Manufacturing method for resin molded objects

Abstract

This invention provides a method for manufacturing resin molded objects that can easily produce high-quality resin molded objects of desired dimensions. [Solution] A manufacturing method for manufacturing a three-dimensional resin molded object W, comprising: a molding step of forming a rough molded object W1 by layering resin material using a 3D printer; and a removal step of removing unnecessary parts of the rough molded object W1 to form a resin molded object W.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a resin molded product.

Background Art

[0002] Regarding resin molded products used in various products, for example, when producing a prototype during the product development stage, it is usually the case that an existing resin material, such as a resin material formed into a plate shape or a rod shape by extrusion molding or the like, is cut to produce it.

[0003] However, in the method of cutting a plate-shaped resin material, generally, the types of commercially available cutting resin materials are few, and the types and colors of resins that can be used for prototyping are limited. Also, the shapes of generally commercially available resin materials are plate materials or rod materials, etc., and resin materials that can produce and prototype relatively large articles by cutting are extremely limited. Therefore, in sample production by resin cutting, the types and colors of resins cannot be freely selected as materials, and in many cases, it is impossible to produce with the material intended for mass production or the material to be considered for mass production. As a result, it is impossible to manufacture a prototype for evaluating the performance of a resin molded product when mass-produced and commercialized, which has become an obstacle in manufacturing mass-produced products and commodities by resin molding.

[0004] Due to such a situation, when it is necessary to appropriately evaluate the performance such as the strength of a resin molded product when mass-produced and commercialized, a mold is produced in the same way as mass production, and a prototype is injection-molded using the resin material planned to be used.

[0005] For example, a method of molding a prototype of the same material as a regular product at a short delivery time and at a low cost by using a simple mold is known (for example, see Patent Document 1).

[0006] However, the method disclosed in Patent Document 1 still involves the production of a mold, just as in the case of mass production and commercialization, which takes more time, cost, and effort compared to, for example, prototyping by cutting. Furthermore, in such injection molding methods, there is a limit to the size of the resin material that can be molded because voids (so-called air pockets) inevitably form inside the resin when the molten resin is cooled in the mold. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2014-65152 [Overview of the project] [Problems that the invention aims to solve]

[0008] Therefore, one of the objectives of the present invention is to provide a method for manufacturing resin molded objects that can easily produce resin molded objects of a desired size and of good quality. [Means for solving the problem]

[0009] A method for manufacturing a resin molded object according to an embodiment of the present invention is a method for manufacturing a three-dimensional resin molded object, comprising: a molding step of forming a rough molded object by laminating resin material using a molded object manufacturing apparatus; and a removal step of forming a resin molded object by removing unnecessary parts of the rough molded object.

[0010] In the above-described method for manufacturing resin-molded objects, the object manufacturing apparatus may be a fused deposition modeling (FDM) 3D printer.

[0011] In the above method for manufacturing resin molded objects, the resin material may be a pelletized thermoplastic resin.

[0012] In the above method for manufacturing resin molded objects, the molding process may involve moving the nozzle of the molded object manufacturing apparatus along a space-filling curve on an arbitrary two-dimensional plane with a finite depth while extruding the resin material.

[0013] In the above method for manufacturing resin molded objects, the molding process may involve extruding the resin material while moving the nozzle of the molded object manufacturing apparatus in a closed curve.

[0014] In the above method for manufacturing resin molded objects, the molding process may involve extruding the resin material while moving the nozzle of the molded object manufacturing apparatus in a single continuous motion.

[0015] In the above method for manufacturing resin molded objects, the molding process may involve overlapping the resin materials to create overlapping portions.

[0016] In the above method for manufacturing a resin molded product, the resin material may be extruded in the molding process while continuously moving the nozzle of the molding apparatus in the layering direction.

[0017] In the above method for manufacturing a resin molded object, the molding process may involve sequentially layering resin material along the circumference of the rough molded object.

[0018] In the above method for manufacturing resin molded objects, the removal step may involve cutting the surface of the rough molded object to create a cut surface.

[0019] In the above method for manufacturing resin molded objects, the unnecessary parts may be layer lines.

[0020] In the above method for manufacturing a resin molded object, the resin molded object may also be a resin block for machining.

[0021] In the above method for manufacturing a resin molded object, the resin molded object may also be a resin block for machining.

[0022] In the above method for manufacturing resin molded objects, the resin molded object may be any of the following: a rectangular prism, a cube, a cylinder, a sphere, a pyramidal pyramid, or a cone.

[0023] In the above-described method for manufacturing a resin-molded object, the resin-molded object may be cylindrical. [Effects of the Invention]

[0024] According to an embodiment of the present invention, a resin molded object having a desired dimension with good quality can be easily manufactured.

Brief Description of the Drawings

[0025] [Figure 1] It is a front view schematically showing a 3D printer of a hot melt lamination method which is a molding apparatus used in a resin molded object manufacturing method according to an embodiment of the present invention. [Figure 2] (a) is a perspective view showing an example of shaping a rough molded object by a molding apparatus of the resin molded object manufacturing method, and (b) is a perspective view showing an example of shaping a resin molded object manufactured through a removal process for the rough molded object of (a). [Figure 3] It is a plan view showing an example of 3D shaping data of a concentric annular shape in the shaping process of the resin molded object manufacturing method. [Figure 4] It is a plan view showing an example of setting a reference line for a scanning path configuration of a nozzle of a 3D printer in the 3D shaping data of FIG. 3. [Figure 5] (a) is a plan view showing an example of a setting of a scanning path of a nozzle of a 3D printer in the 3D shaping data of FIG. 4, and (b) is a plan view showing another setting example. [Figure 6] (a) is a plan view showing an example of a layer shaped based on the 3D shaping data of FIGS. 3 and 4, (b) is a cross-sectional view of (a), and (c) is an enlarged view of a part of (b). [Figure 7] It is a cross-sectional view of the layers laminated in FIG. 5. [Figure 8] (a) is a cross-sectional view showing an example of the rough molded object of FIG. 2(b), and (b) is an enlarged view of a part of (a). [Figure 9] (a) is a photograph showing an example of shaping a rough molded object by a molding apparatus of the resin molded object manufacturing method, (b) is a photograph showing an example of shaping a resin molded object manufactured through a removal process for the rough molded object of (a), and (c) is a photograph showing an example of shaping a resin molded object manufactured by further advancing the removal process for (b). [Figure 10](a) is a plan view showing another example of the scanning path settings for the nozzle of the same 3D printer, (b) is a plan view showing yet another example of the scanning path settings for the nozzle of the same 3D printer, and (c) is a plan view showing yet another example of the scanning path settings for the nozzle of the 3D printer. [Figure 11] (a) is a plan view showing yet another example of the scanning path of the nozzle of the same 3D printer, and (b) is a plan view showing yet another example of the scanning path of the nozzle of the same 3D printer. [Figure 12] (a) is a photograph showing an example of a rough molded object produced by the molded object manufacturing apparatus of the same resin molded object manufacturing method based on the scanning path in Figure 11(b), and (b) is a photograph showing an example of a resin molded object produced after the rough molded object in (a) has undergone a removal process. [Figure 13] This is a plan view showing yet another example of the scanning path settings for the nozzle of the same 3D printer. [Figure 14] Figure 13 is a photograph showing an example of a rough-formed object produced by the resin molding apparatus of the same molding method based on the scanning path. [Figure 15] (a) is a plan view showing yet another example of the scanning path of the nozzle of the same 3D printer, and (b) is a plan view showing yet another example of the scanning path of the nozzle of the same 3D printer. [Figure 16] This is a plan view showing yet another example of the scanning path settings for the nozzle of the same 3D printer. [Figure 17] Figure 16 is a photograph showing an example of a resin-molded object produced by the same resin-molded object manufacturing apparatus based on the scanning path. [Modes for carrying out the invention]

[0026] One embodiment of the present invention will be described with reference to the drawings.

[0027] In Figure 1, 1 is a fused deposition modeling (FDM) 3D printer, which is a device for manufacturing molded objects. This FDM 3D printer (hereinafter sometimes simply referred to as "3D printer 1") is a molding machine that sequentially builds up layers of resin material, which is a molding material melted by heat, one layer at a time, based on 3D modeling data, to manufacture a three-dimensional resin molded object W.

[0028] The resin material used in 3D printer 1 is a thermoplastic resin, including general-purpose plastics, engineering plastics, super engineering plastics, reinforced resins, recycled plastics, biomass plastics, and biodegradable plastics. More specifically, examples include PVC, POM, PBAT, AAS, PS, PLA, PBS, PE, plant fiber-reinforced PLA, plant fiber-reinforced PBS, ABS, glass fiber-reinforced ABS, carbon fiber-reinforced ABS, PP, glass fiber-reinforced PP, basalt fiber-reinforced PLA, basalt fiber-reinforced ABS, basalt fiber-reinforced PP, basalt fiber-reinforced PC, basalt fiber-reinforced PE, PVC carbon fiber-reinforced PP, PC, glass fiber-reinforced PC, PC·ABS, ASA, TPE, TPU, cellulose acetate, PA, PETG, etc. The resin material can be in any form, such as filament or powder, but pellets are preferred. Furthermore, 3D printer 1 is, for example, a single-nozzle head specification, and only one type of resin is required for printing; a support resin (such as a water-soluble resin) is not necessary.

[0029] The 3D printer 1 comprises, for example, a box-shaped main body 3 having a build chamber 2 inside, a build head 4 that can move in the X-axis direction (horizontal direction, left to right) and the Z-axis direction (vertical direction, height) within the build chamber 2, and a build table 5 that can move in the Y-axis direction (horizontal direction, front to back) within the build chamber 2.

[0030] Furthermore, since the build head 4 is movable in the X and Z axes and the build table 5 is movable in the Y axis, the build head 4 moves in three dimensions relative to the build table 5 (as will be described later, the 3D printer 1 is not limited to the configuration shown in Figure 1, and any configuration in which the build head 4 moves in at least three dimensions relative to the build table 5 is acceptable).

[0031] Furthermore, the 3D printer 1 includes a first drive unit 6 that moves the build head 4 in the X-axis and Z-axis directions within the build chamber 2, a second drive unit 7 that moves the build table 5 in the Y-axis direction within the build chamber 2, and a control unit 8 that controls both drive units 6, 7, etc., based on 3D build data such as STL data.

[0032] Then, based on the control by the control unit 8, the build head 4 moves in three dimensions relative to the build table 5, and resin (molten resin) is extruded from the nozzle 11 of the build head 4 during this movement. As this extruded resin hardens and solidifies, the resin is layered on the build table 5, creating a three-dimensional rough shape W1 of the desired form.

[0033] The rough molded object W1 is ultimately used to manufacture the target resin molded object W. In other words, the rough molded object W1 is first fabricated using the 3D printer 1, and then the unnecessary parts of the rough molded object W1 are removed to obtain the target resin molded object W.

[0034] Here, the build head 4 of the single-nozzle head fused deposition modeling 3D printer 1 is, for example, of the fused resin extrusion type, and has a single nozzle 11 that extrudes resin melted by heat from a heating means (not shown) inside the build head 4.

[0035] In other words, the resin, heated and melted by a heating means such as a heater (not shown), is extruded by an extrusion means (not shown) such as a gear inside the build head 4, and discharged (discharged) from the discharge port of one nozzle 11 for resin material discharge in the direction of the central axis of the discharge port, for example, downwards. Note that the heating means and extrusion means may be provided outside the build head 4 instead of inside the build head 4.

[0036] Next, we will describe a method for manufacturing a resin-molded object, such as the three-dimensional resin-molded object W shown in Figure 2(b), using the fused deposition modeling (FDM) 3D printer 1 described above.

[0037] The resin molded object W is a resin block for machining, particularly for cutting, and in this embodiment, it has simple (primitive) shapes such as a rectangular parallelepiped, a cube, a column (cylinder, polygonal prism), a tube (cylinder, polygonal tube), a cone (cone, polygonal pyramid), a truncated cone (truncated cone, truncated polygonal pyramid), or a sphere. In the example shown in Figure 2(b), the resin molded object W is a thin, rectangular parallelepiped that is square in plan view.

[0038] The resin molded object W has a bottom surface 15, a top surface 16, and side surfaces 17, which are machined surfaces. Preferably, the bottom surface 15, top surface 16, and side surfaces 17 are formed as smooth surfaces with virtually no irregularities macroscopically. However, considering that they will be used for machining, it is not necessary for all surfaces to be smooth, and the degree of smoothness only needs to be such that it does not hinder the machining process itself or the finished product after machining. For example, if the resin molded object W is a rectangular parallelepiped, at least the bottom surface 15, top surface 16, and each side surface 17 are formed in a planar shape. Also, for example, if the resin molded object W is a cylinder, a cylindrical shape, or a cone, the side surfaces 17 are formed in a cylindrical or spherical shape.

[0039] The resin molded object W is formed solidly at least in the height direction (thickness direction). That is, the resin material is densely connected from the bottom surface 15 to the top surface 16 of the resin molded object W. In this embodiment, the resin material is densely connected in the surface direction (XY axis direction) and the height direction (Z axis direction), making it solid, and basically no molding defects such as voids (porosity) occur within the thickness. Note that "solid" means that there are basically no voids within the thickness, and is not intended to exclude shapes that have gaps or voids in their external shape, such as cylindrical shapes or shapes with holes.

[0040] The rough molded object W1 for manufacturing the resin molded object W is molded to a size and shape that can enclose the desired resin molded object W. If the rough molded object W1 is molded to a size that is only slightly larger than the resin molded object W, the processing time required to remove the unnecessary parts of the rough molded object W1 and process it into the resin molded object W can be reduced, and the generation of unnecessary removal waste can be reduced. On the other hand, because the rough molded object W1 is formed more densely (solid) towards the center due to the thermal shrinkage of the resin material, the larger the removal allowance, that is, the larger the rough molded object W is molded to be, the higher the quality of the resin molded object W will be. Therefore, it is preferable to appropriately select the thickness of the removal allowance for the unnecessary parts of the rough molded object W1 according to the quality and cost of the resin molded object W.

[0041] Then, using 3D printer 1 (Figure 1), a rough shape W1 is fabricated by stacking layers LY of resin material R (fabrication process).

[0042] In this molding process, layer LY is formed, for example, by extruding resin material R from the nozzle 11 of the 3D printer 1 along a predetermined scanning path (scan line) L. The scanning path L can be set arbitrarily as long as it can fill layer LY without gaps with resin material R. For example, in the case of manufacturing a resin molded object W which is a rectangular parallelepiped with a square shape in plan view, as shown in Figure 3, the design is based on concentric ring-shaped 3D molding data in which a square SC that follows the outer shape of the rough molded object W1 in plan view is offset toward the center at a predetermined pitch p1. Note that "concentric ring" refers to a state in which multiple similar shapes that share a center are grouped together, and depending on the outer shape and shape of the resin molded object W, it may include oval shapes such as circles, ellipses, and ovals, as well as quadrilaterals, polygons, etc. Furthermore, although the case where the outer shape in plan view is a square SC is described, it is also possible to handle cases where the outer shape in plan view is a rectangle or parallelogram by arbitrarily scaling or tilting in the X-axis direction and / or Y-axis direction.

[0043] The pitch p1 can be set arbitrarily according to the type and grade of the resin material R, etc., as long as the adjacent rings of resin material R are connected, that is, if the resin material R extruded from the nozzle 11 overlap due to flow, weight, pressure, etc., but for example it should be less than or equal to the opening width of the nozzle 11 of the 3D printer 1. In this embodiment, the discharge port of the nozzle 11 is circular in shape, and the opening diameter (opening diameter of the nozzle 11) is 0.2 mm to 10.0 mm, preferably 0.2 mm to 2.0 mm. In this embodiment, for example, a 2.0 mm nozzle is used, and the pitch p1 is set to 1.6 mm, that is, the pitch p1 is less than the opening width of the nozzle 11 and greater than half the opening width of the nozzle 11. However, it is not limited to this, and any shape and size may be used depending on the dimensions of the rough molded object W1, the resin material R, and the amount of resin material R extruded from the nozzle 11. Even if the pitch p1 is larger than the opening width of the nozzle 11, it is possible to form a layer LY in which the resin material R, which has been compressed by flow, weight, and pressure after being discharged, is continuously connected without gaps, by increasing the discharge amount (discharge rate) of the resin material R from the nozzle 11. Furthermore, in cases such as when the nozzle 11 is small in diameter, it is possible to form a layer LY in which the resin material R is continuously connected without gaps, even if the pitch p1 is slightly smaller than half the opening width of the nozzle 11.

[0044] Next, in the molding process, offset lines OL, which serve as reference lines, are set at a pitch p1 between concentric rings, as shown in Figure 4, for the 3D molding data shown in Figure 3. These offset lines OL may be configured such that each offset line OL is a separate scanning path L, as shown in the example in Figure 5(a), and the central axis of the nozzle 11 or the discharge port of the nozzle 11 is moved to the adjacent scanning path L after completing one revolution, or multiple offset lines OL may be arbitrarily connected in a continuous stroke to form a single scanning path L, as shown in the example in Figure 5(b). It is preferable that the separate scanning paths shown in Figure 5(a) are each in a continuous stroke. In the example shown in Figure 5(b), multiple offset lines OL are connected to form a scanning path L such that when one revolution of an offset line OL is completed, the reader moves to the adjacent offset line OL, and then circles around that offset line OL in the opposite direction. Therefore, the nozzle 11 moving along the scanning path L will move from the starting point PS to the ending point PE in a short distance without basically self-crossing. Furthermore, at the starting point PS (ending point PE), the resin material R tends to accumulate, and this accumulation tends to result in larger unwanted parts being formed on the rough molded object W1. Therefore, it is preferable to set the starting point PS (ending point PE) at a position other than the vertices, for example, in the middle of the edges, to minimize the unwanted parts and reduce the removal process described later. Also, in Figure 5(b), the lines connecting the offset lines OL are shown slightly shifted to the left and right for clarity of explanation.

[0045] Then, by sequentially discharging the resin material R while moving the nozzle 11 along the scanning path L, that is, while circling the nozzle 11, as shown in Figures 6(a) to 6(c), adjacent resin materials R are formed in layers so as to fill the surface at a predetermined pitch p1, and adjacent molten resin materials R before solidification overlap in adjacent portions (shown by the dashed lines in the figures) to form a solid, planar layer LY with a predetermined cross-sectional shape. In layer LY, for portions that are not filled by the scanning path L, such as the central part of the figure drawn by the scanning path L, it is preferable to fill them so as not to create voids by, for example, increasing the amount of resin material R discharged from the nozzle 11 or arbitrarily moving the nozzle 11 separately from the scanning path L. In reality, the resin material R discharged from the nozzle 11 is stacked in a roughly semicircular cross-section depending on the influence of its viscosity and surface tension, but for the sake of clarity, it will be described as being stacked in a circular shape.

[0046] Then, in the fabrication process, as shown in Figure 7, the 3D printer 1 fabricates a rough object W1 by sequentially stacking layers LY with the same or similar cross-sectional shape at a predetermined stacking pitch p2, overlapping them in the height direction to form overlapping parts, so that the object becomes solid in the height direction. At this time, the scanning path of the nozzle 11 in each layer LY may be the same or different. For example, in the case of the scanning path L shown in Figure 5(a) or Figure 5(b), the endpoint PE of the lower layer is set as the starting point PS of the upper layer, and the starting point PS of the lower layer is set as the endpoint PE of the upper layer, so that the direction of movement of the nozzle 11 is opposite for the lower and upper layers, thereby allowing the nozzle 11 to move efficiently.

[0047] Regarding the layer pitch p2, it should be set so as to fill in the recesses caused by the layering marks on the upper part of the lower layer LY that are being layered, so that these recesses do not remain as voids inside the rough-formed object W1. Also, the smaller the layer pitch p2, and the closer the opening of the nozzle 11 is to the build table 5 or the lower layer LY, the more the resin material R is compressed and expanded, allowing for denser layering. In this embodiment, the layer pitch p2 may, in principle, be smaller than the opening width of the nozzle 11, for example, less than or equal to the pitch p1, or 0.8 mm as an example. In other words, the layer pitch p2 in this embodiment is greater than 0 and less than half the opening width of the nozzle 11. Therefore, the cross-sectional shapes (resin materials) of adjacent layers LY overlap (shown by the dashed lines in the figure), resulting in a solid shape in the height direction. Note that the layer pitch p2 does not need to be constant for all layers LY, and the layer pitch p2 may be arbitrarily changed according to the shape of the rough-formed object W1.

[0048] Examples of a rough-formed object W1 created by stacking multiple layers LY, for example, five layers, are shown in Figures 2(a), 8(a), and 8(b). In the rough-formed object W1, a layering mark S, which is an unwanted part caused by the cross-sectional shape of the resin material R extruded from the nozzle 11, is present on the top, and a layering mark S, which is an unwanted part caused by the stacking of the cross-sectional shapes of the resin material R, is present on the side.

[0049] Therefore, after removing the formed rough object W1 from the build table 5 of the 3D printer 1, the layer lines S on the surface of the rough object W1 are removed by a removal device to form the resin object W shown in Figure 2(b) (removal process). For example, when a cutting device is used as the removal device to remove the layer lines S, the rough object W1 is set in the cutting device, and the outer part (wall), which is the surface of the rough object W1, is cut using the cutting tool of this cutting device to form the cut surfaces, namely the bottom surface 15, top surface 16, and side surface 17, into a flat shape. Regarding the cutting tool, the finer the cutting area, the smoother the surface of the resin object W becomes, but there is a trade-off relationship between smoothness and processing time, so it should be selected according to the degree of smoothness required for the resin object W.

[0050] In the examples shown in Figures 2 to 8, the number of layers LY to be stacked was, for example, 5 layers. However, by increasing the number of layers LY, it is also possible to manufacture a cubic, rough-shaped object W1 (resin object W), as shown in the examples of manufacturing in Figures 9(a), 9(b), and 9(c). In the example of manufacturing shown in Figure 9(b), the processing time is shortened and waste is reduced because the removal process is simplified to remove the layer lines S. In the example of manufacturing shown in Figure 9(c), a smooth resin object W can be manufactured by performing the removal process more carefully.

[0051] In this way, by using a 3D printer 1 to build up layers of resin material R to create a solid, rough object W1, and then removing the layer lines S, which are unnecessary parts of the rough object 1, to create a resin object W, it is possible to manufacture resin objects W of any size using a variety of resin materials R that can be used with the 3D printer 1, without creating steps or other defects between layers. As a result, high-quality resin objects W of the desired size can be easily manufactured through a simple process.

[0052] When molding resin objects with a large height (thickness) by injection molding, internal defects such as voids and cavities inevitably occur due to internal heat generation, gas, and molding shrinkage. However, by using a 3D printer 1 to build a rough object W1 by stacking solid layers LY in the height direction to create a solid structure, it is possible to manufacture a rough object W1 (resin object W) with a large height (thickness) and fewer internal defects such as voids and cavities compared to when a rough object (resin object) is injection molded.

[0053] In the molding process, by extruding the resin material R while moving the nozzle 11 of the molding device in a continuous motion when molding each layer LY, the travel distance of the nozzle 11 can be shortened, and the molding speed of the rough molded object W1 is improved.

[0054] Furthermore, in the molding process, by sequentially layering the resin material R along the circumference of the rough molded object W1, uneven distribution of the resin material R in the manufactured rough molded object W1 is less likely to occur, improving the quality of the resin molded object W.

[0055] Furthermore, by overlapping the resin material R during the molding process and creating overlapping sections, gaps between the travel paths are eliminated for each layer LY, and in the height direction, the recesses of the layer lines formed for each layer LY are filled by the resin material R of the adjacent layer LY. This makes it less likely for voids to be contained within the rough molded object W1 (resin molded object W), allowing the rough molded object W1 to be molded solidly.

[0056] Furthermore, in the case of conventional resin blocks for machining produced by extrusion molding or injection molding, only resin materials suitable for each molding method can be used, and there are limitations on wall thickness, etc. In contrast, the resin molded object W of this embodiment can be formed by removing unnecessary parts from a rough molded object W1 using a 3D printer 1, and can be molded to any size and dimensions using any resin material without using a mold. In other words, it has a high degree of freedom in terms of material and dimensions, so it can be suitably used as a high-quality resin block for machining (cutting) consisting of the optimal dimensions (minimum required amount) including wall thickness and the optimal material regardless of grade. In short, since the resin molded object W can be molded in a dimensionally optimized state as a resin block for machining (cutting), it is suitable for manufacturing processed products of desired size, shape, and material, and the amount of material removed during machining can be minimized, resulting in a molded product with less material loss and environmental consideration. For example, by forming the resin molded object W as a rectangular prism, cube, or cylinder, it becomes a shape that is easy to machine. In particular, during the removal process, the rough molded object W1 can be machined to create flat surfaces on each side of the resin molded object W. Therefore, when machining (cutting) the completed resin molded object W, the flat surfaces can be used to firmly fix it with a holding jig, improving machining accuracy.

[0057] Therefore, using the method described above, it becomes possible to fabricate large resin molded objects W, such as water meter boxes, which previously required complex molds and have numerous ribs and other features.

[0058] Furthermore, since the resin molded object W can be formed as a single block, it is possible to reduce labor and costs compared to combining multiple plate-shaped or rod-shaped resin molded objects with adhesives or bolts to form a block, and it also contributes to environmental considerations. Moreover, since there are no joints such as those from adhesives in the resin molded object W, even when a processed product made from the resin molded object W is used in tests using fluids such as liquids, the safety factor related to the strength and watertightness performance of the resin molded object W can be calculated with high accuracy.

[0059] By using a fused deposition modeling (FDM) 3D printer 1, particularly a pellet-type 3D printer 1, it becomes possible to use a wide variety of inexpensive, readily available pellet-shaped thermoplastic resins (including recycled pellet materials) as the resin material R, and the resulting resin-formed object W can be suitably used as a resin block for machining, especially for cutting.

[0060] Since the resin-molded object W can be fabricated from any material, it is possible to combine multiple objects by bonding, ultrasonic welding, vibration welding, etc., to create a larger single resin-molded object (resin block), just like with conventional resin-molded objects.

[0061] In the above embodiment, the scanning path L of the nozzle 11 of the 3D printer 1 can be set arbitrarily as long as the layer LY can be filled with resin material.

[0062] For example, as shown in Figure 10(a), the scanning path L may be set in a zigzag pattern. In this example, the zigzag direction of the scanning path L is a polyline consisting of components parallel or substantially parallel to the X-axis and Y-axis directions. In this case, the same scanning path L may be used for each layer LY, but by making the endpoint PE of the scanning path L of one layer LY the starting point of the scanning path L of other layers LY stacked on that layer LY, the travel distance of the nozzle 11 can be suppressed and the printing speed of the rough-formed object W1 can be further improved. Furthermore, by making these scanning paths L intersect or orthogonal, for example, the interior of the rough-formed object W1 can be efficiently made solid. In that case, the finer the zigzag pattern, the more effectively the occurrence of porosity inside the rough-formed object W1 can be suppressed.

[0063] Furthermore, the zigzag direction of the scanning path L may be inclined with respect to the X-axis and Y-axis directions, as shown in the example in Figure 10(b).

[0064] Furthermore, as shown in Figure 10(c), the nozzle 11 may be moved along any scanning path, such as a random pattern, to fill the area excluding the outer part, and then the scanning path L may be set to create the outer part surrounding those areas along the circumference. Alternatively, the order may be reversed, so that the outer part surrounding the outer area is created first, and then the inside is filled with any scanning path L, such as a random pattern.

[0065] In Figures 10(a) to 10(c), examples of scanning paths for other stacked layers LY are shown with dashed lines.

[0066] Furthermore, in order to further reduce the amount of material removed during the removal process, i.e., the layer lines S, the movement of the nozzle 11 during the molding process may be made seamless, making it less likely for it to stop at corners or vertices, and a scanning path L may be set that creates corners at the vertices of the rough molded object W1. In other words, the movement of the nozzle 11 is made smoother, reducing the accumulation of resin material R caused by the stagnation of the nozzle 11 (resin accumulation), and the outer shape of the rough molded object W1 is made closer to the outer shape of the resin molded object W, resulting in a molded object with fewer unnecessary parts.

[0067] For example, as shown in Figure 11(a), the scanning path L is set as a polyline consisting of straight lines along the X-axis and Y-axis directions, winding in a lightning-bolt (angular spiral) pattern. The pitch of the lines in the scanning path L may be greater than or less than the diameter of the nozzle 11, but the gap should be small enough to be filled by the adhesion of the resin material R discharged from the nozzle 11. The scanning direction of the scanning path L may be from outside to inside or from inside to outside. In the illustrated example, for example, the upper right endpoint in the figure is set as the starting point PS, and the scanning path L is set to gradually wind inward in a clockwise direction. This scanning path L is a polyline with equally spaced or approximately equally spaced lines.

[0068] Preferably, the scanning path L is set to be a closed curve when viewed from the stacking direction, as shown in Figure 11(b), based on the example shown in Figure 11(a). That is, the scanning path L is configured such that the starting point PS and the ending point PE coincide when viewed from the stacking direction. In this case, the scanning path L has a shape in which the endpoints of a double shape consisting of lightning-shaped offset lines offset on both sides of the lightning pattern shown in Figure 11(a) are connected. Therefore, this scanning path L is a single-stroke drawing in which the starting point PS and the ending point PE coincide when viewed from the stacking direction.

[0069] More preferably, in the example shown in Figure 11(b), the scanning path L is made in a single continuous stroke, including the stacking direction, and in this embodiment, the Z-axis direction as well. That is, the scanning path L is spiral in shape, extending in the stacking direction. Therefore, the 3D printer 1 extrudes the resin material R while continuously moving the nozzle 11 in the stacking direction at a predetermined speed to stack the material. The speed at which the nozzle 11 moves in the stacking direction is set according to, for example, the type of resin material R and the size of the resin molded object W. This speed is basically constant, but it may vary in some parts. Then, along the scanning path L shown in Figure 11(b), in the molding process, the 3D printer 1 stacks the resin material R while moving in the X-axis, Y-axis, and Z-axis directions to create a rough molded object W1 that is solid. An example of the molding of a rough molded object W1 based on the scanning path L shown in Figure 11(b) is shown in Figure 12(a), and an example of the molding of a resin molded object W produced after a removal process is shown for the rough molded object W. Figure 12 shows an example where a pellet-type 3D printer 1 is used, and a colored thermoplastic resin (e.g., ABS) is used as the resin raw material R.

[0070] In this way, by forming the scanning path L in a lightning bolt pattern, corners are created at the vertices of the rough-formed object W1. This not only suppresses the amount of material removed during the removal process, but also reduces the amount of material removed. Furthermore, because the nozzle 11 moves in a straight line over a short distance, the timing of extruding the resin material R at one line in the scanning path L is close to the timing of extruding the resin material R at the adjacent line. As a result, adjacent resin material R pieces adhere to each other while melted, making it easier for the resin material R pieces to weld together even at a low extrusion rate. Moreover, when the extrusion rate is increased, defects such as voids and cavities inside are less likely to occur, resulting in a good finish for both the rough-formed object W1 and the resin-formed object W.

[0071] Compared to the example shown in Figure 5(b), the lightning-shaped scanning path L has fewer bends in the same area, thus simplifying and shortening the movement path of the nozzle 11, resulting in a better finish for the rough molded object W1 and the resin molded object W.

[0072] Furthermore, by continuously moving the nozzle 11 in the layering direction while extruding and layering the resin material R, the nozzle 11 is constantly moving, making it difficult for areas where the resin material R accumulates to form. This suppresses irregularities on the sides of the rough molded object W1, i.e., layer lines S, and also reduces the extrusion rate, enabling the creation of a rough molded object W1 with less resin material R. Combined with the reduction in cutting volume due to the lightning-shaped form, this reduces material loss, making it possible to manufacture environmentally friendly and low-cost resin molded objects W. It is also possible to reduce the screw rotation speed to lower the extrusion volume and thus the extrusion rate. For example, in the case shown in Figure 12 above, it was found that even when the screw rotation speed was reduced and the extrusion rate was reduced to 95%, the layered resin materials R adhered closely to each other, and defects such as voids and cavities did not occur.

[0073] As another example, the scanning path L may be a space-filling curve (Peano curve) on any 2D plane with a finite depth, such as a Hilbert curve with a finite depth that fills the square SC almost evenly. Figure 13 shows an example of a scanning path L using a Peano curve. In this example, the scanning path L is a closed curve formed by connecting the endpoints of a double-shaped polyline, which consists of a linearly symmetrical Peano curve, i.e., an S-shaped polyline and an inverted S-shaped polyline, which are connected symmetrically or nearly symmetrically, with offset lines on both sides of the polyline. Therefore, when viewed from the stacking direction or in a plan view, this scanning path L is a single-stroke drawing in which the starting point PS and ending point PE coincide. In this case, the starting point PS (ending point PE) can be any position, but since the resin material R tends to accumulate at the starting point PS (ending point PE), in order to reduce the layer lines S on the outer part of the rough molded object W1, it is preferable to set it at the outermost position in the scanning path L, that is, at a position away from the center (inward) from the position that forms the outer part of the rough molded object W1. The pitch of the lines in the scanning path L may be greater than or less than the diameter of the nozzle 11, but the gap should be such that it is filled by the adhesion of the resin material R discharged from the nozzle 11.

[0074] More preferably, in the example shown in Figure 13, similar to the example shown in Figure 11(b), the scanning path L is made in a single stroke, including the stacking direction, and in this embodiment, the Z-axis direction. Then, along the scanning path L shown in Figure 13, in the manufacturing process, the 3D printer 1 stacks the resin material R while moving in the X-axis, Y-axis, and Z-axis directions to create a rough object W1 that is solid in the surface direction (plan view) and height direction. An example of the creation of a rough object W1 based on the scanning path L shown in Figure 13 is shown in Figure 14. In Figure 14, for example, a pellet-type 3D printer 1 is used, and a colored thermoplastic resin (e.g., ABS) is used as the resin material R.

[0075] In this way, by forming the scanning path L into a simple bent shape using Peano curves, a corner is formed at the vertex of the rough-formed object W1, and the resin-formed object W can be easily manufactured simply by removing the frill-shaped layer lines S that basically protrude from both the left and right sides (X-axis and Y-axis directions) in the removal process. In particular, in the example of the scanning path L shown in Figure 13, the folded portion is set close to the outside of the rough-formed object W1, so that the frill-shaped layer lines S caused by the accumulation of resin material R due to the folding of the nozzle 11 can be set on the outside of the rough-formed object W1, and compared to the case where the folded portion is set on the inside of the rough-formed object W1, voids etc. caused by resin accumulation are less likely to occur inside the rough-formed object W1. Furthermore, for example, by taking into account the cutting dimensions of the frill-shaped layer lines S in advance, it is also possible to easily manufacture a prismatic rough-formed object W1 with a square base simply by cutting the two sides that have the frill-shaped layer lines S. In other words, the removal process required to produce a high-quality resin molded object W is simple and quick, reducing manufacturing effort and costs. Furthermore, the travel distance of the nozzle 11 is the shortest distance to fill the square SC, and the length of the straight lines in the left-right direction in the scanning path L is approximately constant, which reduces the likelihood of uneven distribution of the resin material R. Additionally, the timing of extrusion of the resin material R between adjacent lines is close, making it easier for the resin material R to adhere to each other while molten. This allows the resin material R to weld together even at a low extrusion rate, reducing the likelihood of defects such as porosity and voids, resulting in a better finish for both the rough molded object W1 and the resin molded object W.

[0076] The scanning path L shown in Figure 13, formed based on the Peano curve, is more efficient than the examples shown in Figure 5(b) and Figure 11(b) for the same area, as it has fewer bends. This simplifies and shortens the movement path of the nozzle 11, resulting in a better finish for the rough molded object W1 and the resin molded object W, making it the most versatile scanning path L. Furthermore, in the removal process, by setting the removal direction of the layer lines S by the removal device, for example, the cutting direction by the cutting device, to the direction in which the scanning path L extends, i.e., the left-right direction (XY axis direction) in Figure 13, the direction of the layer lines S by the scanning path L and the direction of the cutting marks approximately coincide, making the layer lines S less noticeable when the resin molded object W is manufactured.

[0077] Furthermore, by continuously moving the nozzle 11 in the layering direction while extruding the resin material R and layering it, the nozzle 11 is constantly moving, making it difficult for areas where the resin material R accumulates to form. This suppresses irregularities on the sides of the rough molded object W1, i.e., layer lines S, and also reduces the extrusion rate, enabling the creation of a rough molded object W1 with less resin material R. Combined with the reduction in cutting amount due to the lightning-shaped form, this allows for production with less resin, reducing material loss and enabling the production of environmentally friendly and low-cost resin molded objects W. In the example shown in Figure 14 above, it was found that if the extrusion rate is at least 92.5%, the resin material R adheres well and defects such as porosity and voids do not occur.

[0078] Furthermore, if the resin molded object W is of a size and shape that fits within the portion of the rough molded object W1 excluding the unnecessary parts, it is possible to manufacture a resin molded object W, such as a cylindrical or conical shape, by removing the unnecessary parts from a rectangular or cubic rough resin molded object W through a removal process as described above. However, the outer shape of the rough molded object W1 itself may also be cylindrical or cylindrical.

[0079] For example, as shown in Figure 15(a), a scanning path L may be set by connecting concentric ring-shaped lines in a single stroke, or as shown in Figure 15(b), a scanning path L may be set in the shape of an Archimedean spiral, that is, in the shape of an equally spaced spiral curve. In the example shown in Figure 15(b), for example, the scanning path L of each layer LY may be set in the shape of a two-dimensional Archimedean spiral, and in one layer LY, the resin material R is discharged while the nozzle 11 moves in a spiral shape from the outer end or the center to the center or the outer end, and the endpoint of that scanning path L is set as the starting point of the scanning path L of the other layer LY that is laminated on that layer LY, and the nozzle 11 is moved in reverse to follow the same scanning path L as the first layer LY, thereby suppressing the distance the nozzle 11 moves between layers LY. Furthermore, for example, if you want to create a cone-shaped resin object W, in the example shown in Figure 15(b), the scanning path may be made into a three-dimensional Archimedean spiral, and the resin material may be extruded and layered while the nozzle 11 is continuously moved in the layering direction. Since the example of the scanning path L shown in Figure 15(b) is curved, the travel distance is relatively longer compared to the examples of scanning path L shown in Figure 5(b) and Figure 11(b), but because the printing time for each layer LY is longer, the temperature of the rough object W1 after the completion of the molding is lower, making it less likely for warping to occur. Also, when layering in the Z direction, the temperature of the parts that have been layered and completed earlier is lower, making it less likely for layering defects (e.g., layer collapse) due to excessive heat to occur. Therefore, when manufacturing a large resin object W, using a rough object W1 manufactured based on the scanning path L shown in Figure 15(b) can result in a resin object W of better quality.

[0080] Therefore, when it is desirable to manufacture with a small amount of resin and reduce porosity in the molded object W, a rough molded object W1 can be manufactured using the scanning path L shown in Figure 13, and when it is desirable to prevent warping of the resin molded object W, a rough molded object W1 can be manufactured using the scanning path L shown in Figure 15. By cutting away the unnecessary parts in each case, it is possible to create a resin molded object W that matches the desired quality and shape.

[0081] Furthermore, in the case of the Archimedean spiral, the equations are expressed as Xt=a·t·cost, Yt=b·t·sint, and Zt=t, using coefficients a, b, and the parameter t. Because the equations are simple, rough-shaped objects W1 such as ellipsoids can be easily manufactured by setting coefficients a and b to different numbers for Xt, Yt, and Zt. By using a three-dimensional Archimedean spiral scanning path, it is possible to reduce the amount of unwanted material that needs to be removed, especially when obtaining a resin-molded object W from a rough-shaped object W1 in the shape of a cone.

[0082] Furthermore, when manufacturing a resin molded object W having a cylindrical or other circular base shape, by setting a square-shaped scanning path L with this circle as the inscribed circle and molding a rough molded object W1, the amount of unnecessary material to be removed when obtaining the resin molded object W can be further reduced.

[0083] Furthermore, by forming the scanning path L shown in Figures 5(b), 15(a), and 15(b) in a closed curve shape, it becomes possible to continuously move the nozzle 11 in the stacking direction while discharging and stacking the resin material R.

[0084] Furthermore, when the scanning path L is a closed curve, for example, by setting the lines close together, these multiple lines can be used to manufacture walls and other parts of the rough-formed object W1, i.e., resin-formed object W, that are wider than the diameter of the nozzle 11, i.e., have a greater thickness. This eliminates the need to repeatedly replace the nozzle 11, and allows for the manufacture of resin-formed objects W with a thickness independent of the diameter of the nozzle 11, simply by setting the scanning path L. Figure 16 shows an example of a scanning path L for forming a cylindrical, for example, hexagonal cylindrical, rough-formed object W1. In this example, by setting the scanning path L as a closed curve and making the portion corresponding to the outer part of the rough-formed object W1 multiple, the thickness of the outer part can be made approximately twice the diameter of the nozzle 11, in this embodiment approximately twice the diameter. Furthermore, in the case of a scanning path L for forming a cylindrical rough-shaped object W1, if it is formed in the shape of a closed curve, connection points inevitably occur at the points where multiple lines connect. If these connection points are exposed to the surface, even if the layer lines S are removed, traces of the connection points will remain on the surface. Therefore, a protruding portion 18 is set to cover the connection points from the outside when manufacturing the rough-shaped object W1. For example, by setting a starting point PS (ending point PE) on the protruding portion 18, the outer part of the protruding portion 18 is removed as an unnecessary part by cutting or other means from the position shown by the dashed line IL in the figure during the removal process. This prevents the connection points from being directly exposed to the surface, thus maintaining a good appearance. An example of a resin-molded object W formed based on the scanning path L shown in Figure 16 is shown in Figure 17. This resin-molded object W is, for example, a lampshade, and by gradually changing the circumferential angle of the scanning path L in the layering direction, it has a circumferentially twisted shape. In this way, even if the scanning path L of each layer has the same pattern, a rough-shaped object W1 (resin-molded object W) with a complex shape can be manufactured by changing the angle in the circumferential direction in the layering direction. Lamination marks appearing on the outer surface can be removed by polishing and / or cutting as needed during the removal process.

[0085] Furthermore, the scan path patterns of each layer do not have to be the same or similar; for example, the scan path patterns described above may be different for each layer and combined arbitrarily.

[0086] Furthermore, the 3D printing equipment is not limited to single-nozzle head specifications; it may also be a dual-nozzle head specification (multi-nozzle head specification). In particular, in the case of a specification with multiple nozzles that can move independently in the X-axis and Y-axis directions, it becomes possible to print more multi-functional resin objects W by, for example, using different resin raw materials for each nozzle to make up the rough-formed object W1 (resin-formed object W). For example, it becomes possible to reduce manufacturing costs by using resin raw materials with high material costs only in the necessary parts and using resin raw materials with low material costs for the remaining parts. As an example, by making the outer part (surface part) of the rough-formed object W1 (resin-formed object W) with a resin raw material such as ASA which has good weather resistance, and the inner part with a resin raw material such as ABS which is cheaper, it is possible to manufacture a resin-formed object W with excellent weather resistance at low cost without applying a coating after the resin-formed object W is manufactured. Also, even with the same resin raw material, it is possible to print resin-formed objects W with different colors and physical properties in parts by using different colors and grades for each nozzle. Furthermore, it is possible to create resin molded objects W by combining incompatible resin raw materials.

[0087] In 3D printing, it is possible to manufacture a resin object W with a thickness independent of the diameter of the nozzle 11 by setting the scanning path L in a single stroke, without using commonly used methods such as layering raster (infill) and contour (wall) layers, or increasing the extrusion volume. Note that the layering method is not limited to this; any method in which the resins melt and adhere to each other is acceptable.

[0088] Furthermore, the molding apparatus is not limited to a configuration in which the molding head (discharge means) having a nozzle for discharging resin material is movable in the X-axis and Z-axis directions and the molding table is movable in the Y-axis direction. It is sufficient if the molding head is movable in at least three dimensions relative to the molding table. For example, the molding head may be movable in the X-axis and Y-axis directions and the molding table may be movable in the Z-axis direction, or the molding head may be provided at the tip of a robot arm (preferably a robot arm of a 6-axis robot) and be movable in any direction including the three directions of the X-axis, Y-axis, and Z-axis.

[0089] For example, the build table 5 may also be configured to be movable / rotatable along the X, Y, and Z axes. In these configurations of the build table 5, at least one of the three axes must be selected.

[0090] Furthermore, in the case of fractal figures (such as Hilbert curves) that fill a three-dimensional space with a single stroke, especially in 8-axis or 9-axis printing, the printing efficiency is improved because the nozzles can be smoothly printed without interference and can move relatively along the shortest distance. [Explanation of symbols]

[0091] 1. 3D printer, a device for manufacturing shaped objects. 11 nozzles 15. The top surface, which is the cutting surface. 16. The bottom surface, which is the cutting surface. 17. Side surface which is the cutting surface LY layer R Resin material S is the unnecessary part, the layering trace. W Resin molded object W1 Roughly shaped object

Claims

1. A method for manufacturing resin molded objects, which involves manufacturing three-dimensional resin molded objects. A molding process in which a resin material is layered using a molding machine to create a rough shape, A removal step is performed to remove unnecessary parts of the rough molded object and create a resin molded object, A method for manufacturing resin molded objects, characterized by comprising the following features.

2. The object manufacturing device is a fused deposition modeling (FDM) 3D printer. A method for manufacturing a resin molded object according to claim 1, characterized by its features.

3. The resin material is a pelletized thermoplastic resin. A method for manufacturing a resin molded object according to claim 1, characterized by its features.

4. In the molding process, the nozzle of the molding machine is moved along a space-filling curve on an arbitrary two-dimensional plane with a finite depth while extruding resin material. A method for manufacturing a resin molded object according to claim 1, characterized by its features.

5. In the molding process, the nozzle of the molding machine is moved in a closed curve while extruding the resin material. A method for manufacturing a resin molded object according to claim 1, characterized by its features.

6. In the molding process, the nozzle of the molding machine is moved in a continuous, straight line while extruding the resin material. A method for manufacturing a resin molded object according to claim 1, characterized by its features.

7. In the molding process, the resin material is overlapped to create overlapping areas. A method for manufacturing a resin molded object according to claim 1, characterized by its features.

8. In the molding process, the nozzle of the molding machine is continuously moved in the layering direction while extruding the resin material. A method for manufacturing a resin molded object according to claim 1, characterized by its features.

9. In the molding process, resin material is layered sequentially along the circumference of the rough molded object. A method for manufacturing a resin molded object according to claim 1, characterized by its features.

10. In the removal process, the surface of the roughened object is cut to create a machined surface. A method for manufacturing a resin molded object according to claim 1, characterized by its features.

11. Unnecessary parts are layering marks. A method for manufacturing a resin molded object according to claim 1, characterized by its features.

12. Resin molded objects are resin blocks for machining. A method for manufacturing a resin molded object according to claim 1, characterized by its features.

13. Resin molded objects are resin blocks for machining. The method for manufacturing a resin molded object according to claim 10, characterized in that it is a method for manufacturing a resin molded object.

14. Resin molded objects are one of the following shapes: rectangular prism, cube, cylinder, sphere, pyramid, or cone. A method for manufacturing a resin molded object according to claim 1, characterized by its features.

15. The resin-molded object is cylindrical. A method for manufacturing a resin molded object according to claim 1, characterized by its features.

Images