08 MET 230 Lab 8 - Cylinder Circuits

7/24/2019 08 MET 230 Lab 8 - Cylinder Circuits

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Laboratory MET 230L-8

CYLINDER CIRCUITS

Objectives

To understand common cylinder specifications.

To study normal and reenerative cylinder circuit desins.

To determine e!perimentally "o# cylinder circuit desin effects cylinder velocities.

$iscussion

Cylinders

%ydraulic cylinders are available in many common styles and si&es. 'ylinders for uni(ueapplications can be special ordered in almost any si&e. )iure 8-* is a s+etc" of a sinle ended

"ydraulic cylinder. ,everal c"aracteristics are used to specify cylinders. %o#ever t"e t"ree most

common c"aracteristics used to specify a cylinder are its bore rod diameter and stro+e lent".Typically t"ese c"aracteristics are typed or stamped on t"e cylinder in t"e format of ore / od

diameter / ,tro+e. )or e!ample 13 / 48 / *25 #ould correspond to a cylinder #it" a t"ree

inc" bore 48 6 diameter rod and a one foot stro+e lent".

Figure 8-1 Single ended cylinder

T"e velocity of a piston is a function of flo# and cylinder areas. T"ree areas c"aracteri&e acylinder. T"ese are t"e cap area annulus area and rod area. T"e cap area 7c is defined as t"e area

of t"e "ead end of t"e cylinder. T"e "ead end of t"e cylinder is t"at end #"ic" "as no mec"anical

penetration. T"e rod area 7r is simply t"e area of t"e piston rod. T"e annulus area 7a is

e(uivalent to t"e difference of t"e cap and rod areas.

303*33 ev. 24224*9 :ae * of 2


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Cylinder Circuits

Normal Cylinder !eration

)iure 8.2 is a eneral sc"ematic of a system #"ic" is plumbed to accomplis" 6normal cylinder

operation. ;nder normal operation cylinder e!tend and retract velocities are strictly functions of

pump flo# and cylinder areas.

Figure 8"# Normal cylinder circuit

)iure 8.3 s"o#s "o# t"e pump flo#


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VQ

Aext

p

c

=

1*5

@"ere?

Ae!t is t"e cylinder e!tend velocity


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)iure 8.B is a eneral sc"ematic of a system #"ic" is plumbed to accomplis" reenerative cylinderoperation. ;nder reenerative operation cylinder e!tend velocity is a function of pump flo#

cylinder e!"aust flo# and cylinder areas. 7 cylinder=s piston velocity is proportional to input flo#.

@it" a constant flo# to a double actin sinle end rod cylinder piston retract velocity is reatert"an piston e!tend velocity. T"is is a result of t"e different volume re(uirements.

7 met"od of increasin rod e!tension velocity #it"out increasin pump si&e #ill be studied and

observed in t"is e!ercise. >ncreasin piston e!tend velocity is accomplis"ed by usin cylindere!"aust flo# to supplement pump flo# durin t"e e!tend motion. T"is process is called

reeneration.

Figure 8"' Regenerati&e cylinder circuit

)iure 8. s"o#s "o# t"e return flo#


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VQ Q

A

Q V A

A

Q

AV

A A

Aext

p r

c

p ext a

c

p

cext

c r

c

=

+

=

+

= +

15

V

Q

A

A A

A

Q

Aext

p

c

c r

c

p

r

=

=

*

@"ere?

Ae!t is t"e cylinder e!tend velocity


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*. >dentify t"e osc" test stand t"at you use to run tests. ecord t"e stand number in Table 8.*.

2. 'omplete t"e sc"ematic iven in )iure 8-9 by usin 7utomation ,tudio.

3. Obtain all of t"e information outlined in Table 8.* for t"e stand c"osen in procedure *.

B. ;sin t"e information in Table 8.* compute t"e follo#in 1use metric units5?

'ylinder cap rod and annulus areas 1mm25.

ated pump flo# 1L4min5.

E!pected cylinder e!tend and retract velocities based on rated pump flo# 1m4s5.

,"o# all calculations in t"e calculation section or on an attac"ed #or+s"eet. ecord t"e results

of all calculations in Table 8.2

. uild t"e normal cylinder circuit as in )i. 8.9. ;se a lever-operated directional valve to control

t"e cylinder. ead t"e flo# rate on t"e flo# meter.

9. ;sin t"e information obtained in procedure calculate t"e e!tend and retract velocities basedon actual pump flo#. ecord t"e results in Table 8.2.

D. ecord t"e system pressure #"ile t"e piston is in motion and after it "as reac"ed t"e end of itsstro+e.

. 'alculate t"e force developed #"ile t"e rod is in motion and #"en it "as reac"ed t"e end of itsstro+e.

9. epeat procedures D and 8 t"is time actuatin t"e directional control valve suc" t"at t"e cylinderretracts. ecord all information in Table 8.2.

D. E!tend t"e rod and record t"e time of travel. )rom t"is time calculate t"e piston velocity.

8. etract t"e rod and record t"e time of travel. )rom t"is time calculate t"e piston velocity.

. E!tend t"e rod and record t"e flo# as indicated on t"e flo# meter durin t"e e!tend motion.)rom t"is flo# readin calculate t"e piston velocity. Note*Pay close attention to what flow the

meter is reading.

*0. etract t"e rod and record t"e flo# as indicated on t"e flo# meter durin t"e retract motion.

)rom t"is flo# readin calculate t"e piston velocity. Note*Pay close attention to what flow the

meter is reading.

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)art # Regenerati&e Cylinder !eration

*. 'omplete t"e sc"ematic > 7utomation ,tudio iven in )iure 8-D to reflect t"e circuit you

constructed on t"e osc" test stand.

2. ;sin t"e information in Table 8.3 compute cylinder cap rod and annulus areas. ,"o# all

calculations in t"e calculation section or on an attac"ed #or+s"eet. ecord t"e results of all

calculations in Table 8.B.

3. 'alculate e!pected e!tend and retract velocities based on actual pump flo# for bot"

reenerative and normal operatin modes. ecord t"e results in Table 8.B.

B. 7ctuate t"e directional control valve to cause t"e cylinder to e!tend. ecord t"e system

pressure #"ile t"e piston is in motion and after it "as reac"ed t"e end of its stro+e.

. 'alculate t"e force developed #"ile t"e rod is in motion and #"en it "as reac"ed t"e end of its

stro+e.

9. epeat procedures B and t"is time actuatin t"e directional control valve suc" t"at t"e cylinderretracts. ecord all information in Table 8.B.

D. E!tend t"e rod and record t"e time of travel. )rom t"is time calculate t"e piston velocity.

8. etract t"e rod and record t"e time of travel. )rom t"is time calculate t"e piston velocity.

303*33 ev. 24224*9 :ae *3 of 2


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Laboratory MET230L-8 Came? ,mit" Tyler ,ec. 003

'ylinder 'ircuitsLab :artner

Test ,tand F B yello# $ate?*04*420*B

$ata4esults

Figure 8"+ Normal cylinder circuit

Ta,le 8"1 Normal cylinder circuit s!eciications

TEST ST.ND NU/0ER ' YELLTa,le 8"# Results or normal circuit o!eration

Electric Motor Pump

Power 1.1 kW Displacement: 8 cm3/rev

Speed rpm Rated flow: 4.5 /min

115 !olts at 8"#.$ psi

t%ree P%ase at rpm

Directional Control Valve Cylinder

&osc% Part 'o.

#S1W!#SP1!"##$(D

# Dimensions $5)18)4## mm

303*33 ev. 24224*9 :ae * of 2


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303*33 ev. 24224*9 :ae *D of 2


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Figure 8"2 Regenerati&e cylinder circuit

Ta,le 8"$ Regenerati&e cylinder circuit s!eciications

Electric Motor Pump

Power 1.1 kW Displacement: 8 cm3/rev

Speed rpm Rated flow: 4.5 /min

115 !olts at 8"#.$ psi

t%ree P%ase at rpm

Directional Control Valve Cylinder

&osc% Part 'o.

#S1W!#SP1!"##$(D

# Dimensions $5)18)4## mm

303*33 ev. 24224*9 :ae * of 2


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Ta,le 8"' Results or regenerati&e circuit o!eration

303*33 ev. 24224*9 :ae 2* of 2


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'alculations

,"o# belo# all pertinent calculations re(uired of t"is e!ercise. >ndicate #"at units are used in t"e

calculations.

7rea 'alculation7G piH2r

7G B0.mmH2

)orce calculation

) G :47 :G8BDpsi 7G B0.mmH2G .D90inH2

)G 8BDpsi4.D90inH2)G 9BB.lbs

'ylinder Aelocity AAG L4T LG.Bm

Time G Aolume of 'ylinder4 )lo# ate )G *.3I:MG **030.mmH3 vG *9390mmH3

TimeG *9390mmH34**030.mmH3G 0.038BminG 2.3sec

AG.B42.3secG 0.*DBm4sec


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)art #

*. 'ompare t"e calculated piston e!tend velocity in normal mode #it" t"e calculated e!tend

velocity in reenerative mode. %o# muc" faster does t"e rod e!tend in reenerative modeJ@"at accounts for t"is velocity increaseJ

>t ma+es it about 8K faster. T"e velocity increase can be accounted for by t"e additional flo#added to t"e system by t"e fluid e!itin t"e cylinder instead of just e!itin into t"e tan+.

2. @"ic" is faster - reenerative e!tend velocity or retract velocityJ

E!tend because t"e area t"e fluid acts on is smaller #"ic" means a smaller volume "as to be filledallo#in t"e cylinder to retract faster.

3. 'ompare t"e e!tend force #"ile in reenerative mode #it" t"e retract force. $iscuss t"evariation.

E!tend force is around 900lbs #"ile t"e retract is around 300lbs. t"is variation is due to "o# t"efluid >s ran in t"e reenerative system. On e!tend t"ere is added pressure in t"e "i" pressure

line to t"e system from t"e fluid e!itin t"e cylinder. On retract t"e fluid e!itin t"e ot"er side

of t"e cylinder just drains into t"e tan+ not addin e!tra pressure to t"e system.

Documents

08 MET 230 Lab 8 - Cylinder Circuits