Industrial robot tail end grinding vibration isolator based on quasi-zero stiffness

Abstract

The utility model discloses an industrial robot tail end grinding vibration isolator based on quasi-zero rigidity. The industrial robot tail end grinding vibration isolator comprises an upper static platform, a lower static platform, a positive rigidity mechanism, a negative rigidity mechanism, a load movable platform and a grinding head. The load moving platform is arranged between the upper static platform and the lower static platform in parallel, and the vertical axes of the load moving platform and the static platform coincide. The negative stiffness mechanisms and the positive stiffness mechanisms are vertically arranged between the upper static platform and the lower static platform and are alternately arranged in the circumferential direction. Compression springs on the upper section of the positive stiffness mechanism provide positive stiffness, and horizontal springs distributed in the negative stiffness mechanism in the circumferential direction provide negative stiffness. The three sets of positive stiffness mechanisms are used, so that the three-degree-of-freedom grinding machine has higher load bearing capacity, and the preload needed for grinding a workpiece can be changed by adjusting a locking nut. According to the utility model, positive and negative stiffness are connected in parallel to form a quasi-zero stiffness system, the vibration isolation characteristics of high static stiffness and low dynamic stiffness are realized, and effective isolation of low-frequency vibration and efficient attenuation of high-frequency vibration are realized.

Description

TECHNICAL FIELD

[0001] The utility model belongs to intelligent manufacturing technical field especially relates to an industrial robot end polishing vibration isolator based on quasi-zero stiffness. BACKGROUND

[0002] With the continuous development of industrial robot application technology, how to realize high quality and high efficiency polishing processing has become an important research content in the current industrial robot polishing application. In the industrial robot polishing operation, the polishing executor is easy to cause low-frequency vibration under the action of uncertain external excitation, and long-term vibration will cause mechanical fatigue and part wear, resulting in reduced processing precision and shortened service life. The polishing industrial robot has the problem of insufficient overall stiffness, and the vibration generated will also seriously affect the positioning accuracy of the industrial robot and thus affect the surface quality of the processed parts. Therefore, the vibration of the polishing head of the polishing robot is isolated, and an industrial robot end polishing vibration isolator based on quasi-zero stiffness is designed, which effectively solves the problem of low-frequency vibration generated by the industrial robot end executor during work. This new type of vibration isolator is obtained by parallel combination of positive and negative stiffness, has a quasi-zero stiffness characteristic near the static balance position, has a high static stiffness and low dynamic stiffness characteristic in a small amplitude range, ensures that the entire system has strong carrying capacity while having a low natural frequency, and has good vibration isolation effect.

[0003] The invention patent "Quasi-zero stiffness vibration isolator with unstable simply supported beam as positive stiffness bearing element" with the authorization number CN113323979B discloses a quasi-zero stiffness vibration isolator with an unstable simply supported beam as a positive stiffness bearing element. The quasi-zero stiffness vibration isolator is composed of an unstable simply supported beam as a positive stiffness bearing element and a negative stiffness parallelly connected by a pair of symmetric inclined springs, and can obtain a very low dynamic stiffness without sacrificing its carrying capacity under buckling large deformation conditions, thereby obtaining a larger vibration isolation interval while maintaining excellent carrying performance. Compared with the traditional quasi-zero stiffness vibration isolator, the present invention has not only a lower vibration isolation frequency but also a larger vibration isolation interval. However, the load of this quasi-zero stiffness vibration isolator cannot be self-adaptively adjusted, and the quasi-zero stiffness characteristic can only be realized under a specific load and a specific static deformation, which cannot be applied to occasions with different working loads at the end of the industrial robot.

[0004] The invention patent "Quasi-zero stiffness vibration isolation platform suitable for ultra-low frequency vibration isolation" with the authorization number CN112555317A discloses a quasi-zero stiffness vibration isolation platform suitable for ultra-low frequency vibration isolation, which includes two connecting rod spring assemblies and a central vibration isolation platform assembly. The invention solves the problem that the existing vibration isolation platform uses a linear spring, which has an unsatisfactory vibration isolation effect. The vibration isolation platform is not compact in design and occupies a large area, and the overall system has low static stiffness, which cannot meet the requirements of compact structure and strong carrying capacity of the polishing executor of the industrial robot. Utility model content

[0005] The utility model aims at providing a kind of industrial robot end polishing vibration isolator based on quasi-zero stiffness, to the defects of the quasi-zero stiffness vibration isolation platform applied in industrial robot polishing field, develop a kind of quasi-zero stiffness vibration isolation function's industrial robot end polishing device, adopt 3 groups of positive stiffness mechanism and 3 groups of negative stiffness mechanism quasi-zero stiffness system of alternate parallel along the circumferential direction, with good low-frequency vibration isolation performance, the device compact structure strong bearing capacity, and by adjusting the compression amount of compression spring I realizes polishing pre-pressure adjustable, this parameter is not constrained by system zero stiffness condition, can cope with the scene of different polishing force demand, while in inhibiting vibration and absorbing impact to industrial robot have very significant protective effect.

[0006] To solve the above technical problems, the specific technical scheme of the utility model is as follows:

[0007] In some embodiments of the present application, a kind of industrial robot end polishing vibration isolator based on quasi-zero stiffness is provided, comprising:

[0008] Industrial robot, the flange interface is configured at the end of the industrial robot, for installing actuator;

[0009] Upper and lower static platforms, the upper and lower static platforms are connected to the flange interface at the end of the industrial robot by flange;

[0010] Positive stiffness mechanism, the positive stiffness mechanism is arranged in a circumferential array between the upper and lower static platforms;

[0011] Negative stiffness mechanism, the negative stiffness mechanism is arranged in a circumferential array between the upper and lower static platforms, and it is arranged alternately between the positive stiffness mechanism;

[0012] Load dynamic platform, the load dynamic platform is arranged between the upper and lower static platforms and penetrates the bottom of the lower static platform, and the load dynamic platform is arranged in parallel between the upper and lower static platforms, and the axis is coincident;

[0013] Polishing head, the polishing head is fixedly connected with the load dynamic platform;

[0014] In some embodiments of the present application, the upper and lower static platforms are combined structure, comprising:

[0015] Upper static platform, the upper static platform is provided with upper static platform hole I, upper static platform hole II and upper static platform hole III;Upper static platform hole III is connected with flange;

[0016] Lower static platform, the lower static platform is arranged below the upper static platform, and the two are arranged in parallel and the central axes are coincident, and the lower static platform is provided with lower static platform hole I, lower static platform hole II, and rectangular hole is arranged at the center thereof;

[0017] The top of the positive stiffness mechanism is connected with the upper static platform hole I, and the bottom is connected with the lower static platform hole I;

[0018] The top of the negative stiffness mechanism is connected with the upper static platform hole II, and the bottom is connected with the lower static platform hole II.

[0019] In some embodiments of the application, the positive stiffness mechanism is a combined structure, comprising:

[0020] A vertical guide rod is provided with an upper segment external thread I, an upper segment external thread II and a lower segment external thread arranged in the axial direction, the top of the vertical guide rod penetrates the upper static platform hole I and is connected and fixed by a nut III, the bottom penetrates the lower static platform hole I and is transitionally connected with the lower static platform hole I, and the two are limited by the shaft shoulder at the lower end of the vertical guide rod;

[0021] A locking nut I is arranged on the upper segment external thread II of the vertical guide rod and is located below the upper static platform;

[0022] A locking nut II is arranged on the lower segment external thread of the vertical guide rod and is located above the lower static platform;

[0023] A compression spring I is sleeved on the vertical guide rod and is located below the upper static platform and connected with the bottom of the locking nut I;

[0024] A supporting spring is sleeved on the vertical guide rod and is located above the lower static platform and below the compression spring I and is connected with the top of the locking nut II;

[0025] A linear bearing I is arranged on the vertical guide rod and located between the compression spring I and the supporting spring and is in sliding connection with the vertical guide rod.

[0026] In some embodiments of the application, the negative stiffness mechanism is a combined structure, comprising:

[0027] An intermediate support plate is provided with through holes at the top and the bottom, the top penetrates the upper static platform hole II through a bolt V and is fixedly connected through a nut V, the bottom penetrates the lower static platform hole II through a bolt X and is fixedly connected through a nut X, the center of the intermediate support plate is provided with a U-shaped through groove, and through holes IV and III are symmetrically arranged on both sides of the U-shaped through groove;

[0028] A horizontal guide rod is arranged through the U-shaped through slot of the intermediate support plate, and a horizontal spring is arranged on the horizontal guide rod, one end of the horizontal guide rod is provided with a linear bearing II, and the other end is provided with a mounting ear plate, wherein the linear bearing II is in sliding connection with the horizontal guide rod, the mounting ear plate is in threaded connection with the horizontal guide rod, one end of the horizontal spring is connected with the mounting ear plate, and the other end is connected with the linear bearing II;

[0029] A horizontal guide rod support frame is arranged on the linear bearing II, and the horizontal guide rod support frame is in interference fit with the linear bearing II;

[0030] A single ear seat I is arranged on one side of the horizontal guide rod support frame, is fixedly connected with the intermediate support plate through the bolt IV penetrating the through hole IV and cooperating with the nut IV, and is hingedly connected with the horizontal guide rod support frame through the single ear pin II, wherein the single ear seat I is provided with a rolling bearing at the joint with the horizontal guide rod support frame;

[0031] A single ear seat II is arranged on the other side of the horizontal guide rod support frame, is symmetrically arranged with the single ear seat I, is fixedly connected with the intermediate support plate through the bolt VIII penetrating the through hole III and cooperating with the nut IV, and is hingedly connected with the horizontal guide rod support frame through the single ear pin I, wherein the single ear seat II is provided with a rolling bearing II at the joint with the horizontal guide rod support frame;

[0032] A double ear seat is hingedly connected with the mounting ear plate through a double ear pin, is provided with a double ear countersunk hole on the double ear seat, and is connected with the load movable platform through the screw VIII.

[0033] In some embodiments of the present application, the load movable platform is a combined structure, comprising:

[0034] A load platform is provided with through holes V arranged in a circumferential array and double screw holes II, wherein the through holes V are in interference fit with the linear bearing I, the double screw holes II correspond in position to the double ear countersunk hole, and the load platform is connected with the double ear seat through the screw VIII;

[0035] A right-angle connecting plate is connected with the bottom of the load platform through the screw V;

[0036] A square connecting plate is arranged below the right-angle connecting plate, is fixedly connected with the right-angle connecting plate through the bolt VI and the nut VI, and is connected with the polishing head through the bolt VII and the nut VII.

[0037] In some embodiments of the present application, the right-angle connecting plates are perpendicularly screwed to the load platform in the vertical direction, the axes of the rectangularly-distributed screws V are perpendicular to the lower surface of the load platform, the symmetrically-distributed right-angle connecting plates are perpendicularly connected to the upper surface of the square connecting plate, the countersunk holes and the through holes VIII of the square connecting plate are rectangularly-distributed, and the axis of the bolt VII is perpendicular to the horizontal plane of the square connecting plate; the lower end surface of the square connecting plate is parallel to the upper end surface of the polishing head; the symmetrically-distributed right-angle connecting plates pass through the rectangular hole in the middle of the lower static platform, the side edges of the symmetrically-distributed right-angle connecting plates are parallel to the inner side surface of the rectangular hole, and are located in the middle of the rectangular hole.

[0038] In some embodiments of the present application, the compression amount of the compression spring I is adjustable.

[0039] In some embodiments of the present application, based on the above technical features, a working method of an industrial robot end polishing vibration isolator based on quasi-zero stiffness is disclosed, and the method comprises the following steps:

[0040] Step one, define quasi-zero stiffness working position and initial position

[0041] Quasi-zero stiffness principle: three inclined spring structures provide negative stiffness, and the inclined spring structure with negative stiffness is connected in parallel with three spring structures with positive stiffness to obtain a quasi-zero stiffness system.

[0042] Three horizontal springs with negative stiffness are connected in parallel with three compression springs I with positive stiffness (three horizontal springs collectively provide negative stiffness in the vertical direction), when the polishing head is subjected to a load, the compression spring I and the horizontal spring are compressed to the static equilibrium position, at this time the axis of the horizontal spring is parallel to the upper and lower surfaces of the load platform, the load is completely supported by the compression spring I, at this time the system is a quasi-zero stiffness system, this position is defined as the working position (also called the static equilibrium position), and the system has high static stiffness and low dynamic stiffness near the static equilibrium position. The difference between the original length and the compressed length of the compression spring I defines the vertical spring compression amount, and the positive stiffness coefficient of the compression spring I is determined by Hooke's law.

[0043] When the polishing head is not subjected to load, the load platform is moved downward from the static balance position to the compression spring I just restores to the original length, the load platform is completely supported by the supporting spring, at this time, the axis of the horizontal spring forms a certain initial angle with the horizontal plane (the horizontal spring is inclined), and this position is defined as the initial position. In the case of a certain structural model, reasonable design of the geometric parameters, including the initial angle and the ratio of the stiffness coefficients of the horizontal spring and the compression spring I, can make the system have quasi-zero stiffness characteristics. When designing the model device of the quasi-zero stiffness system, the parameter vertical spring compression amount is adjusted, so that when the required preload of the polishing workpiece is different, the locking nut I can be adjusted to change, at this time, the system is still in the static balance position under the action of the preload. The supporting spring has large rigidity and small deformation, and the supporting load platform is in the initial position.

[0044] Step two, the actual working method of the polishing vibration isolator is described in detail below

[0045] The polishing head is in contact with the workpiece, the reaction force received by the polishing head makes the load platform leave the supporting spring from the initial position to the working position (also called the static balance position), the supporting spring does not provide supporting force, the compression spring I is in the compressed state, the compression amount of the compression spring I can be changed by adjusting the locking nut I to adapt to different loads, when the load moving platform is subjected to low-frequency excitation, the compression spring I provides positive stiffness in the vertical direction, the load platform is vibrated up and down under the action of the polishing excitation force, the articulated horizontal guide rod is swung up and down, the horizontal spring compressed on the guide rod is compressed or stretched to provide negative stiffness in the vertical direction, the load platform is in the state close to 0 stiffness near the balance point, and the quasi-zero stiffness characteristics of the system are realized. The vibration isolator can obtain low system dynamic stiffness on the basis of ensuring high bearing, and has excellent low-frequency vibration isolation performance.

[0046] Compared with the prior art, the polishing vibration isolator has the advantages that:

[0047] The quasi-zero stiffness vibration isolator is developed specially for the polishing field of industrial robots, effectively reduces the harm caused by the vibration of the polishing head through nonlinear stiffness regulation, significantly improves the machining positioning accuracy and the surface quality of the workpiece while protecting the structure of the robot and prolonging the service life. Meanwhile, the polishing vibration isolator has high static stiffness and low dynamic stiffness vibration isolation characteristics, realizes effective isolation of low-frequency vibration and efficient attenuation of high-frequency vibration, and has the characteristics of low initial vibration isolation frequency and wide vibration isolation frequency band.

[0048] The utility model discloses an industrial robot end polishing vibration isolator based on quasi zero stiffness uses upper and lower static platform as support piece, and load dynamic platform is arranged in parallel between upper and lower static platform and is through lower static platform bottom, 3 groups of positive stiffness mechanism and 3 groups of negative stiffness mechanism are alternately arranged in the circumferential array between upper and lower static platform, and the overall structure is compact, and the reliability is high. 3 groups of positive stiffness mechanism make it have higher load bearing capacity. Adjust locking nut to change the preload required for polishing workpiece, and adapt to different working conditions of polishing. BRIEF DESCRIPTION OF DRAWINGS

[0049] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments with reference made to the accompanying drawings. The drawings are for purposes of illustration only and are not intended to be limiting in any respect. Throughout the drawings, the same reference symbols are used for the same components. In the drawings:

[0050] Figure 1 It is a kind of based on quasi zero stiffness of the utility model's industrial robot end polishing vibration isolator overall framework structure schematic diagram;

[0051] Figure 2 It is the utility model Figure 1 A place enlarged structure schematic diagram in the utility model;

[0052] Figure 3 It is a kind of based on quasi zero stiffness of the utility model's industrial robot end polishing vibration isolator structure schematic diagram;

[0053] Figure 4 It is the utility model's positive stiffness mechanism and upper and lower static platform connection schematic diagram;

[0054] Figure 5 It is the utility model's positive stiffness mechanism explosion schematic diagram.

[0055] Figure 6 It is the utility model's negative stiffness mechanism explosion schematic diagram;

[0056] Figure 7 It is the utility model's load dynamic platform explosion structure schematic diagram;

[0057] Figure 8 It is the utility model's upper static platform structure schematic diagram;

[0058] Figure 9 It is the utility model's lower static platform structure schematic diagram;

[0059] Figure 10 It is the utility model's intermediate support plate structure schematic diagram;

[0060] Figure 11 It is the utility model's square connecting plate structure schematic diagram.

[0061] 1, industrial robot; 2, upper and lower static platforms; 3, positive stiffness mechanism; 4, negative stiffness mechanism; 5, load dynamic platform; 6, polishing head; 7, flange; 2-1, upper static platform; 2-2, lower static platform; 2-3, rectangular hole; 2-4, lower static platform hole I; 2-5, lower static platform hole II; 2-6, upper static platform hole III; 2-7, upper static platform hole II; 2-8, upper static platform hole I; 3-1, nut III; 3-2, locking nut I; 3-3, compression spring I; 3-4, vertical guide rod; 3-5, linear bearing I; 3-6, support spring; 3-7, locking nut II; 3-8, upper section outer thread I; 3-9, upper section outer thread II; 3-10, lower section outer thread; 4-1, intermediate support plate; 4-2, single ear seat I; 4-3, horizontal guide rod support frame; 4-4, horizontal guide rod; 4-5, linear bearing II; 4-6, single ear pin I; 4-7, horizontal spring; 4-8, double ear seat; 4-9, screw VIII; 4-10, bolt V; 4-11, nut V; 4-12, bolt IV; 4-13, single ear seat II; 4-14, single ear pin II; 4-15, rolling bearing; 4-16, rolling bearing II; 4-17, nut X; 4-18, bolt X; 4-20, nut IV; 4-21, mounting ear plate; 4-22, double ear pin; 4-23, U-shaped slot; 4-25, through hole IV; 4-26, double ear counterbore hole; 4-27, bolt VIII; 4-28, through hole III; 5-1, load platform; 5-2, right-angle connecting plate; 5-3, nut VII; 5-4, square connecting plate; 5-5, bolt VII; 5-6, bolt VI; 5-7, nut VI; 5-8, through hole VIII; 5-9, counterbore hole; 5-10, screw V; 5-11, through hole V; 5-12, double screw hole II; 7-1, screw VII; 7-2, flange plate; 7-3, bolt IX. DETAILED DESCRIPTION

[0062] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate the present application, but are not used to limit the scope of the present application.

[0063] In order to better understand the purpose, structure and function of the present application, the present application will be further described in detail below with reference to the accompanying drawings.

[0064] Example one, refer to Figures 1-3 The utility model discloses a kind of industrial robot end polishing vibration isolator based on quasi-zero stiffness, including upper and lower static platforms 2, load dynamic platform 5, positive stiffness mechanism 3, negative stiffness mechanism 4, polishing head 6, flange 7, the negative stiffness mechanism 4 with positive stiffness mechanism 3 vertically between upper and lower static platforms, and it is along circumferential direction alternately arranged, the load dynamic platform 5 with upper and lower static platforms 2 parallel arrangement and axis coincides.

[0065] As shown in Figure 4 , Figure 5 , the positive stiffness mechanism 3 includes a locking nut I 3-2, a compression spring I 3-3, a vertical guide rod 3-4, a linear bearing I 3-5, a supporting spring 3-6, a locking nut II 3-7; the compression spring I 3-3 and the supporting spring 3-6 are sleeved on the vertical guide rod 3-4, the linear bearing I 3-5 is clearance fit with the vertical guide rod 3-4 and is between the compression spring I 3-3 and the supporting spring 3-6, the locking nut I is threadedly connected with the upper segment outer thread II 3-9 on the vertical guide rod 3-4, the locking nut I 3-2 is fixedly connected with the upper end of the compression spring I 3-3, the locking nut II 3-7 is fixedly connected with the lower end of the supporting spring 3-6, and the locking nut II 3-7 is threadedly connected with the lower segment outer thread 3-10 of the vertical guide rod 3-4.

[0066] As shown in Figure 6 and Figure 10 , the negative stiffness mechanism 4 includes a double lug seat 4-8, a mounting lug plate 4-21, a horizontal guide rod 4-4, an intermediate support plate 4-1, a horizontal spring 4-7, a horizontal guide rod support frame 4-3, and a single lug seat I 4-2; the double lug seat 4-8 and the mounting lug plate 4-21 are hinged through a double lug pin 4-22, the mounting lug plate 4-21 and the horizontal guide rod 4-4 are threadedly connected, the horizontal guide rod 4-4 passes through a U-shaped through slot 4-23 in the middle of the intermediate support plate 4-1, the horizontal spring 4-7 is sleeved on the horizontal guide rod 4-4, a linear bearing II 4-5 is slidingly connected with the horizontal guide rod 4-4, the linear bearing II 4-5 and a middle through hole of the horizontal guide rod support frame 4-3 are interference fit, the horizontal spring 4-7 is limited between the horizontal guide rod support frame 4-3 and the mounting lug plate 4-21, the single lug seat I 4-2 is hinged with the horizontal guide rod support frame 4-3 through a single lug pin II 4-14, each of the inner side of the single lug seat I 4-2 and the outer side of the horizontal guide rod support frame 4-3 is provided with a rolling bearing 4-15, and the single lug seat I 4-2 is fixed on the intermediate support plate 4-1 through a bolt IV 4-12. A single lug seat II 4-13 is arranged on the other side of the horizontal guide rod support frame 4-3, which is symmetrically arranged with the single lug seat I 4-2, is fixedly connected with the intermediate support plate 4-1 through a bolt VIII 4-27 penetrating a through hole III 4-28 and cooperating with a nut IV 4-20, and is hinged with the horizontal guide rod support frame 4-3 through a single lug pin I 4-6, wherein the single lug seat II 4-13 and the horizontal guide rod support frame 4-3 are provided with a rolling bearing II 4-16 at the joint;

[0067] As shown in Figure 7 and Figure 11As shown, the load moving platform 5 includes a load platform 5-1, a right-angle connecting plate 5-2, and a square connecting plate 5-4. The load platform 5-1 is connected to the right-angle connecting plate 5-2 by screws V 5-10, and the square connecting plate 5-4 is connected to the right-angle connecting plate 5-2 by bolts VI 5-6.

[0068] As shown in Figure 4 , Figure 5 , Figure 8 , Figure 9 As shown, the positive stiffness mechanism 3 is connected to the upper and lower static platforms 2 in the following manner: the lower end of the vertical guide rod 3-4 is transitionally fitted with the lower static platform hole I 2-4, and the two are limited by the shaft shoulder of the lower end of the vertical guide rod. The upper end of the vertical guide rod 3-4 is connected to the upper static platform hole I 2-8 in a threaded manner and is fastened by a nut III 3-1.

[0069] As shown in Figure 5 and Figure 7 As shown, the positive stiffness mechanism 3 is connected to the load moving platform 5 in the following manner: the linear bearing I 3-5 is interference-fitted with the load platform through-hole 5-11, and the linear bearing I 3-5 is slidingly connected on the vertical guide rod 3-4.

[0070] As shown in Figure 6 , Figure 8 , Figure 9 As shown, the negative stiffness mechanism 4 is connected to the upper and lower static platforms 2 in the following manner: the intermediate support plate 4-1 is fixedly connected to the upper static platform 2-1 by the bolt V 4-10 passing through the upper static platform hole II 2-7. The intermediate support plate 4-1 is fixedly connected to the lower static platform 2-2 by the bolt X 4-18 passing through the lower static platform hole II 2-5.

[0071] As shown in Figure 6 and Figure 7 As shown, the negative stiffness mechanism 4 is connected to the load moving platform 5 in the following manner: the screw VIII 4-9 is connected to the double-hole counterbore hole 4-26 provided on the double lug seat 4-8 and the double screw hole II 5-12 on the load platform 5-1.

[0072] As shown in Figure 3 and Figure 11 As shown, the square connecting plate 5-4 is connected to the polishing head 6 by the bolt VII 5-5, and the lower end surface of the flange plate 7-2 is fastened and connected to the upper static platform 2-1 by the bolt IX 7-3 through the circumferentially uniformly distributed bolt mounting holes. The upper end surface of the flange plate 7-2 is circumferentially uniformly provided with connecting hole positions, and the industrial robot 1 is rigidly connected to the end by the screw VII 7-1.

[0073] In addition to all the technical features in embodiment one, embodiment two further comprises: the upper and lower static platforms 2 are disc-like members with coincident axes, the positive stiffness mechanisms 3 are evenly distributed in three groups around the center axis of the upper and lower static platforms, and the vertical guide rods 3-4 have axes parallel to the axes of the upper and lower static platforms, and the load platform 5-1 has three pairs of double screw holes II 5-12 and three through holes V 5-11 evenly and alternately distributed in the circumferential direction.

[0074] The negative stiffness mechanisms 4 are three groups, and the negative stiffness mechanisms 4 are alternately arranged with the positive stiffness mechanisms 3 in the circumferential direction between the upper and lower static platforms 2, the middle support plates 4-1 of the negative stiffness mechanisms 4 are vertically arranged between the upper and lower static platforms 2, and the side surfaces of the middle support plates 4-1 are parallel to the central axes of the upper and lower static platforms 2. The double lug seats 4-8 are three, and there are double screw holes II 5-12 with the double lug seats 4-8 evenly and correspondingly distributed in the circumferential direction of the load platform 5-1, the axes of the screws VIII 4-9 are perpendicular to the central axes of the load platform 5-1, the single lug seat II 4-13 is arranged on the other side of the horizontal guide rod support frame 4-3, the single lug seat I 4-2 and the single lug seat II 4-13 are symmetrically distributed along the axis of the horizontal guide rod 4-4, the horizontal guide rod support frame 4-3 is in the middle of the symmetrically arranged single lug seats, and the axes of the single lug pins I 4-6 and the single lug pins II 4-14 coincide and are perpendicular to the central axes of the horizontal guide rod 4-4 and the load platform 5-1.

[0075] The right-angle connecting plates 5-2 are vertically screwed to the load platform 5-1 in the vertical direction, the axes of the rectangularly distributed screws V 5-10 are perpendicular to the lower surface of the load platform 5-1, the symmetrically distributed right-angle connecting plates 5-2 are vertically connected to the upper surface of the square connecting plate, the countersunk holes 5-9 and the through holes VIII 5-8 of the square connecting plate 5-4 are rectangularly distributed, and the axes of the bolts VII 5-5 are perpendicular to the horizontal plane of the square connecting plate 5-4. The lower end surface of the square connecting plate 5-4 is parallel to the upper end surface of the polishing head 6. The symmetric right-angle connecting plates 5-2 pass through the rectangular hole 2-3 in the middle of the lower static platform 2-2, the side edges of the symmetric right-angle connecting plates 5-2 are parallel to the inner side surfaces of the rectangular hole 2-3, and are in the middle of the rectangular hole 2-3.

[0076] The compression amount of the compression spring I 3-3 is adjustable, so that the polishing pre-pressure between the polishing head and the workpiece is adjustable, and this parameter is not constrained by the system zero stiffness condition.

[0077] Embodiment three, a working method of an industrial robot end polishing vibration isolator based on quasi-zero stiffness comprises the following steps:

[0078] Step one, define quasi-zero stiffness working position and initial position

[0079] Quasi-zero stiffness principle: three inclined spring structures provide negative stiffness, and the inclined spring structures with negative stiffness are connected in parallel with three spring structures with positive stiffness to obtain a quasi-zero stiffness system.

[0080] Three horizontal springs 4-7 with negative stiffness are connected in parallel with three compression springs I 3-3 with positive stiffness (3 horizontal springs together provide negative stiffness in vertical direction), when the polishing head is under load, the compression springs I 3-3 and the horizontal springs 4-7 are compressed to the static equilibrium position, at this time the axis of the horizontal springs 4-7 is parallel to the upper and lower surfaces of the load platform 5-1, the load is completely supported by the compression springs I 3-3, at this time the system is quasi-zero stiffness system, this position is defined as the working position (also known as the static equilibrium position), near the static equilibrium position the system has high static stiffness and low dynamic stiffness. The difference between the original length and the compressed length of the compression springs I 3-3 defines the vertical spring compression amount, the positive stiffness coefficient of the compression springs I 3-3 is determined by Hooke's law.

[0081] When the polishing head is not under load, the load platform 5-1 moves downward from the static equilibrium position to the position where the compression springs I 3-3 just recover to the original length, the load platform is completely supported by the support springs, at this time the axis of the horizontal springs 4-7 forms a certain initial angle with the horizontal plane (the horizontal springs 4-7 are inclined), this position is defined as the initial position. Under certain structural model, reasonable design of geometric parameters including the initial angle and the ratio of the stiffness coefficients of the horizontal springs 4-7 and the compression springs I 3-3, which satisfy certain relationship, can make the system have quasi-zero stiffness characteristics. When designing the model device of the quasi-zero stiffness system, the parameter vertical spring compression amount is adjustable, then when the required preload of the polishing workpiece is different, it can be changed by adjusting the locking nut, at this time the system is still in the static equilibrium position under the action of the preload. The support spring 3-6 has large stiffness and small deformation, and supports the load platform 5 in the initial position.

[0082] Step two, the actual working method of the polishing vibration isolator is described in detail below

[0083] The polishing head 6 is in contact with the workpiece, the reaction force received by the polishing head makes the load platform 5-1 move away from the support spring 3-6 from the initial position to the working position (also known as the static equilibrium position), the support spring does not provide support force, the compression spring I 3-3 is in a compressed state, the compression amount of the compression spring I 3-3 can be changed by adjusting the locking nut I 3-2 to adapt to different loads, when the load platform 5 is under low-frequency excitation, the compression spring I 3-3 provides positive stiffness in the vertical direction, the load platform 5-1 is vibrated up and down under the polishing excitation force, prompting the articulated horizontal guide rod 4-4 to swing up and down, driving the horizontally compressed horizontal springs 4-7 to realize compression or stretching movement to provide negative stiffness in the vertical direction, the load platform 5-1 works near the equilibrium point, the entire system is in a state close to 0 stiffness, realizing the quasi-zero stiffness characteristics of the system. The vibration isolator can obtain low system dynamic stiffness on the basis of ensuring high load capacity, has superior low-frequency vibration isolation performance and high-frequency vibration high-efficiency attenuation.

[0084] In the description of the application, it needs to be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0085] The terms "first", "second" are only for descriptive purpose, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0086] In the description of the application, it needs to be explained that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0087] The embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the device disclosed by the embodiments, since it corresponds to the method disclosed by the embodiments, the description is relatively simple, and the related parts can be referred to the method part description.

[0088] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A quasi-zero stiffness based industrial robot end polishing vibration isolator, characterized by, The industrial robot is provided with a flange interface at the end thereof for mounting an actuator; The upper and lower static platforms are connected to the flange interface at the end of the industrial robot through the flange; The positive stiffness mechanism is arranged in a circumferential array between the upper and lower static platforms; The negative stiffness mechanism is arranged in a circumferential array between the upper and lower static platforms and is arranged alternately with the positive stiffness mechanism; The load dynamic platform is arranged between the upper and lower static platforms and penetrates the bottom of the lower static platform, is arranged in parallel with the upper and lower static platforms and has an axis coincident with the upper and lower static platforms; The polishing head is fixedly connected to the load dynamic platform. The upper and lower static platforms are combined structures and comprise:

2. A quasi-zero stiffness based industrial robot end polishing vibration isolator according to claim 1, characterized in that, The upper static platform is provided with an upper static platform hole I, an upper static platform hole II and an upper static platform hole III, and is connected to the flange through the upper static platform hole III; The lower static platform is arranged below the upper static platform, is arranged in parallel with the upper static platform and has a coincident central axis, is provided with a lower static platform hole I and a lower static platform hole II and is provided with a rectangular hole at the center thereof; The top of the positive stiffness mechanism is connected to the upper static platform hole I and the bottom thereof is connected to the lower static platform hole I; The top of the negative stiffness mechanism is connected to the upper static platform hole II and the bottom thereof is connected to the lower static platform hole II. The positive stiffness mechanism is a combined structure and comprises:

3. A quasi-zero stiffness based industrial robot end polishing vibration isolator according to claim 2, characterized in that, The vertical guide rod is provided with an upper segment external thread I, an upper segment external thread II and a lower segment external thread arranged along the axial direction, the top of the vertical guide rod penetrates the upper static platform hole I and is connected and fixed through a nut III, the bottom of the vertical guide rod penetrates the lower static platform hole I and is connected in transition fit with the lower static platform hole I, and the vertical guide rod is limited by the shaft shoulder at the lower end of the vertical guide rod; The locking nut I is arranged on the upper segment external thread II of the vertical guide rod and is located below the upper static platform; The locking nut II is arranged on the lower segment external thread of the vertical guide rod and is located above the lower static platform; The compression spring I is sleeved on the vertical guide rod, is located below the upper static platform and is connected to the bottom of the locking nut I; The supporting spring is sleeved on the vertical guide rod, is located above the lower static platform and below the compression spring I and is connected to the top of the locking nut II; The linear bearing I is arranged on the vertical guide rod, is located between the compression spring I and the supporting spring and is in sliding connection with the vertical guide rod. The negative stiffness mechanism is a combined structure and comprises:

4. A quasi-zero stiffness based industrial robot end polishing vibration isolator according to claim 3, characterized in that, The intermediate support plate is provided with through holes at the top and bottom thereof, the top of the intermediate support plate penetrates the upper static platform hole II through a bolt V and is fixedly connected through a nut V, the bottom of the intermediate support plate penetrates the lower static platform hole II through a bolt X and is fixedly connected through a nut X, the center of the intermediate support plate is provided with a U-shaped through groove and is provided with a through hole IV and a through hole III arranged in symmetry at the two sides of the U-shaped through groove; ​ Horizontal guide rod, the horizontal guide rod is through the U-shaped through slot of the intermediate support plate, and the horizontal spring is sleeved on the horizontal guide rod, one end of the horizontal spring is provided with linear bearing II, and the other end is provided with mounting lug plate, wherein the linear bearing II is in sliding connection with the horizontal guide rod, the mounting lug plate is in threaded connection with the horizontal guide rod, one end of the horizontal spring is connected with the mounting lug plate, and the other end is connected with the linear bearing II; Horizontal guide rod support frame, the horizontal guide rod support frame is arranged on the linear bearing II, and the horizontal guide rod support frame is in interference fit with the linear bearing II; Single lug seat I, the single lug seat I is arranged on one side of the horizontal guide rod support frame, is fixedly connected with the intermediate support plate through the bolt IV penetrating through the through hole IV and cooperating with the nut IV, and is hinged with the horizontal guide rod support frame through the single lug pin II, wherein the single lug seat I is provided with a rolling bearing at the joint with the horizontal guide rod support frame; Single lug seat II, the single lug seat II is arranged on the other side of the horizontal guide rod support frame, is symmetrically arranged with the single lug seat I, is fixedly connected with the intermediate support plate through the bolt VIII penetrating through the through hole III and cooperating with the nut IV, and is hinged with the horizontal guide rod support frame through the single lug pin I, wherein the single lug seat II is provided with a rolling bearing II at the joint with the horizontal guide rod support frame; Double lug seat, the double lug seat is hinged with the mounting lug plate through the double lug pin, and is provided with a double lug countersunk hole on the double lug seat, and the load movable platform is connected with the double lug seat through the screw VIII.

5. A quasi-zero stiffness based industrial robot end polishing vibration isolator according to claim 4, characterized in that, The load movable platform is a combined structure, comprising: Load platform, the load platform is provided with through holes V arranged in a circumferential array and double screw holes II, wherein the through holes V are in interference fit with the linear bearing I, the double screw holes II correspond to the positions of the double lug countersunk holes, and the load platform is connected with the double lug seat through the screw VIII; Right-angle connecting plate, the right-angle connecting plate is connected with the bottom of the load platform through the screw V; Square connecting plate, the square connecting plate is arranged below the right-angle connecting plate, is fixedly connected with the right-angle connecting plate through the bolt VI and the nut VI, and is connected with the polishing head through the bolt VII and the nut VII.

6. A quasi-zero stiffness based industrial robot end polishing vibration isolator according to claim 5, characterized in that, The right-angle connecting plate is perpendicularly and threadedly connected to the load platform in the vertical direction, the axis directions of the screws V distributed in the rectangular four corners are perpendicular to the lower surface of the load platform, the symmetrically distributed right-angle connecting plates are perpendicularly connected to the upper surface of the square connecting plate, the countersunk holes and the through holes VIII of the square connecting plate are distributed in the rectangular four corners, the axis of the bolt VII is perpendicular to the horizontal plane of the square connecting plate, the lower end surface of the square connecting plate is parallel to the upper end surface of the polishing head, the symmetrically distributed right-angle connecting plates pass through the rectangular hole in the middle of the lower static platform, the side edges of the symmetrically distributed right-angle connecting plates are parallel to the inner side surfaces of the rectangular hole and are located in the middle of the rectangular hole.

7. A quasi-zero stiffness based industrial robot end polishing vibration isolator according to claim 3, characterized in that, The compression amount of the compression spring I is adjustable.

Images