What Should The Magnetic Powder Brake Pay Attention To During Operation?

What are the reasons when the rotor is suddenly stuck during the operation of the magnetic powder brake?

According to the experimental test, showed that the main cause was the gap between the work, which caused the interference. The specific solution was to sand the working surface and replace it with new powder.

I. General matters

(1) Please pay attention to the input and output of the product

Please use the high-speed rotating end as the input end of the magnetic powder clutch for standard installation and use. For continuous idling, the reverse installation of input and output is not good for torque characteristics and magnetic powder life. This method is not recommended. In principle, the clutch and brake are used on the horizontal axis and cannot be used upright. The following usage methods may cause the product to work abnormally.

(a) when used at an angle;

(b) during the overall revolution;

(c) other special occasions such as low temperature;

(2) Installation of pulleys, couplings and shafts

When installing pulleys, couplings and shafts on the product, please pay attention to the fit clearance, and do not apply excessive external force to the product during installation. When the product is exposed to external forces, the internal bearings of the product may be damaged, or damaged in advance.

(3) Please pay attention to the moisture resistance of the product

When the magnetic powder is wet, it may cause unstable performance, so please be careful not to allow water vapor and oil to penetrate into the product. Especially when the product is installed near the gear box, the oil in the gear box will penetrate into the product through the shaft. Be sure to use a sealing ring to completely seal it. In addition, this product is not a sealed structure, so do not use it directly in an environment with oil mist, oil and water.

(4) Please pay attention to the surface temperature of the product

Continuous operation will cause the highest surface temperature. When the temperature exceeds the limit value, the durability of the product will be significantly reduced.

Clutch and brake surface temperature limit values (stator outer periphery) ambient temperature and cooling water temperature are based on 30 ° C. The extreme temperature is used as a reference scale, and it must be used within the allowable continuous slip power.

Relationship between rated torque and rated current

(1) At the time of shipment (test run), when the rated current is applied, the generated torque greatly exceeds the rated torque. This is to consider that the magnetic powder will deteriorate with the use of time, so the torque setting is too high, please reduce the current when using to avoid exceeding the rated torque.

(2) Although the torque decreases as the usage time increases, if the current is increased, the torque will increase accordingly, so stable torque can be transmitted. However, during use, do not apply a current exceeding the rated value.

Third, torque

(1) The current-torque characteristics described in the general product manual are standard values for new products at 200 r / min. Magnetic powder will deteriorate with time, so the standard characteristics will change with time. Correct the change in torque characteristics based on the current.

(2) Although the torque can be easily controlled using current, especially large models (torques above 100 N · m) are rotating at high speeds and the torque is often unstable when used under low current conditions. note.

(3) It is important to note that when ON / OFF control is performed during high-speed rotation, it may take considerable time to reach the specified torque.

(4) The torque deviation of each product near the rated current is about ± 10%. The deviation of the standard torque characteristics between products is more than ± 15%. Therefore, when the clutch and brake are operated in parallel, it is recommended that they be set to a mode where the current can be adjusted independently.

(5) Hysteresis due to torque value. Please note that a torque difference may occur due to the increase or decrease in current.

Product life

(1) When continuous slip is used during winding and unwinding, the life varies depending on the conditions of use (relative slip speed, etc.), but generally when used under continuous slip power, under rated current and torque The life of the magnetic powder when the rated torque is reduced is about 5000 to 8000 hours. Since it can be used below the rated torque, continuous continuous use is equivalent to extending the service life. Even with the same slip power, when the slip speed, that is, the relative speed continues to be high, the life time tends to shorten, so please set the relative speed as small as possible.

(2) Compared with the allowable continuous slip power, if it can be used in more abundant conditions, it can extend the life of the magnetic powder. For example, when used at 50% of continuous slip power, the life can sometimes be more than doubled.

V. Low-speed rotation (below 15r / min)

During continuous operation such as tension control, the torque characteristics are stable. However, in the intermittent operation with idling, a slight increase in torque often occurs after the voltage is directly applied. In order to avoid this, please follow the instructions below.

(1) Even at the end of unwinding, please keep the state of weak excitation (5 ~ 10% of the rated current), and do not let the magnetic particles fall from the work surface.

(2) Please accelerate and keep the minimum speed at 15r / min. However, due to the large acceleration and mechanical loss of the acceleration mechanism, you may not be able to perform accurate torque control, so please be careful.

Six, please carry out trial operation

(1) Due to the impact of external force during transportation, etc., the magnetic powder distribution inside the clutch and brake will be shifted, so please perform trial operation before the official operation.

(2) Sometimes the rotation of the shaft may be delayed due to the deviation of the magnetic powder distribution, or the shaft may feel locked, and abnormal noise may occur. In this case, use a plastic hammer to gently tap the outer periphery of the body. As long as it is in the running state, the offset problem can be solved.

Seven, when forced air cooling

(1) Please install an air filter

The compressed air of the cooling air usually contains oil and moisture. Be sure to use clean and dry air that has been treated with an air filter (completely degreasing).

(When using compressed air that has not been treated with an air filter, the performance of the magnetic powder will be significantly reduced due to moisture and oil stains.)

(2) When the air pipe is long or a bifurcated air pipe is used, please check whether there is more than a predetermined amount of air output near the clutch and brake suction pipe.

Eight, block cooling method

(1) Although an axial flow fan (blower) is provided, if the capacity of the axial flow fan is reduced and the heat dissipation effect is deteriorated, the allowable continuous slip power will be reduced. Therefore, be sure to reserve a certain space around the installation. . Especially when the surrounding environment is bad, foreign matter may be attached to the axial flow fan grille. Please clean it regularly.

(2) There is a thermal switch to detect the temperature on the outer circumference of the stator, so be sure to connect the switch to an alarm device to detect the temperature on the outer circumference of the stator.

Nine, the situation of water cooling

(1) Install a drain valve.

If you need to stop operation after long-term use, if cooling water accumulates inside, it will be detrimental to rust and moisture, so please install a drain valve on the water supply side to drain the cooling water. Please note that the cooling water may freeze and cause damage to the water pipe of the magnetic powder brake during the shutdown period in cold areas, etc.

Also, periodically clean up the scale (rust) that occurs in the cooling water pipe.

(2) Install a protective circuit in the event of a water cut.

Even if the water is cut off for a short time, the internal damage of the water-cooled brake may be caused. Therefore, install a water cutoff protection circuit (flow control relay).

(3) Please pay attention to condensation.

In order to prevent condensation caused by excessive cooling of water-cooled brakes, please pay attention to the following (when condensation occurs, the magnetic powder will affect its characteristics).

(a) Please provide the same water as room temperature. When the workload is small and the surface temperature is below 40 ° C, reduce the amount of water supply.

(b) Stop the water supply immediately after the operation is stopped.

(c) When used in turrets, etc., do not supply water to unused brakes.

(4) After the large magnetic powder brake is stopped and placed for a long time, sometimes the shaft cannot rotate. This is due to the phenomenon that the thermally expanded driving body shrinks during cooling and bites into the magnetic powder between the driven body and the driven body (magnetic powder gap) when operating under high load conditions. It only needs to rotate the shaft several times after the operation is stopped. , You can prevent this from happening in advance. If it cannot be rotated, you can use a plastic hammer or other tools to lightly hit the coupling mounted on the shaft, etc. (Do not directly apply excessive impact force on the brake body and the shaft).

Ten, selected

(1) Do not exceed the rated torque even within the allowable continuous slip power.

(2) When the tension control range is wide, sometimes multiple clutches can be set for switching. In this case, in order to prevent the unused clutch output from forcibly idling, use an electromagnetic clutch to release it.

Eleven, abnormal torque at startup

(1) Depending on the operation mode (when the rotation is stopped, the input shaft is rotated after the coil current is turned on, or the rotation is started while the coil current is turned on), a torque higher than the specified value (peak torque may be generated at the moment of startup) ). Especially in a state where the current is not turned on, vibration occurs and the magnetic powder distribution is shifted, which causes this phenomenon to be more significant. The countermeasure is to maintain a weak excitation current in the clutch and brake coil even when the operation is stopped, which can make this phenomenon less likely to occur.

(2) Peak torque also occurs when the magnetic powder is wet. At this time, depending on the current situation, the product may need to be replaced.

Twelve, other

(1) When using at high altitudes, due to the influence of air pressure, the allowable continuous slip power will be reduced. Please pay attention. This product is suitable for below 1000m.

(2) The magnetic powder clutch body may overflow magnetic powder oxide powder and fine powder, so it cannot be used in a highly dust-proof environment.

(3) Magnetic powder clutches and brakes do not generate connection sounds and brake sounds such as friction plate clutches and brakes. However, since magnetic powder clutches and brakes are friction clutches and brakes using magnetic powder as a medium, friction noise occurs. Although it does not affect the use of general machinery, the friction sound will increase due to the influence of the internal magnetic powder distribution. (Usually, the friction sound disappears after a trial run, or after a period of running time.)

(4) There is no problem when used under the vibration level of general printing machinery, paper processing machinery, packaging machines and other machinery without abnormal vibration, but it cannot be used on machinery with impact force.

(5) Magnetic flux will be generated when voltage is applied to the clutch and brake, and the assembly shaft and the like will be magnetized by the magnetic flux. If the magnetization affects the operation of the product, it is recommended to use non-magnetic materials for installation, but this problem cannot be completely solved.