Aircraft skin tool based on compliant mechanism

Abstract

The invention discloses an aircraft skin tool based on a compliant mechanism. The aircraft skin tool comprises a tool framework, a constant-force clamping assembly, a bistable high-precision positioning assembly, a skin positioning check block, a linear motor and an electric cylinder sliding table. The tool framework is formed by welding two stand columns and five cross beams, and threaded holes are distributed in each stand column and each cross beam and used for installing assemblies. The linear motor and the electric cylinder sliding table are installed on cross beams and stand columns on the four sides of the tool framework respectively. The constant force clamping assembly is installed on a linear motor or an electric cylinder sliding table through an auxiliary clamping sliding block so as to clamp the skin. The skin positioning stop block is mounted on the auxiliary clamping slide block; the bistable high-precision positioning assembly is installed on three cross beams in the middle of the tool framework through lugs with threaded holes at the bottom of the flexible bistable mechanism so as to position the skin. The flexible clamping device has the advantages of constant-force clamping, high-precision positioning and reconfigurable clamping, and is suitable for flexible clamping during machining of skins of various specifications.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of tooling equipment, and particularly relates to an aircraft skin tooling based on a compliant mechanism and a method for assembling the aircraft skin tooling based on the compliant mechanism. BACKGROUND

[0002] The aircraft skin refers to a shape member that is wrapped outside the aircraft framework structure and is fixed to the framework by an adhesive or rivets to form the aerodynamic shape of the aircraft. The aircraft skin has small rigidity and light weight, and especially the large-size skin is prone to deformation during hole making, assembly and other processing, thereby affecting the aerodynamic performance of the sheet part. In order to ensure the stability of the aircraft skin processing and manufacturing process, most toolings are designed to be rigid structures, and the processing of one aircraft skin corresponds to one rigid jig; this mode leads to problems such as long design cycle, long manufacturing cycle, large development cost and serious resource waste of the aircraft skin tooling.

[0003] On the one hand, the traditional aircraft skin tooling is mostly rigid structure, and the skin is clamped and positioned by the clamping plate and rubber rope on the jig. For a variety of different sizes of skin, a large number of toolings respectively adapted to various processing scenarios need to be manufactured, which is time-consuming and laborious and also wastes a large amount of labor and equipment costs and occupies a large amount of factory space. On the other hand, the traditional tooling clamps the skin by the rubber rope, and the clamping force reliability is low, and the problem of unstable clamping force leading to deformation of the skin exists.

[0004] With the development of aircraft processing and manufacturing technology, the tooling structure gradually develops into a flexible tooling of "one to many", and higher requirements are also put forward for the processing and manufacturing process of the aircraft skin, so it is particularly necessary to develop a flexible tooling suitable for various specifications of aircraft skin, which has constant clamping force, stable positioning and reconfigurability. SUMMARY

[0005] In view of the above problems, the present application provides an aircraft skin tooling based on a compliant mechanism, which uses a compliant bistable mechanism and a compliant constant force mechanism to provide reliable positioning and constant clamping force, and the design of each execution end can be detached and replaced, thereby improving the flexibility of the tooling to adapt to different work scenarios.

[0006] The first technical solution adopted by the present application is an aircraft skin tooling based on a compliant mechanism, comprising: a tooling framework, the tooling framework is welded by two longitudinal columns and five cross beams, each column and cross beam is distributed with threaded holes for installing components, and the bottom is a supporting leg; a linear motor and an electric cylinder sliding table, the linear motor is installed on the upper and lower cross beams of the tooling framework, and the electric cylinder sliding table is installed on the two side columns of the tooling framework; a constant force clamping assembly, the constant force clamping assembly is installed on the linear motor or the electric cylinder sliding table by an auxiliary clamping sliding block to clamp the skin; The bistable positioning assembly is installed on the middle three beams of the tool skeleton through the threaded hole ears at the bottom of the compliant bistable mechanism to position the skin; The skin positioning block is installed on the auxiliary clamping sliding block.

[0007] The present application is also characterized in that, Preferably, the constant force clamping assembly includes an auxiliary clamping sliding block, a compliant constant force mechanism, a clamping actuator, a micro electric push cylinder, a driving clamping electric cylinder sliding table, an auxiliary sliding rail-sliding block, and an auxiliary connecting sliding block. The clamping actuator is divided into an upper clamping actuator and a lower clamping actuator, and is connected to the auxiliary clamping sliding block and the guide beam of the compliant constant force mechanism, respectively, through a double-hole bolt quick-change mode. The micro electric push cylinder is fixed to the compliant constant force mechanism frame and connected to the preloading block of the compliant constant force mechanism to pre-load the compliant constant force mechanism. The driving clamping electric cylinder sliding table is installed on the auxiliary clamping sliding block. The bottom of the compliant constant force mechanism frame is connected to the sliding block of the driving clamping electric cylinder sliding table. The auxiliary sliding rail-sliding block is installed on the auxiliary clamping sliding block in parallel to the driving clamping electric cylinder sliding table. The auxiliary connecting sliding block is used to connect the compliant constant force mechanism frame and the auxiliary sliding rail-sliding block.

[0008] Preferably, the compliant constant force mechanism includes a compliant constant force mechanism frame, a negative stiffness beam, a positive stiffness beam, a preloading block, and a constant force guide beam. The top of both sides of the compliant constant force mechanism frame has a hole for connecting with the auxiliary connecting sliding block, which is used to connect the compliant constant force mechanism with the auxiliary sliding rail-sliding block. The bottom of the compliant constant force mechanism frame is provided with a hole for the micro electric push cylinder to pass through, and the micro electric push cylinder is threadedly connected to the bottom of the compliant constant force mechanism frame. The positive stiffness beam is in the shape of a U, and the two horizontal sections are connected to the constant force guide beam and the preloading block, respectively. The preloading block is located inside the compliant constant force mechanism frame and directly below the constant force guide beam. The negative stiffness beam is designed in a series arrangement of two groups of beams, and each group is two parallel beams. One end of each negative stiffness beam is connected to the inner surface of the compliant constant force mechanism frame, and the other end is connected to the guide beam. The preloading block has a threaded hole for connecting the end of the micro electric push cylinder. The constant force guide beam has a hole for connecting with the clamping actuator. The principle of the compliant constant force mechanism outputting constant force is that the sum of the stiffness of the designed positive stiffness beam and negative stiffness beam is 0 under a certain input displacement.

[0009] Preferably, the clamping actuator is divided into an upper clamping actuator and a lower clamping actuator. The output end of the clamping actuator is a rubber ball head. The bottom of the lower clamping actuator is a U-shaped groove structure, and the groove wall has a hole for connecting with the constant force guide beam. The bottom of the upper clamping actuator has a protrusion, and the protrusion has a hole for connecting with the auxiliary clamping sliding block.

[0010] Preferably, the bistable positioning assembly comprises a compliant bistable mechanism, a positioning actuator, a universal swing vacuum chuck with a positioning ball head, and a vacuum pressure sensor; the compliant bistable mechanism is installed on the middle three beams of the tool skeleton through the threaded lugs at the bottom; the positioning actuator is installed on the guide beam of the compliant bistable mechanism through the double-hole plug-in quick-change mode; the universal swing vacuum chuck with a positioning ball head is threadedly connected to the end of the positioning actuator; and the vacuum pressure sensor is installed on the universal swing vacuum chuck with a positioning ball head.

[0011] Preferably, the compliant bistable mechanism comprises a compliant bistable mechanism frame, bistable beams, and stable guide beams; the compliant bistable mechanism frame has threaded lugs at the bottom for installation on the middle three beams of the tool skeleton; the bistable beams are designed in a parallel arrangement of two groups of beams, each group of beams is composed of two bistable beams connected in series, one end of each bistable beam is connected to the frame of the compliant bistable mechanism, and the other end is connected to the stable guide beam; the stable guide beam has holes for connecting the positioning actuator; and the principle of the compliant bistable mechanism is that the mechanism can maintain two stable forms, and a certain energy barrier needs to be overcome each time the form is changed, and when the input energy cannot overcome the designed energy barrier, the compliant bistable mechanism can maintain the current stable form unchanged.

[0012] Preferably, the positioning actuator has a U-shaped slot structure at the bottom, and the slot wall has holes for connecting the compliant bistable mechanism; and the positioning actuator has a threaded hole at the top for connecting the universal swing vacuum chuck with a positioning ball head.

[0013] Preferably, the skin positioning block is L-shaped and is installed on the auxiliary clamping slider.

[0014] The second technical solution adopted by the present application is an assembly method of an aircraft skin tool based on a compliant mechanism, and the specific operation steps are as follows: a skin positioning block is installed on each auxiliary clamping slider on the lowermost beam of the tool skeleton to limit the movement freedom in the z direction and the rotation freedom in the x direction of the skin; a skin positioning block is installed on the auxiliary clamping slider of the tool skeleton column to limit the movement freedom in the y direction of the skin; the universal swing vacuum chuck with a positioning ball head is used to adsorb the surface of the skin to further position the skin; and the constant force clamping assembly is used to further clamp the skin.

[0015] The present application has the following advantages: (1) The compliant constant force mechanism can be pre-tightened using a micro electric cylinder within a certain range, the size and direction of the pre-tightening displacement can be changed to change the size of the output constant force, and under a certain input displacement, the compliant constant force mechanism does not need to rely on sensor feedback or complex control algorithms, but only relies on its own mechanical structure to maintain a constant output force, and uses the clamping actuator to clamp the skin, thereby simplifying the structure of the clamp; (2) The compliant constant force mechanism can automatically adjust the layout of the bistable positioning components through the slide, and / or can quickly replace the clamping actuators of different sizes through the quick change method of the double-hole pin to adapt to the processing of skins of different sizes and types, thereby reducing the reconstruction time.

[0016] (3) The compliant constant force mechanism can be pre-tightened by a micro electric push cylinder, thereby adjusting the equilibrium point where the total stiffness after the superposition of the positive and negative stiffness beams is zero, thereby achieving a change in the constant force output value.

[0017] (4) The compliant bistable mechanism can maintain the current stable state within a certain force range, that is, maintain the stable state of the positioning point without the need for additional sensors and controllers; (5) Skin positioning, using " N -2-1" positioning principle, composed of multiple flexible bistable mechanisms" N " positioning points; the installation position of the bistable positioning component can be changed by the ear piece with threaded holes at the bottom of the flexible bistable mechanism, that is, the layout of the positioning points can be changed, or / and the end effectors of different specifications can be quickly replaced by the quick-change method of the double-hole pin to adapt to the processing of skins of different sizes and types, thereby improving the flexibility of the tooling. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the structure of an aircraft skin tooling based on a compliant mechanism provided by the present invention; Figure 2 for Figure 1 A magnified view of part A in FIG; Figure 3 A diagram of the constant force clamping assembly provided by the present invention; Figure 4 A schematic diagram of the structure of the compliant constant force mechanism provided by the present invention; Figure 5 A diagram of the bistable positioning assembly and a cross-sectional view of the universal swing vacuum suction cup with a positioning ball head provided by the present invention; Figure 6 A schematic diagram of the structure of the compliant bistable mechanism provided by the present invention; Figure 7 A schematic diagram of the positioning block structure provided by the present invention; Figure 8 Schematic diagram of the structure of the aircraft skin fixture clamping the skin based on the flexible mechanism provided by the present invention Figure 1 ; Figure 9 Schematic diagram of the structure of the aircraft skin fixture clamping the skin based on the flexible mechanism provided by the present invention Figure 2 .

[0019] Wherein, 1 - tool skeleton; 2 - linear motor; 3 - electric cylinder sliding table; 4 - constant force clamping assembly; 5 - bistable positioning assembly; 6 - skin positioning stopper; 7 - supporting leg; 8 - auxiliary clamping sliding block; 9 - compliant constant force mechanism; 91 - compliant constant force mechanism frame; 92 - negative stiffness beam; 93 - positive stiffness beam; 94 - preloading block; 95 - constant force guide beam; 10 - clamping actuator; 101 - upper clamping actuator; 102 - lower clamping actuator; 11 - micro electric push cylinder; 12 - driving clamping electric cylinder sliding table; 13 - auxiliary sliding rail - sliding block; 14 - auxiliary connecting sliding block; 15 - compliant bistable mechanism; 151 - compliant bistable mechanism frame; 152 - bistable beam; 153 - stable guide beam; 16 - positioning actuator; 17 - universal swing vacuum chuck with positioning ball head; 18 - vacuum pressure sensor; 19 - skin. DETAILED DESCRIPTION

[0020] The application will be described in detail below with reference to the drawings and specific embodiments.

[0021] Embodiment 1 Referring to the drawings Figures 1 to 9 The embodiment of the application discloses an aircraft skin tool based on a compliant mechanism, comprising: A tool skeleton 1, which is welded by two longitudinal columns and five cross beams, and each column and cross beam is provided with threaded holes for installing components, and the bottom is a supporting leg 7; A linear motor 2 and an electric cylinder sliding table 3, wherein the linear motor 2 is installed on the upper and lower cross beams of the tool skeleton 1, and the electric cylinder sliding table 3 is installed on the two side columns of the tool skeleton 1; A constant force clamping assembly 4, which is installed on the linear motor 2 or the electric cylinder sliding table 3 through an auxiliary clamping sliding block 8 to clamp the skin 19; A bistable positioning assembly 5, which is installed on the three middle cross beams of the tool skeleton through the threaded hole ear of the bottom of the compliant bistable mechanism to position the skin 19; A skin positioning stopper 6, which is installed on the auxiliary clamping sliding block 8.

[0022] Embodiment 2 On the basis of embodiment 1, such as Figure 1 and Figure 2As shown, the linear motor 2 and the electric cylinder slide 3 are respectively installed on the cross beams and the upright columns at both ends of the tool skeleton 1, the constant force clamping assembly 4 is installed on the sliders of the linear motor 2 and the electric cylinder slide 3, the bistable positioning assembly 5 is installed on the three cross beams in the middle of the tool skeleton 1, the constant force clamping assembly 4 is movable to different positions to change the layout of the clamping force when processing different sizes of the skin 19, and the bistable positioning assembly 5 can be installed at different positions of the cross beams to change the layout of the positioning points; the skin positioning stop block 6 can be installed on the auxiliary clamping slider, and the bistable positioning assembly 5 and the skin positioning stop block 6 constitute a "2-1" positioning. N

[0023] In order to further optimize the above technical scheme, the constant force clamping assembly 4 comprises an auxiliary clamping slider 8, a compliant constant force mechanism 9, a clamping actuator 10, a micro electric push cylinder 11, a driving clamping electric cylinder slide 12, an auxiliary slide rail-slug 13, and an auxiliary connecting slider 14; the clamping actuator 10 is divided into an upper clamping actuator 101 and a lower clamping actuator 102, and is connected to the auxiliary clamping slider 8 and the guide beam of the compliant constant force mechanism 9 respectively through a double-hole bolt quick-change mode; the micro electric push cylinder 11 is fixed to the compliant constant force mechanism frame 91 and connected with the compliant constant force mechanism preloading block 94 to pre-load the compliant constant force mechanism 9; the driving clamping electric cylinder slide 12 is installed on the auxiliary clamping slider 8; the bottom of the compliant constant force mechanism frame 91 is connected with the slider of the driving clamping electric cylinder slide 12; the auxiliary slide rail-slug 13 is installed on the auxiliary clamping slider 8 in parallel to the driving clamping electric cylinder slide 12; and the auxiliary connecting slider 14 is used to connect the compliant constant force mechanism frame 91 and the auxiliary slide rail-slug 13.

[0024] In order to further optimize the above technical scheme, the clamping actuator 10 is divided into an upper clamping actuator 101 and a lower clamping actuator 102; the output end of the clamping actuator 10 is a rubber ball head; the bottom of the lower clamping actuator 102 is a U-shaped groove structure, and the groove wall has a hole for connecting with the constant force guide beam 95; the bottom of the upper clamping actuator 101 has a protrusion, and the protrusion has a hole for connecting with the auxiliary clamping slider 8.

[0025] Embodiment 3 As Figure 3 ​As shown, the pre-tightening adjustment output constant force size is first performed by the micro electric push cylinder 11 when the skin 19 is clamped, then the clamping electric cylinder slide table 12 is driven to start and input a certain displacement to the compliant constant force mechanism 9 through the slider to achieve clamping; the compliant constant force mechanism 9 provides support for the compliant constant force mechanism 9 through the auxiliary clamping slider 8 and the auxiliary slide rail-slider 13, and assists in sliding when the displacement is input; within a certain displacement range, which is the sum of the displacement generated when clamping and the interference displacement generated when processing after clamping, the constant force clamping assembly 4 can output constant force, and the skin 19 is clamped by using the clamping actuator 10; in order to adapt to the processing needs of skins 19 of different sizes, in addition to adjusting the layout of the constant force clamping assembly 4, on the one hand, the clamping constant force size can be adjusted during pre-tightening, and on the other hand, different size clamping actuators 10 can be quickly replaced to adapt to skins 19 of different sizes.

[0026] When the size of the skin 19 changes greatly in the parallel and vertical linear motor 2 / electric cylinder slide table 3 movement direction, the positions of the sliders on the linear motor 2 and the electric cylinder slide table 3 can be changed and the clamping actuators 10 can be replaced at the same time; when the size of the skin 19 changes little in the parallel linear motor 2 / electric cylinder slide table 3 movement direction, the positions of the corresponding sliders can not be changed, and only the corresponding clamping actuators 10 are replaced according to the size of the skin 19.

[0027] In order to further optimize the above technical solution, the compliant constant force mechanism 9 includes a compliant constant force mechanism frame 91, a negative stiffness beam 92, a positive stiffness beam 93, a pre-loaded block 94, and a constant force guide beam 95; the compliant constant force mechanism frame 91 has holes at the top of both sides for connecting with the auxiliary connecting slider 14, for connecting the compliant constant force mechanism 9 with the auxiliary slide rail-slider 13; the bottom of the compliant constant force mechanism frame 91 is provided with a hole for the micro electric push cylinder 11 to pass through, and the micro electric push cylinder 11 is threadedly connected to the bottom of the compliant constant force mechanism frame 91; The positive stiffness beam 93 is in the shape of a, two horizontal sections are connected to the constant force guide beam and the pre-loaded block respectively; the pre-loaded block is located in the compliant constant force mechanism frame and is arranged directly below the constant force guide beam; The negative stiffness beam 92 is designed in the form of two groups of beams in series, each group being two parallel beams; one end of each negative stiffness beam is connected to the inner surface of the compliant constant force mechanism frame, and the other end is connected to the guide beam; The pre-loaded block 94 has a threaded hole for connecting the end of the micro electric push cylinder 11; the constant force guide beam 95 has a hole for connecting with the clamping actuator 10; the principle of the compliant constant force mechanism 9 outputting constant force is that the sum of the stiffness of the designed positive stiffness beam 93 and the negative stiffness beam 92 is 0 under a certain input displacement.

[0028] As shown, Figure 4 The compliant constant force mechanism 9 is a symmetric mechanism with the center axis of the constant force guide beam 95 as the axis of symmetry; The designed compliant constant force mechanism 9 can change the size of the output constant force within a certain range by changing the pre-tightening displacement. When the required constant force exceeds the design range, different sizes of compliant constant force mechanisms 9 can be replaced.

[0029] When processing the skin 19, a certain interference displacement may occur at the clamping position. The compliant constant force mechanism 9 does not need to rely on sensor feedback or complex control algorithm, but only relies on its own mechanical structure to maintain a constant output force.

[0030] Embodiment 4 On the basis of embodiment 1, in this embodiment, two constant force clamping assemblies 4 are respectively installed on the two columns, and the electric cylinder slide table 3 drives them to move to the specified position, so that the four constant force clamping assemblies 4 on the two columns are symmetrically distributed. Three constant force clamping assemblies 4 are respectively installed on the two beams, and the linear motor 2 drives them to move to the specified position, so that the six constant force clamping assemblies 4 on the two beams are symmetrically distributed. The ten installed constant force positioning assemblies 4 are completely the same except the clamping actuators 10. The same size clamping actuators 10 are used on the two columns, the same size clamping actuators 10 are used on the two beams, and different size positioning actuators 10 are used on the columns and the beams.

[0031] In order to further optimize the above technical solution, the bistable positioning assembly 5 includes a compliant bistable mechanism 15, a positioning actuator 16, a universal swing vacuum chuck with a positioning ball head 17, and a vacuum pressure sensor 18. The compliant bistable mechanism 15 is installed on the middle three beams of the tool skeleton through the threaded ear at the bottom. The positioning actuator 16 is installed on the stable guide beam 153 through the double-hole bolt quick-change way. The universal swing vacuum chuck with a positioning ball head 17 is threadedly connected to the end of the positioning actuator 16. The vacuum pressure sensor 18 is installed on the universal swing vacuum chuck with a positioning ball head 17.

[0032] In order to further optimize the above technical solution, the bottom of the positioning actuator 16 is a U-shaped groove structure, and the groove wall has a hole for connecting the compliant bistable mechanism 15. The top of the positioning actuator 16 has a threaded hole connected to the universal swing vacuum chuck with a positioning ball head 17.

[0033] As shown in Figure 5 When positioning the skin 19, the universal swing vacuum chuck with a positioning ball head 17 adaptively rotates to an angle consistent with the shape of the skin 19, and tightly sucks the skin 19 against the positioning ball head of the universal swing vacuum chuck with a positioning ball head 17. The vacuum pressure sensor 18 installed on the universal swing vacuum chuck with a positioning ball head 17 monitors the suction force. In order to meet the processing needs of different sizes of skins 19, the layout of the bistable positioning assembly 5, i.e. the layout of the skin positioning points, can be changed, and different sizes of positioning actuators 16 and universal swing vacuum chucks with positioning ball heads 17 can be replaced. When the size of the skin 19 changes greatly in the parallel and vertical beam directions, the position of the bistable positioning assembly 5 on the beam and the replacement of different positioning actuators 16 can be changed simultaneously. When the size of the skin 19 changes little in the parallel beam direction, the position of the corresponding bistable positioning assembly 5 can not be changed, and only the corresponding positioning actuator 16 is replaced according to the size of the skin 19.

[0034] In order to further optimize the above technical solution, the compliant bistable mechanism 15 includes a compliant bistable mechanism frame 151, a bistable beam 152, and a stable guide beam 153. The compliant bistable mechanism frame 151 has an ear with a threaded hole at the bottom, which is used to install the compliant bistable mechanism 15 on the middle three beams of the tool skeleton. The bistable beam 152 is designed in a parallel arrangement of two groups of beams, each group of beams behaves as two series-connected bistable beams 152, and each bistable beam 152 is connected to the compliant bistable mechanism frame 151 at one end and to the stable guide beam 153 at the other end. The stable guide beam 153 has a hole for connecting with the positioning actuator 16. The principle of the compliant bistable mechanism 15 is that the mechanism can maintain two stable states, and each change of state requires overcoming a certain energy barrier. When the input energy cannot overcome the designed energy barrier, the compliant bistable mechanism 15 can maintain the current stable state unchanged.

[0035] As shown in Figure 6 , the compliant bistable mechanism 15 is a symmetric mechanism with the center axis of the stable guide beam 153 as the symmetry axis. The designed compliant bistable mechanism 15 can maintain the current stable state unchanged within a certain stress range, and different sizes of compliant bistable mechanisms 15 can be replaced when the input energy can overcome a certain energy barrier.

[0036] Embodiment 5 In this embodiment, the same bistable positioning assembly 5 is installed on each beam, and the positioning actuators 16 on the upper and lower beams of the three beams are the same size, and the positioning actuator 16 on the middle beam is slightly shorter. Five bistable positioning assemblies 5 are installed on each beam. All 15 bistable positioning assemblies 5 jointly limit the movement freedom of the skin 19 in the x direction, the rotation freedom in the z direction, and the rotation freedom in the y direction.

[0037] In order to further optimize the above technical solution, the skin positioning block 6 is L-shaped and is installed on the auxiliary clamping slider 8.

[0038] As shown in Figure 1 and Figure 7 , three skin positioning blocks 6 are used, which together with the bistable positioning assembly 5 form a “ N -2-1” positioning to limit all degrees of freedom of the skin 19. Different sizes of skin positioning stoppers 6 are replaced when processing different sizes of skins 19, and different installation schemes are adopted.

[0039] In this embodiment, one skin positioning stopper 6 is installed on each of the two auxiliary clamping sliding blocks 8 installed on the lower end crossbeam of the tool skeleton 1, to limit the freedom of movement in the z direction and the freedom of rotation in the x direction of the skin 19; one skin positioning stopper 6 is installed on the auxiliary clamping sliding block 8 installed on the left end column of the tool, to limit the freedom of movement in the y direction of the skin 19.

[0040] As shown in FIGS. Figure 8 and Figure 9 , it is a structure schematic diagram of the aircraft skin tool of this embodiment based on the compliant mechanism for clamping the skin.

[0041] The specific working principle of the present application is as follows: 1. Design or select appropriate bistable positioning components, constant force clamping components and skin positioning stoppers according to the size of the skin.

[0042] 2. According to the positioning principle of “ N -2-1”, the inner surface of the skin is positioned by “ N ” bistable positioning components, and the long side and the short side of the skin are positioned by two positioning stoppers and one positioning stopper respectively; the compliant bistable mechanism can maintain the current stable state unchanged only by its own mechanical structure without the need for additional sensors and controllers, the inner surface of the skin is tightly clamped on the positioning ball head by the universal swing vacuum chuck with a positioning ball head, and the vacuum pressure sensor installed on the universal swing vacuum chuck with a positioning ball head detects the adsorption force in real time to ensure that the adsorption force can make the skin tightly close to the positioning ball head and prevent the skin from being deformed due to excessive force.

[0043] 3. In the constant force clamping component, the compliant constant force mechanism can change the output constant force size by changing the pre-tightening displacement size and direction within a certain range, the sliding table for driving clamping inputs displacement to the compliant constant force mechanism to make the compliant constant force mechanism output constant force, and the skin is clamped by the clamping actuator, wherein the input displacement can be within a certain range without the need for accurate control; the compliant constant force mechanism can maintain the current constant force output unchanged only by its own mechanical structure without the need for additional sensors and controllers, and even in the case of a certain disturbance displacement input, the compliant constant force mechanism can maintain the constant force clamping of the skin to ensure the stability of the clamping force without causing the skin to slide or deform.

[0044] 5. After the clamping of the skin is completed, the wall plate assembly is operated for hole making and the like.

[0045] 6. The aircraft skin tool based on the compliant mechanism of the present application can also install other components such as the stringer clamping component through the threaded holes on the tool skeleton, which is used for the assembly operation of the aircraft skin.

[0046] Example 6 The present application is based on the aircraft skin clamping method of the compliant mechanism, the specific operation steps are as follows: Two auxiliary clamping sliders 8 are installed on the lower end beam of the tool skeleton 1, and a skin positioning block 6 is installed on each auxiliary clamping slider 8 to limit the movement freedom degree of the skin in the z direction and the rotation freedom degree in the y direction; a skin positioning block is installed on the auxiliary clamping slider of the tool skeleton column to limit the movement freedom degree of the skin in the x direction; a universal swing vacuum chuck 17 with a positioning ball head is used to adsorb the surface of the skin and further position the skin; and a constant force clamping assembly 4 is used to further clamp the skin.

Claims

1. Aircraft skin tooling based on a compliant mechanism, characterized in that: Comprising: A tooling skeleton (1), the tooling skeleton (1) is welded by two longitudinal columns and five cross beams, and threaded holes are distributed on each column and cross beam for installing components, and the bottom is a support foot (7); A linear motor (2) and an electric cylinder slide (3), the linear motor (2) is installed on the upper and lower cross beams of the tooling skeleton (1), and the electric cylinder slide (3) is installed on the two side columns of the tooling skeleton (1); A constant force clamping component (4), the constant force clamping component is installed on the linear motor (2) or the electric cylinder slide (3) through an auxiliary clamping slider (8) to clamp the skin (19); A bistable positioning component (5), the bistable positioning component (5) is installed on the middle three cross beams of the tooling skeleton through the lug with a threaded hole at the bottom of the compliant bistable mechanism to position the skin (19); A skin positioning stop block (6), the skin positioning stop block (6) is installed on the auxiliary clamping slider (8).

2. The aircraft skin tooling based on a compliant mechanism according to claim 1, characterized in that: The constant force clamping component (4) includes an auxiliary clamping slider (8), a compliant constant force mechanism (9), a clamping actuator (10), a micro electric push cylinder (11), a driving clamping electric cylinder slide (12), an auxiliary slide rail - slider (13), and an auxiliary connecting slider (14); the clamping actuator (10) is divided into an upper clamping actuator (101) and a lower clamping actuator (102), and the upper clamping actuator (101) and the lower clamping actuator (102) are respectively connected to the auxiliary clamping slider (8) and the guiding beam of the compliant constant force mechanism (9) through a double - hole pin quick - change method; the micro electric push cylinder (11) is fixed to the compliant constant force mechanism frame (91) and connected to the pre - loading block (94) of the compliant constant force mechanism (9) to pre - load the compliant constant force mechanism (9); the driving clamping electric cylinder slide (12) is installed on the auxiliary clamping slider (8); the bottom of the compliant constant force mechanism frame (91) is connected to the slider of the driving clamping electric cylinder slide (12); the auxiliary slide rail - slider (13) is installed on the auxiliary clamping slider (8) parallel to the driving clamping electric cylinder slide (12); the auxiliary connecting slider (14) is used to connect the compliant constant force mechanism frame (91) and the auxiliary slide rail - slider (13).

3. The aircraft skin tooling based on a compliant mechanism according to claim 2, characterized in that: The compliant constant force mechanism (9) includes a compliant constant force mechanism frame (91), a negative stiffness beam (92), a positive stiffness beam (93), a pre - loading block (94), and a constant force guiding beam (95); there are holes at the two top ends of the compliant constant force mechanism frame (91) for connecting with the auxiliary connecting slider (14) to connect the compliant constant force mechanism (9) with the auxiliary slide rail - slider (13); there is a hole at the bottom of the compliant constant force mechanism frame (91) for the micro electric push cylinder (11) to pass through, and the micro electric push cylinder (11) is threadedly connected to the bottom of the compliant constant force mechanism frame (91); the positive stiffness beam (93) is in a U - shape, and the connecting ends of the two horizontal segments are respectively connected to the constant force guiding beam (95) and the pre - loading block (94); the pre - loading block (94) is located inside the compliant constant force mechanism frame (91) and is arranged directly below the constant force guiding beam (95); The negative stiffness beam (92) is designed as a series arrangement of two groups of beams, each group consisting of two parallel beams; one end of each negative stiffness beam (92) is connected to the inner surface of the flexible constant force mechanism frame (91), and the other end is connected to the guide beam (95); the preload block (94) has a threaded hole for connecting to the end of the micro electric push cylinder (11); the constant force guide beam (95) has a hole for connecting to the clamping actuator (10).

4. The aircraft skin tooling based on a compliant mechanism according to claim 3, characterized in that: The output ends of the upper clamping actuator (101) and the lower clamping actuator (102) are rubber ball heads; the bottom of the lower clamping actuator (102) is a U-shaped groove structure, and the groove wall has a hole for connecting to the constant force guide beam (95); the bottom of the upper clamping actuator (101) has a protrusion, and the protrusion has a hole for connecting to the auxiliary clamping slider (8).

5. The aircraft skin tooling based on a compliant mechanism according to claim 1, characterized in that: The bistable positioning assembly (5) comprises a compliant bistable mechanism (15), a positioning actuator (16), a universal swing vacuum suction cup (17) with a positioning ball head, and a vacuum pressure sensor (18). The compliant bistable mechanism (15) is mounted on the three middle crossbeams of the tooling frame through a threaded ear piece at the bottom; a positioning actuator (16) is mounted on the stable guide beam (153) of the compliant bistable mechanism (15) through a double-hole pin quick-change method, a universal swing vacuum suction cup (17) with a positioning ball head is mounted at the end of the positioning actuator (16), and a vacuum pressure sensor (18) is mounted on the universal swing vacuum suction cup with a positioning ball head.

6. The aircraft skin tooling based on a compliant mechanism according to claim 5, characterized in that: The compliant bistable mechanism (15) comprises a compliant bistable mechanism frame (151), a bistable beam (152), and a stable guide beam (153); the bottom of the compliant bistable mechanism frame (151) is provided with an ear piece with a threaded hole, which is used to install the compliant bistable mechanism (15) on the middle three crossbeams of the tooling frame; the bistable beam (152) is designed as an arrangement of two groups of beams in parallel, each group of beams is represented by two bistable beams (152) connected in series, one end of each bistable beam (152) is connected to the compliant bistable mechanism frame (151), and the other end is connected to the stable guide beam (153); the stable guide beam (153) is located in the middle of the compliant bistable mechanism frame (151), the upper part passes through the frame and is provided with a hole for connecting to the positioning actuator (16).

7. The aircraft skin tooling based on a compliant mechanism according to claim 6, characterized in that: The bottom of the positioning actuator (16) is a U-shaped groove structure, and a hole is provided on the groove wall for connecting with the upper end of the steady-state guide beam (153); the top of the positioning actuator (16) has a threaded hole connected to the universal swing vacuum suction cup (17) with a positioning ball head.

8. The aircraft skin tooling based on a compliant mechanism according to claim 2, characterized in that: The skin positioning block (6) is L-shaped and is installed between the upper clamping actuator (101) and the lower clamping actuator (102).

9. An assembly method for aircraft skin tooling based on a compliant mechanism, characterized in that: The specific steps are as follows: A skin positioning block (6) is installed on the auxiliary clamping slider of the bottom crossbeam of the tooling frame (1) to limit the skin's freedom of movement in the z direction and the freedom of rotation in the x direction; a skin positioning block is installed on the auxiliary clamping slider of the tooling frame column to limit the skin's freedom of movement in the y direction; a universal swing vacuum suction cup (17) with a positioning ball head adsorbs the skin surface to further position the skin; and a constant force clamping assembly (4) further clamps the skin.

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