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AssigneeNone recorded
InventorsVittorio Giardino, Loris Giardino
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An electronic control apparatus for internal grinders wherein, with the workpiece fitted on slippers, a hole diameter gauger is provided. The gauger consists of two symmetric, linear transducers, by which the positions of both ends of a diameter are separately sensed. A measuring instrument is provided along the axis of wheelhead unit feeds, referred to the diamond truing position. The above defined electronic, control apparatus includes means by which the displacements of rotation axis from one, to another workpiece, caused by the changes in the diameter of same piece, are obtained from the signals of the two linear transducers. An analogic inverter, by which the sign of signal of one of the transducers is reversed, and an analogic adder, in which said reversed sign signal and the signal of other transducer are added with one another are provided. Means are provided for deriving the position of truing diamond relative to workpiece (considered along the axis of feeds), from the gaugings of hole diameter, from the traversings of grinding wheel, and from the traversings of workpiece rotation axis. Means are included for the utilization of results of the measurements and of the position, for controlling the operating cycle. When the workpiece is not fitted on slippers, the means as herein before stated, for deriving the displacements of rotation axis from one, to another workpiece, caused by the changes in the O.D. of same piece, from the signals of the two linear transducers, are not included in the electronic control apparatus.
An electronic control apparatus for internal grinders applied to a grinding machine where the workpiece is placed on slippers, and fitted with a hole diameter gauger, of the type in which the positions of both ends of a diameter are separately sensed by two symmetric, linear transducers, and with a measuring instrument acting along the axis of wheelhead unit traverses, referred to a trued position, the apparatus comprising means for deriving displacements from one workpiece to the next workpiece of the axis of rotation, caused by differences in their respective outer diameters from signals from said two linear transducers, said means for deriving comprising an analogic inverter, wherein the sign of the signal delivered by one of said transducers is reversed, an analogic adder wherein the sum is formed of said signal having a reversed sign and of the signal delivered by the other one of said transducers;
In an electronic control apparatus for interal grinders applied to a grinding machine where a workpiece is to be placed on slippers and which includes gauging means for sensing positions of both ends of a diameter, the gauging means including two symmetric, linear transducers, and means responsive to output signals from the two transducers;
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Control or regulation of feed movement: according to the instantaneous size and the required size of the workpiece acted upon
While the tool acts upon the workpiece: compensation of tool-deflection due to temperature or force
According to the instantaneous size and required size of the workpiece acted upon, the measuring or gauging being continuous or intermittent:…
Details, components, or accessories for machine tools
Term ended 23 Sep 1997 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
As well known, in a grinding machine, the wheel is cyclically dressed, with simultaneous restoring of its shape by the so called diamond truing; the position of cutting surface of inoperative grinding wheel, relative to machine is determined by the position of diamond and by the traverses of wheelhead unit.
The surface which is being ground is identified by its rotation axis and by the diameter, and in the course of grinding operation, it is tangent to wheel cutting surface; however, the position of operating wheel differs from that which would be taken by the inoperative wheel, due to the presence of substantial elastic deformations, caused by the pressure of wheel against the workpiece, and that are usually, though improperly called "extension flexure" (which is actually a part only of such deformations).
With the method based on the grinding wheel control ("size-matic"), the gauging of hole depends on the reproducibility of hereinafter stated factors: (a) The position of truing diamond relative to workpiece; (b) The traverses of wheelhead unit; (c) The final extension flexure; (d) The wear of grinding wheel from the last diamond truing and the end of grinding operation. A periodic control of workpieces, with possible corrections, is required by the point (a), due to the action of slow drifts, caused by the wear and by thermic motions while, when the workpiece is fitted on slippers, the method becomes quite inapplicable, since any difference in the outer diameter should directly be reflected on the diameter of hole. The point (b) may be considered as complied with in the properly designed machines. By the point (c), final flexures so small are required, that the variations thereof may be neglected, and thus very long times for the extinction of ray of sparks. By the point (d), a diamond truing is necessary before of finishing pass.
FIG. 1 shows, diagrammatically by way of an example, certain of the essential items which contribute to the grinding operation.
FIG. 2a shows, in a partial block diagram, the control apparatus in question related to an internal grinder in which the workpiece is not mounted on shoes.
FIG. 2b shows, in a partial block giagram, the control apparatus in question related to an internal grinder in which the workpiece is mounted in shoes.
Before describing the embodiments of the present invention, a few brief remarks relating to the grinding art in general appear to be in order, reference being made to some of the above-mentioned figures.
As shown in FIG. 1, the grinding wheel 2 cannot operate in any internal grinder without exerting a thrust F against the inner surface of the workpiece 1; a grinding wheel that glides over the surface being machined does not remove any material.
The thrust F generates a tangential thrust T and thus the grinding wheel 2 is subjected to a force R resulting therefrom, which causes a flexure on the part of the wheel spindle P (see FIG. 13). The flexure, with the grinding wheel under stress (i.e. in operation) is never negligible in an internal grinder, despite the opposite being the case in an external grinder.