TITLE OF THE INVENTION Sliding nozzle plate and sliding nozzle device using the same TECHNICAL FIELD [0001] . { The present invention relates to a sliding nozzleplate (hereinafter referred to as "SN plate") for use in a sliding nozzle device (hereinafter referred to as "SN device") for adjusting an outflow amount of molten metal from a molten metal vessel, particularly, a SN plate comprising: a member defining*a partial region surrounding a through-hole serving as a flow passage for molten metal; and a SN plate body defining a remaining region, wherein the member is formed separately from the SN plate body, and fitted into and integrated with the SN plate body (this type of SN pl{e will hereinafter be referred to as "composite SN plate"), and a SN device using ...".| the SN plate. [0002] As used in this specification, the term "composite SN plate" encompasses not only a type in which the SN plate body is a recycled SN plate obtained by recycling a used SN plate, but also a type in which the SN plate body is an unused SN plate. , - !ABACKGROUND ART [0003] A SN device is widely used, for example, in a ladle and a tundish, because it has an advantage of being able to accurately control an outflow amount of molten metal. The SN device includes a two-plate type and a three-plate type. For example, the two-plate type SN device is equipped with a SN plate consisting of an upper plate and a lower plate, and configured to slidingly move the lower plate in an opening or closing direction to cause respective through-holes (nozzle holes) provided in the upper and lower plates to be aligned or misaligned rvith each other, thereby adjusting an outflow amount of molten metal. [0004] Such a SN plate used in the SN device is damaged due to molten metal during use. In -lKRC- I28US PCT/JP2o1U7789r particular, a.surface of the SN plate defining the through-hole for allowing molten metal to pass therethrough will be severely damaged. Such a damaged SN plate has to be replaced with a normal bne. In this case. from an economic standpoint, it is necessary to recycle the damaged or used SN plate, and some techniques for the recycling have already been proposed. [000s] For example, the following Patent Document 1 discloses a SN plate recycling method which comprises: diametrally enlarging a through-hole of a used SN plate; and attaching a tubular member having a ring=shaped flange to the diametrally-enlarged through-hole. [0006] FIG. 2 illustrates a SN device in which a SN plate recycled by the method disclosed in the Patent Document I is used in a lower plate. In FIG. 2, the reference numerals I, 2 and 3 indicate an upper plate, a recycled lower plate, and a tubular member having a ring-shaped flange 3a, respectively. [0007] However, when the recycled lower plate 2 having the tubular member 3 attached thereto as illustrated in'FIG 2 was used in an actual casting operation, a problem of displacement of the tubular member 3 used for recycling, and a problem of molten metal penetration into a joint 4 between the tubuiar member 3 and a SN plate body (i.e., a plate body of the recycled lower plate 2), occurred. [0008] The problems of the displacement of the tubular member 3 and the molten metal penetration into the.joint 4 occur in not only the recycled lower plate2, but also any other type of composite SN plate obtainable by attaching a tubular member to a SN plate body. LIST OF PRIOR ART DOCUMENTS [PATENT DOCUMENTS] [000e1 Patent Document l: JP 27788698 .-LKRC- I28US PCT/JP2o1 rl7789r SUMMARY OF THE TNVENTION ITECHNICAL PROBLEMI [0010] - In a composite SN plate obtainable by attaching a tubular member to a SN plate body, it is an object of the present invention to prevent displacement of the tubular member, and molten metal penetration into a joint between the tubular member and the SN plate body. [SOLUTION TO THE TECHNICAL PROBLEM] [00i 1] i According'to one aspect of the present invention, there is provided a SN plate for use in a sliding nozzle device for adjusting an outflow amount of molten metal from a molten metal vessel. The SN plate comprises: a tubular member having a flange and defining a partial region surrounding a--through-hole serving as a flow passage for molten metal; and a SN plate body defining a remaining region, wherein the tubular member is formed separately from the SN plate body and attached to and integrated with the SN plate body via a bonding material provided at . .-:l least bbtween an outer peripheral surface of a non-flange portion of the tubular member and a bore surface of the SN plate body, and wherein the SN plate satisfies the following conditional formulas (l) and (2): qB5eI-5 ---(1) 30' [0018] In the above conditional formula (3), qD is an inner diameter (mm) of the tubular member, which has a dimension equal to an inner diameter of a through-hole (nozzle hole) of the used SN plate. In an operation of recycling a used sN plate, a though-hole of the used SN plate is enlarged by boring so as to allow the tubular member to be attached thereto. The right side (( oc) .J EEttB*a*' KRC-128US PCT/JP20l r/77891 t003el In all of the inventive samples I to 5 illustrated in Table 1 each satisfying both the cond"itional formulas (l) and (2), no abnormality was observed during use' In contract' in the comparative sample I failing to satisfy the conditional formula (l), displacement of a tubular member occurred during use. In the comparative sample 2 faibng to satisfy the conditional formula (2), molten metal penetration into a joint occurred during use. [0040] (Example B) . lrr Example B, in a SN plate where a recycled SN plate obtained by recycling a used SN -plate is used as a SN plate body, an influence of a boring width of a through-hole (nozzle hole) pf the used SN plate on a recyclability rate of used SN plates was analyzed' [0041] The recyclability rate was evaluated in the following manner' A through-hole (nozzle hole)-of a used SN plate was diametrally enlarged by means of boring' In a bore surface of the diametrally-enlarged through-hole, a region in an angular range of 90 degree on a leading side of a sliding movement in an opening stroke direction (range indicated by A in FIG' 4) was observed' Then, a sample having no open crack was evaluated as "recyclable"' Specihcally' a crack having a gap sf 0.5 mm or more was determined to be an open crack' This is because' as long as a crack has a gap of less than about 0.5 mm, the molten metal penetration will never occur' even if molten steel contacts the crack. The above operation was performed for 100 used SN plates under the same boring conditions, and a rate of samples evaluated as "recyclable" was used as a recYclabilitY rate' 100+2) FlG.5illustratesarelationshipbetweenarecyclabilityrateand''qB(adiameterofa diametrally-enlarged through-hole) -