Automatic support removing and grinding method for skin interlayer workpiece

Abstract

The invention discloses an automatic support-removing polishing method for a skin interlayer workpiece, which aims at different support structures of a dot matrix, a rib plate and a grid of a skin interlayer workpiece product, and carries out support-removing polishing by taking and replacing corresponding different tools in a tool library along with a polishing path and corresponding to different parameter packets. And in the polishing process, the surface state is monitored on line, and support removing polishing parameters are regulated and controlled. Full-path automatic removing and grinding of different supporting types are achieved, the operation process is more stable, the quality controllability is high, the machining quality problem caused by individual factors and accidental factors is avoided, the device is suitable for small-batch development and continuous production of large-scale batch products, and it is avoided that operators work under the conditions of harmful factors such as dust and noise for a long time.

Description

Technical Field

[0001] The invention relates to an automatic support removal and grinding method for a skin sandwich workpiece, and belongs to the field of additive manufacturing post-processing. Background Art

[0002] The skin sandwich workpiece uses deflection in the airflow to generate balance force and control force to manipulate the flight posture. Based on aerodynamic and other design requirements, the skin sandwich workpiece structure is skin + internal honeycomb / lattice / grid structure. Among them, the skin is often a free-form surface or a combination of different inclined surfaces, and the thickness is ≤1mm; the inner cavity structure has poor adaptability to traditional processing. Therefore, metal laser additive manufacturing has become an advantageous means of processing and preparing skin sandwich workpiece products.

[0003] However, due to the process limitations of metal laser additive manufacturing, it is inevitable to add dimensional structures such as ribs, lattices, solid / non-solid supports such as blocks, contours, cones, networks, and other process structures. In order to maintain the dimensional and positional accuracy required for the design of the skin sandwich workpiece, various supporting dimensional structures have a certain strength and solid density, which often makes it difficult to remove the support and polish after metal laser additive manufacturing. Patent CN113211263A discloses a grinding device for additive manufacturing, involving a base, a limit device, an extension device and a reciprocating device, which can realize the grinding of the entire surface of the material and improve the grinding efficiency. However, the shape of the clamped workpiece is limited and cannot adapt to the skin sandwich workpiece augmented support scheme; Patent CN110000382B discloses a method for removing support structures in titanium alloys in additive manufacturing, involving high-pressure gas powder cleaning, full-surface pickling and support chemical corrosion and abrasive flow polishing. Although the adverse effects of the H element are eliminated in the final heat treatment process, the material removal during the pickling and support removal process cannot be accurately controlled, and thus the mechanical properties and skin wall thickness requirements of the product at the time of delivery cannot be guaranteed; Patent CN218430025U discloses a device for removing supports for additively manufactured molded parts, involving ultrafast laser focusing and support laser cutting, and its removal efficiency and accuracy are limited by the material-laser absorption rate and the three-dimensional focusing error in the coordinated motion of the galvanometer-platform. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, to provide a method for automatically removing support and grinding a skin sandwich workpiece, and to improve the problem of limited post-processing efficiency and precision of existing additively manufactured skin sandwich workpiece products.

[0005] The technical solution of the present invention is: a method for automatically removing support and grinding a skin sandwich workpiece, comprising:

[0006] The skin sandwich workpiece additive blank is clamped to the working platform under the robot arm, and the blank is laser 3D scanned. The point cloud obtained by the scan is compared with the theoretical blank of the product to obtain the support area to be removed, and the support area to be removed is divided into K working areas. Each current working area n includes a test tool path, an area n cycle support removal path, a tool change path, and a fast positioning path, where 1≤n≤K-1;

[0007] The spindle at the end of the robot arm starts to rotate, and the trial knife sub-path is first carried out according to the planned path to verify the rationality of the path, and then enters the area n to cycle the support removal sub-path. A single pass of support removal grinding is performed in area n, and the corresponding parameter package is called. The dot matrix is ​​brushed with a wire brush, the rib plate is milled at the root, and the grid support is impacted with the root teeth. During the grinding process, the surface state is monitored online and the support removal grinding parameters are adjusted. It is judged whether the support removal grinding in area n is completed. If not, the cycle continues. If completed, it enters the next step.

[0008] After area n is completed, the spindle stops rotating and moves to the safe tool change point m. The tool magazine sends the new tool to the safe tool change point m' for tool change operation. After completion, the spindle quickly moves to the area n+1 cycle to support the starting point with the rapid positioning sub-path, and starts rotating to enter the area n+1 cycle to support the sub-path;

[0009] Determine whether all areas in the support area to be removed are completed. If completed, end. If not completed, repeat the area switching grinding step until all areas are completed.

[0010] Preferably, in the tool library:

[0011] The dots are removed using a wire brush, which is a cylindrical wire brush with a diameter of 1 / 10-1 / 5 of the horizontal projection length of the dot array area;

[0012] The ribs are removed by a milling cutter, which is a T-shaped milling cutter with an effective cutting radius of 1.2-2 times the thickness of the connection between the ribs and the blank;

[0013] The grid structure is removed using a punch, which is a pointed punch with a tip angle of ≤30° and a rod diameter of 5-15mm.

[0014] Preferably, in the parameter package:

[0015] When removing with dot-matrix brush, the parameters are spindle speed 1000-5000rpm, feed rate 0.3-0.8mm;

[0016] When the rib root is milled and removed, the parameters are cutting speed 80-120 mm / s, radial cutting width 0.4-2 mm, and feed per tooth 0.3-1 mm / z;

[0017] When the mesh support impacts the root teeth for removal, the parameters are nominal pressure 25-100t and impact frequency 30-70 times / min.

[0018] Preferably, when monitoring the surface state online during the grinding process, a line laser measuring instrument is used to capture the surface contour size of the product after support removal grinding, and compared with the theoretical profile of the blank to determine whether the area has completed support removal grinding, over-grinding or under-grinding.

[0019] Preferably, the robot arm comprises a main robot arm and an end-circulation grinding device, wherein:

[0020] The main robot arm includes: a first joint, a second joint and a third joint, the first joint rotates in the Z direction, the second joint rotates in the X direction, and the third joint rotates in the Y direction;

[0021] The end-circulation grinding device is responsible for the feeding, rotation, and X- and Y-direction movement of the spindle during grinding;

[0022] The X direction represents the long-range direction parallel to the work surface, the Y direction represents the short-range direction parallel to the work surface, and the Z direction represents the vertical direction perpendicular to the work surface.

[0023] Preferably, the end cycle grinding device includes: a spindle 3+1 motion mechanism, a line laser measuring instrument and an atomizing cooling device, wherein the spindle 3+1 motion mechanism includes a spindle, a pneumatic motor and a mechanical sensor; specifically:

[0024] The spindle is installed at the end of the pneumatic motor through a floating unit and is driven to rotate by the pneumatic motor; the mechanical sensor is located at the rear end of the floating unit;

[0025] The spindle 3+1 motion mechanism moves in the grinding area and realizes constant force floating grinding through pneumatic motors and mechanical sensors; the line laser measuring instrument is installed behind the spindle, and data is transmitted to the main control computer via a data cable; the mist cooling device is installed beside the spindle, and the tool is clamped on the spindle with a quick-change tool holder.

[0026] Preferably, when adjusting the support removal grinding parameters, the end cycle grinding device is used to achieve constant force floating grinding. The main control computer reduces the feed rate when it determines that the grinding is over-grinding based on the obtained data, and increases a cycle when it determines that the grinding is under-grinding.

[0027] Preferably, the planned sub-paths are specifically:

[0028] Trial tool path: After path planning, the spindle executes the path with the same parameters as the formal path at a vertical height of 10-30mm from the overall contour of the blank, and only cycles once to verify the rationality of the path;

[0029] Area n cyclic support removal sub-path: execute the cyclic support removal grinding path until the online monitoring surface state determines that the corresponding spatial path is completed;

[0030] Tool change path: After completing the area n cycle to remove the support, complete the spatial path required for tool change; When changing the tool: the robot moves the spindle to the safe tool change point m, waits for the tool library to complete the retrieval and replacement of the tool, and then the robot moves the spindle to the positioning area n+1 cycle to remove the support starting point;

[0031] Rapid positioning of sub-paths: After the spindle completes a path, it stops rotating, rises to the height of the test tool sub-path, and is then moved by the robotic arm to the spatial path corresponding to the next area with the shortest straight-line distance.

[0032] Preferably, the safe tool change point m is a point in the space outside the horizontal projection area after the additive blank is clamped and at the height of the test tool path, which does not interfere with the existing device. After completing the area n cycles to remove the support, the spindle is moved to this point by the robot arm;

[0033] Safe tool change point m': outside the horizontal projection area after the additive blank is clamped, at the height of the test tool path, ensuring that there is no interference with any device, and the spatial distance from the safe tool change point m is less than the tool change operation distance of the holding mechanism in the tool library. After completing the "area n cycle support removal", the tool library will move the new tool to this point.

[0034] Preferably, the support area to be removed is divided into K areas, and the area division is performed in the order of dot matrix, rib plate, and grid support.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] (1) The support removal and grinding path of the present invention can adapt to different types of supports, realize full-path automation, make the operation process more stable, and have high quality controllability, thus avoiding processing quality problems caused by individual factors and accidental factors;

[0037] (2) The present invention can realize small-batch research and development and continuous production of large-scale batch products, avoiding operators from working under harmful factors such as dust and noise for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Automatic support removal and grinding process for skin sandwich workpieces;

[0039] Figure 2 This is a schematic diagram of the support for the skin sandwich workpiece product.

[0040] Explanation of the reference numerals: 1 - skin sandwich workpiece additive blank body; 2 - lattice; 3 - rib plate; 4 - grid support. DETAILED DESCRIPTION

[0041] The present invention proposes an automatic support removal and grinding method for skin sandwich workpieces. According to the different support structure partitions of the skin sandwich workpiece products, such as lattice, ribs and grids, a "3+4" robotic arm is used to retrieve and replace different tools in the tool library along the grinding path and perform support removal and grinding corresponding to different parameter packages. The surface state is monitored online during the grinding process to adjust the support removal and grinding parameters.

[0042] The "3+4" robotic arm includes a main robotic arm and an end-circulation grinding device; the main robotic arm has a first joint Z-direction rotation, a second joint X-direction rotation and a third joint Y-direction rotation; the end-circulation grinding device includes spindle rotation, feeding and spindle X-direction and Y-direction movement, wherein the X-direction represents the long-range direction parallel to the work surface, the Y-direction represents the short-range direction parallel to the work surface, and the Z-direction represents the vertical direction perpendicular to the work surface.

[0043] The grinding path is obtained by comparing the point cloud obtained by line laser 3D scanning with the theoretical blank of the product to obtain the support area to be removed, and the support area to be removed is divided into K areas. Each area n of the current operation is divided in the order of "dot matrix-rib plate-grid support". The planned path includes "trial tool" sub-path, "area n cycle support removal" sub-path, "tool change" sub-path and "quick positioning" sub-path, where 1≤n≤K-1.

[0044] In the tool library, the dot matrix is ​​removed by a wire brush, which is a cylindrical wire brush with a diameter of 1 / 10-1 / 5 of the horizontal projection length of the dot matrix area; the rib plate is removed by a milling cutter, which is a T-shaped milling cutter with an effective cutting radius of 1.2-2 times the thickness of the connection between the rib plate and the blank; the grid structure is removed by a punch, which is a pointed punch with a sharp angle of ≤30° and a rod diameter of 5-15mm.

[0045] The different tools are retrieved and replaced. When the spindle completes the area n cycle to support, it stops rotating and quickly positions to the safe tool change point m. At this time, the tool magazine sends the new tool to the safe tool change point m', the spindle and the tool magazine release the tool, the tool magazine holding mechanism changes the tool, the spindle and the tool magazine tighten the tool, and the tool tightening completes the spindle's rapid positioning to the area n+1 cycle to support the initial position, the spindle starts rotating, and the tool magazine resets.

[0046] The parameter package includes dot-matrix brushing removal, with the parameters of electric spindle speed 1000-5000rpm and feed rate 0.3-0.8mm; rib root milling removal, with the parameters of cutting speed 80-120mm / s, radial cutting width 0.4-2mm, and feed rate per tooth 0.3-1mm / z; grid support impact root tooth removal, with the parameters of nominal pressure 25-100t and impact frequency 30-70 times / min.

[0047] The online monitoring of the surface state uses a line laser measuring instrument to capture the surface contour size of the product after support removal and grinding, and compares it with the theoretical profile of the blank to determine whether the area has completed support removal and grinding, over-grinding or under-grinding.

[0048] The control of the support-free grinding parameters is that the spindle is installed on the pneumatic motor shaft, and the constant force floating grinding is realized by using a mechanical sensor, and the feed rate is reduced when it is judged to be over-grinding, and a cycle is added when it is judged to be under-grinding.

[0049] The end cycle grinding device includes: a spindle 3+1 motion mechanism, a line laser measuring instrument and an atomizing cooling device, wherein the spindle 3+1 motion mechanism includes a spindle, a pneumatic motor and a mechanical sensor; specifically:

[0050] The spindle is installed at the end of the pneumatic motor through a floating unit and is driven to rotate by the pneumatic motor; the mechanical sensor is located behind the floating unit; the spindle 3+1 motion mechanism realizes movement in the grinding area and realizes constant force floating grinding through the pneumatic motor and the mechanical sensor. The line laser measuring instrument is installed behind the spindle and transmits data to the main control computer via a data cable. The mist cooling device is installed beside the spindle, and the tool is clamped on the spindle by a quick-change tool holder.

[0051] The "trial tool" sub-path described above is a path where, after path planning, the spindle executes a path with the same parameters as the formal path and only cycles once at a vertical height of 10-30 mm from the overall contour of the blank to verify the rationality of the path.

[0052] The "region n cyclic support removal" sub-path executes a cyclic support removal grinding path within a certain type of support region until the online monitoring of the surface state determines that the corresponding spatial path is completed.

[0053] The "tool change" sub-path described completes the spatial path required for tool change after completing the area n cycle to support; when changing the tool: the robot arm moves the spindle to the safe tool change point m, waits for the tool library to complete the retrieval and replacement of the tool, and then the robot arm moves the spindle to the starting point of the area n+1 cycle to support.

[0054] The "area n+1 cycle support removal" sub-path is the next area to perform support removal grinding after completing the "area n cycle support removal" and "tool change" sub-paths.

[0055] In the "quick positioning" sub-path, after the spindle completes a path, the spindle stops rotating, rises to the height of the "test knife" sub-path, and is then moved by the robotic arm to the spatial path corresponding to the next area with the shortest straight-line distance.

[0056] The safe tool change point m is outside the horizontal projection area after the additive blank is clamped, at the height of the "trial tool" path, and is a point in the space that does not interfere with the existing device. After completing the "area n cycle to remove support", the spindle is moved to this point by the robot arm.

[0057] The safe tool change point m' is outside the horizontal projection area after the additive blank is clamped, at the height of the "test tool" path, to ensure that it does not interfere with any device, and the spatial distance from the safe tool change point m is less than the tool change operation distance of the holding mechanism. After completing the "area n cycle support removal", the tool library will move the new tool to this point.

[0058] Example:

[0059] A method for automatically removing support and grinding a skin sandwich workpiece, for example, Figure 2 As shown: 1- The additive blank body of the skin sandwich workpiece can be divided into areas such as dot matrix 2, ribs 3 and different grid support structures 4. By using the "3+4" robotic arm, different tools in the tool library can be retrieved and replaced along the grinding path, and support removal and grinding can be performed according to different parameter packages. The surface status can be monitored online during the grinding process to adjust the support removal grinding parameters.

[0060] The "3+4" robotic arm includes a main robotic arm, which has a first joint Z-direction rotation, a second joint X-direction rotation and a third joint Y-direction rotation; an end-circulation grinding device, which includes spindle rotation, feeding and spindle X-direction and Y-direction movement, wherein the X-direction represents the long-range direction parallel to the work surface, the Y-direction represents the short-range direction parallel to the work surface, and the Z-direction represents the vertical direction perpendicular to the work surface.

[0061] The grinding path is obtained by comparing the point cloud obtained by line laser three-dimensional scanning with the theoretical blank of the product to obtain the support area to be removed, and is planned in the order of "dot matrix-rib plate-grid support" to include "trial tool" sub-path, "area 1 cyclic support removal" sub-path, "tool change 1" sub-path, "area 2 cyclic support removal" sub-path, "tool change 2" sub-path, "area 2 cyclic support removal" sub-path and "quick positioning" sub-path.

[0062] In the tool library, the dot matrix in area 1 is removed using a wire brush. The wire brush is a cylindrical wire brush with a diameter of 1 / 5 of the horizontal projection length of the dot matrix area and a diameter of 16 mm. The ribs are removed using a milling cutter. The milling cutter is a T-shaped milling cutter with an effective cutting radius of twice the thickness of the connection between the rib and the blank and an effective cutting radius of 3 mm. The grid structure is removed using a punch. The punch is a pointed punch with a sharp angle of 25° and a rod diameter of 10 mm.

[0063] The different tools are retrieved and replaced. When the spindle completes the cycle of area 1 to remove support, it stops rotating and quickly positions to the safe tool change point 1. At this time, the tool library sends the T-shaped milling cutter to the safe tool change point 1', the spindle loosens the wire brush, the tool library loosens the T-shaped milling cutter, and the tool library supports the tool change mechanism. The spindle tightens the T-shaped milling cutter, the tool library tightens the wire brush, and the tool tightens the tool to complete the rapid positioning of the spindle to the initial position of the cycle of area 2 to remove support, the spindle starts to rotate, and the tool library resets; when the spindle completes the cycle of area 2 to remove support, it stops rotating and quickly positions to the safe tool change point 2. At this time, the tool library sends the punch to the safe tool change point 2', the spindle loosens the T-shaped milling cutter, the tool library loosens the punch, and the tool library supports the tool change mechanism. The spindle tightens the T-shaped milling cutter, the tool library tightens the punch, and the tool tightens the tool to complete the rapid positioning of the spindle to the initial position of the cycle of area 3 to remove support, the spindle starts to feed, and the tool library resets.

[0064] The parameter package includes dot-matrix brushing removal, with the parameters of electric spindle speed of 3000 rpm and feed rate of 0.5 mm; rib root milling removal, with the parameters of cutting speed of 90 mm / s, radial cutting width of 0.5 mm, and feed rate of 1 mm / z per tooth; and grid support impact root tooth removal, with the parameters of nominal pressure of 25 t and impact frequency of 50 times / min.

[0065] The online monitoring of the surface state uses a line laser measuring instrument to capture the surface contour size of the product after support removal and grinding, and compares it with the theoretical profile of the blank to determine whether the area has completed support removal and grinding, over-grinding or under-grinding.

[0066] The control of the support-free grinding parameters is that the spindle is installed on the pneumatic motor shaft, and the constant force floating grinding is realized by using a mechanical sensor, and the feed rate is reduced when it is judged to be over-grinding, and a cycle is added when it is judged to be under-grinding.

[0067] The circulating grinding device has a spindle XY motion mechanism to realize movement within the grinding area and realize constant force floating grinding through a pneumatic motor and a mechanical sensor. A line laser measuring instrument is installed behind the spindle and transmits data to a main control computer via a data cable. An atomizing cooling device is installed beside the spindle and the tool is clamped on the spindle by a quick-change tool holder.

[0068] The "trial tool" sub-path described above is a path planning in which the spindle moves at a vertical height of 10 mm from the overall contour of the blank, along a path with the same parameters as the formal path and a cycle path support once, to verify the rationality of the path.

[0069] The "area 1 cyclic support removal" sub-path executes a cyclic support removal grinding path within the lattice support area until the online monitoring surface state is determined to be completed.

[0070] The "tool change" sub-path is that after completing the area 1 cycle to remove support, the robot arm moves the spindle to the safe tool change point 1, and waits for the tool library to complete the retrieval and tool replacement, and then the robot arm moves the spindle to the area 2 cycle to remove support starting point; after completing the area 2 cycle to remove support, the robot arm moves the spindle to the safe tool change point 2, and waits for the tool library to complete the retrieval and tool replacement, and then the robot arm moves the spindle to the area 3 cycle to remove support starting point.

[0071] The "area 2 cyclic support removal" sub-path is the next area to perform support removal grinding after completing the "area 1 cyclic support removal" and "tool change" sub-paths.

[0072] The "area 3 cyclic support removal" sub-path is the next area to perform support removal grinding after completing the "area 2 cyclic support removal" and "tool change" sub-paths.

[0073] In the "quick positioning" sub-path, after the spindle completes a path, the spindle stops rotating, rises to the height of the "test knife" sub-path, and is then moved to the next area by the robotic arm in the shortest straight line distance.

[0074] The safe tool change point 1 is located outside the horizontal projection area after the additive blank is clamped, at the height of the "test tool" path, and is a point in the space that does not interfere with any device. After completing the "area 1 cycle to remove support", the spindle is moved to this point by the robot arm.

[0075] The safe tool change point 1' is outside the horizontal projection area after the additive blank is clamped, at the height of the "test tool" path, to ensure that it does not interfere with any device, and the spatial distance from the safe tool change point 1 is less than the tool change operation distance of the holding mechanism. After completing the "area 1 cycle de-support", the tool library will move the new tool to this point.

[0076] The safe tool change point 2 is located outside the horizontal projection area after the additive blank is clamped, at the height of the "test tool" path, and is a point in the space that does not interfere with any device. After completing the "area 2 cycle to remove support", the spindle is moved to this point by the robot arm.

[0077] The safe tool change point 2' is outside the horizontal projection area after the additive blank is clamped, at the height of the "test tool" path, to ensure that it does not interfere with any device, and the spatial distance from the safe tool change point 2 is less than the tool change operation distance of the holding mechanism. After completing the "area 2 cycle desupport", the tool library will move the new tool to this point.

[0078] The present invention adopts flexible floating grinding technology to integrate the advantages of high flexibility and high automation of robots into the field of supporting grinding. It has the advantages of high productivity, high quality and high stability. It can shorten the cycle of product modification and replacement, reduce the corresponding investment in equipment, and reduce occupational disease hazards such as noise and dust in the workers' operating environment. It is an effective means to achieve intelligence and greening.

[0079] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in this field.

Claims

1. A method for automatically removing support and grinding a skin sandwich workpiece, characterized in that: include: The skin sandwich workpiece additive blank is clamped to the working platform under the robot arm, and the blank is laser 3D scanned. The point cloud obtained by the scan is compared with the theoretical blank of the product to obtain the support area to be removed, and the support area to be removed is divided into K working areas. Each current working area n includes a test tool path, an area n cycle support removal path, a tool change path, and a fast positioning path, where 1≤n≤K-1; The spindle at the end of the robot arm starts to rotate, and the trial knife sub-path is first carried out according to the planned path to verify the rationality of the path, and then enters the area n to cycle the support removal sub-path. A single pass of support removal grinding is performed in area n, and the corresponding parameter package is called. The dot matrix is ​​brushed with a wire brush, the rib plate is milled at the root, and the grid support is impacted with the root teeth. During the grinding process, the surface state is monitored online and the support removal grinding parameters are adjusted. It is judged whether the support removal grinding in area n is completed. If not, the cycle continues. If completed, it enters the next step. After area n is completed, the spindle stops rotating and moves to the safe tool change point m. The tool magazine sends the new tool to the safe tool change point m' for tool change operation. After completion, the spindle quickly moves to the area n+1 cycle to support the starting point with the rapid positioning sub-path, and starts rotating to enter the area n+1 cycle to support the sub-path; Determine whether all areas in the support area to be removed are completed. If completed, end. If not completed, repeat the area switching grinding step until all areas are completed.

2. The method for automatically removing support and grinding a skin sandwich workpiece according to claim 1, characterized in that: In the tool library: The dots are removed using a wire brush, which is a cylindrical wire brush with a diameter of 1 / 10-1 / 5 of the horizontal projection length of the dot array area; The ribs are removed by a milling cutter, which is a T-shaped milling cutter with an effective cutting radius of 1.2-2 times the thickness of the connection between the ribs and the blank; The grid structure is removed using a punch, which is a pointed punch with a tip angle of ≤30° and a rod diameter of 5-15mm.

3. The method for automatically removing support and grinding a skin sandwich workpiece according to claim 1, characterized in that: In the parameter package: When removing with dot-matrix brush, the parameters are spindle speed 1000-5000rpm, feed rate 0.3-0.8mm; When the rib root is milled and removed, the parameters are cutting speed 80-120 mm / s, radial cutting width 0.4-2 mm, and feed per tooth 0.3-1 mm / z; When the mesh support impacts the root teeth for removal, the parameters are nominal pressure 25-100t and impact frequency 30-70 times / min.

4. The method for automatically removing support and grinding a skin sandwich workpiece according to claim 1, characterized in that: When monitoring the surface status online during the grinding process, a line laser measuring instrument is used to capture the surface contour dimensions of the product after support removal grinding, and compared with the theoretical profile of the blank to determine whether the area has completed support removal grinding, over-grinding or under-grinding.

5. The method for automatically removing support and grinding a skin sandwich workpiece according to claim 1, characterized in that: The robot arm includes a main robot arm and an end-cycle grinding device, wherein: The main robot arm includes: a first joint, a second joint and a third joint, the first joint rotates in the Z direction, the second joint rotates in the X direction, and the third joint rotates in the Y direction; The end-circulation grinding device is responsible for the feeding, rotation, and X- and Y-direction movement of the spindle during grinding; The X direction represents the long-range direction parallel to the work surface, the Y direction represents the short-range direction parallel to the work surface, and the Z direction represents the vertical direction perpendicular to the work surface.

6. The method for automatically removing support and grinding a skin sandwich workpiece according to claim 5, characterized in that: The end cycle grinding device includes: a spindle 3+1 motion mechanism, a line laser measuring instrument and an atomizing cooling device, wherein the spindle 3+1 motion mechanism includes a spindle, a pneumatic motor and a mechanical sensor; specifically: The spindle is installed at the end of the pneumatic motor through a floating unit and is driven to rotate by the pneumatic motor; the mechanical sensor is located at the rear end of the floating unit; The spindle 3+1 motion mechanism moves in the grinding area and realizes constant force floating grinding through pneumatic motors and mechanical sensors; the line laser measuring instrument is installed behind the spindle, and data is transmitted to the main control computer via a data cable; the mist cooling device is installed beside the spindle, and the tool is clamped on the spindle with a quick-change tool holder.

7. The method for automatically removing support and grinding a skin sandwich workpiece according to claim 6, characterized in that: When adjusting the support removal grinding parameters, the end cycle grinding device is used to achieve constant force floating grinding. The main control computer reduces the feed amount when it determines that the grinding is over-grinding based on the obtained data, and increases a cycle when it determines that the grinding is under-grinding.

8. The method for automatically removing support and grinding a skin sandwich workpiece according to claim 1, characterized in that: The planned sub-paths are as follows: Trial tool path: After path planning, the spindle executes the path with the same parameters as the formal path at a vertical height of 10-30mm from the overall contour of the blank, and only cycles once to verify the rationality of the path; Area n cyclic support removal sub-path: execute the cyclic support removal grinding path until the online monitoring surface state determines that the corresponding spatial path is completed; Tool change path: After completing the area n cycle to support, complete the spatial path required for tool change; When changing tools: the robot moves the spindle to the safe tool change point m, waits for the tool library to complete the retrieval and tool replacement, and then the robot moves the spindle to the positioning area n+1 cycle to support the starting point; Rapid positioning of sub-paths: After the spindle completes a path, it stops rotating, rises to the height of the test tool sub-path, and is then moved by the robotic arm to the spatial path corresponding to the next area with the shortest straight-line distance.

9. The method for automatically removing support and grinding a skin sandwich workpiece according to claim 1, characterized in that: Safe tool change point m: a point in the space outside the horizontal projection area after the additive blank is clamped and at the height of the test tool path, which does not interfere with the existing device. The spindle is moved to this point by the robot arm after completing the area n cycles to remove the support; Safe tool change point m': outside the horizontal projection area after the additive blank is clamped, at the height of the test tool path, ensuring that there is no interference with any device, and the spatial distance from the safe tool change point m is less than the tool change operation distance of the holding mechanism in the tool library. After completing the "area n cycle support removal", the tool library will move the new tool to this point.

10. The method for automatically removing support and grinding a skin sandwich workpiece according to claim 1, characterized in that: The support area to be removed is divided into K areas, and the area division is performed in the order of dot matrix, rib plate, and grid support.

Images