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(11) | EP 1 488 864 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Method to produce a steam boiler for a domestic appliance |
| (57) Method to produce a boiler (10) for the production of steam in a domestic appliance.
The boiler (10) comprises a first component (11) and a second component (12) associated
together in order to define a closed compartment (13) into which water to be made
to evaporate is introduced. The method comprises a first manufacturing step, wherein
at least one of the first (11) and the second (12) component is made by means of cold
extrusion, starting from a pellet (21) of substantially pure aluminum. |
FIELD OF THE INVENTION
[0001] The present invention concerns a method to produce a steam boiler for a domestic appliance, such as for example an iron, a steam cleaning device or suchlike. The method according to the present invention comprises at least a cold extrusion step, by means of which, starting from pellets of substantially pure aluminum, the different parts that make up the boiler are made.
BACKGROUND OF THE INVENTION
[0002] Boilers for the production of steam are known, which are associated with a domestic appliance such as for example an iron, a steam cleaning device or suchlike, substantially consisting of two hollow components coupled together, in airtight manner, so as to define a closed compartment into which the water to be evaporated is introduced.
[0003] Such known components can be, simply to give an example, either of the type with two half-shells, bolted or welded together, or of the type with a container hermetically closed by a mating cover.
[0004] A first type of boiler is known wherein the two components are made of stainless steel, made in a mold and welded together. Although such boilers are robust, they do have some disadvantages however, including low heat inertia, high energy consumption and high costs both of the raw material and also of the welding steps.
[0005] Moreover, steel boilers of a known type have considerable difficulties due to their association with heating and control members. In fact, they need a further welding step, after molding, in order to attach elements able to allow the arrangement of control components and components to load the water.
[0006] This further welding step is not only extremely difficult, but also entails a considerable increase in production costs.
[0007] In order to overcome these shortcomings, boilers have been constructed consisting mainly or completely of aluminum components, made by means of pressure die-casting, with consequent high costs since, although the cost of the raw material used is lower, they need relatively long construction times.
[0008] Moreover, possible impurities in the raw material used set off corrosive phenomena and possible blowholes during the molding step, with the risk of even causing small explosions.
[0009] One purpose of the present invention is to perfect a method to produce a steam boiler for a domestic appliance wherein the components of which it consists are made at least mostly of aluminum, but with production techniques that neither require a long time for working them nor consequent high costs.
[0010] The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain this and other purposes and advantages.
SUMMARY OF THE INVENTION
[0011] The present invention is set forth and characterized in the main claims, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea.
[0012] In accordance with the aforesaid purpose, the production method according to the present invention is applied to make a boiler of the type able to generate steam in a domestic appliance, comprising a first component and a second component, associated together so as to define a closed or airtight compartment, into which water to be made to evaporate is able to be introduced.
[0013] According to a characteristic feature of the method according to the present invention, there is at least a first manufacturing step, wherein at least one of either the aforesaid first or second component is made by means of cold extrusion, advantageously starting from a pellet of substantially pure aluminum, that is, where the percentage of aluminum is at least equal to 99%.
[0015] According to a preferential form of embodiment of the present invention, such extrusion is done by pressing the pellet, by means of a shaped punch, against a mating matrix. This pressure determines the deformation of the pellet itself and subsequent shaping thereof until the desired shape is achieved, defined by the punch and matrix.
[0016] The extrusion of the material also guarantees a good surface finishing of the parts and considerably reduces the times and costs of production, since it does not require any pre-heating or pre-forming of the aluminum pellet used to make each component.
[0017] Another advantage of the present invention is that, during extrusion, seatings can be made for further pressing of the resistance, seatings for possible connections, seatings for thermostats or otherwise, without having to perform any further working steps.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] These and other characteristics of the present invention will become clear from the following description of a preferential form of embodiment, given as a non-restrictive example, with reference to the attached drawings wherein:
- fig. 1 shows a lateral section of a first boiler made using the method according to the present invention;
- fig. 2 shows a first component of the boiler in fig. 1;
- fig. 3 shows a second component of the boiler in fig. 1;
- fig. 4 shows a lateral section of a second boiler made using the method according to the present invention;
- figs. 5a, 5b and 5c show some steps of the method according to the present invention to make the component in fig. 2;
- figs. 6a, 6b and 6c show some steps of the method according to the present invention to make the component in fig. 3.
DETAILED DESCRIPTION OF A PREFERENTIAL FORM OF EMBODIMENT
[0019] With reference to fig. 1, a method according to the present invention in this case is applied to make a boiler 10 able to generate steam in a small domestic appliance (not shown in the drawings), such as for example an iron, a cleaning apparatus or suchlike.
[0020] The boiler 10 comprises a container 11 shaped like a glass, substantially cylindrical and closed at the bottom, and a cover 12, able to close the open side of the container 11 in air-tight manner, so as to define a closed compartment 13 to contain the water.
[0021] The container 11 (fig. 2) comprises a lateral wall and a bottom wall 15 on which there are a central protuberance 16, able to cooperate with possible gripping means, of a known type and not shown in the drawings, and a radial abutment shaping 17 which allows to position the boiler 10 angularly with respect to the domestic appliance in which it is installed.
[0022] The cover 12 (fig. 3) comprises an axial pipe 19 to feed the water which extends towards the inside of the compartment 13 and, off-set, a second pipe 20 through which steam is discharged, parallel to the pipe 19, and extending instead towards the outside of the compartment 13.
[0023] The pipes 19 and 20 are able to be connected, in this case, respectively to water pumping means and steam delivery means, of a known type and not shown in the drawings, provided inside the domestic appliance.
[0024] The pipes 19 and 20 can be used irrespectively according to the design needs, to feed the water or to discharge the steam.
[0025] Both the container 11 and the cover 12 are made of substantially pure aluminum, that is, with a percentage of aluminum at least equal to 99%, advantageously between about 99.5% and 99.7%.
[0027] With reference to figs. 5a, 5b and 5c, the container 11 is achieved by means of a process of backward cold extrusion using a punch 22 and a matrix 23, between which a pellet 21 of substantially pure aluminum, easily found on the market, is able to be placed.
[0028] The punch 22 has a lower surface 25 shaped so as to define a part of the profile of the container 11, whereas the matrix 23 has an upper surface 26 shaped so as to define a complementary part of the profile of the container 11.
[0029] In this way, by thrusting the punch 22 with a determinate pressure against the pellet 21, and then against the matrix 23, the pellet 21 is plastically deformed and extruded backwards until it is taken to assume the definitive shape of the container 11.
[0030] The cover 12 is made in the same way, as shown in figs. 6a, 6b and 6c. In this case, a pellet 121 is used, also made of substantially pure aluminum, provided with a through hole 30. To allow to shape the pellet 121, a punch 122 is provided on its lower surface 125 with a pin 27, able to be inserted into the mating through hole 30.
[0031] In this way, during the step of plastic deformation of the material that makes up the pellet 121, the coupling of the pin 27 and the hole 30 prevents the material from plugging, even partly, the pipe 19 that will be formed, thus avoiding subsequent finishing steps for such pipe 19.
[0033] Both the container 11 and the cover 12 are then removed from the respective matrixes 23, 123 and coupled together, for example by means of welding, so as to form the boiler 10 shown in fig. 1.
[0034] According to the variant shown in fig. 4, the boiler, indicated in its entirety by the reference number 110, comprises two half-shells, respectively lower 111 and upper 112, also made in the same way as the container 11 and the cover 12, by means of a backward cold extrusion pass starting from a pellet of substantially pure aluminum. In this case, the lower half-shell 111 and the upper half-shell 112 are substantially cylindrical in shape and are substantially of the same size, so as to constitute the two halves of the boiler 110.
[0035] In this case, the upper half-shell 112 has a pipe 119 through which water is introduced and, as in the previous case, the pellet from which it is made has a hole into which a relative pin provided on the punch is inserted (not shown here).
[0036] During the extrusion step there are also made a possible pressing seating on the lower half-shell 111 for a resistance 31, and possible variations in thickness in order to insert screws to attach elements to control the temperature 32, of a known type and not described in detail here.
[0037] It is clear, however, that modifications and/or additions of steps can be made to the method as described heretofore, without departing from the field and scope of the present invention.
[0038] According to a variant, the shaped surfaces 25, 125 and 26, 126 can be made on suitably shaped elements able to be selectively associated with the punch 22, 122 or the matrix 23, 123, so that such surfaces 25, 125 and 26, 126 can be deliberately interchanged according to the component 11, 111, 12 or 112 to be made.
[0039] It is also clear that, although the present invention has been described with reference to specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of method to produce a steam boiler for a domestic appliance, all of which shall come within the field and scope of the present invention.
1. Method to produce a boiler (10, 110) for the production of steam in a domestic appliance,
said boiler (10, 110) comprising a first component (11, 111) and a second component
(12, 112) associated together in order to define at least a closed compartment (13)
into which water to be made to evaporate is introduced, characterized in that it comprises at least a first manufacturing step, wherein at least one of said first
(11, 111) and second (12, 112) component is made by means of cold extrusion, starting
from a pellet (21, 121) of substantially pure aluminum.
2. Method as in claim 1, characterized in that said cold extrusion provides at least a backward extrusion pass.
3. Method as in claim 1 or 2, characterized in that it provides to use at least punch means (22, 122) able to press said pellet (21,
121) against matrix means (23, 123).
4. Method as in claim 3, characterized in that said punch means (22, 122) comprise at least a shaped surface (25, 125) having a
profile mating with a first part of the profile of said first (11, 111) or second
(12, 112) component.
5. Method as in claim 4, characterized in that said matrix means (23, 123) comprise at least a shaped surface (26, 126) having a
profile mating with a second part of the profile of said first (11, 111) or second
(12, 112) component and complementary to said first part of the profile of said first
(11, 111) or second (12, 112) component.
6. Method as in claim 4 or 5, wherein at least one of said first (11, 111) or second
(12, 112) component comprises a through pipe (19, 20), characterized in that said pellet (121) comprises at least a through hole (30) inside which a mating pin
(27) provided on said shaped surface (125, 126) is able to be arranged.
7. Boiler for the production of steam, produced by means of a method as in any claim
hereinbefore.