Advanced Technologies. Globoidal cam mechanisms are widely used in industry. Compared to other cam-follower systems, the globoidal cam-follower mechanisms have many advantages, such as: compact structure, high loading capacity, low noise, low vibration, and high reliability. They are widely used in machine tools, automatic assembly lines, paper processing machines, packing machines, and many automated manufacturing devices.
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This tutorial adds the 5 elements you need in the model before we do Add 3D-Cam. Commercial Indexing Cams: 'Indexers'. Commercial Cam Indexers are nearly always enclosed in sealed, oil-filled cam-boxes. The cam-box is often cast, and then CNC machined to accurately locate the input and output shafts. Even so, there is often an eccentric to finally adjust the position of the output-shaft relative to the input-shaft.
The input and output shafts extend outside of the cam-box. Backlash free, torsionally stiff couplings are used to connect the shafts to the other parts of the machine. Often, the input-shaft is connected directly to a geared-motor. This is not as easy as it sounds, because the load inertia and torque varies considerably within each index period.
For example, use a gearbox to drive the input-shaft so that motor rotates at near to its maximum rated speed at the maximum intended indexing speed. With the gearing, the motor behaves as a flywheel. If the input-shaft cannot rotate at constant velocity, the motion of the output-shaft will not follow exactly the indexing motion. This can cause damage to the Cam-Box, or damage to your machine. If the motor input speed is faster than planned, the accelerations and speeds of the output-shaft may far exceed that of the original motion-design.
When the speed of the input-shaft is faster than intended, it is called 'over-run'. This is needed when there are many 'Stops'. Read the catalogues carefully. Distance [ mm ] between the Input and Output Shaft. The Input-Shaft makes 4 complete rotations for each single rotation of the Output-Shaft. The Number-of-Degrees the input-shaft rotates to index the output-shaft. A Plane for the sketch of the Cam-Blank. A Plane for the indexing Part, which is the Cam-Follower.
A Plane for the sketch of the Cam-Follower Roller. The Motion for the Cam-Follower Part. Design Note: When there are only a few 'Stops', such as four, the Pressure Angle can be high and the Cam Rib width between the rollers can be small.
The 'Select Motion' drop-down box shows all of the motions in Motion Designer. In one cycle of the MMA :. This is how the model looks. The Cam-Follower Rollers. They are at equal angles around the Cam-Follower Part as a 'dial', or 'turret'. We will add two 3D-Cams.
Hence, we need at least two Cam-Followers. However, you can, if you want, add all eight of the Cam-Follower Rollers to see the cam engage with a roller for each rotation of the cam. However, this is not necessary. Remember, most of the effort below is not necessary. You only need to add two cam-followers to get two cam tracks in the cam.
Thus, you only need to add two Lines, Planes, Mechanisms and Rollers. Prepare a layout sketch for the eight Planes and Mechanisms — see image — the layout sketch is in the Cam-Follower Part. If we use constraints, we can reduce the number of dimensions to three. The start-Point of the short Line should be at the end of the long Line. This is important because we will select the short Line to add a Plane and Mechanism-Editor.
Then we can sketch the Cam-Follower Roller at the Origin. You cannot see the Plane in the Front View. Use the arrow keys to spin the view if you want to see the Plane. The Origin of each Plane is at the origin of each 'short' Line.
This is because the 'short' Lines 'start' at the end of the 'long' Lines. This image shows the eight planes in the Assembly-Tree. My default Extrusion Depth is 30mm.
There are two requirements for the orientation and placement of the Input-Shaft:. See below for more details. The cam-shaft Part is Parallel, or co-planar, with the image above. The Pin-Joint for the cam-shaft, is at image above. Add the Plane and Mechanism-Editor for the cam-shaft.
Add a short Line. Add the cam-shaft to the new Mechanism. The Input-cam-shaft is a Crank. This means it will rotate 4 times in one Machine-Cycle. Click the video icon to the left to view the model so far.
Make a Cam-Blank Sketch. It must have the same 'cross-section' as the block of metal [Blank] before the Cams are cut. Q: Why not use the same Plane as the cam-shaft Plane? A: That is a good question! However, we must put the Cam-Blank a new mechanism. Orientation of the Cam-Blank. To help orientate yourself relative to the other parts and mechanisms, you can use two useful tools. This is the view slightly rotated.
Sketch the Blank and Add a Profile. Add the sketch as a Sketch-Loop. The cross-section of a Globoidal Cam-Blank looks a bit like the sketch to the left! Rename the Vertical Line to 'Axis-of-Rotation'. This will help you judge the sketch-loop for the Cam-Blank. You will notice the cross-section is 'dished'. This gives sufficient space for the swing of the Cam-Follower Rollers.
Edit the cross-section where the Cam-Followers 'enter' the Cam-Blank. The image to the left shows the new Profile with the default 'pink' colour. I have renamed the Extrusion to 'Profile-Cam-Blank'. All the elements are in the correct orientation. You must select the Mechanism-Editor that has the Part that represents the rotating Cam-shaft. Your graphic-area should look like the image to the left.
The Command-Manager dialog-box needs you to select five elements:. In the image, the red arrow at identifies the Cam-Follower. Note that you select the Profile contour and not the sketch. Mech Designer adds the 3D-Cam to the cam-shaft Mechanism. The cam-shaft rotates four times and the Cam-Follower indexes four times.
Q: Why did we increase the speed of the input and output shafts by four times? To be sure, we moved the cam-follower four times, and the also the cam-shaft four times.
A: Use the 3D-Cam dialog-box The 3D-Cam dialog-box opens, as shown to the left. If the 3D-Cam dialog-box does not open when you double-click the 3D-Cam in the graphic-area , use the Selection-Window :. The 3D-Cam dialog-box will open. Flank-Length separator. These angles are relative to the Master Machine Angle. It is sometime helpful to add an 'Extrusion' that is a simplified shape of the Cam Blank. When you add a simple extrusion, it is easier to see where the 'Cam' enters and exits the 'Cam-Blank'.
Now, we must add a 3D-Cam for the other track. However, this time, select the Cam-Follower Roller, as indicated in the image to the left. Here, you can see the two 3D-Cams. The Flank-Length is reduced - see Flank-Length separator, above. The 3D-Cam should be in the correct physical location.
Globoidal cam indexers
This tutorial adds the 5 elements you need in the model before we do Add 3D-Cam. Commercial Indexing Cams: 'Indexers'. Commercial Cam Indexers are nearly always enclosed in sealed, oil-filled cam-boxes. The cam-box is often cast, and then CNC machined to accurately locate the input and output shafts.
Intermittent 4 mov. Description Globoidal cam mechanism with four synchronized intermittent movements. Bilateral outputs. They are constructed in a small enclosure made from iron alloy and are integrated with wide mounting positions. The profile of the cam is designed to provide the best intermittent or oscillating dynamic performance generated by cams rotating at a constant A rotary table of high precision that uses the perfect match of a globoidal cam with constant pitch managed by a brushless or torque motor for total This is achieved through the action of a globoid cam and a set of roller engaged in the cam.
A Case Study of Modelling Concave Globoidal Cam
You may know that Google is tracking you, but most people don't realize the extent of it. Luckily, there are simple steps you can take to dramatically reduce Google's tracking. In Globoidal cam mechanism, index motion is. As operating speed is. Present paper focuses the different motion. After studying the two different cases. The results were discussed after.