What is the loader weighing system
Wheel loaders are mounted on the front of the chassis, which are composed of a moving arm, a connecting rod mechanism and a loading bucket. They are self propelled earth moving machines for shoveling, transporting, unloading and leveling operations. If the corresponding work device is replaced, it can also carry on the earth, lifting, loading and unloading of wood and so on. It is a very widely used engineering machine.
Since the major loader, short wheelbase, and always in the mobile operation state, it is difficult to use the fixed position of its cargo weighing weighing, otherwise it will affect the work efficiency, therefore, find a way to make it in the work process to complete the method of weighing goods, in order to solve this problem. Generally, the higher the accuracy of the goods measurement, the weighing error generally requires about 0.1% ~ 0.5%. When wheel loaders carry out bulk cargo loading, the weight of the goods is calculated by the method of weighting line drawing at the beginning. This method has the characteristics of large error, large randomness and inconvenient management. Multi loading will cause direct economic loss and overload transport; less load less, will reduce transport efficiency and damage the interests of customers. At the same time, because of the loading machine without weighing device and the material handling must rely on car transport or use weighing loadometer, low handling efficiency costs are high. With the development of railway, automobile, port, wharf and other logistics, the demand for loading efficiency, safety and accuracy is getting higher and higher. An advanced loader weighing system is needed to realize the automatic and accurate measurement of goods in the loading process. It has a significant effect on strengthening the management of loading operations, preventing overload and under loading, improving the efficiency and efficiency of loading and unloading operations, and ensuring the safety of vehicle transportation.
Introduction of weighing system
The working principle of loader weighing system:
Loader weighing system is generally divided into two parts, signal acquisition part and signal processing and display part. The signal acquisition part is usually realized by sensors or transmitters, and the accuracy of signal acquisition is crucial to the accuracy of the loader's weighing.
Static weighing system
It is often used to refit existing loaders or forklifts. Due to the fact that there are no proper weighing devices at the scene, and users need to measure for trade settlement, the static metering method is usually used in view of users' need for reassembly cost. The static measurement weighing device is composed of pressure sensors (1 or 2, depending on the accuracy requirement) + normal weighing display instrument (when necessary, can be selected for printers) + installation accessories (pressure pipe or process interface, etc.).
The general characteristics of static weighing:
1), in each weighing, the position of the weighing hopper is consistent, in order to ensure the accuracy of the weighing, thus affecting the weighing efficiency.
2), the function of the equipment is less, and many work needs to be done by hand, such as record, calculation, etc.
3), it is suitable for short-term workplace, and does not need a large amount of data processing.
4), low cost, suitable for some individual business units or small units.
5), the parameters involved are few, and it is convenient to install and debug.
Dynamic weighing system
The dynamic weighing system should be selected for the loading measurement of large units such as stations and ports so as to meet the needs of rapid, continuous measurement and large amount of data management. Dynamic weighing equipment mainly includes: pressure sensor (2) + dynamic control instrument (with printing function) + installation accessories.
The main features of the dynamic weighing equipment are as follows:
1), accumulative loading, weight setting, display and overweight alarm function;
2), weighing and accumulating and displaying function of single bucket weight;
3), freight vehicle type selection or input function, vehicle number input function;
4), the operator, the loader number and the input function of the station code.
5), the working time (year, month, day, time, minute) recording function;
6), the function of basic data storage, printing and inquiry.
7), dynamic sampling and fuzzy algorithm are used to realize dynamic calibration and dynamic weighing, without stopping the bucket and weighing automatically in the process of lifting.
8), use the loader power supply.
9), using dual hydraulic sensor and high precision A/D converter, the precision is higher.
10), the automatic zero or manual zero can be set.
Scope of application
It is suitable for automatic weighing metering, overload protection and workload management of loaders (including shovels). It can be weighed coal or coke, colored ore, earthwork, granite or marble, sand, crushed stone brick, industrial and civil waste, excavating material and building material. Application sites: wheel loaders, such as mines, stations, ports, wharfs, factories, freight yards and so on.
Selection of sensors
According to the operation characteristics of loaders, there are three kinds of signal acquisition parts: weighing sensor, pressure (oil pressure) sensor and pressure (oil pressure) transmitter. One thing to stress is that sensors have better performances such as overload protection, vibration resistance, insulation and anti-interference.
The A. weighing sensor is generally used to replace the pin shaft with the sensor at the same time to achieve the goal of weighing. The scheme requires higher sensor size and accuracy in structure design and installation. Therefore, in practice, there are often bad phenomena such as low accuracy, inconvenience in installation and replacement, and even safety accidents.
The B. pressure (oil pressure) sensor completes the weighing operation by changing the liquid pressure to the weight of the loading bucket. It is convenient and quick to retrofit. The accuracy of the device is greatly improved compared with the use of the weighing sensor, and the safety performance is guaranteed.
C. (hydraulic pressure) transmitter, the sensor output is mV signal and small signal in the transmission and processing of susceptible to interference, numerate weight prone to error, relatively high on the display part of the request, in the weighing accuracy requirements is difficult in the system is relatively high. The transmitter solves these problems very well. It has strong anti-interference ability and large output signal (usually 4~20mA or 0-10VDC, 0-5VDC), which greatly reduces the requirement of signal processing part and display part, and the accuracy of weighing system is also enhanced.
Under D., two pressure sensors and transmitters, which are suitable for loaders or shovel weighing devices, are introduced.
Sputtering thin film pressure sensor
This product is designed by using the technology of sputtering thin film and the design of loader weighing system. It is mainly used to measure the oil pressure of the loader and convert it into the weight signal.
F> 1), the main features of the product:
G> a, small volume, light weight, can be installed directly.
B, high precision and good long-term stability.
C, good shock resistance, impact and overload ability.
D, corrosion resistance, high temperature resistance, low temperature drift
Sputtering thin film pressure transmitter
PPM-241A also measures the signal by measuring the oil pressure to collect the weight, and the digital circuit is used to deal with the signal of the sensor according to the specific requirements of the customer.
1. The characteristics of the product:
A, the signal is big, easy to convert.
B, high precision, good stability.
C, anti shock, impact, overload ability.
D, strong anti-interference ability.
E, corrosion resistance, high temperature resistance, low temperature drift
Resistance strain sensor
(commonly known as patch sensor PPM-242L)
The loader weighing the weight of the goods, the oil pump is connected with the bucket is constantly moving, within the pump oil (medium test) after repeated high pressure, the temperature will rise, PPM-242L sensor in strain selection considering the factors of temperature, high temperature strain gauge, as in the process to take corresponding measures to let the temperature drift as small as possible in the system, < + 0.03%FS, at the time of installation is generally by the pressure pipe installation. In this way, the temperature and impact of the sensor are relieved and the stability of the equipment is increased.
1, the main features of PPM-242L:
A, high precision, long-term stability.
B, good seal, corrosion resistance.
C, low cost, high cost performance.
1, the thread installation should ensure the seal, and the sealant or the raw material should be used in the installation.
2. The wiring is strictly carried out in accordance with the product instructions to prevent the damage caused by misoperation.
3, the multi parameter test should be carried out to different azimuth and angle to ensure that the equipment has the same weighing precision in various states.
4, if the space limit can not be installed normally, we should consider the way of introducing and installing the pressure tube, and then fix it after the debugging is completed.