The most popular five axis linkage head swing or w

2022-08-01
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Five axis linkage head swing or workbench swing

five axis machine tools are more and more used in the mold industry. The five axes of a five axis machine tool are usually composed of three linear axes plus two rotary axes, but their structural modes are very different. Different structural forms will cause some differences in rigidity, dynamic performance and accuracy stability of machine tools. This paper mainly analyzes and compares two five axis machine tools with different structures: vertical spindle swing and vertical spindle stationary table swing (cradle type), so that users can fully understand their structural forms, which is conducive to selecting appropriate machine tools according to their product characteristics and economic ability

the rotation point and detection center of the head swing machine tool are located on the spindle, as shown in Figure 1. The rotation point and detection center of the table swinging machine tool are located on the bed of the machine tool, as shown in Figure 2

Figure 1 rotation point and detection center of head swing machine tool and worktable swing machine tool

Figure 2 Schematic diagram of detection center of head swing machine tool and cradle type worktable swing machine tool

here, taking the rotation axis of the two machine tools rotating 90 ° to process the spatial vertical hole on the same part as an example, the differences between the two machine tools are explained

Figure 3 this part needs to process two mutually perpendicular through holes on two adjacent surfaces

1 Rigidity comparison of machine tool spindle

head swing during machining, the rigidity of the spindle is relatively poor due to spindle swing; The table swinging machine tool will not have any impact on the rigidity of the spindle due to the table swinging

2 Efficiency comparison of machine tool processing

due to different rotation points, when the tool tip achieves the same displacement, the spindle of the head swing machine tool needs to swing at a larger angle (similar to the lever principle), so the efficiency of the head swing machine tool is lower when processing the same parts

3. Influence of tool length on machining accuracy of machine tool

swing error = swing arm × Swing angle

for the head swing machine tool, the tool length is a part of the swing arm

that is, in the case of head swing, the length of the tool affects the length of the swing arm and amplifies the error. That is, the error will increase with the length of the tool, as shown in Figure 1. As shown in Figure 2, for the cradle table swing machine tool, 29 new chemical materials in the fields of special rubber, engineering plastics, film materials, electronic chemicals, etc. are listed as advanced basic materials. The tool length has nothing to do with the length of the swing arm. The relationship between the machining error and tool length of the head swing machine tool and the cradle table swing machine tool will show that the tensile performance of the composite storage tank based on carbon nanotube fiber is better than that of the traditional epoxy carbon fiber composite. It can be clearly shown in Figure 4 and figure 5

Figure 4 Relationship between tool length and position error in head swing machine tool

Figure 5 Relationship between length and position error of cradle table swing machine tool

4 With the swing, both kinds of machine tools will produce position error, but the head swing machine tool will also produce shape error, while the workbench swing will not produce shape error

the tool rotation of the head swing machine tool will produce position error. At the same time, the feed direction of the machined hole deviates from the rotation center of the tool, as shown in Figure 6. Therefore, when the machined hole produces position error, it will also produce shape error and wedge-shaped hole

Figure 6 the head swing machine tool will produce shape error while generating position error

while the position error of the workbench swing machine tool is caused by the workbench swing. The feed direction of the spindle and the rotation center of the tool always coincide, so there will be no additional shape error. This is another obvious advantage of the cradle table swing compared with the head swing

Figure 7 the swing machine tool of the cradle table does not produce shape error

the defect of simple function of the single chip microcomputer has been improved by the microcomputer 5 Comparison of the size range of five axis machining

with the swing of the spindle of the head swing machine tool, the machining range in the diameter direction of the workpiece will be reduced, that is, the swing angle of the spindle will eat up the stroke, resulting in the diameter range of the largest workpiece that can be machined by the five axis machining is smaller than that of the three axis machining; The table swing of the table swing machine tool will not have any impact on the horizontal dimension of the workpiece. In this sense, the workpiece size range is the same for five axis machining and three-axis machining. However, the interference caused by the structure of the machine tool should be considered for the maximum range of five axis machining workpiece. The user should ask the machine tool supplier to provide five axis machining interference diagram for analysis and comparison. Generally, the five axis machining range of a machine tool with a cradle type table swing structure is larger than that of a head swing machine tool at the same stroke

conclusion

the cradle type worktable swing machine tool spindle has good rigidity and high processing efficiency; The tool length has no effect on the machining accuracy; Machining will not produce shape error; With the same stroke, the five axis machining range of the machine tool will be larger than that of the head swing machine tool

the rigidity of the spindle of the head swing machine tool is relatively poor, and the machining efficiency is relatively low; The machining accuracy will decrease with the increase of tool length; Machining will produce shape error; When the spindle swings at an angle, it will eat up the stroke, resulting in the reduction of the maximum workpiece size that can be machined

in addition, the table swinging machine tool needs to overcome the self weight of the workpiece. If the workpiece is very heavy, it has higher requirements for the clamp; In addition, when machining large and heavy parts, the machine tool can not realize the swing of the workbench, so it can only use the head swing

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