Active vibration suppression method of long overhanging cutter bar for precise turning of magnesium-aluminum alloy parts

Abstract

The invention relates to an active vibration suppression method for a long overhanging tool bar used for precise turning of magnesium-aluminum alloy parts. The method comprises the steps that a vibration mode of an order close to the vibration frequency of a turning tool bar is obtained through calculation; according to the obtained vibration mode data, the position of a response point with the maximum deformation of the cutter bar is determined; an aluminum plate with a round hole in the center is pasted to the position, coinciding with the response point, of the cutter bar; an active strain gauge with a hole in the center is glued to the position, coinciding with the response point, of the aluminum plate; adhering an ethylene-propylene-diene monomer rubber sheet with a hole in the center to the position, coinciding with the response point, of the active strain gauge; covering the positions of the aluminum plate, the active strain gauge and the EPDM rubber sheet except the open holes; an accelerometer is inserted into the holes of the aluminum plate, the active strain gauge and the ethylene propylene diene monomer and is adhered to the position of the response point; connecting the accelerometer, the active strain gauge and information acquisition and processing equipment; and after turning, according to the amplitude at the response point obtained through analysis, the active strain gauge generates flexible deformation which is equal to the amplitude at the response point and opposite to the amplitude at the response point, and flutter of the cutter bar is restrained.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical processing, and in particular relates to an active vibration suppression method for a long overhang tool bar used for precision turning of magnesium-aluminum alloy parts. Background Art

[0002] The redundant frame is a deep cavity structure and is made of magnesium-aluminum alloy. When a lathe is used to turn the redundant frame, a long overhang tool bar is required to meet the axial feed distance of turning. However, the rigidity of the long overhang tool bar is poor, and the rigidity of the parts is also poor when turning magnesium-aluminum alloy. Therefore, when turning the inner cavity of the redundant frame, the long overhang tool bar will vibrate, causing vibration marks and tool chipping in the deep cavity of the redundant frame. Therefore, the vibration problem of the long overhang tool bar has become one of the technical bottlenecks restricting the precision turning accuracy and surface integrity of magnesium-aluminum alloy parts. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides an active vibration suppression method for a long overhang tool bar used for precision turning of magnesium-aluminum alloy parts.

[0004] The above-mentioned object of the present invention is achieved by the following technical solutions:

[0005] A method for actively suppressing vibration of a long overhang tool bar for precision turning of magnesium-aluminum alloy parts comprises the following steps:

[0006] Step 1: Calculate and obtain a vibration mode of an order close to the vibration frequency of the turning tool bar according to the vibration frequency of the long overhang tool bar, the cutting parameters of the workpiece to be processed, and the material properties;

[0007] Step 2: According to the vibration mode data finally obtained in step 1, determine the response point position Ai where the deformation of the long overhanging tool bar is the largest, where i=1 or 2 or 3;

[0008] Step 3: Paste the aluminum plate with a circular hole in the center onto the long overhanging shank, so that the center of the circular hole in the center of the aluminum plate coincides with the response point position Ai;

[0009] Step 4: Glue the active strain gauge with the central opening to the aluminum plate, and the flexural deformation direction of the active strain gauge is consistent with the rod body of the long overhanging knife rod, and the opening circle of the active strain gauge coincides with the response point position Ai;

[0010] Step 5: Paste the EPDM rubber sheet with a central hole onto the active strain gauge, and the center of the hole of the EPDM rubber sheet coincides with the response point Ai;

[0011] Step 6: Use silicone rubber to cover the exposed parts of the aluminum plate, active strain gauge, and EPDM rubber sheet except the openings;

[0012] Step 7: Insert the accelerometer into the aluminum plate, active strain gauge, and EPDM rubber opening in a clearance fit manner, and stick the accelerometer to the response point Ai;

[0013] Step 8: Connect the accelerometer, active strain gauge and information acquisition and processing equipment, and connect the information acquisition and processing equipment to the computer to ensure data transmission; turn on the information acquisition and processing equipment, open the equipment signal analysis software on the computer, debug the serial port, and ensure that data transmission is effective;

[0014] Step nine: start the deep cavity turning process of the workpiece; after turning starts, the information acquisition and processing equipment collects the acceleration signal transmitted by the accelerometer and transmits it to the software of the corresponding computer device, uses the software to analyze the acceleration signal, and uses the control algorithm to calculate the amplitude at the response point position Ai of the long overhang turning tool rod 1 in real time, and applies a signal to the active strain gauge to make the active strain gauge produce a flexible deformation with the same amplitude and opposite direction as the response point position Ai, so as to achieve real-time offset of the chatter amplitude at the response point position Ai of the long overhang turning tool rod, and suppress the chatter of the long overhang turning tool rod.

[0015] Moreover, step one is specifically as follows:

[0016] The first three-order modal analysis of the long overhang turning tool bar 1 is performed through simulation software to obtain its first three-order vibration frequencies and vibration modes; the vibration frequency of the workpiece during turning is calculated through the cutting parameters and material properties of the workpiece; by comparing the vibration frequency of the workpiece with the first three-order modes of the long overhang tool bar 1, the order of the first three-order modes that are relatively close to the vibration frequency is determined, and the vibration mode of this order is saved.

[0017] Moreover, in step three, the thickness of the aluminum plate is 0.5 mm.

[0018] Moreover, in step 5, the thickness h of the EPDM rubber sheet is: 2 mm < h < 5 mm.

[0019] The advantages and positive effects of the present invention are:

[0020] (1) The present invention uses the flexible deformation generated by the active strain gauge to offset the vibration amplitude of the long overhanging tool bar, thereby realizing real-time online vibration detection and suppression.

[0021] (2) The present invention uses simulation software to locate the response point Ai of the long overhang turning tool bar, and uses active strain gauges to eliminate the chatter at this position, which can suppress the occurrence of chatter from the source, with significant effect.

[0022] (3) The present invention uses an aluminum sheet with high ductility as the substrate of the strain gauge, so that the flexural deformation generated by the active strain gauge can act on the long overhanging tool rod to the maximum extent, thereby enhancing the effect of suppressing chatter.

[0023] (4) In the present invention, quick-drying glue is used to firmly bond the contact surfaces of the knife rod and the aluminum plate, the aluminum plate and the active strain gauge, and the active strain gauge and the EPDM rubber sheet to form a rigid connection, thereby enhancing the effect of suppressing chatter. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the assembly of the present invention;

[0025] Figure 2 It is a schematic diagram of the application of the present invention;

[0026] Figure 3 It is a schematic diagram of the principle of the present invention;

[0027] Figure 4 This is a schematic diagram of the structure of the long overhang turning tool bar of the present invention;

[0028] Figure 5 This is a schematic diagram of the aluminum plate structure of the present invention;

[0029] Figure 6 This is a schematic diagram of the structure of the active strain gauge of the present invention;

[0030] Figure 7 This is a schematic diagram of the structure of the EPDM rubber sheet of the present invention;

[0031] Figure 8 It is a structural schematic diagram of a redundant frame of a processing object according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The structure of the present invention is further described below with reference to the accompanying drawings and by way of examples. It should be noted that the present examples are descriptive rather than restrictive.

[0033] An active vibration suppression method for long overhang toolholders used in precision turning of magnesium and aluminum alloy parts, see Figure 1-Figure 8 , the invention point is that it comprises the following steps:

[0034] Step 1: Perform the first three-order modal analysis on the long overhang turning tool bar 1 through simulation software to obtain its first three-order vibration frequencies and vibration modes; calculate the vibration frequency of the workpiece during turning by the cutting parameters and material properties of the workpiece; by comparing the vibration frequency of the workpiece with the first three-order modes of the long overhang tool bar 1, determine the order of the first three-order modes that are relatively close to the vibration frequency, and save its vibration mode of this order.

[0035] Step 2: According to the vibration mode data finally obtained in step 1, determine the response point position Ai (i=1 or 2 or 3) with the maximum deformation. The i in Ai represents the order of the formation, for example, A2 is the response point position in the 2nd order mode formation.

[0036] Step 3: Use quick-drying glue to stick the 0.5mm thick aluminum plate 2 with a circular hole in the center to the long overhanging tool rod 1, and make the center of the central circular hole of the aluminum plate 2 coincide with the response point position Ai. Note that the two surfaces of the aluminum plate 2 should be smooth. The quick-drying glue is used to achieve a rigid connection between the aluminum plate 2 and the turning tool rod 1, and the quick-drying glue should be applied to all the pasting surfaces. The aluminum plate 2 is selected because a metal with good ductility and low cost needs to be selected.

[0037] Step 4: Use quick-drying glue to stick the active strain gauge 3 to the aluminum plate 2. When sticking, ensure that the flexible deformation direction of the active strain gauge 3 is consistent with the rod body of the long overhanging knife rod 1, and pay attention to the front and back sides of the strain gauge 3; a hole should be opened in the center of the active strain gauge 3, and the hole size should be larger than the maximum outer diameter of the accelerometer 5; when sticking the active strain gauge 3, the center of the hole should coincide with the response point position Ai.

[0038] Step 5: Use quick-drying glue to stick the EPDM rubber sheet 4 to the active strain gauge 3. The thickness h of the EPDM rubber sheet 4 should satisfy 2mm<h<5mm to ensure that the EPDM rubber sheet 4 can protect the strain gauge 3 from being scratched by chips and cannot hinder the effective flexural deformation of the active strain gauge 3. A hole should be opened in the center of the EPDM rubber sheet 4, and the size of the hole should be larger than the maximum outer diameter of the accelerometer 5. When sticking the EPDM rubber sheet 4, the center of the hole should coincide with the response point position Ai.

[0039] Step six: Use silicone rubber to cover the exposed positions of the aluminum plate 2, the active strain gauge 3, and the EPDM rubber sheet 4 except the openings, so as to protect the active strain gauge 3 and the EPDM rubber 4, and further strengthen the bonding strength between the shank 1 and the aluminum plate 2, the aluminum plate 2 and the active strain gauge 3, and the active strain gauge 3 and the EPDM rubber 4.

[0040] Step 7: In the opening positions of the aluminum plate 2, the active strain gauge 3, and the EPDM rubber 4, the accelerometer 5 is pasted to the response point position Ai using quick-drying glue.

[0041] Step 8: Connect the accelerometer 5 and active strain gauge 3 to the information acquisition and processing device (NI signal pad device), and connect the information acquisition and processing device (NI signal pad device) to the computer to ensure data transmission. Turn on the information acquisition and processing device (NI signal pad device), open the device signal analysis software on the computer, debug the serial port, and ensure that the data transmission is effective.

[0042] Step 9: After completing the above steps, start the deep cavity turning process of the workpiece (such as the redundant frame). After turning, the information acquisition and processing equipment (NI signal pad equipment) collects the acceleration signal transmitted by the accelerometer 5 and transmits it to the software of the corresponding computer equipment. The acceleration signal is analyzed by the software, and the amplitude at the response point position Ai of the long overhang turning tool rod 1 is calculated in real time by the control algorithm, and the signal is applied to the active strain gauge 3, so that the active strain gauge 3 produces a flexural deformation equal to the amplitude at the response point position Ai and in the opposite direction, thereby achieving real-time offset of the chatter amplitude at the response point position Ai of the long overhang turning tool rod 1. In this way, the chatter of the long overhang turning tool rod 1 is suppressed, and stable turning of the redundant frame deep cavity is achieved.

[0043] The working principle of the above-mentioned active strain gauge is as follows: when the tool vibrates and deforms at point A (strain force exists locally), the vibration signal of this point is collected and the suppression signal is transmitted to the strain gauge pasted at point A through an algorithm. The strain gauge will generate a strain force (flexible force) opposite to the vibration deformation of point A, offset the vibration strain of point A, stabilize point A, and achieve vibration suppression.

[0044] The invention can be used in the mechanical processing fields of aerospace, chemical industry, water conservancy, electric power and other industries, especially in the field of deep cavity precision turning of magnesium-aluminum alloy parts, and has a very broad prospect for promotion and application.

[0045] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. An active vibration suppression method for a long overhang tool bar used for precision turning of magnesium-aluminum alloy parts, characterized in that: The steps include: Step 1: Calculate and obtain a vibration mode of an order close to the vibration frequency of the turning tool bar according to the vibration frequency of the long overhang tool bar, the cutting parameters of the workpiece to be processed, and the material properties; Step 2: According to the vibration mode data finally obtained in step 1, determine the response point position Ai where the deformation of the long overhanging tool bar is the largest, where i=1 or 2 or 3; Step 3: Paste the aluminum plate with a circular hole in the center onto the long overhanging shank, so that the center of the circular hole in the center of the aluminum plate coincides with the response point position Ai; Step 4: Glue the active strain gauge with the central opening to the aluminum plate, and the flexural deformation direction of the active strain gauge is consistent with the rod body of the long overhanging knife rod, and the opening circle of the active strain gauge coincides with the response point position Ai; Step 5: Paste the EPDM rubber sheet with a central hole onto the active strain gauge, and the center of the hole of the EPDM rubber sheet coincides with the response point Ai; Step 6: Use silicone rubber to cover the exposed parts of the aluminum plate, active strain gauge, and EPDM rubber sheet except the openings; Step 7: Insert the accelerometer into the aluminum plate, active strain gauge, and EPDM rubber opening in a clearance fit manner, and stick the accelerometer to the response point Ai; Step 8: Connect the accelerometer, active strain gauge and information acquisition and processing equipment, and connect the information acquisition and processing equipment to the computer to ensure data transmission; turn on the information acquisition and processing equipment, open the equipment signal analysis software on the computer, debug the serial port, and ensure that data transmission is effective; Step nine: start the deep cavity turning process of the workpiece; after turning starts, the information acquisition and processing equipment collects the acceleration signal transmitted by the accelerometer and transmits it to the software of the corresponding computer device, uses the software to analyze the acceleration signal, and uses the control algorithm to calculate the amplitude at the response point position Ai of the long overhang turning tool rod 1 in real time, and applies a signal to the active strain gauge to make the active strain gauge produce a flexible deformation with the same amplitude and opposite direction as the response point position Ai, so as to achieve real-time offset of the chatter amplitude at the response point position Ai of the long overhang turning tool rod, and suppress the chatter of the long overhang turning tool rod.

2. The active vibration suppression method for a long overhang tool bar used for precision turning of magnesium-aluminum alloy parts according to claim 1 is characterized in that: Step 1 is as follows: The first three-order modal analysis of the long overhang turning tool bar is performed through simulation software to obtain its first three-order vibration frequencies and vibration modes; the vibration frequency of the workpiece during turning is calculated through the cutting parameters and material properties of the workpiece; by comparing the vibration frequency of the workpiece with the first three-order modes of the long overhang tool bar, the order of the first three-order modes that are relatively close to the vibration frequency is determined, and the vibration mode of this order is saved.

3. The active vibration suppression method for a long overhang tool bar used for precision turning of magnesium-aluminum alloy parts according to claim 1 is characterized in that: In step 3, the thickness of the aluminum plate is 0.5 mm.

4. The active vibration suppression method for a long overhang tool bar used for precision turning of magnesium-aluminum alloy parts according to claim 1 is characterized in that: In step 5, the thickness h of the EPDM rubber sheet is: 2mm<h<5mm.

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