| Traditional β light source,also known as β lamp,is an excellent light source for illumination in a small field of view in a dark environment due to its unique advantages such as stable light intensity,long luminous time and no external power supply.Glass tube type β lamp is currently the most widely used β light source,its production process usually uses flame hot melt sealing to achieve the sealing of glass tube,but flame hot melt sealing has many shortcomings,for example,there are problems such as flat heads and difficult to control the flame temperature,limiting the development of β light source industrialization.The rise and development of laser technology provides a new solution for the preparation of glass tube β light source.In this paper,the laser technology is applied to the preparation of βlight source glass tubes.With the goal of sealing in a short time,the technical research of laser hot-melt sealing of glass tubes is carried out,and the influence of the main process parameters in different sealing processes on the sealing effect is analyzed.The main research work and conclusions of this paper are as follows:1.The research status of β light source and laser welding glass at home and abroad is reviewed.By comparing and analyzing three kinds of laser welding glass technology,the research of laser hot melt sealing technology of glass tube is carried out with middle and far infrared laser heat conduction welding glass as reference.2.Research on the technology of end face hot-melt sealing glass tube.The glass tube with outer diameter of 9 mm,wall thickness of 2 mm and length of 100 mm is still selected,and the laser is irradiated in the middle of the glass tube.When the glass tube reaches the melting state under the laser irradiation,the wire drawing and sealing is completed under the clamping and translation of the motor.By comparing the sealing morphology and sealing time under different process parameters,it is concluded that the sealing morphology is better when the laser power is increased and the sealing time is shortened while the residual gap is eliminated,but the excessive laser power will produce a large number of bubbles in the melting area of the glass tube,which will seriously affect the luminous effect;As the rotational speed increases,the time to achieve glass tube sealing decreases,and the number and volume of bubbles within the melting zone decreases,but when the rotation speed increases by 300 r/min,the bubbles in the melting zone and the sealing time do not change;The diameter of the target spot determines the melting volume of the glass tube under laser irradiation,so the sealing time cannot be judged by a single power density.For a given size of the glass tube,it is necessary to select the appropriate diameter of the target spot.The optimal process parameters for sealing glass tubes of this size under this process technology are: laser power of 120 W,target spot diameter of 4 mm,rotation speed of 300 r/min.Finally,the infrared thermometer is used to measure the temperature field of the glass tube during the end face hot melt sealing,and the distribution of the temperature field in time and space is obtained,and the safety range of the filler inside the glass tube under this process is preliminarily obtained.3.Research on the technology of hot-melt wire drawing to seal glass tubes.The glass tube with outer diameter of 9 mm,wall thickness of 2 mm and length of 100 mm is still selected,and the laser is irradiated in the middle of the glass tube.When the glass tube reaches the melting state under the laser irradiation,the wire drawing and sealing is completed under the clamping and translation of the motor.By comparing the time and sealing effect of wire drawing and sealing,it is concluded that the time of wire drawing and sealing is shortened with the increase of laser power,When the laser power increases,a large number of bubbles are generated inside the melting zone;The small diameter of the light spot on the target surface leads to the small volume of the melting zone.There is not enough melting volume to seal the glass tube during the twisting wire drawing process.The optimal process parameters for sealing glass tubes of this size under this process technology are: laser power of 140 W and target spot diameter of 3 mm.Finally,by comparing the sealing time of the end face hot-melt sealing,it is concluded that the hot-melt drawing process can effectively shorten the sealing time.4.Research on the technology of hot-melt cutting and sealing glass tubes.Select the capillary glass tube with an outer diameter of 1.5 mm,wall thickness of 0.2 mm and length of 100 mm,irradiate the laser in the middle of the glass tube,and use the high power density laser beam to complete the sealing while cutting.By comparing the sealing morphology and sealing time under different process parameters,it is concluded that the laser power mainly affects the time of cutting and sealing,and the time of cutting and sealing is shortened with the increase of power;the diameter of the light spot on the target surface determines the shape of the sealing area.If the light spot is too large,the end of the sealing area will be large,and if the light spot is too small,the volume of the melting area will be small enough to achieve the sealing;With the same processing parameters,the better sealing morphology can be obtained by using the post-coke processing position.The optimal process parameters for sealing glass tubes of this size under this process technology are: laser power is 140 W,target spot diameter is 3 mm,and the post-focal processing position is adopted.This paper finally realizes the sealing of glass tubes of different sizes through three sealing technologies,and the sealing morphology is intact,which lays a good foundation for the subsequent research and development of β light source,and also provides a new solution and reliable engineering experience for the connection and sealing of brittle materials such as glass. |
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