Intelligent tool holder and system for measuring cutting force and cutting vibration in real time

Abstract

The application discloses a kind of intelligent tool shank for measuring cutting force and cutting vibration in real time and system, it is related to signal monitoring technical field, including tool shank main body, tool shank main body outside is equipped with the circuit carrier for installing data acquisition system, shell is installed on the outside of the circuit carrier;Multiple detection beam structures are circumferentially distributed in the tool shank main body, and piezoelectric film force sensor is fixed on the surface of detection beam structure;Multiple vibration sensors are installed on the side of the circuit carrier, and vibration sensor and piezoelectric film force sensor are all connected with data acquisition system.The application uses piezoelectric film sensor as sensitive element, and designs elastic strain structure to collect force signal, and uses vibration sensor to collect vibration signal;Collection-transmission is integrated, three-dimensional cutting force signal and two-way vibration signal in monitoring cutting process can be realized.

Description

Technical Field

[0001] This invention relates to the field of signal monitoring technology, and in particular to an intelligent tool holder and system for real-time measurement of cutting force and cutting vibration. Background Technology

[0002] In the field of machining, high-precision machining places high demands on the real-time performance of monitoring systems. As the machining terminal in the cutting field, intelligent monitoring of tool status is of great significance for improving machining efficiency and quality. Traditional sensors are generally scattered around the worktable. This monitoring method, due to the large number of devices, complex operation, and large structure and size, is difficult to apply to the production line, which restricts the development of monitoring systems. However, intelligent measuring tool holders that integrate traditional sensors not only solve the problems of numerous, messy, and complicated wiring harnesses in traditional methods, but also have the advantages of simple operation.

[0003] In existing technologies, most vibration-measuring and intelligent force-measuring tool holders use strain gauges or rigid piezoelectric crystals as sensitive elements. Strain gauge tool holders detect force signals based on the strain effect of metals, but have a narrow measurement range and low linearity, making them unsuitable for measuring high dynamic forces. Piezoelectric tool holders measure force signals based on the piezoelectric effect of materials, and there are already relatively mature commercial solutions; however, piezoelectric crystals are expensive, have a significant impact on the tool holder structure, and are difficult to maintain.

[0004] Thin-film polyvinylidene fluoride piezoelectric sensors (PVDF piezoelectric films) represent a promising technology for surface strain measurement. They combine the wide bandwidth, high sensitivity, and high dynamic range of piezoelectric materials with low cost and easy installation. Current technologies, such as the wireless force measurement system and method for milling disclosed in patent (CN 108481088 A), use piezoelectric films as the sensing element, but do not specifically address the design of the tool holder structure, making the measurement structure prone to significant deviations. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an intelligent tool holder and system for real-time measurement of cutting force and cutting vibration. It uses a piezoelectric thin film sensor as the sensing element, collects force signals based on a designed elastic strain structure, and collects vibration signals using a vibration sensor. The acquisition and transmission are integrated into one unit, enabling the monitoring of three-dimensional cutting force signals and two-dimensional vibration signals during the cutting process.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] In a first aspect, embodiments of the present invention provide an intelligent tool holder for real-time measurement of cutting force and cutting vibration, comprising a tool holder body, a circuit carrier for mounting a data acquisition system on the outer side of the tool holder body, and a housing mounted on the outer side of the circuit carrier; multiple detection beam structures are distributed circumferentially on the tool holder body, and piezoelectric thin film force sensors are fixed on the surface of the detection beam structures; multiple vibration sensors are mounted on the side of the circuit carrier, and both the vibration sensors and the piezoelectric thin film force sensors are connected to the data acquisition system.

[0008] As a further implementation, the main body of the circuit carrier is cylindrical, with multiple mounting spaces opened in its circumference to form a mounting cavity for the data acquisition system with the housing.

[0009] As a further implementation, multiple grooves are formed on the bottom side of the circuit carrier, and the vibration sensor is fixed in the grooves.

[0010] As a further implementation, the main body of the tool holder is also provided with a support beam structure in the circumference. The cross-section of the detection beam structure is a cross-shaped structure, and gaps are formed between adjacent beams, so that the gaps are distributed in a grid-like structure.

[0011] As a further implementation, the data acquisition system includes a signal amplification circuit, an analog-to-digital conversion circuit, a signal conditioning circuit, and a wireless transmission circuit connected in sequence, wherein the wireless transmission circuit is used to communicate with a host computer.

[0012] Each circuit is connected to a power supply circuit, and the piezoelectric film force sensor and vibration sensor are connected to a signal amplification circuit.

[0013] As a further implementation, the top of the housing is equipped with a power switch, a charging port, a signal indicator light, and a power indicator light connected to the power supply circuit.

[0014] As a further implementation, the signal indicator is connected to the wireless transmission circuit so that it lights up when the wireless transmission circuit establishes a connection with the host computer.

[0015] As a further implementation, the housing consists of side plates and a top plate and a bottom plate connected to the side plates.

[0016] As a further implementation, a collet is connected to the end of the tool holder body, and the collet is connected to a tool or a cap.

[0017] Secondly, embodiments of the present invention also provide a system for real-time measurement of cutting force and cutting vibration, including a machine tool and the aforementioned intelligent tool holder, wherein the intelligent tool holder is mounted on the machine tool spindle.

[0018] The beneficial effects of this invention are as follows:

[0019] (1) The tool holder body of the present invention is fitted with a circuit carrier for installing a data acquisition system on the outside. Multiple detection beam structures are distributed around the tool holder body. A piezoelectric thin film force sensor is fixed on the surface of the detection beam structure. Multiple vibration sensors are installed on the side of the circuit carrier, which can realize the monitoring of three-dimensional cutting force signal and two-dimensional vibration signal during the cutting process.

[0020] (2) The present invention sets up a data acquisition system, which generates strain through a piezoelectric thin film force sensor, generates charge between electrodes and transfers it to the information acquisition system, converts it into a voltage signal and outputs it to the host computer; the vibration sensor monitors the cutting vibration generated on the tool-tool holder-spindle system and converts the vibration signal into an electrical signal and transmits it to the host computer, thereby realizing the monitoring of cutting force signal and vibration signal.

[0021] (3) The tool holder body, circuit carrier, housing, etc. of the present invention adopt a detachable structure, which can be used with different types of machine tool spindles, and has the characteristics of wide applicability, convenient operation and low cost. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 This is a schematic diagram of the knife handle structure according to one or more embodiments of the present invention;

[0024] Figure 2 This is an exploded view of the knife handle according to one or more embodiments of the present invention;

[0025] Figure 3 This is a cross-sectional view of the tool holder according to one or more embodiments of the present invention;

[0026] Figure 4 This is a schematic diagram of the main structure of the knife handle according to one or more embodiments of the present invention;

[0027] Figure 5 This is a cross-sectional view AA of the knife handle body according to one or more embodiments of the present invention;

[0028] Figure 6 This is a schematic diagram of the circuit carrier structure according to one or more embodiments of the present invention;

[0029] Figure 7 This is a schematic diagram of the information acquisition system structure according to one or more embodiments of the present invention.

[0030] The components include: 1. Tool holder body; 1a. Detection beam structure; 1b. Support beam structure; 2. Power switch; 3. Charging port; 4. Signal indicator light; 5. Power indicator light; 6. Top plate; 7. Piezoelectric film force sensor; 8. Circuit carrier; 9. Vibration sensor; 10. Counterweight; 11. First fixing screw; 12. Base plate; 13. Second fixing screw; 14. Side plate; 15. Third fixing screw; 16. Collet; 17. Cap; 18. Power supply circuit; 19. Signal amplification circuit; 20. Analog-to-digital conversion circuit; 21. Signal conditioning circuit; 22. Wireless transmission circuit; 23. Groove; 24. Threaded hole. Detailed Implementation

[0031] Example 1:

[0032] This embodiment provides an intelligent tool holder for real-time measurement of cutting force and cutting vibration, such as... Figures 1-3 As shown, it includes a tool holder body 1, a housing, a piezoelectric thin film force sensor 7, a circuit carrier 8, a vibration sensor 9, a data acquisition system, etc. The circuit carrier 8 is sleeved on the outside of the tool holder body 1 and set inside the housing. In use, the tool holder body 1 is installed on the machine tool spindle through the HSK standard tool holder connector.

[0033] like Figure 2 and Figure 3 As shown, a collet 16 is installed at the end of the tool holder body 1. The collet 16 is used to hold the tool. When no tool is installed, a cap 17 is installed on the outside of the collet 16.

[0034] The housing is used to protect the internal signals from external interference and also serves to provide waterproofing and corrosion resistance. In this embodiment, the housing is a detachable structure, including a top plate 6, a bottom plate 12, and a side plate 14. With the installation state of the tool handle as a reference, the top plate 6 is installed on the top of the side plate 14, and the bottom plate 12 is installed on the bottom of the side plate 14, forming a hollow columnar structure. The top plate 6 and the bottom plate 12 are respectively provided with holes for the tool handle body 1 to pass through, and the bottom plate 12 is connected to the tool handle body 1 by threads.

[0035] like Figure 1 and Figure 2 As shown, the top plate 6 has multiple through holes for installing the power switch 2, charging port 3, signal indicator 4, and power indicator 5.

[0036] The handle body 1 is fixed to the base plate 12, the circuit carrier 8 is fixed to the base plate 12, and the circuit carrier 8 is fixed to the side plate 14 by screws. For ease of description, this embodiment uses "first", "second" and "third" to distinguish them. That is, the handle body 1 is connected to the base plate 12 by multiple first fixing screws 11, the circuit carrier 8 is connected to the base plate 12 by multiple second fixing screws 13, and the circuit carrier 8 is connected to the side plate 14 by multiple third fixing screws 15.

[0037] A piezoelectric thin-film force sensor 7 is installed on the outer side of the tool holder body 1, such as Figure 4 and Figure 5 As shown, multiple detection beam structures 1a and multiple support beam structures 1b are uniformly machined in the circumferential direction in the middle of the cylindrical tool holder. There are uniformly distributed gaps between adjacent beams. A piezoelectric thin film force sensor 7 is attached to the side wall of the detection beam structure 1a.

[0038] In this embodiment, four detection beam structures 1a and four support beam structures 1b are respectively provided. The cross-section of the detection beam structure 1a is arranged in a cross shape. The cross-shaped detection beam structure makes the piezoelectric film face the X and Y directions, which facilitates force decoupling and ensures sensitivity. The support beam structure ensures that the tool holder has sufficient rigidity.

[0039] The outer surface of the detection beam structure 1a is machined into a flat surface to fix the piezoelectric thin-film force sensor 7, which is used to measure the force in the X direction, the force in the Y direction, and the torque about the Z axis; for example Figure 5 As shown, the gaps between the four detection beam structures 1a and the four support beam structures 1b are distributed in a grid pattern; the evenly distributed detection beams and gaps can ensure the dynamic balance of the tool holder rotor system.

[0040] like Figure 6 As shown, the top of the circuit carrier 8 has four holes corresponding to the top plate 6 for installing the power switch 2, charging port 3, signal indicator 4, and power indicator 5. The power switch 2, charging port 3, signal indicator 4, and power indicator 5 are connected to the internal circuitry of the circuit carrier 8. An information acquisition system is installed inside the circuit carrier 8 to realize the conversion of strain signal to charge signal to voltage signal and perform wireless transmission. The circuit carrier 8 is fixed to the tool holder body by the base plate 12 to ensure the normal operation of the circuit.

[0041] During the machining process, the tool holder body 1 is connected to the spindle. The spindle-tool holder-tool system rotates to perform cutting. The cutting edge of the tool is subjected to a reaction force that is transmitted to the tool holder, causing the tool holder to produce strain. At the same time, the piezoelectric film force sensor 7 produces strain and generates charge between the electrodes, which is transmitted to the information acquisition system, converted into a voltage signal, and output to the host computer.

[0042] Furthermore, the main body of the circuit carrier 8 is a cylindrical structure with four mounting spaces circumferentially opened in its middle, forming a mounting cavity with the side plate 14 for the information acquisition system and counterweight 10, etc. Multiple grooves 23 are distributed along the outer circumference of the circuit carrier 8, and each groove 23 has a threaded hole 24 on its side. The vibration sensor 9 and circuit board are fixed in the groove 23 with bolts for measuring vibration signals. A certain gap is left between the groove and the side plate 14 for the arrangement of the vibration sensor 9 circuitry. Vibration signals in the X and Y directions are measured through two vibration sensors 9.

[0043] In this embodiment, each vibration sensor 9 is a PCB board containing an Analog Devices ADXL1001 vibration sensor chip and a low-pass filter circuit, placed in the X and Y directions respectively. For balance, a blank PCB board is installed on the opposite side as a counterweight 10. This structure is close to the machining area, resulting in more accurate signal acquisition; it has less impact on the main structure of the tool holder and is easy to install and maintain.

[0044] During machining, the tool vibration signal is transmitted to the tool holder body 1, which in turn drives the circuit carrier 8 to vibrate. Two vibration sensors 9 monitor and collect the vibration signals in the X and Y directions, and transmit them to the information acquisition system through the circuit.

[0045] like Figure 7 As shown, the information acquisition system includes a power supply circuit 18, a signal amplification circuit 19, an analog-to-digital converter circuit 20, a signal conditioning circuit 21, and a wireless transmission circuit 22. A piezoelectric film force sensor 7 and a vibration sensor 9 are connected to the signal amplification circuit 19. The signal amplification circuit 19, the analog-to-digital converter circuit 20, and the signal conditioning circuit 21 are connected in sequence, and the signal conditioning circuit 21 is connected to a host computer via the wireless transmission circuit 22. All of the above circuits are connected to the power supply circuit 18, and the power switch 2, charging port 3, signal indicator light 4, and power indicator light 5 are also connected to the power supply circuit 18.

[0046] Before the processing monitoring begins, the power supply circuit 18 is controlled by the power switch 2 to supply power to other modules. If the power supply is successful, the power indicator light 5 will light up. If the power supply is insufficient, the measuring tool holder can be charged through the charging port 3. After power is supplied, the wireless transmission circuit 22 is turned on. The WIFI is searched according to the preset IP address and port number. The host computer program is opened and the WIFI service is activated. The wireless transmission circuit 22 establishes a connection with the host computer, the signal indicator light 4 lights up, and the preparation work is completed.

[0047] During the machining monitoring process, the vibration sensor 9 monitors the cutting vibration generated on the tool-tool holder-spindle system and converts the vibration signal into an electrical signal. The electrical signal is amplified by the signal amplification circuit 19, converted into a digital signal by the analog-to-digital conversion circuit 20, and then preliminarily processed by the signal conditioning circuit 21. The wireless transmission circuit 22 transmits the processing result to the host computer.

[0048] The host computer loads the data, uses an algorithm to calibrate the data peak value, performs data filtering, and processes the data into voltage values. These values ​​are then substituted into the transformation matrix and system transfer function determined by the calibration test to obtain three-dimensional force data and torsional torque.

[0049] It should be noted that the tool holder body 1 needs to undergo calibration tests. During cutting, data from the piezoelectric film force sensor 7 and the tool holder output data are collected. Based on both, the system transfer function is determined, the matrix conversion coefficient from cutting force to voltage reading is determined, and a corresponding filtering method is proposed.

[0050] This embodiment has a simple structure and minimal impact on the machining process. It can monitor three-dimensional cutting force signals and two-dimensional vibration signals during the cutting process. The split design can be matched with different models of machine tool spindles.

[0051] Example 2:

[0052] This embodiment provides a system for real-time measurement of cutting force and cutting vibration, including the intelligent tool holder described in the embodiment and a machine tool, wherein the intelligent tool holder is mounted on the machine tool spindle.

[0053] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A smart tool holder for real-time measurement of cutting force and cutting vibration, characterized in that, The device includes a tool holder body, an outer sleeve of which is fitted with a circuit carrier for mounting a data acquisition system, and a housing is mounted on the outer side of the circuit carrier. Multiple detection beam structures are distributed circumferentially around the tool holder body, and piezoelectric thin-film force sensors are fixed to the surface of each detection beam structure. Multiple vibration sensors are mounted on the side of the circuit carrier, and both the vibration sensors and the piezoelectric thin-film force sensors are connected to the data acquisition system. The main body of the circuit carrier is cylindrical, with multiple installation spaces opened around its circumference to form an installation cavity for the data acquisition system with the housing; multiple grooves are opened on the bottom side of the circuit carrier, and vibration sensors are fixed in the grooves. Multiple detection beam structures and multiple support beam structures are uniformly machined in the circumferential direction in the middle of the cylindrical tool holder. There are uniformly distributed gaps between adjacent beams. A piezoelectric thin film force sensor is attached to the side wall of the detection beam structure. Four detection beam structures and four support beam structures are set. The cross-section of the detection beam structure is distributed in a cross shape. The gaps between the four detection beam structures and the four support beam structures are distributed in a grid-like structure.

2. The intelligent tool holder for real-time measurement of cutting force and cutting vibration according to claim 1, characterized in that, The data acquisition system includes a signal amplification circuit, an analog-to-digital conversion circuit, a signal conditioning circuit, and a wireless transmission circuit connected in sequence. The wireless transmission circuit is used to communicate with a host computer. Each circuit is connected to a power supply circuit, and the piezoelectric film force sensor and vibration sensor are connected to a signal amplification circuit.

3. The intelligent tool holder for real-time measurement of cutting force and cutting vibration according to claim 2, characterized in that, The top of the housing is equipped with a power switch, a charging port, a signal indicator light, and a power indicator light, all connected to the power supply circuit.

4. The intelligent tool holder for real-time measurement of cutting force and cutting vibration according to claim 3, characterized in that, The signal indicator light is connected to the wireless transmission circuit and illuminates when the wireless transmission circuit establishes a connection with the host computer.

5. The intelligent tool holder for real-time measurement of cutting force and cutting vibration according to claim 1, characterized in that, The shell consists of side plates and a top plate and a bottom plate connected to the side plates.

6. The intelligent tool holder for real-time measurement of cutting force and cutting vibration according to claim 1, characterized in that, The end of the handle body is connected to a collet, which is connected to a cutting tool or a cap.

7. A system for real-time measurement of cutting force and cutting vibration, characterized in that, The invention includes a machine tool and a smart tool holder as described in any one of claims 1-6, wherein the smart tool holder is mounted on the machine tool spindle.

Images