Week 10 - Challenge 3 - Door Trim Lower with Engineering Features

 

DESIGN OF HEAT STAKES AND LOCATORS

 Introduction

      Heat staking also known as thermoplastic staking is the process of joining two dissimilar materials together. In heat staking we use local heating and cooling to raise the temperature of plastic components and allow plastic reforming to be carried out. This reforming can be used in a wide variety of applications. 

      Applications range from staking plastic boss’s for assembly of car door panels to joining PCB’s to plastic housings.The locators helps to restrict the movement of the component in different directions. The benefits of this technique include; no vibration damage, no particulates, the ability to stake metalized coated applications and the capability to stake in difficult to access or restricted areas.

There are 12 degrees of freedom for any part in fixture design. 4-Way Locators are designed to arrest 4 degrees of freedom in X+,X-,Y+ and Y- directions. 2-Way Locators arrest only 2 DOF in either X+ and X- or Y+ and Y-. Generally, 3-2-1 rule is applied to completey constrain a part with 2 4-Way and 1 2-Way Locators.

 

 

 

 

 Figure1 :Heat stakes used in door trim

 

 

AIM

The main aim of this challenge is to create an engineering feature called heat stakes and locator by  creating a solid body of 'Door Trim Lower' with the help of the closed surface method by using the 'Generative shape design' workbench in CATIA V5. Performing the 'Draft Analysis' on the solid part body of the Door trim.

OVER VIEW 

Initially, we need to offset the given Door Trim OF  class A surface in the inner direction to the required thickness (here the thickness is 2.5mm). After that, we need to close the patches on the offset surface of the bumper, the patches are formed due to the fillets on the Class A surface. Once all the patches are closed properly join them together to make a proper class B surface and now sweep the boundary of the class  A surface to trim with the class B surface to make a closed body.

By using the closed body command in the PARt workbench we can get the solid body to form the closed surface of the Door Trim. Now, I create the Heat stakes and Locators by considering all the design parameters. After creating all the B-side features on the solid part body of the door trim, I performed a draft analysis for it to check whether all the surfaces are drafted properly or not (The draft angle for the plastic component is 0.5deg to 3deg).

 

TOOLING AXIS

To create the tooling axis, I extracted a surface from class A and created a point in the middle of the surface by using the point command and created a line at that point through the x-axis. Now, I performed a draft analysis check from that line whether the created tooling axis is in the correct position or not. If in the draft, analysis check the surface highlighted with green colour on both sides of the surface the tooling axis is in the correct position and direction.So we can fix this as the final tooling direction.Its is actually a trail and error method.

 

 

 

Figure 2 :Tooling axis for class A surface.

 

 

DRAFT ANALYSIS FOR CLASS A SURFACE

We do perform the draft analysis check for class A surface before we make solid and creation of B-side features. Initially I align the compass to the tooling axis and I gave a 3 deg draft angle for the green colour in the colour bar. If the surface is highlighted in green colour the draft angle is given properly for class A surface. If the class A surface is not highlighted fully in green colour, that might be the reason for the draft angle of the class A surface is wrong.

 

 

  Figure 3 :Draft analysis of class A surface.

 

 

CLASS B SURFACE

To create the class B surface, offset the class A surface inside as per our thickness requirement (here the thickness is 2.5mm, so I offset the class A to 2.5mm inside). Once the offset is created, we can observe some patches on the offset surface by taking the boundary for the offset surface, those patches are formed due to the fillets on the class A surface. We need to cover those patches with the help of the multi-section surfaces command by extracting the patch boundaries.Then joining the multi sections with the surface to make it continuous. Once all the patches on the offset are covered properly join all the patches with the offset surface, to get the replicated surface of the class A surface.

The surface is checked for irregularities by using boundary command and made sure that no irregularities are found.If found we have to concentrate on that area.

The fillet is measured from the class A surface and the offset is compensated in the class B surface fillet.The fillaet  of class A - 2.5 is given to  the class B surface.

 

 

   Figure 4 :Offsetted surface from class A surface.

 

  Figure 5 : Surface extracted seperately.

 

  Figure 6 : Fillet measurement.

 

 

 Figure 7 : Final class B surface..

 

 

 

CLASS C SURFACE

 Here we can use class A surface to create class C surface. The regions are divided into different boundaries and sweep command is used .In the areas where sweep is difficult we can use multi section surfaces. Give adequate length for the sweep to form a good surface for the multisection surfaces to form and join the surface with about .003 mm gap which is the maximum. After joining the C surfaces together we can make the A and C join 

 

 

 Figure 8 :  class C surface.

 

 

 

 

  Figure 9 : Final class C surface

 

 

 A  AND C SURFACE JOIN

Here we use class A surface and class C surface to join each other with out any gaps and irregularities ,normally no irregularities are found.

 

 

 Figure 10 : A and C surface join

 

 

 

CLASS  B  SURFACE  EXTRAPOLATION

Here we can extrapolate the b surface to further extend and beyond the C surface ,so that we can trim the surfaces together to form a closed surface with good boundaries.

 

 

  Figure 11 : B surface extrapolated.

 

 

FINAL TRIM

Here we can trim together the surfaces of extrapolated B and A and C surface join to form the final trim with good boundaries.

 

 

   Figure 12 : A and C surface join and B surface extrapolated.

 

FINAL TRIM

 After trimming the surfaces we can get the final trim.

 

 Figure 13 : Final trim.

 

 

 Figure 14 : Final trim.

 

CLOSED BODY

Here we can use the final trim to create the closed body, by using close body surface from the part work bench.WE will be getting a closed body part.

 

  Figure 15 : Closed body part.

 

HEAT STAKES CONSTRUCTION

Firstly we need to arrest the part in minimum of 2 degrees of freedom and also need to give the first point of contact between the part and sockets.

So we need to construct locators at probably at the ends.

There are two types of locators 2 way locators and 4 way locators.

 

       Figure 15 : 4 way locators.

    Figure 16 : 2 way locators.

 

 

2 WAY LOCATOR

 

    Figure 17 : 4way locator sketch .

 

    Figure 18 : Padding the 4 way locator sketch for a particular length exceeding the part.

 

 

 Figure 19: Drafting  the part.

 

 Figure 20: Chamferring the part.

 

 

 Figure 21: union trinning  the part.

 

 

HEAT STAKES

 

Heat stakes are created by drawing the sketch with two circles of diameter 5 and 7 mm.

 

 Figure 22: Sketch drawn for heat stakes.

 

 

 The Sketch is then padded for apporximate length and ensure it is beyond the A surface

 

 Figure 23: Sketch drawn is padded for making heat stakes.

 

After padding the body we can give the draft to it .The draft given is 0.5 

 

 Figure 24 The Padded body is drafted.

 

After giving the draft we can give fillets to the body minimum opf 0.2mm

 

Figure 25 The Fillet given to the body.

 

After giving the fillets we need to transfer the body to the given points and union trim them.The body is copied and paste special is used in which (result with link) is used and traslation tool is used by point by point option.

 

The bodies  are then union trimmed,The faces to keep is given are the portion above the A surface.

 

Figure 26 Union trimming the body the body.

 

An additional element called support rib is given to the heat stakes for a good support.

 

Figure 27 Sketch for support rib

 

 

 

 

Figure 28 Padding for support rib

 

 

 

 

 

Figure 29 Drafting for support rib

 

 

Figure 30 Fillet given for support rib

 

Figure 31 Union trim given for support rib

 

 

 

DRAFT ANALYSIS OF THE DOOR TRIM PART

 

Figure 32  Draft analysis of the door trim part at 2.9 degree draft angle.

 

 Figure 33 Draft analysis of the door  part at 2.8 degree draft angle.

 

 

Figure 34 Draft analysis of the door  part at 2.8 degree draft angle.

 

 

 

Figure 35 Draft analysis of the door  part at 2.8 degree draft angle.

 

 

 

 

 

 

 

 

 

DRAFT ANALYSIS OF THE DOOR TRIM PART COMPONENTS (HEAT STAKES ,LOCATORS,AND RIBS)

 

Figure 36 Draft analysis of the door  part at 0.45 degree draft angle.

 

Figure 37 Draft analysis of the door  part at 0.48 degree draft angle.

 

 

Figure 38 Draft analysis of the door  part at 0.48 degree draft angle.

 

 

 

 

DIFFERENT VIEWS OF THE PART 

 

 

Figure 39 Front view of the part.

 

 

Figure 40 Rear view of the part.

 

 

 

Figure 41 Side view of the part.

 

Figure 42 Top  view of the part.

 

 

Figure 43 Bottom  view of the part.

 

 

Figure 44 Isometric   view of the part.