Method of manufacturing a cooking utensil

• US 5,257,717 A
• Filed: 07/30/1992
• Issued: 11/02/1993
• Est. Priority Date: 07/30/1991
• Status: Expired due to Fees

• Current Assignee: AMC International ALFA Metalcraft Corporation AG
• Original Assignee: AMC International ALFA Metalcraft Corporation AG
• Inventors: Galle, Alfred
• Primary Examiner(s): Rosenbaum, Mark
• Assistant Examiner(s): Mah, Chuck Y.
• Application Number:
  US07/922,336
• Time in Patent Office: 460 Days
• Field of Search: 228/175, 228/184, 228/155, 228/265, 228/173.6, 228/263.16
• US Class Current: 228/173.6
• CPC Class Codes: A47J 27/002 Construction of cooking-vessels; Methods or processes of manufacturing specially adapted for cooking-vessels
• CPC Class Codes: A47J 36/02 Selection of specific materials, e.g. heavy bottoms with copper inlay or with insulating inlay

Abstract

A method of manufacturing a cooking utensil comprising a round container for the food. The container comprises a container, a plate made of heat-conducting material and a cap enclosing the plate, the cap being made from a sheet-metal disk and having a base provided with a convex curvature towards the container and also having collar which bears against the round container in a curved transition region between the container base and the container jacket. The container and the cap are made of stainless steel. The plate is intermetallically bonded to the container base and the cap. The plate, the sheet-metal disk and the container base are centered and connected by a central spot weld, using electric resistance welding. Next, the intermetallic bond is produced by single or multiple impulse pressure and permanent deformation and the cap collar is formed on the sheet-metal disk and its rim is placed around the container. Use is made of a sheet-metal disk having an edge which, during the shaping of the cap collar, is permanently deformed and pressed against the container. The sheet-metal disk, the plate and the container base are centered by the resistance welding so as to be resistant to impulse pressure. The pulse pressure is exerted so as to produce the convex curvature in the cap bottom. During impulse pressure, the air is first expelled from the region between the sheet-metal disk and the cap collar in process of formation. During and after this process, a seal is produced in the form of permanent deformation with regard to the plastic deformation of the plate material.

Claims

1. A method of manufacturing a cooking utensil comprising the steps of:

(a) assembling a container comprising a bottom, a plate of heat-conducting material lying against said bottom and a cap enclosing the plate, the cap being made from a sheet-metal disk and having a base formed with a convex curvature towards the container and also having a collar which abuts a round portion of the container in a curved transition region between the container bottom and a wall of the container, the container and the cap being made of stainless steel,

(b) centering the plate, the sheet metal disk and the container bottom being centered and joining the center and assembled by electric resistance welding to produce a central spot weld resistant to pulse pressure, and

(c) forming an intermetallic bond between said plate, said container bottom and said cap by at least one shot of pulse pressure and plastic deformation and forming a cap collar on the sheet-metal disk with a rim pressed against the container, said cap being formed from a sheet-metal disk and having an edge, said step of forming the intermetallic bond including the steps of;

(c₁) applying the pulse pressure so as to give a convex curvature to the base of the cap,

(c₂) simultaneously with step (c₁) driving the air out of a region between the disk and the cap,

(c₃) simultaneously with step (c₂) forming a recess in said container by pressing the edge thereagainst, said recess being formed with respective surfaces formed complementary to said edge upon contact therebetween the edge and the container,

(c₄) permanently pressing said edge against said recess, thereby producing a seal upon permanent deformation during plastic deformation of the plate material, and

(c₅) forming a collar on the plate material and pressing the collar into a region of the seal.

2. The method according to claim 1 wherein said plate has a thickness which, before plastic deformation in the cold state, is not more than 16% greater than after plastic deformation.

3. The method according to claim 1 wherein said sheet-metal disk has a diameter greater than a nominal outside diameter of the container.

4. The method according to claim 1 wherein said sheet-metal disk has a thickness about equal in thickness to sheet metal forming the container.

5. The method according to claim 1 wherein said sheet-metal disk is not more than 20% thinner than sheet metal forming the container.

6. The method according to claim 1 wherein the pulse pressure is exerted on the container, the cap and the plate at a temperature near the melting-point of the plate, and the pulse pressure tools are used at a temperature in the range from 100°

to 350°

C.

7. A method of making a cooking utensil which comprises the steps of:

forming a pot having a substantially flat bottom, a rounded transition region surrounding said bottom and a substantially cylindrical wall adjacent said transition;

applying to said bottom a circular plate having a diameter substantially equal to a diameter of said bottom and so that said plate does not project beyond said bottom over said transition region;

providing on said plate, a sheet-metal disk of a diameter greater than said plate so that a rim of said disk projects beyond said plate;

centering said disk and said plate on said bottom by spot welding said disk and said plate to said bottom substantially at centers of said disk, said plate and said bottom;

pressing said disk, said plate and said bottom between a pair of tools including an inner tool within said container bearing on said bottom and having a convex shape and an outer tool bearing on said disk and said plate and shaped to impart an outwardly concave curvature to said disk while bending said rim inwardly toward said transition region;

forming a recess in said transition region having a surface complementary to and abutting said rim brought in contact with said recess upon said pressing, providing thereby a seal between the inwardly bent rim and said transition region; and

applying at least one shot of pulse pressure of a magnitude and at a temperature so as to permanently, plastically deform said plate into said seal along said transition region while intermetallically bonding said disk to said plate and said plate to said container.