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(11) | EP 3 222 563 B9 |
| (12) | CORRECTED EUROPEAN PATENT SPECIFICATION |
| Note: Bibliography reflects the latest situation |
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CONVEYOR BELT FÖRDERBAND COURROIE TRANSPORTEUSE |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
Technical Field
[0001] The present invention relates to a conveyor belt, and more particularly relates to a conveyor belt capable of improving both wear resistance and impact resistance of an upper cover rubber in a compatible manner.
Background Art
[0002] A conveyor belt generally has a configuration in which an upper cover rubber is layered on an outer peripheral side of a core formed from a canvas layer or a steel cord layer, and a lower cover rubber is layered on an inner peripheral side of the core. An object to be conveyed is fed and placed onto the upper cover rubber and conveyed. The upper cover rubber is subject to great impact depending on the fed object to be conveyed. The impact causes damage to the upper cover rubber to progress over time. The damage to the upper cover rubber is significant in the case where the object to be conveyed has a sharp projection on a surface of the object to be conveyed.
[0003] The conveying speed of the conveyor belt is different from the speed of the fed object to be conveyed in a belt conveying direction. As a result, friction generates between the upper cover rubber and the object to be conveyed. Friction also generates between the upper cover rubber and the object to be conveyed while the object to be conveyed is conveyed. The friction causes wear on the upper cover rubber to progress over time.
[0004] When the damage and wear caused by the impact reach the core, the conveyor belt cannot be used. Accordingly, the upper cover rubber having improved impact resistance and wear resistance can extend the service life of the conveyor belt.
[0005] Conventionally, various conveyor belts have been proposed. Such conveyor belts achieve good wear resistance and impact resistance in a compatible manner (For example, Patent Document 1). Including the conveyor belt proposed in Patent Document 1, conveyor belts are known that have a configuration in which special rubber composition having good wear resistance and impact resistance is used as the upper cover rubber (paragraph [0145] of Patent Document 1). However, achieving good wear resistance and impact resistance in a compatible manner with single rubber composition is difficult. Conventional conveyor belts have a tendency in that one or both characteristics are improved insufficiently. US 2 252 836 A discloses the features of the preamble of claim 1.
Citation List
Patent Literature
Summary of Invention
Technical Problem
[0007] An object of the present invention is to provide a conveyor belt capable of improving both wear resistance and impact resistance of an upper cover rubber in a compatible manner.
Solution to Problem
[0008] To achieve the object described above, a conveyor belt of the present invention includes an upper cover rubber, a lower cover rubber, and a core. The core is embedded between the upper cover rubber and the lower cover rubber. The upper cover rubber includes a wear resistance layer and an impact resistance layer. The wear resistance layer and the impact resistance layer are layered in this order from an outer peripheral side of the conveyor belt. The wear resistance layer has a loss coefficient of from 0.03 to 0.25 and a loss elastic coefficient of from 0.20 MPa to 6.50 MPa at 20°C. The impact resistance layer has a loss coefficient of from 0.15 to 0.70 and a loss elastic coefficient of from 1.5 MPa to 30.0 MPa at 20°C.
Advantageous Effects of Invention
[0009] According to the present invention, the wear resistance layer for which each of a loss coefficient and a loss elastic coefficient is set to a specific range is provided as the upper cover rubber. As a result, the wear resistance layer can reduce wear caused by friction generated between the object to be conveyed and the upper cover rubber. The impact resistance layer for which each of a loss coefficient and a loss elastic coefficient is set to a specific range is provided as the upper cover rubber. As a result, the impact resistance layer can reduce damage caused by impact received from the object to be conveyed.
[0010] The wear resistance layer disposed on an outer peripheral side of the impact resistance layer protects the impact resistance layer from wear caused by the object to be conveyed. This is advantageous in exhibiting good impact resistance over an extended period of time. Meanwhile, the impact resistance layer disposed on an inner peripheral side of the wear resistance layer exhibits good impact resistance and absorbs impact caused by the fed object to be conveyed over an extended period of time, which reduces damage caused by the impact on the wear resistance layer. In this way, due to synergistic effects of the separately provided wear resistance layer having good wear resistance and impact resistance layer having good impact resistance, both the wear resistance and impact resistance of the upper cover rubber are sufficiently improved, which is advantageous in extending the service life of the conveyor belt.
[0011] A configuration is possible in which the wear resistance layer is disposed furthest out on a periphery of the upper cover rubber. In such a configuration, the wear resistance layer is disposed at a position making it come into direct contact with the object to be conveyed, which is the most advantageous in suppressing wear on the upper cover rubber.
[0012] The wear resistance layer has a configuration in which a layer thickness of the wear resistance layer is from 2 mm to 30 mm. In such a configuration, the layer thickness of the wear resistance layer is not excessive, which allows deterioration in bending resistance of the conveyor belt to be avoided and sufficient wear resistance to be obtained.
[0013] The impact resistance layer has a configuration in which a layer thickness of the impact resistance layer is from 2 mm to 30 mm. In such a configuration, the layer thickness of the impact resistance layer is not excessive, which allows deterioration in bending resistance of the conveyor belt to be avoided and sufficient impact resistance to be obtained.
[0014] A configuration is also possible in which the layer thickness of the impact resistance layer is greater at a central portion in a belt width direction than at both end portions in the belt width direction. A carrying side of the conveyor belt where the object to be conveyed is fed onto the upper cover rubber is trough-like. Accordingly, the upper cover rubber receives smaller impact from the fed object to be conveyed at the both end portions in the belt width direction than at the central portion in the belt width direction. In such a configuration, the impact resistance layer has a non-excessive layer thickness at both end portions in the belt width direction, which improves bending resistance of the conveyor belt and is advantageous in reducing weight. This can reduce the energy required for running of the conveyor belt.
Brief Description of Drawings
[0015]
FIG. 1 is an explanatory view illustrating a state where a conveyor belt of an embodiment of the present invention is stretched between pulleys.
FIG. 2 is a cross-sectional view taken along A-A in FIG. 1.
FIG. 3 is a cross-sectional view in a belt width direction illustrating a state where the conveyor belt in FIG. 1 is flat.
FIG. 4 is a cross-sectional view in a belt width direction illustrating a state where a conveyor belt according to another embodiment is flat.
Description of Embodiments
[0016] Below, description will be given of the conveyor belt of the present invention on the basis of embodiments illustrated in the drawings. A dot-dash line CL in FIGS. 3 and 4 indicates a center in the belt width direction.
[0017] A conveyor belt 1 according to an embodiment of the present invention illustrated in FIGS. 1 and 2 includes a core 2, an upper cover rubber 3, and a lower cover rubber 4. The upper cover rubber 3 is layered on an outer peripheral side of the core 2. The lower cover rubber 4 is layered on an inner peripheral side of the core 2. The core 2 is embedded between the upper cover rubber 3 and the lower cover rubber 4. These are integrated by vulcanization bonding. As described below, both end portions in the belt width direction of the core 2 may be an edge rubber made from a rubber material different from that of the upper cover rubber 3 and the lower cover rubber 4.
[0018] The conveyor belt 1 is stretched between a driving pulley 5 and a driven pulley 6 of a belt conveyor device. The core 2 is a member which bears the tension when the conveyor belt 1 is stretched. The core 2 is constituted by a fiber layer such as a canvas. Alternatively, the core 2 is constituted by a plurality of steel cords (steel cord layer) extending in a longitudinal direction parallel to the belt width direction. The material and the number of layers of the core 2 are determined according to the properties (rigidity, elongation, and the like) demanded with respect to the conveyor belt 1. A single layer, plural layer, or multilayer structure is employed for the fiber layer. A single layer structure is employed for the steel cord layer. A reinforcing layer is also embedded in the conveyor belt 1 as necessary.
[0019] The carrying side of the conveyor belt 1 is supported by support rollers 7 in manner in which both end portions in the belt width direction of the conveyor belt 1 are inclined at a predetermined trough angle G1 with respect to a horizontal direction, giving the conveyor belt 1 a trough-like shape. The support rollers 7 are in contact with the lower cover rubber 4 and roll. Meanwhile, on a return side of the conveyor belt 1, the upper cover rubber 3 is supported by the support rollers 7 in a state in which the conveyor belt 1 is substantially flat in the belt width direction. An object to be conveyed C is fed onto the upper cover rubber 3 of the conveyor belt 1 on the carrying side.
[0020] As illustrated in FIG. 3, the upper cover rubber 3 is constituted by a wear resistance layer 3a and an impact resistance layer 3b. The wear resistance layer 3a and the impact resistance layer 3b are layered in this order from an outer peripheral side of the conveyor belt. In this embodiment, the wear resistance layer 3a is disposed furthest out on the periphery of the upper cover rubber 3. An inner peripheral surface of the wear resistance layer 3a and an outer peripheral surface of the impact resistance layer 3b are vulcanization bonded. An inner peripheral surface of the impact resistance layer 3b and an outer peripheral surface of a core 2 are vulcanization bonded with an adhesive rubber interposed therebetween. Each of a layer thickness ta of the wear resistance layer 3a and a layer thickness tb of the impact resistance layer 3b is constant in the belt width direction.
[0021] An inner peripheral surface of the lower cover rubber 4 and an outer peripheral surface of the core 2 are vulcanization bonded with an adhesive rubber interposed therebetween. A known configuration is employed for the lower cover rubber 4.
[0022] The wear resistance layer 3a exhibits good wear resistance as compared with the other portions. A loss coefficient Tanδ at 20°C of the wear resistance layer 3a is set to be from 0.03 to 0.25. A loss elastic coefficient of the wear resistance layer 3a is set to be from 0.2 MPa to 6.5 MPa. Preferably, a wear volume loss of the wear resistance layer 3a is preferably not greater than 50 mm3.
[0023] The wear resistance layer 3a having a loss coefficient Tanδ of less than 0.03 cannot ensure sufficient wear resistance performance and physical properties in normal state. The wear resistance layer 3a having a loss coefficient Tanδ of greater than 0.25 cannot ensure optimum wear resistance performance. The wear resistance layer 3a having a loss elastic coefficient of less than 0.2 MPa cannot ensure sufficient wear resistance performance and physical properties in normal state. The wear resistance layer 3a having a loss elastic coefficient of greater than 6.5 MPa cannot ensure optimum wear resistance performance.
[0024] The impact resistance layer 3b exhibits good impact resistance as compared with the other portions. A loss coefficient Tanδ at 20°C of the impact resistance layer 3b is set to be from 0.15 to 0.70. A loss elastic coefficient of the impact resistance layer 3b is set to be from 1.5 MPa to 30.0 MPa.
[0025] The impact resistance layer 3b having a loss coefficient Tanδ of less than 0.15 cannot ensure sufficient impact resistance. The impact resistance layer 3b having a loss coefficient Tanδ of greater than 0.70 may be easily scratched on the rubber surface, which results in shorter service life (service lifetime). The impact resistance layer 3b having a loss elastic coefficient of less than 1.5 MPa cannot ensure sufficient impact resistance. The impact resistance layer 3b having a loss elastic coefficient of greater than 30.0 MPa may be easily scratched on the rubber surface, which results in shorter service life (service lifetime).
[0026] A loss coefficient Tanδ and a loss elastic coefficient prescribed by the present invention are values obtained by measuring strip-shaped test pieces (20 mm in length x 5 mm in width x 2 mm in thickness) cut out from vulcanized rubber sheets of which the wear resistance layer 3a and the impact resistance layer 3b are formed using a viscoelastic spectrometer specified by JIS K 6394 (for example, a spectrometer manufactured by Toyo Seiki Seisaku-Sho, Ltd.). The measurement is performed under conditions of the test pieces being at 10% strain (initial strain) and subjected to a vibration at ±2% amplitude and a frequency of 10 Hz at a measurement temperature of 20°C.
[0027] A wear volume loss prescribed by the present invention is a value obtained by measuring a test piece (16 mm in diameter, 6 mm in thickness) cut out from a vulcanized rubber sheet of which the wear resistance layer 3a is formed in accordance with a DIN wear test method (A method) specified by JIS K 6264-2:2005 (ISO4649). In this measurement, the wear volume of the test piece is measured at a temperature of 23°C.
[0028] In the present invention, the wear resistance layer 3a for which the loss coefficient Tanδ and the loss elastic coefficient are set to a specific range is provided as the upper cover rubber 3. As a result, the wear resistance layer 3a reduces wear caused by friction with the fed object to be conveyed C. The impact resistance layer 3b for which the loss coefficient Tanδ and the loss elastic coefficient are set to a specific range is provided as the upper cover rubber 3. As a result, the impact resistance layer 3b reduces wear caused by friction with the fed object to be conveyed C.
[0029] The wear resistance layer 3a disposed on an outer peripheral side of the impact resistance layer 3b protects the impact resistance layer 3b from wear caused by the object to be conveyed C, which is advantageous in exhibiting good impact resistance over an extended period of time. Meanwhile, the impact resistance layer 3b disposed on an inner peripheral side of the wear resistance layer 3a exhibits good impact resistance and absorbs impact caused by the fed object to be conveyed C over an extended period of time, which reduces damage caused by impact on the wear resistance layer 3a. Therefore, the wear resistance layer 3a can exhibit good wear resistance over an extended period of time.
[0030] In this way, due to synergistic effects of the separately provided the wear resistance layer 3a having good wear resistance and the impact resistance layer 3b having good impact resistance, both characteristics are sufficiently improved. This is advantageous in extending the service life of the conveyor belt 1.
[0031] In a configuration such as one similar to this embodiment in which the wear resistance layer 3a is disposed furthest out on the periphery of the upper cover rubber 3, the wear resistance layer 3a is disposed at a position making it come into direct contact with the object to be conveyed C. This is the most advantageous in suppressing wear on the upper cover rubber 3.
[0032] Another layer may be disposed on the outer peripheral side of the wear resistance layer 3a. Another layer may also be disposed between the wear resistance layer 3a and the impact resistance layer 3b. Such a configuration in which the impact resistance layer 3b is disposed on the inner peripheral side of the wear resistance layer 3a is preferably so that the wear resistance layer 3a and the impact resistance layer 3b and their good characteristics influence each other, and synergistic effects can be exhibited.
[0033] The wear resistance layer 3a has a configuration in which the layer thickness ta of the wear resistance layer 3a is, for example, from 2 mm to 30 mm. In such a configuration, the layer thickness ta of the wear resistance layer 3a is not excessive, allowing deterioration in bending resistance of the conveyor belt 1 to be avoided. This is advantageous in reducing energy required for running of the conveyor belt 1. The wear resistance layer having a layer thickness ta of 2 mm or greater can have sufficient wear resistance.
[0034] The impact resistance layer 3b has a configuration in which the layer thickness tb of the impact resistance layer 3b is, for example, from 2 mm to 30 mm. In such a configuration, the layer thickness tb of the impact resistance layer 3b is not excessive, allowing deterioration in bending resistance of the conveyor belt 1 to be avoided. This is advantageous in reducing energy required for running of the conveyor belt 1. The impact resistance layer 3b having a layer thickness tb of 2 mm or greater can have sufficient impact resistance.
[0035] As illustrated in FIG. 4, a configuration is also possible in which a layer thickness tb1 of the impact resistance layer 3b at the central portion in the belt width direction is greater than a layer thickness tb2 at both end portions in the belt width direction. The carrying side of the conveyor belt 1 where the object to be conveyed C is fed onto the upper cover rubber 3 is trough-like. Accordingly, the upper cover rubber 3 receives smaller impact from the fed object to be conveyed C at the both end portions in the belt width direction than at the central portion in the belt width direction. Each of the end portions in the belt width direction is a portion ranging from a start point, which is located at the corresponding end portion in the belt width direction, to an end point, which is located at a position about from 10% to 20% of the belt width toward the central portion in the belt width direction from the start point.
[0036] Accordingly, the impact resistance layer 3b may have a thinner layer thickness at the both end portions in the belt width direction than at the central portion in the belt width direction. According to this embodiment, the impact resistance layer 3b has a non-excessive layer thickness tb at both end portions in the belt width direction, which improves bending resistance of the conveyor belt 1 and is advantageous in reducing weight. This can reduce the energy required for running of the conveyor belt 1.
[0037] In this embodiment, the layer thickness ta of the wear resistance layer 3a is constant in the belt width direction. The friction with the object to be conveyed C is smaller at the both end portions in the belt width direction than at the central part in the belt width direction similar to that of the impact resistance layer 3b. Therefore, the wear resistance layer 3a can have a greater layer thickness ta at the central part in the belt width direction than at the both end portions in the belt width direction.
Reference Signs List
an upper cover rubber (3) comprising:
a wear resistance layer (3a); and
an impact resistance layer (3b);
the wear resistance layer (3a) and the impact resistance layer (3b) being layered in this order from an outer peripheral side of the conveyor belt (1);a lower cover rubber (4); and
a core (2) embedded between the upper cover rubber (3) and the lower cover rubber (4); wherein
the wear resistance layer (3a) exhibits good wear resistance as compared with the other portions; whereinthe impact resistance layer (3b) exhibits good impact resistance as compared with the other portions;
characterized in that,
the wear resistance layer (3a) has a loss coefficient of from 0.03 to 0.25 and a loss elastic coefficient of from 0.20 MPa to 6.50 MPa at 20°C, the impact resistance layer (3b) has a loss coefficient of from 0.15 to 0.70 and a loss elastic coefficient of from 1.5 MPa to 30.0 MPa at 20°C,
a layer thickness of each of the wear resistance layer (3a) and the impact resistance layer (3b) is from 2.0 mm to 30.0 mm,
wherein the loss coefficient and the loss elastic coefficient are obtained by measuring strip-shaped test pieces, cut out from vulcanized rubber sheets of which the wear resistance layer (3a) and the impact resistance layer (3b) are formed, using a viscoelastic spectrometer specified by JIS K 6394, and
wherein the measurement is performed under conditions of the test pieces being at 10% initial strain and subjected to a vibration at ±2% amplitude and a frequency of 10 Hz at a measurement temperature of 20°C.
the wear resistance layer (3a) is disposed furthest out on a periphery of the upper cover rubber (3).
einen oberen Deckgummi (3), umfassend:
eine Abriebbeständigkeitsschicht (3a); und
eine Stoßfestigkeitsschicht (3b);
wobei die Abriebbeständigkeitsschicht (3a) und die Stoßfestigkeitsschicht (3b) in dieser Reihenfolge von einer äußeren Umfangsseite des Förderbands (1) aus geschichtet sind;
einen unteren Deckgummi (4); und
einen Kern (2), der zwischen dem oberen Deckgummi (3) und dem unteren Deckgummi (4) eingebettet ist; wobei
die Abriebbeständigkeitsschicht (3a) im Vergleich zu den anderen Abschnitten eine gute Abriebbeständigkeit aufweist; wobei
die Stoßfestigkeitsschicht (3b) im Vergleich zu den anderen Abschnitten eine gute Stoßfestigkeit aufweist; dadurch gekennzeichnet, dass
die Abriebbeständigkeitsschicht (3a) einen Verlustkoeffizienten von 0,03 bis 0,25 und einen elastischen Verlustkoeffizienten von 0,20 MPa bis 6,50 MPa bei 20 °C aufweist,
die Stoßfestigkeitsschicht (3b) einen Verlustkoeffizienten von 0,15 bis 0,70 und einen elastischen Verlustkoeffizienten von 1,5 MPa bis 30,0 MPa bei 20 °C aufweist,
eine Schichtdicke der Abriebbeständigkeitsschicht (3a) und der Stoßfestigkeitsschicht (3b) jeweils von 2,0 mm bis 30,0 mm beträgt,
wobei der Verlustkoeffizient und der Verlustelastizitätskoeffizient durch Messen streifenförmiger Teststücke erhalten werden, die aus vulkanisierten Gummiplatten ausgeschnitten sind, aus denen die Abriebbeständigkeitsschicht (3a) und die Stoßfestigkeitsschicht (3b) gebildet sind, wobei ein Viskoelastizitätsspektrometer gemäß JIS K 6394 verwendet wird, und
wobei die Messung unter Bedingungen durchgeführt wird, bei denen die Teststücke einer Anfangsbeanspruchung von 10 % und einer Vibration mit einer Amplitude von ±2 % und einer Frequenz von 10 Hz bei einer Messtemperatur von 20 °C ausgesetzt sind.
die Abriebbeständigkeitsschicht (3a) am weitesten außen am Umfang des oberen Deckgummis (3) angeordnet ist.
die Schichtdicke der Stoßfestigkeitsschicht (3b) in einem mittleren Teil in Bandbreitenrichtung größer ist als in den beiden Endabschnitten in Bandbreitenrichtung.
die Schichtdicke der Abriebbeständigkeitsschicht (3a) in einem mittleren Teil in Bandbreitenrichtung größer ist als in den beiden Endabschnitten in Bandbreitenrichtung.
un caoutchouc de couverture supérieur (3) comprenant :
une couche de résistance à l'usure (3a) ; et
une couche de résistance à l'impact (3b) ;
la couche de résistance à l'usure (3a) et la couche de résistance à l'impact (3b) étant déposées en couche dans cet ordre à partir d'un côté périphérique externe de la bande transporteuse (1) ;
un caoutchouc de couverture inférieur (4) ; et
une âme (2) noyée entre le caoutchouc de couverture supérieur (3) et le caoutchouc de couverture inférieur (4) ; dans laquelle
la couche de résistance à l'usure (3a) présente une bonne résistance à l'usure par comparaison avec les autres parties ; dans laquelle
la couche de résistance à l'impact (3b) présente une bonne résistance à l'impact par comparaison avec les autres parties ; caractérisée en ce que,
la couche de résistance à l'usure (3a) a un coefficient de perte allant de 0,03 à 0,25 et un coefficient élastique de perte allant de 0,20 MPa à 6,50 MPa à 20 °C,
la couche de résistance à l'impact (3b) a un coefficient de perte allant de 0,15 à 0,70 et un coefficient élastique de perte allant de 1,5 MPa à 30,0 MPa à 20 °C,
une épaisseur de couche de chacune de la couche de résistance à l'usure (3a) et de la couche de résistance à l'impact (3b) va de 2,0 mm à 30,0 mm,
dans laquelle le coefficient de perte et le coefficient élastique de perte sont obtenus en mesurant des pièces de test en forme de bandelette, découpées à partir de feuilles de caoutchouc vulcanisé desquelles la couche de résistance à l'usure (3a) et la couche de résistance à l'impact (3b) sont formées, en utilisant un spectromètre viscoélastique spécifié par JIS K 6394, et
dans laquelle la mesure est mise en œuvre dans des conditions des pièces de test étant à une déformation initiale de 10 % et soumises à une vibration à une amplitude de ±2 % et une fréquence de 10 Hz à une température de mesure de 20 °C.
la couche de résistance à l'usure (3a) est disposée le plus à l'extérieur sur une périphérie du caoutchouc de couverture supérieur (3).
l'épaisseur de couche de la couche de résistance à l'impact (3b) est plus grande au niveau d'une partie centrale dans une direction en largeur de bande qu'au niveau de l'une et l'autre des parties d'extrémité dans la direction en largeur de bande.
l'épaisseur de couche de la couche de résistance à l'usure (3a) est plus grande au niveau d'une partie centrale dans une direction en largeur de bande qu'au niveau de l'une et l'autre parties d'extrémité dans la direction en largeur de bande.
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.
Patent documents cited in the description