Stock material or miscellaneous articles – Hollow or container type article
Reexamination Certificate
2002-11-21
2004-02-10
Pyon, Harold (Department: 1772)
Stock material or miscellaneous articles
Hollow or container type article
C428S035700, C428S188000, C428S133000, C296S205000, C264S512000, C264S531000, C220S651000, C220S652000, C220S653000
Reexamination Certificate
active
06689435
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to thermoplastic hollow articles that are excellent in rigidity and impact absorption qualities, as well as to the manufacturing process for producing the hollow articles.
2. Background Art
Hollow articles are well known in the art and used in a variety of industries and applications. These plastic hollow articles are lightweight, strong, and relatively inexpensive to manufacture using injection or blow molding techniques.
There are numerous examples of products that employ hollow articles, such as ducts, panels, or housings for electronics, appliances, automobiles, and house wares. In many homes these hollow articles are found in walls, partitions, and panels, such as entrance doors, and indoor air conditioning ducts. Furniture is also manufactured with hollow structures, and includes top plates of desk, partition panels, and bookshelf panels.
In the appliance sector, housings of some of the components are hollow such as used for refrigerators and televisions. The hollow articles are also used in office equipment, such as the housings of copy machines, facsimile machines and computer peripherals.
Panels and ducts of dwelling facilities, furniture panel, housing of electric household appliances, housing of office equipment and automotive parts are often required to have a high rigidity. Hollow articles used in such applications are manufactured in integral structures combining a first wall and a second wall by means of a rib linking them mutually within a hollow space. In cases where the appearance is important on both face and back surfaces, a structure termed an “inner rib” is employed. Thus, the first wall and the second wall are projected, in blow molding, until a part of the second wall contacts with a wall to be linked integrally within the hollow space there between.
The automobile industry uses hollow articles because of the mechanical properties and weight characteristics. Automotive parts include console box lid, hood, door panel, and air conditioning duct. For example, in order to assure the rigidity as a product or to protect the crew from impact of collision, an automotive roof side duct is disposed near both sides of ceiling as explained in Japanese Patent Application Laid-Open No. 2000-43541.
The automobile industry is particularly interested in increasing the safety of the vehicles, and at a minimum, complying with the certain safety guidelines. According to the Federal Motor Vehicle Safety Standards (FMVSS), the hollow articles must have a minimum level of impact absorption. The guidelines are established under the Department of Transportation by the National Highway Traffic Safety Administration. There are a number of guidelines and requirements, including FMVSS 201 that addresses occupant protection in interior impact. There are other guidelines that describe related topics such as resistance to roof crushing. Head injuries are calculated according to a ‘heading injury criteria’ (HIC) that is obtained from the deceleration of the head during the duration of the impact. These federal standards must be satisfied in order for vehicle to enter the U.S. market. And, these regulations are continuously being updated as new innovations and features result in improved safety characteristics.
There are many studies that demonstrate that significant head injuries and trauma occur when the driver or passengers head strikes the interior roof and side panels. A rigid interior wall offers little impact absorbing qualities when struck by a human head. There are a number of techniques used to impart some shock absorbing qualities into the roof and interior panels, but the strict government standards continue to increase and demand greater safety thresholds. The use of ceiling air bags and structural modifications to the support elements are designed to address the impact absorbing qualities, however there are issues such as cost and manufacturability that limit the wide-spread use of such features.
As shown in prior art
FIG. 11
, the inner rib of a roof side duct is integrally formed by blow molding, wherein an inside wall
101
facing a ceiling interior member
107
and an outside wall
102
facing an inner panel
106
of car body confront each other. A flat impact absorbing rib
103
is disposed along the longitudinal direction in a space
110
between the inside wall
101
and outside wall
102
. A general manufacturing method of this roof side duct is explained by referring to
FIGS. 12
a
,
12
b
, and FIG.
13
.
Prior art
FIG. 12
a
shows a molten parison
300
being poured into opened split molds
201
,
202
, and then the molds are closed. Next, a rib forming plate
203
is projected toward the second mold
202
, and a neck
303
is formed in the area of first wall
301
of the parison, and its leading end is pressed tightly to the area of second wall
302
. Then, as shown in
FIG. 12
a
, the rib forming plate
203
is pulled in, the pressurized air is introduced into the parison
300
, and is inflated into a shape along the cavity by the internal pressure of the pressurized air, and the neck
303
is pressed and deformed in the direction of the arrows, while confronting walls are fused integrally, so that an impact absorbing rib
304
is formed.
According to the prior art, as shown in
FIG. 13
, when pulling in the rib forming plate
203
, after projecting the rib forming plate and forming a neck at first wall side of the parison, the neck is dragged in the backward direction of the rib forming plate
203
, or is elongated by the blow pressure in the blow process, and the wall thickness and width of the flat rib formed as the confronting walls of the neck are compressed from both sides by internal pressure of the pressurized air are decreased. Thus, at portion
305
the inner rib is reduced in wall width and the shape, and the dimensions and wall thickness of the flat rib are not uniform on the whole. As a result, the rigidity and other mechanical strength of the impact absorbing rib
304
are lowered, and the duct having sufficient impact absorbing performance is lessened. Furthermore, the varying thickness of the inner rib results in some inconsistency in impact absorbing qualities. In the described application, such a product may result in inadequate protection in the event of a collision. Other applications may result in improper rigidity and strength and at the very least, inconsistency in the produced hollow article.
What is needed is a hollow article with a rib of uniform shape, dimensions and wall width. The rib should have excellent mechanical strength and properties. In one embodiment, such as automotive, the hollow article with the rib should have impact absorbing qualities to protect the driver and passengers. The manufacturing method for such an improved hollow article should be cost-effective and have a low defect rate.
SUMMARY OF THE INVENTION
The invention is devised in the light of the problems of the prior art described herein. The present invention is a hollow article having an impact absorbing rib uniform in shape, dimensions and wall width on the whole, especially free from reduction of wall width of the inner rib, yet possessing proper rigidity and mechanical strength, and excellent impact absorbing performance.
Another aspect of the invention is to ensure compliance with the FMVSS 201 regulations addressing interior head injury criteria. According to FMVSS 201, the interior of the vehicle in the U.S marketplace must have a head injury criteria (HIC) of less than 1000. The value is determined by striking a dummy head of a certain mass into the regions of the vehicle interior at a certain speed and measuring the shock value. The present invention results in an article that is well within the federal guidelines. In addition, present invention has a greater consistency and repeatability as compared to prior art products that have a higher rate of failure of compliance. The prior art components are generally unable to satisfy the HIC standards, and there
Egan Brian P.
Kyoraku Co. LTD
Maine & Asmus
Pyon Harold
LandOfFree
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