JPH07276475A - Material replacement device for blow molding machine - Google Patents

Abstract

PURPOSE:To carry out the smooth material replacement and color change by forming a material replacement extraction channel on the die housing side of a manifold, boring an extraction opening on the opposite die housing side and forming slidably up and down an extraction opening on an outer mandrel in a ring passage between a die housing and the mandrel. CONSTITUTION:A manifold 20 bending in the extrusion direction while reducing the passage sectional area toward the opposite resin inflow inlet side of a mandrel 16 is formed. A die 10 is provided with a joining section 27 formed by joining the manifold end from the resin inflow inlet side 21. A material replacement extraction channel 52 with a recessed section is formed on the side of a die housing 12 opposite to an upper end section of the manifold 20. A material replacement extrusion opening 50 is bored on the side of the die housing 12 opposite to the joining section 27, and an outer mandrel 36 is disposed slidably up and down in a ring passage between the die housing 12 and the mandrel 16 so that the material replacement extraction opening 50 can be opened and closed freely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material changing device for a blow molding machine.

[0002]

2. Description of the Related Art Conventionally, when performing blow molding by a blow molding machine, after the molten resin supplied from the extruder is stored in an amount corresponding to the quantity of the molded product, the plunger of an injection device (not shown) is moved. A parison is formed by discharging resin in a tube shape from a die discharge port, and air is blown to obtain a desired product. On the outer peripheral surface of the mandrel of such a blow molding machine die, there is 2 on the side 180 ° opposite to the resin supply port side of the die housing to which the discharge port of the extruder is connected.
A resin distribution passage having a shape in which the resins distributed in the direction join at the downstream portion is formed, and the molten resin is formed as a cylindrical parison.

[0003]

However, the resin distribution passage has a complicated flow passage shape, resulting in a portion where the flow of the molten resin is extremely slow, or a retention portion. This stagnation is particularly noticeable on the wall surface where the flow passage cross-sectional area is large and the flow velocity is slow, and at the corners or confluences where the flow passage shape changes. There is a problem that a large amount of resin and working time are wasted due to replacement of the old resin with the new resin that remains, resulting in a decrease in productivity.

Further, the resin may be deteriorated by staying in a high temperature atmosphere for a long time, and the deteriorated resin may be gradually peeled off during molding and mixed into a hollow molded product, resulting in deterioration of quality of the molded product. There is also a nature. Furthermore, as a conventional solution, there is a method of disassembling the die itself and directly removing the stagnant resin adhering and remaining inside, but it is necessary to stop the entire line every time the material is changed. However, the work was greatly affected, the operating rate of the device was lowered, and a long working time was required.

Further, since the weld line formed in the parison is eliminated by the stagnant resin staying in the joining part, a cleaning hole is formed in the vicinity of the joining part, and the stagnant resin is taken out from the hole and is not cleaned. There is also a method of plugging with a plug or the like at the time, that is, during normal operation. However, with only the cleaning holes locally arranged at the merging portion, the effect of removing old resin adhering and remaining on a wide stagnation portion such as the merging portion or the resin passage wall in the upstream region which is the source of the merging portion is small, Further, there is a problem that the resin remaining or deteriorated in the cleaning hole during the sealing plug blocks the hole itself.

It is an object of the present invention to provide a material changing device in a blow molding machine which can smoothly change the material or change the color by paying attention to the above conventional problems.

[0007]

In order to solve such a problem, according to the present invention, a mandrel is inserted into a die housing to form a resin passage, and a resin inlet from the accumulator side is formed in the resin passage. While opening, a manifold is formed which is branched from the surface of the mandrel on the resin inlet side to the left and right in the circumferential direction and is curved in the extrusion direction while reducing the passage cross-sectional area toward the anti-resin inlet side of the mandrel. A die in which a manifold end is merged from an inlet side to form a merged portion, and a material replacement extraction groove having a concave cross section is provided on the die housing side facing the upper edge portion of the manifold, and the merged portion is formed. A material change extraction hole is bored on the side of the die housing which faces the die housing, and is placed in an annular passage formed between the die housing and the mandrel. The openable outer mandrel material replacement for withdrawal hole provided vertically slidably.

[0008]

[Function] During normal operation of the hollow molded product, when there is no so-called material change or color change, the external mandrel is lowered to close the slit-like material change extraction hole, and conversely, the hollow molded product is molded. When not performing the so-called material or color change, the external mandrel is raised to completely open the material change extraction hole, and the old resin adhering and remaining in the die is extruded by the new resin, so that the old and new resin can be exchanged in a short time.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of a material changing device in a blow molding machine according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a partial cross-sectional front view of a die showing an embodiment according to the present invention, FIG. 2 is an explanatory view showing a state in which an external mandrel is raised and a resin is changed, and FIG. 3 is a state in which the external mandrel is lowered to change a material. Explanatory drawing showing a state in which the extraction hole is closed, FIG.
2 is a sectional view taken along line AA of FIG. 2, and FIG.
The cut sectional view seen from B is shown.

FIG. 1 is a blow molding die 1 according to an embodiment.
FIG. The die 10 has a die housing 12 formed of a round block, and a through-hole 14 having a substantially circular cross section is formed along the longitudinal center line. Such a through hole 14 is opened in the lower end surface of the die housing 12 in a state where the inner diameter is gradually reduced from the middle thereof to the lower end surface of the die housing 12.

A mandrel 16 having a diameter smaller than that of the through hole 14 is inserted into the die housing 12, and a resin passage 18 is formed between the outer peripheral surface of the mandrel 16 and the inner peripheral surface of the through hole 14. is doing. Mandrel 16
The lower end of the is formed by narrowing the tip according to the reduced diameter portion of the through-hole 14.

A parison control core 16 is provided at the lower end of the die 10 so that the mandrel 16 can move in and out.
b is attached. The parison control core 1
The front end of 6b faces the opening of the through-hole 14 and the through-hole 1
A mandrel lip 29 forming a circular ring-shaped resin discharge port 28 is integrally provided with the opening of No. 4.
Therefore, the die gap of the resin discharge port 28 can be arbitrarily changed by changing the in / out amount of the parison control core 16b.

The die gap is changed by changing the die housing 1.
2 is made possible by driving a control cylinder 30 fixed to a support plate 25 on a column 24 standing upright, and for this reason, a parison control rod 32 connecting the control cylinder 30 and the parison control core 16b is attached to a mandrel. It penetrates through 16.

The molten resin supplied to the resin inflow port 21 from the resin passage 22 connected to the accumulator 23 provided on the peripheral wall of the die housing 12 is first moved to the left and right in the circumferential direction from the surface of the mandrel 16 on the resin inflow port 21 side. Branch,
A manifold 20 having a semicircular cross section that is curved in the extrusion direction with a predetermined curvature is formed while gradually reducing the passage cross-sectional area toward the anti-resin inlet side of the mandrel 16 at a predetermined rate. The end of the manifold 20 is joined with the manifold 20 on the opposite side, which is symmetrical, from the resin inlet port 21 at a position of approximately 180 degrees.
Is formed.

In the present invention, with the above structure as a basic structure,
As shown in FIG. 1, in order to replace the old resin and the new resin that have stayed in the die 10 without moving, quickly, and completely, in particular, a portion where the resin is likely to stay, that is, on the manifold 20. This manifold 20 along the edge
On the side of the die housing 12 that faces the upper edge portion, a material changing extraction groove 52 having a concave cross section is engraved.

An annular passage 34 is provided between the inner wall surface of the die housing 12 and the outer diameter of the mandrel 16, and an external mandrel 36 which slides vertically along the annular passage 34 is provided therein. ing. The lower end of the outer mandrel 36 has the same shape extending from the upper edge of the manifold 20.

A plurality of external mandrels 36 are arranged on the support plate 25 at equal intervals (4 in this embodiment).
This is fixed to the tip of the rod 39 of the annular mandrel cylinder 38 and is configured to move up and down in the annular passage 34 by supplying and discharging pressurized oil or compressed air to and from the annular mandrel cylinder 38.

As shown in FIG. 3, the lower limit of the outer mandrel 36 is set slightly above the lower edge of the manifold 20, and the upper limit of the outer mandrel 36 is completely opened as shown in FIG. It is configured to be slightly above the material changing extraction hole 50.

Reference numeral 11 is an internal heater, 15 is an external heater, and 26 is a parison.

The operation of the blow molding die section configured as described above will be described. First, the external mandrel 36 is lowered to the lower limit position, and the material change extraction hole 50 is closed. Next, the resin that has flowed in from the resin inflow port 21 is branched leftward and rightward in the manifold 20 and flows down to the merging portion 2.
7 and the manifold 2 following the branch flow
The resin gradually overflows from the lower edge of 0, and the resin flows uniformly over the entire circumference of the resin passage 18. Since the groove sectional area of the manifold 20 is set to be gradually reduced,
The pressure distribution in the circumferential direction becomes uniform, and the parison is ejected as a parison having a uniform thickness.

After completion of such repeated extrusion molding of the blow-molded product, old resin adhering to and remaining at the upper edge portion of the manifold 20 or the merging portion 27 due to material change or color change is shortened with a new resin. When new resin is supplied from the accumulator 23 to the die 10 in order to efficiently replace the time, the parison 26 is discharged from the resin discharge port 28.
When the resin is extruded, the external mandrel 36 is raised to open the material change extraction hole 50, or the control cylinder 30 is actuated to raise the mandrel 16 and the opening of the resin discharge port 28 is set to zero. The external mandrel 36 may be raised to open the material change extraction hole 50.

As described above, when the external mandrel 36 is lifted to open the material changing extraction hole 50, the die 1
When a part of the new resin supplied from the resin inflow port 21 passes through the material change extraction groove 52 toward the merging portion 27 at the time of discharging the high-pressure new resin supplied to the No. 0, for example, 300 to 400 kg / cm ^2. In addition, the old resin remaining adhered along the upper edge of the manifold 20 can be discharged together.

By continuously holding or intermittently repeating such a series of operations, the remaining resin at the most apt to stay is eliminated, and the old resin is replaced with the new resin in a convenient and prompt manner. Become.

[0025]

As is apparent from the above description, in the present invention, the mandrel is inserted into the die housing to form the resin passage, and the resin inlet from the accumulator side is opened in the resin passage. Forming a manifold curved in the extrusion direction while branching left and right in the circumferential direction from the surface of the mandrel on the resin inlet side and reducing the passage cross-sectional area toward the side opposite to the resin inlet of the mandrel,
A die in which a manifold portion is formed by joining the manifold ends from the resin inlet side, and a material replacement extraction groove having a concave cross section is provided on the die housing side facing the upper edge portion of the manifold, and On the side of the die housing facing the confluence part, a material change extraction hole is formed,
Since the external mandrel is slidable vertically in the annular passage formed between the die housing and the mandrel so that the material changing extraction hole can be opened and closed, the external mandrel slides vertically in the annular passage,
The deteriorated residual resin can be scraped off, and the scraped old resin can be directly discharged from the material replacement extraction hole without discharging from the resin discharge port of the die. Rather than spot-like resin removal like conventional resin removal plugs, it is possible to remove deteriorated resin at one time over the entire circumference of the die, making it possible to change materials or colors very efficiently Can be used in a minimum amount. An external mandrel can also be used as an in-die accumulator. By using this together with the die lip control, it is possible to easily add the uneven thickness in the axial direction of the parison discharged from the die.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional front view of a die showing an embodiment according to the present invention.

FIG. 2 is an explanatory diagram showing a state where a resin is changed by raising an external mandrel.

FIG. 3 is an explanatory view showing a state in which an external mandrel is lowered and a material changing extraction hole is closed.

FIG. 4 is a sectional view taken along line AA of FIG.

5 is a sectional view taken along line BB of FIG.

[Explanation of symbols]

 10 die 12 die housing 14 through-hole 16 mandrel 16b parison control core 18, 22 resin passage 20 manifold 21 resin inlet 23 accumulator 26 parison 27 confluence portion 28 resin discharge port 30 control cylinder 34 annular passage 36 external mandrel cylinder 38 annular mandrel cylinder 50 Material Change Extraction Hole 52 Material Change Extraction Groove

Claims (1)

[Claims] 1. A resin passage is formed by inserting a mandrel into a die housing, and a resin inflow port from the accumulator side is opened in the resin passage, and the mandrel surface on the resin inflow side is branched to the left and right in the circumferential direction. A die in which a manifold that curves in the extrusion direction is formed while reducing the passage cross-sectional area toward the anti-resin inlet side of the mandrel, and the manifold ends from the resin inlet side are joined to form a joining part. And a material changing extraction groove having a concave cross section is provided on the side of the die housing facing the upper edge of the manifold, and a material changing extraction hole is formed on the side of the die housing facing the confluence portion. The external mandrel can be slid up and down in the annular passage formed between the housing and mandrel so that the material change extraction hole can be opened and closed. A material changing device in a blow molding machine, characterized in that