JP2001079709A - End mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow thrust-down machining and curved surface machining, to increase the rigidity of an arbor, and to allow stable machining by forming tips into a polygonal shape, and specifying the round shape and thickness of the nose of each corner in an end mill having the tips at the tip section of an end mill body. SOLUTION: A chip pocket 9 is provided at the lower end section of the end mill body 4 of this end mill 1, and polygonal (triangular in figures) tips 8 abuts on the side wall B of the chip pocket 9 and are removably fitted by screws 10. Each tip 8 is provided with a circular arc cutting edge 12 for curved surface machining and a straight-end face cutting edge 11 for thrust-down machining, the round shape of the nose of each corner is set to 2-4, and the thickness is set to 5 mm. The straight cutting edge 11 of each tip 8 applies thrust- down machining to a work while being rotated as an end face cutting edge at the tip of the end mill 1, and the circular arc cutting edge 12 applies curved surface machining to the work while being rotated as an outer periphery circular arc cutting edge.

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 for machining a large projecting portion of a tool.

[0002]

2. Description of the Related Art Conventionally, the machining of dies and the like often involves deep carving on a curved surface, and the amount of protrusion of a tool is large. I was

[0003]

However, the end mill with a round piece tip has a large contact surface with the workpiece, the cutting resistance increases, the machine vibrates, and stable cutting is difficult. For example, a round piece with a nose R = 4 The tip is about 3mm thick and the mounting screw is about 3mm, which is weak in strength.
There is a disadvantage that the chip is easily damaged due to an increase in the cutting resistance. When the end mill is attached to the arbor,
The arbor is weak in rigidity, warps during processing, chatter occurs,
Chip damage was more likely to occur.

[0004] The object of the present invention is the disadvantages of the end mill with a round piece tip as described above, and when the end mill is mounted on an arbor, the arbor is weak in rigidity, flexes during machining, chatters, and damage to the tip. Eliminating the drawback that it was easy to occur, punching down and curved surface processing can be performed at the same time, and the screw for chip mounting is thickened and the thickness is 5 mm.
It is an object to provide an end mill with a tip which is made thicker.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides an end mill body having a circular cutting edge for a curved surface machining of a throw-away type and a straight edge cutting edge for a continuous dropping process. In the end mill provided with a chip having the following characteristics, the chip has a polygonal shape, the nose R of each corner is 2 to 4, and the thickness is 5 mm.

Accordingly, the end mill according to the present invention is provided with an arc cutting edge for curved surface machining and a straight edge cutting edge for punching-down machining, so that each corner of the polygonal insert can be used without using two end mills. Is relatively small as nose R = 2-4, not only the contact area with the work is reduced and cutting resistance is reduced, but also the round piece tip of 3 mm at the center of the polygonal shape.
It can be firmly fixed with a flathead screw or the like that is thicker than about, and the thickness is as thick as about 3 mm to 5 mm, and the rigidity is large, so that stable processing can be performed.

[0007] A plurality of grooves extending in the axial direction are formed on the outer peripheral portion of the arbor to which the end mill main body is attached at equal intervals in the circumferential direction. It is preferable to use an end mill in which the super hard metal is embedded and fixed in the concave groove.

As a result, the stiffness of the arbor is increased, and the arbor bends during processing, no chatter is generated, and damage to the chip does not occur.

Further, a BT to be inserted into the spindle tapered hole
The BT shank taper of the arbor with shank is brought into close contact with the inner peripheral surface of the tapered hole and the flange end of the BT shank is simultaneously brought into close contact with the main shaft surface. In the end mill, a groove is formed in the flange end face of the BT shank, and a collar that engages with the groove is interposed between the flange end face of the BT shank and the spindle end face. An end mill attached to an arbor characterized by being restricted to an end face, providing a counterbore hole in a collar, and fixing the collar to an end face of a flange portion with a bolt or a knock pin.

According to the present invention, in the BT shank of the arbor clamped to the main shaft, the flange constrained to the end surface of the main shaft through the collar, using the outer peripheral surface of the tapered portion closely contacting the inner peripheral surface of the tapered hole as one constraining surface. The end face is used as another constraining surface, and the arbor is constrained by these two surfaces, so that stable machining is possible.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an end mill according to the present invention will be described below with reference to FIGS. The end mill 1 is attached to a tip of an arbor 2 and is mounted on a main shaft 3 of a machine tool via the arbor 2.

A hole 5 for mounting an arbor is formed at the center of the end mill main body 4, and a key groove 6 into which a key 7 is inserted when the end mill 1 is mounted on the arbor 2 is provided at the upper end of the end mill main body 4. A chip pocket 9 is provided at a lower end portion of the end mill body 4, and a polygonal (triangular in this embodiment) indexable insert 8 is brought into contact with a side wall B of the chip pocket 9, and a center of the polygon is formed. A straight portion connecting the arcs of the corners is a straight cutting edge 11 and an arc cutting edge 12 of a nose R = 3 at each corner, and a round piece tip of a nose R = 4 is formed. The thickness is as thick as 5 mm compared to the thickness of about 3 mm, and the strength is increased.

With the above-described structure, the straight cutting edge 11 of the tip 8 attached to the end mill 1 is pushed down on the workpiece while rotating as the end cutting edge at the end of the end mill. On the other hand, the circular cutting edge 12 performs a curved surface processing on the work while rotating as an outer circular cutting edge.

In this curved surface machining, a large cutting resistance acts on the circular cutting edge 12, the nose R of the circular cutting edge 12 is about 2 to 4, and the workpiece is cut at a corner, the cutting resistance is small, and High-speed feeding is also possible because of the strength. On the other hand, a round piece tip used for general roughing curved surface machining also has a minimum nose R = 4, but the same nose R =
Even in the case of 4, since the round piece insert is cut by contacting a part of the circumference with the work, the cutting resistance becomes larger than that of the corner.

In addition, since the insert 8 is of a throw-away type, there are a plurality of cutting edge corners. If the cutting ability of a cutting edge of a certain corner falls, the screw 10 is loosened and changed to a cutting edge of another corner. And the amount of work per chip increases, and chips can be used effectively.

Referring to FIGS. 4 and 5, another embodiment of the present invention will be described. In this embodiment, in order to increase the rigidity of the arbor 2 on which the end mill 1 is mounted, a plurality of hard metal bars 16 extending in the axial direction are provided on the outer peripheral portion of the arbor 15. By providing a plurality of carbide bars 16 in the arbor 2 in this manner, the stiffness of the arbor 2 is improved, bending and chattering during cutting are suppressed, and cutting can be performed more smoothly.

As shown in FIG. 5, a plurality of (three in this embodiment) rectangular cross-sectional grooves 17 having a rectangular cross section are formed in the outer peripheral portion of the arbor 15 at equal intervals in the circumferential direction as shown in FIG. If the hard metal bar 16 is fitted over the entire length of the concave groove 17 and brazed, and its outer surface is fixed so as to slightly protrude from the outer peripheral surface of the arbor 2 over its entire length, the anisotropic field rigidity is improved. Can be increased. Here, the cross-sectional shape of the plurality of carbide rods 16 is rectangular, but the present invention is not limited to this, and the same effect can be obtained by forming a band, a round bar, or a triangle.

Still another embodiment will be described with reference to FIGS. In this embodiment, the end mill is mounted on an arbor with a BT shank.
The tapered portion 22 of the BT shank 21 of the arbor is inserted into the hole 0 so that the inner peripheral surface of the tapered hole 20 and the outer peripheral surface of the tapered portion 22 come into close contact with each other. A groove 25 is formed at the end 24 of the flange 23 of the BT shank 21 so as to go around the tapered portion 22. The end face C of the main shaft 3 faces parallel to the end face D of the flange end 24.

A collar 26 and a collar 27 are mounted in the gap between the end face C of the main shaft 3 and the end face D of the flange end 24. As shown in FIGS. 7 and 8, the collars 26 and 27 are obtained by symmetrically dividing a ring-shaped collar into halves. The outer diameter of the flange end 24 is substantially the same as that of the end face D, and the inner diameter is slightly increased. I have. Further, on the inner peripheral side, projections 28 and 29 that engage with the groove 25 provided on the flange end 24 and a bolt 30 for fixing to the end face D of the flange end 24 during assembly and a counterbore 31 for using a knock are provided. Each is provided.

As described above, the projections 28 of the collars 26 and 27
Since the main shaft 3 rotates at a high speed because the shafts 29 and 29 are engaged with the groove 25, even if the centrifugal force increases, the protrusions 28 and 29 and the side surfaces of the groove 25 come into close contact with each other and do not come off.
Also, since the collars 26 and 27 are attached to the end face D of the flange end 24 with bolts or knock pins 31, even when the tool is replaced, the collar 2 can be moved from the end face D of the flange end 24.
6 and 27 do not come off.

As described above, the BT shank 21 attached to the arbor inserted into the main shaft 3 is configured such that the outer peripheral surface of the tapered portion 22 which is in close contact with the inner peripheral surface of the tapered hole 20 is the first constraining surface.
Since it is constrained by the two surfaces serving as the second constraining surfaces to be in close contact with the spindle end face C via the collars 26 and 27, high support rigidity can be maintained even in roughing cutting and high-speed rotation cutting.

[0022]

As described above, according to the present invention, the tool can be replaced even in the conventional processing using two types of end mill dedicated to punching-down processing and end mill with round piece insert dedicated to curved surface processing. There is no necessity, and it is possible to push down and curve the surface, increase the rigidity of the arbor, and even if the arbor has a BT shank,
Stable processing became possible by restricting two surfaces.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an end mill showing one embodiment of the present invention, and a side view thereof.

FIG. 2 is an explanatory view of an end mill showing one embodiment of the present invention, and is a cross-sectional view taken along line AA of FIG.

FIG. 3 is an explanatory view of an end mill showing one embodiment of the present invention, and is a front view of FIG. 1;

FIG. 4 is an explanatory view of an end mill showing another embodiment of the present invention, and is a side view of the end mill having an increased arbor rigidity.

FIG. 5 is an explanatory view of an end mill showing another embodiment of the present invention, and is a cross-sectional view of an arbor.

FIG. 6 is an explanatory view of an end mill showing still another embodiment of the present invention, in which an arbor with a BT shank is restrained on two sides.

FIG. 7 is an explanatory view of an end mill showing still another embodiment of the present invention, and is a cross-sectional view taken along the line EE of FIG. 6;

FIG. 8 is an explanatory view of an end mill showing still another embodiment of the present invention, and is a detailed view of an “A” part of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 End mill 2, 15 Arbor 3 Spindle 4 End mill main body 5 Arbor mounting hole 6 Keyway 7 Key 8 Chip 9 Chip pocket 10 Screw 11 Straight cutting edge 12 Arc cutting edge 16 Carbide metal 17 Depressed groove 20 Tapered hole 21 BT Shank 22 Taper 23 Flange 24 Flange end 25 Groove 26, 27 Collar 28, 29 Projection 30 Bolt 31 Counterbore

Claims (4)

[Claims] 1. An end mill provided with a tip having an arc cutting edge for a curved surface machining of a throw-away type and a straight end face cutting edge for a punching-down process at a tip end portion of a body of the end mill, wherein the tip is a polygon. The shape is such that the nose R of each corner is 2 to 4 and the thickness is 5 mm.
An end mill characterized by the following. 2. The end mill according to claim 1, wherein a super hard metal is fixed to an outer peripheral portion of an arbor to which the end mill main body is attached along an axial direction thereof. 3. The arbor according to claim 1, wherein a plurality of grooves extending in an axial direction are formed at equal intervals in a circumferential direction on an outer peripheral portion of the arbor, and the hard metal is buried and fixed in the grooves. End mill as described. 4. The BT shank tapered portion of the arbor with a BT shank to be inserted into the main shaft tapered hole is simultaneously brought into close contact with the inner peripheral surface of the tapered hole and the flange end surface of the BT shank is brought into close contact with the main shaft end surface. In an end mill attached to an arbor constrained by two flange end faces, a groove is formed in the flange end face of the BT shank, and the groove is engaged between the flange end face of the BT shank and the spindle end face. A collar to be interposed, the flange end face is restrained by the spindle end face via the collar, and a counterbore hole is provided in the collar, and the collar is fixed to the flange end face by a bolt or a knock pin. End mill mounted on arbor.