Detailed introduction of die casting machine knowledge:
1. Composition and properties of commonly used die-casting alloys
The components of die-casting alloy are non-ferrous metals and ferrous metals. The non-ferrous metal alloys widely used in color are classified as follows:
Low melting point alloy, lead alloy, tin alloy, zinc alloy
Non-ferrous metal alloys, aluminum alloys
Refractory alloys, magnesium alloys, copper alloys
2. Processability of die casting structure
1. Wall thickness
<1> The minimum wall thickness and normal wall thickness of die castings are usually based on the area of the casting.
<2> In order to ensure good forming conditions for castings. The outer edge of the caster should maintain a certain wall thickness.
〈3〉 When there are inserts on the casting, the metal layer around the inserts should be thickened. In order to improve the packing tightness with the insert. The thickness of the metal layer is directly selected according to the insert.
2. Casting hole
Die-casting can inject relatively small holes, the relationship between the source of the hole and the hole
3. Casting fillet radius and draft angle
The casting fillet diameter is related to the wall thickness
4. Screw suction
0, 2-0, 3 mm plus allowance is required for die-casting external screw suction. The internal screw suction is generally die-casting out of the bottom hole, and then machine-added internal screw suction. The inner screw can also be directly die-casted.
5. Convex suction, direct suction and net suction
(1) Convex suction and straight suction must be drawn in the direction of the post mold only.
(2) Net suction is mainly used to reduce or eliminate defects such as flow marks or patterns on the surface of large flat die castings. The shape of the net should be conducive to mold manufacturing and demolding.
6. Text and logo
The size of the text is generally not less than the No. 5 font specified in GB126-74, the protruding height of the text is greater than 0.3mm, generally 0.5mm, the minimum line width is generally 1.5 times the protrusion height, taking 0.8, the minimum line spacing is greater than 0.3mm, and the mold is ejected The slope is 10-15 degrees, and sharp angles should be avoided at the end of the line.
7. Casting accuracy and machining allowance
(1) For the dimensional accuracy of parts that can be late, see the matching dimensional accuracy.
(2) A smaller value should be selected for the machining of die castings.
3. Die-casting equipment
1. Types and technical parameters of die-casting machine
2. Selection of die-casting machine
〈１〉 Clamping force
〈2〉 When pressure capacity
The capacity of the die casting machine is greater than the total amount of molten metal poured for the first time
G pressure treasure> (V1 V2 V3)r /1000 (kg)
G pressure treasure——compressor set pressure treasure capacity, KG
V1——The volume of die casting, CM3
V2——The total volume of the pouring system, CM3
V3——The volume of remaining material, CM3
R-alloy specific gravity, G/CM3, zinc alloy 6.3-6.7, aluminum alloy 2.6-2.7, alloy alloy 1.7-1.8, copper alloy 8.3-8.5
(3) Opening force and pushing force
It is estimated that the mold opening force and pushing force should be less than the maximum mold opening force and pushing force of the head selection die casting machine.
(4) Die size
a. The installation size of the mold should be compatible with the size of the template
b. After the full mold of the die-casting machine, the mold surface should be tightly tightened, and the total thickness of the mold after closing the mold is greater than the minimum clamping distance of the die-casting machine (usually 2000).
c. After the die-casting machine opens the mold, the casting can be taken out smoothly. After the maximum mold opening distance of the die-casting machine is subtracted from the total thickness of the mold, there should be a distance to take out the part (including pouring).
four. Typical structure of die casting mold
(1) The basic form of the phantom is composed of it
Basic form
(1) No-through hole mold body
(2) The role of the phantom structure
(2) Key points of mold design
(3) Arrangement of the inlay in the heavy board
