U.S. patent application number 10/552098 was filed with the patent office on 2006-09-07 for method for producing cookware, in particular a pot, pan or similar and cookware produced according to said method.
This patent application is currently assigned to ZWILLING J. A. Hanckels AG. Invention is credited to Joachim Droese.
Application Number | 20060196877 10/552098 |
Document ID | / |
Family ID | 34202096 |
Filed Date | 2006-09-07 |
United States Patent
Application |
20060196877 |
Kind Code |
A1 |
Droese; Joachim |
September 7, 2006 |
Method for producing cookware, in particular a pot, pan or similar
and cookware produced according to said method
Abstract
The invention relates to a method for producing cookware (1)
consisting of a base body (5) that is attached to a base (2), in
particular a pot, pan or similar. In a first step of said method,
the base body (5) is produced in one-piece, preferably in a
deep-drawing process and in a second step, the base body (5) is
connected to the preferably multi-part base (2), which is composed
of an inlay (6) and a shell (7) that encapsulates said inlay (6).
The aim of the invention is to provide a simple and cost-effective
method for producing cookware (1) comprising a base (2) that only
deforms within narrow tolerance limits, even when subjected to
comparatively high thermal stress. To achieve this, the base (2) is
calibrated by means of a displacement-controlled press, preferably
a toggle press.
Inventors: |
Droese; Joachim;
(Langenfeld, DE) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
ZWILLING J. A. Hanckels AG
Solingen
DE
|
Family ID: |
34202096 |
Appl. No.: |
10/552098 |
Filed: |
August 14, 2004 |
PCT Filed: |
August 14, 2004 |
PCT NO: |
PCT/EP04/09135 |
371 Date: |
October 4, 2005 |
Current U.S.
Class: |
220/573.3 ;
220/23.87 |
Current CPC
Class: |
A47J 27/022 20130101;
A47J 36/02 20130101; A47J 27/002 20130101; B21D 51/22 20130101 |
Class at
Publication: |
220/573.3 ;
220/023.87 |
International
Class: |
B65D 21/02 20060101
B65D021/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 27, 2003 |
DE |
103 39 426.5 |
Claims
1. A method for producing cookware composed of a base body and a
bottom attached thereto, in particular a pot, a pan or the like, in
which in a first step of said method, the base body is formed as
one integral piece, preferably by means of deep-drawing, and in a
second step of said method, the base body is connected to the
preferably multi-part bottom, which comprises an inlay as well as a
capsule, which receives said inlay, characterized in that the
bottom is calibrated by means of a pressing device having a
position control, preferably a toggle press.
2. A method according to claim 1, characterized in that the bottom
is mechanically reinforced.
3. A method according to claim 2, characterized in that reinforcing
ribs are stamped into the lower side of the bottom.
4. A method according to claim 3, characterized in that the
stamping of the reinforcing ribs is carried out in a position
controlled manner.
5. A method according to claim 1, characterized in that a
calibration of the bottom is carried out with simultaneous
formation of the reinforcing ribs.
6. A method according to claim 1, characterized in that the base
body and the bottom are welded or soldered to each other.
7. A method according to claim 1, characterized in that the
connection of base body and bottom, on the one hand, and the
calibration of the bottom, on the other hand, are carried out in
one step of said method.
8. A device for carrying out the method according to claim 1,
characterized by a pressing device having a position control,
preferably in form of a toggle press.
9. A device according to claim 8, characterized by concave force
plugs.
10. A device according to claim 8, characterized by a cookware
receiving portion, which can be moved relatively to the pressing
device.
11. Cookware, in particular a pot, pan or the like, composed of a
preferably cylindric base body and a bottom attached to the base
body, characterized in that the bottom is convex, i.e. bulged
inwards with respect to the lower side thereof, such that the
deformation of the bottom, which is caused by a thermal stress, has
a value of <0.7%, preferably <0.35% of the bottom diameter,
for which purpose the bottom is calibrated in a position controlled
manner.
12. Cookware according to claim 11, characterized in that the
bottom is mechanically reinforced.
13. Cookware according to claim 12, characterized in that the
bottom comprises reinforcing ribs.
14. Cookware according to claim 13, characterized in that the
reinforcing ribs are grooves, which are formed in the lower side of
the bottom, and the arrangement of which preferably forms a uniform
pattern.
15. Cookware according to claim 14, characterized in that the
pattern formed by the reinforcing ribs has a rotation or mirror
symmetric structure.
16. Cookware according to claim 11, characterized in that the base
body is formed by a side wall, which encloses a volume, and which
comprises a first end area and a second end area opposing the first
one, wherein the first end area is open and can be closed by a
cover and the second end area is closed.
17. Cookware according to claim 11, characterized in that the base
body is formed as one integral piece.
18. Cookware according to 17 claim 11, characterized in that the
bottom is a multi-part piece and comprises an inlay as well as a
capsule, which receives said inlay.
19. Cookware according to claim 11, characterized in that the base
body and the bottom are soldered or welded to each other.
20. Cookware according to claim 11 characterized in that the base
body is made of a rust-proof material, preferably stainless
steel.
21. Cookware according to claim 11, characterized in that the inlay
is made of a thermoconducting material, preferably aluminum or
magnesium.
22. Cookware according to claim 11 characterized in that the
capsule is made of a magnetizable material, preferably a ferritic
stainless steel.
Description
[0001] The invention relates to a method for producing cookware
composed of a base body and a bottom attached thereto, in
particular a pot, a pan or the like, in which in a first step of
said method, the base body is formed as one integral piece,
preferably by means of deep-drawing, and in a second step of said
method, the base body is connected to the preferably multi-part
bottom, which comprises an inlay as well as a capsule, which
receives said inlay.
[0002] Pots, pans or similar cookware are principally known in the
state of the art and have proved a success in daily practical use.
However, modern cookware has to meet higher and higher quality
requirements, so that there is still a need of innovations.
[0003] Thus, modern cookware does not only have to meet the
requirement to assure an impeccable preservation and heating of
food, but it also has to meet high requirements with respect to
aesthetics, which in particular influences the selection of usable
materials. Furthermore, in modern kitchens, very different forms of
stoves for heating food are used, which respectively require
different qualities of cookware material. Usual cooker forms are
for example gas cookers, electric cookers and induction cookers.
Herein, the induction cooker, in comparison to gas cookers or
electric cookers, has the particularity that no heat transfer
between the cooker on the one hand and the cookware on the other
hand takes place, since the cookware is directly heated by building
up an induction field. However, the use of an induction cooker
requires that at least the bottom of the cookware used in
combination with the induction cooker is made of inductive
material.
[0004] In order to meet the different requirements of the material
used for cookware, it is known in the state of the art to use
material combinations, wherein it has in particular become common
to use different materials for the base body of the cookware, on
the one hand, and the bottom of the cookware, which is attached to
the base body, on the other hand. It is also known to form the
bottom of the cookware as a so called sandwich bottom and to
provide different material layers depending on the desired material
properties. However, when the cookware is properly heated, it has
proved to be disadvantageous that the use of different materials
leads to a delay, in particular in the area of the bottom of the
cookware. This is caused by the different coefficients of thermal
expansion of the respectively used materials, such that the heating
leads to material dependent differences of expansion, which result
in the consequence that certain areas of the cookware expand or
shrink differently under heat influence. This effect proves
extremely disadvantageous for the so called sandwich bottoms, since
due to the different material expansions, it cannot be assured,
within the entire temperature range, that the cookware completely
leans on the surface of the cooking area of the cooker. On the
contrary, a deformation of the bottom is caused during the heating
of the cookware, which leads to the fact that the entire surface of
the bottom is not in contact with the cooking area of the cooker,
but only certain areas of the bottom. The contact area between the
cooking area of the cooker and the bottom of the cookware, which
depends on the ruling temperature, makes the obtained heat transfer
between cooker and cookware vary in a disadvantageous way, so that
it is not possible to precisely regulate the heat quantity that
shall be transferred to the cookware. Furthermore, the thermally
caused barrelling of the bottom, which causes the cookware bottom
to rest on the cooking area of the cooker only in certain areas,
can provoke tilting motions of the cookware with respect to the
cooking area. This is not only a drawback with respect to security
aspects, but the user of the cookware will perceive the smallest
thermal deformation of the cookware bottom, which will make him
doubt of the quality of the cookware used by him. A thermally
caused concave bulging of the bottom is equally disadvantageous,
since in this case, an air buffer, which acts as isolator, is
formed between the cookware bottom on the one hand and the cooking
area of the cooker on the other hand, whereby the desired heating
of the cookware is adversely affected.
[0005] The previously described drawbacks have an even stronger
effect, if the cookware shall also be used in combination with an
induction cooker. In this case, the bottom of the cookware has
namely to be at least partially made of an inductive material,
which increases the variety of the materials combined with each
other.
[0006] On the base of the above mentioned facts, it is the object
of the invention to provide a method for producing cookware, which
simultaneously enables a simple and economic realization and the
production of cookware, which comprises a bottom that only deforms
within narrow tolerance limits, even when subjected to
comparatively high thermal stress. The invention shall also propose
a cookware.
[0007] This a I m is achieved by the invention in that it proposes
a method for producing cookware composed of a base body and a
bottom attached thereto, in particular a pot, a pan or the like, in
which in a first step of said method, the base body is formed as
one integral piece, preferably by means of deep-drawing, and in a
second step of said method, the base body is connected to the
preferably multi-part bottom, which comprises an inlay as well as a
capsule, which receives said inlay, characterized in that the
bottom is calibrated by means of a pressing device having a
position control, preferably a toggle press.
[0008] The particularity of the method according to the invention
is the calibration of the bottom by means of a pressing device
having a position control. Hereby, it is advantageously achieved
that, independent from the force to be used, the bottom is always
identically formed. This enables reproducibility within the
narrowest range of tolerance, since in contrast to a
force-controlled pressing operation, the desired forming of the
bottom is always obtained, which is in particular advantageous, if
the bottom of the cookware, which is composed of different material
components, consists of several parts. Consequently, the
application of the method according to the invention leads to the
production of a cookware bottom, which only presents a small
deformation, even if subjected to a comparatively high thermal
stress, which deformation has a value of .ltoreq.0.7%, preferably
.ltoreq.0.35% of the bottom diameter. Thus, if the cookware
produced according to said method is used according to the intended
purpose, the bottom is neither affected by an undesirable bulging
inwards nor by an undesirable bulging outwards. This helps to
advantageously avoid both the danger of a tilting slope resulting
form the barrelling of the bottom and the danger of an air buffer
isolation, which is formed as a result of the convex bulging of the
bottom, including the tendency to burned edges. To the contrary,
due to the calibration carried out according to the invention, a
forming of the cookware bottom is achieved, which provides for the
substantially planar rest of the cookware bottom on the cooking
area of the cooker, if used within the usual temperature range,
whereby an optimized heating of the cookware can be achieved.
[0009] According to another proposal of the invention, it is
intended to form a mechanically reinforced bottom. Complementary to
the forming of the cookware bottom obtained by means of the
calibration, this measure leads to an additional form stability,
which advantageously causes the bottom to remain free of
deformation nearly within the entire temperature range, which
assures a planar rest of the cookware bottom on the cooking area of
the cooker, even at different temperatures. This increases the
stability of the cookware on the one hand, and on the other hand,
tilting motions of the cookware, which are perceived by the
customer as in particular a defect as to quality, are efficiently
prevented. According to a special proposal of the invention, it is
intended to press reinforcing ribs into the lower side of the
cookware bottom. The reinforcing ribs are preferably ribs which are
vaulted towards the base body and which are stamped into the lower
side of the cookware bottom by using a corresponding die or a
corresponding stamping device. Herein, according to the preferably
used stamp pattern, a correspondingly formed die or a
correspondingly formed stamping device can be used, such that the
ribs, which are intended to reinforce the cookware bottom, can be
formed in only one stamping step.
[0010] In order to assure the reproducibility of the method
according to the invention, another aspect of the invention
proposes to carry out the forming of the reinforcing ribs in a
position controlled manner. Hereby, it is advantageously achieved
that, independent from the force to be applied, the forming of the
reinforcing ribs is always the same. Hereby, it is achieved that,
independent from eventual tolerances of the thickness of the
cookware bottom, i.e. of the inlay or the capsule, always equal
reinforcing ribs are formed, such that cookware produced according
to the method of the invention always meets the same quality
requirements. A force controlled forming of the reinforcing ribs
would not be able to assure a reproducibility in this sense, since
dependent on geometric tolerances, which inevitably arise in the
course of carrying out the method, cookware dependent press forces
have to be applied for forming the reinforcing ribs, such that with
a force controlled method, there would be quality differences in
the forming of the reinforcing ribs. In order to avoid this
disadvantage and to assure the reproducibility of the cookware
produced according to the method of the invention, it is intended
according to the invention to carry out the forming of the
reinforcing ribs in a position controlled manner.
[0011] According to another aspect of the invention, the
reinforcing ribs are stamped into the cookware bottom with
simultaneous calibration. By calibration one has to understand a
deformation of the cookware bottom, according to which, at room
temperature, the bottom has a slightly inwards bulged, i.e. convex
form with respect to the lower side of the bottom. At a higher
temperature, that acts upon the cookware bottom, this one will
expand against the convex bulging provided at room temperature
while supporting the reinforcing ribs, such that the cookware
bottom will rest in a planar manner on the cooking area of the
cooker within the temperature range that is interesting for the
proper use of the cookware.
[0012] According to another aspect of the invention, the base body
and the bottom are welded or soldered to each other. With respect
to welding, the so called press welding is an advantageous option.
Herein, the parts to be connected to each other are pressed onto
each other with high pressure and simultaneously interconnected in
an adhesive bond by supplying corresponding energy. According to an
alternative realization of the method, the base body and the bottom
can be connected to each other by means of soldering, wherein
according to this realization of the method, the components to be
connected to each other are heated in a furnace with preceding
spreading of a solder that can be spread. For connecting the bottom
and the base body by means of press welding, it is intended
according to a special aspect of the invention to carry out the
connection of base body and bottom as well as the calibration and
optionally also the forming of the reinforcing ribs in one process
step. This measure enables an in particular cost efficient and over
all quick carrying out of the method, since it is only required to
provide the base body as first component and the bottom as second
component and then to connect them to each other in only one
working step in order to form the finished cookware. If necessary,
further process steps for cleaning, polishing or other treatment of
the cookware can follow after finishing the cookware according to
the invention. However, it is decisive, that the cookware according
to the invention can be finished in only one process step.
[0013] For carrying out the method according to the invention, the
invention further proposes a device, which is characterized by a
pressing device having a position control. Hereby, the above
described reproducibility of the calibration and the reinforcing
ribs, which shall be formed into the cookware bottom, is achieved.
As pressing device, a toggle press is preferably used, which works
like a four-bar chain and is moved from an upper dead centre into a
lower dead centre during the pressing operation. The distance,
which is thus covered by the compression moulding die, is always
the same, such that independent from eventual geometric tolerances
of the cookware to be produced, the forming of the reinforcing ribs
is always the same.
[0014] According to another aspect of the invention it is intended
that the device comprises concave force plugs. Hereby, a
calibration of the cookware bottom is achieved, which results in an
inwards bulged, i.e. convex form with respect to the lower side of
the bottom, which leads to the above described advantages.
Furthermore, it is possible that the force plug located on the side
of the bottom of the cookware comprises a so called pattern in form
of a positive stamp of the pattern of the reinforcing ribs, which
shall be stamped into the bottom of the cookware. The bottom of the
cookware can thus be calibrated and provided with the reinforcing
ribs according to the invention in only one pressing operation.
[0015] According to another aspect of the invention it is intended
that the pressing device comprises a pot receiving portion, which
can be moved relatively to the first one. This kind of design
advantageously allows a simplified carrying out of the method,
since due to the movable cookware receiving portion, the pressing
device can be filled or finished cookware can be removed from the
pressing device in a comfortable way for the operator.
[0016] For the solution of the above mentioned task, it is
proposed, with respect to the cookware, to form cookware, in
particular a pot, pan or the like, which is composed of a
preferably cylindric base body and a bottom attached to the base
body, characterized in that the bottom is convex, i.e. bulged
inwards with respect to the lower side thereof, such that the
deformation of the bottom, which is caused by a thermal stress, has
a value of .ltoreq.0.7%, preferably .ltoreq.0.35% of the bottom
diameter, for which purpose the bottom is calibrated in a position
controlled manner.
[0017] This design of the cookware bottom according to the
invention allows the bottom to be nearly completely exempt from
deformation, even if subjected to a comparatively high thermal
stress, so that convex or concave bulging of the cookware bottom
has a comparatively small value with respect to the bottom
diameter. Herein, the deformation of the bottom resulting from a
thermal stress is .ltoreq.0.7%, preferably .ltoreq.0.5%, preferably
.ltoreq.0.35% with respect to the bottom diameter.
[0018] In spite of the eventual use of very different materials,
the design of the cookware bottom according to the invention is
able to substantially resist a deformation caused by thermal
stress. In contrast to cookware known in the state of the art, the
calibration of the bottom, which is carried out in a position
controlled manner, permits to obtain a forming, which acts against
the thermal tensions generated due to the different coefficients of
expansion of the different materials during a heating of the
cookware and thus minimizes them, so that the forces are
equilibrated inside the cookware bottom. Hereby, a deformation of
the cookware bottom can be essentially avoided.
[0019] According to a special aspect of the invention, the cookware
bottom is mechanically reinforced. This leads to the formation of
mechanical barriers, which additionally increase the mechanical
flexural resistance of the cookware. In a design of the bottom
according to the invention, also materials having very different
coefficients of thermal expansion can be combined with each other
without provoking a deformation of the cookware bottom, since the
mechanical barriers act against the different material expansions,
which are generated due to a thermal stress, and the inner forces
related thereto, which supports the forming of the bottom produced
by the calibration.
[0020] According to a further aspect of the invention, the bottom
comprises reinforcing ribs. These ones are preferably grooves,
which are formed in the cookware bottom and positioned, such that
they increase the mechanical flexural resistance of the entire
cookware bottom. The grooves can be integrated by means of a
pressing operation, in which the grooves are stamped into the
cookware bottom using corresponding dies. By the term reinforcing
ribs one has to understand any forms of impression, which act in
the previously described sense as mechanical barriers and act
against a deformation of the cookware bottom caused by thermal
tensions.
[0021] The grooves formed in the cookware bottom are preferably
arranged in a uniform pattern. Hereby, a compensation of forces is
advantageously achieved, which equally acts over the entire
cookware bottom, such that also with thermal tensions, which only
occur in certain areas, which is for example the case if the
cookware is only partially in contact with the heated cooking area
of the cooker, a thermally caused deformation of the cookware
bottom is prevented. The arrangement of the reinforcing ribs in
form of a uniform pattern can be for example achieved according to
a characteristic of the invention, in that the pattern has a
rotation or mirror symmetry. Other arrangement forms of the
reinforcing ribs are of course possible, since in the sense of the
invention it is only important that the arrangement of the
reinforcing ribs additionally increases the mechanical flexural
resistance of the cookware bottom, such that this one resists its
own tensions caused by thermal stress essentially without any
deformation.
[0022] According to another aspect of the invention it is intended,
that the base body is formed by a side wall, which encloses a
volume, and which comprises a first end area and a second end area
opposing the first one, wherein the first end area is open and can
be closed by a cover and the second end area is closed. Herein, the
base body is preferably produced as one integral piece and is for
example made of a rust-proof material, such as e.g. stainless
steel. This kind of design of the base body advantageously enables
to select the base body material with respect to the material
properties thereof, such that it is particularly suitable for the
later contact with the food to be heated in the cookware. Herein,
stainless steel is in particular suitable, because this one is easy
to clean and also material resistant against possibly aggressive
foodstuffs. Furthermore, it also resists mechanical pressure and/or
impact stresses, such as they can for example occur during a proper
use by using kitchen utensils, such as for example wooden spoons or
the like.
[0023] According to another aspect of the invention, the bottom is
a multi-part piece and comprises an inlay as well as a capsule,
which receives said inlay. Such a material combination used for the
cookware bottom helps to obtain a design which meets several
requirements. The capsule, which receives said inlay, can thus be
made of e.g. a magnetizable material, preferably a ferritic
stainless steel, so that the cookware according to the invention is
also suitable for the use in combination with an induction cooker.
The inlay received by the capsule is preferably made of a highly
thermoconducting material, such as e.g. aluminium or magnesium.
Hereby, an improved heat transfer is achieved, such that altogether
a quicker heating of the foodstuffs in the cookware with less heat
loss can be achieved.
[0024] According to another aspect of the invention, it is intended
that the base body and the bottom are soldered or welded to each
other. A permanent connection, which also resists mechanical
influences, between base body on the one hand and bottom on the
other hand is thus assured. A good heat transferability between
bottom and base body is also assured.
[0025] Other advantages and characteristics of the invention will
appear from the following description made with respect to the
figures. Herein:
[0026] FIG. 1: is a schematic sectional view of an embodiment of
the cookware according to the invention in form of a pot;
[0027] FIG. 2: is a schematic view from below of the cookware
according to the invention from FIG. 1 and
[0028] FIG. 3: is a partially sectional side view of the cookware
according to the invention during the pressing operation.
[0029] FIG. 1 is a partially sectional side view, which represents
the cookware according to the invention in form of a pot 1. Pot 1
is composed of a base body 5 and a bottom 2, which are preferably
welded to each other.
[0030] Said base body 5 is formed by a side wall, which encloses a
volume and which comprises a first end area 3 and a second end area
4 opposing the first one, wherein the first end area 3 is open and
can be closed by a cover. The second end area 4 is closed and is
adjacent to bottom 2. Base body 5 is preferably made of a
rust-proof material, for example stainless steel.
[0031] Concerning bottom 2, it is a multi-part piece and comprises
an inlay 6 as well as a capsule 7, which receives said inlay 6.
Inlay 6 is preferably made of a thermoconducting material, such as
e.g. aluminium. In contrast to this, capsule 7, which receives said
inlay 6, is made of a preferably magnetizable material, for example
a ferritic stainless steel, such that pot 1 according to the
invention can also be used in combination with an induction
cooker.
[0032] FIG. 2 shows pot 1 according to FIG. 1 in a view from below.
One can see that the side of bottom 2, which is opposing base body
5, is provided with reinforcing ribs 8, which have the form of
grooves stamped into the bottom. Due to the formation of the
reinforcing ribs 8, a mechanical reinforcement of bottom 2 is
achieved, which acts as mechanical barrier and results in an
increased flexural resistance of bottom 2. The thermal tensions,
which are caused by the different coefficients of thermal expansion
of the used materials during a heating of pot 1, can thus be
compensated, such that bottom 2 nearly remains exempt of
deformation, even if subjected to high thermal stresses of pot 1.
This is not only an advantage with respect to security aspects, but
tilting motions can also be prevented, which would otherwise occur
with a bottom, that is not exempt of deformation. Hereby, a uniform
heating of the cookware bottom with a simultaneous shortening of
the heating up period required for a desired heating is
achieved.
[0033] FIG. 3 is a schematic representation, which shows the
arrangement of pot 1 according to the invention in a pressing
device, which is no further represented in details, and which
comprises the two force plugs 9 and 10. When the method is carried
out, the upper force plug 10 is moved downwards in the direction of
force plug 9 in a position controlled manner. Pot 1, which is
situated between the two force plugs, is hereby compressed in the
area of bottom 2 of pot 1, which results in a calibration of the
bottom and in the complementary stamping of the reinforcing ribs 8
represented in FIG. 2 into the lower side of bottom 2. For the
purpose of calibration, the two force plugs 9 and 10 are preferably
concave on the side of the pot, such that the finished pot bottom
has an inwards bulged, i.e. convex form.
LIST OF REFERENCE NUMERALS
[0034] 1 pot [0035] 2 bottom [0036] 3 open end area [0037] 4 closed
end area [0038] 5 base body [0039] 6 inlay [0040] 7 capsule [0041]
8 reinforcing rib [0042] 9 force plug [0043] 10 force plug
* * * * *