JPH1058205A - Throw-away chip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a throw-away chip which can lessen the surface roughness of a finished surface, can raise the feed speed, and allows reuse easily. SOLUTION: At the foremost parts in longitudinal direction of a throw-away chip 1, processing parts 3 having the same shape are furnished to perform a machining process. Each processing part 3 is provided at the foremost with a cutter tip 5 extending in the direction across the width, and a rounded corner part 7 is provided at each end of the cutter tip 5 across the width. A pair of straight portions 9 extending parallel so that the width of the throw-away chip 1 is the same are furnished at each side face extending backward from each corner part 7. That is, the straight portions 9 are positioned parallel with the axis T, i.e., vertically to the cutting edge 5a of the cutter tip 5. A taperd portion 11 is extending from the tail of each straight portion 9 so that the side face part is throttled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away insert which can be used for grooving or the like.

[0002]

2. Description of the Related Art Conventionally, as a throw-away insert for grooving, for example, as shown in FIG. 6 (a), a column-shaped insert having a cutting blade tip P1 at a tip in a processing direction is known. . This type of indexable insert has a corner portion P2 in which both ends in the width direction of the cutting edge P1 are rounded.
The side surface P3 extending rearward from the corner portion P2 is formed in a tapered shape for the purpose of reducing frictional resistance during cutting, and the width of the throw-away tip gradually decreases. I have.

Further, as shown in FIG. 6 (b), both left and right corners P6 of the cutting edge P5 are C-chamfered and cut, and a side surface P7 extending rearward from the corner P6 is formed as described above.
Tapered ones are known.

[0004]

However, when grooving is performed using the above-mentioned indexable insert, there are the following problems, and further improvement is required. No surface roughness The above-mentioned indexable insert has a side surface shape that is tapered inward toward the rear from the rounded corner, so that the side surface of the indexable insert is Therefore, there is a problem that the processed surface (finished surface) of the workpiece is rough (surface roughness is large).

The surface roughness is theoretically obtained by the following equation (1). In the grooving process, the shape of the corner portion of the groove formed in the workpiece is usually the corner portion. In order to prevent breakage due to the concentration of stress of the insert, etc., and also in the case of a throwaway insert, in order to prevent the breakage of the corner of the throwaway insert, the R shape of the corner of the throwaway insert Also have restrictions in advance. Therefore, under this constraint (R = constant), in order to improve the surface roughness (= reduce the value of the surface roughness), the feed speed f must be reduced as is clear from the equation (1). Must.

Surface roughness = f ² / 8R (1) where f: feed amount per rotation (= feed speed) [mm /
rev] R; corner radius [mm] However, when the feed speed f is reduced, the processing speed is reduced and the productivity is deteriorated, and the indexable insert tends to wear quickly (as the feed speed f decreases). Therefore, the feed speed f cannot be reduced so much. That is, when the corner radius R is determined and the feed speed f is defined in a certain range, no surface roughness is obtained as a result.

As is apparent from the above equation (1), increasing the feed rate f increases the surface roughness, and the surface roughness naturally has a required value. However, there is a problem that the feed speed f cannot be increased so much in practice.

Further, re-polishing cannot be performed. Further, for example, in the case of a throw-away tip as shown in FIG. 6 (a), the tip is shaped so as to be wider, so that, for example, the cutting edge at the tip is set in parallel with the tip. ) Even if it is polished and reused, the width of the throw-away tip (and thus the width of the formed groove) is different, and there is a problem that it cannot actually be reused.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a throw-away insert which can reduce the surface roughness of a finished surface, increase the feed rate, and can be easily reused. The purpose is to provide.

[0010]

According to a first aspect of the present invention, there is provided a throwaway insert having a cutting edge at a tip in a processing direction and side portions at both sides in a width direction. On both sides of the cutting edge in the width direction, curved corners connecting the cutting edge and the side are provided, and the throwaways are respectively provided on the side portions extending rearward from the two corners. The gist of the present invention is a throw-away tip characterized in that straight parts are provided so as not to change the width of the tip.

[0011] The corner portion has a round shape which is usually a perfect circle.
Although a shape is adopted, other smooth curved surfaces can also be adopted. According to a second aspect of the invention, there is provided the indexable insert according to the first aspect, wherein a length of the straight portion in a processing direction is in a range of 0.05 to 0.5 mm.

According to a third aspect of the present invention, there is provided the indexable insert according to the first or second aspect, wherein a length of the straight portion in a processing direction is in a range of 0.1 to 0.3 mm. Make a summary. According to a fourth aspect of the present invention, there is provided the indexable insert according to any one of the first to third aspects, wherein the indexable insert is for grooving.

[0013]

According to the first aspect of the present invention, a straight portion that does not change the width of the throw-away tip is provided on the side surface of the throw-away tip. Therefore, at the time of processing, since there is no unevenness on the finished surface due to the presence of the straight portion, the surface roughness of the finished surface is improved.

As is apparent from the above equation (1), if the corner radius R is large, the surface roughness does not increase even if the feed speed f is increased. That is, in the present invention, the presence of the straight portion acts similarly to the case where there is a pseudo large R, so that the feed speed f can be increased without increasing the surface roughness.

Further, in the straight portion, since the width of the throw-away tip is the same, when the tip of the cutting blade is worn out, the tip of the cutting blade is polished again (parallel to the tip) and scraped off. However, the width of the throw-away tip does not change. Therefore, it becomes possible to use the throw-away tip again.

According to the second aspect of the present invention, the length of the straight portion in the processing direction is set in the range of 0.05 to 0.5 mm. In actual processing, if it is within this range,
When used for normal grooving or the like, the surface roughness of the finished surface can be made smaller than before even under the same processing conditions as before.

According to the third aspect of the present invention, the length of the straight portion in the processing direction is set in the range of 0.1 to 0.3 mm. This range is more preferable because it is effective in most ordinary processing using the indexable insert.

According to the fourth aspect of the present invention, it is preferable to use the indexable insert having the above-described configuration for grooving, since excellent grooving of a finished surface can be rapidly performed.

[0019]

Next, an embodiment of a throw-away tip according to the present invention will be described. a) As shown in FIG. 2, the throw-away tip 1 of this embodiment has a columnar shape with a slightly narrow center when viewed from the top (upper side in the figure), and its longitudinal direction (directions of arrows A and B in the figure).
And in the short direction (width direction = arrow C and D directions). The dimensions of the throw-away tip 1 are 20 mm in length in the longitudinal direction, 4.0 mm in length in the width direction, and 8.5 mm in thickness.

At the both ends in the longitudinal direction of the indexable insert chip 1, machining portions 3 of the same shape are provided for cutting, so that if the mounting direction is reversed, which side Cutting such as grooving is also possible. A cutting blade tip 5 extending in the width direction is provided at a tip of the processing portion 3, and both ends of the cutting blade tip 5 in the width direction are subjected to an R process with a radius of 0.4 mm. Corner portions 7 are provided respectively.

In particular, in the throw-away chip 1 of the present embodiment, as shown schematically in FIG. 3 (a), the rear surface of each of the corners 7 (rightward direction in the figure; A pair of straight portions 9 extending in parallel so as to make the width of the throw-away tip 1 the same is provided on each side surface portion 13 extending in the direction (1). That is, the straight portion 9 is formed so as to be parallel to the central axis T (indicated by a dashed line), that is, perpendicular to the cutting edge 5a of the cutting edge portion 5. The length of the straight portion 9 in the processing direction (for example, the direction of arrow A) is 0.3 mm.

Then, from the rear end of each straight portion 9,
The tapered part 11 constituting the side part 13 extends. That is, the tapered portion 11 is formed so that the interval between the both side portions 13 is reduced toward the central axis T, specifically, the taper angle is 2 °. The entire side portion 13 is composed of the straight portion 9, the tapered portion 11, and the constricted portion.

As shown schematically in FIG. 3 (b), the distal end surface 5b of the cutting edge 5 has a taper inclined toward the center by 14 ° downward in the figure. b) The indexable insert 1 having the above-described structure is made of, for example, cermet having high hardness and toughness.

The indexable insert 1 of the present embodiment is characterized by its shape and is not particularly characterized by its manufacturing method. For example, it can be manufactured by the following well-known manufacturing method. For example, the cermet according to the present embodiment uses a TiCN powder, a TiC powder,
iN powder, ZrC powder, TaC powder, WC powder, Mo ₂
A C powder, a Ni powder, and a Co powder are prepared, mixed at a predetermined mixing ratio, wet-pulverized and mixed by a ball mill, dried, and then press-molded at a predetermined pressure to obtain a green compact. Next, this green compact is subjected to predetermined conditions (1400 to 1600).
C.) and polished into a predetermined shape to obtain a throw-away tip 1.

C) When using the throw-away tip 1 of this embodiment, first, as shown in FIG. 4, for example, the throw-away tip 1 is fixed to the tip of the tip holder 21. Specifically, the throw-away tip 1 is fitted into a tip receiving portion 23 provided at the tip of the tip holder 21, and the upper surface 1 a of the throw-away tip 1 is held down by a plate-like presser 25, so that the tip receiving portion 23 and the pressing The throw-away tip 1 is sandwiched between golds 25 and fixed with screws 27.

In this state, as shown in FIG. 5, the throw-away tip 1 together with the tip holder 21 is gradually pushed out in the direction of arrow A toward the rotating workpiece 29.
A grooving process is performed on the (rotating) workpiece 29. Thus, the throw away tip 1 of the present embodiment is
Backward from the R-shaped corner 7 (throwaway tip 1
Straight portion 9 so as not to change the width of
It has.

Therefore, at the time of machining, since the straight portion 9 cuts the unevenness of the finished surface 29a of the workpiece 29,
Even if the feeding speed is not reduced, there is an effect that the surface roughness of the finished surface 29a is reduced. Further, even when the feed rate is increased, a better surface roughness than before can be obtained, so that the feed rate can be increased to improve the productivity. When the feed rate is increased, the wear of the throw-away insert 1 is small even with the same number of processings, so that there is an advantage that the life of the throw-away insert 1 is extended.

Further, in the straight portion 9, the width of the throw-away tip 1 is the same. Therefore, when the cutting edge portion 5 is worn, the cutting edge portion 5 is polished again and scraped off to be thrown away. The away chip 1 can be used again. (Experimental Example 1) Next, a description will be given of an experimental example relating to surface roughness performed to confirm the effect of the present embodiment.

As a throw-away tip used in the experiment, a throw-away tip (sample No. 1) having a straight portion similar to that of the above-described embodiment was used, and as a comparative example, there was no straight portion and an R-shaped corner portion. Using a throw-away tip (sample No. 2) and a throw-away tip (sample No. 3) having no straight portion and a C-chamfered corner, cutting was performed under the following processing conditions. In addition, it was cut by WET at the time of processing.

Workpiece to be cut: alloy steel (JIS SCr420) Cutting speed: 150 m / min Feed rate: 0.12 mm / rev And the surface roughness of the finished surface of the workpiece (10-point average roughness; RZ) Was measured. The results are shown in Table 1 below.

[0031]

[Table 1]

As is clear from Table 1, even under the same cutting conditions, the surface roughness of the present embodiment was as small as 5 μm, and the surface roughness of the comparative example was all suitable. The degree is as large as 9.8 μm or more, which is not preferable. (Experimental Example 2) Next, an experimental example regarding the feed speed which was performed to confirm the effect of the present embodiment will be described.

As a throw-away tip used for the experiment, a throw-away tip (sample No. 4) having a straight portion similar to that of the above-described embodiment was used, and as a comparative example, a straight portion having no straight portion and an R-shaped corner portion was used. A throw-away tip (Sample No. 5) and a throw-away tip (Sample No. 6) having no straight portion and a C-chamfered corner portion were used.

As the workpiece to be cut, alloy steel (JI
(SSCr420) was adopted and cut by WET. Then, the feed speed at the time of cutting was changed in order to obtain the desired surface roughness (10-point average roughness; RZ) of the finished surface of the workpiece. The target surface roughness is 6.0 [μmR
Z] and the feed rate at which the surface roughness is obtained is shown in Table 2 below.
It writes in. The actually obtained surface roughness is also described.

[0035]

[Table 2]

As is clear from Table 2, the target of this embodiment can achieve the target surface roughness even when the feed speed is increased, while the target of the comparative example can achieve the target surface roughness. It can be seen that the feed rate cannot be increased so much in order to do so. (Experimental Example 3) Next, an experimental example regarding the length of the straight portion performed to confirm the effect of the present embodiment will be described.

As the throwaway tip used in the experiment, a throwaway tip (sample Nos. 7 to 12) having a straight portion similar to that of the above-described embodiment was used, and its length was changed. In addition, cutting was performed under the following processing conditions, and at that time, cutting was performed by WET.

Workpiece to be cut; alloy steel (JIS SC
r420) Feeding speed: 0.05 mm / rev Then, the surface roughness (10-point average roughness; RZ) of the finished surface of the workpiece was measured. The results are shown in Table 3 below.

[0039]

[Table 3]

As is clear from Table 3, when the length of the straight portion is longer than the feed speed (feed amount per rotation), the surface roughness is sufficiently small. In addition, as an actual numerical value, it can be seen that when the length of the straight portion is in the range of 0.05 to 0.5 mm, the surface roughness is sufficiently small.
When the length of the straight portion was 0.1 to 0.3 mm, the surface roughness was the best. If the length of the straight portion exceeds 0.3 mm, the surface roughness tends to be rough due to chatter vibration.

It should be noted that the present invention is not limited to the above-described embodiment at all, and it is needless to say that the present invention can be carried out in various modes without departing from the gist of the present invention. (1) For example, not only the corner portion may be a perfect circle R, but also another curved shape may be adopted.

(2) In addition to the cermet, various materials used for the throw-away tip, such as carbide and ceramics, can be used as the material constituting the throw-away tip. (3) Further, a throw-away tip coated with another material can be applied. The indexable insert is made of TiN or TiCN by PVD
, For example, a ceramic such as Si ₃ N ₄ coated with Al ₂ O ₃ , TiN, or TiC by CVD, for example, cermet by PVD
One coated with iN can be used.

[0043]

As described above in detail, in the throw-away tip of the present invention, a straight portion is provided on the side surface of the throw-away tip so as not to change the width of the throw-away tip.

Therefore, during processing, since the straight portion is present, no unevenness is generated on the finished surface, so that the surface roughness of the finished surface is improved. Further, in the present invention, the feed rate can be increased without increasing the surface roughness due to the presence of the straight portion. Therefore, productivity can be improved and the life of the throw-away tip can be extended.

Further, since the width of the throw-away tip is the same in the straight portion, if the tip of the cutting blade is worn, the tip of the cutting blade must be polished again to use the throw-away tip again. Becomes possible.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for explaining an operation of a throw-away tip of the present invention.

FIG. 2 is a perspective view showing a throw-away tip of the embodiment.

FIGS. 3A and 3B schematically show a throw-away tip according to an embodiment, wherein FIG. 3A is an explanatory view showing a part of the plane, and FIG.

FIG. 4 is an explanatory view showing a processing method using the indexable insert of the embodiment.

FIG. 5 is an explanatory view showing a processing state using the indexable insert of the embodiment.

FIG. 6 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Indexable insert 3 ... Processing part 5 ... Cutting edge part 7 ... Corner part 9 ... Straight part 11 ... Tapered part 13 ... Side part

Claims (4)

[Claims] 1. A throwaway tip having a cutting edge at a processing direction end and side surfaces at both sides in a width direction, wherein the cutting edge tip is provided at both sides in the width direction of the cutting edge. And each provided with a curved corner portion connecting the side portion, and a straight portion is provided on each of the side portions extending rearward from the corner portions so as not to change the width of the throw-away tip. A throw-away tip. 2. The length of the straight portion in the processing direction is:
The throw-away tip according to claim 1, wherein the distance is in a range of 0.05 to 0.5 mm. 3. The length of the straight portion in the processing direction is:
The throw-away tip according to claim 1 or 2, wherein the distance is in a range of 0.1 to 0.3 mm. 4. The indexable insert according to claim 1, wherein the indexable insert is for grooving.