turn off. The hydraulic cylinder ceramic coating displacement measurement Introduction The surface of the piston rod of the ceramic coating hydraulic cylinder is sprayed with cermet coating, which makes the piston rod surface have high chemical stability, high hardness, high rigidity and low friction coefficient. It is suitable for working environment. , used under strong corrosive or seawater conditions.
At present, hydraulic hoist hydraulic cylinders used in many foreign hydropower stations and marine development projects use ceramic coatings.
Some hydropower projects under construction or preparation in China, large-scale hydraulic projects such as the Yangtze River Three Gorges Project, small and medium-sized hydraulic hoist cylinders such as the Fujian Cotton Beach Hydropower Station, require the use of ceramic-coated hydraulic cylinders.
It is expected that ceramic coated hydraulic cylinders will be widely used in China's hydropower projects.
At the annual International Power and Control Technology Exhibition held in Shanghai, the German company Honggel exhibited a sample of ceramic-coated hydraulic cylinder piston rods, distributed technical materials, sent experts to consult on site, and welcomed users to visit them. The ceramic coating plant indicates that its ceramic coating technology has matured.
We have carried out translation studies on the technical data of Honggel Company. Taking it as an example, combined with the development results of China's ceramic spraying technology, the technical characteristics of the processing technology of the ceramic coated piston rod and the working procedure and performance of the displacement measuring system are as follows: analysis.
Spraying process analysis German Hunger's ceramic coated piston rod processing technology is divided into five parts. Figure processing substrate spraying nickel-chromium bonding layer Buchuan spraying cermet layer coating sealing agent grinding grinding grinding ceramic coating construction Process Flow Diagram The substrate used for the ceramic coating can be almost any solid, such as metal plastic wood.
The base used as the piston rod is mostly steel.
According to the technical conditions used by the hydraulic cylinder, the piston rod is selected and processed.
The piston rod can be either a bar or a hollow profile.
According to the needs of the displacement measuring system, the outer surface of the piston rod can also process a plurality of rectangular grooves of equal width.
At present, the maximum length of the ceramic coated hydraulic cylinder manufactured by Honggeer is the maximum diameter of the piston rod. After the maximum weight of the piston rod is processed, the nickel-chromium bonding layer is first sprayed.
Tests have shown that the corrosion resistance and surface strengthening method of the base metal surface material will have a great influence on the corrosion resistance of the ceramic Xu layer piston rod.
A nickel-chromium bonding layer is sprayed on the surface of the substrate, and the purpose is to add a corrosion-resistant protective layer to the outside of the substrate.
Honggel sprays a nickel-chromium bond layer using a high-speed flame spray process.
If grooves are machined on the surface of the substrate for the purpose of the displacement measuring system, the nickel-chromium layer is also completely filled after spraying.
On the basis of the nickel-chromium bonding layer, the cermet layer can be sprayed.
Honggel Company adopts plasma spraying technology. The basic principle is as shown in the figure. The powder sprayed in the basic schematic diagram of the plasma jet is a mixture of several metal oxides.
According to the different requirements of the piston rod surface corrosion resistance, high hardness, high temperature resistance, wear resistance and low friction coefficient, the composition of the metal oxide powder sprayed by Honggeer is also different.
A typical composition is a mixture of chromium oxide and oxidized chin, a mixture of alumina and oxidized calcium oxidized oxide, or a mixture of alumina and oxidized oxime, or the like.
The entire injection process is all done by computer control.
The high temperature of the plasma flame sprays the metal oxide powder onto the substrate at a very high rate, so that the powder is melted and adhered to the surface of the activated substrate with high kinetic energy.
The mating rotation of the substrate and the effective cooling system not only effectively control the temperature of the substrate below, but also the microstructure and properties of the substrate do not change, the workpiece does not deform, and the thickness error of the ceramic coating is controlled below, which not only ensures the ceramic. The necessary thickness of the coating also facilitates the future grinding and grinding processes.
Through testing, the total thickness of the sprayed ceramic coating of Honggeer can reach the surface hardness between the two. See the hydropneumatic and sealing years. The finishing process is the gap between the film and the layer of the film. Quasi-arch-nickel-bonded layer èƒ center line diagram ceramic coating schematic After spraying the ceramic coating, there is a necessary post-processing process to seal the hole.
Since the ceramic coating is composed of a myriad of particles, although the particles are very small, there are still some pores, and it is possible to form an infiltration from the surface of the ceramic layer to the substrate, thereby causing corrosion of the surface of the substrate, so the ceramic coating must be applied. Sealing.
Honggel Company adopts resin sealing agent, which can be painted at room temperature, evenly coated on ceramic coating, and naturally dried and cured at room temperature.
It is characterized by strong adhesion, easy penetration, good chemical stability, strong corrosion resistance and impact resistance, and is easy to construct.
After the sealing agent is completely cured, in order to improve the surface roughness of the ceramic coated piston rod, grinding and polishing are also performed to reduce the friction of the piston rod and improve the service life of the sealing member.
Hunger's grinding and lapping is done on a special machine tool using a diamond grinder to control the surface roughness of the ceramic coated piston rod between the two.
Characteristics of ceramic coated hydraulic cylinders Honggel's ceramic coated hydraulic cylinders are tested by German and standard, hourly brine test, for dilute acid such as sulfuric acid formic acid, sodium hydroxide and other alkalis, sorghum, pure water, brine, industrial gas, etc. Has a strong resistance to corrosion.
Moreover, due to its extremely low friction coefficient and ultra-fine processing, the life of the seal is greatly extended and the working life of the hydraulic cylinder is prolonged.
Another feature of ceramic-coated hydraulic cylinders is that they can be repaired at the job site without disassembly.
General scratches and scratches A small area of ​​bumps, etc., as long as the repair agent is applied to the surface, after the natural drying and curing, the repair work is completed, especially suitable for large hydraulic cylinders that are not easy to disassemble.
Coating hydraulic cylinder displacement measuring system Hunger ceramic coating hydraulic cylinder is equipped with incremental displacement measuring system. When the piston rod is running, the position of the piston rod can be accurately measured to drive the integrated positioning system and the synchronous system.
This allows the piston rod to be accurately positioned and two or more hydraulic cylinders to work simultaneously, which is extremely important for hydropower projects where two or more hydraulic cylinders control the same gate.
The working procedure of the incremental displacement measuring system is shown in the figure.
Inductive body electromagnetic sensor Bu measurement display and output mechanism Chuan positioning proportional servo mechanism Bu actuator mechanism coating hydraulic cylinder displacement measuring system sensing body using the piston rod itself.
Generally, each of the spacers on the surface of the piston rod has a rectangular groove, and the groove is filled after being sprayed with the ceramic coating.
Due to the difference in electromagnetic induction between the interacting materials, the grooves can accurately reflect the electromagnetic induction to the electromagnetic sensor.
The electromagnetic sensor is built-in and installed in the end cap of the hydraulic cylinder, which not only avoids external mechanical shock, but also prevents the influence of dust and debris.
The Hunger company uses a Hall effect sensor and uses two sensors with a phase angle difference of 90.
The rectangular wave electric signal output by the sensor is proportional to the stroke of the piston. With the incremental principle, the electric signal is amplified, divided and passed through the phase discriminator, which can resolve the groove width of the piston rod four times, so as to be accurate over the entire stroke range. The positional velocity and acceleration of the piston are measured and reflected to the position display and output mechanism as an integrated signal.
The position display and output mechanism provides a remote display of the hydraulic cylinder piston position, provides the analog output signal of the pilot, and transmits the signal to the computer, which can be used in the closed-loop control of the programmable hydraulic cylinder displacement measurement system to make two or more The hydraulic cylinders operate in precise position.
Hongger's displacement measurement system, in addition to the main power supply, is equipped with a backup power supply, even in the case of sudden power failure, the signal will not be lost, which provides a guarantee for the reliable operation of the system.
After testing, Honggel's displacement measuring system is used on hydraulic cylinders whose stroke does not exceed 20 rods. The resolution is generally up to the special requirements, and the soil can reach the temperature range at the highest speed. When it works, it works fine.
Honggele can also provide displacement measurement systems that are used above the above temperature range or for higher operating speeds to meet the different needs of users.
Conclusion Ceramic-coated hydraulic cylinders are a technology in the hydraulic industry. Their application in China is just getting started. In addition to hydropower projects, in other fields, such as chemical petroleum ship metallurgy machinery, there are also broad application prospects, with ceramic spraying. With the development of technology and the reduction of cost, ceramic coated hydraulic cylinders will surely be accepted by more users.
Zhang Yu, a female product author of the German Hongger company, graduated from the Department of Electrical Automation of Tianjin Institute of Technology. He graduated from the English Department of Tianjin Normal University, double bachelor, engineer, and crafts department of Yujin Hydraulic Machinery Group Co., Ltd. , Tianjin Nankai Sanwei Road No., received date one
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