JPH0724907A - Method and apparatus for blow molding - Google Patents

Abstract

PURPOSE:To carry out a material change of parison promptly by moving a ring up and down with the use of resin pressure from respective extruders, and switching each flow passage within the cross-head. CONSTITUTION:The device is constructed such that each resin 2a, 3a consisting of different material from respective extruders 2, 3 is dropped from the nozzle 8 via respective passages 6, 7 of the cross-head, and a movement ring 21 mounted in vertically movable relationship at a position of respective passages 6, 7 crossed together is moved by resin pressure of any resin 2a, 3a so as to rapidly change each resin 2a, 3a supplied to the nozzle 8, thereby shortening two-layered portion of a joint in each resin 2a, 3a of parison.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow molding method and apparatus, and more particularly, it uses a resin pressure of resin from each extruder to move a ring up and down to switch each flow path in a crosshead. The present invention relates to a new improvement for quick switching of parison material.

[0002]

2. Description of the Related Art As a conventional blow molding method of this type, for example, Japanese Patent Publication No. 2-153 shown in FIG.
The method disclosed in Japanese Patent Publication No. 73 can be mentioned. That is, what is indicated by reference numeral 1 in FIG. 5 is a crosshead, and the first extruder 2 and the second extruder 3 are connected to the crosshead 1.

Each of the extruders 2 and 3 communicates with a first flow path 6 and a second flow path 7 provided in the crosshead 1 through first and second shutoff valves 4 and 5, respectively. The flow paths 6 and 7 are configured so as to merge in the nozzle 8.

Next, the operation will be described. First, when the first resin 2a is extruded from the first extruder 2 with the second shutoff valve 5 closed and the first shutoff valve 4 opened, the first resin 2a becomes the first resin 2a. It hangs as a parison 9 from the nozzle 8 via the flow path 6. Next, while the first shutoff valve 4 is closed and the second shutoff valve 5 is opened, the second extruder 3 pushes the second resin 3a made of a material different from the first resin 2a. Then, the second resin 3a is
It hangs as a parison 9 from the nozzle 8 through the flow path 7. Therefore, this parison 9 is a continuous parison 9 in which the first resin 2a and the second resin 3a are partially different.
Was obtained, and blow molding was performed using this parison 9.

[0005]

Since the conventional blow molding method is constructed as described above, the following problems exist. That is, in the above-mentioned conventional method, since the resin supply is controlled by the shut-off valve provided between each extruder and the crosshead, the continuous portion R of the two-layer resin in the parison is shown in FIG. As shown, it was getting longer. Therefore, for example, when molding a hollow molded product that uses a soft resin partially combined with a hard resin, it is ideal that the connection part of each resin is switched as sharply as possible. 6
In such a state, it was impossible to perform sharp switching.

The present invention has been made in order to solve the above problems, and in particular, the resin pressure of the resin from each extruder is used to move the ring up and down to make each of the flow passages in the crosshead. It is an object of the present invention to provide a blow molding method and device for performing switching, and for quickly switching the material of the parison.

[0007]

In the blow molding method according to the present invention, the first and second resins extruded from the first and second extruders and made of different materials are used for the first and second flow paths of the crosshead. In a blow molding method in which the nozzle is hung as a parison from a nozzle, a ring that is vertically movable at a position where each of the flow paths intersects is moved by a resin pressure of any of the resins, This is a method of switching the supplied resins.

More specifically, when the first resin from the first extruder is supplied to the first flow passage, the second pressure relief valve communicating with the second flow passage is opened, and the second pressure release valve is opened. When supplying the second resin from the extruder to the second flow passage, the first pressure relief valve communicating with the first flow passage is closed.

The blow molding apparatus according to the present invention includes first and second extruded materials of different materials.
In a blow molding apparatus in which a resin is hung as a parison from a nozzle via first and second flow paths of a crosshead, a ring provided vertically movable in a common flow path portion where the respective flow paths intersect. A first pressure relief valve provided in communication with the first flow passage and a second pressure relief valve provided in communication with the second flow passage, wherein the ring is provided with a resin pressure of each resin. It is configured to move up and down by.

More specifically, a fixed ring provided corresponding to the moving ring in the second flow path, a first tapered surface formed on the fixed ring, and a second tapered surface formed on the moving ring. The taper surfaces and the wedge-shaped voids formed between the rings when the taper surfaces are closely fitted to each other are wedge-shaped.

[0011]

In the blow molding method and apparatus according to the present invention, when the first extruder extrudes the first resin into the first flow path with only the second pressure relief valve on the second extruder side opened, 1
The moving ring rises due to the resin pressure of the first resin passing through the flow path, the second flow path is closed, and the first resin is supplied to the nozzle. Next, the extrusion from the first extruder is stopped and the first extruder on the first extruder side is stopped.
When the second resin is extruded into the second flow path from the second extruder with only the pressure relief valve opened, the moving ring descends due to the resin pressure of the second resin passing through the second flow path and the first flow Road closed, second
Resin is supplied to the nozzle. Therefore, the parison extruded from the nozzle is, as shown in FIG.
Immediately switching to the resin, it is possible to obtain a sharp switching without the sagging state as in the past. Further, due to the wedge effect of the wedge-shaped wedge gap formed between the fixed ring and the movable ring, a stronger force can be generated by the second resin against the resin pressure of the first resin to facilitate switching. Further, a high sealing effect of the first flow path can be obtained.

[0012]

The preferred embodiments of the blow molding method and apparatus according to the present invention will be described in detail below with reference to the drawings. It should be noted that the same or equivalent parts as those of the conventional example are designated by the same reference numerals for description. 1 and 2 show an apparatus to which the blow molding method according to the present invention is applied. FIG. 1 is a sectional view and FIG. 2 is a sectional view of a parison.

A reference numeral 1 in FIG. 1 is a crosshead, and a casing 1A of this crosshead 1.
A first extruder 2 and a second extruder 3 are connected to the.
A cylindrical nozzle head 1B is provided below the casing 1A.
Is fixed by a mounting screw 1C, and the nozzle head 1
A ring-shaped fixing ring 50 is provided on the outer periphery of the core 1D passing through B.
Is provided. In the hollow common flow passage portion 20 formed in the casing 1A, the first flow passage 6 and the second flow passage 7 divided by the cylindrical body 51 fixedly arranged in the common flow passage portion 20 are provided. The casing 1A is formed with a first channel inlet 6A and a second channel inlet 7A which communicate with the channels 6 and 7, respectively. Inner wall 51a of the cylindrical body 51
A movable ring 21 having a cylindrical shape is provided in the shaft so as to be movable up and down. The fixing ring 50
The first tapered surface 50a formed on the lower part of the outer circumference and the second tapered surface 21a formed on the lower part of the inner circumference of the moving ring 21.
And the third tapered surface 21b at the lower outer periphery of the moving ring 21 and the fourth tapered surface 1 formed at the lower inner periphery of the casing 1A.
Aa is configured to be closely fitted to each other, and as shown in FIG. 3, when the tapered surfaces 50a and 21a are tightly fitted to each other, a wedge effect by the wedge void 60 having a wedge shape is high. It is configured to obtain a sealing property.

Each of the extruders 2 and 3 passes through the first and second accumulators 2A and 3A, and the respective flow channel inlets 6A and 6A of the first flow channel 6 and the second flow channel 7 provided in the crosshead 1 are connected. 7A
The flow paths 6 and 7 are connected to each other at a common flow path portion 20 formed in the upper portion of the nozzle head 1B that constitutes the nozzle 8.

Between the extruders 2 and 3 and the flow paths 6 and 7 of the crosshead 1, the first and second pressure relief valves 30 and 3 are provided.
1 is connected, and by opening the pressure relief valves 30 and 31, the flow paths 6 and 7 are opened and the ring 21 is moved up and down. That is, the moving ring 2 is opened by the resin pressure of the resin passing through the second flow path 7 and the opening of only the first pressure relief valve 30 connected to the first flow path 6.
1 is lowered, the second flow path 7 is opened, and the second pressure relief valve 3
Due to the valve opening of only 1 and the supply of the resin to the first flow path 6, the moving ring 21 rises and is closely fitted to the fixed ring 50, and the second flow path 7 closes due to the sealing effect of the wedge gap 60, and the first flow Road 6 is opened.

Next, a case of actually performing blow molding with the above-mentioned structure will be described. First, with only the second pressure relief valve 31 on the second extruder 3 side opened, the first extruder 2
When the first resin 2a is extruded from the first channel 2 into the first channel 6, the moving ring is moved by the resin pressure of the first resin 2a passing through the first channel 6 as in the first resin extruded state (X) shown in FIG. 21 rises and is closely fitted to the fixed ring 50, the second flow path 7 is closed, and the first resin 2 a is supplied to the nozzle 8. Next, in a state where the extrusion from the first extruder 2 is stopped and only the first pressure relief valve 30 on the first extruder 2 side is opened, the second resin 3a is passed from the second extruder 3 to the second flow path 7 When extruded, the moving ring 21 separates from the fixed ring 50 and descends due to the resin pressure of the second resin 3a passing through the second flow path 7 as in the second resin extruded state (Y) of FIG. The flow path 6 is closed, and the second resin 3a is supplied to the nozzle 8.

Therefore, the parison 9 (shown in FIG. 2) extruded from the nozzle 8 is immediately switched from the first resin 2a to the second resin 3a, without the conventional two-layer sagging state. It is possible to obtain the parison 9 that is oblique and has a short two-layered portion.

[0018]

Since the blow molding method and apparatus according to the present invention are configured as described above, the following effects can be obtained. That is, since the moving ring provided in the flow path of the crosshead is moved up and down by the resin pressure of each resin from each extruder to switch each flow path, the conventional shutoff valve is used. Compared to the configuration,
Switching at the joint of the parison resin is carried out quickly, and the portion forming the two layers becomes short. Further, when closing the first flow path, the wedge effect located in the first flow path ensures the sealing effect of the first flow path. Also, this second
Even when the flow path is opened, the resin pressure is applied to the wedge voids, so that the moving ring can be easily lowered. Therefore, when blow molding a parison to form a hollow molded product, the material is sharply switched at a predetermined position, and a hollow molded product of a material requiring a plurality of characteristics can be easily manufactured with a high yield.

[Brief description of drawings]

FIG. 1 is a sectional view showing an apparatus applied to a blow molding method according to the present invention.

FIG. 2 is a sectional view showing a parison.

FIG. 3 is an enlarged cross-sectional view of FIG.

FIG. 4 is an enlarged sectional view of FIG.

FIG. 5 is a cross-sectional view showing a conventional configuration.

FIG. 6 is a sectional view showing a main part of a conventional parison.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crosshead 2,3 1st, 2nd extruder 2a, 3a 1st, 2nd resin 6,7 1st, 2nd flow path 8 Nozzle 9 Parison 20 Common flow path part 21 Moving ring 30 1st pressure relief valve 31 2nd pressure relief valve 21a 2nd taper surface 50a 1st taper surface 50 Fixing ring 60 Wedge gap

Claims (4)

[Claims] 1. A first and a second flow of a crosshead (1) are produced by using first and second resins (2a, 3a) of different materials extruded from a first and a second extruder (2, 3), respectively. In the blow molding method in which the nozzle (8) is hung as the parison (9) through the passages (6, 7), the movement is provided vertically movable at the position where the respective passages (6, 7) intersect. Ring (21) to each resin (2a, 3a)
The blow molding method is characterized in that the resin (2a, 3a) supplied to the nozzle (8) is switched by moving the resin with any one of the resin pressures. 2. A first resin (2a) from the first extruder (2).
When the gas is supplied to the first flow path (6), the second pressure relief valve (31) communicating with the second flow path (7) is opened, and the second extruder is opened.
When the second resin (3a) from (3) is supplied to the second flow path (7), the first pressure relief valve (30) communicating with the first flow path (6) should be opened. The blow molding method according to claim 1, which is characterized in that. 3. The first and second resins of the crosshead (1) are passed through the first and second resins (2a, 3a) of different materials extruded from the first and second extruders (2, 3). In a blow molding apparatus configured to hang as a parison (9) from a nozzle (8) via passages (6, 7), a common flow passage portion (2) where the respective flow passages (6, 7) intersect
0) a movable ring (21) vertically movable, and a first pressure relief valve (30) provided in communication with the first flow path (6).
And a second pressure relief valve (31) provided in communication with the second flow path (7), and the moving ring (21) is provided with the resin (2).
A blow molding device characterized in that it is configured to move up and down by the resin pressure of a, 3a). 4. A fixing ring (50) provided in the second flow path (7) corresponding to the moving ring (21), and the fixing ring.
When the first taper surface (50a) formed on (50), the second taper surface (21a) formed on the moving ring (21), and the respective taper surfaces (50a, 21a) are closely fitted to each other, The blow molding apparatus according to claim 3, further comprising a wedge-shaped void (60) formed between each ring (21, 50) and having a wedge shape.