Claims
- 1. In a material processing machine having a rotatable cutterhead and a shearbar adjacent thereto for processing material introduced therebetween, acoustic sensor means for sensing contact between he cutterhead and the shearbar, a mechanism for moving the shearbar towards and away from the cutterhead and a control system cooperating with the acoustic sensor means and with the mechanism to automatically adjust clearance between the cutterhead and shearbar, characterized by:
- the acoustic sensor means comprising first and second spaced-apart knock sensors fixed to the shearbar, each generating signals in response to vibrations received thereby; and
- means operable during adjustment of the shearbar-cutterhead clearance for comparing the signal from the first knock sensor to a first threshold, for comparing the signal from the second knock sensor with a second threshold, and for preventing clearance adjustment if either knock sensor signal exceeds its threshold while the other knock sensor signal is less than its threshold.
- 2. The control system of claim 1, wherein:
- the first threshold has a magnitude which is larger than the magnitude of the second threshold.
- 3. The control system of claim 1, wherein the means for comparing and preventing comprises:
- means for generating a first counter value representing the amount of time during which the first knock sensor signal exceeds the first threshold;
- means for generating a second counter value representing the amount of time during which the second knock sensor signal exceeds the second threshold; and
- means for preventing clearance adjustment if either counter value exceeds a first counter threshold while the other counter value is less than a second counter threshold.
- 4. In a material processing machine having a rotatable cutterhead and a shearbar adjacent thereto for processing material introduced therebetween, acoustic sensor means for generating a signal representing vibration of the shearbar, a mechanism for moving the shearbar towards and away from the cutterhead and a control system cooperating with the acoustic sensor means and with the mechanism to automatically adjust clearance between the cutterhead and shearbar, characterized by:
- means for repetitively sampling the sensor signal, for determining a portion of a certain time period during which the sensor signal exceeds a predetermined threshold, and for generating a knock signal representing contact between the cutterhead and shearbar when the determined portion of the certain time period exceeds a reference time period;
- means for sensing rotation of the cutterhead; and
- means for establishing the length of the certain time period as a function of the rotation of the cutterhead.
Parent Case Info
This application is a continuation of application Ser. No. 07/174,069 filed Mar. 28, 1988, now abandoned.
US Referenced Citations (18)
Foreign Referenced Citations (4)
Number |
Date |
Country |
3010416 |
Sep 1981 |
DEX |
3345749 |
Jun 1984 |
DEX |
1187377 |
Apr 1970 |
GBX |
2169181 |
Jul 1986 |
GBX |
Non-Patent Literature Citations (3)
Entry |
John Deere Operator's Manual, p. 24. |
Sperry-New Holland Service Manual. |
E. C. Lundahl, Inc., "Knife Sharpening", 5 Mar. 1980, pp. 173, 34, 234, etc. |
Continuations (1)
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Number |
Date |
Country |
Parent |
174069 |
Mar 1988 |
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