Creo Tutorials - Case Study - Slider Crank Linkage Assembly

okay welcome back ladies and gentlemen in this video we're gonna assemble a slider-crank linkage this is going to be our case study just to show you how an actual assemblies put together and then we're gonna do kinematic and dynamic analysis so it's gonna serve as a kind of clothes out you know just a example to show you how assemblies work so you should do this just to kind of reinforce what you learned in the previous videos and then it's gonna be a slight transition into the next set of videos which is going to be concentrated on kinematic dynamic analysis on mechanisms but I'm thinkin ahead too much but let's look at this these are the parts that I've made and I'm gonna compare them side-by-side to this linkage so let's look at this linkage first we have a pin around which we have this link that's rotating that link is connected to this driven link this long one and it's connected through a pin inside of it right there and then we have a slider that's constrained by a sliding path and the rotation of this is attached this driven link is attached to the slider and the rotation of this link is causing this motion of sliding back and forth one of the most common applications for this is a piston in a car engine if you understand how we just work or even if you've just seen an engine you always hear people talking about you know eight cylinder four cylinder six cylinder they're talking about essentially you know the Pistons that's that's one application we could analyze it and just see how it is they're more like you know actually trains I think trains had them I'm not sure actually so these are the parts that I made right here this is a stand which is essentially the main pin right here around which we have our link rotating just terminology right off the bat we have this driving link then we have the driven link that's what I'm gonna call it this is the pin for the driving link the the driving link is gonna rotate around this pin then we have the driving link itself which is a small link right here then we have the driven link which is a lengthy one then I got a pin that's gonna connect both of them then I have a slider this is the brick this is the yellow brick in the animation right here that I made it's essentially a brick with the cylinder on it you should be able to make that in creo and then we have a path for this brake to slide in and that's what this is gonna serve as it's very simple part again just make this shape and extrude it outwards not very complicated at all just make sure you dimension things properly make sure the path so that this distance right here when you make this shape this distance this gap should be the same same as the width of this brick right here so just make sure it makes sense physically and just like that it depend the diameter for this pin is the same as the diameter in these holds for the links things like that they're pretty straightforward we just want to mention them anyway so do you have this sub assembly made in this sub assembly I'm gonna make a slider slider component of this so I guess I should explain we can divide this up into two different sub assemblies we have this yellow brick that's sliding back and forth in this path and then we have these two links that are attached to this brick so we can assemble them separately from one another and bring it together in one main assembly that's what we're gonna do and I I want to do that because I want to reinforce the idea of using sub assemblies and just kind of show you that it's easier to manage sub assemblies than it is to manage just one giant assembly of 1500 different parts it's just easier to make changes that way and it's uh it's just the preferred way for me I guess definitely recommend that you do it the same way so let's bring in our main slider a slighter path right here so if you remember from the second video when you want at least one part in our assemblies that doesn't move in any way so all these degrees of freedom should be taken away and I'm gonna do that by selecting default I'm gonna click default and it's gonna fully constrain it and I'm gonna hit okay now if I do drag components and I try to drag it nothing should happen and as you can see nothing's happening we want that that's that's good practice and that's what we're gonna do now in this I'm gonna constrain a brick and I'm gonna use the slider slider connection for it I'm gonna bring in the brick and you're gonna get to a point once you keep using cRIO often enough where you're gonna know exactly which set of constraints you need to make for any particular connection so when I select slider connection here I already know it's gonna ask me to align the axes and you don't need to go into placement every time you can see it on the bottom left corner right here it's already giving me the prompt to select axes or edges that are gonna align and it's it's gonna tell cRIO that this is the direction in which we want the part to slide so I'm gonna select this this edge right here let me get rid of these datum planes and I'm gonna select this edge once you select that edge I'm gonna select another edge from the main assembly from the path and look at that it immediately places that brick right next to those two straight edges because now we define the path in which we're allowed to go back and forth but we still have another degree of freedom it's we still have this rotational degree of freedom which we don't want because you know physically this makes no sense we can't have bricks you know going into parts like that so we'll constrain it will constrain the surfaces we'll just select these two and and that happened to be it didn't happen to be that exactly is the next constraint it's asking us to constrain the rotation which is what we did and once you keep using these kind of connections you're gonna get to a point where you're gonna know it and you're just gonna do this whole thing in two seconds I'm just going over it just to kind of show you but eventually I'm gonna just do things without explanation and it can't expect you to know what it means because we have used it often enough I'm gonna hit okay so now it's a lot to slide back and forth and the way I'm doing that again is I'm pressing ctrl alt I'm pressing and holding ctrl alt and then I'm left clicking and dragging the component that I want to move and that's how I can do this now I could have gone further and I could have constrained this slider connection by giving it a maximum and minimum distance but I'm not gonna do that because that happens automatically if we look at this linkage again the the movement of this yellow brick is not limited by anything here it's limited by this small link because this the small link can only go a certain distance which is its own length to the right and it can only go a certain distance which again it's its own length to the left so the maximum distance this is gonna be displaced back and forth is two times the length of the small link so we already know this this is how it's gonna be constrained we don't really need to do it ourselves and you know we're gonna leave it like this so I'm gonna save this I'm gonna hit save always save your work Oh didn't regenerate let me just regenerate you can hit the regenerate button or you can press ctrl G on your keyboards or I think I don't know what it is Oh Mac I'm not gonna even try to guess but ctrl G and you should be able to regenerate then save it and then close it you can close it by hitting this file button right here because what that allows you to do is again stay within the Korea environment and you know it allows you to close window for the assembly and now we're gonna make a new assembly I'm sorry I'm trying to open it so we're gonna make a new assembly and I'm gonna call this the main assembly now the reason I'm not making another sub assembly is because once we assemble the linkage we can just bring in our slider sub assembly and just put it together right there so we don't need to make three assembly files we just need to make one sub assembly one main assembly but we're still putting together two separate sub assemblies but we're gonna have one main I guess I kind of confused you there with the wording but you'll see what it means because I like to have my sub assemblies ahead of everything I'm gonna call this main assembly okay open up the datum planes I'm gonna start this if we look at this again we can make this main pin around which this driving link is rotating we can make that our default we can make that our part that doesn't move so I'm gonna do that I'm gonna bring in this I'm calling it a stand it's not really his then I'm gonna say it's default and that's that so this is the pin around which our link our driving link is going to rotate I'm gonna bring in link 1 and we already you should already know that this is gonna be a pin connection right here I'm gonna select the pin connection and again it's asking me for axes around which we wanted to rotate I already know this I'm not gonna go into placement every time and then obviously it's gonna ask me to limit this degree of freedom right here because if you look at the degrees of freedom we have now we were allowed to rotate which which is what we want but then it's also able to slide we don't want that and in a pin connection it's always gonna ask us to limit that linear back-and-forth after the axis alignment I already know this so I'm gonna select this you could go to placement and you know do translation but I'm not gonna keep doing that and that's okay and now I should be able to move this and I can look at this it's it's it's going well but I'm gonna chase the appearance now just to kind of differentiate between the two even though we only have two components it's just good practice to color your components differently and you know okay so let me bring in the smaller pin that's gonna connect the bigger link this is our pin again the pins gonna have a pin connection it's kind of I'm gonna align the axis and now I'm gonna align the two surfaces it's a pin connection actually let me select a pin connection okay so don't make this mistake because you might jump the gun like I just did and without selecting pin connection you just start making in strengths don't do that because that's it's gonna lead to some problems I'm gonna do the same thing again and there we go so we have our pin connection and then we have our pin connection right here so the way to confirm that your parts kind of moving right here is you can kind of just drag it and rotate and see how I'm allowed to kind of move this back and forth it's it's because there's the pin connection if you track or if you just notice the blue little marker right there that's indicating how I'm allowed to move and if I'm allowed to move at all so see right here how it moves with it same things happening right here it's moving with the rotation and that's how I know it's a lot to move so I'm gonna regenerate it now now we can assemble in our larger link but we need to kind of plan this ahead in the way it's gonna come together is if we make this larger link now and then we bring in our sub assembly we can't or we won't be able to constrain this large link to the slider assembly and let me just do that so I'm gonna mess up on purpose right here just to kind of make a point let me assemble this large link and I'm gonna make a pin connection again I'm gonna select a pin and I'm gonna select the axes select the two surfaces that remain in line hit check so you know this is how we want it to work this is this is good this is standee now I'm gonna bring in the sub-assembly that we made I'm gonna say bringing the sliders sub-assembly and then I'm gonna complaisant using the distance constraint now here is where you use that the physical location constraints right here remember from the from the previous videos this is the behavior constraints and these are the physical location constraints and if I'm trying to place a sub assembly I'm only gonna be using these physical location constraints I'm not gonna try to use any of this unless it applies then definitely go ahead and use it but right now I'm just trying to place it a certain distance away a certain distance away from the main link if you look at this right here we have this pin and it's a certain distance away that's all we need to do so I'm gonna do that and I can use datum planes to do this I'm gonna say it's a distance constraint and I'm gonna say this vertical plane for the pin is a certain distance away from this vertical plane of this sub assembly and it already gave me value of how far it is now and I'm gonna say it's let's say 10 just bring it in a little closer and we still have quite a few degrees freedom it's still allowed to rotate like this it's still like to go you know back and forth up and down and we don't want that so we're gonna limit some more things and before I actually do anything let me just make another point whenever you try to constrain sub assemblies that you bring in make sure that you don't constrain moving parts with static components what I mean is if you look at this sub assembly we made it so that we can slide this brick back and forth but if we constrain it to a part or let's say if I use the surface of this line component to constrain and I used the static component and then I hit okay watch it's not gonna allow me to rotate all right it's not gonna allow me to move the slider anymore or it is let me just regenerate this interesting edit definition component coins oh it's still it's still okay let me let me properly constrain this again so use the surface for this this and that now I need to do another one where I do aesthetic vertical I'm sorry let me open up datums let me make the vertical planes coins okay that's fine I think that's fully constrained now it's still I physically fully constrain should be oh that a second at a definition what kind of constraints the way I already have I have a distance constrain then let me get rid of this for now I'll show what that exactly implies well let me just make the horizontal planes coincident and then I'm gonna use that surface constraint that I was talking about before so again I remember this is this slider break that's allowed to move back and forth and I'm gonna use that surface to try to constrain horizontal displacement that's done and now I'm gonna make a new constrain even though I don't really need it and I'm gonna delete it immediately but I guess this kind of highlights how carrillo can be kind of silly sometimes so let's let's do this that's fine that's fine that's fine cheerfully constraint now that three constraints limiting all three directions okay so I'm back and I'm gonna try to show you exactly and kind of make the point how creo can be frustrating sometimes so if you look at this I still have the same exact constraints and right here now I'm fully constrained let's watch again let's go through our constraints I have this distance constrained that I made already between the two planes that's fine then I have this horizontal plane that horizontal plane constrained that I made already and it's fine then I made the constraint between the two moving surfaces and now it's fully constrained if you don't like the video and you if you look at this and I did the same three exact things and it said it's a partially constrained so this is kind of the point I want to make to kind of just get across that you know things like this are gonna happen in creo and don't don't let that you know just fool you sometimes you're doing the right thing and creoles deciding to be silly and that's okay and I'm gonna hit okay now and if it's making any sense they shouldn't be able to move and okay so right here let's examine this again I'm gonna get rid of this points to constrain right here I'm gonna remove this and when I hit okay the brick is allowed to slide back and forth of course it's allowed to move linearly as well but the point I'm trying to make is when you go to at a definition again and make the constrain using a moving surface with a static surface again it's gonna say partial constraint let me make a silly constraint again in rally constraint I'm gonna remove it and look at that it says fully constraint so I had to make a fictitious constrained that didn't make any sense then remove that constraint - for creo to realize that it's fully constrained now so this is that's that's what happens in creo it's okay silly things like that happened but watch it's not allowed to move so let's do it right this time and instead of using the moving surface of this constraint I'm gonna use the static surface of this path because the path is not allowed to move it shouldn't move and I'm gonna try to this isn't properly I'm gonna look at it from the left side so I'm looking at it from the left that isn't clear I'm gonna zoom in right here and we want this shaft right here this shaft end to align with this end right here so we'll say it's a distance constraint instead of instead of a coin stand constraint so let's do maybe negative - okay I think that's fine that's that's enough for me to properly constrain this and I'm gonna say okay now the slider should be allowed to move back and forth because we used a static part and look at that it is allowed to move back and forth and now here's here's what I was attempting to say when I when it said wow that's that's terrible English so if you remember if you roll back in the video roll back I don't know if that's a term but if you rewind back and see that I was trying to say that if you bring in this link before this sub-assembly you're gonna run into problems and this is the problem that you're gonna run into now if I try to modify this link and try to make a pin connection with this slider we're gonna have some problems let's edit definition and look at that the sub-assembly disappears and there's a good reason for that and the reason is obviously because we have this this model tree right here and there's a hierarchy and the thing is it's only gonna allow me to modify this link with respect to the things that I've already made before it not after it so I can only modify things that come in before so I can modify this but it's a sub assembly I don't really want to mess around with these linkages right here I could try to add a definition and do things with it but now see it suppresses the main assembly because I can't modify these connections and try to make connections with the suppressed opera objects so that's why we need to kind of get rid of this large link right here I'm gonna hit the leek and okay and and then I'm gonna bring it in later should not want to bring it in and I hit okay I haven't made any constraints yet I know but now if you look at this tree right here I have the link after the after the sub assembly so if you do this it allows you to actually interact with anything that's before it so just keep in mind and kind of try to plan ahead and see which components might have multiple connections that need to be made and and make sure you have those components assembled last so you can make those multiple connections and constraints so let me edit edit this and let me place some pin connections I may be the same thing as I did before I'm gonna put a pin connection with this right here and then I'm gonna have this surfaces as coincident now I'm gonna make another connection now here's here's another thing I guess here's something new we made one pin connection but we can make multiple pin connections I'm gonna say new set and then I'm gonna select these surfaces again with the pin connection already selected right here I'm gonna say here and then I'm gonna say those two surfaces so I selected the axes alignment again and I selected a translation but I want you to notice that instead of coin student when I selected the two surfaces it automatically applied a distance constraint because if you remember from our left view we left over a little bit of distance above the link or I guess further than the link so it already knows that it's a distance away it's not a coin sitting constraint and we're gonna hit okay and now when I click and drag these components it should essentially behave like this but let's let's look at it moment of truth and it does it's always satisfying to see your assembly work its way wait very fun and it's working now let me just color this red because I think it's white whatever it's fine so now we're gonna do actually I'm gonna stop the video right here and in the next video I'm gonna do the kinematic and dynamic analysis I don't know how long but I'm gonna stop this video right here sorry it got a little confusing with the constraints there when I tried to show you some mistakes that you can make but hopefully it's clear that sometimes you're gonna do exactly the right thing and Krios just not gonna know it and I want you to know it's okay that happens and and just keep trying but let's let's move on to the next video now

Channel: Ashish Rana

Views: 15,527

Keywords: Creo tutorials, Creo Assembly tutorials, Creo, PTC Creo

Id: Um1Ebv1bc-g

Length: 25min 26sec (1526 seconds)

Published: Tue Jul 07 2015