Turning – Process of turning
Patent
1997-10-27
1998-12-01
Pitts, Andrea L.
Turning
Process of turning
82120, 82121, 408 35, B23B 900, B23B 3920
Patent
active
058423923
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an indexing device which is structured such that a rotary table is indexed while rotated about a given rotary center relative to a base table, and to a method of driving the same, such as for example, an indexing device adapted for a turret device used by a lathe, and a method of driving the same.
BACKGROUND TECHNOLOGY
There has been recently an increasing demand for an NC lathe provided with a turret device since a machining apparatus, particularly, a lathe is able to realize automatic machining operations at high speed and can cope with a computer-integrated flexible manufacturing system.
The turret device is structured such that a rotary table called a turret which is provided on a tab base table (tool slide), and has normally 5 to 12 indexing positions, is indexed while rotated (hereinafter referred to as simply indexed). Tool mounting portions are formed on an outer periphery or end surface of the turret, and various tools such as turning tools and drills are mounted on these tool mounting portions wherein an appropriate tool is selected from the various tools depending on the type of machining process desired so as to index the selected tools in machining positions.
In indexing devices such as the turret, a pair of positioning engaging members which are engageable with and disengageable from each other are provided so that the selected tool is indexing in a given indexing position, and the tool which was arranged in the indexing position is positioned and fixed to the indexing position.
This pair of positioning engaging members is provided between the base table and a turret, wherein the turret may be freely indexing or may be positioned and fixed to a given indexing position when the positioning engaging members engage with or disengage from each other.
In the turret device of the NC lathe, crown gears such as curvic couplings which mesh with each other are generally employed as the positioning engaging members. In the positioning engaging member of this type, when a turret side coupling is moved in the axial direction relative to a base table side coupling, the engagement and disengagement between these couplings is performed.
The engaging and disengaging operations of the positioning engaging members, namely the driving of the turret side coupling in the axial direction, has been carried out by a hydraulic or pneumatic actuator.
However, the hydraulic or pneumatic actuator requires oil under high pressure or compressed air as an operating medium, and hence it requires a power unit including an accumulator, a pump and a tank. Meanwhile, a servomotor capable of controlling with high accuracy and fast response has been frequently used as a driving source for driving each component of a recent machining apparatus such as an NC lathe, and hence the holding and releasing of a workpiece by a chuck and the indexing of the turret, which have been carried out by a hydraulic system, are now frequently carried out by the servomotor.
Accordingly, the conventional indexing device provided with a hydraulic or pneumatic actuator for carrying out only the engagement and disengagement between the positioning engaging members such as curvic couplings incurs high costs in terms of facilities therefor, such as power units and piping, etc., which causes a problem that the apparatus is uneconomical and becomes large-sized because of the provision of the power unit, and it also becomes a source of noise.
Further, when the positioning engaging members engage with each other using a hydraulic or pneumatic actuator, there are drawbacks in that they are cracked or chipped by the shock which is generated when a pair of positioning engaging members strike against each other, and the accuracy thereof is deteriorated owing to the friction therebetween.
Still further, when the hydraulic or pneumatic actuator is used for engagement and disengagement between the positioning engaging members, a sensor for confirming the completion of the operation of the actuator is required. Acco
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Pfeifer Wolfgang
Shinohara Hiroshi
Sugimoto Kenji
Citizen Watch Co. Ltd.
Pitts Andrea L.
Tsai Henry W. H.
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