JP7679082B2 - Connection mechanism between steel pipe and fitting - Google Patents

Description

This invention relates to a connection mechanism between steel pipes and fittings that is primarily used for indoor piping in buildings.

A conventional technique for this type of connection mechanism between a steel pipe and a joint is the connection mechanism shown in Patent Document 1, which was proposed by the applicants. This connection mechanism is a connection mechanism that can firmly connect a joint body having an engaged part at its end and a lock ring holder having an engaging ring part at its end, into which the engaged part is inserted and engaged, by pushing and inserting an engaging protrusion on the outer periphery of the engaged part deep into the inner periphery through an opening notch on the inner periphery of the lock ring holder, and then rotating and inserting it into an engaging hole on the inner periphery that communicates with the opening notch. The lock ring holder and the joint are normally prevented from moving in the direction of removal from the steel pipe, and are themselves biased in the direction of removal by the lock ring, so that friction between the engaged part and the inner surface of the engaging hole becomes large, preventing rotation in the circumferential direction and preventing loosening.

The connection mechanism between a steel pipe and a fitting in Patent Document 2 connects a fitting with a male thread formed on the outer periphery of the end portion to a nut with a female thread formed for inserting the fitting inside and engaging it by inserting the end portion of the fitting into the inside of the nut and rotating the nut to screw the female thread onto the male thread. At this time, the inclined surface on the end side of the mountain-shaped protrusion is pressed by the corner of the fitting and the inclined surface on the opposite side is pressed by the inclined corner of the nut, preventing the steel pipe with the mountain-shaped protrusion from moving in the axial direction and completing the connection. The inclined corner of the nut uses the same parts of the pipe expander used to expand the end portion of the steel pipe into a mountain shape, so the inclined surface of the mountain-shaped protrusion and the inclined corner have a completely matching inclination angle and surface shape, ensuring close contact.

Patent No. 4352434 WO2009/050823 publication

However, according to the conventional technology of Patent Document 1, when connecting the joint body and the lock ring holder, the joint body has an engaged part with a male thread at its end, and the lock ring holder has an engaging ring part with a female thread at its end, which engages when the engaged part is inserted inward, and is connected by screwing. This creates a problem in that the screw connection can loosen due to vibrations and aging of the structure caused by years of use, which can cause leakage of fluid passing through the inside of the steel pipe.

In addition, in the conventional technology of Patent Document 2, the male thread formed on the outer periphery of the end of the joint is screwed into the female thread formed on the inner periphery of the nut to connect them, so there is the same problem as above that the screw connection may loosen due to vibrations and aging of the building over many years of use, which may cause leakage of fluid passing through the inside of the steel pipe.

This invention was made to solve the above problems, and its means of doing so are as follows:

A connection mechanism between a steel pipe and a fitting, in which a steel pipe having a mountain-shaped protrusion on its end side is connected by sandwiching it between a fitting and a nut, said fitting having a medium expansion section on the inner periphery side of a connecting cylindrical section at the end of a connecting cylindrical section having a fluid passage inside, and further having a packing storage section which is a large expansion section with an even larger diameter than the medium expansion section and which opens to the end, on the end side of said medium expansion section, and a flange section which extends outward on the outer periphery near the boundary between said connecting cylindrical section and said connecting cylindrical section, and a plurality of engaging blades are provided at the tip of the outer periphery of said connecting cylindrical section at a predetermined interval in the circumferential direction, and a plurality of engaging blades are provided at a predetermined interval in the axial direction from said engaging blade and in the circumferential direction of said engaging blade. A plurality of stoppers are provided so as to be positioned between the widthwise intervals of the open engagement blades, and the nut has an annular outer tubular portion that fits the outer periphery of the engagement blades of the connection tubular portion, and a steel pipe pressing portion that forms a pipe insertion hole in the center at one end side of the annular outer tubular portion and is equipped with an inclined pressing surface that presses the inner side inclined surface of the mountain-shaped protrusion of the steel pipe, and on the inner circumference of the annular outer tubular portion, a final fastening ring and a temporary fastening ring are provided at a predetermined interval in the axial direction and are mutually inseparable and rotatable in the circumferential direction, in order from the side closest to the inclined pressing surface, and the temporary fastening ring is arranged rotatably together with the annular outer tubular portion, while the final fastening ring is arranged at a predetermined The main tightening ring and the temporary tightening ring are capable of independent rotation by a certain angle, and a main tightening blade and a temporary tightening blade, each having a predetermined circumferential length and a predetermined protruding height toward the center, are provided on the inner peripheral side of the main tightening ring and the temporary tightening ring at an interval equal to or greater than the circumferential length of the engagement blade, and the end side of the steel pipe inserted into the pipe insertion hole of the nut is inserted into the connection cylindrical portion, and the end side inclined surface of the mountain-shaped protrusion is pressed by the packing stored in the packing storage portion, and the inner side inclined surface of the mountain-shaped protrusion is pressed by the inclined pressing surface, whereby the temporary tightening blade of the temporary tightening ring comes into contact with the stopper and is locked so as not to move in the axial direction, and The connection mechanism for a steel pipe and a joint is characterized in that, when the final tightening blade is sandwiched between the engaging blades and cannot rotate, the nut is rotated to position the pre-tightening blade on the side of the engaging blade to prevent movement in the removal direction, and then the gap between the nut and the joint is further tightened to reduce the packing, and the final tightening ring is rotated to perform final tightening so that the final tightening blade is positioned on the side of the engaging blade in a state where it cannot move, thereby connecting and fixing the joint and the nut in a mutually non-rotatable state while preventing the force of the connecting tube portion in the removal direction from the annular outer tube portion.

The structure in which the main tightening ring and the temporary tightening ring are arranged on the inner circumference of the annular outer cylinder at a predetermined distance in the axial direction so that they cannot move away from each other and can rotate freely in the circumferential direction is characterized in that the outer circumferences of the main tightening ring groove and the temporary tightening ring groove arranged at a predetermined distance in the axial direction from the main tightening ring groove are fitted rotatably into each other.

The main tightening ring and temporary tightening ring are elastic rings with hooks or locking heads at both ends of the cutout, which acts as a connection mechanism between the steel pipe and the fitting.

The main tightening ring is made of metal material and the temporary tightening ring is made of synthetic resin material to connect the steel pipe and the joint.

The connecting mechanism between the steel pipe and the joint is provided with a rotation stop bar that provides a predetermined distance in the axial direction between the stop block and the engaging blade interval .

The provisional fastening ring has a locking head provided at both ends of the provisional notch , the locking head having a bulge in the direction of the final fastening ring, thereby forming a connection mechanism between the steel pipe and the joint.

The connection mechanism between the steel pipe and the joint is characterized by the provision of a locking protrusion on the outer periphery near the hook portion of the tightening ring.

According to this invention, when connecting a steel pipe having a mountain-shaped protrusion on the end side to a fitting, the inclined pressing surface of the nut is placed against the inner inclined surface of the mountain-shaped protrusion of the steel pipe inserted into the pipe insertion hole of the nut, the connecting tube of the fitting is inserted into the annular outer cylindrical part of the nut, and then the nut is rotated to temporarily connect the fitting and the nut with the temporary tightening ring, and after tightening, the final connection is made by rotating the final tightening ring, which firmly connects the fitting and the nut. After connection, the final tightening ring and the temporary tightening ring will not loosen the connection even due to vibrations of the building over many years. Also, when a tensile force is applied to the steel pipe, the final tightening ring fixed to the nut will not come out because the force in the pull-out direction is prevented by the engaging blade of the fitting. At the same time, the packing crimped to the end side inclined surface will not loosen, effectively preventing fluid leakage.

If the structure in which the main fastening ring and the temporary fastening ring are arranged on the inner circumference of the annular outer cylinder at a predetermined distance in the axial direction so that they cannot move away from each other and can rotate freely in the circumferential direction is such that the outer circumferences of the main fastening ring grooves on the inner circumference of the annular outer cylinder and the temporary fastening ring grooves arranged at a predetermined distance in the axial direction from the main fastening ring grooves are fitted rotatably, the rings can rotate freely on the inner circumference of the annular outer cylinder but cannot move in the axial direction, i.e. they can be strongly prevented from moving against forces in the pull-out direction, and the temporary fastening ring and the main fastening ring can be easily attached and detached.

The main and temporary fastening rings are elastic rings with hooks or locking heads on both ends of the notch, so the diameter can be changed by deforming the ring, making them easy to attach to and detach from the main and temporary fastening ring grooves. The hooks and locking heads prevent the notch of each ring from getting into the respective grooves.

If the temporary fastening ring is made of a synthetic resin material, the fastening head and other parts can be molded more easily than with metal, and the material costs are also lower. If the final fastening ring is made of a metal material, it is highly durable and can withstand many years of use.

When the anti-rotation rod is installed, the tightening ring and the temporary tightening ring can slide easily in the axial direction when the nut is pushed in, and the nut can be prevented from rotating.

If the locking heads at both ends of the temporary fastening ring are given a bulge in the width direction, a predetermined distance can be maintained between the main fastening ring and the temporary fastening ring in an opening that does not have a ring groove, so that the distance between the main fastening ring and the temporary fastening ring can be appropriately maintained even in the opening.

If a locking projection is provided on the outer circumference near the hooks at both ends of the final tightening ring, this locking projection will lock into the peripheral walls at the entrance to each groove, preventing the final tightening ring from loosening during provisional tightening and final tightening.

The method has two steps: a temporary tightening process in which the two inclined surfaces of the mountain-shaped protrusions formed on the end of the steel pipe are sandwiched between the joint and the nut, and the joint and the nut are moved in a direction to approach each other so as to hold the steel pipe, and then the temporary tightening process is performed. After the temporary tightening process, the joint and the nut are further tightened in a direction to bring them closer together to make a permanent connection. That is, first, a piping network temporarily connected by a temporary tightening ring is temporarily constructed. By repeating the same work for many joints and pipes, piping work on site can be efficiently performed. For example, piping installation work can be efficiently performed by temporarily constructing a piping network suspended by wire near the installation location, further tightening the joints and nuts, and then rotating the tightening ring to make a permanent connection and fix it to the installation location. In addition, when removing this constructed piping network for repairs, etc., it can be easily performed by simply rotating the tightening ring and nut in the opposite direction to the direction of rotation when connecting them.

The temporary and final connections are performed by rotating the temporary and final tightening rings provided on the nut together with the nut or within the nut to engage with the joint, making the work simple and efficient.

The temporary fastening ring is made of a synthetic resin material and the main fastening ring is made of a metal material, so the temporary fastening ring, which connects temporarily, is easy to mold and can be made of inexpensive materials, while the main fastening ring, which connects for many years, is made of a metal material and is therefore durable and strong.

FIG. 1 is a cross-sectional perspective view of a steel pipe and a joint according to an embodiment of the present invention; FIG. 2 is an exploded perspective view of FIG. Front perspective view of the nut from the joint side Partial cross-sectional view taken along line XX in FIG. 4 is a partial cross-sectional view taken along line Y-Y of FIG. A perspective view of the joint and nut just before they are connected FIG. 1 is a perspective view of a joint showing the positional relationship between the final fastening blade, the temporary fastening blade, and the engagement blade when the nut is fitted into the joint; FIG. 13 is a front perspective view showing how the temporary locking protrusion of the final fastening ring is locked to the wall of the opening. An explanatory diagram of the inside of the nut in which the temporary fastening ring is rotated together with the nut to move the temporary fastening blade to the side of the engagement blade. FIG. 10 is a perspective view of a joint showing the positional relationship between the main fastening blade, the temporary fastening blade, and the engagement blade of FIG. FIG. 10 is an explanatory diagram of the inside of the nut when the joint and the nut are tightened in the direction approaching each other from the state of FIG. 9. FIG. 12 is a perspective view of a joint showing the positional relationship between the main tightening blade, the provisional tightening blade, and the engagement blade of FIG. FIG. 12 is an explanatory diagram of the inside of the nut when the joint and the nut are brought closer together from the state of FIG. 11 and then the final tightening ring is rotated to final tighten the nut. FIG. 14 is a perspective view of the joint showing the positional relationship between the main fastening blade, the temporary fastening blade, and the engagement blade of FIG. FIG. 15 is a front perspective view showing how the fastening projection of the fastening ring of FIG. 13 and FIG. 14 is engaged with the opening wall; A perspective view of the appearance of the joint and nut with the opening in the center at the time of completion of connection Cross-sectional view of a pipe expander for forming angled protrusions on steel pipes

The best mode for carrying out the present invention for implementing the connecting mechanism between a steel pipe and a joint will now be described with reference to the accompanying drawings.
As shown in Figure 1, this connection mechanism 1 between a steel pipe and a fitting is a connection mechanism in which the tip of a steel pipe 2 is inserted into the end of a fitting 3, and the end side inclined surface 21a and the inner side inclined surface 21b of a mountain-shaped protrusion 21 formed on one end 2a of the steel pipe 2 are clamped and fixed between the connected fitting 3 and nut 4 to connect them.

The steel pipe 2 is generally a thin, long pipe body made of stainless steel, iron, metal alloy, etc., having a mountain-shaped protrusion 21 consisting of two inclined surfaces, inclined surface 21a and inclined surface 21b, on one end 2a side, as described above, and its internal fluid passage is a passageway for liquids such as hot water and tap water, and gaseous fluids such as steam, gas, and air. These steel pipes 2 are mainly used for indoor piping in buildings, but since this piping work is often carried out at construction sites in narrow spaces, when it is difficult to transport and cut a long steel pipe 2 to the required length, the steel pipe 2 cut in advance at a factory, or even the joints 3 connected to these cut steel pipes 2 in advance, are transported to the construction site, or are connected, assembled, and laid on site.

The joint 3 has a connecting tube 31, the structural shape of which can be selected according to the construction site from among an L-shaped elbow, a T-shaped tee, a cross that branches in three directions, a reducer with different diameters at both ends, etc., and a connecting tube 32 provided at the end of the connecting tube 31. In addition, a flange 33 that is larger in diameter than the connecting tube 32 and extends outward on the outer periphery near the boundary between the connecting tube 31 and the connecting tube 32 is provided. As shown in Figures 1 and 2, in this embodiment, a short, straight fluid passage 34 with a hexagonal exterior and a circular interior is used as the connecting tube 31.

The connecting tubular portion 31 has the fluid passage 34 inside, the inner diameter of which is approximately equal to the inner diameter of the steel pipe 2. The connecting tubular portion 32, which is continuous with the fluid passage 34, is provided protruding from one or both ends of the connecting tubular portion 31, but Figs. 1 and 2 show an embodiment in which it is provided only at one end. The connecting tubular portion 32 has a medium expansion portion 35 on the inside, which has a larger diameter than the fluid passage 34 that passes through the outer periphery of the end 2a side of the steel pipe 2, and a large expansion portion 36, which is even larger in diameter than the medium expansion portion 35 and opens to the tip, is formed on the tip side of the medium expansion portion 35, and the difference wall surface 35a formed by the step between the large expansion portion 32 and the medium expansion portion 35 and the large expansion portion 36 form a packing storage portion 36a that stores annular packing 5.

7 , six arc-shaped rectangular parallelepiped engaging blades 2a are provided in a row in the circumferential direction at the tip of the outer periphery of the connecting tubular portion 32 with a distance K between the engaging blades 32a, and each of the engaging blades 32a has a circumferential length L, a widthwise length S which is also the axial direction of the center of the joint 3, and a protruding height H from the outer periphery of the connecting tubular portion 32. Furthermore, six rotation stop rods 32b are provided from one end side of each of the engaging blades 32a in the widthwise direction toward the flange portion 33, and are shorter than the protruding height H of the engaging blade 32a. In addition, six stop bases 32c are provided along the base of the flange portion 33 from the connection position of the rotation stop rods 32b with the flange portion 33, and are shorter than the rotation stop rods 32b, and have circumferential and widthwise lengths approximately equal to the length L and widthwise length S of the engaging blades 32a, respectively. The widthwise spacing between this stop plate 32 and the engaging blade 32a is slightly longer than the widthwise length S of the engaging blade 32a, and the stop plate 32 is disposed at a position not overlapping with the engaging blade 32a in the axial direction.

The nut 4 is a cap nut as shown in Figures 1 to 6, and includes an annular outer cylindrical portion 41 into which the connecting cylindrical portion 32 of the joint 3 is inserted for joining, and a steel pipe pressing portion 43 with a pipe insertion hole 42 formed in the center for inserting the steel pipe 2 at one end of the axial direction of the annular outer cylindrical portion 41. The inner peripheral surface of the annular outer cylindrical portion 41 is provided with a tapered inclined pressing surface 44, a circumferential tightening ring groove 45 into which the outer peripheral edge portion 61 of the tightening ring 6 is inserted, and a circumferential temporary tightening ring groove 46 into which the outer peripheral edge portion 71 of the temporary tightening ring 7 is inserted at a distance from the main tightening ring groove 45.

In this embodiment, as shown in Figures 4 and 5, the width thickness and diameter of the final tightening ring 6 and the temporary tightening ring 7 are formed to be equal, so the width and groove diameter of the final tightening ring groove 45 and the temporary tightening ring groove 46 are approximately the same. Furthermore, the interval N between the two ring grooves 45, 46 is opened to the width thickness of the final tightening ring 45, and the interval M between the temporary tightening ring groove 46 and the circumferential end face 47 of the annular outer tubular portion 41 opposite the annular outer tubular portion 43 is also opened to the width thickness of the final tightening link 6. The shape of the partition inner peripheral frame 48 that forms these two intervals N and M is a sliding inclined surface formed in a tapered shape that descends from the circumferential end face 47 toward the steel pipe pressing portion 43, making it easy to fit the final tightening ring 6 and the temporary tightening ring 7 from the circumferential end face 47 side into the final tightening ring groove 45 and the temporary tightening ring groove 46, respectively.

A part of the annular outer cylinder 41 is cut out to form an opening 49, which also cuts the main tightening ring groove 45 and the temporary tightening ring groove 46, and a peripheral wall 49a of the thickness of the annular outer cylinder 41 is exposed around the opening 49. 41a is a tool hole provided as necessary on the outer periphery of the annular outer cylinder 41, and is used as necessary when pressing the nut 4 onto the fitting 3.

As shown in FIG. 2, the main tightening ring 6 is a ring made of a resilient metal such as stainless steel of a predetermined thickness, and has a partially cut-out main tightening notch 62 and a hook 63 for gripping with a tool or the like formed at both opposing ends of the main tightening notch 62, and a provisional tightening projection 64 and a formal tightening projection 65 are provided on the outer periphery of the ring near the hook 63 in a raised manner. The hook 63 is provided so that it can abut against the peripheral wall 49a of the opening 49, and the provisional tightening projection 64 and the formal tightening projection 65 provided on the outer periphery of the ring near the hook 63 can also engage when the nearby hook 63 is not engaged with the peripheral wall 49a of the entrance to the formal tightening ring groove 45.

Five arc-shaped tightening vanes 66 are provided on the inner peripheral surface of the tightening ring 6 with a vane spacing 66a that allows the circumferential length L of the engagement vanes 32a to pass through, as shown in FIG. 7. The circumferential length of the tightening vanes 66 is a length that allows them to pass through the spacing K of the engagement vanes 32a. Furthermore, the length that protrudes from the inner peripheral surface toward the center is slightly longer than the protruding height H of the engagement vanes 66, so that when the inner peripheral surfaces of the five tightening vanes 66 are fitted into the outer peripheral surface of the connection tube 32 when the joint 3 and nut 4 are joined, they can pass through without being obstructed by the engagement vanes 32a.

The temporary fastening ring 7 is a ring made of a metal having elasticity such as stainless steel or a synthetic resin material, as shown in Fig. 2 , and has a temporary fastening notch 72 cut out from a part of the ring, and a locking head 73 is formed at both ends of the temporary fastening notch 72 that face each other. As shown in Fig. 3, the locking head 73 protrudes into the opening 49 of the annular outer cylinder 41 and abuts against the peripheral wall 49a at the entrance of the temporary fastening ring groove 7, so that the annular outer cylinder 41 rotates in the same direction at the same time when it rotates in either the left or right direction. If a bulge 74 is formed on the side of the locking head 73 , the gap distance between the locking head 73 and the final fastening ring 6 is reliably maintained even in the area of the opening 49 where the final fastening ring groove 45 and the temporary fastening ring groove 46 are not present. The temporary fastening ring 7 is not subjected to a force in the thickness direction (axial direction) of the ring except during temporary fastening, so it can withstand the strength of the synthetic resin material, and is useful because it is easier to mold than metal.

As shown in FIG. 2, four arc-shaped temporary tightening blades 76 are provided on the inner peripheral surface of the temporary tightening ring 7 with a blade interval 76a that allows the circumferential length L of the engagement blade 32a to pass through. The circumferential length of the temporary tightening blade 76 is also a length that allows it to pass through the interval K of the engagement blade 32a. Furthermore, the protruding length from the inner circumference toward the center is slightly longer than the protruding height H of the engagement blade 66, so that, like the final tightening blade 66, the four inner peripheral surfaces of the temporary tightening blade 76 can easily pass through without being obstructed by the engagement blade 32a when fitting them into the outer peripheral surface of the connection tube 32. The number of temporary tightening blades 76 is four, one less than the final tightening ring 66, because it is the final tightening blade 66 that actually connects and applies force, and the temporary tightening blade 76 is only used for temporary connection, so there is no problem if there are fewer of them.

As can be seen clearly in Figures 1 and 2, the cross-sectional shape of the annular packing 5 is approximately trapezoidal, and two sides that form approximately right angles are stored in the annular packing storage section 36a formed by the large expansion section 36 of the joint 2 and the difference wall surface 35a that is the step between this large expansion section 36 and the medium expansion section 35. The inclined surface that faces approximately at a right angle is formed with a small protrusion 5a as necessary, and when it abuts against the end side inclined surface 21a of the mountain-shaped protrusion 21 during connection, the volume shrinks together with the main body of the packing 5, increasing the abutment strength and preventing fluid leakage.

The mountain-shaped protrusion 21, consisting of the end side inclined surface 21a and the inner side inclined surface 21b, which are in two different directions at the end of the steel pipe 2, is formed using a pipe expansion machine 8 as shown in FIG. 17. In this pipe expansion machine 8, a pipe expansion head 81 and a driving source such as a driving piston (not shown) that pushes and pulls the connecting pipe 82 in the axial direction inside the pipe expansion head 81 are fixed to a mounting frame (not shown) so that they can be attached and detached. In the center of the pipe expansion head 81, an insertion hole 81a is provided for inserting the connecting rod 84 at the tip of the pressure rod 83, and a steel pipe insertion tube 81b is provided from the outer periphery of this insertion hole 81a in the opposite direction to the connecting pipe 82. And, a slope forming surface 81d is provided on the inner periphery of the tip of this steel pipe insertion tube 81b to form the end side inclined surface 21a of the mountain-shaped protrusion 21.

The tip of the connecting rod 84 is screwed to the connecting tube 82, so that the expansion rubber 85, which abuts against the step surface 83a caused by the difference in diameter between the connecting rod 84 and the pressure rod 83, and the guide ring 86, which abuts against the expansion rubber 85 and the end face 81c of the expansion head 81 in the circumferential direction of the insertion hole 81a, are each fitted movably onto the connecting rod 84. The annular outer tube 41 of the nut 4 is fitted onto the outer periphery of the steel pipe fitting tube 81b, so that the tip of the steel pipe fitting tube 81b abuts against the inner surface of the steel pipe pressing portion 43. A plurality of locking devices 87 that lock the steel pipe pressing portion 43 of the nut 4 so as not to move during expansion are provided on the end face 81c of the expansion guide 81 in a freely rotatable manner.

When expanding a steel pipe 2 using this pipe expansion machine 8 having the above configuration, as shown in FIG. 17, one end of the steel pipe 2 is inserted from the end of the pressure rod 83 so as to pass through the pipe insertion hole 42 of the nut 4, and pushed until it abuts against the front surface of the pipe expansion head 81. As a result, the end side of the steel pipe 2 abuts against the end face 81c of the pipe expansion head 81 and is locked, and the inner periphery of the tip is inserted into the outer periphery of the guide link 86 and the pipe expansion rubber 85. At this point, the locking tool 87 is rotated around the rotation axis 87a to abut against the outer surface of the steel pipe pressing part 43 and lock the nut 4 so that it does not move in the opposite direction to the pipe expansion head 81. After that, when the driving source not shown is operated and the pressure rod 83 is pulled toward the pipe expansion head 81, the pipe expansion rubber 85, which is prevented from moving toward the pipe expansion head 81 by the guide ring 86, is subjected to a force in the axial direction by the step surface 83a, and the contracted volume expands toward the outer periphery, expanding the diameter of the steel pipe 2. The outer periphery of the end of the steel pipe 2 has the inclined pressing surface 44 of the inclined pressing portion 43 of the nut 4 and the inclined forming surface 81d of the steel pipe fitting tube portion 81b, so that the outer periphery of the end of the steel pipe 2 forms a mountain-shaped protrusion 21 consisting of two end side inclined surfaces 21a and an inner side inclined surface 21b.

As shown in Figures 17 and 4, if the final tightening ring 6 and the provisional tightening ring 7 are fitted into the final tightening ring groove 45 and the provisional tightening ring groove 46 provided on the inner peripheral surface of the annular outer tube portion 41 of the nut 4 beforehand when expanding the tube with the tube expander 8, the work efficiency is improved compared to fitting them after the tube expansion.

When the mountain-shaped protrusion 21 is thus formed on the outer periphery of the end of the steel pipe 2, the locking device 87 is rotated around the rotation axis 87a to remove it from the steel pipe pressing surface 43, and the steel pipe 2 is pulled out from the pressure rod 83. The nut 4 can be used as it is, fitted onto the outer periphery of the end of the steel pipe 2.

It is also possible to form the mountain-shaped protrusion 21 using a tube expander of a type other than the tube expander 8 of this embodiment shown in Figure 17. However, using this tube expander 8 has the advantage that the inclined pressing surface 44 of the nut 4 and the inner inclined surface 21b of the mountain-shaped protrusion 21 of the steel pipe 2 coincide with each other, allowing for a connection with a high degree of adhesion.

Next, we will explain the connection procedure for the steel pipe and joint connection mechanism 1 configured as described above.

When constructing the connection mechanism 1 between the steel pipe and the joint at the construction site of the piping, it is performed in two steps, the temporary tightening work and the final tightening work, which will be described below . First, the temporary tightening work (step) will be described. As shown in FIG. 1, the end 2a is inserted into the medium expansion part 35 from the opening of the connection tubular part 32 of the joint 3, and the two protrusions 5a of the packing 5, which are previously fitted into the packing storage part 36a, are pressed against the end side inclined surface 21a and pushed in until they come into contact. As a result, the side and outer circumferential surface of the packing 5 are in close contact with the difference wall surface 35a and the inner circumferential surface of the large expansion part 36, respectively, so that airtightness is maintained and fluid leakage is blocked. The two end side inclined surfaces 21a and the inner side inclined surface 21b of the mountain-shaped protrusion 21 in different directions are pressed by the packing 5 of the packing storage part 36a of the joint 3 and the inclined pressing surface 46 of the nut 4 so as to be sandwiched from both directions, and are connected. When pressure exceeding the shrinkage limit of the material of the packing 5 is applied, the corner where the intermediate expansion portion 35 and the difference wall surface 35a intersect comes into contact with the end side inclined surface 21a, thereby protecting the packing 5.

When the end 2a of the steel pipe 2 is inserted into the pipe insertion hole 42 of the nut 4 used during pipe expansion by the pipe expansion machine 8, the inner inclined surface 21b of the mountain-shaped protrusion 21 abuts against the inclined pressing surface 44 of the steel pipe pressing portion 43, and the longitudinal direction of the straight portion of the steel pipe 2 extends outward from the pipe insertion hole 42.

Next, as shown clearly in Figure 4 , the final fastening ring 6 fitted into the final fastening ring groove 45 and the temporary fastening ring 7 fitted into the temporary fastening ring groove 46 are aligned in the following manner so that they overlap in the axial direction in a non-rotatable state within their respective grooves 45, 46.

Since both the final tightening ring 6 and the temporary tightening ring 7 are biased in the direction of opening the elastic rings, as shown in Fig. 2, the two locking heads 73 at both ends of the temporary tightening notch 72 are hooked on the peripheral walls 49a facing each other in the circumferential direction of the opening 49, and as shown in Figs. 3 and 4, the temporary tightening ring 7 is in a fixed position where it does not rotate in the circumferential direction within the temporary tightening ring groove 46. Then, as can be clearly seen in Fig. 8, when one of the hook portions 63 at both ends of the final tightening ring 6 is abutted against the peripheral wall 49a by the operator's hand or the like, the final tightening projection 65 in the vicinity of this one hook portion 63 sinks into the final tightening ring groove 45 against the biasing force in the expanding direction when the hook portion 63 approaches the peripheral wall 49a. As a result, the final fastening projection 64 exposed to the opening 49 near the other hook portion 63 is caught by the opposing peripheral wall 49a at the outlet of the final fastening ring groove 45 due to the outward spreading biasing force of the final fastening ring 6, preventing the final fastening ring 6 from rotating in the reverse direction. Ultimately, as shown in Figure 8, the final fastening ring 6 is unable to rotate in the final fastening ring groove 45, with the hook portion 63 and the final fastening projection 64 being engaged with the opposing peripheral wall 49a. In this state, as can be clearly seen in Figure 3, the final fastening blade 66 and the preliminary fastening blade 76 are aligned in the axial direction, and at the same time, the final fastening blade interval 66a and the preliminary fastening blade interval 76a also coincide in the axial direction and are opened in the axial direction.

(Preparation for tightening)
In this manner, with the final tightening ring 6 and the provisional tightening ring 7 in the final tightening ring groove 45 and the provisional tightening ring groove 46, respectively, unable to rotate, and with the final tightening blade 66 and the provisional tightening blade 76 overlapping with a gap in the axial direction, the joint 3 and the nut 4 are opposed to each other, and the connecting tubular portion 32 of the joint 3 is pushed into the inside of the annular outer tubular portion 41 of the nut 4, as shown in Fig. 6. This pushing is smooth, since the provisional tightening blade 76 and the tightening blade 66 overlapping with a gap K in the axial direction, which is spaced apart from each other, pass through the provisional tightening blade gap 76a and the final tightening blade gap 66a, which are spaced apart from each other in the axial direction. If there is a rotation stop rod 32b at this time, it will be guided by this to facilitate the provisional tightening blade 76 moving straight in the axial direction.

When pushed inward as described above , as shown in Figure 7, the pre-fastening blade 76 passes through the space K between the engagement blades 32 and stops just before the stop block 32c, and the final fastening blade 66, which overlaps with this pre-fastening blade 76 at a space in the axial direction, stops in a state where it has entered the engagement blade space K. This stopping occurs because the packing 5 inside the joint 3 abuts against the end side inclined surface 2a of the mountain-shaped projection 21, and the steel pipe pressing portion 43 of the nut 4 abuts against the inner side inclined surface 21b, so that the worker cannot push it in any further by hand.

(Temporary fastening work)
Next, the nut 4 is rotated forward in the direction of the arrow P in Fig. 9 to perform the temporary tightening operation (step) . As shown in Figs. 9 and 10, the locking head 73 of the temporary tightening ring 7 is hooked on the peripheral wall 49a, so the temporary tightening blade 76 rotates forward in the direction P together with the nut 4 and stops when the rotation of the nut 4 stops. At this point, as shown by the dotted line in Fig. 10, the temporary tightening blade 76 of the temporary tightening ring 7 is located above the connecting tube portion 32 between the side surface of the engagement blade 32a and the flange portion 33.

As shown in Figures 3 and 8, one of the hooks 63 of the final tightening ring 6 is not blocked by the peripheral wall 49a in the forward rotation direction, and the final tightening blade 66 is not blocked by the engagement blade 32a on the forward rotation direction side of the nut 4, so the other hook 63 rotates until it abuts against the peripheral wall 49a due to the forward rotation P of the nut 4. In this state, the temporary stop protrusion 65 near one of the hooks 63 comes out of the peripheral wall 49a and serves to prevent the reverse rotation of the final tightening ring 6. The forward rotation P of the final tightening ring 6 is blocked because the final tightening blade 66 is in the gap K and is sandwiched and abutted by the engagement blade 32a. In other words, the nut 4 is in a state where it cannot rotate forward or backward relative to the joint 3. This completes one temporary tightening operation . By repeating such operations, the steel pipes 2 are connected one after another to the joint 2 through the nut 4 , forming a piping network, and the temporary tightening operation is completed. The piping network here means a piping to which two or more steel pipes are connected .

In this way, since the nut 4 cannot rotate relative to the joint 3, and the temporary tightening ring 7 is located between the engagement blade 32a and the flange 33, even if tension or rotational force acts on the steel pipe 2 due to its own weight or vibration caused by the formation of a steel pipe network, the joint 3 and nut 4 will not loosen and the connection will not be released, and the temporary tightening blade 76 will be held between the flange 33 and the engagement blade 32a in the pulling or loosening direction of the piping network, so the connection will not come off. Moreover, since there is some play between the flange 33 and the engagement blade 32a to allow the temporary tightening blade 76 to move, it can also accommodate tension and loosening of the piping network.

When constructing a piping network, this type of temporary tightening work (process) can be performed by temporarily completing the entire piping network by suspending it near the construction site with wire or the like, and then performing the final tightening work described below, which can improve work efficiency and prevent construction errors such as forgetting to tighten.

(Final tightening work)
The final tightening operation (step) is performed by, after the provisional tightening state described above, further strongly approaching the joint 3 and the nut 4 in the directions of the opposing arrows T and T' in Fig. 16 , causing the final tightening vane 66 to escape from the gap K toward the flange 33, and then rotating only the final tightening ring 6 in the forward direction . This approaching is performed by attaching the end of a tightening tool (not shown) to the tool hole 41a of the nut 4 and the flange 33 of the joint 3 and tightening them. Then, due to this final tightening, the axial length of the packing 5 in contact with the end side inclined surface 21a is shortened and the loosened gap between the joint 3 and the nut 4 is closed, and the annular outer cylinder portion 41 approaches the joint 3 in the axial direction relatively by the length that has been shortened and the gap has disappeared. As a result, as shown in Figures 11 and 12, the pre-fastening blade 76 and the final fastening blade 66 both move simultaneously in the direction of arrow S, which is toward the flange portion 33, with the pre-fastening blade 76 moving between the stop base 32c and the rotation stop rod 32b, and the final fastening blade 66 moving in the circumferential direction along the rotation stop rod 32b between the stop base 32c and the engaging blade 32a.

Then, while maintaining this mutually approaching state, one of the hooks 63 that appears in the opening 49 and abuts against the peripheral wall 49a is rotated in the direction of the arrow P in Figures 13 and 14. If necessary, this reverse rotation is performed by using a tool not shown in the figure to rotate the other hook 63 until it abuts against the opposing peripheral wall 49a. Then, as shown in Figure 15, when the other hook 63 leaves the peripheral wall 49a, the nearby main fastening projection 64 comes out of the main fastening ring groove 46 and jumps outward by its own elastic force to be engaged with the peripheral wall 49a of the opening 49. At the same time, when the other hook 63 abuts against the peripheral wall 49a, the nearby temporary fastening projection 65 sinks into the main fastening ring groove 45, completing the main fastening operation. This is symmetrical to Figure 8 during the temporary fastening operation.

At this stage, as shown in Figures 13 and 14, the final tightening blade 66, i.e., the final tightening ring 6, is unable to rotate in either the forward or reverse direction, and is in a position where it is in close contact with the side of the flange 33 of the engagement blade 32a. As the final tightening operation is performed, the axial distance between the final tightening blade 66 and the engagement blade 36a narrows, which strengthens the degree of contact and increases the frictional force, further preventing rotation in the loosening direction. Note that even if the rotation of the final tightening ring 6 cannot be prevented by the final fastening projections 64 and temporary fastening projections 65, the hook portion 63 hits the peripheral wall 49a and prevents rotation, so it can still be used, although some loosening occurs.

In addition, both circumferential ends of the provisional tightening blade 76 are locked by the locking base 32c and the rotation locking rod 32b, and the locking heads 73 at both ends are prevented from rotating by the peripheral wall 49a of the opening 49, which also prevents the nut 4 from rotating in the loosening direction.

In addition, one of the hook portions 63 and the main stop projection 65 of the main tightening ring 6 abuts against the peripheral wall 49a of the opening 49, preventing the nut 4 from rotating in the loosening direction. In this way, the rotation of the joint 3 and the nut 4 in the loosening direction is prevented by the frictional force of the main tightening ring 6, the temporary tightening ring 7, and the main tightening blade 66 and the side of the engagement blade 32a caused by the action of the force in the tensile direction during piping, preventing loosening even after many years of use.

By carrying out the connection work in two stages, a temporary tightening work (process) and a final tightening work (process), it is possible to improve work efficiency and prevent forgetting to tighten by repeating the same work.

Industrial application fields

This invention uses a configuration in which a joint with a mountain-shaped protrusion at the end is clamped between the joint and a nut to connect and prevent loosening, making it particularly effective for use in piping in buildings where vibrations are likely to occur. In addition, since the connection work is performed through temporary tightening and final tightening, it is particularly useful for structures that have extensive piping networks.

1 Connection mechanism between steel pipe and joint 2 Steel pipe 2a End 21 Mountain-shaped protrusion 21a End side inclined surface 21b Inner side inclined surface 3 Joint 31 Connecting tube portion 32 Connection tube portion 32a Engagement blade 32b Rotation stop bar 32c Stop base 33 Flange portion 34 Fluid passage 35 Medium enlarged diameter portion 35a Differential wall portion 36 Large enlarged diameter portion 36a Packing storage portion 4 Nut 41 Annular outer tube portion 41a Tool hole 42 Pipe insertion hole 43 Steel pipe pressing portion 44 Inclined pressing surface 45 Final tightening ring groove 46 Pre-tightening ring groove 47 Circumferential end surface 48 Partition inner peripheral frame 49 Opening 49a Peripheral wall 5 Packing 5a Protrusion 6 Final tightening ring 61 Outer peripheral edge portion 62 Final tightening notch portion 63 Hook portion 64 Main locking protrusion (locking protrusion)
65 Temporary locking protrusion (locking protrusion)
66 Final tightening blade 66a Final tightening blade interval 7 Pre-tightening ring 71 Outer peripheral edge 72 Pre-tightening notch 73 Locking head 74 Bulged portion 76 Pre-tightening blade 76a Pre-tightening blade interval 8 Tube expansion machine 81 Tube expansion head 81a Insertion hole 81d Slope forming surface 82 Connecting tube 83 Pressurizing rod 84 Connecting rod 85 Tube expansion rubber 86 Guide link

Claims (7)

A connection mechanism between a steel pipe and a fitting, in which a steel pipe having a mountain-shaped protrusion on the end side is connected by sandwiching it between a fitting and a nut,
The joint has a medium expansion section on the inner periphery side of the connecting tubular section at the end of the connecting tubular section having a fluid passage therein, through which the outer periphery of the end side of the steel pipe is inserted, and further has a packing storage section which is a large expansion section with an even larger diameter than the medium expansion section and opens to the end, and has a flange section extending outward on the outer periphery near the boundary between the connecting tubular section and the connecting tubular section, and is provided with a plurality of engaging blades at a predetermined interval in the circumferential direction at the tip of the outer periphery of the connecting tubular section, and a plurality of stoppers are provided at a predetermined interval in the axial direction from the engaging blades and located between the width direction of the intervals of the engaging blades spaced in the circumferential direction of the engaging blades,
The nut has an annular outer tubular portion that fits onto the outer periphery of the engaging blade of the connecting tubular portion, and a steel pipe pressing portion that forms a pipe insertion hole in the center at one end side of the annular outer tubular portion, through which the steel pipe is inserted, and is equipped with an inclined pressing surface that presses the inner inclined surface of the mountain-shaped protrusion of the steel pipe, and on the inner periphery of the annular outer tubular portion, a final fastening ring and a temporary fastening ring are provided, in order from the side closest to the inclined pressing surface , at a predetermined interval in the axial direction so as to be inseparable from each other and to be freely rotatable in the circumferential direction, the temporary fastening ring is arranged rotatably together with the annular outer tubular portion, while the final fastening ring is capable of rotating independently by a predetermined angle, and on the inner periphery of the final fastening ring and the temporary fastening ring, final fastening blades and temporary fastening blades having a predetermined circumferential length and a predetermined protruding height toward the center are provided at an interval equivalent to or greater than the circumferential length of the engaging blade,
The end side of the steel pipe inserted into the pipe insertion hole of the nut is inserted into the connection tube portion, and the packing stored in the packing storage portion is used to press the end side inclined surface of the mountain-shaped protrusion, and the inclined pressing surface is used to press the inner side inclined surface of the mountain-shaped protrusion, so that the temporary fastening blade of the temporary fastening ring abuts against the stop block and is locked so as not to move in the axial direction, and the main fastening blade is sandwiched between the engagement blades and cannot rotate, and the temporary fastening blade is moved by the rotation of the nut. A connection mechanism for a steel pipe and a fitting, characterized in that a temporary tightening is performed in which the gasket is positioned on the side of the engaging blade to prevent movement in the removal direction, and then the gap between the nut and the fitting is further tightened to reduce the packing, and the final tightening ring is rotated, and final tightening is performed to position the final tightening blade on the side of the engaging blade in a state where it cannot move, thereby connecting and fixing the fitting and the nut in a mutually non-rotatable state while preventing the force in the removal direction from the annular outer tubular portion to the connecting tubular portion. The connection mechanism for a steel pipe and a joint as described in claim 1, characterized in that the structure in which the main tightening ring and the temporary tightening ring are arranged on the inner circumference of the annular outer cylinder at a predetermined interval in the axial direction so that they cannot move away from each other and can rotate freely in the circumferential direction is a structure in which the outer circumferences of the main tightening ring groove and the temporary tightening ring groove arranged at a predetermined interval in the axial direction are fitted rotatably into each other. The connection mechanism for a steel pipe and a joint according to claim 1 or 2, characterized in that the main tightening ring and the temporary tightening ring are elastic rings each having a hook or a locking head at both ends of a cutout portion of the ring. The connection mechanism for a steel pipe and a joint as described in claim 2, characterized in that the main tightening ring is made of a metal material and the temporary tightening ring is made of a synthetic resin material. The connection mechanism for a steel pipe and a joint as described in claim 1, characterized in that a rotation stop bar is provided to provide a predetermined distance in the axial direction between the stop base and the engagement blade interval. 4. A connection mechanism for a steel pipe and a joint according to claim 3 , characterized in that the locking heads provided at both ends of the notch of the temporary tightening ring have bulges in the direction of the final tightening ring. 4. A connection mechanism for a steel pipe and a joint according to claim 3 , characterized in that a locking projection is provided on the outer periphery in the vicinity of the hook portion provided at both ends of the notch of the tightening ring.

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