EP4046725A9 - Procédé de fabrication d'un rétrécissement étagé de la section transversale dans une pièce tubulaire monobloc métallique, pièce tubulaire monobloc métallique ainsi fabriquée et dispositif de mise en uvre du procédé - Google Patents

Procédé de fabrication d'un rétrécissement étagé de la section transversale dans une pièce tubulaire monobloc métallique, pièce tubulaire monobloc métallique ainsi fabriquée et dispositif de mise en uvre du procédé Download PDF

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Publication number
EP4046725A9
EP4046725A9 EP22156995.7A EP22156995A EP4046725A9 EP 4046725 A9 EP4046725 A9 EP 4046725A9 EP 22156995 A EP22156995 A EP 22156995A EP 4046725 A9 EP4046725 A9 EP 4046725A9
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EP
European Patent Office
Prior art keywords
tubular workpiece
forming
workpiece
ring
guide
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.)
Pending
Application number
EP22156995.7A
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German (de)
English (en)
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EP4046725A1 (fr
Inventor
Michael Roderich
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.)
GFU Maschinenbau GmbH Gesellschaft fuer Umformung und Maschinenbau
Original Assignee
GFU Maschinenbau GmbH Gesellschaft fuer Umformung und Maschinenbau
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 GFU Maschinenbau GmbH Gesellschaft fuer Umformung und Maschinenbau filed Critical GFU Maschinenbau GmbH Gesellschaft fuer Umformung und Maschinenbau
Publication of EP4046725A1 publication Critical patent/EP4046725A1/fr
Publication of EP4046725A9 publication Critical patent/EP4046725A9/fr
Pending legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
    • B21K21/00—Making hollow articles not covered by a single preceding sub-group
    • B21K21/16—Remodelling hollow bodies with respect to the shape of the cross-section
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C5/00—Pointing; Push-pointing
    • B21C5/003—Pointing; Push-pointing of hollow material, e.g. tube
    • 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
    • B21D41/00—Application of procedures in order to alter the diameter of tube ends
    • B21D41/04—Reducing; Closing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
    • B21K21/00—Making hollow articles not covered by a single preceding sub-group
    • B21K21/12—Shaping end portions of hollow articles
    • 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
    • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
    • B21D22/14—Spinning

Definitions

  • the present invention relates to a method for producing a stepped cross-sectional taper on a one-piece tubular metal workpiece according to claim 1, a one-piece tubular workpiece produced therewith according to claim 8 and a device for carrying out the method according to claim 9.
  • the method according to the invention can, for example, are used to produce the following one-piece components from tubular workpieces, but is not limited to this: rotor shafts, drive shafts, shaft journals, stabilizers, shafts of all kinds that have a steep transition in the area of the cross-sectional reduction, scaffolding supports, scaffolding frames for the construction industry and tie rods.
  • Forming methods for tubular workpieces are known from the prior art, in which the tubular workpiece undergoes a significant reduction in wall thickness in the area of the stepped cross-sectional reduction due to the forming process.
  • the reduction in wall thickness in the forming area is inevitably accompanied by a reduction in the mechanical stability of the formed workpiece.
  • the step-shaped cross-sectional reduction is designed as an approximately right-angled stop edge.
  • DE 10 2012 110 792 A1 the same applicant is known for this purpose a method can be produced with the right-angled step-shaped transitions. In this way, a reduction in the wall thickness in the transition area can be avoided.
  • the known method necessarily provides for a preceding axial upsetting step before the step-shaped transition is formed, in order to increase the wall thickness of the workpiece in a deformation area.
  • the object of the present invention is therefore to specify a forming method for producing a cross-sectional reduction on a tubular workpiece, with which a right-angled or almost right-angled shoulder (stepped transition) can be produced, which is highly resilient and in particular withstands alternating bending stress and torsional stress.
  • the method should manage without an additional upsetting step before forming the shoulder, in which the wall thickness of the tubular workpiece in the forming area before forming the shoulder increases by at least 30%, preferably at least 20%, by axial upsetting.
  • the shaped workpiece produced with the method according to the invention and a device suitable for carrying out the method according to the invention are to be provided.
  • tubular workpiece includes any shape of an elongate hollow body, preferably a tube, the length of which is greater than its outside diameter.
  • the cross-sectional shape of the tubular workpiece is not limited to a circle, but may be elliptical or circular-like.
  • the term “in one piece” in relation to the tubular workpiece means that this has at most a longitudinal weld seam, but otherwise no weld seam and no joining seam. According to the invention, the term “in one piece” preferably means that the tubular workpiece has no weld seam and no joint seam.
  • reducing the cross section” or “tapering the cross section” of a tubular workpiece include a reduction in the diameter of the tubular workpiece at least in sections.
  • cross-sectional tapering is understood to mean a transition from a section of the tubular workpiece with a larger diameter to a section of the same with a smaller diameter.
  • a section of the tubular workpiece that has a smaller diameter after the forming according to the invention and the transition to a section of the tubular workpiece with a larger diameter is referred to as the "forming area”.
  • the section of the tubular workpiece which is the transition from the section of the tubular workpiece with the smaller diameter to the section of the tubular workpiece with the larger diameter is referred to according to the invention as the "transition area".
  • the transition area is part of the forming area.
  • the forming area is a continuous section of the tubular workpiece which, due to the forming according to the invention, has a reduced diameter compared to the state before forming or compared to the original diameter of the workpiece in the same area.
  • metal includes an element belonging to the metals, such as iron or non-ferrous metals, such as copper, alloys of two or more metals, such as stainless steel, or other alloys with a metal content of > 90%, such as steel. According to the invention, the definition of the term “metal” also includes an element or an alloy which has a proportion of technically unavoidable impurities.
  • terms such as “approximately” or “almost” in relation to a numerically definable or defined parameter mean a deviation of at most 5%, preferably at most 3%, from the stated numerical value.
  • the terms “approximately” or “almost” mean a deviation of at most 3°, preferably at most 2°, in particular at most 1°, from the stated angle.
  • a one-piece, formed workpiece with a steep shoulder is achieved by the method according to the invention.
  • a large variety of tubular workpieces of different diameters and lengths can be formed with the method according to the invention.
  • tubular workpieces with a length of 150 to 4,200 mm can be processed according to the invention.
  • the position of the shoulder along the length of the tube can be chosen freely, which underlines the high flexibility of the method according to the invention.
  • the workpiece formed according to the invention has a homogeneous fiber structure due to the lack of a welding or joining seam (the workpiece can at most have a longitudinal welding seam), which leads to greater internal material stability.
  • the particular advantage of the method according to the invention is that the interaction of the first stuffing pot ST1, the first stuffing ring SR1, the first stuffing guide SF1 and the first inner mandrel ID1 during the shaping of the tubular workpiece W in step (c) causes a shaping (formation of the shoulder S in the transition area T) and an upsetting of the workpiece W in the transition area T is achieved in a single step.
  • the material flow is directed in a targeted manner in order to achieve the desired contouring and wall thickening of the workpiece in the transition area during forming.
  • the first stuffer box ST1, the first upset ring SR1 and the first upset guide SF1 due to their predetermined inner diameter, prevent the material of the workpiece from bulging or flowing outwards in an uncontrolled manner.
  • the presence of the inner mandrel with its predetermined outer diameter inside the workpiece during step (c) prevents uncontrolled collapse or inward flow of the material of the workpiece.
  • step (d) is provided, in which the shoulder produced in step (c) is made steep up to a tangent angle of 90°, because the enlarging of the wall thickness in step (c), in step (d) a steep shoulder is obtained with a wall thickness which is 1.01 to 1.6 times the wall thickness of the tubular workpiece at the same location on the workpiece before forming in step ( c) corresponds.
  • the tubular workpiece W has a wall thickness in the transition area T after the forming according to step (c) that is greater than the wall thickness of the workpiece W at the same point before the cross-sectional reduction according to step (a) (i.e. before the cross-section reduction was carried out) is not reduced or even increased. This achieves even better mechanical stability of the formed workpiece in the transition area. It is even more preferred if the tubular workpiece W in the transition region T after the forming according to step (c) has a wall thickness that is 100 to 160%, in particular 101 to 150%, of the wall thickness of the workpiece W at the same point before the cross-sectional reduction according to step (a) is.
  • Step (c) of the method according to the invention thus completes several tasks at the same time in one step: on the one hand, the shoulder S is formed with a tangent angle (a) of 45 to ⁇ 90° from the cross-sectional reduction in the transition area, while on the other hand a material reserve is created in the transition area which, in a further, optional forming step (cf. step (d) described below) allows a steep position of the shoulder without causing a further significant change in the wall thickness of the workpiece in the transition area, i.e. neither thickening nor thinning of the wall of the workpiece in the transition area compared to the original wall thickness.
  • step (c) Since in the first forming step (step (c)) the shoulder S is only formed up to a tangent angle of ⁇ 90°, preferably up to 80°, and not a full right angle, crack formation at the step attachment on the inside of the workpiece in the transition area T, as explained in more detail below, effectively avoided.
  • step (a) The reduction of the cross section of the tubular workpiece in step (a) can be accomplished according to the invention by drawing in, kneading or similar process techniques of plastic metal forming known to those skilled in the art. Reducing the cross-section by drawing in (axial forming) is preferred because this does not require the workpiece to be heated.
  • step (a) of the method according to the invention it can be provided that the forming region U, preferably the tubular workpiece W, is not heated to 80° C. or more, preferably to 40° C. or more, before and during the reduction.
  • the reduction of the cross section in step (a) can take place in one or more partial steps or strokes.
  • a further reduction of the cross section of the tubular workpiece W in the forming region U of the tubular workpiece W can be provided in step (a). This can be provided above all if a step S with relatively large dimensions in the radial direction is to be produced (further reduction in the transition area), or if the workpiece is to have two or more steps at different points in the forming area (creation of several step jumps).
  • a reduction in the workpiece diameter of around 20 to 35% is possible with a single reduction step or stroke.
  • a further stroke or several further strokes can be carried out to reduce the cross section.
  • a second forming tool UW2 or several further forming tools can be used to further reduce the cross section of the tubular workpiece.
  • the transition area T is part of the forming area U and forms the transition from the original, non-reduced cross section of the tubular workpiece W at one end of the transition area T to a section of the forming area U with a reduced cross section or diameter at its other end.
  • step (b) is necessary in the context of the process according to the invention, since otherwise step S is not possible in step (c) and possibly in further steps can be designed as sharp-edged as desired and/or crack formation in the transition area T is to be feared.
  • the inventors have observed what is known as flaking or abrasion on the surface in the transition region T during cold forming below the temperature range specified in step (b), in particular below 700.degree.
  • heating the workpiece or the transition area thereof to a temperature of over 1,450 °C is harmful, since the workpiece almost begins to melt and critical structural changes (coarse grain) can occur or defined forming is no longer possible.
  • the tubular workpiece W Before the tubular workpiece W is formed in step (c) (and thus also before and during steps (a) and (b)), the tubular workpiece W can be axially upset, the wall thickness of the tubular workpiece W being reduced in at least one section of the forming area U increases by at least 30%, preferably at least 20%.
  • the method steps of upsetting and, if necessary, the local heating of the workpiece required for this are saved compared to the conventional methods, as a result of which the method can be carried out in a shorter time and with less energy and costs.
  • the first upsetting ring SR1 has a contour on the inner peripheral surface which preferably has a rotationally symmetrical upsetting edge, the tangent of which to the stroke direction or to the central axis MW of the tubular workpiece W during the forming in step (c) is at an angle of 45 to ⁇ 90 °, preferably 65 to 75 °.
  • the first stuffer box ST1, the first stuffer ring SR1 and the first stuffer guide SF1 can each be made in one piece, in two pieces, in three pieces or from even more pieces.
  • the first stuffer box ST1 can be designed in one piece.
  • the first compression pot ST1 is preferably designed in two or more parts, which simplifies the attachment of the tool to the workpiece to be formed.
  • the first compression ring SR1 and the first compression guide SF1 can each be designed in two or more parts, which makes it easier to replace the respective part.
  • the first upsetting ring SR1 and the first upsetting guide SF1 can also be designed in one piece or be firmly connected to one another, which facilitates synchronous movement during the forming stroke.
  • the forming in step (c) can preferably be carried out by moving the first swaging ring SR1 and the first swaging guide SF1 parallel to the central axis MW of the tubular workpiece W in the direction of the first swaging cup ST1. Conversely, it is possible for the first compression pot ST1 to be moved parallel to the central axis MW of the tubular workpiece W in the direction of the first compression ring SR1. In a further, alternative embodiment, both the first compression ring SR1 (together with the first compression guide SF1) and the first compression pot ST1 can be moved towards one another.
  • the forming in step (c) can preferably be carried out until the first compression ring SR1 touches the first compression pot ST1.
  • the forming in step (c) can be carried out in particular until an end face of the first compression ring SR1 opposite the first compression pot ST1 touches an end face of the first compression pot ST1 opposite the first compression ring SR1.
  • the setting of a defined, predetermined wall thickness of the tubular workpiece in the area of the shoulder is facilitated in a structurally simple manner with the aid of the defined end point of the forming stroke.
  • the end point of the forming stroke in relation to the first compression pot ST1 and/or the first compression ring SR1 can also be fixed or determined in a manner other than the two methods described above.
  • the first compression pot ST1 preferably has a conical clearance in the form of a rotationally symmetrical recess on its end section STE1, which is arranged opposite the transition region T of the tubular workpiece W, which serve to accommodate a quantity of the metal of the tubular workpiece W during the forming according to step (c). can.
  • the provision of such a configuration advantageously allows part of the metal of the tubular workpiece W to be stored during the forming in step (c), which can then be used in a later forming step, in particular in the final formation of the shape of the Shoulder S can advantageously be used to increase the wall thickness of the tubular workpiece W in the region of the shoulder S in step (d) or in an optional burnishing step.
  • step (c) The formation of the shoulder S in step (c) is preferably followed by a further forming step (step (d)) in which the shoulder S is set up even more steeply, preferably at approximately or exactly a right angle.
  • step (d) The advantages of the two-stage shoulder formation in steps (c) and (d) are that, on the one hand, a very steep to right-angled shoulder S can be produced even with metals that are difficult to form.
  • crack formation at the shoulder on the inside of the metal in the transition area T which can occur depending on the composition, pretreatment and properties of the metal when forming a steep shoulder in a forming step, can be effectively avoided.
  • step (d) The residual heat still present in the tubular workpiece W obtained from step (c) can be utilized for the further forming according to step (d), as long as the temperature of the metal in the transition region T is between 500 and 1000.degree.
  • step (d) follows step (c) of the method according to the invention directly or only with a short delay, additional heating of the tubular workpiece W can be omitted.
  • the method according to the invention is simplified and saves more energy. Consequently, heating of the tubular workpiece W, preferably the transition region T, can be omitted between steps (c) and (d) and during step (d).
  • the second upsetting ring SR2 has a contour on the inner peripheral surface which preferably has a rotationally symmetrical upsetting edge whose tangent to the stroke direction or to the central axis MW of the tubular workpiece W during the forming in step (d) is at an angle of 80 to 90° , preferably 85 to 90°, preferably 87 to 90°.
  • the second inner mandrel ID2 can preferably have an outer diameter which corresponds to 90 to 100% of the outer diameter of the first inner mandrel ID1.
  • a square or near square shoulder can be created on the tubular workpiece by the method of the invention, it is possible to create a wide face, such as a wide fairing on a scaffold support, in the transition area.
  • the method according to the invention can also have the step: (e) before step (b), shortening of the tubular workpiece W from the end E by removing material in such a way that an axial length L of the deforming region U is set to a predetermined length, preferably +/-0.5 mm.
  • step (e) The shortening of the tubular workpiece W according to claim 3 (step (e)) enables the shoulder S to be positioned exactly from the end of the workpiece when processing tubular workpieces with a variable tube length or seamless tubes or non-drawn tubes with non-uniform wall thicknesses.
  • step (e) does not have to be carried out and can therefore be saved.
  • the tubular workpiece W of be pushed after its end E in the direction of the transition area T or in the axial direction of the transition area T.
  • the pushing can preferably be done by means of a first pipe stop RA1 (in step (c)) and/or a second pipe stop RA2 (in step (d)), with the first pipe stop RA1 preferably on the first inner mandrel ID1 and the second pipe stop RA2 preferably on second inner mandrel ID2 is attached.
  • the pushing of the tubular workpiece W from its end E in the direction of the transition region T or in the axial direction to the transition region T advantageously contributes to a thinning of the wall, i.e. a reduction in the wall thickness, of the tubular workpiece W in the transition area T, to be more precise, in the area of the shoulder S, to be prevented even better.
  • the contouring of the tubular workpiece W in the transition area T in step (g) is preferably, but not necessarily, preceded by adjusting the temperature of the tubular workpiece W in the transition area T or in a part thereof to a temperature between 350 to 1450°C.
  • the contouring forming according to step (g) can give the workpiece W its final shape of the lateral surface in the area of the shoulder S in the transition area.
  • Metal that has been carried or flowed to the outside can be transported radially inward again to form a sharp-edged, preferably right-angled shoulder S with a sufficiently large wall thickness.
  • the tubular workpiece W can be spatially fixed by a clamping tool at least during the implementation of one, several or all steps of the method, preferably radially clamped and axially held. This facilitates the execution of precise forming strokes and the automated implementation of the method according to the invention.
  • the method according to the invention is preferably carried out using the device according to the invention, as described below.
  • a one-piece, tubular workpiece W made of metal is claimed, which has been produced or can be produced using the method according to one of Claims 1 to 7.
  • the tubular workpiece W has a shoulder S in the transition area T, with a tangent WT lying at the turning point of the shoulder S making an angle of 45 to 90°, preferably 85 to 90°, preferably 87 to 90° with the central axis MW of the tubular workpiece W , in particular 89 to 90 °.
  • the tubular workpiece W preferably has a wall thickness in the transition area T, preferably in the forming area U, which is between 101 and 160%, preferably between 101 and 150%, of the wall thickness of the workpiece at the same point before the shoulder S is formed, in particular before the forming according to step (c), and/or which is between 101 and 160%, preferably between 101 and 150%, of the wall thickness of the workpiece W at a point on the workpiece W outside of the forming area U (preferably outside of all forming areas of the workpiece W, if there are several are present).
  • the tubular workpiece W has a wall thickness in the transition area T, preferably in the forming area U, which is compared to the wall thickness of the workpiece W at the same point before the cross-section reduction according to step (a) (i.e. before the cross-section reduction was carried out), and/or or which is not reduced or is even increased compared to the wall thickness of the workpiece W at a point of the workpiece W outside the forming area U (preferably outside of all forming areas of the workpiece W, if there are several). This achieves even better mechanical stability of the formed workpiece in the transition area.
  • the tubular workpiece W has a wall thickness in the transition region T, preferably in the forming region U, which is between 101 and 160%, in particular between 101 and 150%, of the wall thickness of the workpiece W at the same point before the cross-sectional reduction according to step (a), and/or between 101 and 160%, in particular between 101 and 150%, of the wall thickness of the workpiece W at a point on the workpiece W outside the forming area U (preferably outside of all forming areas of the workpiece W, if there are several) amounts to.
  • the first compression ring SR1, the first compression guide SF1 and the first inner mandrel ID1 can each be moved relative to the first compression pot ST1.
  • the first compression ring SR1, the first compression guide SF1 and the first inner mandrel ID1 are preferably separate tools compared to the first compression pot ST1.
  • the first compression ring SR1 can be connected to the first compression guide SF1 with a material, non-positive or positive connection.
  • the first inner mandrel ID1 can be movable relative to the first upset ring SR1 and to the first upset guide SF1.
  • the second compression ring SR2, the second compression guide SF2 and the second inner mandrel ID2 can each be moved relative to the second compression pot ST2.
  • the second upset ring SR2, the second upset guide SF2 and the second inner mandrel ID2 are separate tools compared to the second upset pot ST2.
  • the second compression ring SR2 can be connected to the second compression guide SF2 with a material, non-positive or positive connection.
  • the second inner mandrel ID2 can be movable relative to the second upset ring SR2 and to the second upset guide SF2.
  • the workpiece W in the forming area U can be subjected to a lubricant in order to reduce the friction when reducing the workpiece W in the forming area U.
  • the forming area U is defined as the area extending from the center of the tubular workpiece W to the end E of the tubular workpiece W, which is closer to the forming area U or from this is considered - extends from the beginning of the transition region T to the end E of the tubular workpiece W.
  • the forming strokes carried out in steps (c) and/or (d) are carried out using a force acting on the workpiece from the respective forming tool.
  • This force is preferably between 100 and 1000 kN (10 to 100 tons) for pipe diameters of 20 to 150 mm, in particular from 400 to 600 kN, with an initial diameter of the tubular workpiece W between 40 and 60 mm.
  • a tubular workpiece W made of metal is formed.
  • the tubular workpiece W can be spatially fixed in individual or all process steps, for example by means of a clamping tool or the like, preferably clamped radially and held axially, but this is omitted in the figures for reasons of clarity.
  • the 1 and 2 show a two-stage reducing of the cross section of the tubular workpiece W (step (a)).
  • a first forming tool UW1 is moved from one end E of the workpiece W parallel to the central axis MW of the workpiece W in the direction of the center of the workpiece W (cf. arrow in 1 ), resulting in a forming area U with a diameter d1 that is reduced compared to the undeformed workpiece W.
  • the forming area U is the section of the workpiece W with a reduced diameter d1 and also includes the transition area T, in which the workpiece W transitions from the initial diameter D1 to the reduced diameter d1.
  • the reduction process is analogous to that in 1
  • the step shown is carried out, but a second forming tool UW2 is used here with an inner diameter that is reduced compared to the first forming tool UW1, thereby further reducing the diameter of the workpiece W in the forming region U (diameter d2). It is not necessary to heat the workpiece W in order to carry out the single-stage or multi-stage reducing process.
  • the total length of the workpiece W increases as a result of the single-stage or multi-stage reduction process.
  • the single-stage or multi-stage reduction process as described above is not limited to the forming tool UW being moved onto the fixed workpiece W (see arrow in 1 and 2 ). It is also possible for the workpiece W to be moved onto a fixed forming tool UW.
  • the tubular workpiece W can be shortened from the end E by removing material using a corresponding tool KW such that an axial length L of the forming region U is set to a predetermined length (step (e)).
  • the removal of material can be carried out by any method known to those skilled in the art. If so-called precision tubes are used as the workpieces W, the workpiece W does not need to be shortened.
  • the workpiece W is heated to a temperature in the range from 700 to 1,450° C. in a part of the forming area U, which includes or includes the transition area T (step (b)).
  • the heating is preferably carried out by means of an induction coil IS, but can also be carried out by any other known technique.
  • step (c) of the method according to the invention is followed by the forming of the tubular workpiece W in the transition region T, as a result of which a shoulder S is formed in the transition region T ( Figure 5a , 5b and 5c ).
  • a first compression pot ST1 which is preferably designed in two parts for easier attachment, is arranged on the outer lateral surface of the tubular workpiece W before the forming in accordance with step (c) in such a way that an end face ST1SF pointing towards the end E of the workpiece is in the transition region T of the workpiece W is arranged ( Figure 5a ).
  • An inner diameter of the first stuffer box ST1 is between 100 and 110% of the outer diameter of the tubular workpiece W before the reduction of the cross section in step (a).
  • a first inner mandrel ID1 is arranged in the interior of the tubular workpiece W coaxially to the central axis MW of the tubular workpiece W before the forming according to step (c) ( Figure 5a after 5b; see arrow in Figure 5a ).
  • An outer diameter of the first inner mandrel ID1 is between 90 and 100% of the smallest inner diameter of the tubular workpiece W in the transition area T after the reduction according to step ( a) and before heating according to step (b).
  • a first compression ring SR1 and a first compression guide SF1 which are made in one piece in this example, but can also be made in several parts, for Forming moves from the end E of the workpiece W in the axial direction parallel to the central axis MW of the workpiece W onto the workpiece W (see arrow in Figure 5b ) until the first compression ring SR1 hits the end face ST1SF of the first compression cup ST1 pointing towards the end E of the workpiece W, this situation in Figure 5c is shown.
  • the first compression ring SR1 namely has a contour of its inner peripheral surface with a rotationally symmetrical compression edge suitable for forming the shoulder S.
  • the tubular workpiece W is pushed along from its end E in the direction of the transition area T or in the axial direction to the transition area T.
  • the re-pushing takes place by means of a first pipe stop RA1, this being in the Figures 5a to 5c illustrated embodiment is attached to the first inner mandrel ID1 and exerts a force in the axial direction on the end E of the workpiece W.
  • the first upsetting pot ST1, the first upsetting ring SR1 and the first upsetting guide SF1 are each arranged coaxially to the central axis MW of the tubular workpiece W on the outer lateral surface of the tubular workpiece W during the forming according to step (c).
  • An inner diameter of the first upset ring SR1 is between 100 and 115% of the outer diameter of the tubular workpiece W in the forming area U and outside the transition area T after reducing the cross section in step (a) and before heating according to step (b).
  • an inner diameter of the first Upsetting guide SF1 between 100 and 110% of the outer diameter of the tubular workpiece W in the forming area U and outside the transition area T after reducing the cross section in step (a) and before heating according to step (b).
  • the first stuffer box ST1 has a conical clearance F in the form of a rotationally symmetrical recess on its end section STE1 arranged opposite the transition region T of the tubular workpiece W.
  • This clearance serves to receive a quantity of the metal material of the tubular workpiece W during the forming according to step (c).
  • the shape of these components define a space around the workpiece (outside and inside), which allows the flow of material during Forming step (c) (combined upsetting and shoulder formation step) advantageously limited.
  • the arrangement of the first compression pot (ST1), the first compression ring SR1 and the first compression guide SF1 around the lateral surface of the workpiece W prevents or limits the material from breaking out or bulging outwards, while the arrangement of the first inner mandrel ID1 inside the workpiece W buckling or collapsing of the material into the interior of the workpiece W is prevented or limited.
  • This not only makes it possible to form a shoulder S with a turning point tangent, which encloses an angle ⁇ of about 75° with the central axis MW of the workpiece W in the present example (cf. detailed view in Figure 5d ).
  • the method according to the invention just enough material is collected in and around the transition area T in the area of the shoulder S so that the final workpiece W obtained neither shows a significant reduction nor an increase in the wall thickness in the transition area T, in particular in the area of the shoulder S , Compared to the wall thickness of the workpiece W before the formation of the shoulder S, in particular before the forming according to step (c).
  • the desired shape and wall thickness of the shoulder S by varying the shape and inner or outer diameter of the method according to the invention interacting tools, the shape of the shoulder S and the wall thickness of the formed workpiece W can be precisely adjusted in the forming area U.
  • a further forming step in which the shoulder S is placed steeply so that the turning tangent of the shoulder S encloses a right or almost right angle ⁇ with the central axis MW of the tubular workpiece W (cf. detailed view in Figure 6b ).
  • the workpiece does not have to be reheated locally. Rather, the residual heat from the preceding step (c) can be used as long as the tubular workpiece W still has a temperature in the range from 500 to 1,000° C. in the transition region T. This advantageously eliminates a further heating step.
  • the shoulder S is set steeply until a right or almost right angle ⁇ is achieved with an analog structure and arrangement of these components and execution of an analog forming stroke.
  • the second compression pot ST2 (including the end face ST2SF pointing to the end E of the workpiece) is identical to the first compression pot ST1
  • the second compression guide SF2 is identical to the first compression guide SF1, so that the corresponding components from step (c) are adopted and no additional components are required.
  • the second compression ring SR2 has a contour of the inner peripheral surface with a rotationally symmetrical compression edge that is suitable for the further steep position of the shoulder S.
  • the second compression pot ST2 also has the above-described clearance F, in which during the stroke to Steep points of the shoulder S according to step (d) a quantity of the metal material of the tubular workpiece W is added.
  • the outer diameter of the second inner mandrel ID2 is between 90 and 100% of the smallest inner diameter of the second inner mandrel ID2, at least in a section AI2 of the second inner mandrel ID2 that is arranged opposite the transition area T of the tubular workpiece W during further forming tubular workpiece W in the transition area T after forming according to step (c).
  • the workpiece W is heated to a temperature in the range from 350 to 1,450° C. in a part of the forming area U, which includes the transition area T (step (f)).
  • the heating is preferably carried out by means of an induction coil IS, but can also be carried out by any other known technique.
  • step (g)) can be followed by a rolling forming of the tubular workpiece W in the transition area T by means of at least one burnishing roller RR, here by means of three burnishing rollers.
  • the metal material previously accommodated in the clearance of the second stuffer box ST2 can again advantageously be used to strengthen the wall thickness in the transition area T or on the shoulder S.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Forging (AREA)
EP22156995.7A 2021-02-17 2022-02-16 Procédé de fabrication d'un rétrécissement étagé de la section transversale dans une pièce tubulaire monobloc métallique, pièce tubulaire monobloc métallique ainsi fabriquée et dispositif de mise en uvre du procédé Pending EP4046725A1 (fr)

Applications Claiming Priority (1)

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DE102021103689.5A DE102021103689B3 (de) 2021-02-17 2021-02-17 Verfahren zum Herstellen einer stufenförmigen Querschnittsverjüngung an einem einteiligen, rohrförmigen Werkstück aus Metall, damit hergestelltes einteiliges, rohrförmiges Werkstück und Vorrichtung zur Durchführung des Verfahrens

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EP4046725A1 EP4046725A1 (fr) 2022-08-24
EP4046725A9 true EP4046725A9 (fr) 2022-10-05

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EP22156995.7A Pending EP4046725A1 (fr) 2021-02-17 2022-02-16 Procédé de fabrication d'un rétrécissement étagé de la section transversale dans une pièce tubulaire monobloc métallique, pièce tubulaire monobloc métallique ainsi fabriquée et dispositif de mise en uvre du procédé

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Publication number Priority date Publication date Assignee Title
CN116329324A (zh) * 2023-03-11 2023-06-27 苏州祥隆泰自动化科技有限公司 冲床配套在线精密检测料厚的设备

Family Cites Families (6)

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Publication number Priority date Publication date Assignee Title
GB1472860A (en) * 1974-12-02 1977-05-11 Stevens Bullivant Ltd Metal-forming
DE10005578C2 (de) 2000-02-09 2001-09-13 Leico Werkzeugmaschb Gmbh & Co Verfahren und Drückwalzvorrichtung zum Herstellen eines Hohlkörpers
DE10245570B3 (de) * 2002-09-26 2004-03-18 Felss Gmbh Verfahren zur Herstellung eines rohrförmigen Werkstücks, insbesondere einer Stoßdämpfer-Kolbenstange, sowie ein derartiges Werkstück
DE102005012475A1 (de) * 2005-03-16 2006-09-21 IFUTEC Ingenieurbüro für Umformtechnik GmbH Verfahren zur Herstellung eines Übergangs an einem Hohlformteil
DE202008017196U1 (de) * 2008-11-12 2009-05-07 Heinrich Müller Maschinenfabrik GmbH Vorrichtung zur Rohrumformung
DE102012110792B4 (de) 2012-11-09 2016-12-01 GFU-Gesellschaft für Umformung und Maschinenbau GmbH Umformverfahren zur Herstellung einer stufenförmigen Querschnittsverjüngung an einem rohrförmigen Werkstück aus Metall

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