The study of the metal cutting deformation process is of great significance for the development and progress of cutting technology, ensuring the quality of processing, reducing production costs, and increasing productivity. Because of the various physical phenomena in metal cutting, such as cutting force, cutting heat, tool wear, and the quality of the processed surface, all are based on the process of chip formation, and many problems in production practice, such as scales, BUE, vibration, chipping and chip breaking are all related to the cutting deformation process. Therefore, it is very important to study the metal cutting deformation process. There are many ways to study the metal cutting deformation process, such as the side grid deformation observation method, high-speed photography method, rapid drop-off method, scanning electron microscopy, etc., but these methods require a long period, lack of immediacy, and change the cutting conditions Difficulties, etc. Using industrial television, put the camera on the microscope head and observe the metal cutting deformation process on the TV screen. When used together with a video recorder, the metal cutting deformation at any cutting speed can be recorded first, and then released through slow speed, fixed frame and other functions, which is more convenient for us to observe and analyze the cutting deformation process. This method is intuitive and has good immediacy. It is a good way to observe the cutting deformation process. The principle of industrial television camera law Industrial television camera law is the use of lens imaging principle, the image projected onto the photoelectric converter, so that the image becomes a signal, and then these electrical signals are converted into video signals, received on the TV, ie The scene shot by the camera can be seen on the TV screen. The camera has a set of lenses with a focal length f. It projects distant scenery onto a circular photoelectric converter in the camera. When the object AB is placed within the focal point and twice the focal length, then at l' (out of the double focal length) an enlarged inverted real image A'B' is formed. Lens image formula 1/l+1/l'=1/f (1) Where: l' is the image distance: l is the object distance: f is the focal length. Calculate l' from formula (1), then place the lens away from the camera photoelectric converter l′, and then place the cutting deformation process away from the lens l, then you can observe the cutting deformation process. According to this method, we can only see the deformation of the side of the workpiece when it is being cut. For ease of observation, we can draw squares on the side of the workpiece, and then print the black and white squares (0.126×0.126) by etching. In this way, the distortion of the metal cutting can be clearly observed through the distortion of these small cells. 2 Industrial television camera device designed television camera device. Its characteristics are simple, easy to operate, and can clearly observe the process of cutting deformation. The camera is fixed on the lateral carriage of the vertical milling machine by screws, and the carriage is moved laterally to adjust the camera to an appropriate position. The workpiece sample is mounted on the longitudinal table of the milling machine through the fixture, and the tool is installed on the spindle of the vertical milling machine. in. In order to prevent the camera from too much vibration, the tool is fixed during operation and the workpiece moves slowly in the longitudinal direction. In the cutting, although the use of right-angle planing, but the chip will still turn out on both sides, thus affecting the camera side of the visual effect. For this purpose, a piece of glass is used to block the chips on the side of the observation, so that the side of the knife is pressed against the glass. This will prevent the chips from flanging and make the observation clearer. 3 Camera lens assembly design Since the lens of the original camera cannot enlarge the small area of ​​the cutting deformation, an additional lens must be selected and the lens assembly must be designed. Determination of lens magnification The length of the diagonal of the industrial television screen is 440mm, and the aspect ratio is 3:2. In order to clearly reflect the metal cutting deformation on the TV screen, the screen width direction (ie, the vertical direction) is evenly divided into six grids, ie, the workpiece area occupies two grids, the cutting area occupies two grids, and the swarf area occupies two grids. The camera photoelectric converter is a circular target with a diameter of Ø14, but the effective image projected onto it must be a rectangle that is geometrically similar to the television screen, ie, the effective pattern aspect ratio of the photoelectric converter is 3:2. From the figure: a=7.77mm, b=11.65mm. In fact, the length of each side of the workpiece sample is 0.126mm, and the total width of the six grids A=6×0.126=0.756mm, so the lens magnification b=a/A=7.77/0.756≈10 (times)
The focal length of the lens is determined according to the lens imaging formula 1/l'+1/l=1/f and the magnification b=l'/l, and f=l'(/1+b) or f=lb/(1+b) is obtained. (2) It can be seen from (2) that when b is fixed, l′ is proportional to f, that is, when f↑, l′↑ will increase the lens assembly structure. In order to make the structure compact and reasonable, f should be chosen smaller. Taking into account the fixture structure, now choose f = 16.5mm. Lens assembly device lens assembly device.
In the device, since the focal distance is small, the object distance l is short, so that it is difficult for the light to effectively reach the cutting zone. For this purpose, a half mirror is used to project the light (slide projector) from the direction of the main optical axis to the cutting zone. According to the formula l'=(1+b)f=182mm, the lens is mounted 182mm away from the photoelectric converter of the camera. Because the lens is far and is a cantilever structure, an elongated cylinder must be made of aluminum and can be adjusted. Jiao. 4 Conclusions After the previous design, an industrial television camera system for observing the metal cutting deformation process can be put into use. According to actual use, the television camera system operates stably, and clear images can be obtained within a working speed range of 14 to 900 mm/min. This system provides an effective means of observation for studying metal cutting deformations, and it has played a very important role in understanding the laws of metal cutting processes and accelerating the development of cutting technology.
The focal length of the lens is determined according to the lens imaging formula 1/l'+1/l=1/f and the magnification b=l'/l, and f=l'(/1+b) or f=lb/(1+b) is obtained. (2) It can be seen from (2) that when b is fixed, l′ is proportional to f, that is, when f↑, l′↑ will increase the lens assembly structure. In order to make the structure compact and reasonable, f should be chosen smaller. Taking into account the fixture structure, now choose f = 16.5mm. Lens assembly device lens assembly device.
In the device, since the focal distance is small, the object distance l is short, so that it is difficult for the light to effectively reach the cutting zone. For this purpose, a half mirror is used to project the light (slide projector) from the direction of the main optical axis to the cutting zone. According to the formula l'=(1+b)f=182mm, the lens is mounted 182mm away from the photoelectric converter of the camera. Because the lens is far and is a cantilever structure, an elongated cylinder must be made of aluminum and can be adjusted. Jiao. 4 Conclusions After the previous design, an industrial television camera system for observing the metal cutting deformation process can be put into use. According to actual use, the television camera system operates stably, and clear images can be obtained within a working speed range of 14 to 900 mm/min. This system provides an effective means of observation for studying metal cutting deformations, and it has played a very important role in understanding the laws of metal cutting processes and accelerating the development of cutting technology.
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