US 4,649,671 AGranted

Method for the precision working of the flanks of gears with a gear-shaped tool coated with hard-material granules and a method for dressing such a tool

AssigneeCarl Hurth Maschinen- und Zahnradfabrik GmbH & Co.

InventorsManfred Erhardt, Herbert Loos, Gerhard Reichert

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Abstract

A method for the manufacture or machining of the tooth system of straight or helically toothed, externally or internally toothed, nonhardened or hardened workpiece with a toothed tool, the tooth flanks of which are coated with a cubic boron nitride (CBN). The workpiece and the tool roll along with a single-flank contact and are supported by a guide-gear pair which also roll along with a single-flank contact. The contacting flanks of the workpiece-tool pair are the mating flanks for the contacting flanks of the guide-gear pair. To protect the CNB-coating, the tool is already driven at a speed which is necessary for an optimum chip removal before the tool tooth flanks start to work on the workpiece tooth flanks.

Claims3

Dependent claims

A method for the precision working of straight or helically toothed, externally or internally toothed, nonhardened or hardened workpieces with a gear-shaped tool, the tooth flanks of which are provided with a coating of cubic boron nitride (CBN) granules on an apparatus wherein the tool and the workpiece are each connected to a pair of mating guide-gears having the same speed ratio as the tool-workpiece pair, and in which the tool with the workpiece roll along on another in such a manner that during a machining operation in each case only the right or the left flank of the tool teeth engage the workpiece teeth and a means is provided for setting or adjusting the reciprocal angular position of the guide-gear and the tool for the purpose of effecting a change of the flank contact, comprising the following method steps:

(a) moving the tool into the tooth system of the workpiece or vice versa up and until a center 20 distance corresponding with the start of the machining operation is attained;
(b) rotating the tooth system of one of the two parts of the workpiece-tool pair relative to the tooth system of the guide-gear pair until the machining tool flank engage the workpiece flank which is to be machined and the corresponding mating counter-flanks of the guide-gear pair engage;
(c) moving the tool with its guide-gear and the workpiece with its guide-gear away from one another while maintaining the counter-flank contact in the guide-gear pair up and until a condition whereat backlash exists on both sides of the tool tooth;
(d) activating the rotary movement and accelerating to the working speed;
(e) vertically feeding the tool relative to the workpiece (reducing the center distance) with a simultaneous chip removal, whereby the tool is guided by the guide-gear pair so that only one flank of the tool teeth engages the workpiece teeth;
(f) moving the tool and the workpiece apart, while the guiding is maintained by the guide-gear pair, and then deactivating the rotary movement;
(g) repeating the operation for the other tooth side of the workpiece and the tool.

4 more elements

A method for dressing of a straight or helically toothed, externally or internally toothed tool, which is used for the precision working of toothed workpieces and the tooth flanks of which are provided with a coating of cubic boron nitride (CBN) granules, with a gear-shaped dressing wheel, the tooth flanks of which are provided with a coating a hard-material granules of a greater hardness than those of the tool on an apparatus wherein the tool and the dressing wheel are each connected to a pair of mating guide-gears having the same speed ratio as the tool dressing-wheel pair, and in which the tool with the dressing wheel roll along on one another so that during a dressing operation in each case only the right or the left flank of the tool teeth engages the dressing-wheel teeth and a means is provided for setting or adjusting the reciprocal angular position of the guide-gear and the tool for the purpose of changing the flank contact, comprising the following method steps:

(a) moving the tool which is to be dressed into the tooth system of the dressing wheel or vice versa;
(b) reducing the center distance to the smallest center distance of the tool and dressing wheel;
(c) rotating the tooth system of one of the two parts of the tool-dressing-wheel pair relative to the tooth system of the guide-gear pair until the machining dressing-wheel flanks engage the tool flank to be dressed and the corresponding mating counter flank of the guide-gear pair engage and backlash exists on the respective other flanks of the guide-gear pair and the tool-dressing wheel pair;
(d) moving the tool with its guide-gear and the dressing wheel with its guide-gear apart while maintaining counter-flank contact in the guide-gear pair up and until a condition whereat backlash exists on both sides of the tool tooth;
(e) activating the rotary movement and accelerating to the working speed;
(f) vertically feeding the tool relative to the dressing wheel (reducing the center distance) with a simultaneous dressing of the tool flanks whereby the tool is guided by the guide-gear pair in such a manner that only one flank of each tool tooth engages the dressing-wheel teeth;
(g) moving the tool and the dressing wheel apart while guiding is maintained by the guide-gear pair, and then deactivating the rotary movement;
(h) repeating the operation for the counter-flanks of the tool and the dressing wheel.

5 more elements

Dependencies are inferred from the claim text.