Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D7/00—Bending rods, profiles, or tubes
  • B21D7/10—Bending rods, profiles, or tubes by abutting members and flexible bending means, e.g. with chains, ropes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D11/00—Bending not restricted to forms of material mentioned in only one of groups B21D5/00, B21D7/00, B21D9/00; Bending not provided for in groups B21D5/00 - B21D9/00; Twisting
  • B21D11/08—Bending by altering the thickness of part of the cross-section of the work
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D37/00—Tools as parts of machines covered by this subclass
  • B21D37/02—Die constructions enabling assembly of the die parts in different ways
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D9/00—Bending tubes using mandrels or the like
  • B21D9/14—Wrinkle-bending, i.e. bending by corrugating

Definitions

• the invention relates to a method for producing a bent pipe comprising at least one desired curvature, wherein a substantially straight pipe is divided into a number of segments and zones present between two successive segments.
• the invention also relates to a device suitable for carrying out such a method, as well as to a pipe produced by means of such a method.
• the dimension in axial direction of a bulge formed on an inside bend of the bent pipe to be formed is larger than that of the bulge on an outside bend of the bent pipe, it is possible to compensate for the difference in length in the inside bend and the outside bend of the bent pipe, or, in other words, the difference in radius between the inside bend and the outside bend of the bent pipe.
• a drawback of the known method is that the bulges formed in the zones form creases which extend along the entire circumference of the pipe.
• the segments located between the zones are substantially identical in shape both in the original, substantially straight pipe and in the bent pipe that is eventually formed. As a result, walls including an angle with each other are obtained in the interior of the pipe, so that an even flow is not obtained in the bent pipe when the pipe is used as a flow channel.
• the object of the invention is to provide a method by means of which a pipe can be given practically any curvature, whilst an even transition between the segments is obtained.
• each segment of the substantially straight pipe is provided with a local curvature of the segment in question of the bent pipe eventually to be formed, whereupon all segments of the substantially straight pipe are pivoted relative to each other so as to form the bent pipe, with the bent pipe exhibiting the desired curvature.
• the local curvatures in the pipe wall are determined for every segment of the bent pipe, along the entire circumference of said pipe.
• a substantially straight pipe is theoretically divided into said segments, and the walls of said segments are given the local curvatures. Since the segments form part of a curvature, for example a circular arc or a differently configured bend, zones will be present between the segments, at least on inside bend of the curvature to be formed, when a substantially straight pipe is divided into said segments.
• the segments are moved towards each other, with the local curvatures of the adjoining segments becoming aligned and the, preferably contiguous, local curvatures forming a continuous curvature in the bent pipe.
• pipe as used herein is understood to mean a tubular section having a circular or other cross-section, which may be constant or change in the longitudinal direction of the pipe.
• the device that is used for this purpose comprises a number of pivotally interconnected parts, which number preferably corresponds to the number of segments of which the curved pipe is formed.
• One embodiment of the method according to the invention is characterised in that the local curvature of a segment of the substantially straight pipe has a smaller radius on an inside bend of the curvature to be formed than on an outside bend of the curvature to be formed.
• both the inside bend and the outside bend will have obtained the radius associated with the respective inside bend and outside bend after the substantially straight pipe has been bent to form the bent pipe.
• Another embodiment of the method according to the invention is characterised in that the internal wall on the outside bend of the curvature of the bent pipe is substantially smooth.
• each segment of the original straight pipe with a local curvature, at least on the outside bend of the curvature to be formed, which curvature corresponds to the eventually desired curvature of the bent pipe, the outside bend part of the bent pipe that is eventually formed will be substantially completely smooth.
• the interior of the pipe will be substantially completely smooth as well, thus enabling a smooth flow through the bent pipe.
• Yet another embodiment of the method according to the invention is characterised in that a segment of the substantially straight pipe tapers off from an inside bend of the curvature to be formed to an outside bend of the curvature to be formed.
• a bent pipe will be obtained when the sides of the segments facing the inner side are moved together, in which bent pipe the segments are substantially contiguous.
• Another embodiment of the method according to the invention is characterised in that a zone comprises a part of the straight pipe that can be creased between two successive segments, each zone in the bent pipe being folded into a crease.
• the crease is larger near the inside bend than near the outside bend, and gradually decreases in size in the circumferential direction of the pipe. Creases need not be formed near the outside bend, since the segments can directly join one another at that location. As a result of the presence of the aforesaid creases, hardly any stretch will occur when the material is being bent. As a result, also materials having a low plastic deformation capability, to be expressed in elongation at break, for example, can be used for producing bent pipes. Think in this connection of materials such as steel, aluminium and other metals or plastics.
• Yet another embodiment of the method according to the invention is characterised in that a beginning of a crease is formed in each zone of the substantially straight pipe.
• each zone will be creased to the desired configuration when the substantially straight pipe is bent to form the bent
• Yet another embodiment of the method according to the invention is characterised in that the substantially straight pipe is positioned in a number of pivotally interconnected parts, each part comprising at least one curvature to be locally provided of a segment positioned therein, whereupon the pipe is deformed, during which deformation each segment is pressed against the wall of the associated part, as a result of which the segment is provided with the local curvature, and the parts are subsequently pivoted relative to each other, thus forming the desired curvature in the pipe.
• Creases may be formed in the zones between the parts, if desired.
• Figure 1 shows a theoretical model of a bent pipe
• Figure 2 shows the bent pipe of figure 1, divided into segments
• Figure 3 shows the bent pipe of figure 2 developed along a line
• Figure 4A shows a theoretical model of the substantially straight pipes comprising removed zones that is to be formed
• Figure 4B shows a detail of the substantially straight pipe shown in figure 4A;
• Figure 5 shows a theoretical model of the substantially straight pipe comprising removed zones that is to be formed, in which zones to be creased are present between the segments;
• Figures 6A-6L and figures 7A-7E show various views of the forming of a bent pipe from a substantially straight pipe
• Figures 8A-8C show a perspective front view, a perspective top plan view and perspective side view, respectively, of another bent pipe according to the invention.
• Figure 9 shows a perspective front view, a perspective top plan view and perspective side view, respectively, of yet another bent pipe according to the invention.
• Figure 10 shows a perspective front view, a perspective top plan view and perspective side view, respectively, of yet another bent pipe according to the invention
• Figures liA and nB show a perspective view and a top plan view, respectively, of a device according to the invention
• Figures 12A and 12B show top plan views of a device according to the invention with a substantially straight pipe and a bent pipe formed by means of the device, respectively, present therein.
• Figure 1 shows a theoretical model of a bent pipe 1 which extends along an axis 2.
• the bent pipe 1 has a circular cross-section.
• the bent pipe 1 has an inside bend 3 with a radius Ri as well as an outside bend 4 with a radius R ⁇ , wherein R,, > R ; .
• Figure 2 shows the bent pipe 1 of figure 1, in which the bent pipe 1 is divided into segments S t , S 2 ...S n formed by lines 5 which extend from the centre M of the radii R ; and Each segment S submit S 2 ...S n extends through the same angle a.
• Each segment S lf S 2 ...S n has an inside radius R ⁇ ,
• Segment S j is bounded by the angular points aont and a ! on the outside of the bend and angular points b 0 and b, on the inside of the bend.
• Segment S 2 is bounded by the angular points a i; a 2 , b draw b 2 .
• the angular point a. x thus forms an angular point both of the segment S j and of the segment S 2 .
• the angular point b j forms an angular point of the segments S j and S 2 .
• Figure 3 shows the bent pipe 1 shown in figure 2, in which the segments S j - S 4 have been pivoted away from each other, such that the angular points a 0 , auß a 2 , a 3 , a 4 lie on a straight line L.
• the opposite longitudinal sides 7, 8 of adjacent segments S p S 2 include the angle a with each other.
• each segment S die S 2 .... S n has an inside radius R j ,, R j2 Rj n and an outside radius R ol R O2 ..R On . Because the segments S i; S 2 have been pivoted away from each other, the angular point b j , is no longer a common angular point, but it is now formed by two angular points b,.
• Figure 4A shows the bent pipe 1 fully developed into a substantially straight pipe 10, in which all the angular points a 2 a s lie on the line L. Zones Z lf Z 2 .... Z n are present between the adjacent segments S j , S 2 .... S n , which zones are not filled in the substantially straight pipe 10 that is shown in figure 4.
• Figure 4B shows a larger-scale detail of segment S 3 , in which the outside radius can be clearly distinguished.
• Figure 5 shows a substantially straight pipe 11, which is different from the straight pipe 10 shown in figure 4A in that, in contrast to figure 4, the zones Zdon Z 2 Z n _, present between the segments Shiel S 2 S n are filled.
• Figures 6A-7E show the deformation of a cylindrical pipe 21 having a constant diameter over its entire length, via a substantially straight pipe 22 that is divided into segments and zones present therebetween, into a bent pipe 23.
• the cross-sectional shape of the pipe 21 is changed from a cylindrical cross-section with a constant diameter to a cross-sectional shape that changes along the length of the pipe from triangular into cylindrical.
• Figure 6A shows a longitudinal section of the substantially straight pipe 22, which has been divided into a number of segments S 1 S 2 S n and zones Z 2 Z n present therebetween in the above-described manner, on the basis of the desired curvatures in the bent pipe to be formed.
• zone Z extends less far towards the wall 24 that is to form the outside bend than the zone Z n .
• the segments S 1 S 2 S n have a curvature with a radius R ⁇ , R on at the wall 24. If all the radii are identical, the outside bend of bent pipe to be formed will be circular in shape. It is also possible for the radii to change gradually, to that the final bent pipe 23 will have a curvature different from a circular arc. The same applies, of course, with regard to the wall 25 of the substantially straight pipe 22 that is to form the inside bend.
• Each zone Z Center Z 2 Z n . has an outwardly projecting bulge 26 in the wall thereof, whose degree of bulging varies along the circumference of the substantially straight pipe 22.
• the substantially straight pipe 22 with the segments S 2 S n formed therein and the zones Ztent Z 2 Z ⁇ present therebetween can be formed by means of a hydroforming technique.
• this technique which is known per se, the cylindrical pipe 21 is placed in a space present in a device. Said space is bounded by walls comprising a profile corresponding to the profile to be formed in the substantially straight pipe 22 that is to be produced.
• a fluid such as oil
• the pipe 21 is deformed to obtain the substantially straight pipe 22 comprising the segments, the zones and the curvatures and bulges formed therein.
• the straight axis of the pipe 21 is substantially identical to the axis of the substantially straight pipe 22 with the local curvatures formed in the segments.
• the pipe 22 is bent to form the bent pipe 23.
• Said bending comprises moving the segments S submit S 2 S n towards each other on a side facing the wall 25, causing the zones Zender Z 2 Z n ., to be folded together, resulting in the formation of a crease 27 (see figure 6E).
• the wall 25 that forms the inside bend comprises the substantially contiguous segments S 1? S 2 S n , with the local curvature with radii R ⁇ , forming a substantially continuous internal wall 28, which is interrupted only by the creases 27.
• the segments S 17 S 2 S n join one another in a perfectly contiguous manner at the wall 24, so that a substantially completely smooth inner wall is obtained.
• the central axis of the bent pipe 23 has a curvature with the same centre of curvature as the outside bend of the bent pipe 23.
• FIGE1 and figure 6E2 show the same view of the bent pipe 23 but with different details VID, VIE and VIH, VIL, VIK, respectively.
• figure 6F and figure 6G show a side view of the substantially straight pipe 22 and the bent pipe 23 formed therefrom, respectively.
• each crease 27 formed by zone Zdon Z 2 ?? Z n _ do not extend along the entire circumference of the bent pipe 23. Moreover, each crease 27 decreases in size, seen in circumferential direction from the inside bend to the outside bend.
• Figures 8A-8C show another bent pipe 31 formed by using the method according to the invention, which pipe is provided with identical cylindrical openings 32, 33 at both ends and which comprises a part 34 having a triangular cross-section near the centre.
• the bent pipe 31 comprises a first bent part 35, which extends between the circular passage 32 to the part 34 with the triangular cross-section, and a second bent part 36, which extends from the part 34 with the triangular cross-section to the circular passage.
• Such a pipe 31 is for example obtained by providing inter alia the segments and zones desired for the bent parts 35, 36 in a straight pipe. Then the substantially straight pipe thus formed is bent in a number of steps to obtain the desired bent pipe.
• Figures 9A-9C show another embodiment of a bent pipe 41 which is different from the bent pipe 31 shown the in figure 8A-8C in that the circular passages 42, 43 at the ends of the bent pipe 41 are different in diameter.
• Figures 10A-10C show yet another embodiment of a bent pipe 51 according to the invention, which comprises two bent parts 52, 53 and a part 54 with a triangular cross-section, which extends therebetween.
• a cylindrical pipe 55 which has a larger diameter near the end 56 than near the bent part 53 and the other end 57, joins the bent part 53.
• Figures 11A and 11B show a perspective view and top plan view, respectively, of a device 61 according to the invention, which is suitable for producing the bent pipe 23, for example.
• the device 61 comprises two parts 62, 63 to be positioned opposite each other, which are each provided with parts 65 interconnected via pivot arms 64.
• Mating parts 65 of the lower part 63 and the part 62 positioned thereabove jointly define a passage 66, whose wall 67 is provided with local curvatures which correspond to curvatures to be formed in a segment S braid S 2 S n .
• the operation of the device 61 is as follows.
• the upper part 62 is removed from the lower part 63, whereupon a pipe 21 is placed in the passages 66.
• the upper part 62 is positioned over the straight pipe 21.
• fluid pressure is applied in the pipe 21, whilst at the same time axial forces are exerted on the ends of the pipe 21.
• the wall of the pipe 21 is deformed, and the curvatures are formed in the segments S,,
• Figures 12A-12B show a similar device 71 according to the invention, which is provided with supports 72, 73 at both ends.
• the parts 65 are pivoted relative to each other in the directions indicated by the double arrow, as a result of which the substantially straight pipe 22 is bent to obtain the bent pipe 23. Since the segments S i; S 2 S n firmly abut against the walls 67 of the passages 66 during said bending, the segments S iy S 2 S n will not deform.
• the hydraulic pressure applied by the fluid may or may not be maintained during the bending of the substantially straight pipe to form the bent pipe.
• the angle is the same for all the segments S 1 ⁇ S 2 S n It is also possible, however, to have the segments S 1 ⁇ S 2 S n extend through different angles a lt a 2 a n .
• the forming of the segments and zones in the pipe can take place not only by hydroforming but also by means of explosion transformation, rubber pressing, hot forming, etc.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Bending Of Plates, Rods, And Pipes (AREA)

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• 2009
  • 2009-10-19 ES ES09743956.6T patent/ES2490365T3/es active Active
  • 2009-10-19 EP EP09743956.6A patent/EP2490833B1/de not_active Not-in-force
  • 2009-10-19 PL PL09743956T patent/PL2490833T3/pl unknown
  • 2009-10-19 WO PCT/NL2009/050630 patent/WO2011049432A1/en not_active Ceased

Non-Patent Citations (1)

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