JP4358812B2 - Self-balancing type pull-out prevention device for pipe joints. - Google Patents

Description

  In the present invention, a plurality of rigid members that can bite into the outer surface of the tube body and the inner surface of the joint are arranged substantially evenly in the circumferential direction in a space having a wedge-shaped cross section formed by the outer surface of the cylindrical tube body and the inner surface of the conical joint. The present invention relates to a self-balancing type pull-out prevention device for a pipe joint having the above-described configuration.

  For example, in a pipe joint device for a drain pipe used in a building drainage system, a gripping member shown in Japanese Utility Model Publication No. 7-19690, or a first method for gripping a pipe body with rubber packing The second method of gripping the pipe body by the above method and connecting it to the joint, or a rigid sphere is arranged in the rubber packing between the flange of the joint and the pipe body as shown in Utility Model Registration No. 3099370, There is a third method in which when a pulling force is applied to the body, a rigid sphere is pressed against the surface of the tube to exert a retaining force. In these joint devices, a constant gripping force is applied to the outer surface of the tube body by a rubber packing, a grip member, a metal ball, or the like, and an effect to counter the pulling force of the tube body is generated by the maximum static friction force.

  More specifically, referring to FIGS. 13 and 14, the first method is to tighten the annular rubber packing to the outer surface of the tube by the joint body and the flange to generate the gripping force R <b> 1. Is to tighten and grip firmly (gripping force R2) using a grip member surrounding the tube in order to further increase the gripping force of the first method. The third method is to insert several rigid spheres between the rubber packing and the flange in the first method, and when the joint body and flange are tightened with bolts and nuts, the rigid sphere becomes the flange and rubber packing. It bites into the surface of the tubular body by the pressure of and exerts a gripping force R3.

  Considering the mechanical condition of tube disconnection in the conventional joint device, the frictional force f is generated in proportion to the applied force R such as the gripping forces R1 to R3 applied as vertical pressure to the outer surface of the tube, and its proportionality constant. μ is defined as the coefficient of friction. When a pulling force F is applied to the tubular body and f = μR <F, the tubular body moves in the removal direction by Δl. FIG. 15 shows an actual measurement value of the amount Lmm of the tubular body coming out of the joint device when the tubular body having a diameter of 4 inches is pulled with an external force F Newton.

  1) As shown in FIG. 15, even if the external force F increases, the displacement L is moved by a minute Δl. This indicates that μ is the maximum coefficient of static friction. As the tube starts to move, μ changes to a dynamic friction coefficient, and the increase in the amount of slipping out increases and eventually falls off.

  2) The friction coefficient μ varies depending on the surface condition of the tube body and rubber packing, or the pressure R also varies depending on the tightening force of the bolt and nut between the joint body and the flange, so the friction force f = μR is also Moreover, it fluctuates, and the pull-out force varies greatly depending on the product as shown in FIG.

  3) In the conventional joint device, the mechanism that exerts the pull-out resistance depends on the gripping force applied to the pipe body by the rubber packing, so that the deterioration or alteration of the rubber directly affects the performance of the joint device (pipe Does not fall off, does not leak water). Therefore, it is difficult to maintain reliability over a long period of time.

ACT 7-19690 Utility model registration No. 3099370

  The present invention has been made paying attention to the above points, and an object of the present invention is to provide a self-balancing type pull-out preventing device in which a pull-out force acting on a pipe body is fed back to a gripping force in a pipe joint. Another object of the present invention is to provide a self-balancing type pull-out prevention device for a pipe joint that holds a pipe body until it is broken.

  In order to solve the above-described problems, the present invention provides a rigid member capable of causing biting on the outer surface of the tube body and the inner surface of the joint in a space having a wedge-shaped cross section formed by the outer surface of the cylindrical tube body and the inner surface of the conical joint. The rigid member is rotated around the axis in the circumferential direction of the tube and can move in the withdrawal direction when an external force in the direction of pulling out the tube and the joint is applied. As a condition for forming the body and causing the rigid member to rotate by the external force in the pulling-out direction, the included angle 2α formed by the outer surface of the tubular body and the inner surface of the joint in a space having a wedge-shaped cross-section is set to 17 ° ± 7 °, and Means is provided to configure the outer diameter of the rigid member to be at least twice the minimum gap Δg between the outer surface of the tube and the inner surface of the joint.

Principle of the Invention In the conventional pipe joint device, the pressing force R applied to the pipe body such as the gripping forces R1 to R3 shown in FIG. 14 is constant, and therefore the frictional force f against the pulling force F is also constant. The present invention is realized by the operating principle of a self-balancing type gripping force system in which a pulling force F is applied to a pipe body, and when the force increases, the frictional force f increases in proportion to the F. And

  According to the present invention, the amount of pull-out when the pipe is pulled by an external force is a fraction to 1/10 or less than that of a conventional pipe joint device, and the pipe body is dropped to the fracture limit of the joint body. It is possible to provide a revolutionary new joint device. Note that the pulling force on the pipe body is not only applied from the outside of the pipe body but also generated by the water pressure in the pipe or the pulsation of the water pressure in the drainage piping system.

  The present invention is illustrated in FIGS. The joint body may be the same as the conventional device. A wedge-shaped space that forms a wedge-shaped cross section ABC is formed by the cylindrical shape of the outer surface of the tube body and the conical shape of the inner surface of the flange. A plurality of rigid members made of a spherical rotating body or a cylindrical rotating body unified with a radius r are arranged so as to be arranged. At this time, it is assumed that the cross-sectional angle ∠ ABC = 2α, and the gap between the tube body and the flange is maintained at Δg along the tube body.

In FIG. 4, when a pulling force ΔF is applied in the length direction of the tubular body, the rotational torque determined by the respective friction coefficients μ1 and μ2 is applied to the rigid member composed of the rotating body sandwiched between the tubular body and the flange. P is generated and moves by Δl in the same direction as the extraction force ΔF (similar to the roller principle). When the center O of the rigid member moves to O ′, Δr = Δlsinα of the radius of the rigid member bites into the outer surface of the cylindrical tube body and the inner surface of the conical flange, and the increment of the pressure R is applied to each surface. ΔR is generated. This is as if the wedge is driven with a force ΔK into the space ABC having a wedge-shaped cross section, between the increase ΔR of the pressing force,
ΔK = 2ΔR (sin α + μ cos α)
Is the same as In the case of the present invention, the force ΔK is not directly applied to the rigid member, but the rigid body made of a rotating body inside the space having a wedge-shaped cross section by the rotational torque of the rigid member made of the rotating body generated by the pulling force ΔF applied to the tube. This is because the member moves and can be regarded as equivalent to being driven.

That is, if a and b are constants,
Δl = aΔF (1)
ΔR = bΔr = bΔlsin α (2)
Therefore, ΔR / ΔF = absin α = constant (3)
That is, when pulling force F is generated in the tube, generated pressing force R as a gripping force by the force, in proportion to the increment [Delta] F of the pull-out force (in equilibrium in [Delta] F) the gripping force of the pressure R An increment ΔR occurs. It is assumed that the desired gripping force R1 applied by the rubber packing has already been applied.

  In the apparatus of the present invention, the pulling force F is fed back as a gripping force R to a rigid member made of a rotating body by the mechanism described in detail above. Has a so-called self-balancing mechanism that requires a larger force F, so that the tube can be prevented from coming out, and the tube can be held until it breaks. Play.

  Hereinafter, the present invention will be described in more detail with reference to the drawings. 1 to 6 show an example of a self-balancing type pull-out preventing device 10 in a pipe joint according to the present invention. Reference numeral 11 denotes a pipe body, 12 denotes an outer surface thereof, 13 denotes a joint, and the main body 14 and the flange 15 are connected to each other. The rubber packing 17 inserted between the flange 16 and the flange 15 of the main body 14 can be strongly tightened by fastening bolts 18 and nuts 19 attached to both flanges 15 and 16. Reference numeral 14a denotes an inclined inner surface on the joint body side, and 17a denotes a locking end portion of the rubber packing.

  The cylindrical shape of the outer surface 12 of the tube 11 and the conical shape formed on the inner surface 12 of the flange 15 of the joint 13 constitute a space 20 having a wedge-shaped cross section ABC. The rubber packing 17 has a tapered holding portion 22 that enters the space 20 between the outer surface 12 of the tube body and the inner surface 21 of the joint, and a plurality of rigid members 23 made of a rotating body are provided in the circumferential direction. Are arranged almost evenly. The holding portion 22 has a thin portion 22 a and is provided so as to be able to move to some extent from the main body portion of the packing 17.

  3, 4, and 5, point A is a point on the joint inner surface 21, point B is an intersection of the extension line of the joint inner surface 21 and the tube outer surface 12, and point C is a point on the tube outer surface 12, All the points A, B, C are on the same plane in the radial direction passing through the center of the tube 11. Further, r is the radius of the rigid member 23 which is a rotating body, and Δg is the minimum gap between the pipe outer surface 12 and the joint inner surface 21. FIG. 5 schematically shows the relationship between the wedge-shaped space 20 formed by the tube outer surface 12 and the joint inner surface 21 and the spherical rigid member 23 arranged there.

Example 1 (see FIGS. 1 to 6)
This embodiment is a self-balancing type pull-out prevention device for pipe joints, which is applied to a nominal 4-inch pipe. The main body 14 and the flange 15 of the joint 13 are made of cast iron, and the pipe body 11 used is a carbon steel pipe (SGP) for piping. The steel body member 23 made of a rotating body is selected according to the mode of the tubular body 11 to be used. In the case of the tube body 11 made of SGP, there is a rust-proof zinc plating on the surface, and the rolling friction coefficient μ2 is relatively large, so the rigid member 23 made of a rotating body is a steel sphere.

  The included angle of the wedge-shaped space 20 constituted by the tubular body outer surface 12 and the flange portion inner surface 21 was 2α = 17 degrees, and the radius of the rigid member 23 made of a steel ball was r = 2.4 mm. FIG. 6 shows an actual measurement value of the tube pull-out length (mm) with respect to the tube pull-out force F (Newton) when the number of steel balls is changed. In addition, the measured values of the conventional product under the same conditions are also shown.

  When the number of steel balls is 3, 4 and 6, in the graph, the data stops when the amount of withdrawal is about 15 mm. The steel ball, which is the rigid member 23, is interlocked with the withdrawal of the tubular body 11. It indicates that it has been rotated and finally dropped from the flange. Further, in the case of 12 steel balls of the example, the fact that the slip-out amount does not reach the vicinity of 15 mm and ends at 12.5 mm indicates that the joint device body was broken at 60000N. The following can be said from this graph.

  1) Compared with the conventional product, the device according to the present invention equipped with 12 steel balls has a proof strength of 5 times or more with respect to the pulling-out force of the tube, and has been improved dramatically. The pipe body did not fall off at 60000N, but the casting destruction of the joint device itself occurred, which indicates that the joint gripping mechanism was still operating.

2) The measured values in Example 1 indicate that the tube removal amount L is substantially a straight line with respect to the tube pull-out force F, that is, ΔF / Δl = constant indicates that the equation (1) holds. Furthermore, if the resistance to F against minute displacement per steel ball is ΔP,
ΔP = ΔF / Δl · n (4)
Where n is the number of steel balls

  As shown in Table 1, ΔP is constant at about 220 Newtons / mm, and the formula (3) is satisfied, that is, the steel ball rotates in the wedge-shaped space, which corresponds to an increase in the amount F of the tubular body. It shows that the drag force (P: proportional to R) increases in a self-equilibrium manner.

  3) The drag increases with the number of steel balls because the load is distributed on the tube and the flange. When the number of steel balls is too small, the tube body is dented by the load R along with the rotation of the steel balls, and finally the tube is removed while breaking the flange edge. By increasing the number of steel balls, the load R is distributed on the tube, and can withstand loads exceeding the fracture limit of the joint casting. These can be easily understood from a rule of thumb.

Example 2
When the pipe body 24 to be connected is hard vinyl chloride (VP), the surface of the pipe body is very smooth and easily deformed, so a gear-shaped cylindrical part is suitable as a rigid member (FIGS. 9A and 9B). When the size of the tube body 24 is 4 inches as in the above examples, the rigid member 25 made of 12 cylindrical parts is provided evenly on the flange side outer edge portion of the rubber packing 26 as shown in FIGS. 8A and 8B. Insert into the recess 27. The number of rigid members 25 is appropriate for pipes of other sizes, typically 4 inch pipes.

  The principle is the same as in the case of the rigid member 25 made of a steel ball. By pulling out the VP tubular body 24, the teeth of the rigid member 25 bite into the surface of the VP tubular body 24 to ensure the rotational torque. It moves in the wedge-shaped space 20 toward the flange edge 28. Thus, the gripping force increases. In addition, since it may be the same as that of the former thing about the structure other than the code | symbol newly shown here, a code | symbol is used and detailed description is not repeated. FIG. 12 shows measured values of the amount of the VP tubular body 24 with respect to the pulling force F of the second embodiment. From FIG. 12, it can be understood that the conventional joint has a markedly improved resistance. Moreover, since the pitch of the teeth of the rigid member 25 made of a gear-shaped cylindrical part surely leaves a trace on the surface of the VP pipe body 24 after the experiment, it can be seen that the VP pipe body 24 rotates according to theory.

Conditions required for the establishment of the present invention 1) Rotational radius r and included angle α of a rigid member as a rotating body
In FIG. 4, Δg gaps are evenly provided between the tube and the flange. As an example, the outer dimension Фp of the 4-inch carbon steel pipe and the inner diameter Фf of the flange are respectively
Фp = 114.3 ± 0.8mm
Фf = 117.4 ± 0.5mm
Therefore, the maximum Δg = 1/2 × {maximum Фf−minimum Фp} = 1/2 × 4.4 mm.

By the way, when the pulling force is applied to the tube body, it is not uniform, and the actual state is that the tube body is swung vertically and horizontally. Therefore, the maximum gap to be considered is the case where one side is zero mm and the other is the maximum Δg × 2 = 4.4 mm. Even in this case, the rigid members 23 and 25 which are rotating bodies should not fall off. That is,
2r> maximum Δg × 2 (= 4.4 mm) (5)
is required. In the case where the rigid member is the steel ball of Example 1 described above, 2r = 4.8 mm, and in the case of the gear-shaped cylindrical part of Example 2, the gear core diameter 2r ′ shown in FIG. 5) The condition of the formula is satisfied.

In the wedge space ABC containing the rigid members 23 and 25 which are rotating bodies satisfying the expression (5), the length AB ′ of the inner surface of the flange shown in FIG.
AB′≈r + (2r−Δg) / sin2α
That is, sin2α = (2r−Δg) / (AB′−r) (6)
If the included angle α is reduced, AB ′ becomes longer and the flange becomes larger. Therefore, in order to reduce the weight and size of the joint device, it is necessary to put AB ′ within a specified value. The smaller the radius of the rigid members 23 and 25, the larger the amount of movement due to rotation, and the more likely the biting occurs.

For a 4 inch tube,
Standard Δg = (117.4-114.3) /2=3.1 mm
When AB ′ is 15 and 20 mm, the formula (6) and the included angle 2α are obtained as shown in the following table for each of Examples 1 and 2. However, when the rotating body is a rigid member made of a gear-shaped cylindrical part, the radius r of the gear circumscribed circle (refer to 5.5 mm, 9A in this case) is used.

The minimum value of the included angle 2α is given by equation (6). On the other hand, if AB ′ is further shortened, the included angle is widened. If 2α ≧ 28 degrees, the rotating body idles and ΔR does not occur.

From the experimental results, it is practical
2α = 17 degrees ± 7 degrees (7)
It is desirable to be in This is a case of a 4-inch pipe, but it has been confirmed that the value of the expression (7) does not change greatly even if the pipe diameters are different.

2) Holding Mechanism of Rigid Member that is Rotating Body Considering the holding mechanism in the case where the rigid member that is a rotating body is a steel ball with reference to FIG. 3, a steel ball insertion hole 29 smaller than the steel ball diameter 2r is formed in the rubber packing 17. 12 are formed in advance in the circumferential direction by simultaneous molding, and when a steel ball is inserted, it is self-held by the elasticity of rubber. The thickness of the rubber packing in this portion is made thinner than the diameter of the rigid member 23 made of a steel ball, and the steel ball rotates in contact with the tube 11 and the flange 15 with certainty.

  Considering the holding mechanism in the case where the rigid member, which is also a rotating body, is a gear-shaped cylindrical part with reference to FIG. 7, a central hole 25a is provided in the gear-shaped cylindrical part, and it is supported by the support shaft 30 and rotated. As shown, a rigid member 25 composed of 12 gear-shaped cylindrical parts is connected by a single circular support shaft 30. As shown in FIG. 10B, twelve concave portions 27 for inserting the rigid member 25 made of a gear-shaped cylindrical part are provided on the outer edge of the tube body 24 and the rubber packing 26 in the wedge-shaped space 20 equally on the outer edge circumference. Actually, the interval between the members decreases as the rigid member 25 made of a gear-shaped cylindrical part rotates. Therefore, when the ring connection is made as shown in FIG. 8B, a part of the support shaft 30 is opened. .

3) About the shape of the rigid members 23 and 25 which are rotating bodies The rigid members 23 and 25 which are rotating bodies in the present invention include all those satisfying the following two requirements, whether spherical or cylindrical. That is,
a. Rotating in the direction of pulling out the tubular body 11,
b. A structure and a surface treatment that increase both the coefficient of friction μ1 between the rigid members 23 and 25, which are rotating bodies, and the tube 11, and the coefficient of friction μ2 between the flanges;
It is.

  In the case of a spherical shape, the surface of the rigid member provided with micron-level fine irregularities (so-called roughened surface) is also effective. In addition, it is also effective to arrange a large number of protrusions (conical shapes) on the surface of a steel ball uniformly like a confetti (however, the protrusion height is preferably ¼ or less of the sphere diameter). In the case of a cylindrical shape, those having a rough surface of a rigid member and a sawtooth gear structure are also effective.

  From the above description, the requirements necessary for the self-balancing type pull-out preventing device in the pipe joint of the present invention are as follows. As described in claim 1, a wedge-shaped cross section comprising a cylindrical tubular body outer surface and a conical joint inner surface is provided. The rigid member disposed in the shape space is rotated by the pulling force acting on the tube, the included angle 2α formed by the outer surface of the tube and the inner surface of the joint is 17 ° ± 7 °, and the outer diameter of the rigid member Is at least twice the minimum gap Δg between the tube outer surface and the joint inner surface. By being an invention that satisfies these requirements, the rigid body member slides due to the pulling force, and the device of the present invention does not depilate until it breaks away from the conventional device in which the dynamic friction coefficient dominates. The purpose and effect can be realized.

  In the description of the present invention, the size of the tube is a 4-inch tube because the 4-inch tube is representative of this type of tube. It is understood by those skilled in the art that a 4 inch tube can be handled as a representative from a 1 inch half tube to a 10 inch tube without any problem. Thus, it is clear that the apparatus of the present invention applies for at least 1 inch and a half to a 10 inch tube.

BRIEF DESCRIPTION OF THE DRAWINGS The longitudinal cross-sectional view which shows the whole self-balancing type | mold extraction prevention apparatus in the pipe joint which concerns on this invention. The perspective view which shows an example of the packing of Example 1 used for the apparatus of FIG. The principal part expanded sectional view of the apparatus of FIG. Explanatory drawing for analyzing the mechanical mechanism of the apparatus which concerns on this invention. The perspective view which shows typically the state which has arrange | positioned the spherical body which is a rigid member in the conical space between a pipe body outer surface and a coupling inner surface. The graph which shows the number of steel balls and displacement in Example 1 of this invention. The longitudinal cross-sectional view which shows the principal part of the apparatus of Example 2 of this invention. FIGS. 8A and 8B show an example of packing of Example 2 used in the apparatus of FIG. 7, wherein A is a perspective view, and B is a front view showing an example of a rigid member arranged in the packing. The rigid member used for the apparatus of FIG. 7 is shown, A is a perspective view of the type which is not supported by a spindle, B is a perspective view of the type supported by a spindle. 9B shows a state where the rigid body member of FIG. 9B is attached to the packing, A is a sectional view in the front direction, and B is a sectional view in the side direction. FIG. 6 is a perspective view showing a retaining mark by the apparatus according to the second embodiment. The graph which shows the effect of the thing of Example 2 of this invention. The front view which shows the effect | action of the conventional retaining device. FIG. 14 is a longitudinal sectional view showing the operation of the same device as FIG. 13. The graph which shows the effect by the device of Drawing 13 and Drawing 14.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Self-balancing type pull-out prevention apparatus 11 and 24 pipe body 12 Pipe outer surface 13 Joint 14 Main body 15 Flange 16 Main body flange 17, 26 Packing 18 Bolt 19 Nut 20 Wedge-shaped space 21 Joint inner surface 23 Rigid body Sphere or steel ball as a member 25 Gear-shaped cylindrical part as a rigid member 26 Connecting member 27 Recessed portion 28 Flange edge 29 Steel ball insertion hole

Claims (3)

A plurality of rigid members that can bite into the outer surface of the tube body and the inner surface of the joint are arranged substantially uniformly in the circumferential direction in a wedge-shaped cross-sectional space formed by the outer surface of the cylindrical tube body and the inner surface of the conical joint. The rigid member is formed into a rotating body that rotates about the axis in the circumferential direction of the tube and moves in the pulling direction when an external force in the direction of pulling out the tube and the joint is applied. As a condition for causing the member to rotate, the included angle 2α formed by the outer surface of the tube and the inner surface of the joint in a wedge-shaped cross-sectional space is set to 17 ° ± 7 °, and the outer diameter of the rigid member is set to the outer surface of the tube and the inner surface of the joint. Self-equilibrium type pull-out prevention device for pipe joints, characterized in that the minimum gap Δg is 2 times or more. 2. The self-balancing type pull-out prevention device for a pipe joint according to claim 1, wherein 12 rigid members are arranged at equal intervals in the circumferential direction of the pipe body. 3. The self-balancing type pull-out prevention device for a pipe joint according to claim 1, wherein the rigid member is a sphere, a cylinder, or a gear-shaped cylindrical part.

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