When designing a Furniture Mould(FURNITUREMOULD), after determining the mould structure, each part of the furniture mould can be designed in detail, ie the size, cavity and core size of each template and part are determined. This will involve major design parameters such as material shrinkage. Therefore, the size of each portion of the cavity can only be determined by specifically grasping the shrinkage of the shaped plastic. Even if the selected furniture mould structure is correct, it is impossible to produce qualified plastic parts if the parameters used are not correct.
Thermoplastics are characterized in that they expand upon heating, shrink after cooling, and of course the volume shrinks after pressurization. In the injection moulding process, molten plastic is first injected into the cavity, and after the filling is completed, the melt is cooled and solidified, shrinkage occurs when the plastic part is taken out of the furniture mould, and is called shrinkage forming shrinkage. The size of the plastic parts will vary slightly from the furniture mould to the steady state. One change is to continue to shrink. This contraction is called contraction. Another variation is that some hygroscopic plastics swell due to moisture absorption.
For the wall thickness of the formed part, the shrinkage rate is also large due to the long cooling time of the thick wall, as shown in FIG. For a general plastic part, when the flow direction L size, the difference between the melt and the dimension W perpendicular to the melt flow direction is large, the difference in shrinkage ratio is also large. From the flow distance of the melt, the pressure loss away from the gate portion is large, so the shrinkage rate at this time is also larger than the shrinkage ratio in the vicinity of the gate portion. Due to the resistance to shrinkage of the ribs, holes, bosses and engravings, the shrinkage of these parts is small.
The plastics industry has been very agile for the past 20 years. As early as seven years ago, the annual output of plastics exceeded the annual output of steel and non-ferrous metals. It is widely used in various related categories. There are many ways in which Air Cooler Mould(FURNITUREMOULD)plastic products, but the most important method is injection moulding.
With the increasing complexity and precision requirements of plastic products and the shortening of production cycles, traditional air cooler mould design methods cannot meet market requirements based on experience. In large complex small precision injection moulds, China still needs to import from abroad.
The traditional injection moulding simulation software is based on the finished intermediate layer mould. The user first abstracts the thin-walled plastic product into an approximate plane and surface, called the intermediate layer. Two-dimensional planar triangular meshes are generated on these intermediate layers, and these two-dimensional planar triangular meshes are used for finite element calculations, and the final analytical results are displayed on the intermediate surface. Most of the injection moulding moulds use three-dimensional solid moulds, because the two models are different and cannot prevent secondary moulding. However, extracting intermediate levels from 3D solids is a daunting task due to the complex and variable shape of the injection moulded product. The extraction process is cumbersome and time consuming, so designers are concerned about simulation software, which has become injection moulding simulation software. Promote the use of bottlenecks.
Table Mould(FURNITUREMOULD) injection deformation, bending and twisting phenomenon is mainly due to shrinkage of the plastic flow direction is greater than vertical, the anisotropy shrinkage of each part is different, because the warpage of injection moulding is part of the residual internal stress is unavoidable due to large warpage, here It is the cause and solution for the warpage and deformation of plastic injection moulding.
1. Insufficient cooling or uneven
When not fully cooled, the top thrust of the mandrel tends to deform the component, so it deforms if the component is not sufficiently cooled. The solution is to adequately cool in the mould cavity and then fully harden before it can be pushed out. It also reduces table mould temperature and extends cooling time.
2. Caused by forming strain
The deformation caused by the forming strain is mainly caused by the difference in the shape shrinkage in the direction and the change in the wall thickness. Therefore, by increasing the table mould temperature, increasing the melting temperature, lowering the injection pressure, and improving the flow conditions of the casting system, the difference in direction shrinkage can be reduced.
3. Rod caused
Some parts are not properly demolded, and the ejector is used to force the demoulding to deform. Plastic parts that are not easily deformed will not deform at the same time, but cracks will occur. The elimination method is to improve the polishing of the table mould, making it easy to release, and sometimes using the release agent to improve the mould release property.
4. Correct product warpage
If it is necessary to correct the product removed from the table mould, the simple method is to calibrate the product and add weight to the correction tool, but the weight of the weight must be clearly determined. Or place the warped product on the straightener and place it in hot water close to the heat distortion temperature of the product and straighten it by hand. However, it should be noted that the temperature of the hot water should not be too high, otherwise the deformation of the product will be more harmful.
Steel is the decisive factor in the quality of Air Cooler Mould(FURNITUREMOULD), and choosing the right steel is a top priority. The criteria for choosing steel are:
1. Requirements for injection moulding materials - Different plastics should use different steels, such as high polishing and corrosion resistance.
2. Price - steel can be used, not the more expensive the better; considering the cost of the mould, the mould steel should use the material corresponding to the life of the mould to avoid unnecessary waste; the life of the general P20 is about 300,000; 2738 500,000 is no problem, H13 / 2344 usually exceeds 80-100 million, and can be selected according to the situation.
3. Heat treatment. The surface treatment of the mould is also very important. Nitriding - can improve the surface hardness of steel, effectively extend the life of the mould; electroplating - can effectively modify the mould steel, for some high-brightness and corrosion-resistant plastic parts can use electroplating to enhance and improve the performance of steel.
The mould company tells you that Table Mould(FURNITUREMOULD) processing has the following basic characteristics:
The machining accuracy is high. A pair of moulds generally consists of a die, a punch and a die, and some may be more split modules. Therefore, the combination, the lower die, the combined block and the cavity, require high machining accuracy to separate between the modules.
In small batches, mould production is not produced in batches, and in many cases it is often only produced one.
The shape is complicated, and some products such as automobile parts, aircraft parts, toys, household appliances, the surface shape is determined by various curved surfaces, and therefore, the cavity surface is very complicated. Some surfaces must be processed mathematically.
Process, table mould processing must use milling, boring, drilling, reaming and tapping. High hardness, excellent mould material, the main material of the mould is made of high quality alloy steel, especially the long life of the mould, often using Crl2, CrWMn and Leysite steel. This forged, machined and heat treated steel has stringent requirements.
Repeated operation, when using a table mould is to use a mould during its service life, it must be replaced with a new mould, so mould production is usually repeated.
Sectional drawings, sometimes without pattern mould production, no data, and processing materials according to profiles. This requires imitation precision and no distortion.
Different types of Chair Mould(FURNITUREMOULD), different types of moulded plastics (same type of mould), different assembly methods vary with different start and precision requirements. Therefore, the assembly drawing and part drawing should be carefully studied before assembly. Determine the assembly baseline by understanding the function, characteristics, and technical requirements of each component. After careful assembly, all quality indicators of the product have been achieved, including the accuracy of the mould movement and other technical requirements during use.
Assembly data refers to the data used to determine the relative position of parts or components in a product during assembly. It can be broadly divided into:
(1) Main working parts, such as cores, cavities and inserts, shall be used as assembly reference parts;
(2) Take the template side base surface of the guide sleeve or mould as the assembly base surface.
2. Assembly accuracy
Assembly accuracy refers to geometric accuracy, machining accuracy, and motion accuracy after assembly. The assembly accuracy of the chair mould includes:
(1) mutual accuracy of each part, such as distance dimensional accuracy, coaxiality, equality, verticality, etc.;
(2) Relative motion accuracy, such as transmission accuracy, linear motion and rotational motion accuracy;
(3) matching accuracy and contact accuracy, such as matching gap and overflow contact conditions;
(4) The wall thickness of the plastic moulded part. When manufacturing a new mould, the wall thickness of the moulded part should deviate from the lower limit of the size.
Air Cooler Mould(FURNITUREMOULD) processing equipment needs to improve processing performance, mainly reflected in:
1. The air cooler is getting bigger and bigger, the production requirements of parts are getting higher and higher, the mould cavity is getting bigger and bigger, the air cooler mould is getting bigger and bigger, and the cavity needs very good air cooler mould processing equipment. , increase YZ axis travel, large bearings, high rigidity, high consistency.
2. The air cooler mould material has high hardness and requires air cooler mould processing equipment with thermal stability and high reliability.
3. Complex cavity and multi-functional composite moulds, as complex shaped parts, must improve the level of air cooler mould design and manufacturing, various grooves, various materials in plastic boxes to wash or assemble components in the air In the cooler mould, a large number of machining programming programs are required, which have high deep cavity overall cutting ability and high stability, and improve processing difficulty.
4. The refinement of air cooler mould processing makes the high efficiency of composite processing equipment more attractive. High-speed milling has the advantages of high hardness, stable processing, small cutting force, small workpiece temperature and deformation, which makes air cooler mould enterprises pay more and more attention to high-speed machining.
5. High dynamic accuracy. Static performance introduced by machine tool builders (such as repeatable positioning accuracy and linear feed rate) does not reflect the actual machining conditions of the 3D surface treatment of air cooler mould. The precision machining of 3D surface air cooler mould requires high-precision dynamic performance, high speed and high precision, and combined quality control systems are possible in high rigidity, high thermal stability and high reliability machine tools.
The Chair Mould(FURNITUREMOULD) operates at relatively high temperatures, such as 80 degrees Celsius or 176 degrees Fahrenheit. If the chair mould is not insulated, the air and the injection machine lose as much heat as the injector cylinder.
Therefore, you need to insulate the chair mould frame and, if possible, insulate the chair mould surface. If you are considering using a hot runner mould, try reducing the heat exchange between the hot runner section and the cooling injection mould. This method can reduce energy loss and warm-up time.
In general, higher chair mould temperatures reduce the amount of plastic that condenses within the mould cavity, making it easier for the molten material to flow within the mould cavity, resulting in greater part weight and better surface quality. At the same time, the mould temperature increases the tensile strength of the part.
In many injection moulding machines, this naturally means that the flow rate through the gate and the cavity is faster because the injection flow control valve used cannot correct this change, and the faster filling in the flow channel and cavity causes higher Effective pressure.
The development of the industry shows that the knowledge-related knowledge transmission rate will become lighter and lighter. Here are the advantages of Chair Mould(FURNITUREMOULD) injection and blow moulding:
(1) When the melt is injected into the cavity of the chair mould, there is a certain orientation effect in the circumferential direction. In addition, the temperature of the billet is lower than the temperature of the extrusion blow, and the orientation effect by the blowing can be more maintained, which contributes to the strength and other properties of the container.
(2) High dimensional accuracy of the container (especially the size of the neck thread): It is easier to ensure uniform wall thickness and uniform container size according to requirements.
(3) No seams are formed on the container, no trimming is required, and no residual material is generally produced (the remaining material produced by extrusion blow moulding is usually 5% to 30%).
(4) The container has a high gloss, and the container formed of the transparent polymer is always transparent.
(5) The sliding bottom module can be placed on the blow moulding machine mould, so the shape of the bottom shape of the container is more flexible.
(6) More suitable for rigid plastic containers and wide mouth containers.