As an early developed crusher, the vertical shaft impact crusher (sand making machine) has been widely used in sand and gravel yards and has been recognized by users as the most effective sand making equipment, commonly known as sand making machine.
The vertical shaft impact crusher adopts the impeller diameter (or rotor diameter * motor power, etc.) as the classification standard. According to the impeller form, it can be divided into open and closed. Depending on whether the shell is equipped with a counterattack or not, it can be divided into stone and stone. There are four basic forms of crushing methods. (Compared with the crushing method of the sand making machine, you can click "Two crushing methods and two feeding methods of the sand making machine.") If you choose the wrong one, it will greatly affect your productivity! ”）
From an international point of view, the advanced technology of VSI crushers is reflected in three aspects: flexible mechanical properties, excellent design of wear-resistant materials and parts, and effective dust control. For the domestic market, at least the first two are common.
1. Technical performance of vertical shaft impact crusher
The open impeller of the vertical shaft impact crusher has a feed size of 100 to 150mm, and the open impeller vertical shaft impact crusher that has not yet been commercialized in China has been put on the market. Therefore, in the field of gravel, the household vertical vertical impact crusher can only be used as a tertiary or fourth-stage crushing equipment, and cannot be used as a second-stage crushing equipment like abroad.
The equipment with an impeller diameter of 1.6m and the matching motor power of the impeller owned by foreign companies are as high as 1103KW, which is suitable for various large-scale production lines, while the domestic vertical shaft impact crusher rarely exceeds 1.2m.
The advanced impeller passage can be varied from 3 to 7 with different configurations and speeds to accommodate different materials and feed grades, resulting in higher sand outflow and required fineness modulus. The domestic closed rotor is basically fixed as 4 channels and rarely changes, so it has poor adaptability to different working conditions.
2. Design of wear-resistant materials and parts of vertical shaft impact crusher
This is because the material pads are designed on the VSI crusher to replace the bushing as a consumable part. Therefore, improving the service life of wear parts can be broken down into two aspects: part design and wear material application. For example, second-generation impellers are designed to protect the outer diameter of hardfacing and wear-resistant materials. Now, advanced part designs have incorporated a material pad protection approach, which eliminates expensive chrome alloy steel surfacing welds.
Manufacturers of specialized VSI crushers already use ceramics to make wear parts, not just tungsten carbide and high-chromium cast iron. Ceramic materials can not only withstand higher temperatures, but also have particularly good corrosion resistance, so the wear resistance of materials with high humidity is good at high speeds. At present, the household vertical shaft impact crusher is made of cemented carbide and high chromium cast iron materials, which are of unstable quality, easy to corrode and wear, and easy to be broken by metal parts. Due to the obvious gap between the crushing equipment products used in sand and gravel yards at home and abroad, domestic high-end markets such as large sandstone fields still account for the majority of imported equipment.
There are many reasons why there is a gap between crushing machinery at home and abroad. In addition to subjective reasons such as insufficient investment in science, market demand is the main objective reason. In Europe and the United States, large-scale infrastructure construction has already passed. The market demand for sand and gravel materials is not large, and the requirements for environmental protection are also very high. It will inevitably form a high-concentration sand and gravel field to achieve environmental protection through large-scale production. High degree of automation and operability. However, China is in the midst of a period of large-scale infrastructure development. The demand for sand and gravel materials has increased dramatically everywhere. The sand and gravel fields that bloom everywhere are usually low investment, small in scale, and low in technology. Therefore, the gap with the international advanced level is obvious.
Although there is a huge gap between domestic and foreign crushing equipment, due to the shrinking local market and high production costs, foreign crushing equipment manufacturers are still exploring markets outside their home countries. This situation provides a huge development opportunity for domestic crushing machinery manufacturers. After all, China has low manufacturing costs and a good base for heavy industry. Through the introduction of international advanced technology, combined with production, learning, research, peer cooperation and division of labor, increase investment in scientific research, we will overcome the technology gap, so that China's crushing equipment products can better enter the domestic and foreign markets.