Patent GB-1533573-A (GB)
Title: Guarding devices for hydraulically operable machines of the vertical type
IPC: F16P3/08
Filed: 1976-05-28
Abstract: 1533573 Machinery safety devices DANIELS STROUD Ltd 28 May 1976 [30 May 1975] 23701/75 Heading F2J In a guarding arrangement for an hydraulically operable machine of the vertical type such as a press or moulding machine in which a pair of vertically simultaneously oppositely movable front guards 1, 2, mounted on vertical slides, guard a trapping area 3 between a fixed lower press table and a downwardly acting movable upper press table 11, and in which in normal operational working the guards 1, 2 are moved to a fully closed position (Fig. 1) to permit a plunger 13 of a control valve 15 to extend into a slot 17 of a cam track 16 on the lower guard 2 to open the valve 15 to effect power movement of the upper press table 11 from its fully raised, i.e. open position and, in this latter i.e. fully raised position of the press table 11 the guards 1, 2 are operable to close the valve 15 and additionally lock the press table 11 against downward movement, via a pivoted scotch 18, for access by the press operator to the enlarged trapping area 3 for removal of a formed article and recharging for the next press cycle, the guarding arrangement further provides the guards 1, 2 with a safety device 24-30 to both render the press inoperative and enable the guards 1, 2 to be opened by a tool setter when the upper press table 11 is in its fully down, i.e. closed position for access to the closed trapping area for the fitting, adjustment on changing of press tools &c. in complete safety for the tool setter. As shown, the scotch 18, pivoted at pin 19, carries a cam roller 22 engageable in a cam track 23 on the upper guard 1 whereby when the press table 11 is fully opened, i.e. raised, and the guards 1, 2 are opened the scotch 18 is inwardly moved by the cam track 23 to lock under the raised press table 11, and is withdrawn therefrom, i.e. outwardly pivoted, by the cam track 23 when the guards 1, 2 are closed. The scotch 18 additionally carries an inhibiter bar 24 capable of relative vertical movement thereon within limits imposed by slots 25 and restraining pins 26, 27. Thus the additional requirement of being able to open the guards 1, 2 for tool changing or adjustment by a tool setter when the press is in its closed position is met by first moving the control valve 15 to its neutral, i.e. central inoperative position, and then manually raising the inhibiter bar 24 by a handle 28, which upward movement causes a cam track 31 on the bar 24 to operate a switch 30 to de-energize an electric motor (not shown) driving the hydraulic pumps of the press to decompress the hydraulic circuit of the press which is thus rendered inoperable. The upward movement of the bar 24 allows the pins 26, 27 to move sideways into the slot portions 25a, 25b to allow pivotal movement of the scotch 18 to enable the guards 1, 2 to be opened. Thus the operation of the press for safely changing or refitting tools (dies or moulds) is as follows. With the press table 11 fully open and the guards 1, 2, open, change or insert tools on to the lower press table after which the guards 1, 2 and the press table 11 are fully closed. The control valve 15 is then moved to its neutral position and the inhibitor bar 24 lifted to stop the press pump motor via switch 30. The guards 1, 2 may then be opened, the bar 24 being held in its lifted position, and the tools or moulds &c. bolted and/or adjusted on the lower and upper press tables. The guards 1, 2 are then closed, the inhibiter bar 24 dropping back into its original place automatically under gravity whereby the press pump motor may be restarted via switch 30. The control valve 15 may now be re-opened for upward movement of the press table 11 which, when fully open, allows the guards 1, 2 to be opened so that the press is now ready for normal operation.