Patent GB-1350583-A (GB)
Title: Mass-production plants
IPC: G07C3/14
Filed: 1970-08-07
Abstract: 1350583 Selective signalling ASSOCIATED ENG Ltd 6 Aug 1971 [7 Aug 1970] 38275/70 Heading G4H [Also in Divisions G1 and B6] In a mass-production plant for producing a component, comprising a plurality of machine tools each operable to produce the component, each component has applied to it a code marking identifying the machine tool which produced it, and a common test apparatus receives components produced by all the machine tools and produces an error signal when a parameter of a component tested falls outside a predetermined limit or limits, there being means operative by the error signal to inhibit the operation of the machine tool indicated by the code marking of that component after it has produced a predetermined number of faulty components (which may be one). In the particular embodiment, the components are pistons, but may alternatively be gudgeon pins, cylinder liners or piston rings. The machine tools may be numerically controlled by magnetic tape or punched cards. Application of code markings at a machine tool.-Passage of the piston actuates a microswitch to open a solenoid-operated valve so that ink or paint of a colour characteristic of the machine tool is sprayed on to the flat crown of the piston, or two sprays giving a combination of two colours could be used. Alternatively, a roller receiving non-reflective ink or paint from a reservoir or sponge has projecting flanges in a coded combination of positions contacting the crown of the piston to mark a coded combination of bars. Dots could be used instead of bars, and either could be provided by spraying through a mask. A roller could be used in the single-colour case. Concentric circles could be used as the marking, or axially-spaced circumferential lines around the piston skirt. A reciprocable pad could be used for applying the marking. Reflective paint could be used, or magnetic ink. Reading the code marking at the test apparatus.-Light is reflected from the code marking on to an array of photo-cells via respective filters in the colour-coded case. In the bar coding case, a line of solid-state radiation source and detector devices each illuminate and receive any light reflected from a respective position in which a bar may occur. In the bar and dot cases, a source and a plurality of photocells may be used. Other operations at the test apparatus.-After reading of the code marking (see above) the skirt diameter of each piston (i.e. component) is measured by means of proximity-sensitive inductive probes, or proximity-sensitive air pressure callipers with interferometric means for sensing the separation of the callipers, a digital readout being produced on a meter. High and low number recognition units detect if the readout value is too high or too low respectively to produce a pulse to operate a respective solenoiddriven flap to divert the piston from an outlet conveyer to a high or low reject channel respectively. The code marking is removed at a washing station downstream of the flaps. The output from the code-marking reader, decoded to 1-out-of-n form unless already in this form, is set into bi-stable circuits previously reset by detection (by microswitch or photo-cell) of entry of the piston into the code-marking reader. A pulse from the high or low number recognition unit is gated under control of the bi-stables to a high or low counter (respectively) respective to the set bi-stable. If either of such a pair of counters reaches a predetermined count, the respective machine tool is stopped. The counters may be omitted, the outputs of the high and low number recognition units being ORed together and gated by the bi-stables to stop the appropriate machine tool.