本文对传统电位器计算预驱卷径与新型编码器计算预驱卷径两种计算方法给以分析，并对其优劣性进行比较。 Abstract: This paper analyzes the two calculation methods for calculating the pre-drive coil diameter of a traditional potentiometer and the pre-drive coil diameter of a new type of encoder, and compares their advantages and disadvantages. The encoder calculates the pre-drive coil diameter, which can reduce the debugging coil diameter time and improve work efficiency. Although the new encoder of the printing press calculates the pre-drive roll diameter, the hardware cost is slightly higher than the traditional calculation method, but in actual use, it can meet the common needs of both the manufacturer and the enterprise.
With the increase of cost awareness of enterprises and the need for benefits, the rejection rate of printing presses in the high-speed receiving process has attracted more and more attention from enterprises. During the splicing process, the accuracy of the diameter calculation of the pre-drive new rolls has a great impact on the stability of the tension after the splicing is completed and the loss of cutting waste. In view of this problem, this article will summarize the two calculation methods of the traditional potentiometer to calculate the pre-drive coil diameter and the new encoder to calculate the pre-drive coil diameter, and compare their advantages and disadvantages.
First, the principle of potentiometer calculation of pre-drive coil diameter
Connect the voltage required by the PLC analog input module at both ends of the pre-drive coil diameter detection potentiometer, and the center tap of the potentiometer is connected to the PLC analog input channel (as shown in Figure 1).
Install the potentiometer on the unloading turret, so that the voltage at the two ends of the potentiometer's center tap changes with the rotation of the turret. At this time, the analog quantity detected by the PLC is changing.
During the debugging process, it is necessary to measure the detection value of the potentiometer at each node of the winding diameter segment (D1 to D4 in Figure 2) (X1 to X4 in Figure 2). ), Write to the PLC through the man-machine interface. During use, the feedback value of the potentiometer at that time (X 0 in Fig. 2) was detected, and the pre-drive coil diameter was calculated by a programmed program in the PLC (D 0 in Fig. 2).
When using traditional potentiometers to calculate the pre-drive coil diameter, the following problems exist:
、由于电位器本身是一个滑动变阻器，其阻值的分布无法保证十分平均，因此在计算预驱卷径的过程中，要在最小和最大工作卷径之间分若干段，以保证计算出的预驱卷径的准确。 1. Since the potentiometer itself is a sliding rheostat, the distribution of its resistance cannot be guaranteed to be very even, so in the process of calculating the pre-drive coil diameter, it is necessary to divide into several sections between the minimum and maximum working coil diameter to ensure the calculation. The diameter of the pre-drive coil is accurate. Because it is divided into several sections, during the debugging process, it is necessary to record the voltage value when the potentiometer is at each section node. So as many nodes as there are, how many templates are needed to perform analog material receiving to detect the voltage value of each node of the potentiometer. In actual operation, it is time-consuming and labor-intensive.
、在实际使用过程中，由于维修人员的误操作或其他原因触碰到电位器，造成电位器跑动，就会直接影响预驱时计算卷径的精度，进而影响到高速接料是否能够成功。 2. In the actual use process, due to the misoperation of maintenance personnel or other reasons, the potentiometer is touched, causing the potentiometer to run, which will directly affect the accuracy of the calculation of the roll diameter during pre-drive, and then affect whether high-speed material receiving success.
、如果检测预驱卷径的电位器损坏，更换新的电位器后，就需要重新对卷径进行调试。 3. If the potentiometer that detects the pre-drive roll diameter is damaged, you need to re-adjust the roll diameter after replacing the new potentiometer. In printing companies, there are few templates required for debugging the scroll path, which makes re-commissioning a difficult task.
Second, the principle of the encoder to calculate the pre-drive coil diameter
Select the encoder, and connect the matching power supply to the encoder's power line, and the encoder A and B phases are respectively connected to the PLC high-speed counting unit (as shown in Figure 3).
The encoder is installed on the unloading turret, so that the high-speed counting unit can detect pulses as the turret rotates. The specific debugging methods are as follows:
、测量从回转架的中心到一个放料轴中心的距离，并把此值通过人机界面写入PLC，以供计算使用（图四中L）。 1. Measure the distance from the center of the turret to the center of a discharge shaft, and write this value into the PLC through the man-machine interface for calculation (L in Figure 4).
、确定基准位：压下裁切大臂，使大臂处于裁切位置；转动回转架，使放料轴中心与大臂上的检测光电开关在同一水平线上，此位置即为基准位。 2. Determine the reference position: press down the cutting arm to make the arm at the cutting position; turn the rotary frame so that the center of the discharge shaft and the detection photoelectric switch on the arm are on the same horizontal line, this position is the reference position. At this time, the sensor can be installed and fixed on the turret in order to detect the reference position in the later use.
Working principle: The equipment is in the running state, and the old rolls are almost finished, and the new rolls are in place (see Figure 5). According to the pre-loading, when the turret is rotated to the reference position of the old roll, the encoder signal detected by the PLC is cleared and counting is started again. The turret continues to rotate, and the cutting boom is depressed. When the photoelectric detection switch on the cutting boom detects a new roll, the turret is stopped (as shown in Figure 4). At this time, the PLC detects that the encoder pulse number is P 0 . The angle Θ shown in Figure 4 can be calculated based on the pulse number P of the selected encoder and the gear ratio i between the encoder and the turret. According to the angle Θ and L in Figure 4, we can calculate the pre-drive new roll radius R that we need, and finally get the precise new roll diameter to ensure the pre-drive accuracy.
In the above working principle, the following formula can be used for calculation:
Θ = [180－ (360 × P 0 ) ÷ (P × i)] ÷ 2
×L×sinΘ R = 2 × L × sinΘ
The encoder is used to calculate the pre-drive coil diameter. Because the encoder signal must enter the PLC's high-speed counting unit, the hardware cost is slightly higher than the potentiometer to calculate the pre-drive coil diameter, but it has the following advantages:
、由于计算方法与实用电位器计算方法不同，因此在调试卷径过程中，只需要定一个基准位，并在人机界面上输入一个计算用尺寸即可。 1. As the calculation method is different from the practical potentiometer calculation method, in the process of debugging the coil diameter, only a reference position needs to be set, and a calculation size can be entered on the man-machine interface. It greatly reduces the time for debugging the coil diameter and improves the work efficiency.
、在实际使用过程中，维修人员的误操作或其他原因触碰到电位器不会影响预驱时计算卷径的精度。 2. In the actual use process, the incorrect operation of the maintenance personnel or touching the potentiometer for other reasons will not affect the accuracy of the calculation of the roll diameter during pre-drive.
、当检测预驱卷径的编码器损坏时，只需要重新安装好新的编码器即可使用。 3. When the encoder of the pre-drive roll diameter is detected to be damaged, you only need to re-install the new encoder and use it.
Third, the conclusion In today's increasingly fierce market competition, all walks of life are looking for new methods with high performance and low cost to win market share. Although the method for calculating the pre-drive roll diameter of the new encoder of the printing press described in this paper may be slightly higher than the traditional calculation method, in actual use, it can meet the common needs of both manufacturers and enterprises. For the manufacturer, the failure rate is reduced and the commissioning work is simple and easy. It not only reduces the maintenance difficulty, but also reduces the warranty service fee, which greatly improves the work efficiency. For the printing company, the new method improves the printing machine. Performance and stability, reduce waste loss rate, and ensure the economic benefits of the enterprise.