GB2235118A

GB2235118A - A method of monitoring the sharpness of chaff-cutting blades

Info

Publication number: GB2235118A
Application number: GB9017628A
Authority: GB
Inventors: Gerd Friese; Uwe Hoefgen; Klaus Schulze; Burkhard Weiss
Original assignee: AGRITECHNIK ING BETRIEB
Current assignee: AGRITECHNIK ING BETRIEB
Priority date: 1989-08-11
Filing date: 1990-08-10
Publication date: 1991-02-27
Also published as: FR2650723A1; GB9017628D0; DD286735A5; DE4023113A1; CS395490A3

Abstract

A method of monitoring the sharpness of chaff-cutting blades of chaff-cutting equipment comprises the steps of contactlessly determining the proportion of the blade surfaces lying in a cutting plane relative to the total rotational surface when the blades are sharp and while the chaff-cutting equipment is rotating, storing the determined proportion, determining this proportion anew during operation of the equipment, comparing the instantaneous proportion with the stored proportion, and generating a signal, for example to cause regrinding of the blades, when a fixed limit value is fallen below.

Description

A METHOD OF MONITORING THE SHARPNESS OF CHAFF-CUTTING BLADES The present

invention relates to a methodof monitoring the sharp ness of chaff-cutting blades, especially blades installed in field chaff cutters.

The sharpness of the cutting edges of chaff-cutting blades in chaff cutters is critical for the quality of the chaff and the energy consumption of the chaff cutter. This relationship is particularly important in powerful automotive field chaff cutters. However, ascertaining the sharpness of the blades is made difficult by the constructional conditions, since hitherto only a subjective judgement by visual check in combination with:the experience of the operator were used. Checking of the blades therefore always requires taking the mahine out of operation and thus causes standstill times. Due to the poor accessibility to the blades, there may also be appreciable risks of accident.

Due to the different cutting properties of crops, attempts to judge the sharpness of the blades by reference to the driving power of the chaffcutter have not led to success.

There is thus a need for a method of ascertaining the sharpness of chaff-cutting blades, by which method the instantaneous sharpness can be determined objectively without loss of time or exposure of the operator to risk of accident. Preferably, the method should permit sharpness to be detected exactly during the operation of the chaff cutter without action by the operator.

According to the invention there is provided a method of monitoring the sharpness of chaff-cutting blades arranged on a rotatable body and set against a cutting plane in chaff cutting equipment, the method comprising the steps of contactlessly determining, during rotation of the body and when the blades are sharp, the proportion of the blade surfaces in the cutting plane relative to the total rotational area in the plane, storing the determined proportion as a reference value, contactlessly determining, continuously or periodically, the instantaneous value of said proportion during operation of the equipment, comparing each such instantaneous value with the reference value, and generating a-signal when the instantaneous value falls below the reference value by more than a predetermined amount.

In a preferred example of the method, while te chaff-cutting equipment is rotating the proportion of the chaff-cutting blade surfaces lying in the cutting plane to the total rotational area lying in the cutting plane in the case of sharp chaffcutting blades is determined contactlessly and stored,this proportion is determined anew continuously or at intervals during the operation of the chaffcutting equipment, the stored proportion measured for sharp chaffcutting blades is compared with the proportion determined in operation, and a warning for the operator is initiated, stop equipment is actuated or grinding equipment is set into operation when a fixed limit value of the reduction in this proportion is fallen below.

The geometric change in the chaff-cutting blades set obliquely against the cutting edge is utilised for the determination of the sharpness. The length of the blade surface lying in the cutting plane reduces with increasing wear of the cutting edge. In terms of measurement technique, this wear can be determined by detection of the proportion of length or time of this blade surface to the total 0 v 111 1 circumference or to the total measuring time, respectively. The measurement values can be fed to an electronic unit with storage capacity for further preparation. Preferably, electrical contactless transmitters which are insensitive to contamination, in particular rapid transmitters of the inductive or magnetic principle, are used for the measurement.

The limit value can be determined in field trials from the state of wear of the cutting edges at which the quality of the chaff falls to an unacceptable level and the energy consumption of the chaff cutter rises substantially. This limit value is fed as a constant to the electronic unit.

By means of a method exemplifying the invention, the utilisation time of the chaff cutter may be increased and its energy consumption reduced as a Qonsequence of improvement in the cutting capability due 15. to:timely regrinding of the chaff-cutting blades in conjunction with appropriate setting of the cutting gap relative to the stationary counterblade. Through supply of information to the operator by way of indicating means in the driver cabin, there may also be a reduction in the risks of accident.

An example of the method of the invention will now be more particularly described in relation to chaff-cutting equipment of a field chaff cutter. In this equipment, a rapid inductive initiator is arranged at a small spacing above the envelope of rotation of a chaff cutting drum. In the case of sharp chaff-cutting blades of the drum, for example after grinding, the length proportion is determined with the drum rotating forwardly as a time proportion of the passage of the blades below the initiator to:the total measuring time and is stored in an electronic unit. The initiator then controls a gate circuit which leads the pulses of a frequency generator to a counter. The blade cutting edge supplies the start signal and the rear edge of the blade surface lying in the cutting plane supplies the stop signal for the pulse count. A second counter detects the total measuring time pulses, wherein the counting results are divided, evaluated in respect of exceeding a predetermined and fixedly stored limit value and stored after the measurement.

During operatiion of the chaff cutter, this measurement is repeated at intervals of time and indicated symbolically to the operator as actual state of the cutting edges. When the comparison ratio has fallen due to the chaff-cutting blade proportion becoming smaller relative to the programmed limit value, an acoustic and optical warning signal is generated to request the operator to stop the working process and regrind the blades.

In combination with known arrangements for automatic grinding and counterblade setting, the entire process can be automated in that the initiated signal by -itge-If or with operator participation is utilised for stopping of the chaff-cutter with a dwell time for the preparation of the already taken-up crop, the switching-on of the grinding equipment and the subsequent setting of the counterblade.

v - 5

Claims

1. A.method of monitoring the sharpness of chaff-cutting blades arranged on a rotatable body and set against a cutting plane in chaff cutting equipment, the method comprising the steps of contactlessly determining, during rotation of the body and when the blades are sharp, the proportion of the blade surfaces in the cutting plane relative to the total rotational area in the plane, storing the determined proportion as a reference value, contactlessly determining, continuously or periodically, the instantaneous value of said proportion during operation of the equipment, comparing each such instantaneous value with the reference value, and generating a signal when the instantaneous value falls below the reference value by more than a predetermined amount.

2. A method as claimed in claim 1, comprising the step of applying the signal to activate warning means for an operator of the equipment.

3. A method as claimed in claim 1, comprising the step of applying the signal to activate means for stopping the equipment.

4. A method as claimed in claim 1, comprising the step of applying the signal to activate means for sharpening the blades.

5. A method as claimed in any one of the preceding claims, wherein each of the steps of determining comprises determining the time proportion of the blade surfaces relative to a total measurement time.

6. A method as claimed in any one of the preceding claims, wherein the steps of determining are carried out with use of electrical contactless transmitting means.

7. A method as claimedinclaim 6, the transmitting means comprising 5 inductive transmitters.

8. A method as claimed in claim 1 and substantially as hereinbefore described.

1 Published 1991 atThe Patent Office. State House. 66/71 High Holborn. LondonWCIR47P. Further copies maybe obtained from Sales Branch, Unit 6. Nine Mile Point Cwmfelinfach, Cross Keys. Newport. NPI 7HZ. Printed by Multiplex techniques ltd. St Mary Cray, Kent.