Machine tool accuracy adjustment and commissioning

June 28, 2022

Latest company news about Machine tool accuracy adjustment and commissioning

After the normal operation of the equipment, adjust the bed level of the machine tool, coarse adjustment of the main geometric accuracy of the machine tool, and then adjust the relative position of the main moving parts reassembled and the host, such as manipulator, knife library and the host tool position adjustment and correction. Alignment of exchange position between APC tray station and machine tool workbench, etc. When these are completed, the holes reserved for anchor bolts of the main engine and accessories can be filled with quick-drying cement concrete. After 3~5 days of cement solidification, the machine can be fine-tuned.

In the CNC system and machine tool online power test, although the CNC system has been confirmed, working normally, without any alarm, but in case of prevention, should be connected to the power at the same time, ready to press the emergency stop button, in order to be ready to cut off the power at any time. For example, if the feedback signal line of the servo motor is connected inversely or broken, there will be the phenomenon of "flying" of the machine tool. In this case, it is necessary to immediately cut off the power supply and check whether the wiring is correct. Under normal circumstances, there may be a small rotation when the motor is first energized, but the automatic drift compensation function of the system causes the motor shaft to return immediately. After that, even if the motor is powered on again and disconnected, the motor shaft will not turn. You can observe whether the motor rotates by switching on and off the power for many times or pressing the emergency stop button, so as to confirm whether the system has automatic drift compensation function.

When checking the movement of each axis of the machine tool, use manual continuous feed to move each axis, and check whether the moving direction of the machine tool parts is correct through the display value of CRT or DPL(digital display). If the direction is opposite, the motor power line and detection signal line should be connected. Then check whether the moving distance of each axis is consistent with the moving instruction. If not, check whether the relevant instructions, feedback parameters and position loop gain are set correctly.

Then, the handwheel feed, at low speed to move each shaft, and make them meet the limit switch, in order to check whether the limit is effective, whether the CNC system in the overrange alarm.

Finally, a return to baseline action should be performed. The machine tool reference point is the program reference position of the machine tool for processing. Therefore, it is necessary to check whether there is a return to the reference point function and whether the location of the reference point is exactly the same each time.


I. Test the accuracy and function of machine tools

The level of the main bed of the machine tool is fine adjusted with foot bolts and pad iron on the solidified foundation. After the level is adjusted, the moving parts of the bed (column, slide plate and table, etc.) are moved to observe the change of the machine tool level in the whole process of each coordinate, and the geometric accuracy of the machine tool is adjusted accordingly to make it within the allowable range. For medium-sized CNC machine tools above, multi-point cushion iron support should be used to adjust the bed level in free state. Each supporting point is supported behind the bed, and the foot bolts are pressed symmetrically to prevent additional distortion and deformation, improving and maintaining the geometric accuracy of the machine tool.

The detection tools used are precision level, standard square ruler, flat ruler, parallel light tube and so on. In the adjustment, mainly to adjust the pad iron, if necessary, can slightly change the guide insert and pre - tightening roller. Generally speaking, as long as the quality of the machine is stable, the machine can be adjusted to the factory accuracy through the above adjustment.

Allow the machine to move automatically to the tool exchange position. Manually adjust the position of the loading manipulator and unloading manipulator relative to the spindle. In the adjustment of the use of a proofreading heart bar for detection, there is error can adjust the manipulator stroke, mobile manipulator support and knife library position, if necessary, can also modify the setting of knife position point (change the parameters of the NUMERICAL control system). After the adjustment is completed, tighten the adjustment screws and the tool store foundation screws, and then install several tool handles with the quality close to the specified allowable quality to carry out automatic reciprocating exchange from the tool store to the main shaft for many times. It is required that the action is accurate, no collision, no knife drop is qualified.

The machine tool with APC switching table should move the table to the switching position, adjust the relative position of the tray station and the switching table surface, and achieve the smooth, reliable and correct movement when the table automatically changes. Then 70%~80% of the allowable load is installed on the working table, and the automatic exchange action is carried out for many times. After reaching the correct position, the relevant screws are fastened.

Carefully check the numerical control system and programmable controller is in line with the random file specified in the data set parameters, and then test the main operating functions, operation schedule, safety measures, common instruction execution and so on, such as manual operation mode, inching mode, automatic operation mode, stroke limit protection, spindle shift instruction, speed instruction at all levels and other instructions, etc. Whether the execution is correct. Check whether the auxiliary functions and nearby work are working properly, and whether the machine lighting, cooling shield and various protective plates are complete.

Fill the coolant box with coolant to test whether the nozzle can spray coolant normally; In the case of the use of cooling shield whether coolant leakage; Chip removal device can work properly; The constant temperature oil tank of machine tool spindle can work. Through the above inspection and debugging of the machine tool, it has made full preparation for the overall operation test of the machine tool.

Two, trial operation

Due to the functions of CNC machine tools, in order to ensure its long-term automatic operation in use, after its installation and debugging, the reliability of its work must be tested. Users often check the function and reliability of machine tools comprehensively through automatic operation for a long time under certain load conditions. Generally divided into empty running test and load test.

1. Empty running test

Including the main motion and feed motion system running test. The test should be carried out according to the relevant standards promulgated by the state, now taking the processing center as an example, as follows.

The main drive of the infinitely variable speed should be operated in no less than 12 speed classes from low to high, and the running time of each speed should be no less than 2min. The actual deviation of rotation speed ranges from -2% to 6%. The running time of the highest speed should be no less than 2h, so that the temperature of the front and rear bearings of the spindle is not more than 60℃ after reaching a stable temperature. The idle power of the main drive system shall be assessed according to the design regulations. For the moving parts on the coordinate axis, the air operation tests were carried out at low speed, medium speed, high speed feed and fast movement respectively. The moving parts moved smoothly without crawling and vibration phenomenon. The actual deviation of feed speed at all levels is -5~3%. The test of the rotation axis is similar to that of the straight axis, with an actual deviation range of ±5%.

2. Functional test

The function test of machine tool is divided into manual function test and automatic function test.

(1) Manual function test includes:

(1) At least 10 times on the main shaft lock knife, loose knife, blowing test;

(2) Carry out 10 forward, reverse, stop and quasi-stop tests on the spindle at a medium speed;

③ For the feed system, carry out 10 kinds of variable speed test (including low, medium, high speed and fast);

④ The indexing table for 10 times of indexing, positioning test;

⑤ For the switching table, three consecutive switching in and out test;

The knife library, manipulator test, especially for the heaviest, longest, the largest diameter of the tool test, manipulator maximum load test, and determine the tool change time;

Test the indicators, keys and peripherals;

⑧ To carry out tests on other auxiliary devices. Automatic test, is to use the program to control the movement of each part of the machine tool test.

(2) Automatic function test includes:

(1) The spindle of the machine tool at the medium speed of 10 consecutive positive rotation, reverse start, stop and directional quasi stop test;

(2) Repeated variable speed test on the main drive;

(3) Low, medium and high speed change tests are carried out on the moving parts of each coordinate axis, and positive and reverse continuous start, stop and incremental feeding operation tests are carried out at medium speed;

(4) tool change test, the tool library is filled with tools, which should contain the maximum quality of the tool, automatic tool change test in an optional way, not less than 5 times. The maximum mass of the tool should also be tested at each cutter position;

(5) for machine tools with exchange table, exchange test of the exchange table for no less than 5 times;

⑥ Test the functions of coordinate linkage, positioning, linear and circular interpolation of machine tools.

3. Continuous no-load operation

Continuous no-load operation shall be carried out for not less than 8 hours after no-load operation and functional test. At this time, a continuous air operation test program can be compiled, which includes:

(1) spindle low, medium and high speed forward, reverse, quasi stop;

② The operating components on each coordinate axis run in low, medium and high feed speeds and in fast forward and reverse directions. Operation should be close to the maximum processing range, and choose any point for positioning. It is not allowed to use multiplier switch in operation. Feed speed at high speed and fast running time should not be less than 10% of the time used in each cycle program;

(3) The tool on each knife position in the knife library should be automatically changed for no less than 2 times;

Indexing table and CNC rotary table automatic indexing, positioning;

⑤ All coordinate axes operate in linkage;

⑥ Switching table automatic switching not less than 5 times;

⑦ Other functional tests;

⑧ the suspension time between cycle procedures does not exceed 0.5min.

4. Conformity test

Including bearing workpiece maximum mass test, maximum cutting torque test, maximum cutting resistance test and maximum cutting power test.

① Maximum mass test of bearing workpiece. During the test, the maximum weight of the workpiece can be placed on the workbench, so that the load is evenly distributed. Then run at minimum and maximum feed speed and fast. In the operation of the lowest feed speed, the reciprocating movement should be near the two ends and the middle of the stroke, each moving distance is not less than 20mm, for the highest feed speed and fast operation, should be carried out in the whole process, reciprocating 1 and 5 times respectively. High speed operation should be stable, low speed without crawling.

② Maximum torque test of main drive system. Generally use end milling cutter or carbide cutter to cut gray cast iron during the test. Choose a revolution in the range of constant spindle torque speed regulation, adjust the cutting amount, so that it reaches the maximum torque specified in the design, the machine should work smoothly.

Maximum cutting resistance test. The end milling cutter or twist bit is used in the test, and the workpiece material is gray cast iron. Choose an appropriate spindle speed less than or equal to the machine tool design speed range, adjust the cutting amount to achieve the design of the maximum cutting resistance. All parts of the machine should work normally and overload safety device should be sensitive and reliable.

(4) maximum power test of main transmission system. The end milling cutter is used in the test, and the specimen is steel or cast iron. Select an appropriate speed within the constant power speed regulation range of the spindle, adjust the cutting dosage to reach the maximum power (the main motor reaches the rated power), and the machine tool is required to work normally without chatter.

The program used in the trial run is called test machine program, which can be used directly when machine tool plant debugging test machine program or make a program. Test machine procedures should include: the main numerical control system function use, automatic replacement, access to the knife library in 2/3 of the tool, the spindle of the highest, lowest and commonly used speed, fast and commonly used feed speed, the table surface automatic exchange, the use of M host instructions. During the test run, the tool store of the machine tool should be filled with handles, the quality of the handle should be close to the specified quality, and the load should be added to the exchange table. During the trial run time, machine tools are not allowed to have faults except those caused by operation errors, otherwise it indicates that there are problems in machine tool installation and debugging.

For electromechanical integration design of small machine tools, its overall rigidity is very good, there are no requirements for the foundation, and after the machine to the installation, also do not have to go to assembly or any connection. Say commonly, want to connect power supply only, after adjusting the level of good bed body, can put into use