WO2011038428A1

WO2011038428A1 - Method for producing loudspeaker housing elements and loudspeaker housings

Info

Publication number: WO2011038428A1
Application number: PCT/AT2010/000344
Authority: WO
Inventors: Karl Vorlicek
Original assignee: Karl Vorlicek
Priority date: 2009-10-01
Filing date: 2010-09-21
Publication date: 2011-04-07
Also published as: DE112010003896A5; AT508943B1; AT508943A4

Abstract

The invention relates to a method for producing loudspeaker housings and loudspeaker housing parts, characterized in that the loudspeaker housing parts are produced in a vacuum casting process or in a pressure gelation process (APG) preferably using anhydride-cured epoxy resins. In order to improve the sound insulation or to reduce the sound conduction, mineral fillers, such as quartz powder and soft fillers, or also hollow glass balls are used in combination. In order to avoid standing waves, the inner housing surfaces are arched or curved. The curvature of the inner surfaces to reduce standing waves has a wall thickness profile similar to a Gaussian curve so that the wall thickness increases in the direction of the housing interior - preferably toward the surface centers. Thus, the waves are irregularly scattered in the housing interior. Irregular housing shapes having arched and curved surfaces can thus be realized without machining.

Description

Method of making loudspeaker enclosure elements and loudspeaker enclosures

Loudspeakers are installed in housings for a variety of reasons. Thus, the closed housing serves to avoid the acoustic short circuit. Bass reflex or Bandpass housing are designed as a resonator, which specifically the transmission behavior can be optimized at low frequencies. However, the loudspeaker cabinet itself is also a source of error, which can lead to undesirable non-linearities in the transmission behavior and thus to distortions and distortions of sound. These are listed below.

The housing or the housing walls must have sufficient stability, otherwise parasitic bending vibrations on the housing components or housing walls can be excited.

The housing must provide sufficient insulation, so as not to adversely affect the acoustic efficiency - if the sound radiation is not due to the

provided sound openings occurs phase-shifted housing vibrations. Therefore, it is preferable for speaker casings

High density materials used, such as MDF boards or marble. (To avoid this impairment, housings are also constructed according to the sandwich principle, where sand is introduced between the inner and outer housing.)

Loudspeaker enclosures are usually executed in cuboid shape. Through opposite housing walls with equal intervals, standing in the interior of the housing standing waves, which lead to a non-linearity in the transmission behavior. Generally, cuboid housings have three interfering ones

Frequencies or housing resonances on, by the distances from bottom to top, from the distances of the side walls to each other and from front to

Rear wall are set. By arranging damping material inside the housing or by inner partitions, these sound waves are attenuated, but not avoided. By introducing partitions, this effect can be minimized, but as a rule, other frequencies arise due to stagnant waves.

Diffraction interferes with the sound of the front edges of the case.

The directional characteristic of loudspeakers without pre-set horns shows - especially at high frequencies - an unwanted bundling.

The montage of loudspeakers on a flat baffle generally leads to runtime differences between the individual loudspeakers, since the voice coils are not in one plane because of the different overall depths.

Many of the above-mentioned disadvantages have their origin in the housing structure with flat elements, these are usually wood fiber, MDF or chipboard. To avoid these characteristics, loudspeaker cabinets should preferably be made with irregular shape - preferably with curved and curved surfaces in order to avoid initially volumes with equal and parallel surface distances. However, this requires different manufacturing methods than those required for housing of sheet materials.

The proposal according to the invention describes preferred production methods and the execution of such produced. Speaker housing elements or speaker housing in industrial quantities. The housing elements are produced in a casting process from epoxy resins in combination with anhydride hardeners, fillers and additives. In contrast to polyurethanes or amine-curing epoxies can be realized with anhydrides Vergußgewichte to over 200kg, since the exothermic nature of the crosslinking of the active components can be controlled with appropriately heated molds. For small and medium volumes, the housing elements will be added after the automatic pressure gelation process

Gelling temperatures between 80 ° and 160 ° C made larger items

preferably gelled by the vacuum casting method at comparatively lower temperatures in the mold. After demolding, the parts are generally cured in a separate oven.

The reaction mass prepared from epoxy resin, anhydride hardener, filler and additives is preferably degassed before casting in the treatment plant. The potting itself is preferably also carried out under vacuum. As the molds polished

Having surfaces and the potting compound has been evacuated, and the casting process (vacuum casting) is preferably carried out under vacuum, components with high-gloss surfaces can be created. In the atmospheric pressure gelling process (ADG), the mold is filled on its underside (increasing encapsulation). The existing in the form of air is displaced during the filling process via vents from the potting compound - can be dispensed with the application of vacuum, for the highest

Here too, the mold is evacuated). In contrast to housing components, which are made of polyment or polymer concrete, in these methods is no

Reworking - such as puttying to close voids, air pockets and pores, and no sanding - is required to achieve the desired surface finish. By adding pigments, the desired color tone can be adjusted. With additives such as mica or metal particles, a shimmering surface can be achieved.

The reactive mass is composed of the following components (GT = parts by weight):

100 parts by weight of bisphenol A epoxy resin or bisphenol A / F epoxy resin preferably in the liquid phase having an epoxy content of 4 to 6 epoxy equivalents / kilogram or 100 parts by weight of epoxy solid resin having an epoxide number of 2 to 3 per kilogram.

100 GT of resin are used with 65-100 parts by weight of anhydride hardener of the type methyltetrahydrophthalic anhydride or methylhexahydrophthalic anhydride or a liquid

Hardener mixture consisting of about 30% Methylhexahydrophtalsäureanhydrid and 70% Hexahydrophtalsäureanhydrid mixed.

Of course, solid hardeners phthalic anhydride, hexahydrophthalic anhydride or tetrahydrophthalic acid amide can be used: these are added in an amount of 30-40 GT to 100 GT resin.

Flexibilizers such as polyethylene or polypropylene glycol are incorporated in amounts of about 20 pbw to 100 pbw of resin.

Toughening modifier is mixed in 0 to about 15GT to 100 GT resin.

If necessary, the mixture is adjusted with an accelerator for optimum process times - for example, 0 to 2.5 GT tertiary amine, about BDMA added to 100 GT resin .. Pigments or color powder such as carbon black or iron oxide, titanium oxide can, depending on color and color saturation up to 5 GT can be included in the mixture. Finally, filler is also added to the mixture. The total filler content of the mixture should exceed 55%, ideally between 57 and 75%. The

Difference amount to 100% consists of the above-described epoxy mixture.

The filler used is preferably quartz powder, but also chalk (with round or rod-shaped grain), or else aluminum oxide or aluminum trihydrate. Also

Rubber balls or gum can be used if the proportion reaches or exceeds at least the content of the epoxy resin / hardener mixture (This ratio, which is practically usable with epoxy mixtures with anhydride hardeners, at the same time results in a distinction from the document DE 3905562.)

For attractive surfaces, it is also possible to use color-quartz or color-quartz mixtures of different colors. This is a quartz that is colored.

Preferably, a mixture of at least two fillers will be used.

For example, quartz powder may be mixed with chalk with or gum, or colorite may be mixed with chalk. In the table the respective mixtures are listed. The ratio of the active components to the filler is shown by way of example in the first column.

Mixtures in parts by weight:

Preferred filler mixtures (ratio of the amounts of filler to one another in

parts by weight

CaCo3 chalk / 1 1 1 1

wollastonite

Coloring quartz 1 1

Alumiunium oxide 1

Rubber Crumb 1 1

Quartz flour 1

Aluminum trihydrate 0.3-1 0-1 0-1 0-1 0-1

Hollow balls after

Manufacturer Rec.

Aluminum trihydrate or magnesium trihydrate may be used as an anti-flaming filler alone, e.g. instead of quartz flour or as an additive. The different densities and degrees of hardness are shown below. Filler combinations with different hardnesses and densities have an acoustically particularly favorable effect and should therefore be used with preference.

The hollow spheres play a special role as fillers: these are available, for example, as hollow phenolic resin beads, hollow polyethylene beads or aluminum silicate hollow spheres. Preferably glass hollow spheres but also hollow metal spheres can be added to the active epoxy mixture alone or in combination with mineral fillers. With these hollow spheres, the density of the total mixture can be reduced by up to about 30%, which is advantageous for large-volume housings. Acoustically, the hollow spheres - especially in combination with mineral fillers - cause the reduction of the sound conduction at medium and higher frequencies and a reduction of the sound conduction

Resonance frequencies (where the insulation reaches a minimum). The densities of the hollow spheres and their hardness vary widely, due to the difference in the ball material and the difference in the enclosed cavity. Elastic hollow spheres are also characterized by particularly good sound attenuation - especially at medium frequencies - from.

density

Thus, a method is described, with which housing components of high mass can be produced with individual components of different densities. The usage of

Fillers of different densities minimize the passage of sound, because instead of a mass-dependent resonance frequency, a resonance saddle curve is generated with less pronounced Maximas. (In the case of sound transmission, these are, of course, minima of the intensity of the permeability or conductivity)). As a result, both sound transmission and cabinet resonances can be reduced and according to the previous explanations particularly advantageous rounded, curved surfaces can be realized, the no

4 require further surface finishing. (If desired, you can also varnish visible surfaces - this is preferably done with acrylic varnishes or polyurethane varnishes.) To increase the mechanical strength of the potting compound

Fiberglass chips are added. But it can also reinforcing fabric or

Reinforcing nets are inserted into the mold, made of carbon, glass, aramid or

Natural fibers exist.

Below are some inventive preferred embodiments of

Speaker elements are produced, which are produced by this method.

In Figure 1, based on AT 409910 a loudspeaker housing is shown, which has been described in this application. The proposed in AT 409910 embodiment of the front panel will now be used as an exemplary example. For example, this front panel can be milled and turned from solid material - but due to the layer thickness, it can not be injection-molded. With the ADG or Vakuumgußverfahren according to the inventive proposal, such a part can be produced without rework. Size

Housing elements can be additionally reinforced mechanically by fabric inserts, for example by nets, which are encapsulated. Mounting elements, such as

Threaded bushes for speaker attachment or for fastening the front panel to the other housing parts are fixed in the mold and surrounded. No further

Steps are necessary. The front panel could be screwed to a corpus made of chipboard or MDF panels and brings considerable advantages; amongst other things:

- Rounded front edges

- Sound conduction for one or more speakers

- Low resonance of the front panel

- Loss time difference minimization through optimized, approximately the same horizontal position of the voice coil.

For further optimization, according to the inventive proposal, a cast

Housing body presented. The outer body is shown for ease of illustration with flat surfaces, these are preferably performed curved in practice.

An essential feature can be seen from the pages after Fig. 2b: The inner sides of the side and bottom walls have variable wall thickness. (In Figure 2a, the flat wall of the wall with a curved inner surface of FIG. 2b is compared). Of the

Wall thickness gradient increases to the center approximately with the profile of a Gaussian bell curve. On the one hand bending vibrations are avoided, on the other hand, the formation of standing waves is minimized, since the spectrum is fanned out according to the different wall - distances (by reflection) and reduced in intensity. The proposal according to DE 4000132 has inside walls with pillow-shaped course and only slight bends, these elements are subsequently mounted on flat surfaces of a flat wooden housing, which is very cumbersome and costly. Furthermore, the large radii of curvature according to DE 4000132 have less sound-scattering effect than the proposal described here).

The reinforcements with the Gaussian curve profile, generally with a symmetrical wavy profile, which are preferably arranged approximately in the middle of the walls (half body depth), can also merge into one another so that walls lying opposite one another are connected to one another and a reinforcing plate is formed inside the body , The air volumes in front of and behind the reinforcement are given by decreasing heights of the Gaussian curve to the side and bottom and top elements, respectively. In addition, air outlets can also be created by appropriate drilling, for which the Form is to be executed with corresponding cores and Kernzügen. Figure 3a again shows the plate-shaped stiffening and schematically the stiffening with elements which have a gaussian curve-like cross section (Figure 3b). The rear wall is preferably reinforced as well. The connection is made by screwing or

Bonding with the body or the housing body is preferably with the

Reinforcing plate cast in one piece.

Another embodiment is shown in Figs. 4a and 4b:

According to this embodiment, the body can be made with back wall in one piece; Rear wall and side parts in turn have the reinforcements with Gaussian curve profile; in such a way that the rear wall and side parts are connected by these profiles cross-shaped. (The front reinforcement strut is not shown in the drawing for clarity.) The height of the profiles may be identical, but will preferably be different. In Figure 4b, the height of the bell curves to the center drops off, it can have the Gaussian profiles in particular pronounced height saddles, which find the voice coils of the speakers between their Höhenhöckern. The height drop is preferably realized rounded - in Figure 4b, the height increase was shown linear. The height of the Gaussian reinforcing profile begins approximately at the entire depth of the side parts and then falls saddle-shaped between the location of the voice coil of the

Bass speaker off, but you can also increase about in the middle of the back wall height again in height. Then she falls off again. Essential here too is an irregular one

Design of the Gaussian curve-shaped profile of importance that standing waves can not form and that irregular wall clearances are created - in addition to the mechanical reinforcement also follows a reduction in the bending vibrations. Since, according to FIG. 4b, several Gaussian curve profiles (perpendicular) meet, the sound waves inside the housing are particularly well distributed. The shape of the reinforcing profiles or the wall profile elements can be identical or different for several or all walls or elements. The ridge or the projection of the ridge of

Reinforcement profiles on the wall surface can also be made irregular, as shown in Figure 5, so that it does not come to rest parallel to the sides of the housing or housing edges. In Figure 5, an elliptical arc-shaped ridge is shown.

The course of the profile with variable height along a wall or a wall profile with variable height is shown in FIG.

The profile shape of the stiffeners or the housing walls can the mentioned

Gaussian curve profile, or it can the wall thickness towards the center with a

An essential feature is the creation of curved inner surfaces which are mechanically reinforcing and have good sound dispersion relative to the inner volume of the housing.

Further optimizations can be made by the shape of the body deviates from the cuboid shape. For example, the floor plan may be larger than the lid, or the rear wall and / or the side panels may be curved. The box can now be produced in the form of an ellipsoid, a paraboloid, in the form of a curved vase cut to one side or in the shape of a bass violin case or any other shape, without the expense of production increasing significantly, as long as undercuts are avoided.

An inclined against the vertical design with circular arc-shaped front and rear walls is shown in Figure 6. This production can be carried out efficiently only by means of molds and by means of corresponding closing machines, which receive the mold halves, when they are equipped with corresponding core pulls. The temperature control / heating of the molds must be carried out in such a way that the exothermicity is controlled during the crosslinking of the potting material. With cold-curing systems this is only possible up to a few kilograms of mass. This results in another inventive

Demarcation.

Likewise, there is a distinction from the RTM method: on the one hand, only a limited layer thickness of carbon or glass fiber can be impregnated in that, because the dense tissue opposes the injection resin with high resistance. On the other hand, the requirement for low viscosity of the injection resin prohibits the use of the filler-blended resin blends described herein which make the desired high density possible. Furthermore, any curved and curved shapes are very expensive to produce, since geometrically non-developable surfaces require the production of reinforcing fabrics from sewn together individual pieces.

Furthermore, the long cycle times and the high cost of this method differ from the proposal according to the invention, which enables the rational mass production of loudspeaker cabinets of high quality in industrial quantities.

Compared to loudspeaker casings, which are injection molded, extruded or injection molded, the demarcation is given that they can not be so highly filled with mineral and, above all, that the wall thicknesses must be uniform and limited to layer thicknesses of mm range, which is not in sufficient insulation expresses.

Claims

Claims:

1. A method for producing loudspeaker enclosures and loudspeaker housing parts, characterized in that the loudspeaker enclosure and loudspeaker enclosure parts are produced in the vacuum casting process or in the pressure gelation process.

2. A method for the production of loudspeaker enclosures and loudspeaker housing parts according to claim 1, characterized in that the housings are made of epoxy resin, anhydride hardener, filler and additives.

3. A method for producing loudspeaker enclosures and loudspeaker housing parts according to claim 2, characterized in that for the production thereof as a filler quartz powder is used, which can be added to increase strength and toughening agents.

4. A method for the production of loudspeaker cabinets and loudspeaker cabinet parts according to claim 3, characterized in that the filler needle-like filler, such as wollastonite is added.

5. A method for producing loudspeaker enclosures and loudspeaker housing parts according to claim 2, characterized in that the cast resin glass fiber chips are added.

6. A method for producing loudspeaker enclosures and loudspeaker housing parts according to claim 3, characterized in that the filler chalk and / or gum is added.

7. A method for producing loudspeaker enclosures and loudspeaker housing parts according to claims 1 to 6, characterized in that the casting resin hollow ball are added as a filler, or exclusively hollow spheres are used as a filler.

8. A method for producing loudspeaker enclosures and loudspeaker housing parts according to claims 1 to 7, characterized in that the epoxy resin mixture is added to dyes or pigments.

9. A method for producing loudspeaker enclosures and loudspeaker housing parts according to claims 1 to 8, characterized in that reinforcing fabric or reinforcing fibers of glass, carbon or natural fibers reinforce the Gießharzmasse additionally mechanically by being inserted into the mold or added to the Gießharzmasse.

10. A method for producing loudspeaker enclosures and speaker housing parts according to claims 1 to 9, characterized in that those are produced in molds with appropriate surface quality, so that the surface of the cast speaker housing part of the surface quality and surface texture of the mold corresponds, which also high-gloss surfaces without rework will be realized.

1 1. A method for producing speaker housings and loudspeaker housing parts according to claims 1 to 10, characterized in that housing cavities, the sound openings and the recesses for the speakers is realized by means of appropriately shaped mandrels.

12. A method for producing loudspeaker enclosures and speaker housing parts according to claims 1 to 1 1, characterized in that the speakers, crossovers and connection terminals are attached to threaded bushes or threaded bolts, which are previously fixed or positioned on the mold by means of appropriate devices and during the Casting resin are wrapped with casting resin, so that they form a unit with the casting.

13. A method for producing loudspeaker enclosures and loudspeaker housing parts according to claims 1 to 12, characterized in that in the cast resin before Reinforcement elements in Firm of threads, nets or mats are introduced, which are coated with the casting resin.

14. loudspeaker enclosure and loudspeaker enclosure parts made according to the method of claims 1 to 13, characterized in that the outer edges and / or corners are performed rounded, so that interference and diffraction of the sound waves are minimized.

15. Loudspeaker enclosure and loudspeaker enclosure parts made according to the method of claims 1-14, characterized in that one or all

Speaker openings are designed with a preferably funnel, which opens according to the desired directional characteristic of the speaker to the baffle front.

16. loudspeaker enclosure and loudspeaker enclosure parts made according to the method of claim 15, characterized in that one or all

Speaker openings are designed with a funnel, which opens from the speaker to the baffle front - preferably with exponential form - opens.

17. Loudspeaker housing and loudspeaker housing parts produced according to the method according to claims 1-16, characterized in that they - at least on one side - have curved surfaces.

18. loudspeaker housing and loudspeaker housing parts manufactured according to the method according to claims 1-17, characterized in that the housing walls - at least on one side - have curved and / or curved surfaces.

19. Loudspeaker housing and loudspeaker housing parts produced according to the method according to claims 1-18, characterized in that the curvature of the

Inner surfaces for the reduction of standing waves is executed with a gaussian curve-like wall thickness profile.

20. loudspeaker housing and loudspeaker housing parts produced according to the method of claim 19, characterized in that the curvature of the inner surfaces for the reduction of standing waves with a wall thickness profile, which can be described by means of an e ^x - function of a r "function or a parabolic function is executed , wherein the wall thickness increases in the housing interior.

21. Loudspeaker housing and loudspeaker housing parts produced according to the method according to claims 1-18, characterized in that the curvature of

Interior surfaces for the reduction of standing waves is designed asymmetrically and irregularly.

22. Loudspeaker housing and loudspeaker housing parts produced according to the method of claims 19, 20 and 21, characterized in that the

Reinforcement profiles are designed curved with a sloping to a Gaussian curve height so that they do not run parallel to the edges of the housing.

23. Loudspeaker housing and loudspeaker housing parts manufactured according to the method according to claims 22, characterized in that the reinforcing profiles are executed curved with sloping after a Gaussian curve height, for example with an exponential function or in the form of a different curved curve.

24. Loudspeaker housing and loudspeaker housing parts produced according to the method of claims 18 to 23, characterized in that the reinforcing profiles or wall profiles with sloping to a Gaussian curve heights

have different heights.

25. Loudspeaker housing and loudspeaker housing parts produced according to the method of claim 24, characterized in that the gain profiles or wall profiles with sloping according to a Gaussian curve heights different Have heights, preferably at least 1 saddle height with 2 altitude maxima or at least 1 altitude minimum is given.

26. Loudspeaker housing and loudspeaker housing parts produced according to the method of claims 1 to 25, characterized in that the outer shape of the loudspeaker housing cubic, or cuboid.

27 loudspeaker housing and loudspeaker housing parts prepared according to the method of claims 1 to 26, characterized in that the outer shape of the loudspeaker housing is cylindrical, conical or frusto-conical, wherein the axis may be inclined perpendicular to the base surface or obliquely to the base surface.

28. Loudspeaker housing and loudspeaker housing parts produced according to the method of claims 1 to 27, characterized in that the outer shape of the loudspeaker housing is designed similar to the shape of a bass violin body.

29. Loudspeaker housing and loudspeaker housing parts produced according to the method of claims 1 to 28, characterized in that one or all outer housing surfaces are curved or curved executed or have no flat surface (s).