Rotary spindle head (swing or fork head that tilts the milling spindle on a rotary axis)

01

One swing axis or a two-axis fork, and what drives it

Tanshing's UHP and UHM rotary spindle heads are single swing axes: the UHP uses a hypoid gear ("HP"), the UHM a worm gear ("HM"), and its code list also names a cam version ("HC"). Tanshing says the swing head "is suitable for any spindle from any brand", turns clockwise and counter-clockwise for swing-angle and multi-axis elliptic-arc machining, and clamps with a "Wholly circular hydraulic clamping system". [1]

Kessler builds two-axis heads from MINI to MEDIUM plus a Quick Axis Change version, driven by its torque motors, with a "monolithic fork" and "Secondary cooling in the C-axis reduces the heat input in the headstock to a minimum"; it also offers its own spindles for them, optionally with shaft clamping for turning. [2] Zimmermann's VH40 is a two-axis fork head in monobloc cast iron with a backlash-free drive in the A and C axes. [3]

02

Holding the angle: driven torque against clamped torque

Each head gives one torque for moving the axis under control and a higher one when the axis is clamped. Zimmermann lists 1,200 Nm on the A axis and 1,279 Nm on the C axis in control, and 3,000 Nm on both when clamped. [3] Tanshing lists clamping torque only: 833 N·m on the UHP-30, 1,764 N·m on the UHP-40 and UHM-40, 2,450 N·m on the UHP-50 at 35 kg/cm² hydraulic pressure, and 156.8 N·m on the pneumatically clamped UHM-30B at 5 kg/cm². [1]

Kessler states the spindle torque each size of head accepts: up to 200 Nm S1 on the SMALL 2AH, up to 400 Nm on the MEDIUM 2AH and up to 1,200 Nm S1 on the MEDIUM 2AH Pro. [2]

Zimmermann's C-axis entry reads "300°" alongside "Z-Axis ≥ 1.500 mm" and "360°"; ask which C-axis range applies to the machine's Z stroke. [3]

State whether the head will cut with the axes clamped at a fixed angle (3+2) or moving simultaneously, and the cutting torque at the spindle, so the maker can check driven and clamped torque against it.

03

From arc-seconds at the axis to microns at the tool tip

Zimmermann gives the VH40 a positioning accuracy of 10" and repeatability of 6" on the A and C axes, a resolution of 0.0001°, and a swivel-axis-to-spindle-nose distance of 326 mm with the 70 kW HSK-A100 spindle or 301 mm with the HSK-A63/80 spindles. [3] Tanshing gives a minimum input increment of 0.001° and leaves indexing accuracy and repeatability blank with the note that positioning accuracy depends on the encoder type; it lists the ECA-4000 encoder. [1]

Editorial calculation: 10 arc-seconds is 10 ÷ 206,265 ≈ 0.0000485 rad; at 326 mm from the pivot to the spindle nose that moves the nose about 0.0158 mm (16 µm), and at 301 mm about 0.0146 mm, before tool length is added. Repeatability of 6" at 326 mm gives about 9.5 µm. [3]

04

Rotary spindle head order details

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Axes: [single swing axis; A/B + C fork]
Tilting range: [degrees; C range]
Drive: [hypoid; worm; cam; torque motor]
Torque: [driven; clamped; cutting torque at spindle]
Spindle: [supplied or customer; interface; torque S1; speed]
Accuracy: [positioning; repeatability; encoder]
Pivot to spindle nose: [mm]
Clamping: [hydraulic or pneumatic; pressure]
Machine: [Z slide interface; control; mass limit]

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