( Shanghai Sower Mechanical ＆ Electrical Equipment Co． ，Ltd． ，Shanghai 200070，China)
Abstract: An integral dispersing － grinding equipment combines a dispersing process and a grinding process． It can be used as disperser or basket mill, which achieves the “first dispersing and then grinding”process． Compared with conventional equipment，it is characterized by simplified process, easy- to-use，higher efficiency，convenient cleaning and color readjustment，less residue at container，cost-effective，safe and simple maintenance． This article discusses the structure of the equipment and its feasibility to achieve the integral dispersing and grinding performance in one machine．
In the coating production process, for liquid materials containing powder aggregates, a disperser is required to pre-dispers the materials in the container, and then the fully dispersed materials are transported to the sand mill and ground to the fineness required by the process . However, in this production process, pipelines, pumps, and containers to be changed back are required. The entire operation process is relatively complicated and the efficiency is low; returning to the container changes will cause a lot of material residue, resulting in waste of raw materials and increased costs. At present, the existing basket mill has a certain dispersing capacity, but its dispersing and grinding are performed on two equipments, so it cannot be automated in production, and the separate dispersing has a poor effect and cannot guarantee the product quality. Especially for materials with high solid content or high viscosity, if the basket grinder is used for grinding directly, it will not be able to achieve a good grinding effect and the product quality cannot meet the standard. Therefore, a disperser must be used for pre-dispersion. At present, coating production equipment capable of both pre-dispersing materials and grinding the dispersed materials is not widely used. This research compares and analyzes the traditional equipment for coating production and the integrated dispersing and grinding machine, and introduces the structure of the basket grinding machine, and discusses the feasibility of its application.
1 Principle analysis
1.1 Traditional equipment for paint productionIn the coating production process, the traditional process flow (shown in Figure 1) is to use a separate disperser to pre-disperse and mix the slurry. After sufficient mixing and dispersing, pump it into a sand mill. The mill grinds the solid particles and stores them in a reserve container. If the fineness after sand grinding does not meet the requirements, re-pump into the sand mill for grinding until the fineness reaches the requirements.
In FIG. 1, the dispersing machine 1 disperses the materials to be mixed in the container 2. After being thoroughly mixed and dispersed, the container 2 is transported to the sand mill 4 and sent by the pump 3 to the sand mill 4. After being ground by the sand mill 4, it is sent to a container 5 for storage. If the fineness is not satisfactory, change container 5 to container 2. After repeated grinding, check that the fineness of the material in container 5 meets the process requirements, and stop the grinding operation. At this time, the material in the container 5 is a semi-finished coating.
The process is simple to operate, but involves more manual labor and greater labor intensity. Frequent container replacement will produce a lot of material residues, causing waste of raw materials.
1. 2 Dispersing and Grinding Machine
The integrated dispersing and grinding machine (as shown in Figure 2) has changed the traditional coating production process. The two processes of dispersing and grinding are concentrated on one machine. The operation is simple and convenient, the waste is small, the quality is easy to control, and it is easy to realize process automation.
The dispersing and grinding integrated machine is used to grind fine and extremely fine solid components in liquid phase. The grinding process is divided into the following 4 steps.(1) Under the action of the high-speed rotating dispersing material, the large particle aggregates (powder agglomerates) are dispersed to form small particle aggregates.(2) Stabilize the initial particles, lumps and aggregates to prevent re-consolidation.(3) The grinding basket is lowered to the working position, and the material to be ground is sucked into the grinding basket. When the lever on the lever impeller rotates at high speed, the grinding beads are turned to refine the material.(4) The material is discharged from the bottom of the grinding basket through the dense screen.
It can be seen from FIG. 2 that during the dispersion process, the dispersion plate 1 is at the working position, and the grinding basket 2 is at the parking position. At this time, the high-speed rotating dispersion disc 1 pre-disperses the material. During the grinding process, the grinding basket 2 and the dispersion plate 1 are in the working position at the same time. The material to be ground is sucked into the grinding basket. Discharge from the bottom of the grinding basket. The integrated dispersing and grinding machine realizes two steps of dispersing and grinding in one machine and one step, and can also be used as a dispersing machine alone. It can also achieve good grinding effect for materials with high solid content and high viscosity. The process is simple, less time consuming, high efficiency, less residue, easy to clean and change colors.
2 Structure of the dispersing and grinding integrated machine
2.1 StructureThe structure of the dispersing and grinding integrated machine is shown in Figure 3.
Hydraulic lifting base frame 1: The basic structure is composed of a base, a column, a lifting cylinder, a beam, etc., and other mechanisms are mounted on it. Dispersion part 7: One of the working parts, as shown in Figure 3 (2), including the active pulley 15, the main shaft 16, the dispersion frame 17, the lower clutch 20, the dispersion plate 25, etc .; Bearings are used to support the main shaft; when the grinding parts are in the parking position, only the dispersing parts work to disperse the material. Grinding part 8: one of the working parts, as shown in Figure 3 (3), including the upper clutch 18, the grinding frame 19, the grinding basket 21, the lever impeller 22, the grinding beads 23, the screen 24, etc .; In the working position, the grinding part will grind the material. Transmission system 13: Provide power for the dispersing or grinding parts, and transfer the kinetic energy of the main motor to the dispersing parts through a pair of pulleys; according to the needs of the production process, when the 2 cylinders of this equipment are ventilated, they are pushed down to make the upper clutch The lower clutch is accurately engaged, so that the kinetic energy of the main motor is transmitted from the dispersing member to the grinding member.Electrical control system 14: The control system adopts PLC controller and touch screen, which is accurate in control, simple in operation and safe in use.
2. 2 working process
As shown in Figure 3 (2), the grinding part is in the parking position, and the grinding part does not touch the material to be dispersed at this time. The grinding frame 19 is not driven when in this position. The pre-dispersion is performed only by the rotation of the dispersion plate, and the height of the dispersion plate can be adjusted to ensure proper processing conditions. The ideal “donut diagram effect” in pre-dispersion can be achieved. At this time, the grinding part does not hinder the circulation of the material to be dispersed (indicated by the arrow), so that the dispersion plate can be effectively and quickly pre-dispersed.As shown in Figure 3 (3), after the two cylinders are ventilated, the upper clutch 18 and the lower clutch 20 are accurately meshed, so that the dispersing part drives the grinding part to rotate through the clutch; at this time, the grinding basket 21 is at the lowest position and completely immersed until it is ready In dispersed materials. The grinding frame 19 rotates the paddle wheel 22 relative to the grinding basket 21. The paddle impeller 22 moves the grinding beads 23 to grind the material in the grinding basket. A mesh plate 24 is installed in the lower part of the grinding basket. When the dispersion plate 25 is rotating at a high speed, the centrifugal force causes a negative pressure in the center of the dispersion plate, and the refined material in the grinding basket is sucked out through the mesh plate; through such circulation and flow During the process, the material is finely dispersed and ground.
3 ConclusionThe integrated dispersing and grinding machine has the advantages of dispersing machine and basket type grinding machine. It is an organic combination of two types of equipment.In recent years, the integrated dispersing and grinding machine is suitable for the mixing and grinding of solid particles and liquid phases. The application in coating production has received certain attention, and certain economic and social benefits have been obtained.