WO2014128042A1

WO2014128042A1 - A splicing method for splicing the ends of a conveyor belt

Info

Publication number: WO2014128042A1
Application number: PCT/EP2014/052735
Authority: WO
Inventors: Tao Huang; Yuping Wang
Original assignee: Nv Bekaert Sa
Priority date: 2013-02-21
Filing date: 2014-02-12
Publication date: 2014-08-28

Abstract

The invention provides a splicing method for conveyor belt. The splicing method takes short splicing time and low cost. The invention also provides a spliced conveyor belt with good strength, good flexibility and low cost.

Description

A splicing method for splicing the ends of a conveyor belt

Description

Technical Field

[1 ] The invention relates to a method for splicing conveyor belt ends to one another. It also relates to a conveyor belt comprising such splice.

Background Art

[2] Belts for conveying bulk goods are made predominantly with two kinds of reinforcement: there is the textile reinforced kind of conveyor belts wherein the belt is reinforced with a fabric of natural or man-made fibres and there are steel cord reinforced belts wherein the belt carcass is composed of parallel steel cords not connected to one another and extending the length of the belt.

[3] A unique kind of belt reinforcement is Fleximat® ('Fleximat' is a registered trademark of NV Bekaert SA). It is a fabric composed of steel cords comprising parallel steel cords arranged in warp direction crossed by parallel steel cords in weft direction, the warp steel cords and the weft steel cords are held together with a yarn. A belt reinforced with Fleximat® possesses excellent properties in use like a high impact resistance, a high heat resistance, and a high tear resistance. Therefore it is many times chosen as the reinforcement of heavy duty intermediate strength belts

(lateral strengths of 350 N/mm to 1600 N/mm and in special cases to 2000

N/mm). Typical uses are in stone quarries, coke plants, cement plants, sintering plants and power plant.

[4] Any conveyor belt may break when suffering too heavy loads in operation.

As downtime in the type of installations wherein Fleximat® is used leads to immediate losses, the repair of the broken belt in a short time and with a strength close to the strength of the original belt is important. [5] The finger splicing method is one widely used method for splicing textile fabric and also Fleximat® reinforced conveyor belts. In a finger splice the one end of the conveyor belt is cut into extending 'fingers' after removing belt material. The other end of the belt is cut likewise in a precisely matching pattern. Thereafter the inter-digitated fingers are vulcanised to one another. The finger splicing method yields a splice with good strength (the strength approaches the strength of the conveyor belt with increasing splice length) and very good flexibility (the flexibility is equal to that of the conveyor belt for all practical purposes). It offers to best performance in terms of endurance and is used for the first mounting of the belt or the mending of the ruptured conveyor belt. However, this method is

expensive and time consuming. Longer splicing time means more output loss when a belt fracture has occurred.

[6] The mechanical fastener splicing method is another widely used splicing method. In this case both ends of the belt are provided with mechanical fasteners that are clinched - possibly with the help of staples - to both belt ends in an alternating matching way. The fasteners form eyelets through which a connector rod is slid thereby forming a hinge connection. This method is cheap and takes a short time, but the splicing quality is not good, as the strength of the splice is poor. As the complete load on the belt must be transferred over the clamps attached to the belt ends, there is a risk that the clamps, even when held with staples, tear out of the belt end. The splice strength can be improved by taking longer fasteners, but then the flexibility of the splice is jeopardised as the fasteners are metal parts that do not bend and curb up the belt end when guided over the end drums of the conveyor belt installation.

[7] US 5,620,085 discloses an improved mechanical fastener splicing method.

In this mechanical fastener splicing method, the fasteners are clinched to the belt ends, and then are vulcanized to the belt ends. As the fasteners and staples are metallic and hard, they will mar the surface of the

vulcanisation plates used for vulcanising the rubber as the vulcanisation plates must be tightened over the splicing region. This is highly disliked as those vulcanisation plates are expensive.

[8] There is therefore a constant need to find a splicing method which has a good balance on splicing quality (strength of the splice and flexibility of the splice), cost and splicing time.

Disclosure of Invention

[9] One object of the present invention is to overcome the problems of the prior art.

[10] Another object of the present invention is to provide a method of splicing conveyor belt.

[1 1 ] A third object of the present invention is to provide a spliced conveyor belt with good strength on the splice, good flexibility on the splice at a low cost and within an acceptable timeframe.

[12] According to the one aspect of the invention, a method for splicing a

conveyor belt is provided. The method is for splicing two ends of a conveyor belt which has at least one reinforcing layer and elastomer layers covering the at least one reinforcing layer. The method comprises the following steps:

1 ) set a splicing area at each end of conveyor belt, the splicing area

extends over the width of conveyor belt;

2) remove a first sheet from the upside of conveyor belt in the splicing area;

3) put at least one reinforcing ply at the splicing areas where the first sheets have been removed;

4) and then do vulcanization;

5) join the splicing areas by one or more mechanical fastener. [13] With 'reinforcing layer' is meant a layer of reinforcing material that extends over the complete length of the belt. The reinforcing material can be a fabric made of natural (e.g. cotton) or man-made fibres (polyester, rayonne, steel cord). Most preferred is if the fabric is made of Fleximat®. Alternatively the reinforcing material can be steel cords that are arranged parallel to one another but that remain individual and are not connected to one another.

[14] The 'reinforcing layer' is covered at both sides with an 'elastomer layer'.

Different elastomer layers of different composition can be present in a belt. For example the elastomer layers in contact with the reinforcing layer may contain additives to improve adhesion. Conversely the outer elastomer layer - on which the bulk goods will impact - maybe made of a tougher, wear resistant type of rubber.

[15] With 'splice' is meant that area of the closed belt wherein the joint between belt ends is made. 'Splicing area' means a place at the end of a conveyor belt that is provided for making the splice. The splicing area is delimited by the transition to the undisturbed belt structure.

[16] With a 'sheet' is meant a part of conveyor belt that has a certain thickness, width and length. The sheet extends over the width of the splicing area. The sheet may have the shape of a parallelogram or rectangle.

[17] A 'reinforcing ply' is a sheet of unvulcanized elastomer that comprises

reinforcing material in the form of a fabric made of natural or man-made fibers or in the form of parallel arranged natural or man-made cords encased in elastomer. It is used for strengthening the splice of the conveyor belt at the splicing area.

The purpose is to place the reinforcing plies in the splicing areas so that the direction of the reinforcing material in is weft direction of the conveyor belt.

In case the conveyor belt has a reinforcing layer with both warp and weft reinforcements, the density or population of reinforcing material in the reinforcing ply is preferably greater than the density of weft reinforcement in the conveyor belt.

[18] A conveyor belt has two sides extending over its width. A 'upside' and a 'downside' are used for distinguishing between these two sides. The 'upside' is for one side of the conveyor belt, in contrast, the 'downside' is for another side opposite to the upside. To the present invention, 'upside' or 'downside' wouldn't be a limitation of the direction.

[19] In the inventive method vulcanization is performed prior to mechanical fastening, which means the vulcanization process is before the

mechanical fastening process. By doing so, the invention splicing method brings advantages of low cost, short splicing time, high strength on the splice and high flexibility on the splice.

[20] Compared with the conventional finger splicing method, the invention method provides a lower cost and shorter splicing time while making the splicing strength acceptable. Indeed, most of the time for making a finger splices goes into the preparation of the belt ends in order to make them ready for splicing. This time of preparing the belt ends is virtually eliminated in the inventive method.

[21 ] Compared with the conventional mechanical fastener splicing method, the inventive method provides an equal flexibility on the splice while improving the splicing strength for the same fastener clamping length.

[22] Compared to the splicing method of US 5,620,085, the present invention changes the sequence of the mechanical fastening process and the vulcanization process. To the method of US 5,620,085, as the fasteners and staples are metallic and hard, they will mar the surface of the vulcanisation plates used for vulcanising the rubber as the vulcanisation plates must be tightened over the splicing region. This is highly disliked as those vulcanisation plates are expensive. The invention method avoids these drawbacks and saves the cost. [23] Preferably, in step 2) of the present invention method, further remove a second sheet from the downside of the conveyor belt in the splicing area, and in step 3), put at least one unvulcanized elastomer sheet or at least one reinforcing ply at the splicing areas where the second sheets have been removed. As the elastomer layers of conveyor belt in the splicing area would suffer one more vulcanization process if they are not removed, and this will weaken the strength of the splice, the downside of the conveyor belt in the splicing area is preferably removed. Instead, at least one unvulcanized elastomer sheet or at least one reinforcing ply is covered on this area.

[24] In a preferably embodiment, the at least one reinforcing layer in the

conveyor belt comprises a steel fabric comprising warp steel cords and weft steel cords, the warp steel cords and the weft steel cords are held together with a yarn, for example, Fleximat®. Preferably the first sheet removed in step 2) includes the weft steel cords, and it means the weft steel cords are also removed while the warp steel cords remain intact.

[25] According to the present invention, optionally, the method comprises a further step between step 3) and step 4), the further step is: cover the reinforcing ply with at least one unvulcanized elastomer sheet. The elastomer sheet is for adjusting the overall thickness in the splice area in case the splicing area covered with reinforcing ply doesn't have the same overall thickness as the remainder of the conveyor belt.

[26] According to the present invention, preferably, in step 1 ) the splicing area at each end of the conveyor belt is set to a length L starting from the belt end and taken along the longitudinal direction of the conveyor belt, and L is not more than 300mm. More preferably, L is in a range of 15 to 200 mm. The shorter the length L, the higher the flexibility of the splice. The longer the length L, the bigger the strength of the splice.

[27] In the conventional mechanical splicing method, in order to obtain

sufficient strength in the splice, the total splicing area has a very long length, even more than 1250 mm. As a result, the spliced conveyor belt has a poor performance in flexibility at the splice. The inventor is surprised to find that the length of the splicing area in the present inventive method is reduced considerably. According to the above preferable invention method, the splicing area only needs a very short length, while the flexibility of the splice and the strength of the splice are still good. This greatly improves the lifetime of the splice compared to conventional mechanical splices without an excessive increase in splicing time and cost compared to when for example a finger splice is used.

[28] To the step 1 ), the setting of the splicing area also includes the process of cutting the end of conveyor belt to have a desired end shape. Preferably, the ends of conveyor belt are cut along a simple curve such as a straight line or a circle bow or triangular. The ends of the conveyor belt are preferably cut along one or more straight sections which have an angle between 0° and 35° perpendicular to the longitudinal direction of the conveyor belt. The end-shape should not be too complicated as this will add the preparation time of the splice. So a straight cut is most preferred. The straight cut can be made perpendicular to the travelling direction (the longitudinal direction) of the belt (0°bias angle) but an oblique cutting direction up to a bias angle of 35° is also possible. An oblique cutting direction has the advantage that the changeover from belt to splice is not abrupt. An abrupt changeover leads to pounding over the drive drums during use.

[29] According to one preferable embodiment of the present invention, the

reinforcing ply has a strength being not less than 50% of the strength of conveyor belt outside the splicing areas. Thus the strength of the splice is close to the strength of conveyor belt outside the splice.

[30] The number of the reinforcing plies is at least one. More reinforcing plies lead to a higher splice strength. Preferably the number of reinforcing plies is one more than the number of reinforcing layers and the reinforcing plies are placed alternating with the reinforcing layer. For example in the case of a single reinforcing layer one reinforcing ply is present on top of the reinforcing layer and one is present below the reinforcing layer. So the number of the reinforcing ply is determined by the requirement of the final spliced conveyor belt.

[31 ] According to the present invention, the reinforcing ply is preferable to be a ply comprises at least one metal element encased in an unvulcanized elastomer.

[32] The metal element may be steel cord, steel wire or steel fabric. Preferably, the metal element is High Elongation steel cord for high impact resistance.

[33] Preferably, in case the ends of conveyor belt is cut straight, after putting the reinforcing ply on the splicing areas in step 3), the metal element in said reinforcing ply is aligned parallel to the conveyor belt end. Especially for the conveyor belt in which the reinforcing layer comprising a plurality of steel cords or steel wires aligned along the longitudinal direction of conveyor belt, the preferable setting or arrangement of the metal element and the reinforcing ply provides a synthesis of the strengths from different directions.

[34] The mechanical fastener can be anyone of the existing mechanical

fasteners in the art. Preferably, the mechanical fastener is a clamp held by means of a screw, staple, rivet or bolt. The size of the mechanical fastener can be adjusted according to the requirement of the strength of the splice of conveyor belt. The bigger the size of the mechanical fastener, the bigger the strength of the splice of conveyor belt.

[35] According to the present invention, preferably, the unvulcanized elastomer in the reinforcing ply is unvulcanized rubber.

[36] According to another aspect of the invention, a spliced conveyor belt with high strength at the splice, high flexibility at the splice and low cost is provided. The conveyor belt comprises at least one reinforcing layer, elastomer layers covering said at least one reinforcing layer and two ends. The two ends are spliced by the following method:

1 ) set a splicing area at each end of conveyor belt, the splicing area extends over the width of conveyor belt;

2) remove a first sheet from the upside of conveyor belt in the splicing area;

3) put at least one reinforcing ply at the splicing area where the first sheets have been removed;

4) and then do vulcanization;

5) join the splicing areas by one or more mechanical fastener.

[37] Optionally, the method comprises a further step between step 3) and step 4), the further step is: cover said reinforcing ply with at least one

unvulcanized elastomer sheet.

[38] The spliced conveyor belt has high strength and flexibility, and it has low cost and long lifetime.

Brief Description of Figures in the Drawings

[39] Figure 1 a to 1 e show the different steps in the making of the splice to

connect two belt ends.

[40] Figure 2a and 2b show different possible cutting shapes at the end of the conveyor belt. .

[41 ] Figure 3 shows a front view of conveyor belt spliced by the another type of mechanical splicing.

Mode(s) for Carrying Out the Invention

[42] The present invention provides a new method for splicing conveyor belt, especially for a ruptured conveyor belt. The conveyor belt is anyone of the conveyor belt known in the art, for example, a Fleximat® impact metal weft (IW) conveyor belt such as described in EP0096929. Figure 1 a shows the cross section of a typical IW reinforced conveyor belt 102. Normally, the conveyor belt 102 has at least one reinforcing layer (warp steel cords 104, weft steel cords 108) and elastomer layers 106, 107. The reinforcing layer is a layer comprising longitudinally extending steel cords 104 and transverse reinforcement steel cords 108 that are held together with a binding yarn (not shown).The elastomer layers 106, 107 are rubber layers vulcanised to the steel fabric 104,108.

Figures 1 a to 1 e show the different steps in splicing the two ends 1 10, 1 10' of a conveyor belt 102 according a preferred method of the invention. The first preferred splicing method is:

1 ) set a splicing area at each end of conveyor belt 1 10, 1 10'. The splicing area is a rectangle with a length L, L' being 50 mm and a width extending over the width of the belt;

2) Figure 1 b: a first sheet 1 12, 1 12' is removed from the upside of conveyor belt 102 in the splicing area by pealing and cutting it off as close as possible to the warp steel cords 104 (the weft steel cords 108 in the splicing area is also removed); a second sheet 1 13, 1 13' is removed from the downside of conveyor belt 102 in the splicing area by pealing and cutting it off as close as possible to the warp steel cords104;

3) Figure 1 c: one reinforcing ply 1 14, 1 14' is put at each splicing area where the first sheet 1 12, 1 12' has been removed, the reinforcing ply 1 14, 1 14' has a strength being 80% of the strength of the conveyor belt 102 outside the splicing areas; one un-vulcanized elastomer ply 1 15, 1 15' is put at each splicing area where the second sheet 1 13, 1 13' has been removed;

4) and then do vulcanization: Figure 1 d. To this end one or two elements of a mobile vulcanisation press 120, 120' are clamped to the end of the belt to provide pressure and heat to the splicing area. So the length to be vulcanised is considerably shorter than the length required in a finger splice which reduces the set up time for vulcanisation. During

vulcanisation the reinforcing ply forms a strong bond with the conveyor belt end.

5) Figure 1 e: join the splicing areas by clamps 130, 130' that are

alternatingly mounted at the belt ends. The clamps 130, 130' are secured by pressing them on the belt end and by means of bolts 132, 132' extending through the clamps, the reinforcing layer 104, the reinforcing ply 1 14, 1 14' and the elastomer ply 1 15, 1 15'. Care should be taken not to overly damage the steel cords during bolting. Possible suppliers of clamps are GORO (Celles, France), Flexco® (Downers Grove, Illinois, US) or Mato (Offenbach, Germany).

The alternating clamps form eyelets through which a connector rod 134 is inserted to form a hinged connection.

[44] The reinforcing ply 1 14, 1 14' is a flat belt comprising high elongation steel cords 1 16 with a structure of 3x7 encased in rubber 1 17. The reinforcing ply 1 14, 1 14' is put on the splicing area to make the steel cords 1 16 being aligned parallel to the straight cut of the conveyor belt end.

[45] A static strength test showed that the splice 100 of conveyor belt 102 has a strength being 98.5% of the strength of of the conveyor belt 102 outside the splice. Also the spliced conveyor belt 102 has higher flexibility and longer lifetime than the conveyor belt spliced by the conventional mechanical fastener splicing method.

[46] Optionally an unvulcanized elastomer sheet 1 18, 1 18' can be put on top of the reinforcement ply in order to equalise the surface of the belt end with the remainder of the belt (Figure 1 c, second preferred embodiment). After vulcanisation, this elastomer sheet forms one with the reinforcement ply and the conveyor belt end.

[47] The test shows that the splice of conveyor belt spliced by second

preferred method has a static strength being 82.3% of the strength of the conveyor belt outside the splice. Also the spliced conveyor belt has higher flexibility and longer lifetime than the conveyor belt spliced by the conventional mechanical fastener splicing method.

[48] Figure 2a shows a conveyor belt spliced by the third preferred method of the invention. In third preferred splicing method : a splicing area is set at each end of conveyor belt 202, each end of conveyor belt 202 is cut straight at an angle a of 15° perpendicular to the longitudinal direction of conveyor belt 202. So the surface of splicing area is a trapezoid with sides parallel to the belt and the straingt cut. The length parallel to the belt is the length L, L' being 180 mm. The further steps of the method are equal to that of the first and the second embodiment except that a reinforcing ply is provided at either side of the reinforcing layer. As the splice is now under an angle of 165° with respect to the movement of the belt 240, the splice will run smoother over the drums of the belt installation and pounding of the splice is diminished.

[49] The test shows that the splice 200 of conveyor belt 202 has a static

strength being 95.3% of the strength of conveyor belt 202 outside the splice.

[50] In a fourth preferred embodiment of the method (Figure 2b), cutting is

done in the form of a V which means the cutting is along two straight sections, wherein both sides of the V make an angle a with the direction perpendicular to the belt which means both two straight sections have an angle a with the direction perpendicular to the belt. In this way the length of the splice can be reduced while pounding of the belt over the drum is diminished.

[51 ] In a fifth preferred embodiment depicted in Figure 3 the step of making a mechanical splice by means of an eyelet and rods is replaced by another mechanical splice system. In each end of the belt 310, 310' the reinforcing layer is at either side reinforced with a reinforcing ply 314, 315 and 314', 315' that is vulcanised to the belt end. This doubles the reinforcement capability of the belt. The alternative splice system 320 is in the form of an 'Η' profile made in textile reinforced vulcanised rubber. Both ends of the 'Η' shape slide over the belt end and are fastened by means of a series of screws 322, 322'. Such 'Super Screw lacing' mechanical fastener can be obtained from 'MLT Inc.', Princeton, US.

Compared with the conventional finger splicing method which takes long splicing time and cost, the invention method reduces the splicing time, even reduces 50% of the splicing time, the invention method also contributes to the reduction of the cost. Compared with the conventional mechanical fastener splicing method, the flexibility of the spliced conveyor belt is improved, especially the flexibility of the splice of conveyor belt is improved. Thus, the spliced conveyor belt with high flexibility is not easy to break, and the lifetime of the spliced conveyor belt is improved.

Claims

1 . A method of splicing two ends of a conveyor belt, said conveyor belt having at least one reinforcing layer and elastomer layers covering said at least one reinforcing layer, said method comprising the following steps:

1 ) setting a splicing area at each of said two ends of said conveyor belt, said splicing areas extending over the width of said conveyor belt;

2) removing first sheets from the upside of said conveyor belt in said splicing areas;

3) putting at least one reinforcing ply at each of said splicing areas where said first sheets have been removed;

4) vulcanizing said at least one reinforcing plies;

5) joining said splicing areas by one or more mechanical fastener.

2. A method as claimed in claim 1 , characterized in that, further in step 2), second sheets are removed from the downside of said conveyor belt in said splicing areas, and in step 3), at least one unvulcanized elastomer sheet or said at least one reinforcing ply is put at said splicing areas where said second sheets have been removed.

3. A method as claimed in claim 1 or 2, characterized in that said at least one reinforcing layer comprise a steel fabric comprising warp steel cords and weft steel cords, said warp steel cords and said weft steel cords are held together with a yarn.

4. A method as claimed in claim 3, characterized in that said first sheet removed in step 2) includes said weft steel cords.

5. A method as claimed in claim 1 or 4, characterized in that said method

comprises a further step between said step 3) and said step 4), said further step is: cover said reinforcing ply with at least one unvulcanized elastomer sheet.

6. A method as claimed in claim 1 or 5, characterized in that, when setting said splicing area in said step 1 ), said ends of said conveyor belt are cut along one or more straight sections, said straight sections having an angle between 0° and 35° perpendicular to the longitudinal direction of said conveyor belt.

7. A method as claimed in any one of claims 1 to 6, characterized in that, in step 1 ), each of said splicing area is set with a length L starting from the belt edge along the longitudinal direction of said conveyor belt, and said L is not more than 300mm.

8. A method as claimed in claim 7, characterized in that said L is in a range of 15 to 200 mm.

9. A method as claimed in any one of preceding claims, characterized in that said reinforcing ply has a strength being not less than 50% of the strength of said conveyor belt outside the splicing areas.

10. A method as claimed in claim 9, characterized in that said reinforcing ply

comprises at least one metal element encased in an unvulcanized elastomer.

1 1 .A method as claimed in claim 10, characterized in that said metal element is steel cord, steel wire or steel fabric.

12. A method as claimed in claim 10, characterized in that said steel cord is High Elongation cord.

13. A method as claimed in any one of claims 10 to 12, characterized in that, in

step 3), said metal element in said reinforcing ply is aligned parallel to said conveyor belt end.

14. A method as claimed in any one of preceding claims, characterized in that said mechanical fasteners are clamps held by means of a screw, staple, rivet or bolt.

15. A conveyor belt comprising a splice made according to the method as claimed in any one of claims 1 to 14.