Direct digital control of rubber molding presses

A method of operating a plurality of rubber-molding presses simultaneously curing precision molded compounds in conjunction with a computer, comprising:

• providing said computer with a data base for each said press including at least,
• natural logarithm conversion data (1n),
• the activation energy constant (C) unique to each batch of said compound being molded, and
• a constant (x) dependent upon the geometry of the particular mold of the said press,
• constantly informing the computer of the temperature (Z) of each mold,
• informing the computer of the batch of the compound being molded in each mold,
• constantly informing the computer of the elapsed time that the compound has been in each mold,
• repetitively performing for each said press at frequent periodic intervals during each curve in the computer, integrations to calculate from the series of temperature determinations the Arrhenius equation to determine the total required cure time, which is 1n v=CZ+x, where v is the total required cure time,
• repetitively comparing at frequent periodic intervals in the computer the calculated total required cure time and the elapsed time for each said press, and
• opening each said press automatically when its elapsed time has reached its calculated total required cure time.

A method of manufacturing precision molded articles from selected synthetic rubber compounds with the aid of a digital computer, comprising:

• providing said computer with a data base for a molding press to be used in the molding, including at least,
• natural logarithm conversion data (1n),
• the activation energy constant (C) unique to each batch of said compound being molded, and
• a constant (X) dependent upon the geometry of the particular mold of the press,
• installing prepared unmolded synthetic rubber of one said compound in a molding press cavity,
• closing said press,
• initiating an interval timer associated with said computer upon the closure of the press for monitoring the elapsed time of said closure,
• constantly determining the temperature (Z) of the mold at a location closely adjacent to the mold cavity in the press during molding,
• constantly providing the computer with the temperature (Z),
• repetitively performing in the computer, at frequent intervals during each cure, integrations to calculate from the series of temperature determinations the Arrhenius equation for reaction time during the cure, which is
• 1n v=CZ+x
• where v is the total required cure time,
• repetitively comparing in the computer at frequent intervals during the cure each said calculation of the total required cure time calculated with the Arrhenius equation and said elapsed time,
• opening the press automatically when a said comparison indicates completion of curing, and
• removing the resulting precision molded article from the press.

A method of manufacturing precision molded articles from selected synthetic rubber compounds in an openable rubber molding press having at least one heated precision mold, comprising:

• (a) heating said mold to a temperature range approximating a predetermined rubber curing temperature,
• (b) installing prepared unmolded synthetic rubber of a known compound in a molding cavity of a predetermined geometry as defined by said mold,
• (c) closing said press to mold said rubber to occupy said cavity in conformance with the contour of said mold and to cure said rubber by transfer of heat thereto from said mold,
• (d) initiating an interval timer upon the closure of said press for monitoring the elapsed time of said closure,
• (e) heating said mold during said closure to maintain the temperature thereof within said range approximating said rubber curing temperature,
• (f) constantly determining the temperature (Z) of said mold at a location closely adjacent said cavity thereof throughout closure of said press,
• (g) repetitively performing at frequent periodic intervals throughout closure of said press integrations to calculate from the series of temperature determinations the Arrhenius equation for reaction time of said rubber to determine total required cure time v as follows:
• 1n v=cz+x
• wherein c is an activation energy constant determined for said rubber being molded and cured in said press, and x is a constant which is a function of said predetermined geometry of said mold,
• (h) for each repetition of calculation of said Arrhenius equation herein, comparing the resultant calculated total required cure time with the monitored elapsed time measured by said interval timer,
• (i) opening said press when a said comparison of calculated total required cure time and monitored elapsed time indicates completion of curing, and
• (j) removing from said mold the resultant precision molded and cured rubber article.