A method for controlling nitrogen molding of injection molded parts

Abstract

This invention discloses a method for controlling nitrogen molding of injection molded parts, comprising the following steps: S1: Based on the shape of the injection molded part, dividing the molding cavity corresponding to the injection molded part in the mold into multiple temperature control zones; S2: Presetting multiple sets of cooling parameters; S3: Providing a mold and driving the mold to close via a driving device; S4: Introducing molten material and recording the amount of molten material introduced; S5: Selecting a set of preset cooling parameters to cool the injection molded part; S6: Introducing nitrogen to expel the central molten material and obtaining the amount of material discharged; S7: Molding and unloading to obtain a sample; S8: If all items in the preset cooling parameter set have been tested, proceed to step S9; otherwise, proceed to step S3; S9: Based on the amount of material introduced and discharged, obtaining the hollowness of the workpiece, and based on the hollowness of the workpiece and the appearance of the molded sample, obtaining the optimal test cooling parameters. This invention can facilitate the improvement of the wall thickness uniformity of injection molded parts.

Description

Technical Field

[0001] This invention relates to the technical field of injection molding, and in particular to a method for controlling nitrogen gas molding of injection molded parts. Background Technology

[0002] Injection molding, also known as injection molding, is a molding method that combines injection and molding. The advantages of injection molding include high production speed and efficiency, automated operation, easy product updates and replacements, and the ability to produce complex shapes. Injection molding is suitable for mass production and molding processes involving complex shapes.

[0003] One existing injection molding technique is nitrogen molding. Generally, after molten material is introduced into the mold, the temperature of the injection molded part is gradually reduced from the outside to the inside by lowering the mold temperature. After the outermost layer of the injection molded part cools and solidifies, an inert gas is introduced to blow out the uncooled material in the injection molded part, thereby achieving a hollow structure in the finished product.

[0004] However, since the molding cavity is mostly irregularly shaped while the cooling water pipes inside are mostly uniformly arranged, the distance between the injection molded parts and the cooling water pipes is inconsistent, resulting in inconsistent cooling temperatures in different parts of the injection molded parts. This leads to different material shrinkage rates and warping. At the same time, when inert gas is introduced into the injection molded parts, the inconsistent condensation thickness of the injection molded parts results in low wall thickness uniformity of the finished injection molded parts. Summary of the Invention

[0005] This application provides a method for controlling nitrogen molding of injection molded parts, which can facilitate the improvement of wall thickness uniformity of finished injection molded parts.

[0006] This application provides a method for controlling nitrogen molding of injection molded parts, which adopts the following technical solution:

[0007] A method for controlling nitrogen molding of injection molded parts includes the following steps:

[0008] S1: Based on the shape of the injection molded part, the molding cavity corresponding to the injection molded part in the mold is divided into multiple temperature control zones;

[0009] S2: Preset multiple sets of cooling parameters (cooling parameters include cooling rate, material temperature when nitrogen is introduced, and material forming pressure);

[0010] S3: Provides a mold that is driven to close by a driving device;

[0011] S4: Introduce molten material and record the amount of molten material introduced;

[0012] S5: Select a set of preset cooling parameters to cool the injection molded part;

[0013] S6: Introduce nitrogen gas to expel the molten material in the center and obtain the amount of material discharged;

[0014] S7: Molding and unloading yields a sample part;

[0015] S8: If all items in the preset cooling parameter group have been tested, proceed to step S9; if not, proceed to step S3.

[0016] S9: Based on the material inflow and outflow, obtain the workpiece hollowness, and based on the workpiece hollowness and the sample forming appearance, obtain the optimal test cooling parameters.

[0017] By adopting the above technical solution, the material density of the actual product is calculated by the material inflow and material outflow. The material density corresponding to each cooling parameter is obtained by adjusting the cooling parameters of the same model of product multiple times. Finally, the wall thickness uniformity of the products with each density is screened to obtain the cooling parameters with the best wall thickness uniformity, thus obtaining the actual optimal cooling parameters.

[0018] Preferably, the mold includes an upper mold and a lower mold, a frame is provided on the lower mold, a storage slot is provided on the frame, the upper mold and the lower mold are slidably disposed on the inner sidewall of the storage slot, and a driving device is provided on the frame for driving the upper mold and the lower mold to move relative to each other.

[0019] By adopting the above technical solution, when it is necessary to close the mold, the upper mold and the lower mold are moved relative to each other by the driving device, which makes it easier to close the mold.

[0020] Preferably, the driving device includes a driving block, a driving groove is formed on one side wall of the storage slot, the driving block is slidably disposed on the inner side wall of the driving groove, a first connecting rod is provided between the driving block and the upper mold, one end of the first connecting rod is hinged to the upper mold, and the other end of the first connecting rod is hinged to the driving block; a second connecting rod is provided between the driving block and the lower mold, one end of the second connecting rod is hinged to the lower mold, and the other end of the second connecting rod is hinged to the driving block; a driving assembly for driving the driving block to move is provided on the frame, and a plurality of guiding assemblies for guiding the upper mold and the lower mold are provided on the frame.

[0021] By adopting the above technical solution, when it is necessary to drive the upper mold and the lower mold to move relative to each other, the driving block is first driven to move horizontally by the driving component. The driving block, through the action of the first link and the second link, can facilitate the driving of the upper mold and the lower mold to move vertically relative to each other.

[0022] Preferably, the drive assembly includes a lead screw rotatably disposed within the drive groove, the lead screw being threadedly engaged with the drive block, and a motor mounted on the frame, the output shaft of the motor being fixedly connected to the lead screw.

[0023] By adopting the above technical solution, when it is necessary to drive the drive block to move in the horizontal direction, the motor is started to drive the output shaft to rotate, and the output shaft of the motor drives the lead screw to rotate, thereby facilitating the drive block to move in the horizontal direction.

[0024] Preferably, the guiding assembly includes a guide rod, which is fixedly connected to the frame. The upper mold has a first guide groove, and the lower mold has a second guide groove. The guide rod passes through both the first and second guide grooves. The guide rod is slidably engaged with both the upper and lower molds.

[0025] By adopting the above technical solution, when the upper and lower dies move in the vertical direction, the guide rod can reduce the possibility of the upper and lower dies shifting, thereby facilitating the translational movement of the upper and lower dies.

[0026] Preferably, an insert block is fixedly connected to the upper mold, and a slot for inserting the insert block is provided on the lower mold. The lower mold is also provided with a fixing mechanism for fixing the insert block.

[0027] By adopting the above technical solution, when the upper mold and the lower mold move relative to each other, the insert block is inserted into the slot, and then the insert block is fixed by the fixing mechanism, which can reduce the possibility of separation between the upper mold and the lower mold, and thus reduce the possibility of interruption of the injection molding process.

[0028] Preferably, the fixing mechanism includes a limiting block, the insert block having a limiting groove, the limiting block being able to be inserted into the inner wall of the limiting groove, a sliding groove being formed on one side wall of the slot, the limiting block being slidably disposed on the inner side wall of the sliding groove; a first spring being disposed in the sliding groove, one end of the first spring being fixedly connected to the limiting block, and the other end of the first spring being fixedly connected to the side wall of the sliding groove; a blocking component for blocking the limiting block being disposed in the slot, and a reset component for resetting the limiting block being disposed on the lower mold.

[0029] By adopting the above technical solution, when the plug is inserted into the slot, the first spring is in a compressed state. At this time, the blocking effect of the blocking component on the limiting block is canceled, and the plug continues to be driven to move downward in the vertical direction. When the limiting block is aligned with the limiting groove, the limiting block is inserted into the limiting groove under the elastic force of the first spring, which makes it easier to fix the plug.

[0030] Preferably, the blocking assembly includes a blocking block slidably disposed on the inner sidewall of the slot, and a second spring is disposed within the slot, one end of the second spring being fixedly connected to the blocking block, and the other end of the second spring being fixedly connected to the inner sidewall of the slot.

[0031] By adopting the above technical solution, the blocking block can be conveniently blocked. When the insert block abuts against the blocking block, the insert block drives the blocking block to move downward in the vertical direction. At this time, the second spring is in a compressed state. When the insert block moves upward in the vertical direction, the blocking block can be easily reset under the elastic force of the second spring.

[0032] Preferably, the reset assembly includes a hydraulic cylinder, a mounting groove is formed on one side wall of the sliding groove, the hydraulic cylinder is installed in the mounting groove, and the piston rod of the hydraulic cylinder is hinged to a third connecting rod, the end of the third connecting rod away from the hydraulic cylinder being hinged to the limiting block.

[0033] By adopting the above technical solution, when it is necessary to drive the limit block to reset, the piston rod is driven by the hydraulic cylinder to move. The piston rod of the hydraulic cylinder drives the limit block to move away from the insertion block through the third connecting rod, which makes it easier to drive the limit block to reset.

[0034] In summary, this application has the following beneficial effects:

[0035] 1. The material density of the actual product is calculated by the material input and output. The material density corresponding to each cooling parameter is obtained by adjusting the cooling parameters of the same model of product multiple times. Finally, the wall thickness uniformity of the products with each density is screened to find the cooling parameters with the best wall thickness uniformity, thus obtaining the actual best cooling parameters.

[0036] 2. When the insert block is inserted into the slot, the first spring is in a compressed state. At this time, the blocking component stops the blocking effect on the limiting block, and the insert block continues to move downward in the vertical direction. When the limiting block is aligned with the limiting groove, the limiting block is inserted into the limiting groove under the elastic force of the first spring, which makes it easier to fix the insert block.

[0037] 3. By setting the blocking block, it is easy to block the limiting block. When the insert block abuts against the blocking block, the insert block drives the blocking block to move downward in the vertical direction. At this time, the second spring is in a compressed state. When the insert block moves upward in the vertical direction, the blocking block can easily reset under the elastic force of the second spring. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0039] Figure 2 yes Figure 1 A magnified view of a section at point A in the middle;

[0040] Figure 3 This is a schematic diagram of the display driving device in this invention;

[0041] Figure 4 This is a cross-sectional view showing the fixing mechanism in this invention.

[0042] Explanation of reference numerals in the attached drawings: 1. Mold; 11. Upper mold; 111. Air inlet; 12. Lower mold; 13. Insert block; 14. Slot; 15. Injection groove; 2. Frame; 21. Storage slot; 3. Drive device; 311. Drive block; 312. Drive groove; 313. First connecting rod; 314. Second connecting rod; 32. Drive assembly; 321. Lead screw; 322. Motor; 33. Guide assembly; 331. Guide rod; 332. First guide groove; 333. Second guide groove; 4. Fixing mechanism; 411. Limiting block; 412. Limiting groove; 413. Sliding groove; 414. First spring; 42. Blocking assembly; 421. Blocking block; 422. Second spring; 43. Reset assembly; 431. Hydraulic cylinder; 432. Third connecting rod; 433. Mounting groove. Detailed Implementation

[0043] This invention discloses a method for controlling nitrogen molding of injection molded parts, comprising the following steps:

[0044] S1: Based on the shape of the injection molded part, the molding cavity corresponding to the injection molded part in the mold is divided into multiple temperature control zones;

[0045] S2: Preset multiple sets of cooling parameters (cooling parameters include cooling rate, material temperature when nitrogen is introduced, and material forming pressure);

[0046] S3: A mold 1 is provided, which is driven to close by a driving device 3;

[0047] S4: Introduce molten material and record the amount of molten material introduced;

[0048] S5: Select a set of preset cooling parameters to cool the injection molded part;

[0049] S6: Introduce nitrogen gas to expel the molten material in the center and obtain the amount of material discharged;

[0050] S7: Molding and unloading yields a sample part;

[0051] S8: If all items in the preset cooling parameter group have been tested, proceed to step S9; if not, proceed to step S3.

[0052] S9: Based on the material inflow and outflow, obtain the workpiece hollowness, and based on the workpiece hollowness and the sample forming appearance, obtain the optimal test cooling parameters.

[0053] Example 1

[0054] like Figure 1 As shown, multiple temperature sensors are installed on both the upper mold 11 and the lower mold 12; multiple pressure sensors are also installed on both the upper mold 11 and the lower mold 12. An air inlet 111 for introducing nitrogen gas is opened on one side of the upper mold 11. The material density of the actual product is calculated by the material input and output rates. The material density corresponding to each cooling parameter is obtained by repeatedly adjusting the cooling parameters of the same model of product. Finally, the wall thickness uniformity of products with various densities is screened to determine the optimal cooling parameters for wall thickness uniformity, thus obtaining the actual optimal cooling parameters.

[0055] Example 2

[0056] The difference between this embodiment and Embodiment 1 is that this embodiment provides a mold 1, such as... Figure 1 As shown, mold 1 includes an upper mold 11 and a lower mold 12, both of which are square. Injection grooves 15 are formed on the inner sides of both the upper mold 11 and the lower mold 12. The injection grooves 15 have a circular cross-section and extend vertically. A frame 2 is mounted on the lower mold 12. The frame 2 is square and has a storage slot 21 with a square cross-section extending along the length of the frame 2. The upper mold 11 and the lower mold 12 are slidably mounted on the inner wall of the storage slot 21. A drive device 3 is provided on the frame 2 to drive the upper mold 11 and the lower mold 12 to move relative to each other. When it is necessary to close mold 1, the drive device 3 drives the upper mold 11 and the lower mold 12 to move relative to each other, thereby facilitating the closure of mold 1.

[0057] like Figure 1 , Figure 2 and Figure 3As shown, the driving device 3 includes a driving block 311, which is square in shape. A driving groove 312 is formed on one side wall of the storage slot 21. The driving groove 312 has a square cross-section and extends along the length of the frame 2. The driving block 311 is slidably disposed on the inner side wall of the driving groove 312 along the length of the frame 2. A first connecting rod 313 is provided between the driving block 311 and the upper mold 11. The first connecting rod 313 has a square cross-section, and one end of the first connecting rod 313 is hinged to one side of the upper mold 11. The other end is hinged to the top of the drive block 311; a second connecting rod 314 is provided between the drive block 311 and the lower mold 12. The cross-section of the second connecting rod 314 is square. One end of the second connecting rod 314 is hinged to one side of the lower mold 12, and the other end of the second connecting rod 314 is hinged to the bottom of the drive block 311; a drive assembly 32 for driving the drive block 311 to move along the length direction of the frame 2 is provided on the frame 2, and a plurality of guide assemblies 33 for guiding the upper mold 11 and the lower mold 12 are provided on the frame 2.

[0058] When it is necessary to drive the upper mold 11 and the lower mold 12 to move relative to each other, the driving block 311 is first driven to move horizontally through the driving component 32. The driving block 311, through the action of the first connecting rod 313 and the second connecting rod 314, can facilitate the driving of the upper mold 11 and the lower mold 12 to move vertically relative to each other.

[0059] like Figure 1 , Figure 2 and Figure 3 As shown, the drive assembly 32 includes a lead screw 321, which is arranged along the length of the frame 2. Both ends of the lead screw 321 are rotatably mounted on the inner wall of the drive groove 312 via bearings. The lead screw 321 passes through the drive block 311 and is threadedly engaged with the drive block 311. A motor 322 is bolted to the frame 2, and the output shaft of the motor 322 is fixedly connected to the lead screw 321. When it is necessary to drive the drive block 311 to move horizontally, the motor 322 is started to drive the output shaft to rotate, and the output shaft of the motor 322 drives the lead screw 321 to rotate, thereby facilitating the horizontal movement of the drive block 311.

[0060] like Figure 1 and Figure 2As shown, the guide assembly 33 includes a guide rod 331. The guide rod 331 has a circular cross-section and is arranged vertically. Both ends of the guide rod 331 are fixedly connected to the inner wall of the placement groove 21. The upper mold 11 has a first guide groove 332, which has a circular cross-section and extends vertically. The lower mold 12 has a second guide groove 333, which also has a circular cross-section and extends vertically. The guide rod 331 passes through both the first guide groove 332 and the second guide groove 333. The guide rod 331 slides vertically with the upper mold 11 and with the lower mold 12. When the upper mold 11 and the lower mold 12 move vertically, the guide rod 331 helps reduce the possibility of misalignment between them, thus facilitating translational movement.

[0061] like Figure 1 , Figure 2 and Figure 4 As shown, a square-shaped insert block 13 is fixedly connected to the bottom of the upper mold 11. A slot 14 for inserting the insert block 13 is provided on the lower mold 12. The slot 14 has a square cross-section and extends vertically. A fixing mechanism 4 for fixing the insert block 13 is provided on the lower mold 12. When the upper mold 11 and lower mold 12 move relative to each other, the insert block 13 is inserted into the slot 14 and then fixed by the fixing mechanism 4. This reduces the possibility of separation between the upper mold 11 and lower mold 12, thereby reducing the possibility of interruption in the injection molding process.

[0062] like Figure 1 , Figure 2 and Figure 4 As shown, the fixing mechanism 4 includes a limiting block 411, which is square in shape. The insertion block 13 has a limiting groove 412 on one side near the limiting groove 412. The limiting groove 412 has a square cross-section and extends along the length of the limiting block 411. The limiting block 411 can be inserted into the inner wall of the limiting groove 412. A sliding groove 413 is provided on one side wall of the slot 14. The sliding groove 413 has a square cross-section and extends along the length of the limiting block 411. The limiting block 411 is slidably disposed on the inner wall of the sliding groove 413 along the length of the limiting block 411.

[0063] like Figure 4As shown, a first spring 414 is provided in the sliding groove 413. The first spring 414 is arranged along the length direction of the limiting block 411. One end of the first spring 414 is fixedly connected to the limiting block 411, and the other end of the first spring 414 is fixedly connected to the side wall of the sliding groove 413. A blocking component 42 for blocking the limiting block 411 is provided in the slot 14, and a reset component 43 for resetting the limiting block 411 is provided on the lower mold 12. When the insert 13 is inserted into the slot 14, the first spring 414 is in a compressed state. At this time, the blocking effect of the blocking component 42 on the limiting block 411 is canceled, and the insert 13 continues to move downward in the vertical direction. When the limiting block 411 is aligned with the limiting groove 412, the limiting block 411 is inserted into the limiting groove 412 under the elastic force of the first spring 414, thereby facilitating the fixing of the insert 13.

[0064] like Figure 4 As shown, the blocking assembly 42 includes a blocking block 421, which is square in shape. The blocking block 421 is slidably disposed on the inner wall of the slot 14 in a vertical direction. A second spring 422 is disposed inside the slot 14, which is also vertically disposed. One end of the second spring 422 is fixedly connected to the bottom of the blocking block 421, and the other end is fixedly connected to the inner wall of the slot 14. The blocking block 421 facilitates the blocking of the limiting block 411. When the insert block 13 abuts against the blocking block 421, the insert block 13 drives the blocking block 421 to move downward in a vertical direction. At this time, the second spring 422 is in a compressed state. When the insert block 13 moves upward in a vertical direction, the blocking block 421 can easily reset under the elastic force of the second spring 422.

[0065] like Figure 4 As shown, the reset assembly 43 includes a hydraulic cylinder 431, which is arranged along the length of the limiting block 411. A mounting groove 433 is provided on one side wall of the sliding groove 413, which extends along the width of the limiting block 411. The hydraulic cylinder 431 is installed in the mounting groove 433 by bolts. The piston rod of the hydraulic cylinder 431 is hinged to a third connecting rod 432. The cross-section of the third connecting rod 432 is square, and the end of the third connecting rod 432 away from the hydraulic cylinder 431 is hinged to the limiting block 411.

[0066] When it is necessary to drive the limit block 411 to reset, the piston rod is driven to move by the hydraulic cylinder 431. The piston rod of the hydraulic cylinder 431 drives the limit block 411 to move away from the insertion block 13 through the third connecting rod 432, thereby facilitating the drive of the limit block 411 to reset.

[0067] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for controlling nitrogen gas injection molding of injection molded parts, characterized in that, The construction steps include: S1: Based on the shape of the injection molded part, the molding cavity corresponding to the injection molded part in the mold is divided into multiple temperature control zones; S2: Preset multiple sets of cooling parameters, including cooling rate, material temperature when nitrogen is introduced, and material forming pressure; S3: Provide a mold (1) and drive the mold to close by a drive device (3); S4: Introduce molten material and record the amount of molten material introduced; S5: Select a set of preset cooling parameters to cool the injection molded part; S6: Introduce nitrogen gas to expel the molten material in the center and obtain the amount of material discharged; S7: Molding and unloading yields a sample part; S8: If all items in the preset cooling parameter group have been tested, proceed to step S9; if not, proceed to step S3. S9: Based on the material inflow and outflow, obtain the workpiece hollowness, and based on the workpiece hollowness and the sample forming appearance, obtain the optimal test cooling parameters. The mold (1) includes an upper mold (11) and a lower mold (12). A frame (2) is provided on the lower mold (12). A storage slot (21) is provided on the frame (2). The upper mold (11) and the lower mold (12) are both slidably disposed on the inner side wall of the storage slot (21). A driving device (3) for driving the upper mold (11) and the lower mold (12) to move relative to each other is provided on the frame (2). The driving device (3) includes a driving block (311). A driving groove (312) is provided on one side wall of the storage slot (21). The driving block (311) is slidably disposed on the inner side wall of the driving groove (312). A first connecting rod (313) is provided between the driving block (311) and the upper mold (11). One end of the first connecting rod (313) is hinged to the upper mold (11). The other end of the rod (313) is hinged to the drive block (311); a second connecting rod (314) is provided between the drive block (311) and the lower mold (12), one end of the second connecting rod (314) is hinged to the lower mold (12), and the other end of the second connecting rod (314) is hinged to the drive block (311); a drive assembly (32) for driving the drive block (311) to move is provided on the frame (2), and a guide assembly (33) for guiding the upper mold (11) and the lower mold (12) is provided on the frame (2); an insert block (13) is fixedly connected to the upper mold (11), and a slot (14) for inserting the insert block (13) is provided on the lower mold (12), and a fixing mechanism (4) for fixing the insert block (13) is provided on the lower mold (12).

2. The method for controlling nitrogen gas molding of injection molded parts according to claim 1, characterized in that: The drive assembly (32) includes a lead screw (321), which is rotatably disposed in the drive groove (312). The lead screw (321) is threadedly engaged with the drive block (311). A motor (322) is mounted on the frame (2), and the output shaft of the motor (322) is fixedly connected to the lead screw (321).

3. The method for controlling nitrogen gas molding of injection molded parts according to claim 1, characterized in that: The guide assembly (33) includes a guide rod (331), which is fixedly connected to the frame (2). The upper mold (11) has a first guide groove (332), and the lower mold (12) has a second guide groove (333). The guide rod (331) passes through the first guide groove (332) and the second guide groove (333). The guide rod (331) is slidably engaged with the upper mold (11) and the lower mold (12).

4. The method for controlling nitrogen gas molding of injection molded parts according to claim 1, characterized in that: The fixing mechanism (4) includes a limiting block (411), a limiting groove (412) is provided on the insert block (13), the limiting block (411) can be inserted into the inner side wall of the limiting groove (412), a sliding groove (413) is provided on one side wall of the slot (14), and the limiting block (411) is slidably disposed on the inner side wall of the sliding groove (413); a first spring (414) is provided in the sliding groove (413), one end of the first spring (414) is fixedly connected to the limiting block (411), and the other end of the first spring (414) is fixedly connected to the side wall of the sliding groove (413); a blocking component (42) for blocking the limiting block (411) is provided in the slot (14), and a reset component (43) for resetting the limiting block (411) is provided on the lower mold (12).

5. The method for controlling nitrogen gas molding of injection molded parts according to claim 4, characterized in that: The blocking assembly (42) includes a blocking block (421), which is slidably disposed on the inner sidewall of the slot (14). A second spring (422) is disposed in the slot (14), one end of which is fixedly connected to the blocking block (421), and the other end of which is fixedly connected to the inner sidewall of the slot (14).

6. The method for controlling nitrogen gas injection molding of injection molded parts according to claim 4, characterized in that: The reset assembly (43) includes a hydraulic cylinder (431). A mounting groove (433) is provided on one side wall of the sliding groove (413). The hydraulic cylinder (431) is installed in the mounting groove (433). The piston rod of the hydraulic cylinder (431) is hinged to a third connecting rod (432). The end of the third connecting rod (432) away from the hydraulic cylinder (431) is hinged to the limiting block (411).

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