Hello everyone, today I will introduce to you the measurement methods of micro-hole processing, which are as follows:
For a through hole with a hole depth of less than 1 mm, the roughness of the inner wall of the hole can be roughly observed with the aid of a magnifying glass. In this study, a reflection microscope was used to directly observe the inner surface of the orifice as a control for the measured roughness test. Obviously, this method cannot be used to accurately measure the inner wall roughness of tiny holes with a hole depth of 4 mm. Due to the small aperture of the measured tiny hole, the controllable light source cannot penetrate into the hole accurately, so it cannot be measured by the method of light interference principle. If the direct contact measurement method is adopted, although the diameter of the probe is smaller than the inner diameter of the micro-hole, the subsequent part connected to it is too large, so that the probe cannot penetrate into the micro-hole for direct measurement. Therefore, the author adopts the subdivision method for the tiny holes, and uses a profiler with a taper of 60° to directly measure the inner surface of the micro holes exposed after the division to obtain accurate data.
There are two methods for micro-hole processing: one is to cut the micro-hole after processing, and the other is to drill holes along the joint seam on two smooth flat plates that are closely combined. Due to the small hole diameter, the cutting after processing should be a thin plate cutting. At this time, laser cutting should be used to obtain higher cutting accuracy. However, due to the large diameter of the cutting spot (for example, when the thickness of the thin plate is 5mm and the required cutting speed is 1.5m/min, the diameter of the spot is 0.2mm[6]), which is close to the diameter of the processed tiny holes, and the remaining tiny holes after cutting The inner surface is too small to perform roughness measurement; at the same time, in order to protect the inner wall of the tiny hole from being affected by splashes during cutting, wax and other substances are usually injected into the tiny hole before cutting to protect the inner wall of the hole. The influence of the protective material on the measurement results of the inner wall roughness of the tiny holes cannot be evaluated, so it is necessary to be very careful when using this cutting process to avoid measurement difficulties. In view of the above reasons, the second method of micro-hole processing is adopted in this test: two flat plates are processed, and after they are fastened, a seam hole is made along the contact surface of the two plates, and then the two plates are separated, and the exposed micro holes are directly measured. surface. The roughness of the inner wall of the tiny hole measured by this method can accurately reflect the actual processing condition of the inner surface of the tiny hole.
When drilling, the entire length of the two plates is clamped with flat-nose pliers to avoid bending or uneven force on the plates during laser drilling. The laser drilling device is equipped with a microscopic magnifying device with a magnification of 57 times, which can observe the contact surface of the two flat plates more clearly, so it can better ensure the relative position of the laser beam and the contact surface of the flat plate and ensure that the contact surface is along the contact surface. Punch the seam holes. The verticality of the plate contact surface and the processing table can be ensured by adjustment.
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