Claims
- 1. A method for controlling a centrifugal machine comprising the steps of:opening a gate of said centrifugal machine to an initial one of a plurality of gate positions between a full closed position and a full open position for entry of charge material into a rotating centrifugal basket of said centrifugal machine; measuring a charge wall thickness forming along inner sidewalls of said rotating centrifugal basket; determining a fill rate at which said charge material enters said rotating centrifugal basket; comparing said determined fill rate to a desired fill rate; opening said gate towards its full open position if said fill rate is less than said desired fill rate; closing said gate towards its full closed position if said fill rate is greater than said desired fill rate so that charge material enters said rotating centrifugal basket at substantially said desired fill rate and controlling the closure of said gate to gradually approach a desired minimum flow rate.
- 2. A method for controlling a centrifugal machine as claimed in claim 1 wherein said desired fill rate comprises a range of fill rates extending from a desired minimum fill rate to a desired maximum fill rate said steps of opening and closing said gate comprises, respectively, the steps of:opening said gate towards its full open position if said fill rate is less than said desired minimum fill rate; and closing said gate towards its full closed position if said fill rate is greater than said desired maximum fill rate.
- 3. A method for controlling a centrifugal machine as claimed in claim 2 further comprising the steps of:comparing said determined fill rate to said desired minimum fill rate and said desired maximum fill rate; incrementing said gate by one position towards said full open position if said determined fill rate is less than said desired minimum fill rate; closing said gate towards said full closed position by at least one position if said fill rate exceeds said desired maximum fill rate; and maintaining said gate position if said determined fill rate is equal to or exceeds said desired minimum fill rate and is less than or equal to said desired maximum fill rate.
- 4. A method for controlling a centrifugal machine as claimed in claim 3 wherein said step of closing said gate comprising the steps of:converting said gate's current position to a gate flow opening; computing a gate desired opening by multiplying said gate flow opening by said desired fill rate with the result being divided by said determined fill rate; and converting said gate desired opening to a new gate position.
- 5. A method for controlling a centrifugal machine as claimed in claim 2 further comprising the step of selecting a desired minimum fill rate of 0.8 inches per second, and a desired maximum fill rate of 1.0 inches per second.
- 6. A method for controlling a centrifugal machine as claimed in claim 1 further comprising the step of selecting said initial one of said plurality of gate positions to be a percentage of said full open position.
- 7. A method for controlling a centrifugal machine as claimed in claim 6 further comprising the step of setting said percentage to 15% of said full open position.
- 8. A method for controlling a centrifugal machine as claimed in claim 6 further comprising the step of setting said percentage to 33% of said full open position.
- 9. A method for controlling a centrifugal machine as claimed in claim 1 further comprising the step of recording a gate full open last position for use in processing the next batch of charge material.
- 10. A method for controlling a centrifugal machine as claimed in claim 9 further comprising the step of recording said gate full open last position immediately prior to entering a pinch mode of operation of said centrifugal machine.
- 11. A method for controlling a centrifugal machine as claimed in claim 10 further comprising the step of:modifying said recorded gate full open last position if said gate opens towards its full open position after recording said gate full open last position.
- 12. A method for controlling a centrifugal machine as claimed in claim 9 further comprising the steps of:opening said gate to a fraction of said full open position if the current cycle of centrifugal processing is the first cycle immediately following a power up or reset condition, otherwise opening said gate to said gate full open last position recorded in an immediately preceding previous cycle of centrifugal processing; and maintaining said gate position until the thickness of charge material in said rotating centrifugal basket of said centrifugal machine exceeds a desired minimum load level.
- 13. A method for controlling a centrifugal machine as claimed in claim 1 further comprising the step of determining said fill rate every 0.8 seconds.
- 14. A method for controlling a centrifugal machine as claimed in claim 1 wherein said step of measuring a charge wall thickness forming along inner side walls of said rotating centrifugal basket is performed every 30 milliseconds.
- 15. A method for controlling a centrifugal machine as claimed in claim 1 wherein said step of measuring a charge wall thickness forming along inner sidewalls of said rotating centrifugal basket of said centrifugal machine comprises the step of using an ultrasonic probe.
- 16. A method for controlling a centrifugal machine as claimed in claim 1 further comprising the step of closing said gate towards said full closed position if wobble in said centrifugal basket exceeds a severity threshold.
- 17. A method for controlling a centrifugal machine as claimed in claim 16 further comprising the steps of:maintaining a wobble severity count of consecutive occurrences of gate closure due to detected wobble; comparing said wobble severity count to a maximum severity count; if said severity count exceeds said maximum severity count performing the steps of: closing said gate to said full closed position; adjusting rotation speed of said centrifugal basket of said centrifugal machine to a minimum speed necessary to to keep the bulk of charge in a walled up position; and initiating an alarm signal if said gate fully closes due to wobble.
- 18. A method for controlling a centrifugal machine as claimed in claim 1 further comprising the step of closing said gate towards its closed position if wobble in said centrifugal basket exceeds a severity threshold and a fill level exceeds a desired minimum load level.
- 19. A method for controlling a centrifugal machine as claimed in claim 18 further comprising the steps of:closing said gate towards said full closed position if wobble in said centrifugal basket of said centrifugal machine exceeds a maximum severity count, and said fill level exceeds said desired minimum load level; adjusting the speed of rotation of said centrifugal basket of said centrifugal machine to a minimum speed necessary to to keep the bulk of charge in a walled up position; and initiating an alarm signal if said gate fully closes due to wobble.
- 20. A method for controlling a centrifugal machine as claimed in claim 1 wherein said step of measuring a charge wall thickness forming along inner side walls of said rotating centrifugal basket is preformed every 60 milliseconds.
- 21. A method for controlling a centrifugal machine as claimed in claim 1 further comprising the steps of:detecting unstabilizing wobble of said centrifugal basket; and if said unstabilizing wobble of said centrifugal basket is detected, closing said gate to a new gate position computed by determining a gate flow opening, decreasing said determined gate flow opening by 20%, and converting said gate flow opening to said new gate position, said gate closing by at least 1 position.
- 22. A method for controlling a centrifugal machine as claimed in claim 1 further comprising the steps of:closing said gate to a position computed by determining a gate flow opening, decreasing said gate flow opening by 20%, and converting said gate flow opening to a new gate position, said gate closing by at least 1 position, if wobble in said centrifugal basket exceeds a severity threshold and said charge wall thickness exceeds a desired minimum load level; closing said gate to said full closed position if wobble of said centrifugal basket of said centrifugal machine exceeds a maximum severity count and said charge wall thickness exceeds said desired minimum load level; adjusting the speed of rotation of said centrifugal basket of said centrifugal machine to a minimum speed necessary to to keep the bulk of charge in a walled up position; and initiating an alarm signal if said gate fully closes due to wobble.
- 23. A method for controlling a centrifugal machine as claimed in claim 1 further comprising the step of monitoring negative apparent feed rates to detect wobble of said centrifugal basket.
- 24. A method for controlling a centrifugal machine as claimed in claim 23 further comprising the step of disabling said wobble detection for a loading cycle if an operator changes said gate full open position.
- 25. A method for controlling a centrifugal machine as claimed in claim 1 further comprising the step of recording said charge wall thickness and said fill rate subsequent to said gate closing.
- 26. A method for controlling a centrifugal machine as claimed in claim 25 further comprising the step of determining a wash time for said charge material based upon said charge wall thickness recorded subsequent to said gate closing.
- 27. A method for controlling a centrifugal machine as claimed in claim 1 further comprising the step of providing an operator reset for said centrifugal machine.
- 28. A method for controlling a centrifugal machine as claimed in claim 1 further comprising the step of providing an operator means for controlling said desired fill rate.
- 29. A method for controlling a centrifugal machine as claimed in claim 1 further comprising the step of providing an operator means for controlling said gate full open position.
- 30. A method for controlling a centrifugal machine comprising the steps of:opening a gate of said centrifugal machine to an initial one of a plurality of gate positions between a full closed position and a full open position for entry of charge material into a rotating centrifugal basket of said centrifugal machine; measuring a charge wall thickness forming along inner sidewalls of said rotating centrifugal basket; determining a fill rate at which said charge material enters said rotating centrifugal basket; comparing said determined fill rate to a desired fill rate; opening said gate towards its full open position if said fill rate is less than said desired fill rate; closing said gate towards its full closed position if said fill rate is greater than said desired fill rate so that charge material enters said rotating centrifugal basket at substantially said desired fill rate; comparing said charge wall thickness to a desired pinch fill level; entering a pinch mode of machine operation upon said charge wall thickness being equal to or greater than said desired pinch fill level; moving said gate from its current position towards a minimum pinch gate opening position while in said pinch mode of machine operation; and maintaining said pinch mode of machine operation until said charge wall thickness reaches a fill at shut level.
- 31. A method for controlling a centrifugal machine as claimed in claim 30 further comprising the step of selecting said minimum pinch gate opening to be a percentage of said full open position.
- 32. A method for controlling a centrifugal machine as claimed in claim 30 wherein said step of moving said gate from its current position towards said minimum pinch gate opening comprises the step of substantially linearly moving said gate from its current position towards said minimum pinch gate opening.
- 33. A method for controlling a centrifugal machine as claimed in claim 30 further comprising the step of selecting said desired pinch fill level to be a percentage of a requested fill level.
- 34. A method for controlling a centrifugal machine as claimed in claim 33 further comprising the step of selecting said desired pinch fill level to be 50% of said requested fill level.
- 35. A method for controlling a centrifugal machine as claimed in claim 30 further comprising the steps of:comparing said determined fill rate to a desired pinch fill rate; incrementing said gate by one position towards said full open position if said determined fill rate is less than said desired pinch fill rate; closing said gate substantially linearly by moving said gate from its current position towards said minimum pinch gate opening if said fill rate is greater than said desired pinch fill rate; and maintaining said gate in its current position if said determined fill rate is substantially equal to said desired pinch fill rate.
- 36. A method for controlling a centrifugal machine as claimed in claim 35 wherein said desired pinch fill rate comprises a range of pinch fill rates extending from a desired minimum pinch fill rate to a desired maximum pinch fill rate.
- 37. A method for controlling a centrifugal machine as claimed in claim 35 wherein said step of closing said gate substantially linearly by moving said gate from its current position towards said minimum pinch gate opening comprises the steps of:converting said gate's current position to a gate flow opening; computing a minimum pinch opening by multiplying said gate flow opening by said pinch fill rate divided by said determined fill rate; setting said minimum pinch opening to a minimum gate flow opening if said minimum pinch opening is less than said minimum gate flow opening; calculating a slope by subtracting said minimum pinch opening from 100; calculating a gate position difference opening using said slope; calculating a gate desired opening by subtracting said gate position difference opening from 100; and converting said gate desired opening to a new gate position.
- 38. A method for controlling a centrifugal machine as claimed in claim 37 wherein said step of calculating said gate position difference opening comprises the step of dividing said slope by a servo fill level with the result being multiplied by the result of said determined fill level less said fill at shut level and plus said servo fill level.
- 39. A method for controlling a centrifugal machine as claimed in claim 35 further comprising the step of selecting said desired pinch fill rate to be a percentage of said desired fill rate.
- 40. A method for controlling a centrifugal machine as claimed in claim 35 further comprising the step of setting said percentage to 33% of said desired fill rate.
- 41. A method for controlling a centrifugal machine as claimed in claim 30 further comprising the step of moving said gate to its fully closed position upon said charge wall thickness reaching said fill at shut level.
- 42. A method for controlling a centrifugal machine as claimed in claim 41 further comprising the step of selecting said fill at shut to be a percentage of a requested fill level.
- 43. A method for controlling a centrifugal machine as claimed in claim 41 further comprising the steps of:comparing a final measured charge wall thickness to a requested fill level; increasing said fill at shut level if said charge wall thickness is less than a requested minimum fill level; and decreasing said fill at shut level if said charge wall thickness is greater than a requested maximum fill level.
- 44. A method for controlling a centrifugal machine as claimed in claim 41 further comprising the steps of:comparing a final measured charge wall thickness to a requested fill level to determine underfill or overfill of said centrifugal basket; increasing said fill at shut level if said centrifugal basket is underfilled for at least one cycle of centrifugal processing; and decreasing said fill at shut level if said centrifugal basket is overfilled for at least one cycle of centrifugal processing.
- 45. A method for controlling a centrifugal machine as claimed in claim 44 wherein said step of increasing said fill at shut level if said centrifugal basket is underfilled for at least one cycle of centrifugal processing comprises the step of increasing said fill at shut level if said centrifugal basket is underfilled for three consecutive cycles of centrifugal processing.
- 46. A method for controlling a centrifugal machine as claimed in claim 45 wherein said step of increasing said fill at shut level if said centrifugal basket is underfilled for three consecutive cycles of centrifugal processing comprises the step of increasing said fill at shut level by an amount equal to the minimum underfill of said three consecutive cycles of centrifugal processing.
- 47. A method for controlling a centrifugal machine as claimed in claim 44 wherein said step of decreasing said fill at shut level if said centrifugal basket is overfilled for at least one cycle of centrifugal processing comprises the step of decreasing said fill at shut level by an amount equal to one half the difference between said final charge wall thickness and said requested fill.
- 48. A method for controlling a centrifugal machine comprising the steps of:opening a gate of said centrifugal machine to an initial one of a plurality of gate positions between a full closed position and a full open position for entry of charge material into a rotating centrifugal basket of said centrifugal machine; measuring a charge wall thickness forming along inner sidewalls of said rotating centrifugal basket; determining a fill rate at which said charge material enters said rotating centrifugal basket; comparing said determined fill rate to a desired fill rate; opening said gate towards its full open position if said fill rate is less than said desired fill rate; closing said gate towards its full closed position if said fill rate is greater than said desired fill rate so that charge material enters said rotating centrifugal basket at substantially said desired fill rate; and closing said gate towards said full closed position in response to sensing an unstabilizing wobble of said centrifugal basket.
- 49. A method for controlling a centrifugal machine as claimed in claim 48 further comprising the step of requiring at least two sample periods to determine wobble.
- 50. A method for controlling a centrifugal machine as claimed in claim 48 further comprising the step of disabling said unstabilizing wobble sensing until said charge wall thickness exceeds a minimum load level.
- 51. A method for controlling a centrifugal machine comprising the steps of:opening a gate of said centrifugal machine to an initial one of a plurality of gate positions between a full closed position and a full open position for entry of charge material into a rotating centrifugal basket of said centrifugal machine; measuring a charge wall thickness forming along inner sidewalls of said rotating centrifugal basket; comparing said charge wall thickness to a desired pinch fill level; entering a pinch mode of machine operation upon said charge wall thickness being equal to or greater than said desired pinch fill level; and moving said gate from its current position towards a minimum pinch gate opening position while in said pinch mode of machine operation by determining a fill rate at which said charge material enters said rotating centrifugal basket; comparing said determined fill rate to a desired pinch fill rate; and moving said gate incrementally through a linear range of gate openings towards said gate full closed position if said fill rate exceeds said pinch fill rate; comparing said charge wall thickness to a fill at shut level; and maintaining said pinch mode of machine operation until said charge wall thickness reaches said fill at shut level.
- 52. A method for controlling a centrifugal machine as claimed in claim 51 further comprising the step of moving said gate to said full closed position upon said charge wall thickness reaching said fill at shut level.
- 53. A method for controlling a centrifugal machine as claimed in claim 51 wherein said step of moving said gate from its current position towards said minimum pinch gate opening comprises the step of substantially linearly moving said gate from its current position towards said minimum pinch gate opening.
- 54. A method for controlling a centrifugal machine as claimed in claim 53 wherein said step of substantially linearly moving said gate from its current position towards said minimum pinch gate opening further comprises the steps of:determining a fill rate at which said charge material enters said rotating centrifugal basket; converting said gate's current position to a gate flow opening; computing a minimum pinch opening by multiplying said gate flow opening by a desired pinch fill rate divided by said determined fill rate; setting said minimum pinch opening to a minimum gate flow opening if said minimum pinch opening is less than said minimum gate flow opening; calculating a slope by subtracting said minimum pinch opening from 100; calculating a gate position difference opening using said slope; calculating a gate desired opening by subtracting said gate position difference opening from 100; and converting said gate desired opening to a new gate position.
- 55. A method for controlling a centrifugal machine as claimed in claim 54 wherein said step of calculating said gate position difference opening comprises the step of dividing said slope by a servo fill level with the result being multiplied by the result of said determined fill level less said fill at shut level and plus said servo fill level.
- 56. A method for sensing unstabilizing wobble of a rotating centrifugal basket of a centrifugal machine comprising the steps of:opening a gate of said centrifugal machine to an initial one of a plurality of gate positions between a full closed position and a full open position for entry of charge material into said rotating centrifugal basket of said centrifugal machine; measuring a charge wall thickness forming along inner sidewalls of said rotating centrifugal basket; determining an apparent feed rate at which charge material enters said rotating centrifugal basket; detecting oscillations in said apparent feed rate; and closing said gate towards said full closed position in response to detecting said oscillations in said apparent feed rate.
- 57. A method for sensing an unstabilizing wobble as claimed in claim 56 wherein said step of closing said gate towards said full closed position further comprising the step of closing said gate towards said full closed position if said unstabilizing wobble in said centrifugal basket exceeds a severity threshold.
- 58. A method for sensing an unstabilizing wobble as claimed in claim 57 further comprising the steps of:maintaining a wobble severity count of consecutive occurrences of gate closure due to detected wobble; comparing said wobble severity count to a maximum severity count; if said severity count exceeds said maximum severity count performing the steps of: closing said gate to said full closed position; adjusting rotation speed of said centrifugal basket of said centrifugal machine to a minimum speed necessary to to keep the bulk of charge in a walled up position; and initiating an alarm signal if said gate fully closes due to wobble.
- 59. A method for sensing an unstabilizing wobble as claimed in claim 57 wherein said step of closing said gate further comprises the step of closing said gate towards said full closed position if wobble in said centrifugal basket exceeds said severity threshold and said measured charge wall thickness exceeds a desired minimum load level.
- 60. A method for sensing an unstabilizing wobble as claimed in claim 59 further comprising the steps of:maintaining a wobble severity count of consecutive occurrences of gate closure due to detected wobble; comparing said wobble severity count to a maximum severity count; if said severity count exceeds said maximum severity count performing the steps of: closing said gate to said full closed position; adjusting rotation speed of said centrifugal basket of said centrifugal machine to a minimum speed necessary to to keep the bulk of charge in a walled up position; and initiating an alarm signal if said gate fully closes due to wobble.
- 61. A method for sensing an unstabilizing wobble as claimed in claim 56 wherein said step of measuring a charge wall thickness forming along inner sidewalls of said rotating centrifugal basket comprises the step of periodically sampling said charge wall thickness, said method further comprising the step of requiring at least two sample periods to determine unstabilizing wobble.
- 62. A method for sensing an unstabilizing wobble as claimed in claim 56 further comprising the step of disabling wobble sensing until said measured charge wall thickness exceeds a minimum load level.
- 63. A method for sensing an unstabilizing wobble as claimed in claim 56 wherein said step of closing said gate further comprises the step of closing said gate to a new gate position computed by determining a gate flow opening, decreasing said determined gate flow opening by 20%, and converting said gate flow opening to determine said new gate position, said gate closing by at least 1 position.
- 64. A method for sensing an unstabilizing wobble as claimed in claim 63 wherein said step of closing said gate further comprises the step of closing said gate by at least one gate position.
- 65. A method for sensing an unstabilizing wobble as claimed in claim 56 wherein said step of closing said gate further comprises the steps of:closing said gate to a position computed by determining a gate flow opening, decreasing said gate flow opening by 20%, and converting said gate flow opening to determine said new gate position, said gate closing by at least 1 position, if wobble in said centrifugal basket is greater than a severity threshold, a maximum severity count has not been exceeded, and said measured charge wall thickness exceeds a desired minimum load level; closing said gate to said full closed position if said unstabilizing wobble exceeds said maximum severity count and said measured charge wall thickness exceeds said desired minimum load level; adjusting the speed of rotation of said centrifugal basket of said centrifugal machine to a minimum speed necessary to to keep the bulk of charge in a walled up position; and initiating an alarm signal if said gate fully closes due to wobble.
- 66. A method for sensing an unstabilizing wobble as claimed in claim 65 wherein said step of closing said gate further comprises the step of closing said gate by at least one gate position.
- 67. A method for sensing an unstabilizing wobble as claimed in claim 56 further comprises the step of monitoring negative apparent feed rates to detect wobble of said centrifugal basket.
- 68. A method for sensing an unstabilizing wobble as claimed in claim 56 further comprising the step of disabling wobble sensing for a loading cycle if an operator changes said gate full open position.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application No. 60/117,980 filed Jan. 29, 1999, which is incorporated herein by reference.
US Referenced Citations (24)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0 894 814 |
Jan 1999 |
EP |
59-92344 |
May 1984 |
JP |
Provisional Applications (1)
|
Number |
Date |
Country |
|
60/117980 |
Jan 1999 |
US |