Abstract:
A machine and a method to manufacture soap bars. The machine and method involve a die assembly ( 10 ) having a pair of die blocks ( 11, 12 ) which support co-operating dies ( 13, 14 ). Liquid nitrogen is delivered to the two dies ( 13, 14 ) via a throttling passage ( 18 ) to cool the soap material being formed.

Description:
TECHNICAL FIELD 
     The present invention relates to machines to manufacture soap bars. 
     BACKGROUND OF THE INVENTION 
     Soap bars are manufactured by introducing into a die a block of relatively soft material from which the soap bar is to be formed. Typically, dies are provided with cavities trough which cooling water passes to cool the dies. 
     A problem with the above mentioned machines is that the soap bars formed frequently stick to the soap die because the current method of cooling has insufficient capacity and flow rate, particularly with glycerine/translucent soap. Still further, the above mentioned machines are relatively slow due to insufficient cooing capacity. 
     OBJECT OF THE INVENTION 
     It is the object of the present invention to overcome or substantially ameliorate the above discussed disadvantages. 
     SUMMARY OF THE INVENTION 
     There is disclosed herein a method to manufacture soap bars, said method including the steps of: 
     providing a first die member; 
     providing a second die member which co-operates with the first die member to provide a die cavity; 
     locating the die members so that they are spaced by a gap; 
     delivering to said gap a block of material from which the soap bar is to be formed; 
     bringing the die members together so that said material is enclosed in the cavity formed by the die members; 
     circulating a cooling fluid through the die members to cool the material; 
     separating the die members to expose the formed soap bar; and 
     ejecting the soap bar from between the die members; and wherein 
     said cooling fluid passes from a liquid phase to a gaseous phase within the die members. 
     There is further disclosed herein a machine to manufacture soap bars, said machine including: 
     a first die member; 
     a second die member to co-operate with the first die member to provide a die cavity; 
     means supporting the die members for relative movement therebetween a first position providing the die cavity and a second position at which the die members are spaced to permit material to form a soap bar to be delivered to a position between the die members and permit removal of a formed bar of soap; and 
     ducts within the die members through which a cooling fluid is to pass, said ducts including throttling means to cause expansion of the fluid within the die members, from a liquid phase to a gaseous phase. 
     Preferably, the above machine would have the ducts including passages extending to the exterior of the die members so that the cooling fluid vents to atmospheres surrounding the die members. 
     Preferably, the cooling fluid is nitrogen. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings wherein: 
     FIG. 1 is a schematic side elevation of a die assembly to manufacture soap bars; 
     FIG. 2 is a schematic top plan view of the die assembly of FIG. 1; 
     FIG. 3 is a schematic sectioned side elevation of the die assembly of FIGS. 1 and 2 sectioned along the line  3 — 3 ; and 
     FIG. 4 is a schematic sectioned side elevation of the die assembly of FIGS. 1 and 2 sectioned along the line  4 — 4 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the accompanying drawings there is schematically depicted a die assembly  10 . The die assembly  10  includes die blocks  11  and  12  supporting co-operating dies  13  and  14 . The dies  13  and  14  co-operate to provide a die cavity,  31  within which a soap bar is formed. The die block  11  and die  13  provide a first die member  15  while the die block  12  and die  14  provide a second die member  16 . The die members  15  and  16  are mounted so that relative movement therebetween can take place, The die members  15  and  16  are moveable from the position depicted to a position in which they are spaced permitting a formed soap bar to be removed from the cavity  15  and new soap material to be delivered thereto to be formed into a soap bar. 
     The die assembly  10  includes ducts through which a cooling fluid passes to lower the temperature of the disassembly  10  to aid in forming the soap bar. The ducts includes inlet ports  17  to which a supply of liquid nitrogen is attached. The inlet ports  17  lead to narrow passages  18  which throttle the liquid nitrogen causing it to expand. The expansion of the cooling fluid from a liquid phase to a gaseous phase requires latent heat of vaporization. Accordingly, the temperature of the die members  15  and  16  is lowered. The passages  18  lead to a chamber  19  in each of the dies  13  and  14 . The gas in the chambers  19  is allowed to exhaust via outlet passages  20 . Accordingly, the cooling fluid in its gaseous phase is allowed to provide a surrounding environment in respect of the dies  13  and  14 . This aids in reducing condensation and the formation of ice on the die members  15  and  16  and in particular the dies  13  and  14 . 
     Preferably, each of the dies  13  and  14  is provided with an ejector  21  moveable from its retracted position illustrated in FIG. 4, to an extended position  22  at which it would aid in ejecting a formed soap bar from the die cavity  31 . The ejector  21  includes a stem  23  having its extremity threaded and engaged with a nut  24 . The nut  24  attaches a piston  25  to the stem  13 , which piston  25  engages a spring which urges the piston  25  to move the ejector  21  to its retracted position. 
     The piston  25  co-operates with a cylindrical surface  29  to define a chamber  27 . The chamber  27  has extending to it a passage  28 . The passage  28  is attached to a supply of the cooling fluid (such as nitrogen). When cooling fluid of sufficient pressure is delivered to the chamber  27  the ejector  21  is moved to its extended position  22  to eject the formed soap bar. The cooling fluid delivered to the chamber  27  escapes through clearances between the piston  26  and surface  29 , and the ejector  21  and associated die  13 / 14 . 
     If so required, the die assembly  10  could be housed within an enclosure  30  to aid in retaining the gaseous cooling fluid around the die assembly  10 . This would also aid in insulating the die assembly  10  to maintain its low temperature and exclude atmospheric moisture from the die assembly  10 , thereby eliminating ice on the die blocks  11  and  12 .