Thermosetting plastic injection mold design handle

 

Abstract According to thermosetting plastics injection molding process principles, combined with the characteristics of the product structure, the use of flaps and activities clamping inserts threaded core structure, designed thermosetting plastic handle injection mold, production-proven, and its structure is simple and practical injection molding process is stable and reliable.

 

Keywords: thermosetting plastics; handle; injection mold; lobe clamping structure

 

$ Foreword

 

For thermosetting plastics processing, the traditional approach is to use compression molding process pressure injection molding process and methods to produce plastic parts products. Both methods process is complicated, labor-intensive, long molding cycle, low productivity, molds easily damaged, unstable quality of the molded product. Thermosetting plastic parts by injection molding, with the former, compared with a simplified operating process, shorten the molding cycle, improve production efficiency, reduce labor intensity, improve product quality, longer tool life and other advantages. Thus, with the continuous development of the plastic molding process, injection molding thermoset plastics technology more widely.

 

Thermosetting plastic injection molding is the principle of molding material from the injection molding machine hopper into the barrel of the injection machine heated and rotation of the screw plasticizing melted, so that a uniform flow state melt viscosity, a high-pressure push the screw , the flow rate of the melt through the barrel in front of a large nozzle cavity injected into a high temperature, after a dwell time of feeding and crosslinking reaction, curing a shaped plastic parts, plastic parts and the mold removed. Thermoplastic injection molding process and compare the performance of the main differences in the melt into the mold after curing phase. Thermoplastic injection molding of plastic parts is a curing temperature from hot liquid to solid phase transformation of the physical processes; while thermoset injection molding of plastic parts curing but must rely on high pressure and temperature crosslinking chemical reaction. Because of this difference, resulting in two different process conditions, and thus its mold are different in structure.

 

! Plastic parts process analysis

 

Plastic as $ shows the bottle cap of the handle structure is used. The material is bakelite (CD): commonly known as bakelite. It is a widely used thermosets, its composition by adding a phenolic resin-based fiber or powder which consists of a variety of mold shrinkage was designed to take $ A! E, can be seen from the product structure, such as by injection molding process, to achieve automatic ejection of plastic parts, there must be two parting. I.e. with a diameter of! FG66 & bottom parting surface as to the central axis of the handle H parting plane, the position shown in FIG $. For H-parting flap must mold the structure. To shape! # 66 screw holes, you can use automatic withdrawal threaded body to achieve, but the cost of a larger mold, manufacturing difficulty is higher. To reduce tooling costs, ease of mold, you can use the activities threaded core inserts, the injection molding of plastic parts removed manually after the threaded core inserts removed from the plastic parts. With this structure, the overall structure of the mold is very simple, but also reduces the difficulty of manufacturing and shorten the molding cycle.

 

$ Mold design and working process

 

Mold structure shown! Shows. According to the requirements of production, mold using% modulus! Cavity structure. To meet the thermosetting plastic molding process, sprue and runner should be as short as required to achieve rapid filling to prevent the flow channel to generate early hardening, and can reduce the flow channel can not be recycled scrap purposes, & typing surface mold opening direction of the chosen direction shown in Figure%. In addition, core activities can also be placed in a given model inserts core, avoiding the active core inserts on the moving mold, mold process will lead to the active core inserts instability. Mold chosen standard mold, the model for! # $ # '& (' & Board $ "') board * #, and adds a support plate + to withstand thermosetting plastic in the molding process required high injection pressure, and is fixed inclined guide post $. Since the cured thermosetting plastic is injected at high temperature and pressure dependent on the crosslinking reaction, thus the temperature of the mold nozzle and barrel higher requirements than its mold temperature is cured thermoset plastic parts a key factor in shaping, molding quality is directly related to the level of quality and production efficiency. part of the requirements for the fixed mold mold temperature control in the% # ", -!!", while the dynamic model is required to control the% * "- ! $ #,. To this end in the mold of the fixed mold part, mold base plate% in fixed and fixed templates! Opened along the length between the two through slots; moving mold parts movable mold plate and the support plate + * between the width direction opened. strip through slots to install electric heating rods used. In order to ensure the injection molding of plastic parts dimensional accuracy requirements given model core inserts% / slider with a slider% are made of high toughness and heat resistance, good thermal die steel imports, steel purity Sweden Assab steel, steel model 012 & 1 +. "/. cavity surface roughness of!" "3.! 4, the surface hardness after quenching is #" - # # 516. Cavity surface using EDM manufacturing. To drain the thermoset injection plastic parts in the hardened stereotypes large amount of gas generated in the process, you need to parting surface of the slider along the cavity surrounding the opening few exhaust ducts, exhaust groove depth may be taken as "3" width +447 Take * 44. In order to prevent blocking exhaust ducts of the channel, after the mold is in the fixed template! # Required between the template and move left "3 + -% 44 of the gap, but it also ensures that the mold parting surface compression slider & After the slider and the slider% $ $ & parting surface can in close fitting, not & parting produce overflow phenomenon, of course, in order to ensure that no excess material here, after the mold clamping slider $, % $ slider plate and the movable die 'to be left between the "() *" (# + + clearance to the two sliders when closing the mold, the inclined pressure lamination, so that the two parting slider & no gap. die casting system including sprue, runner, pulling material cavity and gate. sprue from the sprue bush! "formation, shunt were opened along the parting surface model in action core inserts% 'with the slider and the slider $% $ on. put on in order to ensure the gate opened shunt model of the core inserts and fixed position on the line, the fixed gate sets, you should install anti-rotation of the cylindrical pin !%. pull material cavity open at two sliders parting on positive end of the sprue to collect material flow ahead of the front end due to local overheating hardening melt. pull material cavity made into inverted cone structure in order to After the injection molding mold sprue bush when out in the hardened sprue waste. pull material cavity due to open on the parting line, mold mold can be automatically separated out, without having to install the bottom to the top of the casting plunger Road waste.

 

Mold working process: the production of a good tool assembly to a dedicated horizontal thermosetting plastic injection machine, before the first thread forming mold core insert% 'into the given model core inserts%, in place when Note threaded inserts on the location, can not be put against. After closing the mold using the installation of electric heating rods in the mold the mold is heated to the desired temperature for injectable. Subject thermosetting plastic in the mold after curing, the movable die is moved backward to open the mold. In the process of mold, mold suppress off! # In the compression spring! $ Elastic force (spring force the size of the flat before this can be set screws!) To a suitable degree), push the slider back % $ $ and the slider, so that in the process of mold left in the dynamic model. At this point, the slider pull slug gate sets out the runner has been hardened waste threaded core inserts% 'is cured in plastic parts left in the slider inside. Followed by injection machine driven by fixed ejector rod fixed plate - and push plates% "between the putter, and then push the slider, the slider in the process of being pushed along the inclined guide post) to move and separated out, the plastic parts themselves from the slider. slider moves a distance from the screw%! fixed to the movable stopper on the template.%) is defined, to prevent the mold from the mold after the mold, such as a state diagram Figure) shows this time, the mold has completed an injection molding cycle again into the threaded core mold, the injection mold portion movable on the machine moves forward, the stationary platen! backpressure parting face of the slider and reset lever! (figure)), the pusher mechanism is reset, the mold clamping smoothly.

 

$ Molds in the injection molding process should pay attention to the problems of the

 

Thermosetting plastics injection molding process, the selection of process parameters is important. Especially for temperature control, direct impact on product quality and the molding cycle. The rear section of the injection machine (feed side) the temperature can be controlled in!. "*,.", Front (nozzle side) of the temperature to be controlled,. "* - #, Will have to control the temperature of the nozzle, # *% "." the mold temperature, the fixed mold part to control the% #. "*!!.", will have to control the movable mold part% '. "*!) #. Injection pressure to control the% "" *% "/ 01. Holding time taken%" *! "2 in the injection molding process with particular attention to the exhaust gas in addition to relying on the exhaust gas exhaust system, but sometimes also to unload pressure mold deflated. removed mold plastic parts, each time with a high-pressure air gun must also have hardened waste blowing particles into the gating system to prevent, hinder the forming mold filling process. Meanwhile, molds and molded plastic The temperature of the higher, when in operation shall wear a good heat-protective gloves to prevent hand burns.

 

Conclusion

 

Thermosetting plastic handle injection mold production has been running in production status. The mold structure using a disc mold and insert threaded core activities of the structure, the mold structure can be simplified to a great extent, the production proven, its structure is simple and practical, stable injection molding process.