| 摘要 |
<p>872,950. Hydraulic apparatus. NORTON TOOL CO. Ltd. Sept. 21, 1959 [Oct. 1, 1958], No. 31419/58. Class 69 (2). [Also in Group XXII] A control unit for the hydraulic ram of a press, shaper, slotter, rock drill or other member, comprises an unloader valve 28 arranged to open and vent the pressure chamber 11 of the ram when a predetermined high pressure is attained and to be held open by substantially lower pressure, and a release valve 38 which can be opened to permit the unloader valve to close. The unloader valve consists of a piston 30 which is urged by an adjustable spring 31 to one end of a cylinder 29 to close a valve 35 leading from an inlet chamber 22 connected by a line 20 to the pressure chamber 11 supplied with fluid from high and low-pressure pumps 15, 16 under the control of valves 14, 17, 18, such as described in Specification 872,951. The inlet chamber 22, and hence the pressure chamber 11, can be vented to an exhaust line 19 by operation of a manuallycontrolled valve 25, and the cylinder 29 can be connected to the exhaust line by movement of the piston opening a port 37, by operation of the manually-controlled valve 38, or by an adjustable throttle 40, 41. The downward movement of the ram can be stopped at any position by opening the valve 25 and the degree of pressure on the lever 26 of the valve determines the working pressure. At the end of the stroke of the ram, pressure builds up in the chambers 11 and 22 and acts on the valve 35 which is thus opened to permit the pressure in the chambers to move the piston 30 to the right and vent the chambers through the port 37, thus automatically initiating the return stroke. At the end of the return stroke, the drop in pressure in the chambers 11, 22 permits the piston to move to the left to close the port 37 trapping fluid in a port 36 of the cylinder. Release of the trapped fluid closes the valve 35 to initiate a new stroke and this release may be effected manually by opening the valve 38 or automatically by controlled release of the fluid through the adjustable throttle 40, 41, the rate of flow through the throttle determining the duration of the dwell in the upper position; when the throttle valve is in the wide-open position, the downward stroke is effected immediately after the return stroke. The valves 25, 38 may be actuated automatically by hydraulic, electrical or mechanical means.</p> |
