JPH04298320A - Blow molding machine - Google Patents

Abstract

PURPOSE:To provide a blow molding machine wherein troubles are not produced in molding and drawing down of a molding material due to the residual pressure of said material can be prevented. CONSTITUTION:In a passage 13 of molding material 2 from an extruder to a head 11 for extruding a parison 14 an accumulator 20 is formed. The accumulator 20 is provided with a storing section 21 and an extruding cylinder 25. The section 21 includes a plunger 23, on the side wall 22, which is moved by the pressure of the molding material 2 itself to increase the volume of the section 21 when the pressure of the material 2 rises. The extruding cylinder 25 has a piston rod 26 which can be detached from the plunger 23 and can press the plunger 23 so as to decrease the volume of the section 21.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow molding machine that extrudes a parison in order to mold blow molded products such as air cleaner hoses made of synthetic resin or rubber.

0002

[Prior Art] Conventionally, multilayer blow molded products made of multiple types of materials, for example, both ends are made of TPE (thermoplastic elastomer) and the middle part is made of PP (polypropylene).
When forming an air cleaner hose from
A blow molding machine M0 as shown in FIG. 4 was used.

[0003] This blow molding machine M0 is equipped with an extruder 3 for TPE and an extruder 7 for PP.
Main body 4/8, injection cylinder 5/9, and plunger 6/
It is equipped with 10. Further, a flow path 12 for TPE from the extruder 3 is formed in the head 11 that extrudes the parison 14, and a flow path 13 for PP from the extruder 7 is formed in the head 11.
It is connected to the flow path 12 at a position on the lower side of.

[0004] When blow molding an air cleaner hose by extruding the parison 14, the extruder 3.
7 as appropriate, and from the head 11, TPE1 and PP2.
・TPE1 was being pushed out sequentially.

[0005]

[Problems to be Solved by the Invention] However, in the conventional blow molding machine M0, even after the operation of the extruder 7 is stopped, the residual pressure of PP2 in the flow path 13 causes the As shown, PP2 sank into the flow path 12 of the TPE1, and as shown in the lower part of FIG. 6, the PP2 was to be mixed into a part of the parison 14a of the extruded TPE1.

[0006] In this way, when PP2 is mixed into a part that would normally be occupied by TPE1, when that part is reused as a residual material after molding, it becomes difficult to collect only TPE1, and the part is reused. I won't be able to do that. Therefore,
This resulted in a decrease in material yield.

[0007]The fact that the molding material sag due to residual pressure after the extruder stops operating is a problem not only when molding multi-layer blow-molded products but also when molding single-layer blow-molded products. As a result, the distance between the blow molding die and the head must be increased, resulting in the problem of increasing the space of the blow molding machine.

The present invention solves the above-mentioned problems, and aims to provide a blow molding machine that can prevent the molding material from dripping due to the residual pressure of the molding material without causing any hindrance to the molding. purpose.

[0009]

[Means for Solving the Problems] The blow molding machine according to the present invention includes a blow molding machine from an extruder to a head for extruding a parison.
An accumulator part is formed in the flow path of the molding material,
The accumulator section is configured to include an accommodating section and a pressing means, and the accommodating section is moved against the peripheral wall by the pressure of the molding material itself when the pressure of the molding material increases, thereby expanding the volume of the accommodating section. The apparatus is characterized in that it includes a moving wall, and the pressing means includes a pressing part that can be detached from the moving wall and can press the moving wall so that the volume of the storage part can be reduced.

0010

[Operations and Effects of the Invention] In the blow molding machine according to the present invention, after the extrusion of the molding material from the extruder is stopped, when the residual pressure of the molding material acts in the flow path of the molding material, the accumulator section The residual pressure is eliminated because the movable wall of the accommodating section moves to expand the volume of the accommodating section due to the residual pressure. As a result, dripping of the molding material is prevented.

[0011] Thereafter, when extruding the molding material from the head, the movable wall of the accommodating part is pressed by the pressing part of the pressing means to return the accommodating part to its original volume.

[0012] Then, immediately after stopping the extrusion operation from the extruder, the pressing portion of the pressing means may be separated from the movable wall so as not to create resistance when residual pressure is applied thereafter.

[0013] Furthermore, in the blow molding machine according to the present invention,
When expanding the volume of the storage portion, the movable wall is not forcibly moved, but is moved using the residual pressure of the molding material. That is, when the moving wall is forcibly moved to expand the volume of the accommodating portion, there is a risk that air may be mixed into the molding material around the moving wall, causing defects in the blow-molded product. However, in the blow molding machine according to the present invention, the residual pressure of the molding material is used to move the movable wall, so there is no risk of air getting mixed into the molding material, and molding is not hindered.

Therefore, the blow molding machine according to the present invention can prevent the molding material from sagging due to the residual pressure of the molding material without causing any hindrance to the molding.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Note that the same members as in the conventional example are given the same reference numerals.

As shown in FIG. 2, the blow molding machine M1 of the embodiment is used for blow molding an air cleaner hose in which both ends are made of TPE and the middle part is made of PP, as in the conventional case. It is what you use.

[0017] This blow molding machine M1, like the conventional one,
It is equipped with an extruder 3 for TPE and an extruder 7 for PP, and each extruder 3, 7 is equipped with a main body 4, 8, an injection cylinder 5, 9, and a plunger 6, 10. Also, parison 14
A flow path 12 for TPE from the extruder 3 is formed in the head 11 for extruding the product, and a flow path 13 for PP from the extruder 7 is formed.
is connected to the flow path 12 at a position on the lower side of the head 11.

Note that 15 is a shut-off valve. Further, the flow passages 12 and 13 are formed in the head 11 so as to have an annular opening cross section toward the lower part, as in the conventional case.

[0019]The blow molding machine M1 of the embodiment includes:
As shown in FIGS. 1 and 2, an accumulator section 20 is formed below the head 11 in the PP flow path 13.

The accumulator section 20 includes a storage section 21 disposed below the head 11 and an extrusion cylinder 25 as a pressing means.

The accommodating portion 21 includes a cylindrical side wall 22 fixed to the outer peripheral surface of the head 11, and a plunger 23 that fits into the inner periphery of the side wall 22 and becomes a movable wall as a part of the side wall 22. It is surrounded and communicated with the flow path 13.

The plunger 23 is prevented from coming off the side wall 22 by a piston rod 26, which will be described later. In addition, the configuration of the side wall 22 and the plunger 23 is such that a sufficient volume is secured within the housing portion 21, so that even if the plunger 23 retreats by absorbing the residual pressure, when the piston rod 26 retreats, the plunger 23 will not move into the piston rod 26. It is configured so that they do not come into contact with each other. Furthermore, 24 is a sealing material.

The extrusion cylinder 25 is supported by a bracket 27 extending from the outer peripheral surface of the head 11, and is configured to be operated by fluid such as air or hydraulic pressure. This extrusion cylinder 25 is equipped with a piston rod 26 as a pressing part, and the tip of the piston rod 26 is arranged at a position where it can be detached from the plunger 23 and can press the plunger 23 so that the volume of the housing part 21 can be reduced. There is.

In the case of the embodiment, the pressure of the PP2 extruded by the plunger 23 in the extrusion cylinder 25 is 1.2 to 1.5 of the pressure of PP2 extruded by the injection cylinder 9.
It is structured in such a way that it can secure twice as much.

Further, this extrusion cylinder 25 is controlled by a control circuit (not shown) of the blow molding machine M1. Specifically, as shown in the time chart of FIG. 3, when the PP2 injection signal is output from the control circuit (not shown) to the extruder 7, the piston rod 26 is moved from the backward position to the forward position while pressing the plunger 23. and further,
After the extrusion of PP2 from the extruder 7 is stopped, the piston rod 26 is controlled to retreat.

Note that, after the plunger 10 of the injection cylinder 9 of the extruder 7 pushes out the PP2 and moves to the forward end, it gradually retreats as the plunger 10 is filled with the PP2 from the main body 8. Incidentally, at this time, the shutoff valve 15 of the flow path 13 on the extruder 7 side is closed.

Next, the operation mode of this embodiment will be explained. The extruders 3 and 7 and the shut-off valve 15 are operated as appropriate to release the parison 1 of the TPE 1 from the head 11.
4a/PP2 parison 14b/TPE1 parison 1
4a is sequentially extruded, and the parison 14 is placed in a blow molding mold (not shown) which is being opened.

At this time, in the blow molding machine M1 of the embodiment,
After the operation of the extruder 7 is stopped and the shut-off valve 15 is closed, even if the residual pressure of PP2 remains in the flow path 13 in the head 11, the plunger 23 of the accommodating part 21 of the accumulator part 20 The residual pressure is eliminated because the housing section 21 moves so as to expand its volume due to the residual pressure. As a result, PP2 is prevented from dripping into the flow path 12 of TPE1, and TPE1 and PP2 do not mix with each other unnecessarily, and the parison 14a of TPE1 and the parison 1 of PP2
The parisons 14a of the TPE 4b and TPE 1 are extruded one after another from the head 11, and the parisons 14 are placed in a blow molding mold (not shown) that is being opened.

It should be noted that the PP2 accommodated in the housing section 21 is processed by the control circuit (not shown) when an injection signal for the PP2 is output from the control circuit (not shown) to the extruder 7 during the next molding cycle. Then, the piston rod 26 of the extrusion cylinder 25 is controlled to move from the retracted position to the forward position while pressing the plunger 23, so that the piston rod 26 is discharged into the flow path 13 and forms the parison 14b together with the PP2 from the extruder 7. I will do it.

Further, the plunger 23 of the accommodating portion 21 is controlled by a control circuit (not shown) so that the piston rod 26 of the extrusion cylinder 25 retreats immediately after extrusion of PP2 from the extruder 7 is stopped. Channel 13
Even if the residual pressure of PP2 builds up inside, the residual pressure moves backward to expand the volume of the accommodating portion 21, thereby eliminating the residual pressure.

After the parison 14 is placed in a blow-molding mold (not shown) that is being opened, the mold is closed and air is blown into the parison 14 to form a predetermined air cleaner hose.

Thereafter, by opening and releasing the mold, a desired air cleaner hose can be obtained, and by repeating the above steps, desired air cleaner hoses can be manufactured one after another.

[0033] Since the remaining material generated in each molding cycle is prevented from PP2 dripping into the parison 14a made of TPE1, it is easy to take out the molding material 1 alone and it can be easily reused. Therefore, the yield of the molding material 1 can be improved. Incidentally, in the case of the example, the conventional yield of 80% could be improved to 95%.

Furthermore, in the blow molding machine M1 of the embodiment, when expanding the volume of the storage portion 21, the plunger 23 is not forcibly moved, but is moved using the residual pressure of PP2. It is. That is, when the plunger 23 is forcibly moved to expand the volume of the accommodating portion 21, the molding material 2 around the plunger 23 is
There is a risk that air may get mixed in and cause defects in the air cleaner hose. However, in the blow molding machine M1 of the embodiment, the plunger 23 is moved using the residual pressure of PP2, so there is no risk of air getting mixed into the molding material 2, and no trouble occurs in molding.

[0035] In the examples, the case of molding a two-layer blow-molded product was explained, but of course the present invention can also be applied to the molding of a three-layer or more blow-molded product.
Furthermore, even when molding a single-layer blow molded product, by providing the accumulator section 20 as in the embodiment, dripping of the molding material can be prevented and the distance between the blow mold and the head can be reduced. , the space of the blow molding machine can be kept small.

Further, in the embodiment, the case is shown in which the accumulator section 20 is provided at a position below the head 11 in the flow path 13 on the side where dripping is to be prevented. This accumulator section 20 may be provided at a plurality of locations.
It may be provided on the upstream side of 3. However, if the accumulator section 20 is provided too far upstream of the flow path 13, the head 11
It is desirable to provide this at the lower end of the head 11 because the amount of PP2 remaining up to the lower end increases and the residual pressure cannot be effectively eliminated.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention, and is a partial cross-sectional view showing an accumulator section.

FIG. 2 is a schematic cross-sectional view showing the same embodiment.

FIG. 3 is a time chart showing the operation of the same embodiment.

FIG. 4 is a sectional view showing a conventional example.

FIG. 5 is an enlarged partial sectional view of a conventional head.

FIG. 6 is a sectional view showing a parison extruded in a conventional example.

[Explanation of symbols]

1... (molding material) TPE, 2... (molding material) PP, 3.7...Extruder, 11...Head, 12... (for TPE) flow path, 13... (for PP) flow path, 14...Parison, 20...Accumulator part, 21...accommodation section, 22... (peripheral wall) side wall, 23... (moving wall) plunger, 25... (pressing means) extrusion cylinder, 26... (pressing part) piston rod, M0/M1...Blow molding machine.

Claims (1)

[Claims] 1. An accumulator section is formed in the flow path of the molding material from the extruder to the head for extruding the parison, and the accumulator section is configured to include a storage section and a pressing means, The accommodating portion is provided with a movable wall on the peripheral wall that moves under the pressure of the molding material itself to expand the volume of the accommodating portion when the pressure of the molding material increases, and the pressing means includes:
A blow molding machine characterized by comprising a pressing part that is detachable from the movable wall and that can press the movable wall so as to reduce the volume of the storage part.