JP4940864B2 - Throw-away rotary tool and tip mounted on it - Google Patents

Description

  The present invention relates to a throw-away rotary tool such as a milling cutter and an end mill and a tip attached to the throw-away rotary tool. The present invention relates to a throw-away rotary tool and a tip attached to the throw-away rotary tool.

  The well-known technique regarding this type of throw-away rotary tool is illustrated in FIGS. The cutting insert shown in FIG. 10 has a parallelepiped basic shape, and is attached to a milling body to be rotated by a milling machine. The milling body shown in FIG. 11 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. 13 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, 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

Since the main cutting edge of the milling tool shown in FIG. 11 increases the working positive shaft angle, the rotation trajectory around the central axis of the milling tool does not become a straight line, which has a problem of deteriorating the straightness of the machining wall surface. . Further, the clearance angle of the flank at both ends of the main cutting edge in the direction of the main cutting edge is changed. In particular, in a small-diameter milling tool of about 20 mm or less, the change in the clearance angle becomes remarkably large, and when an appropriate clearance angle is set at a location where the clearance angle is the smallest, a significantly excessive clearance angle is generated at the location where the clearance angle is the largest. As a result, the main cutting edge is insufficient in strength, causing chipping and chipping. If the working positive shaft angle of the main cutting edge is not increased in order to increase the accuracy of the processing wall surface, there is a problem that the rake angle is reduced, the cutting resistance is increased, and the sharpness is deteriorated.
Furthermore, it is a thing of the form attached to a milling body with the screw | thread received by the hole 21 arrange | positioned in the center of a cutting insert, and as shown typically in FIG. 12, the center axis line of the said milling body passes through the center vicinity of a screw | thread. When the diameter of the outer peripheral cutting edge is reduced, the cross-sectional shape when cutting at a plane perpendicular to the surface of the milling body is close to the wall thickness (core thickness) of the milling body because the two cutting inserts approach, The rigidity of the milling body cannot be secured. 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 damage due to resistance (mainly the main component force), the accuracy of the machined wall deteriorates and it cannot be used unless the cutting conditions are significantly reduced compared to a solid end mill with the same tool diameter. There was a problem.

  In the milling tool shown in FIG. 13, the above-mentioned problem relating to the tool rigidity is not serious, but 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 a solid end mill or a solid drill. Since the shape of the head is also complicated, there is a problem that it is difficult to manufacture the cutting head and the cost required for the manufacturing becomes very high.

  The present invention has been made in order to solve the above-described problem, and improves the straightness in the rotation trajectory of the outer peripheral cutting edge without reducing the sharpness of the outer peripheral cutting edge, and also increases the rigidity of the tool body and the tip, thereby bending the tool. An object of the present invention is to provide a throw-away rotary tool that prevents deterioration of the accuracy of the machining wall surface and a tip attached to the throw-away rotary tool.

In order to solve the above problems, the present invention employs the following means. According to the first aspect of the present invention, at least one tip mounting seat is formed on the outer peripheral surface of the tip of the tool body in the tool body rotated about the central axis, and the tip placed on the tip mounting seat is formed. Is a throw-away rotary tool that is detachably mounted by at least one fixing means, and the tip having a substantially polygonal plate shape includes a rake surface formed on an upper surface facing a tool rotation direction, and the upper surface A seating surface formed on the lower surface facing the rake surface, a flank surface formed on a side surface that intersects the rake surface and faces the outer peripheral side of the tool, and an outer peripheral surface of the tool body that is formed at a cross ridge line portion of the rake surface and the flank surface. An outer peripheral cutting edge protruding from the outer peripheral cutting edge, and a constrained surface formed on at least one of the side face facing the inner peripheral side of the tool or the side face facing the tool base end side, and at least the outer peripheral cutting edge rake face connected to the outer peripheral cutting edge Table of The shape is substantially formed by press firing, and the surface shape of the outer peripheral cutting edge flank intersecting the outer peripheral cutting edge rake face is formed by grinding after press firing, and the axial rake is formed over the entire length of the outer peripheral cutting edge. The outer peripheral cutting edge rake face is formed of an inclined surface that increases the outer peripheral rake angle, the outer peripheral cutting edge flank is formed in a twisted surface, and from the central axis at each position of the outer peripheral cutting edge. A throw-away rotary tool characterized in that a distance to the outer peripheral cutting edge is substantially constant.
According to the first aspect of the present invention, the axial rake is positive over the entire length of the outer peripheral cutting edge, the outer peripheral cutting edge rake face is constituted by an inclined surface that increases the outer peripheral rake angle, and the outer peripheral cutting edge flank face is further provided. By forming a twisted surface, the cutting resistance of the outer peripheral cutting edge is small and the sharpness is good, and the distance from the central axis of the tool body to the outer peripheral cutting edge is substantially constant. The straightness of the rotation locus around the central axis is not deteriorated, and the accuracy of the machining wall surface is prevented from being deteriorated.
In addition, since the surface shape of the outer peripheral cutting edge rake face is substantially formed by press firing, the surface shape of the outer peripheral cutting edge rake face can be made to have a high degree of freedom. For example, an optimum outer peripheral rake angle that achieves both sharpness and cutting edge strength at each position in the outer peripheral cutting edge direction is set. In addition, since the surface shape of the outer peripheral cutting edge flank that intersects with the outer peripheral cutting edge rake face was formed by polishing after press firing, the intersecting ridge line portion between the outer peripheral cutting edge rake face and the outer peripheral cutting edge flank face The shape of the outer peripheral cutting edge formed in the above is formed with high accuracy, and the deterioration of the straightness of the rotation trajectory of the outer peripheral cutting edge is prevented.

According to a second aspect of the present invention, in the first aspect of the invention, the outer rake angle and the outer peripheral cutting edge over the entire length of the outer peripheral cutting edge in the central axis direction in a state where the insert is mounted on the tool body. The clearance angle of the flank is substantially constant.
According to the second aspect of the present invention, the outer peripheral rake angle and the clearance angle of the outer peripheral cutting edge flank are substantially constant over the entire outer peripheral cutting edge length of the tip mounted on the tool body. The cutting resistance and the cutting edge strength are made uniform, and the sharpness is stabilized and the cutting edge is extended.

The invention according to claim 3 is characterized in that, in the invention according to claim 1 or 2, the axial rake and the outer peripheral rake angle are positive.
According to the invention which concerns on Claim 3, since an axial rake and an outer periphery rake angle are made positive, cutting resistance is restrained small and the sharpness of an outer periphery cutting edge becomes favorable. Therefore, since the load applied to the tool body is small and bending is difficult to occur, the accuracy of the machining wall surface is prevented from being deteriorated. Furthermore, since occurrence of tool chatter is suppressed, cutting can be performed under higher cutting conditions than those of conventional tools.

The invention according to a fourth aspect is the invention according to any one of the first to third aspects, wherein the tip is formed in a long and substantially rectangular plate shape along the long side of the upper surface facing the tool rotation direction. The formed rake face, the seating face formed on the lower surface opposite to the upper face, the flank face formed on the side face adjacent to the rake face and facing the outer peripheral side of the rake face, and the ridge line between the rake face and the flank face And a constrained surface formed on at least one of a side surface connected to the long side located on the inner peripheral side of the tool and a side surface connected to the short side located on the tool base end side. The chip inserted into the mounting groove has at least two pressed parts spaced apart from each other in the central axis direction in a region adjacent to the rake surface on the top surface of the mounting groove facing the top surface of the chip. Provided at a position facing the pressed part on the wall surface side By a screw member screwed into the threaded hole, characterized in that it is fixed by being pressed against the seating surface side of the chip.
According to the invention of claim 4, since the screw member for fixing the chip to the tool body does not penetrate the upper and lower surfaces of the chip, the chip can be miniaturized, and the core thickness portion of the tool body to which the chip is mounted and A sufficient thickness is secured around the chip mounting seat. Further, since the female screw hole is not required on the bottom surface side of the chip mounting seat on which the chip is seated, the rigidity of the region on the bottom surface side becomes extremely high. From the above, since the bending of the tool main body due to the cutting resistance is suppressed, the accuracy of the machining wall surface is prevented from being deteriorated, and machining with higher cutting conditions than that of the conventional tool is possible.

The invention according to claim 5 is the tip attached to the throw-away rotary tool according to any one of claims 1 to 4, wherein the throw-away rotary tool according to any one of claims 1 to 4 is used. The chip to be mounted has a long, substantially rectangular plate shape, and an outer peripheral cutting edge is formed on a long side adjacent to at least one corner on the upper surface, and an outer peripheral cutting blade is formed on the upper surface connected to the outer peripheral cutting blade. A rake face is formed, a peripheral cutting edge flank face is formed on a side surface intersecting the peripheral cutting edge rake face, a surface shape of the peripheral cutting edge rake face is substantially formed by press firing, and the peripheral cutting edge is formed. The surface shape of the flank face is formed by grinding after press firing, and the rake angle of the rim face of the outer peripheral cutting edge is directed from one end of the outer peripheral cutting edge to the other end in a cross section perpendicular to the outer peripheral cutting edge. Therefore, while gradually decreasing The clearance angle of the outer peripheral cutting edge flank is gradually increased, and the blade angle formed by the outer peripheral cutting edge rake face and the outer peripheral cutting edge flank is substantially constant over the entire length of the outer peripheral cutting edge. It is a chip to do.
According to the invention of claim 5, since the surface shape of the outer peripheral cutting edge rake face is substantially formed by press firing, the surface shape of the outer peripheral cutting edge rake face can be made to have a high degree of freedom. Since the surface shape of the peripheral cutting edge flank adjacent to the peripheral cutting edge rake face was formed by polishing after press firing, the cross ridge line between the peripheral cutting edge rake face and the peripheral cutting edge flank face The shape of the outer peripheral cutting edge formed in the portion can be formed with high accuracy. When such a tip is mounted on the tool body of a throw-away rotary tool, it is possible to set an optimum outer peripheral rake angle that achieves both sharpness and cutting edge strength at each position in the outer peripheral cutting edge direction. The straightness of the rotation trajectory of the outer peripheral cutting edge is prevented from deteriorating.

According to the throw-away rotary tool and the tip mounted thereon according to the present invention, the axial rake is positive over the entire length of the outer peripheral cutting edge, and the outer peripheral cutting edge rake face is an inclined surface that increases the outer peripheral rake angle. In addition, since the outer peripheral cutting edge flank surface is formed in a twisted surface, the cutting resistance of the outer peripheral cutting edge is small and the sharpness is good, and the outer peripheral cutting edge is cut from the central axis of the tool body at each position of the outer peripheral cutting edge. Since the distance to the blade is substantially constant, the straightness of the rotation trajectory of the outer peripheral cutting blade around the central axis is not deteriorated, and the accuracy of the machining wall surface is prevented from being deteriorated.
In addition, since the surface shape of the outer peripheral cutting edge rake face is substantially formed by press firing, the surface shape of the outer peripheral cutting edge rake face can be made to have a high degree of freedom. For example, an optimum outer peripheral rake angle that achieves both sharpness and cutting edge strength at each position in the outer peripheral cutting edge direction is set. In addition, since the surface shape of the outer peripheral cutting edge flank that intersects with the outer peripheral cutting edge rake face was formed by polishing after press firing, the intersecting ridge line portion between the outer peripheral cutting edge rake face and the outer peripheral cutting edge flank face Since the distance from the central axis of the tool main body to the outer peripheral cutting edge at each position of the outer peripheral cutting edge formed with higher accuracy is formed with high accuracy, deterioration of straightness in the rotation trajectory of the outer peripheral cutting edge is prevented.

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. (A)-(c) of Drawing 3 is a top view, a front view, and a tip view side view of an end mill shown in Drawing 1, respectively. FIG. 4 is an enlarged plan view of the tip of the end mill shown in FIG. 5 to 7 are a sectional view taken along line S1-S1, a sectional view taken along line S2-S2, and a sectional view taken along line S3-S3 in FIG. FIG. 8 is a perspective view of a tip mounted on the end mill shown in FIG. 9A to 9D are a rear view, a plan view, a front view, and a right side view of the chip shown in FIG. 8, respectively.

  As shown in FIGS. 1 to 3, the throw-away end mill 1 according to the present embodiment includes a long cutting edge in two mounting grooves 20 provided on the outer peripheral surface of the tip of a tool body 10 having a substantially round bar shape. A chip 30 having a substantially polygonal plate shape is inserted so that its longitudinal direction is substantially parallel to the direction of the central axis CL of the tool body, and two screw members 40A and 40B serving as fixing means are used. And is detachably fixed.

  The tool body 10 has a substantially round bar shape, and includes a head portion 10A formed on the tool distal end side, and a shank portion 10B having a slightly larger diameter formed on the tool base end side continuous with the head portion 10A. ing. Further, on the outer peripheral surface of the distal end portion of the head portion 10A, two chip mounting seats 20 having a groove shape extending from the distal end surface 10a toward the tool proximal end side are substantially symmetrical with respect to the central axis CL of the tool main body 10. Is formed. A flat mounting surface 21 for seating the chip 30 is formed on the wall surface of the chip mounting seat 20 on the rear side in the tool rotation direction K. The bottom surface adjacent to the mounting surface 21 and the wall surface on the tool base end side. Are formed with constraining surfaces 22 and 23 each having a flat surface.

  A chip pocket for discharging chips is formed in the outer peripheral surface of the tool body 10 adjacent to the tool rotation direction K side of each chip mounting seat 20. This chip pocket is composed of a main chip pocket 11A and a sub chip pocket 11B. The main chip pocket 11A is an end on the tool base end side of the chip mounting seat 20 from the tip surface 10a of the tool body in the direction of the central axis CL of the tool body. It has a curved wall surface that extends to the vicinity of the portion and is recessed toward the inside of the tool body 10 in a cross section orthogonal to the central axis. The sub-chip pocket 11B is adjacent to the tool tip end side of the main chip pocket 11A, and is centered so as to go from the vicinity of the center axis CL of the tip surface 10a of the tool body toward the tool base end side and the tool outer peripheral side in plan view. It is formed to be inclined with respect to the axis line CL.

  As shown in FIGS. 8 and 9, the chip 30 made of a hard material such as cemented carbide, cermet, or ceramic has an elongated substantially polygonal plate shape, preferably a substantially rectangular plate shape, and has an upper surface 30a. An outer peripheral cutting edge 31A and an auxiliary cutting edge 31B are formed on the long side and the short side adjacent to each other with the corner 31C having a circular arc shape in plan view interposed therebetween. Further, an outer peripheral cutting edge rake face 32A continuous with the outer peripheral cutting edge 31A and a secondary cutting edge rake face 32B continuous with the auxiliary cutting edge 31B are formed on the upper surface 30a of the chip. The outer peripheral cutting edge rake face 32A and the auxiliary cutting edge An outer peripheral cutting edge relief surface 33A and a secondary cutting edge relief surface 33B are respectively formed on the side surfaces of the chip 30 adjacent to the rake face 32B. At least the surface shape of the outer peripheral cutting edge rake face 32A is formed by press firing, or after press firing, using free abrasive grains or the like to impart honing along the ridgeline of the outer peripheral cutting edge 31A. Although it is polished, the surface shape formed by press firing is substantially maintained, so that it is substantially formed by press firing. Further, over the entire length of the outer peripheral cutting edge 31A, the outer peripheral cutting edge rake face 32A is formed as an inclined surface that gradually approaches the seating surface 34 as the distance from the outer peripheral cutting edge 31A increases, and is given a positive rake angle. . Further, the rake angle of the outer peripheral cutting edge rake face 32A changes so as to gradually decrease from the sub cutting edge side end portion to the other end portion of the outer peripheral cutting edge 31A.

  An outer peripheral cutting edge relief surface 33A and an auxiliary cutting edge relief surface 33B are formed on each side surface of the tip connected to the outer peripheral cutting edge 31A and the auxiliary cutting edge 31B. The surface shape of at least the outer peripheral cutting edge clearance surface 33A is formed by grinding using a grinding wheel, and the clearance angle gradually increases from the corner 31C side end portion to the other end portion of the outer peripheral cutting blade 31A. It is formed by the formed twisted surface.

  In a region on the long side facing the outer peripheral cutting edge 31 </ b> A on the upper surface 30 a of the chip 30, a pressed portion 35 that is pressed by the screw members 40 </ b> A and 40 </ b> B that are fixing means when being attached to the tool body 10 is provided. ing. The pressed portion 35 is slightly depressed from the surface of the upper surface 30a toward the lower surface 30b in the thickness direction of the chip 30, and includes two concave portions 35A and 35B having a substantially semicircular shape in plan view. The concave portions 35A and 35B are cut out at a part of the side surface extending from the long side, and are provided on both sides with an intermediate point of the entire length in the longitudinal direction of the chip 30 therebetween. The bottom surfaces 36A and 36B of the recesses 35A and 35B are flat surfaces, and the normal P of the seating surface 34 gradually approaches the two constrained surfaces 37 and 38 as the normal P approaches the seating surface 34. It is inclined and formed so that its inclination angle is in the range of 5 ° to 20 ° (see FIG. 5).

  When the tip 30 is mounted on the tool body 10, as shown in FIGS. 3A to 3C, the upper surface 30a is directed in the tool rotation direction K, and its seating surface 34 is the mounting surface of the tip mounting seat. 21 is placed on the chip mounting seat 20 so that the restrained surfaces 37 and 38 abut against the restraining surfaces 22 and 23 of the corresponding chip mounting seats, respectively. At this time, the outer peripheral cutting edge 31A and the auxiliary cutting edge 31B of the chip protrude from the outer peripheral surface 10b and the tip end surface 10a of the tool body 10, respectively.

  On the wall surface side of the tip mounting seat 20 on the tool rotation direction K side, there is a central axis CLs extending in parallel with the perpendicular P of the bottom surfaces 36A and 36B of the recesses at a position facing the recesses 35A and 35B of the tip 30. The female screw holes 13A and 13B are formed. 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 is also pressed to the respective restraining surfaces 22 and 23 side and is firmly clamped in the chip mounting seat 20.

  As shown in FIG. 3, in the front view of the present throwaway end mill 1, the tip 30 is inclined so as to go to the tool rotation direction K rear side as it goes from the tool distal end side to the tool base end side of the tool body 10. Thus, the positive axial rake γp is set, and the tip 30 rises from the center axis CL of the end mill end mill 1 when viewed from the front end of the present throw-away end mill 1, and is set to a negative radial rake γf ′. ing. The radial rake γf ′ is the most negative at the forefront of the outer peripheral cutting edge 31A, but gradually increases toward the tool base end side. As described above, the outer peripheral cutting edge rake face 32A of the chip is given a positive rake angle over the entire length of the outer peripheral cutting edge 31A, and the rake angle gradually increases from the secondary cutting edge side end toward the other end. Therefore, the outer peripheral rake angle γf in the throw-away end mill 1 is increased by adding the rake angle of the outer peripheral cutting edge rake face 32A to the radial rake γf ′ determined by the tip mounting posture. It is set to a substantially constant value over the entire length of the cutting blade 31A.

  Further, as described above, the outer peripheral cutting edge clearance surface 33A of the chip is formed of a twisted surface whose clearance angle gradually increases from the leading edge of the outer peripheral cutting edge 31A toward the rear end side. The outer peripheral clearance angle αf in the end mill has a substantially constant value over the entire length of the outer peripheral cutting edge 31A.

  Further, the tip 30 mounted on the tool body 10 is formed by an inclined plane whose outer peripheral cutting edge 31A is inclined in a direction parallel to the axial rake γp direction on the cylindrical surface around the central axis CL of the throw-away end mill 1. It is formed to be substantially equal to the contour shape of the cutting surface, and is formed such that the distance from the central axis CL to the outer peripheral cutting edge 31A at each position of the outer peripheral cutting edge 31A is substantially constant. In the single chip 30, when the chip 30 is viewed in plan, the outer peripheral cutting edge 31 </ b> A is formed in a predetermined curved shape projecting outward from the both end portions toward the intermediate portion.

  According to the throw-away end mill 1 having the above-described configuration and the tip 30 attached thereto, the outer peripheral rake face 32A provided with a positive rake angle over the entire length of the outer peripheral cutting edge 31A is the outer peripheral rake angle γf of the end mill. Since the outer peripheral cutting edge relief surface 33A is formed in a twisted surface, the cutting resistance is small and the sharpness is improved. Further, since the distance from the central axis CL of the outer peripheral cutting edge 31A tool body 10 to the outer peripheral cutting edge 31A is substantially constant over the entire length of the outer peripheral cutting edge 31A, the outer peripheral cutting edge with the central axis CL as the rotation center. The straightness of the rotation trajectory of 31A does not deteriorate, and the accuracy of the machining wall surface is suppressed.

  Further, since the surface shape of the outer peripheral cutting edge rake face 32A is substantially formed by press firing, a shape with a high degree of freedom can be formed, and both sharpness and cutting edge strength can be achieved at each position in the direction of the outer peripheral cutting edge 31A. Therefore, it is possible to set the optimum outer peripheral rake angle γf. Moreover, since the surface shape of the outer peripheral cutting edge flank 33A intersecting with the outer peripheral cutting edge rake face 32A is formed by grinding after press firing, the outer peripheral cutting edge rake face 32A and the outer peripheral cutting edge flank 33A. Since the distance from the central axis CL of the tool body 10 to the outer peripheral cutting edge 31A at each position of the outer peripheral cutting edge 31A formed at the crossing ridge line with the outer peripheral cutting edge is substantially constant, the rotation locus Deterioration of straightness is suppressed.

  When the tip 30 is mounted on the tool body 10, the outer peripheral rake angle γf and the outer cutting edge flank clearance angle αf are substantially constant over the entire length of the outer peripheral cutting edge 31A in the central axis CL direction of the tool main body 10. Therefore, the cutting resistance and the cutting edge strength at each position of the outer peripheral cutting edge 31A are made uniform, and the sharpness is stabilized and the life of the outer peripheral cutting edge 31A is extended.

  Since the axial rake γp of the outer peripheral cutting edge is positive and the outer peripheral rake angle γf is increased by the outer peripheral cutting edge rake face of the chip, the cutting resistance is reduced and the sharpness is improved. Therefore, since the load applied to the tool body 10 is small and bending is difficult to occur, the accuracy of the machining wall surface is reduced. Furthermore, since the occurrence of tool chatter is suppressed, it is possible to perform machining under higher cutting conditions than those of conventional tools.

  In consideration of reducing the cutting resistance of the outer peripheral cutting edge 31A and increasing the sharpness, the axial rake γp is set in the range of 10 ° to 20 °, and the outer rake angle γf is set in the range of −5 ° to 15 °. It is desirable to be done. This is because if the axial rake γp is less than 10 °, the effect of reducing the cutting resistance is insufficient, and if it exceeds 20 °, the thickness of the mounting groove 20 on the mounting surface 20 side is secured at the rear end portion of the mounting groove 20. Because it becomes difficult. Further, even when the outer peripheral rake angle γf is less than −5 °, the effect of reducing the cutting resistance is insufficient. When the outer peripheral rake angle γf exceeds 15 °, the outer rake angle of the outer peripheral cutting edge 31A becomes excessive and the strength of the outer peripheral cutting edge 31A is insufficient. This is because the radial rake γf ′ may be excessive and the thickness of the mounting groove 20 on the mounting surface 21 side may not be sufficiently secured.

  Regarding the method of mounting the tip 30 on the tool body 10, in the present throw-away end mill 1, 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 tip to clamp the tip 30. Therefore, as in the conventional tool 1 'shown in FIG. 12, compared to a tool provided with a hole 35' for receiving a screw member 40 'penetrating the central portion of the tip 30' on the upper and lower surfaces. Since the rigidity of the chip 30 is increased, the size and thickness of the upper surface and the lower surface of the chip 30 can be reduced, and the chip 30 can be reduced in size. With the miniaturization of the tip 30, the tool body head 10A has a sufficient core thickness between the two tips 30 and a thickness around the tip mounting seat 20 to increase the rigidity of the tool body 10. Therefore, since the bending of the tool body 10 due to the cutting resistance is significantly suppressed as compared with the conventional tool 1 ′, the accuracy of the machining wall surface is prevented from being deteriorated, and machining with higher cutting conditions than that of the conventional tool is possible.

  Further, in the present throw-away end mill 1, the thickness and strength of a female screw hole or the like are reduced on the mounting surface 21 side of the tip mounting seat 20 that mainly receives the main component force acting in the tangential direction of the end mill 1. Since no tip is formed, the tip 30 can be supported more firmly than the conventional tool 1 ′, so that the tool body 10 can be prevented from bending and chattering, and the accuracy of the machining wall surface can be prevented from deteriorating.

  Further, the perpendicular P of the bottom surfaces 36A and 36B of the recesses of the chip and the central axis CLs of the screw members 40A and 40B are inclined so as to gradually approach the restrained surfaces 37 and 38 as they approach the seating surface 34, and the screw members 40A, Since 40B presses the bottom surfaces of the recesses 35A and 35B toward the seating surface 34, the tip 30 has the seating surface 34 and the restrained surfaces 37 and 38, the mounting surface 24 of the tip mounting seat and the restraint. It is pressed against each of the surfaces 22 and 23 and is firmly clamped in the chip mounting seat 20. In particular, since the seat seating surface 34 and the restrained surfaces 37 and 38 and the tip mounting seat mounting surface 24 and the restraining surfaces 22 and 23 intersect each other at approximately 90 °, the motion of the tip 30 due to cutting resistance is achieved. Is prevented and accuracy deterioration of the processed wall surface is prevented. In particular, by setting the angle formed by the perpendicular P of the bottom surfaces 36A and 36B of the recesses and the central axis CLs of the screw members 40A and 40B and the perpendicular of the seating surface 34 within a range of 5 ° to 20 °, the chip 30 The clamping force can be made stronger and the clamping accuracy can be made accurate. This is because if the angle is less than 5 °, the force for pressing the tip 30 against the restraining surfaces 22 and 23 is insufficient, and if the angle exceeds 20 °, the tip 30 is strongly pressed against the restraining surfaces 22 and 23. This is because the tip 30 may be lifted from the mounting surface 24, so that the tip 30 may move during the cutting process and cause deterioration in accuracy of the machining wall surface.

  Furthermore, since each screw member 40A, 40B presses the bottom surfaces 36A, 36B of the recesses provided at two positions with a gap on both sides across the intermediate point in the longitudinal direction of the chip 30, a large clamp The force acts evenly on the tip 30. Therefore, even when the cutting in the direction of the outer peripheral cutting edge 31A is small and a local cutting resistance acts near the distal end side of the outer peripheral cutting edge 31A, the chip 30 does not move in the chip mounting seat 20, and the chip 30 Since the positioning accuracy is extremely good, deterioration of the accuracy of the machining wall surface is prevented.

  The length L of the outer peripheral cutting edge 31A in the direction of the central axis CL of the tool body 10 is set within a range of 1 to 2 times the diameter D of the outer peripheral cutting edge 31A of the present throw-away end mill 1. Then, in the high-efficiency cutting that increases the depth of cut in the central axis CL direction, the effect of improving the rigidity of the tool body 10 is sufficiently exerted, and the above-described effect of reducing the accuracy of the machining wall surface described above is achieved. Become prominent. In addition, when the length L is set to be twice or more the diameter D of the outer peripheral cutting edge, the thickness of the tip mounting seat 20 obliquely intersecting the central axis CL greatly decreases in thickness. There is a possibility that an expected effect of increasing the rigidity of the main body 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, this is particularly effective in preventing deterioration in accuracy of the machining wall surface.

  The throw-away rotary tool of the present invention is not limited to the embodiment described above, and can be applied to a throw-away front milling cutter, a throw-away side cutter, and the like.

1 is a perspective view of a throw-away end mill according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the throw-away end mill shown in FIG. 1. (A)-(c) is the top view of a throwaway type end mill shown in Drawing 1, a front view, and a tip view side view, respectively. It is a front-end | tip part enlarged plan view of the throw away type end mill shown in FIG. It is the S1-S1 sectional view taken on the line in FIG. It is the S2-S2 sectional view taken on the line in FIG. It is the S3-S3 sectional view taken on the line in FIG. It is a perspective view of the chip | tip with which the throwaway type end mill shown in FIG. 1 is mounted | worn. (A)-(d) is the rear view of the chip | tip shown in FIG. 8, a top view, a front view, and a right view, respectively. 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 schematic diagram of the cross section orthogonal to the axis of the milling cutter 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)
DESCRIPTION OF SYMBOLS 10 Tool main body 10a Tool body front end surface 10b Tool main body outer peripheral surface 13A, 13B Female screw hole 20 Tip mounting seat 21 Mounting surface 22, 23 Constraining surface 30 Tip 30a Upper surface 30b Lower surface 31A Outer cutting blade 31B Sub cutting blade 32A Outer cutting blade Rake face 33A Outer peripheral cutting edge relief face 34 Seating face 35 Pressed part 35A, 35B Recess 36A, 36B Recess bottom face 37, 38 Restrained face 40A, 40B Screw member (fixing means)
CL Center axis D of tool body Diameter of outer peripheral cutting edge γp Axial rake γf 'Radial rake γf Outer rake angle

Claims (4)

At least one tip mounting groove is formed in the outer peripheral surface of the tip of the tool body on the tool body rotated around the central axis, and the chip placed in the chip mounting groove is attached and detached by at least one fixing means. It is a throw-away rotary tool that is freely mounted,
The chip having a substantially polygonal plate shape,
A rake face formed on the upper surface facing the tool rotation direction, a seating surface formed on the lower surface facing the upper face, a flank face formed on a side surface that intersects the rake face and faces the outer peripheral side of the tool, and a rake face And a constrained surface formed on at least one of the outer peripheral cutting edge formed at the intersection ridge line portion of the flank and protruding from the outer peripheral surface of the tool body, and the side surface facing the tool inner peripheral side or the side surface facing the tool base end side And
The upper surface of the chip is projected upward from the upper surface along at least two pressed portions provided apart from each other in the central axis direction and the opening end of the wall surface of the mounting groove facing the upper surface. And a step portion to be provided,
At least the surface shape of the outer peripheral cutting edge rake face connected to the outer peripheral cutting edge is substantially formed by press firing, and the surface shape of the outer peripheral cutting edge flank intersecting the outer peripheral cutting edge rake face is obtained by grinding after press firing. Forming,
Axial rake is positive over the entire length of the outer peripheral cutting edge,
In the cross section orthogonal to the outer peripheral cutting edge, the rake angle of the rake face of the outer peripheral cutting edge of the tip is gradually decreased from the tool distal end side toward the tool base end side, while the outer periphery of the tip The clearance angle of the flank of the cutting edge is gradually increased from the tool tip side toward the tool base end side, and the tip scoop defined with respect to the tool body over the entire length of the outer peripheral cutting edge The angle γf and the clearance angle αf are constant, and
Indexable rotating tool, characterized in that the distance a constant to the outer peripheral cutting edge from said central axis at each position of the peripheral cutting edge. Indexable rotary tool according to claim 1 Symbol mounting, characterized in that the rake angle γf of the chips specified were positive with respect to the tool body. The chip is
A rake surface formed along the long side of the upper surface facing the tool rotation direction, a seating surface formed on the lower surface facing the upper surface, and adjacent to the rake surface. The flank formed on the side facing the tool outer peripheral side, the outer peripheral cutting edge formed at the crossing ridge line portion of the rake surface and the flank, the side surface connected to the long side located on the inner peripheral side of the tool, and the tool base end A constrained surface formed on at least one of the side surfaces connected to the short side located on the side,
An internal thread in which the seating surface and the restrained surface are in contact with the corresponding wall surface of the mounting groove, and the pressed portion provided on the upper surface of the chip is provided on the wall surface side of the mounting groove facing the upper surface. 3. The throw-away rotary tool according to claim 1, wherein the throw-away rotary tool is fixed to the mounting groove by being pressed toward the seating surface side of the tip by the screw member screwed into the hole. The tip mounted on the throw-away rotary tool according to any one of claims 1 to 3 , wherein the tip is formed in a long and substantially rectangular plate shape, and a long side adjacent to at least one corner on the upper surface thereof has an outer periphery. A cutting edge is formed, an outer peripheral cutting edge rake face is formed on the upper surface connected to the outer peripheral cutting edge, an outer peripheral cutting edge relief face is formed on a side surface intersecting the outer peripheral cutting edge rake face, and the outer peripheral cutting edge rake is formed. The surface shape of the surface is substantially formed by press firing, and the surface shape of the outer peripheral cutting edge flank is formed by grinding after press firing, and the outer peripheral cutting edge rake is cut in a cross section perpendicular to the outer peripheral cutting edge. While the rake angle of the surface gradually decreases from one end to the other end of the outer peripheral cutting edge, the clearance angle of the outer peripheral cutting edge flank gradually increases, and the outer peripheral cutting edge rake face and the outer peripheral cutting edge clearance are increased. The blade angle made with the surface is Chip, characterized in that there is a a certain over the entire length of the peripheral cutting edge.

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