cad (assignment ii)

7/31/2019 CAD (Assignment II)

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Technological Educational Institute of Piraeus

MSc ADVANCED INDUSTRIAL AND

MANUFACTURING SYSTEMS

Module: Integrated CAD/CAM

Assignment:

CAD Practical Work Design of an Axial Fan

Module Leader: Prof. Dr.-Ing. Constantinos STERGIOU

Students Name: Georgios G. ROKOS

Students Signature: ___________________________

Date: 14/06/2011


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Technological Professional Institute of Piraeus

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This paper has its origins in the Integrated CAD/CAM Module of the MSc inAdvanced Industrial and Management Systems, undertaken at the

Technological Educational Institute of Piraeus, in cooperation with the

Kingston University, under the aegis of Dr. Constantinos Stergiou.

The assignments main goal is to trace the particularities of Solidworks

modeling process. For this purpose, the development of an Axial Fan

Assembly is explicitly illustrated, part-to-part, focusing on unexpected issues

and errors that needed to be resolved. Information about the Assemblys

form have been either distributed by the modules leader or attained from the

web.

The paper presents the features and the sketching tools and highlights the

limitations of each one of them in practice.

Moreover, this assignment revolves around Solidworks design intent.

Following the conclusions of the Axial Fans modeling process, an attempt is

made to evaluate the intelligence of the program. Being a parametric,

history-based CAD system, Solidworks is expected to foresee a range of

interventions and facilitate or even drive its users.

Last but not least, a drawing file, after a part of the Assembly, is included.

All the deductions recorded in this paper result from Solidworks usage by a

novice CAD user.

Hopefully, this paper will be a pleasant experience for its readers.

Georgios Rokos


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PART I

1) Creating the HubThe Hub is a part that was already provided in the Assembly.igs file. By right clicking on a

hub in the History Tree, on the left side of the screen, it was possible to open the part andview its dimensions.

Figure 1 displays the procedure followed to open a Hub part from the assemblys file. All

Hub parts are supposed to be identical. Figure 2 illustrates the selected Hub part.

Figure 1: Opening a random Hub part

Figure 2: Viewing the parts dimensions


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Having opened and measured the given Hub part, which will be referred to as Hub* from

now on, the new Hub part could be developed. However, in order to commence sketching,

a starting point for the first line of the sketch was required. This begot the measurement of

the distance between the centerpoint (origin) of the Assembly and the starting point of the

Hub*.

Having in mind that a short of Revolve Boss Base feature would follow, so as to accomplish

the circular result of the given assembly, mandated from the beginning the specification of a

referential point upon which the circular formation would be developed. By selecting

Window from the top of the screen, the transition from one file to the other has been an

easy task throughout the modeling process.

Figure 3: Measuring the distance of the Hub from the center point of the Axial Fan


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Figure 4: Sketching the first line

Since the sketching plane selected was the Front Plane, the first line should be aligned with

the X-axis. Figure 4 illustrates how the dimensions of the lines were inserted during the

development of the part. All the dimensions of the .igs model were to be multiplied by 0.78,

the given scale factor.

The second line, which was supposed to be coincident to the first one, was drawn from the

ending point of the first line.

After inserting the dimensions and the angular course of 150 the Fillet Sketch tool was

selected. The radius selected was that of 10, same as Hub*, because the implication at that

point was that maintaining the curvatures of the primary model would result in the desired

result.

The latter altered the dimensions of the first line. The fillet would start from a point on the

left of first lines ending point, shortening thence the dimensions of the first straight line. As

a result, the dimensions of the straight part of the first line needed to be reinserted (see

Figure 5).

The same issue occurred on the straight part of the second line and was dealt with re-

dimensioning as well. The distance between the fillets starting and ending point was also

inserted in alignment with the scale factor of 0.78 without causing any trouble for the

moment.


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Figure 5: Correcting the fillet-caused modification

Post to the completion of the first fillet and the second line, the third line and the fillet

merging it with the second line were sketched. The third line was parallel to the first one and

drawing it alongside the automatically projected (by the system) line triggered a parallel

relationship between the X-axis and the third line. Namely, the line was automatically

constrained as horizontal within the right plane. Since the dimensions of the lines and thefirst fillet were correct, the angular relationship between the second and the third line was

locked by itself.

The sketching of the fillet caused a problem which also highlighted a previous omission. The

system would not accept the co-existance of the radius 10 and the distance between the

fillets starting and ending point (multiplied by the s.f.). However, it would accept a 7.8

radius for that distance (viz 4.04 mm). The automatically implemented Horizontal

constraint for the third line restricted the application of radius 10 concurrently with the

calculated dimension of 4.04mm. Figure 6 demonstrates the course of the third line had the

horizontal constraint not been implemented. Subsequently, the system indicated the errorin the radius of the first fillet as well.


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Figure 6: Direction of the third line without the Horizontal constraint

Figure 7 depicts the complete, corrected sketch of the new part Hub.

Once the sketch is complete, the Revolved Boss/Base feature may be selected to create the

part. It is already known from the .Igs file that 12 Hubs form a circular assembly of hubs.

Thus, by imputing the equation 360 (the sum of of a circle) / 12 (the number of hubs) the

system will automatically calculate the dimensions of the Hub part.

The Thin feature determines the width of the new part. By imputing the equation 3 (the

width of Hub*) multiplied by 0.78 (the scale factor), Solidworks calculated the proper width

of the Hub.


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Figure 7: Complete sketch of part Hub

Figure 8: Determining the Revolve-Thin feature

Following the formation of the Hub part, the holes were left to be modeled. Figures 9 and10

present the measurement of the dimensions and positions of the holes.

Solidworks demonstrated by itself the midpoint of the upper edge of Hub* when the mouse

pointed at the edge. Thus, there was no need to sketch ancillary lines to trace the midpointin that occasion.


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However, an ancillary centerline was needed to assure that the midpoint of the upper circle

was indeed in the middle of the opposite edges of Hub*.

Figure 9: Calculating dimensions and position of upper hole.

Figure 10: Measuring positions and dimensions of bottom holes

After measuring the positions and the dimensions of the holes in part Hub*, it was easy to

sketch the holes on the surface of the new part Hub, taking into account the scale factor. As

shown in Figure 10, centerlines were designed to facilitate the positioning of the holes.


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One of the two bottom holes was sketched using the Mirror option. Mirroring a feature or

sketch entity necessitates a third entity of reference so as to determine the position of the

feature or sketch that is to be generated. A centerline acted as line of reference at that

point.

Figure 11: Sketching and mirroring holes

When the circles of the holes were sketched upon the surface of Hub, the Cut-Extrude

feature was utilized to generate the subtraction of material. The system understood by

itself the direction of extrusion.

During the positioning of the holes on Hub, a miscalculation led to a failed assemblage later

on. The error is explained later on.


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2) Creating the BladeTo create the new Blade part, Blade*, taken from the fan assembly.igs file, was used as

pattern. This time, the dimensions were not converted directly during the modeling process.

The part was modeled in the same dimensions as its pattern and the Scale feature was used

at the end to adjust the model as a whole to the given Scale factor.

To facilitate the development of the part Blade, a .sldprt part was provided as a construction

basis. The latter consisted of sketches of curves at three different parallel planes.

Figure 12: The construction basis

The first step to model the new part was the measurement of the length of Blade* so that

the distance of the parallel planes could be adjusted. However, the prototype had a curved

starting and ending edges lengthwise. Thus, the curvatures of those two edges also needed

to be assessed (Figure 13).

After the dimensions and the curvatures were calculated, they had to be implemented into

the new part. The distance between the planes and their containing sketches was adjusted

and the Loft feature was applied to add material between the sketches (Figure 14, ) followed

by the sketching of Centerpoint Arcs to apply the Cut-Extrude feature and create the

requested curves in the opposite edges of the Blade (Figure 15).

To design the curves, a parallel plane to the Top one had to be inserted (Reference

Geometry), since the latter bisected the lofted material.


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Figure 13: Measurement of dimensions and curvature

Figure 14: Applying the Loft Feature


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Figure 15: Cut-Extruding the opposite edges

In the middle of the front edge of the Blade, a circle needed to be sketched so that a

cylindrical component could be generated. The Extrude Boss-Base feature would add

material to the circle.

Figure 16: Generating the cylindrical component

The Fillet feature would blunt the edges of the cylindrical part. To assess the mm of Filletsapplication, the straight lateral line of the cylinder in Blade* was measured.


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On the front side of the cylinder, two parallel lines were sketched, both at a 20 accidence

compared to the X axis. The distance of the lines would be 25 mm while each one of them

would have equal distance from the center point of the cylinder on the Y axis. The two edges

would be laterally united on their sides through the 3 Point Arc sketch tool, following the

course of the cylinder, forming a closed sketch (Figure 17), ready to be extruded.

Figure 17: Closing the sketch

After the extrusion, two parallel lines were sketched on the edges of the new formation toremove material through Cut Extrude, offset from surface by 25cm.

Figure 18: Applying Offset Cut-Extrude, Up to surface


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Thereafter, the edges of the new formation needed to be blunted through the Fillet feature.

Figure 19: Blunting the edges

The extent of the fillets was assessed by measuring the straight segment of each edge of

Blade*.

Figure 20: Measuring Fillets extent


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The fillet approach was selected to blunt the edges that were formerly Offset Cut-Extruded

and generate a rounding result but Solidworks would not allow the specific intervention.

Subsequently, the sketch of the Cut-Extrude feature was altered instead. The sidelong

parallel straight lines were replaced by arcs.

Figure 21: Changing the sketch

On the longest surface of the formation, three holes needed to be designed. The path to

form the holes started with circular sketches and finished with the Cut-Extrude feature.

Figure 22: Developing the holes


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The last step of the part was the development of a cone-like component on top of the

cylindrical component and bisecting the wing of the blade. To model the specific

component, two planes parallel to the surface of the cylinder were inserted.

At first, opposite arcs were sketched on the surface of the cylinder and smaller arcs were

sketched on the parallel planes. However, the arcs were not creating a closed sketch and

thus the Loft feature was not applicable. Since the reason of the malfunction was not traced

yet, the same procedure was attempted again, trying 3D sketching, but the Loft feature

remained inapplicable. Finally, closed eclipses were sketched and this time Loft did work.

Figure 23: Lofting eclipses along planes.

Figure 24: The Blade part


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3) Creating the Impeller Assembly

The Impeller Assembly consists of two circular Hub assemblies, each of which compounds

twelve Hub parts that cluster twelve blades arrayed in a circular formation.

The first step to develop the assembly was the mating of two Hub parts as shown in Figure

25. Two sets of holes were configured to be concentric so that the parts would not move

while the opposite faces of the Hubs, namely the front face of one part and the back face of

the other part, were configured to be coincident.

The design intent of Solidworks is worth mentioning at this point. When selecting the holes

of the Hubs, the system sets as default selection the concentric mating.

Figure 25: Mating the Hubs

Mating two sets of holes and a set of faces was enough to fully define the Hub relationship.

The remaining step was the introduction of the Blade within the gap between the two Hub

parts. Once again, two sets of holes and a set of faces needed to be constrained. Concerning

the holes, it did not matter which of the two Hub parts would be selected to mate, as long as

the corresponding hole would be selected. Concerning the face, it was important to select

the correct face of the Blade to mate it with the corresponding face of one of the Hub parts.

When mating the sets of holes, a previous error emerged. The distance between the upper

hole and the bottom ones of the Hub part was miscalculated. As a result, the upper holes

between the Hubs and the Blade could not be mated post to the bottom holes mating.


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Figure 27: Applying Circular Pattern on Hubs

Figure 28: The Impeller Assembly, fully defined


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Then the circular pattern feature was selected to create similar humps alongside the face of

the cylinder. However, three instances needed to be skipped, so that the Struts could be

mated with the motor later on, as in MAICOs pattern.

At first, an effort was made not to skip those instances, but to edit them instead. Since they

were circular patterned Solidworks would not allow changes outside the pattern.

Consequently, after completing the pattern of the extrusion, in lieu of the skipped instances

a sketch was designed for the socket of the Struts. In reality, three features were applied to

form the socket. First, a sketch was drawn and an extrusion was performed, both identical to

those of the humps. Then, a second sketch was drawn on the top face of the extruded

component (Figure 30). Finally, a hole was placed in the middle of the though sketching a

circle and Cut-extruding. The component was then circular patterned to fill in the three

instances skipped by the precious Circular Pattern.

Figure 30: A socket

The following step was the blunting of the front edges of the humps through Fillet. By

editing the first hump, the one used to pattern the rest, Solidworks would not understand

that the Fillet feature should be applied to the patterned humps as well. Nor was it possible

to include the Fillet feature in the Circular Pattern command, as it was applied post the

command and the History Tree was de-activated for the features under the Circular Pattern.

Only selections over the Command were active. Therefore, the Fillet feature was dragged

between the hump extrusion and the Circular Pattern. This way, the Circular Pattern would

allow the inclusion of the Fillet feature.


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Figure 31: Editing the Circular Patter - Including Fillet

Since the Motor was to be developed as a block, the back cover ought to be designed on the

Motor. A semi-spherical component should be included on the back face of the cylinder. This

was attempted to be done through the Dome feature. Nonetheless, two issues impeded

Domes application.

At first, Dome needed a whole face to add the semi-sphere. When trying to select a sketch

drawn on the back face of the cylinder, the Dome feature declined the sketch and added theface instead. Note that the semi-sphere was not intended to cover in total the back face.

To overpass this issue, the circular sketch was Cut-extruded by an imperceptible amount of

mm, so that a new face at the dimensions of the sketch would be created for the Dome

feature.

The solution to the first issue did allow the development of the hemisphere. But the model

also needed a rectangular box that would start from the back face of the cylinder and end at

the same distance as that of the hemispheres crest, passing through the hemisphere for

some part of it.

After sketching the rectangle on the back face of the cylinder, the Extrude Boss Base

feature could not be applied as the rectangular solid would have to pass through the

Domed hemisphere, which Solidworks would not allow.

Consequently, the hemisphere needed to be developed using another Solidworks feature.

Both the Dome and the formerly applied Cut-Extrude feature, which was applied on the back

face of the cylinder, were deleted. On the right plane, a quarter of a circle was sketched and

through the Revolve Boss Base feature the hemisphere was developed again (Figure 31).

This time the rectangular solid that would pass through the hemisphere could be developed

without problems (Figure 32).


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Figure 32: Applying Revolve Boss Base

On the front face of the cylinder, a smaller cylindrical tube that would act as linking tool to

the Front Cover part needed to be developed. Thence, a circular sketch was drawn and

extruded in the middle of the front face of the cylinder. On the front face of the new,

smaller cylinder a hexagonal sketch was inserted, circumstanced by the circular shape of the

face. Within the same sketch, a second, smaller hexagon was sketched inside the first

hexagon. The edges of the two hexagons were restricted to be parallel. The sketch including

the two hexagons was then extruded.

Figure 33: Creating the Front Cover link


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The newly developed hexagonal reception needed holes in the middle of the each of its

edges. The holes were planned to act as screw receptions. This time, instead of cut-

extruding sketched circles, the Hole Wizard was utilized. The specifications for the screws

that would be mated were inserted (standard, type, size) and the positions were left to be

selected.

To select the positions, centerlines were sketched on the hexagons faces before using the

Hole Wizard. However, sketches deployed outside the Hole Wizard feature could not be

used for constraint-related reasons. Only sketches developed during the positioning process

of Hole Wizard feature were allowed to be used to set constraints and relationships (i.e.

midpoint) for the positioning of the holes. As a result, the centerlines sketched before the

Hole Wizard utilization were replaced by identical centerlines drawn in the frame of the Hole

Wizard.

Figure 34: Using the Hole Wizard

The last step of the Drive Motors development was the creation of a hemisphere on top ofthe rectangular box. The procedure followed was the same as that of the first hemisphere. A

quarter of a circle was sketched so that the Revolve Boss Base Feature could be applied. A

centerline, perpendicular to the rectangular boxs face, was also sketched to be used as line

of revolution.


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Figure 35: Developing the second hemisphere

It is worth mentioning that after the application of the Circular Pattern on the humps, the

model got too heavy for the host-computer. For instance, every time the model was

rotated, the computer was stalling, most likely due to the complexity of the model.


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5) Creating the Front Cover

The Front Cover was supposed to serve two needs in the assembly. First, it should cover the

Hubs and second, it should link the Hubs, the Blades and the Motor so that the latter wasenabled to rotate the Blades.

To begin with the first need, the dimensions of the Hub Circular Pattern was needed. By

entering the Impeller Assembly, a concentric and coincident circle to that of the Hub Circular

Pattern was sketched and estimated through Smart Dimensions.

Then, a new part file, named Front Cover, was created. The first sketch to be drawn was that

of circle in the same dimensions as the Hub Circular Pattern. Then the sketch was extruded.

Figure 36: Circles extrusion

Thereafter, the Dome feature was applied on the front face of the cylindrical shape to make

it look like a part of a sphere.


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Figure 37: Applying the Dome Feature

The Dome feature on the front face was followed by the Shell feature on the back face to

remove material, leaving a constant 1mm wall to form the part.

Figure 38: Applying the Shell feature

After the Shell feature, the initial sketch of the part was extruded again, backwards this time.

This way the spherical front face would remain spherical and cavernous while the back face

would allow further interventions for a distance equal to the extrusion distance.

The order of the features has been critical for the formation of the configuration of the part.


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Figure 39: The backwards Boss Base Extrusion

A sketch of a circle, concentric to the back face, forming an equally sided cross within it, was

Cut-Extruded by the same amount of mm as the precedent Boss Base Extrusion.

Figure 40: Cut-Extruding the cross-divided circle.

Subsequent to the back faces formation, holes were created to serve the second role of the

part; the mating capacity of the Impeller assembly with the front cover. A circle was

sketched on the back face of the part, after assessing its position by opening the Hub part


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At this point, it was noticed that the dimensions used as pattern were calculated after the

Hub* part and the .igs file. Hence, the Scale feature needed to be applied.

Afterwards, a way to link the Front Cover with the Motor needed to be implemented. That

was accomplished by constructing a tube on the back face of the part, and on top of the

latter a hexagon destined to penetrate the hexagonal slot of the Motor.

The tube was developed by sketching a circle in the middle of the back face and on top of

the cross. The circle would be then extruded to add material and create the cylinder.

On the back face of the cylinder, a hexagon was sketched (from the midpoint of the face). Its

dimensions were assessed after those of the slot and the accidence was adjusted by adding

a parallel constraint between an edge of the hexagon and an edge of the cross.

Figure 43: The part after the hexagons construction

Holes destined to be mated with those of the Motor were the last touch on the part. By

sketching an auxiliary centerline, the corresponding position of the hole on one of the

hexagons face was assessed. A circle, in the same dimensions as those of the holes of the

Motor part, was sketched and Cut-Extruded. The extrusion depth was set to be 10 cm, to

match the difference between the length of the selected screw (the slots holes were

inserted using the Hole Wizard) and that of the slots thickness.


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6) Creating the Duct Sleeve

The Duct Sleeve is destined to contour the Impeller. Thus its diameter should be larger than

that of the Impeller (in particular of the Circular Blade Pattern).

The diameter was set at 1550 mm and the depth of the contouring material at 15mm.

Two concentric circles were sketched and extruded.

Figure 46: Applying Extrude Boss Base

In the front of both the faces of the part, the Duct Sleeves sheet iron needed to be a bit

broader for a few mm. Thus a third circle, greater than the previous ones, was sketched.

The extrusion of the third circle covered the ensemble of the face. A fourth circle, identical

to the second one had to be drawn within the same sketch, so that the system could

understand and apply the required, partial extrusion (Figure 47).

To repeat the extrusion on the opposite face of the part, a new plane was inserted (Insert

Reference Geometry), detached from the Front one, which had been the first sketchs plane,

by as many mm as the first extrusion was and towards the same direction (Figure 48).

On the new plane, the last extrusions process was repeated.

Prior to inserting a new plane, the Mirror feature was attempted to be applied. A centerline

was drawn in the middle of the distance of the two faces but it turned out that Mirroring is

available only when its point of reference (the entity around which it is to be performed) is a

plane or a face. In the case above, neither of the two existed in the middle of the extrusion

distance.


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Figure 47: Applying the Extrude Boss Base feature on the second sketch

Figure 48: Inserting a new plane


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The following step was the construction of a reception for the Terminal Box, which needed

to be placed on top of the part.

To make the sketch, the 3D Sketch tool was tried out. One would believe that this particular

sketch tool would enable sketching on non-planar surfaces, but it turned out that he/she

would be wrong. The 3D sketch tool was available when selecting the curved surface as the

sketching face, though, when drawing, the sketch would be formed on the planar plane

under the surface.

Thence, the sketch was drawn on the top plane, in the middle of the part, and the extrusion

was chosen to be applied Offset by the amount of mm of the radius of the part plus 30

mm, downwards, Up to Surface.

Figure 51: Offset extruding Up To Surface and downwards

A cube was then developed, but that was not enough, since the goal was to construct a

case/reception. Thus, on the top face of the cube, a square was sketched and Cut-Extruded,

so as to generate the space that was intended to be filled by the Terminal Box when

assembling the parts.


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Figure 52: Applying Cut Extrude on the Terminal Boxs reception

To complete the reception, the positions and the type of the fasteners that would bind the

Terminal Box in the case needed to be determined.

Using the Hole Wizard, two receptions were created on the Front and the Back face of the

case. The positions of the receptions were determined using sketch entities within the Hole

Wizard.

Figure 53: Using the Hole Wizard


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To simulate MAICOs pattern, small holes needed to be developed around the front and the

back face of the part.

A circle was sketched between the edges of the sheet iron on the front face (Figure 54). The

sketch was then Cut-Extruded and Circular Patterned (Figure 55)

Figure 54: Cut-extruding the circular sketch

Figure 55: Applying the Circular Pattern Feature


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7) Creating the Terminal Box

The Terminal Box was supposed to fit in the gap of the reception on top of the Duct Sleeve.

Consequently, its surface area should be equal to the area of the Cut-Extruded squaresketched on the reception.

A new part file was opened and an identical square to the above-mentioned was sketched.

The Extrude Boss Base feature was selected to add material to the sketch and generate a

rectangular box.

Figure 57: Creating the rectangular box

The terminal box in the MAICON pattern includes buttons.

On the top face of the rectangular box, a smaller square was sketched so as to apply the Cut-

Extrude feature and place cylinders buttons in lieu of the removed material.


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Figure 58: Removing material through Cut-Extrude

Explicitly, on the top face of the Cut-Extruded Area a circle was sketched. After determining

the dimensions and the position, Extrude Boss Base was applied to the circular sketch, to

generate a cylinder-button.

Figure 59: Creating the first button


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The Linear Pattern feature was applied to the cylinder, so as to make copies throughout the

face. Through this feature, the distance between the copies, their direction and their

number needed to be determined.

Figure 60: Applying the Linear Pattern

The last step of the parts modeling was the inclusion of holes, in two opposite external

sides. Through those holes the fasteners would bind the Terminal Box with the case of the

Duct Sleeve. Thus, the radius of the new holes needed to be equal to the radius of the holes

on the case-reception, while the positions of the holes on the Terminal Box should match

the positions of the on the reception, when they would be mated.


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Figure 61: Sketching a circle to generate a hole

The holes were modeled using the Cut-Extrude feature.

At this point, it is worth mentioning that when the sketch was drawn on one of the opposite

sides and the second sketch was under drawing, the first sketch was discernible (on the

back). By selecting the center point of the opposite circle and dragging up to its

circumference, the system understood and automatically marked the new circle as fully

defined, creating a relationship between the two sketches by itself.


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8) Creating the Strut

To create the Strut part, a different modeling approach was put forward. The Strut was

supposed to bind the Motor and the Duct Sleeve. Subsequently, an Assembly was created, inwhich the two parts were inserted.

The circumferences of the front faces of the Motor and the Duct Sleeve were then mated,

setting Concentric as their relationship type.

Figure 62: Configuring the concentric mate type

Thereafter, the straight lines of the sides of the sockets were mated. The default relationship

would be coincident. The sockets were then aligned and the assembly in order.

Figure 63: Mating the sides of the sockets


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From the Front view and on the Front Plane, the Sketch tool was selected. The ouline of the

Strut could then be drawn.

At first, lines parallel to the edges of the sockets, linking the two parts, were sketched. Then,

two pairs of circles, all concentric, were sketched. Each pair would be tangent to the

opposite sides of a socket, as in the Figure below.

Figure 64: Sketching the sockets outline

By trimming the entities, the sketch of the strut would be left on the screen. Then, by

selecting Edit Copy, the sketch was copied and pasted to a new file. An extrusion was the

only required task to generate the Strut. The extrusion depth would be same as that of the

socket of the Motor.

Figure 65: Extruding the pasted sketch


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9) Creating the Screws

Prior to assembling the parts, fasteners needed to be modeled so that all parts could be

buckled.

To begin with, the most popular hole in the assembly was the one corresponding to the ANSI

Metric Hex Screw M3.

To model the corresponding screw, a new part file was opened and a sketch was designed,

aligned with the dimensions of the selected screw.

The Revolve Boss Base feature would add material to the sketch and generate the solid part.

The Chamfer feature was then applied to the top circular edge of the part.

Figure 66: Applying the Revolve Boss Base Feature


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Figure 67: Chamfering the edges

Finally, a polygon was sketched and Cut-Extruded on the top face of the part to create a

reception for the screwdriver.

Figure 68: Creating the screwdrivers reception


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Then one more type of screw was sketched after the dimensions of the bigger holes of the

Impeller Assembly, which did not belong to a standard due to the random Scale Factor.

To create the new screws, the dimensions of the first screw were modified and the resulting

files were saved with different names. The length of the screws was subject to the overall

depth of the parts they would drive through.

Figure 69: Editing the first sketch of the screw to modify the dimensions

Figure 70: Cut-Extruding the new modified polygon


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Afterwards, a third type of screw was developed, accompanied by a nut destined to the

smaller holes of the Impeller. This time, the Helix/Spiral feature was used to mate the Screw

with the Nut.

At first, a hexagonal sketch entity was inserted and extruded.

Figure 71: Extruding the polygon

On the back face of the polygon a circle was sketched and extruded.

Figure 72: Extruding the circle on the back face


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Then, a second concentric circle was sketched, matching the diameter of the small holes of

the Impeller. The circle was then extruded by a depth equal to the depth of the holes plus

the depth of the Nut that would be created later on.

Figure 73: Creating the cylinder

The edge of the resulting cylinder was chamfered.


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Figure 74: Chamfering the edge-circumference of the cylinder

The Helix-Spiral feature was then selected and a circle equal and concentric to that of the

cylinder was sketched on the back face of the part.

Figure 75: Applying the Helix/Spiral feature


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The Helix-Spiral feature options opened and the definition of the feature by height and pitch

was selected, with a pitch size of 1.35mm and a height equal to the extrusion depth of the

Nut that was to be constructed.

Then a triangle was inserted on the right plane. The center point of the polygon was set to

be coincident to the extension of the circumference of the cylinder, as shown in the Figure

below.

Figure 76: Inserting the shape of the Cut

Then, the Cut-Sweep feature was applied selecting the triangular sketch as profile and the

Helix/Spiral feature as path.

Figure 77: Applying the Cut-Sweep feature


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Finally, a circle was sketched on the front face of the part and the Cut Extrude feature was

applied, flipping the side to cut and inputting a draft of 60.

Figure 78: Cut-Extruding the vertices of the part

After completing the Screw, its corresponding Nut needed to be designed. The same

hexagon as that of the Screw was designed, adding a circle within the same sketch equal to

the circle that formed the cylinder of the Screw. Then the Extrude Boss Base feature was

applied.

Figure 79: Extruding the outline of the Nut


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Post to the extrusion, the Helix-Spiral feature was selected and an equal and concentric

circle to that of the resulting hole was sketched on the back face of the part. A triangle equal

to that of the Screw was then designed and set as coincident to the ending of the hole, as

shown in the Figure below.

Figure 80: Inserting the Cut shape

Thereafter, the Cut Sweep feature was applied selecting the Helix Spiral feature and the

triangle.

Figure 81: Applying the Cut-Sweep feature


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Finally, the Cut-Extrude feature was applied to both the Front and the Back face of the part

using the same configurations as in the Screws Cut-Extrusion.

Figure 82: Cut-Extruding the vertices


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Figure 84: Setting the Coincident constraint

Then, the first screw was added to the assemblage. Having selected Concentric as mating

type between the circumference of the screw and that of the large hole, the first

relationship was applied. Then a second relationship, Coincident, was added between the

faces that were to be abutted. The screw was now in the required position.

Figure 85: Setting the coincidental relationship


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The Feature Driven Pattern was tried out by selecting the screw and the Circular Pattern

applied to the Hubs, but the system would not temporarily allow it. Namely, the Circular

Pattern could not be inserted in the Driving Feature tab post to the insertion of the Screw as

patterned component. Later on, the Circular Pattern was selected as the Driving Feature

prior to the Screw selection as patterned component. The second order of selections could

be applied and screws were inserted in all the intended holes.

Figure 86: Applying the Feature Driven Pattern

Afterwards, screws were added to the smaller holes of the Impeller Assemblage. Those

screws would not bind the Impeller with another component. Their goal was to boil down

the parts of the Impeller.

For this particular bondage the spiral screws were selected for one side of the Impeller and

the nuts for the opposite side.

To apply the mate screws were restricted to be concentric to the holes and while the faces

that were to be abutted were restricted to be coincident.

Two screws were inserted and in each Hub part. On the opposite side of the Impeller, the

nuts were positioned using the same relations as those of the screws.

Having inserted a couple a Screws and a couple of Nuts, the Circular Pattern was applied to

fill in the remaining holes.


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Figure 87: Inserting the Coincident restriction

Figure 88: Inserting the Concentric restriction

To insert the Nuts, the Front Cover part needed to be hidden, by right clicking on the part

and selecting Hide. The Front Cover was covering the holes of the front side of the Impeller.


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After the first assemblage, the part Drive Motor was inserted. Two pairs of vertices of the

Motor and the Front Covers hexagons were constrained to be coincident as shown below.

Figure 89: Mating the Front Cover with the Drive Motor

Then, a screw corresponding to the holes of the hitch was inserted. The mating relationships

were once again Concentric and Coincident and the Circular Pattern feature filled in the

remaining five holes.

The following Parts that needed to be inserted were the Strut and the Duct Sleeve. The Strut

had to be mated with both the Drive motor and the Duct Sleeve. In fact, it was supposed to

bridge the gap between the two parts. When modeling the Strut, the holes for the reception

of screws that would joint together the Struts and the sockets were not developed as the

Hole Wizard is applicable within Assemblies as well.

At first, the circumferences of the Drive Motor and the Duct Sleeve were set to beconcentric, to position the parts.


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Figure 90: The Drive Motor concentric to the Duct Sleeve

However, by restricting the two parts to be concentric, the Drive Motor would no longer be

able to move across the Duct Sleeve. The Motor needed to be positioned in the middle of

the Duct Sleeves depth but the concentric constraint would allow the backwards motion of

the first, although, if allowed the parts would virtually remain concentric.

Then the Strut was inserted, but its reception for the socket of the Duct Sleeve could not be

restricted to the required spot within the Duct Sleeve, because the socket of the latter was

continuous throughout the part. It did not have any vertices or other characteristics to mate

them with the Strut.

Thence, the Duct Sleeve part was opened and holes were developed in the required

positions, in the middle of the extruded area, onto the sockets.

After regenerating the assembly to update the models, holes equal to those of the Duct

Sleeve and the Motors sockets were developed via the Hole Wizard feature.

The mate would still be impossible, because the holes sketched outside the Assembly had a

different accidence from the holes sketched within the Assembly, despite the fact that the

sketches of the holes and, subsequently, their drilling points were aligned.

As a result, all the holes were deleted (on the sockets of both parts and on the Strut) and

after mating the vertices of the Struts reception with those of a socket of the Motor, the

Hole Wizard was selected again to generate a collinear hole along the mated components,

as shown in Figure 91.


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Figure 91: Creating a hole through the Hole Wizard

The Strut was still unable to be mated with a point in the middle of the Duct Sleeve since the

holes were removed. To solve this issue, the Duct Sleeve Part was opened and the

continuous extrusion of the socket was interrupted at one point, by breaking the previous

extrusion into two, having an imperceptible distance between its other. That was

accomplished by cutting in half the former extrusion depth and by sketching on the oppositeface an identical socket outline which was extruded up until 1mm from the end point of the

opposite extrusion.

Figure 92: Inserting the depth of the opposite extrusion


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The second extrusion was then added to the Circular Pattern of the first extrusion, the part

was saved and the assembly was regenerated.

As a consequence of the interruption of the extrusion of the sockets, the Struts second

reception could be mated with a socket of the Duct Sleeve, in the middle of the part, where

the 1mm interruption begot vertices that were set to be coincident to the vertices of the

reception .Holes were added again, similarly to those on the conjunction of the Drive Motor

and the Strut, and screws were added and mated with the Holes, using the same

relationships as in the mating process of the other parts.

Figure 93: The mates of the Strut part

A Circular Pattern was then introduced, compounding the Strut, the Holes and the Screws

and the assembly was fully defined.

Figure 94: Introducing the Circular Pattern


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The remaining part that needed to be inserted and mated was the Terminal Box. Its vertices

were mated with the vertices in the reception on top of the Duct Sleeve. Then the screws

corresponding to the holes were introduced and mated under the same process as the rest

of the screws and the Assembly was ready and fully defined.

Figure 95: Mating the Terminal Box with its reception

Figure 96: The fully defined Assembly

It is worth mentioning that the modifications of the parts within the assembly did not pass

to the files they stemmed from. Nor did Solidworks pose a question to regenerate the parts.


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11)Creating the Blades Drawing

After configuring the Documents Properties and the Sheet Format, the most important

views of the part Blade were inserted. From the Design Library, the part was dragged intothe sheet and the views were selected.

Creating an Auxiliary view was indispensable as the Blades head was leaning. On each of

the parts view, the dimensions were inserted using the Smart Dimensions tool. By letting

the program calculate the dimensions by itself, it would disclose those prior to the Scale

feature.

A detailed view was also required because the number of the dimensions that needed to be

illustrated was important.

The parts Drawing is presented in the following page.

Solidworks allows the inclusion of various tables within a drawing, such as a Bill of Material

in Assemblies or a Revision Table when changes occur (which do not in this case).


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PART II

1) Review of FeaturesSolidworks is a program equipped with a vast amount of features.

A recording of the features utilized in this paper, as well as their characteristics, is presented

below:

Extruded Boss/Base: Adds material to a sketch towards one or two (through the Thin

choice) directions. The draft choice may enable linear accidence in the materials addition. It

can not generate concave additions.

Extruded Cut: Removes material from a sketch. It is the opposite of the Extruded Boss/Base

feature. It shares the same limitations.

Revolved Boss Base: Adds material in a revolving course around a predefined entity.

Revolved Cut: Removes material in a revolving course.

Swept Boss/Base: Sweeps a closed sketch entity around a predefined course, such as a

spiral, adding or removing material.

Lofted Boss/Base: Adds material from a closed sketch entity up to one or more profiles.

Contrary to Extruded Boss/Base, it can generate complex concave faces.

Fillet: Rounds the intersection of surfaces, after a predetermined radius

Chamfer: Replaces the abrupt intersection corner of two faces with a third intermediate

face which, in turn, generates two intersections that share the accidence the first.

Shell: Removes material from the inside of a solid body, leaving a thin, balanced surface -

outline instead.

Draft: Adds accidence to the course - direction of a face/edge. This feature can be both

stand alone or be part of another feature, such as Revolve Boss/Base.

Hole Wizard: Enables the direct insertion of a hole in a body. Some patterns are

predetermined and available, while the possibility to model and add a new pattern isguesstimated.

Linear Pattern: Enables the automated linear recurrence of a feature within a part or even

of a part within an assembly.

Circular Pattern: Enables the automated circular recurrence of both features and parts.

Scale: Multiplies the ensemble of a part/assembly, including positions and dimensions, by a

specific factor. As a result the solid subject shrinks or expands uniformly.


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Dome: Adds material from a face up (or down) to a predefined distance in a

spherical/concave course. However, its application field may not be compounded with the

application of another feature.

Reference Geometry: Helpful reference tools (points, axis, planes, origins) may be inserted

to help delimit or define a particular feature or component of a part. The placement of those

tools may be accomplished using faces, existing planes, lines, points or even curves.

Helix/Spiral: Using a sketch entity (namely a circle), the Helix/Spiral feature develops the

course of a spiral. This feature does not actually add material by itself. It needs to be

combined with the Swept Boss/Base feature and its sketch entity.

Curve through XYZ Points: Points on the XYZ axis may be inserted in a table which will

generate a Curve after the points.

2) Constraints in parts, assemblies and Design IntentConstraints may be very helpful during the modeling process of a part/assembly. Being a

parametric modeler, Solidworks allows the inclusions of a number of constraints which may

protect the operator from errors, discharge him from having to insert a number of

dimensions, or even maintain some characteristics of the model when changes are applied

and the model is regenerated.

For instance, by restricting a line to be equal to another line, the length will need to be

determined for only one of them. In addition, if the length of one line gets modified forsome reason, its constrained to be equal line will be automatically regenerated as well.

What constraints add to a model is, in fact, the chance to lock specific relations and offer

security. In engineering, a tiny aberration may lead to the total disablement of a lot. The

automotive industry has been behind the evolution of CAD/CAM systems from the

beginnings of computerization, due to the importance attributed to accuracy.

In the example of the Axial Fan, there was a miss between the holes of the Duct Sleeve and

those of the Struts because accidence was not taken into account. The concentric constraint

could not be added and the holes needed to be regenerated. Had some sort of concentric

constraint been applied when the parts were developed it would not be necessary to arrive

to the mating stage and detect the problem.

Constraints are not delimited to the modeling of a part. They are also critical for the mating

process of an assembly. Positioning a part where it should be in comparison with another

part is not enough in Solidworks. For instance, placing a screw within its corresponding hole

would not signify a fully defined mate. Relationships need to be included, since an

imperceptible miss may provoke a series of problems. A screw has to be concentric to its

hole, while the bottom face of its head has to be coincident to the surface from which the

cut originates. Setting constraints in mates is not only vital for security and accuracy reasons

(see under Figure 25) but also for practical reasons. Instead of dragging a part to position it


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to the corresponding place compared to another part, constraints may be added directly and

result to the positioning. Solidworks labels a mate as fully defined when the parts can no

longer be dispatched.

The following table demonstrates Solidworks constraint options in both mates and

sketches.

Constraint Type Sketches Mates

Coincident

Concentric

Fix x

Pierce x

Midpoint x

Tangent

Perpendicular/Vertical

Horizontal x

Parallel

Distance Through smart dimensions

Angle Through smart dimensions

Patterns Both in sketches and in features Including feature driven

Mirroring Both in sketches and in features

Aligned/Antialligned x

Table 1: Solidworks constraint types

During the development of the Axial Fan Assembly it had been noticed that constraints were

often added by the system itself. When sketching a line from a point close to another line,the system added the Coincident constraint arbitrarily. Furthermore, when a circle was

sketched from the midpoint of another circular surface, the system added the Concentric

constraint and when a rather perpendicular line was sketched from another line the

Perpendicular constraint was automatically included. The ability of Solidworks to predict the

operators will is called Design Intent.

Moreover, the ability of the system to allow or even present (in sketches) only possible

constraints may also be included in its intelligent comportment. Under Figure 61, an

example of Solidworks Design Intent is provided.

Solidworks is a very convenient, user-friendly CAD system and its dominance in the global

market is rather rational.