Patent Description:
During the fabrication of ophthalmic lenses, the semi-products are shaped and polished and part of the resulting powder (small particles of residues) remain in the tray. When referring to tray, any type of base, plate or container for placing on top the lenses is included as well. Focused on this problem, the literature shows different approaches:
In the document <CIT> the conveyor type cleaning device uses air supply pipes and suction nozzles directed to the object to be cleaned, which is tilted <NUM>° inside a cleaning chamber. It uses air instead of liquid, which may produce the powder to fly and keep suspended in the air inside the chamber and fall again on the tray. The medium directed to the tray should drag the powder away.

In the field of cleaning trays, the document <CIT> displays a machine with a conveyor that tilts the trays in a vertical direction and cleans them with a rinsing module. This process cannot be reproduced for lens trays because it considers neither that the dirty water falling from the prior tray affects the following tray nor that each tray is not as clean or dirty as the others, and the time and resources used should be particularized to each tray.

As it has been explained, the particular composition of the dust makes them very difficult to be removed from a tray, this is mentioned again in <CIT> which discloses a tray cleaning station in accordance with the preamble of claim <NUM>. In this document, a specific system of nozzles directed to the trays is developed to remove the stray lenses that get stuck to the plate. As it is explained in the document, it is necessary that the tray is as clean as possible to assure the quality of the following lenses placed on it.

The complexity of the task increases when the size of the lenses reduces, as they can remain stuck to the tray unnoticed. Therefore, the pressure applied to the tray by the cleaning medium (water) has to be much greater (around 20Pa). However, when such a large pressure is applied, another problem appears: the risk of propelling particles to the adjacent trays in a conveyor dirtying them, make it necessary to retire each tray from the line, clean it, and turn it back to the line.

Cleaning brushes cannot be used either as they will get quickly covered by powder particles and their cleaning capacity will be none, changing continuously the brushes means increasing prices and stopping the fabrication process too often.

When doing ophthalmic lenses, each lens is customized for a specific person, therefore the production line is very small and sensitive to errors. Moreover, the tools are precise and should take up a small room. Therefore, train-wash tunnels such as those disclosed in the prior art documents must be avoided, and an equivalent system is needed.

<CIT> discloses a system and a method for cleaning process trays. <CIT> discloses a method for cleaning workpiece carriers moving on conveyor belts and washing apparatus for carrying out the method. <CIT> discloses a case washing machine. <CIT> discloses a device for cleaning bottle cases.

For overcoming the mentioned drawbacks and achieve the afore mentioned aims, the present invention proposes a tray cleaning station for ophthalmic lenses production line, the tray cleaning station comprising a conveyor for the transport of trays supporting the lenses, which comprises extraction means of a tray from the conveyor, a chamber for cleaning the tray and transfer means of the tray between the extraction means and the chamber.

By separating or extracting the tray, dirt removed from the other trays does not affect the cleaning. We also avoid that, while cleaning a tray, the dirt does not reach the adjoining ones.

In addition, when removing only one tray each time it is possible to clean it with a suitable treatment according to its degree of dirt.

Another advantage of the station object of the invention is that it does not interfere in the line, since it washes the trays by extracting them from the circuit.

In a washing tunnel, sequential cleaning of all the trays is guaranteed. The installation of the invention does not ensure in a cycle the cleaning of all the trays, but that the washing of all the trays ends up ensuring by accumulation of cycles. Obviously, theoretically there is a non-null possibility that a tray will never be extracted. However, as indicated below, means can be provided to prevent this from happening, such as visual inspection, either by an operator or artificial vision, which allows to detect trays that have accumulated dirt due to lack of washing. In any case, the skilled person, by means of probability calculations, will determine the necessary frequency of visual inspection of the line to guarantee that all the trays end up being cleaned.

In accordance with the invention, the extraction means comprise a rotating base which supports two arms, each provided in its end with a pad destined to press laterally a tray, a rotation axis of the rotating base, and an actuator for rotating the axis, the rotating base being provided with a linear actuator for adjusting the distance between the arms, thus allowing to clamp a tray between the pads.

In some embodiments, the transfer means comprise two clamping arms, each provided in its end with a pad, a translating base which supports the clamping arms, and a guide for the translational movement of the translating base, the translating base comprising a linear actuator for adjusting the distance between the clamping arms, thus allowing to clamp a tray between the pads.

In some embodiments, the pads of the arms of the rotating base are arranged to clamp the trays on two sides of the trays and the pads of the clamping arms are arranged to clamp the trays on the other two sides of the trays.

In some embodiments, the extraction means are configured to carry out a rotation having an angle greater than 90º, thus allowing to overturn a tray.

In some embodiments, the chamber comprises a vertical slot for introducing the tray.

This feature, combined with the translatory movement provided by the transfer means allows the tray to be arranged vertically, which is the optimum position for cleaning and drying the tray.

In some embodiments, the chamber comprises at least two air conducting ducts vertically arranged and at least two water conducting ducts vertically arranged.

Thus at least two curtains of water and air for cleaning the tray are created.

In some embodiments, the air conducting ducts and the water conducting ducts are arranged such that they define therebetween a vertical slot coincident with the vertical slot, the transfer means being arranged to introduce the tray through the vertical slot and place it between the air conducting ducts and the water conducting ducts.

With the same movement of translation, it is possible to introduce the tray in the camera and then between the air and water conduits.

In some embodiments, the chamber comprises a sliding door destined to close the vertical slot, and actuator means for automatically closing the sliding door, the sliding door and the chamber comprising recesses for allowing the introduction of the clamping arms, thus allowing to close the chamber when a tray is being washed and move it in translational movement for exposing all its surface to the nozzles.

With a closed chamber, contaminating of the other trays is avoided.

In some embodiments, the pads comprise adjusting means for adjusting the distance therebetween.

Thus it is possible to use trays of different sizes and suppliers.

In some embodiments, the tray cleaning station comprises one reservoir arranged below the ducts.

In other embodiments, the tray cleaning station comprises two reservoirs arranged below the ducts and a deflector allowing to deflect the water falling to either of the reservoirs. Thus it is possible to reuse the water and save it.

In some embodiments, the tray cleaning station comprises a pump for pumping water in the chamber at a pressure comprised between <NUM> and <NUM> bar.

It has been determined that these pressures are suitable for cleaning the dirt from the machining (oils, shavings) and removing from the trays the polishing dust.

In some embodiments, the tray cleaning station has a controller, the controller being configured to apply different cleaning programs.

The invention also relates to a production line for manufacturing ophthalmic lenses provided with treatment stations connected by at least one conveyor for the transport and transfer, between stations of trays supporting the lenses, the production line comprising at least one tray cleaning station according to any of the variants of the tray cleaning station.

Preferably, the cleaning station is configured to be always cleaning a tray, autonomously and automatically, without the need for an operator.

To complete the description and in order to provide a better understanding of the invention, a set of drawings is provided. Said drawings form an integral part of the description and illustrate embodiments of the invention, which should not be interpreted as restricting the scope of the invention, but just as an example of how the invention can be carried out.

As shown in <FIG>, <FIG> and <FIG>, according to a preferred embodiment, herein it is disclosed a tray cleaning station W for ophthalmic lenses production lines LP.

A line as such is schematically shown in <FIG>.

The tray cleaning station W comprises a conveyor T for the transport of trays B supporting the lenses, extraction means X of a tray B from the conveyor T, a chamber CH for cleaning the tray B and transfer means TR of the tray B between the extraction means X and the chamber CH.

The operation is simple: instead of making all the trays B to pass through a cleaning tunnel, the present invention takes out one tray from the conveyor T by using the extraction means. Then, the tray is transferred from the extraction means to the transfer means, which introduces the tray T in the cleaning chamber CH.

According to the embodiment shown in <FIG>, <FIG> the extraction means X comprise a rotating base BX which supports two arms X1, X2.

Each arm X1, X2 is provided in its end with a pad P1, P2 destined to press laterally a tray B.

As shown in <FIG> and <FIG>, the base BX rotates around a rotation axis Γ driven by an actuator DX for rotating the axis Γ.

The rotating base BX is provided with a linear actuator (not shown) for adjusting the distance between the arms X1, X2, thus allowing to clamp a tray B between the pads P1, P2 and then raise it by rotating the arms around the axis Γ.

As shown in <FIG>, the transfer means TR comprise two clamping arms TR1, TR2, each provided in its end with a pad TR3, TR4. The operating principle is similar as for the extraction means X.

The clamping arms TR1, TR2 are supported by a translating base TRS, which is guided by a guide G according to a translational movement.

To that end, the translating base TRS comprises a linear actuator for adjusting the distance between the clamping arms TR1, TR2, thus allowing to clamp a tray B between the pads P3, P4.

The pads P1, P2 of the arms X1, X2 of the rotating base BX are arranged to clamp the trays B on two sides of the trays B and the pads TR3, TR4 of the clamping arms TR1, TR2 are arranged to clamp the trays B on the other two sides of the trays B, thus allowing a simple transfer from the rotating to the translational means.

A special feature of the invention is that the extraction means X are configured to carry out a rotation having an angle greater than 90º, thus allowing to overturn a tray B and void it form gross objects that could be accidentally present therein. A recollecting tray RB is placed on the other side of the axis Γ with respect to the conveyor T, thus allowing to collect the objects falling from the overturned tray B.

Then, the tray B is placed vertically, as shown in <FIG>, then ready to be inserted in a vertical slot VS for introducing the tray B into the chamber CH.

As shown in <FIG>, the chamber CH comprises at least two air conducting ducts W1 vertically arranged and two sets of water conducting ducts W2 vertically arranged.

These air conducting ducts W1 and the water conducting ducts W2 are arranged such that they define therebetween a vertical slot coincident with the vertical slot VS, the transfer means TR being arranged to introduce the tray B through the vertical slot VS and place it between the air conducting ducts W1 and the water conducting ducts W2.

The chamber CH is completed with a sliding door SD destined to close the vertical slot VS, and actuator AD means for automatically closing it.

To tightly close the chamber, the sliding door SD and the chamber CH comprise recesses S1, S2 for allowing the introduction of the clamping arms TR1, TR2, thus allowing to close the chamber CH when a tray B is being washed and move it in translational movement for exposing all its surface to the nozzles, as shown for example in <FIG>.

Since different production lines can use different tray formats, the pads comprise adjusting means AM for adjusting the distance therebetween. These adjusting means can have the form of screws.

The station comprises at least a reservoir D1 below the chamber, arranged to collect the cleaning liquids.

As shown in <FIG>, optionally the station comprises two reservoirs D1, D2 arranged below the ducts W1, W2 and a deflector D allowing to deflect the water falling to either of the reservoirs D1, D2.

The station comprises a pump for pumping water in the chamber CH at a pressure comprised between <NUM> and <NUM> bar. These pressures have proven to be effective to efficiently remove the dirt and the dust adhered to the trays B.

One of the major advantages of the inventive station is that it allows to apply different cleaning programs to each tray B depending on its dirt degree. To that end, the station is provided with a controller, the controller being configured to apply different cleaning programs.

The station can be provided with means for detecting the state of dirt of the trays B. These means can be based for example in an artificial vision system, or a reader of tags indicating the state of dirt of the trays B, that could have been placed/ adhered to the trays in a previous stage, either manually or automatically.

The station has been specially conceived for its integration in a production line LP for manufacturing ophthalmic lenses L provided with treatment stations ET, as shown in <FIG>.

The production line has treatment stations, for example polishing stations, connected by at least one conveyor T for the transport and transfer of trays B supporting the lenses L. According to the present invention, one of the stations is a tray cleaning station W according to any of the variants disclosed above.

An important aspect of the invention, as can be seen in the figures, is that all the components of the station are easily accessible for maintenance, both to clean and to fix them. These tasks are usually much more complicated in a washing tunnel.

According to a preferred aspect of the invention, the cleaning station is configured to be always cleaning a tray B.

That is to say, instead of cleaning the trays in a tunnel, with the inconveniences that this entails, here we opt for a station arranged in parallel, that is, that takes out trays of the line and cleans them. The station is set to always be cleaning a tray. That is to say that it does not clean all the trays that go through the conveyor, but as soon as a tray has just been cleaned, the next tray that can be taken is extracted from the conveyor.

Obviously, that does not mean that all the trays are cleaned consecutively, as would happen in a tunnel. It is also obvious that there is a non-zero probability that a tray in a certain time interval does not end up being cleaned.

However, it is advantageously provided that the station has means for recognizing a dirt indicator of the tray, which may be a label previously adhered by an operator or an artificial vision system to finish cleaning trays that are travelling in the conveyors without being cleaned.

The invention also relates to a method of washing trays in a ophthalmic lenses production line LP, which comprises the steps consisting of:.

In this text, the term "comprises" and its derivations such as "comprising", etc. should not be understood in an excluding sense, that is, these terms should not be interpreted as excluding the possibility that what is described and defined may include further elements.

Claim 1:
Tray cleaning station (W) for ophthalmic lenses production line (LP), the tray cleaning station (W) comprising a conveyor belt (T) for the transport of trays (B) supporting the lenses, comprising extraction means (X) of a tray (B) from the conveyor belt (T), a chamber (CH) for cleaning the tray (B) and transfer means (TR) of the tray (B) between the extraction means (X) and the chamber (CH), characterized in that the transfer means are configured to introduce the tray (T) in the cleaning chamber (CH) and wherein the extraction means (X) comprise a rotating base (BX) which supports two arms (X1, X2), each provided in its end with a pad (P1, P2) destined to press laterally a tray (B), a rotation axis (Γ) of the rotating base (BX), and an actuator (DX) for rotating the axis (Γ), the rotating base (BX) being provided with a linear actuator for adjusting the distance between the arms (X1, X2), thus allowing to clamp a tray (B) between the pads (P1, P2).