Type selection and application examples of the hot

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Brake type, selection and application examples

1 function of brake

the working principle of the brake is to use the friction torque generated in the friction pair to realize the braking effect, or use the balance between the braking force and gravity to keep the running speed of the machine constant. In order to reduce the braking torque and the size of the brake, the brake is usually configured on the high-speed shaft of the machine

in addition to the direct drive flight of this kind of light, the type and characteristics of 2 brakes

according to the purpose:

stop type -- it plays the role of stopping and supporting moving objects

speed regulating type -- in addition to the above functions, it can also adjust the moving speed of objects

according to the structural characteristics: block type, belt type and disc type

according to the operation mode: manual, automatic and hybrid

according to the working state:

normally open -- it is often in the brake release state, and external force must be applied to realize braking

normally closed -- it is often in the closing or braking state, and the braking state can be released only by applying external force. Normally closed brakes are often used in hoisting machinery, while the main brakes of various vehicles are normally open

introduction to common brake

the working principle of short stroke electromagnet double pad brake is shown in the figure. In the state shown in the figure, the electromagnetic iron coil 5 is powered off, the main spring 8 disturbs the left and right brake arms 4, and the two pads 3 brake the brake wheel 10 at the same time. At this time, it is in the braking state. When the electromagnet coil is energized, the electromagnet 6 rotates counterclockwise around point O, forcing the push rod 7 to move to the right, so the main spring 8 is compressed, the distance between the upper ends of the left and right brake arms 4 increases, the two pads 3 leave the brake wheel 10, and the brake is in the open state. Two brake arms are symmetrically arranged on both sides of the brake wheel, and two pads are hinged on it, so that the positive pressure under the two pads is equal and the closing force on the two brake arms is equal, so as to eliminate the lateral force on the brake wheel. Installing the electromagnet on the brake arm can make the braking stroke shorter (less than 5mm). The pressure of the main spring can be adjusted by the nut installed on the push rod 7 at its end. The opening degree of the two brake booms is adjusted and limited by the limit screw 2

short stroke electromagnet double pad brake

the advantages of this brake are: rapid braking and opening, small size and light weight. When replacing pads and electromagnets, nizaki base will provide some samples and solutions according to the requirements of different customers, which is convenient, and it is easy to adjust the gap between pads and brake wheels. The disadvantages are: the impact force is large when braking, the electromagnet attraction required when opening is large, and the size and electric energy consumption of the electromagnet are also large

the belt brake is braked by the friction moment between the brake belt wrapped on the brake wheel and the brake wheel. The figure shows a simple belt brake. Under the action of the heavy hammer 3, the brake belt 1 is tightly wrapped on the brake wheel 2 to realize braking. When releasing the brake, it is realized by electromagnet 4 or manually lifting the heavy hammer. The structure of the belt brake is simple; Due to the large wrap angle, the braking torque is also large. However, the brake belt is easy to break due to uneven wear; The lateral force on the shaft is also large

simple belt brake

the figure below shows the working principle of the internal tension shoe brake. The two brake shoes 1 are hinged with the brake base plate of the frame respectively, and the brake wheel 3 is connected with the braked shaft. The inner cylindrical surface of the brake wheel is equipped with friction pads 6 made of wear-resistant materials. When the pressure oil enters the oil cylinder 4, it pushes the left and right pistons, and the two brake shoes compress the inner cylindrical surface of the brake wheel under the driving force F of the piston, so as to realize braking. When releasing the brake, relieve the pressure of the oil circuit, and the spring 5 shrinks, so that the brake shoe leaves the brake wheel to release the brake

internal tension shoe brake

3 selection and application examples of brakes

some widely used brakes have been standardized, and there are a series of products to choose from. The rated braking torque is the main parameter representing the working capacity of the brake. The braking torque is the main basis for selecting the brake model. The required braking torque is determined according to the specific conditions of different mechanical equipment. When selecting the brake, in order to make the brake safe and reliable, generally increase the required braking torque appropriately, that is, select the brake model according to the calculated braking torque TZC:

tz-- torque of the axle where the brake wheel is located, n · m; KZ -- braking safety factor, see table

tez-- the rated braking torque of the brake, see the brake product sample or check the mechanical design manual. Table braking safety factor

note: JC is called the working duration of the mechanism or the mechanical power on duration, which refers to the percentage of the power on time of the mechanism in a working cycle of the machine. That is: where t is the total time of a working cycle of the machine, and t is the duration of power connection of the mechanism in a working cycle of the machine

example 1

the following figure shows a lifting mechanism of a heavy machine, with the brake set on the high-speed shaft. As it is a lifting mechanism, the normally closed type is selected. Considering the characteristics of simple structure, convenient installation and small additional load, the electromagnetic double pad brake is selected


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