US2835227A

US2835227A - Hydraulic rotary distributor and its application to operating jacks for work-holdersof machine-tools

Info

Publication number: US2835227A
Application number: US413891A
Authority: US
Inventors: Louis J M Gamet
Original assignee: LA PRECISION INDUSTRIELLE
Current assignee: LA PRECISION INDUSTRIELLE
Priority date: 1953-03-09
Filing date: 1954-03-03
Publication date: 1958-05-20
Anticipated expiration: 1975-05-20
Also published as: GB761157A; FR64947E; FR1075565A; DE1018696B

Description

May 20, 1958 L, J 'M, GAMET 2,835,227

HYDRAULIC ROTARY DISTRIBUTOR AND ITS APPLICATION TO OPERATING JACKS FOR WORK-HOLDERS OF MACHINE-TOOLS Filed March 3. 1954 3 Sheets-Sheet 1 lanlllalllllIlllllllllallllllnlllllllll y .lltllllflllllrl IIlllllllllnlllllilllllld ...1

RLM

May 20, 1958 L. J. M. GAMET 2,835,227

HYDRAULIC ROTARY DISTRIBUTOR AND ITs APPLICATION TO OPERATING JACKS FOR WORK-HOLDERS OF MACHINE-TOOLS Filed March 3. 1954 3 Sheets-Sheet 2 fai- :LL z

\ "if A May 20, 1958 l L, J, M, GAME-T 2,835,227

HYDRAULIC ROTARY DISTRIBUTOR AND ITS APPLICATION TO OPERATING. JACKS FOR WORK-HOLDERS OF MACHINE-TOOLS Filed March 3. 1954 3 Sheets-Sheet I5 www United States PatentfHYDRAULIC ROTARY `lDISTRIBU'lOR AND `ITS APPLICATION TO @OPERATING JACKS `FR WORK-HOLDERS F MACHINE-TOOLS Louis J. M. Garnet, Bougival, France, assignorto `La Precision `Industrielle (Societe Anonyme), Rueil-Malmaison, `Seine-etise, France, a French company Application March 3, 195.4, Serial No. 413,891

Claims priority, application France` March 9, 1953 2 Claims. (Cl.` `121---3 8) For the operation of the work-holders orrnandrels of machine-tools, it has already been proposed to `use l-lydraulic` or pneumatic jacks mounted on the: spindle of the machines on the side-opposite to the chuck and actuating,` through the medium of the workspindle, 1an Operating member of t. the said chuck.

As this spindle and `this operating member rotate during the operation of the jack, the most simple solution; consists rin usinga` jack which is also rotating and to supply this jack b-yI means of arotary distributor.

However, the known types of rotary distributor have a nnmberof `drawbacks essentially due to the friction of the fixed portion of the distributor against the rotating portion. This frictionVin fact, prevents theruse of high `fixed channel ofliquid under pressure with a cavity provided in a rotating member, is characterised in that the said xed channel leads into an annular groove formed in a xed collar of cylindrical internal shape, which surrounds with a small clearance the said rotating member, the latter being provided with an opening communicating with the said cavity and having its outlet in the plane of the said groove, the` said collar or ring member being Vcentered with respect to the rotary member by means of roller bearings arranged near its extremities, the whole assembly being enclosed in a fluid-tght casing serving as aliquid collector.

In such a distributor, therefore, there exists no frictional contact between the rotating portion and the fixed portion since the, rotating member does not actually touch the internal wall of the ring member. The speed of rotation vis therefore notjlimited and no wear` is to be feared,

the leakage which takes place `through the small clearancebetween therotating` member and the ring remaining constant over a very long period of time. This leakage, the amount ofwhich may be determinedbeforehand,v `is utilised, when the liquid employed is oil, for thelubrication and the cooling of the roller bearings on l which the ring member `is, supported. The oil is thereafter collected and recovered from the enclosing casing. `It will be noted' that the rotating member may passright through this casing `without causing any difficulty, since lthe casing only `contains liquid expanded down .to

.atmospheric pressure and the rotating joints between the casing and the rotating member do not, in consellquence, present any diiliculty of construction.

lln` one form of` embodiment of the invention, the rotating member is an annular hydraulic jack rotating cwith `the-spir1'dle ofa machine-tool, the jack comprising a cylinder and piston of which one is rigidly fixed to .rislc of internal fracture.

`the intentional oil leakage from the distributor, but also the parasitic seepage which may be `produced after a long period at the periphery; of the cylinder,- by reason of the centrifugal force which is additive to the internal pressure ofV the oil which it contains. Fluid-tightness is thusA ensured, which enables the jack `according to the `invention torbe arranged on the exterior of a machine, `vt'itl1ontfearof loss or throwing-eut of oil.

Due to its thermal conductivity, this casing ensures in addition the dissipation to the outside atmosphere of the heat developed by the internal friction `ot the oil `inside the distributor, and it is with advantage `provided-with tins for this purpose.

Lastly, this casing provides safety against risk of injury to the user by rotating parts and against the l'n consequence, the dimensions of' the walls of the casing and those of the cooling tins are chosen so` as to. .give the casing the `necessary rigidity.

In the distributor in accordance with the invention, `the leakage of oil between the rotating member and the ring depends essentially, for any given clearance between these` two.V parts, on `the viscosity` of the oil used. In` practice, the oil` flowing throughs this clearance forms two lms, one of which adheres to the ring and the Vother tothe rotatingmember. If` the total thickness Vof these films is less than the clearance, no flow of liquiditakes .-.pl.ace;.this is` especially the case when, at the time of starting up,.the oil which is at the. ambient temperature iswhghly Viscous. The width of the space betweenthe two :which determines the leakage cross-section,

thus bever-y small and the flow of the, leakagetof o il is finally, for a given` clearance, proportionalto the `length of the.;` periphery of the rotating member and `not `.to` the` total cross-Section `of the clearancelbetweenthe rotating member andthe ring. As, on the other hand, these-latter parts cannot come -into Contact with each other, it Vis possible toconstruct, even,.for high speeds of rotation, distributors of large diameter which, in

particular, ,enable a large free passage to 4be provided along the `axis of these distributors.

In addition, one single distributor may comprise `a number of channels for the oil under pressure and of distribution Agrooves which enable a `number of servomotors or hydraulic motors to be fed from thesame t rotating member.

yilhese servo-motors may be, `for example, la jack .intended ,to eifach `whilst the spindle is continually rotating, the ejection ofthe machined work `from the work-holder when completed, or `the, introduction of the work to be machined in the Work-holder. The hydraulic `motors may drivetools which carry out a supplementary machining operation on the partei the work held in the workgholderduring the rotation of this latter fand of thework-piece which it carries.

l,Ina more general way, `the distributor `injaccordance with the ,invention may `be, used to direct the oil under ,pressureyprodnced froman external source, .into a chantwo parts does notincrease due to wear, and in conseweturedoes not varyin course of time;

qlltmeel the jleakigetof oil provided forsduring manufac- 3 of the oil itself, and this cooling and lubrication are especially effective when they are most necessary, namely when the distributor is in operation;

The internal passage formed in the spindle of the ma chine by the machine constructor is left free, the internal diameter of the distributor being chosen to be equal to or greater than the diameter of this passage;

Finally, by virtue of the enclosing casing, the leakages, of oil, that is to say the pre-determined leakage and, eventually, other seepages of oil, are recovered.

The description which follows below with respect to the attached drawings (which are given by way of example only and not in any sense by way of limitation) will make it quite clear how the invention may be carried into effect, the special features which are brought out either in the drawings or in the text, being understood to form a part of the said invention.

Fig. l is an axial cross-section of a jack provided with a distributor in accordance with the invention, mounted on the spindle of a machine-tool. This ligure corresponds to the cross-section line I-I of Fig. 2.

Fig. 2 is an end view of the jack shown in Fig. l.

Fig. 3 shows in axial cross-section a further form of embodiment of the invention. This cross-section corresponds to the line III-III of the plan view of this jack shown in Fig. 4.

Fig. 5 shows in axial cross-section an arrangement of the spindle of a machine-tool comprising a distributor provided with a number of oil supply lines.

Fig. 6 shows a separate distributor in axial cross-section.

In all these figures, the same parts are given the same reference numbers.

On the end of the spindle 1 of a machine-tool, is xed, by means of screws 2, the cover 3 of the cylinder 4 of an annular jack which thus rotates as a whole withvthe said spindle. The annular piston 5 of this jack is xed to the tube 6, which slides in the spindle channel, by means of a threaded collar 7. The fluid-tightness of the compartments located on each side of the piston 5 in the cylinder, and the fluid-tightness of the piston itself, are ensured by

packing rings

8 and 9 respectively.

The oil may be supplied to each of these compartments through the medium of a rotating distributor which comprises a rotating portion lconstituted by a hollow cylinder or journal 4a, which is an extension of the jack cylinder, and a iixed portion formed by a ring member 1t) which surrounds the journal 4a.

Annular grooves

11 and 12 are formed in the ring member 10, into each of which grooves discharges a

nozzle

13 and 14 respectively which are supplied with oil under pressure.

The left-hand compartment of the jack communicates with the groove 11 through the duct or channel 15 drilled in the cylinder 4. The groove 12 communicates with the right-hand compartment of the jack through the bent duct or channel 16, which is also drilled in the cylinder 4.

The rotating part of the distributor is centered in the ring member carried on the casing 17, which encloses the whole assembly, by

roller bearings

18 and 19 which are located on each side of this ring; the ring is also supported with respect to the portion 4a in such a way that a very narrow space (of the order of 1/100 of a millimeter) is maintained over the whole periphery of the portion 4a between this portion and the ring.

ln order to ensure a perfect concentricity between the ring 10 and the rotating distributor 4a, whilst at the same time maintaining the width of the small clearance which separates them in spite of variations in temperature due in particular to heating up during use, the same material is preferably employed for the lnanufacture of these two portions and the cross-sections of the two portions are approximately equal. In addition, by reason of the high degree of precision required, the roller tracks 4 of the cylindrical rollers are preferably machined directly in these two portions, which avoids the troublesome eccentricities of the bearing rings.

The enclosing casing 17 is closed by

separate covers

20 and 21, the bored-out portions of which are applied to the rotating portions through the intermediary of uidtight packing rings 22 and 23. These packing rings, as shown in the figures, are preferably simple grooves for the recovery of leakage oil, due to the fact that the oil contained in the casing is at atmospheric pressure. The only friction arising in the device is thus due to the internal friction of the oil in the distributor during operation, and this enables very high speeds of rotation to be reached without wear of any rotating part.

As is clearly apparent from Fig. 1, for example, the ring 10, which forms a part of the annular member in cooperation with the rotating member 4a to provide the annular duct between these members, substantially projects at both extremities thereof, thus providing the sufficient length of the annular duct between the

extreme grooves

11 and 12 and the corresponding end of this annular duct. This is also true of the construction shown in Figs. 5 and 6, wherein the length of the annular duct will he noted, with respect to Fig. 5, in considering the space between the

extreme grooves

29 and 12 and, as shown in Fig. 6, the

grooves

29 and 30.

At its lower portion, the casing 17 is provided with an oil-removal nozzle 24 which collects the oil from all parts of the casing. Fins 25 distributed along the surface of the casing, assist the cooling of the latter and also ensure its rigidity.

In operation, the oil under pressure supplied from one of the

nozzles

13 or 14, (whilst the other is open to exhaust) fills the corresponding groove and at the same time the space comprised between the portion 4a and the `ring 10. This deliberate and pre-determined leakage may be practically nil when the oil is cold and may rise to, for example about 2% of the oil in circulation when the machine has reached its final operating temperature.

At the extremity of this space located on the side of the nozzle which is put under pressure, this oil splashes out towards the corresponding

bearing

18 or 19 and lubricates this bearing whilst at the same time cooling it. The oil is ultimately drawn-off through the nozzle 24. Each of the bearings is thus copiously greased and cooled in turn and this ensures that the centering of the distributor is maintained.

In the form of embodiment shown in Fig. 3, the ringmember 1t) is machined in the casing 17 (it may also be separately attached to this casing) but in this case, the rings surround the cylinder of the jack which forms the rotating part of the distributor so that the

channels

15 and 16, by means of which the

grooves

11 and 12 communicate with the compartments of the jack, are very short.

In this case, the

bearings

18 and 19 are located on opposite sides of the jack itself, the periphery of which constitutes a distributor. There is obtained in this way a form of construction of the jack which is much shorter in length.

In this form, the oil-supply points in the compartments of the jack could also be provided on the faces of the latter. This arrangement is, however, objectionable hecause of the axial thrust which would thus be applied to the jack.

The embodiment shown in Fig. 5, although more complete, is similar in its general lines to that which has been shown in Figs. l and 2. It shows the Work-holder chuck associated with the annular jack and a supplementary jack inside the spindle 1.

In this embodiment, the threaded collar 7, which rigidly couples the piston 5 of the jack with the tube 6, is perforated at 7b and provided with a locknut 7a.

The work-holder chuck is of the pincet-jaw type. The

ensmsg? -whilst the tube -6 `works by lateral movement on y'the conical member 28. This gripping-memberisahollow conefprovided-with radial slots 28a. The operation of lateral movement of the pincerlmember 28 isiobtained, A

as in Lthe `case of Fig. l, `-by the -liquid conveyed under pressure througlrthe4 channels 13:and 114, by virtue of the `annular Vgrooves 11 and 12 of the ring 10, .which .com-

municate with the elbowed

passages

15 and 16 drilled in the cylinder 4. In addition, two other grooves 29 'and 30, similar to the

grooves

11 and 12, are machined in the ring 10, and the

nozzles

31 and 32 lead respectively into these two other grooves.

The groove 30 communicates, through channels 33 drilled in the rotating part 4a, with space included between the spindle 1 and the tube 6. The communication being ensured by the drilled passages 7b of the threaded collar 7, by the oritice 35 formed in the tube 6, this space communicates in its turn with the internal channel of the tube 6.

ln the same way, the groove 29 communicates through the radial channels 36 formed in the portion 4a, with the groove 37a of a closure member 37 adapted to close the extremity of the rotating portion 4a; duid-tightness on each side of this groove is obtained by means of packing rings 38.

The groove 37a communicates through the channels 39 with the interior of the tube 6, by virtue of the extension 37b of the closure member 37 on which the tube 6 is arranged to slide through the medium of the fluid-tight packing ring 40.

The piston 41 slides inside the tube 6 and is rigidly coupled to a cylindrical rod 42 which extends into the interior of the conical jaws 23, passing into this member with the interposition of the huid-tight packing ring 43.

On the work-holder side, the fluid-tightness ofthe space comprised between the spindle 1 and the tube 6 is obtained by the packing ring 44 applied against the cylindrical portion of the pincer member, the packing ring being retained by the ring 45 inside the work-holder. This ring may be put into position by virtue of the assembly of the work-holder which is in two parts, secured together by bolts 46.

The arrangement which is supplementary to that shown in Fig. 1 and which has just been described, operates in the following way:

If oil under pressure is applied to the nozzle 31, this oil passes directly into the tube 6 and forces outwards the piston 41 and therefore the rod 42, Which expels the cylindrical workpiece engaged in the chuck. Conversely, if the orifice 31 is set to discharge and the oil under pressure is applied to the nozzle 32, this oil penetrates into the space comprised between the spindle and the tube 6, and then fills the tube 6 through the orifice 35, after which it acts on the right-hand face of the piston 41 which brings the latter towards the left, at a higher speed moreover than its movement towards the right, it being supposed that the outputs of the

nozzles

31 and 32 are equal. The piston 41 comes into abutment against the extremity of the member 37b, and thus the extremity of the rod 42 located inside the chuck may itself serve as an abutment for the engagement in position of the fresh piece to be machined. To this end, the assembly formed by the piston 41 and the rod 42 may be provided with an adjusting arrangement enabling its length to be varied so as to permit of the correct positioning of the piece to be machined.

As in the previous cases, the rotating part 4a of the distributor is centered in the ring 10, carried by the casing 17 which encloses the assembly, by the

roller bearings

18 and 19 which are situated on each side of this ring, so that there is provided a very narrow clearance of the order of one hundredth of a millimeter, both along the whole length and along the periphery of the ring, between this ring and the rotating portion.

lnfoperation, :the oil un'der `pressure supplied :byany one ofzithe nozzles =13, 114, '31 .or 32,rescapes tin apart through the space `included `l'retwfeenlthe frotatingrportion and the ring of the distributorand:afterwards `serves to lubricate and cool the

bearings

18 and 19. The expanded oil is collected in thecasing "1'7 V"romwvhich litis removed through the .chanuel124. Thejointsof Vthe covers are `suiiicient ,to prevent leakages of expanded oil `outsidethe casing.

During the rotation of the assembly, the onlyfrictional effect is thus due to the internal friction of the oil in the space comprised betweenthe ring and the rotating part of the distributor, which enables very high speeds to be attained without any wear of a rotating part.

The embodiment shown in Fig. 5 illustrates that the rotary distributor in accordance with the invention, by

reason of the absence of friction, enables as many servomotors or hydraulic motors as may be necessary to be installed in a rotating spindle.

Conversely, a rotary distributor of this kind can be constructed independently of an operating jack for workholders as is shown in Fig. `6. Inthis ligure, at the end of the spindle 1, there is machined or separately added the rotating portion 4a of the distributor, the latter co operating with the ring 1G which is iixedly retained inside the casing 17; the two

bearings

18 and 19 are arranged on each side of the distributor and serve to center the rotating portion in the ring; the

channels

33 and 36 communicate with the

grooves

29 and 30 and are directed into the spindle towards the utilisation points.

In all cases, passages 47 are formed in the lower part of the ring 10 or inside the casing 17 so as to allow the return of the oil to the orice 24.

The conduits for the liquid under pressure leading to the distributor in accordance with the invention may be supplied from any particular source. lt is, however, necessary to provide in the liquid circuit filters such as will prevent the passage of solid particles, the size of which would be of the same order as the clearance provided between the rotary member and the ring, that is to say particles of about one hundredth of a millimeter.

It will, of course, be understood that modiications may be made to the form of construction which has been described above, in particular by substitution of equivalent technical means, without thereby departing from the spirit or from the scope of the present invention.

What I claim is:

l. In an actuating jack associated with the work spindle of a machine, a hydraulic pressure distributor for connecting a stationary pressure liquid supply line with chambers formed in the jack cylinder on opposite sides of the jack piston; comprising a journal fast with and extending axially from the cylinder and having a cylindrical outer wall, said journal having separate axially extending passages formed therein and communicating with the chambers, said outer wall ot the journal having axially spaced annular grooves formed therein and communi eating with the passages, a stationary ring-like member surrounding the journal and having an inner cylindrical wall radially spaced from the outer wall of the journal to provide a thin annular duct therebetween and said inner wall and outer wall extending axially beyond the grooves, said ring-like member having radial ports in communication with the grooves, said inner wall and the outer wall at their extremities being formed with confronting annular pathways, roller bearings disposed in the pathways to support and center the journal and to maintain the annular duct in the shape of a regular annulus of uniform width, said roller bearings being in constant communication with the annular duct to be lubricated and cooled by the liquid therein.

2. The combination of claim l, including a casing enclosing the stationary member and the jack and the journal and having a center annular part and opposing ends, said ends being formed with openings receiving 7 the end of the journal and the other end of the cylinder and the bounding walls of the openings having annular grooves communicating with the atmosphere for the recovery of leakage liquid.

References Cited in the le of this patent UNITED STATES PATENTS S Groene etal Feb. 11, 1936 Bradley Apr. 14, 1942 Ostergren Jan. 2, 1951 Bryant Apr. 10, 1951 Sloan etal Sept. 18, 1951 Reed Mar. 23, 1954 FOREIGN PATENTS France July 13, 1942