EDITED:
JUNE, 1980
DEDICATION TO:
My beloved parents Mr. and Mrs. MA’AJI B. NEYU for their tender love and care
THE DESIGN AND MANUFACTURE OF A WORK HOLDER FOR THE SENSITIVE DRILLING MACHINE
BY
C. M. ZONKWA. O.N.D(MECHANICAL ENGINEERING) REG:KPT/CST/75/288
A PROJECT SUBMITTED AS PART OF THE REQUIREMENTS FOR THE AWARD OF THE HIGHER NATIONAL DIPLOMA IN MECHANICAL ENGINEERING IN THE COLLEGE OF SCIENCE AND TECHNOLOGY KADUNA POLYTECHNICJUNE, 1980
DEDICATION TO:
My beloved parents Mr. and Mrs. MA’AJI B. NEYU for their tender love and care
ACKNOWLEDGEMENT
I owe deep gratitude to so many people for their help toward the completion of this work. In particular: Messrs F.S.N.ORUCHE (Principal Lecturer) and G.D. OLIVER (Senior Lecturer) for allowing me to carry out the project without rigid supervision and for their constructive criticisms, which stimulated my own initiative. Their lectures were also a source of inspiration to me.
Mr. Anthony Afolayan (the Plan/Maintenance Manager) of Kaduna Textiles Limited for - his un-tiring support throughout my Industrial Training period where this project was conceived.
ABSTRACT
The difficulty encountered in holding awkwardly shaped work-pieces in vices, compelled most operators to hold the work-piece with their hand during the drilling operation. Similar forces experienced in milling and shaping are also to be found in drilling causing a large number of drills to break. Therefore, this necessitates the design of a universal work clamp to form an integral part of the Drilling Machine, with a view of producing a more efficient condition. From experimental work with the drill dynamometer, the material that is most likely to cause some difficulty when drilling is the High Carbon Steel therefore, the limiting condition used in the design are those for High Carbon Steel. Detail drawings of the design are presented along with an assemble drawing. Further the clamp was manufacture and tested with satisfactory results and reliability.
CONTENTS
CHAPTER PAGE
ACKNOWLEDGE ***** * ***
ABSTRACT...........
INTRODUCTION.........
1. The sensitive drilling machine
2. Measurement of forces
3. Design of Work Holder
It. Detail shape and Dimensions
5. Commissioning and Testing of Equipment
6. Conclusion....
INTRODUCTION
In the production department of most industries, the machine shop generally, is the most extensively used for the manipulation of solid and sheet metal into different components.
For this purpose the shop is equipped with various machines or group of machines necessary for such operations, and the sensitive drilling machine is to be found in the fitting section. This widely use machine is capable of drilling holes in the range of lmm - 15mm. But yet on the sensitive drilling machine one vital problem is being over looked.
No one thinks of holding a work-piece by hand on a shaping or milling machine, yet similar cutting forces are experienced on the sensitive drilling machine. The rate of accidents on the sensitive drilling machine is alarming, most small drills end their services here and many operators lose or wound their eyes here due to flying particles of drills and chips when the drill break.
The machines are rarely to be blame. It is a common practice to find students even a qualified fitter/machinist operating the sensitive drilling machine and holding the work-piece with their hand.
If the work picks up and torn from the grasps at 360rev/mm, the time available for hand removal is about one sixth of a second before it comes round to strike.
Since human re-action times are of the order of two-fifths of a second the odd are in favour of an accident. Since these accidents are not confined to trainees in Colleges but also to those working in industries, a permanent fixture for holding down Work-Pieces is suggested. This will minimise the accidents experience by operators.
CHAPTER ONE
THE SENSITIVE DRILLING MACHINE
These machines are usually bench mounted. They are of small capacity, usually for drilling holes of small sizes from lmm to 15mm diameter. Because of the delicacy of the drill and work the machine feed is only manually operated. The rotational movements of the drill are provided by means of accurately made spindle mounted in suitably designed bearings. The spindle has torsional and flexural rigidity and stiffness to suit the applied forces, It has to receive and transmit to the tool required force to maintain the cutting action.
The drive to the spindle does not normally move down with the feed. So provision is made for downward movement by means of a rack and pinion. The feeds lever is attached outside the spindle housing to the shaft of the pinion thus the operator can move the sleeve and spindle downwards or up-wards,
The column supports all the parts of the machine itself carried by the base which secures it to the bench. The adjustments that are available are as follows:-
CHAPTER 5
COMMISSIONING
In commissioning this equipment, the drilling machine head had to be stripped down so as to facilitate the
slipping of the equipment into position.
This involves the following operations
(1) Disconnection of electrical cable leading to the machine motor.
(2) Removal of motor
(3) Removal of the spindle bracket and
(4) Removal of the main bracket.
After slipping of the work holder the drilling machine was re-assemble.
TESTING OF EQUIPMENT
During testing, it was found that the equipment provided positive clamping to the machine table, not only of even-shaped objects but also of odd-shaped ones that cannot be readily, held in a vice such as carburetors, tapered components etc, This positive clamping of jobs makes the axis of the finished hole truer to that of the drilling machine spindle than could be obtained using the vice and hands.
In addition the work holder provides a more versatile clamping, because it can be swung or raised to allow high work to be drilled. Also it allows each operator to work independently of another, there by saving man-hours,
This serious unnecessary expensed that most employer encounter as accidents and bad workmanship, that .are frequently experienced on the sensitive drilling machine the machine which are rarely to blame, has been a matter of concern. This work holder was conceived so as to eliminate accidents and elevate the accuracy of the finished drilled holes. The sensitive drilling Machine because of light and delicate control makes it suitable for use where small holes are to be drilled. The machine is manually feed in that the progress of the drill can be felt, so that if the drilling operation is impeded pressure can be released.
Operators are tempted to hold work pieces with the hand during the feeding of the drill and it is not always convenient for clamping, Complicated shape components readily.
This equipment provides a simpler way of positive clamping for all type of work pieces than could be obtained with vice and hand.
On testing, it was found beside positively holding the components, it provides a true finished axis of hole to the machine spindle. This true holes axis with the job clamped on the machine table, complicated shape components can be tapped without necessary removing them from the machine table.
In addition the equipment provide minimum tendency of the drilling machines abuse by operators. ,
In manufacturing of this equipment, the original design had to be deviated slightly due to unavailability of the require size of material in the market. This not whit standing it is contention that the basic assumption governing the design of this work holder have been proved to be practicable.
As the manufactured equipment was being fixed on the machine, the drilling machine head had to be stripped down. This was necessary because there was no provision made for the incorpo¬ration of this equipment on an already assemble machine to its column.
However to avoid this stripping of machine head, the main arm of the design equipment could be made into two half’s by splitting and provision made to bring the two parts together with the aid of a bolt.
In the case of a new machine not yet assemble however splitting of the main arm will not be necessary as it could just be slipped into position on the column during assembly.
For mass production drop forging of the main arm is more appropriate.
REFERENCE
1. LECTURE NOTES
Engineering Design (1978/79 session) G.R. Oliver / I. Abdulkadir
2. Lecture Notes
Applied Mechanics/Mechanics of Machines
(1977/78), (1978 - 79 session) F.S.N. Oruche,
3. Design Engineering: Inventivenes Analysis and aftMsion Making By J.R. Dixon Publisher. McGraw 7 Hill NewYork.
4. Mechanics of Solids and Structures PP Benhams and Warnock. Publisher, Pitman
5. Twist Drills. Firth Brown Tools Ltd.
ABSTRACT
The difficulty encountered in holding awkwardly shaped work-pieces in vices, compelled most operators to hold the work-piece with their hand during the drilling operation. Similar forces experienced in milling and shaping are also to be found in drilling causing a large number of drills to break. Therefore, this necessitates the design of a universal work clamp to form an integral part of the Drilling Machine, with a view of producing a more efficient condition. From experimental work with the drill dynamometer, the material that is most likely to cause some difficulty when drilling is the High Carbon Steel therefore, the limiting condition used in the design are those for High Carbon Steel. Detail drawings of the design are presented along with an assemble drawing. Further the clamp was manufacture and tested with satisfactory results and reliability.
CHAPTER PAGE
ACKNOWLEDGE ***** * ***
ABSTRACT...........
INTRODUCTION.........
1. The sensitive drilling machine
2. Measurement of forces
3. Design of Work Holder
It. Detail shape and Dimensions
5. Commissioning and Testing of Equipment
6. Conclusion....
INTRODUCTION
In the production department of most industries, the machine shop generally, is the most extensively used for the manipulation of solid and sheet metal into different components.
For this purpose the shop is equipped with various machines or group of machines necessary for such operations, and the sensitive drilling machine is to be found in the fitting section. This widely use machine is capable of drilling holes in the range of lmm - 15mm. But yet on the sensitive drilling machine one vital problem is being over looked.
No one thinks of holding a work-piece by hand on a shaping or milling machine, yet similar cutting forces are experienced on the sensitive drilling machine. The rate of accidents on the sensitive drilling machine is alarming, most small drills end their services here and many operators lose or wound their eyes here due to flying particles of drills and chips when the drill break.
The machines are rarely to be blame. It is a common practice to find students even a qualified fitter/machinist operating the sensitive drilling machine and holding the work-piece with their hand.
If the work picks up and torn from the grasps at 360rev/mm, the time available for hand removal is about one sixth of a second before it comes round to strike.
Since human re-action times are of the order of two-fifths of a second the odd are in favour of an accident. Since these accidents are not confined to trainees in Colleges but also to those working in industries, a permanent fixture for holding down Work-Pieces is suggested. This will minimise the accidents experience by operators.
CHAPTER ONE
THE SENSITIVE DRILLING MACHINE
These machines are usually bench mounted. They are of small capacity, usually for drilling holes of small sizes from lmm to 15mm diameter. Because of the delicacy of the drill and work the machine feed is only manually operated. The rotational movements of the drill are provided by means of accurately made spindle mounted in suitably designed bearings. The spindle has torsional and flexural rigidity and stiffness to suit the applied forces, It has to receive and transmit to the tool required force to maintain the cutting action.
The drive to the spindle does not normally move down with the feed. So provision is made for downward movement by means of a rack and pinion. The feeds lever is attached outside the spindle housing to the shaft of the pinion thus the operator can move the sleeve and spindle downwards or up-wards,
The column supports all the parts of the machine itself carried by the base which secures it to the bench. The adjustments that are available are as follows:-
CHAPTER 5
COMMISSIONING
In commissioning this equipment, the drilling machine head had to be stripped down so as to facilitate the
slipping of the equipment into position.
This involves the following operations
(1) Disconnection of electrical cable leading to the machine motor.
(2) Removal of motor
(3) Removal of the spindle bracket and
(4) Removal of the main bracket.
After slipping of the work holder the drilling machine was re-assemble.
TESTING OF EQUIPMENT
During testing, it was found that the equipment provided positive clamping to the machine table, not only of even-shaped objects but also of odd-shaped ones that cannot be readily, held in a vice such as carburetors, tapered components etc, This positive clamping of jobs makes the axis of the finished hole truer to that of the drilling machine spindle than could be obtained using the vice and hands.
In addition the work holder provides a more versatile clamping, because it can be swung or raised to allow high work to be drilled. Also it allows each operator to work independently of another, there by saving man-hours,
CONCLUSION
This serious unnecessary expensed that most employer encounter as accidents and bad workmanship, that .are frequently experienced on the sensitive drilling machine the machine which are rarely to blame, has been a matter of concern. This work holder was conceived so as to eliminate accidents and elevate the accuracy of the finished drilled holes. The sensitive drilling Machine because of light and delicate control makes it suitable for use where small holes are to be drilled. The machine is manually feed in that the progress of the drill can be felt, so that if the drilling operation is impeded pressure can be released.
Operators are tempted to hold work pieces with the hand during the feeding of the drill and it is not always convenient for clamping, Complicated shape components readily.
This equipment provides a simpler way of positive clamping for all type of work pieces than could be obtained with vice and hand.
On testing, it was found beside positively holding the components, it provides a true finished axis of hole to the machine spindle. This true holes axis with the job clamped on the machine table, complicated shape components can be tapped without necessary removing them from the machine table.
In addition the equipment provide minimum tendency of the drilling machines abuse by operators. ,
In manufacturing of this equipment, the original design had to be deviated slightly due to unavailability of the require size of material in the market. This not whit standing it is contention that the basic assumption governing the design of this work holder have been proved to be practicable.
As the manufactured equipment was being fixed on the machine, the drilling machine head had to be stripped down. This was necessary because there was no provision made for the incorpo¬ration of this equipment on an already assemble machine to its column.
However to avoid this stripping of machine head, the main arm of the design equipment could be made into two half’s by splitting and provision made to bring the two parts together with the aid of a bolt.
In the case of a new machine not yet assemble however splitting of the main arm will not be necessary as it could just be slipped into position on the column during assembly.
For mass production drop forging of the main arm is more appropriate.
FULL DETAIL VISIT http://www.docs.google.com/
REFERENCE
1. LECTURE NOTES
Engineering Design (1978/79 session) G.R. Oliver / I. Abdulkadir
2. Lecture Notes
Applied Mechanics/Mechanics of Machines
(1977/78), (1978 - 79 session) F.S.N. Oruche,
3. Design Engineering: Inventivenes Analysis and aftMsion Making By J.R. Dixon Publisher. McGraw 7 Hill NewYork.
4. Mechanics of Solids and Structures PP Benhams and Warnock. Publisher, Pitman
5. Twist Drills. Firth Brown Tools Ltd.
LIBRARY: http://www.kadunapolytechnic.edu.ng/coe.asp/
