Patent Application
20240359416
The present invention relates to tire curing presses, and more particularly to hydraulic tire curing presses and methods for curing tires.
In a tire curing press, green tire refers to an uncured state of tire which is placed in special molds where all patterns and side wall branding of the tire occurs during its curing. The mold is composed of a top half and a bottom half which are fastened within structures of the tire curing press. There are two types of tire curing presses depending on the methods to maintain the pressure on the molds, such as—namely Mechanical Tire Curing Press (MTCP) and Hydraulic Tire Curing Press (HTCP). In MTCPs, the top mold is locked onto the bottom mold mechanically by a bull gear and an internal pressure is maintained. In HTCPs, the mold is kept under pressure continuously by an individual or a plurality of hydraulic cylinder. The size, weight, and complexity of mechanical tire curing presses result in very high manufacturing, transportation, and installation costs. Hence, a great number of different hydraulic actuated tire curing presses have evolved
Some aspects of the disclosure relate to a tire curing press, including a top structure and a bottom structure. A first hollow cylinder is mounted below the bottom structure and is capable of being extended during curing and retracted post-curing of a tire. A second hollow cylinder is mounted below the bottom structure at a fixed distance from the first hollow cylinder, and is capable of being extended during curing and retracted post-curing of a tire. A first column has a lower end mounted inside a first hollow piston slidably mounted inside the first hollow cylinder. A second column has a lower end mounted inside a second hollow piston slidably mounted inside the second hollow cylinder. The top structure is capable of sliding along the first and second columns in a direction towards or away from the bottom structure. Height adjustment grooves are formed at an intermediate position on each of the first and second columns to obtain variable heights between the top and bottom structures and to accommodate different sizes of tire molds. A first lock assembly is assembled concentric to the first column above the top structure and a second lock assembly is assembled concentric to the second column above the top structure. Each of the first and second lock assemblies includes clamping plates capable of being pulled towards each other to engage with the height adjustment grooves and to lock the top structure with the first and second columns during curing. A first distance sensor determines a distance between the height adjustment grooves of the first column and the clamping plates of the first lock assembly when the first hollow cylinder is retracted post-curing of the tire. A second distance sensor determines a distance between the height adjustment grooves of the second column and the clamping plates of the second lock assembly when the second hollow cylinder is retracted post-curing of the tire. A first control means disengages the clamping plates from the height adjustment grooves of the first column when a predetermined distance is sensed by the first distance sensor. A second control means disengages the clamping plates from the height adjustment grooves of the second column when a predetermined distance is sensed by the second distance sensor.
Some other aspects of the disclosure relate to a method for vulcanizing tires using the tire curing press including: positioning an uncured tire between an upper tire mold and a lower tire mold of a tire curing press; closing the tire curing press by lowering the top structure and engaging the clamping plates of the first and second lock assemblies to the height adjustment grooves of the first and second column; creating hydraulic oil pressure along inner walls of the first and second hollow cylinders to push first and second hollow pistons downward and pull the first and second columns and the top structure downwards to squeeze the upper tire mold against the lower tire mold; pumping curing media inside the upper and lower tire molds to provide pressure and temperature to cure the tire; retracting the first and second hollow cylinders post-curing; determining a distance between the height adjustment grooves of the first column and the clamping plates of the first lock assembly; determining a distance between the height adjustment grooves of the second column and the clamping plates of the second lock assembly; actuating a first control means to disengage the clamping plates from the height adjustment grooves of the first column when a predetermined distance is sensed by the first distance sensor, and actuating a second control means to disengage the clamping plates from the height adjustment grooves of the second column when a predetermined distance is sensed by the second distance sensor.
These and other aspects will be apparent from the following detailed description. In no event, however, should this brief summary be construed to limit the claimable subject matter.
The disclosed embodiments may be better understood by referring to the figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views, further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the present invention.
In the following description, reference is made to the accompanying drawings that form a part hereof and in which various embodiments are shown by way of illustration. The drawings are not necessarily to scale. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present description. The following detailed description, therefore, is not to be taken in a limiting sense.
The present disclosure relates to a tire curing press apparatus for shaping and curing tires with a hydraulic cylinder arrangement. The tire curing press relates to a class of industrial machinery which presents an opportunity to provide heating media with high pressure such as hot water, steam or nitrogen that are internally applied into a curing bladder pushing a green (uncured) tire circumferentially outwards, towards the edges of the mold by stretching the bladder. Meanwhile, the mold is heated from outside on a top and bottom surface by heating platens. Thus, the tire takes the shape within the confines of the mold under pressure and temperature for predefined time period. Hence the apparatus has in its structure the provision to secure tire molds which forms the cured tire.
The tire curing press has provisions to support or mount auxiliary sub-assemblies that helps load, i.e. to place a green tire into the mold, and to unload, i.e., to remove the cured tire from the mold. The tire curing press apparatus is also capable of adjusting the mold height to accommodate varying range of mold sizes for curing different sizes of tires within the same tire press. One of the challenges in existing devices is that, post curing, the unlocking of the top structure lock assembly from grooves in the squeeze columns does not happen efficiently. These and other challenges are addressed by embodiments disclosed herein.
The disclosure provides a device and method for tire mold height adjustment to accommodate a varying range of mold sizes helping the user to cure different sizes of tires within the same tire curing press. The linear displacement of the top structure which holds the upper mold is done by a plurality of hydraulic cylinders, guided by guide columns having multiple height adjustment grooves to facilitate the locking of the top structure at different heights and to accommodate tire molds of different sizes. The external hydraulic pressure on the upper and lower tire molds is applied with the help of hollow squeeze cylinders which are mounted at the bottom of the guide columns. The locking/unlocking of the top structure, actuation of hollow squeeze cylinders and sensing of guide column position are done using independent hydraulic and pneumatic circuits which enables accurate positioning of the guide columns and the top structure for smooth locking and unlocking operations without causing damage to the guide columns or the locking assembly.
Different embodiments will now be discussed with reference to various schematic and exemplary illustrations in the accompanying figures.
The first and second hollow cylinders (11, 12) can be mounted on the underside of the bottom support (2) by a plurality of suitable mechanical fasteners. The first and second hollow cylinders (11, 12) can be extended during curing of the tire and retracted post-curing of the tire. In some embodiments, the first and second hollow cylinders (11, 12) can be hydraulic squeeze cylinders that can be configured to apply a substantially equal squeeze pressure to a movable platen to thereby establish a final tire curing pressure within the press cavity.
The first column (9) has a lower end mounted inside a first hollow piston (13) that can be slidably mounted inside the first hollow cylinder (11). The second column (10) has a lower end mounted inside a second hollow piston (14) that can be slidably mounted inside the second hollow cylinder (12). The first and second columns (9, 10) may be vertical cylindrical squeeze columns which connects both the top structure (1) and the bottom structure (2). The top structure (1) is capable of sliding along the first and second columns (9, 10) in a vertical direction towards or away from the bottom structure (2). The vertical sliding movement of the top structure (1) is facilitated by a first lift cylinder (3a) and a second lift cylinder (3b). The first and second lift cylinders (3a, 3b) are capable of extending and retracting to slidably move the top structure (1) along the first and second columns (9, 10) in a direction towards or away from the bottom structure (2), respectively. The lift cylinders (3a, 3b) are mounted to the bottom structure (2) at one end and have an opposite connecting rod end connected to the top structure (1) by a rod end retainer (15). The first and second lift cylinders (3a, 3b) are assembled to the bottom structure (2) at a fixed distance from each other.
The columns (9, 10) can be erected over the bottom structure (2) with a bush arrangement (22) and the base of the columns (9, 10) can be fastened with a holding means (25) by interlocking fastening grooves (9c) machined in the bottom of the columns and the rod holder (25) and fastening by a plurality of bolts and washers. The holding means (25) is also assembled to the hollow pistons (13, 14) by means of fasteners. In some cases, a first holding means (25) secures the lower end of the first column (9) with the first hollow piston (13), and a second holding means (25) secures the lower end of the second column (10) with the second hollow piston (14).
An upper tire mold (23) is fixed on an upper tire mold platen (19) and assembled to the top structure (1). A lower tire mold (24) is fixed on a lower tire mold platen (20) and assembled to the bottom structure (2). During the tire curing process, the top structure (1) is pulled downward and the upper tire mold (23) is squeezed against the lower tire mold (24) when hydraulic pressure is created in the at least two hollow cylinders (11, 12).
The top of the first and second columns (9, 10) includes a step portion (9a, 10a) to lock the top structure (1) during the fully open position of the tire curing press. Height adjustment grooves (9b, 10b) are formed at an intermediate position on each of the first and second columns (9, 10). The height adjustment grooves (9b, 10b) facilitates locking of the top structure (1) at different vertical positions to obtain variable heights between the top (1) and bottom (2) structures during closed condition of the press and to accommodate different sizes of tire molds.
The first and the second columns (9, 10) may also include a further groove between the step portion (9a, 10a) and intermediate grooves (9b, 10b) to mount a split-ring (16). The further groove may be positioned in a way to facilitate the locking of the columns (9, 10) by the split-rings (16) over the bottom structure (2), when the rod holder (25) is removed.
The open condition of the press as shown in
As best shown in
In some aspects, as shown in
As best shown in
Each of the first and second lock assemblies (4, 5) include at least one lock cylinder (6, 7) capable of being independently actuated to either engage or disengage the clamping plates (8) to/from the height adjustment grooves (9b, 10b). The lock cylinders (6, 7) in some cases may be pneumatic/hydraulic cylinders.
As shown in
Application of hydraulic pressure (28) is to prevent the upper and lower tire molds (23, 24) from opening when the curing pressure (27) is developed between the molds during curing. The curing pressure (27) developed inside the molds are often high, which can cause serious disaster if the upper and lower tire molds (23, 24) accidentally opens during the curing condition.
Referring to
In some embodiments, hydraulic and pneumatic circuits configured to enable the operation of the tire curing press during open and closed conditions of the molds. The configuration of the hydraulic and pneumatic circuits will be described with reference to
In some embodiments, the pneumatic circuit as shown in
In some embodiments, the first and second control means (46, 47) can be independently actuated to independently disengage the clamping plates (8) of the first and second lock assemblies (5, 4) from corresponding height adjustment grooves (9b, 10b) of the first and second columns (9, 10). During operation, the post-curing retraction of the first hollow cylinder (11) moves the first column (9). This movement is sensed by the first distance sensor (32), and when sufficient gap is sensed by the first distance sensor (32), the corresponding control means (46) is actuated to unlock the clamp plate (8) for that corresponding column (9). Similarly, retraction of the second hollow cylinder (12) moves the second column (10). This movement is sensed by the second distance sensor (33), and when sufficient gap is sensed by the second distance sensor (33), the corresponding control means (47) is actuated to unlock the clamp plate (8) for that corresponding column (10).
This arrangement allows to separately unlock each lock assembly (5, 4) based on the feedback received from the corresponding distance sensor (32, 33) and prevents partial unlocking or jamming of the clamp plates (8) with the grooves (9b, 10b) on each column (9, 10).
The first and second control means (46, 47) may be directional flow control valves (FCV). Such FCVs may include solenoid valves, preferably 5/2 double solenoid valves.
The operation of the tire curing press will now be explained with reference to
Upon completion of curing, the first and second hollow cylinders (11, 12) are retracted by steadily reducing the hydraulic flow using appropriate flow control valves (35,45). The distance between the height adjustment grooves (9b, 10b) of the first and second columns (9, 10) and the clamping plates (8) of the first and second lock assemblies (5, 4) are determined by using distance sensors (32, 33). When a predetermined distance is sensed by the distance sensors (32, 33) the control means (46, 47) are actuated to disengage the clamping plates (8) from the height adjustment grooves (9b, 10b) of the column (9, 10). The first and second control means (46, 47) are independently actuatable upon receiving feedback from the corresponding distances sensors (32, 33). For instance, the lock cylinders (6, 7) may be independently actuated by the control means (46, 47) to disengage the clamping plates (8) from the respective height adjustment grooves (9b, 10b).
A predetermined mold opening gap (29) is maintained between the upper tire mold (23) and the lower tire mold (24) if the hydraulic oil pressure (28) is lesser than a predetermined value by setting a stroke length S of the first and/or the second hollow pistons (13, 14) and a pitch distance P between the height adjustment grooves (9b, 10b), such that S>P.
As shown in
Further, the hydraulic circuit may include a pressure retaining means (41) arranged between the flow control valves (45, 35) and the actuation means (43) to maintain the pressure in the first and/or second hollow cylinders (11, 12). A pressure control means (40) may be arranged between the pressure retaining means (41) and the flow control valves (45, 35) to steadily reduce the pressure release during retraction of the first and/or second hollow cylinders (11, 12). In some instances, the pressure retaining means (41) may be a check valve and the pressure control means (40) may be an orifice disc. A pressure relief valve (39) is included in the hydraulic circuit as a safety valve to ensure that the pressure in the first and/or second hollow cylinders (11, 12) does not exceed a predetermined limit. The hydraulic circuit includes a backflow preventer means (44) to ensure that a backpressure does not affect the position of the first and/or second hollow cylinders (11, 12). The backflow preventer means (44) may be a check valve arranged between the flow control valves (45, 35) and the actuation means (43) to ensure that the pressure in the return lines does not affect the position of the cylinders (11, 12). Further, a pressure control valve (37) is included in the hydraulic circuit between a hydraulic pressure source (not shown) and the flow control valves (45, 35) to increase the hydraulic pressure in the first and/or second hollow cylinders (11, 12). The pressure control valve (37) may be a single solenoid poppet DC valve, for example. A backflow prevention valve (38) may be provided between the pressure control valve (37) and the flow control valves (45, 35). A pressure sensor (36) may be provided to monitor the pressure within the hydraulic circuit.
Descriptions for elements in figures should be understood to apply equally to corresponding elements in other figures, unless indicated otherwise. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations, or variations, or combinations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.
