CN112893553B - Double-layer capillary tube bending device and method for removing residual stress by vibration - Google Patents

Abstract

The invention relates to a double-layer capillary tube bending device and method for removing residual stress by vibration. The novel bent pipe clamp is used, the clamp is simple in structure and good in stability, and can be well matched with a detection part for removing residual stress through oscillation; a new detection and implementation system for removing residual stress by vibration is also designed; by utilizing the characteristic that the ultrasonic wave propagates along the capillary, when residual stress exists in the capillary, the residual stress can affect the propagation of the ultrasonic wave, so that the received ultrasonic wave signal is changed; the method comprises the steps of simultaneously measuring a plurality of angles, measuring the measurement results under different vibration frequencies and standard signals without internal stress, and calculating the Mahalanobis distance, so that the optimal vibration frequency of each angle can be obtained, then vibrating according to the optimal frequency, the effect of removing residual stress can be improved, the time is saved, and the production efficiency is improved.

Description

A double-layer capillary bending device and method for removing residual stress by vibration

technical field

The invention relates to the field of capillary processing, in particular to a double-layer capillary bending device and method for removing residual stress by vibration.

Background technique

As a throttling component in the air conditioner, the capillary has the functions of throttling and reducing pressure. In order to meet the installation requirements, both ends of the capillary need to be bent. Application number CN201210123271.7 discloses a capillary bending device, including a frame body, a workbench arranged on the frame body, a driving device, a control device for controlling the driving device, and a winding device arranged on the workbench and a fixing device for fixing the capillary to be processed; the winding device includes a main shaft connected to the driving device, a turntable driven by the main shaft, and the main shaft passes through the turntable, and the turntable is provided with A material-setting column, an accommodating space for accommodating the capillary to be processed is formed between the material-setting column and the main shaft.

Application number CN201922392563.0 discloses an efficient and adjustable bending device for double pipe clamp processing, including a main body, a base, a workbench, a slider, a connector, a reducer, a motor, a backing plate, a punch, a die and Two sets of fixing devices, the main body is installed in the second half of the base, the motor is installed in the front half of the top of the main body, the output end of the motor is connected to the reducer, the output end of the reducer is connected to the top of the connector, the bottom of the connector is connected to the top of the slider, and the slider is connected to the bottom of the connector. The bottom end of the block is connected to the punch, and the workbench is installed in the front half of the base; it also includes a support plate and an emergency latch. A cavity is arranged in the workbench, a support block is arranged on the rear wall of the cavity, and a There is a through hole, the emergency latch includes a handle and a plunger, and the support plate is installed on the top of the support block and the plunger.

The traditional bending process still has a large internal stress in the capillary after bending. If you want to better remove this stress, you generally need high-temperature treatment. High-temperature treatment is inefficient and time-consuming, and rapid production is not used.

Vibration is a better way to remove residual stress. Application number CN201911217460.9 discloses an intelligent high-frequency vibration aging system for eliminating residual stress of small-sized components. The system consists of a PC, a signal generator, a power driver, an electromagnetic exciter, a high-frequency vibration energy amplification device, pads, strain gauges, and a dynamic strain gauge; the PC controls the signal generator to output a high-frequency excitation signal, which is passed through After the power driver is amplified, it is input to the electromagnetic exciter, and then drives the electromagnetic exciter to generate high-frequency vibration; small-sized components are installed on the upper surface of the workbench; strain gauges are pasted at the peak residual stress of small-sized components; Under the axial resonant frequency of the energy amplification device, high-frequency vibration aging treatment is performed on small-sized components. But for bent pipes, different bending angles correspond to different optimal frequencies, so the traditional method needs to be improved.

Contents of the invention

In view of the above, in order to solve the above problems, a double-layer capillary pipe bending device is provided. The pipe bending fixture includes a base plate, a guide clip, a main clip, a main clip seat, a wheel mold and a wheel mold shaft; the guide clip is in the shape of a cuboid, and the bottom surface is fixed on the On the bottom plate, the side is provided with a strip-shaped semi-circular groove matching the capillary along the horizontal direction, and the side wall of the capillary can match the semi-circular groove of the guide clip; the shape of the wheel mold is a closed shape formed by a semi-circular arc and a frame composed of three straight lines along the The object formed by translation in the vertical direction; the side of the wheel mold includes three planes and a semi-cylindrical surface, wherein the two planes and the semi-cylindrical surface between them are provided with strip-shaped semi-circular grooves that match the capillary along the horizontal direction; the capillary The side wall of the wheel mold can be matched with the semi-circular groove of the wheel mold; the wheel mold shaft is arranged along the axis of the semi-cylindrical surface so that the wheel mold can rotate around the wheel mold axis; the shape of the main clip is the same as that of the guide clip, and the main clip passes through the main The clamp seat is fixed on the plane side wall of the wheel mold, and the side of the main clamp in contact with the wheel mold is provided with a strip-shaped semicircular groove matching with the capillary along the horizontal direction, so that the wheel mold and the two semicircular grooves of the main clamp form a Cylindrical hole;

The rotation range of the wheel mold has two endpoints. When turning to the first end, one side of the main clip contacts one side of the guide clip. At this time, the two semicircular grooves of the wheel mold and the main clip form a cylindrical hole and a bar on the side of the guide clip. The two semicircular grooves are coaxial; when turning to the second end, the other plane side wall of the wheel mold is in contact with one side of the guide clip, so that the two semicircular grooves of the wheel mold and the guide clip form a cylindrical hole, and the wheel mold and the guide clip The cylindrical hole formed by the two semicircular grooves of the wheel mold and the main clamp is parallel to the cylindrical hole formed by the two semicircular grooves of the main clamp;

There are two strip-shaped semicircular grooves on the side of the guide clip, the main clip and the wheel mold in the vertical direction, and the radii are unequal.

A double-layer capillary tube bending device that uses vibration to remove residual stress, including a bending fixture, and also includes a main controller, a detection ultrasonic driving module, a vibration loading driving module and a bending loading driving module, and is characterized in that:

The main controller connects and detects the ultrasonic driving module, the vibration loading driving module and the bending loading driving module;

The ultrasonic detection driving module is connected with a transmitting probe and a collecting probe, the transmitting probe is used for transmitting ultrasonic waves, the ultrasonic waves emitted by the transmitting probe propagate along the extension direction of the capillary, and the collecting probe is used for collecting the ultrasonic waves emitted from the transmitting probe;

The emission probe and the collection probe are respectively arranged at the two ends of the capillary;

The vibration loading drive module is connected to the function generator and the echo collector, the function generator is used to generate and send frequency sweep signals, the function generator is connected to the electromagnetic oscillator, and the electromagnetic oscillator performs frequency sweep oscillation according to the frequency sweep signal sent by the function generator; Both the oscillator and the echo collector are arranged on the main clip, and are arranged on the opposite side of the surface where the main clip is in contact with the capillary, so that the oscillation emitted by the electromagnetic oscillator can be transmitted to the capillary; the echo collector collects from the capillary The reflected oscillating signal;

The bending loading drive module is connected with an angle encoder and a loading motor; the angle encoder is used to detect the rotation angle of the wheel mold, and the loading motor is used to control the rotation of the wheel mold.

The emission probe and the collection probe have the same structure, including an end face circular plate, and the end face circular plate is provided with an annular groove, which is used to put the end face of the capillary into; the outer side of the groove is provided with 8 ultrasonic probes arranged in a circular arrangement at equal intervals. Transducer; so that the 8 transducers of the transmitting probe at one end emit 8 ultrasonic waves, and the 8 ultrasonic transducers of the collecting probe at the other end correspond to collect 8 transmitted vibration signals, and the 8 channels of vibration that will be collected by the collecting probe The strength of the signal is fed back to the main controller.

A method for removing residual stress using the double-layer capillary bend device, comprising the steps of:

Step 1, use the bending fixture to bend the capillary into multiple gradient angles, respectively 20°, 40°, 60°, 80°, 100°, 120°, 140°, 160°, 180°; The bent capillary is removed and annealed to remove the stress generated during the bending process;

Step 2, reinstall the annealed capillary on the elbow fixture, and install the emission probe and the collection probe. The emission probe and the collection probe are respectively installed at both ends of the capillary; the emission probe is driven by 8 channels of ultrasound with the same intensity Measure the intensity of the 8-way vibration signal collected by the capillary corresponding to the annealed probe, and use the 8-way collected signal as the reference signal R _i =[r ₁ ,r ₂ ,…,r ₈ ], where i is 1~9, corresponding to Different bending angles, that is, each bending angle corresponds to a set of reference signals;

Step 3, install the new unbent capillary on the bend fixture and bend to angles of 20°, 40°, 60°, 80°, 100°, 120°, 140°, 160°, 180° , at an angle, control the vibration loading drive module to perform frequency sweep oscillation, and at the same time detect whether the signal strength I of the echo collector is stable, if I produces a step change, it means that the capillary installation is unstable and needs to be re-measured; Under the driving of 8 channels of ultrasonic waves with the same intensity, measure the intensity of the 8 channels of vibration signals of the annealed capillary corresponding to the collection probe, and use the signals collected by 8 channels as the detection signal Q _ij =[q _1j ,q _2j , …,q _8j ], where j is the frequency of the frequency sweep during detection, i is 1 to 9, corresponding to different bending angles, that is, each oscillation frequency and a bending angle correspond to a group of detection signals, i×j in total group signal;

Step 4, group the i×j group of detection signals in step 3 according to i, and divide them into 9 groups, and calculate the Mahalanobis distance between the j group of detection signals in each group and the corresponding reference signal of i; and from The group corresponding to each i screens out a j with the smallest Mahalanobis distance; get 9 j, respectively J ₁ , J ₂ ,..., J ₉ ; these 9 J are the best corresponding from 20°-180° Oscillation frequency;

Step 5, take the angle of 0-180° as the abscissa and the frequency as the ordinate, (20°, J ₁ ), (40°, J ₂ ), (60°, J ₃ ), (80°, J ₄ ), (100°, J ₅ ), (120°, J ₆ ), (140°, J ₇ ), (160°, J ₈ ), (180°, J ₉ ) fill in the coordinate chart, and then connect Form a curve, which is the oscillation drive curve;

Step 6, install the capillary to be bent on the bending fixture, control the loading motor to perform bending loading, and then control the vibration loading drive module to oscillate the frequency corresponding to the angle on the driving curve according to the bending angle detected by the angle encoder Oscillate until it is bent to the required angle, and continue to oscillate for a certain period of time at the frequency corresponding to the end point angle on the oscillation drive curve at the end point angle to complete the work of removing the residual stress.

The beneficial effects of the present invention are:

The present invention uses a new pipe bend fixture, which has a simple structure and good stability, and can be used in good cooperation with vibration removal of residual stress and detection components; a new detection and implementation system of vibration removal of residual stress is also designed ;Using the characteristics of ultrasonic waves propagating along the capillary, when there is residual stress in the capillary, it will affect the propagation of ultrasonic waves, so that the received ultrasonic signal changes; Simultaneously measure from multiple angles, and measure the measured value at different vibration frequencies Calculate the Mahalanobis distance between the result and the standard signal without internal stress, so that the optimal vibration frequency of each angle can be obtained, and then vibrate according to the optimal frequency, which can improve the effect of removing residual stress, save time and improve production efficiency.

Description of drawings

The accompanying drawings, which are included to provide a further understanding of the disclosed subject matter, are incorporated in and constitute a part of this specification. The drawings also illustrate implementations of the disclosed subject matter and, together with the detailed description, serve to explain implementation principles of the disclosed subject matter. No attempt has been made to reveal more structural detail than is necessary for a fundamental understanding of the disclosed subject matter and its various ways of practicing it.

Fig. 1 is a schematic structural view of a pipe bend fixture of the present invention;

Fig. 2 is a schematic diagram of the control structure of the pipe bending fixture of the present invention;

Fig. 3 is the structural representation of different states of the pipe bend clamp of the present invention

Figure 4 is a schematic diagram of the structure of the transmitting probe and the collecting probe and the polar coordinate display of the signal strength detected by the receiving probe.

Detailed ways

The advantages, characteristics, and means for achieving the object of the present invention will be clarified by the accompanying drawings and detailed descriptions that follow.

Example 1:

In conjunction with Fig. 1, a double-layer capillary tube bending fixture, the bending fixture includes a bottom plate, a guide clip 11, a main clip 12, a main clip seat 13, a wheel mold 14 and a wheel mold shaft 15; the guide clip 11 is in the shape of a cuboid, and the bottom surface is fixed On the bottom plate, a bar-shaped semicircular groove matching the capillary is arranged on the side along the horizontal direction, and the side wall of the capillary can match the semicircular groove of the guide clip 11; the shape of the wheel mold 14 is formed by a frame composed of a semicircular arc and three straight lines The closed shape is translated along the vertical direction to form an object; the side of the wheel mold 14 includes three planes and a semi-cylindrical surface, wherein the two planes and the semi-cylindrical surface between them are provided with strips that cooperate with the capillary in the horizontal direction. Semicircular groove; The side wall of capillary can be matched with the semicircular groove of wheel mold 14; Wheel mold axle 15 is provided with along the axis of semicylindrical surface so that wheel mold 14 can rotate around wheel mold axle 15; The shape and guide of main clip 12 The shape of the clamps 11 is the same, the main clamp 12 is fixed on the side wall of the wheel mold 14 through the main clamp seat 13, and the side of the main clamp 12 contacting the wheel mold 14 is provided with a strip-shaped semicircle that is matched with the capillary along the horizontal direction. Groove, so that two semicircular grooves of the wheel mold 14 and the main clip 12 form a cylindrical hole;

The rotation range of the wheel mold 14 has two endpoints. When rotating to the first end, one side of the main clip 12 is in contact with one side of the guide clip 11. At this time, the two semicircular grooves of the wheel mold 14 and the main clip 12 form a cylindrical hole and The strip-shaped semicircular grooves on the side of the guide clip 11 are coaxial; when turning to the second end, the other plane side wall of the wheel mold 14 is in contact with one side of the guide clip 11, so that the wheel mold 14 and the two semicircular grooves of the guide clip 11 are formed A cylindrical hole, and the cylindrical hole formed by the two semicircular grooves of the wheel mold 14 and the guide clip 11 is parallel to the cylindrical hole formed by the two semicircular grooves of the wheel mold 14 and the main clip 12;

The strip-shaped semicircular grooves on the guide clip 11, the main clip 12 and the wheel mold 14 sides are two in the vertical direction, and the radii are unequal.

Example 2:

Combined with Figures 2-4, a double-layer capillary tube bending device that uses vibration to remove residual stress, including a bending fixture, also includes a main controller, a detection ultrasonic drive module, a vibration loading drive module, and a bending loading drive module. Its features in:

The main controller connects and detects the ultrasonic driving module, the vibration loading driving module and the bending loading driving module;

Detecting the ultrasonic drive module is connected with a transmitting probe 21 and a collecting probe 22, the transmitting probe 21 is used for transmitting ultrasonic waves, the ultrasonic waves sent by the transmitting probe 21 propagate along the extension direction of the capillary, and the collecting probe 22 is used for collecting the emitted ultrasonic waves from the transmitting probe 21. ultrasound;

The emission probe 21 and the collection probe 22 are respectively arranged at both ends of the capillary;

The vibration loading drive module is connected to a function generator and an echo collector 24, the function generator is used to send a frequency sweep signal, the function generator is connected to an electromagnetic oscillator 23, and the electromagnetic oscillator 23 performs frequency sweep oscillation according to the frequency sweep signal sent by the function generator The electromagnetic oscillator 23 and the echo collector 24 are all arranged on the main clip 12, and are arranged on the opposite side of the surface where the main clip 12 is in contact with the capillary, so that the vibration emitted by the electromagnetic oscillator 23 can be transmitted to the capillary; The echo collector 24 collects the oscillation signal reflected from the capillary;

The bending loading drive module is connected with an angle encoder and a loading motor; the angle encoder is used to detect the rotation angle of the wheel mold 14, and the loading motor is used to control the rotation of the wheel mold 14.

The transmitting probe 21 and the collecting probe 22 have the same structure, including an end face disc 31, and the end face disc 31 is provided with an annular groove 32, which is used to put the end face of the capillary into; the outer side of the groove is provided with equidistant annular grooves. 8 ultrasonic transducers 33 are arranged; so that the 8 transducers of the transmitting probe 21 at one end emit 8 ultrasonic waves, and the 8 ultrasonic transducers 33 of the collecting probe 22 at the other end correspondingly collect 8 transmitted vibration signals , the collection probe 22 feeds back the intensity of the collected 8 vibration signals to the main controller.

A method for removing residual stress using the double-layer capillary bend device, comprising the steps of:

Step 1, use the bending fixture to bend the capillary into multiple gradient angles, respectively 20°, 40°, 60°, 80°, 100°, 120°, 140°, 160°, 180°; The bent capillary is removed and annealed to remove the stress generated during the bending process;

Step 2, reinstall the annealed capillary on the elbow fixture, and install the emission probe and the collection probe 22, the emission probe 21 and the collection probe 22 are respectively installed at the two ends of the capillary; Driven by ultrasonic waves, measure the intensity of the 8-channel vibration signal of the annealed capillary corresponding to the collection probe 22, and use the signals collected by the 8-channel as the reference signal R _i =[r ₁ ,r ₂ ,...,r ₈ ], where i is 1 to 9, corresponding to different bending angles, that is, each bending angle corresponds to a set of reference signals;

Step 3, install the new unbent capillary on the bend fixture and bend to angles of 20°, 40°, 60°, 80°, 100°, 120°, 140°, 160°, 180° , at an angle, control the vibration loading drive module to perform frequency sweep oscillation, and simultaneously detect whether the signal strength I of the echo collector 24 is stable, if I produces a step change, this shows that the capillary installation is unstable and needs to be re-measured; While sweeping the frequency, the transmitting probe 21 is driven by 8 channels of ultrasound with the same intensity to measure the intensity of the annealed capillary corresponding to the 8 channels of vibration signals of the collecting probe 22, and the signals collected by the 8 channels are used as the detection signal Q _ij =[q _1j , q _2j ,…,q _8j ], where j is the scanning frequency of the vibration-loaded drive module during detection, i is 1 to 9, corresponding to different bending angles, that is, each oscillation frequency and a bending angle correspond to a group Detection signals, a total of i×j groups of signals;

Step 4, grouping the i×j group of detection signals in step 3 according to the same i, and dividing them into 9 groups, and calculating the Mahalanobis distance between the j group of detection signals in each group and the reference signal corresponding to i; And select a j with the smallest Mahalanobis distance from the group corresponding to each i; get 9 js, which are J ₁ , J ₂ ,..., J ₉ ; these 9 Js are from 20°-180° Optimum oscillation frequency of the vibration-loaded drive module;

Step 5, take the angle of 0-180° as the abscissa and the frequency as the ordinate, (20°, J ₁ ), (40°, J ₂ ), (60°, J ₃ ), (80°, J ₄ ), (100°, J ₅ ), (120°, J ₆ ), (140°, J ₇ ), (160°, J ₈ ), (180°, J ₉ ) fill in the coordinate chart, and then connect Form a curve, which is the oscillation drive curve;

Step 6, install the capillary to be bent on the bending fixture, control the loading motor to perform bending loading, and then control the vibration loading drive module to oscillate the frequency corresponding to the angle on the driving curve according to the bending angle detected by the angle encoder Oscillate until it is bent to the required angle, and continue to oscillate for a certain period of time at the frequency corresponding to the end point angle on the oscillation drive curve at the end point angle to complete the work of removing the residual stress.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (3)

1. The utility model provides an utilize vibration to get rid of residual stress's double-deck capillary swan neck system, includes return bend anchor clamps, main control unit, detects supersound drive module, vibration loading drive module and the loading drive module of buckling, its characterized in that:

the pipe bending clamp comprises a bottom plate, a guide clamp (11), a main clamp (12), a main clamp seat (13), a wheel mold (14) and a wheel mold shaft (15); the guide clamp (11) is in a cuboid shape, the bottom surface of the guide clamp is fixed on the bottom plate, the side surface of the guide clamp is provided with a strip-shaped semicircular groove matched with the capillary tube along the horizontal direction, and the side wall of the capillary tube can be matched with the semicircular groove of the guide clamp (11); the wheel mold (14) is an object formed by translating along the vertical direction in a closed shape formed by a frame consisting of a semicircular arc and three straight lines; the side surface of the wheel mould (14) comprises three planes and a semi-cylindrical surface, wherein strip-shaped semi-circular grooves matched with the capillary tubes are arranged on the two planes and the semi-cylindrical surface between the two planes along the horizontal direction; the side wall of the capillary can be matched with the semicircular groove of the wheel die (14); a wheel mould shaft (15) is arranged along the axis of the semi-cylindrical surface, so that the wheel mould (14) can rotate around the wheel mould shaft (15); the shape of the main clamp (12) is the same as that of the guide clamp (11), the main clamp (12) is fixed on the side wall of the plane of the wheel mold (14) through a main clamp seat (13), and strip-shaped semicircular grooves matched with the capillary tubes are arranged on the side face, in contact with the wheel mold (14), of the main clamp (12) along the horizontal direction, so that a cylindrical hole is formed by the wheel mold (14) and the two semicircular grooves of the main clamp (12);

the rotation range of the wheel mold (14) is provided with two end points, one side of the main clamp (12) is contacted with one side of the guide clamp (11) when the wheel mold (14) rotates to the first end, and at the moment, two semicircular grooves of the wheel mold (14) and the main clamp (12) form a cylindrical hole which is coaxial with the strip-shaped semicircular groove on the side surface of the guide clamp (11); when the wheel mold (14) rotates to the second end, the other plane side wall of the wheel mold (14) is contacted with one side of the guide clamp (11), so that the wheel mold (14) and the two semicircular grooves of the guide clamp (11) form a cylindrical hole, and the cylindrical hole formed by the wheel mold (14) and the two semicircular grooves of the guide clamp (11) is parallel to the cylindrical hole formed by the wheel mold (14) and the two semicircular grooves of the main clamp (12);

the two strip-shaped semicircular grooves on the side surfaces of the guide clamp (11), the main clamp (12) and the wheel die (14) are arranged in the vertical direction, and the radiuses of the two strip-shaped semicircular grooves are unequal;

the main controller is connected with the detection ultrasonic driving module, the vibration loading driving module and the bending loading driving module;

the detection ultrasonic driving module is connected with a transmitting probe (21) and a collecting probe (22), the transmitting probe (21) is used for transmitting ultrasonic waves, the ultrasonic waves transmitted by the transmitting probe (21) are transmitted along the extending direction of the capillary tube, and the collecting probe (22) is used for collecting the ultrasonic waves transmitted by the transmitting probe (21);

the emission probe (21) and the collection probe (22) are respectively arranged at two ends of the capillary tube;

the vibration loading driving module is connected with the function generator and the echo collector (24), the function generator is used for sending out frequency sweeping signals and is connected with the electromagnetic oscillator (23), and the electromagnetic oscillator (23) conducts frequency sweeping oscillation according to the frequency sweeping signals sent out by the function generator; the electromagnetic oscillator (23) and the echo collector (24) are both arranged on the main clamp (12) and are arranged on the opposite side surfaces of the surface of the main clamp (12) contacted with the capillary, so that the oscillation emitted by the electromagnetic oscillator (23) can be transmitted to the capillary; the echo collector (24) collects the oscillation signal reflected from the capillary;

the bending loading driving module is connected with the angle encoder and the loading motor; the angle encoder is used for detecting the rotating angle of the wheel mould (14), and the loading motor is used for controlling the rotation of the wheel mould (14).

2. The double-layer capillary tube bending device for removing residual stress by vibration according to claim 1, wherein:

the emission probe (21) and the collection probe (22) have the same structure and comprise an end face circular plate (31), wherein the end face circular plate (31) is provided with an annular groove (32), and the annular groove is used for placing the end face of the capillary tube; 8 ultrasonic transducers (33) which are arranged in an annular mode at equal intervals are arranged on the outer side of the groove; therefore, 8 ultrasonic transducers of the transmitting probe (21) at one end emit 8 ultrasonic waves, 8 ultrasonic transducers (33) of the collecting probe (22) at the other end correspondingly collect 8 transmitted vibration signals, and the collecting probe (22) feeds back the strength of the collected 8 paths of vibration signals to the main controller.

3. A method of removing residual stress using the double layer capillary tube bending device of claim 2, comprising the steps of:

step 1, bending a capillary tube into a plurality of gradient change angles by using a bent tube clamp, wherein the gradient change angles are respectively 20 degrees, 40 degrees, 60 degrees, 80 degrees, 100 degrees, 120 degrees, 140 degrees, 160 degrees and 180 degrees; then taking down the bent capillary tube and carrying out annealing treatment to remove stress generated in the bending process;

step 2, re-mounting the annealed capillary tube on a bent tube clamp, and mounting a transmitting probe (21) and a collecting probe (22), wherein the transmitting probe (21) and the collecting probe (22) are respectively mounted at two ends of the capillary tube; the intensity of 8 paths of vibration signals of the annealed capillary corresponding collecting probe (22) is measured under the condition that the transmitting probe (21) uses 8 paths of ultrasonic drive with the same intensity, and the signals collected by the 8 paths are used as reference signals R _i ＝[r ₁ ,r ₂ ,…,r ₈ ]Wherein i is 1 to 9Corresponding to different bending angles, namely each bending angle corresponds to a group of reference signals;

step 3, mounting a new unbent capillary tube on a bent tube clamp, bending the new unbent capillary tube to the angles of 20 degrees, 40 degrees, 60 degrees, 80 degrees, 100 degrees, 120 degrees, 140 degrees, 160 degrees and 180 degrees respectively, controlling a vibration loading driving module to carry out frequency sweep oscillation under one angle, and simultaneously detecting whether the signal intensity I of an echo collector (24) is stable or not, wherein if the I generates step change, the situation that the installation of the capillary tube is unstable needs to be measured again; the emission probe (21) measures the intensity of 8 paths of vibration signals of the annealed capillary corresponding collection probe (22) under the drive of 8 paths of ultrasonic waves with the same intensity while sweeping the frequency, and the signals collected by the 8 paths are taken as detection signals Q _ij ＝[q _1j ,q _2j ,…,q _8j ]Wherein j is the frequency of the frequency sweep of the vibration loading driving module during detection, i is 1-9, and the frequency sweep corresponds to different bending angles, namely each oscillation frequency and one bending angle correspond to a group of detection signals, and the total is i multiplied by j groups of signals;

step 4, grouping the i multiplied by j groups of detection signals in the step 3 according to the same i, and dividing the detection signals into 9 groups, wherein the j groups of detection signals in each group respectively calculate the Mahalanobis distance between the detection signals and the corresponding reference signal of i; screening out a j with the minimum Mahalanobis distance from the group corresponding to each i; 9J are obtained, each J being ₁ ，J ₂ ，…，J ₉ (ii) a The 9J are the oscillation frequency driven by the optimal vibration loading driving module corresponding to 20-180 degrees;

step 5, taking an angle of 0-180 degrees as an abscissa and frequency as an ordinate, and combining (20 degrees, J) ₁ )、(40°，J ₂ )、(60°，J ₃ )、(80°，J ₄ )、(100°，J ₅ )、(120°，J ₆ )、(140°，J ₇ )、(160°，J ₈ )、(180°，J ₉ ) Filling the coordinate graph, and then connecting into a curve, namely an oscillation driving curve;

step 6, installing the capillary tube to be bent on a bending fixture, controlling a loading motor to perform bending loading, and then controlling a vibration loading driving module to drive and oscillate at a frequency corresponding to the angle on an oscillation driving curve according to the bending angle detected by an angle encoder; and after the bending is carried out to the required angle and the vibration is continued for a period of time at the corresponding frequency of the terminal angle on the vibration driving curve, the residual stress is removed.

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