JPH11813A - Throw-away type end mill and throw-away tip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a throw-away type end mill and a throw-away tip to allow smooth and high efficient working with excellent cutting balance by a tool having both functions of a drill and an end mill. SOLUTION: A side angle cutting edge 9A in a long side of a throw-away tip 7 is arranged as an end cutting edge in the center side of a tool main body 1 to form a central edge 8B, and a side angle cutting edge 9B in a short side of the tip 7 is arranged as an end cutting edge in the periphery of the tool body 1 to form a periphery edge 8A. A tip corner of the central edge 8B is arranged to be coincident with a tip corner of the periphery edge 8A in a rotation locus with an axial center as a center.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away type end mill in which a center blade and an outer peripheral blade are detachably mounted, and a throw-away tip.

[0002]

2. Description of the Related Art Excavation of a die or the like often involves a combination of a punching process and a groove process, and requires a drill or an end mill or a composite tool having both of these functions. The composite tool is a tool that realizes multifunctional machining with one tool without requiring two tools, a drill and an end mill. Conventionally, development of these composite tools has been carried out, and in particular, there is a strong demand in a processing field such as a die.

Accordingly, indexable end mills having various configurations have been developed to realize the above-mentioned multi-functional machining and to satisfy various functions such as balance during machining, machining accuracy and tool life. Has reached.

Conventionally, a throwaway type end mill of this type is disclosed in Japanese Utility Model Laid-Open Publication No. 2-110411,
Japanese Patent Application Laid-Open No. -47810 and JP-A-7-164213 are known.

[0005] Japanese Unexamined Utility Model Publication No. 2-110411 and Japanese Unexamined Patent Publication No. Hei 8-47810 disclose a throw-away tip having the same shape and the same size (hereinafter referred to as "tip").
Are mounted on the center side and the outer peripheral side, and are fixedly fastened by fastening screws which are screwed into screw holes drilled vertically to the chip mounting seat bottom wall. Japanese Patent Application Laid-Open No. 7-164213 is characterized in that a screw hole is formed obliquely with respect to the chip mounting seat bottom wall.

First, Japanese Unexamined Utility Model Publication No. 2-110411 discloses that a first edge is formed on a long edge of a chip upper surface.
Are formed, and a second cutting edge is formed on a side ridge forming a short side. The first cutting edge is an outer cutting edge, and the second cutting edge is a bottom cutting edge. As described above, the tool is mounted on the outer peripheral side of the tool body, and another chip is mounted on the center side of the tool body using the first cutting edge as the bottom blade and the second cutting edge as the outer blade. The positions of the cutting edge tips in the radial direction and the axial direction of the chips on the center side and the outer peripheral side do not coincide in both directions, and are mounted with a step.

[0007] Japanese Patent Application Laid-Open No. 54-99287 discloses a structure in which the cutting edges of the bottom blades of the center side and outer peripheral side chips are formed to be almost equal. As in the prior art, a parallelogram positive type tip is fixed to the tip mounting seat at the tip of the tool body by a screwing method or the like. The chip on the center side has a rake face on a plane including the rotation axis of the tool, the radial rake in the radial direction is 0, and the cutting edge ridge line serving as the bottom blade is at an angle to the perpendicular direction of the tool rotation axis ( Hereinafter, it is referred to as “watermark angle of the bottom blade”) with an inclination of 20 ° to 15 °.

[0008] On the other hand, the chip on the outer peripheral side is incorporated at a position which is substantially axially symmetric about 180 ° in the radial direction with the chip on the center side. The position of the cutting edge in the axial direction coincides with the position of the cutting edge of the central tip. The positions in the radial direction are disposed on different radii, and the cutting diameter is determined by one of the outer peripheral blades.

Japanese Unexamined Patent Publication No. Hei 7-164213 discloses a method in which a pair of parallelogram-shaped throw-away tips is provided in a tip mounting seat at a tip end portion of a tool body. The screw hole is formed so as to be slanted from the bottom wall in the direction of increasing the thickness in the tip end portion of the tool body. The chip is mounted on the bottom wall and is received on the head of a tightening screw which is removably fastened through the mounting hole and on the flat seat surface formed at the open end of the mounting hole. Fixed.

With this configuration, the length of the effective screw portion of the screw hole formed in the bottom wall of the chip mounting seat can be further increased. Also, in the process of tightening the tightening screw into the screw hole via the mounting hole, while proceeding so that the head of the tightening screw pushes the flat seat surface of the mounting hole toward the chip seat bottom wall, The chip is fixed by pressing the lower surface of the chip against the bottom wall and the side surface of the chip against the side wall.

[0011]

The problems of the prior art will be described below.

According to the first prior art, a parallelogram flat plate-like insert having the same shape and the same size is attached to the center of the tip of the tool body and the outer periphery thereof in different directions. Compared to conventional tools with the same length of the cutting edge on the outer peripheral side, the cutting area on the bottom edge can be increased, and the cutting depth on the outer peripheral side can be increased to improve cutting efficiency. I can make it. In addition, by disposing the cutting edge position of the bottom edge on the outer peripheral side to the axial front end side from the cutting edge position of the bottom edge on the center side, the bottom edge on the center side is protected and its loss is prevented beforehand. I can do that.

[0013] However, since the positions of the cutting edges of the bottom blades on the center side and the outer peripheral side are not uniform, in the case of the piercing process by the longitudinal feed, the cutting efficiency is low because substantially one-blade cutting is performed.
Further, the tool body becomes unbalanced, which is not preferable from the viewpoint of machining accuracy and tool life. Since the cutting edge position in the radial direction is not located on the same radius as well, even when performing grooving by lateral feed, the number of effective blades is one, and high efficiency processing cannot be desired. In addition, since the watermark angle of the bottom blade on the center side and the outer peripheral side is set to 0 ° or a minute angle, a large thrust force is applied at the time of piercing processing, so that smooth cutting can be performed. It will be difficult.

In the second prior art, the length of the cutting edge of the bottom blade on the center side and the length of the cutting edge on the outer peripheral side are substantially equal to each other.
Because it is formed with the position of the cutting edge in the axial direction aligned,
At the time of vertical feed, both cutting edges are simultaneously brought into contact with the workpiece to perform machining, and the tool body is machined with good balance.

However, since the positions of the cutting edges in the radial direction on the center side and the outer peripheral side do not exist on the same radius, the cutting edge on the center side is used only at the time of piercing by longitudinal feed. The grooving by traverse feed is a cutting with one effective tooth, and is a cutting with low cutting efficiency.

In the first prior art and the second prior art, since the starting point positions of the tips of the cutting edges are not uniform, the vertical or horizontal feed or the simultaneous vertical and horizontal feed is performed.
The cutting balance of the tool body is poor, making it difficult to maintain accurate machining. If the cutting balance is poor, the tool life may be shortened by inducing vibration or the like. Further, in the case of grooving by traverse feed, since the number of effective blades is one, it is difficult to realize high-efficiency machining.

In the third prior art, a screw hole is formed obliquely from the bottom wall of the tip mounting seat in the direction of increasing the thickness in the tip end portion of the tool body. The length of the effective threaded portion formed in the seat can be further increased, and the adhesion of the throw-away tip to the bottom wall can be ensured.

However, when the head of the screw presses the flat seat surface of the mounting hole at the center of the throw-away tip toward the bottom wall of the tip mounting seat, the contact surface between the screw head and the flat seat surface is Since the bottom of the throw-away tip does not uniformly press against the bottom wall, the seating of the throw-away tip becomes unstable.
In particular, in the case of grooving by transverse feed, there is a danger that the throw-away tip will float or induce chatter vibration because the ratio of the feed force component of the cutting resistance increases.

[0019]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has a tip mounting seat at a position substantially axially symmetric at a tip end portion of a tool main body, and the rotation direction of the tip mounting seat is determined. A screw hole is drilled in the center of the bottom wall that faces, and by tightening a tightening screw that is screwed into the screw hole, a flat throw-away chip placed on the chip mounting seat is formed. In the throw-away type end mill configured to be detachably pressed and fixed through the mounting hole, the throw-away tip mounted on the tip mounting seat has a parallelogram flat plate of the same shape and the same size. A central edge of the tool body as a bottom edge with a side edge cutting edge, which is a long side thereof, as a bottom edge,
In addition, the short edge of the side ridge cutting edge is disposed as a bottom blade on the outer peripheral side of the tool main body to form an outer peripheral edge, and further, the tip corner of the central blade and the outer peripheral edge tip corner are formed by an axis. It is characterized by being arranged so as to coincide with each other in a rotation trajectory centered on the heart.

Further, the throwaway tip is provided with a positive relief angle on a side surface connected to the edge ridge cutting edge sandwiching the acute apex angle of the upper surface of the parallelogram, and has a rotationally symmetric position with respect to the apex angle. A positive relief angle is also given to the side surface connected to the edge ridge cutting edge sandwiching the acute vertex angle of the lower surface in
Further, a mounting hole having a central axis parallel to the opposite side surface is formed in a center portion of the indexable insert.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

In FIGS. 1 to 4, a handle portion is provided axially rearward of a tool main body 1 of a rod-shaped indexable end mill (hereinafter referred to as “end mill”).
Further, from the front end to the rear end, linear chip discharge grooves 2 and 3 are formed at positions substantially symmetric with respect to the axis. These first and second chip discharge grooves 2,
A tip mounting seat 4 is formed at the tip of the tip 3 and is notched in the axial direction and the radial direction in the rotation direction. The tip mounting seat 4 is also used as a center blade 8B and an outer peripheral blade 8A. A throw-away tip (hereinafter, referred to as a “tip”) 7 of the same shape and size is inserted through the mounting hole 5,
It is fastened and fixed by a fastening screw 6.

FIG. 1 is a perspective view of the tip of the tool body 1. FIG. The outer peripheral edge 8A is a short side edge ridge cutting edge 9B.
Is disposed on the outer peripheral side of the tool main body 1 with the long side edge portion cutting edge 9A as an outer blade. The cutting edge length of the outer cutter determines the digging depth, and can be dug deeper according to the length of the cutting edge.

On the other hand, the center blade 8B is disposed on the center side of the tip of the tool body 1 with the long side ridge cutting edge 9A as the bottom blade and the short side ridge cutting edge 9B as the outer blade. The length of the cutting edge of the bottom blade is over-centered beyond the axis o of the tool body 1 so that the piercing process can be performed, and a chamfering blade 17 is formed at a position overlapping the axis o. Thereby, the cutting edge loss at the center portion due to the thrust force is avoided, and the piercing process with high fracture resistance and without a pilot hole becomes possible.

FIG. 2 is a front view of the tip portion of the tool main body 1, and FIG. 3 is a bottom view of FIG. The center blade 8B and the outer peripheral blade 8A are mounted at positions substantially axially symmetric with respect to the axis o of the tool main body 1 in such a manner that both centers are raised. The centering-up is for preventing the rigidity of the tool body 1 from decreasing and preventing the chip flank from interfering with the workpiece.

The cutting edge positions of the center blade 8B and the outer peripheral blade 8A are made coincident with the axial direction of the tool body 1 in order to enable machining in all directions while maintaining the cutting balance. It is located on the radius. That is, the distal end corner of the center blade 8B and the distal end corner of the outer peripheral blade 8A are disposed so as to coincide with each other in a rotation locus about the axis. The watermark angle α of the bottom blade is made in consideration of the balance of the cutting force in the case of lateral feeding, and the outer blade 8A and the center blade 8B have the same angle.

The vertical feed processing is processing by feeding the tool body 1 in the axial direction. If the positions of the cutting edges of the center blade 8B and the outer blade 8A are not uniform, the tool body 1 becomes unbalanced when biting. In some cases, chipping of the cutting edge may occur due to chatter vibration. Therefore, the above-described problem is avoided by matching the positions of the cutting edge tips in the axial direction. On the other hand, the lateral feed processing is processing by feed orthogonal to the axial direction of the tool main body 1. By locating the tip of the cutting edge on the same radius, the tool body 1 is prevented from being unbalanced, and the number of effective blades becomes two, so that the feed amount per rotation is doubled. The cutting efficiency can be improved, and the cutting time can be shortened.

As shown in FIG. 4, the chip 7 has a substantially parallelogram flat plate shape. The flank surfaces connected to the edge ridge cutting edges 9A and 9B sandwiching the acute apex angle of the upper surface 14 are provided with positive clearance angles β and γ, and the lower surface 15 that is rotationally symmetrical to the apex angle. The positive flank angles β and γ are also given to the flank surfaces connected to the side ridge cutting edges 9A and 9B sandwiching the acute vertex. A mounting hole 5 having a central axis parallel to the opposing side surface 16 is formed in the center of the throw-away tip. In addition, chip 7
The upper surface 14 and the lower surface 15 are formed with arc-shaped concave grooves extending along the side edge cutting edges 9A and 9B in order to perform a breaking process of chips flowing out. In addition, even if the groove is not formed, there is no problem in the chip processing. The chip 7 according to the present invention is also applicable to small diameter boring tools.

FIGS. 5 and 6 show the state of the chip mounting seat wall surface according to the conventional product and the product of the present invention, respectively. In both cases, the fastening screws 6, 21 are fastened at a predetermined angle in the direction of increasing the thickness of the tool body 1 with respect to the normal direction of the bottom walls 10A, 23A. The screw holes 13 and 22 are formed obliquely with respect to the bottom walls 10A and 23A,
The effective thread is longer and, as a result, the tightening screws 6, 21
The fitting length can be lengthened. As a result, the tightening force of the tightening screws 6, 21 is increased, so that the loosening of the tightening screws 6, 21 due to vibration during cutting can be prevented, and the tool life can be extended.

The conventional chip mounting seat 25 shown in FIG.
Is composed of a bottom wall 23A and a side wall 23B inclined at an angle larger than 90 ° with respect to the bottom wall 23A. The tip 20 has a head 26 of the tightening screw 21 and a mounting hole 28.
By being pressed at the same time as being received by the flat seating surface 27, it is fixed to both wall surfaces of the bottom wall 23A and the side wall 23B. However, with such a configuration, the tightening screw 21
Of the tip 20 is substantially in contact with the flat seating surface 27 of the mounting hole 28, so that the lower surface of the chip 20 is
3A cannot be pressed uniformly, and in particular, the adhesiveness of the lower surface on the cutting edge side that performs the cutting action becomes insufficient.
In such an unstable state, there is a danger that the tip will float or chatter vibration will be induced to cause a cutting edge defect during the processing in which the ratio of the back force component and the feed force component of the cutting force increases.

The tip mounting seat 4 of the present invention shown in FIG.
It is composed of a bottom wall 10A and side walls 10B inclined at the same angle as the clearance angles β and γ of the chips. Since the mounting hole 5 of the chip 7 is formed such that the play with the tightening screw 6 is very small, the head 11 and the flat seat surface 12 are completely removed in the process of tightening the tightening screw 6. As a result, the lower surface of the chip 7 can be uniformly pressed against the bottom wall 9, and only the adhesion on the cutting edge side does not become insufficient. With such a configuration, the cutting force applied to the cutting edge can be supported by the side wall 10B, and the contact stress between the head 11 and the seat surface 12 of the tightening screw 6 is reduced,
Cracking of the chip 7 during cutting and breakage of the tightening screw 6 are also free from any problem. In particular, in the case of grooving by traverse feed or heavy cutting with a deep cut, the above-described support effect of the side wall 10B becomes remarkable, and highly safe machining that can avoid various troubles can be realized. .

[0032]

According to the present invention, in machining by vertical or horizontal feed or simultaneous vertical and horizontal feed, the cutting action of both the cutting edge on the center side and the outer peripheral side enables stable machining with good cutting balance and high machining accuracy. Can be. In particular, in the case of grooving by lateral feed, the number of cutting edges involved in cutting is two, and high-efficiency machining can be realized. In addition, since the back force component and the feed force component of the cutting resistance are supported on the side wall of the tip mounting seat, trouble does not occur even in heavy cutting with a deep cut.

[Brief description of the drawings]

FIG. 1 is a front end perspective view showing one embodiment of a tool main body according to the present invention.

FIG. 2 is a front view of a tip end portion of the tool main body of FIG. 1;

FIG. 3 is a bottom view of FIG. 2;

4A and 4B show one embodiment of a throw-away tip according to the present invention, wherein FIG. 4A is a plan view and FIG.
FIG. 4C is an enlarged cross-sectional view along the line A, and FIG.
FIG. 3 is an enlarged cross-sectional view along a line.

FIG. 5 is a cross-sectional view illustrating a state of a wall surface of a conventional chip mounting seat.

FIG. 6 is a cross-sectional view illustrating a state of a wall surface of a chip mounting seat according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tool main body 4 Tip mounting seat 5 Mounting hole 6 Tightening screw 7 Indexable insert 8A Peripheral blade 8B Center blade 9A Long side edge cutting edge 9B Short side edge cutting edge 13 Screw hole

Claims (3)

[Claims] 1. A tip mounting seat 4 is provided at a substantially axially symmetric position of a tip end portion of a tool body 1, and a screw hole 13 is formed in a central portion of a bottom wall 10A facing the rotation direction of the tip mounting seat 4. By tightening the tightening screw 6 to be screwed into the screw hole 13, the plate-like throw-away chip 7 mounted on the chip mounting seat 4 can be detachably attached through the mounting hole 5. In the throw-away type end mill configured to be pressed and fixed, the throw-away tip 7 mounted on the tip mounting seat 4 forms a parallelogram flat plate having the same shape and the same size, and has a length equal to the length thereof. The side ridge cutting edge 9A, which is a side, is disposed on the center side of the tool body 1 as a bottom blade to form a center blade 8B, and the short ridge edge cutting edge 9B is a bottom blade. Disposed on the outer peripheral side of the tool body 1 to provide an outer peripheral blade 8A, and the center blade 8B
And a tip corner of the outer peripheral edge 8A is disposed so as to coincide with a rotation locus about an axis. 2. The edge insert cutting edge 9 sandwiching the acute vertex of the upper surface 14 forming a parallelogram.
A positive clearance angle β, γ is given to the side surface 16 connected to A, 9B, and the side surface connected to the side ridge cutting edges 9A, 9B sandwiching the acute apex angle of the lower surface 15 which is rotationally symmetric to the apex angle. 16
Are also provided with positive clearance angles β and γ, respectively, and a mounting hole 5 having a central axis parallel to the opposed side surface 16 is formed in the center of the indexable insert. The throw-away tip according to claim 1, characterized in that: 3. The chamfering blade 17 is formed at a position where the side edge cutting edge 9A serving as the bottom blade of the center blade 8B overlaps with the axis o of the tool body 1. Throwaway tip.