A micro-torque sensor manufacturing method

Abstract

The application relates to the technical field of sensor production, in particular to a micro-range torque sensor manufacturing method, which comprises the following steps: Step 1, elastic body fine milling; Step 2, elastic body wire cutting; Step 3, elastic body cleaning; and Step 4, sensor manufacturing. The micro-range torque sensor manufacturing method can avoid the bending deformation of the cross double straight beams of the elastic body caused by stress in the machining process through the form of tooling assistance, so that the measurement accuracy of the sensor is improved.

Description

Technical Field

[0001] This invention relates to the field of sensor manufacturing technology, specifically a method for manufacturing a micro-range torque sensor. Background Technology

[0002] Torque sensors are used to detect torsional torque on various rotating or non-rotating mechanical components. They are widely used in the optimization of power drive systems, quality inspection, operational condition monitoring, and intelligent control of various mechanical equipment. For certain industries, such as watchmaking and robotics, there are specific requirements for the range of torque sensors, necessitating micro-range (0.03 N·m - 0.2 N·m) torque sensors to meet production and testing needs.

[0003] Figure 1 This is a schematic diagram of the external structure of a micro-range torque sensor, as shown below. Figure 1 As shown, the micro-range torque sensor has a disc-shaped structure, including an outer flange 1, a cross double straight beam 2, and an inner flange 3. The outer flange 1 and the inner flange 3 are connected by a connecting beam. The cross double straight beam 2 is located between two adjacent connecting beams. The cross double straight beam 2 and the connecting beams divide the area between the outer flange 1 and the inner flange 3 into 8 hollow areas. These hollow areas are precision milled during production. The outer flange 1 has an outer diameter of 70mm. To meet the application requirements of narrow spaces, the sensor height is only 12mm. The product is thin and small in size, which increases the difficulty of processing the sample.

[0004] The core of the micro-range torque sensor lies in the elastomer, which adopts a cross-shaped double straight beam 2 structure. The elastomer is a machined part and needs to be manufactured through processes such as roughing, finishing, wire cutting, and surface treatment. The cross-shaped double straight beam 2 connects the outer flange 1 and the inner flange 3. When the outer flange 1 and the inner flange 3 are subjected to torsion, the cross-shaped double straight beam 2 deforms to measure the torque value.

[0005] The following technical challenges still exist in the manufacturing and processing of existing micro-range torque sensors:

[0006] 1. Bending deformation of the sensor's cross-shaped double straight beam

[0007] The sensor design achieves different torque sensor ranges (0.03Nm-0.2Nm) by controlling the thickness and width of the beam. Within this range, the thickness of the cross-shaped double straight beam 2 is only 0.4mm-0.75mm. Existing machining technology can meet the dimensional requirements through precision machining, but the cross-shaped double straight beam 2 is too thin and narrow, which will cause bending deformation of the beam during machining, and even breakage. Since the cross-shaped double straight beam 2 is the core strain zone of the sensor, bending deformation will result in poor sensor accuracy, and beam breakage will render the workpiece unusable.

[0008] 2. The inner flange is biased to one side.

[0009] Because the sensor has a very small range, a foolproof design was implemented to protect against overload. This is achieved by cutting grooves at the outer ends of the four beams of the inner flange 3 and the inner end of the outer flange 1. This design can prevent sensor damage caused by improper operation during installation or application. However, during normal cutting, the workpiece will also be affected by stress, resulting in the four beams of the inner flange 3 being biased to one side. In fact, the cross double straight beam 2 of the elastic body has bent and deformed. This situation will cause poor sensor accuracy, inconsistent sensitivity between positive and negative torsion, and even jamming before the positive torsion (or negative torsion) reaches the range.

[0010] To address the aforementioned issues, the fabrication process of the micro-range torque sensor has been optimized to prevent bending deformation of the elastic cross-shaped double straight beam under stress. Therefore, we propose a fabrication method for a micro-range torque sensor. Summary of the Invention

[0011] The purpose of this invention is to provide a method for manufacturing a micro-range torque sensor to solve the problems mentioned in the background art.

[0012] To achieve the above objectives, the present invention provides the following technical solution:

[0013] A method for manufacturing a micro-range torque sensor, the method comprising the following steps:

[0014] Step 1, Precision milling of the elastomer

[0015] During the machining of the cross-shaped double straight beam elastomer, eight identical precision milling operations need to be completed. Tool B is coated with lubricating oil and placed on the bottom of the cross-shaped double straight beam. After the precision milling operation of one shape is completed, the waste chips are blown away with an air gun, and tool A is inserted into the precision milled shape. The colloid is poured into the shape and allowed to cool and solidify before the precision milling operation of the next shape is performed. After the shape is completed, tool A and colloid are used in the same way, and so on, until eight shapes are completed.

[0016] Step 2, elastomeric wire cutting

[0017] Remove the elastomer with the completed cross-shaped double straight beam from the milling machine, remove the fixture B placed at the bottom, while retain fixture A and the elastomer and install them together on the wire EDM machine to cut 8 vertical slits and 4 horizontal slits. After completing the cutting of one vertical slit and the connected horizontal slit, insert fixture C to cut the vertical slit on the opposite side. Insert fixture C in the same way, and so on, until all cutting processes are completed.

[0018] Step 3, Elastomer Cleaning

[0019] After the elastomer is processed, it is placed in a container and immersed in hot water above 60°C. At this time, the colloid gradually melts. The elastomer is then removed, tooling A and tooling C are removed, and the elastomer is cleaned and dried.

[0020] Step 4, Sensor fabrication

[0021] The machined elastomer is assembled with strain gauge patches and bridges to form a sensor with a range of 0.03 N·m, and then calibrated. The outer flange of the sensor is fixed to a vertical surface with bolts, and the calibration fixture is installed on the inner flange with bolts. The stress value is calculated based on the sensor range and the torque between the force application point and the center point of the sensor. The stress value is applied by weights. The range is divided into 6 equal parts, and the forward and retrace measurements are repeated 3 times.

[0022] Preferably, the tooling A is made of aluminum alloy with a thickness of 0.3mm, and the hollow shape between the cross double straight beam and the inner and outer flange connecting beams corresponds to the shape of the tooling A;

[0023] The tooling B is made of aluminum alloy with a thickness of 0.5mm, is disc-shaped, and has an outer diameter greater than 70mm.

[0024] The tooling C is made of aluminum alloy with a thickness of 0.6 mm and is in sheet form;

[0025] The colloid is a mixture of paraffin and gasoline.

[0026] Preferably, paraffin wax and gasoline are mixed in a mass ratio of 17:20. The container containing the mixture is then immersed in hot water at a temperature above 60°C. The paraffin wax dissolves in the gasoline, and after stirring, it forms a colloid. When the temperature cools, the colloid solidifies.

[0027] Compared with the prior art, the beneficial effects of the present invention are: the method for manufacturing a micro-range torque sensor uses tooling assistance during machining to avoid bending deformation of the cross-shaped double straight beam of the elastomer under stress, thereby improving the measurement accuracy of the sensor. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the external structure of a micro-range torque sensor in the prior art;

[0029] Figure 2 This is a schematic diagram of the external structure of the auxiliary tooling A of the present invention;

[0030] Figure 3 This is a schematic diagram illustrating the optimized manufacturing process of the crossbeam for the micro-range torque sensor of the present invention.

[0031] Figure 4 This is a schematic diagram illustrating the optimized design process for the micro-range torque sensor of the present invention to prevent mistaken design.

[0032] Figure 5 The image shows a comparison of the appearance of the micro-range torque sensor processed by the process of this invention and conventional processes.

[0033] In the diagram: 1. Outer flange; 2. Cross double straight beam; 3. Inner flange. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In the description of this invention, it should be understood that the terms "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0036] In the description of this patent, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this patent according to the specific circumstances.

[0037] With the advancement of the automation industry, the requirements for torque sensing control applications and accuracy are becoming increasingly stringent. If conventional machining processes are used to manufacture micro-range torque sensors, there will be issues such as the elastic cross double straight beam bending and deforming under stress during the machining process, which reduces the measurement accuracy of the sensor.

[0038] To address the aforementioned issues, process optimization was implemented, employing tooling assistance during machining to prevent the elastic cross-shaped double straight beam from bending and deforming under stress.

[0039] The auxiliary tooling mainly includes tooling A, tooling B, colloid, and tooling C; tooling A, tooling B, and colloid assist in the finishing stage; tooling C assists in the wire EDM stage.

[0040] Tooling A is made of aluminum alloy with a thickness of 0.3mm. Figure 2As shown, the shape resembles the precision-milled part of the sensor, so that the hollow shape between the cross double straight beam and the inner and outer flange connecting beams corresponds to the shape of the tooling A.

[0041] Tooling B is made of aluminum alloy, 0.5mm thick, and is disc-shaped with an outer diameter slightly larger than 70mm. It is used to cover the bottom of the sensor.

[0042] Tooling C is made of aluminum alloy with a thickness of 0.6mm (the thickness of the tooling is consistent with the gap between the outer end of the inner flange beam and the inner end of the outer flange groove), and it is in sheet form.

[0043] The colloid is a mixture of paraffin and gasoline. The fixed paraffin and gasoline are mixed in a mass ratio of 17:20. The container containing the mixture is immersed in hot water above 60°C. The paraffin dissolves in the gasoline. After stirring, it forms a colloid. When the temperature cools, the mixture becomes solid.

[0044] The elastomer of the micro-range torque sensor is made of hard aluminum alloy, which is more suitable for small-range deformation measurement. After processing, the elastomer is subjected to anodizing and sandblasting treatment for appearance finishing and protection.

[0045] Specifically, we provide a method for manufacturing a micro-range torque sensor, the method comprising the following steps:

[0046] Step 1, Precision milling of the elastomer

[0047] Step 11: During the machining of the cross-shaped double straight beam elastomer, eight identical precision milling operations need to be completed. Apply lubricant to fixture B and place it on the bottom of the cross-shaped double straight beam. After completing the precision milling operation of one shape, blow away the debris with an air gun, and then fit fixture A into the milled shape. Pour the elastomer into the shape and allow it to cool and solidify before performing the precision milling operation on the next shape. After completing this shape, use fixture A and the elastomer in the same way, and so on, until all eight shapes are completed. Figure 2 and Figure 3 As shown, the auxiliary tooling A used in this process has a hollow design. This workpiece is easy to shape and fits better with the elastomer. In order to increase the support strength, it is used in conjunction with the colloid. This application method provides good support for the cross double straight beam. The workpiece is not affected by stress during processing and the cross double straight beam will not bend or deform.

[0048] Step 2, elastomeric wire cutting

[0049] The error-proof design of the elastomer needs to be implemented through wire EDM. The elastomer, with its cross-shaped double straight beam, is removed from the milling machine. Fixture B, which is placed underneath, is removed, while fixture A and the elastomer remain and are installed together on the wire EDM machine. Eight vertical slits and four horizontal slits are cut. After one vertical slit and its adjacent horizontal slit are cut, fixture C is inserted to cut the opposite vertical slit. Fixture C is then inserted again, and this process is repeated until all cutting steps are completed. Figure 4 As shown. With the support of the existing tooling A and the colloid, tooling C is inserted to provide better reinforcement and prevent the inner flange beam from shifting.

[0050] Step 3, Elastomer Cleaning

[0051] After the elastomer is processed, it is placed in a container and immersed in hot water above 60℃. The colloid gradually melts. The elastomer is then removed, and tooling A and tooling C are taken off. The elastomer is then cleaned and dried. Comparison images of the elastomer's appearance after conventional and optimized machining processes are shown below. Figure 5 As shown, the sensor cross beam produced by the optimized process did not exhibit bending deformation, and the inner flange beam was located in the middle of the slot.

[0052] Step 4, Sensor fabrication

[0053] The machined elastomer is assembled with strain gauge patches and bridges to form a sensor with a range of 0.03 N·m, and then calibrated. The outer flange of the sensor is fixed to a vertical surface with bolts, and the calibration fixture is installed on the inner flange with bolts. The stress value is calculated based on the sensor range and the torque between the applied force point and the center point of the sensor (F = Mz / Sz, where F is the stress value, Mz is the torque centered on the Z-axis, and Sz is the lever arm of the applied force to the Z-axis). The stress value is applied by weights, the range is divided into 6 equal parts, and the forward and retrace measurements are repeated 3 times.

[0054] Table 1 shows the machining process for micro-range torque sensors (positive torque).

[0055]

[0056] Table 2 shows the machining processes for micro-range torque sensors (reverse torque).

[0057]

[0058] The workpiece exhibits significant differences in sensitivity and accuracy between forward and reverse torsion, with poor linearity in reverse torsion.

[0059] Table 3 shows the optimized machining process for micro-range torque sensors (positive torque).

[0060]

[0061] Table 4. Optimized machining process for micro-range torque sensors (reverse torque).

[0062]

[0063] The optimized process produces a micro-range torque sensor with consistent forward and reverse torque sensitivities, and its linearity, hysteresis, and repeatability are all within 0.1%FS, with sensor accuracy reaching 0.1%.

[0064] As can be seen from the above, this method for manufacturing a micro-range torque sensor uses tooling assistance during machining to prevent the cross-shaped double straight beam of the elastic body from bending and deforming under stress, thereby improving the measurement accuracy of the sensor.

[0065] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing a micro-range torque sensor, characterized in that, The method includes the following steps: Step 1, Precision milling of the elastomer During the machining of the cross-shaped double straight beam elastomer, eight identical precision milling operations need to be completed. Tool B is coated with lubricating oil and placed on the bottom of the cross-shaped double straight beam. After the precision milling operation of one shape is completed, the waste chips are blown away with an air gun, and tool A is inserted into the precision milled shape. The colloid is poured into the shape and allowed to cool and solidify before the precision milling operation of the next shape is performed. After the shape is completed, tool A and colloid are used in the same way, and so on, until eight shapes are completed. Step 2, elastomeric wire cutting Remove the elastomer with the completed cross-shaped double straight beam from the milling machine, remove the fixture B placed at the bottom, while retain fixture A and the elastomer and install them together on the wire cutting machine to cut 8 vertical slits and 4 horizontal slits. After completing the cutting of one vertical slit and the connected horizontal slit, insert fixture C to cut the vertical slit on the opposite side. Insert fixture C in the same way, and so on, until all cutting processes are completed. Step 3, Elastomer Cleaning After the elastomer is processed, it is placed in a container and immersed in hot water above 60°C. At this time, the colloid gradually melts. The elastomer is then removed, tooling A and tooling C are removed, and the elastomer is cleaned and dried. Step 4, Sensor fabrication The machined elastomer is assembled with strain gauge patches and bridges to form a sensor with a range of 0.03 N·m, and then calibrated. The outer flange of the sensor is fixed to a vertical surface with bolts, and the calibration fixture is installed on the inner flange with bolts. The stress value is calculated based on the sensor range and the torque between the force application point and the center point of the sensor. The stress value is applied by weights. The range is divided into 6 equal parts, and the forward and retrace measurements are repeated 3 times.

2. The microscale torque sensor fabrication method of claim 1, wherein: The tooling A is made of aluminum alloy with a thickness of 0.3mm. The hollow shape between the cross double straight beam and the inner and outer flange connecting beams corresponds to the shape of the tooling A. The tooling B is made of aluminum alloy with a thickness of 0.5mm, is disc-shaped, and has an outer diameter greater than 70mm. The tooling C is made of aluminum alloy with a thickness of 0.6 mm and is in sheet form; The colloid is a mixture of paraffin and gasoline.

3. The method for manufacturing a micro-range torque sensor according to claim 2, characterized in that: Paraffin wax and gasoline are mixed in a mass ratio of 17:

20. The container containing the mixture is then immersed in hot water above 60°C. The paraffin wax dissolves in the gasoline, and after stirring, it forms a colloid. When the temperature cools, the colloid solidifies.

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