JP2008080470A - Throw-away type rotating tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a throw-away type rotating tool capable of heightening rigidity of a tool body and a tip, and tightly fixing the tip to a tool body with a strong clamping force. <P>SOLUTION: In this throw-away type rotating tool 1, the tip 30 is detachably mounted in a mounting groove 20 provided on an outer periphery at a tip of a tool body 10 by at least two screw members 40A, 40B. The tip is fixed to the mounting groove 20 by pressing at least two pressurized parts 35 spaced from each other in a center axial line CL direction of the tool body on a top face 20a toward a seating face 34 of the tip by the screw members 40A, 40B screwed on the wall of the mounting groove 20 faced to the top face 30a of the tip. Portions of the pressurized part 35 to be pressurized by the screw members 40A, 40B are arranged on the outer peripheral side of the tool for the pressurized part 35, which is located nearer the tool base end in the center axial line CL direction. <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 more particularly to a technique for improving the tool rigidity and the tip clamping strength of a throw-away rotary tool having a small outer peripheral diameter. It is.

  Known techniques relating to this type of throw-away rotary tool are illustrated in FIGS. The cutting insert shown in FIG. 11 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. 12 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. 14 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. 11 and 12 is configured to be attached to the milling body by a screw received in a hole 21 arranged in the center of the cutting insert. As schematically shown in FIG. When the tool diameter (diameter of the outer peripheral cutting edge) is reduced, the cross-sectional shape when cutting in a plane that passes through the vicinity and orthogonal to the central axis of the milling body is close to the center of the milling body because the two cutting inserts approach each other. The thickness (core thickness) of the portion 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. As the cutting insert is downsized, the screws are also downsized, and there is a risk that the clamping strength of the cutting insert will be insufficient.
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 plastic deformation and breakage due to resistance (mainly the main component force) may occur, there is a problem that it cannot be used unless the cutting conditions are considerably reduced compared to a solid end mill having the same tool diameter.

In the milling tool shown in FIG. 14, the problem of the tool rigidity described above is not large, but the shape of the cutting heads 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 solid drill, and the holding means Since the shape is also complicated, there is a problem that it is difficult to manufacture the cutting head 10 and the cost required for the manufacturing becomes very high.
Moreover, since the hollow part for accommodating the asymmetric means 15 and 19 is provided in the front-end | tip part of the shank 12, it is difficult to ensure the intensity | strength of this shank 12, and the clamp intensity | strength of the cutting head 10 becomes inadequate, and it cuts. In addition, there is a risk of unstable behavior in high-feed cutting.

  The present invention has been made in order to solve the above-mentioned problems. The rigidity of the tool body and the tip is increased, and the tip is firmly fixed to the tool body by a strong clamping force, which is higher than that of this type of conventional tool. An object of the present invention is to provide a throw-away rotary tool capable of performing stable machining under conditions.

  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 mounting groove is formed in the outer peripheral surface of the tip of the tool body in the tool body rotated around the central axis, and the chip inserted into the mounting groove is provided at least. A throw-away rotary tool that is detachably mounted by two screw members, the tip having a long and substantially plate shape is a rake formed along the long side of the upper surface facing the tool rotation direction A flank, a seating surface formed on the lower surface opposite to the upper surface, a flank surface formed on a side surface that intersects the rake surface and faces the outer peripheral side of the tool, and a ridge line portion between the rake surface and the flank surface. And an outer peripheral cutting edge projecting from the outer peripheral surface of the tool body, and a restrained surface formed on at least one of the side surface facing the tool inner peripheral side and the side surface facing the tool proximal end side, and the seating surface and the covered surface Before constraining the surface A female screw hole provided on the wall surface side of the mounting groove facing the upper surface, and at least two pressed parts provided on the upper surface of the chip and spaced apart from each other in the direction of the central axis, respectively, abutting against the wall surface of the mounting groove By pressing toward the seating surface side of the tip by the screw member that is screwed onto the tip, the pressing portion of the pressed portion by the screw member is fixed to the tool base end in the central axis direction. The throwaway rotary tool is characterized in that the pressed part on the part side is arranged on the outer peripheral side of the tool.

  According to the first aspect of the present invention, 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 chip is mounted. Thickness around the core thickness part of the tool body and the mounting groove is sufficiently secured. Furthermore, since the female screw hole is not 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.

  Further, since the screw member does not penetrate the tip, the tip can be miniaturized without requiring the screw member to be miniaturized, and further separated from each other in the direction of the central axis of the tool body. Since the two screw members press the pressed part provided on the upper surface of the tip toward the seating surface, the tip is firmly fixed to the tool body by a strong clamping force, so the load is large for cutting and feeding. In this cutting process, chattering is difficult to occur and stable cutting is possible, thereby preventing deterioration of machining accuracy.

  In addition, as the pressed portion on the tool base end side in the central axis direction is pressed at a position closer to the outer peripheral cutting edge of the tip because the pressed portion by the screw member is disposed on the outer peripheral side of the tool, Clamping strength is increased and clamping accuracy is improved. On the other hand, the pressed portion on the tool tip side is arranged on the tool inner peripheral side and the position far from the outer peripheral cutting edge is pressed on the tool inner peripheral side, so that the dynamic clamping strength of the chip is increased. This increases the vibration and displacement of the tip due to the cutting force acting on the outer peripheral cutting edge during the cutting process, so that stable machining can be performed under high cutting conditions. Moreover, since the outer shape of the chip and the shape of the cutting edge are not complicated, the chip can be manufactured easily and at low cost.

According to a second aspect of the present invention, in the invention according to the first aspect, the tool body is provided with a chip pocket extending along the mounting groove and adjacent to the tool rotation direction side of the mounting groove. The wall surface facing the tool outer peripheral side is formed so as to gradually move away from the central axis as it goes from the tool distal end side to the tool proximal end side.
According to the invention described in claim 2, the wall surface facing the tool outer peripheral side of the tip pocket extending adjacent to the tool rotation direction of the mounting groove is from the central axis line as it goes from the tool distal end side to the base end side. Since it is formed so as to gradually go away, the thickness around the screw member and the female screw hole arranged on the tool outer peripheral side so as to press the pressed part located on the tool base end side in the area close to the outer peripheral cutting edge Is ensured, and a reduction in the rigidity of the tool body can be prevented.

The invention according to claim 3 is characterized in that, in the invention according to claim 1 or 2, contact between the pressed portion and the screw member is point contact.
According to the invention of claim 3, since the pressed portion by the screw member is fixed, the operational effect of the invention of claim 1 is effective and stable.

The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the length of the outer peripheral cutting edge in the central axis direction is at least one and twice the diameter of the outer peripheral cutting edge. It is characterized by the following range.
When the length of the outer peripheral cutting edge in the central axis direction of the tool body is in the range of 1 to 2 times the diameter of the outer peripheral cutting edge as in the invention according to claim 4, The effect of the invention according to No. 3 becomes more effective, and high-efficiency cutting can be performed in which the cut in the central axis direction is increased.

Since the present invention employs a configuration in which 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 on which the chip is mounted And the thickness around the mounting groove is sufficiently secured. Furthermore, since the female screw hole is not 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.
Further, since the screw member does not penetrate the tip, the tip can be miniaturized without requiring the screw member to be miniaturized, and further separated from each other in the direction of the central axis of the tool body. Since the two screw members press the pressed part provided on the upper surface of the tip toward the seating surface, the tip is firmly fixed to the tool body by a strong clamping force, so the load is large for cutting and feeding. In this cutting process, chattering is difficult to occur and stable cutting is possible, thereby preventing deterioration of machining accuracy.
In addition, as the pressed portion on the tool base end side in the central axis direction is pressed at a position closer to the outer peripheral cutting edge of the tip because the pressed portion by the screw member is disposed on the outer peripheral side of the tool, Clamping strength is increased and clamping accuracy is improved. On the other hand, the pressed portion on the tool tip side is arranged on the tool inner peripheral side and the position far from the outer peripheral cutting edge is pressed on the tool inner peripheral side, so that the dynamic clamping strength of the chip is increased. This increases the vibration and displacement of the tip due to the cutting force acting on the outer peripheral cutting edge during the cutting process, so that stable machining can be performed under high cutting conditions. Moreover, since the outer shape of the chip and the shape of the cutting edge are not complicated, the chip can be manufactured easily and at low cost.

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 an enlarged plan view of the tool tip of the end mill shown in FIG. FIG. 5 is an enlarged front view of the tool tip of the end mill shown in FIG. 6 and 7 are a sectional view taken along line S1-S1 and a sectional view taken along line S2-S2 in FIG. FIG. 8 is a cross-sectional view equivalent to FIG. 7 and is a view for explaining another embodiment. FIG. 9 is a perspective view of a tip mounted on the end mill shown in FIG. 10A to 10E are a rear view, a plan view, a front view, and a right side view of the chip shown in FIG. 9, 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 rectangular 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 is detachable using two screw members 40A and 40B. It is 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, two mounting grooves 20 extending from the distal end surface 10a to the tool proximal end side are 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 10A. Yes. 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.

  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. 9 and 10, 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 on 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 a flat side surface adjacent to the secondary cutting edge rake face 32B, and a central axis of the tool main body is formed at an intersecting ridge line portion between the secondary cutting edge rake face 32B and the secondary cutting edge relief face 33B. A linear sub-cutting edge 31B extending substantially perpendicular to the CL is formed.

  As illustrated in FIG. 9, a pressed portion 35 is formed in a region adjacent to the rake face 32 </ b> A on the upper surface 30 a of the chip 30 and on the long side facing the outer peripheral cutting edge 31 </ b> A. . The pressed portion 35 is slightly depressed from the surface of the upper surface 30a, and is a substantially circular recess 35A, 35B partially cut away in the restrained surface 37 extending from the long side in plan view. The tool body 10 is formed at two locations on both sides with an intermediate point of the entire length of the tip 30 in the central axis CL direction (full length in the longitudinal direction of the tip 30) interposed therebetween. The bottom surfaces 36A and 36B of the recesses 35A and 35B are formed as flat surfaces.

  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.

  On the wall surface side of the mounting groove 20 in the tool body 10 on the tool rotation direction K side, the female screw hole 13A is located at a position facing the bottom surfaces 36A and 36B of the respective recesses that are the pressed portions 35 provided on the top surface 30a of the chip. , 13B are drilled. By screwing the screw members 40A and 40B screwed into the female screw holes 13A and 13B, the screw members 40A and 40B press the bottom surfaces 36A and 36B of the recesses toward the seating surface 34 side of the chip, and the chip 30 is fixed in the mounting groove 20.

  In the state where the tool 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 in the range of 1 to 2 times the diameter D of the outer peripheral cutting edge of the throwaway end mill 1. Is set. Preferably, the outer peripheral cutting edge flank 33A has a twisted surface in the direction along the outer peripheral cutting edge 31A, and is formed so that the outer peripheral flank angle at each position in the direction of the central axis CL is substantially constant. More preferably, the rotation trajectory of the outer peripheral cutting edge 31A formed on the intersecting ridge line between the outer peripheral cutting edge rake face 32A and the outer peripheral cutting edge flank 33A is formed to be substantially parallel to the central axis CL. The corner blade flank 33C where the outer peripheral flank flank 33A and the secondary flank flank 33B intersect has a convex curved surface, and the corner blade 31C corresponding to the corner blade flank 33C includes the outer peripheral blade 31A and the auxiliary cutting blade. The convex curve is smoothly connected to both sides of 31B. 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.

In the throw-away end mill 1 according to the present embodiment, the screw members 40A and 40B do not penetrate the upper and lower surfaces 30a and 30b of the chip 30 and slightly sink from the upper surface 30a of the chip 30 by having the above-described configuration. Since the chip 30 is clamped by pressing the bottom surfaces 36A and 36B of the recesses, as in the conventional tool 1 'shown in FIG. Since the rigidity of the chip 30 is higher than that provided with the hole 35 ′ for receiving ′, the size and thickness of the upper surface and the lower surface 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.

Furthermore, each screw member 40A, 40B presses the chip 30 at two locations spaced on both sides across the midpoint of the entire length of the chip 30 (the total length in the longitudinal direction of the chip 30). In addition, since a large clamping force is obtained, the insert 30 moves in the mounting groove 20 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. In other words, the positioning accuracy of the chip 30 is very good.

  The tip 30 has a simple long and substantially rectangular plate shape, and the shape of the cutting edge and the bottom surfaces 36A and 36B of the recesses are not complicated. Therefore, the conventional tool including the cutting head having a complicated shape 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.

  Furthermore, the pressed portion 35 of the tip 30 is pressed at the position on the tool outer peripheral side as it is located on the tool base end side. That is, as can be seen from FIG. 6 and FIG. 7, the recesses 35A and 35B and the screw members 40A and 40B are provided on the tool outer peripheral side (closer to the outer peripheral cutting edge 31A) as they are closer to the tool base end side. The distance from the center axis CL of 10 to the pressing locations 39A and 39B by the screw members 40A and 40B is larger at Lb on the tool base end side than La on the tool tip end side, and on the tool base end side. The more the tool outer peripheral side, in other words, the position closer to the outer peripheral cutting edge 31A is pressed. As can be seen from FIGS. 5 to 7, the bottom surfaces 36 </ b> A and 36 </ b> B of the respective recesses are formed on the seating surface 34 so that the perpendicular P approaches the two restrained surfaces 37 and 38 as the seating surface 34 is approached. It is inclined with respect to the vertical line, and the inclination angle is in the range of 5 ° to 20 °.

The reason for adopting such a configuration is as follows. In the recess 35B arranged on the tool base end side, the position 39B close to the outer peripheral cutting edge 31A is pressed toward the seating surface 34, so that the chip is attached to the mounting surface 21 and each restraining surface 22 of the mounting groove. , 23, so that the static clamp strength is emphasized. On the other hand, in the concave portion 35A disposed on the tool distal end side, a position 39A farther from the outer peripheral cutting edge 31A than the concave portion 35B disposed on the tool proximal end side is pressed toward the seating surface 34 side. Emphasis was placed on dynamic clamping strength so as to firmly stop the movement of the tip 30 in the cutting resistance direction acting on the outer peripheral cutting edge 31A around the tool outer peripheral opening end SP on the mounting surface 21 of the mounting groove. Is. This is because the cutting resistance tends to increase near the tip of the outer peripheral cutting edge 31A adjacent to the corner blade 31C, and high dynamic clamping strength is required. As described above, regarding the clamp strength of the tip 30, a high static clamp strength is increased on the tool base end side, and a dynamic clamp strength is increased on the tool distal end side, thereby improving the clamping accuracy of the tip 30. The chip 30 is suppressed from vibration and displacement due to cutting resistance during cutting, and stable machining can be performed under high cutting conditions.
In the present embodiment, the pressed portion 35 and the screw members 40A and 40B are each provided in two. However, three or more pressed portions 35 and screw members 40A and 40B may be provided. It is only necessary to provide a position where the pressed portion 35 on the tool base end side is pressed on the tool outer peripheral side.

  The angle formed between the perpendicular P of the bottom surface 36A, 36B of each recess and the perpendicular of the seating surface 34 is in the range of 5 ° to 20 °. When the angle is less than 5 °, the force pressing the chip 30 against the restraining surfaces 22, 23 When the angle exceeds 20 °, the tip 30 is strongly pressed against the restraining surfaces 22 and 23, the tip 30 is lifted from the mounting surface 21, and the tip 30 moves during the cutting process to deteriorate the machining accuracy. This is because there is a possibility of causing problems such as missing blades and breakage of the chip 30.

  Further, in the present end mill 1, it is intended to make point contact between the screw members 40 </ b> A and 40 </ b> B and the recessed portions 35 </ b> A and 35 </ b> B that are the pressed portions 35. That is, as shown in FIGS. 6 and 7, the tip surfaces 41A and 41B of the screw members are formed as flat surfaces orthogonal to the central axis CLs of the screw members, and the central axes CLs of the screw members are formed in the recesses. By being inclined by an angle θ with respect to the perpendicular line P of the bottom surfaces 36A, 36B, it is inclined with respect to the bottom surfaces 36A, 36B and is in contact with these bottom surfaces 36A, 36B at one point. In addition, for the sake of simplicity, the example in which the central axis CLs of each screw member is inclined in the cross section shown in FIGS. 6 and 7 has been described. However, the inclination of the central axis CLs is not particularly limited. However, it is preferably inclined by 2 ° to 8 ° with respect to the perpendicular P in the maximum inclination direction of the perpendicular P of the bottom surface of each recess as viewed from the lower surface 30b of the chip.

  FIG. 8 is a cross-sectional view illustrating another embodiment for realizing point contact between the screw members 40 </ b> A and 40 </ b> B and the pressed portion 35. The tip portions of the screw members 40A and 40B have a conical shape protruding toward the bottom surfaces 36A and 36B of the concave portions, and the apexes of the conical shapes are in point contact. In this aspect, point contact is realized without inclining the central axis CLs of each screw member with respect to the normal of the bottom surfaces 36A and 36B of the respective recesses. The same effect can be obtained when the tip portions of the screw members 40A and 40B are substantially hemispherical protruding toward the bottom surfaces 36A and 36B of the recesses.

  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.

  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. Thus, when the present end mill 1 is applied to the tip 30 having a large overall length in the longitudinal direction, it is extremely effective in increasing the clamping strength of the tip 30, and the cutting in the central axis CL direction is greatly increased. High efficiency cutting can be performed stably. In addition, the effect of improving the rigidity of the tool body 10 is sufficiently exhibited.

  As described above, the throw-away end mill 1 has a configuration suitable for reducing the size of the tip 30 and increasing the clamping strength of the tip 30, thereby stabilizing the cutting process in a small-diameter tool. Since it is extremely effective in achieving the above, a very beneficial effect can be obtained when applied to a throw-away end mill in which the diameter D of the outer peripheral cutting edge is set in the range of 6 mm to 20 mm.

  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 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 FIG. 1, a front view, and a front view side view, respectively. It is an enlarged plan view of the tool front-end | tip part of the throwaway type end mill shown in FIG. It is an enlarged front view of the tool front-end | tip part of the throwaway 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 sectional drawing corresponded in FIG. 7, and is a figure explaining other embodiment. 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. 9, 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)
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 35 Pressed portion 35A, 35B Recessed portion 36A, 36B Recessed bottom surface 37, 38 Constrained surface 40A, 40B Screw member CL Tool body Center axis CLs of female screw hole P

Claims (4)

The tool body rotated around the central axis is formed with at least one mounting groove in the outer peripheral surface of the tip of the tool body, and the chip inserted into the mounting groove is detachable by at least two screw members. A throw-away rotary tool that is mounted, the tip having a long and substantially plate shape is opposed to the rake face formed along the long side of the upper face facing the tool rotation direction and the upper face. A seating surface formed on the lower surface, a flank surface formed on a side surface that intersects the rake surface and faces the outer peripheral side of the tool, and is formed at an intersecting ridge line portion of the rake surface and the flank surface and protrudes from the outer peripheral surface of the tool body. An outer peripheral cutting edge, and a constrained surface formed on at least one of a side surface facing the tool inner peripheral side and a side surface facing the tool base end side, and the mounting surface corresponding to the seating surface and the constrained surface On the wall of the groove The screw that abuts and screwes at least two pressed parts provided on the upper surface of the chip so as to be spaced apart from each other in the direction of the central axis into a female screw hole provided on the wall surface side of the mounting groove facing the upper surface By pressing toward the seating surface side of the tip by a member, the pressed portion of the pressed portion is fixed to the mounting groove by the screw member, and the pressed portion on the tool proximal end side in the central axis direction A throw-away rotary tool characterized in that the part is arranged closer to the outer periphery of the tool. The tool body is provided with a chip pocket extending adjacent to the tool rotation direction side of the mounting groove along the mounting groove, and a wall surface facing the tool outer peripheral side of the chip pocket is formed from the tool distal end side to the tool base end. 2. The throw-away rotary tool according to claim 1, wherein the throw-away rotary tool is formed so as to gradually move away from the central axis as it goes to the part side. The throw-away rotary tool according to claim 1 or 2, wherein the contact between the pressed portion and the screw member is a point contact. The throw-away type according to any one of claims 1 to 3, wherein the length of the outer peripheral cutting edge in the central axis direction is in a range of 1 to 2 times the diameter of the outer peripheral cutting edge. Rotary tool.

Images