Patent GB-652531-A (GB)
Title: Improvements in and relating to presses for compacting powder materials
Inventor: SAWYER STANLEY THOMAS
IPC: B30B15/30
Filed: 1946-04-01
Abstract: 652,531. Powder-compacting presses. MUREX, Ltd. April 1, 1946, No. 10080. [Class 87 (ii)] A press comprises a die 18, a die-charging and die-closing means D at the top of the die, a punch 6 movable upwards into the die cavity 19 to compress powder therein and subsequently to eject a powder compact therafrom, a table 10 carrying the die, means for vibrating the table, and operating mechanism actuating the following automatically-timed sequence : (a) the means D initiates the charging of the die; (b) the punch descends to suck powder into the die; (c) the table vibrates to settle the powder in the die; (d) the means D closes the die; (e) the punch rises to compress the powder; (f) the punch releases the pressure; (g) the means D opens the die; (h) the punch rises to eject the powder compact. The press shown comprises an upper fixed platen 3 which carries a pressure abutment 32, an intermediate fixed platen 1, and a lower hydraulically-operated platen 4. The table 10 supports a die bolster 17 carrying the removable die 18 (which in its formative part tapers from top to bottom, to correct shrinkage on later firing), and supports also the punch 6, the punch being secured to a composite block 8, 9 which normally rests on collars 29 threaded on a column 22 secured to a saddle piece 23 fastened by nuts 26 to punch guides 11 which depend from and are secured to the table 10. The depth of the die cavity may be adjusted by adjustment of collars 29 or of nuts 26. Springs 13 normally press the punch downwardly away from the table 10, the block 8, 9 being thereby seated on collars 29. The column 22 carries a core pin 21 which forms a hole in the article. The table 10, with its super-structure and depending parts, is raised by the platen 4 which acts through a U-shaped member 24 engaging the underside of member 9. Powder is fed from an electrically-vibrated hopper 36 through a shoot 41 and falls into a cavity 35 in a cap 31 forming part of the means D. Between the cap and the die is disposed a pressure-abutment-cum-feed-slide 30 having a die-feeding cavity 38 into which powder falls from cavity 35. Springs 34 urge the cap into contact with the slide. The slide is reciprocated horizontally by cam 45 on shaft 44, through bell-crank 48 and rod 51. Shaft 44 is rotated by electric motor 42 and carries also cams 60, 67. Operation: (1) From the position shown, slide 30 moves to the right, pushing a previouslypressed powder compact before it, and powder in cavity 38 is positioned on the raised punch. (2) A hydraulic valve 68 operated by cam 67 allows platen 4 to release punch 6, which is then depressed by its springs 13, whereupon the powder is sucked into cavity 38. (3) The slide is agitated by means of cam-track 46, and simultaneously the table 10 is repeatedly raised and allowed to fall on to platen 1 by means of cams 60, bell-cranks 64 and members 66. Cams 52 coacting with lever 54, cams 55, levers 56 and rollers 59 positively depress the table. (4) The slide moves further to the right to position its solid part 37 over the die cavity. (5) The punch 6 rises, to compress the powder against part 37 for a brief period, and then drops to release the pressure. (6) The press opens and slide 30 retracts fully to the left (position shown). (7) The punch rises to move completely through the die to eject the formed compact. The cycle is then repeated. A friction clutch 71 on shaft 44 carries a cam 77, and when the clutch is engaged by moving lever 72 this cam closes hydraulic valve 80 to provide a closed circuit in which the four-way valve 68 controls the movements of the press.