This week the team developed step by step, the methods thatwill be used by the group to be able to manufacture the rivetsand riveted together, detailing and justifying the proceduresadopted and the decisions taken skins for components. In thisscenario the team has the objectives of:
- Identify the variables of the casting process.
- Determine the casting method to be used
- Determine the model and mold dimensions
- Describe the process of fitting together.
First was determining the method of manufacture of rivets,for it was taking into account quantity of parts to beproduced; Foundry project; required tolerances; degree ofcomplexity; metal specification; desired surface finish,among other factors. The team chose the metallic moldcasting method of rectangular geometry of the twoparttype, taking into account the ease of operation, thepresentation of greater uniformity, better surface finish,closer tolerances and best mechanical properties of rivet.
Furthermore, the procedure of manufacture of rivets needsto take into consideration the size of the rivets, plus thevariations inherent in the casting process. Because of this itwas necessary to consider the contractions present in thealloy solidification period. Second VERRAN, 1986, thecontractions during the cooling process of the material canbe of three different types depending on each Leagueconsidered: NET contraction (ΔVl), (ΔVsol) solidificationcontraction and contraction solid (ΔVs). Liquid and settingcontractions usually can be corrected with riser andcontraction solid can be controlled by a more appropriatedesign of the play or finish treatment in case of tensionsresiduiais.
Solid contraction is necessary to calculate volume of solidrivets and compensate in their dimensions. For it was used5.7% contraction factor of aluminum (VERRAN, 1986).Already the sizing system risers, can be done via the Methodmost widely used method of the modules, based onexpression of Chvorinov, where would be the break-up ofthe setting time with solidified thickness.
Based on calculations developed by team was foundappropriate dimensions of metal mold design to compensatefor the contraction of solid metal.
For the body of the rivet:
For the rivet head:
Then were determined the dimensions needed to compensatefor risering liquid contraction and solidification. the valuesfound were:
Riser height: 31.8199 mm
Risering diameter: 7.0358 mm
Risering diameter: 7.0358 mm
3D CAD MODELS AND MECHANICAL DRAWING
With all the defined dimensions, it was possible to develop themetal mold design in CAD, as you can see in the picturesbelow:
Figure1: Isometric view permanent rivets mold.
Source: own team.
Figure 2: Technical Details of mould base of rivets
Source: own team.
Figure 3: technical details of mould block of rivets
Source: own team.
Figure 4: permanent rivets mold.
Source: own team.
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