JP3138926B2 - Corrosion protection core for pipe fittings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe joint for a cast iron pipe which is buried underground to form a pipe for water supply, and more particularly to a dimensional adjustment at the time of site construction than a connection between standard cast iron pipes. The present invention relates to an anticorrosion core of a joint including a cut pipe generated when a cast iron pipe is cut in the middle.

[0002]

2. Description of the Related Art Cast iron pipes are provided with an anticorrosion function entirely by coating the outer surface and inner lining, and are laid underground and surrounded by moisture and other corrosive atmospheres contained in earth and sand that are in contact with the outer peripheral surface of the pipe. Even in contact with running water, it is protected so that corrosion does not easily progress. Therefore, as in the case of normal laying work, if the insertion port of another cast iron pipe is inserted into the socket of the cast iron pipe, and it is connected to each other in a water-sealed state with appropriate waterproof There is no opportunity for complete ingress of moisture and no concerns are raised in delivering good quality drinking water to consumers.

[0003] However, the laying of pipes does not always end only with the joining of cast iron pipes of fixed dimensions. In most laying works, it is rare that the last joint point of the section ends with a fixed size of the cast iron pipe, and the work area that was cut halfway to the specified length was completed by the cast iron pipe Is the normal mode. In most cases, pipes are usually excavated and laid underground along roads above ground, but roads do not always run straight,
Since it is far more common to travel along curved roads on old roads, the pipes for tap water and gas laid under the ground have to follow these, forming curved pipes. for that reason,
There is also a high need to follow the direction change of the pipeline by interposing a curved pipe instead of a straight pipe on the way.

[0004] The cut pipe cut on site on the way due to the construction is exposed to the corrosive atmosphere when the anticorrosive paint and the like applied to the inner and outer surfaces of the cut pipe are exfoliated, and when exposed to a corrosive atmosphere, the pipe surface is exposed. Is a weak point subject to intensive corrosive action. Regardless of how the other surfaces are protected by the anticorrosion function, if there is a weak point to which the metal surface is exposed even in one place, the corrosion protection as a whole is completely lost, corrosion concentrates, and rusting parts are rapidly formed. There is a high concern that the water in the pipe will be polluted in red as a defect that swells like a nodule and that the red water will be delivered to the home. Such a concern is difficult to wipe out even if the mating partner is a regular cast iron pipe socket or a curved pipe interposed in a bent portion.

[0005] In order to ensure waterproofness of a joint portion of a cast iron pipe including a cut pipe, several conventional techniques have been proposed. FIG. 4 shows an anticorrosive paint 10 for repairing an end face where the anticorrosive paint 101 is missing due to a cut 12a of the cut tube 1a being cut from the middle.
2 shows an example in which the anti-corrosion function was recovered by locally reapplying the surface near the cut in order to regenerate the anti-corrosion function locally lost by cutting. FIG. 5 shows the rust prevention cover 1 made of resin on the cut end 12b of the cut cut tube 1b.
03 is an example in which the surface of the exposed cast iron was covered with an affixed No. 03 to recover the anticorrosion function.

FIG. 6A and FIG.
In the prior art presented in Japanese Patent Publication No. 5 (1994), the pipe to be connected is a socket having a standard shape as can be seen from FIG. It is assumed that they will be joined. The target pipe 1
The cylindrical member 104 having a diameter slightly smaller than the inner diameter of the seal member 105 is formed of an elastic rubber material provided with a plurality of circumferentially continuous annular fins at regular intervals in the axial direction.
The gist of the present invention is a composite layer in which a metal cylinder 107 having an incision 106 continuous in the axial direction is coaxially and integrally fitted on the inner surface of the.
Due to the elastic deformation of the flexible sealing member 105 and the deformation allowed by the incision 106 cut into the metal cylinder 107 supporting the back, the variation in the inner diameter due to the tolerance of the pipe is absorbed, and the strength of the rubber material is improved. An important weakness is the idea of complementing the strength of the metal tube fitted behind.

[0007] In the invention of this figure, it can be interpreted that there is a gist in absorbing the fluctuation of the inner diameter of the pipe recognized as a tolerance due to the deformation starting from the incision cut in the metal cylinder.
In addition, instead of cutting the incision into the metal cylinder while standing in the same basic configuration, a rubber material is formed in such a manner that only the annular fin provided at the outermost end is inclined inwardly and the rubber material is formed.
No. 6194, Japanese Utility Model Laid-Open No. 5-36195, in which the outer diameters of the tip ends of a plurality of annular fins are set to be smaller toward the outer end, or Japanese Utility Model Application Publication No. JP-A-5-36195 in which the annular fins are spirally wound around the outer peripheral surface of a cylindrical body. No. 5-36196, etc., all of which fit a cylindrical body with a flexible annular fin having rubber elasticity onto the outer peripheral surface of a metal cylinder, and smoothly enter the cast iron pipe with a relatively light force. It can be said that it is a series of common techniques in that it can be mounted and forms an integral joint.

[0008]

Among the prior arts exemplified here, in the case of FIG. 4, repainting is performed on site, but the preparation and application of the coating material are not performed by a coating expert. However, there is no shortage of concerns about workability and the quality of the painted surface. In addition, since the construction may be a pipe laying construction in a cold region or in a severe winter, it is not unusual that a long time is required for drying after painting and the workability is reduced. In addition, there is a possibility that the inspection after construction may be insufficient in the field work, so the overcoating may be overlooked, or the anticorrosion function that was applied because the coating film is not suitable may not be fully exhibited, and local development There is also concern about rusting. In addition, in the case of repair work, not new pipe work, running water is constantly flowing out of the pipeline, so there is no opportunity to apply paint. It is a fatal obstacle that construction must be interrupted.

Similarly, with regard to the countermeasure of FIG. 5, the method of covering the surface by attaching a covering cover on the inside and outside of the cut pipe under construction at the site, although it seems reasonable from a theoretical point of view, is not realistic. It is difficult to give a very high evaluation from the viewpoint of workability and the reliability of the function after coating. In particular, in the process of winding a thin coating film by hand, superiority is likely to appear in the maintenance of functions due to differences in personal skills of workers, and there is a concern that maintaining complete anticorrosion properties remains uncertain. In addition, the end face of the cut tube corresponds to the opening at the time of pipe splicing and is inserted into the receptacle of the adjacent tube, but winding the coating film on the inner and outer surfaces is thin as the cut, Meaning that the outer diameter is large, and also because the winding by hand as described above does not necessarily form a uniform surface such as wrinkles on the surface or overlapping and folding the odd parts,
There is a drawback that it is easy to make the cause of difficulty in inserting the cut into the receptacle.

The prior art shown in FIG. 6 is a system in which a tubular body 104 that straddles in common between a cutting pipe and a receiving port is inserted, and compared with the conventional manual repainting or winding of a coating material. However, it is recognized that individual differences among workers are not affected and are effective in improving reliability. However, the cylindrical body 104 is all formed of a composite layer in which a metal cylinder 107 and an elastic seal member 105 are overlapped, and the support of the metal cylinder is an essential requirement for reinforcing the non-force of the rubber material. I have. In the case of forming a normal conduit, it is sufficient to have flexibility enough to absorb variations in the inner diameter of the pipe caused by tolerances allowed in the insertion port (cut section of the cut pipe). Not only a straight line but also a bent construction section is frequently encountered, and the function of maintaining the shape reinforced by metal may rather cause the construction to be performed under particularly difficult conditions. Naturally, with this configuration, it is almost impossible to join the cut pipe at the bent portion of the pipe line using a straight bent pipe or a bent pipe (bend pipe).

In many cases, a method of laying a pipeline employs a system called knotting piping (generally referred to as "separation piping"), in which the construction is simultaneously advanced from both sides and the end faces from both sides are joined on the way. When adopting this construction method, once insert the entire anticorrosion core into one of the cast iron pipes, suspend the cast iron pipe to be spliced, align the pipe axes, and then pull out the anticorrosion core. It is necessary to perform a procedure of inserting approximately half into the counterpart tube. However, this prior art seems to be intended only for the regular receiving / inserting method, and as far as the figures showing the embodiment are concerned, the conditions of the knotting pipe are not assumed, and The procedure in which the protruding annular fin 108 becomes a resistor and temporarily retracts into the mating tube becomes impossible.

[0012] The application of the metal cylinder 107 inside this prior art is also severely restricted in terms of anticorrosion ability. That is, since the pipe water flows down directly on the inner surface of the metal cylinder, if the metal cylinder rusts, red water is immediately generated and the polluted water is sent to households or the like. The only way to prevent this problem is to make the metal cylinder made of stainless steel, which is unlikely to rust, or to apply an anticorrosive paint to the surface of the steel material in the same way as a cast iron pipe. Is not good, and there is a risk of two layers peeling off due to the formation of a gap between both members and the penetration of water. There is no denying that it will remain.

In order to solve the above problems, the present invention can easily cope with the final process using cut pipes in laying work on site, and can be applied even when it ends with a bent pipe. It is an object of the present invention to provide a corrosion-resistant core for a pipe joint having high versatility and excellent workability, which can be easily applied to so-called knotted pipes by simultaneously laying and joining both ends in the middle.

[0014]

The anticorrosion core of a pipe joint according to the present invention is inserted across both ends of two cast iron pipes to be connected, and is provided with a plurality of flexible projections projecting on the outer peripheral surface. A fin is pressed against the inner surface of the cast iron pipe to prevent corrosion and water pollution at the end of the pipe, and has a cylindrical body 3 having an outer diameter D smaller than the inner diameter d of the cast iron pipe 1 and a center of the cylindrical body 3. A central ridge 4 projecting from the outer peripheral surface, and two or more flexible annular members each having a tip projecting higher than the inner diameter d of the cast iron pipe at regular intervals symmetrically on both sides on the outer peripheral surface of the central ridge 4 becomes more and fin 5, the annular
The tip where the fin 5 has both the bending crimping property at the tip and the strength of the root
With a narrow trapezoidal or acute triangular cross-section
All parts of the cylindrical body 3, the central ridge 4, and the annular fin 5
Is formed in an integral structure by injection molding of a flexible plastic material.

[0015] With this configuration, the cylindrical body 3 and the central ridge 4 inserted into the inner diameter side of the cast iron pipe have appropriate flexibility and strength, and the dimensional variation based on the tolerance of the inner diameter of the cast iron pipe is referred to. In addition, even when the pipe is bent, the pipe follows the pipe inner peripheral surface and is bent and absorbed. On the other hand, the plurality of flexible annular fins 5 protruding from the cylindrical body 3 are elastically deformed flexibly and elastically in response to an error or bending of the inner diameter of the pipe, and are compacted on the inner peripheral surface of the pipe. Therefore, the anticorrosion function for the cast iron pipe is maintained. Since the cylindrical body, the central ridge, and the flexible annular fin are all integrally formed of the same plastic material, there is no seam or bonding, and the elastic deformation and material strength are always integrated. The problem is solved by exchanging with each other.

In the case of an ordinary cut pipe joint, there is no problem particularly with the above-described configuration, but in the case of the so-called knotted pipe, the pipes laid from both sides are finally joined by joining along the way. There are special conditions to do so. Therefore, once the whole of the anticorrosion core is inserted into one of the cast iron pipes and kept in a standby state, the cast iron pipe to be spliced is suspended, the pipe axes are aligned, and then the anticorrosion core is pulled out. A procedure of nearly half insertion into the tube is required. This claim specifies the requirements for application to the knotted pipe, and the condition that the central ridge can be inserted into the cast iron pipe is a condition that the central ridge 4A has an outer end protruding from the outer peripheral surface. The limitation is that the diameter RA is lower than the inner diameter d of the cast iron pipe.

[0017] Proceeding to more specific requirements from the basic configuration described above, as in claim 3, the height H that protrudes from the outer peripheral surface of the circular cylinder 3, the outer diameter D of the cylindrical body, a flexible Thickness t of the root of the annular fin protrusion, minimum inner diameter d within the tolerance of cast iron pipe
When min and the maximum inner diameter are dmax, it is a desirable embodiment that D + 2t ≦ dmin and D + 2H ≧ dmax.

All of the current cast iron tubes are mass-produced by the centrifugal casting method. However, as long as the product is a cast product, it is unavoidable that the outer diameter and the thickness vary, so that an acceptable tolerance is recognized. . Depending on the combination of tolerances, a certain range of variation occurs in the inner diameter of the tube. For example, when the maximum outside diameter and the minimum thickness within the tolerance are combined, the inside diameter is theoretically maximum, and conversely, when the minimum outside diameter and the maximum thickness are combined, the inside diameter is minimum. Calculating from the tolerance of the outer diameter and the wall thickness specified by the Japan Water Works Association, the maximum inner diameter of a cast iron pipe with a bore of 250 mm or less is 11 mm (± 5.5 mm).
mm). Since the anticorrosion core is inserted into the inner surface of the pipe, it can be inserted into the cast iron pipe with the smallest inner diameter, and even when inserted into the cast iron pipe with the largest inner diameter, the flexible annular fins are sufficiently bent and crimped to the inner peripheral surface. To prevent the ingress of running water. In order to satisfy these two conditions, the outer diameter D of the cylindrical body and the protruding height H of the flexible annular fin are limited as in the above formula.

The cross-sectional shape of the flexible annular fin 5 is also an important factor. FIG. 3 is a partial longitudinal front view showing the basic concept of the cross section of the flexible annular fin according to the present invention. When the inner diameter of the cast iron pipe is small, it is necessary to reduce the force required to insert the anticorrosion core. It is necessary to choose either to increase the height of the flexible annular fins or to reduce the thickness of the flexible annular fins. Since the inside diameter is small, the flow rate in the pipe is adversely affected. When the thickness of the flexible annular fin is reduced, if it is applied to a cast iron pipe having a large actual inner diameter, the function of preventing water exchange in the pipe joint portion is adversely affected. After all, the cross-section of the flexible annular fin is trapezoidal or further advanced as an acute triangle to keep the height of the flexible annular fin as low as possible and to have a certain thickness. It is desirable to balance the flexibility and strength by making it thinner as it extends. As described later, it is necessary to appropriately set the rigidity and flexibility of the applied plastic material in consideration of the combination.

The anticorrosion core of the present invention not only has a working advantage and efficiency at the time of joining, but also has a joint function that does not always allow the cast iron pipes to be detached from each other even when laid underground and in use. The distance S between the central ridge 4 and the first adjacent fin 5 as specified in claim 4 is a condition for preventing the fin 4 from withstanding easily vibrations from the ground, uneven loads, and vibrations from underground. It is required to be larger than the maximum allowable escape amount set for the cast iron tube.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1A and 1B show a front view (A) of a partial cross section of an anticorrosion core showing an embodiment of the present invention and the inside of a receiving port 11 of a normal type cast iron pipe 1A. The longitudinal section front view (B) of the joint part which inserted and joined the incision 12 which is the front-end | tip of the incision tube 1B in the same mode as a normal insertion hole is shown. As shown in the figure, the anticorrosion core 2 comprises a cylindrical body 3, a central ridge 4, and a flexible annular fin 5 made of an integrally injection-molded plastic material having no seams or bonding. The requirements for the material of the anticorrosion core are bending pipes (± 5
°), and if the anticorrosion core is too rigid, it may come into contact with the inner surface of the cast iron pipe and damage it, or the inner lining layer may be damaged and peeled off. Becomes larger. Further, if the bend pipe is a mating partner, the pipe itself is bent, so that the determination that the pipe is more inappropriate than the bent pipe is decisive.

Considering the characteristics of the material as the anticorrosion core in consideration of these factors, it is necessary that the material has appropriate flexibility, appropriate rigidity, good resilience, and excellent corrosion resistance. To emerge as. Where to find the balance of each element requires long-term data based on experience and achievements. Table 1 summarizes the results of the suitability inspection of each material including the plastic material which is the object of the present invention. It was done.

[0023]

[Table 1]

The specific values of flexibility and rigidity are represented by the longitudinal elastic modulus. A clear classification of the longitudinal elastic modulus as a suitable material for the anticorrosion core has not yet been established at this stage. However, in order to give flexibility to a cylindrical body having a thickness of at least about 2 to 3 mm, 500 kgf / It is estimated that mm ² or less is appropriate, and we are currently in the process of confirming it. In any case, the appropriate anti-corrosion core according to the present invention, which is formed by integrally molding a plastic material having a suitable balance of flexibility and rigidity and restoring force, such as polyethylene,
It can be fully suggested from the numerical values in Table 1 that the material has much better function retention ability than other materials including the listed prior art.

As described above, the shape of the flexible annular fin increases the thickness of the protruding root of the flexible annular fin,
When the anticorrosion core is inserted into the cast iron tube, the vicinity of the tip is appropriately bent and crimped to the inner peripheral surface of the cast iron tube while the anticorrosion core is inserted into the cast iron tube, while the vicinity of the base of the flexible annular fin is rigid. The flexible annular fins maintain the subjectivity of the flexible annular fins and maintain the water seal function of the joint portion of the cast iron pipe without causing abundant and completely bent deformation. Although additional tests are required for specific dimensions and shapes, at this stage, the dimensions shown in Table 2 below were evaluated as having both a good water sealing effect and a good anticorrosion effect. are doing.

[0026]

[Table 2]

If the dimensional relationship in this range is maintained, the joining can be completed easily without requiring an excessive external force for inserting the anticorrosion core into the cast iron pipe, and the flexible annular fin is provided on the inner peripheral surface of the cast iron pipe. It was confirmed that a stable water-sealed state could be maintained without excessively bending the vicinity of the tip of the. That is, in order to perform the evaluation when selecting the appropriate material shown in Table 1 and performing the test in the form shown in Table 2, a corrosion-resistant core made of soft polyethylene was inserted into a ductile cast iron pipe joint having a nominal diameter of 75 mm, and a 3 mm
After conducting a water flow test for one month, the joint was disassembled to evaluate the water sealing effect and the anticorrosion effect. Regarding any point, a satisfactory result was left, and some rusting was observed in the inner peripheral surface of the joint portion, which is a phenomenon called so-called black rust.
This indicates that the dissolved oxygen in the water is deficient, and even if there is a slight inundation in the joint, there is no replacement of water and the water sealing effect is sufficiently maintained to prevent the progress of metal corrosion. It proved that you were doing.

The distance S from the central ridge 4 to the first adjacent and adjacent flexible annular fin is required to be longer than the maximum allowable withdrawal amount as described above. Therefore, specifically, for example, in a small diameter pipe having a nominal diameter of 250 mm or less, 2
Since it is 0 mm, at least the distance from the central ridge to the flexible annular fin is required to be 20 mm.

FIGS. 2A and 2B show another embodiment of the present invention. While the embodiment of FIG. 1 follows the shape of a normal socket and insertion hole, this case has already been described. As a result of laying work separately from both sides of the pipeline plan and joining at the final point, both ends of the pipeline extending from both are cut off. The cut ends of the tubes are coaxially opposed to each other, and are ready for final joining. In the anticorrosion core 2A applied in this case, the outer diameter R of the central ridge 4A is set to be smaller than the inner diameter of the cast iron pipe.
In this state, another cut tube 1B is suspended from above, the axes of both tubes are adjusted and aligned, and the cut tube 1A is fed to the inner diameter side of the cut tube 1B supplied later. The anticorrosion core 2A is joined by a procedure of pulling out and pushing in almost half. Since both ends of the knotting pipe face each other with cut pipes, they are joined in a water-tight manner by the connecting ring 6 and the pressing ring 7 that straddle both outer peripheral surfaces.

[0030]

As described above, the present invention has an effect of extremely efficiently and reliably assuring the protection of the cut end of a cut pipe, which is mainly generated in the final step of laying a pipeline, as a result, such as red water. Significantly reduce concerns about distributing poor quality drinking water to homes, offices and other end-use destinations. Since workability can be completed based on a certain standard specification without individual differences, there is no need to secure workers with particularly high skill levels, and it is highly expected that this will be an effective countermeasure for labor.

The effect according to claim 2 sets a unique requirement for application to knotted piping work which frequently occurs in actual construction, although it is not assumed in the prior art. Technology has the effect of clearly eliminating one issue that is not considered.

The effect according to claim 3 is a dimensional limitation that has been reached as a result of a detailed analysis of conditions specifically required for an anticorrosion core. It presents the properties of the optimal flexible annular fins conceived based on valuable data backed by experiments, and in the sense of providing the most valuable information as a realistic condition setting when moving to implementation, The effect should be maximized.

The fourth aspect of the present invention is that the most basic requirement imposed on the joint portion, that is, the prevention of falling off, is weighted to the requirement of the present invention, and means that a dimensional limitation most suited to the needs at the time of construction is presented. Large secondary effects overlap.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional front view showing an embodiment of the present invention (A) and a vertical cross-sectional front view of a joint portion after a cast iron pipe is attached (B).

FIG. 2 is a partial cross-sectional front view (A) showing another embodiment of the present invention and a vertical front view (B) of a joint portion after a cast iron pipe is attached.

FIG. 3 is a longitudinal sectional front view showing a basic form of a flexible annular fin of the present invention.

FIG. 4 is a partial vertical sectional front view of the prior art.

FIG. 5 is a vertical sectional front view of another prior art.

FIG. 6 is a longitudinal sectional front view (A) of still another prior art and a longitudinal sectional front view (B) of a joint portion after a cast iron pipe is attached.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cast iron pipe 2 Corrosion prevention core 3 Cylindrical body 4 Central ridge 5 Flexible annular fin 6 Connecting ring 7 Pressing ring 11 Receptacle 12 Cut end d Inner diameter of cast iron pipe D Outer diameter of cylindrical body R Outer diameter of central ridge S Maximum allowable Amount of escape dmax Maximum inner diameter of cast iron pipe dmin Minimum inner diameter of cast iron pipe H Height of flexible annular fin

Continuation of the front page (72) Inventor Ichiro Shiomi 1-12-19 Kitahorie, Nishi-ku, Osaka-shi, Osaka Inside Kurimoto Ironworks Co., Ltd. (56) References JP-A-61-215881 (JP, A) −36196 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16L 58/00-58/18

Claims (4)

(57) [Claims] 1. A plurality of flexible fins inserted across both ends of two cast iron pipes to be connected and projecting from an outer peripheral surface thereof are pressed against an inner surface of the cast iron pipe to prevent corrosion of the pipe end. In the anticorrosion core 2 of the pipe joint for preventing water pollution, a cylindrical body 3 having an outer diameter D smaller than the inner diameter d of the cast iron pipe 1, a central ridge 4 projecting from a central outer peripheral surface of the cylindrical body 3, Two or more flexible annular fins 5 each having a tip projecting higher than the inner diameter d of the cast iron pipe at regular intervals symmetrically to both sides on the outer peripheral surface of the central ridge 4.
And the annular fin 5 has a bending crimping property at the tip and a root.
Of a tapered trapezoid or sharp triangle that balance the strength of
Surface, and the cylindrical body 3, the central ridge 4, the annular
A corrosion-resistant core for a pipe joint , wherein all parts of the joint 5 are formed as an integral structure by injection molding of a flexible plastic material. 2. The anticorrosion core of a pipe joint according to claim 1, wherein the outer diameter RA of the tip of the central ridge 4A protruding from the outer peripheral surface is smaller than the inner diameter d of the cast iron pipe. Te 3. A process according to claim 1 or 2 smell, the height H that protrudes from the outer peripheral surface of the circular cylinder 3, the outer diameter D of the cylindrical body, the flexible annular fin projecting portion of the base of the wall thickness t, cast iron pipes Wherein D + 2t ≦ dmin and D + 2H ≧ dmax, wherein the minimum inner diameter dmin and the maximum inner diameter dmax are within the allowable tolerances. 4. The distance S between a central ridge 4 and an adjacent first flexible annular fin 5 according to claim 1.
Is larger than the maximum allowable escape amount defined for the cast iron pipe.