With the rapid development of mold industry in recent years, the scope of application of new technologies, new technology continues to expand and progress to the application of the software development has been a qualitative change from the traditional experience accumulated. Mold and die market demand for products vary widely, and a wide range of CADCAM and CAE applications for a wide range of mold and mold geometry control technology has opened up room for growth in all aspects of the shape, size, material, structure, etc. changes, demanding, and allows us a lot of problems and difficulties encountered in the mold and production process, including how to effectively control the geometry of the mold and product is very intuitive on the front of us. Have different control techniques and methods for different types of molds and products. I am here today on the injection molding products forming size control talk a bit about experience, it comes to injection molding products must turn it comes to plastic injection mold, under normal circumstances, I proceed from the following aspects.http://www.prmindustry.com/Abstract...Articles section The control of a mold design
1, the first mold structure, material, hardness, precision waiting to fully understand the technical requirements of many users, including shrinkage of materials into the shape is correct, the 3D size modeling is complete, reasonable processing and analysis.
2, the shrinkage of injection molding products, flow marks, the slope of the dial mode, the weld lines and cracks, the appearance of affecting various parts of the full consideration.
3, without prejudice to the injection of product features and patterns form the premise, as far as possible to simplify the processing of the mold.
4, choose whether to appropriate the parting line, mold, forming the appearance and forming parts deburring must make careful choices.
Pushing the appropriateness of using the putter, the location of the stripper plate, jacking casing or the other way, putting and stripper plate whether it is appropriate.
6, the side core-pulling mechanism used is appropriate, flexible and reliable action, there should be no catching phenomenon.
7, temperature control how easy the plastic parts of products more suitable, whether it is appropriate to use what kind of structure of the temperature controlling oil, water, coolant circulation system which is the coolant hole size, number, location and so on.
8, the gate form, forehearth and the mouth of the feed size, gate location and size is appropriate.
9, various modules and heat deformation of the mold core impact and selection of standard parts.
10, injection molding machinery, injection volume, injection pressure and clamping force is fully match fit nozzle R, gate aperture.
These aspects of comprehensive analysis prepared from the product initial stage should be controlled strictly.
Two manufacturing process control
Full and complete consideration and arrangements at the design stage, but in actual production, there will be many problems and difficulties, we have to meet the original intent of the design in production as far as possible to identify more effective in the actual processing, more economical means of technology.
An economy to adapt to the machine equipment, for 2D and 3D processing program.
2, can also consider the appropriate fixture assisted in the production of preparations, the rational use of the tool to prevent the products of the deformation, to prevent fluctuations of product shrinkage, to prevent stripping deformation to improve the accuracy of the mold manufacturing, reduce errors and prevent mold precision change, a series of manufacturing process requirements and solutions.
3, here to mention the size of the error related to forming parts of the British Plastics Federation (BPF), the reasons for its proportion of the distribution:
A: The mold manufacturing error of about 1/3 B, the error caused by mold wear 1/6C by the inconsistency of forming pieces of uneven shrinkage error caused by about 1/3 D pre-shrinkage and shrinkage error of about 1/6
The total error = A + B + C + D, and therefore visible mold manufacturing tolerances of formed parts dimensional tolerance of 1/3, or the mold is difficult to guarantee the geometry of the forming parts.
Three are normally produced control
Plastic parts forming the geometric size of the fluctuations is a common problem, and is a frequently occurring phenomenon:
A melt temperature, mold temperature control, different grades of plastic necessary for the different temperature requirements, plastic liquidity and the use of more than two kinds of mixture will not happen, it should be plastic timber control in the best flow within the range of values, these are usually easy to do, but the mold temperature control is more complex, forming different pieces of geometry, size, wall thickness ratio of the different cooling deserves systems have certain requirements, mold temperature to a large extent control the cooling time, so try to make the mold to maintain low temperature can be allowed, in order to shorten the injection cycle, improve production efficiency, mold temperature changes, then the shrinkage will change the mold temperature to remain stable, dimensional accuracy is also stable , thereby preventing the deformation of the formed parts, bad luster, cool spots and other defects, the physical properties of plastics at its best, of course, there is a debugging process, especially in multi-cavity mold forming parts is more complex.
2, the pressure and exhaust adjustment control:
The injection pressure and clamping force of the match should be determined in debugging the mold in the mold cavity and core formation of the gap in the air and plastic gas from the exhaust ducts discharge the mold, such as row gas poor filling insufficient to produce a weld or burn, these three forming defects sometimes occasionally appear in the same area, forming wall portion of the parts book, surrounded by thick-walled exist, the mold temperature is too low there will be lack of filling and the mold temperature is too high you will burn phenomenon, usually in the burned area would appear to weld exhaust ducts are often neglected, are generally in a small state, usually does not produce a flash row the depth of the gas shroud as deep, the back of the shroud to open a larger ventilation slots in order to rapidly excreted through the shroud of gas can mold, special needs when in the open exhaust ducts on the mandrel, truth is the same, one does not waste side, two outlet fast well play an effect on the line.
3, injection molding to size supplementary shaping control
Some plastic parts after ejection due to the different shapes and sizes, with temperature and loss of pressure changes will occur in different situations the deformation warp, when some auxiliary fixture to be adjusted, in the shape of the pieces of the mold in a timely manner to take prompt remedial measures, let it will be able to achieve better correction after natural cooling setting, adjust the effect. If the entire injection molding process to ensure strict management, the size of the injection molding is the ideal control.
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2012-02-05
Injection molding processing, the pressure regulator
Either hydraulic or electric injection molding machine, the movement will have all in the injection molding process pressure. Proper control of the required pressure to produce quality finished. Pressure regulation and metering system in the hydraulic injection molding machine, all the movements performed by the responsible operation of oil:http://www.prmindustry.com/Abstract...Articles section A plasticizing stage rotary screw.
The two slide forehearth (nozzle close to the sprue bushing).
Injection and holding pressure during radio feed screw axial movement.
4 substrate closed injection rod or piston clamping stroke have been completed until toggle all.
The top five to start the assembly mandrel is introduced to the top of the parts.
In the full voltage on all sports with the implementation of a permanent magnet brushless synchronous motor. The rotational motion is transformed into linear motion by the machine tool industry has been using a ball bearing screw. The efficiency of the entire process depends in part on the plastination process in which the screw play a crucial role in Mitsubishi latest solutions in the production of the whole motor process, including a filling feed screw (threaded hold roller) and one with a screw tip of the mixing components. Thus, to maximize enhanced plasticizing capacity and mixing effect, shorten the screw length to achieve high-speed operation.
The screw must ensure that the materials melting and homogenization. This process can be by means of back pressure adjusted to avoid overheating. Mixing components can not generate excessive velocity, otherwise it may cause degradation of the polymer. Each polymer has a different maximum flow rate, if you exceed this limit, the molecule is stretched, the phenomenon of the polymer main strand breaks. However, the focus remains on the forward axial movement of the screw in the injection and holding pressure process. The subsequent cooling process, including the inherent stress tolerance and warpage and other aspects important to ensure product quality. It all decided by the quality of the mold, to ensure the effective closed-loop temperature control for optimizing the cooling forehearth, especially. The system is completely independent and does not interfere with mechanical adjustment. Closed mold and the ejector mold movement must be precise and efficient. Usually the velocity profile in order to ensure accurate close to the moving parts. Contact to maintain power adjustable. Therefore conclude that, under the premise does not consider energy consumption and mechanical reliability, the same additional conditions (such as the quality of the mold), product quality is mainly determined by the stage of the forward movement of the control screw the system. , This adjustment is achieved by detecting the hydraulic and hydraulic injection molding machine. Specifically, oil pressure through the control panel to activate a valve, the fluid by the manipulator, and to regulate and release.
The injection speed control, including the open-loop control, semi-closed loop control and closed-loop control options. Open-loop system relies on a shared proportional valve. The proportion of tension imposed on the proportion of fluid required, so that the fluid pressure in the injection barrel injection screw to the speed of movement to a certain former. Semi-closed loop system uses a closed-loop proportional valve. Closed loop location in the closed mouth, closed mouth by the movement within the valve to control the oil flow ratio. Closed-loop system is closed when the screw translation speed. Closed-loop system using a speed sensor (usually a potentiometer type), timing detection tension decreased. Proportional valve outflow of fuel through regulation, can compensate for the speed deviation. The closed-loop control rely on one of the special electronic components integrated with the machine. Closed loop pressure control in the injection and packing stages to ensure a uniform pressure, as well as ensure that the back pressure uniform in each cycle. Proportional valve to adjust the detected pressure value, depending on the value of the set pressure deviation compensation. In general, hydraulic monitoring, however, the probe nozzle or in the mold cavity melt pressure is another effective method. A more reliable program management by reading the pressure readings of the nozzle or cavity on the proportional valve. Increase the temperature probe, pressure probe on the basis of particularly conducive to the process management. Understanding of the material can withstand pressure, but also help to predict the actual weight of the molding and size according to the set pressure and temperature conditions. In fact, by changing the value of the holding pressure can be more material into cavity in order to reduce the contraction of parts to meet the design tolerances (including the default injection contraction).
Close to the melting conditions, the semi-crystalline polymer showing a great deal of specific volume change. In this regard, over the filling does not hinder parts ejection.
Hydraulic equipment and the quantity and material pressure regulator
The average hydraulic pressure generated by the centrifugal pumps up to 140 bar, this pressure is particularly suitable for injection molding. In various stages of the cycle, requiring significantly lower, in addition to the need to quickly plasticizing certain circumstances (for example: Note of PET stretch blow one-step injection molding machines) require a higher
In order to reduce energy consumption, can be used in discharging the peak of the variable displacement pump and accumulator tank. The fixed displacement pump to move the same amount of fuel in each rotation, so the pump selection by a specified period of time required to move the oil. Three-phase motor speed generally is 1440 rev / min, usually fitted with twin pumps. Only in the plasticizing process (power up to 100%), pump utilization to reach the maximum. Halt the process, the machinery does not require energy consumption, even if it takes, but also in the case of power loss.
All injection molding machines of varying quality and grade of proportional servo valve. Two or more of the proportional valve is installed in the injection press, the purpose is to accurately control the following aspects:
Mold opening speed (two), closed die speed (two), the closed mold safety, injection (3-10), feeding (3-5), inhalation, and the mandrel (two).
Mold pressure, closed mold pressure mold safety, mechanical fixture (barrel or toggle), injection (filling stage a follow-up stage 3-10), inhalation, and anti-pressure (3-5). Screw rotation speed (3-5).
Slide close to the speed (mechanical nozzle close to the speed of the mold fixed half-mold injection liner) and the plunger movement speed (the introduction of top speed) is also adjustable. Auxiliary motor through a weak input signal, the amplified signal (output signal) is sent to the valves, implementation of the regulatory function of the servo valve. In the servo valve, the weak input signal is converted into hydraulic output signals, to improve the form of a pressure drop according to the required discharge requirements. Valve must be tension or general instructions to make the material response of a rapid, reproducible and low hysteresis. In fact, the current research aimed at improving the frequency response, so running on a dialogue between the kilohertz (kHz) frequency of the power equipment (hydraulic side) and electronic equipment. Effective discharge depends on the role of the valve on the degree of polymerization (DP), the oil temperature in the hydraulic lines must be maintained within the range of 45-55 ° C (usually using the closed-loop regulation system), depending on the fluid viscosity and transition depending on the geometric shape of the mouth. Without proper conditioning system in the valve, rising temperatures will melt viscosity decreases; with balanced open threshold, you can increase the feeding amount. Increase the transmission system to discharge oil, means that the injection speed is facilitated. High-tech servo drive valve for precise control, and to basically eliminate the hysteresis, enhanced repeatability of all functions.
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The two slide forehearth (nozzle close to the sprue bushing).
Injection and holding pressure during radio feed screw axial movement.
4 substrate closed injection rod or piston clamping stroke have been completed until toggle all.
The top five to start the assembly mandrel is introduced to the top of the parts.
In the full voltage on all sports with the implementation of a permanent magnet brushless synchronous motor. The rotational motion is transformed into linear motion by the machine tool industry has been using a ball bearing screw. The efficiency of the entire process depends in part on the plastination process in which the screw play a crucial role in Mitsubishi latest solutions in the production of the whole motor process, including a filling feed screw (threaded hold roller) and one with a screw tip of the mixing components. Thus, to maximize enhanced plasticizing capacity and mixing effect, shorten the screw length to achieve high-speed operation.
The screw must ensure that the materials melting and homogenization. This process can be by means of back pressure adjusted to avoid overheating. Mixing components can not generate excessive velocity, otherwise it may cause degradation of the polymer. Each polymer has a different maximum flow rate, if you exceed this limit, the molecule is stretched, the phenomenon of the polymer main strand breaks. However, the focus remains on the forward axial movement of the screw in the injection and holding pressure process. The subsequent cooling process, including the inherent stress tolerance and warpage and other aspects important to ensure product quality. It all decided by the quality of the mold, to ensure the effective closed-loop temperature control for optimizing the cooling forehearth, especially. The system is completely independent and does not interfere with mechanical adjustment. Closed mold and the ejector mold movement must be precise and efficient. Usually the velocity profile in order to ensure accurate close to the moving parts. Contact to maintain power adjustable. Therefore conclude that, under the premise does not consider energy consumption and mechanical reliability, the same additional conditions (such as the quality of the mold), product quality is mainly determined by the stage of the forward movement of the control screw the system. , This adjustment is achieved by detecting the hydraulic and hydraulic injection molding machine. Specifically, oil pressure through the control panel to activate a valve, the fluid by the manipulator, and to regulate and release.
The injection speed control, including the open-loop control, semi-closed loop control and closed-loop control options. Open-loop system relies on a shared proportional valve. The proportion of tension imposed on the proportion of fluid required, so that the fluid pressure in the injection barrel injection screw to the speed of movement to a certain former. Semi-closed loop system uses a closed-loop proportional valve. Closed loop location in the closed mouth, closed mouth by the movement within the valve to control the oil flow ratio. Closed-loop system is closed when the screw translation speed. Closed-loop system using a speed sensor (usually a potentiometer type), timing detection tension decreased. Proportional valve outflow of fuel through regulation, can compensate for the speed deviation. The closed-loop control rely on one of the special electronic components integrated with the machine. Closed loop pressure control in the injection and packing stages to ensure a uniform pressure, as well as ensure that the back pressure uniform in each cycle. Proportional valve to adjust the detected pressure value, depending on the value of the set pressure deviation compensation. In general, hydraulic monitoring, however, the probe nozzle or in the mold cavity melt pressure is another effective method. A more reliable program management by reading the pressure readings of the nozzle or cavity on the proportional valve. Increase the temperature probe, pressure probe on the basis of particularly conducive to the process management. Understanding of the material can withstand pressure, but also help to predict the actual weight of the molding and size according to the set pressure and temperature conditions. In fact, by changing the value of the holding pressure can be more material into cavity in order to reduce the contraction of parts to meet the design tolerances (including the default injection contraction).
Close to the melting conditions, the semi-crystalline polymer showing a great deal of specific volume change. In this regard, over the filling does not hinder parts ejection.
Hydraulic equipment and the quantity and material pressure regulator
The average hydraulic pressure generated by the centrifugal pumps up to 140 bar, this pressure is particularly suitable for injection molding. In various stages of the cycle, requiring significantly lower, in addition to the need to quickly plasticizing certain circumstances (for example: Note of PET stretch blow one-step injection molding machines) require a higher
In order to reduce energy consumption, can be used in discharging the peak of the variable displacement pump and accumulator tank. The fixed displacement pump to move the same amount of fuel in each rotation, so the pump selection by a specified period of time required to move the oil. Three-phase motor speed generally is 1440 rev / min, usually fitted with twin pumps. Only in the plasticizing process (power up to 100%), pump utilization to reach the maximum. Halt the process, the machinery does not require energy consumption, even if it takes, but also in the case of power loss.
All injection molding machines of varying quality and grade of proportional servo valve. Two or more of the proportional valve is installed in the injection press, the purpose is to accurately control the following aspects:
Mold opening speed (two), closed die speed (two), the closed mold safety, injection (3-10), feeding (3-5), inhalation, and the mandrel (two).
Mold pressure, closed mold pressure mold safety, mechanical fixture (barrel or toggle), injection (filling stage a follow-up stage 3-10), inhalation, and anti-pressure (3-5). Screw rotation speed (3-5).
Slide close to the speed (mechanical nozzle close to the speed of the mold fixed half-mold injection liner) and the plunger movement speed (the introduction of top speed) is also adjustable. Auxiliary motor through a weak input signal, the amplified signal (output signal) is sent to the valves, implementation of the regulatory function of the servo valve. In the servo valve, the weak input signal is converted into hydraulic output signals, to improve the form of a pressure drop according to the required discharge requirements. Valve must be tension or general instructions to make the material response of a rapid, reproducible and low hysteresis. In fact, the current research aimed at improving the frequency response, so running on a dialogue between the kilohertz (kHz) frequency of the power equipment (hydraulic side) and electronic equipment. Effective discharge depends on the role of the valve on the degree of polymerization (DP), the oil temperature in the hydraulic lines must be maintained within the range of 45-55 ° C (usually using the closed-loop regulation system), depending on the fluid viscosity and transition depending on the geometric shape of the mouth. Without proper conditioning system in the valve, rising temperatures will melt viscosity decreases; with balanced open threshold, you can increase the feeding amount. Increase the transmission system to discharge oil, means that the injection speed is facilitated. High-tech servo drive valve for precise control, and to basically eliminate the hysteresis, enhanced repeatability of all functions.
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Plastic extrusion how to improve the dimensional accuracy
There is greater volatility in the extruder outlet pressure by a variety of factors will affect the dimensional accuracy of products, if we install a melt pump between exports and die of the extruder can be used to stabilize the extruder outlet pressure fluctuations, the linear extrusion possible to improve the output of the extruder, thereby improving the dimensional accuracy of plastic products, in unit time. The Haike melt pump is a positive displacement conveyor equipment, high-precision gear clearance and volume structure design, stable balanced extrusion made possible, in the chemical fiber granulator, plastic film, sheet, plate, extrusions, tubes The production line, wire and cable, wire drawing, composite extrusion, has been widely used to obtain fairly good results:http://www.prmindustry.com/
Abstract...Articles section To achieve stable extrusion to improve the extrusion products, dimensional accuracy, and reduce scrap. During the extrusion process, uneven material feeding quantity, the fluctuations of the barrel and die temperature, screw speed, the pulse phenomenon is difficult to avoid. Melt gear pump to eliminate the feeding of the feeding system error can be substantially reduced fluctuations in the upstream process passed quickly into the stable state, and improve the extrusion products, dimensional accuracy, and reduce scrap.
Increase production, reduce energy consumption, low-temperature extrusion, extend the life of the machine. Since the installation of a polymer melt pump to the extruder, extruder decompression functions transferred to the gear pump extruder in the low-pressure low-temperature state, the leakage flow is greatly reduced, production increased. The gear pump is easier than the extruder the establishment of head pressure and reduce the back pressure of the extruder screw to withstand the axial force decline and prolong life.
With linear extrusion characteristics, easy on the downstream equipment co-ordination. As the gear pump leakage less traffic, the transmission capacity and speed of the pump is basically a linear relationship between the gear pump speed changes, and its flow can know exactly, can determine the downstream device synchronization with the gear pump speed gear pump inlet pressure, temperature and other information collected by the exit of the entire extrusion process full-line monitoring and feedback control.
Control system adopts Siemens PLC programmable control mode, equipped with advanced man-machine interface, on pressure, temperature, flow, speed of a full range of control, worry-free switching of the automatic and manual control functions, the control system to the elimination of kinds of factors that cause pressure fluctuations of the extruder, the stable spout pressure to maximize the melt pump in the precision extrusion of advantages.
http://www.prmindustry.com/
Peter Huang
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Abstract...Articles section To achieve stable extrusion to improve the extrusion products, dimensional accuracy, and reduce scrap. During the extrusion process, uneven material feeding quantity, the fluctuations of the barrel and die temperature, screw speed, the pulse phenomenon is difficult to avoid. Melt gear pump to eliminate the feeding of the feeding system error can be substantially reduced fluctuations in the upstream process passed quickly into the stable state, and improve the extrusion products, dimensional accuracy, and reduce scrap.
Increase production, reduce energy consumption, low-temperature extrusion, extend the life of the machine. Since the installation of a polymer melt pump to the extruder, extruder decompression functions transferred to the gear pump extruder in the low-pressure low-temperature state, the leakage flow is greatly reduced, production increased. The gear pump is easier than the extruder the establishment of head pressure and reduce the back pressure of the extruder screw to withstand the axial force decline and prolong life.
With linear extrusion characteristics, easy on the downstream equipment co-ordination. As the gear pump leakage less traffic, the transmission capacity and speed of the pump is basically a linear relationship between the gear pump speed changes, and its flow can know exactly, can determine the downstream device synchronization with the gear pump speed gear pump inlet pressure, temperature and other information collected by the exit of the entire extrusion process full-line monitoring and feedback control.
Control system adopts Siemens PLC programmable control mode, equipped with advanced man-machine interface, on pressure, temperature, flow, speed of a full range of control, worry-free switching of the automatic and manual control functions, the control system to the elimination of kinds of factors that cause pressure fluctuations of the extruder, the stable spout pressure to maximize the melt pump in the precision extrusion of advantages.
http://www.prmindustry.com/
Peter Huang
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