WO2021111268A1

WO2021111268A1 - Moulding method and apparatus

Info

Publication number: WO2021111268A1
Application number: PCT/IB2020/061233
Authority: WO
Inventors: Davide Penazzi; Stefano Bergami; Riccardo PIANCASTELLI
Original assignee: Sacmi Cooperativa Meccanici Imola Societa' Cooperativa
Priority date: 2019-12-05
Filing date: 2020-11-27
Publication date: 2021-06-10
Also published as: CN114423580A; EP4028234A1; IT201900023139A1; TW202128389A

Abstract

A compression moulding method and apparatus are described, wherein a dose of plastics is deposited on a bottom portion of a first lower half-mould where the dose is laterally contained by lateral containment means comprising at least three elongated elements projecting from the bottom and arranged along a circumference, afterwards the dose is compression-moulded between the first half-mould and one second upper half-mould, with the lateral containment means entering the bottom of the first half-mould, by a retractable sliding movement, such to allow compressing the dose.

Description

MOULDING METHOD AND APPARATUS

Background of the invention

[0001] The invention relates to a compression moulding method and apparatus, in particular for moulding doses of plastics.

[0002] Specifically, though not exclusively, the invention may be used for moulding flat-shaped items (for example disc-shaped), in particular items with a relatively small thickness and weight, made of plastics and which can be used, for instance, as gaskets inside capsules for closing containers (such as metal capsules).

[0003] Patent Publication US 2004/130068 A1 discloses a compression mould wherein one dose of plastics is firstly deposited on a support formed by three pins defining three base points for the dose, at a certain distance from a bottom of a female half-mould, and which is then released on the bottom of the female half-mould, just before or at the beginning of the compression, by virtue of the fact that the pins are sliding and can sink penetrating inside the bottom.

[0004] Each of the patent publications EP 2 889 116 Al, US 2010/084788 A1 and US 2011/018166 Al discloses the preamble of claim 1.

[0005] The prior art related to compression moulding of at least a dose of plastics has the problem of ensuring the precise and correct positioning of the dose into the mould before compressing it, allowing at the same time, a relatively high productivity,

Summary of the invention

[0006] An object of the invention is to provide a method and/or an apparatus capable of solving the aforesaid problem of the prior art.

[0007] An object is to provide an alternative solution to the problem of depositing a dose of plastics in a compression mould.

[0008] An object is to allow depositing a dose of plastics in a compression mould rapidly and with a precise positioning.

[0009] An advantage is to deposit the dose of a plastics in a desired position in a reliable and regular way.

[0010] An advantage is to make an apparatus that is of easy and simple construction for compression moulding of plastics.

[0011] An advantage is to allow a simple and safe transfer of the moulded product from the mould where compression takes place towards the zone/s where the product can be further processed. [0012] An advantage is to guarantee, after opening the compression mould, an easy handling of the moulded item, which can be held and moved by one of the half-moulds forming the mould itself.

[0013] An advantage is to ensure the transfer of the moulded product exiting the compression mould even in case of a particularly light product and/or with a relatively small thickness.

[0014] Such objects and advantages and others are obtained by a method and/or apparatus according to one or more of the below reported claims.

[0015] In an example, a moulding method comprises the steps of depositing at least one dose of plastics on a bottom portion of a first half-mould, wherein the dose deposited on the bottom portion is contained laterally by lateral containment means projecting from the bottom, and moulding the dose between the first half-mould and a second half-mould, wherein the lateral containment means enters the bottom of the first half-mould, for instance by a retractable sliding movement, so as to allow the compression of the dose. [0016] When the lateral containment means is in the protruding position in which it projects from the bottom of the first half-mould, it may be configured such as to operate as stop means which, when the dose is deposited on the bottom of the first half-mould, stops a movement of the dose on the bottom caused by an inertial force applied to the dose. Such movement may, in particular, have at least one motion component in a direction parallel to the bottom of the first half-mould. Such inertial force may comprise, in particular, a centrifugal force caused by a rotation movement carried out by the dose while being deposited on the bottom of the first half-mould.

Brief description of the drawings [0017] The invention shall be better understood and implemented with reference to the enclosed drawings showing some non-limiting embodiments, wherein:

Figures 1A to IE are five sections showing five steps in sequence of a compression moulding method according to the present invention;

Figure 2 shows an enlarged detail of Figure 1A wherein a part of the lower half mould of the compression mould is represented;

Figure 3 shows an enlarged detail of Figure 1A wherein a part of the upper half mould of the compression mould is represented;

Figure 4 shows an enlarged detail of Figure 1C including the compression forming zone of the dose; Figure 5 shows an enlarged detail of Figure 1C including the compression forming zone of the dose;

Figure 6 shows an enlarged detail of Figure ID wherein a part of the lower half mould of the compression mould is represented;

Figure 7 shows an enlarged detail of Figure ID wherein a part of the upper half mould of the compression mould is represented;

Figure 8 shows an enlarged detail of Figure IE wherein a part of the upper half mould of the compression mould is represented;

Figure 9 shows the moulded product obtained by the compression moulding method of the Figures 1A to IE;

Figure 10 shows some examples of moulded products obtainable by a compression moulding method according to the present invention;

Figure 11 is a plan schematic view from above of a moulding plant with an insertion carousel which inserts doses into a moulding carousel including the moulding apparatus of Figures 1A to IE;

Figure 12 is a vertical elevation side view, partially sectioned, of a conveyor device which transfers the moulded products from the moulding carousel of Figure 11 to a zone where they can be further processed;

Figure 13 is a plan view from above of the conveyor device of Figure 12.

Detailed description

[0018] Referring to the enclosed drawings, a compression moulding apparatus, suitable, in particular, for moulding doses of plastics has been indicated as a whole by a 1. The moulding apparatus 1 may be used, in particular for moulding flat-shaped items (with a relatively small thickness and/or particularly light), such as disc-shaped items, made of plastics and usable, as in the specific example, as gaskets inside capsules for closing containers (for instance metal capsules).

[0019] The moulding apparatus 1 may comprise, in particular, at least one compression mould with at least one first half-mould 2 and at least one second half-mould 3 cooperating between them to define a forming cavity for the compression moulding of at least one dose D of plastics. In particular, the first half-mould 2 and the second half-mould 3 may comprise, respectively, a lower half-mould and an upper half-mould. In particular, the first half-mould 2 and the second half-mould 3 may comprise, respectively, at least one die and one punch cooperating between them. [0020] The moulding apparatus 1 may comprise, in particular, means for depositing at least one dose of plastics in the first half-mould 2 such that the dose is later compressed in a forming cavity defined between the first half-mould 2 and the second half-mould 3 in the closed mould configuration (see Figure 5). Means for depositing may comprise, in particular, means for extruding plastics, such as an extruding nozzle, provided with separating means (for instance a movable element which periodically opens and closes the extruding nozzle) configured to separate doses of plastics from the extruder flow of plastics. The means for depositing may comprise, for example, extruding means of the known type and/or separating means of the known type.

[0021] The means for depositing may comprise, in particular (see Figure 10), an insertion carousel A which can rotate about a vertical rotation axis and which comprises a plurality of pick-up devices (arranged on the insertion carousel A angularly spaced-apart from each other and with a circumferential trajectory indicated in the figure schematically by a) each of which picks up a dose of material from the extruding means to leave it later to the compression moulding means. The compression moulding means may comprise, in particular, a moulding carousel B which can rotate about a vertical rotation axis and which comprises a plurality of moulding apparatuses 1 (arranged on the moulding carousel angularly spaced apart from each other and with a circumferential trajectory indicated in the figure schematically by b) each of which comprises a first half-mould 2 and a second half-mould 3. The pick-up devices of the insertion carousel A are configured to release and insert doses of plastics into the moulding apparatuses 1 of the moulding carousel B.

[0022] Each moulding apparatus 1 may comprise, in particular, lateral containment means 4 configured to assume at least one protruding position (see Figures 2, 4 and 6) wherein it projects out of a bottom 5 of the first half-mould 2 such to delimit a bottom portion, and at least one recessed position (see Figure 5) wherein it enters the bottom 5 such to allow the compression of the dose D on the bottom 5 lowerly delimiting the forming cavity. The lateral containment means 4 may be configured, in particular, to assume at least one protruding position in which it projects out of a bottom 5 of the first half-mould 2 and is located internally at a distance from a perimeter edge of the bottom 5 itself, where this distance is considered in a direction transverse to a direction of projection of the lateral containment means 4. The lateral containment means 4, in a protruding position, may be, in particular, distant from a centre of the bottom. The lateral containment means 4, in a protruding position, may be, in particular, distant from a periphery of the bottom. In particular, the lateral containment means 4, in a protruding position, may emerge in height both from a central bottom portion and from a peripheral bottom portion. The lateral containment means 4, in the protruding position in which it protrudes from the bottom 5, is arranged above the bottom 5 itself (internally to this bottom).

[0023] The lateral containment means 4 may comprise, in particular, at least one, or two, or more than two elongated elements extended along a longitudinal direction (parallel to the mould axis and/or the direction of opening and closure of the half-moulds, as in this example). The elongated elements may be, in particular, spaced-apart from each other such to delimit the bottom portion on which the dose D is deposited. The elongated elements may be in particular, parallel between them. A maximum size of the dose D deposited by the means for depositing, considered in a direction transversal to the longitudinal direction of the elongated elements, may be, in particular (see Figure 2) lower than a minimum distance between the elongated elements, such that the dose deposited on the bottom portion is arranged between the elongated elements. In other examples (see Figure 11), a maximum dimension of the dose D deposited by means for depositing, considered in a direction transversal to the longitudinal direction of the elongated elements, may be in particular, higher than a minimum distance between two elongated elements, so that the dose, deposited on the bottom portion and possibly urged to move on the bottom due to an inertial force, is stopped by two elongated elements.

[0024] The elongated elements may be arranged on the bottom 5 so that, when they are in a protruding position, at least one or at least two of the elongated elements may serve as means for stopping a motion of the dose D which, once deposited on the bottom 5, may undergo inertial forces which tend to move it according to a motion direction at least partially parallel to the bottom 5.

[0025] The lateral containment means 4 may comprise, in particular, at least three elongated elements (parallel between each other) arranged circumferentially (as in the example of Figures 1A to IE), thereby the dose D deposited on the bottom portion may be surrounded by the set of the elongated elements. The lateral containment means 4 may comprise, in particular, elongated elements arranged angularly equally spaced apart from each other.

[0026] In other examples, the lateral containment means 4 may comprise, in particular, only two elongated elements, or four or more elongated elements, for instance arranged along a circumference with a diameter which is higher that the diameter of the dose D so that the dose D can be deposited on the bottom of the forming cavity and be therein contained laterally by the elongated elements.

[0027] The lateral containment means 4 may comprise, in particular (see Figure 11), at least one or at least two elongated elements (for instance parallel between them) arranged in a de-centered or asymmetric way with respect to the centre of the axis of the compression mould, in order to form lateral abutment or stop means contrasting a movement of the dose D inside the forming cavity.

[0028] Such movement may be produced, in particular, by a combination of forces which are generated on the dose, for instance due to the dynamics and kinematics of the various devices with which the dose interacts.

[0029] Among these forces it can be mentioned, in a non-limiting way, the centrifugal force produced by the carousel for transporting or inserting the dose and/or the force whereby the dose is transferred by the carousel for transporting or inserting to the forming cavity in the moulding carousel and/or the adhesion forces exerted by the dose on all the surfaces it is put in contact with and/or the centrifugal force produced by the moulding carousel and/or the elastic forces accumulated by the dose, etcetera.

[0030] The combination of one or more of these forces and/or of other possible forces will produce on the dose at least a direction of prevailing motion which will be hindered by the lateral contrast or lateral stop means which, as seen, may comprise, in particular, at least one, or at least two elongated elements. The lateral contrast or stop means is configured such as to stop the motion of the dose D, in particular on the bottom 5 (i.e. in a direction substantially parallel to the bottom 5), due to the combination of forces operating on the dose D.

[0031] With reference to the example of Figure 11, the lateral containment means 4 comprises two elongated elements arranged at a mutually angular distance (where the vertex of the angle may be a geometric centre of the forming cavity) which is lower than 180°, or lower than 90°, or lower than 60°.

[0032] The elongated elements, in this case, stop laterally the dose D which is positioned by the insertion carousel A on the bottom 5 with a resulting force F acting on the dose D, so that the elongated elements are arranged on the bottom 5 of the forming cavity as de-centred towards the direction of the resulting force F, to stop the dose D motion on the bottom 5, a motion which may comprise, as in the specific example, at least a radial component and at least a tangential component. The two elongated elements may be arranged, in particular, on the bottom 5 of the forming cavity of the moulding carousel B, one beside the other to form a barrier obliquely arranged which is opposed to a movement of the dose D with at least a radial component and at least a tangential component.

[0033] In these specific examples, the lateral containment means 4 comprises elongated elements in form of pins or poles. In other examples, not shown, the lateral containment means may comprise, in particular, one, or two, or three or more than three, elongated elements in shapes different from a pin, for example in the shape of flat plates, or of circular sections, or pairs of walls joined at an angle, etcetera.

[0034] The lateral containment means 4 may be conformed, as in the herein illustrated specific example, such to perform a retractable movement inside the bottom 5 of the first half-mould 2, in particular by an axial sliding inside sliding holes arranged on the bottom 5 of the first half mould 2.

[0035] The lateral containment means 4 may be, in particular, supported by a support element 6 axially sliding and arranged below the bottom 5 of the first half-mould 2 which lowerly delimits the compression forming cavity.

[0036] The lateral containment means 4 may be, in particular, fixed to an annular portion 7 of the first half-mould 2 surrounding the bottom 5 of the first half-mould 2 and which can axially slide in a direction parallel to the opening and closing direction of the mould formed by the first half-mould 2 and by the second half-mould 3. The annular portion 7 may be fixed, as in this example, to the support element 6 of the lateral containment means 4. During the step of closing the mould (see Figures 4 and 5), the sliding annular portion 7 of the first half-mould 2 interacts in contact with an annular portion 8 of the second half-mould 3, thereby the sliding annular portion 7 of the first half mould 2 may slide downwards with respect to the bottom 5 of the first half-mould 2 (with reference to Figures 4 and 5), so that the lateral containment means 4 may perform the retractable movement in which they sink below the bottom 5 of the first mould 2, penetrating into the bottom 5 itself and leaving the forming cavity for the compression of the dose D free.

[0037] The first half-mould 2 may comprise, in particular, elastic means 9 (for instance arranged between the sliding annular portion 7 of the first half-mould 2 and a support portion 10) configured to exert a force contrasting the retractable movement, i.e. a force which tends to move the lateral containment means 4 towards the protruding position (in this case upwards).

[0038] The means for depositing the dose D of plastics is configured to deposit the dose D on the bottom portion (see Figure 2 or Figure 11) so that the dose D deposited on the bottom portion is laterally contained, and is thus held in the desired position, by the lateral containment means 4.

[0039] The lateral containment means 4 may be, in particular, configured to assume the protruding position when the depositing means deposit the dose D on the bottom portion so that the dose D deposited on the bottom portion is laterally contained by the lateral containment means 4, and to assume the recessed position when the dose D is compressed.

[0040] The lateral containment means 4 may comprise, in particular, two elongated elements arranged one beside the other, at a distance lower than a transversal dimension of the dose D, to form a barrier opposed to the force F applied to the dose D (a force which, as said, may result from more forces operating on the dose D) and which tends to move the dose D on the bottom 5. In the specific example (Figure 11), wherein an insertion carousel A transfers the dose D to a moulding carousel B, the two elongated elements are arranged as de-centered both with respect to the circumferential trajectories of the carousels A and B and with respect to the radial direction of the moulding carousel B.

[0041] The forming cavity may be, in particular, conformed such that the moulded product G (see Figures 7 to 9) comprises at least one undercut surface 11, where “undercut” is intended with reference to a mould opening and/or closing direction. The undercut surface 11 may be, in particular, engaged with at least one counter-surface of the second half-mould 3. In particular, the moulded product G may comprise at least one lateral protrusion and/or at least one lateral recess of the undercut surface 11 and which is formed by at least one corresponding recess and/or at least one corresponding protrusion of the second half-mould 3.

[0042] The undercut surface 11 may be configured, in particular, such that, when the first and the second half-mould 2 and 3 are moved away from each other in the mould opening direction, the moulded product G remains engaged with the second half-mould 3 (see Figure 7). The undercut surface 11 may be, in particular, arranged on a peripheral edge of the moulded product G.

[0043] The forming cavity may be, in particular, conformed such that the moulded product G comprises a second surface opposed and substantially symmetrical to the undercut surface 11, where “symmetrical” is intended with reference to a plane orthogonal to the mould opening and/or closing direction. The undercut surface 11 and the aforesaid second surface, opposed to the undercut surface 11, may comprise, in particular, two tapered surfaces (for example truncated cone) with inclinations opposite to each other. [0044] In the specific example herein described, the lateral containment means 4 assumes a recessed position by means of an axial sliding, in particular through holes made on the bottom 5 of the first half-mould. It is possible to envisage, in other non-illustrated examples, lateral containment means capable of assuming a recessed position by other types of movements (such as a rotation or a combined movement of translation and rotation) and/or capable of assuming a retractable recessed position, for instance lateral containment means capable of retreating into a housing on the bottom of the forming cavity.

[0045] The moulding apparatus 1 may implement, by its operation, a compression moulding method which may comprise, in particular, the step of positioning the lateral containment means 4 in a protruding position (Figure 6) wherein the lateral containment means 4 projects from the bottom 5 of the first half-mould 2 such to delimit a portion of the bottom of the first half-mould 2.

[0046] The compression moulding method may comprise, in particular, the step of depositing at least one dose D of plastics on the aforesaid bottom portion, when the lateral containment means 4 is in a protruding position (Figure 2 or Figure 11), so that the dose D deposited on the bottom portion is laterally contained by the lateral containment means 4 and held on the bottom portion.

[0047] In particular, the dose D deposited on the aforesaid bottom portion may be arranged inside a delimited space by the lateral containment means 4 (arranged between or surrounded by, the elongated elements) and/or the dose D may be laterally stopped by the lateral containment means 4 operating as stop means.

[0048] The compression moulding method may comprise, in particular, after the step of depositing the dose D on the bottom 5, the step of positioning the lateral containment means 4 in a recessed position wherein the lateral containment means 4 enters the bottom 5 of the first half-mould so as to allow the compression of the dose. Figure 4 shows the annular portion 7 of the first half-mould 2 interacting in contact with the annular portion 8 of the second half-mould 3, which determines the retractable movement of the lateral containment means 4 from the protruding position (Figure 4) to the recessed position (Figure 5).

[0049] The compression moulding method may comprise, in particular, the step of moulding the dose D in the forming cavity defined between the first half-mould 2 and the second half-mould 3 (Figure 5), with the lateral containment means 4 in a recessed position, to obtain a moulded product G.

[0050] When the first half-mould 2 and the second half-mould 3 are in a closed position (Figure 5), wherein the dose D is compressed in the forming cavity to form the moulded product G, the lateral containment means 4 is in a recessed position thereby, substantially, the upper end of the lateral containment means 4 is very close to the bottom surface 5 of the first half-mould 2, i.e. with the lower surface of the forming cavity, such to provide continuity on the bottom 5 and not interfering negatively with the forming.

[0051] The compression moulding method may comprise, in particular, after the step of moulding, the step of opening the mould (Figure 6 related to the first half-mould 2 and Figure 7 related to the second half-mould 3), i.e. moving the first and the second half mould 2 and 3 away from each other in the mould opening direction. It is possible to provide, in particular, that, during the step of moving away, the moulded product G remains engaged to the second half-mould 3 (Figure 7), by virtue of the fact that the moulded product G comprises the undercut surface 11 engaged with the counter-surface of the second half-mould 3. As said, the undercut surface 11 may be arranged on a peripheral edge of the moulded product G, even if other positions are possible.

[0052] The compression moulding method may comprise, in particular, after the step of opening the mould, or moving the half-moulds 2 and 3 away from each other, the step of expelling the moulded product G from the second half-mould 3 by means of a detachment force capable of disengaging the undercut surface 11.

[0053] Such detachment force may be generated, in particular, by a relative movement between two portions of the second half-mould 3, in particular of the annular portion 8 and of a central portion 12 (see passage from Figure 7 to Figure 8), where the central portion 12 may comprise, in particular, a punch portion with a surface transversal to the mould axis and which compresses the material during the moulding step. In practice, in the specific example, the aforesaid relative movement is carried out by a descent movement of the central portion 12. [0054] Such detachment force may be generated, in particular, in addition or in alternative to the aforesaid relative movement between the annular portion 8 and the central portion 12 of the second half-mould 3, from a fluid jet directed to the moulded product G, for example a compressed air jet which is let pass through a circuit arranged in the second half-mould 3 and ending with outlet means arranged on a wall of the second half-mould 3 which, when the mould is closed, delimits the forming cavity. In particular, such outlet means may further have the function of a vent of the forming cavity.

[0055] Such outlet and/or vent means may comprise, in particular, at least one interspace (annular-shaped) made on an outer surface of the central portion 12 or punch portion (for example an interspace between the central portion 12 and the annular portion 8). Such outlet and/or vent interspace may have, in particular, a dimension equal to or lower than 0.02 millimetres.

[0056] As said, the moulded product G may comprise a second surface opposite and similar to the undercut surface 11, where the undercut surface 11 and the second opposite surface may comprise, in particular, two tapered surfaces, for example truncated cones, with inclinations opposite to each other (see, for example, Figure 9), such to provide a certain overall symmetrical feature of the moulded product G. The two tapered surfaces may be convex, such as in the example of Figure 9.

[0057] In Figure 10 six different examples of moulded products G that can be made are shown, wherein, from the top of Figure 10 downwards, the peripheral edge of the moulded product G comprises: (i) a series of alternating elevations and hollows, such as an indentation or knurling, (ii) an annular notch with symmetrical and rounded edges, (iii) two convex truncated-cone surfaces on a disc-shaped moulded product which is not plane but curved, (iv) two concave truncated-cone surfaces, (v) a median annular protrusion, (vi) a median annular recess.

[0058] The moulding apparatus 1 may comprise, in particular, a conveyor device for conveying the moulded product G from the compression mould to the following operative zone/s. The conveyor device may comprise, in particular (see Figures 12 and 13), a first transfer carousel 13 which rotates about a vertical rotation axis and which picks up the moulded products G released by the moulding apparatus 1. The first transfer carousel 13 may be provided, in particular, with first holding and suction means which hold the moulded product G by a suction pressure. In the specific example, the moulded product G is released by the moulding apparatus 1 in a direction from above downwards and the first suction holding means generates a suction pressure on the lower side of the moulded product G. The first suction holding means may comprise, in particular, at least one body

14 which has a plurality of apertures or holes (arranged angularly spaced apart on the first transfer carousel 13) connected to vacuum generating means by means of a fluid circuit at least partially internal to the first transfer carousel 13 to generate a suction pressure on the plane whereon the moulded product G (released by the moulding apparatus 1) is laid. In particular, the apertures or holes on the body 14 may be put in communication with vacuum generating means each time limited to the concerned angular sector.

[0059] The conveyor device may comprise, in particular, a second transfer carousel 15 which rotates about a vertical rotation axis and which picks up the moulded products G released by the first transfer carousel 13. The second transfer carousel 15 may be provided, in particular, with second holding and suction means which holds the moulded product G by a suction pressure. In the specific example, the moulded product G is left by the first transfer carousel 13 with a direction from the bottom upwards and the second suction holding means generates a suction pressure on the upper side of the moulded product G. The second suction holding means may be configured, in particular, to hold the moulded product G from above, i.e. on the upper side thereof. In particular, the second suction holding means comprises a body 16 which has a plurality of apertures or holes (arranged angularly spaced apart on the second transfer carousel 15) connected to vacuum generating means by a fluid circuit at least partially internal to the transfer carousel 15 to generate a suction pressure on the upper side of the moulded product G. In particular, the apertures or holes on the body 16 may be put in communication with vacuum generating means each time limited to the concerned angular sector.

[0060] The conveyor device may comprise, in particular, a suction conveyor 17 (for instance linear) which picks up the moulded products G from the second transfer carousel 15. In the specific example, the moulded product G is left by the second transfer carousel

15 in a direction from above downwards and the suction conveyor 17 generates a suction pressure on the lower side of the moulded product G. The conveyor 17 may comprise, for example, a suction conveyor belt which generates a suction pressure on the lower side of the moulded products G.

Claims

1. Compression moulding method, comprising the steps of: providing a compression mould comprising at least one first half-mould (2) and at least one second half-mould (3); positioning lateral containment means (4) in a protruding position in which it projects from a bottom (5) of said first half-mould (2); depositing at least one dose (D) of plastics on said bottom (5), with the lateral containment means (4) in a protruding position, so that the dose (D) deposited on said bottom (5) is at least partly laterally contained by said lateral containment means (4); moulding the dose (D) in a forming cavity between the first half-mould (2) and the second half-mould (3) to obtain a moulded product (G); characterized by comprising, after the step of depositing, the step of positioning the lateral containment means (4) in a recessed position in which it enters the bottom (5) of said first half-mould (2) so as to allow the compression of the dose (D), said step of moulding the dose (D) being performed with the lateral containment means (4) in the recessed position.

2. Method according to claim 1, wherein said lateral containment means (4) comprises a plurality of elongated elements extending in a longitudinal direction, spaced apart from each other.

3. Method according to claim 1 or 2, wherein said lateral containment means (4), in the protruding position, stops a movement of said dose (D) on which operates a force which tends to move said dose (D) on said bottom (5).

4. Method according to claim 3, wherein said lateral containment means (4) comprises at least two elongated elements which, in the protruding position, cooperate to stop said movement of said dose (D) in a direction at least partly parallel to said bottom

(5).

5. Method according to claim 4, wherein said two elongated elements are arranged one beside the other to form a barrier opposed to the force which tends to move said dose (D) on said bottom (5).

6. Method according to any one of the preceding claims, wherein said lateral containment means (4) comprises at least three elongated elements arranged in a circumferential manner, so that the dose (D) deposited on said bottom (5) is surrounded by said elongated elements.

7. Method according to any one of the preceding claims, wherein said step of positioning the lateral containment means (4) in a recessed position comprises a movement in which said lateral containment means (4) sinks below said bottom (5) penetrating into the bottom itself.

8. Method according to any one of the preceding claims, comprising, after the moulding step, the step of moving away the first and second half-moulds (2 and 3) from each other in a mould opening direction, in which, during the step of moving away, the moulded product (G) remains engaged to the second half-mould (3) since the moulded product (G) comprises at least one undercut surface (11), where “undercut” is intended with reference to the mould opening direction, which is engaged with at least one counter-surface of the second half-mould (3).

9. Method according to claim 8, wherein the undercut surface (11) is arranged on a peripheral edge of the moulded product (G).

10. Method according to claim 8 or 9, comprising, after the step of moving away, the step of expelling the moulded product (G) from the second half-mould (3) by means of a detachment force capable of disengaging the undercut surface (11), in which the detachment force is generated by a relative movement between an annular portion (8) and a central portion (12) of the second half-mould (3) and/or by a fluid jet directed onto the moulded product (3).

11. Method according to any one of claims 8 to 10, wherein the moulded product (G) comprises a second surface which is opposite and substantially symmetrical to the undercut surface (11), where “symmetrical” is intended with reference to a plane orthogonal to the mould opening direction.

12. Method according to claim 11, wherein the undercut surface (11) and the second surface comprise two tapered surfaces, for example truncated cones, with inclinations opposite to each other.

13. Method according to any one of the preceding claims, comprising, after the step of moulding the dose (D) to obtain a moulded product (G), the steps of: transferring the moulded product (G) from said compression mould to first suction conveyor means (13) which generates a suction pressure on a lower side of the moulded product (G); transferring the moulded product (G) from said first suction conveyor means (13) to second suction conveyor means (15) which generates a suction pressure on an upper side of the moulded product (G); and transferring the moulded product (G) from said second suction conveyor means (15) to third suction conveyor means (17) which generates a suction pressure on the lower side of the moulded product (G).

14. Compression moulding apparatus (1), comprising: at least one first half-mould (2) and at least one second half-mould (3) cooperating with each other to define a forming cavity for the compression moulding of at least one dose (D) of plastics; lateral containment means (4) configured to take at least one protruding position, in which it protrudes from a bottom (5) of said first half-mould (2), and at least one recessed position, in which it enters said bottom (5) to allow the compression of the dose (D) on said bottom (5); means for depositing at least one dose (D) of plastics on said bottom (5) so that the dose (D) is subsequently compressed in the forming cavity between the first half-mould (2) and the second half-mould (3); said lateral containment means (4) being configured to take the protruding position when said means for depositing deposits the dose (D) on said bottom (5) so that the dose (D) deposited on said bottom (5) is contained laterally by said lateral containment means (4), and to take the recessed position when the dose (D) is compressed.

15. Apparatus according to claim 14, wherein said lateral containment means (4) comprises a plurality of elongated elements extending in a longitudinal direction, spaced apart from one another; said plurality comprising, in particular, at least three elongated circumferentially arranged elements, whereby the dose (D) deposited on said bottom (5) is surrounded by said elongated elements.

16. Apparatus according to claim 15, wherein a maximum dimension of the dose (D) deposited by said means for depositing, considered in a direction transverse to said longitudinal direction, is less than a minimum distance between said elongated elements, so that the dose (D) deposited on said bottom (5) is arranged between said elongated elements.

17. Apparatus according to any one of claims 14 to 16, wherein said forming cavity is configured so that the moulded product (G) comprises at least one undercut surface (11), where “undercut” is intended with reference to a mould opening direction, engaged with at least one counter- surface of the second half-mould (3), so that, when the first half-mould (2) and the second half-mould (3) are moved away from each other in the mould opening direction, the moulded product (G) remains engaged with the second half-mould (3); said undercut surface (11) being, in particular, arranged on a peripheral edge of the moulded product (G).

18. Apparatus according to any one of claims 14 to 17, wherein said lateral containment means (4) is configured so as to be able to perform a retractable movement inside said bottom (5).

19. Apparatus according to any one of claims 14 to 18, wherein said lateral containment means (4) is configured so as to assume the retracting position by means of an axial sliding through one or more holes made in said bottom (5).

20. Apparatus according to any one of claims 14 to 19, combined with a transport device comprising: first suction conveyor means (13) which generates a suction pressure on a lower side of the moulded product (G) and which is configured to receive the moulded product (G) from the compression mould of said apparatus; second suction conveyor means (15) which generates a suction pressure on an upper side of the moulded product (G) and which is configured to receive the moulded product (G) from said first suction conveyor means (13); and third suction conveyor means (17) which generates a suction pressure on the lower side of the moulded product (G) and which is configured to receive the moulded product (G) from said second suction conveyor means (15).