US2207312A - Supporting, cooling, and lubricating means for high-speed shafts or spindles - Google Patents

Description

Patented July 9, 1940 SUPPORTING, COOLING, AND LUBRICATING MEANS FOR. HIGH-SPEED SHAFTS OR SPINDLES Mario Consigliere, Genoa-Nervi, Italy in December 17, 1930, Serial No.- 240,475

In Italy December 21, 1937 s 6 Claims. (01. 51 -166) This invention relates to anv apparatus for Applicatio grinding small bores.

It is known that the grinding of small bores -still meets with difflculties the first of all being 6 the high angular speeds required for such work.

In fact, for a good production and a careful finishing it is necessary that the peripheral speed of the grinding tool be kept between 20 and 30 metres persec. For instance, for grinding a bore having a diameter of 6 mm. by using a grinding wheel having a diameter of 5 mm.. by a peripheral speed of 25 m./sec., the angular speed of the tool must reach 100,000 revs. per min. Further, if the bore has a considerable depth, and at present such depth equals in many instances ten times the'diameter of the bore, it isnecessary to employ very long and fine spindles. Always considering a bore of 6 mm. the spindle should have for such depths a length of. about 60 mm. and adiameter of not over 4 mm. in order to bear at its end a grinding wheel having a diameter of 5 mm. When considering that the total amount of overhanging from the bearingcould not be less than 70 mm. the theoreticalcritic speed of such a spindle would be of 34,000 revs. only, i. e. almost one-third of the angular speed required for agood operation of the grinding wheel.

ing from those now in use, fully answers the different requirements that I am going to shortly carrying spindle driven at very high speeds, have point out hereinafter.

The rotating part must be very light guided by multiple bearings and have a modulus of resistance that is higher than thatv overhanging rotating-solid spindles now in use.

Fll

rther it is the bearings.

Such problems and still some other ones connected with the construction of devices for-the grinding of small bores having a grinding wheelbeen brilliantly resolved in the manner thatshall clearly a'ppearfrom a practical embodiment which is shown by way of a non-limiting example in the annexed drawing, in which:

Fig. 1. is an axial section of the forepart of a spindle for grinding small bores, based principle of the present invention;

upon the Fig. 2 1st. reduced section of the rear part 01' same spindle; I

Fig. 3 is a front view on enlarged scale of the same spindle. a

The spindle shown in the drawing is designed for the grinding of small bores. It is known that as a grinding wheel must have a peripheral speed of 20 to 30 meters per sec. and when grinding bores having a diameter of less than 1 cm., by employing a grinding wheel having a diameter ofsay 5 mm., the spindle must turn at 100,000 revs. p. min.

At such an exceedingly high speed, and even at a substantially lower number of revolutions, it is practically impossible to provide for an 3 efilcient cooling by the ordinary means. and also the lubrication appears practically impossible by the usual means, as an oil film of a certain thickness practicallyacts as insulating means and being strongly laminated contributes towards an increase of'friction.

According to the present invention the above inconveniences areovercome as follows:

At least one of the rotation bearings of spindle V and in this instance the outer end bearing X of the shaft, has a perfectly adjustable clearance and is provided with longitudinalgrooves, through which a current of cooling fluid having leached the parts rotating at high speed is discharged.

Said fiuid, generally consisting of compressed air, isconvenlently oiled or otherwise greased,

before it reaches. the rotating parts, by causing it to pass through a felt, pad F or other porous diaphragm imbibed with oil or like lubricating means. In the present instance the imbibing of felt F with oil is obtained by causing a part of said felt to dip'into an oil chamber I3.

, By way of example I am going to describe in the following an improved tool for the grinding of small bores, constituting a considerable improvement-over all like tool and embodying the above principles, though it' is understood that the same system can apply to any tool having -a spindle or shaft, driven at high speed either by a turbine wheel, as in the present instance,

.. block I is slidably mounted. The block I has at its periphery a number of axial grooves which, together with the adjacent walls of easing H,

define conduits 5 m the passage of fluid.

In the fore part of block I a turbine wheel 0 is mounted, having a projecting hub 6 mounted on convenient bearings N-N' acting as rotation and thrust bearings. Hub 6 is axially bored and extends through the bottom of a cup-shaped part M abutting on oneside against the outer race of bearing N and on the other side against a screw threaded axially bored disk. L, through which therefore the axial position of bearings N-N' may be registered. Block I is fitted at its outer end with an annular disk P carrying nozzle 1 in communication with air duct and arranged in such a manner as to discharge the air through the turbine wheel 0 and to enact on the latter an inward thrust, in the direction of. bearings N-N. The outlet of air from the turbine wheel to the exterior is effected through chamber 8 of block I and port 9 of easing H.

To the outwardly projecting threaded hub part 6' of turbine wheel 0 the spindle V is fitted by means of an inwardly flanged nut T, bearing against the abutment washer 10 of spindle V. Spindle V is rotatably fitted in bearings U and X. Bearing U is fitted within a cavity of fianged disk member H having as outer central extension the supporting sleeve W. This sleeve is bored axially, but in the present case, where a boring spindle is concerned, an eccentric bore, as shown in Figs. 1 and 3,.should be preferred. The outer end of the spindle bore is flared to receive the plug-like outer bearing X having, like the corresponding outer part of the spindle a preferably conical bore and is provided with longitudinal or also helical (Gleason) grooves to enable the refrig- I block I can be registered by means of screw-shaft D under theaction of a spring C, and which'cari be shifted axially along the outer annular chamber ofcasing H by means of a screw-sleeve l2, abutting against a plug-like closure member E fitted to the end of casing H. a

By the axial shifting of the shaft D and of the block I, the position of spindle V within its supporting sleeves W can be registered. In consideration of the fact; that the outer end of the spindle is conical, it is apparent that by; axial shifting of said sleeve the clearance space between the outer end of spindle V and its bearing X can be exactly registered. a

The annularchamber I1 is filled at its lower part with oil. This chamber is formed by insert- .ing co-axially with casing H a pair of flanged sleeves I l-I4; between which afelt pad, F is inserted, so as to dip in the oil of chamber l1. Sleeve H is fittedon an air-inlet nipple G on which a-pressure spring 'A is arranged.

A portion of the pressure air is led through port IS in the upper part of chamber I1, and

-is cooledand deposits any eventual excess of oil.

A part of said oiled air is discharged through the axial bore of hub 6 of the turbine wheel and the axial 'bor 2| of the first part of spindle V and cross bores 22 of said spindle. From said cross bores it is discharged between the spindle V and its supporting sleeve W leaching these parts throughout their length and is led out through the longitudinal grooves of bearing X and cools the grinding wheel Yand blows out the dust of grinding.

Another portion of the air from chamber 20 is led through a filter through the bearings N-N' and to the exterior through part 9.

Due to the :fact that this air does not carry an excess of oil, the grinding wheel and other rapidly rotating parts do not become exceedingly work is performed more facility spindle. V and sleeve W, as well as to angularly adjust sleeve W in connection with the nature of work to be performed, all due to the above described mounting.-

- From the preceding it is' 'apparent that the new spindle represents a substantial improvement over the tools of this kind hitherto known.

in fact, due to the improved construction and arrangement of the parts and especially-of the turbine wheel and to the cooling and lubricating means, angular speeds as high as 100,000 R. P. M. and more are possible, while keeping the working parts substantially cool.

It is also apparent that'the present invention is not confined to the special construction here illustrated by way of anexample.

- I claim: f

1. An abrading tool comprising in combination: one casing, a block slidably arranged upon said casing, a turbine wheel having an axially bored hub fitted within said block and rotatably mounted on rotation andthrust bearings; a nozzle carrying disk fitted at the end of said block, with noazle blowing against the turbine wheel, a discharge chamber provided within said sliding block and in communication with an outlet port of said casing, a spindle having abutment means mounted within the end of the bore of the turbine hub, a screw-threaded flanged nut coacting with the turbine wheel hub. and abutment means of the spindle, for keeping the spindle in position; a flanged disk fitted at the end of said casing, an overhanging sleeve member integral with said disk and projecting outwardly, through which the outer part of the spindle is passed, a

pair of bearings for the spindle at both ends of said sleeve, grooves cut through the inner surface of the outer'bearing, an air duct axially traversing the rear part of said spindle and with a' transverse opening near the inlet end of saidoverhanging sleeve; means for feeding pressure fluid to the turbine wheel and means for feeding -oiled air through the turbine bearings and along the bore of turbine hub, from the rear part of spindle, as well as along the sleeved outer spindle surfaces and, through the grooves of the outer bearing, against the abrading ,or grinding ,wheel.

3. An'abrading tool according to claim 1, in

which the outer end of the spindle and its bearing are conical and comprising further means for enacting an axial sliding of the spindle-carrying block; means for shunting one part of the air admitted to the turbine wheel through an oiled pad; an expansion chamber for the oiled- 4. An abrading tpol comprising in combination an action turbine wheel mounted on rotation and thrust bearings; means for feeding air to said turbine wheel so as to rapidly rotate same as well as to impress on the same an axial thrust in the direction of the thrust bearings;. a spindle fitted on said turbine wheel, bearings at the ends of said spindle, means for feeding oiled air through those parts of the turbine wheel bearings extending along the spindle and between the spindle and its end bearing, an eccentrically bored, overhanging sleeve enclosing and stiffening the overhanging part of the spindle; a grinding wheel fitted at the free end of said spindle and a screw keeping this grinding wheel in place.

5. An abrading tool, according to claim 4, wherein an outer casing'is provided and divided into two co-axial longitudinal sections, one of which containingthe ducts for the admission of air, and the other the means for axially register- -ing the turbine wheel and spindle carrying block as well as an oil-reservoir and a pad inserted in the said oil reservoir and extending through the passages for the cooling air to be oiled for lubricating purposes. 7

6. An abrading tool according to claim 1 which pressure through a pad constantly imbibed with oil.

MARIO CONSIGLIERE.

further comprises means for leading air under

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