JPH04102788A - Rubber hose having large displacement and low stress and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a long size rubber hose having small deformation reaction (stress) and a little of pressurized deformation at a low cost by shrinking a heat shrinkable fiber layer in the direction for reducing the inner diameter of the rubber hose with residual heat shrinkage at the time of initial heating and vulcanization of the heat shrinkable fiber layer, and forming the rubber hose into a cylindrical hose, of which inner surface is formed into a bellows. CONSTITUTION:The inner surface rubber 2, a reinforced fiber layer 3 and reinforcing wires 4 are laminated on a cylindrical flat core 1, and furthermore, a heat shrinkable fiber layer 5 is laminated between the reinforcing wires 4 with the same pitch, and a reinforced fiber layer 6 is arranged outside of them, and the periphery is covered with the outer surface rubber 7, and heating and vulcanization is performed to form a rubber hose 8 having the smooth inner surface. Next, this rubber hose 8 having the smooth inner surface is exposed in the hot air or the pressurized steam under the condition that the core 1 is removed, and is heated till the shrinkable fiber shows a predermined shrinkage to form a cylindrical bellows hose 9. Shrinkage is generated at a part, where the influence of the reinforcing wires is not given because of the residual heat shrinkage of the heat shrinkable fiber layer 5 at the time of initial heating and vulcanization, in the direction for reducing the inner diameter. Bending reaction is thereby reduced extremely to prevent pressurizing deformation.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is used as an elastic piping joint in various parts of piping when transferring fluid, and can take a large displacement with a shorter length and at the same time This invention relates to a large displacement, low stress rubber hose with small force and a method for manufacturing the same.

[Prior art] There are three types of hose elastic pipe joints: metal, resin, and rubber.
Two materials are known.

If it is made of a rigid body such as metal, the part that comes into contact with the fluid, that is, the inner surface, is made uneven (bellows, corrugated) to reduce the deformation reaction force and take a large displacement. On the other hand, in the case of a resin hose made of flexible material, the inner surface is smooth and the large allowable deformation of the resin itself is used when deforming, and the inner surface is also uneven, just like with metal hoses. There are cases where it is done. When rubber is the main material, like resin, there are two types: one with a smooth inner surface and one with a bellows-like inner surface.

By the way, the following method has been proposed as a method for manufacturing this type of bellows-shaped hose using rubber as the main material.

■ The inner mold is bellows-shaped and the inner rubber is placed on top of the mold.
Reinforcement wire, reinforcing fibers, and outer rubber are laminated, and then a tightening cloth is wrapped around the outer layer and steam vulcanization is performed directly, or an outer mold is incorporated and vulcanized. How to remove it and use it as a product.

■ Laminate inner rubber, reinforcing wire, fibers, and outer rubber onto a smooth cylindrical core metal, vulcanize it, and pull out the cylindrical core metal to obtain a cylindrical (smooth inner surface) vulcanized hose. Next, insert a core metal slightly smaller than the inside diameter of the hose into the hose, tighten it firmly with a rope so that it is inserted between the reinforcing wires wound spirally from the outside of the hose, and forcefully press it to create a bellows. A method of heating and vulcanizing again while the inner and outer parts are still formed.

[Problems to be Solved by the Invention] However, in the case of (2), the mold is bellows-shaped, so there is a drawback that the mold is expensive. Also, in terms of manufacturing, long products cannot be produced.
In particular, it is difficult to remove the inner bellows-shaped portion from the inner mold. Furthermore, hoses with metal fittings on their end surfaces cannot be manufactured due to the structure of the mold.

Furthermore, it is difficult to form rubber on the inner groove.

On the other hand, in the case of (2), it is difficult to manufacture long products due to the process of inserting a small-diameter core metal into a material that has been vulcanized. Further, the rope winding work requires a large amount of labor and man-hours, which is not desirable in terms of cost.

In other words, all of the conventional methods mentioned above are expensive, difficult to manufacture long products, and products are subject to large deformation due to pressure, especially in areas that are concave on the inner surface. On the contrary, there was a problem in that it became convex and the effect of forming an inner bellows was reduced.

The purpose of the present invention is to compensate for these shortcomings in the prior art, and to provide a rubber hose that is long, inexpensive, has stable characteristics with little deformation under pressure, and has low deformation reaction force (stress) without requiring particularly large capital investment. This is what we provide.

[Means for Solving the Problems] The present invention laminates an inner rubber, a reinforcing fiber layer, and a reinforcing wire on a smooth core bar, and further laminates a heat-shrinkable fiber layer at approximately the same pitch between the reinforcing wires. After forming a smooth inner rubber hose by covering the outer periphery with outer rubber and vulcanizing it, the smooth inner rubber hose is then heated with the core metal removed to form a heat-shrinkable fiber layer. A large displacement hose characterized by shrinking the heat-shrinkable fiber layer in the direction where the inner diameter becomes smaller in the part not affected by the reinforcing wire due to residual heat shrinkage during the initial heating and vulcanization, creating a cylindrical hose with an inner bellows shape. This is a method for manufacturing a low stress hose. In addition, heat-shrinkable fibers are embedded in the gaps between reinforcing wires arranged spirally within the rubber layer at almost the same pitch, and the reinforcing fibers are placed on the inner surface of the heat-shrinkable fibers. This is a large displacement, low stress rubber hose constructed as a bellows-shaped cylindrical structure.

By the way, it is also possible to manufacture a hose in the same way without using heat-shrinkable fibers by filling the heat-shrinkable fiber layer with rubber and using shrinkable fibers in the reinforcing fiber layer, but the reinforcing fiber layer does not maintain its pressure-resistant strength. Therefore, it is preferable to arrange the reinforcing fibers at an angle of 45° to 70° with respect to the axial direction of the hose. The force and amount of contraction that squeezes out does not occur. Therefore, it is preferable to embed shrinkable fibers having a larger shrinkage force and amount than the reinforcing fibers between the reinforcing wires. In other words, the reinforcing wire is generally 80~
Although the fibers are arranged in a spiral at an angle of 88 degrees, the shrinkable fibers are also arranged at an angle of 80 to 88 degrees at the same pitch, so there is little loss in the direction of shrinkage. In addition, since the amount of reinforcing wire can be buried to a thickness greater than or equal to the diameter of the reinforcing wire, a large amount of shrinkage can be expected as a whole.

The difference in level between the small diameter part and the large diameter part of a bellows-shaped cylindrical hose is determined by the thermal properties of the heat-shrinkable fibers.

Therefore, the shrinkable fiber is selected appropriately depending on the required bellows level difference, but generally the vulcanization temperature of the rubber hose is 13
Nylon with sufficient heat shrinkage at 0' to 170℃,
Polyester is preferred, but is not particularly limited.

When vulcanization is performed using a core bar with a flat inner surface, the absorbent fibers are in contact with the core bar through the inner rubber, so sufficient shrinkage stress remains, but reinforcement is applied to the inside of the shrink fibers. It is necessary to take measures to prevent shrinkage fibers from getting caught in the inner rubber when the rubber is in a fluid state during heating and has some rigidity, such as fibers.

In this way, the initial vulcanization is completed in a state where the shrink fibers have a sufficient residual heat shrinkage rate, and a hose with a smooth inner surface is produced.

By heating this hose again to a state close to the initial vulcanization temperature (130 to 170°C) with the core metal removed, only the shrinkable fibers between the reinforcing wires will contract freely, and the inner surface will become This produces a bellows-shaped hose. Note that the strength of the reinforcing wire does not need to be particularly higher than that of normally used materials, but it is necessary to make the winding pitch somewhat accurate.

Also, when revulcanizing (reheating) the hose, it is easier to cause shrinkage on average if the entire length is not restrained, but if you want a larger bellows step, one method is to compress the hose between the shafts during heating. It is.

[Operation] Since this invention utilizes the thermal contraction of fibers, it does not easily return to its original flat shape even when fluid pressure is applied, so there is little risk of deformation due to pressurization. Therefore, unlike conventional rubber hoses of this kind, the concave portion on the inner surface does not become convex due to pressure, thereby reducing the effect of forming an inner bellows. In addition, it does not require any special large-scale equipment, nor does it require the man-hours required for forced deformation as in the prior art, making it possible to provide inexpensive products.

[Example] In Fig. 1, first, an inner rubber 2, a reinforcing fiber layer 3, and a reinforcing wire 4 are laminated on a cylindrical smooth core metal 1, and then heat-shrinkable material is placed in the gaps between the reinforcing wires 4 at almost the same pitch. The fiber layers 5 are laminated, a reinforcing fiber layer 6 is further arranged on the outside of the heat-shrinkable fiber layer 5, the outer periphery is covered with an outer rubber 7, and the hose is heated and vulcanized to form a smooth inner rubber hose 8. In this rubber hose 8 with a smooth inner surface, the heat-shrinkable fiber layer 5 has been completely vulcanized without being obstructed by the core metal 1 and shrinking, and has smoothness and retains a sufficient amount of residual heat shrinkage.

Next, as shown in FIG. 2, this rubber hose 8 with a smooth inner surface is exposed to hot air or pressurized steam with the core bar 1 removed, heated until the shrinkable fibers show a predetermined contraction, and then shaped into a bellows shape. cylindrical hose 9.

The shrinkage is due to residual heat shrinkage of the heat-shrinkable fiber layer 5 during initial heating and vulcanization, and the shrinkage occurs in a direction in which the inner diameter becomes smaller in a portion not affected by the reinforcing wire.

However, the present invention is not limited to the above embodiments. For example, as shown in FIG.
A rubber hose 10 with a smooth inner surface is vulcanized and molded on the outside of the rubber hose 10, and this smooth rubber hose 10 is formed as shown in FIG.
It is also possible to adopt a method of reheating the core bar 1 with it removed.

Next, the embodiment shown in FIGS. 1 and 2 was tested.

The inner smooth rubber hose 8 has a total length of 1000 mm and an inner diameter of D =
φ100mm+, outer diameter D2=φ118■, pitch P of reinforcing wire 4=20mm, inner rubber 2 is natural rubber 60°,
It is 3.0 mm. Reinforcing fibers 3.6 are all polyester 840d, 20 pieces/1nch as sudare fibers,
The thickness is 1.0 mm. Although the angle was 54° in both cases, the reinforcing fibers 3 and 6 were attached in opposite directions. The reinforcing wire 4 was a hard steel wire with a diameter of φ3 and a pitch of 20 mm. The outer rubber 7 is natural rubber 60° 1.0 mm, and the heat-shrinkable fibers are nylon 1260d, and 50 fibers are embedded in each pitch of the reinforcing wire 4.

The core metal used during initial vulcanization had a diameter of 100 mm, and vulcanization was carried out at a temperature of 150° C. for 50 minutes. As a result of heating and shrinking this without the core metal, the innermost diameter was obtained. = φ95mm, inner diameter D'1 = φ100nua, outermost diameter D'2 = φ1181TIIIi Tonatsuta.

As a result of measuring the 90° bending reaction force of this hose, at a total length of 1000 mm, it was 12 hgf in the state of a smooth inner rubber hose before contraction, and 7 hgf' after contraction. Further, when the total length was 300 mm, the compression reaction force of 10 mm was 70 hgf before contraction and 15 hgf' after contraction.

The test conditions for the 90° bending reaction force were to fix one end of the hose, pull the other end in its centripetal direction, and measure the force F at which a hose with a total length of 1000 mm would bend at a 90° angle. In the compression reaction force test, one end of the hose was fixed, a load was gradually applied from one end, and the load F when the hose was compressed by 10 mm without buckling was measured.

[Effects of the Invention] As described above, this invention is a low-stress rubber hose that undergoes displacement due to thermal contraction of fibers, so the bending reaction force is extremely small.
In addition, the compression reaction force for short products is also reduced, so it is highly effective for installing and removing products, expanding and contracting piping, and absorbing vibrations. In addition, as mentioned above, when a fluid pressure is applied to the inside of a hose, the conventional hose with an uneven core undergoes large pressure deformation, but the hose according to the present invention utilizes the thermal contraction of fibers. Therefore, even if fluid pressure is applied, it does not easily return to its original flat shape, so deformation due to pressurization is prevented. Moreover, it does not require any special large-scale equipment, nor does it require the man-hours required for forcible deformation as in the prior art, making it possible to provide inexpensive products.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of the essential parts of a rubber hose with a smooth inner surface for manufacturing rubber hoses, which is an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the essential parts of a rubber hose, which is an embodiment of the invention, and FIG.
The figure is an enlarged sectional view of a main part of a rubber hose with a smooth inner surface for manufacturing a rubber hose, which is a spaced-apart embodiment, and FIG. 4 is an enlarged sectional view of a main part of a rubber hose, which is a spaced-apart embodiment. 1... Core metal 2... Inner rubber 3.6.
...Reinforcement fiber layer 4...Reinforcement wire 5...Heat-shrinkable fiber layer 8.10...Smooth inner surface rubber hose

Claims (2)

[Claims] (1) Laminate inner rubber, reinforcing fiber layer, and reinforcing wire on a smooth core metal, then layer heat-shrinkable fiber layers at almost the same pitch between the reinforcing wires, and cover the outer periphery with outer rubber. After molding a smooth inner rubber hose by vulcanization, this smooth inner rubber hose is heated with the core bar removed, and due to residual heat shrinkage of the heat-shrinkable fiber layer during initial heating and vulcanization. A method for manufacturing a large-displacement, low-stress rubber hose, characterized by shrinking a heat-shrinkable fiber layer in a direction in which the inner diameter decreases in a portion not affected by a reinforcing wire, thereby forming a cylindrical hose with an inner bellows shape. (2) Heat-shrinkable fibers are embedded in the gaps between reinforcing wires arranged spirally in the rubber layer at almost the same pitch, reinforcing fibers are arranged on the inner surface of the heat-shrinkable fibers, and the heat-shrinkable fibers are A large-displacement, low-stress rubber hose that is held in a cylindrical structure with a bellows-like inner surface through heat shrinkage.