1 Accuracy control of weighing elements
Before the belt scale is installed, its basic elements are strain gauge load cells,
Accuracy control of belt speed sensor and belt scale electronic unit is in laboratory
Under conditions in accordance with the metrological characteristics of sufficient legal and regulatory requirements. used to weigh
The load cell of the heavy building is according to the "quality standard electromechanical belt sensor metering strip"
test to the metrological characteristics defined in the Component Rulebook, which complies with sufficient
international standard conditions. The test of the load cell used in the belt weighing ceremony is in the
over the entire operating temperature range of the weighing instrument (-10°C to +40°C), because
Therefore, the scale is considered accurate if the error is within the specified error range.
Tests are: measurement accuracy, hysteresis, repeatability, output signal at minimum load due to temperature
temperature changes, the output signal changes due to changes in air pressure at the lowest load, negative
Output deviation when load creep and load position change. Characterization test of speed sensor
In the whole speed measurement range (standard is 0.01-10m/s), and the whole working
Within the operating temperature range, the measurement error must be within the error range recommended by OIMLR50.
Loading is checked by measuring the impulse of the runner with a known belt length
and slippage of friction pulleys with no belt loaded.
2 Belt scale installation
2.1 The working principle is systematic, and then weighed and measured through the electronic belt scale. Put the object displayed on the belt scale
Compare and adjust the weight of the material with the indicated weight of the physical verification device, so as to achieve
To the purpose of calibrating the belt scale. In order to ensure the accuracy of the physical verification results, the actual
The physical calibration device itself is equipped with standard weights for calibration of its own accuracy. Every
For the first time, before the physical calibration, the weight is lifted by the weight hoist, and the weighing indicator
The displayed value should be the same as the weight value of the lifted weight; otherwise, the weighing indicator should
The table is corrected to ensure the weighing accuracy of the physical verification device.
2.2 Check the accuracy of belt scale installation
According to the technical documents and installation instructions, the accuracy of the belt weighing device is different from that of some
The position, installation method and connection of the weighing element are related, including the measurement of the weighing device
Specific elements of the system and belt conveyor sections that do not represent part of the measurement system
pieces. When installing the belt scale, it is necessary to test: Whether the position of the weighing device is in accordance with the obtained
Conditions for maximum accuracy (alignment and eccentricity of weighing idlers, etc.), weighing idlers
Anti-corrosion and clogging protection of the group, whether the conveyor belt is strong enough to withstand the static load
(The movement resistance of the weighing idler group and the friction resistance of the belt edge to the beam, the dynamic
Loading (driving, lifting, transporting, moving along rollers, pulleys, changing direction, etc.), belts
Is there any inclination, slipping, etc. Bearing rollers, if there are instructions, the director lazy man will add
The belt set on the loading end is expected to slip off the belt on both sides of the belt, whether the quality is
The length of the conveyor belt per meter is constant along its entire length and where the belt joins the
To what extent does it affect the weighing result, the change in the moving speed of the weighing belt,
This rate must not exceed 5% of the nominal differential value, i.e. the transmission of the established value
The speed of the belt, whether the belt is stretched has nothing to do with the temperature, wear, load, belt and drive
Sliding between the driving pulleys, if the belt length exceeds 10m, the idler roller being weighed
group, as a force conveyor, must have an angle of not less than 90° at the point of contact with the belt
The bending of the belt, when the belt load exceeds the maximum allowable load, it acts as overload protection
With or without auxiliary devices, such as belt cleaning devices, etc., it does not affect the weighing results. remove
In addition to the inspection of the mechanical connection method, a mechanical connection is also required. According to the existing technology
Technical documentation and weighing power supply, testing of the electrical connection of the belt weighing part of the components
Accuracy, that is, the accuracy of protective grounding.
3 Scale zero adjustment
The function test of the balancer is to determine whether the elements and control elements of the weighing instrument are
Whether the projection function is realized, check the weight input parameters: the change of load and speed, the actual
The expected change in the current output value. At the same time, the zero setting and automatic calibration function of the scale are also checked.
able. Setting the weighing to zero greatly affects measurement accuracy because this error
The difference is continuously integrated into the measured mass flow. The zero deviation of the belt scale is determined by
For: zero deviation of the force sensor, preload of the weighing platform and conveyor belt, weighing
Susceptibility of similar parts to the input level of the electronic unit, and due to temperature and weather
Drift caused by atmospheric influence. Setting the zero position of weighing is after its installation,
The loaded weighing machine was tested before and after. If the conveyor belt does not run for a long time
(more than 2 hours), then zero reset is performed 15 minutes after the transport system is started to
Support system to keep the conveyor belt in the running position. By applying additional hardware and
Software-controlled automatic belt weighing, the display of the weighing value is blocked until a certain value is reached.
a stable temperature. The setting of the weighing zero position is to run at a constant speed on the unloaded conveyor belt
When carried out, and within the minimum zero test period recommended by the technical manual,
For automatic zero setting, the control interval is 3 minutes or a full revolution of the conveyor belt
period, depending on the length of time. The test of scale zero stability includes a set of control procedures,
The procedure is repeated until, in three consecutive tests, it is determined that the error does not exceed
0.06% of full scale capacity or 1 of belt scale (depending on which is smaller). weighing
Zero deviation can be expressed as a reference level, a percentage of the full belt capacity
Or the change in full load during a full revolution of the belt. After the weighing load test is completed
Repeat zeroing if zeroing error exceeds 0.12% of full belt scale capacity or 2
degrees with a scale (depending on the smaller fact), then the repeat test is considered to be
positive. Modern belt scales have the possibility of automatic zeroing. The auto-zero algorithm is in the
It is carried out periodically during the measurement process. When the measurement process is temporarily stopped, there is a measurement
The measurement parameter allows detection of potential deviations from the zero point of the weight. auto-zero software-initiated
The prerequisite is to set the error limit of the maximum load percentage, such as: two consecutive
The limit difference of zero adjustment (can be in the range of 0-10% of the maximum load, generally the maximum
within 0.5% of maximum load), the average of two consecutive zero adjustments (range: 0 -
1 0% of max. load, typically 1% of max. load), zero of error setting limit
Maximum value (typically 5% of maximum load can be scaled up to 100% of maximum load,
The load cell must therefore be adjusted to work over a wider range than marked on the device.
do ). The result of the automatic zeroing is presented as a tare correction (kg/m) per
Over-set limit values are represented in an appropriate manner. Duration of the zero test
The interval is calculated from the belt length and the measured moving speed, or set by the software
order (most commonly on the order of a few hours a foot).