What had to be solved
The task was to create an industrial mobile complex that can be installed on rails in a depot and machine a wheelset without removing it from the locomotive or wagon.
Projects / Special equipment and demanding operating conditions
Mobile CNC wheel-lathe control system
Mobile CNC wheel-lathe complex for railway wheelsets: mechanics, control cabinet, STM32 CNC controller, Qt operator software, remote pendant and rotation power unit.
What the project reached
The project was brought to an industrial prototype and pilot operation. The solution is covered by Russian utility-model patent RU 180336 U1.
Project materials
Photos and working materials
Public materials
Engineering context
Important constraints
The equipment works in repair-depot conditions.
The machine controls four feed axes: X1, Y1, X2 and Y2.
The left and right wheels of one wheelset can be machined synchronously.
Operator workflow includes manual modes, safety logic, reports and repeatable setup procedures.
The project combines mechanics, power electronics, embedded control and desktop operator software.
Work done
What was included
Machine mechanics, production materials and documentation package.
Control cabinet, connection of drives, sensors and safety circuits.
STM32 CNC controller with a GRBL-based firmware adapted for four axes.
C++/Qt operator software with touchscreen workflow, G-code generation and reporting.
Remote pendant for manual movement and machine-control operations.
Inverter-based wheelset-rotation unit with external encoder feedback.
Commissioning support and pilot operation in repair-depot conditions.
Details
Engineering project description
System architecture
The complex consists of two mechanical machine sections with tool carriages, a control cabinet, a CNC controller, touchscreen operator software, a remote pendant, a reporting system and a separate inverter unit for rotating the wheelset.
The machine is installed directly on the rail track under a locomotive or wagon and is fixed to the rails. The design had to account for real depot conditions: metal chips, moisture, coolant and mechanical impacts were important constraints for the protection of guides and moving parts.
Mechanics and four feed axes
The mechanical part is split into left and right base frames. Each side has its own carriage with longitudinal and transverse feed. The four controlled axes X1, Y1, X2 and Y2 make it possible to set different cutting depths for the left and right wheel and machine both wheels of one wheelset at the same time.
- linear guides, ball screws, servo drives, gearboxes and belt transmissions
- rail fixation using clamps, stops and spacer elements
- protection of guides and screws from chips, moisture and mechanical impact
- production package with 3D model, parts, specifications and drawings
CNC controller and operator software
A custom STM32-based CNC controller was developed for the machine. The firmware is based on GRBL 1.1, ported and adapted for four axes.
The C++/Qt operator software stores profiles and jobs, checks machining parameters, builds the G-code program, shows coordinates and trajectories, controls start, pause, stop and manual movements, and generates reports after the operation.
Trajectory generation
The operator does not write G-code manually. The software builds the motion program from the selected profile, operation mode, bypass direction, feed, cutting depth and wheel parameters.
- full-profile machining
- removal of circular build-up
- flange machining
- roughing and finishing passes
- working-area limit checks
Machining workflow
The operator installs the machine, fixes it on the rails, connects cables, references the axes, starts wheelset rotation, brings the carriages into position and sets machining parameters. During automatic operation the screen shows the trajectories, coordinates, feed rate, active pass and execution state.
After machining, the operator can make control measurements and either finish the job with a report or return to an additional pass without losing the current coordinate and referencing state.
Remote pendant
The remote pendant allows the operator to select an axis, move the carriage, change movement coefficient, control feed, start and stop execution, pause the program, switch coordinate displays and control wheelset rotation.
Wheelset-rotation power unit
A separate inverter-based unit was developed to rotate the wheelset during machining. It maintains the required rotational speed using an external encoder pressed against the wheel rim. The module includes enclosure materials, power circuitry, controller circuitry, firmware and production files.
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