Note: Descriptions are shown in the official language in which they were submitted.
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BLOW-MOLDED BOTTLE-SHAPED CONTAINER
MADE OF SYNTHETIC RESIN
The present invention relates to a biaxially blow-molded
bottle-shaped container made of synthetic resin, and more
particularly, to a construction of portions which contact with
each other when said bottle-shaped containers are stood upright
to be adjacent to each other.
Biaxially blow-molded bottle-shaped containers made of
synthetic resin (hereinafter referred to as "blow-molded bottle-
shaped containers") such as polyethylene terephthalate resin are
typically each filled with contents, sealed by a cap, applied
with a label and packed in a corrugated card-board box by a
packer, while being transported.
Most of such blow-molded bottle-shaped containers are
relatively large. Accordingly, their weight when filled
is considerably heavy.
It is desired that a quantity of synthetic resin material
required to mold a bottle-shaped container be as small as
possible to form a bottle-shaped container at lower cost.
Accordingly, the blow-molded bottle-shaped container is molded by
sufficiently orienting a parison. Accordingly, a wall thickness
of a body of the bottle-shaped container which forms a main
portion of a content receiving portion is very thin.
In a blow-molded bottle-shaped container molded by
sufficiently orienting a parison, there cannot always be obtained
an uprightness with high accuracy (when a bottle-shaped container
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is stood upright on a horizontal surface, a larger angle of
inclination with respect to a vertical line of a center axis of
the container results in poor uprightness of the container)due
to an internal strain or the like caused by orientation, and the
bottle-shaped container is stood upright in a slightly inclined
attitude. Particularly, in the case of a blow-molded bottle-shaped
container molded as a heat-resistant bottle-shaped container, the
inferiority of the uprightness tends to increase.
Since the blow-molded bottle-shaped container is heavy when
it is filled with a content liquid, if the container is slidably
moved even on a smooth plane, a considerable sliding resistance
occurs. Since the wall thickness of the body which forms a main
portion of a bottle-shaped container is thin, when a strong
lateral load is applied to the body, it becomes easily depressed
and deformed. Since the uprightness of the bottle-shaped
container is not good, when a number of blow-molded bottle-shaped
containers are arranged to be adjacent to each other in an
upright attitude, portions of the body contacted with the
adjacent blow-molded bottle-shaped containers are not constant.
Where the bottle-shaped containers are slidably conveyed,
the sliding resistance produced between the conveying surface and
the blow-molded bottle-shaped container is high. When a number of
blow-molded bottle-shaped containers arranged to be adjacent to
each other along a constant conveying line are pressed from the
back and slidably conveyed on the conveying surface, a great
lateral load acts on the body contacted with the adjacent blow-
molded bottle-shaped container. The central portion of the body
is not always sufficient in mechanical strength with respect to
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the lateral load. When the high lateral load acts on the central
portion of the body, there gives rise to an occurrence of
depressed deformation in the central portion of the body.
Furthermore, since the uprightness of the blow-molded bottle-
shaped containers is not good, when a plurality of containers
placed to be adjacent to each other are pressed and slidably
conveyed, the uprightness of each of the blow-molded bottle-
shaped containers becomes unstable. Accordingly, an accurate
detection of the position of a bottle-shaped container becomes
impossible. In some cases, bottle-shaped containers being
conveyed fall so that operation should be discontinued.
In a conventional blow-molded bottle-shaped container of
this kind,in order to overcome the aforementioned inconveniences,
a diameter of a lower portion contacted with a leg is made
sufficiently larger than other portions of the body so that when
the blow-molded bottle-shaped containers are arranged to be
adjacent to each other, the lower end portions of the bodies
contact with each other. Since the lower end of the body having a
large diameter is close to the leg, the lower end of the body is of
relatively high mechanical strength. The lower end of the body
receives a lateral load exerted when a plurality of bottle-shaped
containers are slidably conveyed. Since the lower end of the body
is positioned at the lower end of the blow-molded bottle-shaped
container, a moment acting on a blow-molded bottle-
shaped container is reduced due to the sliding resistance and the
pressing conveying force when the plurality of bottle-shaped
containers are slidably conveyed.
As described above, in prior art, the lower end of the body
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is made to have a large diameter, and the blow-molded bottle-
shaped containers stood upright and arranged to be adjacent to
each other are made to contact with each other at their lower
ends of the bodies, whereby a number of blow-molded bottle-shaped
containers can be slidably conveyed in an upright and stabilized
attitude. However, recently, many blow-molded bottle-shaped
containers have been subjected to processing such as filling with
liquids per unit time.-Therefore, the lateral load acting on the
lower end of the body when the containers upright and adjacent to
each other are pressed and slidably conveyed becomes more
powerful. Accordingly, the mechanical durability of the lower end
of the body with respect to the lateral load was required to be
increased.
The simplest countermeasure to the aforesaid demand is to
sufficiently increase a wall thickness of the lower end of the
body. However, when the wall thickness of the lower portion of
the body is increased, the quantity of an expensive synthetic resin
material required to mold a blow-molded bottle-shaped container
increases by said increased portion, resulting in an increase in
price of the blow-molded bottle-shaped container. Therefore, this
countermeasure is not desirable.
The countermeasure considered to be most effective or prior
art which fulfills the aforesaid demand is to control a wall
thickness of the container when a blow-molded bottle-shaped
container is biaxial blow-molded so that the wall thickness of
the lower end of the body is made larger than the wall thickness
of other body portions. This conventional means is intended to
increase the wall thickness of the lower end of the body to
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thereby increase the mechanical strength of the lower portion of
the body. The conventional means can obtain an effect of
increasing the mechanical strength of the lower portion of the
body. However, the wall thickness of the other portions of the
body is to be reduced by a portion having increased wall
thickness of the lower portion of the body. Because of this,
there gives rise to an important problem of considerably lowering
fundamental functions of the blow-molded bottle-like container as
a container, such as durability of the body with respect to the
lateral load, durability of other body portions with respect to
the lateral load, shape stability of the body with respect to a
gripping force during handling, constantness and stability of
pressure reduction absorbing deformation in a heat resistant
bottle-shaped container, and the like.
A principal object of the present invention is to
considerably increase the mechanical strength with respect to a
lateral load at a lower portion of a body of a container without
reducing a wall thickness of other portions of the body and
without increasing the amount of synthetic resin material
required to mold a bottle-shaped container.
The present invention provides a biaxially blow-molded
bottle-shaped container having a body with a plurality of
longitudinally-extending absorbing panel portions uniformly
disposed about a circumference of the body and a lower end
of the body between the body and a leg of the body.
Two circumferential ribs are provided and externally
swelled on the lower end of the body thereby providing a
largest diameter of the container; a diameter of the lower
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end of the body being smaller than the largest diameter.
Upper and lower portions of those circumferential ribs
comprise rib walls in a form of a tapered wall, and the
circumferential ribs each have sufficient vertical height
such that, when pressed against an adjacent container, at
least a portion of the vertical height of at least one of the
circumferential ribs is the only contact with the adjacent
container, even if the adjacent container is slightly
inclined and is a similarly-shaped article.
Preferably, a circumferential recessed groove having a
small width is provided between the circumferential ribs.
In a particularly preferred embodiment a diameter of the
upper end of the body is equal to that of the lower end of
the body, a circumferential rib is provided and externally
swelled on the upper end of the body, and upper and lower
portions of the circumferential rib comprise rib walls in the
form of a tapered wall. In this embodiment at least two
circumferential ribs may be provided in parallel on the upper
end of the body, and a circumferential recessed groove having
a small width is provided between the circumferential ribs.
A "main portion of a body" refers to a portion which has
a function to receive and hold a content liquid. For
example, in the case of a heat-resistant bottle-shaped
container, the "main portion of the body" is a body portion
formed with an absorbing panel wall for absorbing reduced-
pressure in the container. In a general concept, the "main
portion of the body" is a portion having a substantially
uniform diameter, other than a shoulder and a bottom
including the leg.
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The present invention is not limited to providing a
single circumferential rib. A circumferential recessed groove
having a small groove width (a sufficiently smaller groove width
than a longitudinal width of a circumferential rib) may be
interposed between circumferential ribs so that two or more
circumferential ribs are disposed in parallel.
The circumferential rib is inflated from the lower end of
the body. Accordingly, the circumferential ribs of adjacent
containers contact with each other so that the blow-molded
bottle-shaped containers are stood upright adjacent to each
other. A pressing force for press-conveyance acting on an
upstream blow-molded bottle-shaped contAiner to an adjacent blow-
molded bottle-shaped container during slidable conveyance of
blow-molded bottle-shaped containers directly acts on the
circumferential rib.
Since the circumferential rib adapted to directly receive
the pressing force from the adjacent blow-molded bottle-shaped
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container is designed to have upper and lower rib walls in the
form of a tapered wall, rib walls act as a reinforcing rib.
Accordingly, the pressing force exerted from the adjacent blow-
molded bottle-shaped container is received by the sufficient
mechanical strength to considerably increase the mechanical
durability with respect to the lateral load of the whole lower
end of the body.
In the case where two or more circumferential ribs are
disposed in parallel, the number of rib walls serving as the
reinforcing rib increases, and the mechanical durability with
respect to the lateral load at the lower end of the body can be
increased.
The reason why the width of the circumferential recessed
groove positioned between the circumferential ribs where the
plurality of circumferential ribs are disposed in parallel is to
prevent a circumferential rib of a blow-molded bottle-shaped
container from being moved onto a circumferential rib of the
adjacent blow-molded bottle-shaped container to greatly incline
the other blow-molded bottle-shaped container during conveyance.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a front view of a polyethylene terephthalate
bottle-shaped container applied to work out first and second
embodiments of the present invention;
Fig. 2 is a view showing a contour line of essential parts
of the first embodiment of the present invention in an enlarged
longitudinal section;
Fig. 3 is a view showing a contour line of essential parts
of the second embodiment of the present invention in an enlarged
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wall.
In Fig. 2, the broken line indicates a contour line of prior
art. The circumferential rib 5 of the present invention is not
formed as a part of a curved surface smoothly continuous to the
outer circumferential surface of the lower end 4 of the body as
in prior art. In the circumferential rib 5 of the present
invention, the largest diameter portion is the
circumferential rib 5, and the diameter of portions of the lower
end 4 other than the circumferential rib 5 is redu-ced. The
circumferential rib 5 in the first embodiment of the present
invention has a relative large height. The reason why the
circumferential rib 5 is formed by leaving the largest diameter
portion of the lower end 4 of the body in prior art is to prevent
the diameter of the lower portion 4 of the body from being
increased more than as needed by the provision of the
circumferential rib 5. The reason why the height of the
circumferential rib 5 is relatively large is because the pressed
adjacent containers 1 are always placed in contact with each other
at the circumferential ribs 5 even if the upright attitude is
slightly inclined.
In the first embodiment shown in Fig. 2, when a lateral load
of 5 Kg was applied to the container, a distortion of the lower
end 4 of the body in a radial direction was 1.20 mm. On the other
hand, when a lateral load of 5 Kg was applied or a container not
provided with the circumferential rib 5 at the lower end 4 of the
body, a distortion of the lower end 4 of the body in a radial
direction was 1.50 mm. According to the first embodiment of the
present invention, the distortion of the lower end 4 of the body
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in a radial direction can be considerably reduced and an
occurrence of buckling deformation can be completely eliminated.
Fig. 3 shows a second embodiment in which two
circumferential ribs 5 are provided in parallel. A height of each
circumferential rib 5 is smaller than that of the circumferential
rib 5 shown in Fig. 2. However, the sum of the height of both the
circumferential ribs 5 is larger than the height of the
circumferential rib in the first embodiment shown in Fig. 2.
The test for lateral load was conducted with respect to the
container in the second embodiment shown in Fig. 3 under the same
conditions as noted above. The distortion of the lower end 4 of
the body in a radial direction was 1.09 to 1.12 mm, and the
distortion can be further considerably reduced, and the
occurrence of the buckling deformation can be completely
eliminated.
The wall thickness of the lower end 4 controlled by the wall
thickness controlling means was 0.55 mm which is larger by 0.15
mm than that of the container 1 according to the present
invention. When the aforementioned lateral load test was
conducted with respect to this container, the distortion of the
lower end of the body in a radial direction was 1.13 mm, and thus
the container exhibits an excellent durability. However, as
previously mentioned, since the wall thickness of the body 2
other than the lower end 4 is small, the function of the
container as a whole was deteriorated.
Next, the third embodiment of the present invention will be
described. In the third embodiment, largest diameter portions of
a biaxially blow-molded bottle-shaped container made of synthetic
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resin include an upper end of a body which is an upper end of the
main portion of the body and a lower end of a body connecting
with a leg of the body. The diameter of the upper end of the body
is equal to that of the lower end of the body. Both the upper and
lower ends of the body are circumferentially provided with
circumferential ribs, respectively.
As described above, two circumferential ribs are provided on
the upper and lower portions of the body. Accordingly, the
pressing force for conveyance acting on a container from the
adjacent container is divided into upper and lower portions.
Because of this, a lateral load acting on a single
circumferential rib is reduced by half, and therefore, the
mechanical durability with respect to high lateral load of the
container as a whole is exhibited.
Circumferential ribs having the largest diameter are
positioned at both the upper and lower ends of the main portion
of the body. Accordingly, when containers are pressed and
placed to be adjacent to each other, the containers are pressed
and contacted with each other at both upper and lower
circumferential ribs. Portions of the body other than the
circumferential rib which are weak with respect to the lateral
load are positively prevented from being directly pressed so
that said portions are depressed and deformed. The adjacent
containers are pressed and contacted with each other at both the
upper and lower circumferential ribs. Accordingly, even if
there is a container which is poor in uprightness, the container
is supported at four points by adjacent containers, and
therefore, the upright attitude of each container during
pressing and slidable conveyance can be held at
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that of the circumferential rib 5 shown in Fig. 2. However, the
sum of the height of both the circumferential ribs 5 are larger
than that of the circumferential rib 5 in the third mode of
embodiment.
The lateral load test was conducted under the same
conditions as noted above with respect to the container according
to the fourth embodiment. The distortion of the lower end 4 of
the body in a radial direction was 0.54 to 0.56 mm. The
distortion can be further considerably reduced and the occurrence
of buckling deformation was completely eliminated.
The containers according to the present invention have the
construction as described above, and provide the following
effects.
The circumferential rib acts as a reinforcing rib.
Accordingly, the mechanical durability of the lower end of the
body (and the upper end of the body) with respect to the lateral
load can be considerably increased. Accordingly, the occurrence
of buckling deformation of the lower end of the body (and the
upper end of the body) when the container is pressed and slidably
conveyed can be prevented.
The circumferential rib is formed and externally swelled by
bending a wall having a substantially same wall thickness as the
lower end of the body (and the upper end of the body).
Accordingly, it is not necessary to increase the wall thickness
of the lower end of the body (and the upper end of the body)
partially to be projected. Accordingly, there occurs no
inconvenience that the wall thickness of the other portions of
the body of the container is reduced so as to lower the
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fundamental function of the container as a container. Since it is
not necessary that synthetic resin material be further added to
partially increase the wall thickness of the lower end of the
body (and the upper end of the body), the unit price of
containers is not increased due to an increase in material cost
for molding containers.
Since a container can be molded with a uniform wall
thickness of a body of the container, the wall thickness
controlling means is not required. Accordingly, the molding
operation for the container is simple.
Portions to be contacted with the adjacent container are
specified by the circumferential ribs. Accordingly, the mode of
transmission of the pressing force as the conveying force of the
containers is constant, whereby the upright attitude of the
containers pressed and slidably conveyed is stabilized.
