Display of Pneumatic System

Advisor: Dr. Ma; Dr. Saadeh

Professor: Dr. Koutsougeras

Student: Val Abbott

ET 494

Table of Contents

Introduction……………………………………………………….…… 1

Purpose………………………………………………………………… 2

Design…………………………………………………………..……… 3

View of 3D Model……………………………………………………... 6

Mass Properties……………………………………………………….... 7

Completed Model………………………………………………………..8

PLC Components and Ladder Logic Programming…………………... .10

Flow Chart………………………………………………………………16

Obstacles………………………………………………………………...17

Deliverables…………………………………………………………......19

Bill of Material………………………………………………………….19

Specifications……………………………………………………………20

References…………………………………………………….………...29

1. Introduction

Pneumatics is a section of technology that deals with the study and application of pressurized

gas to produce mechanical motion. Pneumatic systems that are used extensively in industry, and

factories are commonly plumbed with compressed air or compressed inert gases. This is because

a centrally located and electrically powered compressor, that powers cylinders and other

pneumatic devices through solenoid valves, can often provide motive power in a cheaper, safer,

more flexible, and more reliable way than a large number of electric motors and actuators.

Pneumatics also has applications in dentistry, construction, mining, and other areas (Wikipedia).

Examples of pneumatic system and components

Fig.1 Pneumatic System

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2. Purpose

The objective of this project is to demonstrate the different functions of commonly used

pneumatic components, such as a pneumatic actuator, by constructing a functional pneumatic

system. This will be done by designing and building an excavator style arm that will be

pneumatically powered. The idea behind building an excavator style arm came from a balsa

wood model I made at my apartment shown in Fig2. The model was designed to represent fluid

power in liquid form.

Fig.2 Balsa wood model of fluid power

This design project will have a preset range of motions which will be programmed

through a Programmable Logic Controller (PLC) as well as the opportunity to be controlled

using joy stick style manual valves. The finished product will be on display at the Sustainability

Center on north campus by summer 2015 for learning purposes.

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3. Design

The goal of the design aspect is to create an excavator style arm with the possibility of

multiple attachments that will directly display multiple components of a pneumatic system. The

model will be created using a 3D modeling program, SolidWorks. The overall specifications of

this design will be directly related to the specifications of the pneumatic actuators used to move

the arm around. The arm will be constructed of either 304SS or 316SS, thus strength of material

will be ignored due to material being much stronger than mechanical power plant. Specs for 304

and 316 hot rolled stainless steel sheets can be found from the tables on p.13-14(figures 14 & 15)

The pneumatic actuators have a 9/16” piston and will be operating at 100psi. The lifting

force can be calculated by the following;

Fig.3 Lifting force calculation

The base of the arm will have two actuators working together so the lifting force from the

base will be doubled which in turn will give a lifting force of about 50lbs @ 100 psi. Since the

lifting force of each actuator is only 24.85 lbs. the entire machine cannot weight any more than

20lbs. Again, this machine is designed for demonstration of pneumatic components. It will pick

up small amount of weight but the purpose of its design is not to pick things up.

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Each pivot point on the arm cannot be metal on metal since it will be used quite often.

The base of the machine will have a machined piece of .998” SS stock that will fit in a steel

flange mount bearing with set screws. This will allow the arm its left and right movement. All

other up and down pivot points will have press in bushings. At Laitram Machinery we machine

UHMW PE (ultra-high molecular weight polyethylene) plastic for pieces that have moving parts

(idler pulleys, wear strips etc.). All pivot points of up and down movement will have press in

UHMW PE bushings. The reason for choosing this style bushing is they are maintenance free

and if they do wear out they can simply be pressed out and new ones installed. UHMW PE has a

very slick surface and will allow these arms to move with little resistance.

In order to obtain traveling distance for the upper arm the following calculation had to be

done. Fig.4 Distance traveled calculation

The manual valves used in this design were easy to pick out. Since the actuators

being used are 2 way, this means I would need a valve capable of switching the port for high

pressure. A 5 port 2 position valve would be sufficient for this application. A single valve of this

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type would allow controllability for a single actuator. Thus meaning I would need 5 valves.

Being that the rest of the pneumatic components used 1/8” NPT and 5/32” push-lock fittings this

narrowed my selection down.

Fig.5 Image courtesy of Automationdirect.com

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4. View of 3D model

Fig.6 Left side view

Fig.7 Right side view

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Fig.8 Mass Properties Image

Mass = 14.217 poundsVolume = 54.732 cubic inches

Surface area = 1018.321 square inches

Center of mass: ( inches )X = 5.528Y = 8.071Z = 9.422

Principal axes of inertia and principal moments of inertia: ( pounds * square inches )Taken at the center of mass.

Ix = (-0.127, 0.385, 0.914) Px = 347.105Iy = (0.683, -0.634, 0.362) Py = 1758.528Iz = (0.719, 0.670, -0.182) Pz = 1765.612

Moments of inertia: ( pounds * square inches )Taken at the center of mass and aligned with the output coordinate system.

Lxx = 1739.416 Lxy = -72.477 Lxz = -162.966Lyx = -72.477 Lyy = 1552.325 Lyz = 497.775Lzx = -162.966 Lzy = 497.775 Lzz = 579.504

Moments of inertia: ( pounds * square inches )Taken at the output coordinate system.

Ixx = 3927.716 Ixy = 561.766 Ixz = 577.509Iyx = 561.766 Iyy = 3248.961 Iyz = 1578.935Izx = 577.509 Izy = 1578.935 Izz = 1939.942

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5. Completed Model and Construction

Fig. 9 Arm after welding

Fig. 10 Arm mounted on platform

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Fig. 11 All components installed

Fig. 12

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Fig. 13 PLC and Wiring

6. PLC Components and Ladder Logic Programming

The Basic & Standard CPU's have eight digital inputs and six digital outputs built-in. The

Analog CPUs have 4 digital inputs, 4 digital outputs, as well as 2 each analog inputs and outputs.

All these DC powered PLCs are mighty controllers as stand-alone units, or you can expand the

I/O (input output) count with up to 8 modules for up to 142 total I/O points (7). Each of the units

click together and are capable of being mounted on a DIN rail.

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Fig 14. PLC w/ expansions

The I/O line-up includes 24 modules to choose from, including both sinking & sourcing

24VDC input & output options, 120VAC input & output modules, and relay modules for those

applications requiring a little more power (7). For my application C0-00DD1-D (sink/source)

PLC was chosen for its capabilities of sinking/sourcing along with a C0-01AC power supply,

C0-16NE3 (sink/source) for PLC input and C0-16TD2 (sourcing) for PLC outputs.

The difference between sinking vs sourcing is very simple. Sinking provides a path to 0

VDC (-DC) and sourcing provides a path to +24 VDC (+DC). Sinking (NPN) and sourcing

(PNP) does not determine whether it is an input or an output. There are sinking inputs and

outputs as well as sourcing input and outputs. The advantage of using the Click PLC is its ability

of allowing current flow in both directions (sink/source).

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Fig. 15 (above) Fig. 16 (below) Diagrams of sink vs source and sink/source.

The Click PLC will be used to control the automated side of this arm. Along with the

PLC electronic valves and position sensors will be used to assist moving the arm. The valves are

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VQC1100N-5 from SMC donated by Intralox and the sensors are CPS-AP-A from automation

direct.

When all the components are connected they will depend on each other to operate

efficiently. When the arm is at rest the sensors at the base of the actuator will send a signal to the

input at the PLC and the PLC will then send a signal to the valve to open. In turn the arm will

raise up. In order to determine if the sensors are reading the position of the actuator a LED will

turn on when the piston is aligned with the sensor. At this moment the PLC will receive signal

and take action depending on what the program says to do. This is how all the sensors and valves

will interact with each other.

Fig 17. (Top) Installed Sensor

Fig 18. (Bottom) Sensor wiring (sourcing)

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During the programming of the PLC different actions can be put in motion at different

times. This can be done by using timers, counters, and/or programming the sensors to send

signals to different valves. When a sensor from one actuator sends signal to a valve that operates

a different actuator you will get simultaneous motion from two different actuators. The PLC gets

formatted differently depending on where your inputs and outputs are connect to the main

module but your inputs are always Yxxx and your outputs are always Xxxx where the lowercase

‘x’ will be filled with a numerical value.

Fig 19. (Above) PLC Layout

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Fig. 20 (below) Ladder Logic

The picture above shows what the ladder logic looks like in the Click PLC programming.

On the first rung (line is blank) you will set an initiation value. In this case DS1=0. On the

second rung you can see that it is set to run when DS1=0. When this equation is satisfied the

PLC will read signal from either X102 or X101 depending on which sensor is lined up with the

actuator piston. If the PLC receives signal from X102 it will send a signal through the output to

valve Y209. The actuator will then move until the next sensor, X101, sends a signal to the PLC.

When signal is received a timer is started, T1. In this program T1 has a set point of 4 seconds.

When T1 is started it will turn on a counter, TD1. On the following line an equation must be

satisfied in order for the next action to happen. When TD1=4 it has an output of DS1=1. This

equation will initiate the next rung in the program. This continues until the bottom line. The

output of the bottom line is shown as DS1=0. This equation will then restart the process.

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7. Flow Chart of Operations

Fig. 21 Flow Chart

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8. Obstacles along the way

There were many obstacles along the road of completing this project. The biggest of all

was software issues. Initially, I began the design process on my laptop which had 2014 version

of Solidworks. Over time I was splitting the design up between home and work. When it came to

the point where I was ready to begin putting the top level assembly together I ran into a major

issue. The software used at home was newer than the software at work which would not allow

me to open parts that had been modeled at home, on my work computer. I needed the model to

be accessible at work in order to use the templates for our machine shop. I decided instead of

redesigning everything to be accessible at work I would just update all my models to the newer

software which was on my laptop. I asked around the office and found someone who would give

me a copy of the templates on my home computer. Once the modeling was completed all the

technical drawings were completed and a shop order was created. Being that Laitram Machinery

is a manufacturing facility the shop is very busy. They were kind enough to donate all the

material and labor involved in constructing this product. Time was an issue but they made it

happen as fast as possible. After the arm was cut and welded the assembly phase began.

When the arm was constructed I began to learn the PLC programming. Once the basics of

the logic was learned it all came together quickly after that. When I began to incorporate the

manual and automated side into one circuit I soon found out that more parts were needed in order

to get the arm functioning properly. Since each actuator has flow control valves on it these gave

resistance in the system causing air the back feed from the manual side to the automatic valves

which leaked out to the environment. The reason this happened is the valves are 5 way 2 position

meaning air is either applied to one output or the other. So depending on which lever I pulled the

opposing valve on the automated side would leak. I had two options at the time; buy valves that

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had a neutral position or find out how to stop the sir from flowing back to the automatic side. My

solution was to put flow control valves on each output of the automatic valves. This would allow

me to shut the air flow to the automatic valves completely off when I wanted to use the manual

side. The proposed solution worked and the arm functioned as planned.

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9. Deliverables and Timeline

The overall objective of this project was to design and build and arm that would display

different components of a pneumatic system. During the first semester the design of the arm was

completed. During the second semester the arm was assembled and programmed to complete a

set range of movements to display each components function.

Fig.23

10.Bill of Materials

Fig.24 (Above)

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Stainless Steel Specifications

Fig. 25 Table courtesy of alro.com

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Stainless Steel Specifications

Fig.26 Table courtesy of alro.com

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Fig.27 Table courtesy of boedecker.com

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Fig.28 (below) Linear Actuator Specifications (A09060DD-M&A09030DD-M)

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Fig. 29 (below) Angular Gripper Specifications

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Fig.30 (below) Manual Valve Specifications

Part# AVS-527D1-HL

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Fig. 32 PLC Specs

Fig. 31 Power Supply Specs

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Fig. 33 Input Specs

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Fig. 34 Output Specs

References

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(1) AutomationDirect.com | The common sense way to buy industrial controls. (n.d.). Retrieved

November 29, 2014, from http://www.automationdirect.com/adc/Home/Home

(2) Esposito, A. (2009). Pneumatics: Air Preparation and Components. In <i>Fluid Power with

Applications</i> (7th ed., pp. 455-507). Oxford: Pearson.

(3) McMaster-Carr. (n.d.). Retrieved September 29, 2014, from http://www.mcmaster.com/#

(4) Polyethylene Specifications. (n.d.). Retrieved November 4, 2014, from

http://www.boedeker.com/polye_p.htm

(5) Size Types 304L Hot Rolled, Annealed and Pickled Stainless Steel - Plates, Types 304L Hot

Rolled, Annealed and Pickled Stainless Steel - Plates. (n.d.). Retrieved October 29, 2014, from

http://steelandsaw-cutting.fayindustries.com/item/304l-hot-rolled-stainless-steel/rolled-annealed-

and-pickled-stainless-steel-plat-2/types-302-304-304l-hot-rolled-annealed-and-pic-3

(6) (n.d.). Retrieved November 19, 2014, from http://www.alro.com/datacatalog/009-

stainless.pdf

(7)The Almost Free PLC that's so simple, we named it CLICK®. (n.d.). Retrieved May 6, 2015,

from http://www.automationdirect.com/clickplcs/about-click/features

(8) (n.d.). Retrieved May 6, 2015, from

http://www.fluidairecompany.com/docs/pdfs/Q8answer.pdf

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