JPS5851011A - Step type throwaway cutter - Google Patents

Abstract

PURPOSE:To use eight corners of a throwaway chip, by forming the throwaway chip basically to a square, forming V-shaped grooves in external surfaces of four sides along each side and providing a cutting edge in a corner part of each side. CONSTITUTION:A throwaway chip 1 is formed to basic shape of a square, having a certain thickness t, and a mounting hole 2 is provided in the center of the chip. V-shaped grooves 3, with their center at a half point of the thickness t, are formed along each side in each side face of the chip 1 at a sloped angle alpha. A cutting edge 4, in a length about half the length of each side, is formed in one of the two sides forming corner parts of both upper and lower surfaces of the chip 1. The chip 1 is mounted to a cutter body, and its eight corners can be used under a condition in which an axial rake angle of the cutting edge is determined to a plus direction.

Description

[Detailed Description of the Invention] The present invention relates to a step type indexable cutter,
In particular, the present invention is adapted to a step-type indexable cutter configured to increase the number of corners of the tip by using a specially shaped indexable tip.

Typically, a step-to-pu type indexable cutter is one in which the position of an indexable tip attached to the outer peripheral surface of a cutter body is sequentially shifted in steps in the axial direction and radial direction of the cutter body.

Comparing such a step-type cutter with a normal cutter that is not a step-type cutter (for example, a 7-rice cutter on the front), it is found that the width of the machining allowance is Assuming that d is the feed amount per tooth and f is the feed amount per tooth, chips with a width d will be generated. On the other hand, in the case of a step type cutter, as shown in Figure 2,
'f' is the feed rate per revolution or an integer fraction thereof, and chips divided into d/number of teeth or an integer fraction of the number of teeth are generated.6 As mentioned above, the step type cutter is , when the machining feed rate is constant, ■ the width of the chip is small, ■ f' is the feed rate per revolution (or an integer fraction thereof), and since it is the feed rate per tooth, the chip thickness is small. It is thicker and the specific cutting force is small. Chip pockets can be small because no wide 0-width chips are produced. The number of blades simultaneously involved in C cutting is less than half of the total number of blades, so the total depth of cut is d. /2 or less, and the cutting width on each side is narrow and thick, so the cutting edge is good.

By the way, conventionally known step type cutters include:
For example, as shown in Japanese Utility Model Application Publication No. 51-162388, there is one that uses a square indexable insert and sets the axial rake angle to a positive value in order to reduce the cutting force. . In such a stepped cutter, since the axial rake angle must be set to a positive value, a positive tip must be used, and the usable corners are therefore limited to four. In addition, when the feed rate is small, a cutter with this structure can handle a large depth of cut by setting a large step in the axis and direction, but since the chip thickness is thin in the cutting direction, it is difficult to achieve a large feed rate. It is impossible to expect a significant improvement in machining efficiency.

Further, as another example, as shown in FIGS. 3 and 4, there is also a vertical type using a diamond-shaped tip a. In this case, although there is rigidity, since the axial angle needs to be positive, the usable corners are limited to four, as in the case described above.

As mentioned above, in conventional step type cutters,
Since there is an inconvenience and an uneconomical point in that the number of corners that can be used is four corners at most, this invention is a step type cutter that increases the number of usable corners and has sufficient rigidity by devising the shape of the tip. is intended to provide.

゛Hereinafter, this invention will be explained based on FIGS. 5 to 13.

FIGS. 5 to 7 show an indexable tip 1 to be attached to a cutter according to the present invention. The basic shape of this sub-tube 1 is a square with a constant thickness, and a mounting hole 2 is provided in the center. On each side of the chip 1, a V-shaped groove 3 centered at a point half the thickness 1 is formed along each number with an inclination angle α. Also, the first side of the two sides forming the upper and lower corner portions of the chip 1 is the one on which the cutting edge 4 is formed, having a length of about half of each side.

Next, based on FIGS. 8 to 10, how about the cutter body 5 of the tip 1? Attached state - Explain the problem. Figure 8 shows 10 chips 1m, 1b...-1i,
1j and one wiper chip 1k are shown attached. Each chip la, lb...li, l
j are installed at regular intervals in the rotation direction, and the chips 1
The rotation radius of a is the smallest, and the following chips 1b...
. . . The chips increase in the order of 1i, and the chip 1j is the largest. A wiper tip 1k is installed between the tips 1 and 1j, and its rotation radius is smaller than any other tip. In addition, each chip la, lb...
...The radial rake angles of 1' i and 1 j are set to minus (-8° in the case of the figure), and the radial rake angle of wiper tip 1' is set to be larger than this. (-30° in the figure).

The 7 ace angle θ of each chip 1 above is O as shown in FIG.
It is set at about ~36. In addition, as shown in Fig. 10, the relationship between the relief angle δ in the front direction and the rake angle β in the axial direction is determined so that the relationship is β − α − δ, (α>δ), and the axial Direction (take the angle β to be enriched plus. Also, the first
Figure 1 shows the positional relationship of each side. d in the figure is the depth of cut in the axial direction, and if the depth of cut on each side is Δd, then d=△
dxN (or an integer fraction of xN), where N is the number of blades arranged in the circumferential direction. In addition, 3 in the figure is the depth of cut in the radial direction, and if the depth of cut on each side is Δa, then a=Δax
It is N. Both Δd and Δa are about 0.3 to 1 vote.

Note that the wiper chip 1 may be omitted.

12 and 13 show an example of means for mounting each chip 1, and in FIG.
It is designed to be clamped by. Further, in FIG. 13, the chip 1 is directly fixed using screws 9.

As described above, the step type indexable cutter according to the present invention has a uniquely shaped indexable tip 1 as shown in FIGS. A V-shaped groove 3 is formed along each side, and a cutting edge 4 is provided at the corner of each side, and the cutter body 5 is mounted so that the rake angle β in the axial direction is positive. Because of this, there are effects as listed below.

11) The insert can be used with 8 corners by setting the axial rake angle of the cutting edge to be positive, which is twice as many as before.

(2) The tip receives the main cutting force along the length of one side, so it has high rigidity. Therefore, a large feed per blade can be achieved, and even if the machining allowance is divided, a sufficiently high feed is possible.

(3) Since the chip thickness increases, the specific cutting force decreases.

(4) When the radial rake angle is set to a negative value as in the example, chips are discharged toward the outer circumference, so a large feed is possible even if the chip pocket is small, and it is also possible to form the chip pocket small. The number of blades can be increased by

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the shape processed by a normal cutter, Figure 2
Cross-sectional view of the shape processed by the figure step type cutter, 3rd
The figure is a partial front view of a step-type cutter of the prior art;
The figure is a partially enlarged side view, FIG. 5 is a perspective view of the indexable tip used in the cutter of the present invention, FIG. 6 is a plan view thereof, FIG. 7 is a front view thereof, and FIG. A partially omitted front view of the cutter, Fig. 9 is a partially omitted sectional view, Fig. 10 is a partially omitted side view, Fig. 11 is a sectional view of the processed shape showing the positional relationship of the cutting blades, and Fig. 12 and FIG. 13 are cross-sectional views of an example of how the chip is attached. 1... Chip, 3... Groove, 4... Cutting edge, 5...
Cutter body, k...radial rake angle, β...
Axial rake angle patent applicant Hitachi, Ltd.

Claims (2)

[Claims] (1) In a step-type indexable cutter in which the cutting edge of the indexable tip attached to the outer periphery of the cutter body is shifted in steps in the axial and radial directions,
The basic shape of the above indexable insert is square, and V-shaped grooves are formed along each side on the outer surface of the four sides, and a cutting edge is provided at the corner of each side, and the rake angle in the axial direction of the cutting edge is Step type % type % characterized by being set to positive (2) The step-type indexable cutter according to claim 1, wherein the rake angle in the radial direction of the blade is set to be negative.