DK179276B1 - Fully cast speaker cabinet with integrated bass reflex produced by sand casting in a gray cast iron alloy. CSRC - Google Patents

Abstract

Cast sound reproduction is a unique newly invented speaker concept based on the best components of the market and a newly invented speaker cabinet design, material selection and manufacturing method. See Appendix 9. The unique feature of the invention is that the generation is based on the fact that the cabinet is produced in one and only one stage of production using the sand casting technology while having a natural interior petrule geometry, reflecting the high frequency sound waves while the integrated bass reflex lets the speaker breathe freely. The geometric design and material selection of the speaker cabinet makes it immune to mechanical vibrations. The uniqueness of this invention is that gray cast iron's sound attenuating properties and strength have been used to produce, in a single production step, a speaker enclosure with an internal geometry that reflects the high-frequency sounds in such a way that no resonance is created while the integrated bass reflex ensures that the speaker unit can breathe, creating standing pressure waves.

Description

< ¹ θ> DENMARK (10)

< ¹² > PATENT WRITING

Patent and

Trademark Office (51) Int.CI .: B22C 9/02 (2006.01) B 22 D 3/00 (2006.01) C 21C 1/00 (2006.01)

H 04 R 31/00 (2006.01) (21) Application Number: PA 2013 00376 (22) Filing Date: 2013-06-19 (24) Running Day: 2013-06-19 (41) Aim. available: 2017-06-06 (45) Patent Notice bkg. on: 2018-03-26 (73) Patent holder: DANSK SKALFORM A / S, Birkevej 59, Tandrup, 9600 Aars, Denmark (72) Inventor: Søren Dissing, Vestvej 1,9600 Aars, Denmark (74) Proxy: TMP Patent ApS , c / o Tenna Pedersen, Ternevej 2 B, 3 tv., 2000 Frederiksberg, Denmark (54) Designation: Fully cast speaker cabinet with integrated bass reflex produced by sand casting in a gray cast iron alloy. CSRC (56) Published publications:

JP S59230394 A JP 2000125381 A JP 2001285977 A JP 2000125382 A JP S59107061 A CN 1283950 A DE 29609681 U1 EP 1682291 B1 (57) Summary:

Cast sound reproduction is a unique newly invented speaker concept based on the best components of the market and a newly invented speaker cabinet design, material selection and manufacturing method. See Appendix 9. The unique feature of the invention is that the production is based on the fact that the cabinet is produced in one and only one stage of production using the sand casting technology while having a natural interior petrule geometry, and that reflects the high frequency sound waves while the integrated bass reflex lets the speaker breathe freely. The geometric design and material selection of the speaker cabinet makes it immune to mechanical vibrations. The uniqueness of this invention is that gray cast iron's sound attenuating properties and strength have been used to produce, in a single production step, a speaker enclosure with an internal geometry that reflects the high frequency sounds in such a way that no resonance is created while the integrated bass reflex ensures that the speaker unit can breathe, creating standing pressure waves.

To be continued ...

HG. First

Description:

The invention relates to a method of producing a speaker cabinet in a molding material.

JPS59230394 A and JP2000125381 A both disclose the manufacture of speaker enclosures or components therefor where gray cast iron is used.

CN1283950 A describes the manufacture of ferrous items for speakers using sand casting.

Usually, speaker cabinets are made of wood MDF plate painted or lined with metal foil, plastic or thin plate in stainless steel using cushioning inserts to reduce, and sometimes completely remove the resonance.

Let's start with the human hearing, which can perceive tone in the frequency range approx. 20 - 20,000 Hz. The sound itself is pressure waves with very small pressure variants, approx. one hundred thousandth of the atmospheric pressure, see Appendix 4.

Characteristic of sound is that high-frequency sounds behave mainly in the same way as light rays, whereas low-frequency sounds behave like waves.

The devices that produce the sound oscillate mechanically and can, in given situations, create resonance and greatly distort the sound image if one of the intrinsic oscillations of the cabinet is hit.

The choice of material for the cabinet influences the determination of the intrinsic frequency, as it is well known that the tendency for resonance can be significantly reduced by reducing the bulk density of the cabinet by padding the inside with damping material.

Disregarding the geometric influence of the cabinet in relation to the ability of the cabinet to come is simplified to the following expression.

self-swing, can influence the material

Show where E is the modulus of elasticity of the material and p is the density.

From this, using the data set out below, it appears that the material eigenvalue index of MDF plates is ~ 0.0625.

For the metals, for Gray Iron it will be ~ 0.0508, SG iron ~ 0.0573, Alu- bronze «0.0430, Aluminum alloys« 0.0907, steel «0.0588 and stainless steel« 0.5884.

Typical data for MDF plates:

RAW MDF Plate

Primary use indoors in buildings. A smooth and neat plate that is similar and homogeneous in the material. Suitable for shelves, window frames and the like.

Stable and easy to process. Milling tools can advantageously be used (,) where decorations or roundings are desired on the edges of the plate.

room wall:

Modulus of elasticity:

Bending Tensile strength:

Source:

755 kg / m ³

2700 N / mm ² (EN 310)

N / mm ² (EN 310) www .raw-products.info

Swiss MDF Decor

Medium Density Fibreboard produced to formaldehyde quality class E1, with a decorative melamine faced surface to be used as specified in the European

Standard DIN 68785 Bulk density: Flexural strength: 700/750 kg / m ³ 20.0 N / mm ² (EN 323) (EN 310) Flexural e-module: 2'200 N // mm ² (EN 310) Transverse tensile strength 0.55 N // mm ² (EN 319)

Source: www.kronospan.com

Typical Mechanical Property Data for a Suit of Selected Material and Alloys.

Gray Cast Iron

Density: 7100 kg / mm ³

Tensile strength: 270 - 400 N / mm ²

Modulus of elasticity: 1.1-1.3 * 10 ⁵ N / mm ²

The unique damping effect of gray irons is associated with its inherent natural composite microstructure, which is strongly dependent on melting alloy composition and inoculation.

Ductile Iron, Nodular Cast Iron (SG Iron)

Density: 7200 kg / m ³

Tensile strength: 270 - 400 N / mm ²

Modulus of elasticity: 1.7 * 10 ⁵ N / mm ²

Alu-Bronze Alloys:

Density: 7890 kg / m ³

Tensile strength 540-800 N / mm ²

Modulus of elasticity: 1.15 * 10 ⁵ N / mm ²

Aluminum Bronzes are twice as effective as steel in their ability to dampen vibrations.

Aluminum:

Density: 2700 kg / m ³

Tensile strength: approx. 250 N / mm ²

Modulus of elasticity: 6-7 * 10 ⁴ N / mm ²

Black Steel (aim steel):

Density: 7800 kg / m ³

Tensile strength, yield: about 300 N / mm ²

Modulus of elasticity: 2.1 * 10 ⁵ N / mm ²

Stainles Steel:

Density: 7800 kg / m ³

Tensile strength, yield: about 210 N / mm ²

Modulus of elasticity: 2.0 * 10 ⁵ N / mm ²

From this material index it is generally seen that there is no great difference between whether the cabinet is made in a metal alloy or wood when internal padding is not taken into account. Gray cast iron is a particularly interesting material, since the natural damping capacity of this material can be more than a hundred times that of all the other metals.

Now we go back to the fact that low-frequency sound behaves like pressure waves, whereas the high-frequency sound pattern of movement can be compared more closely to reflected light, the interior surface design of the cabinet benefits. The sound of the treble, when constantly reflected, is interrupted in such a way that no standing sound waves can occur which may disturb the sound image of the speaker unit.

This pattern can be molded by using a sand core which is placed directly in molds and forms the inner geometry. The uneven geometric design of the surface is normally based on a hexagonal pattern that can be introvert / concave or extrovert / convex. After that, it is the natural slip angles for the core to come out of the core box after firing and hardening that (change) the geometry of the petruled surface.

The invention provides a method as set forth in the preamble of the specification, wherein the speaker cabinet is also manufactured in a sand mold to provide an outside geometry and a sand core to provide an inside geometry that the speaker cabinet is integrally molded and made of one of the following materials: bronze, stainless steel, SG iron, aluminum or preferably gray cast iron, and that the sand core provides an interior geometric pattern which is an introvert / concave or extrovert / convex hexagonal pattern, whereby the speaker enclosure's finished face is constituted by hexagonal extrovert / convex / concave patterns.

Further embodiments are set forth in claims 2, 3 and 4.

The base unit which produces the low frequency sounds moves relatively much air which can relate in standing pressure waves. This problem is solved by the embedded bass reflex.

The invention will be explained in more detail with reference to the figures where

Figure 1 shows a perspective view of a speaker cabinet according to the invention.

Figure 2A shows a perspective view of the sand core from the perspective.

Figure 2B shows a perspective view of the sand core obliquely from behind.

Figures 3A, B show CAD images of the shape and position of the sand core of a speaker enclosure according to the invention viewed from the front and the rear view respectively.

Figures 4A-C show the complete pre-cast speaker enclosure of the invention.

FIG. 5 shows pre-fabricated speakers Iron Sound CSRC according to the invention.

Figure 6A shows the division of frequency range.

Figure 6B shows the relationship between frequency and a sound pressure level.

Figure 7A shows the resonance measurement of a CSRC cabinet made in SG iron and without using a pattern according to the invention.

Figure 7B shows the resonance measurement of a CSRC cabinet made in SG iron and using a pattern according to the invention.

Figure 7C shows the resonance measurement of a CSRC housing made of gray cast iron and using a pattern according to the invention.

Figure 1A shows a speaker cabinet made in accordance with the invention, showing the interior surface of the cabinet.

FIG. 2A-B shows sand cores for making a speaker enclosure as shown in Figure 1. The sand cores are shown front and back and are CAD images of the sand core, which creates the internal geometry of the speaker / cabinet CSRC, while Figure 3A, B shows CAD images of shape and positioning the sand core of a loudspeaker cabinet according to the invention viewed from the front, respectively - Fig. 3A - and from the rear, from Fig. 3B.

Figures 4A-C are images of the complete pre-cast CSRC speaker cabinet. The treble is mounted directly here in the three holes shown in the upper left and the base unit in the five holes in the lower right. The rest appears to be cast without machining.

Figure 5 is images of 3 pre-produced speakers Iron Sound CSRC. The speaker enclosures are seen here in painted cast iron, but can also be made in bronze alloys, where the surface may be annealed in various ways to promote a color play, polished stainless steel, corten steel, aluminum or iron (SG).

The choice of material is free, since it is the production method coupled to the mold, especially the internal geometry, that can only be made via the sand casting process of single-molded cabinets that is important.

Cast sound reproduction is a unique speaker concept based on the best components of the market and a newly invented speaker cabinet design, material selection and manufacturing method.

To illuminate the effect of the interior 3D surface versus a smooth surface as well as material selection, 3 cabinets were cast. One in Sg iron with smooth surface where all the irregularities on the core were spaced out, one in Sg iron with a core with the described pattern and one in gray cast iron with a pattern. By comparing resonance measurements directly on these three enclosures, the effect of with / without pattern and material selection can be elucidated. There is a big difference between SG iron and gray cast iron in terms of strength and sound. The important thing here is that when you turn on Sg iron, it sings while gray cast iron is completely dead.

From Figures 7A-C, when comparing Figure 7A with Figure 7B, it is clearly seen that the interior pattern housing has less resonance propensity than that without pattern. By comparison with Figure 7C with Figure 7B, it is seen that the cabinet cast in gray iron with pattern clearly performs better than the corresponding cast in Sg iron.

From these measurements it can be clearly seen that the speaker cabinet with gray molded internal pattern works best and is therefore the optimal solution.

Summary

Cast sound reproduction is a unique newly invented speaker concept based on the best components of the market and a newly invented speaker cabinet design, material selection and manufacturing method. See Figure 5.

The unique feature of the invention is that the production is based on the fact that the cabinet is produced in one and only one stage of production using the sand casting technology while having a natural interior petrule geometry, reflecting the high frequency sound waves while charging the integrated bass reflex the speaker breath freely.

The geometric design and material selection of the speaker cabinet makes it immune to mechanical vibrations.

The uniqueness of this invention is that gray cast iron's sound attenuating properties and strength have been used to produce, in a single production step, a speaker enclosure with an internal geometry that reflects the high frequency sounds in such a way that no resonance is created while the integrated bass reflex ensures that the speaker unit can breathe, creating standing pressure waves.

Mechanical Properties of Gray Iron - Damping Capacity

The relative ability of a material to absorb vibration is evaluated as its damping capacity. The quelling of vibration by converting the mechanical energy into heat can be very important in structures and in moving parts devices. Components made of materials with high damping capacity can reduce noise such as chatter, ringing and squealing, and also minimize the level of applied stresses.

The exceptionally high damping capacity of gray cast iron is one of the most valuable qualities of this material. For this reason it is ideally suited for machine bases and supports, engine cylinder blocks and brake components. The damping capacity of gray iron is considerably greater than that of steel or other kinds of iron. This behavior is attributed to the flake graphite structure of the gray iron, along with its unique stress-strain characteristics. The relative damping capacity of several different metals is illustrated in the table

1. Damping capacity decreases with increasing strength as the larger amount of graphite present in the lower strength irons increases the energy absorbed. Larger cast section thicknesses increase damping capacity and inoculation usually decreases it. Heat treating can also have an appreciable effect on damping capacity.

Table 1. Relative Damping Capacity.

material

White Iron:

Malleable Iron:

Ductile Iron:

Gray Iron, Fine Flake: Gray Iron, Course Flake: Steel:

Armco: Iron Aluminum:

2-4 * 10 ⁴ 8-15 * 10 ⁴ 5-20 * 10 ⁴ 20-100 * 10 ⁴ 100-500 * 10 ⁴ 4 * 10 ⁴ 5 * 10 ⁴ 0.4 * 10 ⁴

Natural Log Ratio of Successive Amplitude

Reference: http: //www.atlasfdry.eom/grayiron-damping.htm#table4

Facts about Sound

What is sound?

Sound is very small fluctuation in the air pressure, up and down around the pressure of the atmosphere. And little ones really need to be taken literally. Even for a sound that is so powerful that you have to use hearing protection, the pressure only fluctuates approx. one hundred thousandth of the atmospheric pressure. So fluctuations up and down between 0.99999 and 1.00001 times the atmospheric pressure. The weakest sound we can hear is at 0.000000000002 times the atmospheric pressure.

Sound pressure and sound pressure level.

The sound pressure describes the physical strength of the sound, ie whether it is strong or weak. The unit of measurement for sound pressure is Pascal - just like the barometer level. Pascal abbreviated Pa. The weakest audible sound is about 0.00002 Pa, and a very loud sound is e.g. 20 Pa. With this powerful sound pressure, the sound causes pain.

It is difficult to work with sound pressure in Pascal because of the large differences in values for loud and weak sounds. Instead, in practice, sound pressure level is measured, which is measured in the unit decibel (dB). The two examples will be converted to sound pressure level 0 dB for the weakest audible sound and 120 dB for the loud sound.

The decibel scale is logarithmic and, as an added benefit, it fits our perception of sound better than the linear Pascal scale. As a rule of thumb, you can just hear a difference in the strength of two sounds if they have a difference of 1 dB. A difference of 3 dB is clearly audible, and if two sounds have a difference of 10 dB, one will sound about twice as loud as the other. However, at low frequencies, the subjective increase in strength occurs faster; Thus, at 20-30 Hz, only about 5 dB before the sound is perceived as twice as loud.

frequencies

The pitch of the sound is determined by how fast the oscillations are. It is called the frequency of sound and it is measured in Hertz, which is abbreviated Hz. Deep tones have low frequencies (few Hz), high tones have high frequencies (many Hz).

Most sounds are between 20 Hz and 20000 Hz. Sometimes it is called the audible area. However, the term is not very well chosen because it is actually good to hear frequencies below 20 Hz, while it is the fewest people who can hear frequencies up to 20000 Hz.

Sound with frequencies above 20000 Hz is called ultrasound, and sound with frequencies from approx. 2000 Hz to 20000 Hz are called high frequency sounds. Low frequency sounds are bass tones or deep roaring sounds with frequencies from 20 Hz to approx. 200 Hz. Sound with frequencies below 20 Hz is called infrared. Between the high-frequency and low-frequency sounds, there are the middle tones, where common speech is placed, among other things. 1000 Hz is also called 1 kilohertz, abbreviated kHz. 20000 Hz, for example, can also be written as 20 kHz. The division of the frequency range is illustrated in Figure 6A.

The human hearing

Human hearing is not as good at capturing sounds at different frequencies. In general, low-frequency sounds must be more powerful than medium- and high-frequency sounds before they become audible.

The sensitivity of people to different frequencies has been investigated by determining the hearing threshold (ie, the limit of how weak tones we can hear). There is a standard above the hearing threshold for 18-25 year old normal hearing persons. It is shown in Figure 6B. The figure also shows a dashed line of hearing threshold for the infrared sound area. This one is based on measurements with far fewer people and it is not standardized.

It is seen that around 1 kHz the hearing threshold is close to 0 dB. At 3-4 kHz the threshold is lower, so we hear better at these frequencies. Don't be distracted by the fact that the dB values here are negative. It is not a negative sound or an anti sound, but the sound power is just weaker than what (,) we call 0 on the logarithmic axis. At high frequencies, the curve rises, which means we have a harder time hearing these tones. Even at low frequencies, the threshold rises - even more - so we hear worse here. At 100 Hz, the threshold is more than 20 dB and almost 80 dB is needed before the average person can hear a 20 Hz tone.

The hearing ability and thus the hearing threshold varies from person to person. The standardized threshold is calculated as an average over many people and therefore some will hear better and others inferior.

Most are (within) a range of ± 10 dB, ie from 10 dB below the curve to 10 dB above the curve. Even from one's twenties, however, hearing begins to deteriorate, and above all, it goes beyond the ability to hear the high frequencies.

Claims (4)

REQUIREMENTS A method of manufacturing a speaker enclosure in a molding material characterized in that the speaker enclosure is manufactured in a sand mold to provide an outside geometry and to a sand core to provide an inside geometry that the speaker enclosure is single-molded and made of one of the following materials: bronze , stainless steel, SG iron, aluminum or preferably gray cast iron, and that the sand core provides an interior geometric pattern which is an introvert / concave or extrovert / convex hexagonal pattern, whereby the speaker cabinet's pre-molded inner face is hexagonal extroverted or convex. introverted / concave patterns. Method according to claim 1, characterized in that a bass reflex is produced as an integral part of the speaker cabinet during its manufacture. Method according to any of the preceding claims, characterized in that the pre-cast and single-cast speaker cabinet is molded without machining other than providing holes for mounting a treble unit and providing holes for mounting a base unit. Speaker cabinet made by the method according to claims 1-3, characterized in that the outer surface of the speaker cabinet consists of 2 composite spherical shells made out of a casting material, the selected casting material is gray cast iron and the inner surface of the speaker cabinet is a hexagonal pattern which is extrovert / convex or introvert / concave.