Industry information

Plastic mold design

2021-06-24

Plastic mold design

Mold designers must be carefully designed according to the basis and requirements provided by customers,

Timing, the above requirements are identified by one, and it is expressed in the form of a drawing or technical document. Its design process basics

It is performed in the following procedure.

1. For plastic products graphs and the active analysis and digestion

Before performing mold design, first analyze and digest the product diagram or the actual sample, including the following

Aspect:

(1) Geometric shape of the article;

(2) Dimensions, tolerances and design references

(3) Technical requirements (ie technical conditions);

(4) Plastic name used by the product;

(5) Surface requirements of products

2. Determination of the syringe model

The determination of the syringe specification is mainly based on the size and production volume of the plastic product. When the designer is selected when selecting a syringe, it mainly considers the effective area of its plasticity, injection volume, and the mounting force (inner spacing of the injective pulley), the capacity of the injector.

Form and top out of length. If the customer has provided the model or specification of the syringe used, the designer must perform its parameters.

If you don't meet the requirements, you must replace it with the customer.

3. Determination of the number of cavities and cavity arrangements

The determination of the number of mold cavities is mainly based on the projected area of the article, the geometric shape (there is no side extraction core), the product accuracy,

Batch and economic benefits are determined.

The number of cavities is mainly based on the following factors:

(1) The weight of the product and the injection amount of the injection;

(2) The projection area of the article and the latching force of the syringe;

(3) Mold shape size and effective area of the injection machine mounting mold (or injective pitch of the injection machine);

(4) Product accuracy;

(5) Product color;

(6) The article has a surfaceless core and its treatment method;

(7) Production batch (monthly batch or annual batch);

(8) Economic benefits (each model of production).

These factors are sometimes constrained, so they must be coordinated when determining the design, ensuring satisfaction

Its main conditions.

After the number of cavities is determined, the arrangement of the cavity is performed, that is, the arrangement of the cavity position. The arrangement of cavity involves mold rules

Inch, pouring system design, pouring system balance, core (slider) mechanism design, insert and core design and

Design of the heat exchange system. These problems are related to the selection of the layout and gate position, so in a specific design process

In, to make the necessary adjustments to achieve a relatively perfect design

4. Determination of the division

Fortified surface, has made specific provisions in some foreign product pictures, but in a lot of mold designs to be designed by the mold

Come to determine. In general, the division surface on the plane is relatively easy to handle, and sometimes it should be in the three-dimensional formation of the form.

pay attention. The choice of its division should follow the principles of the following:

(1) Does not affect the appearance of the article, especially those with clear requirements of the appearance, and should pay more attention to the face of the appearance.

influences;

(2) Help to ensure the accuracy of the article;

(3) It is conducive to mold processing, especially the processing of cavity;

(4) It is conducive to the design of the casting system, exhaust system, cooling system;

(5) It is conducive to the demolding of the article, ensuring that the article is left on the side of the moving model when molded;

(6) Easy to install the metal insert.

5. Determination of lateral derivation and core mechanism

When designing a side-by-side system, it should be ensured that it is safe and reliable, and it is necessary to avoid interference with the top outlet, otherwise the first reset mechanism should be set on the mold.

6. Design of pouring system

The design of the pouring system includes the mainstream selection, the sorting of the partial cross-sectional shape and the size of the gate, the selection of gate positions, pour

Determination of the form of the mouth and the sizes of the gate. When a point gate is used, in order to ensure the fall of the split, it should also be noted that the design of the devasting port is designed, first is the position of the gate. The appropriate or not the gate position selection will be directly related to the molding quality of the article and whether the injection process can be smooth. The choice of gate position should follow the following principles

(1) The gate position should be selected to be selected on the division, in order to clean the mold processing and use of the gate;

(2) The distance between the gate positions of the gate position should be as consistent, and its process is the shortest;

(3) The position of the gate should ensure that the plastic flows into the cavity, and the thickness of the cavity is wide and thick in the plastic.

Flow into;

(4) Avoid plastic straight-type cavity walls, cores or inserts, so that plastics can flow into the cavity as soon as possible

Bit, and avoid core or insert deformation;

(5) Try to avoid the production of the article to generate a fusion mark, or make its fusion mark in an inemodable site;

(6) The gate position and its plastic inflow direction should make the plastic in the flow of the cavity, and can be uniform along the cavity.

Inflow, and facilitate the discharge of gas in the cavity;

(7) The gate should be set to the most easily removed portion on the product while do not affect the appearance of the article as much as possible.

7. Design of exhaust system

The exhaust system has a crucial role in ensuring product molding, and its exhaust mode has the following

(1) Use the exhaust tank. The exhaust tank is generally provided in the final portion of the cavity. The depth of the exhaust tank differs from plastics

The different is basically determined by the maximum gap allowed when the plastic does not produce fidelity;

(2) Using the cord, insert, push rod, etc., the gap or special exhaust plug exhaust;

(3) Sometimes, in order to prevent the product from causing vacuum deformation when the article is taken, it is necessary to design air sales;

(4) Sometimes, in order to prevent the product from vacuum adsorption of the mold, the anti-vacuum adsorption element is designed.

8. Design of cooling system

The design of the cooling system is a cumbersome work, and it is necessary to consider the uniformity of cooling effects and cooling.

The impact of the cooling system on the overall structure of the mold. The cooling system design includes the following:

(1) The arrangement of the cooling system and the specific form of the cooling system;

(2) The specific location and size of the cooling system;

(3) Key parts such as moving model cores or insert cooling;

(4) Cooling of side sliders and side cores;

(5) The design of the cooling element and the selection of cooling standard components;

(6) Design of sealing structure.

9. Design of an overhead system

The top form of the article is summarized, which can be divided into mechanical top out, the hydraulic surgery, and the pneumatic top three categories.

The push rod is jealous in the machine, the push plate is jealous, the push plate is jealous, and the push block is out and the complex is over.

The top out of the product is the last link during the injection molding process. The quality of the top quality will finalize the quality of the product, because

Therefore, the top out of the article is not ignored. Comply with the following principles when designing the system

(1) In order to make the product do not cause deformation due to the top, the thrust point should be as close as possible to the core or difficult to demold.

The elongated hollow cylindrical columns are used. The arrangement of the thrust point should be as uniform as possible.

(2) The thrust point should act in the largest portion of the product, that is, the rigid parts, such as the wall of the rib, the ruthies, housing form, etc..

(3) Try to avoid the thrust point on the thin plane of the article, prevent the product crack, perforation, etc. Shell-shaped article

And the cylindrical product is multi-push plate

(4) In order to avoid the appearance of the article, the top out of the apparatus should be provided in the concealed surface or non-decorative surface of the article. Correct

In particular, the transparent article should pay particular attention to the selection of top-out positions and top out.

(5) In order to make the article are uniform at the time of top, it is often used to modify the article due to vacuum adsorption.

Composite or special form of top out system, such as push rod, push plate or push rod, push composite, or intake push

Top out of the bar, push block, etc., if necessary, the intake valve should be provided

10. Design of the guide

The guiding device on the plastic injection mold has been determined when adopting a standard model. Under normal circumstances, designers

Just select it according to the model specification. However, according to the requirements of the product, the precision guide is required, the designer must be

Specific design according to the mold structure.

Generally, the guide is divided into operation, the guide between the migration, the push plate and the push rod fixing plate, the push plate and the movable template

Guide, the guide, the gear plate and the throttle plate.

Generally, the guiding device is reduced due to the restriction of processing precision or for a period of time, and it will be directly shaded.

The accuracy of the sound product must also be designed to design a precise guiding positioning device for products with high precision requirements.

Precision positioning elements, some have been standardized, such as tapered positioning, positioning blocks, etc. can be used, but some precision orientation

The positioning device must be specifically designed according to the specific structure of the mold.

11. Determination of the model and the selection of standard parts

After all of the above is all determined, the design is designed according to the content design. When designing the model, choose the standard as much as possible

The model, determine the form, specifications, and standard code of the standard model.

Standard parts include two major categories: general standard parts and mold specializes. General standard parts such as fasteners, etc. Mold dedicated standard

Quasi-set, push, push rod, push, guide post, guide sleeve, mold special spring, cooling and heating element, secondary

Standard components such as classification mechanism and precision positioning.

It must be pointed out that the standard model and standard parts are as designed as much as possible because the standard parts have a large part.

It has been commercialized, ready to buy at the market, which is extremely advantageous to reduce manufacturing cycles and reduce manufacturing costs.

After the size of the model is determined, the necessary strength or rigid calculation is performed on the mold, and the selected model is

No appropriate, especially for large molds, this is especially important.

12. Selection of mold steel

The selection of the mold molded parts (cavity, core) material is mainly determined according to the mass of the product, the plastic category is determined.

At high gloss or transparent products, the 4Cr13-like martensite-resistant stainless steel or aging hardened steel is mainly used.

A glass-based plastic product containing glass fibers should be selected from the type of high-resistant resistance such as CR12MOV.

When the material of the article is a PVC, a POM or a flame retardant, it is necessary to use corrosion resistant stainless steel.

Products are general plastics, usually with pre-ferrous tuning steel, if the product is large, quenching back is used.

13. Draw an assembly diagram

After the module and the relevant content are determined, the assembly diagram can be drawn. During the drawing of the assembly, the selected cast

Systems, cooling systems, core mechanisms, top out systems, etc., have further coordination and improvement, and achieve a relatively perfect design.

14. Drawing of the main parts of the mold

When drawing the cavity or core diagram, you must pay attention to whether the given mold size, tolerance, and demolding slope are coordinated.

Whether the design benchmark is coordinated with the design benchmark of the article. At the same time, it is necessary to consider the process and use of the core during processing.

Mechanical performance and its reliability.

15. School of design drawings

After the mold is designed, the mold designer will design the design and the relevant original information and the calculation draft.

Conduct school pairs.

The proofreading personnel should have the overall structure, work of the mold for the design basis and customers provided by the customer.

Principle, the feasibility of operation, etc., the comparison system proofread.

16. Significance of design drawings

After the mold design drawings are completed, the customer must be given to the customer approval. Only after the customer agrees, the mold can prepare a projection

Enter the production. When a customer has a major opinion, it is necessary to pay the customer to be approved after redesign.

Satisfied.

Some of the above mold design procedures, some of which can be considering, some content must be considered repeatedly because

Some factors often contradict each other, must pass the continuous argument, mutual coordination in the design process, can be better

It is necessary to treat the content of the mold structure, must be taken seriously, often do a few options simultaneously,

The structure will list the advantages and disadvantages of all aspects, and then analyze and optimize. Because of the structural reasons,

Pick up the manufacture and use of the mold, even causing the entire mold. Therefore, the mold design is the key to ensuring the quality of the mold.

One step, its design process is a system engineering.