Torque sensor for tightening machine

Abstract

A torque sensor for a tightening machine disclosed by the present invention comprises a battery, a PCB, a shell and an elastic body, one end of the elastic body is connected with the battery, the PCB is located between the battery and the elastic body, a WIFI chip is integrated on the PCB, a groove is arranged in one end of the elastic body connected with the battery, the PCB is installed in the groove, the PCB is connected with the battery, and the shell is connected with the battery. The elastic body comprises a stress table, strain beams, strain gauges and a hub, one end of the hub is connected with the battery, the other end of the hub is connected with the stress table through the four strain beams, the outer side face of each strain beam is connected with one strain gauge, the strain gauges are connected with the PCB, and the shell is arranged at the positions of the strain beams of the elastic body in a sleeving mode. The torque sensor has the advantages that wireless transmission and battery power supply are adopted, and the influence of external connection wires on the work of the tightening machine is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of torque measurement of tightening machines, and in particular to a torque sensor for tightening machines. Background Art

[0002] With the rapid development of science and technology, sensors have penetrated into various fields of industrial production, including the robotics industry, grinding industry, various friction and wear testing machines, etc., but are less used in the tightening machine industry.

[0003] This is mainly because the capping head on the tightening machine usually uses permanent magnets to achieve torque control, which has the advantage of achieving torque control without external power supply, but cannot monitor the changes in torque during the capping process in real time. Although existing torque sensors can monitor the changes in torque in real time, most of them require cables for power supply and data transmission. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the power supply and data transmission of the torque sensor need to be realized through cables, and too many external cables affect the connection between the torque sensor and the tightening machine.

[0005] In response to the above technical problems, a torque sensor for a tightening machine is proposed; this is achieved through the following technical solutions: A torque sensor for a tightening machine includes a battery, a PCB, a housing, and an elastomer. One end of the elastomer is connected to the battery, and the PCB is located between the battery and the elastomer. A Wi-Fi chip is integrated on the PCB. A groove is provided inside the end of the elastomer connected to the battery, and the PCB is installed in the groove. The PCB is connected to the battery. The elastomer includes a force-bearing platform, a strain beam, a strain gauge, and a hub. One end of the hub is connected to the battery, and the other end is connected to the force-bearing platform via four strain beams. A strain gauge is connected to the outer side of each strain beam. The strain gauge is connected to the PCB. The housing is sleeved over the strain beam of the elastomer.

[0006] The battery is installed under the elastomer and directly supplies power to the elastomer without the need for external wires, solving the problem of troublesome wiring of the tightening machine equipment. The deformation detection value of the elastomer through the strain beam and strain gauge is wirelessly transmitted through the PCB board, realizing wireless transmission of data and current.

[0007] In the preferred embodiment of the technical solution of the present invention, the battery is installed inside the battery shell, the battery shell is connected to the hub of the elastomer, a first wiring groove is opened on the battery shell, the battery wire is connected to the PCB board through the first wiring groove, and the battery directly supplies power to the elastomer through internal wiring, and no external wiring is required.

[0008] In the preferred embodiment of the technical solution of the present invention, an AD acquisition chip is also integrated on the PCB board, and the AD acquisition chip is integrated in the WIFI chip. The AD acquisition chip collects the elastomer data and transmits it wirelessly through the WIFI chip. The WIFI chip transmits the detection data of the elastomer received by the AD acquisition card, and the detection data of the elastomer received by the AD acquisition card is transmitted through the WIFI chip to realize real-time monitoring.

[0009] In the preferred embodiment of the technical solution of the present invention, a circular slot is opened in the middle of the wheel hub, and two second wiring grooves are symmetrically arranged on both sides of the circular slot on the wheel hub. The PCB board is connected to the four strain gauges through wires, and the wires pass through the second wiring grooves. No external wiring is required, thereby avoiding the external wires affecting the installation of the torque sensor on the tightening machine.

[0010] In a preferred embodiment of the technical solution of the present invention, the strain gauge is a double-grid strain gauge, each strain gauge includes two wire grids, and the eight wire grids are respectively represented by R1 to R8, and the deformation of the strain gauge is monitored by the change of the wire grids.

[0011] In a preferred embodiment of the technical solution of the present invention, the eight wires are connected by wires to form a Wheatstone bridge that reflects torque changes. Each arm of the Wheatstone bridge includes two wire grids, which come from two strain gauges respectively. The deformation of the strain gauge is detected by the Wheatstone bridge, thereby detecting the torque change of the torque sensor.

[0012] In a preferred embodiment of the technical solution of the present invention, the strain gauge is a double-grid strain gauge, and the cross-section of each strain beam is square to ensure that it can be deformed under stress.

[0013] In a preferred embodiment of the technical solution of the present invention, a thread for connecting to a screw capping head on an external tightening machine is provided at the connection between the force-bearing platform and the strain beam, so as to facilitate the installation of the entire torque sensor on the tightening machine.

[0014] In a preferred embodiment of the technical solution of the present invention, the elastic body is in a cylindrical vertical beam structure as a whole, so that the diameter of the entire torque sensor is small while ensuring that the torque sensor has a certain sensitivity and rigidity.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. In the torque sensor of the present invention, the battery is installed below the elastic body and directly supplies power to the elastic body. The torque sensor does not connect to the outside and does not require external wires. This solves the problem of cumbersome wiring of the tightening machine equipment and realizes wireless transmission of current. 2. In the torque sensor of the present invention, the deformation values ​​of the strain beam and strain gauge of the elastic body are detected by the AD acquisition card on the PCB board and wirelessly transmitted to the computer through the WIFI chip, making it more convenient to observe the torque changes of the tightening machine and realizing wireless data transmission; 3. In the torque sensor of the present invention, the elastic body forms a columnar vertical beam structure, which makes the diameter of the entire torque sensor smaller while ensuring that the torque sensor has a certain sensitivity and rigidity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 FIG2 is a schematic diagram of the three-dimensional structure of a torque sensor for a tightening machine according to the present invention; Figure 2 Shown is a schematic diagram of the exploded structure of a torque sensor for a tightening machine according to the present invention; Figure 3 FIG2 is a schematic diagram of the elastic body structure of a torque sensor for a tightening machine according to the present invention; Figure 4 FIG2 is a front view of an elastic body of a torque sensor for a tightening machine according to the present invention; Figure 5 The figure shows a torque sensor for a tightening machine according to the present invention. Figure 3 Sectional view of the AA plane; Figure 6 The figure shows a front view of the installation of a strain gauge of a torque sensor for a tightening machine according to the present invention; Figure 7 The figure shows a torque sensor for a tightening machine according to the present invention. Figure 5 Sectional view of the AA plane; Figure 8 FIG2 is a schematic diagram of a Wheatstone bridge of a torque sensor for a tightening machine according to the present invention; Figure 9 FIG2 is a cross-sectional view of a torque sensor for a tightening machine according to the present invention; Figure 10 FIG2 is a schematic diagram showing the arrangement position of strain gauge wires of a torque sensor for a tightening machine according to the present invention; Figure 11 FIG. 1 shows an equivalent stress cloud diagram calculated by ANSYS Workbench for a torque sensor for a tightening machine according to the present invention; Figure 12 Shown is a total deformation cloud diagram calculated by ANSYS Workbench of a torque sensor for a tightening machine according to the present invention.

[0017] Explanation of the accompanying symbols: 1. battery; 2. PCB board; 3. elastomer; 4. housing; 5. force-bearing platform; 6. strain beam; 7. strain gauge; 8. wheel hub; 10. first wiring groove; 11. battery housing; 12. second wiring groove; 13. first strain beam; 14. second strain beam; 15. third strain beam; 17. fourth strain beam. DETAILED DESCRIPTION

[0018] The following is a combination of the embodiments of the present invention Figures 1 to 12, the technical solutions in the embodiments of the present invention are described in detail.

[0019] like Figures 1 to 4 As shown, a torque sensor for a tightening machine includes a battery 1, a PCB board 2, a shell 4 and an elastomer 3.

[0020] like Figure 2 As shown, the battery 1 and the elastic body 3 are fixedly connected by screws, so that the torque sensor is internally powered and no external wire is required to connect to the power supply, thereby reducing the impact on the tightening work of the tightening machine.

[0021] like Figure 2 As shown, a groove is provided inside one end of the elastomer 3 connected to the battery 1, and a PCB board 2 is glued inside the groove. The PCB board 2 is connected to the battery 1 through a wire. The PCB board 2 is integrated with a WIFI chip for transmitting wireless signals and an AD acquisition chip for collecting data of the elastomer 3. The AD acquisition chip is integrated inside the WIFI chip on the PCB board 2.

[0022] like Figure 2 、 Figure 3 and Figure 9 As shown, the elastic body 3 includes a force-bearing platform 5, a strain beam 6, a strain gauge 7 and a hub 8. A battery 1 is provided at one end of the hub 8. The battery 1 is pasted inside the battery shell 11. The battery shell 11 is connected to one end of the hub 8 by screws. A first wiring groove 10 is provided on the battery shell 11. The wires of the battery 1 pass through the first wiring groove 10 and are connected to the PCB board 2, ensuring that the wires are installed neatly, reducing the wire installation space, and thus reducing the volume of the entire battery 1.

[0023] like Figure 1 and Figure 2 As shown, the battery shell 11 is a cylinder, the cross section of the PCB board 2 is a circular ring, the hub 8 of the elastomer 3 is a cylindrical shell, and the elastomer 3 is a columnar vertical beam structure.

[0024] In this embodiment, because a columnar vertical beam structure is used, a torque sensor with a smaller diameter is formed. The torque sensor has an outer dimension of φ30 mm in diameter, a height x of 75.5 mm, and a measuring range of 10 Nm. While the torque sensor has a small diameter, it is ensured to have a certain sensitivity and rigidity.

[0025] The outer surface of the battery shell 11 is provided with a charging port for the battery 1 , which can be used to charge the battery 1 when the tightening machine is not in use, thereby ensuring the normal use of the torque sensor.

[0026] The battery 1 is arranged inside the torque sensor so that the torque sensor can be internally powered and does not require an external power cord, thereby avoiding the possibility that the external power cord affects the operation of the tightening machine.

[0027] like Figure 2 and Figure 3 As shown, the PCB board 2 is arranged in a groove inside the end of the wheel hub 8 close to the battery 1, and the PCB board 2 is pasted inside the groove. The other end of the wheel hub 8 is welded to one end of the four strain beams 6, and the other ends of the four strain beams 6 are welded to the force platform 5. A strain gauge 7 is pasted in the middle position of the outer side of each strain beam 6, and the strain gauge 7 is connected to the PCB board 2.

[0028] like Figure 1 and Figure 3 As shown, in this embodiment, there are four strain beams 6 , each of which has a square cross-section. One end of the hub 8 is connected to the housing 4 through a thread, and the housing 4 is sleeved on the outside of the strain beam 6 to protect the strain beam 6 .

[0029] The PCB board 2 is connected to the four strain gauges 7 through wires. A circular slot is opened in the middle of the hub 8. Two second wiring grooves 12 are symmetrically arranged on both sides of the circular slot on the hub 8. The wires pass through the second wiring grooves 12 to prevent external wiring from affecting the installation of the torque sensor.

[0030] The AD acquisition chip on the PCB board 2 collects the resistance data of the strain gauge 7 after deformation and transmits it wirelessly to the host computer through the WIFI chip.

[0031] PCB board 2 also has the function of setting the acquisition threshold. When the torque is lower than the threshold, no data is collected. The default value of the threshold is 0.5Nm. That is, when the torque value applied to the torque sensor is lower than 0.5Nm, PCB board 2 does not collect data or generate data. At this time, the WIFI chip is in a dormant state, which can reduce the power consumption of the torque sensor and improve the endurance of the torque sensor. The torque sensor threshold can be set through the host computer software.

[0032] The bottom of the force-bearing platform 5 is connected to a capping head for clamping the object to be tightened through an external thread, which facilitates the installation of a torque sensor on the tightening machine and facilitates the torque sensor to monitor the torque of the capping head of the tightening machine in real time.

[0033] like Figure 7 and Figure 8 As shown, the strain gauge 7 is a dual-grid strain gauge. Each strain gauge 7 includes two wire grids for measuring torque. The eight wire grids are represented by R1 to R8. The four strain gauges 7 are connected by wires to form a Wheatstone bridge. Each bridge arm of the Wheatstone bridge includes a wire grid of two different strain gauges 7. The deformation of the strain gauge 7 is detected by the Wheatstone bridge, thereby detecting the torque change of the torque sensor.

[0034] like Figure 5 and Figure 8As shown, in this embodiment, the four strain beams 6 are marked as a first strain beam 13, a second strain beam 14, a third strain beam 15 and a fourth strain beam 17, respectively. The wire grids of the strain gauges 7 on the four strain beams 6 are respectively: the two wire grids of the strain gauge 7 of the first strain beam 13 are R1 and R2, the two wire grids of the strain gauge 7 of the second strain beam 14 are R3 and R4, the two wire grids of the strain gauge 7 of the third strain beam 15 are R5 and R6, and the two wire grids of the strain gauge 7 of the fourth strain beam 17 are R7 and R8.

[0035] There are four positioning marks b, f, d and h on the strain gauge 7, where positioning marks b and f are positioning center lines, and positioning marks d and h are positioning lines of the wire grid, which facilitate the determination of the installation position of the strain gauge 7. In this embodiment, the two wire grids on the strain gauge 7 are defined as wire grid i and wire grid j. Wire grid i and wire grid j are distributed at 90° on both sides of the center line of the strain gauge 7 and pass through the positioning marks. The welding points of wire grid i are a and g, and the welding points of wire grid j are c and e, ensuring the stability of wire grid i and wire grid j as resistor connections in the entire Wheatstone bridge.

[0036] The wire grids in the strain gauge 7 on the first strain beam 13 are R1 and R2, the wire grids in the strain gauge 7 on the second strain beam 14 are R3 and R4, the wire grids in the strain gauge 7 on the third strain beam 15 are R5 and R6, and the wire grids in the strain gauge 7 on the fourth strain beam 17 are R7 and R8.

[0037] In this embodiment, the computer receives the WIFI chip signal through a receiver. The computer receiver is an existing technology and has been put into use in life.

[0038] like Figure 11-12 As shown, in this embodiment, the torque sensor for the tightening machine is simulated using ANSYS Workbench. The finite element analysis of the elastomer 3 is performed using ANSYS Workbench. The stiffness is 1.2965x104Nm / rad, and the maximum equivalent stress is 165.32Mpa, which is much smaller than the yield strength (1200Mpa) of the elastomer material (40CrnimoA). The overload capacity exceeds 500%.

[0039] like Figure 11 As shown in the figure, the simulation process of the torque sensor for the tightening machine through ANSYS Workbench is as follows: First, set the boundary conditions: apply a torque of 10 Nm to the load-bearing platform 5.

[0040] Then perform calculation: submit the calculation model to Workbench software for calculation.

[0041] Finally, check the calculation results: the maximum equivalent stress of the sensor is calculated to be 165.32Mpa, and the stiffness is 1.2965x104Nm / rad.

[0042] The sensor is installed on the capping head device, and the strain gauges 7 are formed into a Wheatstone bridge using wires to ensure that the deformation of the four strain beams 6 can be detected. The torque change is reflected through the Wheatstone bridge, thereby improving the accuracy of the sensor detection data. The sensor is installed in the capping head, and a fixed torque is applied to the capping head through a servo motor. The fixed torque is transmitted to the sensor through the capping head. The force on the sensor causes the sensor strain beam 6 to deform, causing the strain gauge 7 to deform accordingly. The voltage value at the output end of the Wheatstone bridge is calculated based on the resistance value of the strain gauge 7 after deformation.

[0043] The voltage value at the output of the Wheatstone bridge is calculated as follows:

[0044] ——Indicates the output voltage value in the Fx direction when Fx is fully loaded; ——Indicates the sensitivity coefficient of the strain gauge. The average value is usually taken when calculating, and k=2; ——represent the strain measured in the R1~R8 patch area respectively; ——Indicates the excitation voltage of the bridge circuit, here we take .

[0045] ; The detection value of the sensor is transmitted to the computer through the wireless PCB board 2. By attaching the strain gauge 7 to the sensor to form a Wheatstone bridge, the sensitivity and stiffness of the sensor can be detected at the same time, and the torque change of the tightening machine can be more conveniently observed through the computer.

[0046] like Figure 12 As shown in the figure, when a torque of 10 Nm is applied to the sensor, the first strain beam 13, the second strain beam 14, the third strain beam 15, and the fourth strain beam 17 are deformed. R1, R3, R5, and R7 are subjected to tensile strain, and R2, R4, R6, and R8 are subjected to compressive strain. Static simulation of elastic body 3 is performed using Workbench software. After simulation calculation, the equivalent stress of elastic body 3 is 165.32 MPa and the deformation is 0.011577 mm. The strain in the R1 patch area is , the strain in the R2 patch area is , the strain in the R3 patch area is , the strain in the R4 patch area is , the strain in the R5 patch area is , the strain in the R6 patch area is , the strain in the R7 patch area is , the strain in the R8 patch area is , will be composed as Figure 8 In the Wheatstone bridge, then:

[0047] Then the sensitivity is: .

[0048] Therefore, the sensor of the present invention has high accuracy, rigidity and sensitivity.

[0049] The above embodiments are only for illustrating the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A torque sensor for a tightening machine, characterized in that: The invention comprises a battery (1), a PCB (2), a housing (4) and an elastic body (3), wherein one end of the elastic body (3) is connected to the battery (1), the PCB (2) is located between the battery (1) and the elastic body (3), a WIFI chip is integrated on the PCB (2), a groove is provided inside the end of the elastic body (3) connected to the battery (1), the PCB (2) is installed in the groove, and the PCB (2) is connected to the battery (1); The elastic body (3) comprises a force-bearing platform (5), a strain beam (6), a strain gauge (7) and a wheel hub (8). One end of the wheel hub (8) is connected to the battery (1), and the other end is connected to the force-bearing platform (5) via four strain beams (6). Each strain beam (6) is connected to a strain gauge (7) on its outer side. The strain gauge (7) is connected to the PCB (2). The housing (4) is sleeved on the position of the strain beam (6) of the elastic body (3).

2. The torque sensor for a tightening machine according to claim 1, characterized in that: The battery (1) is installed inside the battery (1) shell, and the battery (1) shell is connected to the hub (8) of the elastic body (3). A first wiring groove (10) is opened on the battery (1) shell, and the wire of the battery (1) is connected to the PCB board (2) through the first wiring groove (10).

3. The torque sensor for a tightening machine according to claim 2, characterized in that: An AD acquisition chip is also integrated on the PCB board (2), and the AD acquisition chip is integrated in the WIFI chip. The AD acquisition chip collects data of the elastomer (3) and transmits it wirelessly via the WIFI chip.

4. The torque sensor for a tightening machine according to claim 1, wherein: A circular slot is provided in the middle of the wheel hub (8), and two second wiring slots (12) are symmetrically provided on both sides of the circular slot on the wheel hub (8). The PCB board (2) and the four strain gauges (7) are connected via wires, and the wires pass through the second wiring slots (12).

5. The torque sensor for a tightening machine according to claim 1, characterized in that: The strain gauge (7) is a double-grid strain gauge (7), each strain gauge (7) includes two wire grids, and the eight wire grids are respectively represented by R1 to R8.

6. The torque sensor for a tightening machine according to claim 1, characterized in that: The eight wires are connected by wires to form a Wheatstone bridge that reflects the change in torque. Each arm of the Wheatstone bridge includes two wire grids, and the two wire grids come from two strain gauges (7).

7. The torque sensor for a tightening machine according to claim 7, characterized in that: Each strain beam (6) has a square cross section.

8. The torque sensor for a tightening machine according to claim 1, characterized in that: A thread for connecting to a capping head on an external tightening machine is provided at the connection between the force-bearing platform (5) and the strain beam (6).

9. The torque sensor for a tightening machine according to claim 1, characterized in that: The elastic body (3) is in the form of a cylindrical vertical beam structure as a whole.

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