GB2315038A - Process and apparatus for the manufacture of film-coated moulded pieces - Google Patents

Abstract

The invention relates to a process for the reworking of molded pieces 2 made of thermoplastic material, which are coated over part of their surface with a film 6 and which have a margin 8 of the film 6 extending beyond the molded piece 2. Because cutting of the edge margin along the parting line can cause it to become detached or loosened, it is proposed according to the invention to laminate at least a portion of the film 6 margin against an as yet surface portion 12 of the molded piece. This is carried out in a reworking apparatus in which the film margin is folded by guide rolls, then if necessary is cut to a predetermined width in a cutting apparatus 30 then is pressed by pressure rolls 38 against the surface region 12 then together with the latter is warmed in a laminating apparatus 40, in order to weld the film margin to the surface region, whereupon the warmed region of the molded piece is again cooled in a cooling apparatus.

Description

Title: PROCESS AND APPARATUS FOR THE MANUFACTURE OF FILM-COATED MOLDED PIECES The invention relates to a process and apparatus for the manufacture or reworking of partly film-coated mold pieces having a film coating made of thermoplastic material.

Film-coated plastic parts are very widely used, in particular as plastic exterior members for the finishing of vehicles, for example as ornamental and protective strips for doors and other body components, bang strips or exterior mirrors, even for example as parts of furniture or cooking apparatus, as well as housings in the area of electronic communication, wherein thermoplastic materials like polyurethane find the greatest degree of use. Basically, film-coated thermoplastic molded parts can generally be used wherever a portion of a surface and in particular a visible surface is intended to have a colour which differs from the inherent colour of the molded part, or is intended to have a texture of which the negative cannot be (or only at great cost can be) directly provided on the surface of the mold half of a molding tool. Further uses for films on molded pieces made of thermoplastic material are found, for example, in the case where, because of a faulty mounting or lack of durability, or because of faulty varnishing apparatuses of the manufacturer, no colour application is possible.

Since subsequently applied films generally show inadequate adhesion, or can only be applied at substantially increased cost, it is preferable to apply the films during the manufacture of the molded pieces. To this end the film, prior to the manufacture of the molded piece, is positioned between the two mold halves of an open injection molding machine such that, for stability during closing of the mold around the mold cavity, the film edge is clamped and securely held in the separation plane between the mold halves. The film is so disposed that its coloured or textured surface is on the side facing away from the injection nozzle opening. Subsequently, the plastic is injected into the mold cavity, possibly with the injection of gas into the interior of the molded piece, such that the plastic comes into contact with the rearward face of the film, presses the film against the opposed wall of the mold cavity, and when hardened achieves an integral bond with the film.

After hardening, the mold is opened and the molded piece is removed.

Since the molded piece, in this condition, still has a gate, and since the film margin previously stretched between the mold halves projects beyond the molded piece, the molded piece after it has cooled and hardened still requires reworking before it is delivered or before undergoing further processing steps.

Previously, during reworking, the film margin has been removed, either by hand or by automatic cutting or by dies, along a line corresponding to the parting plane defined by the mold halves. In the design of the molded piece, the above-mentioned line is made to coincide with an edge which constitutes the outer edge of the exposed face of the molded piece. In such case, however, it can happen that the edge of the film separates slightly from the molded piece, which can have the result that, beginning at the outer edge of the visible surface, a large part of the film can separate, particularly with plastic external pieces for vehicles when exposed to adverse weather. In particular, when the cutting is carried out by hand, there is no guarantee that the cut will run straight and provide a clean edge.

It is an object of the present invention to obviate or mitigate the above disadvantages.

In general terms, the process aspect of the invention provides for the lamination of at least a portion of the film margin against an as yet uncoated surface region of the molded piece, the surface region being adjacent the already coated surface area. In this manner, in the preferred embodiment the marginal edge of the film extends from the outer edge of the visible surface of the molded piece to a non-visible location which is protected by the molded piece itself. This is particularly appropriate where the separation line between the coated and uncoated surface regions runs (as is common) along an edge which borders the visible surface of the molded piece.

In accordance with a preferred embodiment of the invention, the film margin encloses this separation edge of the molded piece, thus surrounding it, and is laminated to a surface area of the molded piece which lies adjacent the separation edge, preferably against the rear or back edge which is not visible. By this means, the marginal edge of the film is displaced away from the particularly exposed separation edge at the edge of the visible surface of the molded piece, thus improving particularly the adhesion and weatherresistance of plastic outer pieces for vehicles. When one is dealing with an edge-adjacent face which is a narrow face portion of the molded piece, for example an upper or lower end face of a bang strip with a C-shaped profile, it is advantageous for the film edge to wrap around the corresponding edge of the end face, so that its portion projecting beyond the end face runs essentially parallel with the film along a coated surface region adjacent the end face. The lamination of the film margin, i.e. the creation of an integral bond between the latter and the molded piece, occurs also in this case over the entire width of the wrapped film margin.

A further preferred embodiment of the invention provides that the film margin be welded without any previous application of a bonding or sticking agent on the molded piece. Basically, welding is ensured by using a temperature-stable film which, after warming the thermoplastic material of the molded piece, has its marginal portion pressed thereagainst. A preferred embodiment of the invention provides that, for the coating step, a film is used which is specially designed for the subsequent welding of its edge, and which includes at least one supporting layer which faces the molded piece and which melts or softens upon the application of heat, along with at least one temperature-stable covering or varnishing layer. While the support layer can be constituted by a thermoplastic material, heat-stable fluoropolymers are preferred for the covering layer.

Since the film margin projecting beyond the molded piece is relatively wide so as to ensure a stable grip between the mold halves during molding, the projecting film margin, according to a further advantageous embodiment of the invention, is cut prior to the lamination. This cut results in the film margin having a predetermined width matching the particular molded piece. It can also, in the edge region, be cut or die-cut at an angle to the direction of the edge of the molded piece, if it is not desired that the film margin be overlappingly laminated in this region. In the case of elongate, narrow molded pieces, the film edge can be entirely cut away at the narrow face, and laminated only at the elongate sides. The cutting of the film edge to a predetermined width is facilitated if the film edge, in accordance with a further advantageous embodiment of the invention, is bent or folded toward the uncoated surface region, preferably at about half the angle that is necessary to allow it to lie against the uncoated surface region.

In order to ensure uniformity and repeatability in the positioning of the molded piece during cutting and lamination of the film edge, the molded piece is preferably first deposited in a cavity in a support, the cavity shape conforming to the shape of the coated surface portion, so that at the edges of the molded piece, only the film margin extends beyond the cavity.

Finally, the part of the film margin adjacent the molded piece is pressed against the molded piece, and energy is provided thereto in order to weld it against the molded piece. A subsequent cooling step, while maintaining the pressure until complete hardening of the thermoplastic material of the molded piece or of the material of the support layer of the film, will ensure that the bond between the film margin and the molded piece will not loosen.

In the case where the film edge is to be laminated around two edges, for example in the region of a narrow forwardly directed surface, the lamination preferably takes place in two stages. Firstly, the part of the film margin adjacent the coated surface region is bent around the first edge and laminated against the forward face; subsequently, the remaining part of the film margin is pressed against an uncoated surface region adjacent the forward face, and then is provided with energy to bring about the welding.

In general terms, the apparatus for the reworking of partly film-coated molded pieces made of thermoplastic material and having projecting film margins, includes a device for laminating at least a part of the outwardly projecting film margin against an as yet uncoated surface region of the molded piece. In accordance with an advantageous embodiment of the invention, this laminating device includes at least one device for pressing and welding the film margin against the molded piece.

Ahead of the laminating device there is advantageously provided a further apparatus for cutting the film margin to a predetermined width, which advantageously includes one or more knives.

In order to ensure the uniform and repeatable positioning of the molded piece during both the cutting operation and the lamination of the film margin, a further preferred embodiment of the invention includes a molded piece support with a cavity in which the molded piece can be laid, the said support being movable relative to the laminating device and the cutting device. Basically, the laminating device and the cutting device can be fixed in position, while the molded piece support is moveable along guide rails, although the reverse can be more advantageous in the case of long pieces, due to space considerations.

The bending or folding of the film margin, which after the molding projects outwardly around the molded piece in essentially one plane, preferably takes place in two or more steps with the help of a guiding device for the film margin, the guiding device preferably including two or more sequentially arranged guide rolls. Advantageously, part of the guide roll arrangement is positioned ahead of the cutting device, and another part is positioned between the cutting device and the laminating device.

Advantageously, a cooling device is located behind the laminating device, in order quickly to cool the welded film margin. The cooling device can include a nozzle to which pressurized air is provided, the nozzle opening being directed toward the film margin. The cooling apparatus further includes, advantageously, one or more pressure rolls, which press the film margin against the molded piece until the welded bond is secure.

In order to permit a reworking of molded pieces with variable width or height, a further preferred embodiment of the invention provides that at least a portion, and preferably all, of the devices of the reworking apparatus which lie against the molded piece or the film margin, or are pressed thereagainst, or which grip the film margin, or elements of these devices, are adjustable perpendicular to the direction of movement with at least one degree of freedom, and preferably with two degrees of freedom.

A reworking of molded pieces which have curved edge surfaces in the direction of movement, can be made possible by ensuring that all devices of the reworking apparatus which lie against the molded piece or the film margin or are pressed thereagainst, or which grip the film margin, or components of these devices, are mounted for movement perpendicular to the movement direction with at least one degree of freedom and preferably with two degrees of freedom, and can be shifted, using a pressure device, until they abut against one or more abutment surfaces of the molded piece support being used. The pressure device can be constituted by compression springs, pneumatic drives or hydraulic drives.

An embodiment of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a simplified plan view of an apparatus for the reworking of partly film-coated molded pieces which are made of thermoplastic material and have an outwardly projecting film margin; Figure 2 is a side elevation of the apparatus according to Figure 1; Figure 3 is a sectional view taken along the line 3-3 in Figure 1, to a larger scale and in greater detail; Figure 4 is a detailed side elevation of the cutting device of the apparatus; Figure 5 is a section taken at the line 5-5 in Figure 1, to a larger scale; Figure 6 is a sectional view taken along the line 6-6 in Figure 1, to a larger scale; Figure 7 is a perspective view of a stationary molded piece support included in the apparatus; Figure 8 is a sectional view taken along the line 8-8 in Figure 7, with the molded piece lying in the support; and Figures 9-13 are complete or partially illustrated cross-sectional views of film-coated plastic external parts for vehicles.

The apparatus illustrated in Figures 1-8 serves to re-work injection molded pieces 2 made of thermoplastic material, which pieces, as seen in Figure 8, have been coated in a molding apparatus not illustrated over a part 4 of their surface with a film 6. In the apparatus, a substantially flat film margin 8, which after injection overhangs the molded piece 2, is bent around two opposed elongate side edges of the molded piece 2 at one of the molded piece edges 10 constituting the parting edges, and then is cut to a suitable width before it is caused, during a further bending step, to be pressed against an as yet uncoated surface region 12 of the molded piece 2. The region 12 is adjacent the edge 10 and the margin 8 is thereby laminated or welded against the region 12. The molded pieces 2 are secured in a stationary mounting support 14 for the reworking, and then a part of the apparatus, which is mounted for displacement with respect to the mounting support 14, is moved over the mounting support 14 in the direction of the arrow P (Figure 1), whereby the above-mentioned process steps can be taken one after the other.

The apparatus includes a stationary base plate 16 having an upper surface 18 to which the mounting support 14 is removably secured. Provided on the base plate 16 are two parallel cylindrical rails 20, spaced at equal distances above the upper surface 18. With the help of linear bearings 22, a carriage 24 is mounted on the rails 20 for back-and-forth movement in the longitudinal direction ofthe mounting support 14 (Figures 3 and 4). In the direction opposite the movement direction of the carriage 24 during the reworking of the molded piece 2 (arrow P in Figure 1), the carriage 24 supports, in sequence one after the other, two forward guide rolls 26 which bring the film margin 8 upright, a hold-down roll 28 to secure the molded piece in the mounting support 14 therefor, a cutting apparatus 30 for cutting the film margin 8, a further hold-down roll 34, two rearward guide rolls 36 for bending the film margin 8 adjacent the uncoated upper surface region 12, two pressure rolls 38 for pressing the film margin 8 against the upper surface region 12, a laminating or welding apparatus 40, and a cooling apparatus 42 (Figures 1 and 2), wherein these elements taken together constitute a re-working unit.

The length of the rails 20 is such that the carriage 24 can be displaced in both directions over the opposed end faces 44, 46 of the molded piece mounting support 14, in such a way that the complete reworking unit provided on the carriage 24 can reach a point where it is wholly beyond either of the ends 44, 46.

The molded piece mounting support 14, which is preferably made of aluminum, exhibits on its upper surface an upwardly open recess 48, the shape of which so matches the molded piece 2 that, during molding, the outer surface portion 4, covered with the film 6, lies flatly against the inside of the recess 48. The recess 48 is molded into an upper portion 50 of the mounting support 14, the portion 50, in contrast to the lower part 52 which is directed toward the base plate 16, not having a uniform width, but instead follow each of the lateral dimension of the molded piece 2. The upper edge of each of each of vertical side surfaces 54 continuously coincides with the lateral extremity of molded piece separating edges 10, which during molding are located at the parting line of the mold halves, so that the film margins 8 adjacent the separating edges 10 project outwardly beyond the recess 48 and can be easily worked (Figure 8).

Both the upper part 50 and the lower part 52 of the molded piece mounting support 14 have their respective end faces 44,46 extended beyond the ends of the recess 48.

For molded pieces 2 with a tapering rearward end, the rearward end 44 of the upper part 50 advantageously tapers to correspond to the taper of the molded piece 2, in order to facilitate the re-working of the upper surface of the recess 48. As an elongation of the upper part 50 of the molded piece mounting support 14, there is provided a plate 56 (Figure 7) which is mounted by screws on the lower part 52. The plate 56 has an end surface which corresponds with the taper of molded piece 2 and holds the rearward end of the molded piece 2 in the recess 48.

The securement of the molded piece mounting support 14 on the base plate 16 is accomplished with the help of a plurality of fastening bolts (not illustrated), which are distributed along the molded piece mounting support 14 and extend upwardly through the base plate 16 from underneath, and which further threadably engage in downwardly open threaded bores 60 of the molded piece mounting support 14 (Figure 8). Between the molded piece mounting support 14 and the base plate 16 there is provided a spacer plate 62 which has bores in the region of the securement bolts, and which has a width which corresponds to the width of the lower part 52 of the mounting support 14.

As can best be seen in Figure 3, components of the reworking unit, namely the guide rolls 26, cutting apparatus 30, rear guide rolls 36, pressure rolls 38, welding apparatus 40 and cooling roll 42 are mounted on a pair of vertical plates 25 that are slidably supported on a pair of rods 27. Springs 29 bias the plates 25 toward one another over the support 14. The forward guide rolls 26 are rotatably mounted about vertical rotation axes 64 and each has a cylindrical lower part 66 and an upwardly tapering frusto-conical upper part 68 which meets the lower part 66 and is integral therewith so that the outer diameter of the lower cylindrical part 66 corresponds to the maximum diameter of the misto-conical upper part 68 at the lower end thereof. The guide rolls 26 are mounted on support bolts 70 having an enlarged head and a cylindrical shaft 74 connected thereto, the shaft 74 projecting upwardly into a stepped bore 72 in the guide roll 26. An end shaft portion 76 with an external thread and a reduced diameter extends upwardly from each guide roll 26, and is threadably engaged in a downwardly open threaded bore 80 of a leading portion of the plates 25.

The springs 29 urge the plats 25 and the guide roll 26 inwardly in the direction of the molded piece mounting guide 14, until the guide roll 26 with its cylindrical lower part 66 comes into contact with one of the two vertical side surfaces 54 of the upper part 50 of the molded piece mounting support, which serve as abutment surfaces. The thickness of the spacer plate 62 is so selected that the peripheral edge between the lower cylindrical part 66 and the upper frusto-conical part 68 is located exactly at the same height as the separation edge 10 of the molded piece 2. By this provision, the projecting film margin 8 is bent at an angle upward around the separation edge 10, along a direction in which it is essentially perpendicular to the non-coated upper surface region 12 adjacent the separation edge 10, on the rearward side of the molded piece 2, so that it can be cut to a predetermined width with the help of the cutting device 30.

The cutting apparatus 30 consists essentially of two exchangeable knives 98, each being releasably secured to a knife holder 100 that is mounted on a respective one of the plates 25. The two adjacently arranged knife holders 100 include respectively two clamping jaws 102, 104, between which the knives 98 are held, so that their cutting edges are arranged essentially at mirror-image locations with respect to a midplane 106 of the apparatus over the molded piece mounting support 14. The cutting edges extend slopingly forward in the direction of the forward guide rolls 26 (Figure 4), such that they are essentially parallel to surface region 12 and therefore perpendicular to the upwardly obliquely bent film margin 8 (Figure 3). While the two lower clamping jaws 104 are rigidly connected to the knife holders 100, the two upper clamping jaws 102 are tightened against the respective lower clamping jaws 104 by way of an attachment bolt 106 which is tightened in order to securely clamp the knife 98.

The two knife holders 100 are vertically displaceable relative to the plates 25 so that the film strip 8 can be cut to a desired width. The vertical displacement of the knife holders 100 is accomplished with the help of a vertical adjusting screw 112 with an upper knurled head 114. The adjusting screw is supported in a bore 116 in an upper support member 118 on the plate 25 so as to be rotatable but not axially displaceable. The adjusting screw has, at its lower end, an external thread 122 which engages a corresponding internal thread in the lower end portion 120 of a vertical bore 124 of the knife holder 100. Around the adjusting screw 112 is a compression spring 126, which presses at its lower end against the knife holder 100 and with its upper end against the support member 118 thus eliminating play between the knife holder 100 and the adjusting screw 112.

In order to guide the knife holders 100, the plate 25 has vertical slots 130, each of which receives a correspondingly shaped guiding projection 132 of the knife holders 100. The two knife holders 100 are located by a pair of clamping screws 134, each of which is threadably engaged from the outside inward, through the vertical slot 130 in the adjacent plate 25.

In a manner similar to the forward guide rolls 26, the two rearward guide rolls 36 are likewise rotatably mounted about vertical rotational axes 146 on the plates 25 as seen in Figures 1 and 2. The guide rolls 36 are arranged such that their lower cylindrical part 152 rolls on the vertical side surfaces 54.

In contrast to the forward guide rolls 26, the upper part 150 of the rearward guide rolls 36 conically diverges upwardly from the cylindrical lower part 152, so that the film margin 8 on the opposed elongate edges of the mold part 2 is further bent toward the uncoated surface region 12 adjacent the parting edges 10 (Figures 1 and 2). The pressing rollers 38, located behind the rolls 36, are rotatably mounted on the plates 25, such that their rotational axes 156 (Figure 5) are angularly disposed corresponding to the slope of the upper surface region 12, and lie at such a spacing from the surface region 12 that the film edge 8 is pressed against the two elongate edges of the molded piece 2.

The laminating apparatus 40 is also carried by the plates 25 and consists essentially of two solid heating elements 158 which are located along the two elongate side edges of the molded piece 2. The heating elements 158 include internally positioned heating coils 160 (Fig. 6), but could alternatively be constructed as ultrasonic or laser welding elements. The rearward portion of the heating elements 158, in the direction of the cooling apparatus 42, has an undersurface or inner surface 162 conforming to the crosssectional shape of the molded piece 2 (Fig. 6). By contrast, a tapering guideway 166 is provided at the forward end of the heating element 158 between its lower face and inward face 162 and the surface region 12 of the molded piece or the side surface 54 of the mounting support 14, the tapering guideway contracting from the forward edge 164 of the heating elements 158 towards the rear. This tapering guideway 166 prevents the film margin 8 from becoming caught in the event that it projects somewhat in the upper or sideward direction.

The temperature within the heating elements 158 is selected such that the film edge 8 becomes, in the rearward part of the heating elements 158, welded against the surface region 12 which is adjacent the separating edges 10.

The cooling apparatus 42 located downstream of the heating elements 158 consists essentially oftwo further pressure rolls 168, which are in an arrangement similar to that for the pressure rolls 38. The pressure rolls 168 again press together, in warm condition, the film margin 8 and the surface region 12 adjacent the separating edges 10, after which two air nozzles 170 located downstream of the pressure rolls 168 for cooling purposes blow air against that portion of the film margin 8 which passes under the pressure rolls 168.

The carrier 24 includes a pair of vertical lateral members which carry a pair of opposed horizontal pivot bearings 140 for the axles 142 of the hold-down rolls 28 and 34. The hold down rolls 28,34 are provided respectively in front of and behind the knives 98 and the plates 25 have cut-outs 127,129 to allow independent lateral movement of the plates. The bearings 140 are located in slots 131 and biased downwardly by springs 133 to allow limited vertical movement of the rolls 28,34. The springs 133 acting on the axles 142 press the molded piece 2 into the cavity 48 of the molded piece mounting support 14.

In operation, therefore, the molded piece 2 is placed in the support 14 which has been mounted on the base plate 16. The carriage 24 is advanced across the piece 2 so that the leading rollers 26 flex the margins 8 upwardly into the path of the knives 98. The biasing of plates 25 carrying the rollers 26 allows the rollers and knives to follow the contours of the edge 10 and provide a smooth and accurate fold.

The rollers 28,34 engage the upwardly directed surface of the piece 2 to hold it in the support 14 as the knives sever the margins 8. The rollers 36 then continue the folding process to place the margin 8 in general alignment with the pressing rollers 38. The pressing rollers maintain the film margin 8 against the surface region 12 so that laminating apparatus 40 can weld the margin 8 to the surface region 12. The cooling rollers 168 maintain the pressure as the weld cools. After complete passage of the carriage 24 over the piece 2, it may then be returned and the piece 2 removed, or, alternatively, the piece 2 may be removed prior to retum of the carriage 24.

It will be appreciated that the carriage 24 may be advanced by any convenient means, for example hydraulic or pneumatic cylinders or a screw drive and that if preferred, the support 14 may be advanced and the processing equipment held stationery.

Similarly, the plates 25 may be biased toward one another by hydraulic, pneumatic or other resilient device to allow the reworking unit to follow the edge of the piece 2.

In order to facilitate the welding of the film margin 8 to the molded piece 2 made of thermoplastic material, it is possible to coat the molded piece 2, during injection molding, with films 6 incorporating a plurality of layers. The films 6 include at least one temperature-stable surface layer and a support layer which melts upon the application of heat and is provided on the face of the surface layer which is toward the molded piece. The characteristics of the surface layer and the support layer are so selected that the support layer becomes weak when at a temperature close to the melting point of the thermoplastic material, whereas the surface layer, at the same temperature, does not undergo any form alteration such as shrivelling or crinkling. What is attained thereby is that the film margin 8 can be bound flatly to the surface region 12 adjacent the separating edges 10 without damage to the material properties of the surface layer and without the danger of adhesion to the heating element 158.

While the surface layer consists preferably of one or more laminae of one or more different fluoropolymers, for example a coloured internal varnish layer and an extemal transparent varnish layer, the support layer is advantageously made of thermoplastic material, wherein the thermoplastic material of the support layer and that of the molded piece are the same, and thus have the same melting point.

Figures 9-13 show cross-sections through several re-worked molded pieces 2 of thermoplastic material used as trim strips or protective strips for automobiles, the molded pieces 2, during formation in an injection molding machine, having been coated with a film 6 on a part of its surface 4 serving as a visible surface, the projecting margin 8 being cut to a predetermined width in a subsequent re-working step, and, before and/or after the cutting, being laid or folded against an uncoated surface region 12 adjacently the separation edges 10, and laminated thereagainst by being welded onto the molded piece 2.

While the film margin 8, in the example embodiments illustrated in Figures 9 and 10, is bent only around the separatin two parts 9 and 13 separated by an edge 11. The additional folding, pressing and laminating may be performed with subsequent stages on the carriage 24 to replicate the steps of rollers 36,38 and laminating stage 40. Naturally, such additional rollers will be configured to follow the edge 11 and apply the requisite force and direction to the film 6.

The edges of the film margin 8 are thus located, in all embodiments, on the unseen back side of the molded piece 2, and are moreover, in the illustrated plastic outer parts of vehicles, protected against adverse weather.

Whereas the molded pieces 2 illustrated in Figures 9, 10 and 11 have an internal cavity 15, made by injecting gas inside the molded piece 2 during the injection molding procedure, the molded pieces illustrated in Figures 12 and 13 are manufactured without gas injection.

Claims (43)

1. A process for making molded pieces which are coated with a film over part

of their surface, said process comprising the steps of molding said piece with a film extending across a predetermined region of an outer surface of said piece with a margin of said film projecting from and unsecured to said region, and subsequently conforming said margin of said film to said outer surface of said piece and securing said margin to said outer surface in a location remote from said predetermined region.

2. A process according to claim 1 wherein said margins are trimmed prior to being conformed to said outer surface.

3. A process according to claim 1 in which said film is secured to said predetermined region during injection of molding material into a mold cavity to form said piece.

4. A process for re-working molded pieces which are coated on a part of their surface with an integrally bonded film during the formation of the molded piece, the edge of the film projecting beyond the molded piece, said process comprising the steps of bringing at least a part of the film margin into contact with an as yet uncoated surface region of the molded piece and laminating said film margin to said uncoated surface region.

5. A process according to claim 4 wherein said film margin is cut prior to being laminated to said piece.

6. A process according to claim 5 wherein said film margin is cut to a predetermined width.

7. A process according to claim 4 wherein said film margin is disposed adjacent an edge of said piece lying between the coated and the uncoated surface region and is laminated against said uncoated surface region adjacent to said edge in such a way as to enclose said edge.

8. A process according to one of claim 4 wherein said film margin is folded about said edge and said uncoated surface region is to be disposed against a surface to which said piece is to be attached, said margin thereby being secured and laminated to a normally unseen back side of the molded piece.

9. A process according to claim 7 wherein said film margin is folded around a second edge adjacent to said edge of the molded piece and is sequentially laminated to said uncoated surface region adjacent thereto.

10. A process according to claim 4 wherein lamination of said film margin includes welding it to the molded piece.

11. A process according to claim 5 wherein the film margin, before being cut, is folded in the direction of the coated surface region of the molded piece.

12. A process according to claim 11 wherein said film margin, after the cutting, is pressed against the uncoated surface region of the molded piece and warmed and welded to the molded piece.

13. A process according to claim 12 wherein said molded piece is cooled under pressure, at least in the region of the film margin welded thereto.

14. A process according to claim 4 wherein said molded piece is elongate and said film margin is laminated against two opposed longer-side edges of the molded piece, said film margin being severed at narrow face edges extending between said longer side edges.

15. A process according to claim 4 wherein said molded piece is disposed in a recess in a mounting support, the recess conforming to the film-covered surface.

16. A process according to claim 15 wherein said support has a periphery corresponding to the periphery of said piece and said periphery provides a guide to equipment used to contact and secure said margin with said piece.

17. An apparatus for the reworking of molded pieces having an integrally bonded film over a portion of their surface with the edge of the film projecting beyond the molded piece, said apparatus including a laminating apparatus for laminating at least one part of the projecting film margin against an as yet uncoated surface region of the molded piece.

18. An apparatus according to claim 17 wherein a cutting apparatus is provided in advance of said laminating apparatus for cutting said film margin to a predetermined width.

19. An apparatus according to claim 18 wherein a guide apparatus is provided for engaging and folding said film margin in the direction of said uncoated surface region.

20. An apparatus according to claim 19 wherein a guide apparatus is provided in front of and behind said cutting apparatus.

21. An apparatus according to claim 17 wherein said laminating apparatus includes a heating apparatus with at least one heating element.

22. An apparatus according to claim 17 wherein said laminating apparatus includes ultrasonic or laser welding elements.

23. An apparatus according to claim 21 wherein a cooling apparatus disposed behind the heating apparatus.

24. An apparatus according to claim 17 wherein at least one pressure roll disposed in advance of the laminating apparatus to maintain said piece in said support.

25. An apparatus of securing an edge of a film to a molded piece where said film is integrally bonded over a portion of the surface of said molded piece with said edge projecting beyond said molded piece, said apparatus including apparatus movable past said guide, said reworking apparatus including a guide apparatus for engaging and folding said film margin in the direction of an uncoated surface region, a cutting apparatus to trim said film margin to a predetermined width and a laminating apparatus for laminating said edge to said uncoated surface region.

26. An apparatus according to claim 25 wherein said reworking apparatus is movable in a direction normal to said support upon relative movement between said support and reworking apparatus to permit said reworking apparatus to follow a periphery of said piece.

2 7 . An apparatus according to claim 28 wherein said molded piece is retained on said support by a hold down apparatus located in advance of said cutting apparatus.

28. An apparatus according to claim 27 wherein said hold down apparatus is resiliently biased toward said support.

29. An apparatus according to claim 28 wherein said hold down apparatus includes a roller engageable with said molded piece.

30. An apparatus according to claim 29 wherein a second roller is provided to follow said cutting apparatus and hold said piece on said support.

31. An apparatus according to claim 26 wherein said guide apparatus includes a pair of rollers located on opposite sides of said cutting apparatus.

32. An apparatus according to claim 26 wherein said cutting apparatus includes a knife adjustable relative to said molded piece to vary said predetermined width of said margin.

33. An injection molded piece made of thermoplastic material which, when it is formed, is coated with an injected film covering part of its surface, a margin of said film over at least part of its length extends about and encloses an edge of said molded piece, said film being laminated to an uncoated surface region adjacent the edge.

34. An injection molded piece according to claim 33 wherein said film margin is welded to said surface region.

35. An injection molded piece according to claim 34 wherein said outward marginal edges of two laminated portions of opposing side edges of the molded piece lie essentially opposite one another.

36. An injection molded piece according to claim 34 wherein said film margin encloses two edges of a forward face of the molded pieces in which the portions of said film adjacent to said forward face extend essentially parallel with each other.

37. An injection molded piece according to claim 34 wherein said film includes at least one carrier layer directed toward said molded piece, said corner layer melting or becoming weak under the application of heat, and at least one surface film which remains stable under the application of heat.

38. A process according to claim 1 and substantially as hereinbefore described with reference to the accompanying drawings.

39. A process according to claim 4 and substantially as hereinbefore described with reference to the accompanying drawings.

40. Apparatus according to claim 17 and substantially as described herein with reference to and as shown in the accompanying drawings.

41. Apparatus according to claim 25 and substantially as described herein with reference to and as shown in the accompanying drawings.

42. An injection moulded piece according to claim 33 and substantially as shown in Figures 9 to 13 of the accompanying drawings.

43. Any novel feature or combination of features described herein.