Heating device for a tire heating press, tire heating press and method for manufacturing tires

Abstract

The invention relates to a heating device for a tire heating press, a tire heating press with a heating device, and a method for manufacturing tires. According to the invention, the heating device has at least one intermediate storage tank in which heat transfer fluid can be temporarily stored after the vulcanization of a tire and reused in a subsequent process.

Description

The invention relates to a heating device for a tire heating press.The invention furthermore relates to a tire heating press having at least one vulcanization chamber and at least one heating device for vulcanizing a tire in the at least one vulcanization chamber.The invention further relates to a method for producing tires using such a tire heating press.Tire heating presses generally have at least one vulcanization chamber in which a raw tire is shaped and vulcanized using molds and pressure. For vulcanization of the tire, it is necessary to heat it. For this purpose, thermal energy is supplied to the raw tire.Various embodiments of heating systems are already known for supplying the thermal energy to the tire. Traditionally, this is done by supplying a heat carrier, e.g. hot steam, to the area of the molds (exterior heating) and / or to the interior of the tire to be vulcanized (interior heating).Many embodiments of tire heating presses include a bladder expandable in the vulcanization chamber inboard of the tire to be vulcanized. By means of the bellows, the tire to be vulcanized can be pressed into the mold or mold segments arranged around the tire in the vulcanization chamber.In known embodiments of an interior heating system, a heat carrier, for example hot steam, is introduced under pressure into the bellows, so that the tire to be vulcanized is heated from the inside. Electrical internal heating systems are also already known, in particular in the form of heating elements arranged in the bellows in combination with a fan.For the generation of hot steam, water and a large amount of energy are required. Therefore, the use of inert gas, in particular nitrogen, as an alternative heat carrier alone or in combination with hot steam is also already known.In the known heating systems for tire heating presses, the discharge of the heat carrier, for example a steam-nitrogen condensate mixture, into a heat carrier sink takes place after each vulcanization cycle. For each new vulcanization cycle, a new provision of heat carrier heated for this is effected. This requires time and energy, so that the vulcanization process is long and energy intensive.The residual heat present in the discharged heat carrier, the pressure and the heat carrier as such cannot be recycled or can only be recycled to a slight extent.It is therefore an object of the invention to provide a heating device for a tire heating press which at least partially overcomes the above mentioned problems.This object is achieved according to the invention by a heating device for a tire heating press according to claim 1.It is a further object of the invention to provide a tire heating press which at least partially overcomes the above mentioned problems.This object is achieved according to the invention by a tire heating press according to claim 9.It is a further object of the invention to provide a method for producing tires with a tire heating press which at least partially overcomes the aforementioned problems.This object is achieved according to the invention by a method for producing tyres according to claim 10.In the dependent claims advantageous aspects of the invention are claimed.The features disclosed below of a heating device for a tire heating press, a tire heating press and a method for producing tires are part of the invention in all executable combinations.A heating device according to the invention for a tire heating press has at least one heat carrier source, for example a connection to a supply line and / or a pressure accumulator, a heat carrier line and at least one intermediate accumulator, wherein the heat carrier is preferably designed as a pure inert gas.In embodiments of the invention, the heat carrier is designed as an inert gas-steam mixture. In these embodiments of the invention, the heating device preferably comprises a steam dryer.The at least one intermediate storage is designed as a pressure storage.A suitable pressure range of the pressure accumulator is, for example, 1 to 30 bar.A suitable volume for the intermediate store is, depending on the size of the tire heating press to be heated, approximately 100 l to 300 l, preferably approximately 200 l, for passenger car tires, correspondingly twice as much in the case of a double heating press and significantly more for truck tires.The intermediate storage unit enables the emptying of the heat transfer medium from the heat transfer medium line and or the integrated heating system of a connected tire heating press, in particular the bellows, into the latter, instead of removing the latter via a heat transfer medium sink or a reduced pressure system. As a result, the heat carrier as such is temporarily stored at least almost at working pressure and can be reused in subsequent process cycles of vulcanization or another process of tire production.For this purpose, the at least one intermediate storage unit is connected via a valve to the heat transfer medium line in such a way that the heat transfer medium can be discharged from the heat transfer medium line and / or the integrated heating system of a connected tire heating press into the latter and can be temporarily stored therein.In embodiments of the invention, the at least one intermediate storage device has at least one connection for connection to an aftertreatment device, such that the temporarily stored heat carrier can be used by the aftertreatment device.In embodiments of the invention, the heating device comprises at least one heater, at least one circulation pump, at least one pressure regulating device, at least one circulation line and at least one bypass line.The circulation line and the bypass line form the heat transfer line of the heating device in these embodiments.The circulation line is preferably designed for connection to the bladder of a tire heating press in such a way that the heat carrier can be conducted through the bladder and circulated in the circulation line.The heater and the circulation pump are arranged outside the bladder of a connected tire heating press in the circulation line, so that the heat carrier can be circulated through the heater.In embodiments of the invention, the circulation pump is designed to convey the heat carrier at a volume flow of about 200 I / min at a pressure of 28 bar.In preferred embodiments of the invention, the heater is designed as an electric heater. In other embodiments of the invention, other types of heating, for example realized with the aid of heat exchangers, can also be used alone or in combination with an electric heating.For connection to the bladder of a tire heating press, the heating device preferably has a connection device which provides at least two connections.The bypass line is connected to the circulation line in such a way that the section of the circulation line which extends through the bellows in a state connected to a tire heating press can be bypassed.Preferably, the heating device comprises at least one controllable bypass valve and at least two controllable circulation valves. The bypass valve is arranged in the bypass line, so that the bypass line can be opened or closed by means of the bypass valve. The circulation valves are arranged between the connection of the bypass line and the connection device for connecting the heating device to the tire heating press, so that the part of the circulation line passing through the bellows in a connected state can be opened or closed by means of the circulation valve, while the remaining part of the circulation line in conjunction with the bypass line forms a closed second circulation line for idling.The second circulation line thus forms a reservoir or a reservoir line for the heat carrier, in which the latter can be stored at an adjustable temperature by means of the circulation pump and the heater.The circulation pump and the heater are arranged in the part of the circulation line associated with the second circulation line.By this construction of the heating device, the heat carrier can be kept ready at the required temperature even in phases of the production process in which it is not required in the bellows. This is the case, for example, before and after the steps of forming and vulcanization of the tire when the bladder is compressed or contracted and the raw tire is introduced into or removed from the vulcanization chamber. This reduces the time required to heat the heat carrier.Depending on the volume of the second circulation line, the heat carrier can also be provided in sufficient quantities, so that the thermal energy to be introduced for the vulcanization of the tire is available even more quickly.In advantageous embodiments of the invention, at least one heat medium reservoir is incorporated into the second circulation line, so that the quantity of heat carrier kept ready at the required temperature can be increased.In preferred embodiments of the invention, the heat carrier is designed as nitrogen.In embodiments of the invention, the pressure regulating device is realized with the aid of a modulation valve and a pressure measuring device.In embodiments of the invention, at least one cooling device for cooling the heat carrier is integrated into the circulation line. With the aid of the cooling device, the heat carrier can be cooled, for example, after the vulcanization has taken place, so that the vulcanized tire can be removed more quickly from the vulcanization chamber or the mold.In embodiments of the invention, the cooling device has a heat exchanger with which the heat carrier can be cooled, for example with the aid of cooling water or air.In advantageous embodiments of the invention, at least one temperature sensor is integrated into the circulation line, so that temperature regulation is realized with the aid of the temperature measurement and the heating.In embodiments of the invention, at least one discharge valve is integrated into the heat transfer medium line, in corresponding embodiments for example in the region of the circulation line, with which the pressure in the heat transfer medium line can be reduced.The at least one heat carrier source is preferably connected to the heat carrier line via at least one inlet valve.Particularly preferably, the heat transfer line is connected to at least two heat transfer medium sources, which provide the heat transfer medium with a different pressure in each case. For example, a first heat carrier source with a pressure of approximately 3 bar and a second heat carrier source with a pressure of approximately 28 bar are provided. In corresponding embodiments of the invention, for example, the expansion of the bellows and the forming step can be carried out with the lower pressure, while the pressure for the vulcanization step can be adjusted to the desired higher value by means of the 28 bar heat carrier source.In embodiments of the invention, the heat carrier line is connected via at least one discharge valve to at least one outlet for the heat carrier or a heat carrier sink via which the heat carrier can be discharged after completion of the vulcanization, such that the bellows can be contracted. Preferably, however, the emptying takes place into the intermediate storage unit, so that the heat carrier can be reused.In embodiments of the invention, the heat transfer line is connected to a reduced pressure line via a valve. With the aid of such a vacuum line, the bellows and / or the circulation line can be emptied as required.The at least one heating device can preferably be connected to a tire heating press in such a way that at least one internal heating can be realized, by means of which a heat carrier can be heated to a predefined temperature and conducted through the bladder of the tire heating press, so that the tire to be vulcanized can be heated from the inside through the bladder.In embodiments of the invention, the heating device additionally comprises an external heater.In advantageous embodiments, at least one mechanical safety valve, a flow measuring device and / or a device for checking for leaks are integrated into the heat transfer line.In embodiments of the invention, a heating device according to the invention is used as an internal and / or external heating of a tire heating press.A tire heating press according to the invention has at least one vulcanization chamber, at least one bellows and at least one heating device according to the invention.The bladder is centrally disposed in the closed vulcanization chamber and expandable such that a tire to be vulcanized is pressable from inside into a mold disposed in the vulcanization chamber.In embodiments of the invention, the mold consists of a plurality of mold segments.In embodiments of the invention, the heating device according to the invention is connected to the bladder of the tire heating press in such a way that it is connected to the heat transfer medium line, for example by forming part of the circulation line, and thus an internal heating is realized.In embodiments of the invention, the heating device according to the invention additionally implements an external heating of the tire heating press.In embodiments of the invention, the tire heating press has an after-treatment device for after-treatment of vulcanized tires, wherein the after-treatment device is connected to the at least one intermediate storage of the heating device for utilizing the intermediate stored heat carrier.A method according to the invention for producing tires with the aid of a tire heating press comprises at least the following method steps:loading a vulcanization chamber of the tire heating press with a green tire,closing the vulcanization chamber,expanding the bladder of the tire heating press by the introduction of inert gas or an inert gas-vapor mixture,vulcanization of the raw tire to form a tire,opening the vulcanization chamber,contraction of the bellows,unloading the cured tire from the curing chamber,wherein at least during the process step of vulcanization an inert gas or an inert gas-vapor mixture is introduced as heat carrier through a heat carrier line into the bellows, and wherein the heat carrier is introduced into an intermediate storage for contracting the bellows and is temporarily stored for renewed use in a subsequent process cycle or process step.In embodiments of the method according to the invention, the heat carrier temporarily stored in the intermediate store is used for the expansion and / or heating of the bellows in a next vulcanization cycle.In embodiments of the method according to the invention, at least during the process step of vulcanization, an inert gas as heat carrier is circulated through a circulation line and the bellows, wherein the inert gas is circulated and heated by means of a circulation pump and heater arranged in the circulation line outside the bellows for realizing an internal heating of the tire heating press, and wherein, in at least one further process step of tire production, the part of the circulation line connected to the bellows is bypassed by means of a bypass line, such that no inert gas is circulated through the bellows, but the heat carrier is circulated through the heater in a reservoir line formed from the remaining part of the circulation line and the bypass line by means of the circulation pump.In embodiments of the invention, the process temperature required for vulcanization is adjusted by circulating the inert gas through the heater arranged outside the bellows, wherein the inert gas is used as heat carrier.In embodiments of the invention, pure inert gas is used as heat carrier.The inert gas nitrogen is preferably used as the heat carrier.Particularly preferably, the temperature of the heat carrier is already set to a desired value before the expansion of the bellows in a reservoir, so that heat carrier of the desired temperature is available for the expansion of the bellows and the subsequent vulcanization process from the beginning.In preferred embodiments of the method according to the invention, a tire heating press according to the invention is used.Preferably, the pressure and / or the temperature of the heat carrier is controlled.An exemplary sequence of the method in a specific embodiment is described below.The inert gas is supplied into the circulation line of the heating device via an inert gas source, in particular a nitrogen source, and heated with the aid of the heater.Preferably, the heater is configured to heat nitrogen from about room temperature (-20° C.) to a temperature of up to 200° C. in one pass.The pressure and temperature are adjusted for the process steps of forming (expansion of the bladder) and vulcanization.The pressure is adjusted, for example, with the aid of a modulation valve and a pressure measuring device.Once the target pressure in the bladder is reached, the heater starts circulating the inert gas through the circulation line and the integrated line by the pump. The heat emitted by the heat carrier to the tire to be vulcanized and other heat losses are compensated for by the continuous circulation of the inert gas through the heater.This makes it possible to achieve a very uniform heat distribution in the bellows.After completion of vulcanization of the tire, the bladder is contracted, and the bypass valve and the circulation valves are switched so that circulation of the inert gas in the reservoir line is performed.The contraction of the bellows takes place by the discharge of the heat carrier into at least one intermediate store, in which the heat carrier is temporarily stored under pressure for renewed use in a subsequent process.Typical values for process pressure and temperature of the heat carrier in the various possible process steps are 105° C. at 1.5 bar in the molding step (expansion of the bellows), 200° C. at 28 bar in the vulcanization step and 50° C. at 5 bar in the optional active cooling after vulcanization. These values originate from the vulcanization process of tires with the aid of water vapor and are therefore predefined by the vapor pressure curve. Using nitrogen as the heat carrier, other temperature / pressure values can also be set.The invention makes it possible to reuse the heat carrier in the form of inert gas for heating a tire heating press. Steam and its production are likewise completely dispensed with. This means not only considerable savings from an energy point of view, but also a total avoidance of waste of water.In the drawings explained below, embodiments of the invention are illustrated by way of example. The following are shown: FIG. 1 : shows a schematic block diagram of the heating device of a tire heating press according to the invention, FIG. 2 is a schematic block diagram of a heating device connected to an aftertreatment device.The heating device ( 1) shown in FIG. 1 has a circulation line ( 2), a bypass line ( 3), a heater ( 4), a circulation pump ( 5) and a buffer ( 23).Via a connection device (18), the circulation line (2) is connected to the bladder (31) of a tire heating press in such a way that the interior of the bladder (31) is incorporated into the circulation line (2).The heating device (1) has two heat carrier sources (7), wherein a first heat carrier source (7) provides nitrogen at a pressure of 28 bar and a temperature of 20° C. and a second heat carrier source (7) provides nitrogen at a pressure of 3 bar and a temperature of 20° C. By opening the respectively assigned supply valve (21), the heat carrier selected here as nitrogen can be introduced into the circulation line (2) from the respective heat carrier source (7).The circulation line (2) can be functionally divided into two sections, wherein the sections are separated from one another by the connection points of the bypass line (3) to the circulation line (2).At least one bypass valve (13) is integrated into the bypass line (3). When the bypass valve (13) is closed, the heat medium circulates through the circulation line (2) and the bellows (21).If the bypass valve (13) is opened and the circulation valves (14), which are arranged in the part of the circulation line (2) facing the connection device (18) behind the connection points of the bypass line (3), are closed, the heat carrier circulates in the reservoir line (6) formed from the bypass line (3) and the remaining part of the circulation line (2).The circulation pump (5) and the heater (4) are arranged in the reservoir line (6), so that the heat carrier can be heated even in the case of circulation only in the reservoir line (6).The volume of the reservoir line (6) is expandable by a storage device (10) in embodiments of the invention.In embodiments of the invention, the flow in the circulation line ( 2) can be measured with the aid of a flow measuring device ( 22).If heat transfer medium is to be discharged from the heating device (1) and / or the bellows (31), this can be effected via heat transfer medium sinks (8). If a plurality of heat sinks (8) are provided, these can be designed for different pressure regions.The pressure in the circulation line ( 2) can be measured with the aid of a pressure measuring device ( 15). With the aid of at least one temperature sensor (16), the temperature can be measured at at least one point of the circulation line (2) and / or in the bellows (31).In the embodiment of the invention shown, a cooling device (17) is integrated in the circulation line (2). This is optional and serves for cooling the heat carrier.Heat carrier can be discharged from the circulation line (2) via a safety outlet (19) with the aid of a safety valve (20), if this should be necessary for safety reasons.The buffer (23), optionally two or more buffers (23), can be connected to the circulation line (2) via a valve (11) or can be separated from it.The intermediate storage device ( 23) is designed as a pressure storage device. A suitable pressure range of the pressure accumulator is, for example, 1 to 30 bar.The intermediate storage unit (23) allows the heat carrier to be emptied from the circulation line (2) and the bellows (31) into the latter, instead of removing the latter via a heat carrier sink (8) or the vacuum system (9).The heat carrier is temporarily stored in the intermediate storage (23) under a pressure.This allows reuse of the heat carrier for subsequent process cycles, in particular a subsequent vulcanization process, or for other processes of tire production.In addition to the reduced energy consumption for heating the heat carrier to the required process temperature, depending on the residual heat present in the temporarily stored heat carrier, the use of temporarily stored heat carrier also makes it possible to save the costs or the effort for purchase or the production of new heat carrier or the application of the required process pressure to the heat carrier.FIG. 2 shows a system according to the invention with an aftertreatment device ( 40). After-treatment devices (40) are used in tire manufacture after vulcanization of the tires, for example, to cool the still hot tires under controlled conditions.In certain aftertreatment devices ( 40), the vulcanized tires are pressurized from the inside. Compressed air is required for this purpose.The heat carrier from a heating device (1) according to the invention, which heat carrier is temporarily stored in a temporary storage (23), has a sufficient pressure for the after-treatment of the tires.In the embodiment of the invention shown, the aftertreatment device (40) has two aftertreatment stations (41, 42). The compressed air device ( 43) of the aftertreatment device ( 40) is connected to the at least one intermediate storage unit ( 23), such that the temporarily stored heat carrier can be used for the aftertreatment of the tires.The post-treatment pressure is adjustable in the embodiment of the invention shown by means of a modulation valve (12).

Claims

Heating device (1) for a tire heating press, having at least one heat carrier source (8) and a heat carrier line (2, 3, 6), wherein the heat carrier is designed as pure inert gas or as an inert gas-steam mixture, characterized in that the heating device (1) has at least one intermediate store (23), which is designed as a pressure store, wherein the at least one intermediate store (23) is connected via a valve (11) to the heat carrier line (2, 3, 6) in such a way that the heat carrier can be discharged from the heat carrier line (2, 3, 6) and / or the integrated heating system (31) of a connected tire heating press into the latter and can be temporarily stored in the latter.Heating device (1) according to claim 1, characterised in that the at least one intermediate storage (23) has at least one connection for connection to an after-treatment device (40), so that the temporarily stored heat carrier can be used by the after-treatment device (40).Heating device (1) according to one of claims 1 and 2, characterised in that it has at least one heater (4), at least one circulation pump (5), at least one pressure regulating device, at least one circulation line (2) and at least one bypass line (3), wherein the heating device (1) can be connected to a tyre heating press in such a way that at least one internal heater can be realized, with which a heat carrier can be heated to a predetermined temperature and conducted through the bellows (31) of the connected tyre heating press, so that the tyre to be vulcanised can be heated from the inside through the bellows (31), characterised in thatthe heater (4) and the circulation pump (5) are arranged outside the bellows (31) of a connected tyre heating press in the circulation line (2), such that the heat carrier can be circulated through the heater (4) and that the bypass line (3) is connected to the circulation line (2) in such a way that the section of the circulation line (2) which extends through the bellows (31) in a state connected to a tire heating press can be bypassed.Heating device (1) according to claim 3, characterised in that the heating (4) is designed as an electric heating.Heating device (1) according to one of claims 3 and 4, characterised in that it comprises at least one controllable bypass valve (13) and at least two controllable circulation valves (14), wherein the bypass valve (13) is arranged in the bypass line (3) such that the bypass line (3) can be opened or closed by means of the bypass valve (13), and wherein the circulation valves (14) are arranged between the connection of the bypass line (3) to the circulation line (2) and the connections of the connection device (18) for connecting the heating device (1) to the tyre heating press, such that the part of the circulation line (2) which in a connected state passes through the bellows (31) can be opened or closed by means of the circulation valves (14), while the remaining part of the circulation line (2) forms a reservoir line (6) in conjunction with the bypass line (3).Heating device (1) according to claim 5, characterised in that at least one heat medium reservoir (10) is integrated into the reservoir line (6), so that the reservoir volume is increased.Heating device (1) according to one of the preceding claims, characterized in that the heat carrier is designed as nitrogen.Heating device (1) according to one of Claims 3 to 7, characterized in that at least one cooling device (17) for cooling the heat carrier is integrated into the circulation line (2).Tyre heating press having at least one vulcanization chamber (30) and at least one bellows (31), characterized in that it has at least one heating device (1) according to one of Claims 1 to 8, the bellows (31) being connected to the heat transfer line (2, 3, 6).Method for producing tires with the aid of a tire heating press, comprising at least the following method steps: a. loading a vulcanization chamber (30) of the tire heating press with a raw tire, b. closing the vulcanization chamber (30), c. expanding the bladder (31) of the tire heating press by the introduction of inert gas, d. vulcanizing the raw tire to a tire, e. opening the vulcanization chamber (30), f. contracting the bladder (31), g. unloading the vulcanized tire from the vulcanization chamber (30), wherein at least during the process step of vulcanization an inert gas as heat carrier through a heat carrier line (2, 3, and a heat carrier, 6) is introduced into the bellows (31) and the heat carrier for contracting the bellows (31) is introduced into an intermediate storage (23) and is temporarily stored for renewed use in a subsequent process cycle or process step.Method for producing tyres according to claim 10, characterised in that the heat carrier temporarily stored in the intermediate store is used for expanding and / or heating the bellows in a next vulcanization cycle.Method for producing tyres according to one of claims 10 and 11, characterised in that, at least during the process step of vulcanisation, an inert gas as heat carrier is circulated through a circulation line (2) and the bellows (31), wherein the inert gas is circulated and heated by means of a circulation pump (5) and heater (4) arranged in the circulation line (2) outside the bellows (31) for achieving internal heating of the tyre heating press, and wherein, in at least one further process step of tyre production, the part of the circulation line (2) connected to the bellows (31) is bypassed by means of a bypass line (3), so that no inert gas is circulated through the bellows (31), but the heat carrier is circulated through the heater (4) by means of the circulation pump (5) in a reservoir line (6) formed from the remaining part of the circulation line (2) and the bypass line (3).Method for manufacturing tyres according to any one of claims 10 to 12, characterised in that nitrogen is used as the heat carrier.Method for producing tyres according to any one of claims 11 to 13, characterised in that the temperature of the inert gas is already set to a desired value before the expansion of the bellows (31) in a reservoir, so that the desired temperature is available for the expansion of the bellows (31) and the subsequent vulcanization process from the beginning of inert gas.Method for manufacturing tyres according to any one of claims 10 to 14, characterized in that a tyre heating press according to claim 9 is used.

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