unigraphics nx associative parametric design mt10040 workbook

Associative Parametric Design

WorkbookMay 25, 2007

MT10040 — NX 5

Publication Numbermt10040_w NX 5

Manual History

ManualRevision

Versions PublicationDate

NX 5 May 2007

Proprietary and restricted rights notice

This software and related documentation are proprietary to UGS Corp.

Copyright 2007 UGS Corp. All Rights Reserved.

All trademarks belong to their respective holders.

2 Associative Parametric Design – Workbook mt10040_w NX 5

Contents

The Vacuum Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Cloning an Existing Pump Assembly . . . . . . . . . . . . . . . . . . . . . . . . 1-1

Adding Mounting Lugs to the Crankcase . . . . . . . . . . . . . . . . . . . . . 2-1

Creating the Pump Cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

Creating an Expression to Suppress the Lugs . . . . . . . . . . . . . . . . . 4-1

Adding a Lift Ring Boss to the Crankcase . . . . . . . . . . . . . . . . . . . . 5-1

Adding Blends to the Crankcase and Cover . . . . . . . . . . . . . . . . . . . 6-1

Simplifying the Crankcase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1

Adding Components to the Assembly . . . . . . . . . . . . . . . . . . . . . . . . 8-1

Positioning the Lift Ring at the Center of Mass . . . . . . . . . . . . . . . . 9-1

Determining the Pump Performance . . . . . . . . . . . . . . . . . . . . . . . 10-1

Determining the Pulley Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-1

©UGS Corp., All Rights Reserved Associative Parametric Design – Workbook 3

The Vacuum Pump

The vacuum pump assembly used in this class is a "seed" assembly driven bykey parameters that will be modified and optimized for desired performancecharacteristics. The design of this assembly should be considered in progress.It is intended to be used as a starting point for future detailed designs.

The goal of this project is not to complete a fully-detailed assembly but to gainan understanding of the functionality covered in this class in the context ofthe overall design process.

Below is an illustration of the assembly that you will be working with duringthe class. The pump is designed to displace air for degassification and dryingchamber applications. The air is displaced by a piston which is connected toa crankshaft and pulley system. The pulley is driven by a motor and beltwhich will not be part of the assembly.

1 Head 6 Piston

2 Cylinder 7 Crankshaft3 Lift ring 8 Cover4 Crank Case 9 Pulley5 Connecting Rod

©UGS Corp., All Rights Reserved Associative Parametric Design – Workbook 5

The image below represents the Modeling Spreadsheet in its final state.

6 Associative Parametric Design – Workbook ©UGS Corp., All Rights Reserved mt10040_w NX 5

1Lesson

1 Cloning an Existing PumpAssembly

As a starting point, you will clone an existing, incomplete pump assemblycontaining a few of the structural components. You will also clone asubassembly and the other piece parts that will later be added to your pumpassembly. The assemblies you clone contain existing interpart links andmating conditions that will be maintained in the cloned parts.

Step 1: Clone the pump assembly and the other parts required for theproject.

Clone the following assemblies and piece parts from the projectfolder.

Assemblies: apd_pump_assm, apd_rod_subassmPiece Parts: apd_crankshaft, apd_lift_ring, apd_piston,apd_pulley, apd_pulley_nutThe Add Assembly or Add Part option can be chosen for each ofthe parts to include all of them in the same cloning operation.

Note

The piece parts are not currently part of any of theassemblies. They will be added to the assembly later.

Define a Naming Rule to replace the string apd with *** for allparts (where *** are your initials).

©UGS Corp., All Rights Reserved Associative Parametric Design – Workbook 1-1

1

Cloning an Existing Pump Assembly

Use your home directory as the Default Output Directory.

Step 2: Open a few of the cloned parts and verify that the cloning operationwas successful.

***_pump_assm

***_rod_subassm

***_crankshaft

***_pulley

***_lift_ring***_pulley_nut

***_piston

Note

The crankcase will be completed and a cover will be createdin later sections.

Step 3: Close all parts.

1-2 Associative Parametric Design – Workbook ©UGS Corp., All Rights Reserved mt10040_w NX 5

2

Lesson

2 Adding Mounting Lugs tothe Crankcase

The pump assembly will have optional lugs that will allow it to be mountedon its end. So that these mounting lugs can be easily identified and excludedfrom the model (suppressed), they will be grouped together in feature sets.


2

Adding Mounting Lugs to the Crankcase

Step 1: Open ***_pump_crankcase.

Step 2: Identify the features that compose the existing lug.

Step 3: Group the features that compose the LUG into a feature set.

Create a feature set named LUG consisting of the identifiedfeatures and hide the members. You do not have to include thesketch defining the lug profile in the feature set.


2

Adding Mounting Lugs to the Crankcase

Step 4: Create a circular feature Instance Array of the LUG feature set.

Create an array of 4 lugs spaced 90 degrees apart.

Use the datum axis on layer 21 as the rotation axis for thearray (parallel to the absolute X axis).

Step 5: Save and close the part.


3

Lesson

3 Creating the Pump Cover

The design intent for the cover of the pump is:

• The flange matches the mating flange in the crankcase.

• The profile is parametrically controlled and related to the profile of thecrankcase.

Step 1: Open ***_pump_assm.

Step 2: Create a new empty component part named ***_pump_cover.

In the Create new Component dialog box, from the Units list,choose Inches choose Inches, and select the Model Template.

In the New File Name group, enter ***_pump_cover in theName field.

In the New File Name group, browse to the Folder thatcontains the parts you cloned for this project.


3

Creating the Pump Cover

Click OK.

Step 3: Change the work part to ***_pump_cover.

Step 4: Use the Wave Geometry Linker to link the sketch of the profile ofthe crankcase and reference datums into the new cover part.

Make layer 21 selectable and replace the BODY reference setin ***_pump_crankcase with the SKETCH reference set.

Using the Wave Geometry Linker, link the datum plane, anddatum axis into the ***_pump_cover part.

Using the WAVE Geometry Linker, link the sketch into the***_pump_cover part.

Note

You will need to set the Curve Rule list (in the SelectionBar) to Feature Curves to select the entire sketch.

1. Datum Axis

2. Datum Plane

3. Sketch


3


Step 5: Change the displayed part to ***_pump_cover.

Step 6: Create a sketch for the main profile of the cover.

Create a sketch named main_profile on the linked datum planeusing the linked datum axis as the horizontal reference.

Note

Keep layer standards in mind when creating the sketch.

Sketch the curves and apply constraints as shown below.

Apply Collinear geometric constraints to relate the sketchcurves to the curves in the linked sketch. (Not all geometricconstraints are shown; additional Collinear, Horizontal, andVertical, and Parallel constraints will be required.)

Step 7: Revolve the main profile sketch about the datum axis 360 degrees.


3


Step 8: Change the displayed part to ***_pump_assm and the work partto ***_pump_cover.

Step 9: Use the Wave Geometry Linker again to link the face on the flangeof the crankcase.

Replace the SKETCH reference set in ***_pump_crankcasewith the BODY reference set.

Using the Wave Geometry Linker, link the planar face of theflange in the crankcase into ***_pump_cover.

Step 10: Change the displayed part to ***_pump_cover.

Step 11: Extrude the linked face.

Extrude the linked face using a Start Distance of 0 and an EndDistance of 0.25.

Unite the extruded feature with the revolved solid.


3


Step 12: Create a sketch for a web profile.

Create a sketch named web_profile on the linked datum planeusing the linked datum axis as the horizontal reference.

Sketch the curves and apply constraints as shown below.

Apply Collinear geometric constraints to relate the sketchcurves to the curves in the main profile sketch.

Step 13: Extrude the web profile sketch.

Create the expression, web_thk=.375.

Extrude the web profile using the following parameters:

Start Distance=–web_thk/2 End Distance =web_thk/2

Unite the extruded feature with the revolved solid.

Step 14: Rename the extruded feature to WEB.


3


Step 15: Create a circular feature instance array of the web.

Create an array of 4 webs spaced 90 degrees apart.

Use the linked datum axis as the rotation axis for the array.

Step 16: Change the displayed part and work part to ***_pump_assm.

Step 17: Replace the reference set for ***_pump_cover to MODEL.


4

Lesson

4 Creating an Expression toSuppress the Lugs

The pump assembly has lugs that will allow it to be mounted on its end. Sothat these lugs can be excluded in certain configurations of the assembly froma spreadsheet, an expression will be created to control their suppression.


4

Creating an Expression to Suppress the Lugs

Step 1: If necessary, open ***_pump_crankcase, and if necessary. make itthe Displayed Part..

Step 2: Create an expression to suppress the mounting lugs.

Create a single expression to suppress all of the instances ofthe LUG feature set and the associated circular array.

Rename the expression to show_lugs.

Step 3: Test the expression.

Change the value of the show_lugs expression to suppressthe lugs and update the model.

Change the value of the show_lugs expression to unsuppressthe lugs and update the model.



5

Lesson

5 Adding a Lift Ring Boss tothe Crankcase

The design intent requires that a lift ring be attached to the crankcase andlocated near the center of mass of the assembly. A boss is required on thecrankcase for attaching the lift ring. To allow flexibility for future designchanges, a sketch will be used to define the shape of the boss.


5

Adding a Lift Ring Boss to the Crankcase


Step 2: Create expressions for the location of the lift ring boss.

Create the following expressions:

xlift=3.5 ylift=–2.25

Step 3: Create datum planes to define the top face of the lift ring boss.

Create a datum plane parallel to the fixed datum plane onlayer 21 (in the absolute XY plane) and tangent to the outercylindrical face of the case (1).

Create another datum plane offset 0.375 inches above thetangent datum plane (2).


5


Step 4: Create a sketch to define the top outline of the lift ring boss.

Create a sketch on the offset datum plane namedBOSS_OUTLINE, using the offset datum plane (1) as theplacement face and the datum axis (2) on layer 21 as thehorizontal reference (along absolute X axis).

Create a single circle in the sketch and constrain it as shownbelow.

Note

Since dimensional constraints cannot be negative, theabsolute value function, absf/(/), must be used to convertthe value of the expression ylift to a positive value.


5


Step 5: Extrude the sketch to create the boss.

Extrude the sketch downward, trimming it to the outercylindrical face of the crankcase. Use a taper angle of 5 degreesand unite the extruded feature with the solid.

Step 6: Create a hole on the top of the boss.

Create a simple blind hole centered on the top of the boss withthe following parameters.

Diameter=0.625 Depth=0.75 Tip Angle=118

Step 7: Group the features that compose the lift boss in a feature set.

Create a feature set named LIFT_BOSS consisting of theextruded feature and the hole.

Step 8: Create an expression to suppress the lift boss.

Create an expression to suppress the LIFT_BOSS feature setand rename the expression to show_lift.



6

Lesson

6 Adding Blends to the Crankcaseand Cover

In this section of the activity, you will add blends to complete the designof the crankcase and cover.


6

Adding Blends to the Crankcase and Cover

Step 1: Create blends on the crankcase.

Open ***_pump_crankcase.

Create a 0.5 inch Edge Blend at the base of the lift ring boss.

Create a 0.5 inch Face Blend between the flange and the sideof the cylinder as shown.

Create a 0.31 inch Edge Blend around the base of the flangeand cylinder.

Step 2: Add the blend at the base of the lift ring boss to the LIFT_BOSSfeature set.


6


Step 3: Create blends on the cover.

Open***_pump_cover.

Create Edge Blends on the webs as shown below. All instancesof the web should be blended the same.

Create edge blends shown below.


6


Create Edge Blends on the outside of the cover.

Step 4: Save and close all parts.


7

Lesson

7 Simplifying the Crankcase

When the pump is eventually added to higher level assemblies, it may benecessary to display an accurate envelope while hiding internal detail toimprove system performance. In this section, you will extract and simplifythe detailed solid body of the crankcase.


7

Simplifying the Crankcase


Step 2: Extract the solid body.

Extract the solid body on layer 2.

Note

An extracted solid is used for the simplification so thatthe original detailed solid will remain intact.

Step 3: Simplify the extracted solid body.

Simplify the extracted solid body to remove the internal facesand the smaller holes on the flange and mounting faces.

Step 4: Create a reference set for the simplified solid.

Create a reference set named SIMPLE_BODY and add thesimplified solid body to it.

Note

Separate reference sets are created so that both solids donot have to be loaded when the assembly is opened.

Step 5: Remove the extracted body from the Model("BODY") reference set.

Note

The Model ("BODY") reference set is an automated referenceset. It is generated when the first sheet body or solid bodyis created. If additional solid bodies are created, they areautomatically added to the reference set.



8

Lesson

8 Adding Components to theAssembly

In this section, you will add all remaining components to the assembly andapply mating conditions to meet the design intent.

• The crankcase is the base component. The positions of all the othercomponents depend on its position.

• The cylinder, head, and cover components have already been added to theassembly but have no mating conditions applied to them. Their positionsare defined by the linked geometry from the crankcase that was used toconstruct them.

• The crankshaft, connecting rod, piston, and fasteners are partiallyconstrained and are free to rotate about an axis.


8

Adding Components to the Assembly


Step 2: Hide the cover, cylinder, head, and bolt components.

Note

This will make it easier to select faces on the crankcasewhen mating the crankshaft.

Step 3: Add the crankshaft to the assembly.

Add the part ***_crankshaft to the assembly using the followingsettings

Ref Set:Model Positioning:Mate Layer options:Original

Apply a Center (1 to 1) main constraint to align the crankshaftwith the crankcase.

Note

Position the crankshaft away from the crankcase. It willbe constrained further after the piston is added andaligned with the crankcase.


8


Step 4: Add the connecting rod subassembly and mate to the crankshaft.

Add the part ***_rod_subassm to the assembly using theModel reference set, Mate, and Original layers options.

Apply Center (1 to 1) and Center (2 to 2) constraints to positionthe subassembly with the crankshaft as shown.

Note

The rod subassembly will not be fully constrained. UseReposition to rotate it into the approximate positionshown above.


8


Step 5: Add the piston and mate it to the connecting rod subassembly.

Add the part ***_piston to the assembly using the Modelreference set, Mate, and Original layers options.

Apply Center (1 to 1) and Center (2 to 2) constraints to positionthe piston with the piston pin as shown.

Apply a Center (1 to 1) constraint to align the piston with thecrankcase.


8


Step 6: Show all components.

Step 7: Add and mate the pulley.

Add the part ***_pulley to the assembly using the Modelreference set, Mate, and Original layers options.

Apply Mate, Center (1 to 1), and Parallel constraints to positionthe pulley relative to the crankshaft.


8


Step 8: Add and mate the pulley nut.

Add the part ***_pulley_nut to the assembly using the Modelreference set, Mate, and Original layers options.

Apply Mate and Center (1 to 1) constraints to position thepulley nut as shown.

Step 9: Add and mate the lift ring.

Add the part ***_lift_ring to the assembly using the Originallayer option.

Apply Mate and Center (1 to 1) constraints to position the liftring on the crankcase as shown.

Note

The lift ring does not have to be fully constrained. UseReposition, if necessary, to rotate it into the approximateposition shown above.



9

Lesson

9 Positioning the Lift Ring atthe Center of Mass

In this section, you will use the modeling spreadsheet to calculate the centerof mass of the assembly. The coordinates of the center of mass will beassigned to interpart expressions and referenced by the crankcase componentto position the boss for the lift ring.


9

Positioning the Lift Ring at the Center of Mass


Step 2: Create the interpart expressions for the x and y coordinates ofthe center of mass.

Create the following expressions in ***_pump_assm:

IPE_xlift=3

IPE_ylift=-2

These are initial approximate values for the coordinates. Theywill change when the actual center of gravity is calculated inthe spreadsheet.

Note

The "IPE" prefix is used in the expression name so thatthey can easily be identified as interpart expressions.

Step 3: Edit the expressions defining the lift ring boss location in thecrankcase to reference the expressions in the assembly.

Change the Work Part to ***_pump_crankcase.

Edit the xlift and ylift expressions to link them to theexpressions in the assembly.

xlift=***_pump_assm::IPE_xliftylift=***_pump_assm::IPE_ylift

Step 4: Change the work part back to ***_pump_assm and make sure theWCS is set to the Absolute Coordinate System.

Note

The MASS3D spreadsheet function returns coordinate valuesrelative to the WCS. The dimensional sketch constraintslocating the lift boss are measured from datums along theabsolute coordinate system axes.


9


Step 5: Create a spreadsheet in the assembly to calculate the center ofmass and update the expressions.

Invoke the Modeling Spreadsheet and extract the expressionsin a vertical orientation.

Use the MASS3D function to calculate the center of mass ofall SOLIDS and return the results in inches.

Note

In Excel, when applying a function in which the outputproduces multiple fields, you must first select all of thecells that the function will fill, type in the function, andthen hit Ctrl-Shift-Enter.

Note

Your results will probably differ from those shown in thefigure below in row eight, depending on the position ofthe crankshaft. To obtain an "average" center of mass,the crankshaft and piston may be repositioned to amid-stroke position.

A B C123 Parameters4 IPE_xlift =35 IPE_ylift =-26

7 Center ofMass

8 XC YC ZC9 4.0139353 -2.2126157 0.1455048710

Set the expression values equal to the appropriate cell for thecenter of mass coordinate. (In the example above IPE_xlift =A9 and IPE_ylift = B9.)


9


Step 6: Update the NX part.

Note

The center of mass used for the update was based on theoriginal location of the lift ring. The update then returnsnew values for the center of mass. To obtain a more accurateresult, you could perform another update, or, suppress theLIFT_BOSS feature set and ***_LIFT_RING componentbefore updating.

Note

A density may be assigned to a solid by choosingEdit→Feature→Solid Density or by assigning a materialusing Tools→Material Properties. The component partcontaining the solid must be the work part.



10

Lesson

10 Determining the PumpPerformance

The performance of the pump is rated on the volume of air that it can displacein cubic feet per minute. The key parameters that determine the displacedvolume are the piston diameter, the throw distance of the crankshaft, andthe speed of the crankshaft. In this section you will modify the spreadsheetto control these key parameters, calculate the performance rating for apump configuration, and update the assembly using the Root Part CascadeUpdate method. You will also use the spreadsheet Goal Seek to determine acrankshaft speed to achieve a desired performance.


10

Determining the Pump Performance

Determining the Pump Rating Formula

The volume of air displaced by the pump during one revolution of thecrankshaft depends on the cross sectional area of the piston and the distancethe piston travels. This can be expressed in terms of the diameter of thepiston and the throw distance of the crankshaft.

The volume of air displaced per minute depends on the speed of the pulleyand crankshaft, usually given in revolutions per minute (rpm).

If the variables are provided in inch units, the units of the rating would bein cubic inches per minute. To return the results in cubic feet per minute,divide by 144.

Note

In the Excel spreadsheet the formula would be = PI/(/)*/(/(piston_dia/2/)^2/)*/(2*throw/)*rpm/144

Since the motor is not part of the assembly, the performance rating is drivenby two key geometric parameters; the piston diameter and the crankshaftthrow distance.


10


Key Parameters and the Assembly Range

The piston diameter and throw distance are the key parameters required todetermine the rating formula. Use the following expression names for theseparameters in the spreadsheet.

RPC_piston_dia RPC_throw

Note

To use the Root Part Cascade Update method, the expressions have tobe named consistently in those component parts that are to be updated.The "RPC" prefix is not required but will make it easier to identifythese critical expressions and ensure that they are unique.

The following parts are related to the piston diameter or throw distance andwill be updated from the spreadsheet with the Root Part Cascade method.

***_pump_crankcase ***_pump_cylinder ***_crankshaft ***_conrod***_piston

Note

The pulley and fasteners are not dependent on the piston diameter andthrow distance. The cover and head will update implicitly because theywere constructed with interpart links from the crankcase. They willupdate when the crankcase changes and do not have to be explicitlyupdated from the spreadsheet.


10


Step 1: Edit expressions in the crankcase.

The crankcase already contains expressions for the piston diameterand throw distance that were used to design it but they are notnamed correctly.

Open the part ***_pump_assm.

Change the work part to ***_pump_crankcase.

Rename the expression pdia to RPC_piston_dia.

Rename the expression throw to RPC_throw.

Step 2: Edit expressions in the cylinder.

The diameter of the cylinder is defined by a linked face from thecrankcase but the length still needs to be changed to vary withthe throw distance.

Change the work part to ***_pump_cylinder.

Create the expression RPC_throw=2.

Edit the expression length= 2*RPC_throw+2.5.

Step 3: Edit expressions in the connecting rod.

The length for the connecting rod should vary with the throwdistance.

Change the work part to ***_conrod.

Create the expression RPC_throw=2.

Edit the expression length= 2*RPC_throw+3.5.


10


Step 4: Edit expressions in the crankshaft.

The crankshaft contains an expression for the throw distance butit needs to be renamed.

Change the work part to ***_crankshaft.

Rename the expression throw to RPC_throw.

Step 5: The piston contains an expression for its diameter but it needsto be renamed.

Edit expressions in the piston.

Change the work part to ***_piston.

Rename the expression dia to RPC_piston_dia.


10


Step 6: Setup the spreadsheet in the assembly for a Root Part CascadeUpdate.

Change the work part to ***_pump_assm and invoke theModeling Spreadsheet.

Move the data in the cells defining the lift ring coordinates andcenter of mass down to row 20 to get it out of the way.

Enter the key parameters in the spreadsheet and thecomponent parts to update as shown.

A B1 Key Parameters Values2 rpc_piston_dia 3.253 rpc_throw 2.254567 Update Components8 jble_pump_crankcase.prt9 jbl_cylinder.prt10 jbl_crankshaft.prt11 jbl_conrod.prt12 jbl_piston.prt

Define the Expression Range with the two key parametersand values.

Define the Assembly Range with the five component parts.

Change the Update Method to Root Part Cascade Update.

Update the parts.


10


Step 7: Calculate the pump performance.

Enter a parameter for shaft_rpm with a value of 400. (Thisparameter does not have to be included in the expression rangesince it is non-geometric and only used within the spreadsheet.)

Enter the formula for the Performance Rating as defined ,substituting the variable names with the cell locations of theparameter values.

For Excel use =P()*((B2/2)^2)*(2*B3)*B4/144

For Xess use=@PI*((B2/2)**2)*(2*B3)*B4/144

A B1 Key Parameters Values2 rpc_piston_dia 3.253 rpc_throw 2.254 shaft_rpm 4005 Performance Rating 103.6971


10


Step 8: Determine the speed required to reach a desired performancerating.

Perform a Goal Analysis to determine the approximateshaft_rpm required to achieve a performance rating of 150.Vary the shaft_rpm from 400 to 1000 in 5 steps, placing theresults out of the way in column D or E. Toggle Perform UGUpdate to off since the rating can be determined from thenumerical values and is not dependent on the model itself.

D EAnalysisResults

400 103.6971520 134.8062640 165.9154760 197.0245880 228.1336

1000 259.2428

Perform a Goal Seek (Regula Falsi) to determine the correctshaft_rpm. Use upper and lower brackets of 520 and 640, atolerance of 0.1, and a maximum of 20 iterations.

A B1 Key Parameters Values2 rpc_piston_dia 3.253 rpc_throw 2.254 shaft_rpm 578.60835 Performance Rating 150

Step 9: Update the lift ring location.

The changes to the piston diameter and throw distance changethe center of mass but the location of the lift ring still needs tobe updated.

Define the Expression Range with xlift and ylift parametersand values, change the Update Method back to Work PartUpdate Only, and update the part.


11Lesson

11 Determining the Pulley Size

In the previous section, you determined a crankshaft speed required toachieve a certain pump performance rating. In this section you will be givenparameters for a motor that will be used to drive the pump and a maximumspeed for the crankshaft. From this, you will determine a pulley diameter tomaintain the minimum performance.


11

Determining the Pulley Size

The Relationship Between the Motor and Pulley

The pump will be driven by a belt and motor operating at a constant speedwith an attached pulley.

Given the motor speed, motor pulley diameter, and pump pulley diameter, thepump crankshaft speed can be determined as follows:

Pump Pulley Diameter * Crankshaft Speed = Motor Pulley Diameter *Motor SpeedCrankshaft Speed = Motor Speed * (Motor Pulley Diamter/Pump PulleyDiameter)

Since the pump performance is dependent on the crankshaft speed, the pulleydiameter will affect the performance for a specific motor. The pulley diametershould be added as a key parameter in the spreadsheet and the pulley partadded to the assembly range so that it is included in future updates.

The expression name RPC_pulley_dia will be used for the pulley diameterand included in the expression range for Root Part Cascade updates.


Step 2: Rename the expression for the diameter in the pulley.

Change the work part to ***_pulley.

Rename the expression dia to RPC_pulley_dia.


11


Step 3: Edit the spreadsheet in the assembly to include the pulleydiameter, motor speed, and motor diameter parameters.

Change the work part to ***_pump_assm and invoke theModeling Spreadsheet.

Insert rows in the spreadsheet to include the pulley diameter,motor pulley diameter, and motor speed inputs.

Note

In the example below, a column was inserted to describeall of the parameters. The key parameters used to updatethe model were also separated from non-geometricreference parameters.

2 Key Parameters Values

3 rpc_piston_dia 3.25

4 rpc_throw 2.255 rpc_pulley_dia 867 motor_dia 2.258 motor_rpm 17259 shaft_rpm 485.1563


11


Step 4: Relate the crankshaft speed to the pulley diameter and motorparameters.

Edit the cell containing the value of the shaft_rpm parameterto relate it to the pulley diameter, motor diameter, and motorspeed.

Note

When the formula is inserted in the cell for thecrankshaft speed, the value for it and the performancerating will change. The pulley diameter now determinesthe crankshaft speed and can be modified to achieve thedesired performance.


11


Step 5: Determine a pulley size and crankshaft throw distance to obtain aperformance rating of 150 cu. ft. per minute and a speed of 560rpm.

Decreasing the diameter of the pump pulley will allow you toachieve the desired performance rating of 150 cu ft. per minute,but suppose that the operating speed of the pump cannot exceed560 rpm. To reach both of these target values, you will vary thecrankshaft throw distance and the pulley diameter.

Perform a Goal Seek using the Newton Raphson 2D method todetermine a pulley diameter and crankshaft throw distance.Use the target values and the cells containing the values ofthe parameters shown below.

Variable Cell 1RPC_throw Target Cell 1Performance RatingTarget Value 1150 Variable Cell 2 RPC_pulley_dia Target Cell2 shaft_rpm Target Value 2 560

Use a tolerance of .01, a maximum of 20 iterations, and do notperform a NX update.

2 Key Parameters Values

3 rpc_piston_dia 3.25

4 rpc_throw 2.255 rpc_pulley_dia 867 motor_dia 2.258 motor_rpm 17259 shaft_rpm 485.156310

11 Performance Rating 150.0001


11


Step 6: Add the pulley part to the list of component parts to update.

Add ***_pulley.prt to the list of component parts to update.

13 Update Components

14 ***_pump_crankcase.prt

15 ***_pump_cylinder.prt16 ***_crankshaft.prt17 ***_conrod.prt18 ***_piston.prt19 ***_pulley.prt

Step 7: Update the parts.

Define a new Expression Range with the three key parameters.(Include the cells with the "RPC" expression names and theirvalues.)

Define a new Assembly Range with the six component parts.

Set the Update Method to Root Part Cascade Update.

Update the parts.

Step 8: Update the lift ring location.

The changes to the pulley diameter and throw distance affectedthe center of mass so the lift ring location still needs to be updated.

Define the Expression Range with xlift and ylift parametersand values, change the Update Method back to Work PartUpdate Only, and update the part.

Save the spreadsheet, save and close all parts


unigraphics nx associative parametric design mt10040 workbook

Documents

wave geometry

original layers

outer cylindrical

linked datum

liftboss feature

body reference

lift ring

lift ring