Air spring

Abstract

The invention relates to an air spring having: a rolling bellows (1) with an opening which has a bead (2) reinforced by a core (3) and a rolling piston (4) with a seat (5) for the rolling bellows (1) and a support shoulder (7) for the rolling bellows (1),
wherein when the rolling bellows (1) is in the mounted state, its end assigned to the rolling piston (4) is connected to the rolling piston (4) in an airtight manner by a clamping fit between the bead (2) and the seat (5) of the rolling piston (4), and the bead (2) of the rolling bellows (1) rests at least partly on the support shoulder (7), wherein the rolling piston (4) is made of a thermoplastic material. The object of the invention is to improve an air spring of the type outlined above such that the bellows (1) can very reliably and simply be prevented from slipping off the piston (4), in particular in view of the use of plastic as the piston material. This is achieved in that on the seat (5) for the rolling bellows (1), the rolling piston (4) has an axially protruding, substantially cylindrical securing ring (8), which protrudes axially beyond the bead (2) of the rolling bellows (1) after mounting of the rolling bellows (1) on the seat (5), can be plasticized by an at least partial heating process, and in the plasticized state can be deformed radially outwardly over the bead (2) of the rolling bellows (1) by a forming die (9, 10, 11) such that the bead (2) is at least partly surrounded by the deformed securing ring (8).

Claims

1. An air spring, comprising: a rolling bellows with an opening which has a bead reinforced by a core; a rolling piston with a seat for the rolling bellows and a support shoulder for the rolling bellows; wherein when the rolling bellows is in a mounted state, its end assigned to the rolling piston is connected to the rolling piston in an airtight manner by a clamping fit between the bead and the seat of the rolling piston, and the bead of the rolling bellows rests at least partly on the support shoulder, wherein the rolling piston is made of a thermoplastic material; wherein on the seat for the rolling bellows, the rolling piston has an axially protruding, substantially cylindrical securing ring, which protrudes axially beyond the bead of the rolling bellows after mounting of the rolling bellows on the seat, can be plasticized by an at least partial heating process, and in a plasticized state can be deformed radially outward over the bead of the rolling bellows by means of a forming die such that the bead is at least partly surrounded by the deformed securing ring; the forming die includes a substantially conical region; and in the substantially conical region, the forming die has a forming region around the periphery which is curved concavely toward a radial outside, wherein a first small diameter of the forming region curved concavely toward the outside fits into the undeformed securing ring of the seat of the rolling piston.

2. The air spring as claimed in claim 1, wherein in the plasticized state, the securing ring can be deformed around the bead of the rolling bellows such that the bead can be pressed against the support shoulder of the rolling piston.

3. A method for production of an air spring, wherein the air spring comprises: a rolling bellows with an opening which has a bead reinforced by a core, and a rolling piston with a seat for the rolling bellows and a support shoulder for the rolling bellows, wherein the seat of the rolling piston has an axially protruding, substantially cylindrical securing ring, which, after mounting of the rolling bellows on the seat, protrudes axially beyond the bead of the rolling bellows, and the rolling piston is made of a thermoplastic material, wherein the method comprises: placing of the rolling bellows on the seat of the rolling piston; at least partial heating of the axially protruding securing ring of the rolling piston to the plasticization temperature of the plastic material of the rolling piston; insertion of a forming die in the securing ring of the seat of the rolling piston, wherein the forming die has at least one substantially conical region, the first small diameter of which fits in the seat of the rolling piston, and a second diameter of which is larger than the first diameter; axial pressing of the forming die into the securing ring of the rolling piston, wherein the conical region of the forming die shapes the seat of the rolling piston toward the radial outside; and removing of the forming die.

4. The method as claimed in claim 3, wherein in its substantially conical region, the forming die has a forming region around the periphery which is curved concavely toward the radial outside, wherein a first small diameter of the forming region curved concavely toward the outside fits into the undeformed securing ring of the seat of the rolling piston, wherein when the forming die is pressed in, the securing ring of the rolling piston is not only pressed toward the outside but also deformed around the bead of the rolling bellows following the curvature of the forming die.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) An example of the invention will be explained in more detail below on the basis of the drawing. The drawing shows:

(2) FIG. 1 in longitudinal section, a rolling bellows and a rolling piston in assembled state,

(3) FIG. 2 the assembled air spring with an inserted combined heating and forming die,

(4) FIG. 3 the combined heating and forming die further inserted, with the shaped seat of the rolling piston, and

(5) FIG. 4 a fully mounted air spring.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 shows a rolling bellows 1 with a bead 2. The bead 2 has an embedded to strengthening member 3 around its periphery. A rolling piston 4 has a partly conically shaped seat 5 with an inner diameter 6. A support shoulder 7 serves for better rolling of the rolling bellows 1 on the rolling piston 4 when the air spring is fully assembled. The seat 5 has a securing ring 8 axially adjoining the seat 5 and integrally connected to the seat 5. The bead 2 of the rolling bellows 1 is pushed onto the seat 5. The securing ring 8 protrudes beyond the bead 2 by a predefined extent.

(7) FIG. 2 shows a combined heating and forming die 9 inserted in the rolling bellows 1. The combined heating and forming die 9 has a heat radiator 10 and a forming tool 11. The forming tool 11 has a forming region 12 formed at least partially conical and curved concavely toward the radial outside. A first diameter 13 of the forming tool 11 corresponds to the inner diameter 6 of the seat 5. The securing ring 8 can be heated to plasticization temperature by the heat radiator 10.

(8) FIG. 3 shows the combined heating and forming die 9 inserted further into the seat 5 of the rolling piston 4. The securing ring 8 is here deformed by the deforming region 12, running around the periphery and curved concavely toward the radial outside, and engages over the bead 2 of the rolling bellows 1 corresponding to the contour of the forming region 12.

(9) FIG. 4 shows the finished connection of rolling bellows 1 and rolling piston 4. After cooling and associated hardening of the shaped securing ring 8, the rolling bellows 1 is inseparably connected to the rolling piston 4. The shaped securing ring 8 presses the bead 2 axially onto the rolling piston 4. This increases the security of the airtightness.

LIST OF REFERENCE SIGNS

Part of the Description

(10) 1 Rolling bellows 2 Bead of the rolling bellows 1 3 Core, strengthening member of the bead 2 4 Rolling piston 5 Seat of the rolling piston 4 6 Inner diameter of seat 5 7 Support shoulder of the rolling piston 4 8 Securing ring on seat 5 9 Combined heating and forming die 10 Heat radiator 11 Forming tool 12 Curved forming region of forming tool 11 13 First small diameter of forming tool 11