JPS631113B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pipeline cleaning plug (hereinafter simply referred to as a plug), and more particularly to an improvement in a pipeline cleaning plug made of foamed polyurethane resin that is propelled through a pipe by fluid pressure.

Conventionally, the pipeline cleaning plug used is first molded using foamed polyurethane resin to form a foam body (hereinafter simply referred to as the base body).
The inner wall of the pipeline is molded into the shape of a cannonball, for example, and then manually coated with polyurethane elastomer to a certain thickness, and the plug surface is reinforced with an abrasion-resistant coating (hereinafter simply referred to as the skin). Most of them increased the effectiveness of cutting and cleaning deposits. However, in such conventional products, the skin is created by applying polyurethane elastomer to the surface of the base after the base is molded, and the tensile strength of the skin is insufficient and the elongation rate of the skin is lower than that of the base, making it difficult to create pipelines. When used for cleaning, the skin often peels off from the adhesive interface with the substrate, deep cracks from the skin to the substrate occur, and even breakage occurs, reducing the pipeline cleaning effect.

Furthermore, in order to improve the cleaning effect of conventional plugs,
When applying polyurethane elastomer onto a substrate, an abrasive was sprinkled on the surface before the polyurethane elastomer dried, but according to this method, the abrasive adhered continuously and densely to the surface, causing pipe damage. The grinding effect on the inner wall of the line was small, and the abrasive material easily peeled off when the plug was used.

Furthermore, since conventional products use the manufacturing method described above, they require two or more steps, and in particular, manual application of polyurethane elastomer takes a long time, resulting in extremely poor workability and productivity. This was also a major obstacle in mass production.

Therefore, the main object of the present invention is to provide a plug which improves the drawbacks of these conventional plugs, and which is particularly durable and highly effective in cleaning.

A further object of the present invention is to provide a plug in which the skin does not peel off or come off together with the base, neither cracks nor breakage occurs, and the abrasive material does not come off.

Furthermore, it is an object of the present invention to provide a plug that is easy to manufacture and inexpensive.

The plug of the present invention improves the above-mentioned drawbacks of conventional products, and can simultaneously create a base made of a flexible internal foam and a high-strength, highly flexible skin in just one molding process. This is a new plug that is continuously molded into one piece and has dramatically improved adhesion and cleaning effectiveness.

A conventional plug typically has a structure as shown in FIG. 1, in which a skin 1 is coated on a base 2. The skin 1 is made of polyurethane elastomer, and the base body 2 is made of foamed polyurethane resin. The shape of the plug is generally a simple bullet shape, with one short cylindrical front end 3 having a hemispherical shape and one rear end 4 having a flat shape. The surface skin 1 is also coated on the planar rear end 4. The epidermis may have an abrasive material (not shown) attached to its surface. In addition to the plug shown in FIG. 1, there are also conventional plugs in which, for example, a skin is coated on the surface of a substrate in a spiral or criss-cross pattern.

The plug of the present invention has a substantially cylindrical shape consisting of a base and a skin that are continuously integrally molded of polyurethane resin, and the base has a density of 0.12 to 0.35 g/cm ³
It is a foamed elastic body, and the skin has a thickness of 2 to 3 m/
The plug is an elastic body having a density of 0.80 to 1.40 g/cm ³ and having greater strength and abrasion resistance than the base body, and has an apex at one end of the plug approximately on the central axis of the plug. It has a substantially conical recess with an apex angle θ of 40°≦θ≦90°, and the bottom of the recess opens toward the peripheral surface of the plug or leaves a thickness at most equivalent to the outer skin at the peripheral portion. It is characterized by the fact that

The plug of the present invention will be described in detail with reference to the drawings. For example, it has a structure as shown in FIG. ing. The appearance of the plug shown in Figure 2 is the front end 3 of the plug.
is hemispherical, and has a bullet shape with a substantially conical concave portion having an apex angle θ of 40°≦θ≦90° at one rear end 4. The top of this conical recess is located approximately on the central axis of the plug. Furthermore, although the bottom of the recess is open leaving at most a thickness corresponding to the skin around the periphery, it may be open toward the circumferential surface of the plug. The front end 3 of the plug can also be conical. The skin 1 and the base 2 are made of the same material, for example a polyurethane resin that produces a dense surface layer when foamed, but the skin 1 is made of an elastomer-like elastic body, and the base 2 is made of the same material.
is formed continuously and integrally to form a foamed elastic body. Skin 1 is significantly superior to substrate 2 in terms of strength and abrasion resistance, but in terms of elongation they are equal. As described above, the skin 1 and the base 2 are continuous integrally molded products, and are not laminated together using an adhesive or the like.

The plug of the present invention has a base density of 0.12 to 0.35.
g/cm ³ , the density of the epidermis is 0.80 to 1.40 g/cm ³ , and the thickness of the epidermis is 2 to 3 m/m. However, its tensile strength is 4 to 6 kg/cm ² for the base and 35 to 50 for the epidermis.
Kg/cm ² , the tensile strength ratio is 1 for the base and 7 or more for the skin, and the elongation rate of the skin is 500 to 600, the same as the base.
%, and the skin is superior to conventional products in both tensile strength and elongation. Incidentally, the tensile strength of the base of the conventional product is 7.
The tensile strength of the skin was 30-32 Kg/ ^{cm 2 and} the elongation rate was 240-270%.

The skin of the plug described above has sufficient abrasion resistance by itself and satisfies the function of cleaning the inner wall of the pipeline, but if necessary, the abrasion resistance and abrasiveness of the plug can be further improved. An abrasive material can also be blended into the epidermis to improve this effect. As the abrasive, pulverized diamond sand of 0.074 to 0.174 mm is used, and an abrasive with a particularly rich ridge angle has a great effect on grinding deposits on the inner wall of the pipeline. Further, the same effect can be obtained by using silica sand powder instead of diamond sand.
The amount of the abrasive to be added is preferably 1 to 6 parts by weight, particularly preferably 2 to 4 parts by weight, per 100 parts by weight of the raw material for the plug (polyurethane resin). If the amount of abrasive added is less than 1 part by weight, the effect will be small, and if it is more than 6 parts by weight, the tensile strength and elongation of the skin will decrease.
This is because it becomes easily damaged.

The abrasive material is dispersedly embedded in the epidermis and is integrated with the epidermis. Therefore, even when the plug is actually used, the abrasive material does not come off, and the effect of grinding on the deposits on the inner wall of the pipeline is great.

As an example of the shape of the plug of the present invention, FIG. 2 shows a bullet shape having a substantially conical recess with an apex angle of θ at the rear end 4, but the shape is not limited to this. , various shapes can be selected depending on the application and usage conditions. for example,
In FIG. 2, the front end 3 of the plug may be planar, and the rear end 4 may be cylindrical with a conical recess as described above. In the case of a simple pipeline that does not include a T-shaped pipe, an elbow pipe, a step, a valve, etc., a plug having such a shape can be suitably used, and the length of the plug may also be relatively short. In addition, in the case of an elastic plug in which the front end 3 of the plug is formed in a hemispherical or conical shape and the rear end 4 has a conical recess, obstacles such as a T-shaped pipe, an elbow pipe, a step, a valve, etc. are included. Even when used in complex pipelines, it is suitable because it can easily adapt to changes in the shape of the pipe.
As mentioned above, the shape of the plug is not particularly limited as long as it is cylindrical or has a shape changed from a cylindrical shape.

A preferred method for manufacturing the plug of the present invention will be explained.
As a raw material for the plug of the present invention, a polyurethane resin stock solution is used which forms a surface layer with a high density and a base layer with a low density upon foaming. This polyurethane resin stock solution is a two-component system consisting of P solution consisting of polyisocyanate and C solution prepared by heating and melting a mixture of polyol, catalyst and diol crosslinking agent, cooling it to 20℃, adding a blowing agent and stirring. be.
Diphenylmethane diisocyanate (MDI) type and tolylene diisocyanate (TDI) type are preferably used as the polyisocyanate of P liquid.
Particularly preferred is clade MDI (trade name PAPI,
(manufactured by Kasei Upjiyon Co., Ltd.).

Furthermore, as the polyol for liquid C, polyether polyols, such as poly(oxypropylene ether) diol, are preferably used, and specific examples include Sannix PP series (trade name, manufactured by Sanyo Chemical Industries, Ltd.). . As a catalyst,
Amine-based cross-linking agents, particularly triethylene diamine, are preferred; specifically, DABCO 33LV (33% triethylene diamine and 67% dipropylene glycol) (trade name, manufactured by Toyo Soda Kogyo Co., Ltd.) is preferred; as the diol-based crosslinking agent, Particularly preferred are ethylene glycol or 1,4-butanediol. As the blowing agent, fluorine-based ones are preferable, and trichloromonofluoromethane (CCl ₃ F) is particularly preferable, and a specific example is Flon-11 (manufactured by Mitsui Fluorochemical Co., Ltd.).

Specifically speaking, the composition of liquid C is preferably 100 parts by weight of polyol, 1 to 2 parts by weight of catalyst, 5 to 10 parts by weight of diol crosslinking agent, and 10 to 20 parts by weight of blowing agent.

Therefore, keep the P solution at 30℃, and keep the C solution at 20℃~23℃.
℃, keep the mold at 45℃~40℃, and first P
The ratio of liquid and C liquid is preferably about 1:3 (for example, P
Stir the mixture (55 parts of liquid and 165 parts of liquid C) for 8 to 10 seconds with a stirrer at 2500 rpm, then immediately put it in the mold and cover it with a lid. After this
Cure at 40℃ for about 20 minutes. As a result, the central substrate becomes a foamed elastic body due to the properties of the polyurethane resin described above. The next part of the skin loses heat to the mold, which has high thermal conductivity, and generates gas. At this time, gelation is delayed compared to the substrate, so the bubbles collapse and the gas escapes. Thereafter, the internal foam fills the mold, and the effect of overpack is added to generate firing pressure. As this foaming pressure increases, the boiling point of the blowing agent rises, and foaming is suppressed and no foaming occurs, and the skin part becomes an elastomer-like elastic body that has significantly greater strength and abrasion resistance than the base material, and the base material and the skin become continuous and integral. is formed.

Further, as described above, an abrasive can be added to the polyurethane resin in advance to further improve the wear resistance and abrasiveness of the plug. In this case, depending on the foaming density distribution of the polyurethane resin, the abrasive material also accumulates on the dense skin and becomes integrated with the skin. Therefore, the wear resistance of the plug and the grinding effect on the pipeline inner wall can be improved.

The plug of the present invention, which is slightly thicker than the inner wall of the pipe, is inserted into the pipeline, and fluid pressure, such as air pressure or water pressure, is applied to the rear end of the plug to propel it forward. At this time, a force is generated in the elastic plug that tends to expand toward the inner wall of the pipeline, so that the deposits on the inner wall of the pipeline are ground away by the advancing plug.

According to the plug of the present invention, since the skin and the base are formed continuously and integrally, the skin does not peel off from the base during use, and the elongation rate of the skin and the base is equal and large, so there is no cracking. It does not occur. Further, even when an abrasive material is used, the abrasive material is embedded in the epidermis and is integrated with the epidermis, so it does not come off during use.

The present inventors mechanically studied the shape of the plug in order to further enhance the durability and cleaning effect of the inner wall of the pipe of the improved plug according to the present invention.

As shown in Figure 3, for comparison, a simple bullet-shaped elastic foam model (length 20 cm x diameter 8 cm) with a flat rear end and no conical recess was inserted into the pipeline, and the rear end of the model A uniformly distributed pressure of 3 kg/cm ² was applied to 4, and the stress distribution in the radial direction of the side surface 5a of the model in contact with the pipeline inner wall 5 of the model was calculated. This stress distribution is shown in FIG. The force acting from the side of the model toward the inner wall of the pipeline is defined as tensile stress, and the force acting from the side of the model toward the center of the model is defined as compressive stress. According to Figure 4, the tensile stress gradually increases from the front to the rear, and from the rear end to
It reaches a maximum value of 0.8 Kg/cm ² at around 23 m/m 6, then rapidly decreases, and changes from tensile stress to compressive stress at around 8 to 17 m/m from the rear end 7, and at the rear end 8, the maximum compressive stress is 0.5 It can be seen that it reaches Kg/cm ² . From this, the latter half, where the radial tensile stress is concentrated, largely contributes to grinding and cleaning the pipeline inner wall. However, it can be seen that the rear end contributes little to grinding and cleaning, and in the transition region 7 from tensile stress to compressive stress, shearing stress acts on the cross section of the model within this region. The above stress distribution was calculated by the finite element method using an electronic computer, and the Young's modulus of the model was varied between 1.5 and 90 Kg/cm ² and the Poisson's ratio was varied between 0.45 and 0.49. A similar trend was observed in this case.

The above stress distribution analysis shows that in a simple bullet-shaped plug with a flat rear end, there is a risk of cracking in the direction perpendicular to the plug axis in the vicinity of 8 to 20 m/m from the rear end, and that there is a risk of cracking in the direction perpendicular to the plug axis. It can be seen that the effect is reduced at the rear end of the plug, i.e. 6-8 in FIG.

In FIG. 5, a foamed elastic model according to the present invention having a conical concave portion with an apex angle of θ is inserted into a pipeline, and the rear end surface 4 of the model is shown as indicated by an arrow.
The case where a uniformly distributed pressure of 3 kg/cm ² is applied to is shown. As mentioned above, the apex angle θ of the conical recess was varied and the stress distribution in the radial direction of the side surface 5a of the model in contact with the pipeline inner wall 5 was analyzed by the finite element method using an electronic computer. 6,7,
As shown in Figure 8, the following was clarified from this and the results of the experiment.

(1) The maximum tensile stress of the plug is 2.5-4.5Kg/ ^cm2 ,
The frictional force between the inner wall of the tube and the plug is increased by 3 to 4 times compared to the case without a conical recess at the rear, that is, in the case of a simple bullet shape, and the cleaning effect of the plug is also increased accordingly. This maximum tensile stress increases as θ becomes smaller, but if θ is too small, the wall around the rear part becomes thin and easily damaged, so it is better not to reduce it too much. In the case of the plug of the present invention, the tensile strength of the skin is 35 kg/cm ² or more, and the skin is formed even in the recessed portions, so that θ can be made considerably small. Preferably, 40°≦θ≦90° is effective for pipeline cleaning. Particularly preferably, 55°≦θ≦65°.

(2) The distribution of tensile stress in the plug gradually increases monotonically from the front to the rear.
Unlike the case where there is no rear recess, there is no sudden change in stress, especially a change from tensile stress to compressive stress, so damage due to stress strain does not occur.

(3) In the case of a plug with a concave portion at the rear as in the present invention, even if the bend of the pipeline is close to a right angle or the pipeline is otherwise complicated, the plug may be damaged when passing through the concave portion. In addition to fully adapting to the bends of the pipeline without causing any damage, the back pressure applied to the rear end 4 when passing through the bend becomes appropriate, and the plug is temporarily removed from the inside (recess) of the balloon. It expands outward and firmly adheres to the inner wall of the pipeline bend, making it possible to clean the pipeline without causing pressure loss, and is especially effective for cleaning the bend. demonstrate.

(4) The recesses at the rear of the plug explained above are the 5th, 6th,
Although the shape is a simple cone as shown in FIGS. 7 and 8, a cone shape as shown in FIG. 9 may also be used.
That is, the bottom of the conical recess shown in FIG. 9 is composed of a skin 11b with a thick portion 11a corresponding to the skin remaining around the flat surface of the rear end of the plug.

The conical recess described above is preferable in that the tensile stress increases gradually and uniformly from the front to the rear.

However, the size of the recess must be such that the force of the fluid pressure that propels the plug and the force that presses it against the inner wall of the pipeline are maintained in an appropriate balance for the plug to function as a plug.

(5) Another advantage of the present invention is that if a polyurethane resin is used as a raw material that produces a high-density surface layer and a low-density base during foaming, the skin and base can be formed in one step by simply modifying the mold. The manufacturing cost is low because it is a finished product, and the raw material cost is low because the concave portion is provided, so less raw material is required.

In addition to cleaning pipelines, the plug of the present invention can be used to
It can also be used to separate and transport different fluids through pipelines. In the present invention, even when used for separating and transporting different types of fluids, the adhesiveness to the pipe wall is high and the sealing performance at pipeline bends is improved, so that the separation of different types of fluids can be sufficiently maintained.

Examples will be described below.

Comparative Example 1 Using a conventional simple bullet-shaped plug (8.1 cmφ x 20 cm) made of a polyurethane foam whose surface was entirely coated with polyurethane elastomer, a pipeline inner wall cleaning test was conducted according to the following test method.

Test method Figure 10 shows the test plant for this test. A pipeline 14 consisting of a gas pipe with a diameter of 75 m/m has three right-angled elbows 15 and a translucent plastic bend hose 24 interposed in the middle, and a launcher 22 and an air compressor 18 are connected to the rear end. . For the test, the rear end of the launcher 22 was opened and sand 17 was sprinkled into the pipeline 14 as test dust, and then the test plug 16 was inserted.
Tighten the rear end of the launcher until the compressed air pressure is 3.5
When Kg/cm ² (gauge) is reached, the valve 19a is opened and the plug 16 is fired from the launcher 22. The plug 16 is propelled while cleaning the inner wall of the pipeline 14 and pops out from the tip 20. As a result of the cleaning test, as shown in FIG. 11, several scratches 30 appeared on the side surface of the plug, and peeling of the skin 31 occurred at two places on the rear half. In addition, several deep cracks 32 extending from the skin to the base were formed in the circumferential direction at a location approximately 15 to 20 mm from the rear end, and were brittle.

Comparative Example 2 As shown in Fig. 12, regarding a conventional simple bullet-shaped plug (8.1 cmφ x 20 cm) in which polyurethane elastomer is applied in a criss-cross pattern, leaving a part of the diamond-shaped base portion 35 on the surface of the polyurethane foam. A cleaning test similar to Comparative Example 1 was conducted.

As shown in FIG. 12, the plug after the cleaning test has several scratches 30 on the side surface of the skin, the exposed base portion 35 is worn, and the exposed base portion 3
At the boundary between 5 and the elastomer portion 36, cracks 32 occurred almost in the base body. This is the base body exposed part 35
This is because the elastomer portion 36 has lower strength and wear resistance than the elastomer portion 36, and expands more. In addition, the crack 31 was particularly deep in a portion near the rear end of the plug, and the elastomer in that portion was peeled off.

Example 1 A polyurethane resin stock solution consisting of liquid P and liquid C having the following composition was used.

P-liquid crude MDI (trade name: PAPI, manufactured by Kasei Upjiyon Co., Ltd.) C-liquid poly(oxypropylene ether) diol: Sannix PP1000 (trade name, manufactured by Sanyo Chemical Industries, Ltd., average molecular weight: 1000) 100 parts by weight, as a catalyst: DABCO 33LV (trade name, manufactured by Toyo Soda Kogyo Co., Ltd.) 2 parts by weight 1,4-butanediol as a crosslinking agent 8 parts by weight Freon-11 (manufactured by Mitsui Fluorochemical Co., Ltd.) as a blowing agent 15 parts by weight Composition as described above 48 parts by weight of P liquid, C liquid
After putting 192 g of polyurethane resin stock solution weighed at a ratio of 144 parts by weight into a container and stirring it with a stirrer for 8 seconds,
The second mold was poured into a mold of 8.1 cmφ x 20 cm and had a conical recess of θ = 60° at the rear, kept at 40°C, and foamed (in this case, the product weight was 131g).
A plug having a concave portion of θ=60° at the rear as shown in the figure was molded, and a cleaning test similar to Comparative Example 1 was conducted. As shown in FIG. 13, the plug after the cleaning test had only a few scratches 30 on the epidermis, and no cracks or peeling of the epidermis at all. The reason why the scratches mentioned above occur relatively forward is due to casting burrs on the elbow.

In the case of Comparative Examples 1 and 2, when the plug 16 passes through the bend 15 in FIG.
On the other hand, in the case of this example, almost no dust was ejected when the plug 16 passed through the bend 15, and the dust was ejected almost at the same time as the plug 16 ejected from the pipeline tip 20. Therefore, it was confirmed that the plug 16 was in close contact with the inner wall of the pipe at the bend portion 15.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing an example of a conventional plug in which polyurethane foam is entirely coated with elastomer, Fig. 2 is a longitudinal cross-sectional view of the plug of the present invention, and Fig. 3 is a simple bullet-shaped elastic foam model inside a pipe. Fig. 4 is a stress distribution diagram in the radial direction of the model when pressure is applied to the rear end of the model in Fig. 3, and Fig. 5 shows a conical recess at the rear end. Figures 6, 7, and 8 are vertical cross-sectional views showing the foamed elastic model inserted into the pipe, and the stress in the radial direction of the model when pressure is applied from the rear of the model in Figure 5. 9 is a longitudinal sectional view showing a modification of the plug of the present invention in FIG. 2, FIG. 10 is a side view including a partial cross section of the plug testing device, and FIG. 11 is a polyurethane foam with elastomer. The 10th plug of the conventional plug which is fully covered with
Side view showing test results using the test equipment shown in Figure 1.
Figure 2 is a side view showing the test results of a conventional plug in which a polyurethane foam is coated with an elastomer in a criss-cross pattern, using the testing apparatus shown in Figure 10;
The figure is a side view showing the test results of the simple bullet-shaped plug of the present invention using the test apparatus of FIG. 10. Explanation of symbols of main parts, skin...1, base...
2, Front end...3, Back end...4, Pipe inner wall...5, Model side...5a, Maximum tensile stress point...6, Stress transition area...7, Maximum compressive stress point...8, Pipeline ...14, Right angle elbow...15, Plug...
16, Sand...17, Air compressor...18, Pressure gauge...19, Pipeline tip...20, Launcher...22, Plastic hose...24.

Claims (1)

[Scope of Claims] 1. A substantially cylindrical plug for pipeline cleaning consisting of a base and a skin that are continuously integrally molded of polyurethane resin, the base having a density of 0.12 to
It is a foamed elastic body of 0.35 g/cm ³ , and the skin is an elastic body with a thickness of 2 to 3 m/m and a density of 0.80 to 1.40 g/cm ³ that has greater strength and abrasion resistance than the base. , one end of the plug has a substantially conical recess with an apex angle θ of 40°≦θ≦90°, the apex of which is approximately on the central axis of the plug, and the bottom of the recess is located on the peripheral surface of the plug. A pipeline cleaning plug characterized in that it has an opening toward the periphery, or leaves a thickness equivalent to at most the skin around the periphery. 2. The pipeline cleaning plug according to claim 1, wherein the other end of the cylindrical shape is semispherical or conical. 3. The pipeline cleaning plug according to claim 1, wherein the tensile strength of the skin is 7 times or more the tensile strength of the base. 4. The pipeline cleaning plug according to claim 1, wherein the skin contains an abrasive. 5. The pipeline cleaning plug according to claim 4, wherein the abrasive is diamond sand or silica sand. 6. The pipeline cleaning plug according to claim 4, wherein the amount of the abrasive is 2 to 4 parts by weight based on 100 parts by weight of the polyurethane resin.