Inlay, sleeve shaft with inlay and refractory tube with sleeve shaft

Abstract

The invention relates to an inlay for a sleeve shaft, to a sleeve shaft having such an inlay and to a refractory tube into which such a sleeve shaft is inserted.

Description

TECHNICAL FIELD

[0001] The invention relates to an inlay for a bushing shaft, a bushing shaft having such an inlay and a refractory tube into which such a bushing shaft is inserted. BACKGROUND

[0002] In the prior art, during a mechanical glass tube drawing process, such as the Danner process, a fluid flows in a controlled manner through a carrier which carries a refractory tube. The refractory tube in turn provides a surface area over which the molten glass flows, which is then shaped into a glass tube bundle in a shaping zone arranged at one end of the refractory tube.

[0003] Based on the selected fluid parameters, such as volume flow rate and pressure, the speed at which the glass tube bundle is drawn from the refractory tube and the temperature conditions in the shaping zone, the geometric parameters of the glass tube bundle produced can be influenced.

[0004] The fluid, which can be a gaseous medium, such as air, flows through the carrier to the shaping zone. The carrier can be in the form of a bushing shaft, which is, for example, a hollow shaft made of steel. Typically, the refractory tube has a temperature of, for example, 1100 to 1200°C, which, as the carrier is arranged within the refractory tube, in turn heats the carrier.

[0005] Due to the high temperatures at the bushing shaft, the steel material of the bushing shaft undergoes a cinder-corrosion process in the presence of oxygen. This results in the presence of particles in the form of cinder particles originating from the bushing shaft material in the inner cavity enclosed by the bushing shaft. Although the fluid flowing through the carrier is typically not sufficient to rotate the particles within the inner cavity, the particles are transported along the inner surface of the bushing shaft to the shaping zone mediated by the flowing fluid, gravity (as the refractory tube, and thus the carrier, can be inclined) and the rotational movement of the bushing shaft.

[0006] In the shaping zone, the particles can then come into contact with the inner surface of the glass material of the glass tube bundle and contaminate it while it is a viscous fluid. After the glass material has hardened after contacting the particles, the particles are permanently confined on the inner surface of the glass tube bundle.

[0007] As the particles cannot be removed from the glass tube bundle in subsequent process steps, the contaminated product is rejected by the inspection system of the production process, thereby reducing the production yield.

[0008] Conventionally, it has been proposed to cover the inner surface of the bushing shaft with a noble metal, ceramic or other corrosion-resistant protective coating of suitable temperature resistance to prevent the occurrence of cinder particles in the inner cavity enclosed by the bushing shaft. Other attempts involve the use of inert gases as the fluid or even the use of a completely metal-free, in particular iron-free, bushing shaft, for example made of ceramic or even glass.

[0009] However, the results are not satisfactory or the measures are complex, costly or difficult to implement.

[0010] In addition, further processing of the inner surface of the sleeve shaft, for example sandblasting of the inner surface, in order to minimize the corrosion process, does not significantly reduce the particles either.

[0011] Furthermore, it was proposed to position a fluid filter in the end portion of the sleeve shaft and to direct the entire fluid through such a filter. However, it turned out that such a filter interferes with the fluid flow dynamics, which in turn adversely affects the geometry and quality of the glass tube bundle. In addition, such a filter is prone to clogging, requiring regular maintenance of the system and replacement of the filter. However, this leads to long downtimes in production, thus leading to increased costs.

[0012] It is therefore an object of the present invention to overcome the above-mentioned disadvantages with respect to the prior art by providing a means which allows to reduce the contamination of the glass tube bundle by particles or even to completely prevent such contamination in a simple and cost-effective manner. It is a further object of the present invention to provide a sleeve shaft and a refractory tube which overcome the known disadvantages. SUMMARY

[0013] This problem is solved by the first aspect according to the present invention, wherein an inlay for a sleeve shaft for at least partially collecting particles originating from the sleeve shaft material is proposed, wherein at least one fluid can flow through the sleeve shaft in an axial direction parallel to the main extension of the sleeve shaft,

[0014] wherein the inlay comprises at least one first wall portion, and wherein the inlay is at least partially or can be at least partially inserted into the sleeve shaft such that at least one portion of the first wall portion has a radial distance to at least one first region of the inner surface of the sleeve shaft, and thus, the inlay together with the first region of the inner surface of the sleeve shaft encloses at least one volume domain which is limited in the axial direction by the limiting element comprised by the inlay.

[0015] The present invention is therefore based on the surprising finding that due to the nature of the particles and given general conditions, the particles usually move tightly along the inner surface of the sleeve shaft rather than being distributed in the entire inner cavity enclosed by the sleeve shaft. These particles can thus be prevented from coming into contact with the glass material and thus from contaminating the glass material. By providing a volume domain within the sleeve shaft, the respective moving particles, for example soot particles originating from the sleeve shaft material, can be collected here, preventing the particles from moving to the forming area.

[0016] By using the proposed inlay, the volume domain can be provided in a very straightforward and cost-effective manner. The inlay itself can be designed to be inserted quickly and easily into the sleeve shaft of the refractory tube. This makes it easy to retrofit almost any existing refractory tube with the inlay according to the present invention in an efficient and inexpensive manner. In particular, neither the entire sleeve shaft has to be replaced nor has any coating to be applied at a location within the sleeve shaft which is usually difficult to access. Both are very complex and require the removal of the sleeve shaft from the refractory tube by subsequent external treatment. Thus, by the present invention, the downtime of the production process can be reduced to a minimum.

[0017] Since the inlay is much smaller than the sleeve shaft, a material for the inlay or a corrosion- resistant coating for the inner surface within the inlay can be used which was not used with the sleeve shaft before due to the high costs.

[0018] For example, the inlay can contain 5-15 wt.%, preferably 8-11 wt.% of Fe.

[0019] In a preferred embodiment, the axial length of the inlay is between 100 and 350 mm, preferably between 150 and 250 mm, more preferably between 180 and 220 mm, and most preferably 200 mm.

[0020] Another advantage of the inlay is that it can be designed such that it provides a volume large enough to trap particles so that the inlay can remain within the sleeve shaft during the production process for several years without the need to remove the collected particles from the volume domain.

[0021] In various tests performed by the inventors and as confirmed in production by monitoring the glass tube bundle, it has been proven that the inlay neither affects the fluid flow within the sleeve shaft or in the forming zone nor the quality or the geometric properties of the glass tube line.

[0022] The volume domain is limited in the radial direction by the first wall portion and the first region of the inner surface of the sleeve shaft and in the axial direction by the limiting element.

[0023] Thus, the present invention provides a cheap and powerful solution to prevent the glass tube bundle from being contaminated with particles, such as soot particles originating from the sleeve shaft material.

[0024] In an embodiment, it is alternatively or additionally preferred that particles which are moved along the inner surface of the sleeve shaft in the first axial direction at least partially mediated by the fluid flow and / or the gravitational force reach the volume domain and are trapped and prevented from further movement in the axial direction.

[0025] In an embodiment, it is alternatively or additionally preferred that the inlay comprises at least one region in the form of a cylinder, and that the first shell of at least one first portion of the cylindrical region comprises a first wall portion, wherein preferably the first portion comprises at least one first end portion of the inlay.

[0026] If the inlay comprises a region in the form of a cylinder, it can be particularly easily inserted into the sleeve shaft, which usually provides a cylindrical form of the enclosed volume, i.e. the inner cavity. For example, the inlay can then be arranged concentrically within the sleeve shaft in an easy manner. At the same time, the first shell of the region (of the first portion) can provide a first wall portion, which leads to a compact design.

[0027] If the first portion is an end portion of the inlay, a large volume domain can be provided inside the sleeve shaft.

[0028] In an embodiment, it is alternatively or additionally preferred that the second shell of at least one second portion of the cylindrical region, different from the first portion of the cylindrical region, comprises at least one second wall portion, wherein a first outer diameter of the first wall portion is smaller than a second outer diameter of the second wall portion, wherein preferably the second portion comprises at least one second end portion of the inlay, and / or wherein the second portion follows the first portion in the axial direction, in particular the second end portion of the inlay at the end opposite to the first end portion of the inlay.

[0029] If the second shell of the second portion of the cylindrical region provides a second wall portion, the inlay can adapt to the interior geometry of the sleeve shaft.

[0030] In an embodiment, it is alternatively or additionally preferred that the limiting element is formed and / or arranged in at least one end portion of the first wall portion, preferably the limiting element is integral with the first wall portion and / or an end portion of the first wall portion facing away from the first end portion of the inlay.

[0031] Arranging the limiting element at the end portion of the first wall portion allows to define a determined volume domain.

[0032] In an embodiment, it is alternatively or additionally preferred that the limiting element is formed by at least one transition from the first wall portion to the second wall portion, wherein preferably the transition is designed in the form of at least one step and / or in the form of at least one arcuate segment in at least one cross section.

[0033] If the transition between the first and the second wall portion serves as limiting element, a compact design and the implementation of an inherently thus efficient limiting element are possible.

[0034] In an embodiment, it is alternatively or additionally preferred that the insert comprises at least one fixing device for arranging the insert at the sleeve shaft, at least one distant element and / or at least one stop element, preferably the stop element is designed in the form of at least one collar, is designed at least partially integral with the limiting element, is designed at least partially integral with the second wall portion and / or is arranged in at least one end portion of the insert, in particular at the end portion of the insert opposite the first wall portion.

[0035] The provision of one or more fixing devices allows the insert to be safely fixed at the sleeve shaft. This increases safety. The stop element allows the insert to be comfortably and safely mounted within the sleeve shaft, since the stop element effectively prevents the insert from being inserted too deeply into the sleeve shaft.

[0036] The distant element allows the insert to be held within the sleeve shaft in a safe and / or concentric manner.

[0037] In an embodiment, it is alternatively or additionally preferred that the insert is connected or can be connected to the sleeve shaft in a form- and / or friction-locked manner by welding, and / or the volume region is at least partially in the form of at least one annular volume.

[0038] If the insert is adapted to be connected (or even connected) to the sleeve shaft in a form- and / or friction-locked manner by welding, a secure connection can be provided between the insert and the sleeve shaft.

[0039] In a preferred embodiment, the insert can comprise a fixing device. The fixing device allows the insert to be arranged firmly at the sleeve shaft. In particular, some fixing elements allow reversible release of the insert. This allows particles to be removed from the volume region very easily.

[0040] Here, form locking refers to a connection that arises through interlocking of at least two connection members. As a result, the connection members cannot be loosened even if the force transmission is interrupted or does not exist at all. In other words, in a form-locked connection, one connection member blocks the other connection member. Under operational load, a compression force acts in the normal direction, i.e. perpendicular to the surface of the connection members. This "blocking" occurs in at least one direction. If a second pair of homogeneous surfaces is arranged opposite, the opposite direction is also blocked. If this pair consists of two coaxial cylindrical surfaces, there is a form lock in all directions perpendicular to the plane of the cylindrical axes.

[0041] Here, friction locking refers to a connection that requires a normal force on the surfaces to be connected. As long as the tangential force does not exceed the normal force caused by static friction, their mutual displacement can be avoided. If the tangential load force is greater than the static friction force, the normal force or friction connection is eliminated and the surfaces slide relative to each other.

[0042] A toroidal volume is particularly preferred, since it provides rotational symmetry of the system, so that a stable operation of the system is possible.

[0043] In an embodiment, it is alternatively or additionally preferred that the particles comprise oxidation products of the sleeve shaft material, ash particles and / or corrosion particles, which particles are preferably produced by a reaction of steel, in particular chrome-nickel steel, with oxygen at temperatures between 1000 and 1500 °C.

[0044] Here, it is preferred that the particles can alternatively or additionally also comprise particles contained in the fluid.

[0045] In an embodiment, it is alternatively or additionally preferred that the insert substantially does not negatively influence the fluid flow within the sleeve shaft and / or substantially does not influence the shape, quality or geometric properties of the produced glass tube bundle.

[0046] If the insert does not influence the fluid flow, the production process of the glass tube bundle is not adversely affected. Thus, the insert does not negatively influence the quality of the glass tube bundle.

[0047] This problem is solved by the second aspect according to the invention, wherein a sleeve shaft having at least one insert according to the first aspect of the invention for at least partially collecting particles originating from the sleeve shaft material is proposed, wherein at least one fluid can flow through the sleeve shaft in an axial direction parallel to the main extension of the sleeve shaft,

[0048] wherein the insert comprises at least one first wall portion, and

[0049] wherein the insert is at least partially inserted into the sleeve shaft such that at least one portion of the first wall portion has a radial distance to at least one first region of the inner surface of the sleeve shaft, and thus, the insert together with the first region of the inner surface of the sleeve shaft encloses at least one volume domain which is limited in the axial direction by limiting elements comprised by the insert,

[0050] wherein it is preferred that the sleeve shaft and the insert are arranged in a coaxial manner.

[0051] If the sleeve shaft is provided with a corresponding insert, the advantages of the insert as described above with respect to the first aspect of the invention can be applied without any further effort.

[0052] In an embodiment, it is alternatively or additionally preferred that the sleeve shaft comprises at least one steel, in particular chrome-nickel steel and / or 2.4633 steel, as a material.

[0053] It has been proven that the proposed materials provide a preferred sleeve shaft of good quality and stability, even under harsh environmental conditions, for example heat.

[0054] Preferably, in an embodiment, the sleeve shaft comprises a material comprising 24-26 wt.% Cr, 8-11 wt.% Fe, 2 wt.% Al and 55-66 wt.% Ni.

[0055] Preferably, in an embodiment, the sleeve shaft comprises a material comprising 30-35 wt.% Ni, 19-23 wt.% Cr and 39-41 wt.% Fe.

[0056] In an embodiment, it is alternatively or additionally preferred that the inlay is arranged at the sleeve shaft by means of at least one fixing device, in particular comprised by the inlay, and / or wherein the inlay is connected with the sleeve shaft in a welded manner, in a form-locked manner and / or in a friction-locked manner.

[0057] The fixing elements allow a firm arrangement of the inlay at the sleeve shaft. In particular, some fixing elements allow a reversible release of the inlay. This allows very easily removing the particles from the volume.

[0058] If a welded connection is chosen, a very reliable connection is provided.

[0059] Furthermore, with reference to the definitions provided above for the terms "form-locked" and "friction-locked", these are also applicable here.

[0060] In an embodiment, it is alternatively or additionally preferred that the inlay comprises at least one cylindrical region and at least one portion of the cylindrical region, in particular the housing of the second portion according to the first aspect of the application, comprises at least one second wall portion, wherein the second wall portion contacts at least one region of the inner surface of the sleeve.

[0061] This arrangement allows providing the volume in an efficient and easy manner. Furthermore, the contact region allows a more reliable connection between the inlay and the sleeve shaft, which increases the safety.

[0062] In an embodiment, it is alternatively or additionally preferred that the first region of the inner surface of the sleeve shaft is the inner surface of a first portion of the sleeve shaft, which has a larger inner diameter than another portion of the sleeve shaft, which follows the first portion of the sleeve shaft in a direction opposite to the axial direction.

[0063] It has been found that if a fluid flows through the sleeve shaft from a portion with a smaller inner diameter into a portion with a larger inner diameter, it is possible to deflect the fluid flow close to the inner surface of the sleeve shaft, i.e. into the shadow region of the volume enclosed by the sleeve shaft into the portion with the larger inner diameter. This is because a radial velocity seems to be generated by the transition from the smaller inner diameter to the larger inner diameter.

[0064] In this way, particles close to the inner surface of the sleeve shaft are guided closer to the trapping volume enclosed between the inlay and the sleeve shaft. Furthermore, it has been noticed that the absolute fluid velocity in this shadow region is significantly reduced, thereby increasing the time for trapping a particle. This in turn increases the likelihood of actually trapping a particle.

[0065] In an embodiment, it is alternatively or additionally preferred that the ratio of the inner diameter of the further portion to the inner diameter of the first portion is (a) 1.1 or more, preferably 1.15 or more, preferably 1.2 or more, preferably 1.3 or more, preferably 1.4 or more, preferably 1.5 or more, preferably 1.6 or more, preferably 1.8 or more, preferably 2.0 or more, preferably 2.5 or more, preferably 3.0 or more, preferably 3.5 or more, preferably 4.0 or more, preferably 4.5 or more, (b) 5 or less, preferably 4 or less, preferably 3.5 or less, preferably 3 or less, preferably 2.8 or less, preferably 2.5 or less, preferably 2.0 or less, preferably 1.7 or less, preferably 1.5 or less, preferably 1.3 or less, and / or (c) between 1.1 and 5.0, preferably between 1.2 and 4.0, preferably between 1.2 and 3.0, preferably between 1.2 and 2.5, preferably between 1.2 and 2.0, preferably between 1.2 and 1.7;

[0066] and / or

[0067] The transition from the further portion to the first portion is designed in the form of a stepped transition and / or in the form of a conical transition portion, in particular having a conical shape and / or being arranged between the further portion and the first portion, wherein preferably the length of the conical transition portion in the axial direction is (a) 1 mm or more, preferably 3 mm or more, preferably 5 mm or more, preferably 10 mm or more, preferably 20 mm or more, preferably 30 or more, preferably 40 mm or more, preferably 50 mm or more, preferably 60 mm or more, preferably 70 mm or more, (b) 100 mm or less, preferably 90 mm or less, preferably 80 mm or less, preferably 70 mm or less, preferably 60 mm or less, preferably 50 mm or less, preferably 40 mm or less, preferably 30 mm or less, preferably 20 mm or less, preferably 10 mm or less, preferably 5 mm or less, and / or (c) between 1 and 100 mm, preferably between 2 and 90 mm, preferably between 2 and 70 mm, preferably between 2 and 50 mm, preferably between 3 and 30 mm, preferably between 5 and 20 mm.

[0068] It has been shown that a transition, such as a conical transition, provides an improved radial velocity, thereby improving the trapping of particles.

[0069] This problem is solved by the third aspect according to the present application, wherein a refractory tube, in particular for a glass tube drawing process, is proposed, into which the sleeve shaft according to the second aspect of the present application is inserted, in particular in a coaxial manner, wherein preferably the refractory tube has at least one outer surface comprising platinum and / or at least one platinum alloy.

[0070] If the refractory tube is provided with a corresponding sleeve shaft, the advantages of the sleeve shaft as described above with respect to the second aspect of the present application can be applied without any further effort.

[0071] The outer surface of the refractory tube comprising platinum and / or at least one platinum alloy provides a heat-resistant surface. This is particularly preferred for the contact surface of the molten glass flowing on the refractory tube.

[0072] In an embodiment, it is alternatively or additionally preferred that the total axial length L of the inlay, the heat resistance parameter γ of at least one portion of the material of the inlay, and the axial distance d between the location of the molten glass flow onto the refractory tube and the end of the refractory tube from which the glass tube is drawn satisfy the following condition:

[0073]

[0074] wherein the heat resistance parameter γ is defined as

[0075]

[0076] E(T) is the Young's modulus of the metallic material comprised by the inlay at temperature T, and wherein the location of the molten glass flow onto the refractory tube is defined as the center of the axial extension of the shell of the refractory tube.

[0077] More preferably, the total axial length L of the inlay satisfies the condition L < 13 γd More preferably, the total axial length L of the inlay satisfies the condition L < 10 γd More preferably, the total axial length L of the inlay satisfies the condition L < 8 γd More preferably, the total axial length L of the inlay satisfies the condition L < 6 γd Even more preferably, the total axial length L of the inlay satisfies the condition L < 5 γd Even more preferably, the total axial length L of the inlay satisfies the condition L < 4 γd Even more preferably, the total axial length L of the inlay satisfies the condition L≤3γd. Even more preferably, the total axial length L of the inlay satisfies the condition L≤2γd. Even more preferably, the total axial length L of the inlay satisfies the condition L≤γd.

[0078] The part of the inlay closer to the position where the molten glass flows onto the refractory tube (or its housing) is exposed to increased heat compared to the part of the inlay further away from this particular position. With increasing heat, the number of particles originating from the inlay material itself can also increase. Thus, increasing the inlay length brings positive effects, e.g. providing more space for collecting particles. However, once the inlay is inserted into the sleeve shaft of the refractory tube, a negative effect of increasing particle generation can be brought about. Because the additional particles can cause further contamination of the fluid flowing through the sleeve shaft.

[0079] It has been found that a preferred maximum total axial length of the inlay can be determined if the heat resistance of the inlay material is taken into account. Surprisingly, the heat resistance can be expressed in a simple parameter based essentially on the Young's modulus of the metallic material of the inlay.

[0080] This approach is based on the finding that the Young's modulus generally decreases with increasing temperature and thus provides a good basis for assessing the quality of a metallic material in the case of heat exposure.

[0081] It has further been found in this connection that a reliable overall estimate can be made if the Young's modulus at a temperature of 1300 °C and 300 °C is taken into account. This is because it can be assumed that the respective temperature ranges approximately cover the temperatures of the molten glass during its presence on the refractory tube.

[0082] If the total axial length of the inlay is chosen so as to meet the specified condition, a preferred compromise between an increased capture volume on the one hand and an increased particle generation rate on the other hand can be achieved.

[0083] Preferred features

[0084] The following discloses preferred features of the inlay of the first aspect and the sleeve shaft of the second aspect of the present application. These features can be used individually or in any combination.

[0085] Inlay

[0086] Preferably, the total axial length of the inlay is between 50 and 400 mm, preferably between 80 and 350 mm, preferably between 80 and 300 mm, preferably between 80 and 250 mm, preferably between 100 and 200 mm, preferably between 100 and 180 mm.

[0087] Preferably, the total axial length of the inlay is 50 mm or more, preferably 80 mm or more, preferably 100 mm or more, preferably 150 mm or more, preferably 170 mm or more.

[0088] Preferably, the total axial length of the inlay is 400 mm or less, preferably 350 mm or less, preferably 250 mm or less, preferably 200 mm or less, preferably 180 mm or less, preferably 150 mm or less. Preferably 130 mm or less, preferably 110 mm or less, preferably 90 mm or less.

[0089] For example, the total axial length of the inlay is 100 mm, 177 mm or 180 mm.

[0090] Preferably, the inner diameter of the inlay is constant.

[0091] Preferably, the value of the at least one inner diameter of the inlay is between 10 and 50 mm, preferably between 20 and 40 mm, preferably between 30 and 40 mm.

[0092] Preferably, the value of the inner diameter or at least one inner diameter of the inlay is 10 mm or more, preferably 15 mm or more, preferably 20 mm or more, preferably 25 mm or more, preferably 30 mm or more, preferably 35 mm or more, preferably 40 mm or more.

[0093] Preferably, the value of the inner diameter or at least one inner diameter of the inlay is 50 mm or less, preferably 45 mm or less, preferably 40 mm or less, preferably 35 mm or less, preferably 30 mm or less, preferably 25 mm or less, preferably 20 mm or less, preferably 15 mm or less.

[0094] For example, the value of the at least one inner diameter of the inlay is 20 mm or 35 mm.

[0095] The inner surface of the inlay can be the surface of the area of the cylindrical form of the inlay.

[0096] Preferably, the value of the inner surface of the inlay is between 5000 and 25000 mm 2 , preferably between 5000 and 10000 mm 2 or between 15000 and 25000 mm 2 , in particular between 19000 and 23000 mm 2 .

[0097] Preferably, the value of the inner surface of the inlay is 5000 mm 2 or more, preferably 10000 mm 2 or more, preferably 15000 mm 2 or more, preferably 19000 mm 2 or more, preferably 21000 mm 2 or more, preferably 23000 mm 2 or more.

[0098] Preferably, the value of the inner surface of the inlay is 25000 mm 2 Preferably, the value of the inner surface of the inlay is 23000 mm 2 Preferably, the value of the inner surface of the inlay is 21000 mm 2 Preferably, the value of the inner surface of the inlay is 20000 mm 2 Preferably, the value of the inner surface of the inlay is 18000 mm 2 Preferably, the value of the inner surface of the inlay is 15000 mm 2 Preferably, the value of the inner surface of the inlay is 12000 mm 2 Preferably, the value of the inner surface of the inlay is 10000 mm 2 Preferably, the value of the inner surface of the inlay is 10000 mm

[0099] For example, the value of the inner surface of the inlay is 6280 mm 2 , 19782 mm 2 , 19452.3 mm 2 or 22608 mm 2 .

[0100] For example, it can be preferred that the ratio of the value of the inner surface of the sleeve shaft to the value of the inner surface of the inlay.

[0101] Preferably, the value of the ratio is between 5 and 100, in particular between 10 and 20, between 15 and 30, between 30 and 50, between 40 and 50, between 50 and 60, between 60 and 70, between 70 and 80, between 80 and 90 or between 90 and 100.

[0102] Preferably, the value of the ratio is above 5, preferably above 10, preferably above 15, preferably above 20, preferably above 30, preferably above 40, preferably above 50, preferably above 60, preferably above 70, preferably above 80.

[0103] Preferably, the value of the ratio is below 100, preferably below 80, preferably below 70, preferably below 50, preferably below 40, preferably below 30, preferably below 25, preferably below 20, preferably below 15, preferably below 10, preferably below 8, preferably below 5, preferably below 3.

[0104] For example, the value of the ratio can be 14, 20, 22, 24 or 68.

[0105] Sleeve shaft

[0106] Preferably, the total axial length of the sleeve shaft is between 2000 and 4000 mm, preferably between 2200 and 3500 mm, preferably between 2400 and 3100 mm, preferably between 2600 and 3000 mm.

[0107] Preferably, the total axial length of the sleeve shaft is 2000 mm or more, preferably 2200 mm or more, preferably 2400 mm or more, preferably 2600 mm or more, preferably 2800 mm or more.

[0108] Preferably, the total axial length of the sleeve shaft is 4000 mm or less, preferably 3500 mm or less, preferably 3300 mm or less, preferably 3100 mm or less, preferably 2800 mm or less, preferably 2500 mm or less, preferably 2300 mm or less, preferably 2100 mm or less.

[0109] For example, the total axial length of the sleeve shaft can be 3000 mm, 3020 mm, 2460 mm, 2770 mm, 2970 mm, 2460 mm or 2600 mm.

[0110] For example, the first region of the inner surface of the sleeve shaft is the surface of the portion of the sleeve shaft of constant inner diameter. This can be the respective diameter of the inlay insertion or of the hole which can be inserted into the sleeve shaft.

[0111] The axial length of the respective portion of the sleeve shaft of constant inner diameter can be between 1800 and 2200 mm, preferably between 1900 and 2100 mm, in particular 2000 mm.

[0112] Preferably, the value of the constant inner diameter is between 30 and 180 mm, preferably between 30 and 130 mm, preferably between 50 and 100 mm, preferably between 30 and 60 mm, preferably between 35 and 50 mm, preferably between 40 and 50 mm.

[0113] Preferably, the value of the constant inner diameter is 30 mm or more, preferably 35 mm or more, preferably 40 mm or more, preferably 45 mm or more, preferably 50 mm or more, preferably 55 mm or more, preferably 60 mm or more, preferably 70 mm or more, preferably 80 mm or more, preferably 90 mm or more, preferably 100 mm or more, preferably 150 mm or more.

[0114] Preferably, the value of the constant inner diameter is 180 mm or less, preferably 150 mm or less, preferably 130 mm or less, preferably 100 mm or less, preferably 90 mm or less, preferably 80 mm or less, preferably 75 mm or less, preferably 70 mm or less, preferably 65 mm or less, preferably 60 mm or less, preferably 55 mm or less, preferably 50 mm or less, preferably 45 mm or less.

[0115] For example, the value of the constant inner diameter can be 40 mm, 50 mm or 80.5 mm

[0116] The inner surface of the sleeve shaft can be the inner surface of the bore of the sleeve shaft.

[0117] Preferably, the inner surface of the sleeve shaft has a value between 250000 and 500000 mm 2 , preferably between 300000 and 500000 mm 2 , preferably between 350000 and 450000 mm 2 , preferably between 370000 and 430000 mm 2 .

[0118] Preferably, the inner surface of the sleeve shaft has a value of 250000 mm 2 or more, preferably 300000 mm 2 or more, preferably 320000 mm 2 or more, preferably 350000 mm 2 or more, preferably 380000 mm 2 or more, preferably 420000 mm 2 or more, preferably 450000 mm 2 or more.

[0119] Preferably, the inner surface of the sleeve shaft has a value of 500000 mm 2 or less, preferably 480000 mm 2 or less, preferably 450000 mm 2 or less, preferably 400000 mm 2 or less, preferably 380000 mm 2 or less, preferably 350000 mm 2 or less, preferably 320000 mm 2 or less, preferably 300000 mm 2 or less.

[0120] For example, the inner surface of the sleeve shaft can have a value of 423900 mm 2 , 474140 mm 2 , 386220 mm 2 , 434890 mm 2 , 466290 mm 2 , 308976 mm 2 or 326560 mm 2 .

[0121] Further preferred features

[0122] Preferably, the ratio of the overall axial length of the sleeve shaft to the overall axial length of the inlay is between 2 and 80, preferably between 5 and 60, preferably between 5 and 50, preferably between 10 and 35, preferably between 10 and 20 or between 25 and 35.

[0123] Preferably, the ratio of the constant inner diameter of the sleeve shaft to the inner diameter or at least one inner diameter of the inlay is between 2 and 100, preferably between 5 and 80, preferably between 10 and 75, preferably between 20 and 50, preferably between 30 and 40.

[0124] The main particle portion can occur at glass run-up level (glass temperature of about 1200-1300°C) in the hottest region of the refractory tube. However, the inlay, which extends into the sleeve shaft bore into this region, will generate a large number of particles from its inner surface (at these temperatures, the choice of the steel grade of the scale stop has virtually no influence thereon).

[0125] On the other hand, the temperature of the sleeve shaft in the head region (glass temperature of about 900°C) is much lower. It is even the location where the temperature inside the sleeve shaft can be the lowest, and thus also the location where the particle generation rate of the inner surface of the scale stop can be the lowest.

[0126] It can thus be most preferred to select the overall axial length of the inlay to be relatively small. For example, the inlay can not reach the region (inside the sleeve shaft) where the hot glass stream to the outer surface of the refractory tube. For example, the inlay can be arranged in the head portion of the refractory tube.

[0127] Due to the temperature profile inside the sleeve shaft along its axis, an inlay which extends further into the sleeve shaft bore can be bent (air flow conditions worsen) or at least be under tension due to thermal expansion of the different components (which is not desirable).

[0128] The inlay can be designed, for example, not to be conical. BRIEF DESCRIPTION OF DRAWINGS

[0129] Various aspects of the present application will be apparent from the following detailed description of the preferred embodiments, when read in connection with the accompanying drawings, in which

[0130] Figure 1 a cross-sectional view of a first sleeve shaft with a first inlay according to the present application is shown;

[0131] Figure 2 only a cross-sectional view of Figure 1 a first inlay is shown;

[0132] Figure 3 a cross-sectional view of a second sleeve shaft with a second inlay according to the present application is shown;

[0133] Figure 4 a cross-sectional view of a third sleeve shaft with a third inlay according to the present application is shown;

[0134] Figure 5 a cross-sectional view of a fourth sleeve shaft with a fourth inlay according to the present application is shown;

[0135] Figure 6 a simulated pressure distribution and streamlines of a fluid flowing within a sleeve shaft into which an inlay according to the present application is inserted is shown;

[0136] Figure 7a a simulated velocity magnitude of a fluid flow within a sleeve shaft into which an inlay according to the present application is inserted is shown; and

[0137] Figure 7b a cross-sectional view of a first sleeve shaft 1 with a first inlay 3 according to the present application is shown, which is used for at least partially collecting particles of a material originating from the sleeve shaft 1. Figure 7a a detail view of a region of the radial velocity of a fluid flowing within the sleeve shaft 1. DETAILED DESCRIPTION

[0138] Figure 1 a cross-sectional view of a first sleeve shaft 1 with a first inlay 3 according to the present application is shown, which is used for at least partially collecting particles of a material originating from the sleeve shaft 1.

[0139] At least one fluid can flow through the sleeve shaft 1 in an axial direction R parallel to the main extension of the sleeve shaft 1.

[0140] The inlay 3 comprises a first wall portion 5.

[0141] The inlay 3 is partially inserted into the sleeve shaft 1 such that at least a portion of the first wall portion 5 has a radial distance D to at least one first region 7 of the inner surface 9 of the sleeve shaft 1. Thus, the inlay 3 together with the first region 7 of the inner surface 9 of the sleeve shaft 1 encloses a volume domain 11. The volume domain 11 is limited in the axial direction R by a limiting element 13 comprised by the inlay 3. The volume domain 11 is at least partially in the form of an annular volume. The limiting element 13 is arranged at an end portion of the first wall portion 5.

[0142] The inlay 3 further comprises a stop element 15. The stop element 15 allows for an easy arrangement of the inlay 3 within the sleeve shaft 1. The stop element 15 is designed integrally with the limiting element 13.

[0143] From Figure 1 It is apparent that the inlay 3 comprises a cylindrical form region 17 and that a first shell 19 of a first portion 21 of the cylindrical region 17 comprises the first wall portion 5. In Figure 1 In particular, the first portion 21 is identical to the first wall portion 5, however, this is generally not required. The first portion 21 comprises a first end portion 23 of the inlay 3.

[0144] The sleeve shaft 1 and the inlay 3 are arranged coaxially. The inlay 3 is preferably connected to the sleeve shaft 1 in a welded manner, although other types of connection are possible.

[0145] Figure 2 Only a cross-sectional view of a first inlay 3 is shown. The inlay 3 can be inserted into the sleeve shaft 1 as described above with respect to Figure 1 .

[0146] Figure 3 A cross-sectional view of a second sleeve shaft 1'with a second inlay 3' according to the present application is shown for at least partially collecting particles of material originating from the sleeve shaft 1 '.

[0147] Indeed, the sleeve shaft 1'and the inlay 3' are similar to the sleeve shaft 1 and the inlay 3, respectively, as described above with respect to Figure 1 and Figure 2 . Therefore, for identical structural features, the same reference signs are used, however with a single prime. Thus, it is also sufficient to only describe the differences between the sleeve shaft 1' / inlay 3' and the sleeve shaft 1 / inlay 3, while the rest can be referred to the description above with respect to Figure 1 and Figure 2 the sleeve shaft 1 / inlay 3.

[0148] In contrast to the inlay 3, here, for the inlay 3', the stop element 15' is not designed integrally with the limiting element 13'. Moreover, the stop element 15' is separate from the limiting element 13' and is provided at an end portion of the inlay 3' opposite to the first wall portion 5'.

[0149] From Figure 3 it is apparent that, for the inlay 3' (in contrast to the above-described inlay 3), there is also a second shell 25' of at least a second portion 27' of the cylindrical region 17' which is different from the first portion 21' of the cylindrical region 17'. The second shell 25' comprises a second wall portion 29', wherein a first outer diameter OD1' of the first wall portion 5' is smaller than a second outer diameter OD2' of the second wall portion 29'. In Figure 3 , the second portion 27' is identical to the second wall portion 29'.

[0150] The second wall portion 29' contacts at least one region of the inner surface 9' of the sleeve 1 '.

[0151] Figure 4 A cross-sectional view of a third sleeve shaft 1 '' with a third inlay 3'' according to the present application is shown for at least partially collecting particles of material originating from the sleeve shaft 1 ''.

[0152] Indeed, the sleeve shaft 1 '' and the inlay 3'' are similar to the sleeve shaft 1 and the inlay 3, respectively, as described above with respect to Figure 3The sleeve shaft 1'and the inlay 3'are described above. Thus, for identical structural features, the same reference signs are used, however with a double prime. Thus, it is sufficient to only describe the differences between the sleeve shaft 1'' / inlay 3'' and the sleeve shaft 1 ' / inlay 3 ', while the rest can be referred to as above in connection with Figure 3 the description of the sleeve shaft 1 ' / inlay 3 '.

[0153] Contrary to the inlay 3 ', here, for the inlay 3'', the inlay 3'' does not comprise a stop element. The second portion 27'' comprises a second end portion of the inlay 3'', wherein the second portion 27'' is axially subsequent to the first portion 21''. Indeed, the second end portion of the inlay 3'' is at the opposite end of the inlay 3'' compared to the first end portion 23'' of the inlay 3''. The inlay 3'' is entirely within the sleeve shaft 1''. Of course, this is not generally mandatory.

[0154] In Figure 4 the description of the sleeve shaft 1'' / inlay 3'', the sleeve shaft 1'' is shown with a particle 31'' moving along the inner surface 9'' of the sleeve shaft 1'' or already captured in the volume domain 1 1''.

[0155] Figure 5 A cross-sectional view of a fourth sleeve shaft 1''' with a fourth inlay 3''' according to the present application for at least partially collecting particles of material originating from the sleeve shaft 1''' is shown.

[0156] Indeed, the sleeve shaft 1''' and the inlay 3''' are similar to the sleeve shaft 1'' and the inlay 3'' described above in connection with Figure 3 the description of the sleeve shaft 1 ' / inlay 3 '. Thus, for identical structural features, the same reference signs are used, however with a triple prime. Thus, it is sufficient to only describe the differences between the sleeve shaft 1''' / inlay 3''' and the sleeve shaft 1 ' / inlay 3 ', while the rest can be referred to as above in connection with Figure 3 the description of the sleeve shaft 1 ' / inlay 3 '.

[0157] Contrary to the inlay 3 ', here, for the inlay 3''', the stop element 15''' is designed integrally with the second wall portion 27'''.

[0158] The inlay 3''' further comprises a distance element 33''' for firmly arranging the inlay at the sleeve shaft 1'''.

[0159] Figure 6 A simulated pressure distribution of a fluid flowing within a sleeve shaft 35 into which an inlay 37 of a preferred embodiment of the present application is inserted and streamlines of the fluid flow are shown. The pressure distribution is indicated by the respective shape (hatching), the streamlines of the fluid flow are indicated by Figure 6 the respective lines within the sleeve shaft.

[0160] ForFigure 6 The sleeve shaft with the inserted inlay obviously has an advantageous pressure distribution. In particular, at position 39, i.e. at the inner surface of the sleeve shaft near the end of the inlay 37, a positive pressure exists. This leads to a smooth fluid flow from the larger volume enclosed by the sleeve shaft 35 to the smaller volume enclosed by the inlay 37. The smooth fluid flow is also indicated by the corresponding smooth streamlines. In particular, the streamlines are not interrupted in the transition area from the larger volume to the smaller volume. Thus, a negative pressure is avoided at position 39 and the fluid flow is improved.

[0161] The sleeve shaft 35 and the inlay 37 are designed to comply with the proposed geometrical properties in order to achieve an advantageous pressure distribution and fluid flow.

[0162] Figure 7a A simulation of the fluid flow within the sleeve shaft 35 with the inserted inlay 37 according to another preferred embodiment of the present application is shown. The velocity magnitude is indicated by the corresponding shape (hatching). Furthermore, the streamlines of the fluid flow are indicated by the corresponding lines within the sleeve shaft 35.

[0163] Since the sleeve shaft and the inlay are similar in Figure 6 and Figure 7a , the same reference signs are used.

[0164] Also for the sleeve shaft 35 and the inlay 37 in Figure 7a , an advantageous positive pressure and smooth streamlines exist at position 39. In addition, near the inner surface 41 of the sleeve shaft 35, the absolute velocity of the fluid is very small. Thus, the chance of actually capturing a particle that has approached the inner surface 41 within the volume enclosed between the sleeve shaft 35 and the inlay 37 is improved.

[0165] Figure 7b A detail view of the area indicated with a rectangle in Figure 7a is shown. In Figure 7b , the radial velocity of the fluid flowing within the sleeve shaft is indicated by the corresponding shape (hatching). At the corner 43, a high radial velocity exists, which supports the particles to reach the volume enclosed between the sleeve shaft 35 and the inlay 37, where the particles are captured.

[0166] Therefore, it is preferred that the sleeve shaft 35 has an increasing inner diameter from left to right in Figure 7a and Figure 7b .

[0167] Thus, Figure 6 , 7a and 7b show that the proposed sleeve shaft with inlay can provide a positive pressure at the end of the inlay and / or increase the time of capturing particles.

[0168] The features disclosed in the specification, the drawings and the claims are essential to the invention in its various embodiments alone or in each combination.

[0169] List of reference signs

[0170] 1, 1', 1'', 1''' sleeve shaft

[0171] 3, 3', 3'', 3''' insert

[0172] 5, 5', 5'', 5''' first wall portion

[0173] 7, 7', 7'', 7''' first region

[0174] 9, 9', 9'', 9''' inner surface

[0175] 11, 11', 11'', 11''' volume field

[0176] 13, 13', 13'', 13''' limiting element

[0177] 15, 15', 15''' stop element

[0178] 17, 17', 17'', 17''' region

[0179] 19, 19', 19'', 19''' first housing

[0180] 21, 21', 21'', 21''' first portion

[0181] 23, 23', 23'', 23''' first end portion

[0182] 25', 25'', 25''' second housing

[0183] 27', 27'', 27''' second portion

[0184] 29', 29'', 29''' second wall portion

[0185] 31'' particle

[0186] 33''' element

[0187] 35 sleeve shaft

[0188] 37 insert

[0189] 39 position

[0190] 41 surface

[0191] 43 corner

[0192] R, R', R", R'" direction

[0193] D, D', D", D'" distance

[0194] OD1', OD1", OD1'" first outer diameter

[0195] OD2', OD2", OD2'" second outer diameter

Claims

1. A sleeve shaft, comprising: at least one inlay for at least partially collecting particles originating from the material of the sleeve shaft, wherein at least one fluid is able to flow through the sleeve shaft in an axial direction parallel to the main extension of the sleeve shaft, wherein the inlay comprises at least one first wall portion, wherein the inlay is at least partially inserted into the sleeve shaft such that at least one portion of the first wall portion has a radial distance to at least one first region of the inner surface of the sleeve shaft and, thus, the inlay together with the first region of the inner surface of the sleeve shaft encloses at least one volume domain which is limited in the axial direction by limiting elements comprised by the inlay, and wherein the first region of the inner surface of the sleeve shaft is the inner surface of a first portion of the sleeve shaft, the inner diameter of which is larger than the inner diameter of another portion of the sleeve shaft, which follows the first portion of the sleeve shaft in a direction opposite to the axial direction.

2. The sleeve shaft according to claim 1, wherein, The sleeve shaft and the inlay are arranged in a coaxial manner.

3. The sleeve shaft according to claim 1 or 2, wherein the sleeve shaft comprises at least one steel as a material.

4. The sleeve shaft according to claim 1 or 2, wherein the sleeve shaft comprises chromium-nickel steel and / or 2.4633 steel as a material.

5. The sleeve shaft according to claim 1 or 2, wherein, the inlay is arranged at the sleeve shaft by means of at least one fixing device.

6. The sleeve shaft according to claim 1 or 2, wherein the inlay is connected to the sleeve shaft in a welded manner, form-locked manner and / or frictionally engaged manner.

7. The sleeve shaft according to claim 1 or 2, wherein the inlay is arranged at the sleeve shaft by means of at least one fixing device, which is comprised by the inlay.

8. The sleeve shaft according to claim 1 or 2, wherein the inlay comprises at least one region in the form of a cylinder and the shell of at least one portion of the cylindrical region comprises at least one second wall portion, wherein the second wall portion contacts at least one region of the inner surface of the sleeve shaft.

9. The sleeve shaft according to claim 1 or 2, wherein the ratio of the inner diameter of the other portion to the inner diameter of the first portion is 1.1 or more.

10. The sleeve shaft according to claim 1 or 2, wherein, the ratio of the inner diameter of the other portion to the inner diameter of the first portion is 1.4 or more.

11. The sleeve shaft according to claim 1 or 2, wherein the ratio of the inner diameter of the other portion to the inner diameter of the first portion is 5 or less.

12. The sleeve shaft according to claim 1 or 2, wherein, the ratio of the inner diameter of the other portion to the inner diameter of the first portion is 3 or less.

13. The sleeve shaft according to claim 1 or 2, wherein the ratio of the inner diameter of the other portion to the inner diameter of the first portion is between 1.1 and 5.

0.

14. The sleeve shaft according to claim 1 or 2, wherein the transition from the other portion to the first portion is designed in the form of a stepped transition and / or in the form of a conical transition portion.

15. The sleeve shaft according to claim 1 or 2, wherein, the transition from the other portion to the first portion is designed in the form of a conical transition portion, which has a conical shape.

16. The sleeve shaft according to claim 15, wherein the axial length of the conical transition portion is 1 mm or more.

17. The sleeve shaft according to claim 15, wherein the axial length of the conical transition portion is 100 mm or less.

18. The sleeve shaft according to claim 15, wherein the axial length of the conical transition portion is between 1 and 100 mm.

19. A refractory tube into which a sleeve shaft according to any one of claims 1 to 18 is inserted.

20. The refractory tube according to claim 19, wherein the sleeve shaft is inserted into the refractory tube in a coaxial manner.

21. The refractory tube according to claim 19 or 20, wherein the refractory tube is used in a drawing process of a glass tube.

22. The refractory tube according to claim 19 or 20, wherein the refractory tube has at least one outer surface comprising platinum and / or at least one platinum alloy.

23. The refractory tube according to claim 19 or 20, wherein the total axial length L of the inlay, the heat resistance parameter γ of at least one portion of the material of the inlay and the axial distance d between the location at which the molten glass stream is applied onto the refractory tube and the end of the refractory tube from which the glass tube is drawn satisfy the following condition: wherein the heat resistance parameter γ is defined as E(T) is the Young's modulus of the metallic material comprised by the inlay at temperature T, and wherein the location at which the molten glass stream is applied onto the refractory tube is defined as the center of the axial extension of the shell of the refractory tube.

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