JPH0618734Y2 - End mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an end mill in which a disc-shaped throwaway tip is attached to the tip of a tool body.

[Prior Art] Conventionally, as an end mill of this type, FIGS.
The one shown in the figure is known (for example, the actual exploitation Sho 59-9).
3813). In the end mills shown in these drawings, a tip 3 of a cutting blade 2 of a disc-shaped throwaway tip 1 is attached at a position eccentric from a rotation axis 5 of a tool body 4 by H and h. The cutting blade 2 is attached to the tool body 4 such that the outer side from the tip 3 is positioned in the counter-rotational direction as it goes in the radial direction.

Further, as another end mill, one shown in FIGS. 8 to 9 is known (for example, actual development 58-84809).
Gazette). In the end mills shown in these figures, the tip 13 of the cutting blade 12 of the disc-shaped throwaway tip 11 is mounted at a position eccentric from the rotation axis 15 of the tool body 14 by K. The part is located near the axis of rotation 15.

[Problems to be solved by the invention] Therefore, in the end mills shown in FIGS. 5 to 7, it is not possible to perform cutting from the tip 3 of the cutting edge 2 to the portion from the rotation axis 5 and to make a hole. There is a problem.

Further, in the end mill shown in FIGS. 8 to 9, it is possible to cut even from the tip 13 of the cutting edge 12 to the portion from the rotation axis 15, but it is more h
There is a problem that the thickness of the base metal 16 on which the slow-away chip 11 is mounted is reduced by that much, and the strength of the base metal 16 is reduced.

The present invention aims to solve the above problems.

[Means for Solving the Problems] The present invention has been made in order to achieve the above-mentioned object, and the rake face of the throwaway chip is formed in a convex shape toward the attachment hole, and the throwaway face is seen in the end view. The tip of the cutting edge of the chip is eccentric from the rotation axis of the tool body by a predetermined dimension, and the cutting edge on the rotation axis side from the tip of the cutting edge passes near the rotation axis so that the throw-away tip Further, the throw-away tip is provided so that at least the cutting edge outside the tip of the cutting edge is positioned in the counter-rotational direction as it goes from the rotation axis toward the radial direction.

[Operation] In the present invention, the cutting reaction force generated from the tip of the cutting edge to the cutting edge on the rotation axis side is divided into a tangential component of the cutting edge and a normal component of the cutting edge. Therefore, the component force in the normal direction that affects the damage of the cutting edge becomes smaller than the cutting reaction force. Furthermore, at least the outer cutting edge from the tip of the cutting edge is positioned in the counter-rotational direction from the rotation axis toward the radial direction, so that the outer cutting edge does not contact the work material at the same time, The work material gradually contacts the outside from the tip of the cutting edge. At this time, the chips move in a direction in which the chips escape to the outside from the tip. Further, since the rake face of the throwaway chip is formed in a convex shape toward the mounting hole, the height from the lower surface of the throwaway chip to the vicinity of the mounting hole of the rake face is set in the mounting hole with a screw head. The height from the lower surface to the cutting edge can be lowered even if the height is high enough to lock the portion.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS.

In FIGS. 1 to 3, reference numeral 31 is a tool body formed in a columnar shape, and a base metal 3 is attached to the tip of the tool body 31.
2 is formed. A chip mounting seat 32a having an axial rake angle θ is formed on the base metal 32, and a throwaway chip 33 is mounted on the chip mounting seat 32a. A screw hole 32b is formed in the chip mounting seat 32a, and a screw 34 is screwed into the screw hole 32b. The throw-away chip 33 is formed in a disc shape, and has a mounting hole 33a formed in the center thereof so that the head portion 34a of the screw 34 is locked. Further, the throw-away chip 33 has a flat lower surface that is in close contact with the chip mounting seat 32a, and a rake surface of the upper surface that is convexly curved toward the mounting hole 33a. Further, in the throw-away chip 33, as shown in FIG. 1 and FIG.
5 is fixed at a position shifted by the dimension S with respect to 5, and a part of the cutting edge 33b on the side of the rotation axis 35 from the tip 33c of the cutting edge 33b passes near the rotation axis 35 in the front end view. It is provided in. In this case, as shown in FIG. 3, the cutting blade 33b moves from the rotation axis 35 to the chip mounting seat 32a.
And the rake face in the vicinity of the mounting hole 33a slightly projects from the rotation axis 35 to the side opposite to the chip mounting seat 32a side. Further, as shown in FIG. 2, the tip-side cutting blade 33b is located in the counter-rotational direction from the rotational axis 35 toward the radial direction because the chip mounting seat 32a is inclined at the axial rake angle θ. Is being done.

In the end mill configured as described above, the cutting edge 3
The cutting reaction force F1 generated from the tip 33c of 3b to the cutting edge 33b on the rotary shaft center 35 side is a tangential component force F2 of the cutting edge 33b.
And the component force F3 in the normal direction, the component force F3 in the normal direction affecting damage to the cutting edge is the cutting reaction force F.
It becomes smaller than 1. Further, the cutting edge 33b has a rotation axis 35.
Since the cutting edge 33b does not contact the work material at the same time because it is located in the counter-rotational direction from the cutting edge 33b in the radial direction, the work material gradually contacts from the inside to the outside of the cutting edge 33b. . At this time, the chips move in a direction in which they are escaped from the tip 33c to the outside.

According to the end mill configured as described above, the cutting edge 33
Since a part of the cutting edge 33b on the rotation axis 35 side from the tip 33c of b passes slightly on the chip mounting seat 32a side of the rotation axis 35, it is possible to cut with the cutting edge 33b on the rotation axis 35 side. However, there is an advantage that it can be drilled. Further, the cutting reaction force F1 generated from the tip 33c of the cutting edge 33 to the cutting edge 33b on the side of the rotation axis 35 is large because the cutting speed is slow, but the component force F3 in the normal direction generated on the cutting edge 33b is Since it is smaller than the cutting reaction force F1, the cutting edge 33
It is effective in preventing damage to b. Furthermore, the cutting edge 33
Since b comes into contact with the work material from the inner cutting edge 33b and gradually comes into contact with the outer cutting edge with respect to the work material, it is possible to perform smooth cutting and reduce the cutting resistance. Moreover, since the chips move in a direction in which they are released from the inside to the outside, the chip discharging property is extremely good. Further, since the rake face of the throw-away chip 33 is formed in a convex shape toward the attachment hole 33a, even if the thickness of the attachment hole 33a is the same as that of the conventional throw-away chip, the lower face The height from the cutting edge 33b to the cutting edge 33b becomes lower than the conventional one. For this reason, the chip mounting seat 33b can be brought closer to the rotation axis 35 side by the amount of the reduced height, and the thickness of the base metal 32 can be increased and the strength of the base metal 32 can be improved. Further, in the case of the chip mounting seat having the axial rake angle, the axial rake angle can be increased by the thickness of the base metal 32 as described above. For this reason, in the conventional case, it is difficult to use a throwaway chip having a chip clearance angle of 15 ° or more because the thickness of the base metal becomes thin as the axial rake angle increases, but in the case of the present embodiment. Can be attached with a large axial rake angle even for a throwaway chip having a chip clearance angle of 15 ° to 30 °. Therefore, the cutting resistance can be reduced as compared with the conventional case.

In the above embodiment, the chip mounting seat 32a is formed so as to have the axial rake angle θ, so that the cutting edge 33b is located in the counter-rotational direction from the rotational axis 35 toward the radial direction. The tip mounting seat may be tilted in the counter-rotational direction with respect to the radial direction from the rotation axis 35 so that the cutting edge 33b is positioned in the counter-rotational direction as it goes in the radial direction.

Further, the throwaway chip 33 is formed such that its rake surface has a convex curved surface shape toward the mounting hole 33a. However, this rake surface is formed in a flat shape around the mounting hole 33a, It may be linearly erected from the cutting edge 33b to be formed in a convex shape, or may be formed in a convex shape from a position inside the cutting edge 33b by a predetermined dimension toward the mounting hole 33a.

FIG. 4 is a view showing another end mill, in which the throwaway tip 33 is a cutting blade 3 passing near the rotation axis 35.
3b is slightly displaced from the rotary shaft center 35 toward the chip mounting seat 32a side, and the protruding rake face is mounted so as to contact the rotary shaft center 35.

[Effects of the Invention] As described above, according to the present invention, a part of the cutting edge on the side of the rotation axis from the tip of the cutting edge passes near the rotation axis.
There is an advantage that cutting can be performed at the rotating shaft center portion and drilling can be performed. Further, the cutting reaction force generated from the tip of the cutting edge to the cutting edge on the rotation axis side is large because the cutting speed is slow, but the component force in the normal direction which affects the damage of the cutting edge is larger than the cutting reaction force. Since it becomes smaller, it is effective in preventing damage to the cutting edge. Further, at least the cutting edge outside the tip of the cutting edge is in contact with the work piece gradually from the tip of the cutting edge to the outside, so that the cutting can be performed smoothly and the cutting resistance is reduced. Moreover, since the chips move in a direction in which the chips escape to the outside from the tip, the chip discharge property is extremely good. Moreover, since the rake face of the throwaway chip is formed in a convex shape toward the mounting hole, even if the thickness of the mounting hole is the same as that of the conventional throwaway chip, the cutting edge is cut from the bottom surface. Height is lower than the conventional one. For this reason, the chip mounting seat can be brought closer to the rotation axis side by the amount that the height is lowered, and the thickness of the base metal can be increased and the strength of the base metal can be improved. Further, in the case of the chip mounting seat having the axial rake angle, there is an advantage that the axial rake angle can be increased by the increase in the thickness of the base metal as described above.

[Brief description of drawings]

1 to 3 are views showing an embodiment of the present invention. FIG. 1 is a front view of an end mill, FIG. 2 is a front end view of the end mill, and FIG. 3 is a cross-sectional view of a main part of the end mill. FIGS. 4 and 5 are sectional views of an essential part showing an end mill of another embodiment of the present invention, FIGS. 5 to 7 are views showing a conventional example, and FIG. 5 is a front view of the end mill. FIG. 6 is a right side view of the end mill, FIG. 7 is a bottom view of the end mill, FIGS. 8 to 9 are views showing other conventional examples, and FIG. 8 is a front view of the end mill. FIG. 9 is a left side view of the end mill. 31 ... Tool body, 32 ... Base metal, 32a ... Chip mounting seat, 33 ... Throwaway chip, 33a ... Mounting hole, 33b ... Cutting edge, 33c ... Tip, 34 ... Screw,
35 ... Rotation axis, S ... predetermined size.

Claims (1)

[Scope of utility model registration request] 1. A disc-shaped throwaway chip is mounted on a chip mounting seat of a base metal formed at the tip of a cylindrical tool body, and the throwaway chip has a mounting hole formed at the center thereof. In the end mill fixed to the chip mounting seat with a screw, the throw-away chip is formed so that its rake face is convex toward the mounting hole,
The tip of the cutting blade of the throw-away chip is eccentric by a predetermined dimension from the rotation axis of the tool body in a front end view, and the cutting edge on the rotation axis side from the tip of the cutting edge has the rotation axis center of the rotation axis. An end mill provided so as to pass through the vicinity thereof, and at least a cutting blade outside a tip of the cutting blade is provided so as to be positioned in a counter-rotational direction from a rotational axis toward a radial direction.