1.1 Installation of CNC machine tool body
1. Before a CNC machine arrives, the user should prepare its installation according to the manufacturer's foundation drawing, leaving holes for anchor bolts. After arrival, commissioning personnel should follow unpacking procedures and move the components to the installation site. Position the major components on the foundation as instructed in the manual. Place support shims, leveling blocks and anchor bolts in their designated positions, then assemble the components into the complete machine. After assembly, connect electrical cables, oil lines and air lines.
There are electrical wiring diagrams and pneumatic and hydraulic pipeline diagrams in the machine tool manual. Accordingly, the relevant cables and pipes should be connected one by one according to the marks.
2. Precautions at this stage are as follows.
1) After unpacking the machine tool, first find the random documents, find the machine tool packing list, and check whether the components, cables, materials, etc. in each box are complete according to the packing list.
2) Before assembling each component of the machine tool, first remove the anti-rust paint on the mounting connection surface, guide rails and each moving surface, and clean the appearance of each component.
3) When connecting, pay special attention to cleanliness and reliable contact and sealing, and check for looseness and damage. After plugging in the cable, be sure to tighten the fastening screws to ensure reliable contact. When connecting oil pipes and air pipes, special precautions should be taken to prevent foreign matter from entering the pipes from the interfaces and causing failure of the entire hydraulic system. Each joint must be tightened when connecting the pipes. After the cables and pipelines are connected, each pipeline must be fixed in place and the protective cover installed to ensure a neat appearance.
1.2 CNC system connection
1) Unpacking inspection of CNC system.
Whether it is a CNC system purchased individually or a CNC system purchased as a complete machine tool, it should be carefully inspected after it arrives and is unpacked. The inspection includes the system body and its supporting feed speed control unit and servo motor, spindle control unit and spindle motor.
2) external cable connection.
External cable connections refer to the connections between the control system and external MDI/CRT units, strong power cabinets, machine tool operation panels, feed servo motor power lines and feedback lines, spindle motor power lines and feedback signal lines, and connections with hand-operated pulse generators, etc. These cables should be made in accordance with the connection manual supplied with the machine and should be connected to the ground wire at the end.
3) CNC system power cord connection.
Connect the input cable of the CNC system power supply while turning off the power switch of the CNC cabinet.
4) setting confirmation.
There are many set points short-circuited with jumper wires on the printed circuit board in the CNC system, which need to be set appropriately to adapt to the different requirements of various types of machine tools.
5) Confirm input power supply voltage, frequency and phase sequence.
Various CNC systems have DC stabilized power supplies inside to provide the system with the required DC voltages of ±5V, 24V, etc. Therefore, before powering on the system, the loads of these power supplies should be checked for short circuit to ground. Use a multimeter to confirm.
6) Confirm whether the voltage output terminal of the DC power supply unit is short-circuited to ground.
7) Turn on the power supply of the CNC cabinet and check the output voltages.
Before turning on the power, to ensure safety, disconnect the motor power line first. After turning on the power, first check whether each fan in the CNC cabinet is rotating to confirm whether the power is turned on.
8) Confirm the settings of each parameter in the CNC system.
9) Confirm the interface between the CNC system and the machine tool side.
After completing the above steps, it can be considered that the CNC system has been adjusted and has the conditions to be connected to the machine tool for power-on test. At this time, you can cut off the power supply of the CNC system, connect the power line of the motor, and restore the alarm setting.
1.3 CNC machine tool power-on experiment
According to the instructions of the CNC machine tool, lubricate the machine tool and fill the lubrication points with the specified oil and grease, clean the hydraulic oil tank and filter, fill in the specified grade of hydraulic oil, and connect the external air source.
A machine tool can be powered up by supplying all sections at once, or by powering each component separately before testing the complete power supply. When the CNC system and machine tool are connected and powered up for a trial run, even if the CNC system has been confirmed to function normally without alarms, the operator should still be ready to press the emergency stop button as power is applied so that power can be cut at any time. When checking the operation of each axis, move the axes using manual continuous feed and use the values shown on the CRT or DPL (digital display) to verify that machine components move in the correct directions.
Then check whether the travel distance of each axis matches its movement command. If it does not, check the relevant commands, feedback parameters and settings such as the position control loop gain. Next, move each axis slowly using manual feed until it actuates the overtravel switch, checking that the overtravel limit works and that the CNC system issues an alarm on overtravel. Carefully check that parameter settings in the CNC system and PMC unit match the values specified in the documentation supplied with the machine. Then test whether the various operating modes (manual, jog, MDI, automatic, etc.), spindle gear-change commands and speed commands at all levels operate correctly.
Finally, a return to the reference point should be performed. The reference point of the machine tool is the program reference position for subsequent processing by the machine tool. Therefore, it is necessary to check whether there is a reference point function and whether the position returned to the reference point is completely consistent each time.
1.4 Installation and adjustment of CNC machine tools
According to the CNC machine tool manual, roughly check whether the main components of the machine tool are functioning normally and completely, so that all aspects of the machine tool can operate and move. Adjust the bed level of the machine tool, roughly adjust the main geometric accuracy of the machine tool, and then adjust the relative position of the reassembled main moving parts and the main machine. Use quick-drying cement to pour the anchor bolts of the main machine and various accessories, fill in each reserved hole, and wait until the cement is completely dry.
On the cured foundation, use anchor bolts and leveling shims to fine-adjust the level of the machine tool's main bed. After leveling, move the bed's moving components, including the main column, slide, and worktable, observe changes in machine level throughout the full travel of each coordinate axis, and adjust geometric accuracy accordingly to keep it within the allowable error range. Measuring tools used for adjustment include precision levels, standard square rulers, straightedges, and collimators. Adjustment should mainly be made through the leveling shims, with slight changes to guideway gibs and preloaded rollers where necessary.
1.5 The tool changer of the machining center is running
Let the machine tool automatically move to the tool exchange position (programs such as G28 Y0 Z0 or G30 Y0 Z0 can be used), and manually adjust the positions of the tool loading manipulator and tool unloading manipulator relative to the spindle. During the adjustment, a calibration mandrel is used for detection. If there is an error, the robot's stroke can be adjusted, the robot support and the tool magazine position can be moved. If necessary, the setting of the tool change position point can also be modified (change the parameter settings in the CNC system).
After the adjustment is completed, tighten the adjustment screws and the tool magazine anchor bolts, then install several tool handles close to the specified allowable weight, and perform multiple automatic exchanges from the tool magazine to the spindle. The movement is required to be accurate without impact or drop of the tool.
For machine tools with APC exchange worktables, the worktable needs to be moved to the exchange position, and the relative position of the pallet station and the exchange table should be adjusted to achieve smooth, reliable and accurate movement of the worktable during automatic tool change. Then install the allowable load of 70~80% on the work surface, perform multiple automatic exchange actions, and then tighten the relevant screws after reaching accuracy.
1.6 CNC machine tool trial operation
After the CNC machine tool is installed and debugged, the whole machine is required to run automatically for a long period of time under a certain load condition to comprehensively check the machine tool function and working reliability. There is no unified regulation on the running time. Generally, it is used to run 8h every day and continuously run 2 to 3 days; or 24h to run continuously for 1 to 2 days. This process is called a post-installation commissioning.
The acceptance test program should include use of the main CNC system functions, automatic tool changes using 2/3 of the tools in the magazine, maximum, minimum and commonly used spindle speeds, rapid and commonly used feed rates, automatic table exchange, and use of the main M commands. During the trial run, the tool magazine should be filled with toolholders, and the selected toolholders should weigh close to the specified allowable weight. Loads should also be placed on the exchangeable tables. No machine faults are permitted during the trial run except those caused by operator error. Any other fault indicates a problem with installation or commissioning.
1.7 Acceptance of CNC machine tools
After the machine tool debugger completes the installation and debugging of the machine tool, the acceptance work of the CNC machine tool user is to partially or fully measure the various technical indicators on the machine tool certificate through the testing methods that can be actually provided according to the acceptance conditions specified on the machine tool factory inspection certificate. The acceptance results after passing the inspection will be used as the basis for technical indicators for future maintenance. The main acceptance work is as follows.
1) Machine tool appearance inspection. Before conducting detailed inspection and acceptance of CNC machine tools, inspection and acceptance of the appearance of the CNC cabinet should include the following aspects.
① Appearance inspection: Use the naked eye to check whether each unit in the CNC cabinet is damaged or contaminated, whether the connecting cable bundle is damaged, and whether the shielding layer is peeling off.
② Inspection of the tightening conditions of components within the CNC cabinet: including screw tightening inspection, connector tightening inspection, and printed circuit board tightening inspection.
③ Appearance inspection of the servo motor: In particular, the casing of the servo motor with a pulse encoder should be carefully inspected, especially its rear end.
2) Machine tool performance and NC function test. Now take a vertical machining center as an example to illustrate some main inspection items.
① Spindle system performance.
②Feeding system performance.
③ Automatic tool changing system.
④ Machine tool noise. The total noise during idle operation of the machine tool shall not exceed 80dB.
⑤ Electrical devices.
⑥ Digital control device.
⑦ Safety device.
⑧ Lubrication device.
⑨ Gas and liquid devices.
⑩ Accessories.
⑩ Accessories.
(11) CNC function.
(12) Continuous no-load operation.
3) Machine tool geometric accuracy check. The geometric accuracy of CNC machine tools comprehensively reflects the geometric shape errors of the key mechanical components and assembly of the equipment. The following lists the geometric accuracy testing content of an ordinary vertical machining center.
① Flatness of the work surface.
② The mutual perpendicularity of movement in each coordinate direction.
③ Parallelism of the work surface when moving in the X coordinate direction.
④ Parallelism of the work surface when moving in the Y coordinate direction.
⑤ Parallelism of the T-shaped groove side of the work surface when moving in the X coordinate direction.
⑥ Axial movement of the spindle.
⑦ Radial circular runout of the spindle hole.
⑧ Parallelism of the spindle axis when the spindle box moves along the Z coordinate direction.
⑨ The verticality of the spindle rotation axis to the work surface.
⑩ The straightness of the spindle box movement in the Z coordinate direction.
4) Machine tool positioning accuracy check. It indicates the accuracy that the measured moving parts of the machine tool can achieve under the control of the CNC device. The main inspection contents of positioning accuracy are as follows.
① Linear motion positioning accuracy (including X, Y, Z, U, V, W axes).
② Repeatable positioning accuracy of linear motion.
③ Return accuracy of the mechanical origin of the linear motion axis.
④ Determination of the amount of lost momentum in linear motion.
⑤ Rotary motion positioning accuracy (turntable A, B, C axes).
⑥ Repeatable positioning accuracy of rotary motion.
⑦ Return accuracy of the rotary axis origin.
⑧ Measurement of the amount of motion loss of the return axis.
5) Machine tool cutting accuracy inspection. The essence of machine tool cutting accuracy inspection is a comprehensive assessment of the geometric accuracy and positioning accuracy of machine tools under cutting and processing conditions. In China, single-item processing is the main focus. For the machining center industrial automation network, the main individual accuracy is as follows.
① Boring accuracy.
② Accuracy of the milling plane of the end mill (X-Y plane).
③ Hole spacing accuracy and hole diameter dispersion of boring holes.
④ Linear milling accuracy.
⑤ Oblique line milling accuracy.
⑥ Arc milling accuracy.
⑦ Coaxiality of box U-turn boring (for horizontal machine tools).
⑧ Horizontal turntable rotation 90° square milling accuracy (for horizontal machine tools).
(Source: CNC Preface)