Measuring conveyor belt stretch
AssigneeLaitram, L.L.C.
InventorsLazlo Kleczewski, Martin A. Benavidez, Jonatan Milde Barales
Life of this patent
Estimating the term…
Abstract
A system and method for measuring the elongation, or stretch, of a modular plastic conveyor belt. The belt-stretch measuring system measures stretch as the ratio less one of an actual belt travel distance or actual belt speed to an expected belt travel distance or expected belt speed for a new, unstretched belt. The actual belt travel distances or actual belt speeds are measured by sensors. The expected belt travel distances or expected belt speeds are calculated from the pulse outputs of encoders measuring the rotation of sprockets engaging the conveyor belt and from the known number of teeth on the sprockets. Actual belt pitch and catenary sag are also calculated.
Claims20
A method for measuring conveyor-belt stretch comprising:
- driving a conveyor belt having a nominal belt pitch in a direction of belt travel along a travel path with rotating sprockets having a predetermined number of sprocket teeth;
- mounting one or more sensors along the travel path;
- determining an actual belt speed or an actual travel distance of the conveyor belt from the detection of a detectable on the conveyor belt with the one or more sensors at a first time and at a later second time;
- determining a corresponding expected belt speed or a corresponding expected belt travel distance from an encoder signal from an encoder measuring the rotation of the sprockets and from the nominal belt pitch and the number of sprocket teeth, wherein the encoder signal is read to get a first encoder reading at the first time and a second encoder reading at the second time;
- determining the expected travel distance of the belt from the difference between the first and second encoder readings;
- calculating a belt stretch from the expected belt speed and the actual belt speed or from the expected belt travel distance and the actual travel distance.
A method for measuring conveyor-belt stretch comprising:
- driving a conveyor belt having a nominal belt pitch in a direction of belt travel along a carryway with rotating first and second sprockets spaced apart a predetermined carryway length at opposite first and second ends of the carryway, wherein the first and second sprockets have a predetermined number of sprocket teeth;
- coupling first and second encoders to the first and second sprockets to produce first and second encoder signals measuring the rotation of the first and second sprockets;
- synchronizing the first and second encoder signals when the conveyor belt is operating at its nominal belt pitch;
- determining the phase shift of the second encoder signal relative to the first encoder signal;
- calculating belt stretch from the phase shift, the nominal belt pitch, and the number of sprocket teeth.
A conveyor-belt stretch measuring system comprising:
- a conveyor belt having a nominal belt pitch advancing along a carryway in a direction of belt travel and engaged with rotating sprockets having a predetermined number of sprocket teeth;
- one or more sensors along the carryway detecting the motion or position of a detectable on the conveyor belt and producing sensor signals at a first time and at a later second time indicative of the motion or position of the detectable;
- an encoder coupled to one of the sprockets and producing encoder signals measuring the rotation of the sprockets at the first time and at the later second time;
- a processor executing programmed instructions to:
- receive the sensor signals and the encoder signals;
- calculate an actual belt speed or an actual travel distance of the conveyor belt from the sensor signals;
- calculate a corresponding expected belt speed or a corresponding expected belt travel distance from the encoder signals and from the nominal belt pitch and the number of sprocket teeth;
- and
- calculate a belt stretch of the conveyor belt from the expected belt speed and the actual belt speed or from the expected belt travel distance and the actual travel distance.
A method for measuring conveyor-belt stretch comprising:
- driving a conveyor belt having a nominal belt pitch in a direction of belt travel along a travel path with rotating sprockets having a predetermined number of sprocket teeth;
- determining an actual belt speed VA with a speed measurement device in rolling contact with the conveyor belt along the travel path or by measuring the speed of a detectable conveyed atop the conveyor belt along the travel path;
- determining a corresponding expected belt speed VE from an encoder signal from an encoder measuring the rotation of the sprockets and from the nominal belt pitch and the number of sprocket teeth;
- calculating a belt stretch S as S=(VA/VE)−1.
Dependencies are inferred from the claim text.