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Assembly mates in SolidWorks: Mechanical mates
January 7, 2012Posted by on
Mechanical mates in SolidWorks….
List below shows the mechanical mates…
As stated earlier in previous post, mechanical mates are used to create mechanisms in an assembly. Prior to assigning mechanical mates, it’s necessary to reduce degrees of freedom of a component such that it can only be moved in the desired direction. Say you want to create a gear mechanism, than first constraint a gear such that it can only be rotated in it’s axial direction.
(You need to do so for the examples given in this post.)
Cam – allows one part(follower) to be in contact while moving the first one(cam)
Chose to create the mate from the property manager and select cam faces one-by-one, which should be tangent in continuity. As a follower selection, you can select a vertex, a cylindrical face, or a planner face. Do so and the follower is attached to the nearest cam face. Now rotating the cam makes follower follow the motion as constrained. In this example, select the cam faces one-by-one, or even you can simply right-click on any one face and use Select tangency option to select each and every face of the cam which is in tangent continuous.
As a follower, you can use any one given. Confirm the mate creation.
Cam mate in SolidWorks
Hinge – acts as a pin joint – only degree of freedom remains is the rotational one
Selection simply follows concentric and coincident selection. Invoke the hinge mate from property manager, and select entities as required. In the example below, as concentric selections, select hole faces one-by-one (in any order), and as coincidence selections, use the side faces.
Hinge mate, without part limits specified
Note that, while defining the mate, you can also define angular limits. Check Specify angle limit, select two references to measure the angle and enter values, 90deg. as current position, 270deg. as max. and 0deg. as min. value(as in limit mate).
Gear – Forces two components to rotate relative to one another
When you rotate one gear, the other one rotates with a specified gear ratio. The mate allows you to define the rotational ratio and direction as well, but does not prevent collision. So if the gear teeth are not correctly designed, it may result in collision while in motion.
Selection is straight forward, select any two components (not necessary be gears, including axes), specify rotation ratio other than the default if necessary. The default ratio will be the diameter of two selected circular edges or cylindrical faces. Specify direction of rotation, default (as if in ‘actual’ gear mechanism) or reverse.
In the example here, select two cylindrical faces as shown, keep the default ratio and direction.
Rack Pinion – moving one component in linear direction causes the other rotate and vice versa
The component translating in a linear direction is known as rack and the other one rotating in an axial direction is known as pinion/gear. Invoke to create the mate from the property manager, select a linear entity as rack and a circular edge or a cylindrical face as pinion/gear.
The mate let’s you specify the movement by two options.
Pinion pitch diameter: define diameter of the pinion (default will be the diameter of selected pinion)
Rack travel/revolution: define distance covered by rack per revolution of the pinion (default will be the product of pinion diameter and pi)
Distance travelled by rack will be the product of the pinion diameter and pi (3.14…) You can also check Reverse to invert translation of rack.
In the case below, select the entities as specified.
Leave the default settings and confirm.
Rack and pinion mate in SolidWorks
Screw – rotating one component translates the other with specified pitch dimensions
Simply select two cylindrical faces or circular edges and define any one option from the following:
Revolutions/mm(or document unit): define how many rotations to perform to move the other component up to a unit length
Distance/revolution: specify how much distance to cover, in document units, per revolution
You can even check Reverse to invert the direction of translation. This works as for right-handed or left-handed threads.
In here, select the cylindrical face of the screw rod and face of the hole in movable jaw.
Note than you can highlight the portion of movable jaw beneath which hole is ‘hidden’ and invoke Select other option, which gives you list of entities beneath the selected one.
Define Distance/revolution to be 15mm, and check Reverse.
an application of screw mate in SolidWorks
Universal Joint – rotates output shaft about its axis based on the rotation of input shaft about its axis
Define two axes or two cylindrical faces belonging to two different shafts, and rotate any of the shaft. This causes the second shaft to rotate.
As shown in the image, select the two cylindrical shaft faces and confirm.
This concludes Mechanical mates. Click here to get the models shown in this post. Keep visiting for more!