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Shaper: working principles, classification, Construction, Machining time, MRR
The shaper
Ø In
a shaper , the work piece is held stationary during cutting, while the tool reciprocates horizontally.
a shaper , the work piece is held stationary during cutting, while the tool reciprocates horizontally.
Ø Producing
a flat or plane surface which may be in a horizontal, a vertical or an angular
plane.
a flat or plane surface which may be in a horizontal, a vertical or an angular
plane.
Ø Making
slots, grooves and keyways
slots, grooves and keyways
Ø Producing
contour of concave/convex or a combination of these
contour of concave/convex or a combination of these
Ø Machine
tool used for shaping operation is called shaper
tool used for shaping operation is called shaper
Ø Designed for machining flat surfaces on small
sized jobs. If the size of the job is large, then planning is used.
sized jobs. If the size of the job is large, then planning is used.
Ø The
feed and depth of cut are normally provided by moving the work. Such shaper is
called a horizontal shaper.
feed and depth of cut are normally provided by moving the work. Such shaper is
called a horizontal shaper.
The basic principle of shaping machine is generation
of flat surface by. The cutting motion provided by the linear forward motion of
the reciprocating tool and the intermittent feed motion provided by the slow
transverse motion of the job along with the bed result in producing a flat
surface by gradual removal of excess material layer by layer in the form of
chips. The vertical in feed is given either by descending the tool holder or
raising the bed or both. Straight grooves of various curved sections are also
made in shaping machines by using specific form tools. The single point
straight or form tool is clamped in the vertical slide which is mounted at the
front face of the reciprocating ram whereas the work piece is directly or
indirectly through a vice is mounted on the bed.
of flat surface by. The cutting motion provided by the linear forward motion of
the reciprocating tool and the intermittent feed motion provided by the slow
transverse motion of the job along with the bed result in producing a flat
surface by gradual removal of excess material layer by layer in the form of
chips. The vertical in feed is given either by descending the tool holder or
raising the bed or both. Straight grooves of various curved sections are also
made in shaping machines by using specific form tools. The single point
straight or form tool is clamped in the vertical slide which is mounted at the
front face of the reciprocating ram whereas the work piece is directly or
indirectly through a vice is mounted on the bed.
Construction:
The main parts of the
Shaper machine are
Shaper machine are
- Base
- Body (Pillar, Frame,
Column) - Cross rail
- Ram and tool head (Tool Post,
Tool Slide, Clamper Box Block)
Base:
- 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. - Base absorbs and withstands vibrations and other
forces which are likely to be induced during the shaping operations.
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:
- 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:
head:
- 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.
Working principle:
·
Job is rigidly fixed on the machine
table.
Job is rigidly fixed on the machine
table.
·
Single point cutting tool held properly in the
tool post is mounted on a reciprocating ram.
Single point cutting tool held properly in the
tool post is mounted on a reciprocating ram.
·
Reciprocating motion of the ram is
obtained by a quick return motion mechanism.
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.
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.
During return, there is no cutting action and
this stroke is called the idle stroke.
·
Forward and return strokes constitute one
operating cycle of the shaper.
Forward and return strokes constitute one
operating cycle of the shaper.
Mechanism
In shaper, rotary movement of the drive is converted
into reciprocating movement by the mechanism contained within the column of the
machine. The reciprocating movement of the ram and the quick return mechanism
of the machine are usually obtained by any one of the following methods:
into reciprocating movement by the mechanism contained within the column of the
machine. The reciprocating movement of the ram and the quick return mechanism
of the machine are usually obtained by any one of the following methods:
1. Crank and slotted link mechanism:
2. Whitworth quick return mechanism:
Ram moves at a comparatively slower speed during the
forward cutting stroke. During the return stroke, the mechanism is so designed
to make the tool move at a faster rate to reduce the idle return time. This
mechanism is known as quick return mechanism. As the ram moves at a faster rate during return
stroke, the time taken becomes less. The total machining time decreases and the
rate of production increases.
forward cutting stroke. During the return stroke, the mechanism is so designed
to make the tool move at a faster rate to reduce the idle return time. This
mechanism is known as quick return mechanism. As the ram moves at a faster rate during return
stroke, the time taken becomes less. The total machining time decreases and the
rate of production increases.
3. Hydraulic shaper mechanism
Types of shaper
• Machining horizontal surface
• Machining vertical surface
• Machining angular surface
• Cutting slots, grooves and keyways
• Machining irregular surface
• Machining splines or cutting gears
