JPH0233511B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a hollow wood having an irregular three-dimensional structure and having an appearance similar to real wood grain, in which the grain spacing is varied by blow molding of synthetic resin. Concerning a method of manufacturing a body.

[Conventional technology]

Conventionally, in order to manufacture synthetic resin products with a wood grain appearance, there is a method of inserting a printed wood grain sheet into the inner surface of a mold and integrating the wood grain sheet into the surface by injection molding or blow molding. . In addition, in Japanese Patent Publication No. 45-8355, the parison is transferred along the double thread groove of the mandrel, extruded from the annular gap as two color-coded parisons, and then the mold is closed and blow molding is performed. A method of molding a hollow molded product that is color-coded in a spiral striped pattern is disclosed.

[Problem to be solved by the invention]

Among the above conventional techniques, the former method does not pose much of a problem when applied to objects with simple shapes, but it is difficult to apply when manufacturing molded objects with irregular three-dimensional structures. It was hot.

In addition, in the latter method, the two-color striped pattern approximates wood grain, but because the striped pattern is regularly color-coded in a spiral pattern, it is difficult to obtain a product with a natural wood grain appearance. I haven't reached it yet.

In view of these problems with the prior art, the present inventors have conducted research and have found that the raw materials retained in the crosshead of a crosshead type extruder are mixed into a different type of molten raw material to be extruded, and stripes are formed. By extruding the parison while revealing the grain pattern and blow-molding it using a mold with a cavity with an irregular three-dimensional structure, the border between AB and AB is not blurred, and the material has a pure wood grain-like appearance with different density at the bend. We succeeded in obtaining a hollow product.

That is, an object of the present invention is to continuously and efficiently manufacture a hollow body having a wood grain appearance.

[Means to solve the problem]

In order to achieve the above object, the method for manufacturing a wood-grained hollow body according to the present invention is to alternately feed raw materials A and B of different shades of tea to the supply port of a crosshead type extruder, and use a screw to alternately feed raw materials A and B into Molten raw material A that was transferred and melted sequentially and remained in the crosshead
Or, while B is mixed into the next extruded dissimilar molten raw material B or A, a parison is extruded while revealing a striped pattern in the vertical direction. Blow molding is performed using a mold, and the spacing of stripes corresponding to the wood grain can be changed in density depending on the blow ratio.

〔Example〕

Examples of the present invention will be described below.

FIG. 1 is a partially cutaway side view showing an example of a device suitable for carrying out the present invention, and FIG. 2 is an enlarged longitudinal sectional side view of the supply device. In the figure, reference numeral 1 denotes an extrusion device equipped with a crosshead 2, equipped with a horizontal extrusion screw 3 inside, and driven by a motor 4. 5
1 is a supply device, in which tanks 6 and 7 containing raw materials AB of different shades of tea are alternately supplied to a supply port 10 through supply channels 8 and 9, respectively.
There are various possible means for this alternate supply, but the one shown in FIG. 2 uses a slide valve 13 that can be switched by intermittent reciprocating movement of the piston 12 of the air cylinder 11. In other words, when the slide valve 13 is in the state shown by the solid line (the state in which it moves to the right), the supply path 8 is connected to the supply port 10 through the oblique hole 14 and can supply only the raw material A, and the slide valve 13 is When displaced to the position shown by the imaginary line (leftward position), only the supply path 9 is connected to the supply port 10 through the diagonal hole 15.
, and only raw material B can be supplied.

A mandrel 16 is located in the center of the crosshead 2, and an air pin 17 passes through the center so that air for blow molding can be supplied from above.

Reference numeral 18 denotes a stagnation area on the outer periphery of the mandrel, and in particular, the corner portion 18' is a place where stagnation occurs even when the raw material is changed, and contamination with a different type of raw material to be extruded next occurs. 19 is a discharge port of the parison 20. 21,
Reference numeral 22 denotes a mating mold, in which a cavity 24 is formed, in which, for example, a vehicle armrest 23 as shown in FIG. 4 can be formed. and air pin 17
The tip is inserted into the cavity 24 from above.

To carry out the present invention using such an apparatus, first, fine grains of glossy dark brown high-density polyethylene A are supplied to tank 6, and dull, light brown low-density polyethylene B is supplied to tank 7. supplying fine grains of
The slide valve 13 is alternately and intermittently switched, and the screw 3 of the extrusion device 1 sequentially transfers the material from the inlet to the outlet, bringing it into a molten state, and transferring it to the retention area 18 of the crosshead 2. At this time, the raw materials were switched by chance, and the molten raw material that had stagnated in the corner 18' was appropriately mixed into the next molten raw material.
It descends around the mandrel while making a striped pattern appear, and is extruded from the discharge port 19 as a parison 20. At this time, when the molds 21 and 22 are closed as shown in FIG. 1 and air is blown into the interior through the air pin 17, the parison 20 expands to fill the cavity 24. When the molds 21 and 22 are opened after cooling, the molds 21 and 22 are opened as shown in FIG. The armrest 23 is taken out. The appearance of this armrest has a so-called woodgrain texture in which glossy dark brown layers 24 and dull light brown layers 25 exist alternately and irregularly, and the wood grain is dense near the area 26 where the blow ratio is low. A product with an elegant appearance that varies in density can be obtained.

FIG. 5 shows the external appearance of an assist trap type armrest 27 obtained by the method of the present invention, in which substantially the same wood grain as the armrest 23 appears on the surface.
In addition, hollow wood-grain-like synthetic resin products with an irregular three-dimensional structure can be applied to a variety of other products.

FIG. 3 shows another switching supply device for two types of raw materials A and B. This uses a rotary valve 28, and in the illustrated state, a through hole 29 connects the supply path 8 and the supply port 10, and only raw material A can be supplied, but if the rotary valve 28 is rotated by 180 degrees, Since the through hole 30 communicates only the supply path 9 and the supply port 10, only the raw material B is supplied.

Although the combination of raw material A and raw material B can be freely selected, in addition to the raw materials explained in the above examples, combinations of hard vinyl chloride and soft vinyl chloride are suitable.

As mentioned above, the molding temperature does not require a very high temperature, and good results can be obtained by setting the molding temperature to 0°C to -10°C based on the melting point of the higher one of raw materials A and B.

〔Effect of the invention〕

As explained above, according to this invention,
The structure is that raw materials A and B of different shades of tea are alternately supplied to the supply port of a crosshead type extruder, A and B are alternately transferred and melted by a screw, and the molten raw materials A or B retained in the crosshead are transferred to the next extruder. The parison is mixed into the extruded raw materials B or A of different types to be extruded, and the parison is extruded while creating a vertical striped pattern, and the parison is blow-molded using a mold having a cavity with an irregular three-dimensional structure with a large change in blow ratio. Unlike injection molding, raw material A can be molded at a relatively low temperature.
When B and B are mixed together, the boundaries between each layer are not blurred and a wood-grain appearance is obtained.Also, since the blow ratio of each part in the irregular three-dimensional structure of the cavity is different, the parison discharged from the discharge port is The monotonous striped pattern is blown and expanded, resulting in uneven density, making it easy to continuously obtain hollow products with the appearance of real wood grain, as well as improving the feeding device by utilizing existing machinery. It has the effect of being able to be carried out with only one person.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view of an apparatus suitable for carrying out the present invention, FIG. 2 is an enlarged longitudinal sectional side view of a feeding device,
FIG. 3 is an enlarged longitudinal sectional side view showing another embodiment of the feeding device, FIG. 4 is a perspective view of an armrest obtained by implementing the present invention, and FIG. 5 is an assist grip type obtained by the present invention. FIG. 3 is a plan view of the armrest of FIG. 1... Crosshead type extruder, 10... Supply port, 3... Screw, 2... Crosshead, 2
0...Parison, 24...Cavity, 21,2
2...Mold.

Claims (1)

[Claims] 1 Raw materials A and B of different shades of tea are alternately supplied to the supply port of a crosshead type extruder, A and B are alternately transferred and melted by a screw, and the molten raw materials A or B retained in the crosshead are then extruded. The parison is extruded while forming a vertical striped pattern while being mixed into different types of molten raw materials B or A, and blow molding is performed using a mold having a cavity with an irregular three-dimensional structure with a large change in blow ratio. A method for manufacturing a wood-grain-like hollow body, characterized in that the interval between stripes corresponding to wood grains is varied in density depending on the blow ratio.