Week 9 - Attachment Feature Creation (Ribs & Screw Boss) - Challenge 1

Creation of Door Handle Part

Aim:

To Create the Door handle along with Ribs & Screw bosses from the given Class A surface.

Procedure:

Given Class-A Surface

Step 1: Class-A Draft Analysis

First check the given Class A surface which clears the draft analysis or not.

Step 2: Creating Tooling Axis

For checking the draft analysis need to create the "Tooling Axis" is our first step. Therefore we check which direction (X, Y & Z) will helpful to create "Tooling Axis"

In X-direction the view of the given surface is not clear, in that view point we can't create the door handle

In Z-direction also we can't see the full surface

In Y-direction, we can able to see the complete surface and it's easy to produce the part along Y-direction. Hence we consider that "Y" is our tooling direction

Tooling Direction – "Y"

 

Step 3: Extract the flat surface in the given Class-A surface and using Point command > On Surface we mark the point on the middle of the given surface.

Then using Line Command > Point and Direction, select the Middle point of the surface and direction is "Y". Rename the line as "Tooling Axis".

Step 4: After creating the tooling axis, now we are going to perform the Draft analysis for Class-A surface. First change the View mode option as Customize view parameter and select the material option.

 

Step 5: Select Feature draft analysis command, Click the compass icon, drag and place the compass along the Tooling direction and lock it. Then select the Class-A surface, and inverse the draft. To enable the Colour scale icon under the Display tab.

In the colour scale, initially give the 3 degree of draft Class-A not clear the draft

 

Instead of 3 degree, if we give 0.5 degree as a draft angle, given surface clears the draft analysis. In this case, 0.5 degree is the minimum draft angle for class-A surface.

Draft Angle for Class-A surface – 0.5 degree.

Step 6: After the draft analysis, Need to create the B surface. Usually in plastic parts the B surface  is 2.5 to 3mm distance from the class-A surface. In the particular challenge the offset value is not given, so we consider the offset value as 3mm.

Offset value of B surfcae – 3mm

Offset the given class a surface at an distance of 3mm. Some portion is missing while performing the offset.

Using Multisection command we recreate that part and join with the offset surface. Now get the B Surface 

Step 7: Creating C Surface

For creating the C surface, take a reference from the A-surface and using sweep command > With Reference surface. Select the entire Class A boundary and draft angle is 90 degree at an length of 4mm.

Step 8: Now using Join command to join the sweep and Class A surface, and select the Sub – element to remove tab remove the marked faces.

Why because the particular surface is perpendicular to the Tooling axis, so in order to clear the draft analysis we have to create the surface in Sweep > Draft direction Technique.

Finally using trim command joins the class A & Class C surface

Step 9: Creating final part (door handle)

Extrapolate the Class B surface and trim that surface with Class A+C surface to get the final part. Now check the part is a closed one or not? Select the Boundary command and pick the final part, error message will pop-up, this mean the given body is completely closed no open boundary. Now name it as Door Handle.

Step 10: checking draft analysis for final part.

Follow the same step for the class-A surface draft analysis. When we give 3 degree of draft some portion are not clear because the given Class-A surface is not clear the 3 degree draft, so it have some drafting issue in the Class-A surface itself.

Now change the draft angle is 0.5 degree it clears the draft but however some portion have no draft.

To overcome this problem remove such portion and recreate the surface using sweep command using reference surface method. While performing draft analysis increases more number of areas as negative and no draft area.

Again tried to recreate the problem surface using sweep option but this time using profile type 1 and reference surface method, the given inputs are entered but still the surface not clear the draft analysis.

Finally decided the combination of Reference surface method and Draft direction method will give the maximum clearance in the final output. So i take this surface as my input and perform the draft analysis at an angle of 0.5 degree.

Step 11: Create Part Body

Go to Part workbench using Close surface command select the door handle final output make it as a complete closed part body.

 

Step 12: Create Ribs

For creating Ribs, should follow some design constrain. Based on this condition ribs created

First create a geometrical set and name it as "Ribs", then draw the sketch on the inner side of the part (which mean Part B)

Extrude the sketch at a height of 15mm, why because height of the Ribs is 5*T (Thickness of the component).

In this challenge the thickness is 3mm, so 5*3=15mm is out Rib Height.

Rib Height: 5*3 = 15mm

Then create a Body and using thick surface command thicken the Rib at an amount of 1.2mm. Have condition in rib Thickness, it should be 0.4*T.

Rib thickness: 0.4*3 = 1.2mm

 

Then using union trim option join the Ribs to the part body of Door handle. Select all the faces of the Ribs and give draft at an angle of 0.5 degree. This is the minimum draft angle for Rib.

Minimum radius is 0.25mm is also given to the all sides of the Ribs. Hence all the conditions are followed to make the Ribs

 

Step 13: Rib Root thickness

Now analysis the Rib root thickness, for that creates the plane and takes an intersection. In that obtained intersection 2-D profile extract the Ribs base fillet surface both side and using tritangent circle option create the circle and measure the radius 3.205mm.

Step 14: Screw Boss Creation

For creating the screw Boss, should follow some design constrain.

First draw the sketch on the B-surface of the product. In this case the dimension of the screw hole is not given, so we consider the screw hole dimension as M6 (i.e: 5.2mm).  Draw the inner circle at a dia. Of 5.2mm and the outer screw boss circle radius is 8.8mm. Here we follow the one of the screw boss design condition.

Wall thickness of the single side of the screw boss is 0.6 * T, apply the condition to draw an outer dia.

Wall thickness: 0.6 * T

0.6*3 = 1.8mm Single side wall thickness

Double side Screw boss wall thickness: (Single side thickness * 2) + screw hole dia.                                                                         (0.8 * 2) + 5.2mm                             Screw boss Thickness = 8.8mm

 

And make the distance between the two screw bosses at a distance of 30mm.

Now using the pad command create a solid body at a height of 15mm, Add the Screw boss to the main part body and follow the design constrain have to give the draft angle of 0.5 degree to the screw boss and also give the fillet radius is 0.25mm.

Step 15: Draft analysis for the Door handle with Ribs & Screw Boss.

Follow the same set of procedure and perform draft analysis of the end component. Now we clearly see at an angle of 3 degree and 0.5 degree of draft the component no clear the draft analysis.

We continuously check and reduce the draft angle for 0.48 degree the entire part will clear the draft analysis test.

Draft analysis for the end product = 0.48 degree

 

Conclusion:

Based on the given Design feature of Class A, Ribs & Screw boss we created the End part Door handle with Ribs and Screw boss.

Perform the draft analysis in every necessary stage and made necessary changes in the design to clear the draft analysis.

Ribs & Screw boss are fixed in the door handle without violating the design constrain.

 

 

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