JPS61168420A - Method for cutting and grinding large bevel gear of large module about mp18-mp120 on the basis of generating gear cutting method - Google Patents

Abstract

PURPOSE:To enable a gear to be high accurately finished and its machining time to be reduced so as to decrease the machining expense, by mounting a generating gear cutting head to a large hob gear cutting machine and cutting the large bevel gear by an equiheight tooth generating end mill on the basis of the principle of generating gear cutting. CONSTITUTION:An equiheight tooth generating end mill 1, advancing to cut one tooth surface generating line toward the circular core O on a cone distance while holding a distance between the circular core O and the center of the equiheight tooth generating end mill to hoc, cuts an oblique line part to be removed toward an arrow head K in the drawing. And the equiheight tooth generating end mill is prepared on the basis of an involute curve XYZ with Y being a generating point by a normal tooth profile. Here the original point Q of the generating end mill is a crossing point between a straight line QB, being parallel to a straight line OYA and holding a distance hoc from it, and a straight line passing through the circular core O and forming an angle delta with the straight line OYA. Next, the hoc is determined by obtaining a groove width chord size in a small end part, that is, chordal thickness of the bottom in a face width corresponding to the generating point Y to be calculated. While the end mill, when it is worn, resets an offset quantity to a dimension after it is decreased by subtracting a half of the decreased amount of a blade thickness from the hoc.

Description

[Detailed description of the invention] If we order a special machine for large bevel gears that can cut modules up to about 100 mm from Gleason, it will cost a total of 1 billion yen, and space will also need to be secured, so it can be used for other purposes. It cannot be diverted.

Without purchasing a special machine, a large bevel gear can be cut in one piece using a unique generating gear cutting method using a generating gear end mill based on the generating gear cutting principle by attaching a large hob gear cutter opening and a generating gear cutting head. By performing tooth surface line gear cutting, we can cut high-precision large bevel gears that could only be obtained with dedicated machines.
The teeth are ground and manufactured. In addition, when machining large bevel gears is not required, the generating gear cutting head can be removed and the machine can be used for cutting cylindrical gears, which is the original purpose of the machine.

Conventionally, the method of cutting an end mill core perpendicular to the pitch cone, which has been practiced all over the world, requires cutting the tooth surface to correct the tooth surface. Unable to solve the problem, the product was produced with insufficient results.

It is possible to resolve these unsatisfactory aspects, achieve high-precision finishing using a unique generating gear cutting method, and significantly shorten machining time (no unnecessary cutting or correction gear cutting is required). The cost required is also incomparably cheaper than that of a dedicated machine.

[Brief explanation of the drawing]

Figure 1 shows gear cutting (tooth grinding) of a large module and large bevel gear using a constant height tooth generating end mill. FIG. 2 is taken along arrow GG in FIG. Showing the single tooth surface generation line tooth cutting, continue cutting on the pitch circle angle of the cone distance toward the circle center O while keeping the distance between the circle center O and the center of the equal height tooth generation end mill at hoc. (1) in Fig. 2 is an end mill for generating equal height teeth, and in particular, the diameter in Fig. 2 indicates the generating diameter. The shaded area in the direction of arrow K is about to be deleted. Figure 3 (1) shows the tooth profile of the end mill with equal height teeth. Point Y indicates the point on the pitch angle of the large end of the bevel gear to be cut, and the tooth profile is manufactured at right angles to the tooth based on the involute curve XYZ, but it is manufactured based on Y, which is the creation point. Now, assuming that the normal chord tooth thickness on the small end side of the bevel gear to be cut is S2, the formula for calculating the offset amount hoc of the end mill with equal height teeth is hoc = 0.5 x S.
2×cos γ0-(dd-c)×tan γ0-k where γ0 Pitch circle angle dd Denden dam c Top clearance k Clearance coefficient (k≧2mm) Therefore, if the blade thickness at the creation point of the end mill with equal height teeth is tb, , the calculation method is tb=2×hoc. The tooth profile of the large module large bevel gear is determined as an equivalent spur gear, and the relationship between the center O of the equivalent spur gear and the intersection Q for manufacturing an end mill with equal height teeth is as follows: This is the point where a straight line that is parallel to the straight line OA that passes through the creation point Y and maintains an interval of hoc intersects with a straight line that passes through the center O and forms an angle γ with the straight line OA. The formula for determining the generated involute curve of a constant-height tooth generating end mill with point Q as the origin is a formula using an involute function, and has already been completed, but will be omitted here. The tooth profile of the large end of the bevel gear to be cut is used as a reference, but after the constant height tooth generating end mill wears out or the blade is resharpened, etc., the blade shape (=tooth profile) of the constant height tooth generating end mill After confirming, half of the decrease in blade thickness tb is hoc
, and reset the offset amount of the equal height tooth creation end mill to the reduced dimension. Figure 4 shows a large hob gear cutting machine with a generating gear cutting head attached, and the angle can be changed within a range of approximately 90° in order to correspond to the pitch circle swing angle of the large module large bevel gear. . FIG. 5 is the arrow view H-H in FIG. 4. The explanations of the symbols in Figures 4 and 5 are as follows: (1) End mill for contour tooth creation (2) Bearing box (3) that supports (1) Precision slide when setting (2) to offset amount hoc Adjustment screw (5) that can be finely adjusted when setting the guide (4) (2) to the offset amount hoc (1) Pulley for (1) and belt (6) (1)
flywheel (7) (1) motor (8) generating gear cutting head body frame (9) workpiece large module large bevel gear (10) large hob cutting machine table (11) large hob cutting machine body Slide stand (12) Large hob cutter main body head Movable column (13) (8) with a permanently fixed circular arc rack (
Rotate the pinion gears (15) (14) that mesh with (14) and (13) that work when converting the angle between (1) and (7) to which it is attached to an angle corresponding to the pitch rotation angle of 9). The biggest feature of the gear cutting head is that it has steel properties when cutting gears,
The generating point of the equal height tooth generating end mill required for generating gear cutting can be set to the straight line OA connecting the center O of the large module large bevel gear to be cut and the center of the large hob gear cutting machine body.

Claims (1)

[Claims] Equal height tooth generating end mill (pressure angle is by type, gear cutting and
Carbide and Borazon containing diamond powder are available (including formulas for manufacturing these), generating gear cutting heads to which these are attached, and methods for gear cutting and gear grinding using these. (Large straight bevel gear, large hypoid skew bevel gear, large spiral bevel gear)