The structure and working principle Magnetic powder clutch is (input shaft), driven by the active rotor rotor (output shaft), including excitation coil of the magnetic yoke of relative concentric three parts assembly, can form a relative rotation of the whole, in the annular space between the driving rotor and driven rotor cavity (work) filled with high magnetic conductivity alloy magnetic powder. Excitation, and current through the coil, the working cavity of magnetic powder in loose state.In under the action of centrifugal force generated by the active rotor and magnetic powder is evenly in the active rotor on the inner wall of weak interaction between the main rotor, driven, magnetic powder clutch in the separation of state, not the transmission of torque. Excitation coil is energized, the yoke of magnetic flux, the magnetic powder in working cavity along the direction of the magnetic flux linked in chain (form a chain of magnetic powder), magnetic powder clutch is depend on the magnetic powder and magnetic powder, and the working surface between friction and magnetic powder chain between the shear resistance to transfer torque, magnetic powder clutch in the combined state.(see figure 1) Cut off the current, flux disappear, with the disappearance of the exciting current of magnetic powder under the action of gravity, in a loose state again, and under the action of centrifugal force, was in active rotor on the inner wall of magnetic powder clutch and is in a state of separation. The principle of magnetic powder brake and magnetic powder clutch is the same, as long as the magnetic powder clutch driven rotor fixed, magnetic powder brake was created.
features The excitation current and torque is linear relationship As shown in figure 3, transfer torque and excitation current of a linear relationship with basic.As long as you change the size of the excitation current, can control the size of the torque on a wide range.Normally within the scope of 5% to 100% of the rated torque, exciting current and the transmission torque directly proportional basic linear relationship. The stability of sliding structure moment When the excitation current is kept constant, the transmission of torque is not affected by active speed difference between a follower (slip speed), as shown in figure 4.That is to say, there was no difference in the static friction torque and friction torque, thus to achieve stable torque constant.This feature is applied to tension control, the user as long as the excitation current can accurately control the torque, so as to effectively control the tension of coil. Prevent due to slip of fever Usually continuous sliding friction parts will be fever, and even burn out.But this equipment has the complete radiator, long time operation is not too hot, and long service life.
Scope of application: Because the magnetic powder clutch/brake has the above features, has been widely used in papermaking, printing, plastics, rubber, textile, printing and dyeing, wire and cable, metallurgy and other relative coiling processing industry in winding and rolling tension control.The following is a set of relatively complete tension control system diagram.
In addition, magnetic powder clutch can also be used to buffer starting, overload protection, control, etc.;Magnetic powder brake can also be used for mechanical transmission test load, brake, etc.
First, we explain two nouns:
1. The slip speed: magnetic powder clutch as the speed difference between input and output shaft, magnetic powder brake as the input shaft speed;
2. The slip power: magnetic powder clutch/brake on the transmission torque, because there are slip speed and power generation.
Selection of magnetic powder clutch/brake on the required on the basis of the maximum torque and rotational speed.But at the same time to ensure its practical work the slip power of less than the rating, because the slip power is converted into heat cause temperature rise of each part parts.The specific calculation formula is as follows: P = 2 ∏ / 60 * M * n
Type: P - slip power (unit: w)
M - torque (unit: N•m)
N - slip speed (unit: r/min)
F - work tension (unit: N)
V - linear velocity (unit: m/s)
Example: FZ100 / Y double water cooling magnetic powder brake, the slip power is 7000 w, the rated torque of 100 n. M, allowable speed of 1500 r/min.
When it work in rated torque, allowing a maximum speed of: n = 60 x (P)/(2 ∏ (M) = 9.55 x P/M = 9.55 x 7000/100 = 668.8 (r/min)
When its work in the highest slip speed, maximum allowable torque is: M = (60 x P)/(2 ∏ (n) = 9.55 x P/n = 9.55 x 7000/100 = 44.6 (N•m)
Shall not be overloaded, cooling in place
Magnetic powder clutch/brake on the job, the torque, rotational speed, smooth and power shall not exceed the rating.Cooling (natural cooling, forced air cooling and water cooling) should be based on actual work when the maximum slip power.Cooling air filter oil and water.With conditions, can be mounted to the temperature detection, alarm device, to prevent temperature is exorbitant, affect the service life of magnetic powder.The highest temperature (80 ℃)
The use of magnetic powder clutch/brake life lies in the life of the magnetic powder.In general, magnetic powder in the condition of not overloaded, its service life is 4500-7500 hours;But in some condition it can prolong service life many times, such as: reduce the magnetic powder clutch/brake torque, relative sliding speed and slip power to the rating of 50% 70%.That is to say, when the design, allowance enlarge some as much as possible.
About the torque
Magnetic powder clutch/brake factory after use, the magnetic powder in the early stages of using break-in happens, torque will be slightly down, can be adjusted by electric current to compensate.
Install the sample