JP2008036755A - Small diameter joined end mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small diameter joined end mill which eliminates deviance by approximately aligning central axes of a compound sintered member and a shank, and can reduce manufacturing cost. <P>SOLUTION: In an end mill, a hole is formed at one end of the shank and the compound sintered member is fitted and brazed. The hole is formed to be a polygon having four sides or more in a section perpendicular to an axis, the end of the compound sintered member abuts on the four sides or more of the polygon of the hole, and each part whose side crosses the side has a brazing filler metal reservoir 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a small-diameter joining end mill formed by fitting and brazing a shank and a composite sintered member.

In recent years, with the miniaturization and higher hardness of molds and parts, high-diameter sintered materials, mainly small cubic boron nitride sintered materials (hereinafter referred to as CBN) and diamond sintered materials are used for blades. A joining end mill is used. The small-diameter joining end mill is composed of a composite sintered member made of a material having a different blade part and the remaining part and a shank provided separately, and is joined by fitting the end of the composite sintered member into a hole provided in the shank. Composed. An example in which the cross-sectional shape of the end portion of the composite sintered member inserted into the shank hole portion of such a small-diameter joining end mill is circular is described in Patent Document 1, and an example in which a polygonal shape is used is Patent Document 2. It is described in.
JP 2002-307227 A JP 2004-268202 A

However, in the end mill described in Patent Document 1, the cross-sectional shape of the end portion and the hole portion is similar, and there is a clearance between the end portion and the hole portion so as to fill the row. It is eccentrically brazed and joined. For this reason, when machining the blade and neck with the shank center axis as the reference after brazing, the blade and neck may not be machined. To avoid this, the blade and neck must be combined for machining in advance. A lot of machining allowance is taken for the sintered member. Therefore, the manufacturing time of the small diameter joining end mill has increased. Similarly, the end mill of Patent Document 2 also joins the cross-sectional shape of the end portion and the hole portion in a similar shape, and the rotation center of the shank hole portion and the composite sintered member do not coincide with each other, resulting in an increase in manufacturing time. It was.
The present invention solves the above problem, and an object of the present invention is to provide a small-diameter joining end mill that can eliminate the deviation by making the central axes of the composite sintered member and the shank substantially the same, and reduce the manufacturing cost.

In order to achieve the above object, the present invention provides an end mill in which a hole is provided at one end of a shank and a composite sintered member is fitted and brazed, and the hole has multiple sides in a cross section perpendicular to the axis. The composite sintered member has a square shape, and the end portions of the composite sintered member are in contact with four or more sides of the polygon of the hole, and each portion where the sides intersect is provided with a low pool. Thereby, the shift | offset | difference of the center axis | shaft of a composite sintered member and a shank can be suppressed, the grinding allowance at the time of a blade part and a neck part process can be provided small, and manufacturing time can be shortened.
Moreover, in this invention of the said structure, it is preferable to provide a high-hardness sintered member in the other end of the said composite sintered member, and to make the remainder and the said shank the cemented carbide. Thereby, the bending by the grinding resistance of the end mill itself can be suppressed and manufacturing can be performed with high accuracy. The polygon of the hole or the end of the composite sintered member is preferably a regular polygon having four or more sides. Thereby, the part which a hole part and an edge part contact | abut can be arrange | positioned with sufficient balance to an end mill rotation direction, and the shift | offset | difference of the center axis | shaft of a composite sintered member and a shank can be suppressed. Furthermore, it is preferable that each of the holes or ends that fit into the regular polygon is longer than the side of the regular polygon. Thereby, the length which each side of the polygon of a hole part and an edge part contacts can be taken to the maximum, and it can join accurately.

  By applying the invention of the present application, it was possible to provide a small-diameter joining end mill that can increase the joining accuracy, reduce the grinding allowance of the neck and blade, and reduce the manufacturing time.

Hereinafter, the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the intermediate member 1 that is the origin of the small-diameter joining end mill of the present invention is a CBN portion of the composite sintered member 2 in the composite sintered member 2 having one end made of CBN and the other end made of cemented carbide. The blade portion forming portion 3, the cemented carbide portion being the neck portion forming member 4, and the end portion of the composite sintered member 2 being brazed and fixed to the shank 5 provided separately from the composite sintered member 2 It has six. The small-diameter joining end mill of the present invention is obtained by cylindrically grinding the outer periphery of the neck forming member 4 to a predetermined diameter with the shank 5 as a reference to form the neck, and then machining the blade into the blade forming part 3. . For example, as shown in FIG. 2, the composite sintered member 2 is cut by wire cutting from a material plate obtained by integrally sintering an ultra-high hardness sintered material 8 on the upper surface of a disk-shaped cemented carbide material 7. It is obtained with.
As shown in FIG. 3, the present invention forms a polygon having four or more sides in the shape of the end of the neck forming member 4 and the hole of the shank 5 in a cross-sectional view perpendicular to the axis of the joint 6. Each side of the hole portion comes into contact with the end surface to form a fitting portion 9, and each portion where each side intersects forms a low pool 10 to join the composite sintered member 2 and the shank 5. In the present invention, the end portions of the composite sintered member abut on four or more sides of the polygon of the hole, so that the central axes of the composite sintered member 2 and the shank portion 5 are substantially the same without biasing the brazing material. It is possible to provide good bonding, and when processing the blade forming part 3 and the neck forming member 4, it is possible to reduce the grinding allowance of the ultra-high hardness sintered material that is difficult to grind, and the manufacturing time Can be shortened. Here, it is not necessary for the abutment to be in contact with four or more sides of the polygonal portion of the end portion and the hole portion, and it is sufficient that they are fitted with a fitting tolerance. If the shape of the hole is a polygon consisting of three sides, the number of low pools 10 is small and the bonding strength is reduced. Further, the grinding allowance varies greatly during the processing of the neck portion and the blade portion, and the grinding efficiency cannot be increased.

  In the present invention, it is preferable that a high-hardness sintered member is provided at the other end of the composite sintered member, and the remainder and the shank are made of cemented carbide. Thereby, the edge part and the shank 5 of the composite sintering member 2 can endure the heating at the time of brazing, and can maintain joint strength. Further, at the time of manufacturing, the neck and the shank 5 can be provided with a cemented carbide having good grindability, and the small diameter joining end mill of the present invention can be manufactured with high efficiency. As the high hardness sintered member, CBN or diamond sintered material is preferable, and an end mill excellent in wear resistance can be obtained.

  Furthermore, the polygon of the hole or the end of the composite sintered member is preferably a regular polygon having four or more sides. Thereby, the fitting part 9 with which each edge | side of a hole part contact | abuts the surface of an edge part, and the low pool 10 can be arrange | positioned with sufficient balance in an end mill circumferential direction. Therefore, each side of the hole portion can be brought into contact with the end surface evenly, and the composite sintered member 2 can be prevented from collapsing with respect to the shank 5 to obtain good joining accuracy, and the blade portion, neck portion can be obtained. The fluctuation of the grinding allowance can be suppressed at the time of machining, the burden on the grinding wheel is reduced, and the manufacture becomes easy. In addition, since the low reservoir 10 can be arranged evenly, resistance in the direction of rotation of the end mill can be evenly received during manufacturing or use as an end mill, and the bonding strength can be ensured.

  In the present invention, it is preferable that the hole or end fitted into the regular polygon has a longer side in contact with the side of the regular polygon. Thereby, the length which each side of the polygon of a hole part and an edge part contacts can be taken to the maximum, and it can join accurately. Further, the rotational moment of the end mill can be received on a long side, and the bonding strength is increased. Furthermore, compared with the case where the length of the side is the same, it is easy to fit the end portion into the hole portion.

  The present invention is preferably applied to an end mill having a blade diameter of 1 mm or less. Even if the rigidity is low, it can be manufactured with a small grinding allowance, suppresses bending due to grinding resistance, and does not reduce efficiency. Moreover, as shown in FIG. 3, it is preferable to provide the thickness 11 of the brazing material of the low reservoir 10 in the range of 0.03 mm to 0.08 mm. The thickness 11 of the brazing material is a clearance in the end mill radial direction between the polygonal sides of the hole portions forming the low pool 10 and the surfaces of the end portions and the end surfaces. Can be bonded to the shank 5 with sufficient strength. Here, when the thickness 11 of the brazing material is less than 0.03 mm, it is not possible to obtain sufficient strength for joining the end portion and the hole portion of the brazing material, and it is possible to peel by receiving grinding resistance or cutting resistance. There is sex. Further, if the thickness of the brazing material exceeds 0.08 mm, the brazing material may be deformed and peeled when the grinding resistance or cutting resistance acts on the joint 6. The thickness 11 of the brazing material is preferably uniform within a range of 50% or more with respect to the length in the end mill circumferential direction of each portion where the sides intersect each other in the polygon of the hole. Hereinafter, the present invention will be described based on examples.

(Example 1)
As Example 1 of the present invention, a hole is provided at one end of a shank 5 made of a cemented carbide. From FIG. 3, the hole is provided in a polygonal shape consisting of four sides, and the distance L1 between the opposing sides of the hole is 1. It was provided at 1 mm. Next, a low pool 10 is provided in each of the parts having tolerances on the four sides, and has a substantially octagonal shape. From FIG. 4, the axial depth L2 of the shank of the hole was set to 2 mm. Composite sintering is carried out by a wire-cut electric discharge machine from a material plate obtained by integrally sintering a super-hard sintered material 8 (CBN sintered pair is used in this embodiment) and a cemented carbide material 7 shown in FIG. Member 2 was cut out. The cut-out shape is a regular octagonal column having a size in which a circle having a diameter of 1.08 mm, that is, a diameter of 1.08 mm is inscribed in FIG. The length L3 is 6 mm. The cross-sectional shape of the hole portion of the shank 5 and the cross-sectional shape of the end portion of the composite sintered member 2 were provided in a non-similar shape. Then, the end portion of the composite sintered member 2 is inserted into the hole portion of the shank and fitted and brazed, and the four opposite sides of the hole portion are in contact with the surface of the end portion of the composite sintered member 2 and the fitting portion 9. Each portion where each side intersects forms a low pool 10 with the end surface of the composite sintered member 2 and a flat portion. As the brazing material, a silver-containing silver solder having a high melting point and easily wetted with the cemented carbide was used. Further, for fitting between the hole and the end, a clearance of 0.01 mm per side is provided on the four sides facing the hole with respect to the abutting end, and the thickness 11 of the brazing material of the low pool 10 is 0. .05 mm.
As a comparative example 2, the cross-sectional shape of the hole portion is a regular octagon, that is, a similar shape to the cross-sectional shape of the end portion, with the same specifications as in the first invention example. A gap was formed to fill the material, and the gap was made 0.05 mm.

  Invention Example 1 and Comparative Example 2 were subjected to a ball end mill production test. As a test, the shank 5 is gripped by a chuck of a grinding machine, the neck portion forming portion 4 of the composite sintered member 2 is ground into a cylinder having a diameter of 1.03 mm, and then the blade portion forming portion 3 is a ball blade having a blade diameter of 1 mm. A ball end mill having a total length of the blade part and the neck part of 4 mm was manufactured by grinding into a mold. The grinding wheel used for grinding is diamond whose abrasive grains are diamond and the binder is resinoid bond. The grinding condition is that the peripheral speed of the outermost circumference of the grinding wheel is 2000 m / min, and the grinding allowance is one end mill radius. The thickness was set to 0.025 mm, and grinding was performed using a water-soluble grinding fluid. As an evaluation, the cylindrical grinding of the neck portion forming portion 4 and the ball blade type grinding state of the blade portion forming portion 3 were observed at a magnification of 20 times using an optical microscope. As a result, when the neck portion forming portion 4 of the composite sintered member 2 of Example 1 of the present invention was cylindrically ground to a diameter of 1.03 mm, the grinding allowance was as small as 0.025 mm, but there was no uncut residue, The entire outer periphery of the neck portion forming portion 4 could be ground. Further, when the blade portion forming portion 3 was processed into a ball end mill blade shape, the deflection of the blade shape was measured and found to be within 3 μm, and good blade shape accuracy was obtained. When Comparative Example 2 was cylindrically ground to a diameter of 1.03 mm in the same manner as in Invention Example 1, a part of the surface of the composite sintered material could not be ground and the cylinder could not be finished. Also in the cutting of the blade part, the grinding allowance varied, and it was not possible to apply a blade to a part of the ball blade, and the fluctuation of the blade mold exceeded 3 μm. This is good because the center axis of the composite sintered member 2 cannot coincide with the center axis of the shank, and misalignment or collapse occurs during brazing, and the composite sintered material swings against the shank. It is thought that it was not possible to perform proper cylindrical grinding and blade attachment. As a result, according to the present invention, the minimum grinding allowance can be set, the manufacturing time can be shortened, and the manufacturing cost can be reduced.

(Example 2)
As the present invention example 3, the length of each side of the four sides of the hole portion of the shank 5 is the same as that of the present invention example 1 with respect to the length of the regular octagonal side of the end of the composite sintered member 2. Example 1/2 was prepared, Example 3 was provided as Example 4 of the invention, Example 4 was provided as Example 5 of the invention, Example 5 was provided as Example 6 of the invention, and Example 1 was subjected to the same test.
As a result, when the length of each of the four sides of the hole portion of the shank 5 is longer than or equal to that of the same, the grinding amount variation between the front end side and the end side of the composite sintered member 2 is small, The joining accuracy was good.

FIG. 1 shows a front view of a small-diameter joining end mill according to the present invention. FIG. 2 shows an example of a material plate. FIG. 3 is a cross-sectional view taken along line WW in FIG. FIG. 4 shows a perspective view of the shank. FIG. 5 shows a perspective view of the intermediate member. FIG. 6 shows another embodiment of the present invention and shows a cross-sectional view similar to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Intermediate member 2 Composite sintered member 3 Blade part formation part 4 Neck part formation member 5 Shank 6 Fitting part 7 Cemented carbide material 8 High hardness sintered material 9 Fitting part 10 Low pool 11 Thickness of raw material L1 Each facing Distance between sides L2 Axial depth of shank of hole L3 Axial length

Claims (4)

In the end mill formed by providing a hole at one end of the shank and fitting and brazing the composite sintered member, the hole forms a polygon having four or more sides in a cross section perpendicular to the axis, A small-diameter joining end mill characterized in that an end portion is in contact with four or more sides of the polygon of the hole portion, and each portion where the side intersects is provided with a low pool. 2. The small-diameter joining end mill according to claim 1, wherein a high-hardness sintered member is provided at the other end of the composite sintered member, and the remainder and the shank are made of cemented carbide. 3. The small diameter joining end mill according to claim 1 or 2, wherein the polygon of the hole or the end of the composite sintered member is a regular polygon having four or more sides. 4. The small-diameter joining end mill according to claim 3, wherein each of the holes or ends fitted into the regular polygon is longer than the regular polygon.

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