Patent GB-513651-A (GB)
Title: Control means for broaching machines
IPC: B23Q5/06
Filed: 1938-03-26
Abstract: 513,651. Hydraulic machines. HERBERT, Ltd., A., LLOYD, A. H., and HUGO, L. J. March 26, 1938, No. 9335. [Class 69 (ii)] [Also in Group XXII] A hydraulic broaching machine has control means including a main valve and a by-pass circuit controlled by another valve automatically operated from the ram to vary the speed at one or more points in its travel so that the finishing operation may be carried out more slowly than the roughing operation. The cylinder 12 operates a surface broach which cuts on the downward stroke. A bar 15 moving with the ram carries cams 16, 17 coacting with a roller on a bar 18 and another cam 19 operating a bar 20. A pump 21 delivers oil past a relief valve 25 to a main valve 28 connected by a line 37 to the upper end of the ram cylinder. Another line 39 in communication with valves 30, 31 leads through a differential valve 32 to the lower end of the ram cylinder. A branch 34 from line 37 leads to a by-pass valve 33 which may be pre-set by a handle 35. Only one of the valves 30, 31 is open. If valve 31 is open the flow is along line 36 through valve 28 to the upper end of the ram, which descends at a speed depending on the opening of the by-pass 33. The differential valve is under pressure through line 39 to maintain a pressure difference on opposite sides of piston 12 and ensure steady downward ram movement. When valve 28 is reversed oil is exhausted along line 37 while the differential pressure is applied to the under face of piston 12 to produce upward movement. If valve 30 is open, then in one position of valve 28 pressure fluid passes above the piston 12 and exhausts through valve 32, lines 39, 41, valve 28 and line 29, while in the other position, oil passes through valve 30, line 39, differential valve 32 and the line 38 to raise the piston, and exhaust passes to line 29. The valve 28 is controlled by arm 42 on shaft 43 which carries an arm 44 slidable in an operating handle 45. The arm 44 is hinged to a rod 47 having notches 48, 49 coacting with a lug 50 on slide bar 18. When the latter is pushed back by one of the cams 16, 17 the lug is disengaged and the valve 28 is neutralised by its spring. In operation, the handle 45 is first lowered to move valve 28 to lower the ram. When the cam 17 leaves the bar 18, the lug 50 engages in the upper notch 48 and locks the parts. At the end of the travel, the lug is released by cam 16 and the valve returns to neutral. If the handle 45 is raised, the ram moves upwards, the lug 50 then engaging the upper notch until it is automatically disengaged to stop the upward movement. At any time the machine may be stopped by forcing handle 45 inwards whereupon a pin 52 rocks lever 53 and withdraws the lug 50 from its notch. The speed of the ram is adjusted by the valve 33 whose handle is biassed towards a setting-pin 55. For automatic speed changes during the stroke, the handle 35 is connected to a rod 57 operated from a cam 19 through bar 20 and pinion 59. Thus during downward movement, the bar 57 is raised to increase the opening of the by-pass and reduce the ram speed for the last part of the travel. If desired the speed may be similarly reduced in other parts of the travel. Specification 513,671 is referred to.