JPH01216710A - End mill and manufacture thereof - Google Patents

Abstract

PURPOSE:To make the boundary section between the processing face by an outer peripheral edge and the processing face by a bottom edge a right angle by cutting a gash to the edge back of the outer peripheral edge on the primary end mill formed in a taper shape so that the tip section of the edge section is expanded in diameter toward the tip side. CONSTITUTION:The primary end mill 1 is formed in a taper shape so that the tip section 3 of the edge section 2 is expanded in diameter toward the tip side. The axial length (1) is generally made about 0.01-0.3 times the nominal diameter size, the size D at the maximum diameter portion is generally made about 0.005-0.15times the nominal diameter size. A gash is cut to the edge back of an outer peripheral edge 4, the portion shown by a virtual line is the portion of the outer peripheral edge 4' deleted by the cut gash 2, only the portion expanded in a taper shape is deleted, a bottom edge 7'' and an outer peripheral edge 4'' are newly formed, the outer diameter size of the tip section of the edge section 2 is made the nominal diameter size.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an end mill and a method for manufacturing the same, and more particularly to an end mill in which a gash is inserted up to the back of the peripheral blade and a method for manufacturing the same.

[Prior art]

In general end mills, a gash is placed on the rake face of the bottom edge with a medium and low angle in order to improve its cutting performance in the axial direction (bottom edge cutting). Figure 5 shows
This is a partial view of the end mill as seen from the direction perpendicular to the axis of the end mill, directly facing the bottom blade 21 to show the part where the gash is inserted (the hatched part represents the side surface of the gash). Rake face 2 of blade 22
The end mill is normally inserted at a location radially inward from the bottom cutter 21. In order to show the cutting edge angle θ1 of the bottom cutter 21, FIG. FIG. 7 is a partial view of the end mill viewed from the axial direction directly facing the outer peripheral end of the bottom blade 21 to show the cutting edge angle γ of the peripheral blade 22. The blade 21 has a clearance angle β and a medium-low angle δ, while the peripheral blade 22 has a clearance angle ε and a rake angle η, and generally also has a helix angle ν. The cutting edge angle θ1 at the outer circumferential edge al of the blade 21 is considerably smaller than the cutting edge angle γ of the outer circumferential edge 22. In normal cutting with an end mill, the outer peripheral end a of the bottom blade 21
Cutting begins at , and preventing chipping in this area is an extremely important technical issue for end mills, especially for cemented carbide end mills and high-torsion end mills. As shown in FIG. 8, the conventional chipping prevention technique for this type of end mill is to insert gash to the back of the λ circumferential blade 22 so that the outer periphery extends up to line b-c in FIG. 6. The tip of the blade 22 is removed, and as a result, the new bottom blade 21' has a large cutting edge angle θ.
, to increase the rigidity of that part.

[Problem to be solved by the invention]

By the way, in the end mill in which the gash is inserted to the back of the outer circumferential cutter 22 as described above, the outer diameter of the bottom cutter 21° becomes smaller by the amount of the outer circumferential clearance angle ε. In other words, the part indicated by the imaginary line in Fig. 8 is the part of the peripheral cutting edge that has been removed by inserting this gash.If such an end mill were to be used, for example, to machine a mold, the bottom surface of the mold would be removed. A sloping surface, as if chamfered, is formed at the boundary corner of the side surface, making it impossible to obtain a right-angled corner. The present invention has been devised in view of the problems of the prior art as described above and to effectively solve these problems. Therefore, the purpose is to provide an end mill in which the surface processed by the peripheral blade and the surface processed by the bottom blade are at right angles at the boundary, even though the gash is inserted to the back of the peripheral blade. Another object of the present invention is to provide a method for manufacturing such an end mill.

[Means to solve the problem]

The end mill according to the present invention is an end mill in which gash is inserted to the back of the peripheral blade, and the outer diameter of the bottom blade is approximately equal to the nominal diameter. Here, "approximately equal" is effective in the sense that if the degree of diameter reduction is even slightly smaller than the diameter reduction phenomenon in the conventional technology, it is better than the diameter reduction phenomenon in the conventional technology. Since the technology is also roughly the same, it is not meant to include such cases. The method for manufacturing an end mill according to the present invention includes forming a primary end mill in which a tip end of a blade part is formed in a tapered shape whose diameter increases toward the tip side, and a bottom blade of the primary end mill includes: This is done by filling the gash up to the back of the outer peripheral blade. Another method of manufacturing the end mill according to the present invention is that the clearance angle is 06.
This is done by forming a first peripheral cutting edge, and filling a gash to the back side of the first peripheral cutting edge, and then forming a flank on a second peripheral cutting edge formed. Another method for manufacturing an end mill according to the present invention is performed by forming a flank in advance from the position of the virtual secondary peripheral cutting edge that is to be formed after inserting the gashe, and then inserting the gashe.

[Effect]

According to the end mill of the present invention, even though the gash is inserted to the back of the outer peripheral cutter, the surface processed by the outer peripheral cutter and the processed surface by the bottom cutter are at right angles at the boundary, and the outer periphery of the bottom cutter is The cutting edge angle at the edge can be increased.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, the following excellent effects are exhibited. In other words, since the gash is inserted to the back of the peripheral blade, the cutting edge angle at the outer peripheral edge of the bottom blade becomes large and chipping can be prevented. , the machined surface by the outer peripheral cutter and the machined surface by the bottom cutter can be made at right angles at the boundary, and is particularly suitable for cemented carbide end mills and highly twisted end mills.

【Example】

A preferred embodiment of the present invention will be described below with reference to FIGS. 1 to 4. FIG. 1 shows the first end mill before the end mill according to the present invention is formed.
Figure 2 is a schematic diagram showing the external shape of the end mill, and is shown directly facing the bottom blade from the direction perpendicular to the axis of the end mill to show the part of the gear bush inserted in the end mill according to the present invention (the hatched part represents the side surface of the gear bush). Partial view seen,
FIG. 3 is a schematic diagram showing the outer shape of an end mill according to the present invention obtained by inserting a gear bushing into the primary end mill of FIG. 1. FIG. First, as shown in FIG. 1, the primary end mill 1 is formed into a tapered shape so that the tip 3 of the blade portion 2 thereof increases in diameter toward the tip. The axial length Q of this tapered part is equal to the axial length of the part where the diameter is reduced when the gear bushing is inserted in the case of a conventional end mill, and the length also depends on the depth of the gear bushing that is inserted. Although it varies, it is generally 0.01 to the nominal diameter size.
Approximately 0.3 times is an appropriate range. Furthermore, the maximum diameter expansion dimension ΔD of the tapered portion is made equal to the maximum radial dimension of the portion removed by inserting the gear bushing, and the size of the relief angle of the peripheral cutter 4 (shown in FIG. 2) Although it varies depending on the depth of the gear bushing, the appropriate range is generally about 0.005 to 0.155 times the nominal diameter. The maximum diameter of this tapered portion is the outer diameter DI of the bottom blade 7 (shown in Fig. 2), and the diameters of other blade portions other than the tapered portion are equal to the nominal diameter. . As shown in Figure 2, the gear bushing has been inserted to the back of the peripheral blade 4, but the part shown by the phantom line in the figure is the 4° portion of the peripheral blade that has been removed by inserting the gear bushing. By removing only the tapered diameter enlarged part, a new bottom blade 7'' and outer peripheral blade 4'' are formed, and as shown in FIG. The dimensions are exactly equal to the nominal diameter dimension. Further, as shown in Fig. 4, a primary peripheral cutting edge 4° (indicated by a broken line) with a clearance angle of 0° is formed in the margin portion 8, and this primary peripheral cutting edge 4° is O degree with respect to the second peripheral edge 4'' formed after inserting the gear bushing into the bottom edge 7゛ of the end mill with a gear bush up to the back of the first peripheral edge 4 degrees.
By forming the flank 9 having the clearance angle α as described above, it is possible to obtain an end mill in which the outer diameter of the tip 3 of the blade portion 2 is exactly equal to the nominal diameter as described above. That is, since the outer diameter in the margin portion 8 is equal to the nominal diameter everywhere, by positioning the outer peripheral end of the bottom blade 7'' in this margin portion 8, the outer diameter of the bottom blade 7'' can be made equal to the nominal diameter. Become. Conversely, the position of the imaginary secondary peripheral blade 4'' is determined in advance by determining the angle and depth of the gear bushing to be inserted into the end mill having the primary peripheral blade 4', After forming the desired outer circumferential flank surface 9 from that position, by inserting the gear bushing determined above, the end mill can be made such that the outer diameter of the tip 3 of the blade 2 is exactly equal to the nominal diameter. can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the outer shape of a primary end mill before an end mill according to an embodiment of the present invention is formed, and FIG. 2 is a portion of a gear bushing inserted in an end mill according to an embodiment of the present invention. (The hatched part represents the side surface of the gear bushing.) A partial view of the end mill viewed from the direction perpendicular to the axis of the end mill facing the bottom blade. FIG. 4 is a partial view of the end mill according to an embodiment of the present invention viewed from the axial direction facing directly toward the outer circumferential end of the bottom blade; FIG. 6 is a partial view of the end mill viewed from the direction perpendicular to the axis of the end mill facing the bottom blade to show the part where the gear bushing is inserted in the prior art, and FIG. FIG. 7 is a partial view of the end mill viewed from the right angle direction facing the outer circumferential cutter near the bottom cutter in order to show the cutting edge angle of the outer circumferential cutter in the prior art. FIG. 8 is a partial view of the end mill as seen from the direction perpendicular to the axis of the end mill, directly facing the bottom blade, to show the part in which the gash is inserted in another conventional technique. DESCRIPTION OF SYMBOLS 1... Primary end mill, 2... Blade part, 3... Tip part of the blade part, 4... Peripheral blade, 4°... Primary peripheral blade, 4-... Second Next peripheral blade, 7...Bottom blade of the primary end mill, 7"...Bottom blade, 9...Flank surface of the peripheral blade, D,
... Outer diameter dimension of bottom blade Patent Applicant Kobe Steel Co., Ltd. Representative Patent attorney Aohaku Ao (and 2 others) Figure 1
Figure 2 Figure 3 Figure 8rg Figure 7

Claims (4)

[Claims] (1) An end mill with gash inserted to the back of the peripheral blades (4, 4'), characterized in that the outer diameter dimension (D_2) of the bottom blade (7'') is approximately equal to the nominal diameter. end mill. (2) A primary end mill (1) is formed in which the tip end (3) of the blade portion (2) is tapered in diameter toward the tip side; 2. A method for manufacturing an end mill according to claim 1, characterized in that gash is inserted into the bottom blade (7) of the blade up to the back side of the peripheral blade (4). (3) A secondary outer periphery is formed after forming a primary peripheral cutting edge (4') with a relief angle of 0° and filling gash to the back of the primary peripheral cutting edge (4'). 2. A method for manufacturing an end mill according to claim 1, characterized in that a clearance surface (9) is formed on the blade (4''). (4) A claim characterized in that a flank (9) is formed in advance from the position of the virtual secondary peripheral edge (4'') to be formed after the gash is inserted, and then the gash is inserted. Item 1. A method for manufacturing an end mill according to item 1.