JP2006088278A - End mill for machining rib groove - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an end mill for machining a rib groove capable of forming a bottom part of the rib groove into a relatively flat shape while securing prevention of the occurrence of chipping and improvement of cutting efficiency. <P>SOLUTION: The end mill 1 for machining a rib groove has the following constitution. An end cutting edge 6 is formed into an arcuate shape. The radius R1 of the arcuate shape is set within the range of exceeding nearly 1.5 times of the outer diameter D and not exceeding nearly 6 times of the same. Thus, the improvement of the cutting efficiency can be realized without the occurrence of curvature of a machining face. A corner part 7 is formed into an arcuate shape. The radius R2 of the arcuate shape is set within the range of at least nearly 0.05 times of the outer diameter D and at most nearly 0.03 times of the same. Consequently, the service lifetime of the end mill 1 for machining a rib groove can be extended by solving a problem on design and by preventing the occurrence of the chipping. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an end mill for rib groove processing, and more particularly to an end mill for rib groove processing capable of forming a bottom portion of a rib groove relatively flat while preventing chipping and improving cutting efficiency. .

  Generally, the bottom blade formed at the bottom of the end mill is configured in a flat shape formed substantially perpendicular to the axis. However, such an end mill has a drawback that the cutting efficiency is poor because the contact surface between the workpiece and the bottom blade is substantially flat.

In order to eliminate such poor cutting efficiency, Japanese Patent Application Laid-Open No. 11-156620 (Patent Document 1) discloses that a cutting edge (bottom edge) is formed in a convex shape from the shank to the tip, and the circle A technique is disclosed in which the arc radius of the arcuate cutting edge (bottom edge) is configured to be 0.6 to 1.5 times the end mill diameter. According to this technology, since the cutting edge (bottom edge) is formed in an arc shape, the contact area between the workpiece and the cutting edge (bottom edge) is compared with the contact area when using a flat end mill. And can be enlarged. Thereby, the improvement of cutting efficiency can be aimed at.
Japanese Patent Laid-Open No. 11-156620 (FIG. 2)

  By the way, in the end mill for rib groove processing used for the processing of the rib groove, there is a problem that the flat bottom blade is easily chipped by chipping. On the other hand, as described above, if the arc radius of the bottom blade is configured in the range of 0.6 to 1.5 times the diameter of the end mill, it is effective for suppressing chipping. Therefore, there is a problem in that the processing surface corresponding to the above is curved, and the design requirement of forming the bottom of the rib groove flat cannot be satisfied.

  The present invention has been made to solve the above-described problems, and is intended for rib groove processing capable of forming the bottom of the rib groove relatively flat while preventing chipping and improving cutting efficiency. The purpose is to provide an end mill.

  In order to achieve this object, an end mill for rib groove processing according to claim 1 includes a tool body rotated about an axis, an oil groove recessed in an outer peripheral surface portion of the tool body, and an oil groove formed on the oil groove. An outer peripheral blade formed along the outer periphery of the tool body and a bottom blade formed on the bottom of the tool body, the outer peripheral blade being formed along the outer peripheral blade. The bottom blade is formed in an arc shape, and the arc radius is configured to be within a range of approximately 1.5 times the minimum diameter of the outer peripheral blade and approximately 6 times or less. The corner portion where the bottom blade and the outer peripheral blade intersect is formed in an arc shape, and the arc radius is within a range of approximately 0.05 times or more and approximately 0.3 times or less of the minimum diameter of the outer peripheral blade. It is configured.

  According to the rib groove processing end mill according to claim 1, the bottom blade is formed in an arc shape, and the arc radius thereof is within a range of approximately 1.5 times the minimum diameter of the outer peripheral blade and approximately 6 times or less. It consists of The bottom blade has a substantially semicircular shape as its arc radius decreases. As a result, the processed surface is curved, which causes a design problem. However, in the present invention, the arc radius of the bottom blade is configured to exceed about 1.5 times the minimum diameter of the outer peripheral blade, so that the machining surface can be formed relatively flat and the design problem can be solved. There is an effect that can be done.

  On the other hand, the bottom blade has a substantially linear shape as the arc radius increases. Thereby, the contact area of a bottom blade and a to-be-processed object becomes small, and cutting efficiency deteriorates. However, in the present invention, since the arc radius of the bottom blade is configured to be approximately six times or less the minimum diameter of the outer peripheral blade, it is possible to secure a contact area between the bottom blade and the workpiece and obtain a sufficient cutting efficiency. There is an effect that can be done.

  Further, the corner portion where the bottom blade and the outer peripheral blade intersect is formed in an arc shape, and the arc radius is configured within a range of approximately 0.05 times or more and approximately 0.3 times or less of the minimum diameter of the outer peripheral blade. ing. The corner portion has a substantially R shape as the arc radius increases. As a result, the edge of the processed groove becomes substantially R-shaped, causing a design problem. However, in the present invention, since the arc radius of the corner portion is configured to be approximately 0.05 times or more than the minimum diameter of the outer peripheral blade, the edge of the machining groove is made substantially L-shaped to solve the design problem. There is an effect that can be.

  On the other hand, the corner portion becomes sharper as its arc radius becomes smaller. Thereby, chipping is likely to occur, and the life of the end mill for rib groove processing is shortened. However, in the present invention, since the arc radius of the corner portion is configured to be approximately 0.3 times or less the minimum diameter of the outer peripheral blade, it is possible to prevent chipping and increase the life of the end mill for rib groove processing. There is an effect.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a front view of a rib groove machining end mill (hereinafter abbreviated as “end mill”) 1. FIG. 2 is an enlarged view of the end side (right side of FIG. 1) of the end mill 1. It is the side view of the end mill 1 seen from the arrow III direction. First, the overall configuration of the end mill 1 will be described with reference to FIGS. 1 to 3.

  The end mill 1 has a shank portion 2 formed in a substantially cylindrical shape, a tool body 3 disposed on the tip side (right side in FIG. 1) of the shank portion 2, and an outer peripheral surface portion of the tool body 3. An oil groove 4, an outer peripheral blade 5 provided along the oil groove 4, and a bottom blade 6 provided on the bottom portion (right side in FIG. 1) connected to the outer peripheral blade 5 and mainly formed. This is an end mill that is configured to process a rib groove by reciprocating a die that is a workpiece.

  The end mill 1 is attached to a processing machine such as a machining center via a holder (not shown) that holds the shank portion 2 and is moved while being driven to rotate about the axis O, thereby cutting the rib groove. Do.

  The tool body 3 is made of a cemented carbide obtained by pressure-sintering tungsten carbide (WC) or the like, and as shown in FIG. 1, an oil groove 4, an outer blade 5, and a bottom are formed on the outer peripheral surface portion. Blades 6 and the like are respectively formed. The material of the tool body 3 is not limited to cemented carbide, and may be composed of high speed tool steel.

  The oil groove 4 is a groove for enhancing the lubrication effect in the process of forming the rib groove, and is recessed spirally around the axis O of the tool body 3 as shown in FIG. The cutting oil is supplied to the cutting surface through the oil groove 4. In this embodiment, the twist angle is approximately 25 °. However, it is naturally possible to appropriately change this value according to the cutting conditions.

  The outer peripheral blade 5 is formed along the oil groove 4 and is formed in a tapered shape whose diameter is reduced toward the distal end direction (right direction in FIG. 1) of the tool body 3.

  As shown in FIG. 2, the bottom blade 6 is connected to the outer peripheral blade 5, and has a convex arc shape from the shank portion 2 toward the bottom of the tool body 3 (upward in FIG. 2) at the bottom of the tool body 3. Is formed. Further, as shown in FIG. 3, a pair of bottom blades 6 are formed symmetrically with respect to the axis O.

  The corner portion 7 where the outer peripheral blade 5 and the bottom blade 6 intersect is formed in an arc shape as shown in FIG.

  Next, referring to FIG. 4, the taper angle α of the outer peripheral blade 5 (see FIG. 2), the arc radius R1 of the bottom blade 6 (see FIG. 2), and the arc radius R2 of the corner portion 7 (see FIG. 2). explain. FIG. 4 is a cross-sectional view schematically showing a rotation locus of the rib groove machining end mill 1 for machining the rib groove. In order to facilitate understanding, the taper angle α and the arc radius R2 are shown larger than actual.

  Here, the rotation locus 15 is the rotation locus of the outer peripheral blade 5, the rotation locus 16 is the rotation locus of the bottom blade 6, and the rotation locus 17 is the rotation locus of the corner portion 7. Further, the outer diameter D is a distance connecting the intersection of the extension line of the rotation locus 15 and the tangent at the axis O of the rotation locus 16 as shown in FIG.

  In this embodiment, the outer diameter D is D = 1.0 mm. The outer diameter D is preferably 6.0 mm or less. This is because by applying the present invention to the end mill 1 having an outer diameter D of 6.0 mm or less, the effects of the present invention can be more remarkably exhibited. Specifically, in the case of a relatively large diameter end mill having an outer diameter D of 6.0 mm or more, even if the arc radius R2 is increased in order to prevent chipping, there is little influence on the design. The “minimum diameter of the outer peripheral blade” recited in claim 1 refers to the outer diameter D.

  As shown in FIG. 4, the taper angle α is an angle formed by the rotation locus 15 and a straight line parallel to the axis O, and is 30 ′ in this embodiment. However, it is naturally possible to appropriately change this value according to the cutting conditions.

  As shown in FIG. 4, the arc radius R1 is the arc radius of the rotation locus 16 configured in a convex arc shape toward the upper side (upper side in FIG. 4), and the arc radius R1 is the tool main body 3 (see FIG. 4). 2)) and the outer diameter D of the bottom side (upper side of FIG. 4) is more than 1.5 times and less than 6 times. In the present embodiment, the arc radius R1 is R1 = 5D.

  Here, the reason why the arc radius R1 is set to a value exceeding about 1.5 times the outer diameter D is as follows. That is, the bottom blade 6 has a substantially semicircular shape as the arc radius R1 decreases. As a result, the processed surface is curved, which causes a design problem. Therefore, by setting the arc radius R1 to a value exceeding about 1.5 times the outer diameter D, the processed surface can be formed relatively flat, and the design problem can be solved.

  On the other hand, the reason why the arc radius R1 is set to a value of about 6 times or less of the outer diameter D is as follows. That is, the bottom blade 6 has a substantially linear shape as the arc radius R1 increases. Thereby, the contact area between the bottom blade 6 and the workpiece is reduced, and the cutting efficiency is deteriorated. Therefore, by setting the arc radius R1 to a value that is approximately 6 times or less of the outer diameter D, a contact area between the bottom blade 6 and the workpiece can be secured, and sufficient cutting efficiency can be obtained.

  As shown in FIG. 4, the arc radius R2 of the corner portion 7 is the arc radius of the rotation locus 17, and the arc radius R2 is approximately 0.05 times or more and approximately 0.3 times or less of the outer diameter D. Configured within range.

  The reason why the arc radius R2 is set to a value approximately 0.05 times or more the outer diameter D is as follows. That is, the corner portion 7 has a substantially R shape as the arc radius R2 increases. As a result, the edge of the groove to be processed becomes substantially R-shaped, which causes a design problem. Therefore, by setting the arc radius R2 to a value that is approximately 0.05 times or more the outer diameter D, the edge of the processed rib groove can be formed at a relatively right angle, and the design problem can be solved. .

  On the other hand, the reason why the arc radius R2 is set to approximately 0.3 times or less of the outer diameter D is as follows. That is, the corner portion 7 becomes sharper as the arc radius R2 becomes smaller. Thereby, chipping is likely to occur, and the life of the end mill 1 is shortened. Therefore, by setting the arc radius R2 to a value approximately 0.3 times or less of the outer diameter D, chipping can be prevented and the life of the end mill 1 can be increased.

  Next, with reference to FIG. 5, the cutting test performed using the end mill 1 comprised as mentioned above is demonstrated.

  The cutting test is a test for measuring the durability of the end mill 1 by reciprocating linearly moving the end mill 1 under a predetermined condition to process a rib groove on the workpiece. The durability is determined based on the number of processed grooves processed until the end mill 1 is damaged such as chipping.

  Detailed specifications of the cutting test are: Work material: S50C, Cutting method: Reciprocating cutting, Cutting oil: Water-insoluble cutting oil, Cutting speed: 47 m / min, Feeding speed: 675 mm / min, Axial cut: 0.02 mm It is. For the cutting test, an end mill 1 having an outer diameter D of 1.0 mm and a blade length of 12 mm was used.

  The dimension of the rib groove to be processed is such that the groove length in the feeding direction of the end mill 1 is 100 mm and the groove depth in the cutting direction is 10 mm (corresponding to 250 reciprocations). Further, the groove width in the direction perpendicular to the feed direction corresponds to the rotation locus of the outer peripheral blade 5. The number of processed grooves to be described later (see FIG. 5) is calculated with the rib groove having this dimension as one unit.

  FIG. 5 is a diagram showing the results of the cutting test, and shows the relationship between the arc radius R1 and arc radius R2 (see FIG. 4) and the durability of the test tool. In FIG. 5, the “No.” column indicates the measurement No. It shows that measurement was performed on 14 types of cutting conditions.

  The “R1” column and the “R2” column indicate the values of the arc radius R1 and the arc radius R2, respectively. Note that “-” in this column means that the arc radius is zero.

  In addition, the “number of processed grooves” column indicates the number of processed rib grooves that could be processed without breaking the test tool under a predetermined cutting condition. For easy understanding, a bar graph and a numerical value are shown. It was expressed using

  As shown in FIG. 9, no. 11 and no. In No. 13, chipping occurred in the end mill 1 with a relatively small number of processed grooves. This seems to be because the strength of the corner portion 7 (see FIG. 3) could not be ensured because the value of the arc radius R2 is configured to be smaller than about 0.05D.

  No. 2 and No. 5 to No. At 8, the value of the number of processed grooves is relatively large although the value of the arc radius R2 is 0. This is because the value of the arc radius R1 is configured to be 6D or less, that is, the bottom blade 6 (see FIG. 3) is formed in a relatively convex arc shape. This is probably because the angle at which the corners intersect can be increased and the strength of the corner portion 7 can be ensured.

  No. 10 and no. 12, the value of the number of machining grooves is notwithstanding that the value of the arc radius R1 exceeds 6D and the bottom blade 6 approaches a straight line (that is, the angle at which the bottom blade 6 and the outer peripheral blade 5 cross each other becomes small). Is relatively large. This is because the strength of the corner portion 7 is secured by greatly expanding the value of the arc radius R2. However, in this case, R at the edge of the machining groove becomes too large to satisfy the design requirement.

  On the other hand, no. 1, no. 3 and no. In No. 4, the number of processed grooves was large, and good results were obtained. This is because the value of the arc radius R2 is configured to be approximately 0.05D or more and the value of the arc radius R1 is configured to be approximately 6D or less, thereby improving the strength of the corner portion 7 and preventing chipping. At the same time, it seems that the cutting efficiency can be improved by making the shape of the bottom blade 6 a relatively convex arc shape.

  In addition, these No. 1, no. 3 and no. 4, the value of the arc radius R2 is configured to be approximately 0.3D or less, and the value of the arc radius R1 is configured to exceed approximately 1.5D, so that the bottom of the rib groove is formed flat. The design requirements are satisfied at the same time.

  From the above results, the value of the arc radius R1 exceeds about 1.5D and is within the range of about 6D or less, and the value of the arc radius R2 is about 0.05D or more and about 0.3D or less. By being configured within the range, the end mill 1 (see FIG. 1) can be effectively prevented from being broken and chipped, the end mill 1 can have a long life, and the design requirements can also be satisfied. Can do.

  The present invention has been described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various improvements and modifications can be easily made without departing from the spirit of the present invention. It can be guessed.

  For example, in the above-described embodiment, the case where the end mill 1 is configured with two blades has been described. However, the present invention is not necessarily limited thereto. For example, the end mill 1 may be configured with three or more blades. .

It is a front view of the end mill for rib groove processing. It is an enlarged view of the front end side of the end mill for rib groove processing. It is a side view of the end mill for rib groove processing seen from the arrow III direction of FIG. It is sectional drawing which shows typically the rotation locus | trajectory of the end mill for rib groove processing. It is the figure which showed the result of the cutting test.

Explanation of symbols

1 End mill for rib groove processing 3 Tool body 4 Oil groove 5 Outer peripheral blade 6 Bottom blade 7 Corner portion D Outer diameter (minimum diameter)
R1 Arc radius R2 Arc radius

Claims (1)

A tool main body rotated about an axis, an oil groove recessed in an outer peripheral surface portion of the tool main body, and an outer peripheral blade formed along the oil groove and having a tapered taper in the rotation trajectory And a rib groove machining end mill used for machining a rib groove, comprising a bottom blade provided on the outer peripheral blade and formed at the bottom of the tool body.
The bottom blade is formed in an arc shape, and the arc radius is configured to be within a range of approximately 1.5 times the minimum diameter of the outer peripheral blade and approximately 6 times or less.
The corner portion where the bottom blade and the outer peripheral blade intersect is formed in an arc shape, and the arc radius is within a range of about 0.05 times or more and about 0.3 times or less the minimum diameter of the outer peripheral blade. An end mill for rib groove processing, characterized in that it is configured.

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