Anyang Xingyang Machine Tool Co., Ltd. (Anyang Xingpu Machine Tool Co., Ltd.
Zhao Guangqing: 137-0372-2538
High valley: 135-233-30323
Wang Ming: 139-37236227
Address: Dongfeng Industrial Agglomeration Zone, Long'an District, Anyang City, Henan Province
Our company mainly produces CW6163C series, standard 80 series, CW61100C series machine tools and CK6163C series CK6180 series CK61100C series CNC machine tools. At the same time according to user requirements to produce various mechanical products, production and sales of various product spare parts and assembly components.
What factors will be encountered in machine tool processing to affect accuracy?
On the road of machine tool processing, all enterprises are committed to making their products infinitely close to zero error. However, the ideal is full and the reality is always very skinny. In the actual processing process, the accuracy of the machine tool will be more or less affected. The influence of various internal and external factors. The forming movement of the tool relative to the workpiece during processing is generally completed by the machine tool, so the machining accuracy of the workpiece depends largely on the accuracy of the machine tool. Machine tool manufacturing errors have a greater impact on workpiece processing accuracy: spindle rotation errors, guideway errors, and drive chain errors. And if the machine tool is subject to wear and tear, it will further reduce the working accuracy of the machine tool.
The first thing to mention is the spindle rotation error. Everyone who is engaged in machining knows that the spindle of a machine tool is the basis for clamping a workpiece or a tool, and transmits motion and power to the workpiece or tool. Therefore, the spindle rotation error will directly affect the accuracy of the workpiece being processed. Spindle rotation error refers to the variation of the actual rotation axis of the spindle relative to its average rotation axis at each instant. It can be decomposed into three basic forms: radial circular runout, axial runout and angular swing.
The main reasons for the main shaft radial rotation error are: coaxiality errors of several sections of the main shaft journal, various errors of the bearing itself, coaxiality errors between bearings, and main shaft winding. However, their influence on the radial rotation accuracy of the spindle varies with different processing methods.
For example, when turning a circle on a lathe with a sliding bearing structure as the main shaft, the direction of action of the cutting force F can be considered to be generally time-invariant. Under the action of the cutting force F, the main journal has different positions and the bearing inner diameter. When a certain fixed part is in contact, the roundness error of the main shaft journal has a great influence on the radial rotation accuracy of the main shaft, and the roundness error of the bearing inner diameter has little effect on the radial rotation accuracy of the main shaft; when boring on a boring machine Because the action direction of the cutting force F rotates with the rotation of the main shaft, under the action of the cutting force F, the main shaft always contacts a fixed part of its journal with different parts of the inner surface of the bearing. Therefore, the inner surface of the bearing The roundness error has a large impact on the radial rotation accuracy of the spindle, while the spindle neck roundness error has a small effect.
Different machining methods cause different machining errors caused by spindle rotation errors. When machining the outer circle and the inner hole on a lathe, the radial rotation error of the spindle can cause the roundness and cylindricity of the workpiece, but it has no direct impact on the machining of the end surface of the workpiece. The spindle axial rotation error has little effect on the machining of the outer circle and the inner hole, but it has a greater impact on the perpendicularity and flatness of the machined end face. When turning threads, the main axis rotation error can cause periodic errors in the lead of the processed thread. Properly improving the manufacturing accuracy of the spindle and the box body, selecting high-precision bearings, improving the assembly accuracy of the spindle components, balancing the high-speed spindle components, and pre-tensioning the rolling bearings, etc., can all improve the rotation accuracy of the machine tool spindle.
The second is the guide rail error. The guide rail is the reference for determining the relative position relationship of the machine tool components on the machine tool, and it is also the benchmark for the movement of the machine tool. The accuracy requirements of the lathe guide are mainly the following three aspects: straightness in the horizontal plane, straightness in the vertical plane, and parallelism (distortion) of the front and rear guide rails.
In addition to the manufacturing error of the guide rail itself, the uneven wear and installation quality of the guide rail are also important factors that cause the guide rail error. Guide rail wear is one of the main reasons for the decline in machine accuracy. In addition, there is the transmission chain error, which refers to the error of the relative movement between the transmission elements at both ends of the transmission chain. It is generally measured by the rotation angle error of the end elements of the transmission chain.
It is worth mentioning that the geometric error of the tool has a great impact on the machining accuracy. The influence of the tool error on the machining accuracy varies with the type of the tool. When a fixed-size tool is used to form the tool into a tool, the manufacturing error of the tool is Will directly affect the machining accuracy of the workpiece; for general tools (such as turning tools), its manufacturing error has no direct impact on the machining accuracy of the workpiece.
During the cutting process of any tool, wear is unavoidable, and the size and shape of the workpiece are changed. The correct selection of cutting tool materials and the selection of new wear-resistant cutting tool materials, the reasonable selection of cutting tool geometric parameters and cutting amount, the correct sharpening of cutting tools, the correct use of coolant, etc., can effectively reduce the size and wear of cutting tools. When necessary, a compensation device can also be used to automatically compensate for tool size wear.
It is to be said that the geometric error of the fixture will also affect the accuracy of the machine tool. The role of the fixture is to make the workpiece correspond to the correct position of the tool and the machine tool, so the manufacturing error of the fixture has a great influence on the machining accuracy (particularly the position accuracy) of the workpiece.