RU2082568C1 - Method of worm wheel cutting - Google Patents

Abstract

FIELD: mechanical engineering; manufacture and repair of single and multiple start worm gearings and reduction gears. SUBSTANCE: cutting of worm wheels is carried out by small diameter worm milling cutter providing simultaneous rotating of milling cutter around its axis, circular feeding around axis coinciding with axis of working worm and radial feeding in direction of worm wheel rotation axis at alignment of axial plane of worm milling cutter with middle plane of worm wheel. Parameters of worm milling cutter and working worm are similar and axis-to-axis distances of working and machine tool engagements at moment of finishing of tooth cutting are the same. Angular velocities of worm milling cutter are in ratio equal to ratio of number of wheel teeth to number of starts of worm milling cutter. Number of starts of worm milling cutter is equal to number of starts of working worm. Depth-of-cut of worm milling cutter is set equal to tooth depth. EFFECT: enlarged operating capabilities. 2 cl, 2 dwg

Description

 The invention relates to mechanical engineering and can be used in machine repair.

A known method of manufacturing worm wheels, including processing the workpiece of the worm wheel by means of a worm cutter copies of the working worm [1]
The disadvantage of this method is that each transmission size requires the use of its copy cutter, which complicates the manufacturing process and leads to its increased material consumption.

 There is also known a method of cutting worm wheels of multi-way worm gears on a hobbing machine with a low-speed worm mill, the diameter of which is smaller than the diameter of the working worm (small diameter mill) [2] In addition to the rotation of the worm wheel and the worm mill when cutting the wheel, the worm mill is called planetary motion circular feed. In this case, the initial contour and the module of the teeth of the worm and the worm cutter of small diameter should be the same.

 This method, as the closest to the proposed technical essence, is selected as a prototype.

 The disadvantage of this method is the limitation with respect to the gearing of the worm gear. It cannot be used when milling the teeth of a worm wheel for a single start worm gear. In addition, to implement this method, additional studies are needed to identify the parameters, namely, the kinematics of machine engagement and two-parameter envelope during gear milling. It should also be noted that the term “inadequate” worm mill used in the source needs to be clarified; it creates uncertainty. In technology, by approach is the number of visits of the working worm. If the number of entries is equal to one, then the worm gear is called single-entry, but not low-entry. If the number of visits is greater than one, the worm gear is multi-start. The term "slow-moving" is undefined.

 The task to which the proposed solution is directed is to remove restrictions on the gearing of the worm gear in the method of cutting worm wheels, namely, the possibility of using when cutting worm wheels for both multi-start and single-start gears, i.e. expanding the scope of the method.

 The technical result that is achieved when solving the problem is expressed in the fact that the kinematics of the machine gear during gear hobbing strictly corresponds to the kinematics of the working gear.

 The problem is solved in that the method of cutting worm wheels on gear hobbing equipment by bending around a small diameter worm cutter, including the rotational movement of the worm cutter around its axis and at the same time its circular feed around an axis coinciding with the axis of the working worm, as well as radial feed in the direction of the rotation axis the worm wheel when combining the axial plane of the worm cutter with the middle plane of the worm wheel differs in that the worm cutter has the parameters of the working worm, the center shaft The working and machine engagement distances are the same at the moment of cutting the teeth, the angular speeds of the worm cutter and the worm wheel being cut are connected by a gear ratio equal to the ratio of the number of gear teeth to the number of visits of the worm cutter, and the number of visits of the worm cutter is equal to the number of visits of the working worm.

 The problem is also solved by the fact that the depth of penetration of the worm cutter into the workpiece of the worm wheel is set equal to the height of the tooth of the wheel.

 In FIG. 1 is a diagram of gear hobbing of a worm wheel with a small diameter mill; figure 2 diagram of the installation of the cutters of small diameter when gear hobbing the worm wheel.

 In FIG. Figures 1 and 2 show the producing surface 1, which is identical to the working worm of the worm gear, the cut worm wheel 2, the worm cutter 3 of small diameter, the eccentric mandrel 4 for installing the worm cutter 3, the supporting center 5, the trace 6 of the middle plane of the worm wheel 2.

In figures 1 and 2, the following notation is also introduced:
O _f axis of rotation of the worm cutter;
О _I axis of rotation of the producing surface I (working worm);
ω _{f the} angular velocity of the worm cutter 3;
ω _{1 the} angular velocity of the producing surface 1;
ω _{2 the} angular speed of the worm wheel 2 in the machine engagement (when cutting teeth);
R _{1 is the} estimated radius of the producing surface 1;
R _{f the} estimated radius of the worm cutter;
e eccentricity of the mandrel 4 for installing the worm cutter 3.

 The hobbing process is as follows.

где Z₁ и Z₂ соответственно число заходов рабочего червяка и число зубьев нарезаемого колеса.The workpiece 2 is installed on the table of the hobbing machine. The eccentrically made mandrel 4 is installed in the spindle unit of the machine. On the mandrel 4 install a worm mill 3 of small diameter on a movable landing. The free end of the mandrel 4 is supported by the center 5 (figure 2). The kinematics of the machine is adjusted according to the parameters of the working mesh, i.e. according to the parameters of the worm gear. Milling cutter 3 is informed simultaneously of rotation about its own axis O _f from a separate drive (movement of the envelope of cutting) and rotation together with axis O _f about axis O _{1 of} producing surface 1. With this rotation, the cutting edges of milling cutter 3 reproduce the desired producing surface 1. The rotation speed of the worm milling cutter 3 around the axis of rotation O ₁ set equal to the angular velocity of the producing surface I ω _f = ω ₁ (figure 1). Simultaneously with the rotation of the milling cutter 3, the radial feed in the direction of the axis of O ₂ rotation of the worm wheel 2 (workpiece) is reported, combining the axial plane of the worm cutter 3 with the middle plane 6 of the worm wheel 2 (Fig. 1). The depth of cut of the worm cutter 3 into the workpiece of the worm wheel 2 is set equal to the height of the tooth of the wheel 2. Moreover, the circular feed of the cutter 3 and the rotation of the worm wheel 2 during gear hobbing are connected by a gear ratio

where Z ₁ and Z _2, respectively, the number of visits of the working worm and the number of teeth of the cut wheel.

When cutting a worm wheel with specified parameters, the following conditions must be met:
the equality of the main parameters of the worm cutter and the working worm, such as: tooth modulus diameter of the dividing design cylinder, the angle of inclination of the helix and the profile angle of the original contour;
the equality of the interaxal distances of the working (in gear) and machine (on the machine) gears at the end of the cutting of the teeth of the worm wheel;
the equality of the number of visits of the producing surface (worm cutter) and the working worm.

When cutting a worm wheel for a single-start worm gear, the worm cutter should have a number of entries Z _f Z ₁ 1, when cutting a worm wheel for a double-start worm gear Z _f Z ₁ 2, etc. Therefore, the worm gear set is determined by the worm gear set.

 Thus, the proposed method can be used when cutting worm wheels for both single and multi-start worm gears without restrictions on the gearing of the worm gear.

Literature
1. Chasovnikov L.D. Gearing gearing. M. Engineering, 1969, p. 338.

 2. Copyright certificate of the USSR N 134547, cl. B 23 F 5/20, 1960.

Claims (2)

 1. The method of cutting worm wheels on gear hobbing equipment by rounding a small diameter worm cutter, including the rotational movement of the worm cutter around its axis and at the same time its circular feed around an axis coinciding with the axis of the working worm, as well as the radial feed in the direction of the axis of rotation of the worm wheel when aligning the axial plane of the worm cutter with the middle plane of the worm wheel, characterized in that the worm cutter has the parameters of the working worm, the center distance of the working and machine of the gearing at the moment of cutting the teeth is the same, the angular speeds of the worm cutter and the cut worm wheel are connected by a gear ratio equal to the ratio of the number of teeth of the wheel to the number of visits of the worm cutter, and the number of visits of the worm cutter is equal to the number of visits of the working worm.  2. The method according to claim 1, characterized in that the depth of cut of the worm cutter into the worm wheel blank is set equal to the height of the tooth of the wheel.

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