BIW FIXTURES-3D-FINISHING THEORY

1.3D-Finishing:It is the process before sending the part for final simulation.The part should be checked for all proper clearences and representing the maching sides of a part by applying colour codes.In this process the part is checked with hole concentricity,designing of rough locators for guiding the panel.Fasteners are implemented as per the hole size & the standard color codes as per the customer requirement are applied to differentiate the type of hole,wheather its Dowel hole, threaded hole or Clearance hole.Renaming 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 these things the model is sent for simulation & 2D detailing.

2.Points need to be taken care while designing a part:

• Put Hardware items in the design.
• Make all the in all the parts wherever it is required.
• Finishing the sketch as per the standard practice.
• Provide openings in design.
• Split the mylar with the car panel.
• Use the standard colour as per the customer standard.
• Provide machining cut as per the design.
• Provide Flame cut shape in the parts wherever it is required.
• Renaming the Tree structure as per the customer standard.
• Provide standard colours to the holes.
• Checking links of the parts with the appropriate Assemblies.
• The nominality of holes to be checked for easier installation of Fixtures.
• Hole concentricity to be checked.
• Gun study to be done for clearences.
• Rough Locaters to be designed to guide the panel while manual installing.

3.Rough Locators & its Use:
Rough locators are used to help locate workpieces in the automation process. Locating refers to the desired location where you want the workpiece to be when it is getting worked on either by a person, team, or robot.It is a device to establish and maintain position of a part in a jig or fixture.They usually feature a 35mm bend at 60° with a height from bend ranging from 65mm to 320mm. The width of these locators are 19mm, 32mm depending upon the standard we are using.Rough locators are also work as Poka-yoke.Poka-yoke (ポカヨケ, [poka yoke]) is a Japanese term that means "mistake-proofing" or "inadvertent error prevention". A poka-yoke is any mechanism in any process that helps an equipment operator avoid (yokeru) mistakes (poka)..Rough locators are used to help locate workpieces in the automation process. Locating refers to the desired location where you want the workpiece to be when it is getting worked on by a person.The accuracy of the locating components directly affects the consistency and how the final product will come out.It can be called as fool proofing method also.Fool Proofing is a method by which ensures that the workpiece will fit into the work holder only if the workpiece is placed in the correct position. Because due to the rough locator the part cannot be loaded in incorrect position.The rough locators are set according to the angle of the respective panel hence part can only be loaded in defined direction & orientation.

4.Points to be considered while designing a Rough Locator:

• Locators should contact the work (preferably machines surface) on a solid and stable point:This permits accurate placement of the part in the tool & ensures the repeatability of the jig and fixture.
• They should be placed as far as possible:This permits the use of fewer locators & Ensures complete contact over the locating surface.
• Ensures that the part fits into the tool in its correct position.
• Rough locator has to be placed in the same angle of the car part edge with a minimum distance of 2-5 mm from the edge of the car part.
• It should start guiding the panel before 10 to 15mm to the start of the pin engagement.
• It should be designed with entry anglle for the car panel. Generally it ranges between 30-45 degree.
• It should be designed with two slots to mount the easy adjustments.The slots should be in the direction of car part guiding.

5.Gun study:
Welding is predominantely used in automobile industries and requirements for fixtures that ease the welding process is a continuous development
task in any industry.Car Body-In-White (BIW) is a complicated steel-structure including 300~500 sheets with complex shape and are assembled by means of welding in a high rhythm through 55~75 robotic work-stations.The foremost step taken before starting the design of welding fixture is to arrive at the spot weld locations. The location and orientation of other critical units of the fixture including clamps, locators etc., are decided based on the weld spot distribution. The weld spots for Front door inner panel Side bracket assembly are located as shown in Table 1 with respect to the body line of car.It includes the study of the weld gun (A portable device for semiautomatic welding of parts of various articles) which is going to be used for the operation depending on the size of the part, Thickness of the part etc.It includes the study of the 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 Re spot weld points which adds strength to the already welded part.

The device used to make sopt welding on the panel is called Gun.The Gun may differ depending upon the application.Fixtures will be designed by considering the weld spots on the panel.After designing the Fixture the CAD file of the gun be placed on the weld spots to check wheather the Gun is clearences with the Fixture.After adjusting the Fixtures the cordinates of the welds be taken for further operations of Weld Gun.

6.Points to be considered during the Gun study:

• The axis of weld spot along welding direction must be normal to the weld surface.
• 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.
• If we have one or more Device models and we want to program; the behavior of each model in the work cell can be simulated over time. Instructions for each device are coded by giving Sequences. The sequence defines the motion, manipulation and action of the devices. Based on the distance of each tag point from home position, motion type, speed and acceleration – one can obtain cycle time for each device assigned with sequences. This way robot cycle time is precisely calculated.
• After sequencing all the devices, a simulation is run with "collision check" ON and made sure that the welding operation is collision free.
• Their should should be adequate space between weld gun and fixture unit.
• Make changes in fixtures if their is any collision with spots or with fixtures unit.

7.Pneumatic Routing:Hydraulic, pneumatic or lubrication systems 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 kinds of things! From not being able to access fittings for efficient maintenance all the way to leaking connections, inefficient or poor tube routing can create unintended issues that need to be addressed. An ounce of planning is worth a pound of troubleshooting.
Guidelines for planning appropriate tube line routing:

• Leave fitting joints as accessible as possible. Inaccessible joints are difficult and time-consuming to assemble, tighten and service.
• Use software tools to make labor-intensive calculations such as pressure drop.
• Employ U-bends to allow for line contraction and expansion.
• Include offset bends to allow for motion under load, regardless of how ‘rigid’ the system seems.
• Favor bends rather than straight tube lines, because a straight 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 obstructions with as few 90° bends as possible. One 90° bend has more pressure loss than two 45° bends.
• Route lines around rather than over areas that require regular access or maintenance.
• Design routing with clamping in mind. Appropriate design leads logically to proper clamping. Often, it’s possible to clamp several lines together.
• Keep troubleshooting and maintenance in mind: focus on logical design and avoid crossed lines.
• Design the tube line routing to reduce likelihood of users standing or climbing on plumbing.

So, although generally speaking you want to minimize joints, the the best (most efficient, least likely to leak) path for connecting tubing from one point to another isn’t always the most direct.And finally, proper line routing isn’t just a matter of optimal function, but also achieving a neat appearance. You can always be proud of good design.

8.Solenoid Valve:

A solenoid valve is an electromechanically operated valve.Solenoid valves differ in the characteristics of the electric current they use, the strength of the magnetic field they generate, the mechanism they use to regulate the fluid, and the type and characteristics of fluid they control. The mechanism varies from linear action, plunger-type actuators to pivoted-armature actuators and rocker actuators. The valve can use a two-port design to regulate a flow or use a three or more port design to switch flows between ports. Multiple solenoid valves can be placed together on a manifold.Solenoid valves are the most frequently used control elements in fluidics. Their tasks are to shut off, release, dose, distribute or mix fluids. They are found in many application areas. Solenoids offer fast and safe switching, high reliability, long service life, good medium compatibility of the materials used, low control power and compact design.

Working of solenoid valve:
A solenoid valve consists of two main components: a solenoid and a valve body (G). Figure shows the components. A solenoid has an electromagnetically inductive coil (A) around an iron core at the center called the plunger (E). At rest, it can be normally open (NO) or normally closed (NC). In the de-energized state, a normally open valve is open and a normally closed valve is closed. When current flows through the solenoid, the coil is energized and creates a magnetic field. This creates a magnetic attraction with the plunger, moving it and overcoming the spring (D) force. If the valve is normally closed, the plunger is lifted so that the seal (F) opens the orifice and allows the flow of the media through the valve. If the valve is normally open, the plunger moves downward so that the seal (F) blocks the orifice and stops the flow of the media through the valve. The shading ring (C) prevents vibration and humming in AC coils.

Components of a solenoid valve:coil (A); armature (B); shading ring (C); spring (D); plunger (E); seal (F); valve body (G)

Applications:
Solenoid valves are used in a wide range of applications, with high or low pressures and small or large flow rates. These solenoid valves use different operating principles that are optimal for the application. The three most important ones are explained in this article: direct acting, indirect acting, and semi-direct acting operation.

9.Valve Bank:Valve bank is the arrangement of no. of solenoid valves.Valve bank will have common inlet port, a single servo line to each of the pneumatic valves, and independent vent passages for each solenoid.On the solenoid bank, each of the solenoid valves separately controls the feed of high pressure servo air to a single pneumatic valve.The valve is actuated by selectively energizing the corresponding solenoid to allow servo air to the servo port of the valve. To return the valve to its fail-safe position, the solenoid is de-energized to vent the servo port of the valve to ambient. - The solenoids are two-stage pilot valves and are normally open with the solenoid de-energized, allowing high pressure supply air to the servo ports of the downstream pneumatic valves. Energizing the solenoid blocks high pressure air supply and simultaneously vents the pneumatic valve servo chamber to atmosphere, closing the respective pneumatic valve.The two-stage solenoid are designed to provide fast response times. The electrical configuration is a dual-coil redundant design providing an isolated circuit topology housed in a single package. Each coil is independent and identical in function.

10.Sensor:A device which detects or measures a physical property and records, indicates, or otherwise responds to it.n the broadest definition, a sensor is a device, module, machine, or subsystem whose purpose is to detect events or changes in its environment and send the information to other electronics, frequently a computer processor. A sensor is always used with other electronics.In the industrial automation, sensors play a vital part to make the products intellectual and exceptionally automatic. These permit one to detect, analyze, measure and process a variety of transformations like alteration in position, length, height, exterior and dislocation that occurs in the Industrial manufacture sites.These sensors also play a pivotal role in predicting and preventing numerous potential proceedings, thus, catering to the requirements of many sensing applications.
The following are the various types of sensors used in automation:

• Temperature Sensors
• Pressure sensors
• MEMS Sensors
• Torque Sensors

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

• Temperature Sensor
• Proximity Sensor
• Accelerometer
• IR Sensor (Infrared Sensor)
• Pressure Sensor
• Light Sensor
• Ultrasonic Sensor
• Smoke, Gas and Alcohol Sensor
• Touch Sensor
• Color Sensor
• Humidity Sensor
• Tilt Sensor
• Flow and Level Sensor

12.Selecting a Sensor:Automated test systems have to interact and measure things in the real world. Data on size, distance, strength, weight, pressure, temperature, color, surface finish, and more may be required to perform the test and analyze the results.

1. Accuracy & Precision – These two terms do not mean the same thing, though they are often related. Accuracy has to do with how close the sensor reading is to the true value while Precision refers to the ability of the sensor to detect small changes. (As an example, a temperature sensor that measures boiling water at 97.53°C has high precision but low accuracy.) Both the accuracy and precision of a given instrumentation system must be appropriate for the requirements of the system. Too high of precision can give a false impression that the reading is also accurate or can result in the system detecting noise rather than the actual desired data. A sensor with more accuracy than necessary will be more expensive and more difficult to use properly than one more appropriate to the measurement required. Additionally, both accuracy and precision are affected by errors incurred throughout the system. Transducer error, wiring, signal conditioners, and the gauges or converters used to read the value each add their own errors into the system that must be understood in order to select the appropriate sensors.

2. Environment – The selection of the proper sensor requires a good understanding of the environment in which the instrument will be operated. Many sensors can be affected by the non-ideal conditions of a production floor (such as temperature variation, vibration, humidity, chemicals, etc.) It is important to take the environment into account when selecting the sensor and its packaging, mounting, and other options.

3. Excitation – Many transducers require power to produce an output signal and it is important to provide a power source that will not introduce additional errors.

4. Signal Conditioning – Unfortunately, the world is full of non-ideal realities in sensors. Electrical noise is always present, often more so on production floors, and can cause erroneous readings. Signal conditioners and other protection circuits can provide some protection from these effects before conversion. Sometimes these are useful, but other times it is possible or preferred to process the signals after conversion, so the use of conditioners must be evaluated during the instrumentation design process.

5. Conversion – In modern systems, it is often preferred that the instrumentation system provides digital data (rather than analog gauges or chart recorders). The analog to digital converters must be evaluated and matched appropriately to the sensors or errors can be introduced, or money wasted by overpaying for precision in one that is not present in the other. Make sure to properly handle ratiometric and non-ratiometric sensors by properly matching with converters that are the same.

6. Processing – Even if signal conditioning is performed, the sensor and conversion process is full of various sources of error. Some of these errors are linear (consistent effect across the measurement range), while others are non-linear. There are various methods and algorithms that can be used to compensate for these errors or to extract the best possible signal from the system.

The data ultimately must be displayed or used by the system and may be stored for later analysis. Whatever is done with the data, remember that a test system can only perform as well as the data that it is provided, so appropriate analysis must be done when selecting and implementing the instrumentation.

Duotech Services has extensive experience in using sensors from many different manufacturers for various types of measurement. This experience allows thorough analysis, design, and implementation of instrumentation systems that meet requirements while keeping acquisition and operational costs as low as possible.