Composite material milling process stability evaluation method considering material characteristics

Abstract

The invention provides a composite material milling process stability evaluation method considering material characteristics. The composite material milling process stability evaluation method comprises the following steps: step 1, determining composite material milling parameters; 2, determining a cutting force value considering material characteristics; 3, calculating the characteristic quantity of the cutting force of the single tool in the rotation period; step 4, calculating the cutting force characteristic quantity of the multi-cutter rotation period; step 5, evaluating the stability of the milling process of the single-cutter rotation period; and step 6, evaluating the stability of the milling process of the multi-cutter rotation period. According to the method, anisotropy and heterogeneity of the composite material are considered, stability evaluation of the milling process of the composite material is carried out through combination of a single-cutter rotation period and a multi-cutter rotation period, and the accuracy of the stability evaluation method of the milling process of the composite material is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of composite material processing, and relates to stability evaluation, in particular to a composite material milling process stability evaluation method considering material characteristics. BACKGROUND

[0002] Anisotropic composite material parts are usually processed into the final shape by edge trimming, milling and drilling processes, and meet the surface quality and assembly requirements. Due to the abrasiveness of CFRP (carbon fiber reinforced composite material) itself and the processing mode of dry cutting, tool wear increases rapidly during the processing of composite material parts. The rapid growth of tool wear leads to the fact that the processing quality of parts cannot meet the requirements, including surface damage such as fiber protrusion, delamination and poor surface roughness. The unqualified surface processing quality of anisotropic composite material parts will lead to poor assembly precision and low strength of aircraft wings and other components, and even affect the performance of the aircraft.

[0003] At present, due to the anisotropy and inhomogeneity of composite materials and other characteristics, the monitoring data of the processing process presents the characteristics of multi-distribution and strong disturbance, which leads to the difficulty in extracting abnormal fluctuation characteristics and accurately identifying abnormal fluctuations in the processing process.

[0004] In view of the need for stability evaluation of the composite material milling process, a composite material milling process stability evaluation method considering material characteristics is needed to realize the quantitative evaluation of the milling process stability, so as to provide theoretical guidance for timely feedback adjustment measures and help improve the milling quality of composite materials. SUMMARY

[0005] In view of the deficiencies in the prior art, the purpose of the present application is to provide a composite material milling process stability evaluation method considering material characteristics, so as to solve the technical problem that the accuracy of the evaluation method in the prior art needs to be further improved.

[0006] In order to solve the above technical problems, the technical scheme is adopted as follows: A composite material milling process stability evaluation method considering material characteristics, which comprises the following steps: Step 1, composite material milling parameter determination: The composite material milling parameters include the milling cutter speed And the cutting force sampling frequency .

[0007] Step 2, determination of cutting force value considering material characteristics: Step 201, according to the composite material milling parameters obtained in step 1, the number of cutting force acquisition values collected in a single tool rotation period is calculated .

[0008] Step 202, based on the anisotropy and the material properties of the composite material, the material characteristics of the composite material are obtained from the axis direction, axis direction and axis direction respectively, the cutting force value in the milling process of the composite material is collected in real time, the first cutting force value in a single tool rotation cycle is represented as: ; In the formula: represents the first cutting force collection value of the axis direction collected in a single tool rotation cycle; represents the first cutting force collection value of the axis direction collected in a single tool rotation cycle; represents the first cutting force collection value of the axis direction collected in a single tool rotation cycle; represents the first cutting force collection value of the axis direction collected in a single tool rotation cycle; represents the sequence number of the cutting force collection value collected in a single tool rotation cycle, .

[0009] Step three, single tool rotation cycle cutting force characteristic quantity calculation: According to the cutting force value obtained in step two, the single tool rotation cycle cutting force characteristic quantity is calculated, and the single tool rotation cycle cutting force characteristic quantity includes the single tool rotation cycle cutting force maximum value , the single tool rotation cycle cutting force average value and the single tool rotation cycle cutting force value .

[0010] Step four, multi-tool rotation cycle cutting force characteristic quantity calculation: According to the single tool rotation cycle cutting force characteristic quantity obtained in step three, the current tool rotation cycle cutting force characteristic quantity and the three average values of the previous 19 tool current rotation cycle cutting force characteristic quantities are calculated, that is, three first average values, and the three first average values are multi-tool rotation cycle cutting force characteristic quantities.

[0011] Step five, single tool rotation cycle milling process stability evaluation: ​Step 501: Based on the single-tool rotation cycle cutting force characteristic quantity obtained in Step 3, calculate the three differences between the current tool rotation cycle cutting force characteristic quantity and the previous tool rotation cycle cutting force characteristic quantity, and record them as the three first differences. Determine whether the three first differences are greater than 2% of the corresponding current tool rotation cycle cutting force characteristic quantity. If all three first differences are less than or equal to 2%, the milling process is evaluated to be in a stable state. If one of the three first differences is greater than 2%, proceed to the evaluation process in Step 302.

[0012] Step 502: Based on the single-tool rotation cycle cutting force characteristic quantity obtained in Step 3, calculate the three average values ​​of the cutting force characteristic quantities of the previous 20 consecutive tool rotation cycles, and record them as the second average value; based on the single-tool rotation cycle cutting force characteristic quantity obtained in Step 3, calculate the three differences between the current tool rotation cycle cutting force characteristic quantity and the corresponding second average value, and record them as the three second differences; determine whether the three second differences are greater than 2% of the corresponding current tool rotation cycle cutting force characteristic quantity. If the three second differences are all less than or equal to 2%, the milling process is evaluated to be in a stable state; if one of the three second differences is greater than 2%, proceed to the stability evaluation process of the multi-tool rotation cycle milling process in Step 6.

[0013] Step 6, Stability assessment of the multi-tool rotary cycle milling process: Based on the multi-tool rotation cycle cutting force characteristic quantity obtained in step four, calculate the three differences between the multi-tool rotation cycle cutting force characteristic quantity and the second mean obtained in step five, and record them as the third difference. Determine whether the three third differences are greater than 1% of the corresponding current tool rotation cycle cutting force characteristic quantity. If the three third differences are all less than or equal to 1%, the milling process is evaluated as being in a stable state. If one of the three third differences is greater than 1%, the milling process is evaluated as being in an unstable state.

[0014] Compared with the prior art, the present invention has the following technical effects: (I) The method of the present invention takes into account the anisotropy and heterogeneity of composite materials, and evaluates the stability of composite material milling process from both single-tool rotation cycle and multi-tool rotation cycle, thereby improving the accuracy of the stability evaluation method for composite material milling process.

[0015] (II) The method of the present invention does not require additional hardware intervention, which reduces control costs and is efficient and safe. Attached Figure Description

[0016] Figure 1 The calculation results are for the single-tool rotation cycle characteristic of the composite material milling process.

[0017] Figure 2The calculation results are for the characteristic quantities of the multi-tool rotation cycle in the composite material milling process.

[0019] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0020] It should be noted that, unless otherwise specified, all materials and devices used in this invention are those known in the art.

[0021] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0022] Example: This embodiment provides a method for stability assessment of composite material milling processes considering material properties. The method includes the following steps: Step 1: Determining the milling parameters for composite materials: Composite material milling parameters include cutter speed and cutting force sampling frequency .

[0023] Step 2: Determine the cutting force value considering material properties: Step 201: Based on the composite material milling parameters obtained in Step 1, calculate the number of cutting force acquisition values ​​collected within a single tool rotation cycle. .

[0024] In step 201, the number of cutting force values ​​collected within a single tool rotation cycle. The calculation method is as follows: .

[0025] Step 202, based on the anisotropic and heterogeneous material properties of composite materials, from... Axial direction, Axial direction and The cutting force values ​​during composite material milling are acquired in real time along the axial direction, and the first value within a single tool rotation cycle is recorded. One cutting force value Represented as: ; In the formula: This represents the data collected within a single tool rotation cycle. The first in the axial direction One cutting force value was collected; This represents the data collected within a single tool rotation cycle. The first in the axial direction One cutting force value was collected; This represents the data collected within a single tool rotation cycle. The first in the axial direction One cutting force value was collected; This indicates the sequence number of the cutting force data collected within a single tool rotation cycle. .

[0026] Step 3, Calculation of the characteristic quantity of cutting force during a single tool rotation cycle: Based on the cutting force value obtained in step two, calculate the characteristic quantity of the cutting force during a single tool rotation cycle. The characteristic quantity of the cutting force during a single tool rotation cycle includes the maximum value of the cutting force during a single tool rotation cycle. Average cutting force per single tool rotation cycle and cutting force value per single tool rotation cycle .

[0027] In step three, the maximum cutting force during a single tool rotation cycle Average cutting force per single tool rotation cycle and cutting force value per single tool rotation cycle The calculation method is as follows: .

[0028] Step 4, Calculation of cutting force characteristic quantities during multi-tool rotation cycle: Based on the single-tool rotation cycle cutting force characteristic quantity obtained in step three, calculate the three averages of the current tool rotation cycle cutting force characteristic quantity and the current rotation cycle cutting force characteristic quantities of the previous 19 consecutive tools. These three averages are the three first averages, which are the multi-tool rotation cycle cutting force characteristic quantities.

[0029] In step four, the characteristic quantities of cutting force during the multi-tool rotation cycle include the maximum value of the resultant cutting force. The corresponding first mean Mean value of resultant cutting force The corresponding first mean Resultant force value of cutting force The corresponding first mean .

[0030] Step 5, Stability assessment of the single-tool rotary cycle milling process: Step 501: Based on the single-tool rotation cycle cutting force characteristic quantity obtained in Step 3, calculate the three differences between the current tool rotation cycle cutting force characteristic quantity and the previous tool rotation cycle cutting force characteristic quantity, and record them as the three first differences. Determine whether the three first differences are greater than 2% of the corresponding current tool rotation cycle cutting force characteristic quantity. If all three first differences are less than or equal to 2%, the milling process is evaluated to be in a stable state. If one of the three first differences is greater than 2%, proceed to the evaluation process in Step 302.

[0031] In step 501, the three first differences include the maximum cutting force per single tool rotation cycle. The corresponding first difference, the average cutting force per single tool rotation cycle The corresponding first difference and the cutting force value per single tool rotation cycle The corresponding first difference.

[0032] Step 502: Based on the single-tool rotation cycle cutting force characteristic quantity obtained in Step 3, calculate the three average values ​​of the cutting force characteristic quantities of the previous 20 consecutive tool rotation cycles, and record them as the second average value; based on the single-tool rotation cycle cutting force characteristic quantity obtained in Step 3, calculate the three differences between the current tool rotation cycle cutting force characteristic quantity and the corresponding second average value, and record them as the three second differences; determine whether the three second differences are greater than 2% of the corresponding current tool rotation cycle cutting force characteristic quantity. If the three second differences are all less than or equal to 2%, the milling process is evaluated to be in a stable state; if one of the three second differences is greater than 2%, proceed to the stability evaluation process of the multi-tool rotation cycle milling process in Step 6.

[0033] In step 502, the three second averages include the maximum cutting force per single tool rotation cycle. The corresponding second mean, the average cutting force per single tool rotation cycle The corresponding second average value and single-tool rotation cycle cutting force value The corresponding second mean.

[0034] In step 502, the three second differences include the maximum cutting force per single tool rotation cycle. The corresponding second difference, the average cutting force per single tool rotation cycle The corresponding second difference and the cutting force value per single tool rotation cycle The corresponding second difference.

[0035] Step 6, Stability assessment of the multi-tool rotary cycle milling process: Based on the multi-tool rotation cycle cutting force characteristic quantity obtained in step four, calculate the three differences between the multi-tool rotation cycle cutting force characteristic quantity and the second mean obtained in step five, and record them as the third difference. Determine whether the three third differences are greater than 1% of the corresponding current tool rotation cycle cutting force characteristic quantity. If the three third differences are all less than or equal to 1%, the milling process is evaluated as being in a stable state. If one of the three third differences is greater than 1%, the milling process is evaluated as being in an unstable state.

[0036] In step six, the three third differences include the maximum cutting force per single tool rotation cycle. The corresponding third difference, the average cutting force per single tool rotation cycle The corresponding third difference and the cutting force value per single tool rotation cycle The corresponding third difference.

[0037] In this embodiment, when the evaluation result in step four indicates that the milling process is in an unstable state, the milling process should be stopped. The focus should be on detecting the wear of the tool and whether chatter occurs during the milling process. In addition, it should be checked whether any accidents such as workpiece breakage have occurred, so as to adjust the milling process and improve the milling quality of composite materials.

[0038] Application example: This application example provides a stability assessment method for composite material milling processes considering material properties, based on the above embodiments. In this application example, the milling object is a unidirectional carbon fiber reinforced composite material with fibers oriented at 30°. The tool speed is 1500 rpm, the tool feed is set to 0.05 mm / rpm, and the cutting force sampling frequency is set to 51200.

[0039] The cutting force during composite material milling is collected in real time, and the characteristic quantities within a single tool rotation cycle are calculated. The calculation results are as follows: Figure 1 As shown, the stability evaluation method for the single-tool rotation cycle milling process was used to evaluate the process. The average cutting force during the forty-fifth tool rotation cycle was found to be... If the corresponding second difference is greater than 2%, that is, the change of feature point exceeds the limit, a stability assessment of the multi-tool rotation cycle milling process is performed.

[0040] The characteristic parameters were calculated for 20 consecutive tool rotation cycles, and the results are as follows: Figure 2 As shown. Using the proposed stability assessment method for multi-tool rotary cycle milling process, it was found that if all three third differences are less than or equal to 1%, the milling process is considered to be in a stable state.

[0041] The method in this application example avoids false alarms of abnormal states caused by the heterogeneity of composite materials.

Claims

1. A method for evaluating the stability of composite material milling processes considering material properties, characterized in that, The method includes the following steps: Step 1: Determining the milling parameters for composite materials: The composite material milling parameters include the milling cutter speed. and cutting force sampling frequency ; Step 2: Determine the cutting force value considering material properties: Step 201: Based on the composite material milling parameters obtained in Step 1, calculate the number of cutting force acquisition values ​​collected within a single tool rotation cycle. ; Step 202, based on the anisotropic and heterogeneous material properties of composite materials, from... Axial direction, Axial direction and The cutting force values ​​during composite material milling are acquired in real time along the axial direction, and the first value within a single tool rotation cycle is recorded. One cutting force value Represented as: ； In the formula: This represents the data collected within a single tool rotation cycle. The first in the axial direction One cutting force value was collected; This represents the data collected within a single tool rotation cycle. The first in the axial direction One cutting force value was collected; This represents the data collected within a single tool rotation cycle. The first in the axial direction One cutting force value was collected; This indicates the sequence number of the cutting force data collected within a single tool rotation cycle. ; Step 3, Calculation of the characteristic quantity of cutting force during a single tool rotation cycle: Based on the cutting force value obtained in step two, calculate the characteristic quantity of the cutting force during a single tool rotation cycle. This characteristic quantity includes the maximum value of the cutting force during the single tool rotation cycle. Average cutting force per single tool rotation cycle and cutting force value per single tool rotation cycle ; Step 4, Calculation of cutting force characteristic quantities during multi-tool rotation cycle: Based on the single-tool rotation cycle cutting force characteristic quantity obtained in step three, calculate the three average values ​​of the current tool rotation cycle cutting force characteristic quantity and the current rotation cycle cutting force characteristic quantities of the previous 19 consecutive tools. These three average values ​​are the three first average values, which are the multi-tool rotation cycle cutting force characteristic quantities. Step 5, Stability assessment of the single-tool rotary cycle milling process: Step 501: Based on the single-tool rotation cycle cutting force characteristic quantity obtained in Step 3, calculate the three differences between the current tool rotation cycle cutting force characteristic quantity and the previous tool rotation cycle cutting force characteristic quantity, and record them as the three first differences. Determine whether the three first differences are greater than 2% of the corresponding current tool rotation cycle cutting force characteristic quantity. If the three first differences are all less than or equal to 2%, the milling process is evaluated to be in a stable state. If one of the three first differences is greater than 2%, proceed to the evaluation process in Step 302. Step 502: Based on the single-tool rotation cycle cutting force characteristic quantity obtained in Step 3, calculate the three average values ​​of the cutting force characteristic quantities of the 20 consecutive tool rotation cycles before the current tool rotation cycle cutting force characteristic quantity, and record them as the second average value; based on the single-tool rotation cycle cutting force characteristic quantity obtained in Step 3, calculate the three differences between the current tool rotation cycle cutting force characteristic quantity and the corresponding second average value, and record them as the three second differences; determine whether the three second differences are greater than 2% of the corresponding current tool rotation cycle cutting force characteristic quantity; if the three second differences are all less than or equal to 2%, the milling process is evaluated to be in a stable state; if one of the three second differences is greater than 2%, proceed to the stability evaluation process of the multi-tool rotation cycle milling process in Step 6. Step 6, Stability assessment of the multi-tool rotary cycle milling process: Based on the multi-tool rotation cycle cutting force characteristic quantity obtained in step four, calculate the three differences between the multi-tool rotation cycle cutting force characteristic quantity and the second mean obtained in step five, and record them as the third difference. Determine whether the three third differences are greater than 1% of the corresponding current tool rotation cycle cutting force characteristic quantity. If the three third differences are all less than or equal to 1%, the milling process is evaluated as being in a stable state. If one of the three third differences is greater than 1%, the milling process is evaluated as being in an unstable state.

2. The method for evaluating the stability of composite material milling processes considering material properties as described in claim 1, characterized in that, In step 201, the number of cutting force values ​​collected within a single tool rotation cycle. The calculation method is as follows: 。 3. The method for evaluating the stability of composite material milling processes considering material properties as described in claim 1, characterized in that, In step three, the maximum cutting force during a single tool rotation cycle is... Average cutting force per single tool rotation cycle and cutting force value per single tool rotation cycle The calculation method is as follows: 。 4. The method for evaluating the stability of composite material milling processes considering material properties as described in claim 1, characterized in that, In step four, the characteristic quantity of the multi-tool rotation cycle cutting force includes the maximum value of the resultant cutting force. The corresponding first mean Mean value of resultant cutting force The corresponding first mean Resultant force value of cutting force The corresponding first mean .

5. The method for evaluating the stability of composite material milling processes considering material properties as described in claim 1, characterized in that, In step 501, the three first differences include the maximum value of the cutting force during a single tool rotation cycle. The corresponding first difference, the average cutting force per single tool rotation cycle The corresponding first difference and the cutting force value per single tool rotation cycle The corresponding first difference.

6. The method for evaluating the stability of composite material milling processes considering material properties as described in claim 1, characterized in that, In step 502, the three second average values ​​include the maximum cutting force per single tool rotation cycle. The corresponding second mean, the average cutting force per single tool rotation cycle The corresponding second average value and single-tool rotation cycle cutting force value The corresponding second mean.

7. The method for evaluating the stability of composite material milling processes considering material properties as described in claim 1, characterized in that, In step 502, the three second differences include the maximum cutting force per single tool rotation cycle. The corresponding second difference, the average cutting force per single tool rotation cycle The corresponding second difference and the cutting force value per single tool rotation cycle The corresponding second difference.

8. The method for evaluating the stability of composite material milling processes considering material properties as described in claim 1, characterized in that, In step six, the three third differences include the maximum cutting force per single tool rotation cycle. The corresponding third difference, the average cutting force per single tool rotation cycle The corresponding third difference and the cutting force value per single tool rotation cycle The corresponding third difference.

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