Patent GB-540683-A (GB)
Title: Control gear for hydraulically operated machines
IPC: B23Q5/033
Filed: 1940-03-20
Abstract: 540,683. Hydraulic machines. OLAH, G. March 20, 1940, No. 5159. [Class 69 (ii)] [Also in Group XXII] Control mechanism for a hydraulically-operated capstan lathe or other machine has a plurality of hydraulically-operated units such as a capstan slide, cross slide &c. each having a hydraulic pilot device which when the unit reaches a predetermined stage of the operation transmits an hydraulic impulse to the main valve of a succeeding unit to ensure a predetermined cycle of operations. Impulse selectors are interposed in the pilot conduits between the pilots and the valves to be actuated and an operation selector enables various cycles to be performed. The speed of any movement is controlled by throttling devices which are interposed by a speed selector, in the various motor circuits. In the form shown a lathe has hydraulic operation of the following elements: Capstan slide, two cross slides, work spindle reverser and stock feed device and chucking device. In Fig. 1 the permanent valve connections to pressure are indicated by the reference X and connections to exhaust by reference O. The hydraulic supply has a viscosity regulator P2 operating as described in Specification 540,684. The capstan slide is operated by a motor AM and the speed for each of the six positions is controlled by throttles Am1 ...Am6, which are put successively in circuit by mechanism operated from the slide movement. The motor supply is controlled by a valve AR actuated by a pilot valve At. A quick feed bypass Aq, synchronizer valve As and relay valve Av operate as described in Specification 540,684 and a screen circuit as described in Specifications 540,719 and 540,720 may also be provided. The control valve AR alternatively connects the front of the motor piston to pressure and exhaust, the back of the piston being permanently connected to pressure through the feed stabilizer. In the position shown in Fig. 2 the chamber 6 is open to pressure through line 9a and port 10 is connected through relay valve Av to exhaust, giving the quick return of the capstan slide. At the end of this movement the slide engages projection 3 and moves the valve to the right and stops motor AM. If now the chamber 6 is connected to high pressure by the pilot the piston 2 remains at rest but if to a low pressure the piston moves to its extreme right position thus completing the reversal and connecting port 12 to pressure so that motor AM is started forwards by supply through one of the metering throttles and the quick feed valve Aq. The reversal from capstan return to forward motion thus depends on two impulses, a mechanical impulse on projection 3 and a hydraulic impulse in chamber 6. The capstan slide is associated with pilot devices At, AT. The former, Fig. 2, has an " impulse " port 21 which is selectively connectible to pressure port 22 or exhaust port 20. The pilot AT is of similar construction and controls the feed stabilizing valve AV this valve and the synchronizer As acting as described in Specification 540,684. The impulses which control valve AR and pilots At and AT are controlled by rotary selectors actuated by pawl devices which give two selector positions per station one corresponding to most of the forward and return slide motion and the other to the withdrawn position of the capstan slide. The impulse selector is also coupled to the speed selector which, on successive forward strokes, successively interposes the adjustable metering throttles into the flow to the motor AM to regulate the working speeds for each operation. The feed of cross slide B actuated by a motor BM is controlled as described in Specification 540,719. The main valve BR of this circuit, Fig. 3, when in the position shown admits fluid for the quick return of motor BM. If pressure is admitted to chamber 261 the valve is moved against a spring 31 and pressure fluid passes through valve Bq and throttle Bm for the forward stroke of the slide. The quick feed bypass is put out of action at a predetermined point in the stroke by a projection on the slide thus giving the slow throttled working feed. The valve BT is coupled to a feed stabilizer. The pilot Bt is operated against a spring 23 by a projection on the slide and has a line connected to a selector Bs which is connected at 39 to the quick feed valve. The hydraulic equipment of the second cross slide may be the same as that for cross slide B. The reverse coupling for the work spindle is actuated by motor DM controlled by a spring returned reversing valve. The stock feed motor EM is controlled by a spring returned valve ER and operates a pilot valve ET. The chucking motor FM is started and reversed by a valve FR actuated in one direction mechanically and in the other direction by a high pressure impulse. Time delay throttles AR1...AR6 are inserted in the impulse conduits which effect the re-starting of the capstan slide only after a suitable time delay. In order to obtain a predetermined sequence of operations an operation selector controls the connections between the impulse or pilot valves and the various main valves. Such a selector is shown in Fig. 5, 56 being a base plate connected with the impulse selector housing and having channels 61 corresponding to conduits AR1...AR6, AT1...AT6 &c. in Fig. 1. A cover plate 57 has channels 60 corresponding to horizontal conduits AT, At &c. in Fig. 1. An exchangeable interposed disc 58 establishes the required connections between channels 60 and 61, the disc being changed for different operational sequences. Modifications of the operation selector are also described. In an example given in the Specification, the following sequence of operations is performed. (1) and (2) Turning operations with capstan slide. (2a) Turning with cross slide B. (3) Drilling with capstan slide. (4) Threading cutting operation of capstan slide with a running-off die head. (5) Second thread cutting operation with a selfopening die head (5a) Cutting off by cross slide C (not shown), is established by the disc 58 in Fig. 5 and the hydraulic connections corresponding to the operations 1 ... 6 above are described in detail in the Specification. During the thread cutting operations, the motions of the spindle and capstan slide are synchronized as described in Specification 540,720. The invention may be applied to a machine having additional hydraulically operated units. In a modification, Fig. 8, a capstan lathe has a single cross slide which performs a forming operation in both directions of movement and the stock feed is gravity operated. Instead of a synchronizing device for thread cutting it is arranged that the forward and return speeds of the slide when using a running- off die are in the same ratio as the forward and reverse work spindle speeds. In order to reduce the consumption of high pressure fluid the motors may be of the differential piston type. The pump P delivers its surface output to a low pressure accumulator L. The valves, pilots and selector elements are actuated by low pressure fluid and the rotary impulse selector and the operation selector are combined in a single mechanically actuated unit. A single throttle is employed and the speeds for different phases are varied by mechanically operated throttle-setting devices. The three-chambers turret-operating cylinder has a part A connected to high pressure for the working and low pressure for return motions, and a part C connected for forward working feed through a stabilizer V to the L lines and during return working feed to H. During the quick feed motions B and C are connected to H. Chamber A is screened against leakage by a groove A1. The valve Q controlling the quick-motions is actuated either from a cam Ql on the turret or by low hydraulic pressure in chamber Q3. The direction of motion is controlled by a reversing valve R and pilot H1 gives impulses to the various units. The impulse and operation selector consists of exchangeable cams G1 ... K1 on a cam shaft U operated in 30 degree steps by the turret slide movement. The cam shaft U also carries stops U3 for setting the main throttle T and stops U4 for setting the time-delay throttle D. The cross-slide n is actuated by a motor with three chambers a, b, c, controlled by a high speed valve q, stabilizer v and impulse transmitter f, g controlling the impulse conduits and operated by the feed stabilizer in its extreme positions. Singleacting motors h and d control the chuck and work reversal respectively. The functioning of the circuit in performing the same sequence of operations as that mentioned above is described in detail in the Specification.