GB706383A - Improvements in grinding apparatus for fibrous, granular and pulverulent materials - Google Patents

Abstract

706,383 Disc mills. ASPLUND, A. J. A. July 16,1952 [July 21, 1951], No. 17969/52. Class 59 A disc-mill comprises a pulleydriven shaft 36 mounted in bearings 38, 40 to support a rotatable grinding disc 12 and adjust the grinding gap and the pressure on the material being ground between the disc 12 and a stationary disc 10, the bearings being located at one side of the discs 10, 12 between supports 22, 16 of which the latter carries the disc 12 adjustably, and the supports being connected at their base and top. The disc 10 is secured by bolts 18 to the support 16 and adjusted by further bolts 20. A casing 56 divided vertically into two parts to facilitate assembly, covers the milling zone into which material may be fed by a screw conveyer 54. The shaft 36 is moved axially by a plunger 70, Fig. 3, operated by fluid-pressure and secured to a slidable housing 48 supporting the bearing 40 and a thrust bearing 50. During a milling operation, fluid is fed to the left of the plunger along conduits 100, 106 and through a control valve 104 by a motor-driven pump 96, fluid from the opposite side of the plunger being returned through conduits 108, 112, 114 and the valve to a reservoir 92. An extension 80 of the plunger is preferably an easier fit in the bore 82 of a cylinder 72 than is the plunger in the main part of the cylinder, so that when the valve is reset by its handle 122 to feed fluid into the conduit 108 and part the grinding discs, some fluid will leak past the extension 80 into a recess 130 and back to the reservoir down a conduit 132. Movement of the disc 12 towards the disc 10 is limited by an adjustable stop screw 88 and in the cylinder 72 in the way of the extension 80. A spring-loaded arm 136 follows the extension 80 and is coupled to a gauge 144 to indicate the gap between the grinding discs. A pressure gauge 128 is located in the conduit 100 and a relief valve 126 in a branch conduit 124. A safety device, such as a diaphragm 147, is provided in the cylinder-head 78 and is such that it will burst upon a rapid increase in pressure due to the introduction of a foreign body between the discs 10, 12 and allow the fluid to escape into a conduit 148 where it operates an electric contact 160 to interrupt the feeding operation and also effects a resetting of the valve 104 by means of a conduit 150 to separate the grinding discs. In order that the valve 104 may be operated immediately fracture of the diaphragm occurs, the conduit 148 is kept full of oil from a conduit 152 provided with a cut-off valve 154 and a non-return valve 156. Specification 706,384 is referred to.