US2196497A - Method of forming tubular members having thick walled end portions - Google Patents

Description

April 9, 1940. H. D.'HEMAN\ METHOD OF FORKING TUBULAR MEMBERS HAVING THICK WALLED END PORTIONS 3 Sheets-Sheet 1 Filed Dec. 30, 193'? HOMER D. HEMAN ATTORNEY.

H. D. HEMAN 2,196,497

METHOD OF FORIING TUBULAR MEMBERS HAVING THICK WALLED END PORTIONS A n'ls, 1940.

Filed Dec. 50, 1937 3 Sheets-Sheet 2 INVENTOR HOMER D. HEMAN a ATTORNEY.

April 9, 1940. HEMAN 2,196,497

METHOD OF FORIING TUBULAR MEMBERS HAVING THICK WALLED END PORTIONS Filed Dec. 30, 1937 :s Sheets-Sheet s 3o 29 INVENTOR. fiQJ? fi 15 HOMER D. HEMAN I @ATTQRNEY.

Patented Apr. 9,1940

UNITED STATES PATENT OFFICE METHOD OF FORMING TUBULAR MEMBERS HAVING THICK WALLED END PORTIONS Homer D. Heman, East Cleveland, Ohio, assignor to The Ajax Manufacturing Company, Euclid Village, Ohio, a corporation of Ohio Application December 30, 1937, Serial No. 182,557

3 Claims.

This invention relates to an improved method of producing a tubular metal member having portions of varying wall thickness and particularly end portions and end flanges of greater wall thickness than the normal wall thickness of the portion of the tubular member between the end portions and to a method of preparing a steel blank by roll forging for producing such tubular metal members.

For the purposes of illustration, the present invention is described herein in connection with the manufacture of torque tubes for automobiles, its application to other metal tubularmembers being readily apparent from the exemplary description and drawing.

Heretofore, tubular members of this general character, and particularly torque tubes for automobiles, have been formed by any one of three generally practiced methods. The first method consists of providing thick wall flanged sleeves which either are cast or separately forged. These sleeves, in turn, are telescopically fitted over the end portions of a length of tubing of uniform wall thickness and then spot welded or riveted to the length of tubing so as to provide a substantially unitary structure. This method has been more or less superseded by butt welding preforged heavy-wall flanged sleeves to the ends of a length of tubing of uniform 'wall thickness or with an end slightly reduced in diameter and the end wall portion slightly thickened by swaging. The advantages of a torque tube having its end portions thickened and formed into integral flanges are such, however, that the practice he came established of upsetting the ends of the tube to provide the additional wall thickness desired and then forming one of the extreme end portions of the tube into an annular or butt flange, and the other end portion of the tube either into a similar flange or bell, depending upon the particular requirements of the torque tube.

This forging method, however, has proven expensive. For example, in forming the flanged butt and of the torque tube or the bell end, it is necessary to heat the end of the tube and, while the end is hot, to place it in a suitable multiple impression forging die in an upsetting forging machine and therein to subject it successively to several upsetting operations; After the second, third, or fourth step, depending on the thickness of the tube wall and the speed at which heat is dissipated, it is necessary to reheat the tube and subject it to several additional successive operations in a different multiple impression forging die, the last step of which finally forms the end portion of the tube to the desired form and thickness and, if desired, with the proper flange. r

The number of upsetting or forming steps required is determined by the ratio between the cross sectional area of the tube and the volume of the enlargements, but the operations must be gradual to avoid the folding or wrinkling ofthe tubular walls which would result in subsequent injurious defects, such as so-called cold shuts, in the reinforced or thickened sections of tube. Sometimes the total number of operations can be'accommodated in one pair of multiple dies of one forging machine but even so the necessity of reheating to avoid working the stock too cold calls for double handling at the furnace and forging machine. More frequently the number of operations required when upsetting portions of stock tubing into heavily reinforced ends and flanges is such that all the operations cannot be performed in the dies of one forging machine and a second machine, with a second furnace, must be provided, all of which adds greatly to the labor of handling, expense of the operation,

and cost of equipment. Thus these operations necessarily require considerable machinery and labor, and, more important, require considerable time and handling of the member being forged, due to the reheating operation.

One of the-principal objects of the present in-, vention is to provide an improved method of producing a metal tubular member with integral thickened and reinforced Wall portions of this character and which requires fewer upset forging operations with the consequent reduction of time and handling of the material than the methods heretofore employed and as a result of which rejections because of defects or cold shuts developed during the process and consequent ruin Another object is to provide a method by which such tubular members may be formed more con- 7 blanks or strip stock so as to provide blanks having thickened end or ends, or intermediate portions, then forming said blanks into tubular form, welding the longitudinal edges of the same so as to provide a tubular member having certain wall portions initially thickened in advance of the die forging or upsetting operations, and then finally heating the thickened portions and subjecting them to successive combined upsetting and forging operations suficient to complete the desired formation of said portions without additional reheating.

Another specific object is to roll forge a blank of flat metal of such shape and proportions that it can be sheared into strips which, when formed into tubular form, produce tapered tubular blanks with initially thickened wall portions.

Another object is to design the shape of the blanks for forming tubular members which are to be tapered toward one end in such a manner that the blanks are in edgewise nested relation to each other and may be sheared from fiat band stock without waste of material, labor or time.

Other objects and advantages will become apparent from the following specification, wherein reference is made to the drawings, in which:

Fig. 1 is a plan view of one form of .blank to be operated on in accordance with the present in vention for forming a tubular member or torque tube of substantially uniform diameter throughout the major portion of its length and slightly tapered inwardly toward one end;

Fig. 2 is a side edge view of the blank illustrated in Fig. 1;

Fig. 3 is a plan view of the blank after. it has been subjected to the first step of the present method;

Fig. 4 is a side view of the blank illustrated in Fig. 3; i

Fig. 5 .is a longitudinal sectional view of a partially formed torque tube which has been l t t d Fi 5 us m e m g and showing the final form the intermediate portion being merged with the thereof;

Fig. 7 is anenlarged fragmentary sectional view through the completed bell end portion of the tube taken on a plane indicated by the line l-'l of Fig. 8, exemplary successive configurations of the end portion of the tubular member resulting in the bell portion being indicated in dotted lines and dot-and-dash lines, respectively;

.Fig. 8 is a cross sectional view taken on a plane indicated by the line 8--8 in Fig. 7;

Fig. 9 is a sectional view of the thickened end portion of the tube member taken on a plane indicated by the, line 9--9 in Fig. 7;

Fig. 10 is an enlarged fragmentary longitudinal sectional view through the flanged or butt end of the tube illustrated in Fig. 6;

Fig. 11 is an end elevation of the tube portion illustrated in Fig. 10;

Fig. 12 is a plan view of a strip of metal illustrating the manner in which nested blanks for a tapered tube may be cut from the metal'without wasting the material;

Fig. 13 is a side elevation of the band of stock with the formation of a torque tube for automobiles, their application to other tubular members being readily apparent from the exemplary description and drawings.

The torque tube shown by way of illustration of the present invention is one which is tapered near one end and is to be provided with a bell portion at the tapered end portion and with a radial flange at the opposite or butt end. For this purpose, a length of the desired rolled strip metal is cut off for forming a blank such as illustrated at I, the stock material used being of proper width so that lateral trimming to size' is unnecessary preparatory to the first step of the method.

The blank I is then heated and passed between the rolls of a roll forging machine, one roll of which may be of constant diameter and the other roll of which may be either a. segmental roll or a complete roll having a reduced diameter portion. In passing the blank i between the rolls, the rolls are so positioned initially that the extreme leading end portion 2 of the blank is either not reduced in thickness or' is reduced in thickness a less amount than the remainder. The rolls likewise are such that at the opposite or trailing end portion 3 of the blank I, the extreme end is not reduced in thickness at all or is not reduced as much as the longitudinal midportion of the blank.

For the particular tube illustratively shown herein, the rolling operation forms the blank such that substantially the entire leading end portion 2 and trailing end portion 3 are of their original thickness, while the intermediate portion t of the blank is of a reduced thickness,

portions 2 and 3 by sloping portions 5 and B, respectively, which are of gradually'reduced thickness. The intermediate portion 6 of the blank l, between the portions 5 and 5, is reduced in thickness to the gauge desired for the corresponding intermediate portion of the finished tube.

manner, the blank elongates materially at the portion i so that the original blank may be cut to a length considerably less than the length of the finished tube to be formed therefrom. Further, during this operation, the blank widens slightly and the lateral edges are slightly irregular, as indicated in Fig. 3. Since the blank is to be formed into a welded tube, accurate edge surfaces are required to form the seam cleft. Consequently the marginal portions of the rolled blank are sheared oif, thus providing the correct width of the blank and at the same time providing accurate edges for the subsequent Welding operation. Only suflicient material need be removed at the margins of the blank to provide the correct width and shape of finished blank.

In the form illustrated, the tube is to be tapered at the bell end, that is, at the end portion 2; and consequently more metal is trimmed ofi of the lateral margins of the blank at the end portion 2. The trim or shear line of the During the roll-forging of the blank I in this blank for forming the particular tube illustrated, is indicated at I in Fig. 3. By shearing after roll-forging, not only is the blank brought accurately to shape but also the raw edge surfaces to be welded are clean cut and in most desirable condition for the welding operation.

The blank I, after the roll-forging operations,

, blank defining the seam cleft, as indicated at I0.

In this condition, the seam is welded, preferably by stitch welding or other well known methe ods.

In the form illustrated, the blank has been rolled or pressed into tubular form with its under surface in the position shown in Fig. 4 forming the outer surface of the tube, thus causing the thickened material to be disposed inwardly toward the axis of the tube in which position it may be more easily upset without danger of folding.' In some instances, as will later be pointed out, the reinforcement or relatively increased thickness can be disposed to the outside of the tubing or partly to the inside and partly to the outside.

Assuming the bell flange end is first to be formed, the left end of the tubular blank illustrated in Fig. 5 is heated and without reheating, is subjected to successive impressions of a multiple impression forging machine die, exemplary operations performed by the successive stages of the machine being illustrated in Fig. 7. In the first impression the end portion 2 is additionally upset and thickened while remaining tubular in form, as illustrated by dotted lines l2 in Fig. 7.

In the next impression, the end portion 2 is partially flared, as indicated by the dot-and-dash line I3 in Fig. 7. In the third or final impression of the machine, the portion 2 is given its final bell form, as indicated at H in Fig. '7. If extreme thickness of the bell portion is not necessary, the end portion 2 may be formed to the shape indicated at IS in Fig. '7 in the first impression of a two-stage forging machine, the second impression of which machine imparts the final form, indicated at H. Thus both the bellflanged portion of the tube and the contiguous part of the portion 2 are of greater wall thickness than the wall thickness of the intermediate portion 4.

Referring next to Figs. 10 and 11, the successive steps of forming the radial flange or butt end of the torque tube are illustrated. After the formation of the bell end the butt end of the tube is heated. to a required degree and subjected to successive combined upsetting and forging operations of a multiple impression die forging machine, the first of which impressions additionally upsets and forges the thickened portion 3 to the shape indicated by the dotted line I! in Fig. 10, the second impression of which additionally upsets and forges the end to the shape indicated by the dot-dash line it in Fig. 10'and the third impression of which forms a portion of the end of the tube into the final form with a thickened wall portion and a radial flange i'l. During each of these successive combined upsetting and forging operations, the wall thickness or the tube at the portion 3 may be slightly increased at the outer end.

The relative thickening of the end portions of the blank results in a very pronounced saving in time and an increase in the uniformity and high quality of the product over prior known methods. In this connection it should be noted that the thickening of the wall by upsetting in such forging operation is, as to each forging impression, about 50% of the wall thickness existing at the beginning of that particular operation. If the thickened end portions are formed from tubular stock having original thickness of the portion 4 of the blank, it is apparent that the increase in thickness which could be obtained in each forging operation would be materially reduced,- and if an' attempt were made to increase the wall thickness more than about 50% of that existing at. the beginning of the particular op- .eration the metal would fold and overlap; By

starting with the increased wall thickness in the first instance at the portions 2 and 3, not only are the several forging impressions which would be'required to obtain this thickness eliminated but also the increase of thickness for the steps actually used is much greater per step. This effects a further reduction in the time and number of operations required to obtain the final thickness desired. This, of course, is due to the fact that, in the fizrst forging operation, the amount of thickening is 50% of the original thickness of the metal strip at the portion 3 instead of 50% of the reduced thickness of the portion 4 of the blank.

In the preferred embodiment of my method heretofore described, the blanks were formed preferably from strip stock of substantially the width desired in the finished blank, thus saving the cutting operations which would be necessary to out such blanks from a wider band of material.- The advantages of this, however, areoilset in some instances by the loss of material in trim at the end portion 2. In many instances, it is desirable to form torque tubes which are tapered for substantially their full length and in such instances the cutting of the blanks therefor from suchstrip stock would result in a considerable waste of material.

For tapered tubes, therefore, it is desirable to lay out the blanks in nested condition as illustrated in Figs. 12 and 13, wherein a band of strip steel 20 of a width conforming to the length of the blank desired, allowance being made for elongation during rolling, is cut into blanks 2i tapered from end to end of the blanks, that is, laterally of the original strip stock, as indicated at 22. The blanks are nested with the large end of each blank being arranged between the smaller ends of adjacent blanks. Thus, in the blanking operation, no metal is wasted.

The resultant blanks 2| are then roll-forged in the manner heretofore described so as to provide the thickened end portions 23 and 24, respectively, with the intermediate portions 25 reduced in thickness relative to the original stock. After the roll-forging operation of such blanks, the marginal portions 26 are trimmed off at the portion of the blanks of reduced thickness along the lines indicated at 21, At the same time, the marginal portions of the unreduced end portions 23 and 24 are trimmed off along the lines 28 so as to provide accurate and clean-cut edges for welding and at the same time to render the lateral edges of each end portion parallel to each other.

The blank is then formedinto the tube and forged at the ends as heretofore described. The, resultant tube, indicated at it in fig. in, is tapered and provided at its ends with flanged portions,

as indicated at St and 35, respectively, these portions being formed in the same manner as the bell flange and butt flange portions or the torque tube heretofore described.

As heretofore explained, the invention ha been described particularly in connection with the forming of torque tubes for automobiles, wherein all of the advantages of the method are fully developed and utilized. In such tubes, it

is advantageous that the reinforcement or relative thickening of the walls be disposed to the interior of the tube and the thick or reinforced portions of the tube occur only at one or both ends, the intermediate portion of the ,tubebeing of less thickness.

There are instances, however, in which it is desirable to provide tubes with reinforcement at some other portion than at the ends and to disinforcement may be effected by the'steps of rollforging the blank to provide relatively thickened wall portions so that when the blank is formed and welded into tubular form, certain desired portions are already initially thicker than others. In such instances, it is often possible to eliminate the additional upsetting forging steps, as sufficient reinforcement can be provided. in the roll forging operations. When such tubes are comparatively long, the blanks therefor are passed through completely cylindrical forging rolls so arranged that the gap between the rolls can be increased readily when desired, thus providing the relatively greater thickness by sop:

arating the rolls to the desired degree as the proper portions of the blank pass therebetween.

When the reinforcement is to be disposed partially on the inside and partially on the outside of the tube, it may be provided for by undercutting both roll forging dies at the zone where the additional thickness is required. Again, it is sometimes desirable to provide thickened portions, such as reinforcing bosses, atelifierent areas of the tube, both on the inside andon the outside of the tube, for the purposes of strengthening the tube to afford a stronger wall at the zone of connection with other members. The provision of the reinforcement at separated areas or zones of the tube is of particular value in connection with members such as tubular front axles wherein the heavy bosses or reinforcements of the tube wall are required at the spring shackle posts and for the king pins. For this purpose, the roll forging dies may be undercut at the desired areas so as to reproduce on the flat blank the necessary reinforcement at the desired locations prior to forming the blank into tubular form.

I claim:

1. The method of forming a tubular member Inthese instances, cergreases sired shape to said first portion and to remove the lateral marginal portions of the end portion to provide an end portion of less width than the original strip of metal with parallel edges and merging with the said first portion of the blank on a gradual taper, rolling the blank into tubular form about an axis extending longitudinally of the blank, and welding the-lateral edges thereof to provide a tube having at one end a reduced diameter end portion of greater wall thickness than the portion of the tube contiguous thereto, heating said reduced end portion and immediately after heating subjecting the said end portion to successive combined upsetting and forging operations to impart a final and different form thereto without reheating.

2. The method of forming atapered tubular member having and portions of greater thickness than the intermediate portion and tapering from oneend portion part way of the length of the tube toward the other, which consists of shearing from a band of uniform thickness and of metal, of a width equal to the initial length of a desired blank, a plurality of blanks, each of which is tapered from one of its ends to its other end, said blanks being out from the band with like ends of adjacent blanks being oppositely arranged with respect to each other, whereby they are in nested relation and waste material is eliminated in the cutting operation, roll-forging each blank to reduce the thickness thereof at the portion between and spaced from the end portion and to increase the length of the blank, trimmine the edges of the roll-forged blank about an axis extending longitudinally of the blank, to the desired configuration, rolling the entire blank into tubular form and Welding all the lateral edges thereof to form a tube tapering from adjacent one end toward the other end and having its smaller diameter end portion of greater wall thickness than the tapered portion, heating said end portion and then subjecting the said smaller end portion to successive combined upsetting and forging operations, without reheating, for imparting the final configuration required to the thickened wall portion,

3. The method of forming elongated tubes with thickened and flanged end portions, comprising roll-forging an elongated sheet metal blank of approximately uniform thickness throughout its area, but of less thickness than desired for the end portion, to thin the same across its entire width and while leaving an end portion unreduced in thickness, trimming both side edges of the forged blank, bringing the side edges together and welding them to form the tube, then heating the thick-walled end portion of the tube and CERTIFICATE OF CORRECTION.

Patent No. 2,196,L|.97.. April 9, 19140.

HOMER n. HIEHAN.

It is hereby certified that; error appears in the printed specification of the above numbered patent requiring correction asfollows; Page )4, sec- 0nd column, lines 11.5 and 14.6, claim 2, strike out the words and comma "about an'axis extending longitudinally of the blank," and insert the same after "form" in line 148, same claim; and thatthe said Letters Patent should be read with'this correction therein that the same may conform to the record or the case in the Patent Office.

' Signed and sealed this hen day. of June, A. D". 191m.

. Henry Ven Arsdale, Acting Commissioner of Patents.

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