ApplicationNote_MichaelWang

8/9/2019 ApplicationNote_MichaelWang

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Introduction

Com(uter!aided Design 2C7D re,ers to the use o, com(uter (rograms to assist in

+oth the (rocess o, designing and the actual design o, (h)sical models. It came +e

used to design cur'es* sur,aces* solids in +oth t-o and three dimensions* as -ell as

im(ro'ing documentation and creating catalogs ,or manu,acturing. "he commercial

C7D industr) +egan in the late %<=>s* -ith a hand,ul o, com(anies de'elo(ing(ro(rietar) main,rame com(uters and 'ector re,resh gra(hics terminals 2Weis+erg.

Modern da) C7D modelling has e'ol'ed ,rom 3D -ire,rame modelling 2-here+)

each line o, the model is manuall) inserted to 3D solid (arametric and e/(licit

modelling 2-here+) ,eatures are added relati'e to e/isting ,eatures* such that

relationshi(s +et-een model geometries are maintained ? allo-ing designers to

easil) ma0e changes to the (art -hile retaining desired design attri+utes.

@or this (roAect* the (rinci(les o, 3D solid (arametric modelling -ere utilied in the

design o, the (in dis(la) matri/ in Siemens NX 8.5. More s(eci&call)* the techni6ue

o, Constructi'e Solid :eometr) 2CS: -as used to de'elo( the &nal dis(la) matri/

2sho-n in @igure %. CS: com+ines the conce(t o, sim(le ;oolean o(erators 2union*di1erence* and intersection -ith sim(le geometric sha(es 2s6uares* s(heres*

c)linders* etc. in order to model the desired (art 2Bead-er0s. CS: is the most

,undamental design (aradigm o, modern 3D modelling* as it is relati'el) eas) to

(ic0 u(* and calls ,or a less a+stract design (rocess -hen com(ared to more

ad'anced methods* such as cur'e modelling and (ol)gonal modelling. Seeing as

this (roAect does not re6uire e/tremel) com(le/ models 2human ,aces* cur'ed

sur,aces* etc.* CS: -as chosen as the design method o, choice.

Figure 1. 3D Model of Pin Display Matrix



Objectives

"he 3D model is a %= / %= (in arra) -ith indi'idual 3D (rinted sla+s* ,orming %=

ro-s o, %= (ins. Each o, these ro-s has indi'idual slots ,or metal (ins to (re'ent

them ,rom +ecoming misaligned. "hese (lates are stac0ed together* and can +e

loc0ed using t-o +olt scre-s on each side. "he initial (osition o, the sheets allo-

the (ins to mo'e easil) -hile (ro'iding enough ,riction to remain at the desired

height. 7,ter each (in is raised to its (ro(er height* the +olt scre-s are tightened*

loc0ing the (ins and ensuring that the heights -ill not change -hen the dis(la) is

+eing ,elt.

Technical Details

"he (in dis(la) matri/ design ,or this (roAect is a %= / %= hole assem+l). It consistso, a series o, thin (lates -ith semi!circle groo'es linearl) arranged these groo'es

are designed such that the (ins -ill +e held static. "he t-o outside (lates are made

signi&cantl) thic0er* in order to minimie e/ throughout the middle o, the (lates

2there,ore distri+uting tension on each (in more e'enl)* as -ell as to im(ro'e the

dura+ilit) o, the entire assem+l). "he (lates are held together 'ia the larger

diameter holes in the t-o side ears o, each (late. 7 +olt is threaded through

these ears* and s(rings are (laced in +et-een each (late around the +olt during the

assem+l) (rocess. "he s(rings are used to ,urther distri+ute tension e'enl)

+et-een (lates* ensuring that each (in -ill re6uire the same amount o, ,orce to

mo'e. "here is also a small circular indented area around each ear hole* so that the

s(rings located in this area are allo-ed slightl) more s(ace. 7 nut -ill +e threadedonto the o(en end o, the +olt to com(ress the (late assem+l).

In addition to holding the (lates together* the +olt and nut also ,unction as a

method to loc0 the (ins in (lace. While it is necessar) ,or the (ins to +e static

-ithout an) e/ternall) a((lied ,orce* -hen the dis(la) is still +eing re,reshed* it is

desira+le ,or the (ins to +e a+le to mo'e -hen the F!a/is actuator is re(ositioning

the (ins. "here,ore* the dis(la) -ill ha'e t-o modes unloc0ed and loc0ed. "he

dis(la) -ill +e unloc0ed -hile the dis(la) is re,reshing* such that (ins -ill +e mo'ed

-hen the F!a/is actuator (resses on them* +ut the (ins -ill still ha'e enough ,riction

to remain in the (osition the) are set to. While the dis(la) is loc0ed* the (ins -ill

not +e a+le to +e re(ositioned -hen su+Aected to ,orces o, the magnitude ca(a+le o,

+eing achie'ed +) the F!a/is actuator* as -ell as human &ngers. "he loc0ed mode

-ill +e used a,ter the dis(la) has +een re,reshed* allo-ing users to ,eel the dis(la)

-ithout the ,ear o, re(ositioning an) o, the (ins. "he loc0ed mode -ill +e achie'ed

+) tightening the nuts to the (oint -here the (ins are no longer mo'a+le -hen

reasona+le ,orces are a((lied to them.



Implementation

Siemens NX 8.5 -as used to create the 3D model in @igure %. "he model is

com(rised o, a com+ination o, e/truded rectangles* holes* and edge +lends. While

an e/hausti'e tutorial on each ste( ta0en in the de'elo(ment o, this model -ould

+e unnecessaril) long and re(etiti'e* a +rea0!do-n o, each maAor design ste( -ill

+e gi'en as ,ollo-s.

Ste( % ! Datum Coordinate S)stem

@or 3D modelling* the datum coordinate s)stem 2DCS is analogous the com(ass o,

a ma(. It is the ,undamental (ositioning tool ,or the entire model. Since the

desired (art is to +e 3D (rinted* the initial DCS is o, less im(ortance than i, the (art

-as designed to +e machined 2-hich in'ol'es intricacies +e)ond the sco(e o, this

a((lication note. @or 3D (rinting* the most im(ortant thing to remem+er is that the

(rinter (rints in la)ers* so o(erating costs can +e reduced i, the (art is designed to

minimie F!a/is height. "he standard to(!'ie- DCS is sho-n in @igure $. 7dditional

DCS (oints -ill need to +e added throughout the design o, this (art* and this -ill +e

discussed -hen necessar).

Figure 2. Datum Coordinate System

Ste( $ ? ;asic S0etching

3D modelling starts o1 as $D modelling. S0etches are $D dra-ings that can +egi'en de(th 2e/truding. "here are a 'ariet) o, s0etching tools a'aila+le to create

di1erent sha(es. Create the +ase rectangle o, the (art +) using the Gectangle tool*

,ound in the tool+ar located at the +ottom o, the NX -indo- 2@igure 3. "he

rectangle dimensions -ere calculated +e,orehand. @or the a/is* since each hole is

$.=mm center!to!center* $.=mm H %= holes 4%.=mm an e/tra .5mm -as added

,or the to( and +ottom edges o, each (late* such that the to( and +ottom holes ,or

each (late are not on the 'er) edges. "his results in a a/is measurement o,



4$.=mm. "he X!a/is -as calculated +) adding 5mm to each side o, the !a/is

calculation 4$.=mm J 5H$mm 5$.=mm. 5mm -as chosen as a reasona+le

thic0ness to add to the end (lates. "hus* a 5$.=mm +) 4$.=mm rectangle -as

created as the +asic sha(e o, the (art 2@igure 4.

7dd t-o additional s0etches to the initial s0etch. Kne is a (oint 2indicated +) the

J in @igure 3* to +e co(ied into the %= / %= arra) o, holes. "he other is anotherrectangle* -ith -idth centered at the a,orementioned (oint. "his rectangle -ill +e

the +asis ,or the channels that run +et-een the (lates. See @igure 5 ,or details.

Figure 3. ool!ar: "e#tangle

Figure $. %asi# "e#tangle S&et#'

Figure (. )dditional Point and "e#tangle S&et#'es

Ste( 3 ? Instance :eometr)



"he Instance :eometr) command is a 'er) (o-er,ul tool. It can +e used to co()

e/isting ,eatures o, a (art#s0etch according to user s(eci&ed (arameters 2distance

+et-een co(ies and num+er o, co(ies* as -ell as -here to (lace co(ies. "he &rst

ste( is to choose the t)(e 2along a (ath* 'ector* mirrored* or rotated. @or this (art*

instance geometr) o+Aects -ill al-a)s +e translated. Ne/t* select the o+Aect that

should +e co(ied 2in this case it is the (oint created in the latter (ortion o, Ste( $. "he direction should also +e s(eci&ed at this (oint 2,or this it is the X!a/is ? select

the X!a/is 'ector that a((ears on the ne- DCS that a((ears. Since each hole

should +e $.=mm C!C* set distance as $.=mm and the num+er o, co(ies as %5 2,or a

total o, %= (oints. "his should result in a s0etch identical to @igure L.

Do another Instance :eometr) command in order to co() the %= (oints %= times*

this time in the !a/is direction. "his should result in an arra) o, %= / %= (oints.

"hese (oints -ill e'entuall) +e turned into the holes ,or (ins in the dis(la). @inall)*

in'o0e )et another Instance :eometr) command* this time using the thin rectangle

also created in the latter (ortion o, Ste( $* in the X!a/is direction. "he &nal result is

sho-n in @igure 8.

Figure *. +nstan#e ,eometry Dialog %ox





Figure /. 0xtrude Dialog %ox

Figure 1. Part after 0xtruding +nitial "e#tangle



Figure 11. Part after 0xtruding 0ars

Ste( 5 ? oles

In'o0e the ole command. It is located in the same tool+ar as the E/trude

command. "he ole dialog +o/ should a((ear 2@igure %$. While s(eci,)ing (oints*

NX should automaticall) select all $5= (oints a,ter manuall) selecting a ,e- o, the

(re'iousl) s0etched (oints. Ma0e the diameter o, each hole %.=mm 2the diameter

o, each (in* and change the ;oolean o(erator to Su+tract. "he Su+tract o(erator

-ill remo'e the material that intersects -ith the selected +od). Select the large

initial rectangle as the +od). "his -ill su+tract material ,rom the initial rectangle.

While the dialog +o/ is still o(en* the (art should re,resh to dis(la) the desired

changes 2@igure %3.

Figure 12. 4ole Dialog %ox



Figure 13. 5iew of Part wit' 4ole Dialog %ox 6pen

Ste( = ? @inishing U(

Using a com+ination o, the (re'iousl) co'ered commands* the rest o, the (art is

easil) generated. "he Sho- and ide command ma) also +e necessar) to access

the interior o, the (art* to create the ear hole indentations ,or increased s(ring

s(ace. "he Sho- and ide command can +e accessed +) na'igating the Edit menu

2Edit ! Sho- and ide. iding certain (lates -ill allo- an easier to access 'ie- o,

interior (lates 2@igure %4.

Figure 1$.

5iew of

+ndented

0ar 4oles

on +nterior

Plates

Results

and

Recommendations



7s can +e seen in @igure %5* the 3D model generated using Siemens NX 8.5 -as

(ro(erl) (rinted. While the %.=mm diameter holes in the assem+l) e/hi+it the

(ro(er amount o, ,orce u(on unmodi&ed (ins* the e'entual goal o, the (roAect is to

use tum+led (ins 2-hich results in less shar( edges and there,ore a more (leasant

e/(erience ,or the end user. "hese tum+led (ins are marginall) smaller in

diameter than the un!tum+led (ins* +ut the di1erence is enough to result ininade6uate ,riction to maintain the desired (in heights. "his -ill +e &/ed in the &nal

design +) decreasing the diameter o, the holes in the dis(la) assem+l).

@urthermore* since the s(rings located +et-een each (late are onl) a((ro/imatel)

the same length* there are sometimes inconsistencies -ith the tension a((lied u(on

the (ins throughout the entire dis(la). "he s(rings must +e trimmed +ecause there

do not currentl) e/ist commerciall) a'aila+le s(rings that are as short as necessar)

to &t in +et-een the (lates 2there is a clearance o, .4mm -ithout ta0ing the

indented area into account ? this 'alue increases to %.4mm other-ise. 7 more

(recise method o, trimming the s(rings must +e de'elo(ed ,or the &nal design.

K'erall* the design o, the 3D dis(la) is a success* and onl) minor re'isions need to

+e made +e,ore +ringing the conce(tual design into the &nal stages o, this (roAect.

Figure 1(. 3D Printed Part



References

Bead-er0s. $=. What is Constructi'e Solid :eometr)O

htt(##---.lead-er0s.com#&les#csg.(d,

Weis+erg* Da'id. $8. "he Engineering Design Ge'olution.

htt(##---.cadhistor).net#

http://www.leadwerks.com/files/csg.pdf

http://www.cadhistory.net/

http://www.cadhistory.net/

http://www.leadwerks.com/files/csg.pdf

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ApplicationNote_MichaelWang