Color variation control process for molding plastic and composite multi-color articles
View Patent ↗A process to effect random color variation in multi-color molded articles includes feeding individual colors to molding equipment in a pre-established sequence and manner that prevents substantial mixing of the colors, and at pre-established ratios in relation to a non-integer multiple of volume associated with the molded article.
1. A system for molding multi-colored articles comprising:
a) molding equipment;
b) a feeding system capable of individually feeding two or more colored materials to the molding equipment through a single screw feeder;
c) a process control module programmed to control the feeding system for repetitive delivery of the colored materials to line molding equipment wherein the process control module is programmed to:
i) specify:
i) a number of colors to be used in the molded article,
ii) approximate ratios of the colors in the molded article, and
iii) the sequence of the colors in the molded article;
ii) determine a modified total mold volume that is a non-integer multiple of an actual total mold volume associated with the article;
iii) operate the feeding system to feed the individual colors to the molding equipment in said sequence at said ratios in relation to the modified total mold volume until the volume of individual colors fed to the molding equipment reaches either the modified total mold volume if the modified total mold volume is less than the actual total mold volume, or the actual total mold volume if the modified total mold volume is greater than the actual total mold volume; and then
iv) one of:
i) repeat said feeding of the individual colors to the molding equipment to fill the actual mold volume if the modified total mold volume is less than the actual total mold volume or to fill a successive actual total mold volume if the modified total mold volume is greater than the actual total mold volume, or
ii) either (a) re-specify one of said number of colors, said approximate ratios or said sequence, or (b) redetermine said modified total mold volume with respect to the actual mold volume, and then repeat said feeding of the individual colors to the molding equipment.
2. A system as defined in claim 1 in which the molding equipment comprises high and low level input sensors providing signals to the process control module to assist in controlling said delivery of the colored materials to the molding equipment.
3. A system as defined in claim 1 in which the feeding system is further configured to deliver the colored materials to the molding equipment in a substantially unmixed condition.
4. The system as defined in claim 3 in which the feeding system includes a screw drive to deliver the colored materials to the molding equipment, the screw drive is a deep-cut, low-shear drive capable of moving material forward toward the molding equipment in a substantially unmixed condition.