Metal deforming – By extruding through orifice – With metal-deforming other than by extrusion
Reexamination Certificate
2000-06-22
2001-12-11
Tolan, Ed (Department: 3725)
Metal deforming
By extruding through orifice
With metal-deforming other than by extrusion
C072S253100, C165S080300
Reexamination Certificate
active
06327886
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to a method of producing a heat transfer member, wherein at a first step a work piece is produced comprising a curved base portion with an outer surface and an inner surface, and a number of flanges projecting from the outer surface of the base portion, and in a second step the heat transfer member is formed by straightening the base portion so that it becomes essentially plane.
The invention is also related to a device for producing a work piece for a heat transfer member, whereby the device is adapted to be supplied with a congealable material to an opening comprised in the device, the design of which opening defines the cross-section of the work piece, whereby the opening comprises a curved opening portion with an outer surface and an inner surface, and a number of notches projecting outwardly from the outer surface.
Further, the invention relates to a work piece intended to be formed into a heat transfer member, the work piece comprising a curved base portion with an outer surface and an inner surface, and a number of flanges projecting from the outer surface of the base portion.
Heat transfer devices are used for cooling or heating an object. The field of the invention comprises heat transfer devices within a plurality of application fields, as for example cooling of semi-conductors.
PRIOR ART
The heat transfer member is formed with a base and a number of flanges projecting from the same according to prior art. The base and the flanges may be formed in a plurality of different ways depending on the desired magnitude of the heat transfer, the design of the object intended to be heat transferred, the available space, and so on.
The heat transfer member is arranged with the side of the base opposite the flanges directed towards the object to be cooled.
The heat transfer takes place when the flanges are subjected to a cooling medium in the form of, for example, air or water in that heat is conducted from the object through the device and to the cooling medium.
Heat transfer members are preferably made of a material with a high heat conductivity. Such materials are, for example, gold, copper, and aluminum, as well as different alloys of the same, Aluminum and aluminum alloys are materials well suited for being used for heat transfer devices due to their high conductivity, good deformability, and the fact that they are relatively inexpensive. According to prior manufacturing techniques aluminum is injection-molded or extruded through a tool at an increased temperature and solidified to an intended design. The so-called aluminum profile is formed by the injection-molding or extrusion. The aluminum profile may thereafter be cut into lengths decided for the use in question.
To achieve a good cooling capacity of the device, it is desirable to arrange the device with an area as wide as possible for emitting heat as well as for absorbing cold. Thus, it is desirable to form the flanges with a large height and with small distances adjacent flanges. The height of the flanges and the distance between adjacent flanges are according to previous, known manufacturing methods limited by the tools used for the manufacturing. The tool, through which the material is injection-molded or extruded, is formed with elongated elements corresponding to the gaps between the flanges in the manufactured profile. Said tool is subjected to high loads during manufacturing due to the fact that material of a relatively high temperature is pressed through the same. The elongated elements may be deformed or broken if they have too large a height in relation to the width thereof.
A solution to this problem is known through U.S. Pat. No. 4,187,711. The heat transfer member is produced in two steps. In a first step, a work piece is produced comprising a curved base portion with an outer surface and an inner surface, and a number of flanges projecting from the outer surface, and in a second step the heat transfer member is formed by straightening out the base portion so that it becomes essentially plane. The ends of the base portion is provided with gripping means which fit together with a couple of pulling tools for straightening out the base portion. The gripping means are arranged along the prolongation of the base portion and perpendicularly to the flanges. During the straightening out of the curved base portion, the work piece is placed around an axis, whereby one of the gripping means is attached to the axis and the other gripping means is attached to the pulling tool. The base portion is straightened by a pulling force applied to one end of the base portion through the pulling tools, whereby the axis exerts a counter force on the other end of the base portion.
To achieve the heat transfer, the heat transfer member is arranged with the side of the base opposite the flanges directed towards the object to be cooled or heated. Usually, the surface to be applied against the heat transfer member is plane. For the heat transfer to be as good as possible in such an application, it is important that the base portion is completely plane. A problem with this method of manufacturing is that the base portion cannot be straightened out completely After the straightening, the base portion is still slightly curved, which has to be treated afterwards to make it plane. This treatment could, for example, be the application of a bumping force against the base portion with any kind of striking apparatuses. This method is time consuming and is not suitable for manufacturing large series.
One way of at least partially solve this problem is shown in PCT/SE98/00671. By arranging effect members inside the base portion, a distance of momentum between the base portion and the pulling point is achieved. Thanks to this distance of momentum, it is possible to straighten the base portion completely when applying a pulling force to the effect members in a direction substantially parallel with the longitudinal axis of the base portion. A problem with this manufacturing method is that the base portion after the straightening still is not completely plane. During the straightening, there is a deformation of the material in the base portion which means that the material in the inner part of the curved base portion is straightened out and the material in the outer part is pulled together. During the pulling, the material in the inner part is more straightened out than the material in the outer part is pulled together, and as a consequence of that, there is an over-bending of the base portion so that the center of the base portion becomes slightly depressed. To obtain a completely plane heat transfer member, a subsequent treatment is necessary, for example by applying a bumping force against the base.
SUMMARY OF THE INVENTION
The object of the present invention is to obtain a method of producing a heat transfer member which method will not require any subsequent treatment since the heat transfer member will be sufficiently plane for use directly after the straightening of it.
Another object of the present invention is to obtain a device for producing a work piece for a heat transfer member and a work piece intended to be formed into a heat transfer member, which both makes it possible to use said method which does not require any subsequent treatment,
What characterizes a method, a device and a work piece according to the invention will become clear from the appended claims.
The object of the inventive method is achieved by producing the work piece in a first step so that the distance between the outer and the inner surface of the base portion is increasing from its ends towards its central part. During the straightening, the deformation begins in the center of the curved base portion, where the distance of momentum is the largest. As soon as the deformation begins in the material, an axis of momentum is formed on each side of the center of the base portion. The bending moment is the largest at the axis of momentum. The over-bending resulting from said known method depends on the fact that t
AB Webra Industrl
Tolan Ed
Vigil Thomas R.
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