Core rod assembly with stable blowing function in injection blow molding machine
By setting a rectangular air outlet hole and a rectangular annular breathable insert in the mandrel assembly, combined with the precise positioning of the rectangular exhaust and the wedge-shaped surface design, the problems of poor sealing effect between the mandrel head and the mandrel body and the unsatisfactory exhaust effect of the breathable insert are solved, and high-precision positioning and stable blowing functions are achieved, ensuring the successful injection and product quality.
Patent Information
- Application Number
- CN202421875479.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-05
- Publication Date
- 2025-06-03
- Estimated Expiration
- 2034-08-05
AI Technical Summary
In the existing mandrel assembly, the sealing effect between the mandrel head and the mandrel body is poor, resulting in the failure of the injection; at the same time, the exhaust effect of the breathable insert is not ideal, and it is easy to form bubble pits in the plastic tube blank, affecting the beauty and quality of the product.
A rectangular air outlet is provided in the mandrel body, and a rectangular annular breathable insert and a rectangular exhaust member are sealed therein. The breathable insert and the rectangular exhaust element achieve precise positioning through the wedge surface and the limit ring table. The four surfaces of the rectangular exhaust element jointly bear the rotational torque to reduce the risk of wear; the rectangular shoulders and rectangular ring design of the breathable insert improve the exhaust speed and effect.
Through precise positioning and rectangular design, the sealing effect between the mandrel head and the mandrel body and the exhaust effect of the breathable insert are improved, and the injection failure and the formation of bubble pits are avoided, ensuring the quality and aesthetics of the product.
Smart Images
Figure CN222933325U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of blow molding, in particular to a mandrel assembly with a stable air blowing function in an injection blow molding machine. Background Art
[0002] The mandrel assembly in an injection blow molding machine is an important component, mainly acting on the blow molding of hollow plastic products. The mandrel assemblies on the market currently include: a mandrel body, a mandrel head, a guide sleeve, a thimble, a mandrel compression spring, and a star nut. The mandrel body is a hollow structure, with a through airway inside it. The front end of the airway is an air inlet, and the rear end is an air outlet. The mandrel head is inserted into the rear end of the mandrel body to block the air outlet. The guide sleeve is slidably arranged in the air outlet and connected to the mandrel head. An exhaust groove is arranged on the guide sleeve. The thimble is inserted inside the airway and connected to the guide sleeve. The star nut is connected to the mandrel ejector rod. The mandrel compression spring is sleeved on the mandrel ejector rod. A number of inlaid holes are arranged at circumferential intervals on the mandrel head, and air-permeable inlaid parts are arranged in the inlaid holes. During preform injection, the molten plastic is extruded and wrapped around the mandrel head of the mandrel assembly and the rear end of the mandrel body through a preform mold to form a plastic preform. During the extrusion and wrapping process, the air between the plastic preform and the mandrel assembly can enter the air outlet, airway, and air inlet through the air-permeable inlaid parts and then be discharged outward. During blow molding, the thimble is pushed, and the mandrel head and the mandrel body are separated through the guide sleeve to form an air outlet gap. Compressed air enters the plastic preform through the air inlet, airway, air outlet, and air outlet gap to blow mold the plastic preform until it is formed.
[0003] The existing mandrel assembly has the following defects: First, since the cross-sections of the air outlet in the mandrel body, the mandrel head, and the guide sleeve in the existing mandrel assembly are all circular, when the molten plastic is extruded and wrapped around the mandrel assembly, due to the flow of the molten plastic, uneven forces will be generated on the mandrel head, resulting in the rotation of the mandrel head. When the mandrel head rotates, it will rub against the mandrel body, thereby reducing the sealing effect between the two. In order to prevent the mandrel head and the mandrel body from rotating, generally, flat surfaces are milled on the inner wall of the air outlet of the mandrel body and on the guide sleeve. When the mandrel head rotates under the action of the molten plastic, the milled surfaces between the guide sleeve and the air outlet interact to play a limiting role. However, since only this one surface is subjected to the rotational torque, it is easy to wear. After wear, it is easy for the mandrel body and the mandrel head to be misaligned and unable to achieve precise positioning, which will lead to the failure of preform injection. Second, in order to ensure the strength of the mandrel head, it is necessary to strictly control the size and spacing of the air-permeable inlaid parts. This will reduce the exhaust effect of the air-permeable inlaid parts. During preform injection, it is easy for the air in the preform mold to not be completely discharged through the air-permeable inlaid parts, and air is likely to remain between the mandrel assembly and the plastic preform. This is likely to form bubble pits on the inner side wall of the plastic preform, and ultimately form uneven pits on the inner surface of the blow-molded bottle, affecting the appearance and quality of the product. Summary of the Utility Model
[0004] The purpose of the present utility model is to provide a mandrel assembly with a stable blowing function in an injection-blowing machine that can maintain high-precision positioning between the mandrel body and the mandrel head and can stabilize the compressed air for blow molding.
[0005] To achieve the above purpose, the technical solution adopted by the present utility model is: a mandrel assembly with a stable blowing function in an injection-blowing machine, including: a mandrel body, a mandrel head, a thimble, a compression spring, and a star-shaped nut. An air inlet hole, an air passage, and a rectangular air outlet hole penetrating through the left and right ends of the mandrel body are provided in the mandrel body. A rectangular ring-shaped air-permeable insert is hermetically arranged in the rectangular air outlet hole. A first wedge surface and a second wedge surface are provided on the right end wall of the air-permeable insert. A third wedge surface that cooperates with the first wedge surface of the air-permeable insert is provided on the left end wall of the mandrel head. A rectangular exhaust member is hermetically and movably clamped in the rectangular air outlet hole. A rectangular diffusion cavity is left between the rectangular exhaust member and the air-permeable insert. A plurality of exhaust grooves are evenly distributed on the outer side wall of the rectangular exhaust member that fits with the inner side wall of the rectangular air outlet hole. A fourth wedge surface that cooperates with the second wedge surface is provided on the rectangular exhaust member. The rectangular exhaust member is connected to the mandrel head. The thimble is movably inserted into the air passage of the mandrel body and then connected to the rectangular exhaust member. The compression spring is sleeved on the thimble and is located in the air inlet hole. The star-shaped nut is threadedly connected to the thimble and presses against the compression spring.
[0006] Further, in the mandrel assembly with a stable blowing function in the aforementioned injection-blowing machine, a rectangular shoulder is provided on the air-permeable insert. The air-permeable insert is inserted into the large-diameter end of the rectangular air outlet hole and is in interference fit with it. The shoulder on the air-permeable insert abuts against the mandrel body.
[0007] Further, in the mandrel assembly with a stable blowing function in the aforementioned injection-blowing machine, an air groove is left between the left end wall of the rectangular exhaust member and the rectangular air outlet hole.
[0008] Further, in the mandrel assembly with a stable blowing function in the aforementioned injection-blowing machine, a weight-reducing mounting hole is provided in the mandrel head. The rectangular exhaust member is inserted into the weight-reducing mounting hole and is in interference fit with it. A limiting ring platform extends upward on the rectangular exhaust member. The fourth wedge surface is provided on the limiting ring platform. The limiting ring platform on the rectangular exhaust member abuts against the mandrel head.
[0009] Further, in the mandrel assembly with a stable blowing function in the aforementioned injection-blowing machine, a weight-reducing hole is provided in the rectangular exhaust member.
[0010] Further, in the mandrel assembly with a stable blowing function in the aforementioned injection-blowing machine, a circle of diffusion grooves is provided between the exhaust grooves and the limiting ring platform.
[0011] The advantages of the present utility model are as follows: a rectangular air outlet is provided in the mandrel body, and a rectangular exhaust member connected to the mandrel head is hermetically and movably clamped in the rectangular air outlet. During billet injection, when the molten plastic applies a rotational torque to the mandrel head, the four surfaces of the rectangular exhaust member jointly bear the rotational torque, reducing the rotational torque borne by each surface, thereby ensuring that it is not easy for wear to occur between the rectangular exhaust member and the rectangular air outlet, and thus ensuring the positioning accuracy between the mandrel head and the air-permeable insert on the mandrel body. Then, the positioning accuracy between the mandrel body and the mandrel head is ensured through the precise positioning among the mandrel head, the rectangular exhaust member, and the air-permeable insert; the rectangular ring-shaped air-permeable insert provided on the mandrel body can improve the exhaust speed and effect during billet injection, preventing damage to the plastic pipe billet extruded on the mandrel assembly caused by residual air; a number of exhaust grooves are evenly distributed on the outer side wall of the rectangular exhaust member that fits the inner side wall of the rectangular air outlet. The evenly distributed exhaust grooves can evenly disperse the compressed air, balance the air flow pressure in each exhaust groove, and enable it to flow stably. A rectangular diffusion cavity is left between the rectangular exhaust member and the air-permeable insert, and the air flow velocity is reduced through the air flow in the diffusion exhaust grooves to ensure the uniformity of the air flow, thereby ensuring that the plastic pipe billet can be stably blow-molded. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 FIG. is a three-dimensional structural schematic diagram of a mandrel assembly with a stable blowing function in the injection blow molding machine described in the present utility model.
[0013] Figure 2 is Figure 1 the schematic diagram of the plane cross-sectional structure in
[0014] Figure 3 is Figure 2 the three-dimensional cross-sectional structural schematic diagram of the mandrel body in
[0015] Figure 4 is Figure 2 the three-dimensional cross-sectional structural schematic diagram of the mandrel head in
[0016] Figure 5 is Figure 2 the three-dimensional cross-sectional structural schematic diagram of the air-permeable insert in
[0017] Figure 6 is Figure 2 the three-dimensional cross-sectional structural schematic diagram of the rectangular exhaust member in DETAILED DESCRIPTION OF THE EMBODIMENTS
[0018] The technical solution of the present utility model will be further described below in conjunction with the drawings and preferred embodiments.
[0019] As shown in Figures 1 to 6As described above, the mandrel assembly with a stable air blowing function in the injection blow molding machine of the present utility model includes: a mandrel body 1, a mandrel head 2, a thimble 3, a compression spring 4, and a star nut 5. An air inlet hole 11, an air passage 12, and a rectangular air outlet hole 13 that penetrate through the left and right ends of the mandrel body 1 are provided in the mandrel body 1. A rectangular ring-shaped air permeable insert 6 is hermetically arranged in the rectangular air outlet hole 13. A rectangular shoulder 61 is provided on the air permeable insert 6. The air permeable insert 6 is snapped into the large-diameter end of the rectangular air outlet hole 13 and is in interference fit with it. The rectangular shoulder 61 on the air permeable insert 6 abuts against the mandrel body 1. A first wedge surface 62 and a second wedge surface 63 are provided on the right end wall of the air permeable insert 6. A third wedge surface 21 that cooperates with the first wedge surface 62 of the air permeable insert 6 is provided on the left end wall of the mandrel head 2. A weight-reducing mounting hole 22 is provided in the mandrel head 2. A rectangular exhaust member 7 is provided in the weight-reducing mounting hole 22 in an interference fit manner, which can not only be installed with the rectangular exhaust member 7 but also reduce the weight. A weight-reducing hole 71 is provided in the rectangular exhaust member 7 to reduce the weight of the rectangular exhaust member 7. A limiting ring platform 72 extends upward on the rectangular exhaust member 7. The limiting ring platform 72 abuts against the mandrel head 2. A fourth wedge surface 73 that cooperates with the second wedge surface 63 of the air permeable insert 6 is provided on the limiting ring platform 72. The rectangular exhaust member 7 is hermetically and movably snapped into the rectangular air outlet hole 13 of the mandrel body 1. A rectangular diffusion cavity 64 is left between the rectangular exhaust member 7 and the air permeable insert 6. An air groove 14 is left between the rectangular exhaust member 7 and the left end wall of the rectangular air outlet hole 13. A plurality of exhaust grooves 74 are evenly distributed on the outer side wall of the rectangular exhaust member 7 that is in contact with the inner side wall of the rectangular air outlet hole 13. A diffusion groove 75 is provided in a circle between the exhaust groove 74 and the limiting ring platform 72. The thimble 3 movably passes through the air inlet hole 11 and the air passage 12 of the mandrel body 1 and is connected to the rectangular exhaust member 7. The compression spring 4 is sleeved on the thimble 3 and is located in the air inlet hole 11. The star nut 5 is threadedly connected to the thimble 3 and presses against the compression spring 4.
[0020] During injection molding, the ejector pin 3 drives the rectangular exhaust part 7 and the mandrel head 2 to abut against the breathable insert 6 under the elastic force of the compression spring 4. The third wedge surface 21 on the mandrel head 2 is in sealing contact with the first wedge surface 62 on the breathable insert 6, and the fourth wedge surface 73 on the rectangular exhaust part 7 is in sealing contact with the second wedge surface 63 on the breathable insert 6. The mandrel head 2 and the rectangular exhaust part 7 block the rectangular air outlet 13. The double-layer sealing contact structure can improve the positioning accuracy between the mandrel body 1 and the mandrel head 2. The molten plastic is extruded around the mandrel body 1 and the mandrel head 2. Since the rectangular ring-shaped breathable insert 6 is a complete circle, the breathable area is increased. During the extrusion process, the air in the injection mold can quickly enter the rectangular diffusion cavity 64 and the diffusion groove 75 through the rectangular ring-shaped breathable insert 6, and then be discharged into the air groove 14 through the exhaust groove 74 on the rectangular exhaust part 7. In this way, there will be no residual air damaging the plastic pipe blank when it is extruded around the mandrel body 1 and the mandrel head 2. Moreover, during injection molding, since the four outer side walls of the rectangular exhaust part 7 cooperate with the four inner side walls of the rectangular air outlet 13, when the molten plastic acts on the mandrel body 1 and the mandrel head 2, the four surfaces on the rectangular exhaust part 7 jointly bear the rotational torque, reducing the rotational torque borne by each surface, so as to ensure that it is not easy to wear between the rectangular exhaust part 7 and the rectangular air outlet 13, and thus ensure the precise positioning between the mandrel head 2 and the breathable insert 6 on the mandrel body 1.
[0021] During the blow molding process, after the ejector pin 3 is stressed, it overcomes the elastic force of the compression spring 4 and drives the rectangular exhaust part 7 and the mandrel head 2 to move to the right and no longer block the rectangular air outlet 13. An air outlet annular gap is formed between the rectangular exhaust part 7 and the breathable insert 6 and between the mandrel head 2 and the breathable insert 6. The volume of the air groove 14 between the rectangular exhaust part 7 and the rectangular air outlet 13 increases. Compressed air enters the rectangular air outlet 13 from the air inlet hole 11 and the air duct 12. Since the volume of the air groove 14 increases, after the compressed air enters the air groove 14 from the air duct 12, the flow rate will decrease due to the increased space and form a relatively stable air flow. The air flow in the air groove 14 will evenly enter each exhaust groove 74 in the rectangular exhaust part 7. Each exhaust groove 74 stabilizes the air flow, making the air flow pressure in each exhaust groove 74 balanced, avoiding the situation of unstable air flow caused by uneven pressure. Then the air flow is evenly transported from each exhaust groove 74 to the rectangular diffusion cavity 64 and the diffusion groove 75 for diffusion, further improving the uniformity of the air flow by reducing the air flow dead angle. Finally, the air flow enters the plastic pipe blank from the annular air outlet gap and blows the plastic pipe blank into shape.
[0022] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model and are not intended to limit it. Although the present utility model has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent substitutions can still be made to the specific implementation manners of the present utility model, and any modification or equivalent substitution that does not depart from the spirit and scope of the present utility model shall be covered within the protection scope of the claims of the present utility model.
Claims
1. A core rod assembly with a stable blowing function in an injection blow molding machine, including: A core rod body, a core rod head, a ejector pin, a compression spring and a star nut, characterized in that: an air inlet hole, an air duct and a rectangular air outlet hole are provided in the core rod body and pass through the left and right ends of the core rod body; a rectangular annular air-permeable insert is sealed in the rectangular air outlet hole; a first wedge-shaped surface and a second wedge-shaped surface are provided on the right end wall of the air-permeable insert; a third wedge-shaped surface matching the first wedge-shaped surface of the air-permeable insert is provided on the left end wall of the core rod head; a rectangular exhaust is provided in the rectangular air outlet hole for sealing the movable card A rectangular diffusion cavity is reserved between the rectangular exhaust member and the breathable insert, a plurality of exhaust grooves are evenly distributed on the outer wall of the rectangular exhaust member which is in contact with the inner wall of the rectangular air outlet, a fourth wedge-shaped surface which matches the second wedge-shaped surface is arranged on the rectangular exhaust member, the rectangular exhaust member is connected to the core rod head, the ejector pin is movably arranged in the air passage of the core rod body and then connected to the rectangular exhaust member, the compression spring is sleeved on the ejector pin and is located in the air inlet, and the star nut is threadedly connected to the ejector pin and pressed against the compression spring.
2. The core rod assembly with stable blowing function in the injection blow molding machine according to claim 1, characterized in that: A rectangular convex shoulder is arranged on the air-permeable insert, which is inserted into the large-diameter end of the rectangular air outlet hole and has an interference fit therewith, and the convex shoulder on the air-permeable insert abuts against the core rod body.
3. The core rod assembly with stable blowing function in the injection blow molding machine according to claim 1, characterized in that: An air groove is reserved between the rectangular exhaust member and the left end wall of the rectangular air outlet.
4. The core rod assembly with stable blowing function in the injection blow molding machine according to claim 1, characterized in that: A weight-reducing mounting hole is provided in the core rod head, a rectangular exhaust member is inserted into the weight-reducing mounting hole and has an interference fit therewith, a limiting ring platform is provided on the rectangular exhaust member extending upward, a fourth wedge-shaped surface is provided on the limiting ring platform, and the limiting ring platform on the rectangular exhaust member rests on the core rod head.
5. The core rod assembly with stable blowing function in the injection blow molding machine according to claim 4, characterized in that: A weight-reducing hole is provided in the rectangular exhaust member.
6. The core rod assembly with stable blowing function in the injection-blow molding machine according to claim 4, characterized in that: A circle of diffusion grooves is arranged between the exhaust groove and the limiting ring platform.