JPH0356528B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to improvements in blow molding equipment and blow molding methods.

[Prior art] Methods for molding hollow products with a wide neck at one end and precision in shape and size include injection blow molding and expanding the large diameter end of the parison to create large and small diameter products. There is a method of blow molding by inserting a mandrel that forms the inner shape.

[Problems to be Solved by the Invention] Injection blow molding requires an injection mechanism, a parison mold, a plurality of cores, and a mechanism for transporting the core, resulting in a complex mechanism and high cost.
In the method of enlarging the end of the parison, the enlarging mechanism and the mandrel insertion mechanism are separate, which complicates the apparatus. Further, since the enlarged portion is tapered, the stretching conditions of the parison during blow molding are different, and there is a problem that the parison is significantly deformed during enlargement and the thickness becomes non-uniform.

The present invention provides a blow molding device (first invention) that has a simple mechanism and prevents deformation and non-uniform thickness of the parison, and a blow molding device (first invention) that has a simple mechanism to prevent parisons from becoming deformed and non-uniform in thickness. It is an object of the present invention to provide a blow molding method (second invention) for manufacturing a product.

[Means for Solving the Problems] The blow molding apparatus of the first invention will be described with reference to a typical example shown in FIG. A mold 1 that is freely divided into two or more parts, a distal end portion 21 having a parison expansion member 22 that can be inserted into the inside of the parison 4 before expansion and can be expanded and contracted in the radial direction, and a tip section 21 that has a parison expansion member 22 that is larger than the inner diameter of the parison 4 before expansion. a rear end portion 23 having a neck molding member 24 forming the inner surface of the neck portion, and a mandrel 2 having a gas introduction hole (not shown) for introducing gas into the parison 4; through the parison enlargement member 2
2 and an expansion/contraction mechanism 3 for expanding/contracting the image.

The blow molding method of the second invention is shown in FIGS.
To explain using a representative example shown in the figure, a first step of extrusion molding the parison 4, and a distal end portion having a parison expansion member 22 that can be inserted into the inside of the parison 4 and can be expanded and contracted in the radial direction as shown in FIG. 21, and a rear end portion 23 having a neck molding member 24 forming an inner surface of the neck portion larger than the inner diameter of the parison 4 before expansion, and a gas introduction hole (for introducing gas into the parison 4). The tip 21 of the mandrel 2 has a
is inserted into the inside of the parison 4, and as shown in FIG. 2, the parison expansion member 22 is expanded in the radial direction to expand the parison 4 in the radial direction, and the parison expansion member is contracted. and a third step of further inserting the mandrel 2 into the enlarged parison 4 as shown in FIG. 3, and inserting the neck molding member 24 of the mandrel 2 into the parison 4; A fourth step of closing the mold 1 divided into two or more parts and holding the parison 4 in its cavity, and releasing the parison 4 from the gas introduction hole of the mandrel 2.
It is characterized by comprising a fifth step of introducing gas into the mold and molding the parison 4 along the mold surface of the mold 1.

The mold, which is a component of the blow molding apparatus of the first invention and used in the blow molding method of the second invention, has a cavity shape that corresponds to the outer shape of the hollow product and has a wide neck at one end.
It is divided into the above parts, and its shape and material are not particularly limited, and commonly used ones can be used.

The mandrel, which is a component of the blow molding apparatus of the first invention and is used in the blow molding method of the second invention, is composed of a front end portion having the above-mentioned parison expanding member and a rear end portion having the above neck forming member. It has a gas introduction hole for introducing gas into the parison. The parison expansion member is not particularly limited as long as it can be inserted into the parison before expansion and can expand and contract in the radial direction.

As shown in FIGS. 1 and 2, the parison enlarging members are a set of at least three disposed in the circumferential direction of the tip 21 of the mandrel 2, one end of which is pivoted to the tip 21, and the other. An opening/closing arm 22A whose end opens and closes in the radial direction, and one end of which opens and closes the opening/closing arm 22A, one end of which is pivoted to the opening/closing arm 22A and the other end of which is pivoted to the mandrel 2 so as to be movable in the axial direction of the mandrel 2. The connecting portion 22B may be configured as a connecting portion 22B. Therefore, in the parison expanding step of the second step of the blow molding method of the second invention, the mandrel 2
The parison 4 is enlarged by driving the connecting part 22B in the axial direction of the mandrel 2 to open the opening/closing arm 22A, which has one end pivoted to the tip 21 of the mandrel 2 and whose other end opens and closes in the radial direction. be able to.

Furthermore, as shown in FIG. 1, the parison enlarging member is supported by a pressing hand 22 which is pivotally supported at the tip of the opening/closing arm 22A and which contacts the inner surface of the parison 4 and presses it in the radial direction.
C. Therefore, the parison expanding step of the second step of the blow molding method of the second invention is as follows:
The pressing hand 22C is pivotally supported at the tip of the opening/closing arm 22A.
The parison 4 can be expanded by pressing in the radial direction. In this case, the parison can be expanded in a particularly wide range and can be expanded into a shape close to the product shape, so that the stretching conditions for the parison can be made uniform.

Further, the parison expanding member can be an expandable bag such as a rubber bag. Further, the parison enlarging member may be a rack and pinion gear.

The expansion/contraction mechanism, which is a component of the blow molding apparatus of the first invention and used in the blow molding method of the second invention, is for expanding/contracting the parison expansion member through the mandrel. The expansion/contraction mechanism may be a cylinder device 31 composed of a piston and a cylinder, as shown in FIG. Then, the tip of the piston is pivotally supported on the connecting portion 22B. Therefore, the parison expanding/contracting step of the blow molding method of the second invention can be performed by using the cylinder device, expanding and contracting the piston, driving the connecting portion 21B in the axial direction of the mandrel 2, and opening and closing the opening/closing arm 22A. .

When the parison expansion member is an expandable bag such as a rubber bag, the expansion mechanism may be a fluid pump that pumps fluid into and out of the bag. Therefore, when the expansion/contraction mechanism is the fluid pump, in the parison expansion/contraction step of the blow molding method of the second invention, the parison can be expanded/contracted by causing fluid to enter and exit the bag.

Further, according to the method of the second invention, a mandrel is inserted into the parison expanded by the expansion/contraction mechanism, a neck molding member of the mandrel is inserted into the parison (the third step), and then a 2
The mold thus divided is closed to hold the parison in its cavity (fourth step). The neck shaping member of the mandrel then forms the inner shape of the wide neck of the hollow product. Also, the parison expansion member is contracted after expanding the parison.

Furthermore, gas is introduced into the parison through the gas introduction hole of the mandrel, and the parison is molded along the mold surface of the mold (fifth step). Thereafter, the hollow product of the desired shape is cooled, the mold is opened, and the mandrel is then pulled out to remove the desired hollow product.

According to the present apparatus and method, it is possible to manufacture a hollow product having a wide neck at one end and a narrow neck at the other end, as shown in FIG. can also produce closed hollow products.

[Example] The present invention will be explained below with reference to Examples.

Examples Since the method and apparatus of the present invention belong to the same technology, unless otherwise specified, the present invention will be collectively referred to as the present invention, and will be explained using examples.

A schematic sectional view of the blow molding apparatus of the present invention is shown in FIG. This device can be inserted into a mold 1 which is divided into two parts and which can be opened and closed and has a cavity shape according to the external shape of a hollow product, which has a wide neck at one end and a narrow neck at the other end, and a parison 4 before expansion. The distal end portion 21 has a parison expanding member 22 that can be expanded and contracted in the radial direction, and the rear end portion 23 has a neck forming member 24 that forms an inner surface of the neck portion that is larger than the inner diameter of the parison 4 before expansion. Gas introduction hole (not shown) for introducing gas into the parison 4
The parison enlarging member 22 is made up of a mandrel 2 and an expanding/contracting mechanism 3 for expanding/contracting the parison expanding member 22 through the mandrel. The parison expanding member 2
2 has an opening/closing arm 22A having one end pivoted to the tip and the other end opening/closing in the radial direction, and one end pivoting to the opening/closing arm 22A and the other end pivoted to the mandrel 2 so as to be movable in the axial direction of the mandrel 2. It consists of a connecting part 22B that opens and closes the opening/closing arm 22A, and a pressing hand 22C that is pivotally supported at the tip of the opening/closing arm 22A and comes into contact with the inner surface of the parison and presses it in the radial direction. Further, the expansion/contraction mechanism 3 is a cylinder device 3 composed of a piston and a cylinder.
It is 1. The tip of the piston is pivotally supported by the connecting portion 22B.

As shown in FIG. 1, the tip 21 of the mandrel was inserted into the extruded parison 4. Thereafter, the connecting portion 22 is
B was driven in the axial direction of the mandrel to open the opening/closing arm 22A in the radial direction, and the pressing hand 22C was pressed in the radial direction to enlarge the parison. Thereafter, the parison enlarging member 22 was reduced using the cylinder device 31.

Furthermore, as shown in FIG. 3, the mandrel 2 was further inserted into the enlarged parison 4, and the neck molding member 24 of the mandrel 2 was inserted into the parison. Next, the two molds were closed, the parison 4 was held in the cavity, and the molds were clamped.

Next, gas was introduced into the parison 4 through the gas introduction hole of the mandrel 2, and the parison 4 was molded along the mold surface of the mold 1. Thereafter, the molded product was cooled, the mold was opened, and the mandrel was pulled out to produce a hollow product having a predetermined hollow shape.

The hollow product manufactured as described above had precision in its shape and dimensions. Furthermore, since this device has an expansion mechanism directly on the mandrel, the blow molding mechanism is simple and the device can be made smaller and simpler.

[Effects of the Invention] The blow molding apparatus of the first invention includes a mold having a predetermined cavity shape, a distal end portion having a parison expansion member that can be inserted into the inside of the parison before expansion and expandable and contractible in the radial direction, a rear end portion having a neck molding member forming an inner surface of the neck portion larger than the inner diameter of the previous parison; a mandrel having a gas introduction hole for introducing gas into the parison; and the parison expansion member. It consists of an expansion/contraction mechanism for expanding/contracting the image. Therefore, since this apparatus has an expanding mechanism directly on the mandrel, the blow molding mechanism is simplified, and the apparatus is small and simple. Furthermore, according to the blow molding method of the second invention, in which a predetermined hollow product is manufactured using this apparatus, the parison can be expanded over a wide range and expanded into a shape close to the product shape, so that the parison stretching conditions are uniform. be converted into Therefore, according to this method, it is possible to manufacture a hollow product having a uniform thickness and precision in shape and size. The device and method are suitable for manufacturing automotive boots, dust covers, etc.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a state in which a mandrel is partially inserted into a parison in an embodiment. Second
The figure is a schematic cross-sectional view of the parison in an expanded state in the radial direction in the embodiment. FIG. 3 is a schematic cross-sectional view of a state in which a mandrel is inserted into an enlarged parison and a mold is closed in the example. 1... Molding mold, 2... Mandrel, 21... Tip part,
22...Parison expanding member, 22A...Opening/closing arm, 22
B...Connection part, 22C...Pushing hand, 23...Rear end part, 2
4... Neck molding member, 3... Expansion/contraction mechanism, 31... Cylinder device.

Claims (1)

[Scope of Claims] 1. A mold divided into two or more parts that can be opened and closed and has a cavity shape according to the external shape of a hollow product having a wide neck at one end, and a mold that can be inserted into the inside of the parison before expansion and can be expanded and contracted in the radial direction. a distal end having a parison expansion member capable of expanding the parison, and a rear end having a neck shaping member forming an inner surface of the neck larger than the inner diameter of the parison before expansion, for introducing gas into the parison; A blow molding device comprising: a mandrel having a gas introduction hole; and an expansion/contraction mechanism for expanding/contracting the parison expansion member through the mandrel. 2. The parison expanding member includes a set of at least three opening/closing arms disposed in the circumferential direction of the tip of the mandrel, one end of which is pivoted to the tip of the mandrel and the other end of which opens and closes in the radial direction; Open and close arms,
Claim 1, wherein one end is pivoted to the opening/closing arm and the other end is pivoted to the mandrel so as to be movable relative to the mandrel in the axial direction of the mandrel. blow molding equipment. 3. The blow molding apparatus according to claim 2, wherein the parison enlarging member has a pressing hand that is pivotally supported at the tip of the opening/closing arm and that contacts the inner surface of the parison and presses it in the radial direction. 4. The blow molding apparatus according to claim 2, wherein the expansion/contraction mechanism is a cylinder device composed of a piston and a cylinder. 5. The blow molding apparatus according to claim 1, wherein the parison expansion member is an expandable/contractable bag such as a rubber bag, and the expansion/contraction mechanism is a fluid pump that moves fluid into and out of the bag. 6. A first step of extrusion molding the parison; a tip portion having a parison expansion member that can be inserted into the parison and expandable and contractible in the radial direction; and a neck portion forming an inner surface of the neck portion that is larger than the inside diameter of the parison before expansion. a rear end portion having a forming member;
Inserting the tip of a mandrel having a gas introduction hole for introducing gas into the parison into the parison, and expanding the parison expansion member in the radial direction to expand the parison in the radial direction, a second step of shrinking the parison expansion member; a third step of further inserting the mandrel into the expanded parison; and inserting a neck forming member of the mandrel into the parison; two or more parts that can be opened and closed. a fourth step of closing the mold divided into molds and holding the parison in its cavity; and introducing gas into the parison from the gas introduction hole of the mandrel and moving the parison along the mold surface of the mold. A blow molding method characterized by comprising a fifth step of molding. 7. The parison expanding member includes a set of at least three opening/closing arms disposed in the circumferential direction of the tip of the mandrel, one end of which is pivoted to the tip of the mandrel and the other end of which opens and closes in the radial direction; Open and close arms,
one end is pivoted to the opening/closing arm, and the other end is pivoted to the mandrel so as to be movable relative to the mandrel in the axial direction of the mandrel, and a second
The blow molding according to claim 6, wherein the parison expanding step of the process includes driving the connecting portion in the axial direction of the mandrel to open the opening/closing arm in the radial direction to expand the parison in the radial direction. Method. 8. The second step, the parison enlarging step, is a blow blower according to claim 7, in which the parison is enlarged by pressing in the radial direction with a pressing hand that is pivotally supported at the tip of the opening/closing arm and comes into contact with the inner surface of the parison. Molding method. 9. The blow molding method according to claim 7, in which the process of expanding and contracting the parison uses a cylinder device composed of a piston and a cylinder. 10. The blow molding method according to claim 6, in which the parison expansion/contraction step involves introducing fluid into and out of an expandable/contractable bag such as a rubber bag.