DE102004047344A1 - Sound and vibration damping fiber reinforced supporting tube for magnetic resonance equipment comprises a fiber reinforced thermoset tube with elastomer film layer to isolate vibration transmission - Google Patents

Abstract

The tube(9) is molded in fiber reinforced thermosetting plastic(23) in which an elastomer film(11) is incorporated for damping of noise and sound transmission. Film(11) thickness is 0.5-2mm. Film softening point of the elastomer film is higher than the curing temperature of the thermosetting resin(23), preferably not less than100[deg]C, more preferably 135-145[deg]C. Mechanical damping is optimized by the film in the temperature and frequency range in which it is used. At least two reinforcing fiber layers(21A,21B) are included in the resin and one or more elastomer films located between them. Cut-outs(25) in the film form a flow path for the resin. The film may be arranged as bands around the tubular lining with space between them to form flow paths. The tube(9) forms a supporting tube for a hollow cylindrical magnetic resonance unit. Sound from a source of the MR equipment(1) outside the tube, e.g. a gradient coil unit(3), and mechanical vibration, is damped before reaching a patient area inside the tube. The supporting tube has a high frequency antennae unit for sending and receiving high frequency magnetic fields and/or a guide rail(13) for guiding a patient support(7) of the MR equipment. An independent claim is included for a process for manufacturing the tube in which: a) one or more layers of reinforcing fiber material(21A,21B) are laid onto a first tool part(31); b) an elastomer film(11) is laid onto the first fiber layer; c) fibers are impregnated with a resin and hardener mixture; d) the resin system is cured.

Description

The The invention relates to a molding made of a fiber-reinforced thermoset. Furthermore, the invention relates to a method for producing a such molding.

The Use of plastics to form moldings is far common. For example, in medical technology, glass-fiber-reinforced molded parts are used for the Interior paneling of magnetic resonance devices (MR devices) used. One possible high sound and vibration damping Effect of such a molding is just in such a Interior trim advantageous because outside of the interior lining pipe lying sound sources (gradient coils of the MR device) of Patient intake volume within the interior trim tube acoustically to be isolated.

elastomers are in contrast to thermosets elastically deformable plastics. you can deform under tensile and compressive load, but find it again afterwards back to their original form.

Usually becomes the oppression of vibrations of such moldings by stiffening of the molding causes. additionally or alternatively, such moldings are surrounded with foam.

thermosets are made of cross-linked macromolecules built up. When heated below the glass transition area they do not soften and melt, that is, they change their mechanical properties over one wide temperature range only slightly.

plastics be through their glass transition area (Softening range) defined; the glass transition area is the temperature range, in which the decrease in rigidity and the increase in ductility with higher Temperature disproportionately increase. He represents the transition from the glass to the rubbery state.

Fiber reinforcement plastics are also referred to as fiber composite material and consist of a Matrix material (e.g., epoxy resin as matrix) and embedded therein Fiber material (e.g., woven, scrim or roving of glass, carbon or plastic fibers). To take advantage of the stiffening properties of the fiber material can, they are embedded in the matrix. For the formation of molded parts becomes common a layer structure, i. several layers of fiber material one above the other, used.

For the production of such moldings, various manufacturing methods are known. In addition to the time-consuming hand lay-up method, for example, a so-called wet winding method or a (vacuum) casting method are used industrially. For example, in DE 102 19 767 A1 the production of an inner lining for a magnetic resonance apparatus by means of vacuum die casting method described. In the wet winding process, for example, pipes (eg the MR inner lining) are made of glass fiber reinforced plastic. To this end, resin-impregnated fiber rovings are wound onto a mandrel at a defined angle. Inner linings, which for example additionally comprise high-frequency antenna elements, are also produced in a closed mold by means of vacuum casting from a filler-containing casting resin using glass cloths / fabrics.

Out EP 0 323 612 B1 For example, a purely thermoplastic composite having an intermediate layer of a copolymer is known. The copolymer comprises "hard" blocks which combine with the resin of the thermoplastic, as well as "soft" blocks whose softening range is at a temperature below 25 ° C and which do not combine with the resin.

Out WO 2004/009924 A1 discloses a composite material which is acoustically or mechanically damped. It includes a variety of layers of fibrous material in one embedded solid material. The solid material has a composition, the above the thickness of the material varies. It is made of epoxy or Polyester resin as a first material and polyurethane as a second material together. The composition has one not abrupt change of the two materials. Furthermore is located in each layer of fiber material, mostly either the first or second fiber material.

task The invention is a molded part and a method for producing specify such a molding, wherein the molded part sound, which is generated on one side of the molding, sound-absorbing transferred the other side of the molding should, or dampens vibrations, the above mechanical contact e.g. above the storage be coupled.

• – Eine oder mehrere Lagen Fasermaterial in einer Matrix,
• – eine Lage Elastomerfolie,
• – Matrix mit eventuell einer oder mehreren Lagen Fasermaterial.

The object with respect to the above-mentioned molded part is achieved in that an elastomeric foil for sound / vibration damping is incorporated in the fiber-reinforced thermosetting plastic. The molded part according to the invention thus consists of the following layers:

• - One or more layers of fiber material in one Matrix,
• A layer of elastomeric film,
• - Matrix with possibly one or more layers of fiber material.

When Fiber material is used e.g. a fabric, scrim or roving made of glass, Carbon and / or plastic fibers.

Of the Layer structure according to the invention has the advantage of being muffling on acoustic vibrations acting on a first side of the molding be generated. The acoustic vibrations only lead to an excitation the first side of the molding, because the other side of the molding due to the interposed elastomeric film of the vibrations of the first Site is at least partially (vibration) isolated. The advantage the improved damping behavior leads to a significantly reduced volume on the other side of the molding. Another advantage is the cost-effective production by use commercially available materials and a simple production and arrangement of the individual layers.

The Task, based on the method for producing such Molding, is solved by that a first mold element is provided, at least one first layer of fiber material is placed on this mold element, an elastomeric film is placed on the first layer of fiber material, possibly a second layer of fiber material on the elastomeric film is arranged, the fiber material with a resin-hardener mixture waterproof becomes and becomes a fiber reinforced Thermosets is hardened with embedded elastomer foil. An advantage of the method is that the elastomeric film as a film simply placed between the two layers of fiber material can be. Since the film itself has no fiber material fits They adapt easily to the appropriate form. Another advantage lies in the fact that the elastomeric film already in the "cured state" is present, so that only the curing of the resin hardener mixture must be made.

Preferably is a softening range of the elastomeric film above a curing temperature of thermosets. This has the advantage that the elastomeric film during the curing process of the thermoset is retained as a closed layer. Preferably the softening range is above a temperature of 100 ° C.

A typical embodiment the elastomeric film is a thermoplastic polyurethane. A special embodiment the thermoset is a cured one Polyurethane, polyester or epoxy resin. Epoxy resin and an acid anhydride hardener have become as advantageous in use with an elastomeric film of thermoplastic Polyurethane proven.

Preferably the elastomeric film has a high mechanical damping in the relevant service temperature and use frequency range. The thickness of the elastomeric film is preferably of the order of magnitude from 0.5 mm to 2 mm. Such thick elastomeric films lead, for example at a thickness of the molding of 10 mm to a sufficiently rigid Molding that the desired Sound / vibration damping properties having.

In a particularly advantageous embodiment, the elastomeric film at least one recess, which provides a flow path for the not yet cured resin forms. This has the advantage that in a production of the molding in the casting process, a resin feed can only be done on one side of the molding and still one adequate impregnation the fiber material on the other side of the elastomeric film is possible. As an alternative to recesses, the elastomeric film may take the form of several At intervals spaced tracks embedded in the thermosetting plastic become. A cast resin compound the two layers of the fiber-reinforced Thermosets up to an order of magnitude of 10% of a maximum possible Expansion of the elastomeric film does not significantly counteract the sound / vibration damping.

In a particular embodiment of the molded part, this is designed as a support tube of a hollow cylindrical magnetic resonance apparatus. The support tube is formed, for example, as an inner lining of the magnetic resonance apparatus. It is thus between the main sound source of the magnetic resonance device (the Gradientenspulen) and the patient intake volume within the Support tube. The aim of the formation of the support tube as a molded part of a fiber-reinforced thermosets with an embedded elastomeric foil is the sound attenuation, i.e. the protection of the patient from the noise of the gradient coils.

In a particularly advantageous embodiment, the molding a plurality of layers of elastomeric foil arranged between each thermoset on.

This has the advantage that the sound-absorbing effect of the elastomeric film is used several times.

In an advantageous embodiment of the method, the first mold element is formed as a mandrel on which a glass fiber fabric and / or a glass fiber and / or a Glasfaserroving is wound. The fiber material may preferably according to the wet winding method before be impregnated.

In an alternative embodiment the first molded part with a second molded part becomes a liquid-tight Form supplemented, under vacuum with a casting resin hardener mixture is poured out. In the case of the support tube of an MR device that is first molded part, for example, formed as a metal mandrel, on the in a first step, the fiber material is wound, then the layer of elastomeric film is applied and then eventually wound up a second layer of the fiber material. After that, the Metal mandrel by placing several shell segments to one liquid-tight Mold closed. The resulting cavity is preferably under vacuum with a casting resin poured out. As a result, the fabric layers are impregnated. The whole shape will heated and the casting resin cured in this way. The cured one Cast resin forms both the desired Indoor as well the outer contour of the pipe.

In a particular embodiment becomes the saturation the fabric layers between the mandrel of the casting mold and the elastomeric film ensure a flow path for the Cast resin provided. The flow path can either through recesses of the elastomeric film and / or along from additionally wound up plastic cords run. The plastic cord between mandrel and fiber material wound up so that there are intersections, the one defined distance between mandrel and the first layer of fiber material generate, so that the casting resin reliable can get to all places.

Further advantageous embodiments The invention are characterized by the features of the subclaims.

The following is the explanation of several embodiments of the invention with reference to FIG 1 to 5 , Show it:

1 a schematic section through a magnetic resonance device,

2 an inventively constructed support tube of the MR device 1 .

3 a mandrel of a vacuum mold for a support tube after 2 with a first layer of wound fiber fabric and with two sheets of an elastomeric film,

4 a section through an open Vakuumvergussform and

5 the thorn out 3 with a partially wound plastic cord and with a wound layer of fiber material to ensure adequate impregnation of the fiber material.

As mentioned in the beginning, can the layer structure of the invention and the manufacturing process advantageous in the production of three-dimensional trim parts with optimized vibration behavior be applied. In Vakuumvergussverfahren be here to a half the Vergussform introduced the tissue and film layers, the casting mold subsequently closed and final with a casting resin potted, impregnated and hardened. In comparison with a thermoplastic, the production of a thermoset has the advantage that the casting resin due to its viscosity (even with fillers) despite the elastomeric film, the fabric material into a homogeneous matrix integrates. As a result, the production of a process technology inventive molding simplified.

alternative can the layer structure of the invention are prepared by wet winding, e.g. for optimization the vibration behavior of fiber reinforced pipes. This resin-impregnated fiber rovings wound on a mandrel at a defined angle. At a desired layer thickness The wrapping is done with a layer of elastomeric film and then the further winding of the resin-impregnated Fiber rovings. After application of the layer structure, the liquid resin is through temperature increase hardened. At the same time, the mechanical connection to the elastomeric film takes place.

When (Casting) resin a polyurethane, polyester or epoxy resin may be used. Preferred is an epoxy resin which is cured with an acid anhydride. The resin is selected such that the glass transition temperature of the cured molding material over the maximum operating temperature is. Preferably, the casting resin about 65% by weight of quartz flour as filler added. Depending on the fineness of the quartz flour, the use is recommended from coarse-meshed glass to a full saturation enable.

The Elastomer film should satisfy the following requirements: It should have a high mechanical damping in the relevant service temperature and Use frequency range. Furthermore, their softening temperature range should be above the for the curing of the resin hardener mixture required process temperature are.

Preferably, the elastomeric film and the casting resin are coordinated so that a good adhesion of the casting resin is achieved on the film. A favorable combination is a film of a thermoplastic polyurethane and a casting resin based on epoxy resin / acid anhydride. With a wall thickness of 10 mm, a preferred thickness of the elastomeric film is between 0.5 and 2 mm.

to additional Optimization of the damping behavior it is also possible the layered application of resin-impregnated fiber rovings and elastomeric film repeat several times.

1 refers to a known problem with MR devices 1 : the noise caused by vibrations of the gradient coil 3 that are caused by Lorentz forces. For powerful gradient coils 3 Very high noise levels are reached, in front of which a patient must be protected, who is in a receiving volume 5 of the MR device 1 on a patient couch 7 for medical imaging. Here comes an interior lining 9 a central importance because they are between the gradient coils 3 and the recording volume 5 is arranged. Preferably, the components of the MR device 1 constructed as possible in fiber-reinforced composite construction, so that no interaction with the magnetic field of the basic field magnet 15 takes place. The interior lining 9 is according to the invention of a fiber-reinforced thermosets with an embedded elastomeric film 11 built up. The interior lining 9 Further, for example, as a support tube for a high-frequency antenna of the MR device 1 be educated. Furthermore, the interior trim 11 additional guide rails 13 for guiding the patient bed 7 exhibit.

2 shows schematically the tube formed as inner lining 9 out 1 , It can be seen dashed the running inside the elastomeric film 11 , In the cutting plane are the layers of the fiber material 21A . 21B indicated in the matrix 23 are poured. Furthermore, one recognizes recesses 25 in the elastomeric film 11 , The recesses allow impregnation of the fiber material on both sides of the elastomeric film 11 , The length of the interior lining 9 is about 90 cm, her diameter, for example, 70 cm. The diameter of the recesses 25 is about 5 cm.

3 shows a thorn 31 as the first mold element for the production of the interior lining pipe 9 out 2 is being used. On the thorn 31 is the first fabric layer 21A for example, by wet winding, which over the entire length of the mandrel 31 runs. On the first fabric layer 21A were alternative to realization in 2 two bands 33 wound up an elastomeric film. The released area 35 allows a soak on the spine 31 resting first tissue layer 21A , In addition, the bands could 33 Recesses, accordingly 2 , exhibit. The uncovered area of the first fabric layer can occupy up to approximately 10% of the area of the first fabric layer, without the sound-damping effect being significantly impaired.

4 illustrates the method according to the invention by way of example on a quadrant of a liquid-tight mold 41 that the thorn 31 as the first form element and a hollow cylindrical shell element 43 includes. Within the form 41 you can recognize the first fabric layer 21A as well as the second fabric layer 21B and the between the two fabric layers 21A and 21B arranged elastomeric film 11 with the recesses 25 , The vacuum mold has an inflow 45 through, by a resin-hardener mixture in the casting mold 41 can be introduced. In 4 is a mold cover not shown, which additionally has an overflow container. Alternatively, only one layer of fabric may be on one side of the elastomeric film 11 to be ordered. To balance the stability, the side can be made slightly thicker without tissue support. For example, in 4 the fabric layer 21B Not used.

For casting, first two components which form the thermoset, a resin component and a hardener component, are mixed separately with particulate fillers and the two mixtures obtained are homogenized and degassed with stirring and vacuum and optionally at elevated temperature. Subsequently, the two mixtures are mixed in the correct ratio, preferably under vacuum to a pourable mass. The mixing of the two mixtures can take place in a continuous process via a static mixer or in discontinuous batch operation. The liquid-tight form 41 is preferably potted with the pourable resin-hardener mixture under vacuum. In this case, a Vergusstemperatur depending on a fluidity of the mass is about 20 to 80 ° C. The curing of the mass to the fiber-reinforced thermoset occurs depending on the reactivity of the mass in a temperature range that starts at room temperature and reaches up to about 120 ° C, but remains below the softening temperature of the elastomeric film. When casting the mold 41 the resin-hardener mixture passes through the recesses 25 to the inner fabric layer 21A ,

5 illustrates an alternative approach to the impregnation of the inner fabric layer 21A between the thorn 31 the casting mold 41 and the elastomeric film 11 sure. A defined flow path for the resin-hardener mixture at the mandrel 31 along is produced as follows: A, for example, 0.5 to 1.0 mm thick plastic cord 51 is wound up in several layers. By the line 51 and the intersections 53 becomes a defined distance between mandrel 31 and the inner fabric layer 21A adjusted, over which the casting resin reliably to all points of the inner fabric layer 21A can flow.

Claims (25)

Molded part ( 9 ) made of a fiber-reinforced thermoset ( 23 ), wherein an elastomeric foil ( 11 ) for sound and vibration damping in thermoset ( 23 ) is stored. Molded part ( 9 ) according to claim 1, wherein a softening region of the elastomeric film ( 11 ) above a curing temperature of the thermoset ( 23 ) lies. Molded part ( 9 ) according to claim 2, wherein the softening range above a temperature of 100 ° C and in particular in the temperature range between 135 ° C and 145 ° C. Molded part ( 9 ) according to any one of the preceding claims, wherein the elastomeric film ( 11 ) consists of a thermoplastic polyurethane. Molded part ( 9 ) according to any one of the preceding claims, wherein the elastomeric film ( 11 ) has a high mechanical damping in the relevant Einsatztemperatur- and / or Einsatzfrequenzbereich. Molded part ( 9 ) according to any one of the preceding claims, wherein the elastomeric film ( 11 ) has a thickness between 0.5 mm and 2 mm. Molded part ( 9 ) according to any one of the preceding claims, wherein the thermoset ( 23 ) consists of a polyurethane, polyester or epoxy resin, preferably from an acid anhydride cured epoxy resin. Molded part ( 9 ) according to any one of the preceding claims, wherein the thermoset ( 23 ) has a filler, in particular of quartz powder. Molded part ( 9 ) according to one of the preceding claims, wherein the fiber-reinforced thermoset ( 23 ) at least two layers of a fiber material ( 21A . 21B ), between which the elastomeric film ( 11 ), wherein the fiber material ( 21A . 21B ) in particular has a fibrous tissue and / or -gelege and / or -roving. Molded part ( 9 ) according to any one of the preceding claims, wherein the elastomeric film ( 11 ) at least one recess ( 25 ), which forms a flow path of the not yet cured casting resin. Molded part ( 9 ) according to any one of the preceding claims, wherein the elastomeric film ( 11 ) a plurality of side by side spaced tracks ( 33 ). Molded part ( 9 ) according to any one of the preceding claims, wherein the sound damping by one of the elastomeric film ( 11 ) caused acoustic decoupling of the elastomeric film ( 11 ) adjacent sides of the thermoset ( 23 ) given is. Molded part ( 9 ) according to one of the preceding claims, wherein the molded part ( 9 ) as a support tube of a hollow cylindrical magnetic resonance apparatus ( 1 ) is formed and wherein sound is arranged outside the support tube sound source of the magnetic resonance apparatus ( 1 ), in particular a gradient coil unit ( 3 ), to a within the support tube arranged patient receiving area ( 5 ) of the magnetic resonance apparatus ( 1 ) is transmitted attenuated, and are attenuated via a mechanical contact coupled vibrations. Molded part ( 9 ) according to claim 13, wherein the support tube is a high-frequency antenna unit for transmitting / receiving high-frequency magnetic fields and / or a guide rail (16). 13 ) for guiding a patient couch ( 7 ) of the magnetic resonance apparatus ( 1 ) having. Molded part ( 9 ) according to one of the preceding claims, wherein the molded part ( 9 ) several each between thermoset ( 23 ) arranged layers of elastomeric film ( 11 ) having. Method for producing a molded part ( 9 ) having the following process features: a) providing a first formula element ( 31 b) arranging at least one first layer of fibrous material ( 21A ) on the first mold element, c) applying an elastomeric film ( 11 ) on the first layer of fiber material ( 21A ), d) impregnating the fiber material ( 21B ) with a resin-hardener mixture, e) curing the resin-hardener mixture to give a fiber-reinforced thermoset ( 23 ) with embedded elastomer foil ( 11 ). The method of claim 16, wherein after laying the elastomeric film ( 11 ) a second layer of fiber material ( 21B ) on the elastomeric film ( 11 ) is arranged. Method according to claim 16 or 17, wherein the first shaped element ( 31 ) is formed as a mandrel and being as fiber material ( 21A . 21B ) a fiber fabric and / or a fiber fabric and / or a Faserroving is wound on the mandrel. Method according to one of claims 16 to 18, wherein the fiber material ( 21A . 21B ) is pre-impregnated, ie, the impregnation takes place at least partially prior to arranging the layers of fiber material. Method according to one of claims 16 to 19, wherein a closed mold ( 41 ) by attaching a second formula element ( 43 ) on the first mold element ( 31 ) is formed and is poured with a casting resin-hardener mixture. The method of claim 20, wherein supplying the resin-hardener mixture on one side of the elastomeric film ( 11 ) and a saturation of the on the other side of the Alastomerfolie ( 11 ) arranged fiber material ( 21A ) by flowing the resin-hardener mixture through at least one recess ( 25 ) in the elastomeric film ( 11 ) respectively. A method according to claim 20 or 21, wherein the closed mold ( 41 ) with an inflow ( 45 ) and overflow is provided and the pouring takes place in Vakuumvergussverfahren. Method according to one of claims 16 to 22, wherein additionally a string ( 51 ) between mandrel and fiber material ( 21A . 21B ) is arranged so that adjusts a distance between the mandrel and the fiber material in the region of the cord, which allows an inflow of the resin-hardener mixture and to a uniform impregnation of the fiber material ( 21A ) leads. Method according to one of claims 16 to 23, wherein the thickness of the elastomeric film ( 11 ) is optimized such that at a total rigidity of the molded part ( 9 ) the vibration transmission through the elastomeric film ( 11 ) is minimized. A method according to any one of claims 16 to 24, wherein the impregnation preferably with a filler-containing Resin / hardener mixture if necessary increased Temperature takes place.