In order to improve the control accuracy and adjust the veneer thickness flexibly, the single chip microcomputer is used as the control system At last, the hardware and software design of the control system are introduced in detail. The result of the system running for a long time in the original log veneer veneer rotary cutter shows that the control system is stable and reliable. The accuracy of veneer thickness is up to ± 0.075 mm。
At present, in the production process of single board, the multi-layer board manufacturers use the traditional rotary cutting machine with centering round wood to process [1 μ 3], which has high precision and good quality. However, due to the existence of centering, when the diameter of rotary cutting round wood is about 200 mm, it cannot be processed on the rotary cutting machine with centering; Moreover, when the diameter of the round wood is small, the rigidity of the round wood is reduced, and the quality of the veneer is poor. If the remaining wood core is discarded or processed into the wood core wrench, it will cause a great waste of the raw materials, thus increasing the production cost of the veneer. Therefore, the manufacturer generally uses the non card round wood rotary cutter to re spin the remaining wood core, making full use of the raw materials.
At present, there are two main methods of turning round wood with non card veneer cutter: (1) manual visual inspection of veneer thickness, through the speed regulation of the cutter feeding motor to control the cutter feeding amount, this control method is relatively backward, which can not guarantee the uniformity of veneer thickness; (2) fixed gap and Constant pressure drives the veneer cutter to control the veneer thickness. However, due to the great difference in the hardness of the logs, the uniform veneer thickness can not be effectively guaranteed by constant pressure and the clearance between the cutting edges.
Therefore, the single chip microcomputer control system is used to overcome the defects of backward control methods and improve the thickness uniformity of veneer.
The working principle of no card rotary cutter.
The schematic diagram of the working principle of the non card rotary cutting machine is shown in Figure 1. The log rotates under the common drive of two rotating center fixed rolls and one rotating center moving rolls, The center support of the rotary cutter and the rotary cutter are relatively fixed and move together, so that the rotary cutter will plane out the thin plate from the log, and the thickness of the single plate is controlled by the clearance between the rotary cutter and the rotary cutter and the moving speed of the rotary cutter The gap of the cutting edge is relatively fixed. It is adjusted by the gap adjustment device of the machine tool, which depends on the thickness of the plate to be rotated. The moving speed of the rotary cutting tool controls the rotating speed of the driving motor through the control system. Therefore, the moving speed of the rotary cutting tool indirectly determines the thickness of the single plate. From Figure 1, it can be seen that It can be seen that the rotation speed of the driving roller is constant, that is, the rotation linear speed of the log is constant. With the change of the log diameter, the angular speed of the log changes, that is, the time required for the log to rotate for a circle also changes. Therefore, the movement speed of the rotary cutter is a variable value, which is a non-linear relationship
When the circuit works, there are three signals: timer pulse signal source provided by timing pulse, clear signal reset timer, reset signal (generate system reset). When it works, it is assumed that the software cycle period is 7%. If the timer timing length is set to tat'ct,,, the CPU will The timer will be reset once in every working cycle. As long as the system works normally, the timer will not overflow and the system will not be reset. Otherwise, when the system fails, the CPU cannot clear the timer in time, the timer will overflow and X25045 will pass the reset signal In response, X25045 also has a significant feature, that is, its internal memory (512x8) E2PROM, in this system can save the parameter values set by the system, so as to ensure the normal use of data and not lost due to power failure
2.6 position switch and keyboard input circuit
The control mode of the system is to control the rotation speed of the variable frequency motor by judging the position of the rotary cutter, so the position signal is indispensable. The position sensor selects the travel switch, which is set with four, It is respectively set at the starting point of the rotary cutter and 250, 100 and 50 mm where the rotary cutter passes. When the "start" button is pressed, the rotary cutter moves quickly to 250 mm, and then feeds at the feed rate set by the system; when the round wood is processed to the diameter of 100 or 50 mm, whether there is deviation in the processing is detected by software programming (check the control word working table), and corresponding positions are made Ensure the machining accuracy
In addition, for the convenience of control, the touch panel is designed, which uses four keys an 4 to realize the function setting. The functions of the four keys are start, fast back, stop and selection (board thickness). The closed key number on the keyboard is judged through the P2 port of AT89C51. When any key is pressed, the connected input data line is "1", otherwise it is "0" Once a key is pressed, the program processes accordingly
2. / system immunity + disturbance design
Because there are many high-power inductive loads in the industrial field, there will be interference caused by power supply such as overvoltage, undervoltage, voltage surge and peak voltage. In order to prevent interference from entering the single-chip microcomputer system, photoelectric isolation technology is used in the input and output signal channels, tlp521 photoelectric isolation device is selected The specific circuit design principles are: (1) the output and the input data are in the same phase, i.e. when the output terminal is high level (output terminal = 1), the input terminal shall also be high level, and vice versa; (2) the power consumption of the system shall be minimized, i.e. when the system is not working or in the monitoring state, photoelectric