Method and device for producing parts made of plastic, and parts made of plastic

Abstract

The embodiments described herein relate to a method and apparatus for producing a component made of plastic, and a component made of plastic suitable as a container or housing for a household appliance or a container. The component comprises a first layer; and a second layer, which at least partially covers the first layer. The present invention can overcome at least one disadvantage of the prior art.

Description

Technical Field

[0001] The invention relates to a method and a device for producing a component having a body comprising two superimposed layers of plastic material.

[0002] The component is particularly suitable as a receiving body or housing for household appliances, such as kettles, toasters, vacuum cleaners, coffee machines, blenders, irons and the like.

[0003] The invention also relates to a component made of plastic material and a household appliance or a container comprising the component. Background Art

[0004] In the background art of the field of household appliances, it is known to manufacture parts or finished products having two or more layers of plastic material at least partially overlapping each other to provide a certain aesthetic appearance. These parts can be used to form the outer structure of an artifact or object, such as, but not limited to, household appliances for use in the home, or glass bottles, bowls, etc.

[0005] It is also known that increasing attention is paid to aesthetic research in the design and production of household appliances for use in the home in order to satisfy consumer tastes, provide an attractive and recognizable aesthetic appearance and make it stand out from similar solutions on the market.

[0006] For example, components defining a containing body for a kettle are known which comprise a first layer of transparent plastic material and a second layer of metal material, in which a plurality of through holes are formed, through which the first layer and therefore the interior of the kettle itself can be seen.

[0007] However, this solution requires that the first layer and the second layer be manufactured separately and then coupled to each other, thereby causing problems of mutual coupling and sealing.

[0008] This aesthetic research has also led to the production of household appliances whose outer structure is made of plastic material, consisting of two layers molded to each other in one piece.

[0009] Also known is a method for manufacturing a household appliance component, which provides for injecting a first layer of plastic material and then injecting a second layer of plastic material. For example, the first injected layer can be a transparent material, while the second layer can be a colored and / or opaque material.

[0010] In particular, the second material layer may be injected only partially relative to the entirety of the outer surface of the part to be obtained, so as to keep the first injected layer at least partially visible, so as to give the final product a pleasing aesthetic appearance. Alternatively, the first layer of injected material may be colored and / or opaque, while the second layer may be a transparent or translucent material so as to make the underlying injected material layer visible.

[0011] Alternatively, the material used has technical characteristics of the mechanical, and / or thermal, and / or aesthetic type, but makes it unsuitable for contact with foodstuffs and therefore cannot be used for the first layer.

[0012] Also known are articles such as bowl or cutlery handles comprising a first material layer completely covered by a second material layer, wherein the first layer is thicker than the second layer and serves as a structural element, while the second layer serves as an aesthetic surface finish.

[0013] Overmolding of a second material layer on a first material layer may be problematic. In fact, during overmolding of the second layer on the first layer, a so-called "washing" of the first layer may occur, thereby creating aesthetic problems, which is particularly noticeable if the outer layer is at least partially transparent.

[0014] Overmolding of materials can be even more complicated in the case of so-called bi-injection processes, in which a step of injecting a second material is performed immediately after a step of injecting a layer of first material.

[0015] Indeed, due to the temperature at which the second material will be melted, in those areas where the cooling rate is lower, a second, unwanted melting of the underlying layer of the previously injected material may occur.

[0016] In order to prevent the problem of remelting of the inner layer, known solutions provide for manufacturing the inner layer from a material having a higher melting point than the material used for the outer layer.

[0017] These solutions imply the use of more precious materials for the inner layer, which is not visible and does not come into contact with the user, resulting in increased costs.

[0018] Therefore, there is a need to develop a method for producing a component made of plastic material, said method and apparatus being able to overcome at least one of the disadvantages of the prior art.

[0019] Another object is to provide a method for producing parts made of plastic material, said method and apparatus being rapid and allowing high productivity and efficiency.

[0020] Another object of the invention is to perfect a method for producing a component made of plastic material comprising an inner layer and an outer layer in order to prevent possible "washing" effects and remelting of the inner layer.

[0021] Another object is to perfect a method for producing a part made of plastic material which allows obtaining a part having a coloured inner layer and having a glossy, transparent outer layer, substantially free of defects.

[0022] Another object is to perfect an efficient and economical method for producing parts made of plastic material, said method allowing high production rates to be obtained while reducing the overall costs.

[0023] The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages. Summary of the invention

[0024] The invention is set forth and characterized in the independent claims. The dependent claims describe further characteristics of the invention or variants to the main inventive idea.

[0025] According to the above objects, the present invention relates to a method and a device for producing a component made of plastic material suitable for constituting a containing body, a casing, a housing, an outer structure and / or an outer body or at least a part thereof of a household appliance in a home.

[0026] Examples of applications of the component according to the invention may be, for example, household appliances such as kettles, toasters, vacuum cleaners, brushes, blenders, microwave ovens, toaster ovens, deep fryers, teapots, coffee machines, ice cream machines, kneading machines, hair dryers, irons, etc.

[0027] The component according to the invention comprises a body made of plastic material, said body comprising a first inner layer of a first material and a second outer layer of a second material at least partially covering the first inner layer.

[0028] According to some embodiments, the second layer completely covers the first layer.

[0029] According to some embodiments, the thickness of the second outer layer is greater than the thickness of the first inner layer.

[0030] According to some embodiments, the component may have a tubular shape, with a circular, polygonal or elliptical cross section, or with a circumference comprising a combination of straight and curved segments. In addition, the component may be axially extended with a constant cross section or a variable cross section with a plurality of concave or convex portions.

[0031] According to some embodiments, the first material may be opaque, or have one color or multiple colors, while the second material may be at least partially transparent, allowing the first opaque layer to be visible through it. This allows to impart a three-dimensional appearance and a partially raised appearance on the final part.

[0032] According to other embodiments, the second transparent outer layer extends beyond the end edge of the first inner layer at least in the axial direction. In this way, the component has a transparent peripheral strip which imparts a transparent and light effect.

[0033] According to some embodiments, the second outer layer may extend beyond the edge of the inner layer, itself solely defining one or more portions of the body, such as a pouring spout, or a handle for a pitcher or carafe, or other decorative features.

[0034] The method according to the invention for producing a component made of plastic material comprises:

[0035] A first step of injecting a first plastic material into a first molding space defined between a punch and a first substrate to form a first inner layer having a first thickness, wherein the first step has a plurality of first operating parameters, the plurality of first operating parameters comprising a first injection temperature and a first injection pressure; and

[0036] A second step of injecting a second plastic material into a second molding space defined between the inner layer obtained in the first step and the second substrate to form a second outer layer having a second thickness, wherein the second step has a plurality of second operating parameters, the plurality of second operating parameters including a second injection temperature and a second injection pressure, wherein the second thickness is greater than the first thickness of the first inner layer.

[0037] Provided for: making the thickness of the second outer layer greater than the thickness of the first inner layer, so as to allow obtaining a lower resistance to the filling flow of the second material and thus reducing the so-called shear stress phenomenon of the material, preventing the formation of aesthetic defects that may be formed due to mechanical friction of the material caused by friction with the mold wall and the first layer of material.

[0038] Providing the second layer with a greater thickness than the first layer also allows obtaining a three-dimensional finish thereon, which confers a particularly unique aesthetic appearance on parts made of plastic material.

[0039] According to some embodiments, the first material and the second material have homogeneous physical properties.

[0040] According to a preferred embodiment, the first material is opaque and the second material is at least partially transparent, thereby allowing the first layer to be visible therethrough.

[0041] This combination of opaque and transparent materials allows to impart three-dimensional and partially convex effects on the final part.

[0042] According to some embodiments, the operating parameters of the second implantation step are different from the operating parameters of the first implantation step.

[0043] According to some embodiments, at least one of the second injection temperature or the second injection pressure is lower than the corresponding first injection temperature and the second injection temperature.

[0044] In this way, by applying less stress to the first layer in terms of temperature / pressure, a possible cleaning effect is prevented from occurring and a remelting of the first material, thereby preventing a possible contamination of the second material.

[0045] According to some embodiments, the second injection temperature and the second injection pressure are both lower than the first injection temperature and the first injection pressure, respectively.

[0046] According to some embodiments, the second injection temperature is 5-10% lower than the first injection temperature.

[0047] Providing the second layer with a greater thickness allows to reduce the injection temperature, since the greater mass of the second material allows to retain heat during the filling of the second mould space without generating undesirable weld lines.

[0048] According to some embodiments, the second injection pressure is 10-30% lower than the first injection pressure.

[0049] Since the thickness of the second molding space is greater than that of the first molding space, the second material can flow even at a lower pressure.

[0050] According to some embodiments, the method provides cooling a first layer of a first material at a first cooling temperature, and cooling a second layer of a second material at a second cooling temperature lower than the first cooling temperature.

[0051] The invention also relates to a device for producing a component made of a plastic material of the above-mentioned type, comprising:

[0052] a first molding assembly including a punch and a first base adapted to define a first molding space having a first width therebetween, and a first injection unit configured to inject a first plastic material into the first molding space; and

[0053] The second molding assembly includes a second base body, wherein the second base body is configured to define a second molding space having a second width together with the first material layer, and the second injection unit is configured to inject a second plastic material into the second molding space.

[0054] According to one aspect of the invention, the second width is greater than the first width.

[0055] According to some embodiments, the first injection unit includes a heating device configured to heat the first plastic material to a first injection temperature, and an injection device configured to inject the first material at a first injection pressure, and the second injection unit includes a heating device configured to heat the second plastic material to a second injection temperature, and an injection device configured to inject the second material at a second injection pressure.

[0056] According to some embodiments, the first heating device and the second heating device can be activated and adjusted independently of each other.

[0057] According to other embodiments, the first molding unit and the second molding unit respectively include a first cooling circuit and a second cooling circuit independent of each other, and the first cooling circuit and the second cooling circuit can be selectively set to cool the first material and the second material than respective cooling temperatures, wherein the second cooling temperature is lower than the first cooling temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] These and other features of the invention will become apparent from the following description of some embodiments, with reference to the accompanying drawings, by way of non-limiting example, in which:

[0059] Figure 1 is a schematic diagram of a component according to an embodiment of the present invention, the component being applied to a household appliance, in the example shown, a kettle;

[0060] Figure 2 yes Figure 1 Sectional view along section line II-II;

[0061] Figure 3 yes Figure 2 an enlarged detail of a portion of

[0062] Figure 4 is a schematic diagram of a component according to another embodiment of the present invention, the component being applied to different household appliances, in the exemplary case a toaster;

[0063] Figure 4a is a three-dimensional view of details of components according to other embodiments of the present invention;

[0064] Figure 4b is a three-dimensional view of a portion of a component according to another embodiment;

[0065] Figure 4c is a three-dimensional view of a portion of a component according to another embodiment;

[0066] Figure 5 is a schematic diagram of an apparatus for producing a component made of a plastic material according to some embodiments;

[0067] Figure 6 is a vertical cross-sectional view of a component at the end of a first step of injecting a first material according to the invention;

[0068] Figure 7 is a vertical cross-sectional view of a component at the end of a second step of injecting a second material according to the invention;

[0069] Figure 8 is during the first injection step Figure 5 A magnified detail of the device;

[0070] Fig. 9 is along Figure 5 A cross-sectional view of the device along section line IX-IX;

[0071] Figure 9a yes Fig. 9 Magnified details of

[0072] Fig.10 is along Figure 6 A cross-sectional view of line XX in FIG.

[0073] Fig.11 is along Figure 5 A cross-sectional view of the device along section line XI-XI in FIG. 1 ; and

[0074] Fig.12 is along Figure 7 Cross-sectional view along line XII-XII in FIG. DETAILED DESCRIPTION

[0075] We will now refer in detail to possible embodiments of the present invention, one or more examples of which are shown in the accompanying drawings. Each example is provided by way of illustration of the present invention and should not be construed as limiting the present invention.

[0076] Before describing these embodiments, we must also clarify that the application of this description is not limited to the details of construction and arrangement of components as described in the following description using the drawings. The present description may provide other embodiments and may be obtained or performed in various other ways. We must also clarify that the words and terminology used herein are for descriptive purposes only and are not to be regarded as limiting.

[0077] The accompanying drawings are used to describe an embodiment of a component 10 made of plastic material, which is suitable for forming a container, shell, housing, external structure and / or external body or at least a part thereof for a household appliance 50 or other objects (such as bowls, water bottles, thermoses, etc.) used in the home.

[0078] Although in the description below, we will mention household appliances such as kettle 50A and toaster 50B by way of example, it should be understood that the component 10 according to the present invention can define a container or shell for other types of household appliances, such as a vacuum cleaner, a brush, a blender, a microwave oven, an electric oven, a deep fryer, a teapot, a coffee maker, an ice cream maker, a kneader, a hair dryer, an iron, etc.

[0079] The component 10 according to the invention comprises a first inner layer 11 and a second outer layer 12 at least partially overlapping the first inner layer 11 .

[0080] According to some embodiments, component 10 has only two layers, a first layer 11 and a second layer 12 .

[0081] According to a preferred embodiment, the first layer 11 and the second layer 12 may be made of a plastic material, such as a heat-resistant polymer material.

[0082] According to a possible embodiment, the first layer 11 and the second layer 12 may be made of materials having similar features and properties.

[0083] According to a possible embodiment, the first layer 11 and the second layer 12 may be made of a material having inhomogeneous characteristics and properties.

[0084] According to some embodiments, such as a household appliance suitable for use in processing food, the first layer 11 and the second layer 12 may be made of a resin suitable for the food field, such as polypropylene.

[0085] According to a possible embodiment, it can be provided that only the first layer 11 is suitable for use in the food sector, while the second layer 12 is not.

[0086] According to other embodiments, the first layer 11 and / or the second layer 12 may be made of thermoplastic resins of different properties depending on the function of the application.

[0087] According to some embodiments, the first layer 11 may be made of a first opaque material, or of one color or multiple colors, and the second layer 12 may be made of a second at least partially transparent material, allowing the first opaque inner layer 11 to be visible therethrough.

[0088] A transparent or translucent layer is one that can be penetrated by luminous radiation throughout its entire thickness, making objects outside it visible.

[0089] This allows to impart a three-dimensional and partially raised appearance to the final part 10 .

[0090] According to some embodiments, the first layer 11 and the second layer 12 may be obtained by bi-injection processes.

[0091] According to some embodiments, the first layer 11 has a first thickness S1 , and the second layer 12 has a second thickness S2 , and the second thickness S2 is greater than the first thickness S1 .

[0092] According to some embodiments, the first thickness S1 and the second thickness S2 may be defined as maximum thicknesses of the corresponding layers.

[0093] Advantageously, the ratio between the second thickness S2 of the second layer 12 and the first thickness S1 of the first layer 11 may be in the range of 1.05 to 2.5, more preferably in the range of 1.1 to 2.

[0094] The first layer 11 comprises a first surface 13 which defines the inner surface of the component 10 and which faces the interior of the household appliance 50 during use.

[0095] The first layer 11 further comprises a second surface 14 opposite the first surface 13 , on which the second outer layer 12 is positioned in contact.

[0096] According to some embodiments, the first inner surface 13 may have a smooth and uniform development, ie without indentations and / or protrusions.

[0097] The second layer 12 has an outer surface 15 which, during use, defines the outer surface of the component 10 opposite the inner surface 13 and therefore defines the outer surface on which the household appliance 50 is applied.

[0098] According to some embodiments, the outer surface 15 has a three-dimensional finish and includes at least a portion from which a plurality of aesthetic reliefs 16 extend, suitable for imparting a pleasing aesthetic appearance to the component 10 .

[0099] Examples of possible embodiments of the aesthetic relief 16 are shown, for example, in Figure 1 , 2 , 3, 4, 4a and 4b, may include reliefs having parallel ribs, bubbles or hemispheres, diamond shapes, other geometric or non-geometric shapes.

[0100] In particular, the outer surface 15 has a plurality of alternating raised portions 17 and recessed portions 18 that impart a three-dimensional appearance to the component 10 and generally to the household appliance 50 .

[0101] According to some embodiments, the plurality of protruding portions 17 and the plurality of concave portions 18 correspond to regions of the component 10 having different thicknesses relative to the inner surface 13 , respectively.

[0102] According to one possible embodiment, the plurality of protruding portions 17 are configured as vertical ribs that are adjacent to each other and arranged substantially parallel to each other.

[0103] According to possible variants, ribs arranged horizontally or obliquely can be provided, or also projections or reliefs having a helix or spiral-shaped development.

[0104] According to another embodiment, Figure 4a As shown, the protrusions 17 may be configured as spherical or bubble-shaped portions adjacent to each other, evenly distributed, or in any desired arrangement.

[0105] According to another embodiment, Figure 4b As shown, the raised portions 17 may be arranged as pyramids adjacent to one another and based on polygons, in this particular case rectangular.

[0106] According to other variants not shown, the relief 16 may present other shapes, even non-geometric shapes, such as a flower, a heart, etc.

[0107] According to some embodiments, component 10 may have a tubular shape.

[0108] Depending on the needs or the function of the application, the cross-section of the component 10 may have a circular, polygonal or elliptical shape, or have a perimeter including a combination of straight and curved segments.

[0109] Furthermore, the component 10 may have a constant cross section extending in the axial direction, or may be variable with concave or convex portions.

[0110] According to other embodiments, the component 10 may have an open curved shape and be configured to be connected to other similar components 10 , or even to different elements, so as to together form a housing or casing of the household appliance 50 .

[0111] According to some embodiments, the second outer layer 12 completely covers the first inner layer 11 .

[0112] In other possible embodiments, the second layer 12 has an outer end edge 23 which extends in the axial direction X beyond the inner end edge 24 of the first layer 11 .

[0113] More specifically, in the described embodiment, a portion of the second layer 12 actually protrudes beyond the first layer 11 in the axial direction.

[0114] In this way, the component 10 has a peripheral band 25 having a single layer made of a second material, in particular of a transparent type. This transparent peripheral band 25 gives the component 10 a light and three-dimensional appearance.

[0115] According to other embodiments, the second layer 12 may extend in other portions relative to the body of the component 10, such as the spout 51 or the handle 52 of the kettle 50A, to impart further brightness.

[0116] According to some embodiments, the first inner layer 11 comprises a plurality of filling channels or a plurality of cavities 19 throughout its thickness.

[0117] The plurality of filling channels or cavities 19 have a shape and position that correlates to the shape and position of the plurality of recessed portions 18 of the outer surface 15 .

[0118] In particular, a plurality of filled cavities 19 may be formed in the thickness of the first layer 11 and corresponding to the second surface 14 to follow the shape of the outer surface 15 of the second layer 12 defined by the aesthetic relief 16 (i.e. by alternating between a plurality of raised portions 17 and a plurality of recessed portions 18).

[0119] Advantageously, the plurality of filling cavities 19 are able to at least partially compensate for the differences in thickness between the plurality of convex portions 17 and the plurality of concave portions 18 .

[0120] In other words, the second outer layer 12 has a substantially constant thickness along the transverse extension of the component 10 , or in any case a substantially constant average thickness, apart from small deviations from the average, for example of the order of 10-20%.

[0121] The first inner layer 11 has a variable average thickness in the transverse direction of the component 10 .

[0122] According to some embodiments, the transition area 20 may be configured to have a slope shape, wherein the transition area 20 is interposed between portions of the second surface 14 including the plurality of filled cavities 19 and portions of the second surface 14 not including the plurality of filled cavities 19 .

[0123] Advantageously, the transition zone 20 having a beveled shape prevents or at least limits the accumulation of heat during the step of injecting the second material to produce the second layer 12 and thus prevents an undesired remelting of the first material forming the first layer 11 .

[0124] In this way, corrosion caused by mechanical friction resulting from the flow of the second material is also reduced.

[0125] According to some embodiments, component 10 may include a transparent window 22 adapted to allow a user to see therethrough.

[0126] For example, in the case of the kettle 50A, the user can check the water level contained in the containing body composed of the component 10 by means of the transparent window 22 .

[0127] In other forms of implementation, window 22 may be configured to allow a user to see possible additional features of the appliance, such as a thermostat or timer of toaster 50B.

[0128] In other forms of embodiment, the window 22 may be configured to allow the user to see possible internal components of the household appliance 50 and / or have visibility of the product being cooked, or also to verify the accumulation of dust in the collection container of the vacuum cleaner.

[0129] According to some embodiments, the window 22 may be made directly with the aid of the second transparent outer layer 12 .

[0130] In particular, the first layer 11 may contain holes 21 or slits substantially having the shape of the windows 22 to be obtained.

[0131] On the contrary, it is possible to obtain a second layer 12 which substantially covers the first layer 11 so as to completely cover the holes 21 or grooves in continuity with the outer surface 15 .

[0132] According to a possible solution, the component 10 may provide a different surface finish of the second layer 12 corresponding to the window 22, for example a substantially flat and smooth finish, to allow better visibility therethrough.

[0133] Advantageously, the window 22 thus made does not require any special assembly, or any packaging or other device capable of ensuring its airtight sealing. In fact, the window 22 thus made ensures an optimal seal and prevents possible liquids, steam or dust contained in the household appliance from leaking from the inside to the outside, and conversely also prevents penetration from the external environment into the inside.

[0134] Reference here Figures 5 to 12 The described embodiment also relates to a device 26 for producing a component 10 .

[0135] The apparatus 26 comprises a first molding assembly 27 configured to produce the first layer 11 and a second molding assembly 28 configured to produce the second layer 12 .

[0136] In one embodiment of the apparatus 26 , the first molding assembly 27 is positioned adjacent to, abutting, and proximate to the second molding assembly 28 .

[0137] According to some embodiments, the first molding assembly 27 and the second molding assembly 28 are positioned one after the other and can be made to function directly successively in time in order to obtain the finished component 10 by a single process.

[0138] According to some embodiments, the first molding assembly 27 includes a punch 29 and a first molding base 30 adapted to cooperate to define a first molding space V1 therebetween, and a first injection unit 31 configured to inject a first plastic material into the first molding space V1 .

[0139] According to some embodiments, the first molding space V1 has a first maximum width W1 that is consistent with the first thickness S1 of the first layer 11. max .

[0140] According to some embodiments, the first injection unit 31 includes a first heating device 53 configured to heat the first plastic material to a first injection temperature T1.

[0141] According to some embodiments, the punch 29 has a contrast surface 32 configured to define in negative the shape of the inner surface 13 of the first layer 11 of the component 10 .

[0142] According to some embodiments, contrasting surface 32 may be substantially uniform and smooth.

[0143] For example, in the case of a component 10 suitable for manufacturing a kettle 50A, the punch 29 may have a generally truncated cone shape, whereas in the case of a component 10 suitable for manufacturing a toaster 50B, the punch 29 may have a parallelepiped shape with a quadrilateral cross section.

[0144] The first substrate 30 includes a first molding surface 33 configured to define the shape of the second surface 14 of the first layer 11 in an inverted manner.

[0145] According to some embodiments, the first molding matrix 30 may include one or more first molding cheeks 37 configured to be positioned adjacent to each other during use to define a single first molding surface 33 of the first molding matrix 30 .

[0146] According to some embodiments, the first molding surface 33 includes at least a portion having a plurality of first molding ridges 38 protruding within the first molding space V1 during use.

[0147] The plurality of first molding ridges 38 define in an inverted manner the shape of the filling cavity 19 to be produced in the first layer 11 .

[0148] According to some embodiments, the second molding assembly 28 includes a second molding base 34 having a second molding surface 35 adapted to define the shape of the outer surface 15 of the component 10 in an inverted manner.

[0149] The second molding matrix 34 is adapted to cooperate with the second surface 14 of the first material layer 11 during use to define a second molding space V2 therebetween.

[0150] According to some embodiments, the second molding space V1 has a second width W2 that is consistent with the second thickness S2 of the second layer 12. max , the second width W2 max Greater than the first width W1 max .

[0151] According to some embodiments, the second width W2 max With the first width W1 max The ratio between is between 1.05 and 2.5, preferably between 1.1 and 2.

[0152] The second molding assembly 28 further includes a second injection unit 36 ​​configured to inject a second plastic material into the second molding space V2 .

[0153] According to some embodiments, the second injection unit 36 ​​includes a second heating device 54 configured to heat the second plastic material to a second injection temperature T2.

[0154] According to some embodiments, the first heating device 53 and the second heating device 54 can be activated and adjusted independently of each other.

[0155] According to some embodiments, the second molded base 34 comprises one or more second molded cheeks 39 .

[0156] In particular, the second moulding cheeks 39 are configured to be positioned adjacent to each other during use to define a single second moulding surface 35 of the second moulding base 34 .

[0157] According to some embodiments, on at least a portion of the second molding surface 35, a plurality of cavities 40a are formed alternately with corresponding molding reliefs 40b.

[0158] In particular, the cavity 40 a and the molded relief 40 b are able to define, in an inverted manner, the shape of the aesthetic relief 16 present on the outer surface 15 .

[0159] Therefore, the plurality of cavities 40 a and the plurality of mold reliefs 40 b have shapes and sizes that are related to the shapes and final sizes of the plurality of protruding portions 17 and the plurality of recessed portions 18 of the outer surface 15 .

[0160] The plurality of cavities 40 a and the plurality of mold reliefs 40 b are associated with the plurality of mold ridges 38 of the first mold base 30 .

[0161] In other words, the plurality of cavities 40 a and the plurality of molding reliefs 40 b of the second molding base 34 have shapes, sizes, and positions that coordinate with the shapes, sizes, and positions of the plurality of molding ridges 38 of the first molding base 30 .

[0162] In particular, during use, the plurality of molded reliefs 40 b are positioned in a position that correlates with the position of the plurality of molded ridges 38 .

[0163] According to some embodiments, the plurality of first moulding cheeks 37 and the plurality of second moulding cheeks 39 are exchangeable, making it possible to produce parts 10 having different aesthetic shapes with the same device 26 .

[0164] For example, depending on the final appearance that the part 10 must have, it is possible to provide sets of first and second forming cheeks 37 , 39 having different surface finishes.

[0165] According to other embodiments, the first molding component 27 comprises at least one coupling protuberance 41 configured to define a hole 21 or a gap or an empty portion without the first material in the first layer 11 and simultaneously separate the punch 29 and the first substrate 30 from each other.

[0166] According to some embodiments, at least one coupling protuberance 41 is provided on one of the first plurality of moulding cheeks 37 .

[0167] In particular, the coupling protrusion 41 is configured to cooperate with the punch 29 to define and limit a portion of the first molding space V1 and prevent the first material from entering therein.

[0168] According to some embodiments, the coupling protuberance 41 is configured to create coupling with minimal contact with the punch 29 so as to preserve the finish and gloss of the contrasting surface 32 of the punch 29 .

[0169] According to some embodiments, for example, Figure 8 Description The coupling protuberance 41 comprises at least one protruding abutment element 42 adapted to be positioned in contact with the contrasting surface 32 of the punch 29 so as to define a blank space or cavity 43 between the punch 29 and the corresponding first moulding surface 33 .

[0170] According to a further embodiment, a coupling protuberance 41 may be provided on the punch 29 , possibly providing for forming a cavity 43 between the punch 29 and the first matrix 30 situated on the punch 29 , and more particularly along the contrast surface 32 .

[0171] According to some embodiments, for example, Fig.10 Description. The coupling protuberance 41 may comprise a pair of abutment elements 42, or even one annular abutment element, suitable for delimiting a cavity 43, separating it from the first moulding space V1.

[0172] During use, the plurality of abutment elements 42 are configured to rest and press against the surface 32 of the punch 29 to ensure a gas-tight seal of the cavity 43 .

[0173] In this manner, the first molding space V1 is confined in a corresponding region in which the holes 21 are provided in the first layer 11 .

[0174] According to some embodiments, the cavity 43 may have a height defined by the distance between the punch 29 and the respective facing surfaces of the first substrate 30 , said height being between a few hundredths of a millimeter and a few tenths of a millimeter.

[0175] According to some embodiments, the plurality of abutting elements 42 have a width of a few tenths of a millimeter, for example between 0.2 and 1.5 millimeters.

[0176] Width values ​​between 0.2 and 0.9 mm allow the contact between the punch 29 and the base body 30 to be reduced to a minimum, thereby obtaining a cavity 43 with a larger area.

[0177] Slightly larger width values, for example between 0.9 and 1.5, have the only disadvantage of a slight reduction in the area of ​​the cavity 43. Slightly larger width values ​​allow ensuring a gas-tight seal between the punch 29 and the base 30 even at lower closing forces, or where less precision is required.

[0178] According to some embodiments, there may be one or more coupling protuberances 41 having the same or different shapes from each other, depending on the shape and size of the hole 21 to be obtained.

[0179] For example, when the component 10 is applied to a kettle 50A, there may be a first coupling ridge 41, a second coupling ridge 41, and a third coupling ridge 41, wherein the first coupling ridge 41 is suitable for making a window 22 ( 22 ) for controlling the water level. Fig.10 ), the second connection ridge 41 is used to manufacture the nozzle 51, and the third connection ridge 41 is used to manufacture the transparent peripheral band 25 ( Fig.10 ).

[0180] In some embodiments, the abutment element 42 may be shaped according to the shape of the window 22 to be obtained in the component 10 .

[0181] In other embodiments, the abutment element 42 may be shaped to define the shape of the end edge 24 of the first layer 11 .

[0182] Advantageously, the presence of the cavity 43 between the punch 29 and the first molded matrix 30 allows the finish and gloss of the contrasting surface 32 of the punch 29 to be maintained even after several molding cycles.

[0183] According to some embodiments, the first injection unit 31 and the second injection unit 36 ​​each include at least one injection device 44 and at least one injection channel 45, and the injection channel 45 fluidically connects the corresponding injection device 44 to one of the first injection space V1 or the second injection space V2.

[0184] According to some embodiments, a plurality of injection devices 44 may also be provided for each injection unit 31 , 36 .

[0185] According to some embodiments, at least one injection channel 45 is formed in at least one first molding cheek 37 and in at least one second molding cheek 39 .

[0186] According to some embodiments, the apparatus 26 may include, for each molding assembly 27 , 28 , a respective first cooling circuit 46 and a second cooling circuit 47 .

[0187] According to some embodiments, the first cooling circuit 46 and the second cooling circuit 47 are independent of each other and are configured to cool the first layer 11 and the second layer 12 at cooling temperatures T3 , T4 different from each other, respectively.

[0188] According to some embodiments, the first cooling circuit 46 is configured to cool the first layer 11 at a first cooling temperature T3, and the second cooling circuit 47 is configured to cool the second layer 12 at a second cooling temperature T4 lower than the first cooling temperature T3.

[0189] The first cooling circuit 46 comprises one or more cooling channels 48 and a unit for pumping a refrigerant fluid, or a heat exchanger of a known type with a refrigeration circuit and not shown in the figures.

[0190] The second cooling circuit 47 comprises one or more cooling channels 49 and a unit for pumping a refrigerant fluid, or a heat exchanger of a known type having a refrigeration circuit and not shown in the figures.

[0191] According to some embodiments, the cooling channels 48 , 49 may pass through at least one of the first mold cheek 37 and / or the second mold cheek 38 and / or the punch 29 .

[0192] In particular, the cooling channels 48 , 49 are configured to allow passage of a refrigerant fluid therein, such as water, emulsion and / or oil.

[0193] Refer to this Figures 5 to 12 The described embodiments also relate to a method for producing the component 10 .

[0194] The method comprises: a first step of injecting a first plastic material to produce a first layer 11 having a first thickness S1; and a second step of injecting a second plastic material to produce a second layer 12, wherein the second thickness S2 of the second layer is greater than the first thickness.

[0195] According to some embodiments, the method provides for injecting a first material with a first operating parameter and injecting a second material with a second operating parameter having a different value from the first operating parameter.

[0196] According to some embodiments, due to the different and greater thickness of the second layer 12 relative to the first layer 11, lower operating parameters of temperature and pressure can be used for the production of the second layer 12, thereby improving the stability and brightness of the surface and reducing deformation that may occur in the post-shrinkage step.

[0197] According to some embodiments, the method provides for: positioning the punch 29 and the first molding base 30 relative to each other so as to define a first molding space V1 therebetween, and injecting the first material into the first space V1 thus defined. Figure 5 The right hand part of Fig. 9As shown, the first molding space V1 is defined between the contrast surface 32 and the first molding surface 33 of the punch 29 .

[0198] According to some embodiments, the method provides for injecting the first material with defined temperature and pressure parameters.

[0199] According to some embodiments, the method provides for injecting the first material at a first temperature T1 comprised between 150°C and 260°C, at least in the case of propylene.

[0200] According to other embodiments, the first temperature T1 is comprised in the range of 120°C to 240°C, preferably in the range of 160°C to 220°C, even more preferably in the range of 180°C to 200°C.

[0201] According to one embodiment, the method provides for: using a pressure of 700 kg / cm 2 and 1300kg / cm 2 The first material is injected at a first pressure P1 between the two.

[0202] According to other embodiments, the first pressure P1 may be 750 kg / cm 2 and 1250kg / cm 2 between 800 kg / cm 2 and 1200kg / cm 2 between.

[0203] The first implantation step allows obtaining a first layer 11 ( Figure 6 and 10 ).

[0204] According to some embodiments, during the first implantation step, the method may include cooling the first layer 11 to a first cooling temperature T3.

[0205] According to some embodiments, in order to cool the first layer 11 , the method may include circulation of a refrigerant fluid in the first cooling circuit 46 in order to cool at least one of the first substrate 30 and / or the punch 29 .

[0206] According to some embodiments, the method provides for using a first cooling temperature T3 comprised in the range between 35°C and 55°C, more preferably in the range between 40°C and 50°C.

[0207] Subsequently, the method provides positioning the punch 29 on which the first layer 11 is formed in the second molding assembly 28 to position the second base body 34 so as to define a second molding space V2 together with the second surface 14 of the first layer 11 .

[0208] The second molding space V2 is defined between the second surface 14 of the first layer 11 including the plurality of filling cavities 19 and the second molding surface 35, for example Figure 7 The right hand side of Fig.11 shown.

[0209] The method then comprises a second injection step, in which a second plastic material is injected into the second moulding space V2 at a second injection temperature T2 and a second injection pressure P2.

[0210] According to a possible embodiment, the second implantation step immediately follows the first implantation step.

[0211] According to one embodiment, the method provides for using a second temperature T2 which is lower than the first injection temperature T1 .

[0212] According to a preferred embodiment, the second injection temperature T2 is comprised in the range of 0.90 to 0.95 times the first injection temperature T1. In other words, the second injection temperature T2 is 5 to 10% lower than the first injection temperature T1.

[0213] According to one embodiment, the second pressure P2 may advantageously be lower than the first pressure P1 .

[0214] According to one embodiment, the second pressure P2 may be included in the range of 0.70 to 0.90 times the first pressure P1. In other words, the second pressure P2 is 10 to 30% lower than the first pressure P1.

[0215] The second injection step produces the second outer layer 12 of the component 10 .

[0216] According to some embodiments, during the second implantation step, the method may include cooling the second layer 12 to a second cooling temperature T4.

[0217] According to some embodiments, in order to cool the second layer 12 , the method may include circulation of a refrigerant fluid in a second cooling circuit 47 in order to cool at least one of the second substrate 34 and / or the punch 29 to a second cooling temperature T4 .

[0218] According to some embodiments, the second cooling temperature T3 may be between 15% and 25% lower than the first cooling temperature T4.

[0219] According to a preferred embodiment, the second cooling temperature T4 may be in the range of 25°C to 45°C, more preferably in the range of 30°C to 40°C.

[0220] According to other embodiments, the method provides for producing a second outer layer 12 , the outer surface 15 of which has a three-dimensional finish comprising a plurality of convex portions 17 and a plurality of concave portions 18 alternating.

[0221] According to other embodiments, the method provides for producing at least one transparent window 22 .

[0222] To produce the window 22 , the method provides for producing a hole 21 or a slit in the first layer 11 and, during a second injection step, covering the hole 21 or the slit with a second material, wherein the second material is transparent in this case.

[0223] According to some embodiments, at the end of the second injection step, the method comprises separating the molding punch 29 from the second molding matrix 35 and extracting the component 10 .

[0224] Experimental example:

[0225] The applicant has conducted experimental tests and confirmed that the injection and cooling temperatures T1, T2, T3, T4 and the injection pressures P1 and P2 can be changed within the considered range according to the difference between the thicknesses S1 and S2 of the first layer 11 and the second layer 12.

[0226] Table 1 shows possible ratios between operating temperatures and pressures that can be used in the first and second implantation steps, said ratios being related to the ratio between the thicknesses S1 , S2 .

[0227] Table 1:

[0228]

[0229] Obviously, modifications and / or additions of parts or steps may be made to the component 10 , the device 26 and the method without departing from the field and scope of the present invention.

[0230] It is also clear that, although the invention has been described with reference to a few specific examples, a person skilled in the art will of course be able to realize many other equivalent forms of component 10, device 26 and method having the characteristics of the scope of protection as set out in the claims, all of which therefore belong to the field of protection defined thereby.

Claims

1. A device for producing a component (10) made of plastic, comprising: A first molding assembly (27) includes a punch (29) and a first substrate (30) having a first molding surface (33) adapted to define a first width (W1 max ), and a first injection unit (31) configured to inject a first opaque plastic material into the first molding space (V1) and obtain a first layer (11); and A second molding assembly (28) comprising a second substrate (34) having a second molding surface (35) adapted to define, together with the first layer (11) of the component (10), a second width (W2 max ), and a second injection unit (36) is configured to inject a second transparent plastic material into the second molding space (V2) and obtain a second layer (12), thereby allowing the first layer (11) to be visible through the second layer (12), Characterized in that the second width (W2 max ) is greater than the first width (W1 max ); wherein the second layer (12) extends beyond the end edge of the first layer (11) in the axial direction so that the component (10) has a transparent peripheral band, or the second layer (12) extends beyond the edge of the first layer (11) and itself alone defines one or more parts of the body of the component (10); The first molding component (27) further comprises at least one coupling protuberance (41), the coupling protuberance (41) comprising at least one protruding abutment element (42) located on the first substrate (30), the abutment element (42) being adapted to be positioned in contact with a contrasting surface (32) of the punch (29) and configured to define a portion of a hole (21) or a slit in the first layer (11) free of the first opaque plastic material and simultaneously to separate the punch (29) and the first substrate (30) from each other, wherein the hole (21) or the slit is configured to be completely covered by the second transparent plastic material.

2. The device according to claim 1, characterized in that: The second width (W2) of the second molding space (V2) max ) and the first width (W1) of the first molding space (V1) max ) is between 1.0 and 2.

5.

3. The device according to claim 1, characterized in that: The first injection unit (31) comprises a first heating device (53) configured to heat the first opaque plastic material to a first injection temperature (T1), and the second injection unit (36) comprises a second heating device (54) configured to heat the second transparent plastic material to a second injection temperature (T2), wherein the first heating device (53) and the second heating device (54) are at least activated and regulated independently of each other.

4. The device as claimed in claim 1, characterized in that: The first molding assembly (27) and the second molding assembly (28) respectively include a first cooling circuit (46) and a second cooling circuit (47) which are independent of each other and can be selectively set to cool the first opaque plastic material and the second transparent plastic material at respective cooling temperatures (T2, T1).

5. A component made of plastic produced using the apparatus of claim 1, the component being suitable for forming a container or housing for a kettle (50A) or a toaster (50B), comprising: a first layer (11) made of a first opaque plastic material; and a second layer (12) made of a second transparent plastic material, which at least partially covers the first layer (11), the first layer (11) being visible through the second layer (12); Characterized in that the first layer (11) has a first thickness (S1), and the second layer (12) has a second thickness (S2) greater than the first thickness (S1); wherein the second layer (12) extends beyond the end edge of the first layer (11) in the axial direction so that the component (10) has a transparent peripheral band, or the second layer (12) extends beyond the edge of the first layer (11) and itself alone defines one or more parts of the body of the component (10); The first layer (11) is provided with a hole (21) or a slit, and the second transparent plastic material completely covers the hole (21) or the slit.

6. The component according to claim 5, characterized in that: The second layer (12) comprises an outer surface (15) having a three-dimensional finish, the three-dimensional finish comprising a plurality of alternating convex portions (17) and a plurality of concave portions (18); and The first layer (11) includes, in its thickness, a plurality of filling channels or a plurality of cavities (19) related to the shape and position of the plurality of recessed portions (18) of the second layer (12), suitable for at least partially compensating for the thickness difference between the plurality of protruding portions (17) and the plurality of recessed portions (18).

7. A kettle (50A) or a toaster (50B), characterized in that: The kettle (50A) or toaster (50B) comprises a container or housing, which is at least partially made of a component (10) according to any one of claims 5 to 6.

8. A method for producing a component (10) made of plastic, having a tubular shape and suitable for forming a container or housing for a kettle (50A) or a toaster (50B), using a device as claimed in claim 1, the method comprising: A first step of injecting a first opaque plastic material into a first molding space (V1) defined between a punch (29) and a first substrate (30) to form a first layer (11) having a first thickness (S1), wherein the first step has a plurality of first operating parameters, the plurality of first operating parameters comprising a first injection temperature (T1) and a first injection pressure (P1); and a second step of injecting a second transparent plastic material into a second molding space (V2) defined between the first layer (11) obtained in the first step and the second substrate (34) to produce a second layer (12) having a second thickness (S2) so as to allow the first layer (11) to be visible through the second layer (12), wherein the second step has a plurality of second operating parameters, the plurality of second operating parameters comprising a second injection temperature (T2) and a second injection pressure (P2), wherein the second step is performed immediately after the first step, It is characterized in that The second thickness (S2) of the second layer (12) is greater than the first thickness (S1) of the first layer (11), and at least one of the plurality of second operating parameters of the second step is lower than a corresponding parameter of the plurality of first operating parameters of the first step; wherein the second layer (12) extends beyond the end edge of the first layer (11) in the axial direction so that the component (10) has a transparent peripheral band, or the second layer (12) extends beyond the edge of the first layer (11) and itself alone defines one or more parts of the body of the component (10); Therein, in the first step, a hole (21) or a slit is made in the first layer (11), and in the second step, a second transparent plastic material is made to completely cover the hole (21) or the slit.

9. The method according to claim 8, characterized in that: At least one of the second injection temperature (T2) or the second injection pressure (P2) is lower than the first injection temperature (T1) or the first injection pressure (P1), respectively.

10. The method according to claim 8, characterized in that: The first injection temperature (T1) is in the range of 120°C to 270°C, and the second injection temperature (T2) is between 5% and 10% lower than the first injection temperature (T1).

11. The method according to claim 8, characterized in that: The first injection pressure (P1) is 700 kg / cm 2 Up to 1300kg / cm 2 and the second injection pressure (P2) is between 10% and 30% lower than the first injection pressure (P1).

12. The method according to claim 8, characterized in that: providing during said first step cooling said first opaque plastic material in said first moulding space (V1) at a first cooling temperature (T3); And during the second step, cooling of the second transparent plastic material in the second molding space (V2) at a second cooling temperature (T4) is provided, wherein the second cooling temperature (T4) is lower than the first cooling temperature (T3).

13. The method according to claim 12, characterized in that: The first cooling temperature (T3) is between 35°C and 55°C, and the second cooling temperature (T4) is between 15% and 25% lower than the first cooling temperature (T3).

14. The method according to claim 8, wherein: The method provides for using a first opaque material having one or more colors and a second at least partially transparent material.

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