JPH0728476Y2 - Rubber hose connection fitting - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a connection fitting that is fixed to the end of a rubber hose, and more particularly to a connection fitting that can be used for estimating the life of a rubber hose to which the connection fitting is fixed.

[Conventional technology]

2. Description of the Related Art Conventionally, connecting fittings are fixed to the ends of rubber hoses, and are used for the purpose of connecting rubber hoses to each other and connecting the rubber hoses to devices such as pumps.

Some rubber hoses are used for pumping fluids containing solids, such as hose for pouring ready-mixed concrete that is connected to a piston type concrete pump to pump fresh concrete to near the pouring site, and underground work and ground work that is connected to a muddy water pump. There is a mud hose for draining muddy water from the site, or a rubber hose for pumping fluid containing cement at ultra high pressure to a multi-pipe rod that is drilled in the ground by a new ground improvement method called RJP method.

These rubber hoses transfer fluids containing solids such as cement, sand, and gravel at high pressure, so use rubber materials with excellent wear resistance, or use a reinforcing material such as wire or canvas inside spirally. Although an attempt is made to increase the wear resistance and the pressure resistance by providing a reinforcing layer on the inner surface, the inner peripheral surface is still worn so that the wall thickness becomes thin as the wear progresses.

However, such wear of the inner peripheral surface of the rubber hose cannot be confirmed from the outside, and it is difficult to judge to what extent the wear has progressed by looking at the inner peripheral surface of the rubber hose from the end of the connection fitting at the end of the work. . Therefore, if you continue to use it without noticing the progress of thinning, the inner rubber layer inside the reinforcing layer will disappear, or it will become extremely thin and the rubber hose will burst or the rubber hose will fall out of the connection fitting. This will result in

Therefore, in the past, regarding rubber hoses used to pump fluid containing solids such as ready-mixed concrete hoses, safety was based on the usage time until the rubber hose burst at the work site in the past or the pumped volume of fluid. In view of this, the life of the pressure limit of the hose was set considerably earlier than this cumulative use time or cumulative pumped volume, and thereafter, the same rubber hose was replaced with a new rubber hose before reaching the aforementioned life.

However, this method was uneconomical as a result, in many cases, the rubber hose still usable was replaced and discarded.
On the other hand, if the product is used for near the cumulative operating time or cumulative pumping volume that is empirically estimated as the service life, there is a possibility that a situation such as rupture may occur earlier than expected, which is extremely dangerous. Due to the different prediction of life, there are not a few cases where a hose for placing ready-mixed concrete, a hose for mud, etc. ruptured at the construction site, resulting in a major disaster.

Even if the same type of rubber hose is used, the progress of wear is different due to the difference in the composition of the fluid or the difference in the solids contained in the fluid, so when using the same rubber hose for the pressure feed of various fluids such as ready-mixed concrete and mortar. However, there is a drawback that the life management by the above method becomes impossible.

[Problems to be solved by the device]

In view of the above conventional circumstances, the present invention provides a rubber hose used for pressure-feeding a fluid containing a solid substance, which is used at a construction site without being constrained by the type of the fluid, and has a substantially accurate life of the pressure limit of the rubber hose. The purpose is to estimate.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention shall estimate the life of the rubber hose by utilizing a fitting that wears together with the rubber hose. However, in the fitting of the present invention, the end of the rubber hose used for pumping the fluid containing solid matter In a substantially cylindrical connecting fitting that is fixedly attached to a rubber hose, the cylindrical protruding portion is made of the same material as the connecting fitting main body, which is provided by projecting in the axial direction with the inner peripheral surface flush with the end portion on the insertion side into the rubber hose. When the cylindrical protruding portion is thinner than the effective thickness of the connection fitting body and the inner surface rubber layer of the rubber hose is worn by the fluid and is near the life of the pressure limit of the rubber hose, it is worn together with the inner surface rubber layer. It is characterized in that it is formed to a thickness that disappears.

[Action]

When pumping a fluid containing solid matter, the inner peripheral surface of the connecting metal fitting fixed to the end of the rubber hose also wears at the same time as the inner peripheral surface of the rubber hose wears.In consideration of this wear, the effective thickness of the connecting metal fitting is generally the rubber hose. Is thick enough to remain even if it wears out and reaches the end of its life.

Since the connecting fitting of the present invention is formed with a cylindrical protrusion that is thinner than the effective thickness, when the connecting fitting is fixed to the rubber hose and is actually used, the rubber hose and the connecting fitting are joined together from the inner peripheral surface. It wears and at some point the thin cylindrical projection first wears off. The disappearance of the cylindrical projecting portion can be easily confirmed by visually observing or touching with a hand after the work of one day is completed.

Moreover, by checking beforehand the relative degree of wear of the inner rubber layer of the rubber hose and the connection fitting according to the material, the time when the remaining thickness of the inner rubber layer becomes the minimum necessary amount due to wear ( That is, the thickness of the cylindrical protruding portion can be determined almost exactly so that the cylindrical protruding portion of the connecting fitting will wear out at the time of the life of the pressure resistance limit). In particular, if alloy steel for machine structures that is generally used as a metal fitting, such as STKM13A, is used, wear progresses to about the same level as wear resistant rubber such as natural rubber with excellent wear resistance. ,
When the cylindrical protrusion with the specified thickness disappears, the inner rubber layer of approximately the same thickness wears and disappears, and simply subtracts the minimum required remaining thickness at the end of its life from the initial thickness of the inner rubber layer. Is defined as the thickness of the cylindrical protrusion.

Actually, the safety factor is estimated in consideration of uncertain factors such as variation in wear progress, and the thickness of the cylindrical protrusion is made slightly thinner than the thickness calculated as above, and the disappearance of the cylindrical protrusion is confirmed. At that point, the rubber hose is also judged to have reached the end of its life and discarded, and a new rubber hose (with connection fittings) is replaced.

It should be noted that it is possible to use metal materials such as mild steel, hard steel, and cast steel as the material of the connection fittings, and it has been confirmed that wear progresses almost together with the inner rubber layer without causing a large step.

〔Example〕

A specific example of the connection fitting according to the present invention will be described with reference to FIGS.

The rubber hose 1 shown in FIG. 1 is a hose for placing ready-mixed concrete, and has a cylindrical shape with a length of 3 m and an inner diameter of 130.8 mm, and its layer structure is an inner rubber layer 2 made of natural rubber and having a thickness of 5.0 mm. Inner reinforcing fiber layer 3 with six layers of topped polyester canvas wrapped in a spiral, diameter 4.0 m
It consists of a wire layer 4 of m, an outer reinforcing fiber layer 5 in which a topped polyester canvas is wound twice, and an outer surface rubber layer 6 made of natural rubber and having a thickness of 2.0 mm as the outermost layer. On the inner circumference of the end of the rubber hose 1, a connecting fitting 7 for connecting to a boom extending from the pump, a driving pipe, etc., and on the outer circumference of the end, an outer ring 9 is fitted. To the same inner diameter as that of the rubber hose 1 by means of a jig.

The connecting fitting 7 is entirely made of STKM13A, and the effective thickness (D) of the main body excluding the thread portion on the outer circumference is 5.0 mm, which is the same as the inner rubber layer 2 of the rubber hose 1. The inner diameter of the connection end side of the connection fitting 7 was 130.8 mm from the beginning, but the insertion end side was initially 117 mm, and after expansion the diameter was uniformly 130.8 mm.

The connecting metal fitting 7 has a total length of 200 mm, and integrally has a cylindrical projecting portion 8 projecting 30 mm in the axial direction from the end portion on the insertion side into the rubber hose 1 so that the inner peripheral surface is flush with the cylindrical projecting portion. Part 8
The inner peripheral surface after the diameter expansion is concentric with the inner peripheral surface of the main body and has the same inner diameter (130.8 mm). Further, the thickness (d) of the cylindrical protrusion 8 is about 0.5 mm since the minimum thickness of the inner rubber layer 2 required at the life of the pressure limit is about 0.5 mm. 4.5mm, but for safety, 0.8m from the initial thickness of the inner rubber layer 2 and the effective thickness (D) of the main fitting body
Only m, which is thin, is 4.2 mm.

The rubber hose 1 to which this connecting metal fitting 7 was fixed was connected to a pump, and when fresh concrete was pressure-fed and a placement test was conducted, it was a cylinder as shown in Fig. 2 on the 218th day from the start of the test (fresh concrete cumulative pressure-fed volume 20100 m ³ ). The protrusion 8 disappeared due to wear, and it was determined that the rubber hose 1 had reached the end of its life. After that, when the same pouring test of the ready-mixed concrete was continued to confirm the life, the rubber hose 1 ruptured at the total 222th day (cumulative concrete cumulative feed volume 20500 m ³ ) four days later, and the judgment of the aforementioned life was accurate. It turns out that

As shown in FIG. 3, if the thickness of the cylindrical protruding portion 8 is made thinner stepwise from the outer peripheral side, the thin portions on the tip side disappear in order, so that the progress of wear is sequentially checked. Can be used while.

[Effect of device]

By using the connection fitting of the present invention, a rubber hose used for pressure-feeding a fluid containing solid matter, such as a hose for placing ready-mixed concrete, can be used for practically every construction fluid such as ready-mixed concrete, mortar, muddy water, etc. The life of the rubber hose can be estimated almost accurately and easily while using it for transfer.

Therefore, it is possible to accurately replace the rubber hose and it is economical, and at the same time, it is possible to prevent the occurrence of a serious situation such as the rupture of the rubber hose or the falling off of the connection fitting.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a concrete example of the connecting fitting according to the present invention fixed to the end portion of a ready-mixed concrete casting hose, and FIG. 2 is a cylindrical projecting portion due to wear of the connecting fitting of FIG. FIG. 3 is a schematic cross-sectional view at the time of disappearance, and FIG. 3 is a schematic cross-sectional view showing a cylindrical protrusion of another specific example of the connecting fitting. 1 ... Rubber hose, 2 ... Inner rubber layer 3 ... Inner reinforcing fiber layer, 4 ... Wire layer 5 ... Outer reinforcing fiber layer, 6 ... Outer rubber layer 7 ... Connecting metal fitting, 8 ... Cylindrical protrusion Part 9 ... Outer ring

Claims (1)

[Scope of utility model registration request] 1. A substantially cylindrical connecting fitting used by being fixedly attached to an end of a rubber hose used for pressure-feeding a fluid containing solid matter, the shaft having an inner peripheral surface flush with the end on the insertion side into the rubber hose. Has a cylindrical protruding portion made of the same material as that of the connecting metal fitting main body, which is thinner than the effective thickness of the connecting metal fitting main body, and the inner surface rubber layer of the rubber hose is worn by the fluid and A rubber hose connecting fitting characterized in that it is formed to a thickness such that it wears and disappears together with the inner rubber layer when it approaches the end of its pressure-resistant life.