Maintenance and Calibration of SCS-150 Weighing Scale
The weighing scale is an important measuring instrument for our company's foreign trade and one of the main quality measuring instruments for foreign trade. This article mainly introduces the main technical indicators and daily maintenance and calibration methods of the SCS-150 weighing scale.
I. Overview
The SCS series digital weighbridge is an automated weighing device for weighing running or stationary goods, suitable for measuring various trucks and bulk cargo. Our company's SCS-100 type weighbridge consists of a mechanical weighing platform, a digital sensor system, a digital weighing display, etc. It is equipped with facilities such as a weighing body foundation and a control room. When a heavy object or a heavy truck is placed on the weighing platform, under the action of gravity, the weighing platform transfers gravity to the sensor, causing the elastic body of the sensor to deform, complete force/electricity conversion, and output an electrical signal proportional to the weight value. After processing by the weighing instrument, it completes analog/digital conversion, data acquisition, processing, display, etc. It has high precision and reliability;
② Good consistency and interchangeability;
③ High stability;
④ Having self recognition function for easy fault diagnosis;
⑤ Has high flexibility in group naming;
⑥ It has features such as anti blocking function.
2、 Daily inspection, maintenance and main technical parameters of SCS-100 weighing scale:
1. The requirements for technical performance indicators are shown in Table 1:
2. Precautions for use:
(1) The SCS-100 weighing scale should be uniformly placed on the weighing platform, with a speed controlled within 5km/h. Emergency braking is prohibited on the weighing platform, and the vehicle should be parked in the middle of the weighing body as much as possible.
(2) Before each vehicle is loaded onto the weighing platform, observe whether the instrument display shows zero gross weight; Observe whether the instrument display is stable before printing or recording data.
(3) When there is a vehicle on the scale, it is not allowed for the instrument to be powered off. If there is a temporary power outage, the vehicle should be taken off the scale after the power is restored, and the instrument should be re measured after the zero point is restored.
(4) Welding operations or using the scale platform as a ground wire are strictly prohibited on the scale platform.
(5) The load capacity of the vehicle measured each time shall not exceed the maximum weighing capacity.
3. Maintenance precautions
(1) Regularly inspect the limit device of the weighing scale to ensure its accuracy, check whether the weighing body is flexible, and ensure that the longitudinal and transverse limit clearances are 3mm. The limit collision plate and all limit bolts are intact (transverse limit clearance ≤ 2mm, longitudinal limit clearance ≤ 3mm, unloading clearance ≤ 2mm)
(2) Check whether the load-bearing platform is qualified, that is, the diagonal dimensions of the four sensor force points (diagonal error within 4mm), as well as the left-right deviation (within ± 1.5mm) and front back deviation (within ± 2mm) based on the centerline.
(3) When checking the clearance around the scale platform, attention should be paid to whether there are any foreign objects embedded between the edge of the scale and the bottom of the scale body or between the scale body and the slope. The junction box should be cleaned, and the wiring of each sensor cable should be firm, with ABS hex nuts locked tightly;
(4) The column sensor is installed vertically without any tilting phenomenon.
4. Analysis and elimination of common faults
(1) No display or buzzing sound when the instrument is powered on: It may be due to a blown fuse, no 220V AC input, or high voltage breakdown of the instrument transformer. The fuse should be replaced, the 220V AC input should be checked, or a dedicated transformer should be replaced.
(2) There is an angle difference on the instrument display: it may be due to the foundation of the scale being not solid. After long-term use, the height of the sensor base may not be consistent. The angle difference score can be readjusted or the height of the base can be adjusted.
(3) The instrument display shows drift phenomenon: it may be due to long-term water and moisture exposure of the digital sensor, which weakens the insulation performance. The internal code value of each sensor should be checked to determine which sensor has drift phenomenon.
(4) After the instrument is turned on, it performs a self check and displays "......", indicating a system crash. It is possible that the green and white data lines in the junction box are connected incorrectly. The power should be disconnected immediately, and the instrument should be used to check whether all sensor cables and the corresponding color lines of the bus are correct. It should also be tested for any wire collision between them and reconnected.
(5) The large screen display has not shown normal weighing data since power on: the connection method between the instrument interface and the large screen interface is not unified; The table can be connected using the connection method.
(6) After connecting the instrument to the computer, running the weighing software displays garbled code: reset the baud rate in the instrument and weighing software to unify their settings.
(7) After getting off the weighing platform, there is still a relatively large stable data displayed on the instrument panel: check the limit of the weighing platform and adjust it to a reasonable position.
(8) After turning on, the instrument panel keeps displaying relatively large data, and there is a wide range of flicker: unstable voltage or external interference.
3、 Calibration of SCS-150 Weighing Scale
1. Calibration standard (weight)
The error of the standard weights used for verification should not exceed 1/3 of the maximum allowable error of the corresponding scale
2. The division values and maximum allowable error range are shown in Table 2.
3. Verification process
The calibration of SCS-100 weighing scale should comply with the calibration regulations of JJG539-1997 "Digital Indicator Scale", and the specific operation steps are as follows:
(1) Appearance inspection
Check the mark and number of the manufacturing license; The manufacturer, factory number, accuracy level, maximum and minimum weighing, calibration division value, and mark should be firm and reliable, and their handwriting size and shape must be clear and easy to understand.
(2) Repetitive testing
The difference between the results obtained by weighing the same load multiple times should not exceed the absolute value of the maximum allowable error of the weighing.
Starting from zero, add weights in ascending order until the maximum weight is reached. Use the same method to remove weights until the zero point and perform multiple measurements. The measurements should include (minimum weight, maximum allowable error change in weight; 50% maximum weight; maximum weight).
(3) Unbalanced load
The indication error of the same weight at different positions should not exceed the maximum allowable error of the weighing.
① For scales with N ≤ 4 support points on the carrier, the weight applied to each support point is approximately equal to 1/3 of the sum of the maximum weighing and maximum added tare weight
② For scales with N ≥ 4 support points on the carrier, the weight applied to each support point is approximately equal to 1/(N-1) of the sum of the maximum weighing and maximum added tare weight
(4) Discriminative power
On a balanced scale, gently place or remove a weight equal to 1.4d, and the original reading should change.
(5) Zero setting device
The zeroing accuracy of the zeroing device should be within ± 0.25d, and the total zeroing effect of the zeroing device should not exceed 4% of the maximum weighing.
The total effect of the initial zeroing device should not exceed 20% of the maximum weighing capacity.
(6) Accuracy of the zeroing device.
The impact of zero deviation on the weighing result after zeroing should not exceed 0.25e.
(7) Repeat verification
Find the maximum weighing capacity of the vehicle with a total mass greater than or equal to this dynamic weighing scale and repeat the pressure several times, with a deviation not exceeding the maximum allowable error.