The smooth quality of the BT-200 universal tool grinding machine is essential
The universal tool grinding machine is a common machine tool for machining. There are high requirements for motion stability, commutation accuracy, and commutation frequency. The large-scale high-speed precision surface grinder has large inertia. When it is reversed, it will cause a sharp increase in back pressure, which will lead to a reversing impact. This will have a catastrophic effect on the machine tool, so the commutation stability has become a constraint grinding machine. An important factor in the progress of work speed and machining accuracy.
The computation method and the commutation control parameters in the system play a decisive role in the commutation impact, and the precision surface grinder is hydraulically driven. Planning a new hydraulic reversing system has burned eyebrows. The following discusses the reversing impact of the grinding machine from the point of view of the reversing method and the steering strategy.
At that time, there were many hydraulic transmission reversing methods used in the BT-200 universal tool grinder. For the analysis of the common hydraulic transmission reversing method, it was faced with a brief analysis.
A pull rod is connected to the reversing spool to reversing the stroke reversing valve. The automatic commutation is accomplished by advancing the pull rod using the travel stop on the workbench. When the workbench moves slowly, when the reversing valve reaches the center position, no matter whether the hydraulic cylinder is placed in two chambers or all of them are pressurized or oiled, or both are closed, there is no hydraulic pressure in the two chambers of the hydraulic cylinder. The advance will cause the workbench to stop, so the reversing valve cannot reach the other end, which presents the so-called "dead point"; when the workbench moves at a high speed, the block pushes the pull rod to change the direction of the reversing valve very fast. The pressure of one chamber of the hydraulic cylinder suddenly drops from the working pressure p to 0. The other chamber rises from 0 top, which presents a great commutation impact. At present, this system is used more on small grinding machines.
Reversing method for selecting electromagnetic reversing valve
The reversing signal is announced by the stroke stop advancement stroke switch, and the stroke reversing valve is changed to the reversing method of the electromagnetic reversing valve. The electromagnet action pushes the spool valve to reverse direction, which can avoid the "dead point". However, it is a switch type hydraulic valve that opens or closes according to the command moment, that is, instantaneously turns on or blocks the oil passage. Such a hydraulic reversing system is There is a big shock during the reversal.
Reversing method for selecting electro-hydraulic reversing valve
The control valve advances the main valve to reverse the direction. The pilot valve is not changed forward, and the replacement of the electromagnetic reversing valve with the electrohydraulic reversing valve constitutes a new reversing method. The electro-hydraulic reversing valve is composed of a pilot valve electromagnetic slide valve and the main valve hydraulic slide valve. This system is operated by the pilot valve switching control. The direction of the oil flow in the control oil circuit is not changed, the reversing valve is always kept at the original end, the direction of the main oil path is not changed, and the work table can always continue to advance.