The present invention relates to an injection-molded product free from undercut in an as-molded state, to which a separate member can be easily fixed, and a bumper for an automobile as a use thereof.
An injection-molding die comprises a stationary die plate and a movable die plate for providing a cavity when closed, into which a molten resin is injected, and the parting of the movable die plate from the stationary die plate makes it possible to remove an injection-molded product having a shape corresponding to the cavity from the die. If the injection-molded product had undercut, the die would have a complicated structure to enable the removal of the injection-molded product. Accordingly, the injection-molded product preferably has a shape with as little undercut as possible.
For instance, some of injection-molded synthetic resin front bumpers for automobiles have openings in their bodies, to which grilles as separate members are fixed, but many of them have undercut in grille-fixing portions such as screw seats, etc. (see JP 2002-59794 A).
If there were no undercut in the grille-fixing portions of the front bumpers, the grille-fixing portions would likely be exposed from the edges of the openings of the front bumper bodies. Accordingly, the grille-fixing portions would be seen from front, providing poor appearance, and the grilles would have reduced opening area, leading to the reduction of an air flow to radiators.
JP 2000-108821 A discloses, as a mechanism of fixing a grille to a front bumper, a mechanism comprising projections extending rearward from an opening edge of the front bumper, through-holes formed in a flange of the grille for receiving the projections, and stoppers engageable with the projections penetrating the through-holes. The above mechanism further comprises a means for fixing the flange to the opening edge of the front bumper, and a mechanism for fixing the flange of the grille to the opening edge of the front bumper by screws. In the grille-fixing mechanism of JP 2000-108821 A, the grille-fixing portion is not exposed from the opening edge of the front bumper body, and the front bumper body is free from undercut.
However, the above fixing mechanism of JP 2000-108821 A needs the stoppers of the projections, and the flange-fixing means serve only to reduce the number of fasteners such as screws, etc., failing to fix the grille by themselves. In addition, the flange-screwing mechanism needs screws. Thus, the grille-fixing mechanism of JP 2000-108821 A needs a large number of fasteners, resulting in poor operation efficiency.
Accordingly, an object of the present invention is to provide an integral injection-molded product free from undercut in hooks for fixing a separate member in an as-molded state, the hooks being turned such that they can fix the separate member.
Another object of the present invention is to provide an integral bumper for an automobile free from undercut in hooks for fixing a grille in an as-molded state, the hooks being turned such that they can fix the grille.
As a result of intense research in view of the above objects, the inventors have found that because hooks for fixing a separate member (grille), which are connected via thin hinges to a body edge of an as-injection-molded product (bumper for an automobile), are substantially perpendicular to a parting direction of a die, the as-injection-molded product is free from undercut, and that the fixing operation of the separate member can be efficiently carried out by turning the hooks to a position at which they are substantially in parallel with the injection-molded product body and holding them at this position. The present invention has been accomplished by this finding.
Thus, the injection-molded product of the present invention comprises separate-member-fixing hooks each connected to an edge of its body via a thin hinge, the injection-molded product being formed by injecting a molten resin into a die comprising a pair of die plates, and the hooks extending from the edge substantially perpendicularly to a parting direction of the die in an as-molded state.
In a preferred embodiment of the present invention, each hook comprises a nail for being received in each hole of the separate member to fix the separate member, the nail projecting from the hook substantially in parallel with a parting direction of the die in an as-molded state.
In another preferred embodiment of the present invention, each hook comprises a hole for receiving each projection of the separate member to fix the separate member, the hole penetrating through the hook substantially in parallel with a parting direction of the die in an as-molded state.
In a further preferred embodiment of the present invention, the hook comprises one or more lateral projections engageable with holders formed in an edge of the body to keep the hook substantially in parallel with the body.
The bumper for an automobile according to the present invention comprises an opening for receiving a grille, and hooks for fixing the grille, which are connected to an edge of the opening via a thin hinge, the bumper being formed by injecting a molten resin into a die comprising a pair of die plates, and the hooks extending inward from an edge of the opening substantially perpendicularly to a parting direction of the die in an as-molded state.
In a further preferred embodiment of the present invention, the hook comprises a nail for being received in each hole of the grille to fix the grille, the nail projecting from the hook substantially in parallel with a parting direction of the die in an as-molded state.
In a further preferred embodiment of the present invention, the hook comprises a hole for receiving each projection of the grille, the hole penetrating through the hook substantially in parallel with a parting direction of the die in an as-molded state.
In a further preferred embodiment of the present invention, the hook comprises one or more lateral projections engageable with holders formed in an edge of the body to keep the hook substantially in parallel with the body by an elastic force.
a) is a partial, enlarged, perspective view showing the hook of the bumper of
b) is a partial, enlarged, perspective view showing the hook of the bumper of
A bumper for an automobile will be explained below in detail referring to the drawings as an example of the injection-molded product of the present invention.
[1] Bumper for Automobile
As shown in
When the hook 3 is rotated around the thin hinge 31, each lateral projection 32 having the above-mentioned shape is brought into contact with each side edge 12b. However, the rear end 33a of the slanting tip surface 33 of each lateral projection 32 would be in contact with each side edge 12b only in a small area if any, and each slanting tip surface 33 is in slanting contact with each side edge 12b. Accordingly, each lateral projection 32 of the hook 3 elastically deforms so easily that it passes each side edge 12b to the underlying step 13. Though the hook 3 tends to return to its original position by elasticity when it is freed, it is held substantially in parallel with the bumper body 11 because of engagement with an overhang 12c of each step 13.
The nail 3a of the hook 3, which projects toward the rear side of the bumper 1 in an as-molded state [
Thought not particularly limited, the number of the hooks 3 may usually be 5 to 7 along each upper and lower edge 12 of the bumper 1. Too many hooks 3 make the attachment of the grille 4 complicated, providing only excess fixing of the grille 4.
[2] Mechanism of Fixing Grille
As shown in
When the grille 4 is fixed to the bumper 1 shown in
[3] Method of Molding Bumper
In the as-injection-molded bumper 1, as shown in
Though the present invention has been explained referring to the drawings as described above, it is not restricted thereto, and various modifications can be made unless deviating from the spirit of the present invention.
The injection-molded product (bumper for an automobile) of the present invention does not have undercut in an as-molded state, because hooks connected to its edge via thin hinges are substantially perpendicular to the parting direction of the die, and thus the nails (and through-holes) of the hooks are substantially in parallel with the parting direction of the die. Accordingly, the injection-molded product can easily be removed from the die. Also, the hooks can be kept substantially parallel with the body, when a separate member (grille) is fixed. Accordingly, only a small number of parts for fixing the separate member are needed, resulting in good efficiency in the fixing operation.
Number | Date | Country | Kind |
---|---|---|---|
2003-391191 | Nov 2003 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/JP2004/017629 | 11/18/2004 | WO | 00 | 1/10/2007 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2005/049300 | 5/19/2005 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
4645250 | Bauer et al. | Feb 1987 | A |
6405819 | Ohkura et al. | Jun 2002 | B1 |
6527317 | Fox et al. | Mar 2003 | B2 |
Number | Date | Country |
---|---|---|
63-41133 | Oct 1988 | JP |
09-089165 | Mar 1997 | JP |
2000-108821 | Apr 2000 | JP |
2000-156921 | Jun 2000 | JP |
2002-059794 | Feb 2002 | JP |
2003-191279 | Jul 2003 | JP |
Number | Date | Country | |
---|---|---|---|
20070222238 A1 | Sep 2007 | US |