CN109202602B

CN109202602B - Method for polishing non-spherical mold insert

Info

Publication number: CN109202602B
Application number: CN201811103039.0A
Authority: CN
Inventors: 龙青松
Original assignee: CDGM Glass Co Ltd
Current assignee: Chengdu Guangming South Optical Technology Co.,Ltd.
Priority date: 2018-09-20
Filing date: 2018-09-20
Publication date: 2020-03-17
Anticipated expiration: 2038-09-20
Also published as: CN109202602A

Abstract

The invention belongs to the field of mold core surface polishing, and particularly discloses a method for polishing an aspheric mold core, which can ensure that the surface roughness of the aspheric mold core reaches the requirement that Ra is less than or equal to 0.003 when the method is used for polishing the aspheric mold core. The method controls the rotating speed of polishing rotating equipment step by step, and adopts diamond pastes with different particle sizes to sequentially perform rough polishing, semi-finish polishing and finish polishing on the ultraprecisely processed aspheric surface mold core at different rotating speeds, so that the surface quality of the aspheric surface mold core finally reaches 20-10 or more, no scratch point exists when the surface quality is observed under a 50-fold microscope, and the standard that the surface roughness requirement of the aspheric surface mold core reaches Ra less than or equal to 0.003 is met.

Description

Method for polishing non-spherical mold insert

Technical Field

The invention belongs to the field of mold core surface polishing, and particularly relates to a method for polishing an aspheric mold core.

Background

With the widespread use of aspheric optical glass imaging, the requirements for the appearance quality of aspheric lenses are higher and higher, so the surface polishing quality of aspheric mold cores is also improved correspondingly, and particularly, the requirements for the surface roughness of the mold cores of mirror surfaces and mold cores with high-brightness surfaces are higher, so the requirements for polishing are also higher. Polishing is an important process in the manufacturing process of the aspheric surface mold core, not only can the attractiveness of the mold core be improved, but also the corrosion resistance, the wear resistance and the film coating performance of the surface of a material can be improved, and the subsequent lens profiling can be facilitated, such as the service life of a film layer is prolonged, and the mold repairing period is shortened.

Surface polishing generally requires only obtaining a bright surface to remove machining marks. However, the polishing in the glass mold processing is very different from the surface polishing required in other industries, and strictly speaking, the polishing of the mold core should be called super mirror finishing. It places high demands not only on the polishing itself but also on the surface roughness, smoothness and PV accuracy.

At present, the requirement on the surface roughness of an aspheric mold core is up to the standard that Ra is less than or equal to 0.003, the geometric accuracy of parts is difficult to control by methods such as fluid polishing and the like, and the surface quality of methods such as chemical polishing, ultrasonic polishing, magnetic grinding and polishing cannot meet the requirement, so the mirror finishing of a precision mold is mainly mechanical polishing. Mechanical polishing is a polishing method for obtaining a smooth surface by removing polished convex parts through plastic deformation of the surface of a cutting or grinding material, and a super-finishing method can be adopted generally when the requirement on surface quality is high. The ultra-precision polishing is to use a special grinding tool to press tightly on the surfaces of a tool and a mold core in polishing paste containing abrasive materials to rotate. The surface roughness of Ra0.008 mu m can be achieved by the method, which is the highest among various polishing methods at present, and the optical lens mould core is polished by the method; however, it still cannot meet the requirement of Ra ≦ 0.003.

Disclosure of Invention

The invention provides a method for polishing an aspheric mold insert, which can ensure that the surface roughness of the aspheric mold insert reaches the requirement that Ra is less than or equal to 0.003 when the method is used for polishing the aspheric mold insert.

The technical scheme adopted by the invention for solving the technical problems is as follows: the method for polishing the aspherical mold insert comprises a preparation step of clamping the ultraprecisely processed aspherical mold insert to a polishing rotary device, and further comprises the following steps:

step one, controlling the rotating speed of polishing rotating equipment at 160-200 rpm, and polishing by adopting No. 1 diamond paste to slide outwards from the center of an aspheric surface mold core until the surface quality reaches 60-40 or more;

step two, controlling the rotating speed of polishing rotating equipment at 40-100 rpm, and performing semi-finish polishing on the aspheric surface mold core by using No. 1/2 diamond gypsum until the surface quality reaches 40-20 or above;

and step three, controlling the rotating speed of the polishing rotating equipment to be 20-30 rpm, and performing finish polishing on the aspheric surface mold core by adopting No. 1/4 diamond gypsum until the surface quality reaches 20-10 or above.

Further, a cork stick is used to assist polishing.

Further, in the third step, the load applied to the aspheric mold insert is 50-100 g/cm²。

Further, the polishing rotating device is a rotary polishing machine or a grinding machine.

The invention has the beneficial effects that: the method controls the rotating speed of polishing rotating equipment step by step, and adopts diamond pastes with different particle sizes to sequentially perform rough polishing, semi-finish polishing and finish polishing on the ultraprecisely processed aspheric surface mold core at different rotating speeds, so that the surface quality of the aspheric surface mold core finally reaches 20-10 or more, no scratch point exists when the surface quality is observed under a 50-fold microscope, and the standard that the surface roughness requirement of the aspheric surface mold core reaches Ra less than or equal to 0.003 is met.

Detailed Description

The method for polishing the aspherical mold insert comprises a preparation step of clamping the ultraprecisely processed aspherical mold insert to a polishing rotary device, and further comprises the following steps:

step one, controlling the rotating speed of polishing rotating equipment at 160-200 rpm, and polishing by adopting No. 1 diamond paste to slide outwards from the center of an aspheric surface mold core until the surface quality reaches 60-40 or more; observing the surface of the aspheric surface mold core under a 50-time microscope without obvious processing traces; the step generally takes 5 to 7 minutes;

step two, controlling the rotating speed of polishing rotating equipment at 40-100 rpm, and performing semi-finish polishing on the aspheric surface mold core by using No. 1/2 diamond gypsum until the surface quality reaches 40-20 or above; observing the surface of the aspheric surface mold core under a 50-time microscope without processing traces completely; the step generally takes 8 to 20 minutes;

step three, controlling the rotating speed of polishing rotating equipment at 20-30 rpm, and performing finish polishing on the aspheric surface mold core by using No. 1/4 diamond gypsum until the surface quality reaches 20-10 or above; observing the surface of the aspheric surface mold core under a 50-time microscope without scratches and spots completely; this step generally takes 20 to 30 minutes.

The polishing by the method belongs to precise polishing and is necessarily carried out in an absolutely clean space. Dust, smoke, dandruff and oral spray can all potentially scrap a high precision polished surface obtained after several hours of operation. When using diamond paste for abrasive polishing, not only is the work surface required to be clean, but the hands of the worker must also be carefully cleaned.

The polishing rotating equipment is used for driving the aspheric surface mold core to rotate so as to polish the aspheric surface mold core; the polishing rotating device may be various, and is preferably a rotary polishing machine or a grinder. The diamond gypsum is a mixture of fine diamond particles and an oily binder; diamond paste #1 shows a mixture of diamond particles having a particle size of 1 μm and a binder, diamond paste #1/2 shows a mixture of diamond particles having a particle size of 0.5 μm and a binder, and diamond paste #1/4 shows a mixture of diamond particles having a particle size of 0.25 μm and a binder. Surface quality standards 60-40, 40-20, 20-10 are U.S. military standards, with numbers in front of the numbers indicating scratch allowed maximum values and numbers behind indicating dot allowed maximum values; see in particular U.S. military Standard MIL-PRF-13830B for blemish criteria.

In order to facilitate polishing, a cork rod is usually adopted to assist polishing in the process of polishing the aspheric mold core by using the method. When the aspheric surface or the spherical surface is polished, the radian of the round surface and the radian of the spherical surface can be better matched by using the cork stick. The used cork stick usually needs to be trimmed, and the end of the cork stick is generally trimmed to keep the end of the cork stick to be matched with the shape of the surface of the aspheric mold core, so that the sharp angle of the cork stick can be prevented from contacting the surface of the aspheric mold core to cause deep scratch.

Polishing must be performed under a light pressure as much as possible, especially when fine diamond gypsum is used for polishing, so as to ensure that the surface pressure of the aspheric surface mold core is not too high, and the surface type PV of the aspheric surface mold core is not damaged. In the third step, the load applied to the aspheric mold insert is 50-100 g/cm for better surface quality²。

Example 1

The method of the invention is adopted to polish an aspheric mold core with the diameter phi 15.

Firstly, clamping an ultraprecisely processed aspheric mold core on a workbench of a rotary polishing machine;

then, controlling the rotating speed of the rotary polishing machine at 200rpm, adopting No. 1 diamond paste to slide and polish the aspheric surface mold core outwards from the center of the aspheric surface mold core for 5 minutes, observing that no obvious processing trace exists on the surface of the aspheric surface mold core under a 50-time microscope after polishing, and enabling the surface quality to reach 60-40;

then, controlling the rotating speed of the rotary polishing machine at 80rpm, polishing the surface of the aspheric mold core for 10 minutes by using No. 1/2 diamond paste, and observing that the surface of the aspheric mold core has no processing trace completely under a 50-time microscope after polishing, wherein the surface quality reaches 40-20;

finally, the rotational speed of the polishing rotary device was controlled at 30rpm, and 50g/cm of #1/4 diamond gypsum was used²The surface of the aspheric mold core is polished for 20 minutes under the load, and after polishing, no scratch and point are observed on the surface of the aspheric mold core completely under a 50-fold microscope, and the surface quality reaches 20-10.

The surface roughness Ra of the polished aspheric surface mold core is 0.002, and the standard that the Ra is less than or equal to 0.003 is met.

Example 2

then, the rotating speed of the rotary polishing machine is controlled at 160rpm, No. 1 diamond paste is adopted to slide and polish the aspheric surface mold core outwards from the center of the aspheric surface mold core for 7 minutes, no obvious processing trace is observed on the surface of the aspheric surface mold core under a 50-time microscope after polishing, and the surface quality reaches 60-40;

then, controlling the rotating speed of the rotary polishing machine at 50rpm, polishing the surface of the aspheric mold core for 16 minutes by adopting No. 1/2 diamond paste, and observing that the surface of the aspheric mold core has no processing trace completely under a 50-time microscope after polishing, wherein the surface quality reaches 40-20;

finally, the rotational speed of the polishing rotating device is controlled at 20rpm, and 80g/cm of No. 1/4 diamond paste is adopted²The surface of the aspheric mold core is polished for 30 minutes under the load, and no scratch or point is observed on the surface of the aspheric mold core completely under a 50-fold microscope after polishing, and the surface quality reaches 20-10.

Example 3

then, controlling the rotating speed of the rotary polishing machine at 180rpm, adopting No. 1 diamond paste to slide and polish the aspheric surface mold core outwards from the center of the aspheric surface mold core for 6 minutes, observing that no obvious processing trace exists on the surface of the aspheric surface mold core under a 50-time microscope after polishing, and enabling the surface quality to reach 60-40;

then, controlling the rotating speed of the rotary polishing machine at 100rpm, polishing the surface of the aspheric mold core for 17 minutes by using No. 1/2 diamond paste, and observing that the surface of the aspheric mold core has no processing trace completely under a 50-time microscope after polishing, wherein the surface quality reaches 40-20;

finally, the rotational speed of the polishing rotating device is controlled at 25rpm, and the No. 1/4 diamond paste is adopted at 100g/cm²The surface of the aspheric mold core is polished for 24 minutes under the load, and after polishing, the surface of the aspheric mold core is observed to have no scratch and point under a 50-fold microscope, and the surface quality reaches 20-10.

Claims

1. A method for polishing an aspherical mold insert, which comprises a preparatory step of clamping an ultraprecisely machined aspherical mold insert to a polishing rotary apparatus, characterized by further comprising the steps of:

2. The method of claim 1, wherein the step of polishing the mold insert comprises: and (4) polishing by using a cork rod.

3. The method according to claim 1 or 2, wherein: in the third step, the load applied to the aspheric mold insert is 50-100 g/cm²。

4. The method of claim 3, wherein the step of polishing the aspheric mold insert comprises: the polishing rotating equipment is a rotary polishing machine or a grinding machine.