JP5183293B2 - Insert method in blow molding - Google Patents

Description

  The present invention relates to an insert method in blow molding in which a hollow insert product such as a duct, a tank, and a bottle is blow-molded and a cylindrical insert part is inserted during blow molding.

As a method of inserting a cylindrical insert part into a blow molded duct or the like, a mold in which a concave part for inserting a cylindrical insert part having openings at both ends is formed in a mold cavity is used. The insert part is inserted into the recess of the mold, and the parison that is expanded by the pressurized fluid is also expanded and integrated in the insert part. The method is disclosed in Japanese Patent No. 3285952, and a parison for inserting a mouth member provided with a partition wall for closing an opening into a recess formed in a cavity of a mold and inflating with a pressurized fluid, and a cavity side end portion of the mouth member Japanese Patent No. 3275102 discloses a method in which the two are welded and integrated in the mouth member without the parison bulging.
Japanese Patent No. 3285952 Japanese Patent No. 3275102

  In the insert method in blow molding described in the above-mentioned Patent Document 1, the wall portion bulging into the mouth member after the molding is cut off to open the mouth member. Since only the wall to be pressed is pressed, the stress due to it concentrates on the welded part between the end of the mouth member and the parison, and the mouth member may be peeled off, or the wall part to be cut off may cause stress during cutting. There is a problem that the opening to be cut has a rough surface because it does not have sufficient rigidity to be received.

  On the other hand, according to the insert method in blow molding described in Patent Document 2, the cavity side end of the mouth member is closed with a partition in advance, and insert molding is performed. Although no inconvenience occurs, the mouth member is pushed into the groove by the parison during molding and is not welded correctly. Therefore, in order to open the mouth member after molding, the double wall of the partition wall and the resin wall formed on the surface must be excised, and not only the excision processing is easy, but also the stress during excision does not increase. From this point, it has been found that the stress is also concentrated on the welded portion between the end portion of the mouth member and the parison and the effect of preventing the mouth member from peeling is not so much.

  The present invention addresses the above-described problems, and uses a mold in which a concave groove for inserting a cylindrical insert part is formed in a cavity as a mold for blow molding. Insert the cylindrical insert part into the concave groove of the mold cavity, hold it in a stationary state and blow-mold it, so that the parison that is expanded by the pressurized fluid pushes the insert member into the cavity and does not deform The part and the parison can be strongly welded, and the wall that closes the insert part is also formed in the welded part with the parison and its periphery is strengthened, so the insert part can be opened after molding The wall part that closes the insert part can be cut off reliably and accurately, especially the cylindrical insert part is a soft material Even if it is made of bellows or is flexible, it eliminates the deformation of the cylindrical insert parts due to the blow pressure during blow molding, welding defects and other problems, and the cylindrical insert after molding It is an object of the present invention to provide an insert method in blow molding which can accurately perform opening processing of parts.

In order to achieve the above object, the present invention provides the following method. That is, the insert method in blow molding according to claim 1 is a division in which a concave groove for inserting a cylindrical insert part made of a soft material or accordion-like and having flexibility is formed in a cavity. A cylindrical mold is used, and the cylindrical insert part is inserted into a concave groove of the cavity of the mold that is opened, and the cylindrical insert part is stretched around the outer periphery and the inner periphery of the cavity side end. An annular projection is formed, and the cylindrical insert part is inserted into the groove and held stationary in the cavity by contacting the inner and outer cavity surfaces of the groove. And placing a parison between the molds, then clamping the mold and introducing a pressurized fluid into the parison to expand the parison along the cavity, and The cavity side end of the insert part is welded and integrated, then the mold is opened and the molded product is taken out, and then the part closed by the parison of the insert part is cut out and opened. It is.

Further, the insert method in blow molding according to claim 2 is a division in which a concave groove is formed in a cavity for fitting a flexible cylindrical insert part made of a soft material or having a bellows shape and flexibility. A cylindrical mold is used, and the cylindrical insert part is inserted into a concave groove of the cavity of the mold that is opened, and the cylindrical insert part is an annular protrusion that protrudes to the outer periphery of the cavity side end. And the inner periphery is closed by a thin film, and an annular projection protruding to the outer periphery is brought into contact with the cavity surface on the outer periphery side of the groove, and the inner periphery side of the groove is closed by a thin film. The cylindrical insert part is inserted into the recessed groove and held stationary in the cavity so that the end closed by the mold becomes the cavity side, and then a parison is placed between the molds. After the mold is clamped, a pressurized fluid is introduced into the parison to expand the parison along the cavity, and the parison, the outer periphery of the cavity side end and the thin film are welded and integrated, and then the mold After the mold is opened and the molded product is taken out, the thin film and the portion closed by the parison are both cut out and opened .

Further, the insert method in blow molding of claim 3 uses a split mold in which a concave groove for fitting a cylindrical insert part having a bellows shape and flexibility is formed in a cavity. The cylindrical insert part is inserted into the concave groove of the mold cavity, and the cylindrical insert part is formed with an annular protrusion projecting to the outer periphery of the cavity side end. The cylindrical insert part is inserted into the concave groove by interposing a separate spacer between the bellows-shaped inner peripheral surface of the cylindrical insert part and the inner column portion of the concave groove of the mold. In addition, the mold is clamped and then the mold is clamped, and then a pressurized fluid is introduced into the parison to expand the parison along the cavity, and the parison and the insert The cavity side end of the product is welded and integrated, then the mold is opened and the molded product is taken out, and then the part closed by the parison of the insert part is cut open and the spacer is removed. It is a feature .

  According to the present invention, the parison which is expanded by the pressurized fluid can be strongly welded to the cavity side end portion of the insert part and the parison without expanding into the insert part, and the wall which closes the insert part Since it is formed in the welded part with the parison and its periphery is solid, the wall part that closes the insert part can be cut off reliably and accurately when opening the insert part after molding. Even if the cylindrical insert part is made of a soft material or has a bellows shape and is flexible, the cylindrical insert part may be deformed due to blow pressure at the time of blow molding, welding defects, and other problems. It is possible to obtain an effect of accurately performing opening processing of the cylindrical insert part after molding.

The drawings explain the insert method in blow molding according to the present invention by taking the blow molding aspect of the duct as an example. FIG. 1 is a sectional view showing the blow molding aspect of the duct, FIG. 2 is a front view of the same, and FIG. FIG. 4 is a partial perspective view of the duct, and FIG. FIG. 5 is a partial cross-sectional view of a duct showing an embodiment in which an annular protrusion is formed as a cylindrical insert part projecting to the outer periphery of the cavity side end, and FIG. 6 is a side view of the cavity as a cylindrical insert part. FIG. 7 is a partial cross-sectional view of a duct showing a form in which an annular protrusion projecting on the outer periphery of the end portion is formed and a separate spacer is interposed on the inner periphery, and FIG. 7 is a view of the duct shown in FIG. FIG . 8 is a cross-sectional view showing a blow molding mode, and FIG . 8 shows a mode in which a cylindrical insert part whose one end is closed by a thin film is inserted and blow-molded so that the closed end is on the cavity side of the mold. It is sectional drawing.

  As shown in FIGS. 1 and 2, in the split molds 1 and 2 for blow molding, one of the molds 1 has a concave groove 4 for fitting a cylindrical insert part 3 into a cavity. 5 is formed. 6 is a parison and 7 is an extrusion die. 3 and 4, 8 is a duct, and the insert part 3 is welded to the duct 8 at the time of blow molding.

In the blow molding of the duct 8, the mold open and the mold 1, 2 of one mold 1 of the groove 4, and held immobile state fitted a cylindrical insert part 3, between the mold 1 and 2 The parison 6 is placed in Next, after the molds 1 and 2 are clamped, a pressurized fluid is introduced into the parison 6 to expand the parison 6 along the cavity 5, and the parison 6 and the cavity-side end 9 of the insert part 3 are integrally welded. Make it.

  The cylindrical insert part 3 has a bellows shape. The end portion 9 on the cavity 5 side of the cylindrical insert part 3 is formed with annular protrusions 10 and 11 projecting to the outer periphery and the inner periphery thereof, and the cylindrical insert part 3 is formed into the concave groove 4 of the cavity 5. The annular protrusion 10 contacts with the cavity surface on the outer peripheral side of the concave groove 4 while the annular protrusion 11 contacts with the cavity surface on the inner peripheral side of the concave groove 4 in the state of being inserted into the cylindrical insert part 3. Is inserted into the groove 4 and held in the cavity 5 in a stationary state, and the open end of the groove 4 is closed by the annular protrusion 10 and the annular protrusion 11. At the end 9 on the cavity 5 side of the cylindrical insert part 3, a projection 12 is formed so as to protrude from the annular projections 10 and 11 in the distal direction.

  Therefore, when the parison 6 is expanded along the cavity 5 by the pressurized fluid in this manner, the expanding parison 6 surrounds the protrusions 10 and 11 and the protrusion 12 at the side end portion 9 of the cavity 5 of the cylindrical insert part 3. So as to be integrated. The end portion on the cavity 5 side of the cylindrical insert part 3 is closed by a wall formed by a parison 6. Reference numeral 13 denotes a closed wall portion. This closed wall portion 13 is cut out by post-processing as the entire cut portion a to open the cylindrical insert part 3 (see FIG. 3), thereby obtaining the duct 8 shown in FIG. The wall formed by the parison 6 that closes the cylindrical insert member 3 is stretched and thinned during expansion, and is formed in a welded portion with the parison 6 so that its periphery is strong. The closed wall portion 13 that closes the cylindrical insert member 3 can be reliably and accurately cut off when the cylindrical insert member 3 is opened after the molding.

  As shown in FIG. 1 and FIG. 2, the cylindrical insert part 3 is formed with annular protrusions 10 and 11 projecting on the outer periphery and inner periphery of the cavity side end 9. 5, the annular projection 14 projecting only on the outer periphery as shown in FIG. 5 or an annular projection projecting only on the inner periphery (not shown) may be formed. In the embodiment shown in FIG. 5, the protrusion 12 protruding in the distal direction is provided, and in the embodiment (not shown), the protrusion 12 protruding in the distal direction is provided.

  In the embodiment shown in FIG. 6, the inner periphery of the end portion on the side of the cavity 5 of the cylindrical insert part 3 in a state where the cylindrical insert part 3 having the form shown in FIG. 5 is fitted in the concave groove 4 of the cavity 5. A spacer (reinforcing ring) 15 is fitted on the side and blow-molded. By providing the spacer 15 in this manner, the strength of the welding and integration of the duct 8 and the insert part 3 is enhanced, which is particularly suitable for a high-pressure duct. The spacer 15 is removed after molding, but may be left as it is to maintain strength as shown in FIG.

  The duct 8 having the form shown in FIG. 6 is molded in the form shown in FIG. 7, but the spacer 15 is flush with the cavity 5, and the bellows-like inner peripheral surface of the cylindrical insert part 3 and the recess of the mold 1. Since the cylindrical insert part 3 inserted in the mold 1 is interposed between the inner support column part of the groove 4, the end portion 9 on the cavity 5 side is fixed to the cavity 5 of the mold 1 and blow-molded. Is done. For this reason, even if the cylindrical insert part 3 is made of a soft material or is accordion-like and has flexibility, the cylindrical insert part 3 is displaced or deformed by the blow pressure at the time of blow molding. , Welding failure and other problems do not occur. Note that the entire surface of the blocking wall portion 13 is cut out by post-processing as a cutting portion a.

  Further, as shown in FIG. 8, a cylindrical insert part 3 having a shape in which one end is closed by a thin film 16 is formed in advance, and the closed end part of the cylindrical insert part 3 is formed. According to the aspect of inserting and blow-molding so as to be on the cavity 5 side, the cylindrical insert part 3 is supported by the cavity 5 even in the thin film 16 portion, so that the concave groove 4 of the mold 1 is formed in the cavity 5. The side is closed by the annular protrusion 14 and the thin film 16. For this reason, a part of the parison 6 does not fall into the concave groove 4 of the mold 1 due to the blow pressure, and the insert accuracy of the insert part 3 can be improved. In particular, this effect is remarkable when the cylindrical insert part 3 is made of a soft material or is accordion-like and has flexibility. Note that the entire surface of the blocking wall portion 13 closed by the thin film 16 and the parison 6 after the blow molding is cut as a cut portion a, and the cylindrical insert part 3 is opened.

  According to the insert method in blow molding according to the present invention, since the annular protrusions 10, 11 or 14 are formed at the cavity 9 side end 9 of the cylindrical insert part 3, the cavity 5 of the cylindrical insert part 3 is formed. The side insert 9 is blow-molded in a state where it is securely supported by the cavity 5, and the cylindrical insert part 3 can be a soft one as well as a hard one. 3 and the parison 6 can be highly integrated.

  In the present invention, the soft material in the case where the insert part is formed by blow molding, injection molding, extrusion molding, pressure forming, etc., is a soft plastic or rubber having a flexural modulus of 1.0 to 700 MPa. -Thermoplastic elastomers or compositions containing them. If the flexural modulus is less than 1 MPa, even if the protrusion is supported by the mold, the insert part will be lost to the blow pressure and fall into the groove. In addition, if a bending elastic modulus exceeds 700 Mpa, it is not necessary to attach a protrusion and to support in a metal mold | die.

  In the present invention, it is preferable to use a resin of the same system as the material of the molded product by blow molding and the material of the insert component because the insert component is firmly welded to the molded product at the time of blow molding. For example, when a molded product by blow molding is formed of polyolefins such as polyethylene or polypropylene, the insert part is also an olefin-based soft material, and an ethylene-α-olefin-based soft plastic or rubber / thermoplastic elastomer. Or it forms using the composition which has them mainly.

  In addition, when a molded product by blow molding is formed of a polar polymer such as polyamide or ester, the insert part is also a polyamide-based or polyester-based soft material, and a polyamide-based or polyester-based soft plastic or rubber / heat It is formed using a plastic elastomer or a composition mainly composed of them.

  Similarly, in the case where the insert part has a bellows-like flexibility, it is preferable to use the same material for the bellows-like insert part and the blow-molded product.

It is sectional drawing which shows the blow molding aspect of the duct by the insert method in the blow molding which concerns on this invention. It is a front view same as the above. It is sectional drawing of the duct which gave the opening process after blow molding and was completed. It is a fragmentary perspective view same as the above. It is a fragmentary sectional view of the duct which shows the embodiment in which the annular projection projected on the perimeter of the cavity side end part is formed as a cylindrical insert part. FIG. 5 is a partial cross-sectional view of a duct showing a form in which an annular protrusion is formed on the outer periphery of the cavity side end portion as a cylindrical insert part and blow-molded with a separate spacer interposed on the inner periphery. It is sectional drawing which shows the blow molding aspect of the duct shown in FIG. It is sectional drawing which shows the aspect which inserts and inserts the cylindrical insert component which one end is closed with the thin film so that the closed end part may become the cavity side of a metal mold | die.

DESCRIPTION OF SYMBOLS 1, 2 Mold 3 Cylindrical insert part 4 Groove for fitting cylindrical insert part 5 Cavity 6 Parison 7 Extrusion die 8 Duct 9 Cavity side edge part of insert part 10, 11 Annular protrusion 12 Tip Protrusion protruding in the direction 13 Blocking wall portion 14 Ring-shaped protrusion 15 Reinforcement ring 16 Thin film a Cut portion

Claims (3)

The mold opened by using a split mold in which a concave groove for fitting a flexible cylindrical insert part made of a soft material or bellows is provided in a cavity. The cylindrical insert part is inserted into the concave groove of the cavity, and the cylindrical insert part is formed with annular protrusions projecting to the outer periphery and inner periphery of the cavity side end, By contacting the inner peripheral side and the outer peripheral side cavity surface, the cylindrical insert part is inserted into the concave groove and held in a stationary state in the cavity, and a parison is disposed between the molds, After the mold is clamped, a pressurized fluid is introduced into the parison to expand the parison along the cavity, and the parison and the end of the insert part on the cavity side are fused and integrated. In the insert method in the blow molding, characterized in that after the removal of the molded article by opening the mold by cutting a portion which is closed by the parison of the insert part is opened. The mold opened by using a split mold in which a concave groove for fitting a flexible cylindrical insert part made of a soft material or bellows is provided in a cavity. The cylindrical insert part is inserted into the concave groove of the cavity, and the cylindrical insert part is formed with an annular protrusion protruding on the outer periphery of the cavity side end, and the inner periphery is closed by a thin film. The ring-shaped projection protruding to the outer periphery is brought into contact with the cavity surface on the outer peripheral side of the groove, and the end closed by the thin film is closed by closing the inner peripheral side of the groove with the thin film. So that the cylindrical insert part is inserted into the groove and held in a stationary state in the cavity, and then a parison is placed between the molds, and the mold is clamped and then placed in the parison. Guides pressurized fluid Together inflate the parison along the cavity to the outer circumference and a thin film of the parison and the cavity end is integrally welded, then closed by the thin film and the parison after demolding by opening the mold An insert method in blow molding, characterized in that an open portion is cut together and opened. Using a split mold in which a concave groove for fitting a bellows-like cylindrical insert part having flexibility is formed in the cavity, the mold is opened in the concave groove of the mold cavity. The cylindrical insert part is fitted, and the cylindrical insert part is formed with an annular protrusion projecting to the outer periphery of the cavity side end , and the bellows-like inner peripheral surface of the cylindrical insert part The cylindrical insert part is inserted into the concave groove and held stationary in the cavity by interposing a separate spacer between the inner post portion of the concave groove of the mold and the After the mold is clamped, a pressurized fluid is introduced into the parison to expand the parison along the cavity, and the parison and the cavity side end of the insert part are welded and integrated, and then the mold Insert method in the blow molding, wherein a portion that is closed by the parison of the insert part after opening to demolding resected to remove the spacer together to open.

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