Some operating skills of CNC lathe processing

One, programming skills

As our factory has high requirements for the accuracy of processed products, the following points need to be considered when programming:

One. Parts processing sequence:

Drill first and then flat end (to prevent drilling shrinkage);

Rough turning first, then fine turning (to ensure the accuracy of parts);

The first is the large processing tolerance, and the last is the small processing tolerance (this is to ensure that the surface of the small tolerance size is not scratched and prevent parts from deforming).

2. Choose a reasonable speed, feed rate and cutting depth according to the hardness of the material:

1) Carbon steel should be selected for high speed, high feed rate, and large cutting depth. For example: select 1Gr11, S1600, F0.2, 2mm cutting depth;

2) Low speed, low feed rate and small cutting depth are selected for hard alloy. For example: GH4033, select S800, F0.08, cutting depth 0.5mm;

3) Low-speed, high-speed, and small cutting depth should be selected for titanium alloy. For example: select Ti6, S400, F0.2, 0.3mm cutting depth. Take machining parts as an example: the material is K414, which is a special hard material. After many tests, S360, F0.1 and 0.2 cutting depth were finally selected to process qualified parts.

two. Knife

Tool setting is divided into tool setting instrument and direct tool setting. Most of the lathes in our factory do not have a tool setting instrument, they are directly setting the tool. The tool setting technique mentioned below is direct tool setting.

First, select the center of the right end face of the part as the tool setting point and set it as the zero point. After the machine tool returns to the zero point, each tool that needs to be used will use the center of the right end face of the part as the zero point for tool setting. When the tool touches the right end face, input Z0 and click Measure, then the tool compensation value of the tool will automatically record the measured value, which means that the tool setting of axis Z is correct. The tool setting for axis X is the tool setting for test cutting, and the tool is used to rotate the outer circle of the part. Measure the value of the outer circle of the vehicle (for example, X is 20 mm), enter X20, click Measure, the tool compensation value will automatically record the measured value, and then the X axis is also correct; this tool setting method, even if the machine is powered off, It will not change the tool setting value after power-on. Restart can be applied to the mass production of the same part for a long time, during which there is no need to shut down the lathe.

Three, debugging skills

After the part programming is completed, try cutting and debugging after the tool is completed. In order to prevent program errors and tool setting errors from causing collision accidents, first simulate the empty stroke, move the tool to the right of 2-3 times the total length of the entire part in the machine coordinate system, and then start the simulation processing, confirm the program and simulation processing After completion, the tool settings are correct. Then start machining parts. After the processing of the first piece is completed, a self-inspection is carried out to confirm the qualification, and then a full-time inspection is carried out. Commissioning can only be carried out after the full-time inspection is qualified.

Fourth, complete parts processing

After the first piece of trial cutting is completed, the parts should be produced in batches, but the first piece is qualified does not mean that the entire batch of parts are qualified, because in the processing process, due to different processing materials, the tools will wear, the processing materials are relatively soft, and the tool wear is small , The processing material is hard, and the tool wears quickly. Therefore, during the processing, it is necessary to check frequently and increase or decrease the tool compensation value in time. Ensure that the parts are qualified.

Take the part as an example, the processing material is K414, and the total processing length is 180mm. Because the material is very hard, the tool wears quickly during the machining process. From the start point to the end point, a slight degree of 10-20 mm will occur because of tool wear. Therefore, we must manually add a slight degree of 10-20 mm in the program to ensure that the parts are qualified.

In short, the basic principle of machining is: rough machining first, remove the excess material of the workpiece, and then finish machining; avoid vibration during the machining process; avoid thermal degeneration of the workpiece during the machining process, which may be due to excessive load, etc. Cause; may be caused by the resonance between the machine tool and the workpiece, or it may be