JP2012213941A - Method of manufacturing resin molding, and die for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a burr from remaining in a resin molding due to the whirl-in of a resin to the back side of a transfer sheet, in a method of manufacturing a resin molding.SOLUTION: In a transfer sheet arrangement process, a transfer sheet 10 is partially arranged on first cavity surfaces 22 by adjusting positions of ends 10a of the transfer sheet 10 on second cavity surfaces 23a, 23b with respect to a first die 20. In a molding process from a die clamping process to an extraction process, a resin molding having a decorative part of the transfer sheet 10 is molded by fitting a second die 40 to the first die 20. In a cutting process of tabs and a runner resin part, tabs formed on the second cavity surfaces 23 are cut from the resin molding formed on the first cavity surfaces 22.

Description

  The present invention relates to a method for producing a resin molded article using injection molding and an injection mold used for producing a resin molded article.

  Conventionally, in the injection molding method, as one of in-mold molding methods, for example, a simultaneous molding transfer method described in Patent Document 1 (Japanese Patent Laid-Open No. 2005-104007) is known. In the simultaneous molding transfer method, a transfer sheet is placed at a predetermined location on the cavity surface of a mold before clamping. And after mold clamping, resin is inject | emitted and a resin molded product is shape | molded, At the same time, a transfer layer is transcribe | transferred from the transfer sheet to the surface of a resin molded product.

  In such a molding simultaneous transfer method, since the appearance of the surface is important, the transfer layer is formed using a transfer sheet having a width wider than the entire width of the cavity surface.

  However, in order to form nails, ribs, bosses, etc. in the resin molded product, it may be necessary to form irregularities on the cavity surface of the mold where the transfer sheet is placed. Because of its thickness, it does not follow the uneven wall surface, making it difficult to use the transfer sheet. In such a case, it is conceivable to use a transfer sheet that is narrower than the entire width of the cavity surface to avoid a portion where unevenness is formed and to form a transfer layer only where there is no unevenness. However, when the transfer sheet is disposed only on a part of the cavity surface in this way, the resin wraps around from the end of the transfer sheet disposed on the cavity surface to the back side of the transfer sheet and causes a large variability on the surface of the resin molded product. May occur. A method of selecting only good products free of burrs from all the resin molded products that can be molded by allowing the possibility of resin wrapping around the back side of the transfer sheet is also conceivable. Worsens the manufacturing cost.

  An object of the present invention is to prevent burrs caused by the resin from flowing into the back side of the transfer sheet from remaining in the resin molded product in the method of manufacturing a resin molded product in which the transfer sheet is partially disposed on the cavity surface. An object of the present invention is to provide an injection mold suitable for a method for producing a resin molded product in which a transfer sheet is partially disposed on a cavity surface.

  Hereinafter, a plurality of modes will be described as means for solving the problems. These aspects can be arbitrarily combined as necessary.

  The manufacturing method of the resin molded product according to an aspect of the present invention includes a first cavity surface for molding the resin molded product, and a second cavity connected to the first cavity surface for forming a protrusion on the resin molded product. A transfer sheet disposing step of partially disposing the transfer sheet on the first cavity surface by aligning the end of the transfer sheet on the second cavity surface with respect to the first mold having the surface; A molding step for molding a resin molded product to which the transfer layer of the transfer sheet has been transferred together with the second mold, and a removal step for removing the protruding portion from the resin molded product are provided.

  In this method of manufacturing a resin molded product, even if the resin wraps around the back side of the transfer sheet at the end of the second cavity surface to form burrs, the burrs can be removed from the resin molded product together with the protruding portions. Thereby, even if the resin wraps around the back side of the transfer sheet, it is possible to prevent burrs from remaining on the resin molded product.

  At least one of the first mold and the second mold has a resin flow path for pouring resin into the first cavity surface, and the second cavity surface of the first mold is formed integrally with the resin flow path. The removal step may include a step of removing the protruding portion from the resin molded product together with the resin formed in the resin flow path.

  In this method of manufacturing a resin molded product, since the protruding portion is removed together with the resin formed in the resin flow path, the number of work steps is compared with the case where the resin formed in the resin flow path and the protruding portion are removed separately. Can be reduced. Further, since the volume of the resin to be removed is reduced as compared with the case where the resin in the resin flow path is formed separately from the protruding portion, the amount of resin required for each molding of the resin molded product can be reduced.

  The transfer sheet has an opening, the second mold has a resin flow path, and the first mold has a resin inlet for injecting resin into the second mold resin flow path. The transfer sheet arranging step includes a step of arranging the opening portion of the transfer sheet at the resin inlet and a step of arranging another transfer sheet different from the transfer sheet in the second mold, and the forming step is performed through the opening portion. It may include a step of injecting resin into the second type resin flow path from the first type resin injection port.

  In this method of manufacturing a resin molded product, the feed pitch of other transfer sheets can be reduced, and the materials of other transfer sheets can be reduced.

  In the first mold, the second cavity surface is provided at four locations around the first cavity surface, and in the transfer sheet arranging step, the positions of both end portions of the transfer sheet are aligned on the four second cavity surfaces. And a step of arranging the transfer sheet.

  In this method of manufacturing a resin molded product, even if the transfer sheet is arranged so as to cross the first cavity surface, the burr formed by the resin wrapping around the back side of the transfer sheet can be removed from the resin molded product. Thereby, the freedom degree of arrangement | positioning of a transfer sheet increases, and the kind of product which can apply this manufacturing method can be increased.

  The protrusion includes a first protrusion and a second protrusion formed by connecting two of the four second cavity surfaces, and the removing step includes the first protrusion and the second protrusion. The process of removing from a resin molded product may be included.

  In this method of manufacturing a resin molded product, the remaining burr at four locations can be prevented by cutting the first projecting portion and the second projecting portion, thereby reducing the number of steps for removing the projecting portion. Can do.

  An injection mold according to an aspect of the present invention is an injection mold for performing molding of a resin molded product and transfer of a transfer layer from a transfer sheet to a resin molded product at the time of injection molding. A first mold having a first cavity surface on which a sheet is partially disposed to form a resin molded product, and a second cavity surface connected to the first cavity surface to form a protrusion on the resin molded product; And a second mold that is matched with the first mold, and the first mold is provided with the second cavity surface at the position of the end of the transfer sheet that crosses the first cavity surface.

  When a resin molded product is manufactured using this injection mold, even if the resin wraps around the back side of the transfer sheet and burrs are formed, the burrs can be removed together with the protruding portions from the resin molded product. Thereby, even if the resin wraps around the back side of the transfer sheet, it is possible to prevent burrs from remaining on the resin molded product.

  In the first mold, the second cavity surface may be connected to the first cavity surface at the same depth as the first cavity surface.

  When a resin molded product is manufactured using this injection mold, the depth of the portion where the second cavity surface and the first cavity surface are connected is the same, so the first cavity surface on which the transfer sheet is arranged And no step at the boundary between the second cavity surface. For this reason, the transfer sheet does not float at the boundary between the first cavity surface and the second cavity surface, and the resin hardly enters the back side of the transfer sheet.

  At least one of the first mold and the second mold has a resin flow path for flowing resin into the first cavity surface, and the second cavity surface of the first mold flows resin into the first cavity surface. It may be provided integrally with the resin flow path.

  When a resin molded product is manufactured using this injection mold, the volume of the resin to be removed is reduced as compared with the case where the resin flow path and the second cavity surface are separately formed. The amount of resin required for the process can be reduced.

  An injection mold according to another aspect of the present invention is an injection mold for performing molding of a resin molded product and transfer of a transfer layer from a transfer sheet to the resin molded product at the time of injection molding, A first mold having a parting surface and a first cavity surface on which a transfer sheet is partially disposed to form a resin molded product, and a second mold matched to the first mold, The parting surface has an inclined portion that inclines toward the non-arrangement area where the transfer sheet is arranged from the arrangement area where the transfer sheet is arranged.

  When a resin molded product is manufactured using this injection mold, the end of the transfer sheet is placed on the inclined portion that is inclined from the transfer sheet placement area toward the non-placement area so as to approach the parting surface of the first mold. By disposing the portion, the gap formed in the portion surrounded by the end portion of the transfer sheet and the first mold and the second mold becomes very small. Thereby, even if the transfer sheet is partially disposed on the first cavity surface, it is possible to prevent the resin burr from being formed by the resin leaking from the end of the transfer sheet.

  An injection mold according to another aspect of the present invention is an injection mold for performing molding of a resin molded product and transfer of a transfer layer from a transfer sheet to the resin molded product at the time of injection molding, A first mold having a first cavity surface on which a transfer sheet is partially disposed to form a resin molded product, and a second mold matched to the first mold, wherein the first mold or the second mold is: The first mold has a resin flow path for pouring resin into the first cavity surface, and the first mold has a fitting structure for pressing the transfer sheet across the resin flow path at the boundary of the transfer sheet arrangement region, The type 2 has a fitted structure that is fitted to the fitting structure, and the resin flow path enters between the fitting structure and the fitted portion of the fitted structure and enters the transfer sheet arrangement region. Change the direction in the longitudinal direction of the transfer sheet within the placement area, and connect the first cavity surface to the center of the placement area. One is intended.

  When a resin molded product is manufactured using this injection mold, the transfer sheet is held in a state where the transfer sheet is pulled in the vicinity of the resin flow path by the fitting between the fitting structure and the fitting structure. It is done. Accordingly, the transfer sheet is prevented from being pushed and moved by the resin flowing through the resin flow path, and the resin is prevented from entering the back side of the transfer sheet due to the movement of the transfer sheet. In addition, since the resin flows into the first cavity surface from the vicinity of the center of the transfer sheet, the force applied to both ends of the transfer sheet is the same, the transfer sheet is less likely to become wrinkles, and the resin wraps around the back side of the transfer sheet. It becomes difficult.

  ADVANTAGE OF THE INVENTION According to this invention, in manufacture of the resin molded product in which a transfer sheet is partially arrange | positioned to a cavity surface, it can prevent that the burr | flash by resin going around to the back side of a transfer sheet remains in a resin molded product.

The flowchart which shows the outline | summary of the manufacturing process of the resin molded product which concerns on 1st Embodiment. The perspective view of the 1st type | mold and 2nd type | mold in a transfer sheet arrangement | positioning process. The top view which shows the external appearance of a resin molding. The end view of the resin molded product cut | disconnected by the II line | wire of FIG. The expansion perspective view which expanded the parting surface of the 1st type of Drawing 2. The enlarged perspective view which expanded the parting surface of the 2nd type of Drawing 2. The enlarged plan view which expanded the parting surface of the 1st type | mold of FIG. FIG. 8 is an end view of the first mold and the second mold that have been clamped and cut at a line II-II in FIG. 7. (A) The schematic diagram for demonstrating the flow of the resin of the 1st type | mold side in an injection process, (b) The schematic diagram for demonstrating the flow of the resin of the 2nd type | mold side in an injection process. FIG. 9A is an end view taken along line III-III in FIG. 9A, and FIG. 9B is an end view for explaining the flow of resin in the end view in FIG. IV-IV sectional view taken on the line in FIG. (A) Partial enlarged cross-sectional view of the transfer sheet disposed at the stepped portion, (b) Partial enlarged cross-sectional view of the transfer sheet disposed at the stepped portion, (c) Displaced at the stepped portion. The partial expanded sectional view of a transfer sheet, (d) The partial expanded sectional view of the transfer sheet arrange | positioned at the inclination part. The schematic diagram for demonstrating the phenomenon in which resin turns to the back of a transfer sheet with the flow of the resin by the side of the 2nd type | mold in an injection process. The partial enlarged plan view of the 1st type parting surface which concerns on 2nd Embodiment. The partial enlarged plan view of the 2nd type parting surface which concerns on 2nd Embodiment. The figure which shows the cross section in the VV line | wire of FIG.14 and FIG.15. FIG. 3 is a partial enlarged plan view showing a transfer pitch of a transfer sheet in the first embodiment.

<First Embodiment>
(1) Outline of Manufacturing Process of Resin Molded Product Hereinafter, a manufacturing process of a resin molded product by the simultaneous molding transfer method according to the first embodiment of the present invention will be described with reference to FIG.

  First, in the transfer sheet arranging step (step S1) in FIG. 1, as shown in FIG. 2, the transfer sheets 10 and 15 are placed between the molds (first mold 20 and second mold 40) opened. Is placed. The transfer direction of the transfer sheets 10 and 15 shown in FIG. 2 is that the transfer sheet 10 is in the horizontal direction and the transfer sheet 15 is in the vertical direction. The arranged transfer sheets 10 and 15 are fixed so as not to move by a clamp or the like which will be described later. In FIG. 2, the description of a suction hole and a horizontal groove, which will be described later, is omitted in order to avoid the figure from being difficult to see.

  The base films constituting these transfer sheets 10 and 15 are, for example, polyester resins, vinyl chloride resins, acrylic resins, polycarbonate resins, polypropylene resins, polyethylene resins, polyurethane resins, polystyrene resins, acetate resins. It is made of a material selected from a resin, a polyamide-based resin, and the like. The thickness of the base film is preferably selected from the range of 5 μm to 5 mm. When the thickness of the base film is less than 5 μm, the transfer sheet has a low rigidity and easily wrinkles. On the other hand, if it is thicker than 5 mm, the rigidity becomes so high that it becomes difficult to handle, and it becomes difficult to follow the curved surface such as the first cavity surface 22 in particular.

  Next, mold clamping is performed, and the parting surface 41 of the second mold 40 is aligned with the parting surface 21 of the first mold 20 (step S2). Then, molten resin is injected into the clamped first mold 20 and second mold 40, and the first cavity surface 22 and the second cavity surfaces 23 a and 23 b of the first mold 20 are passed through the resin flow paths 24 and 44. The resin is poured into the cavity surrounded by the cavity surface 42 of the second mold 40 (step S3).

  In the next pressure holding step, a predetermined pressure is continuously applied so that the resin injected into the cavity maintains an appropriate density (step S4). In the cooling process following the pressure holding process, cooling is performed by the cooling function of the mold for a preset cooling time in order to cure all the molten resin in the cavity (step S5).

  Next, in the mold opening process, the mold is opened and the second mold 40 is separated from the first mold 20 (step S6). When the mold is opened, the resin molded body cooled and solidified is ejected by a projecting cylinder (not shown), and the resin molded body is released from the first mold 20 and the second mold 40 (step). S7).

  When the resin molded body is taken out of the mold, the injection molding by the mold returns to step S1 and the steps after step S1 are repeated. On the other hand, since the resin molded body has a runner resin portion attached to the resin molded product, an unnecessary resin portion such as a runner resin portion is cut in the next tab and runner resin portion cutting step (step S8). Is cut to obtain a resin molded product.

(2) Transfer Sheet Arrangement Step The transfer sheet arrangement step (step S1) described above will be described. First, a resin molded product that is a transfer target of the transfer layer will be described with reference to FIG. To do.

  FIG. 3 is a plan view showing a resin molded body molded using the first mold 20 and the second mold 40 shown in FIG. The resin molded body 60 shown in FIG. 3 includes two resin molded products 61 and 62, tabs 63 a and 63 b, and a runner resin portion 64. The tabs 63a and 63b and the runner resin portion 64 are unnecessary portions for the resin molded products 61 and 62, and are removed in a tab and runner resin portion cutting step (step S8) described later. The resin molded products 61 and 62 are back covers that cover, for example, a battery storage unit of a mobile phone.

  The resin molded product 61 is provided with a decoration portion 65 such as an explanatory note. The decoration portion 65 is formed of a transfer layer transferred from the transfer sheet 10 described above. The transfer layer for forming the decoration part 65 is continuously formed on the base film along the feeding direction of the transfer sheet 10. For each shot of injection molding of the resin molded products 61 and 62, the transfer sheet 10 is sent in the direction of the arrow to position the transfer layer. For the transfer layer of the transfer sheets 10 and 15, for example, a material selected from a polyester resin, an acrylic resin, a vinyl resin, a nitrified cotton resin, a urethane resin, a chlorinated rubber resin, or the like is used. When the layer is a metal film layer, a material selected from aluminum, chromium, copper, nickel, indium, tin, silicon oxide and the like is used. The film thickness of the transfer layer is preferably selected from the range of 0.5 to 50 μm in consideration of design properties and drying after printing. When the transfer layer is a metal film layer, the film thickness of the transfer layer is preferably selected from the range of 150 to 1200 angstroms in consideration of the design properties and the ease of occurrence of cracks.

  FIG. 4 shows an end surface cut along a line II in FIG. As can be seen from FIG. 4, the resin molded products 61 and 62 of FIG. 3 are provided with claws 65, 66, and 67 as attachment structures for attachment to the main body of the mobile phone. Generally, the mounting structure of a resin molded product includes ribs and bosses in addition to claws. The transfer sheet 10 cannot be placed where there are irregularities for forming such claws 65, 66, 67. Therefore, the width of the transfer sheet 10 must be narrower than the planar shape of the resin molded body 60, particularly the resin molded products 61 and 62. The width of the transfer sheet 10 is narrower than that of the first cavity surface 22, and the transfer sheet 10 is disposed so as to avoid the uneven portions of the first cavity surface 22 for forming the claws 65, 66, 67 and the like.

  FIG. 5 shows an enlarged view of the parting surface 21 of the first mold 20. The transfer sheet 10 fed by the first pitch by a sheet feeding device (not shown) is sucked and held in the suction holes 31 using a vacuum pump (not shown). The suction hole 31 is formed in a laterally extending groove 32 surrounding the first cavity surface 22 and the second cavity surfaces 23a and 23b. The transfer sheet 10 sucked and held is held by a clamp 30. The clamp 30 presses the transfer sheet 10 against the parting surface 21 when holding the transfer sheet 10. On the other hand, when the transfer sheet 10 is fed, the transfer sheet 10 is released when the clamp 30 is separated from the parting surface 21.

  As can be seen from FIG. 5, the transfer sheet 10 passes through the second cavity surfaces 23a and 23b, and is arranged so that the end 10a crosses the boundary between the parting surface 21 and the second cavity surfaces 23a and 23b. In other words, the boundary between the parting surface 21 and the second cavity surfaces 23 a and 23 b crosses the transfer sheet 10 perpendicular to the longitudinal direction of the transfer sheet 10. Further, one of the end portions 10 a of the transfer sheet 10 crosses over the concave portion 26.

  FIG. 6 shows an enlarged view of the parting surface 41 of the second mold 40. As shown in FIG. 6, the transfer sheet 15 has a wide width that covers the entire cavity surface 42. In this way, the width of the transfer sheet 15 is wider than the cavity surface 42, for example, the metallic luster is generated on the entire front side of the resin molded products 61 and 62 (the side opposite to the back side where the decorative portion 65 is formed). This is because a decorative portion (not shown) is formed.

  Also for the transfer sheet 15, the transfer sheet 15 is sent in the direction of the arrow for each shot of the injection molding of the resin molded products 61 and 62, and the transfer layer is positioned. The transfer sheet 15 fed by the second pitch by a sheet feeding device (not shown) is sucked and held in the suction holes 51 using a vacuum pump (not shown). The suction hole 51 is formed in a lateral groove 52 surrounding the first cavity surface 42. The transfer sheet 15 sucked and held is held by a clamp 50. The clamp 50 presses the transfer sheet 15 against the parting surface 41 when it holds the transfer sheet 15. On the other hand, when the transfer sheet 15 is fed, the transfer sheet 15 is released when the clamp 50 is separated from the parting surface 41.

(3) Mold Clamping Process In the mold clamping process (step S2), the parting surfaces 21 and 41 of the first mold 20 and the second mold 40 are aligned. At the time of mold clamping, the concave portion 26 of the parting surface 21 and the convex portion 46 of the parting surface 41 shown in FIGS. 5 and 6 are fitted. Since the end portion 10a of the transfer sheet 10 is arranged so as to cross the concave portion 26 and the convex portion 46, when the concave portion 26 and the convex portion 46 are fitted, the vicinity of the end portion 10a is fixed in a pulled state. The end portion 10 a of the transfer sheet 10 to be fixed crosses the resin flow path 44 downstream of the resin injection port 45. If the end portion 10a of the transfer sheet 10 is not fixed in a pulled state, the resin flows from the end portion 10a of the transfer sheet 10 into the back of the transfer sheet 10 and moves. One of the causes.

  FIG. 7 shows a planar shape around the cavity surfaces 22 and 23 of the first mold 20. Further, FIG. 8 schematically shows an end surface cut at the position of the line II-II in FIG. 7 in a state where the first mold 20 and the second mold 40 are combined. In FIG. 8 and FIG. 12, which will be described later, the ratio of each part is not correctly shown to scale, and a deformed end face shape is shown to make the inclined part easy to see. A region Ar1 indicated by hatching in FIG. 7 is a region where the inclined portion 27 shown in FIG. 8 is formed. The inclined portion 27 is formed so that the end portion 10a of the transfer sheet 10 is positioned substantially at the center in the width direction in the sectional view.

  In the cross section of FIG. 8, the area Ar <b> 2 is an area where only the transfer sheet 15 is arranged. With the parting surfaces 21 and 41 in contact with each other, a gap having a height D1 is formed between the sheet arrangement surface 28a of the first mold 20 and the sheet arrangement surface 48 of the second mold 40 excluding the inclined portion 27 in the region Ar2. Is formed. This height D1 substantially corresponds to the thickness of the transfer sheet 15.

  Further, the area Ar3 is an area where both the transfer sheets 10 and 15 are arranged. That is, the width of the area Ar <b> 3 shown in FIG. 8 corresponds to the width of the transfer sheet 10. In this region Ar3, the height between the sheet arrangement surface 28b of the first mold 20 and the sheet arrangement surface 48 of the second mold 40 excluding the inclined portion 27 in a state where the parting surfaces 21 and 41 are in contact with each other. A gap D2 is formed. This height D2 substantially corresponds to the sum of the thickness of the transfer sheet 10 and the thickness of the transfer sheet 15.

(4) Injection Step FIG. 9 schematically shows the injected resin and its flow. FIG. 9A shows the state of the first mold 20 side when the first mold 20 and the second mold 40 are combined and the resin is injected, and FIG. 9B shows the state. The state of the second mold 40 side is shown. An arrow 80 extending from the resin injection port 45 indicates the flow of the injected resin. In the state shown in FIG. 9, the leading portion of the injected resin 81 reaches the cavity surfaces 22 and 42.

  By the time the state shown in FIG. 9 is reached, the resin that has advanced through the runners 24a and 44a of the resin flow paths 24 and 44 changes its direction in the orthogonal direction in order to enter the fan gates 24b and 44b. Then, the first cavity surfaces 22 and 42 are reached via the fan gates 24b and 44b and the second cavity surface 23a. That is, when the fan gates 24 b and 44 b and the second cavity surface 23 a enter the first cavity surfaces 22 and 42, the resin is necessarily sandwiched between the transfer region 10 and the transfer sheets 10 and 15. Flowing. In FIG. 9, the resin travel locus 82 is indicated by a two-dot chain line.

  FIG. 10 shows a cross section taken along line III-III of FIG. 9, FIG. 10 (a) is a partial cross-sectional view showing a cross-sectional state before the resin flows, and FIG. 10 (b) is a flow of the resin. It is a fragmentary sectional view which shows the subsequent cross-sectional state. As the resin flows in, as shown in FIG. 10B, a phenomenon that the transfer sheet 10 is separated from the second cavity surface 23b in the vicinity of the end 23c of the second cavity surface 23b sometimes occurs. In such a case, resin enters between the separated transfer sheet 10 and the second cavity surface 23b. The resin that enters between the transfer sheet 10 and the second cavity surface 23b becomes a large burr. However, even if such a phenomenon occurs that the resin wraps around the back side of the transfer sheet 10, the burr due to the back of the resin does not reach the boundary 86 between the first cavity surface 22 and the second cavity surface 23b. Therefore, as will be described later. If the tab 63b formed on the second cavity surface 23b is cut off, the burr generated by the reverse side phenomenon can be removed. Similarly to the tab 63b formed by the second cavity surface 23b, the tab 63a formed by the second cavity surface 23a is separated from the resin molded products 61 and 62, whereby the burrs are formed on the resin molded products 61 and 62. The effect which prevents remaining is produced.

  As shown in FIG. 9A, at the end portion 10a of the transfer sheet 10 on the first cavity surface 22, the injected resin 81 always moves from the arrangement area Ar3 of the transfer sheet 10 to the non-arrangement area Ar2. It flows toward.

(5) Cutting process In the cutting process (step S8), the tabs 63a and 63b and the runner resin portion 64 shown in FIG. 3 are cut. The tabs 63a and 63b and the runner resin portion 64 are cut off simultaneously. As described above, since the first cavity surface 22 and the second cavity surface 23 have the same depth, there is no step in the boundary between the first cavity surface 22 and the second cavity surface 23, which may be difficult to distinguish. Here, the tabs 63a and 63b are cut based on the outer periphery 68 of the resin molded products 61 and 62. 11 is a cross-sectional view showing a cross section taken along line IV-IV in FIG. It can be seen from FIG. 11 that there is a step that can determine the position of the outer periphery 68. A cut surface 69 cuts the outer periphery 68 as a reference.

  Since the second cavity surface 23 is used as a part of the resin flow path 24, the tab 63 a is shared with the runner resin portion 64. Therefore, if the tab 63a is cut, the runner resin portion 64 is also removed at the same time.

<Modification 1>
In the above embodiment, the case where the transfer layer is transferred to both the front and back surfaces of the resin molded products 61 and 62 by the transfer sheets 10 and 15 has been described. However, molding using a transfer sheet having a narrow width like the transfer sheet 10 The simultaneous transfer method can also be applied when transferring to either the front surface or the back surface of the resin molded product.

  In the above-described embodiment, the case where one transfer sheet 15 is wider than the entire width of the resin molded products 61 and 62 has been described. However, both transfer sheets are as narrow as the transfer sheet 10 described above. The present invention can also be applied to a case where a decorative portion is provided on a part of each of the first cavity surfaces of both the first type and the second type.

<Modification 2>
In the above embodiment, the case where two resin molded products 61 and 62 are simultaneously formed in a set of molds (first mold 20 and second mold 40) has been described. However, the number of resin products to be molded simultaneously with a set of molds may be one or three or more.

  Moreover, although the case where the same resin molded products 61 and 62 are formed by one set of the first mold 20 and the second mold 40 has been described, a plurality of types of resin molded products having different shapes are formed by one set of molds. It can also be applied.

<Modification 3>
In the above embodiment, the feeding directions of the transfer sheets 10 and 15 are the horizontal direction and the vertical direction, respectively. However, the feeding direction of the transfer sheet is not limited to the example shown in FIG. Can be changed as appropriate.

<Features>
(1) The first mold 20 has a first cavity surface 22 for molding the resin molded products 61 and 62 on the parting surface 21 and a tab 63a and 63b (protrusion) on the resin molded product. The first cavity surface 22 has a second cavity surface 23 connected to the first cavity surface 22.

  In the transfer sheet arranging step (step S1), the end of the transfer sheet 10 is positioned on the second cavity surface 23 with respect to the first mold 20 so that the transfer sheet 10 is partially on the first cavity surface 22. Arranged. In other words, aligning the position of the end portion 10a of the transfer sheet 10 on the second cavity surface 23 means that the end portion 10a of the transfer sheet 10 is located at the locations P1, P2, P3, and P4 shown in FIG. It intersects the boundary between the second cavity surface 23 and the parting surface 21.

  In the molding process from the mold clamping process (step S2) to the take-out process (step S7), the resin on which the decorative portion 65 (transfer layer) of the transfer sheet 10 is transferred by aligning the second mold 40 with the first mold 20 Molded products 61 and 62 are molded. In the tab and runner resin portion cutting step (removing step: step S8), the tabs 63a and 63b (protruding portions) are cut (removed) from the resin molded products 61 and 62.

  As an injection mold used in such a manufacturing process, the first mold 20 has a second cavity surface 23 for forming tabs 63a and 63b (protrusions) on the resin molded products 61 and 62. The second cavity surface 23 is preferably disposed at the position where the end portion 10 a of the transfer sheet 10 crosses the first cavity surface 22. The place where the transfer sheet 10 is partially disposed is a place including the position of the decorating portion 65 that avoids unevenness for forming the claws 65, 66, 67, ribs, bosses, and the like.

  In the method of manufacturing a resin molded product described above, the transfer sheet 10 is disposed at the center of the first cavity surface 22, and the transfer sheet 10 is not disposed on both sides of the transfer sheet 10 on the first cavity surface 22. There is a non-arrangement region Ar2. However, the form of partial arrangement is not limited to this form. In the transfer sheet arranging step, the transfer sheet 10 is partially arranged on the first cavity surface 22 by aligning only the position of one end 10 a of the transfer sheet 10 on the second cavity surface 23. A non-arrangement region of the transfer sheet 10 may be provided only on one side of the first cavity surface with the end 10 a as a boundary, and the other side may be covered with the transfer sheet 10.

  In the manufacturing method of the resin molded product described above, as a removing step, the tabs 63a and 63b are removed from the resin molded product 61 and 62 by cutting, but the tabs 63a and 63b (protruding portions) are removed from the resin molded product 61 and 62. ) Is preferably mechanically removed. As a method of removing mechanically, there is a method of breaking apart other than cutting.

  In this method of manufacturing a resin molded product, even if the resin wraps around the back side of the transfer sheet 10 to form burrs, the burrs can be removed from the resin molded products 61 and 62 together with the tabs 63a and 63b (protrusions). Thereby, even if the resin wraps around the back side of the transfer sheet 10, it is possible to prevent burrs from remaining on the resin molded products 61 and 62. The protruding portion formed on the second cavity surface is not limited to the tab, and may be a member protruding from the resin molded product so that it can be removed from the resin molded product after molding.

  (2) In the first mold 20, the second cavity surface 23 between the resin channel 24 and the first cavity surface 22 is formed integrally with the resin channel 24 for flowing resin into the first cavity surface 22. Has been. In the cutting step (step S8: removal step), the tab 63a (protruding portion) is cut (removed) from the resin molded products 61 and 62 together with the runner resin portion 64 (resin formed in the resin flow path). .

  Therefore, the number of work steps can be reduced as compared with the case where the runner resin portion 64 and the tab 63a are removed separately. Further, since the volume of the resin to be removed is reduced as compared with the case where the runner resin portion 64 and the tab 63a are separately formed, the amount of resin required for molding the resin molded products 61 and 62 can be reduced.

  In the said embodiment, both the 2nd cavity surface 23 and the resin flow paths 24 and 44 of the 1st type | mold 20 and the 2nd type | mold 40 are integrated. However, the resin flow path integrated with the second cavity surface 23 does not have the resin flow path 44 of the second mold 40, and only the second cavity surface 23 and the resin flow path 24 of the first mold 20 are integrated. The case may be a case where the resin flow path 24 of the first mold 20 is not provided and only the second cavity surface 23 and the resin flow path 44 of the second mold 40 are integrated.

  (3) The first mold 20 is provided with the second cavity surface 23 at four locations P1, P2, P3, P4 around the first cavity surface 22. In the transfer sheet arranging step (step S1), the positions of both end portions 10a of the transfer sheet 10 are aligned on the second cavity surfaces 23 at the four places P1, P2, P3, and P4.

  In this method of manufacturing a resin molded product, even if the transfer sheet 10 is arranged so as to cross the first cavity surface 22, burrs formed by the resin wrapping around the back side of the transfer sheet 10 are formed from the resin molded products 61 and 62. Can be removed. Thereby, the freedom degree of arrangement | positioning of the transfer sheet 10 increases, and the kind of product which can apply this manufacturing method can be increased.

  In the above embodiment, one second cavity surface 23a corresponds to two places P1 and P2, and the other second cavity surface 23b corresponds to the other two places P3 and P4. However, it is not necessary to correspond to two locations on one second cavity surface, and one second cavity surface is provided at one location, and four second locations respectively corresponding to four locations P1, P2, P3, and P4. A cavity surface may be provided.

  (4) The tabs 63a and 63b (protrusions) are tab 63a (first protrusion) and tab 63b (second protrusions) formed by connecting two portions of each of the four second cavity surfaces. In the cutting process (step S8), the two tabs 63a and 63b are cut from the resin molded products 61 and 62.

  In this method of manufacturing a resin molded product, the remaining burr can be prevented by cutting the tabs 63a and 63b (the first projecting portion and the second projecting portion) at two locations P1, P2, P3, and P4. It is possible to reduce the man-hours for removing the tabs (protrusions).

  (5) In the first mold 20, the second cavity surfaces 23 a and 23 b are connected to the first cavity surface 22 at the same depth as the first cavity surface 22.

  Since the depth of the portion where the second cavity surfaces 23a, 23b and the first cavity surface 22 are connected is the same, there is a step at the boundary between the first cavity surface 22 where the transfer sheet 10 is disposed and the second cavity surfaces 23a, 23b. I can't. Since the transfer sheet 10 does not float at the boundary between the first cavity surface 22 and the second cavity surfaces 23a and 23b, the resin does not easily enter the back side of the transfer sheet 10.

  In order for the first cavity surface and the second cavity surface to be connected at the same depth, the first cavity surface and the second cavity surfaces 23a and 23b do not need to be parallel, and may be smoothly inclined, It may be smoothly curved. However, it is preferable that the boundary between the first cavity surface and the second cavity surface is formed on one plane as in the above embodiment.

  (6) The parting surface 21 of the first mold 20 is located at the position of the end portion 10a of the transfer sheet 10 across the first cavity surface 22, and is not arranged from the arrangement region Ar3 where the transfer sheet 10 is arranged. It has the inclination part 27 which inclines toward.

  As described above, when the transfer sheet 10 is partially disposed on the first cavity surface 22, not only the back of the resin to the transfer sheet 10 but also the end of the transfer sheet 10 due to the thickness of the transfer sheet 10. Resin burrs easily occur in 10a. When the first mold 20 and the second mold 40 having the inclined portion 27 are used, such resin burrs that are easily formed on the end portion 10a of the transfer sheet 10 can be prevented. Providing a resin molded product with a more beautiful appearance by preventing the generation of not only resin burrs caused by wrapping around the back side of the transfer sheet 10 but also resin burrs formed due to the end 10a of the transfer sheet 10. Can do.

  The effect by this inclined part 27 is demonstrated using FIG. FIG. 12A shows a state where burrs are prevented from occurring at the end portion 10 a of the transfer sheet 10 when the sheet arrangement surface 28 b is formed by the step of the first mold 20. According to the conventional method, as shown in FIG. 12A, it is conceivable to form a step to prevent a resin burr caused by the end portion 10a. However, when a step is formed on the parting surface 21, a gap 90 is formed between the step and the end 10a unless the end 10a is in contact with the step as shown in FIG. As a result, resin leaks from the gap 90 and causes resin burrs. Also, as shown in FIG. 12C, the transfer sheet 10 is sandwiched between the sheet placement surface 28a at the upper part of the step and the sheet placement surface 48 of the second mold 40, and the gap 91 and 92 are generated. If resin leaks from these gaps 91 and 92, it will cause resin burrs.

  When the inclined portion 27 is provided, as shown in FIG. 12D, even if the arrangement position of the transfer sheet 10 varies somewhat, the formed gap 93 becomes very small, and the resin is It can be made smaller than the gap required to flow out. Therefore, the generation of resin burrs due to the thickness of the transfer sheet 10 can be prevented. The inclined portion may not only change in a straight line but may change in a curved line or a broken line, and gradually changes from the height of the sheet arrangement surface 28b to the height of the sheet arrangement surface 28a. Just do it.

  (7) The first mold 20 and the second mold 40 have a resin flow path 44 for pouring resin into the first cavity surfaces 22 and 42. In the said embodiment, although the 2nd type | mold 40 has the resin flow path 44, the 1st type | mold 20 may have a resin flow path.

  The first mold 20 has a concave portion 26 (fitting structure) for pressing the transfer sheet 10 across the resin flow path 44 at the boundary (arrangement position of the end 10a) of the arrangement area A1 of the transfer sheet 10. The 2 type | mold 40 has the convex part 46 (fit structure).

  The first type resin flow path is between two fitting locations where the two concave portions 26 and the two convex portions 46 are fitted (between the fitting structure and the fitting portion of the fitted structure). It passes through the arrangement area Ar3 of the transfer sheet 10 and changes its direction in the longitudinal direction of the transfer sheet 10 in the arrangement area Ar3, and has a shape connected to the first cavity surface 22 in the vicinity of the central portion C1 of the arrangement area.

  When a resin molded product is manufactured using this injection mold, the transfer sheet 10 is pulled and fixed in the vicinity of the resin flow path 44 by the fitting of the two concave portions 26 and the two convex portions 46. . Accordingly, a phenomenon in which the transfer sheet 10 is pushed and moved by the resin flowing through the resin flow path 44 is prevented, and the resin is prevented from entering the back side of the transfer sheet 10 due to the movement of the transfer sheet 10. Further, since the resin is poured from the vicinity of the central portion C1 of the transfer sheet 10 toward the first cavity surface 22, a force pressing the transfer sheet 10 against the first cavity surface 22 is generated at the end portion 10a of the transfer sheet 10, and both ends are provided. A similar force works in the portion 10a. Therefore, the transfer sheet 10 is less likely to become wrinkles, and the resin is less likely to go around the back side of the transfer sheet 10.

  For example, FIG. 13 shows a case where the conventional gate position is applied as it is, and the resin is poured into the first cavity surface 44 from the non-arrangement area Ar2 outside the arrangement area Ar3 of the transfer sheet 10. . When such a gate arrangement is used, a force that pushes from the end portion 10 a of the transfer sheet 10 toward the center portion causes the leading portion of the resin 81 to act on the end portion 10 a of the transfer sheet 10. As a result, the end portion 10 a of the transfer sheet 10 is pulled, and a gap is formed at a position P <b> 5 where the transfer sheet 10 crosses the first cavity surface 44, so that the resin easily turns around the back side of the transfer sheet 10. Compared with the configuration of FIG. 13 as described above, it can be seen that the configuration of the first mold 20 and the second mold 40 in which the resin flow paths 24 and 44 as shown in FIG. 9 are formed is superior. .

  When the second cavity surfaces 23a and 23b are provided, the injection mold having the configuration described in the above (6) and (7) is free of resin burrs such as removal of burrs by the resin that wraps around the back side. It can be removed sufficiently. However, even when the second cavity surfaces 23 a and 23 b are not provided, the above-described configurations (6) and (7) can be applied. Even in this case, the transfer sheet 10 is partially placed in the first cavity 22. There is an effect of preventing the generation of burrs caused by the arrangement.

Second Embodiment
The method for manufacturing a resin molded product according to the second embodiment of the present invention also includes the same steps as steps S1 to S8 of the method for manufacturing a resin molded product according to the first embodiment shown in FIG. The resin molded product manufacturing method according to the second embodiment differs from the resin molded product manufacturing method of the first embodiment mainly in the form of the transfer sheet used and the shape of the mold.

  As shown in FIG. 14, in the transfer sheet 10A, an opening 11 is formed at an equal position from both ends 10Aa, that is, at the center of the transfer sheet 10A. In the state where the transfer sheet 10A is fixed by the clamp 30 in the transfer sheet arranging step (step S8), the resin injection port 25 of the hot runner 24Aa of the first mold 20A is located in the opening 11 (see FIG. 14). .

  FIG. 16 shows a cross section of the clamped mold (first mold 20A and second mold 40A) cut along the line VV in FIGS. In the state where the mold is clamped in the mold clamping step (step S2), the resin injection port 25 of the hot runner 24Aa is arranged to face the runner 44Aa of the second mold 40A shown in FIG.

  Accordingly, in the injection step (step S3), the molten resin is injected from the hot runner 24Aa of the first mold 20A to the runner 44Aa of the second mold 40A through the opening 11 of the transfer sheet 10A.

  As shown in FIG. 16, the periphery of the resin inlet 25 of the hot runner 24 </ b> Aa is flat, and wrinkles and the like are less likely to lean on the transfer sheet 10 </ b> A. Therefore, the resin injected from the hot runner 24Aa initially flows exclusively through the resin flow path 44A of the second mold 40A. When flowing from the runner 44Aa of the second mold 40A to the fan gate 44Ab, it also starts flowing to the fan gate 24Ab of the first mold 20A. A second cavity surface 23a is formed integrally with the fan gate 24Ab of the first mold 20A.

<Features>
In this way, the transfer sheet 10A is provided with the opening 11, and the transfer sheet 15 (another transfer sheet) is configured by injecting resin from the opening 11 into the resin flow path 44A of the second mold 40A. ) Feed pitch is reduced. The reduction of the feeding pitch of the transfer sheet 15 will be described by comparing FIGS. 15 and 17. As shown in FIG. 17, when the resin injection port 45 is arranged so as to be shifted in the feeding direction of the transfer sheet 15 from the first cavity surface 42, the resin injection port 45 is not affected by the heat of the molten resin. A feed pitch Pt2 for feeding the transfer sheet 15 is required. On the other hand, as shown in FIG. 15, if the transfer sheet 15 is within the range of the first cavity 42 in the feed direction, the transfer is performed by the feed pitch Pt1 that is not affected by the resin injected into the first cavity 42. The sheet 15 may be sent. As a result, the feed pitch Pt2 when using the first mold 20 and the second mold 40 is greater than the feed pitch Pt1 when using the first mold 20A and the second mold 40A, and the transfer sheet 15 can be reduced. .

  Since the fan gate 20b of the first mold 20A is formed integrally with the second cavity 23a, it is the same as in the first embodiment that the back of the resin can be prevented. Also, the first mold 20A of the second embodiment is provided with an inclined portion similar to the inclined portion 27 of the first mold 20 similarly to the first mold 20 of the first embodiment, and has the same effect.

10, 10A, 15 Transfer sheet 20, 20A First mold 22, 42 First cavity surface 23a, 23b Second cavity surface 40, 40A Second mold

JP 2005-104007 A

Claims (10)

For a first mold having a first cavity surface for molding a resin molded product and a second cavity surface connected to the first cavity surface for forming a protrusion in the resin molded product, the second A transfer sheet arranging step of partially arranging the transfer sheet on the first cavity surface by aligning the position of the end of the transfer sheet on the cavity surface;
A molding step of molding a resin molded product onto which the transfer layer of the transfer sheet is transferred by combining the second mold with the first mold
A removal step of removing the protrusion from the resin molded product;
A method for producing a resin molded product. At least one of the first mold and the second mold has a resin flow path for pouring resin into the first cavity surface,
The second cavity surface of the first mold is formed integrally with the resin flow path,
The removing step includes a step of removing the protruding portion from the resin molded product together with the resin formed in the resin flow path.
The manufacturing method of the resin molded product of Claim 1. The transfer sheet has an opening,
The second mold has the resin flow path,
The first mold has a resin injection port for injecting resin into the resin flow path of the second mold,
The transfer sheet arranging step includes a step of arranging the opening of the transfer sheet at the resin injection port and a step of arranging another transfer sheet different from the transfer sheet in the second mold,
The molding step includes a step of injecting resin from the resin injection port of the first mold into the resin flow path of the second mold through the opening.
The manufacturing method of the resin molded product of Claim 2. The first mold is provided with the second cavity surface at four locations around the first cavity surface,
The transfer sheet arranging step includes a step of arranging a transfer sheet by aligning positions of both end portions of the transfer sheet on the four second cavity surfaces.
The manufacturing method of the resin molded product as described in any one of Claim 1 to 3. The projecting portion includes a first projecting portion and a second projecting portion formed by connecting two locations of the four second cavity surfaces, respectively.
The removing step includes a step of removing the first protruding portion and the second protruding portion from the resin molded product,
The manufacturing method of the resin molded product of Claim 4. An injection mold for performing molding of a resin molded product and transfer of a transfer layer from a transfer sheet to the resin molded product at the time of injection molding,
A first cavity surface on which the transfer sheet is partially disposed to form the resin molded product, and a second cavity surface connected to the first cavity surface to form a protrusion on the resin molded product. Having a first mold;
A second mold adapted to the first mold;
With
The mold for injection molding, wherein the first mold is provided with the second cavity surface at an arrangement position of an end portion of the transfer sheet crossing the first cavity surface. In the first mold, the second cavity surface is connected to the first cavity surface at the same depth as the first cavity surface.
The injection mold according to claim 6. At least one of the first mold and the second mold has a resin flow path for pouring resin into the first cavity surface,
The second cavity surface of the first mold is provided integrally with the resin flow path for pouring resin into the first cavity surface.
The injection mold according to claim 6 or 7. An injection mold for performing molding of a resin molded product and transfer of a transfer layer from a transfer sheet to the resin molded product at the time of injection molding,
A first mold having a parting surface and a first cavity surface on which the transfer sheet is partially disposed to form the resin molded product;
A second mold adapted to the first mold;
With
The mold for injection molding, wherein the parting surface of the first mold has an inclined portion that is inclined from an arrangement area where the transfer sheet is arranged to a non-arrangement area where the transfer sheet is not arranged. An injection mold for performing molding of a resin molded product and transfer of a transfer layer from a transfer sheet to the resin molded product at the time of injection molding,
A first mold having a first cavity surface on which the transfer sheet is partially disposed to form the resin molded product;
A second mold adapted to the first mold;
With
The first mold or the second mold has a resin flow path for pouring resin into the first cavity surface,
The first mold has a fitting structure for pressing the transfer sheet across the resin flow path at the boundary of the transfer sheet arrangement region,
The second mold has a fitted structure fitted to the fitting structure,
The resin flow path passes between the fitting portions of the fitting structure and the fitting structure and enters the arrangement area of the transfer sheet and changes the direction in the longitudinal direction of the transfer sheet in the arrangement area. An injection mold having a shape connected to the first cavity surface in the vicinity of the center of the arrangement region.

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