Machining the casings of large reverse-reduction gearboxes and step-down gears

The machining operations are performed on cast iron FT 25, which is the material of our transmission casings.

The choice of horizontal machining centers is due to the fact that we have to machine aligning bores on 2 opposite sides.

The casings are mainly composed of 2 or 3 parts (lower, middle, and upper casing), depending on the type of gearbox.

Principles of casing machining:

  • Each part is machined separately, usually on one side, to define 1 or 2 mating surfaces (i.e. the interface portions where the casing parts meet).
  • Then the casing parts are assembled.
  • Then the “bore lines” are machined (with the casing parts locked together to make sure of the accuracy of the bores), and various tapped holes are cut for the attachment of the different auxiliary and accessory components (fittings, pumps, supports, etc.)

For our biggest gearbox (“20000” series), the total machining time of all 3 parts is approximately 25 hours (not including set-up and adjustment).

Finishing the bore lines of these “20000” series casings takes 16 hours. This operation requires some 50 tools.

The biggest bore diameter is 480 H7 mm.

A very high degree of dimensional precision (here: tolerance H7) and geometric accuracy (trueness of the various bores and bore lines) is essential for the final assembly.

The section is comprised of 3 machines

Vertical machining center MAZAK V12 with NIKKEN divider.

The table measures 1,240 mm x 505 mm.

Maximum stroke is 1,016 mm along the X-axis, 500 mm along the Y-axis, and 500 mm along the Z-axis.

It has a FANUC 6MA enclosure for small parts machining operations (accessory components attached to the main casing: flanges, bell-housing, pump body, etc.)

It is used to drill the through holes for the bolts in the coupling flange and mating flange…

…or to remove teeth from, or bore holes into hollow drive pinions and clutch hubs, among others.

  • Horizontal machining center FRITZ WERNER TC 3.10 K

    • This machine has 2 pallets of 1,000 mm x 1,000 mm each.
    • Its maximum stroke is 2,000 mm along the X-axis, 1,250 mm along the Y-axis, and 1,100 mm along the Z-axis.
    • It carries 144 tools.
    • Its electric enclosure and control is SIEMENS SINUMERIK 850 DI.

  • Horizontal machining center TOYODA FH 80 II

    • This center has 2 pallets of 800 mm by 800 mm each.
    • Its maximum stroke is 1,350 mm along the X-axis, 1,150 mm along the Y-axis, and 1,150 mm along the Z-axis.
    • It holds 120 tools.
    • Its electric enclosure and control is FANUC 16 I

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