Compression test systems and methods
View Patent ↗A system and method for determining the compressive strength of pellets are presently disclosed. A system includes a moveable feed tray adapted to support a plurality of pellets to be tested, a platen below the moveable feed tray and opposite a ram capable of applying compressive force to a pellet, a drive motor engaging the moveable feed tray, and a compressive force monitoring system including a force sensor. A method includes providing a feed tray and positioning a ram at a first position above a platen, advancing the feed tray to position a pellet at a test position between the ram and the platen, detecting the non-arrival of the pellet at the test position, retracting the ram from the first position, advancing the feed tray and operating the ram to determine the compressive strength of the pellet. Also disclosed is a calibration method for a compression test system.
1. A system for determining the compressive strength of pellets comprising:
a moveable feed tray adapted to support a plurality of pellets to be tested,
a platen positioned below the moveable feed tray,
a ram opposite the platen, wherein the ram is configured to apply a compressive force to a pellet on the platen,
a drive motor engaging the feed tray to position a pellet between the platen and the ram to permit compression testing of the pellet, and
a compressive force monitoring system including a force sensor, the compressive force monitoring system configured to provide a first signal corresponding to the force applied by the ram to a pellet on the platen and configured to determine the maximum compressive force applied by the ram to the pellet on the platen.
2. The system for determining the compressive strength of pellets as claimed in claim 1 , where the ram is hydraulically powered.
3. The system for determining the compressive strength of pellets as claimed in claim 1 , where the moveable feed tray is a rotating feed wheel.
4. The system for determining the compressive strength of pellets as claimed in claim 3 , where the feed wheel includes a plurality of apertures spaced along the circumference of the feed wheel, each aperture being adapted to support a pellet.
5. The system for determining the compressive strength of pellets as claimed in claim 4 , where the feed wheel has at least 100 apertures adapted to support pellets.
6. The system for determining the compressive strength of pellets as claimed in claim 1 , where the force sensor comprises a load cell.
7. The system for determining the compressive strength of pellets as claimed in claim 1 , where the compressive force monitoring system includes a signal processor for determining the maximum compressive force applied to the pellet on the platen.
8. The system for determining the compressive strength of pellets as claimed in claim 7 , where the signal processor determines the maximum compressive force applied to the pellet on the platen by analog peak capture.
9. The system for determining the compressive strength of pellets as claimed in claim 1 , where the moveable feed tray further comprises a position indicator.
10. The system for determining the compressive strength of pellets as claimed in claim 9 , where the position indicator has a plurality of position indicating apertures, each position indicating aperture corresponding to a pellet support aperture of the feed tray.
11. The system for determining the compressive strength of pellets as claimed in claim 10 further comprising:
a position detection system configured to detect the position of the feed tray, the position detection system having a light source on one side of the feed tray position indicator and an optical sensor opposite the light source on the other side of the feed tray position indicator, where the optical sensor receives light from the light sensor passing through a position indicating aperture when the feed tray is in a desired position.
12. A method for determining the compressive strength of pellets comprising:
providing a feed tray adapted to support a plurality of pellets to be tested,
positioning a ram at a first position above a platen to apply a compressive force to a pellet on the platen,
advancing the feed tray to position a pellet at a test position between the ram and the platen,
detecting the non-arrival of the pellet at the test position,
retracting the ram from the first position,
advancing the feed tray to position the pellet beneath the ram, and
operating the ram to determine the compressive strength of the pellet.
13. The method for determining the compressive strength of pellets as claimed in claim 12 , where the step of detecting the non-arrival of a pellet further comprises:
starting the advance of the feed tray and measuring the time the feed tray has been advancing to position a pellet at the test position between the ram and the platen, and
identifying the non-arrival of the pellet at the test position when the measured time exceeds a predetermined time.
14. The method for determining the compressive strength of pellets as claimed in claim 12 , where the step of advancing the feed tray further comprises advancing the feed tray to position a pellet at a test position between the ram and the platen until the ram in the first position interferes with an advancing pellet supported by the feed tray impeding the advance of the feed tray.
15. The method for determining the compressive strength of pellets as claimed in claim 12 , where the step of retracting the ram from the first position comprises retracting the ram from the first position such that the ram does not interfere with the advancing pellet supported by the feed tray.
16. The method for determining the compressive strength of pellets as claimed in claim 12 further comprising:
retracting the ram from the first position by a predetermined distance,
advancing the feed tray to position the advancing pellet at the test position,
detecting the non-arrival of the pellet at the test position, and
repeating until the ram is sufficiently retracted from the first position such that the ram does not interfere with the pellet supported by the feed tray.
17. A method of calibrating a compression test system comprising
providing a compression test system having a platen engaging a first load cell and a ram opposite the platen,
removing the platen of the compression test system,
providing a second load cell with a known measurement accuracy above the first load cell,
providing a calibration load applicator and a thrust bearing between the second load cell and the ram, the calibration load applicator being extendable to apply a calibration load to the compression test system, and
calibrating the first load cell by comparing the force measured by the second load cell with the force measured by the first load cell.
18. The method of calibrating a compression test system of claim 17 , where the calibration load applicator is a threaded connector.
19. A calibration system for calibrating a load cell of a compression test system, the calibration system comprising:
a master load cell positioned above the load cell of the compression test system, and
a calibration load applicator and a thrust bearing positioned between the master load cell and a ram of the compression test system,
where the calibration load applicator is extendable to apply a calibration load to the compression test system.
20. A calibration system for calibrating a load cell of a compression test system of claim 19 , where the calibration load applicator is a threaded connector.