The invention discloses an automatic 
assembly production line of buzzers, which comprises a feeding mechanism, a glue 
coating mechanism, a 
buzzer piece placing mechanism, a straight contact pin placing mechanism, a first 
thermoplastic pipe placing mechanism, an inclined contact pin placing mechanism, a second 
thermoplastic pipe placing mechanism, a 
thermoplastic pipe heat sealing mechanism, a contact pin 
welding mechanism, a dispensing mechanism, a curing mechanism and a detecting and sorting mechanism, which are sequentially arranged on a work table; the glue 
coating mechanism comprises an automatic shell locating mechanism located behind a glue applicator, and the automatic shell locating mechanism comprises a motor, a rotating jig, an 
optical fiber sensor, a motor base, a supporting plate and a sensor bracket; the 
optical fiber sensor is a reflective 
optical fiber sensor and is arranged to be aligned to the shell; and the optical 
fiber sensor is installed on the upper part of the sensor bracket, and the lower part of the optical 
fiber sensor is fixed to the side plate of the supporting plate. The automatic 
assembly production line disclosed by the invention has the advantages of smart design and simple structure, realizes high level 
automation, replaces the manual operation, reduces the cost of manpower and physical resources and improves the production efficiency of the 
assembly line.