RU2392096C2 - Method for treatment of cogs in helical cylindrical geared wheels and device for its realisation - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: method is realised in process of continuous rotation of stock, even reciprocal motion of tool in direction parallel to axis of stock and its withdrawal during reverse motion. In order to increase accuracy in treatment of gear rims of smaller diametre, speed of tool motion and speed of stock rotation are selected by given equations depending on angle of processed wheel cog inclination on dividing cylinder. Device is installed on vertical hobbing machine and comprises body, rack gear and tool with the possibility of reciprocal motion, frame installed on support with vertical guides, there is a hole arranged in frame, in which gear is installed with the possibility of rotation, some cogs in which are cut to diametre of indents, engaged with gear rack fixed on slider installed in frame guides and equipped with cutter holder with cutter and counterweight.

EFFECT: increased accuracy in treatment of gear rims of smaller diametre.

4 cl, 1 dwg

Description

The invention relates to the field of metal cutting, in particular to a technology for cutting teeth of helical gears, including gears with internal teeth.

Known methods of processing such gears by milling with disk or finger milling cutters on gear hobbing machines by the unit pressure method. However, such methods do not provide the necessary accuracy of the toothwork and, in addition, are possible only when machining gear rims with internal teeth of a relatively large diameter of the pitch circle.

There is also a known method of manufacturing helical gears by gear grinding, which requires the use of machines with helical guides and helical cutters, which significantly limits the choice of the angle of inclination of the teeth to a certain value.

The closest adopted for the prototype is the method of continuous gearing during the reciprocating movement of the tool in the form of a cutter in the direction parallel to the axis of rotation of the workpiece, and when the tool moves backward, it moves away from the product, and the workpiece rotates continuously, consistent with the movement of the tool (see USSR author's certificate No. 21204335 of January 18, 1982).

A method for machining helical cylindrical wheels with a tool with continuous rotation of the workpiece, uniform reciprocating motion of the tool in a direction parallel to the axis of the workpiece, and its removal in the reverse stroke, in which the movement of the tool with speed V _p during the stroke is kinematically connected with the peripheral speed V _{h of the} machined wheel on the dividing cylinder by the dependence:

where β is the angle of inclination of the tooth line on the surface of the dividing cylinder of the machined wheel.

The magnitude of the speed V _s is determined by the dependence:

where m is the module, mm;

k is the number of teeth of the machined wheel between successive tool strokes.

Substituting the values of V _s in the formula (1), we obtain:

or

In the case of using a rack and pinion mechanism with a gear pitch diameter d _M for communicating a rectilinear uniform movement of the tool, the speed V _p in the formula (4) will receive:

where d _M is the pitch diameter of the rack gear, mm.

n is the frequency of rotation of the rack gear, rpm;

The tooth planing process in comparison with milling has the advantage that under the same processing conditions (processed material, module, cutting speed and cut sections), the cutting path and the number of loading cycles of the cutting edge are 2-4 times less. The profile of the tool corresponds to the profile of the cavity of the tooth being machined in a normal section.

A device for gearing on a vertical hobbing machine is known, adopted for the prototype, comprising a housing, a rack and pinion gear and a tool having a reciprocating movement (see USSR author's certificate No. 1373500 of 01/05/1984). This device does not allow to process helical crowns of small diameter with an internal tooth.

A device for processing helical gears on a vertical gear milling machine is proposed, including a housing, a rack and pinion gear and a tool with the possibility of its reciprocating movement, which is equipped with a frame with vertical guides mounted on a support, a hole is made in the frame in which the gear is rotatably located , part of the teeth of which is cut to the diameter of the depressions, which engages with a gear rack mounted on a slider installed in the frame guides, nnom toolholder with the cutting tool and the counterweight.

To implement the proposed processing method, the inventive device developed allows to process gear helical gears with an internal tooth in a wide range of tilt angles of teeth with a small diameter.

As can be seen from the drawing, the device is mounted on the housing 1 of the caliper of a vertical hobbing machine and connected to its spindle 2.

The device consists of a frame 3 with vertical guides parallel to the axis of rotation of the machine table. A hole is made in the frame, in which the gear 4 is horizontally mounted for rotation, part of the teeth of which is cut to the diameter of the depressions. The remaining teeth form a sector that engages with a gear rack 5 mounted on a slider 6 mounted in the guides of the frame 3. The slider is equipped with a swinging tool holder 7 with a cutter 8 and a counterweight 9 connected to the slider by a flexible link 10.

The slider is equipped with a spring 11 and a spring-loaded latch 12, interacting with the tool holder 7. On the frame 3 is rigidly fixed pusher 13, interacting with the tool holder.

The device operates as follows. At the beginning of the working stroke of the tool, the slider with the rail are in the upper position, the protrusion of the tool holder rests on the pusher 13, and the latch 12 holds the tool holder 7 in the working position. When the gear 4 is rotated, the first sector tooth in the direction engages with the lower tooth of the rack and begins to move the slider down. The cutter, mounted in the tool holder, cuts a depression on the surface of the workpiece, the inclination angle of which is determined by the ratio of speeds according to the formula (1).

The device is configured so that when the cutter leaves the cutting zone, the latch releases the tool holder, and the last tooth of the sector disengages from the upper tooth of the rail, and the spring 11 moves the cutter away from the workpiece. Since at that time the part of the gear 4, on which the teeth are cut, faces the rack, the counterweight 9 raises the slider to the upper position. With the emphasis of the pusher 13 in the protrusion of the tool holder, the latter rotates to the working position, and the latch under the action of the spring lowers and fixes the tool holder.

With further rotation of the gear 4, this cycle repeats.

The inventive combined technical solution allows to process gear helical gears with an internal tooth in a wide range of tilt angles of teeth with a small diameter.

Claims (4)

1. The method of processing helical cylindrical wheels with a tool with continuous rotation of the workpiece, uniform reciprocating movement of the tool in a direction parallel to the axis of the workpiece, and its removal during the reverse stroke, characterized in that the tool is moved using a rack and pinion gear with speed
V _p = π · d _Mn , mm / min,
where V _p is the velocity of the tool;
d _M is the pitch diameter of the rack gear, mm;
n is the frequency of rotation of the rack gear, rpm
and the peripheral speed of the workpiece is determined by the dependence:

mm / min
where V _s - peripheral speed of the workpiece;
m is the module of the gear being machined, mm;
k is the number of teeth of the machined wheel between successive tool strokes;
β is the angle of inclination of the tooth of the machined wheel on the pitch cylinder,
the angle β is determined in accordance with the dependence:

. 2. A device for processing helical gears on a vertical gear milling machine, comprising a housing, a rack and pinion gear and a reciprocating tool mounted on a support frame with vertical guides, a hole is made in the frame in which the gear is rotatably located, part the teeth of which is cut to the diameter of the depressions, which engages with a gear rack mounted on a slide installed in the guide rails, equipped with a tool holder with a cutter and counterweight. 3. The device according to claim 2, characterized in that it is equipped with a spring and a latch that interact with the tool holder. 4. The device according to claim 2 or 3, characterized in that the pusher is mounted on the frame, interacting with the tool holder.

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