Sinusoidal relationship between water flow rate and time
In order to raise the bed to the necessary height in the early stage of the rise, a strong rising flow rate is required, but at the same time, the same strong downward flow is caused, resulting in the bed being prematurely tight and shortening the effective sorting time. Reduce the processing capacity of the jig, and due to the strong suction, many low-density ore particles are mixed into the high-density product; due to the long time of the rising water flow, the adverse effect of particle size and shape on the stratification is also increased. 
Figure 1 Several typical jigging cycle characteristics used in industry (a) ua>ub, ta>tb; (b) ua>ub, ta=tb; (c) ua>ub,ta
(2) Jigging cycle characteristic curve with large rising water velocity and long acting time
The jigging cycle characteristic curve shown in Fig. 1(a).
The degree of asymmetry in the jigging cycle depends on the amount of water under the screen. During this jigging cycle, the loosening of the bed is beneficial to obtain a strong rising water flow, which improves the processing capacity of the jig. However, due to the long acting time of the rising water flow, it is not suitable for sorting materials of wide granularity and non-grading.
In coarse-grained metal ore sorting is often used such a jigging cycle. The jig may also be used to cycle through a preliminary sorting graded coal (0 · 5 a grain size 13mm).
(3) The jigging period in which the rising water velocity is greater than the falling water velocity but the acting time is equal
During the sinusoidal jigging cycle, the water flow is intermittently given to the submerged water, and the water flow characteristic curve as shown in Fig. 1(b) can be obtained.
The rising water flow of this jigging cycle is weaker than the rising water flow of Fig. 1(a); while the descending water flow reduces the flow velocity, the action time is extended relative to the figure (a), and the sucking effect is slightly enhanced. . Therefore, when processing a wide-grained fine-grained material, it is better than the above two jigging cycles. As China's tungsten, tin ore beneficiation plant process fine grade material jig jig has used this period.
(4) Asymmetric jigging cycle with large rising water velocity but short acting time
The asymmetric jigging cycle as shown in Figure 1(c).
During the intake air, the water flow is pushed by the compressed air and rises rapidly. Then the gas supply is interrupted and there is a short rest period when the water flow is only weaker due to inertia. When the compressed air is discharged, the water flow is reduced by its own weight, so that a descending water flow with a slow time and a long acting time is obtained.
With its treatment in the past domestic and desliming wide grain size or grade coal; foreign concentrator with it a few sorting iron, manganese and zinc ores some lead oxide. This kind of rising water flow is short and fast, and the hopping period is long and slow, and it is not suitable to deal with wide-grain or non-graded materials, whether it is loose, stratified or sucking.
(5) Asymmetric jigging cycle with slower rising water speed but longer duration of action
The rising water velocity is slow, resulting in a slower bed slack process. However, once the bed is loose, the ascending water flow gradually weakens and the shrinking process is slow, which not only prolongs the stratification time, but also during this period, the ore and water flow The relative movement speed between the two is also small, and the particle size and shape of the ore have a weak influence on the stratification by density, so it is advantageous for stratification.
Due to the slow process, the bed should not be too thick, and the processing capacity of the jig is low (6~10t per square meter). The descending water flow rate is fast and the action time is short. From the initial stage of decline, although it is not conducive to stratification by density, due to the slow flow rate and long time at the end of the ascending phase, many coarse and heavy materials have fallen back to the sieve plate. Therefore, participation in stratification activities at this stage is more Fine-grained granules, while the initial stage of decline is the main stage of sucking, so it is beneficial to sorting wide-grain or non-grading materials as a whole; the short-term and slow-speed of water flow is the favorable condition for sorting.
This jigging cycle (see Figure 1 (d)) is suitable for handling ungraded coal.
Practice has proved that the form of jigging cycle curve is one of the important factors to obtain good sorting effect. The reasonable jigging cycle curve should be adapted to the nature of the material selected, so that the bed is in a suitable loose state. The particles mainly move relative to the gravity acceleration difference. This is the basic principle for selecting the jigging cycle curve.
Product introduce:
In the machining process, the common methods of sheet cutting are manual cutting, semi-automatic cutting machine cutting and CNC cutting machine cutting. Manual cutting is flexible and convenient, but the quality of manual cutting is poor, the size error is large, the material waste is large, the subsequent processing workload is large, and the labor conditions are harsh and the production efficiency is low. Among the semi-automatic cutting machines, the profiling cutting machine has better quality of cutting workpieces. Because it uses a cutting die, it is not suitable for single piece, small batch and large workpiece cutting. Although other types of semi-automatic cutting machines reduce the labor intensity of workers, they have simple functions and are only suitable for cutting parts with relatively regular shapes. Compared with manual and semi-automatic cutting methods, CNC cutting can effectively improve the efficiency and quality of plate cutting, and reduce the labor intensity of operators. With the development of the modern machinery industry, the requirements for the work efficiency and product quality of plate cutting processing have also increased at the same time, so the market potential of CNC cutting machines is still very large, and the market prospects are relatively optimistic.
Working principle:
Usually, the CNC cutting system automatically processes the processed parts according to the pre-programmed processing program (the commonly used drawing software AUTOCAD). We put the machining process route of the part, process parameters, tool motion trajectory, displacement, cutting parameters (spindle revolutions, feed, back-feeding amount, etc.) and auxiliary functions (tool change, spindle forward rotation, reverse rotation, The cutting fluid is turned on and off, etc.), according to the instruction code and program format specified by the CNC cutting system, write a processing program list, and then record the content of the program list on the control medium (such as perforated paper tape, magnetic tape, disk, magnetic bubble, etc.). memory), and then input into the numerical control device of the numerical control machine tool, thereby directing the machine tool to process the parts.
This whole process from the analysis of the part drawing to the production of the control medium is called the compilation of the numerical control program. The difference between CNC cutting equipment and ordinary manual and semi-automatic cutting equipment in processing parts is that CNC cutting equipment automatically processes parts according to the program, while ordinary manual and semi-automatic cutting equipment needs to be operated by humans, we only need to change the control machine action. The program can achieve the purpose of machining different parts. Therefore, CNC cutting equipment is especially suitable for processing parts with small batches and complex shapes that require high precision!
Since the CNC cutting equipment needs to process parts according to the program, after the programmer has compiled the program, it is input into the CNC system to direct the machine tool work. Program input comes through the control medium. In this way, the CNC system is used to control the finished processing parts, and the graphics can be modified in time by the drawing staff, which can be used more freely, and the accuracy of the workpiece parts is also greatly improved compared with that of semi-automatic cutting equipment!
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