Maintenance and maintenance of mechanical parts and auxiliary devices of CNC machine tools

Mechanical parts and auxiliary devices are an important part of CNC machine tools. Among them, the mechanical part mainly includes: machine tool spindle parts, ball screw nut pairs, guide rails and the like. The auxiliary device mainly includes: a numerical control indexing head, an automatic tool changing device, a hydraulic air pressure system and a cooling lubricating device. Therefore, their daily maintenance and maintenance is one of the whole maintenance and maintenance work of CNC machine tools.

Maintenance and maintenance of a mechanical part

The maintenance and maintenance of the mechanical part of the CNC machine tool mainly includes the maintenance and maintenance of the spindle parts of the machine tool, the feed transmission mechanism and the guide rail.

1. Maintenance and maintenance of spindle components

The spindle component is an important component in the mechanical part of the CNC machine tool. It is mainly composed of the spindle, bearing, spindle quasi-stop device, automatic clamping and chip removal device. Lubrication, cooling and sealing of CNC machine tool spindle components are several issues worthy of attention during machine tool use and maintenance.

First of all, good lubrication effect can reduce the working temperature of the bearing and prolong the service life. For this reason, it should be noted during operation and use: grease lubrication and oil circulation lubrication are used at low speed; oil mist and oil lubrication are adopted at high speed. However, when grease lubrication is used, the amount of seal of the spindle bearing is usually 10% of the bearing space volume. Do not fill it at will, because too much grease will increase the spindle heat. For oil circulation lubrication, in the operation and use, it is necessary to check the spindle lubrication constant temperature tank every day to see if the oil quantity is sufficient. If the oil quantity is not enough, the lubricating oil should be added in time; at the same time, check the temperature range of the lubricating oil.

In order to ensure good lubrication of the main shaft, reduce friction and heat, and at the same time take away the heat of the spindle assembly, a circulating lubrication system is usually used, which is lubricated by a hydraulic pump, and the oil temperature controller is used to control the temperature of the oil tank. The high-end CNC machine tool spindle bearings are lubricated with advanced grease storage methods, which can be used for 7 to 10 years. The new lubrication cooling method not only reduces the bearing temperature rise, but also reduces the temperature difference between the inner and outer rings of the bearing to ensure that the thermal deformation of the main shaft is small.

There are two common lubrication methods for the main shaft. The oil and gas lubrication method is similar to the oil mist lubrication method. However, the oil mist lubrication method is to continuously supply the oil mist, and the oil and gas lubrication is to regularly and quantitatively feed the oil mist into the bearing gap. The oil mist is lubricated, which avoids too much oil mist and pollutes the surrounding air. The injection lubrication method is to inject a large amount of constant temperature oil (3 to 4 L/min per bearing) into the spindle bearing to achieve lubrication and cooling. Here, the oil injected at a larger flow rate must be forced to drain by the oil discharge pump instead of naturally returning. At the same time, it is also necessary to use a dedicated high-capacity high-precision constant temperature fuel tank, and the oil temperature variation is controlled at ±0.5 °C.

Second, the cooling of the main shaft components is mainly to reduce bearing heat and effectively control the heat source.

Third, the sealing of the main shaft components not only prevents dust, debris and cutting fluid from entering the main shaft components, but also prevents leakage of lubricating oil. The seals of the spindle components are contact and non-contact. For contact seals with linoleum rings and oil-resistant rubber seals, pay attention to check the aging and damage; for non-contact seals, in order to prevent leakage, it is important to ensure that the oil return can be drained as soon as possible, to ensure the smooth return hole .

Sealing structure supported by the front of the spindle

In summary, in the use and maintenance of CNC machine tools, the lubrication, cooling and sealing of the spindle components must be highly valued, and this work should be done carefully.

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