Views: 0 Author: Site Editor Publish Time: 2022-07-28 Origin: Site
The buffer in the cylinder is used to slow down the moving load of the piston. If the cushioning device is not used, when the piston moves to the end, especially long stroke pneumatic cylinders, the kinetic energy of the piston hitting the end cover will be very large. This can easily damage the parts and shorten the life of the cylinder. What's more, the noise caused by the impact is also terrible. If the noise of a cylinder without a buffer device is 70dB, the noise of the entire factory will be as high as 140dB, just like being on the runway of a jet airplane for a long time. This has reached the limit that human beings can't stand and suffer. How to solve these problems?
When the movement speed of the pneumatic cylinder actuator at the end of the stroke is relatively high, the cushion pad alone is not enough to absorb the impact force of the piston on the end cover, and a pneumatic cushion device can be installed in the cylinder.
For small-bore long-stroke cylinders without cushion valves, a small horizontal orifice is opened in the end cover. When the piston moves to the end of the stroke, a large back pressure is formed due to poor exhaust, which can also play a role in air cushioning. This structure is called an unadjustable air cushioning cylinder. Enlarging the constant orifice can increase the movement speed of the cylinder.
For cylinders with large moving parts and high moving speeds, when the excessive impact energy cannot be completely absorbed by air buffer alone, a buffer device (such as hydraulic buffer or air cylinder control valve) must be installed externally or a buffer circuit must be used to solve the problem. .
There are currently three common ones. The first is that the cylinder bore is relatively small and uses hard buffering, which is to add anti-collision pads to the cylinder head. There are iron and plastic options. The second is air cushioning, that is, threaded holes are drilled near the intake port to pass into the cylinder and can be adjusted. The size of the cylinder's cushioning is adjusted by the flow rate when exhausting. Most of the current cylinders use this. The third is the use of hydraulic buffers, which are shock absorbers, which are used for buffering when the cylinder is about to reach the end point. This type of buffering is more accurate and effective, and the cost is higher.
1. Hydraulic buffer
Installing a hydraulic buffer at the front end of the cylinder is the simplest method of cylinder buffering. Through the unique orifice design, mineral oil is used as the medium to smoothly realize the transition from high speed and light load to low speed and heavy load. The hydro pneumatic cylinder can play its role here.
2. Rubber cushion
Rubber buffer means that buffer pads are set on both ends of the piston rod. This is mostly used for small air cylinders to prevent operating noise. However, we must pay attention to the phenomenon of deformation and peeling caused by the aging of the rubber.
3. Air cushion
When the piston moves, the buffer sleeve and the sealing ring work together to form a closed air chamber/buffer cavity on one side to realize buffering.
Determine the thrust and pull force on the piston rod according to the force required for the work. Therefore, when selecting the cylinder, the output force of the cylinder should have a little margin. If the cylinder diameter is selected smaller, the output force is not enough, and the cylinder cannot work normally. However, the cylinder diameter is too large, which not only makes the equipment bulky and costly, but also increases the gas consumption and causes energy waste. When designing the fixture, try to use pneumatic boosting cylinder, pneumatic impact cylinder or spring loaded pneumatic cylinder.