Fig. 2.1.3 Grinding wheels included in lathes. a Vertical from Index. b Horizontal from Mazak
2.2 Turning Centers: Multi-tasking Machines
Multi-tasking machines have become the most important evolution of lathes in the last ten years, holding a privileged position in the catalogue of many leading manufacturers.
The origin of turning centers or multi-tasking machines can be found in the application of additional motorized tools, which have been used in lathes for many years. The market tendency towards lower batches, higher flexibility and the reconfigurability of machines has fostered the fast extended development of solutions in this line.
It is difficult to delimit or mark the fields of applications and the configuration of multi-tasking machines, since nowadays the variations and combinations of features, devices and processes integrated are almost infinite. The imagination and development capabilities of machine tool manufacturers have made almost any combination possible, in vertical and horizontal configurations.
The first steps in turning centers consisted of conventional lathes that included a milling head instead (or in addition to) of the turret, with one or two additional axes to perform interpolated milling operations.
Multi-tasking “turning-drilling-milling” centers with the standard B, C, X, Y and Z-axes allow the complete machining of precise complex workpieces. The goal to completely machine and measure a wide spectrum of workpieces with minimal settings in only one machine has been achieved. By the interpolation of up to five axes even free form surfaces can be machined easily. To summarize, the claims for these types of machines are:
●The reduction of floor-to-floor time. The number of machines involved in the machining process is drastically reduced. Queuing up in front of machines or transport in between individual machines is reduced to a minimum. Work scheduling and planning is extremely simplified. The cost of stock piling semi finished piece parts is reduced.
● Increased flexibility. In multi-tasking machines setup times are usually low when changing over to another clamping or piece part. Expensive, complicated fixtures are unnecessary. Due to technological capabilities, these machines offer many creative possibilities in the customer’s design department.
● Increase in use. Decreasing setup times are equivalent to a significant increase in production hours. Complete machining means machining processes are not cut by manual interventions, which eliminate interruptions by breaks.
●Reduction of manpower. The 本文来自辣,文,论#文,网,
www.751com.cn 加7位QQ324.9114找源文 , piece part transport and work scheduling. The complete machining process combines formerly individual processes in just one operation, enabling a multiple machine operation.
●Increase in quality. Due to the lack of multiple clam pings as in split manufacturing not only costs for fixturing are reduced but also clamping and adjustment errors are avoided.
These machines have progressed towards higher sizes, power capabilities and the integration of different solutions and processes. Some of the latest, most significant examples will be presented below.
3 The Latest Technologies Applied to Lathes and Turning Centers
This section summarizes the most important technologies developed to provide new machines with the performances required to satisfy increasing market demands.
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