KR101899150B1 - Method of producing a balance weight portion having a double - Google Patents

Abstract

The present invention relates to a method of manufacturing a balance weight having a dual specific gravity, and the constitution thereof includes a preparing step (S10); a mixing step (S20); a chip making step (S30); a first filling step (S60), a compression molding step (S50), a secondary filling step (S60), a compression cooling step (S70), and a cooling step (S80)
Each of the raw materials prepared through the mixing step and the chip manufacturing step is blended according to the blending ratio, and mixed and melted. Finally, the raw material is prepared in advance as a high-boiling chip and a low-specific-weight chip, (Weight) of the finished products, which are finished products manufactured through the molding step, the compression step, the compression cooling step and the cooling step, can be uniformly set so that the finished product can be easily standardized, and the lower part of the balance weight has a high weight, It is possible to manufacture the balance weight with a low specific gravity so that the balance weight can be stably fixed to the surface of the product to be installed, thereby leading to a robust mounting of the balance weight.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of producing a balance weight having a double specific gravity,

More particularly, the present invention relates to a method of producing a balance weight having a specific gravity, and more particularly, to a method of manufacturing a balance weight having a specific gravity, And the specific gravity (weight) of the finished products, which are manufactured through the filling step, the molding step, the compression cooling step, and the cooling step, can be uniformly set The lower part of the balance weight is made to have a high specific gravity and the upper part is made to have a low specific gravity so that it can be stably fixed to the surface of the product to be installed so that the rigid mounting of the balance weight can be induced And more particularly, to a method of manufacturing a balance weight having a specific gravity.

In general, a balance weight is used to control the balance of weight by correcting unbalance, and it is widely used in electronic equipments such as a washing machine, an elevator, a balancing device of a ship, and the like.

Conventional balance weights are produced by curing a concrete block inside the casing of the injected composite resin material.

However, the conventional method of manufacturing a balance weight has a problem in that the manufacturing process is complicated and the sealant required for manufacturing the finished product is long, resulting in low productivity of the finished product.

In addition, the injection of mortar into the case must be carried out directly by the manpower. Therefore, not only the labor cost is high, the work time is long due to manual work, and the cement is contacted with the skin of the worker by the strong alkali (PH 12) And a safety accident in which the skin is damaged.

In order to solve the above problems, the present applicant has developed "a method for manufacturing a reusable balance weight for a washing machine (Patent Registration No. 10-1407340) ".

The above-mentioned " method for manufacturing a balance weight for a washing machine to be reused (Patent Registration No. 10-1407340) "is a method of mixing a thermoplastic resin, an oil and a weight change material in a blending step; and a blending raw material blended in the blending step A mixing step of mixing the mixed raw materials evenly mixed through the mixing step at a temperature of 150 to 300 DEG C for 5 to 20 minutes to allow the mixture to be mixed evenly; A molding step of extruding a raw material into an injection mold and molding the raw material into the shape of the finished product; and a cooling step of naturally cooling the molded product through the molding step to produce the finished product.

However, the above-mentioned "method for manufacturing a balance weight for a washing machine to be reused (Patent Registration No. 10-1407340)" is a method in which a raw material is compounded (mixing step), the compounded raw materials are mixed The process of blending the raw materials is also continuously performed. In this case, the raw materials to be blended are usually discharged through the hopper in an amount corresponding to the blending weight, However, due to the nature of the hopper, changes in the weight discharged to the hopper frequently occur, and it is difficult to control the precise weight (specific gravity) of the produced balance weight, which makes it difficult to manufacture a standardized balance weight.

Furthermore, since each raw material has to be separately stored and managed, there is a problem in use that the raw material is uncomfortable to manage and use.

The above-mentioned "method for manufacturing a balance weight for a washing machine to be reused (Patent Registration No. 10-1407340)" is a method in which a raw material melted at a high temperature (150 to 300 ° C) However, when the molded article having a high temperature is exposed to a room temperature before and after 20 ° C, cracks frequently occur on the surface of the molded article due to a large temperature difference, Causing the defect occurrence rate to increase.

In addition, since cooling the product by natural cooling takes about 20 to 30 minutes, the productivity of the product is low and it is difficult to mass-produce the product.

In addition, since the balance weight, which is an article of the finished product, has a structure having the same specific gravity as a whole, there is a problem in use that the stability of contact with the surface of the product to be installed is rather difficult,

[0001] Korean Patent Registration No. 10-1407340 (Apr. 2014, 2014)

The present invention has been proposed in order to solve all of the above problems, and it is an object of the present invention to provide a process for producing a high- And the specific gravity (weight) of the finished products, which are manufactured through the filling step, the molding step, the compression cooling step, and the cooling step, can be uniformly set The lower part of the balance weight is made to have a high specific gravity and the upper part is made to have a low specific gravity so that it can be stably fixed to the surface of the product to be installed so that the rigid mounting of the balance weight can be induced And a method of manufacturing a balance weight having double specific gravity.

It is another object of the present invention to provide a method of manufacturing a balance weight having a dual specific gravity that can be easily managed and stored by manufacturing a raw material of a balance weight in a chip form, thereby enhancing manufacturing convenience for a user.

In addition, during the compression-molding step, the molding is first cooled to a temperature of 40 to 60 ° C in a process of press molding the molding with the press apparatus, thereby lowering the temperature of the molding. In the process of exposing the molding, The present invention provides a method of manufacturing a balance weight having a double specific gravity that can prevent a crack that may occur due to a temperature difference between a pair of the first and second plates,

Further, it is possible to induce rapid cooling of the molded product through the cooling step in which the molded product is subjected to the primary cooling in the process of pressing (pressing) the molded product and then the molded product is submerged in the cooling water to induce efficient mass production of the finished product And a method of manufacturing a balance weight having double specific gravity.

According to another aspect of the present invention, there is provided a method of manufacturing a balance weight having a specific gravity, comprising the steps of preparing a composite resin in which polypropylene, polyethylene and a silicone resin are mixed, , A low specific gravity mixture in which the composite resin prepared in the preparing step (S10) and the weight reducing / reducing raw material are mixed with each other, wherein the composite resin and the weight reducing / reducing raw material are mixed in a ratio of 1: 5 to 8, (S20); and mixing the low specific gravity mix and the high specific gravity mix prepared in the mixing step (S20), respectively, followed by curing and grinding to form chips (S30) of fabricating a low specific gravity chip and a high specific gravity chip as a high specific gravity chip (S30); and a step A first filling step of transferring the middle chip to an extruder through a hopper, melt extruding the chip through the extruder at 200 to 300 ° C, and injecting the melted high boiler melt into a mold using a load cell A forming step S50 of forming a plurality of binding grooves by press-molding the high-boiling-point melt filled in the mold in the first filling step S40, The low specific gravity chips manufactured in the step S30 are transferred to an extruder through a hopper, the chips are melt-extruded through the extruder at 200 to 300 DEG C, and the molten low- A second filling step (S60) of injecting and filling a predetermined amount into the mold after the step (S50); and a second filling step (S60) of pressing the molten solution filled in the mold with a press device, The temperature of the mold was 40 (S70) of maintaining a temperature of 60 deg. C so that the melt filled in the mold is gradually cooled to form a finished product having a high specific gravity at a lower portion and a low specific gravity at an upper portion; (S80) of recovering the molded product obtained in the step S70, and recovering the molded product in cooling water at 15 to 20 DEG C for 2 to 4 minutes for secondary cooling to produce the finished product as a balance weight .

The lower part of the balance weight, which is finished product through the cooling step (S80), has a high specific gravity of 2 to 3, the upper part has a low specific gravity of 1 to 2, and the total specific gravity of the balance weight is 1.5 to 2.5 And the metal powder and the abrasive grains are mixed in a weight ratio of 0.5 to 3: 1.

The chip making step S30 includes a transfer step S31 for transferring the low specific gravity mixture and the high-grade mixture to the respective extruders, an extrusion step for extruding the raw materials fed into the extruder at 250 to 300 DEG C, (S33) for pressing the raw material to be extruded through the extruder by pressing with a roller to form a flat flat plate, and a flat plate manufacturing step (S33) for crushing the flat plate produced by the flat plate producing step (S33) And a crushing step (S34) of forming a specific gravity chip and a high gravity chip, respectively.

In the second filling step S60, the extruder for melt-extruding chips is divided into forward, center, and rear sections. The front section of the extruder is heated to a temperature of 280 to 300 DEG C, and the center section is 250 To 280 DEG C, and the rear section is heated to a temperature of 200 to 220 DEG C,

The chips introduced into the extruder are rapidly melted and mixed while passing through a high temperature front section, and transferred to the center section. The melt transferred to the center section is slightly cooled at a low temperature in comparison with the front section, And the molten liquid transferred to the rear section is extruded in a further cooled state at a low temperature, so that the molten liquid is easily cooled and molded in the compression cooling step (S70).

As described above, according to the method of manufacturing a balance weight having a dual specific gravity according to the present invention, the respective raw materials prepared through the mixing step and the chip manufacturing step are blended according to the blending ratio, followed by mixing and melting, And the specific gravity (weight) of the finished products, which are manufactured through the filling step, the molding step, the compression cooling step, and the cooling step, can be uniformly set The lower part of the balance weight is made to have a high specific gravity and the upper part is made to have a low specific gravity so that it can be stably fixed to the surface of the product to be installed so that the rigid mounting of the balance weight can be induced It is effective.

In addition, since the raw material of the balance weight is manufactured in the form of a chip, it is very easy to manage and store the raw material, thereby providing convenience to the user.

In addition, during the compression-molding step, the molding is first cooled to a temperature of 40 to 60 ° C in a process of press molding the molding with the press apparatus, thereby lowering the temperature of the molding. In the process of exposing the molding, It is possible to prevent the cracks that may occur due to the temperature difference of the product, thereby lowering the defect occurrence rate of the product and enhancing the quality.

Further, it is possible to induce rapid cooling of the molded product through the cooling step in which the molded product is subjected to the primary cooling in the process of pressing (pressing) the molded product and then the molded product is submerged in the cooling water to induce efficient mass production of the finished product It is effective.

1 is a block diagram of a method of manufacturing a balance weight having a dual specific gravity according to an embodiment of the present invention.
2 is a view for explaining a manufacturing method of the balance weight having the double specific gravity shown in Fig. 1

A method of manufacturing a balance weight having a double specific gravity according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. Detailed descriptions of well-known functions and constructions that may be unnecessarily obscured by the gist of the present invention will be omitted.

1 and 2 show a method of manufacturing a balance weight having a double specific gravity according to an embodiment of the present invention. FIG. 1 is a block diagram of a method of manufacturing a balance weight having a double specific gravity according to an embodiment of the present invention. And Fig. 2 is a view for explaining a method of manufacturing the balance weight having the double specific gravity shown in Fig.

As shown in FIGS. 1 and 2, a method 100 for manufacturing a balance weight having a dual specific gravity according to an embodiment of the present invention includes a preparing step S10, a mixing step S20, a chip making step S30 , A first filling step S40, a molding step S50, a second filling step S60, a compression cooling step S70, and a cooling step S80.

The preparation step (S10) is a step of preparing a composite resin in which polypropylene, polyethylene and silicone resin are mixed, and a weight change material.

Herein, metal powder and abrasive powder are used as the weight change material, but the material is not limited thereto.

The mixing step S20 includes mixing the composite resin prepared in the preparing step S10 with the weight reducing and reducing raw material and mixing the composite resin and the weight reducing and reducing raw material at a weight ratio of 1: 5 to 8, And a high-boiling mixture in which the composite resin and the weight change material are mixed at a ratio of 1: 7 to 10.

Here, the composite resin is melted in the filling step (S40, S60) to be hounded and mixed evenly with the weight control raw material, and then the molding step S50, the compression cooling step S70, the cooling step S80 ) Constitute the body of the balance weight (B) which is the finished product, and the weight change material determines the appropriate specific gravity of the balance weight (B).

That is, the high-boiling mixture determines the lower specific gravity of the balance weight (B) and determines the upper specific gravity of the balanced weight (B).

Meanwhile, it is preferable that the metal powder and the stone powder used as the weight change material are mixed in a weight ratio of 0.5 to 3: 1 in consideration of the specific gravity of the desired finished product (balance weight).

Here, it is preferable that iron powder which is easy to purchase and low in price is used as the metal powder, but it is not necessarily used.

The chip making step S30 is a step in which the low specific gravity mix and the high gravity mix prepared in the mixing step S20 are respectively melted and then hardened and crushed to form a chip shape. The low specific gravity mix is a low specific gravity chip, In this process,

(S31) for transferring a mixture of a low specific gravity mixture and a high-boiling mixture to respective extruders, an extrusion step (S32) for extruding the raw materials introduced into the extruder by melt mixing at 250 to 300 占 폚, (S33) for forming a flat plate-like shape by pressing and pressing the raw material to be rolled by a roller, and a flat plate produced in the flat plate making step (S33) are crushed by a crusher to be formed into a low specific gravity chip and a high- And a pulverizing step (S34).

That is, since the low specific gravity chip and the high gravity chip manufactured through the flat plate manufacturing process (S33) and the crushing process (S34) after melting through the extrusion process (S32) have uniform physical properties, The specific gravity (weight) of the balance weight B, which is an article to be manufactured, can be uniformly set, and the finished product can be easily standardized.

Here, it is preferable that the chip-shaped raw material to be pulverized through the pulverizing step (S34) is formed into a fine size of about 10 mm or less to ensure the convenience of use, storage and transportation of the raw material of the chip.

As shown in FIG. 2A, in the first filling step S40, the high-boiling chip manufactured in the chip making step S30 is transferred to the extruder 1 through the hopper, Extruding the chip at a temperature of 200 to 300 캜, and injecting the molten high-boiling melt into the mold 2 in a fixed amount using a load cell.

Here, the high-boiling melt to be filled in the mold 2 is a process of forming a lower portion of the balance weight B as an end product, and the lower portion of the balance weight B is preferably formed to have a high ratio of 2 to 3 .

Meanwhile, the mold 2 determines the size and shape of the balance weight B as an end product, and may be manufactured in various sizes and shapes suitable for the field and apparatus in which the finished product is used.

As shown in FIG. 2A, in the molding step S50, the high-boiling melt filling the mold 2 in the first filling step S40 is press-molded into a press device, (10).

The forming step S50 is a step of forming a lower portion of the balance weight B as an end product. In this case, the plurality of binding grooves 10 formed in the inside of the mold are filled in the second filling step S60, So that the low specific gravity melt which is filled into the coupling groove 2 is introduced into the coupling groove 10 to guide the lower portion of the formed balance weight B and the low specific gravity melt to be firmly fixed to each other.

In the second filling step S60, the low specific gravity chips produced in the chip making step S30 are transferred to the extruder 1 through the hopper, and the chips are melted at 200 to 300 DEG C through the extruder 1 And the molten low specific gravity melt is charged into the mold 2 through the molding step S50 using a load cell.

Here, as shown in FIG. 2C, the lower part of the balance weight B after the forming step S50 is filled in the mold 2 by proceeding to the second filling step S60 before being completely hardened So that the upper portion of the lower portion of the balance weight B is partially melted and fused with the low specific gravity melt to be firmly coupled to each other.

Therefore, the upper and lower portions of the balance weight B, which is the finished product manufactured through the cooling step 80 to be formed later, are formed to have stable bonding properties as one body.

As shown in FIG. 2B, in the second filling step S60, the extruder 1 for melt-extruding chips is divided into front, center and rear sections 1a, 1b and 1c, 1 is heated to a temperature of 280 to 300 DEG C while the center section 1b is heated to a temperature of 250 to 280 DEG C and the rear section 1c is heated to a temperature of 200 to 220 DEG C ,

The chips introduced into the extruder 1 are rapidly melted and mixed through the high temperature front section 1a and transferred to the center section 1b and the melt transferred to the center section 1b flows through the front section 1a, And the melt transferred to the rear section 1c is further extruded in a state of being further cooled at a low temperature. Therefore, the squeeze cooling step S70 It is preferable to induce cooling molding easily.

In the squeeze-cooling step S70, the molten liquid filling the mold is press-molded in the second filling step S60, and the temperature of the mold 2 is maintained at 40 to 60 DEG C, 2) is slowly cooled down to a first stage, and a high specific gravity is formed in the lower portion and a low specific gravity is formed in the upper portion.

That is, in the squeeze cooling step S70, the mold 2 is molded into the shape of the finished product by the pressing force of the press, and the mold 2 is maintained at a temperature of 40 to 60 캜 to induce the primary cooling of the molding, When the mold is recovered and exposed to the outside, the temperature difference between the external room temperature and the molding is significantly reduced in comparison with the conventional balance weight manufacturing method, thereby preventing cracks caused by the temperature difference, .

The cooling step S80 is a step of recovering the molded product after the compression cooling step S70, and the recovered molded product is submerged in cooling water of 15 to 20 DEG C to perform secondary cooling for 2 to 4 minutes, As shown in the figure, the lower part is a process of fabricating a high weight ratio and the upper part is a balance weight (B) which is a finished product having a low specific gravity.

Here, the overall specific gravity of the balance weight B, which is the finished product having the lower portion of the high specific gravity and the upper portion of the low specific gravity, is 1.5 to 2.5.

Therefore, it is needless to say that the lower and upper specific gravity are appropriately adjusted in consideration of the overall specific gravity of the balance weight B as an end product.

The method 100 for producing a balanced weight having a specific gravity according to the present invention comprising the steps as described above is characterized in that each raw material prepared through the mixing step (S20) and the chip manufacturing step (S30) is blended according to the blending ratio, (S40, S60), a molding step (S50), a compression cooling step (S70), and a cooling step (S70) by providing the prepared chip in advance with an extruder, The weight of the balance weight B which is the finished product manufactured through the step S80 can be uniformly set so that the finished product can be easily standardized and the lower part of the balance weight B has a high ratio and the upper part has a low weight The balance weight B can be firmly fixed to the surface of the product to be mounted so that the balance weight B can firmly be mounted.

In addition, since the raw material of the balance weight (B) is manufactured in the form of a chip, it is very easy to manage and store the raw material, thereby providing convenience to the user.

Further, in the compression-cooling step (S70), the molding is first cooled at a temperature of 40 to 60 DEG C in a process of press molding the molding with the press apparatus, thereby lowering the temperature of the molding, It is possible to prevent the occurrence of cracks due to the temperature difference between the room temperature and the molding, thereby lowering the defect occurrence rate of the finished product and enhancing the quality.

Further, in the compression cooling step (S70), rapid cooling of the molding is performed through the cooling step (S80) in which the molding is pressurized (pressed) and then the primary cooling is performed, Thereby inducing efficient mass production of the finished product.

The method 100 for manufacturing a balanced weight having a double specific gravity according to an embodiment of the present invention having the above-described configuration produces the balance weight B in the following process.

First, polypropylene (PP), polyethylene (PE), and silicone resin are used as the composite resin, and metal powder and abrasive are used as the weight change material. (S10)

Thereafter, the prepared composite resin and the weight change material are mixed with each other, and the low specific gravity mixture in which the composite resin and the weight change material are mixed at a weight ratio of 1: 6, the composite resin and the weight change material in a weight ratio of 1: 8 Prepare by dividing into high-boiling mixture to be mixed.

At this time, the metal powder used as the weight change material and the fine powder are mixed in a weight ratio of 1.5: 1. (S20)

Thereafter, the low specific gravity mixture and the high-grade mixture are fed into the respective extruders, and the raw materials are melt-mixed and extruded at 250 to 300 DEG C (S31, S32)

The raw material extruded through the extruder is pressed and pressed by a roller to form a flat flat plate, and the flat plate is crushed by a crusher to produce a low specific gravity chip and a high gravity chip. (S33, S34)

Then, as shown in FIG. 2A, the high-boiling chip is transferred to the extruder 1 through the hopper, the chip is melt-extruded through the extruder 1 at 200 to 300 ° C, and the molten high- Is filled into the mold 2 in a fixed amount using a load cell and filled (S40)

The high-boiling melt filled in the mold 2 is pressed by a press apparatus to form a lower portion of the balance weight B as an end product, and a plurality of binding grooves 10 are formed therein. (S50)

Then, as shown in FIG. 2C, the produced low specific gravity chips are transferred to the extruder 1 through a hopper, the chips are melt-extruded through the extruder 1 at 200 to 300 ° C., The specific gravity melt is metered into the mold (2) using a load cell.

At this time, a low specific gravity melt filled into the mold 2 flows into the binding groove 10, and the upper portion of the lower portion of the balance weight B is partially melted and fused with the low specific gravity melt to be bonded to each other. (S60)

Then, the metal mold 2 is transferred to a press apparatus and pressurized at a pressure of 400 to 500 tons (t) to be formed into the shape of the balance weight B as a finished product.

At this time, the temperature of the mold 2 is maintained at 40 to 60 캜, and the molten solution filled in the mold 2 is gradually cooled while being stably molded into the shape of the finished product. (S70)

Thereafter, as shown in FIG. 2 (d), the molded product is recovered from the mold 2, the recovered molded product is secondarily cooled in cooling water at 15 to 20 ° C for 2 to 4 minutes, (B) which is a finished product with a low specific gravity. (S80)

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the invention as defined by the appended claims. You will understand the point. It goes without saying that variations can be made by those skilled in the art without departing from the spirit of the present invention. Accordingly, the scope of claim of the present invention is not limited within the scope of the detailed description, but will be defined by the following claims and technical ideas thereof.

1. Extruder 1a. Front section
1b. Center section 1c. Rear section
2. Mold 10. Coupling groove
B. Balance weight
S10. Preparation Step S20. Mixing step
S30. Chip making step S31. Transfer process
S32. Extrusion process S33. Flat plate making process
S34. Grinding process S40. The first filling step
S50. Forming step S60. The second filling step
S70. Squeeze cooling step S80. Cooling step
100. Method for manufacturing a balance weight having a double specific gravity

Claims (4)

Preparing a composite resin in which polypropylene, polyethylene and silicone resin are mixed, and a weight change material (S10);
A low specific gravity mixer for mixing the composite resin prepared in the preparation step (S10) with the weight increase / decrease raw material and mixing the composite resin with the weight increase / decrease raw material at a ratio of 1: 5 to 8; A mixing step (S20) of dividing into a high boiling mixture which is mixed in a weight ratio of 1: 7 to 10;
The low specific gravity mix and the high gravity mix prepared in the mixing step (S20) are respectively melted and then hardened and crushed to produce chips. The low specific gravity mix is formed by dividing the high specific gravity chips into the high specific gravity chips, Chip manufacturing step (S30);
The high-boiling chip fabricated in the chip making step S30 is transferred to the extruder 1 through the hopper, the chip is melt-extruded through the extruder 1 at 200 to 300 ° C, and the molten high- A first filling step (S40) of charging a metal mold (2) in a fixed amount using a load cell;
A forming step S50 of molding a high-boiling-point melt filled in the mold 2 in the first filling step S40 by press-molding the molding material into a plurality of binding grooves 10 in the inside thereof;
The low specific gravity chips manufactured in the step S30 are transferred to the extruder 1 through the hopper and the chips are melt-extruded through the extruder 1 at a temperature of 200 to 300 DEG C and the molten low specific gravity melt A second filling step (S60) of injecting a predetermined amount into the mold (2) through the molding step (S50) using the load cell;
In the second filling step S60, the molten solution filled in the mold is press-formed by a press apparatus, the temperature of the mold 2 is maintained at 40 to 60 DEG C, and the molten solution filled in the mold 2 gradually flows A squeeze cooling step (S70) in which the lower part has a high specific gravity and the upper part has a low specific gravity to be molded in the shape of the finished product while being primarily cooled; And
A cooling step (S70) of recovering the molded product after the compression-cooling step (S70), and a step of cooling the recovered molded product in cooling water at 15 to 20 DEG C for 2 to 4 minutes to prepare a finished balance weight (B) S80). ≪ / RTI >
The method according to claim 1,
The lower part of the balance weight B as an end product completed through the cooling step S80 has a high specific gravity of 2 to 3 and the upper part has a low specific gravity of 1 to 2. The total specific gravity of the balance weight B Lt; RTI ID = 0.0 > 1.5 < / RTI &
Wherein the weight change raw material is a mixture of metal powder and abrasive grains in a weight ratio of 0.5 to 3: 1.
3. The method according to claim 1 or 2,
The chip manufacturing step (S30)
A transfer step (S31) for transferring the low specific gravity mixture and the high-grade mixture to the respective extruders,
An extrusion step (S32) in which the raw material fed into the extruder is melted and mixed at 250 to 300 DEG C and extruded,
A flat plate making step (S33) of pressing and pressing the raw material extruded through the extruder by a roller to form a flat flat plate;
And a crushing step (S34) of crushing the flat plate produced in the flat plate manufacturing step (S33) with a crusher to form a low specific gravity chip and a high gravity chip, respectively.
The method of claim 3,
In the second filling step S60, the extruder 1 for melting and extruding chips is divided into front, center and rear sections 1a, 1b and 1c, and the front section 1a of the extruder 1 The center section 1b is heated to a temperature of 250 to 280 DEG C and the rear section 1c is heated to a temperature of 200 to 220 DEG C,
The chips introduced into the extruder 1 are rapidly melted and mixed through the high temperature front section 1a and transferred to the center section 1b and the melt transferred to the center section 1b flows through the front section 1a, And the melt transferred to the rear section 1c is further extruded in a state of being further cooled at a low temperature. Therefore, the squeeze cooling step S70 Wherein the weight of the weighted weight is easily guided to be cooled and molded at a predetermined temperature.

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