How to Select the Spindle System of CNC Machining Center
The spindle system of CNC machining center is one of the important executive parts of the forming movement of the machining center, which is composed of spindle power, spindle drive, spindle components, etc. As the machining center has higher machining efficiency, wider application range and higher machining accuracy, its spindle system must meet the following requirements:
1. It has high accuracy and stiffness, stable transmission, low noise, and machining accuracy of machining center is closely related to the accuracy of spindle system. The accuracy of spindle components includes rotation accuracy and motion accuracy. Rotation accuracy means after assembly The radial and axial runout values of the front working part of the spindle under no-load and low-speed rotating conditions. The rotating extruding degree of the spindle assembly depends on the geometric accuracy, assembly accuracy and adjustment accuracy of each part in the assembly. Motion accuracy The rotation accuracy of the folding spindle in the T-operation state. This accuracy is usually quite different from the rotation accuracy in the open stop or low-speed state It is shown in the constant change of the spindle center position when working, that is, the spindle center drift. The rotation accuracy under the motion state depends on the T-working speed of the spindle, the bearing performance and the balance of the spindle components.
Static stiffness reflects the ability of spindle components or parts to resist static external loads. Most machining centers use bending stiffness as the bending scale to balance the stiffness of spindle components. There are many factors that affect the 4-curve stiffness of the spindle components, such as the size and shape of the spindle Main shaft bearing type, number, configuration A, pre tightening, bearing span and overhang of the front end of the main shaft.
2. It has a larger speed regulation range R and realizes the infinitely variable speed machining center. In order to ensure that reasonable cutting parameters can be selected during machining, the highest productivity, plus 1: accuracy and surface quality can be obtained At the same time, it should meet the processing requirements of various processes and processing materials. The spindle system of the machining center must have a wider speed range. At present, the spindle system of the machining center basically realizes stepless speed change.
3. It has the automatic tool clamping function and the prominent feature of the napkin heart is the automatic tool change function. To ensure the continuous implementation of the machining process, the spindle system of the machining center is compared with other spindle systems. Must have automatic knife clamping function
4. Good vibration resistance and thermal stability When CNC machining centers are machining, the interference of impact force and alternating force caused by intermittent cutting, large and uneven machining allowance, high and unbalanced speed of moving parts, and self vibration in the cutting process will cause vibration of the spindle and affect machining accuracy and surface roughness In serious cases, it may even damage the parts in the tool and spindle system. The heating of the spindle system will cause thermal deformation of all parts, damage the relative positioning accuracy and motion accuracy, and cause the error of adding T. For this reason, the spindle assembly should have a high natural frequency string, maintain a proper fit clearance, and conduct cyclic lubrication.
In fact, it is difficult to solve the problem of whether a three-axis CNC machining center is better or a four-axis machining center is better. There is only a problem that is not suitable for machining some kinds of parts. Basically, all three-axis machining centers can process the parts that can be processed by a four axis machining center, while the parts that can be processed by a four axis machining center may not be processed by a three-axis machining center.
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