Boring and Milling Power Heads for High-Precision Machining
An overview of a boring and milling power head's spindle, ram, feed, hydraulic transmission, balancing cylinder, and operating principle, with a focus on precision, productivity, and flexibility.
JNYO boring and milling power heads are machine-tool attachments that provide the rotary power and controlled movement required for boring, milling, drilling, and related operations. An internal transmission system converts input rotation into the required tool rotation and feed movement.
Structure and operating principle
1. Spindle assembly
The spindle uses a BT50 taper bore with a pull-stud clamping arrangement. A shared oil-pump station may be used where the machine design permits it. Two pressure-oil lines at the pressure specified by the machine design—often around 20–30 kgf/cm² for this type of clamping circuit—can be used for tool clamping and unclamping. Always confirm pressure, connections, and tooling requirements against the equipment specification.
2. Ram assembly
The square ram moves vertically inside the spindle housing. Its guide surfaces are finished to support smooth vertical travel while maintaining the rigidity required for machining.
3. Feed mechanism
The ram feed is driven by a φ63 × 8 ball screw. A feed gearbox is mounted on the housing, and the ball-screw end is connected through a reduction arrangement to a servo motor selected for the machine configuration.
4. Main drive gearbox
The gearbox provides two speed ranges, a high range and a low range. Hydraulic shifting is supplied by the machine hydraulic station, and a two-position, four-way solenoid valve changes the cylinder direction to select the required range.
5. Balancing cylinders
Two balancing cylinders support the ram on both sides and compensate for the difference in load as the ram moves vertically. The cylinders are supplied by the machine hydraulic station according to the equipment design.
6. Power transmission
The power head uses gears and related transmission elements to convert input rotation into controlled rotary and axial movement. The spindle drives the gears, and the gear-and-rack relationship provides the required feed movement for the machining process.
Performance advantages
- Precision: Supports accurate boring and milling when correctly configured, installed, and maintained.
- Productivity: Helps complete machining operations efficiently and can reduce the number of separate setups.
- Flexibility: Supports boring, drilling, hole enlargement, and milling with suitable cutters, boring bars, or milling holders.
A boring and milling power head should be selected with the machine layout, workpiece, tooling, hydraulic circuit, and cutting conditions in mind. Correct installation and maintenance are essential for achieving the intended performance.
