range of 1 to 2 times the diameter of the outer peripheral cutting edge of the throw-away end mill. High-efficiency machining with a large depth of cut becomes possible. Furthermore, since the constrained surface and the constraining surface are elongated in the direction of the central axis, the mounting accuracy is further improved.

The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the outer peripheral cutting edge (31A) is a twisting blade having a twist angle (α).
According to the invention according to claim 4, in the throw-away rotary tool according to claim 3, since the outer peripheral cutting edge is a twisted blade, the sharpness at each position of the outer peripheral cutting edge is good and uniform, In high-efficiency machining with a large cut in the central axis direction, cutting resistance acting on the tool body and the insert is reduced.

The invention according to claim 5 is the invention according to claim 4, wherein the torsion angle (α) of the outer peripheral cutting edge is in the range of 10 ° to 20 °, and the outer peripheral rake angle (β) is −5 ° to 15 °. It is in the range of °.
According to the invention which concerns on Claim 5, since the torsion angle of the said outer periphery cutting edge exists in the range of 10 degrees-20 degrees, and the outer periphery rake angle was set in the range of -5 degrees-15 degrees, the outer periphery cutting is further performed. Since the sharpness of the blade is improved and the cutting resistance is reduced, high-efficiency machining with further increased cutting and feeding becomes possible.

The invention according to claim 6 is the invention according to any one of claims 1 to 5, characterized in that a diameter (D) of the outer peripheral cutting edge is in a range of 6 mm to 20 mm.
As in the invention according to claim 6, it is preferable that the diameter of the outer peripheral cutting edge of the throw-away end mill is in the range of 6 mm to 20 mm. This is because the present end mill has a configuration suitable for reducing the size of the chip, and is effective in reducing the diameter of the outer peripheral cutting edge. Regardless of the diameter, it has the effect of increasing the rigidity of the tool body and the tip, but the effect is remarkable in the above-mentioned range.

The present invention has the following technical effects as compared with the conventional tool shown in FIGS.
Since the screw member that fixes the tip to the tool body does not penetrate the upper and lower surfaces of the tip, it is possible to reduce the size of the tip. The wall thickness is sufficiently secured. Since no female screw hole is required on the mounting surface side on which the chip is seated, the rigidity of the mounting surface is particularly high. From the above, since the bending of the tool body due to the cutting resistance is suppressed to be small, it is possible to perform machining under higher cutting conditions than the conventional tool.
Compared with the conventional tool shown in FIG. 9, the outer shape of the chip and the shape of the cutting edge are not complicated, so that the chip can be manufactured easily and at low cost.
A recess recessed from the top surface of the chip is formed, and the perpendicular of the bottom surface of the recess and the central axis of the screw member are inclined so as to gradually approach the restrained surface as the seating surface is approached, and the screw member is Since the bottom surface of the chip is pressed, the seating surface and the restrained surface of the chip are pressed against the mounting surface and the restraining surface of the mounting groove, respectively, and are firmly clamped in the mounting groove. Therefore, the movement of the chip due to cutting resistance is prevented, and high machining accuracy is realized.

Hereinafter, an embodiment of a throw-away rotary tool according to the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a throw-away end mill according to this embodiment. FIG. 2 is an exploded perspective view of the end mill shown in FIG. 3A to 3C are a plan view, a front view, and a front view side view of the end mill shown in FIG. 1, respectively. FIG. 4 is a perspective view of a tip attached to the end mill shown in FIG. 5A to 5E are a rear view, a plan view, a front view, a left side view, and a right side view of the chip shown in FIG. 4 in order. FIG. 6 is a diagram showing a cross-sectional shape cut by a plane perpendicular to the center axis of the end mill at the center of the screw member, and FIG. 6A is a cross-sectional shape of the end mill to which the present invention is applied. (B) is a cross-sectional shape of a conventional tool.

  As shown in FIGS. 1 to 3, in the throw-away end mill 1, a tip 30 having a cutting edge is inserted into two mounting grooves 20 provided on the outer peripheral surface of the tip of a tool body 10 having a substantially round bar shape. It is detachably fixed using two screw members 40A and 40B. The tool main body 10 includes a head portion 10A formed on the tool distal end side, and a slightly larger shank portion 10B formed on the tool base end portion side in connection with the head portion 10A. Furthermore, an attachment groove 20 extending from the distal end surface 10 a to the tool proximal end side is formed substantially symmetrically with respect to the central axis CL of the tool body 10 on the outer peripheral surface of the distal end portion of the head portion 10 </ b> A. A flat mounting surface 21 for seating the tip 30 is formed on the wall surface of the mounting groove 20 on the rear side in the tool rotation direction K, and the bottom surface adjacent to the mounting surface 21 and the end surface on the tool base end side are formed. Are formed with flat constraining surfaces 22 and 23, respectively.

As shown in FIGS. 4 and 5, the chip 30 made of a hard material such as cemented carbide, cermet, or ceramic has a substantially rectangular plate shape and intersects at an acute angle with one corner portion of the upper surface 30a interposed therebetween. On the long side portion and the short side portion, a curved outer peripheral cutting edge rake face 32A and a secondary cutting edge rake face 32B, which are notched by grinding using a grinding wheel or powder press molding, are formed, respectively. A flat seating surface 34 is formed on the lower surface 30b. An outer peripheral cutting edge flank 33A is formed on a side surface adjacent to the outer peripheral cutting edge rake face 32A, and an outer peripheral cutting edge 31A is formed on the crossing ridge line portion between the outer peripheral cutting edge rake face 32A and the outer peripheral cutting edge flank 33A. Is formed. A secondary side flank 33B is formed on the flat side surface adjacent to the secondary cutting edge rake face 32B, and a straight secondary side cutting is formed at the intersection ridge line between the secondary cutting edge rake face 32B and the secondary cutting edge relief face 33B. A blade 31B is formed.
In a state where the tip 30 is mounted on the tool body 10, the length of the outer peripheral cutting edge 31A in the direction of the central axis CL is set in a range of 1 to 2 times the diameter D of the outer peripheral cutting edge of the present throw-away end mill 1. Has been. The outer peripheral cutting edge flank 33A is formed by a curved surface that protrudes outward in the direction along the outer peripheral cutting edge 31A and has a predetermined radius of curvature, and the outer peripheral cutting edge 31A corresponding to the outer peripheral cutting edge flank 33A is also a plan view. And is formed in a curved shape having a predetermined radius of curvature. Further, a corner blade flank 33C where the outer peripheral blade flank 33A and the auxiliary cutting flank 33B intersect is formed in a convex curved surface having a smaller radius of curvature than the outer peripheral blade flank 33A. The corner blade 31C corresponding to the surface 33C is formed in a convex curve shape having a smaller radius of curvature than the outer peripheral cutting edge 31A. The outer peripheral cutting edge relief surface 33A, the auxiliary cutting edge relief surface 33B, and the corner blade relief surface 33C intersect with the seating surface 34 so as to form an obtuse angle, and a positive relief angle is given.

  As shown in FIGS. 3A to 3C, the tip 30 has the upper surface 30a oriented in the tool rotation direction K, the seating surface 34 seated on the mounting surface 21, and the outer peripheral cutting edge 31A and the auxiliary cutting edge 31B. The flat constrained surfaces 37 and 38 provided on the side surfaces extending from the pair of long sides and short sides, respectively, are inserted into the mounting grooves 20 so as to contact the corresponding constraining surfaces 22 and 23, respectively. At this time, the outer peripheral cutting edge 31A and the auxiliary cutting edge 31B slightly protrude from the outer peripheral surface 10b and the distal end surface 10a of the tool body 10, respectively.

  Of the upper surface 30a of the chip 30, on the long side facing the outer peripheral cutting edge 31A, two concave portions 35A and 35B that are slightly depressed from the surface of the upper surface 30a and have a substantially semicircular shape in plan view are long sides. A part of the constrained surface 37 on the side is notched, and is formed substantially in parallel with the outer peripheral cutting edge 31A and in parallel with a gap on both sides of the intermediate point of the tip 30 in the direction of the outer peripheral cutting edge 31A. Yes. The bottom surfaces 36A and 36B of the recesses 35A and 35B form a flat surface, and the perpendicular P of the bottom surfaces 36A and 36B approaches the two restrained surfaces 37 and 38 as the seating surface 34 is approached. It inclines with respect to 34 perpendicular | vertical, The inclination-angle is in the range of 5 degrees-20 degrees.

On the wall surface side of the mounting groove 20 on the tool rotation direction K side, a central axis CLs extending parallel to the perpendicular P of the bottom surfaces 36A and 36B of the recesses is provided at a position facing the recesses 35A and 35B of the chip 30. Female screw holes 13A and 13B are formed, respectively. When the screw members 40A and 40B screwed into the female screw holes 13A and 13B press the bottom surfaces 36A and 36B in the direction of the perpendicular P with the front end surfaces 41A and 41B, each chip 30 is mainly attached to the mounting surface 21 side. And at least two restrained surfaces are also restrained, and in this embodiment, three restrained surfaces are restrained and stably clamped in the mounting groove 20. The
Moreover, each screw member 40A, 40B presses the bottom surface 36A, 36B at two locations spaced on both sides of the midpoint of the tip 30 in the direction of the outer peripheral cutting edge 31A, so that an even and large clamping force is obtained. Therefore, even when the cutting in the direction of the outer peripheral cutting edge 31A is small and local cutting resistance acts near the tip end side of the outer peripheral cutting edge 31A, the chip 30 does not move in the mounting groove 20, and the chip The positioning accuracy of 30 is very good.
When the angle formed between the perpendicular P of the bottom surfaces 36A and 36B of the recesses and the central axis CLs of the female screw holes 13A and 13B and the perpendicular of the seating surface 34 is less than 5 °, the force for pressing the chip 30 against the restraining surfaces 22 and 23 is exerted. When the angle exceeds 20 °, the chip 30 is strongly pressed against the restraining surfaces 22 and 23, the chip 30 is lifted from the mounting surface 21, and the chip 30 is moved during the cutting process to deteriorate the machining accuracy. Therefore, it is desirable to be within a range of 5 ° to 20 °.
The screw members 40A, 40B can be appropriately selected from known screw members such as hexagon socket set screws, hexagon socket bolts, countersunk screws, etc., and for the shape of the hole that engages with the screwdriver tool, Needless to say, the hole is not limited to a hexagonal hole or a cross-shaped hole, and can be appropriately changed to a known shape hole. The screw members 40A and 40B are made of general alloy steel or the like, but the tip portions including the tip surfaces 41A and 41B that press the tip 30 made of a hard material are wear resistant. In consideration of improvement of the above, it is desirable to braze and weld or build up a material having a hardness higher than that of the alloy steel.

Thus, in this embodiment, since the screw members 40A and 40B press the bottom surfaces 36A and 36B of the recesses slightly recessed from the top surface 30a of the chip 30, the chip 30 is clamped. Like the conventional tool 1 ′ shown in FIG. 5B, the tip 30 has a rigidity higher than that provided with a hole 35 ′ for receiving the screw member 40 ′ that penetrates the center of the tip 30 ′ in the upper and lower surfaces. Since the height is increased, the size and thickness of the upper and lower surfaces of the chip 30 can be reduced.
By reducing the size of the tip 30, the head portion 10 </ b> A of the tool body has sufficient thickness around the core thickness portion and the mounting groove 20 sandwiched between the two tips 30, and the rigidity of the tool body 10 is increased. Therefore, since the bending of the tool body 10 due to the cutting resistance is greatly suppressed as compared with the conventional tool 1 ′, it is possible to perform processing with high cutting conditions such as feeding and cutting, and improve processing accuracy.
Furthermore, in the present embodiment, since there is not formed anything that reduces the thickness of the female screw hole or the like on the mounting surface 21 side (part on the rear side in the tool rotation direction K) of the mounting groove 20, the rigidity of the mounting surface 21 is particularly high. Get higher. Therefore, the tip 30 is more firmly supported than the conventional tool 1 ′, and the problem of deformation and breakage of the mounting surface 21 is solved.

  In addition, since the tip 30 has a simple substantially rectangular plate shape, and the shape of the cutting edge and the bottom surfaces 36A and 36B of the recesses are not complicated, the conventional tool having a cutting head having a complicated shape as shown in FIG. In contrast, the chip 30 can be manufactured easily and at a low cost. As a secondary effect, the chip 30 can be attached and detached by loosening the screw members 40A and 40B by a predetermined amount without completely removing the screw members 40A and 40B from the tool body 10, so that the replacement of the chip 30 is quick and easy, and the work efficiency is improved. improves. Moreover, the problem of losing the screw members 40A and 40B during the replacement work is solved.

A main chip pocket 11 </ b> A and a sub chip pocket 11 </ b> B that are notched in a curved surface shape that is recessed toward the inside of the tool main body 10 are formed on the tool rotation direction K side of each mounting groove 20. Since the main chip pocket 11 </ b> A extends long in the direction of the central axis CL of the tool body 10, it is desirable to reduce the depth of depression toward the inside of the tool body 10.
Specifically, as shown in FIG. 3A, the sub-chip pocket 11 </ b> B is directed from the vicinity of the central axis CL of the distal end surface 10 a of the tool body 10 toward the tool base end side and radially outward in plan view. The main chip pocket 11A has a tool base end that is substantially parallel to the central axis CL following the sub chip pocket 11B and slightly behind the rear end portion of the mounting groove 20. It extends to the position on the part side. As shown in FIG. 6A, the curved wall surface of the main chip pocket 11A has the mounting surface 21 at the intersection of the bottom surface of the mounting groove 20 and the mounting surface 21 when viewed in a cross section perpendicular to the central axis CL. Is formed on the outer periphery side of the tool from the straight line perpendicular to the mounting surface 21 at a position approximately 50% of the depth from the outer peripheral surface 10b of the tool body 10 to the bottom surface.
Since the depth in the radial direction of the rear tip pocket 11B is set small in this way, the wall thickness on the wall surface side of the mounting groove 20 located on the rotation direction K side is sufficiently secured. In addition to the high rigidity of the head 10A, the effective diameter and pitch of the screw members 40A and 40B can be increased, and the durability and axial force of the screw members 40A and 40B can be improved.
Further, as can be seen from FIG. 1 and FIG. 6A, the boundary between the outer peripheral cutting edge rake face 32A and the main chip pocket 11A of the chip 30, and the auxiliary cutting edge rake face 32B and the auxiliary chip pocket 11B. Since the boundary portion is formed in a curved surface shape that smoothly connects so as not to cause a step, it is possible to discharge chips smoothly even though the chip pockets 11A and 11B have a small volume.

  As shown in FIGS. 3B and 3C, the tip 30 has an outer peripheral cutting edge 31A and an auxiliary cutting edge 31B slightly projecting from the outer peripheral surface 10a and the tip end surface 10b of the tool main body 10, respectively. A predetermined twist angle α and an outer peripheral rake angle β are given to the outer peripheral cutting edge 31A along the mounting groove 20 obliquely intersecting with the central axis CL of the ten at an angle α. In consideration of increasing the sharpness and reducing the cutting resistance, the outer peripheral cutting edge 31A is set to have a twist angle α in a range of 10 ° to 20 ° and an outer peripheral rake angle β in a range of −5 ° to 15 °. The This is because if the twist angle α is less than 10 °, the effect of reducing the cutting resistance is insufficient, and if it exceeds 20 °, it is difficult to ensure the thickness at the rear end of the mounting groove 20. This is because if the outer peripheral rake angle β is less than −5 °, the effect of reducing the cutting resistance cannot be obtained, and if it exceeds 15 °, the thickness on the mounting surface 21 side of the mounting groove 20 cannot be secured.

If at least the outer peripheral cutting edge rake face 32A is a twisted surface and the outer peripheral cutting edge 31A is formed into a twisted blade, the sharpness at each position of the outer peripheral cutting edge 31A becomes good and uniform, and the cutting in the direction of the outer peripheral cutting edge 31A increases. At this time, the cutting resistance acting on the tool body 10 and the chip 30 is reduced.
In addition, since the radius of rotation of the outer peripheral cutting edge 31A about the central axis CL is substantially constant, the perpendicularity and straightness of the wall surface of the work material are improved. Even when the outer peripheral cutting edge 31A is not a twisted blade, when the chip 30 is viewed in plan, the rotational radius of the outer peripheral cutting edge 31A about the central axis CL can be substantially reduced by forming a convex curve having a predetermined radius of curvature. Since it can be made constant, the perpendicularity and straightness of the wall surface of the work material can be made highly accurate.

  The length L of the outer peripheral cutting edge 31A in the central axis CL direction of the tool body is set within a range of 1 to 2 times the diameter D of the outer peripheral cutting edge of the throw-away end mill 1. If it does so, the effect which improves the rigidity of the tool main body 10 can fully be exhibited by enlarging the cutting | disconnection of the said center axis line CL direction, and performing highly efficient cutting. When the length L is twice or more the diameter D of the outer peripheral cutting edge, the thickness of the mounting groove 20 obliquely intersecting with the central axis CL is significantly reduced. The desired effect of increasing the rigidity of 10 may not be obtained.

  As described above, the throw-away end mill 1 has a configuration suitable for reducing the size of the tip 30, and is extremely effective in improving the rigidity of the tool body 10 in a small-diameter tool. When applied to a throw-away end mill in which the diameter D of the cutting edge is set in the range of 6 mm to 20 mm, a particularly beneficial effect is obtained.

  The throw-away rotary tool of the present invention is not limited to the embodiment described above, and can be changed as appropriate without departing from the gist of the present invention. For example, the tip 30 can be appropriately changed as long as it has a polygonal plate shape or a circular plate shape, and the rake face has a positive rake angle along a rake face or cutting edge formed of a flat surface parallel to the seating face 34. It can be changed to the inclined rake face provided, the clearance angle of the flank can be changed to negative (0 °), and two or more outer peripheral cutting edges 31A are provided over the entire peripheral edge of the upper surface of the tip 30 Is possible. The number of screw members may be one or two or more, and can be appropriately changed according to the size of the chip 30 and the desired clamp strength. Moreover, it cannot be overemphasized that it is applicable not only to an end mill but to drilling tools, such as a drill, a boring cutter, or a reamer, or milling tools, such as a face mill or a side cutter.

1 is a perspective view of a throw-away end mill to which the present invention is applied. FIG. 2 is a partially exploded perspective view of the throw-away end mill shown in FIG. 1. (A)-(c) is a top view of a throwaway type end mill shown in Drawing 1, a front view, and a tip view side view in order. It is a perspective view of the chip | tip with which the throwaway type end mill shown in FIG. 1 is mounted | worn. (A)-(e) is the rear view of the chip | tip shown in FIG. 4, a top view, a front view, a left view, and a right view in order. It is a figure which shows the cross-sectional shape cut | disconnected by the plane orthogonal to the central axis of a throw-away type end mill in the center part of a screw member, (a) is a cross-sectional shape of the throw-away type end mill to which this invention is applied, (b) is conventional. It is a cross-sectional shape of a tool. It is a perspective view of the cutting insert with which the conventional milling cutter is mounted. It is a front view of the milling cutter which mounts | wears with the cutting insert shown in FIG. It is a partial cross section front view of another conventional milling tool.

Explanation of symbols

1 Throw-away end mill (throw-away rotary tool)
10 Tool body 10a Tool body tip surface 10b Tool body outer peripheral surface 13A, 13B Female screw hole 20 Mounting groove 21 Mounting surface 22, 23 Constraining surface 30 Tip 30a Upper surface 30b Lower surface 31A Outer cutting edge 31B Sub cutting edge 32A Outer cutting edge scoop Surface 32B Secondary cutting edge rake surface 33A Peripheral cutting edge clearance surface 33B Secondary cutting edge clearance surface 34 Seating surface 35A, 35B Recess 36A, 36B Recess bottom surface 37, 38 Constrained surface 40A, 40B Screw member CL Center axis CLs of tool body Center axis P of female thread hole Perpendicular line D of bottom surface of recess D Diameter of outer peripheral cutting edge L Length of outer peripheral cutting edge α Torsion angle β External rake angle

Claims (6)

A tool body (10) rotated about a central axis (CL);
A tip (30) removably attached to at least one attachment groove (20) formed in the outer peripheral surface of the tip of the tool body (10) by a screw member (40A, 40B);
A throw-away rotary tool with
The chip (30) has a substantially plate shape,
Rake surfaces (32A, 32B) formed on the upper surface (30a) facing the tool rotation direction (K);
A seating surface (34) formed on the lower surface (30b) facing the upper surface (30a);
Flank faces (33A, 33B) formed on the side faces adjacent to the rake face (32A, 32B) and facing the outer periphery of the tool;
Cutting edges (31A, 31B) that are formed at the intersection ridge line portion of the rake face (32A, 32B) and the flank face (33A, 33B) and protrude from at least the outer peripheral surface (10b) of the tool body,
A constrained surface (37, 38) formed on at least one of a side surface facing the tool inner peripheral side or a side surface facing the tool proximal end side;
With
At least one female screw hole (13A, 13B) into which the screw member (40A, 40B) is screwed is provided on the wall surface side of the mounting groove (20) facing the upper surface (30a) of the chip,
At least one recess (35A, 35B) having a bottom surface pressed against the screw member (40A, 40B) is formed on the upper surface (30a) of the chip,
The constrained surface (37) as the central axis (CLs) of the female screw hole and the perpendicular (P) of the bottom surface of the recess approach the seating surface (34) with respect to the perpendicular of the seating surface (34). , 38), which is inclined so as to gradually approach the throwaway rotary tool. The angle between the central axis (CLs) of the female screw hole and the perpendicular (P) of the bottom surface of the recess and the perpendicular of the seating surface (34) is in the range of 5 ° to 20 °. Item 10. A throwaway rotary tool according to item 1. The cutting blades (31A, 31B) include an outer peripheral cutting blade (31A) and a sub cutting blade (31B) formed so as to protrude from the tip surface (10a) and the outer peripheral surface (10b) of the tool body,
The length (L) of the outer peripheral cutting edge in the central axis (CL) direction of the tool body is in the range of 1 to 2 times the diameter (D) of the outer peripheral cutting edge. The throw-away rotary tool according to 1 or 2. The throw-away rotary tool according to any one of claims 1 to 3, wherein the outer peripheral cutting edge (31A) is a helix blade having a helix angle (α). The twist angle (α) of the outer peripheral cutting edge is in the range of 10 ° to 20 °, and the outer peripheral rake angle (β) is in the range of -5 ° to 15 °. A throwaway rotary tool. The throwaway rotary tool according to any one of claims 1 to 5, wherein a diameter (D) of the outer peripheral cutting edge is in a range of 6 mm to 20 mm.

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