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  • Features and Types of Cam

Features and Types of Cam

What is Cam?

  • A cam is a mechanical part to transfer a purpose motion at a given time in the mechanically designed motion way by contacting directly a different mechanical part. A cam mechanism is to impose rectilinear motion or rotary motion on the driver and thereby to cause reciprocating straight-line motion or reciprocating angular motion of the driven regularly. The motion basically has sliding contact. Although a cam has a simple structure, it can get a complicated motion. As a result, it is widely used to automation machines. A cam is a sort of a unit to change rotary motion to reciprocating motion. A case in point is a cam shaft of automobile which changes the rotary motion of an engine to the reciprocating motion necessary to operate the suction and exhaust valve of a cylinder. A crank can change forward/backward motion or circular motion to reciprocating. A case in point is a crank shaft of automobile which changes the rotary motion necessary for wheel operation and obtains the reciprocating motion of a piston. A cam also makes it possible to check the information saved and the information on tool transfer. Another example is ‘Cam-Drum’ that instructs the movements of various screw tools and chucks, or the notes of music box. The information transmitted and saved by a cam can give answers to the questions ‘what action will occur? and when will it occur? (To make explanation of the subject, music box cam will be more useful. Nevertheless, a cam shaft of automobile can also be used for answering the questions.) A certain cam can be specialized by the displacement diagram that reflects the changes in roller follower made of the rotating cam on a shaft. This diagram is related to an angle position in the location of diameter displacement. Some main terms have something to do with the structure of a plane cam. Displacement diagram displays the not-negative values as graph, typically.
  • Types of Cam

    Plane Cam

  • In a plane cam, the trajectory of the contact points of the driver and the driven has a plane curve. As a sort of non-constraint cam, the cam follower jumps with a rise in speed. A plane cam is dived into such types as circular disk cam, linear cam, tangent cam, face cam, triangular cam, inverse cam, and conjugate cam.
    A circular disk cam sets the point out of the center of a circular disk as its rotation center in order to change the radius distance from the rotation center in rotation. In a linear cam, when a cam has straight-line motion, the follower moves up and down. A tangent cam has some circular arcs and the outline curve to connect circular arcs and a circumscribed circle. It is also known as circular arc and circular disk cam consisting of the tangential lines. A face cam has the grooves of the outline curve of a plane cam. When a face cam rotates, its follower moves up and down. A triangular cam uses vertices of a regular triangle and sets one of the sides as its radius to make a circular arc. As a result, its width is equal regardless of measurement positions.
    In an inverse cam, when link 2 rotes or rocks, the shaft to fix a cam has straight-line motion. A conjugate cam has two cams put in between two rollers. When one cam pushes its follower, the other cam is pushed by the follower.
  • Solid Cam

  • A solid cam is also known as 3-D cam. The trajectory of the contact points of the driver and the driven has a spatial curve. Compared to a plane cam, it can make a spatial volume small and is widely used for automation machines. A sold cam is divided into such types as drum cam, conical cam, spherical cam, end cam, swash plate cam, and globular cam.
    A drum cam is used to get its rotation shaft in parallel with its follower. With the guide grooves over the drum, the shape of a cam is made. It is mainly used to machine tools. A conical cam has guide grooves processed on the surface of a cone. The cam is used as its follower remains at a certain angle and takes reciprocating motion left and right.
    A spherical cam has guide grooves processed on the surface of a sphere. It causes rocking motion left and right in its follower. In an end cam, when a special shape is made on the surface of a drum, its follower moves up and down. A swash plate cam has the same motion as an end cam. Its circular disk is installed slant to rotation shaft for the purpose of reducing cam weight. A globular cam has grooves on a sphere, and the driven has reciprocating turning motion without up-and-down motion.