Process for imprinting spaced-apart web sections with a composite pattern

Abstract

A machine for printing a recurrent pattern on sections of predetermined length of a textile web, comprising a number of parallel rotary-screen printing units spaced apart in the direction of web motion, includes a first sensor for detecting the leading edge of an oncoming web section to be imprinted and a second sensor for ascertaining the passage of a mark indicating the start of a printing pattern on the first unit. The odd-numbered units print the first half of the pattern, in different colors, whereas the even-numbered units print the second half in corresponding colors; between printing operations, the screen of each unit is lifted off the web and can be angularly readjusted to compensate for relative disalignment between the web sections and the printing patterns. Such disalignment is determined by the two sensors whose output signals are translated into command signals sequentially delivered to control inputs of the several odd-numbered units at equal intervals for making the necessary adjustments just before the arrival of the leading edge of a web section at these units; the control inputs of the even-numbered units receive these commands at instants delayed with reference to the midpoints of these intervals so that their adjustments take place after that leading edge has passed them. Where the sections to be imprinted are tufted fabric piles, the first sensor comprises two juxtaposed feelers, one loaded by a hard spring and the other loaded by a soft spring; an oncoming pile edge elevates the latter but not the former to cause completion of a signal circuit discriminating against seams in the web which would cause both feelers to be elevated concurrently.