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# MCD curved carrier transport with grooves

Creator

I tried to realize a carrier transportation with curved direction.

The carrier is driven by a belt transportation system, but if it has to turn 90°, there is a switch with grooves to lead the carrier to the next belt section (see attached picture). For that the carrier has moveable pins (see attached picture). The ones on the right side drive along the groove of the switch, the ones one the left side are pushed in the carrier body as long as there is any mechanical resistance.

How can I realize this in Mechatronics Concept Designer?

I already defined the carrier as a rigid and collision body, and the belts as transport surfaces.

But it doesn't work with the 90° switch to drive the carrier along the curve. As soon as the carrier collides with the switch, it stops moving.

6 REPLIES

# Re: MCD curved carrier transport with grooves

Siemens Legend

Hello Schisve,

as I see it there are several methods to do curved transport in MCD:

1. Transport Surfaces

You will have to create some dummy geometry (the place where your carrier takes the 90 Degree turn) to realize that in your project. Furthermore you probably have to define your pins as "Collision bodies" and the nut where they are guided aswell. You probably will also have to provide a Collision Material with a low friction. This is not my preffered solution.
MCD Curved Transport with Transport Surface

2. Point on Curve Joints to Guide your Carrier

This is what I do in most of my simulations, you define two or three "Point on Curve joints" and guide the carrier through the path (that way they do not misallign and the simulation performance is better since MCD does not have to calculate all the collisions with the path).

MCD Curved Transport with Point On Curve Joints

I have added the two examples as an attachment.

Best regards

Viktor Braun

# Re: MCD curved carrier transport with grooves

Creator

Hi Viktor,

first of all thank you very much for your creative input and the examples!
In my opinion, Option 2, is quick and dirty to simulate motions.
But therefore, the main idea of the MCD (simulating multibody physics and automation-related behaviour) gets lost, e.g. the process of a turn to lead a carrier in one or another direction.
So I tried Option 1.

I defined all my collision surfaces on the carrier and the turn.
In the beginning the simulation shows a realistic solution:
- The belts drive the carrier as long as the belt and the surface of the carrier on the bottom collide (highlighted)
- The pins on the right side are also in contact with the inner surfaces of the groove
- The pins on the left side are pushed up by the turn components on the left side

But after a turn of maybe 10 degrees, the carrier stops moving forward.
I am at a loss, why does the carrier stuck there?
Seems like there is no drive any more, but the belts (transport surfaces) are still in contact with the carrier and the pins with the groove surfaces.

Maybe, you might take an analyzing look at it.
I attached the assembly and a movie which shows the running collision after the carrier stopped.

Thanks and best regards

# Re: MCD curved carrier transport with grooves

Siemens Legend

Hello schisve,

I had some time to look at your specific assembly. This is only a suggestion and by no means a perfect solution it might or might not fulfill your requirement. But could help you on your way to try different concepts.

(view in My Videos)

Some general notes:

• I have used collisiongroups "5" and "7" that will not collide with each other but with default collision group "0".
• It is much better to use solid collision bodies and not just faces (like in a mesh for example).
• To reduce modeling timeI used a lot of "Meshed" collision bodies where a "Box" would be better suited in terms of accuracy and simulation performance.
This can be optimized but would probably require some modeling.
For example dividing a Collision Body into fragments like one "Box" and one "Mesh".
• You can work with "Collision Materials" to further improve the low friction zones.
• You can "connect" the speed parameters of the single transport surfaces (6 per conveyor) to a single parameter or signal to control all the 6 transport surfaces with one single variable.

Best regards

Viktor

# Re: MCD curved carrier transport with grooves

Creator

Hi Viktor,

thank you so much! It really helped me out!

It make sense to use collision categories and materials!

To understand it totally I have 2 more questions...:

1. How did you choose the values of the collisionmaterials? By trying different values?

2. How did you define the proxy objects (shown in the attached picture)? I tried to get it by editing them, but no objects/curves/etc. are marked... and can you explain the reason to use them? Couldn't find any informations about this type of mechanics.

Best regards and thanks a lot!

Svenja

# Re: MCD curved carrier transport with grooves

Siemens Legend

Hey Svenja,

1. Collision materials:

In MCD the friction between two objects is the product or multiplication between the two colliding collision materials. For example default value for static & dynamc friction is "0.7" so the friction between two default collision materials is 0.7 x 0.7 = 0.35.

In most cases there is also areas with no particular friction for example. A Guide at a side of a material flow in most cases does not need any or just low amount of friction.

2. Proxy Object:

The "Proxy Object" can be defined in the sub assembly or sub part level and then the values inside of the proxy or the geometry can be changed (or overwritten) in the main assembly. For example you could have a Pneumatic Cylinder whose parameters (like maximum stroke or speed) and even the attachment to a base of a fixed joint (where the cylinder is mounted)  can be overwritten by a proxy in a main assembly context.

You can think about it like a placeholder.

# Re: MCD curved carrier transport with grooves

Creator

Hi Viktor,

I still try to reproduce the proxy objects, but it doesn't work.

The problem is, that I can create either a proxy object or a rigid body in the subassembly for the "Zapfen" (like in the attached video). Can you show me, how you defined them?

And there's one more question:

In the example file you used collision category 0, 5 and 7 to build groups.

For creating a new category (like 6), I first have to fill this in the configuration excel file "Customer_Defaults_Collision_Category" of NX11.0/MECHATRONICS. Am I right?

Thanks for your support!

Svenja

(view in My Videos)