JPH0420111B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a bellows hose for supernatant liquid discharge, and in particular has a constant tensile property and a linear relationship between elongation and tensile force. The present invention relates to a method for manufacturing a bellows hose for discharging supernatant liquid, which requires the following.

[Conventional technology]

The bellows hose for supernatant liquid discharge is used, for example, as a bellows hose for flotation adjustment in batch-type activated sludge treatment equipment, and is designed to be able to expand and contract in a manner that follows even slight fluctuations in the floating state of the drainage trough. In order to do this, various manufacturing methods have been devised.

A method for manufacturing such a bellows hose is, for example, to form a cylindrical hose by sequentially overlapping and winding an inner layer rubber, an intermediate cord reinforcing layer, and an outer layer rubber on a mandrel having an uneven surface in which circumferential grooves and circumferential protrusions are alternately formed. A hose molded body is formed into a shape that matches the concave and convex surface of the mandrel by tightening with a string-like body at a position corresponding to the concave surface of the mandrel, and then vulcanized (Japanese Patent Laid-Open No. 57-204386, etc.) )
can be given.

FIGS. 4a and 4b are explanatory diagrams showing the main steps of the method for manufacturing such a bellows hose. In the figure, a molded hose consisting of a reinforcing layer 1, an inner rubber layer 5, and an outer rubber layer 6 is formed on a mandrel 4 having an uneven surface, and is tightened with a string-like member 7 at a position corresponding to the concave surface of the mandrel 4. .

On the other hand, as shown in FIG. 5, after molding and vulcanizing a rubber cylinder 1 having a reinforcing layer 2 in the middle, a rigid ring 3 having an outer diameter slightly larger than the inner diameter of this cylinder 1 is attached to the cylinder. There is a method in which the rigid rings 3 are inserted into the ring 1 at equal intervals and sewn using a thread 4 so that the rigid rings 3 do not fall off.

[Problem that the invention seeks to solve]

However, in this conventional manufacturing method for bellows hoses, fluid leaks from the sewn parts of the produced bellows hoses, the entire hose becomes hard due to vulcanization, and the relationship between elongation and tensile force varies over a wide range. There was a fundamental problem in that it was not possible to manufacture a linear bellows hose.

FIG. 6 is a diagram showing the relationship between tensile force and elongation of a bellows hose manufactured by a conventional manufacturing method. In the figure, it can be seen that the range in which the relationship between tensile force and elongation is linear is extremely narrow.

The object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a bellows hose for discharging supernatant liquid, which has a wide range of elastic deformation, can smoothly respond to changes in tensile force, and does not cause fluid leakage. The purpose is to provide a manufacturing method.

[Means for solving problems]

In order to achieve the above object, the method for manufacturing a bellows hose for supernatant liquid discharge of the present invention involves forming a rubber cylinder of uniform thickness with a reinforcing layer in the middle on a mandrel, and vulcanizing the cylinder. After that, the mandrel is removed, a plurality of rigid rings having an outer diameter 10 to 20% larger than the inner diameter of the cylinder are inserted into the cylinder, and then the cylinder is further heat-treated to be fixed. .

In the present invention, when the rubber cylinder is vulcanized, it is preferable to wrap the outer surface of the rubber cylinder with cloth or the like. This can prevent bubbles from forming within the rubber. Furthermore, when removing the mandrel from the rubber cylinder, it is preferable to blow compressed air or the like between the mandrel and the rubber cylinder.
Thereby, the mandrel can be easily removed.

In the present invention, the outer diameter of the rigid ring varies somewhat depending on the material and wall thickness of the rubber cylinder and the reinforcing layer, but it is preferably 10 to 20% larger than the inner diameter of the rubber cylinder. If the outer diameter of the rigid ring is less than 10% larger than the inner diameter of the rubber cylinder, it may fall off during manufacturing, and if it exceeds 20%, it will be difficult to insert the rigid ring into the cylinder. This results in extremely poor manufacturing efficiency.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

FIGS. 1 and 2 are cross-sectional views showing the manufacturing process of a bellows hose for discharging supernatant liquid, which is an embodiment of the present invention. In FIG. 1, the mandrel 11
A rubber cylinder 10 having a uniform wall thickness and having a fiber reinforcing layer 13 between the inner rubber 12 and the outer rubber 14 is molded thereon. At this time, both ends of the Goss cylindrical body 10 can be formed into a predetermined shape depending on the use of the bellows hose for discharging the supernatant liquid. Next, after this Goss cylinder 10 is vulcanized under predetermined conditions, the mandrel 11 is extracted from the vulcanized Goss cylinder 10. Subsequently, rigid rings 15 having an outer diameter 10 to 20% larger than the inner diameter of the rubber cylinder 10 are inserted into the rubber cylinder 10 at predetermined intervals. In this case, as shown in FIG. 2, the rigid ring 15 is inserted almost parallel to the axis of the rubber cylinder 10, a part of it is brought into contact with the inner surface of the cylinder at a predetermined position, and the opposite part is strongly pressed. Thereby, the rigid ring 15 can be fixed in a predetermined position on the rubber cylinder 10. Next, in this state, the rubber cylinder 10 is heat-treated under predetermined conditions to soften the rubber cylinder 10 between the rigid rings 15, 15, and then cooled and fixed. The shape of is stabilized.

FIG. 3 is a diagram showing a cross section of the bellows hose obtained in this example. In the figure, cylinder 1
Rigid rings 15 are inserted at equal intervals inside 0,
A bellows hose for discharging supernatant liquid is shown in which the cylindrical body 10 between the rigid rings 15 is made flexible.

According to this embodiment, from the inner diameter of the rubber cylinder 10
By using the rigid ring 15 having a 10 to 20% larger outer diameter, the rigid ring 15 is equally compressed by the rubber cylinder 10 from the front and back, so there is no risk of the rigid ring 15 falling off, and it is easy to handle. It becomes easier. In addition, since the rubber cylinder 10 is integrally molded, there is no fear of fluid leakage.

Furthermore, by heat treatment after vulcanization molding and ring insertion, the rubber cylindrical body 10 becomes flexible, and in combination with the effect of the rigid rings arranged at equal intervals,
A bellows hose with an extremely wide linear expansion and contraction range can be obtained.

This bellows hose for supernatant liquid discharge has a wide range of elongation, so it can be used in fields where the relationship between elongation and tensile force is required to be linear, such as a bellows hose for flotation adjustment in batch-type activated sludge treatment equipment. Suitably used.

In this embodiment, the materials of the inner rubber 12, outer rubber 14, and rigid ring 15 that constitute the rubber cylinder 10 can be appropriately selected depending on the usage conditions of the bellows hose, such as temperature and type of fluid. Further, the shapes of the rubber cylinder 10 and the rigid ring 15 are usually circular in cross section, but they can also be elliptical or rectangular if necessary.

Next, specific examples of the present invention will be described.

Example 1 A 2.5 mm thick cylinder made of a chloroprene rubber compound with polyester fibers inserted in the middle was molded onto a 10 inch diameter mandrel and heated to 155°C.
After 40 minutes of vulcanization and water cooling, a stainless steel ring with an outer diameter of 12 inches was inserted and heat treated at 150℃ for 10 minutes, resulting in a bellows hose for draining supernatant fluid with a softened rubber cylinder. It was done.

Comparative Example 1 A bellows hose was produced in the same manner as in Example 1 except that no heat treatment was performed after inserting the stainless steel ring. A bellows hose with a hard cylindrical body and poor elasticity was obtained.

The strength and elongation characteristics of the bellows hoses obtained in Example 1 and Comparative Example 1 were measured, and the results were compared.
Shown in the figure. In the figure, it can be seen that the bellows hose of Example 1 has a wider elongation range of elastic deformation and significantly higher tensile strength than Comparative Example 1.

FIG. 8 is an explanatory diagram when the bellows hose for supernatant discharge obtained in Example 1 is used as a bellows hose for flotation adjustment in an activated sludge treatment apparatus. In the figure, a bellows hose 22 for supernatant liquid discharge is connected below the trough 21 and serves as a discharge flow path for the collected supernatant liquid. Such a bellows hose for flotation adjustment is required to be able to expand and contract quickly following the floating state of the trough 21, but the bellows hose for draining supernatant liquid obtained in Example 1 has a relationship between elongation and tensile force. is linear and can be suitably used in such fields.

〔Effect of the invention〕

According to the present invention, after the independent rigid rings are attached to the rubber cylinder, the cylinder is further heat-treated, thereby imparting flexibility to the cylinder between the rigid rings, and having good tensile properties and elongation. A bellows hose for supernatant liquid discharge with a wide width can be obtained.

[Brief explanation of drawings]

FIGS. 1 and 2 are explanatory diagrams showing the steps of a method for manufacturing a bellows hose for draining supernatant liquid, which is an embodiment of the present invention, and FIG. 3 is an illustration of a bellows hose manufactured according to an embodiment of the present invention. Figures 4a and 4b are explanatory diagrams showing the manufacturing process of a conventional bellows hose, Figure 5 is a diagram showing the structure of a bellows hose manufactured by another conventional technique, and Figure 6 is a diagram showing the structure. , a diagram showing the tensile properties of the conventional bellows hose, FIG. 7 is a diagram showing a comparison of the tensile properties of the bellows hose obtained in Example 1 and Comparative Example 1, and FIG. 8 is a diagram showing the tensile properties of the bellows hose obtained in Example 1. It is a figure which shows the usage state of the bellows hose. 10...Rubber cylinder, 11...Mandrel, 1
2... Inner rubber, 13... Fiber reinforcement layer, 14... Outer rubber, 15... Rigid ring.

Claims (1)

[Claims] 1. A rubber cylinder of uniform thickness with a reinforcing layer provided in the middle is formed on a mandrel, and after vulcanizing the cylinder, the mandrel is removed, and a rubber cylinder with a diameter 10 to 20% larger than the inner diameter of the cylinder is formed inside the cylinder. A method for manufacturing a bellows hose for discharging supernatant liquid, comprising inserting a plurality of rigid rings each having an outer diameter, and then further heat-treating the cylindrical body.