(1) High mechanical properties. Epoxy resin has strong cohesion and dense molecular structure, so its mechanical properties are higher than general-purpose thermosetting resins such as phenolic resin and unsaturated polyester.
(2) Strong adhesion. The epoxy resin curing system contains extremely active epoxy groups, hydroxyl groups, and polar groups such as ether bonds, amine bonds, and ester bonds, and imparts epoxy cured products to metals, ceramics, glass, concrete, wood, etc. The substrate has excellent adhesion.
(3) The curing shrinkage rate is small. Generally it is 1% to 2%. It is one of the varieties with the lowest cure shrinkage in thermosetting resins (8% to 10% for phenolic resins; 4% to 6% for unsaturated polyester resins; 4% to 8% for silicone resins). The coefficient of linear expansion is also small, generally 6 x 10-5 / °C. Therefore, the volume changes little after curing.
(4) Good processability. When the epoxy resin is cured, substantially no low molecular volatiles are produced, so that it can be formed by low pressure molding or contact compression molding. It can be used together with various curing agents to produce environmentally friendly coatings such as solvent-free, high-solids, powder coatings and water-based coatings.
(5) Excellent electrical insulation. Epoxy resin is one of the best electrical properties of thermosetting resins.
(6) Good stability and excellent chemical resistance. An epoxy resin containing no impurities such as alkali or salt is not easily deteriorated. As long as it is stored properly (sealed, not exposed to moisture, high temperature), its shelf life is 1 year. If it passes the inspection after the expiration, it can still be used. The epoxy cured product has excellent chemical stability. Its resistance to alkali, acid, salt and other media is better than that of unsaturated polyester resins, phenolic resins and other thermosetting resins. Therefore, epoxy resin is widely used as an anti-corrosion primer, and the epoxy resin cured product has a three-dimensional network structure and can be impregnated with oil, etc., and is widely used in oil tanks, oil tankers, and the inner wall lining of an entire fuel tank of an aircraft.
(7) The heat resistance of the epoxy cured product is generally 80 to 100 °C. The heat resistant type of epoxy resin can reach 200 ° C or higher.
small fan
DC Fan is through the input DC power, so that the DC motor rotates to drive the fan impeller rotation, in order to achieve DC to mechanical energy conversion process fan. The biggest feature of Dc Fan is the optional DC motor.
Introduction
At present, DC fans use more DC brushless motors. Brushless DC motors eliminate the need for slip rings and brushes for excitation and greatly simplify the structure. At the same time, it not only improves the processability of the motor, but also greatly enhances the mechanical reliability of the motor operation and increases the service life.
At the same time air gap flux density can be greatly improved, the motor indicator can achieve the best design, the direct effect of the motor is reduced in size and weight. Not only that, but also has very good control performance compared to other motors. This is because: First, the torque constant, moment of inertia ratio, power density and the like of the motor are greatly increased due to the high performance of permanent magnetic materials. Through rational design and can make the moment of inertia, electrical and mechanical time constants and other indicators greatly reduced, as a major indicator of servo control performance has been greatly improved. Second, the design of modern permanent magnetic circuit has been more perfect, coupled with the high coercivity of permanent magnetic materials, and thus permanent magnet motor anti-armature reaction and its anti-demagnetization greatly enhanced the control parameters of the motor with the external Disturbance effect greatly reduced. Thirdly, since the permanent magnet replaces the electrical excitation and the design of the field winding and the field magnetic field is reduced, the parameters of the field flux, the field winding inductance and the field current are reduced, thereby directly reducing the controllable variable or the parameter. Based on the above factors can be said that permanent magnet motor with excellent controllability.
At present, large-capacity fan air flow control has been a lot of frequency control methods, this type of inverter mainly rely on imports, expensive. Currently 1kw below the power level of fans, especially home air conditioners and other fans have permanent magnet brushless DC motor drive, and the use of speed control air volume method. 1 ~ 10kw power range of the huge amount of fan, the basic induction motor drive, and adjust the outlet opening to adjust the amount of wind. For fans in this power range, using permanent magnet brushless DC motor drives to replace the original induction motor drive has great advantages.
DC Fan
Dc Fan,Dc Cooling Fan,Plastic Dc Fan
Shenzhen Fu Sheng Electric Co., LTD. , http://www.fushengfan.com