Low-pressure casting mold with temperature control feeding function

Abstract

A heat conduction sleeve is arranged between a conventional liquid lifting assembly and a pouring gate, the temperature rise of the heat conduction sleeve is controlled by an induction heater, the temperature of molten metal passing through the heat conduction sleeve is regulated and controlled, the controllability is high, and the feeding capacity to a cavity can be adjusted at different stages of casting. The casting process provided by the utility model has the advantage of high feeding efficiency, the size of the used pouring gate is far lower than that of the prior art, and the investment of a single set of die is reduced. And meanwhile, the filter screen made of a high-heat-conduction material is arranged, heat of the induction heater can be rapidly transferred, molten metal is not prone to being condensed on the surface of the filter screen, and then the cleaning-free effect is achieved. The pouring gate is located on the inner side of the cavity, only a small part of molten metal is solidified on the inner surface of a casting after forming is completed, the time for sawing the pouring gate in the conventional technology is saved, and the production efficiency of the casting is greatly improved.

Description

Technical Field

[0001] This utility model relates to a casting mold, and more particularly to a low-pressure casting mold with temperature-controlled feeding. Background Technology

[0002] Low-pressure casting is a common method for casting workpieces. The working principle is that the molten metal in the holding furnace rises under pressure into the part cavity of the metal mold, and then solidifies and forms the part under low pressure. Figure 1 and Figure 2 This demonstrates a low-pressure casting mold for an automobile steering knuckle, with the upper and lower molds forming the molding cavity of the casting.

[0003] Feeding in castings is a problem that must be addressed during the casting process. This is because the structure and wall thickness distribution of parts are never always ideal. Local areas that are too thick and solidify slowly will form hot spots inside the part. Often, it is necessary to cool these areas and then increase the feeding effect at the front of the mold. In short, the front of the mold at these locations requires a higher part temperature to create a temperature gradient.

[0004] Common methods of compensation include Figure 1 As shown, a gate is placed between the bottom of the mold cavity and the liquid riser assembly as a transition and feeding zone for casting. Molten metal enters the part cavity through the gate, and pressure continues to be supplied to the gate after the mold cavity is filled, thus helping to feed the part body. To ensure sufficient feeding capacity of the gate, it is necessary to ensure that the gate has a certain mass to create a temperature gradient. From Figure 2 It is evident that the bottom gate is quite large, typically accounting for 15-25% of the casting weight. This portion of the gate needs to be removed by sawing after molding, impacting the casting's processing efficiency. Since each part requires sawing, even if the sawn gate can be recycled and remelted, some burn-off still occurs. Furthermore, the large gate thickness results in a low actual part yield. Cooling the gate in the later stages of casting takes time, increasing the process cycle time. Prolonged heating and cooling adjustments also increase fatigue in the gate area, posing a risk of mold cracking. Utility Model Content

[0005] To solve the above-mentioned technical problems, this utility model provides a low-pressure casting mold with temperature control and feeding, including an upper mold and a lower mold arranged opposite to each other. The upper mold is driven by a driving mechanism to press down, forming a cavity for forming molten metal between the upper mold and the lower mold. The bottom of the lower mold is provided with a liquid lifting component connected to a heat preservation furnace, and the bottom of the upper mold is equipped with a flow divider cone. A gate is formed between the liquid lifting component and the flow divider cone.

[0006] A heat-conducting sleeve is provided between the gate and the liquid-lifting assembly, with the centers of both ends of the heat-conducting sleeve connected to the liquid-lifting assembly and the gate, respectively; it also includes an induction heater connected to the control center, with the induction coil of the induction heater looped inside the heat-conducting sleeve, and the temperature of the molten metal passing through the heat-conducting sleeve is regulated by electromagnetic induction.

[0007] Furthermore, the metal mold also includes a filter screen for filtering molten metal, the filter screen being arranged in a ring on the inner side of the heat-conducting sleeve, and the outer side of the filter screen being in contact with the inner wall of the heat-conducting sleeve.

[0008] Furthermore, the gate is formed inside the cavity.

[0009] Furthermore, the filter screen is a molybdenum alloy filter screen.

[0010] Furthermore, the diverting cone is a tungsten carbide mold.

[0011] Furthermore, the heat-conducting sleeve is composed of two L-shaped metal fasteners arranged vertically, with the opposing circumferential surfaces of the two metal fasteners forming a heating cavity for storing the induction coil.

[0012] Furthermore, the filter screen is located at the pipe opening position near the gate side.

[0013] Furthermore, an annular groove is provided on the inner circumferential surface of the heat-conducting sleeve, and the side of the filter screen is installed in the annular groove.

[0014] Furthermore, the top of the diversion cone is connected to a circulating water cooling channel.

[0015] Furthermore, the side cross-section of the diverter cone is an arc-shaped structure that is wider at the top and narrower at the bottom.

[0016] This invention provides a low-pressure casting mold with temperature-controlled feeding, comprising an upper mold and a lower mold arranged opposite each other. A heat-conducting sleeve is provided between the conventional liquid riser assembly and the gate. The temperature of the heat-conducting sleeve is controlled by an induction heater, allowing for regulation and control of the temperature of the molten metal passing through the heat-conducting sleeve. This provides strong controllability and enables adjustment of the feeding capacity of the cavity at different stages of casting. The casting mold provided by this invention has the advantage of high feeding efficiency. The size of the gate used is much smaller than that of existing technologies, reducing the investment in a single mold set. At the same time, the small-sized gate can reduce fatigue cracking caused by cooling water cooling and extend the mold life.

[0017] This invention also incorporates a filter screen made of a highly thermally conductive material, which can quickly transfer the heat from the induction heater. The molten metal is less likely to condense on the surface of the filter screen, thus achieving a cleaning-free effect.

[0018] The gate of this invention is located inside the cavity. After molding, only a small portion of the molten metal solidifies on the inner surface of the casting. This casting allowance can be processed in the later necessary machining stage, saving the time of sawing the gate in conventional technology and greatly improving the production efficiency of castings. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a low-pressure casting mold in the prior art;

[0020] Figure 2 This is an exploded diagram of a low-pressure casting mold in the existing technology;

[0021] Figure 3 This is a schematic diagram of the appearance of the low-pressure casting mold of this utility model;

[0022] Figure 4 This is a schematic diagram of the low-pressure casting mold of this utility model;

[0023] Figure 5 This is a schematic diagram showing the positions of the flow divider cone and the gate within the mold cavity of this utility model;

[0024] Figure 6 This is an exploded schematic diagram of the gate and runner of this utility model;

[0025] Figure 7 This is a schematic diagram showing the position of the induction coil of this utility model;

[0026] Figure reference numerals: 1. Upper mold; 2. Lower mold; 3. Cavity; 4. Liquid riser assembly; 5. Diverter cone; 6. Gate; 7. Filter screen; 8. Induction coil; 9. Heat-conducting sleeve; 10. Mesh support; 11. Annular groove. Detailed Implementation

[0027] like Figures 3 to 5 The diagram illustrates a temperature-controlled, low-pressure casting mold, comprising an upper mold 1 and a lower mold 2 arranged opposite to each other. A cavity 3 for forming molten metal is formed between the upper mold 1 and the lower mold 2. The upper mold 1 is driven downward by a vertically arranged drive mechanism, causing the upper mold 1 to close with the lower mold 2. A liquid lifting assembly 4 is connected to the bottom of the lower mold 2. The liquid lifting assembly generally consists of a liquid lifting pipe and a ceramic filler core installed on the top of the liquid lifting pipe. The other end of the liquid lifting assembly 4 is connected to a molten metal holding furnace. Molten metal in the holding furnace flows into the cavity 3 through the liquid lifting assembly 4 under external pressure. After the molten metal fills the cavity 3, it continues to be pressurized, and the molten metal in the cavity 3 solidifies and forms under low pressure. A flow divider cone 5 is installed at the bottom of the upper mold 1. The lower end of the flow divider cone 5 extends into the cavity 3. The side cross-section of the flow divider cone 5 roughly presents an arc-shaped structure that is wider at the top and narrower at the bottom. During the filling stage, the molten metal can flow from bottom to top along the outer arc of the flow divider cone 5 to fill the inner periphery of the cavity 3.

[0028] The lower mold 2 has a gate 6 at the top of the liquid riser assembly 4. The two ends of the gate 6 are connected to the liquid riser assembly 4 and the cavity 3, respectively. The molten metal flows from the liquid riser assembly 4 to the gate 6, and then is smoothly guided into the cavity 3 by the flow divider cone 5. During the solidification process of the molten metal, it plays a role in compensating for the shrinkage of the cavity 3. The opening of the gate 6 is generally designed with an arc-shaped concave structure that is wider at the top and narrower at the bottom, according to the shape of the flow divider cone 5 and the cavity 3, forming a shape with a reasonable wall thickness distribution to ensure the compensating effect on the forming of the cavity 3 as much as possible.

[0029] Unlike existing technologies that use a gate 6 to compensate for shrinkage in the cavity 3, this invention features a heating mechanism at the lower part of the gate 6. This mechanism adjusts the shrinkage level of the molten metal by changing the temperature of the molten metal flowing through the gate 6 in real time. The heating mechanism includes a heat-conducting sleeve 9 located below the gate 6 in the lower mold 2. The centers of both ends of the heat-conducting sleeve 9 are connected to the liquid lifting assembly 4 and the gate 6, respectively. The heat-conducting sleeve 9 can heat the molten metal entering the runner before the gate 6.

[0030] This utility model's heat-conducting sleeve 9 uses induction heating to heat the runner. The principle of induction heating is to generate an alternating magnetic field through alternating current. Eddy currents are generated inside the metal conductor within this alternating magnetic field, rapidly increasing the conductor's temperature. Induction heaters have the advantage of fast heating speed. Simultaneously, the induction heater can control the heating program according to preset parameters, possessing a certain degree of automated operation capability. For example... Figure 6 and Figure 7 As shown, the heat-conducting sleeve 9 has an annular heating cavity, and the induction coil 8 of the induction heater is arranged in the heating cavity. The wire end of the induction coil 8 passes through the heat-conducting sleeve 9 and is connected to an external power source.

[0031] In this embodiment, the heat-conducting sleeve 9 is composed of two L-shaped metal fasteners arranged vertically. The opposing circumferential surfaces of the two metal fasteners form the heating cavity for storing the induction coil 8. The metal fasteners are made of high heat-resistant mold steel, which can quickly receive the heat generated by the heating induction coil 8 and provide external shielding for the induction coil 8.

[0032] The principle of this invention is to increase the temperature of the molten metal at the gating point through induction heating, thereby improving the degree of metal feeding. Unlike existing technologies, it does not require storing a large amount of feeding molten metal, thus greatly reducing the space occupied by the gating gate 6. Furthermore, unlike existing technologies where the gating gate 6 is formed below the cavity 3, requiring the excess gating gate 6 to be sawn off along the bottom of the cavity 3 after casting, in this embodiment, because the space occupied by the gating gate 6 is small, it can be further placed inside the cavity 3. A small amount of molten metal is formed together with the cavity 3 at the gating point. This casting allowance can be removed in the subsequent machining process without needing to saw off the lower gating gate 6.

[0033] In this embodiment, the runner cone 5 is made of a high thermal conductivity material, such as tungsten carbide alloy with a thermal conductivity of not less than 80 W / (m*K), which is twice that of ordinary mold steel. During the later stages of molten metal solidification, circulating water circulates inside the runner cone 5 for cooling. Due to the smaller volume of the gating 6 and the improved material of the runner cone 5, the heat in the middle area of ​​the cavity 3 and inside the gating 6 is quickly carried away, greatly reducing the cooling time of the gating 6. After the gating 6 solidifies, the mold can be opened and the part removed for the next cycle. In each low-pressure casting cycle, conventional casting processes typically require more than 70 seconds for cooling the gating 6 during the later stages of solidification, while the device provided in this embodiment can reduce the cooling time of the gating 6 to about 10-20 seconds.

[0034] Because the molten metal may contain oxide slag, impurities from the crucible or degassing consumables, or residues from alloy or refining agent treatment, existing technologies place a [material] at gate 6. Figure 2 The filter screen 7 is shown. There are typically two ways to install the filter screen 7: one is to use a disposable fiberglass filter screen, placed manually, allowing the cut gate 6 to be remelted in the furnace; the other is to use a metal filter screen placed by a robotic arm, but iron contamination prevents the gate from being reused. The former method cannot guarantee that the filter screen 7 is placed correctly or without omissions, while the latter has the problem of low material utilization.

[0035] Similar to existing technologies, this embodiment includes a filter screen 7 for filtering molten metal. The filter screen 7 is annularly positioned within the runner of the heat-conducting sleeve 9, fully covering the flow area of ​​the molten metal. The filter screen 7 is made of a highly heat-resistant and thermally conductive metal material, such as a molybdenum alloy with a thermal conductivity of not less than 120 W / (m*K). After the induction coil 8 heats up, the filter screen 7 can rapidly heat up through the heat-conducting sleeve 9, accelerating the flow rate of the molten metal through the induction coil 8. The filter screen 7 is preferably positioned near the nozzle 6, allowing the molten metal to flow directly into the nozzle 6 after passing through the filter screen 7, thus heating the molten metal at the nozzle 6 and improving the feeding efficiency.

[0036] Traditional filter screens 7 are typically disposable structures, fixed inside the gating 6 by an external mesh support 10, and replaced after each casting. In this embodiment, an annular groove 11 is further provided on the inner circumferential surface of the heat-conducting sleeve 9. The annular groove 11 acts as a mesh support for the filter screen 7, and fixing the filter screen 7 within the annular groove 11 reduces the frequency of replacement and prevents the filter screen 7 from being missed or misaligned.

[0037] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A temperature controlled feeder low pressure casting mold characterized by: The mould comprises upper die (1) and lower die (2) arranged oppositely, the upper die (1) is driven by driving mechanism to press down, the cavity (3) for forming metal liquid is formed between the upper die (1) and the lower die (2), the bottom of the lower die (2) is provided with the lifting assembly (4) communicated with the holding furnace, the bottom of the upper die (1) is provided with the flow dividing cone (5), the pouring gate (6) is formed between the lifting assembly (4) and the flow dividing cone (5). The pouring gate (6) and the lifting assembly (4) are provided with the heat conducting sleeve (9), the two ends of the heat conducting sleeve (9) are communicated with the lifting assembly (4) and the pouring gate (6) respectively, the inductive heater connected to the control center is further included, the inductive coil (8) of the inductive heater is arranged in the heat conducting sleeve (9), and the temperature of the metal liquid passing through the heat conducting sleeve (9) is regulated by electromagnetic induction.

2. A low pressure casting mold with temperature controlled feeding according to claim 1, characterized in that: The filter screen (7) for filtering metal liquid is further included, the filter screen (7) is arranged on the inner side of the heat conducting sleeve (9), and the outer side of the filter screen (7) is in contact with the inner wall of the heat conducting sleeve (9).

3. A temperature controlled feeding low pressure casting mold as set forth in claim 1, characterized by: The pouring gate (6) is formed on the inner side of the cavity (3).

4. A temperature controlled feeding low pressure casting mold as set forth in claim 2, characterized by: The filter screen (7) is molybdenum alloy filter screen.

5. A temperature controlled feeding low pressure casting mold as set forth in claim 1, characterized by: The flow dividing cone (5) is tungsten steel die.

6. A temperature controlled feeding low pressure casting mold as set forth in claim 4, characterized by: The heat conducting sleeve (9) is composed of two metal fasteners with L-shaped cross section, and the opposite circumferential surfaces of the two metal fasteners form a heating cavity for storing the inductive coil (8).

7. A temperature controlled feeding low pressure casting mold as set forth in claim 4 wherein: The filter screen (7) is located at the pipe opening position close to the pouring gate (6).

8. A temperature controlled feeding low pressure casting mold as set forth in claim 6, characterized by: The inner circumferential surface of the heat conducting sleeve (9) is provided with annular clamping groove (11), and the side edge of the filter screen (7) is installed in the annular clamping groove (11).

9. A temperature controlled feeding low pressure casting mold as set forth in claim 1 wherein: The top of the flow dividing cone (5) is connected with the circulating water cooling channel.

10. A temperature controlled feeding low pressure casting mold as set forth in claim 1, characterized by: The side cross section of the flow dividing cone (5) is arc-shaped structure with wide top and narrow bottom.

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