DD286737B5 - METHOD FOR DETERMINING THE SHARPNESS OF HAECKSELMESSERN - Google Patents

Abstract

A method of monitoring the sharpness of chaff-cutting blades in chaff-cutting equipment comprises the step of detecting, while the equipment is rotating, voltage pulses induced in a transmitter by the cutting edge and the rear edge of a chaff-cutting blade brushing past. The peak voltages of those pulses are compared with each other by computation and a signal is issued when a predetermined limit value is reached. Since only the cutting edge becomes worn, the ratio of the peak values of the two pulses provides an indication of wear. The values may be processed digitally and a limit value of the ratio detected. The pulses may be produced by a magnetic sensor which may move to monitor the entire cutting face of the blade.

Description

Field of application of the invention

The invention relates to a method for determining the sharpness of chopping knives in the installed state, in particular for forage harvesters. In addition, the method can be applied to all knives, which are mounted on rotating bodies and which are employed to the cutting plane.

Characteristic of the known state of the art

The sharpness of the cutting edges of chopping knives is crucial for the quality of the haulm and the energy demand of the shredder. This connection is particularly important for the high-performance self-propelled forage harvesters. But especially for forage harvesters, the determination of the sharpness of the chopper knives is very difficult due to the structural conditions, since so far only a subjective assessment by visual inspection in conjunction with the experience of the operator are used. Checking the chopping blades is therefore always associated with a shutdown of the machine and causes downtime. Due to the poor accessibility to the chopper blades at the same time create considerable accident hazards.

Due to the different seed properties of the harvested crop, attempts to assess the drive performance of the Hariislor Hjn Schärfe dftr chopper knife have not been successful.

Object of the invention

The aim of the invention is to provide a method for determining the sharpness of chopping knives, with which the instantaneous sharpness of the chopper knife can be objectively determined without loss of time and accident hazards of the operator are excluded.

Darling of the essence of the invention

Dur invention is based on the object, a method for determining the sharpness of chopping knives in the installed state, especially for forage harvesters, the Häckselmescer are provided on a rotatably mounted body to Schneidobene to create, with the operation during the operation of the shredder dio sharpness without intervention dor operator can be accurately detected

 According to the invention this is achieved by

a) continuously or at intervals during operation with rotating chopper the detected in a donor by the cutting edge and the trailing edge of a passing chopping knife induced positive and negative voltage pulses are detected and offset against each other;

b) upon reaching a fixed limit value of the calculated voltage values, in particular the peak voltage ratio, a signal for the operator is triggered, operated a stop device or a grinding device is put into operation.

The invention is based on the fact that due to the wear of the cutting edge Jm sharply employed chopper blade of the induced voltage pulse reduced by the formation of a radius in its absolute size and changed in shape. By contrast, the voltage pulse due to the trailing edge in the cutting plane remains constant since no wear occurs here. Since two geometrical shapes are compared with each other, are measured directly one after the other and belong to one component, and the same sensor is used for this purpose, the method works free of disturbances, environmental influences and in many areas independent of speed and distance. This makes it possible to use a erfindungsgomäß working device universally.

According to the invention, it is desirable that the peak stress ratio be determined and stored on sharp chopper knives, and that the signal be triggered when the ratio of peak stress ratios on sharp chopping knives and instant chipper knife state reaches a specified limit.

Ultimately, it is expedient that for the measurement electrical, non-contact, pollution-resistant donors, especially fast donors are used on the inductive and magnetic principle. The limit value is determined by experiments from Schneidkantenverschleißzustand, where the quality of the shredded material decreases sharply and dor the energy requirement of the forage harvester increases inadmissible. The limit is entered as a constant to the system.

In an embodiment of the invention, a second encoder may be used which marks a fixed point on the periphery of the chopper. Thus, it is possible with a first timer downstream pedometer to obtain a statement about each individual knife. If the first encoder is moved parallel to the cutting plane, then the chopper sharpness can be determined over the entire chopping blade length.

With the inventive solution on the one hand, the availability of shredders are increased, on the other hand decreases by improving the cutting ability due to the timely regrinding the chopping knife in conjunction with a corresponding adjustment of the cutting gap to the fixed counter cutting the energy needs of the chopper. By the information to the operator via display means on the control unit, the invention ultimately leads to the reduction of accident hazards.

Ausführungsboispiol

The invention will be explained in more detail with reference to an exemplary embodiment.

At a grinding device of a chaffing device, a magnetic Gebor is mounted mechanically protected at a small distance from the rotating shell of the chopper drum. If one of the obliquely chopped blades passes the magnetic field of the encoder, a positive voltage pulse is induced for the submersion of the acute-angled cutting edge. This is measured by a peak meter and stored for a short time. When the chopper leaves the magnetic field of the encoder, a negative voltage pulse is induced by the trailing edge. This is also measured and stored. Since the trailing edge of the chopping blade forms an obtuse angle, the peak value of this voltage pulse is smaller, and in its shape it is shallower than the voltage pulse caused by the cutting edge. The two stored peak values are forwarded to an analog-to-digital converter and preprocessed as digital values in a computer. A voltage value ratio formed therefrom can be displayed directly to the operator as a numerical value or a knife sharpening symbol. The numerical values or symbols express the wear state of the cutting edge, and boim falls below a certain Zahlonwertes must be reground.

It is also possible to evaluate the positive and negative voltage peaks analog, by means of a logarithmic and differential amplifier and to give a signal to the driver when falling below a specified limit or to use the signal simultaneously for further control operations for automatically grinding the chopping blades and setting the Gegenschnaide , If the grinding device with the attached encoder is moved transversely to the chopper drum, then the sharpness of the chopper knife is distributed over its length.

Claims (5)

1. A method for solidifying the sharpness of chopping knives in the installed state, in particular for forage harvesters, wherein the chopping blades are employed on a rotatably mounted body to the cutting plane, characterized in that a) continuously. At intervals during operation with a rotating chopper, the positive and negative voltage pulses induced in a sender by the cutting edge and the trailing edge of a passing chopping knife are detected and offset against each other; b) upon reaching a fixed limit value of the calculated voltage values, in particular the peak voltage ratio, a signal for the operator is triggered, operated a stop device or a grinding device is put into operation. 2. The method according to claim 1, characterized in that the peak tension ratio is determined in sharp Hecker knives and the signal is triggered when the ratio of peak voltage ratios in sharp chopping knives and the current chopper state reaches a specified limit. 3. The method according to claim 1, characterized in that non-contact electrical encoder, in particular magnetic or inductive sensors, b ^ be used. 4. The method according to claim 1, characterized in that a cutting plane invariable point of the chopping device is detected with a second encoder. 5. The method according to claim 1, characterized in that the encoder parallel to the cutting plane übör the entire length of the chopper knife can be moved.