JP2017001306A - Core mold for blow molding and injection blow molding method using core mold for blow molding - Google Patents

Abstract

An object of the present invention is to uniformly inflate a parison while suppressing deviation of a gas ejected from a core mold during blow molding. A blow molding core mold for blow molding a parison has a plurality of disk-shaped members 20, and the disk-shaped members 20 are formed in a conical shape or a cylindrical shape by being connected in the axial direction. Each disk-shaped member 20 is provided with a supply passage 22 through which the compressed air (gas) flows in the axial direction radially inward, and the compressed air supplied on at least one side of the axial end surface. And a jetting surface 24 for jetting the gas outwardly in the radial direction. The jetting surface 24 communicates with the supply channel 22 and has a plurality of channels 28 formed radially toward the outer peripheral edge 26 and compressed air. It is formed in an annular shape so as to communicate with the flow path 28 adjacent between the spray section 30 and the flow path 28 and the spray section 30 that can be sprayed radially outward from the outer peripheral edge portion 26. And an annular communication passage 32. [Selection] Figure 3

Description

  The present invention relates to a core mold for blow molding and an injection blow molding method using a core mold for blow molding.

  Conventionally, the core mold of the injection blow molding method has a path through which gas is ejected outward from the core mold. A parison supported on the outer peripheral surface of the core mold is blow-molded by the ejected gas (for example, Patent Document 1).

JP 2008-254364 A

  However, although there is a desire to suppress the deviation of the gas ejected from the core mold at the time of blow molding to uniformly inflate the parison, there is a disclosure regarding the detailed structure of the core mold in the technology in Patent Document 1 above. No.

  The present invention was devised in view of the above points, and the problem to be solved by the present invention is to uniformly suppress the deviation of the gas ejected from the core mold at the time of blow molding, while maintaining a uniform parison. Is to inflate.

  In order to solve the above problems, the core mold for blow molding of the present invention takes the following means. First, the first invention is a blow molding core mold for blow molding a parison, wherein the core mold has a plurality of disk-shaped members, and the disk-shaped members are in the axial direction. Each of the disk-shaped members has a supply channel through which gas passes through in the axial direction radially inward, and at least one side of the axial end surface. An ejection surface that ejects the gas supplied in the radially outward direction, and the ejection surface communicates with the supply channel and has a plurality of channels radially formed toward an outer peripheral edge, and An injection part capable of injecting gas radially outward from the outer peripheral edge part, and annularly formed between the flow path and the injection part and in communication with the flow path adjacent in the circumferential direction An annular communication passage.

  According to the first invention, the core mold has a plurality of disk-shaped members. Further, the core type is formed in a conical shape or a cylindrical shape by the disk-like members being continuous in the axial direction. Each disk-shaped member has a supply flow path through which gas is circulated in the axial direction radially inward, and an ejection surface for ejecting the gas supplied at least on one side of the axial end surface radially outward. . Thereby, gas is ejected from the boundary of each disk-shaped member. Therefore, the deviation in the axial direction of the gas ejected from the core mold can be suppressed. By increasing or decreasing the number of disk-shaped members, it is possible to provide an ejection surface according to the shape of the product, so that the design freedom of the core type is improved. The ejection surface communicates with the supply channel, and includes a plurality of channels formed radially toward the outer peripheral edge, an injection unit capable of injecting gas radially outward from the outer peripheral edge, And an annular communication path formed in an annular shape so as to communicate with a flow path adjacent to the circumferential direction between the path and the injection unit. The gas supplied from the supply channel flows out uniformly to the outer peripheral side through the channel. And the gas which flowed into the annular communication path before the injection unit is configured to be injected from the injection unit after staying in the annular communication path. Therefore, the gas ejected from the core mold can suppress the deviation in the circumferential direction. From the above, the gas ejected from the core mold at the time of blow molding can suppress the deviation in both the axial direction and the circumferential direction and can uniformly inflate the parison.

  Next, 2nd invention is said 1st invention, Comprising: The surface between the said flow paths adjacent to the circumferential direction among the said ejection surfaces is a support surface which each said disk-shaped member contacts. The flow path, the annular communication path, and the injection part are formed by being cut out inward in the axial direction from the support surface, and the notch depth of the injection part is It is set smaller than the notch depth of a flow path and the said annular communicating path.

  According to the second aspect of the invention, the notch depth of the injection portion is set smaller than the notch depths of the flow path and the annular communication path. Therefore, the jet pressure of the gas injected from the injection unit can be increased.

  Next, in a third invention, the core mold in the first invention or the second invention is mounted in an injection mold, and a parison is formed between the core mold and the injection mold by injection molding. A parison molding step for molding, and blow-molding the parison by taking out from the injection mold and mounting the parison in a state where the parison is supported on the blow mold and ejecting gas from the core mold A blow molding step.

  According to the third invention, a suitable injection blow molding method can be obtained by using the core mold of the above aspect.

  In the present invention, by taking the measures of the above-mentioned inventions, the parison can be uniformly inflated while suppressing the deviation of the gas ejected from the core mold at the time of blow molding.

It is sectional drawing of the core type for blow molding of this embodiment. It is the II-II arrow directional view of FIG. It is a perspective view of the disk-shaped member comprised by the core type | mold for blow molding of this embodiment. It is the IV-IV sectional view taken on the line of FIG. It is sectional drawing which showed the state which mounted | wore the injection mold with the core type | mold as a parison molding process of this embodiment. It is sectional drawing which showed the state with which the synthetic resin fuse | melted as a parison molding process of this embodiment is filled in an injection mold. It is sectional drawing which showed the state taken out from the injection mold in the state which supported the parison with the core type | mold. It is sectional drawing which showed the state mounted | worn in a blow molding die in the state which supported the parison with the core type | mold. It is sectional drawing which showed the state which supplies compressed air to a core type | mold and is blow-molded. It is sectional drawing which showed the state which removes a resin molded product from blow molding and a core type | mold, and removes an unnecessary part.

  Embodiments of an injection blow molding method using a blow mold core and a blow mold core according to the present invention will be described below with reference to the drawings. In this embodiment, a constant velocity joint boot that covers a constant velocity joint manufactured by an injection blow molding method will be described as an example.

  As shown in FIG. 10, the constant velocity joint boot 1 (hereinafter referred to as “boot 1”) is formed of a thermoplastic synthetic resin. The boot 1 is formed in a cylindrical shape having both ends opened. One end of the boot 1 has a small-diameter annular portion 5 having a relatively small diameter. The other end of the boot 1 has a large-diameter annular portion 6 that is larger in diameter than the small-diameter annular portion 5. An intermediate portion between the small-diameter annular portion 5 and the large-diameter annular portion 6 has a hollow bellows portion 2 in which ridge portions 3 and valley portions 4 are alternately adjacent. The boot 1 is formed by an injection blow molding method. The injection blow molding method includes a parison molding process by injection molding and a blow molding process. Detailed description of each step will be described later. In the injection blow molding method in the present embodiment, a core mold 10 shown in FIG. 1 is used.

  As shown in FIG. 1, the core mold 10 has an upper end mold 12, a plurality of disk-shaped members 20, and a lower end mold 14 stacked in order from the top to the bottom. The upper end mold 12, the plurality of disk-shaped members 20, and the lower end mold 14 are held in the axial direction with bolts 11 inserted therein. The upper end mold 12, the plurality of disk-shaped members 20, and the lower end mold 14 are made of steel. The upper end mold 12 is formed to have substantially the same diameter as the small diameter annular portion 5 of the boot 1. A screw hole 13 into which the bolt 11 is screwed is formed on the lower surface of the upper end mold 12. An introduction path 15 for introducing compressed air G (gas) (see FIG. 9) is formed inside the lower end mold 14. On the upper surface of the upper end mold 12, a supply path 16 having the same diameter as that of a supply flow path 22 of the disk-shaped member 20 described later is provided in addition to the introduction path 15. A bolt hole 17 into which the bolt 11 is inserted is provided on the lower surface of the upper end mold 12. The bolt hole 17 communicates with the supply path 16. The diameter of the bolt 11 is smaller than the inner diameter of the supply flow path 22 described later.

  As shown in FIGS. 1 to 3, the core mold 10 includes a plurality of disk-shaped members 20 made of steel plates, and is formed in a columnar shape by continuing in the axial direction. Depending on the shape of the product to be molded, the core mold 10 may have a conical shape. The outer diameter of the disk-shaped member 20 is smaller than the inner diameter of the bellows portion 2 (see FIG. 10) of the boot 1. Various thickness shapes are set as the thickness of the disk-shaped member 20 according to the shape of the product. The compressed air G supplied to the core mold 10 is configured to be ejected radially outward from the mating surface (boundary) of each disk-shaped member 20. Therefore, the thickness of the disk-shaped member 20 in the present embodiment is a thickness corresponding to the peak 3 because the bellows 2 is alternately adjacent to the peaks 3 (see FIG. 10) and the valleys 4 (see FIG. 10). It is good also as thickness corresponding to each of peak part 3 and trough part 4. Each disk-shaped member 20 includes a supply flow path 22 and an ejection surface 24.

  The supply flow path 22 is penetrated in the axial direction at the center of the disk-shaped member 20. The supply flow path 22 of each disk-shaped member 20 is penetrated with the same diameter, becomes a cylindrical shape by connecting in the axial direction, and becomes a passage for the compressed air G.

  The ejection surface 24 is provided on at least one side of the end surface in the axial direction of the disk-shaped member 20. In the present embodiment, the ejection surface 24 is provided on the upper surface side of the disk-shaped member 20, and a smooth surface is formed on the lower surface side. In addition, you may provide the ejection surface 24 on both upper and lower sides. The ejection surface 24 is a surface that ejects the compressed air G supplied from the supply passage 22 outward in the radial direction. The ejection surface 24 includes a plurality of flow paths 28, a support surface 34, an injection unit 30, and an annular communication path 32.

  The plurality of flow paths 28 communicate with the supply flow path 22 and are formed radially toward the outer peripheral edge 26. A surface between the circumferentially adjacent flow paths 28 is configured as a support surface 34. The support surface 34 is a surface that contacts and supports the lower surface of each disk-shaped member 20. A pin hole 36 penetrating in the axial direction is formed in a part of the support surface 34. A lock pin (not shown) is inserted into the pin hole 36. Thereby, the radial shift of each disk-shaped member 20 is prevented. The injection unit 30 is a part capable of injecting the compressed air G from the outer peripheral edge portion 26 outward in the radial direction. The injection unit 30 is an annular surface that is adjacent radially inward from the outer peripheral edge 26 of the disk-shaped member 20. The annular communication path 32 is formed in an annular shape so as to communicate with the flow path 28 adjacent in the circumferential direction between the flow path 28 and the injection unit 30. In the case where the ejection surface 24 is also provided on the lower surface side of the disk-shaped member 20, the plurality of flow paths 28 on the lower surface side and the plurality of flow paths 28 on the upper surface side may be provided with a phase shift. Good. Thereby, compressed air can be more uniformly injected toward an outer periphery.

  As shown in FIGS. 3 and 4, the flow path 28, the annular communication path 32, and the injection unit 30 are formed in a groove shape that is cut out inward in the axial direction from the support surface 34. The notch depth 30H of the injection unit 30 is set to be smaller than the notch depth 28H of the flow path 28 and the notch depth 32H of the annular communication path 32. Here, the notch depth 30H of the injection unit 30 is preferably in the range of 0.01 mm to 0.05 mm. If the cutout depth 30H is smaller than 0.01 mm, the compressed air G may not be injected. On the other hand, if the notch depth 30H is larger than 0.05 mm, the molten resin may enter the injection portion 30 and cause clogging in the injection molding in the parison process. The notch depth 28H of the flow path 28 and the notch depth 32H of the annular communication path 32 are preferably in the range of 0.1 mm to 0.5 mm. If the notch depth 28H of the flow path 28 and the notch depth 32H of the annular communication path 32 are smaller than 0.1 mm, the compressed air G may not flow from the supply flow path 22. On the other hand, if the notch depth 30H is larger than 0.05 mm, there is a possibility that a desired ejection pressure cannot be obtained in the compressed air G ejected from the ejection unit 30. The notch depth 28H of the flow path 28 and the notch depth 32H of the annular communication path 32 may not be the same depth. Further, the notch depths 30H, 28H, and 32H in each disk-shaped member 20 may be different from each other at positions close to and far from the introduction path 15 (in the axial direction of the core mold 10). This is suitable when a pressure difference occurs in the axial direction by changing the notch depth.

  Next, the injection blow molding method will be described with reference to FIGS. The injection blow molding method includes a parison molding process by injection molding and a blow molding process.

  As shown in FIGS. 5 and 6, the core mold 10 and the injection mold 50 are used in the parison molding process. The injection mold 50 is a split mold that divides in the radial direction. The inner surface of the injection mold 50 is a smooth surface. The core mold 10 is mounted in the injection mold 50. A space surrounded by the core mold 10 and the injection mold 50 is a cavity 52 for forming the parison P. A molten thermoplastic synthetic resin is injected into the cavity 52. On the outer peripheral surface of the core mold 10, the filled synthetic resin is stuck in a softened state to form a parison P. The parison P supported on the outer peripheral surface of the core mold 10 by injection molding has a smaller diameter than the constant velocity joint boot 1 as a whole.

  Next, the core mold 10 and the blow mold 60 are used in the blow molding process as shown in FIG. The blow mold 60 is formed with a concave portion 62 for forming the peak portion 3 in the bellows portion 2 of the boot 1 and a convex portion 64 for forming the valley portion 4. The blow mold 60 is a split mold that divides in the radial direction. As shown in FIG. 7, the injection mold 50 is divided from the radial direction and taken out with the parison P supported by the core mold 10. Then, as shown in FIG. 8, the core mold 10 supporting the parison P is mounted in the blow mold 60. As shown in FIG. 9, compressed air G is introduced from the introduction path 15 of the core mold 10. The compressed air G is supplied to the supply flow path 22 of the disk-shaped member 20 through the supply path 16 of the lower end mold 14. The compressed air G in the supply supply path 22 spreads radially outward through the plurality of flow paths 28. The compressed air G that has reached the annular communication path 32 stays in the annular communication path 32 and is then injected from the injection unit 30 toward the outer peripheral edge 26 and blow-molded. The compressed air G injected to the outside of the core mold 10 causes the parison P to bulge out and press against the concave portion 62 and the convex portion 64 to form the peak portion 3 and the valley portion 4. As shown in FIG. 10, the synthetic resin is cooled after blow molding. The core mold 10 and the synthetic resin are taken out from the blow mold 60. Unnecessary portions at both ends of the molded synthetic resin are removed to complete the boot 1 (FIG. 10).

  Thus, the core mold 10 for blow molding of the first embodiment has a plurality of disk-shaped members 20. Moreover, the core type | mold 10 is formed in the cone shape or the column shape by the disk-shaped member 20 continuing in an axial direction. Each disk-shaped member 20 has a supply flow path 22 through which compressed air G (gas) flows in the radial direction inward in the radial direction, and compressed air G supplied on at least one side of the axial end surface. And an ejection surface 24 that ejects outward in the direction. Thereby, the compressed air G is ejected from the boundary of each disk-shaped member 20. Therefore, it is possible to suppress the deviation in the axial direction of the compressed air G ejected from the core mold 10. By increasing / decreasing the number of the disk-shaped members 20, the ejection surface 24 according to the shape of the product can be provided, so that the design freedom of the core mold 10 is improved. In addition, the ejection surface 24 communicates with the supply flow path 22 and injects a plurality of flow paths 28 formed radially toward the outer peripheral edge 26 and the compressed air G outwardly in the radial direction from the outer peripheral edge 26. It has a possible injection section 30, and an annular communication path 32 formed in an annular shape so as to communicate with the flow path 28 adjacent to the circumferential direction between the flow path 28 and the injection section 30. The compressed air G supplied from the supply flow path 22 flows out uniformly to the outer peripheral side through the flow path 28. The compressed air G that has flowed into the annular communication passage 32 in front of the injection unit 30 stays in the annular communication passage 32 and is then injected from the injection unit 30. Therefore, the compressed air G ejected from the core mold 10 can suppress the deviation in the circumferential direction. From the above, the compressed air G ejected from the core mold 10 at the time of blow molding can suppress the deviation in both the axial direction and the circumferential direction and can uniformly inflate the parison P.

  Further, the notch depth 30H of the injection unit 30 is set to be smaller than the notch depth 28H of the flow path 28 and the notch depth 32H of the annular communication path 32. Therefore, the jet pressure of the gas injected from the injection unit 30 can be increased.

  Moreover, a suitable injection blow molding method can be obtained by using the core mold 10 for blow molding of the said aspect.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment, It can implement in other various embodiment. For example, although the constant velocity joint boot has been described in the present embodiment, the present invention is not limited to this and can be applied to a bellows such as an expansion tube having a bellows structure.

DESCRIPTION OF SYMBOLS 1 Constant velocity joint boot 2 Bellows part 3 Mountain part 4 Valley part 5 Small-diameter annular part 6 Large-diameter annular part 10 Core type 11 Bolt 12 Upper end type 13 Screw hole 14 Lower end type 15 Introduction path 16 Supply path 17 Bolt hole 20 Disc shape Member 22 Supply channel 24 Ejection surface 26 Outer peripheral edge 28 Channel 28H Channel cutout depth 30 Injection unit 30H Injection unit cutout depth 32 Annular communication passage 32H Annular communication passage notch depth 34 Support surface 36 Pin hole 50 Injection mold 52 Cavity 60 Blow mold 62 Recess 64 Projection G Compressed air (gas)
P Parison

Claims (3)

A blow mold core for blow molding a parison,
The core type is
It has a plurality of disk-shaped members, and the disk-shaped members are formed in a conical shape or a cylindrical shape by being continuous in the axial direction,
Each of the disk-shaped members includes
A supply flow path through which gas passes through in the axial direction radially inward;
An ejection surface for ejecting the gas supplied on at least one side of the axial end surface radially outward,
The ejection surface is
A plurality of channels formed in a radial pattern toward the outer peripheral edge in communication with the supply channel;
An injection part capable of injecting the gas from the outer peripheral edge part radially outward;
A core mold for blow molding, comprising: an annular communication passage formed in an annular shape so as to communicate with the flow passage adjacent in the circumferential direction between the flow passage and the injection section. A core mold for blow molding according to claim 1,
Of the ejection surfaces, the surface between the flow paths adjacent in the circumferential direction is provided as a support surface in contact with each of the disk-shaped members,
The flow path, the annular communication path, and the injection portion are formed by being cut out inward in the axial direction from the support surface,
A blow mold core mold in which a notch depth of the injection portion is set to be smaller than a notch depth of the flow path and the annular communication path. A parison molding step of mounting the core mold according to claim 1 or 2 in an injection mold and molding a parison between the core mold and the injection mold by injection molding,
A blow molding step of taking out the parison by ejecting gas from the core mold while being taken out from the injection mold and mounted on the blow mold in a state where the parison is supported by the core mold. Injection blow molding method.

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