JP2720367B2 - Blow molding machine dies - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms a resin cylinder called a parison by injecting a resin in a die, inserts the resin cylinder in a mold, and then blows gas such as air into the parison and cools it as it is. The present invention relates to a die of a blow molding machine for obtaining a hollow product.

[0002]

2. Description of the Related Art Conventionally, when performing blow molding by a blow molding machine, a flat die or a perfect circular die is used as a die. After the molten resin supplied from the extruder is stored in the die in an amount corresponding to the amount of the molded product, the resin is discharged in a tube shape from the die discharge port by moving a plunger of an injection device (not shown) to form a parison, and air is discharged. Blow to obtain the desired product. The outer peripheral surface of the core metal of the die for the blow molding machine is connected to the resin supply port side of the die housing to which the discharge port of the extruder is connected.
° A resin distribution path is formed in a shape in which the resins distributed in the two opposite directions merge at the downstream side.

[0003] However, it is difficult to completely remove the deteriorated resin from the resin distribution path, and it is troublesome to completely remove the resin remaining between the cored bar and the inner wall of the die housing even when the resin is replaced. In such a case, the die itself had to be disassembled and cleaned. For this reason, there has been a problem that the work time required for material replacement increases and productivity decreases.

[0004]

In order to solve the above-mentioned conventional problems, at the above-mentioned resin confluence point, the molten resin tends to stay and the residence time becomes longer, and the molten resin deteriorates.
A weld line is formed in the molded product by the deteriorated resin, and in order to reduce the quality of this part, conventionally, in order to periodically remove the accumulated deteriorated resin, a die housing corresponding to the confluence point is formed. It is conceivable that a hole for cleaning is made in the peripheral wall, and the deteriorated resin is taken out to the outside by using this hole, and is plugged with a plug during non-cleaning, that is, during normal operation. However, as described above, in the method of providing a cleaning hole in the peripheral wall of the die housing, stress is concentrated on the die housing due to a high injection pressure at the time of injection, and the strength is apt to be weakened. Forming a cleaning hole at the long-diameter end where stress concentration is applied due to the shape of the housing poses a problem in the strength of the die.

An object of the present invention is to provide a blow molding machine die for a blow molding machine capable of smoothly changing materials (that is, changing materials, colors, and the like) by focusing on the above-mentioned conventional problems. I do.

[0006]

According to the present invention, in order to solve the above-mentioned problems, the present invention is applied to an upper end portion of a metal core fitted through a resin flow path in an inner periphery of a die housing. A resin distribution portion is provided, which diametrically penetrates a resin passage communicating with the resin inlet through the resin distribution portion, and further communicates with a resin flow passage near the upper end of the core bar intersecting the opening of the resin passage. Then, at least one or more holes for extracting the retained resin are bored in the core metal, and a retained resin discharging device for opening or loosely fitting the hole for extracting the retained resin is provided.

[0007]

[Function] An annular resin near an upper end portion of a cored bar fitted to an inner portion of a cylindrical die housing through an annular resin flow path, in a place where old resin easily stays when material or color is changed. The resin that has flowed into the flow path has a loosely fitted state (having an annular passage) between the plug of the accumulated resin discharge device and the resin discharge hole, so that the resin does not accumulate in the middle of the resin. The flow is constantly formed, and when the plug is opened, the removal of the old material is extremely easy, and the replacement with the new material can be performed in a short time.

[0008]

1 to 4 show an embodiment of a die for a blow molding machine according to the present invention. FIG.
1 is a view showing the left half as viewed from the direction of arrow A in FIG. 1 and the right half is cut off along the line BB in FIG. 1, FIG. 3 is a cut front view of the accumulated resin discharging device, and FIG. FIG. 5 is a cutaway front view showing another embodiment shown in FIG.

In the present invention, an embodiment will be described by taking a flat die 1 (hereinafter referred to as a die 1) having a particularly large amount of retained resin as an example. In FIG. 1, a die 1 has an outer peripheral surface 6.
a die housing 12 having a rectangular shape and an inner peripheral surface 6b having an oval shape. The upper die housing 12a and the lower die housing 1
On the inner peripheral surface 6b of the die housing 12 composed of 2b,
Mandrel 13 and core 1 having an oval cross section
5 is fitted to the inner peripheral surface 6b of the die housing 12, and an elongated annular resin flow path 14 formed in a cross-sectional waveform is provided.

The resin flow path 14 is not provided between the resin distribution portion 19, which is substantially the upper half of the metal core 18, and the inner peripheral surface 6b of the die housing 12, and the resin distribution portion 19 is not provided.
And the inner peripheral surface 6b are fitted tightly. A resin inlet 41 connected to a resin outlet of an extruder (not shown) is formed in the resin distribution section 19 from the peripheral surface toward the shaft core. A resin passage 42 communicating with the shaft portion is penetrated in the short diameter direction of the resin distribution portion 19, and both ends are opened on the peripheral surface of the resin distribution portion 19.

A pair of grooves 43 communicating with the resin flow path 14 at the upper end thereof are provided along the peripheral surface of the resin distribution section 19 at both ends of the resin passage 42.
3 is formed in a mountain shape in a front view so as to communicate with the resin passage 42 and become wider toward the resin passage 14. Further, the communicating portion between the groove 43 and the resin flow path 14 completely or almost completely blocks a part between both wall surfaces in the short direction of the resin flow path 14, that is, in the longitudinal direction of the resin path 42. A thin horizontal plate-shaped ridge 44 having a width and an appropriate length in a longitudinal direction of the resin flow path 14, that is, a direction orthogonal to a longitudinal direction of the resin passage 42, is provided below the opening of the resin passage 42. The protrusions 44 extend in the circumferential direction corresponding to the sides, and are configured so that the resin flowing out of the resin passages 42 and flowing in the grooves 43 can be distributed to both sides of the protrusions 44 in the horizontal length direction by the protrusions 44. ing.

The die housing 12 comprises an upper die housing 12a and a lower die housing 12b. A lower die housing 12b surrounds the outer periphery of the core 15 around the core 15, and forms a flat annular slit 16 (die lip gap) between the core 15 and the lower die housing 12. The lower end of the resin passage is connected to the slit 16, and when the plunger of the resin injection device (not shown) is pushed forward, the molten resin in the resin passage 14 is pushed out of the main body through the slit 16 to form the parison 17. It has become.

Reference numeral 20 denotes a movable ring serving as a centering member formed in an oval annular shape, which is supported by engaging a holding plate 23 and a flange portion so as to surround the core 15 and has an outer periphery thereof. The shape is similar to the inner circumference of the holding plate 23 and is formed in an oval shape slightly smaller than this. A total of six centering bolts 24, for example, two on the long side and one on the short side, are provided on
The movable ring 20 is moved in the front and rear, left and right horizontal directions by selecting and moving some of the centering bolts 24 in contact with the outer peripheral surface of the movable ring 2.
The configuration is such that the centering of 0 and the core 15 is performed. Reference numeral 45 indicates a resin retaining section.

The operation of the dice configured as described above will be described. Resin inlet 41 of die 1 extruded from extruder
Is moved to the center of the resin passage 42 at the center of the resin distribution portion 19 of the cored bar 18, is distributed to both sides, and is discharged into the groove 43 from the opening on the peripheral surface of the resin distribution portion 19. The discharged molten resin flows through the groove 43 in the resin flow path 14.
A convex ridge 44 for substantially blocking the resin flow path 14 extends in the inner circumferential direction of the resin flow path 14, and the resin flow path 14 extends toward the resin flow path 14. Since the grooves 43 are provided on both sides in the longitudinal direction of the oval cross section of 14, the molten resin is uniformly distributed on both sides of the ridge 44 and spreads evenly within the full 43, and then the resin flows. It is evenly distributed to each part of the path 14.

The molten resin flowing down in the resin flow path 14 is provided with a passage resistance due to the resin flow path 14 being formed in a corrugated cross section, so that the molten resin flows toward the resin flow path 14 while being more uniformly distributed. , From the nozzle 16 as a parison 17 and extruded into the mold. At this time, since air is blown out from a blow hole (not shown) and is pressed into the parison 17, a hollow molded product is obtained.

However, after the series of hollow molded articles described above are obtained, when the next resin material change or color change is to be performed, the resin material is distributed from the resin inlet 41 to the resin passage 42 and then the groove is formed. 43, which is the farthest resin staying part 4
In some cases, some of the old resin stays still and does not move, and the old resin is hard to be replaced with new resin, which may cause deterioration.

[0017] Therefore, unless the old resin and the new resin that have stayed in motion have been completely and properly replaced quickly and completely, the labor, time, and waste of material at the time of material change, color change, and the like are not all over. Will be. If the material change or color change is insufficient, only a few, once every few shots to several tens of shots, will occur on the surface of the molded product during continuous molding, and the old resin before the change will appear and the molded product will be defective. Not only can it cause the problem of becoming unusual, but it can also cause other problems such as confusion in production planning and delays in delivery.

For this reason, in the present invention, the accumulated resin discharge device is disposed between the resin accumulation portion 45 which is most remote from the resin accumulation portion 45 which passes through the groove 43 after being distributed from the resin inlet 41 to the resin passage 42. 31 were provided.

The accumulated resin discharge device 31 shown in FIG. 3 comprises a valve rod 32, a joint 32b, a plug 34, a cylinder 35, and an attachment 37. In the same direction as the axis of the mandrel 13, a total of six stagnant resin discharge devices 31 are provided at left and right symmetric positions, for example, two resin discharge holes 33 on the long side and one on the short side. The main resin discharge hole 33a communicates with the resin discharge hole 33 from the upper end of the resin distribution portion 19 of the mandrel 13 to the groove 43 and the main resin discharge hole 33a. A hole 33 b is provided up to the upper end of the resin distribution section 19.

The inner peripheral surface of the main resin discharge hole 33a over which the groove 43 is desired and the outer peripheral surface of the plug 34 fixed to the distal end of the valve stem 32 are loosely fitted with each other. 1 to
It has a 3 mm annular passage. The attachment 37 provided at the upper end of the mandrel 13 is provided with a horizontal resin discharge hole 36 which forms a part of the discharge hole 33 through the vertical resin discharge hole 33. The upper end of the valve rod 32 is engaged with a cylinder 35 via a joint 32b, and a piston rod 32a is provided so as to be able to move forward and backward, and both are connected.

By supplying or discharging compressed oil or compressed air to / from the cylinder 35, the plug 34 moves forward and backward, and changes from the loosely-fitted state of the forward limit shown by the solid line in FIG. 3 to the fully opened state of the backward limit shown by the chain line in FIG. It has become.

With this structure, when it is desired to replace old resin remaining in the vicinity of the opening at both ends of the resin passage 42 with new resin due to material change or color change, the main resin discharge hole is already limited by the forward movement of the plug 34. The state in which the resin in the groove 43 gradually flows upward from below into the main resin discharge hole 33a through the annular passage between the inner peripheral surface of the plug 33a and the outer peripheral surface of the plug 34 is maintained.

Next, when the molten resin extruded from the extruder and supplied to the die 1 flows down the resin flow path 14 and begins to hang down as a parison 17 from the slit 16 at the tip of the die 1, the pressure is once applied to the cylinder 35. When oil or compressed air is supplied to raise the plug 34 at the end of the valve rod 32 to the retreat limit and fully open the resin discharge hole 33, the molten resin flows into the main resin discharge hole 33a and the sub-resin discharge hole 33b from the groove 33 side. Then, the resin is discharged from the resin discharge hole 36.

By continuously holding or intermittently repeating such a series of operations, there is no longer any stagnant resin at the place where stagnation is most likely to occur, and the old resin is quickly and completely replaced with new resin. In particular, in the present invention, the resin 11 supplied to the die 1 is
2a and the mandrel 13, and the resin flow path 14 formed between the lower die housing 12b and the core 15, and as a parison 17 from the slit 16 formed by the core 15 at the lower end of the mandrel 13 and the lower die housing 12b. Extruded. After sandwiching this between the male and female molds, gas such as air is blown into the parison 17,
Thereafter, when the resin is fixed by cooling, a hollow molded product is obtained.

Even during such repetitive molding, the molten resin continuously flows through the annular passage between the plug 34 and the resin discharge hole 33 and gradually flows from the groove 43 to the resin discharge hole 33 side. Even when the plug 34 is raised to the retreat limit due to the change or the color change, unlike the conventional case in which the resin discharge hole 33 is opened or closed by moving the needle valve or the like back and forth, the resin is closed when the resin is closed. The resin remaining in the groove 43 can be discharged without causing a problem that the molten resin degrades and solidifies in the discharge hole 33 for a long time, and the resin does not flow even when the needle valve or the like is opened. In the embodiment shown in FIG. 1, the resin discharge hole 36 having the resin discharge port is disposed above the metal core 18, but the resin discharge hole 33 is pulled out from the middle of the metal core 18 as shown in FIG. The resin discharge hole 36 may be provided on the side of the upper die housing 12a.

[0026]

As is apparent from the above description, according to the present invention, the inner periphery is fitted to the upper end of the core fitted through the resin flow path in the inner periphery of the die housing. A resin distribution section is provided, which diametrically penetrates a resin passage communicating with the resin inlet to the resin distribution section, and further communicates with a resin flow path near the upper end of the core bar intersecting the opening of the resin passage. By providing at least one or more holes for withdrawing the retained resin in the core metal and providing a retained resin discharging device for opening or loosely fitting the hole for withdrawing the retained resin, the strength of the die is restricted. High-speed, high-pressure injection becomes possible. In addition, by providing a hole for extracting the retained resin on the core metal side where the amount of retained resin is large, a greater effect can be obtained in terms of color change. More optimal material change can be efficiently performed by performing the sequence control. further,
The time required for material change and color change is shortened, the productivity is improved, and the resin consumption is reduced during the preparation work without wasting the resin.

[Brief description of the drawings]

FIG. 1 is a cut front view of a die according to an embodiment.

FIG. 2 is a view showing the left half of the die viewed from the direction of arrow A in FIG. 1 and the right half cut along line BB in FIG. 1;

FIG. 3 is a cutaway front view of the staying resin discharge device.

FIG. 4 is a view cut along line CC in FIG. 3;

FIG. 5 is a cut-away front view showing another embodiment shown in FIG. 1;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 die 12 die housing 12a upper die housing 12b lower die housing 13 mandrel 14 resin flow path 15 core 16 slit 17 parison 18 core metal 19 resin distributing section 20 movable ring 23 presser plate 31 stagnant resin discharge device 32 valve rod 33, 36 resin Discharge hole 23 Plug 42 Resin passage

Claims (1)

(57) [Claims] 1. A resin distribution portion fitted to the inner periphery is provided at an upper end of a core fitted through a resin flow path on an inner periphery of a die housing, and the resin distribution portion communicates with a resin inlet. Diametrically penetrates through the resin passage, and further communicates with a resin flow path near the upper end of the core, which intersects the opening of the resin passage, and at least one or more holes for extracting the staying resin are formed in the core. A die for a blow molding machine provided with a staying resin discharge device for opening or loosely fitting the staying resin extraction hole.