Review Reports - Measuring Device Detecting Impact Forces on Impact Rollers

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

I have read the paper named ‘Measuring device detecting impact forces on impact rollers’, and my first impression is that I didn’t have for a long time a better paper for initial revision. The paper is very well-structured and well-written. It contains analytic data and experiments as well, which is very good.

However, there are still minor corrections to be made:

1. Abstract to be shortened up to 200 words in accordance with the journal template.

2. The Introductory part must be concluded with a paragraph that clearly describes, where the research gap in the presented literature review is, what is new in the presented paper, and where the motivation on solving the described problem came from.

3. Before measurement description it would be good to have mechanics equations, so the reader is aware of what is measuring in the paper.

4. After the equations, the naming of variables and their units should be given.

5. In the conclusions quantify the percentage of vibration reduction, related to the other literature sources, or related to the roller state before improvements.

6. At the end of the conclusions give the directions for future research.

I have noticed that the figures are very innovative and clear, and I want to congratulate you on that.

Author Response

Dear Reviewer,

I would like to respectfully thank you for your opposing review of the article entitled " Measuring device detecting impact forces on impact rollers ". Thank you for your valuable advice and hidden opinion.

Thank you very much, Leopold Hrabovský

Question #1 - Abstract to be shortened up to 200 words in accordance with the journal template.

Answer to question #1:

I edited the abstract as follows:

This paper presents laboratory devices on which experimental measurements were carried out to prove the validity of the assumption about the reduction of vibrations transmitted to the conveyor belt structure generated by the impact forces of falling material grains in the places of transfer or on the hoppers of conveyor belts. In order to limit damage to the conveyor belts caused by the impact of the sharp edges of material grains, conveyor belts are supported by impact rollers or impact rubber rods in the places of transfers and on the hoppers of belt conveyors. The flattened ends of the impact rollers are inserted into the grooves of steel brackets installed on the supports of the fixed conveyor idlers of a conventional design. In this paper, a special modification of the fixed conveyor idler is presented, which consists of inserting plastic brackets into the structurally modified roller axle holders of the fixed conveyor idler. Measurements were carried out on the first laboratory device, which showed that the specially modified fixed conveyor idler resulted in a higher damping of up to 15% of the impact forces of the falling weight on the rubberized hoop of the impact roller shell compared to the conventional fixed conveyor idler design. Measurements carried out on the second laboratory device show that the effective vibration velocity values detected at the points where the impact roller axis fits into the fixed roller table holder, i.e. points B and D, are higher than when using plastic brackets, up to 6% for a 108 mm diameter roller, compared to steel impact roller brackets.

Question #2 - The Introductory part must be concluded with a paragraph that clearly describes, where the research gap in the presented literature review is, what is new in the presented paper, and where the motivation on solving the described problem came from.

Answer to question #2:

I inserted this text at the end of the introductory part:

The article describes the design modification of the fixed conveyor idler, the result of which is the installation of plastic brackets in the places where the flattened end parts of the conveyor roller axles are inserted into the notches created in the steel trestle of the traditional fixed conveyor idler. This modified fixed conveyor idler is characterized by two plastic brackets with notches, into which the flattened end parts of the conveyor roller axles are inserted.

The motivation to solve the described problem is this - an obligation of manufacturers or distributors of machinery, which includes belt or roller conveyors, is to introduce safe products for the market in the European Union (Czech Republic). According to Directive 2006/42/EC (Government Regulation No. 176/2008 Coll.), the manufacturer or distributor must, among other things, inform the user in the instruction manual about the noise and vibration levels caused by the machinery.

Vibration and noise arising during the transport of material are the result of several factors: connection between roller and structure-the stable connection between roller and structure reduces the possibility of vibration; material used-steel rollers produce stronger vibrations than rubber rollers, which dampen vibrations; design error-incorrect calibration of the roller rotation can cause strong vibrations, which can lead to the destruction of the roller and working environment-dusty or very humid areas can be the reason for rapid damage of bearings or roller casing.

Question #3 - Before measurement description it would be good to have mechanics equations, so the reader is aware of what is measuring in the paper.

Answer to question #3:

I added formula (3) to chapter 3.3 entitled "3.3. Vibration measurement of the rotating rubberized impact roller casing, steel roller axle bracket.”

where is: A [m] - the deflection; D_r [m] - the impact roller diameter, v(t) [m·s^-1] - the instantaneous speed value.

Question #4 – After the equations, the naming of variables and their units should be given.

Answer to question #4:

I added the explanations to equation (1) as follows:

where is: f [Hz] - the frequency (in Europe a unified distribution grid of 400/230V with a frequency of 50 Hz is used); v_r [m·s^-1] - circumferential velocity the impact roller casing; i_w [-] - the ratio of the pulley diameter D_w [m] to the drive pulley diameter d_w [m]; D_r [m] - the impact roller diameter; n_e [s^-1] - speed of the electric motor.

I added the explanations to equation (2) as follows:

where is: v_r [m·s^-1] - circumferential velocity the impact roller casing; D_r [m] - the impact roller diameter.

Question #5 - In the conclusions quantify the percentage of vibration reduction, related to the other literature sources, or related to the roller state before improvements.

Answer to question #5:

The evaluated measurements of the forces, given in Chapter “3. Results“, generated by the impact of the weight hitting the impact roller with f89 mm diameter show that (for i = 5 repeated measurements under the same technical conditions) the mean value of the measured force F_(Dr)j,i [N] at measuring point A, and also at measuring point B, (see Fig. 11(b)) is lower when the axle of the impact roller is placed in the plastic brackets.

Table 2 shows for measuring points A and B, on a fixed conveyor idler with rubber impact roller axle brackets f89 mm, the magnitude of the calculated dynamic force F_(89)A,p = 83.8 ± 1.5 N and F_(89)B,p = 85.5 ± 2.3 N.

According to Table 4, for the measuring points A and B, the dynamic force F_(89)A,s = 86.5 ± 1.4 N and F_(89)B,s = 89.0 ± 1.7 N were calculated for the fixed conveyor idler with steel impact roller axle brackets of f89 mm.

For the f89 mm impact roller, the size of the force F_(89)A,p [N] reaches 98.0% of the force F_(89)A,s [N] and the size of F_(89)B,p [N] force reaches a magnitude of 97.2% of the force F_(89)B,p [N].

At both measuring point C and measuring point D (see Fig. 11(b)) the magnitudes of the forces generated by the impact of the weight hitting the impact roller f89 mm are also lower when the axle of the impact roller is mounted in plastic brackets.

By evaluating the measurements of the forces generated by the impact of the weights hitting the impact roller f108 mm, see section “3. Results” (for i = 5 repeated measurements under the same technical conditions) it can be concluded that the mean values of the measured forces F_(Dr)j,i [N] at measuring point A, and at measuring point B, (see Fig. 11(b)) are also lower in the case of the placement of the axle of the impact roller placed in the plastic brackets.

Table 4 shows for measuring points A and B, on a fixed conveyor idler with rubber brackets for the axle of the impact roller f89 mm, the magnitude of the calculated dynamic force F_(108)A,p = 60.7 ± 10.0 N a F_(108)B,p = 62.2 ± 9.6 N.

According to Table 5, there are the calculated dynamic forces F_(108)A,s = 72.4 ± 6.5 N and F_(108)B,s = 72.9 ± 4.6 N for measuring points A and B on a fixed conveyor idler with steel brackets for the axle of this impact roller f89.

For the f108 mm impact roller the magnitude of the force F_(108)A,p [N] reaches 83.8% of the force F_(108)A,s [N] and the magnitude of the force F_(108)B,p [N] reaches 85.3% of the force F_(108)B,s [N].

The realised vibration measurements, see Chapter 3.3 and Chapter 3.4 of the rotating rubberised casing (f89 mm and f108 mm) impact roller on laboratory device, see Fig. 16, have not demonstrated, as stated in [1], [2], that the plastic brackets limit the amount of vibration (excited by the rotating casing of the conveyor roller) transferred by the support beam of a fixed conveyor idler to the steel frame of a laboratory device that simulates the conveyor belt run.

It can be seen from Table 6 and Table 10 that the vibration v_{(z)RMS(31.38)} = 1.26 mm·s^-1 (Fig. 25) in the case of mounting the impact roller axle in plastic brackets (Fig. 4(b)) is 2.8 times (by 280%) higher at measuring point B than the vibration v_{(z)RMS(31.55)} = 0.45 mm·s^-1 corresponding to mounting the impact roller axle at measuring point B in a steel bracket (Fig. 4(a)).

From Table 7 and Table 11, it can be expressed that the vibration v_{(z)RMS(31.36)} = 1.18 mm·s^-1 (Fig. 25) in the case of mounting the axle of the impact roller in plastic brackets (Fig. 4(b)) is 2.7 times (by 274%) higher at measuring point D than the vibration v_{(z)RMS(31.48)} = 0.43 mm·s^-1 corresponding to mounting the axle of the impact roller at measuring point D in a steel bracket (Fig. 4(a)).

From Table 8 and Table 12, it can be expressed that the vibration v_{(z)RMS(29.84)} = 1.14 mm·s^-1 (Fig. 26) in the case of mounting the axle of the impact roller f108 mm in plastic brackets (Fig. 4(b)) is 1.3 times (by 134%) higher than the vibration at measurement point B v_{(z)RMS(29.98)} = 0.85 mm·s^-1 for the corresponding location of the axle of the impact roller at measuring point B in the steel bracket (Fig. 4(a)).

Table 9 and Table 13 prove that the vibrations v_{(z)RMS(29.83)} = 1.13 mm·s^-1 (Fig. 26) in the case of the axle of the impact roller f108 mm placed in the plastic brackets (Fig. 4(b)) is 1.1 times (by 107%) higher at measuring point D than the vibrations v_{(z)RMS(30.00)} = 1.06 mm·s^-1 for the corresponding location of the axle of the impact roller at measuring point D in the steel bracket (Fig. 4(a)).

Question #6 – At the end of the conclusions give the directions for future research.

Answer to question #6:

I added this text to the end of the chapter "5. Conclusions":

It is intended to carry out more extensive experimental measurement analyses on this laboratory machine, the purpose of which is to obtain vibration values of conveyor rollers with steel or plastic casing, or rubberized casing, or impact rollers with different the diameters.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

1. The work presents several typographical mistakes like on line 223 it is not clear to what section refers to. Also subsection 2.1 is repeated. References to some of the tables is wrong. In my opinion authors should make a profound review of the paper.

2. Although the description of the different test is exhaustive it is presented in a very confusing manner. It is very difficult to follow which test corresponds to which case.

3. Finally it looks like that no definite conclusions are obtained from the many test performed. Thus, the work contributes very little to the understanding or improvement of the subject.

Comments on the Quality of English Language

Minor english revision required.

Author Response

Dear Reviewer,

Thank you very much, Leopold Hrabovský

Question #1 - The work presents several typographical mistakes like on line 223 it is not clear to what section refers to. Also subsection 2.1 is repeated. References to some of the tables is wrong. In my opinion authors should make a profound review of the paper.

Answer to question #1:

I removed this text: „This section may be divided by subheadings. It should provide a concise and precise description of the experimental results, their interpretation, as well as the experimental conclusions that can be drawn.“ – see section “2. Laboratory device for detecting the vibration of a rotating impact roller”.
I renamed the chapter “2.1. Impact rollers”as “2.3. Impact rollers”.
I have thoroughly checked the table numbering and figure numbering. I made a change, e.g. Table 1 na Table 2 see on line 303, Table 2 na Table 3 see on lone 317, Table 3 na Table 4 see on lone 331. Other changes are highlighted in red in the manuscript text.
I have done a thorough review of the manuscript.

Question #2 - Although the description of the different test is exhaustive it is presented in a very confusing manner. It is very difficult to follow which test corresponds to which case.

Answer to question #2:

I have added some text (in red) to the manuscript which should help increase comprehensibility.

For example:

I inserted this text at the end of the introductory part: The article describes the design modification of the fixed conveyor idler, the result of which is the installation of plastic brackets in the places where the flattened end parts of the conveyor roller axles are inserted into the notches created in the steel trestle of the traditional fixed conveyor idler. This modified fixed conveyor idler is characterized by two plastic brackets with notches, into which the flattened end parts of the conveyor roller axles are inserted.

I added formula (3) to chapter 3.3 entitled "3.3. Vibration measurement of the rotating rubberized impact roller casing, steel roller axle bracket.”

where is: A [m] - the deflection; D_r [m] - the impact roller diameter, v(t) [m·s^-1] - the instantaneous speed value.

I added the explanations to equation (1) as follows:

I added the explanations to equation (2) as follows:

where is: v_r [m·s^-1] - circumferential velocity the impact roller casing; D_r [m] - the impact roller diameter.

Question #3 - Finally it looks like that no definite conclusions are obtained from the many test performed. Thus, the work contributes very little to the understanding or improvement of the subject.

Answer to question #3:

Dear Rewiever, thank you very much for your opinion.

I would like to ask you to take into account the insufficient conclusions of the experiments carried out in the manuscript.

If you require the conclusions to be drawn up in more detail, I will add them. Please provide a more detailed specification of what needs to be completed.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Congratulations, you have answered all questions and made the requested changes. Considering to me, I would not have any further requirements.

Reviewer 2 Report

Comments and Suggestions for Authors

1. Equation (3) the source of letter type is wrong.

2. A thorough review of English is required

3. In the conclusions authors claim that “the implemented plastic brackets for the axle of the conveyor rollers in the structurally modified steel trestles of the fixed conveyor idler have the ability to dampen the vibrations excited by the rotating casing of the conveyor roller”. This statement is in contradiction with the observed at Tables 7 and 11 and also at Tables 8 and 12. Authors are required to make it clear a5t the conclusion the influence of the plastic brackets on the amplitude of vibration of the system.

Comments on the Quality of English Language

1. A thorough review of English is required

Author Response

Dear Reviewer,

I would like to respectfully thank you for your opposing review of the article entitled " Measuring device detecting impact forces on impact rollers ".

Thank you for your valuable advice and especially for your patience.

Sincerely, Leopold Hrabovský.

Question #1 - Equation (3) the source of letter type is wrong.

Answer to question #1:

I have corrected Equation (3), see line 361-362.

where is: v(t) [m·s^-1] - the instantaneous speed; A [m] - the deflection; w [rad·s^-1] - the angular speed; t [s] – the relevant time.

Question #2 - A thorough review of English is required.

Answer to question #2:

English was checked by Mgr. Gabriela Chudašová

(https://www.vsb.cz/personCards/personCard.jsp?lang=en&person=chu01)

from the Institute of Languages VSB-Technical university of Ostrava, see: https://www.vsb.cz/712/en.

Question #3 - In the conclusions authors claim that “the implemented plastic brackets for the axle of the conveyor rollers in the structurally modified steel trestles of the fixed conveyor idler have the ability to dampen the vibrations excited by the rotating casing of the conveyor roller”. This statement is in contradiction with the observed at Tables 7 and 11 and also at Tables 8 and 12. Authors are required to make it clear a5t the conclusion the influence of the plastic brackets on the amplitude of vibration of the system.

Answer to question #3:

I removed this text from the chapter "Conclusion":

The individual rubber hoops of unequal outer diameters cause oscillations and vibrations due to the unbalanced mass during the rotation of the impact rollers. The vibrations are more intense at higher impact roller speeds, as the centrifugal force of the rotating unbalanced mass is known to be proportional to the square of the angular velocity.

Experimental measurements carried out on both laboratory devices showed that the implemented plastic brackets for the axle of the conveyor rollers in the structurally modified steel trestles of the fixed conveyor idler have the ability to dampen the vibrations excited by the rotating casing of the conveyor roller. The plastic brackets fitted into the trestles of the fixed conveyor idler also allow to absorb of a part of the impact force of the falling material grains at the transfer points or on the hoppers of the conveyor belts.

I replaced (added) the following text to the chapter "conclusion" chapter:

The vibration values of the conveyor rollers (for the steel or plastic casing of the conveyor roller) [27] and also impact rollers (see Chapters 3.1 and 3.2) show that the effective values of the vibration velocity increase with the increasing speed (circumferential speed) of the conveyor roller casings. This assumption is also confirmed in article [26].

Experimental measurements carried out on the first laboratory device (see Chapter 3.1 and Chapters 3.2) showed that the implemented plastic brackets for the axle of the conveyor rollers in the structurally modified steel trestles of the fixed conveyor idler have the ability to dampen the vibrations excited by the rotating casing of the conveyor roller. The plastic brackets fitted into the trestles of the fixed conveyor idler also allow to absorb of a part of the impact force of the falling material grains at the transfer points or on the hoppers of the conveyor belts.

The realised vibration measurements of the rotating rubberised casing (f89 mm and f108 mm) impact roller on second laboratory device, see Chapter 3.3 and Chapter 3.4 have not demonstrated, as stated in [1], [2], that the plastic brackets limit the amount of vibration (excited by the rotating casing of the conveyor roller) transferred by the support beam of a fixed conveyor idler to the steel frame of a laboratory device that simulates the conveyor belt run.

This experimentally established conclusion can be explained by the fact that the individual rubber hoops of unequal outer diameters cause oscillations and vibrations due to the unbalanced mass during the rotation of the impact rollers. The vibrations are more intense at higher impact roller speeds, as the centrifugal force of the rotating unbalanced mass is known to be proportional to the square of the angular velocity.

Measurements carried out on the second laboratory device show that the effective vibration velocity values detected at the points where the impact roller axis fits into the fixed roller table holder, i.e. points B and D, are higher than when using plastic brackets, up to 6% for a 108 mm diameter roller, compared to steel impact roller brackets.

The plastic brackets embedded in the designed roller axle brackets can dampen vibrations transmitted to the conveyor belt structure. It is preferable to use these special fixed conveyor idlers along the length of the conveyor belt run, and less suitable to use them at transfer points and hoppers.