US2603175A - Method and means for making wrought fittings - Google Patents

Description

July .15, 1952 Filed Aug. 25, 1947 P. D. WURZBURGER METHOD AND MEANS FOR MAKING WROUGHT FITTINGS 5 Sheets-Sheet l IN VEN TOR.

PAUL 0. WURZSURGER BY j T M) 14 TTOR/VE Y5 y 1952 P. D. WURZBURGER METHOD AND MEANS FOR MAKING WROUGHT FITTINGS 3 Sheeft-Sheet 2 Filed Aug. 23, 1947 IN VEN TOR.

PAUL 0. WURZBURGER H TTORNE Y5 J y 15, 1952 P. D. WURZBURGER 2,603,175

- METHOD AND MEANS FOR MAKING WROUGHT FITTINGS Filed Aug. 25, 1947 '5 Sheets-Sheet s IN VEN TOR. PAUL 0. WURZBURGER f7 TTORNEYS Patented July 15, 1952 UNITED STATES PATENT- OFFICE.

METHOD AND MEAN S FOR MAKING WROUGHT FITTINGS Paul D. Wurzburger, Cleveland Heights, Ohio Application August 23, 1947, Serial No. 770,293

Claims. (Cl. 113-44) form the'desired hollow branch fitting. In such a forming process the volume of the resultant fitting is smaller than the volume of the original blank. At least in part this shrinkage in volume is due to the tendency of the metal walls to become thicker.

When such a diminution in volume of a fitting results during the forming operation, the pressure of the filler material, which is usually virtually incompressible tends to increase beyond bounds. The result is the bursting strength of the fitting is exceeded and any unsupported portion of the blank tends to rupture. This can be obviated by relieving the pressure of the filler material before it can reach this upper limit.

Several methods of the prior art attempt to provide for pressure relief by permitting liquid filler material to escape from the partially wrought blank by means of preloaded relief valves. Because of the inertia effects inherent in such a method of pressure relief, the internal fiuid pressure is subject to undesirable and abrupt variations, making control of the forming operation difiicult if not impossible. Delayed pressure relief invites momentarily high pressures which often are destructive; over-relieving results in loss of pressure when the same is needed for proper forming of the fitting. The surges in pressure resulting from the use of relief valves are therefore to be avoided if consistently satisfactory results are to be achieved.

Another proposed solution to the problem suggests the use of a plastic filler material of high viscosity such as lead with a provision for pressure relief by permitting excess material to escape from the blank through a perforation in the wall, such perforation being located where the end of the lateral branch is to be formed. This expedient is disadvantageous in commercial production for the loading of such a perforated blank is inconvenient, and, what is more important, it is very difficult to maintain correct internal fluid pressures when a portion of the filler material can escape outwardly without an opposing pressure to set a lower limit to the internal filler pressure. Another drawback to the. use of a perforated blank is that the perforation tends to tear, especially if the edges are ragged, causing injury to the fitting and complete loss of control over the forming operation.

Yet another proposal to meet the problem of diminishing volume is to prevent wall thickening by supporting the blank positively during the forming operation by internal supporting plugs. This proposal is impracticable for commercial production; for, first, it'is difiicult if not impossible to prevent thickening of the wall of the blank at the zone where the intercommunicating branches intersect. Secondly, if loosely fitting plugs are used the metal will first thicken to fill the clearance between the plug and the blank, and thirdly, the use of closely fitting plugs presents difficulties of insertion into and removal from the blank.

A general object of my invention is to provide methods and means for forming hollow tubular fittings such as T-fittings or the like in which the difficulties of the prior art described above are substantially overcome. It is therefore among the objects of my invention to provide a method for making such fittings out of tubular stock by creating desirable internal filler pressures in the blank throughout the forming operation. More specifically it is an object to provide that the rate of displacement of filler material be kept in harmony with the rate of change in volume of the blank or piece during the working operation as by working the filler at a rate in relation to the rate of working the piece that is proportional to the rate of diminution of volume of the blank from initial to final form.

Another object is to provide a filler material of novel and advantageous properties which can be handled, inserted into and removed from the work piece and/or can be precompressed in the work piece and which is readily soluble in water; which has a low melting point so that no problem of amalgamation or cleaning is involved and which has desirable lubricating and viscosity properties.

Another object is to provide a body of substantially incompressible plastic filler material having preformedvoid spaces which facilitate a controlled diminution'in filler volume during the forming of the fitting so that a substantially constant and desirably high internal filler pressure can be developed and maintained.

These and other objects and advantages of my invention-will more fully'appear from the following description of certain preferred and modified forms-thereof reference being had to the accompanying drawings in which: Figure 1 is a longitudinal sectional partially fragmentary and partially diagrammatic view of a tubular blank and forming apparatus at the beginning of the forming operation according to a preferred form of my invention; Figure 2 is a view similar to that of Figure 1 showing the end of the forming operation; Figure 3 is a diagrammatic view of an arrangement of the forming apparatus; Figure 4 is a view similar to Figure 1 of a modified form of my invention with the apparatus showing the beginning of the forming operation; Figure 5 is a view corresponding to Figure 4 showing the end of the forming operation; Figure 6 is a view similar to Figure 1 of another form of my invention with the apparatus at the beginning of theforming operation; Figure '7 is a view corresponding to Figure 6 at the end of the forming operation; Figure 8 is a view similar to Figure 1 of another modified form of my invention with the apparatus at the beginning of the forming operation; Figure 9 is a view corresponding to Figure 8 showing the parts at the end of the forming operation; Figure 10 is a transverse sectional view taken along the lines 10-40 of Figure 8; Figure 11 is a view similar to Figure 1 of another form of my invention showing the parts at the beginning of the forming operation; Figure 12 is a view corresponding to Figure 11 showing the parts at the end of the forming operation; Figure 13 is a transverse sectional view taken along the lines l3--l3 of Figure 1, and Figure 14 is a view similar to Figure 13 showing a modified form and construction of filler material.

Exemplary forms of my invention contemplate forming branch fittings by applying forming pressures directly upon the end of a tubular blank and also applying pressure upon substantially incompressible filler material confined within the blank in relative amounts and rates which produce desirable flow and working of the metal. I prefer that filler material pressures will remain desirably high but below the bursting strength of the blank adjacent the weakest point thereof. Also I prefer that a preliminary pressure be built up in the filler material prior to the exertion of metal flowing pressure upon the ends of the blank so that the filler material will tend to act incompressibly during the working of the blank. Precompression of the filler may also tend to stress at least that portion of the blank adjacent the branch to be formed before or possibly simultaneously with the working of the blank in response to pressure exerted directly upon the ends thereof.

Throughout the following description and illustration of preferred and modified forms, embodiments and practices of my invention specific reference is largely confined to the making of the T forms of branched fittings, and the same is not to be taken by way of limitation but rather by way of exemplification of the principles of my invention as the same may be applied with like facility to the making of crosses and'other branch forms not so specifically illustrated and described.

Referring now to Figures 1, 2 and 3 of the drawings the tubular blank I preferably in the rightcircular cylindrical form of the metal or alloy to be worked is disposed in the sectional die 2, one half only being shown, which with its companion half not shown provides a suitable T-shaped channel 4 comprising a head portion 5 and a lateral branch or leg portion extending at right angles thereto; the tubular blank I being initially disposed in the head portion 5 of the channel as shown in Figure 1. The die may be divided along any one of several parting lines but I find it advantageous to split it longitudinally and symmetrically as shown, using centering pins 3 to align the separate halves, although the die might be split through the head portion of the channel in a plane normal to the branch 6 substantially along the line 8 as suggested in Figure 3 if that were desired.

The tubular blank preferably comprises workable metal such as fairly soft copper. aluminum. mild steel or other metals or alloys which will flow easily and which are extrudable under the influences and conditions to be hereinafter more fully set forth. The efficacy of my invention admits of the use of other desirable metals and materials, the working of which has been regarded as too difficult for practicability. It will be understood that the split halves of the die 2 may be opened and closed to permit the insertion of the blank I in the first instance and the removal of the wrought piece P by suitable opening, closing and clamping mechanisms which are known in the art but which are not specifically shown herein. The wrought piece P is shown in Figure 2 at the completion of the working thereof; the ends of the tubular blank I having been forced toward each other and the branch or leg l0 having been forcibly extruded into the branch channel 6 of the die as a result of the working presently to be more fully described.

As indicated above the practice of my invention includes the employment of filler material ll disposed interiorly in the tubular blank I in the first instance and thereafter forcibly constrained to flow from its original position into the leg portion I0 of the piece as suggested by comparison of Figures 1 and 2. The filler material that I prefer to employ is characterized by its ability to flow or spread under pressure by that degree of fluidity, elasticity or viscosity most suitable for Working different metals or alloys for the practice of the different forms of my invention presently to be described and by the ease with which it may be formed for use with the tubular blank and the ease with which it may be removed from the work piece. While I do not disclaim the use of filler materials ranging from liquidsto lead, lead alloys, Woods metal, wax and the like in the practice of specific forms of my inventionfor such specific utility-as may be had from such filler materials, my preference is to use one or another of the polyethylene g'lycols or mixtures thereof having the characteristics of fluidity, viscosity, strength or weakness that coacts most efliciently in the form of method employed and with the 'material to be worked.

The polyethylene glycols of the general formula HOCH2(CHzOCHz)2+xCHzO-H having molecular Weightsof the order of about 1000 to about 7000 are wax-like solids whose melting points and viscosity increase substantially in proportion to their molecular weights and whose solubilities in water or organic solvents are roughly inversely proportional to their molecular weights. Polyethylene glycol having an average molecular weight of about 3000 is hard translucent waxlike solid somewhat resembling paraffin wax in appearance and texture, which is soluble in water and which has a melting point around 50 C. When its molecular weight is increased to between 6000 and 7500 the melting point increases to about 58 to 62 C. It is still soluble in water and its viscosity is substantially inof reasons.

creased. Below an average molecular weight of about 700 the polyethylene glycols are liquids at room temperature. Within this range of choice from among the polyethylene glycols and mixtures thereof a number of advantages persist, namely, the fact that the filler may be very easily removed from the finished work piece by virtue of its solubility in water or other solvents at room temperature or alternatively by melting the filler at low temperatures which are harmless to the metal of the finished piece. Moreover the polyethylene glycols do not tin the interior of the work piece nor do they leave insoluble residues which must be removed as by de-tinning, de-greasing or de-waxing as is often the case with other known filler materials. Moreover the polyethylene glycols particularly in the range of molecular weights from about 1000 to 7000 have advantageous lubricating qualities which assist in the extrusion operation and facilitate the flow of metal and the flow of the filler material during the working of the blank. The filler material of my preference may be cast directly into the blank or the midportion thereof as shown in Figure 1, or alternatively it may be pre-cast or otherwise formed into slugs or pellets of a desired size with or without internal voids, see Figures 8 to 12, suit able for manual insertion into and fit within the tubular blank.

As shown in Figures 1 and 2 I prefer to employ a quantity of filler material II not greatly in excess of the volume of the lateral branch or branches that are to be extruded or formed from the tubular blank such as the branch or leg I0 shown in Figure 2. I find it desirable to use a minimum volume of filler material sufficient to fill substantially only that middle portion of the blank which is to be worked rather than any greater portion of length for a number Firstly, the cost and expense of handling and recovering filler material is reduced. Secondly, it is practicable and at all times advantageous to support those portions of the blank which are not worked or not substantially worked by rams such as the rams I3 and I4, shown in Figures 1 and 2, which have a close sliding fit with the internal surface of the blank and constrain these so-called unworked portions of the blank to their desired size and shape more efficiently in many instances than filler materials whose characteristics may best be selected for the specific purpose of working the work parts of the material of the finished piece. Moreover by using substantially the minimum volume of filler material, I am able to create and maintain a much more nearly uniformly desirable pressure throughout the whole of the filler material than would otherwise be the case especially where it is desirable to use a filler material of high viscosity in which a large pressure gradient would be developed between the ends where pressure is applied by the mandrels and the mid-portion where pres sure is sought to be developed between the filler material and the portion of the blank to be worked.

In this preferred form of my inventionl provide two oppositely acting hollow plungers I9 and arranged to engage the opposite ends of the blank I and exert the necessary forming and extruding pressures thereupon. Preferably those portions of the ends of the plungers I9 and 20 that enter, the ends of the head part 6 of the channel of 'the die have a close sliding fit therewith and these portions of the plungers preferably have a wall thickness substantially equalto the wall thickness of the tubular blank I. 1 The hollow plungers I9 and 20 have straight cylindrical bores 2I- and 22 of approximately the same diameter as the internal diameter of the blank I within which bores, rams I3 and I4 are independantly slidably movable in a close sliding and mutually supporting fit therewith. The rams I3 and I4 valso have a close sliding fit with the interior of the blank of the work piece wherewith to be movable thereinto and, in the first instance, Figure l, engage the filler material between their opposed ends and at all times confine the filler material to the space between their opposed ends in the middle portion of the blank and/or the extruded leg as the size of that space is determined by the position and movement of the rams I3 and I4 independently'of but more or less contemporaneously with the movement of the plungers I9 and 20.

As shown diagrammatically in Figure 3 fluid motors 24 and 26 are operatively connected with the plungers I9 and 20 respectively for efiecting and controlling the movement thereof and fluid motors 21 and 28 are operatively connected with the rams I3 and I4 respectively wherewith the rams and the plungers may be given whatever independent or correlated movements and forces are desired. Means not shown are preferably provided to insure that the plungers I9 and 20 move toward the center of the die 2 at substantially the same speeds and through the same distances while working on the ends of the branch I and the strokes of the plungers I9 and'20 are centered up with respect to the die 2. wherewith the plungers will move symmetrically and simultaneously with respect to the transverse center of the di and will center the blank if the same should be placed in the die asymmetrically before the forming operation. The'cylinders of the fluid motors 2! and 28 may be mounted on fixed supports or as suggested in Figure 3 may be carried on the remote ends of the plungers I9 and 20 and be movable therewith; the rams I3 and I 4 being connected with the pistons of the motors I 21 and 28 whereby to have movement independently of the plungers I9 and 20. The cylinders of the motors 24 and 26 are mounted on fixed supports and the pistons thereof are preferably directly connected to the plungers I9 and 20. Preferably liquids are employed in the motors 24 and 26 and appropriate hydraulic mechanisms and connections not shown provide for the proper admission and discharge of fluid from the opposite sides of the pistons to obtain forcible forward and backward motions of the plungers l9 and 20 as may be desired to carry out my method. Preferably the motors 21 and 28 are pneumatic and with the aid of accumulators 29 and 30, and appropriate connections and control mechanisms not shown, may be caused to provide substantially constant pneumatic pressure on the rams I3 and I4 for their forward strokes and such pressures as may be desired for the withdrawal strokes thereof in the sequences presently to be described.

The blank I being disposed in the head portion of the channel of the die as shown in Figure 1 and the die head being closed, theends of the plungers I9 and 20 in their initial inward movement engage the ends of the blank I whilst the rams I3 and I4 engage the opposite ends of the body or plug of filler material II, as shown in Figure 1, completely confining the filler materialin the first instance and throughout the 7 whole of the forming operation. 'As mentioned above, I prefer that the rams l3 and I4 begin to compress the filler material slightly before the power is applied to the plungers ISand 20 to begin the working operation. The parts being substantially in the position shown in Figure 1 with the rams compressing and confining the filler material and developing therein that pressure which may be substantially maintained throughout the whole working operation, power is then applied to the plungers l9 and 2!] sufficient to cause the metal of the walls of the blank to flow toward the middle thereof and into the leg branch 6 of the die until the desired amount of extrusion of the middle branch I!) of the work piece has taken place, see Figure 2. During the working strokes of the rams and plungers the speeds and movements of the pair of rams toward each other as well as the speed and movements of the pair of plungers toward each other will preferably be uniformly the same, but the relative speeds of the rams in relation to the plungers will be different so that the flow of filler material from the blank or head portion of the T into the extruded branch will never develop a deleterious high pressure nor fall below an advantageous working pressure. The average rate of inward movement of the rams will be less than the average rate of inward movement of the plungers in the same proportion that the volume of the finished work piece P bears to the volume of the blank I. Reference to the average rates of movements or speeds of the rams of the plungers from the beginning to the ends of their working strokes contemplates that within the working strokes their particular and instantaneous speeds may depart from their average speed since at different times within a working stroke the rate of change in the volume relationship may vary and tend to create changes in pressure in the filler material. However, I have observed that it is practicable to give the rams and plungers respectively substantially constant pre-determined relative speeds for their working strokes at the relative rates above mentioned as by positive linked or geared interconnection, not shown. I prefer, however, that the plungers be given the force and power required to cause the metal to flow with desirably high speed while the rams be caused to exert upon the filler material that substantially constant high pressure safely short of a bursting pressure; the summation of the efforts of both rams and plungers thus being a minimum in respect to the work that is done, i. e., the metal is worked with the least gross effort and in so doing the relative average as well as the relative instantaneous speeds of the rams compared to plungers approximates the ratio of the final volume of the piece P to the initial volume of the blank I. Influencing the rams and plungers to have the movements and to exert the pressures mentioned above taken with the employment of a desirably small mass of filler material and with the confinement of the whole mass of filler material between the ends of the rams, not permitting any of the mass of filler to escape or be relieved from its conflnement nor be subjected in any part to substantially less than the desired pressure during the whole time of working the piece, gives, as I have observed, most satisfactory results in a number of respects which taken collectively enhance the product and facilitate the working and making thereof. Thus the initial and continued uniform collaboration of the filler material in the work'- 8. ing operation resists undesirable tendencies oi incipient tendencies of the metal to wrinkle, thicken, thin out, burst or shear as it might and often does where the filler material is not caused to play its full and best part in relation to the forces and movements given to the ends of the blank to effect the direct working thereof by the plungers.

In this form of my invention I find it practicable to employ polyethylene glycol of the lower range of molecular weights mentioned above, 1. e., of lesser viscosity since the desired flow and action of the filler material in the piece is largely characterized by the qualities of a liquid. In fact I have found it not impracticable in some instances to employ a liquid for a filler material in connection with this form of my invention, introducing liquid filler through a drilled hole 3| that may be provided for such purpose in one of the rams [3 as shown in dotted lines in Figure 1 when the parts are in substantially the position shown in Figure 1 whereupon the passage 3| would be positively closed to hold and contain the liquid filler material in the same space occupied by the plastic filler material H so that the liquid so introduced would play the same part and do substantially the same work in the same way as the plastic or relative solid filler material in the above described sequence of events. In other forms of my invention to be described below a higher 'viscosity of filler material appears as presently advised to be more desirable for reasons which will therein more fully appear. In the suggested use of liquid or low viscosity fluid filler material in the preferred form of my invention it is prudent to gain or preserve the advantages of my invention to modify the sequence of the initial application of force and movement to the rams and plunger-s respectively so that the wall of the blank surrounding the ends of the rams will have been compressed and thickened a little to effect a substantially fluid tight seal before fluid pressure is built up in the liquid filler that would induce a deleterious amount of leakage of filler from the blank prior to and/or in the beginning of the working strokes of the rains. Modifying the initial sequence in this way facilitates the preservation of the same or substantially the same function, mode of operation and results with respect to the work and action of the filler as that above described wherein the viscosity of the filter was taken to be such that its leakage would be negligible when the rams first developed a substantial pressure thereupon and therein prior to the thickening of the walls by the plungers to more effectively seal the space or clearance between the ends of the rams and the ends of the blank.

In this preferred form of my invention and as indicated in Figure 2 the stroke of each of the plungers from the beginning to the end of the working operation will comprise the distance SI and the stroke of each of the rams during the same interval and operation will comprise the lesser distance S2. Since the outside diameter of each of the rams is substantially equal to the inside diameter of the blank the displacement of volume of the blank is a direct function of the stroke SI of the plungers and the displacement of filler material is a direct function of the stroke S2 of the rams. Thus to carry out my object that the displacement of filler into the extruded leg be not excessive but on the contrary be at such a beneficent and/or rela- 9 tively diminished rate in comparison with the reduction of the length of the blank, i. e., the head portion of the piece, as to preserve the extruded leg of the piece against bursting I cause the stroke S2 of the rams to have the same a proportionate relation to the stroke SI of the plungers as the volume of the finished work piece P bears to the original volume of the blank I. That is to say,

2 internal volume of piece P S 1 internal initial volume of blank 1 the part of the blank lying in the head of the channel of the die, i. e., the rate of reduction of volume of .the head of the T as the volume of the finished piece P is to the original volume of the tubular blank I. [By either definition, as-

suming that the working strokes of the rams and'plungers respectively begin at the same time and continuethroughout the same interval of time, then as above mentioned the average speed of the rams is to the average speed of the plungers as S2 is to SI in all cases where the rams and plungers both displace the same crosssectional area of volume of filler and volume of tubular blank respectively.

The change or reduction in the volume or cubical content of the blank or work piece does not necessarily take .place at an exactly constant rate during the working of the piece. No

doubt more specific factors enter into the differences between the instantaneous rates of change of volume than I am now aware of or could profitably speculate aboutwithin the confines of this specification. Mention of a few factors will illustrate the point. For example, where the ends of the rams extend for a long distance inwardly of the ends of the blank, as shown in Figure 1, and have a snug fit with the internal surface of the blank throughout a large portion of the internal area thereof, and assuming that the external surfaces of the blank are also snuglysupported in the channel of the die, these things will greatly limit or reduce that part of the loss of volume arising from the thickening of the walls of the blank especially at and adjacent the ends thereof where the ends of the plungers bear thereupon. Insofar as this rate of loss of volume tends to be rapid at thebeginning of' the working stroke of the plungers, this factor is much diminished in this preferred form of my invention. It may be mentioned in passing that the initial disposition of the ends of the rams as far as practicable into the blank consistent with the desired volume of filler material for the branch or branches to be extruded, goes hand in hand with the advantage and desirability of employing the minimum practicable volume of filler material.

Another factor bearing upon the instantaneous rate of change or reduction in volume of the piece is-the sharpness of the corners of the intersection between the head and branch leg; the sharper and more abrupt corners tending to thicken up more than the more rounded and less abrupt corners around which the metal of the blank is caused toflow. This thickening or tendency to thicken takes place, as I believe, somewhat later in the stroke than the tendency to thicken the ends and is much reduced by the continuous and beneficent participation of the filler material in the working of the metal. Other -10 factors, as I believe, are related to the softness, ductility and other physical characteristics of the stock of the blank as well as to the absolute speed with which the work is done. On the whole my invention tends of itself, for some or all the reasons above mentioned, and as hereinafter will more fully appear, to cause the rate of reduction of volume of the piece to be substantially uniform or more uniform than prior practice throughout the working stroke and also tends tocausethe diminution or change in volume of the piece from tubular blank to finished form to be small or relatively small compared withprior practices,- For these reasons it is practicable as mentioned above to drive the rams and plungers positively at'predetermined rates of speed but because of variations in stock, working conditions and other things not always predictable I prefer to drive the plungers substantially positively and to drive the rams by exerting thereupon substantially uniform and'constant pressure wherewith toexert substantially constant pressure on the-filler and hollow plungers 34 and 35 similar in essential respects and functions to the plungers l9 and 20 of the form of Figures 1-3 and operated in substantially the same way, but differing in structure in that they are provided with walls -of greater thickness than the thickness 'of the :wall of the blank! whereby to be stronger thanthe plungers l9 and 20. Plungers 34 and 35*have pilot portions 40 and 4| respectively which extend into and closely fit the interior of the-blank to support to the end portions of the blankinternally while shoulders 31 and 38, which mark the juncture of the pilot portions 49 and 4lwith the body of the respective plungers engage the ends of the blank. Since the outside diameter of the plungers is substantially the same as the O. D. of the blank, both blank and plungers fit snugly within the head recess 5 of the dies '2. The pilot portions fit snugly within the ends of the blank and the dimensions andarea of the shoulders 31 and 38 are the same as-the end faces of the blank. Rams 44 and 45 slide within the boresof the plungers 34, and 35 respectively and preferably in initial position take substantially the positionshown in Figure 4, i. e., with their end faces 46 and 4! flush with the'end faces 42 and 43 of the pilot portions of the plungers respectively wherewith to bear collectively on the square end of the right cylindrical slug of filler material.

In its general features of operation this modification is similar'to the preferred form described above. Thusthe plungers 34 and 35 are preferably adapted to be moved simultaneously toward each other and to contact-the'blank and correctly position it within the die before the forming takes place.' Preferably also the rams 44 and 45, which again are independently movable with respect to the plungers, preferably impose a desirable preliminary pressure upon the filler material II which is confined within the blank, just prior to the beginning of the. forming operation. It will be noted that one of the main through their shoulders 31 and 38; but also through the end faces 42 and 43 ofLtheir-pilot portions also impose-pressure on and displace filler material it. The rams 4'4 and 45 in this instance thereforedo not have the whole burden of displacing filler material but share it. with the plungers. For the-same reasons the rate of displacementof filler material is not a direct and solefunction of ram speed and movement but rather: depends upon the speeds and movements ofboth the rams and plungers. Therefore. while the plungers 34 and 35'move through a stroke 8|, shown in Figure 5, equal to the stroke SI, shown in Figure 2, the rams 44 and 45 will have moved through a strokeS3: which will be smaller than the stroke S2, assuming that the blank I and thefinishe'd piece-P are respectively the same inboth instances:- The amount by which the stroke s3 is less than'the stroke S2 isproportionate'to the relationship of'the size of the rams l3 and 4 to thesmaller sizes of the rams 44 and 45; and this follows from the fact that in the modification shown in Figures 4 and 5v the net displacement of filler material is a function of the difl'erenti'al between therate. of displacement offiller by the end areas of the ends of the pilots of the plungers and the end areas of the ends of the rams. Thus the stroke and average speed of the rams in this modification is to the stroke and average speed of the plungers as the volume of the finished piece P, less the volume of filler material displaced by the plungers, is to the initial volume of the blank I. It will thus be seen that the stroke and movement of' the rams, in this modification, being a function of the relative effective filler displacing area of the end faces of the rams compared to the effective filler displacing area of the end facesof the plungersmay, depending on the relation of these-areas and the net change of volume between the blank and the finished piece, lie-specifically greater or less than S3- as shown and may be zero or even be negative to fulfill the teachings and precepts of my invention. Underall circumstances, however, whether the rams move much or little or'positively' or negatively the rams always exert a desir-able and/or desirably high and continuous pressure-on the filler material substantially from the beginning throughout and to. the end of the working stroke of the plungers" wherewith to maintain the maximum useful pressure in and throughout the filler material to cause it to play substantially the same useful part in the working of the piece in substantially the same way described more fully in respect to the preferred formof my invention. That is to say, the quantity of filler material initially engaged between theends of the rams and the ends of the plunger pilots wil1 be completely confined and worked and subjected to a continuous substantially uniform pressure and induced to flow into the extruded branch- IU of the piece at the most desirable rate and under the most desirable substantially con-- stant pressure.

When the areas of the ends of the rams are such in relation to areas of the ends of the pilots that the rams may exert their pressure on the filler-without movement while the pilots displace the: proper'volume of filler material at the desired rate into the extruded leg, then the areas of the pilots may be expressed in the proportion: Cross-sectional area of filler material displaced by ends of pilots is to the whole internal crosssectional area of the blank as the volume of finished piece P is to initial volume of the blank I. The areas of the rams thereupon equals the difference between the cross-sectional area of the 12 blank and the areas of the ends of the pilots. In this relationship the ends of the rams theoretically might initially'be brought into end to end contact in the middle of a hollow slug of filler and remain insubstantial contact throughout the working strokes since the pressure on and in the filler and the flow and displacement thereof in- "duced by the pilots will substantially correspond to the intended optimum to facilitate working the piece without injury thereto; the filler material being entirely confined and held under a desirable pressure throughout the working stroke and none of the filler material being urged or permitted to flow other than in the direction. of extension of metal toward and into the leg being formed. As will more fully appear below 1 have observed the mechanical problem. of, supporting the free ends of ramstransversely in the stream of. flow offiller. material to the leg of a T and therefore refer tothe. above procedure as theoretical. except in the instance of making crosses or other forms where the flow of filler transversely of the exposed end of rams is symmetrical.

The modified form of my invention shown in Figures 6 and 7 departs from the preferred form shown in Figures 1 and 2 in that while the hollow plunger 54 with the ram 55 may be substantially identical with the plunger 20' and ram l4, the oppositely disposed plunger 50 has an integrally formed pilot 5| extending into the blank I and closely fitting the interior of the blank and preferably occupying substantially the same position within the blank as the end of the pilot l3 in the initial working position, of. Figures 1 and 7. In this modification the pilot portion 5| of the plunger 50 terminates in a square annular shoulder 52, the shoulder having a radial depth substantially equalling the thickness of the stock of the blank wherewith the plunger 50 will engage the right end of the blank through the shoulder 52. Preferably the pilot portion extends into the blank as far as practicable consistent with the length of the leg Hi to be. extruded and the pilot terminates in a forwardfiller engaging face 53. The plunger 54 with the ram 55 independently movable therein is intended to be moved equally and oppositely of the plunger 50; the plungers 54 and50 engaging the ends of the blank I and forcing the metal to flow in substantially the same way that the plungers i9 and 20 illustrated in Figure 1 act upon the metal of the blank. In this modification, however, the filler material H is engaged and, confined between the end face 53 of the pilot 5| and the end face 55 of the ram 55 wherefore all of the compensation for the diminishing volume of the piece during the workingv thereof is effected by the proper differential speeds and movements between the single ram 55 and the hollow plunger 54. Inasmuch as the stroke of the pilot 5| is the same as the strokes SI of the plungers, the stroke S4 of the ram 54 will be less than the stroke S2 of each of the rams l3 and I4 by an amount which is substantially twice the difference between the strokes Si and S2 for the plungers i9 and 2!! and the rams I3 and M respectively. In this form of my invention it is practicable to drive the plungers positively as by the hydraulic motors 24 and 25 shown in Figure 3 and to drive the ram 54 as by the pneumatic motor 28; preferably, as in the preferred form, maintaining a substantially constant maximum desirable pressure on the ram 54 from the beginning throughout the working stroke of the plungers. This form of my invention permits substantially the same operation and results as the preferred form and saves the employment of one of the motors or mechanisms for driving one of the independently movable rams.

Another modified form of my invention is ilthe operation of the modification shown in Figures 4 and 5 it was mentioned that if the rams were of proper size and cross-sectional area that they might be required to have no movement during the working of the piece and/or might be maintained in end to end contact within the mass of filler material throughout the working of the piece while preserving the characteristics and mode of operation of my invention and the desired pressures in the filler material and the desired flow thereof into the extruded branch. In the modification shown in Figures 8, 9 and 10 the plungers 60 and GI with their pilot portions 62 and 63 may correspond in external configuration substantially to the plunger 50 shown in Figures 6 and 7 with square annular shoulders 61 and 69 engaging the ends of the blank I; the plungers 60 and 6| preferably being driven inwardly of the channel 4 of the dies 2 in the same way and by the same means that the plungers in the preceding forms have been described to be operated. In this form of my invention, however, the block or slug of filler material 72 instead of being a true solid right cylindrical block in the first instance has a substantially cylindrical external form filling the interior of the blank 5 as shown in Figure 8, but has a small preferably cylindrical channel 13 formed or molded on the lower, as viewed, side thereof, see Figure 10, within which is disposed in the first instance a pin 14 which fills the channel '53 and extends the full length of the filler material and when the plungers 60 and SI are in the starting position shown in Figure 8 has its ends 16 and '11 extending into closely fitting drilled holes lil and H in the lower, as viewed, portions of the pilots and plungers. The holes 10 and H in the plungers closely fit and receive the ends of the pins '14 wherewith to permit the ends of the pin to enter the holes to the exclusion of filler material when the plungers exert pressure on the filler material. Thuswhen the plungers move inwardly toward each other the end faces 65 and 66 thereof which bear upon and compress the filler material do not have the full circular cross-sectional area of the internal diameter of the blank to present to and displace filler material, but rather have an eifective working area for displacing filler material which equals the cross-sectional area of the blank, or the pilot, less the cross-sectional area of the pin M. Therefore I provide that the diameter of the pin M- be such that its cross-sectional area when subtracted from the cross-sectional area of the inside of the :blank will leave an area which is to the whole cross-sectional area of the blank as the volume of the finished piece P is to the volume of the original blank I. That is to say the volume of the ends of. the pin 14 that is received in the holes 10 and H during the working stroke of the plungers will substantially equal the loss of volume in changing the tubular blank I to the form of the finished piece P. In the operation of this form of my invention the slug of filler material 12, which preferably is of the range of higher viscosity of the materials above mentioned, is long enough to completely fill the interior of the blank between the end faces 65 and 66 of the pilot portions of the plungers just at or very slightly prior to the time when the shoulders 61 and 69 engage and begin tocompress/the ends of the blank. At the same time the ends 16 and 11 of the pin M will have entered the holes Hi and H "wherewith all the space within the blank between the ends of the plungers is occupied and completely filled either with, displaceable filler material '12 or the nondisplaceable pin 74. Preferably the initial increment of movement of the plungers 60 and 6! will develop a desirable initial pressure in the filler material safely lower than the burst n strength of the blank and sufiicient to aid in the initial swelling out and extruding of the branch 10. Thereafter succeeding increments of movement of the plungers towardv each other will force the ends of the blank toward each other and induce the extrusion of the metal of the blank into the branch 6 of the channel of the die and at the same time will displace filler material into and in the direction of flow of metal into the extruded leg of the piece at a rate which for the reasons mentioned above will not create excessive high pressuresin the filler material nor rupturing strains in the metal of the piece but will be high enough to facilitate the working of the metal and the desirable formation of the extruded branch H] in much the same way as the same is accomplished in the preferred form of my invention first above described.

It will be observed that the pin 14 is disposed at the bottom, as viewed, of the slug of filler material diametrically opposite and removed from the branch to be extruded. I have found it desirable if not necessary to so dispose the pin particularly in the extrusion in the leg of a T fitting whereby to keep the pin out of the transversely moving stream of the viscous filler material to avoid bending the pin during the working operation. For like reasons if the blank were to be worked into the form of a cross fitting rather than a T so that the flow of filler material into oppositely disposed branches would be symmetrical with reference to the axis of the blank, then it would be desirable to dispose the pin coaxially of the blank and of the plungers.

It will be appreciated that the pin 14 might conveniently be secured in one of the plungers at one end whilst being free to slide in a hole like either of the holes 18 or H in the other of the plungers without changing the operationl It will also be noted that I prefer, as shown in Figures 8 and 9, to bleed the ends of the drilled holes 10 and H to atmosphere to facilitate freedom of movement of the ends of the pin 14 therein substantially equal to the shrinkage in volume of the fitting which takes place during the forming process. The slug 9!) may be cast solid and the bore drilled or punched out or the slug may be extruded in the form of a tube and then cut to proper length, or formed by any other suitable method depending upon the filler material selected and on the relative convenience of the several methods. As suggested in Figure 14 the slug 90' may be cast or otherwise formed in two longitudinally split halves which when assembled will define the voided bore SI of the desired size, or may be cast to define when assembled one or more spherical or other shaped voids. While I prefer to provide a single cylindrical void or bore in the slug of filler material my purpose admits of other forms and numbers of voids so long as the desired function and operation of the voided filler is preserved. It is mentioned for illustration that a filler slug having a plurality of small spherical voids will tend to resist reduction of gross volume to better advantage than a slug having one cylindrical void of the same volume. As mentioned the volume or reduceable volume of void is substantially equal to the loss of volume occasioned by working the blank I to the form of the finished piece P, but the mere provision of any void or voids in or adjacent any filler will not necessarily support the other purposes and objects ,of my invention in creating and maintaining desirably high and substantially unifrom pressure in the filler while accommodating the diminishing volume of the piece wherewith to facilitate the working of the piece and the flow and extrusion of metal into the extruded branch or branches. To this latter end the shape and disposition ofthe void or voids taken with the strength and viscosity of the filler material when regarded as a structural element resisting collapse under longitudinal compression, permits me to develop in the filler material the desired high pressure, prevent the pressure from exceeding a desired maximum and atthe same time reduce the gross volume of the filler. For example if one employs polyethylene glycol of a high molecular weight or uses Woods metal of substantially the same strength and uses a single longitudinal void of a .10 diameter in a slug of a given size and otherwise suitably proportioned to carry out my invention, such a slug so voided might well develop a desirable pressure to facilitate the extrusion of a blank of thin walled soft copper. However, all other things being equal, and the blank being made of a tougher material such as stainless steel wherein higher pressure is sought to be'developed in the filler prior or incident to the collapse or reduction in the void or voids then it would be practicable to develop the higher pressure by using two smaller, spaced longitudinally extending voids each of approximately .07" in diameter wherewith to provide the same volume of void but to have a higher resistance to collapse or constriction than the single larger void of like volume. As will presently appear and as is suggested in Figure 12 the compression upon the ends of the voided filler material is accompanied by the flow of filler material in the direction of the extruded branch whereby the material of the filler which defines a'longitudinal void is induced to flow transversely thereof, thereby contributing to the collapse of the structure defining the void and the reduction of the volume occupied by the filler material and/or the filler material plus the voids therein.

16 Referring further to Figures 11 and 12 the voided slug of filler material 90, which preferably closely fits the interior of the blank I, is disposed between the end faces 86 and 81 of the pilot portions of plungers 80 and BI which may be substantially identical with the plunger 50 above described; the plungers having respectively square annular shoulders 82 and 83 which engage the ends of the blank when the plungers are caused to take their inwardly moving forming strokes as induced by such means as have heretofore been described. I prefer that the pilot portions of the plungers and 8| snugly fit the interior of the blank I, and be as long as practicable consistent with the stroke of the plungers, the desired displacement of filler material and the desired length of the slug of filler material which may depend somewhat on the form of the voids provided therein. Preferably the slug 9.0 is compressed between the end 86 and 8'! of the plungers a little prior to the moment of forcible engagement between the shoulders 82 and 83 and the ends of the blank whereby to preload the filler and tend to develop a desirabl high initial pressure a little in advance of the direct working of the metal through the plungers. A following increment of movement of the plungers will begin the inward movement of the ends toward each other and such thickening of the stock as the sides of the pilots and the pressure of the filler permits. As plunger movement continues and as the volume of the piece diminishes pressure in the filler will rise or will have risen to the desired maximum near but below the bursting strength of the piece and at or above the strength of the filler that defines the void or portion of thevoid that is first to collapse or suffer reduction in size under the conditions of working the piece and causing the filler to flow into the extruded branch. Thereafter as the work progresses filler pressure exerted against the piece is maintained and limited within the desired and useful limits specified whilst the gross volume of filler diminishes in accommodation of the diminishing volume of the piece.

In this as in the other forms of my invention I prefer to use a minimum gross volume of filler material consistent with my objects and purposes. In all of the forms and practice of my invention after the leg [0 of the piece P has been formed to its desired length the plungers are withdrawn; the halves of the die 2 separated and the piece ejected. Thereupon the filler material is removed and the closed end of the extruded branch shaped and/or trimmed as may be desired. If polyethylene glycol has been used in the forms which I prefer, its removal from the piece before or after trimming the end of the extruded branch is facilitated by the low melting point or the high solubility of the filler. The T or other branched form of finished piece, i. e., finished with respect to the primary formation thereof according to the instant invention, may thereafter be used directly or worked additionally as by forming sockets in the ends of the branches or otherwise according to known practices.

In all forms of my invention I exact a full measure of service and utility from the filler material in the working of the piece while avoiding the hazard of rupturing or injuring the piece as a consequence of the diminution of the volume thereof as between its initial and finished forms. In all forms of my invention I preserve the desirable differential between the rate of displacement of the ends of the blank toward each other and the rate or displacement of filler material into the branch or branches being extruded, while maintaining on the filler material and between the filler material and the interior surfaces of the piece a desirably high hydrostatic pressure which however is retained below a deleterious value. In all forms of my invention the filler material is continuously confined within the piece and within the diminishing volume thereof and the mass of filler material as a whole is constrained to flow in the direction of the extrusion of the branch or branches wherewith to influence, that extrusion favorably and to aid especially in the working and flowing of the metal around the corners of the intersection of the head with the legs or other branches of the finished piece. In all forms of my invention a desirably high initial pressure is created in the filler material and interiorly of the blank at or prior to the beginning of the direct working of the metal of the blank and the 'beneficently high pressure is maintained continuously and substantially uniformly throughout the whole time of Working the piece; the pressure in and exerted by the filler in and upon the piece never being subjected to sharp changes positively or negatively whether incident to intended relief or merely without control.

While I have illustrated and described preferred and modified forms of my invention and preferred and illustrative means with which the same may be practiced, changes, modifications and improvements therein will occur to those skilled in the art who come to understand the underlying and fundamental principles hereof and the teachings of this specification, and I do not care to 'be limited in the scope of my patent to the form or forms of my invention herein specifically illustrated and described or in any manner other than by the claims appended hereto.

I claim:

1. Apparatus for making a branch fitting such as a T or the like by extruding at least one lateral branch outwardly from a blank of greater volume than the fitting and containing filler material, comprising a die having a main passage receptive of the blank and a lateral branch corresponding to the branch to be formed in the fitting, a pair of oppositely acting plungers, one of said plungers having a longitudinal bore, said plungers being slidable in said main passage of said die with their ends respectively engaging the ends of said blank and engaging and confining all the filler material within said blank throughout the working thereof, a pin disposed in part in said bore and closing the open end of said bore adjacent the filler material and being slidably movable in said bore with a close sliding fit preventing the outflow of filler material through said bore when said filler material is squeezed between the ends of said plungers, said pin also having contact with the other of said plungers and moving in said bore as the ends of said plungers advance toward each other during the working of the piece, means for forcibly moving said plungers toward each other to work the piece and compress said filler material and cause the lateral leg of said fitting to flow into the said branch portion of the die, the volume of said pin entering said bore during the working of the piece being-substantially equal to the diminution of the internal volume of the wrought piece in respect to the original blank.

2. Apparatus for making a branch fitting such as a T or the like by extruding at least one lateral branch outwardly from a blank of greater volume than the fitting and containing filler material, comprising a die having a main passage receptive of the blank and a lateral branch corresponding to the branch to be formed in the fitting, a pair of oppositely acting plungers having longitudinally aligned bores, said plungers being slidable in said main passage of said die with their ends respectively engaging the ends of said blank and engaging and confining all the filler material within said blank throughout the working thereof, a pin extending through said filler material and into both said bores and closing the open ends of said bores adjacent the filler material and being slidably movable in said bores with a close sliding fit preventing the outflow of filler material through said bores when said filler material is squeezed between the ends of said plungers, said pin moving in said bores as the ends of said plungers advance toward each other during the working of the piece, means for forcibly moving said plungers toward each other to work the piece and compress said filler material and cause the lateral leg of said fitting to flow into the said branch portion of the die, the volume of said pin entering said bores during the working of the piece being substantially equal to the diminution of the internal volume of the wrought piece in respect to the original blank.

3. Apparatus according to claim 2 in which said bores and said pin are eccentrically disposed in said plungers adjacent the wall of said blank opposite and remote from the extruded leg.

4. Apparatus according to claim 1 in which said bore and said pin are eccentrically disposed in said plunger adjacent the wall of said blank opposite and remote from the extruded leg.

5. Apparatus according to claim 1 in which said pin is secured to the said other of said plungers.

PAUL D. WURZBURGER.

REFERENCES CITED The following references are of record in the.

file of this patent: v

UNITED STATES PATENTS Number Name Date 1,774,614 Rode Sept. 2, 1930 1,844,250 Hawkins Feb. 9, 1932 2,027,285 Parker Jan. 7, 1936 2,111,695 Seeber Mar. 22, 1938 2,129,120 Davis Sept. 6, 1938 2,138,199 Wendel Nov. 29, 1938 2,203,868 Gray June 11, 1940 2,206,741 Cornell July 2, 1940 2,243,809 Wendel May 27, 1941 2,331,430 Shoemaker Oct. 12, 1943 2,375,599 Walton May 8, 1945 FOREIGN PATENTS Number Country Date 9,889 Great Britain 1900

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