Efficient machining process for thin-wall structural part

Abstract

The invention discloses an efficient machining process for a thin-wall structural part, which belongs to the technical field of machining and comprises the following steps: step 1, supporting a workpiece blank above a machine tool worktable by adopting a shape follow-up supporting tool; 2, a plurality of vibration sensors are arranged on the back side of the to-be-machined end face of the workpiece blank; thirdly, rough milling is conducted on the upward end face through an unequal-distance layer cutting method; 4, the cavities in the end faces are sequentially subjected to rough milling in a spiral milling and plunge milling combined mode; and 5, finish machining is conducted on the end face and the cavity according to the precision requirement. In the rough machining process of the end face and the cavity, the feeding speed is adjusted through the cutting force monitored by the force sensor on the cutter bar of the corresponding cutter, the cutting depth is adjusted through the vibration amplitude monitored by the vibration sensor closest to the corresponding cutter, the situation that the vibration amplitude is too large is prevented, deformation caused in the machining process is reduced, and the machining efficiency is improved. And the qualified rate of end face and cavity machining is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical processing, and in particular relates to a high-efficiency processing technology for thin-walled structural parts. Background Art

[0002] Thin-walled structural parts are widely used in high-precision products due to their lightweight and high-strength characteristics. They require machining of end faces and cavities. Thin-walled structural parts are usually rough-machined first, with the end faces and cavities milled, and then fine-machined according to the precision requirements. During the rough machining of thin-walled structural parts, when milling layer by layer, the cutting depth and feed speed of the tool remain unchanged during each layer. When the vibration amplitude caused by residual stress during the machining process is too large, it will cause machining deformation and reduce the qualified rate of structural parts machining. In addition, before machining the end faces and cavities of thin-walled structural parts on the machine tool, most of them use rigid clamps to fix the two ends. Due to the lack of support at the bottom end, the vibration will be aggravated during the machining process, which will lead to deformation during the machining process and affect the machining quality. Summary of the Invention

[0003] In order to solve the problems of easy deformation and low pass rate of thin-walled structural parts during processing caused by existing processing technology and only using rigid clamps for clamping, the present invention provides an efficient processing technology for thin-walled structural parts.

[0004] A high-efficiency processing technology for thin-walled structural parts includes the following steps: Step 1: Use a conformal support fixture to support the workpiece blank above the machine tool worktable. The two ends of the workpiece blank are fixed by rigid clamps, with the end surface to be processed facing upwards. Step 2: Arrange a plurality of vibration sensors on the back side of the end face to be processed of the workpiece blank, wherein the arrangement density of the vibration sensors in the high stress area is greater than that in other areas; The vibration sensor is connected to the machine tool control system for communication, and the machine tool control system obtains the position of the vibration sensor and the monitored vibration amplitude signal; Step 3: Rough milling the upward end face using the unequally spaced layer cutting method. During the machining process, the machine tool control system adjusts the feed rate based on the cutting force monitored by the force sensor on the end face machining tool bar and adjusts the cutting depth based on the vibration amplitude monitored by the vibration sensor closest to the end face machining tool. Step 4: Rough milling is performed on the cavities on the end faces in sequence using a combination of spiral milling and plunge milling. During each cavity machining process, the machine tool control system adjusts the feed rate based on the cutting force monitored by the force sensor on the tool bar of the cavity machining tool, and adjusts the cutting depth based on the vibration amplitude monitored by the vibration sensor closest to the cavity machining tool. Step 5: Finish the end face and cavity according to the accuracy requirements.

[0005] Preferably, in step 2, the high stress area refers to: an area on the workpiece blank corresponding to an area in the thin-walled structural component where the wall thickness is less than 2 mm or the curvature radius is less than 10 mm.

[0006] Preferably, step 3 includes the following sub-steps: Step 31, according to the thickness of the end face to be processed that needs to be roughly milled off, the cutting depth of each layer and the number of milling layers are determined in a manner of increasing the milling depth layer by layer; Step 32: Milling is performed layer by layer. The milling process of each layer is as follows: Step 321 , the end surface machining tool is milled and cut along an S-shaped tool path; Step 322, let i = 1, i represents the serial number of the monitoring time during end surface processing; Step 323: The force sensor on the end machining tool shank monitors the cutting force, and each vibration sensor monitors the vibration amplitude, and transmits the monitoring data at the i-th monitoring moment to the machine tool control system; Step 324 , when the vibration amplitude detected by the vibration sensor closest to the end surface machining tool at the i-th monitoring moment is greater than the amplitude threshold, the cutting depth of the end surface machining tool is reduced by 5%; otherwise, the cutting depth remains unchanged; When the cutting force monitored by the force sensor on the tool bar of the end-face machining tool at the i-th monitoring moment is greater than the critical value of the cutting force, the feed speed of the end-face machining tool is reduced by 5%; otherwise, the feed speed remains unchanged; Step 325, let i=i+1; The end surface machining tool proceeds to the i-th monitoring moment by milling according to the S-shaped tool path based on the adjusted cutting depth and feed speed, and then enters step 323.

[0007] Preferably, in step 4, the processing of each cavity includes the following sub-steps: Step 41: Based on the thickness of the cavity to be machined that needs to be rough-milled compared to the end face after rough machining, the cutting depth of each layer and the number of spiral milling layers are determined in a manner that the cutting depth increases layer by layer or the cutting depth of each layer is consistent. The cutting depth of each layer and the number of plunge milling layers are determined in a manner that the cutting depth of each layer is consistent. Step 42: Drilling a clearance hole at the center of the rough-machined end surface corresponding to the cavity. The drilling depth of the clearance hole is the thickness of the cavity to be machined that needs to be roughly milled compared to the rough-machined end surface. The milling cutter for cavity machining enters the avoidance hole; Step 43, performing spiral milling layer by layer on the middle area of ​​the cavity to be processed; Step 44, performing plunge milling layer by layer on the four corners of the cavity to be processed.

[0008] Preferably, in step 43, when spiral milling is performed layer by layer on the middle area of ​​the cavity to be processed, the milling process of each layer is as follows: Step 431 , the cavity machining milling cutter moves along the Archimedean spiral trajectory to perform side milling; Step 432, let j = 1, where j represents the serial number of the monitoring moment when the middle area of ​​the cavity is processed; Step 433: The force sensor on the milling cutter bar for cavity machining monitors the cutting force, and each vibration sensor monitors the vibration amplitude, and transmits the monitoring data at the jth monitoring moment to the machine tool control system; Step 434: when the vibration amplitude detected by the vibration sensor closest to the cavity machining milling cutter at the jth monitoring moment is greater than the amplitude threshold, the cutting depth of the cavity machining milling cutter is reduced by 5%; otherwise, the cutting depth remains unchanged; When the cutting force monitored by the force sensor on the cutter bar of the cavity machining milling cutter at the jth monitoring moment is greater than the critical value of the cutting force, the feed speed of the cavity machining milling cutter is reduced by 5%; otherwise, the feed speed remains unchanged; Step 435, let j=j+1; The cavity machining milling cutter proceeds to the jth monitoring moment along the Archimedean spiral trajectory based on the adjusted cutting depth and feed speed, and then enters step 433.

[0009] Preferably, in step 44, when the positions of the four corners of the cavity to be processed are plunge milled layer by layer, the plunge milling process for each corner and each layer is as follows: Step 441, determining the moving path of the plunge milling cutter for cavity machining; Starting from one end of the arc edge in each corner area, the cavity machining plunge milling cutter moves along the arc trajectory to the other end to form a new arc edge; After that, the cavity machining plunge milling cutter is reset to one end of the new arc edge and the above process is repeated; In the above process, the cavity machining plunge milling cutter performs a downward plunge milling operation every time it moves to a tool position along the arc trajectory, and then lifts the tool to move to the next tool position; Step 442, let k = 1, where k represents the sequence number of the monitoring time when the four corner areas of the cavity are processed; Step 443: The force sensor on the cavity machining plunge milling cutter shank monitors the cutting force, and each vibration sensor monitors the vibration amplitude, and transmits the monitoring data at the kth monitoring moment to the machine tool control system; Step 444 , when the vibration amplitude detected by the vibration sensor closest to the cavity machining plunge milling cutter at the kth monitoring moment is greater than the amplitude threshold, the cutting depth of the cavity machining plunge milling cutter is reduced by 5%; otherwise, the cutting depth remains unchanged; When the cutting force monitored by the force sensor on the tool shank of the cavity machining plunge milling cutter at the kth monitoring moment is greater than the critical value of the cutting force, the feed speed of the cavity machining plunge milling cutter is reduced by 5%; otherwise, the feed speed remains unchanged; Step 445, set k=k+1; The cavity machining plunge milling cutter proceeds to the kth monitoring moment according to the tool path in step 441 based on the adjusted cutting depth and feed speed, and then enters step 443.

[0010] Preferably, the conformable support fixture comprises a base plate, on which a support column is provided which can be raised and lowered in a vertical direction, and a support head made of EAP material is fixedly provided at the top end of the support column; An electrode sheet is arranged inside the support head, and the electrode sheet forms a closed loop with the power supply and the voltage regulator.

[0011] Preferably, a silicone layer is bonded to the top of the support head.

[0012] Preferably, a piezoelectric sensor is provided at the position where the support head contacts the support column.

[0013] Preferably, a temperature sensor is provided at the position where the support head contacts the support column.

[0014] The beneficial effects of the present invention are: (1) During the rough machining of the end face and the cavity, the present invention adjusts the feed speed by the cutting force monitored by the force sensor on the tool shank of the corresponding tool, and adjusts the cutting depth by the vibration amplitude monitored by the vibration sensor closest to the corresponding tool, so that the amplitude of the vibration at the machining position and the machining force of the tool are both within the corresponding critical values ​​during the machining process, thereby preventing the vibration amplitude from being too large, thereby reducing the deformation caused by the machining process and improving the qualified rate of the end face and cavity machining.

[0015] (2) In the present invention, the workpiece blank is clamped by a combination of a rigid clamp fixing both ends and a conformal support fixture supporting the bottom end. The support of the conformal support fixture reduces the vibration of the workpiece blank during processing, thereby reducing deformation during processing and improving processing quality.

[0016] (3) In the conformable support tooling of the present invention, the support column can be raised and lowered, so it can adapt to the support of flat surfaces and curved surfaces, and has a wide range of applications.

[0017] (4) In the conformable support tooling of the present invention, a support head is provided at the top of the support column. The support head is made of EAP material and can produce a slight deformation after being electrically stimulated, thereby adjusting the support force with high adjustment accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings in the specification, which constitute a part of this application, are used to provide further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute improper limitations on this application.

[0019] Figure 1 It is a schematic diagram of the process flow of the efficient processing technology of thin-walled structural parts of the present invention; Figure 2 This is a schematic diagram of the S-shaped tool path of the end face machining tool in the present invention; Figure 3 It is a schematic diagram of the Archimedean spiral trajectory of the medium-sized cavity processing milling cutter of the present invention; Figure 4 It is a schematic diagram of the movement path of the plunge milling cutter position for machining a medium-sized cavity according to the present invention; Figure 5 Schematic diagram of the support of a plane by a conformable support tool in the present invention; Figure 6 Schematic diagram of the support of the curved surface by the conformal support tooling in the present invention; Figure 7 This is a schematic diagram of the coordination of the substrate, support column, and support head in the present invention; in: 1. Substrate; 2. Support column; 3. Support head; 4. Electrode sheet; 5. Silicone layer; 6. Piezoelectric sensor; 7. Temperature sensor; 8. Nut. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Example 1: like Figure 1 As shown, a high-efficiency processing technology for thin-walled structural parts includes the following steps: Step 1: Use a conformal support fixture to support the workpiece blank above the machine tool worktable. The two ends of the workpiece blank are fixed by rigid clamps, with the end surface to be processed facing upwards. Step 2: Arrange a plurality of vibration sensors on the back side of the end face to be processed of the workpiece blank, wherein the arrangement density of the vibration sensors in the high stress area is greater than that in other areas; The vibration sensor is connected to the machine tool control system for communication, and the machine tool control system obtains the position of the vibration sensor and the monitored vibration amplitude signal; Step 3: Rough milling the upward end face using the unequally spaced layer cutting method. During the machining process, the machine tool control system adjusts the feed rate based on the cutting force monitored by the force sensor on the end face machining tool bar and adjusts the cutting depth based on the vibration amplitude monitored by the vibration sensor closest to the end face machining tool. Step 4: Rough milling is performed on the cavities on the end faces in sequence using a combination of spiral milling and plunge milling. During each cavity machining process, the machine tool control system adjusts the feed rate based on the cutting force monitored by the force sensor on the tool bar of the cavity machining tool, and adjusts the cutting depth based on the vibration amplitude monitored by the vibration sensor closest to the cavity machining tool. Step 5: Finish the end face and cavity according to the accuracy requirements.

[0022] In the present application, the rough machining of the end face and the cavity has already completed the milling of most of the excess material of the workpiece blank compared to the formed thin-walled structural parts. For example, compared with the formed thin-walled structural parts, the thickness of the excess material to be milled on a certain end face of the workpiece blank is 5.2mm. During rough milling, the thickness of the milling is 5mm, and the remaining 0.2mm thickness of the excess material is milled by fine machining. Fine machining can be achieved by using existing technology, and the specific machining process will not be repeated. The same is true for the cavity. The milling of the remaining small-sized excess material after rough machining is achieved by the existing fine machining process. In addition, in the present application, during the rough milling of the end face and the cavity layer by layer, the cutting depth is adjusted based on the monitoring of the amplitude and cutting force. Therefore, there are unevennesses on the end face and the bottom surface of the cavity after the rough milling is completed. These unevennesses can be eliminated based on the precision requirements by using the existing fine machining process in the fine machining stage.

[0023] Preferably, in step 2, the high stress area refers to: an area on the workpiece blank corresponding to an area in the thin-walled structural component where the wall thickness is less than 2 mm or the curvature radius is less than 10 mm.

[0024] Preferably, step 3 includes the following sub-steps: Step 31, according to the thickness of the end face to be processed that needs to be roughly milled off, the cutting depth of each layer and the number of milling layers are determined in a manner of increasing the milling depth layer by layer; For example, if the thickness of the end face to be machined needs to be roughly milled off is 5mm, the milling depth of the first layer is 0.8mm, and the depth of cut between adjacent layers increases by 0.1~0.3mm. When the depth of cut between adjacent layers increases by 0.1mm, the milling depth of the second layer is determined to be 0.9mm, the milling depth of the third layer is 1.0mm, the milling depth of the fourth layer is 1.1mm, and the milling depth of the fifth layer is 1.2mm. Step 32: Milling is performed layer by layer. The milling process of each layer is as follows: Step 321, as Figure 2 As shown, the end face machining tool follows an S-shaped cutting path for milling; Step 322, let i = 1, i represents the serial number of the monitoring time during end surface processing; Step 323: The force sensor on the end machining tool shank monitors the cutting force, and each vibration sensor monitors the vibration amplitude, and transmits the monitoring data at the i-th monitoring moment to the machine tool control system; Step 324 , when the vibration amplitude detected by the vibration sensor closest to the end surface machining tool at the i-th monitoring moment is greater than the amplitude threshold, the cutting depth of the end surface machining tool is reduced by 5%; otherwise, the cutting depth remains unchanged; When the cutting force monitored by the force sensor on the tool bar of the end-face machining tool at the i-th monitoring moment is greater than the critical value of the cutting force, the feed speed of the end-face machining tool is reduced by 5%; otherwise, the feed speed remains unchanged; Specifically, the critical value of amplitude is 0.15 m / s², and the critical value of cutting force is 600 N; Step 325, let i=i+1; The end surface machining tool proceeds to the i-th monitoring moment by milling according to the S-shaped tool path based on the adjusted cutting depth and feed speed, and then enters step 323.

[0025] In this application, the milling depth is adjusted by the vibration amplitude monitored by the vibration sensor closest to the end face machining tool, and the feed speed is adjusted by the cutting force monitored by the force sensor on the tool shank of the end face machining tool, so that the vibration amplitude of the machining position and the machining force of the tool are within the corresponding critical values ​​during the machining process, preventing the vibration amplitude from being too large, thereby reducing the deformation caused by the machining process and improving the qualified rate of the end face machining.

[0026] Preferably, in step 4, the processing of each cavity includes the following sub-steps: Step 41: Based on the thickness of the cavity to be machined that needs to be rough-milled compared to the end face after rough machining, the cutting depth of each layer and the number of spiral milling layers are determined in a manner that the cutting depth increases layer by layer or the cutting depth of each layer is consistent. The cutting depth of each layer and the number of plunge milling layers are determined in a manner that the cutting depth of each layer is consistent. For example, the thickness of the cavity to be processed that needs to be rough-milled compared to the end face after rough machining is 3mm. The middle part of the cavity to be processed is subjected to spiral milling. The number of spiral milling layers is three. When the cutting depth increases layer by layer, the milling depth of the first layer of spiral milling is 0.8mm, wherein the cutting depth between adjacent layers increases by 0.2mm. The milling depth of the second layer is determined to be 1.0mm, and the milling depth of the third layer is 1.2mm. When the cutting depth of each layer is consistent, the milling depth of each layer of spiral milling is 1.0mm; the four corners of the cavity to be processed are subjected to plunge milling. The number of plunge milling layers is two, and the cutting depth of each layer is 1.5mm. Step 42: Drilling a clearance hole at the center of the rough-machined end surface corresponding to the cavity. The drilling depth of the clearance hole is the thickness of the cavity to be machined that needs to be roughly milled compared to the rough-machined end surface. The diameter of the clearance hole is larger than the diameter of the milling cutter for machining the cavity. The milling cutter for cavity machining enters the avoidance hole; Step 43, performing spiral milling layer by layer on the middle area of ​​the cavity to be processed; Step 44, performing plunge milling layer by layer on the four corners of the cavity to be processed.

[0027] Preferably, in step 43, when spiral milling is performed layer by layer on the middle area of ​​the cavity to be processed, the milling process of each layer is as follows: Step 431, as Figure 3 As shown, the cavity machining milling cutter moves along the Archimedean spiral trajectory to perform side milling; Step 432, let j = 1, where j represents the serial number of the monitoring moment when the middle area of ​​the cavity is processed; Step 433: The force sensor on the milling cutter bar for cavity machining monitors the cutting force, and each vibration sensor monitors the vibration amplitude, and transmits the monitoring data at the jth monitoring moment to the machine tool control system; Step 434 , when the vibration amplitude detected by the vibration sensor closest to the cavity machining milling cutter at the jth monitoring moment is greater than the amplitude threshold, the cutting depth of the cavity machining milling cutter is reduced by 5%; otherwise, the cutting depth remains unchanged; When the cutting force monitored by the force sensor on the cutter bar of the cavity machining milling cutter at the jth monitoring moment is greater than the critical value of the cutting force, the feed speed of the cavity machining milling cutter is reduced by 5%; otherwise, the feed speed remains unchanged; Specifically, the critical value of amplitude is 0.15 m / s², and the critical value of cutting force is 600 N; Step 435, let j=j+1; The cavity machining milling cutter proceeds to the jth monitoring moment along the Archimedean spiral trajectory based on the adjusted cutting depth and feed speed, and then enters step 433.

[0028] In this application, the cutting depth during spiral milling in the middle area of ​​the cavity is adjusted by monitoring the vibration amplitude of the vibration sensor closest to the cavity processing milling cutter, and the feed speed is adjusted by monitoring the cutting force of the force sensor on the cavity processing milling cutter arbor, so that the vibration amplitude of the processing position and the processing force of the tool are within the corresponding critical values ​​during the processing, preventing the vibration amplitude from being too large, thereby reducing the deformation caused by the processing process and improving the qualified rate of the end face cavity processing.

[0029] Preferably, in step 44, when the positions of the four corners of the cavity to be processed are plunge milled layer by layer, the plunge milling process for each corner and each layer is as follows: Step 441, determining the moving path of the plunge milling cutter for cavity machining; like Figure 4 As shown, starting from one end of the arc edge in each corner area, the cavity machining plunge milling cutter moves along the arc trajectory toward the other end to form a new arc edge; After that, the cavity machining plunge milling cutter is reset to one end of the new arc edge and the above process is repeated; In the above process, the cavity machining plunge milling cutter performs a downward plunge milling operation every time it moves to a tool position along the arc trajectory, and then lifts the tool to move to the next tool position. The spacing between two adjacent tool positions is 0.2~1mm. Step 442, let k = 1, where k represents the sequence number of the monitoring time when the four corner areas of the cavity are processed; Step 443: The force sensor on the cavity machining plunge milling cutter shank monitors the cutting force, and each vibration sensor monitors the vibration amplitude, and transmits the monitoring data at the kth monitoring moment to the machine tool control system; Step 444 , when the vibration amplitude detected by the vibration sensor closest to the cavity machining plunge milling cutter at the kth monitoring moment is greater than the amplitude threshold, the cutting depth of the cavity machining plunge milling cutter is reduced by 5%; otherwise, the cutting depth remains unchanged; When the cutting force monitored by the force sensor on the tool shank of the cavity machining plunge milling cutter at the kth monitoring moment is greater than the critical value of the cutting force, the feed speed of the cavity machining plunge milling cutter is reduced by 5%; otherwise, the feed speed remains unchanged; the feed speed of the cavity machining plunge milling cutter here refers to the speed of downward plunge milling; Specifically, the critical value of amplitude is 0.15 m / s², and the critical value of cutting force is 600 N; Step 445, set k=k+1; The cavity machining plunge milling cutter proceeds to the kth monitoring moment according to the tool path in step 441 based on the adjusted cutting depth and feed speed, and then enters step 443.

[0030] In this application, the cutting depth during milling at the four corners of the cavity is adjusted by monitoring the vibration amplitude of the vibration sensor closest to the cavity processing milling cutter, and the feed speed is adjusted by monitoring the cutting force of the force sensor on the tool shank of the cavity processing milling cutter, so that the vibration amplitude of the processing position and the processing force of the tool are within the corresponding critical values ​​during the processing, preventing the vibration amplitude from being too large, thereby reducing the deformation caused by the processing process and improving the qualified rate of the end face cavity processing.

[0031] Example 2: On the basis of embodiment 1, the shape-following support tooling includes a base plate 1, a support column 2 is fitted on the base plate 1 and can be lifted in the vertical direction, a support head 3 made of EAP material is fixedly arranged at the top end of the support column 2, EAP material is an electrically active polymer material, has special electrical properties and mechanical properties, after being subjected to electrical stimulation, produces deformation, and has good anti-seismic performance; the fitting relationship between the base plate 1, the support column 2 and the support head 3 is as shown in Figure 7 ; The inside of the support head 3 is provided with an electrode sheet 4, and the electrode sheet 4 forms a closed loop with a power supply and a voltage regulator.

[0032] The electrode sheet 4 adopts copper foil, has a square structure, a thickness of 0.1 millimeter, and a side length of 5 millimeters, the lead wire between the electrode sheet 4 and the voltage regulator adopts copper core, a diameter of 1 millimeter, and an insulating layer thickness of 0.5 millimeter, and the output range of the voltage regulator is 50-200V.

[0033] A plurality of vertical through holes for mounting the support column 2 are arranged on the base plate 1 of the application, a counterbore for mounting a nut 8 is arranged at the bottom end of the vertical through hole, the nut 8 is fixedly mounted in the counterbore, an outer thread matched with the nut 8 is arranged on the outer wall surface of the support column 2, and the support column 2 is screwed with the nut 8 after being inserted into the vertical through hole downward, and the lifting adjustment of the support column 2 is realized by rotating the support column 2.

[0034] Preferably, a silica gel layer 5 is bonded to the top end of the support head 3. The silica gel layer 5 directly contacts the workpiece blank, increases the contact flexibility, and reduces the surface scratches of the workpiece blank through flexible contact.

[0035] Preferably, a piezoelectric sensor 6 is arranged at the position where the support head 3 contacts the support column 2, and the piezoelectric sensor 6 is used to monitor the support force on the workpiece blank.

[0036] Preferably, a temperature sensor 7 is arranged at the position where the support head 3 contacts the support column 2, and the temperature sensor 7 is used to monitor the temperature of the support head 3.

[0037] The middle part of the support column 2 is provided with a threading hole for the connecting lead wire of the electrode sheet 4, the transmission line of the piezoelectric sensor 6 and the transmission line of the temperature sensor 7 to pass out.

[0038] In embodiment 2, the shape-following support tooling is used as follows: Firstly, the substrate 1 is placed on the machine tool workbench and fixed, the curvature of the surface to be supported in the workpiece blank is measured using a vernier caliper, the initial height of each support column 2 is determined, then the workpiece blank is supported above each support column 2, and then the two ends of the workpiece blank are fixed by a rigid clamp; the size of the supporting force is monitored by each piezoelectric sensor 6, when the supporting force is less than the minimum value in the set range, the output voltage of the voltage regulator connected to the electrode sheet 4 in the corresponding support head 3 is adjusted, the support head 3 is deformed to tightly press the workpiece blank upward, the supporting force is increased, until it is in the set range; when the supporting force is greater than the maximum value in the set range, the output voltage of the voltage regulator connected to the electrode sheet 4 in the corresponding support head 3 is adjusted, the support head 3 is deformed to retract downward, the supporting force is reduced, until it is in the set range; after the supporting forces monitored by all piezoelectric sensors 6 are in the set range, the adjustment of the workpiece blank by the conformal support tooling is completed, and subsequent milling processing can be carried out.

[0039] During the supporting process of the workpiece blank by the conformal support tooling, the heating of the electrode sheet 4 will cause the temperature of the support head 3 to rise, when the temperature of the support head 3 is too high, thermal deformation will occur, which will affect the supporting effect of the support head 3 on the workpiece blank, and further affect the processing effect. Therefore, in the present application, the temperature of the support head 3 is monitored by the temperature sensor 7, when the temperature of the support head 3 is too high, the corresponding electrode sheet 4 is powered off to reduce the influence of thermal deformation on the support of the workpiece blank.

[0040] The design of the conformal support tooling of the present application can support flat surfaces or curved surfaces, and has wide applicability. The support of the flat surface is as shown in Figure 5 The support of the curved surface is as shown in Figure 6

[0041] Although the specific embodiments of the present application have been described above with reference to the drawings, it is not a limitation on the present application, and those skilled in the art should understand that various modifications or variations made by those skilled in the art on the basis of the technical solutions of the present application without creative labor are still within the protection scope of the present application.​

Claims

1. A high-efficiency processing technology for thin-walled structural parts, characterized in that: The following steps are involved: Step 1: Use a conformal support fixture to support the workpiece blank above the machine tool worktable. The two ends of the workpiece blank are fixed by rigid clamps, with the end surface to be processed facing upwards. Step 2: Arrange a plurality of vibration sensors on the back side of the end face to be processed of the workpiece blank, wherein the arrangement density of the vibration sensors in the high stress area is greater than that in other areas; The vibration sensor is connected to the machine tool control system for communication, and the machine tool control system obtains the position of the vibration sensor and the monitored vibration amplitude signal; Step 3: Rough milling the upward end face using the unequally spaced layer cutting method. During the machining process, the machine tool control system adjusts the feed rate based on the cutting force monitored by the force sensor on the end face machining tool bar and adjusts the cutting depth based on the vibration amplitude monitored by the vibration sensor closest to the end face machining tool. Step 4: Rough milling is performed on the cavities on the end faces in sequence using a combination of spiral milling and plunge milling. During each cavity machining process, the machine tool control system adjusts the feed rate based on the cutting force monitored by the force sensor on the tool bar of the cavity machining tool, and adjusts the cutting depth based on the vibration amplitude monitored by the vibration sensor closest to the cavity machining tool. Step 5: Finish the end face and cavity according to the accuracy requirements.

2. The high-efficiency processing technology for thin-walled structural parts according to claim 1, characterized in that: In step 2, the high stress area refers to the area on the workpiece blank corresponding to the area with a wall thickness of less than 2 mm or a curvature radius of less than 10 mm in the thin-walled structural part.

3. The high-efficiency processing technology for thin-walled structural parts according to claim 1, characterized in that: Step 3 includes the following sub-steps: Step 31, according to the thickness of the end face to be processed that needs to be roughly milled off, the cutting depth of each layer and the number of milling layers are determined in a manner of increasing the milling depth layer by layer; Step 32: Milling is performed layer by layer. The milling process of each layer is as follows: Step 321 , the end surface machining tool is milled and cut along an S-shaped tool path; Step 322, let i = 1, i represents the serial number of the monitoring time during end surface processing; Step 323: The force sensor on the end machining tool shank monitors the cutting force, and each vibration sensor monitors the vibration amplitude, and transmits the monitoring data at the i-th monitoring moment to the machine tool control system; Step 324 , when the vibration amplitude detected by the vibration sensor closest to the end surface machining tool at the i-th monitoring moment is greater than the amplitude threshold, the cutting depth of the end surface machining tool is reduced by 5%; otherwise, the cutting depth remains unchanged; When the cutting force monitored by the force sensor on the tool bar of the end-face machining tool at the i-th monitoring moment is greater than the critical value of the cutting force, the feed speed of the end-face machining tool is reduced by 5%; otherwise, the feed speed remains unchanged; Step 325, let i=i+1; The end surface machining tool proceeds to the i-th monitoring moment by milling according to the S-shaped tool path based on the adjusted cutting depth and feed speed, and then enters step 323.

4. The high-efficiency processing technology for thin-walled structural parts according to claim 1, characterized in that: In step 4, the processing of each cavity includes the following sub-steps: Step 41: Based on the thickness of the cavity to be machined that needs to be rough-milled compared to the end face after rough machining, the cutting depth of each layer and the number of spiral milling layers are determined in a manner that the cutting depth increases layer by layer or the cutting depth of each layer is consistent. The cutting depth of each layer and the number of plunge milling layers are determined in a manner that the cutting depth of each layer is consistent. Step 42: Drilling a clearance hole at the center of the rough-machined end surface corresponding to the cavity. The drilling depth of the clearance hole is the thickness of the cavity to be machined that needs to be roughly milled compared to the rough-machined end surface. The milling cutter for cavity machining enters the avoidance hole; Step 43, performing spiral milling layer by layer on the middle area of ​​the cavity to be processed; Step 44, performing plunge milling layer by layer on the four corners of the cavity to be processed.

5. The high-efficiency processing technology for thin-walled structural parts according to claim 4, characterized in that: In step 43, when the middle area of ​​the cavity to be processed is subjected to spiral milling layer by layer, the milling process of each layer is as follows: Step 431 , the cavity machining milling cutter moves along the Archimedean spiral trajectory to perform side milling; Step 432, let j = 1, where j represents the serial number of the monitoring moment when the middle area of ​​the cavity is processed; Step 433: The force sensor on the milling cutter bar for cavity machining monitors the cutting force, and each vibration sensor monitors the vibration amplitude, and transmits the monitoring data at the jth monitoring moment to the machine tool control system; Step 434 , when the vibration amplitude detected by the vibration sensor closest to the cavity machining milling cutter at the jth monitoring moment is greater than the amplitude threshold, the cutting depth of the cavity machining milling cutter is reduced by 5%; otherwise, the cutting depth remains unchanged; When the cutting force monitored by the force sensor on the cutter bar of the cavity machining milling cutter at the jth monitoring moment is greater than the critical value of the cutting force, the feed speed of the cavity machining milling cutter is reduced by 5%; otherwise, the feed speed remains unchanged; Step 435, let j=j+1; The cavity machining milling cutter proceeds to the jth monitoring moment along the Archimedean spiral trajectory based on the adjusted cutting depth and feed speed, and then enters step 433.

6. The high-efficiency processing technology for thin-walled structural parts according to claim 4, characterized in that: In step 44, when the positions of the four corners of the cavity to be processed are plunge milled layer by layer, the plunge milling process for each corner and each layer is as follows: Step 441, determining the moving path of the plunge milling cutter for cavity machining; Starting from one end of the arc edge in each corner area, the cavity machining plunge milling cutter moves along the arc trajectory to the other end to form a new arc edge; After that, the cavity machining plunge milling cutter is reset to one end of the new arc edge and the above process is repeated; In the above process, the cavity machining plunge milling cutter performs a downward plunge milling operation every time it moves to a tool position along the arc trajectory, and then lifts the tool to move to the next tool position; Step 442, let k = 1, where k represents the sequence number of the monitoring time when the four corner areas of the cavity are processed; Step 443: The force sensor on the cavity machining plunge milling cutter shank monitors the cutting force, and each vibration sensor monitors the vibration amplitude, and transmits the monitoring data at the kth monitoring moment to the machine tool control system; Step 444 , when the vibration amplitude detected by the vibration sensor closest to the cavity machining plunge milling cutter at the kth monitoring moment is greater than the amplitude threshold, the cutting depth of the cavity machining plunge milling cutter is reduced by 5%; otherwise, the cutting depth remains unchanged; When the cutting force monitored by the force sensor on the tool shank of the cavity machining plunge milling cutter at the kth monitoring moment is greater than the critical value of the cutting force, the feed speed of the cavity machining plunge milling cutter is reduced by 5%; otherwise, the feed speed remains unchanged; Step 445, set k=k+1; The cavity machining plunge milling cutter proceeds to the kth monitoring moment according to the tool path in step 441 based on the adjusted cutting depth and feed speed, and then enters step 443.

7. The high-efficiency processing technology for thin-walled structural parts according to claim 1, characterized in that: The conformable support fixture comprises a base plate (1), a support column (2) is provided on the base plate (1) and can be lifted and lowered in a vertical direction, and a support head (3) made of EAP material is fixedly provided at the top end of the support column (2); An electrode sheet (4) is provided inside the support head (3), and the electrode sheet (4) forms a closed loop with the power supply and the voltage regulator.

8. The high-efficiency processing technology for thin-walled structural parts according to claim 7, characterized in that: A silicone layer (5) is bonded to the top of the support head (3).

9. The high-efficiency processing technology for thin-walled structural parts according to claim 7, characterized in that: A piezoelectric sensor (6) is provided at the position where the support head (3) contacts the support column (2).

10. The high-efficiency processing technology for thin-walled structural parts according to claim 7, characterized in that: A temperature sensor (7) is provided at the position where the support head (3) contacts the support column (2).

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