Institute of Cybernetics at Tallinn Technical University           SOFTWARE DEPARTMENT RESEARCH

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NUT PACKAGE - D-CHAIN

D-CHAIN is a package for calculating dimension chains. It calculates the measurements of the missing links from the given links in the dimension chain. There are two methods to solve a chain:

Fig.1. DIMENSIONAL CHAIN
Fig.2. SCHEMA OF DIMENSIONAL CHAIN
  1. - A0 is closing link
  2. - A1 - cog wheel
  3. - A2 - ring
  4. - A3 - cog wheel
  5. - A4 - rack

In both cases two different calculating methods are used:

In the case of the direct task the closing link parameters are given and program calculates parameters of other links . When solving the indirect task the program calculates the closing link parameters using parameters of the other links.

Fig.3. FOUR MEASURES OF THE LINK


Every link has four measures which are shown in Fig.3. Higher tolerance, Tolerance, Lower tolerance and Average tolerance. And they are related to each other with these formulas:

Ec = (Ec + Ei) / 2
Es = Ec +  T / 2
Ei = Ec - T / 2


Fig.4. ENTERING CHAIN'S LINK VALUES
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the image to see it enlarged

First, when you start the program, you have to say how many links the chain has. Number of links varies from two to six (closing link not included). If you choose two links then you have to specify whether chain is fit or not. Nominal values of links can be entered into boxes next to the link numbers (Fig.4).

There are three ways to compute the tolerances:

  1. Analyze, finding missing tolerance parameters
  2. Project calculating with worse case method
  3. Project calculating with probability method

Fig.5. PRESUMPTION METHOD
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the image to see it enlarged
Fig.6. FIT'S RESULTS
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the image to see it enlarged

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