VULCANIZED SPLICINGFOR STEEL CORD

CONVEYOR BELTSONE-STEP METHODTWO-STEP METHOD

1

VULCANIZING SPLICINGFOR STEEL CORD CONVEYOR BELTS

CONTENTS

INTRODUCTION

2

STANDARD PATTERN

2

SPLICING MATERIALS

4

SPLICING PROCEDURE

A. Preparation 5

B. Forming 6

C. Vulcanizing 13

D. Finishing 15

E. Precautions 15

2

INTRODUCTION

A vulcanized splice has many advantages over mechanical splices such as freedom from:

1. Tear hazard

2. Tight joint to hold material

3. Greater strength in the joint

This manual giving step by step of vulcanized splice for steel cord belt. Following is the cross

section for the steel cord conveyor belt with conventional construction.

Figure 1: Cross section of steel cord belt

STANDARD PATTERN OF ONE-STEP METHOD & TWO-STEP METHOD

Detailed drawings of specific belt specifications are available upon request.

(1) ONE-STEP METHOD

25S+15d+75

S+75

25

4d+15

502525

S15d+50

L: S+15d+150

Bel

t Wid

th

Unit: mmBelt Travel

CL22.5o

or 17o

3

(2) TWO-STEP METHOD

Step Length (S) Except heat resistant rubber

Steel cord d S Steel cord d S

construction Steel cord dia. Step length construction Steel cord dia. Step length

(mm) (mm) (mm) (mm)

3+9+15 2.3-2.5 300 7 x 7 2.5 250

2.6-3.0 350 2.6-3.1 300

3.1-3.4 400 3.2-3.4 350

3.5-3.6 450 3.5-3.8 400

3.7-3.9 500 3.9-4.1 450

4.0-4.3 550 4.2-4.6 500

4.4-4.7 600 4.7-5.2 550

4.8-4.9 650

5.0 700

Belt

CL

25 25SS

15d+50

15d+5L:2S+34d+165

Belt

Wid

th

Unit: mm4d+15

22.5o

or 17o

2S+19d+65

2S+19d+65

25

25

Tie Gum (W25)Cement (W90)

Steel CordCover Gum (W10)

Cover Gum (W10)

4

Steel cord d S Steel cord d S

construction Steel cord dia. Step length construction Steel cord dia. Step length

(mm) (mm) (mm) (mm)

7 x 19 (Sew) 5.0-5.2 650 7 x 19 (Open) 5.5 650

5.3-5.7 700 5.9 700

5.8 750 6.2 750

5.9-6.3 800 6.6 800

6.4-6.6 850 7.5 950

6.7-6.9 900 8.0 1000

7.0-7.2 950 8.5 1100

7.3-7.7 1000 9.0 1150

7.8 1050 9.6 1200

7.9-8.3 1100 10.3 1300

8.4-8.8 1150 10.8 1400

8.9-9.2 1200 11.5 1500

9.3-9.6 1250 12.5 1650

9.7-10.0 1300

10.1-10.6 1400

10.7 *

Note: *Please consults Bridgestone.

SPLICING MATERIALS

Cover Rubber

Heat Resistant Rubber Abrasion Impact & Cut Flame OilMaterialsGeneral F110 SF150 SF180 A2000 AS-A FX-S JIS, DIN,

MSHAOil AceH, L, G

Cover Gum W10 H12 T: H15B: 12

Q11 A10 Y10 X10 F10 L13

CoatingGum

W25 H20 T: H25B: N/A

Q23 Q23 W25 W25 W25 W25

NylonCloth

E41 N/A N/A N/A N/A E41 E41 E41 E41

RubberCement

W90 H90 T: H95B: H90

Q93 Q93 W90 W90 W90 W90

Shelf Life 6 mths 4 months 6 months

Note: (1) The above shelf life is subject to the materials stored at the condition below:

• Away from sunshine and heat

• In a dark and cool place with the temperature of less than 30oC, preferably

in a refrigerator.　When the materials are taken out from refrigerator, remove

moisture on the surface completely.

(2) The shelf life period is shown on a label attached to the splicing materials.

(3) Please consult the details of the material code and the dimensions of the

material with Bridgestone.

SPLICING PROCEDURE

A. PREPARATION

(1) Set a worktable on the frame of the conveyor.

Note: 1.

2. A

w

3. D

Work Table

∗ If a vulcathe angle

Lower Heat Plate

Set the worktable and low

single pressing should

ide to be vulcanized b

imensions of the work ta

l

l1

2m α

Minimum l = 2m + α l1 ≤ 50mm

nized press is used other th of the vulcanizing press.

Lower Frame

er heat plate of vulc

make the vulcanizati

y one press, use

ble are shown below

l1

L+Min.0.3m

VulcanizingPress

B*α

an 22.5o, then α shou

Hydraulic Pressure Plate

Work Table

5

anizing press on the same level.

on. In case the splice area is too

two or three vulcanizes with a

overspread

steel plate

and apply

single

pressing.

:

Work Table

2m

≥ Belt width + 0.2m = B x 0.414

ld be determined according to

6

(2) Overlap both sides of belt on the vulcanizing press.

B. FORMING

(1) Determination of center line.

Figure 2: Determine the center line

Belt

Vulcanizing PressWork Table Work Table

Belt Travel

1m 1m0.5m

B/2

B/2

0.5m1m 1m

BeltWidth

B/2

B/2 B/2

B/2

B/2 B/2 B/2

B/2B/2B/2

7

(2) Determination of cut-off line and base line.

(3) Cut belt along the cut-off line with bolt clipper.

It is advisable to lift up one side of the belt, so that cutting becomes easier.

(4) Peel off top and bottom rubber covers using Tirfor (tugging tool) and knife.

8

(5) Draw lines on the exposed area for both belt ends using the measured dimensions as

specified below.

(6) Cut the rubber between steel cords by inserting knife.

Remove the rubber around steel cord by knife.

In case of partial replacement or re-splicing, it is advisable to remove the aged rubber

around steel cord as much as possible with wire wheels grinder. Take care not to

damage steel cords.

(7) Buff a 25mm wide strip area and the surface of the covers approx. 50mm with the wire

wheel grinder.

Buff the Corner Rubber

25

S+15d+125

S50

15d+50

25

2S+19d+140

2S+4d+1550

15d+50

One-step method Two-step method

9

(8) Cut steel cords to the specified length.

Mark three center points at intervals of 500mm on both sides. Then, line up the sides

provisionally, measuring the distance l1 and l2 which must be the same.

(9) After buffing, lay a polyethylene sheet underneath splicing area and clean the splice

area with toluene. Apply a sufficient amount of rubber cement to the steel cords. Allow it

to dry thoroughly. It is recommendable to use a hot air-blower in order to accelerate

drying.

S+15d+75

S

15d+50

25

One-step method

2S+19d+90

2S+4d+15

15d+50

25

Two-step method

10

(10) Prepare bottom cover gum sheet and tie gum sheet. Lay tie rubber on cover rubber.

Roll on the rubber with roller. Poke tie rubber with an awl on entire surface to discharge

air. Total thickness of gum sheets is thicker than the actual bottom cover of the belt by

0.5mm.

(11) Mark three center points on each side of belting, and line up both sides so that all points

are in a straight line. After lining up, lay prepared bottom and tie gum on work table.

Then fix belt to the work table.

Cover Gum (W-10) Tie rubber (W-25)

L

L+100

Cut this portionCut this portion

Steel Cord

Bottom Cover

L+Min. 0.3m

Fix belt to the worktable

x x x2.5m

x x x2.5m

11

(12) Lay steel cords located at the center of the belt with the butted ends meeting. Next lay

alternating cables down and continue alternating to the edges of the belt. Fills tie gum

between cords, starting at the center and continue to the belt edges. Every 5-10 cords

check alignment by using string.

(13) Put tie gum and cover gum in order.

Carefully roll out each material so that air pockets will not occur between the

overlapped layers.

Tie GumA - A’

Tie Gum

EdgeRubber= Cover Gum

Put edge rubber on both sides of the

Cover Gum

Tie Gum

12

(14) Cut off the surplus edge portion. Poke small holes on the entire splice surface to

discharge air by using an awl.

(15) Check the finish thickness of the formed area. Make sure that the thickness of the

formed area is thicker than the belt by 1.0mm to 1.5mm. If not, add sufficient tie gum in

step (13).

13

(16) Mark the joint number on the top cover with white rubber. The joint numbers should be

provided consecutively in the direction of the running belt.

(17) Place a releasing fabric on both top and bottom covers. Make sure that the fabric is set

without wrinkles.

C. VULCANIZING

(1) Set edge former next to the belt edges.

Edge formers must be made of steel and 0.5 to 1.0mm thinner than the thickness of the

belt.

Edge Former

14

(2) After spreading out the releasing fabric on the entire splice area, assemble upper heat

plate and upper frame. Hand tighten the stay-bolts.

Clamp the entire equipment by tightening stay-bolts located at the both sides of the

press.

(Make sure the upper heat plate and frame align exactly with the lower plates and

frame)

(3) Connect the hose with the hydraulic pressure plate and the electric wire with the heat

plate, respectively. Apply water pressure between 10 and 12kg/cm2. When the pressure

exceeds 12kg/cm2, adjust it by using an air exhaust valve located in the water pressure

pump.

(4) Switch on the electricity and vulcanize the belt for a predetermined time at a

temperature of 145oC ±5 oC.

General Belt

Belt Thickness (mm) vs Curing Time (min)Cooling

Temperature<=15mm <=25mm <=30mm <=35mm

Temperature( oC )

Pressure( kg/cm2 ) ( oC )

8~ 1050 min 60 min 70 min 80 min 145 +/- 5

(0.8~1.0 MPa)<80

Heat Resistant Belt

TypeBelt Thickness (mm) vs

Curing Time (min)Cooling

Temperature

<=15mm <=21mm <=25mm

Temperature( oC )

Pressure( kg/cm2 )

( oC )

F-110 25 35 45F110-STF

25 35 45

A-110 25 35 45

8~10

SF-150 60 65 70

WF-100 NA NA NA

145+/- 5

SF-180 40 60 60 165(<=20), 175(>20) +10/ -5

A-2000 40 60 60 165(<=20), 175(>20) +10/ -5

(0.8~1.0MPa)

<120

* The vulcanizing time for a thicker belt, which is not specified above should be determined on

all such occasions.

(5) After vulcanization, cool down the belt below 120 oC without loosing the pressure.

15

D. FINISHING

When the vulcanization is finished, disassemble the press and check the appearance of the

splice area.

The protruded portion at the edges of rubber cover should be cut off by scissors or knife, and

finish with a disk sander.

E. PRECAUTIONS

(1) The worktable and the lower side of the vulcanizing press should be installed

respectively before working and maintained at the same level.

(2) Lining up of the formed ends should be made with special care.

(3) Lapping of the materials should be made after cleaning the surface with solvent in any

case.

(4) Arranging of the steel cords should always be made straight.

(5) The thickness of materials to be used must be adjusted so that the thickness of the

splice area before vulcanizing may not exceed more than 1.1mm compared with the

(6) belt. To measure thickness, use such device as slide calipers or dial thickness gauge.

(7) Inspection of vulcanizing press

Inspection of vulcanizing press is recommendable periodically at least once a year

especially on temperature and pressure distribution. Manuals on how to inspect the

press are available upon request.