1. Anti-mite machine actuator
The axial movement of the weldment on the roller frame, the weldment itself is in a spiral motion, if measures can be taken, the left-hand rotation of the welding roller frame weldment is changed to right-handed or right-handed to left-handed until The weldment is no longer spiraled.
Currently, there are three types of actuators that can accomplish this task:
(1) jack-up actuator
The roller on one side of the driven roller frame can be lifted and moved to offset the axis of the weldment, and at the same time, the axial component of the weldment is changed by its own weight. The advantage of this adjustment method is that the adjustment sensitivity is high, and the disadvantage is that the manufacturing cost is high and the volume is large.
(2) Offset actuator
The rollers on both sides of the driven roller frame can be offset in the same direction along the vertical center line, thereby changing the axial friction component of the roller and the weldment. This adjustment method has the advantage of high sensitivity, but the biggest disadvantage is that the wear of the roller is too large.
(3) Translational actuator
The rollers on both sides of the driven roller frame can be horizontally moved perpendicularly to the axis of the weldment at the same time, thereby achieving the purpose of adjusting the axis of the weldment and adjusting the angle of the axis of the roller. This adjustment method has the advantages of good stability, low manufacturing cost, simple structure and no additional installation space.
2, the drive wheel speed control
In order to achieve smooth rotation of the weldment stepless speed regulation, two driving modes are generally adopted: DC speed regulation and AC frequency conversion speed regulation. Since the DC speed regulation has the defects of high failure rate and high cost, AC frequency conversion speed regulation is selected. With the development of electronic technology, AC variable frequency speed regulation has been able to fully meet the needs of various tonnage welding roller frames.
In order to make the roller pitch adjustment of the welding roller frame convenient and reliable, and the combination is convenient, it is recommended to adopt the design scheme of the driving wheel single driving, that is, each driving wheel is driven by a single motor and a speed reducing mechanism. However, it is necessary to pay attention to the synchronization problem of each driving wheel. In the selection of the structure of the motor and the reducer, it is necessary to select the characteristics with consistent characteristics and measured. It is recommended to use a set of drive sources in the drive mode, and each drive wheel motor is connected in parallel.
3. Detection of axial movement of weldment
The purpose of detecting the axial movement of the weldment is to detect the turbulent displacement of the weldment in the axial direction. In principle, it can be taken on the side of the weldment wall and the end face of the weldment. The side detection method of the tube wall can be free from the influence of the end face error of the weldment. However, this detection method is necessary to remove the vertical rotation component of the cylinder wall, plus the effect of slippage, rough surface of the cylinder and dirt, so that it is reliable. The coming of the sensor is not easy. The detection method of the end face of the weldment is a commonly used inspection method. This kind of detection is inevitably affected by the unevenness of the end face of the welded weldment in the vertical direction of the axial line. Therefore, it is required to process the end face of the weldment. However, for large weldments, the higher the accuracy of such machining requirements, the greater the difficulty and expense. Whether it is possible to reduce the requirements for end face processing is important. For example, the process requires that the axial turbulence of the weldment is not more than ± 2 mm, but the unevenness of the measured end face of the weldment is greater than ± 2 mm. Under such conditions, whether the axial turbulence of the weldment can be prevented is a measure of prevention. One of the important indicators of whether the roller frame is practical.
4, Fuzzy control
For a weldment, especially for a large weldment, it is difficult to know exactly the perpendicularity and unevenness of the test end face relative to its axis. It is sometimes unrealistic to stipulate that the end face machining error does not exceed a certain value. Under such conditions, how to achieve the purpose of preventing smashing of different weldments, even zero turbulence, is the key.
For the control system like the anti-roll roller frame, in the case of many uncertain factors affecting the axial movement of the weldment, the means of fuzzy control can be used to achieve the control purpose. Fuzzy control is the use of computer to simulate people’s thinking, according to the rules of human operation, that is, the use of computers to achieve human control experience. Fuzzy mathematics can be used to describe fuzzy concepts such as process variables and control effects and their relationship. According to these fuzzy relations and the detection values of process variables at each moment, the fuzzy control is used to obtain the control amount at that moment. . Fuzzification and precise control are dialectical relationships. Computers follow the human mind for fuzzy control, while human brain’s heavy control experience is a fuzzy control rule composed of fuzzy conditional statements. Therefore, it is necessary to convert the input signal from an accurate amount to a fuzzy amount. The fuzzification first converts the sampled value of the input signal to a point on the corresponding domain (range transform) and then transforms it into a fuzzy subset on the universe. Contrary to fuzzification, the defuzzification process transforms the fuzzy control effect obtained in the inference process into an accurate control quantity.
Welding roller frame
Welding roller frame
However, for a control system in which the detected end face error of the controlled weldment is greater than the anti-cracking accuracy, it is obviously not sufficient to solve the problem by using the fuzzy cybernetic method to achieve the purpose of preventing the weldment. Because the end face error of the weldment is greater than the requirements of the anti-cracking accuracy, whether the offset sent by the sensor is caused by the error of the end face of the weldment or due to the axial movement of the weldment, the computer only sends it. The signal is indistinguishable, and the error size and shape of different weldments are different.
5, Adaptive control
Adaptive control has the ability to modify its own characteristic parameters to accommodate changes in the dynamic characteristics of the controlled object and disturbance. In adaptive systems, the algorithm we use is the “parameter tracking algorithm.” That is, the computer automatically tracks and presets the threshold of the sent signal, and these parameters are not fixed during the control process. To put it bluntly, let the computer remember the shape of the end face of the weldment and then distinguish the true amount of turbulence. In this way, the problem is simple, as long as the control of the momentum is controlled and the end face error is ignored. Following this idea, after a period of adjustment, the “zero turbulence” of the weldment in its axial direction can be achieved. The length of the adaptive process depends on the end face error of the weldment. For a weldment with an end face error of 5 mm, the amount of turbulence can be limited to within ±2 mm after about 15 minutes, and the weldment can be maintained after about 0.5 h. “Zero sway”.