Swiss Type Automatic Lathe SV-38R Released

Re-Designed SV Series of Complex Machines Combining Gang-Type & Turret-Type Tool Posts

Star Micronics has developed SV-38R, a new model equipped with the enhanced functions of the SV series of the Swiss type automatic lathe ^{(NOTE 1)}. This model is specifically designed for the machining of complicated-shaped parts to be used in the medical, automobile and aviation related areas. It will be released in April, 2014 in the global market.

The SV-38R ensures a maximum machining diameter of 38mm, and includes two types, adding to the product lineup. Type A has a total of 11 controlled axes (9 linearly controlled axes and 2 rotationally controlled axes) while Type B has a total of 12 controlled axes with the tool rotation axis (B axis) mounted on the turret-type tool post.
Both Types A and B are equipped with the function to select either a guide bush type or non-guide bush type ^{(NOTE 2)} according to the total length of parts to machine.

For front working, a 2-axis controlled gang-type tool post and a 3-axis controlled turret-type tool post are arranged with the guide bush in the center. Each tool post is controlled independently so that turning, drilling and milling can be done at the same time. By simultaneously working on both the front and rear sides via an 8-axis unit with a Y-axis control function especially designed for rear working, the machining time is reduced.

In addition, the unique Star Motion Control System ^{(NOTE 3)} minimizes non-cutting time needed for switching the control system and changing tools. A variety of check functions, such as an alarm help function for monitoring alarm details on the NC screen, a program check function for checking the contents of a created program in advance, etc. are also available to improved operability and workability.

Features of SV-38R

High Functionality

• The 10-position turret type tool post can accommodate a 2-axis power tool unit for B-axis control at a maximum of five positions (Type B only).
• Either a guide bush type or non-guide bush type can be selected according to the total length of parts to machine.
• The 8-axis unit with a Y-axis control function can accommodate a maximum of 6 power tool units.

High Productivity

• The Star Motion Control System shortens the non-cutting time.
• The 8-axis back working unit with a Y-axis control function realizes efficient machining on the main and back sides at the same time.
• The main/sub spindle motors and gang-type tool post power tool motors have improved output power (compared to Star SV-32).

High Rigidity and High Accuracy

• The non-guide bush type incorporates a spindle sleeve slide guideway structure ^{(NOTE 4)} for high spindle rigidity.
• Both the main and sub spindles each use a built-in motor, and a built-in sensor improves 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] → [Disengagement] → [Next tool selection] → [Approach] → [Next cutting]

In this process, functions other than actual cutting largely affect the machining time.
The Star Motion Control System is 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 the switching of control systems and completes the processes of [Tool selection] and [Approach] during the process of [Cutting], and the [Disengagement] process of the tool and the next [Cutting] process are controlled to start at the same time. By this control method, the time required for the processes of [Disengagement], [Next tool selection] and [Approach] can be minimized to reduce the non-cutting time.
Furthermore, the Star Motion Control System exerts an effect on machining accuracy as well. The NC control system moves each axis at a maximum rapid feed rate to the [Next cutting] process, while the Star Motion Control System moves each axis while taking the shortest way, utilizing the previous [Cutting] process time. This Control System minimizes excessive vibration caused by axis movement at a rapid feed rate and contributes to the maintenance of stable machining accuracy.

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.