Method and automatic machine for machining a gear wheel

Patent metadata

Field	Value
Publication number	US-9427816-B2
Application number	US-201414276597-A
Country	US
Kind code	B2
Filing date	May 13, 2014
Priority date	May 14, 2013
Publication date	Aug 30, 2016
Grant date	Aug 30, 2016

Abstract

The axis of rotation of a gear wheel subjected to thermal treatment and comprising at least one intermediate crown wheel and a pair of lateral tubular hubs arranged on opposite sides of the crown wheel is restored automatically by coupling a first of the hubs to a head rotating about a fixed axis of own rotation axis, displacing the other hub in a direction transverse to the fixed axis until both of the hubs and the crown wheel are brought into positions substantially sharing the fixed axis and providing on each of the hubs a respective centring surface sharing the fixed axis without uncoupling the first hub from the rotating head and keeping the gear wheel in a vertical and angularly fixed position.

First claim

The invention claimed is:

1. A method for machining a gear wheel comprising at least one outer crown wheel, a first hub and a second hub opposed to each other and projecting in cantilever fashion from opposite axial sides of said crown wheel, the method comprising the steps of: coupling said first hub to a motor-driven rotating head having an own fixed vertical axis of rotation; displacing said second hub in a direction transverse to said fixed axis; bringing said hubs into a position substantially sharing said fixed axis; and machining the hubs, providing on each of said hubs a respective inner centring surface sharing said fixed axis; the steps of bringing said hubs into a position substantially sharing said fixed axis and of machining the hubs themselves to obtain said inner centring surfaces are obtained without uncoupling said first hub from said motor-driven rotating head.

2. A method according to claim 1 , characterized in that the steps of bringing said hubs into a position substantially sharing said fixed axis and of machining the hubs themselves to obtain said centring surface are performed, keeping said axis in a vertical position.

3. A method according to claim 1 , characterized in that said centring surfaces are provided, keeping said gear wheel in an angularly fixed position about said fixed axis.

4. A method according to claim 1 , characterized in that formation of said centring surfaces is obtained, constraining said first hub on said rotating head and the second hub on a further retention head distinct from said rotating head.

5. A method according to claim 1 , characterized in that said centring surfaces are obtained simultaneously.

6. A method according to claim 1 , characterized in that said first hub is coupled to said rotating head by inserting a configurable retention member within a grooved stretch of said first hub and modifying the constraint with said retention member by varying the configuration of said retention member during execution of said steps.

7. A method according to the claim 6 , characterized in that the constraint between said retention member and said first hub is modified by activating one or more retention devices co-operating with an internal groove of said first hub.

8. A method according to claim 1 , characterized in that the step of bringing said hubs into a position substantially sharing said fixed axis comprises the operations of: displacing at least one electrical sensor towards said gear wheel in a direction transverse to said fixed axis; bringing at least one feeler of said electrical sensor into contact with a lateral surface of said gear wheel; rotating the gear wheel about said fixed axis; detecting a plurality of electrical signals, which correspond to an instantaneous eccentricity of said surface with respect to the fixed axis and are proportional to the instantaneous displacement of said feeler in said direction; processing said signals via an electronic processing and control unit; and governing, via said electronic processing and control unit, at least one motor-driven actuator that acts on said gear wheel to vary the eccentricity of said second hub with respect to said fixed axis as a function of said processing of the electrical signals.

9. A method according to claim 8 , characterized in that the step of bringing said hubs into a position substantially sharing said fixed axis comprises the operations of: identifying a plurality of outer lateral surfaces of said gear wheel distributed along said fixed axis; using one said electrical sensor for each said lateral surface; processing, via said control unit, the electrical signals sent by said electrical sensors; and issuing a single control signal to said motor-driven actuator.

10. A method according to claim 9 , characterized in that said lateral surfaces are circumferential surfaces that delimit externally one said first hub, one said second hub, and said crown wheel.

11. A method according to claim 9 , characterized in that at least one of said lateral surfaces is an axial surface orthogonal to said fixed axis.

12. A method according to claim 1 , characterized in that said centring surfaces are obtained by rotating said gear wheel about said fixed axis.

13. An automatic machine for machining a gear wheel, comprising at least one outer crown wheel, a first hub, and a second hub opposed to each other and projecting in cantilever fashion from opposite axial sides of said crown wheel, the machine comprising a motor-driven rotating head having an own fixed vertical axis of rotation and comprising motor-driven retention means and controllable-retention means, the machine further comprising motor-driven movement means for displacing said second hub in a direction transverse to said fixed vertical axis to bring it into a position substantially sharing said fixed vertical axis, a first motor-driven tool head and a second motor-driven tool head that are mutually independent for obtaining on the first and on second hubs, respectively, a respective inner centring surface sharing said fixed vertical axis, a plurality of position sensors, which co-operate with respective surfaces of the gear wheel for detecting the deviation of the surfaces themselves from said fixed vertical axis and are designed to issue respective electrical position signals, and a control unit for processing the electrical signals issued by said position sensors and issuing signals for controlling said motor-driven heads, said sensors, and said motor-driven retention and movement means, as a function of the signals issued by said position sensors.

14. A machine according to claim 13 , characterized in that both of said tool heads extend coaxially with respect to said fixed vertical axis in positions set at axial distances apart.

15. A machine according to claim 13 , characterized in that said motor-driven retention means and controllable-retention means comprise an elongated retention member sharing said fixed axis and designed to be inserted within a grooved stretch of said first hub, a plurality of radial retention pins carried by said retention member, and further motor-driven actuation means for actuation of said pins, said means being controlled by said unit for displacing the pins radially between a retracted resting position and an extracted retention position in which the pins are forced within respective compartments of said grooved stretch.

16. A machine according to claim 15 , characterized in that said rotating head comprises two rings of said pins that may be actuated independently of one another.

Assignees

• Ge Avio Srl

Inventors

• Milletari Salvatore
• Siccardi Rinaldo

Classifications

• Y10T408/175

  to control relative positioning of Tool and work · CPC title

• B23B41/00

  Boring or drilling machines or devices specially adapted for particular work {(surgical drilling machines A61B17/16)}; Accessories specially adapted therefor · CPC title

• B23F17/006

  using different machines or machining operations · CPC title

• B23B31/025 Primary

  for gears · CPC title

• B23F23/1218 Primary

  Checking devices for controlling workpieces in machines for manufacturing gear teeth · CPC title