JP2009035373A - Steel cord conveyer belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel cord conveyor belt capable of reducing the traveling resistance and saving the energy by suppressing the ride-over resistance of a carrier roller occupying a high ratio of the traveling resistance. <P>SOLUTION: The belt strength K<SB>n</SB>(N/mm) and the sectional area A (mm<SP>2</SP>) obtained from the nominal cord diameter of a steel cord satisfy inequalities 90≤K<SB>n</SB>/A≤150. A lower side cover rubber 1b is formed by using a rubber with low-loss factor of ≤0.08, and a reinforcing cloth 3 is embedded in the lower side cover rubber 1b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technology related to a conveyor belt in which a core body of a steel cord is embedded.

Conventionally, various attempts have been made to reduce CO ₂ emissions as a measure to prevent global warming. For example, technological developments for improving fuel efficiency to reduce exhaust gas from automobiles and energy savings in facilities such as buildings and factories are being promoted. As part of such efforts, attempts have been made to reduce the power consumption of the belt conveyor by reducing the energy consumption of the belt conveyor, that is, by reducing the running resistance of the conveyor belt. Specifically, in the conveyor belt in which the core body canvas is embedded, the reinforcing canvas is embedded on the upper side and / or the lower side of the core body canvas with the central part in the belt width direction, and the belt width direction center part. Conveyor belts with increased rigidity have been put to practical use (see, for example, Patent Document 1). When this conveyor belt passes through the three-point carrier roller, the belt width direction center portion is not bent and is maintained in a substantially flat state, so that the carrier roller overcoming resistance is reduced and the running resistance is reduced. . In Patent Document 1, a proposal has been made to use a rubber material having a small loss factor of viscoelastic characteristics and a small friction coefficient in order to further suppress the resistance of the carrier roller to cross over.
JP 2004-18202 A (page 3, FIGS. 1 and 2)

  The conveyor belt of the above-mentioned patent document 1 is a technology corresponding to a conveyor belt in which a canvas is embedded as a core body. However, a reduction in running resistance is also required for a conveyor belt embedded in a steel cord as a core body. It has been.

  Accordingly, an object of the present invention is to provide a steel cord conveyor belt that can reduce the running resistance by reducing the resistance over the carrier roller, which occupies a high proportion of the running resistance, and can save energy.

The steel cord conveyor belt according to claim 1,
(1) The belt strength K _n (N / mm) and the cross-sectional area A (mm ² ) obtained from the nominal cord diameter of the steel cord should satisfy the relationship of 90 ≦ K _n / A ≦ 150.
(2) The bottom cover rubber shall be a low loss coefficient rubber having a loss coefficient of 0.08 or less.
(3) A reinforcing cloth is embedded in the bottom cover rubber.
It is characterized by.

According to the steel cord conveyor belt of claim 1, the belt strength K _n and the cross-sectional area A satisfy the relationship of 90 ≦ K _n / A ≦ 150 as described in (1) above. Thus, the relationship between the nominal cord diameter and the cord pitch can be made to be a relationship suitable for a joint while reducing the resistance of the carrier roller to cross over.

  That is, when the steel cord conveyor belt passes through the carrier roller, the lower surface cover rubber is compressed and deformed. However, since the lower surface cover rubber is a viscoelastic body, energy loss due to deformation occurs. This energy loss becomes the resistance of the steel cord conveyor belt to climb over the carrier roller.

Therefore, if the relationship of 90 ≦ K _n / A is satisfied, the nominal cord diameter and the cord pitch can be reduced, and the stress concentrated between the steel cord and the carrier roller can be dispersed and relaxed. it can. As a result, the surface pressure between the lower surface cover rubber and the carrier roller is reduced, the deformation of the lower surface cover rubber is suppressed, and the overcoming resistance of the roller is reduced.

In addition, by satisfying the relationship of K _n / A ≦ 150, it is possible to avoid the relationship that the nominal chord diameter and the chord pitch cannot be substantially jointed. That is, if K _n / A exceeds 150, the nominal cord diameter and the cord pitch become too small, and the distance between the steel cords cannot be secured at the joint portion. This is because it becomes impossible to joint, or the arrangement of the steel cords in the joint portion becomes very complicated in order to ensure strength, and the joint portion becomes long and the joint is substantially impossible. From the viewpoint of joint workability and savings in belt usage, it is desirable for the joint part to have sufficient strength and a short length. The joint structure is simple from the viewpoint of joint workability. desirable.

The relationship between the nominal cord diameter and the cord pitch is defined by belt strength K _n / cross-sectional area A for the following reason. That is, if the tensile strength per one of the steel cords is F _bs , the belt width of the steel cord conveyor belt is b, the number of driven steel cords is n, and the cord pitch is p, the belt strength K _n Is expressed by the following equation.

K _n = F _bs × n / b (I)
In the above equation (1), the reciprocal of n / b, that is, although there is a slight error because the steel cord conveyor belt has ears, b / n corresponds to the cord pitch p, and the following (II) It can be expressed by a formula.

K _n = F _bs / p (II)
The belt strength K _n is equal to the predetermined belt strength K by changing the cord pitch p when the tensile strength F _bs per steel cord is constant, that is, when the diameter of the steel cord is the same. _n can be secured. In addition, when the cord pitch p is constant, the tensile strength F _bs per _piece of the steel cord is proportional to the cross-sectional area A of the steel cord. The belt strength K _n can be obtained. Even when the nominal cord diameter is the same, the actual cross-sectional area is different if the wire structure is different, and the tensile strength F _bs per one of the steel cords is different. The diameter of the steel cord is indicated by the nominal cord diameter because it is considered that the influence of the difference is small.

Therefore, Table 1 (JIS standard) and Table 2 (ISO standard) show the relationship between the belt strength _Kn and the cross-sectional area A / code pitch p in the JIS standard and ISO standard. Moreover, when the relationship shown in Table 1 and Table 2 is shown with a scatter diagram, it will become like FIG. 1, the vertical axis to the cross-sectional area A / code pitch p, and the horizontal axis and the belt strength K _n.

According to the scatter diagram of FIG. 1, the value of the cross-sectional area A / cord pitch p with respect to the belt strength K _n is substantially the same straight line, and the belt strength K _n and the cross-sectional area A / cord pitch p are proportional. You can see that Therefore, since the belt specifications are generally designed based on the belt strength, the relationship between the nominal cord diameter and the cord pitch p is defined as belt strength K _n / cross-sectional area A. The reason for this definition is that, for example, if the cross-sectional area A / belt strength K _{n is used} , it becomes a numerical value after the decimal point and is difficult to handle.

In addition to the configuration of (1) above, if the bottom cover rubber is a low loss coefficient rubber having a loss factor of 0.08 or less as in (2), energy absorption of the bottom cover rubber is suppressed, and the bottom cover rubber Energy loss due to rubber deformation can be reduced. Therefore, the resistance of the carrier roller to get over can be greatly reduced.

  This low loss coefficient rubber has a loss coefficient (also referred to as loss tangent) of 0.08 determined in accordance with JIS (Japanese Industrial Standard) K6394 vulcanized rubber and thermoplastic rubber (how to determine dynamic properties) general guidelines. It is a rubber that hardly absorbs the following energy. The loss coefficient (expressed by tan σ) can be expressed by tan σ = E ″ / E ′ where the storage elastic modulus is E ′ and the loss elastic coefficient is E ″. The various conditions are shown.

Further, as described in (3) above, if the reinforcing cloth is embedded in the lower surface cover rubber, the stress concentration generated between the steel cord and the carrier roller can be dispersed and reduced in the lower surface cover rubber. it can. As a result, the surface pressure between the lower surface cover rubber and the carrier roller is reduced, and deformation of the lower surface cover rubber is suppressed, so that energy loss is reduced and the resistance of the carrier roller to get over is reduced.

  The reinforcing cloth may be easily bent according to the trough angle when the steel cord conveyor belt passes through the trough type carrier roller. For example, the reinforcing cloth of nylon fiber having a large elongation and flexibility. Etc. are suitable.

  The steel cord conveyor belt according to claim 2 is characterized in that a reinforcing cloth is embedded over the entire width of the belt.

  According to the steel cord conveyor belt of this second aspect, stress concentration generated between the steel cord and the carrier roller can be dispersed and alleviated over the entire width of the lower surface cover rubber. The effect of reducing the surface pressure with the carrier roller is improved.

The steel cord conveyor belt according to claim 3 is characterized in that the belt strength K _n and the cross-sectional area A satisfy the relationship of 100 ≦ K _n / A ≦ 130. According to the steel cord conveyor belt of the second aspect, the relationship between the nominal cord diameter and the cord pitch makes it possible to perform a joint with a length equivalent to that of the conventional one while reducing the overcoming resistance of the carrier roller. .

  The steel cord conveyor belt according to the first aspect can significantly reduce running resistance as compared with the conventional steel cord conveyor belt without complicating the joint operation. Therefore, it can be driven with a small power, and an operation with a high energy saving effect becomes possible. In addition, since the running resistance is reduced, the belt safety factor can be increased while maintaining the same belt strength as the conventional one. Further, since the diameter of the steel cord is reduced, the total belt thickness can be reduced, and the amount of rubber material used can be saved.

  According to the steel cord conveyor belt of the second aspect, the effect of lowering the surface pressure between the lower surface cover rubber and the carrier roller is improved and it is possible to travel with less resistance, so that the energy saving effect can be improved.

  While the steel cord conveyor belt of claim 3 has joint workability equivalent to that of the conventional steel cord conveyor belt, the same effects as the steel cord conveyor belt of claim 1 or 2 such as energy saving effect, improvement of safety factor, saving of rubber material, etc. Demonstrate.

  An embodiment of a steel cord conveyor belt according to the present invention will be described with reference to FIGS.

  The steel cord conveyor belt 1 (hereinafter also referred to as the conveyor belt 1) is a conveyor belt in which a plurality of steel cords 2 are embedded as shown in the belt width direction sectional view of FIG. The steel cord 2 is embedded over the entire length of the conveyor belt 1 and is provided in parallel to the belt length direction X and at a constant pitch in the belt width direction Y. Cover rubbers 1a and 1b (upper cover rubber 1a and lower cover rubber 1b) are respectively provided above and below the steel cord 2, and the lower cover rubber 1b is made of a low-loss coefficient rubber having the composition shown in Table 4. It has been.

This low loss coefficient rubber indicates a rubber having a loss coefficient tanσ of 0.05 determined in accordance with the general guidelines of vulcanized rubber and thermoplastic rubber (how to obtain dynamic properties) of JIS standard (Japanese Industrial Standard) K6394. Yes. Table 5 shows various conditions when the loss coefficient tanσ is obtained.

Since this low-loss coefficient rubber is a rubber that hardly absorbs energy, energy loss when the conveyor belt 1 rides over the carrier roller can be suppressed, and the ride-over resistance can be reduced.

  In addition, a reinforcing cloth 3 made of nylon fibers is embedded in the intermediate layer of the bottom cover rubber 1b over the entire width. Thereby, the stress concentration generated between the steel cord 2 and the carrier roller in the lower surface cover rubber 1b can be dispersed and alleviated over the entire width of the lower surface cover rubber 1b. Therefore, the surface pressure between the surface cover rubber 1b and the carrier roller is reduced, the deformation of the lower surface cover rubber 1b is suppressed, the energy loss when the conveyor belt 1 passes over the carrier roller is reduced, and the resistance to overcoming is reduced. Since the nylon fiber has a large elongation and is flexible, when the conveyor belt 1 passes through the trough-type carrier roller, it is easy to bend according to the trough angle. Moreover, since the nylon fiber has high strength, the conveyor belt 1 is excellent in durability.

The conveyor belt 1, the belt strong and K _n, if the cross-sectional area of the steel cord 2 obtained from the nominal cord diameter and A, are configured to satisfy the relation 90 ≦ K _n / A ≦ 150 . If the belt strength K _n / cross-sectional area A satisfies this condition, the size of the nominal cord diameter and the cord pitch can be reduced within a range suitable for the joint while reducing the resistance of the carrier roller to cross over. .

That is, when the conveyor belt 1 passes through the carrier roller, the lower surface cover rubber 1b is compressed and deformed. Usually, since the lower surface cover rubber 1b is a viscoelastic body, energy loss due to this deformation occurs. This energy loss becomes a resistance to overcoming when the conveyor belt 1 passes over the carrier roller, and is a factor of running resistance of the conveyor belt 1. Therefore, the stress concentrated between the steel cord 2 and the carrier roller can be dispersed and alleviated by satisfying the relationship 90 ≦ K _n / A ≦ 150 between the belt strength K _n and the cross-sectional area A. it can. As a result, the surface pressure between the lower surface cover rubber 1b and the carrier roller is reduced, and the deformation of the lower surface cover rubber 1b is suppressed, so that the resistance over the carrier roller is reduced.

If K _n / A is less than 90, the size of the nominal cord diameter and the cord pitch cannot be reduced to such an extent that an energy saving effect can be expected, and if K _n / A exceeds 150, the nominal cord diameter and the cord pitch can be reduced. The cord pitch becomes too small, and the distance between the steel cords 2 cannot be secured at the joint. Then, it becomes impossible to joint, or in order to secure strength, it is necessary to have three or more overlapping joints, the arrangement of the steel cord 2 becomes very complicated and the joint part becomes long, substantially This is because joints are impossible.

  Next, the traveling test result obtained by measuring the resistance that the traveling conveyor belt 1 receives when passing over the carrier roller will be described.

  As shown in FIG. 2 (b), the test apparatus 10 used for this running test is arranged such that a driving pulley 11 and a driven pulley 12 having a diameter of 500 mm are spaced apart by 3000 mm, and an endless conveyor belt 1 is disposed between these pulleys. It is designed to hang around. A flat carrier roller 13 is arranged at one location on the carrier side, and this carrier roller 13 is placed on a movable carriage 14 that can reciprocate in the belt length direction of the conveyor belt 1 wound around pulleys. It is fixed. A load cell 15 is arranged on the drive pulley 11 side of the moving carriage 14 so that the load applied to the moving carriage 14 when the moving carriage 14 is pushed in the traveling direction of the conveyor belt 1 can be measured. Above the carrier roller 13, a load device 16 that applies a vertical load to the conveyor belt 1 is disposed. A plurality of rollers 17 are arranged on the contact surface of the load device 16 with the conveyor belt 1 so that a vertical load can be applied without affecting the running of the conveyor belt 1.

  A conveyor belt 1 having a width of 500 mm is attached to such a test apparatus 1, and a vertical load of 5 kN / m (per 1 m in the width direction) is applied while running at a belt speed of 170 m / min, and the load received by the movable carriage 14 is measured. Then, the resistance when the conveyor belt 1 passed over the carrier roller 13 was examined. In addition to the four types of conveyor belts according to the present invention (Examples 1 to 4) and the standard specification conveyor belts (Comparative Example 2), the running test includes Comparative Example 2 This was carried out for five types of conveyor belts (Comparative Examples 1, 3 to 6) in which the specifications of the conveyor belts were partially changed. The thickness of the lower surface cover rubber of each example and comparative example is set according to the cord diameter of the steel cord as a guide, and for the conveyor belts of comparative examples 4 to 6 and each example, the running resistance reduction effect is expected, The belt strength was 2250 N / mm, one rank lower than the standard specification. Table 6 shows the specifications of each example and comparative example conveyor belt.

In Table 4, “normal” of the bottom cover rubber type indicates a rubber having a loss factor tan σ 0.15 mainly composed of natural rubber used in general-purpose ordinary conveyor belts. Yes. In addition, the measurement result of the said running test is described in Table 4 as a running resistance index. The running resistance index is based on the load measured in the running test of the conveyor belt of Comparative Example 2, and is expressed as an index with this load as 100.

  Comparing Comparative Example 1 and Comparative Example 2, Comparative Example 1 has a larger nominal cord diameter and cord pitch and a larger running resistance index. Therefore, it can be inferred that increasing the nominal cord diameter and cord pitch is a factor that increases the resistance of the carrier roller to climb over.

  Comparing Comparative Example 3 and Comparative Example 2, the nominal cord diameter and cord pitch are the same, but in Comparative Example 3, the running resistance index is halved. Therefore, it can be inferred that the use of a low-loss coefficient rubber for the bottom cover rubber will greatly reduce the resistance of the carrier roller to climb over.

  If Comparative Example 4 and Comparative Example 5 are compared, Comparative Example 5 has a smaller number of running resistance papers. Therefore, it can be inferred that the resistance of the carrier roller overcoming decreases as the nominal cord diameter and cord pitch are reduced.

  In Comparative Example 6, the nominal cord diameter and the cord pitch became too small, and it was necessary to perform an overlap joint of three or more stages. Therefore, the structure and joint work became complicated and it was not practical, so the running test was omitted.

  Comparing Comparative Example 4 and Example 1, the number of running resistance papers in Example 1 is smaller. Therefore, it can be inferred that embedding the reinforcing cloth in the lower cover rubber has an effect of reducing the resistance of the carrier roller overcoming.

  When Examples 1 to 4 are compared, it is presumed that the smaller the nominal cord diameter and the cord pitch, the smaller the running resistance. Moreover, the conveyor belts of all the examples are 60% or less compared to the running resistance index of Comparative Example 2, and the conveyor belts of Examples 1 to 4 according to the present invention greatly reduce the running resistance. It is inferred that

Looking at these comparative studies and the relationship between the belt strength K _n / cross-sectional area A and the running resistance index, if K _n / A is in the range of 90 to 150, the nominal cord diameter and cord pitch are It is inferred that the size is such that the rolling resistance of the roller is greatly reduced, that is, the vehicle can run with very little resistance. Moreover, if the joint length of the comparative example 2 is used as a guide, it is a size that can be jointed practically. In particular, if K _n / A is in the range of 100 to 130, the joint is equivalent to the comparative example 2. Therefore, it is preferable that the joint structure can be complicated and the workability can be prevented from being lowered.

Next, the results of analysis by FEM (finite element method) analysis will be described.
1) Specification of conveyor belt The conveyor belts of Examples 1 to 4 and Comparative Examples 1 to 6 used in the running test.
2) Usage conditions Carrying amount 1200t / h
Belt speed 170m / min
Specific gravity 1.6
Tension 112.5kN (Belt width 1/2 model, full width 225kN equivalent)
S. F. = 10, belt strength set from 2500 N / mm Carrier roller diameter 114.3 mm
Carrier roller pitch 1.5m
3) Analytical model Fig. 3 shows the analytical model. This analysis model shows a state in which the conveyor belt 102 is running on a three-point carrier roller 101, and the center in the belt width direction is cut in parallel to the belt length direction. The code | symbol 103 in the figure has shown the steel cord.
4) Output items The total value of strain energy of the rubber part element from the center of the steel cord to the bottom cover rubber surface was output. It is confirmed that the value obtained by multiplying the total value of the strain energy by the loss factor is the loss energy, and this value has a correlation with the running resistance. In addition, the loss energy of Comparative Example 2 is expressed as an index with 100 as the loss energy.
5) Analysis results Table 7 shows the FEM analysis results.

Comparing Comparative Example 1 and Comparative Example 2, Comparative Example 1 has a larger nominal cord diameter and cord pitch, and a larger loss energy index. Further, according to the Mises stress distribution diagram in the belt cross section, the comparative example 1 (FIG. 4A) has a wider red to yellow region than the comparative example 2 (FIG. 4B), and the stress concentration is high. You can see that it has occurred. The stress is shown in red, yellow, green and blue in order from the highest. Therefore, it can be inferred that increasing the nominal cord diameter and cord pitch is a factor that increases the resistance of the carrier roller to climb over.

  Comparing Comparative Example 3 and Comparative Example 2, in the Mises stress distribution diagram, in Comparative Example 3 (FIG. 5A) and Comparative Example 2 (FIG. 4B), the input conditions of the FEM analysis are Although some stress-strain characteristics are almost the same, there is no difference, but the loss energy index in Comparative Example 3 is reduced to about ３ due to the difference in loss coefficient due to the difference in the bottom cover rubber. Therefore, since the nominal cord diameter and cord pitch are the same, it is surmised that if a low-loss coefficient rubber is used for the lower surface cover rubber, the overcoming resistance of the carrier roller is greatly reduced.

  Comparing Comparative Example 4 and Comparative Example 5, the loss energy index of Comparative Example 5 is smaller. Further, according to the Mises stress distribution diagram, the comparative example 5 (FIG. 6A) has a smaller red to yellow region than the comparative example 4 (FIG. 5B), and the stress concentration is relaxed. I understand that. Therefore, if the nominal cord diameter and the cord pitch are reduced, it is possible to expect a decrease in the resistance over the carrier roller.

  Comparative Example 6 shows the smallest value of the loss energy index, and the red to yellow region is not seen even in the Mises stress distribution diagram (FIG. 6B), and the stress concentration is greatly relaxed. I understand. However, since the nominal cord diameter and the cord pitch are too small and it is necessary to perform an overlap joint of three or more stages, the structure and joint work become complicated, which is not practical.

  Comparing Comparative Example 4 and Example 1, the loss energy index of Example 1 is smaller. Further, according to the Mises stress distribution diagram, in Example 1 (FIG. 7A), the red to yellow region is hardly seen, and the stress concentration is larger than that in Comparative Example 4 (FIG. 5B). It can be seen that is relaxed. Therefore, it is presumed that when the reinforcing cloth is embedded in the lower surface cover rubber, the resistance of the carrier roller overcoming decreases.

  Comparing Examples 1 to 4, the loss energy index is smaller when the nominal cord diameter and cord pitch are made smaller. Further, according to the Mises stress distribution diagrams (FIGS. 7A, 7B to 8A, 8B), the difference is small, but the smaller the nominal cord diameter and cord pitch, the green to blue region. It can be seen that the stress concentration is more relaxed. That is, it can be inferred that reducing the nominal cord diameter and the cord pitch reduces the resistance of the carrier roller overcoming. Moreover, the conveyor belts of any of the examples are 60% or less compared to the loss energy index of Comparative Example 2, and the conveyor belts of Examples 1 to 4 according to the present invention greatly reduce the loss energy index. Inferred to be a belt.

Looking at these comparative studies, the relationship between the belt strength K _n / cross-sectional area A and the loss energy index and the Mises stress distribution diagram, if K _n / A is in the range of 90 to 150, the nominal cord diameter and It is presumed that the cord pitch is a size that greatly reduces the resistance of the carrier roller overcoming, that is, extremely low running resistance. Further, if the length of the joint of Comparative Example 2 is used as a guideline, it is a size that can be practically jointed. In particular, if K _n / A is in the range of 100 to 130, the joint is equivalent to that of Comparative Example 2. Since it can be performed by the length, it is possible to avoid complication of the joint structure and deterioration of workability.

The scatter diagram which shows the relationship between a code | cord | chord cross-sectional area, code | cord | chord pitch, and belt strength based on the numerical value prescribed | regulated to JIS standard and ISO standard. (A) Belt width direction sectional drawing of the conveyor belt which concerns on this invention. (B) The conceptual diagram of the driving | running | working test machine shown in the best form for implementing invention. An analysis model that analyzes the distribution of stress. (A) Mises stress distribution diagram of Comparative Example 1. (B) Mises stress distribution diagram of Comparative Example 2. (A) Mises stress distribution diagram of Comparative Example 3. (B) Mises stress distribution diagram of Comparative Example 4. (A) Mises stress distribution diagram of Comparative Example 5. (B) Mises stress distribution diagram of Comparative Example 6. (A) Mises stress distribution diagram of Example 1. FIG. (B) Mises stress distribution diagram of Example 2. (A) Mises stress distribution diagram of Example 3. (B) Mises stress distribution diagram of Example 4.

Explanation of symbols

1 Steel cord conveyor belt (conveyor belt)
1a Top cover rubber 1b Bottom cover rubber 2 Steel cord 3 Reinforcement cloth

Claims (3)

The belt strength K _n (N / mm) and the cross-sectional area A (mm ² ) determined from the nominal cord diameter of the steel cord satisfy the relationship of 90 ≦ K _n / A ≦ 150. A steel cord conveyor belt characterized by being a low loss coefficient rubber of 08 or less and having a reinforcing cloth embedded in the bottom cover rubber.   The steel cord conveyor belt according to claim 1, wherein the reinforcing cloth is embedded over the entire width of the belt. The steel cord conveyor belt according to claim 1, wherein the belt strength K _n and the cross-sectional area A satisfy a relationship of 100 ≦ K _n / A ≦ 130.