Schiess K Vertical boring and turning mills

Schiess  Vertical Boring and Turning Machine: Type K

Constructional Details

Details of the construction of the vertical boring and turning machine, Type K, can be seen in Fig. 2. The two columns, ribbed for extra ruggedness, together with the cross brace and base assembly, form a self-constrained, rigid frame construction, as shown in Fig. 3. The cross rail and the right-hand column mount the horizontally and vertically traversable heads. Bronze liners are fitted in the cross rail and heads to improve the sliding properties and are automatically lubricated during traverse, either in relation to time or movement.

There are two pendant push-button stations and a stationary control desk for operating the machine.

Drive

Drive to the table is obtained from an infinitely variable-speed DC motor with Ward-Leonard converter in conjunction with an electro-hydraulically actuated 4-speed range transmission. This drive provides a stepless speed variation in each speed range, with preselection by means of push buttons. If desired, the Ward-Leonard drive can be provided with an automatic speed control which, for facing work, will keep the cutting speed approximately constant in relation to the horizontal feed of either rail head. A constant-speed three-phase AC motor with a 20-speed transmission can be installed instead of the DC motor. The individual speeds can be preselected electronically and are engaged electro-hydraulically. With either type of drive, the direction of table rotation is reversible.

Lubrication

The hydrostatic table is a ring which is covered by a German patent (No. 1,477,943) and various foreign patents. Oil is fed under pressure by a symmetrically placed pump to all the chambers, so that the table is constantly carried on a film of lubricant. The advantages of the hydrostatic over the hydrodynamic type are mixed friction at low speeds is eliminated; track wear is avoided; heat generation is reduced; and the efficiency of the table drive is increased.

A large-diameter table can be furnished with an additional thrust bearing under the king spindle, hydraulically adjustable to accommodate heavy central loading of the table. All tables have a pre-loaded cylindrical roller bearing. All bearings are meticulously examined in a fully air-conditioned inspection shop and are required to undergo precision tests.