US2740455A - Apparatus for making short radius elbows - Google Patents

Description

w. L. VEATCH 2,740,455

APPARATUS FOR MAKING SHORT RADIUS ELBOWS 2 SheetsSheet 1 April 3, 1956 Filed Dec. 8, 1952 FlG.l. 1::

INVENTOR.

WALTER L. VEATCH BY ATTORNEYS 2 Sheets-Sheet 2 W. L. VEATC H APPARATUS FOR MAKING SHORT RADIUS ELBOWS pril 3, 1956 Filed Dec. 8, 1952 '0 INVENTOR.

WALTER LIB/HATCH BY W 6M ATTORNEYS United States APPARATUS FOR MAKING SHORT RADIUS ELBOWS Walter L. Veatch, Elkhart, Ind., assignor to Northern Indiana Brass Co., Elkhart, Ind., a corporation of lndiana Application December 8, 1952, Serial No. 324,749

8 Claims. (Cl. 15348) The present invention relates to a method and apparatus for making short radius elbows from tubular stock.

It is an object of the present invention to provide a method and apparatus for forming tubular stock into elbows having short radii and characterized by a minimum change in wall thickness of the elbow as compared with the wall thickness of the tubular stock.

More particularly, it is an object of the present invention to provide apparatus for producing elbows from tubular stock which comprises a die having a passage extending therethrough corresponding to the shape of the elbow to be produced, in conjunction with a headed mandrel, the head having cylindrically shaped portions, means for disposing the head of the mandrel at the bend of the passage in the die, means for pressing tubular stock partly around the bend in the die and partly past the head of the mandrel, and means for thereafter withdrawing the head of the mandrel from the die to shape the leg of the elbow which has been pressed past the bend of the die.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, wherein:

Figure 1 is an elevational view of the apparatus for producing elbows.

Figure 2 is a sectional view on the line 2-2, Figure 1.

Figure 3 is an elevational view of a tubular element to be shaped to elbow form.

Figure 4 is an elevational view of the tubular element after it has been shaped to tubular form.

The apparatus comprises a bed of a hydraulic press carrying a vise base 12 on which is located die structure 14. The die structure 14 is composed of two separable parts 14a and 14b, each of which is provided with a recess 16 including a vertically extending cylindrical portion 18, a horizontally extending cylindrical portion 20, and an arcuate portion 22 intermediate and connecting the straight portions 18 and 20. As will be readily understood, the two halves of the die are assembled together with the recesses 16 in registration so as to produce an opening through the assembled die which is of uniform circular cross-section and which has open ends at the top and side of the die assembly as illustrated.

Associated with the die structure 14 is a punch or plunger indicated generally at 24 which includes a cylindrical portion 26 shaped to fit closely within the cylindrical portion 18 of the die passage. At its lower end the plunger 24 is reduced as indicated at 28 and is providedwith a circular shoulder 30 perpendicular to 2,740,455 Eatented 4 Apr. 3, 1956 the length of the plunger 24. The lower end of the plunger is provided with a projecting portion 32 and is spherically concave as indicated at 34 for a purpose presently to be described.

Associated with the die 14 and plunger 24 is a mandrel 36 having a spherically shaped head 38 and a reduced neck portion 49. In the illustrated simplified embodiment of the invention the mandrel is supported in the full line position by a pin 42 extending through a transverse opening in the mandrel and into openings in side plates 44, the plates being interconnected by a top plate 46. Spanning the side plates 44 and slidable vertically thereon is a transverse plate 48 having an opening 50 therethrough for receiving the threaded end 52 of the mandrel 36. The die supporting structure also includes a plate 54 connected to the lower end of the side plates 44 and bolted to the bed 10 by bolts 56. A yoke member 57 is provided having ears S8 bolted to the vise base 12 by the bolts 60 and which engage the sides of the plates 44, thereby completing the assembly of the mandrel supporting structure on the bed 10 of the hydraulic press. Pin 61 spans plates 44 and supports the mandrel 36 when pin 42 is Withdrawn.

Connected by the threaded portion 52 of the mandrel is a nut 62 having spherical surfaces 64 seated in correspondingly shaped spherical surfaces formed at the outer end of the opening 50. It will be observed from the foregoing that the mandrel 36 is mounted for rocking movement about the axis of the pin 42, when the pin is inserted to retain the mandrel in the full line position illustrated. To provide for adjustment of the exact location of the headed end 38 of the mandrel, an abutment screw 66 is provided which extends through a threaded opening in the plate 46. By suitable adjustment of the abutment screw 66, the head 38 may be located with desired clearance with reference to the inner surfaces of the die passage. In actual practice the sphericalportion of the ball head 38 of the mandrel is dimensioned with reference to the circular cross-sectional dimensions of the passage through the die so as to provide an annular space surrounding the ball head at the curved portionof the die passage, this space having a transverse dimension equal to the nominal wall thickness of the tubular blank plus the required clearance factor which in the case of thin walled tube may be about .002".004".

The surface of the mandrel at the zone S which interconnects the neck 40 and the ball head 38, is concavely curved, as best illustrated in Figure 2, to serve as a guiding surface for the portion of the tube located at the inner side of the elbow.

In operation the tubular blank is illustrated at 70 and has bevelled ends 72 and 74 dimensioned to provide the necessary stock to-preserve substantially the same wall thickness in the completed elbow as in the completed stock. The long side 76 of the stock of course corresponds to the outside radius of the elbow and provides the necessary excess stock to prevent excessive thinning of the wall section of the elbow.

The spherical concave end surface 34 of the plunger is shaped to receive and partly envelop the ball head 38 of the mandrel, and the projecting portion 32 of the plunger is to extend the annular space 78 intermediate the reduced portion 28 of the plunger and the adjacent surface of the die passage into proximity to the zone indic'ated-by.theJetteLDcso-asrtonprovidet armaximum guiding action for the material of the tube as it is pressed around the curved intermediate section of the die passage. In practice, the projecting portion 32 of the plunger may be extended into close proximity to the zone indicated by the letter D.

In operation the mandrel 36 is located in the full line position and is retained in such position by the pin 42 which is inserted to extend through aligned openings in the mandrel and the side plates 44. The exact location of the ball head 38 of the mandrel is determined by adiustment' of the abutment screw:.66. As previously indicated the bed 10 is the bed of ahydraulic press and the plunger or pun'ch24 is associated with the" hydraulically actuated movable press head so as topress'the tubular element 70frorn the positionindicate'd in dotted linesin Figure 2 to the tull line position illustrated therein. It willbe observed that'movement-of the plunger 24 forces one endportion ofthe-t'ubular element aroundthe curved intermediate portion-of the die-passage and through the annular space defined between-the ball head 38 and-the adjacent surfaces of the diepassage; The portionof the tubular blank Which=is thus forcedthrough the annular passage is somewhat distorted and'will assumea'shape' somewhat as illustrated in Figure 2. To complete-the elbow the pin 42 is removed and the mandrel ismoved to the right by suitablemeans. In the simplified'illustrative form of the invention=disclosed'hereinmovement of the mandrel may 'be accomplishedby rotationofthe nut 62 so as to=move the ball head38routwardly through the-distorted end'of theelbow. Thereafter, the two halves 1411' and 14b of the die structure maybe separated and the completed elbow'removed. At this-time'the-elbow will have the shape as illustrated at 80 in Figure 4 and to complete it-will require only'trimming of the irregular end 82.

It will be'observedthat the-upper portion of the tubular element 70 is confined in thespace between the reduced guide the portion of the-elbow at the inside of its radius to the shape illustrated in Figure 2, and' withdrawabof the head'of the-mandrel further shapes this'surface to the abruptly curved-radius: illustrated in Figures 2 and 4'.

' The operation results in forming the outer radius of the elbow in compression-by forcing the stock" between thedie-recessandhead'BS. This tends to thicken'the wall of the elbow where it would normally become thin. 'At thesame time the small -inside radius is substantially formed intension by*withdrawalof the mandrel.

. It will be appreciated that:the illustration of the present invention is simplified for clarity. and that in actual 'operation automatic means-may be provided for locating and moving the mandrel in order to speed up'production. However, the'operating principles are illustrated by. the simplified structure disclosed herein and the changes necessary to make the operation morefully automatic .are within-the scope of the present invention.

While the invention has" been'deseribed in conjunction with forming cylindrical tubing,' it will be apparentthat' it is'applicable-to other tubular stock, such as square, oval, etc.

The drawings andthe foregoing specification constitute adescription of the improved method and apparatus. for making short radius" elbows in such full, clear,v concise and exact terms astoenable any person skilled in the art,

to practice'the' invention, the scope of which is indicated by'the appended claims.

. What L elaimnasmylinvention is:

1. Apparatus for forming elbows from tubular open ended elements comprising a die having an elongated passage extending therethrough, said passage consisting of two angularly related straight end portions and a curved intermediate portion connecting said end portions, a plunger movable into one straight end portion of said passage and having a reduced end portion dimensioned to fit within a tubular element which in turn fits within said passage, the reduced end portion being dimensioned to extend at least partly into the curved intermediate portion of said passage, and having a concavity at its end, said plunger having a shoulder engageable with the end of such tubular element, a mandrel having a partly spherical ,head adapted-tqbe located within the nurved intermediate portion of said-passage and to define there with an annular space, means for forcing said plunger into one end of saidpassage-meansfor -supportinggsaid mandrel for movement -into the other" end' or saidj pa'ssage and for movement laterally thereof toprovidefor movement 'of saidnlieadinto the; Vcurvedintermediate portion of said passage and partly into said concavity, means for holding's'aid head'in said-curved intermediate portion during movement of said plunger into the said' one end of said passage and for withdrawing said mandrel to cause its head -to -smooth* out the-portiorr of saicltnbularelement which wvas forced, around the =curved* inter mediate portion ofi said passage.

2. Apparatus-as defined' -in cl arm-*lfirrg which said-pasof said neck as the'lnstde of the'curve'd portion oii's'aid passageisshaped to providea concave curve of; a radius substantiallyinexcese ofthe inside radiusof the curved portion of said passage. g

5-. Apparatus as definedin claim" lfllt which themeans for supporting said-mandrel comprisesa 'pivot-support therefor, andanadjustableabutment eng ageable with saidmandrel'to provide for adjustmentof said-headtrans verselyof said passage. v

6. Apparatus as' defined in claim5j pivonmeans comprising a: removablepivot "element" engageahle with said mandrel to hold said mandrel in positionduring inward movement'bf said plungery saidpivot element-being removable to -provide on jwithdrawal of" said mandtel from said passage.

'1'. Apparatus as defined in claim 1, in which said has transverse dimensions smallerthan theicorresponding transverse dimensions of said QaSSElgdbYfaWaUlQfl Htslightly in excessof twice the nominalwallfithickrress of the tubular elements tobe shaped.

8. Apparatus for formingielbows from-tubuiarfstock comprising a two-piece diejhaving: ani'elongated'. passage extending therethrough, -saidpassage comprising two angularly related straight end portions and'a" curved intermediateporti'onconnecting said endportions, a plunger movable in a working stroke into'one-straight endipprtion of said passage-and having" a' reduced end dimensioned to fit within a tubular element which in turn 4 fits i within said passage; 21' shoulder'at'thednner end pfthe reduced portion of said plunger, said plunger b'ein'g dimensioned to cause theend of its reduced'end' portion" to, extend partlywithin -the curved intermediate portion Off passage at" the end of itsworking stroke; a mandr'elhaving a partly spherical head; movable through-"the other straight portion of'saidjpassage toa fixed'"position;-partly within the curved. intermediate, portion. of said passage, the end of the rducederid portion said lunger having, a recess adapted to receive a. Portion f, said? he means for supportingsaidhead rigidly in, I e P age ea si i r. m v es aipluasn its working stroke .to force a tubular felement; partly around the intermediate curved portion of said passage- 5 to a position in which said head is partly received in said recess, and means for withdrawing said-mandrel to cause its head to smooth out the portion of said tubular element which was forced around the curved intermediate portion of said passage.

Buescher Dec. 8, 1914 Frandsen Dec. 21, 1915 6 Vassilli Mar. 1, 1921 Taylor Oct. 17, 1933 Miotke Feb. 20, 1934 Cornell Mar. 5, 1935 Kvarnstrom Nov. 30, 1943 FOREIGN PATENTS Austria Dec. 27, 1911 Germany July 14, 1914 Belgium July 31, 1952

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