How to stabilize the aperture during optical lens processing

来源:juka optics 发布时间:2020-04-01 00:00:00 浏览量:2975

Mid-to-high-end optical systems have higher and higher requirements for the rms of optical glass lenses. How to make the aperture stable in the process without affecting operation efficiency, increasing costs and ensuring quality has now become a "hot topic" for discussion. As the professional convex and concave lens manufacturer in China for over 15 years, JUKA Optical will help you to find the basic conditions for aperture stability.


Factors Affecting Aperture Instability:


1. Processing conditions of optical lens:

1) The size of the particle diameter of the abrasive powder and the size ratio have an effect on the aperture. Larger particle diameter of the grinding powder and concentration, bigger change to the curvature radius of the grinding dish. If compared with clear water, the aperture will change to a higher direction.


2) The rotating speed affects the local irregularity of the aperture. The linear velocity of the edge of the grinding dish is not the same as the linear velocity of the center. The more the lens swings out of the edge of the mortar, the more the lens aperture changes to a negative aperture. It will cause the center and edge of the lens to be ground unevenly.


3) The amount of pressure has a direct effect on the the lenses with thin center and D / T> 10. The effect of the pressure on the shape is mainly caused by the uneven force on the entire surface of the lens.


4) Machining time also affects the change in surface accuracy. Because the curvature radius of the grinding dish must always be maintained, it is inevitable that the center of the grinding dish will wear quickly.


5) Swing size adjustment: if the swing is too large, the lens aperture will change to a low aperture, accompanied by a low and medium appearance; If the swing is too small, the lens aperture changes to a high aperture, accompanied by the appearance of medium and high.


6) Adjustment of quasi-ball core: The adjustment of the quasi-ball core is good or bad, which will affect whether the pressure is evenly applied.


7) Adjustment of coaxiality: the coaxiality means that the center points of the main shaft, the relay fixture and the grinding plate must be consistent. If the requirements of the center point are not consistent, the lens will jump during operation, and the uneven running will affect the surface accuracy.


8) Adjust the height of the stick: The string rod presses the clamp; the clamp drives the lens to rotate, and the transmission pressure cannot be guaranteed when the string rod is high, and the abrasive skin is easily scratched when the string rod is low.


9) Check that the parts are secure and locked.


10) The offset of the lens on the grinding plate.


11) When the lens swings out too much, the lens is prone to embossing, the surface cost is easy to lower, and it is easy to tilt when swinging to the edge. When the swing is small, the amount of wear is small.


12) Parallelism of the swing arm: The non-parallel swing of the swing arm will affect the centerline of the lens and cannot overlap the centerline of the grinding dish.


2. Processing Equipment of Optical Lens:

1) The beating of the main shaft of the machine shifts the center point of the shaft, causing the lens to run erratically during processing.


2) The gap between the movable joints of the machine is too large, which will cause the forces on the lens to swing in and out, and the lenses will be unevenly stressed.


3) Inflexibility of cylinder expansion and contraction, abnormal sound and vibration of the machine.


4) The stability of the string stick is not strong, and the distance between the string stick and the grinding plate is too large, which will cause the tip of the string stick to tremble during processing to affect the accuracy of the surface shape.


3. Jigs and Tools:

1) Whether the matching of the outer diameter of the tool is accurate, that is, the size ratio of the combined dish and the repairing dish, the size ratio of the repairing dish and the grinding dish, and the size ratio of the grinding dish and the lens.


2) The local error of the drill repair dish is equal to the local error of the lens.


3) The accuracy of the curvature surface of the grinding plate and the fixture is an important factor that determines that the processing surface of the lens, the force receiving surface and the fixture completely match.


4) Design of end hole and height of fixture.


5) The flatness and height of the end face of the relay tools.


6) Grinding shape of string rods: The polishing of string rods is the key to the smooth running of the fixture table. The string rods are too blunt, which affects the smooth operation.


7) Repair of grinding dish: It is difficult to evenly repair the surface of the grinding dish by hand. Because the amount of swing of the grinding dish is controlled by hand, the rotation speed of the grinding dish is not balanced, so it is not recommended to repair by hand.


8) Paste and tightness inspection of the clamp shell: this item can cause the deformation of the lens surface shape the mostly.


9) Flattening of pads and pads: The pads and pads are elastically selected to be pads, the outer diameter and thickness of the pads, and smooth.


10) The effect of the depth of the terminal: the terminal depth; the string rod and the terminal interfere when the terminal swings. The terminal is shallow; the string rod and terminal are easy to fall out during the swing.


11) Adjustment timing when the shape accuracy changes: Adjust when the shape accuracy changes. Do not wait until the surface shape exceeds the specifications. At that time, the shape accuracy will not be easy to control.


12) Frequency of face inspection: The frequency of face inspection is high. It is easy to control because it understands the regularity and trend of surface shape accuracy.




Necessary conditions for aperture stability


1) When the aperture changes to a high aperture, it is difficult to debug at medium and high levels, the edge is large, and the surface accuracy is difficult to process, the concentration ratio should not be too thick. The concentration of the grinding liquid can be controlled not higher than 1.020; the particle diameter of the grinding powder is selected to be smaller. The opposite is true when the aperture changes to a low aperture and it is difficult to debug at a low or medium range.


2) If the rotation speed is too fast, the amount of side sag will be increased. If the coaxiality is too large, the lens will be suspended and the center will be difficult to contact for grinding. The surface of the optical lens is not evenly worn. Lenses with large outer diameters are processed at low speed (<1500 rpm), and lenses with small outer diameters are processed at high speed (> 2500 rpm). When the pressure is large, the local force is large; when the pressure is small, the force on the lens surface is relatively uniform. For the lenses with a thin center and D / T> 1.0 ,the pressure should be light and not heavy. Therefore, if the surface accuracy is stable on parts that are difficult to machine, the processing conditions must be set in consideration of light concentration, light pressure, slow rotation speed, and short time.


3) The ideal size of the fixture must be calculated according to the formula, and the manufacturing error must be controlled. The local error correction of the drilling repair dish is within 0.0005mm.


4) The adjustment of the quasi-ball core is to determine the swing amplitude. The small swing is difficult to distinguish the accuracy of the core.


5) The specific method of adjusting the coaxiality is that the grinding plate is mounted on the relay fixture, and the ball core corrector is used for correction. The runout deviation is within 0.03mm, and the height of the string rod and the grinding plate is preferably adjusted to 0.1mm. The amount of the lens on the grinding plate is about 1/5 of the lens diameter. The polished shape should match the shape of the terminal hole and be conical. Grinding dishes are repaired with a machine. Don't set up more to overcome the low surface. If the surface is low, directly repair the drill and repair the dishes.


6) When the fixture shell is pasted, the glue is prevented from overflowing into the curvature surface of the fixture table.


If you have any optical lens need to customized, please contact professional optical lens manufacturer——JUKA Optical.

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