TWI416291B - Method for processing an aspheric lens mold - Google Patents

Abstract

The invention provides a method for processing an aspheric lens mold, The method includes the following steps: providing a processing equipment for processing a mold, fixing the mold on a main axis of the processing equipment; driving a knife of the processing equipment to the zero point position of a workpiece coordinate; a numerical control unit of the processing equipment transforms a polar coordinates value of the knife to a workpiece coordinate value, and determines the working point on the mold for the knife; the numerical control unit gets the workpiece coordinate value of a mold hole's the geometric center according to the workpiece coordinate value of the knife, calculating the face shape of the mold hole by according to the polar coordinates value of the knife and the workpiece coordinate value of geometric center of the mold hole and an aspheric formula, and determining immediate feeding quantity of the knife; Supplements emendation to the cutting tool way according to the mold hole's face shape, completes the process of the aspheric surface lens mold.

Description

Aspheric lens mold processing method

The invention relates to a processing method, in particular to a method for processing an aspherical lens mold.

The molds in the optical part injection molding technology have to meet high requirements and cannot be achieved by general mechanical processing methods. At present, most foreign mold manufacturers use ultra-precision single-point diamond lathes for turning or grinding, and then use diamond polishing paste for manual polishing to process the mold surface (see "Manufacture of aspherical lens molds", Zhang Song," Recording Media Technology, No. 6, 2007, pp. 62-64), but this method is inefficient and is not conducive to mass production of aspheric lens molds. However, other methods, such as EDM, electroforming, and optical grinding, have low processing accuracy, so processing of aspherical lens molds becomes very difficult.

In view of this, it is necessary to provide an aspherical lens mold processing method with high processing precision and high processing efficiency.

An aspherical lens mold processing method, comprising the steps of: providing a processing device for processing a mold to be processed, fixing the mold to be processed on a main shaft of the processing device, the spindle driving the processing mold to rotate; driving the processing device The tool enters the origin position of the workpiece coordinate system; the numerical control unit of the processing device takes the pole of the tool The standard value is converted into the workpiece coordinate value, and the machining point of the tool on the mold to be processed is determined; the numerical control unit is worth according to the workpiece coordinate of the tool, and the coordinate value of the geometric center workpiece of one of the mold holes to be processed is obtained, and the polar coordinate value of the tool is The geometric center of the cavity is substituted into the aspherical surface formula to calculate the surface shape of the mold cavity to be processed, and the instantaneous feed amount of the tool is determined; the tool path is corrected according to the shape of the mold cavity to be processed, and the completion is completed. Processing of aspheric lens molds.

Compared with the prior art, the aspherical lens mold processing method obtains the aspherical mold cavity surface shape by the aspherical surface type formula, and then drives the tool to perform the cutting according to the aspherical surface type to process the mold, which can effectively improve the processing. Accuracy and productivity.

1 is a flow chart of a method for processing an aspherical lens mold according to an embodiment of the present invention; FIG. 2 is a schematic view of a processing device for processing an aspherical lens mold according to an embodiment of the present invention; and FIG. 3 is a schematic view showing a principle of a method for processing an aspherical lens mold according to an embodiment of the present invention.

The technical solution will be further described in detail below with reference to the accompanying drawings and embodiments.

As shown in FIG. 1 and FIG. 2, the aspherical lens mold processing method of the present invention comprises the following steps:

S101, a processing device is provided for processing the mold 100 to be processed, and the mold 100 to be processed is fixed on the main shaft 22 of the processing device, and the spindle 22 drives the mold 100 to be processed to rotate. The aspherical lens mold processing device further includes: a numerical control device 10, a cutter 12, a piezoelectric drive shaft 14, a Z-axis guide rail 16, and an electric Machine 20, an X-axis guide rail 24. A fixed piezoelectric drive shaft 14 is mounted on the Z-axis guide 16. A cutter 12 is fixed to one end of the piezoelectric drive shaft 14 with respect to the mold 100 to be processed. The cutter 12 is a diamond cutter head and has strong wear resistance. An X-axis guide rail 24 is disposed in a direction perpendicular to the Z-axis guide rail 18. A motor 20 is disposed on the X-axis guide rail 24, and a driving device is driven in the X-axis guide rail 24 to drive the motor 20 to move in the X-axis direction to be processed. The mold 100 is transformed by the machining point. Inside the motor 20 is a spindle 22 that drives the mold for rotation.

The contact point between the tool 12 and the mold to be processed 100 is defined as the center point of the tool 12, and the center point of the tool 12 is in the polar coordinate system with the origin of the workpiece coordinate system as the pole point, and the positive direction of the X coordinate of the workpiece coordinate system is the polar axis. The polar coordinate value is (ρ, θ), and the workpiece coordinate system adopts a standard right-handed Cartesian Cartesian coordinate system, which conforms to the right-hand rule, and the coordinate value of the workpiece after the transformation of the polar coordinate value (ρ, θ) of the tool 12 is (Xm, Ym); the geometric center point of each cavity 100 has a coordinate value (Xn, Yn) in the workpiece coordinate system.

S102, the tool 12 that drives the processing device enters the origin position of the workpiece coordinate system. At this time, the pole coordinate value of the tool 12 is (0, 0). When the spindle 22 is rotated and the motor 20 on the X-axis rail 24 is moved, the polar coordinate value of the tool 12 changes.

S103, during the machining process, the numerical control device 10 converts the polar coordinate value of the tool 12 into a workpiece coordinate value, Xm = ρ cos θ , Ym = ρ sin θ , where Xm is the abscissa value of the tool 12 in the workpiece coordinate system, Ym is the ordinate value of the tool 12 in the workpiece coordinate system, ρ is the polar diameter of the tool 12 in the polar coordinate system, and θ is the polar angle of the tool 12 in the polar coordinate system. The numerical control device 10 determines the machining point of the tool 12 on the mold to be processed 100 based on the workpiece coordinate value of the tool 12.

S104, when the tool 12 enters the cavity 101 area of the mold 100 to be processed, the numerical control device 10 obtains the cavity 101 of the mold to be processed 100 by comparing the workpiece coordinate value of the tool 12 with the workpiece coordinate value range of the cavity 101. Geometric center coordinate value (Xn, Yn). As shown in FIG. 3, when the mold 100 to be processed is continuously rotated, the cutter 12 passes through the processing point A and the processing point B of two different workpiece coordinate values on the cavity 101, and the polar coordinate value of the cutter 12 changes during this process. The numerical control device 10 continuously converts the polar coordinate value of the tool 12 into the workpiece coordinate value. When the tool 12 passes the machining point A, the workpiece coordinate value of the converted tool 12 is the workpiece coordinate value of the machining point A. Similarly, when the tool 12 After the processing point B, the workpiece coordinate value of the converted tool 12 is the workpiece coordinate value of the processing point B, and each workpiece coordinate value after the conversion of the tool 12 corresponds to the processing point on the mold 100 to be processed; The device 10 compares the workpiece coordinate value of the tool 12 with the workpiece coordinate value range of the cavity 101, and determines the processing range of which cavity 101 the tool 12 has entered, and the geometric center coordinate value of the cavity 101. The numerical control device 10 can accurately calculate the infeed amount of the tool 12 according to the geometric center coordinate value (Xn, Yn) of the cavity 101, the polar coordinate value (ρ, θ) of the tool 12, and an aspherical surface type formula.

Aspherical surface formula:

Wherein, Z is a plane perpendicular to the optical axis and passing through the optical center of the lens as a reference surface, and a displacement value in the vertical direction from the optical axis is R along the optical axis direction, C is a radius of curvature, R is a lens height, and K is a cone Coin Constant, Ai is the second time I-th order Aspherical Coefficient.

The aspheric height value (2) By substituting the formula (2) into the formula (1) to obtain an aspherical surface type formula which is all composed of known quantities, the numerical control device 10 according to the polar coordinate value of the tool 12 and the geometry of the cavity 101 of the mold 100 to be processed The central coordinate value is used to calculate the aspherical surface of the cavity 101, and the piezoelectric drive shaft 14 is driven to respond quickly, and the cutter 12 is driven to cut the cavity 101 according to the aspherical surface shape, which drives the piezoelectric drive shaft 14 The maximum moving frequency is 400HZ and the maximum moving distance is 70um. By calculating the aspherical surface of the cavity 101, the amount of the tool 12 is determined, and the piezoelectric drive shaft 14 has a relatively fast moving frequency and a large moving distance, which can effectively reduce the response time of the tool 12. Improve cutting accuracy. In this embodiment, by setting the response frequency of the piezoelectric drive shaft 14, the control tool 12 can automatically retract after processing a certain point of the cavity 101 for a certain period of time, ready to process the next point, through a certain point. The secondary feed is completed and processed.

S105, the machining precision can be further improved by the path correction method, because the cutter head of the cutter 12 is not infinitely small, and there is a certain radius, when the cutting point of the cutter head is in contact with the cavity 101 of the mold 100 to be processed. A method in which the point around the cutter head may interfere with the cavity 101 to cause the shape accuracy to deteriorate, and the cutter 12 path is optimized. The path correction method is to calculate the point around the cutter head through the aspherical surface formula to determine the amount of the tool 12 to determine whether there will be interference. When there is a point around the cutter head, the height is smaller than the aspheric surface type. The corresponding height indicates that there is interference, so it is based on each The point of maximum interference is retracted, and the amount of interference is the difference between the height of the periphery of the cutter head and the height of the opposite point on the aspherical surface. By detecting the interference amount, the cutting point where there is no interference at each point on the cutter head can be selected to cut the position where the interference exists before, and the path precision can be effectively improved by correcting the path of the cutter 12.

The aspherical surface can be processed by the method, and the processing precision and processing efficiency of the aspherical mold can be effectively improved.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

Claims (4)

An aspherical lens mold processing method, comprising the steps of: providing a processing device for processing a mold to be processed, fixing the mold to be processed on a main shaft of the processing device, the spindle driving the processing mold to rotate; driving the processing device The tool enters the origin position of the workpiece coordinate system; the numerical control unit of the processing device converts the polar coordinate value of the tool into the workpiece coordinate value, and determines the machining point of the tool on the mold to be processed; the numerical control unit is worthy of processing according to the workpiece coordinate of the tool The geometric center workpiece coordinate value of one of the mold holes is calculated by substituting the polar coordinate value of the tool and the geometric center workpiece coordinate value of the cavity into the aspherical surface formula to calculate the shape of the mold cavity to be processed, and determining the instant of the tool. The amount of feed; the point around the cutter head is calculated by the aspherical surface formula to determine the amount of tool feed, and it is judged whether there will be interference phenomenon. When there is a point around the cutter head, the height is smaller than the aspherical surface type. The height indicates the presence of interference, so the retraction is performed according to the maximum amount of interference at each point on the cutter head. The amount of interference is the difference between the height of the periphery of the cutter head and the height of the opposite point on the aspherical surface type; by detecting the amount of interference, a point where there is no interference at each point on the cutter head can be selected for the position where the interference exists previously. Cutting, completing the processing of the aspherical lens mold. The method for processing an aspherical lens mold according to claim 1, wherein: the workpiece coordinate system adopts a standard right-handed Cartesian rectangular coordinate system, which conforms to a right-hand rule; and the polar coordinate system uses an origin as a pole to the workpiece. The positive direction of the X-axis of the coordinate system is the polar axis. The method for processing an aspherical lens mold according to claim 1, wherein: the coordinate value of the tool is converted into a workpiece coordinate value by a formula Xm = ρ cos θ , Ym = ρ sin θ , wherein Xm and Ym are respectively a tool in the workpiece The horizontal and vertical coordinate values in the coordinate system, ρ is the polar diameter of the tool in the polar coordinate system, and θ is the polar angle of the tool in the polar coordinate system. The aspherical lens mold processing method according to claim 1, wherein: the lens height value in the aspherical surface formula Where Xm and Ym are the horizontal and vertical coordinate values of the tool in the workpiece coordinate system, and Xn and Yn are the horizontal and vertical coordinate values of the geometric center of each cavity to be processed in the workpiece coordinate system.