GB842189A - Improvements in or relating to rotary compacting machines - Google Patents

Abstract

842,189. Rotary-table tableting machines. HOLROYD & CO. Ltd., J. Jan. 1, 1959 [Dec. 14, 1957], No. 38942/57. Class 87(2). A tabulating machine comprising a rotary table having dies in which punches operate to compress material therein is adapted so that the pressure rollers associated with both the upper and lower punches are displaceable when a predetermined loading is exceeded. A pair of plates 47a, Fig. 3, are pivoted at one end on a pin 46a secured to a cross head 43, Fig. 2, and carry, in their middle, an upper pressure roller 50a and, at their other end, a pin 51a pivoted in a screwed rod 53a which can be moved vertically by a hand wheel 55a. A lower pressure roller 61a is carried at the middle of a pair of plates 57a which, by a pin 59a at one end, are linked through a connecting rod 56a with the pin 46a at the end of the plates 47a and at the other end are pivoted by pins 62a to a bracket on a hydraulic cylinder 64a. The piston 65a is connected through a rod 67a to the screwed rod 53a, the junction comprising a threaded sleeve 71a and a nut 70a, whereby the effective length of the connection may be adjusted, the setting being retained by a spring finger 72a engaging serrations on the nut 70a. Rotation of the hand wheel 55a thus raises or lowers both pressure rollers 50a, 61a whilst the preset distance between them is maintained. The fluid pressure in the cylinder 64a is maintained, through a flexible tube 73a, by a piston 75a backed by a spring 76a. The machine, Fig. 2, has two sets of pressure rollers and serves to fill each die 16 and to compress the material therein twice in each revolution of the table 14. As an empty die 16 approaches a filling shoe 40 a cam track 37 raises the upper punch 35 and the lower punch 28 rests in its lowermost position on a bed 11. The die is filled with material as it passes under the shoe 40. The lower punch 28 passes on to a cam track 30 which can be adjusted by a wedge 31 to bring the punch up in the die to a predetermined position when excess material can be ejected back into the filling shoe 40. The lower punch then retracts taking with it the material remaining in the die. Thereafter, the cam track 37 causes the upper punch 35 to be lowered on to the material in the die 16, and the table continues to rotate, moving the die 16 and punches 35, 28 so that these punches pass between the upper and lower pressure rollers 50a, 61a engaging with the latter by their heads 36, 29 respectively. The rollers 50a, 61a then force the punches towards each other under a pressure as defined by that in the hydraulic cylinder 64a, and the material in the die 16 is compressed to form the tablet. After the die and punches have passed the pressure rollers, the cam track 37 raises the upper punch 35 completely clear of the die 16, whereafter the lower punch 28 engages the cam track 30 which raises it so that the compressed tablet is deflected, by an inclined guide, (not shown) laterally outwards of the die table 14, and falls into a delivery slide 81. As the die 16 then passes towards the second feed shoe 40, the cam track 30 lowers the lower punch 28 to its lowermost position, and when the die 16 reaches the second feed shoe 40 the sequence of operations recommences. Under normal loading of the punches, the framework, under the influence of the hydraulic cylinders, acts to resist any separational movement of the rollers and their mountings. However, should overloading occur, the pistons or cylinders can move to permit either or both roller mounting to move, thus relieving overload from either or both punches. Pneumatic, spring or other means may be used in place of hydraulic arrangements, or a hydrualic cylinder and accumulator may be used.