Four manufacturing factors that affect the reliability of large vibrating screen are attached to the operation steps of the whole machine assembly
For a long time, the domestic large-scale vibration screen is generally premature failure, poor reliability problems, to the production and enterprises bring a lot of losses. Compared with imported original equipment and domestic equipment, it is found that manufacturing process and process play an important role in product quality.
Large vibrating screen structure
Before understanding the manufacturing process of vibrating screen, we still need to have a certain understanding of its structure!
Common large vibration screen (generally refers to the screen surface area is not less than 20 square meters of vibration screen), including linear screen, banana screen, high frequency screen, circular vibration screen, these vibration screen generally mainly by the screen box, screen surface, vibrator, transmission device, vibration isolation device.
Under vibrator excitation, circular, elliptic or linear vibration is generated between screen box and screen surface, which makes materials loose and move up and down regularly on screen surface, so as to achieve the purpose of material classification, dehydration and disintermedium.
The following parts processing and machine assembly process to do a brief introduction!
1. Side plate processing
The side plate has a large area and irregular shape. According to the requirements of vibration force, the main side plate is not allowed to be splicing, but the whole steel plate shall be cut.
When the traditional flame cutting machine is adopted, the steel plate will be deformed by heat, which will affect the shape and size tolerance of the side plate, and the appearance will be affected by the large incision roughness.
Using CNC plasma cutting machine can avoid this problem, and before blanking can be through shaping measures leveling steel plate, can prevent the steel plate has many defects, blanking effect is better.
In order to ensure the symmetry of the side plate, the side plate, the reinforcing plate connected with the side plate and the reinforcing Angle steel can be stacked and welded after spot welding. Due to the influence of human factors, it is difficult to guarantee the marking precision. And the use of plane CNC drilling can achieve a clamping, at the same time drilling out of all the pieces of the hole, the work efficiency and operational accuracy is greatly improved. For the side plate with splint exciter, the mounting hole of bearing seat needs to be machined through boring machine, and then the side plate is disassembled and welding spots are polished.
2, beam processing
Screen beam is connected between the two sides of the plate, a large number of, usually large vibration screen beam length of 3.60m above. The screen beam of general large vibrating screen includes drive beam, beam and reinforcing beam, among which drive beam is the main body of bearing box type vibration exciter, the welding is relatively complex; The beam and reinforcing beam have the function of connecting and bearing the sieve plate, which are the key parts that are easy to break and damage.
In order to improve the reliability of large vibrating screen, the quality of screen beam, including shape and position tolerance and dimension tolerance, should be guaranteed in both welding and machining aspects, and flaw detection should be done after welding.
3. Processing of vibration exciter
According to the different ways of vibration excitation, the vibration exciter of large vibration screen is divided into box type vibration exciter and splint type vibration exciter. At present, the use of box - type exciter in the majority.
(1) box type vibrator
The main components of box exciter are box and gear, and the casting level of box is uneven in China. Some casting factories adopt resin sand casting molding process, which can produce the precision casting box that meets the requirements, and the casting processing quantity is significantly reduced, and the appearance quality is significantly improved.
The box body adopts horizontal boring and milling machining center for integrated processing, which can realize all machining and forming in a single clamping and ensure the machining accuracy. If there is no such equipment, you can use the coordinate boring machine supplemented by marking to machining, which can basically ensure the processing quality of the box. It is necessary to pay attention to the influence of high frequency quenching on inner hole tolerance in gear processing.
(2) splint type vibration exciter
The main components of splint type vibration exciter include bearing seat, shaft and eccentric block, etc. Generally, the tolerance range of inner hole of bearing seat is determined according to the transition fit, and the excess tolerance is likely to cause the failure of bearing temperature or bearing "ring", which will affect the reliability of vibration screen.
If out of tolerance problem, can use brush plating and grinding and other measures to remedy. Usually eccentric block shape requirements are not high, can be used for machining; For its inner keyway, the machining quality can be improved by wire cutting. The order of machining is the keyway first and then the shape. When machining the shape, the keyway is used as the reference to improve the final quality of the eccentric block.
4. Complete machine assembly
The whole machine assembly is the process of assembling qualified parts and components and purchased qualified standard parts. The research found that: even if all the parts are qualified, the difference of assembly process has a great impact on the reliability of the whole machine. If the assembly is not proper, the equipment is prone to swing, noise, abnormal temperature and other phenomena, and even the bolt is damaged by shear.
The common assembly method has the traditional whole machine assembly and the special tooling assembly, here we introduce the former.
Traditional assembly steps:
When the screen body is assembled by traditional assembly process, the side plate, internal and external reinforcing plate and reinforcing Angle steel should be assembled together first. Before assembly, the burr should be removed by grinding. No sundry matter should be allowed between the contact surfaces.
The specific approach is:
First, place the side plate on one side horizontally, assemble the beam, reinforcing beam and inputting beam vertically, and then assemble the side plate and supporting beam on the other side to form the sieve box frame. The diagonal between any two beams shall be detected when assembling the beam. If the difference is too large, the order of each beam shall be adjusted in time. In addition, do not tighten the bolt, to be tightened later.
Put the screen box flat on the vibration platform, adopt four supports of the same height to install the two ends of the beam with the supporting head, make the two side plates hang down naturally, and lower along the same horizontal plane. Take the processed bolt hole of the side plate as the reference, measure the diagonal size of the screen box, and control the error within 2mm, tighten the bolt after adjusting. In the process of tightening bolts, it is necessary to operate from the middle of the screen box to both ends, and tighten the bolts at both ends of the side plates after the bolts in the middle of both sides are tightened, so as to avoid cumulative errors.
Next, we need to install the sieve board and press the sieve surface. The shaker can be assembled in parallel with the screen box. When assembling the splint shaker, the outer ring and inner sleeve of the bearing should be used in accordance with the mark, and the axial clearance between the bearing gland and the bearing should meet the requirements. Before installing eccentric blocks, weigh them separately and then use them in pairs according to the quality conditions to ensure the same excitation force on both sides. After assembling the exciter, level the foundation with horizontal instrument, and then install the support spring with the same stiffness in the symmetrical position to ensure that the upper and lower supports are parallel to the spring contact surface. Finally, the drive motor and other components are connected with the sieve body, and the assembly of the whole machine is completed.
To improve the reliability of large vibrating screen, it is necessary to study systematically and deeply from the aspects of design, manufacture, use and maintenance. Advanced manufacturing technology is the basic guarantee to produce high-quality products and improve economic benefits. Only by improving the manufacturing technology level, can the domestic large-scale vibrating screen better adapt to the fierce competition at home and abroad, and have a good market reputation.