Injection head structure capable of preventing molten glue from flowing back

Abstract

The utility model discloses a injection head structure that can prevent the melt glue from flowing back, which comprises a glue blocking head and a movable blocking ring, wherein the movable blocking ring is provided with blocking ring through holes, the glue blocking head comprises a head part, a glue blocking part and a connecting part, the head part can be put on the movable blocking ring, the glue blocking part can block the inner cavity of the cylinder, and the connecting part can be connected with the screw rod, the glue blocking part through holes, which can pass the melt glue, are arranged axially on the glue blocking part, the movable blocking ring is movably sleeved on the head part, the movable blocking ring covers the glue blocking part through holes when covering the glue blocking part, and a limiting spring is connected on the head part, and the limiting spring pushes the movable blocking ring against the end face of the glue blocking part. The utility model has the advantages that the movable blocking ring is pushed against the end face of the glue blocking part by the elasticity of the spring, active glue blocking is realized, and the effective sealing is formed in the initial stage and low pressure stage of the melt glue injection, so that the melt glue backflow is completely eliminated, and the sealing assembly is provided with continuous and stable initial pre-tightening force.

Description

Technical Field

[0001] This utility model relates to the technical field of screw sealing structure for injection molding machines, and more particularly to an injection head structure that can prevent molten adhesive backflow. Background Technology

[0002] Currently, the mainstream screw sealing structure for injection molding machines generally adopts a common fork-type or ring-type "three-part" design: a glue head, a glue ring, and a glue spacer. This traditional structure performs adequately with conventional plastics, but it reveals several inherent defects when dealing with high-flow-rate plastics such as PA, liquid silicone, and PET, as well as in high-precision injection molding or long-term continuous production conditions: Insufficient sealing performance: Relying on the back pressure of the molten plastic itself to form a seal, the sealing effect is poor for low-viscosity plastics, easily leading to molten backflow; Rapid wear and short lifespan: The components rely on sliding friction, and micro-rotation easily occurs under molten pressure, causing uneven wear and frequent replacements; Unstable injection endpoint: Due to backflow and wear, the endpoint position of each injection, i.e., the holding pressure start point, fluctuates, directly affecting product weight and dimensional accuracy, causing quality problems such as insufficient glue and shrinkage; High maintenance costs: Frequent downtime for replacements and losses from producing defective products result in high overall maintenance costs. Therefore, the existing screw sealing structure for injection molding machines needs further improvement. Summary of the Invention

[0003] The technical problem to be solved by this utility model is to provide an injection head structure that has a good sealing effect and effectively prevents the backflow of molten glue, in view of the above-mentioned existing technology.

[0004] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows: an injection head structure that can prevent molten glue backflow, including a glue-blocking head that can be connected to the end of the injection molding machine screw and a movable retaining ring that can pass through the molten glue. The movable retaining ring has through holes. The glue-blocking head includes a head through which the movable retaining ring can pass, a glue-blocking part that can block the inner cavity of the barrel, and a connecting part that can connect to the screw. The glue-blocking part has an axial through hole that can pass through the glue-blocking part. The movable retaining ring can be moved back and forth on the head relative to the head. When the movable retaining ring covers the glue-blocking part, the movable retaining ring covers the through hole of the glue-blocking part. The feature is that a limit spring is connected to the head, and the limit spring pushes the movable retaining ring against the end face of the glue-blocking part.

[0005] As an improvement, the end of the head may preferably be provided with a limiting protrusion, the limiting spring is sleeved on the head, one end of the limiting spring abuts against the limiting protrusion, and the other end of the limiting spring abuts against the movable retaining ring.

[0006] In a further improvement, the root of the head may preferably be provided with a limiting section with a regular hexagonal cross section, and the central through hole of the movable retaining ring is a hexagonal hole adapted to the limiting section, and the movable retaining ring is fitted on the limiting section.

[0007] In a further improvement, the head may preferably include a central shaft and a limiting sleeve fitted on the central shaft, the limiting protrusion being disposed at the end of the limiting sleeve, and the limiting spring being fitted on the limiting sleeve.

[0008] In a further improvement, the limiting protrusion can preferably be a limiting disc, the limiting spring contacts one end face of the limiting disc, and an anti-collision hemisphere is provided on the other end face of the limiting disc.

[0009] As a further improvement, both sides of the hemisphere can preferably be provided with spherical recesses that facilitate gripping and installation.

[0010] As an improvement, the retaining ring through hole can preferably be an arc-shaped waist-shaped hole.

[0011] As an improvement, the through holes in the adhesive resisting section can preferably be evenly distributed on the circumference of the adhesive resisting section.

[0012] As an improvement, a tapered section that can improve the smoothness of material discharge can preferably be provided between the adhesive blocking part and the connecting part.

[0013] As an improvement, an annular groove that can prevent stress concentration in the connection part can preferably be provided on the connection part.

[0014] Compared with existing technologies, the advantages of this invention are as follows: A limiting spring is connected to the head, which presses the movable retaining ring against the end face of the adhesive-blocking part. The spring's own elasticity ensures active sealing, rather than relying on passive back pressure. This allows for effective sealing during the initial injection and low-pressure stages, completely preventing molten adhesive backflow and providing a continuous and stable initial preload for the sealing assembly. Furthermore, a hexagonal limiting section at the root of the head fundamentally prevents circumferential rotation of the movable retaining ring during operation, transforming uneven rotational wear into uniform axial wear. This significantly improves the assembly's lifespan and sealing stability, and substantially reduces... The cost of spare parts procurement and production losses due to downtime for replacements are reduced. The head end is equipped with a limit protrusion, which strictly defines the maximum compression stroke of the spring and the range of motion of the movable retaining ring, preventing excessive spring compression. This avoids plastic deformation and elasticity failure caused by the spring being under extreme compression for a long time, ensuring long-term stability of the sealing performance. Simultaneously, it ensures consistent movement of the movable retaining ring in each injection action, thus guaranteeing process repeatability. This results in stable sealing, eliminating the need for frequent adjustments after production parameters are set, and shortening start-up and material changeover times. Stable sealing reduces abnormal scouring and wear of the screw and barrel by the backflow melt, extending the service life of the core components. In summary, this injection head structure is not a simple improvement on the traditional three small parts, but a structural and fundamental upgrade. Through three major innovations—"spring active sealing," "anti-rotation structure," and "mechanical limit protection"—it constructs a more intelligent, reliable, and durable sealing system. It directly solves the sealing problem that has long plagued the injection molding industry. Especially in high-end, precision, and high-efficiency production scenarios, the quality improvement, cost savings, and stability assurance it brings will create significant economic benefits and competitive advantages for enterprises. Attached Figure Description

[0015] Figure 1 This is a perspective view of an embodiment of the present utility model;

[0016] Figure 2 for Figure 1 A three-dimensional image from another angle;

[0017] Figure 3 yes Figure 1 A frontal projection view;

[0018] Figure 4 yes Figure 3 Cross-sectional view along line AA;

[0019] Figure 5 yes Figure 4 A schematic diagram of a structure that displays the injection status within the inner cavity of the barrel;

[0020] Figure 6 yes Figure 1 Exploded structural diagram;

[0021] Figure 7 yes Figure 6 A structural breakdown diagram from another perspective. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0023] like Figures 1 to 7 As shown, the injection head structure in this embodiment that prevents molten glue backflow includes a glue-blocking head that can be connected to the end of the injection molding machine screw and a movable retaining ring 2 that allows molten glue to pass through. The movable retaining ring 2 has retaining ring through holes 21. The glue-blocking head includes a head through which the movable retaining ring 2 can pass, a glue-blocking part 1 that can block the inner cavity 41 of the barrel 4, and a connecting part 13 that can connect to the screw. The glue-blocking part 1 has a glue-blocking part through hole 14 that allows molten glue to pass through. The movable retaining ring 2 can be moved back and forth on the head. When the movable retaining ring 2 covers the glue-blocking part 1, the movable retaining ring 2 covers the glue-blocking part through hole 14. A limit spring 3 is connected to the head, and the limit spring 3 pushes the movable retaining ring 2 against the end face of the glue-blocking part 1.

[0024] The head has a limiting protrusion 15 at its end, and a limiting spring 3 is fitted onto the head. One end of the limiting spring 3 contacts the limiting protrusion 15, and the other end of the limiting spring 3 contacts the movable retaining ring 2. The root of the head has a limiting section 16 with a regular hexagonal cross-section. The central through hole of the movable retaining ring 2 is a hexagonal hole that matches the limiting section 16, and the movable retaining ring 2 is fitted onto the limiting section 16.

[0025] The head includes a central shaft 11 and a limiting sleeve 12 fitted on the central shaft 11. The limiting protrusion 15 is provided at the end of the limiting sleeve 12, and the limiting spring 3 is fitted on the limiting sleeve 12. The outer diameter of the limiting sleeve 12 is larger than the diameter of the through hole in the middle of the movable retaining ring 12.

[0026] The limiting protrusion 15 is a limiting disc, and the limiting spring 3 contacts one end face of the limiting disc. An anti-collision hemisphere 151 is provided on the other end face of the limiting disc. Both sides of the hemisphere 151 are provided with spherical recesses for easy gripping and installation.

[0027] The retaining ring through hole 21 is an arc-shaped, waist-shaped hole. The adhesive-blocking through holes 14 are evenly distributed on the circumference of the adhesive-blocking part 1. A tapered section 17 is provided between the adhesive-blocking part 1 and the connecting part 13 to improve the smoothness of material discharge. An annular groove 131 is provided on the connecting part 13 to prevent stress concentration in the connecting part 13.

Claims

1. An injection head structure capable of preventing molten adhesive backflow, comprising a blocking head that can be connected to the end of an injection molding machine screw and a movable retaining ring (2) through which molten adhesive can pass, wherein the movable retaining ring (2) has retaining ring through holes (21), the blocking head comprising a head through which the movable retaining ring (2) can pass, a blocking part (1) capable of blocking the inner cavity (41) of the barrel, and a connecting part (13) capable of connecting to the screw, wherein the blocking part (1) has an axially arranged blocking part through hole (14) through which molten adhesive can pass, the movable retaining ring (2) being able to move back and forth relative to the head and being fitted onto the head, wherein when the movable retaining ring (2) covers the blocking part (1), the movable retaining ring (2) covers the blocking part through hole (14), characterized in that: A limiting spring (3) is connected to the head, and the limiting spring (3) pushes the movable retaining ring (2) against the end face of the adhesive blocking part (1).

2. The injection head structure according to claim 1, characterized in that: The head has a limiting protrusion (15) at its end. The limiting spring (3) is sleeved on the head. One end of the limiting spring (3) contacts the limiting protrusion (15), and the other end of the limiting spring (3) contacts the movable retaining ring (2).

3. The injection head structure according to claim 2, characterized in that: The head has a limiting section (16) with a regular hexagonal cross section at its root. The middle through hole of the movable retaining ring (2) is a hexagonal hole that matches the limiting section (16). The movable retaining ring (2) is fitted onto the limiting section (16).

4. The injection head structure according to claim 3, characterized in that: The head includes a central shaft (11) and a limiting sleeve (12) fitted on the central shaft (11). The limiting protrusion (15) is provided at the end of the limiting sleeve (12), and the limiting spring (3) is fitted on the limiting sleeve (12).

5. The injection head structure according to claim 4, characterized in that: The limiting protrusion (15) is a limiting disk, the limiting spring (3) touches one end face of the limiting disk, and an anti-collision hemisphere (151) is provided on the other end face of the limiting disk.

6. The injection head structure according to claim 5, characterized in that: Both sides of the hemisphere (151) are provided with spherical recesses that facilitate gripping and installation.

7. The injection head structure according to any one of claims 1 to 6, characterized in that: The retaining ring through hole (21) is an arc-shaped waist-shaped hole.

8. The injection head structure according to any one of claims 1 to 6, characterized in that: The through holes (14) of the adhesive barrier are evenly distributed on the circumference of the adhesive barrier (1).

9. The injection head structure according to any one of claims 1 to 6, characterized in that: A tapered section (17) is provided between the adhesive blocking part (1) and the connecting part (13) to improve the smoothness of material discharge.

10. The injection head structure according to any one of claims 1 to 6, characterized in that: An annular groove (131) is provided on the connecting part (13) to prevent stress concentration in the connecting part (13).

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