JP2580665Y2 - Pumping tube for squeeze pump - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hose used for pumping a slurry, and more particularly to a pumping tube used for a squeeze pump for pumping a large amount of ready-mixed concrete at a high pressure.

[0002]

2. Description of the Related Art Originally, a pumping tube composed of an inner layer rubber, a reinforcing fiber layer and an outer layer rubber is housed in a pump case in a curved state, and is strongly pressed and slid by a roller rolling on the curved inside. It sucks and discharges a slurry-like fluid such as ready-mixed concrete into a pump-pink tube, and receives extremely severe operation.

[0003] The service life of this type of pumping tube is the normal pressure and flow rate (generally 15 kgf / cm ² , 2
Under −5 m / s), it is ideal that the inner rubber is finished in a state of being uniformly worn in each part. Therefore, the judgment of the time for periodic replacement of the tube is mainly considered by the wear of the inner rubber.

In the case where the slurry concentration is low and the particle size of the mixed aggregate is relatively fine, there is no problem. However, for example, aggregate such as crushed stone having a sharp shape is contained in ready-mixed concrete. In such a case, the inner layer rubber was broken by the aggregate, and the tube itself became unusable at an unexpected time, and it was necessary to replace the tube early. As mentioned above, when the tube is crushed by the roller during its operation, it is only temporary that this aggregate penetrates the inner rubber and reaches the reinforcing fiber layer. This causes early damage, such as impairing the properties, and significantly shortens the service life.

Further, the inner layer rubber of the pumping tube is exposed to particularly large frictional wear because a fluid such as ready-mixed concrete moves while rubbing the inner surface at high pressure and high speed. This kind of friction and wear is generally said to be proportional to the 2-3 power of the flow velocity, and the life thereof is sometimes reduced to 1/2/3 as compared with the case where the same flow rate is pumped at a low pressure and a low speed. In many cases, this effect was also hard to ignore.

Conventionally, as a measure against such a problem, an attempt has been made to increase the thickness of the inner rubber layer or to use rubber having higher strength. However, the former method increases the cost and thickness of the pumping tube. There is a limit to the wall thickness, such as an increase in the force (roller driving torque) that pushes out the meat, and the latter method does not necessarily improve the physical properties of the rubber itself because it is in a very limited range. It is difficult to obtain the right material, and a more effective solution has been strongly desired.

[0007]

SUMMARY OF THE INVENTION The present invention is intended to provide a method for prematurely damaging an inner layer rubber due to the presence of hard mixed concrete having a sharp shape in a slurry even when the raw concrete is pumped. It is an object of the present invention to provide a pumping tube for a squeeze-type pressure-feed pump that can minimize a reduction in life caused by high-speed fluid wear without increasing the thickness of the inner rubber layer.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, an organic short fiber of a specific size has been added to a commonly used base compound for an inner rubber layer. Was added, and it was found that the above object could be achieved by forming the inner layer rubber of the pumping tube using the short fiber composite rubber in which the short fibers were arranged in a certain direction, and completed the present invention. Was.

That is, the present invention relates to a cylindrical rubber tube having a three-layer structure of an inner layer rubber, a reinforcing fiber layer and an outer layer rubber set in a pumping unit of a pumping tube for a squeeze-type pump. As a rubber member constituting a part thereof, organic short fibers having a fiber diameter of 20 μ or less are mixed and buried so as to be arranged in a fixed direction in a range of 0.5 to 8 parts by weight per 100 parts by weight of a base compound for an inner layer rubber. Squeeze-type pumping wherein the inner layer rubber is constituted by using a fiber composite rubber and arranging the organic short fibers in the short fiber composite rubber in the longitudinal direction of the pumping tube. The gist is a pumping tube for a pump.

The base compound for the inner layer rubber used in the present invention is not particularly limited, and any compound conventionally known in this field can be used, for example, in terms of abrasion resistance, water resistance, and processability. Excellent natural rubber (NR), SBR or a blended composition of NR and BR and / or SBR can be exemplified.

The material of the organic short fibers to be mixed into these base compounds is a fiber material used as reinforcing fibers for tires, belts and the like, and is not particularly limited as long as the fiber diameter is 20 μm or less. Fibers, aromatic polyamide fibers, nylon fibers, polyester fibers and the like can be exemplified. Among them, carbon fiber and aromatic polyamide fiber have high heat resistance and high strength, so each 25 kg
/ Cm ² , especially suitable for tubes under high pressure operating conditions exceeding 20 kg / cm ² . On the other hand, nylon fibers and polyester fibers are inferior in both heat resistance and strength to the former two, but function well under general operating conditions (pressure 15 kg / cm ² ), are low in cost, and are flexible. It is particularly suitable when used in a pump case having a curved diameter.

The fiber diameter of the organic short fibers is required to be as small as 20 μm or less from the viewpoints of dispersibility in a rubber matrix, reinforcing properties, and compressive deformation properties of an embedded tube. By the way, the diameter of aramid fiber available as a commercial product is 1
2μ. As described above, each fiber material is usually used alone, but if necessary, these fiber materials can be used in combination.

Further, the organic short fiber has at least 3
It is preferable that 0% or more, preferably 50% or more, is composed of fibers having a fiber length of 3 to 25 mm. This means that, for the resistance of the aggregate to piercing and biting into the inner layer rubber, there is a fiber length that functions most effectively according to the following relationship, that is, the size of the aggregate,
Aggregates usually used such as crushed stone, the aggregate diameter leading to the early damage of the tube is in the range of 15-30mm, therefore, if the fiber length is less than 3mm or more than 25mm, the effect for the purpose is low, In addition, the longer the length exceeds 25 mm, the more difficult it becomes to disperse and mix the rubber uniformly. Therefore, if the size of the aggregate in the ready-mixed concrete to be pumped can be specified in advance,
It is desirable to select and prepare short fibers having an optimum fiber length according to the size of the aggregate. Aggregate diameter Optimal fiber length 15mm… 3-6mm 20mm… 9-12mm 30mm… 15-25mm

The mixing amount of the organic short fibers as described above is adjusted in the range of 0.5 to 8 parts by weight per 100 parts by weight of the base compound for the inner layer rubber, depending on the designed thickness of the inner layer rubber. For example, if you want to reduce the design thickness, mix 6-8 parts by weight,
On the other hand, when it can be designed to be relatively thick, it is also possible to reduce 0.5 to 2 parts by weight and its mixing amount. However, mixing of 8 parts by weight or more is not preferable because other properties other than the damage resistance and wear resistance to the aggregate are reduced and the function as a pumping tube is impaired.

Further, the present invention is characterized in that the arrangement direction of the organic short fibers is oriented toward the longitudinal direction of the pumping tube to constitute the inner layer rubber. Such an array structure of fibers improves resistance to damage by aggregates and high-speed fluid abrasion without sacrificing required performance such as bending properties, bending crack resistance, and heat generation deterioration resistance as a pumping tube. Is important. As a method of arranging the short fibers in the longitudinal direction of the tube, a mixture of the base compound for the inner layer rubber and the short fibers is extruded and coated on an iron mandrel by an extruder, or the mixture is sheet-shaped by a calender. , And the direction of arrangement is coated in the direction of the axis of the iron mandrel.

These short fiber compound rubbers are disposed over the entire length of the inner layer rubber constituting the pumping tube, or
It may be arranged only in a part of the inner layer rubber, for example, only in a range where the roller is exposed to sliding contact with the roller when the pressure feeding unit is operated.

[0017]

The pumping tube for a squeeze-type pump according to the present invention is constructed by arranging the short fiber composite rubber as described above in the inner layer rubber, so that inferior fresh concrete containing a sharp aggregate is pumped. In this case as well, it is possible to effectively prevent a reduction in the life of the tube caused by piercing of the aggregate into the inner layer rubber or early damage to the inner wall of the tube due to a cut.

Further, the fact that the arrangement direction of the organic short fibers and the flow direction of the aggregate are the same is advantageous in reducing the sliding friction coefficient of the aggregate on the inner surface of the inner rubber. The scraping force is reduced and the amount of wear is reduced. This has a particularly pronounced effect on high-speed fluid wear on the outlet side.

[0019]

Next, the present invention will be described in detail based on embodiments.

Example 1-3 Short fiber compounded rubber having the compounded composition shown in Table 1 was prepared by roll mixing, and then each compounded rubber was rolled into a sheet using a calender. To form an inner rubber layer, and then successively stack a reinforcing fiber layer and an outer rubber layer thereon in a conventional manner, and then vulcanize the laminate to obtain a squeeze-type pump having a size as described below. Pumping tube was prepared. Tube diameter: 100 mm Thickness of inner rubber layer: 10 mm Thickness of reinforcing fiber layer: 4 mm Thickness of outer rubber layer: 2 mm FIG. 1 is a schematic cross-sectional view of the pumping tube in the axial direction. In FIG. The fibers 5 are reinforcing fiber layers, and 6 is an outer rubber layer.

[0021]

[Table 1]

The aramid staple fiber, nylon staple fiber and polyester staple fiber used in these examples were all made up of 75% of fibers having a fiber diameter of 12 μm and a fiber length of 3 to 25 mm.
Organic short fibers contained.

Next, in order to evaluate the durability performance of these tubes, they were set in a pressure feeding unit as shown in FIG.
A continuous pumping test of ready-mixed concrete was performed. Table 2 shows the results
Are shown together with a comparative example (one using a base compound for the inner layer containing no short fiber). The operating conditions of the pressure feeding unit in this case were as follows. Central curvature radius (R) ... 600 mm number of revolutions of the diameter ... 400 mm Rotor rubber rollers ... 35 RPM discharge pressure ... 30kg / cm ² fluid ... mixed concrete containing aggregate ranging of about 10-30mm

[0024]

[Table 2]

From Table 2, it can be seen that the use of the short fiber composite rubber for the inner layer rubber gives the nylon fiber and the polyester fiber more than twice the durability and the aramid fiber at least three times the durability as compared with the conventional one. It is recognized that it can be done.

FIG. 2-6 is a schematic view of a main part for explaining the operation of such a short fiber composite rubber.
The ready-mixed concrete 8 poured into the tube 1 is fed by pressure sliding of two rubber rollers 9. At this time, as shown in FIG. 3, the aggregate 10 in the ready-mixed concrete is dragged by the roller 9 toward the outlet of the tube while being pressed against the inner wall of the inner rubber 2 to damage the inner rubber. In this case, in the conventional inner layer rubber, the pressed depth H of the aggregate is directly cut as shown in FIG. 4, and the inner layer rubber 2 'of the pumping tube is damaged.

On the other hand, as shown in FIG. 5, the pressed depth h is h << H due to the effect of the oriented short fibers, and even if the aggregate moves in the y direction in FIGS. The resulting cut is extremely shallow. In addition, the y direction is the longitudinal direction of the tube, that is, the direction in which the short fibers are arranged, and the strength is large and the elongation is small compared to the x direction. It seems to be.

[0028]

[Effects of the Invention] The pumping tube for a squeeze-type pressure pump according to the present invention has a required bending property for the tube.
It is possible to effectively prevent early damage due to aggregates and shortening of life caused by high-speed fluid wear without hindering various functions such as compression fatigue resistance and heat generation deterioration resistance.
In addition, the short fiber composite rubber used as the inner layer rubber is based on a conventionally used general compounded rubber,
Since it is prepared by mixing a relatively small amount of organic short fibers by a usual method, it has good adhesion to the reinforcing fiber layer and other materials in contact with it, and increases the thickness of the inner rubber layer. The desired purpose is achieved without cost. In particular, when heat-resistant and high-strength fibers such as aramid fibers and carbon fibers are used as short fibers, a product which can sufficiently withstand high-pressure pumping at a discharge pressure of 25 kg / cm ² or more can be obtained.

[Brief description of the drawings]

FIG. 1 is an axial sectional view of a pumping tube according to the present invention.

FIG. 2 is a schematic cross-sectional view showing an operation state of the pressure feeding unit.

FIG. 3 is an enlarged view of a portion A in FIG. 2;

FIG. 4 is an explanatory diagram of internal damage in a conventional tube.

FIG. 5 is an explanatory view of the tube of the present invention.

FIG. 6 is a perspective view of the pumping tube of the present invention.

[Explanation of symbols]

 1: Pumping tube (rubber tube) 2, 2 ': Inner layer rubber 3: Organic short fiber 4: Rubber matrix 5: Reinforcing fiber layer 6: Outer layer rubber 7: Compression unit 8: Fresh concrete 9: Rubber roller 10: Aggregate

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Katsushi Tanaka 2 Tomoe, Bessho-cho, Miki-shi, Hyogo Far East Development Kogyo Co., Ltd. Miki Plant Park (56) References Open-ended 4-84780 (JP, U) Opened Showa 47-29704 (JP, U) Actually open Showa 49-87962 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F04C 5/00 341 F04C 13/00 F16L 11/08

Claims (3)

(57) [Scope of request for utility model registration] An inner rubber, a reinforcing fiber layer, and an outer rubber set in a pumping unit of a squeeze-type pump.
In a cylindrical rubber tube having a layer structure, an organic short fiber having a fiber diameter of 20 μ or less is used as a rubber member constituting the entire length of the inner layer rubber or a part of the inner layer rubber. In the range of 8 parts by weight,
The inner layer rubber is formed by using short fiber composite rubber mixed and buried so as to be arranged in a certain direction, and arranging the organic short fibers in the short fiber composite rubber in the longitudinal direction of the pumping tube. A pumping tube for a squeeze-type pressure feed pump, which is characterized in that: 2. The pumping tube for a squeeze type pump according to claim 1, wherein the organic short fibers are short fibers made of carbon fibers, aromatic polyamide fibers, nylon fibers or polyester fibers or a mixture of these short fibers. 3. The organic short fiber according to claim 1, wherein at least 50% or more of the organic short fiber is a fiber having a fiber length of 3 to 25 mm.
A pumping tube for a squeeze-type pressure pump according to the above description.