CN107135749B - It is a kind of control the low-frequency vibration of longitudinally axial flow threshing roller quasi- zero stiffness answer girder construction - Google Patents

Abstract

The invention provides a quasi-zero stiffness compound beam structure for controlling the low-frequency vibration of a longitudinal axial flow threshing drum, comprising a left column, a right column, a quasi-zero stiffness compound beam, a right connecting piece of the compound beam and a left connecting piece of the compound beam, and the quasi-zero stiffness The right side of the compound beam is connected with the right connecting piece of the compound beam, the left side of the compound beam is connected with the left connecting piece of the compound beam, the right connecting piece of the compound beam is connected with the right column, and the left connecting piece of the compound beam is connected with the left column. The load-bearing position is connected with the threshing drum shaft through the threshing drum bearing seat; the positive stiffness and negative stiffness of the positive stiffness beam when the dynamic load of the longitudinal axial flow threshing drum is in the equilibrium position, the total stiffness of the negative stiffness generated by the prestress of the buckling beam shaft end is approximately zero When the quasi-zero stiffness compound beam balance point is formed; at the equilibrium state of the quasi-zero stiffness compound beam, the positive and negative stiffness beam structure is fixed by the connecting screw, and the connection pad is filled in the balance position of the positive stiffness beam and the negative stiffness buckling beam; this The invention can effectively control the low frequency vibration generated during the threshing process of the longitudinal axial flow drum.

Description

A quasi-zero stiffness compound beam structure for controlling low frequency vibration of longitudinal axial flow threshing drum

technical field

The invention belongs to the field of bearing frame structures of a threshing and separating device of a combine harvester, in particular to a quasi-zero stiffness compound beam structure for controlling the low-frequency vibration of a longitudinal axial flow threshing drum.

Background technique

The longitudinal axial flow threshing drum of the combine harvester is constrained by the entanglement of rice stalks during the threshing process. During the threshing process of the longitudinal axial flow drum, the obvious vibration generated by the drum occurs with the beginning of threshing, changes with the fluctuation of the feeding amount, and disappears with the end of threshing , the vibration characteristics are transient, and it is difficult to reduce vibration. The vibration generated during the threshing process of the longitudinal axial flow drum often causes the structural resonance of the centrifugal fan, vibrating screen, return plate, shaking plate, tangential flow drum or frame on the bearing frame, which seriously affects the structural reliability and threshing performance of the threshing device. The article "Vibration test and analysis of crawler-type full-feed rice combine harvester" in the 30(8) issue of "Chinese Journal of Agricultural Engineering" in 2014 pointed out that the maximum excitation frequencies of the combine harvester threshing drum no-load and field harvesting were 12.70Hz and 23.44Hz, respectively. Hz; in 2014, the article "Dynamic balancing of the threshing drum in combine harvesters-The process, sources of imbalance and negative impact of mechanical vibrations" in "Applied Mechanics and Materials" No. 69(3) pointed out that the main frequency vibration of the combine harvester threshing drum is less than 30Hz . Foreign large combine harvesters have a dead weight of 10t to 15t, and the vibration during the threshing process is often controlled by adjusting the rotational inertia of the drum, but this method will increase the power consumption or the weight of the whole machine during the threshing process of the drum; hydraulic drive damping is used to control the drum The vibration method in the threshing process is currently difficult to match with the existing crawler combine harvester structure.

Since the natural frequency of the structure is proportional to the stiffness, the natural frequency of the quasi-zero stiffness structure with approximately zero stiffness is also approximately zero, and the quasi-zero stiffness structure is often used for vibration isolation control at medium and low frequencies. The patent CN201510418855.0 invented a quasi-zero stiffness vibration isolation system and its nonlinear feedback control method, which can solve the suppression resonance peak in the passive vibration isolation system and the feedback control system, and reduce the amplitude of the main resonance peak of the vibration isolation system; the patent CN201610182527.X invented a quasi-zero stiffness pressure rod, which can be installed on various vibration isolation platforms, so that it has the characteristics of high static and low dynamic stiffness in each degree of freedom, so as to realize low frequency vibration isolation; patent CN201610599158.4 invented a A three-dimensional isolation/vibration bearing with quasi-zero stiffness characteristics, the invented disc spring is just in a flattened state, and the vertical isolation/vibration system is in a state of quasi-zero stiffness, which can isolate vertical vibration or earthquakes; However, the existing quasi-zero stiffness vibration reduction structure cannot match the structure of the combine harvester threshing drum and the bearing frame. Since the rice feeding is time-varying during the harvesting of the combine harvester, the eccentric load and unbalanced vibration in the drum threshing process cannot be avoided due to the separation of the grains and the confinement of the flexible rice straw during the drum threshing process, but it is difficult to use the The vibration in the drum threshing process is controlled by methods such as heavy weight, reverse vibration and hydraulic controllable damping. Therefore, it is necessary to design the vibration control quasi-zero stiffness vibration damping compound beam structure of the longitudinal axial flow drum of the crawler combine harvester according to the characteristics of the rice harvesting period in my country.

SUMMARY OF THE INVENTION

In view of the obvious vibration phenomenon of the existing crawler-type combine harvester longitudinal axial flow drum during threshing, it occurs with the beginning of threshing, changes with the fluctuation of the feeding amount, and disappears with the end of threshing. The vibration characteristics are transient and it is difficult to reduce vibration. The present invention provides a quasi-zero stiffness compound beam structure for controlling the low-frequency vibration of a longitudinal axial flow threshing drum. The right connector is connected to the right column, the left connector of the compound beam is connected to the left column, and the middle of the quasi-zero-stiffness compound beam is connected to the threshing drum shaft through the threshing drum bearing seat; the positive stiffness cross beam is in a balanced position by the dynamic load of the longitudinal axial flow threshing drum The quasi-zero stiffness compound beam equilibrium point is formed when the total stiffness of the negative stiffness is approximately zero when the axial end of the buckling beam is extruded by the prestressed screw to generate prestress; The low-frequency vibration generated during the threshing process of the threshing drum is controlled by vibration isolation.

The present invention achieves the above technical purpose through the following technical means.

A quasi-zero-stiffness compound beam structure for controlling low-frequency vibration of a longitudinal axial-flow threshing drum is characterized in that it includes left and right columns fixed on a chassis frame, a quasi-zero-stiffness compound beam, a right connecting piece of the compound beam and a compound beam Left connector; the quasi-zero-stiffness compound beam includes a positive-stiffness beam, a negative-stiffness buckling beam, and a positive-negative stiffness beam connecting pad, the positive-stiffness beam is located on the upper side of the negative-stiffness buckling beam, and the middle of the two are fixedly connected, and the positive and negative stiffness The beam connecting pad is located in the gap between the positive stiffness cross beam and the middle of the negative stiffness buckling beam; the left and right ends of the quasi-zero stiffness compound beam are respectively connected to the left column and the right column through the compound beam right connecting piece and the compound beam left connecting piece. The right connecting piece of the compound beam is provided with a prestressed screw to apply prestress to the negative stiffness buckling beam; both ends of the threshing drum shaft of the threshing drum are mounted in the middle of the quasi-zero stiffness compound beam through a bearing seat.

Further, the positive stiffness of the positive stiffness beam when it is in the equilibrium position under the action of the dynamic load of the longitudinal axial flow threshing drum where E ₁ is the modulus of elasticity of the beam with positive stiffness, I ₁ is the moment of inertia of the beam with positive stiffness, π is a constant 3.14, and L is the length of the beam with positive stiffness; the axial end of the buckling beam with negative stiffness is extruded by a prestressed screw to generate prestress Negative stiffness at where E ₂ is the elastic modulus of the negative stiffness buckling beam, I ₂ is the moment of inertia of the negative stiffness buckling beam, π is the constant 3.14, l is the length of the negative stiffness buckling beam, and k is the stiffness of the negative stiffness buckling beam in the free state; positive stiffness The stiffness k ⁺ +K ^- ≈0 of the cross beam and the negative stiffness buckling beam at the equilibrium point produces a quasi-zero stiffness compound beam equilibrium point, and is fixed by the positive and negative stiffness beam connecting screws at the equilibrium state of the quasi-zero stiffness compound beam. The negative stiffness beam connecting screw is a U-shaped screw.

Further, the right end of the negative stiffness buckling beam is connected with a negative stiffness buckling beam stress transverse plate, the right end surface of the stress transverse plate is provided with a screw positioning sleeve, and the prestressed screw rod extends into the screw positioning sleeve and is positioned by it. The left end face of the negative stiffness buckling beam stress transverse plate is provided with a negative stiffness buckling beam right connecting ear, and the right end of the negative stiffness buckling beam is connected with the negative stiffness buckling beam right connecting ear through bolts.

Further, the right connecting piece of the compound beam comprises a right connecting U-shaped sleeve of the compound beam and a prestressed nut, and the right connecting U-shaped sleeve of the compound beam is fixed on the right column by 2 bolts; the right connecting U-shaped sleeve of the compound beam is The upper part is provided with a circular through hole for assembling the positive stiffness beam, the prestressed nut is fixed on the right end surface of the right connecting U-shaped sleeve of the compound beam, and the prestressed screw rod passes through the right column and the prestressed nut and the negative stiffness buckling beam The stress transverse plates are connected; the left connecting piece of the compound beam includes a left connecting U sleeve of the compound beam and a left connecting U-shaped sleeve lug, and the left connecting U sleeve of the compound beam is fixed on the left column by 2 bolts; the upper part of the left connecting piece of the compound beam is provided with There is a circular through hole for assembling the positive stiffness beam; the left end of the negative stiffness buckling beam is a circular ring, which is fixed on the left connecting U-shaped sleeve by bolts; the two ends of the positive stiffness beam are respectively installed on the left connector of the compound beam, Connect the right inside the circular through hole of the U-shaped sleeve.

Further, a positioning collar 504 is respectively fixed on the upper side of the middle part of the negative stiffness buckling beam and the lower side of the positive stiffness cross beam middle part; the negative stiffness buckling beam middle part and the positive stiffness transverse beam middle part are connected by the positioning collar.

Further, the quasi-positive stiffness beam and the negative stiffness buckling beam are both leaf springs with a width of 40mm to 60mm, a thickness of 2mm to 4mm, and a length of 500mm to 600mm; Two through holes with an inner diameter of 12mm to 16mm are opened within 25mm of the right edge of the negative stiffness buckling beam.

Beneficial effects of the present invention:

(1) The present invention designs a quasi-zero-stiffness compound beam structure for controlling the low-frequency vibration of the longitudinal-axial-flow threshing drum for the low-frequency vibration isolation caused by the entanglement of rice stalks in the process of longitudinal axial flow threshing. The buckling beam, the positioning ring, the positive and negative stiffness beam connecting screws, and the positive and negative stiffness beam connecting pads are composed. When the positive stiffness beam is in a balanced position by the dynamic load of the longitudinal axial flow threshing drum, the positive stiffness and negative stiffness buckling beam shaft ends are prestressed When the total stiffness that produces negative stiffness is approximately zero, a quasi-zero stiffness compound beam equilibrium point is formed; at the quasi-zero stiffness compound beam equilibrium point, it has the characteristics of high static and low dynamic stiffness; The low-frequency vibration generated in the threshing process of the threshing drum is controlled by vibration isolation, which solves the vibration transmission caused by the eccentric load and the unbalanced vibration that exist with the separation of the grains and the winding constraint of the flexible rice straw during the threshing process of the drum.

(2) The prestressed screw rod of the present invention passes through the prestressed nut and is in contact with the negative stiffness buckling beam stress transverse plate. The left end of the prestressed screw rod is limited by the screw positioning sleeve, and the prestressed screw rod and the prestressed nut are prestressed Prestress is applied to the stress transverse plate of the negative stiffness buckling beam. The prestressing structure of the shaft end of the negative stiffness buckling beam is simple. By adjusting the prestressing screw, the negative stiffness of the negative stiffness buckling beam can be easily controlled, and the negative stiffness buckling beam structure adjustment and operation. Simple; it is also possible to precisely adjust the negative stiffness buckling beam axial end prestress according to the yield and growth characteristics of field crops to construct a quasi-zero stiffness compound beam structure suitable for harvesting different crops.

(3) When the positive and negative total stiffness of the positive and negative stiffness beams of the present invention at the balance point is zero, the balance point of the quasi-zero stiffness compound beam is generated to control the vibration during the threshing process of the longitudinal axial flow drum, and the quasi-zero stiffness compound beam The structure and external dimensions are matched with the existing crawler-type combine harvesters, and can directly replace the longitudinal axial flow threshing drum bearing beams of the existing crawler-type combine harvesters, and the present invention can also be directly applied to the existing crawler-type rice combine harvesters On the machine, the research and development cost is reduced, and the versatility and universality of the present invention are greatly improved.

(4) The right side of the quasi-zero stiffness compound beam of the present invention is connected with the right connecting piece of the compound beam, the left side of the quasi-zero stiffness compound beam is connected with the left connecting piece of the compound beam, and the right connecting piece of the compound beam is U-shaped sleeved on the right column. The left connecting U sleeve of the compound beam is sleeved on the left column, and then the middle part of the quasi-zero stiffness compound beam is connected to the threshing drum shaft of the threshing drum through the threshing drum bearing seat. The beam, the prestressed buckling beam does not change the original structure and working parameters of the roller frame, which ensures the strength and stability of the bearing beam under the dynamic load excitation, and solves the difficulty in using the existing quasi-zero stiffness structure to bear the dynamic load of the longitudinal axial flow roller. Ensure the strength and stability of dynamic load bearing in the process of drum threshing.

Description of drawings

Fig. 1 The assembly diagram of the quasi-zero stiffness compound beam structure and the longitudinal axial flow threshing drum.

Figure 2 Schematic diagram of the quasi-zero stiffness compound beam structure and the assembly structure of the longitudinal axial flow threshing drum.

Figure 3 is a top view of the quasi-zero stiffness compound beam assembled with the column through the connector.

Figure 4 Schematic diagram of the assembly of the stress member on the right side of the negative stiffness buckling beam.

Fig. 5 Schematic diagram of the assembly of the stress-bearing members of the negative-stiffness yield beam stress plate.

Figure 6 is a top view of the left connecting piece of the compound beam.

Figure 7 is a right side view of the left connecting piece of the compound beam.

Figure 8 is a top view of the right connecting piece of the compound beam.

Figure 9 is a left side view of the right connector of the compound beam.

Figure 10 Right side view of the right connector of the compound beam.

Figure 11 Front view of a positive stiffness beam.

Figure 12 Front view of a negative stiffness buckling beam.

Figure 13. Top view of a negative stiffness buckling beam.

Figure 14 Front view of the positive and negative stiffness beam connecting screws.

Figure 15. Top view of the positioning ferrule.

Figure 16 Front view of the right connecting ear of a negative stiffness buckling beam.

Fig. 17 Front view of the stress transverse plate of negative stiffness yielding beam.

Figure 18 Front view of the screw positioning sleeve.

Figure 19 Front view of the left connecting U-shaped lug.

Figure 20 Front view of the prestressing screw.

Figure 21 Front view of the left column.

Figure 22 Front view of the right column.

Figure 23 Schematic diagram of the structure of the positive stiffness beam and the negative stiffness buckling beam in the free state.

Figure 24 Schematic diagram of the low-frequency vibration of the quasi-zero stiffness compound beam controlled longitudinal axial flow drum.

The reference numerals are explained as follows:

1- Chassis frame, 2- Left column, 3- Right column, 4- Concave plate screen, 5- Quasi-zero stiffness compound beam, 501- Positive stiffness beam, 501A- Positive stiffness beam left, 501B- Positive stiffness beam right Side, 502 - Negative stiffness buckling beam, 502A - Negative stiffness buckling beam left, 502B - Negative stiffness buckling beam right, 503 - Positive and negative stiffness beam connection pads, 504A - Positive stiffness beam collar, 504B - Negative stiffness buckling beam Ferrule, 505- Positive and negative stiffness beam connecting rod, 506- Screw positioning sleeve, 507- Negative stiffness buckling beam connecting right screw, 508- Negative stiffness buckling beam right connecting lug, 509- Negative stiffness buckling beam stress cross plate, 5010- Vibration force, 6-threshing drum, 601-threshing drum body, 602-threshing drum bearing seat, 603-threshing drum shaft, 7-drum top cover, 8- compound beam right connecting piece, 801- compound beam right connecting U shape Sleeve, 802-Prestressed Nut, 803-Prestressed Screw, 9-Complex Beam Left Connector, 901-Complex Beam Left Connection U Sleeve, 902-Left Connection U-Shaped Lug, 902A-Left Connection U-Shaped Lug A , 902B-Left connection U-shaped lug B.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

As shown in Figures 1 and 2, the quasi-zero stiffness compound beam structure for controlling the low-frequency vibration of the longitudinal axial flow threshing drum according to the present invention includes a left column 2, a right column 3, a quasi-zero stiffness compound beam 5, and a right connection of the compound beam 8 and the left connecting piece 9 of the compound beam. The left column 2 and the right column 3 are fixed on the chassis frame. The right side of the quasi-zero stiffness compound beam 5 is connected to the right column 3 through the compound beam right connecting piece 8 , and the left side of the quasi-zero stiffness compound beam 5 is connected to the left column 2 through the compound beam left connecting piece 9 . The threshing drum 6 includes a threshing drum body 601, a threshing drum bearing seat 602, and a threshing drum shaft 603. The upper side of the threshing drum body 601 is the drum top cover 7, and the lower side is the concave plate screen 4; the threshing drum shaft 603 of the threshing drum 6 It is fixed in the middle of the quasi-zero stiffness compound beam 5 by the threshing drum bearing seat 602 .

The quasi-zero stiffness compound beam 5 includes a positive stiffness beam 501, a negative stiffness buckling beam 502, and a positive and negative stiffness beam connecting pad 503. The positive stiffness beam 501 is located on the upper side of the negative stiffness buckling beam 502, and the positive and negative stiffness beam connecting pads 503 Located between positive stiffness beam 501 and negative stiffness buckling beam 502 . The positive stiffness beam 501 is fixedly connected to the middle of the negative stiffness buckling beam 502 .

As shown in FIG. 3, FIG. 4 and FIG. 5, a negative stiffness buckling beam ring 504B is installed in the middle of the upper side of the negative stiffness buckling beam 502, and the right end of the negative stiffness buckling beam 502 is connected to the negative stiffness buckling beam stress transverse plate 509; The negative stiffness buckling beam stress transverse plate 509 is symmetrically installed on the left side with two negative stiffness buckling beam right connecting ears 508, and a screw positioning sleeve 506 is installed at the center of the right side of the negative stiffness buckling beam stress transverse plate 509; the negative stiffness buckling beam The right side of 502 and the right connecting ear 508 of the buckling beam with negative stiffness are fixed by connecting the right screw 507 with the buckling beam with negative stiffness.

As shown in FIG. 6 and FIG. 7 , the compound beam left connecting piece 9 includes a compound beam left connecting U sleeve 901 and a left connecting U-shaped sleeve lug 902. The left and right sides of the compound beam left connecting U sleeve 901 are provided with diameters. It is two through holes of 12mm to 16mm, and the distance between the centers of the two holes is 100mm to 120mm. The left connecting U sleeve 901 of the compound beam is sleeved on the left column 2 , and the left connecting U sleeve 901 of the compound beam is fixed to the left column 2 by two bolts with a diameter of 10mm-14mm. The upper part of the left connecting member 9 of the compound beam is provided with a circular through hole for assembling the cross beam 501 with positive rigidity; The left connecting U-shaped lug 902 is located in the lower part of the right side of the left connecting member 9 of the compound beam, and is respectively the left connecting U-shaped lug A 902A and the left connecting U-shaped lug B 902B, located in the middle of the 2 through holes and installed symmetrically . The distance between the left connecting U-shaped lug A902A and the left connecting U-shaped lug B902B is 6mm to 8mm. The left end of the negative-rigidity flexion beam 502 is annular, located between the left connecting U-shaped lug A 902A and the left connecting U-shaped lug B 902B, and is fixed on the left connecting U-shaped lug 902 by bolts.

As shown in Fig. 8, Fig. 9, Fig. 10, the compound beam right connector 8 includes a compound beam right connecting U-shaped sleeve 801, a prestressed nut 802, and a prestressed screw 803; the compound beam right connecting U-shaped sleeve On the left side of 801, there are 2 through holes with a diameter of 12mm~16mm, the center distance between two adjacent holes is 40mm~60mm, and a square through hole of 6mm × 6mm is opened in the middle of the two through holes; the right side of the compound beam is connected to U Three through holes with diameters of 12mm to 16mm are opened on the right side of the sleeve 801, and the center distance between the adjacent two holes is 40mm to 60mm; 12mm～16mm prestressed nut 802. The right connecting U-shaped sleeve 801 of the compound beam is sleeved on the right column 3, and the right connecting U-shaped sleeve 801 of the compound beam is fixed with the right column 3 by two bolts with a diameter of 10mm to 14 mm; the right connecting U-shaped sleeve 801 of the compound beam The upper part is provided with a circular through hole for assembling the positive rigidity beam 501 , and the right end of the positive rigidity beam 501 penetrates into the circular through hole in the upper left part of the right connecting U-shaped sleeve 801 of the compound beam. The right side of the negative stiffness buckling beam 502 passes through the left square hole of the right connecting U-shaped sleeve 801 of the compound beam, the prestressed screw 803 passes through the prestressed nut 802, and the right column 3 is in contact with the negative stiffness buckling beam stress transverse plate 509, and the prestressed The left end of the screw 803 is limited by the screw positioning sleeve 506 , and the prestressing screw 803 and the prestressing nut 802 are prestressed to apply prestressing to the negative stiffness buckling beam stress transverse plate 509 .

As shown in FIGS. 11 , 12 and 13 , the quasi-positive stiffness beam 501 and the negative stiffness buckling beam 502 are leaf springs with a width of 40mm-60mm, a thickness of 2mm-4mm, and a length of 500mm-600mm; the negative-stiffness buckling beam 502 The left side is bent out of a round hook with an inner diameter of 12mm-16mm, and two through holes with an inner diameter of 12mm-16mm are opened within 25mm of the right edge of the negative stiffness bending beam 502.

The positive stiffness beam ferrule 504A is installed in the middle of the lower side of the positive stiffness beam 501, and the negative stiffness buckling beam ferrule 504B and the positive stiffness beam ferrule 504A are connected by the positive and negative stiffness beam connecting screw 505 to realize the negative stiffness buckling beam 502 and the positive stiffness beam 502. Fixed connection in the middle of the rigid beam 501. The positive and negative stiffness beam connecting screws 505 are U-shaped screws with a diameter of 10 mm to 12 mm. As shown in FIG. 14 , the distance between the centers of the screws at both ends is 50 mm to 60 mm. The positive stiffness beam collar 504A and the negative stiffness buckling beam collar 504B are hollow cylinders with inner diameters of 12mm-16mm, thickness of 2mm, and lengths of 10mm-12mm, as shown in FIG. 15 .

The negative stiffness buckling beam right connecting ear 508 is a steel plate with a shape of 40 mm×60 mm and a thickness of 4 mm to 6 mm, and two through holes of 12 mm to 16 mm are symmetrically opened in the middle, as shown in FIG. 16 . The negative stiffness buckling beam stress transverse plate 509 is a steel plate with a shape of 40mm×60mm and a thickness of 4mm～6mm, as shown in FIG. 17 ; the inner diameter of the screw positioning sleeve 506 is 12mm～16mm, the height is 8mm～10mm, and the thickness is 12mm～16mm. 4mm ~ 6mm steel ring, as shown in Figure 18.

The left connecting U-shaped lug A902A and the left connecting U-shaped lug B 902B are a combination of rectangular and semi-circular steel plates with a thickness of 4 mm to 6 mm, a width of 40 mm to 60 mm, and a height of 50 mm to 60 mm. A section of U-shaped lug B 902B has a through hole with an inner diameter of 12mm to 16mm, as shown in Figure 19. The prestressed screw 803 is a bolt with a diameter of 10 mm to 14 mm and a length of 50 mm to 60 mm, as shown in FIG. 20 .

As shown in Figure 21 and Figure 22, the left column 2 and the right column 3 are square steels with a wall thickness of 2 mm to 3 mm and a cross-sectional shape of 40 mm × 40 mm; 2 through holes, the distance between the centers of the two holes is 100mm to 120mm; there are 3 through holes with diameters of 12mm to 16mm on the left and right sides of the right column 3, and the distance between the centers of the two holes is 40mm to 60mm; the center of the left column 2 is 12mm to 12mm The 16mm through hole is embedded with a prestressed nut 802 with an outer diameter of 12mm-16mm.

As shown in FIG. 23 , the positive stiffness of the positive stiffness beam 501 when it is in the equilibrium position under the action of the dynamic load of the longitudinal axial flow threshing drum 6 where E ₁ is the modulus of elasticity of the beam 501 with positive stiffness, I ₁ is the moment of inertia of the beam 501 with positive stiffness, π is a constant 3.14, and L is the length of the beam 501 with positive stiffness; Negative stiffness when 803 extrusion produces prestress where E ₂ is the elastic modulus of the negative stiffness buckling beam 502 , I ₂ is the inertia moment of the negative stiffness buckling beam 502 , π is a constant 3.14, l is the length of the negative stiffness buckling beam 502 , and k is the negative stiffness buckling beam 502 free state Stiffness; the stiffness k ⁺ +K ^- ≈0 at the equilibrium point of the positive stiffness beam 501 and the negative stiffness buckling beam 502 produces the equilibrium point of the quasi-zero stiffness compound beam 5, and at the equilibrium state of the quasi-zero stiffness compound beam 5, the positive and negative stiffness The beam connecting screw 505 is fixed, and the positive and negative stiffness beam connecting pads 503 are placed in the middle of the equilibrium state of the positive stiffness cross beam 501 and the negative stiffness buckling beam 502 .

As shown in FIG. 24 , the positive stiffness beam 501 includes the left side 501A of the positive stiffness beam and the right side 501B of the positive stiffness beam, and the negative stiffness buckling beam 502 includes the left side 502A of the negative stiffness curved beam and the right side 502B of the negative stiffness curved beam; The cross beam 501 and the negative stiffness buckling beam 502 form a quasi-zero stiffness structural equilibrium point at the positive and negative stiffness beam connection pad 503; When moving upward, the left side 501A of the positive stiffness beam and the right side 501B of the positive stiffness beam are compressed to absorb energy, the left side 502A of the negative stiffness curved beam and the right side 502B of the negative stiffness curved beam are pulled to release energy, and the resultant force at the 5 equilibrium points of the quasi-zero stiffness compound beam It is just in balance with the exciting force 5010; if the equilibrium point of the quasi-zero stiffness compound beam moves downward, the left side 501A of the positive stiffness beam and the right side 501B of the positive stiffness beam are pulled to release energy, and the left side 502A of the negative stiffness curved beam and the negative stiffness curved beam The right side 502B absorbs energy under pressure, and the resultant force at the equilibrium point of the quasi-zero stiffness compound beam 5 is exactly in equilibrium with the excitation force 5010.

The embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above-mentioned embodiments, and any obvious improvement, replacement or All modifications belong to the protection scope of the present invention.

Claims (6)

1. a quasi-zero-stiffness compound beam structure controlling the low-frequency vibration of the longitudinal axial flow threshing drum, is characterized in that, comprises the left column (2) and the right column (3), the quasi-zero-stiffness compound beam ( 5), a right connecting piece of the compound beam (8) and a left connecting piece of the compound beam (9); the quasi-zero-stiffness compound beam (5) includes a positive-stiffness beam (501), a negative-stiffness buckling beam (502), and a positive-negative stiffness beam (502) Beam connection pad (503), the positive stiffness beam (501) is located on the upper side of the negative stiffness buckling beam (502), and the middle of the two is fixedly connected, and the positive and negative stiffness beam connection pad (503) is located on the positive stiffness beam (501) and the middle part of the negative stiffness buckling beam (502); the left and right ends of the quasi-zero stiffness compound beam (5) are respectively connected to the left and On the upright column (2) and the right upright column (3), a prestressing screw (803) is arranged at the right connecting piece (8) of the compound beam, and prestressing is applied to the negative stiffness buckling beam (502); the threshing drum (6) Both ends of the threshing drum shaft (603) are mounted in the middle of the quasi-zero stiffness compound beam (5) through bearing seats (602). 2. The quasi-zero stiffness compound beam structure for controlling the low-frequency vibration of the longitudinal axial flow threshing drum according to claim 1, characterized in that, the positive stiffness beam (501) is in a position under the dynamic load of the longitudinal axial flow threshing drum (6). Positive stiffness at equilibrium position where E ₁ is the elastic modulus of the positive stiffness beam (501), I ₁ is the inertia moment of the positive stiffness beam (501), π is a constant 3.14, L is the length of the positive stiffness beam (501); ) Negative stiffness when the shaft end is extruded by the prestressing screw (803) to produce prestressing where E ₂ is the elastic modulus of the negative stiffness buckling beam (502), I ₂ is the moment of inertia of the negative stiffness buckling beam (502), π is the constant 3.14, l is the length of the negative stiffness buckling beam (502), and k is the negative stiffness buckling beam (502) The stiffness of the buckling beam (502) in the free state; the stiffness k ⁺ +K ^- ≈0 at the equilibrium point of the positive stiffness transverse beam (501) and the negative stiffness buckling beam (502) produces the quasi-zero stiffness compound beam (5) equilibrium point, At the equilibrium state of the quasi-zero stiffness compound beam (5), it is fixed by a positive and negative stiffness beam connecting screw rod (505), and the positive and negative stiffness beam connecting screw rod (505) is a U-shaped screw rod. 3. The quasi-zero stiffness compound beam structure for controlling the low-frequency vibration of the longitudinal axial flow threshing drum according to claim 1, wherein the negative stiffness buckling beam (502) right end is connected with a negative stiffness buckling beam stress transverse plate (509) ), a screw positioning sleeve (506) is provided on the right end surface of the stress transverse plate (509), and the prestressed screw (803) extends into the screw positioning sleeve (506) and is positioned therefrom, and the negative stiffness flexes The left end face of the beam stress transverse plate (509) is provided with a negative stiffness buckling beam right connecting ear (508), and the right end of the negative stiffness buckling beam (502) is connected to the negative stiffness buckling beam right connecting ear (508) through bolts. 4. The quasi-zero stiffness compound beam structure for controlling low-frequency vibration of a longitudinal axial flow threshing drum according to claim 3, wherein the compound beam right connecting piece (8) comprises a compound beam right connecting U-shaped sleeve (801) , the prestressed nut (802), the right connecting U-shaped sleeve (801) of the compound beam is fixed on the right column (3) by 2 bolts; The circular through hole of the rigid beam (501), the prestressing nut (802) is fixed on the right end surface of the right connecting U-shaped sleeve (801) of the compound beam, and the prestressing screw (803) passes through the right upright column (3) and The prestressed nut (802) is connected with the negative stiffness buckling beam stress transverse plate (509); the compound beam left connecting piece (9) includes a compound beam left connecting U sleeve (901) and a left connecting U-shaped sleeve lug (902) , the left connecting U sleeve (901) of the compound beam is fixed on the left column (2) by 2 bolts; the upper part of the left connecting piece (9) of the compound beam is provided with a circular through hole for assembling the beam (501) with positive stiffness; The left end of the bending beam (502) is a circular ring, and is fixed on the left connecting U-shaped lug (902) by bolts; the two ends of the positive stiffness beam (501) are respectively mounted on the left connecting piece (9) of the compound beam and the right connecting piece of the compound beam (902). in the circular through hole of the U-shaped sleeve (801). 5. A quasi-zero stiffness compound beam structure for controlling low-frequency vibration of a longitudinal axial flow threshing drum according to claim 1, wherein the negative stiffness buckling beam (502) is on the upper side of the middle part, and the positive stiffness cross beam (501) The lower side of the middle part is respectively fixed with a negative stiffness buckling beam ring (504B) and a positive stiffness beam ring (504A); the negative stiffness buckling beam ring (504B) and the positive stiffness beam ring (504A) pass through the positive and negative stiffness beams The connecting screw (505) is connected. 6. The quasi-zero stiffness compound beam structure for controlling low-frequency vibration of a longitudinal axial flow threshing drum according to any one of claims 1-5, wherein the positive stiffness beam (501) and the negative stiffness buckling beam (502) ) are leaf springs with a width of 40mm to 60mm, a thickness of 2mm to 4mm, and a length of 500mm to 600mm; the left side of the negative stiffness buckling beam (502) is bent out of a round hook with an inner diameter of 12mm to 16mm, and the negative stiffness buckling beam (502) right edge Two through holes with an inner diameter of 12mm to 16mm are opened at the inner 25mm.