Dyeing machine with automatic in-line dip depletion control

Dyeing machine comprising:

• a container (11) in which products to be dyed are placed;
• a source (12) of coloring liquids adding liquids on command into the container to realize a dye dip;
• a unit (13) to circulate the dye dip with respect to the product;
• spectroscopic analysis means to perform a spectroscopic analysis on the liquids and an electronic control and calculation device (15) receiving the spectroscopic analysis data and calculating therefrom the concentrations of the various dyes in the dip on the basis of previously memorized spectroscopic information for the individual dyes;
• characterized in that the spectroscopic analysis means comprise a sampling and analysis device (14), which during the dyeing process automatically takes liquid samples in the container to a reading cell (18), at intervals, and performs a spectroscopic analysis on the taken samples in the reading cell (18);
• and
• characterized in that the sampling and analysis device (14) comprises a reading cell (18) having a passage (26) for the liquid with controlled variable gauge (d) and through said gauge (d) is made to pass a measuring light detected, after the passage, by a spectrophotometer (20) sending the data to said electronic device (15) which performs the spectroscopic analysis for calculation of the concentrations.