work most man-made mechanisms based on the rotational energy.Sometimes, watching from the operation of any machine (in this case, meaning no car, and the mechanism), it would seem that there is no rotation, however, it is often the first impression is deceptive.The fact that many of the machines use different technical solutions, allowing to convert the original character of the movement in its other appearance.One of the most striking examples - a cam mechanism.With its help it is possible to "get" from the rotational motion or translational rocking.Where exactly we can meet the cam mechanism?
Unobvious facts
Surely, every family has the necessary tools including electric drill Impact: its body has a special switch that allows you to choose the mode of operation - only the rotation of the drill-recurrent or progressive displacement along with the rotation.In the first case questions arise: the electric motor via a shaft and gearbox transfers part of its turnover drill.But what happens when you turn mode punching?Nothing complicated - just come into action cam mechanism that converts part of the torque in horizontal displacement.This solution is used in many tools and household appliances.Also, without such arrangements it would not be possible existence of internal combustion engines in their classic form.
simplicity of design, and low cost - are the main advantages of such mechanical transducers.At the same time there is a disadvantage - if the actuator is excessive pressure (resistance movement), it may damage the elements.For example, to break a drill hammer, drilling enough holes to press too hard to drill the surface, effectively blocking its translational movement.
examples from the practice
cam mechanism is one of the varieties of the kinematic pair, consisting of only two units (rack presence is implied) - pusher and cam.The surface of the latter, in which the slip is made profiled that allows you to transfer impulse movement its associated pusher.The cams may be of different shapes: flat, spherical, cylindrical, complicated spatial configurations and so forth. Thus, a separation of only two groups of generalizing - spatial and planar.
consider how to construct the simplest type of flat cam mechanisms.The output unit can move as translational (slider) and turn (Rocker).Side unit in contact with the cam to reduce wear may be formed as a plane, a hemisphere, or the tip is provided with a roller.
In the case of the slide cam egg-shaped cross-section rotates around its axis.Since the shape different from circle, the tops of the roller tappet is lifted, making translational motion along the guides.Recession peaks - and the movie goes down, returning the unit back.Construction with the rocker guide apparatus lacks, however video completely "rolled" on the cam that causes the shift member in accordance with the rotation axis.
Reliable operation cam mechanisms is possible only at a safe contact of the pusher and the cam.To address this issue using several approaches: the output link perform a spring-loaded;in the body of the rotating parts make the groove in which the fixation roller pusher.Itself recess may allow the roller is rolled, while it is not fixed at one point.
Synthesis of cam mechanism is needed for accurate selection of the required process technology parameters.First, create a structural part of the scheme, which takes into account the number of kinematic pairs, units of degrees of freedom, types of bonds.The next stage - the metric.Depending on the desired parameters are selected dimensions of the basic elements.This takes account of the most rational shape of the cam, the force at the vertices flow material to create the structure.
