Auxiliary centering device based on hole edge chamfering and centering method based on hole edge chamfering

Abstract

The invention relates to an auxiliary centering device based on a hole edge chamfer and a centering method based on the hole edge chamfer, the strain value of a protrusion is measured through a detection piece, and the acting force borne by the protrusion can be determined; further, the pre-pressing depth of the bulge and the coordinate of the bulge can be determined; therefore, the coordinates of the central axis of the head are calculated. And based on the coordinates of the central axis of the head and the coordinates of the central axis of the workpiece, the offset compensation amount is determined, so that the workpiece is compensated, the coordinates of the central axis of the workpiece coincide with the coordinates of the central axis of the head, and alignment of the assembly hole and the auxiliary centering device is achieved. Therefore, the assembly hole is aligned with the cutter handle connected with the auxiliary centering device, namely, the center of the assembly hole of the workpiece and the center of the cutter handle are centered at high precision, the centering precision of a machining device subsequently connected with the cutter handle and the assembly hole is guaranteed, the strengthening uniformity of the surface of the assembly hole is guaranteed, and the strengthening quality and the fatigue performance of the workpiece with the hole are guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mechanical manufacturing, in particular to an auxiliary centering device based on hole edge chamfer and a centering method based on hole edge chamfer. BACKGROUND

[0002] In the field of mechanical manufacturing, in order to meet the assembly requirements, many hole workpieces are designed with assembly holes. In order to reduce stress concentration and facilitate subsequent assembly operation, the edge of the assembly hole (referred to as hole edge) is often chamfered.

[0003] In order to reduce the fatigue cracks of hole edge chamfer and prolong the service life of hole workpiece, a machining device is usually connected through a tool holder connected to the main shaft to strengthen the assembly hole. Before strengthening the assembly hole, the workpiece needs to be clamped to the workbench through a clamping device.

[0004] During clamping, due to the accuracy of the clamping device and other factors, the centering deviation problem often occurs, that is, the assembly hole is not aligned with the machining device, which will lead to uneven strengthening of the surface of the assembly hole, affecting the strengthening quality, and further seriously affecting the fatigue performance of the hole workpiece. SUMMARY

[0005] Therefore, it is necessary to provide an auxiliary centering device based on hole edge chamfer and a centering method based on hole edge chamfer to solve the centering deviation problem of the hole workpiece clamped to the workbench.

[0006] An auxiliary centering device based on hole edge chamfer, the auxiliary centering device based on hole edge chamfer comprises:

[0007] a support for connecting with a tool holder;

[0008] a rod connected to the tool holder;

[0009] a head connected to one end of the rod away from the support;

[0010] a plurality of protrusions connected to the head and distributed along the circumference of the head;

[0011] a plurality of detection pieces connected to the rod and distributed along the circumference of the rod; each detection piece is arranged one-to-one corresponding to one protrusion; the detection piece is used to detect the strain signal of the corresponding protrusion.

[0012] In one embodiment, the plurality of detection pieces are uniformly arranged, and the detection pieces are located at one end of the rod away from the head.

[0013] In one embodiment, the projection of the protrusion in the horizontal plane is collinear with the projection of the detection piece in the horizontal plane.

[0014] In one of the embodiments, the plurality of protrusions are detachably connected to the head.

[0015] In one of the embodiments, the auxiliary centering device further comprises a signal emitting device connected to the support, the signal emitting device being in communication connection with the detecting member.

[0016] The auxiliary centering device further comprises a signal receiving device, the signal receiving device being in communication connection with the signal emitting device.

[0017] A centering method based on hole edge chamfer, based on the auxiliary centering device based on hole edge chamfer as described above, the centering method comprising:

[0018] Controlling the auxiliary centering device to move downward along the vertical direction so that the protrusions abut against the hole edge chamfer;

[0019] Obtaining the strain signals of the detecting members;

[0020] Calculating the coordinates of the center axis of the head;

[0021] Based on the coordinates of the center axis of the head and the coordinates of the center axis of the workpiece, determining the offset compensation amount;

[0022] Repeating the controlling the workbench to move along the horizontal direction and obtaining the strain signal change values of the detecting members until the strain signal change values of the detecting members are all less than a preset value.

[0023] In one of the embodiments, the method of calculating the coordinates of the center axis of the head comprises:

[0024] Establishing the relationship between the strain value and the acting force to calculate the acting force received by the plurality of protrusions;

[0025] Establishing the relationship between the acting force and the pre-pressing depth to calculate the pre-pressing depth of the plurality of protrusions;

[0026] According to the pre-pressing depth of the plurality of protrusions, calculating the coordinates of the protrusions;

[0027] According to the coordinates of the plurality of protrusions, calculating the coordinates of the center axis of the head.

[0028] In one of the embodiments, the method of establishing the relationship between the strain value and the acting force to calculate the acting force received by the plurality of protrusions comprises:

[0029] Obtaining the first compressive strain, the second compressive strain and the tensile strain of each protrusion;

[0030] Obtaining the strain value of each protrusion, the strain value being the sum of the first compressive strain, the second compressive strain and the tensile strain;

[0031] Based on the strain value, a vertical force on the protrusion is calculated;

[0032] Based on the vertical force, a horizontal force on the protrusion is calculated.

[0033] In one embodiment, the method for establishing a relationship between the force and the pre-pressing depth to calculate the pre-pressing depth of the protrusions comprises:

[0034] Based on the vertical force, a normal force on the protrusion is calculated;

[0035] A contact radius between the protrusion and the chamfer is calculated;

[0036] Based on the contact radius, a first displacement of the protrusion due to contact deformation is calculated;

[0037] A second displacement of the protrusion due to bending of the stem caused by the horizontal force is calculated;

[0038] A third displacement of the protrusion due to compression deformation of the stem caused by the vertical force is calculated;

[0039] Based on the first displacement, the second displacement and the third displacement, the pre-pressing depth of the protrusion is determined;

[0040] Based on the pre-pressing depth of the protrusion, a horizontal pre-pressing depth of the protrusion is calculated.

[0041] In one embodiment, the method for calculating the coordinates of the protrusions based on the pre-pressing depth of the protrusions comprises:

[0042] Based on the position angle of the protrusion, a position vector of the protrusion is calculated;

[0043] Based on the center coordinates of the chamfer and the chamfer radius, coordinates of a point on the chamfer are calculated;

[0044] Based on the coordinates of the point on the chamfer, based on the equivalent radius of the head, based on the horizontal pre-pressing depth of the protrusion and based on the position vector of the protrusion, the coordinates of the protrusion are calculated.

[0045] The auxiliary centering device based on the chamfer of the hole edge and the auxiliary centering method based on the chamfer of the hole edge can determine the force acting on the protrusion by measuring the strain value of the protrusion by the detection member, and further determine the pre-pressing depth of the protrusion and the coordinates of the protrusion, so as to calculate the coordinates of the center axis of the head. Based on the coordinates of the center axis of the head and the coordinates of the center axis of the workpiece, the offset compensation amount is determined, so as to compensate the workpiece, so that the coordinates of the center axis of the workpiece coincide with the coordinates of the center axis of the head, and the assembly hole and the auxiliary centering device are aligned. Further, the assembly hole and the tool shank connected with the auxiliary centering device are aligned, that is, the high-precision centering of the center of the assembly hole of the workpiece and the center of the tool shank is realized, the centering precision of the machining device connected with the tool shank in the subsequent process and the assembly hole is ensured, the uniformity of the surface of the assembly hole is ensured, and the quality of the strengthening and the fatigue performance of the workpiece with the hole are ensured. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments or example embodiments of the present application, the drawings needed to be used in the description of the embodiments or example embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0047] Figure 1 A schematic diagram of the auxiliary centering device based on the chamfer of the hole edge provided by an embodiment of the present application.

[0048] Figure 2 For Figure 1 A partial force analysis schematic diagram of the auxiliary centering device based on the chamfer of the hole edge shown in the figure.

[0049] Figure 3 For Figure 1 A simplified schematic diagram of the auxiliary centering device based on the chamfer of the hole edge shown in the figure.

[0050] Figure 4 For Figure 1 A deformation schematic diagram of the protrusion and the chamfer contact in the auxiliary centering device based on the chamfer of the hole edge shown in the figure.

[0051] Figure 5 For Figure 1 A deformation schematic diagram of the rod part and the head part in the auxiliary centering device based on the chamfer of the hole edge shown in the figure.

[0052] Figure 6 For Figure 1 A top view schematic diagram of the auxiliary centering device based on the chamfer of the hole edge shown in the figure.

[0053] Figure 7 For Figure 1 An offset compensation schematic diagram of the auxiliary centering device based on the chamfer of the hole edge shown in the figure.

[0054] Figure 8 Flow chart of the centering method provided for an embodiment of the application.

[0055] Figure 9 Comparison chart of the theoretical force and the actual force.

[0056] Figure 10 Comparison chart of the theoretical pre-pressing depth and the actual pre-pressing depth.

[0057] Reference signs: 110, bracket; 120, rod part; 130, head part; 140, protrusion; 150, detection piece; 160, compensation strain gauge; 170, power supply; 180, signal transmitting device; 190, signal receiving device; 210, tool shank; 220, transmitter. DETAILED DESCRIPTION

[0058] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in a number of different ways beyond the specific embodiments described and it is therefore contemplated to cover all such modifications as fall within the scope of the application. It is to be understood that the specific embodiments of the present application are shown by way of illustration and not as limitations.

[0059] In the description of the present application, it needs to be understood that if there are terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0060] In addition, if there are terms such as "first", "second", these terms are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implying the number of technical features indicated. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, if the term "multiple" appears, the meaning of "multiple" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0061] In the present application, unless specifically defined otherwise, if there is an appearance of the terms "installation", "connection", "connection", "fixation" and the like, these terms should be broadly interpreted. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise specifically defined. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0062] In the present application, unless specifically defined otherwise, if there is a description of the first feature "on" or "under" the second feature and the like, it means that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0063] It should be noted that if an element is referred to as "fixed to" or "provided on" another element, it can be directly on another element or there can be a middle element. If an element is considered to be "connected" to another element, it can be directly connected to another element or there can be a middle element. If present, the terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used in the present application are for illustrative purposes only and are not the only embodiment.

[0064] Referring to Figure 1 An embodiment of the present application provides an auxiliary centering device based on hole edge chamfering, which comprises a support 110, a rod portion 120, a head portion 130, a plurality of protrusions 140, a plurality of detection members 150 and a plurality of compensation assemblies. The support 110 is used for connecting with a tool shank 210. The rod portion 120 is connected to the tool shank 210. The head portion 130 is connected to one end of the rod portion 120 away from the support 110. The plurality of protrusions 140 are connected to the head portion 130 and are distributed along the circumference of the head portion 130. The plurality of detection members 150 are connected to the rod portion 120 and are distributed along the circumference of the rod portion 120. Each detection member 150 is provided in one-to-one correspondence with one protrusion 140. The detection member 150 is used for detecting a strain signal of the corresponding protrusion 140.

[0065] The aforementioned auxiliary alignment device based on the chamfered edge of the hole measures the strain value of the protrusion 140 through the detection element 150, thereby determining the force acting on the protrusion 140; furthermore, it can determine the pre-compression depth and coordinates of the protrusion 140; and thus calculate the coordinates of the central axis of the head 130. Based on the coordinates of the central axis of the head 130 and the coordinates of the workpiece central axis, the offset compensation amount is determined, thereby compensating the workpiece so that the coordinates of the workpiece central axis coincide with the coordinates of the central axis of the head 130, achieving alignment between the assembly hole and the auxiliary alignment device. This, in turn, aligns the assembly hole with the tool holder 210 connected to the auxiliary alignment device, that is, the high-precision alignment of the center of the workpiece assembly hole with the center of the tool holder 210, ensuring the alignment accuracy of the subsequent processing device connected to the tool holder 210 with the assembly hole, ensuring the uniformity of the strengthening of the assembly hole surface, thereby ensuring the strengthening quality and the fatigue performance of the workpiece with the hole.

[0066] Understandably, the shape of the head 130 is adapted to the shape of the chamfer at the edge of the workpiece hole; that is, the head 130 is a tapered cylinder whose diameter gradually and uniformly decreases along the vertical direction. In some embodiments, the diameter D1 of the head 130 can be 12mm to 36mm, the length L1 of the head 130 along the vertical direction can be 4mm to 10mm, the length L2 of the rod 120 can be 3 to 6 times the length of the head 130, and the diameter D2 of the rod 120 can be 8mm to 12mm. This ensures rigidity while making the strain signal measurement more obvious.

[0067] In some embodiments, the bracket 110 can be fixed to the outside of the tool holder 210 by fasteners that are evenly distributed around the circumference. The fasteners can be screws or bolts, etc.

[0068] like Figure 1 As shown, in one embodiment, multiple detection elements 150 are evenly arranged, with each detection element 150 located at the end of the rod 120 away from the head 130. This even arrangement allows each detection element 150 to detect strain signals from its corresponding protrusion 140 at different circumferential positions. This provides a more comprehensive and balanced acquisition of the strain of the protrusion 140 throughout the entire circumference. It avoids the problem of incomplete strain monitoring or inconsistent monitoring accuracy in some areas due to uneven distribution of the detection elements 150, thus enabling a more accurate understanding of the actual stress and strain state at each protrusion 140 and facilitating accurate assessment of the overall alignment of the device.

[0069] In some embodiments, the detection element 150 includes a working strain gauge. When the protrusion 140 contacts the chamfer of the hole edge, the rod 120 bends and compresses, and the shape and size of the rod 120 change accordingly. The strain gauge can convert this mechanical strain into a measurable change in electrical signal, thereby reflecting the strain at the location.

[0070] The auxiliary centering device further comprises a plurality of compensation strain gauges 160, which compensate for strain caused by environmental factors such as temperature changes. Because the electrical characteristics of the strain gauges, such as resistance, change not only with mechanical strain but also with environmental temperature and other factors, the compensation strain gauges 160, through proper arrangement and cooperation with the working strain gauges, can eliminate the interference of temperature and other non-stress factors on strain measurement, improving the accuracy of measurement. The number of compensation strain gauges 160 corresponds to the number of working strain gauges. The compensation strain gauges 160 can be connected to the bracket 110, and the bracket 110 is further provided with a power supply 170, so that the plurality of compensation strain gauges 160 and the plurality of working strain gauges form a half-bridge circuit to measure one-way strain. When the working strain gauges are strained due to stress, the resistance value changes, which breaks the electrical balance of the half-bridge circuit, and then generates a corresponding change in voltage output. The compensation strain gauges 160 are not stressed or only affected by environmental factors, and their environment is basically the same as that of the working strain gauges. On the basis of eliminating the interference of environmental factors, by measuring the change in voltage difference and other electrical quantities output by the half-bridge circuit, the actual strain value can be calculated according to the corresponding strain electrical measurement principle.

[0071] In the present embodiment, the number of working strain gauges and compensation strain gauges 160 can be three. The three working strain gauges are uniformly connected, for example, bonded, to the upper end of the rod portion 120, which is the position of maximum strain, and are arranged 120 degrees apart to measure the strain of the rod portion 120. The three compensation strain gauges 160 can be bonded to the outer circumferential side of the bracket 110 to compensate for temperature. The projection of each working strain gauge on the horizontal plane is collinear with the projection of the corresponding protrusion 140 on the horizontal plane, that is, the projections of the two are distributed along the radial direction, and the connecting line of the projections points to the center of the circle.

[0072] In other embodiments, the detection member 150 can also be a piezoelectric film sensor. When the piezoelectric film material (such as a polyvinylidene fluoride thin film of a high-molecular polymer with piezoelectric properties) of the piezoelectric film sensor is subjected to strain, it will generate a change in electric charge on its surface due to the piezoelectric effect, and the strain signal can be obtained by detecting the change in electric charge.

[0073] In some embodiments, the detection member 150 can also be a capacitive strain sensor, which detects the strain signal by utilizing the change in distance, relative area, and other factors between the capacitor plates with strain, thereby causing a change in capacitance value. When the measured object is strained, it will cause the plates of the capacitive sensor to displace accordingly, causing the capacitance value to fluctuate accordingly, and the strain size can be calculated by detecting the change in capacitance value.

[0074] In one of the embodiments, the plurality of protrusions 140 are detachably connected to the head 130. During use, the protrusions 140 can be worn, damaged, etc. due to long-term contact with other components, friction, or external environmental influences. With the detachable connection, when a protrusion 140 has a problem, instead of complex disassembly or replacement of the entire device, the problematic protrusion 140 can be individually disassembled for repair or replacement with a new protrusion 140, which greatly reduces maintenance costs and time costs, and enables the device to quickly return to normal use. With changes in use scenarios, different requirements for the size, shape, material, etc. of the protrusions 140 can be required. The detachable connection allows different specifications of protrusions 140 to be easily replaced according to actual needs, such as when centering operations are required for holes with different diameters and different accuracy requirements, the corresponding suitable protrusions 140 can be replaced to meet the new work requirements, enhancing the adaptability of the device to different application scenarios.

[0075] As shown in Figure 1 In one of the embodiments, the auxiliary centering device further includes a signal transmitting device 180 connected to the bracket 110, and the signal transmitting device 180 is in communication connection with the detection piece 150; the auxiliary centering device further includes a signal receiving device 190, and the signal receiving device 190 is in communication connection with the signal transmitting device 180. The strain signal corresponding to the protrusion 140 detected by the detection piece 150 can be transmitted outward through the signal transmitting device 180 in communication connection with it, and then received by the signal receiving device 190, realizing the transmission of data from the centering device on site to the external receiving end. This allows the operator to obtain the strain signal data of the device during the centering operation in real time, regardless of the distance from the centering device, as long as the signal transmission coverage allows, the working state of the device can be known in time, facilitating dynamic monitoring and corresponding adjustment.

[0076] As shown in Figure 1 In some embodiments, the signal receiving device 190 is in communication connection with a computing device such as a computer. With the powerful computing and analysis functions of the computer, the received strain signal data can be deeply processed using professional algorithms, such as by comparing data at different times and different positions to analyze the trend of the strain signal, so as to more accurately judge the direction, size, etc. of the centering deviation, which helps to improve the accuracy and efficiency of the centering operation.

[0077] As shown in Figure 1 In some embodiments, the signal transmitting device 180 can be connected to the outside of the bracket 110 through fasteners such as screws, etc.

[0078] As shown in Figure 1As shown, in some embodiments, the auxiliary centering device further comprises a transmitter 220. The transmitter 220 can amplify the strain signal detected by the detection member 150 to a suitable range, ensuring that the signal can be accurately and stably received by the signal receiving device 190 and transmitted to a terminal such as a computer for processing. Moreover, the transmitter 220 can also remove noise interference.

[0079] In one of the embodiments, a force gauge can also be introduced, which is used to measure the vertical force acting on the protrusion 140. By measuring the actual vertical force through the force gauge, the theoretical vertical force can be compared to intuitively evaluate the accuracy of the current centering operation.

[0080] As Figures 2 to 8 As shown, an embodiment of the present application also provides a centering method based on the chamfer of the hole edge. Based on the above auxiliary centering device based on the chamfer of the hole edge, the centering method comprises:

[0081] Step 110, controlling the auxiliary centering device to move downward along the vertical direction to make the protrusion abut against the chamfer of the hole edge.

[0082] In some embodiments, the workpiece with holes can be pre-installed on the workbench, and the workbench can position the central axis of the assembly hole to achieve preliminary centering. It can be understood that the workbench is located below the auxiliary centering device. The auxiliary centering device can be connected below the tool holder, for example, connected to the tool holder, that is, the tool holder is located above the workbench. The auxiliary centering device is driven by the tool holder to move downward along the vertical direction, so that the head of the auxiliary centering device is pressed downward by a certain depth relative to the assembly hole, and then the protrusion abuts against the chamfer of the hole edge.

[0083] In some embodiments, the depth of the head pressed downward relative to the assembly hole can vary according to different materials. The depth of the press-down can be 30 microns to 80 microns, which ensures that the workpiece does not deform excessively, and at the same time, it can ensure that a sufficient and obvious strain signal can be detected.

[0084] Step 120, obtaining the strain signal of the detection member.

[0085] When the protrusion contacts the chamfer of the hole edge, because of the centering deviation, the rod part is not only compressed but also bent, so the strain gauge connected to the rod part can detect the corresponding strain signal. The detection member includes working strain gauges, and the auxiliary centering device further includes a plurality of compensation strain gauges, the number of which corresponds to the number of working strain gauges. The compensation strain gauges can be connected to the bracket, and the plurality of compensation strain gauges and the plurality of working strain gauges form a half-bridge circuit to measure unidirectional strain.

[0086] In the embodiment, the number of working strain gauges and compensation strain gauges can be three, the three working strain gauges are uniformly connected, for example, bonded, at the upper side end of the rod part, which is the maximum strain position, each working strain gauge is arranged at an interval of 120 degrees, and the strain of the rod part is measured. The three compensation strain gauges can be bonded at the outer circumferential side of the bracket for compensating temperature. The projection of each working strain gauge on the horizontal plane is collinear with the projection of the corresponding position of the protrusion on the horizontal plane, that is, the projections of the two are distributed along the radial direction, and the connecting line of the projections points to the center of the circle.

[0087] In some embodiments, a transmission unit can be arranged on the auxiliary centering device, the transmission unit is in communication connection with the detection member, and the transmission unit can transmit the strain signal of the detection member to a computing device, for example, a computer.

[0088] In step 130, the coordinates of the center axis of the head are calculated.

[0089] In some embodiments, taking the number of protrusions and detection members as an example, three strain signals are used to calculate the coordinates of the center axis of the head, and the coordinates of the center axis of the head are the coordinates of the center axis of the centering device.

[0090] In step 140, based on the coordinates of the center axis of the head and the coordinates of the center axis of the workpiece, the offset compensation amount is determined.

[0091] Since the workpiece is pre-installed on the workbench, the position of the workbench is known, and thus the position and coordinates of the center axis of the workpiece can be obtained. Based on the coordinates of the center axis of the head and the coordinates of the center axis of the workpiece, the offset compensation amount can be determined. In some embodiments, when the head and the chamfer are in the same horizontal plane, the offset compensation amount can be determined by the coordinates of the center of the head and the coordinates of the center of the chamfer.

[0092] In step 150, the workbench is repeatedly controlled to move in the horizontal direction, and the strain signal change values of the plurality of detection members are obtained until the strain signal change values of the plurality of detection members are all less than a preset value.

[0093] After the offset compensation amount is determined, the workbench drives the workpiece to move left and right or forward and backward in the horizontal direction, so that the center axis of the workpiece is collinear with the center axis of the head. When the workbench drives the workpiece to move for offset compensation, the plurality of detection members detect the strain signals respectively. When the change values of the plurality of strain signals are greater than a preset value, the workbench can continue to move until the strain signal change values of the plurality of detection members are all less than the preset value, that is, the stress of the plurality of protrusions is basically the same, which indicates that the center axis of the head is aligned with the center axis of the workpiece, and it is considered that the centering operation is completed.

[0094] After the centering is completed, the corresponding machining device can be switched, and the machining device is connected to the tool holder, so as to perform precision machining and strengthening treatment on the assembly hole and the hole edge.

[0095] In one embodiment, the method of calculating the coordinates of the center axis of the head includes:

[0096] Step 131, establishing the relationship between the strain value and the force to calculate the force on the plurality of protrusions.

[0097] Since the rod portion is connected with the detection member for detecting the strain value, the strain value can be obtained, and the force on the protrusions can be calculated by establishing the relationship between the strain value and the force.

[0098] Specifically, when the head is vertically pressed to the assembly hole, the rod portion is not only compressed but also bent due to the misalignment.

[0099] Taking one of the protrusions as an example, the protrusion is subjected to a vertical force , the rod portion is compressed, and the first compressive strain brought to the working strain gauge is , satisfying the following relationship:

[0100] ;

[0101] In the formula, is the cross-sectional area of the rod portion, is the elastic modulus of the rod portion.

[0102] Due to the misalignment, the protrusion is subjected to a horizontal force , the rod portion is bent, and the tensile strain brought to the working strain gauge is , satisfying the following relationship:

[0103] ;

[0104] In the formula, is the equivalent length of the protrusion to the working strain gauge, is the radius of the rod portion, is the angle between the force direction of the protrusion in the horizontal plane and the working strain gauge, since the projection of the protrusion in the horizontal plane is collinear with the projection of the strain gauge, the angle should be 0, is the moment of inertia of the rod portion.

[0105] Understandably, if there is no misalignment, the forces on the three protrusions are the same, the horizontal resultant force in the horizontal plane is 0, and the rod portion does not bend.

[0106] The protrusion is subjected to a vertical force , the rod portion is bent, and the second compressive strain brought to the working strain gauge is , as follows:

[0107] ;

[0108] In the formula, is the head radius.

[0109] By using the strain superposition principle, the sum of the first compressive strain, the second compressive strain and the tensile strain is the strain value at the working strain gauge , as follows:

[0110] .

[0111] According to the geometric relationship, the horizontal force can be determined and the vertical force satisfy the following relationship:

[0112] ;

[0113] In the formula, is the chamfer angle, is the friction coefficient between the protrusion and the chamfer.

[0114] That is, the horizontal force can also be represented by the vertical force through the geometric relationship. By combining multiple relationships, the vertical force of the protrusion can be obtained, and then the horizontal force can be calculated according to the geometric relationship.

[0115] In some embodiments, the three working strain gauges can be affected by the vertical force of the three protrusions. In order to improve the centering accuracy, the following relationship can be used for calibration, that is:

[0116] ;

[0117] In the formula, is the vertical force of the three protrusions, is the interval angle between the three protrusions, is the force correction coefficient, which can be selected according to experience or experiment, , , is the strain value of the three protrusions.

[0118] In some embodiments, the neutral axis of the centering device can be determined according to the horizontal force of multiple protrusions.

[0119] Specifically, according to the horizontal force of each protrusion, the horizontal resultant force can be calculated, and the direction of the horizontal resultant force can be used to determine the position of the neutral axis of the centering device. The neutral axis passes through the center of the head, and is perpendicular to the direction of the horizontal resultant force and the compensation direction, as shown in Figure 7 .

[0120] Step 132, establishing the relationship between the force and the pre-pressing depth to calculate the pre-pressing depth of multiple protrusions.

[0121] In some embodiments, based on the aforementioned vertical force It can calculate the normal force acting on the protrusion. It satisfies the following relationship:

[0122] .

[0123] Based on Hertz's contact principle, the contact radius between the protrusion and the chamfer can be calculated using the normal force. It satisfies the following relationship:

[0124] ;

[0125] In the formula, The chamfer radius is... The radius of the protrusion. The width of the chamfer. It is the equivalent elastic modulus for the convex and chamfered sections.

[0126] The first displacement caused by contact deformation can be calculated based on the contact radius. :

[0127] .

[0128] The second displacement caused by the bending of the rod under a horizontal force is :

[0129] ;

[0130] In the formula, This is the equivalent length of the rod.

[0131] The third displacement caused by the compression deformation of the rod under vertical force is :

[0132] .

[0133] Based on the first, second, and third displacements, the preload depth of the protrusion can be determined. :

[0134] .

[0135] Therefore, based on geometric relationships, the vertical preloading depth of the protrusion... :

[0136] , This is a correction factor for the vertical preloading depth. The correction factor can be selected based on experience or experiments.

[0137] Horizontal preload depth of the protrusion :

[0138] , is a correction coefficient of the horizontal pre-pressing depth, and the correction coefficient can be selected according to experience or experiment.

[0139] In this way, the vertical pre-pressing depth and the horizontal pre-pressing depth of each protrusion can be calculated in sequence, the vertical displacement of the workbench can be determined through the vertical pre-pressing depth, and the horizontal displacement of each protrusion can be determined through the horizontal pre-pressing depth, facilitating subsequent offset compensation.

[0140] Step 133, calculating the coordinates of the protrusions according to the pre-pressing depths of the protrusions.

[0141] Specifically, the position angle of the protrusion can be calculated based on the position angle of the hole chamfer .

[0142] .

[0143] Understandably, when the coordinate system is determined, because the interval angle between the three protrusions is known, the position angle is known, for example, the position angles of the three protrusions are 30 degrees, 150 degrees and 270 degrees respectively.

[0144] Let the center coordinates of the hole chamfer be O'(0, 0), based on the center coordinates of the hole chamfer O' and the hole chamfer radius R W , the coordinates of the point Q on the hole chamfer can be calculated .

[0145] .

[0146] Further, based on the coordinates of the three points Q1, Q2 and Q3 on the hole chamfer, based on the equivalent radius of the head , based on the horizontal pre-pressing depth of the protrusion and the position vector of the protrusion , the coordinates of the three protrusions can be calculated respectively, and the coordinates of the protrusion O satisfy the following relationship:

[0147] .

[0148] Step 134, calculating the coordinates of the center axis of the head according to the coordinates of the protrusions.

[0149] After the coordinates of the three protrusions are calculated respectively, the coordinates of the center axis of the head can be solved, so that the offset compensation amount can be determined according to the coordinates of the center axis of the workpiece.

[0150] ​In some embodiments, before the aforementioned centering process, the device can also be calibrated, for example, steps 110 to 150 are performed, single convex implementation can be calibrated, and hardware deviation and simplification deviation can be calibrated, thereby improving the centering accuracy.

[0151] In some embodiments, the device can be calibrated by using a force gauge, which is equivalent to measuring the actual vertical force and horizontal force by using the force gauge, and comparing with the theoretical vertical force and theoretical horizontal force calculated in the foregoing.

[0152] At a certain pre-pressing depth, in addition to the aforementioned centering deviation, the strain signal value is affected by the possible existence of hardware deviation and simplification deviation. The hardware deviation mainly includes the verticality of the head, the pasting state of the strain gauge, and the distribution position of the strain gauge. The position coordinates of the force signal generated by the force gauge are recorded, and when the head is installed to produce a deviation, different convexes are away from the center of the rod at different distances, so that the three convexes cannot be in contact with the hole edge chamfer at the same time, thereby generating three different strain signals, so as to determine the head deviation. The same strain caused by different pasting states of the strain gauge leads to different strain signal values, so the sensitivity of each strain gauge is calculated. The corresponding theoretical strain value is calculated by strain analysis, and compared with the measured value of each strain gauge to determine the true sensitivity. Then, the influence of the pasting position of the strain gauge, the distribution position of the three strain gauges is not uniform, which leads to different strain values of the strain gauges. The true distribution position can be determined by experimental strain value and theoretical calculation.

[0153] The simplification deviation mainly includes the influence of the deformation of the rod in the strain analysis, when the pre-pressing depth is too large, the rod is bent too much, which leads to the change of the contact state of the head and the chamfer, and the compression amount is reduced. Therefore, appropriate pre-pressing depth is adopted to reduce the influence of deformation, and a certain proportion coefficient is used to correct the theoretical strain value.

[0154] After the calibration of the hardware deviation and the simplification error, the centering operation can be realized by the foregoing method.

[0155] In order to evaluate the centering accuracy, the vertical force and the horizontal force are measured by using a force gauge and other tools. The comparison between the theoretical value and the experimental value of the force is shown in Figure 9 The horizontal force is the aforementioned horizontal force, and the vertical force is the aforementioned vertical force. At the same time, as shown in Figure 10As shown, the displacement of the workbench in the vertical direction represents the actual pre-pressing depth, and the actual pre-pressing depth is compared with the vertical displacement of the workbench calculated by the auxiliary centering device (i.e. the theoretical pre-pressing depth). It can be seen that the error between the theoretical value and the experimental value of the pre-pressing depth, the horizontal force and the vertical force is small. Thus, the device and the method can improve the centering accuracy of the assembly hole of the workpiece with a hole and the processing device, and further ensure the subsequent processing quality. In some embodiments, the auxiliary centering device can also measure the processing pressure after the centering operation is completed. Specifically, the vertical force, i.e. the processing pressure, can be calculated by the strain value collected by the strain gauge, which meets the requirement of precise processing of the hole edge.

[0156] The technical features of the above embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered as falling within the scope of the present disclosure.

[0157] The above embodiments only express several implementation manners of the present application, and the description is specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be pointed out that for those skilled in the art, some modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. An auxiliary centering device based on hole edge chamfering, characterized in that, The auxiliary centering device based on hole edge chamfering includes: The bracket is used for connection with the tool holder; The shank is connected to the tool holder; The head is connected to the end of the rod that is away from the bracket; Multiple protrusions are connected to the head and distributed circumferentially along the head; Multiple detection elements are connected to the rod and distributed circumferentially along the rod; each detection element is provided in a one-to-one correspondence with a protrusion; the detection element is used to detect the strain signal of the corresponding protrusion.

2. The auxiliary centering device based on hole edge chamfering according to claim 1, characterized in that, The plurality of the detection elements are evenly arranged, and the detection elements are located at the end of the rod away from the head.

3. The auxiliary centering device based on hole edge chamfering according to claim 1, characterized in that, The projection of the protrusion in the horizontal plane is collinear with the projection of the detection element in the horizontal plane.

4. The auxiliary centering device based on hole edge chamfering according to claim 1, characterized in that, The plurality of protrusions are detachably connected to the head.

5. The auxiliary centering device based on hole edge chamfering according to claim 1, characterized in that, The auxiliary alignment device also includes a signal transmitting device connected to the bracket, and the signal transmitting device is communicatively connected to the detection element. The auxiliary centering device also includes a signal receiving device, which is communicatively connected to the signal transmitting device.

6. A centering method based on hole edge chamfering, characterized in that, Based on the auxiliary centering device based on hole edge chamfering as described in any one of claims 1 to 5, the centering method includes: The control auxiliary centering device moves downward vertically so that the protrusion abuts against the chamfer of the hole edge; Acquire the strain signal of the test specimen; Calculate the coordinates of the head's midline; The offset compensation amount is determined based on the coordinates of the head centerline and the workpiece centerline. Repeatedly control the worktable to move horizontally and acquire the strain signal change values ​​of multiple test pieces until the strain signal change values ​​of multiple test pieces are all less than the preset value.

7. The centering method based on hole edge chamfering according to claim 6, characterized in that, The method for calculating the coordinates of the head's central axis includes: Establish the relationship between strain values ​​and applied forces to calculate the forces acting on multiple protrusions; Establish the relationship between the applied force and the preload depth to calculate the preload depth of the plurality of protrusions; The coordinates of the protrusions are calculated based on the pre-compression depth of the protrusions. The coordinates of the central axis of the head are calculated based on the coordinates of the multiple protrusions.

8. The centering method based on hole edge chamfering according to claim 7, characterized in that, The method for establishing the relationship between strain values ​​and applied forces to calculate the forces acting on multiple protrusions includes: Obtain the first compressive strain, second compressive strain, and tensile strain for each protrusion; Obtain the strain value for each protrusion, which is the sum of the first compressive strain, the second compressive strain, and the tensile strain; Calculate the vertical force acting on the protrusion based on the strain value; Calculate the horizontal force on the protrusion based on the vertical force.

9. The centering method based on hole edge chamfering according to claim 8, characterized in that, The method for establishing the relationship between the applied force and the preload depth to calculate the preload depth of the plurality of protrusions includes: Calculate the normal force on the protrusion based on the vertical force; Calculate the contact radius between the protrusion and the chamfered edge of the hole; Based on the contact radius, calculate the first displacement of the protrusion caused by contact deformation; Calculate the second displacement caused by the protrusion due to the bending of the rod by the horizontal force. The third displacement caused by the protrusion due to the compression deformation of the rod under vertical force is calculated. The preload depth of the protrusion is determined based on the first displacement, the second displacement, and the third displacement. Calculate the horizontal preload depth of the protrusion based on its preload depth.

10. The centering method based on hole edge chamfering according to claim 9, characterized in that, The method for calculating the coordinates of the protrusions based on the pre-compression depth of the plurality of protrusions includes: Calculate the position vector of the protrusion based on its position angle; Calculate the coordinates of points on the chamfered edge of the hole based on the coordinates of the center of the chamfer and the radius of the chamfer. The coordinates of the protrusion are calculated based on the coordinates of the points on the chamfered edge of the hole, the equivalent radius of the head, the horizontal preload depth of the protrusion, and the position vector of the protrusion.

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