Automotive and consumer products industry on the injection of increasingly stringent quality requirements, so the injection molding process has made new demands put forward, without weld lines, shorter injection molding cycles and higher precision,glue stick while the mold temperature control technology will make it all processing problems solved.
Seamless surface, shorter injection molding cycles and high accuracy - these three challenges,glue gun the need to develop a special injection molding cooling, mold temperature control is an efficient solution.
Mold temperature control tools.
Mold temperature control means that the mold temperature is not constant, but in an injection cycle, the temperature curve according to the definition of control. Injection, the temperature almost as high as the temperature of the injected material; injection, the mold will need to quickly cool down to fast-curing materials. Therefore, the use of this technology, it is possible to produce any flow line, high-gloss surface deformation of the plastic parts.
There are many techniques to achieve mold temperature control, such as the use of two cooling circuits (steam / water or oil / oil), liquid cooling combination with induction heating, infrared heating combined with liquid cooling, or heating with electric heating elements and liquid combined cooling, and high-performance ceramics CPH dynamic mold temperature control technology or two cycles of precision temperature control.
There are many techniques to achieve mold temperature control, such as the use of two cooling circuits (steam / water or oil / oil), liquid cooling combination with induction heating, infrared heating combined with liquid cooling, or heating with electric heating elements and liquid combined cooling, and high-performance ceramics CPH dynamic mold temperature control technology or two cycles of precision temperature control.
Implementation of injection molding the need to create dynamic temperature profile close to the temperature of the mold groove to rapid heating and cooling. Taking into account the different thickness around in different areas of the workpiece, heat transfer in different ways. The more cooling channels or through the mold cavity closer, more accurate adjustment of the cooling process. Provided that each channel has its own temperature control cooling. For smaller tools, the channel is located in the cavity of 1.5 mm. Two halves of the mold by large established along the tools needed to open the outline of a long temperature control channel.
Closed cavity temperature control.
Mold temperature control and short cycle time demands some degree of conflict photogenic, but this conflict can be like a "sub-tool temperature control," or Lasercusing (CONCEPT laser technology company's patented technology) and other new technologies to solve. Using these techniques, the cooling channel will be very close to the mold cavity, the mold can be implemented in order to get the ideal three-dimensional channel structure of the cooling channel configuration.
Close temperature control by measuring the temperature of the mold cavity or measuring the temperature of the coolant return achieved. Thermocouple or resistance thermometer is usually used, such as for sensors with PT100 to measure the current temperature, and that this information is passed to a controller, and then adjust each channel the flow of coolant. Control means is injected steam or hot water heating, water cooling. This greatly improved the surface quality of temperature control type, and shorten cycle time.
Valve technology innovation.
Proportion of new developments in solenoid valves in parallel multi-loop temperature control circuit to be implemented. The valve has the advantage of non-friction bearings used in the core, and through the special form of spring to avoid the stick-slip effect. This can be reflected through the excellent record, including the most important response sensitivity (accounting for 0.1% of final value), the smallest error and excellent reverse regulation performance. The new measurement range of 1:100 solenoid valve, which allows it to adapt to even very subtle changes in temperature, such as corrective action caused by the valve is very subtle changes.
Cooling process used to measure the workpiece is to return the value of the decisive test of temperature and water flow, it helps with absolutely reliable and accurate way to adjust the cooling liquid.
"For each cooling channel must be measured return temperature, which must have a valve and a sensor to measure, in order to increase the intensity of temperature regulation is also necessary to control the flow rate and flow temperature." Bürkert Fluid Control Systems Process Engineer Dr. EgonHüfner explained. The most advanced sensors 100 to 300 milliseconds to detect changes between the control valve 0.3 to 1 second to adjust flow. Wheel sensor (Impellersensors) is particularly suitable because of their small frame size and excellent response time.
Actuator works.
Valve selection depends on the coolant flow and pollution. "If the high flow rate and pollution of the liquid, the valve is recommended directly. If the temperature up to 180 ℃, air operated On / Off or control valve is appropriate." Hüfner said Dr.. According to loss of heat, if you want to control the valve open time, the cooling stages in injection molding using on / off temperature control or pulse cooling.
For low flow and clean the cooling liquid, if the central water treatment equipment, and the water temperature below 90 degrees Celsius, the servo-assisted solenoid valve is very good. Despite being a small vent, and its nominal diameter up to 20mm. Bürkert latest generation of the On / Off valve in the diaphragm there is no vent, so the dirty liquid cooling is not suitable.
More or less depending on the nature of the workpiece for cooling, the use of multi-channel temperature control, the use of pneumatic control valve, directly or servo-assisted solenoid valve, provide a clear advantage. They can quickly crack width adjustable from 0-100%. This technology enables the dynamic control valve can be pre-set temperature curve according to the workpiece. Quickly realize the temperature control to protect and enhance the durability of the valve. Using pneumatic control valve, nominal diameter of the fluid pressure is not subject to restrictions. It is generally range from 4 to 20 mm, or even higher. To adjust a particular crack width, requires a complementary electronic control. This ratio control valve is adjusted through the pulse (PWM) to achieve. Relative to the normal process control valves, which is a combination of valve position control by the auxiliary control valve positioners. It is adjusting the process valve piston to a specific crack opening.
Distributed mold temperature control.
Typically, the integration process system includes a flow sensor, proportional valves and flow controllers. The controller in the system play a decisive role, because it must be able to handle different sensor signals, such as temperature, pressure or flow, and must be able and pneumatic and electric control system to communicate.
Bürkert's next-generation universal controller eCONTROL meet all these requirements, the most important features are: temperature control; pressure control; flow control; control On / Off solenoid valves, proportional valves, process control valves and electric control valve; input normal sensor signal (standard signal 4 to 20mA, frequency, PT100); for the set point with a 4-20mA communications with the central control unit, processing the value of feedback; according to the selected application (flow, temperature or pressure control) to easily set up; Memory Most Bürkert valves and sensor data. eCONTROL also made a hole in the panel by 1/16DIN standard form, and integration into existing control cabinet. Distributed system simplifies machine mold temperature control, allowing them to focus on their tasks properly.