JP2008036722A - Radius end mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform grinding processing at much higher processing efficiency by improving chip discharging performance to suppress chip jamming in a radius end mill for rough processing with a lager number of cutting blades than normal. <P>SOLUTION: In this radius end mill, a corner round blade 16 and a bottom blade 18 are smoothly connected with each other, and directed outward so that an eccentric angle θ of a tangent P at a connection point Q of the blades becomes 5° or larger. Because the bottom blade 18 has an extended dimension X of 1/10 or larger of a radius R of the corner round blade 16, the chips cut by the bottom blade 18 and the corner round blade 16 are sufficiently discharged to an outer peripheral side accompanied by the rotation of a tool. Thereby, even in this radius end mill 10 for rough processing with a lager number of cutting blades 12 and a smaller chip pocket than normal, chip discharging performance is improved to suppress chip jamming. Also, cut processing can be performed at much higher processing efficiency. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radius end mill, and more particularly, to an improvement in a radius end mill for rough machining in which the number of cutting edges is larger than usual.

A cutting edge having a 1/4 arc-shaped corner radius blade provided at the outer peripheral corner portion of the tool tip and a bottom blade continuously provided on the corner radius blade and extending toward the axial center is formed around the axis. A plurality of radius end mills are known. The end mills described in Patent Documents 1 and 2 are an example, and such a radius end mill is suitably used for three-dimensional curved surface processing of a mold.
JP 2004-50338 A JP 2003-71626 A

  By the way, the radius end mill for rough machining that performs high-efficiency machining has a larger number of blades than a normal one, and has, for example, about 4 to 6 cutting edges in the case of a φ10 end mill. This is because it is possible to increase the feed rate and the amount of cutting as much as the number of cutting edges increases without increasing the amount of cutting per cutting edge, so that the machining efficiency can be improved accordingly. It becomes.

  However, when the number of cutting edges is increased in this way, the chip pocket volume per cutting edge is reduced, so that chip clogging is likely to occur, and a sufficient processing efficiency improvement effect cannot always be obtained. there were. In other words, the bottom edge is also involved in the cutting process due to elastic deformation of the work material, but the conventional bottom edge is formed by gashing using a grindstone different from the grinding wheel that grinds the corner radius blade. Since it extends straight from the connection point with the round blade toward the axis, the action of pushing out the chips toward the outer peripheral side is weak, and chip clogging tends to occur at the bottom blade portion. Even in the corner radius blade portion, the action of pushing out the chips to the outer peripheral side is weak like the bottom blade. In particular, the larger the radius of the corner radius blade and the larger the discharge amount of the chips, the more likely the chip clogging occurs. In addition, when performing grooving or the like on a work material having a relatively low hardness (for example, about 40 HRC or less), the cutting amount per cutting edge can be increased, but the cutting amount is the amount of chip discharge, Chip clogging is likely to occur as the cutting amount is increased.

  The present invention has been made against the background of the above circumstances, and the object of the present invention is to improve chip discharge performance and reduce chip clogging in a radius end mill capable of high-efficiency machining with more cutting edges than usual. By suppressing, it exists in enabling it to cut with still higher processing efficiency.

  In order to achieve such an object, according to the first aspect of the present invention, a 1/4 arc-shaped corner radius blade provided at an outer peripheral corner portion at the tip of the tool, and the corner radius blade is provided continuously to the axis S side. In a radius end mill having a plurality of cutting edges each having a bottom edge extending around the axis S, (a) when viewed from the bottom in the axial direction, the bottom edge is opposite to the corner edge. (B) The tangent line P at the connection point Q between the corner radius blade and the bottom blade is cut off with respect to the straight line L connecting the connection point Q and the axis S. (C) An extension dimension X in the straight line L direction of the bottom blade smoothly extending from the connecting point Q is inclined to the corner so that the eccentric angle θ is inclined so as to be outward. It is characterized by being 1/10 or more of the radius R of the radius blade To do.

  According to a second aspect of the present invention, in the radius end mill of the first aspect, the bottom blade has a convex arc shape that is smoothly connected to the corner radius blade in the bottom view, and grinding that corner radius blade is ground. It is provided by grinding using the grindstone continuously to the grinding of the corner radius blade.

  According to a third aspect of the present invention, in the radius end mill of the first or second aspect, the eccentric angle θ is in the range of 10 ° to 40 °, and the extension dimension X is R / 5 or more.

  According to a fourth aspect of the present invention, in the radius end mill according to any one of the first to third aspects of the present invention, the radius end mill is provided for roughing processing having four or more cutting edges around the axis.

  In such a radius end mill, the corner blade and the bottom blade are smoothly connected as viewed from the bottom in the axial direction, and the eccentric angle θ of the tangent line P at these connection points Q is 5 Since the bottom blade has an extended dimension X that is 1/10 or more of the radius R of the corner radius blade, the chips cut by the bottom blade or the corner radius blade Is discharged to the outer peripheral side with the rotation of the tool. As a result, even in a radius end mill for rough machining with a larger number of cutting edges and smaller chip pockets than usual, chip discharge performance is improved, chip clogging is suppressed, and cutting is performed with higher machining efficiency. Will be able to.

  In the second invention, since the bottom edge is ground continuously after the cornering edge grinding using the grinding wheel for grinding the cornering edge, the radius end mill of the present invention is as simple and inexpensive as the conventional one. Can be manufactured.

  In the third invention, since the eccentric angle θ is 10 ° or more and the extension dimension X is R / 5 or more, the chip discharging performance is further improved. Further, since the eccentric angle θ is 40 ° or less, the predetermined extension dimension X can be ensured while avoiding interference with the adjacent cutting edge.

  The radius end mill of the fourth invention is for rough machining having a large number of four or more cutting edges, and can increase the feed speed and the amount of cutting by the number of cutting edges, and can be turned outward. The machining efficiency can be improved in combination with the improvement of the chip discharge performance by the bottom blade of.

  The radius end mill of the present invention is used for cutting various work materials, and the processing conditions are appropriately set according to the material of the work material, for example, relatively low hardness (for example, about 40 HRC or less) When grooving, etc., on a workpiece, it is suitably used when cutting under high-efficiency machining conditions such as high-speed feed or important amount of cutting that increases the cutting amount per cutting edge. The

  As the radius R of the corner radius blade is larger, the amount of chips discharged by the corner radius blade is increased, and chip clogging is likely to occur. Therefore, the present invention provides a radius end mill having a relatively large radius R. For example, it is suitably applied when the radius R is about 1.5 to 2 mm or more, or the radius R is 15% to 20% or more of the tool diameter D.

  When the eccentric angle θ of the tangent line P of the cutting edge at the connection point Q is smaller than 5 °, or when the extension dimension X of the bottom blade is smaller than 1/10 of the radius R of the corner radius blade, the cutting edge is made outward. Therefore, it is necessary to set the eccentric angle θ to 5 ° or more and the extension dimension X to R / 10 or more. However, as in the third invention, the eccentric angle θ Is preferably in the range of 10 ° to 40 °, and the extension dimension X is preferably R / 5 or more.

  The aspect in which the bottom blade is smoothly connected to the corner radius blade in the bottom view is, for example, when the bottom blade and the corner radius blade are connected at an intermediate position of a curve such as a smooth curved arc or a straight line. In addition, the corner blade may be a curved curve, and the bottom blade may extend linearly in the tangential direction of the curve at the connection point.

  In the second invention, the bottom blade is ground using a grinding wheel that grinds the corner radius blade. However, in implementing the other inventions, a grinding wheel for gashes different from the grinding wheel for the corner radius blade is used. Various processing methods can be employed, such as forming a bottom blade that is smoothly connected to the corner radius blade by grinding the gasche. Further, the shape of the bottom blade does not necessarily need to be a convex arc shape in the bottom view, and various forms are possible such as a shape that extends linearly from the connection point Q with the corner radius blade in the bottom view. In addition to the portion that smoothly extends from the corner radius blade (in the range of the extension dimension X), it is also possible to provide a central blade on the axis S side of the bottom blade by gash processing.

  The present invention is preferably applied to a radius end mill for rough machining having a large number of four or more cutting edges as in the fourth invention, but can also be applied to a radius end mill having three or fewer blades. In addition, the cutting edge is not necessarily limited to rough machining, and the cutting edge is used when the number of cutting edges is larger than usual and cutting can be performed under high-efficiency machining conditions such as high-speed feed or precious amount. It has a technical significance in suppressing chip pockets from becoming smaller and chip clogging is likely to occur, and can be applied to a radius end mill other than for roughing.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a view showing a radius end mill 10 according to an embodiment of the present invention, where (a) is a bottom view seen from the front end side in the axial direction, and (b) is a rotational locus shape of one cutting edge 12. FIG. The radius end mill 10 has a tool diameter D of 10 mm, but has four cutting edges 12 which are larger than usual, and is provided around the axis S at equal angular intervals. Each of the cutting edges 12 has the same shape, and includes a peripheral cutting edge 14, a corner cutting edge 16, a bottom cutting edge 18, and a central cutting edge 20 that are parallel to the axis S in the shape of the rotation locus (b).

  The outer peripheral cutting edge 14 is provided along the torsion groove 22 formed by grinding with a grinding wheel on the outer peripheral surface of the tool. The radius end mill 10 of the present embodiment performs cutting by being driven to rotate counterclockwise about the axis S in the bottom view of FIG. 1 (a). Chips are discharged to the shank side in the twist groove 22. It is provided with a right twist. The corner radius blade 16 is a portion that is provided at the outer peripheral corner portion at the tip of the tool and smoothly connects the outer peripheral cutting edge 14 and the bottom blade 18, and is 1/4 of a predetermined radius R in the rotational trajectory shape of FIG. In this embodiment, it is provided along the twisted groove 22 with a radius R = 2 mm, that is, 20% of the tool diameter D. The bottom blade 18 is a portion that is smoothly connected to the corner blade 16 and extends toward the axis S, and has a convex arc shape in the bottom view of FIG. It is provided along. That is, the outer peripheral cutting edge 14, the corner radius blade 16, and the bottom edge 18 are provided along the twist groove 22 by forming the twist groove 22 by grinding using a common grinding wheel. Therefore, the bottom blade 18 is formed by cutting the grinding wheel from the corner radius blade 16 portion to the axis S side at a predetermined twist angle.

  Further, the center blade 20 uses a gash grinding wheel different from the above-mentioned grinding wheel to grind the tip gash 24 so as to intersect the bottom blade 18 in the vicinity of the axis S, whereby the center blade 20 shown in FIG. It is provided so as to be bent with respect to the bottom blade 18 in the bottom view. The center blade 20 and the bottom blade 18 are provided so as to be recessed toward the axis S at a predetermined center recess angle α, as is apparent from the rotational locus shape of FIG. The intermediate concave angle α is suitably in the range of 1 ° to 15 °, for example, and is set in the range of 2 ° to 5 ° in this embodiment.

  Here, the corner blade 16 and the bottom blade 18 are inclined so as to face outward with respect to a straight line L connecting the connection point Q and the axis S in the bottom view of FIG. In addition, a continuous convex arc shape including the connection point Q is formed. The corner radius blade 16 and the bottom blade 18 are provided so that the eccentric angle θ at which the tangent line P at the connection point Q is inclined outward with respect to the straight line L is 5 ° or more. The eccentric angle θ is in the range of 10 ° to 40 °. The extension dimension X of the bottom blade 18 extending smoothly from the connection point Q in the straight line L direction is 1/10 or more of the radius R of the corner radius blade 16, and in this embodiment, R / 5 or more, that is, 2 mm ÷. 5 = 0.4 mm or more.

  In the radius end mill 10 of this embodiment, the corner blade 16 and the bottom blade 18 are smoothly connected in the bottom view of FIG. 1 (a), and the tangent line P is eccentric at the connection point Q. Further, the bottom blade 18 has an extended dimension X that is 1/10 or more of the radius R of the corner radius blade 16, so that the angle θ is 5 ° or more. Chips cut by the round blade 16 are favorably discharged to the outer peripheral side as the tool rotates. As a result, even in the radius end mill 10 for rough machining, which has a larger number of cutting edges 12 and smaller chip pockets than a normal one, chip discharge performance is improved and chip clogging is suppressed, and cutting is performed with higher machining efficiency. Will be able to do. That is, the radius end mill 10 of the present embodiment is for rough machining, and has four cutting edges 12 more than usual, so that the cutting edge 12 of the cutting edge 12 can be increased without increasing the cutting amount per cutting edge. The feed rate and the depth of cut can be increased by the larger number, and the machining efficiency can be improved in combination with the improvement of chip discharge performance.

  Further, in this embodiment, since the bottom edge 18 is ground continuously after the grinding of the outer corner cutting edge 14 and the corner radius edge 16, the bottom edge 18 is ground continuously. Similarly, it can be manufactured easily and inexpensively.

  In this embodiment, since the eccentric angle θ is 10 ° or more and the extension dimension X is R / 5 or more, the chip discharging performance is further improved. On the other hand, the eccentric angle θ is 40 ° or less. The predetermined extension dimension X can be secured while avoiding interference with the blade 12.

FIG. 2 is a diagram for explaining the results of examining the machining efficiency (cutting amount) at which grooves can be cut using the product of the present invention and the comparative product, and cutting can be performed without causing chip clogging. (A) in FIG. 2 shows the test conditions, the tool diameter of the test product D = 10 mm, the radius R of the corner radius R = 2 mm, the processing length of the groove 350 mm, the work material is S50C, the cutting oil is air blow, The peripheral speed is 100 m / min, the feed speed is 3.2 m / min, and the machine used is a vertical machining center. As shown in FIG. 2 (b), for two types of radius end mills having four and six cutting edges, a total of 11 test pieces (No1 to No. 1) having different eccentric angles θ and extension dimensions X were used. No. 11) was prepared, and the cutting amount a _a that could be cut without causing chip clogging was examined, and compared with the cutting ratio (a _a / R) divided by the radius R (= 2 mm) of the corner radius blade. That is, a value obtained by multiplying the cutting ratio (a _a / R) by the radius R (= 2 mm) is the cutting amount a _a . However, for specimen No. 2, the abnormal noise became louder when grooving at the cutting rate (a _a /R)=0.3, and was interrupted halfway regardless of chip clogging, so the cutting rate (a _a / R) = 0.25, but the practically possible cutting rate (a _a / R) is 0.2. Note that test products Nos. 1, 2, and 7 having an eccentric angle θ of 0 ° or an extension dimension X of 0 mm are comparative products, and the other products are products of the present invention.

As is apparent from the test results in FIG. 2 (b), the test products No. 3 to 6 and 8 to 11 according to the present invention are compared with the test products No. 1, 2, and 7 in comparison with the cut amount a _a or the cut. Groove processing can be performed at a high efficiency in which the ratio (a _a / R) is twice or more. In particular, the specimens Nos. 4, 6, and 9 to 11 having an eccentric angle θ of 10 ° or more and an extension dimension X of R / 5 (= 0.4 mm) or more have a cutting ratio (a _a /R)=0.6. High-efficiency machining with _a cutting depth a _a of 0.6 × 2 = 1.2 mm is possible.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention implements in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining an example at the time of applying this invention to the radius end mill for roughing of 4 blades, (a) is a bottom view seen from the front end side of an axial direction, (b) is the rotation locus | trajectory shape of a cutting edge FIG. It is a figure explaining the result of investigating the processing efficiency (cutting ratio) that was able to perform grooving without causing chip clogging using multiple test products, (a) is the test condition, (b) is the test result It is.

Explanation of symbols

  10: Radius end mill for rough machining 12: Cutting edge 16: Corner radius blade 18: Bottom edge S: Shaft center Q: Connection point P: Tangent angle θ: Eccentric angle R: Radius of corner radius X: Extension dimension

Claims (4)

A cutting edge having a 1/4 arc-shaped corner radius blade provided at an outer peripheral corner portion at the tip of the tool and a bottom blade continuously provided on the corner radius blade and extending toward the axis S side. In the radius end mill provided around S,
In the bottom view seen from the front end side in the axial direction, the bottom blade is smoothly connected to the corner blade,
The tangent line P at the connection point Q between the corner radius blade and the bottom blade has an eccentric angle θ of 5 ° or more so that the cutting edge faces outward with respect to a straight line L connecting the connection point Q and the axis S. Is inclined at
A radius end mill characterized in that an extension dimension X in the straight line L direction of the bottom blade extending smoothly from the connection point Q is 1/10 or more of a radius R of the corner radius blade. The bottom blade has a convex arc shape smoothly connected to the corner radius blade in the bottom view, and is continuous with the grinding of the corner radius blade using a grinding wheel for grinding the corner radius blade. The radius end mill according to claim 1, wherein the radius end mill is provided by being ground. 3. The radius end mill according to claim 1, wherein the eccentric angle θ is in a range of 10 ° to 40 °, and the extension dimension X is R / 5 or more. The radius end mill according to any one of claims 1 to 3, wherein the radius end mill is for roughing processing in which four or more cutting edges are provided around an axis.

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