KR102525140B1 - Stands capable of assembling cardboard parts from recycled pulp paper waste in cross-fitting type according to space and use - Google Patents

Abstract

Provided is a sales stand that is manufactured by assembling cardboard parts made from recycled pulp paper waste in a matching format according to space and purpose. The sales stand comprises: a rear plate with a plurality of rear through holes formed in the shape of a plate; left and right side plates coupled to the rear plate and having a plurality of guide grooves formed on the inner side; and a plurality of shelves which have the shape of a plate, and a fitting piece is formed on the rear side thereof to fit into the plurality of rear through holes formed in the rear plate, and are provided with fixing protrusions on the front and are fitted into the plurality of guide grooves provided on the left side plate and the right side plate.

Description

A shelf manufactured by custom-assembling cardboard parts recycled from pulp paper waste according to space and purpose

The present invention relates to a rack manufactured by assembling cardboard parts recycled from pulp paper waste in a matching type according to space and use.

Wood and other natural resources are used as the main raw material of natural pulp paper, which causes destruction of the natural environment and waste of resources, but the use of pulp paper is gradually increasing in modern society. For example, the sales of disposable diapers in Korea are about 2 billion units per year as of 2020, and compared to 1 billion units in 2010, the amount of disposable diapers used has increased by more than twice. This increase in usage causes the consumption of a lot of raw materials and means an increase in waste, and these wastes require a lot of cost again for disposal.

Therefore, the utilization of industrial product waste of natural pulp paper has become important, and research and development for more effective use are endlessly needed.

Paper products such as diapers and paper towels generated during the production process in factories are usually mixed with polyolefin-based polymer fibers and wood pulp, or each constitutes a separate layer, and in particular, resin for enhancing wet paper strength is added to be recycled as pure pulp paper. Since this is not easy, all of these wastes are incinerated.

On the other hand, shelves are used to display products to be sold so that consumers can easily see them in a business place that sells various products, or to easily store various products.

Various types of racks have been proposed and widely used in the past, and the most common structure of display racks is to form vertical supports in four directions, and use these supports to install plate-shaped shelves in multiple stages to display products on each shelf. It is designed so that it can be placed easily.

However, there is a problem in that workability and manufacturability are deteriorated because the manufacturer must individually manufacture the shelves according to the size of the space in which the display rack is to be installed.

In addition, when parts such as shelves are damaged or worn, replacement and repair are not easy, so there are problems with follow-up management, and installation problems such as the need to use separate specialized tools when assembling and disassembling the display rack.

In addition, the conventional shelf also has a problem in that workability and manufacturability are deteriorated because the manufacturer must individually manufacture the shelf according to the size of the space in which the shelf is to be installed.

If cardboard is made by recycling natural pulp paper waste and a customized shelf can be completed by assembling a plurality of cardboard parts in various sizes and shapes, it is eco-friendly, improves installation workability, and can be customized according to space and purpose. We will be able to provide a shelf that can be used.

The problem to be solved by the present invention is to provide a shelf manufactured by assembling cardboard parts recycled from pulp paper waste in a matching type according to space and use.

The problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

The shelf of the present invention for solving the above problems is a back plate formed with a plurality of rear through holes in the shape of a plate; a left side plate and a right side plate coupled to the rear plate and having a plurality of guide grooves formed on the inner side; It is plate-shaped, and a fitting piece is formed on the rear side to be fitted into a plurality of rear through-holes formed on the rear plate, and a fixing protrusion is provided on the front side to be fitted into a plurality of guide grooves provided on the left side plate and the right side plate. It may be characterized in that it includes a plurality of shelves.

The fixing protrusions of the plurality of shelves may be provided on left and right side surfaces of locking protrusions formed on front surfaces of the plurality of shelves.

It may be characterized in that it further comprises a front support plate formed on the front surface of the lowest shelf among the plurality of shelves, coupled and reinforced while sealing the front lower part of the shelf.

The back plate, the left side plate, the right side plate and the shelf, a. Waste pulp paper collection (SCRAP collection) step; b. A first crushing step of cutting the collected waste pulp paper into a size of 10 to 50 mm; c. A second grinding step of mixing water with the first grinding product that has undergone the first grinding step and cutting it into 3 to 5 mm sizes in an agitator; d. Mixing and melting polyethylene-based or polypropylene-based materials, calcium carbonate (CaCO3), rubber, and glass fibers in the secondary pulverized product; e. Dewatering and drying the secondary pulverized material that has undergone the secondary pulverization step while moving to a shroud type conveyor; f. It may be characterized in that it is manufactured by including the step of pressing the dehydrated and dried raw material by injection molding and press.

In the melting step, 20 to 35% by weight of polyethylene or polypropylene material is melted in 100 parts by weight of the secondary pulverized product, and calcium carbonate (CaCO3) 25% by weight, rubber 10% by weight, glass fiber It may be characterized in that it is completed by mixing so as to be 15% by weight.

By constructing cardboard parts using waste raw materials, the shelf of the present invention has the effect of reducing resource waste and replacing expensive synthetic resin cardboard with an environmentally friendly product at a low price.

In addition, the shelf of the present invention has the effect of being easily assembled and used according to the space and purpose to be placed.

Naak When installing and disassembling the shelf of the present invention, the convenience of transportation and installation is improved, and the shelves of the assembled shelf can secure sufficient strength.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

1 is a state diagram showing a shelf of the present invention.
2 is a perspective view showing a dismantled state of the shelf of the present invention.
3 is a perspective view showing an assembled state of the tray of the present invention.
Figure 4 is a flow chart showing that the paperboard of the present invention is produced.

Advantages and features of the present invention, and methods of achieving them, will become clear with reference to the detailed description of the following embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, only these embodiments are intended to complete the disclosure of the present invention, and are common in the art to which the present invention belongs. It is provided to fully inform the person skilled in the art of the scope of the invention, and the invention is only defined by the scope of the claims.

Terminology used herein is for describing the embodiments and is not intended to limit the present invention. In this specification, singular forms also include plural forms unless specifically stated otherwise in a phrase. As used herein, "comprises" and/or "comprising" does not exclude the presence or addition of one or more other elements other than the recited elements. Like reference numerals throughout the specification refer to like elements, and “and/or” includes each and every combination of one or more of the recited elements. Although "first", "second", etc. are used to describe various components, these components are not limited by these terms, of course. These terms are only used to distinguish one component from another. Accordingly, it goes without saying that the first element mentioned below may also be the second element within the technical spirit of the present invention.

Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used with meanings commonly understood by those skilled in the art to which the present invention belongs. In addition, terms defined in commonly used dictionaries are not interpreted ideally or excessively unless explicitly specifically defined.

The shelf 100 of the present invention includes a back plate 110, left and right side plates 120a and 120b, a shelf 130, a front support plate 140, and a billboard 150.

The rear plate 110, the left and right side plates 120a and 120b, the shelf 130, the front support plate 140, and the billboard 150, which are each component of the shelf 100 of the present invention, may be formed of cardboard. And, of course, a plastic reinforcing plate may be embedded inside the cardboard.

The rear plate 110 has the shape of a rectangular plate, and a plurality of rear through holes (not shown) having a penetrating shape from the top to the bottom are sequentially formed, so that a plurality of rear through holes provided on the rear surface of the shelf 130 to be described later are provided. The fitting piece (not shown) of is penetrated and coupled. The left and right side plates 120a and 120b are coupled to the rear plate 110, and a plurality of U-shaped guide grooves 121 are provided in multiple stages from the top to the bottom on the inner surface, so that the shelf 130 described later The provided fixing protrusion 132 is fitted.

The left and right side plates 120a and 120b are manufactured integrally with the back plate 110 and then formed with a bending groove to facilitate folding, or manufactured separately and then combined with an adhesive such as an adhesive so that they can be bent variably. Of course, it can be manufactured.

The plurality of shelves 130 have the shape of a rectangular plate, and a fitting piece is formed on the rear surface, and the fitting piece is fitted and coupled to a plurality of rear through-holes formed in the rear plate 110 to be coupled and fixed.

In addition, a locking jaw 131 is formed on the front surface of the plurality of shelves 130 to prevent products placed on the plurality of shelves 130 from being separated from the front and falling. There is a fixing protrusion 132 protruding from the left and right sides of the ), and is coupled and fixed by fitting into a plurality of U-shaped guide grooves 121 provided on the left and right side plates 120a and 120b.

The front support plate 140 is provided on the front of the lowermost shelf among the plurality of shelves 130 installed in multiple stages, and has a reinforcement function of sealing and strengthening the front lower part of the shelf 100 of the present invention. . Of course, fixing protrusions 132 may also be formed on both sides of the front support plate 140 .

The billboard 150 is coupled to the top of the rear panel 110 and functions to guide and advertise the nature and quality of products.

Looking at the installation order, the back plate 110, the left and right side plates 120a and 120b, the shelf 130, the front support plate 140, and the billboard 150 are separately manufactured in the place where the shelf 100 of the present invention is to be placed. ) After transferring, the rear plate 110 is erected and the left and right side plates 120a and 120b are combined in a foldable state so that the horizontal cross section is 'c' shape, and then a plurality of shelves 130 After fitting the fitting piece formed on the back side of the back plate 110 into the rear through hole of the back plate 110, the fixing protrusions 132 provided on the left and right side surfaces of the locking jaws of the plurality of shelves 130 are attached to the left and right side plates 120a. , 120b) by fitting into the U-shaped guide groove 121 formed on the inside, the assembly of the shelf 100 of the present invention is completed.

The billboard 150 is selectively installed on the upper end of the rear panel 110 as needed using a fixing means such as a bolt, nut, or adhesive.

The shelf 100 of the present invention as described above has the effect of being easily assembled and used according to the space to be placed. In addition, the shelf 100 of the present invention can be customized according to the purpose by adjusting the distance between the plurality of shelves 130 and whether or not they are installed.

In addition, the effect of convenient transportation and transportation during installation and disassembly of the shelf 100 of the present invention, the effect of enabling users to install and assemble conveniently and easily, and the plurality of shelves 130 of the assembled shelf 100, etc. This has the effect of having sufficient strength.

Hereinafter, a method of manufacturing cardboard for forming the rear plate 110, the left and right side plates 120a and 120b, the shelf 130, the front support plate 140, and the billboard 150 of the shelf 100 of the present invention Explain.

Diapers, sanitary products, paper towels, etc., which are positioned as essential items in modern society, are increasing in consumption due to their convenience. As described above, a large amount of consumption encourages a large amount of production, and this phenomenon is a situation in which a certain rate of defective products is continuously generated during the production process, and thus waste is increasing.

Paper products such as diapers and paper towels generated during the production process in factories are usually mixed with polyolefin polymer fibers and wood pulp, or each constitutes a separate layer. Therefore, all of these wastes are incinerated.

Since the cardboard (component parts) of the shelf 100 of the present invention is manufactured by recycling waste pulp paper, it is possible to utilize eco-friendly resources. On the other hand, conventional panels use materials for construction materials that have strength that can withstand loads, such as synthetic resin, P.V.C. panels, aluminum, and steel. It has the disadvantage of being difficult to process and cut. In addition, the heavy weight reduces work efficiency and increases the weight of the building, so cracks may occur frequently in the panel.

In order to compensate for the above disadvantages, the present invention developed an appropriate processing method using waste pulp paper, which has the advantage of sufficient strength, no cracking, and easy processing.

Components of the shelf 100 of the present invention for achieving the above object are performed by the following embodiments.

a. Waste pulp paper collection (SCRAP collection) step 210;

The collected raw materials are inspected and separated according to the type of waste, and the foreign matter is less than 1% and the water content is less than 6%, and the waste is separated and the waste is reprocessed.

In the case of a diaper, which is one of waste pulp paper, its composition is made of 47% PE (polyethylene resin), 50% pulp, and 3% SAP (super absorbent polymer). In this way, the waste pulp paper used for reproduction is added with a resin for enhancing wet strength such as PE or polypropylene-based resin or polyolefin-based polymer resin, so that even when wet, strength is maintained and reuse is possible.

For example, paper without wet strength enhancement treatment maintains only 3 to 5% of the strength before being wet when wet, but wet strength paper maintains at least 15% of the strength before being wet even when wet. can

b. A first crushing step (220) of cutting the collected waste pulp paper into a size of 10 to 50 mm;

In the primary crushing process, the waste material is firstly crushed in a single-blade type crusher or rat tooth crusher. The secondary grinding becomes easy only after passing through the grinding process.

This is because using a grinder with a flat blade or a grinder with rat teeth is advantageous in terms of cutting polyolefin fibers, and it is also possible to use other grinders.

c. A second grinding step (230) of mixing water with the first grinding product that has undergone the first grinding step and cutting it into 3 to 5 mm sizes in an agitator;

d. Melting 20 to 35% of a polyethylene or polypropylene material in 100 parts by weight of the secondary pulverized material and mixing 25% of calcium carbonate (CaCO3), 10% of rubber, and 15% of glass fiber ( 240);

Heat is applied to the secondary pulverized material through an input and output machine, and additives are added to secure the strength and characteristics required for the double bottom panel. The pulverized material is melted by putting it in an inlet and outlet machine and applying heat. At this time, 20 to 35% of polyethylene or polypropylene material is melted, and calcium carbonate (CaCO3) 25%, rubber 10%, and glass fiber 15% The mixing process proceeds by rotation, and impurities are separated and removed.

In the secondary crushing step, the raw material is dissociated in a state in which water and the waste material are mixed and pulverized into small pieces. Through this process, short fibers of 3 to 5 mm are obtained.

Added rubber has little use in the raw rubber state, but vulcanized by adding various compounding agents or in combination with metal and fiber products is very widely used as a rubber product. Cardboard is used as a reinforcing agent by adding calcium carbonate together with rubber, and this combination has high tensile strength and elongation, and relatively low modulus (elastic modulus).

Industrially, calcium carbonate (CaCO3) is obtained by pulverizing limestone into powder and sifting it through a sieve, and then gargering it (an operation that divides particles according to their size or specific gravity using the difference in speed when solid particles free settle in the air) . Calcium carbonate is widely used in the industrial field because it is inexpensive and does not have a large specific gravity. That is, as limestone and marble, it is used as a main raw material for cement, a raw material for calcium oxide, and various neutralizing agents for steel manufacturing and building materials, and is also mixed as a reinforcing agent for rubber.

e. Step 250 of dewatering and drying the secondary pulverized material (mixture) that has undergone the secondary pulverization step while moving to the shroud type conveyor;

Secondary coarse pulverized materials (mixtures) are dehydrated and dried to be transformed into raw materials for re-molding.

f. Processing the dehydrated and dried raw material into a form of cardboard by shaping by injection and pressing with a press (260);

The cardboard molded through the above process is an eco-friendly product when waste diapers are used, and four major heavy metals, Pb (lead), Cd (cadmium), Hg (mercury), and Cr6+ (chromium), can be undetected. It is made of a safer material because it is a sanitary product used on the skin or a sanitary product that comes in contact with food used in the kitchen is recycled. Indicates that it is an eco-friendly material. In addition, as described above, it is useful as an indoor building material because it has the advantage of non-drip fire retardation when burning by using more than 15% of pulp.

Hereinafter, the material of the plastic reinforcing plate embedded inside the cardboard will be described.

Since each component constituting the shelf 100 of the present invention is made of cardboard, in order to reinforce the strength of the cardboard, a plastic reinforcing plate that is lightweight and has excellent strength is molded into the inside of the cardboard, so that the shelf 100 of the present invention This is to ensure that each component constituting the is lightweight yet high-strength can be maintained.

The plastic reinforcing plate contains 15 to 25 parts by weight of high melt strength polypropylene, 20 to 45 parts by weight of glass fiber, and 0.2 to 10 parts by weight of a titanium compound, based on 100 parts by weight of polypropylene resin. It is characterized in that it contains the composition of the part.

The plastic reinforcing plate having such a composition has excellent rigidity and dimensional stability, and has an effect of improving weak melted resin of polypropylene resin by mixing polypropylene resin and high melt strength polypropylene resin, and glass fiber and titanium compound. By including it, it has an effect of maintaining high strength while being lightweight.

Hereinafter, a coating composition for coating the outer surface of the cardboard will be described.

When the cardboard used in the shelf 100 of the present invention is exposed to an environment where moisture, rainwater, beverages, etc. can adhere or permeate, there is a problem in that moisture penetrates and deteriorates durability. In this embodiment, the cardboard This is to ensure that the durability of each component constituting the sales stand is not deteriorated even by moisture or the like by coating the outer surface to have water resistance.

The composition for coating the outer surface of the paperboard includes 5 to 25 parts by weight of a cellulose derivative, 5 to 115 parts by weight of a plasticizer, 10 to 20 parts by weight of a slip agent, and 5 to 50 parts by weight of a dispersant based on 100 parts by weight of an organic solvent. The slip agent is characterized in that any one of polyethylene wax, silicone, and stearic acid monomer.

Such a coating composition has excellent workability and is easily coated on cardboard with a thin coating film, and even when the coating film is applied thinly, excellent water resistance, oil resistance and heat sealing properties are imparted.

In addition, the above coating composition is harmless to the human body, and the paper coated with the water-soluble coating composition is biodegradable in the natural environment and returns to nature, and is an eco-friendly composition that is composted and circulates in a natural state.

In a modification of the shelf 100 of the present invention, a mixer (not shown) in step 240 of mixing the secondary pulverized material, polyethylene-based or polypropylene-based material, calcium carbonate (CaCO3), rubber, and glass fiber (240). ) can be used to produce a mixture with homogeneous quality. The mixer includes a chamber in which a mixture of secondary pulverized material, polyethylene-based or polypropylene-based material, calcium carbonate (CaCO3), rubber and glass fiber is supported, and a burner disposed on the side of the chamber to heat the chamber , a phase sensor for sensing the surface height of the mixture in the chamber, a first stirring unit disposed inside the chamber, a second stirring unit disposed inside the chamber and disposed below the first stirring unit, and a phase An electronic control unit receiving a signal from a sensor and controlling the first stirring unit and the second stirring unit may be included.

In this case, the first stirring unit moves a first blade, a first shaft forming a rotation axis of the first blade, a first rotation motor rotating the first shaft, and the first rotation motor in a vertical direction. It may include a first step motor to do. In addition, the second stirring unit includes a second blade, a second shaft forming a rotation axis of the second blade, a second rotation motor rotating the second shaft, and moving the second rotation motor in a vertical direction. A second step motor may be included. Furthermore, the first blade and the second blade may be arranged to face each other in a vertical direction.

In the mixer, when a mixture of secondary pulverized material, polyethylene-based or polypropylene-based material, calcium carbonate (CaCO3), rubber, and glass fiber is supported in the chamber, the phase sensor measures the height of the surface to obtain a sensing value. can create The electronic control unit receives a sensing value from the phase sensor and controls the first step motor so that the first blade is located on the upper side with respect to the central plane in the vertical direction of the surface, so that the first blade and the first shaft The first rotary motor can be moved in a vertical direction, and the second step motor is controlled so that the second blade is located on the lower side with respect to the center plane in the vertical direction of the water surface, so that the second blade and the second shaft The second rotary motor may be moved in a vertical direction. Then, the electronic control unit may control the first rotation motor and the second rotation motor to rotate the first blade and the second blade to rotate in different directions. As a result, in the mixer, vortices in opposite directions are formed on the upper and lower sides of the chamber, respectively, so that stirring efficiency can be increased.

In addition, at the ends of the first blade and the second blade, a first shape memory alloy extending in one direction at a first temperature or higher and a second shape memory alloy extending in one direction at a second temperature higher than the first temperature are sequentially formed. It can be stacked and arranged (a connecting member can be placed between the first shape memory alloy and the second shape memory alloy).

Therefore, in the present invention, when the temperature in the chamber rises above the first temperature during heating by the burner, the length of the first blade and the second blade increases by the shape deformation of the first shape memory alloy at the end, increasing stirring efficiency and promoting convection. , It is possible to prevent thermal deformation of a mixture of secondary pulverized material, polyethylene-based or polypropylene-based material, calcium carbonate (CaCO3), rubber, and glass fiber by intensive heating on the burner side. In addition, when the temperature in the chamber rises above the second temperature, the length of the first blade and the second blade increases as much as the shape deformation of the second shape memory alloy at the end, thereby increasing the stirring efficiency and promoting the convection phenomenon more actively. Similarly, it is possible to prevent thermal deformation of the mixture due to concentrated heating on the burner side.

Furthermore, when the first blade and the second blade rotate, when the value sensed by the phase sensor exceeds the reference value, the electronic control unit dominates the rotation of the first blade and the second blade to increase the height of the surface. It is determined that the rotational speed of the first blade and the second blade can be reduced to be slower than the current operating speed, and the output of the burner is higher than the current output by controlling the burner, that is, the temperature in the chamber is set to the first temperature. It is possible to quickly activate the first shape memory alloy and the second shape memory alloy of the first blade and the second blade by raising the second temperature or more from less than (compensating for the stirring efficiency reduced by the rotation speed).

Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art to which the present invention pertains can be implemented in other specific forms without changing the technical spirit or essential features of the present invention. you will be able to understand Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (5)

A back plate having a plurality of rear through holes formed in a plate shape;
a left side plate and a right side plate coupled to the rear plate and having a plurality of guide grooves formed on the inner side; and
It is plate-shaped, and a fitting piece is formed on the rear side to be fitted into a plurality of rear through-holes formed on the rear plate, and a fixing protrusion is provided on the front side to be fitted into a plurality of guide grooves provided on the left side plate and the right side plate. Including a plurality of shelves,
Fixing protrusions of the plurality of shelves are provided on left and right side surfaces of locking jaws formed on front surfaces of the plurality of shelves,
Further comprising a front support plate formed on the front surface of the lowest shelf among the plurality of shelves and coupled and reinforced while sealing the front lower part of the shelf,
The rear plate, the left side plate, the right side plate, and the shelf,
a. Waste pulp paper collection (SCRAP collection) step;
b. A first crushing step of cutting the collected waste pulp paper into a size of 10 to 50 mm;
c. A second grinding step of mixing water with the first grinding product that has undergone the first grinding step and cutting it into 3 to 5 mm sizes in an agitator;
d. Mixing and melting polyethylene-based or polypropylene-based materials, calcium carbonate (CaCO3), rubber, and glass fibers in the secondary pulverized product;
e. Dewatering and drying the secondary pulverized material that has undergone the secondary pulverization step while moving to a shroud type conveyor;
f. It is manufactured by including the steps of molding by injection and pressurizing the raw material that has been dehydrated and dried,
In the melting step, 20 to 35% by weight of polyethylene or polypropylene material is melted in 100 parts by weight of the secondary pulverized material, and 25% by weight of calcium carbonate (CaCO3), 10% by weight of rubber, and glass fiber ) is completed by mixing with a mixer so that it becomes 15% by weight,
The mixer includes a chamber in which a mixture of secondary pulverized material, a polyethylene-based or polypropylene-based material, calcium carbonate (CaCO3), rubber, and glass fiber is supported, and a burner disposed on a side surface of the chamber to heat the chamber. And, a phase sensor for sensing the surface height of the mixture in the chamber, a first stirring unit disposed inside the chamber, and a second stirring unit disposed inside the chamber and disposed below the first stirring unit And, an electronic control unit receiving a signal from the phase sensor and controlling the first stirring unit and the second stirring unit,
The first stirring unit includes a first blade, a first shaft forming a rotation axis of the first blade, a first rotation motor for rotating the first shaft, and a first rotation motor for moving the first rotation motor in a vertical direction. Including a 1-step motor,
The second stirring unit includes a second blade, a second shaft forming a rotation axis of the second blade, a second rotation motor rotating the second shaft, and a second rotation motor moving the second rotation motor in a vertical direction. Including a 2-step motor,
The first blade and the second blade are disposed to face each other in a vertical direction,
In the mixer, when the mixture is supported in the chamber, the phase sensor measures the height of the surface of the mixture to generate a sensing value,
The electronic control unit receives a sensing value from the phase sensor and controls the first step motor so that the first blade is located on the upper side with respect to the central plane in the vertical direction of the surface of the mixture, thereby controlling the first blade and the first step motor. The shaft and the first rotary motor are moved in a vertical direction, and the second step motor is controlled so that the second blade is located on the lower side with respect to the center plane in the vertical direction of the water surface, so that the second blade and the second shaft After moving the second rotary motor in the vertical direction,
The electronic control unit controls the first rotation motor and the second rotation motor to rotate the first blade and the second blade to rotate in different directions;
At the ends of the first blade and the second blade, a first shape memory alloy whose length increases in one direction above a first temperature and a second shape memory alloy whose length increases in one direction above a second temperature higher than the first temperature are sequentially formed. is placed as
When the value sensed by the phase sensor exceeds the reference value, the electronic control unit reduces the rotational speed of the first blade and the second blade to be slower than the current operating speed and increases the output of the burner higher than the current output. A shelf characterized in that the temperature in the chamber is raised to the second temperature or higher. delete delete delete delete

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