• Labs 10a, 10b, 11a, 11b - These four labs are complimentary, and each week there will be four groups that will rotate through all four labs.
• Group Size: 3 students, 4 rotating stations
• These laboratories will be used to pull together 4 individual control systems into a complete manufacturing control system. Although each group will solve a different control problem, each laboratory will end with all stations in a fully functioning control system.
• These four labs will all use an Allen-Bradley PLC-5 to control the stations.
• The descriptions below will be used to develop a design and ladder logic before arriving at the laboratory. All laboratories are to be done on design sheets like those found in the course notes, or equivalent.
• The basic schedule for the first lab is shown below for the first and second weeks.
• NOTE: In this lab three of the stations use the hole detect to start an operation. Even when the operation is done the hole in the keytag will remain. You must write your program so that after the press has retracted the process will not start immediately. Only after the hole is gone will the program start looking for a new hole. You might want to add another state that waits until the hole is gone.
A PLC will be used for control of a hydraulic cylinder that will shear off keytags.
1. Examine the other components in the lab and determine what is required for proper operation of the shear.
2. Design the controls for the press.
3. Develop the ladder logic required for operation
The shear press will detect when the material is in place for shearing when a hole is detected by an optical sensor mounted. When sensed it will set a bit true in memory (B3:0/0) that will cause the material feeder to stop. A pneumatic cylinder will be actuated to clamp the strip. At this point shearing will begin by advancing the hydraulic cylinder until a hydraulic cylinder advanced limit switch is actuated. At this point the advance solenoid will be turned off, and the return cylinder solenoid will be actuated. This will continue until the retracted limit switch is actuated. At this point both the hydraulic solenoids are turned off. Finally the pneumatic solenoid is released, and the material feeder is allowed to continue.
An AC Output card to output 120Vac.
- pneumatic solenoid to clamp material
An AC Input card to accept 120Vac.
- hydraulic cylinder retracted limit switch
- hydraulic cylinder advanced limit switch
1. Make the electrical connections between the PLC and the shear station.
2. Enter the Ladder logic, and test the module by itself.
3. Integrate the components with the other parts of the system and produce parts.
Objective: a PLC will be used to position a material transport system driven by a stepper motor.
1. Examine the other components in the labs and determine what is required for proper operation of the feeder.
2. Design the controls for the material feeder.
2. Develop the ladder logic required for operation
The feeder uses a stepper motor to advance the material strip. The feeder will continue to advance the material until one of the other machines orders the feeding to stop by setting flags true in memory locations (B3:0/00, B3:0/01, B3:0/02). The stepper motor is driven by specifying direction (we will always go forwards), and each time an output is pulsed it will step forward one pulse. It will take a large number of pulses to move the material one inch. Immediate outputs may make it possible to generate pulses faster that the ladder logic scan rate.
A TTL (transistor) Output card to output 5Vdc.
- each pulse moves the stepper motor one step
- forward/reverse direction selector
An AC Input card to accept 120Vac.
- control power on (master power for the station)
- automatic mode on (must be on for PLC control)
1. Make the electrical connections between the PLC and the feeder station.
2. Enter the Ladder logic, and test the module by itself.
3. Integrate the components with the other parts of the system and produce parts.
Objective: a PLC will be used to control an stamping press.
1. Examine the other components in the lab and determine what is required for proper operation of the press.
2. Design the controls for the press.
2. Develop the ladder logic required for operation
The stamping press will detect when the material is in place for stamping (embossing) when a hole is detected by an optical sensor mounted. When sensed it will set a bit true in memory (B3:0/01) that will cause the material feeder to stop. A pneumatic cylinder will be actuated to clamp the strip. At this point stamping will begin by advancing the hydraulic cylinder until a hydraulic cylinder advanced limit switch is actuated. At this point the advance solenoid will be turned off, a two (or more) delay (0.5s) is required to allow the embossing to occur. After this the return cylinder solenoid will be actuated. This will continue until the retracted limit switch is actuated. At this point both the hydraulic solenoids are turned off. The pneumatic solenoid is released, and the material feeder is allowed to continue.
An AC Input card to accept 120Vac.
- hydraulic cylinder retracted limit switch
- hydraulic cylinder advanced limit switch
- control power on (master power for the station)
- auto mode selected (must be on for plc operation)
An AC Output card to output 120Vac.
- pneumatic solenoid to clamp material
1. Make the electrical connections between the PLC and the press station.
2. Enter the Ladder logic, and test the module by itself.
3. Integrate the components with the other parts of the system and produce parts.
Objective: a PLC will be used to control a variable feed drill
1. Examine the other components in the lab and determine what is required for proper operation of the drill.
2. Design the controls for the drill.
3. Develop the ladder logic required for operation
The drill press will detect when the material is in place for drilling when a hole is detected by an optical sensor mounted. When sensed it will set a bit true in memory (B3:0/02) that will cause the material feeder to stop. A pneumatic cylinder will be actuated to clamp the strip. At this point drilling will begin. There are three modes for controlling the drill described below (We will use mode ii). When the drill is done the pneumatic solenoid is released and the material feeder allowed to continue.
i) Velocity Control - the drill may also be controlled using analog output card for feed velocity, and using digital inputs to measure position. The limit switches are used as in mode i). For drilling the analog output card should produce a voltage about +2V, -10V is used for retracting, and 0V for no motion. The ladder logic below will make the analog output card drive the drill to advance when a bit is set, and retract when a second bit is set, otherwise the drill will be idle.
iii) Position Control - the drill may also be controlled by specifying a target position. The limit switches used in i) should be used to check for errors.
A DC Input card to accept 12Vdc.
An AC Input card to accept 120Vac.
- drill retracted limit switch
- control power on (master power for the station)
- auto mode selected (must be on for plc operation)
An AC Output card to output 12Vdc.
- pneumatic solenoid to clamp material
An Analog Output card will be placed in slot 3 to output -10 to +10Vdc and control drill velocity.
1. Make the electrical connections between the PLC and the drill station.
2. Set up the I/O modules. You will need to make sure the analog output card is also set up. When setting it up use the ‘autoset’ values option. This will pick memory locations for the card to use - take note of these. (You will need to do this again when all of the programs are combined.) The use the ‘insert ladder rungs’ program to put the functions you need in the ladder diagram.
3. Enter the rest of the ladder logic, and test the module by itself.
3. Integrate the components with the other parts of the system and produce parts.