Method and apparatus for controlling the cure of a rubber article

Claim 3

A method according to claim 1 wherein the step of measuring a function of the temperature of the rubber is accomplished by inserting a temperature sensitive probe in the rubber.

Claim 4

A method according to claim 2 wherein the temperature sensitive probe is a thermistor.

Claim 5

A method according to claim 2 wherein the rubber is being cured in a closable mold and the temperature sensitive probe is inserted in the rubber after the closing of the mold.

Claim 6

A method according to claim 1 wherein the induction reaction period is calculated by taking the integral of the Arrhenius expression e (1/T 1/T) where Alpha i is the induction activation energy divided by the universal gas constant, To is a preselected test temperature and T is the measured temperature of the rubber.

Claim 7

A method according to claim 1 wherein the step of calculating the percentage of cross-link concentration includes taking the integral of the Arrhenius expression e (1/T 1/T) where Alpha x is the cross-link activation energy divided by the universal gas constant, To is a preselected test temperature, and T is the measured temperature of the rubber, the integral being divided by Tau xo, the cross-linking time constant.

Claim 8

A method according to claim 6 wherein the step of calculating the cross-link concentration includes solving the equation a 1 - e x where x equals the integral as divided by Tau xo to Determine the percent cross-link concentration.

Claim 9

A method according to claim 1 wherein the steps of calculating the induction reaction period and calculating the percentage of cross-link concentration include taking the integral of the Arrhenius expression e (1/T 1/T) where To is a preselected test temperature, T is the measured temperature of the rubber and Alpha is the activation energy divided by the universal gas constant, different activation energies being selected to calculate the induction reaction period and percentage of cross-link concentration.

Claim 10

Apparatus for controlling the cure of a rubber article according to the cross-link concentration thereof, said cure including an induction reaction period wherein essentially no change in the mechanical properties of the rubber occurs and a cross-linking reaction period wherein cross-linking of the rubber occurs comprising, temperature sensitive probe means insertable into the rubber article to provide an output signal proportional to a known function of the temperature of the rubber, circuit means receiving said output signal of said probe means and developing a signal proportional to the rate of cure of the induction period of the rubber article, means to integrate said signal proportional to the rate of cure of the induction period and providing an output signal proportional to the induction time period, first comparator means receiving said output signal of said means to integrate and an input signal proportional to a preselected value of induction time and providing an output signal upon a match thereof, said output signal of said first comparator means enabling said circuit means to develop a signal proportional to the rate of cure of the cross-linking period of the rubber article to be integrated by said means to integrate, means receiving said signal proportional to the integrated rate of cure of the cross-linking period and converting the same to a percent cross-link concentration signal, and second comparator means receiving said percent cross-link concentration signal and an input signal proportional to a preselected value of percent cross-link concentration and providing an output signal upon a match thereof to terminate the cure.

Claim 11

Apparatus for controlling the cure of a rubber article according to the cross-link concentration thereof, said cure including an induction reaction period wherein essentially no change in the mechanical properties of the rubber occurs and a cross-linking reaction period wherein cross-linking of the rubber occurs comprising, temperature sensitive probe means insertable into the rubber article to provide an output signal proportional to a known function of the temperature of the rubber, circuit means receiving said output signal of said probe means and developing a signal proportional to the rate of cure of the induction period of the rubber article, means to integrate said signal proportional to the rate of cure of the induction period and providing an output signal proportional to the induction time period, first comparator means receiving said output signal of said means to integrate and an input signal proportional to a preselected value of induction time and providing an output signal upon a match thereof, said output signal of said first comparator means enabling said circuit means to develop a signal proportional to the rate of cure of the cross-linking period of the rubber article to be integrated by said means to integrate, means receiving said signal proportional to the integrated rate of cure of the cross-linking period and converting the same to a percent cross-link concentration signal, and second comparator means receiving said percent cross-link concentration signal and an input signal proportional to a preselected value of percent cross-link concentration and providing an output signal upon a match thereof to terminate the cure.

Claim 12

Apparatus according to claim 9 wherein said probe means is a thermistor.

Claim 13

Apparatus according to claim 9 wherein the output signal of said probe means is an analog signal and including means to convert said analog signal to a digital signal.

Claim 14

Apparatus according to claim 11 wherein said means to integrate includes a digital adder, a buffer register, a clock pulse generator, and a counter.

Claim 15

Apparatus according to claim 9 wherein said circuit means also receives a signal proportional to a predetermined value for induction activation energy so that said signal proportional to the rate of cure of the induction period of the rubber article can be developed by said circuit means.

Claim 16

Apparatus according to claim 13 wherein said output signal of said first comparator means prohibits said circuit means from receiving said signal proportional to a predetermined value for induction activation energy and permits said circuit means to receive a signal proportional to a predetermined value for cross-linking activation energy so that said signal proportional to the rate of cure of the cross-linking period can be developed by said circuit means.

Claim 17

Apparatus according to claim 9, said output signal of said first comparator means enabling said circuit means to develop a signal proportional to the rate of cure of the cross-linking period by enabling a signal proportional to a predetermined value for cross-linking activation energy to be received by said circuit means.

Claim 18

Apparatus according to claim 15, said output signal of said first comparator means also enabling the output signal of said means to integrate to be divided by a predetermined cross-linking time constant.

Claim 19

Apparatus according to claim 16 wherein said means to integrate includes a counter and said output signal of said first comparator resets said counter.