JPH0630334Y2 - Positive throwaway tip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a positive throwaway chip that is detachably attached to the outer peripheral portion of a tool body such as a front slice or a cutter.

[Prior Art] In recent years, of this type of positive throwaway chip (hereinafter abbreviated as "chip"), the outer shape is a rectangular plate, and the upper and lower surfaces thereof are cut into a pair of opposite ridges. Various chips are being developed in which a blade is formed and a rake surface is formed on the side surface of the chip along these cutting edges.

12 to 14 show an example of a conventional chip of this type.

This chip 1 is a plate-like shape whose projected shape in the front view is substantially a rhombus, and cutting edges 3, 3 are formed on a pair of opposing ridge sides of the ridge sides of the upper surface 2. The rake face 5 of each cutting edge 3 is provided on each side surface from each cutting edge 3 to the lower surface 4.
Are formed. Here, the rake face 5 is the cutting edge 3
Is formed by a smooth inclined surface extending from the bottom surface 4 toward the center side. The width dimension between the facing rake surfaces 5 of the chip 1 is constant from the cutting edge tip 6 of the cutting edge 3 to the cutting edge rear edge 7.

Further, cutting edges 8 are formed on a pair of ridges along the side surface adjacent to the side surface on which the rake surfaces 5 and 5 are formed on the lower surface 4. Then, on the side surface extending from each cutting edge 8 to the upper surface 2, a smooth rake face 9 is formed, which is inclined from the cutting edge 8 toward the center side of the upper surface 2. Here, the width dimension between these facing rake faces 9 is also the cutting edge tip 10 of the cutting edge 8.
From the cutting edge to the rear edge 11 of the cutting edge is constant.

Further, in the ridge line portion where the rake surfaces 5 and 5 and the lower surface 4 intersect and the ridge line portion where the rake surfaces 9 and 9 and the upper surface 2 intersect,
Each is chamfered with an arcuate cross section. Further, a mounting hole 12 is formed in the center of the upper surface 2 so as to penetrate toward the lower surface 4.

The conventional chip 1 having the above structure is shown in FIGS.
As shown in FIG. 8, the cutting blades 3 and 8 (for example, the cutting blade 3) are positioned on the outer peripheral portion of the cutter body 13 such as an end mill, and are attached and detached by the mounting bolts 14 inserted into the holes 10. It is freely attached and used.

In this case, in order to improve the cutting performance of the chip 1, as shown in FIGS. 16 to 18, the rake face 5 has a positive rake angle α and the cutting edge 3 has The cutting blade tip 6 and the cutting blade rear end 7 are attached to the cutter body 13 so that they are located on the same circular arc surface 15 centered on the axis X of the cutter body 13.

By the way, the conventional chip 1 described above is
The upper and lower surfaces 2, 4 by rotating 0 ° or turning over
It is economical because it can use four cutting edges 3,3,8,8 in total, and it excels in tool rigidity because the cutting resistance acts between the sides with a large width dimension. It has the advantage that it can also be used.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional chip 1, since the rake surfaces 5 and 9 are formed by the flat inclined surfaces, the above-mentioned cutting performance is improved in order to improve the cutting performance. If the rake angle α is increased, the tip angle β of the cutting edge becomes sharp and the strength of the cutting edge is reduced, which may cause the cutting edges 3 and 8 to be damaged especially during heavy cutting. In addition, since the cutting edges 3 and 8 are formed in a straight line, as shown in FIG.
The radius of gyration at 6 is smaller than the radius of gyration at the cutting edge tips 6 and 10 and the cutting edge rear edges 7 and 11. Therefore, as shown in FIG. 19, the machined surface 18 of the object to be machined 17 is cut into a convex curved surface protruding by a dimension δ in the central portion, and there is a problem that the machining accuracy is poor.

[Object of the Invention] The present invention has been made in view of the above circumstances, and it is possible to obtain both high cutting performance and excellent cutting edge strength, and further to achieve a great improvement in the processing accuracy. It is intended to provide.

[Means for Solving the Problems] In the chip of the present invention, the rake faces along the cutting edges formed on the upper and lower surfaces of the chips have the width dimension between the rake faces at the center of the cutting edge and the cutting edge tip of the cutting edge. And the rear edge of the cutting edge is formed by a convex curved surface that is larger than each width dimension, and the intersection of adjacent rake surfaces has a convex curved shape, and the rake surface of the upper cutting edge and the lower surface intersect. A chamfer is formed on each of the ridge portion and the ridge portion where the rake face of the lower cutting edge intersects with the upper surface, and a sub cutting edge is formed at the tip of the cutting edge where the chamfer surface intersects.

[Embodiment] FIGS. 1 to 8 show an embodiment of the chip of the present invention, in which parts common to those shown in FIGS. 12 to 14 are designated by the same reference numerals. The description is omitted.

1 to 4, in the chip 20, the rake face 22 formed along the cutting edge 21 formed on the upper surface 2 has the width dimension between the rake faces 22 at the cutting edge center 23 of the cutting edge 21. It is formed by a smooth convex curved surface that is larger than each width dimension at the cutting edge tip 24 and the cutting edge rear end 25 of the blade 21.

In addition, a rake face 27 along the cutting edge 26 formed on the lower surface 4
However, a smooth convex curved surface such that the width dimension between the rake faces 27 at the cutting edge center 28 of the cutting edge 26 is larger than the width dimension at the cutting edge tip 29 and the cutting edge rear end 30 of these cutting edges 26, respectively. It is formed by.

Here, the convex curved surface forming the rake surfaces 22 and 27 is the fifth
As shown in FIG. 8 to FIG. 8, when the chip 20 is mounted on the cutter body 13, the cutting blades 21 and 26 extend from the cutting blade tips 24 and 29 to the cutting blade rear ends 25 and 30, respectively. It is desirable to have a shape such that they are located on the same circular arc surface 15 centered on the axis X.

Chamfered portions 41 and 42 are formed at the ridge line portion where the rake faces 22 and 22 of the chip 20 intersect the lower surface 4 and the ridge line portion where the rake faces 27 and 27 intersect the upper surface 2 respectively. As a result, sub cutting edges 43 and 44 are formed at both ends of the cutting edges 21 and 26.

Then, as shown in FIGS. 10 and 11, when the tip 20 is attached to the outer peripheral portion of the front milling cutter 45, its sub cutting edge 43 (44) is orthogonal to the axis of the front slice 45. It will be attached detachably with a corner angle CH °.

In the chip 20 having the above structure, the rake face 2
Since it is formed by convex curved surfaces 2 and 27, as shown in FIG. 7, when it is mounted on the cutter body 13 as in the conventional case, the rake angle α increases from the cutting edge tip to the cutting edge rear edge side. Since the rake angle α is gradually increased and the rake angle α having the same size as that of the conventional one is obtained at the rear end of the cutting edge, a cutting edge angle β ₁ larger than that of the conventional chip 1 can be obtained. For this reason, the strength of the cutting edge can be significantly improved, and thus the cutting edge can be prevented from being damaged or excessively worn.

In addition, the rake faces 22 and 2 formed by the convex curved surface
7, the axial rake angle α changes from approximately 0 ° at the cutting edge tips 24, 29 when biting to the cutting edge rear edges 25, 3
Since it gradually and progressively increases as it goes to 0, the cutting performance becomes progressively and weighted well, and the chip breaking and discharging performance is excellent, and hence chattering and vibration can be prevented. It is also possible to obtain excellent cutting effects such as

Furthermore, the convex curved surface forming the rake faces 22 and 27 is
As shown in FIG. 8, by making the cutting edges 21 and 26 along the same arcuate surface 15 centered on the axis X, the machined surface 32 of the object 31 to be machined with respect to the machined bottom surface 33. Since it can be formed at a right angle, the processing accuracy can be greatly improved.

In addition, when the rake face is configured as a flat surface as in the conventional case, the ridge line between the rake faces becomes a straight line, and the angle between the ridge line and the upper face or the lower face is small, and the tip portion of the cutting edge is easily chipped. However, in the above-mentioned embodiment, since the rake faces 22 and 27 are formed by the convex curved surfaces in the square-shaped tip, and the front and back can be used,
A ridgeline 60 formed by these rake faces 22 and 27 becomes a convex curve. Therefore, since the angle between the upper surface 4 or the lower surface 2 and the ridge line 60 is larger by θ than in the case of the above-mentioned prior art, the cutting edge strength of the cutting edge can be increased, and therefore the cutting edge tip is chipped. Is effectively prevented.

Further, in this tip 20, the chamfered portions 41 and 42 chamfer the ridge line portions other than the cutting edges, so that both ends of the cutting edges 21 and 26 are chamfered to form the sub cutting edges 43 and 44. Therefore, the strength of the corner portion of the chip 20 can be enhanced. Moreover, in the state where it is mounted on the front milling cutter shown in FIG. 10, the auxiliary cutting edges 43 and 44 project toward the tip end side and become orthogonal to the axis, so that the finished surface becomes good.

[Effects of the Invention] As described above, in the chip of the present invention, the rake face along the cutting edges formed on the upper and lower surfaces of the chip has the width dimension between the rake faces at the center of the cutting edge as the cutting edge tip of the cutting edge. It is formed by a convex curved surface that is larger than each width dimension at the rear end of the cutting edge, and the intersection of adjacent rake surfaces has a convex curved shape, and the ridgeline where the rake surface of the upper cutting edge and the lower surface intersect. The chamfered surface is formed on each of the ridges where the rake surface and the upper surface of the cutting edge of the lower surface intersect, and a sub cutting edge is formed at the tip of the cutting edge where the chamfered surface intersects. The ridgeline formed by the rake faces is a convex curve. Therefore, since the angle formed between the ridgeline and the upper surface or the lower surface is large, the cutting edge strength of the cutting edge can be increased, and therefore, there is an effect that chipping of the cutting edge can be prevented as much as possible. It is also possible to obtain the effect that the processing accuracy can be significantly improved.

Moreover, in this tip, since the auxiliary cutting edge is formed at the tip of the cutting edge where the chamfered surface intersects, it is possible to increase the strength of the corner portion of the tip and suppress chipping of the edge of the cutting edge. It can be done and the life of the chip can be greatly improved. In addition, since the auxiliary cutting edge is located on the tip side and is orthogonal to the axis line when attached to the front slice or the like, the finished surface becomes good.

[Brief description of drawings]

1 to 4 show an embodiment of the chip of the present invention. FIG. 1 is a front view, FIG. 2 is a side view taken along line XX of FIG. 1, and FIG. Fig. 4 is a side view taken along the line XI-XI, Fig. 4 is a sectional view taken along the line XII-XII in Fig. 1, and Figs. 5 to 9 show the cutting state when the above tip is mounted on the end mill body. 5, FIG. 5 is a front view, FIG. 6 is a bottom view, FIG. 7 is a side development view, FIG. 8 is an enlarged view of part A of FIG. 6, and FIG.
Enlarged sectional views of the machined surface in the figures, FIG. 10 and FIG.
FIG. 10 is a view showing a state in which the above tip is mounted on a front milling cutter, FIG. 10 is a front view in cross section, FIG. 11 is a view taken along line XIV-XIV in FIG. 10, and FIGS. 12 is a front view, FIG. 13 is a side view taken along line P1-P1 of FIG. 12, and FIG. 14 is P2- of FIG.
15 to 19 show a state in which a conventional positive throw-away tip is mounted on the end mill main body, and FIG. 15 is a front view, FIG. 16 is a bottom view, and FIG. FIG. 18 is a side development view, FIG. 18 is an enlarged view of a portion B in FIG. 16, and FIG. 19 is an enlarged cross-sectional view of the processed surface in FIG. 20 ... Chip (Positive throwaway chip),
2 ... Top surface, 4 ... Bottom surface, 21, 26 ... Cutting edge, 22, 27 ... Rake surface, 24, 29 ... Cutting edge tip, 25, 30 ... Cutting edge rear edge, 23, 28 ... Center of cutting edge, α …… rake angle, β, β ₁ …… cutting edge angle.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-52-13184 (JP, A) Actually opened 62-22014 (JP, U) Actually opened 58-44125 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A diamond-shaped plate having cutting edges formed on a pair of ridges facing each other on an upper surface, and a rake surface inclined toward the center side of the lower surface on a side surface extending from the cutting edges to the lower surface. Cutting edges are formed on a pair of ridge portions that are formed and face each other along the side surface adjacent to the side surface of the lower surface, and the side surfaces extending from the cutting edges to the upper surface face the center side of the upper surface. In a positive throw-away tip in which a sloping rake surface is formed and each cutting edge is positioned so that the cutting edge tip is located at an acute-angled corner portion, the rake surface along the cutting edge is the rake at the center of the cutting edge. The width dimension between the surfaces is formed by a convex curved surface that is larger than the width dimension between each of the rake surfaces at the cutting edge front end and the cutting edge rear end of the cutting edge, and the intersection of adjacent rake surfaces is a convex curve. Shape The chamfered surface is formed on the ridge portion where the rake surface of the cutting edge of the upper surface intersects the lower surface and the ridge portion where the rake surface of the cutting edge of the lower surface intersects the upper surface. A positive throw-away tip, characterized in that a sub cutting edge is formed at the tip of the cutting edge where the surfaces intersect.