JP5114409B2 - Welding method for joining components made of high silica material and apparatus for carrying out the method - Google Patents

Description

  The present invention is a welding method for joining a first constituent material and a second constituent material made of at least one high silica material by forming an integral joint between the joint surfaces of these constituent materials, and a rotational movement means The step of clamping the component material to the substrate, the step of moving the component material by means of rotational movement in the direction of the central axis, and the region of the joint surface between the first component material and the second component material simultaneously by means of at least one heating burner The present invention relates to a welding method including a step of forming a component assembly having a welded seam by heating and softening, and pressing joint surfaces to each other, and a step of cooling the component assembly.

  Furthermore, the present invention is an apparatus for welding and joining a first constituent material and at least one second constituent material made of a high silica material, the rotational movement means for clamping the constituent material and moving it in the direction of the central axis, and the constituent material The present invention relates to an apparatus including at least one heating burner for heating and softening a region of the mutual bonding surface.

Here, a high silica material is a doped or undoped quartz glass having a SiO ₂ content of at least 85%. This material is hereinafter simply referred to as “quartz glass”. Quartz glass has a low coefficient of thermal expansion, is optically transparent over a wide range of wavelengths, and has high chemical and thermal resistance.

  Quartz glass components have many uses, for example, semi-finished products in the form of hollow or solid cylinders when manufacturing optical fibers, sleeves, tubes, bulbs, cover plates or lamp reflector supports for lamp manufacturing, UV In the infrared and visible spectral range emitters, chemical equipment components or semiconductor manufacturing, quartz glass reactors and equipment for processing semiconductor elements, jigs, bell jars, crucibles, protective shields or simple quartz glass components, For example, a tube, rod, plate, flange, ring or block. For special characteristics, quartz glass is doped with other materials such as titanium, aluminum, boron, and germanium.

  It is often required to bond individual quartz glass components together. For example, a quartz glass body having a complicated shape is formed, bonded to a quartz glass component to have a special function, and there are other attachments and shaping. As a reference example, there is a quartz glass cylinder component assembly used when making optical fibers and optical preforms in a stretching process. In this stretching process, it is particularly important that a stretching valve is formed at the end of the semi-finished product during the tensioning stage, from which the component is stretched to a predetermined shape and size. become. It takes some time to form the drawing valve, which sacrifices the production capacity of the drawing furnace, and because the drawing furnace is very thermally stressed during the pulling stage, the service life of the drawing furnace Will be sacrificed. As the outer diameter of the semi-finished product increases, the time spent in the pulling stage also increases.

  If a profile similar to a stretch valve is first created at the lower end of the semi-finished product, the non-productive pulling step can be considerably shortened. Therefore, what is proposed in Japanese Patent Laid-Open No. 10-182179 (1998) is to weld a mounting piece in the form of a dummy tube having a small diameter to the lower end of a quartz glass cylinder to be stretched. This shortens the pulling process and at the same time reduces material loss.

  In general, a component of quartz glass that serves as a holder is also welded to the upper end of a quartz glass cylinder that is to be stretched. A suitable method for making such an assembly is described in EP1042241A1. It has been proposed to butt weld a quartz glass tube, which is an optical fiber preform, to a dummy tube by chamfering the front surfaces to be joined to each other before forming the welded joint, and then a propane / oxygen burner. Welding the joining surfaces by means of and then pressing the joining surfaces together. As an alternative to a propane / oxygen burner, an electric furnace that softens the joint surface can also be used.

  The welding process consists of clamping both quartz glass components with lathe means, moving the quartz glass components towards each other, butting the surfaces of the quartz glass components together, heating, softening and softening Forming a component assembly having weld seams by pressing the surfaces together and cooling the component assembly to ambient temperature.

  If necessary, press the graphite template against the softened outer surface and shape the surface during this process.

  When the quartz glass component is welded, impurities may be formed or released from the surrounding environment, a heating burner, or a boundary wall. These particles are deposited on the quartz glass component to be joined, especially on the softened joint surface, but these particles are harmful impurities and can cause bubbles and other substances at the interface during further processing of the assembly. May cause damage or even destruction.

  Furthermore, during welding, undesirable plastic deformation tends to occur in the melting zone. The deformation can be eliminated by troublesome mechanical work, but it is normal for the dimensions to be distorted. Such deformation is facilitated by irregular and uncertain heating conditions during the welding process.

  It is an object of the present invention to provide a method of creating a tight weld seam in an accurate and reproducible manner between the quartz glass components to be joined, greatly avoiding impurities.

  Another object of the present invention is to provide a simple, reliable and inexpensive device for creating a weld seam between quartz glass components, which device implements the method of the present invention. Especially suitable for.

  With regard to the method, this object is achieved according to the invention starting from the welding method described above, in which the component is heated and softened in the region of the interconnection surface within the surrounding enclosure. The enclosure includes openings opposite to each other in the central axis, through which the components to be welded enter, and the enclosure is provided with a free surface in the form of an inner layer of high purity quartz glass With quartz glass walls.

  In accordance with the present invention, one or several heating burners are used to heat and soften the component in the area of the joint surface. Compared to using an electric furnace for this purpose, the use of a heated burner provides a better energy balance in the system and requires less capital investment.

  In contrast to the prior art, the component is heated and softened by means of a heating burner inside the enclosure. The enclosure acts as thermal insulation and at the same time acts as a heat storage tank. This has the advantage of being constant over time, producing a locally uniform heating profile and improving the quality of the weld seam and facilitating reproducibility. The enclosure reduces the heat loss of the heating burner and facilitates slow cooling of the components being welded together, minimizing thermal stresses that lead to cracks and breaks in the weld seam.

  In addition, the enclosure substantially shields the interior from the external environment and greatly eliminates stray particles and other impurities from the heating zone.

  The enclosure substantially surrounds only the areas where the components are softened and welded together. On both sides thereof, two openings are provided opposite to each other with a central axis, and a component to be welded through the openings is introduced into the interior. Further, a flushing gas for discharging impurities is passed through the inside.

  The enclosure has a quartz glass wall. Quartz glass is a special material for the component material to be welded.

  Furthermore, the wall is provided with a free surface in the form of an inner layer of high purity quartz glass. The walls themselves may be made of cheap quartz glass of moderate quality. The inner layer of high purity quartz glass prevents or reduces impurities out of the walls and into the heated area.

  Here, high purity quartz glass refers to quartz glass having a total content of oxides of Li, Na, K, Mg, Ca, Fe, Cu, Ni, Cr and Mn of 10 ppm by weight or less.

  High-purity quartz glass can be synthesized by high-temperature chlorination of quartz glass or natural quartz glass in a chlorine-containing atmosphere.

  In a particularly preferred variant of the method, the interior has a round cross section as viewed in the direction of the central axis.

The fact that the interior has a round cross section facilitates the creation of a concentric heating profile on the central axis, thereby heating the component with a circular cross section uniformly. In addition, this facilitates the adjustment of the generally laminar flushing gas flow in the direction of the central axis and eliminates dead corners where impurities and particles accumulate over time.
It has been found particularly useful that the walls of the enclosure are made of opaque quartz glass melted from natural materials.

  The opacity of quartz glass improves the thermal insulation effect of the enclosure and facilitates the setting of a uniform temperature profile that is constant over time in the heating zone. The use of natural quartz glass over synthetic glass is preferred because of cost. Opaque quartz glass tubes are particularly suitable for this purpose, and the trade name “Rotosil” from Heraeus Quartz Glass, Hanau is available at a low price. In general, when making an opaque tube of quartz glass, a transparent and dense surface layer is formed on the surface closest to the heating element during solidification (vitrification). The maximum thickness of this surface layer is 3 mm, and the surface layer does not impair the thermal insulation effect of the opaque walls that are not.

  For cost reasons, the high purity quartz glass of the inner layer is preferably obtained by high temperature chlorination of a natural material in a chlorine containing atmosphere.

High-purity quartz glass consists of opaque quartz glass with a density of 2.15 g / cm ³ to 2.18 g / cm ³ and is made from a material obtained by wet grinding of amorphous SiO ₂ particles. It turned out to be preferable. Such quartz glass is commercially available, for example, under the trade name “OM100” from Heraeus Quartz Glass, Hanau. Quartz glass, does not exceed 500μm particle size, baked preferably be sintered from SiO ₂ particles in the range not exceeding 100 [mu] m, the range of SiO ₂ particles having a particle size between 1μm and 100 [mu] m in consideration of the maximum volume portion Conclude. Coarse amorphous particles are made into particles by a slip method by wet milling. In that case, due to the interaction, the SiO ₂ particles are already interacting with a high density of aqueous slip, which improves the stability of the slip and increases the density of the resulting opaque quartz glass.

  It has been found that the thickness of the inner layer should be in the range of 10 mm to 12 mm.

  The thicker the inner layer, the more effectively it will prevent contamination of the components to be joined. On the other hand, high purity raw materials are used to make the inner layer, making it more expensive. The above thickness range seeks an appropriate compromise in consideration of these requirements.

  The heating burner may be placed inside the enclosure. However, in a preferred variant of the method, the at least one heating burner is forced into the interior from the lateral opening of the enclosure.

  Accordingly, the heating burner is disposed substantially outside the enclosure. The thermal insulation wall of the enclosure shields the heating burner and shields the media supply line from the heat in the heating zone. As a result, the heated burner does not interfere with the flushing gas flow through the enclosure.

  It has been found that it is better to supply purified air to the heating burner.

  This ensures that the at least one heating burner inhales pure air and substantially avoids contamination, such as by particles of the component being joined.

  Advantageously, the enclosure is a multi-part structure.

  The multi-part structure makes it easy to install the enclosure. Furthermore, this makes maintenance easy and inexpensive. This is because only the worn portion of the enclosure needs to be replaced.

  Furthermore, it has been found that the component assembly may be cooled in the enclosure.

  The enclosure ensures a relatively slow cooling of the component assembly heated to the processing temperature. In this respect, the enclosure functions as an annealing furnace.

  It is preferable to heat and soften the constituent material at a processing temperature of 2200 ° C. or higher, and to take at least 5 minutes for cooling from the processing temperature to 1000 ° C.

  Thermal stress is minimized by cooling the component assembly relatively slowly from the processing temperature.

  In one embodiment of an enclosure having a circular cross section, the components to be welded together are cylindrical and the ratio between the largest outer diameter of the cylinder and the inner inner diameter is 1.5 and 3 And preferably in the range between 2 and 2.5.

  During this process, the annular gap between the enclosure and the component outer surface is adequate for heat transfer and the flow of flushing gas that may occur.

  With regard to the device, the above object starts from a device of the type described above and surrounds according to the invention to enclose the interior and to heat and soften the component in the region of the interconnecting surface of the component. The enclosure has openings (a plurality) opposite to each other in the direction of the central axis, through which the components to be welded enter into the enclosure; and The enclosure comprises a quartz glass wall which has a free surface in the form of an inner layer of high purity quartz glass.

  Within the heating zone created with the aid of one or several heating burners, the components are heated at their joint surfaces and softened. In contrast to the prior art, the heating zone is created inside the enclosure. This enclosure serves the purpose of thermal insulation and at the same time serves as a heat storage tank. This creates a locally uniform heating profile that remains constant over time, improving the quality of the weld seam and facilitating reproducible manufacturing. The enclosure reduces the heat loss of the heating burner, and additionally facilitates slow cooling of the components welded together, minimizing cracks and breaks in the weld seam.

  Because the enclosure shields the interior from the external atmosphere, stray particles and other impurities are substantially not in the heating zone.

  The interior substantially surrounds only the heating zone where the components to be joined are heated and welded.

  The enclosure has an opening facing in the direction of the central axis, through which the component to be welded extends. In addition, a flushing gas that eliminates impurities is passed through the enclosure, i.e. through the opening.

  Useful developments of the device according to the invention will become apparent from the dependent claims. The structure of the device as defined in the dependent claims follows the dependent claims of the method of the present invention, and reference is made to the above description of the relevant method claim for a supplementary explanation.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  The apparatus of FIGS. 1 and 2 welds a holder in the form of a quartz glass tube 1 to a hollow cylinder 2 on its front side. The assembly of the quartz glass tube 1 and the hollow cylinder 2 to be made is stretched into an optical fiber combined with a so-called core rod inserted into the preform of the optical fiber or into the inner hole of the hollow cylinder 2.

  The quartz glass tube 1 is made of, for example, low-quality quartz glass containing a large amount of impurities, bubbles and the like. Even though the inner diameter is the same, the thickness of the quartz glass tube 1 is slightly thinner than the quartz glass cylinder 2. During the stretching process, the hollow cylinder 2 is held in a drawing furnace by a quartz glass tube 1 and / or the quartz glass tube 1 serves as a tension during stretching. For this reason, such a quartz glass tube is provided at one end or both ends of the hollow cylinder 2 made of quartz glass.

Furthermore, this device comprises a lathe in the form of a chuck 3 which is a rotational movement means, clamps the quartz glass tube 1 at one end thereof, makes the central axes 4 concentric with each other and the front surfaces to be welded to each other. The hollow cylinder 2 is clamped at the other end of the lathe so as to face each other. The opposing area of the quartz glass tube 1 and the hollow cylinder 2 is heated and softened inside a muffle tube 5 which is an opaque quartz glass enclosure having an inner diameter “D” of 400 mm. The muffle tube 5 is formed as a three-part member and it is open on both sides. In the center portion, two heating burners 7 and 8 enter the inside 9 through an opening 6 provided in the lateral wall.

The muffle tube 5 is made of a quartz glass tubular substrate 10, which is made by melting natural quartz, and is marketed under the trade name “Rotosil”. The muffle tube 5 is provided with a longitudinal slit over its entire length, which acts as an expansion joint. The inner surface of the substrate 10 facing the interior 9 is made by dissolving high-quality quartz particles and is lined with an inner layer 11 having a thickness of 10 mm to 12 mm. This is a natural quartz particle that is already commercially available under the trade name “IOTA Standard” (distributor: Unimin Corp, USA). The already cleaned quartz particles are further cleaned in a chlorine-containing atmosphere at a higher temperature (900 ° C.) and then used to dissolve to form an inner layer. Table 1 shows typical impurities of the IOTA standard before and after high temperature chlorination.

  The concentration shown in Table 1 is weight ppb. Impurity content was measured by ICE-0ES.

Alternatively, a material for making a high purity opaque quartz glass muffle tube 5 is commercially available under the trade name “OM 100” with Hanau Heraeus Quartz Glass. Coarse amorphous particles are sintered from SiO _{2 having} an average particle size of about 60 μm made by a slip method by wet milling into opaque quartz glass. This quartz glass is identified by its high purity and density of about 2.16 g / cm ³ .

  On the side facing the heating burners 7 and 8, the inside of the muffle tube 5 is covered with a simple shell-like insertion portion 13 of high-purity quartz glass, which is a relatively complicated central portion due to the structure of the muffle tube 5. Is protected from the action of heat, and in addition, the heat capacity of all the components is increased, and the temperature distribution inside the muffle tube 5 is made uniform.

  A high purity graphite holder (not shown) positions and holds the muffle tube 5 correctly.

  A suction device 12 is provided above the muffle tube 5. This suction device opens in front of the muffle tube 5 and extends partially to suck in hot exhaust gas.

  In addition, an ultra-pure air supply device (not shown in FIG. 1) is provided around the burner mouth of the heating burners 7, 8 to ensure that the two heating burners 7, 8 inhale only pure air. Thus, contamination of the constituent materials 1 and 2 to be joined is largely avoided. The heating burners 7, 8 are made of quartz glass.

  This embodiment of the device using the muffle tube 5 according to the invention reduces the amount of impurities released into the environment as compared to individual modules of refractory materials, specifically enclosures made from quartz glass blocks. Yes.

  An embodiment of the method of the present invention will be described in detail with reference to FIGS.

High purity silicon tetrachloride is evaporated and a quartz glass material is made by the known OVD method by flame hydrolysis in an oxyhydrogen gas flame. During this process, SiO ₂ particles are deposited on a rotating quartz glass rod to create a large volume of porous soot material, which is then vitrified at 1600 ° C. to form a quartz glass material. Both ends of this quartz glass material are cut off, and the outer peripheral surface is polished with a cylinder polishing machine. A hollow cylinder of quartz glass is made by drilling a hole in the quartz glass material by using a core drill. The resulting quartz glass hollow cylinder has an outer diameter of 180 mm and an inner diameter of 50 mm and is etched with hydrofluoric acid, washed with pure water and dried.

  In order to join the high purity hollow cylinder 2 to the quartz glass tube 1 of low purity quartz glass, the hollow cylinder 2 and the quartz glass tube 1 are clamped to the lathe chuck 3 along the concentric axis 4 to drive the lathe. By means of movement towards each other, these are made to oppose inside the muffle tube 5 in the operating area of the heating burners 7, 8. The area facing the weld is heated with a heating burner 7, 8 to a temperature of about 2200 ° C. to 2300 ° C. for 20 minutes, softened in this process, and the front of the hollow cylinder 2 and the quartz glass tube 1 are pressed against each other simultaneously. Here, oxygen is passed through the holes of the hollow cylinder 2 and the quartz glass tube 1.

  The muffle tube 5 ensures a homogeneous temperature distribution during the welding process. After the welding is completed, the component assembly (2, 1) made as described above is placed in the muffle 5 for about 10 minutes and slowly cooled to a temperature of 1000 ° C. or lower during this process.

  According to the static tensile strength measurement, no fracture occurred in the weld zone even when a maximum test load of 3 tons was applied.

  In another way, which is particularly advantageous for welding large components, the heating burners 7, 8 are not arranged in parallel to each other but are distributed around the wall of the muffle tube 5 in the interconnect surface area. In this way, the heating action of the heating burners 7 and 8 is distributed over a large area of the muffle tube 5, and as a result, the heat load applied thereto is reduced. The heating burners 7 and 8 may be arranged to face each other on the wall of the muffle tube, for example.

1 shows an embodiment of the device of the invention with a muffle tube-shaped enclosure on the jacket surface. It is a front view of the muffle tube of FIG.

Claims (20)

  A welding method for joining at least one second constituent material composed of a first constituent material and a high silica material by forming an integral joint between the joining surfaces of these constituent materials (1, 2), and rotational movement A step of clamping the component (1, 2) to the means, a step of moving the component (1, 2) toward each other by means of rotational movement in the direction of the central axis (4), at least one heating burner ( 7 and 8) in the welding method including the steps of simultaneously heating and softening the areas of the joint surfaces to each other, pressing the joint surfaces together to form a component assembly including a weld seam, and cooling the component assembly The component (1, 2) is heated and softened in the region of the interconnection surface within the enclosure surrounding the interior (9), the enclosure comprising openings facing each other in the central axis, The components to be welded into the interior through these openings, and the enclosure comprises a quartz glass wall with an inner layer (11) of high purity quartz glass, the inner surface of the inner layer forming a free surface Welding method characterized by being made.   The method according to claim 1, wherein the quartz glass wall of the enclosure comprises a tubular substrate (10), and the inner layer lines the inner surface of the tubular substrate.   3. A method according to claim 2, wherein the tubular substrate of the enclosure (5) comprises opaque quartz glass melted from natural materials.   4. A method according to claim 1, wherein the interior (9) has a round cross section as viewed in the direction of the central axis (4).   The method according to any one of claims 1 to 4, wherein the high-purity quartz glass is obtained from a natural material subjected to high-temperature chlorination in a chlorine-containing atmosphere. High purity quartz glass consists of opaque quartz glass with a density of 2.15 g / cm ³ to 2.18 g / cm ³ and is made from a material obtained by wet grinding of amorphous SiO ₂ particles. The method according to claim 1.   The method according to any one of claims 1 to 6, wherein the thickness of the inner layer (11) is in the range of 10 mm to 12 mm.   7. The method as claimed in claim 1, wherein at least one heating burner (7, 8) projects into the interior (9) from the lateral opening (6) of the enclosure. The method according to claim 1 , wherein purified air is supplied to the heating burner.   10. A method according to any preceding claim, wherein the component assembly is cooled within the enclosure.   11. The method according to claim 10, wherein the component (1,2) is heated and softened at a treatment temperature of 2200 [deg.] C. or higher, and cooling from the treatment temperature to 1000 [deg.] C. takes at least 5 minutes.   The components (1, 2) to be welded together are cylindrical and the ratio between the maximum diameter of the cylinder and the inner diameter of the interior (9) is in the range between 1.5 and 3 Item 12. The method according to any one of Items 1 to 11.   Rotating and moving means for welding and joining at least one second component made of a first component and a high silica material, wherein the component (1, 2) is clamped and moved in the direction of the central axis (4) And at least one heating burner (7, 8) that heats and softens the region of the joint surfaces of the constituent members (1, 2), surrounds the interior (9), and the constituent members An enclosure for heating and softening the component in the region of the (1,2) mutual joining surface, the enclosure comprising openings facing each other at the central axis into which the component to be welded enters; and The enclosure comprises a quartz glass wall with an inner layer (11) of high purity quartz glass, the inner surface of the inner layer forming a free surface.   14. A device according to claim 13, wherein the quartz glass wall of the enclosure comprises a tubular substrate (10), the inner layer lining the inner surface of the tubular substrate.   15. A device according to claim 14, wherein the tubular body of the enclosure (5) is made of opaque quartz glass melted from natural materials.   16. Device according to claim 13, wherein the interior (9) has a round cross section as viewed in the direction of the central axis (4).   The device according to any of claims 13 to 16, wherein the thickness of the inner layer (11) is in the range of 10 mm to 12 mm.   Device according to any of claims 13 to 17, wherein at least one heating burner (7, 8) projects into the interior (9) from a lateral opening (6) of the enclosure.   19. The device according to claim 13, wherein the purified air is supplied to at least one heating burner (7, 8).   The components (1, 2) to be welded together are cylindrical, and the ratio between the maximum diameter of the cylinder and the inner diameter of the interior (9) is in the range of 1.5 and 3. The apparatus in any one of 13-19.

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