US20020121120A1

US20020121120A1 - Method and apparatus for manufacturing extruded parts

Info

Publication number: US20020121120A1
Application number: US10/032,054
Authority: US
Inventors: Frank Kraft; Jerry Ziems; Charles Downing
Original assignee: Brazeway Inc
Current assignee: Brazeway Inc
Priority date: 2001-01-03
Filing date: 2001-12-21
Publication date: 2002-09-05

Abstract

A method of manufacturing micro-multi-port tubing including actuating a hydraulic press to apply a force to a billet to extrude material through a die opening. The die opening defines at least two distinct segments to produce a single, unitary, continuous micro-multi-port extrusion strand having at least two distinct segments being interconnected by a web section. The method further includes separating the single, unitary, continuous micro-multi-port strand to substantially remove and/or reshape the web section to define at least two separate and independent micro-multi-port tubing segments from a single extrusion strand.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/259,474, filed Jan. 3, 2001, the disclosure of which is hereby incorporated herein by reference.[0001]

FIELD OF THE INVENTION

The present invention generally relates to a method of manufacturing heat exchanger tubing and, more particularly, relates to a method of simultaneously extruding multiple integral segments of micro-multi-port, heat exchanger tubing in a single extrusion strand.

BACKGROUND OF THE INVENTION

As is well know to those skilled in the art, automotive climate control systems typically employ parallel flow condensers, additional heat exchangers, and gas coolers. These systems are often made with extruded hollow tubing. However, recently, with the advent of R744 cooling refrigerant, which is a CO ₂refrigerant, new condenser cores and the like have been redesigned, which benefit from a relatively new configuration for such extruded tubing. This new configuration is generally known as micro channel tubing, micro-multi-void tubing, and micro-multi-port tubing (MMP).

Micro-multi-port tubing generally includes a plurality of internal ports or channels that extend through an extruded body. The plurality of internal ports are each capable of carrying a fluid therethrough. Unfortunately, prior art extrusion technology is not capable of economically producing large quantities of this micro-multi-port tubing.

Specifically, prior art extrusion technology typically provides an extrusion die having a single die opening. Material, such as an aluminum alloy in the form of a billet is extruded through the die opening in response to pressure being applied by a hydraulic press or ram. However, the minimum size of the extrusion capable of being formed is dependent upon an extrusion ratio.

Briefly, the extrusion ratio refers to the relationship between the internal cross-sectional area of the billet container and the cross-sectional area of the die opening (i.e., the extrusion profile(s)). For a particular extrusion press, alloy, extrusion die and other process conditions, there exists an upper limit for the extrusion ratio, above which extrusion is overly difficult or cannot take place at all. This upper limit is dependent on a number of factors, including the force capacity of the hydraulic press, the alloy used, the particular extrusion profile, and process conditions such as temperature and speed. In typical extrusion applications, the extrusion ratio is often in the range of about 70:1 or less. However, in modern multi-port tubing applications, the extrusion ratio can be from 500:1 to 2000:1. These ratios are significantly higher than conventional extrusion applications and, thus, require either higher force capacity extrusion presses, which require additional cost investment, or reduced diameter billets, which reduces the production efficiency.

The industry trend to develop ever smaller and more efficient heat exchangers continues to drive the commercial demand for smaller micro-multi-port tubing. However, as can be appreciated from the foregoing, in order to extrude smaller multi-port tubing, it is necessary to either install costly high-capacity extrusion presses or reduce the actual extrusion ratio to be below the upper limit that can be successfully extruded. As described above, with the desire to achieve even smaller micro-multi-port tubes, extrusion ratios in years to come could approach 3400:1 to 7500:1. Thus, existing extrusion presses impose a practical limit on extrusion profile sizes and may not be capable of satisfying the needs of the future.

Existing extrusion systems consist of a single extrusion press having down-line equipment for coating, cooling, inspecting, and winding individual extrusion strands having single segments. To increase production of micro-multi-port channel tubing, additional die openings have been used in a single extrusion press to extrude multiple strands simultaneously, each having a single segment. However, the rate of extrusion of these multiple strands from a single press typically varies relative to each other. Therefore, downstream equipment that is dependent on the rate of extrusion, such as the winding system and inspection system, cannot be used for multiple strands. Consequently, in order to extrude multiple strands from a single extrusion press, it is necessary to purchase and install separate and distinct downstream equipment, such as multiple winding systems and inspection systems. For each additional strand that is extruded from the press, another line of downstream equipment must be purchased at considerable expense and utilization of floor space.

Accordingly, there exists a need in the relevant art to provide a method of manufacturing multiple segments of micro-multi-port tubing without requiring an increase in press capacity nor excessive additional downstream equipment. Furthermore, there exists a need in the relevant art to provide a method of manufacturing micro-multi-port tubing that is capable of simply and conveniently increasing the production of a given existing system. Still further, there exists a need to provide a method of manufacturing micro-multi-port tubing that overcomes the disadvantages of the prior art.

SUMMARY OF THE INVENTION

According to the principles of the present invention, an advantageous method of manufacturing micro-multi-port tubing is provided. The method includes actuating a hydraulic press to apply a force to a billet to extrude material through a die opening. The die opening defines at least two distinct sections to form a single, unitary, continuous micro-multi-port extrusion strand having at least two distinct segments interconnected by a web section. The method further includes separating the single, multi-segmented, unitary, continuous micro-multi-port extrusion strand to substantially remove and/or reshape the web section to define at least two separate and independent micro-multi-port tubing segments. According to the principles of the present invention, multiple extrusion segments are extruded from a single strand through an individual die opening. In addition, this invention also encompasses multi strand extrusion, in which several multi-segmented profiles are extruded from a single extrusion press.

Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: [0012]
FIG. 1 is a perspective view illustrating a micro-multi-port extrusion system according to the principles of the present invention; [0013]
FIG. 2 is a perspective view illustrating a micro-sized, multi-segmented, multi-void tube extruded from the extrusion system of FIG. 1; [0014]
FIG. 3 is a perspective view illustrating separation of the multi-segmented, multi-void tubes into distinct and independent sections; [0015]
FIG. 4 is an end view illustrating the multi-segmented, multi-void tube; [0016]
FIG. 5 is an enlarged end view illustrating the connection between two micro-multi-port tubes; and [0017]
FIG. 6 is an enlarged cross-section view illustrating the connecting web section of the micro-sized, multi-segmented, multi-void tube being cut by a circular cutting blade.[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. For example, the principles of the present invention may find utility in a wide variety of extruding applications. Therefore, the description of the preferred embodiment should not be construed to be limited to micro-multi-port applications. [0019]
The inventive method of and apparatus for simultaneously extruding a continuous micro-multi-port tube strand consisting of at least two coupled extrusion segments, which are later separated, provides a number of distinct advantages over prior art devices. The present invention enables multiple, extremely small, or micro, profiles to be extruded using an existing or small-capacity press that would otherwise be unable to accommodate such high extrusion ratios if the segment was extruded individually. Moreover, the present invention enables the productivity of existing extrusion systems to be increased directly as the number of extrusion segments extruded simultaneously increases. It should be noted that additional die openings may be used to simultaneously extrude multiple, multi-segment strands. [0020]
Referring to the drawings, a micro-multi-port extrusion system, generally indicated at [0021] 10, is provided for extruding a micro-sized, multi-segmented, multi-void strand 12 therefrom. Extrusion system 10 generally includes a press ram 14, a billet 16, and an extrusion die 18. Press ram 14 includes a head portion 20 and a stem portion 22. However, it should be understood that press ram 14 might have any shape suitable for extrusion.
Head portion [0022] 20 of press ram 14 is positioned adjacent a first end 24 of billet 16. Billet 16 is illustrated as being generally cylindrical in shape and having a diameter generally indicated as B. According to the preferred embodiment, billet 16 is disposed within a container having open ends in accordance with a hot extrusion process. That is, billet 16 is heated to reduce the flow stress of the material and increase ductility. Preferably, this material is aluminum and, more preferably, is Aluminum Association 1XXX or 3XXX series alloy. An opposing second end 26 of billet 16 is positioned adjacent extrusion die 18.
As best seen in FIG. 1, extrusion die [0023] 18 includes a die opening 28. Die opening 28 defines an aperture through extrusion die 18 capable of receiving and forming the hot material into multi-segmented strand 12.
Specifically, as seen in FIGS. 2, 4, [0024] 5, and 6, multi-segmented strand 12 includes a plurality of distinct segments 30 each having a plurality of longitudinal voids 31. The plurality of distinct segments 30 are interconnected via a plurality of webs 32 extending therebetween. The plurality of webs 32 serves to couple adjacent pairs of segments 30 to form a unitary multi-segmented strand 12. Moreover, the plurality of webs 32 are each preferably small in both height and width to be easily removed or reshaped following extrusion, as will be described below. On the other hand, it is preferable the plurality of webs 32 are each sufficiently sized to maintain connection of the plurality of distinct segments 30 during post extrusion processes, such as coiling, sizing, lateral cutting, straightening, and the like. Ideally, each of the plurality of webs 32 further are uniform in shape and thickness, however, varying profiles may also be used.
A distinct advantage of the present invention is the ability to extrude micro-multi-port tubing while decreasing the extrusion ratio of [0025] extrusion system 10. Specifically, as described above, the extrusion ratio refers to the relationship between the cross-sectional area of billet 16 (constrained by a container) and the cross-sectional area of die opening 28. This value is related to the amount of work required for extrusion and thereby relates to the force capacity of the extrusion press. In the prior art case, the cross-sectional area of the die opening is equal to the cross-sectional area of the single extruded profile, A_se. For discussion purposes, it will be assumed that this prior art case would produce an extrusion ratio of 4400:1. However, in accordance with the present invention, the cross-sectional area of die opening 28 is equal to the total cross-sectional area of multi-segmented strand 12, which in the case of a dual segment 30 extrusion would equal approximately 2A_se. In practice, the cross-sectional area of die opening 28 would be greater than 2A_se, due to the additional cross-sectional area of the plurality of webs 32. According to the principles of the present invention, the extrusion ratio is thus reduced to approximately 2200:1. Furthermore, additional segments 30 may also be included to further minimize the extrusion ratio. As described above, the reduction of the extrusion ratio enables existing and/or lower cost presses to be used, thereby reducing the cost of manufacture. Additionally, it is possible to extrude smaller segments 30 than could otherwise be extruded, without the purchase of high capacity extruders. Still further, it must be understood that the present invention enables multiple profiles or segments to be extruded simultaneously, thereby increasing the overall productivity of the system.
Referring now to FIGS. [0026] 3-6, once multi-segmented strand 12 is extruded from extrusion system 10, it is necessary to separate multi-segmented strand 12 into its distinct segments 30. Preferably, this may be completed through a number of methods, such as, but not limited to, slitting, shearing, or blanking. However, most preferably, such separation is accomplished by slitting using a circular cutting blade assembly, generally indicated at 34. Circular cutting blade assembly 34 includes a support rod 36 carrying a plurality of circular cutting blades 38. As best seen in FIG. 6, it is preferable that circular cutting blade 38 is slender to enable a cut generally adjacent a main body portion 40 of segment 30. That is, it is preferable that all excess material from web 32 is removed and/or reshaped in this step to eliminate the need for further processing, thereby producing a final preferred shape 42. It should be understood that the narrower circular cutting blade 38 further enables the size of web 32 to be minimized, as seen in FIG. 6. However, it must further be understood that web 32 may simply be reshaped to provide such separation of segments 30. The removal and/or reshaping of web 32 is important to make the now separated segments conform to the final preferred extrusion shape.
In operation, material, such as an aluminum alloy billet [0027] 16, is supported by a container that is open on both ends. Hydraulic press 14 applies a force against billet 16, thereby increasing the stress within billet 16. When the applied stress exceeds the stress at which the material plastically deforms, flow in and through the die commences. Consequently, flowing material is forced out of die opening 28 to form a single, continuous, multi-segmented strand 12 having a plurality of distinct segments 30 interconnected by a plurality of webs 32. At this point, other processing steps may be included, such as coiling of the multi-segmented strand 12, cutting pieces into specific lengths, straightening, and the like. However, according to the present invention, single multi-segmented strand 12 is further separated into its distinct segments 30 using a plurality of circular cutting blades 38. Preferably, the plurality of circular cutting blades 38 serves to reshape and remove any excess material of webs 32, thereby require no additional processing. However, if need be, further processing of each distinct segment 30 may be completed according to the necessary specifications of the application.
According to the principles of the present invention, a method of manufacturing micro-multi-port tubing is provided that is capable of simultaneously extruding multiple sections or segments without requiring an increase in press capacity. Furthermore, the method according to present invention enables multiple segments to be extruded from one extrusion die as a single extrusion strand, such that no speed difference between such multiple segments can exist. This enables the multi-sectioned, single strand to be extruded through a single die opening and processed using a single conventional winder system, cutting system, and other post extruding equipment. Moreover, this multi-segmented, single strand method further enables more convenient and efficient post extrusion processing, because the multi-segments can be processed simultaneously. Therefore, the present invention is capable of increasing the production of a given existing system. [0028]
The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention. [0029]

Claims

What is claimed is:

1. A method of extruding tubing comprising:

providing an extruding system having a billet of material, a pressure ram, and a die member, said die member having a die opening defining at least two distinct segments;

actuating said pressure ram to apply a force to said billet to extrude said material through said die opening of said die member to form a single, unitary strand having at least two distinct segments being interconnect by a longitudinally extending web section; and

separating said single, unitary strand along said longitudinally extending web section to define at least two separate and independent segments.

2. The method according to claim 1 wherein said step of separating said single, unitary strand along said longitudinally extending web section to define said at least two separate and independent segments includes cutting said web section using a circular blade.

3. The method according to claim 1 wherein said step of separating said single, unitary strand along said longitudinally extending web section to define said at least two separate and independent segments includes cutting said web section using a slitting device.

4. The method according to claim 1 wherein said step of separating said single, unitary strand along said longitudinally extending web section to define said at least two separate and independent segments includes shearing said web section.

5. The method according to claim 1 wherein said step of separating said single, unitary strand along said longitudinally extending web section to define said at least two separate and independent segments includes blanking said web section.

6. The method according to claim 1, further comprising:

coiling said single, unitary strand prior to said step of separating said single, unitary strand along said longitudinally extending web section to define said at least two separate and independent segments.

7. A method of manufacturing micro-multi-port tubing, said method comprising:

actuating said pressure ram to apply a force to said billet to extrude said material through said die opening of said die member to form a single, unitary, continuous micro-multi-port strand having at least two distinct segments being interconnect by a web section; and

separating said single, unitary, continuous micro-multi-port strand to substantially modify said web section to define at least two separate and independent micro-multi-port tubing segments.

8. The method according to claim 7 wherein said step of separating said single, unitary, continuous micro-multi-port strand to substantially modify said web section to define at least two separate and independent segments includes cutting said web section using a circular blade.

9. The method according to claim 7 wherein said step of separating said single, unitary, continuous micro-multi-port strand to substantially modify said web section to define at least two separate and independent segments includes cutting said web section using a slitting device.

10. The method according to claim 7 wherein said step of separating said single, unitary, continuous micro-multi-port strand to substantially reshape and modify said web section to define at least two separate and independent segments includes shearing said web section.

11. The method according to claim 7 wherein said step of separating said single, unitary, continuous micro-multi-port strand to substantially modify said web section to define at least two separate and independent segments includes blanking said web section.

12. The method according to claim 7, further comprising:

coiling said single, unitary, continuous micro-multi-port strand prior to said step of separating said single, unitary, continuous micro-multi-port strand to substantially remove said web section to define at least two separate and independent segments.

13. A method of manufacturing micro-multi-port tubing, said method comprising:

providing an extruding system having a container for holding a billet, a pressure ram, and a die member, said die member having a die opening defining at least two distinct sections;

actuating said pressure ram to apply a force to said billet to extrude said material through said die opening of said die member to form a single, unitary, continuous micro-multi-port strand having at least two distinct segments being interconnect by a longitudinally-extending web section; and

cutting said single, unitary, continuous micro-multi-port strand along said longitudinally-extending web section to separate said single, unitary, continuous micro-multi-port strand into at least two separate and independent micro-multi-port tubing segments.