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How to maintain and maintain the mechanical parts and auxiliary devices of CNC machine tools?

Time:2021-06-09 Views:174

Mechanical parts and auxiliary devices are important components of CNC machine tools. Among them, the mechanical part mainly includes: machine tool spindle parts, employer lead screw nut pairs, guide rail lights. The auxiliary devices mainly include: CNC indexing head, automatic tool changing device, hydraulic pressure system and cooling and lubricating device. Therefore, it is part of the entire maintenance and maintenance work of CNC machine tools during daily maintenance and maintenance.    

Maintenance and maintenance of mechanical parts    

The maintenance and maintenance of the mechanical part of the CNC machine tool mainly includes: the maintenance and maintenance of the machine tool spindle components, feed transmission mechanism, guide rails, etc.  

1. Maintenance and maintenance of main shaft components

The main shaft component is an important component of the mechanical part of the CNC machine tool. It consists of the main main shaft, bearing, spindle stop device, automatic clamping and chip removal device. The lubrication, cooling and sealing of the spindle components of CNC machine tools are several issues worthy of attention during the use and maintenance of the machine tools.

First of all, a good lubrication effect can reduce the working temperature of the bearing and prolong its service life. For this reason, it should be noted in operation and use: at low speeds, use grease and oil circulating lubrication; at high speeds, use oil mist and oil-air lubrication. However, when grease is used for lubrication, the enclosed amount of the spindle bearing is usually 10% of the bearing space volume. Do not fill it up at will, because too much grease will aggravate the heating of the spindle. For oil circulating lubrication, check the main shaft lubrication constant temperature mailbox every day during operation to see if the oil volume is sufficient. If the oil volume is insufficient, add lubricating oil immediately; at the same time, check whether the lubricating oil temperature range is appropriate.    

In order to ensure good lubrication of the main shaft, reduce friction and heat generation, and at the same time take away the heat of the main shaft components, a circulating lubrication system is usually used, with a hydraulic pump for strong oil lubrication, and an oil temperature controller to control the temperature of the oil in the tank. The spindle bearings of high-end CNC machine tools are lubricated by high-grade grease sealing, and it can be used for 7-10 years every time the grease is added. 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 thermal deformation of the spindle is small.    

There are two common spindle lubrication methods. The oil-air lubrication method is similar to the oil-mist lubrication method, but the oil-mist lubrication method enables continuous supply of oil mist, while the oil-air lubrication method sends the oil mist into the bearing gap regularly and quantitatively. The oil mist lubrication prevents too much oil mist from polluting the surrounding air. The injection lubrication method is to inject into the spindle bearing at a constant temperature with a larger flow rate to achieve the purpose of lubrication and cooling. Here, the oil injected with a larger flow rate must be forced to drain by the drain pump instead of returning naturally. At the same time, a dedicated large-capacity high-precision constant temperature mailbox is also used, and the oil temperature change is controlled within 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 spindle components not only prevents dust, chips and cutting fluid from entering the spindle components, but also prevents the leakage of lubricating oil. There are contact and non-contact seals for the main shaft components. For contact seals using linoleum rings and oil-resistant rubber seals, pay attention to checking for aging and damage; for non-contact seals, in order to prevent leakage, it is important to ensure that the return oil can be drained as soon as possible, and to ensure that the return hole is unobstructed .

2. Maintenance and maintenance of feed transmission structure    

The electromechanical components of the feed transmission mechanism mainly include: servo motor and detection components, reduction mechanism, ball screw nut pair, screw bearing, moving parts (worktable, headstock, column, etc.).  

(1) Adjustment of the clearance of the ball screw nut pair in the axial direction     

In addition to the requirements for the accuracy of the single-direction feed motion of the ball screw nut, it also has strict requirements for the axial clearance to ensure the accuracy of the reverse transmission. Therefore, in the operation and use, attention should be paid to the axial gap caused by the wear of the screw nut pair to be eliminated by adjustment methods. Double nut washer type anti-backlash, double nut thread type anti-backlash, tooth difference type anti-backlash.

(2) Daily inspection of the sealing and lubrication of the ball screw nut pair

The daily inspection of the sealing and lubrication of the ball screw nut pair is a problem we should pay attention to in operation. For the sealing of the screw nut, it is necessary to check the sealing ring and protective sleeve to prevent dust and impurities from entering the ball screw nut pair. For the lubrication of the screw nut, if grease is used, lubricate it regularly; if lubricating oil is used, pay attention to frequent oil injection through the oil injection hole.    

3. Maintenance and maintenance of machine tool guide rails

The maintenance and maintenance of the machine tool rails are mainly the lubrication of the rails and the protection of the rails. 

(1) Lubrication of guide rails    

The purpose of guide rail lubrication is to reduce frictional resistance and frictional wear in time to avoid low-speed crawling and reduce temperature rise at high temperatures. Therefore, the lubrication of the guide rail is very important. For sliding guides, lubricating oil is used; while for rolling guides, lubricating oil or grease can be used. Check the amount of oil in the lubricating oil tank of the guide rail. If the amount of oil is insufficient, add lubricating oil immediately; at the same time, pay attention to check whether the lubricating oil pump can start and stop regularly, and pay attention to check whether the lubricating oil can be provided during the timing start.

(2) Protection of guide rails    

In operation and use, attention should be paid to prevent chips, abrasive particles or chip liquid from being scattered on the surface of the guide rail, otherwise it will cause increased wear, abrasion, and corrosion of the guide rail. For this reason, pay attention to the daily inspection of the guide rail protection device to ensure the protection of the guide rail.  

4. Maintenance and maintenance of rotary table                          

The maintenance and maintenance of the auxiliary devices of the CNC machine tools mainly include: the maintenance of the CNC indexing head, the automatic tool changer, and the hydraulic hydraulic system.  

1. Maintenance and maintenance of CNC indexing head              

The CNC indexing head is a commonly used accessory for CNC milling machines and machining centers. Its function is to make rotary indexing or continuous rotary feed motion according to the instructions of the CNC device, so that the CNC machine tool can complete the instruction processing accuracy. Therefore, in operation Pay attention to the correct operation and use in strict accordance with the instructions and operating procedures of the CNC indexing head.    

2. Maintenance and maintenance of automatic tool changer     

The special structure of the machining center is different from other CNC machine tools in the automatic tool change device. It has the function of automatically changing the required cutting tools according to the requirements of the processing technology to help the CNC machine tool save auxiliary time and meet the requirements of completing multiple processes and steps in one installation. Therefore, in the operation and use, pay attention to frequently checking whether the mechanical structure of each component of the automatic tool changer works normally and whether there are abnormal phenomena; check whether the lubrication is good, etc., and pay attention to the reliability and safety of the tool change.    

3. Maintenance and maintenance of hydraulic system    

(1) Regularly check, filter and replace the oil in the mailbox;     

(2) Check the working performance of the cooler and heater, and control the oil temperature;

(3) Regularly check and replace the seals to prevent leakage of the hydraulic system;  

(4) Regular inspection and cleaning or replacement of hydraulic parts, filter elements, regular inspection and cleaning of mailboxes and pipelines;  

(5) Strictly implement the daily inspection system to check whether the leakage, noise, vibration, pressure, temperature, etc. of the system are normal.    

4. Maintenance and maintenance of pneumatic system    

(1) Choose a suitable filter to remove impurities and moisture in the compressed air;     

(2) Check the oil supply of the lubricator in the system to ensure that there is an appropriate amount of lubricating oil in the air to lubricate the pneumatic components to prevent rust and wear from causing air leakage and component failure;     

(3) Maintain the air tightness of the pneumatic system and regularly check and replace the seals;   

(4) Pay attention to adjusting the working pressure;     

(5) Regularly check and clean or replace pneumatic components and filter elements.

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