Abstract:
Disclosed herein is an apparatus for vulcanizing rubber, particularly for vulcanizing the ends of endless rubber belts. The apparatus disclosed herein is a lightweight and portable steam heated vulcanization apparatus which comprises upper and lower platens comprising hollow bodies having a rigid outer wall and a flexible inner wall and adapted to receive steam therein and transmit heat and pressure to a rubber belt placed between the flexible inner walls of the platens. A steam source is connected to the platens for delivery of steam and a plurality of connecting bolts pass through apertures in the platens and the belt material therebetween to align the platens and secure them together so as to apply pressure to the belt in combination with heat for optimal vulcanization.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to a steam vulcanizing apparatus which eliminates the need for heavy and bulky frames or complex hydraulic and pneumatic presses to apply and contain the pressure required for vulcanizing rubber. Utilizing modified steam platens adapted to receive connecting means which pierce the rubber sections being vulcanized, the present invention provides a steam vulcanizing apparatus that is sufficiently portable so as to be easily transported and used in the field for the manufacture or repair of rubber belts. 
       BACKGROUND OF THE INVENTION 
       [0002]    In order to join the two ends of a rubber belt together and in the process provide a strong joint therebetween, it is necessary to provide the proper heat and pressure simultaneously at the region of the joint which heat and pressure, when properly applied, act to vulcanize the rubber and thereby bond the belt ends together to form a joint. Often, in order to strengthen the joint, rubber cement is used as well as the addition of splice rubber so as to ensure that sufficient rubber is present at the region of the joint so as to provide a strong joint. 
         [0003]    In the prior art, various methods have been utilized in order to provide heat as well as pressure at the area of the proposed joint. For example, screw jacks, hydraulic cylinders, air cylinders, etc. have been utilized in the prior art to provide the appropriate pressure for vulcanization. Further, in order to provide the proper temperature for vulcanization, electrical heating as well as steam heating have been used. Thus, in known systems, there has always been a problem with coordinating the source of pressurization with the source of heating so as to properly vulcanize the belt ends to form a proper joint. 
         [0004]    It is desirable in pressurizing the location where the joint is to be produced to be able to uniformly pressurize the area at a pressure of between 60 and 125 psi. As noted above, one method for pressurizing the region of the splice comprises the use of screw clamps. In order to produce the required surface pressure at the area of the splice using screw clamping, it is necessary to tighten the clamp to a predetermined torque which requires expensive torque-measuring devices with the further expense incurred for paying the operator of such devices. In such an operation, a large number of screw clamps may be necessary so as to properly pressurize the entire surface area, and accordingly, it is a time consuming operation to ensure that each clamp carries its correct load. During the time that the curing of the splice takes place, it is necessary to repeatedly check each clamp so as to ensure that no relaxation of the pressure has occurred. A further problem arises from the fact that the screw clamps may only be placed along the outer edges of the belt, thus necessitating the use of transverse beams of great rigidity so as to evenly spread the pressure created by the torquing-down of the screw clamps across the surface of the splice. In order to provide sufficient rigidity in the beam so as to perform its required function, such a beam must be made quite heavy and accordingly such a beam is quite difficult to handle. 
         [0005]    A further means known in the prior art for clamping splices comprises the use of either hydraulic or pneumatic clamps. When such systems are properly used, even surface pressure applied to the belt surfaces at the region of the splice is possible, but in order to utilize this type of clamping procedure, a large variety of additional equipment is required such as pumps, compressors, hydraulic or air cylinders and the necessary hoses and other connections. In one form of air clamping, a pressurized rubber bag is used so as to evenly distribute clamping pressure over the entire surface of the splice area and so as to enable the absorption of any undulations in the surfaces thereof. The major drawback to the use of a rubber bag is that, due to the fact that the region wherein the rubber bag is utilized is also heated to high temperatures, the lifespan of such a rubber bag is extremely limited. Further, replacing such a rubber bag is extremely expensive. 
         [0006]    In order to vulcanize the area of the splice within a reasonable time, temperatures on the order of 300° to 360° Fahrenheit must be applied to the splice. The most commonly utilized source of heat in the splicing of rubber belts comprises radiation heating with electrical power. The main drawback to the use of electricity as a source of heat is that the site where the splicing is to take place must be within close proximity of a suitable power supply for the electricity or otherwise a large, expensive mobile electrical generator must be provided. Also, the heaters required to generate the temperatures required for vulcanization require significant voltage and, in most instances, the use of extremely long extension cables are necessary which results in large losses in voltage which thereby lowers the temperatures which may be provided through an electrical source. Thus, the time period for vulcanization may be significantly longer than what is preferred. 
         [0007]    As stated hereinabove, a further source of heat utilized in the vulcanization of rubber comprises the use of steam. The main limitation to the use of steam appears to be the requirement for a separate boiler arrangement so as to provide the steam. However, even steam heat requires the application of pressure evenly across the area being vulcanized. 
         [0008]    In his previous patent, U.S. Pat. No. 4,543,140, the disclosure of which is incorporated herein by reference, Applicant provided an apparatus and method for vulcanizing rubber belt splices which includes the following features: 
         [0009]    (1) A pair of opposed steam sacks are provided, each of which is made of an extremely thin metal skin which metal may preferably be stainless steel. The thickness of the metal skin is on the order of 0.030 inches. 
         [0010]    (2) Each steam sack is mounted on a frame device with the frame devices being reciprocable with respect to one another so as to enable adjustment of the spacing between the facing surfaces of the respective steam sacks. Thus, after the two ends of belt which are to be spliced together are placed between the steam sacks, the respective frames may be reciprocated so as to enable the engagement on opposite sides thereof by the opposed steam sacks. 
         [0011]    (3) A boiler is provided in conjunction with the present invention which enables water to be boiled to create sufficient steam so as to pressurize the steam sacks to the desired pressure while heating them to the desired temperature simultaneously. 
         [0012]    (4) A shut-off valve is provided in the system so that at the completion of the necessary vulcanizing time the pressurized steam may be retained within the steam sacks. The gradual cooling and condensation of the steam causes concurrent reduction in the pressure and temperature at the area of the splice to thereby allow the splice to come to a normal temperature and pressure while avoiding blistering at the region of the splice. 
         [0013]    (5) The system includes means for adjusting the pressure of the steam within the steam sacks so as to vary the temperature to which the belt splice is exposed which thereby controls the time of vulcanization. Accordingly, the system may be adjusted to accommodate to differing widths and thicknesses of belts as well as being adjustable to provide differing vulcanization times for belts of similar characteristics. 
         [0014]    However, even this apparatus requires the use of a heavy frame confining the steam sacks and belt ends being vulcanized together in order to obtain and maintain the necessary pressure on the relatively thin skin of the steam sacks across the area of the belt being vulcanized. 
         [0015]    Since belt structures often require repair on site, it would be advantageous to have a vulcanizing press which is readily portable and easy to use. Thus, there is a need for a lightweight, portable, steam vulcanizing apparatus. 
         [0016]    Various prior art devices for vulcanizing belts and similar structures are known. However, they invariably employ electrical heating together with some form of clamping apparatus which, for small applications, may be practical. For example, Serbin, U.S. Pat. No. 3,013,930, discloses an apparatus for connecting overlapped ends of a strip in which pins on an electric heating iron pass through holes in the jaws of a clamp and pierce two layers of material being joined. The pins do not perform any clamping function and are heated by the iron to melt the surrounding areas of the material being joined. The platens of the clamp structure are held closed by a spring and are indirectly heated by the iron. 
         [0017]    Ginter, et al., U.S. Pat. No. 4,376,668, discloses an apparatus and method of making v-belts in which an electrically heated iron is clamped around the ends of a belt material in which layers of splice material have been inserted. In one embodiment, nails are inserted through the ends of the belt and splice material to hold the ends together during vulcanization, but the nails provide no clamping function. 
         [0018]    German patent DE 2351047 discloses a vulcanizing press having rods between platen uprights which pierce a belt being joined. Electrically heated platens are positioned with the belt member between them. The patent discloses the lower platen as stationary and the upper platen as movable by pressure spindles or hydraulic cylinders. In addition to two uprights at the ends of the platens, the patent discloses several tie rods arranged between them. However, the disclosure of pressure spindles or hydraulic cylinders being used to move the upper platen raises a question as to the purpose of the tie rods. In any event, there is no means disclosed in this patent to permit the use of steam to provide heat or pressure for vulcanization in a portable apparatus. Furthermore, it appears that the pressure spindles or hydraulic cylinders provide the pressure while the tie rods appear to be for purposes of aligning the pieces being vulcanized. 
         [0019]    For larger applications where repairs must be completed in the field, it would be preferable to have a steam vulcanizing press which does not require a heavy clamping mechanism. 
         [0020]    Accordingly, it is a first object of the present invention to provide a lightweight portable steam vulcanizing apparatus which is simple to operate while being simple in design and assembly. 
         [0021]    It is a further object of the present invention to provide a lightweight portable steam vulcanizing device which enables the use of steam so as to provide both pressure and heat for the vulcanization process. 
         [0022]    It is a yet further object of the present invention to provide a lightweight portable steam vulcanizing device which enables the cooling of the vulcanized area without the use of additional equipment and while avoiding blistering of the splice. 
         [0023]    It is a still further object of the present invention to provide a lightweight portable steam vulcanizing device which enables a smooth transition between the original material and newly vulcanized material for esthetic purposes. It is a still further object of the present invention to provide a lightweight portable steam vulcanizing device which enables the operator thereof to vulcanize a spliced area of a rubber belt with great efficiency and economy. 
         [0024]    The foregoing objects are realized by the steam heated vulcanization apparatus of the present invention which comprises upper and lower platens comprising hollow bodies adapted to receive steam therein and transmit heat and pressure to a rubber object placed between the platens. A steam source is connected to the platens for delivery of steam and a plurality of connecting bolts pass through apertures in the platens to align the platens and secure them together so as to apply pressure to the rubber object in combination with heat. 
         [0025]    The platens of the steam heated vulcanization apparatus comprise a rigid metal outer plate, a flexible metal inner sheet, spacers between the outer plate and the inner sheet defining a steam chamber, an inlet port releasably connectable to a steam source, and a plurality of apertures through the outer plate and the inner sheet to receive connecting bolts therethrough, the apertures having seal means whereby steam is prevented from escaping from the steam chamber. 
         [0026]    These and other objects, aspects and features of the present invention will be better understood from the following specification when read in conjunction with the appended drawing figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIG. 1  shows the lightweight, portable steam vulcanizing apparatus of the present invention. 
           [0028]      FIG. 2  shows top views of the platens of the vulcanizing apparatus of the present invention. 
           [0029]      FIG. 3  shows a partial cross-section of the platens and connecting bolt and apertures according to the present invention. 
           [0030]      FIG. 4  shows a detailed cross-section of the aperture and connecting bolt combination of the present invention. 
           [0031]      FIG. 5  shows an exploded view of the vulcanizing apparatus of the present invention. 
           [0032]      FIG. 6  shows a side view of the vulcanizing platens and belt portions connected together ready for vulcanization. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0033]    Referring now to  FIG. 1 , the apparatus embodying the present invention includes a steam supply system  10  and a vulcanizing apparatus  30 . The steam supply system  10  may be provided as an integral element as shown or it may be separate from the vulcanizing apparatus  30 . 
         [0034]    The steam supply system  10  includes a boiler  11  in which is contained a predetermined amount of water. A filler port  12  including an overpressure safety release valve  13  is provided for introduction of water to the boiler  11 . The overpressure safety release valve is calibrated to open at a pressure higher than that required by the vulcanizing apparatus  30  but lower than that which would result in rupture of the boiler  11  or other components of the steam supply system  10  or the vulcanizing apparatus  30 . A pressure gauge  14  provides the operator with a visual display of the steam pressure in the boiler  11 . 
         [0035]    Heat to convert the water to steam is preferably provided by immersible electrically operated calrod heaters  15  within the boiler  11 , the heaters  15  being provided with appropriate operator actuated controls as well as a pressure switch  16  to deactivate the heaters  15  at a maximum upper pressure and reactivate them at a minimum lower pressure. For example, if the overpressure safety release valve  13  is set to release when the pressure of steam in the boiler exceeds 80 psi, the calrod pressure switch  16  would be adjusted to respond to upper and lower steam pressures below 80 psi. In this manner the steam supply system  10  is adjustable to provide steam at variable temperatures and pressures depending on the thickness of the material being vulcanized. Alternatively, for those locations where access to electricity may be limited, the boiler may be provided with a portable propane burner to heat the water and produce steam, such boilers are well known in the art to be capable of raising steam at 100 psi in approximately 5 minutes. In that case, the pressure switch  16  may operate the propane valve and igniter to control the flow of propane to the burner and its ignition based on the pressure sensed within the boiler  11 . 
         [0036]    To convey steam from the boiler  11  to the vulcanizing apparatus  30 , the boiler  11  is provided with two steam ports  17 . Communication between the steam ports  17  and the vulcanizing apparatus  30  is provided by flexible steam lines  18  which are preferably stainless steel and Teflon® braided hose. However, hoses of other materials capable of withstanding the temperature and pressure of the steam may be used. Releasable connectors  19  of any type commonly used with steam lines are provided at each end of the steam lines  18  to connect with corresponding connectors at the steam ports  17  and the vulcanizing apparatus  30 . If desired, shut-off valves  22  may be included as part of the steam ports  17  or the steam line connectors  19 . 
         [0037]    The steam supply system  10  is shown supported on a bracket  20  depending from the vulcanizing apparatus  30 . However, placement of the steam supply system  10  is not so limited and the steam supply system  10  may be placed anywhere in close proximity so long as it does not interfere with the operation of the vulcanizing apparatus  30 . 
         [0038]    The vulcanizing apparatus  30  comprises an upper platen  31  and a lower platen  32  between which is disposed a rubber belt  33  or other object to be vulcanized. Upper and lower platens  31  and  32  are each provided with a stem inlet port  34  to which are releasably connectable the steam lines  18 . Upper and lower platens are preferably rectangular in plan with the steam inlet ports located at one end thereof. Each platen has a plurality of regularly spaced apertures  35  which pass completely through the thickness of the platen, the apertures  35  being positioned at the same locations on the upper platen  31  as on the lower platen  32  so that, when the vulcanizing apparatus is in use, the apertures  35  of each platen are in alignment to enable insertion of connecting bolts  36  through both platens  31  and  32  and through the rubber belt  33  therebetween. 
         [0039]    With reference now to  FIGS. 3 and 4 , the specific structural details of the platens  31  and  32  will be explained, it being understood that the specific details of the upper and lower platens  31  and  32  are substantially identical. 
         [0040]    As seen in  FIG. 3 , each platen  31  and  32  includes an outer rigid plate  37  and an inner substantially flexible sheet  38  spaced apart from each other about 3/16″ by rod spacers  39  so as to maintain a steam chamber  40  within each platen  31  and  32 . Rod spacers  39  extend around the entire periphery of the platens  31  and  32  and, preferably, outer plate  37  and inner sheet  38  are welded to opposite sides of rod spacers  39  to form a sealed peripheral wall. Alternatively, an outer wall  41  may be welded over the edges of outer plate  37  and inner sheet  38  in which case rod spacers  39  may be simply placed inward of the wall as an extra support between outer plate  37  and inner sheet  38 , or rod spacers  39  may be eliminated. 
         [0041]    The materials used to manufacture the vulcanizing apparatus  30  may be any that can withstand the heat, pressure and moisture generated by steam. However, stainless steel is preferred. Outer rigid plate  37  is preferably 3/16″ to ½″ stainless steel plate and provides necessary rigidity and strength to the platens  31  and  32 . In contrast, inner sheet  38  is preferably 20-30 gauge stainless steel sheet, more preferably 24-28 gauge, providing a diaphragm-like, thin, flexible covering for even thermal transfer of heat from steam chamber  40  to the belt  33 . In addition, the flexible nature of inner sheet  38  allows it to closely conform to the belt  33  due to force exerted by steam under pressure in steam chamber  40 . 
         [0042]    As noted previously, apertures  35  in platens  31  and  32  permit the platens to be clamped together on each side of belt  33  by means of connecting bolts  36  which are received through aligned apertures  35  and pass through the belt  33  and nuts  49  which are threadably tightenable onto the exposed ends of bolts  36 . In order to maintain a secure steam seal, apertures  35  have a particular structure which is shown in detail in  FIG. 4 . 
         [0043]    Each aperture  35  comprises a first hole  42 , having a first diameter, in inner sheet  38  and a second hole  43 , having a second diameter, in outer plate  37 . The second diameter is larger than the first diameter and the first diameter corresponds substantially to the diameter of the shaft  44  of connecting bolts  36 . Secured to the inner surface of inner sheet  38 , preferably by welding, and coaxial with first hole  42  and extending outward therefrom through second hole  43  in outer plate  37  is a hollow cylinder  45 . The inner diameter of cylinder  45  corresponds to the diameter of first hole  42  and, therefore, to the diameter of bolt shaft  44 , while the outer diameter of cylinder  45  corresponds to the diameter of second hole  43 . A spacer ring  46  is disposed about cylinder  35  between outer plate  37  and inner sheet  38  to maintain the relative positions of outer plate  37  and inner sheet  38  when steam chamber  40  is devoid of steam. To provide a steam seal around cylinder  45  where it exits through second hole  43 , a sealing ring  47  of resilient, thermally resistant material is disposed around cylinder  45  on the outer surface of outer plate  37  and is held in place by a flange  48  secured to the outer end of cylinder  45 . Flange  48  extends peripherally outward from cylinder  45  a sufficient distance to prevent resilient sealing ring  47  from working free. It is preferred that the fit of resilient sealing ring  47  around cylinder  45  and against outer plate  37  be snug to ensure a good seal against steam loss through second hole  43  around the outside of cylinder  45 . However, it is noted that the introduction of steam pressure into steam chamber  40  will cause outer plate  37  to press against resilient sealing ring  47  thereby compressing sealing ring  47  between plate  37  and flange  48  resulting in a lateral elongation of the material of sealing ring  47  against the outside of cylinder  45  thereby improving the sealing effect of resilient sealing ring  47 . 
         [0044]    With the apparatus in accordance with the present invention having been described, the operation thereof will now be explained. First, with reference to  FIG. 5 , it is seen that a belt  33  is formed with a splice area  50  comprising thin sections  51  immediately adjacent the ends of the belt  33 . These thin sections  51  are preferably equal to one half the thickness of the belt  33 . As shown in  FIG. 5 , the platens  31  and  32  are arranged with the inner sheets  38  in facing relationship and the belt  33  splice area  50  is placed between the platens  31  and  32  with the thin sections  51  thereof aligned in stacked relationship with one another to form a half-lap joint. If desired, rubber cement may be applied between the thin sections  51  so as to enhance the vulcanization thereof. Connecting bolts  36  are inserted through the aligned apertures  35  and the aligned thin belt sections  51 , and nuts  49  are threadably attached to the ends of bolts  36  extending from lower platen  32 . Nuts  49  are tightened to draw the platens together against belt  33  with outer plate  37  serving to spread compression force evenly across the platens. If desired, thermal covers  21  may be applied over outer plates  37  of platens  31  and  32  as a safety measure and to reduce thermal loss through outer plates  37 . 
         [0045]    The following table relates the pressure of steam with its temperature at that pressure: 
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 PRESSURE OF STEAM 
                 TEMPERATURE OF 
               
               
                   
                 IN PSI 
                 STEAM IN F.° 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 60 
                 307 
               
               
                   
                 70 
                 316 
               
               
                   
                 80 
                 324 
               
               
                   
                 90 
                 331 
               
               
                   
                 100 
                 338 
               
               
                   
                 110 
                 344 
               
               
                   
                 125 
                 352 
               
               
                   
                   
               
             
          
         
       
     
         [0046]    As may be seen from Table 1, as the pressure of the steam increases, the temperature of the steam correspondingly increases and vice versa in a predictable relationship. As is known to those skilled in the art, as the pressure and temperature of the steam are increased, the vulcanization time is decreased for belts of equal configuration. It may be desirable to increase the temperature and pressure of the steam in situations where the belt is thicker than usual, or when it is desired to reduce the vulcanization time in belts of normal thickness, which is on the order of one-fourth to one-half inch thickness. 
         [0047]    Now, in step by step fashion, the operation of the present invention will be described: 
         [0048]    (1) The nuts  49  are loosened to as to enable removal of bolts  36  and separation of platens  31  and  32  a sufficient distance so as to enable the insertion therebetween of the thin belt sections  51  in their stacked relationship. After the thin sections  51  of belt  33  are suitably positioned, the bolts  36  are reinserted, piercing the stacked belt sections  51  and the nuts  49  are re-applied and tightened so as to firmly engage the platens  31  and  32  on respective sides of the belt  33  at the area of the splice. 
         [0049]    (2) The steam supply system  10  is connected to platens  31  and  32  by steam lines  18  and is activated by switching on the calrod heaters  15  or other heating means as is well known by those skilled in the art. If desired, a steam coil may be included in the lines  18  so as to enable the super heating of the steam formed through the boiling of the water. With the valves  22  in the closed position, the over pressure release valve  13  is adjusted as is well known to those skilled in the art so that it opens when the pressure in the boiler  11  exceeds the desired operating pressure for the system  10 . For example, if it is desired that the system operate at 100 psi of steam pressure, the over pressure release valve  13  is set so that if the pressure in the boiler  11  exceeds 100 psi, the valve  13  will open enabling the blowing-off of the excess pressure therethrough. At the same time, the upper and lower pressure limits for the calrod heaters are set on the calrod pressure switch  16 . 
         [0050]    (3) After the over pressure release valve  13  has been set at the desired operating level, and the calrod pressure switch  16  has been set, the valves  22  are opened to thereby enable steam to be supplied through the steam lines  18  through the steam inlet ports  34  into the steam chamber  40  of the platens  31  and  32  where the steam pressurizes the platens  31  and  32  causing the diaphragm-like inner sheet  38  of each platen to press against the adjacent surface of the belt  33  in the area of the splice. The pressure of the steam in the steam chamber  40  also presses against the outer plate forcing it against the resilient sealing rings  47  to seal around the cylinders  45 . The combination of the steam pressure in the steam chamber  40  acting against the inner sheet  38  and the connecting bolts  36  being tightened against flanges  48  and cylinders  45  on both sides of the belt  33  to clamp the belt in place between the platens creates sufficient compression against the belt  33  in the area of the splice for vulcanization such that heavy and bulky beams or clamping plates, complex hydraulic or pneumatic clamps, and the like are not required. In addition, spacing the connecting bolts  36  evenly across the area of the splice results in an even application of pressure across the area which is not possible with apparatus where clamps are limited to the outer periphery. Although the location of the apertures  35  and, consequently, the placement of the connecting bolts may vary depending on the material and thickness of the belt  33  being vulcanized, a location for the apertures in a rectangular arrangement of about 8″-10″, preferably 9″, on center allows for a steam pressure of up to about 120 psi, which, by Table 1, corresponds to a temperature of about 350° F. and is suitable for most applications. 
         [0051]    (4) After the steam chambers  40  in each platen  31  and  32  have been filled with steam and are pressurized at the desired pressure, the inlet valves  22  may be closed so as to isolate the steam within the steam chambers  40 . 
         [0052]    (5) The steam may be isolated within the steam chambers  40  through closing of the valves  22  at the beginning of the vulcanizing process or if desired, at the end of the vulcanizing process. If it is desired to isolate the steam within the steam chambers  40  at the conclusion of the vulcanizing process, the gradual cooling of the steam will result in gradual cooling and reduction in pressure at the area of the splice to thereby enable the splice to come to a normal room temperature and pressure without any blistering taking place. 
         [0053]    (6) At the conclusion of the vulcanization process, remaining pressure is released from the steam chambers  40  either through valves  22  or through simple release valves provided on platens  31  and  32 . Connecting bolts  36  are released and removed and the platens  31  and  32  are separated to permit removal of the belt  33 . It is noted that heat absorbed by the shafts  44  of connecting bolts  36  will be transmitted to the edges of the holes made in the belt  33  by connecting bolts  36  resulting in a vulcanized wall to those holes. As such, the holes left in the belt  33  by the connecting bolts  36  may be left as they are without any effect on the performance of the belt or they may be filled by a cold vulcanization process. 
         [0054]    In an alternative embodiment particularly suitable for portable and/or field use, the vulcanizing apparatus  30 , as described, is positioned at a slight incline relative to the longitudinal axis such that the steam supply system  10  is lowermost. The slight incline permits condensation to return from the steam chambers  40  to the boiler. 
         [0055]    Steam generated in the boiler  11  passes through steam lines  18  and steam inlet ports  34  into the steam chamber  40  of platens  31  and  32  thereby pressurizing the platens. Upon entering the steam chambers  40 , the steam gives up its heat to the platens  31  and  32  and condenses inside the chambers  40 . Positioning the apparatus  30  at an incline with the boiler  11  at the lower end allows the condensation to flow downward back to the boiler  11  while fresh steam flows upward. Because the generation of steam and recycling of condensation is continuous, valves  22  are not necessary. The steam lines  18  are preferably of sufficient diameter, such as ¾″, to facilitate the simultaneous flow or steam and condensation in opposite directions. Furthermore, locating the steam inlet ports  34  on the underside of each platen  31  and  32  at the lower inclined end as shown in  FIG. 1  facilitates the return of condensation to the boiler  11  as there are no internal shoulders or fittings within steam chambers  40  to interfere with the flow of condensation. 
         [0056]    In operation, the platens  31  and  32  and belt sections  51  are assembled as described and the apparatus  30  positioned at an incline with the steam supply system  10  lowermost. Because condensed steam is continuously recycled from the steam chambers  40  to the boiler  11  through steam lines  18  for reheating, the volume of water required in the boiler is small such that steam will form soon after the heaters  15  are switched on. Steam generated in the boiler  11  passes through the steam lines  18  into the steam chambers  40  and pressurizes the platens  31  and  32  as previously described. Condensed steam flows back to the boiler  11  through steam lines  18  and is re-heated in a continuous process whereby the desired temperature and pressure, preferably 316° F. at 70 psi, are maintained for the length of the vulcanization process. At the conclusion of the vulcanization process, the heaters  15  are switched off and the apparatus  30  is allowed to cool. As the temperature and pressure fall, the steam condenses and flows back to the boiler  11  at which time the platens  31  and  32  may be released and the belt  33  removed as previously described. 
         [0057]    The operation of the present invention has been described hereinabove with reference to, in particular,  FIG. 1  and  FIGS. 5 and 6 . As stated hereinabove, the preferred material for the vulcanizing apparatus, particularly the outer rigid plate  37  and the inner flexible sheet  38  are stainless steel at a thickness of approximately 3/16″ to ½″ and 0.012 to 0.035 inch, respectively. While this is the preferred configuration, it is noted that as long as the outer plate has sufficient rigidity to withstand excessive flexing while the inner sheet is sufficiently thin so as to be resilient and so as to enable the rapid transmission of the heat from the steam therethrough to the belt, any thickness and material fulfilling these criteria would be sufficient. 
         [0058]    It is to be stressed that one of the main aspects of the present invention lies in the fact that steam is an ideal fluid for the heating and pressurizing of a splice in a rubber belt which is being vulcanized thereby. Again, this is because the ideal circumstances for the vulcanization of rubber are pressures between 60 and 125 psi and temperatures of between 300° and 350° F. In this regard, steam is unique because between 60 psi and 125 psi, its temperature ranges between 307° F. and 352° F. Accordingly, applicant has taken advantage of this fact to devise a system and method of operation thereof which ideally takes advantage of these characteristics of steam so as to efficiently vulcanize rubber belt splices. 
         [0059]    It is further noted that, in order to make the present invention quite portable in nature, it is desirable that heavy and bulky beams, plates, hydraulic, pneumatic and other clamp or pressure applying mechanisms be eliminated. By fabricating the platens with a rigid outer side and a flexible inner side and using connecting bolts that pass through the platens and the belt being vulcanized, it is possible to use the steam pressure pushing against the rigid outer side to press the flexible inner side against the belt and provide sufficient pressure for vulcanization. Although the bolts  36  passing through the belt  33  and the platens  31  and  32  may apply a certain amount of pressure, their primary purpose is to secure the platens  31  and  32  together on either side of the splice area  50  and prevent steam pressure pushing against flexible inner sheet  38  from pushing the platens  31  and  32  apart. Without the bolts  36 , the steam pressure will cause the inner sheet  38  to bow outward and pressure application against belt  33  is reduced and uneven. In contrast, bolts  36  apply pressure both through the cylinders  45  and rigid outer plate  37  through the flanges  48  and resilient sealing rings  47  to hold the platens  31  and  32  together in a secure assembly such that the rigid outer plates  37  provide fixed outer walls on both sides of the belt  33  which are prevented from separating. Accordingly all of the steam pressure is directed with even force across inner flexible sheets  38  against the belt  33 . One distinct advantage of the present invention lies in the fact that the operator is only required to have one tool, to wit, a wrench for dogging down the nuts  49  about the bolts  36 . 
         [0060]    Preferably, as shown in the drawings, the steam is simultaneously introduced into the upper platen  31  and the lower platen  32 , the platens being connected to the steam supply system  10  in parallel. If desired, however, the platens  31  and  32  may be connected to the steam supply system in series with the boiler having one steam outlet which, preferably, connects through a steam line to the upper platen  31  and a connecting line between upper platen  31  and lower platen  32  for steam to flow from one platen to the other. 
         [0061]    The present invention has been described in relation to a preferred embodiment thereof. One of ordinary skill in the art, after reading the foregoing specification, may be able to affect various changes, substitutions of equivalence, modifications and other alterations without departing from the overall intent and scope of the inventive concepts disclosed herein. It is therefore intended that the invention described herein only be limited by the scope of the following claims.