Vacuum die-casting mold and exhaust passage structure thereof

Abstract

The application discloses a kind of exhaust passage structures, including air inlet, exhaust passage and exhaust port in turn;The exhaust passage includes at least two exhaust passage sections and at least one exhaust passage transition section, at least two exhaust passage sections are arranged at intervals, and any two adjacent exhaust passage sections are connected by an exhaust passage transition section, the length of the exhaust passage section and its cross section equivalent radius ratio is 5-30, the cross-sectional area ratio of any one exhaust passage section and the next exhaust passage section in the exhaust passage is 1.2-1.6;Each section cross-sectional area gradually changes according to certain proportion, the connection between different sections is tapered structure, and the taper is between 15-45 °.The application also discloses a kind of vacuum die casting mould containing multiple exhaust passage structures, gas flows smoothly during die casting vacuumizing process, and is not prone to gas whirl, vortex, shock wave and blockage channel etc., can effectively reduce cavity gas pressure, improve exhaust efficiency.

Description

Technical Field

[0001] This invention relates to the field of die casting, and more specifically to a vacuum die casting mold and its exhaust channel structure. Background Technology

[0002] Die casting is one of the main forming methods for aluminum alloy components, offering advantages such as high dimensional accuracy and high production efficiency. However, conventional die casting, characterized by high speed and high pressure, is prone to turbulence, leading to gas entrapment, voids, and reduced casting performance. During subsequent heat treatment, the thermal expansion of these voids causes blistering on the casting surface. Compared to conventional die casting, vacuum die casting uses a specific device to remove gas from the mold cavity before filling, reducing the mold cavity gas pressure during filling and thus minimizing gas entrapment. This effectively reduces porosity and improves the mechanical properties of the casting.

[0003] To improve the quality of die-cast parts and reduce the content of entrained gas, various vacuum systems have been introduced both domestically and internationally, mainly focusing on the research and development of efficient and stable mechanical vacuum valves, as reported in patents CN105697797B and CN09115777U.

[0004] Although there are numerous studies and reports on vacuum valve technology, the purpose of vacuum die casting is to minimize the cavity gas pressure and maximize the cavity vacuum level during the die casting filling process. During vacuuming, the reduction in cavity gas pressure depends not only on the vacuum pump and vacuum valve but also on the flow behavior of the gas from the cavity through the exhaust duct to the vacuum valve. Gas flow studies show that gas flow in pipes with different cross-sectional areas can experience swirling, eddies, shock waves, and blockages. Therefore, the exhaust duct structure and its cross-sectional area will affect the gas flow and cavity vacuum level during the vacuum die casting process. However, no research or specific technical reports have been found on exhaust duct structure design optimized for exhaust. Summary of the Invention

[0005] In order to overcome the shortcomings and disadvantages of the prior art, the primary objective of this invention is to provide an exhaust channel structure that can optimize the airflow path, improve exhaust efficiency, and reduce the gas pressure in the cavity of a vacuum die-casting mold.

[0006] A second objective of the present invention is to provide a vacuum die-casting mold that can reduce the cavity gas pressure.

[0007] The primary objective of this invention can be achieved through the following technical solution:

[0008] An exhaust duct structure includes an air inlet, an exhaust duct, and an exhaust outlet in sequence; the exhaust duct includes at least two exhaust duct segments and at least one exhaust duct transition segment, the at least two exhaust duct segments are spaced apart, and any two adjacent exhaust duct segments are connected by an exhaust duct transition segment, the ratio of the length of the exhaust duct segment to its equivalent cross-sectional radius is 5 to 30, and the ratio of the cross-sectional area of ​​any one exhaust duct segment to the cross-sectional area of ​​the next exhaust duct segment is 1.2 to 1.6.

[0009] Preferably, the length of the exhaust duct section is less than 100 mm.

[0010] Preferably, the longitudinal section of the exhaust duct transition section is a tapered structure with a taper of 15 to 45°.

[0011] Preferably, the exhaust duct consists of an exhaust duct section, an exhaust duct transition section, and an exhaust duct section, which are sequentially arranged from the air inlet to the exhaust outlet, and are repeated in a cycle according to the required length of the exhaust duct.

[0012] Preferably, the cross-sectional shape of the exhaust duct is circular or rectangular with rounded corners.

[0013] The second objective of this invention can be achieved through the following technical solution:

[0014] A vacuum die-casting mold includes a material cake, a die-casting cavity, a vacuum shut-off valve piston, and multiple exhaust channel structures as described above.

[0015] Before die casting, the gas in the die cake and die casting cavity is removed through the exhaust channel structure. When the required vacuum level is reached, the vacuum shut-off valve piston is closed to complete the exhaust process.

[0016] During the vacuum die casting process, the air inlet of the exhaust channel structure is connected to the die casting cavity, and the exhaust outlet of the exhaust channel structure is connected to the vacuum shut-off valve piston.

[0017] As a preferred embodiment, the exhaust duct structure includes three exhaust ducts, namely a first exhaust duct, a second exhaust duct, and a third exhaust duct, wherein the first exhaust duct, the second exhaust duct, and the third exhaust duct are connected in parallel, and the first exhaust duct and the third exhaust duct are symmetrically arranged.

[0018] Preferably, the first exhaust duct includes a first exhaust duct inlet, a first exhaust duct section, a first exhaust duct transition section, a second exhaust duct section, a second exhaust duct transition section, a third exhaust duct section, and a first exhaust duct outlet;

[0019] The second exhaust duct includes a second exhaust section inlet, a fourth exhaust section, a third exhaust section transition section, a fifth exhaust section, and a second exhaust duct outlet;

[0020] The third exhaust duct includes the third exhaust duct inlet, the sixth exhaust duct section, the fourth exhaust duct transition section, the seventh exhaust duct section, the fifth exhaust duct transition section, the eighth exhaust duct section, and the third exhaust duct outlet.

[0021] Preferably, the cross-sectional area ratio of the first exhaust duct section, the second exhaust duct section, and the third exhaust duct section is 1:1.44:1.96.

[0022] Preferably, the longitudinal sections of the first and second exhaust duct transition sections are both conical structures with a larger outer diameter and a smaller inner diameter, with tapers of 35° and 30° respectively; the longitudinal section of the third exhaust duct transition section is a conical structure with a larger outer diameter and a smaller inner diameter, with a taper of 30°; the longitudinal sections of the fourth and fifth exhaust duct transition sections are both conical structures with a larger outer diameter and a smaller inner diameter, with tapers of 35° and 30° respectively.

[0023] As another preferred embodiment, the exhaust duct structure includes a fourth exhaust duct and a fifth exhaust duct arranged symmetrically, wherein the fourth exhaust duct and the fifth exhaust duct share a seventh exhaust duct transition section and an eleventh exhaust duct section as well as an exhaust port of the fourth exhaust duct;

[0024] The fourth exhaust duct includes the fourth exhaust duct inlet, the ninth exhaust duct section, the sixth exhaust duct transition section, the tenth exhaust duct section, the seventh exhaust duct transition section, and the eleventh exhaust duct section, as well as the fourth exhaust duct outlet.

[0025] The fifth exhaust duct includes the fifth exhaust duct inlet, the twelfth exhaust duct section, the eighth exhaust duct transition section, and the thirteenth exhaust duct section.

[0026] Preferably, the ratio of the sum of the cross-sectional areas of the ninth and twelfth exhaust duct sections, the sum of the cross-sectional areas of the tenth and thirteenth exhaust duct sections, and the cross-sectional area of ​​the eleventh exhaust duct section is 1:1.5:2.

[0027] Preferably, the longitudinal sections of the sixth and eighth exhaust duct transition sections are both tapered structures with a larger outer diameter and a smaller inner diameter, with a taper of 45°, and the longitudinal section of the seventh exhaust duct transition section is a right-angled structure with a diagonal line, with a slope of 45°.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) The exhaust channel structure designed in this invention is simple, easy to implement and low in manufacturing cost. The exhaust channel structure can be designed according to the mold size and the required length of the exhaust channel. Specifically, multiple exhaust channel sections and exhaust channel transition sections are designed from the air inlet of the exhaust channel structure to the exhaust outlet of the exhaust channel structure.

[0030] (2) When the exhaust channel structure of the present invention is evacuated, the gas flows smoothly in the exhaust channel, and it is not easy to generate swirling, eddy currents, shock waves and blockage of the channel. It can effectively reduce the gas pressure in the cavity and improve the exhaust efficiency.

[0031] (3) The exhaust channel structure described in this invention allows gas to flow out of the mold cavity more quickly, and the gas pressure in the die-casting mold cavity decreases rapidly, which can improve production efficiency and casting quality. Attached Figure Description

[0032] Figure 1 A schematic diagram of the vacuum die-casting mold structure provided for Comparative Example 1 and Embodiment 1 of the invention;

[0033] Figure 2 The curves showing the average pressure change over time inside the lower cavity of the exhaust duct in Comparative Example 1 and Example 1 are provided.

[0034] Figure 3 A schematic diagram of the vacuum die-casting mold structure provided for Comparative Example 2 and Embodiment 2 of the invention;

[0035] Figure 4 The invention provides curves showing the average pressure change over time within the lower cavity of the exhaust duct in Comparative Example 2 and Example 2.

[0036] Among them, 1-material cake, 2-die casting cavity, 3-first exhaust channel, 4-second exhaust channel, 5-third exhaust channel, 6-vacuum shut-off valve piston, 7-fourth exhaust channel, 8-fifth exhaust channel, 31-first exhaust channel section, 32-first exhaust channel transition section, 33-second exhaust channel section, 34-second exhaust channel transition section, 35-third exhaust channel section, 41-fourth exhaust channel section, 42-third exhaust channel transition section, 43-fifth exhaust channel section, 51-sixth exhaust channel section, 52-fourth exhaust channel transition section, 53-sixth exhaust channel section, 54-fifth exhaust channel transition section, 55-eighth exhaust channel section; 71-ninth exhaust channel section, 72-sixth exhaust channel transition section, 73-tenth exhaust channel section, 74-seventh exhaust channel transition section, 75-eleventh exhaust channel section, 81-twelfth exhaust channel section, 82-eighth exhaust channel transition section, 83-thirteenth exhaust channel section. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the implementation and protection of this invention are not limited thereto.

[0038] Comparative Example 1

[0039] like Figure 1As shown, this comparative example designs a vacuum die-casting mold (1) with three exhaust channels, namely the first exhaust channel 3, the second exhaust channel 4, and the third exhaust channel 5, each with a circular cross-sectional shape. Table 1 shows the dimensional parameters of the exhaust channel structure in the vacuum die-casting mold described in this comparative example, where L is the length of each segment of the exhaust channel, and r and S are the cross-sectional radius and cross-sectional area of ​​each segment of the exhaust channel.

[0040] The first exhaust duct 3 includes a first exhaust duct inlet, a first exhaust duct section 31, a first exhaust duct transition section 32, a second exhaust duct section 33, a second exhaust duct transition section 34, a third exhaust duct section 35, and a first exhaust duct outlet. The first exhaust duct section 31 has a length L31 of 80 mm, a cross-sectional radius r31 of 5 mm, and a cross-sectional area S31 of 78.5 mm². 2 The second exhaust duct section 33 has a length L33 of 70 mm, a cross-sectional radius r33 of 4 mm, and a cross-sectional area S13 of 50.26 mm². 2 The third exhaust duct section 35 has a length L35 of 60mm, a cross-sectional radius r35 of 3mm, and a cross-sectional area S35 of 28.27mm². 2 The ratio of the cross-sectional area S31 of the first exhaust duct section, the cross-sectional area S33 of the second exhaust duct section, and the cross-sectional area S35 of the third exhaust duct section is 2.78:1.78:1. The longitudinal sections of the first exhaust duct transition section 32 and the second exhaust duct transition section 34 are both tapered structures with a smaller outer section and a larger inner section, with tapers of 60° and 75° respectively.

[0041] The second exhaust duct 4 includes a second exhaust section inlet, a fourth exhaust section 41, a third exhaust section transition section 42, a fifth exhaust section 43, and a second exhaust duct outlet; the fourth exhaust section 41 has a length L41 of 85 mm, a cross-sectional radius r41 of 6.5 mm, and a cross-sectional area S41 of 132.73 mm². 2 The fifth exhaust duct section 43 has a length L43 of 90mm, a cross-sectional radius r43 of 5mm, and a cross-sectional area S43 of 78.5mm². 2 The ratio of the cross-sectional area S41 of the fourth exhaust duct section and the cross-sectional area S43 of the fifth exhaust duct section in the second exhaust duct 4 is 1.69:1. The longitudinal section of the transition section 42 of the third exhaust duct is a conical structure with a smaller outer diameter and a larger inner diameter, with a taper of 60°.

[0042] The third exhaust duct 5 includes a third exhaust duct inlet, a sixth exhaust duct section 51, a fourth exhaust duct transition section 52, a seventh exhaust duct section 53, a fifth exhaust duct transition section 54, an eighth exhaust duct section 55, and a third exhaust duct outlet.

[0043] The sixth exhaust duct section 51 has a length L51 of 80mm, a cross-sectional radius r51 of 5mm, and a cross-sectional area S51 of 78.5mm².2 The seventh exhaust duct section 53 has a length L53 of 70mm, a cross-sectional radius r53 of 6mm, and a cross-sectional area S15 of 50.26mm². 2 The eighth exhaust duct section 55 has a length L55 of 60mm, a cross-sectional radius r55 of 3mm, and a cross-sectional area S55 of 28.27mm². 2 The cross-sectional areas of the sixth exhaust duct segment 51 (S51), the seventh exhaust duct segment 53 (S53), and the eighth exhaust duct segment 55 (S55) in the third exhaust duct satisfy the following relationship: S51:S53:S55 = 2.78:1.78:1. The longitudinal sections of the fourth exhaust duct transition segment 52 and the fifth exhaust duct transition segment 54 are both tapered structures with a smaller outer diameter and a larger inner diameter, with tapers of 60° and 75° respectively.

[0044] Table 1 shows the dimensional parameters of the vacuum die-casting mold (1) in Comparative Example 1.

[0045] serial number 31 33 35 41 43 51 53 55 r, mm 5 4 3 6.5 5 5 4 3 L, mm 80 70 60 85 70 80 70 60 <![CDATA[S,mm 2 ]]> 78.5 50.26 28.27 132.73 78.5 78.5 50.26 28.27

[0046] The first exhaust channel section 31, the fourth exhaust channel section 41, and the sixth exhaust channel section 51 are connected to the die-casting cavity 2, and the third exhaust channel section 35, the fifth exhaust channel section 43, and the eighth exhaust channel section 55 are connected to the vacuum shut-off valve piston 6. Before die-casting, the gas in the material cake 1 and the die-casting cavity 2 is evacuated through the first exhaust channel 3, the second exhaust channel 4, and the third exhaust channel 5. When the required vacuum level is reached, the vacuum shut-off valve piston 6 closes, stopping the evacuation.

[0047] The cold injection and evacuation process of a die-casting cavity was simulated using Fluent software. The initial gas pressure inside the cavity was 101325 Pa. The gas pressure variation curve of the cavity over time in this comparative example was obtained through numerical simulation, as shown below. Figure 2 As shown in the figure, the gas pressure curve results indicate that the exhaust duct cavity pressure drops more slowly and the exhaust efficiency is lower when using this comparative design.

[0048] Example 1

[0049] like Figure 1 As shown, this embodiment designs a vacuum die-casting mold (2) with three exhaust channels: the first exhaust channel 3, the second exhaust channel 4, and the third exhaust channel 5. The cross-sectional shape of each exhaust channel is circular. Table 1 shows the dimensional parameters of the exhaust channel structure described in this embodiment, where L is the length of each segment of the exhaust channel, r is the cross-sectional radius of each segment of the exhaust channel, and S is the cross-sectional area of ​​each segment of the exhaust channel. The vacuum die-casting mold exhaust channel structure (2) described in this embodiment is the same as the exhaust channel structure designed in Comparative Example 1, but the dimensional parameters are different. The specific dimensional parameters are shown in Table 1 below.

[0050] like Figure 1As shown, in this embodiment, the first exhaust duct 3 includes a first exhaust duct inlet, a first exhaust duct section 31, a first exhaust duct transition section 32, a second exhaust duct section 33, a second exhaust duct transition section 34, a third exhaust duct section 35, and a first exhaust duct outlet.

[0051] The first exhaust duct section 31 has a length L31 of 70 mm, a cross-sectional radius r31 of 5 mm, and a cross-sectional area S31 of 78.5 mm². 2 The second exhaust duct section 33 has a length L33 of 80 mm, a cross-sectional radius r33 of 6 mm, and a cross-sectional area S13 of 113.04 mm². 2 The third exhaust duct section 35 has a length L35 of 90mm, a cross-sectional radius r35 of 7mm, and a cross-sectional area S35 of 153.86mm². 2 The ratio of the cross-sectional areas of the first exhaust duct segment S31, the second exhaust duct segment S33, and the third exhaust duct segment S35 is 1:1.44:1.96. The longitudinal sections of the first exhaust duct transition section 32 and the second exhaust duct transition section 34 are both tapered structures with larger outer sections and smaller inner sections, with tapers of 35° and 30° respectively.

[0052] The second exhaust duct 4 includes a second exhaust section inlet, a fourth exhaust section 41, a third exhaust section transition section 42, a fifth exhaust section 43, and a second exhaust duct outlet; the fourth exhaust section 41 has a length L41 of 80 mm, a cross-sectional radius r41 of 6.5 mm, and a cross-sectional area S41 of 132.73 mm². 2 The fifth exhaust duct section 43 has a length L43 of 90 mm, a cross-sectional radius r43 of 7.5 mm, and a cross-sectional area S43 of 176.72 mm². 2 The cross-sectional areas of the fourth and fifth exhaust duct sections in the second exhaust duct 4, S41 and S43, satisfy the following relationship: S41:S43 = 1:1.33. The longitudinal section of the transition section 42 of the third exhaust duct is a conical structure with a smaller outer diameter and a larger inner diameter, with a taper of 30°.

[0053] The third exhaust duct 5 includes a third exhaust duct inlet, a sixth exhaust duct section 51, a fourth exhaust duct transition section 52, a seventh exhaust duct section 53, a fifth exhaust duct transition section 54, an eighth exhaust duct section 55, and a third exhaust duct outlet.

[0054] The sixth exhaust duct section 51 has a length L51 of 70mm, a cross-sectional radius r51 of 5mm, and a cross-sectional area S51 of 78.5mm². 2 The seventh exhaust duct section 53 has a length L53 of 80mm, a cross-sectional radius r53 of 6mm, and a cross-sectional area S15 of 113.04mm². 2The eighth exhaust duct section 55 has a length L55 of 90mm, a cross-sectional radius r55 of 7mm, and a cross-sectional area S55 of 155.86mm². 2 The cross-sectional area ratio of the sixth exhaust duct segment 51 (S51), the seventh exhaust duct segment 53 (S53), and the eighth exhaust duct segment 55 (S55) in the third exhaust duct 5 is 1:1.44:1.96. The longitudinal sections of the fourth exhaust duct transition segment 52 and the fifth exhaust duct transition segment 54 are both tapered structures with a smaller outer section and a larger inner section, with tapers of 35° and 30° respectively.

[0055] Table 2 shows the dimensional parameters of the vacuum die-casting mold (2) in Example 1.

[0056] serial number 31 33 35 41 43 51 53 55 r, mm 5 6 7 6.5 7.5 5 6 7 L, mm 70 80 90 80 90 70 80 90 <![CDATA[S,mm 2 ]]> 78.54 113.04 153.86 132.73 176.72 78.54 113.04 153.86

[0057] The cold injection and evacuation process of the die-casting cavity was simulated using Fluent software. The initial gas pressure inside the cavity was 101325 Pa. The curve of the cavity gas pressure changing with time obtained through numerical simulation in this embodiment is shown below. Figure 2 As shown in the figure. From the gas pressure curve results, it can be seen that the gas pressure in the cavity of the optimized and improved exhaust channel in Example 1 decreases significantly faster than that of the vacuum die-casting mold (1) described in Comparative Example 1 under the same evacuation time, thus improving the exhaust efficiency.

[0058] Comparative Example 2

[0059] like Figure 3 As shown, this comparative example designs a vacuum die-casting mold (3). The exhaust channel structure includes a fourth exhaust channel 7 and a fifth exhaust channel 8 symmetrically arranged. The fourth exhaust channel 7 and the fifth exhaust channel 8 have a seventh exhaust channel transition section 74 and an eleventh exhaust channel section 75, as well as an exhaust port of the fourth exhaust channel. The cross-sectional shape of each section is designed as a rounded rectangle. Table 3 shows the dimensional parameters of the exhaust channel structure described in this comparative example, where L is the length of each segment of the exhaust channel, a is the length of the rectangular cross-section of each segment of the exhaust channel, b is the width of the rectangular cross-section of each segment of the exhaust channel, r is the equivalent radius of the cross-section corresponding to the rectangular cross-section of each segment of the exhaust channel, and S is the cross-sectional area of ​​each segment of the exhaust channel.

[0060] The fourth exhaust duct 7 includes a fourth exhaust duct inlet, a ninth exhaust duct section 71, a sixth exhaust duct transition section 72, a tenth exhaust duct section 73, a seventh exhaust duct transition section 74, an eleventh exhaust duct section 75, and a fourth exhaust duct outlet.

[0061] The fifth exhaust duct 8 includes the fifth exhaust duct inlet, the twelfth exhaust duct section 81, the eighth exhaust duct transition section 82, and the thirteenth exhaust duct section 83.

[0062] The ninth exhaust duct section 71 has a length L71 of 75 mm, a cross-sectional length a71 of 10 mm, a cross-sectional width b71 of 5 mm, an equivalent radius r71 of 3.99 mm, and a cross-sectional area S71 of 50 mm². 2 The tenth exhaust duct section 73 has a length L73 of 75mm, a cross-sectional length a73 of 10mm, a cross-sectional width b73 of 5mm, an equivalent radius r73 of 3.99mm, and a cross-sectional area S73 of 50mm². 2 The twelfth exhaust duct section 81 has a length L81 of 75mm, a cross-sectional length a81 of 10mm, a cross-sectional width b81 of 5mm, an equivalent radius r81 of 3.99mm, and a cross-sectional area S81 of 50mm². 2 The thirteenth exhaust duct section 83 has a length L83 of 75mm, a cross-sectional length a83 of 10mm, a cross-sectional width b83 of 5mm, an equivalent radius r83 of 3.99mm, and a cross-sectional area S83 of 50mm². 2 The eleventh exhaust duct section 75 has a length L75 of 100mm, a cross-sectional length a75 of 20mm, a cross-sectional width b75 of 5mm, an equivalent radius r75 of 5.64mm, and a cross-sectional area S75 of 100mm². 2 The cross-sectional areas S71 of the ninth exhaust duct section 71, S73 of the tenth exhaust duct section 73, S75 of the eleventh exhaust duct section 75, S81 of the twelfth exhaust duct section 81, and S83 of the thirteenth exhaust duct section 83 satisfy the following relationship: (S71+S81):(S73+S83):S75 = 1:1:1. The longitudinal sections of the sixth exhaust duct transition section 72 and the eighth exhaust duct transition section 82 are both tapered structures with a larger outer diameter and a smaller inner diameter, with a taper of 75°. The longitudinal section of the seventh exhaust duct transition section 74 is a right-angled structure with a diagonal line, with a slope of 75°.

[0063] Table 3 shows the dimensional parameters of the vacuum die-casting mold (3) in Comparative Example 2.

[0064] serial number 71 73 81 83 75 a, mm 10 10 10 10 20 b, mm 5 5 5 5 5 r, mm 3.99 3.99 3.99 3.99 5.64 L, mm 75 75 75 75 75 <![CDATA[S,mm 2 ]]> 50 50 50 50 100

[0065] The ninth exhaust channel section 71 and the twelfth exhaust channel section 81 are connected to the die-casting cavity 2, and the eleventh exhaust channel section 75 is connected to the vacuum shut-off valve piston 6. Before die-casting, the gas in the material cake 1 and the die-casting cavity 2 is removed through the fourth exhaust channel 7 and the fifth exhaust channel 8. When the required vacuum level is reached, the vacuum shut-off valve piston 6 closes and stops the evacuation.

[0066] The cold injection and evacuation process of a die-casting cavity was simulated using Fluent software. The initial gas pressure inside the cavity was 101325 Pa. The gas pressure variation curve of the cavity over time in this comparative example was obtained through numerical simulation, as shown below. Figure 4As shown in the figure, the gas pressure curve results indicate that the exhaust duct cavity pressure drops more slowly and the exhaust efficiency is lower when using this comparative design.

[0067] Example 2

[0068] like Figure 3 As shown, this embodiment designs a vacuum die-casting mold (4). The vacuum die-casting mold (4) in this embodiment is the same as the exhaust channel structure designed in Comparative Example 2, but the size parameters are different. The specific size parameters are shown in Table 4 below.

[0069] The vacuum die-casting mold (4) includes a fourth exhaust channel 7 and a fifth exhaust channel 8 symmetrically arranged. The fourth exhaust channel 7 and the fifth exhaust channel 8 share a seventh exhaust channel transition section 74, an eleventh exhaust channel section 75, and a fourth exhaust channel exhaust port. The fourth exhaust channel 7 includes a first exhaust channel inlet, a ninth exhaust channel section 71, a sixth exhaust channel transition section 72, a tenth exhaust channel section 73, a seventh exhaust channel transition section 74, an eleventh exhaust channel section 75, and a fourth exhaust channel exhaust port.

[0070] The fifth exhaust duct 8 includes the fifth exhaust duct inlet, the twelfth exhaust duct section 81, the eighth exhaust duct transition section 82, and the thirteenth exhaust duct section 83.

[0071] The ninth exhaust duct section 71 has a length L71 of 75 mm, a cross-sectional length a71 of 10 mm, a cross-sectional width b71 of 5 mm, an equivalent radius r71 of 3.99 mm, and a cross-sectional area S71 of 50 mm². 2 The tenth exhaust duct section 73 has a length L73 of 85mm, a cross-sectional length a73 of 15mm, a cross-sectional width b73 of 5mm, an equivalent radius r73 of 4.89mm, and a cross-sectional area S73 of 75mm². 2 The twelfth exhaust duct section 81 has a length L81 of 75mm, a cross-sectional length a81 of 10mm, a cross-sectional width b81 of 5mm, an equivalent radius r81 of 3.99mm, and a cross-sectional area S81 of 50mm². 2 The thirteenth exhaust duct section 83 has a length L83 of 85mm, a cross-sectional length a83 of 15mm, a cross-sectional width b83 of 5mm, an equivalent radius r83 of 4.89mm, and a cross-sectional area S83 of 75mm². 2 .

[0072] The eleventh exhaust duct section 75 has a length L75 of 100mm, a cross-sectional length a75 of 40mm, a cross-sectional width b75 of 5mm, an equivalent radius r75 of 7.97mm, and a cross-sectional area S75 of 200mm². 2The cross-sectional areas S71 of the ninth exhaust duct section 71, S73 of the tenth exhaust duct section 73, S75 of the eleventh exhaust duct section 75, S81 of the twelfth exhaust duct section 81, and S83 of the thirteenth exhaust duct section 83 satisfy the following relationship: (S71+S81):(S73+S83):S75 = 1:1.5:2. The longitudinal sections of the sixth exhaust duct transition section 72 and the eighth exhaust duct transition section 82 are both tapered structures with a larger outer diameter and a smaller inner diameter, with a taper of 45°. The longitudinal section of the seventh exhaust duct transition section 74 is a right-angled structure with a diagonal line, with a slope of 45°.

[0073] Table 4 shows the dimensional parameters of the vacuum die-casting mold (4) in Example 2.

[0074] serial number 71 73 81 83 75 a, mm 10 15 10 15 40 b, mm 5 5 5 5 5 r, mm 3.99 4.89 3.99 4.89 7.97 L, mm 75 85 75 85 100 <![CDATA[S,mm 2 ]]> 50 75 50 75 200

[0075] Based on the Fluent software simulation of the cold injection evacuation process in the die-casting cavity, the initial gas pressure inside the cavity was 101325 Pa. The comparative vacuum die-casting mold (3) and vacuum die-casting mold (4) obtained through numerical simulation showed the gas pressure change curves in the cavity over time, as follows: Figure 4 As shown in the figure. From the gas pressure curve results, it can be seen that the gas pressure in the cavity of the optimized and improved exhaust channel in Example 2 decreases significantly faster than that of the vacuum die-casting mold (3) described in Comparative Example 2 under the same evacuation time, thus improving the exhaust efficiency.

[0076] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An exhaust duct structure, characterized in that, It includes an air inlet, an exhaust duct, and an exhaust outlet in sequence; the exhaust duct includes at least two exhaust duct segments and at least one exhaust duct transition segment, the at least two exhaust duct segments are arranged at intervals, and any two adjacent exhaust duct segments are connected by an exhaust duct transition segment, the ratio of the length of the exhaust duct segment to its equivalent cross-sectional radius is 5 to 30, and the ratio of the cross-sectional area of ​​any one exhaust duct segment to the cross-sectional area of ​​the next exhaust duct segment is 1.2 to 1.

6.

2. The exhaust duct structure according to claim 1, characterized in that, The length of the exhaust duct section is less than 100mm.

3. The exhaust duct structure according to claim 1, characterized in that, The longitudinal section of the exhaust duct transition section is a tapered structure with a taper of 15 to 45°.

4. The exhaust duct structure according to claim 1, characterized in that, The exhaust duct consists of an exhaust duct section, an exhaust duct transition section, and an exhaust duct section, which are repeated in a cycle according to the required length of the exhaust duct.

5. The exhaust duct structure according to claim 1, characterized in that, The cross-sectional shape of the exhaust duct is circular or rectangular with rounded corners.

6. A vacuum die-casting mold, characterized in that, It includes a material cake, a die-casting cavity, a vacuum shut-off valve piston, and an exhaust duct structure as described in any one of claims 1 to 5; Before die casting, the gas in the die cake and die casting cavity is removed through the exhaust channel structure. When the required vacuum level is reached, the vacuum shut-off valve piston is closed to complete the exhaust process. During the vacuum die casting process, the air inlet of the exhaust channel structure is connected to the die casting cavity, and the exhaust outlet of the exhaust channel structure is connected to the vacuum shut-off valve piston.

7. The vacuum die-casting mold according to claim 6, characterized in that, The exhaust duct structure includes three exhaust ducts, namely a first exhaust duct, a second exhaust duct, and a third exhaust duct. The first exhaust duct, the second exhaust duct, and the third exhaust duct are connected in parallel, and the first exhaust duct and the third exhaust duct are arranged symmetrically.

8. The vacuum die-casting mold according to claim 7, characterized in that, The first exhaust duct includes a first exhaust duct inlet, a first exhaust duct section, a first exhaust duct transition section, a second exhaust duct section, a second exhaust duct transition section, a third exhaust duct section, and a first exhaust duct outlet; The second exhaust duct includes a second exhaust section inlet, a fourth exhaust section, a third exhaust section transition section, a fifth exhaust section, and a second exhaust duct outlet; The third exhaust duct includes the third exhaust duct inlet, the sixth exhaust duct section, the fourth exhaust duct transition section, the seventh exhaust duct section, the fifth exhaust duct transition section, the eighth exhaust duct section, and the third exhaust duct outlet.

9. The vacuum die-casting mold according to claim 6, characterized in that, The exhaust duct structure includes a fourth exhaust duct and a fifth exhaust duct arranged symmetrically. The fourth exhaust duct and the fifth exhaust duct have a seventh exhaust duct transition section, an eleventh exhaust duct section, and an exhaust port of the fourth exhaust duct.

10. The vacuum die-casting mold according to claim 9, characterized in that, The fourth exhaust duct includes the fourth exhaust duct inlet, the ninth exhaust duct section, the sixth exhaust duct transition section, the tenth exhaust duct section, the seventh exhaust duct transition section, and the eleventh exhaust duct section, as well as the fourth exhaust duct outlet. The fifth exhaust duct includes the fifth exhaust duct inlet, the twelfth exhaust duct section, the eighth exhaust duct transition section, and the thirteenth exhaust duct section.

Images