JP5441871B2 - Throw-away end mill and throw-away tip used therefor - Google Patents

Description

  The present invention relates to a throw-away end mill used as a rotary tool, particularly to a throw-away end mill with a bottom blade capable of three-dimensional cutting and a throw-away tip used therefor.

  In a throw-away end mill capable of three-dimensional cutting, as a form of machining, in addition to shoulder machining and grooving, there is a cutting edge to the end mill axis, so that it sinks obliquely to the work material. Such a process or a process of sinking vertically in the axial direction like drilling is possible, and a throwaway tip having a substantially parallelogram has been conventionally used for such a three-dimensional end mill.

  6 to 9 show a three-dimensional end mill as a conventional example. 6A and 6B show a throw-away tip 17 of a conventional example. FIG. 6A is a plan view, FIG. 6B is a short side view, and FIG. 6C is a long side view. FIG. 7 is a cross-sectional view taken along the line CC in FIG. 8 is a side view of the end mill with the conventional throw-away tip 17 attached to the end mill body 18, and FIG. 9 is a bottom view of FIG. As shown in FIG. 8, the first tip is attached to the end mill body 18 with the long side cutting edge 19 as the outer peripheral edge and the short side cutting edge 20 as the bottom edge, and the second tip has the long side cutting edge 19 as the second tip. The bottom edge is attached to the end mill body 18 with a short edge 20 as an outer peripheral edge. (For example, refer to Patent Document 1.)

  Here, the long cutting edge of the second tip is used as a bottom cutting edge which is the cutting edge on the front side of the end mill. The bottom cutting edge covers from the outer periphery of the machining diameter to the end mill axis. It is a necessary condition. Further, in such a three-dimensional end mill, since a normal end mill process such as a shoulder process or a grooving process is also performed, it is common that the side cutting edge has a positive axial rake angle. Further, in the conventional chip, a positive rake angle is attached to the long side cutting edge and the short side cutting edge, and the breaker wall height is lower than the cutting edge ridge line as shown in FIG. Incidentally, the height of the cutting edge ridge line with respect to the seating surface is constant for both the long edge cutting edge and the short edge cutting edge.

JP-A-8-323527

  However, when the insert as described above is attached to the throwaway end mill with a positive axial rake angle, the breaker wall surface is hidden by the short edge cutting edge when viewed from the bottom of the end mill as shown in FIG. As a result, the chip breaker has a small effect, and as a result, the chip processing performance during drilling has been extremely poor.

The chips are discharged in a long and extended state without being cut finely, and in severe cases, the long extended chips get tangled in the end mill body. It must be paused, resulting in reduced machining efficiency. In order to solve the above problem, when performing drilling with the end mill, step machining, which is a machining method in which the tool is intermittently advanced so that the chips are forcibly cut finely, is used. However, in this case as well, there is a problem that the processing efficiency is reduced with respect to the continuous processing. In addition, as another problem caused by the chips not being cut finely and extending for a long time, the chips are elongated and become heavy, and are scattered in all directions by centrifugal force. This is especially dangerous when used on machine tools without protective covers.

  The present invention has been made to solve the above-described problems of the prior art, and in a throw-away end mill capable of three-dimensional cutting, it is possible to improve the chip processability of the bottom edge of a short edge cutting edge and perform drilling. The purpose is to enable continuous machining, improve machining efficiency and secure safety.

The throw-away end mill of the present embodiment has a short-side cutting edge and a long-side cutting edge at the crossing ridge formed by the side surface and the top surface of the polygonal plate-shaped tip body at the tip of the substantially cylindrical tool body. The first tip is attached to the tool body with the long side cutting edge as the outer peripheral edge and the short side cutting edge as the bottom edge, and the second tip is provided with the second tip. as chip end cutting edge of the long side cutting edge, the bottom edge the a throw-away end mill is attached to the tool body a short side cutting edge as outer peripheral cutting edge, before Symbol first chip on the rake face breaker wall is provided along, at the distal end face view of the tool body, the bottom blade, concave der Rutotomoni made gradually lower toward the center thereof, said breaker wall at its central portion the seating surface of the chip body toward Characterized in that it is a gradually becomes higher convex shape as a quasi.

  According to such a configuration, the chip at the time of drilling in the bottom blade of the first tip is, as a first step, a cutting whose cross section is a concave shape along the bottom blade whose central portion is a low concave shape. Waste is discharged. As a second step, braking is performed by hitting a breaker wall provided along the bottom blade. At this time, since the center part of the bottom blade is low, the center part of the chip hits the breaker wall first, and the contact length between the chip and the breaker wall becomes longer at the center part of the breaker wall. Chips tend to clog. On the other hand, the contact length between the chip and the breaker wall is short at both ends. Therefore, only the vicinity of the center becomes clogged in the cross section of the chip, so that machining distortion occurs, and the chip is easily divided from that point. As a result, since drilling can be performed by continuous machining, machining efficiency can be improved and safety can be ensured.

  ADVANTAGE OF THE INVENTION According to this invention, the throwaway end mill which can improve chip efficiency of a bottom blade, enables drilling to be performed by continuous machining, and realizes improvement of machining efficiency and securing of safety. It is possible to provide a throw-away tip used for the above.

It is the schematic of the throw away tip of this invention, (a) Top view, (b) Short side side view, (c) Long side side view. It is AA sectional drawing of Fig.1 (a). It is BB sectional drawing of Fig.1 (a). FIG. 2 is a side layout diagram when the throw-away tip of FIG. 1 is mounted on a tool body. FIG. 5 is a bottom plan view of FIG. 4. It is the schematic of the throwaway tip of a prior art example, (a) Top view, (b) Short side side view, (c) Long side side view. It is CC sectional drawing of Fig.6 (a). FIG. 7 is a side layout diagram when the throw-away tip of the conventional example of FIG. 6 is mounted on a tool body. FIG. 9 is a bottom plan view of FIG. 8. It is the schematic of the arrangement | positioning relationship of the 1st chip | tip of this invention, and a 2nd chip | tip.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 5 and FIG. 10 show an embodiment of the present invention. FIG. 1 (a) is a plan view of a throw-away tip 1 according to the present embodiment, (b) is a side view of a short side, and FIG. ) Is a side view of the long side, FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1A, FIG. 3 is a cross-sectional view taken along the line BB in FIG. FIG. 5 is a bottom view of FIG. 4. FIG. 5 is a side view of the end mill in a state where it is mounted on the end mill body 14.

  In FIG. 1, the throw-away tip 1 according to the present embodiment is a substantially parallelogram plate shape in which a short side cutting edge 6 and a long side cutting edge 7 are provided on an intersecting ridge formed by a side surface 4 and an upper surface 5 of the chip body. The corner portion where the long side cutting edge 7 and the short side cutting edge 6 intersect is connected by an arcuate ridgeline, and the side where the long side cutting edge 7 and the short side cutting edge 6 intersect at an acute angle is the corner cutting edge 8 is used.

  In the side view, the cutting edge height of the long edge cutting edge 7 is constant with respect to the seating surface 9, but the cutting edge height near the center of the short edge cutting edge 6 is lower than both ends, and is arcuate. It is a concave curve. Further, a screw hole 10 for tip screwing penetrating to the seating surface 9 is formed in the center portion of the chip upper surface 5.

On the top surface 5 of the chip, a rake surface 11 having a positive rake angle is formed continuously with the long edge cutting edge 7, a groove bottom surface 12 parallel to the seating surface 9, and the vicinity of the screw hole 10 is raised from the groove bottom surface 12. A breaker projection 13 is formed. As shown in FIG. 2, a rake angle is not provided at the center of the short side cutting edge 6, and the rake face parallel to the seating surface 9 is connected to the breaker wall 13 a of the breaker protrusion 13. Here, the breaker wall 13a formed along the short side cutting edge 6 has a concave shape in which the short side cutting edge 6 is gradually lowered toward the central portion thereof, and the breaker wall 13a is directed toward the central portion thereof. In addition to the convex shape gradually becoming higher, the breaker wall 13a has a convex shape that gradually approaches the short edge 6 toward the center thereof.

  Here, as shown in FIG. 2, the step height h1 between the height of the cutting edge and the height of the breaker wall 13a is the largest in the vicinity of the center of the short edge cutting edge 6, and both ends of the short edge cutting edge 6 as shown in FIG. The level difference h2 between the cutting edge height and the height of the breaker wall 13a is the smallest. In this embodiment, as shown in FIGS. 2 and 3, the breaker width w1 near the center of the short edge cutting edge 6 is the narrowest and the breaker width w2 at both ends is widened. .

  Moreover, as shown in FIG.2 and FIG.3, the rake face 6a along the said short edge cutting edge 6 has a rake angle of both ends (refer FIG. 3) large compared with another part (refer FIG. 2). 2 and 3, the rake angle is positive only at both ends of the short edge cutting edge 5, while the rake face 6 a is flat in other portions, that is, the seating surface 9 and They are formed in parallel.

  According to this configuration, since the rake angle is increased at both ends of the short side cutting edge 6 to improve the sharpness, the cutting resistance is reduced and the flow of chips at these both ends is smoother. Become. As a result, the processing distortion at the center of the chip is further increased, which promotes chip breaking.

  4 is a side view of the throw-away end mill with the tip 1 mounted on the end mill body 14, and FIG. 5 is a bottom view of FIG.

  Here, the throw-away end mill includes a first tip 15 and a second tip 16, and at least two throw-away tips. Of these chips, the first chip 15 is the throw-away chip 1 shown alone in FIGS. 1 to 3.

  The first tip 15 is attached to the end mill body 14 with the long side cutting edge 7 as the outer peripheral edge 32 and the short side cutting edge 6 as the bottom edge 30, and the second tip 16 has the long side cutting edge at the bottom. As the blade 31, a short side cutting edge is attached to the end mill body 14 as an outer peripheral edge 33.

  In the first tip 15, the step between the bottom blade 30 and the breaker wall 13 a is the largest near the center, and the step between the cutting edge height and the breaker height at both ends of the bottom blade is the smallest. In this embodiment, as shown in FIGS. 2 and 3, the breaker width is narrowest in the vicinity of the center of the bottom blade, and the breaker widths at both ends are widened.

  Due to the above-described characteristic shape, the chip at the time of drilling in the bottom blade 30 of the first chip 15 is first cut along the bottom blade 30 having a concave shape at the center part. The waste is discharged and then braked by hitting the breaker wall 13a provided along the bottom blade 30. Next, the breaker wall 13a has a convex shape that gradually increases toward the central portion thereof, and further has a convex shape that gradually approaches the bottom blade 30 toward the central portion, so that the cutting blade height and the breaker wall height are increased. The bottom edge is the largest at the center of the bottom blade and both ends are small, so that the chips discharged from the bottom blade 30 are easily clogged at the center and the flow of the chips is slow. On the other hand, the chips flow smoothly at both ends, so that the flow of chips is fast. By clogging only the vicinity of the center in the chip in this way, machining distortion is generated, and the cutting of the chip can be promoted starting from that.

  In addition to the above-described configuration, it is preferable that the width of the breaker is narrowest at the center portion of the bottom blade and wide at both ends in terms of promoting chip separation.

  Here, as the role sharing of the cutting edge related to the cutting at the time of drilling, as shown in FIG. 10, the bottom edge 30 of the first tip 15 is on the bottom side of the end mill with respect to the bottom edge 31 of the second tip 16. Therefore, the first tip 15 contributes to cutting and the second tip 16 does not contribute to cutting on the outer peripheral side of the hole diameter at the time of drilling. On the other hand, since the inner peripheral side of the hole diameter is the cutting edge arrangement of only the second chip 16, the second chip 16 contributes to cutting. In this case, regarding the chip processing on the inner peripheral side of the hole diameter at the time of drilling, a large cutting speed difference occurs at both ends of the chip to be discharged because the cutting speed is very small near the end mill shaft center. Moderately divided chips are discharged.

  Further, in shoulder processing, groove processing, and the like, since the processing form is intermittent processing compared to continuous processing such as drill processing, chip treatment performance is not required and low resistance is required. For this reason, the height of the chip body relative to the seating surface 9 on the upper surface 5 on the rear side of the breaker wall 13a gradually decreases as the distance from the breaker wall 13a increases. The height in the vicinity of the screw hole is set lower than that of the long-side cutting edge 7, and the cutting resistance increase due to contact between the chips and the breaker wall 13a is alleviated. In addition, since the both ends of the breaker wall 13a set higher than the cutting edge for chip processing at the time of drilling are set lower than the vicinity of the center, the chip and the chip body in shoulder processing and groove processing The increase in cutting resistance due to the contact with the upper surface 5 is mitigated.

  As mentioned above, although embodiment of this invention was illustrated, this invention is not limited to the said embodiment, It cannot be overemphasized that it can be made arbitrary, unless it deviates from the objective of invention.

1: Throw away tip 2: Short side surface 3: Long side surface 4: Side surface 5: Top surface 6: Short edge cutting edge 7: Long edge cutting edge 8: Corner cutting edge 9: Seating surface 10: Screw hole 11: Rake face 12: groove bottom face 13: breaker projection 13a: breaker wall 14: end mill body 15: first tip 16: second tip 30: bottom blade 31 of the first tip 31: bottom blade 32 of the second tip : Outer peripheral edge 33 of the first insert: outer peripheral edge h2 of the second insert h1: a step height between the cutting edge height and the breaker wall height in the AA cross section h2: between the cutting edge height and the breaker wall height in the BB cross section Step w1: Breaker width in the AA cross section w2: Breaker width in the BB cross section

Claims (5)

First and second cutting edges provided with a short edge and a long edge on the cross ridge formed by the side surface and the upper surface of the tip body having a polygonal plate shape at the tip of the tool body having a substantially cylindrical shape. The first tip is attached to the tool body with the long side cutting edge as an outer peripheral edge and the short side cutting edge as a bottom edge, and the second tip has the long side cutting edge at the bottom. As a blade, a throwaway end mill attached to the tool body as an outer peripheral blade with the short side cutting edge,
The first tip is provided with a breaker wall on the rake face along the bottom blade, and the bottom blade is gradually recessed toward the center when viewed from the front end surface of the tool body. The thrower end mill is characterized in that the breaker wall has a convex shape that gradually increases from the seating surface of the chip body toward the center thereof.   The center part of the breaker wall is positioned higher than the entire bottom blade in the front end view of the tool body, and both ends of the bottom blade are positioned higher than both ends of the breaker wall. The throw-away end mill according to claim 1, wherein the throw-away end mill is characterized. The throwaway end mill according to claim 1 or 2 , wherein a rake angle at both ends of the bottom blade of the first tip is larger than other portions of the bottom blade. The throwaway end mill according to any one of claims 1 to 3 , wherein a height of the tip main body with respect to a seating surface on a rear side of the breaker wall is gradually reduced as the distance from the breaker wall increases. The first tip is characterized in that, in a side view, the short side cutting edge is an arcuate concave curve, and the long side cutting edge has a constant cutting edge height with respect to the seating surface. The throw-away end mill according to any one of claims 1 to 4 .

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