JPH04304918A - End mill - Google Patents

Abstract

PURPOSE:To obtain an end mill cutting a high hardness material of HRC 60-70 with excellent efficiency. CONSTITUTION:A rake angle in the diameter direction of an outer peripheral tooth 5 is set in the range of -10 deg.--19 deg. 30' and a relief angle in the range of 15 deg.-23 deg. and a warp angle phi in the range of 35 deg.-45 deg. in the end mill that the outer peripheral tooth 5 is integrally formed with a tool main body 1. A sintered hard alloy equivalent to JIS classification K kind 03-05 is used as the material of the tool main body 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end mill equipped with a spiral peripheral cutting edge, and more particularly to an end mill capable of cutting hardened materials of high hardness.

0002

[Prior Art] Conventionally, high hardness areas (HR), such as molds, etc.
It shall be about C60 to 70. ) The machining of workpieces that have been quenched to a level of There are also attempts to do so. In end mills used for such purposes, for example, the blade part is formed to have a regular hexagonal cross section, and the cross-sectional area of the blade part is increased by making the radial rake angle of the peripheral cutting edge a negative angle. Tools that are designed to increase tool rigidity as much as possible are provided, and in this case, the radial rake angle of the peripheral cutting edge is usually set to a negative angle exceeding -20°.

0003

[Problems to be Solved by the Invention] However, in such end mills, if the radial rake angle of the peripheral blade is set too large to the negative angle side, the sharpness of the peripheral blade will deteriorate significantly and excessive cutting resistance will be added. , the end mill tilts more during machining. On the other hand, if the radial rake angle of the outer peripheral cutter is set too small, the rigidity near the outer peripheral cutter will be significantly reduced, making chatter vibration more likely to occur, and the outer peripheral cutter will be more likely to chip or fall off. If the peripheral blade falls off, it is no longer possible to continue smooth cutting. This invention was made against this background, and an object thereof is to provide an end mill that can ensure the strength of the peripheral blade without excessively deteriorating the sharpness of the peripheral blade and can smoothly cut high-hardness materials. do.

0004

[Means for Solving the Problems] In order to solve the above problems, the inventor prepared a plurality of end mills with slightly different radial rake angles in order to find the appropriate range of the radial rake angle of the peripheral cutting edge, and etc. were investigated. The results are shown in Table 1.

[0005]

[Table 1]

[0006] From these results, we have found a range of radial rake angle of -10° to -19° 30' that can strengthen the cutting edge without excessively impairing the sharpness of the peripheral cutting edge, and furthermore, we have found a range of -10° to -19° 30' that does not impair this effect. As shown, the clearance angle of the peripheral cutter is in the range of 15° to 23°, and the torsion angle is 3.
The angle is set in the range of 5° to 45°, and a cemented carbide corresponding to JIS classification K class 03 to 05 is used as the material of the tool body.

[0007]

[Function] According to the above structure, since the radial rake angle of the peripheral cutting edge is a negative angle smaller than the conventional -20°, the cutting edge of the peripheral cutting edge is high. Further, since the clearance angle is set to 15° to 23°, early wear of the peripheral blade due to insufficient clearance angle is suppressed, and a sufficient cutting edge angle of the peripheral blade is ensured to prevent chipping of the peripheral blade. Furthermore, the twist angle is 3
Since the angle is set in the range of 5° to 45°, the peripheral cutting edge will reliably bite into the workpiece.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIGS. 1 to 4, reference numeral 1 indicates a tool body. This tool body 1 is JIS classification K type 03 to 05 (JIS
It is made of cemented carbide corresponding to B 4053) in a cylindrical shape, and consists of a shank 2 located on the rear end side in the axial direction and a blade portion 3 located on the front end side in the axial direction. The shank 2 is for holding the end mill by a machine main shaft (not shown).

As shown in FIGS. 1 and 3, a plurality of spiral grooves 4 (six grooves in the figure) opening at the tool tip and the outer periphery are formed on the outer periphery of the blade 3. An outer circumferential cutter 5 that draws a spiral around the tool axis O is formed at one end in the direction. The spiral groove 4 has a rake face 6 that extends from each peripheral cutter 5 toward the tool rotation direction (direction of arrow A in the figure), and a flank surface 7 that extends from the outer peripheral cutter 5 toward the opposite side of the tool rotation direction. As the rake face 6 goes from the outer peripheral cutter 5 toward the tool rotation center P0, the outer peripheral cutter 5 and the tool rotation center P0
0 and gradually protrudes toward the tool rotation direction side relative to the virtual center line L1 connecting the outer circumferential cutter 5 with a negative radial rake angle γ. This radial rake angle γ is -10°
A range of -19°30' is used. If the negative angle is smaller than -10°, the cutting edge strength of the peripheral blade 5 may be impaired.On the other hand, if the negative angle is set to be larger than -19°30', the sharpness of the peripheral blade 5 may deteriorate excessively. This is because it occurs.

The flank 7 of the helical groove 4 is formed by forming first and second flanks 8 and 9 in sequence from the peripheral cutter 5 toward the opposite side in the tool rotation direction. The first flank 8 is moved back toward the tool center at a constant slope as it moves away from the peripheral cutter 5, and the clearance angle α, that is, the inclination angle of the first flank 8 with respect to the tangent L2 of the peripheral cutter 5 is 1
It is set in the range of 5° to 23°. If it is less than 15 degrees, premature wear of the peripheral cutter 5 due to insufficient relief angle is unavoidable, while if it exceeds 23 degrees, the cutting edge angle of the peripheral cutter 5 is insufficient, making it easy to break or fall off. Note that reference numeral 10 in the figure is a groove bottom surface connecting the second flank surface 9 and the rake surface 5, and is formed in a curved shape that curves toward the center in the tool radial direction.

Further, the helical angle of the rake face 6 of the helical groove 4 with respect to the tool axis is equal between each helical groove 4 and constant from the tip to the rear end of the helical groove 4. The outer diameter of the blade portion 3 is also constant from the tip to the rear end,
As a result, the torsion angle φ of each peripheral cutter 5 with respect to the tool axis O
are also constant and equal from the tip to the back. Here, a range of 35° to 45° is preferably used as the twist angle φ. If the angle is less than 35°, each peripheral cutter 5
The cutting resistance of 4 is high and may cause chipping, etc.
This is because if the angle exceeds 5°, the contact length of the peripheral blade 5 with the work material increases excessively, the biting ability of the peripheral blade 5 to the work material deteriorates, and wear of the peripheral blade 5 is accelerated.

As shown in FIGS. 1, 2 and 4, the blade portion 3
A gash 11 is formed at the tip of the blade corresponding to the spiral groove 4, and a gash 11 is formed at the tip of the blade at a position facing the gash 11.
Two bottom blades 12 are formed. These bottom blades 12 are made to protrude toward the tip side in the tool axis direction as they go from the center of the tool toward the outer circumference. The outer peripheral side of the bottom cutter 12 is bent in the opposite direction to the tool rotation direction, so that the bottom cutter 12 has a two-step inclination angle κ with respect to the tool radial direction.
1, has κ2. Further, the bottom surface 11a of the gash 11 retreats toward the rear end of the tool as it goes toward the outer circumference of the tool,
Its receding angle θ is 15°.

[0013] However, in the end mill constructed as described above, the radial rake angle γ of the peripheral cutting edge 5 is set to a smaller negative angle than the conventional one, thereby improving its cutting quality, while the clearance angle α is It is set within a range that does not impair the strength of the cutting edge of the blade, and the helix angle φ is also set within a range that does not impair the sharpness of the peripheral edge 5, and furthermore, the tool material is a cemented carbide equivalent to JIS classification K class 03 to 05. This prevents the peripheral blade 5 from chipping or falling off, improves sharpness, and efficiently cuts high-hardness materials.

In order to clarify the effects of the present invention, cutting tests were conducted for a certain period of time under the same conditions using an end mill according to the present invention and a conventional end mill, and then the state of damage to the peripheral cutting edge was investigated. The results are shown in FIGS. 5 and 6. The difference between the end mill according to the present invention used here and the conventional end mill is that the end mill according to the present invention has a radial rake angle of -19° and a number of teeth of 8. In the end mill of Comparative Example, the only difference is that the radial rake angle of the peripheral cutter is -9° and the number of teeth is 6, and other dimensions are set to be the same. Moreover, the cutting conditions are the same. Note that the work material used had a hardness of HRC61.

As shown in FIG. 5, in the end mill according to the present invention, although there are some chips C attached to the peripheral blade 5, no chipping or falling off of the peripheral blade itself is found. On the other hand, as shown in FIG. 6, in the conventional end mill, a large amount of detachment occurred in the outer peripheral cutter 5 and a defective part 20 was formed, which clearly shows the superiority of the present invention.

[0016]

As explained above, the present invention provides an end mill in which the peripheral cutting edge is integrally molded, with the radial rake angle of the peripheral cutting edge being set in the range of -10° to -19° 30'.
The clearance angle is set in the range of 15° to 23°, the helix angle is set in the range of 35° to 45°, and the tool material is made of cemented carbide corresponding to JIS classification K class 03 to 05. Therefore, it has the excellent effect of preventing the peripheral blade from chipping or falling off without impairing the sharpness of the peripheral blade, and enabling efficient cutting of high-hardness materials.

[Brief explanation of drawings]

FIG. 1 is a side view of an end mill according to the present invention.

FIG. 2 is a view taken from the direction II in FIG. 1;

FIG. 3 is a sectional view taken along line III-III in FIG. 1;

FIG. 4 is an enlarged view of the bottom blade portion of FIG. 1;

FIG. 5 is an enlarged view showing the state of the outer peripheral edge when cutting a high-hardness material is continued for a certain period of time with the end mill according to the present invention.

FIG. 6 is an enlarged view showing the state of the outer peripheral edge when a conventional end mill continues cutting a high-hardness material for a certain period of time.

[Explanation of symbols]

1 Tool body 5 Peripheral blade γ Radial rake angle α Relief angle φ　Torsion angle O Tool axis

Claims (1)

[Claims] 1. An end mill in which a peripheral cutter that draws a spiral around the tool axis is integrally molded on the outer periphery of a tool body, wherein the radial rake angle of the outer peripheral cutter is -10° to -10°.
-19° 30', the relief angle is set in the range 15° to 23°, the helix angle is set in the range 35° to 45°, and the material of the tool body is JIS classification K class 0.
An end mill characterized in that a cemented carbide corresponding to No. 3 to No. 05 is used.