Aluminum die casting mold structure

I. Die casting mold foundation

1. Die casting concept

Die casting:It refers to the molding process in which high-temperature molten metal liquid fills the cavity quickly under high speed and high pressure under certain conditions and cools rapidly under certain pressure.

Die casting mold is an important process equipment in die casting production, it is extremely important to the production can be carried out smoothly, the quality of casting plays an extremely important role, it and die casting production process, production operation exists and mutual influence and mutual constraints, close relationship.

Die casting die determines the casting shape and size tolerance level; its pouring system determines the filling condition of the molten metal; the production process, control and regulation of the die casting process heat balance; the strength of the mold limits the maximum limit of the ejection ratio pressure, which affects the productivity of die casting production.

2. Structure of die-casting mold

Die casting mold is mainly composed of two parts: the fixed mold and the moving mold, in order to ensure the movement of the mold and the smooth withdrawal of the workpiece, with a set of complex systems and structures, common structures are: the fixed mold, the moving mold, the core pulling mechanism, tilt pins, guide slide groove, the slider, the limit blocks, springs, screws, nuts, wedge tight blocks, hydraulic core pulling mechanism, the moving mold set plate, the core, the fixed mold plate, the guide pillar and guide bushings, the push plate, the fixed plate, the diversion cone, pads, and so on. Cones, pads, etc.

Below is an exploded view of one of the more common die casting mold structures.

1) Fixed mold

Fixed mold is the main component of die casting mold, fixed mold and die casting machine injection part connected, and fixed in the pressure machine injection part and pouring system is connected, is an important part of the die casting cavity. Mainly by the fixed mold block, fixed mold plate, guide pillar, chisel block, oblique guide pillar, gate set, fixed mold core drawing mechanism and other parts.

2) Dynamic mold

The moving die is another important part of die casting mold, the moving die is and the fixed die to form the die casting mold forming part of another whole, it is generally fixed in the die casting machine on the middle plate, with the middle plate for the merging movement, and the fixed die part of the separation of the close. Generally the core pulling mechanism and ejector mechanism are mostly in this part.

3) Core extraction mechanism

It is a movable core mechanism that extracts molded parts with inconsistent movement in the direction of mold opening. The core-extraction mechanism mainly consists of the following parts: slanting guide pillar, side cores, slider, guide slide, limit blocks, screws, springs, nuts, screws, etc. The following figure shows the core-extraction mechanism. As shown in the figure below.

4) Skew pin

Function: In the process of mold opening, force the slide to move and extract the core.

There are two kinds of core pulling and outer core pulling, and its cross-section shape mostly adopts flat circle to prevent pulling the core from straining the slider, and according to the different structure of the mold, there is a delayed core pulling.

The size of the bevel α is related to the amount of core pulling force, the length of the core stroke, and the amount of bending force applied. The value of the bevel angle α is generally 10°, 15°, 18°, 20°, 25°. The diameter of the skew pin depends on the size of the core packing force.

Skew pin length = fixed part + working section size + (5~10) cm

Material: T8A, T10A; Heat treatment: HRC (50~55)

5) Guide Slide

Role: Components that define the trajectory of the slider.
Material: T8A, T10A, 40cr    
Heat treatment: HRC 42~47

6) Slider

Function: A component that connects the core to the taper pin for the core pulling motion, and the taper pin to complete the core pulling action together.

Parameters: Height B and width C of the slide are determined by the core dimensions.

The length of the slider A is related to B, C. For the slider to work stability is required.

                 A ≥ 0.7C A ≥ B

Material: T8A, T10A, H13

Heat treatment: HRC 42~47

7) Limit block

Role: after the slider is withdrawn, it is required to keep it firmly in a certain position, so as to facilitate the closing of the mold again when the diagonal pin is accurately inserted into the slider diagonal hole, so that the slider is accurately reset.

Total dialing distance = core distance + safety value

8) Spring, screw, nut

The slider moves and then relies on spring tension to keep the slider tight against the side of the limit block.

Main parameters: spring tension > body weight of the slider, ensuring accurate positioning of the slider.

9) Hydraulic core pulling mechanism

Mainly consists of hydraulic cylinder stroke control switch, side core, hydraulic core extractor and other parts.

10) Movable Mold Sleeve

Role: play a fixed support fixed mold insert role, fixed mold set plate by tensile, bending, compression of three kinds of stress. Therefore, the size of this plate and mold quality, rigidity and close relationship, should pay full attention.

Material: 45#, A3.

11) Core 

Function: Used to form holes or recesses in the direction of mold opening or not in the direction of mold opening, the shape and size according to the requirements of the product.

Material: H13, 3Cr2w8v

Heat treatment: HRC43~47

12) Fixed mold seat plate

Role: one end face is fastened in the die-casting machine head plate, so that the mold compression positioning, the other end face and the mold body combined to withstand the machine pressure, the two end faces require sufficient pressure area pressure casting machine nozzle and pressure chamber mounting holes required to be matched and accurate.

Material: 45# , A3

13) Fixed mold inserts, moving mold inserts, cores

This is the size of the molding die casting parts, the cavity size is determined by the casting size + corresponding casting shrinkage, various alloy shrinkage were AL: 0.3 ~ ~ 0.7, Zn: 0.3 ~ 0.6, Mg: 0.4 ~ 0.8, Cu: 0.5 ~ 1.0 (%)

Determination of the wall thickness size of the insert: according to the shape and size of the casting to determine the size.

Material: H13, 4Cr5MoV1Si, 3Cr2W8V, 8407, SKD61         

Heat treatment: HRC43~47

14）Gate sleeve, cooling water sleeve

Function: The gate sleeve constitutes a straight pouring channel, ensures the smooth movement of the injection punch, and ensures the smooth pressure transfer and filling of the liquid metal. The diameter of the gate sleeve is selected according to the required specific pressure of the casting and the weight of the casting. Requirements for the inner surface of the high surface brightness. For cold room die casting machine mold production precision for higher, affecting the life of the hammer head.

Material of gate sleeve: H13,, 3Cr2W8V

Cooling water jacket material: 45 #           

Heat treatment : HRC43~47

15) Guide pillar and guide bush

Role: to play a guiding role, to ensure that the dynamic, fixed mold in the installation and the correct position of the mold, the guide pillar and guide sleeve should be sufficient rigidity and wear resistance, the requirements of reasonable clearance, the mold should be opened when the larger oil tank, to prevent cold welding.

Guide pillar diameter: D = K√F . (F: mold parting surface area K: coefficient 0.07 ~ 0.09)

Height of guide pillar: In order to ensure the safety when closing the mold, the height of the guide pillar should be greater than the highest core height.     

Material: T8A          

Heat treatment: HRC50～55

16) Putter

Function: To eject the casting in conjunction with other ejector components. The arrangement of ejector should equalize the ejector pressure on each part of the casting, and there are different types of ejector according to the shape of the casting and different requirements. Control the number of ejector pins.

Material: H13, SKD61

17) Push plate, fixed plate

Push plate: push plate bear die casting machine ejector rod force, along the guide column movement. Should have a certain strength.   

Fixed plate: Fixed top bar reset lever and other parts along the guide column movement, top bar table countersunk hole height

Material: 45#

18) Legs

The end face is fastened to the wall plate of the die casting machine, and the other end is combined with the mold body to bear the clamping force of the machine, and to bear the ejection reaction force when ejecting the casting. Fastening form must be reliable, its height size to meet the completion of the ejection casting action. Adjust the thickness of the mold.

Material: 45#

19) Diversion cone

Adjust the cross-sectional area of the straight sprue to change the flow direction of the metal liquid and reduce the consumption of metal liquid. Cooling system is provided inside.

Material: H13, SKD61

Heat treatment: HRC43~47

20) Padding

It plays a supporting role for the mold, improves the rigidity of the rear mold, and reduces the instantaneous deformation of the mold induced by the shock wave of the machine during production. The production material is ordinary cast iron or 45# steel. Position and size control is the key.

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