CN103464536B - Vibration stress relief formation method and device under elastic deformation condition - Google Patents

Abstract

A vibration aging forming method and device under elastic deformation conditions. In the present invention, the metal sheet is bent and deformed through the action of the mold, and the deformation is within the elastic range. After the mold is removed, the metal sheet can be restored to its original state. In this way, a bending prestress is loaded on the sheet through the action of the mold, and the connection vibration The aging device generates a periodic exciting force through the exciter, and under its action, the sheet material reaches a resonance state, and uses resonance to eliminate and homogenize the internal bending prestress of the sheet material. Through the release process of this bending prestress, the The metal sheet produces a certain plastic deformation, and a curved part with a radius of curvature equivalent to the mold is obtained. The invention overcomes the problems of high mold manufacturing cost and difficult control of springback in the forming process of sheet metal parts, and reduces the frictional damage and vibration energy loss on the part surface during vibration aging, improves the surface quality of the formed workpiece, shortens the production cycle, and reduces the Cost of production.

Description

Vibration aging forming method and device under elastic deformation condition

technical field

The invention relates to the technical field of aging forming processing, in particular to a vibration aging forming method and device under elastic deformation conditions.

Background technique

In recent years, more and more vibration aging methods and corresponding equipment have been used in China. At the same time, it can deal with the stress of workpieces in an environmentally friendly, energy-saving and efficient manner. It strongly highlights its advantages and future development prospects, allowing more industrial manufacturers and enterprises Targeted use of vibration aging equipment to improve work efficiency and benefits. With the wide application of vibration aging, the technology has also made great progress. Vibration aging refers to the method that the exciter clamped on the workpiece generates a periodic exciting force, under its action, the component reaches a resonance state, the internal stress of the workpiece is relaxed, and the dimension of the workpiece is kept stable. Vibration stress relief is actually to superimpose the periodic dynamic stress with the internal stress of the workpiece, so that the component locally produces plastic deformation and releases the stress.

Chinese patent CN102551096A (a vibration aging method and vibration aging device for sheet metal parts) fixes the processed sheet metal parts together with the mold on the vibration aging table, fixes the exciter and the vibration aging table rigidly, and uses the control system Start the vibrator to vibrate the vibration aging table and the molded tires and sheet metal parts fixedly connected with it at the same time, so as to eliminate and homogenize the internal stress of the rice metal parts. However, this method has the following disadvantages. First, the sheet metal parts are directly used The bandage is bound on the mold tire, because the natural frequency of the sheet metal part and the mold tire is different, it will cause different vibration responses, cause friction on the contact surface, and affect the surface quality of the workpiece. In addition, the vibration energy of the exciter is transmitted to the Instead of the rigidly fixed mold tire, it is finally transmitted to the sheet metal parts that are firmly connected with the mold tire. This large-scale transmission will cause a large loss of vibration energy, which is not conducive to energy saving and environmental protection. Vibration aging is carried out in the elastic state of the material. However, the current research is mainly focused on the residual stress treatment of the formed workpiece, and the use of resonance to eliminate and homogenize the internal residual stress of the metal component can enhance the component's resistance to deformation and stabilize the size. precision.

British scholars Wardell and Walker researched on the basis of the technology that vibration can effectively prevent the formation of welding cracks and workpiece distortion, improve the fatigue life of components, and enhance the mechanical efficiency of welds. Before welding, the parts to be welded should be vibrated, and Welding while vibrating until the welding is finished, it can also save the post-welding stress relief treatment, shorten the production cycle, and reduce the production cost. This study shows that the vibration aging method is not only applied to the residual stress of the parts after plastic deformation. The treatment of stress can also be applied to the treatment of prestress before plastic deformation.

Contents of the invention

In order to overcome the deficiencies in the prior art of high mold manufacturing costs and difficult control of springback in the forming process of sheet metal parts, the present invention proposes a vibration aging forming method and device under elastic deformation conditions.

The specific steps of the vibration aging forming method under the elastic deformation condition of the present invention are:

In the first step, the sheet metal of the workpiece to be formed is installed.

The second step is to determine the resonant frequency of the workpiece. The exciter performs frequency sweeping, the sweeping frequency is 0-400Hz, the sweeping power is 400W, and the sweeping time is 6min. Record the amplitude frequency (A-f) curve of the workpiece to obtain the frequency sweep curve. If the obtained frequency sweep curve has an amplitude peak, forming a first-order formant, the frequency corresponding to the first-order formant is used as the resonance frequency of the workpiece. If the obtained frequency sweep curve has multiple amplitude peaks, the peak with the lowest frequency among the multiple amplitude peaks is used as the first-order formant, and the frequency corresponding to the first-order formant is used as the resonance frequency of the workpiece, and the frequency corresponding to the subsequent amplitude peaks as the higher resonant frequency.

The third step is vibration forming. In vibration forming, adjust the working frequency of the exciter to be consistent with the resonance frequency of the workpiece, and set the vibration aging time to 30min. Adjust the eccentricity of the exciter so that the peak value of the dynamic stress at the part where the stress is most concentrated in the bending forming of the workpiece is between 1/3 and 2/3 of the prestress value of the workpiece at this part for vibration aging. The output power of the exciter is 80% of the rated power of the exciter.

In the fourth step, after the vibration aging is over, the bending radius of the workpiece is measured. If the bending radius of the workpiece meets the design requirements, the bending of the workpiece is completed. If it exceeds the error range, re-clamp the workpiece and repeat step 3 for vibration compensation until the curvature radius of the workpiece meets the design requirements.

In the supplementary vibration, if the obtained frequency sweep curve has an amplitude peak, then take the frequency value near the resonance frequency of the workpiece obtained in step 2 as the working frequency of the vibrator for supplementary vibration; if the obtained frequency sweep curve has multiple amplitudes Peak, the high-order resonance frequency of the workpiece obtained in step 2 is used as the working frequency of the exciter for supplementary vibration.

The vibration aging forming device under the condition of elastic deformation according to the present invention comprises an upper mold, a lower mold, an exciter, a fixture, a base of the exciter, a sensor and a controller. The vibrator is located at one end of the workpiece, and is installed on the upper surface of the workpiece through the base of the vibrator. The upper surface of the exciter base cooperates with the bottom plate of the exciter; the vibrator, the base of the exciter and the lower mold are fastened by a clamp. The upper surface of the lower die is the arc surface required for forming the workpiece. There are multiple upper molds, all of which are strip-shaped. The lower surface of the upper mold is the concave surface required for forming the workpiece. When in use, the workpiece is placed on the upper surface of the lower mold; the upper mold is evenly distributed from the inside of the exciter at one end of the workpiece to the other end of the workpiece, and the distance between the side surfaces of two adjacent upper molds is 150~ 250mm. The sensor is placed on the upper surface of the other end of the workpiece; and communicates with the controller through a data line. Both the exciter and the sensor communicate with the controller.

When the workpiece is placed, a second rubber pad is placed between the workpiece and the upper surface of the lower mold, and a first rubber pad is also placed between the workpiece and the upper mold.

On the end surface of one end of the lower mold where the vibration exciter is installed, there is a rectangular groove for clamping the fixture.

The present invention realizes vibration aging forming under the condition of elastic deformation by designing a simple forming device. The specific forming method is: through the action of the mold, the flat metal material is bent and deformed, and the deformation is within the elastic range, and the mold is removed. Afterwards, the metal sheet can be restored to its original state. In this way, a bending prestress is applied to the sheet through the action of the mold, and the vibration aging device is connected to generate a periodic exciting force through the exciter. Under its action, the sheet reaches a resonance state , using resonance to eliminate and homogenize the internal bending prestress of the sheet metal, through the release process of this bending prestress, the metal sheet will produce a certain plastic deformation, and a curved part equivalent to the radius of curvature of the mold will be obtained.

The test device in the present invention is mainly composed of a controller, a vibrator, a sensor, a rubber pad, a fixture, a cable, a power cord, and a mould. When the device is assembled, the rubber pad, metal sheet, and upper mold are first installed On the lower mold, the vibrator is installed on the die with a clamp, and then the vibrator, the vibrator and the power supply are connected through the cable and the power line.

The present invention learns from the conventional vibration aging forming principle of eliminating residual stress under the condition of plastic deformation, and makes full use of vibration aging equipment. The operation is simple and the forming time is shortened from 20h for thermal aging to less than 40min. At the same time, rubber pads are used to separate the upper and lower molds from the sheet material to be formed, which can prevent friction damage on the surface of the sheet material, and the surface quality of the formed workpiece is good, avoiding the vibration energy of the exciter from being transmitted to the upper and lower molds, resulting in loss of vibration energy. A large amount of loss is beneficial to energy saving and environmental protection. In addition, the pre-bending deformation of the sheet is generated through the action of the mold, and then the vibration is eliminated and the internal bending prestress of the sheet is homogenized, which eliminates the cumbersome control process of defects such as springback and the residual after conventional forming. The treatment of stress shortens the production cycle and reduces the production cost.

The invention overcomes the disadvantages of high mold manufacturing cost and difficult springback control during the forming process of sheet metal parts, reduces surface friction damage and vibration energy loss of parts during vibration aging, and improves the surface quality of formed workpieces.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings.

Fig. 1 is a structural schematic diagram of the device of the present invention.

Figure 2 is a top view of the device of the present invention.

Fig. 3 is the cross-sectional view of the upper and lower molds, rubber pads and sheet metal connection structure in the device of the present invention.

Fig. 4 is a side view after removing the upper mold and the first rubber pad in the device of the present invention.

Fig. 5 is a schematic diagram of the structure of the lower mold in the device of the present invention.

Fig. 6 is a schematic diagram of the structure of the upper mold in the device of the present invention. in:

1. The first rubber pad, 2. Upper mold, 3. Work piece, 4. Lower mold, 5. Vibrator, 6. Fixture, 7. Vibrator base, 8. Sensor, 9. Controller, 10. The first Two rubber pads.

Detailed ways

Embodiment one

This embodiment is a method of vibration aging forming under elastic deformation conditions, and the specific steps are:

In the first step, the sheet metal of the workpiece to be formed is installed. Install the sheet material and the rubber pad of the workpiece to be formed between the upper mold and the lower mold, and make the upper surface of the first rubber pad fit the lower surface of the upper mold, and the lower surface of the second rubber pad and the lower mold. The upper surface is attached, and at the same time, the upper surface of the sheet material of the workpiece to be formed is attached to the lower surface of the first rubber pad, and the lower surface of the sheet material of the workpiece to be formed is attached to the upper surface of the second rubber pad. Secure the exciter to the sheet with conventional "C" clips. Connect the exciter and sensor and the power supply through the cable and power cord. Among them, the exciter chooses ZS1000K1 type, the rated excitation force of the exciter is 10KN, the rated power is 0.6KW, and the rated speed is 10000r/min.

The second step is to determine the resonant frequency of the workpiece. Firstly, the exciter performs frequency sweeping, the sweeping frequency is 0-400Hz, the sweeping power is 400W, and the sweeping time is 6min. During the frequency sweep, the exciter frequency gradually increases linearly. As the sweep frequency increases gradually, the amplitude of the workpiece changes. Record the amplitude frequency (A-f) curve of the workpiece to obtain the frequency sweep curve. If the obtained frequency sweep curve has an amplitude peak, forming a first-order formant, the frequency corresponding to the first-order formant is used as the resonance frequency of the workpiece. If the obtained frequency sweep curve has multiple amplitude peaks, the peak with the lowest frequency among the multiple amplitude peaks is used as the first-order formant, and the frequency corresponding to the first-order formant is used as the resonance frequency of the workpiece, and the frequency corresponding to the subsequent amplitude peaks as the higher resonant frequency.

The third step is vibration forming. In vibration forming, adjust the working frequency of the exciter to be consistent with the resonance frequency of the workpiece, and set the vibration aging time to 30min. Adjust the eccentricity of the exciter so that the peak value of the dynamic stress at the part where the stress is most concentrated in the bending forming of the workpiece is between 1/3 and 2/3 of the prestress value of the workpiece at this part for vibration aging. The output power of the exciter is 80% of the rated power of the exciter. In this embodiment, the output power of the exciter is 400W.

The fourth step is to measure the forming effect. After the vibration aging is over, turn off the power, disassemble the mold, remove the workpiece, measure the bending radius, and compare it with the expected value. If the bending radius of the workpiece meets the design requirements, the bending of the workpiece is completed. If it exceeds the error range, re-clamp the workpiece and repeat step 3 for vibration compensation until the curvature radius of the workpiece meets the design requirements. In supplementary vibration, if the obtained frequency sweep curve has an amplitude peak, then use the frequency value near the resonance frequency of the workpiece obtained in step 2 as the working frequency of the vibrator for supplementary vibration. If the obtained frequency sweep curve has multiple amplitude peaks, The high-order resonance frequency of the workpiece obtained in step 2 is used as the working frequency of the exciter for supplementary vibration until the bending radius of the workpiece meets the design requirements.

Embodiment two

This embodiment is a single-curvature workpiece forming device used to implement the vibration aging forming method under elastic deformation conditions described in Embodiment 1. The length of the formed workpiece is 1000mm, the width is 400mm, and the bending radius is 1500mm. The formed workpiece is an aluminum alloy plate.

The forming device of the single-curvature aluminum alloy workpiece comprises the first rubber pad 1 of the forming device, an upper mold 2, a lower mold 4, an exciter 5, a clamp 6, an exciter base 7, a sensor 8, a controller 9 and The second rubber pad 10.

The vibrator 5 is located at one end of the workpiece, and is installed on the upper surface of the workpiece 3 through the vibrator base 7 . The upper surface of the exciter base 7 cooperates with the bottom plate of the exciter, and the vibrator 5, the exciter base 7 and the lower mold 4 are fastened by the clamp 6. The lower surface of the vibrator base 7 is an arc surface adapted to the upper surface of the lower mold 4 . The control line of the vibrator 5 communicates with the controller 9 .

The upper surface of the lower mold 4 is the arc surface required for forming the workpiece. On the end surface of the end of the lower mold 4 where the vibrator 5 is installed, there is a rectangular groove for clamping the fixture 6 . There are three upper molds 2, all of which are bar-shaped. The lower surface of the upper mold 2 is the concave surface required for forming the workpiece. When in use, the workpiece is placed on the upper surface of the lower mold 4; the upper mold 2 is evenly distributed and tightened from the inside of the exciter 5 at one end of the workpiece to the other end of the workpiece. The distance between the side surfaces of two adjacent upper molds is 150-250 mm, and in this embodiment, the distance between the side surfaces of two adjacent upper molds is 180 mm.

The sensor 8 is placed on the upper surface of the other end of the workpiece, and communicates with the controller 9 through a data line.

When the workpiece 3 is placed, a second rubber pad 10 is placed between the workpiece 3 and the upper surface of the lower mold 4 , and a first rubber pad 1 is also placed between the workpiece 3 and the upper mold 2 .

The clamp 6 fastens the exciter 5 to the upper surface of the aluminum alloy sheet 3. The lower end of the clamp 6 is located in the rectangular groove on the end face of the lower mold 4, and the upper end is located above the upper surface of the bottom of the exciter 5. The upper end of the clamp 6 is bolted The bottom end surface is attached to the bottom upper surface of the vibrator 5 . The lower surface of the second rubber pad 10 is attached to the upper surface of the lower mold 4, while the lower surface of the aluminum alloy sheet material 3 is attached to the upper surface of the second rubber pad 10, and the upper surface of the aluminum alloy sheet material 3 is attached to the first The lower surface of the rubber pad is attached, and the upper surface of the first rubber pad 1 is attached to the lower surface of the upper mold 2 . The sensor 8 is installed on the upper surface of the aluminum alloy plate 3 at the end away from the vibrator 5 . There are threaded holes at the planes on both sides of the convex lower mold 4 to connect with the upper mold 2 .

The lower mold 4 is the carrier of this embodiment. The lower mold 4 is convex, and its size is determined according to the external dimensions of the workpiece to be formed, the assembly position of each component and the rigidity of the device. The material is 45 steel, and other The parts and the upper mold cooperate to make the sheet elastically bend and deform. A rectangular slot of 300 mm x 40 mm x 60 mm is provided at the place where the jig 6 is installed on the lower mold 4 to ensure the smooth installation and disassembly of the jig 6 . There are mounting holes for the upper mold 2 at the planes on both sides of the lower mold 4 .

The vibration exciter 5 is selected as ZS1000K1 type, and its parameters are as follows, the rated exciting force is 10KN, the rated power is 0.6KW, the rated speed is 10000r/min, the rated input current is 1.5A, the static force constant is 0.5kg/A, and the dynamic force is 0.5kg/A. The DC resistance of the coil is about 6Ω, the maximum displacement is 2mm, the mass of the movable part of the coil is 40g±10%, the overall size is Φ75×150mm, and the weight is about 3.5kg.

The upper mold 2 is concave, and the bottom has an arc-shaped inner groove. The curvature of the concave arc surface is consistent with the curvature of the convex arc surface of the aluminum alloy workpiece. The size of the upper mold 2 is determined by the outer dimension of the lower mold and the stiffness The requirements are determined, and the material is 45 steel, which cooperates with the lower mold to make the sheet material elastically bend and deform, and there are round holes at both ends for installing bolts to cooperate with the lower mold 4.

The base 7 of the vibrator is concave, and its size is determined by the external dimensions of the required forming workpiece and the vibrator and the rigidity of the forming device. The material is 45 steel, which plays the role of placing the vibrator. The curvature of the concave arc surface of the vibrator base 7 is consistent with the curvature of the convex arc surface of the aluminum alloy workpiece to ensure full contact between the two. During use, it is connected to the bottom of the vibrator 5 by welding to ensure the effect.

Both the first rubber pad 1 and the second rubber pad 10 are in the shape of a rectangular block. Since the vibrator 5 is installed on the upper surface of the aluminum alloy sheet 3, the concave arc surface of the vibrator base 7 is in line with the aluminum The outer convex arc surface of the alloy workpiece is fitted, and installation space needs to be reserved. The size of the first rubber pad 1 is smaller than the size of the second rubber pad 10, which can prevent the contact surface of the aluminum alloy workpiece from directly contacting the upper and lower molds. Friction affects the surface quality of the workpiece. In addition, it prevents the vibration energy of the exciter from being transmitted to the upper and lower molds, resulting in a large loss of vibration energy, which is conducive to energy saving and environmental protection.

The clamp 6 is in a "C" shape, and the vibrator 5 is fastened to the upper surface of the aluminum alloy sheet 3. The lower end of the clamp 6 is located in the rectangular groove on the end face of the lower mold 4, and the upper end is located at the bottom of the vibrator 5. Above the upper surface, the bottom end surface of the bolt at the upper end of the fixture 6 is attached to the bottom upper surface of the vibrator 5 .

Claims (5)

1. a vibration aging forming method under elastic deformation condition, is characterized in that, concrete steps are: The first step is to install the sheet of the workpiece to be formed; The second step is to determine the resonant frequency of the workpiece; the exciter performs frequency sweeping, the sweeping frequency is 0-400Hz, the sweeping power is 400W, and the sweeping time is 6min; the amplitude frequency (A-f) curve of the workpiece is recorded to obtain the sweeping frequency curve; if the obtained frequency sweep curve has an amplitude peak and forms a first-order formant, then the frequency corresponding to the first-order formant is used as the resonance frequency of the workpiece; if the obtained frequency sweep curve has multiple The peak with the lowest frequency among the two amplitude peaks is used as the first-order formant, and the frequency corresponding to the first-order formant is used as the resonant frequency of the workpiece, and the frequency corresponding to the subsequent amplitude peak is used as the high-order resonant frequency; The third step is vibration forming; during vibration forming, adjust the working frequency of the vibrator to be consistent with the resonance frequency of the workpiece, and set the vibration aging time to 30 minutes; adjust the eccentricity of the vibrator to make the stress of the workpiece most concentrated during bending forming The peak value of the dynamic stress of the part is between 1/3 and 2/3 of the prestress value of the workpiece at this part for vibration aging; the output power of the exciter is 80% of the rated power of the exciter; The fourth step, after the vibration aging is over, measure the bending radius of the workpiece. If the bending radius of the workpiece meets the design requirements, the bending of the workpiece is completed; if it exceeds the error range, re-clamp the workpiece, and repeat step 3 for vibration compensation until the workpiece The radius of curvature meets the design requirements. 2. The vibration aging forming method under the elastic deformation condition as claimed in claim 1, is characterized in that, in the supplementary vibration, if the frequency sweep curve obtained has an amplitude peak, then get the frequency value near the resonance frequency of the workpiece obtained in step 2 Supplement vibration as the working frequency of the exciter; if the obtained frequency sweep curve has multiple amplitude peaks, use the high-order resonance frequency of the workpiece obtained in step 2 that is closest to the original resonance frequency as the exciter The working frequency is supplemented by vibration. 3. A device for realizing the vibration aging forming method under the condition of elastic deformation according to claim 1, characterized in that it comprises an upper mold, a lower mold, a vibrator, a clamp, a vibrator base, a sensor and a controller ;The vibrator is located at one end of the workpiece, and is installed on the upper surface of the workpiece through the base of the vibrator; the upper surface of the base of the vibrator cooperates with the bottom plate of the vibrator; the vibrator, the base of the vibrator and the lower mold Fastening; the upper surface of the lower mold is the arc surface required for forming the workpiece; there are multiple upper molds, all of which are strip-shaped; the lower surface of the upper mold is the concave surface required for forming the workpiece; when in use, the workpiece is placed on the bottom The upper surface of the mold; the upper mold is evenly distributed from the inside of the exciter at one end of the workpiece to the other end of the workpiece, and the distance between two adjacent upper mold side surfaces is 150-250mm; the sensor is placed on the other side of the workpiece The upper surface of one end; and communicate with the controller through the data line; both the exciter and the sensor communicate with the controller. 4. The device for realizing the vibration aging forming method under the condition of elastic deformation as claimed in claim 3, characterized in that, when the workpiece is placed, a second rubber pad is placed between the workpiece and the upper surface of the lower mold, and A first rubber pad is also arranged between the mold and the upper mold. 5 . The device for realizing the vibration aging forming method under elastic deformation conditions as claimed in claim 3 , characterized in that there is a rectangular groove for clamping the clamp on the end face of the lower mold where the vibrator is installed. 6 .