Device for deblocking lenses

Abstract

A device for deblocking lenses attached to a block has at least one securing device supporting a lens and having an opening for a block suspended from the lens. At least one holding-down device is provided for pressing the lens supported on the securing device against the securing device. At least one impacting device with a striking member movable from below against the securing device for striking the securing device is provided. The securing device and the holding-down device are supported to be movable against a spring-elastic restoring force in a striking direction of the striking member.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a device for deblocking optical glasses (lenses), in particular, spectacle lenses, which are fastened on a block, respectively. The device comprises at least one securing device on which a lens is supported and which has an opening for the block suspended from the lens. The device comprises at least one holding-down device for pressing the lens supported on the securing device against the securing device.

[0003] 2. Description of the Related Art

[0004] When manufacturing lenses of the aforementioned kind, the concave sides, inter alia, must be machined, for example, by milling, grinding, or polishing. The lenses to be processed are fastened by means of a low-melting alloy, whose melting point is approximately 55° C., on a so-called block. After completion of the individual processing steps, the lenses must be detached from the block. This separation of lens and block is commonly referred to as deblocking. This is carried out presently by hand. The lens fastened on the block projects laterally past the block. For deblocking by hand, a piece of tube is employed and the block is positioned in the tube opening. The diameter of the tube is of such a size that the lens, which radially projects relative to the block, will rest on the rim of the opening of the tube. The upright tube is then struck on a hard surface so that, as a result of the impact impulse, lens and block will separate. The block then falls through the tube downwardly, while the lens remains in the hand of the operator. This manual deblocking process is cumbersome and monotonous labor.

[0005] Austrian patent 407 967 already discloses a device for automatic deblocking. In this device, a carriage or slide, on which at least one holder for a lens with a block connected thereto is provided, is movable along a guide. The guide is part of a frame which is supported on a stand to be moveable in the vertical direction. For receiving the optical glasses (lenses) together with the blocks fastened thereto, the frame is lowered relative to the stand, the holders being open during this procedure. After closing the holders, the frame is again lifted and the carriage or slide is moved along the guide provided on the frame to the separating station. The frame is then lowered at great speed so that the jaws of the holder strike a plate of the separating station, and the acceleration force acting on the block now separates block and lens.

[0006] A disadvantage of this known device is that, for lowering the frame at great speed in order to realize deblocking, special piston-cylinder units for moving the frame must be employed which must have special venting valves in order to be able to reach the required high speed. This leads to increased manufacturing costs. Also, a change of the impact speed of the holder on the plate of the separating station is possible only with complex modifications. For this purpose, the piston-cylinder units have to be exchanged or the venting valves have to be modified such that a changed venting action can be achieved. The use of an electric motor drive for adjusting the frame (instead of the piston-cylinder unit) would require a relatively great manufacturing expenditure. Moreover, in this known configuration the mass to be moved for the deblocking process is relatively great so that high acceleration forces must be exerted causing great forces to be absorbed by the bearings.

[0007] A device for manual deblocking is also known from U.S. Pat. No. 3,091,062. The block is inserted into an upright standard so that minimal play relative to the standard remains. At the upper end of the receiving standard a ring is arranged which is pivotable relative to the standard by means of a lever and projects past the upper edge of the standard on which lens is supported. By pivoting the ring in the upward direction, the lens is removed from the block. The block, as a result of the exerted tilting force, is canted relative to the standard so that no additional securing device is required for the block. The one-sided force application onto the lens with this type of deblocking device results in a relatively great risk of breakage of the lens. Also, an automated operation of the device of U.S. Pat. No. 3,091,062 is not taught and, moreover, would not be possible with a device of the this kind.

SUMMARY OF THE INVENTION

[0008] It is an object of the present invention to provide an improved device of the aforementioned kind which can be produced less expensively.

[0009] In accordance with the present invention, this is achieved in that at least one striking device is provided which has a striking member movable from below against the securing device for striking the securing device, wherein the securing device and the holding-down device are movably supported against a spring-elastic restoring force in the direction of the impact or striking movement of the striking member.

[0010] In the device according to the invention, the masses which are to be moved upon deblocking can be reduced, and the device can be manufactured in a simpler way. Moreover, the deblocking process can be performed more reliably wherein the number of rejects in the form of lenses damaged by deblocking is reduced.

[0011] In an advantageous embodiment of the invention, the securing device in the area of the support of the lens is of a sleeve-shaped configuration wherein the block suspended from the lens is arranged within this sleeve-shaped area at a spacing to its inner wall. In this way, a simple securing device is provided wherein a deblocking device according to the invention can comprise several such securing devices with different diameters and/or the securing devices can be adjusted for receiving different sizes of lenses or blocks or they can be exchangeable.

[0012] It is expedient to provide the securing device with an anvil or support on a lower side opposite the lens resting on the securing device. The anvil should preferably be arranged centrally underneath the lens or the block suspended therefrom. This anvil or support serves for receiving the impact exerted by the striking member so that the impact acceleration detaching the lens from the block is transmitted via the anvil onto the securing device.

BRIEF DESCRIPTION OF THE DRAWING

[0013] In the drawing:

[0014] FIG. 1 is a side view of the device according to the invention;

[0015] FIG. 2 is a plan view of the device according to the invention;

[0016] FIG. 3 shows a section along the line A-A of FIG. 1 (the holding-down device and the striking device are not illustrated in section);

[0017] FIG. 4 shows a lens attached to a block in a side view (enlarged scale);

[0018] FIG. 5 shows the lens on the block in a top view (enlarged scale); and

[0019] FIG. 6 shows a bottom view of the lens on the block (enlarged scale).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] FIGS. 4 through 6 illustrate in different views the object to be manipulated by the deblocking device of the present intention. On a metal block 1, which in this illustrated embodiment has a conical portion 2 and a cylindrical portion 3 and is provided with a depression 4 arranged centrally and open in the downward direction, is fastened by means of a low-melting alloy 5 to the spectacle lens 6 to be processed whose concave side is to be machined. The block 1 can have different shapes and different sizes depending on the type of the optical glass (lens) to be treated. The aforementioned block 1 with the easily meltable alloy 5 is an auxiliary device with which the lens 6 to be processed is adjustable and positionable relative to the individual tools. The connection between the lens 6 and the easily meltable alloy 5 is of satisfactory or sufficient strength so that the reaction power caused by the tools when processing the lens can be transmitted safely and reliably onto the block 1 inserted into a machine tool. After completion of processing of the lens 6, the lens and the block must be separated. The device described in the following is provided for this purpose.

[0021] In the illustrated embodiment several securing devices 8 for blocked lenses 6 are provided on a carriage 7. Two rows of five securing devices 8 are provided. The carriage 7 is supported to be movable along guide rails 10 by means of glide shoes 9. The guide rails 10 are fastened on a machine frame 11. For moving the slide or carriage 7, a toothed belt 12 is provided on which the carriage 7 is secured by means of a holding part 13. The toothed belt 12 is of a continuous or closed configuration and runs on one side about a deflection roller 14 rotatably supported on the machine frame 11. The other side is provided with a drive roller (not visible in the illustration) driven by an actuator. In this way, the respective securing device 8 can be moved in an automated and program-controlled way into the required position in which deblocking of the lens 6 resting on the securing device is carried out.

[0022] Moreover, a loading station can be provided, which is not illustrated in the drawing, for supplying the securing devices 8 with the blocked lenses. In this connection, the carriage 7 can also be positioned by program control in order to load the respective securing device. In place of an electric actuator for the carriage 7, it is possible to provide a pneumatic adjusting devices instead.

[0023] For pressing an optical glass or lens 6 to be deblocked against the securing device, a holding-down device 15 is provided. In the illustrated embodiment, the holding-down device 15 is secured on a piston rod 16 of a pneumatic piston-cylinder unit 17 having a piston 18 acting via both ends. In the activate state of the holding-down device 15, air pressure loading the piston is present in the cylinder chamber 19. When a force is exerted onto the piston 18 which acts against this air pressure and is greater than the air pressure, the piston 18 is moved by reducing the cylinder chamber 19 against this air pressure so that the air pressure is increased. In this way, a kind of (pre-tensioned) air spring is formed against whose spring-elastic restoring force the holding-down device 15 can be moved when a correspondingly great force is exerted. In place of such an air spring device, or in addition thereto, a pressure spring could be provided, for example, between an adjusting device of the holding-down device 15 and the holding-down device 15; the holding-down device 15 can then be moved against the spring-elastic restoring force of this pressure spring.

[0024] The securing devices 8 are sleeve-shaped at their upper area facing the support of the lens 6. An inner sleeve part 20 is provided which is connected with an outer sleeve part 21. A plastic sleeve 22 is arranged between the inner and the outer sleeve parts 20, 21. O-rings 23, 24 are arranged on the upper end faces of the inner sleeve part 20 and of the plastic sleeve 22. The lens 6 is supported on the O-ring 23. The holding-down device 15 rests on the lens 6 and optionally on the outer O-ring 24. The block 1 suspended from the lens 6 projects through the opening 45 of the securing device 8 into the interior of the sleeve-shaped area of the securing device 8 and is spaced relative to the inner wall 25 of the inner sleeve part 20.

[0025] The sleeve-shaped upper area of the securing device 8 is closed off in the downward direction by a slantedly extending guide surface 26. This guide surface 26 opens into an ejection opening 27 for the deblocked block 1. The block 1 which has been deblocked from the lens 6 falls onto the guide surface 26 and then glides along it through the ejection opening 27 into a guide tube 28 which opens into a receptacle (not illustrated in the drawing) for the blocks 1.

[0026] The securing device 8 is axially slidably arranged in a glide sleeve 29 relative to the glide sleeve. The glide sleeve 29 is arranged in a support sleeve 31 which is connected to the frame of the slide or carriage 7. A coupling nut 32 is threaded onto the lower end of the support sleeve 31 and forces an elastic ring 33 against the lower end face of the support sleeve 31. The elastic ring 33 projects inwardly somewhat past the support sleeve 31, and the glide sleeve 29 rests on the elastic ring 33 in this area. The support sleeve 31 and the glide sleeve 29 are flush with one another at their upper ends, and on the upper end faces of these sleeves a damping ring 34 is positioned. In the lower end position of the securing device 8, a shoulder 30 of the securing device, where the diameter is reduced, rests on the damping ring 34. At the location where the shaft 35 of the securing device 8 projects downwardly from the coupling nut 32, an elastic rubber ring 36 is secured on the shaft 35 and surrounds it in a circular ring shape. This elastic rubber ring 36 provides a spring-elastic element against whose spring-elastically acting restoring force the securing device 8 can be moved upwardly in the axial direction by a small stroke. A bolt 37, secured in the support sleeve 31 and projecting into a corresponding recess in the area of the shoulder 30 of the securing device 8, provides a securing action against relative rotation.

[0027] On the lower end of the shaft 35 an anvil or support 38 is arranged and connected to the shaft 35. It is positioned centrally underneath the lens 6 or its block 1 suspended therefrom.

[0028] A device according to the invention comprises moreover a striking device 39 which comprises a striking member 40 in the form of a type of a hammer. The striking member 40 is secured on the piston rod 41 of a piston-cylinder unit 42 and, in its inactive rest (initial) position before carrying out a strike, is positioned at a spacing from the securing device 8 or its anvil 38. By loading the piston-cylinder unit 42, the striking member 40 is accelerated from below in the direction toward the securing device 8 and carries out a strike onto the securing device 8 when impacting the anvil 38. By means of this impact, an acceleration is exerted onto the securing device 8 wherein the shaft 35 is moved relative to the glide sleeve 29 with compression of the elastic rubber ring 36 in the direction 46 of the impact movement. Moreover, the holding-down device 15 is also moved in the upward direction by the upwardly moved securing device 8. The acceleration exerted onto the securing device 8 is transmitted onto the lens 6 so that the block 1 as a result of its inertia becomes detached from the lens 6. After the impact energy has been received by the spring-elastic bearing devices of the securing device 8 and of the holding-down device 15, the devices 8 and 15 return into their lower end position. In this connection, the securing device 8 is damped by the damping ring 34. The O-rings 23, 24 are provided for an additional gentle treatment of the lens 6.

[0029] When attaching a lens on a block, an outwardly projecting nose 43 (compare FIG. 6) can be produced on a peripheral location. In order to ensure a proper deblocking action despite of this nose, a slot 44 may be provided on the inner sleeve part 20 which extends in the axial direction across the length of the sleeve part 20. When loading the securing device 8, care must be taken that a nose 43 which may be present is positioned above this slot so that this nose 43 can move through this slot 44 when the block 1 drops. In the case that an automated loading device is provided, the lens which is gripped by a lens holder could be rotated, for securing the correct angular position of the nose 43, about a central longitudinal axis extending through the lens and the block until the nose of the block 1 rests against a stop which will position the nose properly.

[0030] Different modifications and alterations of the illustrated embodiment are conceivable and possible without leaving the realm of the invention. For example, the support of the securing device that is movable relative to a spring-elastic restoring force could also be realized in a different way then the one illustrated. For example, the shaft 35 of the securing device could also be attached to a bearing block on an elastic material which, in turn, is fastened on the frame of the carriage. The movement of the securing device 8 would then be realized against the elasticity of the material of the bearing block. Also, the bearing device 8, in place of the sleeve-shaped area on which the lens to be deblocking is supported, could have a support which is adjustable with regard to its diameter in order to be able to deblock lenses or blocks of different diameters with one and the same securing device. A securing device could be provided in the area of the support of the lens with several jaws surrounding a receiving opening for the block and positioned at a spacing from one another in the circumferential direction, wherein the diameter of the receiving opening is adjustable by scissor-type members, as disclosed already in the prior art deblocking device described supra.

[0031] In principle, it would also be conceivable and possible to eliminate the slide or carriage 7. The securing devices 8 would thus be stationary relative to the machine frame 11. In this situation, each securing device 8 would be provided with its own holding-down device 15 and its own striking device 39. Loading of one or several securing devices could be carried out by hand.

[0032] While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

Claims

1. A device for deblocking optical glasses attached to a block, the device comprising:

at least one securing device configured to support an optical glass and having an opening for a block suspended from the optical glass;

at least one holding-down device for pressing the optical glass supported on the securing device against the securing device;

at least one impacting device comprising a striking member movable from below against the securing device for striking the securing device;

wherein the securing device and the holding-down device are supported to be movable against a spring-elastic restoring force in a striking direction of the striking member.

2. The device according to claim 1, wherein the securing device has a sleeve-shaped upper area facing the optical glass supported thereon and configured such that the block suspended from the optical glass projects into an interior of this sleeve-shaped upper area and has a spacing to an inner wall of the sleeve-shaped upper area.

3. The device according to claim 2, wherein the securing device comprises a guide surface located underneath the sleeve-shaped upper area and extending downwardly, wherein the securing device has an ejection opening for the block separated from the optical glass and wherein the guide surface opens into the ejection opening.

4. The device according to claim 1, wherein the securing device has a lower side opposite the optical glass supported thereon and the lower side comprises an anvil for receiving a strike exerted by the striking member.

5. The device according to claim 4, wherein the anvil is arranged centrally underneath the lens or the block suspended therefrom.

6. The device according to claim 4, wherein the striking member has an initial position before carrying out a strike and is positioned in the initial position at a spacing from the anvil of the securing device.

7. The device according to claim 1, further comprising:

a glide sleeve, wherein the securing device is supported in the glide sleeve and is movable relative to the glide sleeve; and

a spring-elastic element configured to exert a restoring force upon movement of the securing device away from a lower end position.

8. The device according to claim 7, wherein the spring-elastic element is an elastic rubber ring fastened on the securing device and resting against an underside of the glide sleeve or a part that is connected to the glide sleeve.

9. The device according to claim 1, wherein the striking member has an initial position before carrying out a strike and is positioned in the initial position at a spacing from the securing device.

10. The device according to claim 1, wherein the striking device comprises a piston-cylinder unit and wherein the striking member is attached to a piston rod of the piston-cylinder unit.

11. The device according to claim 1, comprising a pneumatic piston-cylinder unit, wherein the holding-down device is fastened on a piston rod of the piston-cylinder unit.

12. The device according to claim 1, further comprising a moveable slide, wherein several of the securing devices are arranged on the slide, wherein the securing devices are moveable alternatingly into a position opposite the striking device.

13. The device according to claim the 12, further comprising an actuator for a program-controlled automated movement of the slide.

14. The device according to claim 1, wherein the optical glasses are spectacle lenses.