JP6761567B2 - Manufacturing method of linear resin molded product - Google Patents

Description

The present invention relates to a method for manufacturing a linear resin molded product, and in particular, a linear resin molded product used as a raw material in a modeling device for constructing a three-dimensional object (object) such as a so-called 3D printer. It relates to a manufacturing method.

A so-called 3D printer has been attracting attention as a method for forming a three-dimensional object, and it has become possible to easily create a three-dimensional object having a complicated shape, which has been difficult to realize until now. By using a 3D printer, it is possible to process even a shape that cannot be realized by a normal method by stacking arbitrary materials such as resin and metal.

Several types of 3D printers are known, and among them, the method of extruding a resin strand (linear body) and laminating and depositing it (Fused Deposition Modeling) is advantageous in terms of cost. For this reason, development is underway in various fields (see, for example, Patent Document 1 and Patent Document 2).

For example, in the laminated modeling system of Patent Document 1, a filament, which is a modeling material, is supplied to an extrusion head, the filament is melted by a liquefier mounted on the extrusion head, and the molten filament is extruded onto a base through a nozzle. The extrusion head and base move relatively to form a 3D model, laminating a large number of linear and layered materials to produce a 3D model.

Patent Document 2 describes that the modified ABS material is delivered to the extrusion head of a laminated deposition system by extrusion, and the delivered modified ABS material is melted in the extrusion head under conditions that improve the response time of the extrusion head. Disclosed is a method of constructing a 3D object, which comprises depositing a molten thermoplastic material layer by layer to form the 3D object.

In this type of method, the basic idea is to melt and deposit a resin material, and a resin strand (striatum) is used as a raw material. Patent Document 3 and Patent Document 4 disclose resin strands used as raw materials, supply methods thereof, and the like.

Patent Document 3 discloses a composition for producing a three-dimensional object, but in an extruder for producing a modeled object, it is supplied as a flexible filament to an extrusion head. The filament is melted in a liquefier carried by the extrusion head. The liquefier heats the filament to a temperature slightly above the freezing point to bring it into a molten state. The molten material is extruded onto the pedestal through the orifice of the liquefier.

Patent Document 4 discloses a filament cassette and a filament cassette receiver that supply filaments in a three-dimensional deposition modeling machine. Patent Document 3 provides a method for engaging and disengaging a filament with a modeling machine in a simple manner so that the filament can be realized in a manner of protecting the filament from moisture in the environment.

Special Table 2009-500194 Special Table 2010-521339 Japanese Patent No. 5039549 Japanese Patent No. 4107960

In the method of supplying three-dimensional objects in a laminated manner by supplying the resin strands to the extrusion head while melting them as described above, the wire diameter of the resin strands used is constant and the alignment is close to a perfect circle. This is very important. This is because if the wire diameter or alignment of the resin strands used changes, the amount of resin supplied from the extrusion head changes, which leads to a decrease in molding accuracy of the three-dimensional object to be constructed.

Generally, a resin strand is manufactured by continuously extruding a melt-kneaded resin material from a mouthpiece of an extruder, cooling and solidifying the resin material, and then winding the resin material. However, due to fluctuations in extrusion conditions and winding conditions, the wire diameter And linear fluctuations may occur, which is difficult to avoid. In addition, the reality is that little attention has been paid to the wire diameter and alignment of resin strands.

The present invention has been proposed in view of such conventional circumstances, and provides a method for producing a linear resin molded product having a constant wire diameter and a cross-sectional shape close to a perfect circle. The purpose is to provide.

In order to achieve the above-mentioned object, the method for producing a linear resin molded product of the present invention is a method for producing a linear resin molded product used in a 3D printer of a heat melt lamination method, in which a melt-kneaded resin material is used. The sizing device is characterized in that it is continuously extruded from an extruder via a mouthpiece, and the extruded linear resin molded product is passed through a cooled sizing device while being vacuum-sucked, and then cooled and solidified and wound up. Has a space having a circular cross section, and is characterized by having a plurality of vacuum suction grooves on a surface facing the space.

The vacuum sizing method is known as a technique for improving the diameter accuracy in the molding of a tube (hollow resin molded product), but vacuum suction is attempted in the sizing of a solid linear resin molded product. I have never done it. However, as a result of diligent studies by the present inventors, it is clear that even in the sizing of a solid linear resin molded product, the wire diameter becomes constant and the alignment becomes close to a perfect circle by performing vacuum suction. It became. This is a finding that has never been obtained before.

According to the method for producing a linear resin molded product of the present invention, it is possible to provide a method for producing a linear resin molded product having a constant wire diameter and a cross-sectional shape close to a perfect circle. For example, by using this as a raw material for a three-dimensional object, highly accurate modeling becomes possible.

It is a schematic perspective view which shows an example of the linear resin molded article to which the manufacturing method of this invention is applied. It is sectional drawing of the linear resin molded article shown in FIG. It is a schematic perspective view which shows an example of the streak resin molded body of a two-layer structure. It is sectional drawing of the linear resin molded article shown in FIG. It is a side view of the apparatus which manufactures a linear resin molded article. It is a top view of the apparatus which manufactures the linear resin molded article of two layers composition. It is an exploded perspective view which shows the structural example of the mold used at the time of manufacturing the linear resin molded body of two-layer structure. It is an exploded perspective view of the sizing device of the device shown in FIG. It is a top view of the sizing device of the device shown in FIG. 3, and is the figure which shows by partially breaking the upper member.

Hereinafter, embodiments for carrying out the present invention (hereinafter, referred to as “embodiments”) will be described in detail with reference to the accompanying drawings. The same elements are numbered the same throughout the description of the embodiment. In addition, the drawings shall be viewed in the direction of the reference numerals.

First, the outline of the 3D printer will be briefly described. The basic mechanism is to create a three-dimensional object, that is, a 3D (three-dimensional) object by stacking cross-sectional shapes using 3D data created by a computer as a design drawing. As the method, for example, an inkjet method in which a liquid resin is irradiated with ultraviolet rays or the like and gradually cured, a powder fixing method in which an adhesive is sprayed on a powder resin, and a resin melted by heat are stacked little by little. There are methods such as the Fused Deposition Modeling method. The linear resin molded product according to the present embodiment is used in the Fused Deposition Modeling method, and is supplied to a 3D printer in a state of being wound on a reel, for example.

As the linear resin molded body used in the 3D printer of the hot melt lamination method, one composed of a single resin such as ABS resin is generally used. 1 and 2 show a so-called single-layer linear resin molded body 10 composed of a single resin. The single-layer linear resin molded body 10 is formed by processing a single resin into linear strips, and has an extremely simple structure. The present invention is mainly applied to the production of this single-layer linear resin molded product 10.

Of course, the production method of the present invention is applicable not only to this, but also to, for example, a linear resin molded product having a multi-layer structure. In a 3D printer, there is a problem that it bends or breaks during modeling, absorbs moisture after opening and deteriorates in quality, and it is difficult to model with a highly fluid material in the Fused Deposition Modeling method. In order to solve this problem, a first layer containing a thermoplastic resin and a second layer covering the first layer and containing a material different from the first layer are provided, and the second layer is the first layer. It is preferable to use a two-layered linear resin molded body that is extruded and molded while covering one layer, and the present invention has a multi-layered linear resin molded body such as a two-layered linear resin molded body. It is also suitable to be applied to the production of a resin molded body.

The configuration of the two-layered linear resin molded body will be described with reference to FIGS. 3 and 4. As shown in FIG. 3, the linear resin molded body 10 is a molding material used in a fused deposition modeling 3D printer. The first layer 21 and the second layer 22 that covers the first layer 21 and contains a material different from that of the first layer 21 are provided.

The first layer 21 is formed in a columnar shape and contains a thermoplastic resin. As the thermoplastic resin, for example, an acrylonitrile-butadiene-styrene copolymer resin (ABS resin) can be preferably used.

The second layer 22 is formed in a cylindrical shape so as to cover the first layer 21, and the linear resin molded body is melted and softened with the second layer 22 covering the first layer 21, and the extrusion head of the 3D printer. A 3D model is formed by melting and extruding the second layers while maintaining the state of being covered with the resin, and fusing and laminating the second layers. The thermoplastic resin constituting the first layer and the second layer of the linear resin molded product of the present invention may be any material as long as it can be extruded, and can be appropriately selected according to the function to be imparted to the linear resin molded product. .. For example, in addition to acrylonitrile-butadiene-styrene copolymer resin (ABS resin), amorphous resins such as polystyrene, polyvinyl chloride, polymethylmethacrylate, polycarbonate, and modified polyphenylene ether, polyolefin resins such as polyethylene and polypropylene, polyester, and polyamide. , Crystalline resins such as polyvinyl alcohol, olefin-based, styrene-based, polyester-based thermoplastic elastomers, and mixtures thereof are preferably used. Further, inorganic additives such as carbon black, carbon fiber, glass fiber, talc, mica, nanoclay and magnesium, antioxidants, lubricants, colorants and the like can be appropriately mixed.

The second layer 22 is made of a relatively hard material when the first layer 21 is soft, and has a function of protecting the first layer 21 from bending the first layer 21. For example, when the first layer 21 is a styrene-based elastomer, the second layer 22 is made of a hard acrylonitrile-butadiene-styrene copolymer resin (ABS resin), and the hard second layer 22 makes the first layer 21 soft. Suppresses bending. As a result, the linear resin molded body 10 has an appropriate hardness as a whole and is easy to handle as compared with the linear resin molded body composed of a single elastomer, so that good mechanical suitability for a 3D printer can be obtained. Can be done.

Further, the second layer 22 is made of a relatively soft material when the first layer 21 is hard, and has a function of protecting the first layer 21 so that the first layer 21 is not broken. For example, when the first layer 21 is composed of a material obtained by mixing an acrylonitrile-butadiene-styrene copolymer resin (ABS resin) with an inorganic additive (carbon fiber, glass fiber, talc, mica, nanoclay, magnesium, etc.). The second layer 22 is made of an acrylonitrile-butadiene-styrene copolymer resin (ABS resin) that does not contain an inorganic additive, and the soft second layer 22 breaks the hard and brittle first layer 21. Or suppress breakage.

Further, the second layer 22 can be made of a material containing a water vapor barrier resin, and in this case, the second layer 22 protects the first layer 21 so that the first layer 21 does not absorb moisture. Here, the water vapor barrier resin is an acrylonitrile-butadiene-styrene copolymer resin obtained by mixing, for example, a polyolefin resin such as polyethylene or polypropylene or an inorganic additive such as carbon fiber, talc, mica, nanoclay or magnesium. ABC resin) can be used. By forming the second layer 22 with the material containing the water vapor barrier resin in this way, acrylic is formed on the first layer 21 of the linear resin molded body 10 in a state where the linear resin molded body 10 is used in a 3D printer. Even when a highly hygroscopic thermoplastic resin such as a nitrile-butadiene-styrene copolymer resin (ABC resin) is used, it is possible to suppress the absorption of water vapor in the air, and the linear resin molded body 10 due to the moisture absorption. Deterioration can be suppressed. From this viewpoint, a material containing water vapor barrier resin water vapor transmission rate (g / m ² · 24h) is 30 or less, preferably 10 or less, more preferably 3.0 or less (25 ℃, 90% RH, thickness 25 μm conversion).

Further, for the second layer 22, a thermoplastic resin having a low viscosity and high fluidity and a high MFR (JIS K 7210, 210 ° C. condition) can be used. In this case, the surface appearance of the modeled object is improved, and a smooth modeled object with less unevenness can be produced. Further, even in that case, the first layer 21 is used as the core layer of the linear resin molded body (filament) to be a thermoplastic resin having an MFR relatively lower than that of the thermoplastic resin of the second layer 22. It is possible to perform molding without stretching or breaking the filament while maintaining the mechanical suitability of the printer. Specifically, the thermoplastic resin used for the second layer 22 has an MFR of 5.0 to 70 g / 10 min, preferably 10 to 60 g / 10 min. On the other hand, the thermoplastic resin used for the first layer 21 has an MFR of 0.1 to 5 g / 10 min, preferably 0.3 to 2.0 g / 10 min.

In addition, the second layer 22 can form a three-dimensional object having conductivity in the outer layer of the linear resin molded product by mixing a conductive additive such as defective carbon black. In this case, the thermoplastic resin constituting the first layer 21 has a relatively high electrical resistivity as compared with the thermoplastic resin constituting the second layer.

In this way, when the outer layer of the linear resin molded product is provided with functionality such as high viscosity and sufficient conductivity, the outer layer ratio is set to 5 to 25% to form the outer layer at the time of molding. It prevents the thermoplastic resin of the layer from hanging down and making it impossible to form the shape as planned, and the amount of carbon black or the like added to the second layer to impart conductivity is minimized. It can be suppressed.

Here, the outer layer ratio is obtained by the ratio of the four-point average value of the thickness of the second layer to be the outer layer to the average diameter of the maximum diameter and the minimum diameter in the vertical cross section of the linear resin molded product at an arbitrary position. be able to. The average thickness of the four points of the outer layer is two points of each length of the line segment overlapping the second layer located at both ends of the line segment at the maximum diameter of the linear resin molded body, and a line orthogonal to the line segment at the maximum diameter. It is calculated by averaging a total of 4 points, 2 points of each length of the line segment overlapping the second layer located at both ends of the minute. The outer layer ratio is a value expressed as a percentage by dividing the value of the four-point average thickness of the second layer, which is the outer layer, by the average diameter of the linear resin molded product.

When modeling a three-dimensional object, if the outer layer ratio of the linear resin molded product having a two-layer structure is less than 5%, the second layer, which is the outer layer after modeling, may be cut off and the first layer may be exposed. .. In this case, the function obtained by the second layer cannot be obtained. On the other hand, if the ratio of the outer layer is 35% or more, the function of the first layer on the inner layer side is not exhibited, and the function of the multiple layers cannot be obtained. By reducing the thickness of the second layer, the amount of the conductive additive such as carbon black can be suppressed.

The first layer 21 and the second layer 22 can be made of a material containing various additives such as an antioxidant and a lubricant.

The outer diameter dimensions of the first layer 21 and the second layer 22 can be appropriately set according to the required specifications. For example, the outer diameter d of the first layer 21 (see FIG. 4) is 1. It is .35 mm ± 0.2 mm, and the outer diameter D (see FIG. 4) of the second layer 22 is 1.75 mm ± 0.1 mm.

The configuration examples of the two-layer structure linear resin molded product of the present invention described so far are as follows.
(1) When the second layer is hard and the first layer is soft, the resin front strip coated with the first layer so as not to bend (2) The second layer is soft and When the first layer is hard, a linear resin molded body in which the first layer is coated with the second layer so as not to break (3) The second layer contains a water vapor barrier resin, and the second layer does not absorb moisture. A linear resin molded body in which the first layer is coated with a layer (4) The thermoplastic resin constituting the first layer has a relatively higher viscosity than the thermoplastic resin constituting the second layer, and hangs down during molding. A linear resin molded body in which the first layer is coated with the second layer with an outer layer ratio of 5 to 25% (5) The thermoplastic resin constituting the first layer is relative to the thermoplastic resin constituting the second layer. A linear resin molded body in which the first layer is coated with a second layer with an outer layer ratio of 5 to 25% in order to obtain sufficient conductivity in the outer layer of the linear resin molded body with a high electrical resistance (6). In any of the configurations 1) to (5), a linear resin molded body (ABS resin) in which the thermoplastic resin constituting at least one of the first layer and the second layer is an acrylonitrile-butadiene-styrene copolymer resin (ABS resin). 7) In any of the above configurations (1) to (6), the first layer has an outer diameter of 0.5 to 1.8 mm, and the second layer has an outer diameter of 1.1 to 2.2 mm. A linear resin molded body having a two-layer structure and having an outer layer ratio of 5 to 35%.

Next, a specific configuration example of the two-layered linear resin molded body will be described. As described above, in the linear resin molded product of the present invention having a two-layer structure, the linear resin molded product having excellent mechanical suitability and quality can be selected by selecting the material of each layer according to the application and required performance. Can be realized.

For example, when a thermoplastic resin is used alone in a linear resin molded product, the mechanical strength (rigidity) may be insufficient, but the strength can be supplemented by blending an inorganic filler.

As the inorganic filler, a fibrous material or a powder material can be used, and the material thereof is also arbitrary. Examples include carbon fiber (carbon fiber), glass fiber (glass fiber, glass wool, etc.), talc, nanoclay, calcium carbonate, magnesium carbonate, etc., which are lightweight and have a high effect of improving strength by addition. Therefore, carbon fiber is suitable.

The amount of the inorganic filler added may be set according to the required mechanical properties and the like, but is preferably 10% by mass to 40% by mass, and more preferably 20% by mass to 30% by mass. If the blending amount of the inorganic filler is less than 10% by mass, the effect (improvement of rigidity, etc.) of blending the inorganic filler may be insufficient. On the contrary, if the blending amount of the inorganic filler exceeds 40% by mass and becomes too large, the proportion of the thermoplastic resin becomes relatively too small, which may make molding difficult.

However, when an inorganic filler is mixed with the thermoplastic resin, when the linear resin molded product is made into a molded product, the fusion between the layers tends to be insufficient, and the mechanical suitability (rigidity) as the molded product is lowered. It ends up. Therefore, the periphery of the first layer containing the inorganic filler is covered with the second layer made of only the thermoplastic resin containing no inorganic filler. As a result, it is possible to realize a linear resin molded product having high mechanical strength (rigidity) and good fusion between layers.

In particular, the first layer is formed of an acrylonitrile-butadiene-styrene copolymer resin (ABS resin) containing carbon fiber, and the second layer is made of an acrylonitrile-butadiene-styrene copolymer resin (ABS resin) containing no carbon fiber. It can be said that the linear resin molded body formed in 1 is a preferable form. The mechanical strength (rigidity) is high, and the fusion between layers is also good. In addition, by blending carbon fiber, a phenomenon occurs in which the nozzle is scraped during melt extrusion in a 3D printer, but it is coated with acrylonitrile-butadiene-styrene copolymer resin (ABS resin) that does not contain carbon fiber. By doing so, scraping of the nozzle can be suppressed.

The expression "thermoplastic resin not containing an inorganic filler (not containing an inorganic filler)" here means a thermoplastic resin that does not substantially contain an inorganic filler. It is not intended to eliminate thermoplastic resins that contain an amount of inorganic filler. For example, the second layer thermoplastic resin may contain less than 3% by mass of an inorganic filler. However, the content of the inorganic filler in the thermoplastic resin of the second layer is preferably less than 1% by mass.

Further, as an example of the linear resin molded body having the above configuration (3), the first layer is formed of acrylonitrile-butadiene-styrene copolymer resin (ABS resin), and the second layer is made of polypropylene (or modified polypropylene) or Examples thereof include a linear resin molded body formed of a polyolefin (or modified polyolefin) such as polyethylene (or modified polyethylene). The acrylonitrile-butadiene-styrene copolymer resin (ABS resin) has hygroscopicity and tends to deteriorate after long-term storage or the like. Polypropylene has a barrier property against water vapor, and deterioration of the first layer (ABS resin) can be suppressed by coating with a second layer made of polypropylene. Considering the adhesiveness of the first layer to the acrylonitrile-butadiene-styrene copolymer resin (ABS resin), the second layer is preferably modified polypropylene or modified polyethylene. Here, as the modified polypropylene and the modified polyethylene, commercially available products can be used, and examples thereof include Mitsubishi Chemical Corporation, trade name Modic F534A, Mitsui Chemicals Corporation, product name Adomah SF600, and the like. it can.

In addition, a linear resin molded body in which the first layer is formed of a thermoplastic resin containing a colorant and the second layer is formed of a transparent thermoplastic resin, or the first layer is formed of a low MFR thermoplastic resin. A linear resin molded body in which the second layer is formed of a high MFR thermoplastic resin is also a specific example of a suitable linear resin molded body of the present invention. In the former case, it is possible to give a sense of quality to the appearance of the modeled object. In the latter case, the surface of the modeled object can be made into a smooth shape.

In the method of modeling a three-dimensional object by a 3D printer of the hot melt lamination method, the above-mentioned linear resin molded body is used as a modeling material, and the three-dimensional object is formed by melt-extruding the material. At this time, normally, the second layer is melt-extruded while covering the first layer, and the second layers are fused and laminated to form a three-dimensional object. If the second layer is formed of a resin having excellent heat fusion, a good fusion state can be realized, and a highly reliable three-dimensional object can be formed.

Alternatively, a three-dimensional object may be formed by melting and extruding a state in which the thermoplastic resin of the second layer and the thermoplastic resin of the first layer are mixed and laminating and depositing. For example, in the case of a linear resin molded product in which the second layer is formed of a water vapor barrier resin (for example, polypropylene), it is effective to cover the second layer with the second layer during storage to prevent deterioration. In this case, it does not necessarily have to be covered with the second layer. In such a case, for example, if a nozzle having an inner diameter significantly smaller than the wire diameter of the linear resin molded body is used, the second layer is extremely stretched and extruded in a state of being melt-mixed with the first layer. , A three-dimensional object made of mixed resin is formed.

Next, an embodiment of a method (manufacturing line) for manufacturing a linear resin molded product to which the present invention is applied will be described.

As shown in FIG. 5, the production line 30 of the linear resin molded product 1 of the present embodiment includes an extruder 31, a mold 32, a sizing device 33, a water tank 37, a fixed roller 41, an outer diameter measuring device 42, and a winding device. The taking device 43 is included.

The extruder 31 melts and kneads the raw material resin composition and continuously supplies the raw material resin composition to the mold 32, and is provided with, for example, a cylinder containing a screw, a hopper 31a for feeding the raw material, an injection nozzle, and the like. It is configured. The raw material resin composition charged from the hopper for charging the raw material is melt-kneaded by a screw in the cylinder and injected from the injection nozzle into the mold 32.

The mold 32 extrudes the molten resin from the extruder 31 in the horizontal direction, and the molten resin extruded from the extruded resin is cooled to form a linear resin molded body 10. The raw material resin composition is a mixture of a raw material resin, various additives, and the like according to the intended use, and any material can be selected.

For example, in the case of producing a linear resin molded body 10 having a two-layer structure, two types of resins made of different materials may be extruded concentrically. More specifically, in the mold 32, a line having a multi-layer structure (two-layer structure) is formed by extruding the material of the first layer 21 and the material of the second layer 22 from two outlets arranged concentrically. A continuous body of the strip resin molded body 10 is formed.

FIG. 6 shows an example of an apparatus used when manufacturing a linear resin molded product 10 having a two-layer structure. When molding the linear resin molded body 10 having a two-layer structure, the two extruders 31A and 31B are arranged so as to be orthogonal to each other. Then, for example, the raw material resin composition for forming the first layer is charged from the hopper 31a of the extruder 31A, melt-extruded into the mold 32, and the second layer is formed from the hopper 31b of the extruder 31B. The raw material resin composition of No. 1 is charged and extruded by melting into a mold 32. The raw material resin compositions extruded from the extruders 31A and 31B are merged by the mold 32, and the periphery of the first layer as the core is coated with the second layer.

As the mold 32 used when manufacturing the linear resin molded body 10 having a two-layer structure, for example, a multi-layer mold as shown in FIG. 7 may be used. The multilayer mold of this example is a combination of three mold members 32A, 32B, 32C, and each mold member 32A, 32B, 32C has central flow paths N1, N2, N3, respectively. .. The raw material resin composition is linear in these central flow paths N1, N2, N3.

Further, the mold member 32B has a circular mold portion CB inside surrounding the central flow path N2, and also has four through flow paths R1, R2, R3, R4 around the circular mold portion CB. .. The through flow paths R1, R2, R3, and R4 are each formed so as to penetrate the mold member 32B in the thickness direction. The circular mold portion CB is formed so that the central flow path N2 is formed in the center thereof and the circular surface recedes from the mold surface of the mold member 32B.

The mold member 32C has an annular flow path CR surrounding the central flow path N3, and also has a semicircular intermediate passage HR outside the annular flow path CR. This semicircular intermediate passage HR is connected to the annular flow path CR at a 180 ° symmetrical position. Further, the mold member 32C has a material supply passage X connected to one location of the intermediate passage HR. The annular flow path CR faces the through flow paths R1, R2, R3, and R4 of the mold member 32B.

In the mold 32 in which the three mold members 32A, 32B, and 32C are combined, the raw material resin composition for forming the first layer 21 is extruded from the extruder 31A, and the central flow path N3 of the mold member 32C. It is drawn out from the mold 32 through the central flow path N2 of the mold member 32B and the central flow path N1 of the mold member 32A. On the other hand, the raw material resin composition for forming the second layer 22 is extruded from the extruder 31B and supplied to the material supply passage X of the mold member 32C. The raw material resin composition supplied from here flows into the annular flow path CR through the semicircular intermediate passage HR, and each through flow path of the mold member 32B provided opposite to the annular flow path CR. It is supplied to R1, R2, R3, and R4. The raw material resin material supplied to the through flow paths R1, R2, R3, and R4 flows into the space between the mold surface of the mold member 32A and the circular mold portion CB formed in a retracted shape from the mold surface. , Covers the peripheral surface of the first layer 21 drawn from the central flow path N2 provided in the circular mold portion CB. By supplying the raw material resin material from the through channels R1, R2, R3, and R4 which are connected in an annular shape to the space, the generation of weld lines can be minimized.

The water tank 37 is formed in a long box shape along the transport direction of the linear resin molded body 10 extruded from the extruder 31. The linear resin molded body 10 is introduced into the water tank 37 from the wall at one end of the water tank 37, and is led out from the wall at the other end of the water tank 37. Water 37a for immersing the linear resin molded body 10 and cooling the linear resin molded body 10 is stored in the water tank 37.

The sizing device 33 is arranged inside the wall at one end of the water tank 37, makes the cross section of the linear resin molded body 10 sent from the extruder 31 into the water tank 37 into a perfect circle, and makes the linear resin molded body a perfect circle. It has a function of making the outer diameter dimension of 10 uniform to a predetermined dimension.

In the case of the present embodiment, vacuum suction in the sizing device 33 is a major feature. That is, by passing the sizing device 33 having a space having a circular cross section, the alignment and the wire diameter of the linear resin molded body 10 are adjusted to some extent, but that alone is not sufficient. Therefore, in the present embodiment, vacuum suction is used. We will promote this.

As shown in FIGS. 8 and 9, the sizing device 33 includes a pair of upper and lower lower members 33D and an upper member 33U, and a linear resin molded body 10 is provided on each mating surface of the lower member 33D and the lower member 33D. A plurality of semi-cylindrical surface-shaped first grooves 33a formed along the transport direction of the continuous body and passing through the linear resin molded body 10 and intersecting the first grooves 33a so as to be orthogonal to the first groove 33a (this example). Then, a second groove 33b for vacuum suction (7) arranged in parallel with each other is provided. The number of the second grooves 33b for vacuum suction is arbitrary, and may be appropriately set so that the shaping accuracy of the linear resin molded body 10 after passing through the sizing device 33 is sufficiently good. Further, the second groove 33b for vacuum suction can be provided not only in the horizontal direction but also in any direction such as a vertical direction and an oblique direction, and is appropriately provided so that the shaping accuracy is sufficiently good. You can set it.

By performing vacuum suction in the sizing device 33, a vacuum suction force acts on the linear resin molded body 10. As a result, the outer peripheral surface of the linear resin molded body 10 is attracted to the wall surface facing the space having a circular cross section of the grooves 33a provided in the lower member 33D and the upper member 33U, and the shape and diameter of the space formed by the grooves 33a are adjusted. It is shaped. As a result, the linear resin molded body 10 that has passed through the sizing device 33 has a substantially perfect circular cross section, and its diameter is substantially consistent with the set value (diameter of the space) and is constant.

The fixed roller 41 stabilizes the posture of the linear resin molded body 10 in the water tank 37 via the sizing device 33, and conveys the linear resin molded body 10 toward the winding device 43 side.

The outer diameter dimension measuring device 42 measures the outer diameter dimension of the linear resin molded body 10 cooled in the water tank 37. The take-up device 43 is arranged on the downstream side of the take-up roller 43a and a pair of upper and lower take-up rollers 43a that sandwich the linear resin molded body 10 that has passed through the outer diameter dimension measuring device 42 and convey it to the downstream side. A bobbin winder 43b having a winding shaft 43c for winding the resin molded body 10 is provided.

Next, a method of manufacturing the linear resin molded body 10 using the manufacturing line 30 will be described. The method for producing the linear resin molded product 10 includes an extrusion step, a sizing step, a cooling step, a dimensional measurement step, and a winding step.

As shown in FIG. 5, in the extrusion step, the resin pellets charged from the hopper 31a are melted in the extruder 31 and the melted resin is extruded from the mold 32. At this time, the first layer 21 is extruded and the second layer 22 is extruded so as to cover the first layer 21 to extrude the linear resin molded body 10 having a multi-layer structure. In this example, the linear resin molded body 10 having an outer diameter (indicated by reference numeral D1) of 2.2 mm is extruded from the mold 32.

In the sizing step, as shown in FIGS. 8 and 9, in the sizing device 33, the linear resin molded body 10 travels along the transport passage 35 formed by the upper and lower first grooves 33a, and at the same time, a plurality of linear resin molded bodies 10 run along the transport passage 35. By vacuum suction by the suction passages 36 formed by the upper and lower second grooves 33b, the outer diameter is formed to be uniform according to the inner diameter of the transport passage 35. In this example, when the linear resin molded body 10 having an outer diameter D1 of 2.2 mm passes through the sizing device 33, its outer diameter (indicated by reference numeral D2) is made uniform to 1.80 mm in the transport direction. ..

In the cooling step, the linear resin molded body 10 having an outer diameter (indicated by reference numeral D2) of 1.80 mm is cooled by passing through the water tank 37, and the outer diameter of the linear resin molded body 10 (indicated by reference numeral D) is cooled. Is reduced to 1.75 mm.

In the dimensional measurement step, the outer diameter of the linear resin molded body 10 is measured, and it is determined whether or not the measured value is an appropriate size. In this example, it is determined whether or not the outer diameter of the linear resin molded body 10 is within a predetermined standard width centered on 1.75 mm. When the outer diameter of the linear resin molded product 10 is outside the standard width range, each manufacturing condition is reviewed so that the outer diameter is within the standard width range.

In the winding process, when the outer diameter of the linear resin molded body 10 is within the standard range, the winding roller 43a of the winding device 43 feeds the linear resin molded body 10 to the bobbin winder 43b, and the linear resin molding is performed on the winding shaft 43c. The continuum of the body 10 is wound up. When the linear resin molded body 10 having a predetermined length is wound around the take-up shaft 43c, the linear resin molded body 10 is wound around the new take-up shaft 43c.

Since the linear resin molded body 10 manufactured by the above production line is vacuum-sucked by the sizing device 33, it has a constant wire diameter and a cross-sectional shape close to a perfect circle, which is, for example, a three-dimensional object. By using it as a raw material, it is possible to realize highly accurate modeling.

The production method of the present invention has a great effect when applied to the production of a linear resin molded product containing an inorganic filler. The linear resin molded body 10 containing the inorganic filler tends to have a larger variation in wire diameter immediately after being extruded from the extruder in the extrusion process, as compared with the linear resin molded body 10 not containing the inorganic filler. is there. Even if the linear resin molded body 10 contains such an inorganic filler and has a large variation in wire diameter after extrusion, it can be passed through the sizing device 33 in the sizing step to obtain a constant cross-sectional shape close to a perfect circle. can do. That is, when the linear resin molded body 10 contains an inorganic filler, a higher effect can be obtained for stabilizing the wire diameter by vacuum suction in the sizing device 33. Here, examples of the inorganic filler include the inorganic fillers listed in the specific configuration example of the above-mentioned two-layered linear resin molded product.

Hereinafter, specific examples of a method for producing a linear resin molded product to which the present invention is applied will be described based on experimental results.

Example 1
The molten resin melt-kneaded by an extruder was supplied to the die core for injection, and then drawn out from a mouthpiece provided on the die core. After adjusting the wire diameter and alignment to some extent with this mouthpiece and shaping it into a linear resin molded body, sizing is provided at the inlet of the water tank to be cooled and solidified, and the final cross-sectional shape of the linear resin molded body is provided in this sizing portion. (Wire diameter and alignment) were adjusted. At that time, the shape was shaped by vacuum suction in the sizing part, cooled and solidified in a water tank, and wound by a winder. Further, the linear resin molded body sent out from the winder was wound on the bobbin.

Comparative Example 1
It is the same as Example 1 except that the sizing is not provided at the inlet of the water tank to be cooled and solidified.

Evaluation The linear resin molded products prepared in Example 1 and Comparative Example 1 were evaluated by measuring the wire diameter and linearity.
(Wire diameter)
The wire diameter was measured with a digital caliper (NTD25-20CX manufactured by Mitutoyo Co., Ltd.) using the resin linear bodies molded in Example 1 and Comparative Example 1. After allowing to stand at room temperature of 23 ° C. for 1 day, the average value of the longest diameter and the shortest diameter of the linear resin molded product measured at 10 measurement positions at equal intervals of 10 cm was calculated.
(linear)
The alignment of the resin striatum was measured by observing the cross-sectional shape using a digital microscope (VHX-900 manufactured by Keyence Co., Ltd.) using the resin striatum molded in Example 1 and Comparative Example 1. The diameters of the longest part and the shortest part of the cross section of 10 points were measured, and the roundness was calculated from the following equation.
Roundness (%) = (shortest diameter / longest diameter) x 100

The measurement results for Example 1 are shown in Table 1. Table 2 shows the measurement results for Comparative Example 1.

(Confirmation of effect)
As is clear from the measurement results shown in Tables 1 and 2, it was confirmed that Example 1 showed good performance in wire diameter and linearity. For example, for linearity (roundness), 98% or more (98 to 100%) is preferable, but Example 1 sufficiently clears this condition. On the other hand, in Comparative Example 1, it was confirmed that both the wire diameter and the linearity had a large variation, and good performance was not obtained as a resin linear body.

As is clear from the above evaluation results, it is possible to manufacture a linear resin molded product having a constant wire diameter and a cross-sectional shape close to a perfect circle by vacuum suction in the sizing portion. By using it as a raw material for a three-dimensional object, it is possible to realize highly accurate modeling.

Although the embodiments to which the present invention has been applied have been described above, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. It is possible.

10 Strand resin molded body 21 1st layer 22 2nd layer 30 Manufacturing line 31 Extruder 32 Mold 33 Sizing device 37 Water tank 42 Outer diameter dimension measuring device 43 Winding device d 1st layer outer diameter D 2nd layer Outer diameter

Claims (4)

A method for manufacturing a linear resin molded product used in a hot melt lamination type 3D printer.
The melt-kneaded resin material is continuously extruded from an extruder via a mouthpiece, and the extruded linear resin molded product is passed through a cooled sizing device while being vacuum-sucked, and then cooled and solidified and wound up. As a feature,
The sizing device is a method for manufacturing a linear resin molded product, which has a space having a circular cross section and has a plurality of vacuum suction grooves on a surface facing the space . The method for producing a linear resin molded product according to claim 1, wherein the sizing device is arranged in a water tank. The linear resin molded body includes a first layer containing a thermoplastic resin and a second layer that covers the first layer and contains a thermoplastic resin and has physical properties different from those of the first layer. The method for producing a linear resin molded body according to claim 1 or 2, which is characterized. The method for producing a linear resin molded product according to any one of claims 1 to 3, wherein the linear resin molded product contains an inorganic filler.

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