Principle and application of magnetic powder brake
Magnetic powder brake is commonly known as magnetic powder motor, magnetic powder brake, magnetic powder tensioner, etc.
The magnetic powder brake MAGPOWR is based on the electromagnetic principle and uses magnetic powder to transmit torque. It has the characteristics of a substantially linear relationship between the exciting current and the transmission torque. It can transmit a certain torque under the condition that has nothing to do with the slip, and has the advantages of fast response speed, simple structure, no pollution, no noise, no shock vibration and energy saving. It is a multi-purpose, high-performance automatic control element. Has been widely used in papermaking, printing, plastics, rubber, textiles, printing and dyeing, wire and cable, metallurgy, tablet presses and other related winding processing industry unwinding and winding tension control. Magnetic powder brakes are also often used for dynamometer loading and braking of transmission machinery.
1: Magnetic powder brake is a new type of transmission element that uses magnetic powder as a medium and forms a magnetic powder chain to transmit torque when energized. It is mainly composed of an inner rotor, an outer rotor, an exciting coil and magnetic powder.
2: When the coil is not energized, the driving rotor rotates. Due to the centrifugal force, the magnetic powder is thrown on the inner wall of the driving rotor. There is no contact between the magnetic powder and the driven rotor, and the driving rotor is idling.
3: An electromagnetic field is generated after the DC power supply is connected. The magnetic powder of the working medium forms a magnetic powder chain under the action of the magnetic field lines. The inner rotor and the outer rotor are connected to achieve the purpose of transmitting and braking torque.
1. Buffer start and stop: use the smooth characteristics and constant torque characteristics when connected to achieve buffer start and stop.
2.For continuous sliding and tension control
3.For torque limiter
4.For high-speed response
5.For power absorption
6. For positioning stop
7, characteristics of simulated load
1. Can control a wide range easily.
2, can achieve continuous sliding operation.
3. A stable torque can be obtained.
4. No tweet sound. The slipping phenomenon of the action surface occurs in the friction mode, but it does not appear here, and no connection sound is emitted, so the operation is quite quiet.
5. The heat capacity is very large. Due to the use of magnetic powder with excellent heat resistance and the ideal cooling method, it can be used safely even in the severe continuous sliding operation.
6, can achieve smooth continuous and driving state. Since the static friction coefficient and the dynamic friction coefficient are almost the same, vibration will not occur when fully connected, and it can respond to the load acceleration and deceleration.
Explanation The magnetic powder brake is a combination of a transmission unit (input shaft) and a driven unit (output shaft). The space between the two groups of cells is filled with granular magnetic powder (the rest volume is about 40 microns). When the magnetic coil is not conductive, the torque will not be transmitted from the transmission shaft to the driven shaft. However, if the coil is electromagnetically energized, the magnetic powder will be attracted by the magnetic force to cause hardening, and the torque will be transmitted between successive slips . * Magnetic powder brake is an automatic control element with superior performance. It uses magnetic powder as the working medium and excitation current as the control means to achieve the purpose of controlling braking or transmitting torque. Its output torque has a good linear relationship with the excitation powder current and has nothing to do with the speed or slip, and has the advantages of fast response speed and simple structure. Because of the above characteristics, the magnetic powder brake has been widely used in papermaking, printing, plastic Unwinding and rewinding tension control in rubber, textile, printing and dyeing, wire and cable, metallurgy and other related coil processing industries. In addition, the magnetic powder clutch can also be used for buffer starting, overload protection, speed regulation, etc. Magnetic powder brakes are also often used for dynamometer loading and braking of transmission machinery.
The selection of the magnetic powder brake is generally based on the required maximum torque transmission. At the same time, pay attention to ensure that the actual slip power is smaller than the allowable slip power of the magnetic powder clutch and brake. The calculation formula is as follows: Actual slip power P = 2 × 3.14 × M × n / 60 = F • V (unit: W) where: M ----- actual working torque (N • m) F --- -Tension (N) n ----- Slip speed (r / min) V ----- Linear speed (m / s) ● Without speed change mechanism, the maximum tension required for winding the material The product of the maximum winding radius should be less than the rated torque of the magnetic powder brake. In addition, the choice of magnetic powder clutch is also related to its position: under the premise of matching slip power, if the magnetic powder clutch is placed at a high speed, a smaller size clutch can be selected, and its volume and cost will be reduced accordingly. When the small-size magnetic powder clutch cannot be matched, but a larger magnetic powder clutch is needed, it should be placed in the middle or rear of the transmission mechanism to increase the working torque and reduce the slip speed. ● When the magnetic powder clutch and magnetic powder brake have a certain heat dissipation condition, their slip power is a certain value, so their actual working torque and rotational speed can compensate each other. That is, when the slip speed increases, the allowable torque will decrease accordingly, but the highest The speed must not be higher than its permitted speed. Example: FZ100 magnetic powder brake, its rated torque M = 100N.m, slip power P = 7KW, then the rated speed n = 9550 * P / M = 9550 * 7/100 = 668.5r / min if the actual slip speed n = 1500r / min (where 9550 is a constant coefficient), the allowable torque should be M = 9550 * P / n = 9550 * 7/1500 = 44.6Nm (where: 9550 is a constant coefficient)
Functional characteristics (1) High-precision torque control The control range of the torque is very wide, and the control accuracy is high. It conveys the torque and the exciting current into the correct ratio, which can achieve high-precision control.
(2) Superior durability and long life The super alloy magnetic powder with heat resistance, wear resistance, oxidation resistance and corrosion resistance is used for long life.
(3) Stable constant torque characteristics of magnetic powder The magnetic characteristics of magnetic powder are good, and the binding force between the particles is stable, the sliding torque is very stable, and it has no relationship with the relative number of revolutions. It can maintain a constant torque for a long time.
(4) The continuous sliding operation uses a cooling structure with excellent heat dissipation and uniform thermal deformation, coupled with the high heat resistance of magnetic powder, allowing large connection and braking power and sliding power. It can perform smooth sliding operation without causing vibration.
(5) The connection is smooth, and the impact during the non-impact connection is extremely small, enabling smooth start and stop without impact. And the resistance torque is extremely small, which will not cause useless heat generation.
(6) Suitable for high-frequency operation with agile and fast response and special heat dissipation structure, suitable for high-frequency operation.
(7) Lightweight, maintenance-free, long life, simple and lightweight, using high temperature resistant coils and special grease bearings, and applying abrasion-resistant special treatment for abrasion-prone armatures to extend service life.