JPS6179519A - Face milling cutter - Google Patents

Abstract

PURPOSE:To enable a desired tooth profile to be designed, by decreasing a stress concentration coefficient by an increase by an edge point radius in a dedendum cutting edge and increasing bending strength. CONSTITUTION:An edge point radius Rk1 in a dedendum cutting edge 11b, 12b is increased in no relation to the conventional standard. In this way, a cutter, increasing also a dedendum radius, decreases a stress concentration coefficient. The cutting edge 11b, 12b lowers exceeding a tooth bottom line in accordance with an increase of the radius Rk1, but a curved tooth bottom cutting edge 11c, 12c rises up successively to the tooth bottom line, forming a new tooth bottom line. A position of the new tooth bottom line in a range on calculation is set by adjusting a mutual relation between the edge point radius Rk1 of the dedendum cutting edge 11b, 12b, radius of curvature Rb of the tooth bottom cutting edge 11c, 12c, and the position of a flank 11d, 12d.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a face mill cutter for cutting gears such as bevel gears and hypoid gears.

(Prior art) The above face mill cutter has an outer blade and an inner blade that cut one side surface and the tooth bottom on the outer periphery of a disk-shaped body, respectively, and have a central bore for attachment to the main shaft of a gear cutting machine. Known are double-edged cutters for forming or shaping that have 11 girder blades alternately planted, and triplex cutters for forming that have a center blade that cuts only the bottom of the tooth in addition to the above-mentioned blades.

FIG. 5 shows the relative arrangement of the outer blade and inner blade in the conventional double-edged cutter, and FIG. 6 shows the cutting l+! d shows the shape of the NFC fungal groove.

In Fig. 5, 2 is shown, 1 is an externally toothed blade, and 2 is an internally toothed blade. In the external blade 1, 1a is a tooth surface cutting blade that cuts one side surface, 1b is a tooth root cutting blade that cuts the 7th round part of the tooth root, 1c is a seedbed cutting blade that cuts the tooth bottom, and 1d is a tooth surface cutting blade. The inner blade 2 also has a flank cutting edge 2a and a root cutting edge 2b, which are flanks formed on the opposite side of the cutting edge 1a.

A tooth bottom cutting edge 2c and a flank 2d are formed. Maf
cB-B is the tooth root line, X-X is the root center line, W is the point mark, Rk is the moonlight radius attached to the eye cutting blades 1b and 2b, C
In FIG. 6, k is the top clearance, Rz is the root radius, F is the flat surface formed on the bottom of the tooth, and Hlk is the effective tooth thickness.

The dimensions of the cutting edge radius Rk are roughly standardized due to the need to form the above-mentioned flat part F and the strength and wear resistance of the root cutting edge.According to Gleason's cutter table and other standards, this Rk is the point width W. C) Less than 172 to approximately 1/4 (defined between 0.

(Problem) By the way, when gears are cut using such standards, there is a problem in that modifications to be made to the gear, such as reduction in tooth thickness, are restricted, and as a result, a desired tooth profile cannot be designed. The reason is as follows.

In other words, factors such as contact ratio, pressure angle, tooth thickness, and tooth thickness are involved in the bending strength of the teeth, but when attempting to make modifications that reduce the bending strength, such as reducing the tooth thickness, It is extremely effective to compensate for this decrease in bending strength by dispersing the stress generated at the root of the tooth, specifically by increasing the root radius Rz and reducing the stress concentration factor. However, the tooth base radius is determined as a function of the cutting edge radius Rk, and this cutting edge radius is subject to the above-mentioned restrictions, so there is a limit to strength compensation.

Therefore, an object of the present invention is to make it possible to set the cutting edge radius to a large value without following the conventional standard.

(Means of the Invention) The means of the present invention that solves the above problems is to set the cutting edge radius of the root cutting edge following the tooth flank cutting edge to 1/2 or more of the point width, and to It has a curved tooth bottom cutting edge that is connected to the surface.

(Function) The above means increases the cutting edge radius of the dedendum cutting edge regardless of the conventional standard, so the dedendum radius also increases, thereby reducing the stress concentration factor.

However, as the cutting edge radius increases, the root cutting edge falls beyond the conventional tooth root line, but since the curved tooth root cutting edge continues to rise, a new tooth root line is created at an appropriate location. can be formed.

Therefore, by adjusting the mutual relationship between the cutting edge radius of the root cutting edge, the radius of curvature of the root cutting edge, and the flank position, a new root line position can be established within the calculated range, and therefore the apex [! l
& can be set.

(Example) FIG. 1 shows an example of a double-sided cutter according to the invention, 11 is an outer blade, and 12 is an inner blade. The outer blade 11 and the inner blade 12 have the same tooth surface cutting edges 1ia and 12a1 as the conventional ones, root cutting edges 11b and 12b of the cutting edge radius Rkl, respectively, and a radius of curvature R.
A curved tooth bottom cutting edge 11d and 12d are formed in series. FIG. 2 shows an example of a triplex canter according to the present invention, in which the aforementioned central blade 13 is disposed between the outer blade 11 and the inner blade 12. Rr is the radius of curvature of the cutting edge 13a of this central blade.

The solid line in Fig. 3 shows the shape of the tooth groove cut with the double-sided force cap in Fig. 1, and 11a' and 12a' are the tooth surface cutting edge 1.
Tooth flanks cut with 1a and 12a, 11b! and 1
2b' is the tooth root cut by the root cutting edges 11b and 12b, Rzl is the tooth root radius, 11c' and 12c' are the tooth bottoms cut by the tooth root cutting edges 11c and 12c, and the root has a curvature. It protrudes with a radius Rb'.

The two-dot chain line 13' shows the cutting line when the central blade 13 of the triplex cutter shown in FIG.

FIG. 4 shows an enlarged view of the cutting edge shape of the outer cutter blade 11 as an example, and shows the outer cutter blade 1 as an example.
The cutting edge shape is a two-point chain i! j! It is also written with .

In this conventional type, T is the contact point between the root cutting edge 1b and the tooth flank cutting edge 1a, O' is the center point of the cutting edge radius Rk, and R
k-w/2, where B-B and Ck are divided by the root line and the top line of this combination.

In the actual legend, the cutting edge radius Rkl is set to be 1/2 or more of the above point width W, as mentioned above, and the experimentally optimum value is 0.7 to 0.9)W'''c.O is the line molecule O The center point of the root cutting edge 11b set on the extension of ' (TO=Rk
l), BJ-Bl is the root line, Ckl is the top gap, ΔCkI
U The increment relative to the conventional top gap Ck, Ckz is the calculated top gap, and ΔCkz is the increment.

The top gap Ckz is calculated by the usual method as follows.

Taking a large gear bevel wheel as an example, the number of teeth of the large gear is N.
1 If the pitch circle diameter is Dl and the torsion angle is W, then the normal module stop at the average cone distance is given by Mn = D Cog W/N, and the effective tooth thickness at this time is Hk = K
-Mn (!”l) K is a tooth bamboo coefficient and generally takes a value of 3.5 to 4.

The top Ckz is Ckz = 0.15 Hk +0.05 = 0.15
K-M n + 0.05= (0,525-0,6
) Mn + 0.05 (-) and △Ckz = (0, +5 ~ 0.25) W (
However, the conventional top clearance Ck is calculated to be small υ due to the above-mentioned restriction on the cutting edge radius Rk.

Bz - B2 to J: 5.Meet at the calculated tooth bottom line, ΔC
1 of kz 'lΔCkx. In the VJ section, the tooth bottom-like B
Set the site of t-Bl. (In the example, ΔCkz
>Test kl) Next, this usual tooth bottom cutting blade 11cμ has an arc shape with the ail rate radius Rh as its radius, and the Yamamoto cutting blade 11 continues to follow the tooth bottom line Bl-Bl, and then it is placed in the seedbed. center line
-X', the oil leak 1id is connected to this n. It is appropriate to set the value of the radius Rb to 1g and (0.25 to 0.35) W considering the Nit abrasion resistance and breakage resistance of the blade portion.

The root cutting edge i2b of the inner blade 12 and the bottom cutting edge 12
c is also formed in the shape of M. In this case, it is common practice to match the tooth bottom & it with the tooth bottom line Bl-B1 of the outer blade.

In addition, in the tribulenx cutter shown in Figure 2, the center blade 1
3, the cutting edge 13at can be lowered until it touches the root line Bz -B2 on it, and the radius of curvature Rrl of the cutting edge 13a
! The tooth bottom cutting edge 11 is designed in consideration of the wear resistance and breakage resistance of the cutting edge.
It is determined to be approximately equal to the radius of curvature Rb of c.

(Effects) As explained above, the present invention reduces the stress concentration coefficient at the root of the tooth and increases the bending strength. It's about raising the third degree.

[Brief explanation of drawings]

Figures 1 and 2 are explanatory views of the main parts of the face and mill cutter showing an embodiment of the invention, respectively, and Figure 3 is an explanatory view showing the shape of the tooth groove cut by the canters of Figures 1 and 2. , Fig. 4 is an explanatory diagram that further enlarges the main parts of Figs. : Tsute cutting zone nf
c is an explanatory diagram showing the tooth groove shape. 1.11...Outer blade 2.12...-Inner blade blade 13...-Central blade 1a, 11a, 2a, 12a...Tooth surface cutting edge Ib
, llb, 2b, 12b -- root cutting edge 1c,
Ilc, 2c, 12c... tooth bottom cutting edge 1 d, li
d, 2d, 12d... Oil escape Rk, Rkl... Cutting edge radius Rb of the tooth root cutting edge -- Curvature radius W of the tooth bottom cutting edge... Point width

Claims (1)

[Claims] In a face mill cutter for gear cutting equipped with an outer blade and an inner blade, the cutting edge radius of the root cutting edge following the tooth surface cutting edge of these blades is set to 1/2 or more of the point width, and the tooth A face mill cutter with a curved bottom cutting edge that continues from the original cutting edge to the flank of the blade.