Abstract: Based on the requirements of US toy safety standards to determine the main axis direction and dimensions of toys, and to calculate the burning length and speed of toys along the main axis direction, this paper discusses in detail the working principle, working process, hardware structure, software program and technical characteristics of a toy combustion tester, combining PLC control technology, high-performance micro-drive device and stepper motor working principle. It points out that this tester can meet the US toy combustion testing requirements. Keywords: Automatic Control; PLC; Flammability Testing; Toy Safety Testing Abstract: Based on the requirements of ascertaining the orientation and dimension of a toy's major axis, this paper calculates the flammability dimension and speed along with the toy's major axis in the American standard consumer safety specification for toy safety. It combines PLC control technology, a high-performance and fine-segmentation driver, and a step-in motor. It demonstrates the tester's working principle, hardware construction, software programming, function, and technological characteristics. It points out that the tester can meet the testing requirements of the American standard toy safety. Keywords: Automation Control; PLC; Flammability Testing; Toy Safety Testing 1 Introduction In the American toy standard ASTM F963-03, the toy's main axis is defined as: the longest straight line connecting the farthest parts or endpoints of the product. A product can have more than one main axis, but their lengths must be equal. Determining the direction and dimensions of the toy's main axis is often very time-consuming when conducting overall flammability testing on plastic and plush toys. Currently, the direction, size, and burning size of a toy's main axis are determined by human eyes and a steel ruler. However, the toy's shape differs significantly before and after burning, making it impossible to accurately measure the burning size with the naked eye. This results in test results being significantly influenced by human factors, leading to low efficiency, large errors, and poor repeatability, severely impacting the determination of whether a toy passes the flammability test. With the development of computer control technology, PLCs (Programmable Logic Controllers), with their modular structure, highly anti-interference I/O processing components, flexible hardware configuration, scalability, and stability, provide a stable platform for applications in various locations and are widely used in the field of automatic control devices. This automatic toy combustion tester adopts advanced PLC control technology and high-performance subdivision drive control technology, meeting the requirements of relevant clauses in the American toy standard ASTM F963-03. It automatically measures the toy's main axis size, automatically records the burning time, and calculates the burning speed, with high accuracy, high efficiency, and good stability, ensuring the safety testing of toys. 2. Working Process The automatic combustion tester has a platform structure, consisting of four parts: a human-machine interface, a control unit, a drive unit, and a support and positioning unit, as shown in Figure 1. [align=center]Figure 1. Composition Diagram of the Automatic Combustion Tester[/align] Human-Machine Interface: Utilizes the F920 operating panel from Mitsubishi Corporation of Japan. Various operation functions can be set via operation buttons, and test parameters and results can be displayed on the screen. Operation is simple and convenient, with timely and accurate display. Control Section: The controller uses the FX1S-10MT PLC from Mitsubishi Corporation of Japan, featuring high precision, high speed, and reliable stability. Its main function is to receive input information, perform judgment and data processing based on the information, and then output control signals to the drive section of the tester. It also has a timing function. Drive Section: Includes three stepper motors, using the advanced JQF-MD808 stepper motor driver from WJT (USA). It receives pulse output signals, controls the rotation angle and direction of the stepper motors, and completes various driving tasks during the testing process. Support and Positioning Section: The mechanical part of the automatic tester, mainly composed of a base, support rod, positioning rod, scale, etc. The mechanical structure diagram of the automatic toy combustion tester is shown in Figure 2: [align=center] 1. Motor 1 2. Lead screw 3. Scale mark 4. Motor 2 5. Lead screw 6. Movable block 7. Support rod 8. Base 9. Fine adjustment platform 10. Bearing 11. Positioning rod 12. Bushing 13. Rotating shaft 14. Motor 3 Figure 2 Mechanical structure diagram of automatic combustion tester[/align] Its working process is as follows: (1) Determine the direction of the main axis of the sample: The toy sample is placed on the rotatable worktable. The stepper motor drives the support rod to rotate, which drives the positioning rod on the support rod to be consistent with the direction of the main axis of the toy. By finely adjusting the direction and position of the rotating worktable and the positioning rod, the direction of the main axis of the sample is determined. (2) Accurately measure the main axis dimension and burning dimension of the sample: Use a stepper motor to drive the scale on the lead screw to move from one end of the toy's main axis to the other end. The distance moved is the main axis dimension of the toy. Move the positioning rod away, ignite the toy for testing, and after the flame goes out, move the positioning rod back to the initial position before ignition. At this time, the direction of the positioning rod is consistent with the direction of the toy's main axis. This position is ensured by the stepper motor controlled by the PLC. Move the scale from one end of the toy's main axis to the edge of the toy's burnt state and record the moving distance. The difference between the two moving distances is the size of the toy burned in the main axis direction. (3) Display and printing device for test results: When the toy is ignited and burning, press the timing button. After the flame goes out, stop the timing. Use the PLC to automatically record the burning time of the toy. The burning speed of the toy = burning dimension of the toy / burning time. Calculate the burning speed from the measured data and display and print the main axis dimension of the toy, the burning dimension, the burning time, the burning speed, and the environmental conditions. 3. Working Principle The core component of the automatic toy combustion tester is the drive unit consisting of a PLC and three stepper motors. The working principle of the tester is shown in Figure 2. [align=center]Figure 3 Working Principle Diagram of Automatic Combustion Tester[/align] According to the US toy standard combustion test requirements, the height of the positioning rod is set via buttons on the operation panel. The PLC receives all this information, analyzes and processes the data, and outputs a start signal to control the stepper motors to start. After receiving the output signal from the PLC, the stepper motors complete the corresponding operation at the set height. The forward rotation button on the panel is used as an input signal to the PLC, controlling the stepper motor to drive the positioning rod to rotate a certain angle to the main axis direction of the toy. The PLC automatically records this angle as the reference angle for subsequent operations. Then, the forward measurement button is activated. After receiving this input signal, the PLC controls the stepper motor on the positioning rod to drive the scale to measure the main axis dimension L1 of the toy. The PLC automatically records this data and displays it on the panel. After determining the main axis dimension of the toy, the reverse button is activated to return the positioning rod to its original position. After determining the direction and dimensions of the toy's main axis, ignite the toy. Press the timer button on the panel; the PLC receives this signal as a digital input. When the toy extinguishes, press the stop button; the PLC receives this signal as another digital input and outputs a signal to the panel displaying the toy's burning time T. Activating the reset button causes the PLC to control a stepper motor, returning the positioning rod to the previously recorded rotation angle, aligning it with the toy's main axis again. Activating the rewind button moves the scale to the toy's burned edge; the panel displays the rewind distance L2. The toy's burned dimension L = toy's main axis dimension L1 - rewind distance L2, and is displayed on the panel. The PLC automatically calculates the toy's burning speed based on the burned dimension and burning time. Activating the print button sends a control signal to the micro-printer, automatically printing the result. Additionally, the height can be set on the panel according to the toy's height, allowing the positioning rod to rise to a certain height for the pointer on the scale to position the toy's main axis edge. Alternatively, by setting a certain angle, the positioning rod can be rotated to a specific angle before placing the toy on the platform, aligning its main axis with the positioning rod. If there is a deviation, the platform's fine-tuning function can be used to maintain consistency. 4. Functional Characteristics (1) High testing accuracy and fast response speed. The FX1S-10MT PLC is a 12-bit machine, characterized by high accuracy and fast speed, giving the tester excellent testing accuracy and response time. Furthermore, the MC-808MDE microstepping high-performance stepper motor driver adopts a new bipolar cross-current carrier drive technology, with a maximum microstepping of 256 times, enabling the stepper motor to achieve higher speeds and greater high-speed torque. The microstepping function further improves motor operating accuracy, reduces vibration, and lowers noise. (2) Simple operation and convenient use. Operation is simple, requiring only button presses on the control panel. The display screen clearly shows the relevant rotation angles and measured dimensions, making it simple, convenient, and accurate. The use of the tester greatly reduces workload and improves work efficiency. (3) High reliability and strong stability. Due to the high reliability and stability of PLCs, the MC-808MDE microstepping high-performance stepper motor driver features advanced overcurrent protection (peak value exceeding 10A), overvoltage protection (exceeding 85VDC), overheat protection (stops operation at ≥70℃, resumes operation at ≤50℃), and phase reversal protection, making the tester more reliable and safer, and possessing excellent electrical stability and reliability. (4) The tester has a reasonable structural design. The tester has a platform structure, with the operation panel mounted on the base. The stepper motors are encapsulated in support rods and brackets, making them difficult to access. Furthermore, all components of the tester are rust-proofed, and the manufacturing process is carefully considered, facilitating debugging and maintenance. (5) Flexible preset functions. Test speed and time can be preset within a wide range. The preset angle is 0-180°, the preset speed range is 0-6000m/s, and the burning time is 0-90s. (6) Technical specifications: positioning rod rising height is 0-500mm, and rotation angle is 0-90°. The initial position of the positioning rod is 0°. (7) Strong anti-interference capability. Because the PLC components of this tester have photoelectric isolation for digital signals, they can effectively filter out interference from malfunctioning signals. The MC-808MDE microstepping high-performance stepper motor driver has photoelectric isolation for input signals, TTL compatibility for input signals, accepts differential signals, has good heat dissipation and microstepping capabilities, and effectively suppresses vibration interference, electromagnetic interference, and environmental interference. 5. Software Design of the Control System The I/O variables of the automatic toy flammability tester are divided into three categories: digital input signals, digital output signals, and intermediate variables. The digital input signals include: start signal, reset signal, start timing signal, stop timing signal, rise signal, fall signal, forward signal, backward signal, forward rotation signal, and reverse rotation signal; the digital output signals include: run control signal and print control signal; the intermediate variables include: height setting and angle setting. The PLC starts and controls the tester based on the received digital input signals and intermediate variables. The control program is shown in Figure 4. First, the direction of the toy's main axis is determined, and then the main axis dimension is measured. After confirming these parameters, the positioning rod returns to its original position, the toy is ignited, and the timer is started. After the toy burns, the timer stops, the positioning rod returns to the recording position, and the size of the burned toy is measured. The burning time is calculated, the printing device is started, the test results are output, and the test process ends. [align=center] Figure 4 Control Program Diagram of Automatic Combustion Tester[/align] 6 Conclusion This automatic tester uses an advanced Mitsubishi FX1S-10MT PLC controller from Japan and an advanced WJT JQF-MD808 stepper motor driver from the United States, ensuring stable operation, fast response, and high accuracy. Using this tester not only reduces the labor intensity of inspection work but also greatly improves the efficiency of inspection, the accuracy of test results, and the automation level of inspection work. This product has broad application prospects in toy safety testing. The author's innovation: The automatic toy combustion tester was developed by combining PLC control technology with the working principle of a high-performance subdivision drive device and a stepper motor. This device can accurately determine the direction and size of the toy's main axis, ensuring the accuracy of the inspection results. References: [1] Yu Hanqi. Electrical Control and Programmable Controller Application Technology [M]. Nanjing: Southeast University Press, 2003. [2] Zhao Yuehua. Programmable Controller and Its Application [M]. Chengdu: University of Electronic Science and Technology of China Press, 1998. [3] Shen Shibin. Communication Application between Mitsubishi PLC and PC. Microcomputer Information, 2006, 4-1: 81-83.