GB1482164A - Apparatus for manufacturing film-type resistors - Google Patents

Abstract

1482164 Manufacturing resistors R E CADDOCK 13 Dec 1974 [14 Dec 1973] 54033/74 Heading H1S [Also in Division B6] Apparatus for screen printing on the surface of a ceramic cylinder 10 to form an electrical resistor comprises rollers 91 to support the cylinder at its ends and beneath a silk screen 30a, and a squeegee 71 and flood bar 77 supported adjacent each other above the screen by a lever system comprising a first pair of arms 61 which are pivoted on fixed brackets 43 and carry the squeegee and a second pair of arms 75 which carry the flood bar and are pivoted on the first pair, a pair of stops 58 acting on the arms 75 to raise the flood bar when the squeegee is lowered on to the screen, and means to raise and lower the arms 61 carrying the squeegee. As described the arms 61 can be raised by the piston 103 of an air cylinder 56 in a pneumatic circuit containing valves which are controlled by limit switches 83, 86. These switches are actuated as a frame 51 carrying the screen is moved to and fro in tracks 53. The support rollers 91 are borne by a carriage 54 which can be reciprocated within guides 89, a different carriage being used for each size of cylinder 10. The carriage is loaded in its outer position and then pushed in to the position shown in Fig. 8, the squeegee being slightly raised by the piston 103, which allows the arms 75 to drop on to the stops 58 so that the flood bar is adjacent the screen. The screen frame is then pulled out, spreading ink over the top surface of the screen, and actuating switch 83 to lower piston 103. This allows the squeegee to drop to a position determined by a screw 57 and in contact with the screen which is thereby pressed into engagement with the cylinder 10, the flood bar being simultaneously raised by the stops 58. The screen frame is then pushed in, printing the cylinder 10 which rotates on the rollers 91, and actuating switch 86 to raise the squeegee. The carriage 54 can then be withdrawn for a new cylinder to be placed in position. The printed material may be resistive or may be an acid-resistant material printed on a resistive coating prior to etching, the resultant resistor being generally as in Specification 1,409,127.