Maintenance of hydraulic sliding table -- technical transformation
Maintenance of hydraulic sliding table -- technical transformation
Sliding table is the main power component of modular machine tool and its automatic line. The accuracy, structural rigidity and technical performance of sliding table have a decisive influence on the technical and economic indexes of modular machine tool and its automatic line, such as working ability, work content, machining accuracy and productivity. The hydraulic slide table is a power component used to complete the feed movement. According to the technological requirements of the parts to be processed, the power box (with multi axle box) and various cutting heads can be installed on it, and matched with the supporting parts to form different forms of modular machine tools, which are used to complete drilling, reaming, boring, countersinking, scraping end face, chamfering, turning end face Milling and tapping. The detection device is installed on the sliding table to complete the feeding action of the automatic detection process.
The HY32B type hydraulic sliding table of horizontal fine boring modular machine tool for thrust surface of cylinder block crankshaft hole is technically reformed and equipped with electro-hydraulic servo control system.
(1) Composition and working principle of hydraulic slide
The hydraulic sliding table is composed of sliding table, sliding seat and hydraulic cylinder. The hydraulic cylinder is fixed on the sliding seat, and the piston rod is fixed under the sliding table. When the pressure oil enters the hydraulic cylinder, the sliding table can move along the guide rail of the sliding seat.
The hydraulic system of the hydraulic sliding table to achieve two feed working cycles, as shown in Figure J, the completed working cycle is as follows: sliding table fast forward one by one, work forward one by two, work forward one by one, stop and fast back.
In the hydraulic system of power sliding table shown in Fig. J, a pressure limiting variable vane pump and a volume throttling speed regulating circuit composed of two speed regulating valves are used in the oil inlet circuit, and a back pressure valve is set in the oil return circuit to stabilize the sliding table
At the same time, the motion stability of the slide is improved. Fast forward and work into the replacement of the use of stroke valve and hydraulic control sequence valve, the speed of the replacement is more stable. At the end of the work, the dead block iron is used to control the rest position of the worktable.
(2) Requirements of machining accuracy for hydraulic position servo system
The depth control of the thrust surface of the cylinder block crankshaft hole is realized by controlling the movement of the sliding table, and the precise control of the sliding table movement depends on the positioning accuracy and repeated positioning accuracy of the servo cylinder. Therefore, in order to ensure the stability of the depth of the hole, higher requirements are put forward for the positioning accuracy of the hydraulic position servo system. In addition, the thrust surface processing needs to feed for many times, and each feed depth is controlled by the position of the servo cylinder. In order to improve the processing efficiency, the servo cylinder is required to reach a stable state in as short a time as possible when changing the position each time. In a word, the requirement of machining accuracy for hydraulic position servo system is to have fast dynamic response and high steady-state accuracy at the same time.
(3) The control principle of electro-hydraulic servo system is developed
As shown in Figure K, the electro-hydraulic servo system of hydraulic sliding table is mainly composed of electro-hydraulic servo valve 2, hydraulic cylinder 1, sliding table driven by piston rod, potentiometer 4, stepping motor, rack and pinion mechanism 5 and proportional amplifier 3. When the moving contact of the potentiometer is in the middle position, there is no voltage output on the contact; When it deviates from this position, it will output the corresponding voltage. The weak voltage produced by the moving contact of the potentiometer needs to be amplified by the proportional amplifier before the electro-hydraulic servo valve can be controlled. The moving contact is driven to rotate by the stepping motor, and the angular displacement and angular velocity of the stepping motor are controlled by the pulse and pulse frequency from the digital control device. The rack is fixed on the sliding table, and the potentiometer is fixed on the gear, so when the sliding table drives the gear to rotate, the potentiometer rotates with the gear to realize negative feedback.
(4) Test results and conclusions