Gas-assisted forming die for automobile door panel

Abstract

The utility model relates to the technical field of automobile door panel production dies, in particular to an automobile door panel gas-assisted forming die which comprises a lower die and an upper die buckled above the lower die, a lower die cavity is formed in the top of the lower die, and an upper die core is installed at the bottom of the upper die. Due to the pressure difference, the cooling liquid which firstly enters the lower cooling cavity is fully filled in the lower cooling cavity, then enters the upper cooling cavity and finally fully fills the whole upper cooling cavity, so that the cooling liquid is fully contacted with the injection mold cavity, the cooling efficiency of the whole mold is improved, and the cooling liquid is finally discharged from the cooling liquid outlet pipe; the cooling liquid outlet pipe is communicated with the cooling channel, the cooling liquid outlet pipe is communicated with the upper cooling cavity, the cooling channel surrounds the gas injection pipe, high-pressure inert gas entering the mold cavity can be cooled, and therefore the cooling efficiency of the whole mold is further improved from inside to outside.

Description

Technical Field

[0001] This utility model relates to the field of automotive door panel production mold technology, specifically to an automotive door panel gas-assisted molding mold. Background Technology

[0002] Gas-assisted injection molding molds for automotive door panels are advanced injection molding equipment, mainly used to produce lightweight, high-strength, low-warpage automotive interior parts (such as door panels).

[0003] During the injection molding process, a portion of the molten plastic (approximately 70% to 90%) is first injected into the mold cavity. Then, high-pressure inert gas (usually nitrogen) is injected through the air inlet in the mold, pushing the molten material to fill the cavity and form a hollow structure.

[0004] As shown in the patent authorized announcement number CN218111398U, the traditional mold adopts a design in which the coolant flows unidirectionally from the upper mold cavity to the lower mold cavity. Due to the short flow path, the coolant is easily discharged before it fully contacts the mold cavity. In particular, the cooling of the thick-walled area of ​​the door panel is insufficient, which can cause shrinkage marks or warping.

[0005] The heat carried by high-pressure nitrogen injection will locally increase the temperature of the mold cavity, and the existing mold lacks active cooling of the gas channel, which further aggravates the uneven cooling.

[0006] Inefficient cooling systems force longer pressure holding and cooling times, increasing production costs;

[0007] Therefore, there is an urgent need for an air-assisted molding die that can achieve uniform and efficient cooling in order to improve the production quality and efficiency of automotive door panels. Utility Model Content

[0008] In view of the above-mentioned shortcomings of the existing technology, the present invention provides an air-assisted molding die for automobile door panels, which can effectively solve the problems mentioned in the background art.

[0009] To achieve the above objectives, this utility model provides the following technical solution:

[0010] This utility model provides an air-assisted molding die for an automotive door panel, including a lower die and an upper die fastened to the lower die. The lower die has a lower mold cavity at its top, and an upper mold core is installed at the bottom of the upper die, extending into the lower mold cavity. A cooling assembly is provided: a coolant inlet pipe is installed at the bottom of the lower die, a lower cooling cavity is formed around the lower mold cavity at the top of the lower die, and an upper cooling cavity is formed around the upper mold core at the bottom of the upper die. The lower cooling cavity is connected to both the coolant inlet pipe and the upper cooling cavity. A connector is fixedly installed at the top of the upper die. An air injection port connected to the lower mold cavity is opened at the top and bottom of the connector, penetrating through the connector. A cooling channel is also formed around the air injection port at the bottom of the connector, connected to the upper cooling cavity. A coolant outlet pipe connected to the cooling channel is installed on the outer wall of the connector.

[0011] Furthermore, guide pillars are vertically fixed at the four corners of the top of the lower mold, and two symmetrically distributed bases are installed at the bottom of the lower mold.

[0012] Furthermore, an injection tube is installed on the top of the upper mold, and guide holes are provided through the four corners of the upper mold.

[0013] Furthermore, the four guide pillars are respectively inserted into the corresponding guide holes, and handles are vertically fixed at both ends of the upper mold.

[0014] Furthermore, the top of the upper mold core has an injection port that communicates with the injection tube through the bottom.

[0015] Furthermore, the top of the upper mold core is provided with several air inlets that are connected to the air injection port through the bottom.

[0016] The technical solution provided by this utility model has the following advantages compared with the known prior art:

[0017] First, through the series cooling path of lower cooling chamber → upper cooling chamber → cooling channel, the pressure difference ensures that the coolant fills each cavity in sequence, avoids short-circuit flow, and increases the surface contact rate of the mold cavity by more than 30%. The cooling channel is designed to surround the gas injection port, which simultaneously reduces the temperature of the high-pressure gas, achieving bidirectional cooling from the inside out and reducing the impact of gas thermal effects on the product.

[0018] Secondly, sufficient contact between the coolant and the mold cavity can shorten the cooling time by about 20%, significantly reducing the production cycle. By monitoring the coolant outlet temperature and dynamically adjusting the flow rate, energy consumption can be further optimized. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0021] Figure 2 This is a schematic diagram of the lower mold structure of this utility model;

[0022] Figure 3 This is a schematic diagram of the upper mold structure of this utility model;

[0023] Figure 4 This is a front sectional view of the connector of this utility model.

[0024] The labels in the diagram represent:

[0025] 1. Lower mold; 11. Lower mold cavity; 12. Lower cooling cavity; 13. Guide pillars;

[0026] 2. Upper mold; 21. Injection tube; 22. Upper cooling cavity; 23. Guide hole; 24. Handle;

[0027] 3. Upper mold core; 31. Injection port; 32. Air inlet;

[0028] 4. Connector; 41. Air inlet; 42. Cooling channel; 43. Coolant outlet pipe. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0030] The present invention will be further described below with reference to the embodiments. Example

[0031] Reference Figure 1-4This is the first embodiment of the present invention, which discloses an air-assisted molding die for an automobile door panel, including a lower die 1 and an upper die 2 fastened above the lower die 1. The surface of the upper die 2 is also provided with an exhaust port that communicates with the cavity. An exhaust valve is installed in the exhaust port. The exhaust valve is spring-loaded and has an opening pressure of 0.2 MPa. It is located at the edge of the parting surface of the upper die 2. The top of the lower die 1 is provided with a lower mold cavity 11. The bottom of the upper die 2 is provided with an upper mold core 3. The upper mold core 3 extends into the lower mold cavity 11. The bottom of the lower die 1 is provided with a coolant inlet pipe. The top of the lower die 1 is provided with a lower cooling cavity 12 surrounding the lower mold cavity 11. The bottom of the lower cooling cavity 12 is provided with an inclined guide groove to ensure that the coolant flows without dead corners.

[0032] The upper mold 2 has an upper cooling cavity 22 at the bottom that surrounds the upper mold core 3. The lower cooling cavity 12 is connected to both the coolant inlet pipe and the upper cooling cavity 22. The connector 4 is fixedly installed on the top of the upper mold 2. The top of the connector 4 has an air injection port 41 that is connected to the lower mold cavity 11 through the bottom. The bottom of the connector 4 also has a cooling channel 42 that surrounds the air injection port 41. The distance between the cooling channel 42 and the air injection port 41 is 5-8mm to ensure efficient heat exchange. The cooling channel 42 is connected to the upper cooling cavity 22. The outer wall of the connector 4 is equipped with a coolant outlet pipe 43 that is connected to the cooling channel 42. A PT100 temperature sensor is installed on the coolant outlet pipe 43. The PT100 temperature sensor is installed on the side wall of the coolant outlet pipe 43 through a threaded interface (M6×1) and connected to an external PLC controller to adjust the flow rate.

[0033] Coolant (water-based solution, temperature 20°C) is injected from the inlet pipe at the bottom of the lower mold 1 at a flow rate of 15 L / min, and the flow path is as follows:

[0034] First, fill the lower cooling chamber 12 (approximately 1.2L in volume, taking 3 seconds);

[0035] It then enters the upper cooling chamber 22 (approximately 0.8L in volume, taking 2 seconds);

[0036] Finally, the coolant flows through the cooling channel 42 of the connector 4 (surrounding the air inlet 41, 150 mm in length and 8 mm in diameter) and is discharged from the coolant outlet pipe 43.

[0037] The flow rate is dynamically adjusted by monitoring the coolant outlet temperature using a temperature sensor. If the outlet temperature is greater than 35°C, the flow rate is increased to 20L / min.

[0038] Demolding and post-processing

[0039] After a total cooling time of 40 seconds, the mold is opened, and the air ejector (not shown in the figure) pushes the door panel product out of the lower mold cavity 11.

[0040] Trim the remaining material stalk (diameter ≤ 1 mm) at the air inlet (32) and deburr the edges of the door panel. Example

[0041] Reference Figure 1-4 This is the second embodiment of the present invention. This embodiment differs from the first embodiment in that: guide posts 13 are vertically fixedly installed at the four corners of the top of the lower mold 1; two symmetrically distributed bases are installed at the bottom of the lower mold 1; an injection tube 21 is installed at the top of the upper mold 2; guide holes 23 are provided through the four corners of the upper mold 2; the four guide posts 13 are respectively inserted into the corresponding guide holes 23; the top of the guide posts 13 is designed with a reduced diameter to facilitate insertion into the corresponding guide holes 23. Inside the mold 3, handles 24 are vertically fixed at both ends of the upper mold 2. The handles 24 facilitate the separation and closing of the upper mold 2 and the lower mold 1. The top of the upper mold core 3 is provided with an injection port 31 that is connected to the injection tube 21. The top of the upper mold core 3 is provided with several air inlets 32 that are connected to the air inlet 41. The air inlets 32 are evenly distributed along the door panel reinforcing ribs with a spacing of 80-100mm. A certain amount of molten plastic liquid is injected into the cavity through the injection tube 21 and the injection port 31.

[0042] The remaining structure is the same as that in Example 1.

[0043] The working process of this utility model is as follows:

[0044] First, fix the lower mold 1 onto the injection molding machine worktable using the base, ensuring that the levelness error is ≤0.05mm / m;

[0045] The upper mold 2 and the lower mold 1 are closed by an external hydraulic mechanism, and the guide post 13 is precisely inserted into the guide hole 23. After closing, the gap between the parting surfaces is ≤0.02mm.

[0046] Turn on the mold temperature controller and raise the mold temperature to 60±5°C (for PP material). The preheating time is about 15-20 minutes.

[0047] Ensure alignment with the injection unit and gas-assisted control unit, and connect the high-pressure nitrogen gas (pressure is usually 20~30MPa).

[0048] Next, molten polypropylene (PP, melt temperature 230±10°C) is injected through injection tube 21 and injection port 31. The injection volume is 80% of the cavity volume, and the injection speed is controlled in three stages:

[0049] First stage (initial filling): Low speed (20mm / s) to avoid spray marks;

[0050] Second stage (mid-filling): High speed (80mm / s) ensures rapid filling;

[0051] Third stage (end of filling): Reduce speed to 40mm / s to prevent overflow;

[0052] Injection speed: medium to high speed filling to avoid premature cooling of the melt front;

[0053] Melt temperature: Adjust according to the material (e.g., PP is usually 200~250°C);

[0054] Delay time: 0.5 to 3 seconds after melt injection (to ensure surface curing and prevent gas from penetrating the surface);

[0055] High-pressure nitrogen enters the core of the melt through the air inlet, pushing the molten material to continue filling the cavity and forming a medium-pressure air channel;

[0056] Gas pressure is controlled in stages: initial high pressure for penetration, followed by low pressure maintenance (to prevent gas passage collapse).

[0057] Gas pressure holding: Gas is continuously applied under pressure to compensate for melt contraction until cooling is complete;

[0058] Finally, coolant is continuously injected into the lower cooling chamber 12 through the coolant inlet pipe. After the coolant fills the entire lower cooling chamber 12, it enters the upper cooling chamber 22. After the upper cooling chamber 22 is filled, it enters the cooling channel 42 and is finally discharged from the coolant outlet pipe 43. By detecting the temperature of the coolant flowing out of the coolant outlet pipe 43, the power of the coolant delivery pump is controlled to increase or decrease the flow rate of the coolant, so that the product is cooled to the demolding temperature. The time is adjusted according to the wall thickness (usually 20~60 seconds). After cooling, the gas pressure in the cavity is released through the exhaust valve to avoid the product bursting due to residual gas pressure inside when the mold is opened.

[0059] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of this utility model.

Claims

1. A gas-assisted molding die for automotive door panels, characterized in that, The system includes a lower mold (1) and an upper mold (2) that is fastened to the lower mold (1). The lower mold (1) has a lower mold cavity (11) at its top, and an upper mold core (3) is installed at the bottom of the upper mold (2). The upper mold core (3) extends into the lower mold cavity (11). The system also includes: The cooling assembly has a coolant inlet pipe installed at the bottom of the lower mold (1), a lower cooling cavity (12) surrounding the lower mold cavity (11) at the top of the lower mold (1), and an upper cooling cavity (22) surrounding the upper mold core (3) at the bottom of the upper mold (2). The lower cooling cavity (12) is connected to both the coolant inlet pipe and the upper cooling cavity (22). The connector (4) is fixedly installed on the top of the upper mold (2). The top of the connector (4) has an air injection port (41) that communicates with the lower mold cavity (11) through the bottom. The bottom of the connector (4) also has a cooling channel (42) that surrounds the air injection port (41). The cooling channel (42) communicates with the upper cooling cavity (22). The outer wall of the connector (4) is equipped with a coolant outlet pipe (43) that communicates with the cooling channel (42).

2. The automotive door panel gas-assisted molding die according to claim 1, characterized in that, The lower mold (1) has guide columns (13) vertically fixed at the four corners of its top, and two symmetrically distributed bases installed at the bottom of the lower mold (1).

3. The automotive door panel gas-assisted molding die according to claim 2, characterized in that, The top of the upper mold (2) is equipped with an injection tube (21), and guide holes (23) are opened through the four corners of the upper mold (2). The surface of the upper mold (2) is also provided with an exhaust port that communicates with the lower mold cavity, and an exhaust valve is installed in the exhaust port.

4. The automotive door panel gas-assisted molding die according to claim 3, characterized in that, The four guide pillars (13) are respectively inserted into the corresponding guide holes (23) and the upper mold (2) is vertically fixed with handles (24) at both ends.

5. The automotive door panel gas-assisted molding die according to claim 1, characterized in that, The top of the upper mold core (3) is provided with an injection port (31) that is connected to the injection tube (21).

6. The automotive door panel gas-assisted molding die according to claim 1, characterized in that, The top of the upper mold core (3) is provided with several air inlets (32) that are connected to the air injection port (41).

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