Die-casting process for controlling internal porosity by applying extrusion speed
By adjusting the extrusion start-up time, pressure, and speed, the problem of gas shrinkage cavities in the die casting process was solved, thus achieving improved internal quality and production stability for small and medium-sized die castings.
Patent Information
- Application Number
- CN202410989986.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-23
- Publication Date
- 2026-01-23
AI Technical Summary
Existing die casting processes are prone to producing shrinkage cavities in the thicker parts of small and medium-sized die castings, and it is difficult to match the process parameters of extrusion delay, pressure and core puller movement, resulting in substandard internal quality or unstable production.
By adjusting the extrusion start time, pressure, and speed, and by using slow extrusion and holding it for a certain period of time before withdrawing, the extrusion speed and pressure of the extrusion pin can be controlled to ensure the consistency of the aluminum liquid temperature and avoid the formation of gas shrinkage cavities.
It improves the internal quality of small and medium-sized die-cast parts, ensures the continuity and stability of production, and meets internal quality standards.
Smart Images
Figure CN121373353A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of die casting, and more specifically to a die casting process that uses extrusion speed to control internal porosity. Background Technology
[0002] Small and medium-sized die-cast parts are prone to shrinkage cavities in the thicker parts of the die-casting wall, especially in load-bearing parts such as casting assemblies where strength requirements are very high. The internal quality of this part of the casting is very important. Generally, the porosity of the internal cross-section is used as the standard for judging the internal quality.
[0003] Due to the limitations of die casting, extrusion processes are typically used to ensure the quality requirements of internal shrinkage cavities in the product. Conventional extrusion processes mainly involve two aspects: extrusion duration and extrusion pressure. During production, it is difficult to achieve perfectly matched process parameters for these two key technical conditions. This is mainly reflected in:
[0004] (1) As Figure 1 As shown, the extrusion delay is short and the extrusion is easy to complete, but the internal temperature of the casting is still scorching hot, and a new shrinkage porosity will be generated after the extrusion action is completed.
[0005] (2) Extrusion delay: How to ensure the extrusion stroke is in place and the internal quality meets the standard? However, sometimes the aluminum liquid outside the casting has solidified, and the core puller has too much resistance. After the core puller is started, the extrusion pin cannot move or the stroke is not in place, causing the extrusion action to fail and the internal quality of the casting to be substandard.
[0006] (3) Increasing the extrusion pressure can enhance the start-up and travel distance of the core puller, but it can easily cause deformation and breakage of the extrusion pin, which seriously affects the stability and continuity of die casting production. Summary of the Invention
[0007] To address the technical problems existing in the prior art, the present invention provides a die casting process that uses extrusion speed to control internal porosity.
[0008] To achieve the above objectives, the technical solution of the present invention is as follows:
[0009] A die-casting process that uses extrusion speed to control internal porosity includes the following steps:
[0010] Step 1: Adjust the delay setting for the extrusion start time;
[0011] Step 2: Adjust the extrusion pressure according to the area of the extrusion pin and the internal resistance of the casting;
[0012] Step 3: Start the die-casting device, adjust the extrusion speed, and slowly squeeze the extrusion pin into the casting;
[0013] Step four, the extrusion pin is extruded into the casting and kept for a certain time before being withdrawn, and spraying is carried out.
[0014] As a preferred technical solution, in step one, the extrusion starting time is delayed according to the casting temperature, and the delay time is 1.30-1.50 s.
[0015] As a preferred technical solution, the delay time of the extrusion starting is 1.40 s.
[0016] As a preferred technical solution, in step two, the extrusion pressure is 90-100 kgf.
[0017] As a preferred technical solution, the die casting device comprises a movable die, a fixed die, an extrusion pin, an extrusion pin connecting device and a hydraulic core-pulling device, the hydraulic core-pulling device is connected with the extrusion pin through the extrusion pin connecting device, the extrusion pin makes reciprocating motion in the die casting process, the fixed die is arranged outside the extrusion pin connecting device, and the movable die is arranged outside the casting and in contact with the fixed die.
[0018] As a preferred technical solution, in step three, the extrusion speed is 55-65% of the full speed.
[0019] As a preferred technical solution, the extrusion speed is 60% of the full speed.
[0020] As a preferred technical solution, in step four, the keeping time after extrusion is 2 s.
[0021] Compared with the prior art, the present application has the following beneficial effects:
[0022] The die casting process of the present application uses the extrusion speed to control the internal porosity, the extrusion time can be delayed, the aluminum liquid temperature acted on by the extrusion pin end face from the starting to the end of the stroke is kept consistent by controlling the extrusion speed parameter, the stability of the internal shrinkage hole is strengthened, and the phenomena of affecting the production continuity such as the extrusion stroke not being in place and the extrusion pin being deformed and broken in the die casting production process are avoided, so that the internal quality of the die casting is ensured to reach the corresponding technical standard. BRIEF DESCRIPTION OF DRAWINGS
[0023] Figure 1 is a casting state schematic diagram in normal operation of the prior art of the present application;
[0024] Figure 2 is a casting state schematic diagram when the die casting process of the present application using the extrusion speed to control the internal porosity is used;
[0025] Figure 3 is a technical parameter table of the die casting process of the present application using the extrusion speed to control the internal porosity;
[0026] Figure 4This is a schematic diagram of the operation of the die-casting process of the present invention, which uses extrusion speed to control internal porosity;
[0027] Figure 5 This is a comparison chart showing the finished product effects of castings produced using existing technology and those produced using the die casting process of this invention, which controls internal porosity through extrusion speed.
[0028] In the diagram: 1. Casting; 2. Moving mold; 3. Fixed mold; 4. Extrusion pin; 5. Extrusion pin connecting device; 6. Hydraulic core pulling device. Detailed Implementation
[0029] The technical solution of the present invention will be further described below with reference to specific embodiments:
[0030] like Figure 2 As shown, a die-casting process that uses extrusion speed to control internal porosity includes the following steps:
[0031] Step 1, as follows Figure 3 As shown, the extrusion start time is adjusted and controlled by delay according to the temperature of casting 1 (aluminum solidus line). The delay time is 1.30 to 1.50 s, preferably 1.40 s.
[0032] Step 2: Adjust the extrusion pressure according to the area of the extrusion pin 4 and the internal resistance of the casting 1. The extrusion pressure is 90-100 kgf, preferably 90 kgf.
[0033] Step 3, as Figure 4 As shown, the die-casting device is started. The die-casting device includes a moving mold 2, a fixed mold 3, an extrusion pin 4, an extrusion pin connecting device 5, and a hydraulic core-pulling device 6. The hydraulic core-pulling device 6 is connected to the extrusion pin 4 through the extrusion pin connecting device 5. The extrusion pin 4 reciprocates during the die-casting process. The fixed mold 3 is located outside the extrusion pin connecting device 5, and the moving mold 2 is located outside the casting 1 and is in contact with the fixed mold 3.
[0034] After extrusion starts, adjust the extrusion speed to 55-65% of the full speed according to the actual situation. Preferably, set the extrusion speed to 60% of the full speed and use the technical parameter setting of fast start and slow extrusion to keep the temperature of the aluminum liquid acting on the four end faces of the extrusion pin consistent from start to end of stroke, and enhance the stability of the internal gas shrinkage cavities.
[0035] Step 4: After the extrusion pin 4 is inserted into the casting 1, it is held for 2 seconds and then withdrawn at full speed. In this embodiment, the withdrawal pressure is 130 kgf. Then spraying is performed. The spraying entry time is 6.5 seconds and the spraying withdrawal time is 2.0 seconds.
[0036] like Figure 5As shown, the die casting process of the present application is suitable for locally extruding the effective volume of 9-16 cm3 of the casting 1, and the porosity of the produced casting 1 is only 2.65%, and the internal quality of the casting 1 can reach the corresponding technical standards.
[0037] The embodiment is only a further explanation of the present application, and is not a limitation of the present application, and those skilled in the art can make non-creative modifications to the embodiment according to the needs after reading the specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.
Claims
1. A die casting process for controlling internal porosity with extrusion speed, characterized by, The die casting process comprises the following steps: Step one, delay adjustment setting for extrusion starting time; Step two, adjusting extrusion pressure according to extrusion pin area and internal resistance of the casting; Step three, starting the die casting device, adjusting extrusion speed, and slowly extruding the extrusion pin into the casting; Step four, keeping for a certain time after the extrusion pin is extruded into the casting, and then withdrawing and spraying.
2. The process of die casting with internal porosity control using extrusion speed as claimed in claim 1, wherein, In the step one, the extrusion starting time is delayed for 1.30-1.50 s according to the temperature of the casting.
3. The process of die casting with internal porosity control using extrusion speed as claimed in claim 2, wherein, The delay time for the extrusion starting is 1.40 s.
4. The process of utilizing squeeze velocity to control internal porosity of die casting as claimed in claim 1, wherein, In the step two, the extrusion pressure is 90-100 kgf.
5. The process of employing extrusion speed to control internal porosity of die casting as claimed in claim 1, wherein, The die casting device comprises a movable die, a fixed die, an extrusion pin, an extrusion pin connecting device, and a hydraulic core-pulling device, the hydraulic core-pulling device is connected with the extrusion pin through the extrusion pin connecting device, the extrusion pin makes reciprocating motion during the die casting process, the fixed die is arranged outside the extrusion pin connecting device, and the movable die is arranged outside the casting and in contact with the fixed die.
6. The process of employing extrusion speed to control internal porosity of die casting as claimed in claim 1, wherein, In the step three, the extrusion speed is 55-65% of the full speed.
7. The process of die casting with internal porosity control using extrusion speed as claimed in claim 6, wherein, The extrusion speed is 60% of the full speed.
8. The process of employing extrusion speed to control internal porosity of die casting as claimed in claim 1, wherein, In the step four, the keeping time after the extrusion is 2 s.