Injection molding die and molding method using the same

Abstract

To make it possible to manufacture high-quality molded product that satisfy product function and dimension, by preforming an injection molding die into a product shape taking into account deformation of a resin.SOLUTION: In a molded product molded by a concave die 10 having a groove 11, a portion of the groove (groove 41) is formed on a movable piece 30 arranged in an accommodation space within the concave die 10. The molded product is formed by injecting a resin into the first groove 11 and the second groove 41. An arc-shaped sliding surface 35 is formed on the movable piece 30, and the movable piece 30 can move slightly along an arc-shaped guide surface 25 in a direction of arrow 9b or the opposite direction, making it possible to slightly adjust an angle of the groove 41 relative to the groove 11.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a mold injection die that enables preforming of a product shape in response to product deformation due to differences in resin shrinkage after injection molding, and a molding method using the die. [Background technology]

[0002] In molding resin using an injection mold, high-temperature molten resin is poured into the mold and cooled to solidify. Patent Document 1 discloses a method of forming a molded product between two molding dies. When removing the molded resin, the product may be slightly deformed due to the shrinkage of the resin after molding and cooling. To deal with this, it is common to design injection molds while taking into account the shrinkage of the resin. However, when molding different resin materials using the same mold, the degree of deformation differs depending on the resin material, and the product may not satisfy the product's function after molding or may be outside the dimensional tolerance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 55-46717 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, in the injection molding of resin using a mold, the product may be deformed due to differences in resin shrinkage, etc., which may affect the product's functions and dimensions.

[0005] An object of the present invention is to enable the production of high-quality molded products that satisfy product functions and dimensions by preforming an injection molding die into a product shape that takes into account deformation of the resin. Another object of the present invention is to realize an injection molding tool and a molding method using the same that can easily accommodate a variety of materials that have different degrees of resin shrinkage after molding, by using a piece that is arranged so that it can move slightly in the injection molding die used. [Means for solving the problem]

[0006] Representative features of the invention disclosed in this application are as follows. According to one feature of the present invention, a mold for manufacturing a molded product by injection molding has a concave mold and a convex mold arranged to sandwich the resin supplied from a resin injection port, and a first groove for forming the molded product is formed in the concave mold, and a movable piece is arranged that is rotatable relative to the concave mold within a predetermined range around the rotation center point and has a second groove formed to connect to the first groove. The rotational position of the movable piece relative to the concave mold is fixed by a fixing means such as a bolt so that the movable piece does not move during injection molding. During injection molding using a mold, the rotational position of the movable piece is adjusted and fixed to the concave mold so that the molded product is bent in the opposite direction to the direction of bending after molding, i.e., in a preform shape, in anticipation of the degree of deformation of the molded product after molding, and a movable piece whose angle can be changed is used to bend a part of the mold groove in advance in the opposite direction to the deformation direction, thereby making it possible to adjust the shape of the mold according to the degree of deformation of the resin material used, and easily blow molding in a preform shape.

[0007] According to another feature of the present invention, a storage section that serves as a space for storing the movable piece is formed on the side of the concave die facing the convex die. The movable piece is formed with an arc-shaped sliding surface that guides rotation along the rotation center point, and an arc-shaped guide surface is formed on the inner wall of the convex die that corresponds to this sliding surface. When the movable piece rotates, the fixed position of the movable piece is adjusted by rotating the movable piece so that the sliding surface slides against the guide surface. In addition, the first groove portion is formed to intersect with the guide surface, and the second groove portion is formed to intersect with the sliding surface, and the positional relationship is such that the end of the first groove portion and the second groove portion are continuous regardless of the rotation position of the movable piece.

[0008] According to yet another feature of the present invention, a through hole is formed from the outside of the concave mold to the housing portion, a bolt is attached from the outside through the through hole, and a female thread portion is formed in the movable piece to screw with the male thread of the bolt. The female thread portion formed in the movable piece is formed radially outward from the rotation center point and farther from the sliding surface, at a position that does not interfere with the second groove portion. In addition, the molded product includes a bent portion, and the sliding surface and the guide surface are arranged to intersect with the extension direction at the bent portion.

[0009] According to yet another feature of the present invention, there is provided a method for molding resin using a mold having a concave mold and a convex mold arranged to sandwich the resin supplied from a resin injection port, and for producing a molded product by blow molding, in which a movable piece with a nested structure whose fixed position can be moved by a small rotation angle is arranged in the concave mold, and the position of the movable piece is adjusted so as to shift in the opposite direction to the deformation direction by an amount that takes into account deformation of the product after molding with resin, thereby setting a groove portion in the mold having a shape slightly different from the dimensions of the molded product, and after fixing the position of the movable piece, the convex mold is aligned with the concave mold and blow molding is performed. Effect of the Invention

[0010] As described above, according to the present invention, the relationship between the groove formed in the concave mold and the position of the groove by the movable piece can be preformed to a product shape that takes into account deformation due to differences in resin shrinkage, etc., and then the resin can be molded, so that it is easy to make the resin have an ideal shape when it shrinks after molding, making it possible to provide a high-quality molded product that satisfies product functions and dimensions. Also, even if there are multiple resin materials used in molding, there is no need to prepare multiple concave molds adjusted to the types of resin, which reduces manufacturing costs. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view showing an example of a molded product 1 produced using a mold. [Diagram 2]FIG. 1 is a top view showing a mold 10 and a piece 30 according to an embodiment of the present invention (state 1). [Diagram 3] FIG. 2 is a top view showing the mold 10 and the piece 30 according to the embodiment of the present invention (state 2). [Figure 4] FIG. 2 is a perspective view of a mold 10 and a piece 30 according to an embodiment of the present invention. [Diagram 5] 2 is a perspective view of the mold 10 and the piece 30 according to the embodiment of the present invention, seen from a different angle. FIG. [Figure 6] 1 is a perspective view of a protruding die 60 as seen from the back side. [Figure 7] FIG. 1 is a top view of a mold 10 according to an embodiment of the present invention. [Figure 8] 1A to 1C are four-sided views of a mold 10 according to an embodiment of the present invention. [Figure 9] FIG. 2 is a top view of a bridge 30 according to an embodiment of the present invention. [Figure 10] 2A to 2C are four-sided views of a block 30 according to an embodiment of the present invention. [Figure 11] FIG. 1 is a perspective view of a conventional mold 110. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLES

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following drawings, the same parts are given the same reference numerals, and repeated explanations will be omitted. In this specification, the width direction (+X), height direction (+Y), thickness direction (+Z), and rotation center point will be described as directions and positions shown in the drawings. In the following specification, the term "mold" in the broad sense refers to a set of a concave side mold 10 having a piece 30 and a convex side mold 60, but the concave side mold 10 having the piece 30 may also be simply called a "mold".

[0013] FIG. 1 is a perspective view showing an example of a molded product 1 manufactured using a mold according to this embodiment. The molded product 1 is a J-shaped molded member made of synthetic resin, and forms, for example, a part of a hook member. The cross-sectional shape of the molded product 1 is a rectangle with a width W, a depth D, and a height H, and the molded product 1 is an integral product with a constant depth D at any position in the XY direction. The molded product 1 is composed of two columnar parts 2 and 6 that are straight in the Y direction, a columnar part 4 that is straight in the X direction, a bent part 3 that connects the columnar parts 2 and 4, and a bent part 5 that connects the columnar parts 4 and 6. The ranges of these parts 2 to 6 are indicated by the ranges of the double-pointing arrows in the figure.

[0014] Before describing the details of the mold of this embodiment, a conventional mold 110 will be described with reference to FIG. 11. Conventionally, the molded product 1 shown in FIG. 1 is manufactured by using a concave mold (cavity) 110 having a groove 111 corresponding to the product shape of the molded product 1. A resin injection port (not shown) called a gate is formed in part of the groove 111 for injecting resin from the outside, and a through hole called an air vent (not shown) is provided for discharging compressed air in the groove 111 to the outside of the mold when the resin is poured, but is not shown in FIG. 11. After closing this mold 110 with a flat convex mold (core), liquid resin is injected from the resin injection port to fill the groove 111 with resin, and the resin is then cured. The convex mold to be combined with the concave mold 110 has the same shape as the convex mold 60 described later in FIG. 6.

[0015] Return to FIG. 1. When molding resin using the mold 110 shown in FIG. 11, the molded product 1 may be slightly deformed due to the difference in shrinkage of the resin when the molten resin is poured into the groove 111 and solidifies, and the desired product shape may not be formed. That is, in the case of the shape of the molded product 1 shown in FIG. 1, the columnar portion 6 may fall in the direction of the arrow 7, and the open end 6a side of the columnar portion 6 may be inclined inward (in the direction in which the columnar portion 6 approaches the parallel columnar portion 2). One of the reasons for this is that the hardening of the bent portion 5 is not uniform on the inner and outer periphery sides. There may be other reasons why the molded product is easily deformed in the direction of the arrow 7, but the explanation of the reason for the deformation will be omitted here. FIG. 2 shows the mold according to this embodiment, which has been improved to address this issue.

[0016] FIG. 2 is a top view of a concave mold 10 according to an embodiment of the present invention and a movable piece 30 disposed in a storage section 20 provided in the mold 10. In this embodiment, the mold for the molded product 1 shown in FIG. 1 is not constructed of a single mold, but is constructed of a groove 11 formed in the mold 10 and a groove 41 formed on the piece 30 side that is continuous with the groove 11. The final shape of the molded product 1 manufactured using the mold 10 and the piece 30 is the same as that shown in FIG. 1 (however, in a state where the mold is not tilted in the direction of the arrow 7 in FIG. 1). In this embodiment, the part that is likely to shrink when the resin hardens is preformed into a shape slightly different from the product shape using a piece (movable piece) 30 that is a separate member from the mold 10 and can be moved slightly relative to the mold 10, and then blow molding is performed with the resin.

[0017] The mold 10 is formed with a first groove 11 for pouring resin. The first groove 11 is a groove with a rectangular cross section for forming the entire columnar portion 2, the bent portion 3, and the columnar portion 4 of the molded product 1 shown in FIG. 1, and half of the bent portion 5, and includes a straight portion 12, a curved portion 13, a straight portion 14, and a curved portion 15. The movable piece 30 arranged in the storage section 20 is formed with a second groove 41 continuing from the first groove 11. The movable piece 30 is made of metal and is a separate member from the mold 10. In order to form the columnar portion 6 and the bent portion 5 of the molded product 1 shown in FIG. 1, a groove 41 consisting of a straight portion 45 and a curved portion 46 is formed. The concave mold 10, the movable piece 30, and the convex mold 60 can be manufactured from the same metal material.

[0018] The housing section 20 is formed so that the piece 30 can rotate therein by a small angle (e.g., less than a few degrees). That is, the housing section 20 is formed so that the space is slightly larger than the outer shape of the piece 30. Fig. 2 shows the piece 30 fixed at a counterclockwise rotation position when viewed from above. The piece 30 can move in the direction of the arrow 9a or in the opposite direction 9b (see Fig. 3) around the rotation center point 8 as an axis.

[0019] The accommodation section 20 is formed with a planar first long side portion 21 extending in the Y and Z directions on the side closer to the straight line portion 12, and a second long side portion 23 substantially parallel to the first long side portion 21 so as to face the first long side portion 21. The first long side portion 21 and the second long side portion 23 are connected at the sides farther from the rotation center point 8 by the outer short side portion 22, and at the sides closer to the rotation center point 8 are connected to the inner short side portion 24 and a guide surface 25. The piece 30 is formed with a first side surface 31 facing the first long side portion 21, a second side surface 33 facing the second long side portion 23, an outer end arc surface 32 connecting the first side surface 31 and the side farther from the rotation center point 8 of the second long side portion 23, and an inner peripheral surface 34 and a sliding surface 35 connecting the first side surface 31 and the side closer to the rotation center point 8 of the second long side portion 23. In the state shown in FIG. 2, the first long side 21 of the piece 30 and the first side surface 31 of the storage section 20 are in close contact with each other, and the second long side 23 and the second side surface 33 of the storage section 20 are spaced apart from each other.

[0020] 3 is a top view showing the die 10 and the piece 30 according to this embodiment, and shows a state in which the piece 30 has been rotated clockwise from the fixed angle shown in FIG. 2 by the maximum angle in the direction of the arrow 9b. In this state, the second long side 23 of the housing 20 is in good surface contact with the second side surface 33 of the piece 30. Meanwhile, the first long side 21 of the housing 20 has a gap with a distance from the first side surface 31 of the piece 30. A large gap is formed between the one side corner 22a of the first long side 21 of the housing 20 and the opposing corner of the piece 30 (the connection point between the first side surface 31 and the tip arc surface 32). This is merely a space for the piece 30 to enter, i.e., a shape that is useful when cutting the housing 20, and a gap is not necessarily required.

[0021] In order to enable the movable piece 30 to rotate and to assist the piece 30 in rotating smoothly without deviation from its axis with respect to the rotation center point 8, the piece 30 is formed with a sliding surface 35 having an arc-shaped shape when viewed from above. In addition, a guide surface 25 having an arc-shaped shape is formed at a portion of the die 10 corresponding to the sliding surface 35. When the piece 30 rotates slightly, the sliding surface 35 slides against the guide surface 25, thereby adjusting the rotation angle of the piece 30. In FIG. 3, the contact portion between the sliding surface 35 and the guide surface 25 is highlighted with a thick black line. The sliding surface 35 and the guide surface 25 are slightly less than ¼ of a circle when viewed from above, and the radius from the rotation center point 8 is r. The size of r is arbitrary, but it is preferable to set it within the range from the radius of curvature r1 on the inner circumference side of the bent portion 5 (see FIG. 1) to the radius of curvature r2 on the outer circumference side, and here, it is set to a size of about r=(r1+r2) / 2.

[0022] The manufacturing method for performing blow molding using the above-described concave mold 10 is as follows. (1) Insert the piece 30 into the accommodation portion 20 of the fixed concave mold 10, and set the position of the groove 41 relative to the groove 11 so that the preformed molded product is bent in the reverse direction by an amount corresponding to the amount of return based on experimental data values ​​for the amount of return of the injected resin after solidification. Specifically, adjust the rotational position of the piece 30, and fix the piece 30 to the concave mold 10 at the adjusted position with a bolt (not shown). Then, place the convex mold 60 (see FIG. 6 described later), which serves as the core of the movable side, over the concave mold 10. At this time, not only the groove 11 of the concave mold 10 but also the groove 41 of the piece 30 are covered by the convex mold 60. (2) Heated and liquefied resin material is injected into the cavity formed by the grooves 11, 41 formed by the concave mold 10 and the piece 30. This injection method can be the same as that of a known blow molding method. The concave mold 10 is provided with a resin injection port (gate) (not shown). In addition, a hole (air vent) (not shown) is further provided to exhaust air compressed inside the mold when resin is poured into the concave mold 10. (3) After injection, open the concave mold 10 and the convex mold 60. The molded product often sticks to one side. (4) Pull the molded part away from the side of the mold where it is stuck.

[0023] As described above, in this embodiment, the concave side mold 10 is not divided into two or more parts and assembled, but rather the concave side mold 10 has a nested structure with the movable piece 30 provided on the inside, making it possible to apply preform correction to the mold to accommodate the amount of deformation of the resin after molding.

[0024] FIG. 4 is a perspective view of the concave die 10 and the piece 30 according to the embodiment of the present invention. FIG. 4(A) is a perspective view of the concave die 10 with the piece 30 removed, and FIG. 4(B) is a perspective view of the piece 30 alone. The concave die 10 has a groove 11 formed therein that corresponds to the shape of the molded product 1. The cross-sectional shape of the groove 11 perpendicular to the longitudinal direction (extension direction) is rectangular, and straight line parts 12 and 14 corresponding to the columnar parts 2 and 4 of the molded product 1 shown in FIG. 1, a curved part 13 connecting the straight line parts 12 and 14, and a curved part 15 corresponding to approximately half of the bent part 5 shown in FIG. 1 are formed. The end of the curved part 15, which is away from the straight line part 14, is connected to the storage part 20, and a notch part 25a corresponding to the cross-sectional shape of the molded product 1 is formed at the connection part.

[0025] The accommodation section 20 is formed with a horizontal and flat bottom surface 27, and the piece 30 is placed on the bottom surface 27. A bolt hole 28 for fixing the rotational position of the piece 30 is formed in a part of the bottom surface 27. Although not shown in the drawings of this specification, a resin injection hole (not shown) for forming the molded product 1 is formed in the groove portion 11 of the concave side mold 10.

[0026] FIG. 4(B) is a perspective view showing the state in which the piece 30 is removed from the concave die 10. The piece 30 is a one-piece metal product, and is manufactured by performing cutting processing on a member prepared by forging or the like. The piece 30 is manufactured with a thickness (D2) smaller than the thickness (D1) of the concave die 10, and a groove portion 41 is formed in a size corresponding to the columnar portion 6 of the molded product 1 shown in FIG. 1 and about half of the bent portion 5. A female screw portion 38 for screwing with a fixing bolt (not shown) is formed in an area between the groove portion 41 and the tip arc surface 32, but not interfering with the groove portion 41. Although it is difficult to see in FIG. 4(B), the female screw portion 38 has an opening 38b formed on the back side, and the hole portion is formed as a non-through hole that does not reach the front surface. A female screw (not shown) is formed on the inner peripheral surface of the non-through hole. The size of this female screw is formed to be a size that screws with the male screw portion of the bolt (not shown) used to fix the piece 30.

[0027] At the radial tip of the piece 30, the tip arc surface 32 that comes into contact with the storage section 20 is formed into a gentle R shape, so that even if the angle of the piece 30 is changed, no unnecessary gap is created between the outer short side portion 22 and the tip arc surface 32, and therefore rattling of the piece 30 in the ±Y direction can be suppressed. The first side surface 31 and the second side surface 33 of the piece 30 are both flat and are substantially parallel surfaces. However, in order to allow the piece 30 to rotate slightly, the first side surface 31 and the second side surface 33 may be positioned such that the two surfaces are slightly separated from each other as they move from the side closer to the rotation center point 8 (see FIG. 3) to the side farther from the rotation center point 8. The inner peripheral surface 34 is a cylindrical surface with a gentle R shape that protrudes in the -Y direction. A cylindrical sliding surface 35 is formed on the -X side (the side closer to the rotation center point 8) of the inner peripheral surface 34. The sliding surface 35 is a cylindrical surface at a certain distance from the rotation center point 8, and a cutout portion 35a that becomes the opening end surface of the groove portion 41 is formed. Guide surface 25 (see Figure 3 or Figure 5(A) described below) and sliding surface 35 are configured as a set of inner and outer surfaces of approximately identical dimensions, so that their contact condition is maintained excellent even when the rotation angle changes, thereby increasing the degree of adhesion near the connection portion (sliding surface 25 and sliding surface 35) between the concave side mold 10 and the block 30, and significantly reducing the risk of burrs occurring in the molded product 1.

[0028] 5 is a perspective view of the die 10 and the piece 30, which are the same objects as those in FIG. 4, seen from a different angle. From FIG. 5(A), the arc shape of the guide surface 25 formed on the concave die 10 and the shape of the notch 15a which is the end of the groove 11 formed thereon can be understood. The accommodation section 20 for accommodating the piece 30 has a flat bottom surface 27, and the first long side 21, the outer short side 22, the second long side 23, the inner short side 24, and the guide surface 25, which are formed to intersect with the bottom surface 27 at right angles, are connected to the outer edge of the bottom surface 27, forming a large accommodation space with an opening on the upper side (+Z side). A bolt hole 28 for fixing the rotational position of the piece 30 is formed in a part of the bottom surface 27.

[0029] FIG. 5(B) is a perspective view of the piece 30. The outer end arc surface 32 of the piece 30 is a gently sloping cylindrical surface that protrudes radially outward in the w (+Y direction), and the corners 32a and 32b of the piece 30 with the first side surface 31 on both sides are connected by cylindrical surfaces with smaller radii of curvature. Comparing these corners 32a and 32b with the cylindrical corners 22a and 22b of the housing part shown in FIG. 5(A), the radius of curvature of the corners 22a and 22b is smaller, so that gaps are generated between the corners 22a and 22b and the corners 32a and 32b. However, the difference in these radii of curvature is merely due to the ease of machining the housing part 20 during cutting, and does not mean that gaps are necessary.

[0030] Fig. 6 is a perspective view of the convex mold 60 as seen from the back side. Since the molded product 1 (see Fig. 1) of this embodiment has a simple shape, the back side (the surface visible in Fig. 6) of the convex mold 60 facing the concave mold 10 is flat. Reference point 60a is joined to reference point 10a (see Fig. 2) of the concave mold 10. It is optional to provide the convex mold 60 with an additional shape or additional object that is formed so as not to affect the molding of the molded product 1. Furthermore, when the shape of the molded product 1 is complex, it is optional to form protrusions or grooves on the convex mold 60 side.

[0031] 7 is a top view of the concave die 10 according to the embodiment of the present invention with the bridge 30 removed. The bolt hole 28 is oval in the swing direction and is formed in an oval shape so that the bridge 30 can be fixed at any position between the counterclockwise position shown in FIG. 2 and the clockwise position shown in FIG.

[0032] FIG. 8 is a cross-sectional view at a plurality of cross-sectional positions of the concave mold 10 according to an embodiment of the present invention. FIG. 8(A) is a cross-section of the A-A portion in FIG. 7. As can be seen from the figure, the depth of the accommodating portion 20 is D2, which is formed deeper than the depth D of the groove portion 11. Further, a bolt hole 28 penetrating from the bottom surface portion 27 to the back surface 27 is formed in a part of the accommodating portion 20. The bolt hole 28 is formed as an oval hole 28a that is long in the rotational direction of the piece 30, and is configured such that a hexagonal socket bolt (not shown) can move slightly in the rotational direction of the piece 30. A large-diameter hole 28b for accommodating the head of the hexagonal socket bolt (not shown) is formed below the bolt hole 28 (the side close to the back surface 17). The large-diameter hole 28b may also be formed in an oval shape.

[0033] FIG. 8(B) is a cross-section of the B-B portion in FIG. 7. The groove depths D of the straight portion 12 and the curved portion 13 of the groove portion 11 are constant at any position. FIG. 8(C) is a cross-section of the C-C portion in FIG. 7. The depth of the accommodating portion 20 is D2, which is larger than the depth D of the groove portion 11. FIG. 8(D) is a cross-section of the D-D portion in FIG. 7. In the D-D cross-section of FIG. 7, since the accommodating portion 20 and the groove portion 11 are continuous, the difference between their depths D2 and D can be understood. Thus, in the concave mold 10 of this embodiment, the relationship is D < D2 < D1 (where D1 is the size (height) of the concave mold in the +Z direction).

[0034] FIG. 9 is a top view of the piece 30 according to an embodiment of the present invention, and FIG. 10 is a four-sided view of the piece 30. FIG. 10(A) is a side view (top view) of the piece 30 seen in the -Y direction shown in FIG. 9, (B) is a side view (left side view) seen in the +X direction, (C) is a side view (right side view) seen in the -X direction, and (D) is a side view (bottom view) seen in the +Y direction.

[0035] In FIGS. 10(A) to (C), the position of the female screw portion 38 formed on the piece 30 is indicated by a broken line. As can be seen from FIG. 10(A), the female screw portion 38 is a non-through hole that has an opening on the back surface 37 of the piece 30 but does not reach the surface 36. Further, as can be understood from FIGS. 10(B), (C) and FIGS. 4, 5, etc., the female screw portion 38 is formed at a position that does not interfere with the groove portion 41 of the piece 30.

[0036] Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments, and various modifications are possible within the scope of the present invention. For example, in the above embodiments, the shape of the molded product 1 has been described as a member having a plurality of linear columnar portions 2, 4, 6 and two bent portions 3, 5, but the shape of the molded product 1 is arbitrary, and in other molded products having a bent portion with an inner radius of curvature r1 and an outer radius of curvature r2, one side of the bent portion may be formed on the concave mold 10 side, and the other side may be formed on the movable piece 30 side. In addition, the concave mold 10 may be provided with a plurality of storage portions, and pieces that can rotate slightly within each of the storage portions may be provided. [Explanation of symbols]

[0037] 1 Molded object 2, 4, 6 columnar part 3, 5 Bent part 8 Rotation Center Point 9a, 9b (Pedestrian) Rotation Direction 10 Concave side mold 11 (First) Groove 12 Straight section 13 Curved section 14 Straight section 15 Curved section 15a Cutout 16 Surface 17 Back side 20 Storage unit 21 First long side 22 Outer short side 23 Second long side 24 Inner short side 25 Guide Surface 25a Cutout 27 Bottom part 28 Bolt Holes 28a Oval hole 28b Large diameter section 30 (movable) pieces 31 First aspect 32 Outer end arc surface 33 Second aspect 34 Inner surface 35 Sliding surface 35a Cutout 36 Surface 37 Back side 38 Female thread 41 (Second) Groove 45 Curved section 46 Straight section 60 Convex side mold 110 Mold 111 Groove

Claims

1. A mold for producing a molded product by injection molding, the mold having a concave mold and a convex mold arranged to sandwich a resin supplied from a resin injection port, a first groove portion for forming a molded product is formed in the concave mold, the concave-side die is provided with a movable piece that is rotatable with respect to the concave-side die within a predetermined range around a rotation center point as an axis and that has a second groove portion formed therein and that is continuous with the first groove portion; a fixing means for fixing a rotational position of the movable piece relative to the concave die; The mold is characterized in that, during the injection molding, the rotational position of the movable piece is fixed so that the molded product has a preform shape taking into account deformation of the molded product after molding.

2. 2. The mold according to claim 1, wherein an accommodation portion that forms a space for accommodating the movable piece is formed on the side of the concave mold facing the convex mold.

3. The movable piece is formed with an arc-shaped sliding surface that guides the rotation along the rotation center point, An arc-shaped guide surface is formed at a position corresponding to the sliding surface of the concave die, 3. The mold according to claim 2, wherein the fixed position of the movable piece is adjusted by rotating the movable piece so that the sliding surface slides against the guide surface.

4. The first groove portion is formed so as to intersect with the guide surface, The second groove portion is formed so as to intersect with the sliding surface, 4. The mold according to claim 3, wherein the first groove portion and the second groove portion are positioned so that their ends are continuous with each other regardless of the rotational position of the movable piece.

5. a through hole is formed from the outside of the concave mold to the accommodation portion; A bolt is attached from the outside through the through hole, 5. The mold according to claim 4, wherein the movable piece is formed with a female thread portion that screws together with the male thread of the bolt.

6. The mold according to claim 5, characterized in that the female screw portion formed on the movable piece is formed radially outwardly from the rotation center point and farther from the sliding surface, at a position not interfering with the second groove portion.

7. The mold according to claim 6, wherein the molded product includes a bent portion, and the sliding surface and the guide surface are arranged so as to intersect with the extending direction at the bent portion.

8. A resin molding method using a mold having a concave mold and a convex mold arranged to sandwich resin supplied from a resin injection port, the mold producing a molded product by blow molding, comprising the steps of: A movable piece having a nested structure that can move a fixed position by a small rotation angle is disposed on the concave side die, By adjusting the position of the movable piece in the direction opposite to the direction of deformation by an amount that takes into account deformation of the product after molding with resin, a groove portion is set by the mold having a shape that is slightly different from the dimensions of the product after molding; a molding method comprising: fixing the position of the movable piece; and then aligning the convex mold with the concave mold, and performing blow molding.

9. The concave die has a first groove for forming a molded product and an arc-shaped guide surface for guiding the rotation of the movable piece, The movable piece is formed with a second groove portion continuous with the first groove portion and an arc-shaped sliding surface for guiding rotation along a rotation center point, 9. The molding method according to claim 8, wherein, during the adjustment, the sliding surface of the movable piece is moved in a direction opposite to a deformation direction of the molded product after blow molding.

10. a through hole for fixing a rotational position of the movable piece relative to the concave die at an arbitrary position, and a bolt for screwing into a female screw portion formed on the movable piece through the through hole, 10. The molding method according to claim 9, wherein the rotation angle of the movable piece is adjusted by sliding the sliding surface against the guide surface, the position of the movable piece is fixed with the bolt, and then the blow molding is performed.

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