JP2014109061A - Bearing for molten metal plating bath - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dynamic pressure type bearing which can suppress direct contact of a shank with a bearing in a sliding boundary surface without arrangement of a pump or a supply mechanism having piping, like static pressure type bearings.SOLUTION: A bearing for a dynamic pressure type molten metal plating bath supports a nearly columnar shape shank to be immersed in a molten metal plating bath in a freely rotatable way and comprises a nearly arc-shaped inner surface arranged so as to face the outer peripheral surface of the shank, a groove formed in the inner surface and a supply passage having a first opening part opened to the inner surface and a second opening part which molten metal of the molten metal plating bath flows in. The first opening is arranged on the near side with respect to the groove in the rotational direction of the shank.

Description

  The present invention relates to a bearing for a molten metal plating bath incorporated in a molten metal plating apparatus.

  The bearing for a molten metal plating bath is used by being incorporated in a molten metal plating apparatus 20 schematically shown in FIGS. The molten metal plating apparatus 20 is immersed in a plating tank 22 in which a molten metal plating bath (hereinafter may be simply referred to as a “plating bath”) 21 and a surface layer portion of the plating bath 21. Snout 23 for preventing oxidation of steel sheet W introduced into the inside, sink roll 27 arranged in plating bath 21, and a pair of support rolls located above sink roll 27 in plating bath 21 28 and a gas wiping nozzle 26 positioned slightly above the surface of the plating bath 21. No external driving force is applied to the sink roll 27 itself, and the sink roll 27 is driven counterclockwise by a frictional force caused by contact with the traveling steel plate W. The support roll 28 is typically a drive roll connected to an external motor (not shown). The support roll 28 may be a non-driving type in which no external driving force is applied. As shown in FIG. 2, the sink roll 27 and the pair of support rolls 28 are respectively provided with shaft portions 27b and 28b by bearings 90 for a molten metal plating bath attached to the frames 24 and 25 via the fixing member 10 and the like. It is rotatably supported and is always immersed in the plating bath 21 as a unit.

  The steel sheet W enters the plating bath 21 from the oblique direction through the snout 23, and the traveling direction thereof is changed upward while contacting the body portion 27a of the sink roll 27. The steel plate W rising in the plating bath 21 is sandwiched between the body portions 28a of the pair of support rolls 28, so that the pass line is maintained and warpage and vibration are prevented. The gas wiping nozzle 26 sprays high-speed gas onto the steel sheet W coming out of the plating bath 21 and uniformly adjusts the thickness of the molten metal plating attached to the steel sheet W by the gas pressure of the high-speed gas. In this way, a plated steel sheet W that has been subjected to hot metal plating is formed.

  Here, a bearing for a molten metal plating bath (hereinafter sometimes simply referred to as a bearing) is required to have a long life with little wear due to sliding with a shaft portion in order to produce a plated steel sheet at low cost. It is done. Further, in order to prevent the occurrence of surface flaws due to slip and to ensure the surface quality of the plated steel sheet, the bearings are provided on the outer peripheral surface of a sink roll and a support roll (hereinafter, both may be collectively referred to as a roll). It is required that the roll rotates in a stable state so that the traveling speed of the steel sheet traveling while being in contact with the rotation of the roll is always synchronized.

  An example of a bearing corresponding to such a request is disclosed in Patent Document 1 below. Patent Document 1 discloses a “bearing structure of a roll in a molten metal plating bath of an apparatus for continuously plating a steel strip by immersing it in a molten metal, in the axial center of both sliding load surfaces of the bearing. In a bearing structure in which a groove is provided in the part, a groove (hereinafter referred to as a central groove) having a bent part having an angle opened in the rotation direction of the rotating shaft or the sliding direction of the bearing and closed at both ends is slid. A plurality of rows are attached in the direction ", the bearing is disclosed.

  According to the bearing of Patent Document 1 having such a central groove (so-called herringbone groove), a plating bath is supplied to the bent portion as the rotating shaft rotates, and as a result, the positive pressure generated in the bent portion causes the shaft portion and the bearing to move. The direct contact between the two at the sliding interface is suppressed, wear of the bearing and shaft portion is reduced, and a stable rotating state of the roll can be obtained. However, the plating bath functioning as the lubricating liquid is not sufficiently supplied to the bent portion, and the rotating shaft and the bearing may be in direct contact at the sliding interface. With respect to the bearing of Patent Document 1 which is this dynamic pressure type, a bearing in which direct contact between the bearing and the shaft portion is suppressed is desired from the viewpoint of lower wear of the bearing and rotation stabilization of the roll. An example of a bearing is disclosed in Patent Document 2 below.

  The bearing disclosed in Patent Document 2 is “in a bearing that supports a roll shaft in a bath of a continuous hot dip galvanizing apparatus, and is formed into an arc shape or an annular shape along the outer peripheral shape of the roll shaft, A liquid ejection hole is formed on the inner side facing the shaft, and is disposed at least on the outer periphery of the roll shaft on the side receiving the force from the roll shaft, and is connected to the bush via a pipe, and the bush is made of zinc A bearing that includes a pump that pumps a solution of the plating bath composition and supports the roll with the liquid ejected from the liquid ejection hole. Such a bearing of Patent Document 2 has a hydrostatic structure that supports the shaft portion while being floated by the hydraulic pressure of the plating bath pumped from the pump, and direct contact between the bearing and the shaft portion is suppressed, and the bearing is low. The wear and the rotation of the roll can be stabilized. However, since the hydrostatic bearing disclosed in Patent Document 2 supplies a plating bath at a predetermined hydraulic pressure, a supply mechanism such as a pump and piping is required, and the molten metal plating apparatus is expensive. Furthermore, members such as pipes immersed in the plating bath need to be periodically repaired and replaced, and the running cost increases. Since there is a problem of increasing the cost of the plated steel sheet in this way, the actual situation is that the bearing of Patent Document 2 is not embodied in industrial production.

JP 2009-120890 A Japanese Patent Laid-Open No. 3-115552

  The present invention has been made in view of the above-described problems of the prior art, and does not include a supply mechanism having a pump, piping, or the like unlike the static pressure type bearing exemplified in Patent Document 2, and is disclosed in Patent Document 1. It aims at providing the bearing which can suppress the direct contact with the axial part and bearing at a sliding interface with respect to the bearing illustrated.

  One aspect of the present invention that achieves the above object is a molten metal plating bath bearing that rotatably supports a substantially cylindrical shaft immersed in a molten metal plating bath, and is opposed to the outer peripheral surface of the shaft. A substantially arc-shaped inner surface arranged in such a manner, a groove formed in the inner surface, a first opening opening in the inner surface, and a supply passage having a second opening into which a molten metal plating bath flows. The first opening is a bearing for a molten metal plating bath disposed on the front side of the groove in the rotation direction of the shaft portion.

  The first opening has an inclined surface that is inclined toward the front side at an intersecting angle of less than 90 ° in the rotation direction of the shaft portion with respect to a tangent in a cross section of the inner surface perpendicular to the center line of the inner surface. It is preferable.

  Furthermore, the supply passage preferably has a bent portion, and in addition, has a large-diameter hole portion disposed on one end side thereof and a small-diameter hole portion disposed on the other end side, and the first opening portion is It is desirable that the second opening is formed at one end of the large diameter portion and the other end of the small diameter portion.

  In addition, it is preferable that the first opening is arranged so that at least a part thereof is included in the groove in a direction along the center line of the inner surface. In this case, a plurality of the first openings may be arranged in a direction along the center line of the inner surface, or arranged so as to include the groove in a direction along the center line of the inner surface. More desirable.

  Since the present invention is configured as described above, the object of the present invention can be achieved.

It is a figure which shows schematic structure of the molten metal plating apparatus with which a bearing is integrated. It is a front view which shows a part of roll and bearing of FIG. 1 in a cross section. It is a front sectional view of the bearing of the first embodiment. It is AA sectional drawing of Fig.4 (a). It is OO sectional drawing of Fig.4 (a). FIG. 5 is a development view of a range of J in FIG. 4A when the F part in FIG. 4B is viewed from the G direction. It is a figure which shows the modification of Fig.4 (a). It is a figure which shows another modification of Fig.4 (a). It is an expanded sectional view near the supply passage of the bearing of a 2nd embodiment. It is the conceptual diagram which shows the expanded view of the inner surface in the B section of Fig.6 (a), and the distribution of the pressure in the said B section. It is a front sectional view of the bearing of the third embodiment. It is a front sectional view of the bearing of the fourth embodiment. It is the figure which looked at the K section of Drawing 8 (a) from the M direction.

  The present invention will be described below based on specific first to fourth embodiments with reference to the drawings.

[First Embodiment]
The configuration of the bearing 1 of the first aspect will be described with reference to FIGS. The structure of the molten metal plating apparatus in which the bearing 1 is incorporated is the same as that of FIGS. 1 and 2 described above except that the conventional bearing 90 is a bearing according to the present invention, and detailed description thereof is omitted. . Hereinafter, a bearing that supports the sink roll will be described as an example, but the bearing can also be applied to a support roll. Moreover, each component of the bearing of each embodiment is not limited only to the embodiment, and can be appropriately combined as long as the effects of the present invention are exhibited. Furthermore, since the right bearing 1 and the left bearing 1 shown in FIG. 2 are the same in each embodiment, the configuration of the right bearing 1 will be described, and the description of the left bearing 1 will be omitted.

  The bearing 1 of the first aspect is a dynamic pressure type bearing 1 that rotatably supports a substantially cylindrical shaft portion 27b of a sink roll 27 immersed in a molten metal plating bath. As shown in FIG. 3, the bearing 1 has a substantially arc-shaped inner surface 1d disposed so as to face the outer peripheral surface of the shaft portion 27b, and a groove 1e is formed in the inner surface 1d. In the dynamic pressure type bearing 1, the groove 1e in which positive pressure is generated as described below is a sliding interface 1m on the inner surface 1d of the bearing 1, as shown in FIGS. 3 (b) and 3 (c). It is formed so that at least a part is included in a region X (hereinafter, also referred to as a contact region) X that the shaft portion 27b contacts. The bearing 1 is provided with a supply passage 1b having a first opening 1g opened on the inner surface 1d and a second opening 1h into which a molten metal plating bath flows. The first opening 1g of the supply passage 1b is disposed on the front side of the groove 1e in the rotation direction of the shaft portion 27b (hereinafter sometimes simply referred to as the rotation direction).

  According to this bearing 1, the following effects can be obtained. That is, as shown in FIG. 3B, the plating bath is dragged by the viscosity of the shaft portion 27b as the shaft portion 27b rotates, and the outer peripheral surface of the shaft portion 27b and the bearing are present in front of the sliding interface 1m in the rotation direction. 1 flows in the gap 1o with the inner surface 1d (hereinafter, the flow of the plating bath in the gap 1o may be referred to as the main flow). A plating bath flowing in the gap 1o flows into the groove 1e formed on the inner surface 1d of the bearing 1 to generate a positive pressure, and the positive portion supports the shaft portion 27b while floating at the sliding interface 1m. Is done. Here, since the first opening 1g of the bearing 1 according to this aspect is disposed on the near side of the groove 1e in the rotation direction, the first opening 1g is dragged by the main flow of the plating bath flowing in the gap 1o. The plating bath flows in from the opening 1g of 1 and joins the main stream, and is supplied to the groove 1e. In this way, by flowing from the first opening 1g and joining the main flow, more plating bath is supplied to the groove 1e, and positive pressure is stably generated in the groove 1e. As a result, the shaft portion 27b is stably supported by the sliding interface 1m, and direct contact between the shaft portion 27b and the bearing 1 at the sliding interface 1m is suppressed. Furthermore, the bearing 1 is immersed in the plating bath, and the plating bath existing outside the bearing 1 continuously flows into the supply passage 1b through the second opening 1h. Therefore, the supply of the plating bath from the first opening 1g to the gap 1o can be continued without providing a special supply mechanism, and the positive pressure generated in the groove 1e can be maintained during operation.

  As described above, according to the bearing 1 according to the present invention, more plating bath is continuously supplied to the groove 1e through the first opening 1g arranged as described above, and thus the stable generated in the groove 1e. Since the positive pressure is maintained during operation, direct contact between the shaft portion 27b and the bearing 1 is suppressed. As a result, the low wear of the bearing 1 and the rotational stability of the sink roll 27 are realized, so that a plated steel plate with high surface quality can be produced at low cost. Hereinafter, the specific structure of the bearing 1 of the 1st aspect which is a preferable aspect is demonstrated in detail.

  As shown in FIG. 3, the bearing 1 of the first aspect having a substantially rectangular cross section perpendicular to the center line I has a substantially U-shaped cross section along the center line I, and the center line I of the inner surface 1d. The hollow portion 1n is formed in the central portion when viewed from a direction along the direction (hereinafter, sometimes referred to as a center line direction). The hollow portion 1n has a substantially cylindrical inner surface 1d formed with a predetermined radius around the center line I, and the inner surface 1d is relative to the outer peripheral surface of the shaft portion 27b inserted into the hollow portion 1n. It is arranged in the state to do. The shaft portion 27b having a smaller diameter than the hollow portion 1n of the bearing 1 is in the contact region X due to the tension applied to the steel plate during operation, and the outer peripheral surface thereof is in contact with the inner surface 1d. The sliding interface 1m is configured. In order to support the shaft portion 27b at the sliding interface 1m, the groove 1e is arranged so that at least a part thereof is included in the contact region X on the inner surface 1d of the bearing 1.

  The groove 1e of the present embodiment formed in parallel with the rotation direction is a groove whose cross-sectional shape in a direction orthogonal to the center line I (hereinafter sometimes referred to as a radial direction) has a substantially crescent shape. That is, the groove (hereinafter sometimes referred to as a crescent groove) 1e formed in a finite length in the circumferential direction so as to occupy a part of the surface of the sliding surface 1d has a substantially arc-shaped bottom surface. It has a deepest center in the rotation direction and gradually becomes shallower toward both ends. According to the crescent groove 1e having such a cross-sectional shape, the plating bath flows in along with the rotation of the shaft portion 27b, so that the crescent groove 1e of the crescent groove 1e in the rotation direction as shown in the diagram Q1 in FIG. A positive pressure peak is shown at the far end. The end on the back side of the crescent groove 1e is disposed so as to be included in the contact region X (sliding interface 1m), thereby preventing direct contact between the shaft portion 27b and the bearing 1.

  Although the cross-sectional shape orthogonal to the center line I of the crescent moon groove 1e of the present embodiment is symmetric with respect to the center in the rotation direction, it may be asymmetric. Further, the width in the center line direction of the groove 1e may be the same or may be changed. Further, a plurality of crescent grooves 1e may be provided at equal intervals or unequal intervals in the center line direction, and a plurality of grooves 1e may be provided at equal angles or unequal angles in the circumferential direction. That is, the groove formed on the inner surface of the bearing may be in a form in which a positive pressure is generated at least in part when the plating bath flows in, and the portion where the positive pressure is generated is disposed in the sliding interface (contact region). By doing so, the shaft portion can be supported.

  Further, if the plating bath flowing from the supply passage 1b is supplied to the groove 1e, the positional relationship between the first opening 1g of the supply passage 1b and the groove 1e is not particularly limited, but as shown in FIG. In addition, it is desirable that the first opening 1g is arranged so that at least a part thereof is included in the groove 1e in the center line direction. Furthermore, the supply passage 1b of the present embodiment is a through hole having a substantially circular cross-sectional shape, but the cross-sectional shape is not limited to a substantially circular shape, and may be, for example, a substantially rectangular shape shown in FIG. It may be a substantially triangular shape or a substantially elliptical shape. Further, the supply passage 1b of the present embodiment has a straight tubular shape with no change in cross-sectional shape, and the lower (one) side thereof is a first opening 1g and the upper (other) side is a second opening 1h. However, the cross-sectional shape in the radial direction may be changed, or may be a partially bent shape.

  In addition, as long as the above basic configuration is satisfied, even with a single supply passage, the effects of the present invention can be achieved. However, as shown in FIG. It is preferable to arrange a plurality of 8g because more plating bath can be supplied to the crescent groove 1e. From the same point of view, the first opening 3g shown in FIG. 4C may have a substantially elongated hole shape and be disposed so as to include the crescent groove 1e in the center line direction. Good.

  The further preferable component with which the bearing 1 of this aspect is provided is demonstrated below. As shown in FIG. 3 (a), the bearing 1 of this embodiment has a bearing end portion at the right end in order to receive the end face of the shaft portion 27b that moves in the horizontal direction during operation and hold the position of the horizontal roll. 1o is arranged. In addition, you may extend the hollow part 1n to the left end, without providing this bearing end part 1o. Further, when the bearing end 1o is provided on the bearing 1 as described above, in order to prevent foreign matter in the plating bath called dross from staying inside the bearing 1, the bearing end is moved from the left end of the hollow portion 1n. A liquid reservoir portion 1c having a larger inner diameter than the hollow portion 1n and an opening portion 1f formed so as to penetrate the bearing end portion 1o in the center line direction are provided in the region up to the portion 1o. It is preferable to keep it. With this configuration, even when the shaft portion 27b is inserted into the bearing 1, the plating bath can freely enter and exit the liquid reservoir portion 1c and circulate through the hollow portion 1n.

[Second Embodiment]
The bearing 2 of 2nd Embodiment which concerns on this invention is demonstrated with reference to FIG. In FIG. 5, the same components as those of the bearing of the first aspect are denoted by the same reference numerals, and detailed description thereof is omitted (the same applies to the bearings of other embodiments described below). .

  As shown in FIG. 5A, which is an enlarged sectional view of the periphery of the supply passage 2 b of the bearing 2 of the second aspect, the bearing 2 which is a preferable aspect has a first opening 1 g having an inner surface 1 d of the bearing 1. It differs in that it has an inclined surface 2k that is inclined to the near side at a crossing angle P of less than 90 °, preferably 10 to 60 ° in the rotational direction with respect to a tangent line E in the cross section of the inner surface 1d perpendicular to the center line I. ing. According to the bearing 2, by providing the inclined surface 2k in the first opening 1g, as described below, more plating bath can be supplied to the crescent groove 1e with respect to the bearing of the first mode. It becomes possible.

  That is, as shown in FIG. 5 (b), which is a development view (upper view) of the range of the symbol B of the inner surface 1d in FIG. 5 (a) and a conceptual diagram (lower view) of the pressure distribution in the range. Along with the rotation of the portion 27b, the plating bath flows through a gap 1o between the outer peripheral surface of the shaft portion 27b and the inner surface 1d of the bearing 1 that exists in front of the sliding interface 1m in the rotation direction. A plating bath flowing in the gap 1o flows into the crescent groove 1e formed on the inner surface 1d of the bearing 1 to generate a positive pressure shown in a diagram Q1, and the shaft portion at the sliding interface 1m is generated by the positive pressure. 27b is supported while rising.

  Here, the 1st opening part 1g of the bearing 2 which concerns on a 2nd aspect has the inclined surface 2k arrange | positioned as mentioned above. For this reason, the main flow of the plating bath flowing through the gap 1o collides with the inclined surface 2k and the flow velocity is reduced, and as shown by a line Q2 in FIG. 5B, a negative pressure is generated in the region of the inclined surface 1k. Will occur. Since the negative pressure causes the plating bath in the supply passage 2b to flow into the gap 1o and merge with the main flow, more plating baths are formed in a crescent groove in a manner superimposed on the effects described in the bearing of the first aspect. 1e. Therefore, a positive pressure is more stably generated in the crescent groove 1e, the shaft portion 27b is more stably supported by the sliding interface 1m, and direct contact between both at the sliding interface 1m between the shaft portion 27b and the bearing 1 is caused. It is suppressed. In addition, the aspect of the continuous supply to the supply passage 2b of the plating bath through the second opening 1h is the same as that of the bearing 1 of the first aspect, and the positive pressure generated in the groove 1e is maintained during operation. Can do.

  The supply passage 2b of this embodiment is also formed in a straight tube shape, and is arranged so that the entire supply passage 2b is inclined with respect to a tangent line E in the cross section of the inner surface 1d perpendicular to the center line I of the inner surface 1d of the bearing 1. Thus, the inclined surface 2k is configured. However, for example, the inclined surface 2k may be formed by arranging only the first opening 1g to be inclined at a predetermined inclination angle. That is, the inclined surface is a surface on which the main flow of the plating bath flowing in the gap 1o collides, as described in the bearing of the third aspect below, and the inner surface 1d perpendicular to the center line I of the inner surface 1d of the bearing 1. The surface may be a surface of less than 90 ° with respect to the tangent line E in the section. Moreover, the cross-sectional shape in the radial direction of the supply passage 2b may be changed, or a part thereof may be bent. The specific aspect will be described in detail in the bearing of the third embodiment below.

[Third Embodiment]
A bearing 5 according to a third embodiment of the present invention will be described with reference to FIG. The bearing 5 which is a further preferred embodiment of the bearing of the second aspect is (1) a combination structure of the bearing portion 5a and the holding portion 6, and (2) the supply passage 5b has a large diameter hole portion 5j and a small diameter hole portion 5i. And is different from the bearing of the second mode in that it further includes a bent portion 5L. Hereinafter, the differences (1) and (2) will be described.

  As shown in FIG. 6, the bearing 5 includes a substantially U-shaped holding part 6 having a semicircular inner surface 6 a formed in a cross section perpendicular to the center line I and having a recess having an open bottom surface, and a holding part 6. The bearing portion 5a has an outer peripheral surface that is substantially the same diameter as the inner surface 6a, and is fitted into the bottom surface of the holding portion 6 so that the outer peripheral surface is in close contact with the inner surface 6a of the holding portion 6 and the bottom surface of the holding portion 6. And a fixing member 6d for fixing the bearing portion 5a. And the crescent groove | channel 1e is formed in the inner surface 1d of the bearing part 5a so that at least one part may be contained in the contact area | region X (sliding interface 1m) similarly to the said 2nd aspect. In this way, the bearing 6 having a combined structure of the bearing portion 5a and the holding portion 6 includes, for example, the bearing portion 5a made of ceramics having excellent corrosion resistance and wear resistance against a plating bath as described below. This is a preferred configuration when 6 is made of an inexpensive metal.

  Here, the supply passage 5b of the third aspect is similar to the supply passage of the second aspect in the cross section of the inner surface 1d in which the first opening 1g is orthogonal to the center line I of the inner surface 1d of the bearing 1. With respect to the tangent line E, it has the inclined surface 2k inclined to the near side at an intersection angle P of less than 90 °. However, the supply passage 5b is different in that it has a large-diameter hole 5j disposed on the lower (one) side and a small-diameter hole 5i disposed on the upper (other) side. A first opening 1g is formed at the lower end (one end) of the large-diameter hole 5j, and a second opening 1h is formed at the upper end (the other end) of the small-diameter hole 5i. Here, in the supply passage 5b of the present aspect, the large-diameter hole portion 5j in which the first opening portion 1g that opens to the inner surface 1d is formed at the lower end is perpendicular to the center line I of the inner surface 1d of the bearing 1. With respect to the tangent line E in the cross section of the inner surface 1d, it is arranged so as to be inclined toward the near side at an intersecting angle of less than 90 °, thereby forming the inclined surface 2k. Moreover, as shown in the drawing, the large-diameter hole portion 5j is formed in the bearing portion 5a, and the small-diameter hole portion 5i is formed in the holding portion 6, but the arrangement of both is not limited to this, and the large-diameter hole portion The part 5j may be extended to the holding part 6 side, and the small diameter hole part 5i may be extended to the bearing part 5a side.

  Thus, according to the supply passage 5b having the large-diameter hole 5j and the small-diameter hole 5i, the small-diameter hole 5i having the second opening 1h into which the plating bath flows from the outside is larger than the large-diameter hole 5j. The inner diameter is small and the pipe resistance is large. By arranging the small-diameter hole portion 5j having a large pipe resistance, it is effective that the main flow of the plating bath flowing in the gap 1o flows into the large-diameter hole portion 5j, that is, the supply passage 5b through the first opening 1g. To be suppressed. As a result, the inflow of the plating bath from the first opening 1g to the gap 1o becomes smoother, and more plating bath is supplied to the groove crescent moon 1e. Furthermore, in order to prevent the main flow of the plating bath flowing in the gap 1o from flowing into the large-diameter hole 5j (supply passage 5b), it is preferable to provide a bent portion 5L in the supply passage 5b. In addition, although the bending part 5L of this aspect is formed in one place between the large diameter hole part 5j and the small diameter hole part 5i arrange | positioned with respect to the said large diameter hole part 5j, the bending part 5L is It suffices to provide any part of the supply passage 5b, or a plurality of parts may be provided.

[Fourth Embodiment]
FIG. 7B is a developed view of the bearing 7 of the fourth embodiment according to the present invention as viewed from the reference M in the range of the reference K in FIG. 7A and FIG. Will be described with reference to FIG.

  As shown in FIG. 7, the bearing 7 according to the fourth mode is different from the bearing 2 according to the second mode in that the groove 7e formed on the inner surface 1d has a so-called herringbone shape. That is, the groove 7e of this embodiment has a first groove 7j, a second groove 7k, and a connecting recess 7L that connects the inner ends (one end portions) of the first groove 7j and the second groove 7k. In the rotation direction of the shaft portion, the outer end portions (the other end portions) of each of the first groove 1m and the second groove 1n are both arranged behind the connecting recess 1L (hereinafter referred to as “rear end portions”). This form of groove is sometimes referred to as a herringbone groove.) The two herringbone grooves 7e (7e-1, 7e-2) are arranged in the rotational direction, and at least a part of the herringbone groove 7e is formed in the contact region X (sliding interface 1m). . Note that the number of herringbone grooves 7e is not limited to two as illustrated, and may be one or three or more. In addition, the shapes and dimensions of the plurality of herringbone grooves 7e do not have to be the same, and may be different shapes and dimensions.

  According to the herringbone-shaped groove 7e, the outer end portions of the first groove 7j and the second groove 7k are arranged behind the connecting recess 7L in the rotation direction of the shaft portion. The plating bath that flows in the rotation direction with the rotation of the portion flows into the first groove 7j and the second groove 7k from the outer end portion, and then merges at the connecting recess 7L, and flows out from a narrow gap at the sliding interface. To do. Then, the flow rate of the plating bath rapidly changes in the connecting recess 7L, and a positive pressure is generated in the connecting recess 7L. As a result, the shaft portion is supported while floating at the sliding interface 1m due to the positive pressure generated in the connecting recess 7L of the herringbone grooves 7e-1 and 7e-2 disposed at the sliding interface 1m.

  And also in the bearing 7 of this aspect, the supply path 2b similar to the bearing of the said 2nd aspect is arrange | positioned. Specifically, in order to supply plating baths to the herringbone grooves 7e-1 and 7e-2 arranged so as to be included in the sliding interface 1m, an inclined surface is provided on the inner surface 1d arranged in front of them in the rotation direction. The first opening 1g having 2k is arranged to open. As a result, like the bearing of the second aspect, more plating bath is supplied to the herringbone grooves 7e-1 and 2, and positive pressure is more stably generated in the herringbone grooves 7e-1 and 2, and the shaft portion Is more stably supported at the sliding interface 1m, and direct contact between the shaft portion 27b and the bearing 1 at the sliding interface 1m is suppressed. In the case of the herringbone groove 7e, it is desirable to arrange the first opening 1g to open at substantially the same position as the connecting recess 7L in which a positive pressure is generated, as indicated by the symbol N in the center line direction.

  The bearing or bearing portion is preferably made of ceramics from the viewpoint of corrosion resistance and wear resistance. The ceramics include alumina, zirconia, silica and other oxide ceramics, zirconium boride, titanium boride, boron, depending on the thermal shock resistance and corrosion resistance required by the operating conditions of the bearings and other operating conditions. Boron fluoride and other boride ceramics, silicon carbide / boron carbide and other carbide ceramics, or inorganic materials such as carbon may be used. And since a bearing etc. are rapidly heated and quenched at the time of immersion in a plating bath and taking out, they need to be excellent in thermal shock resistance. Therefore, as the ceramics constituting the bearings, silicon nitride, aluminum nitride and other nitride ceramics with high thermal conductivity are preferable, and they have high resistance to erosion and wear against molten metal as a plating bath. Particularly preferred are silicon nitride ceramics containing sialon having excellent high-temperature strength.

  As a method for forming the groove and the supply passage in the bearing or the like, when the bearing or the like is made of metal, a known machining method such as cutting, electric discharge machining or the like can be applied. On the other hand, when a bearing or the like is made of a difficult-to-cut material ceramic, for example, a groove and a supply passage are formed in a molded body before sintering and then sintered, and the sintered bearing or the like is ground. A method of forming a groove and a supply passage by removing with a laser, shot blasting, or the like can be applied.

1 (2-7) Bearing 5a Bearing portion 1b (2b, 5b) Supply passage 1d Inner surface 1e (7e) Groove 1g First opening 1h Second opening 1m Sliding interface

Claims (7)

  A bearing for a molten metal plating bath that rotatably supports a substantially cylindrical shaft portion immersed in the molten metal plating bath, the inner surface having a substantially arc shape disposed to face the outer peripheral surface of the shaft portion, and A groove formed in the inner surface, a first opening opening in the inner surface, and a supply passage having a second opening through which a molten metal plating bath flows, wherein the first opening includes the shaft portion. A bearing for a molten metal plating bath disposed on the front side of the groove in the rotation direction.   The first opening has an inclined surface inclined toward the front side at an intersecting angle of less than 90 ° in a rotation direction of the shaft portion with respect to a tangent in a cross section of the inner surface perpendicular to the center line of the inner surface. 2. A bearing for a molten metal plating bath according to 1.   The bearing for a molten metal plating bath according to claim 1, wherein the supply passage has a bent portion.   The supply passage has a large-diameter hole portion disposed on one side thereof and a small-diameter hole portion disposed on the other side thereof, and the first opening portion is provided at one end of the large-diameter portion, The bearing for a molten metal plating bath according to any one of claims 1 to 3, wherein the opening is formed at the other end of the small diameter portion.   The bearing for a molten metal plating bath according to any one of claims 1 to 4, wherein the first opening is disposed so that at least a part thereof is included in the groove in a direction along a center line of the inner surface. .   The bearing for a molten metal plating bath according to any one of claims 1 to 5, wherein a plurality of the first openings are arranged in a direction along a center line of the inner surface.   The said 1st opening part is a bearing for molten metal plating baths in any one of the Claims 1 thru | or 6 arrange | positioned so that the said groove | channel may be included in the direction along the centerline of the said inner surface.

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