HEATING PRESS FOR VULCANIZING A VEHICLE TIRE

Description

[0001] The invention relates to a heating press for vulcanizing a vehicle tire with a two-part hood consisting of an upper hood part and a lower hood part and with a container arranged in the upper hood part, which container has the vulcanizing mold with the mold parts for molding the tire, wherein the upper hood part and the lower hood part are connected to the container in such a way that when the hood parts are moved together over a total stroke in the axial direction, in which the open end of the upper hood part can be immersed into the open end of the lower hood part with almost no play, the mold parts of the vulcanizing mold can be closed in the radial direction, wherein the total stroke consists of a first partial stroke and a second partial stroke,wherein after the first partial stroke, the hood parts overlap in a first overlapping area and the vulcanizing mold is still open, and wherein after the second partial stroke, the hood parts overlap in a second larger overlapping area and the vulcanizing mold is closed, wherein for generating a vacuum in the hood interior, the upper part of the hood and the lower part of the hood are designed to be airtight, at least one ring seal is arranged in at least one of the two hood parts in the region of the first overlapping area.

[0002] The heating press described above is a standard heating press for vulcanizing vehicle tires under atmospheric conditions.

[0003] The curing press comprises a so-called container, which houses the actual segmented vulcanizing mold with the tire-shaping mold segments, sidewall shells, and bead rings. Heating chambers are also provided for tempering the molded parts. During vulcanization, the container is surrounded by a two-part, closed hood, which, in the prior art, primarily serves to insulate the temperature during vulcanization.

[0004] A heating press of the type mentioned above is known, for example, from DE 17 79 130 A1. The heating press has a hood consisting of an upper hood section and a lower hood section. When the hood sections are moved together, the open end of the upper hood section dips into the open end of the lower hood section. After a first partial stroke of the hood sections, they overlap in a first overlap area, with the vulcanizing mold still open. While the vulcanizing mold is still open, a vacuum is created in it. Subsequently, a second partial stroke is performed, closing the vulcanizing mold. On the inside of the lower hood section, an annular seal is provided, against which the upper hood section is pressed when the heating press is closed. The proposed heating press is intended to prevent extrusion during vulcanization, shorten the vulcanization time, and low heat consumption.

[0005] From DE 747 214 C a heating press with an evacuatable hood interior is known, wherein a switchable vacuum line is connected to the steam chamber to generate the vacuum.

[0006] To minimize imperfections on the tire surface, the air between the green tire surface and the mold surface must be removed. For this purpose, it is generally known that 1,000 to 5,000 vent valves must be provided in the mold surfaces of the molded parts. These vent valves discharge the air from the mold cavity radially and axially outward through vent channels. However, the molded parts of a new vulcanizing mold must be equipped with these valves. Furthermore, these valves tend to become dirty due to rubber from the tire being vulcanized penetrating them, so they must be replaced or cleaned, which is a laborious process.

[0007] The invention is based on the object of providing a heating press for vulcanizing a vehicle tire under vacuum, with which vehicle tires can be reliably vulcanized under vacuum and without the need for vent valves in the vulcanizing mold. Furthermore, a method for the time-efficient vulcanization of a vehicle tire under vacuum is provided.

[0008] The task is solved by creating a vacuum in the hood interior a vacuum can be generated in the hood interior by means of a pump and a vacuum tank, and the vacuum tank and the pump are connected to the hood interior, and the vacuum tank and the pump are connected to each other, where the ring seal is a hose with variable diameter or a differentially pumped double ring seal.

[0009] The vacuum is used to remove the air from the vulcanizing mold, especially between the outer surface of the tire and the molding surfaces of the molding parts of the vulcanizing mold, in order to produce the tire to be vulcanized with high quality and without defects.

[0010] Another important aspect is that the vulcanizing mold itself does not have any venting devices for venting the mold cavity. Vulcanization under vacuum eliminates the need for the 1,000 to 5,000 venting valves typically found in the vulcanizing mold, which are used in the prior art to radially vent the air from the mold cavity. This eliminates the need to rework the rubber vents on the tire created by the venting devices, nor to replace or clean deflated vent valves. This saves time and money. Furthermore, vacuum vulcanization gives the vulcanized tire an external shape that is completely free of defects and thus appears perfect.

[0011] Furthermore, it is essential to the invention that only the two-part hood is modified in such a way that, thanks to a newly arranged seal, it is airtight from the stage of the first partial stroke and maintains a vacuum within it. No changes are expressly intended to be made to the container or the vulcanizing mold with regard to airtight measures.

[0012] The term vacuum refers to air pressure in the range from 950 mbar (abs) to 0.1 mbar (abs). The ring seal preferably has a round or square cross-section.

[0013] The hose, which can be adjusted in diameter, has the advantage that the ring seal is subjected to less stress due to relative movements between the hood parts and its diameter is only increased when the sealing effect is required.

[0014] The differentially pumped double ring seal has the advantage that any leaks can be compensated with low pumping power.

[0015] It is advantageous if the ring seal is located in the hood's lower section. The hood's lower section is typically stationary, while the hood's upper section performs the axial movement. The vacuum is created by ensuring that the hood's upper and lower sections are sealed against each other by at least one ring seal each.

[0016] In order to improve the mechanical support of the two hood parts against each other, sliding bands made of abrasion-resistant high-temperature polymer, such as PEEK, are used in addition to the seals.

[0017] It is advantageous if the ring seal is arranged in a circular groove, with the diameter of the ring seal in the sealed state being slightly larger than the depth of the groove. Slightly larger means that the seal is compressed by a maximum of 40% when installed in the groove and in the sealed state compared to the compression-free geometry of the seal. The precise design of the groove in relation to the seal geometry prevents damage to the seal(s) due to the relative movement of the two cover parts and improves durability.

[0018] It is advisable for the vacuum tank to have a volume approximately 5 to 10 times larger than the volume of the closed hood (including mold, container, green tire, and bladder). This ensures that a vacuum can be reliably generated within the hood. Furthermore, the time required to generate the necessary vacuum is significantly reduced. This can take place during the normal loading and unloading process.

[0019] An embodiment of a heating press and a method for vacuum vulcanization of a pneumatic vehicle tire, including further advantages, are shown in the following schematic Figures 1 to 4 described. They show: Fig. 1 shows a heating press according to the invention with a container in the open state; Fig. 2 shows the heating press of the Fig. 1 in the closing phase after a first partial stroke; Fig. 3 the heating press of the Fig. 1 and the Fig. 2in the closed state after a second partial stroke; Fig. 4 shows another heating press according to the invention with a container in the open state.

[0020] The Fig. 1 shows a heating press 1 according to the invention with a container 2 in the open state. The green tire can be inserted into the heating press 1.

[0021] The heating press 1 comprises an upper press section 3, which is connected to the upper hood section 4, and a lower press section 6, which is connected to the lower hood section 7. The press sections 6 and 7 have the corresponding mechanisms for positioning the tire to be vulcanized, for operating the components of the vulcanization mold, for introducing the heating media, and for removing the fully vulcanized tire. During the vulcanization process, the container 2 is enclosed by the two-part hood consisting of the upper hood section 4 and the lower hood section 7. A "center mechanism" 8 is arranged. Attached to the center mechanism 8 is a heating bladder (not shown), which can be inserted into the green tire (not shown). Nozzles (not shown) are also arranged on the center mechanism 8, through which a heating medium can be introduced into the heating bladder (not shown).

[0022] The hood upper part 4 and the hood lower part 7 are designed to be airtight or vacuum-tight and for this purpose have seals 5 between the hood parts 4, 7 and the central mechanism 8. In order to make the closed hood made up of the two hood parts 4, 7 vacuum-tight, an annular seal 9 is also arranged in the hood lower part 7, which faces the hood interior ( Fig.1-3 ) or in another embodiment of the invention into the outer space of the hood ( Fig. 4 ). When executing the Fig. 1-3 the hood upper part 4 has a smaller diameter than the hood lower part 7 and thus dips into the hood lower part 7. The other embodiment of the invention of the Fig. 4 differs from the execution of the Fig. 1-3that the seal in the hood lower part 7 faces the hood exterior and the diameter of the hood upper part 4 is larger than the diameter of the hood lower part 7, so that the hood upper part 4 encloses the hood lower part 7 when the hood parts move together. The annular seal 9 is a hose with an adjustable diameter 26 and is arranged in a groove 25 which is arranged on the side facing the hood upper part 4 in the hood lower part 7. The diameter 26 of the annular seal 9 is slightly larger than the depth 27 of the groove 25.

[0023] A vacuum can be generated in the hood interior 12 by means of a pump 10 and a vacuum tank 11, wherein the vacuum tank 11 and the pump 10 are connected to the hood interior 12, and wherein the vacuum tank 11 and the pump 10 are connected to one another. A vacuum in the hood interior 12, particularly during tire molding and vulcanization, completely eliminates the need for vent valves conventionally arranged in the molding surface of the vulcanizing mold.

[0024] Container 2 is a conventional container 2 that is already known in the state of the art.

[0025] The container 2 contains the segmented vulcanizing mold with a lower heating plate 13, a lower side wall shell 14, an upper heating plate 15, an upper side wall shell 16, a lower bead ring 17 and an upper bead ring 18. The components of the vulcanizing mold that are moved in the vertical direction (arrow P1) for opening and closing include the segment ring 19 consisting of seven to nine segment shoes 20 and the profile / mold segments 21 attached to it as well as the upper side wall shell 16 with the upper bead ring 18. The segment shoes 20 are moved radially in the direction of the arrow P2 when the vulcanizing mold is opened. Fig. 1, are moved apart and thus release the fully vulcanized tire. A closing ring 22 is arranged on the upper heating plate 15. The closing ring 22 has a beveled inner surface which interacts with beveled outer surfaces of the segment shoes 20 of the segment ring 19 in such a way that when the vulcanization mold is closed, the segment shoes 20 are moved together in the radial direction to form the closed segment ring 19. The lower heating plate 13, the upper heating plate 15 and the closing ring 22 contain heating chambers into which at least one heating medium, in particular saturated steam (steam), is introduced to vulcanize the tire. In this way, the green tire (not shown) is heated from the outside via the segment shoes 20, the sidewall shells 14, 16 and the bead rings 17, 18, so that this heating is usually referred to as external heating.

[0026] A conventional heating bladder (not shown) is arranged in a known manner and is filled with at least one heating medium under pressure to center the green tire in the mold from the inside, whereby the heating bladder is formed into a torus shape appropriate for the tire. Since the green tire is heated from the inside via the heating bladder, this type of heating is referred to as internal heating.

[0027] In the Fig. 2 is the heating press 1 of the Fig. 1shown in the closing phase after a first partial stroke TH 1. After a first partial stroke TH 1, the open end of the upper hood part 4 is moved in the axial direction by a certain stroke in order to immerse itself in the open end of the stationary lower hood part 7 with almost no play. The hood parts 4, 7 overlap one another in a first overlap area 28, in which the ring seal 9 is arranged. The vulcanization mold is still open. The hood made up of the two hood parts 4, 7 is now vacuum-tight by the ring seal 9. The connection between the vacuum tank 11 and the hood 4, 7 is opened to generate a vacuum in the hood 4, 7, with the vacuum tank 11 being in a vacuum state. This vacuum was created by the pump 10 during the preceding vulcanization period of the previous tire. The vacuum tank 11 has a volume which is approximately 5 to 10 times larger than the volume of the closed hood 4, 7.

[0028] The Fig. 3 shows the heating press of the Fig. 1 and the Fig. 2 in closed state after a 2nd partial stroke TH 2 . After in the closed hood 4, 7 of the Fig. 2 Once a vacuum has been created, the airless vulcanizing mold is completely closed by carrying out a second partial stroke TH 2 and the connection between the vacuum tank 11 and the hood 4, 7 is closed.

[0029] The sum of the 1st partial stroke TH 1 and the 2nd partial stroke TH 2 results in the total stroke GH. The tire is vulcanized. Vulcanizing a car tire takes approximately 15 minutes. During this time, the connection between pump 10 and vacuum tank 11 is opened to create a vacuum in the vacuum tank 11, with the connection between pump 10 and hood 4, 7 and the connection between vacuum tank 11 and hood 4, 7 both closed. Once the tire has been vulcanized, the hood volume of hoods 4, 7 is vented via a valve (not shown) and the heating press 1 is opened to unload the fully vulcanized tire from the vulcanizing mold. To do this, the upper part of the hood 4 first moves up and the tread segments 21 are simultaneously moved outwards in a radial direction. The tire is released. List of reference symbols (part of the description)

[0030] 1 Heating press 2 Container 3 Heating press upper section 4 Hood upper section 5 Seal 6 Press lower section 7 Hood lower section 8 Center mechanism 9 Ring seal 10 Pump 11 Vacuum tank 12 Hood interior 13 Lower heating plate 14 Lower side wall shell 15 Upper heating plate 16 Upper side wall shell 17 Lower bead ring 18 Upper bead ring 19 Segment ring 20 Segment shoe 21 Profile segment / mold segment 22 Locking ring 23 Lower edge of the hood upper section 24 Upper edge of the hood lower section 25 Groove 26 Diameter of the ring seal 27 Depth of the groove 28 1st overlap area 29 2nd overlap area TH 1 1st partial stroke TH 2 2nd partial stroke GH Total stroke

Claims

1. Heating press (1) for vulcanizing a vehicle tyre, having a two-part hood (4, 7) composed of a hood upper part (4) and a hood lower part (7) and having a container (2) which is arranged in the hood upper part (4) and which has the vulcanizing mould with the mould parts (14, 16, 17, 18, 21) for the moulding of the tyre, wherein the hood upper part (4) and the hood lower part (7) are connected to the container (2) such that, as the hood parts (4, 7) are brought together over a total stroke (GH) that takes place in an axial direction (P1), during which process the open end of the hood upper part (4) can be caused to enter virtually without play into the open end of the hood lower part (7), the mould parts (14, 16, 17, 18, 21) of the vulcanizing mould can be closed in a radial direction (P2), wherein the total stroke (GH) is composed of a first partial stroke (TH1) and a second partial stroke (TH2), wherein, after the first partial stroke (TH1), the hood parts (4, 7) overlap in a first overlap region (28) and the vulcanizing mould is still open, and wherein, after the second partial stroke (TH2), the hood parts (4, 7) overlap in a second, larger overlap region (29) and the vulcanizing mould is closed, wherein, to enable a vacuum to be generated in the hood interior (12), - the hood upper part (4) and the hood lower part (7) are designed to be airtight, - at least one ring seal (9) is arranged in at least one of the two hood parts (4, 7) in the region of the first overlap region (28), characterized in that, to generate the vacuum in the hood interior (12), - the vacuum can be generated in the hood interior (12) by means of a pump (10) and a vacuum tank (11), and wherein the vacuum tank (11) and the pump (10) are connected to the hood interior (12) and wherein the vacuum tank (11) and the pump (10) are connected to one another, wherein the ring seal (9) is a hose that is variable in terms of its diameter (26) or is a differentially inflated double ring seal.

2. Heating press (1) according to Claim 1, characterized in that the ring seal (9) is arranged in the hood lower part (7).

3. Heating press (1) according to Claim 1 or 2, characterized in that the ring seal (9) is arranged in a circular-ring-shaped groove (25), wherein the diameter of the ring seal (26) is slightly greater than the depth of the groove (27).

4. Heating press (1) according to one or more of the preceding claims, characterized in that sliding bands composed of wear-resistant high-temperature polymer, such as of PEEK, are arranged in the first overlap region (28) of the two hood parts (4, 7).

5. Heating press (1) according to one or more of the preceding claims, characterized in that the vacuum tank (11) has a volume that is approximately 5 to 10 times greater than the volume of the closed hood (4, 7).