Hot press and method for vacuum curing of vehicle tires in a hot press

Abstract

A hot press (1) for vulcanizing vehicle tires under vacuum conditions, - the hot press has an upper part (3) and a lower part (6), wherein a container (2) with molded parts (14, 16, 17, 18, 21) having segmented vulcanizing molds and a columnar upper cover (4) surrounding the container are arranged on the upper part (3); - wherein the upper cover (4) is fixedly arranged on the upper part (3); - wherein the diameter of the upper cover (4) is determined such that the upper cover can slide over the lower part (6) with a small clearance, and the length (23) of the upper part is sufficient to allow While the vulcanizing mold is still open, a closed inner space (12) of the cover is formed by the lower part (6) and the upper part (4) of the hot press; - wherein in the first stroke (H1), the upper part (3) of the hot press can move in the axial direction (P1) so that the upper part (4) of the cover and the lower part (6) of the hot press form a vacuum-sealed inner space (12) of the cover, while the vulcanizing mold is still open to allow gas to pass through; - wherein in the second stroke (H2), the upper part (3) of the hot press can continue to move in the axial direction (P1) so that the vulcanizing mold can be completely closed under vacuum conditions in the inner space (12) of the cover.

Description

Technical Field

[0001] This invention relates to a hot press for vulcanizing vehicle tires, the hot press having an upper part and a lower part, wherein a container with a molding component having a vulcanizing mold and a columnar upper cover surrounding the container are arranged in the upper part of the hot press, and wherein the upper and lower parts of the hot press are connected to the container in such a way that the molding component of the vulcanizing mold can be closed in the radial direction when the upper part of the hot press travels down through a stroke in the axial direction. The invention also relates to a method for vulcanizing green tires in the aforementioned hot press. Background Technology

[0002] The aforementioned hot press is a standard hot press used for vulcanizing vehicle tires under atmospheric conditions.

[0003] The hot press includes a container comprising a vulcanizing mold that is actually segmented, having molded sections for shaping the tire, sidewall shells, and flange rings. Additionally, a heating chamber is arranged for regulating the temperature of the shaping components. During vulcanization, the container is surrounded by a closed hood, which in the prior art is primarily used to insulate against temperature during vulcanization.

[0004] To minimize defects on the tire surface, air must be removed between the green tire surface and the molding surface of the vulcanizing mold. For this purpose, it is typically known to install 1000 to 5000 venting valves in the molding component. These valves allow air from the mold cavity to be expelled radially and axially through venting channels. However, these valves must be equipped on the molding components of new vulcanizing molds. Furthermore, these valves are prone to becoming contaminated due to the penetration of rubber from the tire being vulcanized, necessitating costly replacement or cleaning. Summary of the Invention

[0005] The objective of this invention is to provide a hot press for vulcanizing vehicle tires, which enables reliable vulcanization of vehicle tires without the need for an vent valve in the vulcanization mold. A further objective of this invention is to provide a method for efficiently vulcanizing vehicle tires using the aforementioned hot press.

[0006] Regarding hot presses, this objective is achieved through the following means:

[0007] - The upper part of the cover is fixedly arranged on the upper part of the hot press;

[0008] -The diameter of the upper part of the cover is determined such that the upper part of the cover can slide over the lower part of the hot press with a small clearance, and the length of the upper part of the hot press is sufficient to form a closed internal space of the cover by the lower part of the hot press and the upper part of the hot press while the vulcanizing mold is still open.

[0009] -At least one vacuum-sealing seal is arranged on the plane on which the upper part of the cover slides across the lower part of the hot press when the internal space of the cover is closed, so that the closed internal space of the cover can be sealed in a vacuum-sealed manner, wherein the seal is preferably arranged at the lower part of the hot press.

[0010] - In the first stroke, the upper part of the hot press can move along the axial direction P1 to form a vacuum-sealed internal space between the upper part of the cover and the lower part of the hot press, while the vulcanizing mold remains open to allow gas to pass through.

[0011] - A pump and a vacuum tank are arranged therein, by means of which a vacuum can be generated in the internal space of the enclosure after the first stroke, wherein the vacuum tank and the pump are connected to the internal space of the enclosure, and wherein the vacuum tank and the pump are connected to each other; and

[0012] - In the second stroke, the upper part of the hot press can continue to move along the axial direction P1 so that the vulcanizing mold can be completely closed under vacuum conditions in the internal space of the cover.

[0013] Importantly, the vehicle tires are vulcanized under vacuum conditions using a hot press according to the invention. The vulcanization mold itself does not have venting devices for venting air from the mold cavity. By vulcanizing under vacuum conditions, the 1,000 to 5,000 venting valves arranged in the vulcanization mold in the prior art to radially expel air from the mold cavity are eliminated. Therefore, there is no need to post-treat the rubber burrs on the tire caused by the venting devices, and there is no need to replace and clean venting valves that are no longer in use. This is both time-efficient and cost-effective. Furthermore, by vulcanizing under vacuum conditions, the vulcanized tires achieve a defect-free and thus perfect shape.

[0014] A vacuum (achieved within a closed chamber after the first stroke in the upper part of the hot press) is used to remove air from the still-open vulcanizing mold, particularly between the outer surface of the tire and the molding surface of the molded parts of the vulcanizing mold. After a second stroke under vacuum conditions within the chamber in the upper part of the hot press, the vulcanizing mold can be completely closed. High-quality, defect-free processing of the tires to be vulcanized is possible.

[0015] Of course, the shroud or hot press can have additional seals to achieve a vacuum-sealed interior space. To be clear, no changes should be made to the container or vulcanizing mold itself regarding the vacuum sealing measures.

[0016] The term "vacuum" refers to an air pressure in the range of 950 mbar (absolute value) to 0.1 mbar (absolute value).

[0017] Conveniently, the seal is an annular seal with a circular, polygonal, or flat cross-section.

[0018] For achieving reliable sealing performance, it is advantageous that the annular seal is arranged in a groove, wherein the diameter of the annular seal is slightly larger than the depth of the groove. "Slightly larger than" means that the seal is compressed by up to 40% when it is installed in the groove and in a sealed state, compared to the uncompressible geometry of the seal. Furthermore, the precise design of the groove relative to the seal geometry prevents damage to the seal and improves durability.

[0019] In one embodiment of the invention, the annular seal is formed of a solid material. This solid material can be formed of one or more known materials used for seals, such as FKM or FFKM. These seals are cost-effective and easy to operate.

[0020] In another embodiment of the invention, the annular seal is a flexible tube with a variable diameter. The advantage is that the annular seal is subjected to a smaller load and its diameter is increased only when a sealing effect is required.

[0021] Advantageously, the annular seal is a double-annular seal with different inflation properties. This allows for compensation for potential leaks with less pump power.

[0022] The advantage is that the volume of a vacuum chamber is approximately 5 to 10 times that of a closed enclosure (including molds, containers, tire blanks, and heating bellows). This ensures that a vacuum can be reliably generated within the enclosure. Furthermore, the time required to generate the desired vacuum is significantly reduced. This can be done during normal loading and unloading processes.

[0023] Regarding the method of using the above-mentioned hot press, the present invention is achieved by sequentially performing the following steps:

[0024] a) Loading the opened hot press by placing the green tire to be vulcanized into a container;

[0025] b) Move the upper part of the hot press in the axial direction toward the lower part of the hot press for a first stroke until a closed internal space of the cover is obtained, formed by the upper part of the cover, the upper part of the hot press and the lower part of the hot press, while the vulcanizing mold is still open.

[0026] c) Only when the annular seal is a flexible hose with a variable diameter: inflate the annular hose seal to seal the internal space of the cover in a vacuum-sealed manner.

[0027] d) Connect the vacuum tank to the internal space of the shroud so that a partial vacuum can be generated in the vacuum-sealed internal space of the shroud through pressure compensation between the vacuum tank and the internal space of the shroud;

[0028] e) In the case of obtaining a partial vacuum in the space inside the shroud: disconnect the connection between the vacuum tank and the space inside the shroud, connect the connection between the space inside the shroud and the pump, and pump out the remaining air from the space inside the shroud to create a vacuum.

[0029] f) Move the upper part of the hot press in a second stroke, during which the container is moved such that the vulcanizing mold is completely closed, and then disconnect the connection between the inner space of the shroud and the pump.

[0030] g) Vulcanize the green tire and connect the pump to the vacuum tank and create a vacuum in the vacuum tank, wherein the connection between the pump and the internal space of the shroud and the connection between the vacuum tank and the internal space of the shroud are disconnected.

[0031] h) Open the hot press and unload the vulcanized tires by moving the top of the hot press;

[0032] And repeat steps a)–h) to vulcanize the individual tires.

[0033] Advantageously, in order to facilitate step h), another valve arranged in the shroud is opened in advance to break the vacuum in the shroud and then closed again. Attached Figure Description

[0034] The following two schematic figures illustrate an embodiment of the hot press and a method for vulcanizing pneumatic vehicle tires under vacuum conditions, along with other advantages. In the figures:

[0035] Figure 1 A hot press according to the invention is shown, wherein the container is in an open state;

[0036] Figure 2 Showing the closed state Figure 1 A hot press.

[0037] List of reference numerals

[0038] 1. Hot press

[0039] 2 containers

[0040] 3. Upper part of the hot press

[0041] 4. Upper part of the cover

[0042] 5. Annular seal

[0043] 6. Lower part of the hot press

[0044] 7. Lower part of the upper part of the cover

[0045] 8. Central Institutions

[0046] 9. Annular seal

[0047] 10 pumps

[0048] 11 Vacuum tank

[0049] 12. Internal space of the cover = Internal space of the cover

[0050] 13 Lower heating plate

[0051] 14 Lower sidewall shell

[0052] 15. Upper heating plate

[0053] 16 Upper sidewall shell

[0054] 17 Lower flange ring

[0055] 18 Upper flange ring

[0056] 19-section ring

[0057] 20-section guide shoe

[0058] 21 Molding Section / Forming Section

[0059] 22 Locking ring

[0060] 23. Length of the upper part of the cover

[0061] P1 Axial direction

[0062] P2 Radial direction

[0063] H1 First Trip

[0064] H2 Second Trip Detailed Implementation

[0065] Figure 1 A hot press 1 according to the invention is shown, wherein the container 2 is in the open state. A tire blank can be introduced into the hot press 1.

[0066] The hot press 1 includes a lower part 6 and an upper part 3. The upper part has a columnar upper cover 4, and the hot press has corresponding mechanisms for positioning the tire to be vulcanized, manipulating the components of the vulcanizing mold, introducing the heating medium, and removing the vulcanized tire. At the upper part 3, a container 2 is arranged in the internal space of the upper cover 4, such that when the upper part 3 moves in the axial direction P1, the molding components of the vulcanizing mold arranged in the container 2 can move in the radial direction P2.

[0067] A "central mechanism" 8 is arranged, on which a heating capsule (not shown) is attached. This heating capsule can be incorporated into a tire blank (not shown). In addition, nozzles (not shown) are arranged on the central mechanism 8, through which a heating medium can be introduced into the heating capsule (not shown).

[0068] The columnar upper part 4 is fixedly mounted on the upper part 3 of the hot press, and its length 23 is sufficient to allow the lower part 6 of the hot press and the upper part 3 of the hot press to form a closed inner space 12 of the cover while the vulcanizing mold is still open (i.e., when the upper part 3 of the hot press has not been completely moved onto the lower part 6 of the hot press).

[0069] The upper part 4 of the cover is air-sealed or vacuum-sealed, and forms a vacuum-sealed internal space 12 in the closed state. To seal the upper part 4 of the cover in a vacuum-sealed manner in the closed state, an annular seal 5 is arranged at the lower part 6 of the hot press at a position where the upper part 4 of the cover travels through the lower part 6 of the hot press in the closed state. An additional annular seal 9 at least vacuum-seals the central mechanism 8 relative to the internal space 12 of the cover.

[0070] Container 2 is a conventional container 2 known in the prior art.

[0071] Container 2 includes a segmented vulcanizing mold having a lower heating plate 13, a lower sidewall shell 14, an upper heating plate 15, an upper sidewall shell 16, a lower flange ring 17, and an upper flange ring 18. The components of the vulcanizing mold that move in the vertical (=axial) direction (arrow P1) for opening and closing include: a segment ring 19 consisting of seven to nine segment guide shoes 20, a molding / molding segment 21 fastened to the segment ring, and an upper sidewall shell 16 with the upper flange ring 18. The segment guide shoes 20 are radially (in the direction of arrow P2) separated from each other to close and open the vulcanizing mold. A locking ring 22 is arranged on the upper heating plate 15, having an inclined inner surface that interacts with the inclined outer surface of the segment guide shoes 20 of the segment ring 19, causing the segment guide shoes 20 to move together radially to close the segment ring 19 when the vulcanizing mold is closed. The lower heating plate 13, the upper heating plate 15, and the locking ring 22 contain heating chambers into which at least one heating medium, particularly saturated vapor (water vapor), is introduced to vulcanize the tire. In this way, the green tire is heated from the outside (not shown) by means of the section guide shoe 20, the sidewall housings 14, 16, and the flange rings 17, 18; therefore, this heating is often referred to as external heating.

[0072] A conventional heating bladder (not shown) is arranged in a known manner and is filled under pressure with at least one heating medium to place the green tire at the center of the mold from the inside, wherein the heating bladder is formed into an annular shape adapted to the tire. This type of heating, after the green tire is heated from the inside by the heating bladder, is called internal heating.

[0073] In the first stroke H1 (not shown in the figure), the upper part 3 of the cover can move along the axial direction P1 such that the lower region 7 of the upper part 4 of the cover passes through the lower part 6 of the hot press and forms a vacuum-sealed inner space 12 of the cover, while the vulcanizing mold remains open to allow gas to pass through.

[0074] A pump 10 and a vacuum tank 11 are arranged, which enable a vacuum to be generated in the internal space 12 of the casing after the first stroke H1. The vacuum tank 11 and the pump 10 are connected to the internal space 12 of the casing, and the vacuum tank 11 and the pump 10 are connected to each other. With the vacuum in the internal space 12 of the casing (= the internal space of the casing) (especially in the tire forming and vulcanization process), the conventional vent valves arranged on the molding surface of the vulcanizing mold are completely eliminated.

[0075] Figure 2 Showing the closed state Figure 1 The hot press 1 is closed after the second stroke H2, during which the upper part 3 of the hot press can continue to move in the axial direction P1 so that the vulcanizing mold is completely closed under vacuum conditions in the inner space 12 of the cover. The connection between the vacuum tank 11 and the inner space 12 of the cover is disconnected. Subsequently, the connection between the inner space 12 of the cover and the pump 10 is disconnected. Vulcanization is then performed on the green tire.

[0076] In the case of passenger vehicle tires, the vulcanization process lasts approximately 15 minutes. During this time, the connection between pump 10 and vacuum tank 11 is activated to create a vacuum in vacuum tank 11, wherein the connection between pump 10 and the cover, and the connection between vacuum tank 11 and the cover, are respectively disconnected. After the vulcanization of the tire is completed, the volume of the internal space 12 of the cover is inflated by means of a valve (not shown) and the hot press 1 is turned on to unload the vulcanized tire from the container 2 containing the vulcanization mold. For this purpose, the upper part 3 of the hot press, together with the container 2, moves upward, and the molding section 21 is simultaneously moved outward in the radial direction P2. The tire is then released.

Claims

1. A hot press for vulcanizing vehicle tires under vacuum conditions (1). - The hot press has an upper part (3) and a lower part (6), wherein a container (2) with molding parts (14, 16, 17, 18, 21) of a vulcanizing mold and a columnar upper cover (4) surrounding the container are arranged in the upper part (3), and wherein the upper part (3) and the lower part (6) are connected to the container (2) in such a way that when the upper part (3) moves down through a stroke in the axial direction (P1), the molding parts (14, 16, 17, 18, 21) of the vulcanizing mold can be closed in the radial direction (P2). -The upper part (4) of the cover is fixedly arranged at the upper part (3) of the hot press; -The diameter of the upper part of the cover (4) is determined such that the upper part of the cover can slide over the lower part of the hot press (6) with a small clearance, and the length (23) of the upper part of the hot press is sufficient to form a closed inner space (12) of the cover by the lower part of the hot press (6) and the upper part of the hot press (3) while the vulcanizing mold is still open. -At least one vacuum-sealed seal (5) is arranged on the plane on which the upper part (4) of the cover slides over the lower part (6) of the hot press when the inner space (12) of the cover is closed, so that the closed inner space (12) of the cover can be sealed in a vacuum-sealed manner. - In the first stroke (H1), the upper part (3) of the hot press can move in the axial direction (P1) to form a vacuum-sealed inner space (12) between the upper part (4) of the cover and the lower part (6) of the hot press, while the vulcanizing mold is still open to allow gas to pass through; -A pump (10) and a vacuum tank (11) are arranged therein, by means of which a vacuum can be generated in the internal space (12) of the enclosure after the first stroke (H1), wherein the vacuum tank (11) and the pump (10) are connected to the internal space (12) of the enclosure, and wherein the vacuum tank (11) and the pump (10) are connected to each other, wherein the volume of the vacuum tank (11) is 5 to 10 times the volume of the closed enclosure; and - In the second stroke (H2), the upper part (3) of the hot press can continue to move in the axial direction (P1) so that the vulcanizing mold can be completely closed under vacuum conditions in the inner space (12) of the cover.

2. The hot press (1) according to claim 1, characterized in that, These seals are annular seals with circular, polygonal, or flat cross-sections (5, 9).

3. The hot press (1) according to claim 2, characterized in that, The annular seal (5, 9) is arranged in an annular groove, wherein the diameter of the annular seal (5, 9) is slightly larger than the depth of the groove.

4. The hot press (1) according to claim 2 or 3, characterized in that, The annular seal (5, 9) is formed of solid material.

5. The hot press (1) according to claim 2 or 3, characterized in that, The annular seal (5, 9) is a flexible tube with a variable diameter.

6. The hot press (1) according to claim 2 or 3, characterized in that, The annular seal (5, 9) is a double annular seal with different inflation properties.

7. The hot press (1) according to claim 1 or 2, characterized in that, The seal (5) is located at the lower part (6) of the hot press.

8. A method for vacuum vulcanizing vehicle tires in a hot press, the method being used for vulcanizing pneumatic vehicle tires under vacuum conditions in a hot press (1) according to any one of claims 1 to 7, characterized in that, Perform the following steps in sequence: a) Loading the opened hot press (1) by placing the green tire to be vulcanized into the container (2); b) Move the upper part (3) of the hot press in the axial direction (P1) toward the lower part (6) of the hot press for a first stroke (H1) until a closed inner space (12) of the cover (4), the upper part (3) of the hot press and the lower part (6) of the hot press is obtained, while the vulcanizing mold is still open. d) Connect the vacuum tank (11) to the inner space (12) of the shroud so as to generate a partial vacuum in the vacuum-sealed inner space (12) through pressure compensation between the vacuum tank (11) and the inner space (12); e) In the case of obtaining a partial vacuum in the inner space (12) of the hood: disconnect the connection between the vacuum tank (11) and the inner space (12) of the hood, connect the connection between the inner space (12) of the hood and the pump (10) and pump out the remaining air from the inner space (12) of the hood to create a vacuum; f) Move the upper part (3) of the hot press in a second stroke (H2), in which the container (2) is moved so that the vulcanizing mold is completely closed, and then disconnect the connection between the inner space (12) of the cover and the pump (10); g) Vulcanize the green tire and connect the pump (10) to the vacuum tank (11) and create a vacuum in the vacuum tank (11), wherein the connection between the pump (10) and the inner space (12) of the enclosure and the connection between the vacuum tank (11) and the inner space (12) of the enclosure are respectively disconnected; h) Open the hot press (1) and unload the vulcanized tire by moving the upper part (3) of the hot press; And repeat steps a) – h) to vulcanize the individual tires.

9. The method for vacuum vulcanizing vehicle tires in a hot press according to claim 8, characterized in that, To facilitate step h), another valve located in the upper part (4) of the cover is opened in advance to break the vacuum and then closed again.

10. A method for vacuum vulcanizing a vehicle tire in a hot press, the method being used for vulcanizing a pneumatic vehicle tire in a hot press (1) according to any one of claims 2 to 7 under vacuum conditions, wherein the annular seal (5, 9) is a flexible tube of variable diameter, characterized in that, Perform the following steps in sequence: a) Loading the opened hot press (1) by placing the green tire to be vulcanized into the container (2); b) Move the upper part (3) of the hot press in the axial direction (P1) toward the lower part (6) of the hot press for a first stroke (H1) until a closed inner space (12) of the cover (4), the upper part (3) of the hot press and the lower part (6) of the hot press is obtained, while the vulcanizing mold is still open. c) Inflate these annular hose seals to seal the interior space of the enclosure in a vacuum-sealed manner (12). d) Connect the vacuum tank (11) to the inner space (12) of the shroud so as to generate a partial vacuum in the vacuum-sealed inner space (12) through pressure compensation between the vacuum tank (11) and the inner space (12); e) In the case of obtaining a partial vacuum in the inner space (12) of the hood: disconnect the connection between the vacuum tank (11) and the inner space (12) of the hood, connect the connection between the inner space (12) of the hood and the pump (10) and pump out the remaining air from the inner space (12) of the hood to create a vacuum; f) Move the upper part (3) of the hot press in a second stroke (H2), in which the container (2) is moved so that the vulcanizing mold is completely closed, and then disconnect the connection between the inner space (12) of the cover and the pump (10); g) Vulcanize the green tire and connect the pump (10) to the vacuum tank (11) and create a vacuum in the vacuum tank (11), wherein the connection between the pump (10) and the inner space (12) of the enclosure and the connection between the vacuum tank (11) and the inner space (12) of the enclosure are respectively disconnected; h) Open the hot press (1) and unload the vulcanized tire by moving the upper part (3) of the hot press; And repeat steps a) – h) to vulcanize the individual tires.

11. The method for vacuum vulcanizing vehicle tires in a hot press according to claim 10, characterized in that, To facilitate step h), another valve located in the upper part (4) of the cover is opened in advance to break the vacuum and then closed again.

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