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• # Dough rounding machine inner workings

Discussion in 'The main mechanical design forum' started by Rogelio, Dec 21, 2013.

1. ### RogelioNew Member

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Dec 2013
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Hello, I have seen a machine that can round bread dough very easily and dont undestand how the movement is achieved.
As you can see, there are 2 drums that turn at the same time, one outer, one inner. The inner drum's movement is what I cant figure out. In my opinion it turns at the same rate and direction as the outer drum, but not only does that, also there is another movement, a "circular" movement around the longest axis, that moves the dough pieces around the edges of the outer drum.

http://youtu.be/fFjovsZokcc
http://youtu.be/6gicSTS-nCo?t=13m35s
http://youtu.be/2VF_ipbpgAM?t=4m42s
This last video is very interesting because you can see how the drum in still position goes in and out in a circular movement, combine that with the rotation and its like using the hand to make a dough ball.

My question how that circular movement of the inner drum is produced?

2.
3. ### LochnagarWell-Known Member

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The dough mixture "falls" into the large holes in the outer drum - thus the dough balls have a component of velocity that is approximately vertical (and obviously a momentum associated with that) - when it enters these large holes.

In addition to that - the inner drum has a reciprocating action (along the axis of the drum) - in addition to rotary motion. The outer drum and the inner drum appear to be rotating at the same speed - which means they are driven by the same "gear".

So when the dough ball enters the large holes in the outer drum - it has this vertical momentum - and then - with the inner drum reciprocating axially - this causes the dough ball to move within the round hole of the outer drum (it is constrained by the shape of the round hole).

A mechanism for providing the axial reciprocating motion is depicted in the video link below:-
1) The blue drum shown in the video below - is the rotating and axial reciprocating inner drum in the dough machine.
2) So the outer drum of the dough machine (not shown in the video) would be keyed to the orange gear in the video shown below.

However, this particular video shows only one axial reciprocating motion (one cycle) - for each revolution of the gear. In the dough machine - it looks as though there are several reciprocating cycles - for each revolution of the gear. Thus - using this example - the path in the green coloured element would have to "meander" several times - in order to generate - the higher frequency of axial reciprocating motion seen in the dough machine. I hope this video gives you some inspiration of just one way in which this motion can be achieved.

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Last edited: Dec 22, 2013
4. ### RogelioNew Member

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Dec 2013
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Hello Lochnagar, thank you for the explanation. I am not an engineer but now I think I can try to explain to one here in my country what is that I need. Again, thank you.

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