Corrugated rolls are the core component of corrugated carton production lines, and also one of the most expensive and vulnerable parts. The manufacturing and overhaul of corrugated rolls are inseparable from corrugated roll grinding machines. The processing accuracy and efficiency of the grinding machine directly affect the quality of the corrugated rolls and the company's profits. Currently, the CNC systems used in corrugated roll grinding machines are mainly divided into two categories: one is a general-purpose CNC system such as SIE MENS; the other is a PC-based CNC system. The former has outstanding performance but is too expensive, and its functions and performance are overly redundant relative to the corrugated roll grinding process; the latter has sufficient functions and performance, but its price is still unaffordable for many small and medium-sized enterprises. Therefore, designing and developing a practical, stable, and reliable economical CNC system for corrugated roll grinding machines is of great significance. This paper proposes a design scheme for an economical CNC system for corrugated roll grinding machines based on a single-chip processor. This scheme has significant advantages in both CNC system cost and system functions/performance, and is suitable for the retrofitting of corrugated roll grinding machines. CNC Grinding Machine Technology and Electrical Structure. Corrugated Roll CNC Grinding Machine and Grinding Technology. Corrugated roll CNC grinding machines are usually modified from surface grinders, gantry planers, or gantry milling machines. The corrugated roll CNC grinding machine introduced in this article adopts the bed structure of the M7150 surface grinder. It mainly retains the grinding wheel spindle of the surface grinder. To improve machining accuracy, the lifting control of the grinding wheel head adopts a servo drive, gearbox, and ball screw transmission structure. At the same time, the original hydraulic transmission part of the horizontal slide is eliminated and replaced by an AC servo (Z-axis). A CNC indexing head spindle and a diamond roller head for grinding wheel dressing are installed on this basis. Other auxiliary devices of the surface grinder, such as the bed hydraulic pump, spindle oil pump, and cooling water pump, remain basically unchanged. To simplify the CNC system structure, the control functions for the grinding wheel spindle motor, cooling water pump, and grinding head extension are implemented separately. However, overload protection for all motors is still implemented by the CNC system. The main operating functions of the economical CNC system for corrugated roll grinding machines are as follows. The parameter settings include setting process parameters, workpiece parameters, machine tool effective stroke, and backlash compensation values ​​for each axis via an 8-key keyboard; the machine tool zero-return jog control axis and Z-axis movement adjust the axis and Z-axis positions to the machine tool coordinate zero point, serving as the reference position during grinding; the workpiece clamping jog control of each axis movement achieves workpiece installation and alignment; the establishment of work positions jog control of each axis movement determines the basic work positions of the grinding machine, such as the indexing position, tool setting position, grinding start position, right exit position, and grinding wheel dressing position; grinding wheel dressing determines the rough dressing amount, fine dressing amount, and dressing times of the grinding wheel, and completes the grinding wheel dressing before formal grinding; automatic operation automatically grinds the workpiece according to the set process parameters, workpiece parameters, work position parameters, and grinding wheel dressing parameters. The main processes for each ridge during grinding include: indexing – rough grinding – grinding wheel dressing – fine grinding; software reset – CNC system hot start. The electrical structure of the economical CNC system for the corrugated roll grinding machine is shown in Figure 1. Based on the AD16M4 control board, this system realizes all electrical control functions of the corrugated roll grinding machine. It includes not only LCD display and keypad input, but also digital input (DI)/output (DO) and AC servo motor position/speed control functions. The DI section mainly includes bidirectional limit switch detection for axes A and B, AC servo status alarm input for axes C and D, and overload protection for various power motors. The DO section mainly includes light alarms, sound alarms, intermittent lubrication, axis-to-axis electromagnetic brakes, axis air brakes, and start/stop control of the diamond wheel motor. The three-axis CNC axes use a Yaskawa AC servo system, forming a semi-closed-loop position control structure, with its input signal set to "direction + pulse". The hardware structure of the AD16M4 control board for the economical CNC system of the corrugated roll grinding machine is shown in Figure 2. It mainly consists of a W78E516 main processor, a 74LS373 address latch, a 74LS138 address decoder, main memory, NVRAM 29F040 secondary memory, expansion ports and an 8255B, an AT89C2051 pulse divider, an LCD display board, and a keyboard. The control board uses two data storage chips, namely the NVRAM 29F040. Since the RAM itself lacks power-loss protection, a non-volatile NVRAM 29F040 is added to the system to achieve power-loss protection. The main memory chip has a storage space of 32 KB, used to store variables, page code, and other data that does not require power-loss protection. The secondary memory chip has a storage space of 512 KB, divided into 8 memory sectors by hardware. Sectors are selected by the main processor's P1.4, P1.5, and P1.6 pins. Each sector can be released by erasing the sector. The main processor can access both main and secondary memory using direct addressing, with the selection and switching between the two memory chips controlled by pin .7 of the W78E516. 2. Basic Input/Output: The P1.0, P1.1, P1.2, and P1.3 pins of the main processor W78E516 control the chip select, read/write, and enable signals of the LMG-SSC 240×64 dot matrix LCD display board, respectively. Display data output is achieved through the PA port of the 8255A, and keyboard data is input to the 8255A port via digital input. The PB port of the 8255B detects information such as limit switches, AC servo status, and motor overload. Normally closed contacts should be selected for the limit switches, and the normally closed contacts of all motor thermal relays are connected in series before being input to the control board. The PC7, PC6, and PC4 pins of the 8255A control the light alarm, sound alarm, and intermittent lubrication, respectively. The high 4 bits of the PC port of the 8255B are connected to the PC... 7. Control the on/off state of the X-axis and the electromagnetic brake, air brake, and diamond wheel motor respectively. 3. Motion Control The purpose of motion control is to precisely control the position/velocity/acceleration of the motion control axis. When the system uses "pulse + direction" output, it is necessary to ensure that the pulse and direction are synchronized, and that the total number of pulses is correct, the frequency is accurate, and the frequency change is smooth. In addition, to improve the system reliability, the position control signals (pulse, direction) are output in differential drive form. Since the economical CNC system uses a microcontroller as the main processor, its data processing capability is limited, making it difficult to achieve high-quality control pulses. Therefore, this system uses a pulse divider independent of the main processor to output pulses, which can not only improve the processing speed of the entire system and simplify the program design, but also effectively improve the control accuracy of the pulse frequency. The pulse divider uses an AT89C2051 microcontroller to achieve uniform pulse output. The control software is completely chip-based. The main processor, W78E516B, controls the system operation via an 8255B port extension. The PA port of the 8255B controls pulse output, and the lower 4 bits (PC0-3) of the PC port control the direction of movement for each axis. Two pulse dividers are connected to the PA port of the 8255B. When an interrupt signal is received from the main processor, the pulse divider reads the pulse count from the 8255B port and outputs it evenly. The pulse signals output from the pulse dividers and the direction signals from the PC port of the 8255B are differentially converted and output to the servo drives of the X, Y, and Z axes, respectively. The X and Z axes share a single AT89C2051 pulse output; when .7 is set to "0", the axis pulse is output; when .7 is set to "1", the axis pulse is output. The X and Z axes share a single AT89C2051, with the U axis reserved. The CNC system software design for the corrugated roll grinding machine adopts a modular programming design. The main task modules include key scanning, key value analysis, servo motor control, limit switch detection, AC servo status detection, motor overload detection, light alarm, sound alarm, intermittent lubrication, and LCD display. The main program of the system software scans these task modules in a loop. When the corresponding condition is met, the task is responded to and processed. The keyboard scanning cycle in the main program is approximately 100 ms. Too small a scanning interval makes it difficult to filter out key bounce, while too large a scanning interval may miss key actions. This system uses Timer 11D to implement the interrupt timing of the interpolation cycle. The interrupt service routine mainly completes the calculation of motion control parameters and the output of pulse count. After the system is powered on, to prevent system initialization errors caused by voltage fluctuations during power-on, the program delays for approximately 100 ms. After the delay, variable initialization, chip and hardware port initialization, and output status initialization are performed. During program operation, the LCD display must be refreshed approximately once to prevent the LCD from displaying error messages. The system software displays various operating functions in the form of multi-level menus. Its main menu displays: Parameter Settings, Machine Tool Zeroing, Workpiece Clamping, Station Establishment, Grinding Wheel Dressing, Automatic Operation, Technical Support, and Software Reset. To support these functions, the system buttons adopt a multi-definition method, largely consistent with the soft-key design concept in general CNC systems. However, unlike general CNC systems, this system does not have dedicated numeric input keys; instead, soft-key input is used. Furthermore, the system eliminates the handwheel and jog buttons found in typical CNC systems; their corresponding functions are achieved through a combination of soft keys and multi-speed (coarse/medium/fine/micro) jog buttons. This "software-based" approach significantly simplifies the system's hardware structure while having minimal impact on operational efficiency. 1. Data Management Design: The CNC system needs to store numerous parameters, such as process parameters (grinding amount, rough grinding speed, fine grinding speed), workpiece parameters (height, edge length, edge count), logic stroke protection parameters (axis A, Z-axis), machine tool clearance compensation (axis B, Z-axis, and axis C), and grinding wheel dressing parameters (rough dressing amount, fine dressing amount, dressing times). Furthermore, the height distribution curve table and indexing angle table calculated based on the workpiece parameters also require power-off protection. Since the system uses an incremental position control system, the station information does not need power-off protection. When the system enters the parameter setting page, it displays the data stored in NVRAM. To prevent garbled characters or other errors, the displayed data format and validity need to be checked. If the data is incorrect, a hidden value is forcibly assigned, and the modified parameter is stored in the corresponding sector of the NVRAM. 2. Basic Algorithm Design: The high-frequency algorithm uses a parabola as the high-frequency curve. To reduce the complexity of two-axis motion control, a piecewise linear approximation of the parabola is adopted. First, the corrugated roller length is converted into the corresponding total number of pulses. Then, it is divided into 40 equal segments. The number of pulses corresponding to the high-frequency value of each segment and the slope of each segment are calculated and stored in NVRAM. During high-frequency grinding, the number of pulses that the axis should output in this interrupt cycle is calculated based on the number of pulses and the slope of the current segment's z-axis movement. Indexing Algorithm: Since the microcontroller cannot meet the complex real-time calculation requirements, similar to the high-frequency processing, the indexing calculation is also completed before grinding. Specific calculation method: First, calculate the total number of pulses corresponding to one revolution of the axis. Then, divide the total number of pulses by the set number of ridges and round down to obtain the basic indexing pulse number for each ridge. The remainder is then appropriately processed, and the remainder pulses are evenly inserted into the corresponding ridges according to a certain rule, which is sufficient to ensure uniform indexing. Theoretically, the indexing error does not exceed one pulse, which fully meets the technical requirements of corrugated roll indexing, and there will be no cumulative error even if the shaft rotates continuously for many revolutions. 3. Motion Control Design The pulse interpolation algorithm is the core of motion control. The system software adopts digital integral linear interpolation in the pulse incremental interpolation algorithm. Each interpolation generates a displacement increment and outputs it in the form of a pulse. This control system performs interpolation calculations while machining, which is a typical real-time control method. Therefore, the efficiency of interpolation calculations directly affects the feed speed of the grinding machine. The smaller the interpolation cycle, the higher the contour accuracy. When two axes are linked, the motion control calculation is very large. Therefore, the software design should avoid processing double-precision, long integer variable data as much as possible to simplify the calculation process and reduce processor time consumption. The timing adopted by this system... Click here to download materials: Design of Economical CNC System for Corrugated Roll Grinding Machine Editor: He Shiping