GB2179239A

GB2179239A - Improvements in cooking vessels

Info

Publication number: GB2179239A
Application number: GB08619270A
Authority: GB
Inventors: Yanta H T Lam; Massey Umehara
Original assignee: Meyer Manufacturing Co Ltd
Current assignee: Meyer Manufacturing Co Ltd
Priority date: 1985-08-12
Filing date: 1986-08-07
Publication date: 1987-03-04
Also published as: GB8619270D0; GB8520198D0

Abstract

A cooking vessel is provided having aluminium side walls and an aluminium bottom to which an aluminium disk is applied, preferably by brazing to give a base having a minimum thickness of 2.5 mm. Optionally a stainless steel disk may be applied to the aluminium disk.

Description

SPECIFICATION Improvements in Cooking Vessels The present invention relates to improved cooking vessels.

The most satisfactory cooking vessels are those which have a thick base of at least 3.0 mm thickness since such cooking vessels conduct heat to the contents thereof more evenly than thinner based cooking vessels. Cooking vessels made of aluminium are generaliy manufactured by being stamped from a sheet of aluminium or cast. In the former case, the whole of the cooking vessel i.e. the base and the side walls are made from aluminium of the thickness required for the base which is wastefu I of aluminium since it is not necessaryforthe side walls of the cooking vessels to be as thick as the base and therefore this adds to the costs. In the latter case, the base of the cooking vessel can be made thicker than the side walls.

It is known to produce stainless steel cooking vessels to the bottom of which is brazed an aluminium disk which provides the cooking vessel with a thicker base, so providing better and more even heat conduction from the heating medium to the contents of the cooking vessel. Often this aluminium disk has a layer of stainless steel applied to it to prevent warping of the aluminium disk and damage due to knocks which can occur after a period of use, which then affects the even heat conduction properties of the cooking vessels.

However, cooking vessels made of stain less steel are expensive.

We have sought to provide a cooking vessel made primarily of aluminium which has excellent heat conduction properties.

Accordingly, the present invention provides a cooking vessel comprising aluminium side walls and an aluminium bottom stamped from a sheet of aluminium, to the bottom of which is applied an aluminium diskto provide the cooking vessel with a base preferably having a minimum thickness of 2.5 mm. The aluminium disk is preferably applied to the cooking vessel by brazing.

Preferably the aluminium disk has a disk of stainless steel applied to it. This serves to protect the aluminium base from damage due to knocks and to permit the cooking vessel to be used on induction cookers which, to function, require the cooking vessel used thereon to have magnetic properties.

When the cooking vessel is to be used specifically on an induction cooker, the stainless steel disk used must have a minimum iron content of 82%. For example, 430 stainless steel can be used.

Additionally aluminium is known to mark cookers and kitchen counter tops and the use of a stainless steel disk wili eliminate this problem. Grease stains are notariously difficult to remove from untreated aluminium and the use of a stainless steel disk will prevent grease accumulating and turning unsightly.

Since the cooking vessel of the present invention is manufactured primarily from aluminium, it is possible to coat both the inside and outside thereof with polytetrafluoroethylene to provide both the inside and outside with a hard durable finish and, so far as the interior is concerned, a "non-stick" finish.

Preferably the stainless steel layer is etched, both to provide an attrawfve finish and to ensure that at least part of the stainless steel layer is matt which is essential if the cooking vessel is to be used on ceramic hobs where the use of a cooking vessel with a too shiny base can cause the ceramic hob to switch itself off.

The present invention also provides a method of manufacturing a cooking vessel which comprises stamping a circle from an aluminium sheet, preferably of 2.0 mm thickness, forming the circle into the required cooking vessel shape and applying an aluminium disk to the bottom of the cooking vessel to give a base preferably having a thickness of 2.5 cm and, optionally, applying a disk of stainless steel preferably of a minimum thickness of 0.5 mm to the aluminium disk.

In a preferred embodiment the aluminium disk has a thickness of from 3.5 mm to 4.5 mm.

To achieve better adhesion of the aluminium disk to the base of the cooking vessel, the cooking vessel is degreased in a hot water/detergent bath or in an alkaline bath prior to the brazing whereby the aluminium disk and the stainless steel disk are applied to the cooking vessel.

Brazing is preferably achieved by high frequency induction heating using a flux and brazing powder.

After the brazing step, the aluminium of both the inside and the outside of the cooking vessel may be given a coating of polytetrafluoroethylene, if desired, and then the cooking vessel is trimmed and polished.

After the trimming and polishing steps, a design can be applied to the stainless steel base. Firstly, the design is transferred to the stainless steel by screen printing and then to those portions of the stainless steel disk to remain shiny, is applied a masking paste comprising a plastic resin and organic vehicle.

The stainless steel base is then passed into an etching solution which preferably contains chlorine ions e.g. iron chloride, rinsed and the masking paste removed.

In a modification of the present invention, there is provided a cooking vessel manufactured of any suitable material, to the base of which is applied a disk of stainless steel. The disk of stainless steel having a design applied thereto by screen printing and etching to provide a base with an attractive design and with matt and shiny portions.

1. A cooking vessel comprising aluminium side walls and an aluminium bottom stamped from a sheet of aluminium, an aluminium disk applied to the bottom of the cooking vessel to provide a base having a thickness of 2.5 mm.

2. A cooking vessel as claimed in Claim 1, in which the aluminium disk has a thickness of from 3.5 mm to 4.5 mm.

3. A cooking vessel as claimed in Claim 1 or 2, in which the aluminium disk is applied to the bottom of the cooking vessel by brazing.

4. A cooking vessel as claimed in any of Claims 1

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in Cooking Vessels The present invention relates to improved cooking vessels. The most satisfactory cooking vessels are those which have a thick base of at least 3.0 mm thickness since such cooking vessels conduct heat to the contents thereof more evenly than thinner based cooking vessels. Cooking vessels made of aluminium are generaliy manufactured by being stamped from a sheet of aluminium or cast. In the former case, the whole of the cooking vessel i.e. the base and the side walls are made from aluminium of the thickness required for the base which is wastefu I of aluminium since it is not necessaryforthe side walls of the cooking vessels to be as thick as the base and therefore this adds to the costs. In the latter case, the base of the cooking vessel can be made thicker than the side walls. It is known to produce stainless steel cooking vessels to the bottom of which is brazed an aluminium disk which provides the cooking vessel with a thicker base, so providing better and more even heat conduction from the heating medium to the contents of the cooking vessel. Often this aluminium disk has a layer of stainless steel applied to it to prevent warping of the aluminium disk and damage due to knocks which can occur after a period of use, which then affects the even heat conduction properties of the cooking vessels. However, cooking vessels made of stain less steel are expensive. We have sought to provide a cooking vessel made primarily of aluminium which has excellent heat conduction properties. Accordingly, the present invention provides a cooking vessel comprising aluminium side walls and an aluminium bottom stamped from a sheet of aluminium, to the bottom of which is applied an aluminium diskto provide the cooking vessel with a base preferably having a minimum thickness of 2.5 mm. The aluminium disk is preferably applied to the cooking vessel by brazing. Preferably the aluminium disk has a disk of stainless steel applied to it. This serves to protect the aluminium base from damage due to knocks and to permit the cooking vessel to be used on induction cookers which, to function, require the cooking vessel used thereon to have magnetic properties. When the cooking vessel is to be used specifically on an induction cooker, the stainless steel disk used must have a minimum iron content of 82%. For example, 430 stainless steel can be used. Additionally aluminium is known to mark cookers and kitchen counter tops and the use of a stainless steel disk wili eliminate this problem. Grease stains are notariously difficult to remove from untreated aluminium and the use of a stainless steel disk will prevent grease accumulating and turning unsightly. Since the cooking vessel of the present invention is manufactured primarily from aluminium, it is possible to coat both the inside and outside thereof with polytetrafluoroethylene to provide both the inside and outside with a hard durable finish and, so far as the interior is concerned, a "non-stick" finish. Preferably the stainless steel layer is etched, both to provide an attrawfve finish and to ensure that at least part of the stainless steel layer is matt which is essential if the cooking vessel is to be used on ceramic hobs where the use of a cooking vessel with a too shiny base can cause the ceramic hob to switch itself off. The present invention also provides a method of manufacturing a cooking vessel which comprises stamping a circle from an aluminium sheet, preferably of 2.0 mm thickness, forming the circle into the required cooking vessel shape and applying an aluminium disk to the bottom of the cooking vessel to give a base preferably having a thickness of 2.5 cm and, optionally, applying a disk of stainless steel preferably of a minimum thickness of 0.5 mm to the aluminium disk. In a preferred embodiment the aluminium disk has a thickness of from 3.5 mm to 4.5 mm. To achieve better adhesion of the aluminium disk to the base of the cooking vessel, the cooking vessel is degreased in a hot water/detergent bath or in an alkaline bath prior to the brazing whereby the aluminium disk and the stainless steel disk are applied to the cooking vessel. Brazing is preferably achieved by high frequency induction heating using a flux and brazing powder. After the brazing step, the aluminium of both the inside and the outside of the cooking vessel may be given a coating of polytetrafluoroethylene, if desired, and then the cooking vessel is trimmed and polished. After the trimming and polishing steps, a design can be applied to the stainless steel base. Firstly, the design is transferred to the stainless steel by screen printing and then to those portions of the stainless steel disk to remain shiny, is applied a masking paste comprising a plastic resin and organic vehicle. The stainless steel base is then passed into an etching solution which preferably contains chlorine ions e.g. iron chloride, rinsed and the masking paste removed. In a modification of the present invention, there is provided a cooking vessel manufactured of any suitable material, to the base of which is applied a disk of stainless steel. The disk of stainless steel having a design applied thereto by screen printing and etching to provide a base with an attractive design and with matt and shiny portions. CLAIMS

4. A cooking vessel as claimed in any of Claims 1 to 3, in which a disk of stainless steel is applied to the aluminium disk.

5. A cooking vessel as claimed in Claim 4, in which the stainless steel disk has a thickness of at least 0.5 mm.

6. A cooking vessel as claimed in any of Claims 1 to 5, in which the inside and outside aluminium surfaces are coated with polytetrafluoroethylene.

7. A cooking vessel as claimed in any of Claims 4 to 6, in which the stainless steel disk is etched.

8. A method of manufacturing a cooking vessel which comprises stamping a circle from a sheet of aluminium, forming the circle into the required cooking vessel shape and applying an aluminium disk to the bottom of the cooking vessel to provide a base with a thickness of 2.5 cm.

9. A method as claimed in Claim 8, in which the aluminium sheet has a thickness of 2.0 mm.

10. A method as claimed in Claim 8 or 9, in which the aluminium disk has a thickness from 3.5 mm to 4.5 mm.

11.A method as claimed in any of Claims 8to 10, in which a disk of stainless steel is applied to the aluminium disk.

12. A method as claimed in Claim 11 in which the stainless steel disk has a thickness of at least 0.5 mm.

13. A method as claimed in Claim 11 or 12 in which a design is applied to the stainless steel disk by screen printing, portions of the design are covered by a masking paste, the stainless steel base is etched and the masking paste removed.

14. A method as claimed in any of claims 8 to 13, in which the cooking vessel is degreased prior to applying the aluminium disk, with or without the stainless steel disk, to the bottom of the cooking vessel.

15. A method as claimed in Claim 14, in which the degreasing is by means of a hot water bath, a detergent bath or an alkaline bath.

16. A method as claimed in any of Claims 8 to 15, in which the aluminium disk, with or without the stainless steel disk, is applied to the bottom of the cooking vessel by brazing.

17. A method as claimed in Claim 16, in which the brazing is by high frequency induction heating using a flux and brazing powder.

18. A cooking vessel having a disk of stainless steel applied thereto with the stainless steel disk having a design applied thereto by screen printing and etching.