Metal working – Method of mechanical manufacture – Obtaining plural product pieces from unitary workpiece
Reexamination Certificate
1999-12-02
2001-10-30
Bryant, David P. (Department: 3726)
Metal working
Method of mechanical manufacture
Obtaining plural product pieces from unitary workpiece
C083S875000
Reexamination Certificate
active
06308391
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method of producing a chamfer or a keyway on a workpiece, according to which the workpiece is machined with a longitudinal feed following the course of the chamfer or groove, and to a tool for performing this method.
DESCRIPTION OF THE PRIOR ART
Machining workpiece edges to produce chamfers has so far mostly been effected by a milling operation by means of special milling cutters, which, however, involves an undesired formation of dust and a considerable amount of chips produced, and in addition only simple contours can be chamfered by means of milling. Moreover, milling cannot be performed to a certain relative cutting depth with respect to the workpiece surface, so that considerable manufacturing tolerances depending on the thickness of the material must be accepted.
Moreover, chamfering by a cutting operation by means of inclined knives or disk knives is also already known, which cutting operation requires relatively complex cutting machines.
It is therefore the object underlying the invention to provide a method as described above, which allows an economic chamfering of workpieces of an easily machinable material, in particular plastics, and leads to a perfect machining quality within close tolerances. There should also be created an expedient tool for performing this method
SUMMARY OF THE INVENTION
This object is solved by the invention in that machining is effected by a peeling operation by means of a peeling knife, whose broadside forming a cutting edge is aligned transverse to the feed direction during the longitudinal feed, and which is guided with a certain cutting depth parallel to the workpiece surface. To maintain a certain cutting depth, the peeling knife is preferably guided along the workpiece surface via a sliding block, or to maintain a certain cutting depth of the peeling knife, the distance between a reference point firmly provided on the peeling knife and the workpiece surface can preferably be measured in a contactless way by means of a laser or ultrasonic sensor and be used for adjusting the height of the peeling knife.
The peeling operation results in a clean progressive cut with a peeling depth independent of the thickness of the material, which can appropriately be maintained, in particular by means of the sliding block resting on the workpiece surface and the precise adjustment of the peeling knife with respect to this sliding block, or by controlling the height of the peeling knife in dependence on the measurement of the distance between the reference point and the workpiece surface. Peeling also produces a continuous chip without formation of dust, which chip is easy to dispose of, and apart from the actual chamfering of workpiece edges it is likewise possible to cut keyways into the workpiece surface, which allows to design surfaces with special optical effects. Since the peeling knife is rotatable about its axis and is oriented in accordance with the respective feed direction, all kinds of workpiece edges or contours can be chamfered without having to fear an impairment of the machining quality
When the peeling knife is subjected to a vibration during the peeling operation, in particular to a vibration with an ultrasonic frequency, the cutting force is reduced and higher cutting speeds can be achieved with an increased quality of the cut. In addition, the occurrence of built-up edges is prevented by a vibration superimposed on the cutting operation.
For chamfering the edges of a workpiece cut out from a starting material, the edges of the workpieces already cut have so far been milled off, which further increases the required effort. In accordance with the invention, a keyway with flanks corresponding to the chamfer is now peeled into the starting material by following the contour of the workpiece, and the workpiece is cut out from the starting material along the groove bottom, so that due to the keyway the edges of both parts to be separated from each other are chamfered at the same time, and by prechamfering the entire workpiece contour there can also be achieved an extremely precise and convenient manufacture of workpieces. Peeling the keyway and cutting through the material can be performed in successive steps, but also simultaneously in a single machining step.
When chamfered portions having the same contours are cut out from two different starting materials, and the same are alternately inserted into the recesses of the respective other starting material, which were produced by such cutting, there is obtained a special application of the inventive method for producing special floor covering plates or marquetry and the like, which provide particular decorative effects by incorporating the correspondingly different cut-outs in their recesses, where at the same rime workpieces having laterally reversed patterns are produced, so to speak.
A peeling knife substantially comprises a blade which has a cutting edge opposite a holding attachment. To be able to properly perform the inventive method with such peeling knife, the blade has a sweptback cutting edge converging to a central tip, where the cutting edge is oriented towards a broadside of the blade, the front side, and is formed between and end-face flank and a face verging into a chip recess on the broadside. By means of such blade, a keyway is peeled out of the workpiece surface, which for chamfering a workpiece is subsequently separated along the groove bottom by a separating cut and thus forms the respective chamfers for the separate workpiece parts. When using the one or the other edge portion of the sweptback cutting edge, the marginal edge of a workpiece already cut out might also be chamfered directly, and here as well the angle of the chamfer depends on the shape of the sweptback cutting edge.
When the blade has an additional cutting edge aligned normal to the front side, which additional cutting edge is formed by a rear central web of the blade and freely protrudes in an axial extension of the tip of the sweptback cutting edge, a separating cut can be performed together with the peeling cut, whereby chamfering and cutting out a workpiece are effected in one step.
REFERENCES:
patent: 4083390 (1978-04-01), Ingham
patent: 4524894 (1985-06-01), Leblond
patent: 4732183 (1988-03-01), Barnes
patent: 4791970 (1988-12-01), Walser et al.
patent: 5400843 (1995-03-01), Gonner et al.
patent: 5786266 (1998-07-01), Boruta
patent: 4205390 (1993-08-01), None
patent: 818261 (1998-01-01), None
patent: 10000282 (1998-01-01), None
Blaimschein Gottfried
Heidlmayer Franz
Bryant David P.
Collard & Roe P.C.
Cozart Jermie E.
GFM Beteiligungs und Management GmbH & Co. KG
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