Tool shape and method for manufacturing a metal foam product, metal foam product

Abstract

The invention relates to a tool mold (20) for manufacturing a metal foam product (60) with a tab (70) from an unfoamed semi-finished product (50), comprising a mold chamber (29) for receiving the semi-finished product (50) during manufacturing, wherein the mold chamber (29) is bounded at least at one point by a tab support section (30), the tab support section (30) comprising a thermally insulating insulating material (40) that reduces the heat flow (80) to the tab (70). The invention further relates to a method for manufacturing a metal foam product (60) from an unfoamed semi-finished product (50), wherein a tool mold (20) with an insulating material (40) in the region of a tab support section (30) is used.Furthermore, the document discloses a metal foam product (60) comprising at least one metal plate (61) and a metal foam (65) attached thereto, wherein the metal plate (61) forms a tab (70) projecting beyond the metal foam (65).

Description

[0001] The invention relates to the manufacture of metal foam products, in particular to a mold used therefor and the method applied. Furthermore, the invention relates to an advantageous metal foam product.

[0002] Metal foam products, i.e., products comprising a metal foam, are known from the prior art. In one possible embodiment, during the production of such metal foam products, a semi-finished product comprising a metal and a suitable blowing agent is placed in the mold cavity of a tool, and the tool is heated, for example, in an oven. The heat activates the blowing agent and foams the metal. The resulting metal foam product has advantageous properties, particularly with regard to density.

[0003] The object of the invention is to provide a solution with which metal foam products can be manufactured with further advantages.

[0004] According to the invention, this is achieved by a tool mold for producing a metal foam product with a tab made of an unfoamed semi-finished product, with a mold space for receiving the semi-finished product during production, wherein the mold space is delimited at least at one point by a tab support section, wherein the tab support section comprises a thermally insulating insulation material which reduces the heat flow to the tab.

[0005] In a method according to the invention for producing a metal foam product from an unfoamed semi-finished product, a tool mold with an insulating material in the region of a tab support section is used.

[0006] The metal foam product produced with the solution according to the invention comprises at least one metal plate and a metal foam attached thereto, wherein the metal plate forms a tab that protrudes from the metal foam. In particular, the tab can be integral with the metal plate.

[0007] The use of the insulating material allows the production of a metal foam product with a tab. The insulating material prevents the tab from overheating and melting during the manufacturing process. In the finished metal foam product, the tab can be used, for example, to secure the metal foam product. With conventional metal foam products, the tab must be attached in an additional step after production, for example, by welding, soldering, riveting, gluing, or similar processes. With the solution according to the invention, this additional step can be eliminated.

[0008] The solution according to the invention can be further improved with the following further developments and embodiments, each of which is advantageous in itself and can be combined with one another as desired.

[0009] According to an advantageous embodiment, the insulation material can form a support surface for the tab. This maximizes the reduction of heat flow to the tab and keeps the design simple. In particular, the insulation material can have direct contact with the tab.

[0010] In another embodiment, the insulating material can be covered by a metal part of the mold. Thus, the metal is located between the tab and the insulating material. The insulating material can be embedded in the rest of the mold and enclosed by the metal. This can have the advantage that the tab is contacted by the metal, which achieves a more even distribution of the temperature prevailing at the tab than the insulating material.

[0011] To achieve particularly good insulation, the insulation material in the area of ​​the tab can have a thickness of at least 1 mm, at least 2 mm, or at least 3 mm. The required thickness can depend on the shape of the semi-finished product or the metal foam product, for example, the thickness of the semi-finished product at the point where the insulation material is applied. Thin coatings of an insulation material, in particular, can be considered insufficient, for example if the thickness is only a few hundred micrometers. Such coatings can fulfill various functions, such as corrosion protection or reducing friction. Furthermore, the thickness of the insulation material can be selected so that heat can still reach other parts of the semi-finished product or metal foam product and foaming is achieved. Maximum thicknesses can be considered to be 2 cm, 1 cm, or 5 mm, for example.Experiments have shown that a thickness of 2 to 5 mm is a good compromise for some cases.

[0012] If the insulation material ensures that the maximum temperature prevailing at the tab during production of the metal foam product is at least 10 K lower than at adjacent locations, at least partial melting of the tab can be reliably prevented. A location can be considered an adjacent location if the shortest connecting line between the location and the semi-finished product or the metal foam product is at least 2 mm, at least 3 mm, or at least 4 mm. A value of 5 cm, 2 cm, or 1 cm can be considered an upper limit.

[0013] In the solution according to the invention, in a tool mold with insulation material, the maximum temperature prevailing on the tab during production of the metal foam product can be at least 10 K lower than in an otherwise identically shaped tool mold without insulation material.

[0014] In an advantageous embodiment, the insulation material can be part of or form a replaceable insulation element. Such a mold can be used longer than a mold with a non-replaceable insulation element. The replacement can be carried out with or without destroying the old, worn-out insulation element.

[0015] In one possible embodiment, the insulation material may comprise a ceramic material. Such materials can often withstand the high temperatures encountered during manufacturing without significant deformation.

[0016] The material for the rest of the mold preferably comprises a metal, such as iron or steel. The material should have a melting point significantly higher than the temperature required for production, especially for foaming. A difference of at least 50 °C or K can be considered "significant."

[0017] The mold is preferably solid, meaning the material has a certain minimum thickness throughout, such as 1 cm, 2 cm, or 5 cm. To ensure sufficient stability, the thickness in the area of ​​the insulation material should be at least the thickness of the insulation material plus 5 mm, preferably plus 1 cm.

[0018] The tool mold can consist of several parts. For example, the tool mold can comprise a pot-shaped part and a lid. The different parts can comprise different materials. For example, the pot-shaped part can comprise a ferrous material to enable high heat capacity and even heat distribution. The lid can comprise a graphite material to enable it to be moved easily. The pot-shaped part can in turn consist of a single part or several parts that, when assembled, form a pot shape. The lid can be designed to close off or form the mold cavity with the pot-shaped part. It can be at least partially complementary to parts or sections of the pot-shaped part.

[0019] To keep the design simple, the mold can be designed to reduce heat flow through the insulation material on only one side of the tab. This can reduce the temperature at the tab sufficiently to effectively prevent softening or melting.

[0020] This can be achieved, for example, by having the tool mold have an insulating material on only one side of the tab.

[0021] In other embodiments, the mold can be designed so that insulation material is present on both sides of the tab during production. This allows the corresponding heat flow to be reduced on both sides and thus more significantly than with a one-sided solution.

[0022] The “sides” can be understood here as the two complementary half-spaces defined by the plane of the tab.

[0023] To achieve effective heat flow reduction, the mold can be designed so that at least 50% of the surface of the tab is covered by the insulation material on at least one side. If the tab rests directly on the insulation material, this can be the case, for example, if at least 50% of the surface of the tab rests on the insulation material on one side.

[0024] According to an embodiment in which production can be particularly simple since it allows easy insertion of the semi-finished product, the tab in the tool mold can be supported only on one side.

[0025] In other designs, the tab can be supported on both sides. This ensures that the shape of the tab is maintained during production and that it does not warp.

[0026] Furthermore, the tool mold, in particular the tab support section, can be used to shape the tab. For example, sections of the tab can be bent, punched, or embossed by the tool mold during production.

[0027] In one method, a tool mold with an insulating material in the area of ​​a tab support section may be used.

[0028] The term "tab" can, in particular, refer to a flat section of an element, such as a sheet or plate. The section can protrude or protrude from a remainder of the element. It can be accessible from several sides, in particular from two opposite sides. The tab can encompass an end or an edge of the element.

[0029] In one possible embodiment, the metal foam product may comprise two metal plates and a metal foam located between the two metal plates, wherein at least one of the metal plates forms a tab projecting from the metal foam.

[0030] Holes for fastening elements such as screws or rivets can be drilled or punched into the tab before or after the foaming step.

[0031] To enable secure fastening, the tab can be designed as a flange. A flange can be present continuously along a circumferential direction of the metal foam product, with the thickness of the tab corresponding to the thickness of one of the metal plates. This can simplify production, as no special treatment of the tab is required. Deviations in thickness within the range of normal manufacturing tolerances are understood to be covered. Typical manufacturing tolerances can vary depending on the industry and requirements and can be, for example, + / - 20%, + / - 10%, + / - 5%, or + / - 3%.

[0032] The invention will be explained in more detail below using advantageous embodiments with reference to the drawings. The advantageous further developments and embodiments presented are independent of one another and can be combined with one another as required in the specific application.

[0033] They show: Fig. 1 a schematic sectional view through a first embodiment of a tool mold with a semi-finished product arranged therein; Fig. 2 a schematic sectional view through a second embodiment of a tool mold; Fig. 3 a schematic sectional view through a third embodiment of a tool mold; Fig. 4 is a schematic sectional view through a fourth embodiment of a tool mold; Fig. 5 is a schematic perspective view of an embodiment of a metal foam product; Fig. 6 a schematic top view of another embodiment of a tool mold; Fig. 7 a schematic, side sectional view through the embodiment of the Fig. 6; Fig. 8 a detailed view of area B Fig. 7; Fig. 9 is a schematic perspective view of the embodiment of the Fig. 6; and Fig. 10 a schematic top view of another embodiment of a tool mold.

[0034] In the Fig. 1 to 4 and 6 to 10 show several possible embodiments of a tool mold 20. The tool molds 20 are each designed to produce a metal foam product 60 with a tab 70 from a semi-finished product 50. Such a metal foam product 60 is shown by way of example in Fig. 5 shown.

[0035] Each tool mold 20 comprises a pot-shaped part 21 and a matching lid 22, wherein in the Fig. 6 to 10, only the cup-shaped part is shown. These together form a mold cavity 29, into which the semi-finished product 50 is inserted during production. The mold 20 is then heated, for example, in a furnace. The mold 20 is often also called a permanent mold. It can alternatively be referred to as a forming tool or hollow mold.

[0036] In Fig. 1 also shows such an inserted semi-finished product 50. A mixture of a metal powder and a propellant is located between a first plate 61 and a second plate 62. The heat generated melts the metal powder and activates the propellant. The mixture expands along an expansion direction X. A metal foam 65 is formed between the two plates 61, 62, which is bonded to the plates 61, 62.

[0037] The first plate 61 is larger in area than the second plate 62 and the metal foam 65. The first plate 61 forms a laterally projecting tab 70, which can be used, for example, to attach the metal foam product 60. For this purpose, holes 66 can be provided in the tab 70 through which, for example, screws or rivets can be inserted. The holes 66 can be created before or after the foaming step.

[0038] The tab 70 is integral with the first plate 61. The plates 61, 62 can each be formed, for example, from a metal sheet. Accordingly, the plates 61, 62 can have a constant thickness. Thus, the thickness 68 of the first plate 61 also corresponds to the thickness 78 of the tab 70. The thickness is measured along a height direction H, which can be parallel to the expansion direction X. Along the height direction H, the metal foam 65 is arranged between the first plate 61 and the second plate 62. Together, they form a sandwich structure with the metal foam 25 in the center.

[0039] In the example shown, the tab 70 is designed as a flange 77 that extends along the entire circumferential direction U. The tab 70 protrudes laterally from the metal foam 65. It forms a section 79 of the first plate 61 and, in particular, also encompasses part of the edge.

[0040] The production of such a metal foam product 60 is not possible with previous tool molds, since during the foaming step temperatures close to the melting temperature of the materials of the plates 61, 62 prevail and a laterally projecting tab melts due to the residual heat in the tool mold 20.

[0041] However, production is possible with the tool molds 20 shown. To reduce the heat flow 80 to the tab 70, insulation material 40 is located in the area of ​​a tab support section 30, which in this case delimits the mold cavity 29. Accordingly, the maximum temperature prevailing in the area of ​​the tab 70 during the manufacturing process is lower than without insulation material and lower than at adjacent locations 35. Consequently, the tab 70 does not melt.

[0042] In the examples shown, the insulating material 40 forms an insulating part 41. The insulating part 41 is a replaceable part 42 that can be connected to the remainder 43 of the cup-shaped part 21. For example, it can be repeatedly attached and detached from the remainder 43 without causing any damage. In other examples, the insulating part 41 can be detached from the remainder 43 by destruction, for example, when an insulating part 41 is consumed by the manufacturing process and a new insulating part 41 is to be inserted.

[0043] The insulation material 40 can, in particular, be a ceramic material. The commercially available Insulair NP 650 Plus, for example, can be particularly advantageous in terms of temperature and dimensional stability.

[0044] In the embodiments shown, there is direct contact between the tab 70 and the tab support section 30. The tab 70 rests on a support surface 33 of the tab support section 30.

[0045] In the embodiment according to Fig. 1, insulating material 40 is present only in the pot-shaped part 21. The cover 22 here consists of a third material that differs from the material of the remainder 43, for example, an iron or steel material, and the insulating material 40. To allow the cover 22 to move easily, it can be made, for example, of graphite or a material containing graphite.

[0046] In the embodiment according to Fig. 2, the entire cover 22 is made of the insulating material 40. This allows the heat flow from the top to be reduced.

[0047] In the example after Fig. 3, insulation parts 41 made of insulating material 40 are present on both the cover 22 and the pot-shaped part 21. This can often be sufficient to influence the heat flow.

[0048] According to the embodiment shown in Fig. As shown in Figure 4, insulation material 40 is present only on a first side 71. The first side 71 and a complementary second side 72 are separated by a plane E defined by the tab 70.

[0049] Unlike the previous embodiments, the design according to Fig. 4 the tab 70 must be supported on both sides.

[0050] In the Fig. In the embodiments shown in Figures 1 to 4, the insulation material 40 completely covers the surface 85 of the tab 70 during the manufacturing process. This minimizes heat flow. In other embodiments, it may be sufficient if less surface 85 is covered, for example, 50% of the surface 85.

[0051] The thickness 48 of the insulation material 40 also plays a role. Depending on the size of the metal foam product 60 to be manufactured and the tab 70, the sufficient thickness 48 can be determined experimentally. In practice, depending on the application, a thickness 48 can be at least 2 mm, preferably at least 3 mm, more preferably at least 4 mm for manufacturing reasons. However, to allow heat flow to other component areas, the thickness should not be chosen too large. For example, a value of 2 cm, preferably 1 cm, can be considered an upper limit.

[0052] In the Fig. 6 to 9, a further embodiment of a pot-shaped part 21 of a tool mold 20 is shown, wherein in the Fig. 7 the cutting plane along the Fig. 6 level marked A.

[0053] Unlike the previous embodiments, the tab support section 30 here not only comprises the insulation part 41. Rather, a circumferential wall 90 next to the insulation part 41 is also part of the tab support section 30. The insulation part 41 lies in a trench 99 defined by the wall 90 further away from a center of the mold space 29 than the wall 90. When the insulation part 41 is attached, the upper sides of the wall 90 and the insulation part 41 are aligned and together form the support surface 33. Such a configuration has the advantage that during foaming, no still liquid metal foam can penetrate to the insulation part 41.

[0054] In the example shown, a width 91 of the wall 90 measured perpendicular to the expansion direction X is 5 mm and thus corresponds approximately to the depth 91 of the trench 99 behind the wall 90 when the insulation part 41 is not installed, which is 4.55 mm in this example. With a thickness of the insulation part 41 of 2 mm, a height 93 of 2.55 mm remains for the tab 70.

[0055] A depth 94 of the mold cavity 29 measured in the central area here is 15.1 mm and is thus approximately six times the height 93. A bottom of the mold cavity 29 measures approximately 4.9 mm at this point, resulting in a thickness 95 of 20.0 mm for the cup-shaped part 21.

[0056] When designing according to Fig. 6 to 9, holes 25 are provided on the cup-shaped part 21 for connection to a cover not shown, for example with bolts.

[0057] The design according to Fig. 10 is compared to the design according to Fig.9. Optimized for heat flow and weight, but more complex to manufacture. Instead of flat sections, only relatively narrow projections 27 are present. Due to the lack of material near the tab support section 30, there is less heat capacity and the heat transferred to the tab 70 is lower. Reference symbol 20 Tool shape 21 pot-shaped part 22 lids 25 holes 27 lead 29 Forming room 30 Tab support section 33 Support surface 35 neighboring place 36 connecting line 40 insulation material 41 Insulation part 42 replaceable part 43 Rest of the pot-shaped part 48 thickness 50 semi-finished products 60 metal foam product 61 first record 62 second plate 63 Scope 65 metal foam 66 holes 68 thickness 70 tab 71 first page 72 second page 77 Flange 78 thickness Section 79 80 heat flow 85 area 90 Wall 91 width 92 depth 93 height 94 depth 95 thickness 99 Trench E Tab level H Altitude direction U circumferential direction X Expansion direction

Claims

[1] Tool mold (20) for producing a metal foam product (60) with a tab (70) made of an unfoamed semi-finished product (50), with a mold space (29) for receiving the semi-finished product (50) during production, wherein the mold space (29) is delimited at least at one point by a tab support section (30), wherein the tab support section (30) comprises a thermally insulating insulation material (40) which reduces the heat flow (80) to the tab (70). [2] Tool mold (20) according to claim 1, wherein the insulating material (40) forms a support surface (33) for the tab (70). [3] Tool mold (20) according to claim 1 or 2, wherein the insulating material (40) in the region of the tab (70) has a thickness (48) of at least 2 mm, at least 3 mm, or at least 4 mm. [4] Tool mold (20) according to one of claims 1 to 3, wherein the insulating material (40) causes the maximum temperature prevailing at the tab (70) during the production of the metal foam product (60) to be at least 10 K lower than at adjacent locations (35). [5] Tool mold (20) according to one of claims 1 to 4, wherein in a tool mold (20) with insulating material (40) the maximum temperature prevailing at the tab (70) during the production of the metal foam product (60) is at least 10 K lower than in a tool mold (20) without insulating material (40). [6] Tool mold (20) according to one of claims 1 to 5, wherein the insulating material (40) is part of a replaceable insulating element (41, 42). [7] Tool mold (20) according to one of claims 1 to 6, wherein the insulating material (40) comprises a ceramic material. [8] Tool mold (20) according to one of claims 1 to 7, wherein the tool mold (20) is designed such that the heat flow (80) through the insulation material (40) is reduced only on one side (71) of the tab. [9] Tool mold (20) according to one of claims 1 to 8, wherein the tool mold (20) is designed such that at least 50% of the surface of the tab is covered by the insulating material (40) on at least one side (71). [10] Tool mold (20) according to one of claims 1 to 9, wherein the tab (70) is supported in the tool mold (20) only on one side. [11] Method for producing a metal foam product (60) from an unfoamed semi-finished product (50), wherein a tool mold (20) with an insulating material (40) is used in the region of a tab support section (30). [12] Metal foam product (60) comprising at least one metal plate (61) and a metal foam (65) attached thereto, wherein the metal plate (61) forms a tab (70) projecting relative to the metal foam (65). [13] Metal foam product (60) according to claim 12, wherein the tab (70) is designed as a flange (77). [14] Metal foam product (60) according to claim 12 or 13, wherein the thickness (78) of the tab (70) corresponds to the thickness (68) of the metal plate (61). [15] Metal foam product (60) according to one of claims 12 to 14, comprising two metal plates (61, 62) and a metal foam (65) located between the two metal plates (61, 62), wherein at least one of the metal plates (61) forms a tab (70) projecting relative to the metal foam (65).

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