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Double Revolving field theory-how the rotor develops torque
Bme
1. Introduction:
The shaper is a machine tool used primarily for:
1. Producing a flat or plane surface which may be in a
horizontal, a vertical or an angular plane.
2. Making slots, grooves and keyways
3. Producing contour of concave/convex or a combination
of these
2. Working Principle:
The job is rigidly fixed on the machine table. The single
point cutting tool held properly in the tool post is
mounted on a reciprocating ram. The reciprocating
motion of the ram is obtained by a quick return motion
mechanism. As the ram reciprocates, the tool cuts the
material during its forward stroke. During return, there is
no cutting action and this stroke is called the idle stroke.
The forward and return strokes constitute one operating
cycle of the shaper.
4. Construction: The main parts of the Shaper machine is
Base, Body (Pillar, Frame, Column), Cross rail, Ram and
tool head (Tool Post, Tool Slide, Clamper Box Block).
Base: The base is a heavy cast iron casting which is fixed to
the shop floor. It supports the body frame and the entire load
of the machine. The base absorbs and withstands vibrations
and other forces which are likely to be induced during the
shaping operations.
5. Body (Pillar, Frame, Column): It is mounted on the base and
houses the drive mechanism compressing the main drives, the
gear box and the quick return mechanism for the ram
movement. The top of the body provides guide ways for the
ram and its front provides the guide ways for the cross rail.
Cross rail: The cross rail is mounted on the front of the body
frame and can be moved up and down. The vertical movement
of the cross rail permits jobs of different heights to be
accommodated below the tool. Sliding along the cross rail is a
saddle which carries the work table.
Ram and tool head: The ram is driven back and forth in its
slides by the slotted link mechanism. The back and forth
movement of ram is called stroke and it can be adjusted
according to the length of the work-piece to be-machined.
8. Types of shapers
Shapers are classified according to various aspects.
1) Based on type of mechanism employed for the movement of
the cutting tool i.e. tool carrying ram the shapers are
classified in to three types
a. Crank type
b. Gear type
c. Hydraulic type
9. 2) According to position and movement of ram the shapers
are classified in to three types
a. Horizontal type
b. Vertical type
c. Travelling head type
3) Shapers are classified in to two types based on design of
the work table
a. Standard shaper
b. Universal shaper
4) Based on type of cutting stroke employed these are
classified in to
a. Push type
b. Draw type
10. Crank type shaper
In these shapers the reciprocating ram is driven by crank
mechanism. In this a single point cutting tool is employed to do
the operation. A crank is connected to the ram and the bull gear
to which the power is given through an individual motor. These
are most common type of shapers being used. The reciprocating
length of tool will be always is equal to the length of stroke.
Gear type shaper
These are the rarely used shapers. In these shapers a rack and
pinion are employed the rack is attached to the lower part of the
ram and on which the pinion moves. The power is transmitted
from the bull gear. A grain train is engaged for the transfer of
power from the bull gear to pinion.
11. Hydraulic type shaper
These shapers run on hydraulic power. The end of the ram is
connected to a piston fitted in to a cylinder. Oil is fed in to
the cylinder initially the oil acts in one direction and the ram
moves in one direction. A varying pressure is applied on the
oil so as to obtain the reciprocating motion of the ram. One
of the main advantage of this shaper is a constant speed can
be obtained from the starting of the machining operation.
There will be no fluctuations in the cutting speed and stroke
of the ram. Another important advantage of this shaper is no
sound will be produced hence a noise free environment can
be obtained.
Horizontal shaper
As the name indicates these shapers have the motion of ram
along the horizontal axis. This type of shapers is generally
used for generation of fine and flat surfaces.
12. A quick return mechanism is used where there is a
need to convert rotary motion into reciprocating
motion. As the disc rotates the black slide moves
forwards and backwards. Many machines have this
type of mechanism and in the school workshop the
best example is the shaping machine.