Method and Mold for Producing a Sandwich Component

Abstract

A method and compression mold are provided for producing a sandwich component, in which an outer shell and an inner shell are compressed, together with foam particles in a cavity between the shells, which cavity is formed by two mold halves of a mold, under pressure and at an increased temperature to form the sandwich component. At least one mold half is heated in a first temperature-control zone to a higher maximum temperature than in a second temperature-control zone.

Claims

1.-13. (canceled)

14. A method for producing a sandwich component, comprising: compressing an outer shell and an inner shell together with foam particles lying between them in a cavity, which cavity is formed by two mold halves of a compression mold, under pressure and at elevated temperature to provide the sandwich component, wherein at least one mold half is heated to a higher maximum temperature in a first temperature-control zone than in a second temperature-control zone.

15. The method according to claim 14, wherein both mold halves have first and second temperature-control zones and are heated to a higher maximum temperature in the first temperature-control zone than in the second temperature-control zone.

16. The method according to claim 15, wherein the maximum temperature in the first temperature-control zone is set in such a way that there is an at least partial collapse of the foam particles in a bordering component portion, and the maximum temperature in the second temperature-control zone is set in such a way that the foam particles in a bordering component portion bond to one another and to the outer shell and inner shell without collapsing.

17. The method according to claim 14, wherein the maximum temperature in the first temperature-control zone is set in such a way that there is an at least partial collapse of the foam particles in a bordering component portion, and the maximum temperature in the second temperature-control zone is set in such a way that the foam particles in a bordering component portion bond to one another and to the outer shell and inner shell without collapsing.

18. The method according to claim 14, further comprising: inserting the outer shell and the inner shell into respective mold halves of the compression mold; partially closing the compression mold, to leave a mandated gap between the outer shell and the inner shell; introducing the foam particles into the gap between the outer shell and the inner shell; and subsequently fully closing the compression mold.

19. The method according to claim 14, further comprising: inserting the outer shell and the inner shell into respective mold halves of the compression mold; fully closing the compression mold, to leave a residual cavity between the outer shell and the inner shell; and filling the residual cavity with the foam particles, which are introduced into the cavity under pressure.

20. The method according to claim 14, wherein the first temperature-control zone is configured in a portion, of one mold half or of both mold halves, in which a height of the cavity corresponds substantially to a sum total of an outer shell thickness and an inner shell thickness.

21. The method according to claim 14, wherein the first temperature-control zone is configured in a portion, of one mold half or of both mold halves, in which a height of the cavity is lower than 50 percent of a maximum height of the cavity, or lower than 30 percent of the maximum height of the cavity, or lower than 20 percent of the maximum height of the cavity.

22. The method according to claim 14, wherein the outer shell is configured as a shaped sheet-metal part or fiber-reinforced plastics component, and the inner shell is configured as a shaped sheet-metal part or fiber-reinforced plastics component.

23. A compression mold for producing a sandwich component, comprising: two mold halves which are movable relative to one another and which, in a closed state, enclose a cavity in a shape of a component to be produced; two temperature-control apparatuses by which, in at least one mold half, a first temperature-control zone and a second temperature-control zone are temperature-controllable independently of one another; and a control device which is in an operative connection with the two temperature-control apparatuses and is configured to heat the first temperature-control zone to a higher temperature than the second temperature-control zone.

24. The compression mold according to claim 23, wherein both mold halves each have first and second temperature-control zones which are temperature-controllable independently of one another by the two temperature-control apparatuses.

25. The compression mold according to claim 23, wherein temperature control is accomplished via a temperature-control medium which is passed through temperature-control channels provided in or on the mold half.

26. The compression mold according to claim 23, further comprising: a feed apparatus for introducing foam particles into an interior of the cavity via feed openings configured in a mold half.

27. The compression mold according to claim 23, wherein the first temperature-control zone is configured in a portion, of one mold half or of both mold halves, in which a height of the cavity is lower than 50 percent of a maximum height of the cavity, or lower than 30 percent of the maximum height of the cavity, or lower than 20 percent of the maximum height of the cavity.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG. 1 shows a schematic method procedure;

[0042] FIG. 2 shows a schematic temperature regime during the method;

[0043] FIG. 3 shows an illustrative compression mold; and

[0044] FIGS. 4 and 5 show detailed views of a further illustrative compression mold.

DETAILED DESCRIPTION OF THE DRAWINGS

[0045] In step A of the method, an inner shell 110 and an outer shell 120 are inserted into a compression mold, such as the compression mold 1 shown in FIG. 3, for example. The inner shell 110 is fixed for example on the upper mold half 10, by means of reduced pressure (suction), for example, and the outer shell 120 is inserted into the lower mold half 20. The inner shell 110 and the outer shell 120 may be configured, for example, as fiber-reinforced plastics components or sheet-metal components. The inner shell 110 and the outer shell 120 already have a shape which models the surface profile of the sandwich component 100 to be manufactured. Inner shell 110 and outer shell 120 lie against the corresponding mold half 10, 20. The inner shell 110 and the outer shell 120 are configured, for example, as fiber-reinforced plastics components.

[0046] In step B, the foam particles 130 are then introduced into the compression mold 1 and compressed under pressure and at elevated temperature. As elucidated in more detail below with reference to FIG. 2, at least one mold half of the compression mold, however, has two temperature-control zones Z1 and Z2, in which the mold half is heated to differing maximum temperatures. Under the influence of the elevated temperature and pressure, the foam particles 130 are fused to one another to form a beaded foam and joined to the inner shell 110 and the outer shell 120.

[0047] There are various possible ways of introducing the foam particles. Where the crack-gap process is used, the compression mold 1 is closed except for a mandated gap, leaving a void between the outer shell 110 and the inner shell 120. The foam particles 130 are introduced into the void through one or more feed openings 40 in a mold half 20, and fill this void. The foam particles may be, for example, EPP foam particles. The compression mold 1 is then moved into the closing position. The pressure generated in this operation causes compaction of the foam particles 130. During this the mold halves 10, 20 are heated.

[0048] In the case of the back-pressure process, the compression mold 1 with the inserted inner shell 110 and outer shell 120 is closed fully and the foam particles 130 are introduced under pressure into the residual cavity which remains. The mold halves 10, 20 may be heated during the introduction of the foam particles 130 or only subsequently. Severe heating during the filling of foam particles 130 may contribute to the filling of only narrow “adhesive gaps” between outer shell and inner shell.

[0049] Where the crack-gap process and back-pressure process are combined, the compression mold 1 is closed except for a mandated gap and the foam particles 130 are introduced under pressure into this gap and already compacted. The compression mold 1 is subsequently closed fully, producing a further compaction.

[0050] When the foam particles 130 are joined to the inner shell 110 and the outer shell 120 to give the sandwich component, the mold halves 10, 20 are subsequently cooled in step C.

[0051] In step D, the compression mold 1 is opened and the sandwich component 100 can be withdrawn.

[0052] FIG. 2 shows an illustrative temperature profile during the method. In this profile, the dashed line T1 shows the temperature profile in a first temperature-control zone in the compression mold 1, and the continuous line T2 shows the temperature profile in a second temperature-control zone in said mold.

[0053] During step A, the mold halves 10, 20 are already slightly heated, to a temperature, for example, in the range from 60 to 110 degrees Celsius (° C.). During step B, the temperature is increased to a maximum T1max and T2max. Taking the example of a crack-gap process, for example, during the introduction of the foam particles between the outer shell 110 and the inner shell 120, the temperatures are increased to a greater extent, and at the point in time when the compression mold 1 is moved into its closing position in step C, the temperature profiles each attain their maximum, T1max and T2max, in both temperature-control zones. The first temperature-control zone Z1, however, is heated to a markedly higher temperature than the second temperature-control zone. For example, the maximum temperature T1max in the first temperature-control zone Z1 may be 165° C., and the maximum temperature T2max in the second temperature-control zone Z2 may be 145° C. As a result of the higher temperature in the first temperature-control zone Z1, the foam particles are heated, for example, to an extent such that they undergo at least partial melting and undergo partial or full collapse under the pressure of the compression mold, whereas the foam particles in the second temperature-control zone Z2 merely bond to one another and to the shells. When the compression mold 1 and the inserted materials are fully heated, a cooling takes place in step C, for which the temperature in both temperature-control zones is reduced, to a temperature of 100° C., for example. Subsequently the mold 1 can be opened in step D and the sandwich component 100 withdrawn. The specified temperatures are illustrative temperatures for the use of EPP foam beads and may adopt different values in the case of different materials.

[0054] FIG. 3 is a schematic view in section of a compression mold 1 in a closing position. The compression mold 1 is embodied as a positive mold and has a first mold half 10 and a second mold half 20, which in the closed state surround a cavity 30. In a mold half 10 there are feed openings 40 provided, through which foam particles 130 can be introduced into the cavity 30 by means of a feed apparatus 50.

[0055] The mold halves 10, 20 are temperature-controllable. Both in the first mold half 10 and in the second mold half 20 there are two temperature-control zones Z1 and Z2 configured that are temperature-controllable independently of one another. Provided in each temperature-control zone are channels in the mold half. For reasons of clarity, the channels 60 in the first temperature-control zone Z1 are each represented as solid circles, the channels 70 in the second temperature-control zone Z2 as open circles.

[0056] The channels 60 in the first temperature-control zone Z1—both in the first and in the second mold half 10, 20—are in communication with a first temperature-control apparatus 62, which is able to pass a temperature-control medium, such as water, for example, through the channels 60. The channels 70 of the second temperature-control zone Z2 are in communication with a second temperature-control apparatus 72, which is likewise able to pass a temperature-control medium through the channels 70. Additionally provided is a control device 80, which is in an operative connection with the first and second temperature-control apparatuses 62, 72, controls the temperature-control apparatuses, and is set up, for example, to heat the first temperature-control zone Z1 to a higher temperature than the second temperature-control zone Z2. The control device 80 is set up more particularly to control a temperature profile T1, T2, as is described in FIG. 2.

[0057] In the compression mold 10, in accordance with the method described above, a sandwich component 100 has been produced, in which an outer shell 110 and an inner shell 120 are bonded to a beaded foam core 130 lying between them. The sandwich component 100 is a component having different component thicknesses.

[0058] The first temperature-control zone Z1, in which a higher maximum temperature is reached, is configured in regions of the mold halves 10, 20 in which the sandwich component has a flat configuration, such as in regions, for example, in which the height of the cavity 30 corresponds substantially to the sum total of outer shell 110 thickness and inner shell 120 thickness, or in regions in which the height of the cavity is lower than 50 percent of the maximum height of the cavity, or lower than 30 percent of the maximum height of the cavity or lower than 20 percent of the maximum height of the cavity.

[0059] FIG. 4 and FIG. 5 show details of an alternative compression mold 1A in a schematic view. In the compression mold 1A, untrimmed shells are further-processed to give the sandwich component, and are trimmed jointly in a downstream method step, by milling, punching or with water-jet trimming, for example. The cavity 30 is embodied accordingly and on the marginal side, for example, has regions for accommodating projecting dry fiber ply portions. The dashed lines in FIGS. 4 and 5 indicate where the trimming is approximately to take place. It is of course also possible for shells that have already been trimmed to be introduced into a mold 1, 1A of the invention, whose cavity can be adapted accordingly.

[0060] The compression mold 1A differs from the compression mold 1 from FIG. 3 in that the channels 60, 70 are arranged not in the mold halves 10, 20, but rather on the mold halves 10, 20. For reasons of illustration, the channels 60 of the first temperature-control zone Z1 are show as solid squares, and the channels 70 of the second temperature-control zone Z2 as open squares.

[0061] FIG. 4 shows a portion of the mold 10A in which the cavity 30 and hence the component 100 has a large height and a relatively thick foam core is configured. Only in a narrow marginal region R1 are the outer shell 120 and the inner shell 110 to be brought together again. Configured in this marginal region R1, in the upper mold half 10, is an additional temperature-control zone Z1 having a higher maximum temperature. On the opposite side there is only one temperature-control zone Z2.

[0062] FIG. 5 shows a different portion of the same mold 10A. In this portion the cavity 30 and hence the component 100 have a small height, and in a marginal region R2 a wide flange is to be configured, in which the outer shell 120 and the inner shell 110 are brought together again. The additional temperature-control zone Z1, with a higher maximum temperature, is configured here in the upper mold half 10, over the entire flat region and the flange region, and additionally in the lower mold half 20 in the flange region.

[0063] In the first or additional temperature-control zone Z1, the compression mold 1, 1A is heated to a greater extent than in the second temperature-control zone; see FIG. 2. As a result, the foam particles 130 can be made to collapse and melt in a targeted manner in relatively flat component portions, thereby preventing unwanted local increase in the internal mold pressure and reducing impressions on the component surface.

[0064] Although in the illustrative compression molds 1 and 1A a first and second temperature-control zone is provided in each mold half 10, 20, it may also be the case that only one of the two mold halves 10 or 20, has two temperature-control zones Z1 and Z2 which are temperature-controllable independently of one another.