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Zhang S.,South China University of Technology | Zhang S.,Xiamen Hongfa Electroacoustic Co. | Huang H.,South China University of Technology
Gaofenzi Cailiao Kexue Yu Gongcheng/Polymeric Materials Science and Engineering | Year: 2011

Glass fiber reinforced flame retardant PBT (GFFRPBT) with five times mold-injection was prepared, and the properties and influence factors of GFFRPBT with different mold-injection times including mechanical and thermal were well investigated. The results demonstrate that when GFFRPBT is processed third time, the length of glass fiber and characteristic viscosity of PBT decrease to 590 μm, 0.52, respectively. It also indicates that the trend of the decrease accelerates with more mold-injection times. After second times mold-injection, the notched impact strength, flexural and tensile strength of recycled GFFRPBT (RGFFRPBT-2nd) decrease to 54 J/m, 128 MPa and 96.1 MPa, respectively. Thermal stability, maximal crystallization temperature, melting point and hot deformation temperature of RGFFRPBT-2nd are not significant different from those of GFFRPBT. The results illuminate that mechanical and thermal properties of RGFFRPBT-2nd are suitable to use in the electronic and electric field. With the mold-injection times increase, the properties of RGFFRPBT significantly decrease. Source

Zhai G.,Harbin Institute of Technology | Wang Q.,Xiamen Hongfa Electroacoustic Co. | Yang W.,Harbin Institute of Technology | Liang H.,Harbin Institute of Technology
IEEE Transactions on Magnetics | Year: 2012

The permanent magnet (PM) is the key part of the relay. This paper aims to solve the problem of the uneven magnetization for the PM with nonlinear demagnetization curve after magnetizing and demagnetizing. A method partitioning the PM along the magnetization direction and the vertical direction of magnetization according to the condition of the specific magnetization of the PM was presented. By this method, the demagnetization model of the PM was built, the state of the PM magnetization was simulated under the demagnetizing magnetic intensity, and the recoil line and its initial point of each partition of the PM were obtained. Then the characteristic of the recoil line of each partition was used as its magnetic characteristic for the equivalent model of the PM to calculate the static torque characteristics under the demagnetizing magnetic field. Finally, the static torque characteristics of simulation and experiment were compared and the validity of the equivalent model presented was verified. © 2012 IEEE. Source

Xiamen Hongfa Electroacoustic Co. | Date: 2010-03-09

A connection structure of an armature and a pushing mechanism of a relay has an armature and a pushing block. The head of the armature is T-shaped and connected by a vertical arm and a cross arm. One end of the pushing block has a bar-shaped through hole and a bar-shaped blind hole, disposed alongside and vertical to the motion direction of the pushing block. A through groove to connect the bar-shaped trough hole and the blind hole is disposed at the centre of the bar-shaped through hole and the blind hole. With the through groove, the T-shaped armature head can move along the through groove when the T-shaped armature head is shoved into the bar-shaped through hole. The cross arm of the T-shaped armature head is dropped into the bar-shaped blind hole to cooperate with the bar-shaped blind hole to drive the pushing block when the armature swings.

Tan L.,South China University of Technology | Su Q.,Xiamen Hongfa Electroacoustic Co. | Zhang S.,South China University of Technology | Huang H.,South China University of Technology
RSC Advances | Year: 2015

This study focused on achieving biodegradable thermoplastic polyurethane (TPU) blends with good mechanical properties by the incorporation of starch. Thermoplastic starch (TPS) was developed by plasticizing corn starch in a twin screw. Polyolefin elastomer (POE) was used as the compatibilizer to improve the flexibility of the TPU/TPS system. The miscibility of the blends was investigated by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Mechanical analysis (impact, tensile, and folding endurance tests), dynamic mechanical analysis (DMA), degradation tests and contact angle (CA) tests were employed to study the mechanical properties and hydrophilic sensitivity of the TPU/TPS blends. The results showed that POE improved the miscibility of the blends by enhancing the interfacial effects of the TPU/TPS blend, decreasing the interfacial tension between TPS and TPU, as well as increasing the inter-hydrogen bonds between TPU and TPS. The hydrophilic qualities of the TPU blends, such as water adsorption and CA, increased with increasing TPS content, resulting in improved biodegradation ability. TPU/TPS (20 wt%)/POE (10 wt%) endowed the blends with good folding endurance (>30.0 × 103), notched impact strength (no break), elongation at break (>800%) and a 6.2% biodegradation rate after 7 weeks. The improved properties of TPU/TPS showed that these blends have high potential for use in environmentally friendly materials. © 2015 The Royal Society of Chemistry. Source

Chen Z.,Electrical Contacts Plus LLC | Jiang C.,Xiamen Hongfa Electroacoustic Co. | Lu N.,Xiamen Hongfa Electroacoustic Co.
Proceedings of the 5th International Conference on Reliability of Electrical Products and Electrical Contacts, ICREPEC 2014 | Year: 2014

Contact resistance failure is one of the major concerns in relay assembly line. This failure not only increases the cost of production, but also can lead to potential problem in early applications. In this paper, the effect of copper particles on contact resistance has been studied and the failure mechanism and root cause have been defined. It has been found that the copper particles on contact surface can cause the high contact resistance by two ways: one is forming copper oxides due to high temperature during relay sealing process and the other is accelerating mechanical wear and wear debris accumulation when contacts wipe during mechanical vibration process. Source

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