Device and method for manufacturing a metal wheel

Abstract

A device for manufacturing a metal wheel (1) from a pre-form, with stretching rolls (3) engaging on the rim region of the pre-form, by means of which rolls a rim (1.1) is end-formed which, for forming a rim flange (1.7). Freely rotatable rolls (4) are arranged underneath the stretching rolls (3) and cooperate with them. A method for manufacturing a metal wheel (1) from a pre-form, the pre-form of the metal wheel (1) to be manufactured is placed on a clamping mandrel (2) and is caused to rotate, stretching rolls (3) engage an axially outer side of a rotation-symmetrical jacket of the pre-form with the exertion of radial pressure, and move along the jacket wall of the pre-form with compression and stretching of the jacket wall to form a rim (1.1) with a main movement component parallel with the axis of rotation (2.1) of the pre-form.

Claims

1. A device for manufacturing a metal wheel from a pre-form, the device comprising: stretching rolls engaging a rim region at a radially outer side of the pre-form, and said stretching rolls being displaceable radially against said outer side of the pre-form in an axially outer region of said pre-form and said stretching rolls being movable on said radially outer side of the pre-form axially along a circumferential wall of the pre-form for radial compression and axial stretching of the circumferential wall of the pre-form, wherein said stretching rolls form a rim of the metal wheel, the pre-form being rotationally symmetrical, said circumferential wall of the pre-form extending axially only along a part of the metal wheel after finishing the metal wheel, said circumferential wall having an axial inner region, said axial inner region extending radially beyond a final contour of the metal wheel after finishing the metal wheel, said stretching rolls exerting a radial force on said circumferential wall and radially compressing said circumferential wall, wherein an end of the metal wheel is formed via at least said stretching rolls stretching said circumferential wall; and freely rotating rolls for creating an inner rim flange, said freely rotating rolls being arranged underneath the stretching rolls, wherein a jacket wall of the freely rotating rolls provide abutments from underneath for the pre-form and the stretching rolls cooperate with the freely rotating rolls for forming the inner rim flange by stretching of pre-form material against the freely rotating rolls, said freely rotating rolls being arranged under an axially inner end of the pre-form.

2. A device according to claim 1, wherein the freely rotating rolls have an axis of rotation inclined at an angle of inclination from 50 to 70 to an axis of rotation of the pre-form.

3. A device according to claim 2, wherein the angle of inclination of the axes of rotation of the freely rotating rolls is adjustable to the axis of rotation of the pre-form.

4. A device according to claim 1, wherein the freely rotating rolls grip the inner rim flange to be formed from below with said jacket wall thereof.

5. A device according to claim 1, wherein the freely rotating rolls are designed in a shape of a truncated cone.

6. A device according to claim 5, wherein the jacket wall of the freely rotating rolls form an angle between 20 and 40 to an axis of rotation of the freely rotating rolls.

7. A device according to claim 1, further comprising: at least one profile stretching roll end forms the inner rim flange.

8. A device according to claim 1, wherein said freely rotating rolls provide said abutments at a height of the inner rim flange to be created.

9. A method for manufacturing a metal wheel from a pre-form, wherein the pre-form of the metal wheel to be manufactured is placed on a clamping mandrel and caused to rotate, the method comprising: providing stretching rolls, said stretching rolls engaging a radially outer side at an axially outer region of a circumferential wall of the pre-form; moving said stretching rolls axially along said radially outer side of the pre-form such that the circumferential wall is radially compressed and axially stretched from a non-stretched state to a stretched state to form a rim of the metal wheel, said circumferential wall being rotationally symmetrical, said circumferential wall of the pre-form extending axially only along a part of the metal wheel after finishing the metal wheel, wherein an end of said rim is formed via at least said stretching rolls stretching said circumferential wall, said circumferential wall having an axial inner region, said axial inner region extending radially beyond a final contour of the metal wheel after finishing the metal wheel; and gripping the pre-form from below by jacket walls of freely rotating rolls which are arranged at the same circumferential angles as circumferential angles of the stretching rolls around a periphery of the pre-form and the stretching rolls in cooperation with the freely rotating rolls form a rim flange by the stretching rolls stretching pre-form material against the freely rotating rolls gripping the pre-form from below, said freely rotating rolls being arranged under an axially inner end of the pre-form.

10. A method according to claim 9, wherein the freely rotating rolls rotate about axes which form an angle of inclination of 50 to 70 to the axis of rotation of the pre-form.

11. A method according to claim 9, wherein the freely rotating rolls grip a lower edge of the pre-form from below with said jacket walls, which forms an angle of 20 to 40 to the axis of rotation of the freely rotating rolls.

12. A method according to claim 9, wherein at least one profile stretching roll engages on the rim flange formed between said stretching rolls and said freely rotating rolls exerts a radial pressure and end-forms the rim flange.

13. A device for manufacturing a metal wheel from a pre-form, the device comprising: a plurality of stretching rolls, each of said stretching rolls being arranged at a radially spaced location from an interior space of the pre-form, each of said stretching rolls comprising a rim region contact surface for engaging a rim region of the pre-form, said rim region comprising a radially outer side, each of said stretching rolls being mounted for movement such that each of said plurality of stretching rolls engages at least a portion of said radially outer side and each of said plurality of stretching rolls moves in an axial direction with respect to a longitudinal axis of a respective one of said stretching rolls with said region contact surface in contact with said at least said portion of said radially outer side to stretch the pre-form from a non-stretched state to a stretched state; and a plurality of freely rotating rolls for creating an inner rim flange, said freely rotating rolls being arranged at a position below a position of the stretching rolls, each of said freely rotating rolls comprising a pre-form contact surface for contacting the pre-form, the stretching rolls cooperating with the freely rotating rolls for forming the inner rim flange by stretching of pre-form material against the freely rotating rolls.

14. A device according to claim 13, wherein each of said stretching rolls move radially and axially along a circumferential wall of the pre-form for radial compression and axial stretching of the circumferential wall of the pre-form, wherein said stretching rolls form a rim of the wheel, each of said stretching rolls being located at a position outside of the interior space of the pre-form, said circumferential wall comprising a non-stretched axial extent in said non-stretched state, said circumferential wall comprising a stretched axial extent in said stretched state, said non-stretched axial extent having a length that is less than a length of said stretched axial extent, said circumferential wall comprising a non-stretched inner region in said non-stretched state, said circumferential wall comprising a stretched inner region in said stretched state, wherein said non-stretched inner region extends radially beyond said stretched inner region, said circumferential wall of the pre-form being rotationally symmetrical, wherein an end of the wheel is formed via at least said stretching rolls stretching said circumferential wall of the pre-form, said freely rotating rolls being arranged at a position below an axially inner end of the pre-form.

15. A device according to claim 13, wherein the freely rotating rolls have an axis of rotation inclined at an angle of inclination from 50 to 70 to an axis of rotation of the pre-form.

16. A device according to claim 15, wherein the angle of inclination of the axes of rotation of the freely rotating rolls is adjustable to the axis of rotation of the pre-form.

17. A device according to claim 13, wherein the pre-form contact surface grips the inner rim flange to be formed from said position below said position of the stretching rolls.

18. A device according to claim 13, wherein each of the freely rotating rolls comprises a truncated cone.

19. A device according to claim 18, wherein said pre-form contact surface of each of the freely rotating rolls form an angle between 20 and 40 to an axis of rotation of the freely rotating rolls.

20. A device according to claim 13, further comprising: at least one profile stretching roll forms the inner rim flange, said at least one profile stretching roll being arranged between one of said stretching rolls and another one of said stretching rolls with respect to a circumferential direction of the pre-form.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 is a side view of essential parts of a device according to the invention for manufacturing a light metal wheelwithout a profile stretching roll;

(3) FIG. 2 is a perspective oblique elevation view of a wheel and essential parts of the device according to the invention (profile stretching rolls not visible);

(4) FIG. 3 is a perspective view from below of the essential features of the device according to the invention; and

(5) FIG. 4 is a partial view, according to FIG. 1, with a profile stretching roll engaging on the lower or inner rim flange.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(6) Referring to the drawings in particular, FIGS. 1 and 4 show a motor vehicle metal wheel 1, as a dotted line, as a pre-form and drawn with its final contour in sectional representation (only as a partial representation in FIG. 4). Wheel 1 has a rim 1.1 and at its outer side 1a a wheel disc or a spoke region 1.3 with a hub 1.4. Openings 1.5 are provided in the inner region of the wheel disc 1.3 outside hub 1.4 for fixing the wheel to the vehicle by means of bolts. Rim 1.1 has an outer rim flange 1.6 close to wheel disc 1.3 and an inner rim flange 1.7 at its inner side 1b, facing away from wheel disc 1.3.

(7) Whereas the outer region of the pre-form 1.8, particularly the wheel disc or spoke region 1.3 are already identical or at least very much approached to the final shape of the wheel the circumferential wall of the pre-form 1.8, particularly at its inner region (shown below in the drawings) extends substantially radially beyond the final contour of the wheel. Also the circumferential wall of the pre-form 1.8 extends only along a part, particularly along 50% to the 70% of the height of the final wheel.

(8) FIGS. 1 to 4 also show the essential tool elements of the device according to the invention for manufacturing such a metal wheel, particularly a light metal wheel, from the pre-form, namely a simple tool 2 engaging in the pre-form or the wheel, in the form of a clamping mandrel, a plurality of differently designed stretching rolls 3 engaging on the peripheral wall of the pre-form or wheel, freely rotating rolls 4 gripping the lower edge of the inner and inner rim edge 1.7 of the almost completed wheel 1 from below, and at least one profile stretching roll 5 (FIGS. 3, 4). Only the half of stretching rolls 3 directed toward wheel 1 is shown. Stretching walls 3 are rotatable about an essentially vertically extending axis of rotation.

(9) The pre-form of wheel 1 sits on a simple tool in the form of a clamping mandrel 2 designed as a rotary body, which mandrel determines the inner shape of wheel 1. The clamping mandrel 2 is in one piece. In the peripheral area it does not have any undercuts and increases slightly conically in diameter from the outside 1a of the wheel 1 to the inside 1b, so that the formed wheel can be easily removed from the clamping mandrel 2.

(10) Stretching rolls 3 engage on the outer periphery of wheel 1, distributed uniformly, in particular, over the circumference, which rolls, as shown in the left-side superimposed representation in FIG. 1, may be of different designs. They initially engage an axially outer side of the pre-form of wheel 1 and in doing so stretch downwards and at the same time compress part 1.8 of the pre-form of the wheel forming the subsequent wheel jacket or the actual rim 1.1 of wheel 1.

(11) The pre-form of wheel 1 or wheel 1 are supported on one side by clamping mandrel 2. However, this mandrel does not grip from underneath the edge, the subsequent inner rim flange 1.7 of the wheel. This edge is instead gripped from below by additional freely rotating rolls 4. Three rolls are preferably arranged so that they are evenly distributed over the circumference, each underneath a stretching roll 3.

(12) In addition, as shown in FIG. 3 and particularly in FIG. 4, at least one profile stretching roll 5 is provided laterally in the region of the inner rim flange 1.7 to be formed, circumferentially between two freely rotating rolls 4, which roll end-forms the profile of the inner rim flange 1.7, by the radial exertion of pressure in its profile groove 5.1 provided on the circumference. As shown in FIG. 1, the freely rotating rolls 4 are aligned with its axis of rotation 4.1 to axis of rotation 2.1 of clamping mandrel 2, and hence of wheel 1 mounted on the mandrel in a fixed position at an angle of approximately 60. The freely rotating rolls 4 are designed in the shape of a truncated cone and are reduced from their lower to their upper side, wherein jacket wall 4.2 forms an angle from 20 to 30 to axis of rotation 4.1. The freely rotating rolls 4 engage with their jacket wall against the inner-lower side of wheel 1 to form the inner rim flange 1.7. The axis of rotation of the freely rotating rolls 4.1 is to a certain extent freely adjustable, for example between 50 and 70 relative to axis of rotation 2.1 of clamping mandrel 2, so that the inner front side of the inner flange rim 1.7 can therefore be adjusted by the angle of attack of axis of rotation 4.1.

(13) The manufacturing process is essentially as follows:

(14) The pre-form of wheel 1 is first cast and freed from connecting ports. The pre-form is then clamped onto clamping mandrel 2 and can be heated, ideally not above 350 C. Stretching rolls 3 are then displaced in an axially outer side of the pre-form against the same and move, with the exertion of radial pressure, from the outer rim flange 1.6 down to the inner rim flange 1.7, thereby forming rim 1.1 and essentially rim flanges 1.6, 1.7. Here the material of the jacket of the wheel is on the one hand drawn, i.e. stretched, downwards into the region of the inner rim flange 1.7 to form the rim, and on the other the material of the wheel is compressed. As soon as the jacket material of the wheel has been stretched by stretching rolls 3 below the lower edge of clamping mandrel 2, the freely rotating rolls 4 engage at that point with their jacket wall 4.2, whilst profile stretching roll 5 engages in the interval between two freely rotating rolls 4, exerts radial pressure and forms and end-forms the inner rim flange 1.7 in its profile groove 5.1.

(15) While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.