Application of Single Chip Microcomputer in Gold Foil Positioning System

　　This article introduces how a single chip microcomputer controls a servo motor to achieve positioning control of gold foil in a die-cutting and hot stamping machine control system. It has functions such as setting, display, and control.

　　1 Overview

　　Hot stamping is the process of melting the adhesive by heating and hot stamping metal foil or color chips onto the surface of paper or other materials to create a special decorative effect.

　　With the improvement of material and cultural living standards, people's requirements for packaging and decorative materials are getting higher and higher. Only by introducing computer control into the control system of die-cutting and hot stamping machines can the production efficiency and product quality of die-cutting and hot stamping machines be improved. There are two situations in hot stamping, as shown in Figure 1. One is that the area to be hot stamped is a continuous hot stamping area as shown in the left figure in Figure 1. At this time, it is necessary to control the gold foil to move one step, the hot stamping heating template to move once, then move again, and move again, and repeat continuously to complete the hot stamping work of batch printed products. The second is that the hot stamping area is two or more discontinuous hot stamping areas as shown in the right figure in the following figure. If the first solution is still used, the gold foil in the middle area will be wasted. For this reason, the gold foil is taken a small step, the hot stamping heating template moves once, then takes a small step, and then hot stamps. At this time, the gold foil of the following part has been hot stamped, so it is necessary to take a big step, cross these gold foils and then hot stamp, in order to meet the hot stamping requirements of the printed products, and repeat this process continuously to complete the batch hot stamping of such printed products, which avoids the waste of gold foil. We call a small step the walking amount (X), a big step the skipping amount (Y), and the number of small steps followed by a big step is called the walking number. The value depends on the size of the unstamped area in the middle, which is set by the user according to the requirements of the hot stamping layout. In the past, the above control was mostly mechanical, with a complex system structure, poor positioning accuracy, and high cost. In order to make up for these shortcomings and make the die-cutting hot stamping machine run reliably, efficiently, and stably, this system adopts the following control scheme:

　　(1) Use a servo motor to control the accurate start and stop of the gold foil's movement and skipping steps.

　　(2) The system has a display function: it can display the running amount, skipping amount and running number of the current printed product.

　　(3) The system has keyboard management function: the walking amount, skipping amount, walking number, run/set number switching, system reset and other controls can be set through the keyboard.

　　(4) The system has anti-interference ability.

　　2. System composition

　　2.1 Hardware Composition

　　In order to achieve the above requirements, the system uses 89C51 microcontroller, MC1413 driver, 74LS154 decoder, and LED display to form the entire control system. The system block diagram is shown in the figure below.

　　2.1.1 89C51 MCU

　　AT89C51 is an 8-bit microcontroller with 4K bytes of flash programmable and erasable read-only memory . It provides a flexible and inexpensive control solution for many embedded control systems.

　　2.1.2 Display interface technology

　　In the case of multi-digit LED display, in order to simplify the hardware circuit , a multiplexing of the segment selection line is formed by an 8-bit I/O (Po port). The common cathode or common anode of each digit is controlled by the corresponding I/O (P2 port) to realize the time-sharing selection of each digit.

　　2.1.3 Keyboard

　　This system has 5 buttons, plus 1 button ①, minus 1 button ②, system reset button ③, run/set switch button ④, and confirm button ⑤.

　　2.1.4 Anti-interference

　　The system adopts the photoelectric isolation method to allow the external proximity switch signal (imprinting signal) to enter the I/O port of the microcontroller through photoelectric isolation. The system software detects this signal and controls the walking and skipping steps.

　　2.1.5 Servo motor and its drive

　　The AC servo drive system uses power electronic control technology - intelligent power module (IPM) and hybrid integrated circuits . Its unique circuit design can obtain satisfactory dynamic and static performance. It is matched with AC servo motors and has the characteristics of wide frequency band, fast response speed, wide speed regulation range, high AC efficiency, no noise, no brushes, and maintenance-free. AC servo motors have small inertia, small size, and high positioning accuracy. AC servo systems will become more and more popular in the field of high-performance servo drives. The principle block diagram of the servo positioning system is shown in the figure below.

　　2.2 Software Composition

　　In order to meet the technological requirements of the die-cutting and hot stamping machine control system, the system's main program, interrupt service program, and display program software block diagram are shown in the figure below.

　　The entire control system uses AC servo motors to control walking and skipping steps, so that the positioning control meets the process requirements, the production cost is reduced, the operation is reliable, the positioning is accurate, and the efficiency is improved.