JP5134341B2 - Flange type pipe joint and steel pipe bulge forming device - Google Patents

Description

  The present invention relates to a flange-type pipe joint that can easily and reliably connect a pair of stainless steel pipes at a construction site and a steel pipe bulge forming apparatus.

  Thin steel pipes made of stainless steel are used for cold and hot water pipes such as water supply pipes and buildings. For example, a steel pipe and a pipe joint are connected using a connection structure shown in Patent Document 1 or Patent Document 2. Patent document 1 expands the pipe end of a thin-walled stainless steel pipe to form a chevron projection having two inclined surfaces, and closely contacts one inclined surface of the chevron protuberance on the inner periphery of the end of the pipe joint. The connection mechanism of the steel pipe and joint which formed the 1st notch part which consists of the taper part and packing fitting part which do, and formed the 2nd notch part closely_contact | adhered to the other inclined surface of a mountain-shaped projection part inside a nut is shown. In this connection mechanism, when the female thread part of the nut and the male thread part formed on the outer peripheral end of the joint body are screwed together, the packing inserted into the gasket fitting part is inclined to one of the chevron protrusions of the thin stainless steel pipe. It closely adheres to the joint contact surface between the surface and the second notch portion inside the nut and the female screw portion. The connection mechanism of Patent Document 1 is easy for steel pipes with an outer diameter of up to about 60.5 mm (JIS G 3448 called 60 Su) by rotating the nut with a relatively small force on the male thread at the outer peripheral end of the joint body. It has good workability and is widely used for hot water supply and water supply piping.

  The connection structure of Patent Document 2 includes a thin stainless steel pipe, a joint body, a clamping part, a clamping ring, packing, gasket packing, bolts and nuts. A bulging part having two inclined surfaces is formed at the pipe end of a thin steel pipe made of stainless steel, and a fitting part for placing a sandwich ring and packing at the outer peripheral end on the joint body side and the flange part and the inner peripheral end part The sandwiching portion having an inner diameter portion forms an inclined pressing surface that presses one inclined surface of the steel pipe, and sandwiches the bulging portion of the steel pipe together with a packing that is disposed in the fitting portion and closely contacts the other inclined surface of the steel pipe. . The clamping ring that is arranged at the inner peripheral end of the clamping part and presses the packing against the inclined surface of the steel pipe has a flange on the joint body side, and forms a joint surface with the coupling body together with the clamping part. Adhere gasket packing. Bolts are passed through the through holes of the flange portions formed on the outer peripheral end, and the nut is tightened to fix the joint body and the clamping portion. The connection structure of Patent Document 2 can be constructed using bolts, nuts, and tools that are smaller and lighter than the fixing method of Patent Document 1 in which a nut larger in diameter than the connection pipe is fastened to the end of the joint body. In addition to being able to be easily connected, there is no co-rotation phenomenon in which other pipe joints that have already been installed are rotated in the removing direction and relaxed when tightening the bolts.

  The ridge-shaped bulged portion having two inclined surfaces of the steel pipe to be connected is formed by using, for example, a pipe expanding device shown in Patent Document 1 or Patent Document 3. As shown in Patent Literature 1 and Patent Literature 3, a tube expansion head, a shaft (guide rod) inserted through the tube expansion head, a rubber receiving portion fitted on the shaft, a tube expansion rubber and a rubber presser, and the tip of the shaft A pipe that attaches a connection pipe to a pipe expansion device whose main component is a locking portion fixed to the pipe, fixes a clamping member (nut) to the pipe expansion head, and pulls the shaft in a predetermined direction and inserts it inside the connection pipe The rubber is expanded in the outer peripheral direction, and the pipe end portion of the connecting pipe is expanded to the same shape as the circumferential groove having a cross-sectional shape formed by the inclined surface of the inner periphery of the tube expansion head and the clamping member (nut).

Reality No. 2-337015 Japanese Patent No. 3433248 Japanese Patent Publication No. 64-137

  However, the connection mechanism disclosed in Patent Document 1 is relatively easy to attach a nut to the male thread formed on the outer peripheral end of the joint body up to a steel pipe outer diameter of about 60.5 mm (JIS G 3448, called 60 Su). Although it can be screwed and fixed, the workability is generally good. However, when the outer diameter of the steel pipe is 76.3 mm (JIS G 3448, called 75 Su) or more, the nut screwed to the male screw part and the tool for tightening the nut increase in size. By increasing the weight of the joint itself, there is a drawback that the workability is greatly lowered and the handling becomes difficult. In addition, the friction resistance between the joint body and the threaded portion of the nut increases, making installation more difficult, and tightening of the nut becomes insufficient, resulting in a decrease in the sealing surface pressure between the packing and the connecting pipe. There was a problem of water stoppage performance degradation. Furthermore, the conventional connection structure in which the nut is directly screwed onto the outer peripheral end of the joint body, when used in hot water supply or cold / hot water piping, the fastening force between the joint body and the nut over time due to repeated thermal expansion and contraction. There was a possibility of leakage due to a decrease in the sealing surface pressure. Further, there has been a problem that a joint rotation phenomenon in which the connecting pipe rotates in synchronism with the rotation of the nut, and the pipe joint at the other end, which has already been completed, is rotated in the removing direction to be relaxed cannot be avoided.

  The connection structure according to Patent Document 2 can solve some of the problems of Patent Document 1, but the joint body is connected to the packing disposed between the inner periphery of the clamping part and the bulging part formed at the end of the connection pipe. There is no function of sealing between the flange portion and the flange portion of the sandwiching portion, and it is necessary to seal by separately sandwiching gasket packing between the flange portions. In such a connection structure using gasket packing, it is necessary to fasten the flange part of the joint body and the flange part of the clamping part with a large number of bolts to obtain a predetermined sealing surface pressure. There is a problem that the force tends to be uneven, and it is necessary to strictly control the tightening torque to maintain a predetermined pressure resistance performance and to spend a lot of labor to stabilize the construction quality. Moreover, since the number of parts also increases, there is a problem that the man-hours for management are increased and the workability is further reduced. Furthermore, the bolt inserted into the flange part may fall off during construction, and workability may be reduced.

  In the connection structure, the tube expansion device used for forming the bulging portion of the connection tube end needs to provide a bolt portion on the tube expansion head side that matches the bolt hole pitch of the holding flange portion. As the length increases, the size of the pipe expansion device inevitably increases, and the weight also increases. Therefore, there is a problem that transportation becomes difficult and mobility of field work is lost.

  In view of the above problems, the object of the present invention is to connect thin stainless steel pipes, particularly thin stainless steel pipes having an outer diameter of 76.3 mm (JIS G 3448, 75 Su) or more, and simply and reliably at the construction site. It is an object of the present invention to provide a lightweight flange-type pipe joint that can be connected. Moreover, the objective of this invention is providing a small bulging part formation apparatus.

The flange-type pipe joint of the present invention includes a through hole (10a), an annular groove (3) formed at an end of the through hole (10a), and a flange part (10b) formed with a bolt hole (10c). The main body (10), the packing (4) mounted in the annular groove (3) of the joint main body (10), the opening (11a) aligned with the through hole (10a) of the joint main body (10), the opening An inclined surface (13) formed in communication with (11a), a mounting ring (11) having a coaxial hole (11b) aligned with a bolt hole (10c) of the joint body (10), and a joint body (10) A bolt (7) inserted through the bolt hole (10c) of the flange portion (10b) and the coaxial hole (11b) of the mounting ring (11) and a nut (8) attached to the bolt (7) are provided. A bulge formed on the pipe end (1a) of a thin, stainless steel pipe (1) inserted into the through hole (10a) of the joint body (10) and the opening (11a) of the mounting ring (11). The pipe end side inclined surface (2a) of the portion (2) is in contact with the packing (4). Tighten the bolt (7) and nut (8) and connect the mounting surface (10g) of the flange (10b) of the joint body (10) and the mounting ring on the radially outer side of the top (2c) of the bulge (2). When the receiving surface (11d) of (11) comes into contact, the annular edge (3a) provided on the inner side in the axial direction from the annular groove (3) of the joint body (10) is the pipe end of the bulging portion (2). While contacting the rising portion of the side inclined surface (2a) or its adjacent portion, the inclined surface (13) of the mounting ring (11) is in contact with the other inclined surface (2b) of the bulging portion (2), The bulging portion (2) of the steel pipe (1) is sandwiched between the joint body (10) and the mounting ring (11). The mounting ring (11) includes a female thread portion (9) having an inner diameter larger than the maximum outer diameter of the bulging portion (2) of the steel pipe (1), and a vertical wall (12) adjacent to the female thread portion (9). . The inclined surface (13) is formed adjacent to the vertical wall (12), and the top portion (2c) of the bulging portion (2) is provided on the axially outer side from the annular groove (3) of the joint body (10). It is spaced radially inward from the hole end (10d) and the internal thread (9) of the mounting ring (11).

When the pair of flange-type pipe joints and the pipe end (1a) of the steel pipe (1) are connected in the final tightened state, the inclined surface (13) of the mounting ring (11) is connected to the other inclined surface ( 2b) is energized, and the annular edge (3a) provided on the axially inner side from the annular groove (3) of the joint body (10) is the rising part of the inclined surface (2a) on the pipe end side of the bulging part (2). Or, the inner surface of the joint body (10) forming the through hole (10a) and the outer surface of the steel pipe (1) are in contact with the portion of the pipe end side inclined surface (2a) adjacent to the rising portion, and the metals are in contact with each other. The first sealing structure is formed by the contact. Further, the packing (4) elastically contacts the tube end side inclined surface (2a) of the bulging portion (2) on the outer side in the axial direction of the annular edge (3a), and the second due to the elasticity of the packing (4). A sealing structure is formed. In this way, the fluid in the steel pipe (1) is made to flow in the steel pipe (1) by the double sealing structure of the first sealing structure by metal contact and the second sealing structure by elastic contact of the packing (4). It is possible to completely prevent leakage from between the outer surface and the joint body (10). Also, when tightening the joint body (10) and the mounting ring (11) by tightening the bolt (7) and nut (8), the mounting surface (10g) of the flange (10b) of the joint body (10) ) And the receiving surface (11d) of the mounting ring (11) are in contact with each other, so that it is easy without requiring strict control of the tightening torque as in the structure using the clamping ring and gasket packing shown in Patent Document 2. Can be constructed. Further, the mounting ring (11) of the flange-type pipe joint of the present invention has an opening (11a) aligned with the through hole (10a) of the joint body (10), and an inclination formed in communication with the opening (11a). Female screw having a surface (13), a coaxial hole (11b) aligned with the bolt hole (10c) of the joint body (10), and an inner diameter larger than the maximum outer diameter of the bulging portion (2) of the steel pipe (1) A vertical wall (12) adjacent to the portion (9), the female screw portion (9) and the inclined surface (13). When the female screw portion of the mounting ring (11) and (9) screwed into the bulged portion forming apparatus of a steel pipe, it is possible to attach the installation ring (11) to easily bulged portion forming apparatus without using a plurality of bolts . Further, the bulging portion (2) is formed in the space portion (30) formed by the hole end portion (10d) of the joint body (10), the vertical wall (12) of the mounting ring (11), and the female screw portion (9). Place the top (2c), and without applying external force to the top (2c) or the vicinity of the top (2c) of the bulging part (2), the bulging part (1) and the mounting ring (11) 2) can be clamped.

A steel pipe bulge portion forming apparatus according to the present invention includes a tube expansion head (16) fixed to a base (25) and a tube expansion head (16) coaxially movable forward and backward in the axial direction with respect to the tube expansion head (16). A tube guide (20) held by the tube, and an elastic member (18) and a spacer (19) disposed between the tube expansion head (16) and the tube guide (20). The pipe expansion head (16) includes a center hole (16a), a male screw portion (14) provided on the outer surface of the support end portion (16d), and a head inclined surface (15) provided on the inner surface of the support end portion (16d). The female screw portion (9) formed on the mounting ring (11) having the inclined surface (13) on the inner peripheral side is screwed into the male screw portion (14) of the tube expansion head (16). The length of the inclined surface (13) of the mounting ring (11) is shorter than the head inclined surface (15) of the tube expansion head (16).

  Inserted in the cylindrical space (24) formed between the opening (11a) of the mounting ring (11) and the pipe expansion head (16) and the pipe guide (20), the elastic member (18) and the spacer (19). The pipe end (1a) of the thin and stainless steel pipe (1) is in contact with the axial inner surface (16b) of the pipe expansion head (16). The pipe guide (20) is moved toward the pipe expansion head (16) to compress the elastic member (18) and expand its diameter outward in the radial direction, whereby the head inclined surface (15) of the pipe expansion head (16), The pipe end (1a) of the steel pipe (1) is annularly bulged outwardly in the molding space (31) formed by the inclined surface (13) of the mounting ring (11) and the vertical wall (12), and the pipe A bulging portion (2) is formed at the end (1a).

  In the bulging portion forming device of the present invention, the female screw portion (9) of the mounting ring (11) is screwed into the male screw portion (14) of the pipe head (16), so that a plurality of bolts for fixing the mounting ring (11) are fixed. Mounting of the mounting ring (11) of the bulging part forming device (50) is not required to be provided on the bulging part forming device (50) or the pipe expansion head (16), and does not depend on the outer diameter of the flange part. The size of the bulging part forming device (50) or the pipe expansion head (16) can be reduced, the entire bulging part forming device (50) can be reduced in size and weight, and the bulging part forming device (50) can be transported. Easiness and mobility at construction site can be improved. In addition, a steel pipe (31) in the axially asymmetric molding space (31) formed by the head inclined surface (15) of the pipe expansion head (16), the inclined surface (13) of the mounting ring (11) and the vertical wall (12). By projecting the tube end (1a) of 1) to the outside in an annular shape, the constrained portion on the outer diameter side of the bulge portion (2) is reduced, and the bulge portion of a predetermined height with a low molding load (2) can be formed.

  The flange-type pipe joint according to the present invention achieves a small size and light weight, and in particular, can connect a thin stainless steel pipe having an outer diameter of 76.3 mm (JIS G 3448, called 75 Su) or more simply and reliably on the construction site. Since the phenomenon does not occur, the workability is excellent and stable water stopping performance can be secured. Moreover, the bulging part forming apparatus according to the present invention can reduce the size and weight of the bulging part forming apparatus (50) accompanying the construction, and can easily carry the bulging part forming apparatus (50) to field work.

  Embodiments of a flange-type pipe joint, a steel pipe bulge portion forming apparatus, and a bulge portion forming method according to the present invention will be specifically described below with reference to FIGS.

  FIG. 1 shows a partially enlarged view of a flange-type pipe joint according to an embodiment of the present invention, and FIG. 2 shows a sectional view of the entire flange-type pipe joint. As shown in FIG. 1, the flange-type pipe joint of the present invention includes a through hole (10a), an annular groove (3) formed at an end of the through hole (10a), and a plurality of bolt holes (10c) concentrically. A joint body (10) having a flange portion (10b) formed with, a packing (4) mounted in an annular groove (3) of the joint body (10), and a through-hole (10a ), An attachment ring (11) having an opening (11a) that aligns with the opening, an inclined surface (13) that communicates with the opening (11a), and a coaxial hole (11b) that aligns with the bolt hole (10c) of the joint body (10). And a bolt (7) inserted into the bolt hole (10c) of the flange portion (10b) of the joint body (10) and the coaxial hole (11b) of the mounting ring (11) and a nut attached to the bolt (7) (8). The joint body (10) and the mounting ring (11) are formed of, for example, a stainless steel casting, and the mounting ring (11) is a flange portion (10) of the joint body (10) by a bolt (7) and a nut (8). 10b) is detachably fixed.

  The bolt hole (10c) of the flange part (10b) has a circular hole (10h) and a step part (10f) formed by an oval or elliptical non-circular hole (10i). The neck portion (7a) of the bolt (7) having a cross-sectional shape complementary to the step portion (10f) of the oval or elliptical non-circular hole (10i) is fitted into the step portion (10f), and the bolt hole (10c) The rotation of the bolt (7) inside is prevented. The step part (10f) of the oval or elliptical non-circular hole (10i) is slightly larger than the oval shape of the bolt neck lower part (7a), and the bolt neck lower part is fitted to prevent rotation when tightening. It has the function of. In the illustrated example, the sleeve (5) is disposed in the circular hole (10h) of the bolt hole (10c) of the joint body (10), and a single sleeve is provided on the inner surface of the sleeve (5) as shown in FIGS. Alternatively, a plurality of annular protrusions (5a, 5b) are provided. Bolts (7) are placed through the sleeve (5), and the annular protrusions (5a, 5b) are locked to the screw threads of the bolts (7), so that the bolts (7) in the bolt holes (10c) Movement or dropout can be prevented. As a result, the bolt (7) can be prevented from falling off from the flange (10b) at the time of construction and transportation, and it can be easily constructed without holding the bolt (7) by hand, thereby reducing the construction time. Demonstrate. The female thread portion (9) formed on the inner periphery of the attachment ring (11) has a larger diameter than the top portion (2c) of the bulging portion of the steel pipe (1). When connecting the steel pipe (1), the pipe end of the steel pipe (1), which is inserted into the mounting ring (11) and formed the bulging part (2), is inserted into the fitting body (10), and the mounting ring (11 ) The coaxial hole (11b) provided in the fitting (10) is aligned with the bolt hole (10c) of the flange (10b) of the joint body (10), and the nut (8) is screwed onto the bolt (7) to attach the flange (10b). Bonding is completed when the surface (10g) and the receiving surface (11d) of the mounting ring (11) are brought into close contact with each other.

  The pipe end (1a) of the thin and stainless steel pipe (1) inserted and fitted into the through hole (10a) of the joint body (10) and the opening (11a) of the mounting ring (11) is substantially circular. An annular bulge portion (2) having an arcuate cross section is formed. The top part (2c) of the bulging part (2) is arranged with a gap from the hole end part (10d) of the joint body (10) and the female thread part (9) of the mounting ring (11). In the annular groove (3) of the joint body (10), a taper surface inclined inward in the axial direction from the annular edge (3a) toward the radially outer diameter side is formed on the axially inner side. When a tapered surface inclined inward in the axial direction from the annular edge (3a) toward the radially outer diameter side is formed on the inner side in the axial direction of the annular groove (3) holding the packing (4), the packing (4) Is stably held to prevent falling off, and when pulling out the steel pipe (1) inserted into the through hole (10a), the packing (4) is moved to the annular groove (3) and removed without dropping. It can be securely held in the groove (3). In the embodiment of the present invention, a steel pipe (1) having an outer diameter of 76.3 mm (referred to as JIS G 3448 75 Su) or more is selected. The coaxial hole (11b) of the mounting ring (11) formed in a circular cross section has a circular cross section and a step having a shape such as an ellipse or an ellipse, similar to the bolt hole (10c) formed in the joint body (10). A sleeve (5) may be provided in the coaxial hole (11b).

  As shown in FIG. 6, the mounting ring (11) includes a coaxial hole (11b) aligned with the bolt hole (10c) of the joint body (10) and the maximum outer diameter of the bulging portion (2) of the steel pipe (1). A female thread (9) formed with a larger inner diameter, a vertical wall (12) adjacent to the female thread (9), and an outer inclined surface (2b) of the bulge (2) adjacent to the vertical wall (12) And an inclined surface (13) abutting on the surface. The top part (2c) of the bulging part (2) is from a hole end part (10d) provided on the axially outer side from the annular groove (3) of the joint body (10) and a female thread part (9) of the mounting ring (11). Separate radially inward.

  When connecting the pipe ends (1a) of the pair of steel pipes (1) with flange-type fittings, the bulging part forming device (50) is attached to the pipe end (1a) of the thin steel pipe made of stainless steel (1). Is used to form the bulging portion (2) on the tube end side from the mounting ring (11). Subsequently, the pipe end part (1a) of the steel pipe (1) is inserted into the through hole (10a) of the joint body (10), and the pipe end side of the bulging part (2) formed in the steel pipe (1) The inclined surface (2a) is brought into contact with the packing (4). Insert the bolt (7) through the bolt hole (10c) of the flange (10b) of the joint body (10) and the coaxial hole (11b) of the mounting ring (11), and together with the nut (8), the steel pipe (1) The flange portion (10b) of the joint body (10) and the mounting ring (11) are tightened by sandwiching the bulging portion (2) of the joint. Until the mounting surface (10g) of the flange portion (10b) of the joint body (10) and the receiving surface (11d) of the mounting ring (11) are in contact with each other on the radially outer side of the top portion (2c) of the bulging portion (2). By tightening the bolt (7) and nut (8) in the final tightened state, the annular edge (3a) provided axially inside from the annular groove (3) of the joint body (10) Of the pipe end side inclined surface (2a) or the pipe end side inclined surface (2a) adjacent thereto and the mounting ring (11) on the other inclined surface (2b) of the bulging portion (2) The swelled part (2) of the steel pipe (1) is sandwiched between the joint body (10) and the mounting ring (11), and the steel pipe is tightened with a flanged pipe joint in the final tightened state. Connect (1).

  When the pipe ends (1a) of a pair of steel pipes (1) are connected by the flange-type pipe joint in the final tightened state, the annular edge (3a) provided axially inward from the annular groove (3) of the joint body (10) (1) A joint body (a) that forms a through hole (10a) in contact with the rising part of the pipe end side inclined surface (2a) of the bulging part (2) or the pipe end side inclined surface (2a) adjacent to the rising part. The inner surface of 10) and the outer surface of the steel pipe (1) are in contact with each other to form a first sealing structure by contact between metals. In addition, the tube end side inclined surface (2a) of the bulging portion (2) disposed at the back of the through hole (10a) is in contact with the packing (4) to form a liquid-tight structure or a water-tight structure. That is, the packing (4) is elastically contacted with the inner inclined surface (2a) of the bulging portion (2) outside the annular edge (3a) in the axial direction, and the second sealing structure by the elasticity of the packing (4). Is formed. In this way, pulsation or pressure fluctuation occurs in the fluid in the steel pipe (1) by the double sealing structure of the first sealing structure by the metal-to-metal contact and the second sealing structure by the elastic contact of the packing (4). Even in this case, it is possible to completely prevent the fluid in the steel pipe (1) from leaking between the outer surface of the steel pipe (1) and the joint body (10). In this way, the joint body (10), the steel pipe (1), and the packing (4) form the first and second sealing structures that form a double liquid-tight structure or a double water-tight structure, thereby producing a water stop function. Further, it is not necessary to use the holding ring and gasket packing disclosed in Patent Document 2, and the first and second sealing structures can reduce the number of parts and reduce the weight of the flange-type pipe joint. In addition, since there is no water stop structure on the joint surface between the mounting surface (10g) of the flange portion (10b) and the receiving surface (11d) of the mounting ring (11), the joint surface can be machined with high precision, It is not necessary to equalize the tightening torque between the bolts, and the manufacturing cost can be reduced. When tightening the joint body (10) and the mounting ring (11) by tightening the bolt (7) and nut (8), the mounting surface (10g) of the flange (10b) of the joint body (10) Since the receiving surface (11d) of the mounting ring (11) abuts, an excessive compressive force is not applied to the packing (4) held in the annular groove (3), and the packing (4) is damaged and moved. Can be prevented. Further, after assembly, the bulging portion (2) of the steel pipe (1) is securely sandwiched between the joint body (10) and the mounting ring (11), and the bulging portion (2) and the steel pipe (1) Axial movement is prevented.

  The packing (4) attached to the annular groove (3) of the joint body (10) and closely attached to the expanded portion (2) of the steel pipe (1) is 8 to 40%, preferably 20 to 30%. The compression rate is maintained. The first sealing structure by metal-to-metal contact has a pressure resistance of 1 to 2 MPa in the seal structure by metal contact between the annular edge (3a) and the rising part of the pipe end side inclined surface (2a) or its adjacent part. It is preferable to show performance. This reduces the high level of heat resistance and mechanical strength required for packing materials used in cold / hot water pipes, especially heat resistance, enables the use of general-purpose rubber materials, and reduces the cost of flange-type fittings. Is possible. In addition, even if the bulging part (2) expands or contracts in the axial direction due to thermal influence due to high or low temperature internal fluid or outside air or ambient temperature, the joint body (10) and the mounting ring (11) are firmly connected. The joint can suppress the axial deformation of the bulging portion (2) and prevent the sealing performance from deteriorating. In the embodiment of the present invention, since the number of components can be reduced compared to the conventional connection structure in which water sealing and sealing between the flange surfaces are performed with separate packing and gasket packing, occurrence of problems during construction is prevented, and parts management is performed. Man-hours can be reduced.

  On the radially inner side of the receiving surface (11d) of the mounting ring (11), there is an internal thread portion (9) formed on the circumferential inner surface with an inner diameter larger than the maximum outer diameter of the bulging portion (2) of the steel pipe (1). The space portion (30) is formed by the vertical wall (12) formed on the radially inner surface adjacent to the female screw portion (9). An inclined surface (13) is formed on the radially inner side of the vertical wall (12) adjacent to the vertical wall (12), and an opening (11a) is formed on the outer side in the axial direction of the inclined surface (13). It is formed. The top part (2c) of the bulging part (2) is radially inward from the hole end part (10d) of the joint body (10) and the female thread part (9) of the mounting ring (11) through the space part (30). Separate. Further, the vertical wall (12) is spaced outward from the mounting surface (10g) of the flange portion (10b) via the space portion (30) in the axial direction. Therefore, even when the bulging portion (2) increases in the radial direction when the steel pipe (1) is connected or thermally expanded, the top (2c) of the bulging portion (2) and the hole end portion of the joint body (10) ( Since the space portion (30) is provided between 10d) and the female thread portion (9), the steel pipe (1) and the joint body (10) are not in contact with each other, and the influence of thermal expansion / contraction on the sealing function can be reduced.

  The bulging part (2) formed on the steel pipe (1) at room temperature is slightly expanded by the spring back characteristic of the steel pipe (1) itself after being expanded by the elastic member (18) of the bulging part forming device (50). Reduce to diameter. As a result, when the steel pipe (1) is connected to the through hole (10a) of the joint body (10), the rising portion of the formed bulge portion (2) or its adjacent portion is preferentially given to the annular edge portion (3a). Abut. Here, the adjacent portion is preferably about 10% of the linear distance from the rising portion to the maximum diameter portion (2c) of the bulging portion (2). In this state, when an internal pressure is applied to the steel pipe (1), a high pulling out prevention force can be secured. When an external force directed radially inward is applied to the top surface (2c) of the bulge portion (2) or an inclined surface near the top portion (2c), the bulge portion (2) is deformed even at a low load, and the deformation occurs once. Then, it becomes difficult to ensure a high pulling-out prevention force of the steel pipe from the flange type pipe joint. In this case, if the height of the bulging portion (2) is simply formed large, it is possible to prevent a decrease in the pulling-out prevention force of the bulging portion (2), but the deformation amount of the steel pipe that is an austenitic stainless steel Increases, the amount of work-induced martensite increases and the corrosion resistance of the steel pipe significantly decreases. Therefore, in the present invention, the annular edge (3a) provided on the inner side in the axial direction from the annular groove (3) of the joint body (10) is brought into contact with the pipe end side inclined surface (2a) of the bulging portion (2). As will be described later, a space portion (30) formed by the hole end portion (10d) of the joint body (10), the vertical wall (12) of the mounting ring (11), and the female thread portion (9) is provided to swell. The bulging portion (2) is sandwiched between the joint body (1) and the mounting ring (11) without applying an external force to the top portion (2c) or the vicinity of the top portion (2c) of the protruding portion (2). As a result, it is possible to minimize the amount of deformation of the bulging portion (2) and to generate the maximum pull-out prevention force while suppressing the generation of the processing-induced martensite amount to the limit.

  The bulging part forming device (50) shown in FIGS. 8 to 10 which forms the bulging part (2) in the steel pipe (1) is fixed to the base (25) and has a male screw (14) formed at the tip part. A pipe expansion head (16), a shaft (21) movably inserted into a central hole (16a) of the pipe expansion head (16), and a male screw (22) formed at the end of the shaft (21). A pipe guide (20) having a recess (20b) in which a female screw (20a) to be joined is formed, and an elasticity extrapolated between the annular notch (20c) of the pipe guide (20) and the pipe expansion head (16) A member (18) and a spacer (19) juxtaposed between the elastic member (18) and the axially inner surface (16b) of the tube expansion head (16) on the annular notch (20c) of the tube guide (20) Is provided. The elastic member (18) is made of rubber or elastomer, and the spacer (19) is made of resin or metal. The tube expansion head (16) has a male screw portion (14) provided on the outer surface of the support end portion (16d) and a head inclined surface (15) provided on the inner surface of the support end portion (16d). The tube guide (20) is held coaxially with the tube expansion head (16) so as to be movable forward and backward in the axial direction with respect to the tube expansion head (16).

  When forming the bulging part (2) at the pipe end (1a) of the steel pipe (1) using the bulging part forming device (50), the pipe expansion head is placed on the vertical wall part (12) of the mounting ring (11). The female screw portion (9) formed on the mounting ring (11) is screwed and fixed to the male screw portion (14) of the tube expansion head (16) until the support end portion (16d) of (16) comes into contact. Thus, the mounting ring (11) is attached to the tube expansion head (16) of the bulging portion forming device (50) by the female thread portion (9) provided on the inner peripheral portion of the mounting ring (11), and the flange outer diameter Regardless of the dimensions, the tube expansion head (16) can be downsized, and the entire bulge forming device (50) can be reduced in size and weight. Improved mobility.

  Next, in the cylindrical space (24) formed between the opening (11a) of the mounting ring (11) and the pipe expansion head (16) and the pipe guide (20), the elastic member (18) and the spacer (19). The tube end (1a) of the thin-walled stainless steel pipe (1) is inserted into the tube, and the tube end (1a) is brought into contact with the axially inner surface (16b) of the tube expansion head (16). That is, the pipe end (1a) of the steel pipe (1) is inserted outside the pipe guide (20) and into the opening (11a) of the mounting ring (11), passes through the elastic member (18), and passes through the steel pipe. Insert the pipe end (1a) of (1) between the pipe expansion head (16) and the spacer (19), so that the pipe end (1a) contacts the axial inner surface (16b) of the pipe expansion head (16). Make contact. In this state, the tube end (1a) reaching the axially inner surface (16b) of the tube expansion head (16) is visually confirmed through a confirmation hole (17) provided in the tube expansion head (16).

  Thereafter, when the shaft (21) is moved in the direction F shown in FIG. 9 by a hydraulic device or pneumatic device (not shown), the tube guide (20) is moved in the same direction as the shaft (21), and the elastic member ( 18) is compressed and the elastic member (18) expands and expands in the radial direction by the volume corresponding to the reduced axial width, so that the outer peripheral surface of the elastic member (18) is radially outward. The steel pipe (in the molding space (31) formed by the head inclined surface (15) of the tube expansion head (16), the inclined surface (13) of the mounting ring (11), and the vertical wall (12) is thereby deformed. A part of the tube end portion (1a) of 1) is projected outwardly in an annular shape to form a bulging portion (2) at the tube end portion (1a). As shown in FIG. 10, the length of the inclined surface (13) formed on the inner peripheral side of the mounting ring (11) is set to the length of the head inclined surface (15) formed on the inner diameter portion of the tube expansion head (16). The molding space (31) for forming the bulging portion (2) at the pipe end (1a) of the steel pipe (1) is formed in an axially asymmetric shape. On the outer periphery of the steel pipe (1) with the elastic member (18) disposed on the inner peripheral side, the head inclined surface (15) of the pipe expansion head (16), the inclined surface (13) of the mounting ring (11) and the vertical wall (12 As a result, the steel pipe (1) is expanded by the expansion of the elastic member (18) in the outer radial direction. ) And the contact portion (16c) of the steel pipe (1) and the contact portion (11c) of the mounting ring (11) and the steel pipe (1). At this time, the asymmetrical substantially arrow-shaped molding space (31) formed by the pipe expansion head (16) and the mounting ring (11) relaxes the restraint of the bulging portion (2) of the steel pipe (1) and is low. The bulging portion (2) having a predetermined height can be formed by the molding load. As a result, the bulging portion forming device (50) can be configured using small parts, and the entire device can be reduced in size. At the same time, the weight of the entire product can be reduced by forming the mounting ring (11) with a minimum thickness. Further, the other inclined surface (2b) formed by the inclined surface (13) of the mounting ring (11) of the bulging portion (2) is inclined on the tube end side by the head inclined surface (15) of the tube expansion head (16). Since the amount of springback is smaller than that of the surface (2a), the other inclined surface (2b) having an arc shape that is larger by the difference in the amount of springback is formed, so that it is possible to further strengthen the pull-out prevention force from the flange-type fitting. .

  For example, in the conventional pipe expanding apparatuses disclosed in Patent Documents 1 to 3, the outer peripheral surface of the steel pipe is brought into close contact with the entire inclined surface of the molding space having a chevron-shaped cross section formed by the pipe expanding head and the clamping member (nut). The steel pipe is swelled into a shape, but in the pipe expanding device of the present invention, the inclined surface (13) of the mounting ring (11) is formed with a length shorter than the length of the head inclined surface (15) of the pipe expanding head (16). Then, the bulging portion (2) is formed. The bulging end formed at the start of bulging of the steel pipe (1) is in contact with and securely held in contact with the contact portion (16c) of the pipe expansion head (16) and the contact portion (11c) of the mounting ring (11). If the outer surface of the steel pipe (1) that bulges out from the contact portions (16c, 11c) using about 30% of the head inclined surface (15) and the inclined surface (13) is expanded, the steel pipe (1 ) Forms an almost uniform symmetrical bulge (2) from the center plane in the tube axis direction to the front and back without causing a sudden shape change due to its own rigidity and without causing abnormal deformation of the elastic member (18) can do. That is, on the tube end side inclined surface (2a) side of the bulging portion (2), 30% of the linear distance from the rising portion of the tube end side inclined surface (2a) to the top portion (2c) of the bulging portion (2). As described above, preferably, if the length of the inclined surface (13) of the mounting ring (11) is set to 30 to 50%, the bulging portion (2) having a symmetrical shape in the tube axis direction can be formed. As a result, in the conventional tube expansion method, the length of the entire bulging part is ½ in the axial direction (the length from the rising part of the pipe end side inclined surface (2a) to the top part (2c) of the bulging part (2). ), The length of the inclined portion of the mounting ring can be greatly shortened. Further, the internal thread portion (9) to be screwed to the tube expansion head (16) is provided on the inner surface of the mounting ring (11), so that the thickness of the mounting ring (11) can be reduced and the weight can be significantly reduced. In the embodiment of the present invention, the mounting ring (11) is 40% of the linear distance from the rising portion of the inclined surface (2a) of the tube end side of the bulging portion (2) to the top portion (2c) of the bulging portion (2). The length of the inclined surface (13) was set to perform molding.

  Further, it is not necessary to provide a plurality of bolt fixing portions for attaching the mounting ring (11) to the bulging portion forming device (50) or the tube expansion head (16), and the bulging portion is not dependent on the outer diameter of the flange portion. Since the mounting portion of the mounting ring (11) of the forming device (50) can also be reduced in size, the bulging portion forming device (50) or the tube expansion head (16) can be downsized to reduce the size of the entire bulging portion forming device (50). Weight reduction, ease of carrying the bulge forming device (50), and mobility at the construction site can be improved.

Table 1 shows a comparative example of the flange-type pipe joint of the present invention and a conventional pipe joint according to JIS B 2220. Table 1 shows steel pipe diameters according to JIS G 3448 designations 75Su, 80Su, 100Su (65A, 80A, 100A). As shown in Table 1, in the flange-type pipe joint of the present invention, the flange outer diameter is reduced by about 9 to 14%, the flange thickness is reduced by about 32 to 35%, and the flange thickness is reduced by 1 to 1 compared with the conventional pipe joint. The effect of reducing the diameter of the 2-rank bolt and halving the number of used bolts can be obtained, but the present invention is not limited to these numerical values.

  In addition, the flange-type pipe joint of the present invention, which provides a stable sealing function, eliminates the need for bolt tightening torque management and has a flange portion with a small outer diameter and a small gap. Can be easily passed through the through-hole formed in the wall of the building in the assembled state and can easily wrap the heat insulating material, so the workability is greatly improved, the piping work is simplified and the construction period is shortened Can contribute.

  The present invention is suitable for a flange-type pipe joint that connects thin stainless steel pipes.

Partial enlarged sectional view of a flange-type pipe joint according to the present invention Sectional drawing which shows the whole of the flange type pipe joint by this invention which connects a thin stainless steel pipe The partial side view which shows the bolt hole formed in the flange part of the flange type pipe joint shown in FIG. Top perspective view of sleeve mounted in bolt hole Cross section of sleeve Partial sectional view of the mounting ring Front view of mounting ring Sectional drawing which shows the bulging part formation apparatus before pipe expansion operation Sectional drawing which shows the bulging part formation apparatus after tube expansion operation Partial sectional view of the bulge forming device

Explanation of symbols

  1. Steel pipe, 1a. 1. tube end, Bulge, 2a. Pipe end side inclined surface, 2b. The other inclined surface, 2c. 2. top, An annular groove, 3a. 3. tubular edge; Packing, 5. Sleeve, 7. Bolt, 7a. Bolt neck lower part, 8. Nuts, 9. Internal thread, 10. Coupling body, 10a. Through hole, 10b. Flange part, 10c. Bolt holes, 10f. Step part, 11. Mounting ring, 11a. Opening, 11b. A coaxial hole, 11c. Contact part, 11d. Receiving surface, 12. Vertical wall, 13. Inclined surface, 14. Male thread part, 15. 15. head inclined surface; Expansion head, 16a. Center hole, 17. Visual hole, 18. 18. elastic member, Spacers, 20. Pipe guide, 21. Shaft, 24. Cylindrical space, 25. Base, 30. Space part, 31. Molding space, 50. Bulge forming device,

Claims (6)

A joint body having a through-hole, a flange formed with an annular groove and a bolt hole formed at an end of the through-hole, and
Packing installed in the annular groove of the joint body;
An opening that matches the through hole of the joint body, an inclined surface formed in communication with the opening, a mounting ring that has a coaxial hole that matches the bolt hole of the joint body, and
A bolt inserted through the bolt hole of the flange portion of the joint body and the coaxial hole of the mounting ring and a nut attached to the bolt;
The tube end side inclined surface of the bulging portion formed at the tube end portion of the thin and stainless steel pipe inserted into the through hole of the joint body and the opening of the mounting ring is in contact with the packing,
When a bolt and a nut are fastened and the mounting surface of the flange portion of the joint body and the receiving surface of the mounting ring come into contact with each other on the radially outer side of the top of the bulging portion, they are provided on the axially inner side from the annular groove of the joint body. The annular edge is in contact with the rising portion of the inclined surface on the tube end side of the bulging portion or its adjacent portion, and the inclined surface of the mounting ring is in contact with the other inclined surface of the bulging portion to be attached to the joint body. clamping the bulging portion of the steel pipe between the rings,
The mounting ring includes a female screw portion having an inner diameter larger than the maximum outer diameter of the bulging portion of the steel pipe, and a vertical wall adjacent to the female screw portion,
The inclined surface is formed adjacent to the vertical wall;
The flange-type pipe joint characterized in that the top part of the bulging part is spaced radially inward from the hole end part provided on the axially outer side from the annular groove of the joint body and the female thread part of the mounting ring . The flange-type pipe joint according to claim 1 , wherein the bolt hole of the joint body is formed by a circular through hole, an ellipse or an elliptical step. The flange-type pipe joint according to claim 1 or 2 , wherein a bolt is disposed through a sleeve disposed in a bolt hole of the joint body.   The length of the inclined surface of the mounting ring is 30% to 50% of the linear distance from the rising portion of the other inclined surface of the bulging portion to the top of the bulging portion. The flange type pipe joint described. A tube expansion head fixed to the base;
A tube guide that is held coaxially with the tube expansion head so as to be movable forward and backward in the axial direction with respect to the tube expansion head;
An elastic member disposed between the tube expansion head and the tube guide;
The tube expansion head has a center hole, a male screw portion provided on the outer surface of the support end portion, and a head inclined surface provided on the inner surface of the support end portion,
The female thread portion formed on the mounting ring having the inclined surface on the inner peripheral side is screwed into the male thread portion of the tube expansion head,
The pipe end of the thin and stainless steel pipe inserted into the cylindrical space formed between the opening of the mounting ring and the pipe expanding head and the pipe guide and the elastic member is in contact with the inner surface in the axial direction of the pipe expanding head.
By moving the tube guide toward the tube expansion head, the elastic member is compressed and expanded radially outward, thereby forming the inside of the molding space formed by the head inclined surface of the tube expansion head, the inclined surface of the mounting ring, and the female screw portion. In the steel pipe bulging portion forming apparatus, the length of the inclined surface of the mounting ring is the head of the pipe expanding head. An apparatus for forming a bulge portion of a steel pipe, which is shorter than an inclined surface. The steel pipe bulge part forming apparatus according to claim 5 , wherein a confirmation hole for visually recognizing an end part reaching the axial inner surface of the pipe expansion head is provided in the pipe expansion head.

Images