GB1388475A - Flaw detector - Google Patents

Abstract

1388475 Detecting flaws photo-electrically JOHN DALE Ltd 14 March 1973 [8 Feb 1972] 5922/72 Heading G1A Apparatus for detecting flaws in hollow articles comprises a source of electromagnetic radiation separated from sensing means by a shield movable to a retracted non-shielding position, and means for entering the hollow article over the source. As shown, Fig. 1, an I.R. source or incandescent lamp 18 is supported at the end of a fixed tube 16 mounted in a housing 10 the forward end of which has a head member 32 carrying twelve light sensitive switches 33 disposed round the source 18. A shielding tube 20 surrounds the source 18 and fixed tube 16 and is biased to the left by means of a tension spring 23. The forward end of the shielding tube 20 is provided with a member 30 having an annular recess 31 which receives the open end of the hollow article which may be a collapsible tube. The closed end of the article is engaged by a conical recess 57 in a nylon block 56 which is moved longitudinally by a double acting pneumatic ram 37. In operation a conveyer (not shown) presents an article to the apparatus the ram 37 is operated so that the open end of the article (the skirt of a collapsible tube) enters the recess 31 and pushes back the shielding tube 20. The article surrounds the light source 18 and any flaw in the tube is detected and a signal passed to a memory circuit for subsequent operation of an ejection mechanism. The ram is then returned to its starting position allowing the tube to be pushed out of the apparatus on to the conveyer by the spring loaded shielding tube. The ram 37 also actuates micro-switches 47 and 48 by means of sliding shaft 45. When the end of the shaft 45 releases the operating arm of switch 48 the memory circuit is interrogated and if a flaw was detected two lifting rams (35) are operated to pivot ram 37 so that block 56 is moved clear of the end of the article. A blast of compressed air is then applied via a plenum chamber 60 and the forward end of tube 20 to remove the article from the conveyer. Further movement of ram 37 actuates switch 47 to reset the memory circuit and return the ram to its operating position. If no fault is detected the article is moved on by the conveyer which presents the next article for test.