Maintenance and maintenance of mechanical parts of CNC machine tools

Including: maintenance and maintenance of machine tool spindle components, feed transmission mechanism, guide rails, etc.

1. Maintenance and Maintenance of Spindle Parts <br><br><br><br><br> Spindle parts are important components in the mechanical part of CNC machine tools. They are mainly composed of spindle, bearings, spindle accurate stopping device, automatic clamping and chip removal device.
The lubrication, cooling and sealing of the spindle components of numerically controlled machine tools are a few issues that are worthy of attention during the use and maintenance of machine tools.
First of all, a good lubrication effect can reduce the operating temperature of the bearing and prolong its service life. For this reason, it should be noted that during operation and use, grease and oil are circulated and lubricated at low speed, and oil mist and oil-gas lubrication are used at high speed. However, when using grease lubrication, the spindle bearing is usually filled with 10% of the space volume of the bearing. Do not fill it with the grease, because too much grease will increase the spindle heat. For oil circulation lubrication, it is necessary to inspect the spindle lubrication thermostatic oil tank daily during operation to see if the oil quantity is sufficient. If the oil quantity is not enough, add the lubricant oil in time; at the same time, check whether the lubricant temperature range is appropriate.
In order to ensure the spindle has a good lubrication, reduce friction and heat, but also can take away the heat of the spindle assembly, usually using a circulating lubrication system, using a hydraulic pump strong oil lubrication, the use of oil temperature controller to control the tank fluid temperature. High-grade CNC machine tool spindle bearings are lubricated with a high-grade grease sealer, and each grease can be used for 7 to 10 years. The new lubrication and cooling method not only reduces the temperature rise of the bearing, but also reduces the temperature difference between the inner and outer rings of the bearing to ensure that the main shaft has little thermal deformation.
There are two common spindle lubrication methods. The oil-air lubrication method is similar to the oil mist lubrication method. However, the oil mist lubrication method is continuous supply of oil mist, and the oil-air lubrication is the timing of quantitatively sending the oil mist into the bearing gap, thus achieving both Lubrication of the oil mist avoids too much oil mist and pollutes the surrounding air. Injection lubrication method is to use a larger flow of constant temperature oil (each bearing 3 ~ 4l/min) injection to the spindle bearings, in order to achieve the purpose of lubrication, cooling. Here the larger flow injected oil must be drained by the drain pump instead of the natural backflow. At the same time, a dedicated large-capacity high-precision constant-temperature oil tank is also used, and the oil temperature variation is controlled at ±0.5°C.
Second, the cooling of the main shaft components is mainly to reduce the bearing heating and effectively control the heat source.
Third, the seal of the main shaft components not only prevents dust, chips, and cutting fluid from entering the main shaft components, but also prevents leakage of the oil. The seals of the main shaft components are contact and non-contact seals. For contact seals with felt rings and oil-resistant rubber seals, check for ageing and damage. For non-contact seals, to prevent leakage, it is important to ensure that the return oil can be drained as soon as possible, and to ensure the smooth return hole. .
The sealing structure of the front support of the main shaft In summary, the lubrication, cooling and sealing of the main shaft components must be highly emphasized during the use and maintenance of the CNC machine tools, and careful work must be done in this regard.

2. Maintenance and maintenance of the feed transmission mechanism<br> The electromechanical components of the feed transmission mechanism mainly include: servo motor and detection element, deceleration mechanism, ball screw nut pair, screw bearing, moving parts (table, spindle box) Columns, etc.).
Here, the maintenance and maintenance issues of the ball screw nut pair are explained.
(1) Adjustment of the axial clearance of the ball screw nut The ball screw nut has strict requirements on the axial clearance in addition to the accuracy of feed movement in one direction, so as to ensure the reverse transmission accuracy. Therefore, in the operation and use, it should be noted that the axial clearance caused by wear of the screw nut pair is eliminated by adjusting method.
Double nut gasket type anti-backlash This type of structure is simple and reliable, good rigidity, the most widely used, the type of gasket between the two nuts can be pre-adjusted by a professional manufacturer according to user requirements in advance, loading and unloading is very convenient.
The double nut thread type anti-backlash utilizes the external thread on one nut to adjust the relative axial position of the two nuts through the round nut to realize pre-tightening. After adjustment, the other nut is used for locking. This type of structure adjustment is convenient and can be During use, adjustments are made at any time, but the size of the preload cannot be accurately controlled.
The tooth gap type anti-backlash is formed on the flanges of the two nuts respectively with cylindrical external gears, respectively meshing with the internal gears fixed at both ends of the sleeve. The number of teeth is z1 and z2, respectively, and one tooth is different. When adjusting, first remove the ring gear so that the two nuts rotate one tooth with respect to the sleeve in the same direction, and then insert the ring gear. Then the two nuts produce a relative angular displacement, and the axial displacement is:
In the formula, z1 and z2 are the number of gear teeth, and ph is the lead of the ball screw.
(2) Daily inspection of the ball screw nut couple seal and lubrication The daily inspection of the ball screw nut couple seal and lubrication is a problem that we should pay attention to during operation and use. For the screw nut seal, it is necessary to check the seal ring and protective sleeve to prevent dust and impurities from entering the ball screw nut pair.
Lubrication of the screw nut is regularly lubricated if grease is used, and if oil is used, care must be taken to inject oil through the oil hole.

3. Maintenance and Maintenance of Machine Tool Guides <br><br><br><br><br><br><br><br><br><br><br><br><br> The maintenance and maintenance of machine tool guides are mainly the lubrication of guide rails and the protection of guide rail
(1) Lubrication of guide rails The purpose of guide rail lubrication is to reduce frictional resistance and frictional wear to avoid creeping at low speeds and to reduce temperature rise at high temperatures. Therefore, the lubrication of the guide rail is very important. Lubricating oil is used for sliding guide rails, and lubricating oil or grease can be used for rolling guide rails. The grades of lubricants commonly used for CNC machine tools are: l-an10, 15, 32, 42, and 68. The oil lubrication of the guide rail is generally automatic lubrication. We must pay attention to checking the diverter valve in the automatic lubrication system during operation. If it fails, it will cause the guide rail to not be automatically lubricated. In addition, the amount of oil in the guide rail lubricant tank must be inspected daily. If the oil amount is not enough, the lubricant should be added in a timely manner; at the same time, check whether the lubricant pump can be started and stopped regularly, and check whether the lubricant can be provided when checking the timing start. .
(2) Protection of guide rails During operation and use, care should be taken to prevent chips, abrasive particles, or cutting fluids from scattering on the guide rails. Otherwise, the guide rails will be abraded, scratched, and rusted. To this end, we must pay attention to the daily inspection of the guide rail protection device to ensure the protection of the guide rail.

4, the circumference of the rotary table Maintenance <br> CNC machine tool feed movement is generally implemented by a rotary table, the machining center, the rotary table has become an indispensable member. Therefore, in the operation and use, it is necessary to pay attention to the correct operation and use of the rotary table in accordance with the requirements and operating instructions. Pay special attention to the lubrication of the rotary table drive mechanism and guide rails.