Centrifuge is a sample analysis separation instrument integrating mechanical, electronic, refrigeration, vacuum, material other technologies, The medical instruments that separate, concentrate purify substances with different sedimentation coefficients through the centrifugal force field generated by high-speed rotation are widely used in biomedicine, petrochemical industry, agriculture, food hygiene other fields. It uses the difference of sedimentation speed of different substances in the centrifugal force field to realize the analysis separation of samples.
Centrifuges can be divided into three types, i.e. low speed, high speed over speed according to the rotating speed. There are two types: table type vertical type. The high speed of the low-speed centrifuge is generally no more than 6000 rpm, which is mainly used for blood cell preparation, protein enzyme precipitation separation. Because the centrifugal force field cannot be generated sufficiently, the low-speed centrifuge cannot separate ultra-small particles (such as viruses, DNA molecules) macromolecules, carry out density gradient centrifugation; The rotating speed of high-speed centrifuge is 12000-28000 rpm, which can separate viruses, bacteria, nuclei, cell membranes, mitochondria, etc. the rotating speed of DNA preparation ultracentrifuge is more than 50000 rpm. With optical instruments, it can be used for molecular weight determination, protein structure aggregation state analysis, compound purity test, etc.
In recent years, with the rapid development of microelectronic technology mechanical industry, the performance reliability of centrifuges have been greatly improved. In this paper, some recent progress of horizontal screw centrifuges is introduced.
Near first drive technology reduces noise vibration
In the past, centrifuges were usually driven by T / C motors, some were driven by high-pressure air flow. Because IX: the carbon brush commutator of the motor are important factors that produce spark interference, noise affect the life of the motor, in recent years, more more frequency conversion motors brushless DC motors are used in centrifuges. The driving mode of the variable frequency motor only saves the work of replacing the carbon brush avoids the pollution of carbon dust, but also the frequency control system is easier to realize the regulation of the speed under the control of the microcomputer, so as to optimize the braking acceleration time. Even when the speed reaches a very high level, the noise vibration can be reduced to a low level. In addition, the frequency conversion drive mode can save electric energy. Position sensor single-chip microprocessor is used to start control the motor of non dramatic DC motor. Common IX: the wear resistance of motor brush has also been greatly improved, some brushes can reach 4000 hours.
Some centrifuges are designed with friction reducing parts stabilizer sleeve in the transmission system, electric quick brake, so that the acceleration of the centrifuges can be increased too much when the speed is raised lowered, the system resonance caused by the critical speed of the rotor can be reduced to the low vibration base suspension bracket of the mining motor, elastic coupling sound wave suppression system to reduce the noise The environment is more peaceful comfortable.