Device for measuring torque and axial force

Abstract

The present invention discloses a device for measuring torque and axial force, comprising a connecting bracket and a torque measurement sensitive mechanism. The connecting bracket includes a connecting shaft, and the connecting shaft includes a first connecting portion, a second connecting portion, and a third connecting portion arranged in sequence along a first direction. At least one groove and at least two bosses are provided on the side surface of the second connecting portion, and are fixedly arranged at intervals on both sides of the groove along the first direction. A facing surface is formed on the surface of the boss away from the second connecting portion; the torque measurement sensitive mechanism is fixedly arranged on the facing surfaces of at least two bosses, the torque measurement sensitive mechanism straddles the groove along the first direction, and forms a "cliff-bridge" force amplification structure with the connecting shaft and the boss. The "cliff-bridge" force amplification structure formed by the present invention enables the strain obtained by the pasted torque measurement sensitive mechanism to increase to a greater extent, thereby improving its sensitivity.

Description

Technical Field

[0001] The present invention particularly relates to a device for measuring torque and axial force, belonging to the field of mechanical technology. Background Art

[0002] The manufacturing industry is gradually adopting fully automated systems, not only for controlling equipment but also as an effective means to meet current and future market demands. One of the main problems in the automation of machining processes is to implement a reliable and effective system for monitoring the tool state. It is reported that using these systems can increase the production level by 10 - 50%. The basic concept behind the tool state monitoring system is to obtain real-time information about the tool state during the machining operation. Any change in the tool state will generate different symptoms and information. Therefore, when monitoring these symptoms, the sensor system is very important for observing various signals generated during the machining process. These signals include torque, cutting force, vibration, acoustic emission, temperature, etc.

[0003] In the tool monitoring system, the most commonly used signals during milling and drilling processes are cutting force and torque. Currently, a bench dynamometer is often used for measurement. However, due to the high cost, commercial dynamometers are considered unsuitable for the monitoring systems in industrial processes. Therefore, an intelligent connector that is inexpensive and can meet the requirements of the tool monitoring system is needed.

[0004] CN106181578A discloses a rotary milling force sensor for measuring torque and axial force. The front end of the sensor is a standard interface for connecting the tool holder, and the rear end is a standard interface for clamping the tool. The "cage" structure in the middle is based on the curved surface formed by the bow rotating one week, and 4 pairs of symmetrically and evenly distributed slits are cut, so that the curved surface body is divided into 8 parts. Small platforms are machined on 4 of these parts, and semiconductor silicon strain gauges are pasted at the centers of the small platforms. Among them, the semiconductor strain gauges along the axial direction and perpendicular to the axial direction are connected into a Wheatstone full bridge for measuring the axial force; the semiconductor silicon strain gauges pasted along the axial directions of plus and minus 45° are connected into a Hewlett full bridge for measuring the torque received by the tool during machining. However, it must be pointed out that this sensor has the following several disadvantages. First, the overall connector of this sensor is divided into two parts and connected to the front and rear ends of the sensor respectively, which will reduce the natural frequency of the connector and greatly reduce the stiffness of the connector. Second, the structure of this sensor is complex, not very practical, and does not have good commercial value. Third, the circuit is complex and the number of sensitive units is too large. Fourth, the sensitive unit used in this sensor is a strain gauge. However, the strain gauge is a wired component, and as a sensitive unit, it has disadvantages such as low accuracy, slow measurement speed, and low dynamic response. Summary of the Invention

[0005] The main object of the present invention is to provide a device for measuring torque and axial force, so as to overcome the deficiencies in the prior art.

[0006] To achieve the foregoing object of the invention, the technical solutions adopted by the present invention include:

[0007] An embodiment of the present invention provides a device for measuring torque and axial force, including:

[0008] A connection bracket for transmitting torque and / or axial force of a force applying mechanism to a product to be measured. And the connection bracket includes:

[0009] A connection shaft, which includes a first connection portion, a second connection portion, and a third connection portion arranged in sequence along a first direction. The first connection portion can be fixedly connected to the output shaft of the force applying mechanism, the third connection portion can be fixedly connected to the product to be measured, and at least one groove is provided on the side surface of the second connection portion;

[0010] At least two bosses are fixedly arranged at intervals along the first direction on both sides of the groove, and a facing surface is formed on the surface of the boss away from the second connection portion;

[0011] A torque measurement sensitive mechanism for measuring the torque and / or axial force signal and / or the tensile signal generated by the bending moment borne by the connection shaft. The torque measurement sensitive mechanism is fixedly arranged on the facing surfaces of at least two bosses, and the torque measurement sensitive mechanism spans the groove along the first direction and forms a "cliff-bridge" force amplification structure with the connection shaft and the bosses. The "cliff-bridge" force amplification structure can amplify the strain generated by the torque or axial force received by the connection shaft and reduce the strain generated when bearing the bending moment. The first direction is the axial direction of the connection shaft.

[0012] Compared with the prior art, the advantages of the present invention include:

[0013] 1) The device for measuring torque and axial force provided by the embodiment of the present invention integrates the torque measurement sensitive mechanism and the connection bracket, improving the anti-resonance ability of the connection bracket;

[0014] 2) The device for measuring torque and axial force provided by the embodiment of the present invention, at the stress concentration position of the connection shaft, the torque measurement sensitive mechanism is pasted across the groove by grooving and forms a "cliff-bridge" force amplification structure, so that the strain obtained by the pasted torque measurement sensitive mechanism increases to a greater extent, thereby improving its sensitivity and other characteristics;

[0015] 3) The device for measuring torque and axial force provided by the embodiment of the present invention uses the torque measurement sensitive mechanism as a "bridge", so that the torque measurement sensitive mechanism can not only directly serve as a force transmission element to improve sensitivity, but also realize the measurement of torque. Since the surface acoustic wave directly serves as the force-bearing element, the structural size can be changed to increase or decrease the force, thereby changing the overall measurement range within a large range;

[0016] 4) The device for measuring torque and axial force provided by the embodiment of the present invention. While the "cliff-bridge" force amplification structure is subjected to large strains generated by torque or axial force, it reduces the strains generated by bending moment, further improving the measurement sensitivity and also improving the measurement accuracy. Description of the Drawings

[0017] Figure 1 is a schematic structural diagram of a device for measuring torque and axial force provided in a typical embodiment of the present invention;

[0018] Figure 2 is a side view of a device for measuring torque and axial force provided in a typical embodiment of the present invention;

[0019] Figure 3 A schematic cross-sectional structural diagram of a device for measuring torque and axial force provided in a typical embodiment of the present invention;

[0020] Figure 4 A schematic structural diagram of the "cliff-bridge" force amplification structure in a typical embodiment of the present invention;

[0021] Figure 5 A schematic partial structural diagram of the connection shaft with a boss in a typical embodiment of the present invention;

[0022] Figure 6 A schematic structural diagram of the protective shell in a typical embodiment of the present invention;

[0023] Figure 7 A schematic structural diagram of the information processing mechanism in a typical embodiment of the present invention. Detailed Embodiments

[0024] In view of the deficiencies in the prior art, the inventors of this case have proposed the technical solution of the present invention through long-term research and a large number of practices. The following will further explain the technical solution, its implementation process and principles, etc.

[0025] The embodiment of the present invention provides a device for measuring torque and axial force, including,

[0026] A connection bracket for transmitting torque and / or axial force of a force application mechanism to a product to be measured. And, the connection bracket includes:

[0027] A connecting shaft, the connecting shaft includes a first connecting portion, a second connecting portion and a third connecting portion arranged in sequence along a first direction, the first connecting portion can be fixedly connected to the output shaft of the force applying mechanism, the third connecting portion can be fixedly connected to the product to be tested, and at least one groove is provided on the side surface of the second connecting portion;

[0028] At least two bosses are fixedly arranged at intervals along the first direction on both sides of the groove, and a facing surface is formed on the surface of the boss away from the second connecting portion;

[0029] A torque measurement sensitive mechanism for measuring the torque and / or axial force signal and / or tensile signal generated by bending moment borne by the connecting shaft. The torque measurement sensitive mechanism is fixedly arranged on the facing surfaces of at least two bosses, and the torque measurement sensitive mechanism spans the groove along the first direction and forms a "cliff-bridge" force amplification structure with the connecting shaft and the boss. The "cliff-bridge" force amplification structure can amplify the strain generated by the torque or axial force on the connecting shaft and reduce the strain generated when bearing the bending moment. The first direction is the axial direction of the connecting shaft.

[0030] In a specific embodiment, the groove is a continuous annular groove arranged along the circumferential direction of the connecting shaft.

[0031] In a specific embodiment, the groove is recessed from the surface of the connecting shaft along a second direction, and the depth of the groove is 0.05-0.15 times the radius of the connecting shaft, wherein the second direction is the radial direction of the connecting shaft.

[0032] In a specific embodiment, the width of the groove in the first direction is 1 / 3-1 / 2 of the size of the torque measurement sensitive mechanism in the first direction.

[0033] In a specific embodiment, the height of the boss in the second direction is 0.3-0.4 times the radius of the connecting shaft.

[0034] In a specific embodiment, the distance between adjacent two bosses in the first direction is less than the length of the torque measurement sensitive mechanism in the first direction.

[0035] In a specific embodiment, the distance between adjacent two bosses in the first direction is 1 / 3-1 / 2 of the size of the torque measurement sensitive mechanism in the first direction, and the distance is greater than the width of the groove in the first direction.

[0036] In a specific embodiment, the area of each facing surface is 1 / 4-1 / 3 of the orthographic projection area of the torque measurement sensitive mechanism. Preferably, the contact area between the torque measurement sensitive mechanism and the boss is 1 / 2-2 / 3 of its own orthographic projection area.

[0037] In a specific embodiment, the device for measuring torque and axial force includes at least two of the torque measurement sensitive mechanisms, and at least two contact surfaces are provided on each of the convex platforms. Both ends of each torque measurement sensitive mechanism are fixedly arranged on one of the contact surfaces.

[0038] In a specific embodiment, at least two of the torque measurement sensitive mechanisms are arranged in mirror symmetry.

[0039] In a specific embodiment, the areas and shapes of the radial cross-sections of the first connecting portion, the second connecting portion, and the third connecting portion are the same.

[0040] In a specific embodiment, the connecting bracket further includes a product fixing mechanism, which is fixedly connected to the third connecting portion and is used for clamping and fixing the product to be measured.

[0041] In a specific embodiment, the product fixing mechanism includes a collet and a threaded fastener. The collet is fixedly connected to the third connecting portion and has a clamping space. The threaded fastener is sleeved on the collet and is threadedly connected to the collet. By screwing the threaded fastener, the size of the clamping space of the collet can be changed.

[0042] In a specific embodiment, the connecting bracket further includes a transmission shaft, which is fixedly connected to the third connecting portion and the product fixing mechanism respectively.

[0043] In a specific embodiment, the transmission shaft is fixedly connected to the collet, and the connecting shaft, the transmission shaft, and the collet are coaxially arranged.

[0044] In a specific embodiment, the connecting bracket further includes a protective shell, which is sleeved on the connecting shaft and is fixedly connected to the connecting shaft. A receiving space is formed between the protective shell and the connecting shaft, and the convex platform and the torque measurement sensitive mechanism are encapsulated in the receiving space.

[0045] In a specific embodiment, the connecting bracket further includes a driving shaft, which is fixedly connected to the first connecting portion of the connecting shaft and is used for fixedly connecting to the output shaft of the force applying mechanism. Moreover, the diameter of the driving shaft is larger than the diameter of the connecting shaft.

[0046] In a specific embodiment, the driving shaft is coaxially arranged with the connecting shaft.

[0047] In a specific embodiment, the connecting bracket further includes a clamping shaft, which is coaxially and fixedly arranged at one end of the driving shaft.

[0048] In a specific embodiment, one end of the protective shell is fixedly connected to the connecting shaft, and the other end is fixedly connected to the clamping shaft.

[0049] In a specific embodiment, the device for measuring torque and axial force further includes: an information processing mechanism, which is arranged in the accommodation space, electrically connected to the torque measurement sensitive mechanism, and at least used to calculate the torque value according to the information collected by the torque measurement sensitive mechanism.

[0050] The technical solution, its implementation process and principle will be further explained below in conjunction with the drawings and specific implementation cases. In the following embodiments, the driving shaft, clamping shaft, connecting shaft and transmission shaft are all in a cylindrical structure as an example for illustration.

[0051] Please refer to Figures 1 - 3 , a device for measuring torque and axial force, including a connecting bracket, a torque measurement sensitive mechanism 16 and an information processing mechanism 10. The torque measurement sensitive mechanism 16 is fixedly arranged on the connecting bracket, and the torque measurement sensitive mechanism 16 is electrically connected to the information processing mechanism 10.

[0052] In this embodiment, the connecting bracket is used to be connected to the product to be measured and the force applying mechanism respectively, and transfer the torque and / or axial force of the force applying mechanism to the product to be measured, for measuring the torque and / or axial force signal and / or the tensile signal generated by the bending moment borne by the connecting shaft 4. The information processing mechanism 10 is used to receive the information collected by the torque measurement sensitive mechanism 16 and calculate the torque value therefrom.

[0053] In this embodiment, the connecting bracket includes a driving shaft 1, a clamping shaft 2, a protective shell 3, a connecting shaft 4 and a transmission shaft 5;

[0054] The driving shaft 1, the connecting shaft 4 and the transmission shaft 5 are coaxially arranged in a first direction and fixedly connected in sequence. The driving shaft 1 is fixedly connected to the driving shaft of the force applying mechanism and serves as the input of torque or axial force. The clamping shaft 2 is arranged on the driving shaft 1 and is used to fixedly connect the driving shaft 1 and the driving shaft of the force applying mechanism. The torque measurement sensitive mechanism 16 is fixedly arranged on the connecting shaft 4. The transmission shaft 5 is fixedly connected to the product to be measured and serves as the output of torque or axial force. The clamping shaft 2 is coaxially arranged on the driving shaft 1 and is used for. The protective shell 3 is respectively fixedly connected to the clamping shaft 2 and the connecting shaft 4, and an accommodation space is enclosed between the protective shell 3 and the connecting shaft 4. The torque measurement sensitive mechanism 16 is encapsulated in the accommodation space.

[0055] In this embodiment, the driving shaft 1, the clamping shaft 2, the protective shell 3, the connecting shaft 4 and the transmission shaft 5 may be integrally provided.

[0056] In this embodiment, tools such as a wrench can be clamped on the holes on the clamping shaft 2 and a torque can be applied to tightly fix the connecting bracket on the drive shaft of the force application mechanism or remove it.

[0057] In this embodiment, the connecting shaft 4 includes a first connecting portion, a second connecting portion, and a third connecting portion arranged in sequence along a first direction. The first connecting portion is fixedly connected to the driving shaft 1, the third connecting portion is fixedly connected to the transmission shaft 5, the diameter of the first connecting portion is smaller than the diameter of the driving shaft 1, and a stepped structure, which can also be understood as a diameter change structure, is formed at the connection between the first connecting portion and the driving shaft 1. This is a stress concentration position. At least one groove 7 and at least two protrusions 11 are provided on the surface of the second connecting portion. The at least two protrusions 11 are fixedly arranged at intervals along the first direction on both sides of the groove 7, and a facing surface 8 is formed on the surface of the protrusion 11 away from the second connecting portion. Both ends of the torque measurement sensitive mechanism 16 are fixedly connected to the facing surfaces on the protrusions 11 on both sides of the groove 7. Moreover, the torque measurement sensitive mechanism 16 spans across the groove 7 along the first direction and forms a "cliff-bridge" force amplification structure with the connecting shaft 4 and the protrusion 11. The "cliff-bridge" force amplification structure can amplify the strain generated by the connecting shaft 4 when subjected to torque or axial force and reduce the strain generated when bearing bending moment. Specifically, the torque measurement sensitive mechanism 16 spanning across the groove 7 can not only increase the force amplification characteristic of the "cliff-bridge" force amplification structure but also have a high bending moment resistance.

[0058] In this embodiment, the groove 7 is an annular groove continuously arranged along the circumferential direction of the connecting shaft 4. It can be understood that the groove 7 is recessed from the surface of the connecting shaft 4 along a second direction.

[0059] In this embodiment, the depth of the groove 7 is 0.05 - 0.15 times the radius of the connecting shaft 4. It is found through Ansys finite element simulation verification that at this size, the strain generated by the torque on the torque measurement sensitive mechanism will increase, and at the same time, the overall structural stiffness and natural frequency of the entire device can be ensured. The second direction is the radial direction of the connecting shaft 4.

[0060] In this embodiment, the width of the groove 7 in the first direction is 1 / 3 - 1 / 2 of the size of the torque measurement sensitive mechanism 16 in the first direction. In the first direction, the width of the groove 7 is smaller than the size (which can be understood as the length) of the torque measurement sensitive mechanism 16. The size of the fixed parts pasted on both sides of the torque measurement sensitive mechanism 16 by the groove 7 is 1 / 2 - 2 / 3 of its own size. By making the groove form a "cliff" - "bridge" structure at this width dimension, and at the same time ensuring that the strain generated by the torque is concentrated in the central area of the torque measurement sensitive mechanism 16, that is, the area corresponding to the groove 7, the sensitivity of torque measurement is improved. It is verified by Ansys finite element simulation that under such structural and dimensional settings, a relatively large strain can be ensured to be generated on the torque measurement sensitive mechanism 16 by the torsion.

[0061] In this embodiment, the boss 11 is an annular boss coaxially arranged with the connecting shaft 4. The height of the boss 11 in the second direction is 0.3 - 0.4 times the radius of the connecting shaft 4, preferably 0.35 times. Based on such a design, it can be ensured that without reducing the strain generated by the torque on the torque measurement sensitive mechanism 16, the strain generated by the bending moment on the torque measurement sensitive mechanism 16 is greatly reduced, and at the same time, the natural frequency of the overall structure of the device is ensured.

[0062] In this embodiment, the distance between two adjacent bosses 11 in the first direction is smaller than the length of the torque measurement sensitive mechanism 16 in the first direction, but larger than the width of the groove in the first direction. Preferably, the distance between two adjacent bosses 11 in the first direction is 1 / 3 - 1 / 2 of the size of the torque measurement sensitive mechanism 16 in the first direction.

[0063] In this embodiment, the boss 11 can be integrally formed with the connecting shaft 4. The groove 7 can be regarded as being arranged inside the boss 11, or it can be understood that the groove 7 is wrapped by the boss 11.

[0064] In this embodiment, the device for measuring torque and axial force may include two torque measurement sensitive mechanisms 16. Two groups of bonding surfaces are provided on the two bosses 11. Each group of bonding surfaces includes two bonding surfaces. The two bonding surfaces included in the same group of bonding surfaces are respectively arranged on two different bosses 11 along the first direction, and the two groups of bonding surfaces are mirror-symmetrically distributed. Correspondingly, the two torque measurement sensitive mechanisms 16 are also radially symmetrically arranged on the connecting shaft 4.

[0065] In this embodiment, the "bridge" in the "cliff - bridge" force amplification structure is served by the torque measurement sensitive mechanism 16, that is, the two ends of the torque measurement sensitive mechanism 16 are fixed, and the middle part is suspended. Exemplarily, the thickness of the torque measurement sensitive mechanism 16 is 0.3 - 1 mm, the width is 4 - 10 mm, and the length is 3 - 6 mm. It should be noted that the length of the torque measurement sensitive mechanism 16 is the dimension along the first direction, the width is the dimension along the circumferential direction of the connecting shaft, and the thickness is the dimension along the second direction.

[0066] In this embodiment, the area of each facing 8 is 1 / 4 - 1 / 3 of the orthographic projection area of the torque measurement sensitive mechanism 16 (this orthographic projection area refers to the orthographic projection of the torque measurement sensitive mechanism on the plane where the facing is located). Preferably, the contact area between the torque measurement sensitive mechanism 16 and the boss 11 is 1 / 2 - 2 / 3 of its own orthographic projection area. Through Ansys simulation tests, it is verified that with this size design, it can ensure that a large concentrated force can be applied to the middle area of the torque measurement sensitive mechanism 16, forming a large strain, improving the sensitivity of the overall measurement, and at the same time ensuring a stable bonding strength.

[0067] In this embodiment, the torque measurement sensitive mechanism can be a capacitive, piezoelectric, resistive or other types of sensors.

[0068] In this embodiment, the torque measurement sensitive mechanism can be fixed on the facing 8 of the boss 11 by means of pasting or the like.

[0069] In this embodiment, please refer to Figure 4 and Figure 5 , the torque measurement sensitive mechanism 16 is fixedly pasted on the boss. Looking at the whole, the torque measurement sensitive mechanism 16 is pasted across the groove on the upper and lower facings 8, that is, the two ends of the torque measurement sensitive mechanism are fixed and the middle is suspended, forming a "bridge". At the same time, it can be found that since the groove 7 is located inside the boss 11 and the boss 11 itself has a certain groove depth, the overall groove depth (that is, the depth of the groove 7 itself and the gap between the two bosses 11) is further deepened. Therefore, the characteristics of the "cliff - bridge" force amplification structure are further increased. More importantly, the boss has a strong anti - bending moment ability. So when the torque measurement sensitive mechanism 16 has a large strain due to the torque or axial force generated by the "cliff - bridge" force amplification structure, the strain caused by the bending moment is reduced. At the same time, the same torque measurement sensitive mechanism 16 is pasted on the symmetric facings, which can compensate for the bending moment and improve the overall measurement accuracy.

[0070] In this embodiment, please refer to Figure 3, a snap ring 9 is provided on the connecting shaft 4, and a snap groove 12 corresponding to the snap ring 9 is provided on the protective shell 3. The snap ring 9 of the connecting shaft 4 is correspondingly embedded in the snap groove 12 inside the protective shell 3, thereby realizing the connection between the protective shell 3 and the connecting shaft 4.

[0071] In this embodiment, the snap ring 9 may be a snap protrusion formed by a part of the connecting shaft 4 protruding outward along the second direction. Exemplarily, the snap ring 9 is an annular member coaxially arranged with the connecting shaft 4; correspondingly, the snap groove 12 is formed by a part of the protective shell 3 recessing inward along the second direction, and the snap groove 12 is an annular groove; it can be understood that the snap ring 9 may also be provided on the protective shell, and the snap groove 12 may also be provided on the connecting shaft.

[0072] In this embodiment, a limiting groove 15 is further provided on the clamping shaft 2, and a limiting boss 14 is further provided on the protective shell 3. The limiting boss 14 is embedded in the limiting groove 15, thereby realizing the connection between the protective shell 3 and the clamping shaft 2; when the protective shell 3 is installed on the connecting shaft, by embedding the limiting boss 14 in the limiting groove 15 on the clamping shaft 2, it is ensured that the protective shell 3 does not rotate relative to the connecting shaft.

[0073] In this embodiment, both the limiting boss 14 and the limiting groove 15 are annular structures. It can be understood that the limiting boss 14 may also be provided on the clamping shaft, and the limiting groove 15 may also be provided on the protective shell.

[0074] In this embodiment, in the second direction, the distance between the protective shell 3 and the connecting shaft 4 is greater than the height of the boss 11, so as to reserve an installation space for the torque measurement sensitive mechanism 16.

[0075] In this embodiment, the protective shell 3 may include a first part, a second part, and a third part that are sequentially connected and arranged. Both the first part and the third part extend along the first direction. The first part and the third part are respectively fixed to the two ends of the second part and are arranged at an angle, and the first part and the third part are arranged on the same side of the second part. The length of the first part is greater than the length of the third part, so that the overall shape of the protective shell 3 is J-shaped, wherein the first part is connected to the clamping shaft 2, and the third part is connected to the connecting shaft 4.

[0076] In this embodiment, please refer to Figure 3 and Figure 7, the information processing mechanism 10 is also disposed within the accommodation space. Specifically, the information processing mechanism 10 may be fixedly disposed on the protective case 3. Exemplarily, the information processing mechanism 10 may be fixed on the second part of the protective case 3 by an interference fit, or the information processing mechanism 10 may be fixed on the second part by pasting. Among them, the information processing mechanism 10 includes a ring-shaped circuit board, etc., which is obtained through commercial purchase.

[0077] In this embodiment, please refer to Figure 1 and Figure 3 , the connecting bracket further includes a product fixing mechanism, which is fixedly connected to the transmission shaft 5 and is used for clamping and fixing the product to be measured.

[0078] In this embodiment, the product fixing mechanism includes a collet 13 and a threaded fastener 6. The collet 13 is fixedly connected to the transmission shaft 5 and has a clamping space. The threaded fastener 6 is sleeved on the collet 13 and is threadedly connected to the collet 13. By screwing the threaded fastener 6, the size of the clamping space of the collet 13 can be changed. Exemplarily, the threaded fastener 6 may be a nut, etc. By screwing the threaded fastener, the collet 13 is tightened or opened to fix or remove the product to be measured.

[0079] In this embodiment, the product to be measured may be a tool, etc.

[0080] Specifically, when operating with the device for measuring torque and axial force, the force application mechanism inputs torque power to the connected driving shaft 1, and then through the connecting shaft 4 to the rotating shaft 5 to output the torque to the product to be measured to achieve torque transmission. A torque measurement sensitive mechanism is pasted on the connecting shaft 4 to monitor torque and axial force.

[0081] The working principle of the device for measuring torque and axial force provided by the embodiment of the present invention includes:

[0082] During use, connect the driving shaft 1 of the force application mechanism (such as a driving motor, etc.) to the driving shaft of the driving shaft 1. The transmission shaft 5 is internally connected to the collet 13 and externally connected to the threaded fastener 6. Insert the product to be measured, such as a tool, into the collet 13, and rotate the threaded fastener 6 to fix the tool;

[0083] When the drive shaft of the force application mechanism rotates, torque is input to the drive shaft 1, transmitted to the rotating shaft 5 through the connecting shaft 4, and finally output to the tool to wait for the product to be measured; when the connecting shaft 4 is subjected to torque, misalignment occurs between at least two bosses 11, so that the torque measurement sensitive mechanism pasted on the facing 8 of the boss 11 is subjected to shear stress. At the same time, due to the presence of the groove 7, a "cliff-bridge" force amplification structure is formed, which increases the shear stress. Finally, the torque measurement sensitive mechanism obtains a large shear strain and outputs a high signal. The information processing mechanism 10 is responsible for receiving the signal and finally calculating the torque value according to the relationship between the signal and the torque.

[0084] Specifically, since the connecting frame will be subjected to a certain bending moment during operation, the bending moment will affect the output frequency of the torque measurement sensitive mechanism 16, making the measurement inaccurate. However, because the connecting frame in the present invention contains bosses, it has strong bending moment resistance, and by arranging the torque measurement sensitive mechanism 16 symmetrically, the bending moment can be compensated, thus greatly reducing the influence of the bending moment and improving the overall measurement accuracy. In this embodiment, the symmetrical arrangement of the torque measurement sensitive mechanism 16 means that the torque measurement sensitive mechanism 16 is symmetrically arranged on the front and back, left and right of the overall structure of the device, similar to the symmetry of the top and bottom surfaces of a cuboid; when the connecting frame is subjected to an axial force, extrusion occurs between the bosses, so that the sensitive torque measurement sensitive mechanism containing a single surface acoustic wave resonator is subjected to normal stress and outputs a signal. According to the relationship between the signal and the force, the magnitude of the axial force can be obtained, and the protective shell can protect the torque measurement sensitive mechanism from the influence of external cutting fluid, dust, etc.

[0085] The bending moment compensation formula during the torque and axial force measurement process using the device for measuring torque and axial force provided in the embodiment of the present invention is:

[0086] When the connecting frame is subjected to torque and at the same time to bending moment, the outputs of the two symmetric torque measurement sensitive mechanisms are respectively:

[0087] f1 = f0 + f n + f m

[0088] f2 = f0 + f n - f m

[0089] f o = (f1 + f2) / 2 = f0 + f n

[0090] Among them, f1 is the output of the first torque measurement sensitive mechanism, f2 is the output of the other torque measurement sensitive mechanism symmetric to it, f0 is the initial value of the torque measurement sensitive mechanism, fn is the output generated by the torque, f m is the output generated by the bending moment, fo For the total output, the positive and negative signs represent compression and tension. As can be seen from the formula, moment compensation can be carried out by the method of summation to reduce the influence caused by the moment.

[0091] According to the mechanics of materials, the shear strain on the surface of the connecting shaft is:

[0092] ε = 16T / (πd^3K)

[0093] where K = E / (2(1 + μ)), which is a constant related to the elastic modulus E and Poisson's ratio μ of the material. Therefore, according to the output value of the torque measurement sensitive mechanism, the measured torque value can be obtained by mutual calculation with the strain value.

[0094] A device for measuring torque and axial force provided by an embodiment of the present invention amplifies the force on the connecting frame, makes a groove at the position where the cross-sectional diameter of the connecting frame changes to improve the sensitivity of the torque measurement sensitive mechanism, and makes a boss at the grooved position. The torque measurement sensitive mechanism is pasted across the groove on the milled surface of the boss, forming a "cliff-bridge" force amplification structure between the tool rest and the torque measurement sensitive mechanism. That is, the torque measurement sensitive mechanism is the "bridge", enabling the torque measurement sensitive mechanism to not only be used as a force transmission element to improve sensitivity, but also measure torque / axial force. Changing the size of the "cliff-bridge" can obtain a larger measurement range. The traditional strain gauge is only used as a measurement element and cannot be used in this structure. At the same time, since the boss has the ability to resist bending moment, the influence of the bending moment during torque measurement will be reduced. Two torque measurement sensitive mechanisms are pasted on a pair of symmetric bonding surfaces to measure torque. The influence of the bending moment is reduced through the bending moment resistance of the boss and the bending moment compensation of the symmetric structure. Another pair of symmetric bonding surfaces are pasted with torque measurement sensitive mechanisms that are sensitive to axial force and insensitive to torque to measure axial force. Similarly, the symmetric structure can obtain bending moment compensation for axial force. Such a structure makes the device of the present invention have the advantages of high measurement accuracy, high sensitivity, low cross-interference, and fast response time.

[0095] A device for measuring torque and axial force provided by an embodiment of the present invention is formed by changing the size of the connecting frame on the basis of the connecting frame. In this way, the torque measurement sensitive mechanism and the connecting frame are made into a whole. Moreover, the structure of the torque measurement sensitive mechanism part is simple and easy to process, and under the premise of ensuring stiffness, the overall sensitivity and measurement accuracy are greatly improved. Through simulation, it can be obtained that the natural frequencies of the improved connecting frame and the original connecting frame are approximately equal, which also shows that the connecting frame has good anti-resonance ability.

[0096] An apparatus for measuring torque and axial force provided by an embodiment of the present invention, at the stress concentration position of the connecting shaft, by grooving, the torque measurement sensitive mechanism is pasted across the groove to form a "cliff-bridge" force amplification structure. The connecting shaft on both sides of the upper and lower sides of the groove forms two "cliffs", and the torque measurement sensitive mechanism pasted across the groove forms a "bridge" connecting the two "cliffs". When the connecting frame is subjected to torque or axial force, the torque or axial force is transmitted through the transmission form of "cliff"-"bridge"-"cliff", so that the strain obtained by the pasted torque measurement sensitive mechanism increases to a greater extent, improving its sensitivity and other characteristics.

[0097] An apparatus for measuring torque and axial force provided by an embodiment of the present invention takes the torque measurement sensitive mechanism as a "bridge", so that the torque measurement sensitive mechanism can not only directly serve as a force transmission element to improve sensitivity, but also can measure torque. Since the surface acoustic wave directly serves as the force-bearing element, the structural size can be changed to increase or decrease the force, so that the overall measurement range can be changed within a large range.

[0098] An apparatus for measuring torque and axial force provided by an embodiment of the present invention makes a boss at the groove position of the connecting shaft, pastes the torque measurement sensitive mechanism on the boss, and the anti-bending moment ability of the boss can reduce the influence of the bending moment on the measured value. Also, because there is a certain distance between the bosses, overall, the groove is located inside the boss, and it can be found that the overall groove depth is further deepened. Therefore, the characteristics of the "cliff-bridge" force amplification structure are further increased. More importantly, the boss has a strong anti-bending moment ability. Therefore, while the torque measurement sensitive mechanism has a large strain due to the "cliff-bridge" force amplification structure under torque or axial force, the strain caused by the bending moment is reduced. The final result is that while the sensitivity is increased, the measurement accuracy is also improved.

[0099] An apparatus for measuring torque and axial force provided by an embodiment of the present invention, since the size of the torque measurement sensitive mechanism is larger than the size of the upper surface of a single boss, the pasting of the torque measurement sensitive mechanism will be pasted on at least two bosses. There is a certain distance between adjacent bosses and the groove is inside them. Therefore, the boss, the groove and the torque measurement sensitive mechanism form a "cliff-bridge" force amplification structure, and the surface acoustic wave resonator on the torque measurement sensitive mechanism is exactly located at the center of this structure. Therefore, a larger strain can be obtained, thereby improving the overall sensitivity.

[0100] In the device for measuring torque and axial force provided by an embodiment of the present invention, when the torque measurement sensitive mechanism is adhered to the convex platform, two identical torque measurement sensitive mechanisms are radially symmetrically arranged. When the connecting frame works and is affected by bending moment, the signal output by one torque measurement sensitive mechanism includes not only the signal of torque or axial force but also the tensile signal generated by the bending moment. Similarly, the signal measured by the other torque measurement sensitive mechanism includes not only the signal of torque or axial force but also the compressive signal generated by the bending moment. In this way, by adding the output signals of the two torque measurement sensitive mechanisms, the compensation of the bending moment can be obtained, further improving the measurement accuracy.

[0101] In the device for measuring torque and axial force provided by an embodiment of the present invention, the protective shell can not only protect the torque measurement sensitive mechanism on the connecting frame, but also install the annular circuit board in the protective shell. Therefore, there is no need to make structural improvements on the connecting frame for installing the annular circuit board, which can reduce costs and is easier to process.

[0102] It should be understood that the above embodiments are only used to illustrate the technical concept and features of the present invention, and the purpose is to enable those familiar with this technology to understand the content of the present invention and implement it accordingly. It cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A device for measuring torque and axial force, characterized in that, including a connecting bracket for transmitting torque and / or axial force of a force applying mechanism to a product under test, and the connecting bracket includes: a connecting shaft (4), the connecting shaft (4) includes a first connecting portion, a second connecting portion and a third connecting portion arranged in sequence along a first direction, the first connecting portion can be fixedly connected to the output shaft of the force applying mechanism, the third connecting portion can be fixedly connected to the product under test, and at least one groove (7) is arranged on the side surface of the second connecting portion; at least two bosses (11) are fixedly arranged at intervals along the first direction on both sides of the groove (7), and a facing surface (8) is formed on the surface of the boss (11) away from the second connecting portion; a torque measurement sensitive mechanism (16) for measuring the torque and / or axial force signal and / or tensile signal generated by bending moment borne by the connecting shaft (4), the torque measurement sensitive mechanism (16) is fixedly arranged on the facing surfaces (8) of at least two bosses (11), and the torque measurement sensitive mechanism (16) spans the groove (7) along the first direction and forms a "cliff-bridge" force amplification structure with the connecting shaft and the boss, and the "cliff-bridge" force amplification structure can amplify the strain generated by the torque or axial force received by the connecting shaft and reduce the strain generated when bearing bending moment, and the first direction is the axial direction of the connecting shaft (4).

2. The device for measuring torque and axial force according to claim 1, characterized in that: The groove (7) is a continuous annular groove arranged along the circumferential direction of the connecting shaft (4).

3. The device for measuring torque and axial force according to claim 1 or 2, characterized in that: The groove (7) is recessed from the surface of the connecting shaft (4) along a second direction, and the depth of the groove (7) is 0.05-0.15 times the radius of the connecting shaft (4), and the second direction is the radial direction of the connecting shaft (4).

4. The device for measuring torque and axial force according to claim 3, characterized in that: The width of the groove (7) in the first direction is 1 / 3-1 / 2 of the size of the torque measurement sensitive mechanism (16) in the first direction.

5. The device for measuring torque and axial force according to claim 4, characterized in that: The height of the boss (11) in the second direction is 0.3-0.4 times the radius of the connecting shaft (4).

6. The device for measuring torque and axial force according to claim 4, characterized in that: The distance between two adjacent bosses (11) in the first direction is less than the length of the torque measurement sensitive mechanism (16) in the first direction.

7. The device for measuring torque and axial force according to claim 6, characterized in that: The distance between two adjacent bosses (11) in the first direction is 1 / 3-1 / 2 of the size of the torque measurement sensitive mechanism (16) in the first direction, and the distance is greater than the width of the groove in the first direction.

8. The device for measuring torque and axial force according to claim 7, characterized in that: The area of each facing surface (8) is 1 / 4-1 / 3 of the orthographic projection area of the torque measurement sensitive mechanism (16).

9. The device for measuring torque and axial force according to claim 8, characterized in that: The contact area between the torque measurement sensitive mechanism (16) and the boss (11) is 1 / 2-2 / 3 of its own orthographic projection area.

10. The device for measuring torque and axial force according to claim 8, characterized in that: The device for measuring torque and axial force includes at least two torque measurement sensitive mechanisms (16), at least two facing surfaces (8) are arranged on each boss (11), and both ends of each torque measurement sensitive mechanism (16) are fixedly arranged on a facing surface (8).

11. The device for measuring torque and axial force according to claim 10, characterized in that: At least two torque measurement sensitive mechanisms (16) are arranged in mirror symmetry.

12. The device for measuring torque and axial force according to claim 1, wherein: The areas and shapes of the radial cross-sections of the first connecting portion, the second connecting portion and the third connecting portion are the same.

13. The device for measuring torque and axial force according to claim 1, characterized in that: The connecting bracket further includes a product fixing mechanism, which is fixedly connected to the third connecting portion and is used for clamping and fixing the product to be measured.

14. The device for measuring torque and axial force according to claim 13, characterized in that: The product fixing mechanism includes a collet (13) and a threaded fastener (6). The collet (13) is fixedly connected to the third connecting portion and has a clamping space. The threaded fastener (6) is sleeved on the collet (13) and is threadedly connected to the collet (13). By screwing the threaded fastener (6), the size of the clamping space of the collet (13) can be changed.

15. The device for measuring torque and axial force according to claim 14, characterized in that: The connecting bracket further includes a transmission shaft (5), which is fixedly connected to the third connecting portion and the product fixing mechanism respectively.

16. The device for measuring torque and axial force according to claim 15, characterized in that: The transmission shaft (5) is fixedly connected to the collet (13), and the connecting shaft (4), the transmission shaft (5), and the collet (13) are coaxially arranged.

17. The device for measuring torque and axial force according to claim 1, characterized in that: The connecting bracket further includes a protective shell (3), which is sleeved on the connecting shaft (4) and is fixedly connected to the connecting shaft (4). A receiving space is formed between the protective shell (3) and the connecting shaft (4). The boss (11) and the torque measurement sensitive mechanism (16) are encapsulated in the receiving space.

18. The device for measuring torque and axial force according to claim 17, characterized in that: The connecting bracket further includes a driving shaft (1), which is fixedly connected to the first connecting portion of the connecting shaft (4). The driving shaft (1) is used for being fixedly connected to the output shaft of the force applying mechanism, and the diameter of the driving shaft (1) is larger than the diameter of the connecting shaft (4).

19. The device for measuring torque and axial force according to claim 18, characterized in that: The driving shaft (1) is coaxially arranged with the connecting shaft (4).

20. The device for measuring torque and axial force according to claim 18, characterized in that: The connecting bracket further includes a clamping shaft (2), which is coaxially and fixedly arranged at one end of the driving shaft (1).

21. The device for measuring torque and axial force according to claim 20, characterized in that: One end of the protective shell (3) is fixedly connected to the connecting shaft (4), and the other end is fixedly connected to the clamping shaft (2).

22. The device for measuring torque and axial force according to claim 17, characterized in that, Further included: An information processing mechanism (10), which is arranged in the receiving space, is electrically connected to the torque measurement sensitive mechanism (16), and is at least used for calculating a torque value according to the information collected by the torque measurement sensitive mechanism (16).

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