Installation, commissioning and acceptance of CNC machine tools

1.1 Installation of CNC machine tool body

1. Before the arrival of the CNC machine tool, the user should prepare for installation according to the machine tool foundation drawing provided by the machine tool manufacturer, and make reserved holes at the location where the anchor bolts are installed. When the CNC machine tool is delivered, the commissioning personnel will transport the machine tool components to the installation site according to the unpacking procedures, and put the major components of the machine tool in place on the foundation according to the instructions. When in place, the shims, adjustment pads and anchor bolts should be placed in the right positions, and then the various parts of the machine tool should be assembled into a complete machine. After the parts are assembled, the cables, oil pipes and air pipes should be connected. There are electrical wiring diagrams and gas and hydraulic pipeline diagrams in the machine tool manual. The relevant cables and pipelines should be connected one by one according to the marks.

2. The precautions for this stage are as follows.

1) After unpacking the machine tool, first find the random documents and find the machine tool packing list, and check whether the parts, cables, and materials in each packaging box are complete according to the packing list.

2) Before assembling the machine tool components, first remove the anti-rust paint on the installation connection surface, guide rails and moving surfaces, and clean the surface of each component.

3) When connecting, pay special attention to cleaning and reliable contact and sealing, and check for looseness and damage. After the cable is plugged in, be sure to tighten the fixing screws to ensure reliable contact. When connecting the oil pipe and air pipe, be especially careful to prevent foreign matter from entering the pipeline from the interface, causing the entire hydraulic system to malfunction. When connecting the pipeline, each joint must be tightened. After the cable and pipeline are connected, the pipelines must be fixed in place and the protective cover must be installed to ensure a neat appearance.

1.2 Connection of CNC system

(1) Unpacking inspection of CNC system.

Whether it is a single CNC system purchased or a CNC system purchased as a complete machine, it should be carefully inspected after arrival. The inspection includes the system body and the matching feed speed control unit and servo motor, spindle control unit and spindle motor.

(2) Connection of external cables.

External cable connection refers to the connection between the CNC system and the external MDI/CRT unit, the power cabinet, the machine tool operation panel, the feed servo motor power line and feedback line, the spindle motor power line and feedback signal line, and the hand-cranked pulse generator. These cables should comply with the provisions of the connection manual provided with the machine, and the ground wire should be connected at the end.

(3) Connection of the CNC system power line.

Connect the input cable of the CNC system power supply with the power switch of the CNC cabinet turned off.

(4) Confirmation of settings.

There are many setting points on the printed circuit board in the CNC system that are short-circuited with jumper wires. They need to be properly set to meet the different requirements of various machine tools.

(5) Confirmation of input power supply voltage, frequency and phase sequence.

Various CNC systems have internal DC regulated power supplies to provide the system with the required DC voltages such as ±5V and 24V. Therefore, before the system is powered on, check whether the loads of these power supplies are short-circuited to the ground. A multimeter can be used to confirm.

(6) Confirm whether the voltage output terminal of the DC power supply unit is short-circuited to the ground.

(7) Turn on the power of the CNC cabinet and check the output voltages.

Before turning on the power, disconnect the motor power line to ensure safety. After turning on the power, first check whether the fans in the CNC cabinet are rotating to confirm whether the power is on.

(8) Confirm the settings of the parameters of the CNC system.

(9) Confirm the interface between the CNC system and the machine tool.

After completing the above steps, it can be considered that the CNC system has been adjusted and is ready for online power-on test with the machine tool. At this time, cut off the power of the CNC system, connect the power line of the motor, and restore the alarm setting.

1.3 Power-on test of CNC machine tools

According to the requirements of the CNC machine tool manual, lubricate the machine tool, 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 input air source.

The power-on operation of the machine tool can be to power all parts at once, or to power each component separately, and then do a total power supply test. When the CNC system and the machine tool are connected and powered on for test run, although the CNC system has been confirmed to be working normally without any alarm, you should still be prepared to press the emergency stop button while the power is turned on to cut off the power at any time. When checking the operation of each axis of the machine tool, use manual continuous feed to move each axis, and check whether the movement direction of the machine tool parts is correct through the display value of CRT or DPL (digital display).

Then check whether the movement distance of each axis is consistent with the movement instruction. If not, check whether the relevant instructions, feedback parameters, and position control loop gain and other parameter settings are correct. Subsequently, use manual feed to move each axis at a low speed and make them hit the overtravel switch to check whether the overtravel limit is effective and whether the CNC system issues an alarm when overtravel. Carefully check whether the parameter setting values ​​in the CNC system and PMC device are consistent with the specified data in the random data, and then test various operation modes (manual, inching, MDI, automatic mode, etc.), spindle shift instructions, various levels of speed instructions, etc. are correct. Finally, a return to reference point action should be performed. The reference point of the machine tool is the program reference position for the machine tool to process in the future. Therefore, it is necessary to check whether there is a reference point function and whether the position of the reference point returned each time is completely consistent.

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 normal and complete, so that all aspects of the machine tool can be operated and moved. 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 the reserved holes flat, and wait for the cement to completely dry.

Use anchor bolts and shims to fine-tune the level of the main bed of the machine tool on the solidified foundation. After finding the level, move the moving parts on the bed (main column, slide and workbench, etc.), observe the horizontal transformation of the machine tool within the full stroke of each coordinate, and adjust the geometric accuracy of the machine tool accordingly to make it within the allowable error range. The detection tools used in the adjustment include precision level, standard square ruler, flat ruler, parallel light tube, etc. During adjustment, the main focus is on adjusting the shims. If necessary, the inserts and preload rollers on the guide rails can be slightly changed.

1.5 Operation of the tool changer in the machining center

Let the machine tool automatically move to the tool exchange position (G28 Y0 Z0 or G30 Y0 Z0 and other programs can be used), and the positions of the tool loading and unloading manipulators relative to the spindle are adjusted manually. During the adjustment, a calibration mandrel is used for detection. If there is an error, the manipulator stroke can be adjusted, the manipulator support and the tool magazine position can be moved, and the tool change position point setting can be modified if necessary (the parameter setting in the CNC system can be changed). After the adjustment is completed, tighten the adjustment screws and the tool magazine anchor bolts, and then install several tool holders close to the specified allowable weight, and perform multiple reciprocating automatic exchanges from the tool magazine to the spindle. The action must be accurate, without collision or tool drop.

For machine tools with APC exchange tables, the table must be moved to the exchange position, and the relative position of the pallet station and the exchange table surface must be adjusted to achieve smooth, reliable and accurate action when the table automatically changes tools. Then, install 70-80% of the allowable load on the work surface, perform multiple automatic exchange actions, and tighten the relevant screws after reaching accuracy.

1.6 CNC machine tool trial operation

After the installation and commissioning of the CNC machine tool is completed, the whole machine is required to automatically run for a long time under certain load conditions 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 8 hours a day, continuously run for 2-3 days; or 24 hours continuously for 1-2 days. This process is called the trial operation after installation.

The assessment procedure should include: the use of the functions of the main CNC system, automatic replacement of 2/3 of the tools in the tool magazine, the highest, lowest and commonly used speeds of the spindle, fast and commonly used feed speeds, automatic exchange of the work surface, and the use of the main M instructions. During the trial operation, the machine tool magazine should be filled with tool holders, the weight of the tool holder should be close to the specified allowable weight, and the exchange work surface should also be loaded. During the trial operation period, except for the faults caused by operating errors, no machine faults are allowed to occur, otherwise it indicates that there are problems with the installation and commissioning of the machine tool.

1.7 Acceptance of CNC machine tools

After the machine tool commissioning personnel complete the installation and commissioning of the machine tool, the acceptance work of the CNC machine tool user is to partially or completely measure the various technical indicators on the machine tool certificate according to the acceptance conditions specified in the machine tool factory inspection certificate through the actual detection means that can be provided. After passing the acceptance, the acceptance results will be used as the basis for technical indicators for future maintenance. The main acceptance work is as follows.

1) Appearance inspection of the machine tool. Before the detailed inspection and acceptance of the CNC machine tool, the appearance of the CNC cabinet should be inspected and accepted, which should include the following aspects.

① Appearance inspection: Use the naked eye to check whether the units in the CNC cabinet are damaged or contaminated, whether the connecting cable bundle is damaged, and whether the shielding layer is peeling off.

② Inspection of the tightness of the components in the CNC cabinet: including screw tightness inspection, connector tightness inspection, and printed circuit board tightness inspection.

③ Surface inspection of servo motor: In particular, the housing of servo motor with 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 explain some major inspection items.

① Spindle system performance.

② Feed system performance.

③ Automatic tool change system.

④ Machine tool noise. The total noise of the machine tool during idling shall not exceed 80dB.

⑤ Electrical device.

⑥ Digital control device.

⑦ Safety device.

⑧ Lubrication device.

⑨ Gas and liquid device.

⑩ Auxiliary device.

⑪ CNC function.

⑫ Continuous no-load operation.

3) Machine tool geometric accuracy inspection. The geometric accuracy of CNC machine tools comprehensively reflects the geometric shape errors of the key mechanical parts and components of the equipment after assembly. The following lists the geometric accuracy inspection contents of an ordinary vertical machining center.

① Flatness of the worktable.

② Mutual perpendicularity of movement in each coordinate direction.

③ Parallelism of the worktable when moving in the X-coordinate direction.

④ Parallelism of the worktable when moving in the Y-coordinate direction.

⑤ Parallelism of the side of the T-slot of the worktable when moving in the X-coordinate direction.

⑥ Axial movement of the spindle.

⑦ Radial runout of the spindle hole.

⑧ Parallelism of the spindle axis when the spindle box moves in the Z-coordinate direction.

⑨ Perpendicularity of the spindle rotation axis to the worktable surface.

⑩ Straightness of the spindle box moving in the Z-coordinate direction.

4) Machine tool positioning accuracy inspection. It indicates the accuracy that can be achieved by the measured moving parts of the machine tool 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 Linear motion repeat positioning accuracy.

③ Return accuracy of the mechanical origin of the linear motion axis.

④ Determination of the amount of lost momentum in linear motion.

⑤ Positioning accuracy of rotary motion (rotary table A, B, C axis).

⑥ Repeated positioning accuracy of rotary motion.

⑦ Return accuracy of the origin of the rotary axis.

⑧ Determination of the amount of lost momentum in the return axis motion.

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 the machine tool under cutting and processing conditions. Domestically, single-item processing is the main focus. For the machining center industrial automation network, the main single-item accuracy is as follows.

① Boring accuracy.

② Accuracy of the milling plane of the end milling cutter (X-Y plane).

③ Boring hole spacing accuracy and hole diameter dispersion.

④ Linear milling accuracy.

⑤ Oblique milling accuracy.

⑥ Arc milling accuracy.

⑦ Coaxiality of the box turn-around boring (for horizontal machine tools).

⑧ The horizontal turntable rotates 90° to improve the square milling processing accuracy (for horizontal machine tools).