METHOD FOR MANUFACTURING A SEAT SHELL FOR A SEAT

Abstract

A method for manufacturing a seat shell for a chair includes three method steps (a) to (c). According to a first step (a), a carrier made of a plastic material is provided, on the front side of which a plastic film is arranged. According to a second step (b), the carrier with the plastic film is deep drawn by a deep drawing tool such that the front side of the carrier with the plastic film has a predefined three-dimensional surface contour after the deep drawing. According to a third step (c), a rear side of the carrier is encapsulated by injection molding with the plastic material.

Claims

1. A method for manufacturing a seat shell for a chair, the method comprising: (a) providing a carrier made of a plastic material and having a front side, and arranging a plastic film on the front side; (b) deep drawing the carrier with the plastic film by a deep drawing tool such that the front side of the carrier with the plastic film has a predefined, three-dimensional surface contour after the deep drawing; and (c) encapsulating by injection molding a rear side of the carrier with the plastic material.

2. The method according to claim 1, wherein the encapsulating by the injection molding in step (c) is carried out with a mono-sandwich method.

3. The method according to claim 2, further comprising: in the mono-sandwich method by which the rear side of the carrier is encapsulated by the injection molding with the plastic material in step (c), plasticizing a core component first in an injection unit of an injection tool, and subsequently dosing a skin component by a secondary extruder in a screw vestibule of the injection unit, and wherein materials located in a cylinder are not mixed but instead become deposited in the screw vestibule spatially one behind the other such that when an injection occurs, two materials inevitably flow in succession into a cavity such that the plastic component which flows in first is laid down as the skin component on the rear side of the carrier, and wherein a following plastic component forms a core of a shell body.

4. The method according to claim 2, further comprising: in the mono-sandwich method by which the rear side of the carrier is encapsulated by the injection molding with the plastic material in step (c), equipping an injection tool with a standard injection molding machine with a secondary extruder in a vertical or horizontal arrangement.

5. The method according to claim 2, further comprising: in the mono-sandwich method by which the rear side of the carrier is encapsulated by the injection molding with the plastic material in step (c), guiding a melt through a nozzle out of a secondary extruder and in front of a closed non-return valve of an injection unit, and pressing back the already plasticized plastic melt and a screw against an adjustable back pressure until a dosing path which has been set is achieved.

6. The method according to claim 1, further comprising: as a result of the encapsulating by the injection molding according to step (c), molding or forming on the rear side of the carrier a shell body which forms, together with the carrier and the plastic film, the seat shell for the chair, to which seat shell chair legs can be attached.

7. The method according to claim 1, further comprising: during the encapsulating by the injection molding according to step (c) injecting a plastic melt composed of the plastic material by an injection tool onto the rear side of the carrier such that the plastic melt fuses with the carrier.

8. The method according to claim 1, wherein the front side of the carrier which is provided in step (a), and which has the plastic film, has, after the deep drawing according to step (b), a curved three-dimensional surface contour at least in two directions which extend orthogonally with respect to one another.

9. The method according to claim 1, wherein the three-dimensional surface contour, predefined in step (b), of the front side of the carrier with the plastic film corresponds to the three-dimensional surface contour of a mold base which bounds a mold cavity in which the carrier with the plastic film is introduced to perform the encapsulating by the injection molding according to step (c).

10. The method according to claim 1, further comprising: making the plastic film, which is arranged on the front side of the carrier, to bear in a planar fashion on a mold base in order to perform the encapsulating by the injection molding according to step (c).

11. The method according claim 1, further comprising: securing during the encapsulating by the injection molding according to step (c) the plastic film electrostatically to a mold base.

12. The method according to claim 1, wherein a same plastic material or different plastic materials are used for the carrier and for the encapsulating of the carrier by the injection molding.

13. The method according to claim 1, wherein the plastic material for the carrier and/or for the encapsulating of the carrier by the injection molding is polypropylene.

14. The method according to claim 1, wherein the carrier, which is embodied in a planar fashion, has a carrier thickness between 0.3 mm and 0.7 mm.

15. The method according to claim 1, further comprising: performing the encapsulating by the injection molding according to step (c) such that a shell body which is molded on the carrier has a body thickness between 10 mm and 15 mm.

16. The seat shell for the chair, the seat shell comprising: the carrier made of the plastic material and having the front side; a plastic foil arranged on the front side; a shell body integrally molded onto the rear side of the carrier and being made of the plastic material, and wherein the seat shell is manufactured by the method according to claim 1.

17. The seat shell according to claim 16, wherein the front side of the carrier with the plastic film has a curved surface contour at least in two directions which extend orthogonally with respect to one another.

18. The seat shell according to claim 16, wherein the carrier and the shell body are made of a same plastic material or of different plastic materials.

19. The seat shell according to claim 16, wherein the carrier has a carrier thickness between 0.3 mm and 0.7 mm, and wherein the shell body has a body thickness between 10 mm and 15 mm.

20. The chair comprising: the seat shell according to claim 16 which forms a sitting surface and/or a backrest of the chair, and at least one chair leg attached to the seat shell.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The disclosure will now be described with reference to the drawings wherein:

[0033] FIG. 1 shows a highly simplified illustration of a carrier with a plastic film, which carrier is to be encapsulated by injection molding using the method according to the disclosure,

[0034] FIG. 2 shows a highly simplified illustration of an injection tool in which the encapsulation of the carrier with the plastic film is carried out by injection molding,

[0035] FIG. 3 shows an illustration showing the structure of the seat shell manufactured by the method, and

[0036] FIG. 4 shows an example of a chair using the seat shell according to the disclosure.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0037] Exemplary embodiments of the disclosure are illustrated in the drawings and are explained in more detail in the following detailed description, wherein identical reference symbols relate to identical or similar or functionally identical components.

[0038] The method according to an exemplary embodiment of the disclosure will be explained by way of example below with reference to FIG. 1. According to a first method step a) a carrier 1 composed of a plastic material K is made available. The carrier 1 which is formed in the planar or panel-like fashion and which has a carrier thickness t between 0.3 mm and 0.7 mm is expediently used. In the exemplary embodiment shown in the figures, the carrier thickness t is approximately 0.55 mm.

[0039] As shown in FIG. 1, a plastic film 2 is arranged on a front side 3 of the carrier 1. According to a second method step b), the carrier 1 including the plastic film 2 is deep drawn by a suitable deep drawing tool (not shown in FIG. 1 for the sake of clarity) in such a way that the front side 3 of the carrier 1 with the plastic film 2 has a predefined, three-dimensional surface contour 4a after the deep drawing.

[0040] FIG. 1 shows the carrier 1 with the plastic film 2 after the deep drawing in a sectional illustration. After the deep drawing, the front side 3 of the carrier 1 and therefore also the plastic film 2 have a curved surface contour 4a in two directions R1 and R2 which extend orthogonally with respect to one another. Since the direction R2 in the exemplary embodiments shown in the figures extends perpendicularly with respect to the plane of the drawing, the front-side curvature of the surface contour 4a of the carrier 1 with the plastic film 2 cannot be seen in this direction R2 in FIG. 1.

[0041] As shown in FIG. 2, the carrier 1 with the plastic film 2 is introduced, after the deep drawing, into an injection tool or injection molding tool 20 which has a mold cavity 5 for this purpose, in which mold cavity the carrier 1 with the plastic film 2 is arranged. The mold cavity 5 is bounded on the base side by a mold base 6. The three-dimensional surface contour 4a, predefined in step b), of the front side 3 of the carrier 1 with the plastic film 2 corresponds here to a three-dimensional surface contour 4b of the mold base 6 which bounds the mold cavity. The surface contour 4b of the mold base 6 and the surface contour 4a of the front side 3 of the carrier 1 are therefore matched to one another.

[0042] For the encapsulation by injection molding according to step c), the plastic film 2 which is arranged on the front side 3 of the carrier 1 and therefore also the carrier 1 itself are made to bear in a planar fashion on the mold base 6 of the mold cavity 5. Since the surface contours 4a and 4b of the mold base 6 and the carrier 1 are matched to one another, when the plastic film 2 is arranged on the mold base 6 an intermediate space is not formed between the plastic film 2 and the mold base. For the injection process which now follows, the plastic film 2 and therefore also the carrier 1 can be secured electrostatically to the mold base 6.

[0043] According to step c), a rear side 7 of the carrier lying opposite the front side 3 is encapsulated by injection molding by the injection tool 20, said carrier having a plastic material K. For this purpose, in a known fashion a plastic material K is injected from a nozzle 13 of the injection tool 20 into the mold cavity 5. Identical plastic materials K and K, that is to say K=K, are expediently used for the carrier 1 which is made available in step a) and for the encapsulation of the carrier 1 by injection molding according to step c). However, it is also conceivable to use different plastic materials K and K for the carrier 1 which is made available in step a) and for the encapsulation of the carrier 1 by injection molding according to step c). Polypropylene can expediently be used as the plastic material K and K for the carrier 1 and for the encapsulation of the carrier 1 by injection molding.

[0044] During the encapsulation by injection molding according to step c), a plastic melt 9 composed of the plastic material K is injected onto the rear side 7 of the carrier 1 by the injection tool 20, so that the plastic melt 9 fuses with the carrier 1. In this way, a shell body 8 is molded or formed on the rear side 7 of the carrier 1, which shell body 8 forms, together with the carrier 1 and the plastic film, a seat shell 12 for a chair 10 (not shown in FIG. 2).

[0045] In one variant, the encapsulation by injection molding can be carried out according to what is referred to as the mono-sandwich method in which the injection tool 20 is equipped with a standard injection molding machine with a secondary extruder in an optionally vertical or horizontal arrangement (not illustrated in more detail in FIG. 2). Firstly, the core component is plasticized in an injection unit 14 (indicated only in a rough schematic fashion in FIG. 2) of the injection tool 10. Subsequently, the secondary extruder doses the skin component into a screw vestibule of the injection unit. The melt flows through the nozzle 13 out of the secondary extruder in front of the closed non-return valve (not shown) of the injection unit 14 and the plastic melt, which is already plasticized, and the screw are pressed back against an adjustable back pressure until the set dosing path is achieved. In this context, the materials which are located in the cylinder are not mixed but instead are deposited spatially one behind the other in the screw vestibule. During the injection process, the two materials therefore flow inevitably in succession into the cavity, which results in the plastic component which flows in first being laid down as a skin component on the rear side 7 of the carrier 1, while the subsequent plastic component then forms the core of the shell body 8.

[0046] FIG. 3 illustrates the structure of a seat shell 12 which has been manufactured by the method according to an exemplary embodiment of the disclosure as explained above. Accordingly, the seat shell 12 includes the carrier 2 on the rear side 7 of which the shell body 8 is molded integrally. The seat shell 12 forms in the example in FIG. 3 both a seating surface 15 and a backrest 16 of a chair 10. According to FIG. 3, the plastic film 2 is arranged on the front side 3 of the carrier 1. For the sake of better illustration, in FIG. 3, the plastic film 2 is illustrated at a distance from the carrier 1. Of course, the plastic film 1 is placed in a planar fashion on the front side 3 of the carrier 1.

[0047] As is illustrated by FIG. 3, the carrier 1 with the plastic film 2 has a curved surface contour 4a in two directions R1 and R2 which extend orthogonally with respect to one another. The carrier 1 can have a carrier thickness between 0.3 mm and 0.7 mm, measured perpendicularly with respect to the sitting surface formed by the seat shell. In the exemplary embodiment shown in FIG. 3, the carrier thickness is 0.55 mm. The shell body 8 can have a body thickness k between 10 mm and 20 mm measured in the same direction as the carrier thickness t.

[0048] As shown in FIG. 4, chair legs 11 can be mounted on the seat shell 12 shown in FIG. 3, and in this way the chair 10 can be completed.

[0049] Further additional method steps for manufacturing the chair 10 are not necessary.

[0050] It is understood that the foregoing description is that of the exemplary embodiments of the disclosure and that various changes and modifications may be made thereto without departing from the spirit and scope of the disclosure as defined in the appended claims.