There is a close connection between the installation, debugging, and use of electronic car scales. This article combines practice to discuss several experiences and insights on the installation, debugging, and accuracy adjustment technology of a 60 ton electronic truck scale.


1、 Installation of electronic car scales


The installation of electronic car scales should first have a suitable and spacious site, and ensure that the foundation has a large bearing capacity. The height of the bearing point must be on a horizontal plane.


1. Requirements for bearing capacity on foundation.


(1) To construct according to different regions and situations, the bearing capacity of each bearing point must be greater than the maximum overload that may occur during the measurement process. Taking the 60 ton electronic truck scale as an example, the self weight of its load-bearing platform is 10 tons, and when the rear axle of the truck is fully loaded, it is 50 tons. Assuming an overload of 1.25 times, the impact load coefficient when the upper load-bearing platform is 1.3, that is, the maximum load for each load-bearing point is: W=1/2 (50t x 1.25 x 1.3+1/2 x 10)=43.125t. During the foundation construction process, it is best for several load-bearing building structures to be in the same overall structure. Generally, It is also possible to build two load-bearing points on a concrete foundation, and the bearing capacity of each foundation must not undergo individual sinking changes under stress.


(2) The load-bearing capacity of the longitudinal and transverse anti-collision piers is relatively small, and can be manufactured according to the dimensions given in the foundation drawing. The longitudinal impact force is relatively large. Taking the 60 ton electronic car scale as an example: the maximum load of the car is M1=60t x 1.25=75t=75000kg, and the load-bearing platform is M2=10000kg. The car speed is (maximum) ν 1=10km/h. υ= υ 1=x=2.45m/s The function of the same load-bearing platform for cars is: W=1/2mv2=1/2 (75000+10000) x (2.45) 2=255106.25m/s2 The force acting on each longitudinal anti-collision pier is P==26031.25kg. The above method can be used to calculate the force magnitude of a single longitudinal anti-collision pier for various car scales. 2. Basic requirements for the level and height of key points.


In order to ensure small installation errors and high accuracy of the weighing instrument, the following requirements are required for the load-bearing points: the levelness of a single load-bearing platform should be within 1/500, and the height error between each load-bearing point should not exceed ± 3mm. The following methods can be used to achieve the above requirements.


(1) When constructing the load-bearing foundation of electronic car scales, reserve holes should be made according to the dimensions on the drawings for each load-bearing point.


(2) When installing, first use concrete to support the sensor's load-bearing plate and anchor bolts, with the load-bearing block level as the reference ± 0
Fix at the lower dimension. After 24 hours of concrete, adjust the bearing plate so that the levelness of a single bearing plate reaches 1/500, and the height difference between each bearing point does not exceed ± 3mm.


Due to the fact that most electronic car scales currently produced are pit type and lack facilities such as protective sheds, the foundation surface must have good drainage capacity. Generally, the foundation surface is constructed with a slope of 1/200 to facilitate drainage to the drainage ditches on both sides, with each bearing point 50mm to 70mm higher than the surrounding foundation surface.


3. Overall requirements for load-bearing platforms.


The electronic car scale requires that the bending of the 125% weighing scale body at full load should not exceed 5mm, and the two sides of the scale platform require high-strength bolts to have a certain torque with the scale body (bolt strength is 4.6 level).


4. The weighing sensor is subjected to vertical pressure.


Before installing the weighing sensor, the pressure head and the weighing sensor should be placed in a balanced and vertical position on the reference plane to avoid the influence of lateral forces.


5. Limitations on the swing of the load-bearing platform.


Electronic car scales must limit the amount of swing caused by the load-bearing platform on the vehicle to ensure accurate measurement. The temperature range for the use of electronic car scales is -10 ℃ to 40 ℃, with a temperature difference of 50 ℃. The linear expansion coefficient of steel is 11.4 × 10-6 L/℃. Taking the 60t electronic car scale as an example: its load-bearing platform is 14.5m long, 3.5m wide, 14500 x 11.4 x 10-6 x 50=8.265mm, 3500 x 11.4 x 10-6 x 50=1.995mm. Therefore, the lateral clearance is 1.5mm, and the maximum longitudinal clearance is 4mm.


6. Correct connection of cables.


The wiring between the weighing display and sensors should be connected according to the wiring diagram in the random file. It is particularly important to note that when multiple sensors are used in parallel, their cable lengths should be consistent to ensure consistent resistance values, and signal cables cannot be arbitrarily shortened or lengthened. Because when the signal cable is long, it will affect the supply bridge voltage and affect the output signal voltage. The general length of signal cables is 8m to 10m. 2、 After the debugging and installation of the electronic car scale, check whether the connections of various parts of the scale body are intact. The scale body should not come into contact with any part of the foundation, and the distance between the scale body and the surrounding edge iron is 10mm to 15mm. Before debugging, it is necessary to turn on the power switch and preheat for 15 minutes. Use a vehicle with a load capacity close to the maximum scale as much as possible, pass back and forth multiple times, and brake on the load-bearing platform. Use a torque wrench to tighten the high-strength bolts of each weighing sensor.


1. Use a digital voltmeter to sequentially measure the output voltage of each weighing sensor. If there is any inconsistency, adjust the corresponding two precision adjustable resistors in the junction box to reduce the difference between them. But the adjustment amount must be noted that the rotation direction of the two adjustable resistors should be the same, and the rotation direction should be the same
The rotational speed should also be the same. When rotating clockwise, the resistance decreases, the output voltage increases, and the displayed value increases. Otherwise, the opposite is true. Until the output of each weighing sensor is adjusted to be consistent. Debugging can generally be carried out using the weight method, which involves placing 1/10 of the maximum weight on the center of the load-bearing platform and on the load-bearing platform above each weighing sensor, and accurately measuring the difference in output of each weighing sensor using the real difference method. At the same time, adjust the two precision adjustable resistors of each weighing sensor at each load-bearing point to reduce the difference between them, but the rotation direction and amount are also the same.


2. After debugging, evenly add the weight equivalent to the maximum scale to the load-bearing platform. Follow the positions and methods introduced in the instructions of various weighing displays to ensure that the displayed value is consistent with the weight value. Then, remove the weight and confirm that the empty scale displays "0". Finally, divide the maximum scale into several parts, which must include the minimum and maximum scales of the scale, as well as each weighing point with a change in tolerance. It is required that the weighing error at each point does not exceed the maximum tolerance requirement for each weighing point.


3. Refer to the user manual (professional technical manual) of the weighing display, check the correctness of various function keys, and improve the weighing accuracy of the electronic car scale.