Turning – Lathe – Headstock
Reexamination Certificate
2000-07-03
2001-10-16
Tsai, Henry (Department: 3722)
Turning
Lathe
Headstock
C082S160000, C082S165000, C082S118000
Reexamination Certificate
active
06302006
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a machine spindle for mounting tools or workpieces.
In conventional work spindles the clamping/release function is realized either manually or by hydraulically or pneumatically actuated clamping devices, the pressure medium having to be transmitted via rotary distributors from non-rotating components to the rotating parts. Due to leakage losses, heat development and the resulting limitation in terms of rotational speed and pressure which can be transmitted, rotary distributors constitute problematic machine components. For the purpose of tool clamping, cup-spring assemblies are thus often used within the rotating spindle. Such assemblies always have to be configured precisely with respect to a specific application case because short clamping paths and large release forces have to be taken into account and do not allow flexible solutions. For the purpose of securing the machine spindle in a certain angle position, a further hydraulically or pneumatically actuated device is required on the work spindles.
Published German Patent Application No. DE 43 25 593 A1 describes a machine spindle which, due to specifically configured elements, can execute clamping/release functions by way of the spindle drive itself. However, the functioning principle results in a disadvantageous rotation of the clamping mount during the clamping/release operation.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a machine spindle which overcomes the above-mentioned disadvantages of the heretofore-known machine spindles of this general type and which is suited as a work spindle of machine tools and robots in which functions such as rotation, positioning and securing in a certain angle position, clamping and releasing as well as the gripping of tools or workpieces are combined in as compact a unit as possible with the smallest possible number of functional elements.
With the foregoing and other objects in view there is provided, in accordance with the invention, a machine spindle for mounting a tool or a workpiece, including:
a rotationally-fixed spindle housing;
a two-part, central spindle shaft having a first spindle-shaft part and a second spindle-shaft part;
the first and second spindle-shaft parts being rotatable with respect to one another, being axially non-displaceable with respect to one another, and being disposed coaxially with respect to one another;
the first spindle-shaft part having a mounting device for mounting one of a tool and a workpiece;
the two-part, central spindle shaft having spindle ends, respectively formed by the first and second spindle-shaft parts, the two-part, central spindle shaft being mounted as a unit, at the spindle ends, in the rotationally-fixed spindle housing;
an integrated, task-dependent clamping/release mechanism operatively associated with the first and second spindle-shaft parts, the integrated, task-dependent clamping/release mechanism being actuatable by rotating the first spindle-shaft part relative to the second spindle-shaft part; and
an angle-position-controlled spindle drive connected to the second spindle-shaft part.
In accordance with another feature of the invention, a further angle-position controlled spindle drive is connected to the first spindle-shaft part. A position sensor is disposed in the spindle housing, the position sensor permanently sensing respective angle-of-rotation positions of the first and second spindle-shaft parts. A process computer is connected to the position sensor, the process computer monitoring whether a predetermined clamping/release status is maintained, and, when a high clamping/release moment is introduced, the angle-position controlled spindle drive on the second spindle-shaft part assisting the further angle-position controlled spindle drive on the first spindle-shaft part, as a parallel drive, with a sufficient distance from the clamping/release moment.
In accordance with a further feature of the invention, the integrated, task-dependent clamping/release mechanism is a self-locking or self-inhibiting clamping/release mechanism.
In other words, the machine spindle for tool or workpiece mounting according to the invention, has a two-part, central spindle shaft which, by way of its two spindle-shaft parts, which can be rotated in relation to one another but cannot be displaced axially in relation to one another, is mounted as a unit at both spindle ends in a rotationally fixed spindle housing. The two spindle-shaft parts of the spindle shaft are provided coaxially, and the spindle shaft is mounted in a stable manner as a unit. An integrated, task-dependent clamping/release mechanism can be actuated by rotation of the first spindle-shaft part relative to the second spindle-shaft part. The machine spindle is assigned at least one angle-position-controlled spindle drive, and the second spindle-shaft part, without a tool or workpiece mounting, is connected to the spindle drive.
During clamping and release via the spindle drive, the necessary supporting function or counteracting function takes effect, depending on the respective configuration, either as indexing or clamping of the spindle, or it acts in the form of a second controlled drive in that a clamping/release operation is possible at any desired rotational speed for the tool or workpiece mounting (including rotational speed 0). For this purpose, the central spindle shaft is provided in two parts, with the result that, by rotation of the two spindle-shaft parts relative to one another, a clamping/release mechanism, which differs from case to case, is actuated.
The spindle-shaft unit is mounted in a stable manner as a whole either in that the first spindle-shaft part, which has a tool or workpiece mounting, is mounted in two bearing locations in an ordered manner in the rotationally fixed spindle housing and the second spindle-shaft part, for its part, is mounted indirectly and coaxially on or in the first spindle-shaft part or in that the first spindle-shaft part, with the tool or workpiece mounting, is mounted directly in the spindle housing, in a first bearing location, only on the side with the tool or workpiece mounting and has the other part-shaft end mounted indirectly in the second spindle-shaft part, wherein the latter, for its part, is mounted directly in the spindle housing only by way of the second bearing location and, in the process, is supported by the first, stably mounted spindle-shaft part in that the latter extends, within the second spindle-shaft part, into the second bearing location or else into a very close proximity thereof.
According to a preferred embodiment of the invention, the two-part spindle shaft is enclosed coaxially by a ring which can be displaced axially between two end positions and, in one axial end position, connects the two spindle-shaft parts to form a spindle shaft, which acts as a unit, for the normal operation as machine spindle and, in its other axial end position, connects the first spindle-shaft part, with the tool or workpiece mounting, in a fixed manner to the non-rotating spindle housing, the second, non-secured spindle-shaft part being coupled exclusively to the clamping/release mechanism which is used in accordance with a respective given task and can actuate the clamping mechanism specifically via a controlled spindle drive connected to the spindle-shaft part.
In a further advantageous embodiment of the invention, the first spindle-shaft part, with the tool or workpiece mounting, is connected by the two-part spindle shaft to a dedicated angle-position-controlled spindle drive, by which the first spindle-shaft part can be driven separately, the separate activations for the two spindle-shaft parts being coupled via axis interpolation.
The two spindle-shaft parts are provided within the spindle-shaft unit in an axially stationary manner such that they can be rotated in relation to one another, with the result that reaction forces can be absorbed by the axial connection during the clamping/release operation.
The c
Greenberg Laurence A.
Lerner Herbert L.
Stemer Werner H.
Tsai Henry
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