How to maintain the precision engraving machine of knife die?

When maintaining the precision engraving machine, it is necessary to start from mechanical parts, electrical system, lubrication system, cutting auxiliary system and other aspects to ensure the accuracy of the equipment and prolong the service life. The following are detailed maintenance procedures and key points:

I. Daily maintenance (before each startup/after processing)

1. Cleaning of mechanical parts

Worktable and guide rail:

Use a brush or compressed air to clean the metal chips, oil stains and dust on the workbench and linear guide rail, so as to avoid the guide rail from being scratched or stuck due to chip accumulation (focus on cleaning the slider groove and the side of the guide rail).

If the materials that are easy to stick chips such as aluminum parts are processed, it is necessary to wipe the surface of the guide rail with alcohol or special cleaning agent to prevent aluminium scrap from wearing the guide rail after residual hardening.

Installation parts of spindle and cutter:

After machining, wipe the spindle end face and the mounting hole of the tool holder to remove cutting fluid residues and metal chips, so as to avoid impurities from affecting the installation accuracy of the tool (the coaxiality error should be ≤0.01mm).

When stopping for a long time, apply anti-rust oil to the taper hole of the spindle and cover it with a protective sleeve to prevent rust or bump.

2. Inspection of fasteners and transmission parts

Check whether the tool rest, table fixing screws and guide slide locking screws are loose (tighten them with torque wrench according to the torque required in the manual, for example, the torque of M6 screw is usually 8-12 nm).

Observe whether the belt drive device (such as the spindle belt) has cracks or looseness, press the belt with your fingers, and adjust the motor position to tighten the belt when the deflection exceeds 10 mm.

Second, the weekly maintenance (once a week)

1. Lubrication system maintenance

Lubrication of guide rail and lead screw:

According to the requirements of the equipment manual, add special lubricating oil (such as ISO VG32 guide oil) to the linear guide rail and ball screw through a manual oiler or an automatic lubricating pump, and the oil injection amount of each shaft is about 5-10mL.

For manually lubricated equipment, it is necessary to ensure that the lubricating oil path is unobstructed (clean cotton thread can be inserted into the oil hole to check whether there is oil). If the oil path is blocked, it is necessary to blow through or remove the oil pipe with compressed air to clean it.

Spindle bearing lubrication:

Some engraving machine spindles are lubricated with grease (such as lithium-based grease), and the grease needs to be replenished through the grease nozzle of the spindle end cover every week (each filling amount should not exceed 1/3 of the volume of the bearing cavity, so as to avoid the spindle heating caused by excessive grease).

2. Maintenance of cutting fluid system

Check the liquid level of the cutting fluid tank, and if it is insufficient, add the same type of cutting fluid (it needs to be diluted according to the instruction, such as the emulsion dilution ratio of 1:10-1:20).

Clean up the chips and impurities deposited at the bottom of the water tank. If the cutting fluid has peculiar smell, emulsion stratification or blackening, it needs to be completely replaced (the replacement cycle is usually 2-4 weeks, depending on the frequency of use).

Three, monthly maintenance (once a month)

1. Precision calibration and parameter inspection

Spindle verticality calibration:

Use marble platform and dial indicator, press the meter head against the end face of the spindle, and manually rotate the spindle (360). The reading deviation of the dial indicator should be ≤ 0.02 mm. If it is out of tolerance, adjust the spindle mounting base or contact the manufacturer for maintenance.

Worktable flatness detection:

Check the workbench with a precision level and a feeler gauge. The insertion clearance of the feeler gauge should be ≤0.03mm/100mm. If the flatness is out of tolerance, it may be that the workbench is deformed or the screws are loose, so it needs to be readjusted and fixed.

Parameter backup of CNC system:

Backup system parameters (such as servo gain, reverse clearance compensation value, PLC program) through U disk or computer to prevent equipment failure caused by parameter loss (backup once a month is recommended).

2. Electrical system inspection

Open the electric cabinet, clean the dust inside with an insulating brush, and check whether the contacts of contactors and relays are oxidized (if the contacts are black, gently polish them with fine sandpaper).

Measure the insulation resistance of each motor terminal (with a megger, the insulation value should be ≥10MΩ). If the insulation is poor, check whether the cable is broken or damp.

Four, quarterly maintenance (once a quarter)

1. Deep maintenance of transmission parts

Ball screw disassembly and cleaning:

Loosen the bearing seats at both ends of the lead screw, withdraw the lead screw from the nut, clean the thread of the lead screw and the raceway of the nut with kerosene, remove old grease and metal debris, and then apply new high-temperature grease (such as molybdenum disulfide grease), and ensure that the parallelism error between the lead screw and the guide rail is ≤0.05mm/1000mm during installation.

Guide rail slider inspection:

Remove the slider end cover, check whether the ball is worn or rusted (if the ball surface is dented or discolored, the slider assembly needs to be replaced), clean it, re-apply lubricating oil and install it.

2. Maintenance of cooling and gas circuit system

Spindle cooling system:

Check the circulating water tank of the water-cooled spindle, replace the antifreeze (it is recommended to use deionized water or special cooling liquid to prevent scale deposition), and clean the inside of the water tank and the pipeline (it can be circularly washed with citric acid solution, and then washed with clear water after scale removal).

Pneumatic components (if any):

Clean the filter element of the air filter, drain the water from the drainer, and check whether the air pipe leaks (soapy water can be applied for detection, and the air pipe or connector needs to be replaced at the bubbling place).

V. Annual maintenance (once a year)

1. Comprehensive accuracy check

Please ask professional engineers to use laser interferometer to detect the positioning accuracy and repetitive positioning accuracy of equipment (such as X/Y axis positioning accuracy ≤0.03mm/1000mm and repetitive positioning accuracy ≤0.01mm), and pitch error compensation or mechanical adjustment is required when the deviation exceeds.

Check the tool change accuracy of the tool magazine (if any) to ensure that the repeated positioning error during tool exchange is ≤0.02mm, otherwise the positioning pin or transmission mechanism of the tool magazine needs to be adjusted.

2. Replacement of key components

Replace the spindle bearing (it is usually recommended to replace it after 1-2 years, depending on the frequency of use), select high-precision bearings (such as P4 angular contact ball bearings), and control the pre-tightening force during installation to avoid abnormal heating of the spindle.

Check whether the cable (especially the cable in the towing chain) is aging or broken, and replace the cable with severe wear to prevent short circuit or poor contact.

VI. Suggestions on Maintenance of Special Scenes

1. When stopping for a long time

Before cutting off the power supply, apply antirust oil to all guide rails and lead screws, and cover the equipment with dust cover to avoid dust accumulation.

Start and run for 30 minutes every two weeks (idle running each shaft) to prevent the grease of motor bearing from curing, and at the same time charge the capacitor of numerical control system to prolong the life of electrical components.

2. After processing special materials

After processing high-hardness materials such as tungsten steel and cemented carbide, it is necessary to check the temperature rise of the spindle bearing (the temperature is ≤60℃ during normal operation, and it needs to be stopped for inspection when it exceeds 70℃), and shorten the monitoring period of tool life (such materials wear the tool faster).

After processing soft metals such as copper and aluminum, clean up the metal dust that may penetrate into the electric cabinet in time (which may easily lead to short circuit), and purge the encoder interface of servo motor with compressed air.

Seven, maintenance records and fault early warning

Establish an equipment maintenance ledger to record the time, content, replaced parts and parameter adjustment of each maintenance, so as to trace the equipment status.

Pay attention to abnormal signals in equipment operation (such as abnormal spindle noise and increased servo alarm frequency), and timely investigate potential faults (for example, if the roughness of the machined surface suddenly deteriorates, which may be due to worn guide rails or loose tools, stop the machine immediately for inspection).

summary

The maintenance of the precision engraving machine of knife die should follow the principle of "prevention first, combining prevention with control", and form a standardized process from cleaning, lubrication, precision calibration to component replacement. Especially for high-precision machining (for example, the tolerance of the cutter die is required to be ±0.01mm), it is necessary to focus on the wear of the transmission system and the parameter stability of the numerical control system, and if necessary, use professional instruments for testing to ensure the best performance of the equipment for a long time.