1 review the product plan and 3D drawing, and analyze the process of parts
The alloy material, shape and structure, dimensional accuracy and other characteristics of product parts should be examined and analyzed from the perspective of die casting technology. For those factors that are not suitable for die casting, it is necessary to negotiate with users to rationalize them. Special mold structure and special process measures should be adopted only when necessary. For example, the movable insert forming the inner concave and the vacuum die casting system are used. For the process analysis of the part drawing, the general problems to be noticed are listed as follows:
(1) Whether the structure shown on the plan and the 3D drawing is consistent; whether the dimensions on the plan are marked completely; whether the dimensions marked are the same as those measured on the 3D drawing; whether the dimensions noted on the plan icon take into account the fillet transition and the size end produced by the die inclination.
(2) Type of alloy and required technical properties (considering mechanical properties, corrosion resistance, casting properties, processing properties, etc.).
(3) Dimensional accuracy and shape and position accuracy. According to the dimensional accuracy, we can decide whether to die-casting or what kind of post-processing technology to use.
(4) Wall thickness, wall connections, ribs and fillets.
(5) Parting, die direction and die inclination.
(6) The core pulling position, whether there is cross of core and concave inside.
(7) Push out direction, push rod position.
(8) Die casting of holes, deep holes, threads and teeth.
(9) Clamping and positioning of the casting insert and metal cladding.
(10) Patterns, characters, symbols and embossing.
(11) Datum and machined parts.
(12) Surface appearance.
2. Preliminary analysis of die structure
(1) Select the parting surface, determine the number of cavities (modulus), calculate the die casting projection area according to the projection area of the part contour on the parting plus the area of the pouring overflow system, and then calculate the die locking force.
(2) Select the location of the inner gate entrance and determine the general layout of the gating system.
(3) Determine the core pulling position and select a reasonable core pulling scheme.
(4) Determine the position of the push out element and choose a reasonable push out and reset scheme.
(5) For castings with inserts, the way of mounting and fixing the inserts should be analyzed.
3 selection of die casting machine
After selecting the type of die-casting machine according to the alloy type, the die-casting machine shall be selected according to the projection area and quality requirements, and the balance of production load of existing equipment shall be taken into account.
(1) Determine the injection specific pressure, calculate the clamping force, estimate the die size, and select the model and specification of the die casting machine.
(2) Estimate the opening stroke and pushing force needed by the mold, whether the pushing return and hydraulic core pulling are needed.
(3) Select the accessories that the die casting machine needs to be equipped with, such as hydraulic core pulling device, applicable mold base, vacuum die casting system, etc.
2.4 rough drawing
After various process parameters are determined and confirmed, the die casting blank drawing is the main basis for detailed mold design and fixture design; the basis for judging the quality of the casting blank; the basis for the buyer to recheck and inspect the quality approval; the basis for the subsequent processes such as machining, injection molding, gluing, surface treatment, cold forming and other process equipment; die casting and post-processing cost accounting Basis.
The main contents to be expressed in drawing the rough drawing are as follows:
(1) Shape, dimension and accuracy of die casting.
(2) The surface with machining allowance shall be indicated with special symbols on the machining drawing.
(3) During machining, the position of the blank reference surface and the measurement reference surface can be indicated with specific symbols.
(4) The drawing number of the inlay and the location and size of the inlay.
(5) The position of the main parting surface, the position of the sliding block, the position of the front and rear die collision, the opening direction of the moving die and the fixed die shall be marked with special symbols.
(6) Position coordinate of push rod and its top dimension, positioning dimension of thimble and diameter of thimble.
(7) The location and size of the remaining gate and overflow channel residual root.
(8) Additional shape and size of die casting process (such as rib, boss, aisle, allowance, etc.).
(9) Shape, size and position of pattern, text, manufacturing mark, manufacturer code, production date, etc. on die casting.
(10) The value and value direction of die inclination are not indicated (increase the die angle by adding or subtracting materials).
(11) Is the value indicating the fillet radius.
(12) Dimensional tolerance grade is not noted.
(13) Acceptance standards of die casting (including the height of residual material level of thimble printing, waste level of water outlet, allowable height of batch front, allowable standard of defects such as surface shrinkage, chipping, air hole, shrinkage hole, surface roughness requirements of non machined surface, etc.)
(14) Die casting parts need special inspection, such as mechanical properties, air tightness test, etc.
(15) Alloy type designation and its technical standard code.
(16) Die casting blank weight or control weight.
(17) The part drawing number and name of the product.
(18) Customer name or code.
2. Basic requirements for design of die casting mold
(1) The die-casting parts produced shall conform to the shape, size and technical requirements specified on the die-casting blank drawing, especially try to ensure that the high-precision and high-quality parts meet the requirements.
(2) The die should be suitable for the requirements of die casting process, and the technical economy is reasonable.
(3) On the premise of ensuring the quality and safety of die-casting, reasonable, advanced and simple structure shall be adopted to ensure the accurate and reliable action, good rigidity of components, convenient disassembly and replacement of vulnerable parts, and to extend the working life of die-casting.
(4) All parts on the mould shall meet the requirements of machining process and heat treatment process. Proper material selection, matching accuracy selection
