JPH04216918A - Jushiseikeihinnoburooseikeihohooyobisochi - Google Patents

Abstract

PURPOSE:To control the wall thickness of one part of a product accurately when blow molding is conducted by using a parison, wall thickness of which is deviated in the circumferential direction. CONSTITUTION:The thick wall sections 2a, 2b of a parison 2, wall thickness of which is deviated in the circumferential direction, are pushed previously against the inner surface of a mold 14A prior to blow molding, thus ensuring specified wall thickness in said thick wall sections 2a, 2b, then shaping other sections by blow molding.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for blow molding a resin molded article using a parison whose thickness is uneven in the circumferential direction.

0002

[Prior art] Blow molding, for example,
Molding in which a parison is formed in a hanging manner using an extruder as disclosed in Publication No. 212, the mold is clamped by sandwiching the parison from both left and right sides, and then pressurized gas is blown into the mold to form a resin molded product. In recent years, blow molding techniques for high-strength materials such as reinforcing resins have been developed, and the possibility of applying blow molding to structural members is increasing. However, when using resin molded products as structural members,
In order to ensure its performance, the part that receives the load needs to be formed with a thick wall, and the precision of the wall thickness is also required.

[0003] Regarding this, conventionally, when forming products with uneven wall thickness by blow molding, the width of the die slit of the extruder was variably controlled, or the width of the die slit was made uneven in the circumferential direction. By doing so, the thickness of the parison is uneven in the vertical direction or in the circumferential direction.

0004

[Problem to be Solved by the Invention] However, unlike injection molding, etc., in blow molding, only one side of the parison is pressed into the mold using internal pressure and shaped, resulting in a complicated product shape. This makes it difficult to control the wall thickness.

[0005] For this reason, it is difficult to obtain a product with the desired thickness distribution by simply performing blow molding using a parison with uneven thickness. Blow molding is extremely difficult to apply when the thickness needs to be precisely controlled.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to precisely control the wall thickness of a part of a product when blow molding is performed using a parison whose thickness is uneven in the circumferential direction. It is an object of the present invention to provide a method and apparatus for blow molding resin molded products.

[0007]

[Means for Solving the Problems] A method and apparatus for blow molding a resin molded product according to the present invention includes pressing a thick portion of a parison whose thickness is uneven in the circumferential direction against the inner surface of a mold before blow molding. Thus, after securing a predetermined wall thickness in the thick portion, the other portions are shaped by blow molding, thereby achieving the above object.

That is, the method of blow molding a resin molded article according to the present invention, as shown in claim 1, involves forming a hanging parison whose thickness is uneven in the circumferential direction so that the opposing portions are thicker;
◆Insert a pair of expander panels having contact surfaces that are approximately the same shape as a part of the inner surface of the blow molding mold into the space inside the parison that is formed to hang down, and then press these expander panels against each other. By moving the expander panel to the opposite side in the horizontal direction, the contact surface of each expander panel is brought into contact with each thick part of the parison, and the thick part is pressed against the inner surface of the blow molding mold, ◆The blow molding is then performed by closing the blow molding mold and blowing pressurized gas into the parison.

[0009] The blow molding apparatus for resin molded products according to the present invention also includes an extruder that hangs and forms a parison whose thickness is uneven in the circumferential direction so that the opposing portions are thicker; ◆A blow molding mold consisting of a pair of molds that clamp the parison formed by this extruder so as to sandwich it from the left and right sides, and ◆A part of the inner surface shape of this blow molding mold is approximately the same. It has a shaped contact surface,
a pair of expander panels inserted into a space within the parison formed by the extruder; an expander panel moving mechanism that brings the contact surface of each expander panel into contact with each thick-walled portion of the parison and presses the thick-walled portion against the inner surface of the blow molding die. It is characterized by this.

0010

As shown in the above structure, according to the present invention, the thick portion of the parison whose thickness is uneven in the circumferential direction is pressed against the inner surface of the mold before blow molding. Therefore, the thickness of the thick portion is determined at the time of pressing. Then, after a predetermined wall thickness is secured in some parts in this way, other parts are shaped by blow molding.

Therefore, according to the present invention, when performing blow molding using a parison with uneven thickness in the circumferential direction,
It is possible to precisely control the wall thickness of a part of the product. Furthermore, even if the product has a large degree of uneven thickness, it can be easily molded. As a result, a resin molded product suitable also for structural members can be obtained.

0012

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a plan sectional view showing an embodiment of the blow molding apparatus for resin molded products according to the present invention, and is
-I line sectional view. In addition, FIG. 2 shows II-I in FIG.
It is a sectional view taken along the I line.

As shown in these figures, the blow molding apparatus 10 includes an extruder 12 that hangs and forms a parison 2 with uneven thickness in the circumferential direction so that opposing portions on one diameter are thicker;
A pair of molds 14 are clamped to sandwich the parison 2 formed by the extruder 12 from both the left and right sides.
A parison comprising a blow molding mold 14 consisting of A and 14B, and an abutment surface 16a having approximately the same shape as a part of the inner surface of the blow molding mold 14, and formed hanging by an extruder 12. A pair of expander panels 16 inserted into the space within 2, and these pair of expander panels 1
6 to horizontally opposite sides of each other in the space within the parison 2.
The contact surface 16a of the parison 2 is brought into contact with each of the thick parts 2a and 2b of the parison 2, and the thick parts 2a and 2b are placed in the blow molding die 1.
Expander panel moving mechanism 18 that presses against the inner surface of 4
And, it is equipped with.

The extruder 12 transports the resin material, which is introduced into a hopper 20 and supplied by a screw 22 into a chamber formed between a die 24 and a core 26, by lowering a ring piston 30 driven by a cylinder 28. It is extruded through a die slit formed at the lower end between the die 24 and the core 26, thereby forming a substantially cylindrical parison 2 hanging down. The width of the die slit is not the same all around the circumference, and the opposed portion on one diameter is formed wider than the other portions. By forming the die slit in such a non-uniform width, A parison 2 having uneven thickness in the direction is formed. Note that the wall thickness of the parison 2 is determined by the hydraulic unit 32.
By raising and lowering the parison 2, the thickness can be uniformly changed all around the circumference, thereby making it possible to make the parison 2 uneven in thickness in the vertical direction.

The blow molding mold 14 has one mold 14A on which the thick portions 2a and 2b of the parison 2 are pressed by the pair of expander panels 16.
A pair of abutted surfaces 14Aa are formed.

The expander panel moving mechanism 18 includes:
Each expander panel 16 is provided with an expander pin 34 fixed to the expander panel 16, and the pair of expander pins 3
4 to the opposite side horizontally and expander panel 1.
6 movements are performed.

Next, the operation of this embodiment will be explained.

First, as shown in FIGS. 1(a) and 2, the above-mentioned parison 2 is formed to hang down using an extruder 12, and an expander panel 16 is inserted from below into the space inside the parison 2 formed to hang down. Once inserted, the expander panels 16 are moved horizontally opposite each other by the expander pins 34. As a result, Figure 1(b)
As shown in FIG.
a to each thick-walled portion 2a, 2b of the parison 2, and the thick-walled portions 2a, 2b are brought into contact with the abutted surface 14Aa of the mold 14A.
After pressing the expander panel 16 against the parison 2, the expander panel 16 is moved horizontally in the opposite direction to that described above and further moved downward to remove the expander panel 16 from the space inside the parison 2. Thereafter, as shown in FIG. 1(c), the blow molding mold 14 is clamped and pressurized gas is blown into the parison 2 to perform blow molding.

As detailed above, according to this embodiment,
The thick portions 2a and 2b of the parison 2, which have uneven thickness in the circumferential direction, are placed in advance on the contact surface 14 of the mold 14A prior to blow molding.
Since it is pressed against Aa, the thickness of the thick portions 2a and 2b is determined at the time of pressing. Then, after a predetermined wall thickness is secured in some parts in this way, other parts are shaped by blow molding.

Therefore, according to this embodiment, when performing blow molding using a parison whose thickness is uneven in the circumferential direction, it is possible to precisely control the thickness of a part of the product. Furthermore, even if the product has a large degree of uneven thickness, it can be easily molded. As a result, a resin molded product suitable also for structural members can be obtained.

In the above embodiment, when the expander panel 16 is horizontally moved in the opposite direction after the thick portions 2a and 2b of the parison 2 are pressed against the abutted surface 14Aa of the mold 14A, the expander panel 16 is moved horizontally in the opposite direction. Panda panel 16 is parison 2
The problem may be that it is difficult to leave.

Therefore, it is preferable to provide detachment facilitating means for facilitating detachment of the expander panel 16 from the parison 2 after this pressing is completed, and a specific example thereof is shown in FIG.
, shown in FIGS. 4 and 5.

The detachment facilitating means 40 shown in FIG. 3 is provided on the expander panel 16.

The detachment facilitating means 40 connects the expander panel 1 to an air passage 42 formed inside the expander panel 16 and communicates with the air passage 42.
a plurality of air jet holes 44 that open to the contact surface 16a of 6;
It consists of a compressor 46 and a control valve 48 that control the supply of air to the air passage 42. Then, the detachment facilitation means 40 performs vacuuming immediately after the expander panel panel 16 contacts the parison 2 to remove the expander panel 16 and the parison 2.
After the parison 2 is pressed against the mold 14A, the expander panel 16 is easily separated from the parison 2 by blowing out air from the air blowing holes 44 as shown in the figure. It has become.

Detachment facilitating means 50 shown in FIG. 4 is also provided on the expander panel 16.

The detachment facilitating means 50 is made of a flexible material that is fixed to the expander panel 16 over the entire circumference of the end face of the expander panel 16, as shown in FIG. 2(a). By providing such detachment facilitating means 50, it is possible to prevent the parison 2 pressed against the mold 14A from shrinking due to cooling and biting into the expander panel 16, as shown in FIG. It is now possible to do so. That is, as shown in FIG. 2(a), the shrinkage is absorbed by the deformation of the flexible material to prevent the material from biting. This flexible material can be selected from TPE, rubber, etc. depending on the temperature of the parison 2, etc.

The detachment facilitation means 60 shown in FIG.
It is installed in 4A.

This detachment facilitation means 60 includes a porous material (porous member) 62 constituting the abutted surface 14Aa of the mold 14A, a compressor 64 and a control valve 66 that absorb and control the air in this porous material. It is composed of an adsorption means consisting of. The detachment facilitating means 60 allows the parison 2 to contact the contact surface 14 of the mold 14A.
Immediately after being pressed against Aa, the parison 2 is vacuumed to attract it to the mold 14A, thereby making it easier to remove the expander panel 16, and conversely, after blow molding, the parison 2 is vacuumed. By blowing out the resin, it is possible to easily release the resin molded product.

By providing the detachment facilitating means 40, 50, or 60 as described above, the expander panel 16 can be easily detached from the parison 2 after the pressing is completed.

In addition to these effects, the detachment facilitation means 40 shown in FIG. 3 can remove voids between the expander panel 16 and the parison 2, and the detachment facilitation means 50 shown in FIG. According to the detachment facilitation means 60 shown in FIG. 5, the viscosity of the thick parts 2a and 2b of the parison 2 on the side of the mold 14A increases quickly. The thick portions 2a, 2b can be easily fixed in position during blow molding.

In the above embodiment, the expander panel 16 and the expander pin 34 are fixed to each other, and the expander panel 16 is removed from the space inside the parison 2 during blow molding. The panel 16 may be left fixed to the thick-walled portions 2a and 2b of the parison 2, and subsequent mold clamping and blow molding may be performed in this fixed state.

FIGS. 6, 7, and 8 are views showing specific examples of a mounting structure in which the expander panel 16 is removably attached to the expander pin 34 in order to enable the above-mentioned fixation to remain.

The mounting structure shown in FIG. 6 has an expander pin 34.
is formed into a hollow pipe shape, and the expander panel 16 is provided with a projection 16b projecting downward, and this projection 16b is inserted into the expander pin 34.

The mounting structure shown in FIG. 7 has an expander pin 34.
The upper end portion is formed into a crank shape, and an engaging portion 16c is provided at the lower end portion of the back surface (the surface opposite to the contact surface 16a) of the expander panel 16, so that the expander pin 34 and the expander panel 16 can be connected vertically. It is designed to engage in the direction.

The mounting structure shown in FIG. 8 has an expander pin 34.
A clamp mechanism 34a is provided at the upper end of the expander panel 16, and the clamp mechanism 34a engages and disengages the expander panel 16 from a protrusion 16d provided at the lower end of the back surface thereof.

In the mounting structure shown in FIGS. 6 and 7, it is necessary to move the expander pin 34 downward in order to remove the expander panel 16. In the mounting structure shown in FIG. 8, it is also possible to remove it by horizontal movement.

In this way, the expander panel 16
If the expander panel 16 is made to remain fixed to the parison 2, there is no need to consider problems such as ease of detachment of the expander panel 16 from the parison 2.
6 remains fixed to the resin molded product formed by blow molding, so this expander panel 16
can be used as a reinforcing material for resin molded products.

FIG. 9 is a diagram showing a seat back frame of a vehicle seat, which is a specific example of a resin molded product.

As shown in FIG. 4A, in the seat back frame 4, both side portions that particularly require strength are formed thickly, and the expander panels 16 remain fixed to the inner surfaces of the both side portions. Under pressure, they are trying to strengthen it.

The expander panel 16 shown in FIG. 2B is formed so that the wall thickness changes at each portion in the vertical direction on both sides depending on the degree of reinforcement. By doing this, it is possible to easily accommodate a seatback frame having the same shape as the seatback frame 4 but having different load conditions by simply changing the specifications of the expander panel 16. . Note that the material of the expander panel 16 in this case is preferably the same as that of the resin molded product.

In the expander panel 16 shown in FIG.
P), the resin without reinforcing material (
For example, it is made of PP or PE). As a result, when an excessive load is applied to both sides of the seat back frame 4, the flexible resin containing no reinforcing material can prevent the reinforcing material-containing resin from brittle fracture and scattering. can.

In the above embodiment, when the parison 2 is pushed out to the left and right by the expander panel 16, the upper end of the parison 2 (the part indicated by A in the figure) becomes extremely Since it will be bent, there is a concern that cracks may occur.

[0044] To deal with this, cracks can be prevented by providing a parison holding member 70, as shown in FIG. That is, the parison holding member 70 is swingably supported by the extruder 26, and a recess formed at its lower end engages with a protrusion formed at the upper end of the horizontally moving expander panel 16. It looks like this. Thereby, the parison holding member 70 swings together with the horizontal movement of the expander panel 16 and pushes the parison 2 outward, so that it is possible to prevent the parison 2 from being excessively bent.

[Brief explanation of the drawing]

FIG. 1 is a plan sectional view showing an embodiment of the blow molding apparatus for resin molded products according to the present invention, and is a sectional view taken along the line I-I in FIG.

[Figure 2] II-II line sectional view in Figure 1

[Fig. 3] Main part side sectional view showing an example of means for facilitating detachment

[Fig. 4] A plan sectional view showing another example of the detachment facilitating means.

[Fig. 5] Main part side sectional view showing still another example of the detachment facilitating means

[Fig. 6] A diagram showing an example of a removable mounting structure for the expander panel.

[Fig. 7] A diagram showing another example of a removable mounting structure for the expander panel.

[Fig. 8] A diagram showing still another example of a removable mounting structure for the expander panel.

[Fig. 9] A diagram showing a seat back frame that is a specific example of a resin molded product.

[Fig. 10] Main part side sectional view showing parison holding means

[Explanation of symbols]

2 Parisons 2a, 2b Thick wall portion 10 Blow molding device 14 Blow molding molds 14A, 14B Mold 16 Expander panel 16a Contact surface 18 Expander panel moving mechanism 40, 50,
60 Detachment facilitation means 50 Soft material 60 Adsorption means

Claims (7)

[Claims] Claim 1: A parison with uneven thickness in the circumferential direction is formed so as to hang down so that the facing portion has a thick wall, and a space inside the hanging parison is filled with a part of the inner surface of the blow molding die. By inserting a pair of expander panels having abutment surfaces of the same shape and moving these expander panels horizontally opposite to each other, the abutment surfaces of each of the expander panels are aligned with each of the parisons. The thick part is brought into contact with the inner surface of the blow molding mold, and then the blow molding mold is clamped and pressurized gas is blown into the parison. A blow molding method for resin molded products, which is characterized by performing molding. 2. The blow molding method for a resin molded product according to claim 1, wherein the mold clamping and the blow molding are performed with each of the expander panels remaining firmly attached to each of the thick portions. A blow molding method for resin molded products. 3. An extruder that hangs and forms a parison whose thickness is uneven in the circumferential direction so that opposing parts have thicker walls, and a pair of molds that clamp the parison formed hanging down by this extruder so as to sandwich the parison from both left and right sides. a blow molding mold consisting of a mold, and a space in the parison formed by the extruder to hang down, and having an abutment surface having substantially the same shape as a part of the inner surface shape of the blow molding mold. A pair of expander panels are inserted into the parison, and by moving the pair of expander panels horizontally opposite to each other in the space within the parison, the abutting surfaces of each expander panel are inserted into the parison. A blow molding apparatus for a resin molded product, comprising: an expander panel moving mechanism that is brought into contact with each of the thick parts and presses the thick parts against the inner surface of the blow molding die. 4. The blow molding apparatus for resin molded products according to claim 3, wherein each of the expander panels is pressed against at least one of the blow molding die and the expander panel after the pressing is completed. A blow molding apparatus for a resin molded product, characterized in that a detachment facilitating means for facilitating detachment from the parison is provided. 5. The blow molding apparatus for resin molded products according to claim 4, wherein the detachment facilitating means is provided in the blow molding die, and the detachment is completed at least after the pressing is completed. A blow molding apparatus for a resin molded product, comprising a suction means for suctioning the parison to the inner surface of the blow molding die. 6. The blow molding apparatus for a resin molded product according to claim 4, wherein the detachment facilitating means is made of a flexible material provided on an end face portion of the expander panel. Blow molding equipment. 7. The blow molding apparatus for resin molded products according to claim 3, wherein the expander panels are moved so that each of the expander panels remains fixed to each thick portion of the parison after the pressing is completed. A blow molding device for resin molded products, characterized in that it is removably attached to a mechanism.