JPS5872789A - Cylindrical article which is made of synthetic resin and has bellow section - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin cylindrical object, and particularly to a cylindrical object having a bellows part in a part thereof and whose length can be adjusted and bent.

Currently, products such as washing machine hoses and drinking straws are made of synthetic resin cylinders that can be freely bent in three dimensions or expanded and contracted to make them easier to handle during use. The product is widely used. In particular, the hose joints of washing machines have at least three bellows parts to improve flexibility. The elasticity makes piping much easier. The demand for this will continue to increase in the future. For example, when storing pharmaceutical powder, it is necessary to shrink the pharmaceutical powder in advance, store it in this state, stretch it out, and add water when drinking or using it. Its use is being considered in fields such as bringing about reductions in freight costs by using it.

Conventionally, such a synthetic resin cylinder 2-shaped article having a bellows part is usually produced by extrusion molding, cooling, and then shaping by means such as spiral cutting in the secondary processing step. It had been.

However, with this manufacturing method, the occurrence of pinholes during molding cannot be avoided, and molding by blow molding has gradually become popular.

Blow molding does not require inspection for pinholes due to its manufacturing method, and therefore has much improved quality compared to conventional methods. is made so that the shape of the folds forms an isosceles triangular cross section when extended, so that the projection length formula onto the cylindrical motion axis is made to have the same length on the two sides that sandwich the apex angle of the chevron. 〇 Generally, the length adjustment by the bellows part is done by stretching the bellows part, but if this stretching can be done too easily, it is not preferable because the cylindrical object lacks elasticity.On the other hand,
Another problem is that a considerable amount of force is required for expansion.

This is greatly influenced by the properties of the synthetic resin material used, and in order to alleviate this effect, it is desirable to use a resin with repulsive force, such as polyethylene, which has been conventionally used for materials such as hoses. ing.

However, even if a repulsive resin is used to mold a cylindrical object with a bellows part from polyethylene resin, etc.,
As mentioned above, if the lengths of the two sides sandwiching the apex angle of the protrusion are the same, the direction of the stress during tension will be in equilibrium and will not act effectively, so a considerable force will still be required for extension. ,
Expansion, contraction.

Otherwise, damage could not be avoided due to repeated bending in different directions.

The present invention has been developed in response to such a fact, and in order to eliminate this defect, the role of the folds in the bellows section has been carefully studied.As a result, the stress is reduced by making the folds have an unequal triangular cross section instead of an isosceles triangular cross section. It has been discovered that it is possible to obtain a cylindrical molded product that has a V that can be used, has hinge properties at the top and has strength for rotation, and is easily expandable.

That is, the present invention is characterized in that the projection lengths of the two surfaces sandwiching the apex angles of the folds in a portion of the bellows 4 on the central axis of the cylindrical molded product are made different, and the lengths are unequal. , the top end of the protrusion on the short side or the inwardly bent top end is on a plane perpendicular to the axis of the cylindrical molded product from the top end of the protrusion,
Alternatively, a bent portion having a doglegged or inverted doglegged cross section is formed at least slightly closer to the long side.

Hereinafter, specific embodiments of the present invention will be further explained based on the accompanying drawings.

FIG. 1 shows an example of a synthetic resin cylindrical article according to the present invention,
FIGS. 2 and 3 are partially enlarged views.

In these figures, (1) shows a cylindrical object, and (2) shows a partially formed bellows part, which are usually molded all at once by blow molding of synthetic resin.

Normally, the number of bellows parts (2) is selected appropriately depending on the purpose of use, and one or more pieces are molded. However, the diameter of the cylindrical molded product varies widely, and the number of bellows parts (2) and the number of folds also vary. There are no restrictions whatsoever.

FIGS. 2 and 3 are enlarged views of the bellows portion (2) 5- in the above configuration, and clarify the features of the present invention.

That is, as shown in the explanatory diagram of FIG. 3, in the present invention,
A cylindrical molded product (1) with two surfaces (Sl) and (S2) sandwiching the apex angle of the chevron-shaped protrusion (3) of each fold constituting the bellows part (2).
The projected lengths C1, ) and <i2> of Buttl>
t2 It's gone.

In this case, there is no particular limit to the ratio of t and t2, but the preferred ratio is 4=V4~%, where t is l,
Most preferred is FX, %.

Furthermore, the top end (4) of the chevron-shaped protrusion (3) of the front fold part
), the bent portion (
5) is formed, and the bent top end of this bent part (5) is on a plane perpendicular to the central axis of the cylindrical molded part (11) or longer than the top end (4) of the projection part (3). It enters the side and forms a bent part (5) with a doglegged or inverted doglegged cross section in the armpit.

Note that the 6-position in the radial direction of the cylindrical molding at the top end of the bending part (5) is not sufficient for the desired stretching and bending operation if it is too much in the center axis band, and the top end of the chevron-shaped protrusion (3) An appropriate range is within y from the top end side between the outer diameter where the troughs are connected and the inner diameter where the troughs are connected.

Furthermore, when this chevron-shaped protrusion (3) is V-formed by blow molding, the wall thickness of the covering part is not necessarily the same due to the mold, as shown in Fig. 2. The wall becomes thinner at the top of the chevron-shaped protrusion. On the other hand, the troughs have an appropriate curvature, and as a result, both of them provide a hinge property, and provide a good force for orientation when compressing uniformly and contracting and elongating the folds.

Therefore, when stretching the fold, the bending part (5
) and unevenly spaced folds, the elongation stress moves out of equilibrium and cooperates with each other, making it possible to easily elongate using stress, compared to the conventional mold shape with equal pitches. , it can be expanded with much less force, and it can also be contracted.

Furthermore, due to the stress effect during expansion and contraction, the bending in the three-dimensional direction becomes easier, and the tendency for excessive force to be applied to the entire molded article 7- is reduced.

Therefore, in the past, repellent resin was required in order to improve extensibility, but this is not necessary and the range of applicable resin materials is wider, expanding the scope of molding technology. Contribute to

Due to its extensibility and bendability, the cylindrical molded product obtained by the present invention is not limited to conventional hoses and straws, but can also be easily used to develop capsule products that are at the forefront of the times, such as storage tubes for drug powder. It should be noted that it is possible to expand into

As described above, the cylindrical article of the present invention changes the chevron-shaped protrusions of each fold of the bellows part of the cylindrical molded product, makes the pitches unequal, and penetrates inside the chevron-shaped protrusions on the short side portion slightly inward. It has a structure with bent parts, and the unequal pitches not only reduce the pull-out stress during stretching and make it easier to stretch, but also the bent parts near the apex allow for further stretching, reducing the stretching action during time. It has the advantage of increasing the hinge properties and effectively playing the role of the bellows of the cylindrical molded material in the bellows part.Furthermore, it expands the range of application of the resin material used, and eliminates pinholes caused by blow molding. In conjunction with the total elimination of cylindrical materials, the use of various synthetic resin cylinders with bellows parts has been expanded, allowing them to be used in various types of containers outside of distribution pipes, and their practical utility is highly anticipated in the future. It is.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view showing an example of a cylindrical molded product having a bellows portion according to the present invention, Fig. 2 is a partially enlarged view of Fig. 1A, and Fig. 3 is a partially detailed explanatory view of the structure. It is. (1)...A cylindrical object, (2)...A bellows part. (3)...A chevron-shaped protrusion, (4)...Apex of the protrusion. (5)...Bent part, (S,)...Long side part. (S2)...Short surface part. 9-

Claims (1)

[Scope of Claims] / In the bellows part of a synthetic resin cylindrical molded product having a bellows part, length adjustable, and freely bendable, the apex angle of the chevron-shaped protrusion of the pleats constituting the bellows part The projection lengths on the axis of the two sandwiched sides of the cylindrical molded product are unequal, and the bent top end is formed into a cylindrical shape slightly inwardly from the top end of the projection on the short side. Synthetic resin cylinder having a bellows section characterized by forming a bent part with a doglegged or inverted doglegged cross section located on a plane perpendicular to the center axis of the object or at least closer to the long side. something like that. 2. A synthetic resin cylindrical article having a bellows portion as claimed in claim 1, characterized by a ratio of the projected lengths of two surfaces sandwiching the apex angle of the chevron-shaped protrusion onto the axis of the cylindrical molded article. . 3. A cylindrical article made of synthetic resin having a bellows portion according to claim 1 or 2, in which the top end of the chevron-shaped protrusion of the folds is thinned. 1-