FR2650724A1 - METHOD FOR CONTROLLING THE EDGE OF STRAW KNIVES - Google Patents

Abstract

A method characterized in that continuously, or at intervals during operation, while the chopper device is rotating, positive and negative voltage pulses induced in a transmitter by the cutting edge and the trailing edge of the cutter. a straw chopping knife passing in front of this transmitter, are detected and counted together; when a fixed limit value of the voltage values thus counted, in particular of the ratio of peak voltages, is reached, a signal is sent to the operator, a stop device is actuated, or else a sharpening device is activated in service. Methods of controlling the sharpness of chopper knives are disclosed.

Description

"Process for controlling the edge of straw chopper knives."

  The invention relates to a method for controlling the edges of straw chopper knives, in particular in chopper pickers, when these knives are mounted on the machine. In addition, the method can be implemented for all the knives which are fixed on rotary basic structures and

  which are set in relation to the cutting plane.

  The sharpness of the edges of the chopping knives

  straw is decisive in the chopper for the quality of the chopped product and for the energy consumption of the chopper. This consideration is particularly important in the case of high powered self-propelled chopper pickers. But precisely, in the case of chopper collectors, the control of the cutting edges of the chopper knives is made very difficult, due to the construction characteristics, although until now, we have been content with a subjective evaluation by visual control in conjunction with operator experience. The control of straw chopper knives is therefore always linked to the machine being taken out of service and resulting in downtime. Due to the poor accessibility to chopper knives, we have

  at the same time significant risk of accidents.

  Due to the different cutting characteristics of the harvested products, research to assess the sharpness of the chopper knives through the driving power of the

straw chopper, did not succeed.

  The object of the invention is to create a method for controlling the cutting edges of straw chopping knives, by means of which the cutting edges of straw chopping knives can be determined objectively at a given time without loss of time, while the risks operator accidents

are excluded.

  The problem posed by the invention is to create a method for controlling the cutting edges of straw chopper knives, in particular for chopper pickers, when these knives are mounted on the machine, and when they are adjusted relative to the cutting plane in being fixed on a rotating base structure, this process making it possible to detect, in a precise manner, the state of the cutting edges during the operation of the straw chopper without intervention

operator physics.

  This problem is solved, in accordance with the invention, in that: a) continuously, or alternately during operation, while the straw chopper device is in rotation, the positive and negative voltage pulses induced in a transmitter by the cutting edge and the rear edge of a straw chopper knife passing in front of this transmitter, are detected and counted together, b) when a fixed limit value of the voltage values thus counted down, in particular of the ratio of the peak voltages , is reached, a signal is sent to the operator, a stop device is activated or a sharpening device is put

in service.

  The invention starts from the fact that, due to the wear of the cutting edge on the sharp straw chopper knife, the absolute magnitude of the induced voltage pulse is reduced and the shape of this pulse

  is changed as a result of the formation of rays.

  The tension pulse due to the rear edge located in the cutting plane remains, on the other hand, constant,

  because there is no wear at this location.

  As two geometric shapes are compared together which are measured immediately one after the other and which belong to the same component part, and that the same transmitter is used for this purpose, the method is free of disturbances, insensitive to the influences of environment and is largely independent of rotation speed and distance. Therefore, it is possible to implement universally, a device operating in accordance with the invention. According to the invention, it is advantageous to determine and memorize the ratio of the peak tensions for sharp chopper knives and the signal is emitted when the ratio of the ratio of the peak tensions for sharp chopper knives and for the condition of the straw chopper knives

  given time, reaches a fixed limit value.

  Finally, it is advantageous to use for measurement electrical transmitters operating without contact insensitive to pollution, in particular fast transmitters operating according to the inductive and magnetic principle. The limit value is then determined by tests from a state of wear of the cutting edge for which the quality of the chopped product leaves much to be desired while the energy consumption of the straw chopper increases unacceptably. This limit value is entered into the system as a constant. In carrying out the invention, it is possible to use a second transmitter which locates a point not

  changeable on the periphery of the chopping device

  Straw. It is thus possible with a step-by-step counter

  not connected following the first transmitter to obtain information on each individual knife. If the first transmitter is moved parallel to

  on the cutting plane, the edge of the chopping knives

  straw can be controlled over the entire length of

knives.

  Thanks to the solution according to the invention, on the one hand, the availability of the straw chopper is increased and, on the other hand, the energy consumption of the straw chopper is reduced due to the improvement of the ability to cut as a result of timely resharpening of the straw chopper knives in conjunction with an appropriate adjustment of the cutting interval with respect to the fixed counter knives. Thanks to the information provided to the operator, via display means at the switching station, the invention also brings about a reduction

risk of accidents.

  The invention will be explained in more detail

  below with reference to an exemplary embodiment.

  On a sharpening device of a straw chopper device, a mechanically protected magnetic transmitter is attached to a reduced distance by

  relative to the rotation envelope of the chopper drum

  Straw. When one of the oblique straw chopper knives crosses the magnetic field of the transmitter, a positive voltage pulse is induced when the cutting edge is penetrated at an acute angle. This pulse is measured by a device for measuring the peak value and stored for a short period. When the straw chopper knife leaves the magnetic field of the transmitter, a negative voltage pulse is induced by its rear edge. This pulse is also measured and stored. As the rear edge of the straw chopper knife forms an obtuse angle, the peak value of this voltage pulse is smaller and its shape is flatter than that of

  the voltage pulse caused by the cutting edge.

  The two peak values thus stored are transmitted to an analog-digital converter and they are processed as digital values in a computer. A report of tension values formed therefrom can be given to the operator, directly as count values or as symbols of the cutting edge of the knife. The count values or symbols express the state of wear of the cutting edge and when crossing a determined count value downwards, it is necessary to

re-sharpen.

  It is also possible to exploit the values of positive and negative voltage peaks in an analogical manner by means of logarithm formation in differential amplifiers, and when a fixed limit value is crossed downwards, to give a signal to the conductor, or at the same time use the signal for other control processes to allow automatic sharpening of the chopper knives and the adjustment of the opposing cutting edges. If the sharpening device with the transmitter mounted on it is moved transversely to the straw chopper drum, the edges of the straw chopper knives distributed over

  the length of this drum are controlled.

Claims (5)

RESELL I CATIONS   1.- Process for controlling the cutting edge of straw chopper knives, in particular for chopper pickers, while these knives are mounted on the machine, and are adjusted relative to the cutting plane on a basic structure mounted so as to be able to turn , process characterized in that: a) continuously or alternately during   operation while the chopping device   straw is in rotation, positive and negative voltage pulses induced in a transmitter by the cutting edge and the rear edge of a chopper knife passing in front of this transmitter, are detected and counted together, b) when a limit value fixed voltage values thus counted down, in particular the ratio of peak voltages, is reached, a signal is sent to the operator, a stop device is actuated or a sharpening device is put in service.   2.- Method according to claim 1, characterized in that the peak tension ratio is determined for sharp straw chopper knives and the signal is issued when the ratio of   peak tension reports for chopping knives   sharpened straw, and for the condition of these chopping knives   straw at a given time, reaches a fixed limit value. 3.- Method according to claim 1, characterized in that electric transmitters operating without contact are used in particular   magnetic or inductive transmitters.   4.- Method according to claim 1, characterized in that a point, invariable relative to the cutting plane, of the straw chopper device is detected with a second transmitter.   5.- Method according to claim 1, characterized in that the transmitter can be moved parallel to the cutting plane over the entire length of the straw chopper knife.