Patent GB-548433-A (GB)
Title: Improvements in lathes and like machine tools
IPC: B23B5/00
Filed: 1941-07-07
Abstract: 548,433. Lathes &c. CLEVELAND TRUST CO. July 7, 1941, No. 8575. Convention date, July 25, 1940. [Class 83 (iii)] In a lathe or like machine tool, particularly for shell-turning of the kind having a tool-holding bar which is oscillated to feed the tool to the work and moved longitudinally for traverse, the oscillating movement is produced by a control bar which has an oscillating movement only. The frame comprises pillars 11, 12 and central bridge portion 13 which forms a chip-receiving pan which directs chips to the rear of the machine. The spindle 14 is driven from a motor 17 through belt gearing 19, clutch 46, and spur gearing 40,35. When the clutch is disengaged by a hand lever 50 the spindle is brought quickly to rest by a friction member 47 engaging a stationary brake 48. The spindle is fitted with an expanding arbor 20 for gripping the interior of the work, the arbor being actuated by a fluid pressure cylinder 21. The outer end of the work may be supported in a tailstock 15. A tool-holder 25, parrying a number of turning tools 26 is secured to. a bar 27 having both oscillatory movement, to cross feed the tools, and longitudinal movement for traversing. Another bar 28 parallel to bar 27 has ocillatory movement only; such movement being in unison with the longitudinal movement of bar 27 and being effective through a cam member 29 to impart oscillating movement to bar 27. Both bars are operated by a cam shaft 30 driven from the work-spindle for feed movements or independently at high speed from a motor 31 for idle movements. For the feed drive a belt 52 connects the spindle to a shaft 54 connected through change gears 59 and worm gearing 63 to a planet carrier sleeve 65, Fig. 7, rotatable on the hub 66 of the wheel 67 of a differential gear. The sun wheel 72 of this mechanism is keyed on a shaft 68 connected to the cam shaft by worm gearing 92. The hub 66 may be braked by shoes 74 actuated by energizing a solenoid 78. The shaft 68 is also connected by a belt 84 to a motor 31. If the motor 31 is stationary and the brake disengaged, the hub 66 revolves idly and no movement is imparted to wheel 72 and shaft 68, but if the brake is applied the hub 66 is arrested and the feed shaft 68 is driven at feed speed. If the brake is released and the motor 31 energized the spindle 68 is driven directly from the motor and the sleeve 66 is idly rotated. The shaft 68 may also be rotated by a crank 87 arranged to operate a switch 90 so that neither the motor 31 nor the solenoid 78 can be energized when the hand crank is in position. The cam drum 93 has a track 94 engaged by a roller 95 to impart longitudinal movement to the bar 27 which is also free to rock in the sleeve carrying the cam follower. The drum also carries a cam 102 which rocks a bar 108 to which may be secured a holder 125 for end-facing tools 126. This bar may be omitted. The right-hand end, Fig. 1, of the cam shaft carries a cam 109 connected through lever-arms and link 115 to a member 116 on the bar 28 to impart oscillating movement thereto. Switch operating fingers 117 on the cam shaft operate a series of switches 120-122 in the control system in predetermined sequence. The tool holder 25 is provided with a hardened shoe 123 coacting with a cam 29 on the bar 28. In the position shown in Fig. 4 the cam 29 acts to hold the tool up to the work but if the bar 28 is rotated clockwise the cam 29 allows the tools to fall away from the work so that the bar 27 may be returned longitudinally without damage to the work. A taper 124 on the end of cam 29 assists in bringing the tools gradually up to the work. When the bar 108 is employed, its tool holder 125 is fitted with end facing tools 126 which, when the bar is rocked, face up the two ends of the work. In a modification, the tailstock is removed and the work is gripped externally in a spring-jawed chuck 127. A tool-holder 28 clamped to bar 27 carries a boring-bar 129 fitted with a boring tool 130. The boring-bar is moved longitudinally for its idle travel by a fluid pressure cylinder 132, the working feed being obtained by the above described longitudinal movement of the bar 27. The bar 28 has a cam 133 which in one position, Fig. 14, maintains the boring bar in alignment with the work. After retraction of the boring bar the bar 28 may be rotated so that the cam 135 allows the boring-bar to move aside from the work which may then be removed. When the tool holder 128 is rocked to inoperative position a tray 136 secured to the tool holder may be arranged to come into a position below the work and in line with a trough 137 fixed to the pillar 12 to facilitate unloading and loading the work on to or from a conveyer at the right-hand end of the machine. The tool-holder 25 may similarly be provided with means for loading and unloading the work. For this purpose the tool holder may be formed with a trough from which the work may be pushed on to conveyer bars 140. In a further modification, Fig. 16, a tool-holder 141 may carry a socket 143 for a drill and a socket 145 for a tap, these tools being selectively brought into alignment with the work axis by the engagement of an elongated cam 146 on the bar 28 with one or other of the abutments 147, 148 on the tool-holder. The oscillations of the member 141 are effected while the tools are clear of the work. When the cam 146 is moved to an inoperative position the tool-holder is swung in a clockwise direction by a counterweight 141a to permit unloading of the work. Lubrication is effected by a pump 151 driven from a motor 152. The delivery pipe 155 leads to a channel 156 whence conduits 157 extend to the machine bearings. From these bearings the oil passes to a pump in the base of the machine for recirculation. If the oil pressure fails, a switch 158 is automatically opened to stop the machine. The control circuit, Fig. 17, includes relays 165, 166 for the motors 17 and 31 associated with the brake solenoid 78, the relays being operated by solenoids 188, 199. In operation the pump motor 152 is first started by the switch 162. A starting switch 169 is then closed to energize solenoid 182 of the starting switch of motor 17. This closes holding switch 184. A switch 171 is provided for " jogging " the motor 17. The work is now chucked and the spindle clutch engaged. For slow feed the lever 178 is moved to cause a cam 175 to close switch 172, energizing solenoids 188 and 78 to apply the brake 74 and give the feed drive of the cam shaft. For fast approach speed the cam 175 is moved fully to the left thus closing switch 173 and energizing solenoid 199. This de-energizes the solenoid 78 to remove the brake and starts motor 31 through its forward switch 204, the cam shaft then being driven at high speed to give the approach movements of the turning and facing tools. When the tools reach the cutting position one of the fingers 117 actuates its switch 121 to de-energize solenoid 199 and stop motor 31. The brake 74 is also applied and feed of the tools is effected. At the end of the feed movements a finger 117 actuates switch 120 to disengage the brake and restart the motor 31 to give the high cam-shaft speed, the tools being withdrawn from the work before the return movement of bar 27. Finally another finger 117 actuates switch 122 to stop motor 31 and de-energize the brake so that the cam shaft stops. The main clutch 50 is then disengaged and the work unloaded. The motor 31 may be run in reverse direction under control of a jog switch 175a for setting-up purposes.