This chapter will foreground the experimental work conducted to look into the consequence of metal organizing velocity on the backward-forward combined bulge procedure of polygonal and cylindrical cross subdivision cup saloon form components.. Subsequently, an rating of the extrude specimens has been done to analyze the influence of the procedure on the emphasis distribution in lead specimens.
The experimental process consisted of the followers: -
Material choice for bulge dice, clouts and workpiece readying.
Found. The chemical composings workpiece and for dice, clouts
Design and fabrication of dice of the backward-forward bulge and types
of Pistons used.
Determination of the backward-forward bulge parametric quantities.
Execution of the backward-forward bulge procedure.
4.2.1 Choice of the work-piece: -
The note stuff used in this survey for bulge procedure is ( 99.99 % ) commercially pure lead and its chemical composing listed in Table ( 4.3 ) . Lead can be used as a theoretical account for a figure of metals at different strain rates and temperatures because of similarities in footings of Stress-Strain curves. This is utile in the survey of flow metal in the forming procedure.
Equally good as its ability to re-crystallization at room temperature its composing is similar to the hot forming procedure for steel which leads to the absence of strain hardening in this metal. Lord has yielded emphasis, which varies in sum between ( 6-8 MPa ) and the temperature runing point is ( 327 °C ) [ 10. Lead is a extremely dense, corrosion opposition and really soft ductile stuff. As shown in figure ( 4-1 ) , A grid has been printed in the forepart of the as shown in figure ( 4-2 ) . Tip for mensurating the supplantings of each point after distortion by the burden required for bulge.
Figure ( 4-1 ) : the pure leadFigure ( 4-2 ) : he pure lead
Before printed grid printed grid
Properties of lead in item are given in table 4.1.The thermic belongingss of pure lead 99 % are as shown.
Table 4.1Mechanical belongingss of lead from the documents
YoungaˆYs Modulus of Elasticity
Thermal Expansion Coefficient
Table 4.2 Thermal Properties from the documents
4.2.2 Determination of stuff belongingss
In the present probe pure Lead ( 99 % pure ) is used as work stuff. Different belongingss of lead stuff like flow emphasis, clash factor, etc. are determined utilizing different compaction method. These belongingss are used in upper edge simulation utilizing FORTARN90. In compaction trial, a big sum of distortion can be achieved before break.
4.2.3 Compression trial
This is the simplest compaction trials in which a cylinder compressed axially between smooth platens. This gives the same output emphasis at a tensile trial with little strains when home bases are good lubricated. Friction coefficient at the die face additions as the strain addition a specimen spreads out. From compaction trial we flow emphasis of the stuff can be determined.
A lead solid cylinders with two halves 40mm diameter and 70mm length is compressed between good lubricated smooth home bases every bit good as in dry status to find the clash coefficient in greased and dry status both. Due to flux of material diameter additions as length lessenings. By turning operation excess stuff removed to acquire initial diameter. The trial is repeated three times and mean true emphasis vs. true strain graph is plotted from unit of ammunition note with cosine and taper dice are besides discussed in this subdivision.
Specimens chemical composing proving
4.2.4 Chemical composing of the metal.
The metal, which is used in this survey, is ( 99.99 % ) commercially pure lead. The chemical composings of this stuff as shown in listed in Fig 4.3which is found in the computing machine –controlled Iraqi Ministry of Industry and Minerals The State Company for Inspection & A ; Engineering, Rehabilitation ( SIER ) & A ; BY Central Organization for standardisation and Quality Control as shown in listed in fig 4.4
Fig.4.3 the list of concentrations of elements found within the pure lead specimen
Fig.4.4 the list of concentrations of elements found within the pure lead specimen.
4.3 Application of Grid
The grid can be applied to the specimens by the followers: -
Hand composing or scribing: The grids can be made on the specimens by manus or can be scribed by a crisp pointed acerate leaf. To cipher the strains in the specimen at all points each component of the grid will hold to be measured before and after striving. This method can be used for comparatively soft crystalline stuff like plastics.
Machine scribing: Grid can be scribed by machine utilizing governing engines for level and cylindrical surfaces. The single elements in the grid may be indistinguishable and measurings need be made merely after striving. Machine scribed grids are used merely when trials are to be carried up to tear.
Ink, pulling: Grid can be drawn with ink on theoretical accounts. The thickness of lines should be every bit little as possible to obtain more truth.
Rubber togss: For soft, porous stuffs, thin gum elastic togss of 0.2mm diameter can be glued by latex and strain measurings may be made after lading.
Photo grid method: Grid can be applied photographically by painting a light sensitive emulsion on the surface of the trial specimen, covering the surface with a maestro grid negative, exposing to strong visible radiation, and developing the end point print in the usual mode.
4.4 Procedure of work
Grid method is one of the methods of strain analysis, which is whole field in nature. In order to find supplantings and strain constituents at given points of randomly shaped surfaces a grid can be engraved on the surface to be studied. This grid acts as a mention component and the alterations that the grid experiences from the undeformed to the distorted conditions can be utilized to find either supplantings or strains. Two troubles are encountered which limit the usage of grids for mensurating distortions ; foremost, the strains to be measured are normally really little, and in most instances the supplanting readings are hard to do with sufficient truth. This is peculiarly true in stress analysis. However, this method is really much suitable for the survey of distortion in stuffs. Second, when the exposure of the grid web are magnified by the microscope, the images of the grid lines are normally ill defined presenting appreciable mistakes into the displacement readings. This method has the advantages that a photographic record of distortions covers the full field of the specimen. This record can be obtained for either inactive, dynamic elastic or fictile distortions. The strain was measured straight. The distance between the grid lines on the theoretical account was measured by a microscope by maintaining the magnification of microscope same before and after extruded. However,
the tried pure lead specimens exhibit extremely accurate consequences when the little elastic distortion can be ignored and merely fictile distortions are taken into consideration.to implement a grid of a known constellation upon the specimens.a computing machine –controlled CNC machine, which is operated and found in the Iraqi Ministry of Industry and Minerals –Engineering Qualification and Testing Affairs Division, is utilized in fig ( 4.6. )
Fig ( 4.6 ) the Computer –Controlled CNC Machine and, pure lead specimen with grid.
4.4.1 Description of the computer–controlled CNC machine:
The grids require some experience to derive in order to manage the computer-controlled CNC machine easy, therefore the device is consisted of the following chief parts
1-The Operation-panel As shown in fig ( 4.7 ) . The operating panel for the computer-controlled CNC is responsible for all the plans ( run by the DOS operating system ) needed to put to death the machining procedure onto the workpiece and for organizing scenes.
Fig ( 4.7 ) The Operation-panel
2-Machining tool: As shown in fig ( 4.8 ) , The CNC MACHINE has some jaw where the machining tool can be fixed, and this is directed by utilizing the co-ordinate scenes found in the operation panel in order to get at the needed machining operation.
Fig ( 4.8 ) of Machining tool
Pure lead specimen requires some surface finish skyline trial to accomplish before grid execution processes a machining tool that is attached to a dial gage holding an truth about 1.
The grid method was used to cipher the supplanting in the X-axis ( u ) and in Y–axis ( V ) . The dimensions of the grid were ( 70 mm?40 millimeter ) and the length of the square is ( 2mm ) as shown in figure ( 4-9 ) .
Fig ( 4-9 ) the scan of pure lead specimen after
The grid was photographed before and after backward-forward bulge of the pure lead specimens and the measurings of the supplantings was taken by microscope so scan it for all the specimens. Then the strains at the surface squares gird were calculated in the specimen the strains in the specimen at all points each component of the grid will hold to be measured before and after striving. Finally, the consequences and different boundary conditions were compared with upper edge solution consequences The grid was photographic before and after the rhythm of the sample and the measurings of the supplantings was taken by microscope for all the samples In add-on to the usage of the plan compared to the knock -dimensional images Photography are taken before and after distortion and compare the consequences with theoretical consequences as shown in fig ( 4.10 ) for some specimens before and after bulge
Fig ( 4.10 ) shown The specimens of lead after bulge with hexangular clout
Fig ( 4.11 ) shown The specimens after bulge with round clout
Fig ( 4.12 ) The some specimens after bulge
4.5 The experimental work: -
Experimental surveies are carried out with a position to compare the experimental consequences with the theoretical 1s obtain from proposed method of analysis, and upper edge method are carried out from commercially machine available for bulge of The dice with cone angle of ( 120 ) and polygonal clouts ( hexangular ) .the machine have three regardful velocity to compression the stuff at ( 0.002,0.00 3,0.004 ) m/s which are used in our survey, Three decrease countries of dies ( 30 % , 0.50 % , ) are used a cylindrical and hexangular Piston diameters of 40 millimeters and 30 millimeter as shown Fig ( 4-8 ) , crown out of the metal and a diameter of 25mm,15 millimeters and 10mm slots so have been a rounding each diameters of the Pistons. Experiments are done for both backward-forward bulge procedure. Commercially available lead is used for workpecies experiment when used low metal steel for organizing dice of the backward-forward bulge procedure. An bulge apparatus for laboratory experimentation is designed and the chief of the of the backward-forward bulge theoretical account, consists of four parts ; viz. , the container holding a round chamber, the squeeze outing clout, bulge dice holder and the back uping block for the assembly.
Fig ( 4.13 ) shown hexangular clout and round clout
4.6 Die design and fabrication
The sets of backward – frontward bulge dice ( at three different per centum country decrease ( 0.30,0.50 ) % . ) , are employed for experimentation.by two allow diameter dice 15mm, 25mm with bulge procedure lead, and a cylindrical Piston diameters of 40 millimeters and 35 millimeter and 30 millimeters piston hexangular diameters of 40 millimeters and 35 millimeter and 30 millimeter and for present analysis. The inside informations of the bulge dies are presented in Figures ( 4.12 ) & A ; ( 4.13 ) .
Fig ( 4-14 ) OF The parts of dice
Fig ( 4-15 ) OF The parts of dice
Have been utilizing AUTO-CAD plan for die design as shown in fig ( 4-10 ) and so was manufactured by the workshops of the Iraqi Ministry of Industry and Minerals The State Company for Inspection & A ; Engineering, Rehabilitation ( SIER ) utilizing this operating machine and lathe in add-on to making high- preciseness surface about 0.51?m after it has been carry oning minutess Calories appropriate for the templet and before used.
Fig ( 4-16 ) dicedesign by AUTO-CAD plan
Figure ( 4-17 ) OF The some parts of dice after design
Figure ( 4-18 ) OF The some parts of the dice after fabrication and surface coating operations
4.7 Chemical composing of the metal of the dice parts.
The metal, which is used in this survey, commercially low metal steel. The chemical composings of this stuff as shown in listed in Fig ( 4.-16 ) which is found in the computing machine –controlled Iraqi Ministry of Industry and Minerals The State Company for Inspection & A ; Engineering Rehabilitation ( SIER )
Figure 4.19 the list of concentrations of elements found within low metal steel used to decease