JP6902197B2 - A mold for wood flow molding, a mold system for wood flow molding using the same, and a method for manufacturing a molded product made of a plant-based material. - Google Patents

Description

The present invention relates to a mold suitably used for fluid molding of a plant-based material such as wood or bamboo, and more specifically, a plant-based material impregnated with an additive such as a resin is put into a heating container. Precisely finished surface by flow molding, which causes a wood flow phenomenon by applying high temperature and high pressure of 10 MPa or more and 100 ° C or more by punch pressurization, and flows into a mold having an arbitrary cavity shape. The present invention relates to a mold for obtaining a good plant molded product having the same surface accuracy as that of the above, a mold system for wood flow molding using the mold, and a method for producing a molded product of a plant-based material.

The present invention has a problem on the mold side that mold damage such as galling and deformation of the sliding portion of the mold occurs in the conventional wood flow molding using a plastic mold, and a high friction state due to burrs and the like. In addition to solving the problem on the molded product side that a fluid molded body with good surface texture cannot be obtained due to the increase in molding load caused by the above and the deterioration of the cavity surface texture, reduction of the molding load by solving the above problems and problems, It provides a mold for wood flow molding that facilitates burrs suppression, shaping into complex shapes, shaping into ultra-thin molding, and the like.

Woody fluid molding is a method for molding a plant-based material according to Patent Document 1, in which a plant-based material such as wood or bamboo is molded by applying heat and pressure in a swollen / softened state using an arbitrary mold. Compared to the method of compressing and densifying by closing the lumen of wood cells to change the shape, deformation is given by the position change due to the slip phenomenon between wood cells, so a larger amount of deformation can be given. .. As a result, plastic working of an arbitrary shape wood-based material, which was not possible only by conventional compression processing, can be realized, and damage to fibrous wood cells can be suppressed. It can have a fiber reinforcing effect. Further, as described in Patent Document 2, a method of using various additives for swelling / softening and improving various physical properties of a molded product has also been developed. Among them, a method of performing flow molding using a resin-impregnated wood-based material using a resin that can permeate wood cells and can be impregnated with a solvent has been put into practical use.

Wood flow molding is a type of plastic processing using a mold. In particular, wood materials are natural polymer materials consisting of cellulose, hemicellulose, and lignin, and when additives are used, phenol resin, melamine resin, urea resin, etc. are used. Thermoplastic resins such as thermosetting resins, acrylic resins, styrene resins, and urethane resins are preferably used. Therefore, various plastic working methods have been diverted using plastic dies.

However, when trying to flow-mold a wood material or a resin-impregnated wood-based material in which a wood material is impregnated with a resin using a general-purpose plastic mold, there is a large difference in hardness and strength at the tissue cell level. Mold damage and cavity wear due to insufficient strength of the mold material, which is thought to be caused by a special fluid molding material, uneven deformation of the cavity, and mold corrosion due to corrosive components including acid generated from wood materials at high temperature and high pressure. , Excessive burrs due to peculiar deformation anisotropy, galling of the sliding portion mold, increase in molding load, etc. occur, and it becomes difficult to obtain a good wood flow molded body.

In Patent Document 3, Patent Document 4, and Patent Document 5, the applicant and the like have proposed a method and apparatus for manufacturing a plate material by wood flow molding, a method for manufacturing a long member by wood flow molding, and the like. In these woody flow moldings, pre-hardened plastic mold steel (Rockwell hardness HRC40) is mainly used, and the above-mentioned problems have been clarified.
The present inventors have identified the cause of the above-mentioned problems in an earnest study using a metal forging die in order to search for a good embodiment of wood flow molding. It is the proper adjustment of the hardness of the mold base, the proper adjustment of the coating type and conditions that maintain good lubrication between the mold surface and the wood material under high temperature and high pressure, and at the same time realize the corrosion resistance, and the sliding part. It was found that it is important to set an appropriate clearance amount and surface roughness.

Japanese Patent Application Laid-Open No. 2008-036941 JP 2010-155394 JP 2012-161932 JP 2012-161933 International Publication No. 2014/010579 International Publication No. 2009/121159

Under such circumstances, the present inventor can surely solve the problems of the prior art in view of the prior art, and in the wood flow molding of the resin-impregnated wood-based material, the temperature is 100 to 200 ° C. Formability by properly setting the coating type and coating conditions and substrate hardness that maintain a good frictional state under a surface pressure of 10 to 400 MPa, the amount of clearance that suppresses the occurrence of burrs on sliding parts, and the surface roughness of the cavity. In addition, it has become possible to repeatedly manufacture a flow-molded body having improved mold releasability and good surface accuracy, and to manufacture a wood flow-molding mold capable of reducing damage and corrosion of the mold and cavity.

The present invention provides a wood flow molding die for industrially producing a good wood flow molded product, a wood flow molding die system using the same, and a method for producing a molded body made of a plant-based material. Is the purpose.

In order to achieve the above object, the wood flow molding die of the present invention is a flow molding in which pressure and heat are applied to a plant-based material such as wood and bamboo to cause a mutual positional change of wood cells to cause deformation processing. The base material is an alloy tool steel having a Rockwell hardness of HRC55 or more, and has a chromium nitride film on the surface in contact with a plant-based material during molding, and the surface roughness Ra thereof is within 0.1 μm. It is characterized by having a mirror-finished surface of No. 1 and having a friction coefficient of 0.2 or less with a plant-based material in a softening temperature range in a non-lubricated state under a pressure range of 10 to 400 MPa.

Further, in the wood flow molding mold system of the present invention using the wood flow molding mold, the clearance of the sliding portions of the plurality of molds according to claim 1 of the wood flow molding mold system is 0.015 mm. It is characterized by the following.

In this case, at least one of the plurality of molds is a cavity mold, which is characterized by having a mechanism for controlling its hermeticity.

Further, in the method for producing a molded product made of the plant-based material of the present invention using the above-mentioned wood flow molding mold system, the cavity surface temperature is 100 to 200 ° C. and a punch load is obtained by using the above-mentioned wood flow molding mold system. Contains a thermoplastic or thermosetting resin having a smooth surface texture with a surface roughness Ra in the range of 0.025 to 1.6 μm, which is molded under molding conditions with a surface pressure of 10 to 400 MPa and a maximum punching speed of 2 mm / s. It is characterized by producing a molded product made of the plant-based material of.

According to the present invention, the following effects are achieved.
(1) Prevents mold damage such as galling and deformation of the sliding portion of the mold, which has been a problem in conventional wood flow molding using a plastic mold.
(2) It is possible to obtain a fluid molded article having good surface properties by preventing an increase in molding load caused by a high friction state due to burrs caused by the peculiar flow anisotropy of plant-based materials and deterioration of cavity surface properties. it can.
(3) It is possible to provide a wood flow molding die that facilitates reduction of molding load, suppression of burrs, shaping into complex shapes, shaping into ultrathin molding, and the like.
(4) It is possible to improve the life of the mold and industrially produce a good wood fluid molded product.
(5) Since the plant-based material used in the present invention is made from a plant-based material which is a recyclable resource, it can be a fundamental solution to the resource problem and the waste problem.

An example of a mold structure applied to wood flow molding is shown. The change in the surface condition of the die base material in the flat plate press test assuming wood flow molding is shown. The evaluation result of corrosiveness with and without tool coating in the flat plate press test assuming wood flow molding is shown. The method of measuring the coefficient of friction is shown. The effect of the tool surface roughness on the changing behavior of the friction coefficient (non-lubrication condition) in the sliding test of the tool and the resin-impregnated wood material is shown. The evaluation results of the surface appearance and roughness of the sample after the sliding test are shown. The load-stroke diagram at the time of the flat plate press test assuming wood flow forming is shown. The effect of the tool surface roughness on the deformation state (appearance of the molded body, area expansion rate, compressibility) and surface texture (appearance, roughness) of the molded body obtained by the flat plate press test assuming wood flow molding is shown. .. The effect of clearance on mold galling (wear) is shown.

As the mold conditions for satisfactorily performing wood flow molding, considering the fiber structure peculiar to wood material, a large variation in its strength, and corrosive gases and substances during heating and pressurization, it is possible to use wood material. Optimization of the mold surface as an interface, selection of an appropriate base material for holding the surface, optimization of mutual positional conditions and cavities for arranging and operating a plurality of these molds. After configuring the sealing mechanism as a mold system, it is important to optimize the molding conditions using this wood flow molding mold.

The mold in the present invention includes a container part that supplies wood-based materials, a punch that applies a load to the wood-based material, a die that adjusts the shape of the fluid wood-based material, and a fluid wood-based material into the final product shape. Refers to a cavity to be shaped.
A typical wood flow molding method, specifically, for example, a mold configuration based on forward extrusion, backward extrusion, lateral extrusion, injection molding / transfer molding, and closed forging is shown in FIG. The flow molding is carried out using a mold composed of a container portion 2 for supplying a resin-impregnated wood material as a material, a punch 1 for applying pressure to the wood material, a die 3 having a required shape, and a cavity portion 4. It is said. In these mold configurations, when each mold is combined, a boundary is generated, and when there is a relative position change (movement), a sliding surface indicated by a shaded portion is generated. When plastic or metal is used as the material, the clearance at the sliding portion is set according to the punch diameter and the inner diameter of the container (0.5 to 1.0%). This value can give a good load to the material filled in the container by performing a guide function while maintaining good sliding with the punch outer diameter by the inner diameter of the container, and when the clearance becomes small. Seizure may occur in the sliding area, leading to mold breakage. Further, in the case of having a cavity as shown in FIGS. 1 (e) and 1 (f), when the cavity is completely sealed, the mold is damaged due to the excessive internal pressure of the cavity, and the wood material at the time of flow molding is released. It causes surface roughness, unfilling, and deterioration of physical properties due to the generation of volatile components. On the other hand, when a relief hole or the like is provided in order to avoid a sealed state, if the cross-sectional area is excessive, many burrs are generated and the molded product is poorly filled with material due to insufficient back pressure. ..

The present invention is a wood flow forming die obtained by forming a mirror-finished inner surface of a container, a punch surface, and a cavity by applying a chromium nitride coating to an alloy tool steel whose hardness has been adjusted by heat treatment.
Further, it is preferable that the alloy tool steel is equivalent to SKD11 and the Rockwell hardness is HRC55 or more.
The Vickers hardness of the chromium nitride film is preferably 1600 or more.
Further, the surface roughness of the chromium nitride film is preferably Ra 0.1 μm or less.
The thickness of the chromium nitride film is preferably 2 μm or more.
Further, it is preferable that the friction coefficient between the surface of the chromium nitride film and the wood material under the molding conditions is 0.2 or less.
Further, it is preferable to provide the above-mentioned chromium nitride film on the container, the punch, the sliding surface between the cavities, and the place where the contact with the wood material occurs, which constitutes the mold.
Further, the clearance amount between the container serving as the sliding portion and the punch or the like is preferably 0.015 mm or less.
It is preferable that the cavity is provided with a mechanism for controlling the closed state.

According to the present invention, for example, reducing the molding load during flow molding, reducing the amount of impregnated resin of the wood material used, producing a more complicated shape or thinner wood flow molded body, cavities, etc. It is possible to prevent breakage, wear and corrosion and improve the life of the mold.

Here, in the production of a molded product made of a plant-based material, a cavity surface temperature of 100 to 200 ° C., a punch load surface pressure of 10 to 400 MPa, and a maximum punch speed of 2 mm / It can be molded under the molding conditions of s.
This makes it possible to produce a molded product made of a plant-based material containing a thermoplastic or thermosetting resin having a smooth surface texture with a surface roughness Ra in the range of 0.025 to 1.6 μm.

Here, the Rockwell hardness described in the present invention was measured at room temperature based on JIS Z 2245, and the surface roughness was measured based on JIS B 0601.

Next, the present invention will be described in more detail based on examples showing the basis.

(Mold base material)
In order to clarify the preferred mold base material for fluid molding of wood materials impregnated with resin, a base material for molds for plastics (aluminum alloy A5052P, NAK 55 made by Daido Special Steel), a base material for forming metal materials, die steel ( Using a flat plate tool made of SKD 11), a single plate of phenolic resin-impregnated hinoki as a resin-impregnated wood-based material (weight increase rate WPG: 40% = resin content 28.5%, φ13.2 mm x thickness 4 mm), The surface of the tool before and after pressing was observed under the conditions of a material temperature: 140 ° C. and a final press load of 110 kN (surface force: 210 MPa). The result is shown in FIG. In aluminum alloys, which are widely used as base materials for plastic dies, dents along the shape of resin-impregnated wood-based materials were formed on the surface of flat plate tools after pressing. Even in NAK55, which has a higher hardness than the aluminum alloy, although the region is smaller than that of the aluminum alloy base material, dents are formed along the hard parts such as fiber cells of the resin-impregnated wood-based material that has undergone flow deformation. It was found that this requires measures assuming that a local increase in surface pressure will occur in flow molding. In the case of die steel whose hardness was adjusted by heat treatment, dents on the tool surface seen in the plastic mold base material were not observed at HRC55 and above.

(Effect of film type)
In order to examine the influence of the type of coating film on the wood flow molding die, the releasability after the flat plate heat compression test is determined by the releasability due to the difference in the tool surface treatment in the flat plate press test assuming wood flow molding. evaluated. The good or bad of the releasability is 〇 when it leaves as it is in the heated state after decompression, Δ when it separates due to the difference in the coefficient of thermal expansion after cooling the tool after compression, and × when it does not separate even after cooling. .. The results are shown in Table 1.

As shown in Table 1, in the absence of the coating film, the wood material that flowed by heating and compressing adhered to the tool, and it was difficult to release the mold even after cooling. On the other hand, when the coating film was provided, the releasability was improved, but among them, the film released as it was in the heated state was chromium nitride, which showed very good results. From the viewpoint of heat resistance, abrasion resistance, and durability, this coating may be used as a die for pressing a thin metal plate or a die for plastic, but in wood flow molding, it is used for metal and plastic. Good results could not be obtained in terms of mold releasability with respect to other DLC and TiCN coatings suitable for.

(Effect of coating film)
Chromium nitride-based coatings have traditionally been effective in reducing wear on cutting edges and improving wood cutting surface properties as coatings for cutting tools, especially rotary cutting chips, in wood processing (Patent Document 6, Wood). Journal of the Society Vol.54 (No.5), p.263-271).
In order to examine the effect of the coating film on the wood flow molding die, a flat plate tool in which a chromium nitride film is physically deposited on SKD11, an alloy tool steel whose hardness is adjusted to HRC55 or higher, to a thickness of 5 μm, and 11 SKDs without a film. Using a flat plate tool that has only been polished with wood, a single plate of hinoki impregnated with phenol resin (weight increase rate WPG: 40% = resin content 28.5%, φ13.2 mm x thickness 4 mm), work material temperature: The surface of the tool before and after being continuously pressed 20 times under the condition of surface force calculated at 140 to 160 ° C. and the initial area of the single plate: 10 MPa was observed. As shown in FIG. 3, the surface texture of the tool coated with the chromium nitride coating did not change before and after the press experiment, whereas it was clear when the surface condition of the base material without the chromium nitride coating remained. Corroded parts (craters in the black part) occurred.

(Effect of surface roughness)
In order to investigate the effect of surface roughness that can be suitably used as a mold for wood flow molding, the surface of the tool is physically vapor-deposited with a chromium nitride film to a thickness of 5 μm on alloy tool steel SKD11 whose hardness is adjusted to HRC55 or higher. A sliding test of a phenol resin impregnated hinoki material was carried out under a vertical surface pressure of 10 MPa as shown in FIG. 4 using a flat plate tool (Ra: 0.25, 0.03) subjected to two types of surface treatments having different degrees of friction. And the coefficient of friction was measured. As shown in the result of FIG. 5, there was a large difference in the coefficient of friction during sliding depending on the surface roughness of the tool. When Ra was 0.25, the coefficient of friction was about 0.4, which was a large sliding resistance. On the other hand, by setting Ra to 0.0 4 , the coefficient of friction can be suppressed to 0.2 or less, and the sliding resistance can be reduced. This greatly contributes to preventing an increase in the load during molding.

(Changes in surface texture of wood due to sliding)
FIG. 6 shows the results of observing the surface texture of the sliding portion of the phenol resin-impregnated cypress material after the sliding test. The properties differed greatly depending on the degree of surface roughness Ra, and the surface of the cypress wood slid under the tool condition of Ra was 0.25, and the wood fibers were broken and peeled off, resulting in a hangnail state. As a result, the surface roughness of the wood material was 2.8 in Ra. On the other hand, Ra the slide has been wood material in 0.0 4 tool conditions, disruption of the wood fiber, delamination is a good condition hardly observed, Ra about 1.2 (good mechanical finish Surface equivalent) was shown.

(Impact on molding load and surface texture of molded product)
In order to investigate the effect of surface roughness that can be suitably used as a mold for wood flow molding, the tool surface is finished by physically depositing a chromium nitride film with a thickness of 5 μm on alloy tool steel SKD11 whose hardness is adjusted to HRC55 or higher. Using a flat plate tool (Ra: 0.25, 0.03) that has been subjected to two types of surface treatment with different degrees, a single flat plate impregnated with phenol resin (weight increase rate WPG: 40% = resin content 28.5) %, Φ13.2 mm x thickness 4 mm), a flat plate press test was performed under the conditions of a work material temperature: 140 ° C., a maximum compressive load of 110 kN (surface force calculated based on the initial area: about 800 MPa), and a press speed of 10 mm / min. It was. As shown in the load-stroke diagram of FIG. 7, there was a large difference in the flow start load during molding depending on the tool surface roughness. The flow start load (load at the time point ▼ in the figure) was about one-third when Ra was 0.03 as compared with when Ra was 0.25, and the molding load was greatly reduced. FIG. 8 shows the results of observing the deformed state and surface texture of the wood flow molded product obtained after the test. The area expansion rate and the thickness change rate of the molded product were larger when Ra was 0.03 than when Ra was 0.25, and better moldability was exhibited when the surface roughness was smaller. Further, it was found that the surface roughness of the obtained molded product was affected by the tool surface condition, and if the tool surface roughness was set to Ra 0.03, the surface roughness Ra of the molded product produced thereby was 0. The value corresponding to the precision finished surface of about 2 was shown.

(clearance)
In the case of wood flow molding, with the normal clearance setting, the resin-impregnated wood material partially or locally flows back into the clearance when the punch is loaded, so that a good guide function cannot be achieved and the punch is very small. Since the load continues in the tilted state, seizure occurred when the clearance was 0.25 mm as shown in FIG. On the other hand, it was found that setting a smaller clearance solves this problem. By setting the diameter to 0.015 mm (15 μm), which is about the same as or smaller than the diameter of the wood fiber, which is the flow unit of the resin-impregnated wood material, the backflow of the wood material under punch load is prevented and good punching is performed. We found that the load can be continued.

In the present specification, the "wood material" is not particularly limited, and specifically, for example, softwood, hardwood, and bamboo are exemplified as particularly suitable materials.

As described in detail above, the present invention prevents mold damage such as galling and deformation of the sliding portion of the mold, which has been a problem in wood flow molding using a conventional plastic mold, and is a plant-based material. A flow-molded article having good surface properties can be obtained by preventing an increase in molding load and deterioration of cavity surface properties caused by a high friction state due to burrs and the like caused by peculiar flow anisotropy. Furthermore, since it is possible to provide a mold for wood flow molding that facilitates reduction of molding load, suppression of burrs, shaping to complex shapes, shaping to ultra-thin molding, etc., the life of the mold is improved. Therefore, good wood flow molded products can be industrially produced. Then, the industrial use of fluid molding using plant-based materials, which are recyclable resources, as a raw material can provide a fundamental solution to the resource problem and the waste problem.

1 Punch 2 Container part 3 Die 4 Cavity part

Claims (4)

The plant-based material, a mold used in the flow molding of performing deformation processing and brought resulting position change of the wood cells mutually apply pressure and heat, in the substrate Rockwell hardness HRC55 or more alloy tool steel Yes, it has a chromium nitride film on the surface in contact with the plant material during molding, has a mirror-finished surface with a surface roughness Ra of 0.1 μm or less, and softens in a non-lubricated state under a pressure range of 10 to 400 MPa. A mold for wood flow molding characterized in that the friction coefficient with a temperature range plant-based material is 0.2 or less. A mold system for wood flow molding, wherein the clearance of the sliding portions of the plurality of molds according to claim 1 is 0.015 mm or less. The mold system for wood flow molding according to claim 2, wherein at least one of the plurality of molds is a cavity mold and has a mechanism for controlling the airtightness thereof. Using the wood flow molding mold system according to claim 2 or 3, molding is performed under molding conditions of a cavity surface temperature of 100 to 200 ° C., a punch load surface pressure of 10 to 400 MPa, and a maximum punch speed of 2 mm / s. From a plant-based material characterized by producing a molded product made of a thermoplastic or thermosetting resin-containing plant-based material having a smooth surface texture with a surface roughness Ra in the range of 0.025 to 1.6 μm. A method for manufacturing a molded product.

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