Matakuliah
Tahun
: D0164 / PERANCANGAN ELEMEN MESIN
: 2006
Pertemuan 23
CAM
1
LEARNING OUTCOMES
Pada akhir pertemuan ini, diharapkan
mahasiswa akan dapat menggunakan
metode yang tepat untuk merancang ulir
gerak
2
OUTLINE MATERI
• Definisi Cam
• Cam and Follower
• Tipe Cam
• Cam Eksentrik
3
CAMS AND FOLLOWERS
CAMS and FOLLOWERS
V. Ryan © 2002
Have you ever looked closely at a simple mechanical toy ? If you have the
opportunity to study one closely you will see that it is made up of
mechanisms,
usually
including
CAMS.
Can you name any mechanical devices that use cams as part of its
movement?
A CAM changes the input motion,
which is usually rotary motion (a
rotating motion), to a reciprocating
motion of the follower. They are
found in many machines and toys
4
CAM AND FOLLOWER
A CAM changes the input motion,
which is usually rotary motion (a
rotating motion), to a reciprocating
motion of the follower. They are
found in many machines and toys
A CAM has two parts, the FOLLOWER
and the CAM PROFILE. Diagrams one to
six show a rotating cam pushing a
follower up and then allowing it to slowly
fall back down.
There are different types of follower but they all slide or roll on the
edge of the cam. Various types are shown below.
FLAT
POINT/KNIFE
ROLLER
OFFSET
5
TYPICAL USE OF CAM
Below is a typical use of a cam. A simple toy based on a cartoon
character (Ed the Handyman) is controlled by a cam and
follower. As the cam rotates in an anticlockwise direction, the
follower falls and so does the arm of the toy. As the cam
continues to rotate the arm begins to rise as seen in diagram 4.
The cam shown is a pear shaped cam (named after its shape).
6
ECCENTRIC CAM
PRACTICAL EXAMPLE - ECCENTRIC CAM
V. Ryan © 2006
An eccentric cam is a disc with its
centre of rotation positioned ‘off
centre’. This means as the cam
rotates the flat follower rises and
falls at a constant rate. This type of
cam is the easiest to make and yet
it is one of the most useful.
The diagrams (1 to 7) seen below
show the cam rotating in an
anticlockwise direction. As it
rotates it pushes the flat follower
upwards and then allows it to drop
downwards. The movement is
smooth and at a constant speed.
7
CAM - EXAMPLES
CAM - EXAMPLES AND QUESTIONS POSSIBLE ANSWERS
V. Ryan © 2002-2006
As you have seen in the previous examples, cams can be used to
change rotary motion into linear motion. Examine the cams on this
page and explain how the various cam profiles control the movement
of the followers.
1. What is the name of this cam
profile? Explain how it controls the
movement of the follower.
PEAR SHAPED CAM. As the cam
rotates, the follower stays level for
½ a revolution, then it rises and
falls following the cam profile.
8
CAM - EXERCISE
3. What is the name of this cam
profile? Explain how it controls the
movement
of
the
follower.
ECCENTRIC CAM. The follower
moves up and down in a vertical
direction. Its movement is very
smooth.
4. What is the name of this cam
profile? Explain how it controls the
movement
of
the
follower.
SWASH CAM. This cam is like a
‘spinning top’. As the angled disc
rotates the follower rises and falls,
following the movement of the
disc.
9
CAM - EXERCISE
5. What is the name of this cam
profile? Explain how it controls
the movement of the follower.
BOX CAM. As the disc (cam)
rotates, the follower - follows a
groove cut into the disc.
6. What is the name of this
cam profile? Explain how it
controls the movement of the
follower.
FLAT PLATE CAM. The
follower
rises
and
falls
according the movement of
the cam profile , as it travels
from left to right.
10