Lightweight robot arm with a foam aluminum composite skeleton

Abstract

This invention discloses a lightweight robotic arm with a foamed aluminum composite skeleton. The invention relates to the field of robotic arm technology. The lightweight robotic arm with a foamed aluminum composite skeleton includes a cast aluminum robot rotating base, a gradient foamed aluminum composite upper arm, a gradient foamed aluminum composite lower arm, and an end effector mounting base connected in sequence. The main bodies of the gradient foamed aluminum composite upper arm and the gradient foamed aluminum composite lower arm are both integrally formed foamed aluminum composite skeletons. Axial main truss rods and damping nodes are arranged axially inside the foamed aluminum composite skeleton. By setting the gradient foamed aluminum composite upper arm and the gradient foamed aluminum composite lower arm, and utilizing the porous characteristics of foamed aluminum, passive heat dissipation, vibration reduction, noise reduction, and health monitoring functions are integrated into the skeleton. Energy-free passive temperature control is achieved by filling the embedded axial cooling channels with phase change material, eliminating the need for an active cooling system.

Description

Technical Field

[0001] This invention relates to the field of robotic arm technology, and in particular to a lightweight robotic arm with a foamed aluminum composite skeleton. Background Technology

[0002] Lightweight robotic arms are mechanical devices that can move in space and perform tasks according to programmed instructions. They are the core execution components of industrial robots, service robots, and various special robots. Composed of components such as joints, movable arms, drivers, and end effectors, their essence is to replace or extend human operational capabilities, enabling high-efficiency, high-quality, and low-cost automated operations in dangerous, repetitive, precision, or high-intensity scenarios.

[0003] A search revealed a Chinese patent for a lightweight robotic arm and its manufacturing method, publication number CN114368007B. The arm includes an inner core and a carbon fiber layer sleeved on the outer surface of the inner core. A hollow carbon fiber tube runs through the inner core, and a power cable and / or communication cable are installed inside the hollow carbon fiber tube. The inner core is equipped with a connecting flange. The inner core is made of foam material.

[0004] The aforementioned device utilizes a composite technology that integrates lightweight carbon fiber to achieve a lightweight robotic arm with high strength, light weight, ultra-low energy consumption, high flexibility, and high precision. It employs a sandwich structure with an inner skeleton made of foamed PET and PPO beads, combined with a high-strength carbon fiber outer skin structure, achieving both lightweight and high strength. This reduces structural weight and addresses the fatigue strength issues associated with metal materials.

[0005] However, relying on optimizing carbon fiber layup and adding reinforcing ribs to achieve lightweight robotic arms still makes them prone to shell delamination and brittle fracture when the robotic arm moves at high speed and generates inertial impact or encounters accidental collisions. This affects the robot's operational accuracy and service life. At the same time, carbon fiber itself has a low damping coefficient and poor thermal conductivity, resulting in slow vibration decay of the robotic arm and seriously affecting the stability of end-effector positioning. In contrast, aluminum foam, as a lightweight porous metal material, has advantages such as high specific energy absorption, stable energy absorption process, sound insulation and vibration reduction, and has already been applied in the fields of collision protection in automobiles and rail transportation.

[0006] Therefore, the present invention provides a lightweight robotic arm with a foamed aluminum composite skeleton to solve the problems of high brittleness, poor impact resistance, and difficult heat dissipation of traditional pure carbon fiber robotic arms. Summary of the Invention

[0007] The purpose of this invention is to provide a lightweight robotic arm with a foamed aluminum composite skeleton to solve the problems mentioned in the background art above: To achieve the above objectives, the present invention provides the following technical solution: A lightweight robotic arm with a foamed aluminum composite skeleton includes a cast aluminum robot rotating base, a gradient foamed aluminum composite upper arm, a gradient foamed aluminum composite lower arm, and an end effector mounting base connected in sequence. The main bodies of the gradient foamed aluminum composite upper arm and the gradient foamed aluminum composite lower arm are both integrally formed foamed aluminum composite skeletons. The foamed aluminum composite skeleton has axial main truss rods and damping nodes arranged axially inside. The outer ring of the axial main truss rods is connected to several sets of radial honeycomb secondary truss rods, and damping nodes are provided at the truss intersection nodes. The foamed aluminum composite skeleton has prefabricated coaxially connected reducer mounting stepped cavity, motor mounting cavity one, and axially penetrating cable storage cavity. The inner walls of the reducer mounting stepped cavity, motor mounting cavity one, motor mounting cavity two, and cable storage cavity are fully covered with a buffer isolation layer. The foamed aluminum composite skeleton has several embedded axial cooling channels arranged inside and around the outer ring of the cable storage cavity. The foamed aluminum composite skeleton is covered with a high-strength composite shell. The gradient aluminum foam composite boom includes an aluminum foam transition section. Solid aluminum gradient reinforcement sections are provided at both the upper and lower ends of the aluminum foam transition section, and the solid aluminum gradient reinforcement sections and the aluminum foam transition section are integrally formed by metallurgical bonding. A boom harmonic reducer is installed inside the stepped cavity of the reducer installation. A boom composite shell covers the outer side of the aluminum foam transition section. A protective plate is attached to the side of the aluminum foam transition section away from the boom composite shell. Several countersunk pin holes are evenly distributed on both sides, penetrating the boom composite shell and the protective plate.

[0008] Preferably, the gradient aluminum foam composite forearm includes an aluminum foam transition section, and solid aluminum gradient reinforcement sections are provided at both the front and rear ends of the aluminum foam transition section. The outer side of the aluminum foam transition section is covered with a composite shell, and countersunk holes are provided on both the composite shell and the aluminum foam transition section. A drive motor is installed inside the motor mounting cavity through a flange connection plate.

[0009] By adopting the above technical solutions, the core architecture of the integrated foamed aluminum composite skeleton, with its non-traditional segmented casting bolt splicing structure, eliminates the risk of stress concentration at the splicing seams, thereby improving the overall torsional stiffness. The built-in truss and damping node collaborative structure evenly distributes concentrated stress throughout the entire skeleton, while simultaneously achieving active dissipation of vibration energy. Furthermore, the prefabricated installation cavity and cooling channels are integrally formed with the skeleton, eliminating the need for subsequent machining that could damage the load-bearing structure. The solid aluminum gradient reinforcement section design achieves a continuous transition between foamed aluminum and solid aluminum through metallurgical bonding, avoiding abrupt stress changes at the interface of different materials, and increasing local shear strength by more than 50%.

[0010] Preferably, a transmission cavity is provided on one side of the forearm aluminum foam transition section, and a synchronous wheel is rotatably installed inside the transmission cavity. A second motor mounting cavity is provided on the side of the forearm aluminum foam transition section away from the solid aluminum gradient reinforcement section of the forearm, and a second drive motor is installed inside the second motor mounting cavity. The aluminum foam composite skeleton is made of closed-cell aluminum foam with a density of 0.18-0.35 g / cm³ and a porosity of 70%-88%. The density is arranged in a gradient from the root of the upper arm to the middle of the forearm along the force direction of the arm, and the density of the aluminum foam in the force-concentrated part is higher than that in the non-force-concentrated part.

[0011] Preferably, a second forearm harmonic reducer is provided at the connection between the end effector mounting base and the forearm foam aluminum transition section. The drive shafts of the second drive motor and the second forearm harmonic reducer are respectively connected to two synchronous pulleys, and a synchronous belt is fitted around the outer ring of the synchronous pulley.

[0012] By adopting the above technical solution, using a prefabricated transmission cavity and a synchronous belt drive structure, and placing the drive motor at the rear, the center of gravity distribution of the aluminum foam transition section of the forearm is optimized, the end effector inertia is reduced, and the robot's dynamic response speed is improved. Synchronous belt drive has the advantages of smooth transmission, low noise, and no need for lubrication, making it suitable for the high-precision operation requirements of industrial robots. Furthermore, the transmission cavity is integrally formed with the frame, eliminating the need for additional transmission supports, reducing the number of parts, and ensuring the coaxiality of the transmission system.

[0013] Preferably, the axial main truss extends along the length of the upper arm foam aluminum transition section and the lower arm foam aluminum transition section, with a diameter of 5-7 mm, and is used to bear bending loads. The radial honeycomb secondary truss is arranged in a honeycomb pattern along the radial direction of the arm to bear torsional loads, and the axial secondary truss is arranged parallel to the axial main truss to help disperse axial loads.

[0014] Preferably, the embedded axial cooling channel is a parallel through-hole along the arm axis, with a diameter of 2-5 mm and a spacing of 8-12 mm. The embedded axial cooling channel is filled with a composite phase change energy storage material with a filling rate of 60%-75%.

[0015] By adopting the above technical solution, the axial main truss bears the main bending load, the radial honeycomb sub-truss bears the main torsional load, and the axial sub-truss assists in dispersing the axial load, forming a comprehensive stress bearing. In addition, the channel is filled with phase change energy storage material made of paraffin and graphene, which uses latent heat to absorb the heat generated by the drive components, eliminating the need for active heat dissipation systems such as fans and water cooling, thus avoiding the weight increase and failure points caused by heat dissipation systems.

[0016] Preferably, the buffer isolation layer is made of polyurethane foam with a thickness of 2-3 mm, and the buffer isolation layer is interference-fitted with the housing of drive motor one and drive motor two by 0.1-0.2 mm to isolate the high-frequency vibration of the drive components and absorb the impact energy of the collision.

[0017] By adopting the above technical solution and using an interference fit to tightly bond with the drive components, high-frequency vibrations generated during motor and reducer operation can be effectively isolated, preventing vibration from being transmitted to the arm frame and causing resonance. In the event of an accidental collision, the buffer isolation layer absorbs the remaining impact energy through its own compression deformation, preventing rigid collisions between the drive components and the inner wall of the frame.

[0018] Preferably, the opening ends of the stepped cavity for the reducer, the first motor mounting cavity, and the second drive motor are all embedded with metal nests. The metal nests are designed with gradient hardness, with the surface hardness in contact with the bearing housing being HB180-220 and the surface hardness in contact with the aluminum foam being HB80-120.

[0019] By adopting the above technical solution, the gradient hardness metal nesting design ensures the wear resistance and dimensional stability of the joint connection by the high hardness surface in contact with the bearing housing, and the low hardness surface combined with the foamed aluminum matches the elastic modulus of the foamed aluminum, effectively alleviating the interface stress concentration caused by the difference in thermal expansion coefficient.

[0020] Preferably, the upper arm composite shell and the lower arm composite shell are made of carbon fiber reinforced composite material with a thickness of 1.2 to 2.5 mm. The shell and the foam aluminum composite frame are bonded together with high temperature resistant structural adhesive with a bonding layer thickness of 0.1 to 0.2 mm, and countersunk pins are provided at intervals for fixation with a countersunk pin spacing of 60 to 90 mm.

[0021] Preferably, the skeleton surfaces of both the gradient aluminum foam composite upper arm and the gradient aluminum foam composite lower arm are prefabricated with axial sensor embedded grooves, and distributed fiber optic strain sensors are continuously arranged in the axial sensor embedded grooves.

[0022] By adopting the above technical solution, a composite connection method using structural adhesive bonding and countersunk pin reinforcement is used, which not only ensures the integrity and sealing of the connection, but also avoids the defect of easy delamination under long-term vibration of pure adhesive bonding. While ensuring the connection strength, the damage to the shell structure is minimized. The stress distribution of the entire arm body can be monitored in real time through distributed fiber optic strain sensors, and the location and degree of fatigue damage can be accurately identified.

[0023] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention, by setting up a gradient aluminum foam composite upper arm and a gradient aluminum foam composite lower arm, the lightweight arm adopts a three-layer gradient composite skeleton consisting of a directional duct core layer, a metal truss layer, and a gradient transition layer. Utilizing the inherent characteristics of aluminum foam—lightweight, porous, high specific strength, and capable of gradient molding—and through a density gradient arrangement along the force direction of the arm, the overall weight is reduced by 35%–40%, while the specific bending strength is increased by 40% and the specific torsional stiffness is increased by 45%. This solves the defects of carbon fiber sandwich structures, such as easy sagging and poor shear resistance.

[0024] 2. This invention integrates passive heat dissipation, vibration reduction and noise reduction, and health monitoring functions into the frame by setting up a cable storage cavity, an embedded axial cooling channel, an upper arm foam aluminum transition section, and a lower arm foam aluminum transition section, and by utilizing the porous characteristics of foam aluminum: energy-free passive temperature control is achieved by filling the embedded axial cooling channel with phase change material, without the need to install an active heat dissipation system.

[0025] 3. This invention, by setting up an axial main truss, damping nodes, and a transition section of the main truss in conjunction with the aluminum foam transition section of the upper arm and the lower arm, utilizes the high damping characteristics of aluminum foam itself. Combined with the damping node structure at the nodes of the axial main truss and the axial secondary truss, it can effectively absorb the vibration and impact generated by high-speed movement, thereby improving the robot's positioning accuracy and operational stability. Furthermore, the cable storage cavity and axial sensor pre-embedded groove are directly prefabricated during the molding of the aluminum foam skeleton, eliminating the need for subsequent mechanical processing that could damage the load-bearing structure. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of a lightweight robotic arm with a foamed aluminum composite skeleton according to the present invention. Figure 2 This is a schematic diagram of the structure of the reducer mounting stepped cavity, motor mounting cavity 1, forearm foam aluminum transition section, and upper arm foam aluminum transition section in a lightweight robot arm with a foam aluminum composite skeleton according to the present invention. Figure 3 This invention relates to a lightweight robotic arm with a foamed aluminum composite skeleton. Figure 2 Enlarged view of area A; Figure 4 This is a structural schematic diagram of the countersunk pin holes, the upper arm composite shell, and the protective plate in a lightweight robot arm with a foamed aluminum composite frame according to the present invention. Figure 5 This is a schematic diagram of the axial main truss, the forearm foam aluminum transition section, the axial sensor pre-embedded groove, and the metal nesting structure of a lightweight robot arm with a foam aluminum composite skeleton according to the present invention. Figure 6 This is a structural schematic diagram of the radial honeycomb sub-truss, axial main truss, and damping nodes in a lightweight robot arm with a foamed aluminum composite skeleton according to the present invention. Figure 7 This is a schematic diagram of the transmission cavity, synchronous belt, and synchronous pulley in a lightweight robotic arm with a foamed aluminum composite skeleton according to the present invention. Figure 8 This is a structural schematic diagram of the axial sub-truss, cable storage cavity, motor mounting cavity 2, and drive motor 2 of a lightweight robot arm with a foamed aluminum composite skeleton according to the present invention.

[0027] Explanation of the labels in the diagram: 1. Cast aluminum robot rotating base; 2. Gradient foamed aluminum composite upper arm; 201. Foamed aluminum transition section of the upper arm; 202. Solid aluminum gradient reinforcement section; 203. Reducer mounting stepped cavity; 204. Upper arm harmonic reducer one; 205. Countersunk pin hole; 206. Upper arm composite shell; 207. Protective plate; 3. Gradient foamed aluminum composite lower arm; 301. Foamed aluminum transition section of the lower arm; 302. Solid aluminum gradient reinforcement section of the lower arm; 303. Motor mounting cavity one; 304. Flange connection plate; 305. Metal nest; 306. Buffer isolation. Layer; 307, Drive Motor 1; 308, Forearm Countersunk Hole; 309, Axial Sensor Embedded Slot; 3010, Forearm Composite Housing; 3011, Motor Mounting Cavity 2; 3012, Transmission Cavity; 3013, Synchronous Belt; 3014, Synchronous Pulley; 3015, Forearm Harmonic Reducer 2; 3016, Drive Motor 2; 401, Axial Main Truss Rod; 402, Radial Honeycomb Sub-truss Rod; 403, Damping Node; 404, Axial Sub-truss Rod; 405, Cable Reception Cavity; 406, Embedded Axial Cooling Channel; 5, End Actuator Mounting Base. Detailed Implementation

[0028] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0029] like Figures 1-8 As shown, a lightweight robot arm with a foamed aluminum composite frame includes a cast aluminum robot rotating base 1, a gradient foamed aluminum composite upper arm 2, a gradient foamed aluminum composite lower arm 3 and an end effector mounting base 5 connected in sequence. The main bodies of the gradient foamed aluminum composite upper arm 2 and the gradient foamed aluminum composite lower arm 3 are both integrally formed foamed aluminum composite frames. The foamed aluminum composite frame has axial main truss rods 401 and damping nodes 403 arranged axially inside. The outer ring of the axial main truss rods 401 is connected to several sets of radial honeycomb secondary truss rods 402, and damping nodes 403 are provided at the truss intersection nodes. The foamed aluminum composite frame has prefabricated coaxially connected reducer mounting stepped cavity 203, motor mounting cavity one 303 and axially penetrating cable storage cavity 405. The inner walls of the reducer mounting stepped cavity 203, motor mounting cavity one 303, motor mounting cavity two 3011 and cable storage cavity 405 are fully covered with a buffer isolation layer 306. The foamed aluminum composite frame has several embedded axial cooling channels 406 arranged inside and around the outer ring of the cable storage cavity 405. The foamed aluminum composite frame is covered with a high-strength composite shell. The gradient aluminum foam composite boom 2 includes a boom aluminum foam transition section 201. The upper and lower ends of the boom aluminum foam transition section 201 are provided with solid aluminum gradient reinforcement sections 202. The solid aluminum gradient reinforcement sections 202 and the boom aluminum foam transition section 201 are integrally formed by metallurgical bonding. The boom harmonic reducer 204 is installed inside the reducer mounting stepped cavity 203. The outer side of the boom aluminum foam transition section 201 is covered with a boom composite shell 206. A protective plate 207 is attached to the side of the boom aluminum foam transition section 201 away from the boom composite shell 206. Several countersunk pin holes 205 are evenly opened on both sides of the boom composite shell 206 and the protective plate 207.

[0030] As a technical optimization of the present invention, the gradient aluminum foam composite forearm 3 includes an aluminum foam transition section 301. The front and rear ends of the aluminum foam transition section 301 are provided with solid aluminum gradient reinforcing sections 302. The outer side of the aluminum foam transition section 301 is covered with a composite shell 3010. The composite shell 3010 and the aluminum foam transition section 301 are both provided with countersunk holes 308. The drive motor 307 is installed inside the 303 through a flange connecting plate 304.

[0031] The core architecture of the integrated foamed aluminum composite frame, unlike the traditional segmented casting and bolt-jointed structure, eliminates the risk of stress concentration at the joints, thus improving the overall torsional stiffness. The built-in truss and damping nodes (403) work together to evenly distribute concentrated stress throughout the frame, while actively dissipating vibration energy. Furthermore, the prefabricated installation cavity and cooling channels are integrally formed with the frame, eliminating the need for subsequent machining that could damage the load-bearing structure. The solid aluminum gradient reinforcement section design achieves a continuous transition between foamed aluminum and solid aluminum through metallurgical bonding, avoiding abrupt stress changes at the interface of different materials and increasing local shear strength by over 50%.

[0032] As a technical optimization of the present invention, a transmission cavity 3012 is provided on one side of the forearm foam aluminum transition section 301 at a forward position. A synchronous wheel 3014 is rotatably installed inside the transmission cavity 3012. A motor mounting cavity 3011 is provided on the side of the forearm foam aluminum transition section 301 away from the solid aluminum gradient reinforcement section 302 of the forearm. A drive motor 3016 is installed inside the motor mounting cavity 3011. The foam aluminum composite skeleton is made of closed-cell foam aluminum with a density of 0.18 to 0.35 g / cm³ and a porosity of 70% to 88%. The density is arranged in a gradient from the middle of the upper arm to the root of the forearm along the force direction of the arm. The density of the foam aluminum in the force-concentrated part is higher than that in the non-force-concentrated part.

[0033] As a technical optimization of the present invention, a second harmonic reducer 3015 is provided at the connection between the end effector mounting base 5 and the forearm foam aluminum transition section 301. The drive shafts of the second drive motor 3016 and the second forearm harmonic reducer 3015 are respectively connected to two synchronous pulleys 3014. The outer ring of the synchronous pulley 3014 is fitted with a synchronous belt 3013.

[0034] The synchronous belt 3013 transmission structure, employing a prefabricated transmission cavity 3012, places the drive motor at the rear, optimizing the center of gravity distribution of the aluminum foam transition section 301 of the forearm, reducing end effector inertia, and improving the robot's dynamic response speed. The synchronous belt 3013 transmission offers advantages such as smooth transmission, low noise, and no lubrication required, making it suitable for the high-precision operation requirements of industrial robots. Furthermore, the transmission cavity 3012 is integrally molded with the frame, eliminating the need for additional transmission supports, reducing the number of parts, and ensuring the coaxiality of the transmission system.

[0035] As a technical optimization of the present invention, the axial main truss 401 extends along the length direction of the upper arm aluminum foam transition section 201 and the lower arm aluminum foam transition section 301, with a diameter of 5-7mm, and is used to bear bending loads. The radial honeycomb sub-truss 402 is arranged in a honeycomb pattern along the radial direction of the arm to bear torsional loads, and the axial sub-truss 404 is arranged parallel to the axial main truss 401 to help disperse axial loads.

[0036] As a technical optimization of the present invention, the embedded axial cooling channel 406 is a parallel through-hole along the arm axis, with a channel diameter of 2 to 5 mm and a channel spacing of 8 to 12 mm. The embedded axial cooling channel 406 is filled with a composite phase change energy storage material with a filling rate of 60% to 75%.

[0037] The axial main truss 401 bears the main bending load, the radial honeycomb sub-truss 402 bears the main torsional load, and the axial sub-truss 404 assists in dispersing the axial load, forming an all-round stress bearing. In addition, the channel is filled with phase change energy storage material made of paraffin and graphene, which uses latent heat to absorb the heat generated by the drive components, eliminating the need for active heat dissipation systems such as fans and water cooling, thus avoiding the weight increase and failure points caused by heat dissipation systems.

[0038] As a technical optimization of the present invention, the buffer isolation layer 306 is made of polyurethane foam with a thickness of 2-3 mm, and the buffer isolation layer 306 is interference-fitted with the housing of drive motor 1 307 and drive motor 2 3016 by 0.1-0.2 mm, which is used to isolate the high-frequency vibration of the drive components and absorb the impact energy of the collision.

[0039] The interference fit design ensures a tight seal with the drive components, effectively isolating high-frequency vibrations generated during motor and reducer operation and preventing vibration transmission to the boom frame, which could cause resonance. In the event of an accidental collision, the buffer isolation layer 306 absorbs the remaining impact energy through its own compression deformation, preventing a rigid collision between the drive components and the inner wall of the frame.

[0040] As a technical optimization of the present invention, metal nests 305 are embedded in the opening ends of the reducer mounting stepped cavity 203, the motor mounting cavity 303, and the drive motor 3016. The metal nests 305 adopt a gradient hardness design, with the surface hardness in contact with the bearing seat being HB180~220 and the surface hardness in combination with the foamed aluminum being HB80~120.

[0041] The high-hardness surface of the graded hardness metal nested with 305 in contact with the bearing housing ensures the wear resistance and dimensional stability of the joint connection, while the low-hardness surface combined with the foamed aluminum matches the elastic modulus of the foamed aluminum, effectively alleviating the interface stress concentration caused by the difference in thermal expansion coefficient.

[0042] As a technical optimization of the present invention, the upper arm composite shell 206 and the lower arm composite shell 3010 are made of carbon fiber reinforced composite material with a thickness of 1.2 to 2.5 mm. The shell and the foam aluminum composite frame are bonded together with high temperature resistant structural adhesive with a bonding layer thickness of 0.1 to 0.2 mm, and countersunk pins are provided at intervals for fixation with a countersunk pin spacing of 60 to 90 mm.

[0043] As a technical optimization of the present invention, the skeleton surfaces of the gradient aluminum foam composite upper arm 2 and the gradient aluminum foam composite lower arm 3 are prefabricated with axial sensor embedded grooves 309, and distributed fiber optic strain sensors are continuously arranged in the axial sensor embedded grooves 309.

[0044] The composite connection method, which combines bonding and countersunk pin reinforcement, ensures both the integrity and sealing of the connection, while avoiding the defects of pure bonding that are prone to delamination under long-term vibration. It minimizes damage to the outer shell structure while ensuring connection strength. The distributed fiber optic strain sensor can monitor the stress distribution along the entire length of the arm in real time, accurately identifying the location and extent of fatigue damage.

[0045] It should be noted that this invention is a lightweight robotic arm with a foamed aluminum composite skeleton. In use, when the robotic arm is running at high speed, the load force and torque generated by the end effector are transmitted to the end of the foamed aluminum transition section 301 of the forearm through the end effector mounting base 5, and then continuously transmitted to the base along the skeleton axis. During the process, the bending stress and torsional stress generated by the load are first borne by the axial main truss rod 401 and the axial secondary truss rod 404. At this time, the radial honeycomb secondary truss rod 402 mainly bears the torsional load, which evenly distributes the concentrated stress to the entire foamed aluminum skeleton and avoids deformation caused by local stress concentration.

[0046] When the forearm foam aluminum transition section 301 and the upper arm foam aluminum transition section 201 vibrate, the vibration wave is transmitted to the truss node. The silicone rubber damping of the damping node 403 set at the node undergoes shear deformation, converting the mechanical energy of the vibration into heat energy for dissipation. Furthermore, the slots of the drive motor 2 3016, drive motor 1 307, upper arm harmonic reducer 1 204, and forearm harmonic reducer 2 3015 are all equipped with buffer isolation layers 306. At this time, the high-frequency vibration generated during operation is first absorbed by the buffer isolation layer 306 on the inner wall of the mounting cavity, so as to effectively isolate the vibration of the drive component from being transmitted to the arm frame, and at the same time play a role in noise reduction.

[0047] When the robotic arm encounters an accidental collision, the outermost composite shell 206 of the upper arm and the composite shell 3010 of the lower arm first bear the impact. The high toughness of these shells absorbs some of the impact energy, preventing brittle fracture. When the impact load is transferred to the closed-cell aluminum foam transition layer of the gradient aluminum foam composite upper arm 2 and gradient aluminum foam composite lower arm 3, the pore walls of the aluminum foam undergo progressive plastic collapse, smoothly absorbing a large amount of impact energy. The specific energy absorption of aluminum foam can reach 15 kJ / kg, more than three times that of aluminum alloy, and the energy absorption process is without rebound, preventing secondary damage to the arm body. In the event of secondary damage, when the impact load exceeds the bearing capacity of the aluminum foam, the metal reinforced truss acts as a second line of defense. Through the plastic deformation of the truss members, it continues to absorb energy, preventing the overall fracture of the frame and ensuring the basic structural integrity of the boom. Furthermore, when impacted, because both drive motor 1 (307) and drive motor 2 (3016) are equipped with buffer isolation layers (306), these layers can still absorb the remaining impact energy through their own compression deformation, reducing the probability of rigid collision damage between drive motor 1 (307) and drive motor 2 (3016) and the inner wall of the frame.

[0048] Meanwhile, both the upper arm foam aluminum transition section 201 and the lower arm foam aluminum transition section 301 have embedded axial cooling channels 406. Personnel can fill these channels with heat-absorbing materials, such as paraffin and graphene composite phase change energy storage materials, with a filling rate of 70% and a 30% space reserved for the thermal expansion of the phase change material. When the motor and reducer generate heat during operation, the heat is first transferred to the foam aluminum skeleton through the inner wall of the mounting cavity, and then conducted to the phase change material in the cooling channel to improve the heat dissipation effect. This solves the problem of heat dissipation difficulties in the closed shell of traditional carbon fiber arms. When heated, the paraffin changes from solid to liquid, absorbing a large amount of latent heat and storing it. When the robot stops or the load decreases, the phase change material changes from liquid to solid, slowly releasing the stored heat into the environment through the foam aluminum skeleton.

[0049] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A lightweight robotic arm with a foamed aluminum composite skeleton, comprising a cast aluminum robotic rotating base (1), a gradient foamed aluminum composite upper arm (2), a gradient foamed aluminum composite lower arm (3), and an end effector mounting base (5) connected in sequence, characterized in that: The main body of the gradient aluminum foam composite upper arm (2) and the gradient aluminum foam composite lower arm (3) are both integrally formed aluminum foam composite skeletons. The foamed aluminum composite skeleton is internally arranged with axial main truss rods (401) and damping nodes (403) along the axial direction. The outer ring of the axial main truss rods (401) is connected with several sets of radial honeycomb secondary truss rods (402), and damping nodes (403) are provided at the truss intersection nodes. The foamed aluminum composite skeleton is internally prefabricated with a coaxially connected reducer mounting stepped cavity (203), a motor mounting cavity one (303), and an axially penetrating cable storage cavity (405). The inner side of the motor mounting cavity one (303) is provided with a metal nest (305). The inner walls of the reducer mounting stepped cavity (203), the metal nest (305), the motor mounting cavity two (3011), and the cable storage cavity (405) are fully covered with a buffer isolation layer (306). The foamed aluminum composite skeleton is internally arranged with several embedded axial cooling channels (406) around the outer ring of the cable storage cavity (405). The gradient aluminum foam composite boom (2) includes a boom aluminum foam transition section (201). The upper and lower ends of the boom aluminum foam transition section (201) are provided with solid aluminum gradient reinforcement sections (202). The solid aluminum gradient reinforcement sections (202) and the boom aluminum foam transition section (201) are integrally formed by metallurgical bonding. The boom harmonic reducer (204) is installed inside the reducer mounting stepped cavity (203). The outer side of the boom aluminum foam transition section (201) is covered with a boom composite shell (206). A protective plate (207) is pasted on the side of the boom aluminum foam transition section (201) away from the boom composite shell (206). Several countersunk pin holes (205) are evenly opened on both sides of the boom composite shell (206) and the protective plate (207).

2. The lightweight robotic arm with a foamed aluminum composite skeleton according to claim 1, characterized in that: The gradient aluminum foam composite forearm (3) includes an aluminum foam transition section (301) forearm. The front and rear ends of the aluminum foam transition section (301) are provided with solid aluminum gradient reinforcement sections (302) forearm. The outer side of the aluminum foam transition section (301) forearm is covered with a composite shell (3010) forearm. The composite shell (3010) forearm and the aluminum foam transition section (301) forearm are both provided with countersunk holes (308) forearm. The motor mounting cavity (303) is equipped with a drive motor (307) through a flange connecting plate (304).

3. The lightweight robotic arm with a foamed aluminum composite skeleton according to claim 2, characterized in that: A transmission cavity (3012) is provided on one side of the forearm foam aluminum transition section (301) at the front position. A synchronous wheel (3014) is rotatably installed inside the transmission cavity (3012). A motor mounting cavity two (3011) is provided on the side of the forearm foam aluminum transition section (301) away from the solid aluminum gradient reinforcement section (302) of the forearm. A drive motor two (3016) is installed inside the motor mounting cavity two (3011). The foam aluminum composite skeleton is made of closed-cell foam aluminum, and the foam aluminum composite skeleton is arranged with a density gradient along the force direction of the arm. The foam aluminum density in the force-concentrated part is higher than that in the non-force-concentrated part.

4. The lightweight robotic arm with a foamed aluminum composite skeleton according to claim 3, characterized in that: A second harmonic reducer (3015) for the forearm is provided at the connection between the end effector mounting base (5) and the forearm foam aluminum transition section (301). The drive shafts of the second drive motor (3016) and the second forearm harmonic reducer (3015) are respectively connected to two synchronous pulleys (3014). The outer ring of the synchronous pulley (3014) is fitted with a synchronous belt (3013).

5. The lightweight robotic arm with a foamed aluminum composite skeleton according to claim 1, characterized in that: The axial main truss (401) extends along the length of the upper arm aluminum foam transition section (201) and the lower arm aluminum foam transition section (301) to bear bending loads. The radial honeycomb sub-truss (402) is arranged in a honeycomb pattern along the radial direction of the arm to bear torsional loads. The axial sub-truss (404) is arranged parallel to the axial main truss (401) to help disperse axial loads.

6. The lightweight robotic arm with a foamed aluminum composite skeleton according to claim 1, characterized in that: The embedded axial cooling channel (406) is a parallel through-hole along the arm axis, with a diameter of 2-5 mm and a spacing of 8-12 mm. The embedded axial cooling channel (406) is filled with a composite phase change energy storage material.

7. The lightweight robotic arm with a foamed aluminum composite skeleton according to claim 3, characterized in that: The buffer isolation layer (306) is made of polyurethane foam with a thickness of 2-3 mm. The buffer isolation layer (306) is interference-fitted with the housing of drive motor one (307) and drive motor two (3016) by 0.1-0.2 mm. It is used to isolate the high-frequency vibration of the drive components and absorb the impact energy of the collision.

8. The lightweight robotic arm with a foamed aluminum composite skeleton according to claim 3, characterized in that: The opening ends of the stepped cavity (203) for the reducer, the first cavity (303) for the motor, and the second drive motor (3016) are all embedded with metal nests (305), and the metal nests (305) are designed with gradient hardness.

9. The lightweight robotic arm with a foamed aluminum composite skeleton according to claim 1, characterized in that: The boom composite shell (206) and the forearm composite shell (3010) are made of carbon fiber reinforced composite material. The boom composite shell (206) and the forearm composite shell (3010) are bonded to the aluminum foam composite frame by high temperature resistant structural adhesive and are fixed by countersunk pins at intervals.

10. A lightweight robotic arm with a foamed aluminum composite skeleton according to claim 4, characterized in that: The skeleton surfaces of the gradient aluminum foam composite upper arm (2) and the gradient aluminum foam composite lower arm (3) are prefabricated with axial sensor embedded grooves (309), and distributed fiber optic strain sensors are continuously arranged in the axial sensor embedded grooves (309).

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