Analysis of hydraulic automatic bar feeder vibration
1. hydraulic vibration bar feeder.
The machining efficiency and bar installation of hydraulic CNC lathe bar feeder can greatly improve the small shaft, sleeve type and small parts of the rate. But the structure of this device is more complex, in use after a period of time, due to various factors, the feeder work will produce vibration, the vibration and sometimes very serious. The maximum speed of vibration occurred not only limits the lathe spindle turning speed, not up to the requirements of the process, influence the workpiece machining accuracy and surface quality, but also an important component of the internal feeder, such as guide tube, piston and push rod feeding damage caused by vibration, serious when even the CNC lathe can not work normally.
The cause of vibration and the measures to solve the 2. feeder
The hydraulic bar feeder has a tube to six tube structure according to the different types of can. At the back of each feeding guide tube, there is a bar feeding device as shown in figures 3, 8 and 1, consisting of a push rod, a piston and a special hydraulic valve, and the front end of the pusher rod has a rod end end centering cone.
Feeder work, bar between the clamping spring in CNC lathe clamp and push rod centering cone, rotation of the lathe spindle driven by a special hydraulic valve between the piston and the push rod of the hydraulic oil controlled release, in the bar and the guide tube forming oil film evenly distributed between the supporting role of hydraulic power bar rotary motion to produce bar, and even the existence of the film but also to avoid the friction bar and the guide tube. In order to make the feeder in good working condition in the rotating rod material, preparation of the bar has the following requirements:
1) for the centering cone on bar has good centering in rotation, the tail rod material should be pre processed as shown in Figure 3-9, which is to ensure the bar tail cone and cone angle of the cone angle and the same centering cone rod and cone rod axis coaxial. The combination of the bar and the centring cone after the process is shown in the right section of figure 3-8. On the contrary, the combination of the tail of the rod and the centering cone without pre processing is shown in figure 3-10. It is obvious that the centering cone has no definite centering effect on the tail of the bar. The position of the material varies with the feed time, resulting in unstable movement of the rod when it is rotated, causing uneven oil film between the rod and the guide tube and causing partial rupture of the oil film. This not only makes the fluid force generated by the rotation of the bar of the bar even lose support, will make the inner bar and the guide pipe have serious friction, thus causing vibration, and bar tail will damage to the centering cone.
2) bar must meet the straightness of the cluster is less than or equal to 0.5mm. The purpose of this requirement is to ensure that the gap between the bar and the inner wall of the guide tube is within the allowable range, that is, at about 2~, at which point the guide tube is the best for the bar material. When the bar passes straight, the gap between the bar and the inner wall of the guide tube will be too small, which will damage the oil film evenly distributed between the rod and the centering cone and cause vibration. In order to ensure the straightness requirement of the bar, two measures can be taken: matching a bar straightener, aligning the bar with straightness more than required; shortening the length of the bar to process.
3) when choosing the diameter of the guiding pipe hole, the gap between the hole size and the bar material should not be too large, so as to avoid vibration due to the lack of the supporting role of the hydraulic power of the rod. When there is no suitable diameter of the guide tube, only shorten the length of the bar, and properly reduce the spindle speed of the lathe.
