Cad Cam Development



Submarine’s propellers and CAD/CAM in military shipbuilding

110326-N-7058E-050 ARCTIC OCEAN (March 26, 2011) CNN correspondent Kaj Larsen films a documentary segment in front of the sail of the attack submarine USS Connecticut (SSN 22) after the submarine surfaced through the ice in the Arctic Ocean during Ice Exercise (ICEX) 2011. (U.S. Navy photo by Lt. Ed Early/Released)

Propeller of submarine

Firstly watch a Ohio class submarine in a dock here

Submarine

Propeller of submarine

A place where two US subs collided

Propellers for submarines are made out of beryllium bronze. It has very interesting physical properties like on of the highest melting point, flexural rigidity, thermal and acoustic conductions. Look at the article in Wikipedia about Beryllium to get more information.  The point in submarine’s propellers is to manufacture them as thin as possible so that the submarine could produce low noise and as strong as possible so that the submarine can achieve speed. The manufacturing of propeller is quite complex and iterative. Firstly, you have to perform bronze continuous/industrial casting. Then quenching then milling and the last stage: most important: to lay a berillium layer on the bronze and perform milling once again. Over couple of iterations you get a propeller for submarine. That’s interesting, requires big knowledge and engineering experience, isn’t it? If you don’t have advanced milling technology you won’t produce them. You can read here that Back in the mid-1980s, the Japanese company Toshiba sold propeller milling machinery to the Soviets through the Norwegian Kongsberg firm; this and other submarine intelligence furnished by the Walker spy ring resulted in significantly quieter Soviet subs by the later part of the decade. As writer Neal Stevens wrote about the Akula-class Soviet boats, “The combined results generated a steep drop in broadband acoustic noise profiles.” . 

Submarine and noise level. US vs Russians

 

Error compensation in milling is crucial in obtaining accurate part - for instance propeller

 The point is not only in materials, but also in milling. There many technologies of tool’s error compansation in 5C milling machines. This the the hot topic for the researchers and is quite complicated. Check CAGD to see some latest achievements in it. Generally you can classify them as geometrical compensation, force compensation and FEM compensation, thermal compensation. The accuracy of parts produced in milling has been studied for over 80 years right now. It’s crucial in high-precision industry.  Errors in the final dimensions of the machined part are determined by the accuracy with which the commanded tool trajectory is followed, combined with any deflections of the tool, part/fixture, or machine caused by the cutting forces. As part accuracy demands have increased, these error sources have received significant attention from researchers and machine tool builders alike. Due to these efforts, manufacturers now implement sophisticated error compensation algorithms to reduce the effect of geometric errors in the machine structure. Improved designs combined with software error compensation have reduced the effect of thermal error, although this can still be a major contributor. High performance axis drives coupled with modern control algorithms have improved trajectory following dramatically. Pre- or in-process compensation for milling force errors is less common. [Case study: A comparison of error sources in high-speed milling,Tony L. Schmitz, John C. Ziegert, J. Suzanne Canning, Raul Zapata, ScienceDirect, Elsevier]. Read this publication to get introductory insight into milling compensation methods.

Do you remember the disaster of Russian submarine Kursk?  There many submarines going everywhere nowadays and there are many accidents with them. This is unbelievable how active they are how often some accidents happen. Read the following articles and see the dates to get preview on activity of submarines and importance:

  1. BRITISH and French nuclear submarines which collided deep under the Atlantic
  2. British and French nuclear submarines crash in Atlantic
  3. Chineese submarine collides with sonar array towed by U.S. Navy ship
  4. US navy vessels collide in Gulf

Submarine Kursk-class

If you are a fan of military famous stories check the following links:

Major 21st submarine accidents

Some finally thoughts. There are many accidents with submarine’s crush. There are crushes between two modern submarines (even from the same country), and on the other hand, we have got quite powerful sonars and radars ( US can spot a submarine from Murmansk, Russia ). That’s a good question – why do the submarines collided?  The advancement of technology is unbelievable. There are two cores of this: the knowledge about materials and the production technologies we have today (CAM). CAD/CAM is indispensable in developing new products. Better materials and better machining technologies and chemical technology are crucial not only in producing propellers for modern submarines, but also in aviation, automotive etc.

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Comments

  1. * bob Wallace says:

    I would like to purchase the gold colored submarine propeller in your above images. how much is it in us dollars? thank you, Bob Wallace

    | Reply Posted 2 years, 8 months ago
    • * Grzegorz says:

      Hi Bob! It is impossible for a private person to buy a submarine propeller. First of all: you do not have access to required chemical elements and materials. You also do not have accurate enough milling machine. There is another problem, that the shapes of propellers are confidential and you cannot get a CAD model of real world propeller. Secondly, in order to buy all those stuffs to produce a submarine propeller you need have substantial amount of money.

      If you want to have it like a key chain or a toy for your children, then it would be still difficult, because milling centers are not interested in producing one very small detail. You had better find an artist who can made a wooden sculpture for you.

      Best Regards,
      Grzegorz

      | Reply Posted 2 years, 7 months ago
      • * george says:

        why still submarines are using propeller?

        Posted 1 year, 10 months ago
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