Splicing of steel cord conveyor belts

Elastomers Compounding Processing

Standards /norms Equations Steel cords Inches / mm US dimensions Papers

Handling/Storage Reel dimensions Stringing Textile belt splices Textile belt splicing Steel cord belt splices Steel cord belt splicing Splice testing

First belt Strongest belt Strongest underground belt Highest capacity belt Longest belt Heaviest belt First self-extinguishing belt

Belt designation Carcass types Cover grades Elastomers Glossary of terms

Rip detection Splice length monitoring Opto-electronic monitoring Conveyor safety devices

Closed conveyor belts Energy saving belts Aramid belts

INSTALLATION

STEEL CORD CONVEYOR BELT SPLICING - STEP BY STEP
1		The components of a steel cord conveyor belt splice: 1) Cover sheets. 2) Transverse reinforcement embedded in unvulcanized core rubber. It is applied like a second core rubber sheet. 3) Core rubber sheets. 4) Steel cords with original core rubber. 5) Intermediate rubber strips.
2		Setup of the working table. For positioning of the bottom platen(s) of the curing press both belt ends are folded back. The bottom part of the vulcanizer is used as a working table.
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3		The belt ends have to be tensioned as much as possible to avoid sag. Both lengths will be laid one on top of the other over the whole splice length. If it is necessary to shorten the belt(s), a wedge-shaped strip of approx. 2 cm width is cut out of the upper cover so that the steel cords become visible. The steel cords will be cut with a high-speed abrasive cutting tool with fabric reinforced disc. Do not forget to take safety precautions!
4		The belt centre is marked on both belt ends and also at a minimum of three other points that are approx. 1,5 metres (5 feet) apart. These centre points are then joined into a centreline using a chalked string. Approximately half a metre behind the splice area a crossline is drawn at right angles to the centreline as a reference line. One marked belt end is placed on top of the other marked belt end. The centrelines on each end must be precisely aligned.
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5		The cover is cut transversally down to the cables. The knife is held at a 45° angle. The rubber edges will be removed as far as the first steel cord.The belt centre is marked on both belt ends and also at a minimum of three other points that are approx. 1,5 metres (5 feet) apart. These centre points are then joined into a centreline using a chalked string. Approx. half a metre behind the splice area a crossline is drawn at right angles to the centreline as a reference line. One marked belt end is placed on top of the other marked belt end. The centrelines on each end must be precisely aligned.
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6		By means of a tensioning tool the cover is removed, supported by a knife that cuts between the cover over the steel cords. Do not tear the cover off! The procedure is repeated for the bottom sides of the belt ends.
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7		The rubber between the steel cords is removed. The cords should be carefully buffed with a rotary brush. They remain completely covered by rubber after this procedure. This procedure can be done very conveniently with a "CordStripper" (see video on the left). "Piano wires" or similar methods should preferably not be used.
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8		The top and bottom sides of the separated steel cords will be brushed with a grooved wire brush. Do not "polish" the steel cords! The belt ends are roughened with a wire brush. Buffing dust will be swept off by means of a hand brush. Do not use any cleaning solvent! The steel cords will be coated with a special rubber solution and dry completely.
9		An unvulcanized cover rubber sheet is placed at the bottom of the splice on top of a separation cloth (Vulkatrix - see video). The cloth should be approx. 300 mm (12 inches) longer in the longitudinal directions. See also storage requirements for splicing material.
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10		The alignment is checked again.
10		The alignment is checked again.
11		The steel cords have to be positioned as determined by the belt manufacturer or by the standard (f.i. DIN 22129).
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12		By the way: No cable has contact to any other cable.
13		All gaps between the cables are carefully filled with intermediate core rubber up to the height of the cables. The entire splice area will be sparingly coated with rubber solution and dry completely. Rubber edges are applied on both beld sides, coated with solution and dry well. The edges are tapped thoroughly with a mallet. Protruding rubber is cut off. The straightness of the splice is again checked. Note: There are preformed splice mats on the market for simple configurations. They have been criticized because deformations can hardly be avoided, and at least the sides of the mats are exposed to contamination. Blisters and inclusions occur frequently. Irregularities cannot be compensated as is the case for a skilled splicer using noodle rubber when laying the cords.
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14		Traverses
		Heating platen
		Metal sheet
		Separation cloth (f.i. Vulcatrix)
		Steel cord conveyor belt
		Separation cloth (f.i. Vulcatrix)
		Metal sheet
		Heating platen
		Traverses
15		Edge bars, approx. 1 mm thinner than the belt, are placed against both belt edges (see video left side) and clamped outside the splice area. The bars are 1-2 mm (1/16 inch) thinner than the belt.
		Upper platens are placed an aligned (see video bottomright side). End locking bolts are tightened slightly. Oil pumps will be connected to upper traverses. End bolts are tightened thoroughly. Electrical cables are connected to the heating platens. A pressure of approx. 10 bar (150 psi) is applied with oil pumps.

16	The vulcanization is initiated by plugging the heating platens in. Pressure will be increased as temperature rises. Temperatures at all heating platens are controlled. Temperature is regulated by self-controlled heating platens or by switching energy on and off. After several minutes allow temperature to rise to 142°C (290°F). The curing time counts when temperature reaches 142°C (290°F). Disconnetion at 145°C (295°F). Plugging-in again when temperature drops to 142°C. After curing time has elapsed, platens will be allowed to cool down to 80°C (150°F). A typical heating/pressure curve is shown here. Important: Please use the appropriate figures of your belt supplier! Here only examples are given.
		A vulcanizer setup in a climatized working shed. The curing time is depending on belt thickness and rubber grade. As a rule of thumb, a curing time of 3 minutes per 1 mm belt thickness is required. Some further instructions are given at the last column of multiply textile conveyor belts.
17	Dismantling of Press: Traverses and end bolts will be loosened and removed. Upper heating platens will be removed. Edge clamps will be loosened and removed. Spliced belt will be lifted and lower heating platens are removed. Working platform will be removed. Rubber overflow at both edges will be trimmed off. Belt surface, ramps and edges are being inspected visually. Belt is put into service.

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And don't forget to have a break -

at the right time at the right place...!

STEEL CORD CONVEYOR BELT SPLICING - STEP BY STEP