Patent GB-448377-A (GB)
Title: Improvements in milling or like machines for copying or reproducing
IPC: B23Q35/18
Filed: 1934-12-05
Abstract: 448,377. Milling-machines; valves. FITZPATRICK, H. J., 94, Hope Street, Glasgow.- (Clearing Machine Corporation : 6499, West 65th Street, Chicago, U.S.A.) Dec. 5, 1934. No. 27620/35. Divided out of 448,337. [Class 83 (iii)] [See also Group XXIX] In a copying milling-machine, or a copying attachment to a boring and milling machine, of the kind in which a cutter and tracer assembly is maintained in contact with the work and pattern under the opposing actions of a unidirectional fluid pressure and a constantly acting force, a valve is controlled by the tracer to byepass some of the fluid pressure and thus vary the balance of force urging the cutter against the work in accordance with variations of the pattern. In one form, the valve body 18, Fig. 1, contains a balanced valve 23 having a flange 24 coacting with a seat 26 against which it is held by a spring 15 adjustable by means of a screwed sleeve 16. The tracer 14 is removably carried by a spindle 20 having a flange 34 which is normally maintained against a shoulder 36 in the body 18 by means of the spring 15 but may be moved back or tilted slightly by contact with the pattern. Fluid from a supply line is fed by a pipe 99 and opening 27 to a space 25 in the body 18, this pressure acting on the two flanges 21, 24, of the valve 23 to maintain it in a balanced condition. When the valve is moved to the right in Fig. 1 by the action of a protuberance on the pattern engaging the tracer, fluid is allowed to flow past the seat 26, through apertures 31, 32 in the valve and then to the sump by means of a pipe 100, thus reducing the pressure in the supply line and hence on a piston connected to the cutter, whereby a weight is allowed to withdraw the cutter from the work. When the pressure of the pattern on the tracer is relieved, the flange 24 closes against the seat 26, pressure in the supply line rises and the cutter is returned towards the work by the fluid pressure acting against the weight. Due to the valve 23 being balanced, movement of the tracer by the pattern is resisted by the compression of the spring 15 only. The shoulder 36 is adjustable in the body 18 and is locked by a nut 19b, a flexible washer 38 being held on the body by a screwed bush 37 to prevent leakage of fluid around the spindle 20. Fluid leaking past the piston 22 may proceed to the exhaust 100 by means of an aperture 35 in the valve. In a modification the valve 58, Fig. 5, replaces the valve 23 and has a shoulder 76 engaging a seating 76<1> in a liner 61 of the body 54. The spring 83 maintains the shoulder against the seat and acts between an end wall 80 of the valve and an adjustable screwed plug 84, locked by a nut 84b. An extension 86 of the cover 85 on the body protects the spring and prevents interference with the valve. When the valve is displaced to the right, fluid flows from the inlet pipe 97, past the seat 76<1> and through ports 94 in the valve to the exhaust pipe 98, annular recesses 90, 91, being provided in the bodv and liner to assist the flow. The tracer head 39, Fig. 3, consists of a rubber shell 41 on a body 40 rotatably mounted on a shank 43 by means of a ball bearing 47 and a screwed sleeve 42 held on the shank by a screw 45. The shank is adjustably connected by a screw 67, Fig. 5, and lock-nut 68 ot a ball-andsocket joint 69 on a stem 63 carrying a flanged disc 56. Oscillation or axial movement of the tracer shank 43 rocks or displaces the valve 58 through the disc 56 and thereby allows fluid to flow from pipe 97 to pipe 98 to reduce the pressure in the supply line and allow the weight to withdraw the cutter from the work. The disc 56 is pressed by the spring 83 against a shoulder 55 on an end cover 53 of the body 54 which is adjustable in the body and is looked by a nut 57. Fluid leaking past the valve drains back to the exhaust 98 through apertures 59, 59b. A tubular extension 52 of the cover 53 carries a ball race, (not shown), forming a centre bearing for the shank 43, the shank being freely slidable through the inner ball race and being balanced about it by means of an adjustable balance weight 74 locked by a screw 75. Particles of foreign matter becoming lodged between the valve and its sleeve 61 may be removed by manually rotating the valve through the shank 43 and pins 71, 87 forming loose connections between the shank and stem 63 and between the disc 56 and valve respectively. In a further modification, for use in a vertical milling machine the valve body 54a, Fig. 8, is arranged vertically and contains a valve similar to the valve 58, Fig. 5. The tracer 39a is adjustably secured to a shank 63a corresponding to the stem 63 of Fig. 5 and the supply and exhaust of fluid are at 99a and 100a respectively. Flanges are provided on the shank 63a and the end cover 109 of the body to prevent fluid from creeping along the shank and a drip tray 113 is formed on the cover 109 to receive fluid dripping from the valve. The outlet 114 from the tray 113 is connected to one of a number of holes in the tray, the remaining holes being closed by plugs 116, so that the cover may be rotated for vertical adjustment of the disc 56, Fig. 5, and the outlet re-inserted in the most appropriate hole. The body 54a is attached by bolts 120 to a slotted base 118 carrying a bar 121 mounted in a clamp head 122 of a second bar 123 which in turn is mounted in a clamp head 124 of a bracket 125 on the machine, thus enabling universal adjustments of the valve to be made. A limit stop is provided on the valves shown in Figs. 5 and 8 comprising a collar such as 106a, Fig. 8, on a rod 81 or 81a attached to the end wall 80 of the.valve. If the tracer runs off the edge of the pattern, inward feed of the tracer and cutter will cause the collar 106a to engage a fixed bracket or linkage such as 126 to cause the valve to be unseated and reduce the pressure in the supply line, thereby stopping further inward feed. Specification 448,337 is referred to.