Tips and tricks
Dies, their construction and use
DIES, THEIR CONSTRUCTION AND USE
For the Modern Working of Sheet Metals.
On the design, construction and use of dies, punches, tools, fixtures and devices, together with the manner in which they should be used in the power press, for the cheap and rapid production of sheet metal parts and articles.
BY JOSEPH V. WOODWORTH.
NEW YORK, NORMAN W. HENLEY & CO., 1903
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Dies, their construction and use
Fundamental designs and practical points by which sheet metal parts may be produced at the minimum of cost to the maximum of output: with special reference to the hardening and tempering of press tools, the use of files, and to the classes of work which may be produced to the best advantage by the use of dies in the power press.
PREFACE
The use of the power press for the cheap production of sheet metal parts (both large and small) has progressed in a truly wonderful manner during the last few years, and, by the adoption and use of suitable dies and fixtures, this modern machine tool has demonstrated its efficiency for turning out work formerly (and even now in a large number of shops) produced by the milling machine, the shaper, the drill press and the forge. Especially is this so where the parts required are of flat soft steel or iron; and in not only one line of machine manufacturing has the power press been used in this manner, but in every line.
The management of the manufacturing establishments in which the power press has been adopted for the production of parts as referred to above, understand and appreciate the full value of dies: and in such shops they and the machines in which they are used have become as great factors in production as any of the other tools in general use.
The rapidity with which the use and adaptation of dies and press fixtures are becoming understood, the endless variety of articles which they turn out, and the great numbers of mechanics who are in various ways engaged in devising and constructing such tools, have suggested to the author that a practical, comprehensive treatise on this subject would be of value and interest to all persons who might be in any way interested in modern sheet-metal working.
In writing this book the author has done so with the purpose of giving to practical men a book which would treat these preeminent factors in modern manufacturing Dies as they should be treated; and that is, from the viewpoint of a practical man. In the pages following are shown engravings of dies, press fixtures and sheet-metal working devices, from the simplest to the most intricate in modern use, and the author has endeavored to describe their construction and use in a clear, practical manner, so that all grades of metal-working mechanics will be able to understand thoroughly how to design, construct and use them, for the production of the marvelous variety of sheet-metal articles and parts which are now in general use, and form an integral part of our twentieth century civilization. Many of the dies and press fixtures shown and described herein were constructed by the author, others under his supervision; while others were constructed by some of our most skillful mechanics and used in some of the largest sheet-metal goods establishments and machine shops in the United States.
We have endeavored to keep all obsolete matter out of this volume, and to make every die and device and press shown represent the highest that has been attained in the development of each type described. The description of the construction and application of the tools, it is to be hoped, will enable the practical man to adopt them for the production of sheet-metal parts and articles to the maximum of output at the minimum of cost and labor. It is the earnest wish of the author that a perusal of the contents of this volume will enable all who may be in any way interested in sheet-metal working to contribute to the manufacture of sheet-metal parts in a manner which is up-to-date, both as to efficiency and working qualities of the output and to cheapness in production.
CONTENTS
- THE CONSTRUCTION AND USE OF "SINGLE" OR BLANKING DIES, AND "DOUBLE" OR PIERCING AND BLANKING DIES.
- SIMPLE DIES FOR USE IN THE MACHINE SHOP
- "GANG" AND "FOLLOW" DIES HOW TO ADAPT AND USE THEM.
- THE ADAPTATION AND USE OF SIMPLE DIES AND PRESS FIXTURES FOR THE ECONOMIC PRODUCTION OF SHEET-METAL PARTS.
- BENDING AND FORMING DIES AND FIXTURES.
- PERFORATING DIES AND PROCESSES FOR THIN AND HEAVY STOCK.
- CURLING, WIRING AND SEAMING PROCESSES.
- DRAWING PROCESSES FOR SHEET METAL SHELLS.
- COINING PROCESSES PUNCHES AND PRESSES FOR OPERATIONS ON HEAVY STOCK.
- THE FEEDING OF SHEET METAL TO DIES LUBRICATION OF PRESS WORK.
- ANNEALING TOOL STEEL, AND HARDENING AND TEMPERING PROCESSES FOR PRESS TOOLS INCLUDING HINTS AND SUGGESTIONS ON THE PROPER USE OF FILES.
- MISCELLANEOUS DIES, PRESSES, FIXTURES, DEVICES AND SPECIAL ARRANGEMENTS FOR SHEET METAL WORKING.
THE CONSTRUCTION AND USE OF SINGLE OR BLANKING DIES, AND "DOUBLE" OR PIERCING AND BLANKING DIES.
In this, the opening chapter, we will illustrate and describe dies which, if adopted, will supersede processes for the production of metal parts which are now obsolete in a large number of machine manufacturing establishments. The only reason for their non-adoption in other establishments is that their application and use are not understood. In such shops, where these strictly up-to-date methods are not being used, special tools and fixtures are being constantly designed and constructed for the machining and finishing of metal parts by milling, drilling or other means, which could be accomplished in half the time by means of dies of simple and most inexpensive construction, in the power press. Aside from the reduced cost of production, the lightness, interchangeability, and fine finished appearance of sheet-metal blanks add greatly to the appearance of the machines to which they are attached, and in many cases improve the working qualities as well.
Let any manager of an establishment which does not number a power press or two among its machine tools stroll through his shop with a power press catalogue in his hand and he will not go far before realizing that he is paying for a lot of unnecessary work. After finishing his inspection he will lose no time in placing an order for a power press, and his toolmakers will be kept busy for some time constructing sets of blanking, piercing, bending, shearing and finishing dies to take the place of expensive milling, drilling and polishing fixtures.
The Construction of a Simple Punch and Die
During a long experience in the making of dies the author has come to know of a number of different methods for constructing single blanking dies, and double or piercing and blanking dies. Every one of these methods has possessed some little kink or way by which the desired results might be accomplished in a manner superior to other methods. So after getting together the best and most practical kinks and ways of all methods, the method of construction here described and illustrated has been evolved.
The Bolster
Before taking up the description of the die, we will devote a short space to the die-block or bolster. Although these bolsters are made in a variety of shapes and sizes, the one shown in Fig. 1 is of a type most generally used for fastening and locating the kind of die indicated. A number of different styles of bolsters for blanking and piercing dies are shown in Figs. 2 to 5. A large number of shops, which make dies for their own use, make a bolster with each die, so as to leave the die permanently within it. But for economy, where dies of an average shape and size are used, two or three are all that are required. When a number of dies are kept in action all the time, or at the same time, then, of course, each die must have a separate bolster.
The Die Blank
In Figs. 6, 7 and 8 are shown a double punch and die used for the production of blanks like Fig. 9; this die is of a type in general use. The punch and die
consist of the following parts: The punch holder or stem A, of cast iron, the punch plate or pad B, of mild steel, the blanking punch C, of tool steel, the piercing punches D, of the same, the stripper and gage plates E, the die F, of tool steel, and the pilot pin G. The shape of the piece to be produced in a die of this type may be any circular or irregular shape desired, as the method of construction here shown is applicable to all, excepting when the blank to be produced is of a very large size or when the metal to be punched is very thick.
As most presses in which punches and dies of this type are used require a punch holder with a round stem, we show one of this sort. When machining the holder great care must be taken to get the working surfaces square with the stem; the faces of the punch plate and stripper plate must be perfectly parallel. When planing the die no great care is required, as it has to be ground after hardening. It should be finished with beveled sides, to fit the bolster, with the edges of the face smooth so as to have a square edge from which to lay out the die.
We will now lay the punch plate, punch holder and stripper plate aside, as they will not be touched until the die proper has been finished.
The Templets
Now in order to lay out the die a templet or master blank is required; this should be made from sheet steel about 3-32 inch thick, and should be filed and finished all over to the exact shape and size required. The two holes should then be laid out in the exact location desired and drilled and reamed to size. Care and accuracy in the preparation of the templet are necessary, as the quality of the work to be produced depends on it.
We now take a piece of soft sheet brass, of the same thickness as the templet, and bend it to the shape shown in Fig. 10, that is to fit across and over the face of the die with the bent ends projecting down the inclined sides of the die about 5-16 inch. This is the female templet, and it should be long enough to allow of its being worked out in the center to fit the male templet, Fig.
9. After having done this the face of the die (which should be polished with a rough piece of emery cloth) should be "blue stoned" and the female templet placed upon it in the proper position, and an outline of the blank marked through it on the face of the die with a sharp scriber. We now remove the templet and proceed to finish the blanking die, which must be accomplished by working the blank through it.
Working the Templet Through the Die
To work a templet through a die proceed as follows: After the surplus stock has been removed by drilling holes about 1-64 inch apart around the inside of the outline and drifting it out, file through from the back to within a shade of the line. Now take the male templet and, holding it by the end of the brass rod, enter it into the die from the back, holding it as parallel as possible with the face of the die. By holding a piece of white paper in front of the die it will be noticed that the die touches the templet at only a few narrow spots; take a lead pencil and mark these spots, making a line at each spot as long as the surface touched. Now remove the templet and file where the marks appear. Keep inserting the templet, marking the spots and filing them away, and in a surprisingly short time the templet will be even with the face of the die, which will be the exact shape and size desired, fitting the templet perfectly.
There are a great many dies of this type in use (which are used for cutting out blanks which are not required to have smooth sides) that it is not necessary to finish the insides smoothly. But there are a greater number in which the finish of the blanks with smooth sides is one of the objects sought. In dies for producing smooth and well-finished blanks the insides should be finished highly, either with a dead smooth file or a scraper.
Giving Clearance to the Die.
In giving clearance to a die a few things must be considered in order to decide upon the proper amount to give. For a die which will only be used to produce a few thousand blanks excessive clearance should be given, say, five degrees, as this will allow of the die being finished quickly. In dies which are to produce large quantities of blanks, and in which the blanks produced are required to be of approximately the same size, one degree is plenty. In giving this one degree of clearance to the die so that it will have one degree of clearance all the way through, the holes that are drilled to allow of removing the surplus stock should be reamed from the back with a reamer of about the taper of 1-32 inch to I inch of length. The reaming of the holes when constructing a blanking die will save a vast amount of filing and the giving of the one degree of clearance will not be difficult.
Locating the Piercing Dies.
The next step in the construction of the die is the locating of the two piercing dies. To accomplish this, place the master blank within the female templet and clamp it to the face of the die in the correct position, allowing for a thickness of metal between blanks. We now take a center drill, which fits the holes in the master blank, and transfer the two holes through it to the face of the die; we drill these holes and then ream them from the back with a reamer of the same taper as the one used for the blanking die. After the holes for the dowel pins and screws by which the stripper and gage plates are to be fastened to the die have been drilled and tapped, and the hole for the stop pin located and drilled, we are ready to harden and temper the die.
Hardening a Blanking Die.
In order to harden a die properly great care should be taken ; first in the heating of the steel, and second in the quenching. In all shops where dies, or other tools which require hardening, are constructed, a gas furnace or "muffler" should be used for heating them. But when a "muffler" is not handy charcoal should be used. After a good clean fire has been built, all screw and dowel holes in the die should be plugged with' fire clay or asbestos. By taking these precautions the tendency of the steel to crack around the holes is, as far as possible, eliminated. We now heat the die to an even cherry red, so that the entire plate will be the same temperature ; then remove it from the fire and dip it endwise into the water (which should be warmed slightly to take the chill out), being careful to dip down straight, and not to move it or shake it around, as that would increase the possibility of the die warping or shrinking excessively. After removing the die from the water it should be immediately warmed. Now grind the face of the die; heat a thick piece of cast iron red hot, and place the die upon it; it can then be drawn evenly to any temper desired. By taking a piece of oily waste and wiping the face of the die as it is heating the different colors will show up clear. When the color denoting the temper required appears remove the die and allow it to cool off slowly.
Making the Blanking Punch.
Now for the blanking punch: Take the master blank or male templet; remove the wire rod and mark the spot where it was attached, so as to know the back from the front of the blank. Then solder the blank, front up, to one end of the piece of tool steel which is to be used for the blanking punch. The punch can now be machined, either in the shaper or the milling machine, so that its entire length will be the shape of the blank, finishing it as close to the edge of the blank as possible. Now heat the steel slightly and the blank will drop off. Clean the blank, lay it aside and proceed to fit the punch. If it is to punch very thin stock make it a tight fit within the die; if for heavy stock, a trifle loose. In order to make a punch a perfect fit for thin stock the edges of the cutting face should be beveled with a file. The punch should then be sheared through the die in the press in much the same manner as a broach is used, being careful to have it in perfect alignment with the die.
Before hardening the punch it is necessary to locate the holes for the pilot pins G. These pins are necessary in order to pro- duce pierced blanks that will be interchangeable. Take the master blank, enter it into the die from the back with the front tip. It will fit the die tightly because of the shrinkage in hardening. Now enter the blanking punch from the top and locate the holes for the pilot pins through the holes in the blank with a centering drill. Drill the holes to size and harden and draw the punch to the temper desired, which should be in most cases a dark blue. In tempering the punch draw it from the back, allowing the temper to run out to the front; thus the back will be almost soft while the remainder will be as hard as required.
DOWNLOAD FREE BOOK: Dies, their construction and use
Let any manager of an establishment which does not number a power press or two among its machine tools stroll through his shop with a power press catalogue in his hand and he will not go far before realizing that he is paying for a lot of unnecessary work. After finishing his inspection he will lose no time in placing an order for a power press, and his toolmakers will be kept busy for some time constructing sets of blanking, piercing, bending, shearing and finishing dies to take the place of expensive milling, drilling and polishing fixtures.
The Construction of a Simple Punch and Die
During a long experience in the making of dies the author has come to know of a number of different methods for constructing single blanking dies, and double or piercing and blanking dies. Every one of these methods has possessed some little kink or way by which the desired results might be accomplished in a manner superior to other methods. So after getting together the best and most practical kinks and ways of all methods, the method of construction here described and illustrated has been evolved.
The Bolster
Before taking up the description of the die, we will devote a short space to the die-block or bolster. Although these bolsters are made in a variety of shapes and sizes, the one shown in Fig. 1 is of a type most generally used for fastening and locating the kind of die indicated. A number of different styles of bolsters for blanking and piercing dies are shown in Figs. 2 to 5. A large number of shops, which make dies for their own use, make a bolster with each die, so as to leave the die permanently within it. But for economy, where dies of an average shape and size are used, two or three are all that are required. When a number of dies are kept in action all the time, or at the same time, then, of course, each die must have a separate bolster.
The Die Blank
In Figs. 6, 7 and 8 are shown a double punch and die used for the production of blanks like Fig. 9; this die is of a type in general use. The punch and die
consist of the following parts: The punch holder or stem A, of cast iron, the punch plate or pad B, of mild steel, the blanking punch C, of tool steel, the piercing punches D, of the same, the stripper and gage plates E, the die F, of tool steel, and the pilot pin G. The shape of the piece to be produced in a die of this type may be any circular or irregular shape desired, as the method of construction here shown is applicable to all, excepting when the blank to be produced is of a very large size or when the metal to be punched is very thick.
As most presses in which punches and dies of this type are used require a punch holder with a round stem, we show one of this sort. When machining the holder great care must be taken to get the working surfaces square with the stem; the faces of the punch plate and stripper plate must be perfectly parallel. When planing the die no great care is required, as it has to be ground after hardening. It should be finished with beveled sides, to fit the bolster, with the edges of the face smooth so as to have a square edge from which to lay out the die.
We will now lay the punch plate, punch holder and stripper plate aside, as they will not be touched until the die proper has been finished.
The Templets
Now in order to lay out the die a templet or master blank is required; this should be made from sheet steel about 3-32 inch thick, and should be filed and finished all over to the exact shape and size required. The two holes should then be laid out in the exact location desired and drilled and reamed to size. Care and accuracy in the preparation of the templet are necessary, as the quality of the work to be produced depends on it.
We now take a piece of soft sheet brass, of the same thickness as the templet, and bend it to the shape shown in Fig. 10, that is to fit across and over the face of the die with the bent ends projecting down the inclined sides of the die about 5-16 inch. This is the female templet, and it should be long enough to allow of its being worked out in the center to fit the male templet, Fig.
9. After having done this the face of the die (which should be polished with a rough piece of emery cloth) should be "blue stoned" and the female templet placed upon it in the proper position, and an outline of the blank marked through it on the face of the die with a sharp scriber. We now remove the templet and proceed to finish the blanking die, which must be accomplished by working the blank through it.
Working the Templet Through the Die
To work a templet through a die proceed as follows: After the surplus stock has been removed by drilling holes about 1-64 inch apart around the inside of the outline and drifting it out, file through from the back to within a shade of the line. Now take the male templet and, holding it by the end of the brass rod, enter it into the die from the back, holding it as parallel as possible with the face of the die. By holding a piece of white paper in front of the die it will be noticed that the die touches the templet at only a few narrow spots; take a lead pencil and mark these spots, making a line at each spot as long as the surface touched. Now remove the templet and file where the marks appear. Keep inserting the templet, marking the spots and filing them away, and in a surprisingly short time the templet will be even with the face of the die, which will be the exact shape and size desired, fitting the templet perfectly.
There are a great many dies of this type in use (which are used for cutting out blanks which are not required to have smooth sides) that it is not necessary to finish the insides smoothly. But there are a greater number in which the finish of the blanks with smooth sides is one of the objects sought. In dies for producing smooth and well-finished blanks the insides should be finished highly, either with a dead smooth file or a scraper.
Giving Clearance to the Die.
In giving clearance to a die a few things must be considered in order to decide upon the proper amount to give. For a die which will only be used to produce a few thousand blanks excessive clearance should be given, say, five degrees, as this will allow of the die being finished quickly. In dies which are to produce large quantities of blanks, and in which the blanks produced are required to be of approximately the same size, one degree is plenty. In giving this one degree of clearance to the die so that it will have one degree of clearance all the way through, the holes that are drilled to allow of removing the surplus stock should be reamed from the back with a reamer of about the taper of 1-32 inch to I inch of length. The reaming of the holes when constructing a blanking die will save a vast amount of filing and the giving of the one degree of clearance will not be difficult.
Locating the Piercing Dies.
The next step in the construction of the die is the locating of the two piercing dies. To accomplish this, place the master blank within the female templet and clamp it to the face of the die in the correct position, allowing for a thickness of metal between blanks. We now take a center drill, which fits the holes in the master blank, and transfer the two holes through it to the face of the die; we drill these holes and then ream them from the back with a reamer of the same taper as the one used for the blanking die. After the holes for the dowel pins and screws by which the stripper and gage plates are to be fastened to the die have been drilled and tapped, and the hole for the stop pin located and drilled, we are ready to harden and temper the die.
Hardening a Blanking Die.
In order to harden a die properly great care should be taken ; first in the heating of the steel, and second in the quenching. In all shops where dies, or other tools which require hardening, are constructed, a gas furnace or "muffler" should be used for heating them. But when a "muffler" is not handy charcoal should be used. After a good clean fire has been built, all screw and dowel holes in the die should be plugged with' fire clay or asbestos. By taking these precautions the tendency of the steel to crack around the holes is, as far as possible, eliminated. We now heat the die to an even cherry red, so that the entire plate will be the same temperature ; then remove it from the fire and dip it endwise into the water (which should be warmed slightly to take the chill out), being careful to dip down straight, and not to move it or shake it around, as that would increase the possibility of the die warping or shrinking excessively. After removing the die from the water it should be immediately warmed. Now grind the face of the die; heat a thick piece of cast iron red hot, and place the die upon it; it can then be drawn evenly to any temper desired. By taking a piece of oily waste and wiping the face of the die as it is heating the different colors will show up clear. When the color denoting the temper required appears remove the die and allow it to cool off slowly.
Making the Blanking Punch.
Now for the blanking punch: Take the master blank or male templet; remove the wire rod and mark the spot where it was attached, so as to know the back from the front of the blank. Then solder the blank, front up, to one end of the piece of tool steel which is to be used for the blanking punch. The punch can now be machined, either in the shaper or the milling machine, so that its entire length will be the shape of the blank, finishing it as close to the edge of the blank as possible. Now heat the steel slightly and the blank will drop off. Clean the blank, lay it aside and proceed to fit the punch. If it is to punch very thin stock make it a tight fit within the die; if for heavy stock, a trifle loose. In order to make a punch a perfect fit for thin stock the edges of the cutting face should be beveled with a file. The punch should then be sheared through the die in the press in much the same manner as a broach is used, being careful to have it in perfect alignment with the die.
Before hardening the punch it is necessary to locate the holes for the pilot pins G. These pins are necessary in order to pro- duce pierced blanks that will be interchangeable. Take the master blank, enter it into the die from the back with the front tip. It will fit the die tightly because of the shrinkage in hardening. Now enter the blanking punch from the top and locate the holes for the pilot pins through the holes in the blank with a centering drill. Drill the holes to size and harden and draw the punch to the temper desired, which should be in most cases a dark blue. In tempering the punch draw it from the back, allowing the temper to run out to the front; thus the back will be almost soft while the remainder will be as hard as required.
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