2007 PLTW Computer Integrated Manufacturing Final Part C

Project Lead The Way, Inc. Copyright 2007

Computer Integrated Manufacturing

Final Examination

Part C College Credit Performance

Fall 2007 Student Name: ___________________________________ Date: _____________________ Class Period: _____________

Total Points: ____________/50


Section 1A: CNC Programming [25 Points Total] Directions: No simulation software may be used. Study the narrative and the

drawing below, and fill in the missing information in the CNC program. Narrative: Acme Stencil Company has asked you to create a stencil made of low carbon steel. The stencil is created by milling through a piece of stock that is 1/16” thick. All milling is done in single passes. The tool path and code you create will follow the centerlines and center marks in the drawing. The tool path cutting sequence is: A, B, C, E, A the cutting speed for low carbon steel is 100FPM and the feed rate is .002 IPT. All arc centers use absolute coordinates.


[22 points – 1 point each]

NOTE: 1. Symbol () substituted for rapid traverse code on line N18 as per duplicate answer from line N12.

2. Symbol () substituted for linear interpolation code on lines N14 and N16 as per duplicate answer from line N13.

CNC Programming [22 points – 1 point each blank] N1 ; PLTW Part C CNC Fall 2007

N2; Tool library

N3 ; T1 1/8" 4 flute, center cutting end mill

N4 ; T2 1/4" 3 flute, center cutting end mill

N5 ; T3 1/8" 4 flute, Ball end mill

N6 ; T4 1/4" 2 flute, Non-Center cutting End mill

N7 ; Material: low carbon steel, Cutting speed 100 FPM, Feed rate .002 IPT

N8 ________ ; Absolute Coordinates

N9 _________ ; Inch Increments

N10 _________ _________; Tool change to appropriate tool

N11 _________ _________; Spindle on CW at calculated speed

N12 ________ X.411 Y.914 ________; Rapid Traverse to 1/4" above Point A

N13 ________ _________ _________ ; Plunge cut to 1/8" depth at calculated plunge feed rate

N1 X2.397 Y1.311 ________; Cut to Point B at calculated feed rate

N15 ________ X1.783 Y1.190 ________ ________;CCW arc to point C center at D

N16 ________ ________; Cut to Point E (Calculate coordinates of this point to the nearest .001”)

N17 ________ X.411 Y.914 ________ ________; CW arc to point A center at F

N18 Z2.00; Rapid traverse to 2 " above point A

N19 ________ ; Spindle off

N20 ________; End Program


Section 1B: Short Answer Written Response [3 Points – 1 point each] Directions: Answer the following questions about the CNC program. Use complete

sentences to fully convey your answers to the questions. 1.1 What would the X coordinate of point B be if a G91 code were used in the next line of

code after line N13 ? ______________________________________________________________________________________________________________________________________________________________________________________________________

1.2 Given the formulas used in the program, what would the affect on feed rate be if the tool selected for milling had the same diameter but one more flute or tooth than the mill used in the program? ________________________________________________________________________________________________________________________________________________________________________________________________________________________

1.3 Why are their no feed rates in lines N15, N16 and N17?

_____________________________________________________________________________________________________________________________________________________________________________________________________________________


Section 2: Robot Programming [10 Points Total] Directions: No simulation software may be used. Study the program narrative, the

movement order, position coordinates and the graphic below. Fill in the missing information in the robot program using the options contained in the answer bank on the following page. The answer blank items may be used once, more than once, or not on all. Calculate the roll angle for positions 3 and 4 to the nearest 1 degree in order to position the cube squarely on the conveyor.

Narrative: In the following program, the robot (Robot1) picks up a cube from the

pneumatic feeder (output1) and places it on the conveyor (axis 7) in front of sensor 1 (input 1). When the cube is detected by sensor 1, the conveyor starts to run and moves the cube to the other end of the conveyor passing in front of sensor2 (input2). When the cube is detected by sensor 2 the conveyor stops after a brief time delay. This time delay is used to keep the cube out of sensor range so that the program will loop properly. A second robot (Robot 2 is not pictured) picks up the block at position 5 while the first robot is loading another block from the feeder. This process repeats in an endless loop.

The sensors are connected to inputs 1 and 2 and are wired so that a block passing in front of them creates an “On” signal. The conveyor is on axis 7. Robot 1 moves in the following pattern: 2,1,2,4,3,4 repeat.

Position X Y Z Pitch Roll (degrees) 1 0 -250 40 -90 0 2 0 -250 240 -90 0 3 150 200 100 -90 ? 4 150 200 250 -90 ?

Calculated roll angle for positions 3 and 4 (same value) to the nearest degree ______________ The program below is for Robot 1.


START: Turn On Output 1 Turn Off Output 1 __________ Go to Position __________Fast Go to Position __________Speed 5 Close Gripper Go to Position 2 Fast Go to Position 4 Fast Go Linear to Position 3 Speed 5 __________ Go to Position 4 Fast If Input 1 On Jump to __________ Jump to START STARTCONVEYOR: Start Conveyor Axis 7 at Speed 5 in Minus Direction If Input __________On Jump to STOPCONVEYOR Jump to __________ STOPCONVEYOR: Wait 20 (10ths of seconds) __________ Jump to __________

1

2

3

4

Pneumatic Feeder Output 1

Sensor 1 Input 1

Sensor 2 Input 2

5

Robot 1 Robot 2 Pickup position (Robot not shown)

Answer Bank Open Gripper Close Gripper STARTCONVEYOR STOPCONVEYOR Start Conveyor Axis 7 Stop Conveyor Axis 7 START 1 2 3 4 5

Conveyor on Axis 7


3. Factory Simulation [15 Points Total]

Directions: No simulation software may be used. Use the accompanying narrative, diagram and program flow chart to answer the following questions.

A robot loads a work piece on the left side of a machining station. Motor M1 drives the shuttle to move the part to the left and right. M1 clockwise (CW) moves to the shuttle to the left. Motor M2 is used to turn a drill spindle on the right side of the transfer station. Light M3 is across from the phototransistor I3 which is wired such that a high signal is sensed when the light from M3 is hitting the phototransistor. Switch I1 is wired normally open and senses that the shuttle is at the left side, which is the robot loading and unloading position. Switch I2 senses that the part has been moved to the end of the drill stroke. Upon start up the system will be homed to the left side. The drill spindle is shut off during part unloading and loading.

I1

I2

I3

Left

Right


Fischertechniks Program - Flow Chart


3 Part C – College Credit Factory Simulation 3.1 What action must M1 take at A to move the shuttle to the left (CW/CCW/Stop)?

3.2 What output must be activated at B for the phototransistor I3 to operate properly

(M1/M2/M3)?

3.3 What action must the output take at B to allow the phototransistor I3 to operate (On/Off)?

3.4 What number is on the bottom branch at C (0/1)?

3.5 What action must output M1 take at D (CW/CCW/Stop)?

3.6 What is the purpose of checking sensor I3 at E?

A. To determine if a part has already been drilled

B. To determine if the robot arm is clear of the shuttle

C. To ensure the operator is not in danger

D. To determine if a part is loaded

3.7 How many seconds does it take the robot to load the part in the machining center?

A. 0.5

B. 30

C. Over 30

D. Cannot be determined

3.8 When the system is operating properly, what is the purpose of the time delay at F?

A. To allow the drilling cycle to complete

B. To allow the robot to complete loading and retract to a safe position

C. To allow the robot to complete loading and unloading of the part and retract to a safe

position

D. To allow the operator time to observe the machining

3.9 What action must output M1 take to move the part the correct direction at H

(CW/CCW/Stop)?

3.10 Is switch I2 wired Normally Open or Normally Closed, at I (Normally Open/Normally

Closed?

3.11 What action must M1 take at K (On/Off/CW/CCW/Stop)?

3.12 What action must M2 take at N ((On/Off/CW/CCW/Stop)?

3.13 What number goes on the right branch of phototransistor I3 at O (0/1)?

3.14 Is the control of the Machining Station Open Loop or Closed Loop? (Open Loop/Closed

Loop)

3.15 Is the interface of the Robot and Machining Station done by handshaking (Yes/No)?

2007 PLTW Computer Integrated Manufacturing Final Part C

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