Method of producing a wheel of synthetics material

, The invention relates to a process for producing a plastic wheel of reinforced plastic, besthend from the rim, spokes and hub holder (EP-A-0 014 990).

In this known spoked both sides flat discs are mounted on a central portion. The one-piece middle part consists of ribbed, conical outwardly tapered spokes that connect the hub support and the rim, the latter being each provided between the spokes with an increasing until the middle in the height of rib. The central portion may be made in the injection molding process of reinforced plastic.

A more detailed statement of the type of injection-molding the central portion of a plastic wheel is missing. It must therefore be assumed according to the rules of the art, that this plastic part in the largest mass accumulation - is injected - namely to the hub holder. What has the disadvantage that the mass flows flow together in the rim, which is weakened at these points the material strength, especially that the rim is easily broken there with respect to shock.

The invention has for its object to provide a method for producing a plastic spoke wheel, which allows to fully utilize the material properties of the wheel under mechanical stress, in particular shock (curb) that the wheel imparts smooth running characteristics and having only a single operation ,

The object is inventively achieved in that the mass flows injected in at least two spokes and are guided so that they coalesce in the intermediate, arranged in an odd number on the rim spokes.

If the quotient of spokes by number of injection points is an even number, the flow lines will be specifying appropriate flow resistances in the spokes depending on the requirements in the top, middle, or foot area, so that the amplifier elements in the freely tensioned rim inevitably preferably tangentially are aligned in the circumferential direction. The optimum strength of the material can be used. This means that by avoiding the confluence of the mass flows in the rim, it can around the five to six times greater impact stress, as occurs, for example, when approaching a curb, take up.

The deflection of the amplifier elements in the region of the spokes makes strength moderately because of the presence at this point support through the spokes unnoticeable. The critical confluences of the mass flows are arranged in the region of the reinforcements as spoke or overflow. The plastic wheel is also distinguished by high concentricity, because a uniform over the entire circumference structure of the material is achieved by preferably aligned in the wheel peripheral amplifier elements, which may consist of mineral fiber. Of course, also this effect with polymers are obtained, which form a liquid crystalline melt.

Another advantage of the method is that the plastic wheel is completely finished in one operation.

On plastics to glass fiber-reinforced, thermoplastically processable polyamide molding compounds have proven particularly useful, which are composed of:<ul><li>A PA 6, PA 6.6, their copolymers or mixtures of polyamides having intrinsic viscosities of 2.5 to 3.5 dl / g, preferably 2.7-3.0 dl / g, measured in m-cresol,</li><li>B a Elastificator,</li><li>C a fibrous reinforcing agent.</li></ul>

Further show good results glass fiber-reinforced, thermoplastically processable polyester molding compositions which are composed of:<ul><li>A phase of a thermoplastic resin</li><li>B a Elastificator,</li><li>C a fibrous reinforcing agent.</li></ul>

The resin phase A is 75 to 100%, preferably to 80-95% of polyalkylene terephthalate and from 25 to 0%, preferably 20 to 5% of aromatic polycarbonate.

Among polyalkylene is understood PBTP or PETP, copolyesters based PBTP or PETP and mixtures of said polyesters in any mixing ratio with intrinsic viscosities of 0.60 to 1,20d! / G as measured in a solvent mixture of 50 parts of phenol and 50 parts of 1, 2-dichlorobenzene. Under aromatic polycarbonate is preferably understood as meaning a biphenol-A polycarbonate with intrinsic viscosities of 0.45 to 0.55 dl / g, measured in methylene chloride.

The aforementioned products are impact modified by means of suitable elastomers in an amount of 1 to 25%, preferably 5 to 20%, based on the mixture of A and B. By "suitable elastomers" impact-resistant modifiers are understood to be of as discrete particles having a particle size 0.1 to 0.6 pm, preferably 0.2 to 0.5 microns, dispersed in the resin phase A.

The products contain fibrous reinforcing agents, preferably mineral fibrous products such as glass fibers, with a L / D ratio of 10/1 to 50/1 in an amount of 10 to 50%, preferably 20 to 40% based on the total mixture of A + B + C.

Examples of the invention are illustrated in the drawings and are described in more detail below.

Show it: <ul><li>FIG. 1 view of a 8-spoke plastic wheel,</li><li>Fig. 2 cross-section through the rim,</li><li>FIG. 3 view of a wheel with resilient spokes.</li></ul>

<ul><li>In Fig. 1 a plastic wheel 1 represented with eight I-shaped spokes 2, which are connected in the middle with a hub mount 3 and the outside of the rim. 4 The injection points 5 are in the ratio: number of spokes 2 divided by number of injection points 5 arranged. This results in an even number. The confluence 6 of the mass flows in the range within the spoke 2, possibly in the not shown overflow.</li><li>In FIG. 2 is a cross section of the rim 4 is shown, wherein the rim flange 7 grows up to the center corresponding to the increase of the strength stress in the material thickness. In the plane of symmetry includes a molded ring 8 with reinforced foot 9 on, the latter significantly increased the moment of inertia.</li><li>In Fig. 3, the spoke 2, which connects the hub grip 3 and the rim 4, is bent, so that it yields resiliently in the case of load.</li></ul>