Knowledge
The automotive intermediate shaft bearing tolerance inspection equipment is used to precisely locate the tolerance of the bearing mounting position. Its high cycle rate and high accuracy place stringent demands on signal acquisition stability. The introduction of remote I/O simplifies wiring complexity, improves signal transmission efficiency, and reduces maintenance difficulty through centralized control, providing stable assurance for the inspection process.
The Solidot products used in this case study are PN4-1616B, PN4-0032B, and PN4-0016B.
1. Production process overview
Equipment workflow: workpiece loading → gripper positioning → tolerance inspection → sorting and unloading
[Workpiece loading]
The robot transfers the intermediate shaft to the inspection station. The photoelectric sensor triggers the in-position signal and starts the clamping process.
[Gripper positioning]
The pneumatic gripper feeds back its open/close status in real time via the magnetic switch, and calibrates the shaft end reference position in conjunction with the proximity switch.
[Tolerance inspection]
The servo mechanism drives the workpiece to rotate. The laser displacement sensor scans the profile of the bearing mounting position, synchronously acquiring dynamic data via photoelectric signals, and compares it with the theoretical tolerance band in real time.
[Sorting and unloading]
The PLC controls the sorting mechanism based on the inspection result. Out-of-tolerance workpieces trigger an audible and visual alarm and are automatically rejected.
2. I/O module application mode
The equipment uses the PROFINET protocol to build the bus network, with a Siemens S7-1200 PLC as the main controller. The I/O points are distributed near the gripper unit, inspection station, and servo mechanism. The Solidot integrated I/O modules PN4-1616B, PN4-0032B, and PN4-0016B are selected for nearby deployment. The specific applications are as follows—
PN4-1616B (16-channel digital input/16-channel digital output): The 16-channel digital input acquires the synchronous trigger signal of the laser displacement sensor, receives real-time status feedback from the servo mechanism (such as home position, in-position, and alarm), and centrally acquires the gripper open/close status signal from the magnetic switch and the workpiece in-position and inspection signals from the photoelectric sensor; the 16-channel digital output controls motor start/stop and motor rotation direction (forward/reverse).
PN4-0032B (32-channel digital output): The output points control the status switching of the inspection station indicator, drive the cooling fan start/stop to ensure stable operation of the laser sensor, and control the run/stop signal of the conveyor belt.
PN4-0016B (16-channel digital output): Drives the gripper solenoid valve to perform clamping/releasing actions, links with the pneumatic valve of the sorting mechanism to execute workpiece sorting, and triggers the audible and visual alarm device in response to out-of-tolerance workpieces.
3. Solution optimization results
The customer's original solution used a Siemens PLC with local I/O expansion modules, with all electrical components centrally installed in the control cabinet, resulting in congested wiring ducts and excessively long cables. After upgrading to Solidot PROFINET integrated I/O modules, nearby deployment at the inspection station reduces cable consumption, simplifies on-site wiring, and significantly improves equipment maintenance convenience.
