US-20260124812-A1 - METHOD FOR PRODUCING COMPOSITE PREFORMS

US20260124812A1US 20260124812 A1US20260124812 A1US 20260124812A1US-20260124812-A1

Abstract

The present invention relates to a method for producing composite preforms, in particular prosthesis composite preforms, which comprise fiber-reinforced plastics material, the method comprising a step of producing a multilayer laminate using a wet winding process which comprises forming a plurality of layers by winding at least one impregnated fiber onto a winding core; a step of detaching the laminate from the winding core; a step of reshaping the laminate such that the laminate has at least one predetermined curvature; and a step of consolidating the laminate in order to obtain a composite preform. The invention further relates to a method for producing composite preforms and to a composite preform.

Inventors

Daniel Kun

Assignees

steptics GmbH

Dates

Publication Date: 20260507
Application Date: 20230922
Priority Date: 20220929

Claims (15)

1 . Method for producing composite preforms in particular prosthesis composite preforms, which comprise fiber-reinforced plastics material, wherein the method comprises the following steps: producing a multilayer laminate using a wet winding process, wherein the wet winding process comprises forming a plurality of layers by winding at least one impregnated fiber onto a winding core; detaching the laminate from the winding core; reshaping the laminate such that the laminate has at least one predetermined curvature; and consolidating the laminate in order to obtain a composite preform.
2 . Method according to claim 1 , wherein a first layer of impregnated fiber wound onto the winding core contacts at least one second layer of impregnated fiber neighboring the first layer, over its entire extension.
3 . Method according to claim 1 , wherein a first layer of impregnated fiber is wound at a first specific angle relative to the winding core and a second layer of impregnated fiber is wound at a second specific angle relative to the winding core, which second angle deviates from the first specific angle, and wherein all the specific angles are between 0° and 90°.
4 . Method according to claim 1 , wherein the laminate is cut into a predetermined shape before the step of reshaping.
5 . Method according to claim 1 , wherein the laminate comprises at least one concave portion and at least one convex portion due to the reshaping.
6 . Method according to claim 1 , wherein the laminate is held by a receiving surface during the reshaping, and wherein the consolidation of the laminate is performed while the receiving surface holds the laminate.
7 . Method according to claim 1 , wherein the laminate is cooled for storage after the step of detaching from the winding core and before the step of reshaping, or after the step of reshaping and before the step of consolidation.
8 . Method according to claim 1 , wherein the step of consolidation is carried out at a pressure of 1 to 150 bar and at a temperature of 0 to 300° C. over a time period of 10 s to 30 min.
9 . Method according to claim 1 , wherein a thickness of the laminate after the step of detaching from the winding core is between 1 mm and 12 mm.
10 . Device for producing composite preforms in particular prosthesis composite preforms which comprise fiber-reinforced plastics material, wherein the device comprises: a fiber feed unit which is designed for guiding at least one fiber; a winding core which is of a substantially cylindrical shape; a winding unit which is designed for winding the fibers onto the winding core in a multilayer manner; a detachment unit which is designed for detaching a laminate, wound onto the winding core, from the winding core; a reshaping unit which is designed for reshaping the laminate, detached from the winding core, into a predetermined shape, and comprises a receiving surface for the laminate; and a consolidation unit which is designed for producing a composite preform by consolidating the laminate.
11 . Device according to claim 10 , wherein the winding unit is furthermore designed to wind a first layer of impregnated fiber onto the winding core in such a way that the first layer contacts at least one second layer of impregnated fiber neighboring the first layer, over its entire extension, and/or wherein the winding unit is furthermore designed to wind a first layer of impregnated fiber at a first specific angle relative to the winding core and to wind a second layer of impregnated fiber at a second specific angle relative to the winding core, which second angle deviates from the first specific angle, wherein all the specific angles are between 0° and 90°.
12 . Device according to claim 10 , wherein the detachment unit comprises cutting means which are designed for cutting the laminate into a predetermined shape.
13 . Device according to claim 10 , wherein the device comprises a cooling unit for cooling the laminate.
14 . Device according to claim 10 , wherein the receiving surface of the reshaping unit holds the laminate, and wherein the consolidation unit is designed for consolidating the laminate while the laminate is held on the receiving surface.
15 . Composite preform in particular prosthesis composite preform, produced according to a method according to claim 1 and by means of a device for producing the prosthesis composite preform, which comprise fiber-reinforced plastics material, wherein the device comprises: a fiber feed unit which is designed for guiding at least one fiber; a winding core which is of a substantially cylindrical shape; a winding unit which is designed for winding the fibers onto the winding core in a multilayer manner; a detachment unit which is designed for detaching a laminate, wound onto the winding core, from the winding core; a reshaping unit which is designed for reshaping the laminate, detached from the winding core, into a predetermined shape, and comprises a receiving surface for the laminate; and a consolidation unit which is designed for producing a composite preform by consolidating the laminate.

Description

DESCRIPTION The present invention relates to a method for producing composite preforms, in particular prosthesis composite preforms, which comprise fiber-reinforced plastics materials. The invention furthermore relates to a device for producing said composite preforms. Prostheses of all types, and in particular foot prostheses, have been continuously developed over recent years, in order to be able both to individually adjust them to the requirements of a patient in question and also to improve the performance and durability of the prostheses. Said prostheses must have a high degree of strength and resilience, while their own weight is advantageously as low as possible. This is made possible inter alia by carbon fiber reinforced plastics material (CRP), which has already long been used in the production of prostheses. CRP is a composite material which comprises carbon fibers embedded in a plastics matrix. In this case, the corresponding plastics matrix is routinely formed by epoxy resin. Prostheses preforms produced from CRP have a layered structure, in which a plurality of individual CRP or fiber layers is laid one on top of the other in a layered manner, until a desired material thickness is achieved. This production method is advantageous in particular because the material thickness of produced preforms can be flexibly adjusted in portions, and furthermore the arrangement and the orientation of individual fiber layers can also be influenced. This makes it possible in particular to set a desired strength and resilience of a prosthesis preform. Consequently, specific properties of a foot prosthesis, for example its energy intake, damping factor, bending, and energy output, which are of essential importance for movement sequences during walking, are already configured purposefully when producing the CRP preforms. Thus, for example EP 3 193 789 B 1 discloses a foot prosthesis of variable stiffness, the corresponding foot prosthesis comprising an elongate foot element and a heel element. The elongate foot element and the heel element are interconnected by screw connections and thus imitate the shape of a human foot. The rigidity and flexibility of the foot prosthesis is furthermore essentially determined by the interaction of the elongate foot element and the heel element. Since the requirements of a prosthesis with respect to its size and function may differ significantly depending on the patient, said prostheses are typically produced by hand. However, this is very time-consuming and costly. Accordingly, it is generally sought to simplify the manufacture of prostheses, such that in particular the preforms of a prosthesis consisting of CRP can be produced on an industrial scale. In this regard, DE 10 2014 213 294 B 4 discloses a method in which foot prosthesis composite preforms made of CRP can be produced by means of what is known as a wet winding method. For this purpose, in a first step a plurality of layers of at least one carbon fiber impregnated with epoxy resin is wound around a winding core or winding mandrel, in order to produce a multilayer laminate. Thereupon, the laminate consolidates on the winding core or can be consolidated in an accelerated manner by means of heat treatment, such that a cured, dimensionally stable material results, which has the shape of the winding core, i.e. is in particular cylindrical or oval. The process of consolidation involves curing the epoxy resin, as a result of which a solid plastics matrix composite material is produced, in which the carbon fiber is embedded. Subsequently, the consolidated laminate is released from the winding core and separated for further processing into a plurality of prosthesis composite preforms of predetermined shape. However, a disadvantage of the described production method is that the shape of the prosthesis composite preforms is specified by the winding core. In order to allow for efficient winding of the carbon fiber onto the winding core, the winding core must have a steady curvature, i.e. in particular be cylindrical or oval. Consequently, the consolidated laminate merely has a curvature identical to the winding core, as a result of which the shaping of the prosthesis composite preforms to be produced is greatly limited. In particular, in the case of some prostheses it may be necessary for there to be at least one change of curvature in portions. For example, a flexible heel portion of a foot prosthesis can comprise both a concave and a convex region. However, such prosthesis composite preforms cannot be produced by the method described above. The object of the present invention is therefore that of providing a method for producing composite preforms, in particular prosthesis composite preforms, which allows for particularly simple and time-efficient production of a plurality of composite preforms of variable shaping. A further object of the invention is that of providing a device which is designed for producing composite preforms ac