Patent GB-450873-A (GB)
Title: Improvements in or relating to broaching machines
IPC: B23Q5/06
Filed: 1935-01-28
Abstract: 450,873. Hydraulic broaching-machines. KING, T. ST. P. C., c/o Lapointe Machine Tool Co., Ltd., Edgware, Middlesex. Jan. 28, 1935, No. 2810. [Class 83 (iii)] A double-acting hydraulic broaching - machine has a variable-pressure pump which supplies the two ram cylinders 1, 2, and also supplies a work - holding device whose movements are in timed relation with the ram movements. The two rams 3, 4 are connected to broaching slides 5, 6 which are drawn downwards on their working strokes. A variable delivery pump 9 draws fluid from a reservoir 36 and discharges to a main valve 11 having a central sliding part provided with piston elements 12a .. 12<d>. The valve spindle 12 is connected to an operating lever 13 and to a rocking lever 15 having arms 17, 18 adapted to coact with the ends of a work slide 19 and lock the slide against movement. The valve chamber 24 leads through pipe 28 to the upper end of cylinder 2 and a branch 30 from this line leads through valve 31 to a pipe 29 connecting the bases of the two cylinders and connected through relief valve 32 to the exhaust line 34, which has a branch 85 which byepasses some of the exhaust fluid to lubricate and cool the pump. The work slide 19 is controlled by a valve 40 operated by a spindle 44 connected through a lever 45 to a sliding rod 47 carrying collars 67, 68 operated at the ends of the stroke by a projection 69 on the ram slide. The line 57 leading to valve 40 is supplied from the port 79 of the main valve through a shut-off valve 77 and parallel lines 80, 81, the former including valves 73, 74 and the latter valves 72, 75. These valves are operated by cams 70, 71 on the slides 5, 6 respectively. The slides 5, 6 also carry projections 84, 86 coacting at the downward end of the stroke with the lever arms 17, 18 to neutralize the main valve. A relief valve is located at 76. In operation, the rams are first synchronized by admitting oil to the line 28, the valve 31 being slightly opened and the main valve positioned as in Fig. 1. This moves the ram 4 down and the ram 3 upward to the extreme positions, after which surplus oil passes through relief valve 32. Valve 31 is then closed. As the ram 4 reaches its lowest position the projection 84 acts to restore the main valve to a neutral position wherein the pump discharge flows through port 26 back to the reservoir. At this point the cams 70, 71 have opened valves 72, 75 and the projection 69 has moved valve 40 downwards so that oil flows through pipe 57 and to the right - hand end of cylinder 52 to move the work table to the left beneath the slide 5, Fig. 3. The lever 13 can then be rocked to move the lever 15 so that the arm 18 engages behind the slide and also to move the spindle 12 to the right, thus allowing oil to flow to the upper end of cylinder 1 for a working stroke, the exhaust oil from this cylinder serving to return the ram 4. The valve 76 provides sufficient back pressure to prevent pulsation and also provides pressure to operate the cylinder 52. When the rams move, the valves 72, 75 are automatically closed, thus locking the cylinder 52. At the end of down stroke of ram 3 the main valve is again moved to neutral position the valves 73, 74 are opened and the valve 40 is operated by projection 69 to move the work table to the right beneath the slide 6. The lever 13 is then moved to the left to lock the work slide by the lever arm 17 and to shift the valve to operate the ram 4 and complete the cycle. If the worktable movement is not required the valve 77 is closed. In a machine embodiment the operating lever 13 is connected to the rod 47 so that the valve 40 may be operated manually if required. The pump is driven directly by an electric motor.