Introduction to knowledge and skills of mold design

Introduction to knowledge and skills of mold design

Mold design refers to employees engaged in digital mold design in enterprises, including cavity molds and cold molds. On the basis of traditional mold design, they make full use of digital design tools to improve mold design quality and shorten mold design cycle. Below, I have arranged some introductions about mold design for you. Welcome to reading.

Design technology of continuous stamping die (first lecture)

I. Preface:

According to the structure, stamping dies can be divided into three categories: simplex dies, compound dies and continuous dies. The first two kinds need more manpower and are not economical. Continuous dies can be produced in large quantities with high efficiency. Similarly, to design a set of high-speed precision continuous stamping die, it is also necessary to analyze the products you produce (including all products processed by stamping, Foxconn Group mainly includes terminals, computer cases, hardware used in connectors, and now mobile phone parts, etc. ). When designing the continuous die, we should pay attention to the module spacing, parts processing accuracy, assembly accuracy, matching accuracy and interference, so as to achieve the purpose of automatic batch production of continuous die.

2. The concept of unit design:

The overall structure of the stamping die can be divided into two parts: (1), * * * to part (2), and the parts that change according to different products. * * * General parts can be standardized or standardized, and parts that vary from product to product are difficult to standardize.

3. The composition and specifications of the template:

1. Composition of the template

The structure of stamping die can be divided into two categories according to the type, structure and difference of die: forward configuration structure and reverse configuration structure. The former is the most commonly used structure, while the latter is mainly used for drawing dies or special dies.

The main work includes:

(1) digital mapping? Convert three-dimensional product and mold models into two-dimensional engineering drawings used in conventional machining;

(2) Digital mold design? According to the product model and design intention, the related three-dimensional solid model of the mold is established;

(3) Digital analysis and simulation of mould? According to the product forming process conditions, structural analysis, thermal analysis, fatigue analysis and die movement analysis are carried out for the die parts.

(4) product forming process simulation? Injection molding and stamping;

(5) Customize the standard parts and standard design process suitable for the company's mold design;

(6) Mold production management.

2. Mold specifications

(1). Die dimensions and locking screws

The size of the template should be larger than the working area, and the standard template size should be selected. The position of the template locking screw is related to the mold type and template size. Among them, locking screws are most commonly used in the four corners of a single engineering mold, and the most standard working areas can be widely used. Long dies and continuous dies are most often arranged at the corners and middle positions and fixed with locking screws.

(2) Template thickness

The selection of template thickness is closely related to the structure of the die, the type of stamping process, the working force of stamping process and the precision of stamping process. It is difficult to determine the thickness of the die according to theoretical calculation. It is generally obtained by experience. The template thickness used in the design should be as small as possible, and standardized with the mold height and clamping height to facilitate procurement and inventory management.

4. Template design:

The main templates of continuous die include punch fixing plate, pressing plate and mother template. According to the precision of stamping products, the production quantity, the processing equipment and methods of the die and the maintenance mode of the die, the structural design has the following three forms: (1) block type, (2) yoke type and (3) insert type.

1. Integral type

Integral formwork, also known as integral structure, must be closed when processing and forming. Integral formwork is mainly used for molds with simple structure or low precision, and its processing mode is mainly cutting (no heat treatment is needed). After heat treatment, the template must be processed by wire cutting or electric discharge and ground again. When the template size is long (continuous die), two or more pieces will be used for one main body.

2. Yoke type

The central part of the yoke template is machined into a groove shape to assemble the block. Its structure depends on the application requirements, and the groove part can be composed of other templates. The advantages of this yoke template structure are: the groove is easy to machine, the width of the groove is adjustable and the machining accuracy is good. But low rigidity is its disadvantage.

Matters needing attention in the design of yoke formwork are as follows:

(1). The fit between the yoke plate structure and the stopper parts is medium fit or light fit. If a forced fit is adopted, the yoke plate will be replaced.

(2) The yoke plate also has the function of supporting the block, and it must have enough rigidity to bear the lateral pressure and surface pressure of the block. In addition, in order to closely combine the groove of the yoke plate with the block member, the corners of the groove member are machined to avoid. If the corner of the groove part of the yoke plate cannot be machined to be detached, the block part must be machined to be detached.

(3) At the same time, considering the internal shape of the block parts, the datum plane must be defined. In order to avoid deformation during stamping, we should also pay attention to the shape of each part.

(4) When the yoke plate is assembled by many pieces, the pitch will change due to the accumulated error in the processing of each piece. The solution is to design the middle block part in an adjustable way.

(5) Block parts adopt side-by-side combined die structure, because block parts will bear lateral pressure in the stamping process, resulting in gaps between block parts or inclined block parts. This phenomenon is an important reason for poor stamping, such as poor stamping size and chip blockage, so adequate countermeasures must be taken.

(6) According to its size and shape, the stopper parts in the yoke plate can be fixed in five ways: a. with locking screws, b. with keys, and c. with? D, fixing with the shoulder, and e, pressing the pressing piece (such as the guide plate) and fixing.

3. Mosaic

A circular or square concave part is processed in the template, and a block part is embedded in the template. This template is called embedded structure, which has the advantages of small cumulative tolerance, high rigidity, good reproducibility of decomposition and assembly accuracy. Embedded template structure has become the mainstream of precision stamping die because of its advantages of easy machining, machining accuracy determined by machining machine tools and few final adjustment items, but its disadvantage is that it needs high-precision hole machining machine tools.

When the continuous stamping die adopts this template structure, the empty station is designed to make the template have higher rigidity requirements. Precautions for embedded formwork structure are as follows:

(1). Machining of embedded hole: use vertical milling machine (or coordinate milling machine), comprehensive processing machine, coordinate boring machine, coordinate grinding machine, wire cutting machine and EDM machine to embed the template into the hole. When using WEDM, in order to improve the machining accuracy, the machining datum embedded in the hole should be machined by WEDM for two or more times.

(2) Fixing method of embedded parts: The determining factors of fixing method of embedded parts include machining accuracy, difficulty of assembly and disassembly, possibility of adjustment, etc. There are four fixing methods for embedded parts: a. fixing with screws, b. fixing with shoulders, c. fixing with toe blocks, and d. pressing the upper part with plates. Press fit is also used to fix the insert of the main template. At this time, the relaxation result caused by thermal expansion should be avoided, and the anti-rotation method should be designed when machining irregular holes with circular die sleeve inserts.