[0001] The present disclosure relates to the field of optical fiber, and in particular, relates to an apparatus having a glass burner for optical fiber glass preform joining and a method of joining the optical fiber glass preform using the glass burner. The present application is based on, and claims priority from an Indian Application Number 202011023697 filed on 05-06-2020, the disclosure of which is incorporated herein.

BACKGROUND
[0002] With the advancement of science and technology, various modern technologies are being employed for communication purposes. One of the most important modern communication technologies is optical fiber communication technology using a variety of optical fiber cables. The optical fiber cables are widely used for communication to meet increasing demands. Manufacturing of optical fibers for the optical fiber cables at a rapid pace becomes essential. The optical fibers are manufactured from a quartz-based glass matrix. The quartz-based glass matrix is made using a plurality of techniques. The plurality of techniques includes a vapour-phase axial deposition (VAD) technique, an outside vapour deposition technique (OVD), and the like. The quartz-based glass matrix is dehydrated and sintered to obtain a glass fiber ingot. The glass fiber ingot is processed into an optical fiber glass preform using an electric furnace. The optical fiber glass preform is drawn into a drawing furnace to obtain the optical fibers using a fiber drawing method. The optical fiber glass preform is subsequently subjected to heat treatment process before being drawn into the drawing furnace. The heat treatment process is used for a plurality of objectives.
[0003] The plurality of objectives includes joining optical fiber glass preforms in less time with reduced cracks and gas bubbles into the optical fiber preform, an improved quality of joined optical fiber preform and an improvement in uptime during joining of the optical fiber preform. Another objective is joining the optical fiber glass preforms having a sufficient mixture of flame obtained from flammable and supporting gases so that flame is laminar in form and thus overheating can be avoided. The method of preform joining is cost effective since supporting and flammable gases are consumed less due to having a sufficient proportion required for joining glass preform and the like. Usually, a single optical fiber glass preform drawing is carried out in a draw tower. The single optical fiber glass preform drawing leads to frequent changeovers and furnace exposure happens at every changeover due to which performance of the drawing furnace in the draw tower may deteriorate and chances of bare fiber diameter (BFD) draw breaks and airlines defects may increase. These defects lead to short length generation of the optical fibers and increase in optical fiber scrap. To reduce time and improve the drawing process efficiency, joining of the optical fiber glass preforms is carried out with burners. The burners are made of quartz or metal. A supporting gas and a flammable gas are supplied in the burners for heat treatment of the optical fiber glass preform. Generally, the supporting gas includes oxygen and the flammable gas includes hydrogen, methane, propane, and the like.
[0004] However, conventional burners are inefficient to mix the supporting gas and the flammable gas in an appropriate proportion that results in overheating. In addition, the conventional burners are incapable to provide high heating power for preform joining without any presence of gas bubbles and cracks. This further degrades the quality of the optical fiber glass preform. Further, the conventional burners have limited jet capillaries that result in insufficient flame ratio. Furthermore, the conventional burners have turbulent flames. Moreover, conventional burners have varying flame temperature profile. Also, the conventional burners have varying heat distribution across the surface of the optical fiber glass preform. The conventional burners, that are used to provide flame for joining the optical fiber glass preforms, are not able to provide high heating power due to which cracks or gas bubbles form inside the optical fiber glass preform while joining, which results into lower quality of joined optical fiber glass preform. Further, due to low heat resistance of the conventional burners, the materials such as metal used in the conventional burners melt and enter into the optical fiber glass preform in form of impurities, thereby resulting into degradation of optical properties of the optical fiber glass preform.
[0005] The conventional burners used to join optical fiber (glass) preforms that are usually convex shaped. Machining convex shape at one end of the optical fiber glass preform is an expensive process. Since conventional burners have insufficient mixture of supporting and flammable gas that leads to turbulent flame which rather than used completely for joining of preform was being wasted as overheating.
[0006] For example, a prior art JP2005145796A discloses a metal burner for joining preform having end surfaces in convex shape. The metal burner has a disadvantage that due to low heat resistance, the metal burner gets melted and few chunks of the metal burner falls into the preform during the joining process and thus adds an impurity in the preform. Also, the convex shape at end surfaces of the preform results in an expensive process. Major limitation of this being low heating power of the metal burner and thereby causing crack and gas bubble into the preform that has to be join.
[0007] In light of the above-stated discussion, there exists a need for a burner that overcomes the above cited drawbacks of the conventional burners.

OBJECT OF THE DISCLOSURE
[0008] A primary object of the present disclosure is to provide a method of joining optical fiber glass preforms using a burner (or a glass burner).
[0009] Another object of the present disclosure is to provide the burner for increasing preform joining capacity.
[0010] Another object of the present disclosure is to provide the burner with reduced consumption of supporting gas and flammable gas.
[0011] Yet another object of the present disclosure is to provide the burner with additional capillaries to avoid overheating inside the burner and working space that are involved in joining of the optical fiber glass preforms.
[0012] Yet another object of the present disclosure is to provide uptime improvement i.e., reducing time taken by the burner for preform joining.

SUMMARY
[0013] In an aspect, a method of joining a first cylindrical body and a second cylindrical body using a burner is disclosed. The burner is a quartz glass burner. The first cylindrical body and the second cylindrical body are used for manufacturing an optical fiber. The first cylindrical body and the second cylindrical body have a protruded central cylindrical region surrounded by one or more concentric base regions. The one or more concentric base regions prevent the protruded central cylindrical region of the cylindrical body from atmospheric interference like dust etc.
[0014] The method of joining of two cylindrical bodies i.e., the first cylindrical body and the second cylindrical body using the burner includes aligning the first cylindrical body and the second cylindrical body along a longitudinal axis passing through centres of the first cylindrical body and the second cylindrical body. The first cylindrical body and the second cylindrical body have the protruded central cylindrical region surrounded by one or more concentric base regions, wherein the first cylindrical body and the second cylindrical body are aligned such that the protruded central cylindrical region of the first cylindrical body and the protruded central cylindrical region of the second cylindrical body are separated by a first predefined distance. Heating is provided to the first cylindrical body and the second cylindrical body prior to melting to initiate softening of the first cylindrical body and the second cylindrical body (i.e., glass preforms) so that they can be melted and fused together to complete the joining process of the two cylindrical bodies. The first cylindrical body and the second cylindrical body are being rotated and heated simultaneously, wherein a relative rotational motion between the first cylindrical body and the second cylindrical body is zero to prevent misalignment while the preform joining is under process. The first cylindrical body and the second cylindrical body are being rotated along the longitudinal axis in a clockwise direction or in a counter-clockwise direction with a constant speed so that it is always away from the worker standing position for safety. The distance between the first cylindrical body and the second cylindrical body continuously reduces from the first predefined distance to a second predefined distance starting from 20 centimeters to 2 centimeters. Further, the method includes melting the protruded central cylindrical region and the one or more concentric base regions of the first cylindrical body and the second cylindrical body. Furthermore, the method includes joining the first cylindrical body with the second cylindrical body using the burner to achieve the joined preform having no presence of crack and gas bubble into the joined cylindrical body (preform).
[0015] In another aspect, a cylindrical body (preform) joining apparatus for joining the first cylindrical body and the second cylindrical body is disclosed. The cylindrical body joining apparatus comprises a gripping mechanism for holding the first cylindrical body and the second cylindrical body. The first cylindrical body and the second cylindrical body is gripped with the help of four jaw chuck present in a tailstock and a headstock in a lathe. The four jaw chuck is made of stainless steel and is corrosive resistance. Further, the gripping mechanism assists the first cylindrical body and the second cylindrical body to be aligned in front of each other along a longitudinal axis that passes through centers of the first cylindrical body and the second cylindrical body. The alignment is done in such a way that end surfaces (first end and second end) of the first cylindrical body and the second cylindrical body having the protruded central cylindrical region and the one or more concentric base regions, face each other and separated by a first predefined distance between them. Further, the gripping mechanism is attached to a rotating mechanism. The rotating mechanism imparts rotation to the first cylindrical body and the second cylindrical body such that a relative motion between the first cylindrical body and the second cylindrical body is zero. The burner (or glass burner) is arranged on a suitable place on the lathe that heats and melts the first cylindrical body and the second cylindrical body while the first cylindrical body and the second cylindrical body are in rotational motion and simultaneously sliding via a sliding mechanism, towards each other for fusion. The sliding mechanism has guideways and is present on the lathe. The sliding mechanism due to a chuck, imparts to and fro movement to the first cylindrical body and the second cylindrical body. Due to the sliding mechanism, the first predefined distance between them is continuously decreasing until both cylindrical bodies fuses to become a fused joined cylindrical body.
[0016] The burner, that is made of quartz glass, withstands high temperature during the joining process of cylindrical bodies that is 1550-1600 degree Celsius. The burner has a funnel-like structure consisting of a plurality of capillary tubes (or tubes or jet capillaries) for the flammable gas and a space around the plurality of capillary tubes for supporting gas so as to melt the protruded central cylindrical regions and the one or more concentric base regions of the first cylindrical body and the second cylindrical body. An inlet for the supporting gas, such as oxygen, is situated at bottom of the burner and thus has a bottom entry. While an inlet for the flammable gas, such as hydrogen, is situated at outer side of the burner and thus has a side entry. The supporting gas passes through the plurality of capillary tubes. While the flammable gas passes through a funnel-like outer tube between the plurality of capillary tubes. The burner joins the first cylindrical body and the second cylindrical body by providing high heating power having laminar flow flame structure with an increased flow of the gases in a predetermined ratio of 2:1 for hydrogen and oxygen gas respectively so as to provide sufficient mixing of the gases. The laminar flow flame structure implies focused flame. Laminar flame provides advantages like reducing consumption of flammable and supporting gases and preventing overheating of the burner during preform joining thereby reducing time taken by the first cylindrical body and the second cylindrical body to join.
[0017] These and other aspects herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the invention herein without departing from the spirit thereof.

BRIEF DESCRIPTION OF FIGURES
[0018] The invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the drawings. The invention herein will be better understood from the following description with reference to the drawings, in which:
[0019] FIG. 1 illustrates a close view of a burner.
[0020] FIG. 2 illustrates a cross sectional view of the burner.
[0021] FIG. 3 illustrates a front view of the burner having an oxygen gas injector and a hydrogen gas injector.
[0022] FIG. 4 illustrates a front view of an end surface of a cylindrical body having a protruded central cylindrical region.
[0023] FIG. 5 illustrates a side view of the cylindrical body having the protruded central cylindrical region.
[0024] FIG. 6 illustrates an apparatus for joining two cylindrical bodies.
[0025] FIG. 7 is a flow chart illustrating a method of joining a first cylindrical body and a second cylindrical body using the burner.

DETAILED DESCRIPTION
[0026] In the following detailed description of the invention, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be obvious to a person skilled in the art that the invention may be practiced with or without these specific details. In other instances, well known methods, procedures and components have not been described in details so as not to unnecessarily obscure aspects of the invention.
[0027] Furthermore, it will be clear that the invention is not limited to these alternatives only. Numerous modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art, without parting from the scope of the invention.
[0028] The accompanying drawings are used to help easily understand various technical features and it should be understood that the alternatives presented herein are not limited by the accompanying drawings. As such, the present disclosure should be construed to extend to any alterations, equivalents and substitutes in addition to those which are particularly set out in the accompanying drawings. Although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are generally only used to distinguish one element from another.
[0029] FIG. 1 illustrates a close view of a burner (100). FIG. 2 illustrates a cross sectional view of the burner (100). FIG. 3 illustrates a front view of the burner (100) having an oxygen gas injector and a hydrogen gas injector. FIG. 4 illustrates a front view of an end surface of a cylindrical body (500). The cylindrical body (500) has a protruded central cylindrical region (501) and one or more concentric base regions (502). The cylindrical body (500) is preferably a glass body or an optical fiber glass preform. FIG. 5 illustrates a side view of the cylindrical body having the protruded central cylindrical region. The burner (100) is used for joining two cylindrical bodies. The burner (100) is made of a quartz glass. The quartz glass is resistant to high temperature. Due to high temperature resistance of the quartz glass, the burner material does not get mixed into the cylindrical body as impurities during the joining process of the two cylindrical bodies and thus it does not degrade the properties of the cylindrical body like low heat resistant material based conventional burners. Further, the quartz glass has a high corrosive resistance and a low coefficient of thermal expansion. The burner (100) may also be referred to as a glass burner (100).
[0030] Alternatively, the burner (100) is made of any suitable material. The burner (100) has a cylindrical structure. Alternatively, structure of the burner (100) may vary. The burner has a pitch circle diameter of 17 millimeter, which is an inner diameter of a funnel-like outer tube (104). The pitch circle diameter being less than 17 millimeter will not allow joining of the two cylindrical bodies as a plurality of capillary tubes (106) will not be able to placed inside the burner (100) and beyond 17 millimeter, there may be overheating in the burner due to presence of more space for hydrogen and will have an impact on safety of the workers. The burner (100) increases capacity for joining of the two cylindrical bodies. The joining capacity for the two cylindrical bodies is based on time taken for joining the two cylindrical bodies and mixing of flammable gas and supporting gas used for a process of joining the two cylindrical bodies. The plurality of capillary tubes (106) (or plurality of tubes or plurality of jet capillaries) may be 12 in number and so have a same number of nozzles (108) for passing the supporting gas i.e., oxygen gas. Alternatively, the plurality of capillary tubes (106) inside the burner may vary. While the flammable gas, i.e., hydrogen gas, passes/flows through a funnel like structure of the burner between the plurality of capillary tubes (106). This arrangement provides sufficient mixing of oxyhydrogen gas and reduces time taken for completion of the joining process of the two cylindrical bodies. In addition, the burner (100) provides a high work efficiency.
[0031] The burner (100) decreases temperature irregularities of a flame and provides uniform heat or excellent flame ratio across surface of the burner (100). Such uniform heat or excellent flame ratio is achieved by the plurality of capillary tubes (106) (as shown in FIG. 1, FIG. 2 and FIG. 3) of the burner (100) giving more passage to oxygen gas to flow and hence is providing sufficient mixture of oxyhydrogen gas. The flame structure from the burner is laminar since more passage has been provided for oxygen gas through the plurality of capillary tubes (106). The burner (100) enables constant flow of oxyhydrogen gas. The flow of oxyhydrogen gas from the burner (100) is increased gradually that further implies that flow varies for both oxygen and hydrogen gases at different points of time. The maximum limit in flow of oxygen and hydrogen gases are 180 and 380 slpm (standard litre per minute) respectively. The burner utilizes oxyhydrogen gas for enabling oxidation and melting during the joining process of the two cylindrical bodies. The burner (100) maintains a uniform flame temperature profile, which is achieved by gradual increase in flow for oxyhydrogen gas. Further, the burner (100) converts turbulent flame into the laminar flame. In general, the turbulent flame refers to flame with irregular and haphazard flow and the laminar flame refers to flame with a smooth uniform flow. The laminar flame structure results in sufficient mixture of oxyhydrogen gases and leads to high heating power, thereby resulting in quick joining without any gas bubble and crack into a joined cylindrical body. The joined cylindrical body is achieved of high quality as there are almost zero gas bubble or crack formed into the joined cylindrical body. Moreover, the burner (100) reduces machine cycle time for joining of the two cylindrical bodies. The machine cycle time implies time taken for joining of the two cylindrical bodies by the glass burner. The machine cycle time for joining of the two cylindrical bodies is about 20 minutes. In an example, the burner (100) is utilized continuously for a time period of about 10 to 15 hours for joining the two cylindrical bodies. In the time period of about 10 to 15 hours, usually 16 to 20 cylindrical bodies may be joined that depicts high working efficiency of the burner (100). The burner (100) easily joins the cylindrical bodies having a diameter of about 130 to 180 millimeters as below 130 millimeters there will be a reduction in fiber per kilometer or reduction in volume of manufactured fiber from the joined preform, whereas above 180 millimeters, joining process will require a high heating power.
[0032] Referring to FIG. 4 and FIG. 5, the cylindrical body (500) has the protruded central cylindrical region (501) surrounded by the one or more concentric base regions (502). The protruded central cylindrical region (501) is silica doped with germanium. The protruded central cylindrical region (501) of the cylindrical body (500) has a protruded region at one end. The protruded central cylindrical region (501) has a length of about 25mm±5mm, below which more heat will be required to avoid gas bubble formation and beyond this range gas bubble will be formed faster and thus it will become impossible to control the joining process of the two cylindrical bodies. Further, the protruded central cylindrical region (501) has a diameter of 9mm±0.5mm, below which more heat will be required to avoid gas bubble formation and beyond this range gas bubble will be formed faster and thus it will become impossible to control the joining process of the two cylindrical bodies. The protruded central cylindrical region (501) may have a circular surface or a convex surface. Since machining of convex surface is a highly expensive process, the protruded central cylindrical region (501) mostly has a circular surface. The cylindrical body undergoes rotational cutting in an axial direction. The cylindrical body is cut in 90 degree that is an L-shaped cut as shown in FIG. 5 from the one or more concentric base regions (502) to a central cylindrical region up to that point only where diameter of the cylindrical body is half so that the central cylindrical region is at the middle and does not get disturbed and thus the protruded central cylindrical region (501) is formed on the cylindrical body (500). The protruded central cylindrical region of the cylindrical body prevents air gaps and thus eliminates the formation of gas bubble and cracks into the cylindrical body during the joining process.
[0033] Provided that the optimum length and diameter of the protruded central cylindrical region (or protruded core) of the cylindrical body is maintained with the diameter of about 130-180mm, the joining can be achieved with sufficient heating without degrading the properties of the cylindrical body.
[0034] Referring to FIG. 1, FIG. 2, and FIG. 3, the burner (100) includes the funnel-like outer tube (104), the plurality of capillary tubes (106), the hydrogen gas injector (109) and the oxygen gas injector (107). The funnel-like outer tube (104) of the burner has a funnel-like structure consisting of the plurality of capillary tubes (106) and a plurality of inlets for the supporting gas and the flammable gas so as to melt the central cylindrical region and the one or more concentric base regions of a first cylindrical body and a second cylindrical body. An inlet for the supporting gas, such as oxygen gas, is located at bottom of the burner and thus has a bottom entry. Further, an inlet for the flammable gas, such as hydrogen gas, is situated at outer side of the burner and thus has a side entry. The supporting gas passes through the plurality of capillary tubes (106) and the flammable gas passes through the funnel-like outer tube (104) between the plurality of capillary tubes (106). The plurality of capillary tubes (106) prevents overheating inside the burner (100). In addition, the plurality of capillary tubes (106) prevents overheating inside machines that are involved in performing joining of the two cylindrical bodies. Each of the plurality of capillary tubes (106) has hollow structure and is positioned parallel to a geometrical center (110) (as shown in FIG. 3) of the funnel-like outer tube (104) of the burner (100). The geometrical center (110) is a midpoint of the funnel-like outer tube (104) of the burner (100). The funnel-like outer tube (104) has a diameter greater than a diameter of the plurality of capillary tubes present inside the burner. In an example, number of the plurality of capillary tubes (106) in the burner (100) is 12. Alternatively, the number of the plurality of capillary tubes (106) in the burner (100) may vary. The plurality of capillary tubes (106) corresponds to jet capillaries. Each of the plurality of capillary tubes (106) has an inner radius and an outer radius. The inner radius of each of the plurality of capillary tubes (106) is about 0.0015 to 0.0025 meters. The inner radius of each of the plurality of capillary tubes (106) below 0.0015 meters is not possible as it is prescribed under ITU standard (International Telecommunication Unit) and beyond 0.0025 meters, release of oxygen flow increases and cools down the two cylindrical bodies and thus it becomes impossible to join the two cylindrical bodies. The outer radius of each of the plurality of capillary tubes (106) is about 0.002-0.005 millimeter, wherein below 0.002 millimeter, the outer radius is not possible as per ITU standard and beyond 0.005 millimeter, the release of oxygen will increase which will actually cool the two cylindrical bodies and thus it will become impossible to join them. Further, each of the plurality of capillary tubes (106) has an area of 0.00001 square meter. Alternatively, the area of each of the plurality of capillary tubes (106) may vary.
[0035] Each of the plurality of capillary tubes (106) has a nozzle (108) at tip of each of the plurality of capillary tubes (106). That is, the plurality of capillary tubes (106) has a plurality of nozzles (108). In general, the nozzle controls flow rate, speed, direction, mass, shape, and/or pressure of the flammable gas and the supporting gas emerging from the nozzle (108). In an example, the nozzle (108) has an open end that directs flow of the flammable gas and the supporting gas into the burner (100). In another example, the nozzle (108) intends to eject the flammable gas and the supporting gas in the burner (100).
[0036] The nozzle (108) of each of the plurality of capillary tubes (106) lies in the funnel-like outer tube (104) of the burner (100). The funnel-like outer tube (104) provides housing to the nozzle (108) of each of the plurality of capillary tubes (106). The funnel-like outer tube (104) is circular in shape. The funnel-like outer tube (104) has a radius of about 0.007 to 0.009 meter, as the radius below this range is not possible as per ITU standards and beyond this range, release of hydrogen increases that actually increases turbulent nature of the flame from the burner. Further, the funnel-like outer tube (104) has a diameter of 0.013 to 0.017 meter and is called as pitch diameter, wherein the diameter below this range is not possible as per ITU standards and beyond this range, release of hydrogen increases that further increases the turbulent nature of the flame from the burner. The funnel-like outer tube (104) has an area of 0.00014 square meter. Alternatively, the area of the funnel-like outer tube (104) may vary.
[0037] Referring to FIG. 3, the burner (100) includes a flammable gas injector and a supporting gas injector i.e., the hydrogen gas injector (109) and the oxygen gas injector (107) respectively. The inlet for hydrogen gas is situated at outer side of the burner (100) and thus has the side entry. The hydrogen gas injector (109) is used to inject hydrogen gas in the burner (100). The flammable gas i.e., hydrogen passes through the funnel-like outer tube (104) between the plurality of capillary tubes (106). The hydrogen gas is injected in the burner (100) to increase energy efficiency of the burner (100) and to reduce emission of carbon dioxide from the burner (100) into atmosphere. The hydrogen gas flows in the plurality of capillary tubes (106) of the burner (100). The hydrogen gas injector (109) may be connected with the funnel-like outer tube (104) of the burner (100). The burner (100) reduces consumption of hydrogen gas while performing joining of the two cylindrical bodies as cycle time in joining of the two cylindrical bodies through the burner (glass burner) reduces from 180 minutes to 20 minutes. Earlier through conventional methods, the time taken for joining of the two cylindrical bodies with the help of the burner was 180 minutes since burner was not able to provide high heating power to the cylindrical bodies for joining. An amount of hydrogen gas consumed in the burner (100) during joining of the two cylindrical bodies is about 12.6 cubic meter. Alternatively, the amount of hydrogen gas consumed in the burner (100) during joining of the two cylindrical bodies is about 13 cubic meter. Alternatively, the amount of hydrogen gas consumed in the burner (100) during joining of the two cylindrical bodies may vary.
[0038] Further, the hydrogen gas in the burner (100) has a velocity of about 606.55 to 636.62 meter per second, below which, the burner will blow off due to increase in pressure and beyond which, there will be insufficient mixture of oxyhydrogen gas thus there will be insufficient heating. Alternatively, the range of velocity of hydrogen gas in the burner (100) may vary depending upon the size of the cylindrical bodies and the number of capillary tubes in such a way that the ratio of H2 and O2 (i.e., H2:O2) is 2:1. The velocity of hydrogen gas depends on an area of flow of hydrogen gas. The velocity of hydrogen gas in the burner (100) reduces as the area of flow of hydrogen gas increases. The hydrogen gas injector (109) has a diameter in a range of 8+0.5 millimeter as per standard fittings in the burner. Further, the hydrogen gas flows in the burner (100) in the area of 0.00001 square meter. Alternatively, the area for flow of hydrogen gas in the burner (100) may vary depending upon the size of the cylindrical bodies and the number of capillary tubes in such a way that the ratio of H2 and O2 (i.e., H2:O2) is 2:1. Furthermore, a Reynolds number for hydrogen gas in the burner (100) is in a range of 6250 to 6474, below which, there may be safety issues as the burner may blow off, whereas beyond this range, there will be insufficient heating for joining of the two cylindrical bodies. Alternatively, the range of Reynolds number for the hydrogen gas in the burner (100) may vary depending upon the size of the cylindrical bodies and the number of capillary tubes in such a way that the ratio of H2 and O2 (i.e., H2:O2) is 2:1. The flow rate of the hydrogen gas in the burner (100) is 330 to 380 standard liters per minute (slpm) as below 330 slpm, there will be insufficient heating and beyond 380 slpm, the burner may blow off. Alternatively, the range of the flow rate of the hydrogen gas in the burner (100) may vary depending upon the size of the cylindrical bodies and the number of capillary tubes in such a way that the ratio of H2 and O2 (i.e., H2:O2) is 2:1. The hydrogen gas flows in the plurality of capillary tubes (106) at flow rate (Q) of 0.0060 to 0.0080 cubic meter per second. Below 0.0060 cubic meter per second, there may be insufficient heating for joining of the two cylindrical bodies and beyond 0.0080 cubic meter per second, there may be safety issues since gas burner may blow off. Alternatively, the range of the flow rate (Q) of hydrogen gas in the plurality of capillary tubes (106) may vary depending upon the size of the cylindrical bodies and the number of capillary tubes in such a way that the ratio of H2 and O2 (i.e., H2:O2) is 2:1.
[0039] The oxygen gas injector (107) injects oxygen gas in the burner (100). The inlet for the supporting gas, i.e., the oxygen gas is situated at the bottom of the burner (100) and thus has the bottom entry. The oxygen gas passes through the plurality of capillary tubes (106). The oxygen gas injector (107) has a diameter of 0.0080 to 0.0091 meter as per standard fitting range for the burner. Alternatively, the diameter of the oxygen gas injector (107) may vary depending upon the size of the cylindrical bodies and the number of capillary tubes in such a way that the ratio of H2 and O2 (i.e., H2:O2) is 2:1. The oxygen gas flows in the funnel-like outer tube (104) of the burner (100). In general, oxygen gas reduces fuel consumption and provides fast melting. A flow rate of the oxygen gas in the burner (100) is about 150 standard liters per minute. Alternatively, the flow rate of the oxygen gas in the burner (100) may vary depending upon the size of the cylindrical bodies and the number of capillary tubes in such a way that the ratio of H2 and O2 (i.e., H2:O2) is 2:1. The oxygen gas flows from the plurality of capillary tubes (106) having the plurality of nozzles (108) at its tip. That is, each of the plurality of capillary tubes (106) has one nozzle (108) from which the oxygen gas flows. The oxygen gas flows from the plurality of capillary tubes (106) at a flow rate (Q) of 0.0015 to 0.0025 cubic meter per second, wherein below 0.0015 cubic meter per second, there may be insufficient heating for joining of the two cylindrical bodies and beyond 0.0025 cubic meter per second, the burner may blow off, thus there may be safety issues. Alternatively, the range of the flow rate (Q) of oxygen gas may vary depending upon the size of the cylindrical bodies and the number of capillary tubes in such a way that the ratio of H2 and O2 (i.e., H2:O2) is 2:1.
[0040] The oxygen gas in the burner (100) has a velocity of about 40.450 to 42.870 meter per second, below which, pressure may get high that may blow off the burner and may lead to safety issues and beyond this, insufficient heating will be there for preform joining. Alternatively, the velocity of the oxygen gas in the burner (100) may vary depending upon the size of the cylindrical bodies and the number of capillary tubes in such a way that the ratio of H2 and O2 (i.e., H2:O2) is 2:1. The velocity of the oxygen gas depends on an area of flow of oxygen gas. The velocity of the oxygen gas in the burner (100) reduces as the area of flow of oxygen gas increases. The oxygen gas flows in the burner (100) in an area of 0.00006 square meter. Alternatively, the area for flow of oxygen gas in the burner (100) may vary depending upon the size of the cylindrical bodies, the number of capillaries tubes in such a way that the ratio of H2 and O2 (i.e., H2:O2) is 2:1. A Reynolds number for oxygen gas in the burner (100) is 22892 to 25734, below which, there will be turbulence in the flame i.e., insufficient heating for proper joining of the two cylindrical bodies and beyond which, the burner may get blown off thus leading to safety issues. Alternatively, the range of the Reynolds number for oxygen gas in the burner (100) may vary depending upon the size of the cylindrical bodies and the number of capillaries tubes in such a way that the ratio of H2 and O2 (i.e., H2:O2) is 2:1. The burner (100) reduces consumption of the oxygen gas while performing joining of the two cylindrical bodies. An amount of oxygen gas consumed in the burner (100) during joining of the two cylindrical bodies is about 6 cubic meters. Alternatively, the amount of oxygen gas consumed in the burner (100) during joining of the two cylindrical bodies may vary depending upon the size of the cylindrical bodies and the number of capillaries tubes in such a way that the ratio of H2 and O2 (i.e., H2:O2) is 2:1.
[0041] FIG. 6 is a cylindrical body (preform) joining apparatus (600) for joining a first cylindrical body and a second cylindrical body. The cylindrical body joining apparatus (600) comprises a gripping mechanism (602) for holding the first cylindrical body and the second cylindrical body. The first cylindrical body and the second cylindrical body is gripped with the help of four jaw chuck present in a tailstock and a headstock in a lathe (608). The four jaw chuck is made of stainless steel and is corrosive resistance. Further, the gripping mechanism (602) assists the first cylindrical body and the second cylindrical body to be aligned in front of each other along a longitudinal axis that passes through centers of the first cylindrical body and the second cylindrical body. The alignment is done in such a way that end surfaces (first end and second end) of the first cylindrical body and the second cylindrical body having the protruded central cylindrical region and the one or more concentric base regions, face each other and separated by a first predefined distance between them. Further, the gripping mechanism (602) is attached to a rotating mechanism (606). The rotating mechanism imparts rotation to the first cylindrical body and the second cylindrical body such that a relative motion between the first cylindrical body and the second cylindrical body is zero. The burner (or glass burner) (100) is arranged on a suitable place on the lathe (608) that heats and melts the first cylindrical body and the second cylindrical body while the first cylindrical body and the second cylindrical body are in rotational motion and simultaneously sliding via a sliding mechanism (604), towards each other for fusion. The sliding mechanism has guideways and is present on the lathe (608). The sliding mechanism due to a chuck, imparts to and fro movement to the first cylindrical body and the second cylindrical body. Due to the sliding mechanism (604), the first predefined distance between them is continuously decreasing until both cylindrical bodies fuses to become a fused joined cylindrical body.
[0042] FIG. 7 is a flow chart (700) illustrating a method of joining the two cylindrical bodies (the first cylindrical body and the second cylindrical body) using the burner (100).
[0043] At step (702), the first cylindrical body and the second cylindrical body are aligned in front of each other by a gripping mechanism (602) along a longitudinal axis that passes through centers of the first cylindrical body and the second cylindrical body. The alignment is done in such a way that end surfaces of the first cylindrical body and the second cylindrical body having the protruded central cylindrical region (501) face each other and separated by a first predefined distance between them. The alignment of the first cylindrical body and the second cylindrical body is carried out on the lathe (608) that is equipped with the burner (100). The first predefined distance between the first cylindrical body and the second cylindrical body is about 20 centimeters initially and is gradually reduced to a second predefined distance i.e., 2 centimeters. This reduction in distance from 20 to 2 centimeter is an optimum distance for joining the two cylindrical bodies.
[0044] At step (704), the first cylindrical body and the second cylindrical body are being rotated by a rotating mechanism (606) along the longitudinal axis in a clockwise direction or in a counter clockwise direction with a constant speed in such a way that it is always rotating away from the worker’s position to stand for their safety purposes and heated with the burner (100) simultaneously to achieve softening of the two cylindrical bodies. A relative rotational motion between the first cylindrical body and the second cylindrical body is zero to avoid misalignment while joining of the two cylindrical bodies is under process. This heating of the end surfaces of the two cylindrical bodies is for the purpose of softening of the first cylindrical body and the second cylindrical body. The burner (100) heats each of the protruded central cylindrical region of the first cylindrical body and the second cylindrical body with an oxyhydrogen flame produced by the burner (100) while the first predefined distance between the first cylindrical body and the second cylindrical body is continuously reducing with the use of the sliding mechanism (604), starting from 20 centimetres to 2 centimetres. The first predefined distance between the two cylindrical bodies can either be reduced with a difference of 2 centimeters i.e., 20 centimeters to 18 centimeters to 16 centimeters and so on and so forth or it may be reduced with a difference of 4 centimeters. The difference may vary. The flow rate of the oxygen gas and the flow rate of the hydrogen gas for the oxyhydrogen flame are increased with a difference of 50 standard liter per minute i.e., from 10 standard liter per minute to 60 standard liter per minute to 110 standard liter per minute and so on and so forth or it may be increased with difference of 40 standard liter per minute. The flow rate of the hydrogen gas is increased at most at 380 standard liter per minute and the flow rate of the oxygen gas is increased at most at 180 standard liter per minute i.e., so as to maintain a ratio of 1:2 (O2:H2) for producing sufficiently mixed oxyhydrogen flame for joining the two cylindrical bodies.
[0045] At step (706), as the first predefined distance between the first cylindrical body and the second cylindrical body decreases to 2 centimeters, the heated protruded central cylindrical region and the one or more concentric base regions of the first cylindrical body and the second cylindrical body undergoes melting that enables the end surfaces of two cylindrical bodies to melt. The first predefined distance between the first cylindrical body and the second cylindrical body is reduced from 20cm to 2cm, as reducing the distance enables uniform melting and efficient joining of the two cylindrical bodies. The burner (100) melts each of the protruded central cylindrical region and the one or more concentric base regions of the first cylindrical body and the second cylindrical body with the oxyhydrogen flame produced by the burner (100).
[0046] The temperature of the oxyhydrogen flame is about 1550 to 1600 Celsius, which is an optimum range for the first cylindrical body and the second cylindrical body to be joined. There may be a relative motion between the burner and the first cylindrical body and the second cylindrical body so that if one surface of the first cylindrical body and the second cylindrical body is not getting enough heat, then it can get so, so as to melt them. The protruded central cylindrical region of the first cylindrical body and the second cylindrical body melts. That is, the protruded central cylindrical regions of the first cylindrical body and the second cylindrical body start fusing initially as the protruded central cylindrical regions are silica doped with germanium (Ge) and gradually the one or more concentric base regions of the first cylindrical body and the second cylindrical body fuse.
[0047] At step (708), the melted first cylindrical body and the second cylindrical body are joined such that the protruded central cylindrical region of the first cylindrical body joins with the protruded central cylindrical region of the second cylindrical body to form a fused joined cylindrical body. As the first predefined distance between the first cylindrical body and the second cylindrical body is reduced to the second predefined distance i.e., 2 centimeters and the flow rate of the oxygen gas and the flow rate of the hydrogen gas is maximum i.e., 180 standard liter per minute and 380 standard liter per minute respectively, a hazy region, generally white region, appears in the oxyhydrogen flame that implies that first cylindrical body and the second cylindrical body are ready to fuse together to join with each other. Flow of hydrogen and oxygen gas is 380 slpm and 180 slpm respectively below which joining of the two cylindrical bodies will take more time and above which it will impact safety due to high increase in temperature. While the first cylindrical body and the second cylindrical body are fused to achieve the fused joined cylindrical body, for proper alignment of diameter of the first cylindrical body and the second cylindrical body, welding can be done, if required.
[0048] The present invention has various advantages over the prior art. The present invention provides highly efficient quartz glass burner (or burner) for joining the two cylindrical bodies. The burner prevents overheating of the cylindrical body and the working space, where the process of joining of the two cylindrical bodies is taking place. In addition, the burner reduces consumption of the hydrogen gas and the oxygen gas during joining of the two cylindrical bodies. The reduced consumption of hydrogen gas and oxygen gas leads to reduction in overall cost of the joining process of the two cylindrical bodies. For example, the overall hydrogen consumption reduced from 37.8 cubic meters to 12.6 cubic meters and oxygen consumption reduced from 18 cubic meters to 6 cubic meters with the help of a 12-capillary tubes (or 12-jet capillaries) quartz glass burner. The burner (100) provides a uniform temperature profile for joining of two cylindrical bodies due to presence of 12-jet capillaries in the burner which thereby provides more space for oxygen gas to flow from the nozzles of the capillary tubes and hence providing sufficient mixture of oxyhydrogen gas for joining of two cylindrical bodies. Thus, the burner provides uniform heat distribution across a surface of the cylindrical body. Advantageously, the unique burner design has a reduced exit velocity of 636 m/s in comparison to the conventional burner exit velocity of about 1091 m/s due to presence of 12-jet capillary tubes thus providing more space for oxygen gas to flow to provide sufficient mixture of oxyhydrogen gases for joining of the two cylindrical bodies. Moreover, the overall Reynold’s number is also reduced in comparison to conventional burners. The cylindrical body has no gas bubbles or cracks into it after joining due to high heating power through 12-jet capillary tubes into the glass burner.
[0049] In an example, the cylindrical body (500) may be an optical fiber glass preform (hereinafter optical fiber glass preform is referred to as preform). The preform is the cylindrical body from which an optical fiber is drawn using a drawing furnace. The preform has the protruded central cylindrical region forming a core of the optical fiber and has the one or more concentric base regions forming a cladding of the optical fiber. The optical fiber is manufactured by initially manufacturing the preform. The preform is pulled in a draw tower in a drawing machine to form the optical fiber. The optical fiber is used for transmitting information as light pulses from one end to another. In general, the optical fiber is a thin strand of glass or plastic capable of transmitting optical signals. In addition, the optical fiber allows transmission of information in the form of optical signals over long distances. The burner (100) easily joins the two preforms having a diameter of about 130 to 180 millimeters, as below 130 millimeters there will be a reduction in fiber per kilometer or reduction in volume of manufactured fiber from the joined preform, whereas above 180 millimeters, joining process will require a high heating power.
[0050] Further, the preform drawing process post joining of the preforms enhances the efficiency of the drawing process. Further, draw towers for the preform drawing may run continuously and overall uptime is improved that results into reduction in optical fiber scrap. Furthermore, the optical fiber drawn from the fused joined preform has reduced attenuation.
[0051] The various actions, acts, blocks, steps, or the like in the flow chart (600) may be performed in the order presented, in a different order or simultaneously. Further, in some implementations, some of the actions, acts, blocks, steps, or the like may be omitted, added, modified, skipped, or the like without departing from the scope of the invention.
[0052] Conditional language used herein, such as, among others, "can," "may," "might," "may," “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain alternatives include, while other alternatives do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more alternatives or that one or more alternatives necessarily include logic for deciding, with or without other input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular alternative. The terms “comprising,” “including,” “having,” and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list.
[0053] Disjunctive language such as the phrase “at least one of X, Y, Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to present that an item, term, etc., may be either X, Y, or Z, or any combination thereof (e.g., X, Y, and/or Z). Thus, such disjunctive language is not generally intended to, and should not, imply that certain alternatives require at least one of X, at least one of Y, or at least one of Z to each be present.
[0054] While the detailed description has shown, described, and pointed out novel features as applied to various alternatives, it can be understood that various omissions, substitutions, and changes in the form and details of the devices or algorithms illustrated can be made without departing from the scope of the disclosure. As can be recognized, certain alternatives described herein can be embodied within a form that does not provide all of the features and benefits set forth herein, as some features can be used or practiced separately from others.

We Claim:

1.A method of joining two cylindrical bodies, the method comprising:
aligning a first cylindrical body and a second cylindrical body along a longitudinal axis passing through centres of the first cylindrical body and the second cylindrical body, wherein the first cylindrical body and the second cylindrical body have a protruded central cylindrical region surrounded by one or more concentric base regions, wherein the first cylindrical body and the second cylindrical body are aligned such that the protruded central cylindrical region of the first cylindrical body and the protruded central cylindrical region of the second cylindrical body are separated by a first predefined distance;
fusing the protruded central cylindrical region of the first cylindrical body and the protruded central cylindrical region of the second cylindrical body; and
fusing the one or more concentric base regions of the first cylindrical body and the one or more concentric base regions of the second cylindrical body to achieve a fused preform.
2. The method as claimed in claim 1, wherein the first cylindrical body and the second cylindrical body are glass preforms for manufacturing optical fiber, wherein the protruded central cylindrical region is a core region of an optical fiber drawn from the fused preform, one or more concentric base regions is a cladding of the optical fiber drawn from the fused preform.
3. The method as claimed in claim 1 further comprising melting the protruded central cylindrical region of the first cylindrical body and the protruded central cylindrical region of the second cylindrical body, prior to fusing the protruded central cylindrical region of the first cylindrical body and the protruded central cylindrical region of the second cylindrical body.
4. The method as claimed in claim 1 further comprising simultaneously heating and rotating the first cylindrical body and the second cylindrical body, prior to melting the protruded central cylindrical region of the first cylindrical body and the protruded central cylindrical region of the second cylindrical body such that a relative rotational motion between the first cylindrical body and the second cylindrical body is zero.
5. The method as claimed in claim 1 further comprising reducing the first predefined distance between the protruded central cylindrical region of the first cylindrical body and the protruded central cylindrical region of the second cylindrical body to a second predefined distance prior to fusing the protruded central cylindrical region of the first cylindrical body and the protruded central cylindrical region of the second cylindrical body.
6. The method as claimed in claim 1, wherein the protruded central cylindrical region of the first cylindrical body and the protruded central cylindrical region of the second cylindrical body are silica doped with germanium, thereby causing the protruded central cylindrical region of the first cylindrical body and the protruded central cylindrical region of the second cylindrical body to start melting before the one or more concentric base regions.
7. A preform joining apparatus (600) for two cylindrical bodies (500), the preform joining apparatus (600) comprising:
a gripping mechanism (602) for holding a first cylindrical body and a second cylindrical body such that the first cylindrical body and the second cylindrical body are aligned at a longitudinal axis passing through centres of the first cylindrical body and the second cylindrical body, wherein the first cylindrical body and the second cylindrical body have a protruded central cylindrical region surrounded by one or more concentric base regions, wherein the protruded central cylindrical region of the first cylindrical body and the protruded central cylindrical region of the second cylindrical body are separated by a first predefined distance;
a glass burner (100) for melting the protruded central cylindrical regions and the one or more concentric base regions of the first cylindrical body and the second cylindrical body; and
a sliding mechanism (604) for reducing distance between the protruded central cylindrical regions such that the protruded central cylindrical region of the first cylindrical body and the protruded central cylindrical region of the second cylindrical body are fused followed by the one or more concentric base regions, thereby achieve a fused preform.
8. The preform joining apparatus (600) as claimed in claim 7, wherein the glass burner (100) for preform joining, comprising:
a plurality of capillary tubes (106) in a funnel-like outer tube (104), a flammable gas injector (109) and a supporting gas injector (107) so as to melt protruded central cylindrical regions and one or more concentric base regions of a first cylindrical body and a second cylindrical body, wherein number of capillary tubes is selected such that the glass burner produces high heating power laminar flow flame structure with an increased flow of gases in a predetermined ratio for providing sufficient mixing of oxyhydrogen gas.
9. The preform joining apparatus (600) as claimed in claim 7, wherein an inlet for a supporting gas is situated at bottom of the glass burner (100) and thus has a bottom entry, where the supporting gas is oxygen gas that passes through the plurality of capillary tubes (106).
10. The preform joining apparatus (600) as claimed in claim 7, wherein an inlet for a flammable gas is situated at outer side of the glass burner (100) and thus has a side entry, where the flammable gas is hydrogen gas that passes through the funnel-like outer tube (104) and between the plurality of capillary tubes (106).
11. The preform joining apparatus (600) as claimed in claim 7, wherein the first cylindrical body and the second cylindrical body are glass preforms for manufacturing optical fiber, the protruded central cylindrical region is a core region of an optical fiber drawn from the fused preform, one or more concentric base regions is a cladding of the optical fiber drawn from the fused preform.
12. The preform joining apparatus (600) as claimed in claim 7 further comprising a rotating mechanism (606) that rotates the gripping mechanism (602), causing simultaneous heating and rotating the first cylindrical body and the second cylindrical body, such that a relative rotational motion between the first cylindrical body and the second cylindrical body is zero.
13. The preform joining apparatus (600) as claimed in claim 7, wherein the protruded central cylindrical region of the first cylindrical body and the protruded central cylindrical region of the second cylindrical body are silica doped with germanium, thereby causing the protruded central cylindrical region of the first cylindrical body and the protruded central cylindrical region of the second cylindrical body to start melting before the one or more concentric base regions.