Middle sleeve used in air ejector for plastic molds

Abstract

This utility model discloses a middle sleeve for an air ejector in plastic molds, belonging to the field of plastic mold manufacturing technology. The middle sleeve is a truncated cone-shaped structure with varying diameters, extending through both ends, and is positioned between the traditional center ejector and the air ejector sleeve, forming a three-layer combined air ejector structure: air ejector sleeve - middle sleeve - center ejector. The middle sleeve achieves uniform force transmission and precise guidance of the ejection process through a precise fit between its inner inclined surface and the outer wall of the center ejector, and a sliding fit between its outer inclined surface and the inner wall of the air ejector sleeve. Simultaneously, the bottom surface of the middle sleeve fits against the stepped surface of the air ejector sleeve, enhancing the stability of the overall structure and providing precise axial positioning for the return spring. The core of this utility model lies in fundamentally solving the problems of ejection jamming and poor return caused by uneven air output in existing two-layer air ejector structures through the introduction of the middle sleeve, significantly improving the reliability of the air ejector operation and the ejection quality of plastic products.

Description

Technical Field

[0001] This utility model relates to the field of plastic mold manufacturing technology, specifically to an air ejector structure for a plastic mold ejection system, and more particularly to a middle sleeve applied to the air ejector of a plastic mold. Background Technology

[0002] Air ejectors are key functional components in plastic molds for demolding plastic parts. Compared to traditional ejection mechanisms such as ejector pins and ejector plates, air ejectors, powered by compressed air, offer advantages such as uniform ejection force distribution, rapid response, and compact structure. They can effectively shorten mold manufacturing cycles, reduce steel consumption, and lower production costs.

[0003] During installation and use, the air ejector needs to have air channels of a specified diameter pre-machined on the mold template, and then be pressed into the assembly using soft tools such as copper or wooden hammers. After assembly, it is essential to ensure that the ejector end face of the air ejector maintains a very high degree of flatness with the mold cavity surface, and that all moving parts are tightly fitted together to avoid movement jamming or wear caused by improper clearance.

[0004] Currently, the industry commonly uses a two-layer combined air ejector structure of "center top - air ejector sleeve," supplemented by springs to achieve the reset function after ejection. In this structure, the center top is precision ground to ensure accurate dimensions and a smooth surface. It is typically fixed by a cylindrical pin below the center ejector rod or by a threaded connection at the bottom. However, this existing structure reveals significant defects in practical applications: due to machining errors, wear, and the influence of air path layout, the distribution of compressed air in the fit gap between the center top and the air ejector sleeve is difficult to be absolutely uniform, resulting in the center top experiencing asymmetrical lateral forces during ejection. This uneven force easily causes the center top to tilt or shift slightly during movement, interfering with the inner wall of the air ejector sleeve, ultimately leading to ejection jamming, reset failure, and even damage to the plastic part or mold, severely impacting production automation and product yield. Utility Model Content

[0005] To address the shortcomings of the existing technology, the purpose of this invention is to provide a middle sleeve for air ejectors in plastic molds. This middle sleeve, through an innovative three-layer structure design, aims to effectively eliminate the influence of lateral forces caused by uneven air output, ensuring stable and smooth axial ejection and repositioning of the center ejector under any operating condition. This fundamentally solves the ejection jamming problem and improves the reliability of mold operation.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A middle sleeve for air ejectors in plastic molds is an axially continuous double-beveled variable-diameter truncated cone-shaped structure. Its core innovation lies in being set between the traditional center top and the air ejector sleeve, thus forming a brand-new three-layer combined air ejector structure of "air ejector sleeve-middle sleeve-center top".

[0008] The specific shape features, functions, and assembly relationships of the middle sleeve are as follows:

[0009] The upper surface is the annular plane at the top of the middle sleeve. Its function is to form a continuous and flat mold cavity surface together with the top of the center top and the top of the air ejector sleeve after assembly, ensuring that it does not affect the molding of the plastic part.

[0010] To further explain, after the product is assembled, the upper surface is coplanar with the center top and the top of the air cap.

[0011] Inner inclined surface: This is a continuous conical inclined surface on the inner wall of the middle sleeve. Its inclination is precisely calculated to perfectly match the inclination of the outer wall of the central top. Its core function is to evenly transfer the jacking force on the central top to the middle sleeve, and to automatically compensate for the asymmetrical force acting on the central top due to uneven air output by utilizing its inclined surface matching characteristics, thus converting the lateral component force into a stable axial thrust and neutralizing the force imbalance.

[0012] To further explain, the inner inclined surface is a continuous inner conical surface that matches the slope of the outer wall of the central top.

[0013] Outer inclined surface: This is a smooth conical inclined surface on the outer wall of the middle sleeve. Its inclination is precisely matched with the inclination of the inner wall of the air cap sleeve to form a sliding pair. Its core function is to provide precise guiding constraints for the axial movement of the entire middle sleeve and strictly limit its radial degree of freedom, thereby preventing the middle sleeve from causing any axial deviation of its internal central top and fundamentally avoiding the risk of jamming.

[0014] To further explain, the outer inclined surface is a smooth outer conical surface that matches the inclination of the inner wall of the gas cap sleeve.

[0015] Inner hole: A straight, round hole that passes through the center of the sleeve. Its function is to provide an independent, undisturbed linear motion channel for the auxiliary ejector pins in the mold, ensuring the normal functioning of the ejector pins.

[0016] To explain further, the inner hole is a straight hole that passes through the middle sleeve, forming the movement channel of the push rod.

[0017] The middle end face is an annular transition surface connecting the inner inclined surface and the inner hole inside the middle sleeve. It has a dual function: first, it serves as a structural reinforcement surface, enhancing the overall rigidity of the middle sleeve and preventing elastic deformation of the inner inclined surface under stress; second, during assembly, it fits against the stepped surface of the center top to achieve axial positioning, ensuring that the inner hole of the middle sleeve coincides with the axis of the center top and the push rod.

[0018] Bottom surface: This is the annular plane at the bottom of the middle sleeve. Its function is crucial: Firstly, in the assembled state, it fits closely to the top stepped surface inside the air crown sleeve, greatly enhancing the radial stability of the middle sleeve within the air crown sleeve and preventing wobbling.

[0019] To further explain, the fit between the bottom end face and the stepped surface of the gas spring sleeve is used to enhance the radial stability of the middle sleeve, while providing precise axial positioning and support for the upper end of the return spring.

[0020] Compared with the prior art, the present invention has the following significant advantages:

[0021] Excellent anti-jamming performance: Through the double-sloping guide and force compensation design of the middle sleeve, the direct sliding of the central top in the traditional two-layer structure is transformed into the buffer and guide of the middle sleeve, which effectively absorbs and counteracts the lateral force generated by uneven air pressure, making the ejection and resetting actions extremely smooth.

[0022] Extremely high ejection stability: The middle sleeve, as an intermediate transmission and guide component, greatly increases the guide length and contact area of ​​the moving parts, making the movement trajectory of the center top more stable, and the ejection process is free from shaking and deviation.

[0023] Extended service life: Uniform force transmission and precise guidance reduce localized wear on the contact surfaces of the center jack, air jack sleeve, and the middle sleeve itself, thereby extending the service life of the entire air jack device.

[0024] Easy maintenance: The three-layer modular structure is clearly designed. During maintenance, the middle sleeve and the center top can be removed as sub-components for easy inspection, cleaning or replacement. Attached Figure Description

[0025] Figure 1 : Axonometric structural diagram of the middle sleeve described in this utility model.

[0026] Figure 2 : A schematic diagram of the assembly of the middle sleeve and the central top of this utility model.

[0027] Figure 3 : A cross-sectional schematic diagram of the present invention applied to a complete air-cushion device.

[0028] Figure 4 Schematic diagram of the cross-section of the gas cap sleeve.

[0029] Figure 5 : Schematic diagram of the bottom surface of the air cap sleeve.

[0030] Explanation of the labels in the diagram:

[0031] 1: Middle sleeve; 11: Upper end face; 12: Inner bevel; 13: Outer bevel; 14: Inner hole; 15: Middle end face; 16: Bottom end face;

[0032] 2: Center top; 21: Locking hole;

[0033] 3: Air-jacking sleeve; 30: Top step surface; 31: Lower end face; 32: Inner wall of the air-jacking sleeve; 33: Radial straight groove

[0034] 4: Spring. Detailed Implementation

[0035] The specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0036] See Figure 3 The complete air-jacking device provided by this utility model has the following assembly sequence: First, the middle sleeve 1 is fitted onto the central push rod of the central top 2. Then, the central push rod of the central top 2 is inserted into the inner hole of the air-jacking sleeve 3, so that the inner inclined surface 12 of the middle sleeve 1 fits against the outer wall of the central top 2, and the middle end face 15 of the middle sleeve 1 is tightly positioned against the corresponding stepped surface of the central top 2. The return spring 4 is fitted into the central push rod of the central top 2, and the upper part of the return spring 4 contacts the lower end face 31 of the air-jacking sleeve 3. Then, the horizontal pin is inserted from the radial straight groove 33 of the air-jacking sleeve into the locking hole 21 of the central top 2 or a threaded nut is made below the central push rod of the central top to fix it, thereby positioning the spring 4 and preventing the central top 2 from coming out under air pressure.

[0037] The above description is merely a preferred embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in this utility model, based on the technical solution and concept of this utility model, should be included within the protection scope of this utility model.

Claims

1. A middle sleeve applied to a gas knockout of a plastic mold, characterized in that, The middle sleeve (1) is an axially continuous double-beveled variable-diameter truncated frustum structure, located between the central top (2) and the air top sleeve (3); the middle sleeve (1) comprises, from top to bottom: The upper end face (11) is an annular plane, which is coplanar with the top of the center top (2) and the top of the air cap sleeve (3) after assembly; The inner inclined surface (12) is a continuous inner conical surface that matches the slope of the outer wall of the central top (2); The outer inclined surface (13) is a smooth outer conical surface that matches the inclination of the inner wall (32) of the gas cap sleeve; The inner hole (14) is a straight hole that passes through the middle sleeve, forming the movement channel of the push rod; The middle end face (15) is an annular transition surface connecting the inner inclined surface (12) and the inner hole (14), which is used to fit and position with the stepped surface of the center top (2); The bottom end face (16) is an annular plane, which is used to fit the top step surface of the gas crown sleeve (3).

2. The bushing for use in a gas knockout of a plastic mold according to claim 1, wherein The inner inclined surface (12) and the outer wall of the center top (2) are used to uniformly transmit the top force and compensate for the force imbalance.

3. The bushing for use in a gas knockout of a plastic mold according to claim 1, wherein The sliding fit between the outer inclined surface (13) and the inner wall of the air top sleeve (3) provides precise guidance for the axial movement of the middle sleeve (1) and the center top (2), preventing the movement axis from deviating.

4. The bushing for use in a gas knockout of a plastic mold according to claim 1, wherein The fit between the bottom end face (16) and the stepped surface of the gas sleeve (3) is used to enhance the radial stability of the middle sleeve (1) and at the same time provide precise axial limiting and support for the upper end of the return spring (4).

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