OUTER SHELL FOR A DISPENSER AND METHOD FOR PRODUCING SUCH AN OUTER SHELL

Abstract

An outer shell for a dispenser and a method for making same are provided, the outer shell including first and second injection molded plastic component parts. The first and second component parts each include an outer surface and an inner surface, with the first component part having a first mating surface directed to the outer surface of the first component part and the second component part having a second mating surface directed to an inner surface of the second component part. The first and second component parts are joined to each other along a seam by mating the first mating surface and the second mating surface during injection moulding. A plurality of recesses is formed in the inner surface of the first component part along the seam and/or on a gate protrusion extending away from a free end of the first mating surface of the first component part.

Claims

1. Outer shell for a dispenser, the outer shell comprising: a first injection moulded plastic component part (17; 41a) and a second injection moulded plastic component part (18; 42a); wherein the first and second component parts each comprise an outer surface (2) and an inner surface (1), wherein the first component part has a first mating surface (43a) directed to the outer surface of the first component part and the second component part has a second mating surface directed to an inner surface of the second component part, wherein the first and second component parts are joined to each other along a seam (21) by mating said first mating surface and said second mating surface during injection moulding, wherein a plurality of recesses (49; 50) is formed in the inner surface of the first component part along at least a part of the seam and/or on a gate protrusion (24) extending away from a free end of the first mating surface of the first component part.

2. Outer shell according to claim 1, wherein the recesses (49; 50) are provided with an undercut.

3. Outer shell according to claim 2, wherein an undercut angle resides between 3° and 20°, preferably 5° to 15° and most preferably 8° to 13°.

4. Outer shell according to any one of the preceding claims, wherein the recesses (49; 50) are arranged in a row.

5. Outer shell according to claim 4, wherein the depth of the recesses (49; 50) is lowest at opposite ends of the row and highest in a center between the opposite ends.

6. Outer shell according to any one of the preceding claims, wherein the recesses (49; 50) have a rectangularly shaped top view, particularly a square shaped top view, or a circularly or ovally shaped top view.

7. Outer shell according to claim 6, wherein one edge of the rectangle extends parallel to the free end of the first mating surface and/or a free end of the gate protrusion.

8. Outer shell according to any one of the preceding claims, wherein the recesses (49; 50) extend along the entire length of the seam.

9. Outer shell according to any one of the preceding claims, wherein the outer surfaces (2) and/or inner surfaces (1) of the first and second component parts are flush along the seam.

10. Outer shell according to any one of the preceding claims, wherein said first mating surface and said second mating surface are generally non-planar.

11. Outer shell according to any one of the preceding claims, wherein said first component part (17; 41a) is made of MABS and said second component part is made of ABS.

12. Outer shell according to claim 11, wherein said second component part (18; 42a) is an opaque ABS plastic material.

13. Outer shell according to claim 11 or 12, wherein said first component part (17; 41a) is a transparent MABS plastic material.

14. Outer shell according to any one of the preceding claims, wherein the first and second component parts (17, 18; 41a, 42a) each further comprise a first side surface and a second side surface, wherein the first and second side surfaces each have a free edge (22, 23; 81, 82) facing away from the outer surface (2) and wherein the seam (21) extends from the free edges of the first side surfaces to the free edges of the second side surfaces.

15. Method of manufacturing an outer shell of a dispenser part, the method comprising: performing a first injection moulding step to produce a first component part (17; 41a) of the outer shell in a mould, wherein the first component part comprises a outer surface (2) and an inner surface (1), wherein the first component part has a first mating surface (43a) directed to the outer surface of the first component part; retaining the first component part in the mould and engaging a plurality of protrusions (49′; 50′) provided on a surface of the mould (19) with the first component part during the first injection moulding step, the protrusions being provided on a surface of the mould corresponding to the inner surface of the first component part and along at least a part of an inner end (44) of the first mating surface (43a) of the first component part and/or on a gate protrusion (24) extending away from a free end (44) of the first mating surface of the first component part; and performing a second injection moulding step to produce a second component part (18; 42a) in the mould (19), wherein the second component part comprises a outer surface (2) and an inner surface (1), wherein the second component part has a second mating surface directed to an inner surface of the second component part, wherein the first and second component parts are joined to each other along a seam (21) by mating said first mating surface (43a) and said second mating surface during the second injection moulding step.

16. Method according to claim 15, wherein the protrusions (49′; 50′) are provided with an undercut.

17. Method according to claim 16, wherein an undercut angle resides between 3° and 20°, preferably 5° to 15° and most preferably 8° to 13°.

18. Method according to any one of claims 15 to 17, wherein the protrusions (49′; 50′) are arranged in a row.

19. Method according to claim 18, wherein the height of the protrusions (49′; 50′) is lowest at opposite ends of the row and highest in a center between the opposite ends.

20. Method according to any one of claims 15 to 19, wherein the protrusions (49′; 50′) have a rectangularly shaped top view, particularly a square shaped top view, or a circularly shaped or ovally shaped top view.

21. Method according to claim 20, wherein one edge of the rectangle extends parallel to the free end of the first mating surface and/or a free end of the gate protrusion.

22. Method according to any one of claims 15 to 21, wherein the mould (19) is moved, particularly rotated, from a first cavity (15) to a second cavity (16) between the first injection moulding step and the second injection moulding step while retaining the first component part (17; 41a) in the mould (19).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Various additional features and advantages of the invention will become more apparent to those of ordinary skill in the art upon review of the following detailed description of one or more illustrative embodiments taken in conjunction with the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the general description given above and the detailed description given below, explain the one or more embodiments of the invention.

[0045] FIG. 1A is a schematic top view of an arrangement for carrying out a molding process for making an outer shell according to the invention, with a mould in a first position.

[0046] FIG. 1B is a schematic top view of the arrangement of FIG. 1A, with the mould in a second position.

[0047] FIG. 2 is a perspective view of an outer shell made by the process according to the disclosure.

[0048] FIG. 3 is a cross-sectional view of a prior art seam.

[0049] FIG. 4 is a cross-sectional view of a cross-section through a seam according to the disclosure.

[0050] FIG. 5 is an enlarged view of the seam of FIG. 4.

[0051] FIG. 6 is a perspective view of a first outer shell provided with multiple steps.

[0052] FIG. 7 is a partial top perspective view of the mould.

[0053] FIG. 8 is an enlarged detail perspective view of the mould of FIG. 7 corresponding to the detail rectangle shown in FIG. 7.

[0054] FIG. 9 is a partial perspective exploded view towards the inner surface of an outer shell.

[0055] FIG. 10 is a top perspective view of an outer shell provided with a stepped edge as shown in FIG. 6.

[0056] FIG. 11 is a cross-sectional view through another seam.

[0057] FIG. 12 is a perspective view of a dispenser comprising an outer shell according to one embodiment of the invention.

[0058] FIG. 13 is a perspective view of a dispenser comprising an outer shell according to another embodiment of the invention.

[0059] FIG. 14 is a perspective view of a dispenser comprising an outer shell according to the disclosure.

EMBODIMENTS OF THE DISCLOSURE

[0060] FIGS. 1A and 1B show a schematic illustration of an arrangement for carrying out a two component injection molding process for making an outer shell according to embodiments of this invention.

[0061] In this example, the process uses two injection units 11, 12 and a rotary mould M designed for sequential injection of a single part using two different materials. In the subsequent text, the process is described for the injection of a transparent and an opaque material, but it is applicable for any combination of transparent and/or colored materials. The mould M used in this example is a two cavity mould. The mould M is held closed in a first cavity position shown in FIG. 1A and heated to a predetermined operating temperature. The first material, which is usually the material having the highest injection temperature, is injected from the first injection unit 11 through a primary runner system 13 into a first cavity 15 to form a first component part 17. In this example, the first material is a transparent or translucent resin. During the first injection, the mould volume to be occupied by the second material is shut off from the primary runner system. The mould is opened and a core plate 19 (mould) is rotated 180°, as indicated by the arrow A, into a second cavity position shown in FIG. 1B, where after the mould closes. A secondary runner system 14 is connected to the volume to be filled and the second material is injected from the second injection unit 12 into a second cavity 16 to form a second component part 18. In this example, the second material is an opaque resin. After sufficient cooling of the injected outer shell 17, 18, the mould is opened and the outer shell is ejected.

[0062] The tool design used in the described example is a rotating core plate. This comprises a two-station tool that rotates in a vertical (or horizontal) direction. The rotating plate is held in a first position at a first injection station for the injection of the first material. It is then rotated into a second position at a second injection station for the injection of the second material.

[0063] An alternative tool design is a core back. In a core back, a sliding core is first closed and the first material is injected. The sliding core is then opened and the second material is injected.

[0064] A portion of the core plate or back (also referred to as the mould) 19 is shown in more detail in FIGS. 7 and 8. The mould 19 comprises an outer surface divided into a first outer surface 17′ corresponding to the inner surface of the first component part 17 and a second outer surface 18′ corresponding to the inner surface of the second component part 18.

[0065] FIG. 2 shows a schematic illustration of an outer shell 20 made by the above process. The outer shell 20 is made up of the two component parts 17, 18 injected during the process shown in Figures lA and B. Said component parts 17, 18 are joined along a seam 21 running from one side edge 22 to a second side edge 23 of the outer shell 20. FIG. 2 further indicates the gating location 24 for the primary runner system 13 and the corresponding gating location 25 for the secondary runner system 14.

[0066] One factor to consider during the process is the relative melt temperature of the two materials. As stated above, the material having the highest injection temperature is usually injected first. In order to ensure that the temperature of the second material is sufficient for at least partially melting a cooperating edge of the first material, the injection temperature of the second material can be increased. The increased temperature can be higher than the injection temperature recommended by the manufacturer, but not higher than the degradation temperature of the material.

[0067] In the above example, the first material was a transparent resin that was tested at two different injection temperatures. The second material was an opaque resin injected at the same temperature in both tests. These tests are described in further detail below.

[0068] Further factors are the mould wall temperature, the injection speed, the delay time between injections and the injected component part temperature. For instance, the mould wall temperature is controlled to maintain the first component part at a desired temperature during rotation of the first component into the second injection position. In this way, the edge of the first component will not cause the injected second material to cool before the cooperating edges have melted together. The temperature of both components can also be maintained during the consecutive injections in order to minimize distortion of the outer shell during the subsequent cooling of the complete outer shell. As each injection station is supplied by an independent injection unit, injection speeds and pressures can be accurately controlled and adapted for each material being injected.

[0069] In addition to the tool design, additional considerations are the wall thickness of the injected component, the surface structure of the part from the primary runner system to avoid venting problems, the tool surface and temperature for demolding, the gating location for optimum adhesion between component parts in dependence of the flow path and how the part will be demolded, causing a force to be applied to the adhesion area between component parts.

[0070] In order to increase adhesion between the contacting edges of the two materials, the seam has been given a particular configuration. A prior art seam, as shown in FIG. 3, made by joining the same, two materials were used as a reference sample. The prior art sample was subjected to a comparative test using samples comprising a number of alternative seams according to the disclosure and a sample comprising a length of a homogenous opaque material having the same thickness as the reference sample. The seam according to the disclosure is shown in FIG. 4.

[0071] FIG. 3 shows a schematic illustration of a prior art seam between a transparent first component part 31 and an opaque second component part 32. The first and second component parts 31, 32 have the same wall thickness and are joined end-to-end by a straight, flat seam 33.

[0072] FIG. 4 shows a schematic illustration of a cross-section through a seam according to the disclosure. FIG. 4 shows a transparent first component part 41a and an opaque second component part 42a. The first and second component parts 41a, 42a have the same wall thickness of 3 mm and are joined end-to-end by a seam 43a comprising a number of steps. The seam extends over a distance 2.5 times the thickness of the second component part 42a in a direction transverse to the direction of the seam 43a between the component parts. The front surfaces of the respective joined component parts are completely flush with each other along the seam. In the region of the seam, the leading edge of the second component part 42a is arranged to overlap the first component part 41a in order to hide the seam 43a. The seam 43a will be described in further detail below (see FIG. 5). In FIG. 4, the steps are shown as distinct steps with right angled corners for clarity. However, in the finished seam between two injection molded components, at least the corners of the contacting surfaces were melted to form a fused seam. In order to achieve a desired strength, each corner of the said steps is arranged to melt during the second injection molding step. It has been found that by providing steps formed by substantially right angled corners along the entire length of the seam, the formation of a homogenous, strong seam is achieved. When the molten material injected during the second injection step reaches the solidified edge of the first component part, the corners facilitate the melting together of the first and second component parts. In order to ensure this, the temperature of the material to be injected and/or the temperature of the mould may be controlled to achieve the desired result.

[0073] FIG. 5 shows an enlarged view of the seam of FIG. 4 comprising a transparent first component part 41a and an opaque second component part 42a. The front edge of the first component part 41a is injection molded to form a number of distinct steps 44, 45, 46. The height of the steps is selected depending on the thickness of the dispenser wall adjacent the seam 43a. In this example, the dispenser wall thickness adjacent the seam is 3 mm and the height of the steps is selected based on this measurement. For instance, in a seam 43a connecting a transparent part 41a and an opaque part 42a, a first step 44 adjacent the outer surface 47 of the outer shell has been selected larger than a number of intermediate steps 45. This gives a distinct line separating the two parts 41a, 42a and facilitates filling of the mould adjacent the edge of the first component part 41a during the second injection molding step. A higher first step 46 adjacent the seam 43a will also prevent this portion of the outer shell from becoming partially transparent. Similarly, a final step 46 adjacent the inner surface 48 of the outer shell has been selected larger than the intermediate steps 45 to facilitate filling of the mould adjacent the edge of the first component part 41a. In the latter case, the steps 44, 46 provided adjacent both the outer and the inner surfaces 47, 48 have each been given a height of 0.2 mm. For a dispenser wall having a constant total thickness of 2 mm, these outer, first steps can be separated by a number of intermediate steps of 0.05 mm to 0.1 mm. In this case the intermediate steps have an equal height of 0.05 mm.

[0074] FIG. 6 shows a schematic enlarged section of a component part provided with multiple steps. This component part corresponds to the first component part 41a shown in FIG. 5. As described above, the front edge of the first component part 41a is injection molded to form a number of distinct steps 44, 45, 46 during a first injection molding step according to the disclosure. A first step 44 adjacent the outer surface 47 of the component part has a larger height than a number of intermediate steps 45. Similarly, a final step 46 adjacent the inner surface 48 of the component part has been selected larger than the intermediate steps 45 to facilitate filling of the mould adjacent the edge of the first component part 41a. The first component part 41a will be joined to the second component part 41b (see FIG. 5) during the second injection molding step.

[0075] FIG. 10 shows a schematic illustration of the component part 41a provided with a stepped edge 80 comprising a number of distinct steps 44, 45, 46 as shown in FIG. 6. In FIG. 11 it can be seen how the stepped edge 80 extends continuously from one side edge 81 of the component part 41a to a second side edge 82. Also visible are a plurality of recesses 49 extending along the stepped edge 80.

[0076] FIG. 11 shows an illustration of actual photographs of cross-sectional samples through an outer shell corresponding to the schematic cross-sections shown in FIG. 4. In FIG. 12, the outer shell has been cut in a transverse direction of the seam between the first and second component parts. Hence, FIG. 1A, corresponding to FIG. 4, shows a transparent first component part 41a and an opaque second component part 42a. The first and second component parts 41a, 42a have the same wall thickness of 3 mm and are joined end-to-end by a seam 43a comprising a number of steps. As can be seen from the Figure, the contact surfaces have been joined and the corners of the distinct steps were melted to form rounded surfaces and merged with the second component part 42a during the second injection molding step.

[0077] Moreover, a plurality of recesses 49 is formed in the inner surface 1 of the first component part 17 or 41a (FIGS. 2 and 4 to 6). The recesses 49 in the particular example do not have an undercut but may also be formed with an undercut at a specific undercut angle.

[0078] On the other hand, FIG. 9 also shows a number of recesses 50 which extend along a free edge 51 of a gate protrusion 24 extending from the free end 46 of the mating surface and having a partly circular shape. These recesses 50 comprise an undercut at an undercut angle in the particular example 10°. Yet, different undercut angles may be selected depending on the used material and the circumstances as explained earlier.

[0079] The undercut angle is defined as an angle of the side wall of the recess 49, 50 in cross-section relative to a line perpendicular to the inner surface of the first component part 17 at the opening of the recess 49, 50.

[0080] The recesses 49, 50 particularly serve for retaining the first component part 17 in the mould 19 before injecting the second component plastic material for forming the second component part 18.

[0081] Thus, the recesses 49, 50 are formed by protrusions 49′ and 50′ of the mould 19 as shown in FIGS. 7 and 8. The protrusions 49′ extend along the portion of the mould 19 at which the seam between the first component part 17 and the second component part 18 is to be located. This seam has been indicated at 21′ in FIG. 7. As will be apparent from FIG. 7, the protrusions 49′ extend along the entire length of the seam 21′. The protrusions 49′ are more clearly depicted in FIG. 8 in enlarged scale. The protrusions 49′ have a rectangularly shaped top view and rounded longitudinal side edges. Thus, the protrusions 49′ taper starting from the surface 17′ of the mould 19 so that there is no undercut. If the protrusions 49′ are considered to be the negative, the recesses 49 as shown in FIG. 9 will be the positive of the protrusions 49′.

[0082] The recesses 50 shown in FIG. 9 are formed by protrusions 50′. The protrusions 50′ are provided along a free edge or end 51′ of the surface 17′ of the mould corresponding to the free end 51 of the gate protrusion 24 (FIG. 9). Contrary to the protrusions 49′, the protrusions 50′ are provided with an undercut. For this purpose, the protrusions 50′ may be mushroom headed. For example, the side walls or at least two opposite side walls of the protrusions 50′ may be angled outwardly relative to a line perpendicular to the surface 17′ of the mould 19 to provide for the undercut. In this particular example, the undercut angle, that is the inclination of the side wall of the protrusion 50′ towards the outside and relative to a line perpendicular to the surface 17′ in cross-section, is about 10°. In other words, the protrusions 50′ widen or expand starting from the surface 17′.

[0083] Both, the protrusions 49′ and 50′ are disposed in a row. Yet, the protrusions 49′ have the same height along the length of the seam 21′. To the contrary, the height of the protrusions 50′ is highest in a center of the row and lowest at the opposite ends of the row as clearly visible from FIG. 8. This also applies to the recesses 49 and 50 formed by the protrusions 49′ and 50′.

[0084] It is also clear that the protrusions 49′ may be disposed at an equal pitch along the row (the distance between adjacent protrusions 49′ is the same along the row) or grouped, each group consisting of a plurality of protrusions 50′, such as two protrusions 50′, wherein the protrusions within one group are disposed at an equal pitch (distance to each other) and the groups are positioned at an equal pitch, however different than the pitch of the protrusions 50′ within one group. In the example in FIG. 8, there are four groups each consisting of two protrusions 50′. FIG. 9 shows an alternative configuration with respect to the recesses resulting from the protrusions 50′. In this context, four recesses 50 are shown which are disposed at equal pitch. It becomes also apparent that the recesses 50 in FIG. 9 are rectangular in top view, whereas the recesses 49 are square-shaped in top view. Yet, also circular recesses are conceivable.

[0085] The injection molding process incorporates as previously mentioned a first injection molding step in which the first component plastic material is injected into the first cavity 15. During this first injection molding step, first component plastic material flows around the protrusions 49′ and 50′. Upon cooling, the so formed first component part 41a is fixed and retained by engagement of the recesses 49 and 50 with the respective protrusions 49′ and 50′. Accordingly, the mating surface 43a of the first component part 43a is fixed in position within or on the mould 19 even during rotation in the direction A in FIGS. 1A and B and/or during shrinking when the plastic material is cooled. Thus, there is a negative provided by the mould 19 when closed to define the second cavity 16. Accordingly, any overflow of second component plastic material during the second injection molding step may be avoided. Thus, the inner surface 1 of the outer shell formed by the first component part 41a and a second component part 42a is flush as shown in FIG. 5 or 11 without any unintentional ridges or protrusions formed on the inner surface 1. This is particularly beneficial when the outer shell is used for a dispenser in which the product to be dispensed moves past the inner surface 1 at the seam. Due to the configuration without any protrusions or ridges, a damaging of the product to be dispensed which could potentially interfere with the protrusions or ridges may be avoided.

[0086] It is also clear from these drawings that the outer surface 2 of the first component part 41a and the second component part 42a may be flush. Because of the exact positioning, a gap formed between the step 44 and the free edge of the second component part 42a may be reduced to a minimum and even be closed and connected during the injection molding process. Accordingly, no dirt may accumulate in this gap which is particularly beneficial, if the dispenser is disposed in a delicate environment such as a hospital or clean rooms.

[0087] FIG. 12 shows a first example of a dispenser comprising an outer shell according to the disclosure. In this example, an outer shell 90 is formed by a transparent first component part 91 and an opaque second component part 92. The first component part 91 and the second component part 92 are joined by a seam 93 extending from a first side edge 94 to a second side edge 95 of the outer shell 90. The component parts 91, 92 can be joined by any one of the seams described in connection with FIGS. 6 to 9. The outer shell 90 is detachably joined to a rear dispenser section 96 in order to form a dispenser housing 97. The rear dispenser section 96 is arranged to be mounted on a vertical surface, such as a wall. In this example, the dispenser housing 97 is intended for a dispenser for a stack of paper towels or similar, which are removed through a dispenser opening 98 in a lower surface of the dispenser.

[0088] FIG. 13 shows a second example of a dispenser comprising an outer shell according to the disclosure. In this example, an outer shell 100 is formed by a transparent first component part 101 and an opaque second component part 102. The first component part 101 and the second component part 102 are joined by a seam 103 extending from a first side edge 104 to a second side edge 105 located along a lower delimiting section of the outer shell 100. The component parts 101, 102 can be joined by any one of the seams described above. The outer shell 100 is detachably joined to a rear dispenser section 106 in order to form a dispenser housing 107. The rear dispenser section 106 is arranged to be mounted on a vertical surface, such as a wall. In this example, the dispenser housing 107 is intended for a dispenser for a roll of paper or similar, which is removed through a dispenser opening 108 in a lower surface of the dispenser.

[0089] FIG. 14 shows a third example of a dispenser comprising an outer shell according to the disclosure. In this example, an outer shell 110 is formed by a central transparent first component part 111 and an upper and a lower opaque second component part 112a, 112b. The first component part 111 and the second component parts 112a, 112b are joined by seams 113a and 113b, respectively. Both seams 113a, 113b extend in parallel from a first side edge 114 to a second side edge 115 of the outer shell 110. The component parts 111, 112a, 112b can be joined by any one of the seams described in connection with FIGS. 6 to 9. The outer shell 110 is detachably joined to a rear dispenser section 116 in order to form a dispenser housing 117. The rear dispenser section 116 is arranged to be mounted on a vertical surface, such as a wall. In this example, the dispenser housing 117 is intended for a dispenser for a stack of paper towels or similar which are removed through a dispenser opening 118 in a lower surface of the dispenser.

[0090] When selecting materials, it may be determined that the resins used are generally compatible with no antagonistic effects between resins. Suitable materials for use in the above method are acrylonitrile butadiene styrene (ABS) plastics and/or methyl methacrylate-ABS (MABS) plastics. However, these materials are given by way of example only and the disclosure is not limited to these materials. The materials tested in the examples below are Terlux® TR2802 MABS (BASF Corp.) or Polylux® C2 MABS (A. Schulman GmbH) for the transparent first component part and Polyman® M/MI A40 ABS (A. Schulman GmbH) for the opaque second component part.

[0091] The disclosure is not limited to the above examples, but may be varied freely within the scope of the appended claims. For instance, in the above examples a combination of transparent and opaque materials are described. In addition, combinations of one or more colored and/or transparent materials may be used. Also, the examples describe a single seam extending horizontally or at an angle across the outer (or front) surface of the outer shell. Alternative solutions may comprise one or more seams arranged vertically or to enclose a single corner. The seams need not only be located along a straight line as described above, but can also be given a curved, wavy or an irregularly shaped line. To this end, the embodiments described above are only descriptions of preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Various variations and modifications can be made to the technical solution of the present invention by those of ordinary skill in the art, without departing from the design of the present invention. The variations and modifications should all fall within the claimed scope defined by the claims of the present invention.