Due to the adjustment of the company's product structure, it is necessary to use C725 multi-blade semi-automatic hydraulic lathe to process the outer diameter of the bearing ring with a diameter of 250mm or more. Due to the large difference between the width and wall thickness of the product, during the machining process, the upper tool holder and the lower part There is mutual interference between the hydraulic systems of the tool holder, which directly affects the quality of the processed workpiece. Improvement measures were proposed after analyzing the hydraulic system of the machine tool.
1. Analysis of the causes of interference in the hydraulic system
As can be seen from Figure 1, the hydraulic system is supplied by a DYBP-40 variable vane pump, and the pressure of the hydraulic system is determined by the vane pump.
The static characteristic curve of the DYBP-40 variable vane pump is shown in Fig. 2.
The AB segment is the fast-forward and fast-retracting segment of the tool holder, and the BC segment is the working segment of the tool holder. When the upper and lower tool holders process the ferrule at the same time (the outer diameter of the upper tool holder and the wall thickness of the lower tool holder), if the upper and lower tool holders advance at the same time, the output flow curve of the pump is AB segment. When transferring to the work, the flow curve of the pump is BC section. At this time, the hydraulic system maintains a high pressure and the flow rate is small. Since the outer diameter of the processing ring is larger than the wall thickness, the lower tool post is first processed and converted to Rewinding, the flow required by the hydraulic system increases. According to the characteristics of the DYBP-40 variable vane pump, the output flow of the pump increases and the pressure decreases. At this time, the upper tool post is cutting, the pressure is suddenly reduced, and the upper tool post is lowered. There is a reduction in the speed of the pass or a pause. After the lower tool holder is quickly retracted, the upper tool holder is transferred to normal cutting. For the above reasons, the processed ferrule has a small boss on the outer diameter, which affects the processing quality.
2. Improvement measures
Through the analysis of the hydraulic system, it was decided to use the YB1-25/25 vane pump instead of the DYBP-40 variable vane pump, and two Y-25B overflow valves were installed to adjust the system pressure, and the two pumps from the vane pump The mouth supplies oil to the upper and lower tool holders respectively, as shown in Fig. 3, which avoids the mutual interference of pressure between the upper and lower tool holders, which improves the processing quality of the machine tool.
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