Spelling-block thermoset injection molding bakelite handle

Bakelite handle complex shape because the children what their mold machining cutting method using molding difficulties , the traditional method is the use of cold extrusion process . However, cold extrusion process requires a good plastic deformation of steel in order to get the desired quality of the cavity , so had a lower carbon content of 20 steel. Carburizing hardened with heat treatment method , due to the carburized layer thickness of only 1 mm , lower internal hardness , poor wear resistance and therefore , easy to make plastic parts produced collapse angle , dents and other defects, leaving the lower die life. In recent years, along with the application of pulsed electrical erosion process , although able to replace part of the cold extrusion process is insufficient, however, finish and polishing process of electrical pulses of electrical erosion process is still not satisfied bakelite surface finish requirements , had to use fitter means the process by hand polishing . DZ 1 2 Molded switch handle ( toggle ) shape due to the arcs and straight edges connected to both difficult hand-polished appearance and do not have good quality .
        In the mold base using hardened to HRC 56 an 58 separate pieces type movable mold plate and the fixed mold plate , it has a compact structure , high strength, rigidity, durable without deformation advantages. Mold assembly without the traditional cylindrical pin position, but on four rectangular plug iron positioning, because the iron rectangular plug positioned large contact area , thus positioning stable and reliable. Bakelite handles can withstand dozens of disassembly and accuracy is not affected, and easy disassembly , easy maintenance.
        With bakelite handle wearing parts can be replaced at any time . Mold using the total life of up to 200 million times . Bakelite bakelite handle parts made ​​clear outline , bakelite handle the appearance of good quality . Now spelling -block DZ 12 Molded switch handle ( toggle ) the mold structure , tile combinations and specific manufacturing process methods described below, for mold design and manufacture of peer reference . Two pieces designed as a separate cavity cavity group , bakelite handle the whole mold is put together by the Vice six independent group formed cavity . The cavity is divided into six groups and the two parts, each group of three separate cavity and a screw shaft with a hardened plate HRC56 ~ 58 is connected as a whole. Such dynamic synthesis of two identical mold cavity overall , given the model also makes up two identical chambers as a whole. The dynamic model of the chamber were then fitted within the overall dynamic mold base, with four rectangular plug iron clamp and screw connections. Also here given model cavity method .
        First, bakelite handle pieces moving mold cavity mold cavity combination of moving pieces is composed of nine blocks , two blocks around the bakelite handle exactly the same shape , but it is symmetrical , the other four inserts shaped exactly the same. This simplifies the four merged to become integral pieces of different shapes moving mold cavity . Pressing iron with four rectangular plug and screw connections . Also here given model cavity method .
        First, bakelite handle dynamic model combination chamber pieces moving mold cavity is composed of nine pieces , exactly the same before and after the two shapes , but it is symmetrical , the other four inserts shaped exactly the same. This simplifies the four merged to become integral pieces of different shapes moving mold cavity .
        Second, bakelite handle set pieces combination mold cavity mold cavity is given by the four pieces composed around the shape is the same. After this simplification merged into three different shapes of blocks of a given model to fight cavities .
        Third, the material selection and manufacturing processes bakelite handle molded pieces are pieces of high precision molding mold part of the heart , so in principle the choice of material are: for high wear resistance, long life, small deformation of the steel. For this choice of C r 12 M o V 18 wear-resistant high alloy steel . In preparing the molding pieces manufacturing process, we simplified by merging pieces shaped into seven different shapes, and then press the tile thickness preparation manufacturing technology program. For example: the total number 23 A merger with the number 2 3 B 12 , bakelite handle each thickness 4.3 x12.6 mm margin around each piece put cutting 0.3 mm . Ingredients thickness of 56 mm . Bakelite handle and process procedures required by the drawing wire crossed drilled holes and threaded holes. Then heat-treated hardened to HRC 56 an 58 , after two planes polished , cut the line of control into the seed program , the whole piece by the fitter the cavity surface polishing , and then cut a piece of wire cutting , grinding to the drawing size requirements, Since the whole film processing , fully consistent pieces geometry. All the pieces are here bakelite handle processing technology program , so pieces of high precision , good interchangeability , this is because there is a good means to ensure the sake of technology . Higher accuracy can be achieved when the mold assembly .
        Fourth, the overall dynamic bakelite handle , fixed die holder movable against the overall process , the stationary die holder , nowhere is actually processed hole ( 5 ) in the whole plate, and the shape of the holes are generally rectangular pits. Design requirements bottom side of the vertical plane , the rectangular blind hole machining is a certain degree of difficulty, we use processing technology programs are: Figure crossed by the fitter after drilling the four corners of the use of the platen clamping car lathe machining holes on the faceplate the depth to the drawings , the side discharge margin 0.5 mm , and then on the left two roughing milling finishing allowance of 0.1 to 0.2 mm , and later finishing milling ( or coordinates hit the bed ) , requested the bottom surface of the machined surface is flush with the car , side and bottom vertical .
        Fifth, bakelite handle dynamic model between the base column design appropriate place mat thermosetting plastics injection pressure is much greater than the thermoplastic injection pressure and more generally thermoplastic injection pressure of 40 ~ 130kg / c also, and for thermosetting plastics injection pressure : 1200 ~ 2400kg/em. To this end we have found in the past thermosetting plastic injection mold , often in the course , bakelite handle in the middle part of the flash appears thickened . ( Especially in multi-cavity molds ) .
When the new mold sample is ideal ; arising from the use of plastic parts flying side gradually thickened , sometimes as much as more than 0.5 mm , while the movable die plate design thickened enough rigidity and hardened by heat treatment , is still found in the middle elastic deformation portion . Between the movable mold and place mats to increase the base column design , bakelite handle makes moving mold plate stiffness is greatly enhanced , to overcome the elastic deformation , the use of more than four years has been tested and found no deformation. Thus it is possible that the thermosetting plastic parts is always maintained between the burr 0.05 to 0.08 mm.
        Sixth, the design and improvement of exhaust ducts thermosetting plastic injection mold exhaust ducts rational design of plastic parts is the inherent quality and appearance quality assurance. Bakelite handle long to take 0.2 to 0.3 mm think is ideal, thus making the thermoset plastic parts flying left side of 0.3 mm thickness , affect the appearance of quality , and to organize trouble. We refer to the data while abroad , the study found that mobility thermosetting plastics : thermosets mobility than the mobility of hot plastic is much better , there are 0.05 mm gap must escape the material , the occurrence of burrs . So as long as the position of the gas tank design reasonable , select 6 X O.06 mm ( W x D ) , has enough gas emissions without affecting the quality of molding . Meanwhile thermoset plastic parts flying in formation 0.06 mm edge off on their own in the molding process , without finishing , good appearance quality bakelite handle plastic parts .
        Seven anti- putt reset mechanism design and improvement of the mold using anti- putt reset seat installed in the fixed mold hardened by heat treatment of HRC auxiliary pusher 56 a 60.
        Improve the accuracy of the reset , thermoset plastic parts ensure smooth mandrel surface . Since the auxiliary anti- putt putt small diameter than the outer diameter of 2 mm , so installation is easy , bakelite handle fixed mold seat pitch less precision machining , drilling by the fitter to meet the requirements .
        Eight high-density small diameter tube direct electric heating of the mold cavity ( internal heating ) using high-density thin small diameter 12 mm heating pipes direct heating of the mold cavity . With the gap bakelite handle mold and electric tube aperture of 0.1 to 0.2 mm . ( Used in the past in 20 mm heating pipes , heating pipes and mold aperture with the gap as :.. L 5 mm to 1 mm with the gap narrowing due to reduce the heat loss , so bakelite handle mold temperature , high energy efficiency , low power consumption little more substantial savings can mold heating energy consumption. ( and because of the gap narrowing the glow tube surface easily oxidized, and improve the life of heating pipes ) .