PRESS FOR FORMING ARTICLES FROM TWO MATERIALS

Abstract

A press 100 for forming workpieces from two materials, comprising a group of molds G comprising a lower mold 1, an upper mold 2 and a middle mold 3, a first drive assembly A which moves the lower mold 1 and / or the upper mold 2, and a second drive assembly B which moves the middle mold 3; wherein the second drive assembly B comprises: a first drive device B1 configured to move the middle mold 3 vertically, a second drive device B2 configured to move the middle mold 3 horizontally, and a third drive device B3 configured to rotate the middle mold 3 about a horizontal transverse axis X.

Description

[0001] The present invention relates to a press for molding workpieces made of two different materials having different colors, different densities, or different hardnesses; in particular, a press for molding shoe elements, for example soles made of polymeric material, and in particular of crosslinkable polymeric material, for example EVA.

[0002] Although specific reference is made below to shoe soles, the press according to the invention can be used to form other types of manufactured workpieces.

[0003] Although specific reference is made below to EVA, the press according to the invention can be used to mold any type of polymer material, such as synthetic rubber, TPU, and the like.

[0004] Although specific reference is made below to two-color workpieces, the press according to the invention can be used to form layered workpieces made of two different materials or of two materials with different hardness or density.

[0005] Although specific reference is made below to injection molding, the press according to the invention can also be used for compression molding.

[0006] Presses for forming two-tone soles are known.

[0007] The Fig. 1 to 4 show a prior art press, generally designated by reference numeral 200. The press 200 includes a group of molds G comprising three elements. The group of molds G includes a lower mold 1, an upper mold 2, and a middle mold 3 configured to be disposed between the lower mold 1 and the upper mold 2.

[0008] The lower mold 1 is mounted on a lower platen 10, which is fixedly mounted on a stationary support. The upper mold 2 is mounted on an upper platen 20, which is designed to slide vertically on columns 40 provided on the stationary support. The upper platen 20 is moved by a first drive assembly A, which generally comprises a toggle mechanism and actuators.

[0009] The middle mold 3 is supported on a carrier 30 which is adjusted by a second drive assembly B comprising an actuator which can adjust horizontally and rotate about a longitudinal axis.

[0010] When reference is made below to an operator standing in front of the press, the term "longitudinal" refers to a direction from the back to the front of the press and the term "transverse" refers to a direction from one side to the other side of the press.

[0011] For design reasons, the middle form 3 may consist of two parts held by corresponding second drive assemblies.

[0012] The molding process includes the following steps: Closing the group of forms G, Injecting a first material into a cavity between the middle mold 3 and the upper mold 2, Injecting a second material into a cavity between the lower mold 1 and the middle mold 3, Opening the group of molds G and removing the middle mold 3 to obtain a first layer of material in the upper mold 2 and a second layer of material in the lower mold 1, Joining the lower mold 1 and the upper mold 2 to place the two material layers that are currently cross-linking on top of each other to obtain a layered workpiece made of two materials, and Opening the lower mold 1 and the upper mold 2 and removing the workpiece consisting of two layer materials.

[0013] The same presses can also be used for single-color compression molding or for compression molding or mixed compression molding, i.e. one injection layer and one compression layer.

[0014] The molding process also includes a cleaning process for upper and lower surfaces 3a, 3b of the middle mold after molding the two material layers, as well as a cleaning process of an upper surface of the lower mold 1 and a lower surface of the upper mold 2 after molding the final product.

[0015] In relation to Fig. 2, during the opening of the group of molds G, i.e., during the lifting of the upper mold 2, the middle mold 3 moves forward toward an operator standing in front of the press 200 and remains on a horizontal plane to allow the operator to clean residues on an upper surface 3a of the middle mold 3 that was connected to the upper mold 2. The lower mold 1 and the upper mold 2 are connected to each other behind the middle mold 3, i.e., the upper mold 2 is lowered.

[0016] As in Fig. 3, the middle mold 3 is rotated laterally by 90° about a horizontal axis extending along one side of the press. This also allows the operator to clean the bottom surface 3b of the middle mold, which was connected to the lower mold 1. The second drive assembly B comprises an actuator connected to the carrier 30 of the middle mold, enabling forward movement of the carrier 30 and rotation of the carrier 30 about a horizontal-axis hinge.

[0017] As in Fig. 4, such lateral rotation of the middle mold 3 not only allows cleaning of the bottom surface 3b of the middle mold, but also leaves a free space in front of the press 200 to allow the operator to remove the formed workpieces when the press is opened.

[0018] With such a molding system, there is no downtime for the cleaning operations of the middle mold 3, which are carried out during the crosslinking step of the polymer material when the first and second molds 1, 2 are connected to each other.

[0019] However, it must be taken into account that during the removal and final cleaning of the lower 1 and upper 2 molds, the middle mold 3 is at the height of the operator's arms and shoulders. During these steps, the operator must work in a confined space near the middle mold 3, which is heated to a temperature of 70°C to 150°C, with the risk of contact with the middle mold 3 and inevitable burns.

[0020] To solve this problem, caused by the burns that the operator may suffer from contact with the central mold, there are presses in which, after the first forming step of the two layers of material, the central mold is adjusted backwards, that is, towards the press injector on the opposite side where the operator is located.

[0021] The advantage of such a press is that the middle mold is not near the operator's arms and shoulders during removal and cleaning of the lower and upper molds, thus avoiding the risk of burns from contact with the middle mold.

[0022] However, such a press has significant drawbacks. In fact, the operator cannot clean the middle mold while the lower and upper molds are coupled together for meshing the final product. To clean the bottom and top of the middle mold, the operator must wait until the lower and upper molds are opened, the formed workpiece is removed, and the middle mold is moved forward between the lower and upper molds.

[0023] With this type of press, it is obvious that the molding cycle takes much longer because the two surfaces of the middle mold cannot be cleaned during the cross-linking step.

[0024] In addition, such cleaning of the middle mold takes place in a small area between the lower and upper molds, which have a temperature of approximately 180°C. Therefore, during cleaning of the middle mold, there is a risk that the operator may touch the lower or upper mold and burn themselves.

[0025] ITPD20120094A1 describes a press for forming two-tone soles according to the preamble of patent claim 1.

[0026] US2016 / 159025A1 describes a press for molding rubber soles, comprising a lower mold, an upper mold, and a middle mold arranged between the lower mold and the upper mold.

[0027] The purpose of the present invention is to eliminate the disadvantages of the prior art by providing a press for forming bimaterial workpieces that is reliable and safe, and can avoid the risk of injury to the operator. Another purpose is to provide such a press for forming bimaterial workpieces that is efficient and can shorten the duration of the forming process.

[0028] These objects are achieved according to the invention by the features of the appended independent claims. Advantageous effects according to the invention result from the dependent claims.

[0029] Further features of the invention will become clearer from the following detailed description, which refers to a purely exemplary and therefore non-limiting embodiment thereof, as illustrated in the accompanying drawings. In the drawings: Fig. 1 - 4 perspective rendering views illustrating a press according to the prior art during the various steps of the forming cycle; Fig. Figure 5 is a perspective view of a press according to the invention when the group of molds is open and the middle mold is arranged in a retracted position between the lower mold and the upper mold; Fig. 5A a detail of Fig. 5, which represents one side of the press; Fig. Figure 6 is a perspective view of a press according to the invention when the group of molds is closed; Fig. Figure 7 is a perspective view of a press according to the invention when the group of molds is open and the central mold is arranged in an extended horizontal position; Fig. Figure 8 is a perspective view of a press according to the invention when the group of molds is closed and the central mold is arranged in an extended horizontal position; Fig. Figure 9 is a perspective view of a press according to the invention when the group of molds is closed and the middle mold is arranged in the extended intermediate position; Fig. 10 is a perspective view of a press according to the invention when the group of molds is closed and the central mold is arranged in the extended, vertically raised position; and Fig. Figure 11 is a perspective view of a press according to the invention when the group of molds is open and the central mold is arranged in an extended, vertically raised position.

[0030] Based on the Fig. 5 to 11, the press according to the invention is described, generally designated by the reference numeral 100. In the following, elements that are identical or correspond to those already described are designated by the same reference numerals, and their more detailed description is omitted.

[0031] As in Fig. As shown in Figure 5, the press 100 comprises a group of molds G comprising a lower mold 1, an upper mold 2, and a middle mold 3. The lower mold 1 has an upper surface 1a with at least one recess consisting of cavities and / or projections corresponding to the lower surface of the workpiece to be produced.

[0032] The upper mold 2 has a bottom surface 2a with at least one recess consisting of cavities and / or projections corresponding to the top surface of the workpiece to be produced. The recess of the lower mold 1 is adapted to be connected to the recess of the upper mold 2 to define a cavity corresponding to the workpiece to be produced.

[0033] The middle mold 3 has an upper surface 3a with at least one recess consisting of cavities and / or projections and can be connected to the recess of the upper mold 2 to define a cavity in which a first layer of the workpiece is formed.

[0034] As in Fig. As shown in Figure 9, the middle mold 3 has a bottom surface 3b with at least one recess consisting of cavities and / or projections, which can be connected to the recess of the lower mold 1 to define a cavity in which a second layer of the workpiece is formed.

[0035] Back to Fig. 5: The press 100 comprises a base 4 from which columns 40 extend. The press 100 generally comprises four columns 40 arranged according to the vertices of a rectangle.

[0036] The lower mold 1 is mounted on a lower platen 10 such that it can slide vertically on the columns 40. A first drive assembly A is provided on the base 4 to adjust the lower platen 10 by means of a vertical translational movement along the columns 40. The first drive assembly A generally comprises a toggle mechanism and actuators.

[0037] The upper mold 2 is arranged on an upper plate 20, which is fixedly arranged on the columns 40. Of course, the upper mold 2 can also be arranged to be movable or adjustable, and the first drive assembly A can also adjust the upper mold 2.

[0038] In any case, the press 100 comprises a first drive assembly A to move the lower mold 1 and / or the upper mold 2 to open / close the mold assembly.

[0039] In particular, balance actuators 11 are provided on the lower platen 10 between the lower platen 10 and the lower mold 1 to push the lower mold 1 upward relative to the lower platen 10.

[0040] As in Fig. As shown in Figure 8, each compensating actuator 11 consists of a cylinder 11a and a piston 11b. The compensating actuators 11 compensate for any height differences between the two lower molds 1, and these are provided in the same press or mold, one on the right side and the other on the left side. Furthermore, the compensating actuators 11 cause the lower mold 1 to perform an upward displacement corresponding to the thickness of the middle mold to close the lower mold 1 below the upper mold 2 when the middle mold 3 has been extended.

[0041] Back to Fig. 5: A heating plate 12 is arranged on the balancing actuators 11 below the lower mold 1 and is in contact with the lower mold 1 to heat it.

[0042] A second drive assembly B is responsible for adjusting the carrier 30 of the middle mold. The second drive assembly B adjusts the middle mold 3 from a first position, in which the middle mold 3 is arranged between the lower mold 1 and the upper mold 2, to a second position in which the middle mold 3 does not block the lower mold 1 and the upper mold 2, so that the lower mold 1 and the upper mold 2 can be connected or coupled to each other.

[0043] The second drive assembly B includes: - a first drive device B1 configured to move the central mold 3 vertically along a vertical axis Z, - a second drive device B2 configured to move the central mold 3 horizontally along a horizontal longitudinal axis Y extending in a longitudinal direction of the press, and - a third drive device B3 configured to rotate the central mold 3 about a horizontal transverse axis X extending in a transverse direction of the press.

[0044] The central mold 3 is provided on a support 30. The support 30 of the central mold is U-shaped and includes two lateral arms 31 that rotate on the outside of the columns 40 so as not to come into contact with the columns 40. Each lateral arm 31 of the support of the central mold is hinged to a carriage or skid 5 via a hinge 50 with a horizontal transverse axis X extending in the transverse direction of the press. The carriages 5 are designed to slide on corresponding horizontal guides 6 with horizontal axes Y1, Y2 extending in the longitudinal direction of the press along the sides of the press. The guide 6 and carriage 5 assembly can be a linear recirculating ball guide.

[0045] The horizontal guides 6 project forward with respect to the front columns 40 arranged in a front part of the press, designed to be oriented towards an operator.

[0046] The horizontal guides 6 are provided to slide vertically on lateral columns 7 arranged laterally on the outside with respect to the columns 40. Generally, each guide 6 is provided on two lateral columns 7. For this purpose, the guide 6, as shown in Fig. 5A, a bracket 60 protrudes laterally outward from the guide. The bracket has two sleeves 61 slidably mounted on the side columns 7.

[0047] The lateral columns 7 are provided on a base support 70 which can be attached to the base 4 of the press.

[0048] According to Fig. 5A includes the second drive assembly B: - the first drive device B1, which moves the horizontal guides 6 in vertical translation on the lateral columns 7 in order to move the central mold 3 vertically along a vertical axis Z, - the second drive assembly B2, which moves the slides 5 in horizontal translation on the horizontal guides 6 in order to move the central mold 3 in horizontal translation along a horizontal longitudinal axis Y, and - the third drive assembly B3, which rotates the support 30 of the central mold about the horizontal transverse axis X of the hinges 50 of the carriages.

[0049] The first drive device B1 may comprise linear actuators arranged between the base support 70 of the lateral columns and the support 60 of each guide 6. Advantageously, the first drive device B1 comprises two intermediate supports 8. Each intermediate support 8 has two sleeves 80 slidably mounted on the lateral columns 7 between the base support 70 and the support 60 of the guide.

[0050] A first actuator 81 is arranged in a central position between the base support 70 and the intermediate bracket 8. The first actuator 81 includes a cylinder attached to the base support 70 and a piston attached to the intermediate bracket 8.

[0051] Two second actuators 82, 83 are arranged between the intermediate bracket 8 and the guide bracket 60 on both sides of the first actuator 81. The second actuators 82, 83 comprise a cylinder attached to the intermediate bracket 8 and a piston attached to the guide bracket 60.

[0052] The second drive device B2 may comprise linear drives comprising a cylinder-piston assembly connected to the guides 6 and slides 5 to adjust the slides on the guides 6.

[0053] The third drive device B3 may comprise an actuator provided on the carriage 5. The actuator of the carriage 5 causes the adjustment of a rack, which engages a gear connected to the carrier 30 of the middle mold. In this way, adjustment of the rack causes rotation of the gear and consequently of the carrier of the middle mold.

[0054] The operation of the press 100 is described below.

[0055] As in Fig. As shown in Figure 5, the group of molds G is open and the middle mold 3 is in the retracted position between the lower mold 1 and the upper mold 2. The cavities of the molds 1, 2, 3 are empty and clean.

[0056] The compensation actuators 11 are in the retracted position.

[0057] At this point, the first drive assembly A is actuated, causing the lower mold 1 to move upwards to close the group of molds G comprising the three molds 1, 2, 3 in a stacked configuration, as shown in Fig. 6 shown.

[0058] Molds 1, 2, 3 were heated to a softening temperature of the polymer material.

[0059] A first polymer material is injected into a first cavity between the top surface 3a of the middle mold and the bottom surface 2a of the upper mold to obtain a first layer.

[0060] A second polymer material is injected into a second cavity between the top surface 1a of the lower mold and the bottom surface 3b of the middle mold to obtain a second layer.

[0061] Instead of the injection molding process, a compression molding process can also be used, in which a polymer material in granular form or a batch with the desired shape can be introduced into the recess of the upper surface 1a of the lower mold and into the recess of the upper surface 3a of the middle mold.

[0062] Once the forming process of the two layers is completed, the first drive assembly A is actuated to move the lower mold 1 downward and open the group of molds G. In such a case, the first layer of polymer material adheres to the upper mold 2 and the second layer of polymer material adheres to the lower mold 1.

[0063] As in Fig. As shown in Figure 7, after the groups of molds G have been opened, the second drive device B2 of the second drive assembly B is actuated and the carriages 5 slide on the horizontal guides 6, causing the support 30 supporting the middle mold 3 to be displaced forward in the horizontal direction. In this way, the middle mold 3 is arranged in an extended horizontal position in which it cannot block the lower mold 1 and the upper mold 2.

[0064] With reference to Fig. 8, the first drive assembly A is operated to move the lower mold 1 upward. The balance actuators 11 are also operated so that the pistons 11b of the balance actuators push the lower mold 1, which is coupled to the upper mold 2, upward, thereby closing the group of molds, which then consists only of the lower mold 1 and the upper mold 2. The two layers of polymer material are superimposed in the cavity between the lower mold 1 and the upper mold 2. The lower and upper molds 1, 2 are heated to a crosslinking temperature so that the two layers are crosslinked to form the final layered product. Such a crosslinking process takes several minutes.

[0065] When the lower and upper molds 1, 2 are closed, the first drive device B1 of the second drive assembly B is actuated to lower the horizontal guides 6 and consequently the middle mold 3 to a minimum height H1 above the ground. In particular, as shown in Fig. 5A, the first actuator 81 of the first drive device B1 is actuated to lower the intermediate bracket 8 onto the side columns 7.

[0066] In view of the above, the central mold 3 is brought to a minimum height H1, for example, to a height of 1 m to 1.4 m above the ground, in order to be more accessible to an operator.

[0067] The operator standing in front of the press 100 can clean the upper surface 3a of the middle mold in complete safety without risking burns. After cleaning the upper surface 3a of the middle mold, the operator can spray a release agent onto the upper surface 3a of the middle mold to ensure that the first layer of polymer material separates from the middle mold and does not adhere to the upper mold 2.

[0068] As in Fig. As shown in Figure 9, after cleaning the upper surface 3a of the middle mold, the first drive device B1 of the second drive assembly is actuated to raise the horizontal guides 6 and thus the middle mold 3 to an intermediate height H2 above the ground. In view of the above, the horizontal guides 6 and the middle mold 3 are raised to an intermediate height H2, for example, to a height of 1.2 m to 1.6 m above the ground.

[0069] In such a case, as in Fig. 5A, the second actuators 82, 83 are actuated to push the bracket 60 of the horizontal guides 6 upwards.

[0070] The third drive device B3 of the second drive assembly is also actuated to rotate the carrier 30 of the middle mold about the axis X of the hinge 50 of the carriage in the direction of the press 100, so that the middle mold 3 is arranged in an extended, vertical intermediate position in which the underside 3b of the middle mold faces the operator standing in front of the press 100.

[0071] Therefore, the operator standing in front of the press 100 can clean the bottom surface 3b of the middle mold in complete safety without risking burns. After cleaning the bottom surface 3b of the middle mold, the operator can spray a release agent onto the bottom surface 3b of the middle mold to ensure that the second layer of polymer material separates from the middle mold and does not adhere to the lower mold 1.

[0072] It should be noted that such cleaning operations of the upper surface 3a and the lower surface 3b of the middle mold are performed during the crosslinking of the two layers of polymer material, when the lower mold 1 and the upper mold 2 are closed. Therefore, such cleaning operations do not extend the molding cycle.

[0073] As in Fig. 10, after completion of the cleaning of the bottom surface 3b of the middle mold, the first drive device B1 of the second drive unit is actuated to raise the horizontal guides 6 and consequently the middle mold 3 to a maximum height H3, which is higher than the height of the bottom surface 2a of the upper mold and higher than the average height of an operator. In such a case, as shown in Fig. 5A, both the first actuator 81 and the second actuators 82, 83 are actuated to lift the intermediate bracket 8 and the bracket 60 of the horizontal guides, respectively.

[0074] In view of the above, the horizontal guides 6 and the middle mold 3 are raised to a maximum height H3, for example 2.3 m to 2.7 m above the ground, in order not to collide with the lower and upper molds 1, 2 or with an operator working in front of the press 100.

[0075] In relation to Fig. 11, after completion of the crosslinking of the polymer layers in the cavity between the lower mold 1 and the upper mold 2, the first drive assembly A is actuated to lower the lower mold 1 and open the group of molds to remove the molded workpiece remaining on the upper surface 1a of the lower mold.

[0076] The operator can then clean the top surface 1a of the lower mold and the bottom surface 2a of the upper mold before starting a new molding cycle. Such a cleaning operation can be performed safely because the middle mold 3 is in an extended, vertical, and raised position, thus out of the operator's way. In other words, there is no danger of the operator touching the middle mold 3 and getting burned.

[0077] Finally, the first drive device B1 of the second drive assembly is actuated to lower the middle mold 3. The third drive device B3 is actuated to rotate the middle mold 3 to a horizontal position.

[0078] The second drive device is actuated to move the middle mold 3 horizontally into a retracted position between the lower mold 1 and the upper mold 2, as shown in Fig. 5 to start a new molding cycle.

[0079] Equivalent variations and modifications may be made to the above-disclosed embodiment of the invention within the knowledge of a person skilled in the art, but still within the scope of the invention as expressed in the appended claims. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] ITPD20120094A1

[0025] US 2016 / 159025A1

[0026]

Claims

A press (100) for forming workpieces from two materials, comprising: a group of molds (G) with a lower mold (1), an upper mold (2), and a middle mold (3); a first drive assembly (A) that moves the lower mold (1) and / or the upper mold (2) to close / open the group of molds; and a second drive assembly (B) that moves the middle mold (3) from a first position, in which the middle mold (3) is arranged between the lower mold (1) and the upper mold (2), to a second position, in which the middle mold (3) does not block the lower mold (1) and the upper mold (2), and thus the lower mold (1) and the upper mold (2) are connected to each other.can be coupled,wherein the second drive assembly (B) comprises:a first drive device (B1) which is suitably configured to vertically adjust the middle mold (3) along a vertical axis (Z), anda second drive device (B2) which is suitably configured to horizontally adjust the middle mold (3) along a horizontal longitudinal axis (Y) which extends in a longitudinal direction of the press,characterized in that the second drive assembly (B) further comprises:a third drive device (B3) which is suitably configured to rotate the middle mold (3) about a horizontal transverse axis (X) which extends in a transverse direction of the press. Press (100) according to claim 1, comprising:lateral columns (7) provided on the sides of the press,horizontal guides (6) suitable for sliding vertically on the lateral columns (7) and extending horizontally in a longitudinal direction of the press,slides (5) suitable for sliding on the horizontal guides (6), anda support (30) carrying the central mold (3) and suitable for rotating on the slides (5) about hinges (50) having the horizontal transverse axis (X) extending in a transverse direction of the press. Press (100) according to claim 2, wherein the first drive assembly (B1) drives the horizontal guides (6) so that they are adjusted vertically; the second drive assembly (B2) drives the carriages (5) so that they are adjusted horizontally; and the third drive assembly (B3) drives the carrier (30) of the middle mold so that it is rotated. Press (100) according to claim 3, wherein the first drive assembly (B1) comprises linear actuators arranged between a base support (70) and a bracket (60) fixedly connected to each horizontal guide (6). Press (100) according to claim 4, comprising two intermediate supports (8) which are suitable for sliding vertically on the lateral columns (7) on the sides of the press, respectively, and wherein the first drive assembly (B1) comprises a first actuator (81) arranged between the base support (70) and the intermediate support (8), and at least one second actuator (82, 83) arranged between the intermediate support (8) and the support (60) which is formed integrally with each horizontal guide (6). Press (100) according to one of claims 3 to 5, wherein the second drive device (B2) comprises linear actuators arranged between the horizontal guides (6) and the carriages (5). Press (100) according to one of claims 3 to 6, wherein the third drive device (B3) comprises a linear drive provided in the carriage (5) to set a rack in translational movement, the rack engaging a gear fixedly connected to the support (30) of the central mold. Press (100) according to one of claims 2 to 7, wherein the lower mold (1) and the upper mold (2) are provided on columns (40) and the support (30) supporting the middle mold (3) is U-shaped and comprises two lateral arms (31) which rotate outside the columns (40) so as not to be hindered by the columns (40); wherein each lateral arm (31) of the support of the middle mold is articulated on a carriage (5). Press (100) according to claim 8, wherein the columns (40) comprise front columns arranged in a front portion of the press adapted to face an operator, and wherein the horizontal guides (6) extend in the longitudinal direction of the press along the sides of the press and project forwardly from the front columns. Press (100) according to one of the preceding claims, comprising balancing actuators (11) arranged between a lower platen (10) and the lower mold (1) to urge the lower mold (1) upwards relative to the lower platen (10). A molding method for a workpiece made of two materials using a press (100) according to any one of the preceding claims, comprising the following steps: closing the group of molds (G) comprising the lower mold (1), the upper mold (2), and the middle mold (3); feeding a first polymer material into a first cavity between the middle mold (3) and the upper mold (2) to form a first layer of a polymer material; feeding a second polymer material into a second cavity between the lower mold (1) and the middle mold (3) to form a second layer of a polymer material; operating the first drive assembly (A) to open the group of molds (G); operating the second drive device (B2) of the second drive assembly to move the middle mold (3) forward and bring it into an extended horizontal position in which it contacts the lower and upper molds (1,2) is not blocked; wherein the first layer remains in the upper mold and the second layer in the lower mold, actuating the first drive assembly (A) to close the lower and upper molds (1, 2) so that the first layer rests on the second layer; heating the lower and upper molds (1, 2) to a crosslinking temperature of the polymeric materials and crosslinking the materials in the lower and upper molds (1, 2) that are bonded together, cleaning an upper surface (3a) of the middle mold during the crosslinking step, actuating the third drive device (B3) of the second drive assembly to rotate the middle mold (3) into a vertical position so that a bottom surface (3b) of the middle mold faces an operator standing in front of the press, cleaning the bottom surface (3b) of the middle mold during the crosslinking step, actuating the first drive device (B1) of the second drive assembly,to move the middle mold (3) upwards to an extended, vertical and raised position in which it is located above a bottom surface (2b) of the upper mold and above an average height of an operator, and actuating the first drive assembly (A) to open the first and second molds (1, 2) and withdraw the molded workpiece.

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