Views: 11 Author: Site Editor Publish Time: 2021-12-23 Origin: Site
Piston type water meter detection device
Liquid flow standard device is widely used in liquid flow meter experiment and verification device, especially for flowmeter production enterprises, there are a lot of instrument verification work and experimental work of product development, a set of efficient and reliable liquid flow standard device is of great significance to their production activities. In industrial application, flow standard device should not only have enough accuracy and reliability, but also have relatively high verification efficiency. Also consider the construction cost of the device, the operating cost, the technical requirements of operators and other factors. Traditional liquid flow standard device is based on quality standard, the more volume of standard device, to generate pump provides traffic flow source, but the flow is fluctuating, flow stability, flow point adjustment is not precise, but with the rapid development of the flow measurement and testing technology, these devices are not well meet the requirements. For liquid flow meter calibration, calibration, inspection, and the growing trend of new type flowmeter production, were designed and manufactured by our company with water as the medium of active piston liquid flow standard device, the standard device design is unique, its basic principle is to a certain time interval piston discharge volume flow of the fluid and the volume flow of test meter. The volume of fluid expelled by the piston is obtained by multiplying the cross-sectional area of the piston cylinder with the displacement of the piston. Driven by servo motor, the disturbance to liquid flow is reduced, which has many advantages, such as stability, reliability, good repeatability, high degree of automation and simple operation. It avoids the start-stop effect or commutator effect point existing in the traditional liquid flow standard device, and is conducive to improving the measurement uncertainty level. The device also has the characteristics of self-contained, compact structure, high efficiency and energy saving, no need to build a pool, no need to put forward special structural requirements of the building, very suitable for the production testing and product development testing of small flow meters.
Two, technical indicators
1, device uncertainty: ≤0.2%(K =2) flow stability ≤0.2%;
2, the working pressure of the device: 0-1mpa;
3, the operating temperature of the device: 5-85 ℃;
4, the number of inspection meter: ultrasonic or ordinary water meter DN15:10 DN20:10 DN25:8, the
He meter according to the length of the pipe to calculate the number of clamping;
5, communication interface: M-BUS, RS485;
6, control system: Siemens PLC, industrial touch screen;
7, verification process is automated, with visual interface control, automatic data storage, report generation
Into equal functions.
Iii. Device composition
1. Composition of piston
The active piston liquid flow standard device is shown in Figure 1, which is mainly composed of a frame, piston rod, piston cylinder, motor, ball screw, supporting optical shaft, sensor, protective shell, etc. The piston rod is in close contact with the piston cylinder through the Y-shaped sealing ring, and the three together form a sealed cavity. Movement of the piston rod by servo motor, coupling, ball screw, supporting axis, such as common implementation, the piston rod connected to the ball screw through the screw nut, the direction of motion controlled by servo motor and ball screw, piston cylinder outlet equipped with suction drainage pneumatic valves, pneumatic valves and suction pneumatic valve connection water tank, drainage inspection table pneumatic valve connection line, High precision temperature and pressure sensors are mounted on the piston cylinder.
2. Control system hardware features
The control system is mainly composed of industrial computer, PLC control system, servo motor, grating ruler, various temperature and pressure sensors, pneumatic ball valve, platform software and so on. Industrial computer has strong anti-interference, which makes the verification process more stable and reliable. PLC and servo motor adopt international famous brand with high precision and high reliability. Control and data processing software are written in accordance with relevant national verification regulations.
(1) grating ruler
The standard cumulative flow of an active piston fluid flow standard device is the product of the piston's internal cross-sectional area and piston displacement within a time period. Therefore, accurate measurement of piston displacement is one of the key factors to reduce the uncertainty of the device. In order to improve the accuracy of displacement measurement, grating ruler is used to measure the displacement of piston. The output signal of the grating ruler is AB orthogonal signal, which is 4 times higher than the original accuracy.
(2) Servo motor
The servo system drive components for panasonic servo motor, servo motor is the voltage signal into torque and speed to drive the control object, change the voltage signal can change the servo motor speed and steering. Servo built-in 23 encoder, control precision is higher, servo system according to the instantaneous flow and check quantitative signal sent by the host computer, accurate push piston displacement, servo motor has a large starting torque, a wide range of operation, no rotation phenomenon, high positioning accuracy, widely used in a variety of automatic control system.
The main sensor temperature sensor and pressure sensor, located in the piston cylinder outlet, respectively used to measure the temperature and pressure of the liquid, will be timely information to THE PLC and software system. Sensor is an important component to collect temperature, pressure, humidity and other analog quantities. Its accuracy and performance will directly affect the accuracy of the measurement results of the device. Therefore, it is necessary to integrate various factors and select the sensor products with the highest cost performance. In this device, the temperature sensor temperature measurement range is (0 ~ 100)ºC, accuracy grade is not less than A; Pressure sensor pressure measurement range of (0 ~ 1.6)MPa, accuracy grade is not less than 0.5%.
(4)PLC control system
The PLC control system of the device adopts Siemens S7200smart system, adopts ladder diagram programming language, and mounts analog input and output module to collect and control temperature and pressure signals. PLC is essentially a kind of industrial control computer, the use of programmable memory storage logic operations, sequential operations and other instructions, and through the digital amount and analog amount of input and output, control machinery or production process, PLC and industrial process interface connected with the general computer has no advantage, And PLC itself has a better programming language suitable for control requirements. The device is made according to CE safety standard, with many protection and sound and light alarm, such as low pressure alarm, low water tank level alarm, clamping device is not in place alarm, piston overtemperature alarm, piston overpressure alarm, piston limit alarm, etc.
3. Check the table pipeline
The meter pipeline consists of the meter clamping device, pipe, on/off valve, water tank and so on. The meter clamping device is also called the meter clamping device, which can adjust the spacing according to the length of the meter, and can clamp all kinds of meters to be inspected freely. This scheme table adopts outer cylinder clamping mechanism, effective to prevent the use for a long time and the air leakage phenomenon caused by the damage of seal ring, the test pipe set satisfies the requirement of the clip of test table to pack, general provisions of straight pipe upstream of not less than 10 times checked table diameter, downstream straight pipe not less than five times the inspection table size, The clamping table of the device uses three optical axis as the anchor point, the optical axis is installed on the stainless steel fixed plate for wire cutting production, the coaxiality is very good, the front and back straight pipe section adopts POM material thermal expansion and cold contraction coefficient is very small, the slider uses number
Control machining center one processing. Pneumatic clamp device is also installed on the optical shaft, the use of external cylinder piston propulsion clamping, to avoid the possibility of air leakage. All moving parts are mounted on optical axis to ensure coaxiality.
Iv. Overall software scheme
The main task of the verification system is to complete man-machine interactive dialogue, to achieve the temperature, pressure and other operating parameters of the circuit detection, parameter setting and modification, data analysis and processing and other functions, mainly composed of system management, parameter setting, verification interface, data query and other modules. The system can customize the communication protocol according to customer needs to copy the table data, the system is prepared according to the national standards and metrological verification regulations, and the verification data stored in the database, and print the verification report.