Abrasive tool making process – material – or composition – With carbohydrate or reaction product thereof
Patent
1988-03-17
1989-05-09
Schmidt, Frederick R.
Abrasive tool making process, material, or composition
With carbohydrate or reaction product thereof
51289R, 51238GG, 51103C, B24B 4904
Patent
active
048276731
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method according to the preamble of claim 1, whereby preforms (particularly, cast preforms) which have been preliminarily ground can be finalground to size; and to device according to claim 2, for carrying out the inventive method.
It is known to produce axially symmetric profiled parts by machining on a lathe, followed by grinding. When such parts are subject to stringent requirements with regard to dimensional accuracy and axial symmetry, ordinarily they are first machined (on a lathe), then possibly hardened, then pre-ground in a centerless grinding operation , and finally ground to size in one or more grinding operations.
In this grinding to size of pre-ground parts, in cases where only one end of the part needs to be ground to size and another region is subject to stringent tolerances with regard to cylindricity or conicity, the grinding must be carried out between lathe-centers (turning centers), whereby two or more grinding operations are performed, between successive pairs of which operations the workpiece is re-chucked on the grinding machine.
This multistep grinding method with rechucking is very labor intensive and time consuming. Cases where the method does not make the attainment of the desired high dimensional accuracy impossible, it makes it difficult. In any event, the method is costly.
The underlying problem of the present invention is to devise a method and device whereby the disadvantages of the customary means of grinding pre-ground parts to size are overcome, such that one can economically fabricate ground profiled parts of high dimensional accuracy and axial symmetry which are ground to size as accurately as possible in a single grinding step while mounted between lathe-centers, even when an end region of the workpiece must be included in the ground areas.
This problem is solved according to the invention by a method as set forth in claim 1, and by a device as set forth in claim 2.
The invention for the first time enables one to grind preforms to size with high dimensional accuracy and axial symmetry, by feasible and economical means, in a single operation while held between lathe-centers. Under the state of the art, such preforms would have to be ground in two or more grinding operations with two or more chuckings of the workpiece on the grinding machine. With the use of the invention, even preforms with a plurality of discontinuities (offsets) can generally be ground to size with a single chucking; and this is beneficial to manufacturing economy and the dimensional accuracy of the products.
Additional advantages and details of the invention will be apparent from the following description and from the associated drawings. In this connection, the invention will be described in more detail with reference to a special precision part which is difficult to produce, namely a nozzle needle for injection nozzles.
FIG. 1 is an enlarged lateral view of a typical nozzle needle for an injection nozzle;
FIG. 2 is a schematic plan view of the arrangement of a device on which a first step is carried out in the fabrication of the ground part, namely pre-grinding the workpiece and cutting it off from the rod;
FIG. 3 is a partial cutaway plan view of an inventive device for grinding to size the pre-ground part according to the invention, with a single chucking between lathe-centers and with a single grinding step;
FIG. 4 is a detail view, from the top, of the grinding of the apex region of the needle;
FIG. 5 is another detail view, from the top, of the grinding of the apex region of the needle.
FIG. 1 shows, in enlarged scale, a nozzle needle for gasoline fuel injection nozzles, of a configuration of such needle which can be ground to size while being held between lathe-centers, in a single grinding operation with the use of the inventive method and device. It is assumed that the preform as received has at least the precision of a centerless-ground part, or that the workpiece has been ground, i.e., pre-ground from a round steel rod in the manner described below. The enormous
REFERENCES:
patent: 4274230 (1981-06-01), Thalheim
patent: 4294045 (1981-10-01), Enometo et al.
Rachuba Maurina
Schmidt Frederick R.
Tschudin Werkzeugmaschinenfabrik
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