Injection blow hollow forming device capable of actively regulating wall thickness

Abstract

The present application relates to injection blow molding device technical field, specifically to a kind of implementation wall thickness active regulation's injection blow hollow forming device, it includes first injection outer mold, blow molding outer mold and inner mold;Inner mold includes baffle, mold core and deformation ring.The present application is by setting the deformation ring that can occur deformation, under the premise of guaranteeing that outer surface is smooth without protrusion in the process of injection molding, increase the inner layer embryo wall thickness of high-stretching position in later blow molding process, facilitate demoulding, while, reduce the risk of blow molding rupture, and injection molding process and blow molding process share same inner mold, reduce process, improve molding efficiency, guarantee molding effect.And can realize double-layer injection molding, break through the performance limit of single material, reduce raw material cost.Through adjusting assembly, according to the softness and hardness of inner layer embryo, self-adapting adjustment space that deformation ring can occur deformation;Regardless of the fluctuation of the hardening degree of inner layer embryo, ensure that uniform, stable wall thickness can be formed in high-stretching risk area.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of injection blow molding device, and particularly relates to an injection blow hollow molding device for realizing active regulation of wall thickness. BACKGROUND

[0002] Injection blow molding is a common process for producing hollow plastic containers, and its basic process is: first, a parison is prepared by injection molding, and then the parison is placed in a blow mold, high-pressure gas is introduced into the parison to make it expand and adhere to the mold cavity, and then the parison is cooled and shaped into a final product. This process is mature and efficient, and is suitable for mass production. In the market demand for product differentiation and functionalization, multi-layer injection blow molding technology has been developed. This technology forms a multi-layer structure composed of different materials on the same parison through sequential injection molding. In the process of continuously optimizing the basic process, how to efficiently and accurately realize the transfer and positioning of the parison between the injection and blow stations and other operational problems have been effectively solved by mature solutions such as automatic manipulators and rotary worktables. For example, a plastic bottle blow molding integrated equipment is disclosed in Chinese patent application No. CN120620616A.

[0003] However, whether it is a single-layer or multi-layer container, the material's radial stretching ratio at positions with sharp curvature changes such as the bottle mouth and bottle shoulder is much larger than that at flat positions such as the bottle body. This often leads to excessively thin wall thickness at these positions after blow molding, and even rupture due to excessive stretching, which seriously affects product yield. To solve this problem, the existing technology usually increases the wall thickness of the parison at these expected high-stretching positions directly during the injection molding stage. However, simply thickening the local area will form a protrusion or thickening step on the inner wall of the parison at this position, which will generate a large frictional resistance with the mold during demolding from the mold core, causing demolding difficulties, and even causing deformation or damage to the parison, thereby affecting product quality and production stability. In addition, during multi-layer injection molding, the inner layer parison, which has been preliminarily cooled, will affect the flow and distribution of the outer layer material as an "inner mold", and fluctuations in the hardening degree of the inner layer parison may lead to uneven wall thickness of the outer layer. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides an injection blow hollow molding device for realizing active regulation of wall thickness, which solves the problem of rupture due to excessive stretching at positions with large stretching amounts in the prior art, and the problem of uneven wall thickness of the outer layer caused by fluctuations in the hardening degree of the inner layer parison during multi-layer injection molding.

[0005] The injection blow hollow molding device for realizing active regulation of wall thickness according to the present application adopts the following technical scheme, comprising a first injection molding outer mold, a blow molding outer mold, and an inner mold; the inner mold can be combined with the first injection molding outer mold, and can be combined with the blow molding outer mold;

[0006] The first injection mold has a first injection port; the inner mold comprises:

[0007] The baffle is horizontally arranged, and a gas injection hole is arranged in the center of the baffle;

[0008] The mold core has a first groove on the outer peripheral wall, the first groove is coaxial with the mold core, and the first groove is annular; the mold core is hollow inside and is in communication with the gas injection hole, and a plurality of through holes are arranged on the peripheral wall and are in communication inside and outside;

[0009] The deformation ring is made of heat-resistant elastic material; the deformation ring is installed in the first groove; the upper and lower ends of the deformation ring are fixedly connected to the mold core; the outer surface of the deformation ring is smoothly connected to the outer peripheral wall of the mold core, and together forms a forming surface of the inner mold;

[0010] When the inner mold and the first injection mold are combined, a first injection cavity for forming an inner layer preform is formed between the two; when the molten material is injected into the first injection cavity, the material pressure acts on the deformation ring, driving the deformation ring to produce an inward elastic concave deformation, thereby increasing the wall thickness of the corresponding position of the inner layer preform;

[0011] When the inner mold and the blow mold are combined, a blow cavity is defined therebetween.

[0012] Optionally, the injection-blowing hollow forming device for actively controlling the wall thickness further comprises a second injection mold. The inner cavity of the second injection mold has a larger radial dimension than the inner cavity of the first injection mold, and the inner cavity of the second injection mold has a larger axial dimension than the inner cavity of the first injection mold. When the inner mold carrying the inner layer preform is combined with the second injection mold, a second injection cavity for forming an outer layer preform is formed between the outer surface of the inner layer preform and the inner surface of the second injection mold. The second injection mold has a second injection port. The inner layer preform and the outer layer preform form a preform body.

[0013] Optionally, the inner mold further comprises an adjusting assembly for adjusting the axial length of the first groove for deformation of the deformation ring according to the hardening degree of the inner layer preform when the material is injected into the second injection cavity, so that the axial length of the first groove for deformation of the deformation ring is positively correlated with the hardness of the inner layer preform.

[0014] Optionally, the adjusting assembly comprises a shielding piece and a compression spring; the shielding piece is movably arranged in the inner part of the mold core, and in the initial state, the shielding piece has a pre-set length of overlapping part with the first groove to shield the first groove; the compression spring vertically extends, and the two ends are respectively connected to the baffle and the moving shaft.

[0015] Optionally, the second injection port is arranged at the lower end of the second injection outer mold; the shielding member is a movable shaft; the outer diameter of the movable shaft is equal to the inner diameter of the mold core and the inner diameter of the deformation ring; the movable shaft is slidably arranged in the mold core; the movable shaft is provided with an air channel, the air channel is communicated with the air injection hole and the through hole; the outer peripheral wall of the movable shaft is provided with a second groove; the second groove is annular; in the initial state, the upper part of the second groove and the lower part of the first groove have a preset length of overlapping part.

[0016] Optionally, the mold core comprises a first shell and a second shell. The upper end of the first shell is fixedly connected to the baffle. The second shell is coaxially arranged below the first shell. The upper and lower ends of the deformation ring are fixedly connected to the lower end of the first shell and the upper end of the second shell, respectively.

[0017] Optionally, the diameter of the second injection cavity gradually decreases from top to bottom.

[0018] Optionally, the setting position of the first groove and the deformation ring along the axial direction of the mold core corresponds to the area where the expected stretching amount in the subsequent blow molding process of the molded product is greater than other parts.

[0019] Optionally, the deformation ring is made of silicone rubber.

[0020] Optionally, the blow-molded hollow forming device for realizing active wall thickness control further comprises a first injection molding machine, a second injection molding machine and a blow molding machine. The first injection outer mold is installed on the first injection molding machine. The second injection outer mold is installed on the second injection molding machine. The blow molding outer mold is installed on the blow molding machine.

[0021] The beneficial effects of the present application are: by arranging the deformation ring capable of deforming, the inner layer embryo wall thickness of the high stretching amount position in the later blow molding process is increased during the injection molding process, and the outer surface of the inner layer embryo is smooth without protrusion, which reduces the risk of blow molding rupture, facilitates the inner layer embryo to be taken out from the first injection outer mold, and the injection molding process and the blow molding process share the same inner mold. The inner layer embryo does not need to be taken off from the inner mold after injection molding, but can be directly transferred and completed blow molding, reducing the demolding process and avoiding affecting the quality of the inner layer embryo. The molding efficiency is improved, the molding effect is guaranteed, and high-efficiency and stable continuous production is realized.

[0022] Further, by arranging the first injection outer mold and the second injection outer mold, double-layer injection molding can be realized under the premise of avoiding blow molding rupture, so that the inner layer material and the outer layer material can be matched according to actual needs, and the performance limitation of single material is broken. Expensive high-performance materials such as barrier materials can be used only for the necessary inner layer, and materials with lower cost and good mechanical properties can be used as the outer layer, which ensures the core functions of the product such as preservation and chemical resistance, while reducing the cost of raw materials.

[0023] Further, by setting the adjusting assembly, the space available for the deformation ring to deform can be adaptively adjusted according to the softness of the inner layer embryo. When the inner layer embryo is relatively soft, the initial deformation space is maintained to avoid excessive compensation. When the inner layer embryo is harder and the flow resistance of the outer layer material is greater, the deformation space is increased by the displacement of the moving shaft to enable the deformation ring to produce a greater deformation to inject more outer layer material. The present application can ensure that during the outer layer injection molding process, regardless of the fluctuation of the hardening degree of the inner layer embryo, a uniform and stable wall thickness can be formed in the high-stretch risk area such as the bottle shoulder, solving the problem of uneven outer layer wall thickness caused by uncertain inner layer state in multi-layer injection molding. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0025] Figure 1 FIG. 1 is a schematic diagram of the overall structure of the injection-blowing hollow forming device for actively regulating wall thickness according to the present application;

[0026] Figure 2 FIG. 2 is a schematic diagram of the structure when the first injection molding outer mold and the inner mold are closed according to the present application;

[0027] Figure 3 FIG. 3 is a schematic diagram of the structure when the second injection molding outer mold and the inner mold are closed according to the present application; Figure 2

[0028] Figure 4 FIG. 4 is a cross-sectional view of A-A in FIG. 3 according to the present application; Figure 3

[0029] Figure 5 FIG. 5 is a schematic diagram of the structure when the blow molding outer mold and the inner mold are closed according to the present application;

[0030] Figure 6 FIG. 6 is a schematic diagram of the state of the second injection molding outer mold and the inner mold during the injection molding of the outer layer embryo when the hardening degree of the inner layer embryo is low according to the present application;

[0031] Figure 7 FIG. 7 is a schematic diagram of the state of the second injection molding outer mold and the inner mold during the injection molding of the outer layer embryo when the hardening degree of the inner layer embryo is high according to the present application;

[0032] Figure 8 FIG. 8 is a schematic diagram of the structure when the blow molding outer mold and the inner mold are closed according to the present application.

[0033] In the drawings:

[0034] 100, first injection molding outer mold; 101, first injection port;​​

[0035] 200, blow mold; 210, blow cavity;

[0036] 300, inner mold; 310, baffle; 311, gas injection hole; 320, mold core; 321, first shell; 322, second shell; 323, through hole; 330, deformation ring; 340, first injection cavity; 350, adjustment assembly; 351, moving shaft; 352, second groove; 353, compression spring;

[0037] 400, second injection mold; 401, second injection port; 410, second injection cavity;

[0038] 500, first injection molding machine;

[0039] 600, second injection molding machine. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0041] As shown in Figures 1 to 8 The injection-blowing hollow forming device for realizing active control of wall thickness provided by the present application comprises a first injection mold 100, a blow mold 200 and an inner mold 300. The inner mold 300 can be combined with the first injection mold 100, and can be combined with the blow mold 200.

[0042] The first injection mold 100 has a first injection port 101. The inner mold 300 comprises a baffle 310, a mold core 320 and a deformation ring 330.

[0043] The baffle 310 is horizontally arranged, and the baffle 310 is provided with a gas injection hole 311 passing through the upper and lower portions.

[0044] The mold core 320 comprises a first shell 321 and a second shell 322. The upper end of the first shell 321 is fixedly connected to the baffle 310. The second shell 322 is coaxially arranged below the first shell 321. A first groove is defined between the lower end of the first shell 321 and the upper end of the second shell 322, the first groove is coaxial with the mold core 320, and the first groove is annular. The interiors of the first shell 321 and the second shell 322 are hollow and communicate with the gas injection hole 311, and a plurality of through holes 323 are formed in the peripheral wall of the second shell 322 and pass through the interior and exterior of the second shell 322. The positions of the first groove and the deformation ring 330 along the axial direction of the mold core 320 correspond to the regions of the molded product where the expected stretching amount in the subsequent blow molding process is greater than other regions.

[0045] The deformation ring 330 is made of heat-resistant elastic material, such as silicone rubber. The deformation ring 330 is installed in the first groove, and the upper and lower ends of the deformation ring 330 are fixedly connected to the lower end of the first shell 321 and the upper end of the second shell 322, respectively. The outer surface of the deformation ring 330 smoothly connects with the outer peripheral wall of the mold core 320, and together forms the molding surface of the inner mold 300.

[0046] When the inner mold 300 is combined with the first injection mold 100, a first injection cavity 340 for molding an inner layer preform is formed between the two. The molten material exerts pressure on the deformation ring 330, driving the deformation ring 330 to produce an inward elastic concave deformation, thereby increasing the wall thickness of the inner layer preform at the corresponding position. When the inner mold 300 is combined with the blow mold 200, a blow cavity 210 is defined between the two.

[0047] In use, the inner mold 300 is combined with the first injection mold 100, and molten material is injected into the first injection cavity 340 through the first injection port 101. During the injection process, the material exerts an inward force on the deformation ring 330, causing the deformation ring 330 to deform inwardly and concavely, thereby increasing the thickness of the first injection cavity 340 at the corresponding position, allowing more material to flow into and accumulate there, and thereby increasing the thickness of the inner layer preform at the corresponding position. After the injection is completed, the inner layer preform is cooled for a period of time, and then the inner mold 300 and the injection-formed inner layer preform are simultaneously removed from the first injection mold 100 and transferred to a blow molding station.

[0048] The inner layer preform is inserted into the blow mold 200, and the inner mold 300 is combined with the blow mold 200. After the combination is completed, high-pressure gas is injected into the gas injection hole 311, the gas enters the cavity inside the mold core 320 through the gas injection hole 311, and then passes through the through hole 323 on the peripheral wall of the mold core 320 to the space between the mold core 320 and the inner layer preform, and acts on the inner surface of the inner layer preform, causing it to expand under high pressure and adhere to the inner wall of the blow mold 200, completing the blow molding process. During blow molding, the position of the inner layer preform with a thicker thickness corresponds to an area with a larger expected stretching amount than other parts, such as the shoulder position.

[0049] The present application provides a deformation ring 330 that can deform during injection molding, increasing the wall thickness of the inner layer preform at high-stretching locations during the later blow molding process. The outer surface of the inner layer preform is smooth and free of protrusions, reducing the risk of blow molding rupture and facilitating the removal of the inner layer preform from the first injection mold 100. The injection process and the blow molding process share the same inner mold 300. The inner layer preform does not need to be removed from the inner mold 300 after injection molding, but can be directly transferred and completed blow molding, reducing the demolding process and avoiding affecting the quality of the inner layer preform. The molding efficiency is improved while ensuring the molding effect, which is conducive to realizing efficient and stable continuous production.

[0050] In a further embodiment, the injection blow molding device with active wall thickness control further comprises a second injection outer mold 400. The inner cavity of the second injection outer mold 400 has a larger radial dimension than the inner cavity of the first injection outer mold 100, and the inner cavity of the second injection outer mold 400 has a larger axial dimension than the inner cavity of the first injection outer mold 100. When the inner mold 300 with the inner layer parison is combined with the second injection outer mold 400, a second injection cavity 410 for forming an outer layer parison is formed between the outer surface of the inner layer parison and the inner surface of the second injection outer mold 400. The second injection outer mold 400 has a second injection gate 401. The inner layer parison and the outer layer parison constitute a parison body.

[0051] In the injection blow process, the inner mold 300 is first combined with the first injection outer mold 100, and an equal amount of molten inner layer material is injected into the first injection cavity 340 through the first injection gate 101. In the above process, the force of the material on the deformation ring 330 causes the deformation ring 330 to deform slightly, and the inner layer material is slightly aggregated at the position of the deformation ring 330. After the injection is completed, the inner layer parison is cooled, and then the inner mold 300 and the injection-formed inner layer parison are removed from the first injection outer mold 100 and transferred to the second injection station.

[0052] The inner layer parison is inserted into the second injection cavity 410. After the inner mold 300 is combined with the second injection outer mold 400, the outer layer material is injected into the second injection cavity 410 through the second injection gate 401. During the injection process, the material exerts an inward force on the deformation ring 330 through the inner layer parison, causing the deformation ring 330 and the inner layer parison to deform inwardly, thereby increasing the thickness of the second injection cavity 410 at the corresponding position, allowing more outer layer material to flow into and aggregate at this position, further increasing the thickness of the outer layer parison at the corresponding position. After the injection is completed, a period of cooling is performed, and the inner mold 300 and the parison body are removed from the second injection outer mold 400 and transferred to the blow molding station for blow molding.

[0053] The present application sets the first injection outer mold 100 and the second injection outer mold 400, which can realize double-layer injection molding under the premise of avoiding blow molding rupture, so that the inner layer material and the outer layer material can be matched according to actual needs, breaking through the performance limitations of single material. Expensive high-performance materials such as barrier materials can be used only for the necessary inner layer, while materials with lower cost and good mechanical properties are used as the outer layer, which can ensure the core functions of the product such as freshness preservation and chemical resistance while reducing the cost of raw materials.

[0054] In a further embodiment, the inner mold 300 further comprises an adjusting assembly 350, which comprises a blocking member and a compression spring 353, the blocking member being movably arranged inside the mold core 320. The adjusting assembly 350 is used to adjust the axial length of the first groove blocked by the blocking member according to the hardening degree of the inner layer preform when injecting the material into the second injection cavity 410, so that the axial length of the first groove for the deformation of the deformation ring 330 is positively correlated with the hardness of the inner layer preform.

[0055] The second material injection port 401 is arranged at the lower end of the second injection outer mold 400. The blocking member is a moving shaft 351. The outer diameter of the moving shaft 351 is equal to the inner diameter of the mold core 320 and the inner diameter of the deformation ring 330. The moving shaft 351 is slidably arranged inside the mold core 320. The moving shaft 351 is provided with an air passage, which is in communication with the air injection hole 311 and the through hole 323. The outer peripheral wall of the moving shaft 351 is provided with a second groove 352. The second groove 352 is annular. In the initial state, the upper part of the second groove 352 has a predetermined length of overlapping part with the lower part of the first groove. The compression spring 353 extends vertically, and the two ends are connected to the baffle 310 and the moving shaft 351, respectively.

[0056] In the process of injection molding, the inner mold 300 is first combined with the first injection outer mold 100, and an equal amount of molten inner layer material is injected into the first injection cavity 340 through the first material injection port 101. In the above process, the force of the material on the deformation ring 330 causes the deformation ring 330 to deform slightly, and the inner layer material is slightly aggregated at the position of the deformation ring 330. After the material injection is completed, the inner layer preform is cooled, and then the inner mold 300 and the injection molded inner layer preform are taken out from the first injection outer mold 100 and transferred to the second injection station.

[0057] The inner layer preform is inserted into the second injection cavity 410. After the inner mold 300 is combined with the second injection outer mold 400, the outer layer material is injected into the second injection cavity 410 through the second material injection port 401. During the injection process, the material exerts an inward force on the deformation ring 330 through the inner layer preform, which promotes the inward deformation of the deformation ring 330 and the inner layer preform, thereby increasing the thickness of the second injection cavity 410 at the corresponding position, allowing more outer layer material to flow into and aggregate at this position, further increasing the thickness of the outer layer preform at the corresponding position.

[0058] When the outer layer embryo injection molding is carried out, the hardening degree of the inner layer embryo can be judged according to the injection pressure value displayed on the corresponding injection molding machine, and the internal relationship is: the harder the inner layer embryo, the greater the resistance to the flow of the outer layer melt, and the higher the corresponding injection molding machine output peak pressure and holding pressure required to maintain the set injection speed. Conversely, when the inner layer embryo is soft, the actual resistance encountered by the outer layer material when flowing in the second injection cavity 410 is relatively small. Therefore, in order to maintain the set injection speed, the injection peak pressure and the subsequent holding pressure required by the corresponding injection molding machine are relatively small.

[0059] When the inner layer embryo is soft, the injection pressure generated by the second injection molding machine 600 when injecting the outer layer material into the second injection cavity 410 will cause the inner layer embryo to produce a small elastic deformation, thereby dissipating part of the energy and transmitting a smaller effective axial thrust to the moving shaft 351. The moving shaft 351 only moves slightly upward or basically remains in place under the action of the compression spring 353, so that the axial length of the first groove blocked by the moving shaft 351 almost remains unchanged or slightly increases, providing a smaller space for the deformation of the deformation ring 330. However, in this case, the force of the outer layer material on the inner layer embryo is concentrated on the position directly opposite the overlap of the first groove and the second groove 352, and the deformation amount of the deformation ring 330 matches the smaller flow resistance brought by the softer inner layer, forming a uniform outer layer wall thickness.

[0060] When the inner layer embryo is soft, in the process of injecting the outer layer material, the material exerts a radial inward pressure on the inner layer embryo, which is transmitted to the inner wall of the inner layer embryo through the inner layer embryo itself. Since the inner layer embryo is rigidly supported by the first housing 321 and the second housing 322 on most of its inner wall except the area corresponding to the deformation ring 330, it cannot move, and the interval available for the deformation of the deformation ring 330 is relatively short. Therefore, the pressure is concentrated on the bottom inner wall of the inner layer embryo, and the second injection port 401 is arranged at the lower end of the second injection outer mold 400, so the injection pressure directly acts on the lower end surface of the moving shaft 351. When it overcomes the elastic force of the compression spring 353 and the gravity of the moving shaft 351, it pushes the moving shaft 351 to move upward. During the upward movement of the moving shaft 351, the length of the first groove blocked by the moving shaft 351 decreases, the length of the overlap of the first groove and the second groove 352 increases, and the space available for the deformation of the deformation ring 330 increases. When the length of the overlap of the first groove and the second groove 352 is greater than a predetermined value, the force exerted by the outer layer material on the inner layer embryo is sufficient to cause the inner layer embryo and the deformation ring 330 to deform.

[0061] And when the inner layer embryo is harder, the moving shaft 351 moves a longer distance, and the first groove and the second groove 352 coincide for a longer length, thereby ensuring that the deformation ring 330 can have a preset deformation amount under the pressure of the outer layer material, ensuring the amount of the outer layer material injected in this area, thereby solving the problem of insufficient outer layer injection caused by high resistance of the inner layer, and ensuring that the inner layer embryo can form a uniform and sufficient thickness of the outer layer wall thickness under different softness conditions.

[0062] In further embodiments, the diameter of the first injection cavity 340 gradually decreases from top to bottom. During the injection process, the molten material can fill the cavity more smoothly and orderly, reducing eddy currents and bubbles. When the inner layer embryo and the inner mold 300 are removed from the first injection outer mold 100, it is more smooth. In addition, because the thickness ratio of the inner and outer layer materials is different in the axial direction, a smooth and natural color gradient layer can be formed, and the gradient effect is preserved and presented on the finished product after blow stretching, improving the artistic nature of the product.

[0063] In further embodiments, the blow injection hollow forming device for actively controlling wall thickness further comprises a first injection machine 500, a second injection machine 600 and a blow machine. The first injection outer mold 100 is installed on the first injection machine 500. The second injection outer mold 400 is installed on the second injection machine 600. The blow outer mold 200 is installed on the blow machine.

[0064] Working process:

[0065] In use, the inner mold 300 is first combined with the first injection outer mold 100, and an equal amount of molten inner layer material is injected into the first injection cavity 340 through the first injection port 101. During the above process, the force of the material on the deformation ring 330 causes the deformation ring 330 to deform slightly, and the inner layer material is slightly aggregated at the position of the deformation ring 330. After the injection is completed, the inner layer embryo is cooled, and then the inner mold 300 and the inner layer embryo formed by injection are removed from the first injection outer mold 100 and transferred to the second injection station.

[0066] The inner layer embryo is inserted into the second injection cavity 410. After the inner mold 300 is combined with the second injection outer mold 400, the outer layer material is injected into the second injection cavity 410 through the second injection port 401. During injection, the hardening degree of the inner layer embryo can be judged according to the injection pressure value displayed on the second injection machine 600, and the internal relationship is: the harder the inner layer embryo, the greater the resistance it forms to the flow of the outer layer melt, and the higher the peak injection pressure and holding pressure required by the second injection machine 600 to maintain the set injection speed. Conversely, when the inner layer embryo is soft, the actual resistance encountered by the outer layer material when flowing in the second injection cavity 410 is relatively small. Therefore, in order to maintain the set injection speed, the second injection machine 600 requires smaller peak injection pressure and subsequent holding pressure.

[0067] When the inner embryo is softer, such as Figure 6 As shown, the injection pressure generated by the second injection molding machine 600 injecting the outer layer material into the second injection cavity 410 causes a slight elastic deformation of the inner preform, thereby dissipating some energy and resulting in a small effective axial thrust transmitted to the moving shaft 351. Under the action of the compression spring 353, the moving shaft 351 only moves slightly upward or basically remains in its original position, so that the axial length of the first groove blocked by it remains almost unchanged or slightly increases, resulting in a small space for the deformation ring 330 to deform. However, in this case, the force of the outer layer material on the inner preform is concentrated at the position directly opposite the overlap of the first groove and the second groove 352. The deformation of the deformation ring 330 matches the small flow resistance brought by the softer inner layer, forming a uniform outer layer wall thickness.

[0068] When the inner layer embryo is relatively hard, such as Figure 7 As shown. During the injection of the outer layer material, the material applies radial inward pressure to the inner layer preform, and this pressure is transmitted to its inner wall through the inner layer preform itself. Since most of the inner wall of the inner layer preform, except for the area corresponding to the deformation ring 330, is rigidly supported by the first shell 321 and the second shell 322, it cannot move. Therefore, the pressure is concentrated on the bottom inner wall of the inner preform, and the second injection port 401 is located at the lower end of the second injection mold 400. The injection pressure acts directly on the lower end face of the moving shaft 351. When it overcomes the elastic force of the compression spring 353 and the gravity of the moving shaft 351, it pushes the moving shaft 351 to move upward. During the upward movement of the moving shaft 351, the length of the first groove blocked by the moving shaft 351 decreases, and the length of the first groove and the second groove 352 overlapping increases, so that the space for the deformation ring 330 to deform increases. When the length of the first groove and the second groove 352 overlapping is greater than the preset value, the force exerted by the outer material on the inner preform is sufficient to cause the inner preform and the deformation ring 330 to deform.

[0069] Furthermore, the harder the inner preform, the longer the moving shaft 351 moves, and the longer the overlap length of the first groove and the second groove 352. This ensures that under the pressure of the outer material, the deformation ring 330 can undergo a preset deformation, ensuring the amount of outer material injected into this area. This solves the problem of insufficient outer material injection caused by the high resistance of the inner layer, ensuring that the inner preform can form a uniform and sufficiently thick outer wall under different hardness conditions.

[0070] After the outer preform is injection molded, the preform body and inner mold 300 are removed from the second injection outer mold 400. During removal, the moving shaft 351 is no longer subjected to upward thrust, and the compression spring 353 provides downward thrust to the moving shaft 351, causing it to move downward and return to its original position. The preform body is then inserted into the blow molding outer mold 200, and the inner mold 300 and blow molding outer mold 200 are closed. Figure 8 As shown, after mold closing, the preform body is located in the blow molding cavity 210. High-pressure gas is injected into the air injection hole 311. The gas enters the cavity inside the mold core 320 through the air injection hole 311, and flows through the air passage on the moving shaft 351 to the through hole 323 on the peripheral wall of the second shell 322. It then flows between the inner surface of the inner mold 300 and the inner surface of the preform body, acting on the inner surface of the preform body. This causes it to expand under high pressure and adhere to the inner wall of the blow molding outer mold 200, completing the blow molding and shaping process. During blow molding, the areas where the preform body is thicker correspond to regions where the expected stretch is greater than other parts, such as the bottle shoulder.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A blow injection molding apparatus for implementing active control of wall thickness, characterized by, The inner mold can be combined with the first injection outer mold and the blow molding outer mold; The first injection outer mold has a first injection port; the inner mold comprises: A baffle is horizontally arranged, and a gas injection hole is arranged in the center of the baffle; The outer peripheral wall of the mold core has a first groove, the first groove is coaxial with the mold core, and the first groove is annular; the mold core is hollow inside and is communicated with the gas injection hole, and a plurality of through holes are arranged on the peripheral wall and are communicated inside and outside; The deformation ring is made of heat-resistant elastic material; the deformation ring is installed in the first groove; the upper and lower ends of the deformation ring are fixedly connected to the mold core; the outer surface of the deformation ring is smoothly connected to the outer peripheral wall of the mold core, and together forms the forming surface of the inner mold; When the inner mold is combined with the first injection outer mold, a first injection cavity for forming an inner layer preform is formed between the two; when the molten material is injected into the first injection cavity, the material pressure acts on the deformation ring, driving the deformation ring to produce inward elastic concave deformation, thereby increasing the wall thickness of the inner layer preform at the corresponding position; When the inner mold is combined with the blow molding outer mold, a blow molding cavity is defined between the two; The second injection outer mold has a second injection port; the inner layer preform and the outer layer preform form a preform body.

2. The injection blow hollow forming apparatus of claim 1, wherein, The inner mold further comprises an adjusting assembly for adjusting the axial length of the first groove for deformation of the deformation ring according to the hardening degree of the inner layer preform when the material is injected into the second injection cavity, so that the axial length of the first groove for deformation of the deformation ring is positively correlated with the hardness of the inner layer preform.

3. The injection blow hollow forming apparatus of claim 2, wherein, The adjusting assembly comprises a shielding piece and a compression spring; the shielding piece is movably arranged in the mold core; in the initial state, the shielding piece overlaps with the first groove by a preset length to shield the first groove; the compression spring extends vertically, and the two ends are connected to the baffle and the moving shaft, respectively.

4. The injection blow hollow forming apparatus of claim 3, wherein, The second injection port is arranged at the lower end of the second injection outer mold; the shielding piece is a moving shaft; the outer diameter of the moving shaft is equal to the inner diameter of the mold core and the inner diameter of the deformation ring; the moving shaft is slidably installed in the mold core; the moving shaft is provided with an air channel which is communicated with the gas injection hole and the through hole; the outer peripheral wall of the moving shaft is provided with a second groove; the second groove is annular; in the initial state, the upper part of the second groove overlaps with the lower part of the first groove by a preset length.

5. The injection blow molding apparatus of claim 4, wherein, The mold core comprises a first shell and a second shell; the upper end of the first shell is fixedly connected to the baffle; the second shell is coaxially arranged below the first shell; the upper and lower ends of the deformation ring are fixedly connected to the lower end of the first shell and the upper end of the second shell, respectively.

6. The injection blow molding apparatus of claim 1, wherein, The diameter of the second injection cavity gradually decreases from top to bottom.

7. The injection blow molding apparatus of claim 1, wherein, The position of the first groove and the deformation ring along the axial direction of the mold core corresponds to the area where the expected stretching amount of the molded product in the subsequent blow molding process is greater than other parts.

8. The injection blow molding apparatus of claim 1, wherein, The deformation ring is made of silicone rubber.

9. The injection blow molding apparatus of claim 1, wherein, The injection-blowing hollow forming device achieving active regulation of wall thickness further comprises a first injection molding machine, a second injection molding machine and a blowing machine; the first injection molding outer mold is installed on the first injection molding machine; the second injection molding outer mold is installed on the second injection molding machine; and the blowing outer mold is installed on the blowing machine.

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