Closed loop interactive controller

• US 6,529,796 B1
• Filed: 07/21/1999
• Issued: 03/04/2003
• Est. Priority Date: 07/21/1999
• Status: Expired due to Term

• Current Assignee: Caco Pacific Corporation
• Original Assignee: Caco Pacific Corporation
• Inventors: Rubow, Keith A., Kroeger, Charles R., Anderson, Rolf T.
• Primary Examiner(s): Picard, Leo
• Assistant Examiner(s): RODRIGUEZ, PAUL L
• Application Number:
  US09/358,323
• Time in Patent Office: 1,322 Days
• Field of Search: 700/200-202, 700/299, 700/300, 425/143, 425/144, 264/40.1, 264/40.6
• US Class Current: 700/202
• CPC Class Codes: B29C 2049/7874 Preform or article shape, weight, defect or presence
• CPC Class Codes: B29C 2945/76003 Measured parameter
• CPC Class Codes: B29C 2945/76083 Position
• CPC Class Codes: B29C 2945/76254 Mould
• CPC Class Codes: B29C 2945/76381 Injection
• CPC Class Codes: B29C 2945/76498 Pressure
• CPC Class Codes: B29C 2945/76702 Closure or clamping device
• CPC Class Codes: B29C 45/1774 Display units or mountings therefor; Switch cabinets
• CPC Class Codes: B29C 45/2737 Heating or cooling means therefor B29C45/7331 takes precedence
• CPC Class Codes: B29C 45/768 Detecting defective moulding conditions B29C45/84 takes precedence
• CPC Class Codes: B29C 45/78 of temperature
• CPC Class Codes: B29C 49/42382 Stopping at least a part of the machine
• CPC Class Codes: B29C 49/42407 Procedures for start-up or material change
• CPC Class Codes: B29C 49/78 Measuring, controlling or regulating
• CPC Class Codes: G05B 11/42 for obtaining a characteristic which is both proportional and time-dependent, e.g. P. I., P. I. D.
• CPC Class Codes: G05B 19/0421 Multiprocessor system
• CPC Class Codes: G05B 2219/21007 A processor to evaluate signals of detector only, I-O processor
• CPC Class Codes: G05B 2219/2214 Multicontrollers, multimicrocomputers, multiprocessing
• CPC Class Codes: G05D 23/1917 using digital means
• CPC Class Codes: G05D 23/1934 each space being provided with one sensor acting on one or more control means

Abstract

An injection mold apparatus has multiple injection zones, each zone having at least one heater and at least one temperature sensor generating a temperature indicating signal. A power source provides power to the heaters. A controller controls the temperature of at least some of the zones. For efficiency, the controller has two separate processors, a data-receiving processor for receiving temperature indicating signal from each sensor as well as power signals, and a control processor for receiving data from the data-receiving processor and for controlling the amount of power provided to the heaters. Preferably, the control is in a housing, with the housing mounted directly on the mold. Modified PID calculations are utilized. Power calculations for the amount of power to the heaters utilizes a modulo based algorithm.

Claims

1. An apparatus comprising:

(a) multiple zones, each zone having at least one heater and at least one temperature sensor outputting a temperature indicating signal;

(b) a power source providing power to the heaters; and

(c) a controller for controlling the temperature of at least some of the zones, the controller comprising;

(i) a data-receiving processor for receiving the temperature indicating signal from each temperature sensor, computing RMS values corresponding to measured heater currents and computing the average of the temperature indicating signals;

(ii) a power driver comprising respective on/off switches for controlling power to each heater, respective current sensors for measuring the heater currents in each heater, and a zero crossing detector for triggering the on/off switch; and

(iii) a separate control processor for receiving data from the data-receiving processor, storing a selected range for the temperature in each zone, performing a PID calculation of the amount of power required to maintain the temperature of each zone within a selected range based on the values computed by the data-receiving processor, and for controlling the amount of power provided to the heaters in response to the data received from the data-receiving processor, the separate control processor comprising a zero crossing interrupter interposed between the zero crossing detector and the on/off switches to provide only complete AC cycles to the heaters;

whereby each zone is maintained within the selected range of operating temperatures.

2. The apparatus of claim 1, wherein each zone has at least one chiller, the apparatus further comprising a source providing a cooling medium to the chillers, the separate control processor also controlling the amount of chilling medium provided to the chillers in response to data from the data-receiving processor.

3. The apparatus as claimed in claim 1 or 2 wherein the controller comprises a closed loop feed back circuit.

4. The apparatus of claim 1 wherein the temperature indicating signals are analog and the controller comprises at least one analog to digital converter for converting the temperature indicating signals to digital signals.

5. The apparatus of claim 1 wherein the apparatus is a mold having multiple injection stations, and the controller is in a housing, the housing being mounted on the mold.

6. The apparatus of claim 2 wherein the apparatus is a mold having multiple injection stations, and the controller is in a housing, the housing being mounted on the mold.

7. The apparatus of claim 5 comprising an insulating air gap between the housing and the mold.

8. The apparatus of claim 1 or 2 comprising at least 48 zones, and wherein there are at least two data-receiving processors, each receiving temperature indicating signals.

9. The apparatus of claim 1 wherein the apparatus comprises an injection mold having multiple injection zones, and each injection zone is used to form molded components, and the apparatus comprises respective transformers for measuring the current to each heater, and an alarm responsive to an out of control condition comprising an abnormal heater current if present and, if present, a condition selected from the group consisting of incomplete ejection of a molded component from the mold, irregular spacing between mold components, and incorrect weight of molded components.

10. The apparatus of claim 9 further comprising a switch responsive to the alarm for automatically shutting down the apparatus in response to the out of control condition.

11. An apparatus comprising:

(a) multiple heated zones, each zone having a target temperature and

(i) a temperature sensor providing a temperature indicating signal; and

(ii) a heater;

(b) a power source providing AC current to each heater;

(c) a detector detecting the amount of current provided to each heater; and

(d) a controller comprising;

(i) a first processor for receiving the temperature indicating signals;

(ii) memory for storing the target temperature for each zone;

(iii) a separate second processor for comparing the actual temperature of each zone against its target temperature and for comparing the detected heater current with an alarm threshold; and

(iv) an output signaler for regulating the percentage of complete current cycles provided to the heater for each zone, the output signaler being responsive to the comparison of heater current with the alarm threshold for detecting an alarm condition when any of the heater currents exceeds the alarm threshold.

12. The apparatus of claim 11 wherein the apparatus is a hot runner injection mold.

13. The apparatus of claim 12 wherein the controller is mounted on the mold.

14. The apparatus of claim 11 wherein the second processor determines the number of current cycles required to achieve the target temperature and compares the determined number against the number of current cycles actually being provided to the heater.

15. The apparatus of claim 11 further comprising a switch responsive to the second processor for automatically shutting down the apparatus in response to the alarm condition.

16. The apparatus of claim 11 comprising an on-off switch for each heater, the switch being responsive to the output signaler.

17. The apparatus of claim 16 wherein there are a plurality of zones, and the controller comprises at least two printed circuit boards, one circuit board containing the second processor and the other circuit board containing the switches.

18. An injection mold comprising:

(a) at least 48 injection stations, each station having at least one heater and at least one temperature sensor, each sensor providing a temperature indicating signal;

(b) a source of current for the heaters;

(c) a controller for controlling the temperature of the station, the controller comprising at least one processor for receiving the temperature indicating signals from the sensors, and an on/off switch for each heater controlling the amount of power going to each heater, the switches being controlled by the processor,

wherein the at least one processor is on a printed circuit board and the switches are on a separate printed circuit board, the temperature signals from up to at least 48 of the injection stations being received by a single processor at a rate of not less than one temperature indicating signal from each temperature sensor per second.

19. The mold of claim 18 wherein the processor receives a signal indicating a measured amount of current flowing to each heater.

20. The mold of claim 18, wherein the controller is within a housing, and wherein the housing is mounted on the mold.

21. The mold of claim 20, further comprising each station having at least one cooling path and a source of chilling fluid for the cooling path;

and the controller also controlling the temperature of chilling fluid provided to the cooling path in response to the received temperature indicating signals.

22. A hot resin injection mold apparatus, the mold having at least forty-eight stations and at least one heater for each station, the apparatus comprising:

(a) at least one temperature sensor in each station, each sensor outputting a temperature indicating signal;

(b) an AC power source generating cycles of an AC wave form providing power to the heaters;

(c) a power driver comprising;

(i) an on/off switch for controlling the power to each heater;

(ii) a transformer for measuring the current to each heater; and

(iii) a zero crossing detector for triggering the on/off switch;

(d) a first processor for receiving the temperature indicating signals comprising;

(i) an AD converter for digitizing the temperature indicating signals; and

(ii) a first microprocessor for computing the RMS of the measured current values and computing the average of the temperature indicating signals; and

(c) a second processor comprising;

(i) data memory for storing a selected range for the temperature in each zone;

(ii) a second microprocessor for performing a PID calculation of the amount of power required to maintain the temperature of each zone within a selected range based on the values computed by the first microprocessor; and

(iii) a zero crossing interrupter for sensing the zero cross-over of the AC wave form and outputting an interrupter signal for signaling the power driver to provide only complete AC cycles to the heaters;

whereby each station is maintained within the selected range of operating temperatures.