VISCOELASTIC DAMPING BODY AND METHOD FOR PRODUCING SAME

Abstract

The invention relates to a method for producing a viscoelastic damping body (1, 20, 30), comprising at least one spring element (4) and at least one damping element coupled thereto, wherein the method is characterized in that the damping element and optionally also the spring element (4) are produced by means of a 3-D printing method. The invention further relates to a viscoelastic damping body (1, 20, 30) that is or can be produced according to such a method and to a volume body comprising or consisting of a plurality of such damping bodies (1, 20, 30).

Claims

1-15. (canceled)

16. A process for the production of a viscoelastic damping body comprising at least one spring element and at least one damping element coupled thereto, wherein the damping element, and optionally also the spring element, is produced by way of a 3D printing process.

17. The process as claimed in claim 16, wherein the damping body or the damping element, to some extent or entirely, is configured as hollow body filled with at least one fluid and has at least one open passage, where the fluid is in particular selected from air, nitrogen, carbon dioxide, oils, water, hydrocarbons and hydrocarbon mixtures, ionic liquids, electrorheological, magnetorheological, Newtonian, viscoelastic, rheopectic and thixotropic liquids and mixtures of these.

18. The process as claimed in claim 17, wherein the number of open passages provided per cm.sup.2 of external surface of the damping element or of the damping body is from 0.01 to 100, and/or the diameter of the open passages is mutually independently from 10 to 5000 μm.

19. The process as claimed in claim 17, wherein only after the production of the hollow body are the open passages produced, in particular via melting of a sacrificial material or chemical dissolution from the wall of the damping element.

20. The process as claimed in claim 16, wherein the spring element is configured in such a way that the compressive strength of the damping body is from 0.01 to 1000 kPa, measured in accordance with DIN EN ISO 3386-1:2010-09, in particular from 0.1 to 500 kPa, or from 0.5 to 100 kPa.

21. The process as claimed in claim 16, wherein the spring element and the damping element of a damping body have been realized in a component, in particular in the form of a hollow body which has at least one open passage and has more than one narrowed region.

22. The process as claimed in claim 16, wherein a large number of spring elements and damping elements have been installed in parallel and/or sequentially with respect to one another and at least to some extent have been coupled to one another.

23. The process as claimed in claim 16, wherein the compression set of the damping body after 10% compression is <2%, measured in accordance with DIN ISO 815-1:2010-09.

24. The process as claimed in claim 16, wherein the damping tan δ exhibited by the damping body in the event of compressive or tensile deformation, in the direction of deformation, is from 0.05 to 2, measured in accordance with DIN 53535:1982-03.

25. The process as claimed in claim 16, wherein the 3D printing process is selected from melt layering, inkjet printing, photopolymer jetting, stereolithography, selective laser sintering, a digital-light-processing-based additive manufacturing system, continuous liquid interface production, selective laser melting, binder-jetting-based additive manufacturing, multijet-fusion-based additive manufacturing, a high-speed sintering process and laminated object modeling.

26. The process as claimed in claim 16, wherein the tensile modulus of the materials used for the damping body is <250 GPa, measured in accordance with DIN EN ISO 6892-1:2009-12.

27. The process as claimed in claim 16, wherein the spring element and the damping element are composed of different materials.

28. The process as claimed in claim 16, wherein the material of the spring element and of the damping element is selected mutually independently from metals, plastics and composites, in particular from thermoplastically processable plastics formulations based on polyamides, polyurethanes, polyesters, polyimides, polyetherketones, polycarbonates, polyacrylates, polyolefins, polyvinyl chloride, polyoxymethylene and/or crosslinked materials based on polyepoxides, polyurethanes, polysilicones, polyacrylates, polyesters, and also their mixtures and copolymers.

29. A viscoelastic damping body produced by a process as claimed in claim 16, where the damping body is configured as perforated hollow volume body, or its damping element is configured as perforated hollow volume body, where the perforated hollow volume body in particular has one or more of the following properties: hollow volume: from 1 μL to 1 L, preferably from 10 μL to 100 mL thickness of the material: from 10 μm to 1 cm, preferably from 50 μm to 0.5 cm diameter of the open passages: from 10 to 5000 μm number of pores/cm.sup.2 of external surface: from 0.01 to 100 area of pores/cm.sup.2 of external surface: from 0.1 to 10 mm.sup.2 modulus of elasticity in accordance with DIN EN ISO 604: 2003-12 of the material used: <2 GPa, in particular from 1 to 1000 MPa, preferably from 2 to 500 MPa.

30. A volume body comprising or consisting of a large number of damping bodies as claimed in claim 29, where the volume body in particular is a mattress.

Description

[0087] The invention is explained in more detail below with reference to examples and FIGS. 1 to 7, 8a to 8c, and also 9a to 9c, where

[0088] FIG. 1 shows a first example of a damping body of the invention and deformation thereof along a spatial axis,

[0089] FIG. 2 shows a second example of a damping body of the invention and deformation thereof along a spatial axis,

[0090] FIG. 3 shows a third example of a damping body of the invention and deformation thereof along a spatial axis,

[0091] FIG. 4 shows a fourth example of a damping body of the invention and deformation thereof along a spatial axis,

[0092] FIG. 5 shows a fifth example of a damping body of the invention and deformation thereof along a spatial axis,

[0093] FIG. 6 shows a sixth example of a damping body of the invention and deformation thereof along two spatial axes,

[0094] FIG. 7 shows a seventh example of a damping body of the invention and deformation thereof along two spatial axes,

[0095] FIG. 8a shows an eighth example of a damping body of the invention in three-dimensional view from above at an angle,

[0096] FIG. 8b shows a plan view of the eighth example of the damping body of the invention from FIG. 8a,

[0097] FIG. 8c shows the eighth example of the damping body of the invention along a vertical section line A-A in FIG. 8b,

[0098] FIG. 9a shows a ninth example of a damping body of the invention in three-dimensional view from above at an angle,

[0099] FIG. 9b shows a plan view of the ninth example of the damping body of the invention from FIG. 9a, and

[0100] FIG. 9c shows the ninth example of the damping body of the invention along a vertical section line B-B in FIG. 9b.

[0101] FIG. 1 depicts a sectional side view of an embodiment of a damping body 1 of the invention. The damping body 1 has been produced by way of a 3D printing process and in this case takes the form of porous hollow volume body (phvb) configured with a hollow body 2 which has a large number of open passages 3 filled with a fluid, in this case ambient air. In this case, therefore, spring element and damping element have been realized in one coherent component.

[0102] In the central depiction of FIG. 1, the damping body 1 is subjected to a compressive stress along the Z-axis. In this case, the fluid present in the open passages 3 is to some extent expelled. Damping of the deformation velocity is thus achieved.

[0103] In the right-hand depiction of FIG. 1, the damping body 1 is subjected to a tensile stress along the Z-axis. In this case, ambient air is sucked into the open passages 3, and the tensile stress velocity is thus damped. Compression or decompression thus changes the shape of the phvb 1, and therefore changes the hollow volume within the phvb 1, and fluid is thus forced through the pores/channels out of or into the hollow volume body.

[0104] FIG. 2 depicts a further embodiment of a viscoelastic damping body of the invention. Here, there are a large number of damping bodies 1 as in FIG. 1 coupled in alternation with spring elements 4 in the form of helical springs in z-direction, and arranged between an upper and a lower large-area structure 5. The large-area structures 5 can by way of example be rigid sheets, or else resilient sheets—for example a textile. For a use in applications with decompression of the damping body, the helical springs 4 and phvbs 1 adjacent to the large-area structure 5 must have been bonded to the respective large-area structures 5. In the case of this embodiment, the spring action of the damping body 1 in z-direction is amplified by the additional helical springs 4, while the damping provided by the entire arrangement is in essence defined via the damping behavior of the damping body 1. The large-area structures 5 can provide load distribution.

[0105] FIG. 3 shows a further embodiment of a damping body of the invention, analogous to FIG. 2. Unlike in FIG. 2, a jacket 6 completely encloses the large number of damping bodies 1 and helical springs 4. This type of embodiment can by way of example be used as mattress. The jacket 6 consists of a resilient material which ensures that the volume contraction due to pressure on at least one surface and resultant length decrease in at least one spatial direction of the three-dimensional structure can be compensated by a length increase in at least one other spatial direction. For a use in applications with decompression of the damping body, the helical springs 4 and phvbs 1 adjacent to the jacket 6 must have been bonded to the jacket 6 at least in the main direction of the decompression.

[0106] FIG. 4 shows a further embodiment of a damping body of the invention. Here, there are perforated hollow bodies 1 coupled in alternation with helical springs 4, and arranged on spatial axes running perpendicularly to one another. This type of damping body accordingly exhibits viscoelastic behavior at least in the direction of these two spatial axes.

[0107] FIG. 5 depicts a further embodiment of a damping body of the invention. The arrangement here has helical springs 4 and perforated hollow volume bodies 1 in asymmetrical sequence between a lower enclosing element 7 and an upper cover 8. In this embodiment, the left-hand region of the damping body in essence exhibits Hookean behavior, which toward the right-hand side changes to strongly viscoelastic damping behavior. The compression of this damping body is moreover limited by the exterior enclosing element 7 and the covering sheet 8, in that once the covering sheet 8 has come into contact with the upper edge of the enclosing element 7 no non-destructive further deformation of the damping body can occur.

[0108] FIG. 6 depicts a further embodiment of the damping body 1 of the invention, where perforated hollow bodies 1 of different size have been installed.

[0109] FIG. 7 depicts a further embodiment of the damping body 10 of the invention, produced by way of a 3D printing process. The damping body 10 has been realized in this case in the form of a folding bellows with an external wall 11 that, in sectional side view along the longitudinal axis, has alternating narrowed regions 12 and protruding regions 13. The damping body 10 moreover has open passages 14 through which the fluid present in the cavity 15 of the damping body, in this case ambient air, can flow out on compression of the damping body 10 along its longitudinal axis and, respectively, in turn can flow in during expansion.

[0110] The damping behavior of the damping body 10 can be adjusted via selection of the size of the open passages 14 and/or selection of the fluid present in the cavity 15 and, respectively, viscosity of the latter. In the case of this embodiment, the concertina-like configuration of the external wall 11 acts as spring element 4.

[0111] FIGS. 8a to 8c depict a further embodiment of a damping body 20 of the invention in an isometric representation of the three dimensions (FIG. 8a), in plan view (FIG. 8b), and also in sectional side view along the line A-A. The damping body 20 was produced by way of a 3D printing process, and consists of a cylinder 21 which is open at a flat end and in which there is a dome-shaped first chamber 23 positioned by way of retaining fillets 22. The first chamber 23 has a fluid-filled cavity 24 in the interior thereof and also, in the base region, has an open passage 25 through which the fluid can escape from the cavity 24 of the first chamber 23 into a second chamber 26 on exposure to compressive stress in z-direction. The first chamber 23 is moreover fixed in the cylinder 21 by a peripheral retaining ring 27 in which there are diametrically opposite outlet apertures 28 through which the fluid can escape from the second chamber 26 on exposure to compressive stress and, respectively, can flow back in during decompression.

[0112] When the volume of the dome-shaped first chamber 23 is reduced by compression, the fluid therein is forced into the associated second chamber 26. When by virtue of the recovery forces exerted by the material, the volume of the first chamber 23 is returned to its original size, the reduced pressure causes the fluid to flow back into the first chamber 23. The velocity at which the fluid flows out of and into the first chamber 23 is dependent on friction at the walls of the chamber 23, and in particular on the dimension of the open passage 25 and on the viscosity of the fluid. Fluids with different viscosity therefore give different moduli of elasticity and different damping properties of the damping body 20.

[0113] FIGS. 9a to 9c depict a further embodiment of a damping body 30 of the invention. FIG. 9a here shows the damping body 30 in an isometric representation of three dimensions, FIG. 9b shows the damping body 30 in plan view, and FIG. 9c shows the damping body 30 along a vertical section line B-B. The damping body 30 was produced by a 3D printing process, and comprises a cylinder 31 which is open at one end and in which there is a dome-shaped first chamber 32 fixed to the wall of the cylinder 31 by way of a retaining ring 33 arranged peripherally in the lower region of the first chamber 32. In the lower region of the first chamber 32 there is an open passage 34, through which a fluid in the cavity 35 of the first chamber 32 can flow out into a second chamber 36 when the damping body 30 experiences mechanical pressure along its vertical longitudinal axis. In the peripheral retaining ring 33, there are outlet apertures 37 through which the fluid can escape from the second chamber 36 when the damping body 30 is exposed to compressive stress.

Example of a Test Sample 1

[0114] A damping body 20 corresponding to the configuration shown in FIGS. 8a to 8c was used as test sample. A TPU with Shore hardness 85 A was selected as material for the damping body 20, and was 3D printed by means of FFF. Fluids used were air, a low-viscosity oil and a high-viscosity oil.

[0115] The diameter of the damping body (length of the line A-A) is 25 mm, the exterior radius of the dome-shaped first chamber 23 is 7.15 mm, the maximal vertical dimension of the cavity 24 is 9.4 mm and the diameter of the open passage 25, and also 28, is 2 mm. The wall thickness of the dome-shaped first chamber 23 is 0.6 mm.

[0116] The viscoelastic properties of the test sample were determined as follows:

[0117] The test sample was clamped in a Gabometer with axial compression resulting in compression to 80% of its original height. To this end, a ram with diameter 13 mm exerted pressure onto the first chamber (dome) of the sample. For the actual measurement, further pressure is applied to the test sample to induce sinusoidal, axial motion in the frequency range from 0.5 Hz to 20 Hz. The sinusoidal, axial motion is plotted against force. It is thus possible inter alia to derive the storage modulus and loss modulus G′ and G″. The quotient calculated from these is the loss factor, where tan δ=G″/G′. All of the measurements were made at room temperature and ambient pressure.

[0118] For all fluids used, a loss factor maximum was found at a frequency of 15.8 Hz. However, the magnitude of the loss factor varies considerably as follows:

tan δ (air)=0.31

tan δ (low-viscosity oil)=0.32

tan δ (high-viscosity oil)=0.38

Example of a Test Sample 2

[0119] A further damping body 20 was produced with geometry as in Example 1, but a TPU with Shore hardness 90 A was used as material for the test sample. All of the other conditions and test parameters are the same as in Example 1.

[0120] For all fluids used, a loss factor maximum was found at a frequency of 15.8 Hz. However, the magnitude of the loss factor varies considerably as follows:

tan δ (air)=0.31

tan δ (low-viscosity oil)=0.38

tan δ (high-viscosity oil)=0.50

[0121] In both inventive examples of a test sample 1 and 2, use of oils as fluid is found to give a higher level of damping in comparison with air as fluid. The higher-viscosity oil exhibits a greater tan δ increase than the low-viscosity oil, this being attributable to a higher level of friction in the walls of the damping body and in particular of the open passages. The hardness of the material used for the damping body also plays a part: when the oils were used as fluid, the damping values for the harder material (Shore 90 A, Example 1) are higher than for the softer material (Shore 85 A, Example 2). This is attributable to the higher compression modulus of the harder TPU grade.

LIST OF REFERENCE SIGNS

[0122] (1) Damping body or porous hollow body (phvb) [0123] (2) Hollow body [0124] (3) Open passage [0125] (4) Spring element or helical spring [0126] (5) Large-area structure [0127] (6) Jacket [0128] (7) Enclosing element [0129] (8) Cover [0130] (10) Damping body [0131] (11) External wall [0132] (12) Narrowed region [0133] (13) Projecting region [0134] (14) Open passage [0135] (15) Cavity [0136] (20) Damping element [0137] (21) Cylinder [0138] (22) Retaining fillet [0139] (23) First chamber [0140] (24) Cavity [0141] (25) Open passage [0142] (26) Second chamber [0143] (27) Peripheral retaining ring [0144] (28) Outlet aperture [0145] (30) (20) Damping element [0146] (31) Cylinder [0147] (32) First chamber [0148] (33) Peripheral retaining ring [0149] (34) Open passage [0150] (35) Cavity [0151] (36) Second chamber [0152] (37) Outlet aperture