Claims:1. A method for manufacturing cooking pots (100), comprising -

Drawing a first tri-ply cooking pot with unbent edges (220), (120),

Causing a first bend on the first tri-ply cooking pot (220) at its unbent edges, to yield a second tri-ply cooking pot with edges bent to a first angular degree (240), (140), wherein said causing (140) is characterised by -

Fixing to position, the first tri-ply cooking pot (220) in a manner that the open section formed by the unbent edges thereat is directed upwards, (143),

Assembling along the inner wall of the first tri-ply cooking pot (220), one or more special purpose injection moulds through the open section of the first tri-ply cooking pot (220), wherein said special purpose injection moulds have mould edges bent at the first angular degree, (146), and,

Pressing the unbent edges of the first tri-ply cooking pot (220) upon the mould edges of the one or more assembled special purpose injection moulds until the second tri-ply cooking pot (240) is yielded, (149).

Causing a second bend on the second tri-ply cooking pot (240) at its edges bent to the first angular degree, to yield a third tri-ply cooking pot with edges bent to a second angular degree (260), (160), and,

Processing the third tri-ply cooking pot (260) to yield a final tri-ply cooking pot (280), (180).

2. The method as claimed in claim 1, wherein drawing the first tri-ply cooking pot (220), (120), comprises -

fixing a sheet of tri-ply material such that its flat blank is constrained and central portion is placed over a die, wherein said die has the same shape and dimension of the first tri-ply cooking pot (220), (124), and,

punching the fixed tri-ply material sheet at its central portion, one or more times, until the first tri-ply cooking pot (220) is yielded (128).

3. The method (100) as claimed in claim 1, wherein causing the second bend on the second tri-ply cooking pot (240) at its edges, to yield the third tri-ply cooking pot (260), (160), comprises -

placing the second tri-ply cooking pot (240) in a hollow pot holder such that its open section is directed outwards (162),

inserting a pneumatic cylinder into the placed second tri-ply cooking pot (240), through its open section, so as to lock the placed second tri-ply cooking pot (240) to position (164),

rotating the locked second tri-ply cooking pot (240) at a rotational speed ranging between 1400 to 1500 rpm (166), and,

moving a bending roller over and in contact with the edges of the second tri-ply cooking pot (240) so as to apply an inward pressure thereat, wherein said inward pressure bends the edges of the second tri-ply cooking pot (240) to a second angular degree and yields the third tri-ply cooking pot (260), (168).

4. The method (100) as claimed in claim 1, wherein the processing the third tri-ply cooking pot (260) to yield the final tri-ply cooking pot (280), (180), includes attaching parts and fixtures upon the third tri-ply cooking pot (260) to yield a completed article, and, treating, by way of polishing, buffing, hard – anodising, or other physical or chemical methods, said completed article, to yield the final tri-ply cooking pot (280).

5. The method (100) for manufacturing a 5 ltrs inner lid pressure cooker, said method comprising –

Drawing, using a PLC coded automated means, a first tri-ply cooking pot (220), (120), by –

fixing a 2.5mm thick sheet of tri-ply material such that its flat blank is constrained and central portion is placed over a die, wherein said die has a diameter of about 180 mm, height of about 160 mm, and thickness of about 2.5 mm, (124), and,

punching the fixed tri-ply material sheet at its central portion, one or more times, with punching force ranging between 140 and 160 tons, until the first tri-ply cooking pot (220) having same size and dimensions as the die, is yielded (128);

Causing the first bend on the unbent edges of the first tri-ply cooking pot (220), to yield the second tri-ply cooking pot having edges bent to 35 to 55 degrees relative to vertical axis (240), wherein said causing (140) comprises –

Fixing to position, the first tri-ply cooking pot (220) in a manner that the open section formed by the unbent edges thereat is directed upwards (143),

Assembling along the inner wall of the first tri-ply cooking pot (220), one or more special purpose injection moulds made of die steel or nickel-based steel, wherein said special purpose injection moulds have mould edges bent to 35 to 55 degrees relative to vertical axis (146), and,

Pressing, using a double acting mechanical or hydraulic press, the unbent edges of the first tri-ply cooking pot (220) upon the mould edges of the one or more assembled special purpose injection moulds with a force of 200 to 250 tons, until the second tri-ply cooking pot (240) is yielded, (149);

Causing the second bend on the 35 to 55 degree bent edges of the second tri-ply cooking pot (240), to yield the third tri-ply cooking pot with edges bent to 90 degrees relative to vertical axis (260), wherein said causing (160) comprises –

placing the second tri-ply cooking pot (240) in hollow pot holder such that its open section is directed outwards (162),

inserting the pneumatic cylinder into the placed second tri-ply cooking pot (240), through its open section, so as to lock the placed second tri-ply cooking pot (240) to position (164),

rotating, using a pre-configured motor system, the locked second tri-ply cooking pot (240) at a rotational speed of 1440 rpm (166), and,

moving, using a pre-set pneumatic actuator, the bending roller over and in contact with the edges of the second tri-ply cooking pot (240) so as to apply an inward pressure of 15 kg/ mm2 thereat, wherein said inward pressure bends the edges of the second tri-ply cooking pot (240) to 90 degrees relative to vertical axis and yields the third tri-ply cooking pot (260), (168);

Processing the third tri-ply cooking pot (260) to yield the 5 ltrs inner lid pressure cooker (280), (180), wherein said processing (180) comprises –

buffing the inner and outer surface of the third tri-ply cooking pot (260), (182),

creating a lid (281) configured to fit on top of the third tri-ply cooking pot (260) wherein said lid (281) carries upon its upper surface, a Metallic Safety Plug (MSP) (282), a Grommet (283), and a pressure valve (284) affixing a whistle (285), and, upon its lower surface, a gasket or a cooker sealing ring (286), and, upon its side surface, a lid handle (287), (184),

attaching, to the third tri-ply cooking pot (260), a pot handle (288) configured to lock seamlessly with the lid handle (287), (186); and,

polishing the third tri-ply cooking pot (260) with lid (281) and pot handle (288), to yield the 5 ltrs inner lid pressure cooker (280), (188).
, Description:FIELD OF THE INVENTION

[001]. The present invention pertains to the field of manufacturing cooking pots, and more particularly, to the field of manufacturing inward bent cooking pots made of tri-ply material.

BACKGROUND OF THE INVENTION

[002]. Cooking Pots refer to those cookware which have a base, attached to which is a wall whose edge, whether straight or bent inwards or bent outwards, forms an open section. Examples of Cooking Pots include Sauce Pans and Pressure Cookers. Traditionally, metals such as Iron, Aluminium and Copper, and alloys such as Brass, Bronze, and, Steel were used to manufacture Cooking Pots. However, with time, newer materials were developed for making Cooking Pots with better overall characteristics. One such material which was developed was Tri-Ply Material (“tri-ply”) which essentially was a combination of three layers viz. Food Grade 304 Stainless Steel (to form the inner wall of the cooking pot) and Induction – friendly Magnetic 430 Stainless Steel (to form the outer wall of the cooking pot), sandwiching a layer of highly conductive aluminium in between.

[003]. While the cooking pots made from tri-ply heat up and hold onto heat evenly, and, respond to heat dial quickly due to their excellent heat conduction and distribution properties, their manufacturers are limited in terms of the cooking pots which could be developed. This is because while drawing tri-ply based cooking pots their edges can only be directed outwards or kept straight. Since the edges of tri-ply based cooking pots cannot be directed inwards while being drawn, an entire range of cookware is missed out.

[004]. In order to overcome the foregoing and use tri-ply for inward bent cooking pots, cookware manufacturers have adopted a technique wherein cooking pots are heated red-hot and rotated around their axis, about a bending roller, such that its edges are bent inwards. While this technique somehow manages to bend the edges of the cooking pot inwards, the cooking pots so manufactured have serious deformities due to the different melting points of Stainless Steel (1400 – 1510 oC) and Aluminium (660 oC). Furthermore, this manufacturing technique itself has problems because if, at any time, the unbent cooking pot loses its temperature then it shall have to be re-heated and the entire manufacturing process shall have to be re-initiated.

[005]. This invention, therefore, is directed at addressing the aforesaid problem(s) by offering an efficient method for manufacturing inward bent tri-ply cooking pots which are free of defects/ deformities and are as per industry standards.

SUMMARY OF THE INVENTION

[006]. The present invention is intended to address at least the above-mentioned problem and to provide a suitable solution. Accordingly, an aspect of the present invention is a method for manufacturing cooking pots, comprising, drawing a first tri-ply cooking pot with unbent edges; causing a first bend on the unbent edges of the first tri-ply cooking pot, to yield a second tri-ply cooking pot with edges bent to a first angular degree; causing a second bend on the edges of the second tri-ply cooking pot which were already bent by the first angular degree, to yield a third tri-ply cooking pot with edges bent to a second angular degree; and, processing the third tri-ply cooking pot to yield a final tri-ply cooking pot.

[007]. Other aspects, advantages and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF DRAWINGS

[008]. The above and other aspects, features and advantages of certain exemplary embodiments of the present invention will be more apparent from the detailed description that follows, taken in conjunction with the accompanying drawings, wherein:

[009]. Fig. 1 illustrates a flowchart of a method for manufacturing tri-ply cooking pots with inward bent edges (100); and,
[010]. Fig. 2 illustrates the proceeds of each step of the manufacturing process (100) viz. first tri-ply cooking pot (220), second tri-ply cooking pot (240), third tri-ply cooking pot (260), and, final tri-ply cooking pot (280).

DETAILED DESCRIPTION OF THE INVENTION

[011]. This detailed description has been provided to readily explain the advantages and features of the present invention taken in conjunction with accompanying figures. In this description, various embodiments maybe found which should not be construed as limiting the scope of the invention. Rather these embodiments should be considered for thorough and complete disclosure of the invention and for fully conveying the concept of the invention to those skilled in the art. For the sake of simplicity, various aspects of the method embodiments have been referred using numerals which refer to the same aspects throughout the specification.

[012]. Person skilled in the art would appreciate that the singular forms “a”, “an” and “the” used herein are intended to include the plural forms as well, unless the context clearly indicates otherwise. Person skilled in the art would further appreciate that the terms “comprises” and/or “comprising”, when used in this specification, would specify the presence of stated features, steps, or operations, but would not preclude the presence or addition of other features, steps, or operations.

[013]. It is further emphasized that the scientific and technical terms used herein should be interpreted and construed in a manner consistent with their dictionary meanings. They should not be interpreted and construed in an idealized or overly formal sense, unless the context expressly states so.

[014]. Referring now to the figures, Fig.1 illustrates the process of manufacturing cooking pots in accordance with the invention (100), and, Fig. 2 illustrates the articles yielded after completion of each step of claimed process (100). Referring both these figures simultaneously, it may be seen that the first step of the claimed manufacturing process (100) is that of drawing a first tri-ply cooking pot (220), (120) which, in essence, is a tri-ply cooking pot with unbent edges. Said step of drawing (120) is achieved by fixing a sheet of tri-ply material such that its flat blank is constrained whereas its central portion is placed over a die having the shape and dimension of the first tri-ply cooking pot (220), (124), and thereafter, punching the fixed tri-ply material sheet at its central portion, one or more times, with a specific force (‘punching force’), until the first tri-ply cooking pot (220) is yielded (128). Person skilled in the art would appreciate that said punching at the central portion of the sheet of tri-ply material may either be done mechanically or hydraulically, and, the punching force may be regulated by coding/ configuring a Programmable Logic Controller (PLC) for setting, saving and modifying requisite force parameters on a touch screen, dashboard, or such similar medium.

[015]. As may be seen from Fig.1 and Fig.2 collectively, after the step of drawing (120), the first tri-ply cooking pot with unbent edges (220) is subjected to step (140) pursuant to which a first bend is caused at the unbent edges of the first tri-ply cooking pot (220) so as to yield a second tri-ply cooking pot (240), which, in essence, is a tri-ply cooking pot whose edges are bent upto a first angular degree. Said step (140) comprises the sub steps of fixing the first tri-ply cooking pot (220) to position such that the open section of the first tri-ply cooking pot (220) formed by the general curvature of the unbent edges is directed vertically upwards (143). After being fixed to position, step (140) comprises the sub-step of assembling along the inner wall of the fixed first tri-ply cooking pot (220), one or more special purpose injection moulds through its open section (220), (146), and, pressing the unbent edges of the first tri-ply cooking pot (220) upon the mould edges of the assembled special purpose injection moulds so as to yield the second tri-ply cooking pot (240), (149), which, in essence, is a tri-ply cooking pot whose edges are bent as much as the mould edges, that is, by a first angular degree. Needless to say, said pressing (149) may be accomplished either mechanically or hydraulically or through other automated means operating on pre-fed/ pre-configured inputs. Person skilled in the art would appreciate that since both, sub-step (143) and sub-step (146) are pre-requisites to yielding the second tri-ply cooking pot (240), their order may be interchanged, without deviating from the scope of the invention. Person skilled in the art will understand that since the second tri-ply cooking pot (240) is yielded by bending the unbent edges of the first tri-ply cooking pot (220) to the first angular degree, by pressing said unbent edges on the mould edges (149), it is essential that the special purpose injection moulds be made up of such metals/ alloys which are less ductile and malleable than tri-ply material itself, such metals/ alloys including without limitation, die steel and nickel based steel alloys, both of which have higher tensile strength and material density as compared to tri-ply material.

[016]. In accordance with the invention and as also witnessed by Fig.1 and Fig.2 cumulatively, the second tri-ply cooking pot (240) is subjected to step (160) to cause a second bent at its edges bent at the first angular degree, to further bend them and thus yield a third tri-ply cooking pot (260), which, in essence, is a cooking pot whose edges are bent to a second angular degree. Said step (160) is achieved by placing the second tri-ply cooking pot (240) in hollow pot holder such that its open section is directed outwards (162), inserting a pneumatic cylinder into the placed second tri-ply cooking pot (240), through its open section, to lock it to position (164), rotating the locked second tri-ply cooking pot (240) at a rotational speed ranging between 1400 to 1500 rpm, depending on the size and dimensions of the second tri-ply cooking pot (240), (166), and, moving a bending roller over and in contact with the edges of the second tri-ply cooking pot (240) so as to apply an inward pressure thereat which bends them further to a second angular degree and yields the third tri-ply cooking pot (260), (168). This bending roller is, in essence, a circular disc made of die steel which is cushioned with foam or such like material so as to avoid scratches and abrasions on the edges of the second tri-ply cooking pot (240) when moved thereat. Person skilled in the art would appreciate that the rotating of the locked second tri-ply cooking pot (240), (166), and, moving the bending roller over and in contact with the edges of the second tri-ply cooking pot (240), (168), may be done either mechanically, or through automated means based on pre-set/ pre-configured speed parameters.

[017]. Once the third tri-ply cooking pot (260) is yielded, it is subjected to the last step of this invention, which is processing the third tri-ply cooking pot (260) to yield a final tri-ply cooking pot (280), (180). These final tri-ply cooking pots (280) may include, without limitation, ready to market sauce pans and pressure cookers. As per the invention, said step comprises the sub-steps of attaching parts and fixtures upon the third tri-ply cooking pot (260) to yield a completed article, and, treating said completed article through polishing, buffing, hard – anodising, or other physical or chemical methods so to yield the final tri-ply cooking pot (280).

BEST MODE

[018]. As per the best mode of this invention, the method (100) for manufacturing a 5 litres inner lid pressure cooker (“final pressure cooker”), may be achieved by firstly, drawing a first tri-ply cooking pot (220), (120) which is done by a PLC coded automated means by fixing a sheet of tri-ply material of 2.5 mm thickness such that its flat blank is constrained whereas its central portion is placed over a die having the shape and dimension of the first tri-ply cooking pot (220), (124), and, punching the fixed tri-ply material sheet at its central portion, one or more times, with a specific punching force ranging between 140 to 160 tons, until the first tri-ply cooking pot (220) with a diameter of about 180 mm, height of about 160 mm, and thickness of about 2.5 mm, is yielded (128).

[019]. Once the desired first tri-ply cooking pot (220) is yielded, step (140) is executed which causes a first bend upon the unbent edges of the first tri-ply cooking pot (220) to bend them by a first angular degree of about 35 to 55 degrees relative to vertical axis and thus yield the second tri-ply cooking pot (240). Said step (140) is achieved by fixing the first tri-ply cooking pot (220) to position, such that the open section of the first tri-ply cooking pot (220) formed by the general curvature of the unbent edges is directed vertically upwards (143), and, assembling along the inner wall of the fixed first tri-ply cooking pot (220), one or more special purpose injection moulds made of die steel or nickel-based steel, whose edges are bent upto 35 to 55 degrees relative to vertical axis (146). Once the one or more special purpose injection moulds are assembled in the first tri-ply cooking pot (220), the last step (149) is performed using a double acting mechanical or hydraulic press operating on pre-fed/ pre-configured inputs, which presses the unbent edges of the first tri-ply cooking pot (220) upon the mould edges of the assembled special purpose injection moulds by a force of 200 to 250 tons, so as to yield the second tri-ply cooking pot (240) whose edges are bent by a first angular degree of 35 to 55 degrees relative to vertical axis.

[020]. Upon completion of step (140), the desired second tri-ply cooking pot (240) is subjected to step (160) to cause a second bent at the edges of the second tri-ply cooking pot (240) to bend them further to a second angular degree of 90 degrees relative to vertical axis and thus yield the third tri-ply cooking pot (260). Said step (160) is achieved by placing the second tri-ply cooking pot (240) in hollow pot holder such that its open section is directed outwards (162), inserting the pneumatic cylinder into the placed second tri-ply cooking pot (240), through its open section, to lock it to position (164), rotating, using a pre-configured motor system, the locked second tri-ply cooking pot (240) at a rotational speed of 1440 rpm (166); and, moving, using a pre-set pneumatic actuator, a bending roller made of die steel and cushioned with foam, over and in contact with the edges of the second tri-ply cooking pot (240) so as to apply an inward pressure of 15 kg/ mm2 thereat which bends them further to a second angular degree of 90 degrees relative to the vertical axis and yields the third tri-ply cooking pot (260), (168).

[021]. Once the third tri-ply cooking pot (260) is yielded, it is subjected to the last step of this invention which is processing the third tri-ply cooking pot (260) to yield the final pressure cooker (280), (180). In accordance with the invention, said step (180) comprises the sub-steps of - (a) buffing the inner and outer surface of the third tri-ply cooking pot (260), (182), (b) creating a lid (281) configured to fit on top of the third tri-ply cooking pot (260) wherein said lid (281) carries upon its upper surface, a Metallic Safety Plug (MSP) (282), a Grommet (283), and a pressure valve (284) affixing a whistle (285), and, upon its lower surface, a gasket or a cooker sealing ring (286), and, upon its side surface, a lid handle (287), (184), (c) attaching, to the third tri-ply cooking pot (260), a pot handle (288) configured to lock seamlessly with the lid handle (287), (186) and, (d) polishing the third tri-ply cooking pot (260) with lid (281) and pot handle (288), to yield the final pressure cooker (280), (188).

[022]. The foregoing specification constitutes the entire body of literature to support and enable a method for manufacturing tri-ply cooking pots with inward bent edges in accordance with the invention. While this disclosure and appended claim set is extensive, it has left out the disclosure of obvious equivalents which are included in this invention by way of implication. To explain, please consider the inventive process (100) itself which focuses on bending the edges of an unbent tri-ply cooking pot by second angular degree by cumulative application of steps (140) and (160), among others, but not specifically in that order. Thus, an obvious and implied equivalent included within the scope of this invention would also be an alternate process where the first bend for bending the unbent edges of the first tri-ply cooking pot (220) by first angular degree is caused by step (160) and the sub-steps thereof (instead of step (140)), and, the second bend for further bending the bent edges of the second tri-ply cooking pot (240) upto second angular degree is caused by step (140) and the sub-steps thereof (instead of step (160)). It is further emphasized that the figures annexed herewith should be regarded as illustrative examples of the present disclosure, and not as restrictive manifestations.