Week 8:- 3D Finishing - Challenges 1

Q.1)

• While finishing the design the nominality of holes is checked which ensures the easy assemble of all the units.
• The hole concentricity and the hole sizes are checked which ensures the easy assembly of all the units.
• The gap between the different units are checked to ensure the proper individual working of different units.
• Designed the rough locators which help to loading a panel in correct position
• Designed the pnumatic layouting for pneumatic connection.
• Gun study is the major and most important part in 3D finishing.
• Selection of sensors solenoid valves as per the requirement and implementing in design.
• Fastners are implemented as per the hole size & the standard color codes as per the curtomer requirement are applied to differentiate tthe type of hole wheather its dowel hole,threaded hole or clearence hole.
• Remaining of the assembly & the part is done to give every part a different identity so everyone can identify in which assembly this part is going to be fit.
• After doing all this things the model is sent for simulation and 2D detailing.

Q.2)

• Hole concentricity and the hole size - Hole concentricity is checked and confirmed for all the parts in a unit for easy assembly while finishing the parts.
• Machining area- The machining area in every parts should be designed & the machining area should be highlighted by using standard color codes.
• Nominality- All units dimensions should be maintained nominal to facilitate easy assembly of the unit.
• Holes coloring standard- Color code standard as per the customer requirement should be applied in the 3D finishing due to that its easy to understand whats the function hole.Mostly color codes used for different holes as follows:

1.] Dowel Hole : BLUE

2.] Threded Hole : YELLOW

3.] Clearence Hole/Counterbored hole : SKYBLUE

• Pneumatic layouting-Pneumatic layouting is a collection of different pneumatic pipes which works as a inlet to the pneumatic cylinder.It should be done properly for proper functioning of the units.
• Gaps checking-Proper gap should be maintained between units to avoid the clash between the different units and it has enough space for assemble.
• Fasteners implementation-Fastners should be implemented in all units as per the requirement & load on the part.like bolts, washers,screwss,etc.
• Avoid clash between different part-Proper gap should be maintained to avoid clash.
• Mylar splittting as per panel profile-Mylar splitting should be confirmed while finishing the design.
• Proper renaming of parts/assemblies as per standard-Proper renaming of parts & assemblies should be done while finishing the design hence we can identify each and every parts easilyb with unique identification.

Q.3)

1. A rough locator is part designed to guide the panel on the pins accrodingly.A rough locator can be a standard part or make part.
2. Rough locators are also work as POKA-YOKE.Poka-Yoke is a japneese word which means mistake proofing.
3. Rough locators are used to help locate workpiece in the automation process.Locating refers to the desired location where you want the wokpiece to be when it is getting woked on either by a person,team or robot.
4. The accuracy of the locating components directly affects the consistancy and how the final product will come out.This is why this componets are essential to your setup.
5. It can be called as fool proofing method also .Because due to the rough locator the part cannot be loaded in correct position.
6. The Rough locators set accroding to the angle of the respective panel Hence part can only be loaded in defined direction & orientation.

Q.4)

Following are the points needs to be considered while designing the rough locators.

• Rough locators should be placed at the edge of the car panel,which it has to guide.
• Rough locators has to be placed in the same angle of the car part edge with a minimum distance of 2-5 mm from edge of car part.

• Rough locator should guide the panel in pin arresting direction.
• Rough locator should start guiding the panel before 10-15mm to the start of the pin engagement.
• Rough locator should be designed with entry angle for the car panel.Generally it ranges between 30-45 degree.
• Rough locators should be designed with two slots to mount the easy adjustments.
• The slots should be in the direction of car part guiding.

Q.5)

• Welding is predominantly used in automobile industries and requirements for fixtures that ease the welding process is a contineous development task in any industry.
• Car Body-In-White(BIW) is a complicated steel structure including 300-500 sheets with complex shapes and are assembled by means of welding in a high rhythm through 55-75 robotic work stations.

• The formost step taken before starting the design of welding fixture is to arrive at the spot welding locations.The location and orientation of other critical units of the fixture including clamps,Locators etc.are decided based on the weld spot distribution.
• It includes the study of weld matrix & the weld point positions.There are two types in weld point one is geo weld points which ensures the geometry of the assembly & second is the respot weld points which added strength to the already welded part.
• It include sthe stjdy of weld gun ( A portable device for semi automatic welding of parts of various articles)which is going to be used for the operation depending on the size of the part,Thickness of part etc.
• In weld gun study the gun which is going to be used while spot welding is checked over the panel by using the 3D software.
• The fixture is designed for the car panel to hold it on the position, The weld gun position is checked over the predefined spot weld points,Weather the gun fall to the fixture unit or not.
• If the gun is fall to the fixture unit then redsigning of that unit or the repositioning of that unit is done & again confirmed wheather the gun is falling or not.
• Fixtures are redesigned if the gun is fall to the fixture unit,the weld spot positions remain same.
• The weld spots are defined on the predescribed locations.The axsis of weld spot along welding directions must be normal to the weld surface.

Q.6)

Weld gun study is very time consuming process ,The entire welding cycle time study depends on the no. of spot and the weld gun study.

Folllowing are the points need to consider during gun study.

1. The axsis of weld spot along weld diretion must be normal to the weld surface.
2. The no. of weld spots for the panel, the time required to spot the each weld & the total time required to complete all the weld spots.
3. If we have one or more device models and we want to program ,The behavious of each model in the work cell can be simulated over time.Instructions for each device for are coded by giving sequence.The sequence defines the motion,manipulation and action of the devices.Based on the distances of each tag point from home positions,motion type,speed and acceleration-one can obtain cycle time for each device assigned with sequences.This way robot cycle tiime is precisely calculated.
4. After sequencing all the devices,a simulation is run with "collision check"ON and made sure that the welding operation collision free..
5. There should be adequate space between Weld gun and fixture unit.
6. Make changes in fixture If there is any collision with spots or with fixture unit.

Q.7)

• A pneumatic system should be efficient and leak free.Sometimes they are not because of improper tube line routing_the result of either lack of knowledge,or corners cut on planning time,or both.
• What can go wrong if routing is not done properly?All kids of things!from not being able to acess fittings for efficient maintanence all the way to leaking connections,inefficent or poor tube routing can create unintended issues that need to be addressed.An ounce of planning is worth a pound of troubleshooting.
• Planning tube line routing is a time invesment It can have a big ROI--espicially for complex systems.During system design,routing should be developed as the next step after sizing the tube lines and selecting the appropriate fittings.

Here are guidelines for appropriate tube line routing:

• Leave fitting joints as accessible as.Inaccessible joints are difficult and time consuming to assemble,tighten and service.
• Use software tools to make labour intensive calculations such as pressure drop.
• Employ U-bend to allow line contraction and expansion.
• Include offset bends to allow for motion under load,regardless of how 'rigid' the system seems.
• Favor bends rather than stright line tube assembly with no bends,like the example of the test stand mentioned above,can cause joint stain,which may lead to leaking.
• Make sure routing design allows room for assembly of any connections required.
• Minimize pressure drop by getting around obstaction with a few 90 degree bend as possible.Only 90 degree bend has more presure loss than two 45 degrees bends.
• Route line around rather than over areas that require regular acess or maintancence.
• Design routing and clamping in mind .Approprate design leads logically to proper clamping.Often its possible to clamp several lines together.
• Keep troubleshooting and maintanece in mind : focus on logical design and avoid crossed lines.
• Design the tube line routing to reduce likelihood of users standing or climbing or plumbing.

Q.8)

Solinoid valves are elecrically activate valves,Typically used to control the flow or ddirection of air or liquid in fluid power systems.Used in both pneumatic and hydraulic fluid power functions,The spool or poppet design of most solenoid cvalves make them perfect for various functions and applications.

The spool or poppet valve connects to a ferrous metal which is typically spring centred or spring offset,but maybe detented instead.The plunger slides within a core tube of nonFerrous metal,Itself surrounded by a coil of electric windings.The coil ranges with any range of voltage fom 12-48 vdc to 110-220vac.When power is series though coil,a magnectiic field is created,which pushes or pulls the plunger,shifting the valve.

The most solinoid valves are two way,teo position poppet valves,which simply open and close,modifying the flow pathwhen their coil is energized.THey are available as "normally open" and "normally colsed",which means normally flowing and normally blocked,respectively.Normally open in fluid conttradicts normally open in electronics,Which stands for the switch or contact open and not flowing electrons.

Three way two poppet valve are also common,diverting flow from one channel to another.Two 3/2 valves in parellel can be used to control a cylinder bidirectionally.Althrough construction varies depending on the use,THis type of valve can be used for either pneumatics or hydraulics,but is more common to pneumatic systems.

Spool solenoid valves consists of a mechanical spool which slides within a mechanical valve body.one or both ends of spool are acted upon by a plunger,and when activated by a either coil,pushes the spool oneway or the other,allowing three positional envelops.The 4/3 hydraulic solinoid valve is one of the most popular,allowing for bidirectional control a cylinder or motor from a single valve body.The "ways" of a solinoid valve refer to how many ports it contains,and the "positions"of a solinoid valve refer to how many descrete states in which it operates.A three position valve employes a spring centered neutral state along with two actuated positions.

For bidirectiomal motor or cylinder control,pneumatic valves are machined with five ports,and are reffered to as 5/3 valves are common practice.The "ways" of a pneumatic valve also include its exhaust ports,to which there are usually two.Occassionally these same valves are described as 4-way,3 position valves,eventhrough close inspection reveals the two exhaust ports bisecting the pressure port.

Solenoid valves for either hydraulic or pneumatic applications are availabe as manifold -mounted modular units,such as the pneumatic or hydraulic ISO valves.These valves contain standard mounting and porting patterns,Permitting valves from any manufacturer to be installed upon the same manifold.Most often these valves are Quite economical and readily available "offf-the-shelf".

Q.9)

• Valve bank is the arrangement of no. of solinoid valves.

• Valve bank will have common inlet port,A single servo line to each of the pneumatic valves,and independent vent passage for each solenoid.
• On the solinoid bank,each of the solinoid valves seperately controls the feed of high pressure servo air to a single pneumatic valve.
• The valve is actuated by a Selectively energising the corresponding solinoid to allow servo air to the servo port of the valve.To return the valve to its fail-safe position,The solinoid is de-energized to vent the servo port of the valve to ambient.The solinoids are two stage pilot valves and are normally open with the solinoid de-energized,allowing high pressure supplyair to the servo ports of the downstream pneumatics valves.Energizing the solinoid blocks high high pressure air supply and simultaneouly vents the pneumatic valve servo chamber to atmosphere,closing the respective pneumatic valve.
• The two stage solinoid are designed to provide fast response times.The electrical configrations is a dual - coil reduntent design providing an isolated circuit topology housed in a single package.Each coil is independent and identical in function.

Q.10)

• The sensors can be defined as a device which can be used to sense or detect the physical quantity like force,pressure,strain,light etc.And then convert it into desigred output like The electrical signal to measure the applied physical quantity.In few cases,a sensor alone maynot be sufficient to analyse the obtained signal.In those cases,a signal conditioning unit is used in order to maintain sensor's output voltage levels in the desired range with respect to the end device that we use.

• In signal conditioning unit,the output of the sensor maybe amplified,filtered or modified to the desired output voltage.For example,if we consider a microphoneIt detects the audio signal and converts to the output voltage which becomes hard to drive an output circuit.So signal conditioning unit is used to increase the signal strength.But the signal conditioning may not be necesssary for all the sensors like photdiode,LDR,etc.
• Most of the sensors can't work independently.So,sufficient input voltage should be applied to it.Various sensors have different operation ranges which should be considered while working with it else the sensor may get damaged permenently.

Q.11)

The following is the list of different types of sensors that are commonly used in various applications.All these sensors used for measuring one of the physical properties like Temperature,Resistance,Capacitance,Conduction,Heat transfer,etc.

Light sensor:

• IR Sensor(IR Treansmitter/IR LED)
• Photodiode(IR Reciver)
• Light Dependent Resistor

Teperature Sensor:

• Therimstor
• Thermocouple

Pressure/Force/Weight Sensor:

• Strain Gauge(Pressure Sensor)
• Load cells(Weight Sensor)

Position Sensor:

• Potentiometer
• Encoder

Hall sensor:

Flex Sensor:

Sound Sensor:

• Microphone

Ultrasonic sensor:

Touch sensor:

PIR Sensor:

Tilt Sensor:

• Accelerometer

Gas Sensor:

We need to select the desired sensor based on our project or application.As said earlier in order to make them work proper voltage should be applied based on their specifications.

Q.12)

Basic fundamentals for sensor unit design:

• Sensor unit is unit designed to sense the car panel by using electrical sensors.
• The signal from sensors wil be fed to the PLC and so the next process will be executed will be this signal.
• Sensors are used for the confirming their is panel/component present or not.
• It helps to avoid human error.
• Basically sensors should be equal numbers as came to number of panels in a assembly.For eg. If 9 pannels are in assembly,so there should be 9 sensors used.
• Sensors should be slot is designed in such a way that it can be adjusted in 3 direction.
• Sensors are also used for safety purpose of operator.
• Typically proximity,LASER,Photo electric sensors are used in Fixtures.
• Some major sensor manufactures are IFM,Pepperi-functions,SICK,OMERON,etc.