New Release of Swiss Type Automatic Lathe SV-20R

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

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

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.