CN113829135A - Time-controlled grinding method, system and medium for optical element - Google Patents
Time-controlled grinding method, system and medium for optical element Download PDFInfo
- Publication number
- CN113829135A CN113829135A CN202111227785.2A CN202111227785A CN113829135A CN 113829135 A CN113829135 A CN 113829135A CN 202111227785 A CN202111227785 A CN 202111227785A CN 113829135 A CN113829135 A CN 113829135A
- Authority
- CN
- China
- Prior art keywords
- time
- controlled grinding
- grinding
- controlled
- workpiece
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B1/00—Processes of grinding or polishing; Use of auxiliary equipment in connection with such processes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B13/00—Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor
- B24B13/01—Specific tools, e.g. bowl-like; Production, dressing or fastening of these tools
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B21/00—Machines or devices using grinding or polishing belts; Accessories therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B21/00—Machines or devices using grinding or polishing belts; Accessories therefor
- B24B21/18—Accessories
Abstract
The invention discloses a time-controlled grinding method, a time-controlled grinding system and a time-controlled grinding medium for optical elements, wherein the method comprises the following steps: measuring initial surface shape error data of an optical element to be processed; configuring a time-controlled grinding machining head in the time-controlled grinding machining device according to the amplitude-frequency analysis result of the initial surface shape error data; selecting proper time-controlled grinding parameters according to the precision requirement of the workpiece; processing the sample by using the selected time-controlled grinding processing parameters, wherein the time-controlled grinding processing head is in orthogonal contact with the surface of the sample in the processing process, the constant-speed updating of the coated abrasive belt is kept, and a time-controlled grinding removal function is obtained; using a time-controlled grinding removal function to perform simulation processing and repeating the steps until the precision requirement is met; and the time-controlled grinding device is used for actually processing the workpiece according to the time-controlled grinding parameters when the precision requirement is met. Compared with the existing deterministic polishing method, the method greatly improves the processing efficiency on the basis of ensuring the accuracy of the optical element to be converged.
Description
Technical Field
The invention relates to the field of optical element processing, in particular to a time-controlled grinding processing method, a time-controlled grinding processing system and a time-controlled grinding processing medium for an optical element.
Background
The development in the fields of aerospace, astronomical exploration, military, energy, medical treatment and the like puts higher demands on the requirements of large-caliber optical elements. According to Rayleigh criterion, when the wavelength is unchanged, the larger diameter of the lens can effectively improve the resolution of the optical system, and meanwhile, the larger caliber can realize larger light incoming amount, thereby being beneficial to high-image-quality imaging. The caliber of a primary mirror of the lifted Hubo space telescope in 1990 reaches 2.4 meters; the aperture of a main mirror of an American keyhole-12 reconnaissance satellite reaches 3 meters, and the ground resolution can reach 0.1 meter; the aperture of the single mirror of the giant-scale hucho telescope (GMT) which is being constructed reaches 8.4 meters. In addition to the ever increasing diameter, the demand for large aperture optical elements is also increasing. Such as National Ignition (NIF) in the united states, where 7440 pieces of large-caliber precision optical elements are required in total; a European Extra Large Telescope (EELT) uses 798 mirrors with a 1.4m aperture, and so on. Therefore, the development in the above field has made demands for manufacturing equipment for large-diameter optical elements with high precision and high efficiency.
At present, the material of the large-aperture optical element represented by the hard and brittle materials such as fused quartz, silicon carbide, monocrystalline silicon and the like generally comprises the processes of grinding, shape-modifying polishing, film coating and the like. The grinding process utilizes a grinding machine to grind the lens, and as the grinding machine follows the restriction of the 'mother principle' of the traditional mechanical processing, the forming precision of the grinding machine is influenced by the self motion precision of the machine tool, so that the surface shape precision of the large-caliber lens is near 5 mu m PV. The finishing and polishing process after grinding mainly comprises computer-controlled optical forming technology (CCOS), including magnetorheological polishing, double-rotor small grinding head polishing, air bag polishing and the like, and can achieve surface shape precision of lambda/20 PV (lambda is 632.8nm) and surface roughness superior to Ra 1 nm. However, the polishing process described above generally exhibits low processing efficiencyAnd (5) problems are solved. Taking magnetorheological polishing as an example, the material removal efficiency is about 1.25 × 108μm3The correction of the surface shape error of 5 μm after grinding with a size of 500mm × 500 mm/min requires 1 week of operation, and the subsequent polishing requires a longer time if the lens diameter becomes larger. Problems associated with long polishing times include increased labor and time costs, higher failure probability of long-term working equipment, lower productivity, and the like. Although the material removal efficiency of the existing various grinding processes is high, the time linearity and the long-term stability of a removal function (a material removal distribution matrix in unit time) and the dimensional stability of the removal function cannot be guaranteed, so that the material removal efficiency cannot be used for a deterministic shape-correcting polishing process. Therefore, a new method for processing optical elements is needed, which can rapidly realize 1 μm PV level surface shape precision of workpieces and a high-efficiency processing method with roughness superior to Ra 10-20 nm.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: aiming at the technical problems in the prior art, the invention provides a time-controlled grinding method, a time-controlled grinding system and a time-controlled grinding medium for an optical element, so that the optical element with high efficiency, high surface shape precision and low surface roughness is machined.
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a time-controlled grinding method for optical elements comprises the following steps:
1) measuring to obtain initial surface shape error data of the workpiece;
2) configuring a time-controlled grinding machining head in the time-controlled grinding machining device according to an error amplitude-frequency analysis result of the initial surface shape error data;
3) selecting proper time-controlled grinding parameters according to the precision requirement of the workpiece;
4) processing on a sample by using the time-controlled grinding processing parameters, orthogonally contacting the time-controlled grinding processing head on the surface of the sample, and keeping constant-speed updating of a coating abrasive belt of the time-controlled grinding processing device to obtain a time-controlled grinding removal function;
5) extracting time-controlled grinding removal function data to perform simulation machining, returning to the step 3) if the simulation machining cannot meet the precision requirement, and entering the step 6) if the simulation machining precision meets the requirement;
6) and controlling the time-controlled grinding device to carry out deterministic shape-correcting polishing on the workpiece by using the time-controlled grinding parameter and the numerical control code generated by the simulation processing software.
Further, the step 1) specifically comprises the following steps:
1.1) if a contact type measuring method is used, directly entering the step 2) after surface shape data obtained by measurement is used as initial surface shape error data; if an interference measurement method is used, if the surface roughness of the workpiece meets the interference measurement requirement, the surface shape data obtained by measurement is directly entered into the step 2) as initial surface shape error data; if the roughness of the surface of the workpiece does not meet the requirement of interferometry, entering step 1.2);
1.2) quickly polishing the surface of the workpiece to ensure that the roughness of the surface of the workpiece meets the requirement of interferometry, and using the measured surface shape data as initial surface shape error data.
Further, the step 2) specifically comprises the following steps:
2.1) carrying out Fourier transform on the initial surface shape error data to obtain a normalized amplitude spectrum between the frequency and the amplitude of the surface shape error;
and 2.2) if the amplitude of the low-frequency error on the normalized amplitude spectrum is the largest, mounting a large-size contact wheel on the time-control grinding head of the time-control grinding device, and if the large-amplitude error component on the normalized amplitude spectrum is mainly concentrated on a medium-high frequency section, mounting a small-size contact wheel on the time-control grinding head of the time-control grinding device.
Further, the step 3) specifically comprises the following steps:
according to the processing requirements, the abrasive granularity and the contact pressure in the time-controlled grinding processing parameters are determined, and the vibration frequency and the updating speed of the coated abrasive belt in the time-controlled grinding processing parameters are adaptively adjusted on the basis of the two parameters.
Further, the step 4) specifically comprises the following steps:
the control-time grinding device is fixed relative to a sample holding position, the control-time grinding machining head orthogonally contacts a designated surface position of the sample, the contact pressure control-time grinding machining head presses the surface of the sample at constant pressure, the vibration frequency control-time grinding machining head vibrates, the coating abrasive belt updating speed is controlled to update the constant speed of the coating abrasive belt, the control-time grinding machining head leaves the current position after the preset retention time is reached, the material removal spots on the sample are detected, and the removal function distribution matrix is obtained.
The invention also provides a time-controlled grinding processing system of the optical element, which comprises a time-controlled grinding processing device arranged on a numerical control machine tool, wherein the time-controlled grinding processing device comprises a winding belt module, a speed measuring module, a time-controlled grinding processing head, a belt releasing module and a coated abrasive belt, which are arranged in a sliding box body, one end of the coated abrasive belt is wound on the winding belt module, and the other end of the coated abrasive belt relative to the winding belt module sequentially passes through the speed measuring module and the time-controlled grinding processing head and is connected with the belt releasing module, so that after the speed measuring module feeds back the updating speed of the coated abrasive belt, the winding belt module and the belt releasing module are respectively controlled to change the winding belt speed and the belt releasing speed.
Furthermore, the time-controlled grinding device further comprises a fixed base and an air cylinder, the fixed base is fixedly arranged on the numerical control machine tool, and the sliding box body is connected with the numerical control machine tool through the air cylinder.
Further, the grinding processing head is arranged in the sliding box body in a sliding mode in a time-controlled mode, a detachable contact wheel is arranged at the end of the time-controlled grinding processing head, and the contact wheel is in contact with an external sample piece or a workpiece through a coating abrasive belt.
Further, the numerical control machine tool comprises three linear motion units respectively corresponding to X, Y, Z shafts and three rotary motion units respectively corresponding to A, B, C directions, a workpiece or a sample to be machined is mounted on the rotary motion unit corresponding to the direction C, the rotary motion unit corresponding to the direction C is mounted on the linear motion unit corresponding to the axis X, the time-controlled grinding device is mounted on the rotary motion unit corresponding to the direction B, and the rotary motion unit corresponding to the direction B is mounted on the rotary motion unit corresponding to the direction A; the rotary motion units corresponding to the direction A are arranged on the corresponding linear motion units; the linear motion unit corresponding to the Z axis is arranged on the linear motion unit corresponding to the Y axis; the linear motion unit corresponding to the Y axis is arranged on the numerical control machine tool in a sliding manner. The invention also proposes a computer-readable storage medium having stored thereon a computer program programmed or configured to execute the above-mentioned time-controlled grinding method of an optical element.
Compared with the prior art, the invention has the advantages that:
the grinding precision of a traditional grinding machine depends on the motion precision of parts of the machine tool, the forming precision of a final workpiece is ensured by the motion track of a grinding wheel relative to the workpiece and is influenced by the motion precision of each part, such as the straightness of a guide rail, the verticality between the guide rails, the rotation precision of a grinding wheel shaft and the like, and the motion precision is more difficult to ensure along with the increase of the machining size of the machine tool, so that the surface shape precision is kept at the level of 5 mu m PV. The existing deterministic shape-correcting polishing process is generally low in efficiency, and the poor surface shape precision of the previous procedure can cause the shape-correcting polishing process to consume a large amount of manpower, time and material cost, so that the process is not beneficial to high-precision and high-efficiency processing of large-diameter optical elements.
The time-controlled grinding method and the time-controlled grinding equipment are based on a computer-controlled optical surface forming technology (CCOS), the time-controlled grinding processing head is always in orthogonal contact with the surface of a sample piece through a self-grinding time-controlled grinding processing device in the processing process, the constant-speed updating of a coating abrasive belt of the time-controlled grinding processing device is kept, the time linearity and the long-term stability of the material removal rate are realized, and the stable control of the size of a removal function is realized, so that the specific and accurate grinding removal amount of each position on the workpiece can be controlled by accurately controlling the stay of the specific time at different positions of the surface of the workpiece through a computer, the error low-point stay time is short, and the grinding removal amount is small; the high-point error has long retention time and large grinding removal amount, thereby achieving the surface shape precision superior to 1 mu m PV. Compared with the traditional grinding machine, the grinding machine does not highly depend on the motion precision of the machine tool, removes materials with different volumes by controlling the grinding time of each position on the surface of the workpiece, and achieves the machining precision superior to that of the traditional precision grinding machine. Compared with the existing deterministic shaping polishing process, the time-controlled grinding material removal efficiency is high and can exceed 10 times of magnetorheological deterministic polishing, and the processing efficiency is controllable. In addition, the coated abrasive polishing belt is wide in series, easy to obtain, suitable for various materials and working conditions, high in efficiency, precision and adaptability, high in material removal rate, good in surface quality of a processed workpiece and the like, can be matched with a time-controlled grinding method, can greatly shorten the manufacturing period of a high-precision optical element, and particularly has obvious advantages in the processing efficiency of a large-caliber optical element.
Drawings
Fig. 1 is a schematic basic flow chart according to a first embodiment of the present invention.
FIG. 2 is a three-dimensional and two-dimensional topography of one of the removal functions according to a first embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a time-controlled grinding system according to a second embodiment of the present invention.
Fig. 4 is a schematic diagram of a feeding path of a grinding system in different linkage modes of a motion axis in the middle control process according to the second embodiment of the present invention.
Fig. 5 is a schematic diagram illustrating adjustment of a contact posture between the grinding apparatus and the workpiece in the second control process according to the embodiment of the present invention.
Fig. 6 is a schematic structural diagram of a time-controlled grinding device according to a second embodiment of the present invention.
Fig. 7 is a schematic diagram of an actual movement track of the grinding processing head in the middle control process according to the second embodiment of the present invention.
Illustration of the drawings: 1-a numerical control machine tool, 2-a time-controlled grinding machining device, 3-a workpiece, 12-X-axis slide carriage, 13-Y-axis slide carriage, 14-Z-axis slide carriage, 15-A-axis rotary table, 16-B-axis rotary table, 17-C-axis rotary table, 21-fixed base, 22-sliding box body, 23, tape coiling module, 24-speed measuring module, 25-a time-controlled grinding machining head, 26-cylinder, 27-tape releasing module and 28-coated abrasive tape.
Detailed Description
The invention is further described below with reference to the drawings and specific preferred embodiments of the description, without thereby limiting the scope of protection of the invention.
Example one
As shown in fig. 1, the present embodiment provides a time-controlled grinding method for an optical element, including the following steps:
1) measuring initial surface error data of an optical element to be processed (hereinafter collectively referred to as a workpiece);
2) configuring a time-controlled grinding machining head in the time-controlled grinding machining device according to an error amplitude-frequency analysis result of the initial surface shape error data;
3) selecting proper time-controlled grinding parameters according to the precision requirement of the workpiece;
4) processing on a sample by using the time-controlled grinding processing parameters, orthogonally contacting the time-controlled grinding processing head on the surface of the sample, and keeping constant-speed updating of a coating abrasive belt of the time-controlled grinding processing device to obtain a time-controlled grinding removal function;
5) extracting time control grinding to obtain removal function data for simulation machining, returning to the step 3) if the simulation machining cannot meet the precision requirement, and entering the step 7) if the simulation machining precision meets the requirement;
6) and controlling the time-controlled grinding device to carry out deterministic shape-correcting polishing on the workpiece by using the time-controlled grinding parameter and the numerical control code generated by the simulation processing software.
The time-controlled grinding machining head is always in orthogonal contact with the surface of the sample piece in the machining process, and the constant-speed updating of a coating abrasive belt of the time-controlled grinding machining device is kept, so that the time linearity and the long-term stability of the material removal rate are realized, and the stable control of the size of a removal function is realized, so that the specific and accurate grinding removal amount of each position on the workpiece can be controlled by accurately controlling the specific time of staying at different positions on the surface of the workpiece through a computer, the low-point error staying time is short, and the grinding removal amount is small; the high-point error has long retention time and large grinding removal amount, thereby achieving the surface shape precision superior to 1 mu m PV.
In this embodiment, step 1) specifically includes the following steps:
1.1) if a contact type measuring method is used, if a three-coordinate instrument is used, taking the surface shape data obtained by measurement as initial surface shape error data and then directly entering the step 2); if an interference measurement method is used, if the surface roughness of the workpiece meets the interference measurement requirement, directly taking the measured surface shape data as initial surface shape error data and then directly entering the step 2); if the roughness of the surface of the workpiece does not meet the requirement of interferometry, entering step 1.2);
1.2) quickly polishing the surface of the workpiece to ensure that the roughness of the surface of the workpiece meets the requirement of interference measurement, and taking the measured surface shape data as initial surface shape error data.
In this embodiment, step 2) specifically includes the following steps:
2.1) carrying out Fourier transform on the initial surface shape error data to obtain a normalized amplitude spectrum between the frequency and the amplitude of the surface shape error;
2.2) according to the step 2.1), if the amplitude of the low-frequency error on the normalized amplitude spectrum is the largest, installing a large-size contact wheel on the time-control grinding device, and if the large-amplitude error component on the normalized amplitude spectrum is mainly concentrated on a middle-high frequency section, installing a contact wheel with a smaller size on the time-control grinding device.
In the embodiment, the time-controlled grinding method belongs to a CCOS deterministic processing method, has different error correction efficiencies and capacities for removal functions with different amplitude-frequency characteristics, and is suitable for workpieces with different surface shape error characteristics. The removal function generated by the large-size contact wheel is suitable for correcting low-frequency error components with longer spatial wavelength, and the corresponding removal function gradually has stronger high-frequency error correction capability along with the reduction of the size of the contact wheel, so that the removal function is suitable for correcting errors with smaller spatial wavelength.
In this embodiment, step 3) specifically includes the following steps:
the technological parameters in the time-controlled grinding processing method mainly comprise contact pressure, abrasive particle size, vibration frequency, updating speed of a coated abrasive belt and the like. After the contact wheel has been dimensioned in step 2.2), the abrasive grain size and the contact pressure are first determined according to the processing requirements, and the remaining processing parameters are adapted on the basis of these two parameters to meet the desired material removal. All process parameters need to be held constant during a single pass to ensure a stable removal function to ensure that it can be used for deterministic shape finishing polishing. The three-dimensional and two-dimensional topography of the removal function generated by one set of processing parameters is shown in fig. 2.
In this embodiment, the contact pressure may be adjusted within a certain range, which may affect the material removal efficiency and surface roughness, and the contact pressure must be kept constant in any single machining process; the granularity of the coated abrasive belt is a dominant factor of material removal efficiency, the removal efficiency of the coated abrasive belt with large granularity is higher, and the removal efficiency of the coated abrasive belt with small granularity is opposite; in the time-controlled grinding method, the reciprocating vibration is the main motion of grinding and removing the material, the vibration frequency mainly influences the material removing efficiency and the surface roughness, the higher the vibration frequency is, the higher the material removing efficiency is, and the lower the surface roughness is, and on the contrary, the lower the material removing efficiency is, and the better the surface roughness is. The renewal rate of the coated abrasive belt primarily affects the shape of the removal function and also affects the material removal efficiency. The processing technological parameters have mutual coupling effect in practice, different time-controlled grinding processing parameter combinations can generate different removal functions, and the method is suitable for different processing requirements.
Step 4) of this embodiment specifically includes the following steps: selecting a sample piece of which the material and the curvature radius are the same as those of an actual workpiece but the overall size is only one part of the actual workpiece, keeping the position of a grinding machining device relative to the sample piece immovable during control respectively, enabling a grinding machining head to be in orthogonal contact with a specified surface position of the sample piece during control, enabling the grinding machining head to be pressed on the surface of the sample piece at constant pressure during control according to the contact pressure, keeping vibration of the grinding machining head during control according to the vibration frequency, controlling constant-speed updating of a coating abrasive belt according to the updating speed of the coating abrasive belt, enabling the grinding machining head to leave the current position after preset retention time is reached, detecting material removal spots on the sample piece, and obtaining a removal function distribution matrix.
In this embodiment, the designated position on the surface of the sample may be one or a few positions (multiple positions and fixed points can reduce the occurrence of accidental situations, and ensure the accuracy of the removal function).
The step 5) of this embodiment of extracting the time-controlled grinding removal function data for simulation processing specifically includes:
inputting the two data into time-controlled grinding processing software according to the removal function obtained in the step 4) and the initial surface shape error data obtained in the step 1), wherein the processing software can calculate the residence time of the time-controlled grinding processing head at each position of the surface of the workpiece, and calculate the residual surface shape error data of the surface of the workpiece after simulation processing. According to the initial surface shape error data, the surface shape condition of each position of the workpiece can be obtained, the removal amount in the preset time can be obtained through the removal function of sample processing, and the staying time at each position of the workpiece can be calculated through the removal amount according to the linear relation between the removal amount and the time.
Step 6) of this embodiment is performed based on the CCOS principle, and includes the specific steps of: the method comprises the steps of controlling a time-controlled grinding machining head to be in orthogonal contact with a position to be machined on the surface of a workpiece, controlling the time-controlled grinding machining head to be pressed on the surface of the workpiece at a constant pressure according to contact pressure, keeping the time-controlled grinding machining head to vibrate according to vibration frequency, controlling a coated abrasive belt to be updated at a constant speed according to the updating speed of the coated abrasive belt, controlling the time-controlled grinding machining head to leave the current position and move to the next position after reaching preset retention time until all the positions to be machined are machined, controlling the time-controlled grinding machining device to stay at the position for a longer time when a machining track approaches a high point of the surface error of the workpiece, and removing more materials at the position, otherwise, controlling the time-controlled grinding machining device to stay at the position for a shorter time when the machining track approaches the low point of the surface error of the workpiece, so as to remove a smaller amount of materials.
Example two
The present embodiment provides a time-controlled grinding system for optical elements according to the method in the first embodiment, as shown in fig. 3, which is composed of a numerical control machine 1, a time-controlled grinding device 2, and a control module, where the control module may be a computer or a programmable chip with a program written thereon, the control ends of the numerical control machine 1 and the time-controlled grinding device 2 are respectively connected to the control module, the numerical control machine 1 includes three linear motion axes corresponding to X, Y, Z axes respectively and three rotation axes corresponding to A, B, C directions respectively, the linear motion axes include an X-axis carriage 12, a Y-axis carriage 13, and a Z-axis carriage 14, and the rotation axes include an a-axis turntable 15, a B-axis turntable 16, and a C-axis turntable 17. The workpiece 3 is arranged on the C-axis rotary table 17, the C-axis rotary table 17 is arranged on the X-axis slide carriage 12, and the feeding in the X-axis direction and the servo rotation in the C direction can be realized. The time-controlled grinding device 2 is arranged on a B-axis turntable 16 and can rotate along a B axis in a servo mode; the B-axis turntable 16 is arranged on the A-axis turntable 15 and can rotate along the A-axis in a servo mode; the A-axis turntable 15 is arranged on the Z-axis slide carriage 14 and can perform servo feeding along the Z-axis direction; the Z-axis slide carriage 14 is arranged on the Y-axis slide carriage 13 and can perform servo feeding along the Y-axis direction; the Y-axis slide carriage 13 is slidably arranged on the bed of the numerical control machine tool 1 and performs servo feeding within the stroke range of the bed of the numerical control machine tool 1.
In this embodiment, the time-controlled grinding system can remove the material at each position on the surface of the workpiece 3 by the time-controlled grinding device 2 under the coordinated control of the X-axis carriage 12, the Y-axis carriage 13, and the C-axis turntable 17. When the X-axis slide carriage 12 and the Y-axis slide carriage 13 are fed in a linkage manner, a grating feeding track as shown in figure 4 can be realized; when the X-axis carriage 12 or the Y-axis carriage 13 is controlled in linkage with the C-axis turntable 17, the spiral feeding track shown in FIG. 5 can be realized.
In this embodiment, the Z-axis carriage 14, the a-axis turntable 15, and the B-axis turntable 16 jointly drive the time-controlled grinding apparatus 2 to perform the attitude adjustment as shown in fig. 6, so as to ensure that the time-controlled grinding apparatus 2 always contacts the surface of the workpiece 3 in an orthogonal manner, and ensure the stability of the time-controlled grinding removal function.
In the present embodiment, as shown in fig. 5, the time-controlled grinding device 2 is mainly composed of a fixed base 21, a slide case 22, a tape winding module 23, a speed measuring module 24, a time-controlled grinding head 25, an air cylinder 26, a tape releasing module 27, and a coated abrasive tape 28. Wherein, the fixed base 21 is fixedly connected to the B-axis turntable 16, the sliding box 22 is slidably disposed on the fixed base 21, and two ends of the cylinder 26 are respectively connected to the fixed base 21 and the sliding box 22. Under the action of the air cylinder 26, the sliding box 22 can be ejected and retracted on the fixed base 21 along the telescopic direction of the air cylinder 26. The tape winding module 23, the speed measuring module 24 and the tape releasing module 27 are all installed in the sliding box 22 and used for driving the coating abrasive tape 28 to be continuously updated. The belt pay-off module 27 is driven by a constant torque device to ensure constant tension of the coated abrasive belt during processing. The coating abrasive belt 28 is open, one end of the coating abrasive belt is installed on the reel of the belt releasing module 27, the grinding machining head 25 and the speed measuring module 24 are controlled, and the other end of the coating abrasive belt is wound on the reel of the belt winding module 23. The machining head 25 is slidably disposed on the sliding box 22 and can perform a vibration motion in a one-dimensional direction, and both the vibration frequency and the vibration amplitude are adjustable. The controlled grinding machining head 25 is provided with a replaceable flexible contact wheel, the surface of which is covered with a coated abrasive belt 28, and the contact wheel is contacted with an external workpiece 3 or sample piece through the coated abrasive belt 28.
In this embodiment, the speed measuring module 24 may be a speed sensor or a displacement sensor, the collecting end of the speed measuring module 24 contacts with the inner side of the coating abrasive belt 28, so as to collect the update speed of the coating abrasive belt 28 in real time, and feed back the update speed to the control module, the control module controls the winding module 23 and the unwinding module 27 to change the angular speed of the corresponding reel, so as to keep the update speed of the coating abrasive belt 28 unchanged, in practical use, as the usage time changes, the reel of the winding module 23 becomes larger and larger along with the collected coating abrasive belt 28, and the reel of the unwinding module 27 becomes smaller and smaller along with the unwound coating abrasive belt 28, so the reel angular speed of the winding module 23 gradually decreases, and the reel angular speed of the unwinding module 27 gradually increases.
In this embodiment, the time-controlled grinding system for optical elements implements the specific process of step 4) of the first embodiment as follows:
when a removal function is obtained, a sample piece with the same material and curvature radius as the workpiece 3 is clamped on the C-axis turntable 17, the control module controls the time-controlled grinding device 2 to be fixed relative to the sample piece holding position, the time-controlled grinding machining head 25 is in orthogonal contact with the designated position of the surface of the sample piece, the control cylinder 26 is controlled to introduce compressed air with constant pressure according to the contact pressure in the time-controlled grinding machining parameters to push the sliding box 22 to pop out, the time-controlled grinding machining head 25 at the tail end of the sliding box 22 is pressed on the surface of the sample piece with constant pressure, the time-controlled grinding machining head 25 is kept vibrating according to the vibration frequency in the time-controlled grinding machining parameters, the reel angular speeds of the abrasive tape coiling module 23 and the tape unreeling module 27 are controlled according to the coating tape updating speed in the time-controlled grinding machining parameters, and the reel angular speeds of the abrasive tape coiling module 23 and unreeling module 27 are adjusted according to the speed information fed back by the speed measuring module 24 in real time, to ensure constant renewal of the coated abrasive belt 28. After the specific time, the grinding machining head 25 is controlled to leave the sample piece, the material on the sample piece is detected through the detection equipment to remove spots, and a removal function distribution matrix is obtained. The time-controlled grinding parameters in step 3.1) all influence the distribution characteristics of the final removal function matrix.
In this embodiment, the step 5) of implementing the first embodiment by the time-controlled grinding system for optical elements specifically includes the following steps:
inputting the two data into time-controlled grinding processing software according to the removal function obtained in the step 4) and the initial surface shape error data obtained in the step 1), wherein the processing software can calculate the residence time of the time-controlled grinding processing head 25 at each position of the surface of the workpiece, and calculate the residual surface shape error of the surface of the workpiece after simulation processing. If the amplitude of the residual surface shape error is within the expected requirement, the calculated residence time can be converted into a numerical control code of the machine tool in the process software, and the numerical control code is imported into the machine tool for actual machining. And if the machining requirements are not met, returning to the step 3) to start to adjust the machining parameters.
In this embodiment, the step 6) of implementing the first embodiment by the time-controlled grinding system for an optical element specifically includes the following steps:
the time-controlled grinding machining is carried out based on the CCOS principle, when machining is started, the air cylinder 26 is controlled to be filled with compressed air with constant pressure according to contact pressure in time-controlled grinding machining parameters to push the sliding box body 22 to pop up, the time-controlled grinding machining head 25 at the tail end of the sliding box body 22 presses the surface of the workpiece 3 with constant pressure, and the action line of the air cylinder 26 is enabled to be coincident with the normal line of the tangent position of the workpiece 3 and the contact wheel through linkage of the A-axis turntable 15 and the B-axis turntable 16. The unwind module 27 is provided with a constant tightening torque and the reel of the wind-up module 23 is servo-rotated by a motor to bring the coated abrasive tape 28 continuously fresh. The speed measuring module 24 is in contact with the coating abrasive belt 28, the control module performs feedback adjustment on the motor of the winding module 23 through the actual linear speed of the coating abrasive belt 28 detected by the speed measuring module 24, so that the linear speed of the coating abrasive belt 28 is kept constant, and the shape stability of a removal function in a grinding area where the grinding processing head 25 is in contact with the workpiece 3 during control is ensured. Simultaneously, the grinding machining head 25 is set in a vibrating motion with a frequency and amplitude which produces the desired material removal by relative grinding between the abrasive particles on the coated abrasive belt 28 and the workpiece 3. In the machining process, when the machining track approaches the surface error high point of the workpiece 3, the time-controlled grinding machining device 2 stays at the position for a long time, and the time-controlled grinding machining head 25 removes more materials at the position, on the contrary, when the machining track approaches the surface error low point of the workpiece 3, the control module controls the corresponding movement axis on the numerical control machine 1 to improve the movement speed, and drives the time-controlled grinding machining device 2 to quickly pass through the error low point position on the workpiece 3 so as to remove a small amount of materials. In the machining process, the machine tool is responsible for carrying out variable speed motion according to the corresponding motion shaft of the motion of the machining track and keeping an accurate linkage state under the control of a numerical control system of the machine tool. When the controlled-time grinding device 2 performs the feeding motion and the oscillating motion relative to the workpiece 3, the actual combined track of the workpiece is as shown in fig. 7, and the combination of the two motions makes the actual machining track become cross-disordered, which is beneficial to generating good surface roughness.
EXAMPLE III
The present embodiment proposes a computer-readable storage medium having stored thereon a computer program programmed or configured to perform the time-controlled grinding method of the optical element of the first embodiment.
The foregoing is considered as illustrative of the preferred embodiments of the invention and is not to be construed as limiting the invention in any way. In the present embodiment, the time-controlled grinding device 2 is mounted on the body of the numerically controlled machine tool 1 as shown in fig. 3, and this machine tool is used only for illustrating the present embodiment, and the present invention does not limit the time-controlled grinding device 2 to be mounted only on such a body of the numerically controlled machine tool 1. Any numerically controlled machine tool body with a corresponding servo linear motion axis and a servo rotary motion axis can be provided with the time-controlled grinding device 2, so that time-controlled grinding machining of optical elements with different calibers can be carried out, and the movement stroke of the numerically controlled machine tool body determines the maximum size of a machined workpiece. Those skilled in the art can make numerous possible variations and modifications to the present invention, or modify equivalent embodiments to equivalent variations, without departing from the scope of the invention, using the teachings disclosed above. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention should fall within the protection scope of the technical scheme of the present invention, unless the technical spirit of the present invention departs from the content of the technical scheme of the present invention.
Claims (10)
1. A time-controlled grinding method for an optical element is characterized by comprising the following steps:
1) measuring to obtain initial surface shape error data of the workpiece;
2) configuring a time-controlled grinding machining head in the time-controlled grinding machining device according to the amplitude-frequency analysis result of the initial surface shape error data;
3) selecting time-controlled grinding parameters according to the precision requirement of the workpiece;
4) processing on a sample by using the time-controlled grinding processing parameters, orthogonally contacting the time-controlled grinding processing head on the surface of the sample, and keeping constant-speed updating of a coating abrasive belt of the time-controlled grinding processing device to obtain a time-controlled grinding removal function;
5) extracting time-controlled grinding removal function data to perform simulation machining, returning to the step 3) if the simulation machining cannot meet the precision requirement, and entering the step 6) if the simulation machining precision meets the requirement;
6) and controlling the time-controlled grinding device to carry out deterministic shape-correcting polishing on the workpiece by using the time-controlled grinding parameter and the numerical control code generated by the simulation processing software.
2. The time-controlled grinding method for optical elements according to claim 1, wherein step 1) comprises the following steps:
1.1) if a contact type measuring method is used, directly entering the step 2) after surface shape data obtained by measurement is used as initial surface shape error data; if an interference measurement method is used, if the surface roughness of the workpiece meets the interference measurement requirement, the surface shape data obtained by measurement is directly entered into the step 2) as initial surface shape error data; if the roughness of the surface of the workpiece does not meet the requirement of interferometry, entering step 1.2);
1.2) quickly polishing the surface of the workpiece to ensure that the roughness of the surface of the workpiece meets the requirement of interferometry, and using the measured surface shape data as initial surface shape error data.
3. A method for time-controlled grinding of an optical element according to claim 1, wherein step 2) comprises in particular the steps of:
2.1) carrying out Fourier transform on the initial surface shape error data to obtain a normalized amplitude spectrum between the frequency and the amplitude of the surface shape error;
and 2.2) if the amplitude of the low-frequency error on the normalized amplitude spectrum is the largest, mounting a large-size contact wheel on the time-control grinding head of the time-control grinding device, and if the large-amplitude error component on the normalized amplitude spectrum is mainly concentrated on a medium-high frequency section, mounting a small-size contact wheel on the time-control grinding head of the time-control grinding device.
4. A method for time-controlled grinding of an optical element according to claim 1, wherein step 3) comprises in particular the steps of: according to the processing requirements, the abrasive granularity and the contact pressure in the time-controlled grinding processing parameters are determined, and the vibration frequency and the updating speed of the coated abrasive belt in the time-controlled grinding processing parameters are adaptively adjusted on the basis of the two parameters.
5. The time-controlled grinding method for optical elements according to claim 4, wherein step 4) comprises the following steps:
the control-time grinding device is fixed relative to a sample holding position, the control-time grinding machining head orthogonally contacts a designated surface position of the sample, the contact pressure control-time grinding machining head presses the surface of the sample at constant pressure, the vibration frequency control-time grinding machining head vibrates, the coating abrasive belt updating speed is controlled to update the constant speed of the coating abrasive belt, the control-time grinding machining head leaves the current position after the preset retention time is reached, the material removal spots on the sample are detected, and the removal function distribution matrix is obtained.
6. A time-controlled grinding system for optical elements is characterized by comprising a time-controlled grinding device (2) arranged on a numerical control machine (1), the time-controlled grinding device (2) comprises a winding module (23), a speed measuring module (24), a time-controlled grinding head (25), a belt releasing module (27) and a coated abrasive belt (28) which are arranged in a sliding box body (22), one end of the coated abrasive belt (28) is wound on the tape and reel module (23), and the other end of the coating abrasive belt (28) relative to the belt winding module (23) passes through the speed measuring module (24) and the time-controlled grinding processing head (25) in sequence, and a belt releasing module (27) are connected, so that after the speed measuring module (24) feeds back the updated speed of the coated abrasive belt (28), the tape coiling module (23) and the tape releasing module (27) are respectively controlled to change the tape coiling speed and the tape releasing speed.
7. The time-controlled grinding system of the optical element according to claim 5, wherein the time-controlled grinding device (2) further comprises a fixed base (21) and a cylinder (26), the fixed base (21) is fixedly arranged on the numerical control machine (1), and the sliding box (22) is connected with the numerical control machine (1) through the cylinder (26).
8. The time-controlled grinding system for optical elements according to claim 5, characterized in that the time-controlled grinding head (25) is arranged slidably in a sliding housing (22), the end of the time-controlled grinding head (25) being provided with a detachable contact wheel which is brought into contact with an external sample or workpiece by means of a coated abrasive tape (28).
9. The time-controlled grinding system for optical elements according to claim 5, wherein the numerically controlled machine tool (1) comprises three linear motion units corresponding to X, Y, Z axes respectively and three rotary motion units corresponding to A, B, C directions respectively, a workpiece or sample to be machined is mounted on the rotary motion unit corresponding to the C direction, the rotary motion unit corresponding to the C direction is mounted on the linear motion unit corresponding to the X axis, the time-controlled grinding device (2) is mounted on the rotary motion unit corresponding to the B direction, and the rotary motion unit corresponding to the B direction is mounted on the rotary motion unit corresponding to the A direction; the rotary motion unit corresponding to the direction A is arranged on the linear motion unit corresponding to the Z axis; the linear motion unit corresponding to the Z axis is arranged on the linear motion unit corresponding to the Y axis; the linear motion unit corresponding to the Y axis is arranged on the numerical control machine tool (1) in a sliding mode.
10. A computer-readable storage medium, characterized in that the computer-readable storage medium has stored thereon a computer program programmed or configured with a time-controlled grinding method of an optical element according to any one of claims 1 to 5.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111227785.2A CN113829135B (en) | 2021-10-21 | 2021-10-21 | Time-controlled grinding method, system and medium for optical element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111227785.2A CN113829135B (en) | 2021-10-21 | 2021-10-21 | Time-controlled grinding method, system and medium for optical element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113829135A true CN113829135A (en) | 2021-12-24 |
| CN113829135B CN113829135B (en) | 2022-12-27 |
Family
ID=78965703
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111227785.2A Active CN113829135B (en) | 2021-10-21 | 2021-10-21 | Time-controlled grinding method, system and medium for optical element |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113829135B (en) |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070259608A1 (en) * | 2006-05-03 | 2007-11-08 | Bechtold Michael J | Method and apparatus for precision polishing of optical components |
| JP2007326212A (en) * | 2006-06-09 | 2007-12-20 | Snu Precision Co Ltd | Device and method for repairing substrate |
| CN102560936A (en) * | 2011-12-13 | 2012-07-11 | 天邦膜技术国家工程研究中心有限责任公司 | Automatic constant-linear-speed control system of film applicator |
| CN105014503A (en) * | 2015-05-19 | 2015-11-04 | 上海交通大学 | Precise grinding method for large-caliber axisymmetric aspheric surfaces |
| CN107283260A (en) * | 2017-07-07 | 2017-10-24 | 常州爱思飞光学仪器有限公司 | A kind of wheeled burnishing device |
| CN110202418A (en) * | 2019-05-30 | 2019-09-06 | 中国人民解放军国防科技大学 | Method for determining abrasive belt shape modification of outer circle surface of shaft part |
| CN111843754A (en) * | 2020-07-31 | 2020-10-30 | 中国人民解放军国防科技大学 | Method for determinacy shaping excircle roundness of shaft part |
| CN112428026A (en) * | 2020-11-13 | 2021-03-02 | 中国人民解放军国防科技大学 | Pulse control beam diameter adjustable ion beam processing method based on surface shape error frequency band |
| CN112847017A (en) * | 2021-03-10 | 2021-05-28 | 湖南大敏尚东精密机械有限公司 | Polishing equipment for multi-axis free-form surface optical element and working method |
| CN113059487A (en) * | 2021-04-26 | 2021-07-02 | 湖南大敏尚东精密机械有限公司 | Multifunctional magnetorheological polishing wheel quick switching device and working method |
-
2021
- 2021-10-21 CN CN202111227785.2A patent/CN113829135B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070259608A1 (en) * | 2006-05-03 | 2007-11-08 | Bechtold Michael J | Method and apparatus for precision polishing of optical components |
| JP2007326212A (en) * | 2006-06-09 | 2007-12-20 | Snu Precision Co Ltd | Device and method for repairing substrate |
| CN102560936A (en) * | 2011-12-13 | 2012-07-11 | 天邦膜技术国家工程研究中心有限责任公司 | Automatic constant-linear-speed control system of film applicator |
| CN105014503A (en) * | 2015-05-19 | 2015-11-04 | 上海交通大学 | Precise grinding method for large-caliber axisymmetric aspheric surfaces |
| CN107283260A (en) * | 2017-07-07 | 2017-10-24 | 常州爱思飞光学仪器有限公司 | A kind of wheeled burnishing device |
| CN110202418A (en) * | 2019-05-30 | 2019-09-06 | 中国人民解放军国防科技大学 | Method for determining abrasive belt shape modification of outer circle surface of shaft part |
| CN111843754A (en) * | 2020-07-31 | 2020-10-30 | 中国人民解放军国防科技大学 | Method for determinacy shaping excircle roundness of shaft part |
| CN112428026A (en) * | 2020-11-13 | 2021-03-02 | 中国人民解放军国防科技大学 | Pulse control beam diameter adjustable ion beam processing method based on surface shape error frequency band |
| CN112847017A (en) * | 2021-03-10 | 2021-05-28 | 湖南大敏尚东精密机械有限公司 | Polishing equipment for multi-axis free-form surface optical element and working method |
| CN113059487A (en) * | 2021-04-26 | 2021-07-02 | 湖南大敏尚东精密机械有限公司 | Multifunctional magnetorheological polishing wheel quick switching device and working method |
Non-Patent Citations (2)
| Title |
|---|
| 李宁等: "光学面形的轮带光学抛光方法研究", 《应用光学》 * |
| 闫惠刚等: "轮带光学抛光技术与实验研究", 《航空精密制造技术》 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113829135B (en) | 2022-12-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4850152A (en) | Apparatus for lapping and polishing optical surfaces | |
| TWI533966B (en) | Systems and methods for machining materials | |
| CN101983838B (en) | Milling, grinding and polishing device based on intelligent numerically-controlled platform | |
| US20010024934A1 (en) | Method of grinding an axially asymmetric aspherical mirror | |
| CN102922388A (en) | Precise polishing robot system for large-caliber complex optical lenses | |
| CN105729305A (en) | Force position coupling micro-motion precise polishing device and online force detection and control method | |
| CN105598808A (en) | Automatic polishing system and method | |
| CN109968204A (en) | A kind of numerical control grinding form error self-adapting compensation method that grinding wheel workpiece is mutually worn | |
| CN111347294B (en) | High-gradient optical mirror surface error polishing correction processing method | |
| US6592430B1 (en) | High-precision machining system | |
| CN110450014A (en) | A kind of high frequency micro amplitude vibration device applied to the complex-curved ultrafast polishing of heavy caliber | |
| Wu et al. | A novel force-controlled spherical polishing tool combined with self-rotation and co-rotation motion | |
| CN113829135B (en) | Time-controlled grinding method, system and medium for optical element | |
| US5107628A (en) | Method of fabricating article having aspheric figure and tool for use in carrying out the method | |
| Tian et al. | Fast tool servo diamond turning of optical freeform surfaces for rear-view mirrors | |
| Jones | Grinding and polishing with small tools under computer control | |
| Shimeng et al. | Profile error compensation in precision grinding of ellipsoid optical surface | |
| US4905417A (en) | Numerical control grinding machine | |
| JP3890186B2 (en) | Polishing method, optical element and mold for molding optical element | |
| WO1995009714A1 (en) | Robotic polishing of planar and non-planar surfaces | |
| CN112847015B (en) | Device and method for processing optical element by cooperation of multiple robots | |
| US4628643A (en) | Grinding wheel infeed control method | |
| CN110227994B (en) | High-order contact enveloping type grinding and polishing processing method and application thereof | |
| CN110202418B (en) | Method for determining abrasive belt shape modification of outer circle surface of shaft part | |
| Li et al. | On-machine self-calibration method for compensation during precision fabrication of 900-mm-diameter zerodur aspheric mirror |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |