Week 8:- 3D Finishing - Challenges 1

Q1: What do you understand by the 3D finish process?

Answer:

3D finish is a process where the design is being completely finished and ready for final simulation & 2D detailing.While finishing the design the nominality of holes is checked which ensures the easy assembly of all the units.The hole concentricity & holes sizes are checked which ensures the easy assembly of different parts.The gaps between the different units checked to ensure the proper individual working of different units.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 whether it’s a simple hole, threaded hole or counterbore hole.Renaming of the assembly & the part is done to give every part a different identify in which assembly this part is going to be fit. After doing all these things the model is sent for simulation & 2D detailing.

Q2: What are the points need to be taken care of while finishing the design?

Answer:

Following points are taken into consideration while finishing the design

Hole concentricity & hole sizes

All parts holes concentricity & holes sizes are checked for easy assembly while finishing the parts.

Machining area.

The machining area in every part should be defined & the machining area should be highlighted by using standard color code. Machining is to be done on parts to properly mount with mating parts. Machining only on desired faces reduces cost & save time also machining increases accuracy of dimension. So before going to simulation or detailing machining area should be defined.

Nominality

All units dimension should be maintained nominal to facilitate easy assembly of the unit.

Holes coloring standard

In 3D finish hole coloring should be done because it helps to identify what type of hole it is?. It depends on customer standard. Customer specifies color like

Dowel hole should be given blue color.

Threaded hole should be colored with yellow.

1. bore or open hole should be given cyan blue color.

Pneumatic lay-outing

Pneumatic layouting is collection of different pneumatic pipes which work as a inlet to the pneumatic cylinder. It should be done properly for proper functioning of the units.

Gaps checking:

The gaps between the different units checked to ensure the proper individual working of different units.

Fasteners implementation

Fasteners should be implemented in all units as per the requirement & load on the part

Avoiding clash between different parts

Proper gap should be maintained between units to avoid the clash between the different units.

Mylar splitting as per panel profile

Mylar splitting as per panel profile should be confirmed while finishing the design.

Proper renaming of parts/ assemblies as per the standard

Proper renaming of parts & assemblies should be done while finishing the design hence we can identify each & every part easily with unique identification.

Q:3 What are rough Locators & what is their use?

Rough locators are usually used in loading & unloading of particular part.

Rough locator unit is apart designed to guide the operator to locate car panel on the pins accordingly. They have slot for adjustment.

Rough locators are used to help locate work pieces 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.The accuracy of the locating components directly affects the consistency & how final product will come out?

A rough locator can be of std. part or make part. It is also work as poka-yoke.

It can be called as fool proofing method also. 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 defined direction & orientation.

rough locator diagram with front top nd side views

Q:4 What are the points you need to consider while designing a rough locator?

Answer:

• Fundamentals of rough locator design
• Rough locators should be placed at the edges of car panel, which it has to guide using locating pins one can easily restrict movement of entire car panel.
• Rough locator has to be placed in the same angle of the car part edge with minimum distance of 2.5 mm from the edge of car part, so it should no damage panel.
• Rough locators should guide the panel before 10 to 15 mm. 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 guide the panel in pin arresting direction in general.
• Rough locators should be designed with two slots to mount for easy adjustment. (in general)
• The slot should be in the direction of car panel guiding.

Q:5 What is the gun study process?

WELD GUN

Welding is predominantly used in automobile industries & 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 & 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 & orientation of other critical units of the fixture including clamps, locators etc., are decided based on the weld spot distribution.

It includes information of weld gun detail, weld matrix & weld points. There are two types of weld points geo weld point & re-spot weld point.

Geo weld points defines the geometry of part & re-spot do all other remaining weld points also add strength to geo weld points. The spots can be geo spots or re-spots shown in figure.

The front door inner panel and side bracket of GM sedan car are to be spot welded as shown in Figure 1. The previously spot welded inner panel assembly is then welded with the cross bracket as shown in Figure 2.

Weld spots for each weld assembly are highlighted in Figure 1 and 2 as WP1, WP2, WP3 and so on.

The Weld points forms the base for fixture design, the clamping plan & locating plan are done 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 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.

Above figure shows different weld guns.

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, whether the gun fall to the fixture unit or not.

If weld gun fall to the fixture unit then redesigning of that unit or the repositioning of that unit is done & again confirmed whether the gun is falling or not Fixtures are redesigned if the gun falls to the fixture unit, the weld spot positions remain same.

The weld spots are defined on the prescribed locations as shown in figure. The axis of weld spot along welding direction must be normal to the weld surface. To ensure this, the weld spot co-ordinates are created using “SURFACE” option under tags in layout menu.

In the IGRIP layout, the motion destination position of a device model is represented by a tag point in a Cartesian co-ordinate frame with N, O & A (or X, Y & Z) axes. To calculate the position of a tag point in the layout, it is attached to a part model. With the attachment, the position of a tag point can be determined with respect to the base coordinate system of the part model to which the tag point is attached. In the database, all tag points in the layout are stored with different names.

Q-6: What re the points need to consider during the gun study?

Weld gun study is very time consuming process, the entire welding cycle time study depends on the no. of spots & weld gun study. Following are the points need to consider during 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 weld spots.If we have one or more device models & 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 & action of the devices. Based on the distance of each tag point from home position, motion type, speed & 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 & made sure that the welding operation is collision free.

Q-7: What is pneumatic routing?

Pneumatic systems should be efficient & 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 thing! From not being able to access fitting for efficient maintenance all the way to leaking connections, inefficient or poor tube routing can create unintended issue that need to be addressed. An ounce of planning is worth a pound of trouble shooting.

Planning tube line routing is a time investment, but can have a big ROI especially for complex systems. During system design, routing should be developed as the next step after sizing the tube lines & selecting the appropriate fittings.

Here are guidelines for planning appropriate tube line routing:

1. Leave fitting joints as accessible as possible. Inaccessible joints are difficult and time-consuming to assemble, tighten and service.
2. Use software tools to make labor intensive calculations such as pressure drop.
3. Employ U-bends to allow for line contraction and expansion.
4. Include offset bends to allow for motion under load, regardless of how ‘rigid’ the system seems.
5. 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.
6. Make sure routing design allows room for assembly of any connections required.
7. 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.
8. Route lines around rather than over areas that require regular access or maintenance.
9. Design routing with clamping in mind. Appropriate design leads logically to proper clamping.
10. Keep troubleshooting and maintenance in mind: focus on logical design and avoid crossed lines.
11. Design the tube line routing to reduce likelihood of users standing or climbing on plumbing.

Q-8: What is the solenoid valve?

A solenoid valve consists of two main components: a solenoid and a valve body (G). Figure 2 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.

Types of solinoidal valves

• 2-way solenoid valve
• 3-way solenoid valve
• Normally closed solenoid valve
• Normally open solenoid valve
• Bi-stable solenoid valve
• Direct acting type
• Indirect acting solenoid valves
• Semi-direct acting type

Q-9: What is the 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, & independent vent passages for each solenoid valve. 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 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.

Q-10: What is sensor & brief about its application in automation?

A sensor is a device that detects and responds to some type of input from the physical environment. The specific input could be light, heat, motion, moisture, pressure, or any one of a great number of other environmental phenomena. ... In a mercury-based glass thermometer, the input is temperature.

A unit designed to sense car panel using electrical sensors is called sensor unit. It is designed to sense car panel using electrical sensor. This signal the sensor will be fed to the PLC & so next process will be executed.

Sensor unit are used actually in sensing whether panel are there or not or particular component are there or not. Suppose there are 9 no’s of part require for assembly then we have that no. of sensor at least. Whenever operator manually assemble entire component they do the process like fastening, gluing. The sensor will show that particular component is there or if component is missing it will give an error.

Sensors used in Automation

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 application.

The various types of sensor used in automation industry are proximity sensors, vision sensors, ultrasonic sensors, position sensors, photoelectric sensors, temperature sensors, inclination sensors etc.

The applications for position sensors as a whole are broad. They can be used in anything from motion control of a robot, tank level sensing or even in semiconductor process equipment.

Displacement sensor is used in the precision of objects at the nanometer level & in the measurement of precision thickness of disk drives, assembly line testing & machine tool metrology. It is widely used in machining.

Q-11 What are the types of the sensor?

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

Q-12 What are the fundamental points that need to consider while designing or selection of sensor?

Fundamental of sensor unit design:

Sensor unit is designed to sense the car panel by using electrical sensors which are being welded in tool.

The signal from sensors will be fed to the PLC & so the next process will be executed.

Each panel should be sensed by 1 to 2 sensor depends on size of panel, preferred to be in diagonal opposite ends of panel. For ex. If 9 panels are in assembly, so there should be atleast 9 sensors used.

Sensor should be used to prevent accidents.

Every sensor should be mounted in 3 directions adjustable way in general.

Some major sensor manufactures are IFM, Pepperi-fuchs, SICK, OMRON etc.