GB1067604A - Improvements relating to apparatus for grinding bricks - Google Patents

Abstract

1,067,604. Grinding bricks. INTERNATIONAL DIAMOND PRODUCTS Ltd. Feb. 17, 1965 [Feb. 20, 1964], No.6748/65. Heading B3D. [Also in Division B8] In a brick grinding machine bricks are placed by an operator O at a receiving station R or a feed conveyer 10. At transfer station T the bricks are automatically deposited in a transfer conveyer 14 which carries the bricks through a centring station C, a grinding station G and a discharge station D having a takeaway conveyer 16. The feed conveyer comprises links guided by rails 33 and passing round idler sprocket 30 and sprocket 29 driven through a gear-box from the shaft 38 of the transfer conveyer 14. Each link includes a carriage 52 pivotally mounting an arm 56 the lower end of which removably supports a tray 18. Movement of the arm is limited by a pin 64 thereon cooperating with a curved finger 62 depending from the carriage. The pin also co-operates with fixed cam rails 66, 68. The rail 66 retracts the arm 56 as it approaches the transfer station T to cause the tray 18 to register with a cradle 20 on the transfer conveyer 14. The rail 68 elevates the tray after it has deposited its brick in the cradle 20. Each tray 18 includes jaws pivoted on a crosshead 100, the lower end of each jaw carrying a tray having a bottom wall, side wall and end wall. When the jaws are in closed position, the bottom walls underlie the side edges of a brick and the end walls register with the trailing end wall of the brick; when the jaws are in opened position, the bricks fall by gravity from the tray. The jaws are urged by a spring to opened position determined by stops. Movement of the jaws is equalized by a linkage. As the open trays approach the receiving station R, rollers on the jaws enter between converging rails 154, 154 on a fixed base 155 whereby the jaws are moved to closed position to receive a brick. The jaws are releasably latched closed. When a tray arrives at transfer station T a trip finger on the underlying cradle 20 of the transfer conveyer 14 releases the latch so that the tray opens and the brick falls into the cradle. The transfer conveyer 14 is in the form of a drum comprising a pair of spaced side plates, having strengthening webs and access openings, with removable covers, and an outer cylindrical wall. The drum is mounted on a shaft 38 driven by an electric motor through a variable speed reduction gearing. Brick - receiving cradles 20 are equally spaced round the drum 14. Each cradle includes side plates, the outer edges of which are straight and support a brick so that it overhangs the plates, a leading fixed jaw and a trailing movable jaw. Each jaw comprises a pivoted jaw element having a pair of outwardly divergent members provided with resilient clamping strips. Each movable jaw is actuated by a piston and cylinder device mounted on the drum 14 and controlled by a valve. As soon as a brick has been deposited in a cradle 20 at the transfer station T a fixed control cam actuates the valve to connect one end of the cylinder to a pressure chamber in the drum shaft; the movable jaw is thus moved to clamping position, the brick being held by its upper face and leading and trailing end faces. When the cradle 20 arrives at centring station C another fixed control cam actuates the valve to disconnect the end of the cylinder from the pressure chamber; a high pressure accumulator maintains jaw pressure on the faces of the brick. The centring device 24 is carried by a shelf and comprises pivoted arms carrying centring shoes 22 provided with resilient lining strips. Movement of the arms is equalized by a pin and slot connection. The shoes are biased to open position and are closed by a jack controlled by a valve actuated by trip cams on the drum 14, there being one cam for each cradle. As the cradle arrives at the centring station C the shoes 22 are closed on the brick to centre it and thereafter open. The grinding apparatus at the station G comprises (Fig. 3) two carriages (454, 456) movable towards and away from each other on a guideway (452) by a shaft (480) having oppositely threaded portions (484, 486) and rotated by a hand wheel (490). Carriage (454) supports the shaft (460) of a grinding wheel (25) belt driven by an electric motor (M1) and carriage (456) supports the shaft (464) of a second grinding wheel (25) belt driven by an electric motor (M2). When the cradle arrives at the discharge station D a further fixed control cam actuates the valve such that the movable jaw is moved away from the fixed jaw to release the brick. The bricks are returned to the receiving station R for a second run through the machine to grind a second pair of opposite faces. New trays having dimensions which fit the changed dimensions of the bricks may be substituted for the original trays, and the spacing between the grinding wheels is altered. The pair of faces ground parallel during the first pass constitute accurate reference faces to be clamped by the jaws of the cradles 20. The bricks are then run through the machine a third time to grind the end faces.