WO2019116399A1

WO2019116399A1 - Friction welding of tube to tube using a guide tool

Info

Publication number: WO2019116399A1
Application number: PCT/IN2018/050846
Authority: WO
Inventors: Muthukumaran SHANMUGAM
Original assignee: National Institute of Technology Tiruchirappalli
Priority date: 2017-12-16
Filing date: 2018-12-17
Publication date: 2019-06-20

Abstract

The present invention relates to a method for welding tube to tube of different metals/materials. More particularly, the present invention relates to a system and method for friction welding of dissimilar tubes. The system for friction welding of dissimilar tubes comprises of a guide tool [4] with a pin [1], a shoulder [2] and a tube to tube welding machine with a spindle [3], a tube to tube welding machine with table [3a], with a tube plate [5] and a tube [6] and a spacer [8]. Advantageously the present invention relates to a guide tool with transition joint designed to weld tube to tube of different metals/materials for different applications.

Description

FRICTION WELDING OF TUBE TO TUBE USING A GUIDE TOOL

FIELD OF THE INVENTION

The present invention relates to a method for welding tube to tube of different metals/materials. More particularly, the present invention relates to a system and method for friction welding of dissimilar tubes. Advantageously the present invention relates to a guide tool with transition joint designed to weld tube to tube of different metals/materials for different applications.

BACKGROUND OF THE INVENTION

Common industrial heat exchangers include multiple tubes placed between two tube sheets and encapsulated in a pressure vessel shell. The friction welding of tube to tube plate process using an external tool (FWTPET) is solid state welding process and successful joints have been achieved in the base materials including dissimilar alloys of aluminum, copper, stainless steel, boiler grade steel, titanium and polymers. The advantages of FWTPET process include capability of dissimilar metal welding, energy efficient, green manufacturing, fast, better mechanical properties, less metallurgical issues, high quality, easy to automate and economical.

In general the material used to construct vehicle chassis and frames is carbon steel or aluminum alloys to achieve a more light-weight construction. Welding of similar and dissimilar metals is a great challenge in replacing steel with aluminum and using of different materials. FWTPET is having good potential applications in automobile fabrication including vehicle chassis and frames. However FWTPET cannot be used to weld tube to tube and plate to plate.

At present Small diameter tubing, defined as round tubing with an outside diameter of 50mm or less, is used in a variety of industrial applications. Tubes are extensively used in almost all engineering industries and the demand for joining of tubes of dissimilar metals are more in industries including aerospace, nuclear, chemical, petroleum, automobile and power.

For joining of small diameter tubing, orbital welding has become the preferred joining method. Orbital tube welding is generally a fusion process in which the edges of the joint are melted and fused together without the addition of filler material. However, this method is generally not suitable for dissimilar metals due to the formation of brittle intermetallic compound at the joint interface. Friction Stir Welding is one of the welding processes used in pipe fabrication industry. In this process, two work pieces are joined together by coalescence created by friction of mechanically driven tool. The tool orbits the pipe and welding is completed by completing one complete rotation of the tool around the pipe. Due to heat generation as the result of applied friction, work piece becomes softer and transforms to plastic state. However, this process are not suitable for small diameter tubes and further the equipments are expensive and the precise control of process parameters are essential to get better joint.

EP3296055A1 discloses a device and method for through friction stir welding of a circular seam on rotation- symmetrical hollow bodies. The invention relates to an apparatus for perfect welding through a round seam at rotationally symmetrical hollow bodies. The object of the invention is to achieve full penetration friction stir welded circumferential welds on pressurized hollow bodies, without determining the penetration depth of RuhrreibschweiBstiftes in shock while simplifying the system technology while ensuring economic benefits. For the primary and secondary shoes are (32, 33) providing the centering and clamping disc with a transversely aligned with one another peripheral to the hollow body axis of the hollow body recess (38), wherein the RuhrreibschweiBstift with its tip has by the impact through an immersion depth which is greater than and the actual wall thickness of the hollow body, that the circular weld seam has a to the recess (38) adapted to weld root. However the above invention only deals with an apparatus for the perfect by welding a circumferential weld on rotationally symmetrical hollow bodies by friction stir welding process.

US5248077A discloses a friction welding and welds made by friction. Friction welding is preformed by linear or non-rotating orbital motion in which both parts to be joined by friction welding are moved in identical paths, out of phase to produce friction until welding temperature is attained, and then in phase, with the parts registered in alignment, during the bonding phase. Because the registered, in phase control of the mechanism is attainable with great certainty and rapidity, friction welding with a far higher precision and accuracy of alignment is attained. The high precision and accuracy of the technique permits application of friction welding to fabrication of parts, such as turbine engines, not usually made by such techniques. A preferred apparatus for practice of the invention involves an opposed pair of orbital tables (110 and 120), on which parts to be joined are mounted and fixed in place by mounts 113 and 123). The parts are aligned and registered and drives (111 and 121) then cause the parts to orbit while they are pressed together by pressure means (14), until friction heats the joint surfaces to welding temperatures. However in this invention friction welding is performed by linear or non-rotating orbital motion in which both parts to be joined by friction welding are moved in identical paths.

US3973715A discloses a friction welding. Butt welding of workpieces of similar or dissimilar materials, such as aluminum to aluminum and/or aluminum to steel, having similar or dissimilar cross sections is accomplished by a frictional welding process wherein the average relative speed of the faying surfaces is between about 4 and about 25 feet per second, the pressure urging the faying surfaces into mutual engagement is between about 7500 and about 15,000 pounds per square inch while energy is supplied to the weld area in the range between about 4000 and about 17,000 foot pounds per square inch of weld area, and the formation of the weld is achieved within about 650 milliseconds. However this invention is about Butt welding of workpieces of similar or dissimilar materials.

US6908690B2 discloses a method and apparatus for friction stir welding. The present invention provides a tool for forming a friction stir weld joint in a workpiece. According to one embodiment, the tool includes a rotatable pin having first and second ends and defining a stirring portion therebetween structured to frictionally engage the workpiece so as to at least partially form the friction stir weld joint. The tool includes a rotatable first shoulder defining an aperture therethrough structured to slidably receive the first end of the pin. The tool also includes a second shoulder defining an aperture structured to receive the second end of the pin such that the pin extends between the first and second shoulders and such that the second shoulder is in rotatable communication with the pin. The first shoulder is structured to rotate independently of the pin and the second shoulder. However the purpose of pin used is to stir.

US9658002B2 discloses a process of friction stir welding on tube end joints and a product produced thereby. A process of producing shell and tube heat exchangers where the ends of the tubes are secured to a tube sheet while reacting applied FSW forces without introducing a crevice or local deformation near the ends of the tubes. In particular, an interference fit is used to lock the ends of the tubes into the tube sheet without flaring or expanding the tube ends. A FSW process is then used to weld the ends of the tubes to the tube sheet. However the interference fit is used to lock the ends of the tubes into the tube sheet without flaring or expanding the tube ends. US4442586A discloses a tube-to-tube joint method. A joint is provided between one tube and another tube without the necessity of a heavy thick-walled metal coupling. The joint includes first and an optional second enlarged portions on a first tube with the second enlarged portion near an end of the second tube. A first shoulder is provided between the first enlarged portion and the main body of the first tube. A second annular shoulder is provided at the junction between the first and second enlarged portions. The end of the second tube slips into the first enlarged portion of the second tube and the second tube is then axially compressed so as to form an annular bead which acts against and is contained by the second enlarged portion of the first tube. This axial compression provides both a mechanical interconnection so that the tubes will not axially separate despite fluid pressure or mechanical force, and also provides a fluid tight seal at the annular bead and the second shoulder or second enlarged portion. The foregoing abstract is merely a resume of one general application, is not a complete discussion of all principles of operation or applications, and is not to be construed as a limitation on the scope of the claimed subject matter. The above invention is deals with interference fit but not welding processes.

Background art has a disadvantage that they are not designed for the welding of different metals/materials and are not designed for the welding of the tube to tube using a guide tool of the same machine. It is a purpose of the present invention to design the machine to weld tube to tube.

Accordingly, there exists a need for a method for welding tube to tube of different materials. Further, there exists a need for a machine for welding tube to tube with transition joint designed to weld tube to tube of different metals/materials for different applications. Further there exists a system for friction welding of dissimilar tubes.

SUMMARY OF THE INVENTION

One or more of the problems of the conventional prior art may be overcome by various embodiments of the present invention.

It is the primary aspect of the present invention to provide a system for friction welding of dissimilar tubes, comprising:

a guide tool [4] with a pin [1], a shoulder [2] and a tube to tube welding machine with a spindle [3], a tube to tube welding machine with table [3a], with a tube plate [5] and a tube [6]; and

a spacer [8], wherein the guide tool [4] is assembled in a machine comprising of the spindle [3], the machine table [3 a] and a tool holder,

wherein the guide tool [4] is fixed to the spindle [3] of the machine, wherein the workpiece consisting of the tube plate [5] and the tube [6] is assembled in the machine table [3a] using a backing block [7] and the spacer [8], wherein the tube [6] and tube plate [5] of the workpiece is assembled on the machine table [3a] with the backing block [7] and the spacer [8], and characterized in that the tube plate [5] and the tube [6] are of different materials/metals, and

wherein the diameter of the tool pin [1] is higher than the inside diameter/mating hole of the tube [6] .

It is another object of the present invention, wherein the rotational speed of the spindle [3] is selected from a range of 500 rpm to 2500 rpm.

It is another object of the present invention, wherein the spacer [8] is removable/repositionable to provide an additional plunge to the guide tool [4] .

It is another object of the present invention to provide a method for friction welding of dissimilar tubes comprising:

assembling of the work piece on the machine using the backing block [7] and the spacer [8]; and

rotating and plunging of the guide tool [4] into the workpiece,

wherein the tube plate [5] and the tube [6] are perpendicular to each other, wherein the rotating and plunging causes extrusion of the tube plate [5], wherein the cessation of rotation of the guide tool [4] as the tube [6] and tube plate [5] reaches plastic condition, and

characterized in that a metallurgical bond is formed between the tube [6] and tube plate [5] resulting in transition joint.

It is another object of the present invention, wherein the spacer [8] is removed to provide an additional plunge or suitable mechanism to provide gap to extrude the tube [6] . BRIEF DESCRIPTION OF THE DRAWINGS:

So that the manner in which the features, advantages and objects of the invention, as well as others which will become apparent, may be understood in more detail, more particular description of the invention briefly summarized above may be had by reference to the embodiment thereof which is illustrated in the appended drawings, which form a part of this specification. It is to be noted, however, that the drawings illustrate only a preferred embodiment of the invention and is therefore not to be considered limitation of the invention's scope as it may admit to other equally effective embodiments.

FIG. 1 illustrates the schematic diagram of Friction Welding of Tube to Tube Tool according to one embodiment of the present invention.

FIG. 2 illustrates the sectional view of the friction welding of tube to tube using a guide tool machine according to the present invention.

FIG.3 illustrates a schematic sectional view of the system assembly for friction welding of dissimilar tubes according to another embodiment of the present invention.

FIG.4 illustrates a tube to tube plate welded with the presence of spacer (stage I) according to the present invention.

FIG.5 illustrates a tube to tube plate welded with the absence of spacer (stage II) according to the present invention.

FIG.6 illustrates the sectional view of the removal of the plate of the joint and the transition joint fabrication by friction welding of tube to tube using a guide tool process according to the present invention.

DESCRIPTION FOR DRAWINGS WITH REFERENCE NUMERALS:

[1] Friction Welding of Tube To Tube Tool Pin

[2] Friction Welding of Tube To Tube Tool Shoulder

[3] Spindle

[3 a] Machine Table

[4] Guide tool

[5] Tube Plate (second tube material)

[6] Tube

[7] Backing block

[8] Spacer DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The present disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

The present invention relates to a method for welding tube to tube of different metals/materials. More particularly, the present invention relates to a system an method for friction welding of dissimilar tubes. Advantageously the present invention relates to a guide tool with transition joint designed to weld tube to tube of different metals/materials for different applications.

According to one embodiment of the present invention, a system for friction welding of dissimilar tubes is provided comprising of a guide tool [4] with a pin [1], a shoulder [2] and a spindle [3], a machine table [3a], Guide tool [4] a tube plate of second tube material [5] with a tube [6] and a backing block [7] and a spacer [8]. The guide tool [4] is assembled in a machine comprising of a spindle [3], a machine table [3a] and a tool holder. The guide tool [4] is fixed to the spindle [3] of the machine. The work piece consisting of the tube plate [5] and the tube [6] is assembled in the machine table [3a] using a backing block [7] and the spacer [8]. The tube [6] and tube plate [5] of the workpiece is assembled on the machine table [3a] with the backing block [7] and the spacer [8]. The tube plate [5] and the tube [6] are of different materials/metals. The diameter of the tool pin [1] is higher than the inside diameter/mating hole of the tube [6]. The rotational speed of the spindle [3] is selected from a range of 500 rpm to 2500 rpm. The spacer [8] is removable/repositionable to provide an additional plunge to the guide tool [4].

Referring to Fig.3, a schematic sectional view of the system assembly for friction welding of dissimilar tubes according to another embodiment of the present invention is illustrated. The tool [4] is fixed in the spindle [3] and the work piece consists of tube [6] and a tube plate [5] as shown in the Fig.3. The tube and tube configuration is assembled on the machine table with a backing block [7] and a spacer [8] as shown in the Fig 3. The tool [4] is rotated and plunged in to the assembly and the metal flows in the gap between the pin [1] and the inner diameter of the tube [6]. The spacer [8] is removed by suitable method and additional plunge. The metal flows and the tube [6] is pushed inwards and the tube plate [5] is extruded between the pin [1] and guide block in the form of tube. The spacer [8] is removed after tube welding. The tool [4] is removed and the joint is removed from the backing block [7]. The plate material is removed and the desired transition joint between two dissimilar tubes is achieved. The Tool [4] is given plunge until the tube [6] is supported by the backing block [7]. A transition joint is fabricated between A A 5052 tube and A A 6061 at 1100 rpm.

According to another embodiment of the present invention, a method for friction welding of dissimilar tubes is provided. The work piece is assembled on the machine using the backing block [7] and the spacer [8] . The guide tool [4] is rotated and plunged into the workpiece. The tube plate [6] and the tube [5] are perpendicular to each other. The rotating and plunging causes extrusion of the tube plate [5]. The cessation of rotation of the guide tool [4] as the tube [6] and tube plate [5] reaches plastic condition. A metallurgical bond is formed between the tube [6] and tube plate [5] resulting in transition joint and interference fit. The spacer [8] is removed to provide an additional plunge. The interference fit is a heavy drive fit, light drive fit or shrink fit.

The machine used is having a spindle and rotates at a determined speed. The tool [4] can be plunged in to the work piece. The diameter of tool pin [1] is higher than the inside diameter or mating hole of the tube [6] (i.e. the difference between the tube internal diameter and tool pin diameter is always negative) and the setup of machine is shown in Fig. l. The tool pin [1] is inserted inside the tube [6] before welding. Many techniques are available to obtain interference fit e.g. Heavy drive fit, light drive fit, shrink fit technique etc. The tool [4] is lowered under rotation and heat is generated due to friction. When the plate [5] reaches plastic condition, it offers braking force on the tube [6] and hence tube rotation ceases. Hence, a metallurgical bond is achieved between tube [6] and tube plate [5]. As shown in Fig. 4. The process variables include tool rotational speed, pin clearance and shoulder diameter. The tube to tube pate joint is machined by suitable shape as shown in Fig.4. The transition joint thus achieved can be weld tubes of different metals/ materials for different applications as shown in Fig.6.

The material cost of the friction welding of dissimilar tubes is reduced and the system for friction welding of dissimilar tubes provides improved performance. The process for friction welding of dissimilar tubes is more economical.

Although the invention has been described and illustrated with respect to the exemplary embodiments thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions and additions may be made therein and thereto, without parting from the spirit and scope of the present invention.

Claims

WE CLAIM:

1. A system for friction welding of dissimilar tubes, comprising:

a spacer [8],

wherein the guide tool [4] is assembled in a machine comprising of the spindle [3], the machine table [3 a] and a tool holder,

wherein the guide tool [4] is fixed to the spindle [3] of the machine, wherein the workpiece consisting of the tube plate [5] and the tube [6] is assembled in the machine table [3a] using a backing block [7] and the spacer [8], wherein the tube [6] and tube plate [5] of the workpiece is assembled on the machine table [3a] with the backing block [7] and the spacer [8], and characterized in that the tube plate [5] and the tube [6] are of different materials/metals .

2. The system for friction welding of dissimilar tubes as claimed in claim 1, wherein the rotational speed of the spindle [3] is selected from a range of 500 rpm to 2500 rpm.

3. The system for friction welding of dissimilar tubes as claimed in claim 1, wherein the spacer [8] is removable/repositionable to provide an additional plunge to the guide tool [4].

4. A method for friction welding of dissimilar tubes comprising:

rotating and plunging of the guide tool [4] into the workpiece,

5. The method for friction welding of dissimilar tubes as claimed in claim 4, wherein the spacer [8] is removed to provide an additional plunge or suitable mechanism to provide gap to extrude the tube [6] .