DE102022003424B4 - Method for manufacturing a ball stud assembly for a ball joint and method for manufacturing a ball joint - Google Patents

Abstract

Method for manufacturing a ball stud unit (1) for a ball joint (2), in particular for a suspension joint or guide joint, in particular for a vehicle, wherein a single-layer ball shell (3) made of plastic is injection molded onto a ball (4) of a ball stud (5) made of metal, and wherein, prior to manufacturing the ball shell (3), a surface structure (6) is produced at least section by section on the ball (4) of the ball stud (5) by means of a rolling tool (7).

Description

The invention relates to a method for manufacturing a ball stud unit for a ball joint and a method for manufacturing a ball joint.

From the state of the art, as in the DE 102 27 014 A1 A two-component bearing shell for an overmolded ball joint is described. The bearing shell has a core component made of a first material, which is completely enclosed by a shell component made of a second material.

In the DE 296 17 276 U1 A ball joint is described. The ball joint consists of a ball joint housing with molded-on fasteners, a ball of a ball stud pivotally mounted in a recess of the ball joint housing, and an elastic seal between the shaft and the ball joint housing. The seal consists of a molded covering made of a cross-linked and/or uncross-linked elastomer.

From the DE 1 575 550 A1 A bearing arrangement with a plastic running element is known. The bearing arrangement comprises a rigid, non-deformable housing having an opening bounded by a wall surface, an inner bearing element arranged within this opening, and a one-piece plastic running element located in the space between the inner bearing element and the wall surface bounding the housing opening. The inner bearing element has a minimal distance from the wall surface bounding the housing opening. The one-piece running element is made of a low-shrinkage plastic. This plastic is cast directly into the housing opening under relatively low pressure and, after casting, is in stress-free, rotationally permeable contact with the circumference of the inner bearing element and is in non-rotatable engagement with the wall surface bounding the housing opening.

In the DE 31 27 710 A1 A method for manufacturing a ball joint is described. The ball joint for use in motor vehicles consists of a joint pin with a one-piece molded ball head, a joint housing, and a sliding layer arranged between the ball head and the joint housing. In the method, the ball head is first coated with a lubricant. A lost form made of a synthetic material is then applied to the lubricant. The ball head is then centered in a mold for the joint housing, and finally, the free space between the ball head and the mold is filled with a synthetic material, which, in its solidified state, forms the joint housing.

From the EP 1 357 306 A1 A ball stud with an injection-molded plastic ball is known. The ball stud for a ball joint has a joint pin and a joint ball. The joint pin is made of a metallic material, and the joint ball, which is injection-molded onto the joint pin, is made of plastic.

In the JP 2000-81025 A A ball joint and its manufacturing process are described. The external threaded portion of a stud bolt is inserted into a mold for forming a ball head, and molten resin is injected into the mold. This assembly forms a ball head section using resin, into which an external screw section is cast, and a connecting bolt section consisting of the stud bolt protruding from the ball head section. The ball head section is then inserted into a mold for forming a body, and molten resin is injected into the mold. This assembly forms a ball-receiving chamber with a sliding surface that establishes sliding contact with the ball head section in a ball socket, while simultaneously forming the ball socket and a connecting rod in one piece.

From the DE 10 2007 009 322 A1 A metal ball joint for use in axially and/or radially loaded automotive suspension joints, consisting of a split joint housing and an integrated plastic bearing, and a method for its manufacture are known. The ball joint is designed as a hollow pin or as a solid pin and has a surface with increased roughness in the area of the ball joint or in the area of the ball and pin neck, produced by chemical, physical, and/or mechanical processing or by special profiling. This surface is form-fittingly encased with a thermoplastic polymer possessing high-quality tribological properties. The ball joint is first manufactured as a hollow pin or as a solid pin. Subsequently, the increased roughness in the area of the ball joint or in the area of the ball joint and pin neck is produced by chemical, physical, and/or mechanical processing or by special profiling, and then these areas are form-fittingly encased with plastic.

The invention is based on the objective of providing an improved method for manufacturing a ball stud unit for a ball joint compared to the prior art and a method that is superior to the prior art. to specify an improved method for manufacturing a ball joint.

The problem is solved according to the invention by a method for manufacturing a ball stud unit for a ball joint with the features of claim 1 and a method for manufacturing a ball joint with the features of claim 3.

Advantageous embodiments of the invention are the subject of the dependent claims.

In a method for manufacturing a ball stud assembly for a ball joint, a single-layer plastic ball shell is injection-molded onto a ball of a metal ball stud, according to the invention. The ball joint for which the ball stud assembly is intended is, in particular, a suspension joint or guide joint, especially for a vehicle. The ball shell is also referred to as a sliding shell.

The solution according to the invention produces a ball-and-socket assembly that achieves a fundamental reversal of the ball joint principle, since the ball socket is firmly connected to the ball of the ball stud, in particular by a material bond and/or a form-fit connection. In an inventive method for manufacturing a ball joint, in particular a suspension joint or guide joint, especially for a vehicle, it is therefore provided that a section of the ball-and-socket assembly, comprising the ball socket, is arranged in a ball joint housing, and the ball joint housing is closed with a sealing ring in which a seal is integrated. During joint movement of the ball joint, the ball socket, more precisely an outer surface of the ball socket, slides against the ball joint housing, more precisely an inner surface of the ball joint housing. The friction partners are thus the ball socket and the ball joint housing. In contrast, in the prior art, the ball socket is fixed in the housing, and the ball of the ball stud slides within the ball socket; that is, in the prior art, the ball of the ball stud slides against an inner surface of the ball socket. The friction partners here are therefore the ball of the ball stud and the ball socket. The solution according to the invention thus shifts a functional surface of the ball joint outwards.

The solution according to the invention does not require the ball to meet stringent shape and properties on the metallic ball stud. The directly injection-molded ball shell is easily measurable because it is rigidly connected to the ball stud. By shifting the functional surface of the ball joint outwards, a larger contact area is achieved, thus enabling better adjustment of friction tilting and friction torques.

The solution according to the invention reduces the number of components, since the spherical shell is already injection-molded onto the ball stud and therefore does not require assembly. Furthermore, the solution according to the invention reduces the requirements for the ball stud surface. As already mentioned, the injection-molded spherical shell is easily measurable, thus enabling effective process monitoring. The solution according to the invention also increases the total surface area of the friction partners, since friction takes place on the outer surface of the spherical shell.

• - der Kugelzapfen in einem zwei Formhälften einer Spritzform aufweisenden Spritzwerkzeug angeordnet und darin zentriert wird,
• - die erste Formhälfte in eine Verschlussposition bewegt wird,
• - die zweite Formhälfte in eine Verschlussposition bewegt wird, wodurch die Spritzform geschlossen wird, wobei die geschlossene Spritzform die Kugel des Kugelzapfens umschließt und zwischen der geschlossen Spritzform und der Kugel des Kugelzapfens eine Kavität zum Einspritzen des Kunststoffs ausgebildet wird,
• - die Kugelschale hergestellt wird, indem der Kunststoff in die Spritzform eingespritzt und an die Kugel des Kugelzapfens angespritzt wird, wobei der Kunststoff die Kavität ausfüllt, und
• - das Spritzwerkzeug geöffnet und die Kugelzapfeneinheit, aufweisend den Kugelzapfen mit daran angespritzter Kugelschale, entnommen wird.

The process for manufacturing the ball stud unit specifically provides that

• - the ball stud is arranged and centered in an injection mold comprising two mold halves,
• - the first half of the mold is moved into a closing position,
• - the second mold half is moved into a closing position, thereby closing the injection mold, with the closed injection mold enclosing the ball of the ball stud and a cavity for injecting the plastic being formed between the closed injection mold and the ball of the ball stud,
• - the spherical shell is produced by injecting the plastic into the injection mold and injecting it onto the sphere of the ball stud, with the plastic filling the cavity, and
• - the injection mold is opened and the ball stud unit, comprising the ball stud with the ball cup molded onto it, is removed.

According to the invention, prior to the production of the spherical shell, a surface structure is created at least partially on the sphere of the ball stud by means of a rolling tool.

Exemplary embodiments of the invention are explained in more detail below with reference to drawings.

• 1 schematisch einen Kugelzapfen,
• 2 schematisch ein Aufbringen einer Oberflächenstruktur auf eine Kugel des Kugelzapfens,
• 3 schematisch den Kugelzapfen mit einer Ausführungsform der Oberflächenstruktur,
• 4 schematisch den Kugelzapfen mit einer weiteren Ausführungsform der Oberflächenstruktur,
• 5 schematisch einen ersten Schritt zur Herstellung einer Kugelschale auf dem Kugelzapfen,
• 6 schematisch einen zweiten Schritt zur Herstellung der Kugelschale auf dem Kugelzapfen,
• 7 schematisch einen dritten Schritt zur Herstellung der Kugelschale auf dem Kugelzapfen,
• 8 schematisch einen vierten Schritt zur Herstellung der Kugelschale auf dem Kugelzapfen,
• 9 schematisch einen fünften Schritt zur Herstellung der Kugelschale auf dem Kugelzapfen,
• 10 schematisch eine Detailvergrößerung des Details X in 9,
• 11 schematisch eine Kugelzapfeneinheit,
• 12 schematisch eine Ausführungsform eines Kugelgelenks, und
• 13 schematisch eine weitere Ausführungsform eines Kugelgelenks.

This shows:

• 1 schematically a ball stud
• 2 schematically, an application of a surface structure to a ball of the ball stud,
• 3 schematically the ball stud with one embodiment of the surface structure,
• 4 schematically the ball stud with another embodiment of the surface structure,
• 5 schematically, a first step in the production of a spherical shell on the ball stud,
• 6 schematically a second step in the production of the spherical shell on the ball stud,
• 7 schematically a third step in the production of the spherical shell on the ball stud,
• 8 schematically a fourth step in the production of the spherical shell on the ball stud,
• 9 schematically a fifth step in the production of the spherical shell on the ball stud,
• 10 schematically a detailed enlargement of detail X in 9 ,
• 11 schematically a ball stud unit,
• 12 schematically a embodiment of a ball joint, and
• 13 schematically, another embodiment of a ball joint.

Corresponding parts are marked with the same reference symbols in all figures.

Based on the 1 to 13 The following describes a method for manufacturing a ball stud assembly 1 for a ball joint 2 and a method for manufacturing a ball joint 2. The ball joint 2 is, in particular, a suspension joint or guide joint, especially for a vehicle.

The process for manufacturing the ball stud unit 1 involves injection-molding a single-layer plastic spherical shell 3 onto a metal ball 4 of a ball stud 5. The spherical shell 3 is also referred to as a sliding shell.

First, the ball stud 5 is manufactured. In contrast to a conventional ball joint 2 design, there are no high requirements for the accuracy and surface quality of the ball 4. Advantageously, however, the surface of the ball 4 is provided to be rough and/or have various structures, for example a surface structure 6 similar to the surface of a golf ball, as in 2 right and in 3 shown, i.e., it has, for example, a plurality of spherical segment-shaped recesses. The surface structure 6 can, for example, be raised or recessed and/or evenly or unevenly distributed.

It is therefore optionally provided that a surface structure 6 is created, at least in sections, on the sphere 4 of the ball stud 5 before the spherical shell 3 is manufactured. This can be done, for example, using a rolling tool 7, as shown in 2 The ball 4 of the ball stud 5 and the rolling tool 7 are pressed against each other, as shown by the first arrows P1, and rotated in opposite directions, as shown by the second arrows P2. In the example shown, this results in the following: 2 right and in 3 Surface structure 6 shown, which resembles the surface of a golf ball.

4 shows another possible example of the surface structure 6 on the sphere 4 of the ball stud 5.

The 5 to 9 The figures show the production of the spherical shell 3, i.e., its injection molding onto the sphere 4 of the ball stud 5. The sphere 4 of the ball stud 5 is overmolded with plastic, for example polyoxymethylene (POM) or polyetheretherketone (PEEK), in an injection mold 8. In the illustrated example, the ball stud 5 is positioned and centered in the injection mold 8, which has two mold halves 9, 10, as shown in 5 shown. The injection tool 8 is also referred to as an injection mold and the injection mold as an injection mold.

The first half of the mold 9 is then moved into a closed position, as shown in 5 and 6 indicated by a third arrow P3. 6 The first half of the mold 9 is shown in the closed position.

The second mold half 10 is then moved into a closed position, as shown in 7 shown by means of a fourth arrow P4. 7 Figure 1 shows the second mold half 10 in the closed position. This closes the injection mold, whereby the closed injection mold encloses the ball 4 of the ball stud 5 and a cavity 11 for injecting the plastic is formed between the closed injection mold and the ball 4 of the ball stud 5.

The spherical shell 3 is then produced by injecting the plastic into the injection mold and injection molding it onto the sphere 4 of the ball stud 5, as shown in 8 by means of a fifth arrow P5 is shown. The plastic fills cavity 11.

The injection mold, i.e. its injection mold, is then opened and the ball stud unit 1, comprising the ball stud 5 with the ball shell 3 molded onto it, is removed. 9 This shows the finished ball stud unit 1, which was taken from the injection mold 8. 10 shows a detailed magnification of detail X in 9 , in particular a section of the spherical shell 3 applied to the sphere 4 of the ball stud 5.

This injection-molded spherical shell 3 is positively and/or materially bonded to the ball stud 5, more precisely to the sphere 4 of the ball stud 5. An outer surface of the spherical shell 3 is advantageously formed with high precision in terms of roundness and surface shape. It can, for example, form grease pockets 12, as in 11 shown, or exhibit other indentations. The injection mold is designed accordingly to create this structure on the outer surface of the spherical shell 3 during its manufacture.

The spherical shell 3 can, for example, have a variable wall thickness, i.e., different wall thicknesses in sections, and/or be reinforced with fibers, i.e., be made of a fiber-reinforced plastic. This is achieved, for example, by inserting or placing corresponding fibers into the injection mold and/or onto the ball 4 of the ball stud 5 before closing the mold, and/or by already mixing the plastic injected into the injection mold with corresponding fibers.

In the method for manufacturing the ball joint 2, a section of this ball stud unit 1, comprising the ball cup 3, is arranged in a ball joint housing 13, and the ball joint housing 13 is closed with a locking ring 14. 12 and 13 Two exemplary embodiments of such a ball joint 2 demonstrate this.

To make this possible, it is provided in particular that a spherical surface is produced in the ball joint housing 13, in particular by mechanical processing, especially while adhering to tight surface shape tolerances and small roughnesses, and also that a spherical surface is produced in the locking ring 14, in particular by mechanical processing, especially while adhering to tight surface shape tolerances and small roughnesses.

The ball stud assembly 1, in particular the section comprising the spherical socket 3, is then arranged in this ball joint housing 13 and fixed by means of the locking ring 14 that closes the ball joint housing 13. To enable this, the ball joint housing 13 and the locking ring 14 are designed such that a separation between the ball joint housing 13 and the locking ring 14 is provided precisely at the equator of the section of the ball stud assembly 1 with the spherical socket 3. This is a prerequisite for the ball joint 2 to be mounted according to this principle.

In one possible embodiment, illustrated in 13 Additionally, a seal 15 is integrated into the locking ring 14. To ensure tightness, the outer surface of the spherical shell 3 must not be exposed during installation. 11 The pivoting of the ball joint 2, as shown by the sixth arrow P6, does not cause it to lose contact with the seal 15. The position of the seal 15 is therefore matched to the size of the ball cup 3.

Reference symbol list

1

ball stud unit

2

ball joint

3

Spherical bowl

4

Bullet

5

ball stud

6

Surface structure

7

Rolling tool

8

injection mold

9

first half of the form

10

second half of the form

11

cavity

12

Fat pocket

13

Ball joint housing

14

Locking ring

15

seal

P1

first arrow

P2

second arrow

P3

third arrow

P4

fourth arrow

P5

fifth arrow

P6

sixth arrow

Claims (3)

Method for manufacturing a ball stud unit (1) for a ball joint (2), in particular for a suspension joint or guide joint, in particular for a vehicle, wherein a single-layer ball shell (3) made of plastic is injection molded onto a ball (4) of a ball stud (5) made of metal, and wherein, prior to manufacturing the ball shell (3), a surface structure (6) is produced at least section by section on the ball (4) of the ball stud (5) by means of a rolling tool (7). Procedure according to Claim 1 , characterized in that - the ball stud (5) is arranged and centered in an injection mold (8) having two mold halves (9, 10), - the first mold half (9) is moved into a closed position, - the second mold half (10) is moved into a closed position, thereby closing the injection mold, wherein the closed injection mold encloses the ball (4) of the ball stud (5) and a cavity (11) for injecting the plastic is formed between the closed injection mold and the ball (4) of the ball stud (5), - the spherical shell (3) is produced by injecting the plastic into the injection mold and injection molding it onto the ball (4) of the ball stud (5), wherein the plastic fills the cavity (11), and - the injection mold (8) is opened and the ball stud unit (1), comprising the ball stud (5) with the spherical shell (3) injection molded onto it, is removed. Method for manufacturing a ball joint (2), in particular a suspension joint or guide joint, especially for a vehicle, wherein a section having the ball shell (3) of a ball stud unit (1) manufactured by a method according to one of the preceding claims is arranged in a ball joint housing (13) and the ball joint housing (13) is closed with a locking ring (14) in which a seal (15) is integrated.