In view of the defects of the existing protection device mineral sizers, a new integrated protection device is designed. Emphasis is placed on the optimization of the protection design of the gear coupling, the hydraulic coupler and the electrical system. The structure of the protective device is simple and it can be used extensively to modify mineral sizers. Practical application shows that the improved mineral sizers can provide effective protection for the crusher, improve the performance of the crusher in harsh working conditions and further enhance the efficiency of mining and beneficiation operations.
The traditional dental coupling The traditional dental coupling is a vulnerable component on the powerful mineral sizers. Due to the need for frequent replacement, the less expensive dental couplings in traditional crusher drive system designs are often less sophisticated.
Strong mineral sizers of the coupling have large side tooth clearance, allowing a certain angular displacement in operation. As the crusher needs to cope with low-speed and heavy-load conditions in coal crushing operation, the internal and external tooth surfaces of the gear coupling need to engage with each other periodically. The bearing capacity of the tooth surfaces is large, so good lubrication and sealing must be maintained. In the design, the tooth roller connected by the gear coupling and the reducer of two axes, is the tooth roller and the reducer to keep synchronous rotation, and output torque. Due to the influence of installation error, operation wear deformation and foundation settlement and other factors, tooth roller and reducer two axes will produce a certain degree of relative displacement, it is difficult to strictly maintain the alignment, but in the traditional design does not take into account the impact of such displacement on the gear coupling, resulting in the coupling can not be timely release when the failure of teeth, can not play the due role of deceleration protection.
(2) Hydraulic coupler The hydraulic coupler is the key hydraulic transmission component on mineral sizers. It can optimize the match between the prime mover and the working machine, improve the motor's power factor and starting efficiency, reduce vibration, shock and torque, prevent overload, and effectively protect the motor and the reducer. The hydraulic coupler is installed between the motor and the reducer, which can be regarded as a combination of turbine and centrifugal pump. Its main body is composed of turbine, pump wheel, auxiliary chamber, input shaft, output shaft, housing and safety protection device. The two ends of the input shaft of the hydraulic coupler are connected to the motor and the reducer respectively. The input shaft realizes power distribution by changing the velocity of the transmission medium in the gearbox of the reducer. At the same time, the increase of torque can be limited by reducing the transmission fluid in the gearbox of the coupler. When overload or stuck fault occurs in the crushing process, the hydraulic coupler can disconnect the transmission system by increasing the transmission medium release in the cavity and increasing the working pressure to implement protection. But the actual application shows that when large pieces of iron debris fall into the crushing chamber, because of the slow response speed of the hydraulic coupler, it is easy to occur the gear failure of the reducer, and even lead to the abandonment of the equipment.
(3) Electrical system The electrical control system of crusher is mainly composed of PLC controller, speed sensor, integrated display screen, control button, alarm and power supply. Among them, the speed sensor is fixed in the crusher's gear coupling cross arm front segment, PLC controller, working instrument and voltage regulator power supply installed in the control box, comprehensive display screen, control button and signal lamp installed in the control box panel. When coal and gangue are broken, the motor speed signal collected by the velocity sensor is sent to the PLC controller. When overload occurs, the controller will give a warning signal in time, and the operation will be stopped automatically. After the fault is removed and the equipment self-check is normal, the alarm will be lifted and the crusher can start up again. When jammed fault occurs, PLC controller issued instructions to make the motor automatically reverse, so that the clogged material loose. In practical application, when large pieces of iron are mixed into the crushing chamber, toothing fault will occur instantaneously. Because there is a delay in signal acquisition and transmission of the velocity sensor, the fault signal is fed back to the controller, and then the fault type is judged, the alarm is given and the corresponding protection reaction is made, the above feedback link takes 4~7s, leading to a certain lag in the protection of the breaker electrical system. The protection effect of the transmission system is not very ideal.
Through the analysis of the structure and working mechanism of the main mineral sizers transmission mechanism, it is found that the protection effect of the existing protective device design needs to be improved. The dental coupling is the core part of mineral sizers protection device. In this study, the design defects of the dental coupling have been optimized.
(1) The optimized mineral sizers dental coupling is composed of two inner ring (with inner teeth and flanges) and outer sleeve (with outer teeth meshing with inner teeth). The two inner gear rings are connected by bolts, while the two outer gear bushings are connected with the input and output shafts respectively. The gear coupling relies on the meshing motion of the inner and outer teeth to transfer torque. When the load of the coupling exceeds the allowable torque, the fixed bolt of the inner gear ring will be automatically cut, so as to realize the protection of the reducer. In order to ensure proper clearance after internal and external teeth meshing, the top of the external teeth of the gear coupling is designed to be ellipsoid. This design leads to the inevitable radial displacement, axial displacement and angular displacement of the inner gear ring during transmission, which will aggravate equipment wear, so it is necessary to maintain sufficient lubrication of the tooth surface. (2) Determination of Main Operating parameters The improved mineral sizers employ the YB2-315S-2 explosion-proof motor, speed n=1520dmin, rated power =110kW, power factor =0.84, efficiency =93.7%. When the coal is passed through normally, the working current of the motor 1=50~55A; When large gangue, coal rock and so on through the crusher, the working current is 100-120A.
A comprehensive protection strategy has been adopted in our design. The strong mineral sizers have been upgraded by optimizing the dental coupling, hydraulic coupler, and electrical system in mineral sizers. The operation has shown that the improved mineral sizers can not only provide effective protection to the crusher but also improve the efficiency of mining and beneficiation operations: Moreover, when the unbreakable object enters the crushing chamber, the two M30 ream bolts installed on the gear coupling will be forced to cut instantaneously to avoid overload and tooth failure, providing reliable protection for the drive motor and the gear of the reduction box. The design can be widely used in the upgrading of various mineral sizers. It can meet the requirements of mining operations for the comprehensive performance of the crusher. It can help enterprises to save costs and increase efficiency, improve production efficiency and product quality.
