The tools and products we use in daily production and life range from the base of the machine tool to the outer casing of the machine, to a small screw, button and shell of various household appliances, all of which have a close relationship with the mold. The shape of the mold determines the shape of these products, and the quality and precision of the mold determines the quality of these products. Because of the different materials, appearance, specifications and uses of various products, the mold is divided into casting molds, forging dies, die-casting dies, stamping dies and other non-plastic molds, as well as plastic molds, of which plastic molds are used. In recent years, with the rapid development of the plastics industry and the continuous improvement of the strength and precision of general and engineering plastics, the application range of plastic products is also expanding, such as: household appliances, instrumentation, construction equipment, automobile industry, day In many fields such as hardware, the proportion of plastic products is increasing rapidly. A well-designed plastic part can often replace multiple traditional metal parts. The trend of plasticization of industrial products and daily-use products is on the rise. Do you want to know more about the plastic mold? The following DEXUAN will introduce the plastic mold structure and plastic mold design process. Let’s take a look!
Plastic mold structure and plastic mold design process
First, the plastic mold structure is divided into functions, mainly consisting of: pouring system, temperature control system, molded part system, exhaust system, guiding system, ejection system and so on. The gating system and the molded part are in direct contact with the plastic and vary with the plastic and the product. It is the most complicated and most varied part of the mold, and requires the highest degree of smoothness and precision.
1. Gating system: refers to the part of the flow channel before the plastic enters the cavity from the nozzle, including the main channel, cold material hole, shunt channel and gate.
2. Molded parts system: refers to the various parts and components that make up the shape of the product, including dynamic mold, fixed mold and cavity (concave mold), core (protrusion), forming rod and so on. The core forms the inner surface of the article and the cavity (female) forms the outer surface shape of the article. After clamping, the core and cavity form the cavity of the mold. According to the process and manufacturing requirements, sometimes the core and the die are made up of several pieces, sometimes made into a whole, and only the inserts are used in the parts that are easily damaged and difficult to process.
3. Temperature regulation system: In order to meet the requirements of the injection process on the mold temperature, a temperature adjustment system is required to adjust the temperature of the mold. For injection molds for thermoplastics, the cooling system is primarily designed to cool the mold (the mold can also be heated). The common method of mold cooling is to open a cooling water channel in the mold, and use the circulating cooling water to remove the heat of the mold; the heating of the mold can be done by using hot water or hot oil in the cooling water, and can be installed inside and around the mold. Electric heating element.
4. Exhaust system: It is set up to remove the gas generated by the melting of air and plastic in the cavity during injection molding, and the gas is formed on the surface of the product when the exhaust gas is not smooth. Poor; the exhaust system of the plastic mold is usually a slot-shaped air outlet opened in the mold to discharge the gas of the original cavity air and the melt.
When the molten material is injected into the cavity, the air originally stored in the cavity and the gas brought in by the melt must be discharged to the outside of the die through the exhaust port at the end of the flow, otherwise the product will have pores and poor connection. The filling is not full, and even the accumulated air burns the product due to the high temperature generated by compression. In general, the vent hole can be located at the end of the flow of the melt in the cavity or on the parting surface of the mold.
The latter is a shallow groove having a depth of 0.03-0.2 mm and a width of 1.5-6 mm on one side of the die. During the injection, the vent hole does not have a lot of melt oozing out, because the melt will cool and solidify there to block the passage. Do not point the opening of the exhaust port to the operator to prevent the fuse from accidentally squirting and injuring people. In addition, the matching gap between the ejector rod and the ejector hole, the matching gap between the top block and the stripping plate and the core may be utilized to exhaust.
5. Guide system: It is to ensure that the dynamic mold and the fixed mold can be accurately centered during mold clamping. Guide parts must be set in the mold. In the injection mold, four sets of guide columns and guide sleeves are usually used to form the guide members, and sometimes the inner and outer tapered surfaces are respectively arranged on the movable mold and the fixed mold to assist the positioning.
6, ejection system: generally includes: thimble, front and rear ejector plate, thimble guide, thimble return spring, thimble plate locking screws and other parts. When the product is molded and cooled in the mold, the front and rear molds of the mold are separated and opened, and the plastic product and its aggregate in the flow passage are pushed out or pulled out of the mold opening and flow path position by the pushing mechanism-the ejector pin under the push rod of the injection molding machine. In order to carry out the next injection molding work cycle.
our product-Reusable Airline Plastic Coffee Bottle Water Jug
Second, the plastic mold is generally composed of mold parts, mold cores, auxiliary parts, auxiliary systems, auxiliary settings, dead angle processing mechanisms, etc. according to the structure.
1, mold base: generally do not need our design, can be ordered directly from the standard mold frame manufacturers, greatly saving the time required to design the mold, so it is called the plastic mold standard mold base. It forms the most basic part of the plastic mold.
2, mold kernel: mold part is the core part of the plastic mold, it is the most important part of the mold. The molded part of the plastic product is in the mold core, and most of the time is also processed on the mold core. However, compared to some simple molds, it has no mold part and the product is formed directly on the template. Most of the early plastic molds were so relatively backward.
3. Auxiliary parts: Common auxiliary parts for plastic molds include positioning ring, nozzle bushing, thimble, grab pin, support column, guide plate guide bush, garbage nail, etc., some of which are standard parts. Order directly when ordering the formwork, and some of them need to be designed by yourself.
4. Auxiliary system: There are four auxiliary systems for plastic molds: pouring system, ejection system, cooling system and exhaust system. Sometimes, because the plastic material used needs to be heated at a high temperature, some heating systems exist in some molds.
5, with the help of settings: plastic mold with the help of the ring hole, KO hole (top stick hole) and so on.
6, dead angle treatment structure: When the plastic product has a dead angle, the mold will have one or more structures to deal with dead angles. Such as sliders, inclined tops, hydraulic cylinders, etc. In most books in China, the mechanism for dealing with dead ends is called the "spinning mechanism".
In fact, the plastic mold is not difficult, no matter how the plastic product changes, for the mold to form the plastic product, its structure is nothing more than the above aspects. The difference between the molds is whether the mold is large or small? The location or method of each auxiliary part, auxiliary setting, and auxiliary system is different. The method, structure, size, etc. of handling dead angles have changed. Of course, the design experience is particularly important in order to make the designed mold simple, easy to assemble, long life, moderate price, and good forming products. Good experience can deal with problems in design and processing, and it is more sure to deal with changes.
Third, the injection machine's structural composition: a general-purpose injection machine mainly includes injection device, clamping device, hydraulic transmission system and electrical control system. The main function of the injection device is to plasticize the plastic evenly and inject a certain amount of melt into the cavity of the mold at a sufficient pressure and speed. The injection device is mainly composed of a plasticizing component (composed of a screw, a barrel and a nozzle), a hopper, a transmission device, a metering device, an injection and a moving oil cylinder, and the like.
1. Clamping device: its function is to realize the opening and closing of the mold, to ensure the forming mold is reliably tightened during the injection, and to take off the product. The clamping device is mainly composed of the front and rear fixed template, the moving template, the connecting rod for connecting the front and rear templates, It is composed of a mold cylinder, a link mechanism, a mold adjustment device, and a product ejection device.
2, hydraulic system and electrical control system: its role is to ensure that the injection machine according to the process requirements (pressure, speed, temperature, time) and the sequence of actions accurate and effective work. The hydraulic system of the injection machine is mainly composed of various hydraulic components and circuits and other ancillary equipment. The electrical control system is mainly composed of various electrical appliances and instruments. The hydraulic system and the electrical system are organically organized to provide power and realization to the injection machine. control.
our product-Inflight Heat Resistant Custom Logo ABS Plastic Airline Tableware Set
Plastic mold design process
First, accept the task book
The task book for molded plastic parts is usually proposed by the part designer, and its contents are as follows:
1. The drawings of the formal parts that have been examined and signed, and indicate the grades and transparency of the plastics.
2. Plastic parts specifications or technical requirements.
3. Production output.
4. Samples of plastic parts.
Usually, the mold design task book is proposed by the plastic parts craftsman according to the task book of the molded plastic parts. The mold design personnel design the mold based on the molded plastic parts task book and the mold design task book.
Second, collecting, analyzing and digesting the original data
Collect and organize related parts design, molding process, molding equipment, machining and special processing materials for use in designing molds.
1. Digest the plastic parts drawing, understand the use of the parts, analyze the technical requirements of the plastic parts, dimensional accuracy and other technical requirements. For example, what are the requirements for the appearance, color transparency, and performance of plastic parts, whether the geometrical structure, slope, inserts, etc. of the plastic parts are reasonable, the allowable degree of molding defects such as weld lines and shrinkage holes, and whether or not they are coated Post-processing such as loading, plating, gluing, drilling, etc. Select the size of the plastic part with the highest dimensional accuracy for analysis to see if the estimated molding tolerance is lower than the tolerance of the plastic part, and whether the desired plastic part can be formed. In addition, it is necessary to understand the plasticization and molding process parameters of plastics.
2. Digestion of process data, analysis of the requirements of the molding method, equipment model, material specification, mold structure type, etc. proposed in the process task book, whether it can be implemented. The molding material should meet the strength requirements of plastic parts, with good fluidity, uniformity, isotropy and thermal stability. Depending on the use of the plastic part, the molding material should meet the requirements for dyeing, metallization, decorative properties, necessary elasticity and plasticity, transparency or reverse reflection properties, adhesive properties or weldability.
3. Determine the molding method
Whether it is a direct pressure method, a casting method or an injection method.
4, choose molding equipment
The mold is carried out according to the type of molding equipment, so it is necessary to be familiar with the performance, specifications, and characteristics of various molding equipment. For example, for the injection machine, the following should be understood in terms of specifications: injection capacity, mold clamping pressure, injection pressure, mold mounting size, ejection device and size, nozzle hole diameter and nozzle spherical radius, gate sleeve positioning ring size, The maximum thickness and minimum thickness of the mold, the stroke of the template, etc., see the relevant parameters. To initially estimate the mold dimensions, determine if the mold can be installed and used on the selected injection machine.
5, the specific structure of the program
(1) Determine the mold type
Such as pressing die (open, semi-closed, closed), casting die, injection mold, and the like.
(2) Determine the main structure of the mold type
Choosing the ideal mold structure is to determine the necessary molding equipment, the ideal number of cavities, and under the absolutely reliable conditions, the work of the mold itself can meet the requirements of the process technology and production economy of the plastic parts. The technical requirements for plastic parts are to ensure the geometry, surface finish and dimensional accuracy of the plastic parts. The economic requirement of production is to make the cost of plastic parts low, the production efficiency is high, the mold can work continuously, the service life is long, and labor is saved.
The article is long and divided into two parts. If you want to continue to know, please keep an eye on our update.
Thank you for reading, I wish you a happy life, if you like our products, you can contact us online or by email.