Overview

In modern industrial production, CNC plasma cutting is compared with traditional flame cutting technology. CNC plasma cutting machine technology has high cutting accuracy and fast cutting speed in the process of cutting metal sheets, so it is increasingly widely used in the machinery industry. Generally, large-scale CNC plasma cutting machines will generate a lot of smoke and dust when cutting steel plates. The smoke and dust are sprayed from below the workpiece and distributed in the workshop, causing the workshop to be filled with smoke and dust. The working conditions of workers are extremely bad, which not only affects the health of the workers, but also greatly reduces labor productivity. This has brought more and more serious pollution problems, and the smoke and dust control of CNC plasma cutting machines is becoming more and more urgent. In order to strengthen labor protection, improve working conditions and increase labor productivity, in order to fundamentally improve the labor environment, ensure the healthy conditions of workers in the labor process, and at the same time increase labor productivity. Our company provides your company with a good design scheme of smoke and dust purification system.

Second, the general treatment method of the smoke and dust of the CNC plasma cutting machine

At present, there are generally two ways to control the smoke and dust of cutting machines: wet treatment and dry treatment.

1. With the increasing calls for energy conservation, emission reduction, and environmental protection in my country, most companies have given priority to adopting plasma underwater cutting methods in recent years. The so-called wet treatment method is to set up a water bed under the plasma machine cutting platform, so that the workpiece is placed in water, and the cutting operation is completed underwater, so that the oxides produced by the cutting are captured by the water to achieve the purpose of purifying the working environment. This treatment method only needs to manufacture a water container, and one-time investment is low: but this treatment method will cause secondary pollution (water pollution), and metal oxides are easy to compact underwater and difficult to clean. And for users in the north, the colder weather in winter will cause the water in the cutting platform to freeze, which brings inconvenience to cutting, and this treatment method is not suitable for the purification of metal cutting smoke and dust such as aluminum and magnesium that generate explosive dust during cutting. Another disadvantage of wet dust removal is that the steel plate is prone to rust in contact with water during cutting, and the underwater cutting efficiency is low.

2. The dry treatment method is also constantly updated with the development of CNC plasma cutting machines. It was used very early to add a movable suction hood to the cutting head, but in practical applications, it was found that the steel plate and the cutting position The gap is relatively narrow, most of the smoke and dust are in the lower part of the steel plate, and the upper dust hood cannot achieve the effect of smoking and dust removal.

The overall design ideas

Generally, large-scale CNC plasma cutting machines will generate a lot of smoke and dust when cutting steel plates. The smoke and dust are sprayed from below the workpiece and distributed in the workshop, causing the workshop to be filled with smoke and dust. The working conditions of workers are extremely bad, which not only affects the health of the workers, but also greatly reduces labor productivity.

In order to strengthen labor protection, improve working conditions, and increase labor productivity, the Institute of Science and Technology has newly developed a plasma cutting dust removal system. A large amount of smoke and dust generated during cutting are immediately removed from the bottom of the platform, logically controlled, and automatic segmented exhaust. This saves operating costs. The labor environment is fundamentally improved, the healthy conditions of workers in the labor process are ensured, and labor productivity is increased.

The dry treatment method is to add a set of smoke and dust trapping devices to the working platform of the CNC plasma cutting machine. After the disposal reaches the standard, it will be discharged. The smoke and dust generated by plasma cutting are basically formed under the cut of the workpiece, so the suction type negative pressure cutting platform has become a very common smoke and dust collection device at present. In order to save equipment investment and improve the ventilation efficiency, that is to achieve a higher collection of smoke and dust with a smaller suction volume-only the area that is in the cutting process is vacuumed, so the cutting platform will be divided along the main guide rail of the cutting machine It is a small confined area with an air outlet on the side. The working form of the suction port is divided into a side suction mobile suction port and a valve suction port on the side wall of the vacuum chamber. Among them, the former is widely used because of its simple structure, reliable work and better dust removal effect.

Fourth, the composition and working principle of the cutting dust removal system

In order to save investment on the premise of ensuring the filtering effect, we adopted the method of dividing into parts in the design, dividing the exhaust workbench under the workbench of the CNC plasma cutting machine into several small rooms of equal geometric size. Each small chamber is integrated with the main suction pipe through a controllable valve, and the valve opening control is realized by an induction mechanism integrated with the cutting head mounting seat, so that the small chamber corresponding to the position of the cutting head during the cutting operation The valve is always in the open state, while the valves in the other chambers are in the closed state. In this way, the suction volume is greatly reduced, thereby saving equipment investment. In this way, the air volume of the fixed dust removal system is related to the width of the cutting platform. Generally, a relatively large air volume is required to have a better dust removal effect. The dust removal system of the CNC cutting machine consists of a cutting platform, an exhaust pipe, a dust collector and a control system.

The cutting platform is composed of a workpiece support frame, a slag bucket, and a platform base frame. The cutting platform is divided into several different intervals in the horizontal direction. The size is 1.2m×2.0m. There are two air ducts running through the entire length on both sides of the longitudinal direction. Each horizontal interval of the cutting platform is connected to or separated from the longitudinal air duct. . There is a slag hopper in each interval to contain the metal slag and metal scraps generated during cutting, and the slag hopper can be lifted out to remove if necessary. There is an exhaust vent on each side of the slag hopper. The workpiece support plate is fixed on the upper part of the cutting platform to support the workpiece. The workpiece support plate is detachable for easy replacement (the design width of the grille on the upper part of the cutting platform is about 0.5m).

Under the more economical energy consumption, the working surface of the platform has an appropriate downward wind speed to ensure that the smoke does not escape. The dust collector is used to remove the particles in the smoke and dust to ensure that the emission meets the environmental protection requirements. Start the ventilator before the cutting work, so that the air passes around the workpiece at the corresponding interval at the position of the frame, with the smoke and dust generated by the cutting, enters the longitudinal air duct through the slag bucket vent at this position, passes through the air duct, and is filtered by the dust collector After being discharged into the atmosphere.

The coverage of the steel plate on the upper part of the CNC plasma cutting machine has a great relationship with the exhaust air volume. Our company is designed to cover an average of more than 50%. For the cutting work platform with a width of 4.0m, the air volume is 16000m3/h, so the air volume on both sides It is: 16000m3/h×2=32000m3/h, considering the sealing problem of the air duct pneumatic butterfly valve, the final air volume is 35000m3/h.

The benefits of the above governance methods

1. Dry cutting is much more efficient than cutting on the water;

2. The exhaust duct takes away most of the heat in the cutting process, has a great protective effect on the cutting head, and improves its service life;

3. There is no moisture and smoke on the upper part of the steel plate during the cutting process of the CNC plasma cutting machine, which makes the cutting more accurate and precise.

4. When cutting aluminum, magnesium and other oxide and water explosive objects, the number of workers is greatly increased;

5. Compared with wet method, dry dust removal reduces secondary pollution, and the cutting slag is easy to clean;

6. The working grille is detachable, which is convenient for slag cleaning, maintenance and replacement of the grille;

Sixth, the selection design of the dust collector

1. The purification of dust can only be achieved by the dust collector. The choice of the dust collector directly affects the collection effect of the dust removal system, the power consumption of dust removal, and the long-term stable and reliable operation of the entire system. There are many forms of dust collectors, and each has its advantages and disadvantages. The key is how to maximize its strengths and avoid weaknesses, and adapt to the system process and dust composition to obtain a good governance effect. In order to make the dust collector operate better, the filter wind speed in each system is determined to be <1.5m/min.

2. The LDCM series long bag pulse dust collector is a collection of years of research and technical experience and results, combined with the current excellent long bag pulse dust removal technology, and introduced to users a level of long bag pulse dust collector technology and products . It is a kind of dust removal equipment with good dust removal effect, high dust removal efficiency, reliable operation and convenient maintenance.

3. Control system The control system can be manual and automatic. The humanized design of the pulse cleaning mechanism, the PLC control cabinet independently completes the filtering and cleaning and unloading work, and the operation is simple.

The working principle of the dust collector

The dust collector is mainly composed of upper box body, middle box body, ash hopper, bracket, filter bag and ash removal device, ash unloading device and so on. Dust-laden air enters the ash hopper of each chamber from the air inlet duct of the dust collector. Large particles of dust are separated and directly fall into the ash hopper, while the finer dust evenly enters the middle box and is adsorbed on the outer surface of the filter bag, making it clean The gas enters the upper box body through the filter bag, and is discharged into the atmosphere through the clean air box. As the filtering conditions progress, the dust on the filter bag accumulates more and more. When the equipment resistance reaches the limited resistance value (generally set to 1500Pa), the ash cleaning control device will set the value or the ash cleaning time according to the differential pressure. Set the value, turn on the ash-removing fan according to the set program to remove the ash, shake off the dust on the filter bag (even if the fine dust can be cleaned more thoroughly) into the ash hopper, and discharge it by the ash discharge mechanism.

8. Regarding the noise and arc generated in the production process

For the noise generated by the CNC plasma cutting machine during work, a part of it can be taken away by the newly-added exhaust duct of the agency, but it has not been successfully reduced to below 85 Ba. It is very difficult to control the arc light generated by the CNC plasma cutting machine at work. The smoke, steam and most of the heat generated by the exhaust duct are sucked away. There is no dust and water vapor around the cutting machine. The arc light cannot form diffuse reflection of light. , Which reduces the reflection area.