Bushing base plate and process of preparing same

Abstract: A bushing base plate comprising a bushing base raw plate (11) having a circular or irregular aperture and a hollow tube (13) having an outer diameter portion larger than the inner diameter of the aperture which is inserted into the aperture and fixed to the bushing base raw plate (11), that are bonded by means of thermal diffusion, and a process of preparing the said bushing plate. The hollow tube (13) may have an outer tapered or rounded surface for strengthening the bonding. The bushing base plate enables the stable spinning of glass fibers or the like because the bonding between the hollow tube (13) and the bushing base raw plate (11) is secured.

Description: Background of the invention This invention relates to a bushing base plate for spinning glass fibers or continuous glass filaments. Several plates are currently employed as a bushing base plate. Generally, the bush base plate is prepared by conducting a perforation treatment of a bashing base raw plate and inserting a hollow tube processed in advance to the shape of a pipe into the aperture of the raw plate and bonded by means of welding. Another bushing base plate which is prepared by compressing raw material having a plate thickness thicker than that of a final product by means of rolling or pressing to extrude a projection, and thereafter conducting a perforation treatment to the extruded projection by means of pressing is also employed. A glass fiber of thin denier and an effective production thereof by making many holes in a certain area with smaller pitches are demanded and a bushing base plate satisfying these requirements is highly requested. The document WO-A-82/01510 discloses a bushing base plate structure wherein a flanged hollow tube is inserted through an aperture in a bushing base raw plate and thereafter the flange of the tube is welded to the bushing base plate. The suitable welding techniques include the so-called HIP (Hot Isostatic Pressure) welding. When conventionally welding is conducted by making an aperture through the bushing base raw plate and inserting the hollow tube processed in advance to the shape of a pipe into the aperture of the raw plate, the bushing base raw plate 1 and the hollow tube 3 having a flow-out aperture 2are as shown in Fig.1 are welded at the base end of the hollow tube 3 by means of razor or plasma or resistive welding. In this case, the hollow tube 3 in the shape of a pipe is finished so as to have a thin wall due to the spinning conditions of glass fibers. When the hollow tube is welded to the position perforated through the bushing base raw plate 1, the welding is performed at the base end 3a of the hollow tube 3 that is the flow-in side of the glass as shown in Fig.1. Since the wall thickness of the hollow tube 3 is thinner than the thickness of the bushing base raw plate 1, the size of the flow-out aperture is small and the pitch between two adjacent flow-out apertures is small so that the whole thickness of the bushing base raw plate 1 is difficult to be welded, only an upper portion of the raw plate 1 is welded as shown in Fig.1. Because of this partial welding, the flow-out aperture is difficult to be processed to the shape which fits the flow conditions of glass or the spinning conditions. When the thus manufactured bushing base plate 4 is employed successively for a long period of time at a high temperature, a creep strain is produced in the bushing base plate 4 receiving a pressure P of glass to be entirely deformed so as to have a swelling as shown in Fig.2. Fig.3 is an enlarged view showing the above fitting portion of the hollow tube 3. Due to the creep deformation of the bushing base raw plate 1, a space is formed between the raw plate 1 and the hollow tube 3 to produce a crack at the above welded portion so that a drawback of enabling the glass fiber spinning because of the leakage of glass liquid. In the worst case, the hollow tube 3 may fall off. This drawback is critical because even when only one of the flow-out apertures is cracked or falls off, an expensive Pt alloy bushing can be no longer employed so as to stop the production or the bushing with the defect may largely influence the quality and the cost of the glass fibers. It is a problem to be solved how to provide a bushing in which cracking and the falling off are difficult to occur. A new process of preparing a bushing is proposed in Japanese patent application JP-A-4-241105. According to this technique, bonding of a flanged nozzle, fitted into a hole of a base plate is effected by the use of a Pt solder. Thereafter the nozzle is drilled to form a spinning hole therethrough. Summary of the Invention An object of the present invention is to provide a bushing base plate having stabilized bonding strength and a shape suitable for glass spinning conditions such to possess a long life and a process of preparing same. According to a first aspect, this invention provides for a bushing base plate for spinning glass fibers comprising a bushing base raw plate having circular or irregular apertures, each aperture having a hollow tube of outer dimensions larger than the inner dimensions of the aperture press-fitted into the aperture and bonded to the bushing base raw plate over the full axial length of the aperture by thermal diffusion. Each aperture of the bushing base raw plate may be formed in correspondence with a swelling of the plate present on the flow-out side of the aperture. The material of the hollow tube employed herein may be different from that of the bushing base raw plate. According to a second aspect of this invention, the bushing base plate for spinning glass fibers comprises a bushing base raw plate having circular or irregular apertures that have a larger size on the glass flow-in side than on the glass flow-out side and hollow tubes of similar circular or irregular section having a glass flow-out end with an outer size equal or smaller than the size of the apertures on the glass flow-in side and a glass flow-in end with an outer size equal or larger than the size of the apertures on the glass flow-out side, a hollow tube fitted into each aperture of the base raw plate and expanded against the wall of the aperture and bonded thereto over the full axial length of the aperture by thermal diffusion. According to a third aspect of the invention, the bushing base plate for spinning glass fibers comprises a bushing base raw plate having circular or irregular apertures that have a tapered or rounded portion of a larger size on the glass flow-in side than the size on the glass flow-out side and hollow tubes of similar circular or irregular section having an outer tapered or rounded glass flow-in end portion and a glass flow-out end portion with an outer size larger than the size of the aperture on the glass flow-out side press fitted into each of said apertures and bonded thereto over the full axial length of the aperture from the tapered or rounded glass flow-in side thereof to the glass flow-out side thereof, by thermal diffusion. The aperture of the bushing base raw plate and the hollow tube may have two or more tapered or rounded portions or two or more steps and the combination of a tapered portion and a rounded portion may be employed in addition to one tapered or rounded portion. If one tapered portion is present, its tapered angle is preferably between 0.1 and 120°, while if two or more tapered portions are present, the tapered angle of at least one of the said tapered portions is preferably between 0.1 and 120°. According to a fourth aspect of the invention, a process of preparing a bushing base plate for spinning glass fiber comprises forming circular or irregular apertures through a bushing base raw plate, press fitting a hollow tube of outer dimensions larger than the dimensions of the apertures into each of the apertures or inserting in each of the apertures a hollow tube and expanding the hollow tube from the inside, and bonding the press-fitted or expanded hollow tube to the bushing base raw plate over the full axial length of the aperture by thermal diffusion. The process may comprise perforating a circular or irregular aperture at the center of a swelling which is formed simultaneously with or before the formation of the said aperture through a bushing base raw plate, inserting a hollow tube into the aperture at a certain interference for fixing the hollow tube to the bushing base raw material, or inserting the said hollow tube and enlarging the hollow tube from the inside to have a desired interference, and bonding the both by means of thermal diffusion. Depending on the case, the bonded hollow tube and the swelling may be molded by means of plastic deformation to have a desired shape and desired dimensions. The material of the hollow tube employed herein may be different from that of the bushing base raw plate. The hollow tube or pipe is in advance processed to suitably possess designated product dimensions by means of an extrusion processing, a press processing or the like or may be processed to dimensions slightly higher or lower than the designated dimensions. The outer shape of the hollow tube is suitable for being inserted into an fixed to the aperture with a certain interference. The hollow tube is inserted into the aperture and fixed to the bushing base raw plate by means of thermal diffusion treatment. The hollow tube may be coaled with base plate raw plate material at the glass flow-out side of the bushing base raw plate for a certain length for reinforcement. The bushing base plate may be molded to have the tapered or rounded shape at the periphery including the bonding boundary of the glass flow-in side and/or glass flow-out side. As the above hollow tube, a tube may be employed having an inner circular section and an outer circular section. As the above hollow tube, a tube may be also employed having an inner irregular section and an outer irregular section. As material of the above bushing base raw plate, a Pt-Rh alloy, a Pt-Rh-Pd alloy, platinum of which grains are stabilized by an oxide, an platinum alloy of which grains are stabilized by an oxide, a Pt-Au alloy, a Pt-Rh-Au alloy or a Pt-Rh-Pd-Au alloy may be employed, and material of the hollow tube, a Pt-Au alloy, a Pt-Rh-Au alloy, a Pt-Rh alloy, a Pt-Rh-Pd alloy, platinum of which grains are stabilized by an oxide or an platinum alloy of which grains are stabilized by an oxide may be employed. The process of preparing a bushing base plate in accordance with the present invention may comprise perforating through a bushing base raw plate an aperture having a circular or irregular section of which an aperture size of its glass flow-in side is larger than that of a glass flow-out side, inserting and fixing to the aperture a hollow tube having a glass flow-out end of which an outer size is the same as or smaller than the above aperture size of the glass flow-in side and a glass flow-in end of which an outer size is larger than the above aperture size of the glass flow-out side and having a circular section when the aperture of the bushing base raw plate is circular or an irregular section when the aperture of the bushing base raw plate is irregular, and performing thermal diffusion for bonding. Another embodiment of the above process of preparing a bushing base plate comprises perforating through a bushing base raw plate a tapered or rounded aperture having a circular or irregular section of which an aperture size of its glass flow-in side is larger than that of a glass flow-out side, inserting from the glass flow-in side to the glass flow-out and fixing to the said aperture a hollow tube having a tapered or rounded upper (glass flow-in) end of which an outer size is larger than the above aperture size of the glass flow-out side and having a circular section when the aperture of the bushing base raw plate is circular or an irregular section when the aperture of the bushing base raw plate is irregular so as to tightly adhere the portion from the tapered or rounded upper end to the lower end thereof of the hollow tube to the whole wall or glass flow-out side wall of the aperture, and performing thermal diffusion for bonding. When the aperture is perforated through the bushing base raw plate in this process of preparing the bushing base plate, a swelling portion surrounding the glass flow-out end of the aperture of the bushing base raw plate may be provided, and the hollow tube may be inserted into and fixed to the swelling portion and be bonded by means of thermal diffusion. The bushing base plate may be prepared by plastically deforming the bonding boundary of the glass flow-in side and/or the glass flow-out side to the tapered or rounded shape after the hollow tube is bonded to the aperture formed through the bushing base plate by means of thermal diffusion. The bushing base plate may be prepared by finishing the shape of the flow-out aperture to a desired shape and desired dimensions by means of the plastic deformation after the hollow tube is bonded to the aperture formed through the bushing base plate by means of thermal diffusion. In this process of preparing the bushing base plate, after the hollow tube is bonded to the aperture formed through the bushing base plate by means of thermal diffusion and the plastic deformation is conducted, one or more thermal diffusions may be repeated. The thermal diffusion may be conducted not only after the completion of the plastic deformation but also in the course of the plastic processing. The thermal diffusion is preferably conducted in a temperature range between 500 °C and a temperature 20 °C lower than the melting point of the material. As mentioned, the bushing base plate of the first invention enables the stable spinning by obtaining a structure in which end breakage is difficult to occur in the spinning generated at a center of densely distributed apertures because neither space nor is present in the bonding portion, the strength of the resulting bushing base plate is the same as that of the mother material to be endured by an operation for a long period of time and the material difficult to be wetted may be employed as the end chip portion. With the process according to the fourth aspect of the invention, a bushing may be obtained which possesses a stable strength and a long life containing a bushing base plate having a plurality of apertures with a small diameter and narrow pitches. Since the wall thickness of the nozzle is thin, densely distributed apertures may be easily mechanically processed without skill, neither space nor is present in the bonding portion, the strength of the resulting bushing base plate is the same as that of the mother material to be endured by an operation for a long period of time and the material difficult to be wetted may be employed as the end chip portion, an apparatus of spinning glass fibers capable of performing stable spinning may be obtained by realizing a structure in which end breakage generated at the center of the densely distributed apertures is difficult to occur during the spinning. According to the invention a bushing is obtained which enables the manufacture of uniform glass fibers having a high precision. Even if deformation of the bushing base plate occurs due to the creep deformation produced by the pressure of glass and a high temperature exposed for a long period of time during the spinning, no space is created between the hollow tube and the bushing base raw plate bonded to each other constituting the glass flow-out aperture so that the crack formation at the welded portion and the falling-off of the hollow tube never occur. Accordingly, the above bushing is safely employed. Brief Description of the Drawings Fig.1 is a sectional view showing one conventional example of the bonding portion between an aperture of a bushing base plate and a hollow tube. Fig.2 is a sectional view showing another modified embodiment of the bushing base plate. Fig.3 is a sectional view showing a space in the bonding portion between an aperture of a conventional bushing base plate and a hollow tube. Fig.4 is a sectional view showing an aperture of a bushing base raw plate of Example 1. Fig.5 is a sectional view showing a hollow tube of Example 1. Fig. 6 is a sectional view showing the bonding portion between the aperture of the bushing base plate and the hollow tube. Fig.7 is a sectional view showing a bushing base raw plate having a swelling of Example 2. Fig.8 is a sectional view showing the bonding portion between the swelling of the raw plate and the hollow tube of Fig.7. Fig.9 is a sectional view showing a bushing base plate of Example 3 prepared by further modifying the bushing base plate of Fig.8. Fig.10 is a sectional view showing the bonding portion between an aperture of a conventional bushing base plate and a hollow tube of another embodiment of Example 3. Fig.11 is a sectional view showing the bonding portion between an aperture of a conventional bushing base plate and a hollow tube of a further embodiment of Example 3. Fig.12 is a sectional view showing a bushing base raw plate having an aperture employed in Example 5. Fig.13 is a sectional view showing one example of a hollow tube employed in Example 5. Fig.14 is a sectional view showing one step of a preparing process of Example 5. Fig.15 is a sectional view showing another step in Example 5. Fig.16 is a sectional view showing a further step in Example 5. Fig.17 is a sectional view showing a hollow tube employed in Example 6. Fig.18 is a sectional view showing the hollow tube and a raw plate combined with each other of Fig.17. Fig.19 is a sectional view showing a bushing base raw plate employed in Example 7. Fig.20 is a sectional view showing the hollow tube and a raw plate combined with each other of Fig.19. Fig.21 is a sectional view showing an alternative embodiment of Fig.20. Example 7. Fig.22 is a sectional view showing a bushing base plate of Example 8. Fig.23 is a sectional view showing a bushing base plate of Example 9. Fig.24 is a sectional view showing an alternative embodiment of Example 9. Fig.25 is a view showing an aperture of a bushing base raw plate of Example 10. Fig.26 is a sectional view showing a hollow tube of Example 10. Fig.27 is a sectional view showing a bushing base plate of Example 10. Fig.28 is a sectional view showing a bushing base raw plate of Example 11. Fig.29 is a sectional view showing a hollow tube of Example 11. Fig.30 is a sectional view showing a bushing base plate of Example 11. Fig.31 is a microphotograph showing a sectional organization of a bushing base plate obtained in Example 11. Detailed Description of the Invention Since the hollow tube constituting the flow-out aperture is inserted into the aperture perforated through the flat plate at a certain interference and fixed to the bushing base raw plate and bonded by means of thermal diffusion in the invention, the metal materials of the both elements diffuse to each other in the outer periphery of the aperture of the bushing base plate side and of the hollow tube under a condition of being fixed and pressed at a certain interference and the two elements are bonded so that its strength is the same as that of the mother material. "A certain interference" employed herein means a difference between the outer diameter of the hollow tube and the inner diameter of the aperture when the former is larger than latter, which produces a pressing force after the insertion and fixation. When the portions to be bonded extend to the whole area and the firm bonding is required, the hollow tube is inserted into and fixed to the aperture of the bushing base raw plate side without the presence of air, another gas or impurities between the aperture and the outer surface of the hollow tube so that the thermal dispersion may be conducted on the whole surface to be bonded. Since, in this way, the same bonding strength as the strength of the mother material may be obtained, neither cracks nor defects can be produced even if the bushing base plate is deformed after it is employed for a long period of time. Since, further, the spinning of the glass fibers is conducted at a temperature of 1100 to 1400 °C, the thermal diffusion further proceeds during the operation so that no lowering of the bonding strength is expected. When a flow-out aperture having a thin wall is required for manufacturing thin glass fibers or the like, the strength of the pipe itself is low, and if the bushing base raw plate and the base end of the pipe are perpendicularly crossed, the weight of the glass and the spinning strength may damage the crossed portion. For reinforcing the crossed portion, a hollow tubular swelling is formed on the bushing base raw plate and a hollow tube or a thin wall pipe is inserted into an aperture perforated through the central portion of the swelling so that the bonding portion of the bushing base raw plate and the pipe constituting the flow-out aperture is guarded by the swelling so as to provide no chance of destruction of this bonding portion. In the present invention, the simple bonding may satisfy the object thereof, or the bonding portion may be further strengthened effectively in view of its shape by molding the shape of the flow-in aperture into which glass flows in by means of plastic processing or by changing the length and the shape of the swelling and the hollow tube. Another hollow tube made of different material may be employed or the material of the flow-out aperture may be that composed of Pt or an Pt alloy and Au alloyed therewith. No lowering of strength is expected. Also according to the process of the invention, the same function as that of the first invention may be realized. However, in the second invention, the hollow tube can also be inserted into the aperture after the tube is enlarged from the inside. As mentioned, in the bushing base plate of the invention, the bushing base raw plate and the hollow tube are tightly fixed to each other by the plastic deformation treatment at the time of inserting the hollow tube into the aperture of which a aperture size of the glass flow-in side is larger perforated through the bushing base raw plate or thereafter, and are bonded by means of the thermal diffusion. The careful inserting operation and the careful plastic deformation processing for eliminating the contamination of gas and impurities enable to maintain the inner aperture surface of the bushing base plate and the outer hollow tube surface clean and to keep them tightly. Since they are subjected to the thermal treatment under the condition that they are fixed under a certain inner pressure, the both metal materials are bonded to each other by means of the mutual diffusion to make the strength the same as that of the original metal material. The plastic deformation processing after the thermal diffusion and the next thermal diffusion enable to obtain not only a firmly bonded product but also a smooth bonded surface at the bonding boundary recognized on the surface. The shape of the hollow tube may be any one of a straight tube, a tapered tube, a rounded tube, and may be one having a tapered or rounded portion at an upper end thereof or one having a stepped portion. In case of the tapered or rounded tube, in order to introduce impurities, a gas and the like between the said tapered portion or rounded portion and the hollow tube to maintain a constant inner pressure both on the clean metal surfaces, it is necessary to make the outer size of a part of the tapered or rounded portion larger than the aperture size of glass flow-out side of the bushing base raw plate. It is necessary to suitably adjust the size of the aperture perforated through the bushing base raw plate and the tapered angle and the rounded portion so as to tightly adhere from the upper portion of the tapered or rounded portion to the lower portion thereof to the whole surface of the aperture of the bushing base raw plate or the aperture wall of the glass flow-out size. When the number of tapers is one, the tapered angles of the aperture of the bushing base raw plate and of the tapered portion formed on the hollow tube is preferably between 0.01 and 120°, and when the the said number is two or more, at lest one of the tapered angles is preferably between 0.01 and 120°. The reasons thereof are that no effect can be produced when the angle is below this value, and the inner diameter of the hollow tube is made to be too small in relation to the diameter of the glass flow-out side of the bushing base plate ordinarily employed considering the relation between the thickness of the bushing base plate and the diameter of the glass flow-out side so as to make the employment of the hollow tube meaningless when the angle exceeds the above value so that no effects may be obtained by the presence of the tapered portion. When the periphery of the hollow tube at the glass flow-out side of the bushing base raw plate is coated with the base plate raw plate material, the bonding between the bushing base raw plate and the hollow tube is made to be stronger. Since the thickness of the bushing base raw plate is made to be as thin as possible in the view point of economy so long as it may be endured, the length may be insufficient required for the bonding but the bonding strength per a flow-out aperture increases with the increase of the bonding area. The most important is that when the bushing base plate is deformed and curved by the pressure of glass after a long period of time of operation, the deformation of the bushing base plate by means of the curvature accompanies the deformation of the aperture due to the bending of the lower portion of the bushing base plate. When in this case the hollow tube is coated for reinforcement, characteristically no deformation is produced at the lower portion bonded to the hollow tube by means of the coating. The sectional shape of the hollow tube employed may be appropriately selected depending on a sectional shape of a glass fiber desired. When the glass fiber having the circular section is desired, the hollow tube having the circular outer and inner shapes is employed. When the glass fiber having the irregular section is desired, the hollow tube having the irregular outer and inner shapes is employed. The irregular shape employed herein is any shape such as a triangle, a square, an ellipse, an oval, a Y-shape and the like other than a circle. In accordance with the process of preparing the bushing base plate of the present invention, the portions to be bonded can be orderly bonded over a whole area. For performing the orderly bonding, the insertion and the fixation are required to be carried out without the introduction of air, another gas and impurities between the aperture of the bushing base raw plate and the outer surface of the hollow tube to be bonded. Since, according to the process of the invention; the wall of the tapered aperture of the bushing base raw plate is tightly adhered to the periphery of the hollow tube while the aperture is rubbed with the top or middle portion of the hollow tube when the hollow tube is inserted into the tapered aperture perforated through the bushing base plate, such an impurity as air, a gas or the like present on the aperture wall is expelled by the top or middle portion of the hollow tube so that the bonding can be carried out under the condition free from these impurities. When the thermal diffusion is performed under the said condition free from the impurities, the thermal diffusion can be completely conducted over the whole area of the bonded portions. Since the same bonding strength as the material strength of the mother material is obtained, neither cracks nor defects are produced even if the bushing base plate is deformed after a long period of time of operation. When the material of at least one of the both members to be bonded (bushing base raw plate and hollow tube) is platinum of which grains are stabilized by an oxide or a platinum alloy of which grains are stabilized by an oxide, this kind of material loses the oxide mainly participating in the reinforcing mechanism which floats to the surface and no stabilized grains exist at the welded portion in case that the welding is employed for the bonding so that the material loses its characteristic as the platinum of which grains are stabilized by an oxide or the platinum alloy of which grains are stabilized by an oxide. Since the considerable lowering of the strength occurs at the bonded portion due to the above reason, a problem arises that the strength at the portion becomes very weak. Since, however, no welding is conducted in the process of the present invention, no lowering of the strength occurs so that the strength at the bonded portion can be the substantially same as that of the raw material. For reinforcing the hollow tube by coating the periphery thereof at the glass flow-out side of the bushing base plate with the base raw plate material, a swelling may be formed surrounding the aperture at the glass flow-out side of the bushing base raw plate when the glass flow-out aperture is produced through the bushing base plate, and when the periphery of the aperture at the glass flow-in side is molded or the flow-out aperture is adjusted to a desired shape and dimensions after the bonding of the hollow tube to the bushing base raw plate, the approach of the bushing base raw plate material to the periphery of the hollow tube may be utilized for forming the above coating of the base raw plate material at the time of forming the taper by employing a mold of which an inlet shape has a taper or a step and which receives the flow-out aperture. The reason why the temperature of thermal treatment is restricted to the range between 500 °C and a temperature 20 °C lower than the melting point of the material is that the diffusion does not occur below 500 °C and the control of the temperature distribution can be performed only in a limited range and the temperature may partially exceed the melting point of the material resulting in the melting of the material if the temperature exceeds the point 20 °C lower than the melting point of the material. The material employed for the bushing base raw plate and for the hollow tube is selected in consideration of the material of melted glass, spinning conditions and an intensity life, and if Au is added to the material of the hollow tube, the material is difficult to be wetted with glass and an end breakage of the glass during the spinning seldom occurs so that the stable spinning may be obtained. Examples Examples of a bushing base plate and its preparation according to the present invention will be described referring to the drawings. However, these Examples do not restrict the present invention. At first, Examples of a bushing base plate and its preparation according to the first and the second inventions will be describes as Examples 1 to 5, and then other Examples according to the third and fourth inventions will be describes as Examples 6 to 12. Example 1 At first, a Pt-Rh (10%) alloy employed as bushing base raw plate material was rolled by means of a rolling machine to a thickness of 1.5 mm and was cut to a piece having a width of 100 mm and a length of 500 mm. Through this raw plate 11, 800 holes were zigzag perforated with a pitch of 3.5mm by means of press processing to make apertures 12 as shown in Fig.4. The size of the aperture through the bushing base plate was 1.9 mm in diameter. A hollow tube 13 as shown in Fig.5 was draw-processed, cut and molded to have an outer diameter of 2.0mm, an inner diameter of 1.5mm, a thickness of 0.25mm and a height of 6.5mm. After this hollow tube 13 was set in the aperture 12, a die of which a dimension was larger than the aperture 12 perforated through the bushing base raw plate 11 by 0.2mm was set under the plate and the hollow tube was inserted into the aperture employing a punch having the same dimension as the outer diameter of the hollow tube 13 as an upper die at an interference of 0.05mm, the thermal diffusion at 1400 °C was conducted for five hours in an electric furnace. It was confirmed that the fixed portion became the same material because the grains at the bushing base plate's aperture 12 side and at the outer perophery of the hollow tube 13 diffused to each other so that the crystal growth spanned the boundary of the bonding and that the bonding was completed over the whole area. A bushing was prepared by bonding the bushing base plate thus obtained to an upper box-like vessel constituting a terminal and a fusion furnace with a filter by means of arc welding. Example 2 During the molding of the above bushing base plate, a swelling 14 having the shape shown in Fig.7 was formed on the bushing base raw plate by means of press processing and an aperture 12 was perforated through the cantral portion thereof. The diameter of the aperture was 1.9mm and the length was 3mm. A hollow tube 13 having an outer diameter of 2.0mm, an inner diameter of 1.5mm and a thickness of 0.25mm was inserted into the aperture 12 at an interference of 0.05mm, and according to the same conditions of Example 1, a bushing plate shown in Fig.8 was obtained. Example 3 In the processes of Examples 1 and 2, the thermal diffusion at 1400 °C was carried out for five hours in an electric furnace and then the plate was molded by means of pressing and by employing a punch having a taper and a die to form a taper of 30 ° at the glass flow-in side and a two step taper at the flow-out side to prepare a similar bushing plate to those of the above Examples. While, in addition, base plates shown in Figs.10 and 11 were prepared by means of molding, they were excellent in the shape and the bonding conditions. Example 4 The same processing as that of Example 3 was performed employing a Pt(95%)-Au(5%) alloy as material of the hollow tube or the flow-out aperture. The reason why 5 % of Au was added was to achieve the improvement of anti-wettability at the time of spinning. The splendid effects for bonding were obtained partially because the diffusion speed of Au was high. Example 5 During the molding of the bushing base plate in Example 1, a swelling 14 having the shape shown in Fig.7 was formed on the bushing base raw plate by means of press processing and an aperture 12 was perforated through the central portion thereof. The diameter of the aperture was 2.5mm and the length was 3mm. A hollow tube 13 having an outer diameter of 2.45mm, an inner diameter of 1.95mm and a thickness of 0.25mm was inserted into the aperture 12, and the inner diameter of the hollow tube was increased to 2.1mm by enlarging the original inner diameter of the hollow tube employing a punch having a top planar bullet like end of which a diameter was 2.1mm in a die which is not shown. The hollow tube was fixed to the aperture 12 at the center of the swelling 14 at a certain inteference and the thermal treatment at 1400 °C was conducted in an electricfurnace for three hours followed by the same preparation processes to obtain a bushing base plate having a section shown in Fig.8. Upon completion of the thermal treatment, a taper of 30° may be formed at the glass flow-in side by means of plastic processing as shown in Fig.9 and the thermal treatment may be repeated. Glass fibers manufactured by employing the respective bushings of Examples 1 to 5 exhibited a longer life than glass fibers manufactured with a conventional bushing. Moreover in Example 4, end breakage during spinning was scarce because the top chip portion was difficult to be wetted. Example 6 At first, a Pt-Rh (10 %) alloy employed as bushing base raw plate material was rolled by means of a rolling machine to a thickness of 1.5 mm and was cut to a piece having a width of 50 mm and a length of 400 mm. Through this raw plate 21, 400 holes were perforated having a circular section by means of press processing as shown in Fig.12. The dimensions were as follows. Diameter of glass flow-in side of the bushing base plate (d 1 ) was 2.5mm, a diameter of a glass flow-out end (d 2 ) was 2.1mm and a tapered angle  1 was 15.2° . A Pt-Au (5%) alloy was processed by drawing and cutting to obtain a pipe-like hollow tube 23 which had, as shown in Fig.13, inner and outer circular shapes of which an outer diameter, an inner diameter and a length were 2.6 mm, 2.0 mm and 6mm, respectively, and had one tapered end having an outer diameter of 1.9 mm formed by means of pressing. The hollow tube 23 shown in Fig.14 was inserted into an aperture perforated through the above bushing base raw plate 1 from its larger diameter side, and fixed thereto as shown in Fig.15. Thereafter, a thermal treatment at 1400 °C was conducted for three hours to bond the bushing base raw plate 21 and the hollow tube 23 by means of thermal diffusion. and the one end of the hollow tube 23 was made back to a straight pipe by plastic deformation to obtain a bushing base plate 24 as shown in Fig.16. The section of the bushing base plate 24 thus obtained was observed with a microscope to find out that the materials of the both of the bushing base raw plate and the hollow tube 23 were diffused through the thermal diffusion at the boundary to constitute an integrated material in which the crystals thereof were intricate and the sufficient metal bonding was obtained. Example 7 A Pt-Rh(10%)-Pd(5%) alloy employed as bushing base raw plate material was rolled by means of a rolling machine to a thickness of 1.5 mm and was cut to a piece having a width of 70 mm and a length of 600 mm. Through this raw plate 21, 800 holes were perforated having a circular section by means of press processing as shown in Fig.12. The dimensions were as follows. d 1 =2.2mm and d 2 =1.6mm, and a tapered angle  1 was 22.6°. A Pt-Rh(10%)-Au(5%) alloy was processed to obtain a pipe-like hollow tube 23 which had, as shown in Fig.17, inner and outer circular shapes in which d 3 =2.4mm, d 4 =1.5mm, a tapered angle  2 is 16°, t 1 =0.2mm and l 1 =6mm. The hollow tube 31 was inserted into an aperture perforated through the above bushing base raw plate 21 and fixed thereto as shown in Fig.18. Thereafter, a thermal treatment at 1200 °C was conducted for six hours to bond the bushing base raw plate 21 and the hollow tube 23 by means of thermal diffusion to obtain a bushing base plate 24. The section of the bushing base plate 24 thus obtained was observed with a microscope to find out that the materials of the both of the bushing base raw plate 21 and the hollow tube 23 were diffused through the thermal diffusion at the boundary to constitute an integrated material in which the crystals thereof were intricate and the sufficient metal bonding was obtained. Example 8 A platinum plate of which grains are stabilized by an oxide prepared by internally oxidizing Pt, bushing base raw plate material, by means of the addition of 0.3 % of Zr was rolled by means of a rolling machine to a thickness of 1.5 mm and was cut to a piece having a width of 70 mm and a length of 600 mm. On this raw plate 31, a hollow tube like swelling having a circular section was formed by means of press processing as shown in Fig.19. The dimensions were as follows. d 6 =2.4mm and d 7 =1.8mm, t 2 =0.5mm, l 2 =3.0mm and  3 =11.4°. A Pt-Zr(0.3%) alloy was processed by drawing and cutting to obtain a hollow tube 33 of which a shape was circular as shown in Fig.13 having an outer diameter of 2.6mm, an inner diameter of 2.0mm and a length of 7mm, and having a tapered end of which an outer dimension was 1.7mm. The hollow tube was inserted into an aperture perforated through the above bushing base raw plate 31 and fixed thereto as shown in Fig.20. Thereafter, a thermal treatment at 1400 °C was conducted for 12 hours to bond the bushing base raw plate 31 and the hollow tube 33 by means of thermal diffusion to obtain a bushing base plate 34. The section of the bushing base plate 34' thus obtained observed with a microscope was as shown in Fig.31 in which the organization of the hollow tube and the bushing base raw plate was identical and no boundary was observed so that the both were bonded more firmly. Example 9 After the periphery of the aperture at the glass flow-in side was processed by pressing to the shape having a tapered angle of 30° employing the bushing base plate shown in Fig.16 obtained in Example 5, the plastic deformation was caused for enlarging the inner diameter by 0.2mm to prepare a bushing base plate 44 as shown in Fig.22. The section of the bushing base plate 44 thus obtained was observed with a microscope to find out that no boundary between the hollow tube 43 and the bushing base raw plate 41 was observed and the sufficient metal bonding was obtained. Example 10 A taper-like plastic deformation was caused by press processing the periphery of the aperture at the glass flow-in side providing as a lower mold at the time of pressing a mold having a taper at the periphery of the inlet for inserting the hollow tube therein as shown in Fig.23 while employing the bushing base plate shown in Fig.16 obtained in Example 5. Thereafter, the thermal diffusion treatment at 1400 °C was again conducted for one hour to obtain a bushing base plate 54 plastically deformed as shown in Fig.24. The bushing base plate 54 thus obtained was covered and reinforced with the bushing base raw plate material at the periphery of the hollow tube of the glass flow-out side of the bushing base raw plate 51. Example 11 The sectional shapes of the apertures perforated through the bushing base raw plate of Example 5 were made to be elliptic as shown in Fig.25 (a) and (b) of which dimensions were as follows. Glass flow-in side: d 8 =1.5mm, d 10 =3.5mm and r 1 =0.75mm. Glass flow-out side: d 9 =1.3mm, d 11 =3.3mm and r 2 =0.65mm. The shape of the hollow tube was made to be one shown in Fig.26 (a), (b) and (c) of which dimensions were as follows. Glass flow-in side: d 12 =1.6mm, d 13 =1.1mm, r 3 =0.8mm, d 14 =3.6mm, d 15 =3.1mm and r 4 =0.55mm. Glass flow-out side: d 16 =1.2mm, d 18 =3.2mm, d 17 =0.7mm, d 19 =2.7mm, r 5 =0.6mm and r 6 =0.35mm. The conditions were the same as those of Example 5 except that the length of the hollow tube was 7mmm and the tube had a taper on the whole length. After the thermal diffusion the periphery of the aperture of te glass flow-in side was press processed to have a taper and the bonded member was thermally treated at 1200 °C for one hour followed by the deformation of the flow-out aperture to a straight one to obtain a bushing base plate 64 as shown in Fig.27. The section of the bushing base plate 64 thus obtained was observed with a microscope to find out that the materials of the both of the bushing base raw plate and the hollow tube 63 were diffused through the thermal diffusion at the boundary to constitute an integrated material in which the crystals thereof were intricate and the sufficient metal bonding was obtained. Example 12 The sectional shape of an aperture perforated through a platinum-rhodium alloy plate of which grains are stabilized by an oxide employed as bushing base raw plate material was that having two-step tapers as shown in Fig.28 and the following dimensions.  1 =90°,  2 =10°. The sectional shape of the hollow tube was that as shown in Fig.29 to have the following dimensions.  3 =85°,  4 =8°, d 3 =3.6mm and d 4 =2.2mm. After the hollow tube was inserted into the aperture of the raw plate 71 and fixed thereto as shown in Fig.30, the thermal treatment was conducted at 1500 °C for one hour for bonding the bushing base raw plate 71 and the hollow tube 73 by means of thermal diffusion to prepare a bushing base plate 74. The section of the bushing base plate 74 thus obtained was observed with a microscope to find out that the materials of the both of the bushing base raw plate and the hollow tube 73 were diffused through the thermal diffusion at the boundary to constitute an integrated material in which the crystals thereof were intricate and the sufficient metal bonding was obtained. A bushing was prepared by bonding the respective bushing base plates obtained in Examples 1 to 12 to an upper box-like vessel constituting a terminal and a fusion furnace with a filter by means of arc welding. While glass fibers were continuously manufactured employing the bushing, no problems were observed after a lapse of half Year in the bushings employing the bushing base plate of Examples 1 to 12.

Claims: A bushing base plate for spinning glass fibers comprising a bushing base raw plate (11, 21, 31, 41, 51, 61, 71) having circular or irregular apertures (12, 22, 32, 42, 52, 62, 72), each aperture having a hollow tube (13, 23, 33, 43, 53, 63, 73) of outer dimensions larger than the inner dimensions of the aperture press-fitted into the aperture and bonded to the bushing base raw plate (11, 21, 31, 41, 51, 61, 71) over the full axial length of the aperture by thermal diffusion. A bushing base plate according to claim 1, characterized in that each aperture of said bushing base raw plate (11, 31, 51) is formed in correspondence with a swelling (14, 37) of the plate present on the flow-out side of the aperture. A bushing base plate as claimed in claim 1, wherein the material of said hollow tubes (13, 23, 33, 43, 53, 63, 73) is different from that of the bushing base raw plate (11, 21, 31, 41, 51, 61, 71). A bushing base plate for spinning glass fibers comprising a bushing base raw plate (11, 21, 31, 41, 51, 61, 71) having circular or irregular apertures (12, 22, 32, 42, 52, 62, 72) that have a larger size on the glass flow-in side (d1, d6, d8, d10) than on the glass flow-out side (d2, d7, d9, d11) and hollow tubes (13, 23, 33, 43, 53, 63, 73) of similar circular or irregular section having a glass flow-out end (d4, d16, d18) with an outer size equal or smaller than the size of the apertures on the glass flow-in side (d1, d6, d10) and a glass flow-in end (d3, d12, d14) with an outer size equal or larger than the size of the apertures on the glass flow-out side, a hollow tube fitted into each aperture of the base raw plate and expanded against the wall of the aperture and bonded thereto over the full axial length of the aperture by thermal diffusion. A bushing base plate for spinning glass fibers comprising a bushing base raw plate (11, 21, 31, 41, 51, 61, 71) having circular or irregular apertures (12, 22, 32, 42, 52, 62, 72) having a tapered or rounded portion of a larger size on the glass flow-in side (d1, d6, d8, d10) than the size on the glass flow-out side (d2, d7, d9, d11) and hollow tubes (13, 23, 33, 43, 53, 63, 73) of similar circular or irregular section having an outer tapered or rounded glass flow-in end (d3, d12, d14) portion and a glass flow-out end (d4, d16, d18) portion with an outer size larger than the size of the aperture on the glass flow-out side (d2, d7, d11) press fitted into each of said apertures and bonded thereto over the full axial length of the aperture from the tapered or rounded glass flow-in side (d1, d6, d8, d10) thereof to the glass flow-out side (d2, d7, d11) thereof by thermal diffusion. The bushing base plate of claim 5, wherein the angle (1-4) of the tapering of the apertures in the bushing base raw plate (11, 21, 31, 41, 51, 61, 71) and of the outer tapered portion of the hollow tubes is between 0.01 ° and 120°. The bushing base plate of claim 5, wherein the apertures through the bushing base raw plate (31, 71) and the hollow tubes (33, 73) have two or more tapered or rounded portions. The bushing base plate of claim 7, wherein the angle (1-4) of at least one of the taperings is between 0.01° and 120°. The bushing base plate of claim 4, wherein the hollow tube at the glass flow-out side of the bushing base plate is surrounded for a certain length by a reinforcing collar (14, 37) of base raw plate material. The bushing base plate of claim 4, wherein the material of the bushing base raw plate (11, 21, 31, 41, 51, 61, 71) is a Pt-Rh alloy, a Pt-Rh-Pd alloy, platinum the grains of which are stabilized by an oxide, a platinum alloy the grains of which are stabilized by an oxide, a Pt-Au alloy, a Pt-Rh-Au alloy or a Pt-Rh-Pd-Au alloy, and the material of the hollow tube is a Pt-Au alloy, a Pt-Rh-Au alloy, a Pt-Rh alloy, a Pt-Rh-Pd alloy platinum the grains of which are stabilized by an oxide or a platinum alloy the grains of which are stabilized by an oxide. A process of preparing a bushing base plate for spinning glass fibers which comprises forming circular or irregular apertures (12, 22, 32, 42, 52, 62, 72) through a bushing base raw plate (11, 21, 31, 41, 51, 61, 71), press fitting a hollow tube (13, 23, 33, 43, 53, 63, 73) of outer dimensions larger than the dimensions of the apertures into each of the apertures or inserting in each of the apertures a hollow tube and expanding the hollow tube from the inside, and bonding the press-fitted or expanded hollow tube to the bushing base raw plate (11, 21, 31, 41, 51, 61, 71) over the full axial length of the aperture by thermal diffusion. The process of claim 11, characterized by forming each of said circular or irregular apertures (12, 32, 52) at the center of a corresponding swelling (14, 37) of the plate on the flow-out side thereof that is formed simultaneously with or before the formation of the said aperture. The process of claim 11, wherein the hollow tubes (13, 23, 33, 43, 53, 63, 73) and the bushing base raw plate (11, 21, 31, 41, 51, 61, 71) are subject to plastic deformation during said press fitting or expanding. The process of claim 11, wherein the material of the hollow tube (13, 23, 33, 43, 53, 63, 73) is different from that of the bushing base raw plate (11, 21, 31, 41, 51, 61, 71). The process of claim 11, wherein said apertures have a tapered or rounded portion on the glass flow-in side (d1, d6, d8, d10) of larger size than the size of the portion of the aperture on the glass flow-out side (d2, d7, d9, d11) and the hollow tube fitting into each aperture has a similarly variable cross section as the aperture into which it is fitted. The process of claim 15, wherein the aperture and the hollow tube have an angle (1-4) of tapering comprised between 0.01° and 120°. The process of claim 15, wherein the aperture and the hollow tube have two or more tapered portions with different angles (1-4) of tapering. The process of claim 17, wherein the angle (1-4) of at least one of the taperings is comprised between 0.01° and 120°. The process of preparing a bushing base plate according to claim 15, characterised by forming a swelling (14, 37), for reinforcing the hollow tube (13, 33, 53), about the periphery of the aperture (12, 32, 52) in the plane on the glass flow-out side of the bushing base raw plate (11, 31, 51). The process of claim 11, wherein after said bonding by thermal diffusion the shape of the flow-out aperture is molded to a desired shape and desired dimensions by plastic deformation. The process of claim 20, wherein said bonding by thermal diffusion and said molding are repeated several times. The process of claim 15, wherein after the hollow tube (13, 23, 33, 43, 53, 63, 73) is bonded to the bushing base raw plate (11, 21, 31, 41, 51, 61, 71) inside the aperture (12, 22, 32, 42, 52, 62, 72) by thermal diffusion, the bonding boundary on the glass flow-in side and/or on the glass flow-out side having said tapered or rounded shape is subjected to a plastic molding. The process of claim 11, wherein the thermal diffusion is conducted at a temperature comprised between 500°C and a temperature 20°C lower than the melting point of the material.

Inventors: HONMA TOSHIO, MITANI MAKOTO, SHIMIZU SUSUMU, SUGURO KATSUMI, HONMA, TOSHIO, MITANI, MAKOTO, SHIMIZU, SUSUMU, SUGURO, KATSUMI, HONMA, TOSHIO, C/O TANAKA KIKINZOKU KOGYO, MITANI, MAKOTO, C/O TANAKA KIKINZOKU KOGYO, SHIMIZU, SUSUMU, C/O TANAKA KIKINZOKU KOGYO, SUGURO, KATSUMI, C/O TANAKA KIKINZOKU KOGYO
Applicants: TANAKA PRECIOUS METAL IND, TANAKA KIKINZOKU KOGYO K.K.
Application year: 1995
Main classification: C03B37
IPC codes: C03B37, D01D4, B23K20, B23P11