Thin plate multi-point clamping fixture and application method thereof

Abstract

The invention discloses a thin plate multi-point clamping fixture and an application method thereof, and relates to the technical field of fixtures. The multi-point clamping fixture for the thin plate comprises a working platform and a clamping unit, the working platform comprises a horizontal base plate; the number of the clamping units is consistent with that of the strip-shaped holes of the horizontal base plate, the clamping units and the strip-shaped holes are in one-to-one correspondence, shells of the clamping units are fixedly connected to the lower end of the horizontal base plate and located at the positions of the corresponding strip-shaped holes, and the strip-shaped holes in the horizontal base plate and the strip-shaped holes of the corresponding clamping units are arranged in an up-and-down opposite mode. The invention discloses a thin-wall annular part end face edge chamfering method. The method is based on a thin-wall annular part chamfering device and a thin plate multi-point clamping fixture. The method comprises the following steps that 1, a workpiece to be machined is clamped; 2, acquiring a processing track; and 3, active avoidance is achieved while grinding is conducted. The clamping and fixing requirements of the chamfering process of the thin-wall annular part (especially a high-voltage transformer electrical insulating part) can be met, and necessary preconditions and structural support are provided for an automatic machining scheme of the chamfering process.

Description

Technical Field

[0001] The present invention relates to the technical field of fixtures, and in particular to a multi-point clamping fixture for thin plate parts and an application method thereof. Background Art

[0002] Thin-walled annular parts are widely used in the fields of aerospace, automotive industry, power transmission equipment, etc. The insulating parts of high-voltage transformers are a typical large-size thin-walled annular part, with an outer diameter of up to 1-2 m. After the end face machining process is completed, there are still many burrs and edges at the edges (inner hole edge and outer circle edge), and chamfering is required.

[0003] In related enterprises, the chamfering of the insulating parts of high-voltage transformers is mainly completed manually, with low efficiency, and the dust generated by grinding floats in the air, causing great damage to the health of personnel.

[0004] In summary, related enterprises are preparing to develop an automated processing plan for the chamfering process of the insulating parts of high-voltage transformers. The difficulty in developing the plan lies in the fixture design, which is mainly reflected in: 1. The stiffness of the insulating parts is relatively low, and a good support and fixing structure needs to be provided; 2. Interference with the cutting tool used for chamfering should be avoided. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a multi-point clamping fixture for thin plate parts and an application method thereof, which can meet the clamping and fixing requirements of the chamfering process of thin-walled annular parts (especially the insulating parts of high-voltage electrical equipment), and provide the necessary prerequisite conditions and structural support for the automated processing plan of the chamfering process.

[0006] The technical solution of the present invention is: a multi-point clamping fixture for thin plate parts, including a working platform and a clamping unit; The working platform includes a horizontal base plate; a plurality of strip-shaped orifices evenly distributed in a ring shape are provided on the horizontal base plate. The smallest circumscribed circle enclosing all the strip-shaped orifices is S, and the extending directions of all the strip-shaped orifices all pass through the center of the smallest circumscribed circle S; the end of the strip-shaped orifice relatively close to the center of the smallest circumscribed circle S is the inner end, and the end of the strip-shaped orifice relatively far from the center of the smallest circumscribed circle S is the outer end; The clamping unit includes a housing, a linear movement driving assembly, a wedge block, a servo motor, a cantilever, a cylinder, and a pressing plate; an inner cavity is provided inside the housing, and a strip-shaped opening communicating with the inner cavity is provided at the upper end of the housing; the linear movement driving assembly is arranged in the inner cavity of the housing and connected to the wedge block, and is used to drive the wedge block to perform reciprocating linear movement along the strip-shaped opening of the housing; the upper end of the wedge block is sequentially provided with a guiding slope surface and a clamping plane from the front end to the rear end, the two ends of the guiding slope surface are respectively a low end and a high end, the guiding slope surface is connected to the clamping plane at the high end, the wedge block is located in the strip-shaped opening of the housing, and the high end of its guiding slope surface extends out above the upper end of the strip-shaped opening; the servo motor is directly or indirectly fixedly connected to the rear side wall of the wedge block, and its shaft extends vertically upward; the rear end of the cantilever is fixedly connected to the shaft of the servo motor, and the front end of the cantilever extends horizontally; the cylinder is fixedly connected to the front end of the cantilever, and its piston rod extends vertically downward; the pressing plate is fixedly connected to the end of the piston rod of the cylinder, and it performs vertical lifting movement under the direct drive of the cylinder, and it performs horizontal circular movement under the indirect drive of the servo motor, and the path of its horizontal circular movement passes directly above the clamping plane of the wedge block; the number of clamping units is the same as and corresponds one by one to the number of strip-shaped orifices of the horizontal substrate, the housing of the clamping unit is fixedly connected to the lower end of the horizontal substrate and is located at the corresponding strip-shaped orifice, the strip-shaped orifices on the horizontal substrate and the strip-shaped openings of the corresponding clamping units are arranged vertically opposite to each other, the wedge block of the clamping unit extends out above the horizontal substrate through the strip-shaped orifice, and the low end of the guiding slope surface of the wedge block is lower than the upper surface of the horizontal substrate.

[0007] A further technical solution of the present invention is that: the housing includes a lower main body and an upper frame connected to the upper end of the lower main body; both the lower main body and the upper frame are strip-shaped members, the upper end of the lower main body is provided with an open mouth, and the upper frame is provided with connecting ears at four corners; the inner cavity is located inside the lower main body, and the strip-shaped opening is provided on the upper frame; the upper frame is fixedly connected to the outer side wall of the lower main body through four connecting ears; when the upper frame and the lower main body are connected to form the housing, the strip-shaped opening of the upper frame is directly above the open mouth of the lower main body, and a hollow area is formed between the upper end surface of the lower main body and the lower end surface of the upper frame.

[0008] A further technical solution of the present invention is that: the linear movement driving assembly includes a lead screw, shaft seats, a nut, guide rails, sliders, a bottom plate, and a motor; both ends of the lead screw are respectively rotatably installed on the shaft seats and are arranged parallel to the strip-shaped opening of the housing, and the two shaft seats are respectively fixedly installed in the inner cavity of the housing; the nut is threadedly connected to the lead screw and fixedly connected to the bottom surface of the wedge block; two guide rails are respectively fixedly installed on both sides of the open mouth of the lower main body of the housing, and two groups of sliders are respectively slidably installed on the two guide rails; the bottom plate is fixedly installed on the upper ends of the two groups of sliders and fixedly connected to the bottom surface of the servo motor; the two guide rails, the two groups of sliders, and the bottom plate are all located in the hollow area between the lower main body and the upper frame; the motor is fixedly installed in the inner cavity of the housing and is connected to one end of the lead screw through a coupling.

[0009] A further technical solution of the present invention is that the clamping unit further includes a cable restraint follower assembly; the cable restraint follower assembly is entirely located on one side outside the housing; the cable restraint follower assembly includes a drag chain, an upper fixing plate, and a lower fixing plate; the drag chain is formed by sequentially hinging a plurality of chain links to form a linear flexible body, the chain links at both ends of the drag chain are respectively defined as a front end chain link and a rear end chain link, a cable passage for the cable to pass through is provided inside the drag chain, the front end chain link is provided with an inlet communicating with the cable passage, and the rear end chain link is provided with an outlet communicating with the cable passage; the front end chain link is fixedly connected to one side of the bottom plate through the upper fixing plate, and the rear end chain link is fixedly connected to the side wall of the lower main body of the housing through the lower fixing plate; the drag chain and the cable passage inside it adaptively deform as the bottom plate moves, and all the cables connected to the servo motor enter the cable passage through the inlet and then pass out of the cable passage through the outlet.

[0010] A further technical solution of the present invention is that the clamping unit further includes a bellows dust cover; the bellows dust cover is a rectangular sheet member with the characteristic of being telescopically deformable, the number of bellows dust covers is two, one ends of the two bellows dust covers are respectively fixedly connected to the lower end of the wedge block and the lower end of the bottom plate, and the other ends of the two bellows dust covers are respectively fixedly connected to the upper ends of the two shaft seats, so as to jointly shield the lead screw; the two bellows dust covers adaptively extend or shorten as the nut moves on the lead screw.

[0011] The technical solution of the present invention is a chamfering method for the end face edge of a thin-walled annular part, based on a chamfering device for thin-walled annular parts and a multi-point clamping fixture for thin plate parts; The chamfering device for thin-walled annular parts includes a base, an industrial robotic arm, a floating grinding head, a gantry crane, and a 3D line-scanning camera; the base is fixedly installed on the ground; the industrial robotic arm is entirely located above the horizontal substrate, the two ends of the industrial robotic arm are respectively a connection end and a clamping end, the connection end is fixedly installed on the upper end of the base, and the movement range of the clamping end covers the upper area of the horizontal substrate; the floating grinding head is fixedly installed at the clamping end of the industrial robotic arm; the 3D line-scanning camera is installed on the gantry crane and is driven by the gantry crane to move, and its scanning field of view within the movement range covers the upper area of the horizontal substrate; Before performing the method, the multi-point clamping fixture for thin plate parts is in the following initial state: ①. In each clamping unit, the wedge blocks are all driven by the corresponding linear movement driving components to move along the corresponding strip-shaped orifice to the limit position, so that the size of the maximum inscribed circle R of all the wedge blocks is the largest; ②. In each clamping unit, the cylinders and the pressure plates are all driven by the corresponding servo motors and are driven by the cantilever to rotate to the outside of the upper region of the maximum inscribed circle R; The method steps are as follows: S01. Clamp the workpiece to be processed: a. Placement: Place the thin-walled annular part to be processed between all the wedges on the upper surface of the horizontal substrate. At this time, the thin-walled annular part is located within the maximum inscribed circle R. b. Positioning: The motors of all the clamping units are started synchronously, driving all the wedges to move along the corresponding strip-shaped orifice towards the inner end of the strip-shaped orifice respectively, so that the size of the maximum inscribed circle R gradually decreases until the guiding slopes of all the wedges come into contact with the outer circular edge of the lower end of the thin-walled annular part. c. Lifting: All the wedges continue to move along the corresponding strip-shaped orifice towards the inner end of the strip-shaped orifice. Under the common guidance of the guiding slopes of all the wedges, the thin-walled annular part is lifted onto the clamping planes of all the wedges. At this time, the lower end face of the thin-walled annular part is jointly supported by the clamping planes of all the wedges. d. Clamping: The servos of all the clamping units are started, driving the pressure plates of all the clamping units to rotate respectively to directly above the upper end face of the thin-walled annular part. Then, the piston rods of the air cylinders of all the clamping units extend, driving the corresponding pressure plates to move downward and finally pressing tightly on the upper end face of the thin-walled annular part. In this step, the lifting height of the thin-walled annular part relative to the upper surface of the horizontal substrate meets the duty cycle height required when the floating grinding head grinds the edge of the end face of the thin-walled annular part. In this step, the pressure plates of all the clamping units are evenly distributed in a ring and press tightly on the upper end face of the thin-walled annular part. S02. Obtain the processing trajectory: Based on the drawing (theoretical dimension parameters) of the thin-walled annular part to be processed and the 3D line-scanning camera vision recognition technology, obtain the grinding trajectory of the target thin-walled annular part (i.e., the movement trajectory of the industrial robotic arm). S03. Chamfering and active avoidance a. Identify the nearest clamping unit: The industrial robotic arm controls the floating grinding head to grind according to the grinding trajectory. During the grinding process, the 3D line-scanning camera is used to identify in real time: the nearest clamping unit along the advancing direction of the grinding trajectory at the current grinding position. b. Release the clamping of the clamping unit: When the nearest clamping unit is identified, the piston rod of the air cylinder of this clamping unit retracts to release the pressing state of this clamping unit on the upper surface of the thin-walled annular part. c. Rotate and avoid by the clamping unit: The servo of this clamping unit is started, driving the cantilever to rotate, and then driving the air cylinder and the pressure plate to rotate to the outside of the vertical upper area of the maximum inscribed circle R, thus avoiding the interference between this clamping unit and the grinding trajectory. d. Rotate and reset by the clamping unit: When it is identified that the floating grinding head has passed through the area where the clamping unit that rotates and avoids is located along the grinding trajectory, the servo of this clamping unit is started, driving the cantilever to rotate, and then driving the air cylinder and the pressure plate to rotate to directly above the upper surface of the thin-walled annular part. e. The clamping unit resumes clamping: Then, the piston rod of the cylinder of the clamping unit extends, driving the pressure plate to move downward and finally pressing tightly against the upper end surface of the thin-walled annular part, thereby restoring the pressing state of the clamping unit on the upper surface of the thin-walled annular part; f. Finish chamfering: Repeat the above sub-steps a - e until the floating grinding head reaches the end of the grinding track and finishes the chamfering of the thin-walled annular part.

[0012] In this step, at most only one clamping unit is in the state of rotating and avoiding at the same time, and the remaining clamping units all maintain the state of clamping the thin-walled annular part.

[0013] The present invention has the following advantages compared with the prior art: 1. It provides a multi-point clamping fixture for thin plate parts, which can meet the clamping and fixing requirements of the chamfering process of thin plate parts (for example, in Embodiment 1, the high-voltage transformer insulation part is taken as an example, and the high-voltage transformer insulation part is a typical thin-walled annular part), providing the necessary prerequisite conditions and structural support for the automated machining solution of the chamfering process.

[0014] 2. The multi-point clamping fixture for thin plate parts adopts a multi-point clamping scheme with annular uniform distribution, and the advantages are mainly reflected in the following aspects: Ⅰ. Stress dispersion: The multi-point clamping with annular uniform distribution can disperse the clamping force to more contact points, and the force on each point is relatively small, thus reducing the stress concentration at a single point and reducing the risk of the workpiece cracking due to excessive local stress; Ⅱ. Deformation easy to control: The thin-walled annular part is prone to elastic deformation when clamped. If the number of clamping points is too small, it is easy to cause the workpiece to have depressions or protrusions between two adjacent clamping points. The multi-point clamping can support the workpiece more evenly and maintain the shape stability of the workpiece. Ⅲ. Vibration suppression: During the grinding process, the cutting force will cause the workpiece to vibrate. The multi-point clamping scheme increases the contact points between the fixture and the workpiece, improves the rigidity of the overall system, and thus reduces the vibration amplitude, which is beneficial to maintaining the machining quality and extending the tool life. Ⅳ. Each clamping unit can not only achieve coordinated linkage but also achieve individual control. Moreover, within a clamping unit, its clamping structure and avoidance structure can also achieve coordinated linkage or individual control, thus greatly expanding the applicable range of the fixture and enabling it to adapt to various regular or irregularly shaped thin plate parts.

[0015] The multi-point clamping scheme adopted by the multi-point clamping fixture for thin plate parts, compared with the existing multi-point clamping schemes, mainly has the following differences: Ⅰ. Lift first and then clamp: The workpiece is lifted to the clamping plane through the guiding slope of the wedge block, so as to form a clearance height between the lower surface of the workpiece and the upper surface of the horizontal substrate, meeting the occupied height required when the floating grinding head grinds the end edge of the thin-walled ring part. Ⅱ. The clamping unit has a rotation avoidance function. During the chamfering process, the clamping units on the grinding track rotate in turn to avoid the floating grinding head (automatically reset and resume clamping after the avoidance), and the floating grinding head can complete the chamfering operation of the end edge of the workpiece in one go according to the predetermined grinding track, improving the chamfering efficiency.

[0016] 3. It provides a method for chamfering the end edge of a thin-walled ring part, realizing the automated processing of the chamfering process of thin-walled ring parts (especially high-voltage transformer electrical insulation parts). The core innovation points are as follows: Ⅰ. Lift the workpiece first and then clamp it to meet the occupied height required for grinding; Ⅱ. Automatically avoid the tool during the chamfering process (automatically reset and resume clamping after the avoidance), and the tool can complete the chamfering operation of the end edge of the workpiece in one go, improving the chamfering efficiency.

[0017] The present invention will be further described below in conjunction with the drawings and embodiments. Brief Description of the Drawings

[0018] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 It is a structural schematic diagram of the clamping unit from the first perspective; Figure 3 It is a structural schematic diagram of the clamping unit from the second perspective; Figure 4 It is an internal structural schematic diagram of the clamping unit; Figure 5 It is a state diagram of the sub-steps of step b in S01; Figure 6 It is a state diagram of the sub-steps of step c in S03.

[0019] Legend Explanation: Horizontal substrate 1; Strip-shaped orifice 11; Housing 2; Strip-shaped opening 20; Lower main body 21; Upper frame 22; Connecting ear 221; Hollowed-out area 23; Lead screw 31, Axle seat 32; Nut 33; Guide rail 34; Slide block 35; Base plate 36; Motor 37; Wedge block 4; Guiding slope 41; Clamping plane 42; Servo 51; Cantilever 52; Cylinder 61; Pressure plate 62; Drag chain 71; Inlet 711; Outlet 712; Upper fixing plate 72; Lower fixing plate 73; Bellows dust cover 8; Thin-walled ring part 100. Detailed Description of the Embodiment Embodiment 1

[0020] AsFigures 1-4 As shown, the multi-point clamping fixture for thin plate parts includes a working platform and a clamping unit.

[0021] The working platform includes a horizontal base plate 1. A plurality of strip-shaped orifices 11 are arranged in a circular and evenly distributed manner on the horizontal base plate 1. The smallest circumscribed circle enclosing all the strip-shaped orifices 11 is S, and the extending directions of all the strip-shaped orifices 11 pass through the center of the smallest circumscribed circle S. The end of the strip-shaped orifice 11 relatively close to the center of the smallest circumscribed circle S is the inner end, and the end of the strip-shaped orifice 11 relatively far from the center of the smallest circumscribed circle S is the outer end.

[0022] The clamping unit includes a housing 2, a linear movement driving assembly, a wedge block 4, a servo motor 51, a cantilever 52, a cylinder 61, and a pressing plate 62. An inner cavity is provided inside the housing 2, and a strip-shaped opening 20 communicating with the inner cavity is provided at the upper end of the housing 2. The linear movement driving assembly is arranged in the inner cavity of the housing 2 and is connected to the wedge block 4 for driving the wedge block 4 to perform reciprocating linear motion along the strip-shaped opening 20 of the housing 2. The upper end of the wedge block 4 is successively provided with a guiding slope 41 and a clamping plane 42 from the front end to the rear end. The two ends of the guiding slope 41 are respectively the low end and the high end, and the guiding slope 41 is connected to the clamping plane 42 at the high end. The wedge block 4 is located in the strip-shaped opening 20 of the housing 2, and the high end of its guiding slope 41 extends out above the strip-shaped opening 20, so that part or all of the guiding slope 41 is exposed above the strip-shaped opening 20. The servo motor 51 is directly or indirectly fixedly connected to the rear side wall of the wedge block 4, and its shaft extends vertically upward. The rear end of the cantilever 52 is fixedly connected to the shaft of the servo motor 51, and the front end of the cantilever 52 extends horizontally. The cylinder 61 is fixedly connected to the front end of the cantilever 52, and its piston rod extends vertically downward. The pressing plate 62 is fixedly connected to the end of the piston rod of the cylinder 61, and it performs vertical lifting motion under the direct drive of the cylinder, and it performs horizontal circular motion under the indirect drive of the servo motor 51. The path of its horizontal circular motion passes directly above the clamping plane 42 of the wedge block 4.

[0023] The number of clamping units is the same as and corresponds one by one to the number of strip-shaped orifices 11 on the horizontal base plate 1. The housing 2 of the clamping unit is fixedly connected to the lower end of the horizontal base plate 1 and is located at the corresponding strip-shaped orifice 11. The strip-shaped orifices 11 on the horizontal base plate 1 and the strip-shaped openings 20 of the corresponding clamping units are arranged vertically opposite to each other. The wedge block 4 of the clamping unit extends out above the horizontal base plate 1 through the strip-shaped orifice 11, and the low end of the guiding slope 41 of the wedge block 4 is lower than the upper surface of the horizontal base plate 1, so as to avoid forming a step between the low end of the guiding slope 41 and the upper surface of the horizontal base plate 1.

[0024] Preferably, the housing 2 includes a lower main body 21 and an upper frame 22 connected to the upper end of the lower main body 21. Both the lower main body 21 and the upper frame 22 are strip-shaped members. The upper end of the lower main body 21 is provided with an opening, and the upper frame 22 is provided with connecting ears 221 at four corners. The inner cavity is located inside the lower main body 21, and the strip-shaped opening 20 is provided on the upper frame 22. The upper frame 22 is fixedly connected to the outer side wall of the lower main body 21 through four connecting ears 221. When the upper frame 22 and the lower main body 21 are connected to form the housing, the strip-shaped opening 20 of the upper frame 22 is directly above the opening of the lower main body 21, and a hollow area 23 is formed between the upper end surface of the lower main body 21 and the lower end surface of the upper frame 22. The hollow area 23 is the installation area for some components of the linear motion driving assembly.

[0025] Preferably, the linear motion driving assembly includes a lead screw 31, shaft seats 32, a nut 33, guide rails 34, sliders 35, a bottom plate 36, and a motor 37. The two ends of the lead screw 31 are respectively rotatably installed on the shaft seats 32 and are arranged parallel to the strip-shaped opening 20 of the housing 2. The two shaft seats 32 are respectively fixedly installed in the inner cavity of the housing 2. The nut 33 is threadedly connected to the lead screw 31 and is fixedly connected to the bottom surface of the wedge block 4. The two guide rails 34 are respectively fixedly installed on both sides of the opening of the lower main body 21 of the housing 2. Two groups of sliders 35 are respectively slidably installed on the two guide rails 34. Each group of sliders 35 includes one or more sliders 35. The bottom plate 36 is fixedly installed on the upper ends of the two groups of sliders 35 and is fixedly connected to the bottom surface of the steering gear 4. The two guide rails 34, the two groups of sliders 35, and the bottom plate 36 are all located in the hollow area 23 between the lower main body 21 and the upper frame 22. The motor 37 is fixedly installed in the inner cavity of the housing 2 and is connected to one end of the lead screw 31 through a coupling. It is used to drive the nut 33 to move back and forth linearly along the lead screw, thereby driving the wedge block 4, the steering gear 51, the cantilever 52, the air cylinder 61, and the pressure plate 62 to move back and forth linearly.

[0026] Preferably, the clamping unit further includes a cable restraint follow-up assembly. The cable restraint follow-up assembly is entirely located on one side outside the housing 2. The cable restraint follow-up assembly includes a drag chain 71, an upper fixing plate 72, and a lower fixing plate 73. The drag chain 71 is formed by sequentially hinging a plurality of chain links to form a linear flexible body. The chain links at both ends of the drag chain 71 are respectively defined as a front-end chain link and a rear-end chain link. The inside of the drag chain 71 is provided with a cable channel for the cable to pass through. The front-end chain link is provided with an inlet 711 communicating with the cable channel, and the rear-end chain link is provided with an outlet 712 communicating with the cable channel. The front-end chain link is fixedly connected to one side of the bottom plate 36 through the upper fixing plate 72, and the rear-end chain link is fixedly connected to the side wall of the lower main body 21 of the housing 2 through the lower fixing plate 73. The drag chain 71 and the cable channel inside it adaptively deform as the bottom plate 36 moves. All the cables connected to the steering gear 51 enter the cable channel through the inlet 711 and then pass out of the cable channel through the outlet 712.

[0027] Preferably, the clamping unit further includes a bellows dust cover 8. The bellows dust cover 8 is a rectangular sheet member with telescopic and deformable characteristics. The number of bellows dust covers 8 is two. One ends of the two bellows dust covers 8 are respectively fixedly connected to the lower end of the wedge block 4 and the lower end of the base plate 36, and the other ends of the two bellows dust covers 8 are respectively fixedly connected to the upper ends of the two shaft seats 32, so as to jointly shield the lead screw 31, thereby preventing dust from entering the lead screw 31. The two bellows dust covers 8 adaptively extend or contract as the nut 33 moves on the lead screw 31.

[0028] A method for chamfering the edge of the end face of a thin-walled annular part is based on a chamfering device for thin-walled annular parts and a multi-point clamping fixture for thin plate parts.

[0029] The chamfering device for thin-walled annular parts includes a base, an industrial robotic arm, a floating grinding head, a gantry crane (not shown in the figure) and a 3D line-scanning camera (not shown in the figure). The base is fixedly installed on the ground. The industrial robotic arm is entirely located above the upper end of the horizontal substrate 1. The two ends of the industrial robotic arm are respectively a connection end and a clamping end. The connection end is fixedly installed on the upper end of the base, and the movement range of the clamping end covers the upper area of the horizontal substrate 1. The floating grinding head is fixedly installed at the clamping end of the industrial robotic arm. The 3D line-scanning camera is installed on the gantry crane and is driven by the gantry crane to move, and its scanning field of view within the movement range covers the upper area of the horizontal substrate 1.

[0030] Before performing the method, the multi-point clamping fixture for thin plate parts is in the following initial state: ①. In each clamping unit, the wedge block 4 is driven by the corresponding linear movement driving component to move along the corresponding strip-shaped hole opening 11 to the limit position, so that the size of the maximum inscribed circle R of all the wedge blocks 4 is the largest.

[0031] ②. In each clamping unit, the air cylinder 61 and the pressure plate 62 are driven by the corresponding servo motor 51 and are driven by the cantilever 52 to rotate to the outside of the upper area of the maximum inscribed circle R in the vertical direction.

[0032] As Figures 5-6 shown, the method steps are as follows: S01. Clamp the workpiece to be processed: a. Placement: Place the thin-walled annular part 100 to be processed between all the wedge blocks 4 on the upper surface of the horizontal substrate 1. At this time, the thin-walled annular part 100 is located within the maximum inscribed circle R; b. Positioning: All the motors 37 of all the clamping units are started synchronously, driving all the wedge blocks 4 to move along the corresponding strip-shaped hole openings 11 and towards the inner ends of the strip-shaped hole openings 11 respectively, so that the size of the maximum inscribed circle R gradually decreases until the guiding slopes 41 of all the wedge blocks 4 all contact the outer circular edge of the lower end of the thin-walled annular part 100; c. Lifting: All the wedges 4 continue to move along the corresponding strip-shaped orifice openings 11 towards the inner ends of the strip-shaped orifice openings 11. Guided jointly by the guiding slopes 41 of all the wedges 4, the thin-walled annular part 100 is lifted onto the clamping planes 42 of all the wedges 4. At this time, the lower end surface of the thin-walled annular part 100 is jointly supported by the clamping planes 42 of all the wedges 4. d. Clamping: The servos 51 of all the clamping units are started simultaneously or without a specific order. The pressure plates 62 of all the clamping units are respectively driven to rotate directly above the upper end surface of the thin-walled annular part 100, and then the piston rods of the air cylinders 61 of all the clamping units extend, driving the corresponding pressure plates 62 to move downward and finally pressing tightly on the upper end surface of the thin-walled annular part 100.

[0033] In this step, the lifting height of the thin-walled annular part 100 relative to the upper surface of the horizontal substrate 1 meets the duty cycle height required when the floating grinding head grinds the edge of the end surface of the thin-walled annular part 100.

[0034] In this step, the pressure plates 62 of all the clamping units are annularly and evenly distributed and pressed tightly on the upper end surface of the thin-walled annular part 100.

[0035] S02. Obtaining the machining trajectory: Based on the drawing (theoretical dimension parameters) of the thin-walled annular part to be machined and the 3D line-scanning camera vision recognition technology, the grinding trajectory of the target thin-walled annular part (i.e., the movement trajectory of the industrial robotic arm) is obtained.

[0036] In this step, the method of obtaining the machining trajectory based on the drawing and vision recognition is a mature existing technology. The specific operation process is briefly described as follows: Prerequisites: ①. Set the scanning start point, scanning end point, and edge type (straight edge or arc edge) of the grinding edge of the thin-walled annular part according to the drawing to generate a scanning path program; ②. Calibrate the 3D line-scanning camera with the floating grinding head; ③. Perform coordinate transformation between the workpiece drawing and the industrial robotic arm; Operation process: ①. Manually set the model of the current thin-walled annular part; ②. Call the corresponding scanning path program to scan the grinding edge of the current thin-walled annular part; ③. Fit straight lines and / or arcs according to the scanning data; ④. Generate the actual grinding trajectory according to the fitting data.

[0037] S03. Chamfering while actively avoiding a. Identifying the nearest clamping unit: The industrial robotic arm controls the floating grinding head to grind according to the grinding trajectory. During the grinding process, the 3D line-scanning camera is used to identify in real time: the nearest clamping unit along the forward direction of the grinding trajectory at the current grinding position. b. Releasing the clamping of the clamping unit: When the nearest clamping unit is identified, the piston rod of the air cylinder 61 of this clamping unit retracts to release the pressing state of this clamping unit on the upper surface of the thin-walled annular part 100. c. Rotational avoidance of the clamping unit: The servo motor 51 of the clamping unit is activated to drive the cantilever 52 to rotate, thereby driving the cylinder 61 and the pressure plate 62 to rotate to the outside of the upper region of the vertical direction of the maximum inscribed circle R, so as to avoid interference between the clamping unit and the grinding trajectory; d. Rotational reset of the clamping unit: When it is recognized that the floating grinding head has passed through the area where the clamping unit that has rotated for avoidance is located along the grinding trajectory, the servo motor 51 of the clamping unit is activated to drive the cantilever 52 to rotate, thereby driving the cylinder 61 and the pressure plate 62 to rotate directly above the upper surface of the thin-walled annular part 100; e. Restoration of clamping by the clamping unit: Then, the piston rod of the cylinder 61 of the clamping unit extends, driving the pressure plate 62 to move downward and finally pressing tightly on the upper end surface of the thin-walled annular part 100, thereby restoring the pressing state of the clamping unit on the upper surface of the thin-walled annular part 100; f. Completion of chamfering: Repeat the above sub-steps a - e until the floating grinding head reaches the end point of the grinding trajectory and completes the chamfering of the thin-walled annular part.

[0038] In this step, at most only one clamping unit is in the state of rotational avoidance at the same time, and the remaining clamping units all maintain the state of clamping the thin-walled annular part.

Claims

1. Multi-point clamping fixture for thin plates, characterized by: It includes a working platform and a clamping unit; The working platform comprises a horizontal base plate; a plurality of strip-shaped openings are arranged on the horizontal base plate in an annular shape and are evenly distributed; the minimum circumscribed circle that includes all the strip-shaped openings is S; the extending directions of all the strip-shaped openings pass through the center of the minimum circumscribed circle S; the end of the strip-shaped opening that is relatively close to the center of the minimum circumscribed circle S is the inner end, and the end of the strip-shaped opening that is relatively far from the center of the minimum circumscribed circle S is the outer end; The clamping unit includes a shell, a linear motion drive assembly, a wedge, a steering gear, a cantilever, a cylinder and a pressure plate; an inner cavity is provided inside the shell, and a strip opening connected to the inner cavity is provided at the upper end of the shell; the linear motion drive assembly is arranged in the inner cavity of the shell and is connected to the wedge, and is used to drive the wedge to perform reciprocating linear motion along the strip opening of the shell; a guide slope and a clamping plane are provided in sequence at the upper end of the wedge from the front end to the rear end, and the two ends of the guide slope are respectively a low end and a high end, and the guide slope is connected to the clamping plane at the high end, and the wedge is located in the strip opening of the shell, and the high end of its guide slope extends out of the upper end of the strip opening; the steering gear is directly or indirectly fixedly connected to the rear end side wall of the wedge, and its machine shaft extends vertically upward; the rear end of the cantilever is fixedly connected to the machine shaft of the steering gear, and the front end of the cantilever is fixedly connected to the machine shaft of the steering gear. The end extends horizontally; the cylinder is fixedly connected to the front end of the cantilever, and its piston rod extends vertically downward; the pressure plate is fixedly connected to the end of the piston rod of the cylinder, and it performs vertical lifting movement under the direct drive of the cylinder, and performs horizontal circular movement under the indirect drive of the servo, and the path of its horizontal circular movement passes directly above the clamping plane of the wedge; the number of clamping units is consistent with the number of strip openings of the horizontal substrate and corresponds one to one, the shell of the clamping unit is fixedly connected to the lower end of the horizontal substrate and is located at the corresponding strip opening, the strip opening on the horizontal substrate is arranged vertically opposite to the corresponding strip opening of the clamping unit, the wedge of the clamping unit extends above the horizontal substrate through the strip opening, and the lower end of the guide slope of the wedge is lower than the upper surface of the horizontal substrate.

2. The multi-point clamping fixture for thin plates as claimed in claim 1, characterized in that: The shell includes a lower body and an upper frame connected to the upper end of the lower body; the lower body and the upper frame are both strip-shaped components, the upper end of the lower body is provided with an opening, and the upper frame is provided with connecting ears at four corners; the inner cavity is located inside the lower body, and the strip opening is provided on the upper frame; the upper frame is fixedly connected to the outer wall of the lower body through four connecting ears; when the upper frame is connected to the lower body to form a shell, the strip opening of the upper frame is located directly above the opening of the lower body, and a hollow area is formed between the upper end surface of the lower body and the lower end surface of the upper frame.

3. The multi-point clamping fixture for thin plates as claimed in claim 2, characterized in that: The linear motion drive assembly includes a screw rod, a shaft seat, a nut, a guide rail, a slider, a base plate and a motor; the two ends of the screw rod are rotatably mounted on the shaft seat and arranged parallel to the strip opening of the shell, and the two shaft seats are fixedly mounted in the inner cavity of the shell; the nut is threadedly connected to the screw rod and fixedly connected to the bottom surface of the wedge block; the two guide rails are fixedly mounted on the two sides of the opening of the lower body of the shell, and the two groups of sliders are slidably mounted on the two guide rails; the base plate is fixedly mounted on the upper ends of the two groups of sliders and fixedly connected to the bottom surface of the servo; the two guide rails, the two groups of sliders and the base plate are all located in the hollow area between the lower body and the upper frame; the motor is fixedly mounted in the inner cavity of the shell and connected to one end of the screw rod through a coupling.

4. The multi-point clamping fixture for thin plates as claimed in claim 3, characterized in that: The clamping unit also includes a cable restraint follower assembly; the cable restraint follower assembly is located on one side of the exterior of the shell as a whole; the cable restraint follower assembly includes a drag chain, an upper fixed plate and a lower fixed plate; the drag chain is formed by a plurality of chain links hinged in sequence to form a linear flexible body, the chain links at both ends of the drag chain are respectively defined as front chain links and rear chain links, a cable channel for the cables to pass through is provided inside the drag chain, the front chain link is provided with an entrance connected to the cable channel, and the rear chain link is provided with an exit connected to the cable channel; the front chain link is fixedly connected to one side of the base plate through the upper fixed plate, and the rear chain link is fixedly connected to the side wall of the lower body of the shell through the lower fixed plate; the drag chain and the cable channel inside it deform adaptively with the movement of the base plate, and all cables connected to the servo enter the cable channel through the entrance and then pass through the cable channel through the exit.

5. The multi-point clamping fixture for thin plates as claimed in claim 4, characterized in that: The clamping unit also includes an accordion dust cover; the accordion dust cover is a rectangular sheet component with telescopic deformation characteristics. There are two accordion dust covers, one end of the two accordion dust covers are respectively fixedly connected to the lower end of the wedge block and the lower end of the base plate, and the other ends of the two accordion dust covers are respectively fixedly connected to the upper ends of the two shaft seats, thereby jointly shielding the screw rod; the two accordion dust covers adaptively extend or shorten as the nut moves on the screw rod.

6. A method for chamfering the edge of the end face of a thin-walled annular component, based on a chamfering device for a thin-walled annular component and a multi-point clamping fixture for a thin plate component; Its characteristics are: thin wall The annular component chamfering device comprises a base, an industrial robot arm, a floating grinding head, a gantry crane and a 3D line scan camera; the base is fixedly installed on the ground; the industrial robot arm is located at the upper end of a horizontal substrate as a whole, and the two ends of the industrial robot arm are a connecting end and a clamping end respectively, the connecting end is fixedly installed at the upper end of the base, and the movement range of the clamping end covers the upper area of ​​the horizontal substrate; the floating grinding head is fixedly installed at the clamping end of the industrial robot arm; the 3D line scan camera is installed on the gantry crane and is driven to move by the gantry crane, and its scanning field of view within the moving range covers the upper area of ​​the horizontal substrate; Before executing the method, the multi-point clamping fixture for thin plate parts is in the following initial state: ①. The wedges in each clamping unit are driven by the corresponding linear motion drive assembly to move to the limit position along the corresponding strip-shaped orifice, so that the size of the maximum inscribed circle R of all wedges is maximized; ②. The cylinder and the pressure plate in each clamping unit are driven by the corresponding steering gear and driven by the cantilever to rotate to the outside of the vertical upper area of ​​the maximum inscribed circle R; The steps are as follows: S01. Clamp the workpiece to be processed: a. Placement: Place the thin-walled annular component to be processed between all wedges on the upper surface of the horizontal substrate, so that the thin-walled annular component is located in the maximum inscribed circle R; b. Positioning: The motors of all the clamping units are started synchronously to drive all the wedges to move along the corresponding strip-shaped openings toward the inner ends of the strip-shaped openings, so that the size of the maximum inscribed circle R is gradually reduced until the guide slopes of all the wedges contact the outer circular edge of the lower end of the thin-walled annular member; c. Lifting: All wedges continue to move along the corresponding strip-shaped orifices toward the inner end of the strip-shaped orifices, and the thin-walled annular component is lifted to the clamping plane of all wedges through the common guidance of the guiding slopes of all wedges. At this time, the lower end surface of the thin-walled annular component is jointly supported by the clamping planes of all wedges; d. Clamping: The steering gears of all clamping units are started, driving the pressure plates of all clamping units to rotate to the top of the upper end surface of the thin-walled annular component respectively, and then the piston rods of the cylinders of all clamping units are extended, driving the corresponding pressure plates to move downward and finally press on the upper end surface of the thin-walled annular component; In this step, the height of the thin-walled annular member relative to the upper surface of the horizontal substrate satisfies the required occupation height when the floating grinding head grinds the edge of the end surface of the thin-walled annular member; In this step, the pressure plates of all the clamping units are evenly distributed in an annular shape and pressed tightly against the upper end surface of the thin-walled annular member; S02, obtaining a processing trajectory: based on a drawing of a thin-walled annular part to be processed and 3D line scan camera visual recognition technology, obtaining a grinding trajectory of the target thin-walled annular part; S03, active avoidance while grinding: a. Identify the nearest clamping unit: The industrial robot arm controls the floating grinding head to grind along the grinding trajectory. During the grinding process, the 3D line scan camera is used to identify in real time: the nearest clamping unit along the grinding trajectory at the current grinding position; b. The clamping unit releases the clamping: when the nearest clamping unit is identified, the piston rod of the cylinder of the clamping unit retracts to release the clamping unit from pressing the upper surface of the thin-walled annular part; c. Clamping unit rotation avoidance: The servo of the clamping unit is started to drive the cantilever to rotate, thereby driving the cylinder and the pressure plate to rotate to the outside of the vertical upper area of ​​the maximum inscribed circle R, thereby avoiding interference between the clamping unit and the grinding track; d. Clamping unit rotation reset: When it is recognized that the floating grinding head passes through the area of ​​the clamping unit for rotation avoidance along the grinding trajectory, the servo of the clamping unit is started to drive the cantilever to rotate, thereby driving the cylinder and the pressure plate to rotate to just above the upper surface of the thin-walled annular part; e. The clamping unit resumes clamping: Then the piston rod of the cylinder of the clamping unit extends, driving the pressure plate to move downward and finally press on the upper end surface of the thin-walled annular part, thereby restoring the clamping state of the clamping unit on the upper surface of the thin-walled annular part; f. Complete chamfering: Repeat the above steps ae until the floating grinding head reaches the end of the grinding track and completes the chamfering of the thin-walled ring part; In this step, at most only one clamping unit is in the state of rotation avoidance at the same time, and the other clamping units all maintain the state of clamping the thin-walled annular part.

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