1, different structures

Three-axis vertical NC machining center is three axes that move linearly in different directions, that is, up and down, left and right, front and back. The up and down direction is the spindle, which can rotate at high speed. Four-axis vertical machining center adds a rotating shaft on the basis of three axes, that is, the horizontal plane can rotate 360 degrees, but it cannot rotate at high speed.

2, the scope of use is different

Three-axis machining center is the most widely used. Three-axis machining center can carry out simple plane machining, and only one side can be machined at a time. Three-axis machining center can process materials such as aluminum, wood and EPC well.

Four-axis machining centers are used less than three-axis machining centers. Multi-faceted machining of products can be realized through rotation, which greatly improves the machining efficiency and reduces the clamping times. Especially the processing of cylindrical parts is more convenient. And can reduce the repeated clamping of the workpiece, improve the overall machining accuracy of the workpiece, simplify the process and improve the production efficiency. Shorten production time.

Second, the programming method:

1, part drawing analysis

According to the drawings of parts, by analyzing the requirements of materials, shapes, dimensions and accuracy, surface quality, blank conditions, heat treatment, etc. of parts, the processing contents and requirements are defined, and the appropriate CNC machine tools are selected.

This step includes:

1) Determine the type or machine tool of the machined part.

2) What kind of fixture or clamping method is used?

3) Determine which cutter or how many cutters to use for machining.

4) Determine the machining route, that is, select the tool setting point, the program starting point (also known as the machining starting point, which often coincides with the tool setting point), the cutting route and the program ending point (which often coincides with the program starting point).

5) Determine cutting parameters, such as cutting depth and width, feed speed and spindle speed.

2, determine the process

On the basis of analyzing the drawings of parts, determine the processing technology (such as determining the positioning mode and selecting the fixture, etc.). ) and processing route (such as determining the tool alignment point and feed route, etc. ) parts, and determine the cutting amount. Process treatment involves many contents, mainly including the following points:

1) Determination of processing methods and process routes According to the principle of giving full play to the functions of CNC machine tools, reasonable processing methods and process routes are determined.

2) When designing and selecting tools and fixtures, factors such as processing method, cutting amount and workpiece material should be comprehensively considered to meet the requirements of convenient adjustment, good rigidity, high precision and good durability. When designing and selecting NC machining fixture, the positioning and clamping process of workpiece should be completed quickly to reduce the auxiliary time.

And try to use the combined fixture to shorten the production preparation cycle. In addition, the fixture used should be easy to install on the machine tool and coordinate the dimensional relationship between the workpiece and the machine tool coordinate system.

3) The selection of cutter location is the starting point of program execution, and the selection should be based on the principles of simplifying program preparation, easy alignment, easy inspection during machining and reducing machining errors.

The tool alignment point can be set on the workpiece to be processed, or on the fixture or machine tool. In order to improve the machining accuracy of parts, the tool setting point should be set on the design benchmark or process benchmark of parts as far as possible.

4) Determination of processing route When determining the processing route, ensure the accuracy and surface roughness of the processed parts; Try to shorten the feed route and reduce the empty feed stroke; It is beneficial to simplify numerical calculation and reduce the number of program segments and programming workload.

5) Determination of cutting parameters The cutting parameters include cutting depth, spindle speed and feed speed. The specific numerical values of cutting parameters should be determined according to the provisions of the instruction manual of CNC machine tools, the materials of the workpiece to be processed, the processing content and other technological requirements, and combined with empirical data.

6) Determination of cooling liquid Determine whether it is necessary to provide cooling liquid during machining, whether it is necessary to change tools, and when to change tools.

Because the process of machining parts in CNC machining center is very concentrated, rough machining, semi-finish machining and finish machining are often needed under one clamping. When determining the process, we should carefully and reasonably arrange the processing sequence of each process to improve the processing accuracy and production efficiency.

3. Numerical calculation

Numerical calculation is to calculate the input data needed for NC machining according to the geometric size of the part and the determined machining route. The universal numerical control system has the functions of linear interpolation, circular interpolation and tool compensation. For the contour machining of parts with simple shapes (such as parts composed of straight lines and arcs), the coordinate values of the starting and ending points of geometric elements, the center of arcs, the intersection or tangent point of two elements, etc. are calculated.

For parts with complex shapes (such as parts composed of non-circular curves and surfaces), straight lines or arc segments are used for approximation, and node coordinate values are calculated according to accuracy requirements. This situation needs to be calculated with the help of computers and related software.

4, write the processing program

After the process and mathematical treatment are completed, the parts processing program should be written paragraph by paragraph according to the instructions of the numerical control system, the format of the program segment, the process, the numerical calculation results and the auxiliary operation requirements, and according to the program instructions and format requirements specified by the numerical control system.

Before programming, programmers should know the performance, function and program instructions of CNC machine tools, so as to write the correct NC machining program.

5, program input

Will write a good program, input into the numerical control system, commonly used methods are as follows:

1) manual input on the operation panel of CNC milling machine;

2) Using DNC (data transmission) function, first input the program into the computer, and then input the machining program into the CNC system through special CNC transmission software, and then transmit it out for execution, or process it while transmitting.

6, program verification

The compiled program must be checked for program operation. In general, the machining program can only be used for formal machining after calibration and cutting. You can check the correctness of the motion trajectory and action of the machine tool by means of empty cutting and empty running diagram.

It is more convenient to use graphic simulation tools in CNC machine tools with graphic display function and dynamic simulation function or in CAD/CAM software to cut workpieces. But these methods can only check whether the motion trajectory is correct, but can't check the machining accuracy of the machined parts.