EP2367669A1

EP2367669A1 - A method for the manufacture of products by injection moulding thermoplastic material to the face of a three- dimensional print

Info

Publication number: EP2367669A1
Application number: EP09833680A
Authority: EP
Inventors: Gunnar Bjørn LIE
Original assignee: AS OM BE Plast
Current assignee: AS OM BE Plast
Priority date: 2008-12-19
Filing date: 2009-12-15
Publication date: 2011-09-28
Also published as: NO331237B1; NO20085327L; WO2010071445A1; EP2367669A4

Abstract

A method for the manufacture of products using a basis component (1) in the form of a three-dimensional print created by means of additive fabrication or another machining comprises applying a layer of thermoplastic material (2) to at least one portion of a face of the basis component by injection moulding as to provide for a product having the same surface nature as the actual end product.

Description

A method for the manufacture of products by injection moulding thermoplastic material to the face of a three- dimensional print

The present invention relates to a method for the manufacture of products by layer moulding from material of thermoplastics or thermoplastic alloys such as ABS, poly- carbonate (PC)₅ nylon (PA), or the like. More particularly, the invention relates to layer moulding on physical three-dimensional basic components formed by means of additive fabrication, whereby there is provided a product having desired nature, in particular at the surface thereof. Thus, each basic component is a three-dimensional print from a printer of FDM, SLA, SLS, FDM, "epoxy", for instance, or another machined version.

Today, a problem of technologies for the manufacture of products based on such a three-dimensional print is that there is inter alia no possibility of achieving a correct surface, material, and colour of the print. Due to incorrect material quality of the surface, the product in the form of a print is not presenting the same visual impression as the "completed" product, for instance. Thus, as regards actual customers or users directly testing is impossible unless the product itself is physically manufactured using an expensive moulding tool. In lack of the required quality of the existing prints, the consequence is hence that substantial investments have to be made even for small series if, for instance, a product of plastics is to be tested in the market prior to start of the pro- duction. Then, should the testing prove that the product is not wanted, for instance, by the specific form thereof is considered unsuitable, the inevitable disadvantage is that the investment of the moulding tool is completely or at best partly wasted.

As indicated by the discussion above, there is an obvious need of more appropriate and inexpensive technical solutions for the manufacturing of smaller series with advanced plastic products also having a complex functionality. As there often is substantial doubt in connection with the reception as such by consumers, this involves considerable economical risks as regards the development of an expensive moulding tool for the production of series in restricted scale. Thus, the present invention is directed to remedy such an uncertainty by means of a substantial improvement of the nature of existing prints as mentioned above, whereby there is provided products at least having approximately the same surface nature as the end product. In other words, the products shall desirably have equal technical and functional properties like surface qualities of products made by conventional injection moulding technology, while minimizing the need expensive mould- ing tools for lower product series having demanding complexity. To comply with this need, there is according to the present invention proposed a method for the manufacture of products using a basis component in the form of a three-dimensional print created by means of additive fabrication or another machining, wherein applying a layer of thermoplastic material to at least one portion of a face of the basis component by injection moulding as to provide for a product having the same surface nature as the actual end product.

Preferred embodiments are specified by the dependent patent claims and the detailed discussion below.

Thereby, it is possible to form products by a combination of additive fabrication and injection moulding with structural, tolerance dependent, and aesthetical properties giving, as an example, the same visual impression as the end products for sale to the consuming parties. As a consequence, there is thus achieved a substantial reduction as to investments for moulding tools and, then, in particular when producing series in low scale.

Differently expressed, the advantages of the invention are:

1) Larger profitability for production volumes with additive fabrication.

2) Lower investments compared to conventional injection moulding in that the moulding tools may be simplified.

3) Shortened time prior to "the product is available in the market" compared to conventional injection moulding in that the moulding tools may be simplified. 4) improved structural properties for products basically formed by additive fabrication in that the moulded layer "improves" properties of the basis components.

5) Increased aesthetical properties for products provided by means of additive fabrication in that visual surfaces are formed by injection moulding.

6) Enhanced dimensional tolerances in that dimensional critical portions of the component are achieved by inj ection moulding.

For the sake of clarity, it is to be mentioned that:

1) Herein, injection moulding is defined as: Moulding plastic products in that liquid plastics, plastics in powdered form, plastics as pellet, or plastics in pasty form are injected into a moulding tool under pressure and harden or adhere by cooling, by supply of energy, or by setting. 2) Additive fabrication is derived from the English term "Additive fabrication" which according to Wohlers Report 2008 by Terry T. Wohler; Wohlers Associates, Inc. Fort Collins CO, USA is defined in this manner: "Additive fabrication refers to a group of technologies used for building physical models, prototypes, tooling components, and finished series production parts-all from 3D computer-aided design (CAD) data, CT or MRI scans, or data from 3D scanning systems. Unlike machining proc- esses, which are subtractive in nature, additive systems join together liquid, powder, or sheet materials to form objects. Parts that may be difficult or impossible to fabricate by any other method may be produced by additive fabrication. Based on thin horizontal cross sections take from a 3D computer model, they produce plastic, metal, ceramic or composite parts, layer upon layer."

Now, the invention is to be further discussed using preferred embodiments illustrated in the accompanying drawings, in which:

Fig. 1 a-c shows schematically a variant of a product illustrated in perspective, bottom and cross-section views, respectively, comprising a middle three-dimensional print externally and internally provided with a layer of suitable plastic material by means of injection moulding;

Fig. 2a-c shows schematically the same as Fig. la-c, except the injection moulded layer is only applied on an internal or external surface, respectively, of the three-dimensional print;

Fig. 3 a-c shows schematically the same as Fig. la-c, except the three-dimensional print is provided with a bushing or another type of insert,

Fig 4a-c shows schematically another variant of a large number of other possible products in top and to cross-section views, respectively; and

Fig. 5 shows schematically a cross-section view of a moulding tool for use when injection moulding of the product in Fig. 2b.

The unique by the principle according to the present invention for the manufacture of an actual product having desired configuration and material quality in the surface thereof, for instance, is that injection moulding is utilized for applying a layer 2 at least one portion of a face the basis component 1. The layer 2 may be made from any suitable thermoplastics or thermoplastic alloys as well. Thereby, the basis component 1 consti- tutes completely or partly a basis for the injection moulded layer 2 and forms along with this the end product. Moreover, the basis component 1 is preferentially provided in the form a three-dimensional print. As already mentioned above, the basis component 1 is created using additive fabrication. Prior to the injection moulding of the layer 2, the basis component 1 is preferentially located within a moulding tool for injection moulding, either by hand or using robots.

Thus, raw materials being part of the basis component and the injection moulded layer as well as determine technical properties of the product as regards strength, rigidness, surface-finish and size as well. The properties of the basis component itself are of importance to enable such a layer moulding which involves that it in particular relates to form stability, strength and rigidness thereof. The choice of moulding tool effects the size, configuration and complexity of the product. Another issue to be considered is how to possibly seal porous surfaces of the basis component and to bond the material used during injection moulding. It is also a presumption that bushings, inserts, or the like may be part of the product. An appropriate combination of materials for the injection moulded layer and the basis component effect the strength, adhesion, shrinkage, surfaces, tolerances, and deformations. For instance, it is of importance that the basis component may resist an injection pressure of up to 2500 kg/cm2 and a temperature until 400 ⁰C during the injection moulding.

The moulding tools may have a conventional construction or be based on product specific inserts situated within standard basic moulds. Referring to Fig. 5, it is as an example illustrated an appropriate moulding tool for use in connection with the present in- vention. Briefly, in this case the moulding tool consists of a inlet nozzle 5 ending in an insert 6 at an injection side of the tool. For mounting of the basis component 1, there is in addition at an outlet side of the tool an insert 7 having at least one associated ejector 8. However, it is nevertheless understood that any prior art moulding tool is applicable as well.

For instance, in addition to the configurations shown in the accompanying drawings, the basis component may be present in the form of a panel, cube, pyramid, sphere, combinations thereof, or any arbitrary configurations. Each basis component may be provided by means of any process of additive fabrication such as SLA, SLS, FDM, "epoxy", etc. Alternatively, the basis component may be provided by a machining of appropriate type. Moreover, the basis component may be formed of synthetic materials, minerals and combinations thereof and in addition wood. As illustrated in Fig. 1-4, the injection moulded layer may cover small, large or all faces of the basis component in any thickness. The injection moulded layer may be applied to the basis component in one or more moulding tools and operations. The moulded layer may also completely or partly fill open spaces between surfaces of or in connection with basis component. It is possible that the moulded layer may have any surface structure formed by rubbing, polishing, eroding, photo-etching, and the like. The moulded layer may have any colour or combination of desired colours. Moreover, it is possible the injection moulded layer may be utilized as a filling when large material thickness.

A moulded layer in the form of a injection moulded layer may be fastened to the basis component by adhesion, as an example in that the basis component is provided with glue prior to the injection moulding, in that the basis component is treated with other sorts of surface-treatment such as e.g. thermal treatment or any type of chemical struc- rural change, or in that the basis component is equipped with undercuts, holes, pockets, etc.

As shown in Fig. 3 and 4, when the moulded layer is applied, the basis component may be formed with other elements 4 such as bushings and inserts of metal or other materi- als. If so, these may be attached directly to the basis component, or alternatively using the injection moulded layer.

To improve the quality such as e.g. the properties of material, the final injection moulded product may be thermal treated in any suitable manner.

Claims

P a t e n t c l a i m s

1.

A method for the manufacture of products using a basis component (1) in the form of a 5 three-dimensional print created by means of additive fabrication or another machining, c h a r a c t e r i z e d i n applying a layer of thermoplastic material (2) to at least one portion of a face of the basis component by injection moulding as to provide for a product having the same surface nature as the actual end product. o

2.

A method according to the claim 1, c h a r a c t e r i z e d i n applying the layer (2) to the basis component within at least one moulding tool (3).

3. s A method according to any of the preceding claims, c h a r a c t e r i z e d i n forming completely or partly the layer (2) with a surface structure achieved by means of rubbing, polishing, eroding, photo-etching, and the like.

4. 0 A method according to any of the preceding claims, c h a r a c t e r i z e d i n forming the basis component (1) with at least one supplementary element (4) such as e.g. a bushing and insert.

5. S A method according to the claim 4, c h a r a c t e r i z e d i n directly fastening the at least one supplementary element in the basis component (1) or using the injection moulded layer (2).

6. 0 A method according to any of the preceding claims, c h a r a c t e r i z e d i n applying at least one colour to the layer (2).

7.

A method according to any of the preceding claims, c h a r a c t e r -S i z e d i n fastening the injection moulded layer (2) to the basis component by means of adhesion.

8.

A method according to the claim 7, c h a r a c t e r i z e d i n applying glue to the basis component (1) prior to the injection moulding.

9.

A method according to any of the preceding claims, c h a r a c t e r i z e d i n to enable secure attachment of the injection moulded layer (2), surface-treating the basis component (1) with a suitable thermal processing or chemical structural change, or formation of undercuts, holes, pockets, and the like.

10.

A method according to any of the preceding claims, c h a r a c t e r i z e d i n heat-treating the product in an appropriate manner after the injection moulding.