JPH06155565A - Blow molding die - Google Patents

Abstract

PURPOSE:To efficiently perform the optimum replacement of a material by providing a plurality of stagnated resin discharge holes and performing the opening and closing timings of the holes by sequence control. CONSTITUTION:A stagnated resin discharge device 31 is constituted of a valve stem 32, a piston rod 32a, a contact element 32b, a plug 34 and a cylinder 35. Two resin discharge holes 33 are arranged at the positions of the resin stagnation parts 45 of both end parts of a mandrel along the same axis as the long axis of a core in the same direction as the axial line of the mandrel 13. In each of the resin discharge holes 33, the main resin discharge hole 33a communicating with a resin passage from the axial core part provided to the resin distribution part 19 of the core and the auxiliary resin discharge hole 33b communicating with the main resin discharge hole 33a on the way thereof and provided so as to be adjacent to the discharge hole 33a are arranged up to the midway of a resin material replacing passage 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die for a blow molding machine, in which materials and colors can be easily changed.

[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 storing the molten resin supplied from the extruder inside the die in an amount commensurate with the amount of the molded product, move the plunger of the injection device (not shown) to eject the resin in the form of a tube from the die discharge port to form a parison. To obtain the desired product. The outer peripheral surface of the core of such a die for blow molding machine is connected to the resin feed 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 two opposite directions merge at the downstream portion is formed.

[0003]

However, it is difficult to completely remove the deteriorated resin from the resin distribution passage, and even when the resin is replaced, the resin remaining between the core metal and the inner wall of the die housing is completely removed. Removing it is a rather tedious task, and in such a case, the die itself had to be disassembled and cleaned. For this reason, there is a problem that the work time required for changing the material is increased and the productivity is reduced.

Further, at the above-mentioned resin merging point, the molten resin is likely to stay, and the staying time becomes long, and the molten resin deteriorates. This deteriorated resin causes a weld line in the molded product and deteriorates the quality of this portion. Therefore, in the past, in order to periodically remove the accumulated deteriorated resin, a cleaning hole is formed in the peripheral wall of the die housing corresponding to the confluence point, and the deteriorated resin is taken out to the outside by utilizing this hole. It is also possible to plug the plug tightly during non-cleaning, that is, during normal operation. However, as described above, in the method of providing the cleaning hole in the peripheral wall of the die housing, during injection, high injection pressure causes stress concentration on the die housing, which tends to weaken the strength. Especially, when a flat die is used, Due to the shape of the housing, opening a cleaning hole at the end of the major axis where stress is concentrated becomes a problem in terms of die strength.

In view of the above-mentioned conventional problems, the present invention aims to provide a die for a blow molding machine in a blow molding machine, which can smoothly change materials (that is, change materials, colors, etc.). To do.

[0006]

In order to solve such a problem, in a blow molding die according to the present invention, a resin flow channel (14) is provided between the die housing (12) and the inner circumference thereof.
A resin distributor (19) fitted to the inner circumference is provided on an upper part of a cored bar (18) having a resin passage (41) communicating with a resin inlet hole (41) provided in the resin distributor (19). 42) is provided through the resin distributor (19) in the diametrical direction, and
In the blow molding die (1) in which both ends of the resin passage (42) are communicated with the resin passage (14) through the groove (43) at the outer peripheral surface of the resin distributor (19), the resin inlet hole (4)
The resin material changing passage (40) directly communicating with the resin passage (14) is provided in a direction intersecting with the resin passage (42) in the plan view, and the resin inlet of the resin material changing passage (40) is provided. An opening / closing valve (63) for opening and closing a passage is provided on the inlet side communicating with the hole (41), and this opening is provided at the outlet side opening communicating with the resin flow passage (14) of the resin material change passage (40). A plug (34) having a gap between it and the inner surface of the portion is movably provided, and is openably and closably communicated with a resin material replacement passageway (40) to form a resin discharge hole (36) in a cored bar (18). Configure

[0007]

When the material is changed or the color is changed, the old resin is likely to stay, that is, the annular resin near the upper end of the cored bar fitted to the inner circumference of the cylindrical die housing through the annular resin passage. To prevent the resin flowing into the flow channel from staying for a long time and the molten resin from deteriorating, a new resin material change passage communicating with the resin flow passage on the resin inlet side has been newly installed. It flows out from the opened resin inlet hole to the resin flow path through the resin material changing passage. At this time, the outlet hole of the resin discharge hole is tightly closed to prevent new resin from flowing out. Therefore, the old resin material can be removed very easily, and the new resin material and the old resin material can be exchanged in a short time. Also, during normal hollow product molding without material change, the on-off valve on the inlet side of the resin material change passage is closed and the plug between the plug and the opening of the accumulated resin discharge device provided on the outlet side is loosely fitted. The resin flow at the resin retaining portion is constantly formed so that the resin does not stay in the middle while keeping the state (having the annular passage).

[0008]

1 to 4 show an embodiment of a blow molding die according to the present invention, FIG. 1 is a vertical sectional view thereof, and FIG. 2 is a partially cut vertical sectional view taken along the line BB of FIG. FIG. 3 is an enlarged view of a part of FIG. 1 showing the stagnant resin discharging device part, and FIG. 4 is C- of FIG.
FIG. 5 is a broken view taken along line C, and FIG. 5 is an enlarged view of a part of FIG. 1 showing the opening / closing valve opening / closing device section.

In the present invention, an embodiment will be described taking a flat die 1 (hereinafter referred to as die 1) having a particularly large amount of staying resin as an example. In FIG. 1, the die 1 has an outer peripheral surface 6
The die housing 12 has a rectangular shape a and an inner peripheral surface 6b oval, and includes an upper die housing 12a and a 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
A core metal 18 composed of 5 is fitted, and an elliptical resin flow path 14 having a corrugated cross section is provided between the core metal 18 and the inner peripheral surface 6b of the die housing 12.

Further, the resin flow path 14 is not provided between the resin distributing portion 19 which is substantially the upper half of the core metal 18 and the inner peripheral surface 6b of the die housing 12, and the resin distributing portion 19 is provided.
And the inner peripheral surface 6b are fitted tightly together. A resin inlet 41, which is connected to a resin extrusion port of an extruder (not shown), is formed in the resin distributor 19 from the peripheral surface toward the shaft core, and below the resin inlet 41. A resin passage 42, which communicates with this through a vertical hole 41 a in the shaft core portion, penetrates in the diametrical direction of the short side direction of the resin distribution portion 19 and has both ends opened to the peripheral surface of the resin distribution portion 19.

A pair of grooves 43, which communicate with the resin flow path 14 at the upper end thereof, are provided in the openings at both ends of the resin passage 42 along the peripheral surface of the resin distribution portion 19.
3 is formed in a mountain shape when viewed from the front so as to communicate with the resin passage 42 and become wider toward the resin passage 14. Further, in the communication portion between the groove 43 and the resin flow passage 14, a part between both wall surfaces which are adjacent to each other in the lateral direction of the resin flow passage 14, that is, the longitudinal direction of the resin passage 42 is completely or almost completely cut off. A thin horizontal plate-shaped ridge 44 having a width and an appropriate length in the longitudinal direction of the resin flow passage 14, that is, the direction orthogonal to the longitudinal direction of the resin passage 42 is provided below the opening of the resin passage 42. Is provided so as to extend in the circumferential direction corresponding to the side, and is configured so that the resin flowing out of the resin passage 42 and flowing in the groove 43 can be distributed to both sides of the ridge 44 in the horizontal length direction by the ridge 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 in the lower portion of the die body 1, and a flat annular slit 16 (die lip gap) is formed 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 a plunger of a 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 and a parison 17 is formed. It is like this.

Reference numeral 20 denotes a movable ring as a centering member having an oval annular cross section, which is supported by surrounding the core 15 by engaging a holding plate 23 and flange portions. The outer peripheral shape thereof is similar to the inner peripheral surface of the pressing plate 23 and is formed in an oval shape slightly smaller than this. A total of six centering bolts 24 are screwed into the holding plate 23, for example, two on the long side and one on the short side, with the tips contacting the outer peripheral surface of the movable ring 20. By selecting some of the centering bolts 24 and moving them back and forth, the movable ring 20 is moved in the front-back, left-right and horizontal directions to center the movable ring 20 and the core 15. There is. Reference numeral 45 indicates a resin retaining portion.

In the structure described above, according to the present invention, FIG.
As shown in, the location where the resin is likely to stay, namely,
The groove 43 is distributed from the resin inlet 41 to the resin passage 42.
A resin material changing passage 40 is provided so as to pass through the resin storage portion 45 (the place where weld lines are likely to occur) 45 which is the most remote. That is, below the resin inlet hole 41 that is connected to the resin extrusion port of a resin extruder (not shown) and is drilled up to the shaft core portion, the resin passage 4 communicating at the shaft core portion is provided.
A resin material replacement passage 40 is newly provided coaxially with the long axis of the cored bar 18 intersecting (substantially orthogonal) with 2.

The resin material changing passage 40 has an opening 40a on the inlet side of the resin material changing passage, one of which is opened at a shaft core portion communicating with the resin passage 42 from the resin inlet hole 41, and the other is the length of the core metal 18 described above. After being bored coaxially with the shaft, at the end, it diverges downward along the inner peripheral surface 66 of the die housing 12 and opens to the resin flow passage 14 of the resin material changing passage (40) at the outlet side opening (hereinafter It has a structure having a main resin discharge hole 33a.

An opening / closing valve 63 is provided at the inlet side opening 40a of the resin material changing passage 40, and the opening / closing valve 63 is disposed above the cored bar 18 symmetrically with respect to the center line of the cored bar 18. The opening / closing valve opening / closing device 60 is used to open and close freely, and the opening / closing valve 63 is opened / closed to open or close the inlet side opening 40a of the resin material changing passage 40.

The on-off valve opening / closing device 60 shown in FIG.
2, piston rod 62a, joint 62b, cylinder 65
It consists of As shown in FIGS. 2 and 5, the opening / closing valve 63 is arranged so as to be vertically movable by being fitted in the recess 66 in the same direction as the axis of the mandrel 13. The on-off valve 63 is fixed to the lower end of the valve rod 62, and the upper end of the valve rod 62 has a joint 62.
A piston rod 62a is provided which is engaged with the cylinder 65 via b and is capable of moving forward and backward.

On the other hand, a staying resin discharging device 31 as shown in FIG. 3 is arranged in the main resin discharging hole (outlet side opening) 33a of the resin material changing passage 40, and the resin is most likely to stay when a new resin is changed. The resin in the weld line section is forcibly washed out, and the old resin that remains attached is discharged.

The accumulated resin discharging device 31 shown in FIG. 3 has a valve rod 32, a piston rod 32a, a joint 32b, and a plug 3.
4 and the cylinder 35. Mandrel 13
Two resin discharge holes 33 are arranged in the same direction as the axis along the same axis as the long axis of the cored bar 18 at the resin retention portions 45 (symmetrical about the resin passage 42) at both ends. There is. The resin discharge hole 33 is a main resin discharge hole 33 that communicates with the resin flow path 14 from the shaft core portion formed in the resin distribution portion 19 of the cored bar 18.
An auxiliary resin discharge hole 33b is provided up to the middle of the resin material changing passage 40 so as to communicate with the main resin discharge hole 33a from the middle and to be formed adjacently. Main resin discharge hole 3
A narrowed portion 33c is provided between the sub resin discharge holes 33b that are adjacent to and communicate with 3a. This is the accumulated resin discharge device 3
When the first plug 34 moves up and down, the plug 34 deviates from the axial center of the main resin discharge hole 33a, and the plug 34 passes through the resin material replacement passageway (40).
This is because it is possible to form an annular passage between the outlet side openings of the.

The inner peripheral surface of the main resin discharge hole 33a that desires the resin flow passage 14 and the outer peripheral surface of the plug 34 fixed to the tip of the valve rod 32 are arranged in a loosely fitted state, with a gap between both surfaces, for example. It has an annular passage of 0.1 to 3 mm. On the other hand, valve stem 3
The upper end of 2 is engaged with a cylinder 35 via a joint 32b and provided with a piston rod 32a that can move forward and backward to connect them. During normal blow molding, the plug 34 is in the position shown by the solid line in FIG.

The operation of the die part configured as described above will be described. The resin inlet 4 of the die 1 extruded from the extruder
The molten resin supplied to the No. 1 is the resin distribution part 19 of the cored bar 18.
At the center, it moves to the central portion of the resin passage 42, 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 1
4, a ridge 44 that substantially blocks the resin flow passage 14 extends in the inner circumferential direction of the resin flow passage 14, and the resin flow is directed toward the resin flow passage 14. Since grooves 43 are provided on both sides in the longitudinal direction of the oval cross section of the passage 14, the molten resin is evenly distributed on both sides of the ridge 44 and spreads evenly into the groove 43. It is evenly distributed to each part of the flow path 14.

In the present invention, at the time of manufacturing a so-called normal blow-molded product in which the material is not changed or the color is not changed, the inner circumference of the main resin discharge hole 33a is formed at the forward limit of the plug 34 in the opening 33a at both ends of the resin change passage 40. The resin in the groove 43 continues to gradually flow in the main resin discharge hole 33a from the lower side to the upper side through the annular passage between the surface and the outer peripheral surface of the plug 34. The resin is discharged to the outside from the resin discharge hole 36 formed in the. A plug for a tight plug (not shown) can be removed from the outlet hole of the resin discharge hole 36 with a screw or the like.

This is done for the following two reasons. That is, the resin material change passage 40 after the material change is completed.
When the on-off valve 63 of is closed, the old resin staying in the resin material changing passage 40 receives heat history from the outside and solidifies, and the resin material changing passage 40 is closed or has a small diameter.
This is to prevent the new resin from expelling and removing the old resin in the resin retention portion 45 through the resin material changing passage 40 even if the on-off valve 63 is opened during the next material change.

Another reason is that during normal hollow product molding, the resin does not flow and does not deteriorate in the resin accumulating portion 45, that is, in the resin accumulating portion 45. While gradually flowing into the resin material replacement passage 40 through the annular passage between the inner peripheral surface of the main resin discharge hole 33a and the outer peripheral surface of the plug 34, the resin discharge hole 3
The resin retention part 45 is made to flow out from 6 little by little to the outside.
This is because the flow of the resin is caused in the vicinity of and the adhesion and residual of the old resin is prevented.

Further, a portion where the resin is particularly likely to stay with the material change or the color change, that is, the resin holding portion 45.
When it is desired to replace the old resin remaining with the new resin with the new resin, first, the outlet hole of the resin discharge hole 36 is tightly plugged with a plug or the like, and then the opening / closing valve 63 on the inlet side of the resin material changing passage 40.
3 is supplied with pressure oil or compressed air to the cylinder 65 of the opening / closing valve opening / closing device 60 and is supplied with pressure oil or compressed air to the cylinder 35 of the staying resin discharge device 31 to connect the tip plug 34 of the valve rod 32 to the position 2 in FIG. The main resin discharge hole 33a is completely opened by raising it to the retreat limit at the position shown by the dotted line.

Next, the new molten resin extruded from the extruder and supplied to the die 1 flows into the resin material replacement passage 40 having a smaller flow resistance through the resin inlet 41, while flowing into the resin passage 42 having a larger flow resistance. . The new molten resin that has flown into the resin material replacement passage 40 is
Since it is provided closer to the extruder, the old resin remaining in the resin material replacement passage 40 is relatively easily moved to the resin flow passage 14 side under the influence of the high pressure of resin delivery from the extruder. Can be discharged to.

By continuously holding or intermittently repeating such a series of operations, the remaining resin is eliminated at a portion where the resin is most likely to be retained, such as the location of the resin retaining portion 45, and the old resin is properly replaced with a new resin. It will be replaced soon and completely.

After the replacement of the old resin with the new resin is completed, the opening / closing valve 63 of the opening / closing valve opening / closing device 60 is lowered to close the resin material changing passage 40, and the plug 34 of the accumulated resin discharging device 31 is closed. It is lowered to the lower limit so that an annular passage is formed between the main resin discharge holes 33a. At this time, the plug for the tight plug at the outlet hole of the resin discharge hole 36 is removed and left open.

Next, the new molten resin supplied from the extruder to the die 1 flows down through the resin flow passage 14 formed between the upper die housing 12a and the mandrel 13, and between the lower die housing 12b and the core 15, and the mandrel. Core 15 at the lower end of 13 and lower die housing 12b
The parison 17 is extruded from the slit 16 formed in 1. After sandwiching this between male and female molds, a gas such as air is blown into the parison 17 and then the resin is cooled and fixed to obtain a hollow molded product.

Even during such repeated molding, the molten resin constantly 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 and out from the resin discharge hole 36. Since it is flowing in the direction, even when the plug 34 is raised to the retreat limit due to the material change of the resin or the color change, the resin discharge hole 33 is opened or closed by moving the needle valve forward and backward as in the conventional case. Unlike when you do
When the resin is blocked, the resin stays in the resin discharge hole 33 for a long time, the molten resin deteriorates and solidifies, and the resin does not flow even if the needle valve or the like is opened.
It is possible to easily remove the resin staying in the.

[0031]

As is apparent from the above description, in the present invention, the core metal (18) having the resin flow path (14) between the die housing (12) and the inner periphery of the die housing (12) is
A resin distributor (19) fitted to the inner circumference is provided, and a resin passage (42) communicating with the resin inlet hole (41) provided in the resin distributor (19) is provided in the resin distributor (19). Blow molding die (1) which is provided so as to penetrate through the resin passage (42) and communicates with both ends of the resin passage (42) through the groove (43) at the outer peripheral surface of the resin distributor (19) with the resin passage (14). In 1), a resin material replacement passageway (40) for directly communicating the resin inlet hole (41) and the resin passageway (14) is provided in a direction intersecting with the resin passageway (42) on the plan view. An opening / closing valve (63) for opening and closing the passage is provided on the inlet side communicating with the resin inlet hole (41) of the exchange passage (40) and communicates with the resin flow passage (14) of the resin material exchange passage (40). Move the plug (34) having a gap between the outlet side opening and the inner surface of this opening. Freely provided, the resin material sorting passage (4
Since the resin discharge hole (36) is provided in the core metal (18) so as to be openably and closably connected to (0), there is no restriction on the strength of the die, and high-speed and high-pressure injection is possible. In addition, by providing the retained resin extraction hole on the side of the core metal with a large amount of resin retention, old resin that adheres to and remains in the resin retention area is almost eliminated, and a greater effect in color change can be obtained. When a plurality of holes are provided, the optimal opening / closing timing can be efficiently controlled by performing sequence control. Further, by providing the annular passage between the outlet side opening of the resin material changing passage and the plug, the resin flows from the resin material changing passage to the resin discharge hole through the annular passage in the resin retaining portion, and Since there is no stagnation, material change can be easily performed, material change time and color change time are shortened, productivity is improved, resin is not wasted during preparatory work, and resin consumption is reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a die according to an embodiment of the present invention.

FIG. 2 is a partially cut vertical sectional view taken along the line BB of FIG.

FIG. 3 is an enlarged view of a part of FIG. 1 showing a staying resin discharging device part.

FIG. 4 is a view taken along a line CC in FIG.

FIG. 5 is an enlarged view of a part of FIG. 1 showing an opening / closing valve opening / closing device section.

[Explanation of symbols]

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 Bar 19 Resin Distributor 20 Movable Ring 23 Holding Plate 31 Retained Resin Discharge Device 32 Valve Rod 33, 36 Resin Discharge hole 33a Main resin discharge hole (opening on outlet side of resin material changing passage) 34 Plug 40 Resin material changing passage 40a Entrance side opening of resin material changing passage 41 Resin inlet 42 Resin passage 60 Opening / closing valve 63 Opening / closing valve 63

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Claims (1)

[Claims] 1. A resin distributor (19) fitted to the inner circumference of a core metal (18) having a resin flow path (14) between the die housing (12) and the inner circumference of the die housing (12). A resin passage (42) provided to communicate with the resin inlet hole (41) provided in the resin distribution portion (19) is provided diametrically through the resin distribution portion (19), and both ends of the resin passage (42) are provided. In the blow molding die (1) in which the portion is communicated with the resin channel (14) through the groove (43) at the outer peripheral surface of the resin distributor (19), the resin inlet hole (41) and the resin channel (14) ) Is provided in a direction intersecting with the resin passage (42) on the plan view so as to communicate with the resin inlet hole (41) of the resin material exchange passage (40). An opening / closing valve (63) for opening and closing the passage is provided on the inlet side, and a tree of the resin material replacement passage (40) is provided. A plug (34) having a gap between the outlet side opening communicating with the oil passage (14) and the inner surface of the opening is movably provided, and a resin material changing passage (4
Blow molding die characterized in that a resin discharge hole (36) is openably and closably communicated with the core metal (18).