GB2279288A

GB2279288A - Method and apparatus for manufacturing an article

Info

Publication number: GB2279288A
Application number: GB9411817A
Authority: GB
Inventors: Georg Hummel
Original assignee: Dr Franz Schneider Kunststoffwerke GmbH and Co KG; Dr Franz Schneider GmbH
Current assignee: Dr Franz Schneider Kunststoffwerke GmbH and Co KG; Dr Franz Schneider GmbH
Priority date: 1993-06-15
Filing date: 1994-06-13
Publication date: 1995-01-04
Anticipated expiration: 2014-06-13
Also published as: ES2114766B1; DE4319751C1; GB2279288B; ES2114766A1; GB9411817D0

Description

2279288 Method for manufacturing an article and gpRaratus for oRerating

the method The invention concerns a method for manufacturing an article having a front side and a rear side, in particular a plastic article that is covered by a cover. The invention also relates to an apparatus for operating the method.

The article of the kind described above may be a latticed 10 loudspeaker cover, or any other shaped part as used in the motor vehicle or audio industries. The plastic article covered by the cover or shaped part may, moreover, be a product of the seating furniture industry or the like.

Hitherto loudspeaker covers have been manufactured by forming a cover of, for example, a fabric material, in such a way that the fabric material is at first introduced into a suitable mould and subsequently a synthetic material is injected into the mould. Because of the high pressures arising in this process. there occurs an impairment of the structure and a behaviour of the material which leads, in particular in the visual zone or the zone of use,, to an impairment because, on the one hand, the fabric is compressed on its surface and, on the other hand, there is a hardening of the fabric. All these effects must be considered to be detrimental.

The invention is therefore based on the problem of providing a method, and an apparatus for operating this method, whereby it becomes possible to cover an article with a cover in a simple and time-saving manner without any impairment of the structure and the material properties of the cover.

Accordingly one aspect of the present invention provides a method for manufacturing an article having a front side and a rear side, wherein the article is tightly covered at its front side with a cover which lies loosely against the article and the cover projects with an edge beyond the rear side of the article; and wherein subsequently a plastic body is injection moulded at the rear side of the article and is fixedly joined to the associated section of the projecting edge of the cover.

In this arrangement, it is possible to manufacture the article in a first mould and subsequently to introduce it into another suitable mould so as to provide it with the cover; however, it is advantageous if the article is manufactured in one mould wherein the article is, moreover, also covered with the cover. Because the fixing of the cover on the article is only effected by means of the plastic body formed at the rear side of the article, the advantage is derived that the cover lies loosely against the front side of the article,, but nevertheless the cover intimately covers the front side of the article. Thus, for example, any undesired formation of creases is avoided, and at the same time there is the advantage that neither the surface structure of the cover, nor its material property is modified. The material properties in question are to be understood to refer, in particular, to hardening of the cover material which, in 5 accordance with the invention, is avoided.

In carrying out the method in accordance with the invention, the plastic body fixing the cover edge may closely adhere to the rear side of the article as an independent part; it is, however, advantageous for the plastic body to be integrally joined to the plastic article. Thereby one obtains a mechanically rigid plastic article as a whole, with, at its front side, a cover which is tightly drawn over the front side. In such arrangement the original structure and the original material properties of the cover remain unchanged. If the front side of the plastic article has a convex spherical shape, the cover is accordingly applied to the front side of the article over a large area. However, it is, of course, also possible for the front side of the article to be concave or dished. In that case. the cover is either applied only to the article along a peripheral edge delimiting the front side, or it must be ensured that the cover is possibly also fixed point- wise to the dished or concave front side on the plastic article by means of a suitably formed plastic body. This is, in particular, possible if the plastic article is formed with appropriate cutouts. for example in the manner of a grid or lattice.

The plastic body injection moulded on the rear side may be in the form of a frame of the article. Such a frame-shaped plastic body only requires a comparatively small proportion of material for fixing the cover covering the front side of the article at the rear side of the article. Of course, the plastic body may be given any other desired shape depending on the shape of the article to be manufactured.

If a frame-shaped plastic body is used, it is expedient if it is injection-moulded at the peripheral edge of the rear side of the article, since in that case it is possible to fix the cover edge to the frame-shaped plastic body in a simple and reliable manner.

The method can be operated in a simple manner if a cover is used which has larger areal dimensions than those corresponding to the surface area or front side of the article, because mutual positioning of the article and cover then becomes more readily possible. In such a case, it has proved to be advantageous if the edge section of the cover freely projecting over the plastic body is cut off immediately after the plastic body has been injection moulded. This may be done in the same mould where the plastic body, fixing the section of the cover edge, is injection moulded at the rear side of the article.

In accordance with the invention, a permeable fabric material may be used as the cover. This is, for example, advantageous in loudspeaker covers because attenuations and distortion of the sound are thereby avoided as the sound passes through the article provided with a cover. In the upholstery industry an article manufactured in this way has the advantage that no lining need be used, so there is obtained an excellent seating ambience with the seating cushion or seating furniture in question.

If the article manufactured in accordance with the invention is used as a loudspeaker cover, it is expedient if, in a way known per se, the article is designed, at least sectionwise, in the manner of a lattice. Accordingly, it is possible to use as the cover a material structured in a lattice form.

In this arrangement, this may for example be a coarse-meshed fabric material.

A second aspect of the invention provides an apparatus for carrying out the above method including an injection mould which, for forming a first mould cavity corresponding to the plastic article and for forming a second mould cavity corresponding to the subsequently moulded plastic body. has a mould base part and f irst and second lid parts in an arrangement in which the first and second lid parts can be arranged successively on the mould base part; and including means for advancing a cover between the mould base part and the second lid part.

Thus an injection mould designed in such a way avails itself of the socalled multiple shot moulding principle, so as to obtain plastic articles loosely yet intimately covered by a cover within short production periods or cycles. it is expedient, for the same purpose, if the first and second lid parts are combined with each other and if they are designed to be adjustable with respect to the mould base part. This may, in this arrangement, be a rotary or sliding table mould or the like.

It has proved to be expedient, if the cover advancing means has a driver wind-on roller and a winding-off roller for a web-shaped cover, in which arrangement the winding-of f roller and the wind-on roller are arranged on the mould base part.

By means of such a cover advancing means it is readily possible to introduce on each occasion a suitable section of the cover between the base part of the mould and the second lid part (carrying the plastic body) so as to manufacture the plastic body covered by the cover.

It has,, moreover, proved expedient if the injection mould has a cuttingoff device which is provided for cutting off the remaining section of the cover edge which projects beyond the plastic body. This cutting-off device may be a cutting or stamping tool, or it may be a device by means of which the said remaining section of the cover edge is burned off from the plastic body.

In order that the present invention may more readily by understood the following description is given, merely by way of example, of individual steps of the method for manufacturing an article covered by a cover. and of the main parts of the apparatus in accordance with the invention for operating the method of the invention. In the drawings:-

Fig. 1 is a top plan view of a part of the injection mould for manufacturing an article covered by a cover; Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 is a section along the line B-B in Figure 1 is a section along the line A-A in Figure 1; is a diagrammatic representation of the next step of the method, following the step of Figure 3; is a diagrammatic representation of the next method step following the step of Figure 4; is a diagrammatic representation of the next method step following the step of Figure 5; is a sectional representation of the plastic article as obtained in the method step of Figure 3; Fig. 8 Fig. 9 Fig. 10 is a section through the plastic article which is loosely covered by a cover, that is to say the plastic article immediately after the method step of Figure 4. i.e. after the mould base part and the second lid part have been moved together; is a section through the plastic article once the cover shown in Figure 8 has been fixed by means of a plastic body formed on the rear side of the plastic article, i.e. this is a representation of the article as obtained in the method step of Figure 5; and is a section through the finished article after the cover edge projecting over the plastic body has been cut off, i.e. after the method step of Figure 6 has been executed.

Figure 1 shows an injection mould 10 with two mould compart- ments 12.

Figure 2 shows a section through the injection mould 10, wherein there are visible a mould base part 14 with a first lid part 16 and with a second lid part 18. The f irst lid part 16 and the second lid part 18 are combined with each other into one unit so as to obtain a rotary or sliding table mould.

In the closed state of the injection mould 10, a first mould cavity 20 is defined by means of the mould base part 14 and the first lid part 16. The first mould cavity 20 corresponds to the plastic article to be formed. A suitable synthetic material 22 is injected into the first mould cavity 20 and, after hardening, this forms the plastic article.

After production of the plastic article 24 which, as may be seen in Figure 1, has a grid-type or lattice-type shape, the injection mould 10 is opened as indicated by the double arrow 26 in Figure 3. Subsequently, the plastic article 24 is positioned, with a precise fit, on the second lid part 18 of the injection mould 10 with the plastic article 24 projecting laterally with its edge section 28 over a corresponding fitting projection 30 as may be seen in Figures 2 and 4; thus an undercut cavity 32 is obtained between the edge section 28 and the fitting projection 30.

in Figure 3 the injection mould 10 is illustrated with the mould base part 14 and the first lid part 16 in the closed state, so as to show the f irst mould cavity 20 with the synthetic material 22 having been injected therein so as to form the plastic body 24.

Figure 4 shows the production step where the injection mould 25 10 is open, in which the second lid part 18 with the plastic article 24 arranged on its fitting projection 30 has been withdrawn some distance away from the mould base part 14.

Moreover, Figure 4 shows a wind-up roller 34 and a windingoff roller 36 which are mounted on the mould base part 14.

A cover web 38 wound on the winding-off roller 36 can be moved step-wise past the mould base part 14 in the direction 5 of the arrow 40 by means of the driven wind-up roller 34.

Figure 5 shows a production step where the mould base part 14 is closed by the second lid part 18; in this step the plastic article 24 fills the mould cavity of the injection mould 10 with the exception of the undercut cavity 32. At the same time, in the position drawn in Figure 5, the cover 38 is tightly stretched round the front 42 of the plastic article 24 while adhering loosely thereto. A suitable synthetic material 44 is then injected into the undercut cavity 32 and fixedly joined to the associated section 46 of the projecting edge of the cover. This injected material may either closely bear on the rear 48 of the plastic article 24, or be integrally joined to the corresponding peripheral edge 50 of the plastic body 24. After the synthetic material 44 forming a plastic body 52 has hardened, the remaining section 54 of the cover 38, projecting freely over the plastic body 52. can be cut of f by means of a suitable tool 56 (viz. Figure 6).

In Figures 7 to 10, the individual steps of the method for manufacturing a plastic article are once more illustrated with reference to a loudspeaker cover,, where Figure 7 - 11 illustrates the plastic article 24 made of the synthetic material 22. The plastic article 24 has a grid-type or lattice-type shape; it has a front side 42 and a rear side 48, the peripheral edge section 28 being rounded off from the 5 front side 42 towards the rear side 48.

Figure 8 shows the plastic article 24 whose front side 42 is covered by a cover 38, in which arrangement the cover 38 is stretched with a remaining section (overhang) 54 covering the edge section 28 and projecting beyond the rear side 48 of the plastic article 24. The cover 38 covers the plastic article 24 by loosely bearing on the plastic article 24. Because of this, a modification of the structure or a modification of the properties of the material of the cover 38 is prevented.

Figure 9 shows the intermediate product according to Figure 8 but here the cover 38, which covers loosely yet intimately the front side 42 and the peripheral edge section 28 of the plastic article 24, is fixed on the plastic article 24 by means of the injection moulded plastic body 52. For this purpose, the plastic body 52, made of the synthetic material 44 is fixedly joined to the section 46 of the cover 38, or to the overhang edge section 54 of the cover 38, which immediately adjoins the edge section 28.

Figure 10 illustrates the finished article after the freely - 12 projecting overhang section 54 of the cover 38 has been cut off, the arrow 58 indicating the zone along which the cover 38 lies only loosely but intimately stretched against the plastic article 24, while the two small lateral arrows 60 are intended to indicate the zone along which the cover 38 is fixed to the plastic body 52; the plastic body 52 itself forms one unit with the plastic article 24.

Claims

A method for manufacturing an article having a front 5 side and a rear side, wherein the article is tightly covered at its front side with a cover which lies loosely against the article and the cover projects with an edge beyond the rear side of the article; and wherein subsequently a plastic body is injection moulded at the rear side of the article and is fixedly joined to the associated section of the projecting edge of the cover.
2. A method according to claim 1, wherein the plastic body is integrally joined to the plastic article.
3. A method according to claim 1 or 2, wherein said plastic body injection moulded at the rear side of the article is in the form of a frame of the article.
4. A method according to claim 3, wherein the frame-shaped plastic body is injection moulded on the peripheral edge of the rear side of the article.
5. A method according to any one of the preceding claims, wherein the section of the cover edge which projects over the plastic body is cut off immediately after the plastic body has been injection moulded.
6. A method according to any one of the preceding claims, wherein a permeable fabric material is used as the cover.
7. An apparatus for carrying out the method according to any one of the preceding claims, including an injection mould which, for forming a first mould cavity corresponding to the plastic article and for forming a second mould cavity corresponding to the subsequently moulded plastic body, has a mould base part and f irst and second lid parts in an arrangement in which the first and second lid parts can be arranged successively on the mould base part; and including means for advancing a cover between the mould base part and the second lid part.

is
8. An apparatus according to claim 7, wherein the first and second lid parts are combined with each other and are adjustable with respect to the mould base part.
9. An apparatus according to claim 7 or 8, wherein the cover advancing means has a wind-on roller and a winding-off roller for a web-shaped cover; and wherein the winding-off roller and the wind-on roller are arranged on the mould base part.
10. An apparatus according to any one of claims 7 to 9, wherein the injection mould has a cutting off device provided for cutting off a remaining section of the cover edge which - 15 projects over the plastic body moulded by said injection mould.
11. A method of manufacturing an article, substantially as hereinbefore described with reference to the accompanying drawings.
12. Apparatus for manufacturing an article, constructed and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.