JP3397259B2 - Blow molding head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow molding head used in a blow molding machine which is one of plastic processing machines. 2. Description of the Related Art FIG. 5A shows an example of a longitudinal section of a conventional blow molding head 40. As shown in FIG. As shown in the drawing, a mandrel 43 having a core 45 having a funnel-shaped vertical cross section at the tip is movably arranged by a hydraulic cylinder 47 inside a hollow cylindrical head body 42 having a nozzle 41 at the tip. At the same time, by disposing the plunger 44 movably by the hydraulic cylinder 48 around the rod portion 46 of the mandrel 43, an annular resin supply path 49d is formed between the plunger 44 and the inner wall surface of the head main body 42,
Further, two resin passages 49 are provided vertically downward in the head main body 42 so as to be connected to the annular resin supply passage 49d.
c, and a parison supply channel 49a is formed in the inner wall portion of the head main body 42 so as to be connected at one place to the resin supply channel 49b for two-way flow. Then, the pipe joint 5 is attached to the head body 42.
3, a barrel 51 of an extruder 52 having a resin supply path 54 is connected to a screw 50 provided therein. [0003] The blow molding head 4 constructed as described above.
0, and in the state shown in FIG.
Plastic material (resin) supplied in a molten state from barrel 51 of resin supply paths 54, 49a, 49b, 49c
And accumulator chamber 49
e is filled with a plastic material, and while operating the hydraulic cylinder 47 to adjust the slit 56 formed between the nozzle 45 and the core 45 provided at the end of the mandrel 43, the hydraulic cylinder 48 is operated to operate the accumulator. The plastic material filled in the chamber 49c is extruded, and the parison 55 is extruded. However, in the conventional blow molding head 40 shown in FIG. 5A, a parison joining mark called a weld line is generated in the extruded parison 55.
FIG. 5B is a horizontal sectional view taken along the line AA of FIG. 5A, and FIG. 5C is a horizontal sectional view taken along the line BB of FIG. 5A. Hereinafter, the cause of the occurrence of the weld line will be described with reference to FIGS. 5 (a) to 5 (c). The plastic material supplied from the resin supply path 54 of the extruder 52 in FIG. 5A is sent through the resin supply path 49a and
In two resin passages 49c formed in the vertical direction from the branched resin passage 49b, they are diverted into two and pushed into the annular resin supply passage 49d in an annular shape, pooled once, and further around the plunger 44. As shown in FIG. 5C, the accumulator chamber 49 is pushed downward.
e. Accordingly, when the plastic material is pushed into the annular resin passage 49d from the resin passage 49c, the weld lines 57, 5
8 is formed. When a weld line occurs in the parison,
The weld line remains in the product, resulting in a decrease in the appearance quality of the product, and further, the thickness of the portion where the weld line mark occurs is reduced, so that the strength of the product is also reduced. In addition, when the material to be sent to the blow molding head is changed (including color change), the remaining material is mixed. Accordingly, the present applicant has disclosed in Japanese Patent Application Laid-Open No. 63-254.
As shown in FIG. 6, as a blow molding head 60 capable of eliminating the occurrence of a weld line according to Japanese Patent Application Laid-Open No. 009/009, a hollow cylindrical head body 63 that holds a nozzle 61 at the tip and extrudes a parison 66; A mandrel 64 which is concentrically and movably disposed inside the head body 63 while holding the core 65 at the tip end;
The mandrel 64 is formed so that a spiral lead groove 70 for extruding a parison is formed by a screw protrusion 71 between the mandrel and the inner peripheral surface of the mandrel.
Proposed a blow molding head 60 having a plunger 68 rotatably and movably provided on the outer periphery of a rod portion 67 of FIG. In the blow molding head 60, the upper part of the plunger 68 is rotatably fixed to a fixed base 73 by a rotary support 69, and the fixed base 73 is moved up and down by two elevating hydraulic cylinders 74, 74. A motor 77 is mounted on the elevating gantry 76, and the output of the motor 77 is transmitted to a drive shaft 75 via a rotary drive device 79 constituted by bevel gears 78, 78. Plunger 6 via drive wheel 80 installed at the lower end
The gear 81 fixed to the upper part of the gear 8 is rotated, and the plunger 68 is rotated. A plastic material 8 in a molten state from a hopper 82 is provided between a plunger 68 and a head body 63 which are rotatably and movably disposed by such a mechanism.
The plastic material 83 is supplied to the accumulator chamber 84 between the nozzle 61 and the mandrel 64 by rotating the plunger 68 and the hydraulic cylinder 7.
The slit 7 can be moved by moving the
The parison 66 is extruded while adjusting the dimensions of 2. [0010] The blow molding head 60 according to this proposal.
According to the method, since the supplied plastic material is extruded without being separated, no weld line is generated in the extruded parison 66. However, as a result of further studies by the present inventors, in the blow molding head 60 according to this proposal, in order to rotate and move the plunger 68, the head main body 63 is rotated. It has been found that it is necessary to secure a slight gap between the inner wall surface and the inner wall surface, and a thin film of a plastic material is generated, which remains as a residue in the lead groove 70. If the plastic material remains in the lead groove 70, the subsequent extrusion of the plastic material involves a wall thickness defect in a part of the parison, and a different material such as a material change or a color change. During extrusion, mixing of the previous plastic material with the next plastic material occurs. Therefore, in the manufacture of a product in which the material and color of the plastic material need to be changed, or where it is important to prevent the occurrence of scorch, the blow molding head 60 is periodically disassembled and cleaned, in particular, the lead groove. It was necessary to clean the inside of 70. The present invention has been made in view of the above-mentioned problems of the prior art, and has a helical lead groove in an outer peripheral portion thereof inside a hollow cylindrical head body and is rotatable and movable. An object of the present invention is to provide a blow molding head having a plunger, in which no plastic material remains in a lead groove. [0015] In order to solve the above problems, a blow molding head according to the present invention comprises a hollow cylindrical head body for extruding a parison, and a concentric interior of the head body. And a mandrel arranged to be movable in the direction of the rotation axis of the head main body, and rotatable with respect to the mandrel so as to form a lead groove for parison extrusion between the inner peripheral surface of the head main body. And a plunger provided on the outer periphery of the mandrel so as to be movable in the direction of the mandrel rotation axis, and further comprising a lead provided on a wall surface of the head main body. A lead groove scraper capable of fitting into the groove and detaching from the lead groove, and / or provided at the lower end of the plunger and at the outer periphery And a disk-shaped head body inner surface scraper which comes into contact with the inner wall surface of the head body by the provided convex portion. The blow molding head according to the present invention comprises a lead groove scraper provided on the wall surface of the head body and / or a head body inner surface scraper provided on the tip of the plunger. The plastic material remaining inside is scraped out by the lead groove scraper and / or the plastic material adhering to the wall surface of the accumulator chamber is scraped out by the scraper inside the head body. Further, the plastic material in a molten state in the accumulator chamber can be sufficiently stirred and kneaded by the scraper on the inner surface of the head body, and the plastic material in the accumulator chamber is uniformly kneaded. An embodiment of a blow molding head to which the present invention is applied will be described in detail with reference to the accompanying drawings. FIG. 1 is an explanatory view showing the situation when the plastic material is filled in the blow molding head H of the present invention.
FIG. 4 is an explanatory view showing a situation at the time of parison extrusion of the blow molding head H of the present invention. In FIG. 1, a fixing base 21 is a member that holds other components and serves as a skeleton. The elevating gantry 29 is disposed above the fixed base 21 by a fixed distance by the fixed arms 27 and 28. Further, a nozzle portion for extruding a parison and the like are provided at the center of the lower surface of the fixed base 21. First, the structure around the lifting frame 29 will be described in detail. A through hole 21a is formed in the center of the fixing base 21,
The mandrel 4 and the plunger 8 described later are inserted into the through hole 21a. The upper end of the mandrel 4 is extended above the fixed base 21 to reach the lower surface of the lift base 29,
Is connected to the mandrel lifting / lowering hydraulic cylinder 30 which is placed on the cylinder. That is, the mandrel 4 is held by the mandrel lifting / lowering hydraulic cylinder 30 so as to be vertically movable. On the other hand, the plunger 8 has an upper reduced diameter portion 8a.
And a hollow member having a stepped vertical cross-sectional shape having an enlarged diameter portion 8b at the lower portion and installed around the mandrel 4. The upper end of the plunger 8 is rotatably supported on the lower surface of the injection plate 22 which is held between the fixed base 21 and the elevating gantry 29 by the plunger elevating hydraulic cylinders 31 and 32 mounted on the elevating gantry 29 so as to be able to move up and down. 9 so as to be rotatable. A motor 23 is mounted on the upper surface of the injection plate 22, and a small gear 24 is connected to an output shaft of the motor 23. A large gear 25 meshes with the small gear 24, and the large gear 25 is fitted to the reduced diameter portion 8a on the upper part of the plunger 8. In addition, a flange 33 for preventing the plunger 8 from falling is installed in the reduced diameter portion 8a. Next, the structure around the nozzle unit 1 will be described in detail. A lead groove 10 for supplying a parison, which is formed by a spiral protrusion 11 formed on the outer peripheral portion, is provided around the enlarged diameter portion 8b below the plunger 8. The range around the lead groove 10 is about the stroke length of the plunger 8. The dimensions such as the depth of the lead groove 10 are appropriately determined according to the dimensions of the parison. An accumulator chamber 36 surrounded by the head body 3 is formed below the plunger 8. A nozzle 1 is provided below the head body 3 with a spacer 2 interposed therebetween. On the other hand, a funnel-shaped core 5 is disposed below the mandrel 4, and the width of the slit 15 formed between the nozzle 1 and the core 5 is increased by the mandrel 4 moving up or down. Is adjusted. A barrel 17 of an extruder 18 having a supply hole 20 formed in the outer periphery of the screw 16 is connected to a side portion of the head body 3 via a pipe joint 19, and a molten plastic is connected to the lead groove 10. Material is supplied. The blow molding head H of the present invention is further provided with a hydraulic cylinder 14 which can be freely moved in and out of the side of the head body 3 in order to scrape out the plastic material remaining or adhering to the inside of the lead groove 10 or the wall surface of the accumulator chamber. At the lower end of the plunger 8, a lead groove scraper 13 is disposed, and at the lower end of the plunger 8, a disk-shaped head body inner surface scraper 34 that comes into contact with the inner wall surface of the head body by a convex portion 34a provided on the outer periphery. FIG. 3 is a horizontal sectional view showing an engagement state between the lead groove scraper 13 and the head body 3 with a part thereof omitted. As shown in the figure, a scraper moving hole 12 is formed in the head main body 3 so as to fit into a lead groove 10 provided around the outer periphery of the plunger 8, and a rear end is inserted into the scraper moving hole 12. A movable lead groove scraper 13 connected to the hydraulic cylinder 14 is provided. FIG. 4 is a horizontal cross-sectional view showing the head body inner surface scraper 34 installed at the lower end of the plunger 8. The disk-shaped head body inner surface scraper 34 is installed so as to be in contact with the inner circumferential surface of the head body 3 by the four convex portions 34a provided on the outer circumferential portion. Fixing to the plunger 8 is easily performed by, for example, screwing. The operation of the blow molding head H of the present invention configured as described above will be described with reference to FIGS. First, as shown in FIG. 1, by operating each of the hydraulic cylinders 30 to 32 up to the return limit, the previous injection is completed and the plunger 8 located at the lowermost position with respect to the head body 3 is raised. The injection plate 22 and the plunger 8 are arranged so as to be closest to the lifting frame 29. When the plunger 8 is raised, the extruder 1
The plastic material is supplied into the lead groove 10 from the nozzle 17 at 8. At this time, the hydraulic cylinder 14 is shifted to the limit, the lead groove scraper 13 is fitted into the lead groove 10, and the motor 23 is rotated. Plunger 8
Is rotated to scrape the plastic material remaining in the lead groove 10. Also, a head body inner surface scraper 34 installed at the tip of the plunger 8.
The rotation also causes the plastic material adhering to the inner wall surface of the accumulator chamber 36 to be scraped out and the plastic material stored in the accumulator chamber 36 to be sufficiently kneaded. That is, FIG. 1 shows a state in which the filling of the plastic material into the blow molding head H is completed. Next, as shown in FIG. 2, the size of the slit 15 is adjusted so that the parison 6 having a desired thickness can be obtained by adjusting the position of the mandrel 4 by the hydraulic cylinder 30 for raising and lowering the mandrel. The plunger elevating hydraulic cylinders 31 and 32 are operated to the limit, and the plunger 8 is moved downward with respect to the head main body 3. At this time, the motor 23 is stopped, the plunger 8 is not rotated, and the hydraulic cylinder 14 is operated to retract the lead groove scraper 13 to a position where the lead groove scraper 13 does not interfere with the rising plunger 8. Plunger lifting hydraulic cylinders 31 and 3
With the operation of 2, the plastic material filled in the accumulator chamber 36 is extruded as the parison 6 from the slit 15. In this way, one shot is extruded, and this is repeated thereafter. Modification In this embodiment, both the lead groove scraper 13 and the chamber inner surface scraper 34 are provided, but they may be provided separately one by one. The scraping effect can be ensured even if one by one. In this embodiment, when the plastic material is extruded, that is, when the plunger 8 is lowered, the plunger 8
And the fitting of the lead groove scraper 13 into the lead groove 10 are not performed, but they may be performed together. The mechanism for moving and rotating the plunger 8 is not limited to the mechanism exemplified in this embodiment.
A well-known mechanism as proposed in Japanese Patent Publication No. 254,094 is appropriately employed. The blow-molding head of the present invention is a blow-molding head having a plunger provided with a lead groove for parison extrusion, which is provided with a lead groove scraper and / or a head body inner surface scraper. With this configuration, the plastic material adhering to the inside of the lead groove, the wall surface of the accumulator chamber, and the like can be reliably scraped off every shot. Therefore, it is possible to solve the problem caused by the adhesion of the plastic material that accumulates over time when used continuously. The scraper on the inner surface of the head body has an effect of kneading the plastic material stored in the accumulator chamber, in addition to simply scraping off the remaining plastic material. Therefore, the blow molding head of the present invention makes it possible to eliminate the adhesion and remaining of the plastic material in the lead groove without generating a weld line. Therefore, a high quality parison can be manufactured, and the material and color of the plastic material can be reliably changed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing a situation when a plastic material is filled in a blow molding head according to the present invention. FIG. 2 is an explanatory view showing a situation at the time of parison extrusion of the blow molding head of the present invention. FIG. 3 is a horizontal cross-sectional view showing an engagement state between a lead groove scraper and a head main body, with a part thereof being omitted. FIG. 4 is a horizontal sectional view showing a head body inner surface scraper installed at a lower end portion of a plunger. 5 (a) is a vertical sectional view of a conventional blow molding head, and FIG. 5 (b) is a horizontal sectional view taken along a line AA in FIG. 5 (a). c) is B- in FIG.
It is a horizontal sectional view in the B section. FIG. 6 is an explanatory view showing a configuration example of a conventional blow molding head. [Description of Signs] 1 Nozzle 2 Spacer 3 Head body 4 Mandrel 5 Core 6 Parison 8 Plunger 8a Reduced diameter section 8b Increased diameter section 9 Rotation support section 10 Lead groove 11 Screw protrusion 12 Scraper moving hole 13 Lead groove scraper 14 Hydraulic cylinder 15 Slit 16 Screw 17 Barrel 18 Extruder 19 Pipe Joint 20 Supply Hole 21 Fixed Base 21a Through Hole 22 Injection Plate 23 Motor 24 Small Gear 25 Large Gear 27, 28 Fixed Arm 29 Elevating Stand 30 Mandrel Elevating Hydraulic Cylinder 31-32 Elevating Plunger Hydraulic cylinder 34 Head body inner surface scraper 34a Convex portion 36 Accumulator chamber H Blow molding head

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yoshiharu Shitara 1-Shin-Nakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Pref. Ishikawajima-Harima Heavy Industries Co., Ltd. No. 1 Haramachi Ishikawajima-Harima Heavy Industries Co., Ltd.Technical Research Institute (72) Inventor Takashi Shimizu No. 1 Shin-Nakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Ishikawajima-Harima Heavy Industries Co., Ltd. 206527 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 49/00-49/80

Claims (1)

(57) [Claims 1] A hollow cylindrical head body for extruding a parison, and arranged concentrically inside the head body and movably in the rotational direction of the head body. Between the mandrel and the inner peripheral surface of the head main body so as to be rotatable with respect to the mandrel so as to form a lead groove for parison extrusion and to be movable in the mandrel rotation axis direction. A blow molding head comprising a plunger provided on the outer periphery of the mandrel, and further provided on a wall surface of the head main body and capable of being fitted into and detached from the lead groove. A disk-shaped head that comes into contact with the inner wall surface of the head body by a lead groove scraper and / or a protrusion provided at a lower end portion of the plunger and provided at an outer peripheral portion; Blow molding head, characterized in that it comprises a body surface scraper.