JPS5835097B2 - Baul Mill - Google Patents

Description

[Detailed description of the invention] The present invention relates to a bowl mill for crushing solids such as coal.

A conventional bowl mill will be explained based on FIG. 1.

The bowl 1 is formed in the shape of a rotatable dish with an upwardly open slot forest provided inside the housing 2, and its lower end is supported by a thrust bearing, and the bowl 1 is connected to the electric pinion 5 and the rotary gear 3.
It is driven by a drive motor 4 via.

An umbrella-shaped roll 6 is provided that can rotate in contact with the slotted inner surface of the bowl 1, and a rotating shaft 7 attached to the roll 6 is fixed at one end to a rotating support 9 that is pivotally supported by a pin 8. has been done.

Note that a plurality of rolls 6 are provided, and usually three rolls are provided.

The roll 6 is attached to the other end of the rotating support 9, and the bowl 1 is attached to the other end of the rotating support 9.
A load spring 10 is provided to press against the inner surface.

A coal tweeter 11 is provided at the top of the bowl 1, into which coal lumps are thrown.

A classifier (separator) 12 is provided in the form of a hopper in the upper center of the bowl 1, and a coarse powder collection port 13 is provided in the lower end.
is open, and a coal feed 14 is opened at the upper end and communicates with a burner, etc. (not shown).

Further, a plurality of tangential holes 15 are opened on the upper side.

The air supply port 16 opens downward into the housing 2 .

A bowl mill that crushes coal uses a bowl 1 and an electric motor 4.
Coal (approximately 1" square size) supplied from the coal feeder 11 located at the top of the bowl 1 is lumps of coal) are caught between bowl 1 and roll 6 and crushed.

The pulverized coal becomes pulverized coal, which is blown in the -F direction within the housing 2 by air (hot air) supplied from the air supply port 16.

The blown pulverized coal is carried into the interior of the classifier 12 from the tansel shaft 15 on a swirling flow, and the coarse powder is separated and descends inside the clan firer 12 again, and is sent from the lees powder collection port 13. It is fed onto bowl 1.

The pulverized coal carried by the air flow is supplied from the coal feed 14 to the coal burner of the boiler and burned in the furnace.

In such a bowl mill, the coal supplied to the bowl mill contains hard ashes or iron ingots (collectively called trump iron), and when this is caught between bowl 1 and roll 6, it drives bowl 1. Excessive transient stress is generated on the vertical drive shaft of the electric motor 4, the drive pinion 5, and the rotating gear 3, which in extreme cases may lead to breakage.

For this reason, it is desirable to remove the tramp iron contained in the coal before supplying it to the Baur mill, or to use coal with less tramp iron, but this is extremely difficult from a practical and technical point of view.

Therefore, the present invention indirectly detects the amount of trump iron that has entered the bowl mill during operation of the bowl mill and is caught between the bowl and the roll, and from this detection result, if there is an abnormally large amount of tramp iron that is caught, In this case, a warning will be issued to the operator, and if the tramp iron is extremely jammed, the mill will automatically stop (trip) and prevent excessive fluctuations in the vertical drive shaft and related equipment such as reduction gears. A bowl mill is provided which is equipped with a device to prevent the application of stress.

Next, the present invention will be explained based on a first embodiment based on FIGS. 2 and 3.

In FIGS. 2 and 3, a journal 22 protrudes from one end of a rotating support 9 supporting a roll 6, an electromagnetic core 23, and a coil 24, forming a differential transformer. The displacement gauge 21 is attached, but the displacement type 21
Any device may be used as long as it can detect the angle at which the pin 8 is rotated.

The displacement meter 21 includes a differential transformer amplifier 25 and a high-pass filter 26.
, a first Schmidt circuit 27 and a first monostable multivibrator 28 are connected in series.

A shunt resistor 30 is provided to detect the electric motor 4 drive current and convert it into a low voltage output signal, and the shunt resistor 30 and
An amplifier 31 that amplifies the low voltage output signal generated in the shunt resistor 30, and a second circuit that inputs the output signal of the amplifier 31 and outputs a pulse when the input voltage is below a certain level, and cuts it when it is lower than that. A second monostable multivibrator 3 inputs the outputs of the Schmitt trigger circuit 32 and the Schmitt trigger circuit 32 and converts them into a signal with a constant pulse width and constant voltage.
3 are connected in series.

The respective pulse outputs of the monostable multivibrators 28 and 38 are input to each of the skewer-stable multivibrators 28 and 33, and the pulses are output only when pulses are input at the same time. Furthermore, the AND circuit 34 is connected to a counting circuit which inputs the output of the AND circuit 34, counts it, and outputs the output to the alarm circuit 36 when the count value exceeds a preset count value. The outputs of an AND circuit 34 and a counting circuit 35 are input, and the output is connected to an alarm circuit 36 which is connected to an alarm buzzer 37, an indicator light 38, and an alarm relay 39.

The rest is the same as the conventional Baul mill.

The journal 22 displacement of the Baur mill is converted into a differential transformer (LvD
The measured displacement measured by a displacement meter 21 such as T) is converted into a corresponding voltage signal by a differential transformer amplifier 25.

The journal displacement indicates the thickness of the foreign matter caught between the bowl and the roll, and if there is no tramp iron, it will be a relatively stable DC signal that is approximately proportional to the amount of coal fed from the feeder, but if the tramp iron is caught, it will be a relatively stable DC signal. A spike-like displacement signal (the roll is pushed up so that the gap between the bowl and the roll momentarily increases) is generated.

Therefore, the jar corresponding to the interval between bowl rolls
A Schmitt trigger circuit that guides the differential transformer output signal corresponding to the null displacement to the Schmitt trigger circuit 27 via a high-pass filter 26 (cuts the DC component and passes only the high-frequency pulse signal corresponding to the playing card iron). 2
7 generates an ON output when the input signal exceeds a predetermined voltage, and generates an OFF output when the input signal falls below a predetermined voltage (a kind of comparator).The output of the Schmitt trigger circuit 27 is connected to a monostable multivibrator 28 (one-shot multi). converts one input pulse into a signal with constant voltage and constant pulse width (waveform shaping).

Further, when the playing card is bitten, the resistance between the bowl 1 and the roller 6 increases, and this increases the load on the drive motor 4 via the vertical drive shaft, reduction gear, etc., and increases the drive current.

Therefore, by detecting this motor drive current, amplifying it with an amplifier 31, performing pulse conversion (waveform shaping) in the same manner as the journal displacement signal, and comparing the results with an AND circuit 34, it becomes possible to reliably detect a playing card iron.

Also, this detected playing card iron signal is sent to a counting circuit 35.
By integrating the stress and inputting it into the alarm circuit 36, it becomes possible to estimate excessive repetitive stress on the drive shaft, gears, etc., and it becomes a guideline for the fatigue limit, which prevents damage to equipment and ensures operational safety of the mill.

Although it is possible to capture only the displacement signal of the differential transformer provided in the differential transformer 22 and input it directly to the counting circuit 35 without passing it through the AND circuit 34, this may pick up noise in each circuit and cause uncertain malfunctions. There are things to do.

FIG. 4 shows examples of waveforms in each of the above circuits.

The journal displacement is detected by the differential transformer 21, and the output waveform of the variable transformer amplifier 25 to which the signal is input is waveform a.

The point where the peak value appears is when the tramp iron is biting.

(The size of the playing card iron is 25 pieces of coal in advance.)
Since it is sorted into 11t11L square pieces and supplied into the mill, the peak voltage also corresponds to a displacement of 10 to 20 mm.

) This signal is passed through the high-pass filter 26 to remove the DC component and only the fluctuation component is output and shaped into a waveform.

In the Schmitt trigger circuit 27 to which the above waveform is input, the preset threshold level g
A pulse signal C is output which is ON when the level is higher than the same level g, and OFF when it is lower than the same level g.

The monostable multivibrator 28 to which the pulse signal C is input converts one pulse into a rectangular wave d having a constant amplitude and a constant pulse width.

The rectangular wave d is input to one input terminal of the AND circuit 34.

On the other hand, the motor current is detected by the shunt resistor 30, and the output across the shunt resistor has a waveform e.

In this case as well, the point where the peak value appears is when the trump iron bites, similar to the waveform a above.

This waveform e is amplified by an amplifier 31 to become a waveform f.

The above waveform f is input to the Schmitt trigger circuit 32 and compared with a preset threshold level g', and if it is thicker than the same level g', it is turned on, and if it is smaller, it is turned off.
Outputs F pulse signal.

The above pulse signal is input to a monostable multivibrator 33 and converted into a rectangular wave i of constant amplitude and constant width.

When this rectangular wave i is input to the other input terminal of the AND circuit 34, the AND circuit 34 outputs ON only when the rectangular waves d and i overlap each other in the ON state. A pulse waveform j is output.

Therefore, the state when the playing card iron is caught can be detected by focusing on the fact that the displacement of the roll in the mill and the change in the current of the electric motor occur simultaneously.

For mills in which it is not possible to attach a displacement meter to the roller or journal portion, tramp irons can be detected by simply detecting the motor drive current.

In this case, the output of the monostable multivibrator 33 is
It is sufficient to directly input it to the counting circuit 35 or the alarm circuit 36.

In addition, by changing the set value of the Schmidt level, the size of the playing card iron can be determined, and based on this value and the frequency of appearance, it is possible to prevent equipment from exceeding the allowable values for the fracture stress and fatigue limit of the equipment. I can drive safely.

As described above, the present invention is not limited to this embodiment, but includes a bowl that is rotated by an electric motor via a reduction gear, and a plurality of rolls that cooperate with the bowl to crush substances.
The bowl mill is equipped with an energizing means for pressing the roll against the bowl, and an amplifier that detects and amplifies the current of the electric motor, and a pulse signal that extracts a signal above a certain level using human power from the output of the amplifier. The feature is that a foreign matter trapping monitoring device is visible, which consists of a Schmitt trigger circuit for conversion and a counting circuit that inputs the output of the Schmitt trigger circuit. We proposed a method to indirectly detect the amount of trump iron that is inserted, and from this detection result, if there is an abnormally large amount of tramp iron jammed, a warning will be issued to the driver. If there is a lot of jamming or the frequency of jamming increases, the mill will automatically stop (trip) to prevent excessive fluctuating stress from being applied to the vertical drive shaft and related equipment such as reduction gears, which could lead to damage. In addition, the present invention includes a bowl that is rotated by an electric motor via a reduction gear, a plurality of rolls that cooperate with the bowl to crush a substance, and an urging means that presses the rolls against the bowl. A bowl mill equipped with a displacement meter that detects the amount of displacement of the roll in the pressing direction, a filter that cuts the DC component in the output signal of the displacement meter, and a signal that exceeds a certain level among the output signals of the filter. a first monostable multivibrator circuit that inputs the output signal of the first Schmitt trigger circuit and amplifies it into a pulse of a constant width;
an amplifier that detects and amplifies the current of the electric motor; a second Schmitt trigger circuit that uses the output of the amplifier as input, extracts a signal above a certain level and converts it into a pulse signal; ) A second monostable multivibrator circuit that inputs the output of the IJga circuit and converts it into a pulse of a constant width, and inputs the output pulse signals of the first and second monostable multivibrator circuits, and simultaneously It is characterized by being equipped with a foreign matter jamming monitoring device consisting of an AND circuit that outputs a pulse signal to an alarm and a counting device only when two pulse signals are input. This system directly and indirectly detects the amount of playing card iron that is present, and reliably detects the presence of foreign objects, thereby preventing damage to the equipment.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view of a conventional bowl mill, FIGS. 2 and 3 are diagrams showing the first embodiment, and FIG. 4 is a diagram showing signals output from each means shown in FIG. 3. It is a graph. 1... Baul, 2... Housing, 3
...Rotating gear, 4...Electric motor, 5
... Drive pinion, 6 ... Roll, 7
... Rotating axis, 8 ... Pin, 9 ...
... Rotating support body, 10 ... Loading spring, 1
1... Coal feeder, 12... Graphfire, 13... Coarse powder collection port, 14...
...Call feed, 15...Tangentialian"], 167'...Air supply port, 21...
...Displacement meter, 22...Journal, 23...
... Electromagnetic core, 24 ... Coil, 25 ...
... Differential transformer amplifier, 26 ... High-pass filter, 27, 32 ... Schmitt trigger circuit, 2
8, 33... Monostable multivibrator, 29
... Rectifier smoothing circuit, 30 ... Shunt resistor, 31 ... Amplifier, 34 ... Theory product circuit, 35 ... Counting circuit, 36...
Alarm circuit, 37...Buzzer, 38...
Indicator light, 39... Alarm light

Claims (1)

[Claims] 1. A bowl rotated by an electric motor via a reduction gear, and a plurality of rolls that cooperate with the bowl to crush a substance;
The bowl mill is equipped with an energizing means for pressing the roll against the bowl, and an amplifier that detects and amplifies the current of the electric motor, and the output of the amplifier is used as input to extract a signal above a certain level and convert it into a pulse signal. A bowl mill characterized in that it is equipped with a foreign matter jamming monitoring device consisting of a Schmitt trigger circuit for conversion and a counting circuit for inputting the output of the Schmitt trigger circuit. 2. A bowl that is rotated by an electric motor via a reduction gear, and a plurality of rolls that work together with the bowl to crush materials;
In a bowl mill equipped with an energizing means for pressing the roll against the bowl, there is provided a displacement meter for detecting the amount of displacement of the roll in the pressing direction, a filter for cutting a DC component in an output signal of the displacement meter, and a filter for cutting a DC component in an output signal of the displacement meter. A first Schmitt trigger circuit that extracts a signal of a certain level or higher from the output signal of the circuit and converts it into a pulse signal, and a first Schmitt trigger circuit that inputs the output signal of the first Schmitt trigger circuit and amplifies it into a pulse of a certain width. a monostable multivibrator circuit, an amplifier that detects and amplifies the current of the electric motor, and a second Schmitt trigger circuit that uses the output of the amplifier as input, extracts a signal above a certain level, and converts it into a pulse signal; a second monostable multivibrator circuit that inputs the output of the second Schmitt trigger circuit and converts it into a pulse of a constant width;
, the output of the second monostable multivibrator circuit, and an AND circuit that inputs the pulse signal and outputs the pulse signal to the alarm and counting device only when two pulse signals are input at the same time. Baul mill is characterized by being equipped with a monitoring device.