EP2954989A1

EP2954989A1 - Coolant-filtering apparatus for lens-processing machine tolls

Info

Publication number: EP2954989A1
Application number: EP14002009.0A
Authority: EP
Inventors: Leo Sciarappa
Original assignee: La Chiara Srl; ROM SpA
Current assignee: La Chiara Srl; ROM SpA
Priority date: 2014-06-11
Filing date: 2014-06-11
Publication date: 2015-12-16

Abstract

A tank (24) receives coolant contaminated with machining residues from a machine tool (10). Filtering means filter the coolant, with separation of the machining residues. A pump (52) sucks the coolant from the tank (24) downstream of the filtering means and recirculates it to the machine tool (10). The filtering means comprise a fine-mesh, hollow filtering member (51) submerged in the tank (24). The pump (52) sucks coolant from the inside of the hollow filtering member (51). A collecting channel (28) formed on the bottom of the tank (24) houses a first motorized auger (32) which conveys the machining residues to an outlet section of the collecting channel (28). A transfer duct (38) houses a second motorized auger (36) which conveys the machining residues to a level higher then a maximum filling level (F) of the tank (24). The second auger (36) is provided with a shaft (36s) increasing in diameter from its inlet end to its outlet end for applying a drying squeezing action to the machining residues.

Description

The present invention relates to a coolant-filtering apparatus for lens-processing machine tools, with particular reference to ophthalmic lenses for eyeglasses.
As known, the raw lenses for eyeglasses generally have a circular profile, and can be shaped into a profile matching with the frame of the eyeglasses by chip removal processes, e.g., milling or grinding.
In the past, after that the user of the eyeglasses had chosen the lenses and possibly the frame in an optical shop, the lenses were normally sent to an external optical laboratory equipped with dedicated machine tools designed to be used by specialized personnel, where the shaping was carried out.
However, compact, intuitive lens-processing machine tools, or machines, have recently become widespread, which are designed to be directly installed in the optical shop in order to be used by the personnel of the shop.
The above compact machines, like most of the machine tools for chip removal processing, are provided with a hydraulic circuit which, during machining, ejects a (liquid) coolant into the area of contact between the lens and the tool for lubrication/refrigeration purposes. The coolant contaminated with the machining residues falls into a tank arranged below the machine, where it is filtered and recirculated by a pump which is conventionally submerged in the tank.
A known filtering system provides filtering the coolant through a permeable collecting bag which is adapted to retain the machining residues. Once full, the collecting bag is removed and replaced by an empty one.
However, the above known filtering system has some drawbacks.
In particular, filtering through a permeable collecting bag has a low effectiveness. In fact, the coolant recirculated by the pump still contains residues in the shape of chip dust which are too fine to be retained by the collecting bag. Such residues may easily generate encrustations on the tool and, more generally, in the machining area over time.
Moreover, the above filtering system is not handy in relation to the disposal of the machining residues, especially in view of the fact that the optical shops, in contrast to specialized optical laboratories, normally are not structured to deal with these issues. In particular the collecting bag, when full, comes as a heavy, dripping bundle soaked with water, which is very inconvenient to handle for the personnel of the shop.
In addition, the pump submerged in the tank is usually very noisy. This circumstance makes the above filtering system not only wearing to use but also difficult to position in an optical shop.
Therefore, it is a main object of the present invention to provide a coolant-filtering apparatus for compact, lens-processing machine tools, which has a higher filtering effectiveness, which makes it easier and more handy the disposal of the machining residues, and which is also less noisy with respect to the known filtering systems with submerged pump.
The above objects and other advantages, which will better appear from the following description, are achieved by the filtering apparatus having the features recited in claim 1, while the dependent claims state other advantageous, though secondary features of the invention.
The invention will be now described in more detail with reference to a few preferred, non-exclusive embodiments, shown by way of non-limiting example in the attached drawings, wherein:

Fig. 1 is a diagrammatical view of a lens-processing compact machine having a coolant-filtering apparatus associated therewith;
Fig. 2 is a perspective view of the coolant-filtering apparatus according to the invention;
Fig. 3 is a perspective view of the internal components of the coolant-filtering apparatus of Fig. 2;
Fig. 4 is a perspective view of the coolant-filtering apparatus according to the invention from a different viewpoint with respect to Fig. 2;
Fig. 5 is a view in side elevation of the coolant-filtering apparatus according to the invention;
Fig. 6 is a view in cross-section of the coolant-filtering apparatus according to the invention;
Fig. 7 is a perspective view showing a few assembled components of the coolant-filtering apparatus according to an alternative embodiment of the invention;
Fig. 8 is a perspective view isolately showing one of the components of Fig. 7 in cross-section.

A compact machine 10 for processing ophthalmic lenses for glasses is diagrammatically shown in Fig. 1. Machine 10 is of a type suitable for being installed in an optical shop in order to be used by the personnel of the shop.
In a way known per se, machine 10 has a machining area 12 in which chip removal processes are carried out on a raw ophthalmic lens L. Machine 10 is provided with a control interface 13 by which the user controls the processes on the lens.
During machining, the area of contact between lens L and tool T is hit by a stream of coolant C delivered by a hydraulic circuit 18 incorporated in machine 10. The coolant contaminated with machining residues R is discharged, via a discharge tube 19, into a filtering apparatus 20 arranged below machine 10 and, after filtering, is recirculated into hydraulic circuit 18.
Filtering apparatus 20, which is the object of the present invention, comprises a tank 24 having a rectangular profile, with a first side wall 24a and an opposite, second side wall 24b, a rear wall 24c and an opposite front wall 24d, and a V-shaped bottom 26 culminating in a collecting channel 28 having a profile of an arc of circle, which extends from first side wall 24a to second side wall 24b parallel to rear wall 24c and front wall 24d. Tank 24 lies on a support plate 29 via feet such as 24e. Collecting channel 28 leads, with an outlet section thereof, to an outlet opening 30 formed on second side wall 24b. A first auger 32 is rotatably supported within collecting channel 28. First auger 32 has a first gear 34 operatively connected thereto outside first side wall 24a.
A second auger 36 is rotatably supported in a tube 38 arranged outside tank 24 adjacent to second side wall 24b. Tube 28 obliquely extend from the bottom of tank 24 to a balcony 37 which projects outwards from rear wall 24c of tank 24 at a level higher than a maximum filling level F of tank 24. In particular, tube 38 has a lateral inlet mouth 38a which is connected to outlet opening 30, and a lateral outlet mouth 38b which opens into the inside of balcony 37. Second auger 36 has a second gear 43 operatively connected thereto outside the inlet end of tube 38.
An extraction duct 44 extends horizontally within balcony 37 from lateral outlet mouth 38b to first side wall 24a. A third auger 46 is rotatably supported within extraction duct 44. Third auger 46 has a third gear 48 operatively connected thereto outside first side wall 24a. A vertical discharge branch 50 projects downwards from an intermediate section of extraction duct 44. A disposable collecting bag (not shown) may be connected to the outlet of discharge branch 50.
A fine-mesh, hollow cylindrical filter 51 is supported with horizontal axis between first side wall 24a and second side wall 24b. Cylindrical filter 51 advantageously has a mesh size in the range 1 to 10 µm, preferably 5µm. A pump 52 supported on support plate 29 below tank 24 has a suction line 52a operatively connected to the inside of cylindrical filter 51, and a delivery line 52b connected to the inlet of hydraulic circuit 18.
Filtering apparatus 20 is also advantageously provided with a filter-cleaning unit 56.
Filter-cleaning unit 56 comprises three parallel, rectilinear brushes 58 which are supported about the axis of cylindrical filter 51 at equally-spaced angular positions, by a rings 60. Brushes 58 are put in contact with the outer wall of cylindrical filter 51 and are adapted to be driven to rotate about the axis of the latter. To this purpose, they have a fourth gear 64 operatively connected thereto outside first side wall 24a.
For an even more effective cleaning of the filter, pump 52 is also advantageously provided with means for its actuation in backpressure.
First auger 32, third auger 46 and filter-cleaning unit 56 are driven to rotate by a motorized chain 66, which is driven by a gearmotor 68 with pinion 68a which respectively engages first gear 32, third gear 48 and fourth gear 64. Gearmotor 68 is also supported on support plate 29 below tank 24. Second auger 36 is also driven to rotate by a couple of chain drives 69a, 69b, which are interconnected in series via a bevel gear pair 69c and connect gearmotor 68 to second gear 43.
At least second auger 36 and, preferably, also third auger 46 are provided with respective frustoconical shafts 36s, 46s which increase in diameter from their inlet ends to their outlet ends, in order to apply a drying squeezing action to the material.
Advantageously, a removable, large mesh sieve 72 is supported on the top of tank 24 for preliminarily and roughly sieving the coolant discharged from machine 10.
The filtering apparatus may be covered by a shell which is not shown for better clarity.
The operation of the filtering apparatus is advantageously controlled by a control unit (not shown) which may be programmed to perform filtering cycles which may be carried out alternately to, or simultaneously with, cleaning cycles carried out by either filter-cleaning unit 56 or backpressure. Alternatively, the filtering cycles and the cleaning cycles may be actuated manually. The programming of the control unit, if any, falls within the normal knowledge of the person skilled in the art and therefore will no be discussed herein.
The operation of coolant-filtering apparatus 20 will be now described.
The coolant discharged from machine 10 into tank 24 first passes through sieve 72, which retains the largest chip pieces. When sieve 72 is full, it can be removed, then emptied, and finally repositioned on the tank.
The coolant in tank 24 is suctioned by pump 52 through cylindrical filter 51 and then recirculated into hydraulic circuit 18. Cylindrical filter 51 is even capable of retaining the finest machining residues in virtue of the fineness of its mesh.
The machining residues retained by cylindrical filter 51 are deposited on V-shaped bottom 26 of the tank and then enter collecting channel 28. First auger 32 conveys the machining residues into tube 38 through outlet opening 30. Second auger 36 conveys the machining residues into extraction duct 44. It should be noted that an end portion of tube 38 extends above the maximum filling level F of tank 24; this circumstance helps the machining residues be dried, in combination with the frustoconical shape of the shafts of first auger 32 and second auger 36, which has the effect of squeezing the material. It has been found in practice that the material delivered from tube 38 has a degree of humidity very low, i.e., it is almost dry. Third auger 46 discharges the machining residues into discharge branch 50. Through the latter, the residues fall into the collecting bag. When the collecting bag is full, the user removes it and replaces it with an empty one.
Figs. 7 and 8 show an alternative embodiment of the invention which differs from the previous one in the following aspects.
The third auger is absent and second auger 136 discharges the material directly into a first drawer 174 arranged below second auger 136 and lying on a frame 175 which supports tank 124. Accordingly, first drawer 174 is adapted to receive the fine residues.
Moreover, tank 124 is closed on the top by a cover 176 having a chute 178 defined thereon which has a profile that narrows towards its bottom end. Chute 178 leads into a second drawer 180 which is received in a recess 182 defined on rear wall 124c of tank 124, through a passage 184 formed on cover 176 at the bottom end of chute 178. Recess 182 has a support base 186 which is open to the inside of the tank in 187. Second drawer 180 has a perforated bottom and 180a and, substantially, performs the task which in the previous embodiment was performed by sieve 72.
With this embodiment, the coolant from the machine is discharged on chute 178 and then into second drawer 180 through passage 184. Second drawer 180 retains the largest chip pieces while the liquid with the finest residues falls into the tank through the perforated bottom of second drawer 180 and the open support base 186.
A few preferred embodiments of the invention have been described herein, but of course many changes may be made by a person skilled in the art within the scope of the claims. For example, depending on the frequency of use of the machine, the cylindrical filter could also be cleaned manually, or cleaning systems different from the above-described ones could be provided, e.g., shaking or vibrating systems. Of course, in the first embodiment, chain drives 66, 69a and 69b could be replaced by any other drive using a flexible, annular drive member, such as a belt drive. Alternatively, depending on the requirements, each of the rotary components may be driven by its own motor, or some of the components may be driven simultaneously by a single motor, other components by their own dedicated motors.

Claims

A coolant-filtering apparatus for lens-processing machine tools, comprising
a tank (24) adapted to receive coolant contaminated with machining residues from a machine tool (10),
filtering means operatively arranged to filter said coolant with separation of said machining residues,
a pump (52) operatively arranged to suck said coolant from the tank (24) downstream of said filtering means, and to recirculate it to said machine tool (10),
characterized in that said filtering means comprise
a fine-mesh, hollow filtering member (51) submerged in said tank (24), said pump (52) being connected to suck coolant from the inside of said hollow filtering member (51),
a collecting channel (28) defined on the bottom of said tank (24) for receiving said machining residues,
a first motorized auger (32) received within said collecting channel (28) for conveying said machining residues to an outlet section of the collecting channel,
a transfer duct (38) having an inlet mouth (38a) connected to said outlet section of the collecting channel (28), and a outlet mouth (38b) defined at level higher then a predetermined maximum filling level (F) of the tank (24),
a second motorized auger (36) which is received within said transfer duct (38) for conveying said machining residues from said inlet mouth (38a) to said outlet mouth (38b),
said second auger (36) being provided with a shaft (36s) increasing in diameter from its inlet end to its outlet end for applying a drying squeezing action to said machining residues.
The coolant-filtering apparatus of claim 1, characterized in that said transfer duct comprises a tube (38) arranged outside of said tank (24).
The coolant-filtering apparatus of claim 1 or 2, characterized in that said bottom (26) has a V-shape which culminates into said collecting channel (28).
The coolant-filtering apparatus of any of claims 1 to 3, characterized in that said hollow filtering member (51) has a mesh size in the range 2 to 10 µm.
The coolant-filtering apparatus of claim 4, characterized in that said mesh size is 5 µm.
The coolant-filtering apparatus of any of claims 1 to 5, characterized in that it comprises filter-cleaning means (56).
The coolant-filtering apparatus of claim 6, characterized in that said hollow filtering member (51) has a cylindrical profile, and said filter cleaning means (56) comprise at least one brush (58) which is put in contact with the outer wall of the hollow filtering member (51) and is connected to motor means to rotate about the axis of the hollow filtering member (51).
The coolant-filtering apparatus of claim 6, characterized in that said filter-cleaning means (56) comprise means for the actuation in backpressure of said pump (52).
The coolant-filtering apparatus of any of claims 1 to 8, characterized in that it comprises a third motorized auger (46) which is received within an extraction duct (44) connected to said outlet mouth (38b) of the trasfer duct (38) and having an outlet (50) for discharging said machining residues.
The coolant-filtering apparatus of any of claims 1 to 9, characterized in that it comprises a large mesh sieve (72) arranged to carry out a rough preliminary sieving on the coolant discharged from said machine tool (10).
The coolant-filtering apparatus of any of claims 1 to 9, characterized in that a chute (178) is supported on the top of said tank (124) for guiding the coolant discharged from said machine tool into a drawer (180) received in a recess (182) formed on the tank and having a support base (186) which is open (187) to the inside of the tank, said drawer (180) having a perforated bottom (180a) for a rough preliminary sieving of the coolant.