Machine and method for the production of a thermoplastic component by injection moulding

Abstract

Machine (1) for the production of a thermoplastic component provided with at least one through-opening therein, comprising: a mould (3) provided with an internal cavity (4) of a shape complementary to the thermoplastic component to be produced; and a thermoplastic material supply assembly (11), which is fluidly connected to the cavity (4) through an injection opening (17) and is adapted to inject the molten thermoplastic material of the thermoplastic component into the cavity (4); the mould (3) comprises a first half -mould (5) and a second half-mould (6), which are adapted to be arranged in abutment one on the other and are shaped in such a way as to delimit the cavity (4), wherein the first half-mould (5) is carried in a movable manner and is movable to and from the second half-mould (6); the machine further comprises a movable slider apparatus (20), which is movably carried by the mould (3) and is adapted to selectively engage a portion of the cavity (4).

Description

[0001] “MACHINE AND METHOD FOR THE PRODUCTION OF A THERMOPLASTIC COMPONENT BY INJECTION MOULDING”

[0002] Cross-reference to related Patent Applications

[0003] This Patent Application claims priority from Italian Patent Application No. 102024000024303 filed on October 30, 2024, the entire disclosure of which is incorporated herein by reference.

[0004] Technical Field

[0005] The present invention relates to a machine and a method for the production of a thermoplastic component by injection moulding.

[0006] State of the Art

[0007] As is known, the injection moulding process of a thermoplastic component essentially provides for melting / softening a thermoplastic polymeric material and injecting it into a mould, within which the thermoplastic material hardens to form the thermoplastic component to be produced.

[0008] It is also known to make through-openings inside the moulded component by means of a subsequent cutting step, directly on the cooled and solidified thermoplastic component. Such cutting operations are generally carried out by means of a hydraulically actuated cutting machine separate and distinct from the machine for the injection moulding of the same thermoplastic component.

[0009] Unfortunately, in general it is somewhat difficult to cut and make through-openings in cooled thermoplastic components of high thickness, for example greater than 4 or 5 millimetres, without damaging the same components, with the obvious limitations that this entails.

[0010] In addition, the subsequent cutting operations have a non-negligible impact on the times and costs of the production process of the thermoplastic component to be produced.

[0011] There is therefore a need to provide a machine and a method for the production of thermoplastic components that is capable of producing thermoplastic components, even of high thickness, provided with through-openings.

[0012] Furthermore, there is a need to provide a machine and a method for the production of thermoplastic components that is capable of producing thermoplastic components with areas of varying thickness.

[0013] There is also a need to provide a machine and a method for the production of multilayer thermoplastic components provided with a graphic sheet inside them. The object of the present invention is to satisfy the above-mentioned needs in an optimised and economical manner.

[0014] Summary of the Invention

[0015] The aforesaid object is achieved by a machine and by a method for the production of thermoplastic components made according to the respective independent claims and preferably, but not necessarily in one of the claims dependent thereon.

[0016] The claims describe preferred embodiments of the present invention forming an integral part of the present description.

[0017] Brief Description of the Drawings

[0018] For a better understanding of the present invention a preferred embodiment is described below, by way of non-limiting example and with reference to the accompanying drawings in which:

[0019] - figure 1 is a schematic sectional view of a machine for the production of thermoplastic components made according to the present invention, with parts removed for clarity and parts shown out of scale,

[0020] - figures 2 and 3 are schematic examples of thermoplastic components which can be produced with the machine illustrated in figure 1,

[0021] - figures 4, 5 and 6 are schematic sectional views of the machine illustrated in figure 1, in as many stages of its operation and with parts removed for clarity and parts shown out of scale, and

[0022] - figure 7 is a perspective and schematic view of a multilayer thermoplastic component made according to the present invention,

[0023] - figure 8 is an exploded view of the component illustrated in figure 7, and

[0024] - figures 9 to 12 are schematic sectional views of a second embodiment of the machine illustrated in figure 1, in some steps of the method for making the multilayer thermoplastic component illustrated in figures 7 and 8.

[0025] Detailed Description of the Invention

[0026] With reference to figure 1, number 1 indicates as a whole a machine for the injection moulding of components in thermoplastic material 100, also known as an injection press.

[0027] With reference to the example illustrated in figure 2, machine 1 is advantageously configured to produce thermoplastic components 100 provided with an internal through -opening Preferably, the component 100 may be provided with a fiill / solid sector 102 that seamlessly surrounds the through-opening 101. In other words, the component 100 may have a substantially annular shape / structure.

[0028] Additionally or alternatively, with reference to the example illustrated in figure 3, machine 1 is advantageously configured to produce components 100 in thermoplastic material provided with at least one sector / zone 104 of reduced thickness with respect to the remaining sectors / zones of the same component 100. More in detail, the component 100 can be provided with the first sector 102 having a thickness si and a second sector 106 having a thickness S2. The thickness S2 may be less than the thickness si. The first sector 102 may advantageously have a substantially annular shape and / or may surround the second sector 106 substantially seamlessly.

[0029] In addition, the thermoplastic component 100 to be produced may have a plate - like / lenticular structure. In other words, the component 100 preferably has two dimensions (width, length) prevailing over the third (height). In addition, the component 100 may have a flat, concave, convex shape and / or a combination of the foregoing.

[0030] The component 100 can be a component adapted to be installed in a motor vehicle, such as for example the lens of a lamp, a mudguard, a panel of the passenger compartment and / or similar components for motor vehicles.

[0031] With reference to the example illustrated in figure 1, machine 1 preferably comprises a support frame 2 (schematically illustrated) with a rigid and self-supporting structure, which is advantageously made of metallic material and is adapted to be placed and optionally also securely anchored to the ground.

[0032] In addition, as known per se and therefore not described in detail, machine 1 comprises a mould or matrix 3. The mould 3 is provided with at least one internal cavity 4 of a shape complementary to the shape of the component in thermoplastic material 100 to be produced.

[0033] As is known, the mould 3 is movable between a closed configuration or position and an open configuration or position. In the closed configuration, the mould 3 delimits the cavity 4. In the open configuration, on the other hand, the mould 3 does not delimit the cavity 4 and / or allows the extraction of the thermoplastic components previously moulded in the cavity 4.

[0034] More in detail, the mould 3 comprises at least a first half-mould 5 or movable plate and a second half-mould 6 or fixed plate, which are adapted to be selectively arranged in abutment with each other and are shaped in such a way as to delimit the cavity 4.

[0035] In the closed configuration, the two half-moulds 5 and 6 are advantageously arranged in abutment one on the other. In the open configuration, on the other hand, the two half-moulds 5 and 6 are arranged spaced apart from each other. Preferably, at least one of the two half-moulds 5 or 6 is provided with a concave portion 7 or groove or seat, which contributes to delimiting the cavity 4 together with the other half-mould 5 or 6 when the mould is closed, that is when the two half-moulds 5 and 6 are brought into abutment one on the other.

[0036] More in detail, the two half-moulds 5 and 6 preferably have a substantially prismatic shape, and are preferably provided respectively with faces 8 and 9 adapted to be arranged in abutment one on the other.

[0037] The concave portion 7 is preferably formed on a face 8 or 9 of the respective half-mould 5 or 6.

[0038] More in detail, in the example shown, the half-mould 6 is provided with the concave portion 7 on its face 9. The face 8 of the half-mould 5 facing the face 9, on the other hand, can be provided with a convexity or projecting portion adapted in use to penetrate at least partially inside the concave portion 7 of the half-mould 6.

[0039] Preferably, at least one of the two half-moulds 5 or 6 is movably carried by the frame 2, such that it can slide to and from the other half-mould 6 along a direction di.

[0040] In the example shown, the half-mould 6 is preferably carried fixedly by the frame 2. The half-mould 5, on the other hand, is preferably carried movably by the frame 2 in such a way that it can slide towards and away from the facing half-mould 6 and can be arranged in abutment thereon.

[0041] More in detail, machine 1 preferably comprises a movement or actuation mechanism 10 of the mould 3 adapted to move, on command, the half-mould 5 to and from the facing half-mould 6.

[0042] Preferably, the movement mechanism 10 is a hydraulically operated movement mechanism.

[0043] More in detail, the movement mechanism 10 preferably comprises a source of pressurised hydraulic fluid 11 adapted to supply a pressurised hydraulic fluid at an outlet.

[0044] In addition, the movement mechanism 10 preferably also comprises an actuator 12, which is fluidically connected to the source 11 to receive the pressurised hydraulic fluid, and is mechanically connected to at least one of the two half-moulds 5 or 6 in order to move it on command. For example, the actuator 12 may comprise one or more hydraulic cylinders, a hydraulic motor associated with a worm screw and / or other similar hydraulic actuator.

[0045] The movement mechanism 10 further comprises valve means 13, fluidically interposed between the source of pressurised hydraulic fluid 11 and the actuator 12 and adapted to control the flow of pressurised hydraulic fluid supplied towards the same actuator 12. Additionally or alternatively, the movement mechanism 10 could also be an electrically driven mechanism and could comprise one or more electric actuators associated with at least one of the two half-moulds 5 or 6.

[0046] In addition, machine 1 is preferably also provided with a mould closing mechanism (not shown) adapted to selectively lock the mould 3 in the closed position. More in detail, the mould closing mechanism is adapted to firmly hold the two half-moulds 5 and 6 in abutment one on the other during the injection and moulding phases of the molten thermoplastic material inside the cavity 4.

[0047] As is known, the mould 3 is generally kept in the closed configuration during the printing of the component 100 and is then arranged in the open configuration to allow the extraction of the previously printed component 100.

[0048] Preferably, the two half-moulds 5 and 6 are made of metallic material, for example steel, aluminium and / or other similar metallic alloys.

[0049] With reference to the preferred embodiment of the present invention, the mould 3 is advantageously a multi-color or multi-material mould, i.e. a mould with a rotary table, known per se and therefore not further described.

[0050] With reference to the example shown, machine 1 comprises a thermoplastic material supply assembly 14, which is fluidly connected to the cavity 4 and is adapted to feed the molten thermoplastic material inside the same cavity.

[0051] More in detail, the thermoplastic material supply assembly 14 may comprise an internally hollow cylinder 15 which houses inside it pushing means 17, for example a worm screw or auger, adapted to push the molten thermoplastic material towards the cavity 4.

[0052] In addition, the thermoplastic material supply assembly 14 may comprise heating means, for example an electrically powered heating apparatus, adapted to heat the cylinder 15 so as to melt the thermoplastic material present inside it.

[0053] Preferably, the cylinder 15 also comprises a nozzle 18 fluidly connected to the cavity 4, so as to be able to feed the molten thermoplastic material into the latter.

[0054] In particular, the nozzle 18 is preferably fluidly connected to the cavity 4 by means of an injection duct 19.

[0055] More in detail, the injection duct 19 is preferably fluidly connected to the cavity 4 by means of an injection opening 20 formed on a face 8 or 9 of one of the two half-moulds 5 or 6, at the cavity 4.

[0056] In the example shown, the injection opening 20 is formed on the face 8 of the second halfmould 6, that is of the fixed plate, at the cavity 4. In other words, the injection opening 20 is preferably arranged approximately facing the concave portion 7 of the other half-mould 5, that is of the movable plate.

[0057] In addition, machine 1 comprises valve means 21 adapted to selectively bring the thermoplastic material supply assembly 14 into fluid communication with the cavity 4.

[0058] More in detail, the valve means 21 preferably comprise a valve or shutter positioned immediately upstream of the injection opening 17.

[0059] Preferably, the valve means 21 may comprise electronically controlled valves or solenoid valves or solenoid valves.

[0060] With reference to the preferred embodiment of the present invention, machine 1 further comprises a movable slider apparatus 22.

[0061] In use, the movable slider apparatus 22 is adapted to at least partially engage the cavity 4.

[0062] With reference to figure 5, the movable slider apparatus 22 is preferably adapted to engage at least partially the cavity 4 in such a way as to subdivide the same cavity 4 into at least two areas / zones 23a and 23b of complementary shape. The areas 23a and 23b preferably have different thicknesses with respect to each other along the direction di.

[0063] Preferably, the area 23a has a shape complementary to the shape of the first sector 102 of the component 100.

[0064] The area 23b, on the other hand, preferably has a shape complementary to the shape of the opening 101 and / or of the second sector 106 of thickness S2.

[0065] In other words, the movable slider apparatus 22 is preferably adapted to engage the cavity 4 in such a way as to delimit within the latter at least a first chamber 23a of a shape complementary to the shape of the sector 102 of the component 100, i.e. of an annular shape.

[0066] Preferably, the movable slider apparatus 20 is shaped so that the area 23a substantially seamlessly surrounds the area 23b.

[0067] With reference to the example shown, the movable slider apparatus 22 preferably comprises at least one movable slider 24, which is movably carried by a first of the two halfmoulds 5 or 6. In the example shown, the movable slider 24 is carried by the half-mould 5. In addition, the movable slider 24 is preferably facing the concave portion 7 present on the halfmould 6.

[0068] Preferably, the movable slider 24 is slidably movable, along a predetermined sliding direction advantageously parallel to the direction di.

[0069] The sliding direction of the movable slider 24 is preferably also locally orthogonal to the surface 8 or 9 of the second half-mould 5 or 6. Preferably, the movable slider 24 is movable between a first position (figures 1 and 4) and a second position (figures 5 and 6).

[0070] In the first position, the movable slider 24 preferably does not engage the cavity 4. In the second position, the movable slider 24, on the other hand, engages the cavity 4.

[0071] More in detail, in the first position, the free / distal end of the movable slider 24 is preferably arranged flush with / aligned with face 8 or 9 of the respective half-mould 5 or 6, and contributes to forming the same face 8 or 9. More in detail, the free / distal end of the movable slider 24 is preferably shaped in such a way as to form a substantially continuous / homogeneous surface together with face 8 or 9 of the respective half-mould 5 or 6 when the movable slider 24 is in the first position.

[0072] In the second position, on the other hand, the movable slider 24 is preferably adapted to at least partially engage the cavity 4 in such a way as to subdivide the same cavity 4 into the areas / zones 23a and 23b.

[0073] According to one aspect of the present invention, in the second position, the movable slider 24 is preferably adapted to be arranged flush and / or almost in abutment on the second of the two half-moulds 5 or 6, in particular on its face 8 or 9, in such a way as to delimit in the cavity 4 the annular chamber 23a.

[0074] With reference to the preferred embodiment of the present invention, the second half-mould 5 or 6 is preferably provided with a seat 25 of a shape complementary to the movable slider 24. The seat 25, in particular, is preferably arranged facing the movable slider 24.

[0075] In the second position, the movable slider 24 is preferably configured to at least partially engage the seat 25, so as to delimit in the cavity 4 the annular chamber 23a.

[0076] The movable slider 24, in particular, is adapted to be arranged at a predetermined minimum distance from the bottom of the seat 25 when it is arranged in the second position.

[0077] More in detail, in use, the movable slider 24 is preferably adapted to be arranged in contact with the annular edge that delimits the seat 25, that is, which separates the seat 25 from the remaining portion of the face 9 of the half-mould 6, in such a way as to fluidly separate the internal volume of the seat 25 from the remaining volume of the cavity 4, that is, to separate the areas 23a and 23b from each other. This allows in use to separate the molten thermoplastic material present in the cavity 4, that is, in the area 23a, from the molten thermoplastic material possibly present in the seat 25, that is, in the area 23b.

[0078] With reference to the example shown, in particular, the movable slider apparatus 22 preferably comprises a second movable slider 26 of a shape complementary to the shape of the first movable slider 24, which is positioned at the seat 25. The second movable slider 26 is preferably arranged aligned with and facing the first movable slider 24.

[0079] The second movable slider 26 is preferably slidably carried by the second half-mould 5 or 6, that is by the half-mould 5 or 6 opposite to the half-mould carrying the first movable slider 24.

[0080] Preferably, the second movable slider 26 is movable between a first position and a second position. In the first position, the second movable slider 26 is preferably arranged approximately flush with / aligned with face 8 or 9 of the respective half-mould 5 or 6, and contributes to forming the same face 8 or 9.

[0081] In the second position, on the other hand, the second movable slider 26 is preferably arranged set back along its sliding direction with respect to face 8 or 9 of the respective halfmould 5 or 6, so as to delimit the seat 25.

[0082] The second slider 26 is also preferably shaped to contribute to forming the seat 25.

[0083] In use, the first movable slider 24 is adapted to mechanically push the second movable slider 26 into the second position when the same first movable slider 24 is drawn out towards its second position.

[0084] In the respective second positions, the first slider 24 is adapted to be arranged at a predetermined minimum distance from the second slider 25.

[0085] Preferably, in use, a thin film of molten thermoplastic material accumulates between the first movable slider 24 and the second movable slider 26, so that the sliders themselves do not physically come into contact with one another.

[0086] Preferably, the injection opening 20 is made spaced from the movable slider 24, so as to be able to inject the thermoplastic material inside area 21 even when the movable slider is in the second position. When, on the other hand, the movable slider engages the seat 25, it preferably prevents the injection of the thermoplastic material inside area 22.

[0087] With reference to the preferred embodiment, the movable slider apparatus 22 preferably also comprises a movement mechanism 27 adapted to move at least the first movable slider 24 between the first and the second position.

[0088] Preferably, the movement mechanism 27 is a hydraulically driven mechanism.

[0089] For example, the movement mechanism 27 may comprise at least one hydraulically driven actuator 28 coupled to the movable slider 24 and adapted to move the latter between the first and the second position. The actuator 28 can be fluidly connected to the source of pressurised hydraulic fluid 11 of the mould movement mechanism 10. In addition, the movement mechanism 27 of the movable slider 24 may comprise valve means 29 fluidically positioned upstream of the actuator 28 of the same movement mechanism 27 and adapted to control the flow of pressurised hydraulic fluid supplied towards the latter.

[0090] The movement mechanism 27 is also configured to be able to move, on command, the second movable slider 26 at least from its second position towards the first position.

[0091] Machine 1 preferably also comprises an electronic control unit 30, which is operatively connected to at least the movement mechanism 10 of the mould 3, the movement mechanism 27 of the movable slider 24, the valve means 18 and the thermoplastic material supply assembly 11, and is adapted to control their operation according to the method described below.

[0092] In addition, machine 1 may also comprise a user interface, for example a control panel, a touch-sensitive display, a computer and / or the like, which is operatively connected to the electronic control unit 30 and is configured to allow a user to issue commands adapted to pilot the operation of machine 1.

[0093] Preferably, the electronic control unit 30 may be configured to determine when the opening of the valve means 18 is commanded. In addition, following the command to open the valve means 18, the electronic control unit 30 may be configured to command the valve means 29 of the movement mechanism 27 in such a way as to command the withdrawal of the movable slider 24 towards its second position.

[0094] More in detail, following the command to open the valve means 18, the electronic control unit 30 may be configured to invert the control signal of the valve means of the movement mechanism 27, in such a way as to invert the actuation of the actuator of the same movement mechanism 27 and command the withdrawal of the movable slider 24 towards its second position.

[0095] With reference to figures 1 to 6, the method of operation of machine 1 will be described below.

[0096] The method of operation of machine 1 preferably comprises the following steps: a. moving the two half-moulds 5 and 6 towards each other, so as to delimit the cavity 4, and arranging the movable slider 24 in its first position (figure 1), b. controlling the valve means 18 and the thermoplastic material supply assembly 11 in such a way as to inject the thermoplastic material inside the cavity 4 (figure 4) and at least partially fill the cavity 4 itself, c. controlling the movement of the movable slider 24 in such a way as to bring the latter into its second position, in which it engages the cavity 4 (figure 5), d. controlling the valve means 18 and the thermoplastic material supply assembly 11 in such a way as to inject the thermoplastic material inside the cavity 4 (figure 6) and complete the filling of the cavity 4, in particular of area 21.

[0097] In addition, the method further comprises the step of closing the valve means 18 and controlling the mechanism for moving the half-moulds 5 and 6 in such a way as to bring the two half-moulds 5 and 6 into abutment against one another, so as to close the mould 3 and increase the pressure of the thermoplastic material inside the cavity 4.

[0098] The method preferably also comprises the following steps: e. maintaining the movable slider 24 in its second position until the thermoplastic material in the cavity 4 has cooled and solidified, and finally f. controlling the movement mechanism of the half-moulds 5 and 6 in such a way as to space the two half-moulds 5 and 6 and remove the thermoplastic component produced, preferably once solidified.

[0099] Preferably, step a) provides for moving the two half-moulds 5 and 6 close to each other at a distance such as to prevent the free escape of the molten thermoplastic material from the cavity 4, without bringing them completely into abutment against each other.

[0100] Preferably, step b) provides for injecting into the cavity 4 a quantity of material sufficient to fill the portion of the cavity 4 corresponding to the area 23b, so as to prevent the presence of joint lines in the finished thermoplastic component. In other words, step b) preferably provides for injecting into the cavity 4 a quantity of material sufficient to cover the movable slider 24.

[0101] Such filling of the area 23b has the technical effect of preventing the formation of joint lines on the thermoplastic part 100 caused by the solidification of molten / softened thermoplastic material flowing into the cavity 4 around the movable slider 24, from opposite bands of the same, to then join again once past the same movable slider 24.

[0102] Step c), on the other hand, preferably provides for bringing the movable slider 24 into abutment with the annular edge that delimits the seat 25, so as to fluidly separate the internal volume of the seat 25 from the remaining volume of the cavity 4 surrounding the same movable slider 24.

[0103] Consequently, at the end of the solidification phase, the thermoplastic material present in area 23a will be separated from the thermoplastic material present in area 23b, and therefore the resulting thermoplastic component 100 will be provided with the through -opening 101.

[0104] The advantages relating to machine 1 and its method of operation are considerable and evident. The presence of the movable slider apparatus 20, in fact, allows the production of through- openings 101 inside the thermoplastic component 100 during its production, with the evident advantages that this entails.

[0105] Firstly, since the need to perform a cutting operation downstream of the injection moulding operation by means of a hydraulically driven cutting machine separate and distinct from machine 1 is eliminated, the production of the thermoplastic component is much faster and simpler.

[0106] In addition, thanks to the movable slider apparatus 22, it is possible to produce through- openings also in thermoplastic components of high thickness. In particular, it is possible to produce thermoplastic components provided with internal through-openings of considerably greater thickness than the thickness of the thermoplastic components in which the through- openings are made by means of cutting operations.

[0107] In addition, the method described above prevents the creation of joint lines on the resulting thermoplastic component 100.

[0108] Finally, it is clear that modifications and variations may be made to the machine for the production of thermoplastic components by injection moulding and to its method of operation according to the present invention, without however departing from the scope of protection defined by the claims.

[0109] For example, according to a first embodiment, step c) of the method may provide for bringing the movable slider 24 into its second position while keeping it spaced from the facing face 8 or 9 of the second half-mould 5 or 6.

[0110] This allows the production of thermoplastic components 100 having zones of different thickness.

[0111] In particular, this allows for the production of thermoplastic components 100 provided with the first sector 102 of thickness si and the second sector 106 of thickness S2.

[0112] Preferably, by varying the pressure of the hydraulic fluid supplied to the actuator of the movement mechanism 27 of the movable slider 24 during step c), it is possible to vary the thickness S2 of the second sector 106.

[0113] In addition, according to an embodiment illustrated in figures 7, 8 and 9, machine 1 can also be used to produce thermoplastic components 200 provided with a multilayer structure comprising at least two layers 201 and 202 superimposed on each other along a reference axis, and a graphic sheet 203 interposed between the two layers 201 and 202.

[0114] Preferably, at least one of the first layer 201 and the second layer 202 is made of an at least partially transparent thermoplastic material. According to the embodiment illustrated in figures 7 8 and 9, the mould 3 is preferably a rotary table mould, configured to produce multilayer thermoplastic components.

[0115] In particular, the half-mould 6 or movable plate is preferably carried rotatably around a rotation axis R advantageously parallel to the direction di.

[0116] In addition, the two half-moulds 5 and 6 can be shaped to define a plurality of cavities 4, each with a shape complementary to the shape of a respective layer of the multilayer thermoplastic component 200 to be produced.

[0117] In the example shown, in particular, the two half-moulds 5 and 6 can be shaped to define a first cavity 4a of a shape complementary to the first layer 201, and a second cavity 4b of a shape complementary to the multilayer thermoplastic component 200 to be produced.

[0118] According to this embodiment, furthermore, the movement mechanism 27 of the movable slider 24 preferably also comprises a pressure multiplier 30, which is fluidically connected downstream of the valve means 29 of the same movement mechanism 27, and is adapted to locally increase the pressure of the hydraulic fluid supplied to the actuator 28 of the same movement mechanism 27.

[0119] The graphic sheet 203, on the other hand, preferably comprises a component / substrate preferably made of thermoplastic material, for example polymethyl methacrylate (PMMA) or other similar thermoplastic material.

[0120] In addition, the graphic sheet 203 preferably has a lenticular structure. For example, the thickness of the graphic sheet can be between 0.2 and 1 millimetre.

[0121] The graphic sheet 203 is preferably provided with a graphic motif on at least one of its major faces, for example graphic motifs based on ink and / or varnishes.

[0122] In addition, the graphic sheet 203 may advantageously have dimensions and / or a shape complementary to those of the movable slider 24.

[0123] The method for producing the thermoplastic component 200 essentially provides for: g. positioning the graphic sheet 203 inside the cavity 4 of the mould 3, in particular of the first cavity 4a of the mould 3 (figure 9); h. printing the first layer 201 above a first face of the graphic sheet 203 (figure 10), and then i. printing the second layer 202 above the semi-finished product comprising the first layer 201 and the graphic sheet 203, above a second face of the graphic sheet 203 opposite said first face (figures 11 and 12).

[0124] In particular, step h) preferably provides for injecting the thermoplastic material that contributes to forming the first layer 201 into the first cavity 4a, above the graphic sheet 203. Preferably, step g) in turn provides for the steps of rotating the movable half-mould 5 containing the semi-finished product formed by the graphic sheet 203 and the first layer 202 in such a way as to arrange it at the cavity 4b (figure 11), and then injecting the thermoplastic material that contributes to forming the second layer 201 into the second cavity 4b, above the semi-finished product formed by the first layer 201 and the graphic sheet 203 (figure 12).

[0125] In addition, step g) preferably provides for bringing the movable slider 24 into its second position and applying a first pressure level pi on the same movable slider 24. For example, the pressure level pi can be equal to about 200 bar.

[0126] The pressure level pi exerted on the movable slider 24 is multiplied by the pressure multiplier and is preferably greater than the pressure level p2 of the hydraulic fluid that the valve means 29 of the movement mechanism 27 are capable of supplying at the outlet. For example, the pressure level p2 can be equal to about 100 bar.

[0127] In addition, step c) preferably comprises the step of closing the mould 3, i.e., of controlling the movement mechanism of the half-moulds 5 and 6 in such a way as to bring the two halfmoulds 5 and 6 into abutment against one another, so as to close the mould 3 and increase the pressure of the thermoplastic material inside the cavity 4. Simultaneously, step i) preferably provides for reducing the pressure applied on the movable slider 24, for example from the pressure level pi to the pressure level p2.

[0128] This advantageously dampens the pressure profile and the stress exerted on the graphic sheet 203, because the reduction of pressure on the movable slider 24 at least partially compensates for the increase in pressure that occurs during the closing of the mould 3. In particular, this prevents the washing out of the ink present on the graphic sheet 203 and the appearance on the thermoplastic component 200 of optical defects such as, for example, halos, rainbow effects and / or other similar optical defects.

Claims

CLAIMS1.- Machine (1) forthe production of a thermoplastic component (100), said machine (1) comprising:- a mould (3) provided with an internal cavity (4) of a shape complementary to the thermoplastic component (100) to be produced; and- a thermoplastic material supply assembly (14), which is fluidly connected to said cavity (4) through an injection opening (20) and is adapted to inject the molten thermoplastic material that contributes to forming said thermoplastic component in said cavity (4); said mould (3) comprising a first half-mould (5) and a second half-mould (6), which are adapted to be arranged in abutment one on the other and are shaped in such a way as to delimit said cavity (4), wherein at least one of said first half-mould (5) and said second half-mould (6) is carried in a movable manner and is movable to and from the other between said first half-mould (5) and said second half-mould (6), and said machine further comprising a movable slider apparatus (22), which is movably carried by one of said first half-mould (5) and said second half-mould (6), is movable to and from the other between said first half-mould (5) and said second half-mould (6), and is adapted to selectively engage at least a portion of said cavity (4).2.- Machine according to claim 1, wherein said movable slider apparatus (22) comprises a first movable slider (24) which is movably carried by one of said first half-mould (5) and said second half-mould (6) and is movable between a first position and a second position.3.- Machine according to claim 2, wherein in the first position, said first movable slider (24) does not engage said cavity (4) and in the second position said first movable slider at least partially engages said cavity (4).4.- Machine according to claim 3, wherein the other of said first half-mould (5) and said second half-mould (6) is provided with a seat (25) facing the first movable slider (24) and of a shape complementary to the first movable slider (24), in the second position, the first movable slider (24) is configured to at least partially engage said seat (25).5.- Machine according to claim 4, wherein, in the second position, the first movable slider (24) is configured to be in contact with the annular edge that delimits said seat (25), in such a way as to define inside said cavity (4) a chamber (23a) of annular shape which surrounds said first movable slider (24) and is fluidly separated from the volume of said seat (25).6.- Machine according to claim 4 or 5, wherein said movable slider apparatus (22) comprises a second movable slider (26), which is movably carried by the other of said first halfmould (5) and said second half-mould (6), is positioned at the seat (25) and is arranged aligned with and facing the first movable slider (24).7.- Machine according to claim 6, wherein the second movable slider (25) is movable between a third position, in which it is arranged flush with the face (9) of the other of said first half-mould (5) and said second half-mould (6) facing said cavity (4), and a fourth position, in which it is arranged spaced from the face (9) of the other of said first half-mould (5) and said second half-mould (6) facing said cavity (4).8.- Machine according to any one of claims 2 to 7, further comprising valve means (21), which are positioned upstream of said injection opening (20) and are configured to selectively place said supply assembly (14) in fluid communication with said cavity (4).9.- Method for the production of a thermoplastic component (100) by means of a machine (1) made according to claim 8, said method comprising the steps of: a. moving said first half-mould (5) and said second half-mould (6) towards each other in such a way as to delimit the cavity (4), and arranging the first movable slider (24) in said first position, b. controlling the valve means (21) and the thermoplastic material supply assembly (14) in such a way as to inject molten / softened thermoplastic material inside said cavity (4) and at least partially fill the cavity (4) itself, c. controlling the movement of the first movable slider (24) in such a way as to bring the latter into its second position in which it engages the cavity (4), d. controlling the valve means (21) and the thermoplastic material supply assembly (14) in such a way as to inject the molten / softened thermoplastic material inside the cavity (4) and complete the filling of the cavity (4).10.- Method according to claim 9, wherein step b) provides for injecting into the cavity (4) a quantity of molten / softened thermoplastic material sufficient to fill a portion of the cavity (4) positioned at said first movable slider (24).11.- Method for the production of a multilayer thermoplastic component (200) by means of a machine made according to claim 8, wherein said multilayer thermoplastic component (200) comprises a first layer (201), a second layer (202) superimposed on the first layer along a reference axis (A), and a graphic sheet (203) interposed between the first layer (201) and the second layer (202),the method comprising the steps of: e. positioning the graphic sheet (203) inside the cavity (4) of the mould (3); f. printing the first layer (201) above a first face of the graphic sheet (203), and then g. printing the second layer (202) above the semi-finished product comprising the first layer (201) and the graphic sheet (203), above a second face of the graphic sheet (203) opposite to said first face.12.- Method according to claim 11, wherein step g) in turn provides for the steps of: h. injecting into the cavity (4b) the molten / softened thermoplastic material intended to form the second layer (202), i. bringing the movable slider (24) into its second position and applying a first pressure level (pi) on the same movable slider (24), to press the graphic sheet (203) onto the underlying first layer (201), and then j . bringing the first half-mould (5) into abutment against the second half-mould (6) to close the mould (3) and increase the pressure exerted on the material contained in the cavity (4), and simultaneously reducing the pressure applied on the movable slider (24) to a second pressure level (P2) lower than said first pressure level (pi).

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