Radial Cam: Difference between revisions

Latest revision as of 08:35, 29 August 2016

Description

Radial Cams are one of the most common types of ‘cam’. The ‘radial cam’ is a rotating plate or disc with an outer circumference shaped to produce a required movement (usually linear) to a ‘follower’ which is held against it.

Features and Applications

The radial cam may be a simple recognisable shape, such a circle or ellipse, or may be more a complex profile producing variations in the speed and magnitude of the follower movement, moments of 'dwell’ or a 'sudden drop’ - as with the Snail Cam shown. The sequence of follower movements is designed using a Displacement Diagram and the cam shaped accordingly.

A 'follower’ may simply be a rod, constrained by guides, to slide up and down in a reciprocating motion, as the cam, which it rests upon, rotates underneath it - i.e. as push-rods of some car engines are driven up and down by the engine camshaft. The ends of the 'follower’ may be flat, round, wedge-shaped or pointed for different service conditions or may terminate with a roller for increased wear resistance.

Followers may also be in the form of a lever and when used against these, the cam generates an oscillatory movement.

Animations

Examples from Nguyen Duc Thang's YouTube Channel 2100 Animated Mechanical Mechanisms

Disk Cam Operated Vice - the pink cam has a rectangular slot at its centre so it has linear motion during rotation. This helps move the green clamping head longer and faster.

DT Online Buyers' Guide

Cam profiles (i.e. the shape of the outer edge of the cam against which the Follower engages) can be drawn as a Displacement Diagram using Drawing Instruments or CAD software.

Cams for models can be made simply by drilling an MDF or Ply Disc off-centre to make an Eccentric Cam or by mounting a disc at an angle to a dowel axle to make a Swashplate.

The use of Cams can most easily be explored using Contruction Kits such as those listed below.

Click top left to enlarge


Engino "STEM Mechanics" Cams and Cranks Set	Engino "STEM Mechanics" Levers and Linkages Set	Fischertechnik 536622 - Mechanic & Static 2	Engino Mechanisms Set	Engino Gears Set

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 =====Features and Applications=====
-The radial cam may be a simple recognisable shape, such a circle or ellipse, or may be more a complex profile producing variations in the speed and magnitude of the follower movement, moments of ''''dwell’''' or a ''''sudden drop’''' - as with the ''''snail cam’''' shown. The sequence of follower movements is designed using a '''[[Displacement Diagram]]''' and the cam shaped accordingly.
+The radial cam may be a simple recognisable shape, such a circle or ellipse, or may be more a complex profile producing variations in the speed and magnitude of the follower movement, moments of ''''dwell’''' or a ''''sudden drop’''' - as with the '''[[Snail Cam]]''' shown. The sequence of follower movements is designed using a '''[[Displacement Diagram]]''' and the cam shaped accordingly.
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 {|
 |-
-| [https://youtu.be/xGQjTeLqTq0 '''Disk Cam Operated Vice'''] - the pink cam has a rectangular slot at its center so it has linear motion during rotation. This helps move the green clamping head longer and faster.
+| [https://youtu.be/xGQjTeLqTq0 '''Disk Cam Operated Vice'''] - the pink cam has a rectangular slot at its centre so it has linear motion during rotation. This helps move the green clamping head longer and faster.
 | {{#ev:youtube|xGQjTeLqTq0|200x200|right||frame|loop=1&autoplay=0&playlist=xGQjTeLqTq0}}
 |}