The shape characteristics of aggregate directly affect the performance of concrete. The crushing equipment is the main factor that produces these shape characteristics.
Comparison of the shapes of sand & gravel aggregates produced by 6 common crushers
Spring type cone crusher (worst shape)<<single-cylinder hydraulic cone crusher<multi-cylinder hydraulic cone crusher<hammer crusher<impact crusher<vertical shaft impact crusher (optimal cubic shape)
A Cone crusher is a compression crushing equipment. The multi-cylinder hydraulic cone crusher can realize “laminated crushing”, and the aggregate can be cubic. However, single-cylinder and spring cone crushers are difficult to form a “laminated crushing” effect due to the machine structure, so the shape of the aggregate is not the best cubic shape.
Impact crushers and hammer crushers are impact crushers. They use a high-speed rotating rotor to impact materials, and the materials can also impact the materials during the flight. The impact grinding between the stones will make the stones It is more rounded, so the aggregate of impact crusher and hammer crusher is cubic shape.
The difference between the impact crusher and the hammer crusher is that: the hammer head of the hammer crusher is divided, which causes the hammer crusher to crush materials in three ways, some of which are broken by the hammer (shear Cut), part of it is the impact between the material and the material during the impact (impact), part of the stone is impacted on the impact plate (impact), and part of it is crushed (grinding).
The blowback of the counterattack is fixed, and it is mainly broken by the impact of the rotor on the counterattack plate. The compressed and crushed particle shape is not as good as impact crushing, so the crushed stone aggregate crushed by the impact crusher can obtain the optimal cubic shape.
- A Spring cone crusher has limited pressure value due to the elastic coefficient of the spring, so it is difficult to form a lamination effect, especially when a large piece of material falls into the crushing equipment, it may directly exceed the spring elastic coefficient and cause material accumulation.
- The hydraulic cylinder of the single-cylinder hydraulic cone crusher is at the bottom of the machine body structure and cannot form uniform pressure around it. When large particles on one side pass through, it is easy to cause a layer of discharge opening to be too large, so that the residence time of the material is too short. It is difficult to form a material layer, so that the material is directly discharged from the discharge port without being broken.
- The multi-cylinder hydraulic cone crusher has at least 6 hydraulic cylinders to maintain uniform pressure. When crushing large pieces of material, it will not affect the discharge port of the crushing cavity. The material layer formed by both large pieces of material and small pieces of material is in Under pressure, it can truly realize the effect of lamination and crushing.
- The hammer head of the hammer crusher has a shearing effect. The materials crushed by the hammer crusher will form internal cracks, which can promote some materials to be squeezed and ground at the bottom of the hammer crusher, so cement plants like to use it. The hammer crusher crushes materials, which is convenient for the ball mill in the subsequent process to grind materials. However, in the aggregate industry, this kind of crack will cause the aggregate to absorb water and expand and reduce the compressive strength. Therefore, high-quality sand and gravel aggregates are not suitable for crushing with a hammer crusher.