PESIT Bangalore South Campus Hosur road,1km before Electronic City, Bengaluru100 Department of Mechanical Engineering

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1 USN 1 P E PESIT Bangalore South Campus Hosur road,1km before Electronic City, Bengaluru100 Department of Mechanical Engineering INTERNAL ASSESSMENT TEST 2 Date : Max Marks : 50 Subject &Code : Computer Integrated Manufacturing -10ME61 Section : VI B Name of Faculty : Dr.S.V.Satish Time : 90 min Note: Answer any 5 full questions. 1. With a neat sketch explain the following parts feeding system in automated manufacturing: a. Hopper c. Part feeder b. Selector d. Escapement and placement analysis 10 Figure -5 Marks Hopper: This is the container into which the components are loaded at the workstation in bulk i.e., randomly oriented. Parts feeder: This is a mechanism that removes the components from the hopper at a time for delivery to the assembly workhead. The hopper and parts feeder are often combined into one operating mechanism. Selector: A selector is a device that acts as a filter, permitting only parts that are in the correct orientation to pass through. Components that are not properly oriented are rejected back into hopper Escapement device: The purpose of the escapement device is to remove components from feed track at time intervals that are consistent with the cycle time of the assembly workhead.

2 explaniation of all- 5 marks 2. Explain the following: a. Vehicle guidance and routing Method by which AGVS pathways are defined and vehicles are controlled to follow the pathways Three main technologies: Imbedded guide wires - guide wires in the floor emit electromagnetic signal that the vehicles follow Paint strips - optical sensors on-board vehicles track the white paint strips Self-guided vehicles - vehicles use a combination of Dead reckoning - vehicle counts wheel turns in given direction to move without guidance Beacons located throughout facility - vehicle uses triangulation to compute locations b. Quantitative analysis of AGV s Analysis of vehicle-based systems From-to charts and network diagrams Types of systems: industrial trucks, AGVS, rail-guided vehicles, and asynchronous conveyor operations Conveyor analysis Single-direction conveyors Closed loop conveyors Recirculating conveyor systems 3. What are the different types of AGV s used in automation industry? Explain AGV system used for unit load and pallets with neat diagram. An Automated Guided Vehicle System (AGVS) is a material handling system that uses independently operated, self-propelled vehicles guided along defined pathways in the facility floor Types of AGV: Driverless trains Pallet trucks Unit load AGVs Unit Load AGV Used to move unit loads from station to station Often equipped for automatic loading/unloading of pallets and tote pans using roller conveyors, moving belts, or mechanized lift platforms 2. Pallet Truck

3 Used to move palletized loads along predetermined routes Vehicle is backed into loaded pallet by worker; pallet is then elevated from floor Worker drives pallet truck to AGV guide path and programs destination 4. Define industrial robot. Explain spherical robot with a sketch. Also mention its advantages, disadvantages and limitations. ISO defines a Industrial Robot as: A robot is an automatically controlled, reprogrammable, multipurpose, manipulative machine with several reprogrammable axes, which is either fixed in a place or mobile for use in industrial automation application. 2+8 Spherical or Polar Coordinates This type of robot uses mostly rotational axes. The axes for the spherical coordinates are 1.q- the rotational axis 2.R- the reach axis 3.b- tile bend-up-and-down axis The work area serviced by a polar coordinates robot is the space between two concentric hemispheres. The reach of the arm defines the inner hemisphere when it is fully retracted along the R axis. The reach of the arm defines the outer hemisphere when it is fully straightened along the R axis. Figure shows the typical robot. 5. Briefly explain the following: a. Robot End Effectors

4 End effectors can be grippers are tools. Grippers need to be designed specifically for a given application utilizing the concept that will be optimum for the purpose. However, it is possible to categorize the parts into some common shapes, such that general-purpose grippers can be made available. For example, a few of the types of general gripper available is shown in Figure. This gripper is used for cylindrical work pieces. The clamping mechanism used in gripper can be broadly classified as 1. Mechanical clamping 2. Magnetic clamping 3. Vacuum clamping Machine tools can be Painting Gun, Welding Torch, Scoop etc., b. Robot Programming Methods The methods used for development of robot programs or more generally called as teaching a robot is as follows: Lead by nose Teach pendant Off line programming Lead by Nose An experienced operator holds the robot hand and completes the operation manually by moving the robot hand to the various positions. The controller will be recording the actual motions, which can then be used to replay later for actual work. This is suitable for spray-painting application, but not for material handling. Teach Pendant in this case a teach pendant which has all the necessary functions to move the robot is used by the operator to do the job. The operator will move the hand to the various positions and records in the memory the various locations and paths taken to complete the program. Later on the same program can be used for regular operation. This is the most commonly used method for material handling application. Off Line Programming These are generally used with the simulation systems where more sophisticated operations, which involve a number of elements within a manufacturing cell could be simulated. The simulation programs will have the facilities for defining the machine tools, work piece geometries, material handling equipment such as robots, conveyors, etc. After the work cell arrangement is defined, then the movement of robot for work handling can be defined using the simulation language. An actual simulation of the operation can be seen on the workstation screen in wire frame modeling or realistic shaded image to check the validity of the operation. Once approved the robot program can be post processed for the particular robot to be used. 6. Write short notes on: i. Force and Torque sensors: The elementary form of sensors used with grippers, are some form of force or pressure experienced by the gripper fingers while closing on a part. That will indicate the amount of force being applied on the part, which should depend upon the type of component structure and the likely motion of the gripper arm as it is moved in space (the centrifugal forces). ii. Vision sensors

5 The vision sensors include cameras and are used for both process industries and inspection departments. Example: welding robots used for multi pass welding in manufacturing industries. 7. Briefly explain about various types of computer aided process planning-capp. Computer Aided Process Planning (CAPP) can be defined as the functions which use computers to assist the work of process planners. In general, three approaches to CAPP are traditionally recognized: the variant approach, the generative approach, and the hybrid (semi-generative) approach 10 The variant approach, which is also called retrieval approach, uses a group technology (GT) code to select a generic process plan from the existing master process plans developed for each part family and then edits to suit the requirement of the part. Variant approach is commonly implemented with GT coding system. Here, the parts are segmented into groups based on similarity and each group has a master plan. In a generative approach, a process plan for each component is created from scratch without human intervention. These systems are designed to automatically synthesize process information to develop a process plan for a part. Generative CAPP systems contain the logic to use manufacturing data bases, knowledge bases and suitable part description schemes to generate a process plan for a particular part. A hybrid planner, for example, might use a variant, GT-based approach to retrieve an existing process plan, and generative techniques for modifying this plan to suit the new part 8. Write short notes on: a. Material requirement planning MRP "MRP is a computational technique which converts the master schedule for end products into a detailed schedule for raw material and components used in the end products." The detailed schedule identifies the quantity of each material and component items. It also tells when each item must be ordered and delivered so as to meet the master schedule for the final product. The main purpose of MRP is to ensure that materials and components are available in the right quantities and at the right time so that finished products can be completed according to the master production schedule. b. Capacity planning Capacity Planning is concerned with determining the labor and equipment resources needed to achieve the schedule. It also serves to identify the limitations of the available production resources so that an unrealistic master schedule is not planned. Capacity Planning is typically accomplished by two stages as shown in figure

6 Capacity adjustments for short term includes: (a) Employment level. Employment in the plant can be increased (or) decreased in response to changes in capacity requirements. (b) Temporary workers. Increase in employment level can also be made by using workers from a temporary agency. (c) No of work shifts. The number of shifts worked can be increased (or) decreased. (d) Labor hours. The number of labour hours/shift can be increased (or) decreased to the use of overtime and reduced hours. (e) Order backlogs. Deliveries of the product to the customer could be delayed during busy periods when production resources are insufficient to meet the demands. (f) Sub contracting. It involves in getting the work done by others. Capacity planning adjustments for the long term includes: (i) New equipment investment: It involves investing more machines to meet the increased future production requirements. (ii) Purchase of the existing plant (iii) New plant construction. (iv) Plant closing, etc. B.E/6 th sem * ** ** *** (PESIT-BSC Internal Document)