DESIGN AND FABRICATION OF A PRINTING /BLOCK MACHINE

(Mechanical Engineering)

DESIGN AND FABRICATION OF A PRINTING /BLOCK MACHINE

ABSTRACT

Parameters on which clear prints depends were comprehensively investigated.  The study revealed that clear print depends on the impressed pressure the working temperature and the gold foil print paper life expectancy.

Also studies were he manner of dependence of these parameters on prints impressed  on sheets of varied thickness.  The results of these investigation were  utizlied in the design and fabrication of an operational manual printing machine using gold foil   sheet depositor clear prints were impressed on papers during the new machine’s operation.

LIST OF FIGURES

Description

Figure 1 sketch of alternative A

Figure 2. Sketch of alternative B.

Figure 3 sketch of alternative C

Figure 4 isomeric view of hot plate square housing

Figure 5 isometric view of type holder

Figure 6 &7 load and free body diagram of crank are (Handle) and rod.

LIST OF SYMBOLS

A – Area

A – Acceleration

D – Maximum shaft diameter

d-      minimum  shaft diameter

e-        efficiency

k – Thermal conductivity

c – Heat capacity

x – The pressure transmissibility of lever system (press x  1/duration )

t – Time

l – Length of shaft

m – Mass

m – Maximum bearding moment

p - Electric power

q – Quantity of heat

TABLE OF CONTENTS

CHAPTER ONE

1.1              introduction                                                               

1.2              literature review and data collection                          

1.3              experimental determination of pressure for prating               

1.4               design specification                                      

CHAPTER TWO

2.1              Design solutions                                                         

2.2              Alternative A press foot printer                                             

2.3              Alternative  B; crank arm  (handle )                          

2.4              Alternative  C; automatic (motorized) printer                       

2.5              Comparison of alternative and choice                                   

CHAPTER THREE

3.1              Design selection and analysis of parts of chosen alternative

3.2              Theory of  design/  design calculation                                   

3.3              The  design of the shaft (Hollow)                                          

CHAPTER FOUR               

4.1              construction of prototype                                                                  

4.2              general                                                                                    

4.3              material selection                                                                   

4.4              sequence of construction and assembly                                 

CHAPTER FIVE

5.1              Testing of prototype (test – run)                                            

5.2              Evaluation of machine efficiency                              

5.3              Operator’s manual                                                                  

5.4              Costing  (cost analysis)                                                          

5.5              Problems Encounter                                                   

5.6              Conclusion                                                                             

5.7             

Reference

Recommendation                                                                               

 

CHAPTER ONE

 

1.1       INTRODUCTION

            Nigeria in recent times lays strong emphasis on mass literacy  and indigenous technology.  Printed matters are indispensable materials in mass literacy campaign  and the trend towards indigenous technology imposes a  severe  clamp down on imputed engineering including printing block machinery.  Thus the situation is  such that make  the acquisition of printing machinery from outside our boards extremely difficult.

            Therefore to lessen the economic strain on  the mass literacy campaign local  production of  printing machinery is apparently imperative.  It is this fact that rendered integrative to the conception and realization of this low cost but efficient printing machine based entirely on local technology and resources.

            The present machine is very useful in the printing of many items like paper backs cards etc. its design and fabrication is expected to motivate and advance the design and fabrication of other machines destined for similar purpose and based on indigenous technology and resources.

1.2       LITERATURE REVIEW AND DATA COLLECTION

            There were no available books in printing in both the state and school libraries that actively dealt with printing technology. The only books available were those  on the  history of ‘Types’ and trade journals advertising products of foreign companies which were fund to be of little or no relevance.

            However a visit to the government printing press gave us an opportunity to study the ‘types’ available and the basic operations of  the giant printing  (Blocking) machine with respect to the ‘Types’ from there we  were able to establish;

(a)                The effect of temperature on the amount of gold deposited from sheet (sharpness of print )

(b)               The  effect of life time on the gold foil sheet depositor.

(c)                The effect of pressure on the amount  of gold  deposited from sheet  (sharpness of print )

(d)               The  effect of size of ‘types’ on the sharpness  of print  (amount of gold  deposited )

Definition:

Types : These are the characters or alphabets that forms the  letters.

Print :- This is  the mark or impression produced on paper due to the types. Gold foil  sheet depositor :- is a thin rectangular  cellophane sheet coated with gold compound.

1.3              EXPERIMENTAL DETERMINATION OF PRESSURE FOR PRINTING.

The print there must be impact force between two  surfaces on e of which contains the ‘type’ and the other the paper on which print will be made. The force produces the necessary pressure for printing.

         Consider alternative ‘B’ of the possible design solution.  Impact force  is due to the acceleration of mass of moveable plate and rail against the stationary letter box located on the element box.  The pressure for printing is  impact force for a  constant                                                                                                              surface area

Impact surface area the pressure varies with variation in the impact force.  Similarly the impact force varies with the mass and acceleration.  But  the  mass is constant and equal to mass of rail plus mass of moveable plate hence only the acceleration varies. Therefore in this experiment effort has been made to determine.

(a)          The  pressure required  to print clearly on thin cellophane sheet without perforating it.

(b)         The pressure required to  print clearly on paper of average thickness without perforating it

(c)          The  pressure required to print on cardboard sheet such that very sharp prints are obtained  by varying the input acceleration

Materials: very light cellophane paper, paper back of higher education exercise book ceiling sheet (card board)  silver sheets,

Apparatus: Election- speed printer machine

Definition: The electronic speed printer machine is a motorized electronic motor.  It  has a device for varying the acceleration the current input  can varied hence the heat generate and therefore the temperature varied.

Method: the acceleration is varied keeping the temperature and surface area of impact constant.  Already the striking mass is constant.  The following values show the accelerations at which sharpest prints were obtained without perforation of the materials after several trial.  The corresponding forces and pressure are also shown.

TABLE 1

Material

Accel. For sharpest print without perforation

Mass (m)

Force (ma)

Pressure (ma/a)

Cellophane paper

0.07mls 2

35kg

2.45N

2.45

0.0972 = 25.24 n/m2

Paper back of higher education note book

0.76 mls2

35kg

26.6N

26.6 =  273.N/M2

0.0972

 

 

Ceiling sheet

Cardboard

2.3 mls2

35kg

80.8n

80.8       = 831 N/m2

0.0.972

 

·               operating temperature 1550c  (fixed)

·               0.0972 = area of foolscap sheet (fixed)

for the heating coil, the heat dissipated given by H. = 12 Rt where 1  = current passing in ampere R = resistance of coil in ohms and t = duration time in seconds. It varies directly with  temperature which is the measurement of heat hence the determination of:

TABLE 11

EFFECT F TEMP. ON SHARPNESS OF PRINT

Temp

(0 c)

Cellophane paper

Paper back of higher Edu. Book

Ceiling sheet cardboard

Acceleration (m/s2)

Pressure (N/m2

25

No print

No print

 No print

0.07

25.2

50

Slight deposit

No print

No print

0.07

25.2

155

Sharp print

No  print

No print

0.07

25.2

200

 

 

No  print

0.07

25.2

250

Shrinks

Non – clear print

No print slight deposit

0.07

25.2

25

Slight deposit

No print

No print

0.76

273

50

Clear print

Slight print

No print

0.76

273

155

Perforation

 Sharp print

No print

0.76

273

200

Burns / shrins

Slight groove

Slight deposit

 

273

250

Increased burns

Deeper  grooves

Non- clear print

0.76

273

25

Fairly clear print

Slight deposit

Slight deposit

2.3

831.2

50

Perforation

Clear print

Non-clear print

2.3

831.2

 

155

Burns/ shrinks

Sharp print with very deep groove

Sharp print

2.3

831.2

200

Increased burns

Perforation  begins

Grooving  begins

2.3

831.2

250

Increased burns

Deeper perforations

Deeper groove

2.3

831.2

 

OBSERVATION:

From tables 1 and 11 it can be observed that

(a)                The sharpness of  print varies directly  with the acceleration and hence the operating pressure.

(b)               The sharpness of print varies directly with temp.

(c)                No matter how high the pressure applied at room temp.250c) a sharp print can never be obtained before and even after grooving and consequent perforation occurs.

(d)               By increasing acceleration and decreasing tem. Or vice- versa sharpness of prints can be altered provided the temp. Variation does not require a fall below 1550c.

CONCLUSION:

Sharpness of print depends on pressure and on temp (from about 1500c upwards).

(a)                EFFECT OF LIFE TIME ON GOLDEN FOIL DEPOSITION

Gold foil sheet as already defined is a very thin rectangular cellophane sheet coated with golden compound chemical such that temperature and pressure can be regulate its deposition on paper. Form the time of production (coating of gold on  cellophane) the coherency of gold deposit decreases with time until a times when the layers of the compound starts peeling off from the sheet by itself.  Hence sharpness of print depends on  life time of coating. This  fact was established after observing different life  golden sheets used under same temperature and pressure.

(b)        THE EFFECT OF SIZE OF TYPES ON THE SHARPNESS OF PRINT.

Since pressure = force / Area the same force applied ‘types’ having smaller surface area exerts greater pressure in direct proportion to the ratios of  their surface area.

1.4       DESIGN SPECIFICATION

            The printing (blocking) machine to be designed must be able to:

1.4.1        produce sharp print on paper from gold coated sheet

1.4.2        require small effort for operation

1.4.3        resist failure of excessive effort should be applied.

1.4.4        Be easily  operated by anybody

1.4.5        Produce as many per unit time as possible.

1.4.6        Must be relatively cheap in every respect

1.4.7        Should be compact and portable

1.4.8        Should nut be too heavy – can easily be  moved from one location to another

1.4.9        Position of operator  in use should be convenient not tiring

1.4.10      Should be durable

1.4.11     should  have replaceable parts – using bolts, screws and other forms of assembly rather than welding.  Also using components whose  forming / manufacturing process is less complex so the user can easily replace damaged parts.

1.4.12     Manufacture ability – can be manufactured  within the limits of  available materials and processes in the school workshop and neighboring establishments.

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