CN109365793B

CN109365793B - Automatic grinding and polishing process for titanium alloy annular casting

Info

Publication number: CN109365793B
Application number: CN201811241971.XA
Authority: CN
Inventors: 吴超群; 田亮
Original assignee: Wuhan University of Technology (WUT)
Current assignee: Wuhan University of Technology (WUT)
Priority date: 2018-10-24
Filing date: 2018-10-24
Publication date: 2020-01-24
Anticipated expiration: 2038-10-24
Also published as: CN109365793A

Abstract

The invention provides an automatic grinding and polishing process for a titanium alloy annular casting. The titanium alloy annular casting is positioned and clamped on the surface of the rotary workbench through a clamp; the grinding and polishing work of the titanium alloy annular casting is realized by clamping the motorized spindle by the robot to move according to a certain track, and the machining path is adjusted by matching with various sensors so as to adapt to the complex contour and shape difference of parts. Therefore, the automatic grinding and polishing system for the titanium alloy annular casting has a wide application prospect in the processing of the titanium alloy annular casting, and can improve the production efficiency and bring considerable benefits to enterprises.

Description

Automatic grinding and polishing process for titanium alloy annular casting

Technical Field

The invention relates to a grinding and polishing process, in particular to an automatic grinding and polishing process for a titanium alloy annular casting.

Background

With the advent of chinese manufacture 2025, industrial robots are increasingly used. In the aircraft industry, many parts are made of titanium alloy materials, and most of blanks are produced by casting. After the titanium alloy is cast, an oxide layer is formed on the surface of the titanium alloy, and fine cracks exist on the surface of a fillet of the titanium alloy, so that the titanium alloy is not beneficial to subsequent processing and use of a finished product. Therefore, after the casting is completed, the surface of the titanium alloy, especially the round corner of the titanium alloy casting, needs to be polished. And the grinding and polishing by adopting the robot can improve the processing efficiency, ensure the processing precision and reduce the grinding and polishing cost.

In the actual production of the prior titanium alloy annular casting grinding and polishing, manual grinding and polishing are adopted, and a large number of workers hold an angle grinder and an electric grinding gun to process. The grinding and polishing of the titanium alloy annular casting mainly has the following three problems: 1. the radial dimension of the titanium alloy annular casting is large and reaches more than 900mm, and a common machining center is difficult to clamp 2. the surface of the titanium alloy annular casting is complex in contour, has a plane, an arc surface, a fillet, an intersecting line and the like, and can be machined by a 6-axis machine tool. 3. The titanium alloy annular casting is used as a casting, the actual size and the appearance of the casting are different from the theoretical values on the drawing, and the setting of the machining track cannot be finished by off-line programming. In the system, the titanium alloy annular casting is placed on the large-diameter rotary workbench, and the titanium alloy annular casting is driven to transfer the part to be processed into the working range of a robot during each processing. The industrial robot is relatively mature in technology, has enough freedom degree, can reach all postures and positions within a certain range, achieves machining of all parts, can record all contour points in a manual teaching mode, and is simpler to operate compared with a machining center. Meanwhile, the automatic grinding and polishing process is quite stable compared with manual work, the whole process can be processed according to set process parameters, the grinding and polishing effect is attractive and consistent, and disordered textures generated by manual grinding and polishing can not exist. Therefore, the titanium alloy annular casting is ground and polished by using an automatic system, and the process becomes necessary.

Disclosure of Invention

The invention aims to provide an automatic grinding and polishing system which is applied to a titanium alloy annular casting and has high speed, high efficiency and high quality.

The technical scheme adopted by the invention is as follows:

an automatic grinding and polishing process for a titanium alloy annular casting is characterized by comprising the following steps

Step 1: opening the feeding door, and clamping the titanium alloy annular casting on the clamp;

step 2: and (3) size compensation of the workpiece to be processed: performing threshold compensation on circumferential and height errors generated when a part to be processed is clamped, and performing threshold compensation on errors generated by the processing size of the part to be processed;

and step 3: clamping a tool required to be used in the next processing on the electric spindle;

and 4, step 4: leaving the interior of the equipment and closing the feeding door;

and 5: the part of the titanium alloy annular casting needing to be processed is selected through a display screen, and the part comprises

Cleaning casting heads on the front side and the back side of the workpiece to be machined:

measuring the height of the plane of the root part of the dead head, cutting, roughly grinding and semi-accurately grinding;

polishing a workpiece to be processed: comprises polishing a round hole cavity, a side arc and a bowl-shaped inner arc surface of a workpiece to be processed,

polishing the circular hole cavity of the workpiece to be processed:

the electric main shaft clamps the C-type hard alloy rotary file or the B-type hard alloy rotary file to polish in a cooling liquid environment, the diameters of the C-type hard alloy rotary file or the B-type hard alloy rotary file are equal, the clamping lengths are equal, and the set tool coordinates are established at the center of the top end of a tool;

polishing the side arc of the workpiece to be processed:

selecting a tool material, designing a cooling system, selecting cooling liquid by combining the adopted tool and the processed material, and calculating the pressure and flow of the cooling liquid; then, wear compensation is carried out on the cutter through a force control system, and the feeding speed of the robot during polishing is controlled according to the material to be processed and the surface roughness;

polishing the bowl-shaped inner arc surface of the workpiece to be processed:

the robot is enabled to grind a trace on the surface of a workpiece when moving according to a specified path, and then the robot deviates a distance to the same direction every time the robot finishes the path, so that a smooth surface is obtained; finally, when the surface with a certain width is polished, the workpiece is rotated by a small radian, so that the oxide layer on the surface of the whole bowl-shaped workpiece can be removed;

polishing the inner and outer bowl-shaped inner cambered surfaces of the workpiece to be processed:

polishing the inner and outer bowl-shaped inner cambered surfaces of the titanium alloy annular casting through four steps of rough polishing, semi-fine polishing, fine polishing and grinding and polishing;

step 6: the robot drives the tail end tool to move to the position near the loading door, the next used cutter is prompted to a worker through the display screen, and the worker clicks a cutter replacing completion button on the display screen after replacing the cutter to confirm that the cutter is replaced;

and 7: the display screen transmits information of a part to be machined to the PLC, the PLC controls a servo motor of the rotary workbench to drive the rotary workbench, further drives the titanium alloy annular casting to rotate to a corresponding angle, the electric spindle is opened, and after the cutter rotates to a specified rotating speed, the robot drives the electric spindle to move along a preset track, so that the cutter cuts the corresponding part of the titanium alloy annular casting;

and 8: and after the machining is finished, stopping the electric spindle, gripping a tail end tool by the robot, retreating to a safety point, and finishing the machining process of the titanium alloy annular casting by the rotary worktable.

In the above automatic grinding and polishing process method for the titanium alloy annular casting, the step of compensating the size of the workpiece to be processed specifically includes performing threshold compensation on a circumferential error generated when the part to be processed is clamped and performing threshold compensation on a circumferential error generated when the part to be processed is clamped;

the specific method for performing threshold compensation on the circumferential error generated when the part to be machined is clamped comprises the following steps:

step 1, installing a force sensor at the tail end of a robot and installing a tool to be used on an ER chuck of an electric spindle of a tail end tool, controlling the robot to enable the tool to approach a circumferential reference, controlling the robot to perform stepping motion, stepping △ x each time until the force sensor monitors that the tool touches the circumferential reference, and recording a current coordinate value x _1 of the robot, wherein a theoretical coordinate value is x _ 0;

step 2: the formula for calculating the circumferential error is as follows: the control system controls the rotary table to shift by 180 × (x _1-x _0) ÷ (R × pi), and shifts the position of the circumferential reference by θ.

In the above automatic grinding and polishing process method for the titanium alloy annular casting, the step of cleaning the casting head on the front and back surfaces of the workpiece to be processed specifically comprises:

step 1: measuring the height of the riser root plane, moving the robot to a set height position h0 where the measuring device is located, keeping the height unchanged, measuring and calculating to obtain the heights of the riser root plane, which are respectively h1 and h2, and calculating a maximum value h;

step 2: the maximum height of a plane where the dead head is located is h, the cutting allowance is set to be delta h, the electric spindle and the cooling system are started, and the dead head is cut to be delta h allowance by adopting a cutting blade through the linear motion of a robot;

and step 3: rough grinding, namely performing layered grinding by using a rotary file, wherein the machining allowance is delta a _ p, the total cutting depth is delta h-delta a _ p, the diameter of a cutter is d, the cutting travel distance is L, the cutting depth of each layer is a _ p ═ d/2- √ (((d/2); (L/2); (delta h-delta a _ p)/a _ p), the initial point of the first row with a riser and the terminal point of the first row are determined, and the rough grinding machining is completed by taking the row spacing L as trajectory deviation;

and 4, step 4: and semi-fine grinding, continuously grinding the last residual delta a _ p, adjusting the line spacing of the feed to be L/6, performing track deviation by using the line spacing of L/6 in the same way, finishing machining the residual quantity once, and finishing cleaning the casting head of the titanium alloy casting.

In the above automatic grinding and polishing process method for the titanium alloy annular casting, the step of polishing the workpiece to be processed specifically comprises polishing a circular hole cavity of the workpiece to be processed, polishing a side arc of the workpiece to be processed, and polishing a bowl-shaped inner arc surface of the workpiece to be processed,

the polishing step of the circular hole cavity of the workpiece to be processed specifically comprises the following steps:

closing the electric main shaft and clamping the hard alloy rotary file to enable the cutter to extend into the round hole cavity to be close to the bottom plane and move to the upper part of the bottom plane;

starting a force control sensor, and acquiring real-time position coordinates of the bottom plane in four directions and real-time position coordinates of the cylindrical surface of the inner wall of the circular hole cavity in four directions through force feedback;

replacing the real-time position coordinates in four directions of the bottom plane with the position coordinates in four directions corresponding to the cylindrical surface of the inner wall of the circular hole cavity; replacing the position coordinates in four directions corresponding to the bottom plane with the real-time position coordinates in four directions of the cylindrical surface of the inner wall of the circular hole cavity;

starting the electric spindle, cooling liquid, and polishing the bottom plane according to the newly formed bottom plane boundary in a spiral track manner;

closing the electric main shaft, replacing the hard alloy rotary file, opening the electric main shaft again, cooling the liquid, and polishing the cylindrical surface of the inner wall of the circular hole cavity according to the newly formed cylindrical surface of the inner wall of the circular hole cavity along an annular path track;

the side arc polishing step of the workpiece to be processed specifically comprises the following steps:

step 1: selecting the model of a cutter, and selecting the model of a hard alloy rotary file according to the radius of a fillet of the circular arc to be polished;

step 2: segmenting the arc g0(x, y, z) into N segments;

and step 3: dividing each segment of circular arc into A, B, C control points and D control points, controlling a cutter to sequentially approach A, B, C control points and D control points on the circular arc segment by using a force control sensor through the robot, and respectively obtaining coordinates of A, B, C control points and coordinates of the D control points;

and 4, step 4: calculating an arc AB arc equation g1(x, y, z), an arc BC arc equation g2(x, y, z), an arc CD arc equation g3(x, y, z) with point A, B and arc segment radius R;

and 5: controlling the tool to grind along equations g1(x, y, z), g2(x, y, z) and g3(x, y, z) under the set grinding force through a force control sensor;

step 6: adjusting the posture of the robot to enable the axis of the cutter and the plane where the arc is located to form an angle theta;

and 7: selecting a feeding speed, controlling the feeding speed of the rotary file according to the beat requirement of the circular arc polishing and the polishing surface quality requirement, polishing the circular arc sections, and polishing the next circular arc section according to the methods of the steps 3 to 6 after polishing one circular arc section until the circular arc fillet polishing of the whole circular arc is completed;

the polishing step of the bowl-shaped inner arc surface of the workpiece to be processed specifically comprises the following steps;

step 1, dividing a bowl-shaped inner arc surface of a titanium alloy casting into a plurality of fan-shaped areas according to the warp direction, and selecting a first fan-shaped area as a polishing area;

step 2, adjusting the position of the robot to enable the cutter to be positioned right above a polishing starting point X0 of a first sector area on the surface of the workpiece;

step 3, the robot drives the cutter to approach the starting point to grind, a trace is ground on the surface of the workpiece along a preset path in the warp direction, and the workpiece returns to the starting point X0;

step 4, the robot carries the cutter to shift a distance delta X along the weft direction of the inner surface of the robot from a starting point X0 to a position right above a starting point X1 of a second path;

step 5, repeating the step 3, polishing the second path, and driving the cutter to return to the starting point X1 of the second path;

step 6, repeating the step 4 and the step 5 until the first sector area is polished;

step 7, rotating the workpiece by the radian of the first sector area, and polishing the second sector area according to the methods in the steps 2 to 6;

and 8, repeating the step 7 until the whole polishing process of the bowl-shaped inner arc surface of the annular titanium alloy casting is completed.

In the above automatic grinding and polishing process method for the titanium alloy annular casting, the polishing step of the workpiece to be processed specifically includes:

step 1: roughly polishing, namely selecting a flap wheel with small granularity, and grinding and polishing a workpiece repeatedly by low main shaft rotating speed, low feed speed and large contact force;

step 2: semi-fine polishing, namely selecting a flap wheel with medium granularity, high main shaft rotating speed, medium feed speed and medium contact force, and grinding and polishing a workpiece back and forth for multiple times;

and step 3: fine polishing, namely selecting a flap wheel with large granularity, high main shaft rotating speed, high feed speed and low contact force, and grinding and polishing a workpiece back and forth for multiple times;

and 4, step 4: grinding and polishing, wherein the grinding paste with ultrahigh granularity is selected to be matched with a wool felt wheel, the rotating speed of a main shaft is high, the feed speed is high, the contact force is low, and the workpiece is ground and polished back and forth for multiple times.

The invention has the following advantages: 1. the automatic grinding and polishing operation of the titanium alloy annular casting is realized. The robot is used for gripping the electric spindle to grind and polish, the action is flexible, and the robot can move in postures, angles and tracks which cannot be realized by various other machine tools. And theoretical analysis can be carried out according to the machining requirements, then the obtained optimal technological parameters are input into the system, and the grinding and polishing cutting depth, the feeding speed and the cutting speed are correspondingly modified by changing the track and the speed of the robot and the rotating speed of the electric spindle, so that the optimal technological machining is realized. The stable process and the processing efficiency can be ensured during processing, and the quality of the processed surface is far higher than that of manual grinding and polishing. Meanwhile, the machining process is stable, and no sudden change force exists, so that the service life of the cutter is prolonged. The grinding and polishing cost is saved. 2. The workpiece is clamped on the rotary workbench, and the rotary workbench can be rotated to a specified angle by the system according to the current position required to be machined, so that the machining part is positioned in the range convenient for the robot to machine. After the rotation is finished, the rotary worktable can be tightly braked by supplying air, so that the rotary worktable cannot rotate under the action of cutting force during machining, and the position of a workpiece is caused to deviate. 3. The water tank is used for receiving the waste scraps generated in the machining process and the cooling water used after the waste scraps are discharged into the cooling and scrap discharging machine, the cooling and scrap discharging machine can discharge the waste scraps out of the system, the waste scraps are periodically cleaned by workers, and the cooling water is filtered and then is pressurized again for use. The cooling liquid water pipe is arranged along the robot, and the water outlet is aligned to the position of the cutter, so that cooling water can be moved along with the robot and continuously supplied to the machining position. According to different processes, cooling liquid is sometimes required to be added or not required during processing, and the cooling liquid can be controlled by controlling the switch of the water pump of the cooling chip removal machine. 4. The robot is used for grinding and polishing, the positions of the profiles of the parts, which are different from the positions of drawings, can be manually taught and adjusted, the operation is convenient and fast, and the operability is greatly improved compared with the tool setting operation of a machine tool. 5. The whole system uses the dustcoat, prevents that dust and coolant liquid from spilling outside the system or splashing the robot side, and a plurality of sides of dustcoat are opened has the window simultaneously, has both improved the aesthetic property of equipment, is convenient for the operator to observe inside behavior again. The display screen is arranged on the outer cover through the cantilever, so that the appearance is attractive, and the operation is convenient. 6. The method comprises the following steps that the actual position of a machined part can be detected on line through a laser ranging sensor and a force control sensor in the machining process, and an industrial robot-based titanium alloy casting riser cutting process is used when a casting riser is cut; in the polishing process, a circular arc polishing method and a process for reducing the cost of a cutter are matched, namely a two-dimensional error compensation method for polishing the inner cavity of a circular hole of a titanium alloy casting, a size compensation method for polishing an annular part by a robot, and an online detection method for a polishing positioning point of a casting robot; a method and a process for polishing the bowl-shaped inner arc surface of an annular casting are used when the surface of a part is polished, and the method is a robot constant-force polishing method imitating a human hand. Therefore, the influence of clamping errors, casting size errors, casting shape errors and cutter size errors on the machining process is reduced, and the machining efficiency and the process quality are improved.

Drawings

Fig. 1 is an appearance schematic diagram of the present invention.

Fig. 2 is a schematic view of the internal structure of the present invention.

FIG. 3 is a schematic view of a separator plate according to the present invention.

Fig. 4 is a schematic view of a robotic end tool of the present invention.

FIG. 5a is a front clamping view of the present invention.

FIG. 5b is a schematic view of the reverse side clamp of the present invention.

Fig. 6 is an overall schematic view of the present invention.

FIG. 7 is a schematic view of the pin assembly of the present invention.

FIG. 8a is a schematic front view of the floating V-block assembly of the present invention.

FIG. 8b is a perspective view of the floating V-block assembly of the present invention.

Fig. 9 is a schematic view of the installation of the three-jaw chuck of the present invention.

FIG. 10 is a circumferential compensation schematic of the present invention.

Fig. 11 is a schematic diagram of the present invention.

FIG. 12 is a schematic diagram of a cylindrical surface grinding track according to the present invention.

FIG. 13 is a schematic view of the orientation of the tool shank during grinding in accordance with the present invention.

FIG. 14 is a schematic view of the bowl intrados burnishing of the present invention.

Detailed Description

For a better understanding of the present invention, reference is made to the following detailed description of the invention in conjunction with the accompanying drawings.

In the figure, 1-base, 2-outer cover, 3-step, 4-display screen, 5-robot, 6-electric main shaft, 7-cutter, 8-clamp, 9-water tank, 10-cooling liquid mounting rack, 11-cooling chip removal machine, 12-titanium alloy annular casting, 13-outer cover partition board, 14-robot outer cover, 15-force control sensor, 16-laser ranging sensor, 17-sensor mounting rack, 18-cooling liquid pipe, 19-electric main shaft mounting flange, 20-rotary worktable, 21-three-jaw chuck, 22-A floating V-shaped block assembly, 23-pin assembly, 24-three-jaw chuck flange, 25-pin base, 26-outer pin, 27-inner pin, 28-upper cover A, 29 lower cover, 30-V-shaped block, 31-guide column, 32-flange copper sleeve, 33-spring, 34-limiting block, 35-V block seat, 36-flat key, 37-B floating V-shaped block component, 38-B rotary file, 39-C rotary file, 40-round cavity, 41-warp and 42-weft.

First, a system structure adopted by the present invention is described.

The appearance schematic diagram shown in fig. 1 comprises a base 1, a cover 2, a step 3 and a display screen 4. The outer cover 2 is arranged on the base 1, and a plurality of surfaces are provided with observation windows for operators to observe the internal working conditions. The front is a feeding door, and after being pulled open, workers can go in and out of the outer cover 2 through the steps 3 to carry out operations such as feeding, blanking, tool changing and the like. The display screen 4 is arranged on the outer cover 2 in a hanging mode, and workers can interact with the system through the display screen 4 to input the part to be processed or monitor the running condition of equipment.

The internal structure as shown in fig. 2 comprises a base 1, an IRB6700-200/2.60 robot 5, an electric spindle 6, a cutter 7, a clamp 8, a water tank 9, a cooling chip remover 11 and a titanium alloy annular casting 12. The workman withdraws from the equipment with titanium alloy annular casting 12 clamping to anchor clamps 8 back, closes the material loading door on the dustcoat 2, inputs the position that needs processing and starting equipment, and then PLC can control anchor clamps 8 and rotate, changes titanium alloy annular casting 12 to predetermined angle so that the processing operation, rotates the swivel work head pneumatic brake air feed through to anchor clamps 8 after accomplishing and locks the mesa. Then, the PLC controls the electric spindle 6 indirectly fixed at the tail end of the IRB 6700-plus-200/2.60 robot 5 to rotate at a certain rotating speed according to a process recorded in advance, and after the electric spindle 6 starts to rotate and reaches a preset rotating speed, the IRB 6700-plus-200/2.60 robot 5 grasps the electric spindle 6 to move according to a set track, so that the cutter 7 cuts a part to be machined of the titanium alloy annular casting 12. The electric spindle 6 uses a special grinding electric spindle with a protection grade of IP67 or higher. After the part to be processed in a certain range is processed, if other parts need to be processed, the IRB 6700-plus-200/2.60 robot 5 retreats to the safe position, the PLC releases the pneumatic brake of the rotary worktable of the clamp 8, and the clamp 8 is rotated to the next angle so as to process the next part. The scrap waste produced during the machining and the used cooling liquid will fall onto the surface of the rotary table 7, after washing into the water tank 9 below the clamp 8. The water tank 9 is provided with a material leaking hole, and the waste scraps and the cooling liquid are discharged into the cooling chip remover 11. The cooling chip removal machine 11 will continuously convey the waste chips and waste materials out of the equipment, and the waste chips and waste materials are collected and cleaned by operators in a unified way, and meanwhile, the used cooling water is filtered for reuse.

The partition diagram shown in FIG. 3 includes an outer cover 2, an IRB6700-200/2.60 robot 5, an outer cover partition 13, and a robot outer cover 14. A housing partition 13 is mounted on the housing 2 to divide the interior space of the apparatus into two parts. A hole with a certain size is formed on the base plate, which is enough to ensure the movement space in the processing process of the IRB6700-200/2.60 robot 5. The robot coat 14 is made of waterproof cloth, a hole is formed in the middle of the robot coat, a rubber band is arranged in the hole, the IRB6700-200/2.60 robot 5 penetrates through the hole in the robot coat 14, and the hole is folded by the rubber band and is hooped on the arm of the IRB6700-200/2.60 robot 5. The outer edge of the outer robot sleeve 14 is fixed on the partition plate 13 through bolts, and the outer cover 2, the outer cover partition plate 13 and the outer robot sleeve 14 are matched for use, so that metal dust generated by cutting and splashed cutting liquid can be limited on the side of the titanium alloy annular casting 12, and pollution is avoided. Fig. 4 shows a schematic diagram of a robot end tool, which includes an electric spindle 6, a tool 7, a force control sensor 15, a laser ranging sensor 16, a sensor mounting bracket 17, a coolant pipe 18, an electric spindle flange 19, and a coolant pipe mounting bracket 10. The force control sensor 15 is arranged on a flange plate at the tail end of the IRB6700-200/2.60 robot 5, the electric spindle flange plate 19 is arranged on the other side of the force control sensor 15, and the force applied to an object connected with the side can be detected by the force control sensor 15. The electric spindle 6 and the sensor mounting frame 17 are mounted on an electric spindle flange, the laser ranging sensor 16 is mounted on the sensor mounting frame 17, and the cooling liquid pipe 18 is mounted on an electric spindle flange 19 through the cooling liquid pipe mounting frame 10. When the method is used, the electric spindle 6 is controlled by the PLC to drive the cutter 7 to reach a preset rotating speed, before cutting, the IRB 6700-plus-200/2.60 robot 5 can be used for driving a tail end tool to reach an appointed position, so that the laser sensor 16 is aligned to the surface of a part to be processed, distance data is measured, and on the basis, a high-speed and high-efficiency riser cutting method is used when a casting head is cut, and an online detection method of a casting robot grinding positioning point is used in the grinding process; the cutting force data can be obtained in real time through the force control sensor during cutting, the clamping error, the casting size and shape error and the influence of the cutter size error on the machining process are reduced on the basis of the cutting force data, and the machining efficiency and the process quality are improved.

As shown in fig. 5a, the front clamping schematic diagram and the back clamping schematic diagram of fig. 5b, mainly include a rotary table 1, a three-jaw chuck 2, a three-jaw chuck flange 5, floating V-shaped

block assemblies

3 and 19, a pin assembly 4, and a titanium alloy annular casting 18. The three-jaw chuck 2 is installed on the rotary workbench 1 through a three-jaw chuck flange 5, the floating V-shaped

block assemblies

3 and 19 and the pin assembly 4 are installed on the rotary workbench 1 through T-groove bolts and nuts, and the titanium alloy annular casting 18 is clamped on the clamp.

The overall schematic shown in fig. 6 may show three pin assemblies 4, a floating V-block assembly 3, B floating V-block assembly, with the three-jaw chuck 2 arranged on the rotary table 1. The three pin assemblies 4 are directly installed in a T-shaped groove of the rotary workbench 1 through T-groove bolts and nuts, the floating V-shaped block assembly A3 and the floating V-shaped block assembly B19 are firstly positioned in the T-shaped groove of the rotary workbench 1 through flat keys 17, the relative positions of the two floating V-shaped block assemblies and the rotary workbench 1 are guaranteed, and then the T-groove bolts and the nuts are used for locking. The three-jaw chuck 2 is arranged on the rotary worktable 1 through a three-jaw chuck flange 5, and the three parts are kept concentric through a positioning hole and a boss and locked with a nut through a T-shaped groove bolt.

As shown in the schematic diagram of the pin assembly of fig. 7, the present clip has three pin assemblies 4, each pin assembly 4 consisting of an outer pin 7, an inner pin 8 and a pin boss 6. The pin boss 6 is provided with a bolt hole for attachment to the rotary table 1, and is used for attaching the pin assembly 4 to the rotary table 1. Two fine thread threaded holes are formed in the pin block 6 and used for installing the outer pin 7 and the inner pin 8. When two pins are installed, attention needs to be paid to the fact that after the pins are installed in the pin bases 6, the distance between the pins and the surface of the rotary workbench 1 needs to be measured through a dial gauge, and the fact that the top ends of the three outer side pins 7 and the top ends of the three inner side pins 8 are equal to the surface of the rotary workbench 1 respectively is guaranteed. After the height is adjusted, the nut is screwed up for fixing.

As shown in fig. 8a and 8b, the floating V-

block assemblies

3 and 19 are substantially the same, and only the heights of the two V-blocks 11 are different, each floating V-block assembly 3 includes two upper covers 9, two lower covers 10, one V-block 11, two guide posts 12, two copper flange sleeves 13, two springs 14, a stopper 15, a V-block seat 16, and a flat key 17. The guide post 12 is mounted on the V-block mount 16 and is locked at the end with a nut. The spring 14 is sleeved outside the guide column 12, two mounting holes for mounting the flange copper sleeve 13 are formed in the V-shaped block 11, the flange copper sleeve 13 is in clearance fit with the guide column 12, and the flange copper sleeve is sleeved on the guide column 12 and can slide along the guide column 12. The limiting block 15 is mounted on the V-block seat 16 and limits the downward stroke of the V-shaped block 11 on the V-shaped block 11. The lower cover 10 is arranged on the V-shaped block 11 and moves up and down along with the V-shaped block 11, and the upper cover 9 is arranged at the tail end of the guide column 12 and does not move up and down along with the V-shaped block 11. The upper cover 9 and the lower cover 10 are both hollow cylinders with one closed end, and the inner aperture of the upper cover 9 is larger than the outer diameter of the lower cover 10. As the V-shaped block 11 moves upwards, the lower cover 10 will finally push against the upper cover 9, so that the V-shaped block 11 cannot move upwards any more, and the upward stroke of the V-shaped block 11 is limited. Meanwhile, in the stroke of the V-shaped block 11, the lowest end of the upper cover 9 is always higher than the highest end of the lower cover 19 to form a labyrinth, so that water and scraps are prevented from entering the position of the flange copper sleeve 13 and influencing the normal sliding of the flange copper sleeve 13 on the guide column 12. One side of the V-shaped block seat 16, which is in contact with the rotary workbench 1, is provided with a flat key groove, and the V-shaped block seat is arranged on a T-shaped groove of the rotary workbench 1 after being provided with a flat key 17, so that the direction of the floating V-shaped block assembly 3 is ensured to be right opposite to the circle center of the rotary workbench 1. When the titanium alloy annular casting 18 is clamped, the V-shaped block 11 is pressed down under the action of the gravity of the titanium alloy annular casting 18, but the pressure between the V-shaped block 11 and the titanium alloy annular casting 18 is ensured through the spring 14, and the centering and positioning effect of the V-shaped block 11 on the oval structure on the titanium alloy annular casting 18 is ensured.

The three-jaw chuck installation schematic diagram shown in fig. 9 comprises a rotary table 1, a three-jaw chuck 2 and a three-jaw chuck flange 5. The end face of the three-jaw chuck 2 is provided with a spigot which is matched with a circular boss on the upper surface of the three-jaw chuck flange 5 to ensure that the three-jaw chuck 2 and the three-jaw chuck flange 5 are coaxial. The center of the rotary worktable 1 is provided with a positioning hole which is matched with a circular boss on the lower surface of the three-jaw chuck flange 5 to ensure the coaxiality between the rotary worktable 1 and the three-jaw chuck flange 5. To this end, the rotary table 1 is coaxial with the three-jaw chuck 2. The three are fixed by bolts and nuts.

The system mainly comprises the following creation points:

1. the electric main shaft is arranged on a six-shaft flange of the industrial robot, and a cutter is arranged at the tail end of the electric main shaft and can be driven by the robot to do fixed-orbit motion. The rotating speed of the electric spindle can be adjusted by a PLC controlled frequency converter, and the moving speed of the robot can also be adjusted, so that the requirements on technological parameters required by different processing technologies can be met. 2. The fixture of the titanium alloy annular casting is arranged on the surface of the rotary workbench, the rotary workbench is driven by the servo motor after the titanium alloy annular casting is clamped, when the robot processes a certain part of the titanium alloy annular casting, a signal can be sent to the PLC, the titanium alloy annular casting is rotated to a position to be processed to be in a specified angle within the working range of the robot, and subsequent processing is convenient to implement. 3. A bowl-shaped water tank is arranged below the rotary workbench, and both the waste scraps generated in the machining process and the cooling water used in the machining process can be concentrated at the bottom of the water tank and flow into the cooling and chip removing machine through an opening in the bottom of the water tank. The cooling chip removal machine can continuously discharge the waste chip waste, and the cooling water is filtered and then is reused. The water pipe of cooling water is arranged along the robot arm, the cooling water nozzle is arranged near the electric spindle and aligned to the head of the cutter, and the PLC controls the switch of the water pump of the cooling chip removal machine to turn on or off the cooling water, so that the requirements of different processes on the cooling water are met. 4. The display screen is mainly used for monitoring the real-time condition of the system work, and the information of the current processing position, the current processing technological parameters, the processed time, the processed number of pieces and the like can be checked through the display screen. Meanwhile, the operation mode can be selected by the operator, and the processing part can be appointed. 5. The outer cover is used for preventing water and dust from splashing. The outer cover is provided with a feeding door, and a worker can open the feeding door to perform feeding and discharging operations. The feeding door is provided with a travel switch, and the system cannot be started when the feeding door is not closed. When the system works, the material loading door is opened, and the emergency stop is also triggered. Be equipped with the baffle in the dustcoat, keep apart robot and swivel work head in two regions, it has the hole to open on the baffle, and enough robot arm stretches out and carries out the processing of required scope. The robot arm is sleeved with a robot waterproof jacket, the robot moves along with the robot, and the edge of the jacket is fixed on a robot partition plate to play a role in preventing water and dust from splashing into the side of the robot. 6. The electric spindle can be provided with a plurality of cutters. The electric spindle can realize a cutting function when being provided with the grinding wheel, can realize a processing function when being provided with the rotary file and the grinding head, can realize a polishing function when being provided with the blade wheel and the wool felt, and can adapt to the processing requirements of different parts of the titanium alloy annular casting. Meanwhile, a force control sensor and a laser ranging sensor are additionally arranged on the robot, and a titanium alloy casting riser head cutting process based on an industrial robot is used when a casting head is cut; in the polishing process, a circular arc polishing method and a process for reducing the cost of a cutter are matched, namely a two-dimensional error compensation method for polishing the inner cavity of a circular hole of a titanium alloy casting, a size compensation method for polishing an annular part by a robot, and an online detection method for a polishing positioning point of a casting robot; a method and a process for polishing the bowl-shaped inner arc surface of an annular casting are used when the surface of a part is polished, and the method is a robot constant-force polishing method imitating a human hand.

Secondly, the following is a specific operation method of the above system structure.

As shown in the schematic front clamping diagram of fig. 5a, during front clamping, the upper surface of the titanium alloy annular casting 12 is upward, the titanium alloy annular casting 12 is moved to a position above the fixture, the inner hole of the titanium alloy annular casting 12 is approximately aligned with the center of the three-jaw chuck 21, the titanium alloy annular casting 12 is rotated around the center of the circle until the coarsest elliptical structure of the titanium alloy annular casting is approximately aligned with the V-shaped groove of the floating V-shaped block assembly 22, and then the titanium alloy annular casting 12 is slowly dropped. After falling, the three outer side pins 26 are not in contact with the annular titanium alloy casting 12, the three inner side pins 27 are in contact with the annular belt-shaped end surface of the lower surface of the annular titanium alloy casting 12, and the three points are in contact to form a plane, so that the linear freedom degree and the two rotational freedom degrees of the annular titanium alloy casting 12 in the height direction are limited. The oval structure of the titanium alloy annular casting 12 is clamped into an A floating V-shaped block assembly 22 and the V-shaped block 30 of the titanium alloy annular casting is pressed down, the A floating V-shaped block assembly 22 can quickly realize centering and positioning of the oval structure, the freedom degree of the titanium alloy annular casting 12 in the height direction cannot be limited due to the fact that the A floating V-shaped block assembly 22 can float up and down, the B floating V-shaped block assembly 37 is not in contact with the titanium alloy annular casting, and therefore the circumferential rotation freedom degree of the titanium alloy annular casting 12 is limited. After the placement is finished, the three-jaw chuck 21 is unscrewed, so that the clamping jaws of the three-jaw chuck are opened to prop against the inner circular hole of the titanium alloy annular casting 12, the horizontal linear freedom degree of the titanium alloy annular casting 12 is limited, and a clamping force is provided. To this end, the titanium alloy annular casting 12 is fully positioned and clamped.

When the reverse side is clamped, the three inner side pins 27 are not in contact with the titanium alloy annular casting, the three outer side pins 26 are in contact with the titanium alloy, the floating V-shaped block assembly 22A is not in contact with the titanium alloy annular casting 12, the floating V-shaped block assembly 37B is in contact with the titanium alloy annular casting 12, and the clamping principle is the same as that when the front side is clamped.

If the titanium alloy annular casting 12 needs to be rotated, the rotation of the titanium alloy annular casting 12 can be controlled by controlling a servo motor arranged in the rotary worktable 20, so that the titanium alloy annular casting 12 is driven to rotate to a specified angle.

If the titanium alloy annular casting 12 needs to be detached, the three-jaw chuck 21 is screwed to close the clamping jaws, and then the titanium alloy annular casting 12 moves upwards to leave the V-shaped groove of the floating V-shaped

block assembly

3 or 19, so that the titanium alloy annular casting can move freely.

The preferred embodiment of the step of compensating the dimension of the workpiece to be machined used in the present invention comprises the steps of:

step 1: when a part is clamped, the inner ring reference surface of the annular part is clamped through the three-jaw chuck, and the central axis of the part is positioned through the three-jaw chuck, so that the centering of the part is realized;

step 2, performing threshold compensation on the circumferential error generated when the part to be processed is clamped, as shown in fig. 4, installing a force sensor at the tail end of the robot, collecting the grinding pressure of a tool at the tail end of the robot by the force sensor and controlling the size of the grinding pressure, a cutter is arranged on an ER chuck of an electric spindle of a tail end tool, so that the robot controls the cutter to be close to the circumferential reference surface of a part according to the feeding amount of 0.05 mm/time, when the cutter contacts the circumferential reference surface of the part, the grinding pressure value acquired by the force sensor can be increased from 0, the robot is stopped after the force sensor detects the increasing edge of the force, and the current cutter coordinate point is recorded and transmitted to the control system, the control system obtains the circumferential error value of the part by comparing and calculating with the theoretical value, and the zero position of the rotary worktable is controlled to compensate, so that the circumferential reference surface rotates to a theoretical position. The specific implementation principle is as shown in fig. 10, a tool is fed from x0 to one side step by step until a force sensor detects that the tool touches a part, a current position x1 is recorded, and as the diameter of the annular part is large and the clamping error of the part is small, the value of (x _1-x _0) is approximately equal to the arc length of circumferential offset, the circumferential error after clamping the part can be calculated by a formula theta of 180 x (x _1-x _0) ÷ (R × pi), and then a control system controls a rotating table to compensate the corresponding angle value to compensate the circumferential clamping error of the annular part when rotating;

and 3, performing threshold value compensation on the height error generated when the part to be machined is clamped, and when the upper surface is polished, because the size of the upper surface of the part has deviation due to the clamping error of the part and the casting error of the part, measuring the part to be polished and compensating the size error before polishing. The compensation method comprises the following steps: as shown in fig. 4, the other side of the electric spindle mounted on the robot end tool is mounted with a laser distance sensor for measuring the distance between the upper surface of the part and the sensor to determine the height error of the part to be polished on the upper surface of the part, then the height compensation value is calculated by the control system according to the measurement result, and the coordinates of the tool setting point of the robot are fed back and controlled to enable the tool to reach the upper surface of the part, so that the part is not polished or polished excessively, and the size compensation of the upper surface of the part is achieved;

the invention discloses a cleaning process of a casting head of a titanium alloy annular casting, which comprises the following specific process steps

Step 1: firstly, a titanium alloy annular casting is clamped on a clamp, a CBN cutting blade is arranged at the tail end of an electric main shaft, the granularity of the cutting blade is 60, the concentration of the cutting blade is 100 percent, the hardness is M grade, the diameter is 150mm, the width of an abrasive material with the inner diameter of 25.4mm is 5mm, and the thickness is 1mm

Step 2: the robot is moved, the posture of the robot is adjusted to a measuring posture, three points of a plane where the laser distance sensor is arranged for measuring the riser are opened, the error of the plane where the riser is arranged is large due to poor casting consistency, the normal direction of the plane is found through the distance sensor and fed back to the robot, and therefore the posture of a cutting piece is adjusted to be consistent with the normal direction of the plane, the error is adjusted to cut, and the consistency of the height of the riser after cutting is guaranteed.

And step 3: opening a cooling liquid, wherein the titanium alloy belongs to a difficult-to-process material, and has the defects of large grinding force, high grinding temperature, serious adhesion of a grinding wheel, easy surface burn and large residual stress in the processing process, so that the special environment-friendly cutting liquid for grinding the titanium alloy is required, and comprises 2% of tricarboxylate, 12% of triethanolamine, 3% of glycerol, 0.2% of organosilicon, 3% of oleic acid, 0.3% of benzotriazole derivatives and the balance of water; in the polishing process, high-pressure double-pipe jet flow is adopted, the pressure is 0.7Mpa, and the flow is not lower than 10L/min; the cooling liquid pipe is arranged on the electric spindle and moves along with the movement of the electric spindle, the spraying direction of the cooling liquid is tangent to the cutting direction of the cutting blade and is aligned to two sides of the casting head, and therefore the cooling liquid can enter the casting head to achieve a better cooling effect in the cutting process.

And 4, step 4: the dead head is cut to 1mm of allowance by adopting a resin CBN cutting piece through the linear motion of a robot, the contact arc length at the initial stage and the later stage of cutting is short, the grinding temperature is low due to small grinding force, the feed speed can be increased to 0.2mm/s, the contact arc length is long at the middle stage of cutting, the grinding force is large, the grinding temperature is high, the feed speed needs to be reduced to 0.1mm/s, and the rotating speed of a main shaft is 6000 r/min.

And 5: the cutting blade at the tail end of the electric spindle is replaced by a hard alloy spherical rotary file with the diameter of 16mm

Step 6: coarse grinding, namely cutting to the residual 1mm, then performing layered grinding by using a rotary file, wherein the total feed depth is 0.9mm, feeding is performed in three layers, the feed depth is 0.3mm each time, the feed speed is 3mm/s, the line spacing is 3mm, and the rotating speed of a main shaft is 10000 r/min;

and 7: semi-finish grinding, namely, adopting a hard alloy ball-shaped rotary file pair with the diameter of 16mm to finish the grinding by 0.1mm, wherein the row spacing value is smaller to 0.5mm due to higher requirement on the roughness of the semi-finish grinding surface, the feed speed is 5mm/s, and the rotating speed of a main shaft is 10000 r/min;

and (5) repeating the steps 1-7 until all the casting heads are cleaned, and then cleaning the whole casting head of the titanium alloy annular casting.

The plane of the casting head after cutting and polishing is observed after the steps are completed, the surface is free of burn, the height of the stub is parallel and level to the plane of the bottom, and the surface roughness is measured to be 0.4um by adopting a roughness meter, so that the processing technology requirement is met.

The round hole cavity polishing method used in the invention comprises the following steps:

as shown in the grinding schematic diagram of fig. 11, when the bottom plane of the circular hole cavity 40 is ground, the B-type rotary file 38 is used, and in a state that the motorized spindle 6 is not opened, the robot drives the B-type rotary file 38 to move towards the bottom plane of the circular hole cavity 40, the force control sensor 15 is opened, the force control sensor 15 gives a signal after being contacted, the robot automatically reads the coordinates of the point, and the coordinates of the point A, B, C, D are respectively obtained in four directions of the top, the left, the bottom and the right of the plane; then the robot continues to drive the B-shaped rotary file 38 to move towards the cylindrical surface of the circular hole cavity 40, the force control sensor 15 is started, the force control sensor 15 gives a signal after contacting, the robot automatically reads the coordinates of the point, the coordinates of a point E, F, G, H are respectively obtained in four directions of the upper left, the lower right and the right of the cylindrical surface, the coordinate directions are calculated and adjusted through a process sequence, the coordinate directions are as shown in figure 12, the X values of the points E, F, G and H are respectively replaced by the X values of the points A, B, C and D, the Y values and Z values of the points A and D are respectively replaced by the Y and Z values of the points E and E, the Y and Z values of the points B and B are respectively replaced by the Y and Z values of the points F and C, and the Y and Z values of the points D and H, so that the Y and Z directions of the points A, B, C and D are accurately compensated, the X direction of the H point is also accurately compensated. Firstly, the bottom plane of the round hole cavity 40 is processed, the diameter of the B-type rotary file 38 is 10mm, the rotating speed of the electric spindle 6 is 8000r/min, the flow of the cooling liquid is 10L/min, the plane is polished according to a round track formed by the current coordinates of the points A, B, C and D, then the offset points of the points A, B, C and D, the coordinates of the points A, B, C and D are not changed along the direction of the circle center, and then the round path of the points A, B, C and D is shifted by 5mm is followed until the whole plane is polished. And after the first grinding is finished, increasing the X coordinate values of the points A, B, C and D by 0.1mm, grinding again according to the offset path for four times, and grinding the points A, B, C and D until the theoretical cutting amount is 0.3 mm. At this point, the polishing of the bottom plane of the circular bore 40 is completed.

As shown in the schematic diagram of the polishing track of the cylindrical surface shown in fig. 12, the diameter of the C-shaped rotary file 39 is 10mm, the tool coordinate of the C-shaped rotary file 39 is the same as that of the B-shaped rotary file 38, the rotating speed of the electric spindle 6 is 8000r/min, the flow rate of the cooling liquid is 10L/min, and then the circular arc track formed by the current points E, F, G, and H is used for polishing. After polishing is completed once, the coordinates of the point E, F, G, H are respectively shifted to the direction far away from the circle center by 0.1mm, a new polishing track is generated by using the new coordinates of the point E, F, G, H for polishing, the process is repeated for three times, the polishing is performed for four times in total, and the theoretical cutting amount is 0.3 mm. And finishing polishing the cylindrical surface around the circular hole cavity.

As shown in fig. 13, the circular arc grinding method used in the present invention includes the following steps:

step 1: selecting the type of a hard alloy rotary file with a proper size according to the radius of a fillet of an arc to be polished, for example, polishing a long circular arc with the radius of 8mm by using a hard alloy rotary file with the type D12;

step 2: segmenting the arc segment to be polished, polishing one segment at every 60 degrees, and rotating the workbench by 60 degrees to polish the next arc segment after polishing;

and step 3: using a force control sensor to control the cutter to step towards the center of the circular arc at a position higher than the position to be polished at 0 degree of the circular arc section until the cutter is detected to contact the side surface of an inner tangent cylinder of the circular arc, then enabling the cutter to step towards the fillet to be polished in the vertical direction (the axial direction of the circular arc or the inner tangent cylinder 44) until the cutter is detected to be close to the fillet of the circular arc in the vertical direction, recording the current coordinate point A, sequentially repeating the step 2 at 20 degrees, 40 degrees and 60 degrees, and respectively obtaining a coordinate point B, C, D;

and 4, step 4: the arc polishing path is re-planned by the A, B, C, D four coordinate points and the radius of the arc segment, so that the actual polishing path is more accurate;

and 5: calculating the optimal flow and pressure of the cooling liquid (the spraying pressure of the cooling liquid is 0.5-0.9Mpa, the flow is not lower than 10L/min) when the titanium alloy is polished, adjusting the flow and pressure of the cooling liquid by adjusting a throttle valve and an overflow valve of a cooling system, adjusting the flow direction of the cooling liquid by adjusting a bamboo joint pipe, and spraying the cooling liquid to the front and the rear of the cutter during cutting; during polishing, the cutting temperature can be reduced through cooling liquid, chips are taken away, titanium alloy burn is prevented, and the abrasion speed of the cutter during polishing is reduced;

step 6: when the tool is controlled to polish, the component force of the polishing force in the circular arc centripetal direction is 15-20N, and the component force in the downward direction (namely the circular arc axis faces the fillet direction) is 15-20N, so that the hard alloy rotary file is always attached to the circular arc to be polished, the tool can be prevented from shaking, the tool abrasion can be reduced, the tool can be continuously machined by compensating the tool abrasion by controlling the output pressure of the force control sensor after the tool is slightly abraded, and the traditional method of polishing by adopting an absolute track cannot compensate the tool in real time; as shown in the fourth figure, the posture of the robot is adjusted to enable the axis of the cutter and the plane where the arc is located to form an angle of 15 degrees, so that the cutter is always polished by the cutting edge with the maximum diameter, the service life of the cutter is prolonged, and the polishing efficiency is improved; and controlling the cutter to polish along the polishing path, wherein the feeding speed is 3-5 mm/s.

As shown in fig. 14, the bowl-shaped intrados grinding method used in the present invention includes the following steps:

1. finishing the construction of a robot system for polishing the bowl-shaped inner cambered surface of the annular casting;

2. dividing the inner surface of the bowl-shaped titanium alloy casting into a plurality of fan-shaped areas according to the direction of the meridian line 41, and selecting a first fan-shaped area as a polishing area;

2. opening the electric spindle 6, rotating at 3000r/min, and setting the pressure value of the force control sensor 15 of the robot 5 to 15N;

3. adjusting the position of the robot 5 to enable the cutter 7 to be located 3mm above a polishing starting point X0 of a first fan-shaped area on the surface of the titanium alloy annular casting 12; the robot 2 brings the cutter 7 close to the starting point, and grinds a trace on the surface of the workpiece 8 along a preset path in the direction of the meridian line 41 and returns to the starting point X0; the robot 2 carries the cutter 7 to shift a distance delta X along the direction of the inner surface weft 42 from the starting point X0 to reach a position 3mm right above the starting point X1 of the second path; after each polishing, the polishing platform deviates a small short distance of 0.5mm towards the same direction until the total deviation X reaches 1/72 of the whole bowl-shaped perimeter, namely, the polishing of the first sector area is completed; the electric main shaft 6 is lifted to an upper safe position through the robot 2, and the rotary worktable is rotated to enable the bowl-shaped inner arc surface of the titanium alloy annular casting to rotate for 5 degrees;

4, repeating the process 3 until the whole titanium alloy annular casting is punched to form a bowl-shaped inner arc surface.

The method for polishing the bowl-shaped inner cambered surface used in the invention comprises the following steps

1. Firstly, finishing the construction of a bowl-shaped inner cambered surface polishing system of the titanium alloy annular casting;

2. programming a polishing track of the bowl-shaped inner arc surface of the titanium alloy annular casting to be led into a six-axis robot, opening a force control sensor, and performing constant-force polishing in a force-position control mode, wherein the force is variable and can be set according to the surface roughness and polishing amount of a workpiece, and the direction of the force is always kept consistent with the normal direction of the bowl-shaped inner arc surface of the titanium alloy annular casting;

3. rough polishing: replacing a flap wheel with the granularity of 80 and the diameter of 40mm on an ER chuck at the tail end of an extension rod, grinding and polishing 10 times back and forth, wherein the rotating speed of a main shaft is 6000r/min, the feed speed is 15mm/s, the contact force is 16N;

4. semi-fine polishing, replacing an ER chuck at the tail end of an extension rod with a flap wheel with the granularity of 240 and the diameter of 40mm, grinding and polishing 10 times back and forth, wherein the rotating speed of a main shaft is 8000r/min, the feed speed is 20mm/s, the contact force is 12N;

5. fine polishing, namely replacing an ER chuck at the tail end of an extension rod with a flap wheel with the granularity of 400 and the diameter of 40mm, grinding and polishing 10 times back and forth, wherein the rotating speed of a main shaft is 8000r/min, the feed speed is 25mm/s, and the contact force is 8N;

6. grinding and polishing, replacing an ER chuck at the tail end of the extension rod with grinding paste with the granularity of 1000 and matching with a wool felt wheel with the diameter of 40mm, wherein the rotating speed of a main shaft is 8000r/min, the feed speed is 25mm/s, the contact force is 8N, and grinding and polishing are carried out for 10 times.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Although more than 1-base, 2-housing, 3-step, 4-display, 5-robot, 6-motorized spindle, 7-tool, 8-clamp, 9-water tank, 10-coolant mount, 11-cooled chip ejector, 12-titanium alloy annular casting, 13-housing spacer, 14-robot housing, 15-force control sensor, 16-laser range sensor, 17-sensor mount, 18-coolant tube, 19-motorized spindle mounting flange, 20-rotary table, 21-three-jaw chuck, 22-A floating V-block assembly, 23-pin assembly, 24-three-jaw chuck flange, 25-pin seat, 26-outboard pin, 27-inboard pin, 28-upper housing A, 29 lower cover, 30-V-shaped block, 31-guide column, 32-flange copper sleeve, 33-spring, 34-limiting block, 35-V block seat, 36-flat key, 37-B floating V-shaped block component, 38-B rotary file, 39-C rotary file, 40-round cavity, 41-warp and 42-weft. Etc., but does not exclude the possibility of using other terms. These terms are used merely to more conveniently describe and explain the nature of the present invention; they are to be construed as being without limitation to any additional limitations that may be imposed by the spirit of the present invention.

Claims

1. An automatic grinding and polishing process for a titanium alloy annular casting is characterized by comprising the following steps

step 2: and (3) size compensation of the workpiece to be processed: performing threshold value compensation on circumferential and height errors generated when a part to be processed is clamped;

polishing a workpiece to be processed:

comprises polishing a round hole cavity, a side arc and a bowl-shaped inner arc surface of a workpiece to be processed,

polishing the circular hole cavity of the workpiece to be processed:

polishing the side arc of the workpiece to be processed:

selecting a tool material, designing a cooling system, selecting cooling liquid by combining the adopted tool and the processed material, and calculating the pressure and flow of the cooling liquid; then the tool is compensated for wear by a force control system, and the feed rate of the robot during grinding is controlled according to the material to be processed and the surface roughness

Polishing the bowl-shaped inner arc surface of the workpiece to be processed:

polishing a workpiece to be processed:

polishing the bowl-shaped inner cambered surface of the titanium alloy annular casting through four steps of rough polishing, semi-fine polishing, fine polishing and grinding and polishing;

and 8: after the machining is finished, stopping the electric spindle, enabling the robot to grip a tail end tool and retreat to a safe point, and ending the machining process of the titanium alloy annular casting by returning the rotary worktable to zero;

the size compensation step of the workpiece to be processed specifically comprises the steps of performing threshold compensation on a circumferential error generated when the part to be processed is clamped and performing threshold compensation on a height error generated when the part to be processed is clamped;

step 1: the method comprises the steps that a force sensor is installed at the tail end of a robot, a tool needed to be used is installed on an ER chuck of an electric spindle of a tail end tool, the robot is controlled to move the tool to a circumferential reference accessory, the force control sensor is opened, the direction of the force is set to be vertical to a reference plane, the tool automatically approaches to the circumferential reference, when the force sensor detects that the force reaches a set value, the tool slides along the reference plane, the sliding length is L, and end point coordinates (x _1, y _1, z _1) are read, wherein x is the direction of the circumferential reference, y is the direction vertical to the circumferential reference direction in a horizontal plane, and z is the vertical direction, namely the coordinate value of the tail end of the robot; the circumferential reference theoretical coordinate value is x _0, namely the coordinate value of the tail end of the robot when the cutter touches the circumferential reference under the theoretical condition;

step 2: the formula for calculating the circumferential error is as follows: θ is 180 × (x _1-x _0) ÷ (R × pi), i.e., the circumferential compensation threshold θ, which is also the circumferential center angle error value; the rotating workbench is controlled to shift through the control system, so that the position of the circumferential reference shifts by theta, and R is the distance from the position of the circumferential reference of the part to the center of a circle;

the specific method for performing threshold compensation on the height error generated when the part to be processed is clamped comprises the following steps:

adjusting the robot posture to a height measurement posture to enable laser irradiated by the laser distance sensor to be perpendicular to a plane to be processed, and measuring the distance h between the upper surface of the part and the sensor through the laser distance sensor on the tail end tool before polishing₁And feeding back the measurement result to the control system and the standard distance value h₀The height error △ h is obtained by calculation₁-h₀Namely, the height compensation threshold value △ h controls the robot to deviate △ h in the height direction during grinding;

the polishing step of the workpiece to be processed comprises the polishing of a round hole cavity of the workpiece to be processed, the polishing of a side arc of the workpiece to be processed and the polishing of a bowl-shaped inner arc surface of the workpiece to be processed,

step 2: segmenting the arc g0(x, y, z) into N segments;

step 1, dividing the inner surface of a bowl-shaped titanium alloy casting into a plurality of fan-shaped areas according to the warp direction, and selecting a first fan-shaped area as a polishing area;

and 8, repeating the step 7 until the polishing of the oxide removal layer on the inner surface of the whole bowl-shaped titanium alloy casting is finished.

2. The automatic grinding and polishing process for the annular titanium alloy casting according to claim 1, wherein the step of cleaning the casting head on the front side and the back side of the workpiece to be machined specifically comprises the following steps:

3. The automatic grinding and polishing process for the annular titanium alloy casting, according to claim 1, is characterized in that the polishing step of the workpiece to be machined specifically comprises the following steps:

and step 3: fine polishing, selecting a flap wheel with large granularity, high main shaft rotating speed, high feed speed and low contact force,

grinding and polishing the workpiece back and forth for multiple times;