EP1551577B1 - Method and device for the production of a pneumatic tyre rim - Google Patents

Abstract

Thus, the present disclosure includes a method of producing a weight-optimized pneumatic tire rim having rotationally-symmetrically partially different wall thickness. The steps include: providing a tube section having a first wall thickness and two end sides; leveling the first wall thickness starting from the two end sides over a defined rotationally-symmetrical area thereby forming two flanks by precontouring, each of the flanks having a second wall thickness, and pushing tolerance-caused excess material of the flanks into a well base zone between the two flanks; and contouring the flanks by pressure rolling while drawing each of the flanks toward an end area of each of the flanks and reducing the thickness of each of the flanks partially differently to predetermined measurements. The present disclosure also includes a device to implement the method.

Description

The present invention relates to a method for producing a weight-optimized pneumatic tire rim according to the preamble of claim 1 and to an apparatus for carrying out the method.

For the production of such a pneumatic tire rim, it is known, for example from DE-OS 26 47 464, on a longitudinally welded cylindrical pipe section, which is also referred to as bandage, by pressing at least one rotating spinning or stretching roller in correspondence with a tool lining the output wall thickness , So that of the pipe section, to dilute with simultaneous extension, so that partially different, functionally predetermined wall thicknesses arise over rotationally symmetric areas.

Thus, usually the rim bowl is welded to the rim base in the area of a low bed, for which purpose this must have a certain wall thickness.

Due to required weight optimization, the areas which, in contrast to said welding area, are not subject to special stress, should be formed as thin as possible, so that the original wall thickness, which is still present in the claimed tire areas in the claimed tire, by Extrusion is reduced accordingly.

However, this is associated with a number of disadvantages. For example, several operations are required to achieve the wall thickness reduction, which leads to relatively high production times and consequent high manufacturing costs.

This is also helped by the fact that the edges of the flanks are "jagged" by the extrusion, ie the stretching of the material, d. h., it creates a frayed in the broadest sense edge, which requires a post-processing.

From WO-A-96/25257 a method for producing a pneumatic tire rim is known in which the rim base is first brought to a lower wall thickness, then the ends are widened and finally the profiling is produced by a shaping roller. Such a prior art is also disclosed in US-A-5 212 866 and JP-A-59-185532.

In particular, from the viewpoint that such pneumatic rims are produced as series parts in large numbers, the disadvantages mentioned are of particular importance.

The present invention is therefore based on the object to develop a method of the generic type so that the production times are shortened and thus a more cost-effective production is possible.

This object is achieved by a method having the features of claim 1 and by an apparatus having the features of claim 8.

The pipe section used as a blank has production-related in its wall thickness relatively large tolerances, which previously led to the extrusion of a predetermined wall thickness of the flanks to the said lobes of the edges.

By contrast, the new method creates an exact, predictable material volume which is available for the further processing of the flanks (elongation, contouring and bringing to predetermined wall thicknesses).

In this case, the length extension, which results from the performed by means of flow-forming, optionally partial reduction in wall thickness, preferably limited by a stop which is provided on the circumferential surface of the WerkzeugInnenfutters circumferentially and on which the respective edge in the end position, ie after completion of the flow-forming.

Due to the volume of the flanks defined after the pressure-rolling, its length can also be determined after completion of the deformation, taking into account the desired wall thicknesses.

As a result, not only a dimensionally accurate production of the rim base is possible, but it can also be dispensed with the subsequent trimming of the edges, since the same flank volumes are present after the first process step due to the produced in each series product rim base.

The resulting from the thickness tolerances excess material is pushed in the Wandstärkenegalisierung in the deep bed zone, where it leads to a wall reinforcement.

As output wall thickness of the pipe section, therefore, one can be selected which is less than the end wall thickness in the region of the deep bed zone whose final thickness in turn results from the original wall thickness and the added tolerance material of the flanks.

According to a further aspect of the invention, it is provided that, before the equalization of the wall thickness of the then still cylindrical tube section, it is widened as an output product of this at least one, but preferably both end sides.

In this case, the diameter of the cylindrical pipe section is smaller than the largest outer diameter of the rim bed to be produced by the subsequent processing steps, whereas the diameter of the pipe section corresponds to the largest diameter of the rim well, if the end-side expansion is dispensed with.

Since the material volume of the rim remains the same in each case, a larger width or wall thickness of the pipe section is accordingly provided with a smaller diameter of the insert pipe section.

Said expansion of the pipe section has manufacturing advantages, since the subsequent pressing for contouring uncontrolled emigration of the end regions is prevented.

An apparatus for carrying out the method has the features of claim 8.

Further advantageous embodiments of both the method and the device are characterized in the subclaims.

The inventive method is described below with reference to the drawings, which show an embodiment of an apparatus for performing the method, again.

Figuren 1 und 2

eine Vorrichtung zur Durchführung eines ersten Verfahrensschritts, jeweils im Längsschnitt dargestellt,

Figuren 3 und 4

jeweils eine weitere Vorrichtung für jeweils folgende Verfahrensschritte, ebenfalls im Längsschnitt gezeigt,

Figur 5

ein weiteres Ausführungsbeispiel einer Vorrichtung zur Durchführung eines ersten Verfahrensschritts in einem schematischen Längsschnitt.

Show it:

Figures 1 and 2

an apparatus for carrying out a first method step, each shown in longitudinal section,

FIGS. 3 and 4

in each case a further device for each of the following method steps, also shown in longitudinal section,

FIG. 5

a further embodiment of an apparatus for performing a first method step in a schematic longitudinal section.

A device shown in Figures 1 and 2 for producing a weight-optimized pneumatic tire rim, in which from a cylindrical tube section 1a, preferably made of steel, by cold forming a rim base 1 with rotationally symmetrical partially different wall thicknesses, which is then connected to a rim, not shown, preferably by welding.

This device has a tool lining 2, which consists of a first chuck part 3 and a second chuck part 4, which are spring-loaded in the axial direction relative to each other.

The outer casing of the tool lining 2 is provided with a precontour 5, in which by means of pressing / rolling rollers 8 of the pipe section 1 is pressed accordingly.

From the figure 1, the beginning of the process can be seen, in which the cylindrical pipe section 1a rests on the outside of the tool lining 2.

Starting from the two end sides of the tube section 1a 8 tolerance-related excess material of a particular determined, forming a flank 6 rotationally symmetric area under equalization of the wall thickness S1 is moved by means of the pressure / rolling rollers 8 in the region of a deep bed zone 7, from which the flanks formed on both sides 6 extend under the same wall thickness S2. Both the deep bed zone 7 and the flanks 6 assume the predetermined shape of the precontour 5.

The tolerance-related excess material leads to a thickening of the wall thickness S3 of the deep bed zone 7 with respect to the original wall, while this is so far leveled in the flanks 6, that it corresponds, for example, the lower tolerance.

By way of example, a thickness of 3.5 ⁺ _- 0.1 is given as the initial wall thickness of the tubular cylinder 1a, so that the wall thickness S2 of the flanks 6 is 3.4, while the wall thickness S3 of the deep bed zone 7 can be about 3.85. Here, the leveling of the wall thickness in the region of the flanks 6 has led to a thickening of the deep bed zone 7 with respect to the original material used.

In order to keep the pipe section 1a in the axial direction and to prevent that an axial stretching takes place during rolling, both the first chuck part 3 and the second chuck part 4 have a circumferential stop 9, on which first the pipe section 1a and subsequently Course of the process, the pre-contoured rim base 1 end supports.

According to the length shortening of the tube section 1a, which takes place by the precontouring, the second chuck part 4 is tracked with spring force until it reaches an end position, as shown by dashed lines in FIG. 1 and as shown in FIG.

In the following method step, the flanks 6 are contoured further under extension to the outside, as can be seen in FIG.

Here, another tool lining 2a is shown, the first and second chuck part 3a and 4a with respect to the first and second chuck part 3 and 4 of Figures 1 and 2 have a modified and stretched course of the contour 5a.

By means of this device, which has at least one pressing / rolling roller 8, the respective different wall thicknesses of the flanks 6 can be produced.

By extension, one of the two flanks 6, starting from the deep bed zone 7, is brought to a wall thickness S4 by means of the pressing / rolling roller 8 which presses from the inside to the outside, which can be 2.6, for example, with reference to the previous dimensions.

The opposite flank 6, however, is stretched so far that within the flank 6, a rotationally symmetric region with the wall thickness also S4 = 2.6 and another area with the wall thickness S5 = 1.8 results.

The end of the deformation of the flanks 6 is limited by stops 9a, which are provided circumferentially on the first and second chuck part 3a and 4a and respectively form the conclusion of the contour 5a.

The volume which can be exactly determined beforehand by the leveling of the flanks 6 can again be found in the now larger axial extent and the partially partially reduced wall thickness.

In any case, the height of the rim base 1 and the wall thicknesses of the flanks 6 are exactly predictable.

In a subsequent further processing of the rim base 1, as shown in FIG. 4, the end regions of the flanks 6 are finished by shaping rollers 10. In a manner known per se circumferential rim flanges 11 and humps 12 (humps) are formed, which serve to receive a tire.

Here, too, a tool lining 2b is provided, which consists of a first chuck part 3b and a second chuck part 4b, which are externally formed at least partially corresponding to the contour of the rim base 1.

In the figure 5 it can be seen that the largest diameter of the chuck parts 3, 4 in the processing area or in the contact area with the pipe section 1a is greater than the clear diameter of the pipe section 1a, so that the first cylindrical pipe section 1a with its end edges at the respectively associated Vorkontur 5 of the chuck parts 3, 4 is present.

With an axial feed of the chuck parts 3, 4 to one another, the end regions of the tube section 1a are respectively deformed into a widening 1b.

The further processing, that is, the contouring in the end regions, as described, by means of the pressing / rolling rollers. 8

LIST OF REFERENCE NUMBERS

1

rim

1a

pipe section

1b

widening

2

Tool lining

2a

Tool lining

3

first food part

3 a

first food part

4

second feed part

4a

second feed part

5

precontour

5a

contour

6

flank

7

Deep bed zone

8th

Push / roll-roll

9

attack

9a

attack

10

forming roller

11

rim flange

12

humpback

Claims (12)

1. Method for production of a weight-optimized pneumatic tyre rim, in which

   a. a rim bed (1) having partially different wall thicknesses in terms of rotational symmetry is produced by cold-forming from a tubular portion (1a) preferably produced from a welded tube, and

   b. is subsequently connected to a rim bowl,
   characterized in that

   c. the wall of the tubular portion (1a),

   ■ starting from the two end faces,

   ■ in each case over a specific rotationally symmetrical region which forms a flank (6),

   is brought to a largely exact wall thickness (S2), so as to form a precontour,

   d. the tolerance-induced excess material of the flanks (6) being pushed into a deep-bed zone (7) between the two flanks (6),

   e. and, thereafter, the flanks (6) being contoured by pressure rollers, along with elongation toward the free edge region, and being reduced in their thickness (S4, S5), if appropriate partially differently, to a predetermined dimension.
2. Method according to Claim 1, characterized in that, before the equalization of the wall thickness (S1), the cylindrical tubular portion (1a) is expanded on at least one end face, preferably on both end faces.
3. Method according to one of the preceding claims, characterized in that, during elongation, the flanks (6) are pressed with their end faces against an abutment (9a).
4. Method according to one of the preceding claims, characterized in that the precontouring of the flanks (6) and the equalization of their wall thickness (S1) take place by means of rolling.
5. Method according to one of the preceding claims, characterized in that the tolerance-induced excess material of the flanks (6) is utilized for a largely uniform thickening of the wall thickness (S3) of the deep bed (7).
6. Method according to one of the preceding claims, characterized in that the rim bed (1) is shaped into a final contour during the elongation of the flanks (6).
7. Method according to one of the preceding claims, characterized in that the free end regions of the flanks (6) are finish-machined, after their elongation, by means of forming rollers.
8. Device for carrying out the method according to Claim 1, characterized in that, for precontouring the rim bed (1) and equalizing the wall thickness of the flanks (6), an internal tool chuck (2) is provided, which has a first chuck part (3) and a second chuck part (4) which are moveable in the axial direction in relation to one another and the outer surface areas of which have a precontour (5), and in that a further internal tool chuck (2a) is provided, which consists of a first chuck part (3a) and of a second chuck part (4a) and which has on the surface area a contour (5a) corresponding to the contour of the finished rim bed (1) in the region of the flanks (6), and in that at least one pressure/rolling roller (8) is provided, by means of which the tubular portion (1a) can be pressed into the precontour (5) or the contour (5a).
9. Device according to Claim 8, characterized in that the precontour (5) is delimited by peripheral abutments (9) in the form of an edge.
10. Device according to either one of Claims 8 and 9, characterized in that the axially moveable chuck part (3) or (4) is moveable, spring-loaded, towards the other chuck part (3) or (4).
11. Device according to one of Claims 8-10, characterized in that the contour (5a) is delimited on each of the end faces by a peripheral abutment (9a).
12. Device according to one of Claims 8-11, characterized in that forming rollers (10) are provided by means of which the end regions of the contoured rim bed can be machined.

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