CZ20031109A3 - Process and apparatus for hydroforming a tubular component - Google Patents

Abstract

A method and apparatus for shaping a raw tube into a formed part. The part can be configured within a die assembly including a hydroforming die structure and a pair of tube-engaging punches. The punches are inserted into the ends of the raw tube to shape the ends into the desired configuration. The middle portion of the raw tube is shaped into the desired configuration by hydroforming. Thus, the method and apparatus can shape the raw tube along its entire length, leaving no remnants of the raw tube that must be trimmed away.

Description

Technical field

The invention generally relates to an improved apparatus and method for more efficient hydroforming of a tubular member. More specifically, the invention relates to apparatus and methods that utilize a punch to mold both ends of a component into the desired configuration and hold the component during hydroforming.

BACKGROUND OF THE INVENTION

Typically, the raw tube for forming the tubular member by hydroforming is placed in the hydroforming means and closed at its ends. The middle portion of the raw tube is then subjected to hydroforming leaving a transition region between the ends of the raw tube and the hydroformed middle portion. The hydroformed component is then completed by removing both transition regions from the tube leaving only the fully molded central portion. The ends of the tube may be secured by end portions having a wedge shape as described in EP 1022073A1. Hydroforming is also described in U.S. Patent Nos. 5,987,950 to Horton and 6,014,950 to Jaekel et al.

Removing the ends of the hydroformed part is a source of inefficiency. For example, the cut ends become waste material. End cutting requires additional cutting tools, which complicates the equipment needed to create a finished part. Furthermore, time is wasted by performing an additional step of trimming the transition regions at each end.

REPLACEMENT SHEET

16041

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SUMMARY OF THE INVENTION

One object of the invention is to provide an improved apparatus and method for forming a hollow part.

Another object of the invention is to provide an improved device and method for efficiently and cost-effectively molding a hollow part by mechanically shaping at least one end of the part and hydroforming a portion thereof.

Yet another object of the invention is to provide an apparatus and method for forming a part that uses a punch to close each end of the part, wherein the punch shapes the end such that each end has the same configuration as the hydroformed central portion.

The foregoing objectives are substantially achieved by providing a mold assembly for hydroforming a workpiece from a tubular blank, wherein the workpiece has a desired configuration different from that of the blank and includes a desired cross section at one end thereof, the mold assembly comprising: a mold structure with internal surfaces bounding the mold cavity having a cross-sectional arrangement corresponding to the desired cross-section of the member and a pair of tube end connection structures located at opposite ends of the mold cavity and designed and arranged to engage opposite ends of the tube blank, the tube end structures being designed and arranged to seal opposite ends of the tube blank; for compressing the hydroforming fluid in the tubular blank to expand it to conform to the inner surfaces of the mold cavity, the first of the structures for bonding the end of the tube arrangement of an outer cross section corresponding to the desired cross section at one end part and is movable into forced engagement with one end of the tubular blank to one end of the adjustment • · · ·

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Of a cross-section of the first and therefore predetermined tubular blank of the outer structure of the structure for connection to the ends of the tube, of a determined cross section at one end of the tubular tubular component of the structures

The foregoing objectives are also achieved by providing a method of forming a hydroformed component comprising the steps of:

providing a hydroforming assembly of a tubular blank having a desired configuration different from that of the blank and having a desired cross-section at one end of the component, the mold assembly comprising a mold structure with internal surfaces defining a mold cavity having a cross-sectional arrangement corresponding to the desired cross-section and a pair of pipe end structures located at opposite ends of the mold cavity and designed and arranged to mate with opposite ends of the tubular blank, the tubular end structures being designed and arranged to seal opposite ends of the tubular blank and to compress the fluid for hydroforming in the tubular blank. a tubular blank for expanding it to conform to the inner surfaces of the mold cavity, the first of the structures for engaging the ends of the tubing has an outer cross-section corresponding to the desired cross-section at one end of the workpiece and movable into forced engagement with one end of the workpiece to accommodate the workpiece exterior to engage the pipe ends with one end of the first and therefore predetermined cross section at one end of the workpiece; a tubular blank for forming the tubular blank into a desired component configuration.

Other objects, advantages and important features of the invention will become more apparent from the following detailed description, the accompanying drawings, and the claims.

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BRIEF DESCRIPTION OF THE DRAWINGS

Giant. 1 is an exploded perspective view showing upper and lower structures and box-shaped punches of a hydroforming mold assembly according to the principles of the present invention;

Fig. 2 is a longitudinal sectional view of the mold assembly for hydroforming along section line 1-1 of Fig. 1 and including a tubular blank positioned within the lower mold structure, the upper mold structure being shown in a raised or fully open position, and the box punches engaging the ends of the tubular blank;

Fig. 3 is a longitudinal sectional view of the hydroforming mold assembly similar to Fig. 3 but showing the upper mold structure in the fully lowered position, with the tubular blank positioned in the lower mold construction and box-shaped punches inserted into the ends of the tubular blank and fluid injected into the tubular blank;

Fig. 4 is a cross-sectional view taken along section line 4-4 of Fig. 3 and showing an unstretched oval tubular blank disposed in a hydroforming assembly and filled with hydroforming fluid;

Fig. 5 is a cross-sectional view taken along line 5-5 of Fig. 9 showing a tubular blank expanded by fluid under pressure in the expansion region of the co-operating upper and lower hydroforming molds;

Fig. 6 is a partial perspective view of a box-shaped punch engaging a tubular blank in partial cross-section;

Fig. 7 is a longitudinal section taken along line 7-7 of Fig. 6 showing a box-shaped punch;

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16041 -5 "Fig. 8 is a cross-sectional view taken along section line 8-8 of Fig. 9 showing the end of the tubular blank between the upper and lower clamping structures with an inserted box-shaped punch;

Fig. 9 is a longitudinal sectional view showing a hydroforming step in which the upper mold structure is in the fully lowered position and the tubular blank has been hydraulically deformed into an expanded configuration by fluid under pressure;

Fig. 10 is a longitudinal sectional view showing the use of hydraulic forming piston extensions attached to the punches to allow hydroforming of a relatively short blank in a relatively long hydroforming mold assembly; and Fig. 11 is a longitudinal sectional view of a hydroforming mold assembly with box-shaped punches and round punches semi-finished product.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is an exploded perspective view of a hydroforming mold assembly generally designated 10 in accordance with the present invention. The hydroforming mold assembly 10 includes a movable upper mold structure 12, a movable lower mold structure 14, a rigid mold structure, and a rigid base 18 to which the rigid mold structure 16 is secured. A plurality of pneumatic or nitrogen spring rollers 20 fasten the lower mold structure 14 movably to a rigid base 18. The upper mold structure 12, the lower mold structure 14 and the rigid mold structure 16 cooperate to define a longitudinal mold cavity therebetween having a substantially box or multilateral cross section as will be described here. The upper mold structure 12, the lower mold structure 14, the rigid mold structure 16, and the rigid base are preferably made of a suitable steel material, such as P-20 and / or steel 2714.

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As shown in Fig. 1, the upper mold structure 12 defines at its opposite longitudinal ends a pair of saddle regions 22. The saddle regions 22 are shaped and arranged to receive and seat upper clamping structures 26 at opposite ends of the upper mold structure 12. Clamping structures 26 are each connected to the upper mold structure 12 in respective seat regions 22 by a plurality of pneumatic or nitrogen spring rollers 24 that allow relative vertical movement between the clamping structures and the upper mold structure 12.

The lower mold structure 14 has similar seat regions 30 at its opposite longitudinal ends which are shaped and arranged to seat the lower clamping structures 28 in a similar manner. As shown, the longitudinal ends designated 15, forming the saddle region 30 of the lower mold structure 14, generally have a U-shaped configuration.

The lower clamping structures 28 each have upwardly facing surfaces 34 with a cross-sectional configuration that defines one half of the polygonal surface arrangement. In the context of the present invention, the term multilateral means square, rectangular, parallelogram, polygonal or any other non-circular and non-oval arrangement. In the illustrated embodiment, the surface 34 defines a half of the rectangle.

In the illustrated embodiment, the two upper clamping structures 26 are substantially identical to, but inverted relative to, the lower clamping structures 28. More specifically, each upper clamping structure 26 has a downwardly facing surface 36 with a cross-sectional configuration that defines the second half of the polygonal (i.e., rectangular) surface arrangement. The surface 36 of each clamping structure 26 interacts with the surface 34 of the corresponding lower clamping structure 28 to form a clamp structure.

16041, a multi-angled clamping surface that grips the end portions of the tubular blank 40 when the upper mold structure 12 is lowered.

As can be seen from, for example, FIGS. 2, 3 and 4, the upper mold structure 12 defines a substantially U-shaped longitudinal channel 38 with a cross-section. The channel 38 is delimited by a downwardly extending, generally horizontal longitudinally extending surface 22 and spaced apart longitudinally extending vertical side surfaces 43 which run parallel to one another from opposite sides of the surface 44.

The lower mold structure 14 has a central opening 42 that extends vertically between the U-shaped longitudinal ends 15. A fixed mold structure 16 extends into the opening 42. The inner vertical surfaces 41 in the lower mold structure 14 define the aforementioned central opening 42. More specifically The side surfaces 41 erase the side edges of the aperture 42. The surfaces are vertically positioned in a mutually parallel position facing each other. The U-shaped end portions 15 of the lower mold structure 14 define the longitudinal edges of the aperture 42, and have inner surfaces (not shown) positioned vertically in a mutually parallel position facing each other.

The rigid base 18 is in the form of a substantially rectangular metal plate. The rigid mold structure 16 is attached to the upper surface 46 of the solid base 18. The rigid mold structure 16 is an elongated structure that extends along a major portion of the length of the upper surface 46 of the solid base 18. The rigid mold structure 16 extends upwardly from the solid base 18 and has substantially vertical side surfaces 48 on opposite longitudinal sides thereof. The rigid mold structure 16 is designed and arranged to protrude into an opening 42 in the lower mold structure 14 with minimal clearance between the generally vertical side surfaces 48 of the solid mold structure and

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Similarly, the minimum clearance between the inner transverse surfaces (not shown) and the end portions 15 of the lower mold structure 14 and the vertical end surfaces 49 of the solid mold structure 16. The solid mold structure 16 further comprises an upside down, generally horizontal and a longitudinally extending mold surface 50 that is constructed and arranged to extend at a distance from the longitudinally downwardly facing mold surface 44 of the upper mold structure 12. As best seen in Figures 4 and 5, the aforementioned side surfaces 41, the upwardly facing surface 50 the side surfaces 43 and the downwardly facing surface 44 cooperate in defining the mold cavity 52 with the polygonal cross-sectional configuration extending substantially over the entire longitudinal extent. The mold cavity surfaces define the desired shape of a component formed from a circular or oval semifinished tube.

Giant. 2 shows the upper mold structure 12 in the open or raised position. In this position, the hydroforming mold assembly 10 allows placement of the tubular blank 40 into the lower mold structure 14.

After the blank 40 is placed in the lower mold structure 14, the upper mold structure 12 is lowered to form the mold cavity 52. The mold cavity may eventually be smaller than that shown in Fig. 4 to slightly press the tubular blank 40 before that. before the blank 40 is stretched in a hydroforming operation, as described in US Patent No. 5,987,950 (Horton), which is incorporated herein by reference. With the tubular blank 40 positioned between the closed upper mold structure 12 and the lower mold structure 14, the hydraulic forming pistons 80 with punches 81 attached to the fastening structures 90 are ejected from opposite sides of the hydroforming mold assembly 10 to engage opposite ends of the tubular blank 40. As shown in FIG. most clearly shown in FIG.

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16041 -96 and 7, each plunger 81 includes an initial tapered portion 82 that merges into a polygonal, here rectangular, portion 84. The base 86 forming the lateral shoulder 88 is formed at one end of the polygonal portion 84 opposite the initial tapered portion 82.

The punch 81 is attached to the end of the mounting structure 90 by means of mechanical fasteners 92 such as screws through cylindrical recessed holes 94 formed in the punch 81 and into the holder 92. The base preferably has a size and shape that is complementary to the size and shape of the mounting structure 90 transition between punch 81 and mounting structure 90.

In the illustrated embodiment, the tapered portion 82 is preferably formed at an angle Θ (see Figure 7) of between about 13-17 ° and most preferably about 15 ° relative to the sides of the box-shaped portion 84. The polygonal portion 84 preferably has straight sides to have a perimeter that defines a polygonal shape such as a polygon, a square rectangle, an oblique parallelogram, and the like. The peripheral shape of the box portion 84 substantially corresponds to the shape of the clamping structure formed by the upwardly facing surface 34 of the lower clamping structure 28 and the downwardly facing surface 36 of the upper clamping structure 26. so as to provide a sealing stationary fit with the wall of the tubular blank 40 with gripping surfaces providing external support for the blank 40.

The front end 83 of the punch 81 at the free end of the tapered portion 82 has dimensions that are smaller than the dimensions of the polygonal portion 84 and thus allows insertion of the front end 83 into the unstretched end of the tubular blank 40 as shown in FIG. engaging the end of the blank 40, the hydraulic forming piston can be further extended by the force of hydraulic pressure, thereby pushing the plunger 81 into the end of the tubular blank 40 after the upper mold structure is.

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3. The tapered portion 82 of the punch 81 gradually forms the end of the blank 40 until the polygonal portion 84 is fully inserted into the end of the blank 40. During this procedure, the end portion of the blank 40 may be stretched outwardly as they conform to the polygonal portions 84 and hence the adjacent clamping surfaces 34, 36, as best shown in FIGS. 3 and 8. The width of the lateral shoulder 88 is preferably substantially equal to the thickness of the tubular blank 40 so that the outer surface of the tubular blank 40 blends smoothly into the outer surfaces of the base 86 of the holder 90.

Thus, when the tube is shaped over the punch to fit with the finished tube shape, it will not be necessary to remove the waste portion of the blank, this eliminates the need for a cutting tool, saving money and time.

While the above description corresponds to only one punch, it should be understood that this description may relate to both punches 81 at opposite ends of tube 40.

The tubular blank 40 may be round (circular cross-section). The punches 81 have similar height and width dimensions as the blank. The blank may be oval for punches that are rectangular or otherwise elongated along the height or width dimension. Hydroforming processes using tubular blanks are described in U.S. Patent No. 5,987,950, the disclosure of which is incorporated herein by reference, as set forth above. Providing a tubular blank with an oval cross-section is advantageous compared to a conventional circular cross-section because it provides a circumference closer to the final cross-sectional circumference of the generally box-shaped (non-square) mold cavity 52. Thus, less expansion of the blank 40 is required In addition, the closer shape of the blank 40 and the surfaces of the cavity allows the blank to expand more easily into the corners of the cavity.

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52, where stretching is most difficult due to increasing frictional surface contact between the outer surface of the blank and the cavity surfaces during expansion of the blank 40.

As can be seen in FIG. 3, the blank 40 is substantially held rigidly in place between the mold structures 12 and 14 and the hydraulic forming cylinders or pistons 80 are telescopically and tightly inserted into the opposite ends of the blank 40 such that the tapered surfaces 82 The pistons 80 are pushed inwards to cause the opposite edges of the workpiece 40 to move downwardly on the surface 82 until it engages the surface 88 and thus does not transform the end portion of the workpiece into the outer shape of the die portion 84. The hydraulic forming rollers then pre-fill but do not pressurize the tubular blank 40 to any greater extent with a hydroforming fluid (preferably water) as indicated by reference numeral F. Hydraulic fluid is injected through a channel 87 formed in punch structures to favor a pre-filling operation to shorten cycle times and achieve a smoothly shaped component By application, the upper mold structure 12 can be fully lowered before any fluid is introduced into the tubular blank 40.

81, which is connected 90. Although it is given in one or both with the corresponding mounting

The end portions of the sealed mold cavity 52 are generally rectangular in shape as defined by the surface portions 54 that are generally the same size and shape as the gripping surfaces 34, 36 of the respective grip structures 28, 26. Thus, the portions 54 define the mold cavity areas having a transverse area. 6. In other words, the portions 54 of the mold cavity 52 define the mold cavity surfaces which, when the punches 81 are pushed into the ends of the tubular portion, as shown in FIG. are used for

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· 9 • 9 9999

Stretching the tubular blank 40 during the hydroforming process only to the extent required to convert the blank shape from a round or oval cross-section to a polygonal (here rectangular) cross-sectional configuration. Since the end portions of the blank 40 flush with the punches 81 (as shown in FIG. 6) will form the shape required for the final hydroformed member and will not form an unstretched portion that must be cut after the hydroforming process so that the remaining uncut parts of the tube correspond to the desired member. substantial waste material is saved. Each non-expanded mold construction surface portion 54 defines a shape consistent with the shape of the die portions 84 and 86.

The cavity 52 may also include an enlarged portion 56 toward its longitudinally central portion. With the upper mold structure 12 closed relative to the lower mold structure 14 and with the punches 81 tightly inserted into the ends of the blank 40, the fluid F may be compressed to expand the tubular blank 40 until it adapts to the surfaces defining the cavity 52 (see Figures 5 and 9). . The tubular blank 40 is expanded to a non-rounded polygonal (e.g., rectangular) shape of the mold cavity 52. If the hydroforming assembly includes a mold cavity with an enlarged portion 56, the blank will be expanded in that region. Since the portions 54 of the mold cavity 52 define shapes that are consistent with the shape of the polygonal portion 84 of the punches 81, the hydroformed portion has a consistent shape to its ends and there is no need to cut its end portions. If a portion of the blank is to be significantly enlarged in its cross-sectional circumference (e.g., greater than 5% relative to the original periphery of the blank), it may be advantageous to squeeze the longitudinal ends of the blank toward each other to add wall thickness as the blank is expanded. If the blank is not to be enlarged but is merely expanded to conform to the shape of the polygonal mold cavity, longitudinal movement of the ends during expansion of the blank may not be necessary. More · * ·· • ·

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9 9

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Details of the preferred hydroforming process are described in U.S. Patent No. 014,879 to Jaekel et al., The disclosure of which is incorporated herein by reference.

According to another embodiment, when a significant expansion of the circumference is required at one end of the tubular member such that substantial wall thickness supplementation is required, it is generally preferred to utilize a circular or oval punch at the opposite end to the polygonal punch. This is because the material flows more efficiently and more regularly into the region of enlargement from the round end than from the box end. Such a hydroforming arrangement is shown in Fig. 11, in which the surrounding mold structures are not shown for clarity of illustration. The illustrated arrangement comprises one hydraulic forming piston 80 with a chamfered rectangular plunger 81 and a rectangular-shaped mounting structure 90 as shown and described previously. The arrangement also includes a second hydraulic forming piston 100 that includes a cylindrical base portion 112 and a smaller cylindrical portion 102 with an insert chamfer 116 formed at the end. A circular, annular sealing shoulder that engages the end of the tubular blank 40 'is defined between the base portion 112 and the cylindrical portion 102.

At the end of the blank 40 with the plunger 81 engaging therein, the mold construction (not shown) represents a surface arrangement that shapes the blank 40 'such that the cross-sectional arrangement in the blank 110 extends only to the extent that the round cross-section of the blank cross-section. The portion 110 is connected successively to a widening section 108 that passes into a portion 106 with an enlarged rectangular cross section. Conversely, at the end of the blank 40 'into which the cylindrical punch 100 engages, the mold construction constitutes a surface configuration that shapes the relatively short, non-enlarged cylindrical portion 105 of the blank. The blank then

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* 14 passes from a circular circumference in section 105 to a rectangular cross section in section 106. The punch 100 allows a relatively large expansion of the enlarged region 106 and a steep transition region 104 because of longitudinal pressing at the end of the tubular member. 40 'is more effective for adding wall thickness when the punch is round. The cylindrical end portion of the molded part formed by the cylindrical punch 100 could normally be cut off during the subsequent finishing operation.

The box-shaped end formed by the rectangular shaped punch 81, on the other hand, can be adapted to the desired final shape of the part so that the end need not be cut off.

As shown in FIG. 10, one or more piston extensions 120 may be installed between the punch 81 and the holder 90. The extensions 120 have a rectangular cross-sectional configuration that is identical in shape to the rectangular cross-sections of the mounting structure 90 and the base 86 of the punch 81. accordingly, the hydraulic forming pistons 80 'may extend further into the relatively non-enlarged portions 54 of the mold cavity 52 to assist in hydroforming the shorter tubular blanks 40' in the same mold cavity 52. Of course, the long blanks 80 'cannot extend into the enlarged region 56 of the hydroforming cavity 52; the seal between the end of the tubular blank 40 'and the shoulder 88 of the punch 80 will be lost as the tubular blank expands into the enlarged region 56.

Thus, the present invention includes a mold assembly for hydroforming a tubular blank component comprising a mold structure with internal surfaces defining a mold cavity with a cross-sectional configuration corresponding to a predetermined cross-section of a predetermined configuration of a different component having a predetermined from the blank and having a predetermined cross-section at its end .

• 4 · 4 · 4 · 4 · 4

It will be appreciated that the foregoing detailed description and accompanying drawings of preferred embodiments are illustrative only, and that the present invention encompasses all other embodiments within the spirit and scope of the disclosed embodiments and the appended claims.

Claims (7)

PATENT CLAIMS A mold assembly (10) for hydroforming a workpiece from a tubular blank (40), the workpiece having a desired configuration different from that of the blank and comprising a desired cross-section at one end thereof comprising a mold construction with internal surfaces defining the mold cavity (52); having a cross-sectional configuration generally corresponding to the desired outer shape of the component, the mold assembly (10) further comprising: a pair of tube end engagement structures (81) disposed at opposite ends of the mold cavity (52) and designed and configured to engage opposite ends of the tubular blank (40), wherein the tube end engagement structures (81) are designed and arranged to seal opposite ends of the tubular blank (40) and for supplying pressurized hydroforming fluid to the tubular blank (40) to expand the tubular blank (40) into a shape coincident with the inner surfaces of the mold cavity (52), the first of the structures (81) for engaging the tubular ends having an external cross-sectional configuration corresponding to the desired cross-sectional at one end of the component and movable to forcefully engage one end of the tubular blank (40) to transform it into the external cross-sectional configuration of the first of the tubular end engaging structures (81) and of the Articles of Association cross section at one end of the part. The mold assembly (10) of claim 1, wherein the first tubular end engagement structure (81) has an outer surface comprising a tapered portion (82) that is partially inserted into one end of the tubular blank (40) and REPLACEMENT SHEET ·· · Μ · ··· ···· · · · · ··················· 16041-17 moves further into the end of the tubular blank (40) to cause the inner surface portions of the end of the tubular blank (40) to slip into a forced position along the tapered portion (82) and deform i) over the first tubular end engagement structure (81); ) to coincide with the outer surface of the first tube end engagement structure (81) and wherein one end of the mold cavity 52 receives the first tube end engagement structure (81), the inner surfaces of the mold cavity (52) at said one end of the mold cavity (52) having an arrangement coincident with that of the outer surface of the component at said one end of the component. A method of manufacturing a hydroformed component using a mold assembly (10) for hydroforming a component from a tubular blank (40) having a desired configuration different from that of the blank and comprising a desired cross section at one end of the component, the mold assembly (10) comprising a mold construction with internal surfaces defining the mold cavity (52), the cross-sectional arrangement of which is coincident with the desired cross-section of the component, the method comprising the steps of: providing a pair of tube end engagement structures (81) disposed at opposite ends of the mold cavity (52) and designed and configured to engage opposite ends of the tubular blank (40), wherein the tube end engagement structures (81) are designed and arranged for sealing the opposite ends of the tubular blank (40) and for supplying pressurized hydroforming fluid to the tubular blank (40) to expand the tubular blank (40) to coincide with the inner surfaces of the mold cavity (52), the first of the tubular engagement structures (81) end has outer REPLACEMENT SHEET 16041 -18 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 • 9 999 9 99 99 99 9 cross-sectional arrangement corresponding to the desired cross-section at one end of the part; moving the first of the tube end engagement structures (81) into a forced engagement with one end (40) to transform one end of the tube workpiece (40) into a shape consistent with the external configuration of the cross-sectional engagement of the first tube structure (81) an end and therefore a predetermined cross section at one end of the component; and applying pressure in the tubular blank (40) to deform it into the desired component configuration. The method of claim 3, further comprising the step of: incorporating the component into the article without cutting one end of the forced engagement component with the first of the tube engagement structures (81). Assembly according to claim 1, characterized in that the first of the tube engagement structures (81) has a front end (33) and a side shoulder (88) extending from the polygonal portion (84) such that the first of the structures (81) For engaging the tube, it may be inserted into the tubular blank (40) continuously from the front end (33) of the tube engagement structure to the side shoulder (88) along the polygonal portion (84) until the side shoulder (88) abuts and stops the next insertion. a structure (81) for engaging the pipe relative to the tubular blank (40). The method of claim 3, wherein moving the first of the tube engagement structures (81) comprises inserting the first of the tube engagement structures (81) into the tube. REPLACEMENT SHEET • 4 ·· 44 4 · • 4 4 4 4 4 4 44 44444 44 4 44 44 44 444 44 4444 4444 44 44 ·· ·· 16041 -19 of the blank (40) continuously from the front end (33) of the first of the tube engagement structures (81) along the polygonal portion (84) of the first of the tube engagement structures (81) for lateral shoulder (88) of the first of the structures (81) ) for engaging a tube extending from the polygonal portion (84) until the side shoulder (88) abuts the end of the tubular blank (40) and stops further insertion of the tubular engagement structure (81) relative to the tubular blank (40). The method of claim 3, wherein moving the first of the tube engagement structures (81) into forced engagement with one end of the tubular blank (40) is completely inserting the first of the tube engagement structures (81) into the tubular blank. (40) and completely rearranging one end of the tubular blank (40) into the final, desired component configuration by fully deforming one end of the tubular blank (40) into a shape corresponding to the outer surface of the first tube engagement structure (81) and inner surface of the mold cavity ( 52).