US2767765A - Method of forming tubular fittings and the like - Google Patents

Description

Oct. 23; 1956 E. M. CARTWRIGHT 2,767,765

METHOD OF FORMING TUBULAR FITTINGS AND THE LIKE FilecTJune 21, 1952 1 3 Sheets-Sheet l EVE/7501': I. 172202 Car-M5922 METHOD OF FORMING TUBULAR FITTINGS AND THE LIKE Filed June 21, 1952 Oct. 23, 1956 E. MJCARTWRIGHT 3 Sheets-Sheer 2 Oct. 23, 1956 E. M. CARTWRIGHT 2,767,765

METHOD OF FORMING TUBULAR FITTINGS AND THE LIKE Filed June 21-, 1952 3 Sheets-Sheet 3 United States Patent Ofifice 2,767,765 Patented Oct. 23, 1956 NIETHOD OF FORMING TUBULAR FITTINGS AND THE LIKE Eugene Minor Cartwright, Woodbury, Conn, assignor to Chase Brass & Copper C0. Incorporated, Waterbury, Conn., a corporation I Application June 21, 1952, Serial No. 294,841

3 Claims; (Cl. 153-48) This invention relates to a method of forming tube fittings.

Tubular fittings of this type, i. e. fittings having a smoothly curved bend or bends intermediate their ends, have heretofore been formed from cylindrical cups or shells of ductile metal by thrusting the cylindrical wall of a shell axially into a peripherally fitting die aperture of the desired shape of the fitting-tobe, while at the same time holding the shell against internal collapse, so that the thrust shell wall is compelled to creep along the wall of the die aperture and assume the exact shape of the latter. Thus, fittings of this type, such as elbows, for instance, have been formed by placing in one of the two transverse branches of a die aperture of elbow shape a shell with its closed end bottommost, filling the shell with a liquid or equivalent filler before or after its placement in the die aperture, and then applying at the open end of the shell 2. power punch which entraps the filler in the shell and exerts sufiicient axial thrust on the cylindrical shell wall to causecreepage of a leading length of the latter into the other branch of the die aperture along the confining wall thereof. In thus forming elbow fittings heretofore, a leading length of the shell creeps more or less unrestrictedly into the transverse branch of the die aperture and the major wall portion of this leading shell length is compelled into further motion or displacement directed toward the larger radius of the curved bend between the two transverse branches of the die apertures for uniform distribution of the shell wall in this bend. This further displacement of the major wall portion of the leading shell length takes place in a curved path which is opposite to that followed by this wall portion at and adjacent to the smaller radius of the curved bend in the die aperture. To compel the greater portion of the shell wall in the bend and continuing transverse branch of the die aperture into flowing, continuously during the forming operation, first in one curved direction and then in an opposite curved direction requires in any event a very considerable end thrust on the shell which may readily form wrinkles in the shell wall or even cause collapse of the same if the metal of the shell is not very ductile. Further, the unavoidable displacement of a substantial part of the shell wall in the bend and continuing transverse branch of the die aperture in oppositely curved directions subjects this wall material to very considerable bending stresses which will undoubtedly weaken the shell wall, and may even rupture the same. Accordingly, while this previous method is applicable for the formation of fittings which are of rather ductile metal, it has its practical limitations insofar as the successful formation of many fittings of hard-to-work metal is concerned.

It is an object of the present invention to devise a method of forming tubular fittings of this type from shells the walls of which are, in the course of the forming operation, bent not only much less than in the previous method, but also in one direction only, so that the shell walls are subjected to little stress, and are accurately displaced into their new form on application of an end thrust which in any event is smaller than that required in the previous method.

It is a further object of the present invention to devise a method of forming elbow fittings of this type according to which a shell with a liquid or equivalent filler is placed in a die aperture of the shape of one branch and the bend only of an elbow, whereupon an end thrust is applied to the open end of the shell in order to displace the inner closed end thereof into uniform engagement with the entire wall of the bend, so that on subsequent application of an end thrust on the open end of the shell in a complete elbow die aperture progressive cylindrical wall portions of the shell will easily and harmlessly bend when creeping through the bend in the die aperture, and will no longer be bent when creeping into the end or transverse branch of the complete elbow die aperture.

Another object of the present invention is to devise a method of forming elbow fittings of this type according to which a shell with a liquid or equivalent filler is placed in one branch of a complete elbow die aperture of which the other transverse branch is blocked off to the curved bend in the aperture for and during the initial displacement of the inner closed end of the shell into uniform en gagement with the wall of the bend, whereupon the other branch of the die aperture is cleared for the displacement thereinto of the leading end of the shell on continued application of an end thrust on the open end of the shell.

It is a further object of the present invention to devise a method of forming elbow fittings of this type according to which the transverse branch of a complete elbow die aperture is, yieldingly blocked oif with such a force that the inner closed end of the shell in the other branch of the die aperture is, on application of an end thrust on the open end of the shell, compelled to deform initially into uniform engagement with the entire wall of the curved bend in the die aperture before the leading end of the shell will force its Way into the yieldingly blocked transverse branch of the die aperture,-thus providing assuredly for the described complete initial deformation of the shell, followed without interruption by the finish-formation of the same, all during the application of a continuous end thrust on the open end of the shell.

' Other objects and advantages will appear to those skilled inthe art from the following, considered in conjunction with the accompanying drawings.

In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:

Fig. 1 is a fragmentary top plan view of apparatus embodying one aspect of the present invention and adapted for the formation of tubular fittings in accordance with a certain method which embodies another aspect of the present invention;

Fig. 2 is an elevational view of the same apparatus, viewed in the direction of the arrow 2 in Fig. 1;

Figs. 3, 4 and 5 show at an enlarged scale certain prominent operating parts of the apparatus in different cooperative positions, respectively, in which a tubular fitting passes through progressive stages, respectively, in its formation;

Fig. 6shows a tubular fitting which is partly formed in accordance with the present method, and viewed in the direction of the arrow 6 in Fig. 4;

Fig. 7 is a section taken on the line 77 of Fig. 6;

Fig. 8 is a perspective view of a substantially finished tubular fitting;

Figs. 9, l0 and 11 show certain prominent operating parts of a modified apparatus in difierent cooperative positions, respectively, in which a somewhat differently shaped tubular fitting passes through progressive stages, respectively, in its formation;

Fig. 12 is a section through the differently shaped tubular fitting, substantially as taken on the line -12-12 of Fig. 11;

Fig. 13 is a perspective view of the difierently shaped tubular fitting in a substantially finished state; and

Fig. 14 is a view of a modified die section of the apparatus.

Referring to the drawings, and more especially to Figs. 1 and 2 thereof, the reference numeral designates apparatus for forming seamless tube fittings, and more particularly elbow fittings. These fittings are formed in a die 12 which forms a prominent part of the apparatus and is partible, having complementary'die sections 12a and 1212 which together define a die aperture 14 of the contour and cross-sectional dimensions of the elbow fittings to be formed. The apparatus 10 further comprises a base 16 on which is suitably mounted a block 18 which has a machined recess '20 for the reception of the parted die 12 and operating mechanism 22 therefor. The die-operating mechanism 22 comprises a slide 24 which is held by gibs 26 in a guideway 28 provided in the recess in the block 18. Pivotally connected with the slide 24 by a bolt 30 is one end of a toggle arm 34, the other endof which is pivotally con nected by a bolt 36 with a lever 38. The lever 38 is provided with a relatively long handle arm 40 and a shorter toggle arm 42 which is pivotally connected by a bolt 44 with an anchor block 46.. The anchor block 46 is adjustably mounted in another machined recess 48 in the block 18 by bolts 50 which extend through elongated slots 52, respectively, in the anchor block.

The stationary die section 120 is mounted in any suitable manner in the machined recess 20 in the block 18, bearing against the bottom wall 53 and side wall 54 of this recess in the manner shown in Figs. land 2. The movable die section 121) is in any suitable manner secured to the slide 24 and is movable therewith into and from closing relation with the stationary die section 12a. The die 12 is closed when the lever 38 is turned into the position shown in Fig. 1 in which the toggle arm 42 thereof and the other toggle arm 34 are in substantial alignment and hold the movable die section 12b firmly against the stationary die section 12a, so that the die will safely withstand the very considerable forceswhich in the formation of a tube fitting therein tend to open or part the die sections. The die 12 is opened by retracting the movable die section 12b from the stationary die section 12a on rocking the lever 38, counterclockwise from the lock. position shown in Fig. 1, sufficiently to permit removal of a formed tube fitting from the separated die sections 12a and 121;. By providing for the adjustment of the anchor block 46 as described,

the; action of the toggle arms 34 and 42' may readily be adjusted for maximum lock'eifecton the slide 24 when the lever 38 is in its lock position (Fig. 1). In order to lock the anchor block 46 in its correctly adjusted position, the same bears against adjustable stop screws which are threadedly received in the block 18 and locked in adjusted position by nuts 62.

For the formation of an elbow fitting in the die 12 ina manner described hereinafter, there is also required a yielding plunger 64 which projects into the die aperture 14. The plunger 64 is in this instance carried at 66. by the rod68 of a piston 69 in a cylinder 70 which is bolted orotherwise secured at 72 to the base 16 of the apparatus. For the hereinafter described formation of an elbow fitting in the die 12, there is further required a punch 74 which may be carried at 76 by a plate 78 on the power ram 80 of a hydraulic press or the like.

Reference is now had to Figs. 3 to 5, inclusive, which show. the stationary die section 12a as though viewed in the direction of the arrow 82in Fig. 2-. The companion die section 12b is identical with the die section 12a, except that the die aperture therein is arranged to complement that in the die section 120 to form the die aperture 14 in the closed condition of the die 12 (Figs. 1 and 2). Let it be assumed for the following description of the formation of an elbow fitting in the die 12, that the movable die section 12b is closed against the stationary die section 12a in Figs. 3 to 5. These die sections are closed by turning the lever 38 into the lock position shown in Fig. l, as described. Further, for the formation of an elbow fitting in the die 12, the plunger 64 assumes the end position shown in Figs. 3 and 4 in which the same blocks off the entire transverse branch 14c of the die aperture 14 which, besides the branch 14c, has another branch 14a and a curved bend 14b that connects the branches 14a and 14c. The branches 14a, 14c and the curved bend 14b of the die aperture 14 correspond in contour and cross-sectional dimension to the transverse branches and curved connecting bend of an elbow fitting to be formed in the die. As will be observed in Fig. 3, the smallest curvature c of the bend 14b of the die aperture 14 is of a relatively small radius. The plunger 64 is normally held in the block position shown in Figs. 3 and 4 on admission of compressed air into one side of the cylinder 70 so that the piston 69 therein will assume the end position shown in Fig. l. The piston 69 may be of the double-acting type, so that the plunger 64 may be retracted from the die aperture 14 on admitting compressed air into the other side of the cylinder 70. This may readily be accomplished by connecting the opposite sides of the cylinder with a conventional valve (not shown) which in different positions admits compressed air into'the opposite sides, respectively, of the cylinder and simultaneously vents the other sides thereof.

Elbow fittings of the instant type are formed from shells of ductile metal, such as copper, for instance. One of these shells, designated by the reference numeral 90, isshown in Fig. 3. This shell may conveniently be formed from a flat blank of sheet stock which is drawn, preferably in progressive stages, into the illustrated shell. The shell is, in the present instance, cylindrical and has aclosed bottom 92 which is preferably semi-spherical.

Following is a description of an elbow-forming cycle of the apparatus. Assuming that the die 12 is closed, the plunger 64 is in its normal block position (Fig. 3) and the punch 74 is retracted as shown in Fig. 2, a shell 90 is inserted endwise into the vertical branch 14a of the die aperture 14 until its curved bottom 92 rests against the curved bend 14b in the die aperture in the fashion shown in Fig. 3. A non-compressible filler 94 is placed in the shell. 90 prior to or after its insertion in the die aperture 14. The filler 94 is in this instance a liquid, such as water, for instance. Next, the power ram 80 is permitted to descend. During the descent of the power narn80 from-.itsretracted position (Fig. 2) a diametrically reduced pilot end 98 of the punch 74 will first enter the open end 100 of the inserted shell 90 until an annular shoulder 102 on the punch moves into seating engagement with the adjacent end 104 of the cylindrical shell wall. The pilot end 98 of the punch 74 has a fairly accurate fit in the shell 90 and the liquid displaced by this pilot. end escapes from the shell' through a duct 106 in the punch 74. The duct 106 is closed by the cylindrical shell wall just before the annular shoulder 102 on the punch 74 moves into seating engagement with the adjacent end 104 of the shell wall, so that the liquid then fills the entire remaining volume of the shell and is socurely. trapped therein.

On continued descent of the punch 74 after engagement of its annular shoulder 102 with the adjacent end 104- of theshell Wall, the shell 90'will be axially forced deeperinto the die aperture 14. This forced inward mo tionofthe. shell 90 will tend to displace the curved bottom 92 of the shell against the wall of the curved bend 14b of the die aperture 14, as well as against the end face 110 of the plunger 64 which forms a Wall means terminating the bend portion 1411. However, the air in the cylinder 70 is so highly compressed that the plunger 64 will not yield from its block position and elfectively prevents motion of any of the shell material along the branch portion 140 of the die recess until the shell wall is displaced into complete fitting engagement with the wall of the entire bend 14b of the die aperture 14 (Fig. 4). In thus becoming displaced against the wall of the entire bend 14b of the die aperture, the shell wall will follow the path 'of least resistance in filling out the space in the bend 14b, the shell wall being prevented from following any other course due to the then non-yielding state of the plunger 64 and the entrapped non-compressible filler 94 in the shell which securely holds the latter against internal collapse. Thus, it is at this intermediate stage in the formation of an elbow fitting that wall material of the shell has already been flowed or displaced from the smaller radius curvature of the bend 14b toward the larger radius curvature thereof in the exact amount required to compensate for the deficiency of wall material at the larger radius curvature of the bend 14b, and no further compensating flow of wall material of the shell toward the larger radius curvature of the bend 14b is required in the further formation of the elbow fitting.

Accordingly, it is only after the shell wall has definitely been displaced into fitting engagement with the wall of the entire bend 14b of the die aperture (Fig. 4), that the plunger 64 offers the least resistance to further displacement of the non-collapsible shell wall during continued descent of the punch 74. Hence, on continued descent of the punch 74, the leading end of the shell 90 will creep into the branch 140 of the die aperture, with the shell wall being securely held in uniform engagement with the wall of the die aperture and with the inner end face 110 of the then yielding plunger 64 by the entrapped non-compressible filler 94 in the shell. By virtue of the earlier displacement of the wall of the shell against the Wall of the entire curved bend 14b of the die aperture (Fig. 4), the displacement of successive lengths of the cylindrical portion of the shell into the bend 14b of the die aperture will bring about the displacement of equal successive shell lengths into the straight branch 140 of the die aperture, and the shell wall is subjected only to simple bending around the bend 14b of the die aperture and subsequent unbending when the shell is displaced into the transverse branch 140 of the die aperture. The bending stresses to which the shell wall is subjected in the course of its formation into an elbow fitting are, therefore, by no means excessive and do not appreciably Weaken the shell wall.

Fig. 5 shows the full extent of the displacement of the shell 90 in the branch 140 of the die aperture with the punch 74 at the end of its work stroke, and the formation of the fitting in the die 12 is now completed. To effect retraction of the plunger 64 from the finished fitting in the die prior to, and in any event not after, the start of the punch 74 into its retracted position, an adjustable set screw 120 on the power ram 80 engages and operates a limit switch 122 (Fig. 2) which in any suitable manner may control the before-mentioned valve for causing retraction of the plunger 64. Since the control of the operation of the plunger 64 and power ram 80 does not form any part of the present invention, no further disclosure thereof is deemed necessary. The operator may, after the return of the punch 74 into its retracted position, swing the lever 33 from its lock position to cause separation of the die sections 12a and 12b and permit the safe removal of the formed elbow fitting. After the elbow fitting is thus removed from the die, the beforementioned valve may be operated for the return of the plunger 64 into the end position in Figs. 3 and 4 for the following formation of another elbow fitting.

The elbow fitting, finished insofar as its formation in the die 12 is concerned, is shown in section in Fig. 5 and designated by the reference numeral 124. This fitting 124 is, of course, not a finished elbow fitting since its internal passage is closed by the end wall 126. The end wall 126 of the fitting may subsequently be removed by cutting, leaving the elbow fitting 124' in the condition shown in Fig. 8 for use as such or for a further machining operation or operations, such as threading, for instance.

Although the described formation of the elbow fitting from the shell 90 is uninterrupted at any stage, the formation of the shell into the intermediate fitting blank 108 (Figs. 4, 6 and 7) constitutes a significant stage in the overall formation of the fitting. Thus, the formation of the shell 90 into a fitting may be stopped when the same reaches the stage of the fitting blank 108 with its complete bend 109, and this fitting blank 108 may be used as such, i. e. without an extended transverse branch, for certain purposes. Accordingly, the descent of the power ram may be stopped when the shell is deformed into the fitting blank 108 (Fig. 4), and the latter may be removed from the die. Further, the elbow fitting 124 maybe formed progressively in two dies, if de-,

sired for any purpose. Thus, a shell 90 may first be formed into a fitting blank 108 in a die (Fig. 14) the companion die sections of which have a die aperture 132 which conforms to the shape of the fitting blank 108, i. e. is devoid of the other transverse branch of a full elbow fitting. The fitting blank 103 thus formed in the die 130 may either be used in this form as an elbow fitting, or may be formed further into an elbow fitting 124 with its extended transverse branches. If formed further into an elbow fitting 124, the fitting blank 108 may be placed into a die similar to the die 12 (Fig. 4), and further deformed therein into the complete fitting 124 in the presence or absence of the plunger 64, though preferably with the plunger 64 yieldingly resisting the advance of the fitting blank 108 into the transverse branch 14c of the die aperture 14. In this case, however, the plunger 64 need not resist the advance of the fitting blank 108 to the same extent as in the previously described fitting formation in which the plunger is called upon to resist any advance of the shell 90 into the branch of the die aperture 14 until the shell wall has been displaced into fitting engagement with the wall of the entire bend 14b of the die aperture.

Figs. 9 to 11 show the formation of a different elbow fitting 140 in a die 142 of which one of the partible sections is shown. The instant elbow fitting 140 distinguishes from the previously described fitting 124 in that one of the transverse branches 144 of the fitting 140 is diametrically smaller than the other branch 145 thereof, and the branches of dilferent diameters are smoothly joined by the bend 146 of the fitting (see also Fig. 12). Fig. 9 shows a shell 90, with a non-compressible filler 94 inserted in the die 142. Next, a power punch 74' is lowered to form the shell 90 into the fitting blank 108 (Fig. 10). As in the previous example, the plunger 64' resists the advance of the shell 90 into the branch 140' of the die aperture 14 until the shell wall has been displaced into fitting engagement with the wall of the entire bend 14b of the die aperture. Thereafter and on continued descent of the power punch 74', the plunger 64 will yield and a leading length of the shell will be displaced into the branch 140 of the die aperture (Fig. 11). After removal of the elbow fitting 140 from the die 142, the closed end 150 of the fitting may be cut away to form the fitting 140' (Fig. 13).

The instant method of forming elbow fittings is highly advantageous in several respects. Thus, by virtue of the formation of a shell first into a fitting blank of the shape on one branch and the bend only of the complete elbow fitting, and then into the finished fitting, bending of the shell material and stresses therein are kept at a minimum, with the result that the wall of the fitting is not appreciably weakened and a relatively small force is required for the displacement of the shell in the die aperture. The formation of the elbow fitting in the two distinct stages described also permits the use of the intermediate fitting blank as an elbow fitting having one branch and the complete bend of an elbow. Moreover, by virtue of the yieldability of the blocking plunger in the die aperture and its resistance to displacement of a shell into the transverse branch of the die aperture until the shell wall has been displaced into fitting engagement with the wall of the entire bend of the die aperture, shells may be formed into accurate elbow fittings despite even wide tolerances in their longitudinal and crosseectional dimensions, or despite some wear of the sections of the die in which they are formed.

While the foregoing description of the invention has dealt with seamless shells for their formation into elbow fittings, it is to be understood that the present invention applies equally well to shells having a seam or seams, such as a brazed joint or joints, for instance.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

What is claimed is:

1. In a method of forming from a straight tubular shell with a closed, rounded end, a tubular fitting having angularly related branches and a curved connecting bend, the steps of placing the shell, closed end foremost, into one branch portion of a partible die aperture having branch portions and a bend portion of the shape and cross-sectional size of the branches and connecting bend of the desired fitting; axially forcing the shell, while holding it against internal collapse, into the die aperture and initially blocking the other branch portion of the die immediately at its juncture with the bend portion by a plunger arranged to yield under a predetermined force and having a substantially fiat end normal to the axis of said other branch which prevents movement of said tube into said other branch until one side of said rounded end of said tube is substantially flattened against the end of said plunger; and subsequently forcing the shell further into the die aperture around said bend portion and into said other branch portion against the yieldable opposition of said plunger, while holding the shell against internal collapse.

2. In a method of forming from a straight tubular shell with a closed, rounded end, a tubular fitting having angularly related branches and a curved connecting bend, the steps of placing the shell, closed end foremost, into one branch portion of a partible die aperture having branch portions and a bend portion of the shape and crosssectional size of the branches and the connecting bend of the desired fitting; yieldingly blocking the other branch portion of the die immediately at its juncture with the bend portion by a substantially fiat-ended plunger having an end face normal to the axis of said other branch portion, said plunger being urged thereinto with a predetermined force; axially forcing the shell into the die aperture while simultaneously holding the shell against internal collapse until said rounded end is displaced toward said plunger by the bend portion of the die aperture and into contact with the end of the plunger, setting the predetermined force on the plunger at a value such that it will stay in blocking position until the one side of said rounded end is substantially flattened against the end of said plunger, and thereafter forcing the shell further into the die aperture through said bend portion and into said other branch portion against the opposition of said plunger, while holding the shell against internal collapse.

3. In a method of forming from a straight tubular shell with a closed, rounded end, a tubular fitting having angularly related branches of different diameters and a curved connecting bend, the steps of placing the shell, closed end foremost, into the branch portion of larger diameter of a partible die aperture having branch portions and a bend portion of the shape and cross-sectional size of the branches and the connecting bend of the desired fitting; axially forcing the shell, while holding it against internal collapse, into the die aperture and initially blocking the branch portion of smaller diameter immediately at its juncture with the bend portion by a plunger arranged to yield under a predetermined force and having a substantially fiat end normal to the axis of said branch of smaller diameter, which plunger is efiective to prevent movement of said tube into said smaller branch until one side of said rounded end is substantially flattened against the end of said plunger; and subsequently forcing the shell further into the die aperture around said bend portion and into said smaller branch portion against the yieldable opposition of said plunger, while holding the shell against internal collapse.

References Cited in the file of this patent UNITED STATES PATENTS 1,947,611 Mioke Feb. 20, 1934 2,138,199 Wendel Nov. 29, 1938 2,188,197 Wendel Ian. 23, 1940 FOREIGN PATENTS 463,651 Great Britain Apr. 5, 1937

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