Hydraulic Shear

What Is The Main Difference Between Heavy-duty Hydraulic Shears And Light-duty Hydraulic Shears For Aluminum Strips?

In the production of aluminum strip hot-rolling mills, when the first few passes are rolled, the head and tail of the strip often appear "open mouth", which affects the subsequent biting and transmission of the slab, so hydraulic shears are needed. Cut off the cracked head and tail of the strip. At this time, the thickness of the strip is often thicker, about 80~150mm, so the required shearing force is relatively large, so it is called a heavy-duty hydraulic shear. After the strip rolling is completed, if the product is a plate, it is often necessary to cut to length at this time, then the hydraulic shear is called a light hydraulic shear, and the object of the light hydraulic shear is mainly thin plates.

Working Principle of Hydraulic System

• The working pressure of the system is determined by the type of equipment, the size of the load, the structural requirements and the technical level. High working pressure, material saving, structure saving, compact structure and light weight are the current development direction of hydraulics, but attention should be paid to the proper handling of omissions, noise control and reliability issues. Due to the large shear force of this equipment, according to the production experience of the factory, after analyzing and considering various related factors, the system pressure is set to 20Mpa.

  
  

• When designing the principle, pay attention to the following issues:

  During the movement of the upper tool post, there is an idle stroke, and the system does not perform work. Therefore, the stroke of the hydraulic cylinder has two stages: idle stroke and power stroke. The idle stroke requires low pressure and large flow, and the power stroke requires high pressure and small flow. Consider carefully when calculating the motor power and the parameters of the accumulator.

  
  

• When the upper tool post moves downwards and the cutting blade has not cut, the resistance that the system needs to overcome is relatively small, and the upper tool post itself has a relatively large weight, which belongs to a gravity system. The system requires that the speed of the upper tool post be controlled at this time, otherwise, overspeed will occur. A balance valve should be added to the system to ensure the safety and reliability of the shearing machine. But note that two balance valves cannot be used.

  
  

• When the upper tool post is fast-forwarding, the system has a large flow rate and should be controlled by a cartridge valve. The flow rate of the cartridge is large, which can meet the requirements of the system, and the secondary control can adopt the electro-hydraulic directional valve.

  
  

• Based on the working principle of the shearing machine, the system is easy to adopt a manual variable constant power axial piston pump. Constant power can adapt to the two incompatible tasks of the shearing machine's empty stroke and cut stroke.