WO2018129604A1

WO2018129604A1 - Process for joining tubes

Info

Publication number: WO2018129604A1
Application number: PCT/BR2018/050005
Authority: WO
Inventors: Gerson DE ARAUJO; Gilian DAL POSSO
Original assignee: Whirlpool S.A.
Priority date: 2017-01-13
Filing date: 2018-01-12
Publication date: 2018-07-19
Also published as: BR102017000818A2

Abstract

The present invention concerns the technological field of tubes, tubes joint or tube accessories, more particularly, processes for joining tubes and channels. Problem to be solved: Among the main methods currently used for joining tubes, especially at a compressor terminal, it is cited brazing, which requires the use of high cost materials, presents high energy costs, in addition to having high rework rates. Problem solving: Herein is disclosed a process for joining tubes, preferably applied in discharge tubes of a compressor terminal, which provides joining of these by means of mechanical crimping and sealing of the joint by means of adhesive, without the need for welding, expensive bonding alloys, yet meeting the requirements of reliability, tightness and safety for joining these tubes.

Description

"PROCESS FOR JOINING TUBES"

Field of the Invention

[001 ] The present invention is related to a process for joining tubes, preferably applied in tubes from the inside part to the outside part of a compressor, said process providing tube joining by means of mechanical crimping as a guarantee element of resistance to mechanical stresses and sealing by means of adhesive to guarantee tightness, without the need for welding and/ or expensive joining alloys, yet meeting the reliability, tightness and safety requirements for joining these tubes.

Fundamentals of the Invention

[002] As is known to those skilled in the art, currently, many means are known to provide tube joining, among which we can mention: welding, gluing, coupling with additional elements, and so on. In this sense, it is worth noting that each design/ equipment in which these joining tubes are made have specific requirements, which must be met by each joining method.

[003] About, specifically, the joining of discharge tubes from a compressor terminal, is mentioned the use of a joining process called brazing. This process is widely used and is basically characterized by a type of welding, where a brazing alloy is applied to the base metal joint (to be joined). This brazing alloy must have a lower melting point than the base metals, so when heating the assembly (with torch, for example), the brazing alloy melts and when it solidifies again, it provides a union of the base metals.

[004] One of the disadvantageous points of the brazing process is the high cost of these "brazing alloys" which are usually made up of elements such as: zinc, copper or silver; elements of high value. There is also the high energy cost of this process, mainly to melt the brazing alloy.

[005] Another disadvantageous point in the brazing process is found in the high rework rate, given the fact that this process is very sensitive, especially regarding installation of the assembly and, once the brazing alloy is solidified, it is virtually impossible to reverse the flawed process, losing all the set that would be joined.

[006] In continuity with the foregoing, it will be appreciated that the prior art already provides for other methods of tube joining, as shown in document US 201 1 /094656 which describes a method in which tubes are joined by the application of a thermally curable adhesive. This method, although providing joint and sealing, does not guarantee any safety, since mechanical stresses suffered by the tubes can easily break the adhesive, since the adhesive in this case has a structural and sealing function.

[007] Still in relation to the state of the art, document US 2009/188269 describes a joint method which also makes use of an adhesive substance in the junction region of the tubes, which are applied in refrigeration systems. Similar to the previously discussed, these adhesive substances (without the use of a structural element) are not able to withstand stronger mechanical stresses, which would lead to failure of the joint.

[008] Finally, the prior art document US 2003/146624 provides a method of joining tubes which makes use, in addition to an adhesive compound, of an additional threadable element disposed over the junction region. Although this additional element is supposed to guarantee mechanical safety at the junction, it should be noted the cost involved in the acquisition of a supplementary piece, as well as the complexity in installing the assembly. In addition, in equipment of reduced dimensions (such as in compressors) this solution would not be applicable, given the space required for mounting and fitting of this additional element.

[009] Thus, and in accordance with what has been observed above, the prior art fails to provide a method for joining tubes capable of providing reliability, tightness, safety and low cost in the joining of tubes, especially, applied in a compressor terminal. [010] It is based on this premise that the invention in question arises.

Objectives of the Invention

[01 1 ] Thus, it is a goal of the present invention to disclose a process for joining tubes that adequately meets the requirements of reliability, structural, tightness and safety for joining these types of tubes.

[012] It is further a goal of the present invention to disclose a process for joining tubes which withstands high mechanical stresses applied to the joint, without the need for addition of other structural elements to the joining process.

[013] In addition, it is another goal of the patent of invention in question to disclose a process for joining tubes with low energy cost and low material costs.

[014] Finally, it is a goal of the present invention to disclose a process for joining tubes which can be applied in environments with reduced dimensions and in ducts of reduced dimensions.

Brief Description of the invention

[015] All the goals of the patent of invention are achieved by means of a process for joining tubes comprising the following steps of: inserting a first tube, at least partially, inside a second tube, so as to define a intersection region; applying compression force on at least part of the perimeter of the intersection region of the first tube with the second tube, so as to define a junction region; applying an adhesive on at least part of the perimeter of the intersection region of the first tube with the second tube.

[016] Further, the goals are achieved by means of a process wherein the compression force applied at one or more points of the perimeter of at least one intersection region reduces the diameter of the first and second tubes to provide mechanical crimping. [017] Finally, the goals of the present invention are also achieved by means of a process wherein the adhesive applied to at least part of the perimeter of the intersection region seals said intersection region.

Brief Description of Drawings

[018] The present invention will be more fully understood based on the accompanying drawings, in which:

[019] Figure 1 shows a perspective view of the tubes junction, according to the process of the present invention.

[020] Figure 2 shows a cross-sectional view of the tubes junction, according to the process of the present invention.

[021 ] Figure 3 shows view of variant embodiments of the tubes junction, according to the process of the present invention.

Detailed Description of the Invention

[022] The present invention will be more fully described and explained based on the accompanying drawings, which are of a merely exemplifying and not limiting character, since adaptations and modifications may be made without thereby departing from the scope of the claimed protection.

[023] The present invention is related to a process for joining tubes, especially applied at a compressor discharge terminal, the method comprising the steps of: inserting a first tube 1 , at least partially, inside a second tube 2, so as to define an intersection region 5 between said tubes; applying compression force on at least part of the perimeter (on at least one point) of the intersection region 5 of the first tube 1 with the second tube 2, in order to define at least one junction region 3; applying an adhesive 4 on at least part of the perimeter of the intersection region 5, so as to seal said intersection region.

[024] Initially, it is important to note that in the intersection region 5, the first tube 1 should have a smaller diameter than the second tube 2, this because, this first tube 1 should be inserted inside the second tube 2. Exception is made in the case in that at least one of the tubes is made of flexible material; being that, for this example, the diameter of the tubes becomes variable.

[025] It is to be understood that the first tube 1 and the second tube 2 are preferably made of metal. However, tubes of miscellaneous materials may be used in the process described herein.

[026] As can be seen in figure 1 , the insertion of the first tube 1 inside the second tube 2 creates an intersection region 5 (detached in dotted lines) between these tubes. The extent of this intersection region 5 may vary according to the application given to the tubes.

[027] Further, as can be seen in figure 1 , since the intersection region 5 between the first tube 1 and the second tube 2 is defined; a compression force is applied to at least part of the perimeter defined by the intersection region 5. This compression force then defines a junction region 3. The compression force applied on the first tube and the second tube 2 must be capable of reducing the diameter at one or more points of the first tube 1 and of the second tube 2. In other words, the junction region 3 defines a squeeze area (reduction of the diameter) of the tubes.

[028] Herein, an intrinsic advantage of the joining process of the present invention is emphasized, since the compression force applied on the first tube 1 and the second tube 2 defines at least one junction region 3 which, in turn, features a mechanical crimp (coupling) between said tubes. This is because, since the first tube 1 and the second 2 are compressed together, both are crimped (coupled), so that it becomes very difficult to separate them, even with the application of a stress in the longitudinal axis of these tubes. [029] It is essential to report that the clearance in the first tube 1 and in the second tube 2 is greatly reduced, in this way, an optimum mechanical crimping is achieved.

[030] Preferably, the compression force applied on the first tube 1 and the second tube 2 plastically deforms these tubes.

[031 ] Referring in particular to the junction region 3, it is noted that it is preferably disposed throughout the vicinity of the first tube 1 of the second tube 2. However, it is noted that said junction region 3 may be applied in only part of the perimeter of the tubes, depending on the application which will be given to these.

[032] In addition, it is important to note that many junction regions 3 may be provided in the intersection region 5 of the first tube 1 with the second tube 2, each junction region 3 defining an additional area of crimping between the tubes.

[033] Regarding the compression force, it can be applied with the aid of pressing tool, squeezing machine, crimping pliers or any other suitable tool or equipment for this purpose.

[034] In a preferred embodiment, the compression force is applied by a method called diameter reduction, which may be by means of routing, crimping, in which a mechanical element is used to exert the compression force on the tubes which are then rotated so that the junction region 3 is provided throughout the vicinity of the tubes.

[035] Still referring to figure 1 , it is noted that, in addition to the crimping of the first tube 1 with the second tube 2, an adhesive 4 is applied in the intersection region 5. Especially, the adhesive 4 is applied between the junction region 3 and the limit of the intersection region 5.

[036] The main function of this adhesive 4 is to seal the intersection region 5, so that the joining of the tubes is tight, that is, there should be no leakage of any fluids that run through the first tube 1 and the second tube 2.

[037] In a preferred embodiment, the adhesive 4 is of the anaerobic type, however, various types of adhesive elements or adhesive substances may be used, depending on the application that will be given to the tubes. The curing time can be accelerated by ultraviolet process or the like.

[038] Further, it is essential to report that the jointing process, as described in the present invention, may be applied in a plurality of serial joining tubes, not being restricted to the joining of only two tubes.

[039] Finally, it is important to note that the process for joining tubes of the present invention is especially applied to discharge tubes of a compressor terminal.

[040] Based on all the foregoing, and bearing in mind the various plausible embodiments for the present invention, it is seen that the present invention provides a process for joining tubes which overcomes the problems reported in the prior art and has intrinsic advantages for the application which it is intended.

Claims

1 . Process for joining tubes, characterized by the fact that it comprises the steps of:

- inserting a first tube (1 ), at least partially, inside a second tube (2), so as to define an intersection region (5);

- applying compression force to at least part of the perimeter of the intersection region (5) of the first tube (1 ) with the second tube (2), so as to define a junction region (3);

- applying an adhesive (4) on at least part of the perimeter of the intersection region (5) of the first tube (1 ) with the second tube (2).

2. Process, according to claim 1 , characterized by the fact that the first tube (1 ) has, in the intersection region (5), a smaller diameter than the second tube (2).

3. Process, according to claim 1 , characterized by the fact that the compression force applied on at least part of the perimeter of the intersection region (5) reduces the diameter of the first tube (1 ) and of the second tube (2).

4. Process, according to claim 1 , characterized by the fact that the compression force applied on at least part of the perimeter of the intersection region (5) provides mechanical crimping between the first tube (1 ) and the second tube (2).

5. Process, according to claim 1 , characterized by the fact that the adhesive (4) is anaerobic with the curing time accelerated by ultraviolet process or the like.

6. Process, according to claim 1 , characterized by the fact that the adhesive (4) seals the intersection region (5) of the first tube (1 ) with the second tube (2).

7. Process, according to claim 1 , characterized by the fact that the compression force is applied by pressing tool, squeezing machine, crimping pliers, or the like.

8. Process, according to claim 1 , characterized by the fact that it is applied a plurality of serial joining tubes.

9. Process, according to claim 1 , characterized by the fact that it is applied for the joining discharge tubes of a compressor terminal.