EP3189909A1 - Device and method for producing a lightweight metal wheel - Google Patents

Abstract

The invention relates to a device for producing a metal wheel (1) from a preform, with stretching rollers (3) acting on the rim region of the preform by means of which a rim (1.1) is finally formed, which is further characterized by below the rim flange (1.7) Stretch rollers (3) arranged, cooperating with these freely rotatable rollers (4). The invention further proposes a method for producing a metal wheel (1) from a preform, wherein the preform of the produced metal wheel (1) is placed on a mandrel (2) and rotated, in the upper region of a rotationally symmetrical shell of the preform stretching rollers (3) engage under radial pressure and move along the jacket wall of the preform under compression and stretching of the jacket wall to a rim (1.1) with a main component of movement parallel to the axis of rotation (2.1) of the preform, wherein the method is characterized in that the preform of free-rotating rollers (4) are under attack, which are arranged at the same circumferential angles as the draw rolls (3) around the circumference of the preform, so that the draw rolls form a rim flange (1.7) by stretching preform material against the underneath freely rotating rollers.

Description

The invention relates to a device and a method for producing a light metal wheel from a preform.

The invention relates to the production of light-alloy wheels, in particular made of aluminum or aluminum alloy by means of flow forming. This is a sub-form of Shear Forming, while in German different terms, such as flow (pressure) rollers, rotating rollers or draw rolls are used and here the latter term is to be used. Stretching is a non-cutting forming process for final shaping of lightweight aluminum bodies such as aluminum or aluminum alloys, particularly metal wheels.

Here, the preform of a wheel with a rotationally symmetrical sheath formation on a simple, rotating tool, a mandrel is placed, which is rotated with the preform in rotation. At the peripheral edge, a plurality of differently shaped drafting rollers engage with radial pressure on the rotationally symmetrical peripheral wall of the Preform and are moved along this, ie in an axial component during the rotation of the preform, whereby on the one hand, a compaction of the material takes place, on the other hand, this stretched by the substantially axially extending draw rolls and thus deformed and just when producing a metal wheel for Rim of the same. At the lower peripheral edge of the generally inner rim flange of the wheel to be formed is formed on a shoulder of the rotary mandrel. This processing operation, in itself a cold-forming process, can be carried out at an elevated temperature of up to 350 ° C., wherein it should be noted that heating takes place anyway by the deformation process by means of the drafting rollers alone. Such methods are basically from the US 2003/0145466 A1 or the ITVI20040061 A known.

The disadvantage is that the inner or underside of the wheel to be produced is predetermined by the shape of the mandrel and the peripheral edge of the rim flange can be optionally formed only in a complex manner by traversing the same with the drafting rollers, including the one hand complicated control operations of movement are required, on the other hand, the mandrel can disturb.

The EP 1 712 310 and the EP 1 714 714 A1 relate to the molding of a snap ring groove in the manufacture of oblique shoulder rims for trucks. Such rims are usually processed in a flow-forming process. For this purpose, a rim blank, which is usually from a rounded to a hollow cylinder and butt welded sheet metal strip, so that steel, deformed by pressing of pressure rollers. To form the snap ring groove, the workpiece is set in rotation about its longitudinal axis. The molding is carried out by deforming a groove and then by means of a - attacking from the inside - element element substantially away from the longitudinal axis of forming the end portion of the workpiece to a - provided on the outside of the workpiece wall - a predetermined groove profile exhibiting counter element. So here it takes place only a reshaping of the metal strip in the region of the snap ring groove to be formed to this.

The DE 2 053 005 and the DE 2 231 842 relate to methods and apparatus for producing Schrägschulterfelgen itself (as they are then provided according to the aforementioned publications with a groove). Here also in operation axially fixed tools on the jacket wall of the wheel to be produced and in particular - as well as in the aforementioned document - profile rollers 14, 15 from the inside at the bottom of the jacket wall for the production of the rim flange. At the time of the above two references, the flowforming process was not yet available.

The DE 103 22 752 A1 relates to a method for producing workpieces made of sheet metal with at least one branch by a forming process, among other things, rims for motor vehicles are addressed. But even here it is only about the pure forming to the effect that in the area of a previously introduced bending point by means of an attacking forming roller (2-2c) at least one wegweisender from the sheet plane flange is formed from the sheet, with areas of this flange fastened differently, so compressed should be and thus have different strength in the final product. An axial stretching along the wall of the metal jacket does not take place here either.

The WO 2005/065049 A2 refers to the production of a one-piece steel wheel. The process is multi-level and the individual stages are carried out in different form-changing processing stages. First, in a first tool, a short cylinder jacket wall is radially perpendicular over a cylindrical mandrel by radially pressurizing and axially moving rollers. Subsequently, in another step in another Werkzweug about a retracted into the interior of the cylinder barrel contoured other mandrel on this the shaping of the rim and its individual sections made by other rollers, which are also each in their working section (rim 3, tire seat 2 and 4) must move axially restricted. Regardless of the formation of the original rim bed continues to be made by other roles, the formation of the inner and outer rim flange (these two stages are preceded by further steps in turn other tools). It is essential that the rim flange is not formed by a roller in the first-mentioned stage of the stretching, but between only radially against each other engaging rollers / rollers is formed, although a non-working feed movement and the two rollers but only working radially against each oppressive.

The DE 1 452 610 relates to a method of forming an outwardly opening groove on a cylindrical tube. For this purpose, the tube is stretched in a first step by means of a first roller along the cylindrical portion of a mandrel, which has a taper at one end. To form the actual groove at the free end of the tube engage radially from the inside and from outside the taper of the mandrel, a tailstock cushion and another roll. Here, too, stretching and forming processes are separated and carried out by different tools.

The invention has for its object to provide a method and an apparatus for producing light-alloy wheels, which form better, faster and less expensive while optimizing the production, in particular the inner rim flange.

To achieve the object, the invention provides a device according to the invention with the features of claim 1 and an inventive method with the features of claim 8 before.

The device according to the invention has a mandrel and draw rolls accommodating the preform of the wheel, which initially engage in the outer region (which is placed at the top for processing) of a rotationally symmetrical shell of the preform. The drafting rollers are under radial pressure exerting under - radial - compression and - axial - stretching - the shell wall along the same movable. By means of the drafting rollers so the rim of the wheel along the mandrel is finally formed.

The mandrel inside the preform of the wheel or in the interior of the wheel to be produced is a rotationally symmetrical body and has no undercuts in the shell region, preferably the mandrel widens slightly conically from the outside of the wheel to the inside.

The mandrel must therefore not, as would be the case with undercuts, a multi-part body whose items would have to be removed to remove the wheel from him by additional hydraulic fasteners, which makes such a tool design vulnerable and also the precision of the wheel in terms of can affect important roundness and cause imbalance. The mandrel protrudes inside the produced wheel to the inside up to the height of the inner rim flange, but does not take this under.

The device according to the invention is designed in such a way that at least one of the stretch rollers acting laterally on the wheel carries out the (flow) shaping of the wheel jacket over its entire height, including the shaping of the outer side of the inner rim flange.

The forming can be done as a hot or as cold-forming, the former being used with hot preform and hot tool, the latter with cold preform and cold tool, which heat up due to the machining process in a way. The former is used in particular for cast preforms, the latter for forged preforms. I

A device according to the invention can furthermore be configured in that the freely rotating rollers have an axis of rotation inclined at an inclination angle of 50 ° to 70 ° to a rotational axis of the preform, wherein in particular the angle of inclination of the axes of rotation of the freely rotating rollers to the axis of rotation of the preform is adjustable. Further embodiments of the device according to the invention provide that the freely rotating rollers to be formed rim flange with its jacket wall engage below, in particular, the freely rotating rollers are frusto-conical and / or the shell wall of the freely rotating rollers forms an angle between 20 ° and 40 ° to the axis of rotation of the freely rotating rollers. Also, a rim end forming profile stretching roller can be provided.

The inventive method provides in a further development that the freely rotating rollers rotate about axes that include inclination angle of 50 ° to'70 ° to the axis of rotation of the preform, in particular, the free-rotating rollers engage under the lower edge of the preform with its coat, the an angle of 20 ° to 40 ° to the axis of rotation of the freely rotating rollers. In particular, it can furthermore be provided that at least one profile stretching roller for the final shaping of the rim flange engages under radial pressure exerted on the rim flange formed between draw rolls and freely rotating rolls. The invention provides in particular the possibility for a speedy, accurate and optimal design of the inner rim flange of a light metal wheel.

Fig. 1

eine Seitenansicht wesentlicher Teile einer erfindungsgemäßen Vorrichtung zum Herstellen eines Leichtmetallrades - ohne Profilstreckwalze;

Fig. 2

eine perspektivische Sicht von schräg oben auf ein Rad und wesentliche Teile der erfindugsgemäßen Vorrichtung (Profilstreckwalzen nicht sichtbar;

Fig. 3

eine Sicht auf die wesentlichen Merkmale der erfindungsgemäßen Vorrichtung perspektivisch von unten; und

Fig. 4

eine Teilansicht entsprechend der Fig. 1 mit am unteren oder inneren Felgenhorn eingreifender Profilstreckwalze.

Further advantages and features of the invention will become apparent from the claims and from the following description in which an embodiment of the invention with reference to the drawings is explained in detail. Showing:

Fig. 1

a side view of essential parts of an apparatus according to the invention for producing a light metal wheel - without profile stretching roller;

Fig. 2

a perspective view obliquely from above on a wheel and essential parts of the device according to the invention (profile stretching rollers not visible;

Fig. 3

a view of the essential features of the device according to the invention in perspective from below; and

Fig. 4

a partial view according to the Fig. 1 with engaging on the lower or inner rim flange profile stretching roller.

The Fig. 1 and 4 show a motor vehicle metal wheel 1 dashed as a preform and traced with its final contour in section ( Fig. 4 only in partial representation). The wheel 1 has a rim 1.1 and on its outside 1a a wheel disc or a spoke area 1.3 with a hub 1.4. In the inner region of the wheel disc 1.3 outside the hub 1.4 breakthroughs 1.5 are provided for attachment of the wheel by means of screws on the vehicle. The rim 1.1 has an outer rim flange 1.6 near the wheel disc 1.3 and an inner rim flange 1.7, facing away from the wheel disc 1.3, on the inside 1b.

While the outer region of the preform 1.8, in particular wheel disc or spoke region 1.3, is very close to the final shape, the jacket of the preform 1.8 extends radially, in particular in its inner region, clearly beyond the final contour of the wheel. Moreover, in the preform 1.8, the jacket extends in the axial direction only over part of the height of the finished wheel, preferably over 50% to 75%.

Furthermore, in the Fig. 1 to 4 the essential tool elements of the device according to the invention for producing such a metal wheel, in particular light metal wheel, shown from the preform, namely a simple engaging in the preform or the wheel tool 2 in the form of a mandrel, a plurality acting on the peripheral wall of the preform or the wheel different trained drafting rollers 3, the lower edge of the inner or lower edge of the rim 1.5 of the almost finished wheel 1 under cross-freely rotating rollers 4 and at least one profile stretching roller 5 (FIG. Fig. 3 . 4 ). Of the drafting rollers 3, only the directed to the wheel 1 half is shown. The draw rolls 3 are each rotatable about a substantially vertically extending axis of rotation.

The preform of the wheel 1 is seated on a simple tool in the form of a clamping mandrel 2 designed as a rotary body, which determines the inner shape of the wheel 1. The mandrel 2 is in one piece. It has no undercuts in the peripheral region and widens slightly conically from the outer side 1a of the wheel 1 to its inner side 1b, so that the finished-shaped wheel can be easily removed from the mandrel 2.

On the outer circumference of the wheel 1 engage, in particular evenly distributed over the circumference, stretching rollers 3, which, as in the left-side overlay representation of Fig. 1 represented, may be formed differently. They first attack in the upper part of the preform of the wheel 1, while exerting a radial pressure and at the same time travel along the preform of the wheel down, where they are the later Radmantel or the actual by the pressure exerted Rim 1.1 of the wheel 1 forming part 1.8 stretch the preform of the wheel down and compact at the same time.

The preform of the wheel 1 or the wheel 1 is supported on the one hand by the mandrel 2. This extends over the entire height of the wheel to be produced up to the axial height of the inner rim flange 1.7, but does not reach under the edge, the later inner rim flange 1.7 of the wheel. This is rather underrun by additional free-running roles 4. Preferably, three rollers are arranged, which are provided distributed uniformly over the circumference, in each case under a draw roller. 3

In addition, like that Fig. 3 and in particular the Fig. 4 can be seen, laterally provided in the region of the inner rim flange 1.7 to be formed circumferentially between two free-running rollers 4 at least one profile stretching roller 5, the profile of the inner rim flange 1.7 by radial pressure exerted in its circumferential groove provided on the profile 5.1. The three rotating rollers 4 are, as from the Fig. 1 it can be seen with its axis of rotation 4.1 to the axis of rotation 2.1 of the mandrel 2 and thus the rotationally fixed seated wheel 1 at an angle α of about 60 ° aligned. The freely rotating rollers 4 are formed frusto-conical and taper from its bottom to the top, wherein the jacket wall 4.2 forms an angle of 20 ° to 30 ° to the axis of rotation 4.1. The freely rotating rollers 4 engage with their jacket wall on the inside underside of the wheel 1 to form the inner rim flange 1.7. The axis of rotation of the freely rotating rollers 4.1 is freely adjustable to a certain degree, for example, between 50 ° and 70 ° relative to the axis of rotation of the 2.1 Mandrel 2, so that in this way the inner end face of the inner rim flange 1.7 can be adjusted by the angle of attack of the axis of rotation 4.1.

The manufacturing process is essentially the following:

First, the preform of the wheel 1 is poured and freed from connecting pin. Subsequently, the preform is clamped on the mandrel 2 and can be heated, ideally not to over 350 °. Then, the drafting rollers 3 move in the upper region of the preform against the same and move under the exercise of radial pressure from the outer rim flange 1.6 down to the inner rim flange 1.7, thereby forming the rim 1.1 and essentially the rim flanges 1.6, 1.7. The material of the shell of the wheel is pulled on the one hand to form the rim down in the region of the inner rim flange 1.7, so stretched, on the other hand compacts the material of the wheel. As soon as the jacket material of the wheel has been stretched to below the lower edge of the mandrel 2 by the drafting rollers 3, the freely rotating rollers 4 attack there with their jacket wall 4.2, while the profile stretching roller 4.5 engages in the space between two freely rotating rollers 4, exerts radial pressure and in its profile groove 5.1, the inner rim flange 1.7 ausform and endformt.

Claims (11)

Device designed for producing a light metal wheel (1) from a preform with a rotationally symmetrical sheath formation, wherein the preform has a in the axial direction only over a part of the height of the finished wheel (1) extending sheath extending in its inner, the outer region the wheel (1) facing away from the radially extending beyond the end contour of the wheel (1), with acting on the rim portion of the preform drafting rollers (3) exert a radial pressure on the peripheral wall and are movable along this in the axial direction such that by means of Stretching rollers (3) by stretching material of the shell of the wheel (1) a rim (1.1) of the wheel (1) is endformbar, below the draw rolls (3) freely rotatable rollers (4) at the same circumferential angles as the draw rolls to form a inner rim flange (1.7) are arranged, the freely rotatable rollers (4), the preform in the region of the rim flange (1.7) to be formed with their Ma underneath and the draw rolls under stretching of preform material against the freely rotatable rollers (4) with these to form an inner rim flange (1.7) of the wheel (1) cooperate. Apparatus according to claim 1, characterized in that the freely rotating rollers (4) have a tilt angle (α) of 50 ° to 70 ° to a rotation axis (2.1) of the preform inclined axis of rotation (4.1). Apparatus according to claim 2, characterized in that the inclination angle (α) of the axes of rotation (4.1) of the freely rotating rollers to the axis of rotation (2.1) of the preform is adjustable. Device according to one of the preceding claims, characterized in that the freely rotating rollers (4) engage under the rim flange (1.7) to be formed with its jacket wall (4.2). Device according to one of the preceding claims, characterized in that the freely rotating rollers (4) are frusto-conical. Apparatus according to claim 5, characterized in that the jacket wall (4.2) of the freely rotating rollers (4) forms an angle between 20 ° and 40 ° to the rotation axis (4.1) of the freely rotating rollers (4). Device according to one of the preceding claims, characterized by at least one profile stretching roller (5) which forms a final end of a rim flange (1.7). A method for producing a metal wheel by means of draw rolls from a preform, wherein the preform has a in the axial direction over only a portion of the height of the finished wheel extending shell, which in its inner, the outer region of the wheel remote area radially beyond the final contour of the Rades out, wherein the preform of the produced metal wheel (1) is placed on a mandrel (2), wherein in the upper region of the rotationally symmetrical shell of the preform drafting rollers (3) attack under radial pressure, wherein the drafting rollers along the shell wall of the preform with move a main movement component parallel to the axis of rotation and thereby stretch the shell wall of the preform under compression in the axial direction of the wheel jacket to a rim, wherein the preform of casing walls (4.2) freely rotating rollers (4) is under attack, the same circumferential angles as the drafting rollers (3 ) are arranged around the circumference of the preform si nd, and wherein the drafting rollers (3), together with the freely rotating rollers (4), form an inner rim flange (1.7) by stretching preform material against the undercutting, freely rotating rollers (4). A method according to claim 8, characterized in that the freely rotating rollers (4) rotate about axes that include inclination angles of 50 ° to 70 ° to the rotation axis (2.1) of the preform. A method according to claim 8 or 9, characterized in that the freely rotating rollers (4) engage under the lower edge of the preform with its jacket (4.2) which is at an angle of 20 ° to 40 ° to the axis of rotation (4.1). the freely rotating rollers (4) includes. Method according to one of claims 8 to 10, characterized in that the rim flange (1.7) formed between draw rolls (3) and freely rotating rolls (4) under radial pressure exerts at least one profile stretching roll (5) for final shaping of the rim flange (1.7).

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