Deep Drawing (Previous)-GROUP: Manufacturing Method
Deep Drawing is a process where the sheet metal gets
the most basic shape for embossed materials.With deep drawing it is possible to
get bathtubs, cylinder shaped containers, splash guards etc.To do that the
sheet metal is cut to required dimensions with earlier process is taken and
placed on a die then with a hammer (mostly press) it gets the required force.
The die element that helps the process is called the pressure ring.
There are 3 types of forces are applied during the process
There are 3 types of forces are applied during the process
·
Forming force required for deep drawing.
·
Friction forces
·
Ironing forces on the sheet metal
(Manufacturing Methods Lecture Notes, A.Aran &
M.Demirkol, p 8-16)
Deep Drawing (New)
Deep Drawing operation is the process of forming a
flat piece of material (blank) into a hollow shape by means of a punch which
causes the blank to (low into the die-cavity, Figure 4.30.
The depth of draw may be shallow, moderate or deep.
If the depth of the formed cup is up to half its diameter, the process is
called "Shallow drawing". If the depth of the formed cup exceeds the
diameter, it is termed as "Deep Drawing". Parts of various geometries
and sizes are made by drawing operation, two extreme example being bottle caps
and automobile panels.
(C. Elanchezhian,B. Vijaya
Ramnath, Manufacturing Technology-1, page 214.)
New
definition is better than previous, new one is more understandable.
New definition is
better than previous, new one is more understandable.
Water Jet Machining (Previous)-METHOD:
Manufacturing method
When we put our hand across a jet of water or air, we feel a considerable concentrated force acting on it. This force results from the momentum chance of the stream and, in fact, is the principle on which the operation of water or gas turbines is based. In water-jet machining (WJM) (also called hydrodynamic machining), this force is utilized in cutting and deburring operations.
The water jet acts like a saw and cuts a narrow groove in the material. A pressure level of about 400 MPa is generally used for efficinet operation, although pressures as high as 1400 MPa can be generated. Jet-nozzle diameters range between 0,05 and 1 mm. A variety of materials can be cut, including plastics, fabrics, rubber, wood products, paper, leather, insulating materials, thickness can range up to 25 mm and higher. Vinly and foam coverings for automobile dashboards (as well as some body panels) are being cut bu multiple-axis, robot-guided water-jet machining equipment. Because, it is an efficient and clean operation compared with other cutting processes, it is also used in the food-processing industry for cutting and slicing food products
The advantages of this process are as follows:
-Cuts can be started at any location without the need for predrilled holes
-No heat is produced
-No deflection of the rest of the workpiece takes places; thus, the process is suitable or flexible materials.
-Little wetting of the workpiece takes places
-The burr produced is minimal
-It is an environmentally safe manufacturing process.
When we put our hand across a jet of water or air, we feel a considerable concentrated force acting on it. This force results from the momentum chance of the stream and, in fact, is the principle on which the operation of water or gas turbines is based. In water-jet machining (WJM) (also called hydrodynamic machining), this force is utilized in cutting and deburring operations.
The water jet acts like a saw and cuts a narrow groove in the material. A pressure level of about 400 MPa is generally used for efficinet operation, although pressures as high as 1400 MPa can be generated. Jet-nozzle diameters range between 0,05 and 1 mm. A variety of materials can be cut, including plastics, fabrics, rubber, wood products, paper, leather, insulating materials, thickness can range up to 25 mm and higher. Vinly and foam coverings for automobile dashboards (as well as some body panels) are being cut bu multiple-axis, robot-guided water-jet machining equipment. Because, it is an efficient and clean operation compared with other cutting processes, it is also used in the food-processing industry for cutting and slicing food products
The advantages of this process are as follows:
-Cuts can be started at any location without the need for predrilled holes
-No heat is produced
-No deflection of the rest of the workpiece takes places; thus, the process is suitable or flexible materials.
-Little wetting of the workpiece takes places
-The burr produced is minimal
-It is an environmentally safe manufacturing process.
(Kalpakjian S. Schmid S.R.,Manufacturing Engineering
and Technology Sixth Edition in SI Units, p. 778)
Water Jet
Machining (New)
The
material is removed due to erosion effects of a high-velocity, small-diameter
jet of water. The process is used mainly for drilling and slitting of sheets
and slabs. Intricate shapes can be easily cut with a very narrow kerf width.
The schematic diagram of water-jet
machining equipment is shown in Figure
10.13. The
equipment consists of the following:
• Water supply system: It consists
of a pumping unit, hydraulic amplifier with outlet pressure of 350-400 MPa, on-off valve and delivery piping.
• Nozzle: The nozzle contains a
saphine insert to form a small-diameter
jet of 0.07 to 0.5 mm. The positioning unit moves the nozzle or
workpiece to bring about the cutting
action. The distance between nozzle and workpiece is in the range of 3
to 25
mm. The positioning unit can be operated manually or with numerically
controlled worktable motion. The nozzles can also
be moved with an industrial robot.
Water-jet machining is used for cutting soft
non-metallic materials such as paper, wood, leather and foam. The
machining rates
are high. There is no thermal damage to the workpiece.
The
water-jet machine can be used as abrasive water-jet machine for machining hard
materials. Abrasive particles are introduced into the stream after the nozzle.
The common abrasive materials are garnet, silicon and silicon carbide grains.
(Singal
R.K. Et.Al,R. K. Singal, Mridual Singal, Fundamentals of Machining and Machine
Tools, page 158)
Open Die Forging (Previous)-GROUP:
Manufacturing Method
Open die forging is the easiest forging process. Parts are simple shaped and mostly forged between two planar dies. This method generally used for rough shaping and forging before the close die forging.Also this method is more economical than closed die forging, and some big parts can only forged by open die forging.
(Manufacturing Methods Lecture Notes, A.Aran & M.Demirkol, p 4-2)
Open-die forging (New)
This type of forging is
distinguished by the fact that the metal is never completely confined as it is shaped by various dies.
Most open-die forgings are
produced on flat-V, or swaging dies (Fig. 3.17). Round swaging dies and V dies
are used in pairs or with a flat die. The top die is attached to the ram of the press, and the bottom die is
attached to the hammer anvil or, in the case of press open-die forging, to the
press bed. As the workpiece is hammered or pressed, it is repeatedly
manipulated between the dies until hot working forces the metal to the final
dimensions.
Open-die forging, in its
simplest form generally involves placing a solid cylindrical workpiece between
two flat dies (platens) and reducing its height by compressing it. This process is known as
upsetting. Under ideal conditions, a solid cylinder deforms as shown in Fig.
3.18 (a); this is known as homogeneous
deformation. Fig. 3.18 (b) shows deformation in upsetting with friction as the
die-workpiece interfaces; the specimen develops a
barrel shape.
(R. K. Rajput, A
textbook of manufacturing technology: (manufacturing processes),
pages 156-157)
Flat Rolling (Previous)-GROUP: Manufacturing method
The
process of reducing the thickness of a slap to produce a thinner and longer but
only slightly wider product is commonly referred to as flat rolling. It is the
most important primary deformation process. It allows a high degree of closed
loop automation and very high speeds, and is thus capable of providing
high-quality, close tolerance starting material for various secondary
sheet-metalworking processes at a low cost.
Introduction
to Manufacturing Processes, John A. Schey ,p 266)
Flat Rolling (New)
Rolling
is a deformation process in which the thickness of the work is reduced by
compressive forces exerted by two opposing rolls. The rolls rotate as
illustrated in Figure 19.1 to pull and simultaneously squeeze the work between
them.
The basic process shown in our figure is flat rolling, used to reduce the
thickness of a rectangular cross section. Flat rolling involves the rolling of slabs, strips, sheets, and
plates - work parts of rectangular cross section in which the width is greater
than the thickness. In flat rolling, the work is squeezed between two rolls so
that its thickness is reduced by an amount called the draft;
d =
t0-tf
where
d - draft, mm (in): t0 starting thickness, mm (in): and tf
final thickness mm (in), shown in figure 19.3.
(Mikell
P. Groover, Fundamentals of Modern Manufacturing: Materials, Processes, and
Systems, pages 396-397-399)
New
definition is more understandable than previous one. It is better.
(Ibrahim Zeid, Cad/Cam Theory & Practice, pages 200-201)
New definition is better than previous one.
Bezier curve (Previous)-GROUP: Computer Aided
Design
B ezier developed a reformulation of Ferguson curves in terms of Bernstein polynomials for the UNISURF System at Renault in France in 1970.
Degree elevation: The degree elevation algorithm permits us to increase the degree and control points of a B ezier curve from n to n+1 without changing the shape of the curve.
Variation diminishing property
A polygon can be created by the segments connecting the ordered vertices of a B ezier
curve.
In 2D: The number of intersections of a straight line with a planar B ezier curve is
no greater than the number of intersections of the line with the control polygon. A line
intersecting the convex hull of a planar B ezier curve may intersect the curve, be tangent to
the curve, or not intersect the curve at all. It may not, however, intersect the curve more
times than it intersects the control polygon.
In 3D: The same relation holds true for a plane.
Results : (a rough interpretation)
A B ezier curve oscillates less than its polygon.
The polygon's segments exaggerate the oscillation of the curve.
This property is important in intersection algorithms and in detecting the \fairness" of
B ezier curves.
B ezier developed a reformulation of Ferguson curves in terms of Bernstein polynomials for the UNISURF System at Renault in France in 1970.
Degree elevation: The degree elevation algorithm permits us to increase the degree and control points of a B ezier curve from n to n+1 without changing the shape of the curve.
Variation diminishing property
A polygon can be created by the segments connecting the ordered vertices of a B ezier
curve.
In 2D: The number of intersections of a straight line with a planar B ezier curve is
no greater than the number of intersections of the line with the control polygon. A line
intersecting the convex hull of a planar B ezier curve may intersect the curve, be tangent to
the curve, or not intersect the curve at all. It may not, however, intersect the curve more
times than it intersects the control polygon.
In 3D: The same relation holds true for a plane.
Results : (a rough interpretation)
A B ezier curve oscillates less than its polygon.
The polygon's segments exaggerate the oscillation of the curve.
This property is important in intersection algorithms and in detecting the \fairness" of
B ezier curves.
(N. M.
Patrikalakis, Massachusetts Institute of Technology Cambridge, MA
02139-4307, USA, lecture 4 and 5, p.7)
Bezier curve (New)
Bezier curves and surfaces are credited to P. Bezier of the French car
firm Regie Renault who developed (about 1962) and used them in his software
system called UNISURF which has been used by designers to define the outer
panels of several Renault cars.
The Bezier curve is defined in terms of the locations of n +1 points.
These points are called data or control points. They form the vertices of what
is called the control or Bezier characteristic polygon which uniquely defines
the curve shape as shown in Fig. 4.44. Only the first and the last control
points or vertices of the polygon actually lie on the curve. The other vertices
define the order, derivatives and shape of the curve. The curve is also always
tangent to the first and last polygon segments. In addition, the curve shape
tends to follow the polygon shape. These three observations should enable the
user to sketch or predict the curve shape once its control points are given as
illustrated in Fig. 4.45. The figure shows that the order of defining the
control points changes the polygon definition which changes the resulting curve
shape consequently. The arrow depicted on each curve shows its parameterization
direction.
New definition is better than previous one.
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