Patent GB-827254-A (GB)
Title: Improvements in apparatus for the manufacture of moulded articles from pulp
IPC: D21J7/00
Filed: 1957-08-15
Abstract: 827,254. Moulding articles from pulp. DEUTSCHE FIBRIT-GESELLSCHAFT EBERS Dr. MULLER G.m.b.H. Aug. 15, 8957 [Aug. 17, 1956], No. 25802/57. Class 17(2).  Apparatus for moulding articles from aqueous pulp, comprises a wet mould 11 including a screen mould 17 the outer surface of which is surrounded by a substantially fluid tight chamber 32, a fluid exhaust conduit 21 connected to the chamber 32, an expression mould 13 in fixed relationship alongside the wet mould 11, the expression mould 13 including a perforated support form 24 having a flexible lining 23, a second fluid tight chamber 53 surrounding the outer surface of the support form 24, a wet mould pot 12 adapted to be positioned in axial alignment with the wet mould 11, the wet mould pot 12 including rim means 16, 18 adapted to make fluid tight engagement with the rim of the screen mould 17, means for passing an aqueous pulp suspension through the rim means, an expression ram 14 adapted to be positioned in axial alignment with the expression mould 13, the expression ram including a perforated mould form 41 adapted to fit within the screen mould 17 and the support form 24 with its wall in spaced relationship thereto. Means are provided for moving the wet mould pot 12 and the wet mould 11 into and out of engagement  w ith each other, and for moving the expression mould 13 and the expression ram 14 into and out of engagement, and for moving the expression mould 13 out of alignment and the wet mould 11 into alignment with the expression ram 14, and for moving the expression ram 14 and the wet mould 11 into engagement, with the mould form 41 inside and in spaced relationship with the screen mould 17, and for moving the expression ram 14 and wet mould 11  out of engagement, and means are also provided for passing a pressure fluid through a fluid conduit 55 into the fluid tight chamber 53. In operation a press table 5 is raised by means of a hydraulic piston 4 to bring the mould pot 12 into engagement with the mould 11. An aqueous pulp suspension is then introduced through a feed line 19 so as to deposit a thin coating of pulp on the inner surface of the screen mould 17. The pulp feed pressure is low at first but is later increased, building up the thickness of the wet moulded article and forcing water from the pulp through the screen to the interior of chamber 32. A partition 30 in the wet mould pot 12 prevents eddies which cause irregularities in the wall of the article. Excess pulp is removed from the interior of the. mould by introducing e.g., air under pressure through a feed line 20 containing a check valve 31. Excess moisture is forced by the compressed air through the screen 17 and out of the chamber 32 through the conduit 21. After the wet moulded article has been formed in this manner the mould pot 12 is lowered by means of the hydraulic piston 4, and trolleys 9 and 10 carrying the wet mould 11 and expression mould 13 are moved along rails 8 to the position shown in Fig. 2. A press table 7 carrying the expression ram 14 is then raised by means of a hydraulic piston 6 to locate the ram 14 inside the wet moulding 15 with a slight spacing therebetween. With the conduit 21 closed air under pressure is introduced through a conduit 22 so as to transfer the moulding 15 from the screen mould 17 to the expression ram 14. The ram 14 and table 7 are then lowered again and the trolleys 9 and 10 returned to their original position seen in Fig. 1. At this stage a small vacuum in chamber 53 holds the bag 23 firmly against the inner surface of the form 24, to provide ample clearance for the wet moulding 15 to enter the bag 23 and form 24 when the expression ram 14 is again raised by the hydraulic piston 6. Water under pressure is then admitted to the chamber 53 through the conduit 55 and causes the bag 23 to compress the wet moulding 15 against the perforated male form 41. Water squeezed from the wet mould escapes through grooves 50a in a solid core 50 of the expression ram, and out through a drain 52. The pressure in chamber 53 is then reduced to a low value sufficient to hold the moulding 15a and allow the expression ram 14 to be withdrawn. While the expression ram 14 was within the expression mould 13 the wet mould pot 12 was raised into engagement with the wet mould 11 and the next article was being formed in the screen mould 17. The expression ram 14 and wet mould pot 12 are withdrawn simultaneously so that the device reaches the starting position shown in Fig. 1 with moulding 15 in the wet mould and an expressed moulding 15a in the expression mould. A slight vacuum is next induced in the chamber 53 so that the bag 23 is pressed against the support form 24 and the moulding 15a allowed to drop on to a receiver 25. The operation may be continuous and automatically controlled in the above described sequence by means of an electro hydraulic control system. The expressed moulding 15a on the receiver 25 may be fed on a drying belt (not shown) into a drying oven but is preferably dried by means of the apparatus shown in Fig. 12. This comprises a perforated male form 29 and a female die 27 between which the moulded article is located. The perforated male form 29 is supported by a hollow metal form 57 which has grooves 46, and a perforated top 58 leading to a compressed air channel 59 and conduit 47. The grooves 46 lead to an exhaust channel 60 and conduit 61. The form 57 is heated by a gas burner 62 surrounded by a chimney 63, and the die 27 is heated by gas burners 64. In operation the expressed mouldings 15a may be dropped on to the male form 29 which is then moved to position vertically below the drying die 27 and raised e.g., by means of a hydraulic press table (not shown). A cutting ring 48 on the lower end of the form 29 is pressed tightly into the die 27 to further compress the moulded article to the desired wall thickness and shape. After drying, the ram 29 is lowered and compressed air supplied through conduit 47 blows the dry moulding off the form 29 and into the die 27 whence it soon drops. Two or three drying devices are preferably provided for each device producing moist expressed mouldings.