A surface integrated self-sensing turning tool system and method

Abstract

A surface integrated self-sensing turning tool system and method, the system comprising a tool bar tail, a groove, a self-sensing component, a tool head and a blade; the tool bar tail is a whole elastic square beam, the tool head is provided with a blade groove, and a fastening screw fixes the blade in the blade groove; the tool bar tail connects the tool head through a tool bar, four grooves and two mutually perpendicular square cavities are arranged at the tool bar, the grooves and the square cavities are sensing parts of the self-sensing turning tool system, and four sets of self-sensing components are fixed and integrated on four surfaces of the grooves and four surfaces of the square cavities; the self-sensing component on the surface of the groove and the self-sensing component on the surface of the square cavity closest to the former form a set of self-sensing components; the self-sensing components are parallel to the planes of the grooves and the square cavities, four planes of the grooves are parallel to four side surfaces of the tool bar, and four square cavity planes where the self-sensing components are integrated are mutually parallel to the four planes of the grooves. The application has simple structure, low manufacturing cost and high measurement precision.

Description

Technical Field

[0001] This invention belongs to the field of turning force measurement technology in turning machining, specifically relating to a surface-integrated self-sensing turning tool system and method. Background Technology

[0002] Under current technological conditions, the measurement of turning forces is mainly achieved using strain gauges or piezoelectric force gauges mounted on the cutting tool. However, due to limitations in their structure and installation methods, these two types of force gauges have the following problems: For strain gauges, the limitations of the resistance strain gauge bonding process result in low measurement accuracy and make them unsuitable for use in high-temperature environments, thus limiting their applicability. For piezoelectric force gauges, the insufficient unidirectionality of piezoelectric crystals leads to interference when measuring triaxial forces and hysteresis when measuring static forces, resulting in low measurement accuracy. Both strain gauges and piezoelectric force gauges are relatively large, further limiting their applicability.

[0003] Existing self-sensing cutting tools are not only structurally complex, but their measurement accuracy is also primarily improved by addressing the tool structure and the precision of the self-sensing components, with limited research on optimizing decoupling algorithms. However, decoupling algorithms have a significant impact on the accuracy of self-sensing systems.

[0004] Existing decoupling algorithms simply assume the force-bearing position of the tool is a point on the entire cross-section of the tool holder or its central axis, without considering the influence of the tool tip position, other tool geometric parameters, and tool cutting parameters on the voltage output of the self-sensing component. Therefore, existing decoupling algorithms significantly negatively impact the accuracy of the self-sensing of cutting forces.

[0005] Therefore, it is necessary to invent a cutting force self-sensing turning tool system and its decoupling algorithm to solve the problems of complex structure and low measurement accuracy of existing turning force measurement technology. Summary of the Invention

[0006] In order to overcome the problems existing in the prior art, the purpose of this invention is to provide a surface-integrated self-sensing turning tool system and method, which is not only simple in structure and low in manufacturing cost, but also has high measurement accuracy.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A surface-integrated self-sensing turning tool system, the system includes a tool holder tail 10, a groove 7, a self-sensing component, a tool head 3 and a cutting tool 1;

[0009] The tail section 10 of the cutter bar is an elastic square beam, and the cutter head 3 is provided with a blade groove. The fastening screw 2 fixes the blade 1 in the blade groove.

[0010] The tail of the tool holder 10 is connected to the head of the tool 3 through the tool holder. Four grooves 7 and two mutually perpendicular square cavities are provided at the tool holder. The grooves 7 and square cavities are the sensing parts of the cutting force self-sensing turning tool system. Four sets of self-sensing components are fixedly integrated on the four surfaces of the grooves 7 and the four surfaces of the square cavities. The self-sensing components on the surface of the grooves 7 and the self-sensing components on the surface of the nearest square cavity form a set of self-sensing components.

[0011] The self-sensing component is parallel to the groove 7 and the square cavity plane. The four planes of the groove 7 are parallel to the four sides of the tool holder. The four square cavity planes of the integrated self-sensing component are parallel to each other on the four planes of the groove 7.

[0012] The substrate length and width of the self-sensing component are equal to the plane length and width of the square cavity integration point. The self-sensing component integrated on the surface of the groove 7 is parallel to its corresponding square cavity surface self-sensing component and coincides in the other two directions.

[0013] The voltage signal output by the self-sensing component is first amplified by a signal amplifier, then acquired by a data acquisition card and transmitted to a computer system. The computer uses software such as LabVIEW to build a data conversion platform based on a decoupling algorithm to convert the voltage signal into a three-dimensional cutting force signal.

[0014] The four sets of self-sensing components have the same structural performance parameters, each including two elastic substrates and four resistance strain gauges. A full-bridge DC circuit is selected as the measurement circuit for the strain gauges. The bridge includes four purely resistive arms, U0 is the power supply voltage, and U is the output voltage. R1, R2, R3, and R4 are all resistance strain gauges, which change with the strain of the tool holder. When the self-sensing component experiences strain, causing changes in resistance ΔR1, ΔR2, ΔR3, and ΔR4 (R1→R1+ΔR1, R2→R2-ΔR, R3→R3-ΔR, R4→R4+ΔR4), the balance of the bridge is disrupted, generating a voltage. The general form of the bridge output voltage is:

[0015]

[0016] Four resistance strain gauges are connected in series. R1 is adjacent to R2 and R3, R1 is opposite to R4, and R2 is opposite to R3.

[0017] The two elastic substrates of each self-sensing component are respectively installed on the surface of the square cavity and the surface of the groove 7 closest to it. The first group of sensing components 15 and the second group of self-sensing components 16 form the first output unit, the third group of sensing components 12 and the fourth group of self-sensing components 13 form the second output unit, the fifth group of sensing components 5 and the sixth group of self-sensing components 6 form the third output unit, and the seventh group of sensing components 8 and the eighth group of self-sensing components 9 form the fourth output unit.

[0018] Under the action of the main cutting force, output units 1 and 3 will output voltages of equal magnitude but opposite polarity. Under the action of the feed force, output units 2 and 4 will output voltages of equal magnitude but opposite polarity. Under the action of the cutting resistance, all four output units will output voltages of equal magnitude and the same polarity. Through the corresponding decoupling algorithm, the voltage signals output by the output units can be converted into three-dimensional force signals.

[0019] The decoupling algorithm accurately converts the four voltage signals output by the sensing system under various cutting conditions of the turning tool into real-time cutting force signals.

[0020] An operation method for a surface-integrated self-sensing turning tool system.

[0021] The full-bridge circuit not only boasts high self-sensing sensitivity but also eliminates nonlinear errors and compensates for temperature errors. If the self-sensing accuracy requirement for the cutting force self-sensing turning tool system is not high, it is unnecessary to consider the errors caused by geometric parameters such as tool tip position and cutting parameters on the self-sensing results. This includes the following steps:

[0022]

[0023] Among them, F c F f F p These represent the main cutting force, feed force, and depth of cut resistance, respectively. U1, U2, U3, and U4 are the output voltages of the four sets of self-sensing components, respectively. K X K Y K Z These refer to the sensitivity of the self-sensing component in three directions: feed force, cutting resistance, and main cutting force.

[0024] K X K Y K Z It can be obtained by the following formula:

[0025]

[0026]

[0027]

[0028] In the formula, U0 is the input voltage of the self-sensing component, K0 is the sensitivity coefficient of a single resistance wire in the self-sensing component, l is the total length of the resistance wire, L is the total length of the tool bar, A′ is the cross-sectional area of ​​the tool bar groove 7, A1′ is the cross-sectional area of ​​the tool bar near the first square cavity 4 of the tool head 3, A2′ is the cross-sectional area of ​​the tool bar away from the second square cavity 14 of the tool head 3, a′ is the X-direction side length (width in the X-direction) of the tool bar groove 7, and b′ is the Z-direction thickness (width in the Z-direction) of the tool bar groove 7. y1 is the distance from the tail end of the tool holder groove 7 to the tail clamping point, y2 is the distance from the tail end of the tool holder groove 7 to the tail clamping point, y3 is the distance from the tail end of the tool holder first square cavity 4 to the tail clamping point, and y4 is the distance from the tail end of the tool holder second square cavity 14 to the tail clamping point.

[0029] If the self-sensing accuracy requirement of the self-sensing turning tool system for cutting force is high, the error caused by the tool tip position to the self-sensing result needs to be considered. The corresponding decoupling algorithm is as follows:

[0030]

[0031] In the formula, c and d are the distances from the tool tip to the central axis of the tool holder in the directions of the main cutting force and the feed force, respectively.

[0032] If the self-sensing accuracy requirement of the self-sensing turning tool system is very high, it is necessary to consider not only the error caused by the tool tip position to the self-sensing result, but also the error caused by the tool geometry parameters and cutting parameters. The corresponding decoupling algorithm is as follows:

[0033]

[0034] c, d′, and L′ can be obtained from the following formula:

[0035]

[0036]

[0037]

[0038]

[0039] In the formula, a p γ0 and γ0 are the depth of cut and the tool rake angle, respectively;

[0040] The higher the accuracy of a signal decoupling algorithm, the higher its complexity. Users should select the appropriate signal decoupling algorithm based on the accuracy requirements of their actual work process.

[0041] The beneficial effects of this invention are:

[0042] The system structure of the present invention is simple. It only requires a groove 7 to be provided on the part of the tool holder near the tool head 3, and the self-sensing component to be integrated on the surface of the groove 7.

[0043] For different accuracy requirements, when the self-sensing accuracy requirement is low, the method of this invention can be adopted without considering the tool tip position and other tool geometric parameters and cutting parameters. This algorithm is simple and easy to calculate. When the self-sensing accuracy requirement is high, a method that considers the tool tip position is used. This method is more difficult to calculate than the former, but the accuracy can be significantly improved. When the self-sensing accuracy requirement is extremely high, a method that considers the tool tip position and other tool geometric parameters and cutting parameters is used. This method is more difficult to calculate than the former two, but the accuracy is extremely high. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the cutting force self-sensing turning tool system of the present invention.

[0045] Figure 2 The three-view diagram is for output unit number one.

[0046] Figure 3 The three-view diagram is for output unit number three.

[0047] Figure 4 The three-view diagram is for output unit number two.

[0048] Figure 5 The three-view diagram is for output unit number four.

[0049] Figure 6 This is the circuit connection diagram for the first output unit bridge.

[0050] Figure 7 This is the circuit connection diagram for the third output unit bridge.

[0051] Figure 8 This is the circuit connection diagram for the second output unit bridge.

[0052] Figure 9 This is the circuit connection diagram for output unit number four.

[0053] Figure 10 This is a schematic diagram illustrating the process of the force being equivalently transferred from the tool tip to the axis of the tool holder.

[0054] Figure 11 This is a schematic diagram of the cutting geometry of the tool.

[0055] Figure 12 These are the front and top views of a 3D cutting force self-sensing tool.

[0056] In the diagram: 1-Blade; 2-Fasting screw; 3-Blade head; 4-First square cavity; 5-Sensing component No. 5; 6-Sensing component No. 6; 7-Groove; 8-Sensing component No. 7; 9-Sensing component No. 8; 10-Tail end of the blade; 11-Wire hole; 12-Sensing component No. 3; 13-Sensing component No. 4; 14-Second square cavity; 15-Self-sensing component No. 1; 16-Sensing component No. 2; 1501-First elastic substrate; 1502-Strain gauge No. 1 of self-sensing component No. 1; 1503-Strain gauge No. 4 of self-sensing component No. 1; 1601-Second elastic substrate; 1602-Strain gauge No. 2 of self-sensing component No. 1; 1603-Strain gauge No. 3 of self-sensing component No. 1; 501-Third elastic substrate; 502-Strain gauge No. 2 of self-sensing component No. 2 ; 503 - Strain gauge No. 4 of self-sensing component No. 3; 601 - Fourth elastic substrate; 602 - Strain gauge No. 1 of self-sensing component No. 2; 603 - Strain gauge No. 4 of self-sensing component No. 2; 1201 - Fifth elastic substrate; 1202 - Strain gauge No. 1 of self-sensing component No. 3; 1203 - Strain gauge No. 4 of self-sensing component No. 3; 1301 - Sixth elastic substrate; 1302 - Strain gauge No. 2 of self-sensing component No. 3; 1303 - Strain gauge No. 3 of self-sensing component No. 3; 801 - Seventh elastic substrate; 802 - Strain gauge No. 2 of self-sensing component No. 4; 803 - Strain gauge No. 4 of self-sensing component No. 4; 901 - Eighth elastic substrate; 902 - Strain gauge No. 1 of self-sensing component No. 4; 903 - Strain gauge No. 4 of self-sensing component No. 4. Detailed Implementation

[0057] The present invention will now be described in further detail with reference to the accompanying drawings.

[0058] Example 1

[0059] like Figure 1-12 The diagram illustrates a self-sensing cutting force turning tool system and its decoupling algorithm. The system includes a tool shank tail section 10, a groove 7, a square cavity, self-sensing components, a tool head 3, and inserts 1. The tool shank is an elastic square beam. The tool head 3 has insert grooves, and fastening screws 2 fix the inserts 1 in these grooves. The groove 7 and two square cavities are located near the tool head 3. These grooves and cavities are the sensing components of the self-sensing cutting force turning tool system. Four sets of self-sensing components are fixedly integrated on the four surfaces of the groove 7 and the four surfaces of the square cavities. The decoupling algorithm accurately converts the four voltage signals output by the sensing system under various cutting conditions into real-time cutting force signals.

[0060] The four sets of self-sensing components have identical structural performance parameters, each including two elastic substrates and four resistance strain gauges. A full-bridge DC circuit is selected as the measurement circuit for the strain gauges. The structure of the DC bridge circuit is as follows: Figure 6-9As shown. The bridge consists of four purely resistive arms, where U0 is the power supply voltage and U is the output voltage.

[0061] R1, R2, R3, and R4 are all resistance strain gauges, which change with the strain of the tool holder. When the self-sensing component is subjected to three-dimensional force and undergoes strain, it will cause changes in resistance value ΔR1, ΔR2, ΔR3, ΔR4 (R1→R1+ΔR1, R2→R2-ΔR, R3→R3-ΔR, R4→R4+ΔR4). At this time, the balance of the bridge is disrupted, and a voltage output is generated.

[0062] If the precision requirement is not high during the cutting process, the influence of the tool tip position on the output of the sensing component does not need to be considered, or if the tool tip is located at a point on the central axis of the tool holder, a decoupling algorithm that does not consider the influence of the tool tip position on the self-sensing result can be used to decouple the sensing signal.

[0063] If high precision is required during the cutting process and the tool tip position is not collinear with the tool holder's central axis, then the influence of the tool tip position on the output of the sensing component needs to be considered. In this case, the force result of the tool tip needs to be equivalently transformed to the tool holder's central axis. At this time, a decoupling algorithm that considers the effect of the tool tip position on the self-sensing result needs to be used to decouple the sensing signal.

[0064] If the precision requirements are extremely high during the cutting process and the tool tip position is not collinear with the tool holder's central axis, then the influence of the tool tip position, other tool geometric parameters, and cutting parameters on the output results of the sensing component needs to be considered. In this case, the force result of the midpoint of the main cutting edge participating in the cutting part needs to be equivalently transformed to the tool holder's central axis. At this time, a decoupling algorithm that considers the impact of the tool tip position, other geometric parameters, and cutting parameters on the self-sensing results needs to be used to decouple the sensing signal.

[0065] like Figure 2 As shown: Output unit number one consists of self-sensing component number one 15 and self-sensing component number two 16, including two elastic substrates 1501 and 1601 and four resistance strain gauges 1502, 1503 and 1602 and 1603. Under the influence of the main cutting force, strain gauges 1502 and 1503 are stretched, thus increasing their resistance; strain gauges 1602 and 1603 are compressed, thus decreasing their resistance. Figure 6As shown: The circuit connection of output unit 1 is 1502-1602-1503-1603-1502, meaning strain gauges 1502 and 1602 are connected in series, and 1503 and 1603 are connected in series, then connected in parallel to the circuit with input U0. Strain gauges 1502 and 1503 are not adjacent, nor are strain gauges 1602 and 1603. The increase in resistance of strain gauges 1502 and 1503 and the decrease in resistance of strain gauges 1602 and 1603 cause the output voltage U1 to change from 0 to a positive value. Under the action of cutting force, the resistance of all strain gauges decreases. Since the sensitivity coefficients of strain gauges 1502 and 1503 are greater than those of strain gauges 1602 and 1603, this also causes the output voltage U1 to change from 0 to a negative value. The feed force does not affect the output voltage U1.

[0066] like Figure 3 As shown: Output unit number three consists of self-sensing components number five and six, including two elastic substrates 501 and 601 and four resistance strain gauges 502, 503 and 602, 603. Under the influence of the main cutting force, strain gauges 502 and 503 are compressed, thus decreasing their resistance; strain gauges 602 and 603 are stretched, thus increasing their resistance. Figure 7 As shown, the circuit connection of output unit number three is 602-502-603-503-602, meaning strain gauges 502 and 602 are connected in series, and 503 and 603 are connected in series, then connected in parallel to the circuit with input U0. Strain gauges 502 and 503 are not adjacent, nor are strain gauges 602 and 603. The decrease in resistance of strain gauges 502 and 503 and the increase in resistance of strain gauges 602 and 603 cause the output voltage U3 to change from 0 to negative. Under the action of cutting force, the resistance of all strain gauges decreases. Since the sensitivity coefficients of strain gauges 502 and 503 are smaller than those of strain gauges 602 and 603, this also causes the output voltage U3 to change from 0 to negative. The feed force does not affect the output voltage U3.

[0067] like Figure 4 As shown: Output unit number two consists of self-sensing component number three 12 and self-sensing component number four 13, including two elastic substrates 1201 and 1301 and four resistance strain gauges 1202, 1203 and 1302 and 1303. Under the influence of the feed force, strain gauges 1202 and 1203 are stretched, thus increasing their resistance; strain gauges 1302 and 1303 are compressed, thus decreasing their resistance. Figure 8As shown, the circuit connection of output unit 2 is 1202-1302-1203-1303-1202, meaning strain gauges 1202 and 1303 are connected in series, then in parallel to the circuit with input U0. Strain gauges 1202 and 1203 are not adjacent to each other, nor are strain gauges 1302 and 1303 adjacent to each other. The increase in resistance of strain gauges 1202 and 1203 and the decrease in resistance of strain gauges 1302 and 1303 cause the output voltage U2 to change from 0 to a positive value. Under the action of cutting force, the resistance of the strain gauges decreases. Since the sensitivity coefficients of strain gauges 1202 and 1203 are greater than those of strain gauges 1302 and 1303, this also causes the output voltage U2 to change from 0 to a negative value. The main cutting force does not affect the output voltage U2.

[0068] like Figure 5 As shown: Output unit number four consists of self-sensing component number seven (8) and self-sensing component number eight (9), including two elastic substrates 801 and 901 and four resistance strain gauges 802, 803 and 902, 903. Under the influence of the feed force, strain gauges 802 and 803 are compressed, thus decreasing their resistance; strain gauges 902 and 903 are stretched, thus increasing their resistance. Figure 9 As shown, the circuit connection of output unit 1 is 802-902-803-903-802, meaning strain gauges 802 and 902 are connected in series, and 803 and 903 are connected in series, then connected in parallel to the circuit with input U0. Strain gauges 802 and 803 are not adjacent, nor are strain gauges 902 and 903. The decrease in resistance of strain gauges 802 and 803 and the increase in resistance of strain gauges 902 and 903 cause the output voltage U4 to change from 0 to negative. Under the action of cutting force, the resistance of all strain gauges decreases. Since the sensitivity coefficients of strain gauges 802 and 803 are smaller than those of strain gauges 902 and 903, this also causes the output voltage U4 to change from 0 to negative. The main cutting force does not affect the output voltage U4.

[0069] Under the sole action of the main cutting force, U1 and U3 are equal in magnitude but opposite in sign; under the sole action of the feed force, U2 and U4 are equal in magnitude but opposite in sign. However, during actual operation, the tool is simultaneously subjected to the main cutting force, feed force, and cutting resistance, and these forces in three directions are coupled together. Therefore, the three-dimensional cutting force cannot be directly calibrated using the output voltage of the self-sensing component acquired by the data acquisition card; signal decoupling is required before calibrating the cutting force.

[0070] like Figure 10 The diagram shows the process of the tool's force position being transformed from the equivalent position to the tool holder spindle position. It is also a schematic diagram of the decoupling algorithm optimization considering the tool tip position.

[0071] like Figure 11The diagram shows a schematic of the geometric position of the cutting tool during the cutting process, and also a schematic diagram of the decoupling algorithm optimization principle considering geometric parameters and cutting parameters.

[0072] Decoupling principle:

[0073]

[0074] Solving for the given information, we get:

[0075]

Claims

1. A surface-integrated self-sensing turning tool system, characterized in that, The system includes a tool holder tail (10), a groove (7), a self-sensing component, a tool head (3), and a blade (1); The tail of the cutter bar (10) is an elastic square beam, and the cutter head (3) is provided with a blade groove. The fastening screw (2) fixes the blade (1) in the blade groove. The tail of the tool holder (10) is connected to the tool head (3) through the tool holder. Four grooves (7) and two mutually perpendicular square cavities are provided at the tool holder. The grooves (7) and square cavities are the sensing parts of the cutting force self-sensing turning tool system. Four sets of self-sensing components are fixedly integrated on the four surfaces of the grooves (7) and the four surfaces of the square cavities. The self-sensing components on the surface of the grooves (7) and the self-sensing components on the surface of the nearest square cavity form a set of self-sensing components. The self-sensing component is parallel to the groove (7) and the square cavity plane. The four planes of the groove (7) are parallel to the four sides of the tool holder. The four square cavity planes of the integrated self-sensing component are parallel to the four planes of the groove (7) respectively. The four sets of self-sensing components have identical structural performance parameters, each including two elastic substrates and four resistance strain gauges. A full-bridge DC circuit is selected as the measurement circuit for the strain gauges. The bridge consists of four purely resistive arms, U0 is the power supply voltage, and U is the output voltage. R1, R2, R3, and R4 are the resistance values ​​of the resistance strain gauges, which change with the strain of the tool holder. When the self-sensing component experiences strain, causing changes in resistance values ​​ΔR1, ΔR2, ΔR3, and ΔR4, the resistance values ​​are: R1→R1+ΔR1, R2→R2-ΔR2, R3→R3-ΔR3, and R4→R 4+ ΔR4 disrupts the balance of the bridge circuit, generating a voltage. The general form of the bridge output voltage is: Four resistance strain gauges are connected in series, with R1, R2, and R3 adjacent to each other, R1 and R4 opposite each other, and R2 and R3 opposite each other; The two elastic substrates of each self-sensing component are respectively installed on the surface of the square cavity and the surface of the groove (7) closest to it. The first self-sensing component (15) and the second self-sensing component (16) form the first output unit, the third self-sensing component (12) and the fourth self-sensing component (13) form the second output unit, the fifth self-sensing component (5) and the sixth self-sensing component (6) form the third output unit, and the seventh self-sensing component (8) and the eighth self-sensing component (9) form the fourth output unit. Under the action of the main cutting force, output units 1 and 3 will output voltages of equal magnitude but opposite polarity. Under the action of the feed force, output units 2 and 4 will output voltages of equal magnitude but opposite polarity. Under the action of the cutting resistance, all four output units will output voltages of equal magnitude and the same polarity. Through the corresponding decoupling algorithm, the voltage signals output by the output units can be converted into three-dimensional force signals. The decoupling algorithm accurately converts the four voltage signals output by the sensing system under various cutting conditions of the turning tool into real-time cutting force signals.

2. The surface-integrated self-sensing turning tool system according to claim 1, characterized in that, The substrate length and width of the self-sensing component are equal to the plane length and width of the square cavity integration point. The self-sensing component integrated on the surface of the groove (7) is parallel to its corresponding square cavity surface self-sensing component and coincides in the other two directions.

3. The surface-integrated self-sensing turning tool system according to claim 1, characterized in that, The voltage signal output by the self-sensing component is first amplified by a signal amplifier, then acquired by a data acquisition card and transmitted to a computer system. The computer uses a decoupling algorithm and LabVIEW software to build a data conversion platform to convert the voltage signal into a three-dimensional cutting force signal.

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