The hydraulic system will have different failure phenomena in different operation stages. Dalan Hydraulics tells you that the main performances of the hydraulic system will have different failure phenomena in different stages of operation in the following stages. Dalan Hydraulics tells you that the main performances are as follows. Stages:
At present, the five most commonly used Thermosetting Plastics in various fields are PU, epoxy resin (EP), silicone, unsaturated polyester (UP) and phenolic resin (PF).
Thermosetting Plastic has the following advantages:
Thermosetting plastic has a large rigidity and is extremely elastic and plastic deformation.The temperature has little influence on stiffness, and under the same load and temperature, the creep variable is much smaller than thermoplastic.Good heat resistance;The plastic parts are quite stable when heated.The size of the plastic parts is good. Thermosetting plastic is less affected by temperature and humidity, and Thermosetting plastic can be reduced after forming, making Thermosetting plastic easy to make plastic parts with high precision than thermoplastic ruler.Excellent electrical performance.Resistance to arc and voltage, etc.Good corrosion resistance, weak acid, weak base and organic solvents;Good processability, can be processed by various molding methods and other advantages.
Most thermosetting plastics have the following characteristics:
(1) excellent chemical resistance.
(2) it is usually brittle hard plastic, which can be filled with various fillers to form composite materials.
(3) compared with thermoplastic resin, the molding cycle is longer.
(4) all kinds of modification can be carried out, depending on the combination of resin, crosslinking agent, additive, etc., which can form composite materials with different properties.
(5) good heat resistance, the use of high temperature, Tg of thermosetting polyimide (PI) is about 350 ℃.
(6) can be used as raw materials to meet the application of various fields.Only 5% is used as injection molding material.
(7) the waste is generally used as filler after pulverization, which is difficult to recycle and pollutes the environment.
Due to the high heat resistance of thermosetting plastic, good dimensional stability, good line performance, anti-aging properties are better than thermoplastic plastic and low price, so it is widely used.The disadvantage is that the mechanical properties are poor and need to be enhanced.
It is mainly composed of thermosetting resins, which are involved in various necessary additives to form the plastic of the products.In the process of manufacturing or forming, the liquid will be liquid, which will not melt after curing or melt or soften again.Common thermosetting plastics include phenolic plastic, epoxy plastic, amino plastic, unsaturated polyester, alkyd plastics, etc.Thermosetting plastic and thermoplastic plastics constitute two major components of synthetic plastic.
Thermosetting plastic heating for the first time can soften the flow, heated to a certain temperature, react a crosslinking reaction and curing hardens, this change is irreversible, since then, heating again, already no longer soft flow.It is the use of this characteristic to make the molding process, using the plasticization flow of the initial heating, filling the cavity under pressure, and solidifying to become the product that determines the shape and size.
Thermosetting plastic is distinguished by a chemical reaction that is hardened by heating, pressing or adding the hardener at a definite temperature.After hardening, plastic chemical structure changes, the texture is hard, dissolves in the solvent, heating also no longer softens, if the temperature is too high then decompose.In thermoplastic plastic, the chains of resin molecules are linear or branched, and there is not any chemical bond between the molecular chains, which soften the flow when heated.The process of cooling and hardening is a physical change.
Formaldehyde cross linked plastic includes phenolic plastic, amino plastic (such as urea-formaldehyde - melamine - formaldehyde, etc.).Other cross linked types of plastic include unsaturated polyester, epoxy resin, prevalence, diallyl ester resin, etc.
The commonly used thermosetting plastics are phenolic resin, urea-formaldehyde resin, melamine resin, unsaturated polyester resin, epoxy resin, silicone resin, polyurethane, etc.
Production:Phenolic resin PF (Bakelite sheet)
Phenolic resin is a part of the longest plastic varieties in history, commonly known as bakelite or electric wood, and the appearance is yellowish or black, which is the typical representative of thermosetting plastic.Bakelite sheet molding often use a variety of filling materials, according to different filling materials used, the product performance is also different, Bakelite sheet as molding material, mainly used in the field of need heat resistance, but also as a bonding agent used in plywood, grinding wheel and the brake pads.
1, no-load debugging stage
The hydraulic system at this stage has the highest failure rate and is more complicated. It is characterized by the problems of design, manufacture, installation and management. In addition to mechanical and electrical problems, common hydraulic system failures are as follows:
1 Component connection leaks.
2 The valve core is stuck or the movement is not flexible, causing the actuator to malfunction.
3 The damper hole is blocked, causing the system pressure to be unstable or the pressure to be adjusted.
4 valve components are missing springs or seals, or the pipes are connected incorrectly to make the operation disorder.
5 improper design, improper selection, so that the system is hot, or the movement is not coordinated.
6 hydraulic parts processing quality is poor, or the installation quality is poor, resulting in valve movement is not flexible.
7 oil block block channel design error.
8 Control system components are not working properly.
2, with the trial run phase
After the no-load debugging is completed, many problems have been solved, and after a period of no-load running, the system oil is relatively clean, the valve core is stuck, the movement is not flexible, and the damping hole is blocked. The problem is mainly Expressed in the following aspects:
1 Position accuracy and synchronization accuracy are not up to standard.
2 system back pressure is too large, design pressure can not drive the load.
3 improper design choices cause the system to heat up.
4 The pressure component setting value is unreasonable.
5 The oil filter is clogged.
3. Stable operation stage
After a period of trial operation, the hydraulic system will have a stable operation period, and there will be no major problems. The main problems are mainly in the following aspects:
1 Leakage caused by seal aging, damage and loose bolts.
2 The filter is clogged, the oil problem, etc. cause a malfunction.
3 Incorrect operation and maintenance caused failure.
4, the component failure rate is high
After the running time of the hydraulic system reaches the life of the component, the components such as the pump and the motor begin to fail one after another. The main problems are as follows:
1 The component wear is seriously caused to increase the internal leakage of the system.
2 The pressure element spring becomes soft and the pressure is abnormal.
3 The pump is seriously worn, resulting in insufficient oil supply and pressure.
4 cylinder seal is seriously damaged.
----- Editor-in-Chief: Dalan Oil Pump Motor 02-Procurement Consultant
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