US3738065A

US3738065A - Machine for trimming and bevelling the edges of ophthalmic lenses

Info

Publication number: US3738065A
Application number: US00111503A
Authority: US
Inventors: L Tagnon
Original assignee: LUNETIERS
Current assignee: LUNETIERS; SOC DES LUNETIERS FR
Priority date: 1970-02-03
Filing date: 1971-02-01
Publication date: 1973-06-12
Anticipated expiration: 1990-06-12
Also published as: JPS5119199B1; DE2104157B2; DE2104157A1; FR2079496A5

Abstract

A device designed for fastening the end of a rotatably driven spindle to an object of substantially flat configuration. The device comprises a first plate rotatably driven from a rotary spindle and a second plate adapted to clamp the object against the first plate and is rotatably mounted through the medium of an axial thrust rolling-contact bearing to the end of another axially movable spindle carried by the end of a bracket, together with means to cause the axial movement of the other spindle. A resilient sleeve is interposed between the bracket and the second spindle to enable the second spindle to perform transverse movements in relation to the axis of the first spindle while resiliently and axially urging the second spindle towards the object. The device is applicable to the clamping of a templet in a machine for trimming and/or bevelling or edge-grinding ophthalmic lenses.

Description

wiililenl States atent 1 Tagnon [75] Inventor: Luc A. Tagnon, Saint Mande, France [73] Assignee: Societe des Lunetiers, Paris, France [22] Filed; Feb. 1, 1971 [21] Appl. No.: 111,503

[30] Foreign Application Priority Data Feb. 3, 1970 France 7003722 [52] 11.8. C1. 51/101 LG, 51/217 L [51] int. Cl v. B2411) 7/00, B241) 9/00, B24b 41/06 [58] Field of Search 51/101, 101 LG, 217 L [56] References Cited UNITED STATES PATENTS 691,225 1 1902 Wilson ..L 51 1'01 LG 1,184,496 5/1916 Stcnvall..... 2,166,037 7/1939 Camp0s..... 3,121,979 2/1964 Gray et al.. 3,332,172 7/1967 Stern 51/101 LG June 12, 1973 [57] ABSTRACT A device designed for fastening the end of a rotatably driven spindle to an object of substantially flat configuration. The device comprises a first plate rotatably driven from a rotary spindle and a second plate-adapted to clamp the object against the first plate and is rotatably mounted through the medium of an axial thrust rolling-contact bearing to the end of another axially movable spindle carried by the end of a bracket, together with means to cause the axial movement of the other spindle. A resilient sleeve is interposed between the bracket and the second spindle to enable the second spindle to perform transverse movement in relation to the axis of the first spindle while resiliently and axially urging the second spindle towards the object. The device is applicable to the clamping of a templet in a machine for trimming and/or bevelling or edgegrinding ophthalmic lenses.

11 Claims, 14 Drawing Figures PATENTED JUN I SHEEIIUFS ig- PRIOR ART Fig.5.

PRIOR ART PAIENIEDJum 2 ms SHEEI 2 0f 5 '0 O i In.

PAIENIEU JUN 1 2197s sum 3M5 FIELD OF THE INVENTION The present invention relates to machines for trimming and/or bevelling or edge-grinding ophthalmic lenses, notably a trimming and/or bevelling machine operating by reproduction, and more particularly to a device permitting of fastening an object of relatively flat configuration, notably an ophthalmic lens, to the end of a rotatably driven spindle, and intended more particularly for use in a machine of this character.

DESCRIPTION OF THE PRIOR ART In hitherto known machines for trimming and/or bevelling or edge-grinding optical lenses, notably machines operating according to the so-called reproduction method the glass workpiece or lens blank to be trimmed or of which the edge is to be glazed or bevelled by means of a grinding wheel, is clamped in a predetermined position between a pair of plates positively driven for continuous rotation from a pair of coaxial spindles. The templet or model lens utilized as a pattern is clamped, also in a well-defined position, between two plates of which one is rotatably driven from one of the spindles driving'the workpiece. The other clamping plate of the templet or model lens is rotatably mounted by means of an axial thrust bearing of the rolling contact type to the end of another spindle adapted to be moved axially by means of suitable control members for clamping its templet or the model lens against the first clamping plate associated therewith. The lastnamed spindle is supported by one end of a bracket supported in turn by the frame structure of the machine in which the spindle driving the first plate is rotatably mounted.

Before commencing the grinding or bevelling operations a glass workpiece and a templet (or the glass model or model lens) are placed on one of their relevant clamping plates with the assistance of centering members know per se, in well-defined relative positions with respect to identical reference marks carried by the machine, whereby the contour of the templet, which is to be reproduced on the workpiece, occupies a welldefined position with respect to the optical properties of the glass workpiece to. be mounted in a predetermined spectacle frame. If the templet comprises, in a manner known per se, a plurality of holes engageable without play by pins carried by the first (driving) plate, the necessary clamping effect exerted by the other plate associated with the templet is relatively low because its only purpose is to keep the pins engaged in the templet holes. Moreover, under these conditions, the pins provide a rigid mechanical connection between the first plate and the templet, whereby, this templet is positively held in the proper position between the two plates associated therewith. On the other hand, if the templet does not comprise any hole or if the contour to be reproduced is the contour of a model lens of any configuration acting as a templet, the hole-free templet or model lens must be held only by clamping between the two plates, without any rigid mechanical coupling (i.e. without using any driving pins). Therefore, inthe following disclosure the term templet is used to designate either a'flat templet without positioning holes, or a model lens of any desired shape of which it is desired to reproduce the contour on another lens. Now it is extremely important that the position given initially to the templet by means of the centering members be strictly maintained not only during the clamping of the templet between its two plates but also when this templet is being rotatably driven, only by friction, from one of its clamping plates and/or when it co-acts with a control feeler associated therewith.

However, in machines of the above-described type, wherein the spindle of the second clamping plate or clamping spindle is supported by the end of a bracket, it appears that during the clamping of this second plate against the templet a reaction develops which is transmitted to the end of said bracket and causes the bracket to be somewhat deflected. As a result, the axis of the clamping spindle is no longer coincident with the axis of the rotatably driven spindle, as clearly shown by the diagram of FIG. 1 of the attached drawings. In fact, this FIG. ll shows a first spindle 1 rotatably driven and carrying a plate 2 mounted to, and rotatably rigid with, this spindle, and also another spindle 3 (i.e. the clamping spindle) carried by the end 4 of the bracket (of which only this end 4 is illustrated) to which a second clamping plate 5 is rotatably mounted. To clamp between these

plates

2 and 5 an object of relatively flat configuration, for example a model lens V, the spindle 3 may be moved axially in the direction of the arrow 6 by means of clamping members (not shown) co-acting on the one hand with this spindle and on the other hand with the end 4 of the bracket, so as to provide a rigid mechanical. coupling between these two elements. When no clamping force is applied to the spindle 3, the axis thereof is coincident with the axis of spindle 1. On the other hand, as already pointed out in the foregoing, when a clamping force is exerted on the spindle 3 the reaction thus produced and transmitted through the rigid mechanical coupling to the bracket causes the latter to undergo a certain deflection, whereby the axis of spindle 3 is no longer coincident with that of the spindle 1. Under these conditions, the two

plates

2 and 5 are no longer parallel and any adequate clamping of the model lens V between these two plates is precluded, as shown in FIG. 1.

In order to restore the parallel relationship between these two

plates

2 and 5, it is known to provide a ballor swivel-joint 7 between any one of these two plates and the spindle 1 or 3 associated therewith, for example between plate 5 and spindle 3, as shown in FIG. 2 of the attached drawings. If, by virtue of this ball-joint 7 a uniform clamping action of the model lens V between

plates

2 and 5 is obtained when the assembly remains static, no solution is brought about inasmuch to the problem of strictly maintaining the model lens V in the position initially selected therefor in relation to the plate 2 when this plate 2 rotatably drives by friction the model lens V. In fact, since the axes of spindles 3 and 1 respectively are constantly off-set and, generally, the axis of spindle the I does not pass through the center of the ballor swivel-joint 7, points of major resistance or so-called hard points develop when the plate 2 is caused to rotate the model lens V by friction and this lens V drives in turn the plate 5. The points of major resistance or hard points cause the plate 5 and lens V to skid on each other. Now these transverse forces not only involve a change in the adjustment of the initial centering of the lens V with respect to the plate 2 by causing the lens V to skid likewise in relation to this plate 2, but may cause the lens to be ejected from between the two clamping plates. In order to simplify the proof of thislack of stability of the lens V between the two plates, it was assumed, in the above description given with reference to FIGS. 1 and 2, that the model lens V had two plane and parallel faces, but it is obvious that the lens instability is further increased and that the holding of this lens in the position initially contemplated therefor is still more difficult to achieve when, as observed in actual practice, this lens has curved, non-parallel major faces. With the known clamping devices broadly described in the foregoing it is therefore not possible to preserve the initial centering of model lens V between the

clamping plates

2 and 5, and this obviously constitutes a major drawback when a clamping device of this character is used for holding a templet or a model lens in a trimming and/or bevelling or edge-grinding machine operating according to the reproduction process.

SUMMARY OF THE INVENTION The present invention aims primarily at avoiding this inconvenience by providing a device capable of fastening to the end of a rotatably driven spindle an object of substantially fiat configuration, such as an ophthalmic lens, this device comprising a first plate carried by the end of said rotary spindle and adapted to co-act with one of the two main faces of the flat object in order to drive same by friction. A second plate is pressed against the other main face of said object for clamping same against the first plate and rotatably mounted by means of an axial bearing 'of the rolling-contact type to one end of a second axially movable spindle having its axis coincident with the axis of rotation of the first spindle when no clamping force is applied to said second spindle. The second spindle is supported by one end of a bracket supported in turn by a frame structure in which the first spindle is rotatably mounted, as well as means for axially moving the second spindle in order to clamp the object between the two plates or release the object therefrom. This device is characterized in that first and second resilient members are interposed between the second spindle and the adjacent end of the bracket. A first resilient member permits transverse movements of the second spindle in relation to the axis of rotation of said first spindle during the rotation of said flat object. The second resilient member is adapted to resiliently and axially urge the second spindle towards the object.

BRIEF DESCRIPTION OF THE DRAWINGS.

This invention will be better understood as the following detailed description proceeds with reference to the accompanying drawings illustrating diagrammatically by way of example various forms of embodiment given by way of example; in the drawings:

FIGS. 1 and 2 illustrate diagrammatically the principle of operation of two plate-type clamping devices of the prior art;

FIG. 3 is a diagram illustrating diagrammatically the principle of operation of a clamping device according to this invention;

FIGS. 4 and 5 are a front elevational view and a side elevational view of the essential component elements of a machine for trimming and/or bevelling or edgegrinding ophthalmic lenses by reproduction, in which the present invention can be embodied;

FIG. 6 is a fragmentary perspective view on a larger scale and in partly in section of a typical form of embodiment of the clamping device of this invention as applied to a machine of the type illustrated in FIGS. 4 and 5;

FIGS. 7 and 8 are perspective views showing in two different cases the behavior of the clamping device of this invention during its operation;

FIG. 9 is a fragmentary axial section showing one portion of the clamping device of FIG. 6;

FIGS. 10 to 12 are axial sections illustrating modified forms of the portion shown in FIG. 9;

FIGS. 13 and 14 are fragmentary views partly in section showing other modified forms of embodiments of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As already explained hereinabove with reference to FIGS. 1 and 2, when a plate 2 rotatably driven from a spindle 1 drives by friction the lens V driving in turn by friction the other plate 5, points of major resistance or hard points appear during the rotation of the assembly. These hard points are due mainly to the fact that the axes of spindles 1 and 3 are mutually off-set and that the spindle 3 is rigidly supported at 4. The present invention is based on this last fact. Actually, if as shown in FIG. 3 the spindle 3 can move both axially and transversely, the holding or clamping plate 5 can be friction driven through the lens V without developing any hard points during the rotation. Thus, each point of plate 5 describes during this rotation substantially a circle centered on the axis of the spindle 1. In FIG. 3 the

reference symbols

3a, 5a and 7a denote the positions assumed by a spindle 3, plate 5 and ball-joint 7, respectively, after the

clamping plates

2 and 5, and lens V, have accomplished a half-revolution about the axis of a spindle 1.

FIGS. 4 and 5 illustrate by way of example, not of limitation, a type of machine in which the present invention may be carried out. This machine 10 (of which only the essential component elements are illustrated) is designed for trimming and/or bevelling or edgegrinding optical lenses by reproduction. It comprises essentially a grinding wheel 11 rotatably driven through known means (not shown) and a contact feeler 12. The wheel 11 and the feeler 12 are carried by the main frame structure (not shown) of the machine and are adapted to engage a workpiece glass lens 13 and a templet or model lens 14, respectively, so as to reproduce the contour of this templet or model lens 14 on the workpiece lens 13. The workpiece lens 13 is clamped between two

plates

15 and 16 carried by

spindles

17 and 18, respectively, rotatably driven through adequate means (not shown). These

spindles

17 and 18 are axially aligned and rotatably mounted in the ends of a strap-shaped auxiliary frame 19 of the machine. The spindle 17 and its plate 15 are adapted to be moved in the axial direction by means of a control system 20 for clamping the lens 13 between the

plates

15 and 16, or releasing the lens therefrom. Spindle 18 has an extension projecting from the auxiliary frame 19 and carries a plate 21 co-acting with one of the major faces of the templet or model lens 14. Another plate 22 engages the opposite major face of a templet or model lens 14 and is adapted to be urged against this face by another spindle 23 axially movable in either direction by means of a control device 24. This spindle 23 is supported by one end of a bracket 25 supported in turn by the auxiliary frame 19. The control device 24 consists for example of a screw rigid with the spindle 23 and engaging a tapped hole formed in the free end 4 of the bracket 25. Plate 22 is rotatably mounted on the end of the spindle 23 with the assistance of an axial thrust bearing 26 of the rolling contact type. Theoretically, the

spindles

18 and 23 are coaxial and the plate 21 rotatably driven by the spindle 18 drives in turn, by friction, the plate 22. The auxiliary frame or similar structure 19 is pivotally mounted on a shaft 27 (FIG. 5) carried by the main frame structure of the machine. The axis of this shaft 27 is parallel to the common axis of the

spindles

17, 18 and 23. Moreover, resilient return means 28 constantly urge the frame 19 for pivoting about the axis of the shaft 27 in the direction of the arrow 29 (FIG, 5) so as to press the workpiece lens 13 against the grinding wheel 11. I

Before starting the machine the workpiece lens 13 and templet 14 are placed in well-defined respective positions between their corresponding clamping plates in order to reproduce on the lens 13 the contour of the templet 14, whereby the optical characteristics of the lens lie in a well-defined position in relation to this contour. It is therefore essential that the workpiece lens 13 and the templet 14 be properly clamped between their corresponding pairs of clamping plates so that throughout the grinding operations they remain in the positions in which they were set initially, in spite of the lateral efforts to which they are subjected, the one through grinding wheel 11 and the other through contact feeler 12. In machines of the above-described type (see FIGS. 4 and 5), which are well known per se, the lens 13 is clamped and held in its initial or pre-set position without giving rise to any particular problem, but the same does not apply to the clamping and holding of the templet 14 between

plates

21 and 22 associated therewith. In fact, as already mentioned in the foregoing, when the plate 22 is clamped against thetemplet 14 by the control device 24 and spindle 23, the bracket 25 is subjected to a reaction force tending to bend it. This bending moment is illustrated by the angle a in FIG. 6. As a result, the axis YY of spindle 23 is no longer coincident with the axis XX of spindle 18, and the plate 22 does not bear uniformly on the templet 14. However, this inconvenience may be avoided in a manner known per se, i.e., by mounting the

plate

21 or 22 on the

spindle

18 or 23 associated therewith, through the intermediary of a ball-joint or a universal or Hookes joint.

However, since the axes XX and YY are still off-set, hard points develop during the rotation of plate 21, templet 14 and plate 22, and these hard points not only impair this rotation but upset the initial, accurate centering of the templet 14; under certain circumstances, these hard" points may even lead to a rupture of the templet 14 if the latter consists of a model lens of relatively moderate thickness.

According to this invention this inconvenience is eliminated by providing means for resiliently supporting the spindle 23 on the free end 4 of the bracket 25 so that it can perform transverse movements in relation to the axis XX of the spindle l8 and be pushed resiliently towards the templet 14. Thus, the rotation can take place without any hard points and the plate 22 remains constantly pressed with a uniform force against the templet 14.

PEG. 6 illustrates a practical form of embodiment of this invention. As clearly shown in this FIG., the end 4 of the bracket 25 has a bore 30 formed therein, of which the axis is normally merged into the-axis XX of spindle 18 under normal conditions, i.e., when no axial clamping effort is exerted on the spindle 23. This spindle 23 is resiliently supported in the bore 30 by means of a resilient coaxial sleeve 31. In order to permit the axial movements of the spindle 23 the latter carries a control knob 32 at its outer end and comprises a screwthreaded portion 23a engaging an internally screwthreaded socket 33 interposed between the resilient sleeve 31 and the spindle 23. The tapped socket 33 carries at its end facing the plate 22 a flange 33a and the resilient sleeve 31 bears axially with one end against this flange 33a and with its opposite end against a shoulder 30a formed inside the bore 30. Thus, the resilient sleeve 31 is held against axial translation in either direction by the shoulder 30a and flange 33a.

When the spindle 23 is screwed in the tapped socket 33 by turning the control knob 32 in order to press the plate 22 against the templet 14, immediately as the plate 22 contacts the templet 14 (so that the templet 14 counteracts the axial movement of the spindle 23, the flange 33a of the tapped socket 33 begins to compress the resilient sleeve 31 against the shoulder 30a and conversely, by reaction, the thus compressed resilient sleeve 31 resiliently urges the tapped socket 33, spindle 23 and plate 22 towards the templet 14, i.e., in the axial direction.

The plate 22 bears against one of the major faces of templet 14 through a resilient O-ring 34 and plate 21 bears against the other major face of the templet 14 through a resilient sleeve 35 projecting from this plate 21. Due to the clamping action exerted by the spindle 23 this resilient sleeve 35 is distorted as shown at 35a so that the plate 22 can bear' uniformly through its 0- ring 34 against the templet 14. Under these conditions the resilient sleeve 35 has the same function as the balljoint 7 of FIGS. 1 to 3. Moreover, the wall thickness of this resilient sleeve must be sufficient to ensure firstly perfect distribution of the clamping distortion by maintaining the centering of templet 14 with respect to axis XX, secondly a perfect distribution of the contact pressure necessary for rotatably driving the templet 14 without producing any hard points, and thirdly a good resistance to the clamping pressure of the templet 14 between

plates

21 and 22. Although in the exemplary form of embodiment shown in FIG. 6 the resilient sleeve 35 is carried by the plate 21 and the O-ring 34 is carried by the plate 22, the reverse arrangement could be adopted as well by causing the resilient sleeve 35 to be carried by the plate 22 and O-ring 34 by the plate 21.

As already pointed out in the foregoing, as a consequence of the clamping action the bracket 25 tends to yield as shown by the angle a of FIG. 6; as a result, the axis WW of the bore 30 deviates from the axis XX of the spindle 18. Moreover, due to the different shapes of the two major surfaces of the templet 14, the axis YY of the spindle 23 assumes a position still different from the positions of axis WW of the bore 30, and XX of the spindle 18. The different positions assumed by axes XX, YY and WW respectively are better evidenced in FIGS. 7 and 8 the former corresponding to the specific case wherein the major faces of templet 14 have a common plane of symmetry, and the latter to a case wherein these two major faces have no common plane of symmetry. In these FIGS. 7 and 8 the plate 21 and its resilient sleeve 35 acting as a ballor swiveljoint as described hereinabove with reference to FIG. 6, are illustrated in the form of a plate 21 connected through a ball-joint forming a flexible connection 210 to the spindle 18. As a matter of fact, this arrangement could be employed in actual practice and to this end a clamping jaw of the type described with reference to FIG. of the French Pat. No. 1,577,425 could be used to advantage.

In FIG. 7, the major faces 14a and 14b of the templet or model lens 14 have a common plane of symmetry and it will be assumed that this plane of symmetry is the meridian plane M of the templet 14. Under these conditions the axis XX of the spindle 18, axis WW of bore 30 and axis YY of the spindle 23 assume as a consequence of the clamping action and for the reasons set forth in the foregoing the various positions shown in FIG. 7, with these three axes in the aforesaid common plane of symmetry, and the axis YY intersecting the axis XX at a point I. When the clamping plate 21 is rotatably driven by spindle 18 the former causes the rotation, by frictional engagement, of the templet 14 driving in turn, also by frictional contact, the other plate 22. The rotation of the assembly comprising the two clamping

plates

21, 22 and the templet 14 is made possible by the fact that spindle 23 is resiliently supported by the end 4 of the bracket 25. Under these conditions, when the aforesaid assembly is rotatably driven the axis YY of the spindle 23 generates a cone of revolution about the axis XX and the apex or point of intersection I. As clearly shown in FIG. 7, if as in the case of hitherto known devices the spindle 23 were rigidly supported by the end 4 of the bracket 25, i.e., with its axis YY fixed and merging into the axis WW of the bore 30, the plate 22 having an eccentric position in relation to axis XX could not be properly driven by the templet 14 and therefore hard points would develop during the rotation, thus causing the templet 14 to skid in or move relation to the pair of clamping

plates

21 and 22.

In FIG. 8, the major faces 14a and 14b of templet 14 have no common plane of symmetry. As a result, when the templet is clamped by the plates, the axes XX, YY and WW of the spindle 18, spindle 23 and bore 30 respectively are immaterial with respect to one another. Under these conditions, when the plate 21 rotatably drives templet 14 by frictional contact, the templet 14 causing similarly the rotation of plate 22, the axis YY of spindle 23 generates substantially a hyperboloid with one sheet of revolution about the axis XX. The rotational movement of the assembly comprising the plate 21, the templet 14 and plate 22 is still possible, without any hard points, since the spindle 23 is resiliently supported by the end 4 of bracket the 25. In FIGS. 6, 7 and 8 the degree of off-set of the axes XX, YY and WW respectively have been exaggerated in order to more clearly show the general arrangement. In actual practice these divergences are considerably smaller but, although moderate their importance is considerable as far as the quality ofthe clamping action and the holding of the templet 14 between the clamping

plates

21 and 22 are concerned.

FIG. 9 is a fragmentary sectional view showing the manner in which the spindle 23 is resiliently supported by the bracket 25. This modified form of an embodiment is substantially the same as that illustrated in FIGv 6 except that the bore 30 of the bracket 25 comprises in the vicinity of the flange 33a of the tapped socket 33 a portion 30b of greater diameter enabling the resilient sleeve 31 to expand radially when it is compressed in the axial direction by the flange 330. This arrangement enables the resilient sleeve 31, after an axial compression, to preserve its entire flexibility during the transverse movements of the spindle 23 and the socket 33.

FIGS. 10 and 11 are views similar to FIG. 9 but showing modified forms or embodiments. In FIGS. 10 and 11 the resilient sleeve 31 is mounted coaxially in the bore 36a of a hollow screw 36 and surrounds the rear end of spindle 23 which it engages directly. Moreover, the resilient sleeve 31 bears in the axial direction with one end against the bottom 36b of the bore 36a and with the opposite end against a flange 23b rigid with the spindle 23. The aforesaid hollow screw 36 engages the end portion of the bracket 25 and carries a knurled control head or knob 32. To press the plate 22 against the templet 14 (not shown in FIGS. 10 and 11 it is only necessary to rotate the screw 36 in the proper direction within the bracket end by means of the control knob 32 and when the clamping plate 22 engages the templet 14 the clamping force is transmitted elastically and axially to the spindle 23 through the resilient sleeve 31 compressed between the bottom 36b and flange 23b. In addition, as in the form of the embodiment of FIG. 9, the spindle 23 is adapted, owing to the inherent flexibility of resilient sleeve 31, to perform the transverse movements necessary for the proper operation of the assembly. The form of embodiment illustrated in FIG. 11 differs from that of FIG. 10 in that the flange 23b of the spindle 23 acts as an abutment both to the resilient sleeve 31 and to the rolling contact thrust bearing 26.

In all the forms of embodiments described hereinabove the resilient sleeve 31 is so arranged that it permits both transverse movements of the spindle 23 and the elastic and axial transmission of the clamping force to spindle 23 during the clamping movement of plate 22 against the templet 14. However, if desired, these two functions performed by the resilient sleeve 31 may be disassociated and performed by two different members, as illustrated by way of example in FIG. 12.

In FIG. 12 the rod 23 is slidably mounted in a guide sleeve 37. The resilient sleeve 31 is interposed between this guide sleeve 37 and the wall of the bore 30 formed in the end portion of the bracket 25. In this case the resilient sleeve 31 is used only for transmitting the transverse movements of the spindle 23. On the other hand, the axial movements of this spindle 23 are obtained by means of the control knob 32 rigid with a screw 38 engaging a tapped hole formed coaxially with the spindle 23 in a strap 39 rigid with the bracket 25 and bearing resiliently against the rear end of the spindle 23 so as to resiliently transmit to this spindle the axial movements and the clamping force produced by properly rotating the control knob 32. In the example illustrated the screw 38 is hollow and encloses a coil compression spring 40 resiliently urging in an axial direction, a piston 41 and its piston rod 42 towards the rear end of the spindle 23. Since during operation this spindle 23 performs transverse movements, the end of the piston rod 42 carries a ball 43 permitting a rolling contact between this rod 42 and the rear end of the spindle 23.

As already mentioned hereinabove, it is adequate to interpose a Hooke's universal joint or a ball-or swivel joint between one of the plates and the spindle associated therewith, in order to enable both

plates

21 and 22 to exert a uniform pressure against the templet 14 and thus properly clamp the latter between the plates. In FIG. 6 the resilient sleeve 35 acts as a ball joint and in FIGS. 7 and 8 the plate 21 is carried by a flexible rod 21a also acting as a ball joint. However, it will readily appear to those conversant with the art that a real ball joint or universal joint could be used as well to this end. FIG. 13 illustrates a modified form of embodiment wherein the plate 21 is connected through a Hookes universal joint 44 providing two degrees of liberty or two types of angular movements in order to permit the driving of the plate 21 from the spindle 18. FIG. 14 shows another form of embodiment in which the plate 22 is carried by a ball-joint 45.

Of course, the various embodiments described hereinabove should not be construed as limiting the inven tion, since they are given by way of illustration only; therefore, many modifications may be brought thereto without departing from the basic principle of the invention as set forth in the appended claims.

Thus, more particularly in the foregoing the device according to this invention for clamping and rotatably driving a member is used in a machine for trimming and/or bevelling or grinding the edges of ophthalmic lenses by reproduction, but it can also be incorporated in a small, simple trimming and/or bevelling machine in which the lens workpiece or blank clamped between two plates is driven from only one of these two plates.

I claimf 1. An edging machine for edging and beveling a lens blank by reproduction, comprising a frame, a driven spindle rotatably mounted in said frame, a first clamping plate mounted on said driven spindle at one end thereof for engaging one major surface of a templet having two opposite major surfaces, an L-shaped bracket having one arm connected to the frame and extending in a parallel direction to said driven spindle, the other arm of said bracket having a free end and lying in a plane defined by the first arm and the driven spindle, another spindle supported at one end thereof by said free end of said bracket in a substantially aligned relationship with respect to said driven spindle, a second clamping plate mounted on the other end of said other spindle for engaging the other opposite major surface of said templet, means for resiliently urging said other spindle and the second clamping plate associated therewith towards said first clamping plate to clamp said templet between said first and second clamping plates, first resilient means provided between said free end of said bracket and said one end of said other spindle for resiliently supporting said other spindle in a transverse direction thereof, thereby permitting rotation of said other spindle, when driven by said driven spindle through the clamped templet, without any point of resistance during rotation even in the presence of a slight misalignment of said other spindle with respect to said driven spindle which occurs when a clamping force is applied to said other spindle by said urging means.

2. An edging machine as set forth in claim 1, wherein said urging means comprise means for causing axial movement of said other spindle selectively towards and away from the first clamping plate and for applying a clamping force to said other spindle in the axial direction thereof when moved towards said first clamping plate, and second resilient means between said axialmovement causing means and said other spindle for resilicntly transmitting to said other spindle the axial clamping force of the axial-movement causing means.

3. An edging machine as set forth in claim I, wherein one of said first and second clamping plate is mounted on the associated spindle through a universal joint.

4. An edging machine as set forth in claim 1, including a sleeve carried on one of said first and second clamping plate and made of resilient material operative to engage one of the two major surfaces of the templet and having means acting when engaged with said one major surface as a universal joint between said templet and the clamping plate carrying said sleeve.

5. An edging machine as set forth in claim 2, wherein said free end of said bracket has a bore formed therein which is substantially coaxial with said other spindle and has a diameter greater than that of said other spindle so that an annular space is left between said other spindle and the wall of said bore, and said first resilient means comprises a sleeve of resilient material located in said annular space.

6. An edging machine as set forth in claim 5, wherein said other spindle is screw-threaded, and the means for causing axial movement of said other spindle comprise a control knob rigid with said one end of the other spin dle and a tapped socket threadedly engaging said screw-threaded other spindle, the sleeve of resilient material being fitted on said socket.

7. An edging material as set forth in claim 6, wherein said bore in said free end of the bracket has an annular shoulder formed therein, said annular shoulder facing towards said second clamping plate, said tapped socket has a collar projecting radially outwardly of said tapped socket, and said sleeve of resilient material is held between said annular shoulder and said collar so as to be prevented from axial movement in both axial directions, said sleeve thereby constituting also said second resilient means.

8. An edging machine as set forth in claim 2, wherein said free end of said bracket has a tapped bore formed therein, which is substantially coaxial to said other spindle, said means for causing axial movement of said other spindle comprise a screw threadedly engaging said tapped bore and having an axial bore formed therein, said axial bore in said screw having a diameter greater than that of said other spindle so that an annular space is formed between the wall of said axial bore and said other spindle, and said first resilient means comprises a sleeve of resilient material located in said annular space.

9. An edging machine as set forth in claim 8, wherein said axial bore in said screw has an abuting surface formed therein, said abuting surface facing towards said second clamping plate, said other spindle has a collar, and said sleeve of resilient material is held between said abuting surface and said collar so as to be prevented from axial movement in both axial directions, said sleeve thereby constituting also said second resilient means.

10. An edging machine as set forth in claim 5, including a guiding sleeve, said other spindle being slidably mounted in said guiding sleeve, said guiding sleeve being disposed between said sleeve of resilient material and said other spindle, and said means for causing axial movement of said other spindle comprise a screw axially engaging the end face of said one end of said other spindle and operative, when screwed, to make said other spindle slide in the guiding sleeve in the direction towards said templet.

11. An edging machine as set forth in claim 10, wherein said second resilient means is located between said screw and said end face of said one end of the other spindle.

Claims

1. An edging machine for edging and beveling a lens blank by reproduction, comprising a frame, a driven spindle rotatably mounted in said frame, a first clamping plate mounted on said driven spindle at one end thereof for engaging one major surface of a templet having two opposite major surfaces, an L-shaped bracket having one arm connected to the frame and extending in a parallel direction to said driven spindle, the other arm of said bracket having a free end and lying in a plane defined by the first arm and the driven spindle, another spindle supported At one end thereof by said free end of said bracket in a substantially aligned relationship with respect to said driven spindle, a second clamping plate mounted on the other end of said other spindle for engaging the other opposite major surface of said templet, means for resiliently urging said other spindle and the second clamping plate associated therewith towards said first clamping plate to clamp said templet between said first and second clamping plates, first resilient means provided between said free end of said bracket and said one end of said other spindle for resiliently supporting said other spindle in a transverse direction thereof, thereby permitting rotation of said other spindle, when driven by said driven spindle through the clamped templet, without any point of resistance during rotation even in the presence of a slight misalignment of said other spindle with respect to said driven spindle which occurs when a clamping force is applied to said other spindle by said urging means.

2. An edging machine as set forth in claim 1, wherein said urging means comprise means for causing axial movement of said other spindle selectively towards and away from the first clamping plate and for applying a clamping force to said other spindle in the axial direction thereof when moved towards said first clamping plate, and second resilient means between said axial-movement causing means and said other spindle for resiliently transmitting to said other spindle the axial clamping force of the axial-movement causing means.

3. An edging machine as set forth in claim 1, wherein one of said first and second clamping plate is mounted on the associated spindle through a universal joint.

6. An edging machine as set forth in claim 5, wherein said other spindle is screw-threaded, and the means for causing axial movement of said other spindle comprise a control knob rigid with said one end of the other spindle and a tapped socket threadedly engaging said screw-threaded other spindle, the sleeve of resilient material being fitted on said socket.