De-core machine vibration reduction method based on distributed vibration absorbers

Abstract

The invention discloses a core removing machine vibration reduction method based on a distributed vibration absorber, the distributed vibration absorber is composed of a plurality of vibration absorption units arranged on an external fixing structure of a core removing machine, and core removing machine modal information corresponding to frequency to be subjected to vibration reduction and vibration amplitude information in all directions are obtained through modal analysis and harmonic response analysis; the vibration absorption unit and the vibration absorber have similar inherent frequency, and within the frequency range to be subjected to vibration reduction, the vibration energy of the core removing machine is absorbed through vibration of the vibration absorption unit. Vibration reduction of non-working vibration of the core removing machine is achieved, the working stability and reliability of the core removing machine are remarkably improved, and the safety of the working environment of the core removing machine can be effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of mechanical structure fatigue life modeling technology, specifically a vibration reduction method for a core removal machine based on a distributed vibration absorber. Background Technology

[0002] A core remover is a device used to remove sand cores from the internal cavities of castings. Its main function is to use a pneumatic or electric high-frequency vibratory hammer to impact the casting, loosening the sand cores inside. Simultaneously, it utilizes a vibratory motor and a rotating device to continuously rotate the casting during vibration, thus helping to remove the loosened sand cores. With this efficient vibration and impact, the core remover can quickly and thoroughly remove sand cores from castings, effectively improving the cleanliness and quality of the castings. However, experimental tests have revealed that the core remover exhibits significant vibration in non-operating vibration directions. The noise generated by this vibration has a significant impact on the production environment and also significantly reduces the service life of the core remover. Therefore, developing a vibration reduction solution that can operate stably for extended periods in extreme environments such as high temperatures has become a key challenge in suppressing unnecessary vibrations in the core remover. Summary of the Invention

[0003] The purpose of this invention is to provide a vibration reduction method for a core remover based on a distributed vibration absorber, addressing the vibration reduction requirements within the frequency range to be reduced for the core remover. By matching the natural frequency and corresponding mode shape of the vibration-absorbing unit in the distributed dynamic vibration absorber with the vibration reduction frequency and vibration amplitude information of the core remover, unnecessary amplitudes at the vibration reduction frequency of the core remover are suppressed, thereby reducing the resonance amplitude of the core remover during operation and improving the reliability of the structure.

[0004] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: a vibration reduction method for a core removal machine based on a distributed vibration absorber, wherein the distributed vibration absorber includes multiple vibration absorption units, characterized in that: Vibration-absorbing units are installed at different positions on the external fixed structure of the core remover; Based on the vibration frequency to be reduced and the corresponding vibration amplitude information of the core removal machine, the same structural parameters are set for all vibration absorption units; All vibration absorption units are matched with the vibration amplitude information of the core remover, so that the first natural frequency and corresponding mode shape of the vibration absorption unit oscillator are the same as the vibration frequency and vibration amplitude information of the core remover to be reduced, thereby suppressing the vibration of the core remover body.

[0005] In a preferred embodiment of the present invention, the parameter matching of all vibration absorption units with the vibration amplitude information of the core remover is performed according to the following steps: Step 1: Establish a finite element model of the core remover, import it into the finite element simulation analysis software, construct a finite element vibration simulation model, determine the frequency range to be reduced based on the actual working conditions, and then perform vibration modal analysis and harmonious response analysis on the core remover based on the modal superposition method to obtain the mode shape of the core remover and the vibration amplitude information at the aforementioned frequency to be reduced. Step 2: Based on the vibration frequency to be reduced and its corresponding vibration amplitude information obtained in Step 1, determine the structural parameters of the vibration absorption unit oscillator to ensure that the natural frequency of the vibration absorption unit is consistent with the vibration frequency to be reduced. Step 3: Construct the finite element model of the target model vibration absorption unit, and perform vibration mode analysis on the vibration absorption unit based on the modal superposition method to obtain the natural frequency and mode shape of the vibration absorption unit.

[0006] As a preferred embodiment of the present invention, step two specifically includes: Step 2.1: Referring to the frequency range to be reduced in Step 1, initially plan the structural natural frequency of the vibration absorption unit, initially ensuring that the ratio of the natural frequency of the vibration absorption unit to that of the core remover is [value missing]. The mass ratio of the two is Based on these settings, the initial structural parameters of the vibration-absorbing unit were designed, and a finite element model of the vibration-absorbing unit was constructed to obtain the initial mass of the vibration-absorbing unit. and initial stiffness ; Step 2.2: Scale the reference structural parameters of the vibration-absorbing unit to generate an intermediate model, while maintaining... In the case of a value, the mass ratio of the initial model is changed from... The design was changed to The relevant parameters of the vibration-absorbing element in the transition model are obtained: ,

[0007] in: and These represent the mass and stiffness of the transition model, respectively. It is the scaling factor for transitioning from the initial model to the transition model; Step 2.3: Maintain the mass ratio of the model in Step 2.2 The stiffness of the elastic beam portion of the vibration-absorbing element in the transition model remains unchanged; only the stiffness of the elastic beam portion is changed. The frequency ratio of the transition model Change to The mass ratio is obtained as The frequency ratio is Parameters related to the target model vibration-absorbing element:

[0008] in: It is the elastic beam part of the vibration-absorbing unit stiffness of the target model; It is the scaling factor; It is the elastic beam part of the initial model's vibration-absorbing unit stiffness.

[0009] In a preferred embodiment of the present invention, the total mass of all oscillators in the vibration absorption unit is 1%-5% of the mass of the core remover.

[0010] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in the following aspects: 1. In this invention, the distributed vibration absorber is directly installed on the core removal machine, which has a simple structure, does not affect the working performance and design and manufacturing process of the core removal machine, and is easy to implement; 2. This invention achieves the suppression of vibration of the core remover body by matching the vibration absorption unit in the distributed dynamic vibration absorber with the vibration amplitude information of the core remover, effectively reducing the vibration amplitude of the core remover at typical vibration frequencies and improving the reliability of the structure. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the vibration reduction method for the core removal machine in this invention.

[0012] Figure 2 This is a schematic diagram of the specific structure of the core removal machine and the distributed vibration absorber in this invention.

[0013] Figure 3 This is a schematic diagram of the finite element geometric model of the core removal machine embodiment of the present invention.

[0014] Figure 4 This is a schematic diagram of the cantilever beam portion of the vibration absorption unit in this invention.

[0015] Figure 5 This is a schematic diagram of the mode shape of the vibration absorption unit in the core removal machine embodiment of the present invention.

[0016] Figure 6 This is a schematic diagram of the finite element geometric model of the core removal machine with distributed vibration absorbers in this invention.

[0017] The diagram shows: 1 represents the distributed vibration absorber, and 2 represents the overall structure of the core removal machine. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and specific analytical embodiments: This embodiment discloses a vibration reduction method for a core removal machine based on a distributed vibration absorber. The core removal machine is a vibration system consisting of a vibrating part, an external fixed structure, and a base. The vibrating part is connected to and fixed by the external fixed structure, which is connected to the base via vibration isolators. In this embodiment, the vibrating part of the core removal machine is connected to and fixed to the external fixed structure via two discs on both sides. Simultaneously, the external fixed part is connected to the base via vibration isolators. A schematic diagram of the specific structure of the core removal machine and the distributed vibration absorber is shown below. Figure 2 As shown, the distributed vibration absorber 1 consists of multiple vibration-absorbing units. Each vibration-absorbing unit comprises a mass block and a cantilever beam, and the units are connected to an external fixed structure by bolts or welding. The cantilever beam is a slender structure used to connect the mass blocks.

[0019] Distributed vibration absorbers consist of vibration-absorbing units set at different locations on an external fixed structure. In this embodiment, vibration absorbers are set at the four corners of the bottom of the external fixed structure, with one vibration-absorbing unit at each corner. Based on the vibration frequency and corresponding vibration amplitude information of the core remover, all vibration-absorbing units are set to have the same structural parameters. In this embodiment, since the normal operating frequency of the core remover is 24.5Hz, 24.5Hz is set as the vibration frequency to be reduced. All vibration-absorbing units are parameter-matched with the vibration amplitude information of the core remover, so that the first natural frequency and corresponding mode shape of the oscillator of the vibration-absorbing unit are the same as the vibration frequency and vibration amplitude information of the core remover, thus achieving suppression of the vibration of the core remover body.

[0020] The parameter matching of all vibration absorption units with the vibration amplitude information of the core remover is performed according to the following steps: Step 1: Establish the finite element geometric model of the core removal machine, such as... Figure 3 As shown, the finite element simulation analysis software is imported to construct a finite element vibration simulation model. The frequency range to be reduced is determined according to the actual working conditions. Then, the vibration mode analysis and harmonious response analysis of the core remover are performed based on the modal superposition method to obtain the mode shape of the core remover and the vibration amplitude information at the aforementioned frequency to be reduced. In this embodiment, the core remover usually works under sinusoidal excitation with a frequency of 24.5Hz and an amplitude of 180kN. At this time, the maximum amplitude of the external fixed structure of the core remover in the Z-axis direction is 6.10E-5m. Step 2: Based on the vibration frequency to be reduced and its corresponding vibration amplitude information obtained in Step 1, determine the structural parameters of the vibration absorption unit oscillator to ensure that the natural frequency of the vibration absorption unit is consistent with the vibration frequency to be reduced. Specifically, this includes: Step 2.1: Referring to the frequency range to be reduced in Step 1, initially plan the structural natural frequency of the vibration absorption unit, initially ensuring that the ratio of the natural frequency of the vibration absorption unit to that of the core remover is [value missing]. The mass ratio of the two is Based on these settings, the initial structural parameters of the vibration-absorbing unit were designed, and a finite element model of the vibration-absorbing unit was constructed to obtain the initial mass of the vibration-absorbing unit. and initial stiffness .

[0021] Step 2.2: Scale the reference structural parameters of the vibration-absorbing unit to generate an intermediate model, while maintaining... In the case of a value, the mass ratio of the initial model is changed from... The design was changed to The relevant parameters of the vibration-absorbing element in the transition model are obtained: , (1) in: and These represent the mass and stiffness of the transition model, respectively. It is the scaling factor that changes the model from the initial model to the transition model.

[0022] Keeping the vibration absorber's geometry (length, width) constant, only changing its thickness. Taking the cantilever rectangular beam in this embodiment as an example, as... Figure 4 As shown, its mass and stiffness are respectively , ,in , , These are the length, width, and height of the cantilever beam, respectively. and These represent the beam's density and Young's modulus, respectively. At this point, the mass (linearly related to the height) and stiffness (linearly related to the height cube) change synchronously.

[0023] Step 2.3: Maintain the mass ratio of the model in Step 2 The stiffness remains unchanged, only the stiffness of the elastic beam portion of the vibration-absorbing unit in the transition model is changed. The frequency ratio of the transition model Change to The mass ratio is obtained as The frequency ratio is Parameters related to the target model vibration-absorbing element: (2) in: It is the elastic beam part of the vibration-absorbing unit stiffness of the target model; It is the scaling factor; It is the elastic beam part of the initial model's vibration-absorbing unit stiffness.

[0024] In this embodiment, the frequency ratio of the target vibration absorption unit is... quality ratio .

[0025] Step 3: Construct the finite element model of the target model vibration-absorbing unit, and perform vibration modal analysis on the vibration-absorbing unit based on the modal superposition method to obtain the natural frequencies and mode shapes of the vibration-absorbing unit, such as... Figure 5 As shown in the figure, it can be seen that the mode shape of the vibration absorption unit at a frequency of 25Hz meets the design requirements.

[0026] In this embodiment, the total mass of all oscillators in the vibration absorption unit is selected to be 3% excluding the external fixed structure of the core machine.

[0027] Finally, based on the structural parameters of the oscillator of the vibration-absorbing unit, a finite element model of the core-removing machine with distributed vibration absorbers is constructed, such as... Figure 6 As shown, a vibration harmonic response analysis was performed on the core remover with distributed vibration absorbers to obtain the displacement amplitude in the vibration direction to be reduced, and compared with the displacement amplitude in the vibration direction to be reduced of the core remover described in step 1. In this embodiment, by performing vibration harmonic response analysis on the finite element model of the core remover with distributed vibration absorbers, the amplitude of the external fixed structure of the core remover in the Z-axis direction is 3.61E-5m, and the vibration reduction effect reaches 40%, which is significant.

[0028] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be modified within the scope of the concept described herein by means of the above teachings or the technology or knowledge in related fields.

Claims

1. A vibration reduction method for a core removal machine based on a distributed vibration absorber, wherein the distributed vibration absorber comprises multiple vibration absorbing units, characterized in that: Vibration-absorbing units are installed at different positions on the external fixed structure of the core remover; Based on the vibration frequency to be reduced and the corresponding vibration amplitude information of the core removal machine, the same structural parameters are set for all vibration absorption units; All vibration absorption units are matched with the vibration amplitude information of the core remover, so that the first natural frequency and corresponding mode shape of the vibration absorption unit oscillator are the same as the vibration frequency and vibration amplitude information of the core remover to be reduced, thereby suppressing the vibration of the core remover body.

2. The vibration reduction method for a core removal machine based on a distributed vibration absorber according to claim 1, characterized in that, The parameter matching of all vibration absorption units with the vibration amplitude information of the core remover is performed according to the following steps: Step 1: Establish a finite element model of the core remover, import it into the finite element simulation analysis software, construct a finite element vibration simulation model, determine the frequency range to be reduced based on the actual working conditions, and then perform vibration modal analysis and harmonious response analysis on the core remover based on the modal superposition method to obtain the mode shape of the core remover and the vibration amplitude information at the aforementioned frequency to be reduced. Step 2: Based on the vibration frequency to be reduced and its corresponding vibration amplitude information obtained in Step 1, determine the structural parameters of the vibration absorption unit oscillator to ensure that the natural frequency of the vibration absorption unit is consistent with the vibration frequency to be reduced. Step 3: Construct the finite element model of the target model vibration absorption unit, and perform vibration mode analysis on the vibration absorption unit based on the modal superposition method to obtain the natural frequency and mode shape of the vibration absorption unit.

3. The vibration reduction method for a core removal machine based on a distributed vibration absorber according to claim 2, characterized in that: Step two specifically includes: Step 2.1: Referring to the frequency range to be reduced in Step 1, initially plan the structural natural frequency of the vibration absorption unit, initially ensuring that the ratio of the natural frequency of the vibration absorption unit to that of the core remover is [value missing]. The mass ratio of the two is Based on these settings, the initial structural parameters of the vibration-absorbing unit were designed, and a finite element model of the vibration-absorbing unit was constructed to obtain the initial mass of the vibration-absorbing unit. and initial stiffness ; Step 2.2: Scale the reference structural parameters of the vibration-absorbing unit to generate an intermediate model, while maintaining... In the case of a value, the mass ratio of the initial model is changed from... The design was changed to The relevant parameters of the vibration-absorbing element in the transition model are obtained: , ， in: and These represent the mass and stiffness of the transition model, respectively. It is the scaling factor for transitioning from the initial model to the transition model; Step 2.3: Maintain the mass ratio of the model in Step 2.2 The stiffness of the elastic beam portion of the vibration-absorbing element in the transition model remains unchanged; only the stiffness of the elastic beam portion is changed. The frequency ratio of the transition model Change to The mass ratio is obtained as The frequency ratio is Parameters related to the target model vibration-absorbing element: ， in: It is the elastic beam part of the vibration-absorbing unit stiffness of the target model; It is the scaling factor; It is the elastic beam part of the initial model's vibration-absorbing unit stiffness.

4. The vibration reduction method for a core removal machine based on a distributed vibration absorber according to claim 2, characterized in that: The total mass of all oscillators in the vibration absorption unit is 1%-5% of the mass of the core remover.

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