The plate hammer is an important part of the impact crusher. When the material enters the action area of the plate hammer, it will be broken by the high-speed impact of the plate hammer and thrown to the impact plate installed above the rotor to break again, and then it will spring back to the action area of the plate hammer from the impact lining plate to break again. It can be seen that the plate hammer has direct contact with the material. The shape and fixing method of the plate hammer have a certain influence on the crushing. This paper mainly introduces two shapes and three fixing methods of plate hammer.

1.Two shapes of plate hammer
At present, the shape of plate hammer on the market is mostly divided into two kinds, one is linear plate hammer, the other is crescent plate hammer.
The crescent plate hammer has more advantages, because it can ensure the vertical impact of materials, with greater impact force and high crushing efficiency. Moreover, the impact surface is larger and more durable than the linear plate hammer.

2.Fixing method of plate hammer
The plate hammer needs to be fixed on the rotor in the impact crusher. There are three ways to fix the plate hammer:

2.1 Bolt fixing
The plate hammer is inserted into the corresponding slot hole of the rotor axially from the side of the rotor. In order to prevent the axial movement, the two ends are positioned by pressing plates. As the fastening bolts are removed, the working reliability of the plate hammer is improved. The centrifugal inertia force produced when the plate hammer rotates is used to fasten and self lock with the reaction force when the plate hammer impacts and breaks, and the replaceable structure form is made for the easily worn part of the rotor, so the loading and unloading is simple and the production is easy. However, the bolt exposed on the striking surface is very easy to be damaged, and the bolt is subject to large shear force, once cut, it will cause serious accidents.

2.2 Press plate fixation
The plate hammer is inserted into the groove of the rotor from the side, and the two ends are pressed by pressing plates. However, this fixation method makes the plate hammer not firm enough, and the plate hammer is easy to loosen during work, because the plate hammer manufacturing and processing requirements are very high, and alloy materials such as high manganese steel are not easy to process.

2.3 Wedge fixation
The wedge is used to fix the plate hammer on the rotor. Under the action of centrifugal force, the faster the rotor speed is, the firmer the plate hammer is fixed, and the work is reliable, and the removal and replacement is more convenient. This is a better way to fix the plate hammer at present, which is used in many countries. The wedge is made of cast steel, with certain toughness and plasticity, high strength and hardness, and good machinability.