Abrading – Abrading process – Roll – roller – shaft – ball – or piston abrading
Patent
1997-06-20
2000-03-21
Eley, Timothy V.
Abrading
Abrading process
Roll, roller, shaft, ball, or piston abrading
451 51, 451 58, 451 57, 451 61, B24B 100
Patent
active
060396342
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
Background of the Invention
The invention is related to a method and a device for finishing hardened workpieces.
Workpieces made of steel are regularly premachined by turning, drilling and/or milling in their non-hardened state and hardened only afterwards. In order to be able to compensate dimensional changes and warping occuring during the hardening, the workpieces are premachined leaving an overmeasure, which is removed by grinding during the following finishing of the workpiece in the hardened state. During the internal grinding of bores the grinding tool is advanced into the bore of the workpiece which rotates about the spindle axis with a protruding grinding spindle, and the grinding tool is advanced perpendicular to the axis of rotation of the grinding tool against the bore wall to be machined. In this position, the grinding tool is displaced oscillating axially and brought to the feeding measure in the perpendicular feeding direction. The feeding is performed in steps until the final measure is achieved. The external grinding or the plane facing of workpieces is performed correspondingly, wherein the feeding movement is always performed perpendicularly with respect to the surface until the final measure is achieved and the oscillating movement is performed in a parallel direction. These processes are usually controlled numerically.
Grinding processes are very time consuming and therefore expensive. This is true especially for the internal grinding of relatively small bore diameters.
Based on this, it is the object of the invention to develop a method and a device of the type described above, with which a considerable time saving during the finishing of hardened workpieces may be achieved.
SUMMARY OF THE INVENTION
The solution according to the invention is based on the idea that a considerable part of the overmeasure may be removed by hard-turning in a much shorter time than by grinding and that only in places with correspondingly high demands with respect to the precision and surface quality the finishing is performed with a corresponding small rest removal by grinding. In order to achieve this, it is proposed according to the invention that before the grinding process a lathe tool is exchanged into a coaxially aligned position with respect to the workpiece spindle and/or the rotationally symmetrical workpiece surface to be machined in place of the grinding tool, the lathe tool being rotated about an axis which is aligned with respect to the axis of the workpiece spindle and being advanced axially in the direction of the workpiece while effecting a machining which removes part of the overmeasure. In this, it is essential that the hard turning and grinding are performed during one and the same clamping of the workpiece.
The grinding tool and the lathe tool are advantageously rotated about a common shift axis which is perpendicular to the momentary tool axis and to the axis of the workpiece spindle, and they are alternatively aligned in the direction of the workpiece spindle.
According to a preferred embodiment of the invention it is provided that the rotational drive of the workpiece spindle is switched off during the rotational machining. Due to the relatively high masses which have to be moved and the small cutting forces transferred to the workpiece, the workpiece spindle can remain unbraked during the lathing process and be slowly taken along in the direction of rotation without disadvantages. It is basically possible, though, to brake the workpiece spindle during the lathing operation or to lock it against rotation using simple means. Conversely, it is also possible to work with a fixed lathe tool and to rapidly rotate the workpiece using a correspondingly designed spindle drive. Depending on the requirements with respect to the precision and surface quality, 70% to 90% of the overmeasure are removed by hard turning and only the remaining rest of 30% to 10% is removed by grinding according to the invention in workpieces made of hardened steel. When taking into conside
REFERENCES:
patent: 4461121 (1984-07-01), Motzer et al.
patent: 4593444 (1986-06-01), Kavthekar
Bach Guenther
Naumann Heinz
Eley Timothy V.
Komet Praezisionswerkzeuge Robert Breuning GmbH
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