Microlens array forming method and device based on synchronous rotation of main shafts

Abstract

The application discloses a kind of micro-lens array shaping method and device based on main shaft synchronous rotation, it is related to ultra-precision machining technical field.The method utilizes the milling cutter with single cutting edge and the rotation envelope surface is spherical, establishes the constant rotational speed ratio synchronous coupling relationship of milling spindle and workpiece spindle;By driving two main shafts to rotate and control rotation direction, utilize the high-speed rotating motion of workpiece to compensate the speed loss of milling cutter rotation center, construct the non-zero relative cutting line speed vector at cutting contact point by vector synthesis, to eliminate cutting dead zone from physical principle;Using fixed shaft envelope forming process, control tool to cut into predetermined depth and keep position unchanged, maintain synchronous rotation continues integer multiple period time to directly generate micro-lens topography.The present application effectively eliminates the zero speed ploughing phenomenon of traditional micro-milling, realizes optical grade processing quality, and does not need to generate point cloud tool path, processing efficiency is compared with traditional process several orders of magnitude.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ultra-precision machining, and particularly relates to a microlens array forming method and device based on synchronous rotation of a main shaft for realizing high-efficiency cutting by synchronous rotation of double main shafts. BACKGROUND

[0002] Microlens arrays are widely used in optical systems such as optical communication, imaging and display, and the surface roughness thereof is usually required to reach the nanometer level. At present, the mainstream technologies for manufacturing such microstructures mainly include single-point diamond turning combined with slow tool servo technology and ultra-precision micro-milling technology. However, the slow tool servo technology is limited by the dynamic response frequency of the linear feed shaft, and the machining efficiency is extremely low, which is difficult to meet the large-scale production demand; and the traditional micro-milling technology is subject to the geometric characteristics of the ball-end milling cutter, and the linear speed at the rotation center (vertex) thereof tends to be zero, which leads to the degeneration of the cutting process in the center region of the lens into material extrusion or plowing, and it is difficult to obtain uniform and consistent optical surface quality. In addition, the existing machining methods usually rely on complex point cloud tool path programming, and the data processing amount is large and the process preparation is complicated. SUMMARY

[0003] The present application aims to solve the technical problems that the existing traditional micro-milling technology has a poor microlens surface quality due to the cutting dead zone of the milling cutter at the intersection of the spherical rotary envelope surface and the rotation axis, the traditional slow tool servo technology has a low machining efficiency due to the limitation of the dynamic response performance of the linear feed shaft, and the existing microstructure array machining excessively relies on complex point cloud tool path programming.

[0004] The microlens array forming method based on synchronous rotation of a main shaft provided by the present application comprises the following steps:

[0005] S1, mounting a workpiece to be machined on a workpiece main shaft, mounting a milling cutter with a single cutting edge and a spherical rotary envelope surface on a milling main shaft, and configuring the workpiece main shaft and the milling main shaft to have a preset angle distribution, and then controlling the milling cutter to move to an initial cutting position of the workpiece;

[0006] S2, determining the number N of microlens units to be generated on the current cutting track in one rotation of the workpiece according to the current cutting position of the workpiece, and locking the rotation speed of the milling main shaft and the rotation speed of the workpiece main shaft as a constant speed ratio, that is,

[0007] ​​​S3, driving the workpiece spindle and the milling spindle to rotate and controlling the rotation directions of both, so that at the current cutting position of the milling cutter and the workpiece, the tangential linear velocity vector generated by the rotation of the milling cutter and the tangential linear velocity vector generated by the rotation of the workpiece are vector-superimposed to form a non-zero relative cutting linear velocity vector between the milling cutter and the workpiece at the current cutting position;

[0008] S4, controlling the milling spindle and the workpiece spindle to generate relative cutting feed until the milling cutter cuts into the workpiece to a predetermined cutting depth, and then keeping the cutting depth of the milling cutter unchanged, using the relative motion envelope of the spherical revolution envelope formed by the rotation of the milling cutter and the rotation surface of the workpiece to generate the geometric morphology of the microlens unit directly on the workpiece; during this process, the milling spindle and the workpiece spindle are maintained to rotate according to the speed ratio in step S2 and the rotation direction in step S3 and for a time T, the time T being an integer multiple of the rotation period of the workpiece spindle;

[0009] S5, after the workpiece spindle completes at least one rotation, controlling the milling spindle and the workpiece spindle to generate relative motion so that the milling cutter moves a step distance relative to the workpiece along the preset microlens array arrangement direction;

[0010] S6, repeating steps S2 to S5 until a complete microlens array is generated on the workpiece.

[0011] As a preference, the preset angle distribution in step S1 and the vector superposition in step S3 are configured according to the type of the workpiece as one of the following two modes:

[0012] When the workpiece is a rotation body roller, the rotation axis of the workpiece spindle and the rotation axis of the milling spindle are configured to be non-planar and perpendicular in space, the linear velocity vectors of the milling cutter and the workpiece are in an orthogonal state at the cutting contact position, and the non-zero relative cutting linear velocity vector is formed by vector superposition;

[0013] When the workpiece is a planar substrate, the rotation axis of the workpiece spindle and the rotation axis of the milling spindle are configured to be non-parallel and inclined, so that the projections of the linear velocity vectors of the milling cutter and the workpiece on the cutting contact plane are in the same direction, and the linear velocity vector of the milling cutter is greater than the linear velocity vector of the workpiece, and the non-zero relative cutting linear velocity vector is formed by subtracting the linear velocity vector of the workpiece from the linear velocity vector of the milling cutter.

[0014] As a preference, the number N of the microlens units in step S2, the rotational speed of the milling spindle and the rotational speed of the workpiece spindle The determination comprises the following steps:

[0015] Step one, obtaining the maximum surface width LW of a single microlens unit along the workpiece axial direction; and according to the radius r of the spherical envelope surface of the milling cutter, the cutting depth d required for the milling cutter to process the microlens unit is reversely calculated by using the following geometric relationship: ;

[0016] Step two, obtaining the maximum surface arc length LL of a single microlens unit along the workpiece rotation direction; first, the kinematic relationship equation is established , wherein t is the single effective cutting time of the milling cutter on the workpiece, and v is the size of the non-zero relative cutting linear velocity vector in step S3;

[0017] Then, the size of the tangential linear velocity of the milling cutter is defined as a function proportional to the product of the rotational speed and the radius r, and the size of the tangential linear velocity of the workpiece is defined as a function proportional to the product of the rotational speed and the distance R from the cutting position of the milling cutter to the workpiece rotation axis;

[0018] Finally, the function relationship of the above , is substituted into the vector composition relationship in step S3 to represent v, and the rotational speed ratio relationship locked in step S2 is combined to construct the equation group about the rotational speed and solve it simultaneously to obtain the rotational speed of the milling spindle and the rotational speed of the workpiece spindle required to meet the arc length LL.

[0019] As a preferred, in the step S4, the set value of the duration T is: ;

[0020] Through the setting of the duration T, the milling cutter only performs one complete cutting envelope on each microlens unit on the workpiece circumference.

[0021] As a preferred, the milling spindle is an air-floating electric spindle, the set range of the rotational speed is 60000 r / min to 120000 r / min, and the rotational speed control error is kept within 1 r / min;

[0022] The workpiece spindle is an air-floating turntable, and the set range of the rotational speed is 1 r / min to 10000 r / min.

[0023] As preferred, the cutter head of the milling cutter comprises a planar rake face and a spherical flank face; the intersection line of the planar rake face and the spherical flank face constitutes the single cutting edge; the intermittent cutting state of alternation of cutting phase and idle phase between the single cutting edge and the workpiece is formed during the rotation in step S4 by using the geometric asymmetry of the planar rake face and the spherical flank face in the circumferential direction of the milling cutter.

[0024] As preferred, the milling cutter is sprayed with fluid by a nozzle to the cutting edge of the milling cutter to remove chips and reduce cutting heat during the idle phase.

[0025] The application also provides a microlens array forming device based on synchronous rotation of main shafts, comprising:

[0026] A feed drive mechanism configured to provide multi-degree-of-freedom relative displacement motion;

[0027] A workpiece main shaft connected to the feed drive mechanism for clamping and driving the workpiece to rotate;

[0028] A milling main shaft connected to the feed drive mechanism for clamping and driving the milling cutter with a single cutting edge and a spherical rotation envelope to rotate, and the workpiece main shaft and the milling main shaft are distributed at a preset angle;

[0029] A control system in communication connection with the feed drive mechanism, the workpiece main shaft and the milling main shaft, the control system being configured to execute the following control program:

[0030] Controlling the milling cutter to move to a predetermined cutting position of the workpiece; determining the number N of microlens units to be generated in one rotation of the workpiece according to the current cutting position of the workpiece, and locking the rotational speed of the milling main shaft and the rotational speed of the workpiece main shaft to a constant rotational speed ratio, i.e. satisfying the relationship ;

[0031] Driving the workpiece main shaft and the milling main shaft to rotate and controlling the rotation directions of the two, so that at the current cutting position of the milling cutter and the workpiece, the tangential linear velocity vector generated by the rotation of the milling cutter and the tangential linear velocity vector generated by the rotation of the workpiece are vector synthesized, thereby forming a non-zero relative cutting linear velocity vector between the milling cutter and the workpiece at the current cutting position;

[0032] controlling the milling spindle and the workpiece spindle to generate relative cutting feed until the milling cutter cuts into the workpiece to a predetermined cutting depth, and then keeping the cutting depth of the milling cutter unchanged; in this process, the milling spindle and the workpiece spindle are maintained to rotate according to the constant rotational speed ratio and the rotational direction and for a time T, the time T being an integer multiple of a rotational period of the workpiece spindle;

[0033] after the workpiece spindle completes at least one rotation, controlling the milling spindle and the workpiece spindle to generate relative feed motion, so that the milling cutter moves a step along a preset microlens array arrangement direction relative to the workpiece, and repeatedly performing the above control program until a complete microlens array is generated on the workpiece.

[0034] The one or more technical solutions provided in the application have at least the following technical effects or advantages:

[0035] The application establishes constant rotational speed ratio synchronous coupling driving of the milling spindle and the workpiece spindle, utilizes velocity vector synthesis mechanism of an actual cutting contact area, compensates for velocity loss of a rotation center of the milling cutter with high-speed rotation motion of the workpiece, so that even in the case that an intersection (i.e. a geometric dead point) of a spherical rotary envelope surface of the milling cutter and a rotation axis contacts the workpiece, a non-zero relative cutting line velocity vector can be constructed, which physically eliminates material extrusion and plowing defects caused by zero-speed dead zones in the background technology, and ensures that the entire surface of the microlens can reach optical-grade processing quality of Ra < 10nm; meanwhile, the application utilizes high-speed rotation motion envelope forming of the double spindles to replace inefficient reciprocating motion limited by dynamic response frequency of a linear feed shaft in traditional slow tool servo technology, and through rotational speed ratio locking and fixed-axis envelope technology based on parameter inversion, the application completely eliminates the complex point cloud tool path programming burden in the background technology, and improves the processing efficiency of the microlens array by several orders of magnitude compared with traditional technology. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a structural schematic diagram of a microlens array forming device based on synchronous rotation of spindles in an embodiment of the application;

[0037] Figure 2 is Figure 1 is a local enlarged schematic diagram of a cutting contact area of the milling cutter and the workpiece in

[0038] Figure 3 is a structural schematic diagram of a microlens array forming device based on synchronous rotation of spindles in an embodiment of the application;

[0039] Figure 4 is Figure 3 is a local enlarged schematic diagram of a cutting contact area of the milling cutter and the workpiece in

[0040] Figure 5 is a structural schematic view of a tool head of a milling tool in the present application.

[0041] Reference signs: 1, workpiece spindle; 2, workpiece; 3, milling spindle; 4, milling tool; 41, tool head; 411, planar rake face; 412, spherical relief face; 413, single cutting edge. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application. Embodiment one

[0043] Please refer to Figure 1 , Figure 2 and Figure 5 , the present embodiment provides a micro-lens array forming device and method based on synchronous rotation of spindles, mainly applied to machining high-precision micro-lens arrays on the surface of a roll-cylinder-shaped workpiece.

[0044] The micro-lens array forming device based on synchronous rotation of spindles mainly includes a machine tool body, a feed driving mechanism, a workpiece spindle 1, a milling spindle 3, and a control system. Among them, the machine tool body is configured with the feed driving mechanism, which preferably adopts a high-precision X-axis, Y-axis, and Z-axis linear guide rail sliding table combination, which can realize multi-degree-of-freedom relative displacement motion. The workpiece spindle 1 is connected to the feed driving mechanism (for example, mounted on the X-axis sliding table), and the workpiece spindle 1 is used to clamp and drive the workpiece 2 to be machined to rotate around the horizontal axis. The workpiece spindle 1 is preferably a low-speed high-precision air bearing rotary table. The milling spindle 3 is connected to the feed driving mechanism (for example, mounted on the Z-axis sliding table), and the milling spindle 3 is used to clamp and drive the milling tool 4 to rotate around the vertical axis at high speed. The milling spindle 3 is preferably a super-speed air bearing motor spindle with a maximum rotation speed of 120,000 r / min. In the present embodiment, in order to adapt to the roll processing requirements, the rotation axis of the workpiece spindle 1 and the rotation axis of the milling spindle 3 are configured to be in a non-planar vertical state in space, that is, in an orthogonal distribution mode.

[0045] Please refer to Figure 5The milling tool 4 used in the embodiment is a single crystal diamond tool, and the tool head 41 has a specific geometry. Specifically, the tool head 41 is jointly surrounded by a planar rake face 411 and a spherical relief face 412. The planar rake face 411 contains the rotational center axis of the milling tool 4, and the intersection line of the planar rake face 411 and the spherical relief face 412 constitutes the only single cutting edge 413 of the tool. When the milling tool 4 rotates at high speed, the rotational trajectory formed by the single cutting edge 413 in space constitutes a spherical envelope. By utilizing the geometric asymmetry of the planar rake face 411 and the spherical relief face 412 in the circumferential direction of the milling tool 4, the single cutting edge 413 and the workpiece 2 form a high-frequency alternating cycle of cutting phase and idle phase during processing. The microlens array forming device based on synchronous rotation of the spindle can also be configured with a nozzle (not shown in the figure) to spray cold air or a small amount of lubricating oil mist to the cutting edge during the idle phase to efficiently remove chips and reduce cutting heat.

[0046] Based on the above device, the microlens array forming method of the embodiment has the following process:

[0047] 1. Workpiece installation and positioning. The workpiece 2 with a surface plated with nickel in the form of a roller is installed on the workpiece spindle 1, and the control system drives the feed drive mechanism to control the movement of the milling tool 4 to the predetermined cutting position on the cylindrical surface of the workpiece 2.

[0048] 2. Establish synchronous coupling relationship. The control system calculates the number N of microlens units to be generated on the current cutting trajectory during one revolution of the workpiece 2 according to the current cutting position of the milling tool 4 on the workpiece 2 (for a cylindrical roller, the cutting revolution radius corresponding to this position is fixed). Then, the control system establishes an electronic gear relationship to lock the rotational speed of the milling spindle 3 and the rotational speed of the workpiece spindle 1 at a constant speed ratio, i.e., satisfying the relationship . For example, if 550 lenses are to be generated in one revolution of the roller-shaped workpiece 2, the speed ratio is locked at 550:1.

[0049] 3. Drive rotation and eliminate dead zones by vector synthesis. Drive the milling spindle 3 and the workpiece spindle 1 to rotate at the locked ratio, and control the rotation directions of the two. As shown in Figure 2 , in the actual cutting contact area of the milling tool 4 and the workpiece 2, the high-speed rotation of the milling tool 4 generates a tangential linear velocity vector , and the rotation of the workpiece 2 generates a tangential linear velocity vector In the orthogonal distribution mode, the two vectors are orthogonal or intersected at the cutting contact position. The present application utilizes the principle of vector composition to compensate the speed deficiency of the milling cutter 4 at the rotation center by means of the high-speed rotating motion of the workpiece 2. Therefore, even at the intersection point of the spherical envelope surface of the milling cutter 4 and the rotation axis (i.e. the geometric dead point), a non-zero relative cutting linear velocity vector v can be formed by vector superposition, thus avoiding the material extrusion and plowing phenomenon from the physical principle.

[0050] 4. Perform the fixed-axis envelope forming. Control the relative cutting feed of the milling spindle 3 relative to the workpiece spindle 1 until the milling cutter 4 cuts into the workpiece 2 to the predetermined cutting depth. At this time, keep the radial cutting depth of the milling cutter 4 unchanged, i.e. lock the position of the feed axis. In this state, maintain the constant speed ratio and rotation direction as mentioned above and continue for a predetermined time T. The predetermined time T is set as an integer multiple of the rotation period of the workpiece spindle 1 (for example During this period, the spherical envelope surface formed by the rotation of the milling cutter 4 and the rotating surface of the workpiece 2 have relative motion envelope, and N microlens units are generated on the circumference of the roller-shaped workpiece 2 at one time. Since the dwell time T strictly matches the rotation period, it is ensured that the topography of each lens unit is closed and has no tool marks.

[0051] 5. Perform the array step cycle. After the workpiece spindle 1 completes at least one rotation and forming, control the relative feed motion of the feed drive mechanism to make the milling cutter 4 move a step distance along the preset microlens array arrangement direction (for example along the roller axis direction) relative to the workpiece 2. Then, repeat the above parameter locking and forming steps until a complete microlens array is generated on the surface of the workpiece 2. Example Two

[0052] Please refer to Figure 3 and Figure 4 , this embodiment shows the case of machining microlens array on a planar substrate workpiece. The main difference from Example One is the spatial arrangement mode and the vector composition method.

[0053] In this embodiment, the workpiece 2 is a planar substrate, which is installed on the vertically arranged workpiece spindle 1. In order to meet the best cutting conditions and avoid the dead zone, the rotation axis of the workpiece spindle 1 and the rotation axis of the milling spindle 3 are configured in a non-parallel inclined state (i.e. inclined distribution mode), for example, the milling spindle 3 is deflected by an inclination angle .

[0054] As shown in Figure 4 , due to the inclination angle Due to the presence of [something], the effective cutting position of the milling cutter 4 deviates from its geometric vertex, utilizing the effective cutting edge on the side of the cutter head 41 for cutting. At this time, in the projection direction of the cutting contact plane, the rotation direction of the workpiece spindle 1 and the milling cutter 4 is controlled, causing the tangential linear velocity vector generated by the milling cutter 4 to [something]. The tangential linear velocity vector generated by workpiece 2 The directions are the same, and they satisfy... By vector subtraction ( This creates a stable climb milling state, which not only eliminates dead zones but also avoids vibrations caused by conventional milling, further improving surface finish.

[0055] Furthermore, in planar helical or concentric circle array machining, the cutting trajectory radius R of workpiece 2 continuously changes as the machining position moves from the outer circle to the center. Therefore, after each movement step, the control system recalculates the number N of microlens units required for that revolution based on the current cutting radius R and relocks the speed ratio. This is to ensure that the size of the microlenses remains consistent at different radii. Example 3

[0056] This embodiment provides a detailed explanation of the parameter inverse calculation logic in the above method that eliminates the need to generate point cloud toolpaths. This method allows the operator to directly deduce control parameters based on the geometry of the target microlens.

[0057] Specifically, the inverse parameter calculation steps include:

[0058] The first step is to determine the cutting depth based on the unit width. The maximum surface width LW of the target single microlens unit along the workpiece 2 axis is obtained. The control system, based on the radius r of the spherical rotational envelope of the milling tool 4, uses geometric formulas... It automatically calculates the required predetermined cutting depth d in reverse and uses it as the target value for the feed control of workpiece spindle 1 and milling spindle 3.

[0059] The second step involves determining the rotational speed based on the unit length. The maximum arc length LL of the surface of a single target microlens unit along the rotational direction of workpiece 2 is obtained. First, the kinematic equations are established. Where t is the single effective cutting time of the milling tool 4 on the workpiece 2, and v is the magnitude of the non-zero relative cutting linear velocity vector mentioned in step S3. Next, the conversion relationship between linear velocity and rotational speed is introduced, namely the tool tangential linear velocity. With rotational speed The tangential linear velocity of the workpiece is directly proportional to the radius r. With rotational speed This is directly proportional to the distance R from the cutting position to the workpiece's rotation axis. Finally, this is combined with the locked speed ratio relationship. And the vector synthesis rule in the embodiment one or the embodiment two, construct equation group and solve simultaneously, thus obtain the main shaft rotating speed satisfying the arc length LL requirement And Instruction value.

[0060] Experiments show that the method and device of the application can process 550 microlens units on the surface of a nickel-plated roller in only about 9.6 seconds, while the traditional single-point diamond turning technology needs about 10 hours and the traditional micro-milling needs about 1 hour. The white light interferometer detection shows that the surface roughness Ra of the obtained microlens array is less than 10 nm, and there is no obvious extrusion or plowing mark in the lens center, which verifies the significant advantages of the application in efficiency and quality.

[0061] The above merely illustrates the specific embodiments of the application, but the protection scope of the application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the application, which should be covered in the protection scope of the application.

Claims

1. A microlens array forming method based on synchronous rotation of main shafts, characterized by, The method comprises the following steps: S1, mounting a workpiece (2) to be processed on a workpiece spindle (1), mounting a milling cutter (4) with a single cutting edge and a spherical rotation envelope surface on a milling spindle (3), and configuring the workpiece spindle (1) and the milling spindle (3) to be distributed at a preset angle, then controlling the milling cutter (4) to move to an initial cutting position of the workpiece (2); S2, according to the current cutting position of the workpiece (2), determine the number N of microlens units to be generated on the current cutting track in one rotation of the workpiece (2), and lock the rotating speed of the milling spindle (3) to a constant speed ratio, i.e. the rotating speed of the workpiece spindle (1) ; and ; S3, driving the workpiece spindle (1) and the milling spindle (3) to rotate and controlling the rotation directions of the two, so that at the current cutting position of the milling cutter (4) and the workpiece (2), the tangential linear velocity vector generated by the rotation of the milling cutter (4) and the tangential linear velocity vector generated by the rotation of the workpiece (2) are vector synthesized, thereby forming a non-zero relative cutting linear velocity vector between the milling cutter (4) and the workpiece (2) at the current cutting position; S4, controlling the milling spindle (3) and the workpiece spindle (1) to generate relative cutting feed until the milling cutter (4) cuts into the workpiece (2) to a predetermined cutting depth, then keeping the cutting depth of the milling cutter (4) unchanged, and directly generating the geometric morphology of the microlens unit on the workpiece (2) by using the relative motion envelope of the spherical rotary envelope surface formed by the rotation of the milling cutter (4) and the rotating surface of the workpiece (2); during this process, the milling spindle (3) and the workpiece spindle (1) are maintained to rotate according to the speed ratio in step S2 and the rotation direction in step S3 for a time T, and the time T is an integer multiple of the rotation period of the workpiece spindle (1); S5, after the workpiece spindle (1) completes at least one rotation, controlling the milling spindle (3) and the workpiece spindle (1) to generate relative motion, so that the milling cutter (4) moves one step along the preset microlens array arrangement direction relative to the workpiece (2); S6, repeating steps S2 to S5 until a complete microlens array is generated on the workpiece (2).

2. The method of claim 1, wherein, The preset angle distribution in step S1 and the vector synthesis in step S3 are configured according to the type of the workpiece (2) as one of the following two modes: When the workpiece (2) is a rotary body roller, the rotation axis of the workpiece spindle (1) and the rotation axis of the milling spindle (3) are configured to be in a spatially non-planar vertical state, the linear velocity vectors of the milling cutter (4) and the workpiece (2) are in an orthogonal state at the cutting contact position, and the non-zero relative cutting linear velocity vector is formed by vector superposition; When the workpiece (2) is a planar substrate, the rotation axis of the workpiece spindle (1) and the rotation axis of the milling spindle (3) are configured to be in a non-parallel inclined state, so that the projections of the linear velocity vectors of the milling cutter (4) and the workpiece (2) on the cutting contact plane are in the same direction, and the linear velocity vector of the milling cutter (4) is greater than the linear velocity vector of the workpiece (2), and the non-zero relative cutting linear velocity vector is formed by subtracting the linear velocity vector of the workpiece (2) from the linear velocity vector of the milling cutter (4).

3. The method of claim 1, wherein, the number N of the microlens units in the step S2, the rotational speed of the milling spindle (3) the rotational speed of the workpiece spindle (1) The determination of the rotational speed of the workpiece spindle (1) comprises the following steps: Step one, obtain the surface maximum width LW of single microlens unit along the workpiece (2) axial direction; and according to the radius r of the spherical rotary envelope surface of the milling cutter (4), the cutting depth d required for the milling cutter (4) to process the microlens unit is reversely calculated by using the following geometric relationship: ; Step two, get the maximum surface arc length LL of the single microlens unit along the rotation direction of the workpiece (2); first, establish the kinematics relationship equation wherein t is the single effective cutting time of the milling cutter (4) on the workpiece (2), and v is the magnitude of the non-zero relative cutting line speed vector in step S3. Then the magnitude of the tangential linear velocity of the milling tool (4) is defined as a function proportional to the product of the rotational speed and the radius r, the magnitude of the tangential linear velocity of the workpiece (2) is defined as a function proportional to the product of the rotational speed and the distance R of the cutting position of the milling tool (4) to the rotational axis of the workpiece (2); Finally, the functional relationship of the above , is substituted into the vector composition relationship described in step S3 to represent v, and the locked speed ratio relationship in step S2 is combined to construct an equation group about the speed and is solved simultaneously, so that the speed of the milling spindle (3) and the speed of the workpiece spindle (1) required to satisfy the arc length LL are obtained.

4. The method of claim 1, wherein, In the step S4, the set value of the time T is: ; By setting the time T, the milling cutter (4) is only allowed to perform one complete cutting envelope on each microlens unit on the circumference of the workpiece (2).

5. The method of claim 1, wherein, The milling spindle (3) is an aerostatic electric spindle, whose rotation speed is set in the range from 60 000 r / min to 120 000 r / min, and whose rotation speed control error is kept within 1 r / min. The workpiece spindle (1) is an air floating turntable, whose rotating speed is set in the range of 1 r / min to 10000 r / min.

6. The method of claim 1, wherein, The milling cutter (4) includes a planar rake face and a spherical flank face; the planar rake face contains the center axis of the milling cutter (4), and the intersection line of the planar rake face and the spherical flank face constitutes the single cutting edge; by using the geometric asymmetry of the planar rake face and the spherical flank face in the circumferential direction of the milling cutter (4), an intermittent cutting state of alternating cutting phase and idle phase is formed between the single cutting edge and the workpiece (2) during the rotation in step S4.

7. The method of claim 6, wherein, During the idle phase of the milling cutter (4), a nozzle is used to spray fluid to the cutting edge of the milling cutter (4) to remove chips and reduce cutting heat.

8. A microlens array shaping device based on synchronous rotation of main shafts, characterized by, Comprise: a feed drive mechanism configured to provide multi-degree-of-freedom relative displacement motion; a workpiece spindle (1) connected to the feed drive mechanism for clamping and driving the workpiece (2) to rotate; a milling spindle (3) connected to the feed drive mechanism for clamping and driving the milling cutter (4) with a single cutting edge and a spherical rotation envelope to rotate, and the workpiece spindle (1) and the milling spindle (3) are arranged at a preset angle; a control system in communication with the feed drive mechanism, the workpiece spindle (1) and the milling spindle (3), and the control system is configured to execute the following control program: controlling the milling tool (4) to move to a predetermined cutting position of the workpiece (2); determining the number N of microlens units to be generated in one rotation of the workpiece (2) according to the current cutting position of the workpiece (2), and locking the rotation speed of the milling spindle (3) to a constant speed ratio, i.e. satisfying the relationship and the rotation speed of the workpiece spindle (1) is locked to a constant speed ratio, i.e. satisfying the relationship ​ drive the workpiece spindle (1) and the milling spindle (3) to rotate and control the rotation directions of the two, so that at the current cutting position of the milling cutter (4) and the workpiece (2), the tangential linear velocity vector generated by the rotation of the milling cutter (4) and the tangential linear velocity vector generated by the rotation of the workpiece (2) are vector synthesized, thereby forming a non-zero relative cutting linear velocity vector between the milling cutter (4) and the workpiece (2) at the current cutting position; control the relative cutting feed of the milling spindle (3) and the workpiece spindle (1) until the milling cutter (4) cuts into the workpiece (2) to a predetermined cutting depth, and then keeps the cutting depth of the milling cutter (4) unchanged; during this process, the milling spindle (3) and the workpiece spindle (1) are maintained to rotate at the constant speed ratio and the rotation direction and for a time T, and the time T is an integer multiple of the rotation period of the workpiece spindle (1); after the workpiece spindle (1) completes at least one rotation, control the relative feed motion of the milling spindle (3) and the workpiece spindle (1) to move the milling cutter (4) relative to the workpiece (2) by one step in the preset microlens array arrangement direction, and repeat the above control program until a complete microlens array is generated on the workpiece (2).

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