Pipes and tubular conduits – Structure
Reexamination Certificate
1999-10-12
2001-02-06
Brinson, Patrick (Department: 3752)
Pipes and tubular conduits
Structure
C138S109000, C264S239000, C264S259000, C425S542000
Reexamination Certificate
active
06182707
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a hollow tubular body for an air intake duct, and a mold and a molding method for the hollow tubular body, and more particularly to a hollow tubular body for an air intake duct which is suitable for a mechanical supercharger (hereinafter referred to as an “MSC” in this specification) that has been widely used for increasing the volumetric efficiency of internal and external combustion engines of an automobile or the like.
BACKGROUND ART
As resinous intake parts for internal and external combustion engines of an automobile or the like, various ducts have been manufactured by blow molding and an intake manifold has been manufactured by a fusibility core method or welding of a plurality of parts. However, they have not been resinified as an air intake duct for the MSC but have been manufactured by aluminum die casting using a sandmold.
If the sandmold is used, however, a product becomes very rough with a maximum surface roughness of Rz≧50&mgr;m and a mean surface roughness of Ra≈8 &mgr;m. For this reason, it is necessary to perform a grinding work in order to keep a profile irregularity of a supercharger junction. Furthermore, a difference in level is easily caused by mismatch. Therefore, it is also necessary to perform a finishing work for a hose junction.
The reasons why a resin has not been used for the air intake duct for the MSC are as follows.
(1) It is hard to integrally mold a flange portion by the blow molding.
(2) Few resin materials for the blow molding have performance, for example, strength, heat resistance and the like necessary for the air intake duct for the MSC. The resin materials having the performance such as strength, heat resistance and the like are expensive. Moreover, the surface roughness of an internal wall is deteriorated more than in existing items (manufactured by the aluminum die casting).
(3) In the fusibility core method or the welding method of a plurality of parts, the investment for a mold and initial plant should be made greatly. In consideration of plant repayment, a cost is increased more than in the existing items.
An injection molding method using a fused resin and a fluid such as an inert gas or the like together (a gas assist injection method which will be hereinafter referred to as “GAI”) has recently been applied variously as a method for molding a hollow bent tube at a low cost.
The merits of the GAI are as follows: “(1) A mold can be manufactured by simply adding comparatively inexpensive equipment to an ordinary mold for injection molding; (2) Since a flange portion can be molded integrally and a mean surface roughness is small, a grinding work is not necessary; (3) It is possible to select inexpensive resin materials suitable for the present product from a great variety of injection molding resins; (4) It is possible to obtain appearance and dimensional precision equivalent to or more than those of an ordinary injection molded product; (5) A low pressure molding method is used so that the life of the mold can be prolonged; and the like.”
However, the mere GAI has disadvantages, for example, “(1) If a reinforcement (glass fiber or the like) is blended to such an extent that necessary performance is revealed, an internal wall becomes rough in the same manner as in the blow molding; (2) It is hard to obtain the same hollow rate as in existing items (manufactured by the aluminum die casting); and the like.”
In consideration of these problems of the prior art, it is an object of the present invention to provide a hollow tubular body for an air intake duct which can be manufactured at a low cost and has an excellent internal smoothness. It is another object of the present invention to provide a mold capable of stably molding a hollow tubular body for an air intake duct having various sizes and shapes, and a method for molding the hollow tubular body.
DISCLOSURE OF THE INVENTION
In order to attain the above-mentioned object of the present invention, a polyamide resin is selected as a thermoplastic resin. A polyamide resin blended with a proper quantity of reinforcing fiber and a polyamide resin blended with less or no reinforcing fiber are employed as a material. Furthermore, a mold for molding the resin material includes a cavity mold and a core mold. A moving type core having a two-stage structure including a large diameter moving core and a small diameter moving core is provided in the core mold. Thus, the above-mentioned object can be achieved.
The present invention provides a resinous hollow tubular body for an air intake duct which is molded by gas assist injection and integrally communicates from a flange to be coupled to a supercharger to a hose junction by means of a bent tube portion and a straight tube portion, wherein a resin material is a polyamide resin containing 15 to 50 % by weight of reinforcing fiber.
It is preferable that a polyamide resin reinforced with fiber or the like should be used because a balance of heat resistance, impact resistance and strength (tension, bending and compression) and a cost is kept. There are various kinds of polyamide resins in which 46 nylon, 11 nylon and 12 nylon are expensive. Since the 46 nylon has a small temperature range for fusing and a time for obtaining a specific volume suitable for GAI is short, it is hard to perform molding. Since the 11 nylon and the 12 nylon have high fusing viscosities, a poor fluidity is obtained when suitable specific volumes are reached. Similarly, it is hard to perform molding. In this respect, polymetaxyleneadipamide, 66 nylon and 6 nylon do not have such drawbacks. In particular, the polymetaxyleneadipamide is an excellent resin material for the GAI.
Examples of the reinforcing fiber include glass fiber, carbon fiber, aramid fiber, a whisker-shaped reinforcement and the like. It is preferable that the glass fiber should be used because a low cost is required and great reinforcing effects are obtained.
If the quantity of the reinforcing fiber to be added is less than 15% by weight, reinforcing effects cannot be obtained. If the quantity of the reinforcing fiber to be added is more than 50% by weight, a cost is increased and moldability is deteriorated. The resin material is obtained by dry blending (A) a polyamide resin containing reinforcing fiber and (B) a polyamide resin containing no reinforcing fiber or containing less reinforcing fiber than in (A). If the resin material is used for fusing and mixing by the GAI, an island of the resin containing no (or less) reinforcing fiber is ununiformly floated in a sea of the resin containing the reinforcing fiber. If a pressurized fluid is injected, the resin is expanded to envelop the reinforcing fiber. Consequently, the internal smoothness of a molded hollow tubular body is enhanced.
A bellows-shaped concavo-convex portion is provided on an outside of the bent tube portion that a pressurized fluid sent from the supercharger directly strikes, thereby partially changing a thickness. Consequently, it is possible to reduce resonance sounds made by causing the fluid sent from the supercharger to strike an internal wall of the hollow tubular body.
Furthermore, if the hose junction is formed of a straight tube having a length of 30 mm or more, joining with a hose can conveniently be performed.
The present invention provides a mold for molding a resinous hollow tubular body for an air intake duct which is molded by gas assist injection and integrally communicates from a flange to be coupled to a supercharger to a hose junction by means of a bent tube portion and a straight tube portion, wherein a bent tubular cavity and a straight tubular cavity are formed in a cavity mold, a large diameter moving core which has the same shape and dimension as an opening of the flange to be formed by the bent tubular cavity and serves to move in a direction orthogonal to a flange face is provided in a core mold directly connected with the cavity mold, and a small diameter moving core to move in the same direction as the large diameter moving core is provided in the large diamete
Matsumoto Noriaki
Sasatani Yoshiaki
Shiraki Hayato
Bando Chemical Industries Ltd.
Brinson Patrick
Marshall O'Toole Gerstein Murray & Borun
LandOfFree
Hollow tubular body for air intake duct, mold therefor, and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hollow tubular body for air intake duct, mold therefor, and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hollow tubular body for air intake duct, mold therefor, and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2584273