Precision mold and gas pressurization hot runner casting molding process

Abstract

The invention relates to a precision mold and a gas pressurization hot runner casting molding process, and belongs to the technical field of precision molds, the precision mold comprises an upper mold and a lower mold, and hot runner assemblies are arranged in the upper mold and the lower mold; four demolding assemblies are distributed at the corners of the periphery of the lower mold in a rectangular shape and are vertically assembled and arranged. According to the precise mold and the gas pressurization hot runner casting molding process, the hot runner assemblies arranged in the upper mold and the lower mold are matched with the gas pressurization system communicating with the upper mold, so that in the injection molding process of the precise mold, the temperature of a plastic melt can be kept uniform, and cold charge lines and weld marks are reduced; and through gas-assisted injection molding, warping and sinking of the injection molded part can be prevented, so that the compactness and the surface quality of the product are greatly improved, and through precise control over the opening and closing height of the mold, it is ensured that demolding of the product is completed at the optimal position, and the idle time for opening and closing of the mold is shortened.

Description

Technical Field

[0001] The invention relates to the technical field of precision moulds, in particular to a precision mould and a gas pressurized hot runner casting process. Background Art

[0002] Precision molds are molds with high precision, high complexity and long life, mainly used to manufacture high-quality, high-performance precision parts. They are widely used in industries such as electronics, automobiles, medical, aerospace and consumer goods to produce plastic parts, metal parts and other products with complex shapes and strict dimensional requirements.

[0003] Precision molds are tools used to shape plastic materials (such as metals, plastics, rubber, etc.). They not only determine the shape of the product, but also have a direct impact on the dimensional tolerance, surface finish and performance of the product. Its characteristics are that both mold manufacturing and product molding require high precision, and the dimensional tolerance is usually controlled at the micron level.

[0004] In actual use, the traditional injection molding process mostly adopts cold runner casting. Although the cold runner casting molding process has low cost, it has some significant disadvantages, especially in precision manufacturing and large-scale production. These disadvantages are mainly concentrated in material waste, low molding efficiency, and limited product quality. That is, the cold runner system will produce a large amount of solidified runner waste (i.e., cooled plastic that has not entered the mold cavity) after each injection. Although these wastes can be recycled and reused, repeated use can easily lead to a decrease in material performance; at the same time, the temperature of the cold runner plastic will be reduced due to the heat transfer effect, which can easily cause the melt fluidity to deteriorate during the injection molding process, affecting the mold cavity filling speed and quality; at the same time, the existing precision molds are not convenient enough when demolding, and are prone to incomplete demolding problems.

[0005] Therefore, considering the injection molding requirements of high precision, high quality and complex structure, a precision mold and gas pressurized hot runner casting molding process are proposed to solve the above problems. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a precision mold and gas pressurized hot runner casting molding process, which introduces high-pressure gas during the molding process and cooperates with the hot runner to accurately control the flow of plastic melt to achieve injection molding of complex shapes and high-quality products.

[0007] To achieve the above object, the present invention provides the following technical solution: a precision mold, comprising an upper mold and a lower mold:

[0008] The upper mold and the lower mold are arranged opposite to each other; the upper mold is detachably assembled on the lower mold, and a cavity for injection molding is formed in both the upper mold and the lower mold;

[0009] The upper mold and the lower mold are both provided with hot runner components;

[0010] The four corners of the lower mold are distributed in a rectangular shape and are vertically assembled with four sets of demoulding components;

[0011] The upper mold is connected to a gas pressurization system.

[0012] Furthermore, the hot runner assembly includes a plurality of hot runner pipelines that are connected to each other, and the plurality of hot runner pipelines are staggered and respectively assembled in the upper mold and the lower mold.

[0013] Furthermore, an injection hole is provided on the upper mold, an injection molding mold core is installed in the lower mold, and the bottom outlet of the injection hole extends to the injection molding mold core and is connected with it; a plurality of hot runner pipelines are arranged around the injection molding mold core.

[0014] Furthermore, both ends of the plurality of hot runner pipelines are respectively connected with hot runner nozzles, and the hot runner nozzles are assembled on the upper mold and the lower mold and extend to the outside of the upper mold and the lower mold.

[0015] Furthermore, the demoulding assembly comprises a lower cylinder arranged on the lower mold, and an upper cylinder is slidably arranged in the lower cylinder.

[0016] Furthermore, two inner ear seats are symmetrically arranged on the inner wall of the upper tube, through holes are opened on the two inner ear seats, and the outer wall ends of the inner ear seats have rounded corners.

[0017] Furthermore, a reciprocating motor is installed in the lower cylinder, and the output end of the reciprocating motor is rotatably connected to a screw rod, and a sliding shaft seat is meshed on the outside of the screw rod.

[0018] Furthermore, a limit seat is provided on the outside of the sliding shaft seat, and two ear plates are integrally provided on the outside of the limit seat. One side of the two ear plates is connected to the inner wall of the upper cylinder, and two side limit rods are installed on the outer wall of the reciprocating motor. The two side limit rods respectively correspond to one of the inner ear seats and extend through the inner ear seats.

[0019] On this basis, the present invention also provides a gas pressurized hot runner casting molding process, which comprises the following steps:

[0020] S1. Mold preparation and preheating: Ensure that the mold cavity, injection hole and hot runner assembly are free of impurities and residues, then start the hot runner assembly and heat the hot runner assembly to the set temperature, which is usually slightly higher than the melting temperature of the material to ensure that the melt can maintain uniform fluidity before entering the mold cavity and ensure that the gas booster system works properly.

[0021] S2, plastic melting and injection molding preparation: add the injection molding material into the injection molding machine hopper and plasticize it to ensure that the melt reaches a uniform molten state, set the injection pressure, speed and temperature to ensure that the material can flow smoothly from the injection hole into the injection molding mold core; heat the hot runner components in different areas to ensure that the melt temperature in the runner is evenly distributed to avoid flow instability caused by local cooling;

[0022] S3, melt injection and cavity filling; start the injection machine, and inject the molten plastic into the injection molding mold through the injection hole. At this time, the hot runner component keeps the material in a molten state during the whole process, and no cold material is generated in the runner. Subsequently, when the melt fills the injection molding mold to a certain extent, such as %-%, high-pressure gas is introduced into the injection hole, so that the high-pressure gas enters the melt through the injection hole, and the high-pressure gas pushes the melt to continue to flow and fill the remaining injection molding mold.

[0023] S4. The gas is continuously pressurized to prevent the melt from flowing back and to compensate for the volume shrinkage of the melt during cooling. The melt in the injection molding mold is then cooled and solidified, and the gas pressure is kept constant to ensure the dimensional accuracy and surface quality of the product. After cooling, the high-pressure gas in the injection molding mold is gradually released. The gas can be recycled or safely discharged through the recovery system. Finally, four sets of demolding components are used to complete the demolding of the upper and lower molds.

[0024] Compared with the prior art, the technical solution of this application has the following beneficial effects:

[0025] The precision mold and gas-pressurized hot runner casting molding process, through the hot runner components arranged in the upper mold and the lower mold, cooperate with the gas pressurization system connected to the upper mold, so that the precision mold of the present application can maintain the uniform temperature of the plastic melt during the injection molding process, reduce the occurrence of cold material lines and weld marks, thereby reducing uneven surface texture or flow marks of the plastic part, and through gas-assisted injection molding, it can also prevent the injection molded parts from warping and sinking, thereby greatly improving the density and surface quality of the product.

[0026] The precision mold and gas-pressurized hot runner casting molding process, through the movement coordination of four groups of demolding components arranged in the lower mold, enables the demolding components with adjustable height to quickly realize the demolding process between the upper mold and the lower mold; during use, by accurately controlling the mold opening and closing height, it is ensured that the product is demolded at the best position, reducing the idle time of mold opening and closing, and preventing the mold from getting stuck or mold interference due to height error during the demolding process, thereby reducing the downtime required for adjusting the mold height. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the overall installation structure of the present invention;

[0028] Figure 2It is a schematic diagram of the overall installation structure of the hot runner assembly of the present invention;

[0029] Figure 3 This is a schematic diagram of the overall installation structure of the demoulding component of the present invention;

[0030] Figure 4 It is a schematic structural diagram of the gas pressurized hot runner casting molding process steps of the present invention.

[0031] In the figure: 1. upper mold; 2. lower mold; 3. injection hole; 31. injection molding mold core; 4. hot runner assembly; 41. hot runner nozzle; 42. hot runner pipeline; 5. demoulding assembly; 51. lower cylinder; 52. reciprocating motor; 53. screw; 54. sliding shaft seat; 55. limit seat; 56. ear plate; 57. side limit rod; 58. upper cylinder; 59. inner ear seat. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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 are within the scope of protection of the present invention.

[0033] See also Figure 1-4 , a precision mold in this embodiment includes an upper mold 1 and a lower mold 2:

[0034] The upper mold 1 and the lower mold 2 are arranged opposite to each other; the upper mold 1 is detachably assembled on the lower mold 2, and a cavity for injection molding is formed in both the upper mold 1 and the lower mold 2;

[0035] A hot runner assembly 4 is provided in both the upper mold 1 and the lower mold 2;

[0036] Four sets of demoulding components 5 are arranged in a rectangular shape at the four corners of the lower mold 2 and are vertically assembled;

[0037] The upper mold 1 is connected to a gas pressurization system.

[0038] In this embodiment, by setting the hot runner assembly 4 in the upper mold 1 and the lower mold 2, and cooperating with the gas booster system connected to the upper mold 1, the precision mold of the present application can maintain the uniform temperature of the plastic melt during the injection molding process, reduce the occurrence of cold material lines and weld marks, thereby reducing the uneven texture or flow marks on the surface of the plastic part, and through gas-assisted injection molding, it can also prevent the injection molded parts from warping and sinking, thereby greatly improving the density and surface quality of the product.

[0039] Furthermore, by the movement coordination of the four groups of demolding components 5 arranged in the lower mold 2, the demolding components 5 with adjustable height can quickly realize the demolding process between the upper mold 1 and the lower mold 2; during use, by accurately controlling the opening and closing height of the mold, it is ensured that the product is demolded in the best position, reducing the idle time of mold opening and closing, and preventing the mold from getting stuck or interfering with the mold due to height errors during the demolding process, thereby reducing the downtime required for adjusting the mold height.

[0040] It should be noted that the gas boosting system introduced into the upper mold 1 is a prior art and can be implemented through simple programming by technicians in this field. It is common knowledge in this field and is only used without modification. Therefore, the control method and circuit connection will not be described in detail.

[0041] See also Figure 1-2 In order to ensure that the plastic is always in a molten state, thereby ensuring the fluidity and stability of the plastic during the injection molding process, the hot runner assembly 4 in this embodiment includes a plurality of hot runner pipes 42 that are connected and arranged, and the plurality of hot runner pipes 42 are staggered and respectively assembled in the upper mold 1 and the lower mold 2; an injection hole 3 is arranged on the upper mold 1, and an injection molding mold core 31 is assembled in the lower mold 2, and the bottom outlet of the injection hole 3 extends to the injection molding mold core 31 and is connected with it; a plurality of hot runner pipes 42 are arranged around the injection molding mold core 31; hot runner nozzles 41 are respectively connected and arranged at both ends of the plurality of hot runner pipes 42, and the hot runner nozzles 41 are assembled on the upper mold 1 and the lower mold 2 and extend to the outside of the upper mold 1 and the lower mold 2.

[0042] In this embodiment, when the hot runner assembly 4 is started, the several hot runner pipes 42 arranged in the upper mold 1 and the lower mold 2 can be electrically heated to generate high temperature. The hot runner pipes 42 arranged at this time can ensure that the temperature of each area of ​​the hot runner is uniform after generating high temperature, thereby preventing the plastic melt from cooling down too quickly and causing insufficient filling. At the same time, the high temperature of the hot runner pipes 42 can ensure the fluidity and stability of the plastic during the injection molding process.

[0043] Furthermore, the provided hot runner pipe port 41 can be used to connect to an external spring-type heating wire, so as to heat and regulate the hot runner pipeline 42 .

[0044] Furthermore, by introducing a gas boosting system on the upper mold 1, when the melt fills the injection molding mold core 31 to a certain extent, such as 80%-90%, high-pressure gas is introduced into the injection hole 3, so that the high-pressure gas enters the melt through the injection hole 3. At this time, the high-pressure gas will push the plastic melt to continue to flow until the remaining injection molding mold core 31 is filled. At the same time, during this period, the high-pressure gas continues to apply boosting, which can not only prevent the plastic melt from flowing back, but also compensate for the volume shrinkage during the cooling of the melt, so that the plastic is subjected to uniform pressure in the injection hole 3, thereby improving the density and surface quality of the product and ensuring the dimensional accuracy of the product.

[0045] It should be noted that, after the plastic melt is cooled in the injection molding mold core 31 , the high-pressure gas in the injection molding mold core 31 can be gradually released, and the gas can be recycled or safely discharged through a recovery system.

[0046] It is further explained that the gas pressurized hot runner casting molding process of the present application optimizes the molding process by combining hot runner technology with gas-assisted injection molding, and is particularly suitable for high-end precision mold production. The process steps cover mold preheating, melt injection, gas pressurization, cooling and demoulding, thereby effectively ensuring product quality and production efficiency.

[0047] See also Figure 3 In order to quickly demould the upper mold 1 and the lower mold 2, the demoulding assembly 5 in this embodiment includes a lower cylinder 51 arranged on the lower mold 2, an upper cylinder 58 is slidably arranged in the lower cylinder 51, two inner ear seats 59 are symmetrically arranged on the inner wall of the upper cylinder 58, through holes are opened on the two inner ear seats 59, and the outer wall ends of the inner ear seats 59 have a rounded corner setting, a reciprocating motor 52 is assembled in the lower cylinder 51, and the output end of the reciprocating motor 52 is rotatably connected with a screw rod 53, a sliding shaft seat 54 is meshed on the outside of the screw rod 53, and a limit seat 55 is sleeved on the outside of the sliding shaft seat 54, and two ear plates 56 are integrally arranged on the outside of the limit seat 55, one side of the two ear plates 56 is connected to the inner wall of the upper cylinder 58, and two side limit rods 57 are installed on the outer wall of the reciprocating motor 52, and the two side limit rods 57 respectively correspond to one of the inner ear seats 59 and extend through the inner ear seat 59.

[0048] In this embodiment, the user assembles the upper mold 1 on the four groups of demolding assemblies 5, and connects the upper mold 1 with the four groups of upper cylinders 58. When the upper mold 1 needs to be demolded, the reciprocating motor 52 is connected to a power source. When the reciprocating motor 52 drives the screw rod 53 to rotate, the side limit rod 57 limits the inner ear seat 59, and the ear plate 56 is connected to the inner wall of the upper cylinder 58, so that the upper cylinder 58 can be lifted and lowered in a straight line along the stroke range of the screw rod 53, and then realize the linear sliding lifting and lowering in the lower cylinder 51. The user can adjust the spacing between the upper mold 1 and the lower mold 2 at different heights by controlling the displacement stroke of the upper cylinder 58, so that the lower mold 2 can perform demolding operations at different heights.

[0049] It should be noted that the reciprocating motor 52 is an existing structure, its power connection method is an existing technology, and the control circuit can be realized by simple programming by technicians in this field, which belongs to the common knowledge in this field. It is only used without modification, so the control method and circuit connection are not described in detail.

[0050] On this basis, the present invention also provides a gas pressurized hot runner casting molding process, which comprises the following steps:

[0051] S1. Mold preparation and preheating: Ensure that the mold cavity, injection hole 3 and hot runner assembly 4 are free of impurities and residues, then start the hot runner assembly 4, heat the hot runner assembly 4 to the set temperature, which is usually slightly higher than the melting temperature of the material, to ensure that the melt can maintain uniform fluidity before entering the mold cavity, and ensure that the gas booster system works normally.

[0052] S2, plastic melting and injection molding preparation; adding the injection molding material to the injection molding machine hopper and plasticizing it to ensure that the melt reaches a uniform molten state, setting the injection pressure, speed and temperature to ensure that the material can smoothly flow from the injection hole 3 into the injection molding mold core 31; heating the hot runner assembly 4 in different zones to ensure that the melt temperature in the runner is evenly distributed to avoid flow instability caused by local cooling;

[0053] S3, melt injection and mold cavity filling; start the injection machine, and inject the molten plastic into the injection molding core 31 through the injection hole 3. At this time, the hot runner assembly 4 keeps the material in a molten state during the whole process, and no cold material is generated in the runner. Subsequently, when the melt fills the injection molding core 31 to a certain extent, such as 80%-90%, high-pressure gas is introduced into the injection hole 3, so that the high-pressure gas enters the melt through the injection hole 3, and the high-pressure gas pushes the melt to continue to flow, filling the remaining injection molding core 31.

[0054] S4, the gas is continuously pressurized to prevent the melt from flowing back and to compensate for the volume shrinkage of the melt during cooling. The melt in the injection molding mold core 31 is then cooled and solidified, and the gas pressure is kept constant to ensure the dimensional accuracy and surface quality of the product. After cooling is completed, the high-pressure gas in the injection molding mold core 31 is gradually released. The gas can be recycled or safely discharged through a recovery system. Finally, four sets of demolding components 5 are used to complete the demolding of the upper mold 1 and the lower mold 2.

[0055] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A precision mold, comprising an upper mold (1) and a lower mold (2), characterized in that: The upper mold (1) and the lower mold (2) are arranged opposite to each other; the upper mold (1) is detachably mounted on the lower mold (2), and a cavity for injection molding is formed in both the upper mold (1) and the lower mold (2); A hot runner assembly (4) is disposed in both the upper mold (1) and the lower mold (2); The four corners of the lower mold (2) are distributed in a rectangular shape and vertically assembled with four groups of demoulding components (5); The upper mold (1) is connected to a gas pressurization system.

2. The precision mold according to claim 1, characterized in that: The hot runner assembly (4) comprises a plurality of hot runner pipelines (42) which are arranged in communication with each other. The plurality of hot runner pipelines (42) are arranged in a staggered manner and are respectively assembled in the upper mold (1) and the lower mold (2).

3. The precision mold according to claim 2, characterized in that: The upper mold (1) is provided with an injection hole (3), the lower mold (2) is provided with an injection molding mold core (31), the bottom outlet of the injection hole (3) extends to the injection molding mold core (31) and is connected thereto; a plurality of hot runner pipelines (42) are arranged around the injection molding mold core (31).

4. The precision mold according to claim 2, characterized in that: Both ends of the plurality of hot runner pipelines (42) are respectively connected to be provided with hot runner pipe openings (41); the hot runner pipe openings (41) are mounted on the upper mold (1) and the lower mold (2) and extend to the outside of the upper mold (1) and the lower mold (2).

5. The precision mold according to claim 1, characterized in that: The demoulding assembly (5) comprises a lower cylinder (51) arranged on the lower mold (2), and an upper cylinder (58) is slidably arranged inside the lower cylinder (51).

6. The precision mold according to claim 5, characterized in that: Two inner ear seats (59) are symmetrically arranged on the inner wall of the upper tube (58), and through holes are opened on the two inner ear seats (59). The outer wall ends of the inner ear seats (59) have rounded corners.

7. The precision mold according to claim 5, characterized in that: A reciprocating motor (52) is installed inside the lower cylinder (51), and an output end of the reciprocating motor (52) is rotatably connected to a screw rod (53), and a sliding shaft seat (54) is meshedly provided on the outside of the screw rod (53).

8. The precision mold according to claim 7, characterized in that: The sliding shaft seat (54) is sleeved with a limit seat (55) on the outside, and two ear plates (56) are integrally provided on the outside of the limit seat (55), and one side of the two ear plates (56) is connected to the inner wall of the upper cylinder (58). The outer wall of the reciprocating motor (52) is installed with two side limit rods (57), and the two side limit rods (57) respectively correspond to one of the inner ear seats (59) and extend through the inner ear seat (59).

9. A gas pressurized hot runner casting process, which is implemented using the precision mold described in any one of 1 to 8 above, characterized in that: It contains the following steps: S1. Mold preparation and preheating: Ensure that the mold cavity, injection hole (3) and hot runner assembly (4) are free of impurities and residues, then start the hot runner assembly (4) and heat the hot runner assembly (4) to a set temperature, which is usually slightly higher than the melting temperature of the material, to ensure that the melt can maintain uniform fluidity before entering the mold cavity and to ensure that the gas booster system works properly. S2, plastic melting and injection molding preparation; adding the injection molding material into the injection molding machine hopper and plasticizing it to ensure that the melt reaches a uniform molten state, setting the injection pressure, speed and temperature to ensure that the material can smoothly flow from the injection hole (3) into the injection molding mold core (31); heating the hot runner assembly (4) in different zones to ensure that the melt temperature in the runner is evenly distributed to avoid flow instability caused by local cooling; S3, melt injection and mold cavity filling: start the injection machine, inject the molten plastic into the injection molding core (31) through the injection hole (3), at this time, the hot runner component (4) keeps the material in a molten state during the whole process, and no runner cold material is generated. Subsequently, when the melt fills the injection molding core (31) to a certain extent, such as 80%-90%, high-pressure gas is introduced into the injection hole (3), so that the high-pressure gas enters the melt through the injection hole (3), and the high-pressure gas pushes the melt to continue to flow, filling the remaining injection molding core (31). S4, the gas is continuously pressurized to prevent the melt from flowing back and to compensate for the volume shrinkage of the melt when it is cooled. The melt in the injection molding mold (31) is then cooled and solidified, and the gas pressure is kept constant to ensure the dimensional accuracy and surface quality of the product. After the cooling is completed, the high-pressure gas in the injection molding mold (31) is gradually released. The gas can be recycled or safely discharged through a recovery system. Finally, four sets of demolding components (5) are used to complete the demolding of the upper mold (1) and the lower mold (2).

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