Rubber selection process

Abstract

A rubber selection method for selecting a rubber for use in a target object which, in use, experiences impact from an impacting object, wherein an impact test in which an impact element is subjected to free fall onto a sample of a variety of rubber types with different physical properties is carried out under prescribed test conditions; Data are collected for three quantities, including a loss energy absorbed by the sample when the impact element collides with the sample, a thermal energy generated at the sample, and an indentation amount in the sample by the impact element; and a particular sample is selected from the plurality of sample types based on a ranking of the superiority of the plurality of samples with respect to the sizes for which data were collected, wherein an optimal sample is selected from the plurality of sample types based on the ranking of superiority of the plurality of sample types with respect to each size and a priority order between each predetermined size.

Description

Technical field

[0001] The present invention relates to a rubber selection method, specifically to a rubber selection method that makes it possible to select a suitable rubber corresponding to the actual use of a target object such as a conveyor belt in selecting a rubber for the target object. State of the art

[0002] Various materials to be conveyed, including mineral raw materials such as iron ore and limestone, are transported via a conveyor belt. As the materials to be conveyed are fed onto the upper rubber layer of the conveyor belt, the upper rubber layer is subjected to impact. If the surfaces of the materials to be conveyed are sharp, the surface of the upper rubber layer may, in some cases, sustain cut damage.

[0003] In the past, various methods for evaluating the impact resistance of a conveyor belt have been proposed (see, for example, Patent Documents 1 to 3). Typically, the impact resistance of rubber is evaluated by understanding the damage state of a test specimen with which an impact member, such as a weight, has collided. Patent Document 4 discloses an impact testing device and a method for predicting the impact resistance of a conveyor belt top cover rubber during actual use. A contact member is repeatedly caused to collide with the surface of a rubber sample. Patent Document 5 discloses an apparatus for testing physical properties of an elastic specimen. The apparatus causes a striking end attached to a pendulum to collide with a specimen supported by a support device and measures the drop height and rebound height of the pendulum.

[0004] The impact resistance of the upper rubber covering varies depending on the rubber properties, operating environment, etc. Therefore, the appropriate rubber for the upper rubber covering must be selected taking into account the impact resistance during use of the conveyor belt. List of citationsPatent literature Patent document 1: JP 2010 - 216 852 A Patent document 2: JP 2011 - 257 187 A Patent document 3: JP 2012 - 189 533 A Patent document 4: WO 2016 / 042 999 A1 Patent document 5: JP H10 - 260 123 A Summary of the inventionTechnical problem

[0005] The object of the present invention is to provide a rubber selection method which makes it possible to select a suitable rubber which corresponds to the actual use of a target object such as a conveyor belt when selecting a rubber for the target object. Solution to the problem

[0006] To achieve the above-described object, one aspect of the present invention is a rubber selection method for selecting a rubber for use in a target object that experiences impacts from impacting objects during use; wherein, under prescribed test conditions, an impact test is conducted in which an impact member is caused to fall freely onto a sample from a plurality of rubbers having different physical properties;Data for three quantities including a loss energy absorbed by the sample when the impact element collides with the sample, a thermal energy generated at the sample, and an indentation amount in the sample by the impact element are acquired, and a specific sample is selected from the plurality of types of samples based on a ranking of the superiority of the plurality of samples with respect to the quantities for which data were acquired; wherein an optimal sample is selected from the plurality of sample types based on the ranking of superiority of the plurality of sample types with respect to each size and a priority order between each predetermined size.

[0007] Another aspect of the present invention is a rubber selection method for selecting a rubber for use in a target object to be used which, in use, will experience impact from an impacting object, wherein an impact test in which an impactor is caused to freely fall onto a sample of a plurality of rubbers having different physical properties is conducted under predetermined test conditions; data for three quantities including a dissipated energy absorbed by the sample when the impactor collides with the sample, a thermal energy generated at the sample, and an amount of indentation in the sample by the impactor are collected;a correlation between the sizes for which data were acquired and a viscoelastic property of each sample, a ranking of the superiority of the plurality of types of samples with respect to the sizes for which data were acquired, and a priority order between the respective sizes are known in advance; and when a rubber is to be selected, a specific rubber is selected from the plurality of suitable rubber types based on the viscoelastic properties of the plurality of suitable rubber types and the correlation and ranking order known in advance, wherein a rubber is selected from the plurality of suitable rubber types by placing emphasis on the ranking of the rubbers with respect to the size with the highest priority and thus selecting the rubber with the highest superiority with respect to the size with the highest priority. Advantageous effects of the invention

[0008] According to the present invention, when a plurality of rubber sample types with different physical properties are used and an impact member is made to fall freely onto the samples, data for three quantities, including a loss energy absorbed by the samples, a thermal energy generated on the samples, and an indentation amount in the samples by the impact member, are acquired and used. These items are closely related to the durability (impact resistance) of rubber. Therefore, by selecting the optimal rubber based on the ranking of the superiority of the plurality of sample types with respect to these quantities, a suitable rubber can be selected that corresponds to the actual use of the target object. Brief description of the drawings Fig. Fig. 1 is an explanatory diagram (flow chart) illustrating the procedure for selecting a suitable rubber according to the present invention. Fig. Figure 2 is an explanatory diagram illustrating the basic structure of an impact testing apparatus. Fig. Figure 3 is an explanatory diagram schematically showing a sample deformed by a free-falling impact element. Fig. Figure 4 is a graph illustrating the relationship between impact force and indentation size at room temperature. Fig. Figure 5 is a graph illustrating the relationship between impact force and indentation size at 70 °C. Fig. Figure 6 is a graph showing the change in the surface temperature of a sample over time. Fig. 7 is an explanatory diagram (flow chart) illustrating the procedure for selecting a suitable rubber according to another embodiment of the present invention. Description of embodiments

[0009] The rubber selection method of the present invention will be described below with reference to the embodiments shown in the drawings. In the present invention, a rubber is selected for use in a target object that experiences impacts from impacting objects during use. In the embodiments, a case where the target object is a conveyor belt and the rubber to be selected is used in the rubber of the top cover of the conveyor belt is described as an example.

[0010] In the present invention, a suitable sample (rubber) for use as the top cover rubber is prepared by the method described in Fig. 1, samples S of a variety of rubber types with different physical properties (e.g. viscoelastic properties) were selected.

[0011] Therefore, an impact test device 1 made of Fig. 2, an impact test is conducted in which an impact element 10 is caused to fall freely onto samples S of a variety of rubbers with different physical properties. The test conditions are preferably conditions corresponding to an environment in which the selected rubber (sample S) is actually used as the top cover rubber for a conveyor belt.

[0012] According to the present invention, when the impact member 10 and the sample S are caused to collide, data are acquired for three quantities, including a loss energy E1 absorbed by the sample S, a thermal energy E2 generated at the sample S, and an indentation amount H into the sample S by the impact member 10.

[0013] The impact testing device 1 is equipped with: a support platform 2 on which the sample S is placed; the impact element 10, which is brought into free fall onto the sample S; a load measuring device 5; a displacement measuring device 6; and a computing unit 8. The impact testing device 1 additionally has a temperature sensor 7 and a temperature controller 9.

[0014] As the impact element 10, a plurality of impact bodies 10a, 10b, 10c, 10d with different specifications such as the bottom end shape and weight are preferably provided. From this plurality of specifications, an impact element 10 is selected with a specification that closely resembles the object to be conveyed and exerts an impact on the rubber of the top cover in actual use.

[0015] In the impact testing device 1, a support section 3a is stretched between the upright frames 3, and a holding mechanism 4 is provided by this support section 3a. The support section 3a can be moved to any height position and fixed. The configuration is selected such that an impact element 10a, which is releasably held by the holding mechanism 4, can be freely dropped onto the sample S placed on the flat, plate-shaped support platform 2 by releasing the holding state.

[0016] The load measuring device 5 is installed below the support platform 2 and measures the impact force acting on the sample S. As shown in Fig. As shown in Figure 3, the displacement measuring device 6 measures the indentation amount H into the sample S by the impact element 10a, which is freely dropped and collided with the sample S. If the lower end shape of the impact element 10 is sharp, the indentation amount H becomes a flaw depth. Measurement data from the load measuring device 5 and the displacement measuring device 6 are input to the computing unit 8. Various types of computers, etc., can be used as the computing unit 8.

[0017] The temperature sensor 7 measures the surface temperature of the sample S. The surface temperature measured by the temperature sensor 7 is input to the computing unit 8. Thermography and the like can be used as the temperature sensor 7.

[0018] The temperature controller 9 adjusts the temperature of the sample S by heating or cooling the sample S to an optional temperature. In the present embodiment, the temperature controller 9 installed on the bottom of the support platform 2 heats or cools the support platform 2, thereby indirectly heating or cooling the sample S and adjusting it to an optional temperature. Additionally, a thermostat housing or the like may be used as the temperature controller 9, in which the entire tester is covered with a lid and the inside of the lid is adjusted to an optional ambient temperature.

[0019] The methods for using this impact testing apparatus 1 to acquire the data of each quantity are described below.

[0020] The sample S is placed on the Fig. 2. A suitable impact element 10a, which closely resembles the actual operating conditions of a conveyor belt 11, is selected from the plurality of impact bodies 10 and attached to the holding mechanism 4. The support section 3a is displaced, and the impact element 10 is adjusted to a suitable height position (e.g., a position of a height h from the surface of the sample S). The temperature of the sample S is adjusted to a predetermined temperature by the temperature controller 9.

[0021] Subsequently, the holding mechanism 4 deactivates the holding of the impact element 10, and the impact element 10 is allowed to fall freely and collide with the sample S. At this time, the impact energy E emitted by the impact element 10, which was freely dropped from the position of height h from the surface of the sample S, is Mgh (E = Mgh). Here, M is the already known mass of the impact element 10.

[0022] The impact force acting on the sample S is measured by the load measuring device 5 during the collision process from the moment the impact element, which has been brought into free fall, touches the sample until the impact element rebounds and detaches from the sample. The indentation circumference H in the sample S by the impact element 10, as shown in Fig. 3, is also continuously measured by the displacement measuring device 6. The impact force measured by the load measuring device 5 and the indentation circumference H measured by the displacement measuring device 6 are input into the computing unit 8. This indentation circumference H differs depending on the physical properties of the rubber.

[0023] As in Fig. 4 and Fig. As shown in Figure 5, the impact force and indentation circumference H are measured by this impact test. Fig. Figure 4 shows measurement data for a case where four types of samples S (S1 to S4) were tested at room temperature under the same test conditions (with sample S at a temperature of about 20 °C). Fig. Figure 5 shows measurement data for a case where only the temperature of the four types of samples S (S1 to S4) was changed to 70 °C and the test was performed.

[0024] The energy loss E1 absorbed by the sample S during the collision of impact element 10 and sample S is calculated by the computing unit 8 based on the input measurement data. Fig. 4 and Fig. 5, the slope area to the right of the data curves of the respective samples S shows the relationship between impact force and indentation circumference H from the contact of the impact element 10 with the sample S until the deepest indentation is reached. Therefore, the indentation energy Ea can be calculated by integrating the data curve in this area.

[0025] On the other hand, the decreasing range to the left of these data curves shows the ratio between the impact force and the indentation circumference H from the moment when the impact element 10 reaches the deepest indentation in the sample S until the impact element 10 rebounds and detaches from the sample S. Therefore, a repulsive energy Eb can be calculated by integrating the data curve in this range.

[0026] Accordingly, the energy loss E1 absorbed by the sample S can be calculated by subtracting the repulsive energy Eb from the penetration energy Ea (E1 = Ea - Eb). That is, in Fig. 4 and Fig. 5, the area enclosed by the respective data curves S1, S2, S3, S4 represents the energy loss E1 of the respective samples S. This energy loss E1 (or the (energy loss E1) / (impact energy E)) varies depending on the physical properties of the rubber.

[0027] When comparing the data of Fig. 4 and Fig. 5 shows that the energy loss E1 depends on the temperature of the sample S. Therefore, the impact test is preferably carried out in such a way that the temperature of the sample S is varied to a large number of levels in order to record the measurement data described above and to understand the temperature dependence of the energy loss E1.

[0028] With this impact test device 1, the surface temperature of the sample S can be measured immediately after the rebound of the impact element 10 with the temperature sensor 7. The surface temperature measured by the temperature sensor 7 is input into the computing unit 8. As in Fig. As shown in Figure 6, the surface temperature of the sample is measured at room temperature, and the temperature change can be tracked over time.

[0029] The thermal energy E2 generated on sample S during the collision between impact element 10 and sample S is calculated by the computing unit 8 from the measured surface temperature and the indentation circumference H. The thermal energy E2 can be calculated using E2 = mcΔT. Here, m corresponds to the mass of sample S for which the temperature has increased, c to the specific heat of sample S, and ΔT to the temperature increase of sample S.

[0030] The temperature rise ΔT (maximum temperature rise ΔT) of the sample S due to collision with the impact element 10 can be determined from the measurement data of Fig. 6. The specific heat c of sample S is determined in advance.

[0031] The mass m of the sample S whose temperature has increased is calculated, for example, as follows. The indentation circumference H by the impact element 10 is measured using the displacement measuring device 6. In addition, the shape of the impact element 10 is determined in advance, so that, for example, a volume V calculated by multiplying the maximum cross-sectional area of ​​the indented portion of the sample S when indented to the maximum depth by the impact element 10 by the maximum indentation circumference H is used as the volume V of the sample S that has increased in temperature. The specific gravity ρ of the sample S is already determined in advance, so the temperature-increased mass m of the sample S can be calculated by multiplying the volume V by the specific gravity ρ. In addition, the thermal energy E2 can be calculated by multiplying the mass m by the specific heat c and the temperature increase ΔT.This thermal energy E2 varies depending on the physical properties of rubber.

[0032] After carrying out the impact test and recording the necessary parameters, as in Fig. 1, for each of the elements for which data were collected (lost energy E1, thermal energy E and indentation circumference H), a relative evaluation of the multitude of types of specimens S on which the impact test was carried out is carried out.

[0033] The specific relative evaluation method evaluates the superiority of the plurality of samples S with respect to the sizes for which data were collected. For example, with the loss energy E1, as the loss energy E1 increases, the impact resistance is rated as superior, and thus a superiority ranking is assigned from first, second, third, and fourth place according to the largest loss energy E1. As the thermal energy E2 increases, for example, with the thermal energy E2, the impact resistance is rated as superior, and thus a superiority ranking is assigned (first place to fourth place) in order of the largest thermal energy E2. As the indentation circumference H decreases, for example, with the indentation circumference H, the defect depth becomes smaller, and thus the impact resistance is rated as superior. Therefore, a superiority ranking (first place to fourth place) is assigned starting from the smallest indentation circumference H.

[0034] Subsequently, as shown in Fig. 1, a comprehensive evaluation of each sample is performed. In this comprehensive evaluation, a specific sample S is selected from the plurality of samples S1 to S4 according to the ranking order described above. In a case where data for only one size has been recorded, the sample S with the highest superiority (first place) with respect to this size is determined, and this sample S is selected.

[0035] When data for a plurality of items has been acquired, the priority order among each preset quantity is determined in advance. For example, a ranking in the order of loss energy E1, indentation amount H, and thermal energy E2 is determined for the item with the highest priority. Furthermore, a specific optimal sample S (rubber) is selected from the plurality of sample types S1 to S4 based on the ranking of the superiority of the plurality of sample types S with respect to each item and a priority order among the respective preset items.

[0036] Specifically, in a case where a particular sample S1 exhibits the highest superiority over all elements, sample S1 is selected. However, there are also cases where a particular sample S2 exhibits the highest superiority over the quantity of loss energy E1, while other samples S1 and S3 exhibit the highest superiority over the quantity of indentation circumference H and the quantity of thermal energy E2. In such a case, the focus is placed on the ranking of samples S with respect to the quantity with the highest priority (loss energy E1), and thus sample S2 is selected.

[0037] In this way, the present invention acquires and utilizes data for the three above-described quantities closely related to the durability (impact resistance) of rubber, including the loss energy E1, the thermal energy E2, and the indentation amount H. Therefore, by selecting the optimal rubber based on the ranking of the superiority of the plurality of sample types S with respect to these quantities, a suitable rubber (top cover rubber) can be selected that corresponds to the actual use of the target object (conveyor belt).

[0038] According to the present invention, a suitable top cover rubber can be selected depending on the service life of the conveyor belt. In addition, a top cover rubber can also be selected that can suppress the defect depth within a tolerance range. By selecting based on the data of the three parameters described above, a suitable rubber (top cover rubber) that corresponds to actual use with good accuracy can be easily selected.

[0039] Next, another embodiment of the rubber selection method of the present invention will be described.

[0040] In the embodiment described above, when selecting a suitable rubber, an impact test is conducted on a plurality of samples S. However, in the present embodiment, when selecting a suitable rubber, an impact test is not conducted, and data collected by previously conducted impact tests is used.

[0041] Therefore, in the present embodiment, the three data items described in the previous embodiment, including the loss energy E1, the thermal energy E2, and the indentation amount H, are acquired, and the correlation between the data items and the viscoelastic properties of each sample S is recognized in advance. As the viscoelastic property, the loss coefficient (tanδ), the storage elastic modulus (E'), the loss elastic modulus (E"), and the like can be used.

[0042] The ranking of superiority of the plurality of samples S with respect to the sizes for which data were collected is recognized in advance. More specifically, for example, at the loss energy E1, as the loss energy E1 increases, the impact strength is judged to be superior, and thus the samples S are ranked in order of superiority, with the largest loss energy E1 being the highest. For example, as the thermal energy E2 increases, the impact strength is judged to be superior, and thus the samples S are ranked in order of superiority, with the largest thermal energy E2 being the highest. For example, at the indentation circumference H, as the defect depth decreases, the indentation circumference H decreases, and thus the impact strength is judged to be superior.

[0043] In this way, a database is created that shows the correlation with the viscoelastic property of each sample S and is stored in a computer or other computing device. Furthermore, the ranking of the superiority of the plurality of samples S with respect to each element is linked to this database. Furthermore, the data for each quantity is temperature-dependent, so it is preferable to create a database for each prescribed temperature.

[0044] Then, as in Fig. As shown in Figure 7, when selecting a suitable rubber for the top cover rubber, the viscoelastic properties of the plurality of suitable rubber types are input into the calculator. A specific rubber is selected by the calculator from the plurality of suitable rubber types based on the input viscoelastic properties and the correlation and ranking described above.

[0045] More specifically, the data for each element related to each rubber are calculated based on the previously known correlation between the viscoelastic properties of each element (loss energy E1, thermal energy E2, and indentation extent H) and the values ​​of the input viscoelastic properties. This determines the loss energy E1, thermal energy E2, and indentation extent H of each rubber.

[0046] Next, the superiority of each rubber is relatively evaluated based on the pre-known ranking for each element. This determines the order of superiority for each size.

[0047] Subsequently, the individually evaluated rubbers are comprehensively evaluated. The priority order between each element is set in advance. For example, a ranking in the order of loss energy E1, indentation range H, and thermal energy E2 is established for the element with the highest priority.

[0048] In the overall evaluation, if a particular rubber exhibits the highest superiority over all elements, that rubber is selected. However, there are also cases where a particular rubber exhibits the highest superiority in terms of energy loss E1, but another rubber exhibits the highest superiority in terms of indentation circumference H and thermal energy E2. In such a case, the focus is on ranking the rubbers according to the highest priority (energy loss E1), and thus the rubber with the highest superiority in terms of energy loss E1 is selected.

[0049] In each of the embodiments described above, cases where the target object is a conveyor belt and the rubber to be selected is used as the upper cover rubber were described as examples, but the present invention is not limited thereto. Other examples of the rubber selected by the present invention include a rubber for a lower cover for a conveyor belt, a tread rubber for a tire, and so on. List of reference symbols 1 impact test device 2 storage platforms 3 frames 3a support section 4 Holding mechanism 5 Load measuring device 6 Displacement measuring device 7 Temperature sensor 8 computing unit 9 temperature controllers 10 Impact element

[0050] Sample S (S1, S2, S3, S4)

Claims

[1] A rubber selection method for selecting a rubber for use in a target object which, in use, is subjected to impact by an impacting object, wherein an impact test in which an impact element is subjected to free fall onto a sample of a variety of rubber types with different physical properties is carried out under prescribed test conditions; Data are collected for three quantities, including a loss energy absorbed by the sample when the impact element collides with the sample, a thermal energy generated at the sample, and an indentation amount in the sample by the impact element; and a particular sample is selected from the plurality of sample types based on a ranking of the superiority of the plurality of samples with respect to the sizes for which data were collected, wherein an optimal sample is selected from the plurality of sample types based on the ranking of superiority of the plurality of sample types with respect to each size and a priority order between each predetermined size. [2] The rubber selection method according to claim 1, wherein the physical properties include at least one viscoelastic property. [3] A rubber selection method for selecting a rubber for use in a target object which, in use, experiences impact from an impacting object; wherein an impact test in which an impact element is subjected to free fall onto a sample of a variety of rubber types with different physical properties is carried out under prescribed test conditions; Data are collected for three quantities, including a loss energy absorbed by the sample when the impact element collides with the sample, a thermal energy generated at the sample, and an indentation amount in the sample by the impact element; a correlation between the quantities for which data were collected and a viscoelastic property of each sample and a ranking of the superiority of the plurality of sample types over the quantities for which data were collected, as well as a priority order between the respective quantities, are known in advance, and when a rubber is to be selected, a particular rubber is selected from the plurality of suitable rubber types on the basis of the viscoelastic properties of the plurality of rubber types and the correlation and ranking known in advance, wherein a rubber is selected from the plurality of suitable rubbers by placing emphasis on the ranking of the rubbers with respect to the size having the highest priority and thus selecting the rubber with the highest superiority with respect to the size having the highest priority. [4] The rubber selection method according to any one of claims 1 to 3, wherein the target object is a conveyor belt.

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