Development of CK6130 minitype CNC lathe

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Development of CK6130 small CNC lathe

Abstract: using ordinary PC as the host of Huizhou CNC system, the stepping motor drive power adopts pulse width modulation circuit and smooth subdivision circuit, and the CNC lathe body is transformed by using the old ordinary lathe and installed with a 4-position electric tool rest for receiving letters, so as to realize the multi-function and low-cost automation of the lathe

at present, economic CNC machine tools are still the CNC machine tools with the largest market demand and sales volume in China. Using the existing idle old machine tools and making it a new efficient and multi-functional economic NC machine tool through numerical control transformation is an effective method to revitalize the stock funds and one of the ways to realize automation at low cost. CK6130 small CNC lathe developed by us is the exploration and practice of this idea

1 working principle

ck6130 small CNC lathe is composed of microcomputer CNC system and machine body. When processing the workpiece, first compile the numerical control program of the workpiece, then key the verified and feasible numerical control program to the numerical control device, and then the numerical control device calculates the feed pulse sequence according to the program instructions. Then the multi-functional NC board carries out pulse distribution, and forms the control signal of the driving device after power amplification by the power amplifier or driving power supply, so as to control the rotation speed, start and stop of the machine tool spindle, Grease the movement direction, speed and displacement of the system, as well as the selection of cutting tools, the start and stop of cooling and lubrication after the experiment of the clamping plate inlay workbench. Make the cutting tool, workpiece and other auxiliary devices work in strict accordance with the sequence, stroke and parameters specified in the NC program, so as to process parts with shape, size and accuracy that meet the requirements

2 microcomputer numerical control system

this machine tool adopts an open-loop economic control system that controls the x-axis and z-axis to realize the linkage of the two axes, and can complete the linear interpolation of the two coordinates. It is mainly composed of microcomputer, stepping motor drive power supply, stepping motor, multifunctional NC interface board, control circuit, etc. (Figure 1). The microcomputer can choose any kind of microcomputer and compatible machine above ibmpc-286, insert the numerical control card in its bus slot, and use the developed lathe numerical control software package to store the workpiece processing program in the workpiece program memory with power down protection function through keyboard keys, so as to improve the reliability of system operation and complete the NC processing of workpiece

Figure 1 overall scheme of CNC machine tool control system

the stepping motor drive power supply adopts pulse width modulation circuit and smooth subdivision circuit, so as to greatly improve the rising torque of the stepping motor at high frequency, improve the fast performance of the system, reduce the vibration of the stepping motor at low frequency, and make the operation more stable. In addition, it also has the protection functions of overtemperature, overpressure, overcurrent and undervoltage

photoelectric combiner is also used in the system for isolation to improve the anti-interference of the system

3 machine tool body

the machine tool body of CK6130 CNC lathe is improved from small ordinary lathe c615, mainly including the transformation of feed transmission system, main transmission system and tool rest structure

1) transformation of feeding system

z-axis (longitudinal) feeding system is shown in Figure 2. Remove the feed box, chute box, light screw and lead screw of the original machine tool, arrange the stepping motor at the left end of the original lead screw, and install the reduction gearbox by using the installation hole and pin hole of the feed box of the original machine tool. The stepping motor adopts primary gear reduction, and Alcoa directly produces 3D printing products. The transmission gear adopts double sheet gear to eliminate the gap. Replace the original screw with a ball screw and place it at the original screw position. The ball screw adopts the pre tightening installation method to reduce or eliminate the bending deformation caused by the self weight of the screw, so that the tension and compression stiffness of the screw is greatly improved. When working, the stepping motor is connected with the reducer through the gapless coupling to transmit the driving torque to the ball screw pair and drive the carriage to move back and forth longitudinally

Figure 2 Schematic diagram of transformation of 2-axis feeding system

the x-axis (transverse) feeding system installs the stepping motor on the carriage and drives the ball screw through the primary gear reduction

2) transformation of the main speed change system

install a photoelectric encoder at the rear end of the main shaft, and use the combination of electromagnetic clutch and sliding gear to transform the manual step speed change of c615 lathe into automatic step speed change, so that it has the characteristics of convenient operation and simple structure. At the same time, use a two speed motor to further increase the number of speed changes. In a period of time, the current changes: 0.08A - 0.12A - 0.08A - 0.12A Range change: 0.1a- 0.5a- 0.1a- 0.5A Then the final test range is 0.5A

3) transformation of tool rest structure

the ordinary manual indexing tool rest of the original c615 lathe is replaced by the receiving 4-position electric tool rest, which is controlled by the numerical control system. When working, after receiving the signal sent by the microcomputer, during the execution process, the signal of the current tool position is sent back to the microcomputer by the hall element circuit on the tool holder for each rotation and tool change of the tool holder, which is judged by the microcomputer. When the current tool position meets the requirements of the microcomputer, the signal of the locking of the tool holder and the completion of the execution is sent back to the microcomputer (Fig. 3)

Figure 3 block diagram of tool rest work flow

4 functional characteristics of lathe

the NC system of this machine tool adopts general PC, the machine tool body adopts ordinary c615 lathe, and the programming adopts color full screen display and man-machine dialogue. The machine tool can complete NC machining programming, program inspection, syntax correction d) the fluctuation range of power supply voltage does not exceed ± 10% of the rated voltage, graphic display, simulation processing, automatic setting of operating parameters, and control the whole automatic machining process of the machine tool. It has the function of machining cylinder, cone, arc, end face, forming surface, thread and other complex shapes and composite surfaces. The NC software package is open, with reserved interfaces, expandable functions and software upgrades, and has the remarkable characteristics of low-cost automation. (end)

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