Extrusion casting pressure chamber melt purification device and extrusion casting method

Abstract

The extrusion casting pressure chamber melt purification device is used for being placed at a material receiving opening of a pressure chamber barrel so that melt can fall into the pressure chamber barrel after being shunted, and comprises a filter screen, a filter screen, a flow guide plate, a flow guide plate and a flow guide plate, the lower fixing piece comprises a main body part for supporting the filter screen, and the main body part is used for being matched with a material receiving opening of the pressure chamber cylinder; the upper fixing piece is matched with the lower fixing piece to clamp and fix the filter screen; and the moving part is connected with the lower fixing part and used for taking and placing the filter screen on the pressure chamber cylinder. The extrusion casting method comprises the steps that the pressure chamber barrel is poured out to prepare for material receiving, the extrusion casting pressure chamber melt purification device is placed at the position of a material receiving opening of the pressure chamber barrel, then melt is poured into the pressure chamber barrel, and after the extrusion casting pressure chamber melt purification device is taken away, the pressure chamber barrel is aligned for mold filling. According to the method, the melt in the pressure chamber is purified, the defects of an oxidation film and slag inclusion of the melt in the pressure chamber are overcome and removed, and the method has important significance in improving the mechanical property stability and the yield of extrusion casting parts.

Description

Technical Field

[0001] The invention belongs to the technical field of extrusion casting, and in particular relates to an extrusion casting pressure chamber melt purification device and an extrusion casting method. Background Art

[0002] Squeeze casting is a casting method that transfers the refined and purified molten melt into a pressure chamber, and under the push of the punch, the melt is steadily filled into the mold cavity at a low speed, and then solidified under pressure. In recent years, with the rapid rise and development of my country's new energy vehicle industry, more and more high-strength and high-service aluminum alloy chassis parts, such as steering knuckles, control arms, shock towers, brackets, support arm products, and even integrated subframes, are squeezed. Products such as runner plates and battery end plates in the thermal management system of new energy vehicles are also squeezed.

[0003] Squeeze casting equipment generally adopts the method of pouring out the pressure chamber to receive the material, returning it to the vertical direction, and docking it with the mold for injection. During extrusion casting, the material spoon, driven by the mechanical arm, takes the melt from the furnace beside the machine, moves the material spoon to the top of the pressure chamber, tilts the material spoon to pour the melt into the pressure chamber, and after the pressure chamber returns to the center, it docks vertically with the mold, and the filling head pushes the melt into the mold cavity to complete the filling and solidification molding process under pressure. However, in the process of pouring out the pressure chamber barrel to receive the material, it is easy to cause oxidation of the melt, which ultimately leads to a high content of oxide film in the casting, substandard mechanical properties, and unqualified products.

[0004] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0005] The object of the present invention is to provide an extrusion casting pressure chamber melt purification device and an extrusion casting method, which can reduce the oxide film defects inside the casting and ensure that the casting has higher mechanical property stability and yield rate.

[0006] In order to achieve the above object, a technical solution provided by a specific embodiment of the present invention is as follows:

[0007] A squeeze casting pressure chamber melt purification device is used to be placed at the material receiving port of the pressure chamber cylinder so that the melt is diverted and then falls into the pressure chamber cylinder, and at least comprises:

[0008] Filter;

[0009] The lower fixing member includes a main body portion supporting the filter screen, wherein the main body portion is used to cooperate with the material receiving port of the pressure chamber cylinder;

[0010] The upper fixing piece cooperates with the lower fixing piece to clamp and fix the filter screen;

[0011] The movable part is connected with the lower fixed part and is used for taking and placing the filter screen on the pressure chamber cylinder.

[0012] In one or more embodiments of the present invention, the middle portion of the filter screen is recessed downward to form a chamber, and the depth of the recess is 30 to 50 mm.

[0013] In one or more embodiments of the present invention, the filter mesh number is 10 to 20 meshes.

[0014] In one or more embodiments of the present invention, a first pressing portion is provided on the main body, and a second pressing portion cooperating with the first pressing portion is provided on the upper fixing member.

[0015] In one or more embodiments of the present invention, a locking member for locking the upper fixing member and the lower fixing member is further included.

[0016] In one or more embodiments of the present invention, the main body is provided with a guide portion for cooperating with the material receiving port of the pressure chamber tube.

[0017] In one or more embodiments of the present invention, the lower fixing member is in the shape of a ring or a hollow polygon.

[0018] In one or more embodiments of the present invention, the upper fixing member is in the shape of a ring or a hollow polygon.

[0019] Another specific embodiment of the present invention provides a technical solution as follows:

[0020] An extrusion casting method at least includes: the pressure chamber cylinder is tilted out to prepare for receiving materials, the above-mentioned extrusion casting pressure chamber melt purification device is first placed at the material receiving port of the pressure chamber cylinder, and then the melt is poured into the pressure chamber cylinder through a filter screen. After the extrusion casting pressure chamber melt purification device is removed, the pressure chamber cylinder is returned to the normal position for filling.

[0021] In one or more embodiments of the present invention, after the squeeze casting pressure chamber melt purification device is removed, a new filter screen is replaced before the next casting process is carried out.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. The use of the squeeze casting pressure chamber melt purification device can greatly reduce the number of oxide film and slag inclusion defects in the melt in the pressure chamber, purify the melt in the pressure chamber, and greatly reduce the oxide film and slag inclusion defects in the squeeze casting, improve the stability of the overall mechanical properties of the casting, improve the casting production yield, and ensure that the casting can meet the service requirements;

[0024] 2. The extrusion casting method of the present invention has extremely high flexibility and adaptability, does not involve high-cost modification of the extrusion casting equipment and platform, will not change the existing production line layout, and will not be restricted by the existing production line layout. According to the actual situation, manual placement of the extrusion casting pressure chamber melt purification device can be selected, or a mechanical arm can be added to realize automated operation;

[0025] 3. The modification cost of the extrusion casting method in the present invention is low, and only involves the addition of a melt purification device in the extrusion casting pressure chamber and the cost of an additional filter for each casting. If the modification of automated equipment is considered, it only involves the increase in the cost of the linkage structure of the robotic arm and the supporting point trigger signal, which is cost-effective. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 It is a schematic structural diagram of a melt purification device for a squeeze casting pressure chamber in Example 1 of the present invention;

[0028] Figure 2 It is a working schematic diagram of the melt purification device for the squeeze casting pressure chamber in Example 2 of the present invention;

[0029] Figure 3 is an operation diagram of the squeeze casting method in Example 2 of the present invention;

[0030] Figure 4 This is a macroscopic fracture diagram of the casting in Example 2 of the present invention;

[0031] Figure 5 This is a SEM photo of the fracture of the casting in Example 2 of the present invention;

[0032] Figure 6 is the stress-strain curve of the casting in Example 2 of the present invention;

[0033] Figure 7 This is an operation diagram of the squeeze casting method in Comparative Example 1 of the present invention;

[0034] Figure 8 This is a macroscopic fracture diagram of the casting in Comparative Example 1 of the present invention;

[0035] Fig. 9 This is a SEM photo of the fracture of the casting in Comparative Example 1 of the present invention;

[0036] Fig.10is the stress-strain curve of the casting in Comparative Example 1 of the present invention;

[0037] Fig.11 Comparison of stress-strain curves of the castings in Example 2 of the present invention and Comparative Example 1.

[0038] Description of main reference numerals:

[0039] 1. Filter screen; 11. Filter part; 12. Mounting part; 2. Lower fixing part; 20. Main body; 21. Step; 22. Raised ridge; 23. Handle; 3. Upper fixing part; 4. Dovetail clamp; 5. Pressure chamber cylinder; 6. Punch; 7. Injection connecting rod; 8. Material spoon. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0041] During extrusion casting, when the spoon takes the melt from the machine-side furnace, such as aluminum alloy, magnesium alloy, etc., a layer of oxide film covers the melt on the surface of the machine-side furnace. After the spoon pours the material, the residual oxide film in the spoon has not been blown away, etc., which will enter the spoon during the material filling process. At the same time, the refining agent and other slag inclusion defects remaining in the melt in the machine-side furnace may also be taken into the spoon. When the spoon pours the melt into the pressure chamber, this part of the primary oxide film and the slag inclusion defects in the machine-side furnace are all transferred to the pressure chamber.

[0042] In addition, when the scoop pours the melt into the pressure chamber, the melt impacts the chamber wall quickly and turbulently, causing the melt to flip and entrain gas, oxidize and slag at the bottom of the pressure chamber, forming a secondary oxide film, and finally forming a dense and wrinkled oxide film layer of a certain thickness on the surface of the pressure chamber. Eventually, these oxide films and slag inclusion defects enter the casting, pouring system and overflow system. A large number of oxide films and slag inclusion defects seriously affect the stability of the mechanical properties of the extrusion castings and cannot meet the service requirements of extrusion casting parts.

[0043] To this end, the present invention provides an extrusion casting pressure chamber melt purification device, which can improve the problem of oxide film defects in the pressure chamber caused by the melt transfer process of the extrusion casting complete set of equipment, and can effectively improve the mechanical property stability of the extrusion casting parts and the yield rate of the extrusion casting parts.

[0044] A specific embodiment of the present invention provides an extrusion casting pressure chamber melt purification device, including a filter screen, a lower fixing part and an upper fixing part. The filter screen is clamped and fixed by the lower fixing part and the upper fixing part to place the filter screen at the material receiving port of the pressure chamber cylinder, so that the melt is diverted and falls into the pressure chamber cylinder when pouring the material.

[0045] Specifically, if the melt falls into the pressure chamber cylinder too fast, it is very easy for the melt to turn over and entrain gas, oxidize and slag to form a secondary oxide film. Placing a filter at the material receiving port of the pressure chamber cylinder can not only filter out the primary oxide film and slag inclusions such as refining agents that already exist in the melt, but more importantly, when the melt passes through the mesh of the filter, the melt is divided into fine liquid flows, and the fast, turbulent impact movement form is changed, thereby effectively solving the problem of turbulent melt entrainment and forming a secondary oxide film, ultimately reducing the oxide film and slag inclusion defects in the casting and ensuring the quality of the casting.

[0046] Furthermore, the lower fixing member includes a main body, which is annular or hollow polygonal. Specifically, the main body can be a hollow quadrilateral, pentagon or hexagon. The upper fixing member is annular or hollow polygonal. Preferably, the shape of the upper fixing member is the same as that of the lower fixing member to better clamp the filter screen. The main body is provided with a guide portion for cooperating with the material receiving port of the pressure chamber tube. The guide portion is specifically a step. When the lower fixing member is placed at the material receiving port of the pressure chamber tube, the step plays a guiding role. When the main body is annular, the step is arranged along the periphery of the main body. Preferably, the outer diameter of the step is slightly smaller than the inner diameter of the top end of the pressure chamber tube.

[0047] Furthermore, a first pressing part is provided on the main body, and a second pressing part cooperating with the first pressing part is provided on the upper fixing part. The first pressing part can be a convex ridge or a pressing groove provided on the main body, and correspondingly, the second pressing part is a pressing groove or a convex ridge. The cooperation of the convex ridge and the pressing groove can make the lower fixing part and the upper fixing part accurately align and press the filter screen. Of course, the lower fixing part and the upper fixing part can also be fixed by magnetic attraction, such as the first pressing part and the second pressing part are both magnetic attraction parts, and the filter screen is made of iron.

[0048] Furthermore, a locking member for locking the upper fixing member and the lower fixing member is also included. The locking member is used to further lock the upper fixing member and the lower fixing member to prevent the filter screen from being rushed into the pressure chamber during the turbulent melt transfer process, causing abnormal squeeze casting production. The locking member can be a dovetail clamp or a bolt and nut. When it is a bolt and nut, the upper fixing member and the lower fixing member are correspondingly provided with mounting holes.

[0049] Furthermore, a moving part is connected to the lower fixed part, which is used to move the squeeze casting pressure chamber melt purification device to the upper end surface of the pressure chamber cylinder and cooperate with it before the material spoon pours the melt into the pressure chamber cylinder, and to move the squeeze casting pressure chamber melt purification device out after the material spoon finishes pouring the melt into the pressure chamber cylinder. The moving part is specifically a handle, and during operation, the lower fixed part is moved manually, or the moving part is set as a component that cooperates with a mechanical arm, and the lower fixed part is moved by the mechanical arm, thereby moving the filter screen.

[0050] Furthermore, the middle part of the filter is recessed downward to form a chamber to accommodate and filter the melt. The cross-section of the filter is U-shaped. The mesh number of the filter can be selected according to actual needs. Preferably, the mesh number of the filter is 10 to 20, and the depth H of the filter is 30 to 50 mm.

[0051] Specifically, the appropriate number of filter meshes can, on the one hand, effectively filter the primary oxide film and slag inclusions such as refining agent in the melt in the material spoon to the outside of the pressure chamber; on the other hand, it can fully improve the rapid and turbulent impact movement of the melt during the pouring process, so that the melt can drip into the pressure chamber in the form of a fine liquid flow through the filter mesh or channel, avoiding the formation of a secondary oxide film during the turbulent entrainment of the melt. The depth of the filter H is related to the total pressure head of the melt. The total pressure head H of the melt is total = geometric head Hg + static head Hp + velocity head Hv, where geometric head Hg = filter depth H, Hp = P / (ρ*g), P is the pressure of the melt, ρ is the density of the melt, g represents the acceleration of gravity, and velocity head Hv = v 2 / (2g), v is the velocity of the melt, and g is the acceleration of gravity. The larger H is, the greater the total pressure head is, and the faster the filter screen filters. By adjusting H, the melt filtering speed is ensured to meet the production cycle of squeeze casting.

[0052] Another specific embodiment of the present invention provides an extrusion casting method, which at least includes: the pressure chamber cylinder is tilted out to prepare for receiving materials, the above-mentioned extrusion casting pressure chamber melt purification device is first placed at the material receiving port of the pressure chamber cylinder, and then the melt is poured into the pressure chamber cylinder through a filter screen. After the extrusion casting pressure chamber melt purification device is removed, the pressure chamber cylinder is returned to the normal position for filling.

[0053] Specifically, when the melt is poured into the pressure chamber cylinder, the melt is filtered by the extrusion casting pressure chamber melt purification device to remove impurities such as oxide film and refining agent contained in the melt, which can ensure that the finished product gradually contains a lower oxide film and ensure product quality. In addition, the filter can change the movement form of the falling melt to avoid the formation of oxide film again during the turbulent entrainment of the melt, thereby further ensuring product quality.

[0054] Furthermore, after the squeeze casting pressure chamber melt purification device is removed, a new filter screen is replaced, and then the next casting process is carried out.

[0055] Specifically, open the locking piece, separate the upper fixing piece and the lower fixing piece, remove the used filter, replace the new filter, match the upper fixing piece with the lower fixing piece, and install the locking piece. The entire filter replacement time must be less than the time interval for the new material spoon to start pouring the material. Using a new filter can prevent the oxides and slags remaining on the used filter from clogging the filter, thereby ensuring the filtering effect.

[0056] The present invention is further described in detail below in conjunction with specific embodiments.

[0057] Example 1

[0058] Squeeze casting chamber melt purification device, such as Figure 1 As shown, it includes a filter screen 1, a hollow annular upper fixing member 3 and a lower fixing member 2. The lower fixing member 2 includes a main body 20. The bottom surface of the main body 20 is provided with a step 21 along the periphery of the main body 20. The outer diameter of the step 21 is slightly smaller than the inner diameter of the top of the pressure chamber cylinder, so as to facilitate the step 21 to be placed in the pressure chamber cylinder. The bottom surface of the upper fixing member 3 is provided with an annular pressure groove, and the main body 20 is provided with a convex ridge 22 that matches the pressure groove. The inner diameter of the convex ridge 22 is larger than the outer diameter of the step 21. When the upper fixing member 3 is placed on the lower fixing member 2, the convex ridge 22 can be embedded in the pressure groove. The lower fixing member 2 is provided with a handle 23 for taking and placing the squeeze casting pressure chamber melt purification device.

[0059] The filter screen 1 has a "U" cross section, including a filter portion 11 and a horizontal mounting portion 12. The mounting portion 12 is placed on the lower fixing member 2, and the upper fixing member 3 is placed on the lower fixing member 2, so that the convex ridge 22 is embedded in the pressing groove to clamp the mounting portion 12, and then the upper fixing member 3 and the lower fixing member 2 are clamped with a dovetail clamp 4 to lock them to prevent the filter screen 1 from being rushed into the pressing chamber cylinder when pouring the material. The filter screen 1 has a mesh number of 20 and a depth of 50 mm. This mesh number and depth can better filter the melt and ensure the filtering speed of the melt.

[0060] Example 2

[0061] Squeeze casting method, combined with Figure 2 and Figure 3 , including: starting a 400T extrusion casting machine, tilting out a pressure chamber cylinder 5, the diameter of the pressure chamber cylinder 5 is φ80mm, placing the extrusion casting pressure chamber melt purification device in Example 1 on the top of the pressure chamber cylinder 5, so that the filter screen 1 is located in the pressure chamber cylinder 5, using a material spoon 8 to pour the A356.2 aluminum alloy melt into the filter screen 1, the single scooping amount is 2kg, and the pouring time is 2 to 3s. After the pouring and filtering is completed, the pressure chamber cylinder 5 is straightened, moved vertically upward, and docked with the gate in the mold. After the docking is completed, the injection filling and pressure holding are carried out according to the set molding parameters. After the pressure holding is completed, the pressure chamber cylinder 5 retreats downward and tilts out to the receiving side, and then the mold is opened and the steering knuckle casting is taken out.

[0062] The macro fracture of the steering knuckle casting is as follows: Figure 4 As mentioned above, the fracture SEM photos are as follows Figure 5 As shown by Figure 4 It can be seen that the fracture color of the casting is uniform and consistent, and there is no obvious abnormal regional organization. Figure 5 It can be seen that the fracture surface is composed of obvious dimples and tear edges.

[0063] The mechanical properties of the steering knuckle casting were tested after T6 heat treatment. The stress-strain curve obtained from the test is as follows: Figure 6 shown.

[0064] Comparative Example 1

[0065] Squeeze casting method, combined with Figure 7 , including: starting the 400T extrusion casting machine, pouring out the pressure chamber cylinder 5, the diameter of the pressure chamber cylinder 5 is φ80mm, using the material spoon 8 to pour the A356.2 aluminum alloy melt into the pressure chamber cylinder 5, the single scooping amount is 2kg, and the pouring time is 2-3s. After the pouring and filtering is completed, the pressure chamber cylinder 5 is straightened, moved vertically upward, and docked with the gate in the mold. After the docking is completed, the injection filling and pressure holding are carried out according to the set molding parameters. After the pressure holding is completed, the pressure chamber cylinder 5 retreats downward and pours out to the receiving side, and then the mold is opened and the steering knuckle casting is taken out.

[0066] The macro fracture of the steering knuckle casting is as follows: Figure 8 Said by Figure 8 It can be seen from the figure that there are abnormal areas with inconsistent colors on the casting fracture surface. Further analysis is performed using SEM photos, such as Fig. 9 As shown in the figure, there is an abnormal area structure with a diameter of about 1mm on the fracture surface, and there are large-sized oxide film defects. The oxide film is a brittle cleavage fracture with wrinkles, smoothness, and no obvious dimples. Fig. 9 The morphology of the dimples corresponds to the abnormal area in the middle, and is in sharp contrast with the normal area.

[0067] The mechanical properties of the steering knuckle casting were tested after T6 heat treatment. The stress-strain curve obtained from the test is as follows: Fig.10 As shown, combined Fig. 9 and Fig.11 Due to the existence of the abnormal area, the effective bearing area will be reduced, cracks will initiate and expand rapidly, and finally the mechanical properties, especially the elongation, will be rapidly reduced.

[0068] In summary, the extrusion casting pressure chamber melt purification device of the present invention is used in the extrusion casting process. On the one hand, the melt is filtered and purified to effectively remove slag inclusions such as oxide film and refining agent contained in the melt; on the other hand, the movement form of the melt is improved. Under the action of the filter, the melt falls into the pressure chamber in the form of a fine liquid flow, avoiding the formation of a secondary oxide film during the turbulent entrainment of the melt. Therefore, under the comprehensive effect, the mechanical properties stability of the casting can be improved, the service requirements of the casting can be met, and the yield rate of the casting can also be improved.

[0069] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0070] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A squeeze casting pressure chamber melt purification device, characterized in that: It is used to be placed at the receiving port of the pressure chamber cylinder so that the melt is diverted and falls into the pressure chamber cylinder, and at least includes: Filter; The lower fixing member includes a main body portion supporting the filter screen, wherein the main body portion is used to cooperate with the material receiving port of the pressure chamber cylinder; The upper fixing piece cooperates with the lower fixing piece to clamp and fix the filter screen; The movable part is connected with the lower fixed part and is used for taking and placing the filter screen on the pressure chamber cylinder.

2. The squeeze casting pressure chamber melt purification device according to claim 1, characterized in that: The middle part of the filter screen is sunken downward to form a chamber, and the depth of the sunken chamber is 30 to 50 mm.

3. The squeeze casting pressure chamber melt purification device according to claim 1, characterized in that: The filter mesh number is 10 to 20 meshes.

4. The squeeze casting pressure chamber melt purification device according to claim 1, characterized in that: The main body is provided with a first pressing portion, and the upper fixing member is provided with a second pressing portion matched with the first pressing portion.

5. The squeeze casting pressure chamber melt purification device according to claim 1, characterized in that: It also includes a locking piece for locking the upper fixing piece and the lower fixing piece.

6. The squeeze casting pressure chamber melt purification device according to claim 1, characterized in that: The main body is provided with a guide portion for cooperating with the material receiving opening of the pressure chamber tube.

7. The squeeze casting pressure chamber melt purification device according to claim 1, characterized in that: The lower fixing piece is in the shape of a ring or a hollow polygon.

8. The squeeze casting pressure chamber melt purification device according to claim 1, characterized in that: The upper fixing piece is in the shape of a ring or a hollow polygon.

9. A squeeze casting method, characterized in that: At least: The pressure chamber cylinder is tilted out to prepare for receiving materials. First, the squeeze casting pressure chamber melt purification device described in any one of claims 1 to 8 is placed at the material receiving port of the pressure chamber cylinder, and then the melt is poured into the pressure chamber cylinder through the filter screen. After the squeeze casting pressure chamber melt purification device is taken away, the pressure chamber cylinder is returned to the normal position for filling.

10. The squeeze casting method according to claim 9, characterized in that: After removing the squeeze casting pressure chamber melt purification device, replace it with a new filter before the next casting process.

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