Pattern Shop1 by huangyuarong

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									  CENTRAL WORKSHOP
  THAPAR UNIVERSITY
   PATIALA, PUNJAB




WORKSHOP REPORT :
PATTERN SHOP



   Submitted By :

        NAME: NITISH WADHWA
        Roll No.: 10703072
        Group :F3
        BE 1ST YEAR
              INTRODUCTION
- A pattern may be defined as a replica or fascimile
  model of the desired casting which, when
- Packed or embedded in a suitable moulding material,
  produces a cavity called mould.
- This cavity, when filled with molten metal, produces
  the desired casting after solidification of the poured
  metal. Since it is a direct duplication, the pattern very
  closely conforms to the shape and size of the desired
  casting, except for a few variations due to the necessary
  allowances. The ways in which a pattern differs from an
  actual component are:

- It carries an additional allowance to compensate for
  metal shrinkage.

- It carries additional allowances over those
  portions which are to be machined or finished
  otherwise.

- It carries the necessary draft to enable its easy removal
  from the sand mass.

- It carries additional projections called core prints, to
  produces seats for cores.
      FUNCTION OF A PATTERN
- The main functions of a pattern are:-

- To produce the mould cavity of appropriate shape and
  size in which the molten metal can be poured to obtain
  desired casting.

- To produce seats for cores in the mould in which cores
  can be placed to produce cavity in the casting. These
  seats in the mould are called core prints.

- To establish to parting surfaces and lines in the mould.

- To establish distinct locating points in the moulds , of
  which the corresponding points on the casting are used
  as reference points, for checking the casting dimensions
  and relative location of machined and other surfaces.

- To minimize defects in castings and cost of casting.

- To enable production of greensand or rammed up cores
  with in the mould itself.



                          JOB
Preparation of a pattern for casting of square pipe
                    MATERIAL
A Wooden Piece



                        TOOLS

Jack plane, mortise chisel, firmer chisel, tenonsaw, tri
square, marking gauge, steel foot sole etc.

The principal types of these tools are described below:

PLANNING TOOLS : Apart from the common types if
planes viz., jack plane, trying plane and smoothing plane,
used in carpentry, the following are the other planes used in
pattern making :

BLOCK PLANE: It is a small and light-weight plane
carrying an adjustable single blade. It is used by only one
hand and a popular size is 15cm long having a 40 mm wide
blade.

RABBET PLANE: It is used for planning into corners
and against perpendicular surfaces. Its size is
determined by the width of the blade.

ROUTER PLANE: It carries a chisel-like blade and is
used for planning the bottom surfaces of small Grooves and
other depressions.
CIRCULAR PLANE: It carries a flexible bottom face
made of steel which can be adjusted to any curvature to
plane different sizes of convex and concave surfaces.

PLOUGH PLANE: It is a type of moulding plane and is
Used for cutting grooves of different shapes and sizes on
the edges.

SAWING TOOLS: A saw is a multi tools made up of thin
sheet attached with a wooden handle chopping saw is used
for cutting quick or sharp curves either internally or
externally.

FIRMER CHISEL: It is a general purpose chisel used to
finish inside grooves. It has various sizes of cutting edges
depending upon work to be done.

IRON JACK PLANE: This is used for better finish. It is
made of cast iron with a wooden handle at back.
                PROCEDURE
1. Plane the surface of given wooden piece with help of
   jack plane and check with tri square whether surface
   straightened or not.
2. Now keeping it as reference, plane other surfaces such
   that its breadth 41mm and length 20.5.
3. Now cut from middle with help of tenonsaw.
4. Mark a point on centre of one piece and make two
   points from point centre at 20mm each.
5. Make three holes at marked points and blind hole at
   other piece at the same location.
6. Prepare dovel pins and fix it through holes such that
   two pieces fit completely.
7. Make 5mm marks on faces and cut out side position
   till depth of 20mm.
8. This will produce core prints. Make this taper.
9. Give final finishing with sand papers.
            TYPES OF PATTERN
Depending upon casting required pattern are classified as:

SINGLE LOOSE AND SOLID PATTERN: They are
complete in themselves and are not dependent on any other.
They have limited use.

SPLIT PATTERN: These are split along parting surfaces
so that one part can be placed in cope and other in drag.

MATCH PLATE PATTERN: Cope and drag are
fastened to a plate with a help of pins.

COPE AND DRAG PATTERN: These are to speed up
production where cope and drag sit on each other easily and
are rammed at same time.

 GATED PATTERN: They have an added detail design to
 form gates and runner. Sethal pattern are held together
 with this gating device.

 SKELETON PATTERN: They consist of wooden frame
 and strips, these are employed for large.

 SWEEP PATTERN: These are used in mainly mould of
 large symmetry circular cross-section to effect saving in
 time, labour and material.
           PATTERN COLOURS
The following practice will serve as useful a guide both
for pattern and core boxes:

1. Red-surfaces to be machined.

2. Black-surfaces to be left unmachined.

3. Yellow-core prints.

4. Red stripes on yellow base-seats for loose pieces.

5. Black stripes on yellow base- stop offs.

6. Clear or no colour-parting surfaces.


                 REFERENCES

  A course in workshop technology.
   (vol.1 manufacturing process)
   by-B.S.RAGHUWANSHI
  WWW.WIKIPEDIA.COM
  Manufacturing Processes by-DEGARMO

								
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