Automated Port Connection Alignment System

Ray SchroederET 493 Senior Design I

Advisor: Dr. Chris KoutsougerasSpring 2014

May 4, 2014

ABSTRACT.With the advent of electro-hydraulic applications, computer automated test stands used in

quality control have seen advances in complexity and technology to keep up with ever

changing demands. One component these machines are employed to test is fluid gear

motors. Gear motor test stands were developed specifically for quality control in the fluid

power industry where the primary function and use is in the detection of manufacturing

defects in hydraulic gear motors. Defects are identified by automated testing of the gear

motors, after assembly, according to manufacturer specifications and “passed” or “failed”

according to those predetermined conditions. The machines are completely computer

controlled throughout testing thus limiting human error and human involvement with the

exception of loading and unloading test units, hydraulically connecting the test unit, closing

the shielding prior to testing, entering test unit manufacturing data, and starting the test

cycle. To reduce downtime between tests and eliminate complications in hydraulically

connecting the gear motor test unit to the test stand, automated connection of the gear

motors ports to the stand are recommended.

AUTOMATED PORT CONNECTION SYSTEM

INTRODUCTIONLocated at the front of the machine, the test area contains

upper and lower transparent shielding, the Test Fixture, the

gear motor test unit, and all required port connections

necessary to couple the gear motor hydraulically. Currently, a

manual method of connecting the high pressure hydraulic hose

to the test unit is employed, which can be cumbersome and

time consuming considering the rigidity of these hoses due to

their high pressure rating and size, complicating the alignment

of the hydraulic hose end fittings to thread onto the SAE/JIC

fittings installed in the motor. An Automated Port Connection

Alignment system to automatically align port connectors to the

gear motors ports on the test stand would eliminate this

manual labor segment of the test procedure, decreasing

downtime between tests, and allowing an increase in the

number of test units to be output daily.

AUTOMATED PORT CONNECTION ALIGNMENT SYSTEM

METHOD

The test unit motor is mounted into the test fixture and secured with the already present automated test unit clamps. Once secured, the test area shields will

be closed, to provide protection from all moving devices and high pressure hydraulic lines. Upon start of the test, the horizontal portion of the Automated Port

Connection System is actuated, extending outwards to align with the ports on the test unit motor.

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INTRODUCTION - continuedHydraulic hose to motor Port Connector Couplings (PCC)to directly couple the test unit

motor to the test stand will not be offered, the scope of this project will only provide the

vertical and horizontal linear motion systems capable of aligning the PCC mechanism to the

motors ports. For system design and functional real world computer motion simulation, the

Port Connector Coupling will be FOR REFERENCE ONLY and represented by a “Red” colored

block in all documentation.

The extent of the project will consist of using currently available technology in linear motion

systems and the full function of each subsystem, both horizontal and vertical, collectively

will be mechanically simulated using Solidworks Simulation 2013 design software, to show

real world application and real world performance.

METHOD

The test unit motor is mounted into the test fixture and secured with the already present automated test unit clamps. Once secured, the test area shields will

be closed, to provide protection from all moving devices and high pressure hydraulic lines. Upon start of the test, the horizontal portion of the Automated Port

Connection System is actuated, extending outwards to align with the ports on the test unit motor.

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Motion is accomplished using the test stand computer software LABVIEW to control a stepper motor and ball screw. Alignment is accomplished by three

methods, a set number of rotational pulses sent to the stepper motor, a rotary encoder to provide positional feedback to the computer, and from initial

system setup. The rotary encoder’s primary purpose is as a failsafe against the stepper motor losing its position by stalling on route to the objective. Initial

position relative to the stepper motor is accomplished via a mechanical stop at its retracted position to be used as a “home”/”zero” position for the horizontal

system. Position of the horizontal system in relation to the test unit ports will be acquired during system installation using LABVIEW manually by the

programmer during initial setup. The port positions once found manually and stored for the stepper motor and rotary encoder in relation to the

“home”/”zero” position, will be used by the program to determine future positioning of the system.

With the horizontal system aligned with the test unit ports, vertical actuation of the hydraulic cylinders is then performed by LABVIEW to lower the FOR

REFERENCE ONLY port connector blocks to hydraulically couple the test stand to the test unit’s ports. The compact hydraulic cylinders have magnetic pistons

and incorporate low profile body mounted external solid state position switches to provide feedback to the computer to verify the fully extended and fully

retracted positions to ensure proper sequence function. Testing of the motor is then executed as normal.

At the completion or the fail of a test, the vertical system will retract and raise the FOR REFERENCE ONLY port connectors up away from the motor to

hydraulically decouple the test unit from the test stand, sub sequentially the horizontal portion of the system will retract inward to its original starting position

to allow removal of the test unit motor.

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CALCULATIONS

Stepper motor sizing is based on the additional features of each different model of motor

and pricing relative to the size required by the design thus, increasing the design factor. Due

to the location of the motor and the surrounding hydraulic oil a motor with a splashdown

resistant design was needed. A larger motor with higher torque than required was selected

for this feature. A sheet metal cover with open bottom for ventilation will provide

additional hydraulic oil splashdown protection for the stepper motor. Additionally, cost

effective pricing of the stepper motors in the 23 series models also allowed a higher torque

selection with only a marginal increase in price. The higher torque output of the specified

stepper motor will prevent the motor from stalling due to irregular greater than normal

resistance force factors during movement.

Stepper motor sizing based on ball screw torque requirements using a basic 100lb load.

Driving Torque

T d=F∗Ph2π∗η1

∗10−3

Td = Driving torque (N⋅m)F = Axial load (N)Ph = Lead (mm)η1 = Normal efficiency (90%)

F = 100lb ; Ph = .200in

F=100lb*4.44822 = 444.822 Newtons

Ph=.200in*25.4 = 5.08mm

T d=444.822∗5.08

2π∗.90∗10−3

=.3996 N*m

CALCULATIONS

Back Driving Torque

T b=F∗Ph∗η2

2π∗10−3

Td = Backdriving torque (N⋅m)F = Axial load (N)Ph = Lead (mm)η2 = Reverse efficiency (80%)

T b=500∗5.08∗.80

2π∗10−3

= .323 N*m

Drag Torque

T p=

.05√ tanβ

∗F pr∗Ph

2 π∗10−3

Tp = Preload drag torque (N⋅m)

Ph = Lead (mm)Fpr = Preload Force (N)β= Lead Angle (deg)B.C.D. = Ball Circle Diameter

β=tan−1(Ph

π∗B .C .D .)

β=tan−1 5.08π∗.631=68.683

F pr=1.6lb*4.44822=7.117Newtons

T p=

.05√ tan (68.683)

∗7.117∗5.08

2π∗10−3= .178N

CALCULATIONS

Drag Torque

T p=

.05√ tanβ

∗F pr∗Ph

2 π∗10−3

Tp = Preload drag torque (N⋅m)

Ph = Lead (mm)Fpr = Preload Force (N)β= Lead Angle (deg)B.C.D. = Ball Circle Diameter

β=tan−1(Ph

π∗B .C .D .)

β=tan−1 5.08π∗.631=68.683

F pr=1.6lb*4.44822=7.117Newtons

T p=

.05√ tan (68.683)

∗7.117∗5.08

2π∗10−3= .178N

Total driving torque T d+T p=¿ .3996 + .178 = .5776 N*m

Total back driving torqueT b+T p=¿ .323 + .178 = .501 N*m

Total holding torqueT b+T p=¿ .323 + .178 = .501 N*m

Stepper motor bipolar torque = 2.71 N*m

Design factor 2.71/.5776 = 4.71

Gear pulley

Gear pulley sizing was based on a 1:1 ratio basis since no mechanical advantage or speed

increase or speed reduction was needed, so no calculations for gear ratio was required.

CALCULATIONS

Cylinder

Hydraulic cylinder bore sizing based on pressure regulated hydraulic supply tapped from the

test stands pilot supply and the size constraints of the mechanical motion system. Stroke

length was determined from face of test unit’s ports and the Automated Port Connection

System location distance.

Maximum rated cylinder pressure = 2030psi

F=A∗P ; Cylinder Dia = 25mm; Pilot pressure = 1500psi

Diameter conversion 25/25.4=.984in

F=A∗P F=(π .4922) (1500 ) = 1141 lbf

Linear rail

Linear rail sizing dependent on available sizes and moment calculations of hydraulic cylinder

centerline exerted forces with weight of vertical assembly at 15lbs. Smallest size linear

bearing selected based on calculations.

Moment calculations from cylinder centerline to the UPPER linear bearing base:

Cylinder closest to bearing face;

M 1=F∗X1 M 1=1141∗2.08 =2373.9lb*inM 1=2373.9/12= 197.8lbCylinder farthest from bearing face;

M 2=F∗X 2 M 2=1141∗5.73 =6537.9lb*inM 2=6537.9/12=544.8lb

M 1+M2=¿197.8+544.8 +15 = 757.6lb

Maximum bearing load capacity = 3034lb – each

Design factor = 3034/757 = 4

Due to the high design factor using the smallest available sized bearing, one bearing adequately holds loads however, for system rigidity and integrity; two bearings are used in the assembly. Furthermore, due to this high design factor, calculations for the lower bearing not required.

COMPLETION TIMELINE

Fall 2014 semester, ET494;Finalized design by 9/30/14. FEA of machined components by 10/31/14. 3D assembly models and 3D Solidworks simulation of real world system operation and application by 12/5/14.

PROJECTIONS

Automated Port Connection System

Ray SchroederET 493 Senior Design I

Spring 2014ray.schroeder@selu.edu

No Southeastern Louisiana University resource will be used for any part or portion of this project. Intellectual property created, made, or

originated by Ray Schroeder shall be the sole and exclusive property of Ray Schroeder, except as he may voluntarily choose to transfer

such property, in full, or in part.`