JP4623674B2 - Rotary cutting tool - Google Patents

Description

  The present invention relates to a rotary cutting tool for machining a blind hole formed in various materials, and more particularly to a rotary cutting tool for finishing a blind hole formed in a non-ferrous material such as an aluminum alloy.

  The valve body, which is one of the key parts of automobiles, is made of materials such as aluminum die-casting, but the structure has become more complex as the parts are consolidated, and the holes for hydraulic control have become multi-stage shapes. It is made up of a number of holes with a general shape. In order to perform such hole finishing, for example, a reamer using a diamond sintered body for a cutting edge is used. When processing with this reamer, chips may be wound around the reamer depending on the processing form, and problems such as reduced work efficiency and scratches on the processed surface are likely to occur. In particular, if the shape of the machined part is not a through hole but a blind hole, the chip discharge performance will deteriorate, and the chip will wrap around the cutting edge, or the chip will remain in the hole after machining, and the chip will be processed in the next process. Problems such as the need to reduce production efficiency arise. Conventionally, as a measure to prevent cutting chips from being wrapped around the cutting edge with a cutting tool, there has been a method of dividing the chip by giving a chip break function to the cutting edge chip, and its typical shape is on the rake face of the chip. The chip is divided by providing a step in the chip.

As an example of a cutting tool in which a step is provided on a rake face to give a break function, there are tools described in Patent Document 1, Patent Document 2, and Patent Document 3. As shown in FIG. 5, the tool disclosed in Patent Document 1 is a tool in which a high-hardness sintered body 22 having a cutting edge is brazed to a shank 21, and a shank continuous with a rake face 23 of the high-hardness sintered body 22. 21 is provided with a chip disposal protrusion 29 on the rake face. This tool has a simple structure and can improve chip disposal even with a tool provided with a high-hardness sintered body 22, and can easily control the direction, length and shape of chips during cutting. Has been. Further, as shown in FIG. 6, the tool described in Patent Document 2 is a cutting tool having a diamond or CBN ultra-hard sintered body 32, and a chip breaker 39 having a complicated three-dimensional shape is provided on a rake face 33. The chip breaker 39 having a complicated three-dimensional shape is provided and can be excellent in chip disposal. Furthermore, as shown in FIG. 7, the tool described in Patent Document 3 is provided with a first rake face 43 a extending from the cutting edge and a rear position of the first rake face 43 a and is higher in height than the first rake face 43 a. A wall surface 50 that connects the second rake face 43b, a rear edge of the first rake face 43a, and a front edge of the second rake face 43b is provided, a notch 45 is provided in the cutting edge, and the wall face 50 is parallel to the cutting edge. This is a structure extending in the direction. According to this structure, not only the length direction of the chips is divided, but also the width direction of the chips is divided into small pieces by the notch portion 45, so that the chips can be made smaller and the discharge performance can be improved. Is.
JP2003-340615A JP 2004-223648 A JP 2007-44833 A

  However, there are various problems when the chip processing protrusion having the structure described in Patent Document 1 and the chip breaker having the structure described in Patent Document 2 are provided in a rotary cutting tool such as a reamer for machining a blind hole. appear. In the case of such a rotary cutting tool, the cutting edge is provided with an outer peripheral cutting edge in the outer peripheral axial direction and a tip cutting edge is provided in the radial direction of the tool tip. Generate chips. Since the tip cutting edge has a long portion that acts simultaneously during processing, the width of the generated chips is widened. When the breaker having the structure as described in Patent Documents 1 and 2 is provided on the rake face, the chips generated from the cutting edge are divided and shortened in the length direction, but the width of the chips is reduced as described above. Since it is large, chips are still large even if divided in the length direction, and even though it can be prevented from being wound around the cutting edge, the discharge performance is not improved. In addition, when machining a blind hole, there is a problem that chips are likely to be accumulated in the hole, so that the discharge property is worse, and a problem that the roughness of the processed surface becomes rough or the cutting edge is chipped easily occurs.

  In order to solve this problem, there is a tool described in Patent Document 3, but with this tool, it is possible to divide the chips into small pieces to improve the discharge performance, but in order to provide a notch in the cutting edge, Of the surface processed by the cutting edge, there is a possibility that uncut portions may occur in the notched portion or the accuracy of the processed surface is deteriorated. In addition, the cutting edge near the notch is likely to be chipped, resulting in a problem that the life is shortened. In addition, when the cutting edge is worn and re-polished to regenerate the cutting edge, if there is a notch, it is necessary to remove it once, so the number of times that re-polishing can be performed is reduced. Becomes shorter.

  For this reason, the present invention can efficiently discharge chips even in the case of a rotary cutting tool that processes holes such as blind holes where chips are difficult to be discharged. The present invention proposes a rotary cutting tool that is difficult to worsen, can be easily re-polished at the cutting edge, and can prolong the service life.

The present inventor can divide the chips in the width direction while maintaining the strength of the cutting edge by incorporating a device in the shape of the breaker, and can reduce the chips and improve the discharge performance. I found the shape.
A feature of the rotary cutting tool of the present invention is that a tip is provided at the tip of a shaft-like base material, a tip cutting edge is provided in a radial direction of the base material on the tip side of the tip, and on the outer peripheral side of the tip. Is a rotary cutting tool provided with an outer peripheral cutting edge, and a breaker piece is provided on the rake face of the chip, and faces the tip side of the chip among the surfaces constituting the breaker piece, and a rotation shaft. The intersecting surface is provided with a convex portion having a substantially V-shaped cross section in a direction parallel to the rake face.

  In this way, the surface of the breaker piece that faces the tip side of the chip and intersects the rotation axis, that is, the chips generated by the tip cutting edge flow on the rake face of the chip, and the chips flow. By providing a V-shaped convex part toward the tip of the tool on the surface in contact with the breaker piece, the width direction of the chip is divided, and the chip is forced to curl by flowing in contact with the breaker piece. Since the length direction is also divided, the chips are divided into small pieces. Therefore, chips can be efficiently discharged even when processing holes such as blind holes where chips are difficult to be discharged.

  The size w of the convex portion is preferably 0.2 to 1.0 mm. The size of 0.2 mm or more is a size necessary for the convex portion to effectively act on the chips, and the size of 1.0 mm or less causes the chips to be welded and the welded material to the recesses. It is because it becomes easy to accumulate. In addition, the size w of the convex portion referred to in the present application is a protruding amount of the convex portion when viewed in a cross section parallel to the rake face of the chip as shown in FIG.

  When the rake face is viewed from the vertical direction, the angle α between the surface provided with the convex portion and the radial line is preferably 5 to 30 °. By doing in this way, when the chip generated at the tip cutting edge flows while contacting the surface having the convex part of the breaker piece, a force to twist the chip toward the outer peripheral side is applied, and a force is applied in the width direction of the chip. Therefore, it becomes easy to be divided in the width direction.

  It is preferable that a curved surface having a size of R of 0.15 to 1.0 mm is provided at the tip of the convex portion. By doing in this way, since resistance is locally applied to the chips, it becomes easy to be divided in the width direction.

  Even in processing that generates wide chips with the cutting edge of a rotary cutting tool, it is easy to divide the chips in the width direction, and the size of the chips in the width direction can be controlled, so chips such as blind holes can be discharged. Even when processing a hole that is difficult to be formed, chips can be made smaller and discharged efficiently. Thereby, the precision of a processing surface can be improved, damage to a cutting edge can be prevented, re-polishing of a cutting edge is also easy, and lifetime can be lengthened.

  As a rotary cutting tool of the present invention, a diamond reamer having a chip made of a diamond sintered body will be described as an example. 1 and 2 are diagrams showing an outline of the reamer of the present invention. FIG. 1 is a perspective view, FIG. 2 (a) is a front view, and FIG. 2 (b) is a plan view. FIGS. 3 and 4 are views showing a breaker piece provided on a chip, both of which are (a) a plan view and (b) a side view.

  Referring to FIGS. 1 and 2, the reamer of the present invention is provided with a bottom surface 1a and a side surface 1b of the nuisance portion on the distal end side of the shaft-shaped main body 1, thereby forming a suspicious portion. A chip 2 made of a diamond sintered body is joined by brazing or the like. In addition, the part to which the chip 2 is joined is further dug out from the bottom part 1a of the pussies and is recessed by the thickness of the chip, and the rake face 3 of the chip 2 and the bottom part 1a of the pussies are on the same plane. A tip cutting edge 5 is formed at the boundary between the rake face 3 and the tip flank 4b on the tip side of the chip 2, and an outer peripheral cutting edge is formed at the boundary between the rake face 3 and the outer flank 4a. 6 is formed. Further, a chamfered surface 7 is formed at the boundary between the outer peripheral flank 4 a and the tip flank 4 b, and an oblique cutting edge 8 is formed at the boundary between the rake face 3 and the chamfered surface 7.

  A breaker piece 9 is provided on the rake face 3 of the chip 2 and on the bottom surface 1 a of the body 1 of the main body 1 so as to straddle both, and the breaker piece 9 is attached to the bottom surface 1 a of the waste section 1 or the chip 2 via the mounting hole 11. It is fixed with screws. Of the surfaces constituting the breaker piece 9, a convex portion 10 a is provided on the surface 10 facing the tip side of the chip 2 and intersecting the rotation axis.

  With reference to FIG. 3, the magnitude | size w of the convex part 10a provided in the breaker piece 9 is 0.2-1.0 mm. A concave portion 10b is provided between the convex portions 10a, and the surface 10 of the surface constituting the breaker piece 9 that faces the tip side of the chip 2 and intersects the rotation axis has an uneven shape. The direction y of the surface 10 is provided with an angle α of 5 to 30 ° with respect to the radial line x, whereby when chips generated from the tip cutting edge 5 flow on the rake face 3 and contact the convex portion 10a. When the chips flow on the surface 10, a twisting force is applied and the chips are easily divided in the width direction. Further, a curved surface having a R size of 0.15 to 1.0 mm is provided at the tip of the convex portion 10a, and the contact area with the chips becomes small, so that the twisting force against the chips is locally obtained. It becomes easy to be divided by the width direction.

  FIG. 4 shows a breaker piece different from FIG. The number of convex portions 10a provided on the breaker piece 9 is smaller than that shown in FIG. 3, and the concave portions 10b between the convex portions 10a have a planar shape. Others are the same as those shown in FIG.

  A diamond reamer according to the present invention is provided with a breaker piece having the shape shown in FIG. 4 (present inventions 1 to 17), and a conventional diamond reamer is provided with a breaker piece having the shape shown in FIG. 8 (Comparative Examples 1 and 2). ) And a breaker having the shape shown in FIG. 9 (Comparative Example 3) with a cutting edge provided with a notch, the situation where chips are cut, the state of chipping of the cutting edge, the accuracy of the machining surface, A comparative test was conducted on the situation where chips remained after processing.

  The cutting situation in the width direction of the chip is evaluated in four stages, ◎ is that most chips are divided in the width direction and the chips are fine, ○ is mixed with chips that are not divided in the width direction However, it is assumed that there are many that are divided in the width direction, Δ is that there are few that are divided in the width direction, and there are many that are not divided, and x is that there is almost no division in the width direction. As for the situation where chips remain in the hole, ○ indicates that almost no chip remains in the hole, △ indicates that the chip is discharged to some extent but remains in the hole, and × indicates that it is not discharged. It was assumed that a large amount of chips remained in the holes.

  For all the reamers, a cemented carbide is used as the material of the shaft-shaped main body 1, and as shown in FIG. 1 and FIG. 2, a nose portion bottom surface 1a and a nose portion side surface 1b are formed on the tip side. The tip portion was shaped to be further dug out from the bottom portion 1a of the Nusumi portion.

  In the present inventions 1 to 17 and Comparative Examples 1 and 2, a chip 2 made of a diamond sintered body having the shape shown in FIG. 2 was joined to the dug shape portion by brazing. The amount of dent in the portion of the main body 1 is the same as the thickness of the chip 2, so that the rake face 3 and the Nusumi part bottom face 1 a are on the same plane when the chip 2 is joined. The tip 2 has a tip cutting edge 5 formed at the boundary between the rake face 3 and the tip flank 4b at the tip, and the tip cutting edge 5 coincides with the radius of rotation when the reamer is rotated. It is formed in the direction. Further, the outer peripheral cutting edge 6 is formed at the boundary between the rake face 3 and the outer peripheral flank 4a, and the chamfered surface 7 is formed at the boundary between the outer peripheral flank 4a and the tip flank 4b. An oblique cutting edge 8 is formed at the boundary between 3 and the chamfered surface 7. The rotation radius of the outer peripheral cutting edge 6 was 10 mm.

  In Comparative Example 3, a chip 42 made of a diamond sintered body having the shape shown in FIG. The tip 42 has a first rake face 43a formed by grinding and denting the tip side of the rake face 43, and the rear end side is a second rake face 43b whose height is higher than that of the first rake face 43a. The amount of the dent in the body 1 is the same as the chip thickness of the second rake face 43b. Therefore, when the chip 42 is joined, the second rake face 43b and the Nusumi part bottom face 1a are the same. It is on a plane. The tip 42 has a tip cutting edge 46 formed at the boundary between the first rake face 43a and the tip flank 44b at the tip, and the tip cutting edge 46 has a rotational radius when the reamer is rotated. They are formed in the matching direction. Two cutouts 45 were formed in the tip cutting edge 46. Further, an outer peripheral cutting edge 47 is formed at the boundary between the rake face 43a and the outer peripheral flank 44a, and a chamfered surface 49 is formed at the boundary between the outer peripheral flank 44a and the tip flank 44b. An oblique cutting edge 48 is formed at the boundary between the rake face 43 a and the chamfered face 49. The radius of rotation of the outer peripheral cutting edge 47 was 10 mm.

  The shape of the breaker piece 9 used for the reamers of the present invention 1 to 17 was the one shown in FIG. Of the surfaces constituting the breaker piece 9, convex portions 10 a are formed on the surface 10 facing the tip side of the chip 2 and intersecting the rotation axis, and the convex portions 10 a are formed on the surface 10 at intervals. is doing. Further, the surface 10 is shaped so as to be attached with an angle α with the direction x of the radius of rotation when the reamer is rotated, and the surface 12 facing the outer peripheral side is attached so as to be parallel to the outer peripheral cutting edge 6. . The shape of the breaker piece 9 used in the reamers of Comparative Examples 1 and 2 is the shape shown in FIG. 8, and the surface 10 that faces the tip side of the chip 2 and intersects the rotation axis has no projection. . In any reamer, the surface 10 is not perpendicular to the rake surface 3 and is inclined at an angle β so that chips can easily flow, and a mounting hole 11 is provided in the center of the breaker piece 9. Yes. In this embodiment, the angle β is 10 °. The above-mentioned breaker piece 9 was placed on these so as to straddle the rake face 3 of the chip 2 and the bottom face 1a of the Nusumi part, and fixed with screws using the attachment holes 11.

  About the reamer of this invention 1-17, the size w of the convex part 10a of the breaker piece 9 and the distance from the front-end cutting edge 5 to the front-end | tip of the convex part of the breaker piece 9 (here, the most tip among several convex parts 10a) The distance from the one close to the cutting edge 5 to the tip cutting edge 5), the R size of the tip of the convex portion 10a, and the angle α between the surface 10 and the direction x of the rotation radius when the reamer is rotated are different. Products were manufactured, and the difference in effect due to the difference was compared. The specifications of the breaker piece 9 are as shown in Table 1. In Comparative Examples 1 and 2, the distance from the tip edge 5 to the surface 10 of the breaker piece 9 was 1.7 mm, and the angle α of the surface 10 was varied. In Comparative Example 3, the distance from the tip cutting edge 46 to the wall surface 50 (corresponding to the surface 10 of Comparative Examples 1 and 2) connecting the rear edge of the first rake face 43a and the front edge of the second rake face 43b is 1. The wall surface 50 was perpendicular to the first rake face 43a. Moreover, since the comparative example 3 provided the level | step difference in the rake face 43 of the chip | tip 42 and made this into the breaker, the breaker piece is not provided. Specifications other than those described above are the same for all reamers.

Using these reamers, finishing processing of the blind hole of the valve spool (hole φ20 mm, depth 40 mm) of the ADC12 equivalent material was performed 3000 times, and the situation at that time was confirmed. The processing conditions were a rotational speed S = 2400 min ⁻¹ and a feed speed F = 240 mm / min. Table 1 shows the results of the above tests.

  When comparing the present inventions 1 to 5 and seeing the effect due to the difference in the size of the projections, the one with a size of 0.1 mm (invention 5) tends to be a little worse in the dividing state in the width direction, It turns out that an effect becomes small when too small. In the case of the size of 1.2 mm (Invention 4), the state of division in the width direction was good, but a slight amount of chip welding was observed in the concave portion.

  Comparing the present invention 1 with 6-8, and looking at the effect due to the difference in distance from the cutting edge to the tip of the convex part of the breaker piece, the distance is as small as 2.7 mm (invention 8), it is small There was a tendency for the fragmentation in the width direction of the chips to be a little worse than. It is considered that this is because the force generated when the chips generated by the tip cutting edge and flowed on the rake face come into contact with the convex portion of the breaker piece becomes weaker as the distance increases, and thus it becomes difficult to be divided in the width direction.

  Comparing the present invention 1 with 9 to 13 and looking at the effect of the difference in the size of R at the tip of the convex portion, R is as small as 0.1 mm (present invention 13) or as large as 1.2 mm (present) In the invention 12), the cutting situation in the width direction of the chips tended to be a little worse. In particular, when R is 0.1 mm, it is considered that the chipping and wear of the convex portions are observed as the processing is repeated, and therefore the cutting situation is deteriorated.

  Comparing the present invention 1 with 14-17, and looking at the effect of the difference in the angle α of the surface of the breaker piece, those having an angle of 0 ° (present invention 17) and 40 ° (present invention 16) are chips. There was a tendency for the fragmentation in the width direction to become worse. If the angle is set to some extent, the twisting force is applied to the chips, so the effect of dividing in the width direction is considered to be large. However, if the angle is too large, such as 40 °, the convex part does not act effectively on the chips and It seems that the fragmentation situation of the chips deteriorated because of running away.

  As in Comparative Examples 1 and 2, the surface where the chip of the breaker piece is not in contact has no projection, the effect of dividing in the width direction of the chip is not obtained, and a considerable amount of chip remains in the processed hole, It was confirmed that the discharge was poor. In addition, in the case where the cutting edge was provided on the cutting edge as in Comparative Example 3, the effect of dividing the chips in the width direction was seen, but the cutting edge around the cutting edge was chipped, and the accuracy of the machining surface There was a tendency for the life to be shortened with worsening.

  As can be seen from the above, according to the reamer of the present invention, it is possible to improve the chip discharge performance by dividing the chips in the width direction, improve the accuracy of the machined surface, and cut the chips. The life can be improved by preventing chipping of the blade.

  The present invention can be used for various rotary cutting tools such as drills and end mills having tip cutting edges in addition to reamers.

The perspective view which shows the example of the rotary cutting tool of this invention. It is a figure which shows the example of the rotary cutting tool of this invention, (a) is a front view, (b) is a top view. It is a figure which shows the example of the breaker piece attached to the rotary cutting tool of this invention, (a) is a top view, (b) is a side view. It is a figure which shows another example of the breaker piece attached to the rotary cutting tool of this invention, (a) is a top view, (b) is a side view. It is a figure which shows the example of the conventional cutting tool with a breaker, (a) is a top view, (b) is a side view. It is a figure which shows another example of the conventional cutting tool with a breaker, (a) is a top view, (b) is a side view. It is a figure which shows another example of the conventional cutting tool with a breaker, (a) is a top view, (b) is a side view. It is a figure which shows the example of the breaker piece attached to the conventional rotary cutting tool, (a) is a top view, (b) is a side view. It is the elements on larger scale which show the chip periphery attached to the reamer of the comparative example 3 in an Example, (a) is a top view, (b) is a side view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main body 1a Nusumi part bottom face 1b Nusumi part side surface 2 Tip 3 Rake face 4a Peripheral flank face 4b Tip flank face 5 Tip cutting edge 6 Perimeter cutting edge 7 Chamfering face 8 Diagonal cutting edge 9 Breaker piece 10 The tip side of the tip is rotated Surface 10a intersecting with axis Protruding portion 11 Mounting hole 12 Surface facing outer peripheral side

Claims (2)

Rotating cutting in which a tip is provided at the tip of a shaft-shaped base material, a tip cutting edge is provided in the radial direction of the base material on the tip side of the tip, and an outer peripheral cutting edge is provided on the outer peripheral side of the tip A tool,
A breaker piece is provided on the rake face of the chip, and a surface of the breaker piece that faces the tip side of the chip and intersects the rotation axis has a direction parallel to the rake face. Protrusions having a substantially V-shaped cross section are provided ,
The size w of the convex portion is 0.2 to 1.0 mm,
A rotary cutting tool for machining a blind hole in which a curved surface having a size of R of 0.15 to 1.0 mm is provided at the tip of the convex portion .   2. The rotary cutting tool according to claim 1, wherein an angle α between the surface on which the convex portion is provided and the radial line when the rake face is viewed from the vertical direction is 5 to 30 °.

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