JP4341962B2 - Rotary cutting tool with chip disposal function - Google Patents

Description

  The present invention relates to a rotary tool that has a function of treating chips generated when cutting an aluminum alloy or the like, and is particularly suitable for finish cutting.

  Conventionally, as a tool for processing non-ferrous metals such as aluminum alloys, there is a rotary tool that uses a diamond tip as the cutting edge and joins the tip to the main body. One of these tools is for finishing and machining the inner surface of the hole. There is a diamond reamer. A diamond reamer generally has a shaft-shaped main body made of a material such as cemented carbide from the viewpoint of economy, and a small-sized diamond tip is provided only in a portion acting as a cutting edge.

  When a nonferrous metal having ductility such as an aluminum alloy is cut with such a diamond reamer, there has often been a problem that long chips are generated and entangled with the reamer body to make cutting impossible. In particular, in hole machining such as a reamer, since cutting is performed by rotating in a hole, chips are not discharged smoothly, and a problem that chips are more likely to be entangled than a bite or the like occurs.

  In order to solve this problem, in a rotary multi-blade tool to which a diamond tip is bonded, there is a tool provided with a chip breaker on the rake face of the diamond tip, and a specific example of the tool is applied to a reamer. . (For example, see Patent Document 1)

  As for the chip breaker, it is a throw-away chip, not a reamer, but a chip breaker is formed on the upper surface of an ultra-hard sintered body such as diamond, and the surface roughness of this chip breaker is set to the width of the chip breaker. On the other hand, a throw-away tip having a width of at least 5% or more and 50% or less from the cutting edge is formed to 0.8S or less, and the other part is formed to exceed 0.8S and 10.0S or less (for example, There is a throw-away tip (see, for example, Patent Literature 3) in which a chip breaker having a surface roughness of 0.5 S or more and 10.0 S or less is formed on the upper surface of an ultra-high hardness sintered body.

JP 2001-322029 A JP-A-4-217404 JP-A-4-217406

  The cutting tool provided with the chip breaker as described above is excellent in that the chips are finely divided and the discharge performance is improved. However, in the case where the chip breaker described in each of the above patent documents is provided, that is, in which a step is formed on the rake face, there is a tendency that the cutting resistance increases and the sharpness is lowered, and the surface of the machined surface is accompanied with this. The problem of reduced roughness can also occur. This is a big problem in a reamer used for finishing cutting among rotary cutting tools.

  Further, in the chip breaker provided with a step on the rake face, there is a possibility that the chip interferes with the back surface of the chip breaker when the chip flows out, and the chip flows near the cutting point and scratches the work surface. In particular, in the processing in a closed region such as the inner surface processing of a hole, the problem of chip outflow failure increases, and the risk of scratching the processed surface increases.

  Furthermore, this is not required for throw-away tips such as Patent Document 2 and Patent Document 3, but for tools in which the tip is fixed to the base material by brazing with a rotary tool such as a reamer, end mill, or milling cutter, the tip is re-polished. Is generally used. When performing this re-grinding, the flank of the bottom cutting edge is polished to restore the sharp cutting edge. However, if a chip breaker is provided, the length from the tip of the cutting edge to the breaker can be reduced. As the length becomes shorter and the performance changes, it is necessary to correct not only the flank surface but also the shape of the breaker. Therefore, re-polishing is not easy, and as a result, the life of the tool will be shortened if it is not re-polished, and if it is re-polished, the processing cost will increase and the meaning of re-polishing will be lost. become.

  For this reason, the present invention proposes a rotary cutting tool that cuts chips and improves chip discharge, and does not reduce sharpness, and can be easily reground and improve tool life. It is.

A feature of the rotary cutting tool of the present invention is a rotary cutting tool in which a tip having an outer peripheral cutting edge and a bottom cutting edge is fixed to one end of a shaft-shaped main body,
The outer peripheral cutting edge and the bottom cutting edge are formed at the boundary between the flank and the rake face consisting of a flat surface, and the outer peripheral cutting edge and the rake face of the bottom cutting edge are formed in the same plane,
Among the rake faces, the rake face on the side on which the outer peripheral cutting edge is formed has a surface roughness Rz of 0.2 μm or less, and the other rake faces have a surface roughness of 1 to 5 μm.

  The present invention provides a flat surface without providing a chip breaker having a step on the rake face, and increases the frictional resistance between the chip and the rake face by increasing the surface roughness of the rake face, thereby dividing the chip. It has a function. By doing so, the bottom cutting edge can be re-polished while having the function of a chip breaker, and the tool life can be greatly improved without deteriorating the sharpness. In addition, since the rake face on the side where the outer peripheral cutting edge is formed has reduced surface roughness and improved the precision of the cutting edge, there is almost no need for re-polishing, and re-polishing is the polishing of the flank face of the bottom cutting edge. It is easy because it is only necessary.

  The width of the rake face on the side where the outer peripheral cutting edge is formed is preferably 20 to 100 μm. The reason why it is 20 μm or more is to maintain the sharpness and hole finishing accuracy, and the reason why it is 100 μm or less is that the chip disposal function is not impaired.

  The rotary cutting tool of the present invention is suitable for finish cutting of the inner surface of a hole. In this invention, since it is excellent in the cutting | disconnection effect | action of a chip as mentioned above and can be set as a tool with a favorable sharpness, the effect becomes large especially when it uses for finish cutting.

  The rotary cutting tool of the present invention has a chipper on the rake face and does not have a step, so that the cutting performance is good, and the surface roughness of the rake face is roughened to have a breaker function by frictional resistance with chips. As a result, chip discharge is enhanced. Further, since the chip breaker is not provided on the rake face, re-polishing is easy, and the tool life can be improved without reducing sharpness.

  A diamond reamer will be described as an example of the rotary cutting tool of the present invention. 1A and 1B are diagrams showing a diamond reamer which is a rotary cutting tool of the present invention. FIG. 1A is a front view and FIG. 1B is a right side view. 2 is a partially enlarged view of the periphery of the tip of the diamond reamer of FIG. 1. FIG. 2 (a) is a view from the rake face side of the tip, and FIG. 2 (b) is a view from the flank side of the outer peripheral cutting edge of the tip. FIG. 3 is a perspective view of the peripheral portion of the diamond reamer chip of FIG. In this diamond reamer, a shank for attaching a chip is provided on one end side of a shaft-shaped main body 1, and a chip 2 is provided in the portion of the shank. The main body 1 is made of cemented carbide or the like, and the chip 2 is made of a cemented carbide 2b on which a sintered diamond 2a is formed, and is fixed to the main body 1 by brazing or the like. The chip 2 is provided with a flat rake face 3 and two flank faces 4a and 4b. A bottom cutting edge 5 is formed at the intersection ridgeline between the rake face 3 and the flank 4a, and an outer peripheral cutting edge 6 is formed at the intersection ridgeline between the rake face 3 and the flank 4b. Further, a chamfered surface 7 obtained by chamfering is formed at the intersection of the flank surfaces 4a and 4b.

  Of the rake face 3, the surface 3a on the side forming the outer peripheral cutting edge 6 has a surface roughness Rz of 0.2 μm or less, and the other part 3b has a surface roughness Rz of 1 to 3 μm. Yes. The surface 3a having a small surface roughness is formed with a width of 20 to 100 μm along the outer peripheral cutting edge ridge line. Therefore, the outer peripheral cutting edge 6 is a sharp cutting edge with high cutting edge accuracy. Further, the bottom cutting edge 5 has a cutting edge formed by the intersecting ridge line between the rake face 3b and the flank 4b having a large surface roughness, and the precision of the cutting edge is lower than that of the outer peripheral cutting edge 6. Further, an oblique cutting edge 8 formed by the intersection of the chamfered surface 7 and the rake face 3 is formed at the intersection of the outer peripheral cutting edge 6 and the bottom cutting edge 5. As with the outer peripheral cutting edge 6, the cutting edge has a high precision and sharp cutting edge, and the cutting edge on the inner peripheral side is cut by the ridge line between the rake face 3 b having a rough surface and the chamfered surface 7. Since it is formed, the precision of the cutting edge is lower than that of the outer peripheral side. Since this diagonal cutting edge 8 mainly plays the same role as the bottom cutting edge 5, the cutting edge of the outer peripheral side portion that acts most at the time of machining among the diagonal cutting edge 8 that processes the bottom of the hole and the bottom cutting edge 5 is highly accurate. With a sharp cutting edge, good sharpness is sustained, and the cutting edge on the outer peripheral side decreases before the inner peripheral cutting edge decreases, making it unusable. Absent.

  Although the diamond reamer is mentioned as an example of the rotary cutting tool of this invention, it can apply also to a drill, a milling machine, an end mill, etc. besides this. Among these, it is particularly suitable for a reamer, milling machine, end mill or the like used for finish cutting.

  As the diamond reamer of the present invention, the one shown in FIGS. After forming the chip 2 into a predetermined shape, the outer peripheral side of the rake face 3 was lapped to form a rake face 3a, and the inner peripheral side was formed with a rough rake face 3b by electric discharge machining. Next, the flank surfaces 4a and 4b and the chamfered surface 7 were lapped to form the outer peripheral cutting edge 6, the bottom cutting edge 5, and the oblique cutting edge 8. The rake face 3a has a width of 50 μm, the surface roughness Rz is 0.1 μm, and the rake face 3b has a surface roughness Rz of 2 μm.

  For comparison, a reamer having no chip breaker function shown in FIG. 4 and a reamer having a chip breaker shown in FIG. 5 were manufactured as conventional diamond reamers. For reamers that do not have a chip breaker function, the rake face 3 is lapped and the flank faces 4a and 4b and the chamfered face 7 are lapped to form the outer peripheral cutting edge 6, the bottom cutting edge 5, and the oblique cutting edge 8. did. The surface roughness of the rake face 3 is 0.1 μm in Rz. On the other hand, for the reamer having a chip breaker, a chip breaker 8 is provided by forming a step at the tip corner of the chip 3 by electric discharge machining as shown in FIG. Thereafter, the rake face 3 was lapped and the flank faces 4a and 4b and the chamfered face 7 were lapped to form an outer peripheral cutting edge 6, a bottom cutting edge 5, and an oblique cutting edge 8. The surface roughness of the rake face 3 is 0.1 μm in terms of Rz, but the surface roughness of the rake face 8a in the portion of the chip breaker 8 is 2 μm in terms of Rz.

  These reamers were used to finish holes formed in the aluminum raw material in advance. As a result, the reamer of the present invention had low cutting resistance and good sharpness, chips did not wrap around the chip or the main body, the inner surface of the processed hole was in good condition, and no flaws were generated. Further, the workpiece was not welded to the rake face of the chip. On the other hand, the conventional reamer having no chip breaker function has a low cutting resistance and good sharpness, but the chips are curled for a long time, causing a problem of winding around the chip and the main body. Note that no welding occurred. In addition, the conventional reamer having a chip breaker showed a tendency to increase the cutting resistance, and a phenomenon that the sharpness deteriorated was observed. The chips were not broken around the chip or the main body and were broken into small chips, but the inner surface of the processed hole was bad and many scratches were generated. Moreover, a phenomenon in which welding occurs on the rake face of the chip breaker portion was observed.

  The rotary cutting tool of the present invention can be suitably used particularly for a reamer, a milling cutter, an end mill, etc. used for finish cutting.

It is a figure which shows the diamond reamer of this invention, (a) is a front view, (b) is a right view. It is the elements on larger scale of the chip | tip peripheral part of the diamond reamer of FIG. 1, (a) is the figure seen from the rake face side of a chip | tip, (b) is the figure seen from the flank side of the outer periphery cutting edge of a chip | tip. The perspective view of the chip | tip periphery part of the diamond reamer of FIG. The perspective view of the chip | tip peripheral part of the reamer which does not have the conventional chip breaker function. The perspective view of the chip | tip peripheral part of a reamer with the conventional chip breaker.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main body 2 Tip 3 Rake face 3a Rake face 3b with small surface roughness Rake face 4 with rough surface roughness 4 Relief face 4a Relief face of outer peripheral cutting edge 4b Relief face of bottom cutting edge 5 Bottom cutting edge 6 Outer peripheral cutting edge 7 Chamfering Surface 8 diagonal cutting edge

Claims (3)

A rotary cutting tool in which a tip having an outer peripheral cutting edge and a bottom cutting edge is fixed to one end of a shaft-shaped main body,
The outer peripheral cutting edge and the bottom cutting edge are formed at the boundary between the flank and the rake face consisting of a flat surface, and the outer peripheral cutting edge and the rake face of the bottom cutting edge are formed in the same plane,
Among the rake faces, the rake face on the side forming the outer peripheral cutting edge has a surface roughness Rz of 0.2 μm or less, and the other rake face has a surface roughness of 1 to 5 μm. Cutting tools.   The rotary cutting tool according to claim 1, wherein the width of the rake face on the side forming the outer peripheral cutting edge is 20 to 100 µm.   The rotary cutting tool according to claim 1 or 2, wherein the rotary cutting tool is used for finish cutting of an inner surface of a hole.

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