In the manufacture of glass articles and particularly in the manufacture of glass containers or glass bottles using the blow-blow process or the press-blow process in an I. S. machine, generally one with double or triple cavity or sections, it is common for the containers, at certain time intervals, to stick to the molds. This happens with parison molds or with blow molds.
The sticking of the containers to the molds, is due principally to the fact that the mold temperature goes above a determined temperature limit. This increase in the temperature of the molds, generally takes place when the molds become dry for lack of lubricant.
This problem is easily solved by cleaning the glass of the containers that stuck to the molds and lubricating the mold cavities. However, said lubrication has as a consequence that the first containers formed in the recently lubricated molds come out thinner with a thicker bottom and with a superficial coating of lubricant which is hard to remove. This is why they have to be removed from the production line before they are given a thermic treatment (annealing or tempering) and packaging.
The rejection of the containers spotted with lubricant, which travel on the machine's conveyor, is usually carried out in a semi-automatic manner through the "rejector" which is made up of a hydraulic or pneumatic device which moves a piston or rod which knocks out the containers when the operator makes it work in syncronism with the speed of the conveyor so that the rejected containers can be eliminated from the same.
However, the said semi-automatic devices have a problem in that they are not able to identify the containers formed in a cycle or in a given section, nor are they able to determine the number of articles that must be scrapped. For this reason they do reject an indiscriminate amount of them with the corresponding losses and production reduction.
The apparatus claimed by Gardner's U.S. Pat. No. 4,332,606 tries to solve the previous problem through the introduction of a manual circuit breaker for each mold of each section of the machine and a pulse generator which corresponds to the articles manufactured by the machine. Thus, when the operator lubricates certain molds and actuates the corresponding circuit breakers, the apparatus is enabled, by the pulse generator to identify the articles of said molds, which are transported on the conveyor to reject those articles exclusively. Said apparatus can also include a photo sensor located next to the rejecting device and so correct the slight delays in the position of the articles selected.
In the U.S. Pat. No. 4,152,134 is claimed an electronic control system that actuates a rejection device similar to the previous one, activated by the operator through a control panel with which the molds and the section which needs to reject the articles can be selected.
Nevertheless, even when the apparatus of the previous art are already able to identify articles that need to be rejected, the loss problems and the consequent production reduction have not yet been solved since they are not able to identify when it is necessary to lubricate the molds. Consequently the articles stick to the molds and a number of articles are thus wasted.
Besides, after cleaning and lubricating the molds, since the said apparatus do not include a programmer to set the number of containers that must be rejected because they are spotted with lubricant, generally the articles keep being rejected indiscriminately until the operator becomes aware that good articles are being rejected thus increasing the losses and reducing production.
Because of the above, the inventors of the present invention, taking into account all of the problems presented by the previous art, invented an automatic article rejector which is able to identify and send a prompt notice when it is necessary to lubricate the molds of a given section, and this is done before the articles stick to the molds. The rejector is capable of identifying and rejecting precisely the articles that correspond to the lubricated molds and the section within the same, thus rejecting only a predetermined number of articles, and it automatically suspends the rejection signal of the rejection device, thus lessening the number of lost articles and permitting a production increment.