GB2120746A

GB2120746A - Rubber tube for dredging work

Info

Publication number: GB2120746A
Application number: GB08310877A
Authority: GB
Inventors: Katsuyoshi Sumitani; Yasuo Takehara
Original assignee: Sumitomo Rubber Industries Ltd
Current assignee: Sumitomo Rubber Industries Ltd
Priority date: 1982-04-22
Filing date: 1983-04-21
Publication date: 1983-12-07
Also published as: DE3314671A1; DE3314671C2; DE3347898C2; DE3347898A1; KR840004485A; FR2525726B1; GB2120746B; GB8310877D0; KR870000042B1; FR2525726A1; NL8301421A

Abstract

A rubber tube 21 for dredging work has a tubular body 23, 24 made of rubber having a plurality of strengthening cloth layers embedded therein, and a plurality of metal rings 26 axially arranged in a suitably spaced relation and embedded in an inner peripheral surface of said tubular body. The metal rings 26 have their joined surface with the tubular body placed in parallel to the axis, and both axial ends thereof are thin in wall thickness. Thereby, the contact area between the metal ring 26 and the tubular body is increased to strengthen the bonding and to minimize peeling-off of the joined surface between both ends of the metal rings 26 and the tubular body. <IMAGE>

Description

SPECIFICATION Rubber tube for dredging work FIELD AND BACKGROUND OF THE INVEN TION The present invention relates to a construction of a rubber tube incorporated into a pipe-line for dredging work for use, and more particularly, to a rubber tube suitable for use in dredging crushed pieces of coral in a coral reef and crushed stones with acute end edges.

In a pipe-line for dredging work including a suction line and a delivery line used for dredging work in river or sea, a rubber tube having a relatively large diameter is interposed between iron pipes which are main material to impart flexibility to said lines. However, where work is performed in the coral reef or in sea or river including the crushed stones with acute end edges, crushed pieces of coral and solid particles such as crushed stones in a current of sand and earth transported under high pressure within the pipe-line violently impinge upon the inner peripheral surface of the rubber tube. Therefore, the inner peripheral surface of the rubber tube is cut and torn, and torn off by said particles, as a result of which the rubber tube becomes worn soon.

Under these circumstances, various improvements have been heretofore proposed to prevent damages caused by such crushed pieces.

For example, in Japanese Utility Model Application Laid-Open No. 55-34075 which was filed by the same assignee as the present application, there is proposed a rubber tube for dredging work in which a plurality of metal rings having a tapered inner surface are embedded in an inner peripheral surface of the rubber tube in a suitably spaced relation.

This rubber tube is provided with a connecting fitting 1 at an axial end thereof as shown in Fig. 1, and metal rings 2 are embedded in the inner peripheral surface of the connecting fitting in an axially spaced relation. The metal ring 2 of the rubber tube 3 has an inner peripheral surface 4 tapered towards one direction in an axial direction, said inner peripheral surface 4 being protruded from the inner peripheral surface of the rubber tube 3. Solid particles such as crushed pieces of coral contained in the current of earth and sand impinge upon the tapered inner peripheral surface 4 of the metal ring 2 and knocked off in an axial direction, after which they are carried away by high pressure fluids and discharged into the succeeding iron pipe.This rubber tube 3 for dredging work can minimize a chance for the solid particles 5 to impinge upon directly on the inner peripheral surface of the rubber tube by the provision of the metal rings 2, thus considerably improving the cut and tear and wear of the inner peripheral surface of the rubber tube.

However, since extremely high internal pressure is applied to the rubber tube 3 during the use, the rubber itself is radially bulged and end surfaces 6 of both axial ends of the metal rings 2 embedded into the rubber tube 3 are often peeled off from the surface in contact with the rubber. It is assumed that occurrence of such peel-off and damage of the metal rings 2 mainly results from a short of adhesive force which occurs during the step of manufacturing the rubber tube 2. That is, the method of manufacturing the rubber tube will be briefly explained. First, a plurality of metal rings 2 are positioned on a mandrel in a required spaced relation. Next, after unvulcanized rubber sheets 7 and strengthening cloth layers 8 have been successively laminated, an outer peripheral surface thereof is firmly rolled by a tape-like cloth 9 having a relatively large width.A reference numeral 10 designates a metal wire for tightening inally, it is charged into a vulcanizing can for vulcanization under predetermined vapor pressure. As may be understood from such a manufacturing step, in the tightening of the tape-like cloth 9, a tightening force with respect to the outer peripheral surface of the metal ring 2 is different from a tightening force with respect to the rubber sheet layer 7 to produce an unbalance of the tightening force. Thus, the tightening force at a boundary line, that is, at both end surfaces 6 of the metal rings 2, and it is considered that the peel-off and damage as described above occur by a boundary tension resulting from pressures applied from inside and outside of the rubber tube 3 or bending deformation of the rubber tube 3 when used.

The same assignee as the present application has proposed in Japanese Utility Model Application Laid-Open No. 55-85163 a rubber tube for dredging work in which a metal ring is provided with a metal ring, which has a longer axial length than an axial length of the first-mentioned metal ring, fixedly mounted by weling or the like on an inner peripheral surface thereof. This rubber tube will be described with reference to Fig. 2 in accordance with the manufacturing step.

Here, the same elements as those of the aforementioned prior art embodiment bear the same reference numerals. A rubber tube 11 is made by mounting unvulcanized rubber sheets 7, strengthening cloth layers 8 and metal rings 12 of which inner peripheral surface is flat on a mandrel and thereafter vulcanizing and molding the same. The thus vulcanized and molded rubber tube 11 is removed from the mandrel, and then a tapered cylindrical member 13 having a longer axial length than the metal ring 12 is mounted on the metal ring 12. This mounting is achieved by securing an outer peripheral portion having a large diameter at one end of the cylindrical member 13 to an inner peripheral surface of the metal ring 12 by means of spot welding or the like.Accordingly, it re quires trouble in molding the rubber tube 11 for dredging work, and in addition, since the metal rings 12 are embedded into the rubber sheet 7, high temperature heat of weling is directly transmitted to the rubber elastic material in the neighbourhood, the rubber material in the neighbourhood is heat-deterio rated to possibly lower the adhesive strength ot the metal rings 12. Furthermore, possible occurrence of the peel-off and damage as described above still remains.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rubber tube for dredging work provided with metal rings which are rigidly mounted on an inner surface of the rubber tube and can effectively cope with tear-off, wear and damage given by crushed pieces of coral or the like.

It is a further object of the present invention to provide a rubber tube for dredging work in which a metal ring comprises a ring-like body portion and a guide ring member of substantially truncated cone which is fitted into said body portion and receives crushed pieces of coral and the like, said guide member being possible to be welded to the body portion without deterioration of the rubber tube by welding heat.

In accordance with the present invention, there is provided a rubber tube for dredging work comprising a tubular body made of rubber in which one or more strengthening clothes are embedded, and a plurality of metal rings arranged in an axially suitably spaced relation which are embedded in an inner per ipheral surface of said tubular body and of which inner peripheral surface forms a part of the inner peripheral surface of said tubular body, wherein each of said metal rings has an outer peripheral surface having a surface substantially parallel to an axis of said tubular body and an inner peripheral surface having a guide portion inclined in an axial direction of the tubular body from an inlet to an outlet in a moving direction of fluids to be dredged, and a radial thickness of both ends in an axial direction of each metal ring is thin.

In accordance with the present invention, there is further provided a rubber tube for dredging work wherein a metal ring comprises a body portion of substantially cylindrical shape embedded in an inner peripheral surface of a tubular body, and a cylindrical ring member of substantially truncated cone fitted into said body portion. The body portion and the ring member are connected by an engaging pin one end of which is protruded from an outer peripheral surface of the ring member and an annular groove formed in the body portion in such a manner that the other end of the engaging pin is fitted. The axial length of the ring member is greater than the length of the axial length of the body portion.

In the rubber tube for dredging work in accordance with the present invention, the outer peripheral surface of the metal ring is formed into a surface substantially parallel to the axial direction to increase the bonding force thereof with the rubber tubular body, and the radial length, that is, the thickness of both ends in a radial direction of the metal ring is made thin to minimize peel-off thereof from the tubular member occurred at said end surface portions.

In accordance with another preferred embodiment of the present invention, there is provided a ring member of substantially truncated cone whose diameter is gradually reduced from inlet to outlet direction of fluids to be dredged, in a manner similar to prior arts, said ring member being mounted on the body portion of the metal ring by means of an engaging pin, said engaging pin being deposited. This deposition is applied merely to a part of the engaging pin and welding heat is transmitted to the tubular body through the pin. Thus, heat is lowered through such a transmission medium and the rubber of the tubular body is not heat-detericrated.

BRIEF DESCRIPTION OF THE DRAWINGS Figure t is a plan view partly cut of a conventional rubber tube for dredging work.

Figure 2 is a sectional view partly cut of a further form of a conventional rubber tube for dredging work.

Figure 3 is a plan view partly cut showing one embodiment of a rubber tube for dredging work in accordance with the present invention.

Figure 4 is a sectional view in an enlarged scale showing a part of the rubber tube of Fig.

3.

Figure 5 is a sectional view showing a part of another embodiment of the present invention.

Figure 6 is a sectional view showing a part of a still another embodiment of the present invention.

Figure 7 is a plan view partly cut showing another embodiment of the present invention.

Figure 8 is a sectional view in an enlarged scale showing the rubber tube of Fig. 3.

Figures 9 through Figure 12 are respectively views showing another embodiments, and are sectional views in an enlarged scale only for essential portions thereof.

DESCRIPTION OF THE PREFERRED EMBODI MENTS Embodiments of a rubber tube for dredging work in accordance with present invention will now be described. Throughout the embodiments, like elements bear like reference numerals.

First, a first embodiment of the present invention shown in Figs. 3 and 4 will be described. The rubber tube for dredging work is generally indicated at 21. This rubber tube 21 is composed of an outer surface rubber layer 23 embedded into a plurality of strengthening cloth layers 22 and an inner surface rubber layer 24 formed integral with the innter peripheral surface of the rubber layer 23. Connecting metal pipes 25 are rigidly mounted by vulcanizing bonding to both ends in an axial direction of the rubber tube 21. Further, a plurality of metal rings 26 are embedded into the inner surface rubber layer 24 of the rubber tube 21 in such a manner that the respective inner peripheral surfaces are exposed to the inner peripheral surface of the inner surface rubber layer 24.

The metal ring 26 has an inner peripheral surface 27 of substantially convex-shaped section having a central surface 27a parallel to the axial direction and left and right tapered surfaces 27b, 27c formed to be tapered from both ends of said central surface 27a to portions in the vicinity of both ends in an axial direction of the metal ring 26. An outer peripheral surface 28 of the metal ring 26 has an annular rib 29 having a section of substantially trapezoid in the central portion in an axial direction and left and right surfaces 28a, 28b extending from both ends of the annular rib 29 to both ends in an axial direction of the metal ring 26, said left and right surfaces 28a, 28b being parallel in an axial direction.

In the first embodiment, the thickness t of left and right ends of the metal ring 26 is about 9 mm, and the height of a annular rib 29 is about 40 mm. Each of the metal rings 26 has its axial length, i.e., width W of 150 mm, and are embedded into the inner surface rubber layer 24 of the rubber tube 21 having the inside diameter of 700 mm at an interval i of 150 mm. In order that the rubber tube 21 may be incorporated into a delivery line of a pipe-line for dredging work, the outer peripheral portions of the connecting metal pipe and each metal ring 26 are rolled by a wire 30 through a part of the outer surface layer 23 and the strengthening cloth layer 22. It is of course that said wire 30 can be wound about one layer of the strengthening cloth layers 22.

Where the rubber tube 21 is used for a suction line, a fiber rope can be used in place of the wire 30.

In the first embodiment, the outer peripheral surface 28 of the metal ring 26 is formed into a surface parallel to the axial direction, and the annular rib 29 for increasing the bonding force with respect to the outer surface layer 23 is formed integral with the central portion of the outer peripheral surface 28. The metal ring 26, which has a thickness necessary for withstanding a wear resulting from impingement thereof upon crushed pieces of coral and crushed stones, is inevitably formed with vertical left and right ends corresponding to said thickness.However, a portion from said ends to the annular rib 29 is formed with relatively wide left and right surfaces 28a, 28b parallel to the axial direction, and said left and right surfaces 28a, 28b are firmly bonded by the outer surface rubber layer 23, the inner surface rubber layer 24 and the strengthening cloth layer 22, whereby even if a peel-off and damage should occur at said relatively thin vertical ends, furthe growth of such damage can be prevented. The inner peripheral surface 27 of the metal ring 26 is symmetrically tapered from the center with respect to the axial direction. Thus, even if the left and right ends of the rubber tube 21 are connected in either normal or reverse direction with respect to the flowing direction of fluid, the metal rings 26 may effectively cope with respect to the peel-off and damage caused by impingement of the crushed pieces of coral and the like.

In a second embodiment of a rubber tube for dredging work in accordance with the present invention, two annular ribs 32, 33 similar to the above-described annular rib 29 are provided on the outer peripheral surface 31 of the metal ring 26 in a suitably spaced relation. A wire is tightened between the annular ribs 32 and 33. The bonding between the metal rings 26 and the rubber tube is further strengthened by these annular ribs 32, 33. An outer peripheral surface of the outer surface rubber layer 23 between said pair of annular ribs 32, 33 is formed with a concave groove 34. When a bending force is exerted on the rubber tube 21 due to movement of a work boat or a tide, etc., said concave groove 34 absorbs a compressive force acting axially of the rubber tube 21 to prevent buckling deformation of the rubber tube 21 in a direction of the inside diameter.

In a third embodiment of the present invention shown in Fig. 6, an outer peripheral surface 35 of the metal ring 26 is formed with a convex curveed surface depicted by a gentle continuous curve. A wire 30 is evenly rolled on said outer peripheral surface 35 along said convex curved surface through the strengthening cloth layer 22 and a part of the outer surface rubber layer 23. The outer peripheral surface 35 forms the convex curved surface whereby the rolling force of the wire 30 is evenly applied and the thickness of both ends in an axial direction of the metal rings 26 can be minimized. Accordingly, the peeloff and damage at the ends hardly occur.

In a fourth embodiment of the present invention shown in Figs. 7 and 8, there is provided a metal ring 41 which is different from those of the above-described embodiments. This metal ring 41 is composed of a cylindrical body portion 42 whose thickness t is extremely smaller than the axial length thereof, that is, the width W, and a ring member 44 in the form of a truncated cone mounted on said body portion 42 through an engaging pin 43. The body portion 42 is integrally formed with an annular rib 45 outwardly protruded in the central portion of the outer peripheral surface thereof, and the an nular rib 45 is formed in its inner surface with an annular groove 46. The ring member 44 in the form of a truncated cone has its axial length, that is, the width W, which is greater than the width W of the body portion 42.

On the outer peripheral surface close to a large-diameter end of the ring member 44 in the form of a truncated cone are provided four engaging pins 43 which are protruded outwardly and provided with equal angle and radially, and these engaging pins 43 are fitted into the annular groove 46 of the body portion 42 whereby the ring member 44 is coaxially mounted on the body portion 42. A large-diameter end of the ring member 44 is positioned in registration with one axial end, the left end in Figs. 7 and 8, of the body portion 42, whereas a small-diameter end of the ring member 44 is positioned substantially in registration with the left end of the adjacent body portion 42 suitably spaced therefrom and arranged.

The truncated cone shaped ring member 44 is first inserted into the body portion 42 fixed by the rubber layers 23, 24 and strengthening cloth layer 22, after which the engaging pins 43 are inserted into holes bored before hand in the ring member 44, and the forward ends of the pins are extended into the annular groove 46. Next, the rear ends of the engag ing pins 43 are secrured to the ring member 44 by welding.

In this manner, the tapered or truncated cone shaped ring member 44 may be simply mounted on the inner peripheral surface of the pre-molded rubber tube. Moreover, since the high temperature heat generated when the engaging pins are welded is transmitted to the rubber tube only through four engaging pins 43 and the contact area between the engaging pins 43 and the body portion 42 is small, heat transmitted to the rubber tube during the welding work is very small in amount. Accordingly, the rubber elastic material around the body portion 42 is not heat-deteriorated.

Furthermore, since the body portion 42 embedded in the inner surface layer 24 has a surface parallel to the axis which is far lengthy as compared with the end 47 perpendicular to the axis X-X, the tightening force caused by the strengthening cloth layer 22 acts on said surface when the rubber tube is vulcanized to rigidly bond it to the rubber layer. Thus, even if the peel-off from the rubber layer at the end 47 should occur, it is possible to prevent further growth of such a damage. In this embodiment, the body portion 42 of the metal ring 41 has its width W of 100 mm, whereas the thickness t is approximately 15 mm. The spacing i between the body portions 42 is set to 300 mm.Accordingly, in order to prevent the crushed pieces of coral or the like from impinging upon the inner surface rubber layer 24 between the body portions 42, the ring member 44 must have its width formed greater than the width W of the body portion 42. In the present embodiment, the width W1 of the ring member 44 is set to 400 mm, and the entire inner peripheral surface of the inner surface rubber layer 24 between the body portions is covered with the ring member 44.

Since the ring member 44 is formed into a tapered configuration, the crushed pieces of coral and the like impinged upon the ring member 44 are knocked off in an axial direction and carried away by a current of high pressure mud. It is therefore of course that the ring member 44 need not to wholly cover the inner surface rubber layer 24 between the body portions 42 but can be of the width which terminates before the front end of the succeeding body portion 42.

In a fifth embodiment of the presesnt invention shown in Fig. 9, the width of the ring member 51 is the same as the width W1 of the ring member 41 in the aforementioned fourth embodiment but the mounting position of the engaging pins 43 is set somewhat closer to the small-diameter side than that of the aforementioned fourth embodiment, whereby the large-diameter end of the ring member 51 is positioned to be protruded from axial one end of the body portion 42, i.e., from the left end in Fig. 9.Thereby, the large-diameter end of the ring member 51 can cover the inner surface rubber layer 24 on the left side of the corresponding body portion 42, and the small-diameter end of the ring member 51 can cover the inner surface rubber layer 24 on the right side of the corresponding body portion 42, thus preventing the rubber layer 24 in these protions from being peeled off and damaged by the crushed pieces of coral or the like.

In a sixth embodiment of the present invention shown in Fig. 10, an annular groove 53 is provided in the inner peripheral surface of the metal ring 26 in the third embodiment shown in Fig. 6 and a ring member 54 in the form of a truncated cone similar to the ring members 44 and 51 as shown in Figs. 7 to 9. Since the central portion of the metal ring 26 has a large wall-thickness, the annular rib 45 as in the aforementioned fourth and fifth embodiments need not be provided, and a groove is merely cut in said large wall-thickness portion to form the annular groove 53.

In a seventh embodiment of the present invention shown in Fig. 11, a body portion of the metal ring 41 is composed of a pair of metal web-like rings 56 and 57. Plural sets of said web-like rings 56, 57 are embedded in a suitably spaced relation along the axis of the rubber tube 21. Between opposed ends of the pair of web-like rings 56 and 57 is formed a recessed gap 58 having the depth equal to the thickness t of these rings 56 and 57, and the distance Wa between the ends is slightly longer than the outside diameter of the engaging pin 43. The thickness t of the web-like rings 56 and 57 is far shorter than the width Wt, W2 which is the axial length thereof similarly to the aforementioned fourth embodiment.That is, in the seventh emdbodiment, the body portion 42 is not integrally formed with the annular groove 46, as in the aforementioned fourth embodiment, but the gap 58 is provided between the opposed ends of the pair of web-like rings 56 and 57 to use it as the annular groove.

An eighth embodiment of the present invention shown in Fig. 12 has a structure similar to that of the aforementioned seventh embodiment but is constructed such that the axial length, i.e., the width of the ring member 59 is made longer than the ring member 51, and the small-diameter portion of the succeeding ring member 59 is inserted into the largediameter end thereof and the small-diameter end inserted into the large-diameter end of the preceding ring member 59 so that they are placed one above the other. This can prevent impingement of the crushed pieces of coral or the like upon the inner surfae rubber layer 24.

Claims

1. A rubber tube for dredging work comprising a tubular body made of rubber having one or more strengthening cloth layers embedded therein, and a plurality of metal rings axially arranged in a suitably spaced relation which are embedded in an inner peripheral surface of said tubular body and which inner periphral surface forms a part of the inner peripheral surface of said tubular body, each of said metal rings having an outer peripheral surface having a surface substantially parallel to an axis of said tubular body and an inner peripheral surface having a guide portion which is inclined in the axial direction of said tubular body from an inlet in a moving direction of fluids to be dredged towards an outlet direction, a radial thickness of both ends in an axial direction of each of said metal rings being made thin.

2. A rubber tube for dredging work according to Claim 1, wherein said metal ring is formed in a central portion in an axial direction of said outer peripheral surface thereof with an outwardly protruded annular rib.

3. A rubber tube for dredging work according to Claim 1, wherein said outer peripheral surface of said metal ring is formed with an outwardly protruded first annular rib axially spaced from one end thereof and an outwardly protruded second annular rib axially spaced from said first annular rib and axially spaced from the other end of said outer peripheral surface.

4. A rubber tube for dredging work according to Claim 1, wherein said outer peripheral surface of said metal ring is in the form of a convex curved surface of which axial both ends are thin in wall-thickness and a portion towards a central portion increases in wallthickness.

5. A rubber tube for dredging work according to Claim 1, wherein said guide portion of said inner peripheral surface has a section substantially in the form of a truncated cone, which section is axially protruded in a central portion in the direction of the axis thereof.

6. A rubber tube for dredging work according to Claim 1, wherein said metal ring comprises a substantially cylindrical body portion having said outer peripheral surface and a substantially truncated cone shaped ring member fitted into said body portion and formed in its inner peripheral surface with said guide portion, said body portion and said ring member being connected by means of a plurality of engaging pins of which one end is mounted on said ring member and the other end is fitted in an annular groove formed in said body portion.

7. A rubber tube for dredging work according to Claim 6, wherein the axial length of said ring member is greater than that of said body portion.

8. A rubber tube for dredging work according to Claim 6, wherein an end on the small-diameter side of said ring member extends up to the neighbourhood of an end on the large-diameter side of said ring member of said metal ring adjacent thereto.

9. A rubber tube for dreding work according to Claim 6, wherein the end on the smalldiameter side of said ring member is fitted into the end on the large-diameter side of said ring member of said metal ring adjacent thereto.

10. A rubber tube for dredging work according to Claim 6, wherein said annular groove is provided in the inner surface of the annular rib outwardly protruded from the central portion in the outer periphery of said body portion.

11. A rubber tube for dredging work according to Claim 6, wherein said body portion is constructed such that a pair of web-like ring members are axially arranged in parallel, and opposed axial ends of each of said web-like ring members are positioned in spaced relation, said space serving as said annular groove.

12. A rubber tube for dredging work, substantially as hereinbefore described with reference to Figs. 3, 4 and 8 of the accompanying drawings.

13. A rubber tube for dredging work, substantially as hereinbefore described with refer ence to any one of Figs. 5, 6, 7, 9, 10, 11 and 12 of the accompanying drawings.