Control of batching and curing processes

• US 5,749,986 A
• Filed: 08/01/1995
• Issued: 05/12/1998
• Est. Priority Date: 02/01/1994
• Status: Expired due to Term

• Current Assignee: Tison Technologies, LLC
• Original Assignee: Tracy A. Wyatt
• Inventors: Wyatt, W. Tison
• Primary Examiner(s): Simmons, David A.
• Assistant Examiner(s): Rivard, Paul M.
• Application Number:
  US08/509,975
• Time in Patent Office: 1,015 Days
• Field of Search: 324/433, 324/439, 324/444, 324/450, 324/713, 324/715, 324/717, 324/72, 324/72.5, 324/693, 156/64, 156/272.2, 156/272.4, 156/274.4, 156/274.8, 156/275.7, 156/352, 156/359, 219/765, 219/773, 219/778, 219/779, 364/476, 364/477
• US Class Current: 156/64
• CPC Class Codes: B32B 2309/02 Temperature
• CPC Class Codes: B32B 2309/72 For measuring or regulating, e.g. systems with feedback loops
• CPC Class Codes: B32B 2361/00 Phenoplast, aminoplast
• CPC Class Codes: B32B 37/00 Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
• CPC Class Codes: B32B 37/26 with at least one layer which influences the bonding during the lamination process, e.g. release layers or pressure equalising layers
• CPC Class Codes: G05D 11/138 by sensing the concentration of the mixture, e.g. measuring pH value

Abstract

Methods and apparatus for detecting and utilizing a voltage produced by a variety of materials for process control and analysis purposes.

Claims

1. A method for controlling a batching process wherein a first substance is placed in a mixing container and a second substance is added for combining with the first substance to produce a combined substance, said method comprising:

employing a pair of electrodes placed in contact with the combined substance, the electrodes being not electrochemically dissimilar;

monitoring voltage between the electrodes produced by the combined substance while the second substance is being added, without applying any external voltage; and

recognizing that a sufficient quantity of the second substance has been added when the monitored voltage crosses a predetermined threshold voltage.

2. A method in accordance with claim 1, which comprises terminating the addition of the second substance when the monitored voltage crosses the predetermined threshold voltage.

3. A method in accordance with claim 1, which comprises employing a pair of electrodes made of the same material.

4. A method in accordance with claim 1, wherein one of the electrodes comprises a container wall.

5. A method in accordance with claim 1, which comprises periodically withdrawing a quantity of the combined substance into a monitoring vessel, and employing the pair of electrodes to monitor voltage produced by the combined substance within the monitoring vessel.

6. A method for controlling a batching process wherein a first substance is placed in a mixing container and a second substance is added for combining with the first substance to produce a combined substance, said method comprising:

employing a pair of electrodes placed in contact with the combined substance, the electrodes being not electrochemically dissimilar;

monitoring voltage between the electrodes produced by the combined substance as a function of time while the second substance is being added, without applying any external voltage; and

evaluating the monitored voltage as a function of time to determine the proportional amount of the second substance added to the first substance.

7. A method in accordance with claim 6, wherein the step of evaluating the monitored voltage comprises comparing the monitored voltage as a function of time to a plurality of predetermined functions to determine the best match.

8. A method in accordance with claim 6, which comprises employing a pair of electrodes made of the same material.

9. A method in accordance with claim 6, wherein one of the electrodes comprises a container wall.

10. A method in accordance with claim 6, which comprises periodically withdrawing a quantity of the combined substance into a monitoring vessel, and employing the pair of electrodes to monitor voltage produced by the combined substance within the monitoring vessel.

11. A method for evaluating conformity of a substance to a predetermined standard, said method comprising:

placing a pair of electrodes in contact with the substance, the electrodes being not electrochemically dissimilar;

monitoring voltage between the electrodes produced by the substance as a function of time, without applying any external voltage; and

comparing the monitored voltage as a function of time to at least one predetermined function to determine a degree of conformity.

12. A method in accordance with claim 11, which comprises the preliminary step of determining the predetermined function by placing a pair of electrodes in contact with a control sample of the substance and monitoring voltage between the electrodes produced by the control substance as a function of time.

13. A method in accordance with claim 11, which comprises employing a pair of electrodes made of the same material.

14. A method for analyzing a substance, said method comprising:

placing a pair of electrodes in contact with the substance, the electrodes being not electrochemically dissimilar;

monitoring voltage between the electrodes produced by the substance as a function of time, without applying any external voltage; and

comparing the monitored voltage as a function of time to a set of predetermined functions to determine a best match.

15. A method in accordance with claim 14, which comprises employing a pair of electrodes made of the same material.

16. A method for monitoring change in a substance which changes in at least one characteristic over time, said method comprising:

placing a pair of electrodes in contact with the substance, the electrodes being not electrochemically dissimilar;

monitoring voltage between the electrodes produced by the substance as a function of time, without applying any external voltage; and

employing the monitored voltage to control a process.

17. A method in accordance with claim 16, which further comprises recognizing that a sufficient change has occurred when the monitored voltage crosses a predetermined threshold.

18. A method in accordance with claim 16, which further comprises comparing the monitored voltage as a function of time to a plurality of predetermined functions to determine the best match.

19. A method in accordance with claim 16, which comprises employing a pair of electrodes made of the same material.

20. A method for controlling a plastic laminate curing press having a pair of press plates between which a stack of phenolic resin-impregnated sheets is heated, said method comprising:

employing a pair of metallic elements on either side of the stack as electrodes, the electrodes being not electrochemically dissimilar;

monitoring voltage between the electrodes produced by the phenolic resin-impregnated sheets while the stack is being heated, without applying any external voltage; and

terminating heating of the stack when the monitored voltage decreases below a predetermined threshold voltage.

21. A method in accordance with claim 20, wherein said step of terminating heating comprises terminating heating of the stack when the monitored voltage decreases below the predetermined threshold voltage after a predetermined delay interval has elapsed.

22. A method in accordance with claim 20, wherein the step of employing a pair of metallic elements as electrodes comprises assembling a pile including alternating stacks of resin-impregnated sheets and metal separator sheets, and employing two of the separate sheets as electrodes.

23. A controller for controlling a plastic laminate curing press having a pair of press plates between which a stack of phenolic resin-impregnated sheets is heated, said controller including:

a heat control element for controlling heating of the stack;

a sensing circuit connected to electrodes on either side of the stack for monitoring voltage between the electrodes produced by the phenolic resin-impregnated sheets, without applying any external voltage, the electrodes being not electrochemically dissimilar; and

a control device connected to said heat control element and to said sensing circuit and operable to initiate heating of the stack and to subsequently terminate heating of the stack when the voltage between the press plates decreases below a predetermined threshold voltage.

24. A controller in accordance with claim 23, wherein said control device is operable to subsequently terminate heating of the stack when the voltage between the press plates decreases below the predetermined threshold voltage after a predetermined delay interval has elapsed.

25. A method for recognizing a change in state of a material, said method comprising:

placing a pair of electrodes in contact with the material, the electrodes being not electrochemically dissimilar;

monitoring voltage between the electrodes produced by the material while the change in state is expected to occur, without applying any external voltage; and

recognizing the change in state when the monitored voltage crosses a predetermined threshold voltage.

26. A method in accordance with claim 25, which comprises recognizing the change in state when the monitored voltage decreases below a predetermined threshold voltage.

27. A method in accordance with claim 25, wherein the material is a phenolic resin and the change in state is curing from liquid to solid form.

28. A method in accordance with claim 26, wherein the material is a resin, and the change in state is curing from liquid to solid form.

29. A method in accordance with claim 26, wherein the material is an epoxy resin, and the change in state is curing from liquid to solid form.

30. A method for recognizing a change in state of a material, said method comprising:

placing a pair of electrodes in contact with the material, the electrodes being not electrochemically dissimilar;

measuring voltage between the electrodes produced by the material while the change in state is expected to occur to develop a voltage signal, without applying any external voltage;

determining the rate of change of the voltage signal; and

recognizing the change in state when the rate of change reaches zero.