model assignment 3

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                                      FLUID POWER STANDARDS



I agree to the assessment as contained in this assignment. I confirm that the work submitted is my own work.

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This assignment will be used to grade the sections highlighted.

                                             PASS CRITERIA

                                                Assessment Criteria for a pass                     Achieved
                                     •   Recognise and describe given fluid power symbols.
                                     •   Review fluid power diagrams and report on the design
Investigate    fluid    power            of either a pneumatic or hydraulic multi-actuator
diagrams                                 sequential operation using a minimum of four

                                      • Review fluid power diagrams and report on the design
                                        of either a pneumatic or hydraulic reversible rotary
                                        actuation with speed control in both directions.

                                     •   Identify and describe the features of given items of
OUTCOME 2                                pneumatic and hydraulic equipment.
                                     •   Analyse the performance characteristics of given
Analyse the construction and             pneumatic and hydraulic equipment.
operation of pneumatic and
hydraulic        components,
equipment and plant.

                                     •   Design and draw either a circuit for either a pneumatic
OUTCOME 3                                or hydraulic multi-actuator sequential operation,
                                         including emergency stop functions.
Design      pneumatic      and       •   Design and draw either a hydraulic or pneumatic rotary
hydraulic circuits                       actuation circuit illustrating speed control in both
                                     •   Design and draw either an ‘electro-pneumatic’ or
                                         ‘electro-hydraulic’ circuit arrangement.
                                     •   Design and draw an emergency ‘fail safe’ circuit for
                                         either a pneumatic or hydraulic application.
                                     •   Justify the use of fluid power technology for a given
OUTCOME 4                                industrial application.
                                     •   Describe the technical requirements and commercial
Evaluates            industrial          aspects for a proposed system.
applications of    pneumatics        •   Identify appropriate health safety requirements for the
and hydraulics                           design, installation, maintenance and use of fluid
                                         power equipment.

                                                     Descriptor                                 Achieve
• identify and apply         •   effective judgments have been made
  strategies to find         •   complex problems with more than one variable have been
  appropriate solutions.         explored
                             •   an effective approach to study and research has been

• select/design and apply    •   relevant theories and techniques have been applied.
  appropriate methods/
                             •   a range of methods and techniques have been applied.
                             •   a range of sources of information has been used.
                             •   the selection of methods and techniques/sources has been
                             •   the design of methods/techniques has been justified
                             •   complex information/data has been synthesized and
                             •   appropriate learning methods/techniques have been
• present and                •   the appropriate structure and approach has been used
  communicate the
  appropriate findings       •   coherent, logical development of principles/concepts for
                                 intended audience
                             •   a range of methods of presentation have been used and
                                 technical language has been accurately used
                             •   communication has taken place in familiar and unfamiliar
                             •   the communication is appropriate for familiar and
                                 unfamiliar audiences and appropriate media have been


• use critical reflection    •   conclusions have been arrived at through synthesis of
  to evaluate own work           ideas and have been justified
  and justify valid          •   the validity of results has been evaluated using defined
  conclusions                    criteria
                             •   self-criticism of approach has taken place
                             •   realistic improvements have been proposed against
                                 defined characteristics for success
• take responsibility for    •   autonomy/independence has been demonstrated
  managing             and   •   substantial activities, projects or investigations have been
  organising activities          planned, managed and organised
                             •   activities have been managed
                             •   the unforeseen has been accommodated
                             •   the importance of interdependence has been recognised
                                 and achieved
• demonstrate                •   ideas have been generated and decisions taken
  convergent/lateral/        •   self-evaluation has taken place
  creative thinking          •   convergent and lateral thinking have been applied

                             •   problems have been solved
                             •   innovation and creative thought have been applied
                             •   receptiveness to new ideas is evident
                             •   effective thinking has taken place in unfamiliar contexts
Feedback Comments:

This Assessment brief has been internally verified by ..................................................Date ......................................

Grade Awarded:

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The script has been internally verified by ....................................................... Date .........................................

Throughout the module you should do the following.

   •   Study relevant course notes.

   •   Study the recommended textbooks.

   •   Use the standards publications available in the library.

   •   Make use of suitable web sites.

   •   Make use of journals on fluid power.

   •   Make use of manufacturers catalogues. (RS, NORGREN, REXROTH and so on).

   •   Make use of the standard information pack from the British Fluid Power Association.

In the design parts, you should use the computer software “PneuSim Pro”. The context help
contains diagrams, pictures and symbols.

Your assignment should be structured with headings and subheadings. The work must be your own.
Copies of pages from the internet or from any other source should only be added as reference
material. This should be clearly identified and cross-referenced in your text (e.g. diagram numbers
and appendix numbers).

You may use computer packages such as “word” to produce your work and scan in pictures. You
may do the work in hand writing and paste in pictures and diagrams. What ever method you use,
make sure that the work is identifiable as your own unique style and your research.

Students who address all the issues in full are more likely to obtain a merit or distinction but so long
as the main points are addressed you should obtain a pass grade.

Parts of this assignment may be used as evidence of achievement in the PLC module.

IMPORTANT: Consult with your tutor to ensure that you understand the work to be done before
you commit yourself to any substantial amount of work.


At the end of this assignment seven fluid power systems are described. You will be allocated or
asked to select ONE of them in order to complete this assignment.
                                    ASSIGNMENT DETAILS


You will be allocated one of the seven systems described in the last section. Design a pneumatic or
hydraulic system to the specification given.

   •   The machine must use electric control systems.

   •   Decide whether to use hydraulics or pneumatics. Explain all the points considered in
       arriving at your answer.


At this point you should not design the control system, only the basic circuit.

You need not consider the materials, style or quality of the hardware at this stage.

You should produce your drawing to the ISO standard. All the main control valves must be
solenoid operated.

           •   Using PneusimPro, design and test the circuit if possible (e.g. using manual
               overrides on the valves)

           •   Explain in detail the strategy used to arrive at your design.


You should now consider how control of the system is to be produced and automatic operation
achieved. Remember that electric control must be used. If you have already studied the PLC
module, you may use any of the techniques taught there.

   •   List the sequence of operations and use a suitable graphic aid such as a cycle diagram or
       a step sequence diagram.

   •   Consider whether to use a PLC or a hardwired electric circuit. Discuss the benefits and
       disadvantages of both.

   •   Identify sensors that can be used to make the system work automatically in the correct

   •   Modify your circuit drawing by adding the sensors and/or additional valves.

   •   Construct a separate circuit diagram (within the same project) showing the electric wiring
       diagram and produce a control circuit if require. This will be either a grafset or ladder
       diagram. You may need help and advice on this.

   •   Demonstrate the system working by using the simulation feature.
PART 3                 SAFETY ASPECTS

This section concerns the safe design and operation of the machine. Consider the safety legislation
that is appropriate to this installation.

   •   Identify and discuss the main safety legislation applicable to the installation,
       commissioning operating and maintaining the machine.

   •   Identify the main dangers to look out for when commissioning, operating and
       maintaining this particular machine.

   •   Find out about and explain the reasons for using the following safety features.

         o   Lock out facility.
         o   Automatic cut out.
         o   Emergency stop.
         o   Fail safe. (e.g. safe parking position).
         o   System protection.

   •   Identify which you need to incorporate in your design and give your reasons. You should
       consider things such as :

         o   Prevention of unauthorised tampering.
         o   Possibility of the machine becoming jammed or clogged.
         o   Overheating.
         o   Overpressure.
         o   Fluid levels.
         o   Power overloads

   •   Modify your circuit diagram to include appropriate safety features and add suitable text
       notations if required. This must include an emergency stop


   •   When costing the system the following should be considered. Explain what each means
       and list what would be included in each for this machine.

   o Capital cost.
   o Running cost.


In this section you should consider commissioning and maintenance aspects of the machine.

                   •    Write a brief report outlining the commissioning procedures to be used.
                   •    Write a brief report outlining the maintenance procedures to be used.

A company makes a range of hooks from flat plate for use with climbing gear and safety equipment.
The outline shape fits into a rectangle approximately 100 mm by 150 mm. The last part of the
manufacturing process is to twist the hook by 90o. A single machine is to be custom built to do the

The hooks are manually loaded into a magazine.
The hooks are fed one at a time into a clamp with the hook end sticking out.
A chuck is advances and grips the hook end. This is then twisted.
The clamp releases and the chuck returns pulling the hook out of the clamp and then drops it into a
bin below.
The cycle repeats.

The diagram shows an outline design for a proposed machine to be used for drilling a hole in a
work piece. First the work piece is put in position. Next the guard must be lowered and the work
piece clamped by cylinder C. Three seconds after the guard is lowered, the drilling commences
automatically. The work piece is fed against the drill by cylinder B and this is a double rod type
with the rod fixed at each end. The speed of the feed must be controllable.

A tube is placed on the rests. The start is initiated and the two end cylinders acting at a low pressure
advance and centre the tube. This initiates the clamp cylinders operated at high pressures. When the
clamps are in place, the pressure on the end cylinders is increased to force the ends further and
swage the tube at both ends. The stop is initiated and this makes the end cylinders retract followed
by the release of the clamp cylinders. A rotary actuator then ejects the tube into a box.

When the start is initiated, the furnace door is opened and the trolley advances 1.5 m from its
normal position. The chuck closes on the object in the furnace and grips it. The trolley moves back
3 m and drops the object into a tank underneath. The door must close as soon as possible to reduce
heat loss. The trolley moves forward 1.5 m to its normal position.

The trolley might be moved by two cylinders as shown in order to achieve the 3 positions required.

The door is operated by a motor and lead screw arrangement.

A second start control is to be situated near the furnace for inspection purposes.

A steel company produces large flat bars of various dimensions ranging from 100 mm x 25 mm to
300 mm x 100 mm. The lengths to be cut are to be done in batches with lengths in any multiple of
metres from 1 to 10 m. A single machine is to be custom built to do the following.

The bar comes along a roller track and hits an end stop.
The bar is clamped tightly.
An acetylene cutter head moves to the correct cutting position for the batch.
The cutter cuts the length in a controlled manner and retracts.
The cut bar must be ejected and the process repeated.

The press tool is lowered and raised by one complete revolution of the drive shaft. The operator
brings down the guard and when at the bottom, the lock cylinder automatically engages. The press
cycle automatically starts. First the clutch engages but only if the press tool is in the correct up
position. The press tool descends onto the die and then rises automatically. When fully raised, the
clutch must be disengaged and the guard lock is disengaged. The lock cylinder must not open unless
the press tool is fully raised and stopped at this position. You must select and arrange appropriate
sensors as required.02

The machine is based around a pillar drill design. The purpose is to spin rivet two adjacent rivets
one at a time. The machine must not operate unless the guard is down and the start switch pressed.
The cycle is as follows.

Lower guard
Lower riveting head.
Retract riveting head.
Lower riveting head.
Retract riveting head.
Return index to normal position.

You must select and arrange appropriate sensors to make the cycle work.

Identical boxes are dropped onto the end of a conveyor from a gravity chute and travel along to a
junction where they may carry on to processing station A or be diverted to station B. Drive motor C
operates the first conveyor. Drive motors A and B operate the conveyors to stations A and B. If the
boxes pile up at A because they cannot be removed quickly enough, the divert cylinder is operated
automatically and the boxes are sent down a second conveyor to station B. If station A clears, boxes
are not diverted.

If both stations become clogged at the same time, the stop cylinder is activated to prevent further
boxes coming out of the gravity chute and the drive motor C is stopped. If either station clears, this
process is reversed.

You will need to devise a sensor system to detect a pile up at each station. This will occur when a
box comes to rest against the box in front of it at a given point on the conveyor.

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