Numerical control machine tool to improve the machining accuracy and efficiency

One, programming skills

Numerical control programming is the most basic work of numerical control machining. We can start from the ingenious use of inherent procedures, reduce the cumulative errors of CNC system, flexible use of main procedures and subroutines and so on.

1, flexible use of the main program and subroutine

In the process of complex mold processing, generally adopt the form of one mold and many pieces for processing. If there are several parts of the same shape on the mold, should be flexible use of the main program and subroutine relationship, in the main program repeatedly call subroutine, until the completion of processing. It can not only ensure the consistency of machining size but also improve its machining efficiency.

2, reduce the cumulative error of the numerical control system

Generally use the incremental approach to programming artifacts, is used as a benchmark for processing, so many consecutive period of program will produce certain cumulative error, try to use absolute manner when programming so programming, make each segment based on workpiece origin, so it can reduce the cumulative error of CNC system, ensure the machining accuracy.

Machining precision is mainly used to produce products, machining precision and machining error are terms to evaluate machining surface geometric parameters. However, the actual parameters obtained by any machining method are not absolutely accurate. From the point of view of the part's function, as long as the machining error is within the tolerance range required by the part drawing, the machining accuracy is considered to be guaranteed.

Machining accuracy refers to the degree to which the parts are machined with the actual geometric parameters (size, shape and position). The difference between them is called machining error. The machining error reflects the machining accuracy. The larger the error, the lower the machining precision, the smaller the error, the higher the machining precision. The following is a brief introduction of the methods to improve the machining accuracy of the workpiece:

1. Adjust the process system

(1) adjustment of test cutting method through test cutting - measurement of size - adjustment of the tool's amount of draft - cutting - re-test cutting, and so on until the required size. This method has low production efficiency and is mainly used for small batch production.

(2) the adjustment method obtains the required size by pre-adjusting the relative positions of the machine tool, fixture, workpiece and cutter. This method has high productivity and is mainly used for mass production.

Two, reduce the machine tool error

(1) the rotary precision of the bearing should be improved:

Select high precision rolling bearing;

(2) the use of high-precision multi-oil chipping pressure bearing;

(3) the use of high-precision static bearing

(2) to improve the accuracy of bearing phase accessories:

(1) to improve the box support hole, spindle journal processing accuracy;

Improve the machining accuracy of the surface matched with the bearing;

(3) measure and adjust the radial run-out range of the corresponding parts to make the error compensation or phase offset.

(3) properly preload the rolling bearing:

Can eliminate the gap;

Increase the bearing stiffness;

(3) homogenize rolling error.

(4) the rotation precision of the spindle is not reflected on the workpiece

Three, reduce the transmission chain transmission error

(1) few transmission pieces, short transmission chain, high transmission accuracy;

(2) it is an important principle to ensure the transmission accuracy to adopt the deceleration transmission, and the closer to the end of the transmission pair, the smaller the transmission ratio should be;

(3) the precision of the end part shall be higher than that of other driving parts.

Reduce tool wear

(1) the tool must be resharpened before the tool size wear reaches the sharp wear stage

(2) select special cutting oil for full lubrication

(3) the material of the cutting tool shall conform to the technological requirements

To reduce the stress and deformation of the process system

(1) improve the stiffness of the system, especially the stiffness of the weak links in the process system;

(2) reduce the load and its variation

Reduce the thermal deformation of the process system

(1) reduce the heat source and isolate the heat source

(2) equilibrium temperature field

(3) adopt reasonable structure of machine tool parts and assembly datum

(4) accelerate to achieve heat transfer equilibrium

(5) control the ambient temperature

Reduce residual stress

(1) add heat treatment procedure to eliminate internal stress;

(2) reasonably arrange the process.

Above is the method of machining workpiece to reduce errors, reasonable arrangement of process can effectively improve the accuracy of the workpiece.

Two, reasonable setting processing route

Reasonable setting of machining route and machining sequence is an important basis for optimizing machining program. It can be considered from the processing track and the way of feed.

In the workpiece CNC milling processing, want to learn UG programming access to learning materials in group 496610960 can help you to combine the workpiece process requirements to choose the right way to feed, in order to ensure the workpiece cutting precision and processing efficiency. When milling the surface profile of a plane workpiece, the cutting line of the cutter should be arranged. As far as possible along the contour curve of the extension line, cut out, so as not to appear at the junction of the knife marks. At the same time in the milling process should be selected according to the workpiece conditions or the reverse milling.

Three, tool selection and correct installation

Whether it is CNC processing or ordinary processing, because the tool is directly acting on the workpiece, so its selection and installation of the workpiece machining precision and surface quality of the most important factors. In particular, the workpiece is processed in the CNC machining center, the tool is stored in the tool library in advance, once the processing can not be replaced at will. So the general principle of tool selection is: easy to install and adjust, good rigidity, durability and high precision.

Reasonable selection of cutting parameters

The determination of cutting parameters is an important content of CNC machining process, its size is an important parameter of the main movement and feed movement of the machine tool, has an important impact on the workpiece machining accuracy, machining efficiency and tool wear. The choice of cutting parameters includes cutting speed, backdraft and feed. The basic selection principle is: under the condition of allowable stiffness, the rough machining takes a larger cutting depth, in order to reduce the number of times of cutting and improve the productivity of the workpiece; In order to obtain higher surface quality, the machining depth is usually smaller