A Novel Method for the Measurement of Geometric Errors in the Linear Motion of CNC Machine Tools
, Xiaohuan Yang 1, Zekui Lv 1, Zhiming Yang 1, Haitao Zhang 2, Xinghua Li 1,* and Fengzhou Fang 3,*Round 1
Reviewer 1 Report
The authors addressed all my concerns, but they did not give more information related to my third and fourth question.
I posed the third question to support the authors' claim related to the cost-effectiveness oftheir method. If there is no comparison with other methods, the claim should be removed or toned down.
The fourth question requires a minor effort. The required information would make the results much more readable and would help the authors supporting their conclusions.
Based on these observations I suggest a further (minor) revision of the manuscript.
Author Response
We thank the reviewer for his careful read and thoughtful comments base on our manuscript and response.
The responses are as follows.
Point 1: I posed the third question to support the authors' claim related to the cost-effectiveness of their method. If there is no comparison with other methods, the claim should be removed or toned down.
Response 1: The description of cost-effectiveness has been removed for point 1 at line 63.
Point 2: The fourth question requires a minor effort. The required information would make the results much more readable and would help the authors supporting their conclusions.
Response 1: The deviation between the result measured by the laser interferometer and that by 1D artefact has been added to Figure 9, 10 and 11. Besides, the max and mean measurement deviation of position errors and angle errors has been illustrated for point 2 at line 255.
Reviewer 2 Report
The authors have been addressed correctly my suggestions. The manuscript can be accepted for publication in Applied Sciences Journal in its current form.
Author Response
Thanks a lot for your kind comments.
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
The main idea inherent in this article is not so revolutionary as the authors have claimed. However, the suggested theory for measuring the geometric errors has thoroughly been proven with various experimental evidences(ex, the laser interferometer). Overall, this article is worthy of being shown to the potential readers.
Reviewer 2 Report
The authors propose an innovative new method for Machine Tool verification, nevertheless, there are some missing points in the description that should be clarified to really understand the method.
First of all, authors should clarify what they mean by the "calibration of the reference artefact".
From a traditional point of view, the calibration of artefacts such as a bar of balls
https://www.unimetrik.es/en/products/verification-systems/barcheck/
means to measure the ball centres (in a local reference system) with an external high accuracy CMM to produce a calibration certificate. This certificate provides the nominal values to compare with during the verification of a MT.
Nevertheless, in this case, authors seem to calibrate the artefact during the measuring process because it has to be evaluated the relative position between the paraboloids and the angle sensor.
I would need a much more detailed explanation of the calibration procedure and how it is carried out. For example, if a laser interferometer is used, which lenses have to be used: position, straightness, angular?
2. According to figure 6, it is said that distance M1M2 is obtained with the laser. Therefore, it seems that a user would need to use simultaneously a laser interferometer with the angle sensor.
3. Figure 8b is confusing. It might be a question of perspective, but it seems in the picture that the laser source is behind the straightness mirror.
4. I would assume that when the artefact is vertically mounted it should be possible to measure not only the vertical straightness and the yaw error but also the X error position and the pitch error. Have you compared if the results provided by the vertically mounted artefact are consistent with the ones previously (measurement horizontally).
5. Authors do not provide information about the repeatability process. It has to be taken into account that the repeatability of CMM is not very good (they only compensate their errors when they measure, not when they move). Is the method sensible to the machine repeatability?
6. Authors should provide some insights (from a theoretical point of view) about how to get the squareness errors although the paper only evaluates one axis.
6. References 1 and 7 are the same.
7. Reference 9 and 13 are incomplete.
8. Some sentences are difficult to understand. The language has to be improved.
Reviewer 3 Report
The authors presented a novel method for assessing positioning and orientation errors of tools in CNC machines. The proposed method exploits a properly designed rig composed of several parabolic lenses and plane mirrors to estimate such errors.
The paper is well written, with a clear focus and good organization. I only have a few minor comments:
1) How many mirrors are required to cover the whole run of a CNC guide (e.g. 650mm) and what accuracy (given the possibility to calibrate the rig) is required on the alignment of the mirrors to have minor effects on the estimation of the target error?
2) The authors assume a good repeatability of the pose in its workspace. Although repeattability is better than accuracy, it is of the same order of magnitude of the accuracy. How does it affect the method?
3) Could the authors provide a short cost-benefits analysis with respect to other solutions for assurigna good positioning (e.g. linear encoders)?
4) The results are really interesting, but their presentation could be improved. For example, the overall accuracy and repeatability expressed as average +/- standard deviation could be addedd, the measurements could be repeated several times (a least with the artefact to provide information about the repeatability of the rig. I would also add a direc information of the absolute value of the difference of the LI and the artefact estimation of the error to check whether there is a trend along the direction of the guide.
5) Sintax and spelling should be revised: figures shows and not shown, "proportional" at line 86, "Especially to deserve to be mentioned" at line 109, "character" at line 186
Reviewer 4 Report
Review comments for applsci-556361:
In my opinion, this paper can be considered acceptance after major revisions according to the suggested comments.
1. It shall be better to mark a diameter of two spots as shown in Figure 7. Please comment the measurement resolutions of displacement and angle measurements depending on the spot image size.
2. Please identify the detailed dimensional sizes of the revolutionary paraboloid and plane mirror as shown in Figure 2(b).
3. If the laser interferometer is commercially available, please provide the model and production company.
4. As you mentioned in Line 234, --the rapidity, scalability and operability of the method--, how about the maximum measurement speed of the proposed method for the measured linear range of 400 mm?
5. In line 144, you mentioned that the spot image of a feature point cannot be obtained directly, so it is obtained by measuring the corresponding plane mirror. However, Equations (1)~(5) were derived according to Figure 6(b), and the feature point seems located at the central area of revolutionary paraboloid. Please explain it more consistent.
6. In Figure 3, the definitions of angles a and b shall be explained in the content.
7. Which measurement results or Figures can support the final identification position and angle errors as concluded in line 221~222. Please explain more clearly.
8. In case of Figures 9, 10 (b), the measured x-positions from 0 to 400 mm with the same distance of 50mm for each target, however, the x-positions are slightly shifted starting from 0 mm as shown in Figures 9, 10(a). Please clarify the difference.
9. The reference formats (Ref. 2, 9, 13) shall to follow the submission guideline.
