JPH0418672Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Field of Application> The present invention relates to an improvement in an acoustic measuring means for a crusher that uses a signal based on generated sound as a measurement value representing a load state.

<Prior art> Fig. 3 is a configuration diagram showing an example of the conventional technology.
For example, this is a technique known from Japanese Patent Application Laid-open No. 159855/1983. Clinker, which is a material to be crushed, is charged into the ball mill 1 from a belt scale 2, and the crushed clinker is transferred to a separator 4 by a bucket elevator 3.

The ball mill 1 is divided into two chambers 1a and 1b, and the sound generated from each chamber is transmitted through a microphone 5.
a, 5b, amplification and inversion processing are performed by amplifiers 6a, 6b, and the measured values x ₁ , x ₂
It is input to the adder 7 as .

The adder 7 inputs these acoustic signals x ₁ and x ₂ as well as the measured value x ₃ of the power sensor 8 of the bucket elevator 3, and calculates the measured value PV ₁ representing the clinker load condition as follows.

PV ₁ =k ₁ x ₁ +k ₂ x ₂ +k ₃ v ₃ +k ₄ where k ₁ to k ₄ are constants that can be set arbitrarily.

9 is a main controller that controls the clinker input amount, executes control calculations for the deviation between the measured value PV ₁ and the set value SV ₁ , and outputs the manipulated output MV ₁ as the cascade set value SV ₂ of the slave controller 10. send.

The slave controller 10 inputs the measured value PV 2 of the transfer amount sensor ₁₁ of the belt scale 2 and the manipulated output of the main controller 9 as a cascade set value SV ₂ , performs a control calculation on the deviation, and outputs the manipulated output MV _2. is transmitted to the belt scale drive device (not shown) to control the clinker input amount to _SV2 .

FIG. 4 is a characteristic curve showing the change in grinding efficiency when changing the mill load, that is, PV _1. In the solid curve F ₁ , the maximum efficiency is P ₁ when PV ₁ = C ₁ , so The set value SV ₁ of the main controller 9 has a value PV ₁ of P ₁
It is set to the optimal value such that

However, the grinding speed changes due to disturbance factors such as the hardness and size of the clinker, water sprinkling inside the ball mill, temperature fluctuations, and wear of the steel balls, and the efficiency characteristic curve shifts as shown by the chain line F ₂ and F ₃ . However, since the maximum efficiency point also shifts like P ₂ and P ₃ , it is necessary to constantly change the set value in order to operate at the maximum efficiency point.

12 is an automatic correction means for the set value _SV1 . Grinding efficiency can be expressed by the amount of clinker input to the ball mill, that is, the time integrated value of PV ₁ or MV _1. For example, when the set value SV ₁ is increased by a certain value, the integrated value of PV ₁ for a certain time before the increase Compare the integrated value for a certain period of time after the increase, and if the integrated value has increased, increase the set value by a certain value, and then compare the integrated value again. If the integrated value has decreased, increase the set value. On the other hand, by repeating the comparison of the integrated value after reducing it by a certain value, the set value SV ₁ is automatically corrected so that the amount fed into the ball mill is always the maximum.

<Problems to be solved by the invention> The feature of this type of control device is that it measures the condition of the mill load using the generated sound, but the microphone used as a sound collection means has a certain degree of directivity. However, although a suitable filter means is used in the amplifier to remove ambient noise other than the mill and noise generated by the mill itself that is unrelated to load condition parameters, the noise removal effect is not sufficient. However, it has the disadvantage of being unreliable as a measured value.

The present invention aims to provide a control device that can solve these problems.

<Means for Solving the Problems> The structural features of the present invention include a sound collection means for the sound generated by the crusher, and an FFT (Fast Fourier・Transform) means, weighting calculation means that weights and adds each spectrum output of this FFT means, and the output of this calculation means is taken as a measurement value representing the load condition, and the deviation between this measurement value and the set value is calculated. A controller that controls the raw material supply amount of the crusher based on the control-calculated operation output, and monitors changes in the output of the controller or the measured value of the raw material supply amount when the set value is changed, The point is that the set value is changed and controlled so that the measured value is maximized.

<Function> According to the present invention, the sound pressure signal of the sound collecting means is FFT
The means decomposes the frequency spectrum into groups of frequency spectra, and each spectrum output is weighted and summed.

This weighting process makes it possible to extract only signals related to the effective sound generated by the mill as measured values.

<Example> An example of the present invention will be described based on FIG. Components that are the same as those explained in FIG. 3 are given the same reference numerals, and the explanation thereof will be omitted.

13a and 13b are FFT means, which transform the amplifier output into respective spectrum signals f ₁ and f ₂ as shown in FIG.
... decomposes into f _o-1 and fn. This FFT means is widely used as a measurement means for general frequency analysis as a software package.

14a and 14b are weighting calculation means, which add weights to the necessary spectrum and unnecessary noise spectrum, and calculate the measured values x ₁ and x ₂ as follows. a ₁ to an are weighting coefficients.

x ₁ (x ₂ ) = a ₁ f ₁ + a ₂ f ₂ ... + f _o-1 a _o-1 + fnan±b To identify which spectrum is the effective frequency component or noise component, check the spectrum under actual operating conditions. The weighting coefficients may be set after confirming each site by conducting an investigation such as stopping surrounding sound sources while monitoring.

Next, the specific configuration of the automatic setting value correction means 12 will be explained. Reference numeral 121 denotes a sequence control means, which executes the entire sequence of correction operations.

122 is a calculation holding means for the set value SV ₁ , and 123 is a value obtained by integrating the measured value PV ₂ from the transfer amount sensor 11 of the belt scale 2 for a certain period of time after changing the set value.
The integrated value storage means 124 for holding Sn is a storage means for the integrated value S _o-1 for a certain period of time of PV ₂ before the set value is changed, and the stored content Sn of the integrated value storage means 123 is shifted by the sequence control means 121. It is what was done.

Reference numeral 125 denotes a subtraction means, which calculates the difference ±ΔS between the integrated value Sn of the integrated value storage means and S _o-1 .

The result of this calculation is guided to the direction detection means 126 to determine the direction of increase or decrease in the integrated value, and a direction signal d is transmitted to the sequence control means 121.

127 is a dividing means, which calculates the ratio of increase/decrease in the integrated value to the previous integrated value - ΔS/S _o-1 and transmits it to the set value calculating means 122 .

The set value calculation means 122 adjusts the amount of change in the second and subsequent set value changes based on the output of the division means 127 according to the rate of increase or decrease in the integrated value, according to a command from the sequence control means 121.

In this way, by adjusting the amount of change in the set value according to the rate of change in the integrated value, the amount of change decreases as the maximum efficiency point is approached, and when the maximum point of efficiency is maintained, the amount of change decreases. It is possible to perform a corrective operation to make the value zero, which has the advantage of improving controllability compared to a method that constantly changes a constant value.

Next, additional components will be explained. 15
is the mill clogging detection means, and the measured value of adder 7
It has a function to issue a mill clogging alarm MVa when PV ₁ exceeds the alarm set value SVa.

Reference numeral 16 denotes a changeover switch means for operating the main controller 9 using only the measured value x ₃ of the power sensor 8 of the bucket elevator, and is driven by a sequence control means 18 operated by a changeover command switch 17. . Reference numeral 19 denotes a control constant changing means, which is also driven by the sequence control means 18, and changes the P, I, and D control constants of the main controller to appropriate values when operating with only the measured value _x3 .

20 is a limiter for the operation output MV ₂ of the slave controller;
21 is a manual changeover switch, and 22 is a manual operation output transmitting means.

<Effects of the invention> As explained above, according to the invention, it is possible to select and measure only the sounds related to the grinding efficiency of the mill from the various sounds generated by the mill itself and the sounds of machinery around the mill. It becomes possible to improve the reliability of the control device that operates at maximum efficiency.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an output waveform diagram of the FFT means, FIG. 3 is a block diagram showing an example of the prior art, and FIG. 4 is an explanatory diagram of its operation. 1...Ball mill, 2...Belt scale, 3
... Bucket elevator, 5a, 5b ... Microphone, 6a, 6b ... Amplifier, 7 ... Adder, 8 ... Power sensor, 9 ... Main controller, 10
...Subordinate controller, 11...Transfer amount sensor, 12...
...Automatic correction means, 13a, 13b...FFT means,
14a, 14b... Weighting calculation means.

Claims (1)

[Scope of utility model registration request] A sound collection means for the sound generated by the crusher and decomposition of the sound pressure signal of this sound collection means into frequency spectrum signals.
FFT (Fast Fourier Transform)
a weighting calculation means that weights and adds each spectral output of the FFT means; and an operation in which the output of this calculation means is used as a measurement value representing the load condition, and the deviation between this measurement value and a set value is controlled and calculated. A controller that controls the amount of raw material supplied to the crusher based on the output, and a change in the output of the controller or the measured value of the raw material supplied amount when the set value is changed, and the measured value is A pulverization control device characterized by changing and controlling the above-mentioned set value so as to maximize the value.