GB1158125A - Improvements In Scratch Testing Apparatus - Google Patents

Abstract

1,158,125. Scratch testing machine. FORMICA INTERNATIONAL Ltd. April 9, 1968 [Feb.18, 1967], No.36994/66. Heading G1S. The test piece 3 is retained in a holder 4 by a spring-loaded catch below a frame 7 and is mounted on a carriage 5 slidable in grooves 6. A stylus 8 such as a steel needle or a diamond is detachably mounted on an arm 10 pivotally mounted on a gimbal plate 12, and is adjustably and progressively loaded by movement by the carriage 5 of a sliding weight 15 along the arm 10, the scratch pattern being as in Fig. 1. and starting at Z, the distance of Z from a fixed datum being measured to gauge the scratch resistance. A drive motor 33 rotates a crank disc 27 to which is attached a telescopic shaft 26, 28 by means of a ball and socket joint 31. This linkage is attached to a stirrup 25 which as the shaft 26 rotates oscillates a shaft 21 mounting the gimbal and reciprocates the stylus across the test piece in an arcuate manner, the oscillation being guided by a ball bearing 17 fixed beneath the weight and rolling over an arcuate stop member 18 on and moving with the sliding carriage. The carriage is propelled by a sprocket 36 driving a screwed rod 34 journalled in fixed brackets 35 and connected to the carriage via driving half nuts 39 mounted on spring blades 38 depending from the carriage. To halt the carriage drive, a rod 43 is lifted to pivot fevers 41 and raise a bar 40 to push away the spring blades 38 and disengage the driving half nuts from the threaded shaft 34. The carriage is manually retracted and electrical limit switches may be used to arrest the driving means at the end of a test.