KR100902404B1 - Improvement of sound absorption property of wood by heat-treatment under vacuum condition - Google Patents

Abstract

CLAIMS 1. A method for improving the sound absorption performance of wood, comprising: a first step of leaving wood in an environment under a predetermined pressure reduction condition; Disclosed is a method for improving sound absorption performance of wood using a reduced pressure heat treatment method, comprising: a second step of heating a wood placed under reduced pressure for a predetermined temperature and a predetermined time.

Wood, decompression, heating, sound absorption material, sound absorption rate, sound absorption performance improvement

Description

Improvement of sound absorption performance of wood using vacuum pressure treatment {Improvement of sound absorption property of wood by heat-treatment under vacuum condition}

1 is a flow chart for explaining a sound absorbing performance improvement method of wood using a reduced pressure heat treatment method according to an embodiment of the present invention.

2A and 2B are graphs showing the sound absorption performance of lily-of-the-law using an experiment compared with a conventional unprocessed 'material' using a reduced pressure heat treatment method according to an embodiment of the present invention.

 3A and 3B are each a graph showing the sound absorption performance of paulownia tree through an experiment comparing the conventional raw material using a reduced pressure heat treatment method according to an embodiment of the present invention.

The present invention relates to a method for improving the sound absorbing performance of wood using a reduced pressure heat treatment method, and more particularly, to a sound absorbing performance improving method of wood using a reduced pressure heat treatment method which can improve the sound absorbing performance of wood by heat treating the wood under reduced pressure. It is about.

In multi-family houses such as apartments or rental buildings for offices, soundproofing is basically installed on the boundary walls. Soundproof facilities used for home or office use are usually installed for the separation of each room rather than for the purpose of soundproofing.

In this regard, soundproofing which is mainly used for soundproofing is used for a space such as a singing practice room which is used for a special purpose.

As such a facility, which can be easily installed, there is a method in which a panel-type sound absorbing or soundproofing means is attached to the entire wall.

Conventionally provided panel-type soundproofing facilities have been used to bond and fix a rigid plate such as plywood, plastic plate on both sides of a glass fiber (foam glass fabric), foam foam such as poly ethylene foam.

Sound absorbing panels have also been provided for soundproofing to absorb sound itself. The sound absorbing panel also has the function of soundproofing, but it performs an additional function of preventing ringing by absorbing sound generated indoors. Such sound absorbing panels have been widely used in lecture rooms and conference rooms equipped with electroacoustic facilities. Sound-absorbing panels reduce microphone resonance and deliver loud speaker sound. In such a sound absorbing facility, it is common to use a method of putting a sound absorbing material inside and reducing sound reflectance by allowing sound waves to directly contact the sound absorbing material.

On the other hand, the intelligibility of the sound of a human being or the sound of a musical instrument clearly as a sound property of a room varies depending on the volume of the sound, reverberation time in a room, and the shape of a room.

The reverberation is related to the amount of sound absorption and the volume of the front of the room because the energy of sound remains in the room for a certain period of time since there is a reflection sound other than the direct sound of the sounding body after the pronunciation is stopped. If the sound absorption is increased, the reverberation time is shortened and the intelligibility is increased, but if the sound absorption is too large, the volume is reduced and the intelligibility is lowered. Therefore, it is necessary to use a material having an appropriate sound absorption rate for each purpose.

Wood and wood materials are good acoustical materials for the room, but research is being conducted to use them under optimum conditions.

Sound absorption is achieved by the loss or reduction of the energy of sound. Sound absorption materials can be classified into three categories.

First, there is a porous sound-absorbing material such as glass wool or rock wool, but such materials can be fatal to people in terms of the environment, the use is limited, the price is very disadvantageous.

Secondly, there is a plate vibration-type sound absorbing material such as plywood gypsum board particle board, but this is also harmful in terms of the environment, there is a problem that it is not easy to lower the price.

Third, there is a resonance type sound absorbing material having holes in plywood or fiberboard walls with through holes. In the case of using plywood or fiberboard walls in this way, there is an advantage of low cost, but there is still a limit in improving the sound absorption performance.

In addition, in order to improve the sound absorbing performance of wood or wood materials, a method of manufacturing a sound absorbing material by a method of perforation, de-cleaning, etc. using a composite material of cement or wood particles has been studied.

In addition, as an example of a method of manufacturing a sound absorbing material using wood, which is inexpensive in terms of cost and has many advantages in terms of environment, a method of carbonizing wood to make charcoal and using it as a material for sound absorbing material has been developed. (Charcoal) There is a problem, such as flying powder, falling strength.

The present invention has been made to achieve the above problems, and an object of the present invention is to provide a method for improving the sound absorbing performance of wood using an improved pressure reduction heat treatment method to improve the sound absorbing performance by heat-treating the wood under a predetermined pressure condition. .

Method for improving the sound absorbing performance of wood using the reduced pressure heat treatment method of the present invention for achieving the above object, the method for improving the sound absorbing performance of the wood, the first step of leaving the wood in the environment of a predetermined pressure reduction condition; And a second step of heating the wood placed under the reduced pressure for a predetermined temperature and for a predetermined time.

Here, in the first step, it is preferable to reduce the pressure inside the vacuum sintering furnace to 650 to 750mmHg while the wood is put in a vacuum sintering furnace.

In addition, in the first step, it is preferable to reduce the pressure inside the vacuum sintering furnace to 700mmHg while the wood is put in the vacuum sintering furnace.

In addition, the second step may include raising the heating temperature to a predetermined maximum temperature; Maintaining a predetermined time at the maximum temperature; And lowering the heating temperature after a predetermined time has elapsed.

In addition, in the raising step, it is preferable to increase the temperature by 8 to 12 degrees per minute.

Further, in the maintaining step, it is preferable to maintain the maximum temperature for 2 minutes 50 seconds to 3 minutes 10 seconds.

In addition, in the step of lowering, it is good to lower in steps of 4 to 6 degrees per minute.

In addition, the maximum temperature is preferably 170 to 180 degrees, more preferably the maximum temperature is 175 degrees.

Moreover, it is preferable that the said timber contains paulownia or a lily tree.

In addition, the sound absorption performance improvement method of wood using the reduced pressure heat treatment method according to another aspect of the present invention for achieving the above object, while heating the wood at a predetermined temperature for a predetermined time in an environment below atmospheric pressure, by heating up to the stage before carbonization It is characterized by improving the sound absorption performance.

Here, the step of reducing the environment in which the wood is placed to 650 to 750mmHg; And heating the wood to a predetermined temperature in the reduced pressure environment.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a sound absorbing performance improvement method of wood using a reduced pressure heat treatment method according to an embodiment of the present invention.

Method for improving the sound absorbing performance of wood using a reduced pressure heat treatment method according to an embodiment of the present invention is to improve the sound absorbing performance in the production of sound absorbing material using wood.

Referring to Figure 1, first prepare the processing using wood (S10). Specifically, in the step (S10), the wood as a raw material of the sound absorbing material is placed inside the vacuum sintering furnace. Herein, the wood may be Liriodendron tulipifera or Paulownia coreana, and various types of wood may be used. That is, the present invention can be applied to all wood regardless of species.

In addition, the vacuum sintering furnace, a device widely used in the industrial field, there are various kinds according to the manufacturer, it can be used by adopting any of them. Therefore, the detailed configuration and operation relationship of the vacuum sintering furnace will be omitted.

On the other hand, as in the comparative experimental example to be described later, as an example of the vacuum sintering furnace, KOVACO KSF-100 Type model may be used.

Next, the pressure in the environment in the vacuum sintering furnace, that is, the wood is prepared, is reduced to a pressure state lower than atmospheric pressure (760 mmHg) (S11). Specifically, in step S11, the pressure is increased to about 650 to 750 mmHg by vacuum sintering, preferably, the pressure is reduced to 700 mmHg.

Then, in order to heat the wood inside the vacuum sintering to increase the temperature inside the vacuum sintering (S12). At this time, the temperature inside the step by vacuum sintering step by step, it is good to increase by approximately 8 ℃ to 12 ℃ per minute. In other words, if the internal temperature is rapidly increased by vacuum sintering, a difference occurs between the surface of the wood and the heating rate of the inside of the wood, which may cause deformation of the wood. desirable. In this way, when the temperature is gradually raised to a certain temperature, it is possible to sufficiently secure the time for heat transfer from the surface of the heated wood to the inside, thereby preventing unnecessary deformation of the wood due to heat, that is, cracking or warping. have. In addition, it is possible to suppress the occurrence of the difference in sound absorption performance over the inside and the surface of the wood.

On the other hand, in the step (S12), the wood heating temperature is heated to a predetermined maximum temperature, the maximum temperature is preferably set to approximately 170 ℃ to 180 ℃. When the timber is a paulownia or lily tree, it is preferable to set the maximum temperature to 170 ° C, and may be set to an appropriate temperature between 170 ° C and 180 ° C depending on the type of timber.

Next, the inside of the vacuum sintering furnace is maintained at the highest temperature state for a predetermined time to heat the wood (S13). In step S13, the time for maintaining the maximum temperature is set to about 2 minutes 50 seconds to 3 minutes 10 seconds. That is, the time to maintain the maximum temperature regardless of the type of wood is set to 2 minutes 50 seconds to 3 minutes 10 seconds, in particular, when the wood is paulownia or lily wood, the maximum temperature for 3 minutes to 170 ℃ It is desirable to maintain. As such, when the wood is heated to a high temperature for a predetermined time, the wood is heated to the stage before carbonization, that is, charcoal, thereby changing its structure and moisture content. Therefore, while maintaining the shape and strength of the wood, the sound absorption performance is changed to an improved state.

Next, as in the step (S13), after heating the wood to the highest temperature for a predetermined time, the temperature inside the vacuum sintering furnace is lowered step by step to lower the heating temperature (S14). In the step (S14), the temperature is lowered stepwise by 4 ℃ to 6 ℃ by minute, if the wood is paulownia or lily wood, it is preferable to lower by 5 ℃. As such, if the heating temperature is lowered step by step, as described above in step S12, it is possible to prevent unnecessary deformation of the wood due to a sudden temperature change. In other words, by lowering the heating temperature of the wood step by step, it is possible to prevent the deformation of the processed wood, such as twisting or cracking, so that an additional process or additional reinforcing member to prevent the deformation of the wood to be used as sound absorbing material is unnecessary There is an advantage to doing this.

As described above, after each step (S10, S11, S12, S13, S14) is completed, if the wood processed by the sound absorbing material is taken out from the vacuum sintering furnace, the process of improving the sound absorption performance is finished.

Hereinafter, the degree to which the sound absorption performance of the wood processed by the above method is improved will be described in detail in comparison with unprocessed wood.

The wood specimens used in the experiments used lilies and paulownia.

First, the size of the conventional specimen, which is a comparative example, which is not processed, means a specimen of unprocessed 'material', and the sound absorption rate is measured by using a FA-A790 3D engraving machine manufactured by FAWOO TECHNOLOGY with a plate having a thickness of 11 mm and a diameter of 60.8 mm. It was. The specimen (hereinafter referred to as heat treatment specimen) of the experimental example to be processed (hereinafter referred to as heat treatment specimen) was processed into the same thickness disc using the same engraver, and after heat treatment under reduced pressure, the thickness was about 10 mm due to shrinkage and the diameter was 60.8. mm.

The conventional specimens were sufficiently humidified for at least 48 hours at a temperature of 20 ± 1 ° C. and a humidity of 65 ± 2%, and then the sound absorption rate was measured.

The heat-treated specimen is first wet the wood material at a temperature temperature of 20 ± 1 ℃, humidity 65 ± 2% more than 48 hours, and then dried for 6 hours at 120 ± 1 ℃, by a reduced pressure heating method by the method of the present invention After heat treatment under reduced pressure, moisture absorption was measured after a sufficient humidity for at least 48 hours at a temperature of 20 ± 1 ° C. and a humidity of 65 ± 2%, similarly to the conventional specimens.

Also, B & K's sound absorption measurement device was used to measure the sound absorption rate, which is measured by Impedance Measurement Tube (Type 4206A), Signal Analyzer Unit (Type 2035), Power Amplifier (Type 2706), Microphone (Type 2670-2). Consists of.

The range of the measurement frequency was 500 Hz to 3.2 kHz because the size of the tube was medium, and before the measurement, a calibration was performed using a sponge, and then the absorption coefficient was measured. The sound absorption rates of the front and back surfaces of four tangential and radial section specimens were measured for each species, and the average value measured 200 times was used. In addition, the specimen was fixed using a rubber band for accurate installation of the measurement specimen.

Table 1 shows the results of measuring the sound absorption of the conventional specimen and the heat treated specimen by the same method as described above. That is, in the following Table 1, the heat treated specimens using the lilies and the paulownia trees are processed by the reduced pressure heating method as described above. Specifically, the inside of the vacuum furnace is decompressed to 700 mmHg, and the inside of the vacuum furnace is The temperature was gradually increased by 10 ° C. per minute until the maximum temperature reached 170 ° C., maintained at the maximum temperature for 3 minutes, and then lowered by 5 ° C. per minute.

Kinds Surface type Heat treatment Sound absorption Sound absorption increase rate (%) sponge 31.02 (0.13) Lily tree Tangent section Conventional Specimen 5.83 (0.35) Heat-treated specimen 10.71 (3.01) 4.88 (83.85) Radiation cross section Conventional Specimen 5.34 (0.58) Heat-treated specimen 12.69 (3.03) 7.35 (137.78) Paulownia Tangent section Conventional specimen 5.31 (0.46) Heat-treated specimen 8.08 (0.92) 2.77 (52.17) Radiation cross section Conventional Specimen 5.73 (0.30) Heat-treated specimen 8.07 (0.38) 2.34 (44.38)

In addition, Figures 2a and 2b is a graph showing the sound absorption rate of the frequency 500 ~ 3.2 kHz for each of the conventional specimens and heat-treated specimens of the lily tree. 3A and 3B are graphs showing sound absorption rates of frequencies of 500 to 3.2 kHz for the conventional specimens and the heat-treated specimens of paulownia.

As can be seen from Table 1 and Figures 2a to 3b, the average sound absorption of the paulownia and lily wood material has a sound absorption of 5.3% to 5.8%, regardless of the radiation cross section or tangential cross section. That is, as in the case of the present invention, it can be seen that the sound absorption rate is significantly increased in the heat-treated specimen subjected to the reduced pressure heating treatment, as in the case of the present invention. And the sound absorption rate increases regardless of the species. Therefore, in the embodiment of the present invention has been described in detail with a focus on paulownia and lily trees, this is just an example, even if the use of various types of wood will be able to obtain the same sound absorption increase effect.

In addition, regardless of the species or cross-sectional shape of the wood, as measured by 10.71, 12,69 and 8.08, 8.07, it can be seen that the sound absorption rate increased by 45% to 138% compared to the conventional specimen.

According to the method for improving the sound absorption performance of wood using the reduced pressure heat treatment method of the present invention as described above, the sound absorption rate can be increased by heating the wood to be used as the sound absorbing material at a predetermined temperature under reduced pressure conditions. In this way, the wood, which is widely used as a sound absorbing material, can be improved by absorbing and reducing the disadvantages such as charcoal blowing without changing the wood into charcoal by carbonization. There is an advantage that can increase the comfort.

Claims (17)

In the method for improving the sound absorption performance of wood, A first step of leaving the wood in an environment of a set pressure reduction condition; And a second step of heating the wood placed under the reduced pressure for a predetermined temperature and a predetermined time. In the first step, While the wood is put in a vacuum sintering furnace, the pressure inside the vacuum sintering furnace to reduce the pressure to 650 to 750mmHg, In the second step, Increasing the heating temperature by 8 to 12 ° C. per minute up to a set maximum temperature of 170 ° C. to 180 ° C .; Maintaining at a maximum temperature of 170 ° C. to 180 ° C. for a set time of 2 minutes 50 seconds to 3 minutes 10 seconds; And a step of lowering the temperature stepwise by 4 to 6 ° C. per minute after the step of maintaining. The method of improving sound absorption performance of wood using a reduced pressure heat treatment method. delete The method of claim 1, In the first step, A method for improving the sound absorption performance of wood using a reduced pressure heat treatment method, wherein the wood is placed in a vacuum sintering furnace, and the pressure inside the vacuum sintering furnace is reduced to 700 mmHg. delete delete delete delete delete The method of claim 1, The maximum temperature is, Method for improving sound absorption of wood using reduced pressure heat treatment, characterized in that 175 ℃. delete The method of claim 1, The wood, Method for improving the sound absorption performance of wood using paulownia or lily wood. delete delete delete delete delete delete

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