GB2232656A - Article handling apparatus and methods - Google Patents

Abstract

A method of lifting an article comprises the steps of freeze bonding to the article a device of low thermal mass and picking up and placing the article by lifting the device, especially in a food handling robot based cell having a gripper system which includes at least one gripper constituted by a cryogenic device in accordance with the invention. The device may be temporarily heated to form a film of liquid before it is frozen to the article.

Description

Title: Article handling apparatus and methods Field of invention This invention concerns article handling apparatus and methods.

Background to the invention Food preparation has traditionally been a labour intensive task. With increasing labour rates, and growing concerns over microbiological contamination that may be spread by humans handling foodstuffs, automatic preparation of foods is desirable. The meal assembly process is a key area for automation, providing cost effective handling techniques can be found for the range of foodstuffs involved.

Difficulties have been experienced in designing apparatus for handling sliced wet produce such as fruit, meats, vegetables and salad items for the purpose of arranging such items on a plate.

It is an object of the present invention to produce a novel apparatus and method which enables wet sliced items to be handled.

Summary of the invention According to the present invention a method of lifting an article comprises the step of freeze bonding a low thermal mass device onto the article and elevating the device with the article bonded thereto.

The technique works particularly well for wet or moist sliced items where moisture already exists on the surface of the article and therefore will exist at the interface with the device.

The system can however be readily adapted to handle dry products by introducing a film of water between the device and the article, for example by spraying.

Where the item to be picked is already frozen, eg frozen foods, the lifting device merely requires to have a low thermal mass which can be rapidly heated, eg by the passing of an electrical current through the device or through a heating element in association with this device.

Heating the device in contact with a frozen item will cause local melting to occur and release water. Removing the source of heat will cause the low thermal mass device to be cooled by conduction, and cause the water at the interface to refreeze, trapping the device and attaching it to the frozen item.

Where the item is not frozen, the lifting device may be formed from or include a thin-walled tube through which refrigerant can be ported. Gaseous or liquid refrigerants may be employed, eg: - supercooled air - liquid/gaseous nitrogen - Co2 - CFCIs - Ammonia - brine Insulating the tube from surrounding structure both thermally and electrically will enable an electric current to be passed, to heat up the tube and quickly release held items. An added advantage of this approach is the ability to raise the temperature of the device, between pick and place operations, to a level where microbiological sterilisation can occur.

In a preferred embodiment a lifting device incorporates a Peltier junction heat pump to rapidly chill or heat the face, of the device in contact with the article to be lifted by simply reversing the flow of electric current through the junction.

Heat of course must be dissipated from the Peltier junction and this can be achieved by a number of techniques such as, a water manifold, by air, C02 or N2 blast, or pumped low grade refrigerants.

Where short duration adhesion only is required, the device can be simplified to a passive device by incorporating an external chill facility into which the device is transferred to be chilled before performing a pick and place cycle. Very rapid chill times can be achieved if for example liquid nitrogen is used as the refrigerant in the external chill facility. Release can be effected using normal ambient heating or by electrical resistance heating or the like.

The invention has the following advantages: 1. Cell damage created by the freezing action on certain foodstuffs can be used for example to cause an imprint of a company logo on the foodstuff by employing a profiled device.

2. The device may be used in healthcare applications as a hand held or remote device to, for example: - transfer tissue samples, - transfer skin grafts, - manipulate organic items under sterile conditions.

3. The invention may be used in situations in which vacuum gripping could theoretically be employed, but where the application of vacuum is undesirable, eg where the item to be picked is porous, delicate or brittle.

4. The cryogenic lifting principle of the invention may be used with any solvent which can be frozen. It is not essential to use water.

5. Cold store component handling could be simplified by the use of a heated plate.

6. Fabrics, papers or films, traditionally difficult to handle, could be grasped using the invention.

7. Sterilisation of the plate may be effected by an appropriate level of heating, using the heating facility incorporated.

The invention also lies in apparatus for performing the above described methods and in a multi gripper facility of which one of the lifting devices is a cryogenic lifting device in accordance with the invention.

The invention may be incorporated in a robot based cell which can provide a flexible meal assembly facility for use in high throughput catering facilities such as: - in-flight kitchens - fast food chains - bulk catering units - pre-pack meal production lines The invention also lies in a method of handling articles comprising the steps of: (1) causing a coolant to flow through or around a lifting device to continuously cool at least a surface thereof, (2) moving the said surface into contact with an article to be lifted and causing the article to become freeze bonded to the surface, (3) moving the lifting device and article attached thereto into a desired location and (4) releasing the article by momentarily heating the surface without interrupting the flow of coolant, so that the surface can rapidly cool in its normal operating temperature ready to pick another article.

If necessary, the surface may be momentarily heated just before it is brought into contact with the article to be lifted so as to produce a flow of water over the said surface as it is brought into contact with the article to be lifted. The continuously flowing coolant rapidly refreezes the water film after the heating thereby causing the article to become freeze bonded to the said surface.

The invention also has an apparatus for performing the above method.

A possible configuration of such a system is outlined in Figure 1.

The robot based cell contains a series of feeder modules 10, 12, 14 arranged around the robot work envelope 16.

Feeder module types can include: - tray feeders for shingled sliced produce - stack feeders for stacked sliced meats or breads - bulk feeders for less fragile items, ie bread rolls, whole fruits, chocolates, nuts, etc., and these may include vision sorting systems to detect orientation and position.

- singulation systems supplying sorted items to a fixed pick position.

Running through the cell is a meal container feed line 18, 20 transferring trays of empty or partially prepared meal dishes from shelved trolleys at 18, through the robot access zone to re-stack on trolleys as completed meals, at 20.

The key to the system is the multi-gripper system carried by the robot 22. The multi-gripper 24 enables a number of different gripper types to be selected as required to handle the range of foodstuffs to be placed. Gripper types may include: vacuum, parallel action, air flow (vacuum hybrid), pivoting jaw or a cryogenic device as proposed by the present invention.

The selection of the required gripper is achieved by rotation of the gripper head 24. The robot performs a sequence of moves to assemble the meals from the appropriate foodstuffs, onto the tray(s) using the relevant gripper for each product type.

In accordance with the invention one of the grippers is a cryogenic device constructed as an embodiment of the invention, examples of which are given in Figures 2 and 3.

Thus in Figure 2a the gripper comprises a thin-walled tube 26 through which a refrigerant fluid (liquid or gas) can be pumped from a reservoir 28. The tube 26 is of electrical resistance material and is insulated from the mounting housing 30 by electrically insulating bushes 32, 34 to allow the tube to be heated due to the passage of an electric current.

Figure 2b is an underside plan view of the device shown in -Figure 2a.

Figure 3a illustrates an alternative arrangement using a Peltier junction heat pump for rapidly heating or cooling a face 36. Current is supplied to the Peltier junction device via conductive supports 38, 40.

Figure 3b shows the pick-up face 36 (in close proximity to the Peltier junction 42) and the chamber 44, to the rear, for absorbing and dissipating waste heat.

Figures 4a, 4b, 4c show a further arrangement in the form of a housing or main body 46 manufactured from a material which is electrically insulating and also a good thermal insulator, eg Tufnol (Trade Mark). The body 46 carries a pick-up face 48 formed of thin pressed stainless steel, and incorporates dual coolant chambers 50 through which a coolant, eg 99t ethanol, circulates (arrows 51) at between -20 C and -50 C.

Copper lobes 52 connect with the main body, and more especially the ends of the pick-up face 48, to enable passage of heating current through said face. The rectangular shape of the main body, and then of the pickup face, aids directionalisation of the current.

The arrangement enables the pick-up face to be heating rapidly, eg from chilled temperature to about +20C in not more than a quarter of a second, and return back down to chilled temperature in not more than 1 second after the heating current is stopped. Again, the electrical heating can also be utlised for sterilization purposes.

Claims (21)

Claims

1. A method of lifting an article comprising the steps of freeze bonding a low thermal mass device onto the article and elevating the device with the article bonded thereto.

2. A method according to claim 1, applied to moist or wet articles.

3. A method according to claim 1, applied to dry articles, including the step of introducing a film of water between the device and the article, for example by spraying.

4. A method according to claim 1, applied to frozen articles, including the step of temporarily applying heat to the surface of the article to create a film of moisture thereon.

5. A method according to claim 4, according to which heat is temporarily applied by a heating means forming part of the device.

6. A method according to claim 1 or claim 2 or clai 3, applied to unfrozen articles, according to which the lifting device includes a refrigerating means.

7. A method according to claim 6, according to which the lifting device is formed from or includes a thin-wailed tube through which refrigrant can be ported.

8. A method according to claim 7, employing a liquid or gaseous refrigerant such as: - supercooled air - liquid/gaseous nitrogen - Co2 - CFC's - Ammonia - brine

9. A method according to claim 7 or claim 8, accordi to which the tube is insulated from surroundir structure both thermally and electrically to enable an electric current to be passed, to heat up the tube and quickly release held articles.

10. A method according to claim 9, according to which the temperature of the device is raised, between pick and place operations, to a level where microbiological sterilisation occurs.

11. A method according to claim 9 or claim 1C, according to which the lifting device incorporates a Peltier junction heat pump to rapidly chill or heat the face of the device in contact with the article to be lifted by reversing the flow of electric current through the junction.

12. A method according to claim 11, according to which the device incorporates means for dissipating heat from the Peltier junction.

13. A method according to claim 6, including the step of chilling the device by an external chilling means into which the device is transferred before performing a pick and place cycle.

14. A method according to any preceding claim, wherein the face of the device to contact the article has a profiled logo thereon.

15. Apparatus for performing the method of any of claims 1 to 14 in a multi gripper facility of which one of the lifting devices is a cryogenic lifting device.

16. Apparatus according to claim 15, incorporated in a robot based cell which Provides a flexible meal assembly facility for use in high throughput catering facilities.

17. A method of handling articles comprising the steps of: (1) causing a coolant to flow through or around a lifting device to continuously cool at least a surface thereof, (2) moving t-he sa' surface into contact with an article to be lifted and causing the article to become freeze bonded to the surface, (3) moving the lifting dev ce and article attached thereto into a desired location, and (4) releasing the article by momentarily heating the surface without interrupting the flow of coolant, so that the surface can ran ly cool in its normal operating temperature ready to D' ck another article.

18. A method according to claim 17, wherein the said surface is momentarily heated just before it is brought into contact with the article to be lifted so as to produce a flow of water over the said surface as it is brought into contact with the article to be lifted, and the continuously flowing coolant rapidly refreezes the water film after the heating, thereby causing the article to become freeze bonded to the said surface.

19. Apparatus for carrying out the method of claim 17 or claim 18.

20. A method of handling an article substantially as hereinbefore described.

21. Apparatus for handling articles substantially as hereinbefore described with reference to the accompanying drawings.