JP2008056542A - Rotary cutting tool for processing glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary cutting tool with which a groove width can be stably obtained by suppressing the wear of the tool in cutting of a groove of glass to be cut. <P>SOLUTION: The rotary cutting tool has a semi-spherical surface at the tip end part of a columnar tool main body. In the semi-spherical surface, a plurality of grooves extending toward the rear end from the vicinity of the rotary center of the tool are provided, and the ratio of the semi-spherical surface to the groove is set to be 1/0.5 to 1/2.5 at around R45° of the semi-spherical surface. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rotary cutting tool for machining a groove in glass.

As a method of cutting a groove in glass, there is a method in which a rotation center axis of a ball end mill or a square end mill is inclined with respect to the processing surface and sent parallel to the processing surface (see Patent Document 1). Some of them cut a groove with a depth of 1 μm or more at a portion where the cutting speed is higher than the cutting edge near the shaft.
JP 2005-96399 A

However, in the end mill described in Patent Document 1, brittle materials such as glass are very hard, and the tool rotation trajectory tends to be reduced (hereinafter referred to as abrasion) due to damage to the cutting edge, which is desirable during grooving. The groove width could not be obtained stably. In particular, the square end mill has a corner portion in which the rotation trajectory formed by the bottom blade and the outer peripheral blade forms a substantially right angle, and therefore wear easily proceeds, and is not suitable for stably obtaining a desired groove depth.
The present invention has been made based on the background as described above, and it is possible to obtain a stable groove width over a long period of time by suppressing wear of a tool while suppressing damage to glass as a work material. An object is to provide a tool that can be used.

  The present invention is a rotary cutting tool having a hemispherical surface at the tip of a cylindrical tool body, the hemispherical surface is provided with a plurality of grooves extending from the vicinity of the tool rotation center toward the rear end, and The ratio of the hemispherical surface to the groove is set to 1: 0.5 to 2.5 in the vicinity of R45 degrees of the hemispherical surface. Thereby, even if the ridge formed by the hemispherical surface and the wall surface of the groove is damaged, wear of the tool can be suppressed, and a desired groove width can be obtained over a long time. Further, in the present invention, the plurality of grooves are preferably provided from the position of R10 degrees toward the rear end, and the grooves are provided to a position close to the tool front end, which can cope with machining using the tool front end side. Further, the hemispherical portion is covered with a hard film, and the hardness of the hard film is preferably HV30 GPa or more, and the rotation trajectory can be maintained for a longer time by suppressing wear of the hemispherical surface.

  As described above, according to the present invention, it is possible to provide a rotary cutting tool capable of stably obtaining a groove width by suppressing wear of a tool in cutting a glass groove as a work material.

  Hereinafter, the present invention will be described with reference to the drawings. As shown in FIG. 1, the tool of the present invention has a hemispherical surface 2 at one end of a tool body 1. As shown in FIGS. 2 and 3, the most distal end portion 3 of the hemispherical surface 2 that protrudes to the most distal end side of the tool is located on the rotation center of the tool. A plurality of grooves 4 are provided radially around the most distal end portion 3 of the hemispherical surface 2, and the hemispherical surface 2 is provided in a band shape from the tool center side to the outer peripheral side. A ridge line 5 is formed by the wall surface of the groove 4 facing the tool rotation direction and the hemispherical surface 2, and the work material is cut by the ridge line 5. As shown in FIG. 4, according to the present invention, the tool rotation axis is inclined with respect to the machining surface, so that cutting can be performed without using the tool tip side having a slow cutting speed, and the groove 4 is necessarily provided to the tool tip. There is no. In the present invention, since the ratio of the hemispherical surface 2 to the groove 4 is provided in the range of 1: 0.5 to 2.5 near R45 degrees, even if the ridge line 5 is damaged, the hemisphere whose rotation diameter does not change behind it. Since the surface 2 is present, it is possible to suppress wear, which is a decrease in the radius of the rotation trajectory of the tool, and to obtain a desired groove width over a long period of time. Here, R45 degrees is a position at which a line passing through the center point of the hemisphere and forming 45 degrees with the tool rotation center axis intersects the hemisphere when viewed from the front of the tool. The ratio is the ratio of the hemispherical surface 2 and the groove 4 at the position where the line intersects the hemispherical surface as viewed from the left side of the tool. When the ratio of the hemispherical surface 2 to the groove 4 is smaller than 1: 0.5, the ratio of the hemispherical surface 2 is increased, the distance at which the hemispherical surface 2 rubs against the work material is increased, and wear tends to proceed. On the other hand, if the ratio of the hemispherical surface 2 to the groove 4 exceeds 1: 2.5, the width of the hemispherical surface 2 becomes small and wear cannot be suppressed.

  Next, this invention provided the groove | channel 4 toward the tool rear end from the position of R10 degree | times. R10 degrees is a position where a line passing through the center point of the hemisphere and forming 10 degrees with the tool rotation center axis intersects the hemisphere 2 in the tool front view as in the case of R45 degrees. Thereby, the inclination angle of the tool with respect to the machining surface at the time of machining can be increased, and the degree of machining freedom is increased. If a groove is provided from the position of R10 degrees to the tool tip side, a sufficient hemispherical width cannot be provided to the tool tip, and wear of the tool cannot be suppressed.

  Furthermore, it is preferable that the width of the hemispherical surface 2 in the tool rotation direction is increased as it goes from the tool front end side to the rear end. This is because the cutting load of the ridge line 5 varies depending on the part, and the cutting amount with respect to the one-blade feed amount increases as the distance from the tool tip portion toward the rear end side, and the tool diameter increases and the cutting speed increases. Because the load on the ridge line is large and the wear tends to progress due to heat generation, increasing the width toward the rear end suppresses wear of the tool, and the groove width can be obtained stably over a long period of time. it can.

  It is preferable that the plurality of grooves are arranged uniformly in the tool rotation direction around the tool rotation axis, thereby making it possible to make the feed amount of one edge of each ridge line 5 constant, equalize the load, and suppress wear. it can. If they are arranged unevenly, the feed amount for one blade is increased depending on the ridge line, the cut amount is increased, and it is easy to cause cracks and chipping of the work material.

  In the present invention, as shown in FIG. 4, when machining while feeding the tool in a tilted direction (left side in FIG. 4), when the tool rotates counterclockwise in the tool tip view, the ridge line 5 becomes the tool tip. It is preferable to form it so as to go in the direction of tool rotation as it goes from the rear end to the rear end, and the cutting force applied to the work material and the cutting start part of the ridge line 5 works in the direction of the work material, and chips are generated by the compression action It is possible to suppress cracking of the work material. Further, chips are discharged on the side opposite to the feed direction of the tool, and the biting of chips into the ridge line 5 can be prevented. Thereby, damage to the ridge line 5 can be suppressed, the groove width can be stably obtained, and the surface roughness of the work material can be improved.

  Moreover, it is preferable that the rake angle of the ridge line 5 is negative in a cross-sectional view perpendicular to the tool rotation center axis of the hemispherical surface 2. As a result, compressive force is generated on the work material side, and chips are generated so as to press the work material, so that cracks and chips are generated at the boundary between the groove to be machined and the surface of the work material. It can be suppressed and a beautiful processed surface can be obtained. Since glass is a brittle material, when it is processed with a sharp edge, many cracks occur on the processed surface due to the brittleness caused by the mechanical properties of the glass. Moreover, it is preferable that the tool of this invention coat | covers a hard film | membrane whose hardness is HV30GPa or more on a hemispherical surface, and can suppress wear of the hemispherical surface 5 and can suppress wear of a tool. Further, in the present invention, the number of grooves is preferably 4 or more, and by providing a large number of ridge lines 5, it is possible to increase the feed rate and perform glass groove processing with high efficiency. In the cross section orthogonal to the longitudinal direction of the groove, the groove shape may be U-shaped, V-shaped, or hemispherical. Furthermore, as illustrated in FIG. 7, a plurality of grooves extending at a wide angle from the vicinity of the tool rotation center toward the rear end may be provided. Hereinafter, specific description will be made based on examples.

(Example 1)
As Example 1 of the present invention, a cemented carbide tool is prepared, the tool diameter is set to 0.4 mm, six grooves 4 are formed in the hemispherical surface 2, and the tool tip is viewed from the tool tip as shown in FIG. From the position of R10 degrees toward the rear end of the tool, the rear end was provided at equal intervals radially from the front end of the tool. A ridge 5 is formed by the groove 4 and the hemispherical surface 2. The rake angle of the ridge line 5 was set to -10 °. The ratio of the hemispherical surface 2 and the groove 4 at the position of R45 degrees was 1: 2. As Comparative Example 2, a hemispherical surface separated by adjacent grooves and provided with relief in the rotational direction from the ridge line and with a relief angle of 10 ° was prepared with the same specifications as Example 1 of the present invention.
As a cutting test, quartz glass having a length of 70 mm, a width of 30 mm, and a thickness of 1.7 mm is used as a work material, and the rotation center axis of the tool is inclined by 45 ° with respect to the work surface of the work material as shown in FIG. The machine tool was gripped so that it could rotate. The rotation speed of the tool is 20000 min ⁻¹ , the feed rate of the blade is 6 nm, the feed rate is 0.24 mm / min, the depth of cut in the direction perpendicular to the machining surface is 0.02 mm, and the tool tilt direction (left side in FIG. 4) Send tools and process. The groove shape to be processed has a maximum groove width of 0.174 mm and a maximum depth of 0.02 mm. In the processing, the work was performed with the work material submerged in water for cooling. In this test, the processing was stopped when the groove width was less than 0.165 mm and the groove depth was less than 0.015 mm. Moreover, the maximum amount of wear of the tool for each cutting distance of 20 mm was measured.
Here, the maximum amount of wear is the radius of the rotation trajectory before machining from the hemispherical rotation trajectory before machining to the rotation trajectory after machining in the rotation trajectory formed by the cutting edge in a cross-sectional view including the rotation axis of the tool. This is the amount of reduction in the direction, and the largest portion of the wear of the rotational trajectory of the hemisphere was recorded.

  As a result, as shown in FIG. 5, a slight amount of scratches with the work material was generated on the hemispherical surface due to the feed of the tool. In addition, the maximum wear amount of the present invention example 1 is as good as 5.6 μm at the cutting length of 200 mm, and the maximum groove width is 0.168 mm and the maximum groove depth is 0.016 mm, and both the groove width and groove depth can be maintained for a long time. It was. Further, the average surface roughness Ra of the bottom surface of the groove was as good as 0.078 μm, and the groove could be provided flat. On the other hand, as shown in FIG. 6, in Comparative Example 2, the maximum abrasion amount was 10.2 μm, exceeding 7 μm, and the groove width could not be maintained after cutting 200 mm. This is thought to be because the mechanical strength of the cutting edge was insufficient because the relief was provided in the hemispherical surface, and the rotation trajectory of the tool was reduced with wear of the cutting edge. Moreover, the average surface roughness Ra of the groove bottom exceeded 0.1 μm, and the groove bottom was not obtained flat due to damage to the cutting edge. From the results, it has been found that the present invention suppresses the progress of abrasion and enables desired groove processing.

(Example 2)
Inventive Examples 3 to 5 and Comparative Example 6 are the same as those of Inventive Example 1, and R45 degrees and the ratio of the hemispherical surface to the groove are set to 1: 0.5 to 3, and Example 1 is used. A similar test was conducted. Table 1 shows the tool specifications and cutting test results.

  From Table 1, Examples 3 to 5 of the present invention had a maximum wear amount of 7 μm or less at the time of cutting 200 m, and the progress of wear could be suppressed. This is considered to be because wear was suppressed and the rotation trajectory of the tool could be maintained by providing a sufficient hemispherical width. From this result, it was found that by setting the ratio of the hemispherical surface to the groove at R45 degrees to 1: 0.5 to 2.5, the wear life can be suppressed and the tool life can be greatly prolonged.

FIG. 1 is a front view of an example of the present invention. FIG. 2 is an enlarged view of FIG. FIG. 3 is a left side view of FIG. FIG. 4 is an explanatory diagram showing the machining state of the present invention. FIG. 5 shows a change in the maximum amount of wear of Example 1 of the present invention. FIG. 6 shows the change in the maximum amount of wear in Comparative Example 2. FIG. 7 is a left side view of another embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tool main body 2 Hemisphere 3 The most advanced part 4 Groove 5 Ridge line 6 Work material

Claims (3)

A rotary cutting tool having a hemispherical surface at the front end of a cylindrical tool body, the hemispherical surface having a plurality of grooves extending from the vicinity of the tool rotation center toward the rear end, and the hemispherical surface The rotary cutting tool for glass processing, wherein the groove ratio is set to 1: 0.5 to 2.5 in the vicinity of R45 degrees of the hemispherical surface. 2. The rotary cutting tool for glass processing according to claim 1, wherein the plurality of grooves are provided from R10 degrees toward the rear end. The rotary cutting tool for glass processing according to claim 1 or 2, wherein the hemispherical surface portion is coated with a hard coating, and the hardness of the hard coating is HV30 GPa or more.

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