US1635945A - Manufacture of wire-drawing dies - Google Patents

Description

July 12 1927 K, B. LEWIS ETH MANUFAC'TURE oF WIRE DRAW-'ilus DIES Filed Marcnm, 19224"l Patented July l2, 1927.

UNITED STATES PATENTOFFICE. i

KENNETH B. `LEWIS AND1 FRANK H. ELLSWORTH, `0F WORCESTER, MASSACHUSETTS,

ASSIGNORS TO MORGAN CONSTRUCTION COMPANY, OF WORCESTER, MASSACHU- SETTS, A CORPORATION 0F MASSACHUSETTS. e

murnc'runn or WIRE-nnAWING mns.

Application inea marcan, 1924,` serial No. 699,263.

Our invention relates tothe manufacture of wire drawingdies and has for its ob'ect to provide an improved methodl of pro ucing dies capable o'l accurately finishing more wire than diesz heretofore Adem lcyed ,forl ,the same purpose. A further obgect of ourinvention is to provide an improved method, by the `practice ,of which. larfge numbers' of dies can `be produced which willbe nabsolutely uniform Cas regards thejsize 1an-d shape of the orifice through which "the metal drawn and all of which dies will have the same degree of hardness. Astillfurtheryobject is to provide anviinproved method car pable of being carried on by vcomparativ'ely l unskilled operators with a consequentv saving in manufacturing costs, as willA hereinafter appear.'

In the manufacture of the wire drawing dies, the formation of the orifice, or hole, through .which the metal is drawn, is of the utmostimportance, and Ythe accuracy of the die and the amount of metal which V.may be drawn therethrough is very largely' deter# mined bv the manner of forming` the hole. Therefore, in order that the nature and scope of rour invention may be fully understoodthere follows a brief discussion of the methods heretofore commonly employed in the manufacture of wire drawing dies. In the production of dies Vcomposeilv of chilled cast iron,the holes are reamed to exact size by skilled operators, the real nin of the holes involving the `actual removal o' metal from the die. It is usually ssible to draw only one bundle of wire: rough the hole of a cast iron die, after whichthe hole must be rearned out again' to `a larger size by a skilled operator, this procedure being followed after each draft 'until the hole becomes too large for the strength of the die and the die is scrap ed. 1

In the production of stee dies to be used for drawing Ordinar sizes of wire, agrade of steel is employe whichv will harden if heated and quenched. The usual practice when `producing steel dies is to keep the metal in an annealed state, 'hardening the metal only in the immediate vicinity of the hole by coldworking. V`When it is desired to reform a worn holeV ina steel die, the worn-out hole is partially closed by hand hammering the metal around thesame.

the operator.

hammering hardens vthe metal and at the same time crowds the` metal into ther-hole so that, after hammering, thehole is smaller. f

The hammered hole is then enlarged to its original size by careful hand punching,y

which shapes and sizes the hole and further hardens the metal. The restoring. of a hole to size requires considerable skill and experience on the lpart of the operator, for f the hammering must neither be toojheavy nor too light, and the blows must be evenly spaced around the hole 'and not too close to it. The tool with which, the hole is punched to its final size is tapered, sothat'the size of the hole depends'upon the `depth to which the punch is driven."` Therefore,` great skill must be .exercized by the yoperator when punch-ing the hole, and the size ofthe hole "must be tested after each blow on Vthe punch.

The operation of` resetting holes in steel dies of thisy 'character' isy obviously slow and costly, the, success of the operationv depending largely on the vskill and Vexperience of It is usuallypossible to accurately draw but one bundle through a reset hole of a' soft steel die.

In the ,drawing of large sizes of` wire, w'hi'ch are to have only aslight'red'uction,

steel. dies haveheretofore been employed to a limited extent which have been hardened by heating and quenching. In the. production of such dies, a stream ofwater isrpasse'd through the orifice while the 4metal is red hot and in the resulting shrinkage'of the 'imetah theopening becomes'snialfler than its `original size. The opening is then restored toits original size by lapping, that is, by the use ofa suitable 'rotating toolcarrying "an abrasive which removes the scale and brings the hole to true roundne'ss. Hardenedl and lapped steel dies requirefmuch skillin their preparation, and both `the Adies and `the holes must be so shaped as to secure uniform'shrinkage.

` From a consideration of the above, it is 'apparent that inl all cases the working, or

resizing, ofthe holes requires skilled operators,y and 4that it is always diicult to obtain absolute uniformity' in the sizes of holes owin "to the fact that practically all the work is.4 oneby hand. Furthermore,an entire mill employing perhaps two hundred or .three hundredimn, may *be ythrown out' qof employness of the metal.

ment temporarily by the absence from work of two or three skilled die workers.

As previously pointed out, it is the object of our invention to provide an improved method of producing dies capable of accurately tinishing more wire than either cast- .iron or soft steel dies as previously made, the practice of our invention permitting the production oit' large numbers of dies absolutely uniform as regards the size and shape of the opening and the degree of hard- The production of dies by the practice of our invention is in no way dependent upon the manual skill of operators, the uniformity and (piality of the product being assured by mechanical means, will hereinafter more fully appear, reference being had to the accompanying drawings in which i Fig. 1 is a sectional view of a die at the time of carrying out the first' step of our method.

Fig. 2 is a diagrammatic view illustrat- `ingmeans for carrying ont the second step of our method.

- Fig. 3 is a sectional view similar to Fig. 1, showing the ap earance of the die after the performance o the second ste Fig. 4 is a diagrammatic view i lustrating means for carrying out the third step of our method.

Fig. 5 is a view of the punch used in Fig. 4. l

Fig. 6 is a view'similar to Flg. 1, illustrating the appearance of the die after the performance of the third step of our method.

Like reference characters refer to like -parts in the different figures.

'Referring' to theV drawings, Fig. 1 illustrates a usual formof die 1 preferably composedv of a high grade of steel. The die is provided with a hole 2 originally formed, roughly, in any desired manner, at the time of making the die, and our invention has to do with the setting or resetting of this hole 2, preparatory to drawing wire therethrough. rl`he hole 2 flares outwardly on one side of the die to guide the wire to the reduced cylindrical portion 2 of the hole which determines the size of the wire drawn therethrough in the direction of the arrow In drawing wire through the cylindrical or reducing portion 2a, it has been found that the metal of the die is worn away, as indicated in dotted lines at o, a, in Fig. 1, thus forming' an annular pocket surrounding the entrance to the reducing portion 2a. The formation of this pocket soon destroys the accuracy-of the die which must then be reset. At this point itshould be borne in mind that in the practice of our invention, it is immaterial whether the hole 2, shown in Fig. 1, is that of a new die which is to be set for theifirst time, -or whether it is the worn hole of an old die which is to be reset.

,In carrying out our invention the die 1 is placed in azsuitable heating furnace in which it is heated to a temperature well above its critical point. The furnace employed for heating the die is preferably of the type in which the degree of heating of the material therein may be controlled so that when a number of dies are successively placed inthefurnace, all o-l" them will be brought to substaijitially the same temperature. f

rllhe die having been heated to the desired degree, it is withdrawn from the furnace Yand immediately placed on the bed if) of a hammering machine, diagrammatically illnstrated inv Fig. 2. lThe hann'nering machine isof the automatic type in which the hammering element 4t always operates in a uniform manner and is always adapted to strike an object placed. on its bed 3y at the same rate and with the same force for a. given setting of the machine. An automatic hammering machine of this type is fully vshownand described in U. S. Patent No. 1,310,968, issuedJuly 22, 1919, to Connor and Slinger, and it is not believed necessary to burden the present application with a detailed description thereof.

Suffice to say that when the machine shown in Fig. 2 is set in operation, the hammering element 4 is adapted to strike the 'face 1a of the die 1 a series of blows distributed around the opening 2, the blows being delivered in a generally spiral path automatically determined by rotative movement of the bed 3 and simultaneous movement of the `elem-ent 4 withV respect to the axis of the die hole 2. For a given setting of the machine7 the haminering. of each die placed on the bed 3 is exactly the same and is carried on independently of the operator of the machine.

The above described han'n'nering of the die 1 in its heated condition causes the metal therein to be somewhat condensed. around the opening 2 so that the cylindrical portion 2 is, after hammering. slightly snialler than this portion was before being heated. The contraction of the openingl 2 is shown on a somewhat exaggerated scale in Fig. 3. from which it is apparent that the pocket (L shown in Fig. 1 has disappeared, and that an annular shoulder has taken its place.

'lne'han'lmered die l is then immediately placed, While still hot, on the bed 5 ot a power punch. which is illustrated diagral'nmatically in Fig.- t. vThe punching tool (i of this machine is the exact size and shape of the desired die opening and the machine is of such a type that upon release of its clutch, or other controlling device, the punching toolG is adapted to `make one stroke in the die 1.to a predetermined depth. The tool 6 is shown in Fig. 5, from which it is apparent that the working stroke of the tool 6 lill 1n the heated die 1 shapes the lhole2`to the 'i Lllvihilewe'. are aware that the hammering exact size and .shape as shown in Fig.

The punched die 1 is then moved' from the punching machine, whilestill in a heated condition, and is dropped into an oil bath which serves to harden the metal by quenching. I y

The above described operations are adapted to be carried out in rapid succession, and each die that is handled in accordance with our method is treated in exactly the same manner. lVhen a number of dies are being handled, they are all brought to the same temperature by the continuous heating furnace, after which the automatic hammering machine operates upon each of thev dies in the same manner, the amount of hammering which each die undergoes notbeing susceptible of control by the operator. The dies are then all operated upon by the punching machine in exactly the same manner, the punch 6 always descending to the same point with relation to the bed 5, and with relation to the die face, so that the holes 2 produced in successive dies are identical in size and shape. By reason of the fact that each die is operated upon in exactly the same manner, the dies reach the oil at a uniform temperature and are consequently hardened to exactiy the same degree. v i v Te have found that dies producedby the practice of our invention being exactly uniform, as regards the size of the o enings and degree of hardness, are also uni orm in their behavior when used to draw wire, that is to say, a. number of dios formed in accordance with our invention are adapted to pro- `duce wire of uniform size, and we have found that such dies will satisfactorily finish about six times as much wire Vas cast iron, or soft steel dies, used for the same purpose. y u

Furthermore, the production of dies in accordance with our invention can be carried on with much less labor and expense than has heretofore been necessary for` setting of cast iron or steel dies. Obviously the heating, hammering, punching, and quenching of dies in accordance with our method can be carried on by comparatively unskilled operators, inasmuch as the hammering and punching machines are entirely7 automatic in their operation, while the degree of heating and cooling of the dies is determined entirely by the control of the heating furnace and the length of time it takes a die to be operated upon by the hammering and punching machines. The fact that the dies require no handling, otherthan the mere transfer from one machine to another, results in dies being set at a much faster rate by the practice of our invention than is possible when the setting is performed by the manual labor of skilled operators, as previously described.

and punching of `dies hasv beenheretofore carried y,en byhand, we believe that the automatic hammering ofy ydiesfollowed by hot vvowel' Cpimchi'ng as a. means of producing al nislie hole, "is enti-rely new. We have in carrying out? our invention that 'thequenchingof the"diesffafter hot punching results in the production of a finished hole which it is not necessary to lap out in order to polish the hole and free it from scale. This production of a finished hole by a singleoperation is doubtless due to the fact that the punch which entersand iinishes the V hole in the hot die leaves a filmof oil which burns and protects the sides 'of vthe hole against oxidation until it is quenched.

We claim, Y y' 1. The improvement in the art of manufacturing wire drawing dies, which consists in heating dies to a uniformvdegree, automatically hammerlng the heated dies a uniform amount, power punchingfthe heated.

dies in the same manner, and quenching the punched dies to obtain a uniform degree of hardness.

2. The iniprovcment in the art of manufacturing wire drawing dies which consists in power punching a heated die by a single quick stroke to produce a finished hole therein, the punching being immediately followed by quenching to harden the die.

3. An improved method of making wire drawing dies,v which consists in first heating a die a predetermined amount, then automatically hammering said die, then power punching said die by a single quick stroke to produce a finished hole, and finally in hardening said die by quenching. y

4.v An improved method of making wire drawing dies, which consists in lirst heating a die to a predeterminedl degree, then automatically hammeringsaid die a predeter-V mined amount, then power punching said die by a single quick stroke to produce a finished hole of a predetermined size, and then hardening said die by quenching.

5. An improved method of making wire drawing dies, which consists in first heating a die to a point above its critical temperature, then automatically hammering said die out of its original form, then power punching said die by a single quick stroke to produce a finished hole of predetermined size, and finally `in hardening said die by quenching.

6. An improved method of making `wire drawing dies, which consists in iirst heating a die to a predetermined temperature, then subjecting said die to the action of an automatic hammering machine which alters the shape of the die orice a predetermined `degree, then subjecting said die to a single quick stroke of a power punch with a tool of predetermined shape and size,` which penetrates said die to a predetermined depth, end finally in hardening said die by quenching.

7 An improved method of making Wire drawing dies, which consists in heating a number of dies to the same degree, then hammering each of said dies a predetermined amount, then power punching each of seid dies by ey single quick stroke to the same size and depth, and finally in uniformly 10 hardeningeach of said dies by quenching at the same temperature.

Dated this third day of March, 1924.

KENNETH B. LEWIS. FRANK H. ELLSWORTH.

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