03-09-2014, 03:38 PM
lathe machine
[attachment=67590]
INTRODUCTION
What is a lathe machine?
A lathe is a machine tool that rotates the work piece against a tool. The spindle is the part of the lathe that rotates. It is driven by an electric motor through a system of belt drives and gear trains. Its rotational speed is controlled by varying the geometry of the drive train.
Lathes were developed as early as the 15th century and were known as "bow" lathes. The operator rotated the work piece by drawing a bow back and forth, either by hand or with the use of a foot treadle.
Next came Bosons lathe in 1568, which was driven by a cord passing over a pulley above the machine. This in turn drove two other pulleys on the same shaft which rotated the work piece and a crude, wooden lead screw, which in turn allowed the operator to remove metal from the piece being machined. The screw cutting lathe originates in the 17th century. Development and advancements have continued and today we have sophisticated computerized controlled lathes.
Lathes have allowed man to reshape, machine and manufacture many precision cylindrical components made of various types of metal, wood, plastics, and other material. Without the lathe, man would still be trying to produce cylindrical components
Tailstock
The tailstock can be used to support the end of the work piece with a center, or to hold tools for drilling, reaming, threading, or cutting tapers. It can be adjusted in position along the ways to accommodate different length work pieces. The tailstock barrel can be fed along the axis of rotation with the tailstock hand wheel.
Carriage
The Carriage controls and supports the cutting tool. It consists of:
Saddle that slides along the ways.
An apron that controls the feed mechanisms.
A tool compound that adjusts to permit angular tool movement.
Bed
The bed supports all major components of the lathe. Beds have a large mass and are built rigidly, usually manufactured from gray or nodular cast iron.
Feed rod and lead screw
The feed rod is powered by a set of gears through the headstock. The rod rotates during the lathe operation and provides movement to the carriage and the cross-slide by means of gears, friction clutch and a keyway along the length of the rod.
The lead screw will cause the apron and cutting tool to advance quickly. This is used for cutting threads, and for moving the tool quickly.
The feed rod will move the apron and cutting tool slowly forward. This is largely used for most of the turning operations.
Lathe types
There are a number of different lathe designs, and some of the most popular are discussed here.
Engine lathe
It is the basic, simplest and the most versatile lathe. This machine tool is manually operated that is why it requires skilled operators. Suitable for low and medium production and for repair works.
Turret lathes
These machines are capable of carrying out multiple cutting operations on the same work piece. Several cutting tools are mounted on a tetra-, penta-, or hexagonal turret, which replaces the tailstock. These tools can be rapidly brought into action against the work piece one by one by indexing the turret.
Computer-numerical control lathes (CNC lathes)
Computer-controlled (numerically controlled, NC, CNC) lathes incorporate a computer system to control the movements of machine components by directly inserted coded instructions in the form of numerical data. A CNC lathe is especially useful in contour turning operations and precise machining. A CNC lathe is essentially a turret lathe. The major advantage of these machines is in their versatility - to adjust the CNC lathe for a different part to be machined requires a simple change in the computer program and, in some cases, a new set of cutting tools.
Special purpose lathes
These lathe machines are used for applications such as railroad wheels, gun barrel and rolling mill rolls. The size of the work piece is usually large in these machines.
Tracer lathe
These lathes have special attachments that are capable of turning parts with various contours. They are also known as duplicating or contouring lathes. The cutting tool follows the path that duplicates the contour of the template.
Automatic lathes
In fully automatic lathes, parts are fed and removed automatically, whereas in semiautomatic lathes these functions are performed by the operator. These machines may have horizontal or vertical spindle and are suitable for medium to high volume production.
4.Machining Operations Usually Done In Centre Lathes
The machining operations generally carried out in centre lathes are:
• Facing
• Centering
• Rough and finish turning
• Chamfering, shouldering, grooving, recessing etc
• Axial drilling and reaming by holding the cutting tool in the tailstock barrel
• Taper turning by
offsetting the tailstock
swiveling the compound slide
using form tool with taper over short length
using taper turning attachment if available
Combining longitudinal feed and cross feed, if feasible.
• Boring (internal turning); straight and taper
• Forming; external and internal
• Cutting helical threads; external and internal
• Parting off
• Knurling
In addition to the aforesaid regular machining operations, some more operations are also occasionally done, if desired, in centre lathes by mounting suitable attachments available in the market, such as,
• Grinding, both external and internal by mounting a grinding attachment on the saddle
• Copying (profiles) by using hydraulic copying attachment
• Machining long and large threads for lead screws, power-screws, worms etc. by using thread milling attachment.
CHAPTER 2
PROBLEM IDENTIFICATION
In an ordinary lathe during the mass production, sequence of operations cannot be handled; in spite of this the production time is increased. For avoiding this delay, we implement the attachments in lathe to minimize the time and cost. These attachments are simple to handle and made neatly. So, the accuracy and quality has been achieved with the special attachments in the lathe.
CHAPTER 3
SCOPE OF THE PROJECT
In recent years new fabrication techniques have been developed to satisfy the technological demands. Attachments are used in various fields and machines depending upon the needs to be fulfilled and mode of operation. An attachment eliminates the purchasing of a new machine which serves the same purpose and also it is helped for the mass production.
For example if there is an order for a machine both cylindrical and flat keyways we need to go for two different machines which would occupy space and hence in order to reduce the space. We go for such attachment by implementing an attachment to a unit the capacity of the machine can be increased which is very economical.
CHAPTER 4
LITERATURE SURVEY
4.1 DRILLING IN THE LATHE
A lathe may be used as a horizontal drilling machine and both sensitive and large drill presses are really developments of the lathe. The drill press is a vertical lathe without any provision for mounting turning tools. The use of a horizontal table on a drill press makes it more suitable for handling large and heavy work as the weight of the pieces drilled serve to hold them in place on the table. A lathe can be used in drilling; only it is more difficult to support the work when it is bulky or heavy. The simplest method of drilling is to place the drill in the lathe chuck and hold the piece to be drilled by hand against the drill pad held in the tail stock, using the tail stock hand wheel to feed the work against the drill. In this case, the drill turns as it does in a drilling machine and the work remains stationary. The lathe chuck or face plate is often employed to hold the work to be drilled as at Fig. 4.1 while the drill chuck is supported by the tail stock. The method of supporting a piece when a long hole is to be drilled by using a center rest or back rest clamped to the ways of the lathe is clearly shown at Fig. 4.1. The use of a centering tool which is held in the tool post is outlined in this view.
4.2 GLOBE MILLING AND DIVIDING ATTACHMENTS
Manufactured by Globe Products Mfg. Co. of 3380 Robertson Blvd., Ashley, Los Angeles, California the Globe lathe milling attachment had a principle of operation like that of a "Lincoln" miller where the work piece, instead of moving, was clamped to a table and the cutter head made to traverse across it. Patented during the early 1940s (2,386,461 by Paul Hellman) it very heavily-built with a base machined ready to fit a variety of popular lathes - including Atlas and Craftsman 9", 10" and 12"; Clausing and Logan 10", Sheldon 10", 11" and 12"; South Bend 16", Workshop 9", Model R and Heavy Ten and the Lodge & Shipley 18". Other fittings could be supplied to order and the Company boasted of Government contracts to provide specially equipped and develop units for a variety of novel purposes. Although not mentioned in the advertising literature, the unit may have been made in more than one size and models marked 90-91 50-51 have been discovered.
CHAPTER 5
CONCLUSION
Thereby reducing the cost of the machine can be achieved through milling attachment to a lathe in a reliable and timely manner.
The main part of any milling attachment is a good, heavy angle plate. It can be used by itself, to hold jobs line boring or even milling in cases where vertical is the advantage of building this attachment is its low because the compound rest is normally not utilized attachment, It is used as part of the home built project the vertical feed portion and is ready with its ball crank.
During this task, we have discussed the various types of lathes, accessories, uses, and some of the lathe operations that the machinist will encounter in the machine shop. With proper application, this information will assist those dealing with lathe operations or the machinists that are performing these functions in the metalworking field. In task two and three of this lesson, grinding, milling attachments, and thread forms will be discussed.
[attachment=67590]
INTRODUCTION
What is a lathe machine?
A lathe is a machine tool that rotates the work piece against a tool. The spindle is the part of the lathe that rotates. It is driven by an electric motor through a system of belt drives and gear trains. Its rotational speed is controlled by varying the geometry of the drive train.
Lathes were developed as early as the 15th century and were known as "bow" lathes. The operator rotated the work piece by drawing a bow back and forth, either by hand or with the use of a foot treadle.
Next came Bosons lathe in 1568, which was driven by a cord passing over a pulley above the machine. This in turn drove two other pulleys on the same shaft which rotated the work piece and a crude, wooden lead screw, which in turn allowed the operator to remove metal from the piece being machined. The screw cutting lathe originates in the 17th century. Development and advancements have continued and today we have sophisticated computerized controlled lathes.
Lathes have allowed man to reshape, machine and manufacture many precision cylindrical components made of various types of metal, wood, plastics, and other material. Without the lathe, man would still be trying to produce cylindrical components
Tailstock
The tailstock can be used to support the end of the work piece with a center, or to hold tools for drilling, reaming, threading, or cutting tapers. It can be adjusted in position along the ways to accommodate different length work pieces. The tailstock barrel can be fed along the axis of rotation with the tailstock hand wheel.
Carriage
The Carriage controls and supports the cutting tool. It consists of:
Saddle that slides along the ways.
An apron that controls the feed mechanisms.
A tool compound that adjusts to permit angular tool movement.
Bed
The bed supports all major components of the lathe. Beds have a large mass and are built rigidly, usually manufactured from gray or nodular cast iron.
Feed rod and lead screw
The feed rod is powered by a set of gears through the headstock. The rod rotates during the lathe operation and provides movement to the carriage and the cross-slide by means of gears, friction clutch and a keyway along the length of the rod.
The lead screw will cause the apron and cutting tool to advance quickly. This is used for cutting threads, and for moving the tool quickly.
The feed rod will move the apron and cutting tool slowly forward. This is largely used for most of the turning operations.
Lathe types
There are a number of different lathe designs, and some of the most popular are discussed here.
Engine lathe
It is the basic, simplest and the most versatile lathe. This machine tool is manually operated that is why it requires skilled operators. Suitable for low and medium production and for repair works.
Turret lathes
These machines are capable of carrying out multiple cutting operations on the same work piece. Several cutting tools are mounted on a tetra-, penta-, or hexagonal turret, which replaces the tailstock. These tools can be rapidly brought into action against the work piece one by one by indexing the turret.
Computer-numerical control lathes (CNC lathes)
Computer-controlled (numerically controlled, NC, CNC) lathes incorporate a computer system to control the movements of machine components by directly inserted coded instructions in the form of numerical data. A CNC lathe is especially useful in contour turning operations and precise machining. A CNC lathe is essentially a turret lathe. The major advantage of these machines is in their versatility - to adjust the CNC lathe for a different part to be machined requires a simple change in the computer program and, in some cases, a new set of cutting tools.
Special purpose lathes
These lathe machines are used for applications such as railroad wheels, gun barrel and rolling mill rolls. The size of the work piece is usually large in these machines.
Tracer lathe
These lathes have special attachments that are capable of turning parts with various contours. They are also known as duplicating or contouring lathes. The cutting tool follows the path that duplicates the contour of the template.
Automatic lathes
In fully automatic lathes, parts are fed and removed automatically, whereas in semiautomatic lathes these functions are performed by the operator. These machines may have horizontal or vertical spindle and are suitable for medium to high volume production.
4.Machining Operations Usually Done In Centre Lathes
The machining operations generally carried out in centre lathes are:
• Facing
• Centering
• Rough and finish turning
• Chamfering, shouldering, grooving, recessing etc
• Axial drilling and reaming by holding the cutting tool in the tailstock barrel
• Taper turning by
offsetting the tailstock
swiveling the compound slide
using form tool with taper over short length
using taper turning attachment if available
Combining longitudinal feed and cross feed, if feasible.
• Boring (internal turning); straight and taper
• Forming; external and internal
• Cutting helical threads; external and internal
• Parting off
• Knurling
In addition to the aforesaid regular machining operations, some more operations are also occasionally done, if desired, in centre lathes by mounting suitable attachments available in the market, such as,
• Grinding, both external and internal by mounting a grinding attachment on the saddle
• Copying (profiles) by using hydraulic copying attachment
• Machining long and large threads for lead screws, power-screws, worms etc. by using thread milling attachment.
CHAPTER 2
PROBLEM IDENTIFICATION
In an ordinary lathe during the mass production, sequence of operations cannot be handled; in spite of this the production time is increased. For avoiding this delay, we implement the attachments in lathe to minimize the time and cost. These attachments are simple to handle and made neatly. So, the accuracy and quality has been achieved with the special attachments in the lathe.
CHAPTER 3
SCOPE OF THE PROJECT
In recent years new fabrication techniques have been developed to satisfy the technological demands. Attachments are used in various fields and machines depending upon the needs to be fulfilled and mode of operation. An attachment eliminates the purchasing of a new machine which serves the same purpose and also it is helped for the mass production.
For example if there is an order for a machine both cylindrical and flat keyways we need to go for two different machines which would occupy space and hence in order to reduce the space. We go for such attachment by implementing an attachment to a unit the capacity of the machine can be increased which is very economical.
CHAPTER 4
LITERATURE SURVEY
4.1 DRILLING IN THE LATHE
A lathe may be used as a horizontal drilling machine and both sensitive and large drill presses are really developments of the lathe. The drill press is a vertical lathe without any provision for mounting turning tools. The use of a horizontal table on a drill press makes it more suitable for handling large and heavy work as the weight of the pieces drilled serve to hold them in place on the table. A lathe can be used in drilling; only it is more difficult to support the work when it is bulky or heavy. The simplest method of drilling is to place the drill in the lathe chuck and hold the piece to be drilled by hand against the drill pad held in the tail stock, using the tail stock hand wheel to feed the work against the drill. In this case, the drill turns as it does in a drilling machine and the work remains stationary. The lathe chuck or face plate is often employed to hold the work to be drilled as at Fig. 4.1 while the drill chuck is supported by the tail stock. The method of supporting a piece when a long hole is to be drilled by using a center rest or back rest clamped to the ways of the lathe is clearly shown at Fig. 4.1. The use of a centering tool which is held in the tool post is outlined in this view.
4.2 GLOBE MILLING AND DIVIDING ATTACHMENTS
Manufactured by Globe Products Mfg. Co. of 3380 Robertson Blvd., Ashley, Los Angeles, California the Globe lathe milling attachment had a principle of operation like that of a "Lincoln" miller where the work piece, instead of moving, was clamped to a table and the cutter head made to traverse across it. Patented during the early 1940s (2,386,461 by Paul Hellman) it very heavily-built with a base machined ready to fit a variety of popular lathes - including Atlas and Craftsman 9", 10" and 12"; Clausing and Logan 10", Sheldon 10", 11" and 12"; South Bend 16", Workshop 9", Model R and Heavy Ten and the Lodge & Shipley 18". Other fittings could be supplied to order and the Company boasted of Government contracts to provide specially equipped and develop units for a variety of novel purposes. Although not mentioned in the advertising literature, the unit may have been made in more than one size and models marked 90-91 50-51 have been discovered.
CHAPTER 5
CONCLUSION
Thereby reducing the cost of the machine can be achieved through milling attachment to a lathe in a reliable and timely manner.
The main part of any milling attachment is a good, heavy angle plate. It can be used by itself, to hold jobs line boring or even milling in cases where vertical is the advantage of building this attachment is its low because the compound rest is normally not utilized attachment, It is used as part of the home built project the vertical feed portion and is ready with its ball crank.
During this task, we have discussed the various types of lathes, accessories, uses, and some of the lathe operations that the machinist will encounter in the machine shop. With proper application, this information will assist those dealing with lathe operations or the machinists that are performing these functions in the metalworking field. In task two and three of this lesson, grinding, milling attachments, and thread forms will be discussed.