The screw driver is a common tool used to turn the screw to make it in place. It usually has a thin wedge head, which can be inserted into the slot or notch of the screw head. electric screwdrivers,best screwdrivers,felo screwdrivers Shangqiu Zhengtu Hardware Technology Co,.Ltd , https://www.zlztlighter.com
There are mainly one character (minus sign) and cross (plus sign). There are also common hexagon screw drivers, including two kinds of hexagon and hexagon. Each screw driver has different specifications and can be customized.
According to different head types, screwdrivers can be divided into one character, cross, meter character, star (computer), square head, hexagon head, Y-shaped head and so on. One character and cross are the most commonly used in our life, such as installation and maintenance. It can be said that as long as there are screws, screwdrivers will be used.
Hexagonal head is not used much, commonly used in the hexagonal wrench, such as some machines a lot of screws are with hexagonal hole, convenient for multi angle force. We don't see many big ones. Small ones are often used to repair mobile phones, hard disks, notebooks and so on. We call small screwdrivers clock batch. We often use star T6, T8, cross pH0, ph00 and so on.
Stainless steel gear pump structural features and maintenance: one. Sliding bearing stainless steel gear pump sliding bearing materials impregnated graphite, filled with PTFE, engineering ceramics. As the engineering ceramics have good heat resistance, corrosion resistance, abrasion resistance, so the stainless steel gear pump bearing more use of engineering ceramics. As the engineering ceramics are very brittle and the expansion coefficient is small, so the bearing clearance must not be too small, in order to avoid the occurrence of axial accidents. As the stainless steel gear pump to the transmission of the sliding bearing lubrication, it should be based on different media and the use of conditions, the use of different materials made of bearings. two. Quarantine three. Cooling lubricant flow control Stainless steel gear pump operation, you must use a small amount of liquid on the inner rotor and the isolation sleeve between the annular region and the sliding friction bearing pair was washed and cooled. Coolant flow is typically 2% to 3% of the pump design flow, and the annulus area between the inner magnet rotor and the isolation sleeve generates high heat due to eddy currents. When the cooling fluid is not enough or flushing hole poor, blocked, it will lead to the medium temperature is higher than the permanent magnet operating temperature, the magnetic rotor gradually lost magnetism, the magnetic actuator failure. When the medium is water or water-based liquid, the annulus area can be maintained at 3-5 ℃. When the medium is hydrocarbon or oil, the annulus area can be maintained at 5-8 ℃. four. Permanent magnets Permanent magnet made of rare earth permanent magnet has a wide range of operating temperature (-45-400 ℃), high coercive force and good anisotropy in the direction of magnetic field, and will not demagnetize when the same pole is close Phenomenon, is a good source of magnetic field. Fives. Protection When the driven parts of the magnetic actuator operate under overload or the rotor is stuck, the main and driven parts of the magnetic actuator will automatically slide off to protect the pump. In this case, the permanent magnet on the magnetic actuator will generate eddy loss and magnetic loss under the action of the alternating magnetic field of the active rotor, causing the temperature of the permanent magnet to rise and the magnetic actuator to slip off. With a metal isolator, the isolator is in a sinusoidal alternating magnetic field that induces an eddy current and converts it into heat at a cross-section perpendicular to the line of magnetic force. The eddy current is given by: where Pe-eddy current; K-constant; n-pump rated speed; T-magnetic drive torque; F- pressure inside the spacer; D- spacer inner diameter; resistivity of a material; Tensile strength. When the pump is designed, n, T is given conditions, to reduce the eddy current only from F, D and other considerations. Selection of high resistivity, high strength non-metallic materials made isolation sleeve, the effect of reducing eddy current is very obvious.