JPS58187318A - Blow molding method - Google Patents

Abstract

PURPOSE:To control the thickness of a molded article partially by a method wherein a parison is arranged in split molds for blow molding, cooling gas is blasted partially on the above-mentioned parison and at the same time air is blown into the parison to be molded. CONSTITUTION:The parison 30 is arranged in split molds 21, 22 for blown molding, and cooling gas adjusted at a suitable temperature is blown from the cooling air outlet 25 located almost in the middle of a locally recessed part 24 very far from the axis of the parison 30. A part 30a of the parison 30 is cooled to a temperature lower than other parts 30b to decrease partial elongations and at the same time air is blown from the blowing nozzle 23 into the parison 30 to expand the parison 30. As a result thickness is stretched at the parts 30b hard to become thinner and finally the thickness becomes uniform all over the parison. The thickness can be controlled in this manner.

Description

[Detailed description of the invention]

[→←Ze Kazuaki (nonoshitt or minute! iIj] + Invention is to control meat 1! # in 5 minutes and mold it.
This invention relates to a blow molding method. [Invention J) Technical background and problems thereof] Controlling wall thickness in milling and blow molding
For example, the formula is as shown in Fang 1-? J, In the parison discharge nozzle (1), inside the die (2) 11
A mandrel (3) is provided in the section 7 so as to be movable up and down, and by moving this mandrel t3+ up and down, the die 121
By changing the width of the slit for discharging the parison (4) formed by the mandrel (3) and the mandrel (3),

[The thickness of the parison (4) is changed. However, in this so-called parison control method, a constant thick wall portion is formed in the circumferential direction of the parison (4), so it is difficult to apply it to objects with complex shapes such as gasoline tanks. Moreover, there is a problem in that an extra wall thickness is formed in areas other than those where it is desired to increase the wall thickness. . In order to solve this problem, as shown in Figures 1 and 1-2, the parison aυ is placed inside the split mold Q4 (11), and air is blown into the parison fitting υ from the blowing nozzle I. The parison Qυ is blown out from small holes with a number of S formed in a part of the cavity surface of the splitting a3 at a pressure higher than the blowing pressure from the blowing nozzle t141, and expands and expands to the next blow by blowing. A method has been proposed in which the parts are not directly in contact with each other in that part. According to this h method, considerable consideration is given to the local thin parts that depend on the shape, and the above-mentioned Compared to the parison control method, this is a useful method because it does not require the formation of thick parts that require military expense. However, in this method, it is difficult to provide a large number of small holes in the split 111, and If a porous material is used instead, the mold cost will increase, and in order to prevent the parison from coming into close contact with the mold surface, a large amount of air is blown against the outer ring of the parison, which speeds up the cooling of the parison and blows the parison out. In some cases, it is necessary to increase the pressure. [Objective of the Invention] The present invention is an attempt to solve the above-mentioned problems of the conventional method, and to make it possible to control the wall thickness of a molded product over a wide range and easily. [Summary of the Invention] The present invention provides a method for disposing a parison in a split mold for blow molding, and partially disposing a parison from a portion forming a cavity in the split mold. The present invention is characterized in that cooling gas is blown onto the mold to partially cool it, and molding air is blown into the baling ring to form the mold. Examples will be explained with reference to Figures 1'-6 and 4. Part (2) 4170-1 molding stamp, one of which @Ju
A blowing nozzle (c) is provided in the QIJ. In addition, a cooling gas outlet (
C) is provided, and a compressor (2) is wired to this cooling gas outlet (2) via a hot air vent (2) and a vent pipe surface. Then, in the same manner as in the conventional blow molding method, the carbonized gold fat is discharged through a parison discharge nozzle in a screw (not shown) to form a cylindrical parison (T). ) is opened in l1KK mff
Insert into 1lJυ(2) and parison (to)
Immediately after the lower end of 1■υ■
The parison 1 is then tightened by m, and air is blown into the parison 1 from the blowing nozzle 4, and the parison 1 is molded along the molding surface of 11υ(2), and the product is obtained by cooling and solidifying. At this time, immediately after the parison (to) passes the lower end of the split mold 121) (2), a recess is provided in the center of the partial recess (2) far away from the axis of the parison (to). From the cooling gas outlet (c), air is blown out as a cooling gas that is appropriately drawn according to the temperature (7).
By cooling a part (30-) to make it lower in temperature than the other part (30,1), the elongation is partially reduced, and at the same time, air is blown into the parison from the blowing nozzle (to) to make the parison ( ), and during this expansion and expansion, the part corresponding to general sK (30J) is thinned due to the partial decrease in elongation as described above.
In the end, a product with a uniform thickness or even thickness is obtained. In this way, as shown in JP51JAK, by applying the temperature-strain characteristics unique to synthetic resins and spraying gas at a temperature appropriate for each synthetic resin onto the parison, the characteristics of each synthetic resin can be adjusted. The thickness of the fishing rod can be controlled by making full use of this. Note that the cooling gas outlet (c) should be a direct hole as shown in Figure 16 if the target area to be thickened is narrow, or a hole as shown in Figure 16 if it is wide. The holes may be trumpet-shaped, and the hole shape may be selected depending on the shape of the product. In addition, when forming a partial thick part on a blow molded product,
For example, if you want to make the part where a self-tapping screw is driven thicker than other general parts, use the thicker part (30c) of the parison, like the 8th section.
By blowing relatively low temperature air, the elongation is reduced in other parts, and eventually a thickness close to that of the parison (7) is formed in some parts. Note that in reality, if the range to which the cooling gas is sprayed is too narrow, it will be difficult to match the intended thickness, so it is desirable to spray the cooling gas to a somewhat wider range. Furthermore, air, freon, or other gases may be used as the cooling gas. [Effects of the Invention] According to the present invention, cooling gas is partially blown onto the parison from the part forming the cavity in the splitter.
It is possible to easily control the wall thickness of a molded product over a wide range, which was conventionally influenced by the shape and difficult to take measures against partially thin internal parts. As a result, the thickness can be made uniform to be almost the same as other parts that are easily thinned, and it is also possible to increase the thickness in some parts.

[Brief explanation of the drawing]

) Figure 11 and Figure 2 are cross-sectional views 1 and t showing the conventional method.
Figure M shows #IT in a molded state, showing an example of the method of the present invention.
Figure 4 is a cross-sectional view of the molded product, Figure 5 is a material property diagram, Figures i6 and jP7 are cross-sectional views of the cooling gas outlet, and Figure 8 is a molding showing another example. It is a sectional view of the state. Qυ(2)...Side cover for blow molding, (2)...Partial recess, (2)--Cooling gas outlet, wire...Parison. 3rd vlI-7

Claims (2)

[Claims] (1) Place the parison in a split mold for blow molding, and blow cooling gas partially onto the parison from the cavity-forming part in the split mold [partially cool that part, A blow molding method that has the advantage of blowing molding air into the parison. (2) A claim in which the cooling gas from the cavity to the parison is blown from substantially the center of the recess of the cavity far from the axis of the parison. Blow molding force of 1 mL (3) The P6 cooling gas that is blown from the soil capacity to the parison has a special value of being kept at a temperature of 40%. Or the Pro-Search method described in Paragraph 2.