WO2003068422A1

WO2003068422A1 - Device and method for washing container-gripping elements

Info

Publication number: WO2003068422A1
Application number: PCT/EP2003/001364
Authority: WO
Inventors: Matteo Zoppas; Marco Leonardi; Andrea Saran; Paola Tamagnone
Original assignee: SIPA Industrializzazione Progettazione e Automazione SpA
Current assignee: SIPA Industrializzazione Progettazione e Automazione SpA
Priority date: 2002-02-13
Filing date: 2003-02-12
Publication date: 2003-08-21
Anticipated expiration: 2004-08-13
Also published as: ITRM20020079A1; AU2003218985A1; ITRM20020079A0

Abstract

A device (1) for washing conveyor chains (5) and/or plastic-bottle-gripping chucks (6) comprising a washing tank (7) filled with washing liquid into which the chain s and the chucks are immersed during the washing operation that takes place in a segment of the travel path of the bottles. The tank (7) is equipped with ultrasound generators (14, 15) positioned on the walls and on the bottom. The washing device also comprises a spray pre-washing area (3) and a spray rinsing area (4).

Description

DEVICE AND METHOD FOR WASHING CONTAINER-GRIPPING ELEMENTS Technical Field

This invention relates to a device for washing a conveyor chain and its elements for gripping containers, for example plastic bottles, after said chain and elements have been dirtied with paint or other products used to coat the containers at a coating station. Background Art

Today, the production of containers in different shapes and sizes for foodstuff - for example plastic bottles or pots made of PET, PP, HDPE, or PEN - normally involves a process comprising a blow-moulding phase to create the container in its final form, starting from a pre-moulded workpiece produced by means of injection, compression, or other type of moulding. In special cases, the blow-moulding phase is followed by a coating operation using products particularly suited to make the container gas-tight, such as to oxygen or carbon dioxide. The question of the permeability of the container walls to gas is particularly important, for example, when dealing with bottles that must contain carbonated drinks, but also in the case of other foodstuff or drinks that are affected by oxidation, decreasing shelf life. The coating plants can be of very different sizes, also depending on the productive capacity of the plant that can vary from hundreds to several thousands of bottles per hour. Today, these plants are highly automated; they comprise a station for loading the containers to be painted, a coating station, and a paint reticulation station (for example, equipped with furnaces suitable for the type of paint used in the process). In these plants, containers are moved from one station to another by means of conveyor chains equipped with gripping devices or on conveyor belts. Normally, the coating plants also include a washing station or a station for cleaning the gripping devices, such as chucks or grippers, and the conveyor chain that get dirty during coating. Coating can be of two types: spray coating with spray nozzles, or immersion in dipping tanks full of paint. A problem that generally arises with these plants is the difficulty in removing paint residues from the chain and from the bottle-gripping devices, especially after the paint or the coating has dried or has started to reticulate or, worse still, after drying in furnaces when required by the chosen coating process. In the long term, dried paint residues on the gripping devices and on the chain - which usually involve moving parts - negatively affect the performance of said devices and increase wear, which increases running costs besides increasing downtime due to maintenance work. Furthermore, there is a risk of contamination of the bottles before coating when they are grabbed by the gripping devices, which are coated with the paint residues. Sometimes, the inside of the bottle is contaminated: for example, when a gripping device of the chain does not grab a bottle; consequently, the parts of the gripping device that normally are in contact with the inside of the neck of the bottle, which should never be dirty of paint, are also coated, contaminating subsequently gripped bottles. When this occurs, the internally contaminated bottle or container must be carefully inspected and rejected since the paint is not fit to come into contact with the drink or foodstuff to be packaged in the container. One of the solutions recommended in the past to overcome these problems is to include washing or cleaning stations along the circuit of the conveyor chain. However, to date, these devices have not given fully satisfactory results, especially when the coating plant has a high hourly production rate; in this case, the conveyor chain must have a high feed rate, and, consequently, the washing devices must also have a large productive capacity. There are no known compact washing devices that are able to wash conveyor chains accurately that move at high rates. Objects of the Invention

It is an object of this invention to provide a device for washing conveyor chains and gripping devices of containers, such as bottles, that resolves the aforementioned problems, contributing to improve the quality pf the coating processes, even in coating plants with a high hourly output. It is another object of the invention to create a washing device that requires less upkeep and minimizes the contamination of the containers to be coated. It is another very important object of the invention to make a washing device that is. compact in size and economical to run.

These objects, in accordance with a first aspect of the invention, are achieved by means of a device for washing conveying and/or gripping devices of containers, especially plastic bottles, operating along a specific travel path comprising at least one pre-washing area, washing area, and rinsing area. Said washing area comprises a tank suitable to contain a washing liquid into which said conveying and/or gripping devices are immersed during a washing operation carried out in a specific segment of said travel path; the tank also comprises ultrasound generators positioned on the walls and on the bottom, suitable to be operated during said washing operation.

In accordance with another aspect of the invention, these objects are achieved with a method for washing the conveying and/or gripping elements of containers, especially plastic bottles, implemented by means of the washing device as claimed in one of the previous claims, comprising the steps of: a) feeding said conveying and/or gripping devices of containers into said washing device from the pre-washing area b) spraying said conveying and/or gripping devices with a pre-washing detergent liquid in said pre-washing area c) feeding said conveying and/or gripping devices into the washing tank containing a washing liquid, immersing them up to a predetermined level d) emitting ultrasounds of predetermined intensity by ultrasound generators positioned on the walls and on the bottom of said washing tank e) at the end of a predetermined amount of time, feeding said conveying and/or gripping devices into a rinsing area where they are rinsed with a rinsing liquid Thanks to the innovative characteristics of the washing device in accordance with the invention, the device is suitable for washing chains and gripping devices - such as chucks, grippers, or similar - in a compact space and quickly. The ultrasound system assures the accurate cleaning of all the elements that pass through the coating stations.

The washing station can be placed in different points of the coating plant: directly after the coating station, in which case the containers are removed just after said coating station and sent to another processing circuit; or after the forced-drying or air-drying area in the case of a single conveying circuit.

In the former type of setup, the conveyor chains are divided into two separate circuits, the so-called wet and dry circuits, and the circuit that goes through the coating stations, meaning the wet circuit, does not go through the drying furnace. This option has the added advantage of facilitating and making more economical the cleaning operation of the container-gripping devices dirtied during each cycle, since the paint does not have the time to reticulate. Normally, the presence of an in-line washing station, whether it is placed in a wet area separate from the dry area or after the dry area, leads to less machine downtime for maintenance work or for replacing the gripping devices that are too soiled or worn out. Brief description of the drawings Other advantages of the invention will be readily apparent from the more detailed description of a particular version of the washing device, given as a nonlimiting example and in conjunction with the following accompanying drawings: Fig. 1 shows a longitudinal section of the first version of a washing device in accordance with the invention Fig. 2 shows a cross section of the washing device of Fig. 1

Fig. 3 shows a plan view with partial sections of the washing device of Fig. 1 Detailed description of the invention

The aforementioned figures show a washing device, hereinafter also referred to as reference 1, comprising a central washing area (2) and a tank (7) containing an appropriate detergent liquid - normally a solvent suitable to dissolve the type of paint or product used in the coating process - during operation. Furthermore, the device includes a pre-washing area (3) positioned before the washing area (2), and a rinsing area (4) positioned after the washing area (2). The conveyor chain (5) is equipped with the container-gripping elements, the so-called chucks (6) or other similar gripping devices, and travels along the predetermined path before going through the pre-washing area (3), then through the washing area (2), and, finally, through the rinsing area (4).

The washing area (2) features a system for generating ultrasounds that are directed at the fed-through chain segment and at the gripping devices. Defining appropriately the ultrasound generating parameters, also depending on the type of paint used in the coating process and the solved found in the washing tank (7), results in optimal washing of the components that pass through the device (1 ). As a function of these parameters, it is possible to define the operating frequency of the washing device, which can be used at every passage of the chain or at specific time intervals definable through testing. The ultrasound generating system amplifies the cleansing power of the liquid; it requires ultrasound generators (14, 15) to be positioned at the bottom and on the sides of the washing tank (7). The cleansing action is more effective if the sides of the tank (7) are placed at an angle in relation to the vertical direction, so that they get nearer in the bottom area. The external walls of the washing device (1 ) can be appropriately soundproofed in order to reduce environmental noise levels. The pre-washing area (3), preferably in the form of a channel that leads into the washing tank (7), features a spray-pre-washing device.

The rinsing area (4) is also equipped with spray nozzles (9) that spray the solvent onto the chain to eliminate any residues left on the chain (5) and on the chucks (6). This area can also feature spray tunnels or similar devices. Iri a preferred version of the invention, the pre-washing, washing, and rinsing operations are carried out with the same solvent liquid. In special versions of the invention for special paints, the aforesaid three operations can be carried out with different products. Preferably, but not necessarily, the washing tank (7) is placed at a level lower than the pre-washing (3) and rinsing (4) areas. In this case, the conveyor chain is a two-planar chain that bends on two planes that are orthogonal to each other. Some ducts (8 and 8') for supplying the spray nozzles of the pre-washing and washing areas are required in all areas of the washing device (1 ); the ducts are supplied by pumps (11) from a container (10) filled with washing liquid. The container (10) is also fed by overflow ducts (not shown in the figures) that dump any excess washing liquid from the washing tank (7). Appropriate filters (12) are required in the delivery ducts.

If required by the washing process, the container (10) can feature known heaters for heating the detergent liquid. A drying device (13) equipped with compressed-air and/or hot-air jets or room- temperature fans can be placed after the rinsing area (4). Height-adjustable mechanisms (not shown in the figures) for lifting from the floor the part of the device (1) comprising the pre-washing, washing, and rinsing areas allow the device to be adjusted to the different heights of the conveyor chain, making it possible to choose how much of the chain and chucks are immersed into the liquid during washing or whether to use the entire washing device on the chain. In this case, the lifting mechanism can lower the entire device outside the immersion area of the chain.

The use of the washing device (1) to wash the chain is carried out as specified below. During the advancement of the conveyor chain, when the washing process of the gripping devices starts, the washing device (1 ) is lifted to the height of the feeding line of the chain in order to immerse the gripping devices into the liquid contained in the tank (7) up to a certain level.

The chain (5) and the chucks (6) are sprayed in the pre-washing station (3) with an appropriate detergent liquid suitable to prewash. Then, the chain is fed into the washing tank (7) that is filled up to a predetermined level with detergent liquid suitable for washing, and is fitted with ultrasound generators of determined intensity. After a predetermined amount of immersing time, dependent on the type and condition of the paint that contaminates the chain and gripping devices, that can be adjusted by defining the feed rate of the conveyor chain and/or by defining the length of the different areas of the device (1), the chain emerges from the washing tank (7). Then, said chain travels through a rinsing area (4) where, using jets or spray nozzles, any remaining paint residues are removed with the rinsing liquid. Finally, the chain travels through a forced or natural-evaporation drying area. The washing detergent liquid is filtered, regenerated, and, after a predetermined amount of use, replaced.

Claims

1. A device (1 ) for washing conveying (5) and/or gripping (6) devices of containers, especially plastic bottles, that travels along a predetermined path comprising at least a pre-washing area (3), a washing area (2), and a rinsing area (4); said washing area (2) comprising a tank (7) suitable for containing a washing liquid into which said conveying (5) and/or gripping (6) devices are immersed during a washing operation carried out in a specific segment of said travel path; said tank (7) being fitted with ultrasound generators (14, 15) positioned on the walls and on the bottom suitable for operating during said washing operation

2. A device as claimed in claim 1 wherein said washing tank (7) is positioned at a lower level than the level of said pre-washing (3) and rinsing (4) areas.

3. A device as claimed in claim 2 wherein said pre-washing (3) and rinsing (4) areas comprise means for spraying their respective pre-washing and rinsing fluids.

4. A device as claimed in claim 3 wherein said respective pre-washing and rinsing fluids consist of the same product, identical to said washing liquid.

5. A device as claimed in claim 3 wherein said respective pre-washing and rinsing fluids consist of different products, which are different from said washing liquid.

6. A device as claimed in one of the previous claims wherein the rinsing area (4) comprises a spray tunnel for supplying the rinsing liquid.

7. A device as claimed in one of the previous claims wherein recycling and/or filtering and/or regenerating means of said one or more washing, pre-washing, and rinsing fluids are included.

8. A washing method of conveying (5) and/or gripping (6) devices of containers, especially of plastic bottles, implemented by means of the washing device (1) as claimed in one of the previous claims, comprising the following steps: a) feeding said conveying (5) and/or gripping (6) devices of containers into said washing device (1) from the pre-washing area (3); b) spraying said conveying (5) and/or gripping (6) devices with a pre-washing liquid in said pre-washing area (3); c) feeding said conveying (5) and/or gripping (6) devices into the washing tank (7) containing a washing liquid, and immersing them until a predetermined level; d) emitting ultrasounds of predetermined intensity by ultrasound generators (14, 15) positioned on the walls and on the bottom of said washing tank (7); e) at the end of a predetermined period of time, feeding said conveying (5) and/or gripping (6) devices into a rinsing area (4) wherein they are rinsed with a rinsing liquid.

9. A method as claimed in claim 8 wherein said conveying (5) and/or gripping (6) devices pass through a drying area.

10. A method as claimed in claim 8 wherein said washing and/or pre-washing and/or rinsing fluids undergo filtering and/or regenerating and/or replacing operations at scheduled times.