A compound intelligent detection method and a cutting device

Abstract

The present invention relates to a compound intelligent detection method and a cutting device. The steps of the method are as follows: S1, detecting the cutting force of the tool tip; S2, detecting the acceleration; S3, calculating the inertial force; S4, calculating the actual cutting force; S5, calculating the tool feed rate. The device includes an annular base, a tool tip assembly and an annular piezoelectric actuator. The tool tip assembly includes a flexible hinge, an acceleration sensor, a force sensor and a tool tip. The force sensor detects the cutting force of the tool tip, and the acceleration sensor detects the acceleration to obtain the inertial force of the tool tip, so as to accurately calculate the actual cutting force and the tool feed rate. The cutting force F of the tool tip is obtained in real time through the force sensor, the inertial force F2 is detected and calculated in real time through the acceleration sensor, the actual cutting force F is calculated in real time through F - F2, and the tool feed rate is calculated in real time by integrating the acceleration. The advantages of using the acceleration sensor are high precision, simple structure and low price, which reduce the assembly difficulty and cost of the device.

Description

Technical Field

[0001] The present invention relates to the technical field of machining, and in particular to a composite intelligent detection method and a cutting device for a fast tool servo technology. Background Art

[0002] When a product is being processed, various machining technologies are required to facilitate its shaping into the required finished product. The fast tool servo mechanism uses high-frequency cutting and is the one with the highest cutting efficiency and cutting accuracy in the machining technology field. Currently, most fast tool servo technologies only use a displacement sensor to feedback the cutting amount and cannot feedback the cutting force. After the tool tip wears, the cutting accuracy will decrease. In response to this situation, Japanese scholars made improvements, that is, adding a force sensor to the tool tip to measure the cutting force and feedback it, which can detect the tool tip wear. However, in the improved fast tool servo technology, the force directly detected by the force sensor for cutting feedback includes the component of the mechanism inertial force. Affected by the mechanism inertial force, the magnitude of the actual cutting force cannot be feedback, so the accuracy of the fast tool servo technology can still be improved.

[0003] In Japanese Patent JP4528937B2, the force sensor is placed at the end of the cutting device. The detected cutting force F measured includes the actual cutting force F1 and the inertial force F2. Since the force sensor is located at the end of the cutting device, the inertial force F2 is relatively large, and the tool tip cutting force is greatly affected by the inertial force, resulting in that the tool tip cutting force F cannot accurately reflect the value of the actual cutting force F1.

[0004] In the cutting device disclosed in Chinese Patent CN101456142A, the force sensor is placed close to the tool tip. Although the influence of the inertial force F2 on the reading of the force sensor is reduced, since the value of the inertial force F2 cannot be detected, the influence of the inertial force F2 still cannot be eliminated, and the accurate value of the actual cutting force F1 cannot be obtained.

[0005] The above two methods estimate the actual cutting force by using a look-up table method based on parameters such as the vibration frequency, vibration displacement, and mass of the tool tip position in combination with the reading of the force sensor, and cannot accurately feedback and also cannot online and real-time feedback the actual cutting force; at the same time, the existing fast tool servo technology uses a displacement sensor to feedback the cutting amount. The installation of the displacement sensor requires a high-precision fixture and complex debugging. In the case of a tool feed of micron level, the machining accuracy requirements for the relevant mating parts for clamping the displacement sensor are very high, resulting in high processing costs, and the initial installation position of the displacement sensor needs to be calibrated, and the calibration difficulty is relatively large. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a compound intelligent detection method and a cutting device for fast tool servo technology, which can remove the influence of inertial force through calculation, realize real-time online feedback of the actual cutting force, and at the same time use an acceleration sensor to measure the tool feed amount, eliminating the need for high-precision calibration.

[0007] The technical solution adopted by the present invention to solve its technical problem is: a compound intelligent detection method for detecting the cutting force and the tool cutting feed amount of a fast tool servo cutting device. The steps of this method are as follows:

[0008] S1. Detect the cutting force of the tool head, which is directly obtained through a force sensor inside the cutting device;

[0009] S2. Detect the acceleration, and obtain the acceleration through an acceleration sensor arranged inside the cutting device;

[0010] S3. Calculate the inertial force, obtain the moving mass on the force sensor, and calculate the inertial force through formula 1.

[0011] F2 = M × a Formula 1;

[0012] Wherein, F2 is the inertial force, M is the moving mass, and a is the acceleration;

[0013] S4. Calculate the actual cutting force, which is calculated through formula 2.

[0014] F1 = F - F2 Formula 2;

[0015] Wherein, F is the cutting force of the tool head, F1 is the actual cutting force, and F2 is the inertial force;

[0016] S5. Calculate the tool feed amount, and obtain the tool feed amount through integral operation of the acceleration.

[0017] More specifically, the moving mass is the sum of the masses of the objects directly and indirectly acting on the force sensor and arranged between the force sensor and the object to be cut.

[0018] A cutting device based on the above method includes an annular base, a tool head assembly arranged at one end of the annular base, and an annular piezoelectric actuator fixed inside the annular base and abutting against the tool head assembly. The tool head assembly includes a flexible hinge fixed at the end of the annular base, an acceleration sensor fixed on the flexible hinge, a force sensor fixed on the flexible hinge, and a tool head arranged on the force sensor. The annular piezoelectric actuator abuts against the flexible hinge. The force sensor detects the force borne by the tool head and gives feedback. The acceleration sensor detects the acceleration on the flexible hinge and gives feedback to obtain the inertial force, the actual cutting force, and the tool feed amount.

[0019] More specifically, the flexible hinge is circular and includes a fixed part located on the circumference, a working part in the middle, and an elastic part connecting the fixed part and the working part. The fixed part is fixedly connected to the annular base. The force sensor, the tool bit, and the acceleration sensor are fixed on the working part, and the annular piezoelectric actuator abuts against the working part.

[0020] More specifically, a cover plate is arranged between the tool bit and the force sensor. The tool bit is fixed on the cover plate, and the cover plate is fixed on the working part of the flexible hinge through screws passing through the cover plate and the force sensor.

[0021] More specifically, a first positioning groove is formed on the end face of the working part close to the force sensor, and a second positioning groove is formed on the end face of the cover plate close to the force sensor. The first positioning groove and the second positioning groove are opposite to each other, and the force sensor is arranged in the first positioning groove and the second positioning groove.

[0022] More specifically, the cover plate includes a top plate for fixing the tool bit and baffles extending from both sides of the top plate to the flexible hinge. The baffles cover the working part. An annular groove is arranged at the end of the baffle, and a sealing ring is placed in the annular groove.

[0023] More specifically, a third positioning groove is formed on the end face of the working part far from the force sensor, and the end of the annular piezoelectric actuator is clamped in the third positioning groove.

[0024] More specifically, the acceleration sensor is arranged on the end face of the flexible hinge far from the force sensor and is located at the central position of the flexible hinge.

[0025] The beneficial effects of the present invention are as follows: The cutting force F of the tool bit is obtained by real-time detection of the force sensor, the inertial force F2 is obtained by real-time detection and calculation of the acceleration sensor, the actual cutting force F is obtained by real-time calculation of F - F2, and at the same time, the tool feed amount can be obtained by integrating the acceleration detected by the acceleration sensor in real time. The advantage of using the acceleration sensor is that it has high precision, simple structure, and relatively low price. On the premise of ensuring the detection accuracy, the assembly difficulty and cost of the device can be reduced. Description of the Drawings

[0026] Figure 1 is a flowchart of the detection method of the present invention;

[0027] Figure 2 is a schematic structural diagram of the cutting device of the present invention;

[0028] Figure 3 is a schematic structural diagram of the flexible hinge of the present invention;

[0029] Figure 4It is a schematic structural diagram of the cover plate of the present invention.

[0030] In the figure: 1. Acceleration sensor; 2. Annular piezoelectric actuator; 3. Flexible hinge; 4. Force sensor; 5. Cover plate; 6. Tool tip; 7. Annular base; 31. Fixed plate; 32. Working part; 33. Elastic part; 34. First positioning groove; 35. Third positioning groove; 51. Top plate; 52. Baffle; 53. Second positioning groove; 54. Annular groove. Detailed implementation mode

[0031] The present invention will be described in detail below with reference to the accompanying drawings.

[0032] As Figure 1 And Figure 2 As shown, a compound intelligent detection method is used to detect the cutting force and tool cutting feed of a quick tool servo cutting device. The steps of this method are as follows.

[0033] S1. Detect the cutting force of the tool tip, which is directly obtained through the force sensor 4 inside the cutting device. The force sensor 4 is installed inside the cutting device, and the installation position requires the force sensor 4 to be able to receive the reaction force transmitted from the tool tip 6. The detected reaction force is the cutting force F of the tool tip, and the obtained cutting force F of the tool tip is obtained by adding the actual cutting force F1 and the inertial force F2. Therefore, to obtain the actual cutting force F1, the inertial force F2 needs to be obtained.

[0034] S2. Detect the acceleration, and obtain the acceleration through the acceleration sensor 1 provided inside the cutting device.

[0035] S3. Calculate the inertial force, obtain the moving mass on the force sensor 4, and calculate the inertial force F2 through formula 1.

[0036] F2 = M × a Formula 1;

[0037] Among them, F2 is the inertial force, M is the moving mass, and a is the acceleration; the acceleration a is obtained through the acceleration sensor 1 in step S2, and the moving mass can be directly obtained after the cutting device is formed, so the moving mass is a fixed value.

[0038] The moving mass is the sum of the masses of the objects directly and indirectly acting on the force sensor 4 between the force sensor 4 and the object to be cut. For example, the tool tip 6, the cover plate 5 for fixing the tool tip 6, and screws and other objects are directly fixed on the force sensor 4 or fixed on the force sensor 4 through indirect fixing methods. Direct fixing means that objects such as the cover plate 5 are directly fixed on the force sensor 4 through screws, and indirect fixing means that objects such as the tool tip 6 are fixed on the cover plate 5 and the cover plate 5 is fixed on the force sensor 4.

[0039] S4. Calculate the actual cutting force, and calculate it through formula 2.

[0040] F1 = F - F2, Equation 2;

[0041] Where F is the cutting force of the tool tip, F1 is the actual cutting force, and F2 is the inertial force;

[0042] Through the above three steps, the cutting force F of the tool tip is obtained by measuring with the force sensor 4 in step S1, and the inertial force F2 is obtained by calculation in step S3.

[0043] S5. Calculate the tool feed. The acceleration value obtained in step S2 can be integrated twice to obtain the tool feed. Operations are carried out through Equation 3 and Equation 4.

[0044]

[0045]

[0046] Where a is the measured acceleration, V is the velocity, and S is the tool feed.

[0047] The above steps S1 to S5 are calculated by a computer and can be almost synchronously completed.

[0048] Based on the above compound intelligent detection method, an intelligent cutting device is designed. As Figure 2 shown, the cutting device includes an annular base 7, a tool tip assembly disposed at one end of the annular base 7, and an annular piezoelectric actuator 2 fixed inside the annular base 7 and abutting against the tool tip assembly. The tool tip assembly includes a flexible hinge 3 fixed to the end of the annular base 7, an acceleration sensor 2 fixed to the flexible hinge 3, a force sensor 4 fixed to the flexible hinge 3, and a tool tip 6 disposed on the force sensor 4. As Figure 3 shown, the flexible hinge 3 for the cutting device is circular and includes a fixed portion 31 located on the circumference and in a ring shape, a working portion 32 located in the middle of the ring of the fixed portion 31, and an elastic portion 33 disposed in the radial direction of the flexible hinge 3. The elastic portion 33 is used for connecting the fixed portion 31 and the working portion 32. The fixed portion 31 is fixed to the end face of the annular base 7 by screws; the tool tip 6 can be directly fixed to the force sensor 4 or indirectly fixed to the force sensor 4 by other means. The annular piezoelectric actuator 2 abuts against the working portion 32 of the flexible hinge 3. The force sensor 4 detects the force borne by the tool tip 6 and gives feedback. The acceleration sensor 1 detects the acceleration on the flexible hinge 3 and gives feedback. The two feedbacks are calculated by a computer to obtain the inertial force, the actual cutting force, and the tool feed.

[0049] Since during the cutting process, the cutting force acts entirely on the working part 32 of the flexible hinge 3, in order to improve the measurement accuracy, both the force sensor 4 and the acceleration sensor 1 need to be arranged on the working part 32 of the flexible hinge 3. The force sensor 4 is arranged on the outer side of the working part 32, that is, on the end face close to the object to be cut, and the acceleration sensor 1 is arranged on the inner side of the working part 32, that is, on the end face far from the object to be cut; a cover plate 5 is arranged between the tool head 6 and the force sensor 4, the tool head 6 is fixed on the cover plate 5, and the cover plate 5 is fixed on the working part 32 of the flexible hinge 3 by screws passing through the cover plate 5 and the force sensor 4, as Figure 4 shown above, the cover plate 5 is composed of two parts, including a top plate 51 for fixing the tool head 6 and baffle plates 52 extending from both sides of the top plate 51 towards the flexible hinge 3. The baffle plates 52 cover the working part 32 and do not contact the working part 32. An annular groove 54 is arranged at the end of the baffle plate 52, and a rubber sealing ring is placed in the annular groove 54. The top plate 51 is mainly for facilitating the fixed connection of the tool head 6, while the baffle plates 52 are mainly for preventing waste chips and cutting fluid during the cutting process from affecting the force sensor 4. The use of the rubber sealing ring can isolate the force sensor 4 from the external cutting environment and extend the service life of the force sensor 4.

[0050] Regarding the positioning of the force sensor 4 and the annular piezoelectric actuator 2, as Figure 3 shown, a first positioning groove 34 is opened on the end face of the working part 32 close to the force sensor 4, as Figure 4 shown, a second positioning groove 53 is opened on the end face of the cover plate 5 close to the force sensor 4. The first positioning groove 34 and the second positioning groove 53 are opposite to each other. The force sensor 4 is arranged in the first positioning groove 34 and the second positioning groove 53 and is fixed on the working part 32 by applying a pre-tightening force with screws. The first positioning groove 34 and the second positioning groove 53 can also be slightly larger than the two end faces of the force sensor 4, and the sizes and positions of the first positioning groove 34 and the second positioning groove 53 are determined according to the actual size of the force sensor 4. In this solution, the outer shape of the force sensor 4 is selected as cylindrical and is positioned at the center of the working part 32; a third positioning groove is opened on the end face of the working part 32 far from the force sensor 4, and the end of the annular piezoelectric actuator 2 is clamped in the third positioning groove 35. The third positioning groove 35 is circular or annular, and the end of the annular piezoelectric actuator 2 and the third positioning groove 35 are tightly fixed by insulating glue; the acceleration sensor 1 is arranged on the end face of the working part 32 of the flexible hinge 3 and far from the force sensor 4, and the acceleration sensor 1 is located at the center position of the flexible hinge 3.

[0051] In this solution, the moving mass mentioned in the detection method is the sum of the masses of the tool head 6, the cover plate 5, and the screws fixing the tool head 6 and the cover plate 5. Therefore, the moving mass can be obtained after the cutting device is assembled.

[0052] In summary, through the above detection method and the cutting device designed by this detection method, the acceleration sensor 1 can be used to detect the acceleration during the machining process in real time, so as to calculate the accurate inertial force value; through F1 = F - F2, the accurate actual cutting force F1 can be calculated, and both the cutting force F of the tool tip and the inertial force F2 can be obtained in real time. Therefore, the actual cutting force F1 is relatively accurate and can be obtained in real time; the tool feed during the machining process can be obtained by integrating the acceleration, without the need for a displacement sensor; the acceleration sensor 1 is easy to install and only needs to be fixed on the flexible hinge 3, without the need for high-precision cooperation like a displacement sensor, reducing the overall machining difficulty, assembly difficulty and cost of the mechanism.

[0053] It should be emphasized that: the above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A compound intelligent detection method for detecting the cutting force and the cutting feed of a quick tool servo cutting device, characterized in that, the cutting device includes an annular base (7), a tool head assembly arranged at one end of the annular base (7), and an annular piezoelectric actuator (2) fixed inside the annular base (7) and abutted against the tool head assembly. The tool head assembly includes a flexible hinge (3) fixed to the end of the annular base (7), an acceleration sensor (1) fixed to the flexible hinge (3), a force sensor (4) fixed to the flexible hinge (3), and a tool head (6) arranged on the force sensor (4). The annular piezoelectric actuator (2) abuts against the flexible hinge (3). The force sensor (4) detects the force borne by the tool head (6) and feeds it back. The acceleration sensor (1) detects the acceleration on the flexible hinge (3) and feeds it back to calculate the inertial force, the actual cutting force and the tool feed. The flexible hinge (3) is circular and includes a fixing part (31) located on the circumference, a working part (32) located in the middle, and an elastic part (33) connecting the fixing part (31) and the working part (32). The fixing part (31) is fixedly connected to the annular base (7). The force sensor (4), the tool head (6) and the acceleration sensor (1) are fixed on the working part (32). The annular piezoelectric actuator (2) abuts against the working part (32). The steps of this method are as follows, S1. Detect the cutting force of the tool head, which is directly obtained through the force sensor (4) in the cutting device; S2. Detect the acceleration, and obtain the acceleration through the acceleration sensor (1) arranged in the cutting device; S3. Calculate the inertial force, obtain the moving mass on the force sensor (4), and calculate the inertial force through formula 1, F2 = M × a Formula 1; wherein, F2 is the inertial force, M is the moving mass, and a is the acceleration; the moving mass is the sum of the masses of the objects directly and indirectly acting on the force sensor (4) and arranged between the force sensor (4) and the object to be cut; S4. Calculate the actual cutting force, which is calculated through formula 2, F1 = F - F2 Formula 2; wherein, F is the cutting force of the tool head, F1 is the actual cutting force, and F2 is the inertial force; S5. Calculate the tool feed, and obtain the tool feed through integral operation of the acceleration.

2. The compound intelligent detection method according to claim 1, characterized in that, a cover plate (5) is arranged between the tool head (6) and the force sensor (4). The tool head (6) is fixed to the cover plate (5). The cover plate (5) is fixed to the working part (32) of the flexible hinge (3) through screws passing through the cover plate (5) and the force sensor (4).

3. The compound intelligent detection method according to claim 2, characterized in that, A first positioning groove (34) is formed on the end face of the working part (32) close to the force sensor (4), and a second positioning groove (53) is formed on the end face of the cover plate (5) close to the force sensor (4). The first positioning groove (34) is opposite to the second positioning groove (53), and the force sensor (4) is arranged in the first positioning groove (34) and the second positioning groove (53).

4. The compound intelligent detection method according to claim 2, characterized in that the cover plate (5) includes a top plate (51) for fixing the tool bit (6) and baffles (52) extending from both sides of the top plate (51) towards the flexible hinge (3). The baffles (52) cover the working part (32); an annular groove (54) is arranged at the end of the baffle (52), and a sealing ring is placed in the annular groove (54).

5. The compound intelligent detection method according to claim 1, characterized in that a third positioning groove is formed on the end face of the working part (32) far from the force sensor (4), and the end of the annular piezoelectric actuator (2) is clamped in the third positioning groove.

6. The compound intelligent detection method according to claim 1, characterized in that the acceleration sensor (1) is arranged on the end face of the flexible hinge (3) far from the force sensor (4) and is located at the central position of the flexible hinge (3).

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