JP3383503B2 - Cutting insert - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting insert particularly suitable for cutting an outer periphery of a shaft. 2. Description of the Related Art When machining the outer periphery of a shaft, as shown in FIG. 4, the center of one end face of a shaft S is brought into point contact with the point of a rotation center H, and the other end is connected. Cutting is performed while rotating the shaft S while being held by the chuck C of the lathe. Usually, a cutting insert 10 having a rhombic plate shape and a small nose angle is used, and the cutting insert 10 is fixed to a dedicated holder in a state of being inclined obliquely. This is to prevent the front cutting edge 13 of the insert 10 from contacting the shaft end H1 of the rotation center H when the cutting insert 10 is brought into contact with the peripheral surface of the shaft S. [0004] In many cases, the shape of the shaft S to be processed has several steps D as shown in FIG. When the cutting insert 10 is to be cut with a medium cutting depth, the cutting insert 10 is used in which the width of the breaker groove in the nose portion is made larger and the position of the breaker projection is slightly separated from the tip of the cutting blade. Can be The reason for this is that if the breaker projection is brought closer to the tip of the cutting blade than necessary, the cutting resistance increases, which may cause wear or loss of the breaker projection. [0006] However, even if the breaker projections are arranged on the rear side as described above, when the shaft S as shown in FIG. 5 is machined, there are the following problems. That is, when the step portion D of the shaft S is machined, a slight R
Although the surface remains, when the processing direction is changed from the horizontal direction to the vertical direction or vice versa, the cutting depth temporarily increases. For this reason, the chips may be discharged while being extended without being bent by the breaker projections.
Then, there is a fear that the discharged chips may be entangled with the rotation center H to interrupt the work, or may be entangled with the cutting edge to cause a cutting edge defect. SUMMARY OF THE INVENTION In view of the above-mentioned problems in the prior art, the present invention relates to a cutting insert particularly suitable for cutting the outer periphery of a shaft. Even so, an object of the present invention is to provide a cutting insert capable of reliably curling chips and discharging the chips stably. In order to solve the above-mentioned problems, a cutting insert according to the present invention has a cutting edge formed on a ridge between a rake face and a flank, and a nose portion for cutting chips. In the cutting insert formed with the breaker groove, the breaker wall and the breaker projection,
Behind the breaker protrusion of about 4 mm, a dimple is formed that terminates continuously from the upper edge of the breaker wall to halfway in the height direction of the breaker wall, and has a pointed front end and a rear end. It is characterized by. In the cutting insert of the present invention, the breaker projection is separated from the tip of the cutting blade in order to cope with a moderate cutting amount. Usually, chips are applied to the breaker projection to curl the chip. Prevents entanglement of chips. [0010] In addition, when the depth of cut is sharply increased, such as when processing a stepped portion, chips in a portion that does not hit the breaker projection are bent by wide dimples disposed behind the breaker projection, and the entire chip is cut. The sheet is reliably curled and discharged. As a method of processing chips when the cutting amount is increased, it is conceivable to form a second breaker projection at an appropriate position. However, in this case, the chips hit the convex surface and the cutting resistance increases. In addition, the magnitude and direction of the force applied to the chips on the low cutting side and the high cutting side tend to be unbalanced. On the other hand, when a wide dimple is formed as described above, the magnitude and direction of the force applied to the chips on the low-cut side and the high-cut side are well balanced, and the chip discharge direction is particularly stable. An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 3 show a cutting insert I according to the present embodiment. This cutting insert I is particularly suitable for machining the outer periphery of a shaft, and its overall shape is such that the nose portion 4 has a small cutting edge angle. It has a rhombic plate shape,
A cutting edge 3 is formed on a ridge between the rake face 1 and the flank 2. The nose portion 4 has a breaker groove 6 continuous with the cutting edge 5 and a breaker projection 8 and a breaker wall continuous with the seating surface. As shown in the enlarged view of FIG. 3, the cutting insert I has a breaker projection separated from the tip of the cutting blade in order to cope with a moderate cutting depth. This is curled to prevent entanglement of chips. The cutting insert I is located on the rear side of the breaker projection 8 and inside the cutting edges 3 and 3 at a line symmetrical position (with respect to the bisector of the nose portion 4) at the upper edge of the breaker wall. , A pair of wide dimples 9, 9, which are continuously terminated to the middle of the breaker wall in the height direction, and whose front and rear ends are pointed, are formed at line-symmetric positions. It is preferable that the distance d from the cutting edge 5 to the dimple 9 is in the range of 1 mm to 4 mm, and the width W of the dimples 9, 9 is in the range of 0.5 mm to 4 mm. The cutting insert I constructed as described above is provided with a breaker projection 8 so as to cope with a moderate cutting depth.
The chip is separated from the cutting edge 5, and the chip is normally applied to the breaker projection 8 to curl the chip to prevent the chip from being entangled. In the case where the depth of cut is sharply increased, for example, when processing a stepped portion, chips in a portion that does not hit the breaker projection 8 are bent by the wide dimple 9 disposed behind the breaker projection 8, The entire chip is reliably curled and discharged. That is, when the wide dimple 9 is formed as described above, the balance of the magnitude and direction of the force applied to the chips on the low cut side and the high cut side is improved,
In particular, the chip discharge direction is stabilized. When the distance d from the cutting edge 5 to the dimple 9 is smaller than 1 mm, or when the width W of the dimples 9 is smaller than 0.5 mm, the chips sink into the dimples 9. It is difficult, and there is a possibility that the chips are discharged without being curled and extended, or the cutting resistance increases. On the other hand, when the distance d from the cutting edge 5 to the dimple 9 is larger than 4 mm, or when the width W is 4 m
If it is larger than m, the direction in which the chips are discharged may be unstable. Further, the present invention is not limited to the above-described embodiment, and may be in any form without departing from the object of the invention. In the cutting insert I shown in FIGS. 1 to 3, the distance d from the tip 5 of the cutting blade to the dimple 9 is shown.
A cutting insert I having the width W of the dimple 9 as shown in Table 1 was prepared (samples # 1 and # 2), a processing test was performed under the following cutting conditions, and the result was evaluated with the naked eye.
Table 1 shows the results. Cutting conditions V = 150 m / min d = 1-4 mm (variable) f = 0.3 mm / rev. Work material: SCM415 Tool shape: DNMG150412 Cutting fluid: Available [Table 1] As a comparative example, the distance d from the cutting edge 5 to the dimple 9 and the width of the dimple 9
Using cutting inserts as shown in Table 1 (sample # 3 ~
4) The same processing test was performed. As is clear from Table 1, the products of the examples were all better than the products of the comparative examples. As described above, the cutting insert of the present invention is usually used when cutting a chip to a breaker projection to curl the chip to prevent entanglement of the chip and to sharply cut a step. If the cutting depth increases, the chips that do not hit the breaker projections are located behind the breaker projections.
The tip ends continuously from the upper edge of the breaker wall to the middle of the breaker wall in the height direction, and the front end and the rear end are bent with pointed dimples. Since the balance of the magnitude and direction of the force applied to the chips is good, the whole chip is reliably curled and discharged.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top view of a cutting insert according to the present invention. FIG. 2 is a side view of the cutting insert of FIG. 1; FIG. 3 is an enlarged view of a region A in FIG. 1; FIG. 4 is a schematic view showing a method for cutting a shaft. FIG. 5 is a schematic view showing a mode of cutting a shaft having a step portion. [Description of Signs] I Cutting insert 1 Rake surface 2 Flank 3 Cutting edge 4 Nose portion 5 Cutting edge 6 Breaker groove 6a Flat surface 7 Seating surface 8 Breaker protrusion 9 Dimple W width

Claims (1)

(1) A cutting edge is formed at a ridge between a rake face and a flank, and a breaker groove, a breaker wall, and a breaker projection for chip processing are formed at a nose portion. In the cutting insert made, behind the breaker projection 1 to 4 mm away from the tip of the cutting blade, continuously terminates from the upper edge of the breaker wall to halfway in the height direction of the breaker wall, and the front end A cutting insert characterized by forming a dimple having a pointed rear end.