I. After running for a while during construction, the floor grinding machine has stopped. Possible reasons include:

1. Check the numbers and letters displayed on the digital screen of the machine’s armrest:

(1) If "E.LU1" is displayed, it indicates input undervoltage—meaning the grid voltage is too low. "E.LU2" signifies undervoltage during operation. In either case, you can only restart and use the machine once the voltage returns to normal; this situation typically occurs infrequently.

(2) If "EiLF" appears, it indicates a phase-loss condition. In this case, you should first check the input power cable, ensuring that none of the live wires connected to the wall or site power box are loose. Next, verify whether any of the three live wires at the power box’s wiring terminals are disconnected. Finally, inspect the power cord’s plug—make sure it’s securely inserted into the power outlet or the socket on the floor grinder’s electrical control box. If any of these connections are loose, address them one by one by reconnecting the cables properly.

2. Check the digital display on the handrail frame. If "EOL2" appears, it indicates that the motor is overloaded. This overload occurs because the grinding disc beneath the motor—located in the gearbox—experiences excessive resistance during the floor-grinding process, exceeding the motor’s torque capacity. As a result, the variable frequency drive detects that the circuit current has surpassed its rated value, triggering an overload alarm. Consequently, the VFD immediately stops outputting voltage, causing the motor to shut down instantly. In essence, the VFD issues an overload command, prompting the motor to stop as a self-protective measure. At this point, lift the machine slightly and inspect whether the number of grinding segments on the disc is too coarse (i.e., too large). Also, assess whether the floor surface is excessively uneven or deeply pitted. If so, you can replace the grinding segments with finer ones for smoother finishing. If this issue arises specifically when grinding marble, consider replacing the grinding segments on the floor grinder disc with wider, harder (thicker) segments designed for more effective debris removal. Additionally, remove any heavy iron weights or sandbags positioned above the floor grinder—these can be hung from the handrail instead—to reduce the overall grinding pressure on the disc.

2. Issues arising during the floor grinding process due to human factors include:
 

1. When the floor grinder's lifting grinding disc spins freely without load, it may rotate smoothly at first, though you might hear a slight metallic clanging sound. However, as soon as the machine is placed back on the ground and started, it immediately jams. At the same time, the digital display shows "EOL2," indicating that the metal cutting blades mounted on the grinder disc are incompatible. Some grinder discs (magnetic type) come with side-mounted three-hole metal blades—specifically, the three fixed mounting holes are positioned along one side of the blade's central axis. Yet, if you mistakenly install either the center-three-hole or center-two-hole metal blade segments during assembly, these oversized blades will protrude beyond the outer edge of the disc. As the disc rotates against the floor for grinding, the larger central (or second-central) hole in the blade segment creates excessive clearance, causing the blade to shift sideways. This misalignment leads to the grinding discs interfering with each other and eventually jamming due to mutual collisions—commonly referred to as the discs "fighting." It’s important to note, however, that this "fighting" phenomenon is actually caused by improper blade installation, not by any inherent issue with the grinding discs themselves. The real problem arises when the bearings on the gear shaft above the disc are damaged, or when the gearbox runs dry without lubrication, leading to severe gear wear and eventual failure.

2. During the grinding process, the floor grinder tends to drift to one side, indicating imbalance. Additionally, the three grinding segments on a single grinding disc show uneven wear. This issue is often caused by deformation or cracking of the shock-absorbing rubber pads located at the top of the grinding disc, which prevents the machine’s weight and pressure from being evenly distributed through the three-claw head to the disc. As a result, the disc experiences uneven force distribution, leading to inconsistent grinding pressure across the segments and, consequently, uneven wear and varying thicknesses among them. The effective solution is to replace the shock-absorbing rubber pads. There’s also another scenario: when grinding concrete floors, the floor grinder may accidentally come into contact with expansion screws embedded in the ground, causing the screws that secure the shock-absorbing pads to the three-claw head to bend or deform. This misalignment disrupts the evenness of the four grinding discs, resulting in uneven force distribution during operation. In such cases, it’s also necessary to replace the shock-absorbing pad fixing screws.