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Two spindle 1NC

2 Spindle 1NC Lathe

SHIMADA originally developed 2 Spindle 1NC Lathe ’2SI series’ with the concept of ‘Reducing idle time to utmost’ in 1994, and shipped out nearly 1,000 machines till now to the various industries both inside and outside Japan.

About 2 Spindle 1NC Lathe

Generally NC Lathe is called as Single Spindle(Lathe) and has 1 spindle and 1 turret. On the other hand, 2 Spindle 1NC Lathe has 2 spindles and 1 turret. One spindle is used for the machining and another spindle works for the loading/un-loading. When these both operations are completed, the spindle drum indexes 180˚ like a palette changer of machining center, and then the spindle for machining-use is shifted towards the loading/un-loading side, and the spindle for loading/un-loading-use is shifted towards the machining side(ref. diagram1).

Diagram.1

Diagram.1

With the technique written above, you can see SHIMADA’s NC Lathe is fundamentally different from the other company’s 2 spindle 2NC lathe. Although both our and other company’s machines have 2 spindles, the number of the turret(1 turret or 2 turrets) can differentiate the aim of the work.

At the case of many of other company’s 2 spindle 2NC lathe, both 2 spindles provide the machining, and when the machining is completed, as next steps they start un-loading of the work, air-blow to the chuck and the loading of next work materials. These steps are exactly the same as the steps by the single-spindle NC lathe, and which means that essentially there is no difference from the works by 2 single-spindle NC lathe machines. This type of machine can save more space and energy than connecting 2 machines together. However as a structural point of view, it can not conquer the following 2 points of wastes.

I.Time waste for loading/un-loading of work

When using NC lathe, normally the machining time of the work is not widely changed whether to use turret or gang tool(chaser type) if the certain model(machine) is chosen. Rather than that the machining time can be affected more by tooling. Therefore it is necessary to decrease non-machining time to shorten the tact time. However un-loading of machined-work, air-blow to the chuck at necessity then loading of work material, these whole movement takes approx.10 seconds for 6-inch class work, and much longer time will be necessary 10-inch class big work, long material work, complicated shape work and the work with necessity of severe chucking.

[Resolution by 2SI]

At the case of general NC lathe, the time for whole operations(loading, un-loading, air-blow, etc.) is added to the machining time, but at the case of 2SI, it is possible to shorten the tact time as each spindle shares the machining and loading/un-loading, and provides the simultaneous process.

For example, if it takes 15 seconds for the machining and 10 seconds for the loading/un-loading to work on 6-inch class small work, normally the total of these time, which is 25 seconds, will be the tact time. However, at the case of 2SI, 15 seconds of machining time plus few seconds of spindle drum index time can be the tact time, which is approx.17 seconds. (Ref. diagram.2)

In addition, 10-inch class big work and 1 meter long shaft work need much longer time for loading/un-loading at both case of using gantry loader and robot or using as a manual loading machine, so wide time cut will be possible.

Diagram.2

Idle Time Comparison

II.Waste occurred by unbalance time of each O.P.

For example, if it takes 30 seconds on front-side machining with spindle[1] and 45 seconds on back-side machining with spindle[2], spindle[1] can not go to the next step until spindle[2] finishes its machining. In this case, 15 seconds of waiting time ‘ Idle time ’ occurs.

[Resolution by 2SI]

2SI does not give 15 seconds of waiting time, which is occurred at Single-spindle NC lathe and 2-Spindle 2NC lathe.

Suitable works for 2SI series

Structure of 2SI series

(1) Orientation and accuracy of each spindle
  • The spindle’s magazine-drum is positioned by a large diameter, precision curvic coupling.
  • The index difference between SP1 & SP2 is adjusted by parameter OFF-SET function. (Guaranteed ±1μm repeatability).
(2) Scraping on all ways
SHIMADA provides hand scraped for all products including 2SI series.

Various conjugated method of 2nd spindle

With using the merit of having 2 spindles and 2 chucks and also the spindle of work’s loading/un-loading side is always outside the machine, it is possible to take in the following tasks onto the loading spindle without extending the time.

(1) Air-blow to chucks, workpiece, gantory-loader
SHIMADA’s 2SI does not extend the tact time also when the robot or loader provides loading/un-loading of work or diligent air blow if they are done in the machining time.
(2) Measuring(gauging) diameter, length of workpiece
Sample movie
(3) Work’s deburring