GB489791A - Improvements in fluid pressure operated metal cutting or other machines - Google Patents

Abstract

489,791. Hydraulically - operated machine-tools. HELLER, H., and HELLER, R. March 12, 1937, No. 7260. [Class 69 (ii)] [Also in Group XXII] In a hydraulically - operated machine - tool such as a milling-machine, the rise of pressure which occurs when a moving part such as a slide reaches a stop is utilized to initiate the movement of another part, the said rise of pressure acting on auxiliary control valves which operate the main control valves which direct the fluid to the various hydraulic slideoperating cylinders. In the application to a machine for milling internal threads the cutter 1, is mounted on a carriage 3 moving transversely on a longitudinal carriage 4. The work pieces are arranged on an inclined track 6 from which they are released one by one so that they roll into a clamping sleeve 7 where they are secured by a clamping and centring pin 21. The tool is fed longitudinally and then transversely into the work which is rotated about 1 1/3 turns while the tool moves axially to give the required lead to the thread. This leaves the opening 8 of the work holder facing downwardly so that after withdrawal of the tool and the clamping centre, the work pieces drop on to a runway 9 and are discharged while the work holder is returned to its receiving position. To give the required sequence of operations a pump 11 supplies through a spring loaded valve 16, a line 12 connected to control valves F, Sp, and V. Another line 13 from the pump supplies a series of auxiliary valves A<1> ..... A<6> and a third line 14 is connected through pump 15 and relief valve 17 to the valve V. In the position shown fluid flows through line 12, valve Sp and line 18 to operate the clamping cylinder 19. When the centre 21 engages the work the pressure in line 18, 22 rises and moves valve A<2> to the right which directs fluid to the valve F and moves this valve to the left (as shown). In this position fluid flows to line 26 to the piston 27 and gives the longitudinal movement of the carriage 4 to move the tool into the work, until the carriage is arrested by a stop. Pressure now rises in the line 26 and opens a valve 28 to allow flow to a line 30 and operates the piston 31 of the transverse carriage 3, thus feeding the tool transversely into the work. At the end of this movement pressure rise in the line 30 acts through a branch 63 to shift the valve A<6>, thus directing flow to the valve V and moving it to the left. This allows flow to piston 34 to operate rack 35 and rotate the work through about 1<1>/3 revolutions to cut the thread. The longitudinal feed to give the required pitch may be effected by having a stop for the carriage 4 in the form of a helical or inclined surface which is moved in unison with the work rotation. When piston 34 completes its movement a pressure rise in pipe 37 ensues and operates valve A<1> to direct fluid to the left of valve F. This returns the transverse tool carriage by flow through line 41 and subsequent pressure rise opens valve 43 and returns the longitudinal carriage. When the starting position of the tool is reached, the pressure rise in pipe 44 acts on valve A<4> to shift valve Sp and admit pressure to the front end of clamping piston 19 thus unclamping the work which drops onto the track 9. Pressure rise in line 47 operates valve A<5> so as to shift valve V until pressure is admitted to line 51 to rotate the work holder in reverse direction to its initial position. At the lowest position of piston 34 fluid passes through piston rod passage 52 to a line 53, operating a piston 54 to release the retaining catch 55 from the next work piece and allow it to roll into the work holder. Subsequent pressure rise in line 53 operates valve A<3> to shift valve Sp and admit fluid to clamping cylinder 19 to clamp the new work piece after which the cycle is repeated.