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The overall structure and principle of stone engraving machine

2018-08-06


The overall structure and principle of stone engraving machine


YONGDA-The overall structure and principle of stone engraving machine

1. The working principle of stone engraving machine

The stone engraving machine is actually a three-dimensional numerical control system, and its working principle is as shown:


Figure 1 Working principle of stone engraving machine

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The special design and layout software installed in the general-purpose microcomputer is used for graphic and text design, typesetting, automatic generation of processing path information, and the tool path data is transmitted to the single-chip microcomputer through the USB interface or other data transmission interface, and the numerical control system receives the tool path data and completes the display. After interacting with the user-series function, the input path information is converted into numerical control information by a specific algorithm, and the controller converts the information into a signal (pulse train) for driving the stepping motor or the servo motor to control the engraving machine X, Y. , Z three-axis walking. At the same time, milling, you can engrave a variety of flat or three-dimensional graphics text designed on the computer to achieve automatic processing of engraving.


2. Stone engraving machine mechanical structure and motion system design
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This part focuses on the selection of various components of the stone engraving machine, including: effective engraving area, structure and parameters of the ball screw, structure type and parameters of the linear guide, structure type and parameters of the main motor, stepper motor The type of structure and parameters, the transmission mode and speed range of the main motion and the feed motion;


2.1 Overall structural design

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The mechanical body part of the stone engraving machine is the skeleton of the engraving machine and has a base, a column, a work table, a machine head and a spindle assembly. Under the premise of ensuring the mechanical rigidity of the whole system, in order to simplify the design structure, reduce the weight of the whole machine, and shorten the design and manufacturing cycle of the product, the main frame is made of aluminum alloy drawn profile and rolled aluminum plate, and plastic for protection parts. Parts and sheet metal parts are manufactured using standard fasteners and locating pins.


2.2 Main motion plan design

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The main motion scheme of the stone engraving machine usually has two options: directly using a dedicated engraving head or using a DC motor to drive the spindle mechanism. The true current motor plus the pulley can also meet the requirements of the spindle speed, and it is also cheaper, but it will increase the complexity of the mechanical structure. The advantages of the special engraving head are not repeated here, and the frequency conversion speed control device matched with it is simple and practical, so a special engraving machine motor is used.


2.3 Feed motion design

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As described above, the beam is fixed and the table is moved to realize the relative motion. The head moves on the beam (X direction) to realize the engraving width; the table moves on the base (Y direction) to realize the engraving length; the spindle assembly Move up and down (Z direction) to achieve engraving depth. Since the ball screw pair has many advantages, the transmission members in each kinematic chain use a ball screw pair. The stepper motor and the ball screw pair are directly connected. As for the guide rails, the support members in each kinematic chain adopt rolling linear guide pairs. Stone Research Institute (micro signal stone5A)


3. Stone engraving machine control system design

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3.1 Structure and principle of the stone engraving machine control system

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The stone engraving machine is a processing system capable of loading a CNC engraving program and automatically controlling the movement of the engraving machine. It usually consists of an engraving program calculation system and a numerical control system. The working principle is: the computer digitizes the engraving graphics required by the engraving software, and generates an engraving program (generally G code, HPGL format file) for each step, and transmits it through a USB interface or other data transmission interface (RS232, RS485, etc.). To the control system, then the control system uses a specific algorithm to convert the input path information into numerical control information, and the controller converts the information into a signal (pulse train) that drives the stepper motor or the servo motor to control the engraving machine X, Y, z. The three-axis feed, at the same time, the high-speed rotary spindle of the stone engraving machine drives the workpieces according to the processing materials, and mills the workpiece fixed on the mechanical body to engrave various flat or three-dimensional graphics characters designed on the computer. Automated machining of engraving.

3.2 Overall design of the control system of stone engraving machine

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It is known from the design indicators of the system that the goal is to design and develop a set of universal embedded engraving machine numerical control system that can meet the control characteristics of stone engraving machine and meet the control requirements of stone engraving machine and has high-cost performance. Therefore, the system needs to start from the speed aspect, focus on solving the problem of rapid movement, while taking into account the manufacturing cost of the system, so that the hardware cost control is within the expected range. It can be seen that the processing speed and lost control of the system are the key points that should be considered in the design of the system.



According to the development level of the existing numerical control technology, there are several ways to improve the processing speed of the numerical control system:

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1) PC+ high-speed motion control card;


2) Industrial control board composed of high-performance general-purpose CPU, such as X86, Pentium, etc.;

3) high-speed motion control chip;

4) Replace high-speed motion control chip with high-performance single-chip microcomputer such as ARM;


Through a systematic comparison of the performance, implementation difficulty, workload, and cost of the above four high-speed numerical control schemes, the system adopts the fourth scheme, which is based on the high-performance ARM to develop a numerically-friendly numerical control system for stone engraving machines.

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