Patent GB-658078-A (GB)
Title: A molding machine and method of molding
IPC: B22C15/28
Filed: 1949-08-18
Abstract: 658,078. Moulding granular materials. OSBORN MANUFACTURING CO. Aug. 18, 1949, No. 21535. Convention date, Sept. 13, 1948. [Class 87 (ii)] [Also in Group XXII] In making articles from granular material, a unit volume of the material is projected at high velocity against a downward-facing pattern in relief or intaglio. The material is projected by a plate on which it rests and this plate follows up and rams said material. The invention is described with reference to a machine for making sand moulds in flasks which are brought into contact with a downward-facing pattern plate, but grinding wheels, cores or other articles may be produced by replacing this plate by a mould cavity facing downwardly. With the parts of the machine in the position shown in Fig. 1, a flask 11 is pushed from a roller conveyer on to rollers 49 carried by fingers 47, 48 of an arm 45 carried by a hollow plunger 39 and into alignment with a box 58 without top or bottom, held by the fingers, and with the pattern plate 8. A valve 70, Fig. 4, is operated by hand to admit compressed air by a pipe 71 into the plunger 39 whence it passes by a non- return valve 57, Fig. 10, into the cylinder 40 causing the plunger 39 &c. to rise until the flask engages the pattern plate on a fixed upper head 3. A valve 72, Fig. 4, is then operated to admit air to cylinders 17, to move them, over piston-rods 20, Fig. 1, fixed at 19 to the head 3, to the left, thus bringing a container 12 filled with sand below the flask 11, excess being struck off by a bar 38. Towards the end of this movement cams on the cylinders 17 operate a cushioning valve 26a. The movement of the valve 72 also admits air to the upper and exhausts the lower end of a cylinder 35, thus closing gate members 32, 33 of the hopper as shown in Fig. 4. A pilot valve 85 is then operated to admit air by a pipe 84 to open a spring-returned valve 80 which quickly admits a large volume of high pressure air by a pipe 79 to a chamber 69. A valve 87 is then operated to admit air by a pipe 88 to the bottom of a short cylinder 67, Fig. 2, and raise a plunger 59. As soon as its lower end 65 clears the cylinder 67, the high pressure air in 69 acts on this end 65 to lift rapidly the plunger 59 a head 61, the loose bottom 14 of the container 12, and the charge of sand which is thus compacted against the pattern plate 8. The depth of the spacer 58 is selected to allow the charge of sand to attain the necessary speed, e.g. 20-30 feet per second. The valves 85, 87 are then returned by springs or hand to exhaust position causing the plunger 59 to move down and the bottom 14 to re-engage the inturned flanges 13 of the container 12. The stroke of the plunger 59 is limited by a cross-pin 64, in a slot 63 thereof. The valve 72 is then operated to supply air to the opposite end of the cylinders 17, thus returning the container 12 to filling position. The valve 72 also exhausts the pipe 77, Fig. 4, and supplies a pipe 73 leading to a valve 74 which is opened by a projection 76 when the container 12 is directly below the hopper 31. The valve 74 admits air to the lower end of the cylinder 35, thus opening the gate members 32, 33 and filling the container 12 with sand. The valve 70 is then operated to exhaust air from the plunger 39, thus allowing the cylinder 40 to exhaust slowly via a passage in the plunger end 54, Fig. 10, partly obstructed by an enlargement 53 of a fixed rod 52. When the end 54 reaches the thin part of the rod 52 it allows a quicker exhaust, but this is again reduced by a plug 55 at the bottom of the cylinder. The lowering of the flask 11 is thus slow at both ends of its downward movement. The flask with the mould therein is moved over the rollers 49 on to a roller-conveyer at the other side of the machine and another empty flask is pushed in so that the operation can be repeated. The flask may have vents for escape of air and sand guards 62, Fig. 2, and 51, Fig. 10, may be provided. In a modification, the mould is drawn by raising the pattern instead of lowering said mould.