CN117167428A - Variable damping vibration attenuation device for industrial robot cutting machining and vibration attenuation method thereof - Google Patents
Variable damping vibration attenuation device for industrial robot cutting machining and vibration attenuation method thereof Download PDFInfo
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Abstract
The invention provides a variable damping vibration attenuation device for industrial robot cutting machining and a vibration attenuation method thereof, and relates to the technical field of industrial robot vibration attenuation. An excitation coil is wound in a side wall groove of the outer ring framework, an outer ring shell is sleeved outside the outer ring framework, and a magnetorheological sponge layer is sleeved in a central round hole of the outer ring framework; an inner ring is sleeved on the inner side of the magnetorheological sponge layer; the inner side of the inner ring is sleeved with a high-speed bearing; a sleeve is sleeved in the inner ring of the high-speed bearing. The connecting bracket and the knife handle are connected with the industrial robot end effector spindle in an installation mode, so that the damping effect of the robot end effector can be changed to consume vibration energy generated at the knife handle in the robot cutting process, transmission of vibration in a robot cutting system structure is reduced, the current in the exciting coil is controlled according to the change of external excitation under different working conditions, the damping characteristic of the robot end effector is adjusted in real time, better damping effect is obtained, and the machining stability is improved.
Description
Technical Field
The invention relates to the technical field of vibration reduction of industrial robots, in particular to a variable damping vibration reduction device for cutting processing of an industrial robot and a vibration reduction method of the variable damping vibration reduction device.
Background
Industrial robots have become key equipment for automated and intelligent production in modern manufacturing industries. Compared with the traditional multi-axis machining center, the industrial robot machining system has the advantages of good space accessibility, high flexibility degree, high machining efficiency, portability, quick reconstruction and better machining adaptability, and is increasingly applied to the manufacturing fields of aviation, aerospace, ships, vehicles, wind power and the like, and the industrial robot machining system replaces manual work to finish milling, drilling, grinding, boring, cutting and the like. However, due to the inherent characteristics of the industrial robot, the structural rigidity of the processing system formed by the industrial robot is weak (only 1/50 of that of a machine tool), the industrial robot is easily affected by cutting acting force and disturbance in the cutting processing process, obvious vibration is generated, and even chatter is generated in severe cases, so that the processing quality is reduced, and even the serious consequences of product scrapping or robot damage are caused. Therefore, in order to realize high-precision, efficient and high-quality manufacturing, the problems of vibration control and chatter of the robot cutting process need to be solved. The existing robot processing vibration damping method can be divided into: passive control, active control, and semi-active control. The passive control changes the dynamic characteristics of the processing system by introducing various passive vibration damping mechanisms or auxiliary systems, the vibration damping structure is simple, the realization difficulty is low, but the working frequency bandwidth is small, the vibration damping response to external excitation with complex and changeable frequency is poor, and the efficiency and the flexibility for adapting to different working conditions are lacking. The active control has the input of external energy, can effectively inhibit the vibration and flutter problems in the cutting process of the robot, but has high requirements on hardware and software, complex implementation process, large energy consumption, high cost and lower engineering application feasibility.
The magnetorheological material is an intelligent material with a magnetorheological effect, and is characterized in that when the magnetorheological material is continuously acted by an external magnetic field, the rheological property and the viscoelasticity of the magnetorheological material can change rapidly (in the order of 10 ms) continuously and reversibly (after the external magnetic field is removed, the original state is restored). Therefore, the variable damping self-adaptive vibration damper can be researched based on magneto-rheological materials and applied to the cutting machining vibration suppression of robots. The semi-active control vibration reduction method based on the magnetorheological material can control the absorption/damage degree of system vibration by changing the amount of external input energy, achieves the effect and advantage of approaching active control, and has lower cost and difficulty.
The Chinese patent with the publication number of CN107477139B discloses a transducer which can be used for vibration reduction of a robot, and particularly discloses a vibration isolator provided with a spring channel, a damping removing channel and a damping buffering channel, wherein the device can realize free switching of liquid damping vibration isolation and solid spring stiffness vibration isolation energy.
And as another example, chinese patent with publication number CN112454382B discloses an "industrial robot cutting processing variable stiffness self-adaptive vibration damping system", which specifically discloses a magnetorheological elastomer vibration isolator installed at a robot flange.
And as a Chinese patent with the publication number of CN209157166U discloses a magneto-rheological vibration-inhibiting intelligent knife handle system, in particular to a magneto-rheological fluid-based intelligent knife handle with variable rigidity and damping.
The defects of the prior art are as follows: 1) The traditional damping shock absorber has single structural damping characteristic, is fixed, belongs to a passive damping mode, has an unobvious damping effect, and has lower damping efficiency in the face of incapability of adjusting the damping effect of a system due to complex and changeable dynamic environment excitation in the cutting machining process of a robot; 2) The cutting and machining vibration of the robot is directly from external excitation applied when the end effector contacts with a workpiece, and the principle of the vibration isolator is that the vibration isolator is isolated from a vibration source by a vibration isolation system to reduce the influence and propagation of the vibration, so that the vibration isolator is not suitable for being applied to a vibration reduction scene of the end effector in the machining of the robot; 3) The magnetorheological fluid is packaged in rotary structures such as a cutter handle, so that the sealing difficulty and the sealing requirement of the magnetorheological fluid are greatly increased, the sedimentation problem of the magnetorheological fluid is accelerated due to the action of centrifugal force, the magnetorheological fluid is invalid, and the stability is poor; 4) The magneto-rheological fluid, the exciting coil and other processing structures such as the cutter handle and the cutter bar are integrated into a whole, so that the complexity of the structure is greatly increased, the manufacturing cost is high, the period is long, the inspection and replacement in the use process are inconvenient, especially, the magneto-rheological fluid, the exciting coil and other processing structures need to be manufactured again when the magneto-rheological fluid is damaged, the cost is high, the production efficiency is easy to influence, and in addition, the difficulty in developing dynamic balance test and compensation for the cutter handle and other parts is high, the cost is high, the period is long, the stability is poor, so that the magneto-rheological fluid and the exciting coil are unfavorable for popularization and popularization.
Disclosure of Invention
The invention aims to: a variable damping vibration attenuation device for industrial robot cutting processing is provided, and a damping vibration attenuation method of the variable damping vibration attenuation device for industrial robot cutting processing is further provided, so as to solve the problems in the prior art.
The technical scheme is as follows: in a first aspect, the invention provides a variable damping vibration attenuation device for industrial robot cutting machining, which comprises an outer ring framework, an outer ring shell, an exciting coil, a magnetorheological sponge layer, an inner ring, an upper end cover, a lower end cover, a high-speed bearing and a sleeve.
The exciting coil is wound in a side wall groove of the outer ring framework, the outer ring casing is sleeved outside the outer ring framework, the magnetorheological sponge layer is sleeved in a central round hole of the outer ring framework, the inner ring is sleeved inside the magnetorheological sponge layer, the upper end cover and the lower end cover are respectively arranged at the upper end and the lower end of the inner ring, the high-speed bearing is sleeved inside the inner ring, and the sleeve is sleeved in an inner ring of the high-speed bearing.
The device can adjust the output of an external adjustable current source according to the vibration condition of the robot cutting system under external excitation of different working conditions, further control the current in the exciting coil, change the magnetic field intensity generated by the exciting coil, further change the shearing yield strength and viscosity of magnetorheological fluid in the magnetorheological sponge layer, finally change the performance of the magnetorheological sponge layer for generating damping effect, realize the adjustment of generated damping force, effectively reduce the robot machining vibration, and improve the adaptability and the machining stability of the robot cutting system under different working conditions and environments.
In a further embodiment of the first aspect, the edge of the upper surface and the lower surface of the outer ring framework are respectively and uniformly provided with 8 countersunk through holes and 8 threaded holes, and the countersunk through holes and the 8 threaded holes are respectively and uniformly distributed on the upper surface and the lower surface of the side wall of the outer ring shell and are connected through bolt matching; 4 threaded holes are uniformly distributed at the upper end and the lower end of the inner ring respectively and are connected with the upper end cover and the lower end cover through bolts respectively; fixing holes matched with bolts are uniformly distributed at the edges of the upper end cover and the lower end cover, and positioning bosses respectively contacted with 2 high-speed bearings are arranged on the inner sides of the upper end cover and the lower end cover; the high-speed bearing outer ring is in interference fit with the inner ring, and the inner ring is in interference fit with the sleeve; the middle part of the sleeve is provided with positioning shaft shoulders which are contacted with the inner rings of the 2 high-speed bearings; the magnetorheological sponge layer is adhered and filled in a gap between the inner hole wall of the outer ring framework and the outer surface of the inner ring.
In a further embodiment of the first aspect, the vibration reduction device is installed and connected with a main shaft of an end effector of the industrial robot through a connecting bracket and a cutter handle, 8 through holes uniformly distributed at the lower end of the connecting bracket are fixedly connected with the outer ring framework through bolts, 8 threaded holes matched with the bolts are uniformly distributed on the upper surface of the outer ring framework close to the central round hole side, and a section of boss with a concentric positioning function is also arranged on the upper surface of the outer ring framework and is in clearance fit with the round hole at the lower end of the connecting bracket; and 4 through holes are uniformly distributed at one end of the side wall of the sleeve along the circumferential direction and are connected with the cutter handle through bolts, and 4 threaded holes matched with the bolts are uniformly distributed at the side wall of the cutter handle along the circumferential direction.
In a further embodiment of the first aspect, after the vibration reduction device is installed and connected with the industrial robot end effector spindle through the connection bracket and the tool handle, it is required to ensure that the upper end surfaces or the lower end surfaces of the outer ring skeleton, the magnetorheological sponge layer and the inner ring are on the same plane; the connecting support is characterized in that a baffle plate connected through a screw is arranged on a connecting surface, which is close to the outer ring framework, of the inner side of the connecting support, a stop rod with the diameter of 3mm protrudes from the upper surface of the outer side of the upper end cover, a round hole with the diameter of 5mm is arranged on the baffle plate to hook the stop rod to apply a pulling force to the outer ring of the high-speed bearing, the inner ring, the upper end cover and the lower end cover to prevent the upper end cover from following the rotation of the cutter handle.
In a further embodiment of the first aspect, the exciting coil is connected to an external adjustable current source through a wire, and the side wall of the outer ring casing is provided with a notch for cooperation with the wire.
In a further embodiment of the first aspect, the magnetorheological sponge layer is manufactured by impregnating the polyurethane sponge with the magnetorheological fluid for more than 7 hours, and after the impregnating, the magnetorheological sponge layer should be repeatedly extruded until the magnetorheological sponge layer hangs in the air, and no more magnetorheological fluid overflows and drops.
In a further embodiment of the first aspect, the material of the connecting bracket, the baffle plate, the stop lever, the upper end cover and the lower end cover is an aluminum alloy; the material of the cutter handle is 20CrMnTi; the outer ring framework, the outer ring shell and the inner ring are made of electromagnetic pure iron or Q235 steel with high magnetic permeability, high magnetic saturation strength and low coercivity; the sleeve is made of 45# steel; the bolts are made of nonmagnetic steel.
In a further embodiment of the first aspect, the output of the external adjustable current source can be adjusted according to the vibration condition of the robot cutting system under external excitation of different working conditions, so that the current in the exciting coil is controlled, the strength of the magnetic field generated by the exciting coil is changed, the shear yield strength and viscosity of the magnetorheological fluid in the magnetorheological sponge layer are changed, finally the damping effect generating performance of the magnetorheological sponge layer is changed, the generated damping force is adjusted, the robot machining vibration is effectively reduced, and the adaptability and the machining stability of the robot cutting system under different working conditions and environments are improved.
In a second aspect, a vibration reduction method of a variable damping vibration reduction device for industrial robot cutting machining is provided, and the working process of the vibration reduction device comprises the following steps: the vibration displacement/speed/acceleration and cutting force of the cutter point in the cutting process of the robot are monitored through the sensor, the input current of the vibration damper is controlled by an external adjustable current source according to the vibration condition of the cutter point, and then the damping force output of the vibration damper is changed.
In a further embodiment of the first aspect, the tool axial cutting force F is determined at this time Z With maximum tool radial cutting force F XY Axial vibration amplitude S of the knife point Z (displacement/speed/acceleration) and maximum nose point radial vibration amplitude S XY The relation conditions between (displacement/speed/acceleration) include condition a, corresponding to process flow a'; condition B corresponds to process flow B'.
In a further embodiment of the first aspect, condition a: if the axial cutting force F of the tool during the cutting process of the robot Z Significantly greater than the maximum tool radial cutting force F XY And at this time the axial vibration amplitude S of the knife point Z Radial vibration amplitude S which is obviously larger than the maximum point of the tool nose XY Executing a processing flow A':
according to the analysis of the balance condition of the tool nose point, the vibration damper needs to output the expected damping force F e From the formulaAnd (5) determining. Judging the relation condition between the expected damping force and the range of the damping force which can be output by the vibration reduction device under the limit of the safety current, wherein the relation condition comprises a condition C and a corresponding processing flow C'; condition D, correspond toProcess flow D'.
In a further embodiment of the first aspect, condition B: if the axial cutting force F of the tool during the cutting process of the robot Z Less than/about equal to the maximum tool radial cutting force F XY Or axial vibration amplitude S of the tool nose point at the moment Z Radial vibration amplitude S less than/about equal to maximum nose point XY Executing a processing flow B':
according to the knife point balance condition analysis and the moment equivalent principle, the vibration damper needs to output the expected damping force F e From the formulaCalculation and determination, wherein L o Is the axial distance L between the end face of the outer ring shell and the tail end of the knife handle d Is the axial length of the magnetorheological sponge layer. Judging the relation condition between the expected damping force and the range of the damping force which can be output by the vibration reduction device under the limit of the safety current, wherein the relation condition comprises a condition C and a corresponding processing flow C'; condition D, corresponds to process flow D'.
In a further embodiment of the first aspect, condition C: if the desired damping force F of the vibration damper is during the cutting operation of the robot e Within the range of the exportable damping force, process flow C' is performed:
adjusting the current input of an external adjustable current source to the vibration damper to enable the output damping force of the vibration damper to be equal to the expected damping force F e The same applies.
In a further embodiment of the first aspect, condition D: if the desired damping force F of the vibration damper is during the cutting operation of the robot e Outside the range of exportable damping forces, process flow D' is performed:
and adjusting the wire diameter of the exciting coil, the polyurethane sponge density of the magnetorheological sponge layer and the magnetorheological fluid content in the vibration damper to expand or adjust the range of the output damping force. Or the current input of the external adjustable current source to the vibration damper is regulated to be a critical value of safety limit, so that the output damping force of the vibration damper reaches a limit value, and the maximum vibration damper effect is realized.
The beneficial effects of the invention are as follows:
1) According to the external excitation of the robot and the change of the vibration condition of the end effector in the cutting process, the damping device can conveniently adjust the damping characteristic of the end effector of the robot in real time by matching with a proper measuring means and a damping method, so that proper damping force is output in the processing process, high-efficiency and adaptively-changed damping vibration reduction is realized, and the cutting process vibration of the robot is effectively reduced;
2) Because the radial rigidity of the end effector spindle is weaker than that of the axial direction, the radial vibration of the end effector spindle is taken as the main vibration during robot processing, the vibration damper is integrally in a ring shape to wrap the tool handle, the radial vibration of the spindle can be effectively restrained, the vibration damper is structurally symmetrical in center, and the vibration damper is convenient to connect with the robot end effector spindle and is beneficial to the stability during robot processing;
3) The damping device adopts polyurethane sponge as a carrier of the magnetorheological fluid, so that the sedimentation problem of the magnetorheological fluid can be effectively solved, the sealing requirement on the magnetorheological fluid is obviously reduced, and the inspection period and the service life of the damping device are obviously optimized;
4) The vibration damper and the cutter handle are combined and matched for use, the vibration damper is separable, the requirements for manufacturing and dynamic balance are low, the cutter handle can be put into production as soon as possible only by replacing the cutter handle when the cutter handle is damaged, the damping vibration damper is not easy to damage the damping vibration damper in a linked manner, and the vibration damper is favorable for long-term use.
Drawings
Fig. 1 is a sectional view of a variable damping vibration attenuation device, a connecting bracket and a tool shank for industrial robot cutting machining.
Fig. 2 is a schematic view of the installation and principle of the device of the invention.
Fig. 3 is a schematic perspective view of a variable damping vibration attenuation device for industrial robot cutting machining, a connecting bracket and a tool shank according to an embodiment of the present invention.
Fig. 4 is an isometric view of a variable damping vibration attenuation device for industrial robot cutting according to another embodiment of the present invention.
Fig. 5 is a schematic perspective view of a variable damping vibration attenuation device for industrial robot cutting according to another embodiment of the present invention.
Fig. 6 is a functional block diagram of a variable damping vibration attenuation device for industrial robot cutting processing according to the present invention.
The reference numerals in the drawings are as follows: the robot end effector spindle 1, the connecting bracket 2, the variable damping vibration attenuation device 3, the tool shank 4, the lead 5, the outer ring framework 6, the outer ring shell 7, the magnetorheological sponge layer 8, the inner ring 9, the sleeve 10, the baffle 11, the upper end cover 12, the exciting coil 13, the high-speed bearing 14, the lower end cover 15 and the stop lever 16.
Detailed Description
In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without one or more of these details. In other instances, well-known features have not been described in detail in order to avoid obscuring the invention.
Referring to fig. 1-5, the present embodiment provides a variable damping device 3 for industrial robot cutting, which includes a wire 5, an outer ring frame 6, an outer ring housing 7, a magnetorheological sponge layer 8, an inner ring 9, a sleeve 10, a baffle 11, an upper end cover 12, an exciting coil 13, a high-speed bearing 14, a lower end cover 15, and a stop lever 16. The three-dimensional structural design of the variable damping vibration reduction device 3 for the industrial robot cutting machining is in a circular ring shape, so that the tool handle 4 can be wrapped, radial vibration of the main shaft 1 of the end effector of the robot is effectively restrained, and the variable damping vibration reduction device 3 for the industrial robot cutting machining is installed and connected with the main shaft 1 of the end effector of the industrial robot through the connecting bracket 2 and the tool handle 4; eight through holes uniformly distributed at the lower end of the connecting bracket 2 are fixedly connected with the outer ring framework 6 through bolts, eight threaded holes matched with the bolts are uniformly distributed on the upper surface of the outer ring framework 6 close to the central round hole side, and a section of boss with a concentric positioning function is also arranged on the upper surface of the outer ring framework 6 and is in clearance fit with the round hole at the lower end of the connecting bracket 2; four through holes are uniformly distributed at one end of the side wall of the sleeve 10 along the circumferential direction and are connected with the cutter handle 4 through bolts, and four threaded holes matched with the bolts are uniformly distributed at the side wall of the cutter handle 4 along the circumferential direction; the connecting surface, which is close to the outer ring framework 6, of the inner side of the connecting bracket 2 is provided with a baffle plate 11 connected through screws, the upper surface of the outer side of the upper end cover 12 is protruded with a stop lever 16 with the diameter of 3mm, and a round hole with the diameter of 5mm is arranged on the baffle plate 11 to hook the stop lever 16 so as to apply a pulling force for preventing the outer ring, the inner ring 9, the upper end cover 12 and the lower end cover 15 of the high-speed bearing 14 from rotating along with the knife handle 4.
An excitation coil 13 is wound in a side wall groove of the outer ring framework 6, the winding number of turns reaches 800-1000 turns, an outer ring shell 7 is sleeved outside the outer ring framework 6, the excitation coil 13 is connected with an external adjustable current source through a lead 5, a notch matched with the lead 5 for use is formed in the side wall of the outer ring shell 7, a magnetorheological sponge layer 8 is sleeved in a central round hole of the outer ring framework 6, an inner ring 9 is sleeved on the inner side of the magnetorheological sponge layer 8, an upper end cover 12 and a lower end cover 15 are respectively arranged at the upper end and the lower end of the inner ring 9, two high-speed bearings 14 are sleeved on the inner side of the inner ring 9, and a sleeve 10 is sleeved in the inner ring of the high-speed bearings 14; eight countersunk through holes and eight threaded holes are respectively and uniformly distributed on the edge of the upper surface and the lower surface of the outer ring framework 6, and the eight countersunk through holes are respectively and uniformly distributed on the upper surface of the side wall of the outer ring shell 7 and the eight through holes are respectively and uniformly distributed on the lower surface of the side wall of the outer ring shell 7 and are connected through bolt matching; four threaded holes are uniformly distributed at the upper end and the lower end of the inner ring 9 and are respectively connected with the upper end cover 12 and the lower end cover 15 through bolts; fixing holes matched with bolts are uniformly distributed at the edges of the upper end cover 12 and the lower end cover 15, and positioning bosses respectively contacted with the two high-speed bearings 14 are arranged on the inner sides of the upper end cover and the lower end cover; the outer ring of the high-speed bearing 14 is in interference fit with the inner ring 9, and the inner ring is in interference fit with the sleeve 10; the middle part of the sleeve 10 is provided with a positioning shaft shoulder which is contacted with the inner rings of the two high-speed bearings 14; the magnetorheological sponge layer 8 is adhered and filled in a gap between the inner hole wall of the outer ring framework 6 and the outer surface of the inner ring 9.
In terms of material selection, the connecting bracket 2, the baffle 11, the stop lever 16, the upper end cover 12 and the lower end cover 15 are made of aluminum alloy; the material of the cutter handle 4 is 20CrMnTi; the outer ring framework 6, the outer ring shell 7 and the inner ring 9 are made of electromagnetic pure iron or Q235 steel with high magnetic permeability, high magnetic saturation strength and low coercivity; the sleeve 10 is made of 45# steel; the bolts are made of non-magnetic steel; the magnetorheological sponge layer 8 is prepared by impregnating the magnetorheological fluid into polyurethane sponge for more than 7 hours, and after the magnetorheological sponge layer 8 is impregnated, the magnetorheological fluid is repeatedly extruded until the magnetorheological fluid is suspended in the air, so that no more magnetorheological fluid overflows and drops; the thickness of the magnetorheological sponge layer 8 is 2-3 mm; the density of polyurethane sponge selected in the magnetorheological sponge layer 8 is up to 40-70; the density of the magnetorheological fluid selected in the magnetorheological sponge layer 8 is 3.65-4.05, the working temperature is-40-140 ℃, the viscosity is 0.280+/-0.070 Pa-s (800-1200 sec-1, 40 ℃), the weight percentage of the magnetic powder is more than or equal to 80%, the volume percentage is more than 40%, and the shear yield strength of the magnetorheological fluid is more than or equal to 40kPa when the magnetic field strength of the magnetorheological fluid reaches 80 kAmp/m.
During operation, the industrial robot cutting processing variable damping vibration attenuation device 3 needs to be installed firstly: firstly, pressing a high-speed bearing 14 into a sleeve 10, ensuring that the inner ring of the high-speed bearing 14 is in interference fit with the outer side wall of the sleeve 10 and abuts against a shaft shoulder on the sleeve 10; then, the upper end cover 12 is connected with the inner ring 9 through bolts, a temporary combination body of the high-speed bearing 14 and the sleeve 10 is pressed into the inner ring 9, interference fit between the outer ring of the high-speed bearing 14 and the inner side wall of the inner ring 9 is ensured, the boss on the upper end cover 12 is abutted, and then the lower end cover 15 is connected with the other side of the inner ring 9 through bolts; then, sleeving the tool handle 4 into the sleeve 10 in the assembled assembly, and connecting the tool handle 4 with the sleeve 10 through bolts to ensure transition fit; finally, the tail part of the knife handle 4 is mounted on a main shaft of an end effector of the robot, and the magnetorheological inner ring 9 is partially assembled. The magnetorheological sponge layer 8 is coated on the outer side wall of the inner ring 9 and is bonded by an adhesive. Simultaneously, the exciting coil 13 is wound into a side wall groove of the outer ring framework 6, and then the outer ring framework 6 is connected with the outer ring shell 7 through bolts; the head of the exciting coil 13 penetrates out of the opening of the side wall of the outer ring shell 7 and is connected with an external adjustable current source through a lead 5; and finally, the outer ring framework 6 is connected with the connecting bracket 2 through bolts, so that the outer ring part of the magnetorheological damper is assembled. And finally, hanging the connecting support 2 of the outer ring part of the magnetorheological damper on a main shaft of an end effector of the robot through bolts, and finishing the installation and connection of the variable damping vibration damper 3 in the cutting processing of the whole industrial robot.
In the process of cutting processing of the industrial robot, an external adjustable current source synchronously operates, the inner rings of the sleeve 10 and the high-speed bearing 14 rotate along with the cutter handle 4 for clamping a processing cutter, the rest parts of the variable damping vibration reduction device 3 for cutting processing of the industrial robot, the main shaft 1 of the end effector of the robot and the connecting bracket 2 are kept relatively static, the inner ring 9 is driven to extrude the magnetorheological sponge layer 8 between the inner ring 9 and the outer ring framework 6 when the cutter handle 4 vibrates, and then the magnetorheological sponge layer 8 outputs reverse damping force to the inner ring 9 and the cutter handle 4 to dissipate the vibration energy; according to the vibration condition of the robot cutting system under the current external excitation, the output current of an external adjustable current source can be adjusted in real time through terminals such as an upper computer, a DSP (digital signal processor) controller and the like by matching with a certain measuring means and a vibration reduction method, namely, the current size in an exciting coil 13 in the variable damping vibration reduction device 3 for industrial robot cutting is changed, and then the magnetic field intensity generated by the exciting coil 13 is changed, so that the shearing yield strength and the viscosity of magnetorheological fluid in a magnetorheological sponge layer 8 are changed, the damping force generated by the magnetorheological sponge layer 8 and applied to a cutter handle 4 is finally changed, and the radial vibration of the cutter handle 4 in the cutting process is furthest restrained. In the industrial robot cutting process, the tool shank 4 directly clamps the tool to cut a workpiece, is directly excited by external cutting force, is the most main vibration source of robot vibration, and can effectively reduce the vibration at the tool shank 4 and further transmit the vibration to the structures such as the main shaft 1 of the end effector of the robot, the industrial robot body and the like, so that the vibration of a robot cutting system is reduced, and the stability of the robot cutting process and the processing quality of the workpiece are improved.
Based on the variable damping vibration attenuation device 3 for industrial robot cutting provided in the above embodiment, this embodiment further discloses a vibration attenuation method of the variable damping vibration attenuation device 3 for industrial robot cutting, see fig. 6. The working process of the vibration damper comprises the following steps: the vibration displacement/speed/acceleration and cutting force of the cutter point in the cutting process of the robot are monitored through the sensor, the input current of the vibration damper is controlled by an external adjustable current source according to the vibration condition of the cutter point, and then the damping force output of the vibration damper is changed.
Judging the axial cutting force F of the cutter at the moment Z With maximum tool radial cutting force F XY Axial vibration amplitude S of the knife point Z (displacement/speed/acceleration) and maximum nose point radial vibration amplitude S XY The relation conditions between (displacement/speed/acceleration) include condition a, corresponding to process flow a'; condition B corresponds to process flow B'.
Condition a: if the axial cutting force F of the tool during the cutting process of the robot Z Significantly greater than the maximum tool radial cutting force F XY And at this time the axial vibration amplitude S of the knife point Z Radial vibration amplitude S which is obviously larger than the maximum point of the tool nose XY Executing a processing flow A':
according to the analysis of the balance condition of the tool nose point, the vibration damper needs to output the expected damping force F e From the formulaAnd (5) determining. Judging the relation condition between the expected damping force and the range of the damping force which can be output by the vibration reduction device under the limit of the safety current, wherein the relation condition comprises a condition C and a corresponding processing flow C'; condition D, corresponds to process flow D'.
Condition B: if the axial cutting force F of the tool during the cutting process of the robot Z Less than/about equal to the maximum tool radial cutting force F XY Or axial vibration amplitude S of the tool nose point at the moment Z Radial vibration amplitude S less than/about equal to maximum nose point XY Executing a processing flow B':
according to the knife point balance condition analysis and the moment equivalent principle, the vibration damper needs to output the expected damping force F e From the formulaCalculation and determination, wherein L o Is the axial distance L between the end face of the outer ring shell 7 and the tail end of the knife handle 4 d Is the axial length of the magnetorheological sponge layer 8. Judging the relation condition between the expected damping force and the range of the damping force which can be output by the vibration reduction device under the limit of the safety current, wherein the relation condition comprises a condition C and a corresponding processing flow C'; condition D, corresponds to process flow D'.
Condition C: if the desired damping force F of the vibration damper is during the cutting operation of the robot e At the site ofWithin the range of the output damping force, the process flow C' is executed:
adjusting the current input of an external adjustable current source to the vibration damper to enable the output damping force of the vibration damper to be equal to the expected damping force F e The same applies.
Condition D: if the desired damping force F of the vibration damper is during the cutting operation of the robot e Outside the range of exportable damping forces, process flow D' is performed:
and (3) adjusting the wire diameter of the exciting coil 13, the polyurethane sponge density and the magnetorheological fluid content of the magnetorheological sponge layer 8 in the vibration damper to expand or adjust the range of the damping force capable of being output. Or the current input of the external adjustable current source to the vibration damper is regulated to be a critical value of safety limit, so that the output damping force of the vibration damper reaches a limit value, and the maximum vibration damper effect is realized.
As described above, although the present invention has been shown and described with reference to certain preferred embodiments, it is not to be construed as limiting the invention itself. Various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (12)
1. The utility model provides a variable damping vibration damper for industrial robot cutting process which characterized in that includes:
an outer ring skeleton;
the exciting coil is wound in the side wall groove of the outer ring framework;
the outer ring shell is sleeved on the outer side of the outer ring framework;
the magnetorheological sponge layer is sleeved in the central round hole of the outer ring framework; an inner ring is sleeved on the inner side of the magnetorheological sponge layer;
an upper end cover and a lower end cover are respectively arranged at the upper end and the lower end of the inner ring; the inner side of the inner ring is sleeved with a high-speed bearing, and the inner ring of the high-speed bearing is sleeved with a sleeve;
the vibration reduction device is connected with the industrial robot end effector spindle through the connecting bracket and the knife handle;
the exciting coil is connected with an external adjustable current source through a wire; and adjusting the output of an external adjustable current source according to the vibration condition under the external excitation of different working conditions, further controlling the current in the exciting coil, and changing the intensity of a magnetic field generated by the exciting coil, thereby changing the shear yield strength and viscosity of magnetorheological fluid in the magnetorheological sponge layer and finally changing the damping of the magnetorheological sponge layer.
2. The variable damping vibration attenuation device for industrial robot cutting machining according to claim 1, wherein: the magnetorheological sponge layer is adhered and filled in a gap between the inner hole wall of the outer ring framework and the outer surface of the inner ring.
3. The variable damping vibration attenuation device for industrial robot cutting machining according to claim 1, wherein: positioning bosses which are in contact with the high-speed bearing are arranged on the inner sides of the upper end cover and the lower end cover; the outer ring of the high-speed bearing is in interference fit with the inner ring, and the inner ring of the high-speed bearing is in interference fit with the sleeve; and a positioning shaft shoulder contacted with the inner ring of the high-speed bearing is arranged in the middle of the sleeve.
4. The variable damping vibration attenuation device for industrial robot cutting machining according to claim 1, wherein: after the variable damping vibration reduction device is connected with the industrial robot end effector spindle through the connecting support and the tool handle, the upper end face or the lower end face of the outer ring framework, the magnetorheological sponge layer and the inner ring are arranged on the same plane.
5. The variable damping vibration attenuation device for industrial robot cutting according to claim 4, wherein: the inner side of the connecting support is close to the connecting surface of the outer ring framework, a stop lever protrudes from the upper surface of the outer side of the upper end cover, and a round hole is formed in the stop lever to hook the stop lever, so that pulling force for preventing the high-speed bearing outer ring, the inner ring, the upper end cover and the lower end cover from following the rotation of the cutter handle is applied to the stop lever.
6. The variable damping vibration attenuation device for industrial robot cutting machining according to claim 1, wherein: the magnetorheological sponge layer is manufactured by impregnating the magnetorheological fluid into the polyurethane sponge for a preset time, and after the magnetorheological sponge layer is impregnated, the magnetorheological fluid is repeatedly extruded until the magnetorheological fluid is suspended in the air, so that the magnetorheological fluid is not overflowed and dripped.
7. A vibration damping method of a variable damping vibration damping device for industrial robot cutting, based on the variable damping device for industrial robot cutting according to any one of claims 1 to 6, characterized in that:
the vibration displacement, the speed, the acceleration and the cutting force of the tool nose point in the cutting process of the robot are monitored through the sensor, and the input current of the vibration damper is controlled by an external adjustable current source according to the vibration condition of the tool nose point, so that the damping force output of the vibration damper is changed.
8. The vibration damping method according to claim 7, characterized in that: judging the axial cutting force F of the current cutter Z With maximum tool radial cutting force F XY Axial vibration amplitude S of the knife point Z Radial vibration amplitude S with maximum knife point XY The relation conditions between the two include a condition A, and a corresponding processing flow A'; condition B corresponds to process flow B'.
9. The vibration damping method according to claim 8, characterized in that the condition a: axial cutting force F of tool during robot cutting Z Greater than the maximum tool radial cutting force F XY Exceeding a first preset value and at the moment, the axial vibration amplitude S of the tool nose point Z Radial vibration amplitude S greater than maximum point XY Beyond the second predetermined value, the process flow a' is performed:
according to the analysis of the balance condition of the tool nose point, the vibration damper needs to output the expected damping force F e From the formulaDetermining; judging the relation condition between the expected damping force and the range of the damping force which can be output by the vibration reduction device under the limit of the safety current, wherein the relation condition comprises a condition C and a corresponding processing flow C'; condition D, corresponds to process flow D'.
10. The vibration damping method according to claim 8, characterized in that the condition B: axial cutting force F of tool during robot cutting Z Less than or equal to the maximum cutter radial cutting force F XY Or axial vibration amplitude S of the tool nose point at the moment Z Radial vibration amplitude S of maximum point of tip XY Executing a processing flow B':
desired damping force F to be output by vibration damping device e From the formulaCalculation and determination, wherein L o Is the axial distance L between the end face of the outer ring shell and the tail end of the knife handle d Is the axial length of the magnetorheological sponge layer;
judging the relation condition between the expected damping force and the range of the damping force which can be output by the vibration reduction device under the limit of the safety current, wherein the relation condition comprises a condition C and a corresponding processing flow C'; condition D, corresponds to process flow D'.
11. The vibration damping method according to any one of claims 8 to 10, characterized in that condition C: expected damping force F of vibration damper during robot cutting e Within the range of the outputtable damping force, the process flow C' is performed:
adjusting the current input of an external adjustable current source to the vibration damper to enable the output damping force of the vibration damper to be equal to the expected damping force F e The same applies.
12. The vibration damping method according to any one of claims 8 to 10, characterized in that condition D: expected damping force F of vibration damper during robot cutting e In the range of the output damping forceIn addition, a process flow D' is performed:
the line diameter of the exciting coil, the polyurethane sponge density of the magnetorheological sponge layer and the magnetorheological fluid content in the vibration damper are adjusted to adjust the range of the output damping force;
or adjusting the current input of the external adjustable current source to the vibration damper to be a critical value of safety limit, so that the output damping force of the vibration damper reaches a limit value.
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