Abstract:
In a center mechanism of a tire vulcanizing machine, including an upper clamp ring for grasping an upper opening end part of a bladder, a lower clamp ring for grasping a lower opening end part of the bladder, a hub on a side of a lower mold for supporting the lower clamp ring, a spacer connected to the hub and supported on the side of the lower mold to be ascendable and descendable, and a center post supported by the spacer to be extensible and contractible, the hub and the spacer are formed as members separate from each other, and are divisibly bound to each other by bolts.

Description:
RELATED APPLICATIONS 
     The present application is based on, and claims priority from, Japanese Application Number 2009-095613, filed Apr. 10, 2009, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     TECHNICAL FIELD 
     This invention relates to a center mechanism of a tire vulcanizing machine used in a manufacturing process of a pneumatic tire which is mounted on an automobile or the like. 
     BACKGROUND ART 
     This type of center mechanism of a tire vulcanizing machine, as shown, for example, in  FIG. 5 , has hitherto been composed of a hub portion (lower ring portion)  100   a , which a lower clamp ring for holding a lower part of a bladder (not shown) is screwed into and fixed to; a cylindrical spacer portion  100   b  connected to the hub portion  100   a  for raising and lowering the bladder and the lower clamp ring; and a guide tube  103  fixed to an inner peripheral part of a lower heating platen  102  on a base  101 , the hub portion  100   a  and the spacer portion  100   b  being fitted in the guide tube  103  so as to be ascendable and descendable. 
     Heating and pressurizing media passages  104  are formed within the hub portion  100   a , and a heating and pressurizing media supply pipe  105   a  and a heating and pressurizing media discharge pipe  105   b  are connected to the heating and pressurizing media passages  104  by screwing-in or the like. A circulation head  106  is bolted onto the upper surface of the hub portion  100   a , and a nozzle hole (not shown) of the circulation head  106  is in communication with one of the above-mentioned heating and pressurizing media passage  104 . 
     A bottom wall part of the spacer portion  100   b  is bolted to a flange  107 , and a center post cylinder  108  is upwardly passed through and supported by the flange  107 . A piston rod  108   a  of the center post cylinder  108  penetrates the above-mentioned hub portion  100   a  and circulation head  106  to be slidable in a vertical direction, and has a leading end to which an upper clamp ring for holding an upper part of the bladder (not shown) can be secured. 
     A piston rod leading end of a bead lift cylinder  109 , which has been supported upwardly by a bracket (not shown) on the base  101 , is fixed to the flange  107 . By the extending and contracting action of the bead lift cylinder  109 , the above-mentioned hub portion  100   a  and spacer portion  100   b  are allowed to ascend and descend together with the center post cylinder  108 . 
     Before vulcanization of a tire, therefore, the descending action of the hub portion  100   a  and the spacer portion  100   b  by the retracting action of the bead lift cylinder  109  together with the center post cylinder  108  positions the hub portion  100   a  and the spacer portion  100   b  onto the lower mold, while the leading end of the piston rod  108   a  protruding above the hub portion  100   a  is retracted by the center post cylinder  108 , whereby the bladder grasped by lower clamp ring and upper clamp ring is inserted along the inside surface of unvulcanized tire set on a lower mold (not shown). 
     In this state, a heating and pressurizing media are fed into the bladder from a heating and pressurizing media supply and discharge device (not shown) via the following route, heating and pressurizing media supply pipe  105   a →heating and pressurizing media passage  104 →nozzle hole of circulation head  106 , whereby the tire is vulcanized at a high temperature close to 200° C. 
     SUMMARY OF INVENTION 
     Technical Problem 
     With the above-mentioned center mechanism, the hub portion  100   a  and the spacer portion  100   b  form an integrated structure, meaning that the hub portion  100   a  and the spacer portion  100   b  are formed as separate members, and then welded together. This has posed, for example, the following problems: (1) A plurality of steps, ranging from primary machining, welding and to finishing, are needed, and each step requires due care for precision and positioning. (2) Production by manufacturers other than those well-equipped with machining devices and welding machines incurs losses in manufacturing man-hours and transportation costs, and presents a cause for deterioration in quality. (3) If a weld defect is found after welding, it cannot be repaired. (4) Since heat during vulcanization is transmitted to the hub portion  100   a , and then to the spacer portion  100   b , heat radiation becomes so great that an energy loss occurs. 
     In recent years, therefore, there has been a center mechanism, as disclosed in Patent Document 1, in which a hub and a spacer are formed as separate members, and the spacer is screwed into and bound to the hub. With this center mechanism, the problems (1) to (3) mentioned above have been resolved, but the problem (4) of energy loss has remained unsolved, and the following problem has been involved: Because of the structure in which the spacer is screwed into the hub, mounting and dismounting operations for disassembly and repair, replacement, etc. of the hub are complicated, requiring enormous time and labor. 
     That is, with such a structure that a hub is rotated at the screw thread connection, it is impossible to helically rotate the hub alone, because the lower end parts of the heating and pressurizing media supply pipe and the heating and pressurizing media discharge pipe connected on the hub penetrate the bottom wall part of the spacer, etc. Thus, if the hub is to be dismounted, for example, the hub and the spacer in the interconnected state have to be once disassembled from the base ( 101 ) and, in this state, the heating and pressurizing media supply pipe and the heating and pressurizing media discharge pipe have to be detached, whereafter the hub must be helically rotated and removed from the spacer. 
     It is an object of the present invention, therefore, to provide a center mechanism of a tire vulcanizing machine, which can achieve a decrease in man-hours and an improvement in quality and easily permits commonality of components, disassembly and repair as well as replacement. 
     Solution to Problem 
     A first aspect of the present invention for attaining the above object is a center mechanism of a tire vulcanizing machine, including an upper clamp ring for holding an upper opening end part of a bladder, a lower clamp ring for holding a lower opening end part of the bladder, a hub on a lower mold side for supporting the lower clamp ring, a spacer connected to the hub and supported on the lower mold side to be ascendable and descendable, and a center post supported by the spacer to be extendable and retractable, 
     wherein the hub and the spacer are formed as members separate from each other, and are divisibly bound to each other by bolts. 
     According to a second aspect of the present invention, a heat insulating material may be interposed between the hub and the spacer. 
     According to a third aspect of the present invention, whirl-prevention means may be provided between the hub and the spacer. 
     Advantageous Effects of Invention 
     According to the center mechanism of a tire vulcanizing machine concerned with the present invention, the center mechanism is of a segmented structure in which the hub and the spacer are formed as the separate members and bound together by the bolts. Thus, a decrease in the number of the processing steps and an improvement in the quality can be achieved, because of abolition of welding or the like strongly affecting the quality. Also, during the disassembly and repair, replacement, etc. of the hub due to wear or the like of the threaded portion upon mounting and dismounting of the lower clamp ring, when the hub is to be dismounted, for example, it suffices to loosen the bolts and pull out the hub upward. In comparison with the conventional structure requiring rotation of the hub at screw thread system, the dismounting operation is simplified, and enormous time and labor are unnecessary. For the mounting of the hub, only the reverse of the above-mentioned action is sufficient. The mounting operation is simplified, and enormous time and labor are unnecessary. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a sectional view of essential parts of a center mechanism of a tire vulcanizing machine, showing an embodiment of the present invention. 
         FIG. 2  is a plan view of  FIG. 1 . 
         FIG. 3  is an enlarged sectional view of a part A in  FIG. 1 . 
         FIG. 4  is a sectional view of the center mechanism of the tire vulcanizing machine. 
         FIG. 5  is a sectional view of essential parts of a center mechanism of a tire vulcanizing machine according an earlier technology. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A center mechanism of a tire vulcanizing machine according to the present invention will now be described in detail by an embodiment with reference to the accompanying drawings. 
     Embodiment 
       FIG. 1  is a sectional view of essential parts of the center mechanism of the tire vulcanizing machine, showing an embodiment of the present invention.  FIG. 2  is a plan view of  FIG. 1 .  FIG. 3  is an enlarged sectional view of a part A in  FIG. 1 .  FIG. 4  is a sectional view of the center mechanism of the tire vulcanizing machine. 
       FIG. 4  shows a tire T being vulcanized, and a bladder B. A base of a body frame of a tire vulcanizing machine is indicated at  1 . A lower heating platen  3  is fixed to the base  1  by bolts or the like via a heat insulating plate  2 . A lower mold  4  is fixed to the lower heating platen  3  by bolts or the like. An upper mold  5  is fixed to a bolster plate (not shown), which has been assembled in an ascendable and descendable manner to the body frame, by bolts or the like via a heat insulating plate and an upper heating platen (not shown). An upper bead ring  6  is bolted to the upper mold  5 . 
     An upper clamp ring  8  is adapted to hold an upper opening end part of the bladder B, and a clamp plate  7  is bolted to the upper clamp ring  8 , whereby the upper opening end part of the bladder B can be grasped. A lock ring  9  is bisected in a circumferential direction, and a center post (a piston rod of a cylinder  19  for extending and retracting of the center post)  10  has an upper end part integrated with the bisected lock ring  9  by bolting together with the upper clamp ring  8  being inserted. In this manner, the upper clamp ring  8  is fixed to the upper end part of the center post  10 . A sealing member is interposed between the center post  10  and the upper clamp ring  8 . 
     In  FIGS. 1 ,  2  and  4 , a lower clamp ring  12  is adapted to hold a lower opening end part of the bladder B, and a lower bead ring  11  is bolted to the lower clamp ring  12 , whereby the lower opening end part of the bladder B can be grasped. A hub (lower ring)  13  has an outer peripheral part to which the lower clamp ring  12  is fixed by screwing. A sealing member is interposed between the hub  13  and the lower clamp ring  12 . 
     An assembly  16  of a sealing member and a bushing is inserted into an inner peripheral part of the hub  13  via a cylindrical case  13   b , and is held in place by a circulation head  15  fastened to the hub  13  by a plurality of (six in the illustrated embodiment) bolts  14 . Inwardly of the assembly  16  of the sealing member and the bushing, the above-mentioned center post  10  is fitted to be ascendable and descendable. The cylindrical case  13   b  is integrated with the inner peripheral part of the hub  13  by welding. An upper end part of a heating and pressurizing media passage  13   a  provided within the hub  13  opens into the bladder B via a nozzle hole  15   a  provided in the circulation head  15 . A lower end part of the heating and pressurizing media passage  13   a  is connected to a heating and pressurizing media supply and discharge device (not shown) via a heating and pressuring media supply pipe  17   a  and a heating and pressuring media discharge pipe  17   b  fixed thereto by screwing-in or the like. 
     A cylindrical spacer  18  having a structure to be described later is integrated with the hub  13 . The center post drive cylinder  19  has a flange  19   a  provided in a vertically intermediate part of the cylinder  19 , and the flange  19   a  is bolted to a bottom wall portion  18   c  of the spacer  18 . The center post drive cylinder  19  is actuated to extend or retract the aforementioned center post (the piston rod of the center post drive cylinder  19 )  10 , thereby expanding or contracting the bladder B in the vertical direction. 
     A guide tube  20  is fastened to an inner peripheral part of the lower heating platen  3  by a plurality of (six in the illustrated embodiment) bolts  21 . The hub  13  moving integrally with the spacer  18  is fitted, in an ascendable and descendable manner, inwardly of a bushing  22  inserted into and fixed to the inner periphery of the guide tube  20 . Bead lift cylinders  23  are bolted to brackets  24  fixed to the base  1 , and upper end parts of piston rods  23   a  of the bead lift cylinders  23  are connected to a flange  25  of the above spacer  18 . The bead lift cylinders  23  are actuated to raise or lower the center post drive cylinder  19 , the spacer  18 , the hub  13 , the lower bead ring  11 , and the lower clamp ring  12 . 
     As shown in  FIG. 3 , the aforementioned hub  13  and the cylindrical spacer  18 , both made of stainless steel or the like, are bound together by a plurality of (six in the illustrated embodiment) bolts  27  via a heat insulating material  26  in the form of a ring plate. 
     The spacer  18  has a cylindrical body portion  18   a  to whose upper end part an inward flange portion  18   b  larger in thickness than the cylindrical body portion  18   a  is welded for integration, and the above-mentioned bolts  27  are screwed into the inward flange portion  18   b . A bottom wall portion  18   c  larger in thickness than the cylindrical body portion  18   a  is also integrated with a lower end part of the cylindrical body portion  18   a  by welding. The bottom wall portion  18   c  is connected to the aforementioned flange  25  and the flange  19   a  of the center post drive cylinder  19  by bolts  28   a  and  28   b , respectively (see  FIG. 1 ). 
     Between the hub  13  and the spacer  18 , two whirl-prevention pins (whirl-prevention means)  29  are interposed at positions in point symmetry while penetrating the heat insulating material  26 . In the illustrated embodiment, two slots  13   d  elongated in the radial direction are formed in the lower surface of the hub  13  around the holes through which the above-mentioned predetermined two bolts  27  are inserted (see  FIG. 2 ). In the upper surface of the inward flange portion  18   b  as well, two shallow holes  30  are formed to be located around the threaded holes, into which the above two bolts  27  are screwed, and concentrically with the threaded holes. The whirl-prevention pins  29  of a cylindrical shape penetrating the heat insulating material  26  engage both with the slots  13   d  and the shallow holes  30  while being penetrated by the above-mentioned bolts  27 . In  FIG. 3 , a threaded portion  13   c  allows the lower clamp ring  12  to be screwed thereon. 
     Before vulcanization of the tire T in the apparatus of the above-described configuration, the hub  13  and the spacer  18  descend, together with the center post cylinder  19 , by the retracting action of the bead lift cylinder  23 , whereby the unvulcanized tire T is positioned in the lower mold  4 . Also, the leading end of the center post (piston rod)  10  protruding above the hub  13  is retracted by the center post cylinder  19 , so that the bladder B grasped by the lower clamp ring  12  and the upper clamp ring  8  is inserted along the inner surface of the unvulcanized tire T set within the upper and lower molds  5  and  4 . 
     In this state, a heating and pressurizing media are fed from the heating and pressurizing media supply and discharge device (not shown) via the following route, heating and pressurizing media supply pipe  17   a →heating and pressurizing media passage  13   a →nozzle hole  15   a  of circulation head  15 , and supplied into the bladder B, whereby the tire is vulcanized at a high temperature, for example, close to 200° C. 
     After the vulcanization of the tire T is completed, the heating and pressurizing medium inside of the tire T is discharged, and then the upper mold  5  is raised. Then, the inside of the bladder B is vacuumed, and the center post drive cylinder  19  is operated to be extended, thereby raising the upper clamp ring  8 . Thus, the bladder B is collapsed in diameter and extended upward, and is stripped from the tire T. Then, the bead lift cylinder  23  is operated to be extended, thereby raising the lower bead ring  11  to push up and strip the tire T from the lower mold  4 . Whereafter the tire T is taken out of the apparatus by a publicly known means. Then, a tire T to be vulcanized next is brought in. 
     Then, the brought-in tire T is shaped, and the upper mold  5  is lowered. Upon closure of the mold, the heating and pressurizing media are fed into the tire T via the bladder B, as described above, to carry out the vulcanization step. 
     In the present embodiment, as stated above, the center mechanism is of a segmented structure in which the hub  13  and the spacer  18  are formed as the separate members and bound together by the bolts  27 . Thus, a decrease in the number of the processing steps and an improvement in the quality can be achieved, because of abolition of welding or the like strongly affecting the quality. Also, the commonality of the components can be achieved (with the vulcanizing machine having two of the molds and two of the center mechanism arranged at the left and right sides, for example, it does not matter which of the right side and the left side the hub  13  and the spacer  18  should be located on). 
     The heat insulating material  26  is interposed between the hub  13  and the spacer  18 . Thus, the heat during vulcanization at a high temperature, for example, close to 200° C. is restrained from being transferred from the hub  13  to the spacer  18 , whereby the energy loss is curtailed. Moreover, thermal adverse influence on the center post drive cylinder  19  and the bead lift cylinder  23  upon heating is avoided. On the other hand, the temperature fall of the lower bead ring  11  screwed to the threaded portion  13   c  of the hub  13  can be suppressed, and the quality of the tire is improved. 
     The hub  13  and the spacer  18  are bound together by the bolts  27 . Thus, during the disassembly and repair, replacement, etc. of the hub  13  due to wear or the like of the threaded portion  13   c  upon mounting and dismounting of the lower clamp ring  12 , when the hub  13  is to be dismounted, for example, it suffices to loosen the bolts  27  and pull out the hub  13  upward. In comparison with the conventional structure requiring turning the hub  13  due to screw thread connection system, the dismounting operation is simplified, and enormous time and labor are unnecessary. For the mounting of the hub  13 , only the reverse of the above-mentioned action is sufficient. The mounting operation is simplified, and enormous time and labor are unnecessary. 
     With the conventional structure requiring turning the hub  13  due to screw thread connection system, the lower end parts of the heating and pressurizing media supply pipe  17   a  and the heating and pressurizing media discharge pipe  17   b  connected to the hub  13  penetrate the bottom wall portion  18   c  of the spacer  18  and the flange  25 . This makes it impossible to helically turn the hub  13  alone. In dismounting the hub  13 , for example, the hub  13  and the spacer  18  in the interconnected state have to be disassembled from the base  1  and, in this state, the heating and pressurizing media supply pipe  17   a  and the heating and pressurizing media discharge pipe  17   b  have to be detached, whereafter the hub  13  must be helically turned and removed from the spacer  18 . In the present embodiment, by contrast, the hub  13  can be easily pulled out upward, together with the heating and pressurizing media supply pipe  17   a  and the heating and pressurizing media discharge pipe  17   b , with the spacer  18  being assembled to the base  1 . 
     The whirl-prevention pins  29  engaging both with the hub  13  and the spacer  18  are installed. Thus, when the lower clamp ring  12  screwed to the threaded portion  13   c  of the hub  13  is to be mounted or removed by helical turning in order to change the size of the tire T, for example, the turning of the hub  13  can be reliably prevented by the whirl-prevention pins  29 . Its turning moment acting on the bolts  27  to damage the bolts  27 , for example, can also be prevented. 
     It goes without saying that the present invention is not limited to the above embodiment, and various changes and modifications may be made without departing from the gist of the invention. For example, the number of the bolts  27  binding the hub  13  and the spacer  18  can be changed, or the spacer  18  composed of the cylindrical body portion  18   a , the inward flange portion  18   b  and the bottom wall portion  18   c  can be integrally formed. Furthermore, keys may be used instead of the whirl-prevention pins  29 . Besides, the center post  10  may be formed as a member separate from the center post drive cylinder  19 , and may be coupled to the piston rod of the cylinder  19 . 
     INDUSTRIAL APPLICABILITY 
     The center mechanism of the tire vulcanizing machine according to the present invention ensures commonality of the components. Thus, it is preferred when used in a multiple vulcanizing apparatus comprising a plurality of molds and center mechanisms arranged side by side. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  Base 
               2  Heat insulating plate 
               3  Lower heating platen 
               4  Lower mold 
               5  Upper mold 
               6  Upper bead ring 
               7  Clamp plate 
               8  Upper clamp ring 
               9  Lock ring 
               10  Center post 
               11  Lower bead ring 
               12  Lower clamp ring 
               13  Hub 
               13   a  Heating and pressurizing media passage 
               13   b  Cylindrical case 
               13   c  Threaded portion 
               13   d  Slot 
               14  Bolt 
               15  Circulation head 
               15   a  Nozzle hole 
               16  Assembly of sealing member and bushing 
               17   a  Heating and pressurizing media supply pipe 
               17   b  Heating and pressurizing media discharge pipe 
               18  Spacer 
               18   a  Cylindrical body portion 
               18   b  Inward flange portion 
               18   c  Bottom wall portion 
               19  Center post drive cylinder 
               19   a  Flange 
               20  Guide tube 
               21  Bolt 
               22  Bushing 
               23  Bead lift cylinder 
               23   a  Piston rod 
               24  Bracket 
               25  Flange 
               26  Heat insulating material 
               27  Bolt 
               28   a ,  28   b  Bolt 
               29  Whirl-prevention pin 
               30  Shallow hole 
             B Bladder 
             T Tire 
           
         
       
    
     CITATION LIST 
     Patent Literature 
     
         
         Patent Document 1: Japanese Patent 3300744