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New Release of Swiss Type Automatic Lathe SV-20R

February 24, 2016

- ø20mm-Type Line-up in the SV Series with B-axis Control -



Star Micronics has successfully developed a new product, SV-20R, as a Swiss type automatic lathe (NOTE 1) in the SV series. This model has been developed to target the machining of complicated components in the automobile- and medical-related areas and will be put on the global market in May, 2016.

SV-20R ensures a maximum machining diameter of 20mm and has an 8-position turret-type tool post with a tool swing control axis (B-axis). The 8-position turret-type tool post can accommodate a swing-type power tool unit at a maximum of four positions to allow a flexible angle control according to the program, simultaneous 5 axis control and other machining variations.

In order to respond to the needs for more versatile component machining, the guide bush type and non-guide bush type (NOTE 2) can both be changed over. The guide bush type functions as a clamper for motor shafts and other long parts to restrict deflection of workpieces and achieve highly accurate machining. On the other hand, the non-guide bush type is chosen to machine nuts and other short parts to minimize scrap materials to be discarded and reduce material costs in order to achieve optimum specifications according to respective machining parts.

The number of controlled axes is 12 including 9 axes for linear movement, 2 axes for spindle rotation and a B axis for tool swing movement. For front working, a 2axis controlled gang-type tool post is arranged on the front side, and a 3axis controlled turret-type tool post is arranged on the rear side, with the guide bush in the center.

写真:SV-20R

Each tool post is controlled independently so that turning, drilling and milling can be performed at the same time. By dividing the processes on the front and rear sides or by simultaneously machining on both sides via an 8-spindle unit with a Y-axis control function especially designed for rear working, machining time is reduced.

In addition to the above, the unique Star Motion Control System (NOTE 3) minimizes non-cutting time needed for computing time, tool selection time, etc. during NC-controlled operation, and achieves a shortened cycle time.




♦ Features of SV-20R

[High Functionality]
  • The 8-position turret type tool post can accommodate a 2-spindle power driven tool unit for B-axis control at a maximum of four positions.
  • Either the guide bush type or non-guide bush type can be selected with a single machine according to the total length of parts to be machined.
  • The 8-spindle unit with a Y-axis control function especially for back working can accommodate a power tool unit at all positions.
[High Productivity]
  • The Star Motion Control System shortens the non-cutting time.
  • The 8-spindle back working unit with Y-axis control function realizes simultaneous machining on the front and rear sides.
  • The output of the power tool motor used for the gang-type tool post is improved (compared to Star Micronics conventional models).
[High Rigidity and High Accuracy]
  • The non-guide bush type incorporates a spindle sleeve slide guideway structure (NOTE 4) to ensure high spindle rigidity.
  • Both the main and sub spindles each use a built-in motor. A built-in sensor is also used to improve indexing accuracy.


♦ Major Specifications

Max. machining diameter ø 20mm
Max. head stock stroke Guide bush type 205mm
Non-guide bush type 50mm
Max. main spindle speed 10000 min-1
Main spindle motor 3.7kw (cont.)/5.5kw (10min./60% ED)
Max. sub spindle speed 10000 min-1
Sub spindle motor 2.2kw (cont.)/3.7kw (10min./25% ED)
Gang-type tool post Ordinary tools 6 tools(□16mm)/ 7 tools(□12mm)
Power-driven tools 5 tools
Max. spindle speed 8000 min-1
Drive motor 2.2kw
Turret-type tool post Tool mounting position 8 positions
Positions with B-axis control 4 positions
Ordinary tools Max. 3 tools/position (□12mm)
Sleeve Max. 3 tools/position
Power-driven tools Max. 2 tools/position
Max. spindle speed 5750 min-1
Drive motor 2.7kw (cont.) / 4.0kw(5min/30%ED)
8-spindle back working unit Number of tools 8 tools
Max. spindle speed 8000 min-1
Drive motor 1.0kw (cont.)/1.2kw (5min./30%ED)
Front-side machining capability [Stationary tool] Max. drilling capability ø 14mm
Max. tapping capability M10 × P1.5
[Power-driven tool] Max. drilling capability ø 10mm
Max. tapping capability M8 × P1.25
Rear-side machining capability [Stationary tool] Max. drilling capability ø 12mm
Max. tapping capability M10 × P1.5
[Power-driven tool] Max. drilling capability ø 6mm
Max. tapping capability M5 × P0.8
Machine dimensions (W x D x H) 2730 × 1350 × 1865 mm

NOTE 1: Swiss-type automatic lathe
The Swiss-type automatic lathe was devised as watch component processing machinery in Switzerland in 1870s. Known as a “sliding head-type automatic lathe” as well, it has remarkable characteristics of high-precision cutting of components with longer length compared with the diameter.
In general, if long and narrow parts are processed with a general-purpose lathe, flexure will occur on the workpiece, making finishing with the correct dimensions impossible. The Swiss-type automatic lathe utilizes a guide bush to function as a material steady rest. The tool, positioned at a certain distance from the guide bush, gives a cutting motion only the direction of outside diameter. This allows the workpiece to be cut accurately with no flexure. As for axial motion, the headstock, rather than the tailstock, moves while clamping a workpiece.


NOTE 2: Non-guide bush type
This is a sliding head-type automatic lathe which is designed based on the Swiss-type automatic lathe with a guide bush dismounted. Without a guide bush, it is not well suited for machining narrow and long parts. If the workpiece is short and does not deflect, however, such material can be handled effectively.
With the Swiss-type automatic lathe, the rear side of a bar material needs to be handled as waste as a portion equivalent to the size of the guide bush structure which functions as a steady rest for the material cannot be machined. The non-guide bush type reduces the waste to about 1/3 in length compared to the waste made by the guide bush type.


NOTE 3: Star Motion Control System
General machining, when NC controlled, is composed of the following processes:
[Tool selection] → [Approach] → [Cutting] → [Retract] → [Next tool selection] → [Approach] → [Next cutting]
In this process, non-cutting time largely affects the machining time. The Star Motion Control System has a function to reduce this non-cutting time.
The Star Motion Control data can be created easily by NC program conversion through “optimization”. This “optimization” finishes processing related to computing processing in advance in NC-controlled operation to reduce non-cutting time. It also controls spindle speed change and other controls at the right time and converts a series of operation from [Tool selection] through [Approach] to a smooth locus in order to contribute to the reduction of non-cutting time.
Furthermore, the Star Motion Control System exerts an effect on other than the reduction of the cycle time. The NC control system moves each axis at a maximum rapid feed rate in the non-cutting process, while the Star Motion Control System moves each axis at a minimum acceleration/deceleration speed by maximally utilizing a waiting time for other path system. The axis control system without using the rapid feed rate controls excessive vibration and maintains stable machining accuracy. It also reduces power consumption by peak current suppression during axis movement and the load on ball screws and other consumables, contributing to a longer lifespan.


NOTE 4: Spindle sleeve slide guideway structure
This structure has a sliding surface machined according to the outer diameter of the head stock spindle sleeve, which moves while clamping the workpiece. By eliminating the gap between the spindle sleeve and the guideway, the structure supports the cutting load applied to the head stock through the slide guideway and improves the head stock rigidity.


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