US 3133492 A
Description (OCR text may contain errors)
May 19, 1964 J. CZULAK ETAL PRESS 2 Shets-Sheet 1 Filed May 13, 1963 May l9, 1964 J. CZULAK ETAL PRESS My/WM s .x I" "I n o l llllllllllllllll IIIIIIII u ll II Filed May 13, 1963 United States Patent 3,133,492 PRESS Joseph Czulak, Mount Eliza, Victoria, and Norman Harry Freeman, Moorabbin, Victoria, Australia, assignors to This invention relates to the design of a novel press for the production of a pressed product of rectilinear configuration. Another aspect of the invention resides in the specific application of such a press to steps in the process for the production of cheese.
For the purpose of producing pressed products which may readily be handled it is desirable that the shape of the product of the press be rectilinear. In particular the ideal shape for such a package from the point of view of ease of handling is one having a generally rectangular cross-section. To produce a press capable of applying high pressures and having a rectangular cross-section re quires the use of massive constructional sections and is generally expensive. It is well known, of course, that the ideal shape for a pressure vessel is a sphere and the most generally employed shape approximating a sphere is one which is cylindrical and in which the ends of the cylinder are closed by domes. The object of this invention is to combine the advantages of a press capable of producing a rectilinear shaped product with the struc tural advantages of a generally cylindrical shaped pres sure vessel. A further and more specific object of one aspect of the invention is the utilization of such a press in the production of cheese.
According to this invention there is provided a press comprising an inner press chamber of rectilinear transverse cross-section and an outer shell of curvilinear transverse cross-section, a piston slidable Within the press chamber, means to apply fluid under pressure to the back of the piston to cause the piston to advance into the press chamber and to apply the pressure of that fluid also internally to the walls of the press chamber to the rear of the piston and means also to apply fluid under pressure to the space between the inner press charnber and the outer shell. There may also be provided means to evacuate the press chamber and the said space.
A press constructed as above described may be operated in a condition such that on all of the walls of the inner press chamber pressure applied to one side is substantially equalised by pressure applied to the other side so that no heavy structural loads are placed on those walls. The loads are taken by the outer shell which,
because of its curvilinear configuration, can be made from relatively light gauge material to withstand a given pressure. I v
' A press of the type above defined has been designed for the purpose of overcoming certain problems arising in the mechanisation of the cheese-making process. One
of the processes which has hitherto hampered the mechanisation of the manufacture of cheese is that known as hooping or moulding. This process will be referred to hereinafter as hooping. In the hooping process cheese-curd in granular form, or which in the case of say This process has many obvious disadvantages. First of all the production rate is limited by the number of hoops which can be supplied and handled by the factory. Secondly, each hoop has individually to be dressed. Thirdly, each hoop must be handled. Fourthly, each hoopmust be washed and fifthly, since each hoop consists of several parts a considerable amount of time must be taken in their separate assembly and disassembly during each hooping operation.
We have developed an improved cheese-making process in which curd is compressed in hoops or other moulds under the influence of pressure and a vacuum produced in the pressure vessel during the compression so as to assist in the expulsion of entrained fluids from the curd and the elimination of what are called mechanical openings in the cheese. Applying this technique and the press above described the step of hooping as it is at present known can be eliminated from the cheese making process. A press of the type described can handle a large quantity of curd to produce a large rectilinear cross-sectioned block of cheese which by the employment of the vacuum technique can be produced of uniform close texture free of mechanical openings and which can then be readily cut into individual cheeses or into convenient con sinner-sized blocks also of rectilinear cross-section which in FIGURE 1;
FIGURE 3 is a schematic side elevation of the press,
without its water and vacuum pipes, suspended from a gantry and in position for charging with curd;
FIGURE 4 is a schematic side elevation of the press as in FIGURE 3 but in position for discharging com pressed curd. The press shown in the drawings, and its operation, will now be described. An exterior cylindrical shell 1 is closed at its ends with dome-shaped doors 2, 3 which are hinged to the shellby hinges 4 and retained by locks 5. Mounted within the shell, and spaced from its interior surface, isa rectangular prismatic compression chamber, denoted generally as 6, which itself is double walled. The outer wall 7 of this chamber comprises a liquid-tight steel skin and the inner wall comprises a perforated steel sleeve 8. The outer wall 7 and the sleeve 8 are separated by a corrugated sheet metal structure 9 which is perforated with holes 9A so that there is communication throughout the entire double walled area. A network of perforated longitudinal and circumferential gussets, 10 and 11 respectively, surround the outer wall 7 and contact the interior surface of the shell 1. These gussets serve to position the chamber 6 within the shell 1 and also, as will hereinafter be explained, during part of the operation of the press will serve to transmit pressure acting on the walls of the chamber to the outer shell. The dome-shaped doors *2, 3 are also provided with gussets 12 and 13 which are perforated to allow communication throughout the spaces within the doors. The outer shell is provided with end plates 14 which prevent longitudinal movement of the outer wall 7 and the corrugated structure 9. The end plates 14 do not however prevent longitudinal movement of the perforated sleeve 8 which is free to slide within the corrugated structure 9 when either or both of the dome-shaped doors are swung to an open position.
A piston 15, which is a close fit within the sleeve 8, is connected to the door 3 by means of rubber tube 16 which is extensible to permit the piston to advance into the chamber under the influence of pressure of fluid introduced into the tube. By opening valves 17, 18 water can be introduced into the tube 16 via water inlet pipe 19 and pipe 20. Pipe 20 is also connected via valves 21, 22, 23, liquid trap 24, and valve 25 to a vacuum pump. The space 26 between the double walls of the compression chamber 6 is connected to pipe 20 by means of pipe 27 and valve 28. The spaces 29, 30, within the walls of the dome-shaped doors 2 and 3 respectively, and the space 31 between the outer shell 1 and the compression chamber 6 are interconnected by pipes 32, 33, 34, and pipe 34 is connected to pipe 20 by pipe 35.
As shown in FIGURES 3, 4, the press is suspended from a gantry 36 by means of a chain 3'7 passing over a pulley 38 and attached to each end of the press. The above described water and vacuum pipes (not shown in FIGURES 3, 4) are flexible so that the press may be pivoted to various positions for convenient loading of the curd and discharge of the resultant compressed curd.
In operation, the inside of the sleeve 3 is flrstly dressed with cheese cloth or other permeable material capable of wicking action. With the door 2 open, the press is then pivoted to take up the position shown in FIGURE 3. Curd is then charged into the sleeve 8 by means of a loading chute 59 while the piston is retracted. After charging, the door 2 is closed, the press returned to a generally horizontal position, and the chamber 6 and spaces 29, 30, 31, evacuated to a vacuum of about 20-25 inches of mercury by opening valves 25, 23, 28, 22, while valve 21 is closed. Water at atmospheric pressure is then admitted to the tube 16 by opening valves 18, 19, and the piston 15 moves forward consolidating the curd and expelling Whey and air through the perforations of the sleeve 8. At the same time the tube 16 is expanded against the inside surface of the sleeve behind the piston, thereby transmitting to the sleeve the pressure of the fluid in the tube 16. The expelled whey and air is removed by vacuum pipe 27 and the whey is retained in the liquid trap '24. After substantially all of the whey has been thus expelled from the chamber, further advance of the piston 15 builds up pressure in the curd. At this stage of the operation, the pressure of the curd and the pressure of the water in the tube 16 acting on the walls of the chamber is transmitted to the outer shell 1 by the gussets 10, 11 and the pressure acting on the inside surfaces of the doors 2, 3 is transmitted to their domeashaped outer surfaces by the gussets 12, 13.
When the pressure in the curd reaches atmospheric pressure, valve 22 is closed and valve 21 is opened so that water at atmospheric pressure is admitted to spaces 29, 30, 31. The pressure of the Water entering pipe 2% is then gradually increased causing the piston to advance further and compress the curd. Because the pressure of the Water in the spaces 29, 30, 31 is approximately equal to that of the water in the tube 16, all the water pressures in the system, and the pressure in the curd, are substantially equal so that, during this stage of the compression of the curd, the components of the chamber are in a state of relatively no load. During the compression of the curd, whey escaping through the perforations of sleeve 8 is evacuated by pipe 27 which remains subjected to a vacuum of 2025 inches of mercury.
The water pressure is gradually increased to approximately 50 p.s.i.g. at which it is then maintained for about 30 minutes. The compression of the curd is then complete and the water pressure is reduced to atmospheric pressure and the vacuum source disconnected from the chamber by closing valve 28.
To discharge the compressed curd, the door 2 is opened and the water pressure raised slightly above atmospheric pressure. The piston then extends causing the sleeve 8 and the compressed curd to be slid from the press as a unit onto a trolley as shown in FIGURE 4.
It is to be noted that water must not be admitted to spaces 29, 30, 31 until the pressure in the curd has been raised to atmospheric pressure since this would cause inwardly directed forces on the chamber which has little resistance to such forces. On the other hand the gussets 1t 11, '12, 13 will not withstand large outwardly directed forces so the pressure in the curd must not be allowed to rise very much above atmospheric pressure before it is equalised by the admission of water into the spaces 29, 3t}, 31.
From the above it will be appreciated that the compression is carried out on the curd in a condition in which the curd is subjected to a vacuum, giving a cheese which is free from voids or mechanical openings and furthermore, the compression is carried out in a rectangular cross-section compression chamber in which, due to the equalisation of pressures on each side of the walls of the chamber after an initial stage where a small unequalised pressure must be tolerated because of the evacuation of the chamber, high pressure may be generated with negligible load on the chamber walls. Thus the apparatus of this invention provides a structure in which the press may be relatively cheaply constructed and in which cheese can be formed under high pressure in large volumes of generally rectilinear form.
In the process so far described, the curd which is compressed has already been subjected to previous operations, such as cheddaring, milling and salting. It is believed that by the use of this press in the method described above, cheeses such as cheddar cheeses may be produced without the necessity for the intervening cheddaring stage and in sizes and shapes admitting readily of mechanical packaging and handling. It is believed that by the use of this press, uncheddared curd may be fed into the press and in the one compression carried out under vacuum, the curd mass can be converted into cheese.
Although the press described above has been designed for use in the production of cheese, presses according to the invention may be used whenever a pressed product of rectilinear shape is required. In most of these other cases, evacuation of the press chamber will not be necessary so that pressure equalisation may be effected throughout the entire compression and a single walled compression chamber may be used.
1. A press comprising an inner shell having walls defining an inner press chamber of rectilinear transverse cross-section and an outer shell of curvilinear transverse cross-section disposed about the inner shell to provide a space between said inner shell and said outer shell, a piston having a pressing surface and a rear surface slidable within the press chamber, means to apply fluid under pressure to the rear surface of the piston to cause the piston to advance into the press chamber and to apply the pressure of said fluid also internally to the walls of the press chamber to the rear of the piston, and means to apply fluid under pressure to the space between the inner press chamber and the outer shell.
2. A press according to claim 1, in which said inner press chamber of rectilinear transverse cross section is of rectangular transverse cross-section.
3. A press comprising an inner shell having walls defining an inner press chamber of rectilinear transverse cross-section and a substantially cylindrical outer shell disposed about the inner shell to provide a space between said inner shell and said outer shell, domed ends on said outer shell, a piston having a pressing surface and a rear surface slidable within the press chamber, means to apply fluid under pressure to the rear surface of the piston to cause the piston to advance into the press chamber and to apply the pressure of said fluid also internally to the walls of the press chamber to the rear of the piston, and means to apply fluid under pressure to the interior of the domed ends and to the space between the inner press chamber and the outer shell.
4. A press according to claim 3 in which at least one of the domed ends defines a separate compartment and means is provided to communicate this compartment with the space between the inner chamber and the outer shell.
5. A press according to claim 4 in which at least one of the domed ends is hinged to the outer shell.
6. A press according to claim 4 in which the piston is connected to one of the domed ends by means of a flexible impervious tube and means is provided to admit fluid under pressure to the tube, the tube being extensible to permit the piston to advance into the chamber under the influence of the pressure of fluid admitted to the tube.
7. A press comprising an inner shell having walls defining an inner press chamber of substantially rectangular transverse cross-section, a substantially cylindrical outer shell disposed about the inner shell to provide a space between said inner shell and said outer shell, domed ends on said outer shell, a piston having a pressing surface and a rear surface slidable within the press chamber, means to apply fluid under pressure to the rear surface of the piston to cause the piston to advance into the press chamber and to apply the pressure of said fluid also internally to the walls of the press chamber to the rear of the piston, means to apply fluid under pressure to the interior of the domed ends and to the space between the inner press chamber and the outer shell, said inner shell being double-walled and comprising a fluid-tight outer wall and an inner wall in the form of a perforated sleeve.
8. A press according to claim 7 in which the inner and outer walls of the inner shell are separated by a corrugated sheet metal structure which is perforated so that there is communication between the interior of said press chamber and the entire space within the double walls of said inner shell.
9. A press according to claim 8 in which means is provided to evacuate said press chamber, the space within the inner and outer walls of said inner shell, also the space between said inner shell and the outer shell, and the interior of each of the domed ends.
10. A press according to claim 9 in which said press chamber and the space between the inner and outer walls of said inner shell may be evacuated through a pipe which opens into the space between the inner and outer walls of the inner shell.
References Cited in the file of this patent UNITED STATES PATENTS 447,003 McGowan Feb. 24, 1891 948,258 Stadler Feb. 1, 1910 FOREIGN PATENTS 107,825 Germany Dec. 11, 1899 174,898 Sweden Apr. 4, 1961