Multiple-spindle automatic lathe

Details Multiple-spindle automatic lathe Multiple-spindle automatic lathe

1985-04-03

1987-02-03

Larson, Lowell A.

Turning

Process of turning

82 2B, 82 28R, B23B 900

Patent

active

046401580

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a multiple-spindle automatic lathe with a spindle drum indexable by a spindle drum drive relative to a stationary machine frame step-wise into a number of indexing positions corresponding to the number of work spindles, in which spindle drum the work spindles are rotatably mounted, with one individually controllable electric motor per work spindle, with supply devices for the electric motors and with control devices to control the speed of the electric motors.
Such a multiple-spindle automatic lathe is described in German Pat. No. 1 265 539. In the known automatic lathe, each of the electric motors associated with one work spindle or workpiece spindle, respectively, is attached to the inside of an attachment drum which is a component of the spindle drum. The spindles and the motor shafts are, furthermore, each provided with V-belt pulleys over which a V-belt connecting the motor to the associated spindle runs.
A disadvantage of the known multiple-spindle automatic lathe is the large space requirement for the attachment drum and the electric motors which are arranged radially outside of the work spindle relative to the axis of rotation of the spindle drum. The drive via driving belts is also relatively loud and involves high maintenance and repair expenditure in view of the fact that driving belts are distinctively subject to wear and tear.
Also known from the German publication ZwF 76 (1981) 1 pages 24 to 27 is a multiple-spindle automatic lathe of the generic kind mentioned at the outset, wherein the individual work spindles each include an angle with the axis of rotation of a spindle drum of spindle-nose-type configuration, wherein there may be associated with each work spindle an individually controllable electric motor which is attached to the machine frame and, as described in detail in German laid open patent application No. 2 338 207, may be coupled via an axially displaceable coupling with the pertinent work spindle and released therefrom.
A disadvantage of this solution is that during the indexing of the spindle nose or the drum, the speed of the spindles cannot be controlled, and substantial frictional heat losses occur in the couplings, resulting in the automatic lathe being unnecessarily heated up, as is also the case in multiple-spindle automatic lathes having for all of the work spindles one common drive serving to drive the spindles via couplings associated individually with the spindles (see German laid open patent application No. 2 443 087).
Unfavorable acceleration moments which shorten the service life of the machine and, in the end, limit the operating speed of the automatic lathe also occur in the known multiple-spindle automatic lathes comprising coupling devices between the work spindles and the drive means during the indexing of the spindle drum on account of the changes in speed of the work spindle involved therein.
Departing from the state of the art, the object underlying the invention is to improve a multiple-spindle automatic lathe of the kind mentioned at the outset so as to obtain high service life with high operating efficiency and high precision during trouble-free operation.
This object is attained in the multiple-spindle automatic lathe of the kind mentioned at the outset, in accordance with the invention, in that each of the work spindles directly comprises the shaft of the associated electric motor, in that all of the electric motors are fed via slip ring means on a portion of the shaft of the spindle drum and via brush means which are attached to the machine frame adjacent to the slip ring means, and in that the control devices constitute part of speed and position control devices comprising per work spindle one rotary angular position detector means each for absolute value angle coding, which includes a detector rotating synchronously with the associated work spindle and a sensor means arranged stationarily relative thereto.
An important advantage of the automatic lathe according to the invention is that due to the work spindles directly compr

REFERENCES:
patent: 3792633 (1974-02-01), Filipieu et al.
patent: 3946298 (1976-03-01), van de Loo
patent: 4133230 (1979-01-01), Inaba et al.
patent: 4158319 (1979-06-01), Blockley et al.
patent: 4185366 (1980-01-01), Gilbert
patent: 4250775 (1981-02-01), Jerue et al.
CNC--Steuerung, fur ein mehrspindliges Drehbearbeitungszentrum Von Prol. Dr. Ing. G. Spur und Dr.-Ing. H. Mathes, Berlin ZwF76 (1981), pp. 24-27.

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