Gear cutting – milling – or planing – Milling – With means to control temperature or lubricate
Patent
1995-10-03
1997-09-09
Howell, Daniel W.
Gear cutting, milling, or planing
Milling
With means to control temperature or lubricate
409136, 409231, 82142, 310 54, 310 58, 310 59, B23B 1900
Patent
active
056649169
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a motor spindle cooled by a coolant for a machine tool, in particular, for a single workpiece spindle of a lathe.
A so-called motor spindle is a combination of a work spindle, i.e., the shaft of a machine tool provided for holding a workpiece to be machined, with a drive motor comprising a stator and a rotor arranged coaxially with one another and with the axis of the work spindle, with the essentially annular stator surrounding the rotor which is similarly of essentially annular construction, and the rotor surrounding the work spindle, and the rotor being rotation-wise fixedly connected to the work spindle.
In machine tools such as lathes, it is extremely important to prevent heat generated by operation of the machine tool from bringing about temperature-related changes in the shape of machine components which impair the dimensional accuracy of workpieces machined on the machine tool. This problem arises particularly in connection with motor spindles in which a regulatable three-phase motor is directly integrated into a spindle housing in which the work spindle is mounted, as special attention must be paid there to removal of the dissipated heat from the motor, more particularly, not only because the motor is accommodated in the spindle housing, but, above all, also because the maximum motor power is often put to full use during operation of such motor spindles.
Various cooling systems for such motor spindles are, therefore, known from the prior art. Reference is made, only by way of example, to the solutions proposed in the following publications: German patent 3 844 337 and EP-0 415 138-A of INDEX-WERKE GmbH & Co. K G Hahn & Tessky, German patent 3 902 592, German patent 2 724 440 and EP-0 094 680-A.
All of these known constructions attempt to conduct as fully as possible the heat generated by the motor of a motor spindle away from the motor spindle with the aid of a flowing coolant, in particular, air. However, they have not proven fully satisfactory. In the applicant's experience, this is due to the fact that in the known constructions, above all, the stator of the drive motor in which the major part of the heat generated during operation occurs, is not adequately thermally decoupled from the spindle housing.
The object underlying the invention was, therefore, to eliminate this deficiency in the prior art as fully as possible, and departing from a motor spindle cooled by a coolant for a machine tool and comprising a workpiece spindle and a three-phase motor having a rotor surrounding the workpiece spindle axis, concentric with the workpiece spindle axis and rotation-wise fixedly connected to the workpiece spindle and a stator surrounding the rotor and concentric with the rotor, further comprising a spindle housing accommodating the three-phase motor and having the workpiece spindle mounted therein for rotational movement about the spindle axis, and also comprising coolant channels surrounding the stator, this object is accomplished in accordance with the invention in that --in section through the three-phase motor perpendicularly to the spindle axis--at least one inner coolant channel enclosing the stator at least to a major extent and at least one outer coolant channel similarly enclosing the stator at least to a major extent are provided, the outer coolant channel lying--in relation to the spindle axis--outside the inner coolant channel in the radial direction, and in that a coolant inlet is connected to a first end of the outer coolant channel, the second end of the outer coolant channel to a first end of the inner coolant channel and the second end of the inner coolant channel to a coolant outlet.
In the coolant system design according to the invention, the stator of the drive motor is thermally insulated from the spindle housing (this could also be the headstock of the machine tool) by the outer coolant channel. In this connection, it has to be borne in mind that it is the coolant that has not yet heated up or at most to an insignificant degree that is conducted in the ou
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Grossmann Walter
Link Helmut Friedrich
Howell Daniel W.
Index-Werke GmbH & Co. & KG Hahn & Tessky
Kirkman Christopher
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