CN115673881A - High-finish polishing method for medium and small-caliber germanium windows - Google Patents
High-finish polishing method for medium and small-caliber germanium windows Download PDFInfo
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- CN115673881A CN115673881A CN202211339503.2A CN202211339503A CN115673881A CN 115673881 A CN115673881 A CN 115673881A CN 202211339503 A CN202211339503 A CN 202211339503A CN 115673881 A CN115673881 A CN 115673881A
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Abstract
The invention belongs to the technical field of germanium window processing, and particularly relates to a high-finish polishing method for a medium and small-caliber germanium window, which comprises the following processing process routes: fine grinding → rough polishing → fine polishing → polishing on the disk → polishing under the disk. Compared with the prior art, the invention has the following beneficial effects: the invention provides a polishing process combining on-disc polishing and off-disc polishing on the basis of polishing a germanium window by a classical optical processing method, improves the off-disc polishing process, effectively improves the surface finish and polishing efficiency of the germanium window with a medium and small caliber, does not generate great influence on the surface shape of a part, and is beneficial to ensuring the product quality.
Description
Technical Field
The invention belongs to the technical field of germanium window processing, and particularly relates to a high-finish polishing method for a medium and small-caliber germanium window.
Background
With the development of military infrared technology, the infrared optical system is more and more widely applied to airborne, shipborne and tank infrared imaging systems, and the application of the optical material germanium crystal which is indispensable in the infrared system is increasingly increased. It is the most commonly used window and lens material in the 8-12 μm wavelength band. In this band, its chromatic aberration is small, refractive index is high, and the transmissivity can reach more than 97% after plating antireflection film on both sides. The optical processing process of the crystal material is approximately the same as the optical glass processing process, and the processing of the specific germanium crystal material can be finished by the polishing of the conventional classical single-axis machine, the polishing of the annular polishing machine and the polishing of the double-sided polishing machine. Because the hardness of the germanium crystal material is low, the surface finish degree in processing is not easy to control, frequent reworking is easy to occur, and the processing efficiency is low. When the requirement on the surface finish degree is higher, the processing period of the material is longer.
When a germanium window with a medium or small caliber and an outer diameter of 50-150 mm is polished by a classical optical processing method, the surface shape and the surface smoothness of a part are generally detected in the upper disc state, and the part is subjected to lower disc cleaning after the part is qualified. And then, manually repairing the part to remove the residual fine paths on the surface of the part so that the surface smoothness of the part meets the application requirements, wherein in the manual repairing process, a worker generally holds the part by hand and directly polishes the part on polishing flannelette. The process mainly has two problems that the polishing efficiency is low, and the index of local irregularity in the surface shape of the part is easy to change.
Therefore, it is highly desirable to provide a polishing method with high polishing efficiency and capable of achieving high smoothness of medium and small-diameter germanium windows.
Disclosure of Invention
The invention aims to overcome the defects and provides a high-finish polishing method for a medium-small-caliber germanium window.
The technical scheme provided by the invention is as follows:
a high-finish polishing method for a medium-small caliber germanium window, wherein the outer diameter of the medium-small caliber germanium window is between 50mm and 150mm, comprises the following steps:
step one, fine grinding: on a fine grinding polisher, fine grinding is carried out on the part for 20min by carborundum with W14 granularity, the rise difference of the part is controlled within-1 mu m, the surface roughness is Ra1.6 mu m, hemp points with the diameter of 0.7-1 mm do not exist on the surface shape of the part, and large scratches with the length of 15-20 mm and the width of 0.07-0.1 mm do not exist;
step two, rough polishing: on a fine grinding polisher, roughly polishing the part by using alumina polishing solution with W1 granularity, controlling the surface shape of the part in 5 apertures, wherein the surface roughness is Ra0.012 mu m, and the surface shape of the part does not have hemp points with the diameter of 0.7-1 mm, or large scratches with the length of 15-20 mm and the width of 0.07-0.1 mm;
step three, fine polishing: on a fine grinding polisher, continuously carrying out fine polishing on the part by using an alumina polishing solution with W0.3 granularity, controlling the surface shape of the part within 5 apertures, wherein the surface roughness is Ra0.012 mu m, and the surface shape of the part does not have large sand holes with the diameter of 0.7-1 mm, or large scratches with the length of 15-20 mm and the width of 0.07-0.1 mm; the number of scratches within 0.07mm of width is not more than 10;
step four, repairing and polishing on the disc: on a fine grinding polisher, polishing flannelette is matched with diamond solution with W0.25 granularity to respectively polish the parts on a disc, the surface shape of the part is controlled within 5 apertures, the surface roughness is Ra0.012 microns, and the surface smoothness is within V level; the surface shape of the part has no large sand hole with the diameter of 0.7 mm-1 mm, and also has no large scratch with the length of 15 mm-20 mm and the width of 0.07 mm-0.1 mm;
fifthly, repairing and polishing under a plate: the method comprises the steps of cleaning a part on a lower disc, placing the cleaned part in a clamping tool, and performing disc dressing and polishing on the part on a fine grinding polisher by using polishing flannelette and a diamond solution with W0.25 granularity, wherein the surface shape of the part is controlled within 5 apertures, the surface roughness is Ra0.012 mu m, the surface finish is within V grade, large sand holes with the diameter of 0.7-1 mm do not exist on the surface shape of the part, and large scratches with the length of 15-20 mm and the width of 0.07-0.1 mm do not exist on the surface shape of the part.
Preferably, in the step one, the rotating speed of a main shaft of the fine grinding polishing machine is 70 r/min-60 r/min; the rotating speed of the pendulum shaft is 60 r/min-50 r/min, and the load is 50N-70N.
Preferably, in the second step, the third step, the fourth step and the fifth step, the rotating speed of a main shaft of the fine grinding polishing machine is 40 r/min-50 r/min; the rotating speed of the pendulum shaft is 30 r/min-40 r/min, and the load is 50N.
Preferably, in the fourth step, the base material of the polishing mold on the fine grinding polisher is aluminum, a cypress oil layer with the thickness of 3 mm-5 mm is coated on the polishing surface of the polishing mold, then a polishing flannelette layer with the thickness of 1 mm-2 mm is adhered on the surface of the polishing mold, so as to prepare the polishing mold, when in use, the polishing mold is washed clean, the diamond solution is uniformly sprayed on the surface of the polishing flannelette layer, and then the part to be processed is placed on the polishing mold for polishing on a disc.
Preferably, in the fifth step, the base material of the clamping tool is polytetrafluoroethylene, the upper part of the clamping tool is a clamping part, the lower part of the clamping tool is a handle part, a corresponding groove body is machined at the top end of the clamping part according to the outer diameter and the thickness of the part, a layer of polishing flannelette is adhered to the surface of the groove body, when the polishing tool is used, the surface of the part to be machined faces downwards, the non-machining face faces upwards, the part is pressed on the polishing die, and then the polishing tool is operated to perform polishing under a disc.
Preferably, the time of rough polishing is more than 8h, the time of finish polishing is more than 4h, the single polishing time of on-disc polishing is 15 min-20 min, and the single polishing time of off-disc polishing is 3 min-5 min.
Preferably, the finish grinding polisher adopts an MMP400B type precision finish grinding polisher.
The invention also includes other components or steps which are conventional in the art, and further, non-limiting steps, devices or components of the invention are known in the art.
The working principle of the invention is that firstly, in the fine grinding step, after single grinding for 20min, the surface quality and the surface shape of the part can be effectively improved, and the difficulty of the polishing stage is reduced. On the basis, a sample is polished, the polishing stage is carried out in three stages according to the type and the granularity of polishing powder, the main purpose of rough polishing is to quickly correct the surface shape of a part, the rotating speed of a main shaft and the rotating speed of a swing shaft of equipment can be properly adjusted according to the surface shape change of the part in the polishing stage, and the surface shape of the part can be basically controlled to be about 5 times of a low aperture after the polishing of the stage is generally 8 hours. Meanwhile, the surface of the part is polished to be very bright, the finish degree is obviously improved compared with that of the part after fine grinding, but a large number of fine paths exist on the surface, and the finish degree grade of the surface of the part is limited. The polishing powder with finer granularity is needed for correction. During fine polishing, W0.3 aluminum oxide polishing powder with smaller particle size is selected to continuously polish the part, equipment parameters are kept unchanged, fine lines on the surface of the part are effectively removed after polishing for about 4 hours, and the surface smoothness is further improved. But the surface still has a few fine paths away from the surface finish to which the part is applied, which analysis has found to be relevant to polishing the substrate. Because the hardness of germanium crystal material is lower, the polishing mould used for polishing has a hardness of 60 degrees (Shore A), but the hardness is still higher, and scratches are easily caused on the surface during actual polishing. Therefore, adjustment needs to be made for a polishing substrate, the polishing flannelette substrate manufactured by the method is applied to polishing, the hardness of the substrate is obviously reduced relative to that of an asphalt mould, and a diamond solution with hardness higher than that of alumina and slightly lower grain size is selected as a polishing solution so as to ensure the efficiency of a part during polishing. By applying the on-disc repairing and polishing method, the repairing and polishing is carried out for about 15-20 min once, the equipment parameters are unchanged, and the fine paths on the surface of the repaired and polished part are basically removed completely, so that the requirement on the surface finish of the part can be better met. Because the polishing time is short, the surface shape of the part is not obviously changed, and the requirements of drawings can be still met. During cleaning of the lower disc, a small amount of shallow fine paths can appear on parts; before vacuum coating, a small amount of printing ink appears on the surface. This is disadvantageous for vacuum coating and may affect the firmness of the film. The part needs to be refurbished again to improve surface quality. By designing the special clamping tool, the parts can be directly repaired and polished under the plate without re-feeding the parts, and shallower fine paths and imprints existing on the surfaces of the parts are effectively removed, so that the smoothness of the surfaces of the parts is ensured.
Compared with the prior art, the invention has the following beneficial effects: the invention provides a polishing process combining on-disc polishing and off-disc polishing on the basis of polishing a germanium window by a classical optical processing method, improves the off-disc polishing process, effectively improves the surface finish and polishing efficiency of the germanium window with a medium and small caliber, does not generate great influence on the surface shape of a part, and is beneficial to ensuring the product quality.
Drawings
FIG. 1 is a process flow diagram of the present invention in an example.
Fig. 2 is a schematic structural diagram of a trimming and polishing die according to the embodiment of the invention.
Fig. 3 is a schematic structural diagram of the clamping tool in the embodiment of the invention.
Fig. 4 is a schematic top view of the clamping tool shown in fig. 3.
Fig. 5 is a schematic structural diagram of a first component in embodiment 1.
Fig. 6 is a schematic structural view of a second component in embodiment 2.
Fig. 7 is a side view of the structure of fig. 6.
A specific embodiment;
the present technology is described in further detail below with reference to the attached drawings and the detailed description.
Example 1:
as shown in FIG. 1, the invention provides a medium and small caliber germanium window high finish polishing method, which is used for polishing a germanium window shown as a part I in FIG. 5, and has the following technical indexes: n =5,. DELTA.N =1,B = V,. Theta =1', effective Φ 100mm (where N denotes the number of apertures on the part surface shape,. DELTA.N denotes the amount of adjustment of the apertures on the part surface shape,. Theta denotes parallelism, B is the surface finish, and effective Φ 100mm denotes that the effective Φ 100mm is effective within a 100mm diameter of the center point of the part surface shape), comprising the steps of:
step one, fine grinding: on a fine grinding polisher, fine grinding is carried out on the part for 20min by carborundum with W14 granularity, and the rotating speed of a main shaft of the fine grinding polisher is 70 r/min-60 r/min; the rotating speed of the pendulum shaft is 60 r/min-50 r/min, the load is 50N-70N, the surface quality and the surface shape of the part can be effectively improved, and the difficulty in the polishing stage is reduced.
Step two, rough polishing: on a fine grinding polishing machine, roughly polishing the part by using alumina polishing solution with W1 granularity, wherein the rotating speed of a main shaft of the fine grinding polishing machine is 40 r/min-50 r/min; the rotating speed of the pendulum shaft is 30 r/min-40 r/min, and the load is 50N; after rough polishing for 8h, the surface shape of the surface of the part can be basically controlled to be about 5 times of low aperture. Meanwhile, the surface of the part is very bright, the smoothness is obviously improved compared with that of the part after fine grinding, but a large number of fine paths exist on the surface, and polishing powder with finer granularity is required to be used for correction.
Step three, fine polishing: on a fine grinding polisher, continuously performing fine polishing on the part by using alumina polishing solution with the granularity of W0.3, wherein the rotating speed of a main shaft of the fine grinding polisher is 40-50 r/min; the rotating speed of the pendulum shaft is 30 r/min-40 r/min, the load is 50N, and after the fine polishing is carried out for 4 hours, the fine lines on the surface of the part are effectively removed, and the surface finish is further improved. But the surface still has a few fine paths and has a certain distance with the surface smoothness required by the application.
Step four, repairing and polishing on the disc: on a fine grinding polisher, polishing flannelette is matched with diamond solution with W0.25 granularity to respectively carry out on-disc dressing and polishing on parts, the single dressing and polishing time is 15-20 min, and the rotating speed of a main shaft of the fine grinding polisher is 40-50 r/min; the rotating speed of the pendulum shaft is 30 r/min-40 r/min, the load is 50N, and after the disc is repaired and polished, the fine paths on the surface of the part are basically removed, so that the requirement of the part on the surface smoothness can be better met. Meanwhile, the polishing time is short, so that the surface shape of the part is not obviously changed, and the application requirement can be still met.
Fifthly, repairing and polishing under a plate: after cleaning the lower disc, the part is placed in a clamping tool aiming at the shallow fine paths on the surface, and on a fine grinding polisher, polishing down disc polishing is respectively carried out on the part by using polishing flannelette and W0.25-granularity diamond solution, the single polishing time is 3-5 min, and the rotating speed of a main shaft of the fine grinding polisher is 40-50 r/min; the rotating speed of the pendulum shaft is 30 r/min-40 r/min, the load is 50N, and the special clamping tool is applied, so that the parts can be directly repaired and polished without re-hanging the parts on the disk, the fine paths generated in the process of cleaning the lower disk are effectively removed, and the surface smoothness of the parts is ensured.
Specifically, as shown in fig. 2, the base material of the polishing mold on the fine grinding polisher in the fourth step is aluminum, a cypress oil layer 1 with a thickness of 3 mm-5 mm is coated on the polishing surface of the polishing mold, then a polishing flannelette layer 2 with a thickness of 1 mm-2 mm is adhered on the surface of the polishing mold, so as to prepare the polishing mold, when in use, the polishing mold is cleaned, the diamond solution is uniformly sprayed on the surface of the polishing flannelette layer, and then the part to be processed is placed on the polishing mold for polishing on a disc.
Further, as shown in fig. 3 and 4, the base material of the clamping tool is polytetrafluoroethylene, the upper portion of the clamping tool is a clamping portion 3, the lower portion of the clamping tool is a handle portion 4, a corresponding groove body 5 is machined at the top end of the clamping portion according to the outer diameter and the thickness of the first part, a layer of polishing flannelette 6 is adhered to the surface of the groove body, when the polishing tool is used, the surface of the first part to be machined faces downwards, the non-machining surface faces upwards, the first part is pressed on the polishing die, and then the polishing machine is operated to perform polishing under a disc.
Through detection, the product meets the requirements of polishing technical indexes.
Example 2:
as shown in fig. 6 and 7, the present embodiment is different from embodiment 1 only in that the present embodiment is used for machining a second part, and the polishing specifications are as follows: n =5, Δ N =1,B = vii, θ =2'. The detection proves that the product also meets the requirements of the polishing technical indexes, and the feasibility of the polishing method provided by the application is verified again.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (7)
1. A high-finish polishing method for a medium-small caliber germanium window, wherein the outer diameter of the medium-small caliber germanium window is between 50mm and 150mm, and is characterized in that: the method comprises the following steps:
step one, fine grinding: on a fine grinding polisher, fine grinding is carried out on the part for 20min by carborundum with W14 granularity, the rise difference of the part is controlled within-1 mu m, the surface roughness is Ra1.6 mu m, hemp points with the diameter of 0.7-1 mm do not exist on the surface shape of the part, and large scratches with the length of 15-20 mm and the width of 0.07-0.1 mm do not exist;
step two, rough polishing: on a fine grinding polisher, roughly polishing the part by using alumina polishing solution with W1 granularity, controlling the surface shape of the part in 5 apertures, wherein the surface roughness is Ra0.012 mu m, and the surface shape of the part does not have hemp points with the diameter of 0.7-1 mm, or large scratches with the length of 15-20 mm and the width of 0.07-0.1 mm;
step three, fine polishing: on a fine grinding polisher, continuously carrying out fine polishing on the part by using an alumina polishing solution with W0.3 granularity, controlling the surface shape of the part within 5 apertures, wherein the surface roughness is Ra0.012 mu m, and the surface shape of the part does not have large sand holes with the diameter of 0.7-1 mm, or large scratches with the length of 15-20 mm and the width of 0.07-0.1 mm; the number of scratches within 0.07mm of width is not more than 10;
step four, repairing and polishing on the disc: on a fine grinding polisher, polishing flannelette is matched with diamond solution with W0.25 granularity to respectively polish the parts on a disc, the surface shape of the part is controlled within 5 apertures, the surface roughness is Ra0.012 microns, and the surface smoothness is within V level; the surface shape of the part has no large sand hole with the diameter of 0.7 mm-1 mm, and also has no large scratch with the length of 15 mm-20 mm and the width of 0.07 mm-0.1 mm;
fifthly, repairing and polishing under a plate: the method comprises the steps of cleaning a part on a lower disc, placing the cleaned part in a clamping tool, and performing disc dressing and polishing on the part on a fine grinding polisher by using polishing flannelette and a diamond solution with W0.25 granularity, wherein the surface shape of the part is controlled within 5 apertures, the surface roughness is Ra0.012 mu m, the surface finish is within V grade, large sand holes with the diameter of 0.7-1 mm do not exist on the surface shape of the part, and large scratches with the length of 15-20 mm and the width of 0.07-0.1 mm do not exist on the surface shape of the part.
2. The method for polishing the medium and small-caliber germanium window with high finish according to claim 1, wherein the method comprises the following steps: in the first step, the rotating speed of a main shaft of the fine grinding polisher is 70 r/min-60 r/min; the rotating speed of the pendulum shaft is 60r/min to 50r/min, and the load is 50N to 70N.
3. The method for polishing the medium and small-caliber germanium window with high finish according to claim 2, wherein the method comprises the following steps: in the second step, the third step, the fourth step and the fifth step, the rotating speed of a main shaft of the fine grinding polisher is 40 r/min-50 r/min; the rotating speed of the pendulum shaft is 30 r/min-40 r/min, and the load is 50N.
4. The method for polishing the medium and small-caliber germanium window with high finish according to claim 1, characterized in that: in the fourth step, the base material of the polishing mould on the fine grinding polisher is aluminum, a cypress oil layer with the thickness of 3-5 mm is coated on the polishing surface of the polishing mould, then a polishing flannelette layer with the thickness of 1-2 mm is adhered on the surface of the base material, so that the polishing mould is manufactured, when the polishing mould is used, the polishing mould is cleaned, the diamond solution is uniformly sprayed on the surface of the polishing flannelette layer, and then the part to be processed is placed on the polishing mould for polishing on a disc.
5. The method for polishing the medium and small-caliber germanium window with high finish according to claim 4, wherein the method comprises the following steps: and fifthly, the substrate material of the clamping tool is polytetrafluoroethylene, the upper part of the clamping tool is a clamping part, the lower part of the clamping tool is a handle part, the top end of the clamping part is provided with a corresponding groove body according to the outer diameter and the thickness of the part, a layer of polishing flannelette is adhered to the surface of the groove body, when the polishing tool is used, the surface of the part to be processed is downward, the non-processing surface of the part is upward, the part is pressed on a polishing die, and then a fine grinding polishing machine is operated to perform polishing under a disc.
6. The method for polishing the medium and small-caliber germanium window with high finish according to any one of claims 1 to 5, wherein: the rough polishing time is more than 8h, the fine polishing time is more than 4h, the single polishing time of the on-disc polishing is 15-20 min, and the single polishing time of the off-disc polishing is 3-5 min.
7. The method for polishing the medium and small-caliber germanium window with high finish according to claim 6, characterized in that: the fine grinding polishing machine adopts an MMP400B type fine grinding polishing machine.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211339503.2A CN115673881A (en) | 2022-10-26 | 2022-10-26 | High-finish polishing method for medium and small-caliber germanium windows |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211339503.2A CN115673881A (en) | 2022-10-26 | 2022-10-26 | High-finish polishing method for medium and small-caliber germanium windows |
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| CN115673881A true CN115673881A (en) | 2023-02-03 |
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| CN202211339503.2A Pending CN115673881A (en) | 2022-10-26 | 2022-10-26 | High-finish polishing method for medium and small-caliber germanium windows |
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