Method for fastening a plastic outer guide to a rolling bellows of an air spring by means of heating

Abstract

The invention relates to a method for fastening an outer guide (1) made of a plastic material to a rolling bellows (3) of an air spring (5) for a motor vehicle, said method comprising the following steps: - providing the rolling bellows (3), - providing a support ring (4) located within the rolling bellows (3), - providing the outer guide (1) located outside the rolling bellows (3), - wherein the outer guide (1) comprises a clamping region (2) by means of which the outer guide (1) is fastened to the rolling bellows (3), wherein the support ring (4) is positioned in a manner corresponding to the clamping region (2), - heating the clamping region (2) of the outer guide (1) by means of a heat source (8), - deforming the plastic material of the outer guide (1) in the heated clamping region (2) by means of a clamping tool (9) such that the outer guide (1) is pressed in a force-fitting manner against the support ring (4), wherein the heat source (8) heats the clamping region (2) by means of heat radiation.

Description

[0001] Method for attaching a plastic outer guide to a rolling bellows of an air spring by heating

[0002] The invention relates to a method for fastening a plastic outer guide to a rolling bellows of an air spring according to the preamble of claim 1 and to an air spring produced by the method.

[0003] Air springs or air struts, which are clamped between the chassis and the body of a motor vehicle and feature a rolling bellows, which in turn is secured between a cover and a rolling piston, are known in a wide variety of designs. During operation, the air spring is subjected to internal overpressure, and the rolling bellows rolls during spring movements, forming a rolling fold on the outer surface of the concentric rolling piston. To limit expansion, the rolling bellows is enclosed by a sleeve-shaped outer guide.

[0004] These air springs use external guides to limit the radial expansion of the bellows. The external guide also provides a rolling surface for the bellows' folds.

[0005] Such external guides are typically made of aluminum and are radially plastically reduced by means of externally acting clamping jaws and clamped onto a support located within the rolling bellows. In this way, the external guide is attached to the rolling bellows. Designs are also known in which the external guide is attached by means of a clamping ring located within the rolling bellows, which presses against the external guide from the inside. Furthermore, external guides made of a plastic material are also known. Such an external guide is known, for example, from DE 10 2019 209 491 A1.

[0006] From CN 202 646 505 U an air spring with an external guide is known, in which the external guide is deformed by means of a clamping tool acting on the outside and is thus pressed force-fittingly against a clamping ring positioned in the rolling bellows.

[0007] Furthermore, DE 19 95 281 U discloses attaching a protective sheath made of thermoplastic material to a retaining plate of a shock absorber by gripping the protective sheath with thermoelectric clamps, briefly heating the edge of the protective sheath surrounding the retaining plate, and pressing the plastic material into a circumferential groove in the retaining plate using the clamp pressure. After cooling, a circumferential constriction forms in the plastic material of the protective sheath, which is positively and force-fitted to the groove of the retaining plate, ensuring a tight clamp fit between the protective sheath and the retaining plate.

[0008] It is an object of the invention to provide a method for fastening an outer guide made of a plastic material to a rolling bellows of an air spring, the fastening type of which is improved in such a way that the fastening remains stable over a long operating period.

[0009] This object is achieved with the features of the method claim. Preferred embodiments can be found in the subclaims and in the following description of an embodiment with reference to the figures. They show:

[0010] Fig. 1 is a sectional view of an air spring, and

[0011] Fig. 2a to 2d show individual process steps for attaching a plastic outer guide to a rolling bellows.

[0012] Figure 1 shows a detail of an air spring 1 for a motor vehicle. Air spring 5 comprises an elastomeric rolling bellows 3, which is clamped pressure-tight between a cover 7 and a rolling piston 6. Rolling bellows 3 is partially enclosed by an externally adjacent outer guide 1. For fastening outer guide 1 to rolling bellows 3, a support ring 4 is provided within the outer guide, against which outer guide 1 is force-fitted in a clamping area 2. Outer guide 1 is made, for example, from a plastic material and is attached to rolling bellows 3 in the manner described below. Those skilled in the art will understand that the air spring and its components are essentially rotationally symmetrical bodies.

[0013] Figures 2a to 2d explain the individual process steps for the exemplary fastening of outer guide 1 to rolling bellows 3.

[0014] Figure 2a shows the rolling bellows 3, the support ring 4 positioned inside the rolling bellows 3, and the outer guide 1 positioned outside the rolling bellows 3 prior to their joint connection. The outer guide 1 comprises a clamping area 2, which is provided for the frictional fastening of the outer guide 1 to the rolling bellows 3 by means of a support ring 4. This clamping area 2 is thermally warmed / heated by means of a heat source. The heat is emitted by a heat source 8 towards the clamping area 2, causing it to warm / heat. Depending on the heat source 8 used, the heat is transferred to the outer guide 1 by thermal radiation, thermal conduction, or convection. The heating takes place until the material used is plastically deformable. The temperature required for plastic deformation in the clamping area 2 depends on the plastic material used.

[0015] After heating up to the point of plastic deformation of clamping area 2, the outer guide 1 is pressed by means of a clamping tool 9 as shown in Figure 2b. Clamping tool 9 engages the outside of outer guide 1 and deforms the heated clamping area 2 against rolling bellows 3 or support ring 4.

[0016] For example, clamping tool 9 is used as the heat source. For this purpose, clamping tool 9 is tempered, and when it rests directly against outer guide 1, clamping area 2 is heated by heat conduction until it undergoes plastic deformation. To accelerate cooling, a cooling source 10 is used, for example, as illustrated in Figure 2c. During pressing using clamping tool 9, a cooling source 10 acts on clamping area 2 and clamping tool 9. This accelerates the cooling or curing of the plastic material of outer guide 1. After outer guide 1 has cooled, clamping tool 9 is finally retracted as shown in Figure 2d, and outer guide 1 is firmly attached to the rolling bellows 3 by means of support 4.

[0017] List of reference symbols

[0018] 1 outdoor tour

[0019] 2 Clamping area 3 Bellows

[0020] 4 support ring

[0021] 5 air spring

[0022] 6 rolling pistons

[0023] 7 Lid 8 Heat source

[0024] 9 clamping tool

[0025] 10 Cooling source

Claims

Patent claims 1 . A method for attaching an outer guide (1) made of a plastic material to a rolling bellows (3) of an air spring (5) for a motor vehicle, comprising the following steps: Providing the rolling bellows (3), Providing a support ring (4) located inside the rolling bellows (3), providing the outer guide (1) located outside the rolling bellows (3), wherein the outer guide (1) comprises a clamping area (2) by means of which the outer guide (1) is fastened to the rolling bellows (3), wherein the support ring (4) is positioned corresponding to the clamping area (2), characterized by, Heating the clamping area (2) of the outer guide (1) by means of a heat source (8), Deforming the plastic material of the outer guide (1) in the heated clamping area (2) by means of a clamping tool (9) so that the outer guide (1) is pressed force-fittingly against the support ring (4), wherein the heat source (8) heats the clamping area (2) by means of thermal radiation.

2. Method according to claim 1, characterized in that the plastic material of the outer guide (1) is heated to its material-specific plastic deformability.

3. Method according to claim 1 or 2, characterized in that after the deformation of the plastic material of the outer guide (1) by the clamping tool (9), a cooling source acts on the clamping area (2) in a cooling manner.

4. Air spring for a motor vehicle, comprising a rolling bellows (3) which is clamped pressure-tight between a rolling piston (6) and a cover (7) and is surrounded by an outer guide (1), wherein the outer guide was fastened to the rolling bellows (3) by the method according to claim 1.

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