Load detecting device and tool holder

Abstract

To provide a load detection device and a tool holder for immediately detecting a load state and generating a corresponding detection signal.SOLUTION: A load-sensing device with a defined central axis, the load-sensing device comprising a main body having a cylindrical shape and an annular accommodating groove recessed on an outer circumferential surface of the main body, two load-sensing modules spaced apart from each other along the central axis and disposed in the annular accommodating groove of the main body, and a sealing material disposed in the annular accommodating groove of the main body to cover the load-sensing modules, wherein each of the load-sensing modules comprises a plurality of load-sensing units, and each of the load-sensing units comprises two strain sensing elements symmetrically arranged about the central axis; Each of the strain detecting elements of one of the load detecting modules and each of the strain detecting elements of the other of the load detecting modules are arranged corresponding to each other in an axial direction of the main body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tool holder, and more particularly to a tool holder equipped with a load detection device. [Background technology]

[0002] Traditionally, tool holders have played an important role in the production of precision parts, connecting the spindle of a processing machine with a tool to transmit the rotational force of the spindle to the tool for cutting. When cutting an object with a tool, vibrations caused by the operation of the processing machine and contact with the uneven surface of the object cause momentary stress fluctuations in the tool and tool holder, which can easily affect the accuracy of the tool holder driving the tool to perform cutting and even shorten the lifespan of the tool holder and tool.

[0003] Furthermore, when the type of workpiece is different, it is necessary to change to an appropriate tool for cutting, which changes the force applied to the tool holder. Even with tools of the same standard, differences in quality can cause uneven loads, which also affect the accuracy and lifespan of cutting with that tool holder. It is difficult for on-site workers to immediately determine these situations, so technology that can provide real-time monitoring information according to the load status is a technical challenge that related industries are currently focusing on. Summary of the Invention [Problem to be solved by the invention]

[0004] In view of this, an object of the present invention is to provide a load detection device and a tool holder that can instantly detect a load state and generate a corresponding detection signal.

[0005] In order to achieve the above-mentioned object, the present invention provides a load detection device having a defined central axis, comprising: a main body having a cylindrical shape and an annular accommodating groove recessed into its outer peripheral surface; two load detection modules arranged in the annular accommodating groove of the main body at intervals along the central axis; and a sealing material arranged in the annular accommodating groove of the main body so as to cover the load detection modules, wherein the load detection modules include a plurality of load detection units, each having two strain detection elements arranged symmetrically about the central axis, and each strain detection element of one of the load detection modules and each strain detection element of the other load detection module are arranged correspondingly in the axial direction of the main body.

[0006] The present invention also provides a tool holder for connecting a processing spindle and a tool, comprising: the load detection device; a tool holder head connected to one end of a main body of the load detection device and connected to the processing spindle; and a chuck connected to the other end of the main body of the load detection device and connected to the tool.

[0007] According to the present invention, the load detection device and tool holder can instantly detect the load state using two load detection modules installed on the main body, sense load changes at different positions on the main body in real time, and determine whether the load detection device is tilted or vibrating, thereby effectively monitoring and analyzing the work situation in real time. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view of a tool holder according to a preferred embodiment of the present invention; FIG. [Figure 2] FIG. 2 is a schematic diagram of the components of the preferred embodiment. [Figure 3] FIG. 3 is an exploded view of the components shown in FIG. 2. [Figure 4] FIG. 2 is a perspective view of the preferred embodiment as seen from another angle. [Figure 5] FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 4. [Figure 6] FIG. 2 is a schematic diagram of the inner cylinder and the circuit board unit of the preferred embodiment. [Figure 7] FIG. 7 is a cross-sectional view taken along line 7-7 of FIG. 2. [Figure 8] FIG. 2 is a schematic diagram of components of the preferred embodiment, showing the arrangement of a load detection module. [Figure 9] FIG. 2 is a schematic diagram of a first load detection unit of the preferred embodiment. [Figure 10] FIG. 4 is a circuit diagram of the first load detection unit of the preferred embodiment. [Figure 11] FIG. 4 is a schematic diagram of a second load detection unit of the preferred embodiment. [Figure 12] FIG. 4 is a circuit diagram of the second load detection unit of the preferred embodiment. [Figure 13] FIG. 2 is a schematic diagram of the tensile force detection unit of the preferred embodiment. [Figure 14] FIG. 2 is a circuit diagram of the tensile force detection unit of the preferred embodiment. [Figure 15] FIG. 2 is a schematic diagram of the torque detection unit of the preferred embodiment. [Figure 16] FIG. 2 is a circuit diagram of the torque detection unit of the preferred embodiment. [Figure 17] FIG. 2 is a schematic diagram of a first circuit board according to the preferred embodiment. [Figure 18] FIG. 2 is a schematic diagram of a second circuit board according to the preferred embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] To more clearly explain the present invention, preferred embodiments will be described in detail below with reference to the drawings. As shown in FIGS. 1 to 5, a tool holder 1 according to a preferred embodiment of the present invention includes a tool holder head 200, a chuck 300, and a load detection device 100. The tool holder head 200 has a first through-hole 200a communicating with both ends and is connected to a machining spindle (not shown). The tool holder head 200 is connected to one end of the load detection device 100, and the chuck 300 has a second through-hole 300a communicating with both ends and is connected to a tool 2 and the other end of the load detection device 100. In this embodiment, the tool holder 1 is a rotary tool holder.

[0010] The load detection device 100 has a defined central axis A and includes a main body 10, a plurality of balance weights 20, two load detection modules 30, an inner cylinder 40, a circuit board unit 50, and a sealing material 80.

[0011] One end of the body 10 is connected to the tool holder head 200 along the central axis A, and the other end is connected to the chuck 300 along the central axis A. The body 10 is cylindrical and has a hollow portion 11. The hollow portion 11 connects both ends of the body 10 along the central axis A and forms a first opening 11a and a second opening 11b. The first opening 11a communicates with the first through-hole 200a of the tool holder head 200, and the second opening 11b communicates with the second through-hole 300a of the chuck 300. The outer circumferential surface 12 of the body 10 is recessed with an annular accommodating groove 12a and multiple wiring grooves 12b, and each wiring groove 12b communicates with the annular accommodating groove 12a. The body 10 is provided with multiple first wiring holes 16, multiple insertion holes 13, at least one first coupling hole 14, and a first light-transmitting hole 15. Each first wiring hole 16 is provided in each wiring groove 12b and communicates with the hollow portion 11. A plurality of insertion holes 13 are arranged around the second opening 11b and are for fitting balance weights 20. At least one first coupling hole 14 communicates with the hollow portion 11 and is used for coupling with the inner tube 40. The first light-transmitting hole 15 communicates with the hollow portion 11 and is used to couple a light-guiding column (not shown) to transmit light. In this embodiment, the material of the main body 10 is metal. The number of insertion holes 13 corresponds to the number of balance weights 20, and the numbers of balance weights 20 and insertion holes 13 can be set as needed, allowing dynamic balance adjustment.

[0012] As shown in Figures 8 to 16, two load detection modules 30 are arranged at an interval along the central axis A in the annular receiving groove 12a of the main body 10. Each load detection module 30 detects a load applied to the tool holder 1 and outputs at least one detection signal. In this embodiment, there are a plurality of detection signals, and the first detection signal V S1 , the second detection signal V S2 , the third detection signal V S3 , and the fourth detection signal V S4 Includes.

[0013] The two load detection modules 30 have the same structure, and the following description focuses on one load detection module 30. The load detection module 30 includes multiple load detection units, each with two strain detection elements. The strain detection elements of one load detection module 30 and the strain detection elements of the other load detection module 30 are axially arranged in the annular housing groove 12a. In this embodiment, each strain detection element includes a flexible substrate and a strain detection structure provided on the flexible substrate. As shown in FIGS. 3 and 4, the strain detection elements are attached to the groove surface of the annular housing groove 12a. These strain detection elements are connected by a flexible circuit board (FPC) and multiple wiring (not shown), which transmits detection signals through the first wiring hole 16. The load detection units of the load detection module 30 include a first load detection unit 32, a second load detection unit 34, a tension detection unit 36, and a torque (torsion) detection unit 38.

[0014] The first load detection unit 32 detects the load along the first axis L1 direction of the tool holder 1 and outputs a first detection signal V S1The first axis L1 is perpendicular to the central axis A. The first load detection unit 32 has two first strain detection elements 321, which are arranged symmetrically along the first axis L1. The first strain detection elements 321 in one load detection module 30 and the first strain detection elements 321 in the other load detection module 30 are arranged in a corresponding relationship along the axial direction of the main body 10 and do not intersect. Each first strain detection element 321 includes a first flexible substrate 321a and two first strain detection structures R1 to R4 provided on the first flexible substrate 321a, and these strain detection structures R1 to R4 have predetermined resistance values. As a result, the first load detection units 32 are connected by wiring on the flexible circuit board to form a Wheatstone bridge configuration (first Wheatstone bridge) shown in FIG. 10. The first Wheatstone bridge has a first arm and a second arm, and the first strain detection structures R3 and R4 of one first strain detection element 321 are arranged on the upper arm of the first arm and the lower arm of the second arm, respectively, while the first strain detection structures R1 and R2 of the other first strain detection element 321 are arranged on the lower arm of the first arm and the upper arm of the second arm, respectively. When the tool holder 1 is subjected to stress along the first axis L1, the resistance values ​​of the first strain detection structures R1 to R4 change. That is, when the tool holder 1 is subjected to a compressive force on one side and a tensile force on the other side in the direction of the first axis L1, the resistance value of one first strain detection element 321 of the first load detection unit 32 on the compression side becomes smaller than the resistance value of the other first strain detection element 321, and as a result, the corresponding first detection signal V S1 Furthermore, the greater the stress along the first axis L1, the greater the first detection signal V S1 The absolute value of also increases. The resistance values ​​of the two first strain sensing elements 321 change relatively (the resistance values ​​of the two sensing structures R1, R2 or R3, R4 of one first strain sensing element 321 increase, and the resistance value of the sensing structures R3, R4 or R1, R2 of the other first strain sensing element 321 decrease), and in combination with the Wheatstone bridge structure, the first sensing signal V S1 can be amplified, resulting in the first detection signal V S1The sensitivity can be effectively improved.

[0015] The second load detection unit 34 detects the load along the second axis L2 direction of the tool holder 1 and outputs a corresponding second detection signal V S2 The second axis L2 is perpendicular to the central axis A and the first axis L1. The second load detection unit 34 has two second strain detection elements 341, which are arranged symmetrically along the second axis L2. Each second strain detection element 341 of one load detection module 30 and each second strain detection element 341 of the other load detection module 30 are arranged in a corresponding relationship along the axial direction of the main body 10 and do not intersect. Each second strain detection element 341 includes a second flexible substrate 341a and two second strain detection structures R5 to R8 provided on the second flexible substrate 341a. These second strain detection structures R5 to R8 have predetermined resistance values. As a result, the second load detection units 34 are connected by wiring on the flexible circuit board to form a Wheatstone bridge configuration (second Wheatstone bridge) shown in FIG. 12. The second Wheatstone bridge has a first arm and a second arm, and the second strain sensing structures R7 and R8 of one second strain sensing element 341 are arranged on the upper arm of the first arm and the lower arm of the second arm, respectively, while the second strain sensing structures R5 and R6 of the other second strain sensing element 341 are arranged on the lower arm of the first arm and the upper arm of the second arm, respectively. When the tool holder 1 is subjected to stress along the second axis L2, the resistance values ​​of the second strain sensing structures R5 to R8 change. That is, when the tool holder 1 is subjected to a compressive force on one side and a tensile force on the other side in the direction of the second axis L2, the resistance value of one second strain sensing element 341 on the compression side becomes smaller than the resistance value of the other second strain sensing element 341, thereby generating a corresponding second sensing signal V S2 Furthermore, the greater the stress along the second axis L2, the greater the second detection signal V S2The absolute value of also increases. The resistance values ​​of the two second strain sensing elements 321 change relatively (the resistance values ​​of the two sensing structures R5, R6 or R7, R8 of one second strain sensing element 341 increase, and the resistance value of the sensing structures R7, R8 or R5, R6 of the other second strain sensing element 331 decrease), and in combination with the Wheatstone bridge structure, the second sensing signal V S2 can be amplified, resulting in a second sensed signal V S2 The sensitivity can be effectively improved.

[0016] The tension detection unit 36 ​​detects the tension force along the central axis A of the tool holder 1 and outputs a corresponding third detection signal V S3 The tensile detection unit 36 ​​has two tensile detection elements 361, which are arranged symmetrically around the central axis A. The tensile detection elements 361 of one load detection module 30 and the tensile detection elements 361 of the other load detection module 30 are arranged in a corresponding relationship in the axial direction of the main body 10 and do not intersect. Each tensile detection element 361 is arranged between the first strain detection element 321 and the second strain detection element 341. Each tensile detection element 361 includes a third flexible substrate 361a and two tensile detection structures R9 to R12 provided on the third flexible substrate 361a, and these tensile detection structures R9 to R12 have predetermined resistance values. As a result, the tensile detection unit 36 ​​is connected by wiring on the flexible circuit board to form a Wheatstone bridge (third Wheatstone bridge) as shown in FIG. 14. The tensile detection structures R11 and R12 of one of the tensile detection elements 361 are arranged on the upper arms of the first and second arms, and the tensile detection structures R9 and R10 of the other of the tensile detection elements 361 are arranged on the lower arms of the first and second arms. When the tool holder 1 is subjected to a tensile stress along the central axis A, the resistance value of each of the tensile detection elements 361 changes, thereby generating a third detection signal V S3 The greater the stress, the greater the third detection signal V S3 The absolute value of also becomes larger.

[0017] The torque detection unit 38 detects the torque applied to the tool holder 1 and generates a corresponding fourth detection signal V S4 The torque detection unit 38 has two torque detection elements 381, which are arranged symmetrically around the central axis A. The torque detection elements 381 of one load detection module 30 and the torque detection elements 381 of the other load detection module 30 are arranged in a corresponding relationship in the axial direction of the main body 10 and do not intersect. Each torque detection element 381 is arranged between the first strain detection element 321 and the second strain detection element 341. Each torque detection element 381 includes a fourth flexible substrate 381a and two torque detection structures R13 to R16 provided on the fourth flexible substrate 381a, and these torque detection structures R13 to R16 have predetermined resistance values. As a result, the torque detection units 38 are connected by wiring on the flexible circuit board to form a Wheatstone bridge (fourth Wheatstone bridge) shown in FIG. 16. The torque detection structures R15 and R16 of one torque detection element 381 are arranged on the upper arms of the first and second arms, and the torque detection structures R13 and R14 of the other torque detection element 381 are arranged on the lower arms of the first and second arms. When torque is applied to the tool holder 1, the resistance value of each torque detection element 381 changes, thereby generating a fourth detection signal V S4 The larger the torque, the larger the fourth detection signal V S4 The absolute value of also becomes larger.

[0018] The strain detection elements of one load detection module 30 and the strain detection elements of the other load detection module 30 are arranged in a corresponding relationship in the axial direction of the main body 10, without being intersected. Therefore, when the load detection device 100 is not deflected, tilted, or oscillating, the values ​​of the detection signals generated by the two load detection modules 30 are the same or similar. On the other hand, when the load detection device 100 is deflected, tilted, or oscillating, a clear difference occurs in the values ​​of the detection signals generated by the two load detection modules 30. This makes it possible to determine the state of the load detection device 100 (deflection, tilt, or oscillation) from the difference in the detection signals. In other embodiments, the number of load detection units in each load detection module 30 can be increased as needed to detect loads in various directions on the tool holder 1 in more detail.

[0019] As shown in FIGS. 3 to 7 , the inner cylinder 40 is disposed within the hollow portion 11 of the main body 10. The inner cylinder 40 has a housing space 41, with both ends communicating to form a third opening 41a and a fourth opening 41b. An end cap 40a is attached to the end of the inner cylinder 40 on the third opening 41a side to cover the third opening 41a. A third through hole 40a1 is formed in the end cap 40a, connecting the housing space 41, the first opening 11a, and the first through hole 200a of the tool holder head 200. The fourth opening 41b is connected to the second opening 11b and the second through hole 300a of the chuck 300. The housing space 41 has a first housing chamber 411, a second housing chamber 412, and a third housing chamber 413. The first housing chamber 411 and the third housing chamber 413 are located on either side of the second housing chamber 412 and are connected to each other. The inner tube 40 is provided with a plurality of second wiring holes 42, at least one second coupling hole 43, and a second light-transmitting hole 44. The number and positions of the second wiring holes 42 correspond to the number and positions of the first wiring holes 16 so that wiring can pass through. The number and positions of the second coupling holes 43 correspond to the number and positions of the first coupling holes 14. The second light-transmitting holes 44 communicate with the accommodation space 41 and are coupled to the light guide columns (not shown) corresponding to the first light-transmitting holes 15. In this embodiment, there are two at least one second coupling hole 43 and two at least one first coupling hole 14, and the second coupling hole 43 is a blind hole. Therefore, the main body 10 and the inner tube 40 can be securely coupled by fastening the corresponding at least one first coupling hole 14 and at least one second coupling hole 43 using a set screw. The inner tube 40 is made of plastic.

[0020] As shown in FIGS. 6, 7, 17, and 18, the circuit board unit 50 is disposed in the second housing chamber 412 of the housing space 41 of the inner cylinder 40. The circuit board unit 50 includes a first circuit board 51, a second circuit board 52, a power supply control module 53, a light-emitting element 54, a vibration detection module 56, a control module 57, and a wireless communication module 55. The first circuit board 51 has a first connector 511 for electrically connecting to the second circuit board 52, and the control module 57, the wireless communication module 55, and the vibration detection module 56 are provided on the first circuit board 51. The first connector 511 is electrically connected to the control module 57, the wireless communication module 55, and the two load detection modules 30. The second circuit board 52 has a second connector 521 for connecting to the first connector 511, and the power supply control module 53 and the light-emitting element 54 are disposed on the surface of the second circuit board 52 facing the first circuit board 51. The power supply control module 53 is connected to the battery module 60 and is electrically connected to the second connector 521 and the light emitting element 54, and supplies power to the control module 57, the wireless communication module 55, the vibration detection module 56, the two load detection modules 30, and the light emitting element 54. As a result, each load detection module 30 receives the input voltage V from the power supply control module 53. i receives the input voltage V i the first detection signal V S1 , the second detection signal V S2 , the third detection signal V S3 , and the fourth detection signal V S4 The battery module 60 includes two batteries 61, which are respectively disposed in the first and third housing chambers 411 and 413. The first and second light-transmitting holes 15 and 44 are located at positions corresponding to the light-emitting element 54, and light from the light-emitting element 54 is radiated to the outside through the first and second light-transmitting holes 15 and 44 via the light-guiding rod.

[0021] The control module 57 includes an analog-to-digital converter 571 and a controller 572. The controller 572 is, for example, a microcontroller, and is electrically connected to the analog-to-digital converter 571 and the vibration detection module 56. The analog-to-digital converter 571 is electrically connected to the two first strain detection elements 321, the two second strain detection elements 341, the two tensile detection elements 361, and the two torque detection elements 381 of each load detection module 30 via a flexible circuit board and wiring. The controller 572 receives the first detection signal V of each load detection module 30 via the analog-to-digital converter 571. S1 , the second detection signal V S2 , the third detection signal V S3 and the fourth detection signal V S4 Based on these detection signals, the light emitting element 54 is controlled via the power supply control module 53, and the light emitting element 54 is turned on to give a warning to the operator.

[0022] The wireless communication module 55 is electrically connected to the controller 572. The load detection device 100 further includes an antenna 70, which is disposed in the annular accommodating groove 12a and electrically connected to the wireless communication module 55. The antenna 70 is formed of a flexible circuit board. Thus, the controller 572 receives the first detection signal V of each load detection module 30 via the wireless communication module 55 and the antenna 70. S1 , the second detection signal V S2 , the third detection signal V S3 and the fourth detection signal V S4 The load detection signals can be transmitted to an external electronic device. This allows the operator to receive these detection signals in real time via the external electronic device, and not only can the operator grasp the load fluctuations at different positions on the main body 10 based on the detection signals of each load detection module 30, but also determine the presence or absence of vibration, tilt, or swing in the load detection device 100 from the difference in detection signals between the load detection modules 30. This allows the cutting work status to be effectively monitored and analyzed.

[0023] 1 and 4, the sealing material 80 is disposed in the annular receiving groove 12a and the wiring groove 12b of the main body 10, and covers the two load detection modules 30 and the antenna 70. The sealing material 80 is an epoxy resin.

[0024] 5 and 7 , the load detection device 100 further includes a flow passage pipe 90. The flow passage pipe 90 extends along the central axis A and is disposed within the accommodation space 41 of the inner cylinder 40. One end of the flow passage pipe 90 passes through the third through-hole 40a1 and the first opening 11a and extends to the first through-hole 200a of the tool holder head 200. The other end passes through the fourth opening 41b and extends to the second through-hole 300a of the chuck 300. The flow passage pipe 90 is disposed between the first circuit board 51 and the second circuit board 52, thereby allowing the cutting fluid to be supplied to the tool 2 via the first through-hole 200a, the flow passage pipe 90, and the second through-hole 300a, and preventing the cutting fluid from directly contacting the first circuit board 51 and the second circuit board 52.

[0025] As described above, the load detection device 100 and tool holder 1 of the present invention detect the load in the direction of the first axis L1, the load in the direction of the second axis L2, the tensile force in the direction of the central axis A, and the torque applied to the tool holder 1 by the two load detection modules 30 arranged in the main body 10, and output the first detection signals V, ... S1 , the second detection signal V S2 , the third detection signal V S3 and the fourth detection signal V S4 The control module 57 receives these detection signals through the circuit board unit 50 disposed in the inner cylinder 40 and transmits them to the external electronic device via the wireless communication module 55, allowing the operator to receive these detection signals in real time with the external electronic device, and not only to determine the load fluctuations and occurrence of vibration, tilt, and swing at different positions on the main body 10, but also to effectively monitor and analyze the cutting operation status of the tool holder 1.

[0026] In addition, the plastic inner tube 40 provides a cushioning effect for the circuit board unit 50 and the battery 61, mitigating the effects of vibration caused by the circuit board unit 50 and the battery 61 coming into direct contact with the rigid main body 10, thereby extending their lifespan.

[0027] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these, and various modifications and equivalent substitutions based on the description of the present invention and the scope of the claims are also included within the technical scope of the present invention. [Explanation of symbols]

[0028] 100: Load detection device 10: Main body 11: Hollow part 11a: 1st opening 11b: 2nd opening 12: Outer surface 12a: Annular receiving groove 12b: Wiring groove 13: Insertion hole 14: 1st binding hole 15: 1st transparent hole 16: 1st wiring hole 20: Balance weight 30: Load detection module 32: First load detection unit 321: First strain sensing element 321a: First flexible base material R1, R2, R3, R4: First strain detection structure 34: Second load detection unit 341: Second strain sensing element 341a: Second flexible base material R5, R6, R7, R8: Second strain detection structure 36: Tensile detection unit 361: Tensile detection element 361a: Third flexible base material R9, R10, R11, R12: Pull detection structure 38: Torque detection unit 381: Torque detection element 381a: Fourth flexible base material R13, R14, R15, R16: Torque detection structure 40: Inner cylinder 40a: End cover 40a1: Third through hole 41: Containment space 411: First Containment Cell 412: Second Containment Cell 413: Third Containment Cell 41a: Third opening 41b: 4th opening 42: 2nd wiring hole 43:Second coupling hole 44:Second transparent hole 50: Circuit board unit 51: 1st circuit board 511: First connector 52:Second circuit board 521: Second connector 53: Power control module 54: Light-emitting element 55: Wireless communication module 56: Vibration detection module 57: Control module 571: Analog-to-Digital Converter 572: Controller 60: Battery module 61: Battery 70: Antenna 80: Sealing material 90: Flow path pipe 200: Tool holder head 200a: 1st through hole 300: Zipper 300a: 2nd through hole 1: Tool holder 2: Tools A: Central axis L1: 1st axis L2: 2nd axis V S1 : First detection signal V S2 : Second detection signal V S3 :Third detection signal VS4 : 4th detection signal V i : Input voltage

Claims

1. A load sensing device having a defined central axis, a main body having a cylindrical shape and an annular receiving groove recessed on an outer peripheral surface; two load detection modules disposed in an annular receiving groove of the body at intervals along the central axis; a sealing material disposed in the annular receiving groove of the main body so as to cover the load detection module; A load detection device in which the load detection modules include a plurality of load detection units each having two strain detection elements arranged symmetrically around the central axis, and the strain detection elements of one of the load detection modules and the strain detection elements of the other of the load detection modules are arranged correspondingly in the axial direction of the main body.

2. Further, an inner cylinder and a circuit board unit are provided, the main body has a hollow portion, the inner cylinder is disposed in the hollow portion, the inner cylinder has an accommodating space, and the circuit board unit is disposed in the accommodating space; the circuit board unit includes a control module and a wireless communication module; The load detection device according to claim 1 , wherein the control module is electrically connected to the two load detection modules and the wireless communication module, and receives at least one detection signal from each of the load detection modules and transmits it via the wireless communication module.

3. 3. The load detection device of claim 2, wherein the circuit board unit comprises a first circuit board and a second circuit board, the first circuit board being electrically connected to the second circuit board, the control module and the wireless communication module being provided on the first circuit board, and the second circuit board being provided with a power supply control module connected to a battery module and supplying power to the control module and the wireless communication module.

4. the accommodation space has a first accommodation chamber, a second accommodation chamber, and a third accommodation chamber, the first storage chamber and the third storage chamber are located on opposite sides of the second storage chamber so as to communicate with the second storage chamber; the circuit board unit is disposed in the second housing chamber, The load detection device according to claim 3 , wherein the battery module includes two batteries arranged in the first housing chamber and the third housing chamber, respectively.

5. the main body has a first light-transmitting hole, the inner cylinder has a second light-transmitting hole, and the circuit board unit has a light-emitting element; The load detection device according to claim 2 , wherein the first light-transmitting hole and the second light-transmitting hole correspond to the light-emitting element, respectively, and light from the light-emitting element is emitted through the first light-transmitting hole and the second light-transmitting hole.

6. A plurality of insertion holes are provided at one end of the main body, The load detection device according to claim 1 , further comprising a plurality of balance weights fitted into the insertion holes, respectively.

7. The load detection units of the load detection module each include a first load detection unit that detects a load in a first axis direction perpendicular to the central axis, and a second load detection unit that detects a load in a second axis direction perpendicular to the central axis and the first axis, 2. The load detection device of claim 1, wherein the two strain detection elements of the first load detection unit are two first strain detection elements arranged symmetrically along the first axis, and the two strain detection elements of the second load detection unit are two second strain detection elements arranged symmetrically along the second axis.

8. each of the first strain detection elements includes two first strain detection structures, and the first load detection unit forms a first Wheatstone bridge having a first arm and a second arm by electrically connecting the two first strain detection structures of the first strain detection elements; 8. The load detection device of claim 7, wherein in each of the load detection modules, the two first strain detection structures in one of the first strain detection elements are respectively arranged on the upper arm of the first arm and the lower arm of the second arm of the first Wheatstone bridge, and the two first strain detection structures in the other of the first strain detection elements are respectively arranged on the lower arm of the first arm and the upper arm of the second arm of the first Wheatstone bridge.

9. 9. The load detection device of claim 8, wherein each of the second strain detection elements includes two second strain detection structures, and in each of the load detection modules, the second strain detection structures of the two second strain detection elements are electrically connected, so that each of the second load detection units forms a second Wheatstone bridge.

10. The load detection units of the load detection module each include a pull detection unit; 2. The load detection device according to claim 1, wherein the tension detection unit includes, as the strain detection elements, two tension detection elements arranged in an annular accommodating groove of the main body symmetrically about the central axis.

11. The load detection units of the load detection module each include a torque detection unit; 2. The load detection device according to claim 1, wherein the torque detection unit includes, as the strain detection elements, two torque detection elements arranged in an annular accommodating groove of the main body symmetrically about the central axis.

12. The load detection device according to claim 2 , further comprising an antenna disposed in the annular accommodating groove and electrically connected to the wireless communication module, the antenna being covered with the sealing material.

13. The load detection device according to claim 2 , wherein the main body has at least one first coupling hole, and the inner cylinder has at least one second coupling hole whose position corresponds to the at least one first coupling hole.

14. In a tool holder for connecting a machining spindle and a tool, The load detection device according to any one of claims 1 to 13, a tool holder head connected to one end of a body of the load detection device and connected to the processing spindle; a tool holder including a chuck connected to the other end of the body of the load detection device and connected to the tool.

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