EP2248612A1 - Procédé et assemblage de cintrage pour profilés métalliques - Google Patents

Procédé et assemblage de cintrage pour profilés métalliques Download PDF

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Publication number
EP2248612A1
EP2248612A1 EP10161942A EP10161942A EP2248612A1 EP 2248612 A1 EP2248612 A1 EP 2248612A1 EP 10161942 A EP10161942 A EP 10161942A EP 10161942 A EP10161942 A EP 10161942A EP 2248612 A1 EP2248612 A1 EP 2248612A1
Authority
EP
European Patent Office
Prior art keywords
section
bending
container
cavity
container element
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP10161942A
Other languages
German (de)
English (en)
Inventor
Timothi Faccin
Giuseppe Renaldini
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cfc Srl
Punto Curvatura Srl
Original Assignee
Cfc Srl
Punto Curvatura Srl
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Cfc Srl, Punto Curvatura Srl filed Critical Cfc Srl
Publication of EP2248612A1 publication Critical patent/EP2248612A1/fr
Withdrawn legal-status Critical Current

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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
    • B21D9/00—Bending tubes using mandrels or the like
    • B21D9/15—Bending tubes using mandrels or the like using filling material of indefinite shape, e.g. sand, plastic material

Definitions

  • the present invention relates to a bending method for metal sections and to a bending assembly for performing such method.
  • a traditional bending process does not allow the bending of sections below a predefined bending radius which varies in relation to the material and the geometry of the section.
  • Deformations of the cross-section occurring at the ends of the section are particularly undesirable.
  • the bent section is often part of a more complex structure and must be joined to segments of sections having an identical, non-deformed cross-section. Deformation of the bent section may make the join difficult if not impossible.
  • the aim of the present invention is to eliminate the problems of the prior art described above, providing a method and a bending assembly for metal sections, enabling reduction of the bending radii to obtain high quality final products in terms of dimensional tolerance and deformation.
  • a further purpose of the present invention is to provide a method and a bending assembly for metal sections, which allows the use of machinery already used in the traditional method.
  • FIG. 1a shows a flow diagram of the operating steps of the bending method according to a general embodiment of the invention
  • FIG. 1b shows a flow diagram of the operating steps of the bending method according to a preferred embodiment of the invention
  • FIG. 2 shows in perspective an open end of a container element inside of which a section to be bent has been placed upon completion of the insertion and blocking step;
  • FIG. 3 shows in perspective an open end of a bending assembly, closed by a removable closing element, upon completion of an operating step of filling the container element;
  • FIG. 4 shows a cross-sectional view of the assembly illustrated in Figure 3 , according to the cross-section plane IV - IV therein indicated;
  • FIG. 5 shows the bending step of the bending assembly illustrated in Figures 3 and 4 ;
  • FIG. 6 shows a perspective view of a container element used in the method and in the assembly according to the invention according to a preferred embodiment
  • FIG. 7 shows a perspective view of a bending assembly at the end of the bending step.
  • the method of bending metal sections according to the invention may, advantageously, be applied to any type of section, with an open or closed cross-section, made in any material, in particular stainless steel, iron, brass, aluminium.
  • the method according to the invention allows to produce high quality bent sections (in terms of precision and dimensional tolerance) with smaller bending radii than those obtained using traditional bending methods.
  • the method according to the invention allows to improve the bending quality (both in terms of precision and of reduction of the bending radius) even with sections having an open cross-section, made in materials with a low elastic limit such as aluminium, considerably reducing the risk of collapse.
  • the bending method according to the invention involves bending the metal section inside a specific container element.
  • the inner volume of such container element not occupied by the section is completely filled with molten filler material, left to solidify. As will be explained further below, such material must have a low melting point, below that of the material the section is made of.
  • the mechanical strain of bending is thus imposed directly on the container and transmitted indirectly to the inner section by the solidified filler material.
  • the deformation forces are absorbed mainly by the container element and evenly distributed over the section to be bent by the filler material.
  • the filler material by completely encompassing the section, also promotes the stress relieving of the surface material of the section itself during bending.
  • both the compression forces generated on the inner surface of the section and the drawing forces generated on the outer surface of the section are distributed over a larger area.
  • the filler material is discharged from the container element, e.g. after liquefaction.
  • the container is then cut and the bent section extracted.
  • reference numeral 1 globally denotes the container element, while P indicates the section to be bent.
  • F is the sign for the filler material.
  • bending direction is understood to mean the main direction of application of the sum of the deformation forces referred to the portion of container/section subjected to bending.
  • the plane which the overall bending line imposed on the linear element lies in (as shown in Figure 7 ) is known as the "bending plane PC".
  • the bending direction C also lies on such plane.
  • the method of bending metal sections according to the invention comprises the following operating steps:
  • the length L of the container element 10 is chosen depending on the desired bending radius R.
  • the transversal cross-section of the container element 10 is also chosen so as to permit insertion of the section P inside it.
  • the transversal cross-section of the container element is chosen depending on the transversal cross-section of the section P to be bent, so that the section P can be blocked inside the container element 10 while distanced from the inner walls of the container element 10 in the bending direction C, as shown in Figures 2 and 4 .
  • the container element 10 is chosen so that the ratio of the cross-section of the section to be bent and the cross-section of the unoccupied container, i.e. free of the section (i.e. the cross-section between the inner walls of the container and the outer walls of the section) is between 0,8 to 1,2 and preferably 1.
  • the container 10 it is in fact preferable for the container 10 not to come into direct contact with the section P along the bending direction C. In such situation mechanical strain could be concentrated on some points of the section such as to cause local yielding or uncontrolled deformation.
  • the container element 10 has a linear extension and a closed transversal cross-section. This simplifies the bending in that the closed cross-section gives the container element 10 a greater mechanical resistance to collapse than a container with an open cross-section.
  • tubular sections with an open cross-section may be used, such as C-sections.
  • the choice should be limited to sections which once closed at the ends present a support position in which they can act as containers.
  • the container element 10 must in fact be suitable for containing the filler material F in the molten state.
  • the container element 10 has a rectangular or square cross-section. This makes use of the containers simpler and easier, especially during the step of filling and solidification of the filler material F, in that they present firmer support surfaces.
  • the container element 10 is open at a first end 11 to allow insertion of the section P, as well as to facilitate emptying of the liquefied filler material F.
  • the container element 10 is provided with a first removable closing element 21 for such first end 11, as shown in Figure 6 .
  • the container element 10 is also open at the second end 12, opposite the first, and has a second removable closing element 22.
  • the aforesaid removable closing elements 21 and 22 are composed of a plate destined to engage inside the container element 10 with interference.
  • closing elements such as partitions sliding inside guides performed on the container element 10, or plugs suitable for joining to the end of the container externally by interference.
  • the container element 10 has at least one aperture 30 for casting the molten filler material F inside it.
  • the method comprises a step of shaking (i) the container element 10.
  • step is to be conducted at the same time or subsequent to the filling step (e), before solidification of the filler material F.
  • Such step has the purpose of encouraging any bubbles of air trapped inside the mass of molten material F following its casting inside the container element 10 to come out.
  • the container element 10 may be provided with a multiplicity of vent holes 31 distributed along its longitudinal extension.
  • vent holes 31 are made on the same wall which the aforesaid casting aperture 30 is made on, to prevent leakage of the molten filler material F during the filling step.
  • the section P once inserted, is blocked in position inside the container element 10 so as to be distanced from the inner walls of the container along the bending direction C.
  • the section P is blocked in position inside the container element 10, leaning against at least one wall 14 of the container element 10. As will be described further below, this makes blocking of the section P to the inside of the container element 10 more stable.
  • such support wall 14 of the container element extends on a plane parallel to the bending plane PC. In fact, this way direct transmission of the strain from the container 10 to the section P along the bending direction C and thereby harmful strain concentrated on the section P is prevented.
  • the section P is blocked inside the container element 10 by removable blocking means 40 which the container element 10 is provided with.
  • such blocking means 40 are suitable for acting on the section P in directions different to the bending direction C, so as to prevent the deformation strain from being transmitted locally in a concentrated manner onto the section P.
  • such blocking means 40 act in a direction substantially orthogonal to said bending direction C, so as to keep the section P firmly pressed against the inner support wall 14 of the container 10.
  • the aforesaid blocking means comprise a multiplicity of threaded rods 40 inserted in corresponding counter-threaded holes 41 distributed along the longitudinal extension of the container element 10 and destined to abut against the section P.
  • such holes 41 are made on the same wall which the aforesaid casting aperture 30 is made on.
  • the function of the filler material F which the inner space of the container element 10 left free by the section P is filled with, is to transmit the mechanical strain evenly to the section and, by encompassing it entirely, to encourage the stress relieving of the surface material of the section P during bending.
  • such material must have a lower melting point than the material of the section P.
  • the filler material From an operative point of view, it is preferable for the filler material to have a melting temperature of less than 100°C. In such case the liquefaction of the filler material F can be performed in a tank of boiling water. This makes both the preparation step of the material for filling the container, and the liquefying step of the material for emptying the container element 10 after bending easier and more convenient from an operative point of view.
  • the filler material F is chosen so as to have mechanical properties similar to those of aluminium.
  • the filler material F is a metal alloy.
  • the filler material F is a metal alloy comprising lead (Pb), cadmium (Cd) and/or its derivatives, tin (Sn) e bismuth (Bi).
  • This alloy has a relative density of about 9,38 g/cm 3 , a melting temperature of 70-80°C and a boiling temperature of over 1500°C.
  • the alloy is insoluble in water.
  • the solidification of the filler material F inside the container can be conducted by immersing the container 10 in a tank of water at 12°C for a period of time of about 2 hours, while its liquefaction can be achieved by immersing it in a tank of water at 90°C for a period of time of about one and a half hours.
  • this alloy is used for bending aluminium sections as it has similar mechanical properties. It can however also be advantageously used to bend sections not in aluminium, for example in iron, stainless steel and brass.
  • the bending step may be performed using any device suitable for the purpose, preferably by hydraulic bending machines N with calender rollers Q (as shown in Figure 5 ) provided with dies M to fit on said rollers.
  • the dies operate in fact on the container 10 and no longer on the section P to be bent. It is therefore sufficient to have a limited set of dies M for the types of tubular sections normally used.
  • a control step of the achieved bending radius may be foreseen. If necessary, attempts may be made to correct any imperfections using the bending machine.
  • the cutting of the container element 10 at the end of bending may be performed using any suitable instrument for the purpose, in particular using disc milling machines or cutting machines.
  • the method comprises a cleaning step (l) of the section to be performed on the bent section P extracted from the container element 10.
  • cleaning can be performed by immersing in boiling water and applying a slight surface friction to the section.
  • the bent section P is subjected to quality control, in terms of bending radius, dimensional tolerance and any defect.
  • the method according to the invention allows to bend any type of section, with an open or closed cross-section, without any limitation on the type of material.
  • sections made in material with a low elastic limit, such as aluminium, can be bent more easily and with better results.
  • the bending radius can be considerably reduced without affecting the final quality of the product.
  • the method according to the invention prevents deformations of the cross-section of the section.
  • the sections bent using the method according to the invention can thus be more easily coupled at their ends with linear elements having the same transversal cross-section.
  • the method according to the invention also permits the bending of sections which have already been painted. In fact, unlike the traditional method, the sections to be bent are no longer subjected to rubbing by the dies of the bending machines. Any surface coating or cladding is therefore not subject to damage during the bending step.
  • the method of bending metal sections comprises the operating steps of providing a container element 10, e.g. tubular or box-shaped, having a wall 14 identifying a container cavity suitable for at least partially housing a section P to be bent in at least one bending plane PC, inserting the section P in the container cavity, filling the container cavity at least with a filler material F and subjecting the container element 10 to bending, e.g. roller-bending, until the desired bending radius R is achieved.
  • a container element 10 e.g. tubular or box-shaped, having a wall 14 identifying a container cavity suitable for at least partially housing a section P to be bent in at least one bending plane PC
  • inserting the section P in the container cavity filling the container cavity at least with a filler material F and subjecting the container element 10 to bending, e.g. roller-bending, until the desired bending radius R is achieved.
  • the filling step comprises a step of also filling a section cavity, identified by the section P.
  • the bending assembly comprises a section P to be bent in at least one bending plane PC, a container element 10, e.g. tubular or box-shaped, having a wall 14 identifying a container cavity in which the section P is at least partially housed, and a filler material F filling at least the container cavity.
  • a container element 10 e.g. tubular or box-shaped, having a wall 14 identifying a container cavity in which the section P is at least partially housed, and a filler material F filling at least the container cavity.
  • the section P identifies at least one section cavity, filled by the filler material F.
  • the invention thus conceived thereby achieves the predetermined objectives.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Bending Of Plates, Rods, And Pipes (AREA)
  • Extrusion Of Metal (AREA)
EP10161942A 2009-05-06 2010-05-05 Procédé et assemblage de cintrage pour profilés métalliques Withdrawn EP2248612A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
ITBS2009A000081A IT1396151B1 (it) 2009-05-06 2009-05-06 Metodo e assieme di curvatura di profili metallici

Publications (1)

Publication Number Publication Date
EP2248612A1 true EP2248612A1 (fr) 2010-11-10

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EP10161942A Withdrawn EP2248612A1 (fr) 2009-05-06 2010-05-05 Procédé et assemblage de cintrage pour profilés métalliques

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EP (1) EP2248612A1 (fr)
IT (1) IT1396151B1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
LU84325A1 (fr) * 1982-08-06 1984-03-23 Wurth Paul Sa Procede de deformation d'objets creux ou profiles sans modification de leur section ou profil,et alliage prevu a cet effet
JPS6064733A (ja) * 1983-09-20 1985-04-13 Suzuki Motor Co Ltd パイプの曲げ加工法
FR2677564A1 (fr) * 1991-06-17 1992-12-18 Sanchez Jean Procede de cintrage de profiles metalliques.
US5907896A (en) * 1997-09-10 1999-06-01 Tseng; Shao-Chien Method for bending forging artistic metallic pipes

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
LU84325A1 (fr) * 1982-08-06 1984-03-23 Wurth Paul Sa Procede de deformation d'objets creux ou profiles sans modification de leur section ou profil,et alliage prevu a cet effet
JPS6064733A (ja) * 1983-09-20 1985-04-13 Suzuki Motor Co Ltd パイプの曲げ加工法
FR2677564A1 (fr) * 1991-06-17 1992-12-18 Sanchez Jean Procede de cintrage de profiles metalliques.
US5907896A (en) * 1997-09-10 1999-06-01 Tseng; Shao-Chien Method for bending forging artistic metallic pipes

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Publication number Publication date
IT1396151B1 (it) 2012-11-16
ITBS20090081A1 (it) 2010-11-07

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