JP6618746B2 - Cutting tool insert manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a cutting tool tip that constitutes a blade portion of a cutting tool.

  A so-called insert (throw away tip) is known which is mounted on an insert type (blade tip exchange type) cutting tool to constitute a blade part. Such a chip for a cutting tool is generally formed by pressing a mixture of a raw material powder made of a relatively hard material and a raw material powder serving as a binder phase that binds the hard raw material powder with a mold, Then, it forms by baking. Patent Document 1 proposes forming a raw material by injection molding instead of a press.

Japanese Laid-Open Patent Publication No. 4-283209

  In injection molding, generally, a raw material is injected into a molding die in a state where gas (for example, air) exists in the molding die. The gas in the mold is pushed out by the raw material injected into the mold, and is discharged to the outside of the mold through a so-called vent. At this time, the gas may not be suitably discharged and a gas accumulation may occur. If this gas pool is generated at a position corresponding to the cutting edge in the mold, the cutting edge is chipped.

  Therefore, it is desired to provide a method for manufacturing a cutting tool tip that can improve the formability of the cutting edge in injection molding.

  The method for manufacturing a cutting tool tip according to an aspect of the present invention includes a molding step of obtaining a molded body to be a cutting tool chip by injecting a raw material into a cavity of a molding die, and a heat treatment step of heating the molded body. And an inner surface of the mold that forms one surface of the molded body is provided with a curved recess that recedes toward the outside of the mold.

  Preferably, the molded body has a pair of main surfaces and a side surface connecting the pair of main surfaces, and the concave portion is provided on an inner surface of the molding die forming the side surface of the molded body, and the cavity A gate for injecting the raw material is provided at a position surrounded by the inner peripheral surface of the mold that forms the outer peripheral surface of the molded body including the one side surface.

  Preferably, the molding die includes a plurality of split dies, and a boundary portion between the adjacent split dies is connected to the concave portion.

  Suitably, the said boundary part of the said adjacent division type is connected with the innermost part of the said recessed part.

  Preferably, the manufacturing method includes a step of integrally forming a burr formed by allowing the raw material to enter the boundary portion in the molding step and removing the burr after the molding step.

  Preferably, the step of removing the burr is after the heat treatment step.

  Preferably, the step of removing the burr includes removal by blasting.

  According to said procedure, the moldability of the cutting blade in injection molding can be improved.

The perspective view which shows the insert type cutting tool which concerns on 1st Embodiment of this invention. The perspective view which shows the chip | tip for cutting tools of the cutting tool of FIG. 3A is a cross-sectional view taken along line IIIa-IIIa in FIG. 2, and FIG. 3B is a cross-sectional view taken along line IIIb-IIIb in FIG. The flowchart which shows the outline | summary of the procedure of the manufacturing method of the chip | tip for cutting tools of FIG. Fig.5 (a)-FIG.5 (e) are the schematic diagrams for demonstrating the outline | summary of the procedure of the manufacturing method of the chip | tip for cutting tools. The flowchart which shows the procedure of the injection molding of FIG.5 (b). FIG. 7A to FIG. 7D are schematic views for explaining the injection molding procedure of FIG. Sectional drawing corresponding to FIG. 3 (a) which shows the shaping | molding die used by the injection molding of FIG.5 (b). Sectional drawing corresponding to FIG.3 (b) which shows the shaping | molding die of FIG. The top view of the shaping | molding die of FIG. 11 (a) to 11 (e) are cross-sectional views illustrating burrs in the injection molding of FIG. 5 (b). FIG. 12A is a perspective view showing a cutting tool tip according to a second embodiment of the present invention, and FIG. 12B is a cross-sectional view showing a forming die for the cutting tool tip of FIG. FIG. 13A is a perspective view showing a cutting tool tip according to a third embodiment of the present invention, and FIG. 13B is a sectional view showing a mold for the cutting tool tip of FIG. 13A. FIG. 14A is a perspective view showing a cutting tool tip according to a fourth embodiment of the present invention, and FIG. 14B is a sectional view showing a forming die for the cutting tool tip of FIG.

(How to use terms)
Some terms relating to cutting tools are customarily ambiguous. In the description of the embodiment according to the present invention, such terms are basically used as follows.

  The blade portion is used as a term indicating a relatively small portion (for example, a part of an insert) composed of a rake face, a flank surface, and a cutting edge, and a relatively wide portion (for example, the insert and its surroundings) on the tip side of the cutting tool. The term “part” may be used, but in the description of this embodiment, the former is used.

  The cutting edge may be used as a term indicating a ridge line between a rake face and a flank, and may be used as a term indicating a corner (area or volume part) formed by the rake face and the flank. However, in the description of the present embodiment, the former is assumed. However, the actual cutting blade is not a line microscopically as the term “cutting blade roundness” exists, and the cutting blade has an area or a volume as long as it is.

  The rake face and the flank face mainly refer to portions close to the cutting edge on the main face and the side face, respectively. For example, when the rake face is widely interpreted, the center side of the main surface of the cutting tool insert (hereinafter also simply referred to as a tip) is also a rake face, but such an interpretation is not performed, and the rake face is the main face. It shall refer to the part close to the cutting edge. Note that the flank may or may not include a so-called margin.

<First Embodiment>
(Configuration of cutting tool)
FIG. 1 is a perspective view showing an insert-type cutting tool 1 according to a first embodiment of the present invention.

  The cutting tool 1 is a substantially shaft-shaped member that is attached to and detached from a holder 3 (shank) attached to a machine tool and a tip end side (left side of the paper) of the holder 3 and actually contacts a work piece. And one or more (three in the example of FIG. 1) chips 5 for cutting the work. In the example shown in the drawing, the cutting tool 1 is an end mill, and is capable of cutting a workpiece on the front end surface and the outer peripheral surface of the front end by rotating around the axis.

  The chip 5 is attached to the holder 3 by, for example, screwing a screw 7 inserted through the chip 5 into a female screw portion (not shown) hidden in the chip 5. The holder 3 is formed with, for example, a recess 3r composed of a plurality of surfaces with which a plurality of surfaces (for example, one main surface and two side surfaces) of the chip 5 abut. The chip 5 is positioned by contacting the surface of the recess 3r.

(Chip configuration)
FIG. 2 is a perspective view showing the chip 5. FIG. 3A is a cross-sectional view taken along line IIIa-IIIa in FIG. FIG. 3B is a cross-sectional view taken along line IIIb-IIIb in FIG.

  In FIG. 2 and the like, an orthogonal coordinate system xyz defined and fixed to the chip 5 is attached. In the following description, directions may be described with reference to this coordinate system. Any direction of the chip 5 may be a vertical direction or a horizontal direction, and the dimension in the z-axis direction may be relatively large. However, the z-axis direction is referred to as a vertical direction or a thickness direction. is there. Further, when the chip 5 is simply referred to as a plan view, it refers to viewing in the z-axis direction.

  The chip 5 is formed in, for example, a substantially rectangular parallelepiped shape, and has a pair of main surfaces 9 (upper and lower surfaces) and four side surfaces 11 (two long side surfaces 11L and two long side surfaces 11) connecting the pair of main surfaces 9. Short side surface 11S). In addition, all the side surfaces 11 whole may be called the outer peripheral surface 12. The dimensions of the chip 5 may be set as appropriate. For example, the length of the long side in plan view is 10 mm or more and 16 mm or less, the length of the short side in plan view is 6 mm or more and 10 mm or less, and the thickness is 4 mm or more and 6 mm or less.

(Side shape)
As particularly shown in FIG. 3A, the long side surface 11L located on the long side in the plan view swells outward as a whole in the cross sectional view, for example. In other words, the long side surface 11L has a convex portion in a sectional view. The surface of this convex part is, for example, a curved surface. Note that the curvature of the curved surface may be constant or different with respect to the position in the z direction or the position in the x direction, and the size thereof may be set as appropriate. The position in the z direction at which the convex portion projects outward is, for example, the center position between the pair of main surfaces 9.

  As particularly shown in FIG. 3B, the short side surface 11S located on the short side in the plan view is recessed as a whole so that, for example, the central side in the thickness direction becomes lower in the cross sectional view. From another viewpoint, the short side surface 11S has convex portions 11p on both sides in the thickness direction. The surface of the convex portion 11p is, for example, a curved surface. The curvature of the curved surface may be constant or different with respect to the position in the z direction or the position in the y direction, and the size thereof may be set as appropriate. The position in the z direction at which the convex portion 11p projects outward is, for example, the position of a pair of main surfaces 9 in general.

(Configuration of the blade)
The tip 5 has, for example, a long-side blade portion 13L and a short-side blade portion 13S (hereinafter simply referred to as “blade portion 13” which may not be distinguished from each other) that are directly involved in the cutting of the work material. ing. These blade portions 13 are located at corners of the main surface 9 and the side surface 11. Specifically, the long side blade portion 13L is provided along the long side in plan view, and the short side blade portion 13S is provided along the short side in plan view. The long edge part 13L and the short edge part 13S are connected with corners 21 (nose) at the corners of the long side and the short side in plan view.

  The combination of the long side blade portion 13L and the short side blade portion 13S is provided, for example, on each of the pair of main surfaces 9 and on each of the main surfaces 9 at two corner portions located on one diagonal line. Yes. That is, a total of four combinations of the long side blade part 13L and the short side blade part 13S are provided. In plan view, the diagonal line provided with the blade part 13 on the one main surface 9 side intersects with the diagonal line provided with the blade part 13 on the other main surface 9 side.

  Accordingly, the tip 5 can be used (four times can be used) by rotating the tip 5 by 180 ° around the z-axis and / or by rotating 180 ° around the x-axis. .

  A combination of the plural sets of long side blade portions 13L and short side blade portions 13S has, for example, the same shape. For example, the entire shape of the tip 5 including the blade portion 13 and portions other than the blade portion 13 is 180 ° rotationally symmetric about the z axis and 180 ° rotationally symmetric about the x axis.

  Each blade portion 13 includes a rake face 15 that is a main body for cutting, a flank face 17 that is escaped to avoid unnecessary contact with the finished cutting surface, and a rake face 15 that is a portion where the rake face 15 is connected to the flank face 17. And a blade 19.

  The blade part 13 is formed, for example, so as to protrude in the thickness direction (z-axis direction) with respect to the center side of the main surface 9. Specifically, for example, the rake face 15 is continuous to the center side of the main surface 9 and is formed to rise in the thickness direction at the outer peripheral portion of the main surface 9. Further, for example, the flank 17 is continuous with the side surface 11 and extends beyond the center side of the main surface 9 in the thickness direction. Further, for example, the cutting edge 19 has a height from the center side of the main surface 9 that is higher toward the corner 21 side.

  In the longitudinal section as shown in FIG. 3A or 3B, the presence / absence of the rake face 15 and the flank face 17 with respect to the thickness direction (z-axis direction), the inclination direction and the inclination angle are appropriately set. You can. In the example shown in the figure, the rake face 15 is inclined with respect to the thickness direction so that the cutting edge 19 side is located on the outer peripheral edge side of the main surface 9, and the flank 17 is the center of the main surface 9 on the cutting edge 19 side. It is inclined with respect to the thickness direction so as to be located on the side. The inclination angle with respect to the thickness direction is different from the rake angle and the relief angle. Unlike the illustrated example, for example, the flank 17 may be parallel to the thickness direction, or may be inclined in the thickness direction so as to be positioned on the outer side of the main surface 9 toward the cutting edge 19 side.

  As described above, in the present embodiment, since the blade portion 13 protrudes from the center side of the main surface 9, the tip 5 includes the base portion 23 having the main surface 9 and the side surface 11, and the blade protruding from the base portion 23. It may be perceived as having the portion 13.

(Configuration of mounting holes)
The chip 5 has a mounting hole 25 through which the screw 7 is inserted. As shown in FIGS. 3A and 3B, the mounting hole 25 includes a receiving portion 27 that receives the screw head 7 b of the screw 7 and engages with the screw head 7 b, and a male screw portion 7 a of the screw 7. And an insertion portion 29 to be inserted. The receiving portion 27 is provided on both main surface sides, and the insertion portion 29 is provided therebetween. That is, the screw 5 can be inserted from any one of the pair of main surfaces 9 so that the tip 5 can be rotated 180 ° around the x axis.

  The receiving portion 27 extends while being reduced in diameter from the main surface 9 side to the insertion portion 29 side. The insertion portion 29 is a portion having the smallest diameter in the attachment hole 25. The maximum diameter of the receiving portion 27 is equal to or larger than the diameter of the screw head 7b. Further, the diameter of the insertion portion 29 (minimum diameter of the receiving portion 27) is smaller than the diameter of the screw head 7b and larger than the diameter of the male screw portion 7a. Although not particularly illustrated, the shape of the cross section (xy cross section) of the mounting hole 25 is, for example, a circle at any position in the thickness direction.

  Accordingly, when the screw 7 is inserted into the mounting hole 25 and screwed into a female screw portion (not shown) of the holder 3, the screw head 7b is positioned on the inclined inner surface of the receiving portion 27 according to the diameter of the screw head 7b. Engage with. Further, the male screw portion 7a is inserted into the insertion portion 29 with a predetermined margin (play).

  The inner surface of the receiving portion 27 may be linear when viewed in a longitudinal section, or may be curved, as illustrated in FIGS. 3A and 3B. A part may have a portion parallel to the thickness direction. The depth of the receiving portion 27 is preferably a depth that can accommodate the entire screw head 7b, but may not be such a depth. The inner surface of the insertion portion 29 is, for example, a straight line that is substantially parallel to the thickness direction when the longitudinal section is viewed. However, the inner surface of the insertion portion 29 may be slightly undulated.

(Chip manufacturing method)
FIG. 4 is a flowchart showing an outline of the procedure of the manufacturing method of the chip 5. FIG. 5A to FIG. 5E are schematic diagrams for explaining the outline of the procedure of the manufacturing method of the chip 5. The manufacturing method proceeds in order from FIG. 5 (a) to FIG. 5 (e).

  First, the raw material 31 of the chip 5 is prepared as indicated by reference numeral S301 in FIG. 4 and as shown in FIG. Specifically, for example, a relatively hard raw material powder that is a main component, a raw material powder that is a binder phase component of the hard raw material powder, fluidity is imparted to these raw material powders, and the molded body 35 is shaped. Mixing of organic substances such as a binder for imparting is performed.

  Taking the case where the chip 5 is made of cemented carbide as an example, the raw material powder includes tungsten carbide as a main component, cobalt as a binder component, and tantalum carbide and titanium carbide as additives. Examples of the binder or a role similar to the binder include paraffin or an appropriate type of resin. Note that the tip 5 is not limited to a cemented carbide, but may be, for example, a diamond sintered body, a CBN (Cubic Boron Nitride) sintered body, a narrowly defined ceramic, cermet, or a high-speed tool steel formed by powder metallurgy ( Powder high speed).

  Next, as indicated by reference numeral S302 in FIG. 4 and as shown in FIG. 5B, the raw material 31 of the chip 5 is injected and filled into the molding die 33. The shape in the molding die 33 is substantially the same as that of the molded body to be the chip 5. Therefore, when the injected raw material 31 is solidified in the molding die 33, a molded body 35 (FIG. 5C) having a shape substantially similar to that of the chip 5 is formed.

  Next, as indicated by reference numeral S <b> 303 in FIG. 4 and as shown in FIG. 5C, an unnecessary portion as the chip 5 is removed from the molded body 35 taken out from the molding die 33. The unnecessary portion is, for example, a portion solidified by a so-called sprue and runner (described later). The removal may be performed by an appropriate method, for example, by cutting with a cutter 37.

  Next, as indicated by reference numeral S304 in FIG. 4 and as shown in FIG. 5D, the molded body 35 is fired (a heat treatment step is performed). As a result, a sintered body 39 (FIG. 5E) to be the chip 5 is formed. At this time, the binder added to impart fluidity to the raw material 31 evaporates or burns and is removed from the sintered body 39.

  After that, as indicated by reference numeral S305 in FIG. 4 and as shown in FIG. 5E, the cutting edge of the sintered body 39 is ground or polished (honed) to adjust the roundness of the cutting edge. Thereby, the chip 5 is obtained. Honing is performed, for example, by sandblasting as illustrated in FIG. However, it is not limited to sand blasting, and honing may be performed using, for example, fixed abrasive grains or loose abrasive grains.

  After firing, cutting, grinding, or polishing for removing so-called burrs that occur in injection molding is performed simultaneously with or before and after the above-described honing of the cutting edge. The removal of burrs may also be performed by sandblasting, for example, in the same manner as the honing of the cutting edge. However, the burr may be removed using not only sand blasting but also fixed abrasive grains or loose abrasive grains, for example.

  Note that the above-described procedure is merely an outline of an example of the procedure, and may be modified as appropriate. For example, the removal of unnecessary portions (FIG. 5 (c)) may be after firing (FIG. 5 (d)). Further, for example, after injection molding (FIG. 5B) and before firing (FIG. 5D), a treatment for removing the binder from the molded body (such as calcination and solvent extraction) may be performed. For example, a hard film may be formed after honing (FIG. 5E). Further, for example, the burr removal time may be an appropriate time after injection molding, for example, before firing.

(injection molding)
FIG. 6 is a flowchart showing the injection molding procedure of FIG. Fig.7 (a)-FIG.7 (d) are the schematic diagrams for demonstrating the procedure of the injection molding of FIG.5 (b). Injection molding proceeds in order from FIG. 7 (a) to FIG. 7 (d).

  First, as indicated by reference numeral S401 in FIG. 6 and as shown in FIG. 7A, a plurality of divided dies 41 (FIGS. 7A to 7D show 41A and 41B as a part thereof). The mold 33 made of is closed. Note that the split type here includes, for example, a core or a slide core in addition to a fixed type and a movable type. The plurality of split molds 41 are held by a mold clamping device (not shown), and the mold clamping device moves the split mold 41 by an electric motor or a hydraulic device.

  By closing the mold, a space surrounded by a plurality of divided molds 41 is formed as shown in FIG. The plurality of molds 41 that have been closed are compared by a mold clamping device (not shown) so that no gap is generated between the molds 41 due to the pressure of the raw material 31 when the raw material 31 is injected into the mold 33 later. The mold is clamped with strong force. At this time, an appropriate gas (for example, air) exists in the mold 33.

  After the mold clamping, the injection is performed by an injection device (in a narrow sense) as indicated by reference numeral S402 in FIG. 6 and as shown in FIG. 7C. Specifically, the raw material 31 in the sleeve 43 (cylinder) communicating with the molding die 33 is pushed into the molding die 33 by the plunger 45 in the sleeve 43. The plunger 45 may be a piston or a screw. The injection speed may be set as appropriate, and appropriate shift control may be performed.

  In the process of injecting the raw material 31 into the mold 33, the gas in the mold 33 is appropriately discharged to the outside of the mold 33. For example, a vent (not shown) that communicates the inside and outside of the mold 33 is provided at an appropriate position on the mating surface of the split mold 41, and the gas in the mold 33 is discharged from the vent. The vent depth is, for example, not less than 2 μm and not more than 20 μm. The gas in the molding die 33 may be discharged through a gap between a pin (not shown) that pushes the molding 35 from the split die 41 and the split die 41.

  In FIG.7 (c), a mode that gas is discharged | emitted by the vent not shown is typically shown by arrow y1. In FIG. 7C, gas is exhausted from both sides of the space filled with the raw material 31. However, gas does not need to be discharged from both sides or four sides of the space, and the vent may be provided only on one side with respect to the space.

  As indicated by reference numeral S403 in FIG. 6 and as shown in FIG. 7D, when the raw material 31 is substantially filled in the mold 33, the injection molding is performed from the (narrow sense) injection step to the pressure increase (pressure increase) step. Migrate to That is, the pressure of the raw material 31 in the mold 33 is increased to a predetermined pressure (final pressure) by the pressure applied by the plunger 45. Thereafter, the final pressure is maintained (pressure holding step). The raw material 31 filled in the molding die 33 is solidified by receiving heat from the plunger 45 and depriving the molding die 33 of heat.

  Thereafter, the mold 33 is opened by a mold clamping device (not shown). The molded body 35 remains in one of the plurality of split dies 41 and is pushed out from the split dies 41 by pins (not shown). Then, after the mold 33 is washed, a mold release agent is applied to the mold 33, the next molding cycle is started.

(Configuration of mold)
FIG. 8 is a cross-sectional view corresponding to FIG. FIG. 9 is a cross-sectional view corresponding to FIG. In FIGS. 8 and 9, not only the so-called cross section that is hatched, but also the mating surfaces 47c and 47b of the split mold 41 located behind the cross section are shown. FIG. 10 is a plan view of the mold 33. All of these show the mold 33 in a closed state.

  The molding die 33 is constituted by a mold, for example. As shown in FIGS. 8 and 9, the space formed in the mold 33 that is closed is a cavity 47 that forms a portion to be the chip 5, and the raw material 31 flows into the cavity 47 from the outside of the mold 33. A runner 49 and a sprue 51. Further, the mold 33 has a gate 53 that is an opening for connecting the runner 49 and the cavity 47.

  The shape and dimensions of the cavity 47 are basically the same shape and dimensions as the molded body that becomes the chip 5. That is, the mold 33 has surfaces corresponding to the main surface 9, the side surface 11, the blade portion 13, and the like of the chip 5. Note that the shape and size of the cavity 47 may be slightly different from the shape and size (design value) of the chip 5 in consideration of the effects of firing and honing performed later.

  As described with reference to FIG. 3A, the long side surface 11L of the chip 5 swells outward in a cross-sectional view, and therefore, as shown in FIG. 8, the inner surface of the mold 33 corresponding to the long side surface 11L. Has a recess 47e that recedes outward. Further, as described with reference to FIG. 3B, the short side surface 11S of the chip 5 has the convex portion 11p in the sectional view, and therefore corresponds to the short side surface 11S as shown in FIG. The inner surface of the mold 33 has a recess 47f that recedes outward. Further, since the blade portion 13 protrudes from the center side of the main surface 9, the mold 33 has a recess 47 r that recedes outward from the surface corresponding to the main surface 9.

  The gate 53 is located, for example, in a region surrounded by a plurality of inner surfaces (inner peripheral surfaces) corresponding to the plurality of side surfaces 11 (outer peripheral surfaces 12) of the molding die 33. More specifically, for example, the gate 53 opens at an attachment hole forming surface 33 a corresponding to the inner surface of the attachment hole 25 of the mold 33. The gate 53 is configured as a so-called ring gate, for example, and is open over 360 ° around the z-axis.

  Therefore, the raw material 31 supplied to the runner 49 flows from the center side of the cavity 47 to the outer peripheral side via the gate 53. In other words, it flows from the mounting hole 25 to the plurality of side surfaces 11 (outer peripheral surface 12).

  More specifically, the gate 53 opens, for example, at a position corresponding to the insertion portion 29 of the attachment hole 25 on the attachment hole forming surface 33a. From another viewpoint, the molding die 33 has a protrusion 41p whose surface is a part above or below the attachment hole forming surface 33a, and the protrusion 41p has the shape of the receiving part 27. Correspondingly, it protrudes from the surface corresponding to the main surface 9 of the mold 33 with a reduced diameter, and the gate 53 is located on the tip side of the protrusion 41p.

  The width of the gate 53 in the thickness direction (z-axis direction) of the chip 5 may be set as appropriate. In the illustrated example, the width of the gate 53 in the thickness direction is equal to the size of the insertion portion 29 in the thickness direction. Further, the width in the thickness direction of the gate 53 is, for example, constant in the circumferential direction (over 360 °). Unlike the illustrated example, the gate 53 may correspond to a part of the inner surface of the insertion portion 29 (for example, a part on the center side in the thickness direction), and the width depends on the position in the circumferential direction. May be different.

  For example, the runner 49 is a disk-shaped flow path corresponding to the gate 53 being a ring gate as described above. The size of the runner 49 in the thickness direction (z-axis direction) may be different from that of the gate 53 or may be the same.

  The sprue 51 communicates with the runner 49 and opens at the outer surface of the mold 33. The sprue 51 extends, for example, in the thickness direction (z-axis direction), and is formed in a tapered shape so that the outer side of the mold 33 is reduced in diameter.

  The molding die 33 is divided into, for example, the top, bottom, left and right with respect to the cavity 47, and has a total of four division dies 41. That is, the molding die 33 includes a first main surface split die 41A on one main surface 9 side, a second main surface split die 41B on the other main surface 9 side, and two side surfaces on the two short side surfaces 11S side. And a split type 41C. The sprue 51 described above is provided, for example, in the first main surface split mold 41A. The runner 49 is configured, for example, between the first main surface split mold 41A and the second main surface split mold 41B.

  The first main surface split mold 41A and the second main surface split mold 41B are divided from each other at the center of the cavity 47 in the thickness direction, for example. Moreover, these main surface division | segmentation type | molds (41A or 41B) and the side surface division type | mold 41C are divided | segmented in the position corresponding to the corner | angular part of the long side side surface 11L and the short side surface 11S, for example.

  Accordingly, the first main surface split mold 41A has an inner surface for forming one main surface 9 and an inner surface for forming a portion of the long side surface 11L on the one main surface 9 side. ing. The second main surface split mold 41B has an inner surface for forming the other main surface 9 and an inner surface for forming a portion of the long side surface 11L on the other main surface 9 side. . The side surface split mold 41C has an inner surface for forming the short side surface 11S.

  The first main surface split mold 41A and the second main surface split mold 41B have mating surfaces 47b (FIGS. 8 and 9) that abut each other in the z direction on the inner surface side that forms the long side surface 11L. The mating surface 47b is located, for example, in the center between the inner surfaces of the molding die 33 forming the pair of main surfaces 9 in the z direction, and is a recess 47e for forming a bulge of the long side surface 11L. It is located in the innermost part. In the illustrated example, the mating surface 47b is linear (planar) parallel to the inner surface of the mold 33 forming the main surface 9, but is inclined with respect to the x axis and / or the y axis, It may be bent appropriately.

  The main surface split mold (41A or 41B) and the side surface split mold 41C have a mating surface 47c (FIGS. 8 and 9) that contact each other in the z direction on the inner surface side of the molding die 33 that forms the main surface 9. Yes. For example, the mating surface 47c is located at substantially the same position as the main surface 9 in the z direction, and is located at the innermost portion of the concave portion 47f for forming the convex portion 11p of the short side surface 11S. In the illustrated example, the mating surface 47c is linear (planar) parallel to the inner surface of the mold 33 forming the main surface 9, but is inclined with respect to the x axis and / or the y axis, It may be bent appropriately.

  Further, the main surface split mold (41A or 41B) and the side split mold 41C have a mating surface 47d (FIG. 10) that abuts each other in the direction parallel to the xy plane on the corners of the long side surface 11L and the short side surface 11S. )have. The mating surface 47d has, for example, a planar shape that is positioned approximately at the center between two virtual surfaces that extend from the corners to the intersecting side of the long side surface 11L and the short side surface 11S. The mating surface 47d may be parallel to the long side surface 11L or the short side surface 11S, or may be appropriately bent.

  The mating surfaces (47b to 47d) are basically surfaces on which the split molds 41 come into contact with each other, and ideally there is no gap between the mating surfaces of both split molds 41. However, a relatively small gap may be generated on the cavity 47 side due to wear. In addition, a relatively small gap may be intentionally formed for various purposes.

  The roles of the plurality of split dies 41 in a mold clamping device (not shown) may be set as appropriate. For example, the first main surface division type 41A is a fixed type, the second main surface division type 41B is a movable type, and the side surface division type 41C is a slide core. The slide core may be driven together with the moving type by using an inclined pin or the like, or may be driven by a driving means separate from the moving type. Any direction of the mold 33 may be the vertical direction or the horizontal direction.

(Burr generation)
11 (a) to 11 (c) are cross-sectional views for explaining burrs in injection molding, and correspond to the vicinity of the mating surface 47b on the right side of FIG. The mating surface 47b is described as an example, but the same applies to the mating surfaces 47c and 47d.

  As shown in FIG. 11A, for example, when a situation occurs in which the mold opening force due to the pressure applied to the raw material 31 temporarily increases with respect to the mold clamping force, a gap C1 is generated between the mating surfaces 47b. Then, the raw material 31 flows into the gap C1, and a burr 35b is formed on the molded body 35 as shown in FIG. And the burr | flash 35b is removed by cutting, grinding, or grinding | polishing, as shown in FIG.11 (c). Note that, as described with reference to FIG. 5E, the removal of the burr 35b is preferably performed after firing, and is preferably performed by sandblasting.

  In addition, since the mating surface 47b is located at the innermost part of the recess 47e corresponding to the bulge of the long side surface 11L, for example, the burr 35b formed by the mating surface 47b is located at the top of the long side surface 11L. For example, since the mating surface 47c is located at the innermost part of the concave portion 47f corresponding to the convex portion 11p of the short side surface 11S, the burr 35b formed by the mating surface 47c is located at the top of the convex portion 11p. For example, the mating surface 47d is located at the corners of the long side surface 11L and the short side surface 11S, so the burr 35b formed by the mating surface 47d is located at the corner.

  The gap C1 due to the mold opening may be generated unintentionally, or the gap C1 may be intentionally generated. When the gap C1 is intentionally generated, for example, the speed (injection speed) of the plunger 45 in the injection process (in a narrow sense) is intentionally relatively high at least immediately before the filling is substantially completed, and the so-called surge pressure is compared. You can make it higher.

  FIG.11 (d) and FIG.11 (e) are sectional drawings which show another aspect which the burr | flash 35b is made. The mating surface 47b is described as an example, but the same applies to the mating surfaces 47c and 47d.

  As shown in FIG. 11 (d), in this aspect, a gap C2 is generated on the mating surface 47b, although the mold opening as shown in FIG. 11 (a) is not generated. As a result, as shown in FIG. 11E, burrs 35b are formed. This gap C2 is caused by wear, for example. Alternatively, the gap C2 is intentionally formed.

  When the gap C2 is intentionally formed, the width (the vertical direction in FIG. 11D) is larger than, for example, the gap in other portions (gap caused by wear). Moreover, the width of the intentional gap C2 is, for example, 20 μm or more or 50 μm or more. Since the vent depth is generally 20 μm or more, if the width of the gap C2 is such a size, it can be said that the gap C2 is intentionally formed. The width of the intentional gap C2 is 100 μm or less. If the width of the intentional gap C2 is 100 μm or less, it is easy to remove the burr 35b.

  As described above, the manufacturing method of the cutting tool tip 5 according to the present embodiment is a forming step (FIG. 5) in which the raw material 31 is injected into the cavity 47 of the forming die 33 to obtain the forming body 35 that becomes the cutting tool tip 5. 5 (b)) and a heat treatment step (FIG. 5 (d)) for heating the molded body 35, the inner surface of the molding die 33 forming one surface (side surface 11 in the present embodiment) of the molded body 35 is A curved concave portion 47e or 47f that recedes toward the outside of the mold 33 is provided.

  Therefore, for example, when the raw material 31 is filled in the cavity 47, the gas escape field is constituted by the concave portions 47 e or 47 f, and a gas pool is generated at the corner portion of the molding die 33 forming the cutting edge 19. The fear is reduced. As a result, for example, the risk of chipping of the cutting blade 19 is reduced.

  In the present embodiment, the recess 47 e or 47 f is provided on the inner surface of the molding die 33 that forms the one side surface 11 of the molded body 35. The gate 53 for injecting the raw material 31 into the cavity 47 is provided at a position surrounded by the inner peripheral surface of the molding die 33 that forms the outer peripheral surface 12 of the molded body 35 including the one side surface 11.

  Therefore, for example, the raw material 31 flows from the inside to the outside of the mold 33, while the recess 47e or 47f is located outside the mold 33, so that gas easily escapes to the recess 47e or 47f. As a result, for example, the risk of gas accumulation at the corners forming the cutting edge 19 is further reduced.

  Moreover, in this embodiment, the shaping | molding die 33 contains the some division mold 41, and the boundary part (matching surface 47b or 47c) of the adjacent division mold 41 is connected with the recessed part 47e or 47f.

  Therefore, for example, when the raw material 31 is filled in the cavity 47, the gas escaped to the recess 47e or 47f is discharged to the outside through the boundary portion or escapes to the nearby vent through the boundary portion. Is possible. As a result, for example, an increase in the pressure of the recess 47e or 47f is suppressed, and the gas is more likely to escape to the recess 47e or 47f, and there is a possibility that a gas pool is generated at the corner portion of the mold 33 forming the cutting edge 19. Reduced. Further, for example, since the gas escaped to the concave portion 47e or 47f escapes to the boundary portion, a gas pool is generated on the side surface 11, and the possibility that an unintended concave portion is formed on the side surface 11 is also reduced. For example, the strength of the chip 5 is ensured by reducing the possibility that an unintended recess is formed in the side surface 11.

  In the present embodiment, the boundary portion (the mating surface 47b or 47c) of the split mold 41 is connected to the innermost portion of the recess 47e or 47f.

  Accordingly, for example, the molded body 35 can be taken out by separating the split mold 41 with the top of the side surface 11 of the molded body 35 as a boundary. That is, so-called undercut does not occur, and the number of split molds 41 can be reduced. In addition, since the gas escapes from the innermost part, the flow of the raw material 31 tends to be a natural flow toward the innermost part, which stabilizes the flow of the raw material 31 and, in turn, stabilizes the accuracy of the chip 5. it can.

  Further, in the present embodiment, a burr 35b formed by allowing the raw material 31 to enter the boundary portion (mating surface 47b or 47c) in the molding step (FIG. 5B) is formed integrally with the molded body 35, and the manufacturing method is as follows. And a step of removing the burr 35b after the molding step (FIGS. 5E and 11C).

  Therefore, for example, the raw material 31 is filled up to the gaps C1 and / or C2 beyond the inner surface forming the side surface 11 of the mold 33, and the risk of gas accumulation on the side surface 11 can be reliably reduced. The burr 35b is normally not preferable, and its formation is suppressed. Such burr 35b is intentionally formed to suppress the occurrence of gas accumulation, and this embodiment is epoch-making.

  The burr 35b is not necessarily removed by the manufacturer of the chip 5. For example, when the burr 35b is very small or the position where the burr 35b is formed is a position that does not affect the positioning of the chip 5, even if the chip 5 is used without removing the burr 35b. Good. Further, for example, the burr 35b may be polished and removed by the user of the chip 5.

  In the present embodiment, the step of removing burrs (FIGS. 5E and 11C) is after the heat treatment step (FIG. 5D).

  Therefore, for example, compared with the case where grinding or polishing is performed on the relatively soft molded body 35 before firing, the possibility that the chip 5 is deformed when the burr is removed is reduced. As a result, the accuracy of the cutting edge 19 and the like is improved. On the contrary, when the step of removing the burr 35b is performed before firing unlike the embodiment, for example, since the burr 35b is softer than before sintering, various removal methods can be applied. is there.

  In the present embodiment, the step of removing the burr 35b (FIG. 5E) includes removal by blasting.

  Therefore, the burr 35b can be removed easily and accurately while suppressing deformation of the chip 5. Further, it is suitable for common use of removal of the burr 35b and honing of the cutting edge 19.

<Other embodiments>
In the first embodiment, the chip 5 that is rectangular in a plan view and that constitutes an end mill is taken as an example. However, the effective inner surface shape of the mold 33, the position of the mating surface, the gate position, and the like of the first embodiment can be applied to other various cutting tool tips. Below, some are illustrated.

Second Embodiment
FIG. 12A is a perspective view showing a cutting tool tip 205 according to the second embodiment of the present invention.

  The chip 205 is a substantially triangular chip in plan view, and is used, for example, as a bite chip. The tip 205 has a pair of main surfaces 209 and three side surfaces 211, and three blade portions 213 are formed at corners of one of the pair of main surfaces 209 and the three side surfaces 111. ing. Note that three blade portions 213 may also be formed at the corners of the other main surface 209 and the three side surfaces 111.

  The blade portion 213 includes, for example, a rake face 215 made of a land parallel to the central portion of the main surface 209, a flank 217 formed by the side surface 211, and a cutting blade 219 that is an intersection of these. ing. Thus, the blade part 213 may be comprised by the corner | angular part of the main surface or side surface, or a surface parallel to these, without protruding with respect to a main surface or a side surface.

  The side surface 211 is, for example, a linear shape in a plan view, but is configured in a curved shape that swells outward in a longitudinal sectional view. The curvature and the like may be set appropriately as in the first embodiment. For example, the top of the side surface 211 is located at the center between the pair of main surfaces 209 in the thickness direction of the chip 205.

  The chip 205 has a mounting hole 225. Although not particularly shown, the mounting hole 225 has a receiving portion with which the screw head 7b of the screw 7 is engaged and an insertion portion into which the male screw portion 7a of the screw 7 is inserted, as in the first embodiment. . However, the receiving portion is provided only on the main surface 209 side where the blade portion 213 is provided in correspondence with the blade portion 213 being provided on only one of the pair of main surfaces 209 ( (Refer to the shaping | molding die 233 of FIG.12 (b)).

  FIG. 12B is a cross-sectional view of a molding die 233 for forming a molded body to be the chip 205, and corresponds to the XIIb-XIIb line in FIG.

  A cavity 247 corresponding to the chip 205 and a runner 249 communicating with the cavity 247 are formed inside the mold 233. The side surface of the cavity 247 (the inner surface of the mold 233 that forms the side surface 211) has a recess that recedes outward in response to the side surface 211 expanding. Further, the gate 253 connecting the cavity 247 and the runner 249 is formed in a ring shape in a region corresponding to the insertion portion of the mounting hole forming surface 233a that forms the inner surface of the mounting hole 225, for example, as in the first embodiment. Is provided.

  In the present embodiment, the insertion portion (the portion having a constant diameter in the penetrating direction) of the mounting hole 225 extends to the main surface 209 where the blade portion 213 is not formed, and the gate 253 is positioned at an appropriate position thereof. May be provided. For example, as illustrated, the cavity 247 may be provided on the center side in the thickness direction, and unlike the illustrated example, it is close to a surface corresponding to the main surface 209 where the blade portion 213 is not provided. It may be provided at a position.

  In addition, as in the first embodiment, for example, the molding die 233 is divided vertically at a substantially center in the vertical direction, and includes a first main surface division die 241A and a second main surface division die 241B. Note that, since the chip 205 of this embodiment does not have the side surface 211 having a recess in the longitudinal sectional view, unlike the first embodiment, the side surface split type is unnecessary. The mating surface 247b (boundary portion) of the first main surface split mold 241A and the second main surface split mold 241B is located at the innermost portion of the concave portion of the inner surface forming the side surface 211, for example, as in the first embodiment. ing.

<Third Embodiment>
FIG. 13A is a perspective view showing a cutting tool tip 305 according to a third embodiment of the present invention.

  The chip 305 is a substantially hexagonal chip in plan view, and is used, for example, as a front milling chip. The chip 305 has a pair of main surfaces 309 and six side surfaces 311, and twelve blade portions 313 are formed at corners of the pair of main surfaces 309 and the six side surfaces 311. Yes.

  The hexagon has a 120 ° rotationally symmetric shape, and three corners at 120 ° rotationally symmetric positions are made smaller than the other three corners. Two cutting edges 319 connected by a corner 321 located at a relatively small corner are used simultaneously. That is, the tip 305 can be used six times by replacing the cutting blade 319 to be used.

  For example, the blade portion 313 is formed so as to protrude in the thickness direction (up and down direction in FIG. 13A) from the center side of the main surface 309, as in the first embodiment. That is, the rake face 315 extends from the central side of the main surface 309 and extends so as to rise at the outer peripheral portion of the main surface 309, and the flank 317 continues from the central region in the thickness direction of the side surface 311 and the main surface. The cutting edge 319 extends beyond the center side of the main surface 309, and is higher than the central side of the main surface 309.

  For example, the side surface 311 is linear in a plan view, but is configured in a curved shape that bulges outward in a longitudinal sectional view. The curvature and the like may be set appropriately as in the first embodiment. For example, the top of the side surface 311 is located at the center between the pair of main surfaces 309 in the thickness direction of the chip 305.

  The chip 305 has a mounting hole 325. Although not particularly illustrated, the mounting hole 325 includes a receiving portion with which the screw head 7b of the screw 7 is engaged and an insertion portion into which the male screw portion 7a of the screw 7 is inserted, as in the first embodiment. The part is provided on both main surfaces 309 side with respect to the insertion part.

  FIG. 13B is a cross-sectional view of a molding die 333 for forming a molded body to be the chip 305, and corresponds to the XIIIb-XIIIb line in FIG.

  A cavity 347 corresponding to the chip 305 and a runner 349 communicating with the cavity 347 are formed inside the mold 333. The side surface of the cavity 347 (the inner surface of the mold 333 that forms the side surface 311) has a recess that recedes outward in response to the side surface 311 expanding. The gate 353 that connects the cavity 347 and the runner 349 is provided in a ring shape in a region corresponding to the insertion portion of the mounting hole forming surface 333a that forms the inner surface of the mounting hole 325, for example, as in the first embodiment. ing.

  In addition, as in the first embodiment, for example, the molding die 333 is divided vertically at a substantially center in the vertical direction, and includes a first main surface split die 341A and a second main surface split die 341B. Since the chip 305 of the present embodiment does not have the side surface 311 having a recess in the longitudinal sectional view, unlike the first embodiment, the side surface split type is unnecessary. The mating surface 347b (boundary part) of the first main surface split mold 341A and the second main surface split mold 341B is located at the innermost part of the concave portion of the inner surface forming the side surface 311 as in the first embodiment, for example. ing.

<Fourth embodiment>
FIG. 14A is a perspective view showing a cutting tool tip 405 according to the fourth embodiment of the present invention.

  In the first to third embodiments described above, the cutting blade is positioned at the corner between the main surface and the outer peripheral surface, whereas in the tip 405, the cutting blade is positioned on the outer peripheral surface. Also in such an aspect, the above-described concave portion of the mold, the position of the mating surface, and the like can be applied. Specifically, it is as follows.

  The chip 405 is a substantially triangular chip in a plan view, and is used as a chip for a grooving (parting) tool, for example. The tip 405 generally has a pair of main surfaces 409 and three side surfaces 411 (outer peripheral surface 412), and has three blade portions 413 at corners of the three side surfaces 411.

  The blade portion 413 includes, for example, a concave rake face 415 positioned on the corner side of one side face 411, and a relief face 417 that is a part formed by chamfering another side face 411 continuous to the rake face 415, It has a cutting edge 419 located at the intersection of the rake face 415 and the flank face 417. The cutting edge 419 extends in the thickness direction of the tip 405. As described above, the blade portion 413 is positioned not on the corner portion between the main surface 409 and the outer peripheral surface 412 but on the outer peripheral surface 412 (corner portion between the side surfaces 411).

  For example, the side surface 411 is linear in a plan view, but is configured in a curved shape that bulges outward in a longitudinal sectional view. The curvature and the like may be set appropriately as in the first embodiment. For example, the top of the side surface 411 is located at the center between the pair of main surfaces 409 in the thickness direction of the chip 405.

  The chip 405 has a mounting hole 425. Although not particularly illustrated, the mounting hole 425 includes a receiving portion with which the screw head 7b of the screw 7 is engaged and an insertion portion into which the male screw portion 7a of the screw 7 is inserted, as in the first embodiment. . However, the receiving portion is provided only on one main surface 409 side (for example, the front side of the paper in FIG. 14A) with respect to the insertion portion, for example, as in the second embodiment.

  FIG. 14B is a cross-sectional view of a molding die 433 for forming a molded body to be the chip 405, and corresponds to the XIVb-XIVb line in FIG.

  A cavity 447 corresponding to the chip 405 and a runner 449 communicating with the cavity 447 are formed inside the mold 433. The side surface of the cavity 447 (the inner surface of the mold 433 that forms the side surface 411) has a recess that recedes to the outside in response to the side surface 411 expanding. The gate 453 that connects the cavity 447 and the runner 449 is provided in a ring shape in a region corresponding to the insertion portion of the mounting hole forming surface 433a that forms the inner surface of the mounting hole 425, for example, as in the first embodiment. ing. As in the second embodiment, the gate 453 may be provided at an appropriate position in the insertion portion extending from the receiving portion to the main surface opposite to the receiving portion. In the illustrated example, the cavity 447 is provided on the center side in the thickness direction.

  Further, for example, as in the other embodiments, the molding die 433 is divided into upper and lower parts at approximately the center in the vertical direction, and has a first main surface division mold 441A and a second main surface division mold 441B. Note that the chip 405 of the present embodiment does not have the side surface 411 having the concave portion in the longitudinal sectional view, and therefore, unlike the first embodiment, the side surface split type is unnecessary. The mating surface 447b (boundary part) of the first main surface split mold 441A and the second main surface split mold 441B is connected to the innermost part of the concave portion of the inner surface forming the side surface 411, for example, as in the first embodiment. Yes.

  In addition, this invention is not limited to the above embodiment, You may implement in a various aspect.

  For example, the tip is not limited to an insert (throw away tip), and may be brazed to a shank. Further, when the chip is an insert, the method for attaching to and detaching from the holder is not limited to using a screw, and may be a clamp or a combination of a screw and a clamp. The chip may have no mounting hole. The mounting hole may not have a taper portion (screw receiving portion).

  The shape of the chip may be an appropriate shape such as a circle, a rhombus, a square, a pentagon, and an octagon other than those exemplified in the embodiment. The number of cutting blades is not limited to a plurality, and may be one. The presence or absence of the chip breaker and its shape may be set as appropriate. Any of the right hand, left hand, and both hands may be used. As mentioned in the embodiment, the material of the chip is also arbitrary.

  The inner surface of the mold that is formed with the recess that recedes outward is not limited to the inner surface that forms the side surface of the chip, but may be the inner surface that forms the main surface of the chip. Further, as will be understood from the first embodiment, the concave portion may swell the main surface or the entire side surface of the chip, or may locally swell the main surface or the side surface of the chip. It may be.

  The boundary portion (mating surface) may not communicate with the concave portion of the mold. For example, in the second embodiment, a molding die is configured by a total of five split dies, that is, three side split molds corresponding to three side faces and two main face split molds corresponding to two main faces, and the boundary portion May be located at the corner of the chip. Further, when the boundary portion communicates with the concave portion of the mold, the boundary portion may communicate with a position other than the innermost portion of the concave portion.

  The gate may not be located on the inner surface of the mounting hole (the surface of the mold corresponding to the inner surface). For example, the gate may be located on the outer peripheral surface of the chip, or may be located on the main surface of the chip.

  DESCRIPTION OF SYMBOLS 1 ... Cutting tool, 5 ... Chip for cutting tool, 9 ... Main surface, 11 ... Side surface, 12 ... Outer peripheral surface, 19 ... Cutting blade, 25 ... Mounting hole, 31 ... Raw material, 33 ... Mold, 33a ... Formation of mounting hole Surface, 35 ... Molded body, 39 ... Sintered body, 41 (41A to 41C) ... Dividing mold, 47 ... Cavity, 47a ... Intersection, 47b ... Mating surface (boundary part), 47r ... Recess, 53 ... Gate.

Claims (5)

A molding step of obtaining a molded body to be a cutting tool chip by injecting a raw material into a cavity of a molding die;
A heat treatment step of heating the molded body,
The molded body has a pair of main surfaces and an outer peripheral surface connecting the pair of main surfaces,
The mold includes a plurality of divided molds,
The plurality of divided types are:
A pair of principal surface split types facing each other, including inner surfaces forming the pair of principal surfaces;
Including a side surface split mold as a slide core, including an inner surface forming a side surface included in the outer peripheral surface;
The inner surface of the mold that forms one surface included in the outer peripheral surface is provided with a curved recess that recedes toward the outside of the mold in a cross section parallel to the opposing direction of the pair of main surface split molds. And
The innermost part of the concave portion is separated from the pair of inner surfaces forming the pair of main surfaces in the molding die in the facing direction.
The boundary part which divides | segments the said shaping | molding die in the said opposing direction between the said adjacent division | segmentation dies is connected with the said innermost part of the said recessed part. The manufacturing method of the chip | tip for cutting tools.   The manufacturing method of the tip for cutting tools of Claim 1 with which the gate for inject | pouring the said raw material in the said cavity is provided in the position enclosed by the internal peripheral surface of the said shaping | molding die which forms the said outer peripheral surface. . In the molding step, a burr formed by infiltrating the raw material into the boundary portion is formed integrally with the molded body,
The manufacturing method of the tip for cutting tools of Claim 1 or 2 including the process of removing the said burr | flash after the said formation process. The method for manufacturing a cutting tool tip according to claim 3, wherein the step of removing the burr is after the heat treatment step.   The method for manufacturing a cutting tool tip according to claim 3 or 4, wherein the step of removing the burr includes removal by blasting.

Images