Retrusive demolding runner-free injection mold for medical negative pressure ball internal thread assembly

Abstract

The utility model discloses a medical negative pressure ball internal thread assembly retreating demolding runner-free injection mold which comprises a front mold and a rear mold, and the front mold comprises a heat insulation plate, a fixed mold seat plate, a hot runner mounting plate and a front mold core plate which are sequentially laminated; the rear mold comprises a rear mold core plate, a first mold plate, an oil cylinder mounting mold plate, a second mold plate and a movable mold seat plate which are sequentially laminated, the bottom of the rear mold core plate is connected with a mold top roller, and a mold core transmission shaft which rotates and reciprocates is arranged in the rear mold; one end of the mold core transmission shaft extends into a cavity between the front mold insert and the rear mold insert and is connected with a threaded mold core, the other end of the mold core transmission shaft is connected with a rotary reciprocating assembly, and a driving assembly is arranged in the sky side direction of the oil cylinder mounting template. According to the scheme, when the internal thread of the product is demoulded, the thread core can be retreated for demoulding, the product is kept still, and the internal thread of the product can be effectively protected from being damaged.

Description

Technical Field

[0001] This utility model belongs to the field of mold technology, specifically relating to a retractable demolding, runnerless injection mold for a medical negative pressure ball internal thread assembly. Background Technology

[0002] Medical negative pressure bulbs are widely used in surgical and clinical drainage procedures, primarily to provide a continuous and stable negative pressure environment for drainage devices, thereby assisting in the drainage of fluids or secretions. In practical applications, medical negative pressure bulbs typically need to be connected to drainage devices or other components via connecting tubes, and their interfaces often employ threaded structures to ensure a secure and airtight connection.

[0003] Currently, the internal thread components of medical negative pressure balls are mostly integrally molded using injection molding, in conjunction with a mold. In traditional molds, after the internal thread is formed, the product is demolded by rotating the threaded core in place, directly pushing the product forward to eject it. This makes the internal thread susceptible to twisting and damage, easily causing thread damage or product deformation, affecting the quality of the finished product and its assembly performance. Utility Model Content

[0004] To address the aforementioned problems, this utility model provides a retractable, runnerless injection mold for a medical negative pressure ball internal thread assembly, comprising a front mold and a rear mold. The front mold includes a heat insulation plate, a fixed mold base plate, a hot runner mounting plate, and a front mold core plate stacked sequentially. The front mold incorporates a needle valve-type hot runner structure. A sprue bushing is located at the sprue of the needle valve-type hot runner structure in the front mold core plate. A nested front mold insert is located below the sprue bushing. The rear mold includes a rear mold core plate, a first template, a cylinder mounting template, a second template, and a moving mold base plate stacked sequentially. A rear mold insert matching the front mold insert is nested on the rear mold core plate. A cavity is formed between the front mold insert and the rear mold insert. The bottom of the rear mold core plate is connected to... The injection molding machine has an injection molding machine top roller. The rear mold is equipped with a core drive shaft that rotates and reciprocates. One end of the core drive shaft extends into the cavity between the front mold insert and the rear mold insert and is connected to a threaded core. The other end of the core drive shaft is connected to a rotary reciprocating assembly. The hydraulic cylinder is mounted on the top side of the template and is equipped with a drive assembly. The drive assembly drives the rotary reciprocating assembly to rotate and reciprocate. A ejector pin is fixed on the moving mold base plate. The ejector pin passes through the rotary reciprocating assembly, the core drive shaft, and is coaxially arranged with the inner ring of the threaded core. The gate bushing, the front mold insert, the rear mold insert, the threaded core, and the ejector pin form a product cavity after the mold is closed.

[0005] Preferably, the rotary reciprocating assembly includes a coupling seat, an output gear is connected to the outer circumferential surface of the coupling seat, an external thread structure is provided at the bottom of the coupling seat, and a coiled nut is fixedly provided on the second template, the external thread structure being threadedly connected to the coiled nut.

[0006] Preferably, the drive assembly includes a drive cylinder, a rack, a first transmission gear, and a second transmission gear. The output end of the drive cylinder is connected to a double-sided T-slot member, one end of which is connected to the rack. The first transmission gear and the second transmission gear are coaxial and rotatably mounted on the cylinder mounting template. The rack meshes with the first transmission gear, and the second transmission gear meshes with the output gear.

[0007] Preferably, the cylinder mounting template has rack wear plates on both the upper and lower sides in the direction of rack movement.

[0008] Preferably, the cylinder mounting template has a rack guide bearing located on one side of the rack plane.

[0009] Preferably, the first template is internally fitted with a core drive shaft guide bearing, which is slidably sleeved on the outside of the core drive shaft.

[0010] Preferably, a limiting bolt is locked on the first template, and a clearance groove is provided at the bottom of the front mold core plate. The limiting bolt passes through the rear mold core plate and extends into the clearance groove of the front mold core plate.

[0011] Preferably, the side of the front mold insert is provided with limiting ribs.

[0012] The advantages of this utility model are:

[0013] 1. This solution utilizes a rotatable, retractable threaded core, coupled with a guide bearing for limiting movement, to allow the threaded core to retract during demolding, ensuring the product remains stationary. The product is then ejected after the core is removed. This effectively prevents thread damage, deformation, or tearing caused by forced rotation during ejection. It is particularly suitable for demolding high-precision internal threads in elastic material products such as medical negative pressure balls, ensuring assembly accuracy and sealing performance.

[0014] 2. This solution employs a needle valve-type hot runner structure, featuring precise temperature control and valve needle flow control. This ensures constant temperature flow of molten plastic during injection molding, effectively preventing runner solidification issues caused by temperature fluctuations. Multi-component nozzles and independent cylinders control the opening / closing of the gate, achieving efficient and synchronous control of multi-cavity molds, significantly improving product quality and injection molding stability.

[0015] 3. This design utilizes a hydraulic cylinder to drive a rack and pinion transmission rotating assembly, with the injection molding machine's ejection and return mechanisms providing the power source to achieve synchronous rotation and axial movement of the core. The entire mechanism is compact and reliable in transmission. Combined with limit bolts, guide bearings, and wear-resistant plates on the rack, it ensures smooth operation of each component, reduces frictional loss, and extends mold life. Furthermore, the rational distribution of functional components facilitates disassembly, assembly, and routine maintenance, contributing to long-term stable operation in industrial production. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view of the overall structure of this utility model.

[0017] Figure 2 This is a schematic diagram of the threaded core and coupling seat structure of this utility model.

[0018] Figure 3 This is a structural diagram of the hydraulic cylinder installation template for this utility model.

[0019] Figure 4 This is a side view of the hydraulic cylinder mounting template of this utility model.

[0020] Figure 5 This is a structural diagram of the connection between the drive cylinder and the rack of this utility model.

[0021] Figure 6 This is a schematic diagram of the slider needle valve type hot runner structure of this utility model.

[0022] Figure 7 This is a bottom view of the front mold insert of this utility model.

[0023] In the diagram: heat insulation plate 105, fixed mold base plate 106, hot runner mounting plate 107, front mold core plate 104, sprue bushing 102, front mold insert 103, rear mold insert 201, rear mold core plate 204, rear mold insert pressure plate 205, threaded core 202-1, core drive shaft 202-2, coupling seat 202-3, external thread structure 202-4, core drive shaft guide bearing 206, bearing pressure plate 208, first template 207, cylinder mounting template 210, drive cylinder 217, rack; 218, first transmission gear; 216, second transmission gear; output gear; 209, rack wear plate; 223, rack guide bearing; 224, coiled nut; 212, second template; 213, ejector pin; 203, ejector pin pressure block; 214, double-sided T-slot component; 219, micro switch; 225, first mounting plate; 222, second mounting plate; 221, third mounting plate; 220, limit bolt; 226, moving mold base plate; 215, mold top roller; 301, guide post; 302. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0025] In the description of this utility model, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0026] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," and "connected," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Simultaneously, when an component is referred to as "fixed to" or "equipped on" another component, it can be directly on the other component or may have an intervening component present. When an component is referred to as "connected to" another component, it can be directly connected to the other component or may have an intervening component present. When an component is referred to as "fixedly connected to" another component, it can be a common fixed connection method such as welding, bolting, or gluing. In short, those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0027] Example 1, as Figure 1 As shown, a medical negative pressure ball internal thread assembly retractable demolding channelless injection mold includes a front mold and a rear mold. The front mold includes a heat insulation plate 105, a fixed mold base plate 106, a hot runner mounting plate 107 and a front mold core plate 104 stacked in sequence. The front mold is equipped with a needle valve type hot runner mechanism. During the process of molten plastic being injected from the injection molding machine nozzle until it flows into the product cavity, the temperature is controlled by the needle valve type hot runner mechanism, so that the molten plastic always maintains a constant temperature and a molten state, and no runner solidification is generated.

[0028] Combination Figure 6The needle valve type hot runner mechanism includes a main nozzle 1011, a manifold 1012, and a sub-nozzle 1013. Each of the main nozzle 1011, manifold 1012, and sub-nozzle 1013 has a heating and temperature control element and interconnected melt channels. The sub-nozzle 1013 extends through the front mold core plate 104 to the gate. A cylinder 1014 is located above the sub-nozzle 1013 in the fixed mold base plate 106. The output end of the cylinder 1014 is connected to a valve needle 1015, which extends through the corresponding manifold 1012 to the sub-nozzle 1013, reaching the gate to control its opening and closing. The main nozzle 1011 contacts the injection molding machine nozzle ball head, and the melt flows through the main nozzle 1011, manifold 1012, and sub-nozzle 1013 into the product cavity. The number of nozzles 1013, cylinders 1014 and valve needles 1015 in the needle valve hot runner mechanism is usually set to multiple, matching the number of cavity gates, so that multiple cavity gates can be opened and closed at the same time.

[0029] In combination Figure 1 The front mold core plate 104 has a gate bushing 102 located at the gate of the needle valve hot runner structure. Below the gate bushing 102 is a nested front mold insert 103. The rear mold includes a rear mold core plate 204, a first template 207, a cylinder mounting template 210, a second template 213, and a moving mold base plate 215 stacked sequentially. A rear mold insert 201, matching the front mold insert 103, is nested on the rear mold core plate 204. A rear mold insert pressure plate 205 abuts against the bottom plane of the rear mold insert 201 and is bolted to the rear mold core plate 204. A cavity is formed between the front mold insert 103 and the rear mold insert 201, communicating with the gate. The bottom of the rear mold core plate 204 is bolted to a mold top roller 301. A spring is fitted on the mold top roller 301, enabling product ejection and spring-forced reset of the rear mold core plate 204. Figure 7 The front mold insert 103 has four limiting ribs on its side, which form a groove around the molded internal thread product. The combination of the two can prevent the molded internal thread product from rotating when demolding.

[0030] Combination Figure 2 The rear mold has a reciprocating core drive shaft 202-2. One end of the core drive shaft 202-2 extends into the cavity between the front mold insert 103 and the rear mold insert 201 and connects to a threaded core 202-1. A ejector pin 203 is fixed on the moving mold base plate 215. The ejector pin 203 is fixed to the moving mold base plate 215 by an ejector pin pressure block 214. The ejector pin 203 passes through the reciprocating assembly, the core drive shaft 202-2, and is coaxially arranged with the inner ring of the threaded core 202-1. The end of the ejector pin 203 near the threaded core 202-1 forms the core of the product's inner contour. Figure 1As shown, after the front mold and rear mold are closed, the sprue bushing 102, the front mold insert 103, the rear mold insert 201, the threaded core 202-1, and the ejector pin 203 together form a complete product cavity. Among them, the sprue bushing 102, the front mold insert 103, and the rear mold insert 201 form the outer contour cavity of the product, while the threaded core 202-1 and the ejector pin 203 form the internal thread and the remaining inner contour cavity of the product.

[0031] The other end of the core drive shaft 202-2 is connected to a rotary reciprocating assembly. A drive assembly is located on the top side of the cylinder mounting template 210. The drive assembly drives the rotary reciprocating assembly to rotate and reciprocate, which in turn drives the core drive shaft 202-2 and the threaded core 202-1 to rotate and reciprocate. Specifically, the rotary reciprocating assembly includes a coupling seat 202-3. An output gear 209 is connected to the outer circumferential surface of the coupling seat 202-3. An external thread structure 202-4 is located at the bottom of the coupling seat. A threaded nut 212 is fixed to the second template 213 by screws. The external thread structure 202-4 is threadedly connected to the threaded nut 212. The thread pitch of the external thread structure 202-4 is consistent with the thread pitch of the threaded core 202-1 to avoid damaging the product.

[0032] When the coupling seat 202-3 rotates, it moves axially under the action of the coiled nut 212. The first template 207 is internally fitted with a core drive shaft guide bearing 206, which is slidably sleeved on the outside of the core drive shaft 202-2. The core drive shaft guide bearing 206 guides and positions the threaded core 202-1 as it moves in and out of the product cavity. The bearing pressure plate 208 abuts against the bottom plane of the bearing and is locked onto the first template 207 by bolts.

[0033] like Figure 3-5 As shown, the drive assembly includes a drive cylinder 217, a rack 218, a first transmission gear 216, and a second transmission gear 211. The output end of the drive cylinder 217 is connected to a double-sided T-slot member 219. One end of the double-sided T-slot member 219 is connected to the rack 218. The double-sided T-slot member 219 is slidably disposed between two third mounting plates 220 on both sides. The lugs of the double-sided T-slot member 219 are located between the third mounting plates 220 on the left and right sides and the second mounting plates 221 on the upper and lower sides. A first mounting plate 222 is provided on the side of the double-sided T-slot member 219 closest to the drive cylinder 217. The third mounting plates 220, second mounting plates 221, and first mounting plates 222 are screwed together to form a whole and fixed together on the cylinder mounting template 210, providing guidance and limiting for the double-sided T-slot member 219.

[0034] Combination Figure 3-4The second transmission gear 211 and the first transmission gear 216 are coaxial and arranged vertically, rotating together on the cylinder mounting template 210. The rack 218 meshes with the first transmission gear 216, and the second transmission gear 211 meshes with the output gear 209. The drive cylinder 217 drives the double-sided T-slot component 219 to pull or reset the rack 218. The stroke is controlled by the microswitches 225 on both sides. The translation of the rack 218 drives the first transmission gear 216 and the second transmission gear 211 to rotate simultaneously, driving the output gear 209 on the coupling seat 202-3 to rotate, ultimately realizing the entry and exit of the threaded core 202-1 into and out of the cavity.

[0035] Combination Figure 3 Inside the cylinder mounting template 210, on both the upper and lower sides along the direction of movement of the rack 218, there are rack wear plates 223. These wear plates 223 are made of self-lubricating and wear-resistant materials such as copper alloy or polyoxymethylene. The wear plates 223 serve to position and guide the linear movement of the rack 218, and also reduce frictional wear, thus extending the service life of the rack 218. Inside the cylinder mounting template 210, on one side of the rack 218 plane, there is a rack guide bearing 224, ensuring the rack 218 moves linearly and reciprocally from the side.

[0036] like Figure 1 As shown, a limiting bolt 226 is locked on the first template 207. The bottom of the front mold core plate 104 is provided with a clearance groove. The limiting bolt 226 passes through the rear mold core plate 204 and extends into the clearance groove of the front mold core plate 104, thereby limiting the ejection of the rear mold core plate 204.

[0037] The principle behind this solution is as follows: after the current mold and the rear mold are joined, if... Figure 1As shown, injection molding is initiated, and molten plastic is injected into the product cavity through a needle valve-type hot runner structure. After injection molding, valve needle 1015 controls the closure of each gate. After the product cools and solidifies, the front mold and rear mold separate. The parting line PL1 opens by 2mm to release pressure. Due to its internal thread structure, the product remains on the rear mold side. Opening the parting line PL1 by 2mm prevents excessive pressure in the mold cavity, facilitating smooth thread retraction and core removal. Then, the drive cylinder 217 begins thread retraction and core removal. The threaded core 202-1 rotates and retracts, separating from the product, which remains stationary in the mold. After thread retraction, the parting line PL1 is fully open, and the injection molding machine begins to eject the mold ejector roller 301 and the rear mold core plate 204, ejecting the product. At this time, the spring is compressed, and the parting line PL2 opens until the rear mold core plate 204 reaches the limit bolt 226. After the parting line PL2 is fully open, the product is completely ejected, completing demolding from the parting line PL1. After demolding, the ejector force of the injection molding machine is released, the spring force is released, and the mold ejector roller 301 is driven by the spring force to retract and reset the mold core plate 204. The parting line PL2 then closes, and the drive cylinder 217 drives the threaded core 202-1 to reset to the cavity. After that, the front and rear molds close, and the parting line PL1 closes. The mold closing is completed, and the valve needle 1015 controls the opening of each gate, and the next injection cycle begins. The moving mold base plate 215 is fixed with guide pillars 302, which extend upward into the front mold core plate 104, and guide the mold ejector roller 301 to eject and reset the mold core plate 204.

[0038] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A medical negative pressure ball internal thread assembly back-off demolding without runner injection mold, characterized by: The mold includes a front mold and a rear mold. The front mold includes a heat insulation plate (105), a fixed mold base plate (106), a hot runner mounting plate (107), and a front mold core plate (104) stacked in sequence. The front mold is provided with a needle valve type hot runner structure. A gate bushing (102) is provided at the gate of the needle valve type hot runner structure in the front mold core plate (104). A front mold insert (103) nested with the gate bushing (102) is provided below it. The rear mold... The mold assembly includes a rear mold core plate (204), a first template (207), a hydraulic cylinder mounting template (210), a second template (213), and a moving mold base plate (215) stacked sequentially. A rear mold insert (201) matching the front mold insert (103) is nested on the rear mold core plate (204). A cavity is formed between the front mold insert (103) and the rear mold insert (201). A mold top roller (301) is connected to the bottom of the rear mold core plate (204). A core drive shaft (202-2) for rotary reciprocating movement is provided in the rear mold. One end of the core drive shaft (202-2) extends into the cavity between the front mold insert (103) and the rear mold insert (201) and is connected to a threaded core (202-1). The other end of the core drive shaft (202-2) is connected to a rotary reciprocating assembly. A drive assembly is provided on the top side of the hydraulic cylinder mounting template (210). The component drives the rotary reciprocating component to rotate and reciprocate. The moving mold base plate (215) is fixed with a screw (203). The screw (203) passes through the rotary reciprocating component, the core drive shaft (202-2) and the inner ring of the threaded core (202-1) and is coaxially arranged. The gate bushing (102), the front mold insert (103), the rear mold insert (201), the threaded core (202-1) and the screw (203) form the product cavity after the mold is closed.

2. The medical negative pressure female threaded component back-out ejection without runner injection mold of claim 1, wherein: The rotary reciprocating assembly includes a coupling seat (202-3), an output gear (209) is connected to the outer circumferential surface of the coupling seat (202-3), and an external thread structure (202-4) is provided at the bottom of the coupling seat (202-3). A coiled nut (212) is fixed on the second template (213), and the external thread structure (202-4) is threadedly connected to the coiled nut (212).

3. The medical negative pressure female threaded component back-out ejection without runner injection mold of claim 2, wherein: The drive assembly includes a drive cylinder (217), a rack (218), a first transmission gear (216), and a second transmission gear (211). The output end of the drive cylinder (217) is connected to a double-sided T-slot member (219). One end of the double-sided T-slot member (219) is connected to the rack (218). The first transmission gear (216) and the second transmission gear (211) are coaxial and rotatably mounted on the cylinder mounting template (210). The rack (218) meshes with the first transmission gear (216), and the second transmission gear (211) meshes with the output gear (209).

4. The medical negative pressure female threaded component back-out ejection without runner injection mold of claim 3, wherein: The cylinder mounting template (210) is provided with rack wear plates (223) on both the upper and lower sides in the direction of movement of the rack (218).

5. The medical negative pressure female threaded component back-out ejection without runner injection mold of claim 4, wherein: The cylinder mounting template (210) has a rack guide bearing (224) located on one side of the rack (218) plane.

6. The medical negative pressure female threaded component back-out ejection without runner injection mold of claim 5, wherein: The first template (207) is internally fitted with a core drive shaft guide bearing (206), which is slidably sleeved on the outside of the core drive shaft (202-2).

7. The medical negative pressure female threaded component back-out ejection without runner injection mold of claim 6, wherein: The first template (207) is locked with a limiting bolt (226), and the bottom of the front mold core plate (104) is provided with a clearance groove. The limiting bolt (226) passes through the rear mold core plate (204) and extends into the clearance groove of the front mold core plate (104).

8. The medical negative pressure female threaded component back-out ejection without runner injection mold of claim 7, wherein: The side of the front mold insert (103) is provided with limiting ribs.

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