Patent GB-559629-A (GB)
Title: Improvements in metal spray guns of the wire feed type
IPC: B05B7/20
Filed: 1942-09-04
Abstract: 559,629. Metal-spraying apparatus. METALLIZING ENGINEERING CO., Inc. Sept. 4, 1942, No. 12519. Convention date, Dec. 1, 1941. [Class 69 (iii)] [Also in Group XXVI] A metal spray gun construction of the wire feed type, having a compressed air or other gas motor is provided with variable speed governing mechanism comprising a speed-measuring device embodying one or more centrifugally deflectable arms, a speed-controlling structure actuated by the speedmeasuring device and means for variably adjusting the sensitivity of the governing mechanism between minimum and maximum operating speeds. In the gun shown in Fig. 9, a mixture of oxygen and acetylene passing through passages 36 melts the wire 37. Air passing around the burner tip 34 subdivides, and propels, the molten metal from the burner. The wire is fed by spring- pressed wheels 52, 53 driven by an air turbine controlled by a centrifugal governor. In the embodiment shown in Fig. 5, the governor is of the power-absorption type and comprises bent blade springs 200 secured to the turbine rotor 95 and carrying at their free ends weight buttons 202 and weighting nuts 203. Slidable on the turbine shaft 80, and in driving engagement with the buttons 202 is an assembly consisting of a hub 205, brake disc 206 and bent clip 207. During the rotation of the turbine the brake disc is frictionally engaged by an annular face on a spider 215 which may be manually adjusted towards or away from the brake disc by rotating a knurled ring 216 so as to apply a braking effect corresponding to any desired speed. The braking surface of the spider 215 is preferably made of sprayed bronze. When the power required to feed the wire 37 varies, for example, due to irregularities in the wire, the braking effect (governed by the straightening of the blade springs 200) is correspondingly varied to maintain a constant feed. In a modified braking device, Fig. 14 (not shown), the weight button 202 bears directly on the adjustable spider 215. In a further modification, Fig. 15 (not shown), the adjustable spider 215 is replaced by a brake disc carried at the end of a manuallyadjusted screw. In a further embodiment, the governor is of the type that maintains the speed of the turbine substantially constant by throttling its supply of compressed driving air. The driving air, from a duct 19, Fig. 18, passes between a valve seat 310 and a valve plunger 304. If the load on the turbine varies, the slight change in speed of the rotor displaces the assembly 601 as described in connection with Fig. 5, and causes displacement of the valve plunger 304 to vary its throttling effect and maintain a substantially uniform speed to the turbine. The valve seat 310 may be screwed in or out by means of a thumb wheel 309 in order to adjust the working speed of the turbine. In a further modification, Fig. 19 (not shown), the spring governor frictionally engages a resiliently-held disc having sufficient loose motion to intercept variably a portion of the rotor-driving jet and thus maintain the speed substantially constant. Specifications 559,628 and 559,630 are referred to.