5 The present invention relates to an article consisting of metal or plastic which exhibits means for reducing the occurrence of frame noise in the article in question, and applied to the surface of said article is a material which, in its effective state, exhibits a high modulus of elasticity, in the form of a number of beads and/or patterns intended to function as vibration dampers.

Frame noise in articles consisting of metal or plastic material is normally reduced by a layer of means appropriate for the purpose, either as an extruded or as a painted coating of an appropriate damping material, or by gluing mats of sound-damping material, or attaching them in some other way, over the whole of the articles that are subject to vibrations. This gives rise to a number of disadvantages, for which there has been the wished to find various sollutions.

The principal object of the present invention is thus, in the first instance, to attempt by simple and effectively functioning means to solve earlier problems with frame noise in articles of the indicated kind. Said object is achieved by means of articles and means in accordance with the present invention, which is characterized essentially in that said applied damping material is of a highly viscous type or has the ability to harden or set after having been applied, in that the damping material is preferably applied to the article at high pressure by extrudeing or is applied to the article in some other way, and in that the damping material is applied from outside the investigated vibration characteristic of the article.

Methods of attempting to damp frame noise in articles consisting of metal or plastic have involved causin the whole of the intended surface of the article where it is wished to achieve noise damping to be covered with appropriate damping material, for example by extrudeing or painting on a liquid material or gluing sheets of damping material in position. Amongst other things, this has consumed large quantities of material, has involved the emission of undesired substances into the atmosphere and has meant a poor working environment for those performing the work, in addition to which it has been difficult to cover the entire surface and to cause the material to adhere, so that automation has been made more difficult, and has involved the holding of large stocks of material. A further object of the invention is thus to identify a method which, amongst other things, solves the above-mentioned problems.

Said further object is achieved by means of a method in accordance with the present invention, which is characterized essentially in that a highly viscous or setting material, which exhibits the ability to harden or set through another reaction to an extent specific to the article, is applied, in that said damping material is preferably applied at high pressure or in some other way and with high accuracy in the form of only a number of beads and/or an intended pattern to the article in question, and in that damping material is applied from outside the investigated vibration characteristic of the article, for example in accordance with accelerometer measurement, stroboscopic measurement or with experimental modal analysis.

Arrangements for effecting application of frame noise damping material to articles which consist of metal or plastic material have included air-operated extrusion systems or brushes for damping material, or application devices for the adhesive for damping mats.

A final object of the invention is thus to make available an arrangement which solves the problem of effective application, with the associated possibility of automation, of damping material to the articles in question. Said final objective is achieved by means of an arrangement in accordance with the present invention, which is characterized essentially in that a material- accommodating container is connected to a membrane activated with hydraulic fluid, and in that a heating zone for the damping material is arranged in conjunction with an applicator nozzle.

The invention is described below with reference to the accompanying drawings, in which

Fig. 1 shows a sectioned view of an arrangement for the application of damping material.

Figs. 2-4 shows different patterns of the applied damping material on sheet articles.

Fig. 5 shows a sectioned view of a first example of damping material applied to an article, and Fig. 6 shows a sectioned view of a second example of damping material applied to an article.

Articles 1 made of metal or plastic material, such as vehicle components, for example doors which are subject to movement, vibrations and forces, etc., such that frame noise occurs in the articles in question, exhibit means 2 for reducing the occurrence of frame noise in the article 1 in question. Applied in accordance with the present invention over a limited part of the surface 3 of said article 1 is a material 2 which, in its effective damping state, exhibits a high modulus of elasticity (E) in the form of a number of beads 4 and/or in the form of a desired pattern 5, thereby functioning as a vibration damper for the article 1 in question.

The applied frame noise damping material is preferably of a highly viscous type, such as a fluid. It may

contain heavy filling materials 6, such as metal fibres, or may be made from expandable foam material which exhibits a skin 7 or open pores 8.

Two different materials 2 ¹ , 2 ² may be applied to the article, for example, namely one hard reinforcing material 2 ¹ as the inner base on the article 1, and applied on top of it a softer material 2 ² which exhibits an absorbent surface 2 ² A.

Said applied sound damping material 2 is adapted if it is a single material, and are adapted if the number of materials involved is more than one, having regard for the noise, and is applied in the form of beads 4 or in a pattern 5, which is adapted in such a way that sound damping is achieved in conjunction with a change to the vibration pattern and absorption of the article in question.

The material 2 consists preferably of an appropriate number of material groups: hardening materials, plastic materials, vulcanizing materials and thermoplastic materials. The applied material 2 is applied in the form of beads 4 and/or with a pattern 5 adapted to the article 1 in question for the reinforcement and modification of the vibration frequency of the article in combination with the absorption of noise. Said damping material 2 already has a high modulus of elasticity at the time of application, or achieves a high modulus of elasticity after extruding on the material 2, and, once the material has adhered to and set on the surface 3 of the article, acts as a vibration damper for the article 1.

The damping material 2 may be fluid by nature or may be made fluid by the application of heat, or may be prepared in some other appropriate way for application at high pressure and rapid hardening of its own accord on the surface 3 to which the material 2 is applied.

A method intended for the invention for the manufacture of an article 1 in accordance with the present invention involves causing a material 2 to be extruded or applied in some other way, which material possesses or, after the application in question, assumes a high modulus of elasticity. The material 2 is applied in the form of a number of beads 4 and/or a pattern 5 to the article 1 in question over at least one surface 3. The applied material 2 thus adheres of its own accord and functions as a vibration damper for the article 1 in question. The damping function of the article 1 in question is thus preferably optimized in relation to the quantity of damping material 2 applied, which is achieved by applying to the respective article 1 a damping material 2 with unique surface covering properties for the article 1 in question. Said damping material 2 is best applied at high pressure to the surface 3 of the article, and with high accuracy, in the form of only a number (one, two or more) of beads 4 and/or with an intended specified pattern to the article 1 over a limited part of said surface 3 of the article 1 in question.

Preferably a highly viscous or setting material 2 is applied, which exhibits the capacity to harden, or which is able to set through some other previously disclosed reaction for the material 2 in question, to an extent specific to the article 1. Damping material 2 is applied from outside the investigated vibration characteristic of the article in accordance with accelerometer measurement, stroboscopic measurement or with experimental modal analysis. "Damping materials 2 of different kinds are preferably applied in conjunction with this, namely a first hard reinforcing material 2 ¹ as the base, and a second softer material 2 ² applied thereon as an outer layer, which exhibits an absorbent surface 7 on the outside.

WO 96/23988 -«-.,-.--

PCT/SE96/00106

Aids for applying such damping material 2 to articles which consist of metal or plastic for the purpose of reducing the occurrence of frame noise in the article in question comprise an arrangement 9 having a material accommodating container 10 connected to a membrane 12 activated with hydraulic fluid 11, which is preferably formed from a chamber accommodated internally within the container 10 consisting of a flexible material such as rubber. The arrangement 9 also has a nozzle 14, which is attached to the container 10 via a channel 15, for example an extrusion tube which leads from an outlet 16 in the container 10. A heating zone 17 for heating the material 2 as it is extrudeed is provided in the arrangement 9 in conjunction with said application nozzle 14 close to its outlet 18 for damping material 2, which it is intended to extrude onto the adjacent article 1, for example a car door, a white goods article or a piece of sheet metal, etc., in an efficient and environmentally safe fashion. Said heating zone 17 may be of a similar kind to that found in an injection nozzle in plastic injection machines used in the plastic manufacturing industry, i.e. a heating coil 19, for example, which, when activated electrically, melts the material 2 as it is extruded, which material is forced rapidly from the container 10 with the help of the membrane 12 activated by hydraulic fluid 11 via the outlet 18 and onto the intended article 1 as a bead 4 or in a pattern 5 of a specific kind in accordance with the invention at a small distance 20 from the article 1 in question.

A preferably electromagnetic valve 21 is arranged at the mouth 22 of the chamber and is controlled via an electrical circuit 24 in the container 10. There is also an inlet opening 23 for hydraulic fluid 11 from a pressure vessel (not shown) . The pressure inside the chamber 7 can be regulated with the valve between working pressure and zero pressure. In conjunction with this the membrane will activate

the material inside the chamber and force it out through the heating zone and out through the nozzle.

The arrangement 9 is suitable, with the use of high pressure close to the nozzle 14 and with the application of heat in the nozzle, for applying highly viscous material for purposes other than sound damping. Through the combination of high pressure and high viscosity, said valve in the nozzle can also be eliminated with unimpaired accuracy with regard to the quantity of material intended to be applied to a surface and in respect of "stopping and starting" the arrangement.

The invention thus offers the following advantages, amongst others:

A) Reduced material consumption B) Reduced level of emissions in the hardening process

C) Reduced material stock levels

D) Facilitates automation of the process

E) More rapid process

F) Improved working environment, including from automation

G) Permits application at inaccessible points

H) Simplifies the process by enabling noise-deadening measures to be implemented at an early stage in complex processes I) Extremely good adhesion is assured by applying the material at very high pressure

The invention is not restricted to illustrative embodiments described above and shown in the drawings, but may be varied within the scope of the Patent Claims without departing from the idea of invention.