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Machines And Tools Employed In The Working Of Sheet Metals | by R. B. Hodgson



The scarcity of the literature on Presses and Press Tools is in itself sufficient justification for the publication of these articles, which appeared originally, at intervals, in the columns of The Practical Engineer, and are now published in book form at the request of many readers. The production of tools for the working of sheet metals is a distinctly separate branch from that of engine-fitting and general machine work. It is therefore difficult for an engineer to thoroughly grasp the work of the press-tool maker, unless he has had an opportunity of closely watching the tool work in progress and the subsequent operations performed by the tools in the production of numerous articles made from sheet metals.

TitleMachines And Tools Employed In The Working Of Sheet Metals
AuthorR. B. Hodgson
PublisherThe Technical Publishing Co. Limited
Year1903
Copyright1903, The Technical Publishing Co. Limited
AmazonMachines and tools employed in the working of sheet metals

By R. B. Hodgson, A.M.Inst.Mech.E., Author of "Emery Grinding Machinery."

Dedicated To Professor Hentry Adams, M.Inst.C.E., M.I.Mech.E., F.S.I., Professor of Engineering at the City of London College, To Mark My Esteem For The Author Of The " Handbook For Mechanical Engineers," And My Appreciation Of The Methods Adopted By Him In His Classes On Mechanical Engineering Subjects At The City Of London College.

MACHINES AND TOOLS EMPLOYED IN THE Working of Sheet Metals
-Preface
The scarcity of the literature on Presses and Press Tools is in itself sufficient justification for the publication of these articles, which appeared originally, at intervals, in the columns of The Pr...
-Introduction
For some years past the author has experienced a constantly-recurring need of a practical treatise on this important class of machine tools, as well as of the processes used in the working of sheet me...
-Chapter I. Materials And Measurement
The metals in general use are sheet brass, copper, tin plate, iron, and steel, rolled to the required thickness before reaching the workshop to be cut into blanks and formed into the required shapes. ...
-Chapter II. Micrometer Gauges
The Brown and Sharpe micrometer gauges form convenient and accurate tools for external measurements. They are made in various sizes and styles to measure up to 24 in., and are graduated to read Englis...
-Internal or External Gauges
The standard internal and external cylindrical gauges, fig. 10, and the internal and external limit gauges, fig. 11, are invaluable where accurate production of duplicate parts of machinery or tools a...
-Plate Gauges
Gauges of this type are stamped with the words go on and not go on for external work, go in and not go in for internal work (see fig. 11), and as the two ends are of different shape the opera...
-Chapter III. The Screw Press
This press is also known as the fly press, since adventage is taken of the kinetic energy stored in the rotating mass of theflyoperating the screw. In fig. 12 is shown the elevation of the frame, to...
-Chapter IV. Form Of Screw-Press Frame
THE: most common form of double-sided screw press is shown at fig. 27, in which the top of the frame easting terminates in a boss B, which is lored and threaded or screw-cut to receive the screw a...
-Chapter IV. The Press Screw
Frequently trouble is experienced through the screw we ing badly, and it is by no means an unusual thing to find the screw quite slack after a few weeks' working, even in new machines. Doubtless in ma...
-Chapter V. A Power Press
The press just considered is intended for use in operations where only a very moderate amount of energy is required to complete the operation to be performed, and the attention of the student should b...
-Chapter VI. Faulty Construction
The press shown in fig. 46 has been selected by the author as an example of poor design, and the results obtained in actual operation practically justify the statement that they are complete failures....
-Chapter VII. Dies And Punches
Dies and punches are of infinite variety and shape, special forms being devised daily by engineers in order to produce some new shape that may have to be manufactured. It would be absolutely useless t...
-Punching and Shearing
The term punching is generally understood to include all operations of cutting out blanks from sheet metal The shape cut away is known as the blank, whilst the unavoidable amount of metal sheet left a...
-Punching and Shearing. Part 2
It is sometimes convenient to build up a punch of large diameter for cutting out blanks, and one such composite punch is shown in figs. 69 and 70. In this example the tool consists of three parts, the...
-Punching and Shearing. Part 3
Fig. 73. In another case where the punching was only partially performed, as shown in fig. 74, the thickness of the blank was easily seen to be less than the penetration of the punch without ha...
-Punching and Shearing. Part 4
Fig. 79. Fig. 8o. When the die-forging is circular in shape, then it may be fixed as shown in figs. 79 and 80, by means of either two or three set-screws, which press upon the taper sides of t...
-Chapter VIII. Accuracy and Durability
The durability of dies and punches depends to some extent upon the nature of the work upon which they are used. Further, the work to be done by these tools governs the point as to the amount of accura...
-Standard Dies and Punches
It is interesting to trace the process of making a die and punch to a standard pattern, such for instance as the two ordinary shapes, a pedal plate blank, fig. 83, and a spanner blank, fig. 84, the di...
-Chapter IX. Die Making By Drift
As illustrating how any number of dies may be readily made to one standard size and shape, take the case of a cutting-out die for cycle-chain links. It is possible to make dies or beds of this kind by...
-Die Making By Drift. Continued
The thickness of steel piece B determines the centres of the punches, since the holes for receiving them are drilled at the point where the faces of A, B, and C come together. After the punch holes ha...
-Chapter X. Metal Spinning
Metal shells, after being cupped, drawn, or raised, have sometimes to be expanded, necked, bulged, or otherwise altered in shape. In some instances this is done by means of special expanding dies, and...
-Metal Spinning. Part 2
Now, supposing two such chucks and their rollers to be mounted on the lathe and rotated at a high speed, if the rivet B, fig. 118, be held perfectly central and firmly between the two chucks, and the ...
-Metal Spinning. Part 3
Fig. 124. These centre holes will afterwards serve to guide the drill for drilling the first sized hole in the bosses previous to their being finally corrected by a second drilling in a suitable j...
-Chapter XI. Drawing And Re-Drawing
Drawing proper refers to the cupping of a blank, as in cutting and cupping processes, or in taking any piece of sheet metal in the form of a blank, and producing therefrom any cup-like shape during wh...
-Drawing And Re-Drawing. Part 2
Table I.-Example Of Drawing German Silver Shell For Cartridge Thickness of metal for blank .042. Cupping. 1st process. Extension. 2nd process. Extension. 3rd process. Exten...
-Drawing And Re-Drawing. Part 3
Table III.-Example In Drawing Small Metal Shell Blank .995 diameter by .05 thickness. Cupping. 1st process. 1st re-draw. 2nd process. 2nd re-draw. 3rd process. Heading. 4th ...
-Drawing And Re-Drawing. Part 4
Table V.-Example In Drawing Metal Cartridge Shell„ Thickness of metal for blank 125 in. Cupping. 1st process. Extension. 2nd process. Extension. 3rd process. Extension....
-Drawing And Re-Drawing. Part 4. Continued
Many articles that are made or formed into cups from thick metal may be so formed without the use of a pressure plate, whereas the pressure plate would be essentially necessary with the thinner metals...
-Chapter XII. Presses For Special Work
Definition i.-A raising press is generally understood to refer to a machine that has been specially designed to be used for raising into some hollow shape a previously cut blank. Definition 2.-A draw...
-Presses For Special Work. Part 2
Fig. 156. The single-acting cutting-out press, fig. 157, is one known by Messrs. Daniel Smith and Co. as theGem Series,the special feature of this press that has caused it to receive such a titl...
-Presses For Special Work. Part 3
Fig. 162. A type of press called single-acting is shown at fig. 163, this pattern being used extensively. It3 chief defect is the form of stop motion, that tends to stop the motion of the slide th...
-Chapter XIII. Double-Ended Presses
The advantage of the double-ended type of geared press, fig. 171, is that two presses are fixed and worked, occupying much less space than would be the case if two single presses were-used; further, t...
-Special Stop Motion
The special stop motion used on these heavy presses is of a form particularly suitable for heavy work. It consists of a sliding block, reduced in the extent of its required motion by its surface being...
-Shear of Cutting-out Tools
The shear method of cutting out is usually adopted in the case of large blanking tools, to allow of a large blank being cut with comparatively little power required for the operation, and to reduce th...
-Chapter XIV. Roller And Dial-Feed Motions
The principal reason why the roller-feed finds more favour and is so frequently adopted by sheet metal workers in preference to other feeding devices is on account of it being the only type of feed th...
-Roller And Dial-Feed Motions. Continued
Fig. 189. Fig. 190. It is possible to adapt one dial-plate to a variety of work by making the holes in the plate slightly larger than the largest sized article to be dealt with, then fixing bu...
-Adjusting Double-Crank Presses
A difficulty often experienced with double-crank presses, is the adjustment of the two connecting-rods, so as to ensure that the punch or top die (as the case may be) will come down on to the bottom d...
-Chapter XV. Stamping
The ordinary stamp, consisting of an anvil, two guide rods, pulley, and a hammer that is worked by means of a band or rope upon the principle of the falling weight, is a very useful arrangement, and i...
-Stamping. Continued
Diagram 2. Fig. 1, diagram 1, is a side elevation of such a stamp. Fig. 2 is a front elevation, with one of the standards S removed to show the lifting gear in section, and the other part sectione...
-Chapter XVI. Automatics And Machine Tools
It is necessary for those who are fitting out new factories to have had a reasonably extensive experience, in order that commercial success may result. It is important to emphasise this, particularly ...
-Automatics And Machine Tools. Part 2
The lathe may be truly said to stand of first importance in the equipment of a tool room which has to deal with press tools. A useful 6 in. centre tool-maker's lathe is represented at fig. 211. The he...
-Automatics And Machine Tools. Part 3
Fig. 219. The use of drilling and profiling machines has long been associated with the manufacture of small arms and sewing machines. The chief application of the profiling machine was the for...
-Chapter XVII. Tools And Jigs For Repetition Work
The lathe test indicator, fig. 232, is for use in setting central any point or hole in a piece of work to be operated upon in a lathe or upon a lathe face-plate. It may also be used for testing lathe ...
-Chapter XVIII. Interchangeable Machine Parts
Machines of somewhat small and delicate design are frequently required in which their members must necessarily come together accurately and yet be interchangeable. A machine of this description is sho...
-Chapter XIX. Press Tool-Setting
The old adage-an incompetent workman finds fault with his tools-is as true in press work as in any other industrial department. No matter how well designed and equipped a works may be, unless the sho...
-Press Tool-Setting. Continued
Fig. 252. The old system of stripping, which is even now practised to a certain extent, is to have a slot cast through the back of the press in single-sided presses, and in double-sided presses a ...
-Hardening and Tempering
In the case of cutting, shearing, stamping, drawing, and similar tools that have to be hardened to enable them to deal with sheet metals, it is necessary to exercise special care in heating them to th...
-Annealing Metal
Sheet metals are usually purchased at the proper temper ready to be sheared or cut into blanks, but in drawing tubes or shells the action of the tools rapidly hardens the metal, thereby making it nece...
-Table of Colours for Tempering
Faint straw............................ Scrapers for brass. Steel-engraving tools. Light-turning tools. Hammer faces. Planing tools for steel. P...
-Annealing Dies and Tools
When dealing with cutting-dies, punches, stamping-dies, or any piece of steel which has to be worked or shaped by the action of cutting tools when In the cold state, previous to the tool being hardene...
-Chapter XX. Blank Dimensions
The three methods generally used to find the dimensions of a sheet metal blank are the tentative, the gravitative, and the mensurative-probably, as a rule, more time is spent in experimenting to obtai...
-Blank Dimensions. Continued
The h1 + ( D - d 2 / 2) will give the slant height S. The full equation will therefore be Area = {D+d/2 h1+( D - d / 2)2}+d2 /4 = 3.1416 { 4+2 /2 6.25+1}+ 3.1416 = 2...
-Chapter XXI. Pressures For Cutting Blanks
Although shearing and punching may be considered a true cutting action, it is of a rough character. It has been previously explained that at times a punch and die is made flat, at other times concave ...
-Definitions
The technical student and practical mechanic will find the following definitions of terms assist him to a better under-standing of the problems concerned:- The unit of work is the work done in liftin...
-The Power of Presses and Stamps
When considering the power required to perform work in either a press or stamp difficulties arise under the usual working conditions which make it impossible to obtain reliable results by any known fo...
-Work Of Fly Press
By reviewing the action of the fly press, it will be interesting to see how the work accumulated in a moving body is applied to overcome the resistance offered when punching holes in metal plates. In ...
-Work Done by Stamp Hammer
The stamp hammer is an example of the useful application of the principle of the falling weight. In finding the work accumulated in any moving body, such, for instance, as energy stored up in a flywhe...
-Practical Engineer
Published simultaneously in London and Manchester every Friday. The Best Weekly Journal of Mechanical and Motive Power Engineering. Subscription (including Free Copy of Pocket Book, if ordered direct...









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previous page: Practical Sheet And Plate Metal Work | by Evan A. Atkins
  
page up: Metalwork Books
  
next page: The New Metal Worker Pattern Book | by George Watson Kittredge