JPH0318077B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a rubber hose for pressurizing fresh concrete used in construction machinery and the like. INDUSTRIAL APPLICATION This invention can be utilized for the rubber hose for the tip of ready-mixed concrete pouring which discharges ready-mixed concrete to a pouring site, or the rubber hose for connection to the steel pipe which pumps ready-mixed concrete.

[Prior Art] Rubber hoses for pressurizing fresh concrete have been known. This rubber hose for pressurizing fresh concrete generally has a relatively large inner diameter of about 75 to 200 mm. As such a rubber hose for pumping fresh concrete, one is known in which the outer circumferential surface of a cylindrical inner rubber layer forming a fluid passage is coated with a reinforcing cord layer and an outer rubber layer, respectively, in sequence. This reinforcing cord layer is for reinforcing the inner rubber layer and outer rubber layer, and a strip-shaped blind cord with a structure in which many fibers are aligned in the longitudinal direction and topped with rubber is attached to the hose shaft core. It is formed by winding the layers spirally at a winding angle of 54.5 degrees and alternately winding adjacent layers in opposite directions in the lamination direction.

If the band-shaped blind cord is wrapped at a wrapping angle of 54.5 degrees, the strength in the radial direction of the hose will be equal to the strength in the longitudinal direction, and the wrapping angle will not substantially change even if the internal pressure of the hose increases. Also, if the wrapping angle of the belt-shaped blind cord is larger than 54.5 degrees, when internal pressure is applied to the hose, the belt-shaped blind cord will turn 54.5 degrees.
It is known that the hose expands in the axial direction (longitudinal direction) and contracts in the radial direction because the hose is displaced as it approaches the angle of 54.5 degrees. It is being

By the way, in the above-mentioned rubber hose for pumping fresh concrete, since the fresh concrete is pumped, the friction of the inner rubber layer is significant, and the wear progresses to the reinforcing cord layer. This wear is difficult to detect from the outside. If the internal pressure of the hose increases when wear occurs in this way, the rubber hose will not be able to withstand the internal pressure during pumping of fresh concrete, and there is a danger that the hose will burst, the separation end will fly away, and the ready-mixed concrete will scatter. Ta. In order to suppress such complete separation, it is conceivable to form an auxiliary cord layer by wrapping a band-shaped blind cord around the outer peripheral surface of the reinforcing cord layer at a wrapping angle larger than 54.5 degrees without any gaps. However, if the auxiliary cord layer is wrapped around the entire outer peripheral surface of the reinforcing cord layer without any gaps, the rigidity of the rubber hose for pumping fresh concrete increases and the flexibility of the hose decreases.

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned circumstances, and its purpose is to wrap a belt-shaped blind cord between the reinforcing cord layer and the outer rubber layer at an angle of 65 to 80. By forming an auxiliary cord layer by wrapping the hose with a predetermined gap, even if the hose ruptures, the rupture will occur in the area of the gap, and this will prevent the reinforcing cord layer from rupturing in the event of a rupture. To provide a rubber hose for pressurizing ready-mixed concrete, which leaves an auxiliary cord layer even when the concrete is removed, minimizes separation of the hose, improves safety, and further ensures flexibility of the hose due to the above-mentioned gap.

[Means for Solving the Problems] The rubber hose for pumping ready-mixed concrete according to the present invention includes a cylindrical inner rubber layer, an outer rubber layer provided on the outer periphery of the inner rubber layer, an inner rubber layer and the outer rubber layer. In a rubber hose for pumping ready-mixed concrete, the hose has a cord layer in which a band-shaped blind cord is spirally wound between the cord layer and the cord layer, in which the band-shaped blind cord is alternately wound in opposite directions to the shaft center on the outer periphery of the inner rubber layer. 54, a reinforcing cord layer that is wrapped uniformly at a winding angle close to 5 degrees without leaving any gaps between adjacent strip-shaped blind cords, and between the reinforcing cord layer and the outer rubber layer. an auxiliary cord layer in which a belt-shaped blind cord is wound at a winding angle of 65 to 80 degrees with respect to the axis, and then wound at a predetermined pitch with a predetermined interval between adjacent belt-shaped blind cords; It is characterized by being composed of.

In the rubber hose according to the present invention, the band-shaped blind cord of the reinforcing cord layer is wound at an angle of approximately 54.5 degrees with respect to the shaft core. The reinforcing cord layer can be constructed by spirally winding a strip-shaped blind cord as in the conventional case. Generally, 2 to 4 reinforcing cord layers are laminated, but
The winding direction of each layer adjacent to each other in the stacking direction is alternately changed. Here, the belt-shaped blind cord refers to a belt-shaped or tape-shaped cord in which a large number of fibers are aligned in the longitudinal direction, bound with leno thread, etc., and topped with rubber.

In addition, the belt-shaped blind cord forming the auxiliary cord layer is wound in a spiral shape at a predetermined pitch with a winding angle (65 degrees to 80 degrees) larger than 54.5 degrees with respect to the axis and with a constant gap. wrapped around it. This winding angle is especially 65° with respect to the hose axis.
About 75 degrees is preferable.

The auxiliary cord layer can be constructed by spirally winding a belt-shaped blind cord at a predetermined pitch while providing a predetermined gap. This gap is necessary to ensure the flexibility of the rubber hose for pumping fresh concrete according to the present invention. The width of the belt-shaped blind cord forming the auxiliary cord layer is desirably set in consideration of the flexibility and strength of the rubber hose, and is generally preferably about 50 to 200 mm.

The winding angle of the belt-shaped blind cord constituting the auxiliary cord layer is 65 to 80 degrees, which is larger than the winding angle (54.5 degrees) of the belt-shaped blind cord constituting the reinforcing cord layer. The reason is as follows. In other words, the larger the wrapping angle, the easier it is to ensure the flexibility of the rubber hose.Also, since the auxiliary cord layer also receives the internal pressure of the hose in the same way as the reinforcing cord layer, the wrapping angle of the auxiliary cord layer is reinforced. This is because unless the winding angle is at least 10 degrees greater than the winding angle of the cord layer, when the reinforcing cord layer is cut, the auxiliary cord layer will also be cut at the same time. On the other hand, if the winding angle of the auxiliary cord layer is made too large, for example exceeding 80 degrees, it becomes difficult to form the above-mentioned gap, and the auxiliary cord layer ends up being wrapped around almost the entire outer circumferential surface of the reinforcing cord layer. Become.

In addition, the elongation rate of the strip-shaped blind cord that makes up the auxiliary cord layer is approximately the same as the elongation rate of the strip-shaped blind cord that makes up the reinforcing cord layer, in terms of ensuring the elongation of the auxiliary cord layer and suppressing the breakage of the auxiliary cord layer. Preferably, they are equal or greater.

In the rubber hose according to the present invention, an intermediate rubber layer may or may not be provided between the outer rubber layer and the inner rubber layer.

The inner rubber layer and outer rubber layer constituting the rubber hose of the present invention can be the same as those used in conventional rubber hoses for pumping fresh concrete.

[Function] In the rubber hose according to the present invention, since the band-shaped blind cord constituting the reinforcing cord layer has a wrapping angle of 54.5 degrees, the strength in the radial direction and the strength in the axial direction are substantially the same, and therefore the strength of the hose is When the internal pressure increases, the reinforcing cord layer tends to expand while maintaining the wrapping angle of 54.5 degrees, so that an increase in pressure immediately acts on the reinforcing cord layer.

On the other hand, the band-shaped blind cord that makes up the auxiliary cord layer has a wrapping angle of 60 to 80 degrees, so when the internal pressure of the hose increases, it will be displaced to a wrapping angle of 54.5 degrees, and this displacement will reduce the overpressure. It can be absorbed. Therefore, in the present invention, when the hose ruptures due to overpressure, the reinforcing cord layer ruptures first.
Furthermore, the breakage point is in a gap area (corresponding to L in FIG. 1) where the auxiliary cord layer is not laminated in the reinforcing cord layer. This is because the strength of the rubber hose is lower in the gap area than in other parts.
Note that if the reinforcing cord layer ruptures and the rubber hose ruptures, the overpressure is released, so the auxiliary cord layer remains.

[Effects of the Invention] In the rubber hose for pressurizing fresh concrete according to the present invention, even if the rubber hose is split in the longitudinal direction and the reinforcing cord layer is broken, the auxiliary cord layer remains as described above. Therefore, the split rubber hose is connected by the auxiliary cord layer, and the rubber hose can be completely separated and scattering can be minimized, improving safety.

Further, in the rubber hose for pressurizing fresh concrete according to the present invention, the auxiliary cord layer is formed by winding the band-shaped blind cord while forming a predetermined gap, so that the flexibility of the rubber hose can be ensured by the gap. Therefore, it is convenient for the rubber hose for pressurizing fresh concrete according to the present invention to be delivered to a desired location.

[Example] As shown in Fig. 1, the rubber hose according to this example has a cylindrical inner rubber layer 1 with an inner diameter of 105 mm forming a fluid passage, and a diameter of 54,5 mm with respect to the hose axis X.
The reinforcing cord layer 2 is wrapped around the outer circumferential surface of the inner rubber layer 1 at a winding angle close to the angle β1 shown in FIG. and on the outer peripheral surface of the intermediate rubber layer 3.
54, the reinforcing cord layer 4 is wrapped at a winding angle close to 5 degrees (β2 shown in Figure 1), and the hose is wrapped around the outer peripheral surface of the reinforcing cord layer 4 at a winding angle of 70 degrees (β2 shown in Figure 1). It consists of an auxiliary cord layer 4 wound at an angle α) with respect to the axis X, and an outer rubber layer 6 covering the outer peripheral surface of the auxiliary cord layer 4.

Here, the reinforcing cord layers 2 and 4 are for ensuring the pressure resistance of the rubber hose for pumping fresh concrete, and are spirally wound in opposite directions as shown in FIG. The reinforcing cord layers 2 and 4 are made of a belt-like blind cord having a structure in which a large number of polyester fibers are aligned in the longitudinal direction, bound with leno threads, and topped with rubber.
It is constructed by winding this belt-shaped blind cord in a spiral shape without any gaps. In addition,
The polyester fiber used had a diameter of 0.8 mm and an elongation rate of 23%.

The auxiliary cord layer 4 uses a belt-shaped blind cord having a structure in which a large number of nylon fibers are aligned in the longitudinal direction, restrained with leno thread, and topped with rubber. It is constructed by winding it spirally at a predetermined pitch so as to form a gap L. Here, the winding angle of the belt-shaped blind cord (angle α shown in Fig. 1) is 54, as described above.
70 degrees is larger than 5 degrees. The nylon fiber used had a diameter of 0.8 mm and an elongation rate of 30%.

In this example, the width dimension (L1 shown in Fig. 1) of the belt-shaped blind cord forming the auxiliary cord layer 5 is 60 mm.
The width L of the gap during spiral winding was set to 70 mm.

In order to check the bursting pressure of the rubber hose for pumping fresh concrete according to this example, both ends of the rubber hose were closed;
Internal pressure was applied to the rubber hose, increasing the internal pressure and causing it to burst. The bursting pressure value of the rubber hose according to this example was 112 Kgf/cm ² .

In the rubber hose for pressurizing fresh concrete according to this embodiment,
When the rupture occurred, the inner rubber layer 1, the reinforcing cord layers 2 and 4, and the intermediate rubber layer 3 were ruptured in the area of the gap L where the auxiliary cord layer 5 was not present, but as schematically illustrated in FIG. The auxiliary cord layer 5 remained continuously. Therefore, the auxiliary cord layer 5 can prevent the rubber hose from completely separating and scattering, and the distance L3 between the openings at the fracture site (FIG. 2) can also be kept small, which is advantageous in terms of ensuring safety.

In the rubber hose for pressurizing fresh concrete according to this embodiment,
Since the auxiliary cord layer 5 has a gap L as shown in FIG. 1, the flexibility of the rubber hose can be ensured.

[Brief explanation of the drawing]

FIG. 1 is a side view of the main parts of the rubber hose according to the present embodiment, with the outer rubber layer removed. FIG. 2 is an explanatory diagram schematically showing a ruptured state. In the figure, 1 is an inner rubber layer, 2 and 4 are reinforcing cord layers, 3 is an intermediate rubber layer, 5 is an auxiliary cord layer, and 6 is an outer rubber layer.

Claims (1)

[Scope of Claims] 1. A cylindrical inner rubber layer, an outer rubber layer provided around the outer periphery of the inner rubber layer, and a belt-shaped blind cord arranged in a spiral shape between the inner rubber layer and the outer rubber layer. In a rubber hose for pumping ready-mixed concrete, the cord layer includes strip-shaped blind cords that are alternately wound in opposite directions on the outer periphery of the inner rubber layer at a wrapping angle close to 54.5 degrees with respect to the shaft center. , a reinforcing cord layer that is wound uniformly without leaving a gap between adjacent strip-shaped blind cords, and a strip-shaped blind cord is placed between the reinforcing cord layer and the outer rubber layer with respect to the axis. An auxiliary cord layer is wound at a winding angle of 65 to 80 degrees and is wound at a prescribed pitch between adjacent belt-shaped blind cords at a prescribed interval. Rubber hose for pumping fresh concrete. 2. The rubber hose for pumping ready-mixed concrete according to claim 1, wherein the elongation rate of the belt-shaped blind cords constituting the auxiliary cord layer is approximately equal to or greater than the elongation rate of the belt-shaped blind cords constituting the reinforcing cord layer.