Week 8 - Challenge 5 - Core & Cavity Design
DESIGN OF SWITCH BEZEL CORE AND CAVITY
OBJECTIVE: The main objective of this challenge is to performe draft analysis on given class A surface and to develop a final solid switch bezel part and perform the draft analysis on the solid part by using CATIA v5 software. Finally we have to design core and cavity for the switch bezel and to perform draft analysis on the core and cavity. A report has to be prepared by explaining about what is draft analysis and tooling axis along with core and cavity and add all the relevant images to the report.
DRAFT ANALYSIS
Draft analysis is a analysis which is performed on the objects or bodies in order to check the draft angle of various faces in a particular direction which is tooling direction.
Every part like sheet metal parts which are generated from a Press Tool or some forming tools, may be the plastic parts which generally come out from the plastic moulds and maybe the casting parts, all such kind of parts required some drafted face on the surfaces which are parallel to the tooling direction. If we don't provide drafts on the surface then it will stick to the mould surface and whenever the mould is in motion they will destroy the surfaces or also reduced the finishing of surfaces.
The Tooling Direction is basically the direction that the mold pulls apart. The mold is built in two separate pieces, basically. You have a Cavity side and you have the Core side. The Core pulls apart from the Cavity and that's the Dyeline or the Tooling Direction.
And the axis which represents the tooling direction is called tooling axis and selection of this is axis is a crucial step while performing the draft analysis.
CLASS A SURFACE:
In automotive sector, a class A surface is any of a set of freeform surfaces of high efficiency and quality. Although, strictly, it is nothing more than saying the surfaces have curvature and tangency alignment – to ideal aesthetical reflection quality, many people interpret class A surfaces to have G2 (or even G3) curvature continuity to one another.
Class A surfacing is done using CAD applications. Class A surface modellers are also called "digital sculptors" in the industry. Industrial designers develop their design styling through the A-Surface, the physical surface the end user can feel, touch, see etc.
In general CLASS A surfaces are crated using autodesk alias software.
CLASS B SURFACE: Class B surfaces are the secondary surfaces that you can see sometimes, but are less important, such as the inside of your glovebox, ash tray, etc.. These must be smooth and "error-free" as well, but are not held to the standards that class A surfaces are.
CLASS C SUFACE: The Class C finish allows more imperfections than Class A or B. Class C is often specified for interior surfaces not readily visible, surfaces that will be covered by another part when assembled, or surfaces which the Customer feels do not need to meet a high cosmetic finish.
CREATION OF TOOLING AXIS
1. First extract the base surface of the given class a surface and create a point at the centre of the surface.
2. Now create an axis system based on the point which we have created earlier
3. By using positioned sketch and YZ plane as a reference create a sketch and by using intersection command in sketcher workbench create an intersection as shown below,
4. Now create two lines which are passing through the intersection curve as shown below make them as construction element and using line commnd and type as bisecting create a bisecting line between the tw lines.
5. Create another sketch by taking ZX plane as reference and create another line as shown below,
6. By using bisecting line create a line by selecting the lines in the two sketches and name the resultant line as tooling axis line.
CHECK FOR TOOLING AXIS
We can verify thet the tooling axis which we have created is correct or not in a very simple manner. For that,
1. select the tooling axis which we have created.
2.now click on the normal view tab and if we see tha three walls in that view then we can say that our tooling axis is correct or else we have to modify the tooling axis.
DRAFT ANALYSIS ON CLASS A SURFACE
The class A surface after applying the colours to different surfaces looks as shown in below image,
1. Open the draft analysis tool and set the value of draft as 3 degrees and ensure the surface is in material mode in customize view tool bar.
2. Click on the compass command which is in the direction command and align the compass and our tooling axis properly and click on the lock symbol and just tap anywhere on the class A surface and we will gwt the draft analysis. The images of the draft analysis in different views are as shown in below figures,
ISOMETRIC VIEW:
FRONT VIEW:
SIDE VIEW:
TOP VIEW:
CREATION OF CLASS B SURFACE
The B surface of the part has three parts within the B surface, they are
- BEZEL REST SURFACE
- WALLS
- BASE SURFACE
BEZEL REST SURFACE:
1.For bezel rest surface extract the surface of the bezel rest from class A surface
2. Untrim the surface.
3.Offset the surface to a distance of 2.5 mm in downward direction.
WALLS:
1.Extract the three walls of class A surface.
2. Untrim the walls.
3. Extrapolate the three untrims and make sure they are extending with curvature continuity and propagation mode as point continuity.
4. Trim the walls to make a shape similar to the given class A surface and offset that to 2.5 mm in proper direction.
BASE:
1. Extrct the base and untrim the base.
2.Extrapolate the base and offset it to 2.5 mm and trim it with walls and bezel rest surface.
3. Apply fillets with proper radius and rename the last edge fillet as CLASS B SURFACE.
CREATION OF CLASS C SURFACE
1. By using boundary command create a boundary to the surface.
2. divide the boundary into four parts and sweep the surfaces.
3.Now extrapolate the edges where there are gaps and trim them and join them together in order to create a final CLASS C SURFCE.
Now after that join class A and class C and after that trim it with class B and it is like as shown in below figure,
By using close surface command fill the gap and create a solid, the views of solid are as show in below figures
ISOMETRIC VIEW:
FRONT VIEW:
SIDE VIEW:
TOP VIEW:
DRAFT ANALYSIS ON SOLID BODY
ISOMETRIC VIEW:
FRONT VIEW:
SIDE VIEW:
TOP VIEW:
DESIGN OF CORE AND CAITY
Before designing the core we have to design a surface which called parting surface with the component area for proper design of core and cavity.
DESIGN OF PARTING SURFACE WITH COMPONENT AREA:
1. First create a boundary on a class A surface and increase the thickness of the boundary for the puspose of clear visualisation.
2. Now extrapolate the boundary to the required distance
3. Trim the extrapolate with class C surface
4. Now trim the above trim with class B surface and the required parting surface with component area has been created, give it a nice colour
DESIGN OF CORE:
1. Draw a skech on the base plane which is the XY plane and make sure it is iso constrained and you have used positioned sketch
2. Now extrude the sketch
3. Trim the extrude with parting surface with component area surface
4. Create a boundary on top edge and fill the surface and join the two surfaces with join command
5. Now by using close surface create a solid body for core and change the colour and various views of solid body of core are given below,
ISOMETRIC VIEW
FRONT VIEW
SIDE VIEW
TOP VIEW
DESIGN OF CAVITY:
1. Extrude the same sketch what we have created for for core with respect to the tooling axis.
2. Trim the extrude with class B surface
3. Create a boundary on the bottom side and create a fill for that and then join the cavity body and fill surface
4. Now use the close surface command in part workbench and try to create a solid body. The various views of solid cavity body are as shown in below figure
ISOMETRIC VIEW
FRONT VIEW
SIDE VIEW
TOP VIEW
PARTING LINE:
A parting line, in industrial casting of molds, is the border line in which draft angles change direction. One can check the parting line in the mould or product which divides the two half, i.e; the core and the cavity of a molded part. It is sometimes a starting point for the mold parting surface.
To create a parting line simply make an intersection between CLASS A- CLASS C join and CLASS B surface.
PARTING SURFACE:
The parting surface of a mould are those surfaces of both mould plates adjacent to the impressions which butt together to form a seal and prevent the loss of plastic material from the impression.
To create a parting surface split the parting surface with component area withe the parting line.
CORE AND CAVITY ACTUATION:
Let us observe the below figure properly
We can observe that the core which is on the top will move towards the bottom side and the cavity which is on the bottom side moves toward the top sides and these two movements produces a cavity between them in which the molten plastic material is fed into form the surface. now in the bottom figure solid swith bezel is shown
PART NAVIGATOR
CONCLUSSION
Hence i have created core and cavity for the swith bezel and a well formated report has been prepared successfully.