Patent GB-835361-A (GB)
Title: Improvements in or relating to a method of and apparatus for manufacturing projection lamps
Inventor: TODD HAROLD EDGAR
IPC: B24B13/015
Filed: 1958-03-06
Abstract: 835,361. Setting projection lamps. GENERAL MOTORS CORPORATION. March 6, 1958, No. 7225/58. Classes 39(2) and 75(4) [Also in Group XXIII] A projection lamp, such as a sealed beam lamp for a vehicle headlight, is provided with a surface for setting against a corresponding surface of its housing so that its beam is directed at the desired angular inclination; this is effected by temporarily mounting the lamp in a support and aiming its beam appropriately to a fixed reference plane, and then with the lamp in this position forming, as on its rim, a surface having a predetermined angular relation to the reference plane. The operations may be carried out at successive stations on a turret machine 10, Fig. 1. At the first station the operator inserts a sealed beam lamp 64 in a frictional gimbal ring mounting 68, 72; at station 22 the beam from the lamp is aimed on a screen and scanned by photo electric cells which control servomotors 124, 140, Fig. 2, which act upon the frictional gimbal rings 68, 72 to adjust the beam in elevation and azimuth so that it has the required inclination to the reference plane of the screen 104; at station 24 a gauging is effected by the apparatus shown in Fig. 4 to determine the amount of feed that is required for a grinding of reference abutments 84 on the lamp rim and to check that these are present and all of uniform height; at station 26 the grinding is effected with the feed limited by a stop 380, Fig. 5, adjustably set by the gauging apparatus whereby the reference abutments are ground to give a reference surface such that the lamp when assembled in its housing will give a beam of the required angular direction. At the aiming station the lamp 64 mounted in the gimbals 68, 72 respectively frictionally pivoted at 70/70<SP>1</SP>, 74/74<SP>1</SP> and illuminated from a battery 92 has its beam focused by a condensing lens 100 on to a screen 104 having photo-electric cells symmetrically arranged therewith whereby a differential effect arises in each of two detectors 116, 132 if the beam image is not centralized for elevation and azimuth, the detectors then causing servomotors 124, 140 to act through clutched-in shafts 94, 96 to position the gimbal rings 68, 72 so that the beam has the correct angular setting relatively to the screen. These actions are under the control of a motordriven sequence timer 28, Fig. 1, which applies potential to contacts 30, 32, 34...48 at proper times in the turret operation whereby are operated the turret drive and the servomotors, clutches, and the relays for controlling the gauging, grinding feed, and rejection of lamps defective in beam positioning or with constructional defects. If a lamp cannot be positioned to set its beam correctly on the screen 104 then a detector 216 energized either from the elevation or the azimuth detector 116, 132 will energize a memory device 228 which will prevent the subsequent gauging operation being carried out on this lamp. In the setting of the beam the elevation and azimuth servomotors initially set the gimbal rings into their backward limit and the servomotors thereafter move the gimbal rings forward until the detectors 116, 132 give a null indication which occurs when the beam is correctly positioned relatively to the screen. When the lamp bulb reaches the gauging station, and providing it is not a defective one in which case the memory device 228 will have applied potential to the terminals 230 to interrupt the device 240 which will then prevent hydraulic actuator 236 being effective, the hydraulic actuator 236 will depress a reference head 232 against a fixed stop 246 while a plunger 250 pressing against the lamp rim will be moved relatively upward to modify the position of a contact point 260 on a resistance 258 and actuate a memory device 268 such as of the self-balancing potentiometer type. Subsidiary plungers 300 sliding in a gauging head 248 which bears on to the lamp rim verify the presence of the reference abutments 84 on the lamp rim; if any one abutment is absent or broken one or more of the multiple contacts 310 will remain closed and prevent a memory latch-up relay 324 being energized to affect an interruptor 396 for the control of the grinding feed mechanism 376. At the grinding station, the servomotor 396 is actuated to an extent determined by the extent to which the memory device 268 has been set and so sets, through a wedge adjustment 382 the position of a stop 380 to set the limit of the grinding feed. The grinding is effected by an inverted cup wheel 366 the driving shaft 372 of which is set at a known angle with respect to the aiming screen and therefore grinds the abutment surfaces 84 to give a known angle with the beam. Specification 804,739 is referred to.