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rolled threads 4
- Thread starter thorangle
- Start date
What specifically do you mean by rolled threads? I suspect most threads are made by the "rolling" process and have been since bolts became a standard size. There are numerous types of rolling though, and I am sure that process is continuously changing.
Ralph
Ralph
-
4
- #3
Here's some stuff I dug up...the short and sweet is rolled threads were patented in 1896, and so became prevalent sometime after that. Lathe cut threads have been around in various forms since around 1700.
Here's the long version...
Screw-Turning Lathes
The screw, because of its many applications, is probably the most important of the mechanical elements. It is said to have been invented by Ardeytas of Tarentum, a Pythagorean philosopher and mathematician, about 400 B.C., but is generally associated with Archimedes who died in 212 B.C. Both Hero and Pliny have described wooden screws as having been applied to presses in the first century A.D., but do not appear to have left a description of how these screws were made.
On the other hand, Leonardo da Vinci has again left us with a machine design in which two leadscrews geared to the workshaft enabled the pitch of the screws being cut to be varied at will by changing the ratio between the driving and the driven gears. In this matter da Vinci's machine bears a strong resemblance to a device used in Woolwich Dockyard about 1850. But in his design the leadscrews did not control individual toolposts as seen in the illustration, but acted together to advance a single toolpost spanning the whole machine.
Leonardo da Vinci has recorded the use of the screw both in the making of other screws and the construction of machines, but whether or not his screw-making machines were ever made seems uncertain. Nevertheless, in this matter he was clearly capable of very original thought so, as he was demonstrably much in advance of his time, it seems that he owed little of this to his contemporaries.
The production of screw threads had evidently been exercising the minds of mechanics for a long while, but it was not till about 1700 that a practical solution to the problem presented itself. By this time the design of the lathe headstock had anvanced to the point that would allow the device to be put into practice.
The Traversing Mandrel
This device, introduced about 1700, consisted briefly in allowing the lathe mandrel to slide axially in its bearings under the control of a so that components having short lengths of thread could be produced. Examples of these lathes were installed in a large works where the author was once employed, and there was a complete kit of equipment for use with them. But not much use was made of the traversing mandrel device, the operatives and planners preferring to use other methods with which they were more familiar for the batch production of screwed components. The Traversing Mandrel is depicted diagrammatically here.
The traversing mandrel was evidently well known to clockmakers and ornamental turners in the late 1 7th century, for the description of an ornamental lathe having the device at that time exists. This machine has two forms of tailstock, one apparently able to be set over so that tapers could be turned.
The limitations of the traversing mandrel soon became apparent, so it was not long before many first-class brains turned their attention to alternative methods of screw thread production. Thus the names of such eminent people as Henry Maudslay, David Wilkinson in America, Richard Roberts, James Nasmyth and by no means least, Joseph Whitworth, were concentrating on this problem and others connected with the improvement of the lathe as a practical machine tool.
For screwcutting purposes, the traversing mandrel was superseded by the leadscrew. This is a long screw running the full length of the lathe bed and usually in front of it, though some lathes locate them differently.
The leadscrew can be driven from the mandrel through a train of gears that may be changed at will. A nut attached to the saddle of the lathe engages the leadscrew, so, when the screw rotates the saddle will travel along the lathe bed. The ratio of the gearing that connects the mandrel and leadscrew together dictates the pitch of the screw that will be cut. For example if the mandrel itself turns at twice the speed of the leadscrew then the pitch of the thread cut on the work will be twice that of the leadscrew itself whatever that may be. Small lathes of the type usually have leadscrews with a thread pitch of ~ in. so, when the mandrel makes two turns for each one of the leadscrew, the thread pitch cut will be it in.
Using the principle of which this example is the basis, it will be understood that, by selecting gears to connect the mandrel and leadscrew in the right ratio, a wide range of thread pitches can be cut in the lathe.
Henry Maudslay, 1771-1831, was employed originally by Bramah, the 'locksmith', but left his services in 1797 following a dispute over rates of pay. Bramah himself was a prolific inventor, numbering amongst his designs the hydraulic press and the beer engine, but there is little doubt that he owed much to Maudslay, as a practical mechanic, who perfected Bramah's locks.
Maudslay also produced a machine for winding springs and which set him to consider the problem of screw cutting.
The end of the century saw the production of two further lathes equipped to produce screw threads; one by a Frenchman named Senot, the other by David Wilkinson, an American, who introduced his machine in 1798.
It is at this point that the name of Richard Roberts 1789-1869 becomes important. He had originally been employed by Maudslay, from whom he must undoubtedly have absorbed some sound engineering practice, but in 1814 he left him and set up on his own in Manchester. His claim to fame rests on his introduction, in 1817, of the first practical back-geared headstock to be applied to a lathe.
This information was copied from the book titled "A History of Machine Tools" by Ian Bradley. This book has much more information on early machinery and lathes, and I recommend that you get a copy, if you can find one. (It is out of print.)
Rolled threads
1896
With his business in machinery progressing, Hubbell's next patent was a major breakthrough in the fastener industry: the process and machinery for cold rolled screw threads which reduced the rate of material lost in production by more than 50%. He designed and built progressive blanking and forming dies, patented machinery to slot screw heads, a machine to assemble screws and small parts, devised tools to indicated speed, and patented a changeable speed screwdriver.
Andy
Here's the long version...
Screw-Turning Lathes
The screw, because of its many applications, is probably the most important of the mechanical elements. It is said to have been invented by Ardeytas of Tarentum, a Pythagorean philosopher and mathematician, about 400 B.C., but is generally associated with Archimedes who died in 212 B.C. Both Hero and Pliny have described wooden screws as having been applied to presses in the first century A.D., but do not appear to have left a description of how these screws were made.
On the other hand, Leonardo da Vinci has again left us with a machine design in which two leadscrews geared to the workshaft enabled the pitch of the screws being cut to be varied at will by changing the ratio between the driving and the driven gears. In this matter da Vinci's machine bears a strong resemblance to a device used in Woolwich Dockyard about 1850. But in his design the leadscrews did not control individual toolposts as seen in the illustration, but acted together to advance a single toolpost spanning the whole machine.
Leonardo da Vinci has recorded the use of the screw both in the making of other screws and the construction of machines, but whether or not his screw-making machines were ever made seems uncertain. Nevertheless, in this matter he was clearly capable of very original thought so, as he was demonstrably much in advance of his time, it seems that he owed little of this to his contemporaries.
The production of screw threads had evidently been exercising the minds of mechanics for a long while, but it was not till about 1700 that a practical solution to the problem presented itself. By this time the design of the lathe headstock had anvanced to the point that would allow the device to be put into practice.
The Traversing Mandrel
This device, introduced about 1700, consisted briefly in allowing the lathe mandrel to slide axially in its bearings under the control of a so that components having short lengths of thread could be produced. Examples of these lathes were installed in a large works where the author was once employed, and there was a complete kit of equipment for use with them. But not much use was made of the traversing mandrel device, the operatives and planners preferring to use other methods with which they were more familiar for the batch production of screwed components. The Traversing Mandrel is depicted diagrammatically here.
The traversing mandrel was evidently well known to clockmakers and ornamental turners in the late 1 7th century, for the description of an ornamental lathe having the device at that time exists. This machine has two forms of tailstock, one apparently able to be set over so that tapers could be turned.
The limitations of the traversing mandrel soon became apparent, so it was not long before many first-class brains turned their attention to alternative methods of screw thread production. Thus the names of such eminent people as Henry Maudslay, David Wilkinson in America, Richard Roberts, James Nasmyth and by no means least, Joseph Whitworth, were concentrating on this problem and others connected with the improvement of the lathe as a practical machine tool.
For screwcutting purposes, the traversing mandrel was superseded by the leadscrew. This is a long screw running the full length of the lathe bed and usually in front of it, though some lathes locate them differently.
The leadscrew can be driven from the mandrel through a train of gears that may be changed at will. A nut attached to the saddle of the lathe engages the leadscrew, so, when the screw rotates the saddle will travel along the lathe bed. The ratio of the gearing that connects the mandrel and leadscrew together dictates the pitch of the screw that will be cut. For example if the mandrel itself turns at twice the speed of the leadscrew then the pitch of the thread cut on the work will be twice that of the leadscrew itself whatever that may be. Small lathes of the type usually have leadscrews with a thread pitch of ~ in. so, when the mandrel makes two turns for each one of the leadscrew, the thread pitch cut will be it in.
Using the principle of which this example is the basis, it will be understood that, by selecting gears to connect the mandrel and leadscrew in the right ratio, a wide range of thread pitches can be cut in the lathe.
Henry Maudslay, 1771-1831, was employed originally by Bramah, the 'locksmith', but left his services in 1797 following a dispute over rates of pay. Bramah himself was a prolific inventor, numbering amongst his designs the hydraulic press and the beer engine, but there is little doubt that he owed much to Maudslay, as a practical mechanic, who perfected Bramah's locks.
Maudslay also produced a machine for winding springs and which set him to consider the problem of screw cutting.
The end of the century saw the production of two further lathes equipped to produce screw threads; one by a Frenchman named Senot, the other by David Wilkinson, an American, who introduced his machine in 1798.
It is at this point that the name of Richard Roberts 1789-1869 becomes important. He had originally been employed by Maudslay, from whom he must undoubtedly have absorbed some sound engineering practice, but in 1814 he left him and set up on his own in Manchester. His claim to fame rests on his introduction, in 1817, of the first practical back-geared headstock to be applied to a lathe.
This information was copied from the book titled "A History of Machine Tools" by Ian Bradley. This book has much more information on early machinery and lathes, and I recommend that you get a copy, if you can find one. (It is out of print.)
Rolled threads
1896
With his business in machinery progressing, Hubbell's next patent was a major breakthrough in the fastener industry: the process and machinery for cold rolled screw threads which reduced the rate of material lost in production by more than 50%. He designed and built progressive blanking and forming dies, patented machinery to slot screw heads, a machine to assemble screws and small parts, devised tools to indicated speed, and patented a changeable speed screwdriver.
Andy
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