Screw conveyors are divided into two types: shaft screw conveyors and shaftless screw conveyors. They are divided into U-shaped screw conveyors and tube screw conveyors. Axle screw conveyors are suitable for non-adhesive dry powder materials and small particle materials (eg cement, fly ash, lime, grain, etc.) and shaftless screw conveyors suitable for conveyors made of viscous and easily-wound materials. (Such as: sludge, biomass, garbage, etc.) The working principle of the screw conveyor is that the rotating spiral vane transfers the material and conveys it through the screw conveyor. The force that the material does not rotate with the screw conveyor blade is the weight of the material itself. The friction resistance of the screw conveyor casing to the material. Spiral blades welded on the rotating shaft of the screw conveyor. The surface shape of the blade has different types such as solid surface type, belt type surface, and blade surface type according to the material to be conveyed. Spiral conveyor screw axis in the direction of material movement in the end of the thrust bearing with the material to the spiral of the axial reaction force, in the captain is longer, should be added to the middle of the hanging bearings.
The screw conveyor is divided from the angle of the direction of the displacement of the conveying material. The screw conveyor is divided into two types: a horizontal screw conveyor and a vertical screw conveyor.
According to the conveyor chain, the screw conveyor made of high-strength plastic is also called food screw conveyor. The spiral elevator is mainly used to transport large products. Such as carton, turnover box, bottled water and so on.
According to the characteristics and requirements of the conveying materials, screw conveyors include horizontal screw conveyors, vertical screw conveyors, flexible screw conveyors, and spiral tube (roller conveyor) conveyors.
(1) Vertical Screw Conveyor
The screw speed of the vertical screw conveyor is higher than that of the ordinary screw conveyor. The added material under the action of centrifugal force generates friction with the housing. The friction force prevents the material from rotating along with the screw blade and overcomes the material drop. Gravity, thus achieving the vertical transport of the material. The machine has a small amount of conveying, small conveying height, high speed, and high energy consumption. It is especially suitable for conveying powdery granular materials with good fluidity, mainly used for lifting materials, and the lifting height is generally not more than 8 meters.
(2) Horizontal screw conveyor
When the material is added into the fixed machine slot, due to the gravity of the material and the friction between the material and the machine slot, the material accumulated in the lower part of the machine slot does not rotate with the spiral body, but only moves under the push of the rotating spiral blade, as if The non-rotating nut performs the translational movement of the rotating screw to achieve the purpose of conveying the material. The machine is convenient for loading and unloading at multiple points, and the mixing, stirring or cooling functions can be completed simultaneously during the conveying process. Sensitive to overload, easy to plug; The material has crushing loss, the structure of the horizontal screw conveyor is simple, easy to install and repair and troubleshooting. Suitable for horizontal or slightly inclined (20º below) continuous and uniform conveying loose material, working temperature is -20-+40°C, conveying material temperature is -20-+80°C. Its rotation speed is lower than that of the vertical conveyor. It is mainly used for conveying materials in horizontal or small angles. The conveying distance is generally not more than 70 meters.
(3) Spiral tube (roller conveyor) conveyor
Spiral tube conveyor is welded in the cylindrical shell with a continuous spiral blade, rotating with the spiral shell. The added material is rotated and lifted by random shells due to the effect of centrifugal force and friction, and then slides down along the spiral surface under the gravity of the material, so that the material rotates along with the spiral tube to realize the forward movement of the material, as if not rotating The screw follows the rotating nut for translational movement to achieve the purpose of conveying the material.
The machine has low energy consumption and low maintenance cost; when feeding at the end, it can adapt to the uneven feeding requirements, and can simultaneously fulfill various technological requirements such as conveying, stirring, mixing, etc. When the materials enter too much, it will not cause jamming phenomenon; Point loading and unloading, can transport higher temperature materials. It is suitable for conveying high-temperature materials horizontally; it has better adaptability to the materials with high temperature, uneven feeding, anti-crushing requirements, anti-pollution requirements, and processes requiring multi-point loading and unloading. Practice has proved that it works well when transporting cement clinker, dry limestone, phosphate rock, ilmenite powder, coal and slag.
The material added by the end inlet shall not have a particle size greater than 1/4 of the diameter of the screw; the material fed from the intermediate inlet shall not exceed 30 mm in size. In order to ensure that the cylinder does not deform, the feed temperature must be controlled below 300°C. The machine wears blades and troughs very seriously when transporting abrasive materials. The screw conveyors designed this time are mainly used for conveying silicon micropowders and have a large grinding capacity, so it is not suitable to use spiral conveyors.
(4) Flexible screw conveyor
The spiral body spindle of the machine is flexible, so the transmission line can be arranged according to the space curve as required. According to the ratio of the length of the horizontal and vertical (large dip) sections of the layout line, its working principle is designed as an ordinary screw conveyor or a vertical screw conveyor.
For the transmission line needs to be arranged according to the space curve, to avoid the occasion of material transfer; when the housing enters too much material or there is a hard block material, the spiral body will float freely, will not produce blocking phenomenon; the noise is small. It is mainly used for the horizontal and vertical conveying of materials at the same time. When transporting vertically, it is generally required that the rotation speed should not be lower than 1000 r/min.
When the screw shaft rotates, due to the gravitational force of the material and the friction generated by the wall of the tank body, the material can only move forward along the groove bottom of the conveyor under the pushing of the blade, and the condition is like the non-rotatable nut edge. The rotating screw is the same as the translational movement. The movement of material in the middle bearing is based on the thrust of the material moving forward. Therefore, the transport of material in the conveyor is completely a kind of slip movement. In order to make the screw shaft in a more favorable tension state, the drive device and the discharge port are generally placed at the same end of the conveyor, and the feed port is placed as close as possible to the tail of the other end. The rotating spiral vane conveys the material while being conveyed, so that the force that the material does not rotate with the screw conveyor blade is the weight of the material itself and the friction resistance of the screw conveyor housing to the material. The surface of the blade has different types such as solid surface type, belt type surface, and blade surface type depending on the material to be transported. Spiral conveyor screw axis in the direction of material movement in the end of the thrust bearing with the material to the spiral of the axial reaction force, in the captain is longer, should add the middle of the hanging bearing.
Closing of the tank and the spiral composition by the drive means the coal in the tank is transferred by screw rotation.
The features are: simple structure, small cross-sectional size, good sealing, reliable work, low manufacturing cost, easy loading and unloading in the middle, reversible conveying direction, and simultaneous conveying in the opposite direction. The material can also be agitated, mixed, heated, and cooled during transportation. Through the loading and unloading gate can adjust the material flow. However, it is not suitable to transport perishable, viscous, agglomerate and bulk materials. In the process of conveying, the materials are easily broken, and the spiral and feed trough are easy to wear. The unit power is larger. Keep the tightness of the feed trough and proper clearance between the screw and feed trough during use.
Vertical screw conveyors are suitable for short vertical transport. The spiral of the flexible screw conveyor is composed of a flexible shaft and a synthetic rubber blade, which is easy to bend and can be freely arranged according to site or process requirements for space transportation. Spiral conveyor blades are now pull-type and pull-out, now pull-type can be made of any thickness and size specifications, the entire pull-style should not be made of non-standard spiral.
From the perspective of the direction of displacement of the material to be transported, Hongtai screw conveyors are divided into two types: horizontal screw conveyors and vertical screw conveyors. They are mainly used for loose materials such as powder, granules and small pieces. Horizontal conveying and vertical lifting, the screw conveyor is not suitable for conveying special materials that are easily deteriorating, sticky, easy to agglomerate or have high temperature, pressure, and corrosivity.
The screw conveyor is generally composed of three parts: the conveyor body, the inlet and outlet, and the driving device; the helical blades of the screw conveyor have three types: a solid spiral surface, a belt spiral surface and a blade spiral surface. Among them, the blade spiral surface application Relatively few, mainly used for conveying more viscous and compressible materials. This screw-suspension type has the functions of agitation and mixing of materials at the same time during the completion of the conveying operation.
Compared with other conveying equipment, the screw conveyor has the advantages of small size of the cross section, good sealing performance, stable and reliable operation, multi-point loading and unloading, safe operation, and easy maintenance.
Screw machine is widely used in various industries, such as building materials, chemical industry, electric power, metallurgy, coal, coal, food and other industries, suitable for horizontal or inclined conveying powder, granular and small pieces of materials, such as coal, ash, slag, cement, food And so on, the material temperature is less than 200 °C. Screw machines are not suitable for conveying highly viscous, highly viscous, easily agglomerated materials. In the concrete mixing station, the effect of the screw conveyor has been maximally reflected.
During the use of the screw conveyor, it is necessary to pay attention to the daily maintenance and maintenance, so that it can best cooperate with the sand dryer to ensure the production volume and efficiency, and also to extend the service life of the equipment.
(1) Lubricate the bearings, gears, chains, etc. regularly.
(2) After the box conveyor is deactivated, check the wear condition of the spiral blades and repair the welding if the wear is serious.
(3) The transport volume should not be overloaded, otherwise the material could not be discharged, causing the screw shaft to bend and the box to deteriorate.
(4) When the medium to be transported has a high temperature, it is necessary to pay attention to whether the expansion and contraction of the box is free and where there is no jamming.
(5) When the conveyor is in operation and the noise emitted is harsh, it should be checked and troubleshooting.
Application and features:
First, the selection of screw conveyor
(A) Application scope and features
(1) Screw conveyor is a kind of conveying equipment widely used in chemical, building materials, grain and other departments. It is mainly used for conveying powdery, granular and small-sized materials. It is not suitable for conveying perishable, viscous, and agglomerated materials.
(2) The ambient temperature of the screw conveyor is -20~50°C; the angle of inclination of the conveyor is ≤20°; the length of the conveyor is generally less than 40m, and the maximum length is no more than 70m.
(3) Compared with other conveying equipments, spiral conveying has the advantages of simple structure, small cross-sectional size, good sealing performance, multi-point loading and unloading, safe and convenient operation, and low manufacturing cost. Its disadvantages are that the parts wear more severely, the delivery volume is lower, the power consumption is greater, and the materials are easily broken during transportation.
(B) Classification and Structural Features
(1) The helical blades of the screw conveyor have three types: solid spiral surface, belt spiral surface and blade spiral surface. The spiral helix is called the s method. The helical pitch GX is 0.8 times the diameter of the blade. The LS screw conveyor is suitable for conveying powdered and granular materials. The spiral helicoid, also called D method, has the same helical pitch as the diameter of the spiral blade and is suitable for conveying powdery and small pieces of material. The blade spiral surface is less used, and it is mainly used for conveying materials with high viscosity and compressibility. During the conveying process, the stirring and mixing processes are completed at the same time. The spiral pitch is about 1.2 times the diameter of the spiral blade.
(2) The helical blades of the screw conveyor have two directions of left and right rotations.
(3) Screw conveyors are horizontal fixed screw conveyors and vertical screw conveyors. Horizontal fixed screw conveyor is the most commonly used type. The vertical screw conveyor is used to lift materials at short distances. The conveying height is generally not more than 8m. The spiral blades are solid surface type. It must have horizontal spiral feeding to ensure the necessary feed pressure.
(4) LS, GX screw conveyor material outlet end, should be set to 1/2 to 1 turn reverse spiral chip to prevent powder blocking the end.
(5) The screw conveyor consists of three parts: screw body, inlet and outlet ports, and drive device.
The screw body consists of a head bearing, a tail bearing, a suspension bearing, a screw, a housing, a cover plate, and a base.
Drive device consists of motor, reducer, coupling and base.