US3509938A - Support device for positioning and locking a core of a centrifugal casting mould and a core adapted to said device - Google Patents

Description

May 5, 1970 M. PIERREL 3,

SUPPORT DEVICE FOR rosxwzoume AND LOCKING A CORE OF A CENTRIFUGAL CASTING MOULD AND A CORE ADAPTED T0 SAID DEVICE Filed Oct. 4, 1967 I 4 Sheets-Sheet l h vw I-w laid! IDI'ERREI,

##UIML May 5, 1970 FUGAL CASTING MOULD AND A RE ADAP'I'ED TO SAID DEVICE Filed Oct. 4. 1967 4 Sheets-Sheet 2 & N

l? Q Q g a I1 5 Q2 CD I m w ll 8 I I MM HERREA M. PIERREL 3,509,938 SUPPORT DEVICE FOR POSITIONING AND LO NG A CORE OF A CENTRI y 5, 1970 M. PIERREL 3,509,938

SUPPORT DEVICE FOR POSITIONING AND LOCKING A CORE OF A CENTRIFUGAL CASTING MOULD AND A CORE ADAPTED TO SAID DEVICE Filed Oct. 4, 1967 4 Sheets-Sheet 3 X 2% fi 923mm fi q a g 3 1: Q g; r \S :3 H" U) I: I a

l ,0 1 I N 9-" I n i I 2 I fi f I MI'M PIEIULE PIERREL SUPPORT DEVICE FORPOSITIONING AND LOCKING A CORE OF May 5, 1970 M.

A CENTRIFUGAL CASTING MOULD AND A com ADAPTED TO SAID DEVICE 4 Sheets-Sheet 4.

Filed Oct. 4'. 1967 in. M44 /E/ZREL- 7/ 7.

United States Patent M SUPPORT DEVICE FOR POSITIONING AND LOCK- ING A CORE OF A CENTRIFUGAL CASTING MOULD AND A CORE ADAPTED T0 SAID DEVICE Michel Pierre], Pont-a-Mousson, France, assignor to Centre de Recherches de Pont-a-Mousson, Pont-a-Mousson, France, a French body corporate Filed Oct. 4, 1967, Ser. No. 672,884 Claims priority, applicggitn France, Nov. 17, 1966,

38 Int. Cl. B22d 123/02; B281) 7/30 U.S. Cl. 164-292 14 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to moulds for centrifugally casting iron pipes having a socket, and more particularly to mounting and holding in position a core producing the inside shape of the socket.

It is known that moulds of this type comprise a core supported by a supporting and locking device which includes means for centering the core in the shell constituting the mould, and locking means for maintaining the core firmly in position when the mould rotates at high speed so that it can withstand the pressure of the liquid iron. The core must be rapidly placed in position before each casting. It must be perfectly centered in the shell and capable of rotating at the same speed as the latter Whereas it is mounted on a device of which at least a part con nected to the stand of the machine is non-rotatable. The core is destroyed when stripping the cast pipe and replaced subsequent to each casting.

A type of support device for positioning and locking the socket core has already been developed in the technical services of the applicant and has been described in French patent application 25,962 filed by the applicant on July 26, 1965. This type of device comprises a core carrier or breech which is flotatably mounted on a pivotable arm carried by the centrifugal casting machine.

The object of the invention is to provide a support device of the aforementioned type for positioning and locking a core in the centrifugal casting mould, this device being so improved as to ensure a smooth jerk-free operation owing to a flexible mounting inside the core support, namely a flexible assembly between a non-rotatable part integral with handling means and a core carrier which is rotatably mounted on said non-rotating part.

The invention provides a device wherein the core carrier comprises a housing rotatably mounted on said nonrotatable part and extended by at least one arm carrying at a given axial distance from said housing a ring adapted for fixing the core thereon, and is combined with an axial rolling thrust bearing which is interposed, on the axis of rotation of the core carrier, between the core carrier and said non-rotatable part and with an elastically yieldable axial compression means which act in opposition to the action of the thrust bearing for maintaining the elements in mutual contact.

Patented May 5, 1970 According to one embodiment of the invention, the core carrier is rotatably mounted on a fixed journal constituting said non-rotatable part and coaxial with the rolling thrust bearing and it comprises two rigid elements between which a sleeve of an elastomer, constituting said elastically yieldable axial compression means, is interposed.

In a modification of the invention, the axial rolling hearing is interposed between a rigid sleeve constituting the rotatable core carrier and said non-rotatable part and the elastically yieldable axial compression means is a helical spring coaxial with said rolling thrust bearing.

Further features and advantages of the invention Will be apparent from the ensuing description with reference to the accompanying drawings.

In the drawings:

FIG. 1 is a diagrammatic view, partly in section, of a centrifugal casting mould equipped with a device according to the invention;

FIG. 2 is a diagrammatic sectional view, on a scale larger than that of FIG. 1, of a device according to the invention in position for locking the core in the mould;

FIG. 3 is a partial cross-sectional view of a pipe socket core showing the means for fixing the core to its support;

FIG. 4 is a partial axial sectional view of a detail of FIG. 2 in the position before the introduction of the core into the mould;

FIG. 5 is a view similar to FIG. 2 of a modification of the device according to the invention, and

FIG. 6 is a sectional view of another modification of the device according to the invention.

(1) Embodiment shown in FIGS. 1 -4 According to this embodiment, the invention is shown to be applied to a mould consisting of a shell which is rotatably mounted inside a fixed housing A of a centrifugal .casting machine of known type.

The mould or shell M comprises, adjacent the bell or socket of the iron pipe T to be produced, a flared cavity 1 in the shape of a socket in which must be positioned a core N of sand which produces the interior shape of the bell of the pipe T. The socket 1 communicates with the exterior by way of a frustoconical flared portion 2. Interposed between the recess or portion 2 and the socket 1 is a shoulder 3.

The core N is for example of sand and resin and has a flange 4 adapted to arrest the iron and form the end face of the bell E of the pipe. The periphery of this flange 4 bears against the annular shoulder 3.

According to the invention, the flange 4 comprises on its periphery, on the side thereof opposed to the face bearing against the shoulder 3, a number of recesses 5 of the type suitable for a bayonet coupling, that is, having a notched portion a b (FIG. 3) and a shaped locking portion 0 d for example in the form of a dovetail for fixing to the core carrier constituting the rotatable part of the support device according to the invention. The latter will now be described.

The device according to the invention comprises, located on the axis XX of the mould M, an inner nonrotatable part I on which is centered an outer rotatable part II which constitutes the rotatable core carrier.

These two parts of the device will now be described.

Non-rotatable part I.It comprises a journal 6 having an axis X-X mounted on the end of the piston rod 7 of a jack V having an axis coinciding with said axis XX. This jack is adapted to exert through the support device a thrust on the flange 4 of the core N so as to apply it against the shoulder 3 of the mould M and can be mounted on the end of a pivotable core-handling arm B (FIG. 1). The journal 6 is hollow. A bore 8 for supplying compressed air (pressure of a few bars) extends axially through the journal and is connected-by way of a radial passage 9, a ring and a flexible conduit 11to a source of compressed air (not shown). Extending from the axial core 8 are radial passages 12 which communicate with the cylindrical face of the journal. Disposed in the end face of the journal is a hard plate 13 which forms part of a rolling thrust bearing and is, for example, of tungsten carbide. The journal 6 has adjacent the jack V a cylindrical flange 14 of enlarged diameter whereby it is possible, as will be explained hereinafter, to hook the rotatable core carrier to the non-rotatable part I.

Rotatable part constituting the rotatable core carrier II.--It comprises on the axis X--X and surrounding the journal 6: an outer housing 15 and an inner sleeve 16 which are interconnected by a flexible assembly comprising an elastically yieldable element 17.

The outer housing 15 is extended beyond the closed left end wall 18 thereof (as viewed in FIGS. 1 and 2) by at least one oblique radial arm 19 (at least two diametrically opposed arms are preferably provided). This or these arms carry at a given axial distance from the housing 15 a ring 20 which is centered on the axis XX. This ring is therefore rigidly integral with the housing 15 and carries as many screws 21 for fixing the core as there are bayonet-coupling recesses 5 on the core, each screw having a countersunk head co-operating with the dovetail portion 0 d (FIG. 3) of the corresponding recess 5 (FIG. 2).

The inner sleeve 16 is open at one end and closed at the other by an end wall which is in the vicinity of, but axially spaced from, the end wall 18 of the outer housing. The sleeve 16 has an axial bore 22 which is fitted on the diameter of the journal 6 on which it is rotatable. Adjacent its open end, this bore adjoins a counterbored chamber 23 having an inside diameter slightly greater than the diameter of the flange 14 of the journal on which the chamber 23 is fitted and by which it is axially retained. At the other end, the end of the bore 22 has'a cavity 24 on the axis XX for an abutment or thrust ball 25 adapted to bear against the plate 13 by a point contact therewith. Externally, the sleeve 16 comprises ribs 26 and a flange 27. The latter has, on the side thereof facing the closed end of the sleeve, a plane transverse face 28 and, at the rear adjacent the chamber 23, a frustoconical face 29.

As already mentioned, the outer housing is connected to the innersleeve 16 by a flexible mounting or assembly including an intermediate element 17. This housing has internally an axial cavity 30 having a generally cylindrical face from which inwardly extend annular ribs 31 whose minimum diameter, namely the diameter of the apex of the ribs or projections, is slightly greater than the maximum outside diameter of the sleeve .16, namely the diameter of the apices of the ribs 26. The housing 15 has at the entrance end thereof an enlarged portion to which is secured a counterflange 32 having a circular centre opening 33 which is positioned, with an axial and radial clearance, in the circumferentially extending groove 34 in the sleeve -16 between the frustoconical face 29 of the flange 27 and the transverse face 35 of the enlarged portion of this sleeve defining the chamber 23. This opening 33 is enlarged adjacent the flange 27 by a chamfered centering portion 36 which has the same conicity as the associated rear face 29, this chamfer being adapted to bear against the face 29.

The elastically yieldable element 17 is therefore interposed between the inner sleeve 16 and the outer housing 15. The element 17 is moulded from an elastomer material having in the free state the shape of a sleeve closed at one end by a flat end wall 37 and provided internally and externally with recesses corresponding to, and marrying up with, the ribs 26 and 31. The element 17 is so dimensioned as to cover the inner sleeve 16 up to the face 28 of the flange 27 and to be radially compressed 4 between the sleeve 16 and the housing 15. The end wall 37 of the element 17 is capable of being axially compressed.

The device according to the invention operates in the following manner:

(1) Holding a core N This core is positioned on the support ring 20 by presenting in front of the heads of the screws 21 the portion a b (FIG. 3) of the recess 5 and rotating the core about its axis so as to bring the locking portion c d of the recesses into engagement with the heads of the screws 21 which project from the ring 20 (FIG. 3). The support device (I-II) is then at rest. The core is still outside the mould M. It is retained on the ring 20 against which it bears through the flange 4. As the end wall 37 of the elastically yieldable element 17 has not been axially compressed or is only slightly compressed (FIG. 4), it occupies its maximum volume in the axial direction so that the chamfer 36 of the counterflange 32 is applied against the frustoconical face 29 of the flange 27. The housing 15 carrying the core in an overhanging manner is centered and axially retained relative to the inner sleeve 16 and this facilitates inserting and posi tioning the core N in the shell M.

(2) Positioning and locking the core in the mould -By supplying compressed air by way of the conduit 11 to the axial bore 8 of the journal 6, a film or layer of compressed air is created on the cylindrical face of the journal 6 between the latter and the bore 22. Owing to the presence of this film of compressed air and owing to the radial clearance between the chamber 23 and the flange 14, the sleeve 16 is freely rotatable on the journal 6. After the support device (I-II) has been returned so that its axis coincides with the axis XX of the shell M (FIGS. 1 and 2), the jack V is so fed as to engage the flange 4 of the core N in the frustoconical portion 2 and apply it against the shoulder 3 of the mould.

When this has been achieved, the jack V is continued to be supplied with fluid so that the thrust thereof exerted axially on the journal 6 applies the plate 13 against the ball 25 which transmits this thrust to the end wall 37 of the element 17. Consequently, the latter is compressed axially. In particular, the end wall 37 is crushed since the inner sleeve 16 moves axially towards the end of the housing 15. However, the frustoconical face 29 of the face 27 moves away from the centering chamfer 36 of the counterfiange 32. The latter is thus rendered completely free of the inner sleeve 16 which is only in contact with the housing 15 through the element 17. The thrust of the jack V is therefore transmitted elastically through this elastically yieldable element 17 so that the core N is firmly maintained in the housing therefor in the socket of the mould M and is capable of withstanding any thrust of the iron in the course of casting.

When the mould M starts to rotate, the core N is rotated at the same time as the mould with which it is in close contact on the shoulder 3. At the same time, the outer housing 15 and the inner sleeve 16 start to rotate since they rotate together owing to the interposition of the element 17. This is due to the effect of the ribs 26 and 31 which are embedded and thus anchored in the element 17. How- I ever, whereas the sleeve 16 rotates evenly on the journal 6 owing to the interposition of the film of compressed air and the provision of the ball thrust bearing (13-25), the housing 15 is capable of rotating in a slightly irregular manner that is, in a non-circular manner, if there are slight deformations in the mould M or the core N, owing to its flexible mounting relative to the sleeve 16. The slight movements that the housing 15 can undergo relative to the sleeve 16 in the course of rotation are elastically damped by the element 17.

Note that if in the course of centrifugal casting projections of iron occur through the spaces between the flange 4 of the core and the mould and through the inner cavity of the core, these projections of iron can travel into the space provided between the ring 20 and the housing and between the radial arms 19. The outward projections of iron can in no case come in contact with the interior of the support device (I-II) according to the invention which is perfectly protected by the housing 15.

Thus the rotating joint constituted by the journal 6, the film of compressed air on the surface of the latter, the sleeve 16 having the bore 22 and the ball thrust bearing (13-25) allows the rotation of the core N with respect to the non-rotatable support journal 6.

The ball thrust bearing (13-25) and the elastically yieldable element 17 enable a locking thrust to be transmitted to the core by the jack V so that the core is locked in opposition to the pressure of the iron, without preventing rotation of this core relative to the non-rotatable journal 6.

The flexible connection afforded by the element 17 between the sleeve 16 and the housing 15 and the ribs 26 and 31 ensures that the elements 15 and 16 are interconnected to rotate together and in the axial direction while movements of the housing 15 with respect to the sleeve 16 are allowed in the event of a more or less regular rotation of the mould.

The recesses '5 of the core N lock this core to the ring 20 in a perfect and simple manner.

In order to strip the cast pipe, the jack V is fed in the direction for withdrawing the core support, namely in the direction away from the mould M. In the course of this withdrawal, the core N crumbles and breaks up owing to the undercut portions of the pipe T. The heads of the screws 21 projecting from the ring 20 are thus completely disengaged, which permits mounting a new core for the following casting. Note that in the course of the rearward travel of the ring 20 towards the right (as viewed in FIGS. 1 and 2), the end wall 37 of the element 17 tends to resume its initial volume (FIG. 4). Consequently, the chamfer 36 of the counterflange 32 encounters the face 29 of the flange 27 while it is still in rotation.

(H) Modification of the invention shown in FIG. 5.- In this modification there can be seen the core N and the support therefor with the outer housing 15 which corresponds to the housing 15 and constitutes the rotatable part 11* of the device which is rotatably mounted on the non-rotatable part I carried by the pivotable arm B.

The housing 1 5 has a closed end in the form of an attached end wall 18 which carries a plate 13 forming part of the ball thrust bearing (13-25). The plate 13 is preferably carried by a screwthreaded plug 38 which is screwthreadedly engaged in the Wall 18 so as to enable the plate 13 to be axially adjusted in position so as to bring it in contact with the ball 25. At the open end thereof, the housing 15 has a counterfiange or inner collar 32 which is in one piece with the housing and has a centre opening 33. Large radial and axial clearances are provided between the opening 33 and the faces of an annular recess 34 formed in a non-rotatable support sleeve constituting a journal 6*.

This sleeve '6 is open at one end and closed at the other and is part of the non-rotatable part of the support device. It can be mounted on the end of an arm B for handling the core combined with axial thrust means. It can also be directly mounted in the extension of the thrust rod of a jack. Adjacent its open end, this sleeve has a head 39 adjoining the annular recess 34*, this head being very wide and having a transverse plane face 40' and a tapered face 29*. The counterflange 32 is capable of bearing against the face 40, the centre opening 33 having a diameter much larger than the diameter of the bottom of the recess 34*. The head 39 is mounted with a large radial clearance inside the housing 39. The sleeve 6 has a cylindrical bore 41 which communicates with an enlarged chamber 42 closed for example by a screwthreaded plug 43. Slidable in the cylindrical bore 41, is a tube 44 having an enlarged head 45 and a tail portion 46 of smaller diameter. The tube 42 is slidable, in opposition to the action of a coil spring 37 disposed in the chamber 42 and compressed between the plug 43 and a support washer 47 carried by the portion 46 of the tube 44. The head 45 of the latter is enlarged so as to define a hollow cavity 24 for receiving the ball 25.

The support device operates in the following manner:

(1) Holding the core. The core N is positioned on the support ring 20 in the same manner as in the embodiment described hereinbefore. The support II of the core is then at rest, the core being outside the mould M. The spring 37 is in a relatively extended state and exerts a thrust on the tube 44 through the washer 48. This thrust is transmitted through the head 45 to the ball 25 which is thus applied against the plate 13. In turn, the counterflunge 32 is applied against the flat face 40' of the recess 34 of the journal 6 by the thrust exerted on the plate 13 by the flange 35. Note that in this position (shown in dot-dash line in FIG. 5) the co-unterflange 32 of the housing 15 is centered with respect to the journal 6 by the abutment of a circular edge of the opening 33 against the inclined face 29* of the recess 34 of the journal. Thus the support ring 20 for the core N is centered with respect to the axis XX and this facilitates the introduction of the core in the mould M. Further, the housing 15 and the ring 20 are thus retained axially.

(2) Positioning and locking the core in the mould. The device (F IP) is brought onto the axis XX of the mould M and is so shifted as to engage the flange 4 of the core N in the frustoconical portion 2 of the mould and applied against the shoulder .3. The axial thrust is continued by means of a jack (not shown) and the ring 20 withstands this thrust. The spring 37 is compressed and the plug 43 bears against the end face of the portion 46 of the tube 44 to which it transmits this thrust. This sleeve transmits the thrust to the ball 25 through the head 25, this ball abutting the plate 13. But owing to the resistance of the ring 20 and consequently of the housing 15 the counterflange 32 moves away from the face 40 of the journal 6 The counterflange 32 is thus fully free with respect to the recess 34*. The rotatable housing 15 has therefore only a point contact with the tube 44 of the non-rotatable part I due to the ball thrust bearing (13 25).

Meanwhile, the core N is firmly maintained in the housing therefor in the socket of the mould M and is therefore capable of withstanding any thrust on the part of the iron in the course of casting. When the mould starts to rotate, the core N is driven in rotation at the same time as this mould owing to its close contact therewith through the shoulder 3. The support ring 20' and the housing 15 rotate with the core. Only the journal 6 and the inner tube 44 do not rotate. The ball 25 could rotate only intermittently.

Note that if the mould M or the core N have slight deformations they might rotate in a non-circular manner, that is, with slight movements relative to the axis XX owing to the provision of the large radial clearance between the centre opening 33 of the counterfiange 32 and the recess 34 of the journal 6 owing to the axial freedom of movement allowed the counterflange relative to the recess 34 as a result of the elastically yieldable compression of the spring 37 and owing to the ball thrust bearing (1325) which allows housing 15 to pivot in all directions relative to the tube 44. When, after casting, the support device travels rearwardly under the effect of the extension of the spring 37 the counterfiange 32 of the housing 15* resumes contact with the flat face 40' of the recess 34 of the journal 6 As the counterfiange is still rotating and the journal 6 is fixed, the flat face 40 performs the function of a disc brake which rapidly stops the rotation of the rotating part II. Owing to this braking action, it is possible to place a new core N in position rapidly on the ring 20 with no loss of time (position shown in dot-dash line in FIG. 5).

Thus the rotating joint consisting of the ball thrust bearing (1325) allows the core N to rotate with respect to the non-rotatable support I consisting of the journal 6 and the tube 44.

The plug 43 and the. tail portion 46 of the tube 44 transmit to the core N a locking thrust exerted by a jack and thus lock the core, N in opposition to the pressure of the iron without preventing rotation of the core with respect to the tube 4 and the journal 6 which do not rotate. V

The spring 37 which performs the same function as the elastically yieldable end wall 37 of the element 17 of the first embodiment, applies the counterflange 32 elastically against the face 40 of the recess 34 of the journal 6 (braking eifect).

The free mounting of the outer rotating housing (which carries the core support ring with respect to the non-rotating journal 6 allows this housing to move. This free mounting is achieved by the radial clearance between the centre opening 33 of the counterflange 32" and the recess 34 of the journal 6 and by the axial clearance between the counterflange 32 and the plane face 40 of the recess 34, when the spring 37 is axially compressed by the jack for locking purposes.

(III) Modification of the invention shown in FIG. 6. This modification is derived directly from the device shown in FIG. 5. There is again provided an outer sleeve or housing 15 carrying the core N through radial arms 19 (rotatable part 11 Mounted on the end of a pivotable arm B (or at the end of a jack) is a non-rotating support rod 6* (non rotatable part 1*). This rod has an axis X-X and a flange 27 having, on the side thereof adjacent the arm B, a frustoconical rear face 29". Adjacent the core, the rod 6* acts as a support element for a spring 37 one end of which bears against the flange 27 The other end of the spring bears against the end wall 48 of a sleeve 44* disposed inside the housing 15 This sleeve 44 has an inside diameter much larger than the diameter of the rod 6 and substantially larger than the outside diameter of the coil spring 37 Mounted between the end of the housing 15 and the sleeve 44 is a rolling bearing, for example having barrel-shaped conical rollers 49 between an outer ring 50 disposed in the end of the housing 15 and an inner ring 51 which is mounted on the outer face of the sleeve 44* and bears against a shoulder 52 on the latter.

This support device operates in the same manner as that shown in FIG. 5. The core-locking thrust is transmitted from the rod 6 to the housing 15 through the flange 27 (which bears against the end face of the sleeve 44*) and the rolling bearing (49-51).

The core and the housing 15 can rotate in a noncircular manner with respect to the rod 6 owing to the barrel-shaped rollers of the bearing and to a large clearance between the sleeve 44" and the-rod 6*.

When the core is outside the mould, the housing 15 is elastically applied by the spring 37 against the flange 27 When the cast pipe is stripped from the mould, this flange constitutes a disc'brake for the still rotating housing 15 and stops it rapidly.

When the core is outside the mould, the support 15 is therefore centered on the frustoconical face 29' of the flange 27*.

Although specific embodiments of the invention have been described, many modifications and changes maybe made therein without departing from the scope of the invention as defined in the appended claims.

Thus the rolling thrust bearing (49, 50, 51) can have any other suitable constructional form, such as for example a spherical abutment or ball bearings.

Only a single radial arm 19 for supporting the ring 20 could be provided. A film of lubricant could be interposed. instead of a film of compressed air between the journal 6 and the sleeve 16 in the first embodiment.

Having now described my. invention what I claim as new anddesire to secure by Letters Patentis: v

1. A support and locking device for inserting and lock ing a corein a centrifugal casting mould, said device comprising a rotatable core carrier part, a non-rotatable part connected to handlingmeans, and a flexible assembly between said parts, said core carrier part comprising. a housing rotatably mounted on said non-rotatable part and extended by at least one arm, a ring carried on said arm at'a given axial distance from said housing, said ring being adapted for fixing the,v core thereon, andsaid carrier part being combined with an axial rolling thrust bearing which is interposed, on the axis of rotation ofthe core carrier part, between the core carrier part and said non- 1'.otatable part and with an elastically yieldable axial compression means which act inopposition to theaction of the thrust bearing for maintaining the elements in mutual contact. i 2. A device as claimed in claim 1, wherein the axial rolling thrust bearing consists of a single ball co-operating witha plate, said thrust bearing being interposed between said non-rotatable part and the rotatable core carrier part.

3. A device as claimed in claim 1, wherein the core carrier part is rotatably mounted on a fixed journal constituting said non rotatable part and is'coaxial with the rolling thrust bearing, said core carrier part comprising two rigid elements between which an elastomersleeve element is interposed, said elastomersleeve element constituting in one portion thereof said'yieldable axial compression means.

4. A device as claimed in claim 2, wherein said rotatable core carrier part comprises a rigid outer core-carrying housing and an inner rigid sleeve, said elastomer element being interposed between Said housing and said sleeve.

5. A device as claimed in claim 4, wherein the elastomer element encompasses said rigid sleeve, inner and outer ribs respectively on the outer housing and said inner sleeve being embedded inthe interposed elastomer element and ensuring that the elastomer element and housing rotate together.

6. A device as claimed in claim 3, wherein the journal comprises passages for blowing compressed air communicating with the outer cylindrical face of the journal in front of a borein said rigid sleeve which is retained axially by a flange of said journal.

7. A device as claimed in claim 6, wherein said rigid sleeve has a flange having a frustoconical retaining rublbing and centering face with which co-operates a counterflange which is integral with the housing and has an opening with a chamfered portion corresponding to said frustoconical face of said flange, a large radial clearance being provided between said opening and said rigid inner sleeve.

8. A device as claimed in claimZ, wherein the axial rolling thrust bearing is interposed between a rigid sleeve constituting said rotatable core carrier part and said nonrotatable part and said elastically yieldable axial compression means is a coil spring coaxial with said rolling thrust bearing. t

9. A device'asclaimed in claim 8, wherein said 'nonrotatablepart comprises a non-rotatable 'sle'eve constituting a journal for said 'core carrierpart and connected to handling means, and a tube which is mounted in'said sleeve and carries at one end the abutment ball and transmits the axial fcore-lockin'g thrust to said ball through the other end of the tube against which the end of said journal abuts, whereas the coil spring is compressed between a shoulder on the tube and the end wall of the journal. I v p p 10. A device as claimed in claim 9, wherein the journal has a head portion adjoining a large recess. and mounted with a large radial clearance inside a housing constituting ai -rotatable core support, said head having a plane outer transverse support andrubbing face adjoining a frustoconical centering face for centering said housing which has a flange adapted to bear against said plane and frustoconical faces, said flange having a center opening whose diameter equals the largest diameter of the frustoconical face and greatly exceeds that of the end of said recess in the journal so as to provide a large radial clearance therebetween.

11. A device as claimed in claim 9, wherein a nonrotatable journal is interposed with a large radial clearance between the rotatable housing and a non-rotatable support rod connected to the handling means, a rolling thrust bearing having rollers mounted inside the housing being interposed between the housing and the non-rotatable journal.

12. A device as claimed in claim 11, wherein the nonrotatable support rod forming a journal has an axially retaining and friction flange adjoining a frustoconical centering face with which the plane transverse face on the flange of the housing co-operates, the center opening of said flange forming a large clearance with the nonrotatable rod.

References Cited UNITED STATES PATENTS 3,004,314 10/1961 Beyer 164293 X 3,168,765 2/1965 Bernhardt 164302 3,412,785 11/1968 Lorang 164298 X JOHN S. BROWN, Primary Examiner US. Cl. X.R. 164302; 249-137

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