JP2014133394A - Injection molding die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding die which is used for molding a molded article so that a gate mark is positioned at the edge of a thin wall part of the molded article and at the edge thereof on the non-exterior surface side.SOLUTION: An injection molding die 1 includes an upper die 11, a lower die 12, and lower split dies 12a, 12b so that a cavity 2 is formed by these dies. The lower die 12 is used for forming a gate 13. A gate mouth G is opened to the cavity 2 and to a slope 20 formed by chamfering two surfaces 2a, 2b on the lowermost end side of the cavity 2. The two surfaces 2a, 2b are made respectively to face two faces connected to the edge of the thin wall part of the molded article on the non-exterior surface side. As a result, a thin-wall molded article, in which a concave part for the conventional countermeasure against gate marks cannot be formed, can be molded so that the thin-wall molded article is combined with another component without causing interference and the gate mark (a convex shape) is not exposed to the exterior surface.

Description

  The present invention relates to an injection mold for forming a molded product having a thin portion.

  Conventionally, in injection molding in which a required amount of a molding resin material is flowed into a closed mold (called a cavity) through a nozzle called a gate, the resin of the gate part after molding is separated and its shear mark ( Various studies have been made on the processing of gate traces. This is to meet the demand for simplifying the work of separating the unnecessary resin from the gate portion and the demand for hiding or making the gate trace inconspicuous from the necessity of design or functionality. The gate mark is generated at a position of an injection hole (called a gate port) which is a communication portion between the cavity and the gate. Therefore, for example, the position and structure of the gate opening is designed so as to hide the gate mark in the concave portion intentionally provided on the product surface. Thereby, it is possible to prevent protruding gate marks from protruding from the product surface of the molded product.

  In addition, in the injection molding method of the sealing material for the scroll compressor, there is no need to separate the resin of the gate part by a separate operation, and there is a manufacturing method that prevents the gate mark from being generated on the side surface or the end surface that is the sealing surface It is known (see, for example, Patent Document 1). In this manufacturing method, a gate for injecting a resin material into a cavity of a molding die is formed in a banana shape, and a gate opening is provided on a surface of the cavity that does not adversely affect sealing performance. To form a sealing material. In this gate structure and manufacturing method, the resin solidified in the gate is moved and removed along the curve shape of the banana outline by the ejector pin after molding, and it is automatically cut from the product part during the movement. Therefore, a separate cutting operation is unnecessary. Moreover, even if the gate mark remains, there is no possibility of adversely affecting the product functions such as sealing performance from the position.

JP 2000-45968 A

  However, in the conventional gate structure in which the gate trace is hidden in the concave portion as described above, or the gate trace is located in a place where the product function is not affected as shown in Patent Document 1, the thin wall portion of the product is used. The gate opening cannot be provided. For example, the concave portion provided in the gate portion so that the convex shape of the gate trace does not protrude from the product surface can be installed only when a sufficient area is secured. However, when it is necessary to provide a gate opening on the end face of the thin wall edge, it is impossible to form a recess that hides the gate trace on the narrow end face, and the gate is located away from the edge due to the mold design. It may be difficult to provide a mouth.

  The present invention solves the above-described problems, and is formed with a simple configuration so that the gate mark is located at the edge of the thin-walled portion of the molded product and at the edge on the non-appearance surface side. An object of the present invention is to provide an injection mold that can be used.

  In order to achieve the above object, an injection mold of the present invention comprises a cavity for filling a molding resin and molding a molded product having a thin wall portion, and a gate for injecting the molding resin into the cavity from a gate port. In addition, in the injection mold, the cavity is a chamfer so that the portion facing the edge on the non-appearance surface side is an inclined surface with respect to the two surfaces connected to the edge. The gate opening is open to the slope.

  In this injection mold, it is preferable that the gate has an arcuate cross-sectional axis and a shape in which the cross-sectional area decreases toward the gate opening.

  According to the injection mold of the present invention, the cavity is a thin part of the molded product, and has a slope on the part facing the edge on the non-appearance surface side, and the gate opening is opened on the slope. The gate mark can be positioned at the edge of the thin part of the molded product that is on the non-appearance surface side.

Sectional drawing which shows the gate part of the injection mold which concerns on one Embodiment of this invention. Sectional drawing which shows arrangement | positioning of the same gate part with respect to the whole same injection mold in the state except one part split mold. (A) is a perspective view which shows the molded article shape | molded with the injection mold, (b) is an enlarged perspective view of A part of (a). The perspective view which shows resin of the molded product part and gate part which were solidified within the same injection mold. The perspective view which looked at the resin of the molded product part shown in FIG. 4 and the gate part from another viewpoint. (A) is sectional drawing which shows the gate part of the injection mold which concerns on other embodiment, and the solidified resin of the inside, (b) is a cross section which shows a mode that the injection mold is opened and resin in a gate is extracted Figure.

  Hereinafter, an injection mold according to an embodiment of the present invention will be described with reference to the drawings. 1 and 2 show an injection mold according to one embodiment, and FIGS. 3, 4 and 5 show a molded product molded by the injection mold. As shown in FIGS. 1 and 2, the injection mold 1 includes an upper mold 11, a lower mold 12, and lower divided molds 12 a and 12 b, and these molds define a cavity 2 that is a space into which resin flows. Form. FIG. 2 shows a state in which the lower split mold 12b is removed. The lower mold 12 forms a gate 13, the lower divided mold 12 a forms a runner 15, and the lower mold 12, the lower divided mold 12 a, and the upper mold 11 form a runner 14. In the cavity 2, a gate port G of a gate 13 formed in the lower mold 12 is opened. The runner 15, the runner 14, the gate 13, and the gate port G communicate with each other in this order to provide a path for supplying the resin for injection molding to the cavity 2. The gate port G opens to a slope 20 formed by chamfering the two surfaces 2 a and 2 b on the lowermost end side of the cavity 2. The injection mold 1 is, for example, a mold formed by cutting a metal material, and the molding material is, for example, a thermoplastic resin.

  A molded product 3 by the injection mold 1 is, for example, a frame-type decorative frame for a wall-embedded outlet, and as shown in FIGS. 3A and 3B, a cover portion 31 having a window portion, and a cover portion 31. And a side wall portion 32 rising from the side wall. A slope 4 is chamfered on the end face 33 of the edge of the side wall 32, and a gate mark 41 is formed on the slope 4. As shown in FIGS. 4 and 5, the gate mark 41 is solidified by the gate 13 and runner 14 of the injection mold 1 to become the gate resin 13p and runner resin 14p, and the gate resin 13p is molded. This is a shear mark when the product 3 is sheared and separated.

  The molded product 3 serving as the frame decorative frame is a thin molded product having an overall thickness of, for example, approximately 2 mm. The end surface 33 of the side wall portion 32 is a hidden surface that is not an appearance surface when the molded product 3 is used, that is, a non-appearance surface, but the end surface 33 is a surface that requires flatness and protrudes from the end surface 33. This is a surface that does not allow the presence of gate marks. However, the method of providing a concave portion and sinking the gate mark in the concave portion as conventionally taken as a measure for the gate mark cannot be applied to the end face 33 of such a thin portion. Moreover, even if the inner surface side of the molded product 3 is not the appearance surface, it is necessary to avoid providing a gate port at a position on the inner surface side from the viewpoint of the design and manufacture and operation of the mold.

  Therefore, the cavity 2 of the injection mold 1 includes the inclined surface 20 chamfered with respect to the two surfaces 2 a and 2 b as described above, and the gate port G is open to the inclined surface 20. The surfaces 2a and 2b of the cavity 2 are thin-walled portions of the molded product 3 and are opposed to two surfaces connected to the edge portion on the non-appearance surface side, that is, the surfaces of the end surface 33 and the side wall portion 32, respectively. It is a surface to do. Further, the inclined surface 20 of the cavity 2 is a surface facing the inclined surface 4 of the molded product 3. Here, the facing surfaces are based on the positional relationship between the outer surface of the molded product 3 and the inner wall surface of the cavity 2 facing each other when the molded product 3 is in the cavity 2 during molding. It is a surface. Thus, in order to provide the gate port G close to the position to be the end surface 33 of the thin portion, the inclined surface 4 is formed on the end surface 33 of the molded product 3, and the gate port G is formed at the position to be the inclined surface 4 during molding. The gate 13 is configured to be positioned.

  According to this injection mold 1, the gate port G is provided with the inclined surface 20 on the inner wall portion of the cavity 2, the thin portion of the molded product 3, and the portion facing the edge on the non-external surface side. Since the opening is opened, the gate mark 41 can be arranged on the edge of the thin portion of the molded product 3 on the non-appearance surface side. Therefore, according to the injection mold 1, there is no interference when assembling with other parts, as in the conventional case, even in a thin molded product in which a conventional recess for preventing gate traces cannot be formed. ) Does not appear on the exterior surface and can be molded so as not to affect the exterior surface. In the embodiment, a slope is formed with respect to the end face 33 having a thickness of about 2 mm, and a die having a gate structure with a gate opening G of φ0.9 mm is used as shown in FIGS. As shown, a molded product satisfying the requirements in appearance and functional dimensions was obtained.

  6 (a) and 6 (b) show an injection mold 1 according to another embodiment. The gate 13 of the injection mold 1 has a curved gate structure, the cross-sectional axis is an arc shape, and the cross-sectional area becomes smaller toward the gate port G. Therefore, as shown by the arrow B, the gate resin 13p solidified in the gate 13 can be extracted from the gate 13 while being swung without being deformed. According to the injection mold 1 having such a gate structure, the removal operation of the gate resin 13p is facilitated in molding with a hard-to-deform molding resin in a solidified state, and the production efficiency of injection molding can be improved.

  The present invention is not limited to the above-described configuration, and various modifications can be made. For example, the injection mold 1 may be formed of any material other than a metal material. Further, the molding material is not limited to the thermoplastic resin, and any injection molding material can be used. In addition to the molding material that is hard to deform in the solidified state, easily deformable material such as rubber can be used. .

DESCRIPTION OF SYMBOLS 1 Injection mold 13 Gate 2 Cavity 2a, 2b surface 20 Slope 3 Molded product 33 End surface G Gate port

Claims (2)

In an injection mold comprising a cavity for filling a molding resin and molding a molded product having a thin portion, and a gate for injecting the molding resin into the cavity from a gate port,
The cavity is chamfered so that a portion facing the edge that is a thin-walled portion of the molded product and a non-appearance surface is an inclined surface with respect to two surfaces that are continuous with the edge,
An injection mold characterized in that the gate port is open to the slope.   2. The injection mold according to claim 1, wherein the gate has an arcuate cross-sectional axis and a shape in which a cross-sectional area decreases toward the gate opening. 3.

Images