Plastic article or earthenware shaping or treating: apparatus – Shaping surface including means to release or remove product... – By means releasing article from interiorly placed shaping...
Reexamination Certificate
2001-03-12
2003-09-23
Mackey, James P. (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Shaping surface including means to release or remove product...
By means releasing article from interiorly placed shaping...
C425S443000, C425SDIG005, C249S059000
Reexamination Certificate
active
06623265
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a mould which allows ready manufacture of a fan which has a hub and a plurality of helical blades extending from the hub. The mould can be a two-part mould and is able to form a fan which can have multiple overlapping blades. In this manner, fans can be moulded readily from any suitable mould material, e.g. plastics or metal.
BACKGROUND ART
Conventional axial flow fans are relatively easy to mould. A two-part mould may be employed and each part of the mould moves directly away from its counterpart to eject the newly formed fan. These fans can range in diameter from between 20 mm to up 500 mm. For instance, small cooling fans to cool computer chips can be formed in this manner as can larger diameter fans.
Fans which have blades which overlap each other when viewed in plan cannot easily be moulded using a two-part mould as described above. That is, it is not possible to simply rotate the two mould parts to free the mould parts from the fan blades. It is also found that fans having helical blades are not able to be moulded in a manner which is used for conventional axial flow fans.
It is known to mould fans having a more complex blade shape and profile. These moulds cannot be opened simply by drawing the two parts away from each other. Instead, the moulds need to be mechanically rotated which forces the parts to come away from each other in the axial direction. This type of mould arrangement does allow fans to be made having a slight degree of blade overlap, but the process is unsuitable for fans having quite significant blade overlap. Fans having overlapping blades have advantages in supplying a higher volume and/or pressure of air and these fans find particular suitability in cooling of computer chips and also other uses where a high volume air flow is required.
It is well-known to manufacture a variety of plastic objects using a two-part mould where the moulds have to be separated with rotation. For instance, when moulding plastic caps or plastic bottles, the mould halves cannot disengage by simply pulling them apart and instead additional mechanical means is required to rotate the mould while it is being pulled apart. This requires additional fairly complex powered components, and it would be an advantage to have a mould system where the mould components can be separated with rotation but where there is no additional external mechanical means required to rotate the article out of the mould.
OBJECT OF THE INVENTION
It is an object of the invention to provide a mould which allows manufacture of fans having a hub and a plurality of helical blades extending from the hub and which may overcome the abovementioned disadvantages or provide the public with a useful or commercial choice.
In one form, the invention resides in a mould for the manufacture of a fan having a hub and a plurality of helical blades extending from the hub, the mould having blade moulding cavities which are formed such that
(a) any imaginary line extending from the rotational axis of the fan to be formed in the mould and through the blade cavity from the blade root to the blade tip intersects the rotation axis at the same angle as any other imaginary line extending in a similar manner,
(b) all the imaginary lines are identical in curvature, or are all linear, and,
(c) any said imaginary line can exactly replace any other said imaginary line.
In one form, the imaginary lines are all identical and linear to allow a fan to be moulded having blades which extend in a helical manner about the hub but where the blades themselves are linear between the blade root and the blade tip.
In another form, the imaginary lines are all identical and are curved. In this form, the mould can manufacture a fan having blades which extend in a helical manner about the hub but where the blades are curved either in a simple curve or in a complex curve between the blade root and the blade tip.
In another form, the blade cavities overlap each other such that the formed fan has overlapping blades. By having the cavities formed in the manner described above, a fan having overlapping blades can be mass produced from settable mouldable material (e.g. plastic) using a two-part mould.
Preferably, the mould has a hub cavity a part of which is spherical or conical. For instance, the hub cavity can have a first part which is generally cylindrical, and a second part which is spherical or conical or otherwise tapering, with the blade cavities being such that a single formed blade can extend over a cylindrical part and a spherical or conical part while still allowing the fan to be injection moulded or otherwise moulded using a simple two-part mould. Previously, fans having blades which overlapped and which extended over a spherical or conical hub portion were extremely difficult if not impossible to readily mass produce using a two-part mould.
The blade cavities in the mould can be formed such that any point on the formed blade tip edge is the same distance from the rotation axis of the fan as any other point.
The mould can be a two-part mould where the two parts come together to define at least part of the above mould cavities. With the mould cavities being as described above, it is now possible to have the two mould parts merely pulled away from each other without requiring any external separate mechanical rotation means. The newly formed fan in the mould can provide surfaces that pressure can be applied to, to cause auto rotation of one of the mould parts (and possibly both of the mould parts) as the parts are pulled away from each other. This can be made possible due to the particular configuration of the mould cavities as described above. One or both of the mould parts can rotate freely which allows the mould parts to auto rotate as the parts are pulled away from each other.
REFERENCES:
patent: 4043385 (1977-08-01), Petrenchik
patent: 4871505 (1989-10-01), Lapeyre
patent: 5409656 (1995-04-01), Naruse et al.
patent: 5547365 (1996-08-01), Chuang
patent: 4428161 (1995-07-01), None
patent: 62117717 (1987-05-01), None
patent: 63005916 (1988-01-01), None
patent: 8066745 (1996-03-01), None
patent: PCT/EP97/01764 (1997-04-01), None
Heckenberg Donald
Hoffman Wasson & Gitler PC
Jetfan Technology Limited
Mackey James P.
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