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Fine grinding (/ fine milling) of plane optical parts (prisms)

1、Fine grinding / fine milling: the fine grinding of plane processing has three purposes:

lForm a better surface shape, and the ideal fine grinding surface shape should be consistent with the surface shape achieved after the parts are polished;

lForm a surface roughness conducive to polishing, so that the polishing time is minimized;

lEnsure the dimensional requirements and parallel difference (tower difference) and other requirements of the machined parts.

lIn the past few decades, the vast majority of plane fine grinding and polishing are still carried out on traditional machine tools, appropriately increasing speed and pressure processing. The fine grinding machine tool is basically the same as the polishing machine tool. The traditional two axis machine, three axis machine, four axis machine and six axis machine are used most.

The shape of the domestic six axis machine is shown in Figure 12-22, and the motion relationship of each axis is shown in Figure 12-23. In the figure, the cantilever 5 driven by the crank connecting rod slider mechanism 4 swings back and forth around the rotating shaft 6, and the part 2 of the hanging plate is driven by the iron pen 1 fixed on the cantilever, which swings with the cantilever and rotates with the rotation of the fine grinding plate 3.

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The swing stroke can be adjusted by the eccentricity of the crank, and the eccentricity of the workpiece disc relative to the fine grinding disc can be adjusted by the expansion and contraction of the iron pen on the cantilever. According to the needs of the processed parts, the workpiece disc can be selected on the fine grinding disc, or the fine grinding disc can be selected on the workpiece disc. On the iron pen, several steel counterweights can be pressed in series according to the process needs to increase the pressure in the grinding process and improve the grinding efficiency. The rotation speed of the spindle of this kind of fine grinding machine is generally not more than 120r/min, so the fine grinding of this machine tool is mainly the fine grinding of steel sand granular abrasive:

The first paragraph generally adopts W20 or Japan’s 800 # ~ 1200#

W10 is generally used for the second segment.

In paragraph 3, W7 can be used according to the needs of some individual products.

2、Now, the precision grinding disc made of diamond pellets is processed. (at present, spherical mirrors are still widely used.)

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The equipment for fine grinding disc processing made of pills has been upgraded compared with that before. It is basically the same as the polishing equipment we often use now. Diamond dish fine grinding can also be processed in several stages.

Initial stage: according to the needs of the product, if the product has high and low, it needs to be roughened with coarse and fine steel sand.

Paragraph 1: generally, 1000 # ~ 1200 #, such as 49b

Paragraph 2: generally 1500 # ~ 2000 #, such as 27c

The following simple matching pictures are for reference

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3、Now upgraded CNC milling machine for finish milling

At present, this method is a method that Xiaobian believes is very efficient for the processing of prism plane disk. It has three main advantages: good appearance, high efficiency and dimensional accuracy control. Of course, this kind of CNC milling machine finish milling processing is also carried out according to the needs of the product. For example, one is for rough and fine milling, and the other is for fine milling. Of course, Xiaobian believes that if small enterprises can cooperate with diamond pellet precision grinding disc as needed. The CNC milling machine carries out the first stage, and the diamond pellet precision grinding disc carries out the second stage. In addition, diamond pellet precision grinding disc can also be replaced by grinding pad in the market at present. Here are some pictures of CNC equipment for you.

   Domestic production and commonly used equipment reference

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Reference of a kind of equipment imported from Japan

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4、Process connection between fine grinding and polishing

In addition to selecting a reasonable technical scheme and designing advanced tooling fixtures, the most important link in the efficient processing of high-precision prisms is to realize rapid polishing. The requirements of the surface shape, angle and surface roughness of prisms are finally realized in the polishing process. Therefore, the connection between fine grinding and polishing is also crucial. There are two requirements for mirror disk shape after fine grinding

One is the requirement of surface shape. Method 1: check with flat crystal sample, and the aperture is n= 0.3~1;

Method 2 use a dial indicator to measure 5 points, and the middle part of the mirror disk is 0.0010~0.0005mm lower than the edge. The specific specifications need to be set according to the caliber and product needs

The second is the requirement of the parallelism of the mirror disk. Measure the parallelism of the whole disk with 4 points and control it within 0.001~0.010mm. The specific specifications need to be set according to the caliber and product needs


Post time: Aug-01-2022