Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – Deforming the surface only
Reexamination Certificate
2002-07-26
2004-11-02
Swiatek, Robert P. (Department: 3643)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
Deforming the surface only
C264S154000, C264S163000
Reexamination Certificate
active
06811735
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
The present application claims priority to Japanese Patent Applications No. 2001-228480 filed Jul. 27, 2001, No. 2001-346096 filed Nov. 12, 2001, and, No. 2001-361399 filed Nov. 27, 2001, the entirety of each is hereby incorporated into the present application by this reference.
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing by molding an automobile interior article body (or a hard resin body) in which an automobile interior article having a cover portion being developed from which an airbag inflates is integrally molded of a hard resin material.
The invention will be described hereinafter mainly in connection with an instrument panel (hereafter abbreviated to “panel”) having a cover portion for an airbag. However, the invention can also be applied to cover portions for airbags for side doors, pillars and front/back seats.
In the so-called “hard panel” (the usual injection-molded panel), the body of which is molded of a hard resin (e.g., PPF), a bag covering member formed at the pop-out port of the passenger's seat airbag is molded in the prior art separately from the panel body. Therefore, a gap or abrupt shift in the surface is easily formed between the bag covering member and the panel body so that restrictions must be placed on the design, increasing the number of assembling steps.
Therefore, there has been proposed (as referred to FIGS. 4 and 5 of Unexamined Published Japanese Patent Application No. 71924/2000) a hard panel which is constructed to comprise: a hard resin body (or a panel body) having an integrally molded cover portion; and a soft resin connector (or an airbag supporting assembly) jointed to the rear side of the cover portion and assembled with an airbag module.
Moreover, the cover portion of the panel or the hard resin body is required to have grooves or notches to be broken, so that the cover may be broken when the airbag is activated.
These grooves or notches are formed by a high-frequency welder or a laser working after the panel body is injection-molded. However, the formations of the grooves or notches are done after the molding so that the number of steps increases. Moreover, it is difficult to control the breaking positions and depths, and costs rise as a result.
Therefore, a technique for forming the broken groove portions (or the notch portions) by stamping a groove forming projection just after the end of injecting has been proposed (in Unexamined Published Japanese Patent Applications No. 268205/1996, No. 254919/1991 et al) in pads for steering wheels (molding of a soft resin material).
In case this technique is applied to a hard panel (or an automobile interior article body) made of a hard resin material, however, it has been found that extrusion marks due to the pushing of the groove forming projection (or the groove forming block) appear on the surface of the molding (design face), a problem which does not occur in the case of soft resin material. It is hypothesized that the pushing pressure is harder for hard resin material to absorb than the soft resin material.
SUMMARY OF THE INVENTION
In view of the foregoing background, the present invention has an object to provide a method for die-molding an automobile interior article body to which a cover portion being developed from which an airbag inflates is integrally molded of a hard resin material and in which no extrusion marks caused by pushing of the tear-line forming projection appear on the surface side.
In order to solve the aforementioned problem, we have keenly pursued promising developments and have found that the problem can be solved if the stamping of the tear lines is done during the time between just after the material filling (or injection) to the end of filling, and to conceive a method for manufacturing the above automobile interior article having the construction as described below.
According to a mode of the invention, there is provided a method for die-molding with a hard resin material an automobile interior article incorporating integrally a cover portion being developed from which an airbag inflates, wherein the cover portion is also molded of a hard resin material integrally with the other portions, and wherein a tear line forming block having continuous or discontinuous tear line forming protrusions corresponding to the tear lines for the cover portion is moved forward at the molding step during the time between just after the start of mold filling to the end of filling to form the tear lines.
While the molding material is being filled, its fluidity is so excellent that extrusion marks therefore hardly appear at all in the design surface.
This effect is attained more reliably if the forward movement of the tear line forming block is done in one half of the time taken for filling of the molding material.
It is usual that the forward movement of the tear line forming block is done in {fraction (1/10)} to ½ of the mold filling time.
Alternatively, at the time of the forward movement of the tear line forming block, the temperature of the mold at its face forming the outer side of the molding, opposite to the tear line forming block, may be higher than that of the tear line forming block. The cooling and hardening from the outer side can thus be suppressed to reduce the resistance of the material to the stamping during tear line forming.
More specifically, the molding temperature of the mold at its face forming the outer side of the molding opposite to the tear line forming block is kept between the thermal deforming temperature (ASTMD648: 455 k Pa) and the melting temperature till just after the completion of the forward movement of the tear line forming block.
In this construction, moreover, it is desired that the backward movement of the tear line forming block is completed before the mold opening. If the backward movement of the tear line forming block is done after the mold is opened, the drawing resistance of the tear line forming projection is so high that the surface appearance will probably be affected.
In this construction, it is desired that the backward movement of the tear line forming block of the tear line forming projections is done at a plurality of steps. In this way the shape of the tear line forming holes is stabilized. If the tear line forming block is moved backward at an early time, for example in one step while pressure is being applied, the material at the opening of the holes forming the tear line still has fluidity so that there is a possibility it will flow in the direction to close the opening of the tear line forming holes and set in that shape. At a late time just before the mold opening or just before the completion of the cooling time, on the other hand, the drawing resistance of the tear line forming projection is lower than the aforementioned one but may cause a similar problem.
Among the steps of the backward movement of the tear line forming block, the first one usually is during the mold pressurizing time and the last one during the mold cooling time. It is desired that the first and last steps of the backward movement of the tear line forming block are done in {fraction (1/10)} to ½ of the mold pressurizing time and for ½ to {fraction (9/10)} of the mold cooling time, respectively. Moreover, if the backward movement of the tear line forming block is done in two steps, the backward stroke of the first step is {fraction (1/10)} to ½ of the whole stroke.
In the individual constructions thus far described, moreover, it is desired the tear line forming projections are made of a set of conical or frustoconical pins. The material flow is smoothed, and the leading ends of the individual pin holes to be formed by the tear line forming projection are tapered to facilitate the stress concentration and to stabilize the cover portion expandability.
Another object of the invention is to provide a surface portion thermal molding method for thermally molding (or vacuum molding) the surface portion of an automobile interior article having a
Furuta Kenichi
Nagano Akiyoshi
Shigeno Kazumichi
Sugiyama Kenji
Ueno Shigehiro
Swiatek Robert P.
Toyoda Gosei
LandOfFree
Method for manufacturing automobile interior article does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for manufacturing automobile interior article, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for manufacturing automobile interior article will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3286801