A needle valve structure for solving glue overflow and glue dropping

Abstract

The utility model relates to the field of point gum, specifically discloses a needle valve structure solving glue overflow and glue dropping, the inside installation of valve body has the stroke seat and the striker, and the stroke seat links up with the striker, one end of stroke seat is fixed with one end of striker, the other end of striker moves in the chamber of valve body, installs the needle head at the glue outlet of valve body, the other end of striker has the concave sealing surface, the distance from the concave sealing surface of striker to one end of needle head is the stroke of striker, and the stroke of striker matches the stroke of stroke seat, ensure that the concave sealing surface can fully tighten the end of needle head, through the combination design of lengthened stroke seat, concave striker, foolproof nut and coating needle head, combine diaphragm pump + vacuum defoaming feeding mode, solve the problem of hanging glue, glue overflow and glue dropping in the small dose high frequency point gum scene. Can promote the glue precision and stability of valve, improve the point gum quality and production efficiency in the field of microelectronic packaging, and be applicable to the trace precision point gum scene of humidity curing glue.

Description

Technical Field

[0001] This utility model belongs to the field of dispensing, and in particular relates to a needle valve structure for solving the problem of glue overflow and dripping. Background Technology

[0002] Current needle valve technology has three major technical shortcomings in precision dispensing applications: 1) Sealing failure issue: Traditional needle valves cannot achieve a complete micron-level seal when closed. A gap exists between the valve needle and the valve seat, causing adhesive to slowly leak out after the valve is closed. The longer the interval, the more the adhesive surface dries, affecting subsequent adhesive dispensing. Unstable dispensing from the needle valve impacts product quality and can lead to product scrap. For Peters series moisture-curing adhesives, a sealing force exceeding 20N is required to effectively prevent adhesive leakage.

[0003] 2) Problem of air content in glue: The positive pressure feeding system (air pressure > 0.2MPa) causes the air content of the glue to increase by more than 35%. When high frequency dispensing, the air bubbles precipitated at the needle tip form an air resistance effect, causing dispensing breakpoints or unstable spraying.

[0004] 3) Surface tension effect: Most of the glue residue at the needle tip is due to the high surface tension between the glue and the needle tip. The glue residue that overflows from the needle tip dries faster in the humid curing environment, causing blockage. Utility Model Content

[0005] This invention relates to the field of fluid dispensing equipment technology, and specifically provides a systematic solution to the problems of glue residue, overflow, and dripping that occur in low-dose, high-frequency dispensing scenarios for moisture-curing adhesives (such as Peters series adhesives). This technology is mainly applied to precision PCB coating and can significantly improve dispensing quality and production efficiency in the microelectronics packaging field.

[0006] The technical solution provided by this utility model is as follows: A needle valve structure for solving the problem of glue overflow and dripping includes a valve body, inside which a stroke seat and a striking pin are installed, the stroke seat being linked with the striking pin; one end of the stroke seat is fixed to one end of the striking pin, and the other end of the striking pin moves within the cavity of the valve body; a needle is installed at the glue outlet of the valve body; the other end of the striking pin has a concave sealing surface, the distance from the concave sealing surface of the striking pin to one end of the needle is the striking pin stroke, and the striking pin stroke matches the stroke of the stroke seat; ensuring that the concave sealing surface can fully press against the end of the needle.

[0007] Preferably, the concave sealing surface of the firing pin has a cone angle of 120° and a concave depth of 0.4 mm.

[0008] Preferably, it also includes a needle mounting base, one end of which is fixed to the dispensing port of the valve body, and the needle is mounted on the inner wall of the other end of the needle mounting base.

[0009] Preferably, the outer wall of the needle mounting base is provided with a nut with a foolproof positioning structure.

[0010] Preferably, the needle is a Teflon-coated needle with a hydrophobic coating on its surface.

[0011] Preferably, it also includes a diaphragm pump and a vacuum degassing machine, wherein the vacuum degassing machine is connected to the glue tank through a glue inlet pipe, the vacuum degassing machine is connected to the feed end of the diaphragm pump through a glue outlet pipe, and the discharge end of the diaphragm pump is connected to the feed port of the dispensing valve.

[0012] Advantages compared to existing technologies: 1. Improved sealing performance: The thickened travel seat and the recessed design of the striker work together to enhance the sealing force when the valve is closed through a mechanical structure, preventing adhesive leakage. The foolproof nut ensures consistent assembly and avoids seal failure due to installation errors. After the valve is closed, the striker and needle are completely sealed. Under air pressure, the adhesive at the needle tip is held in place, preventing it from leaking out. 2. Bubble control: Instead of using positive pressure feeding, a diaphragm pump combined with a vacuum degassing system is employed to reduce the air content in the adhesive from the source. This, along with a valve sealing design, prevents air bubbles from forming and overflowing during high-frequency dispensing. The adhesive undergoes degassing treatment before placement. The innovative feeding system, employing a combination of a diaphragm pump and a vacuum degassing machine, achieves a degassing rate of up to 95% in the adhesive. 3. Anti-adhesion mechanism: The hydrophobicity of the Teflon-coated needle reduces the surface tension between the adhesive and the needle, thus reducing adhesive residue. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments or prior art, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a cross-sectional view of the overall structure of this utility model; Figure 2 This is a schematic diagram of the firing pin structure of this utility model; Figure 3 This is a schematic diagram of the nut of this utility model; Figure 4 This is a schematic diagram of the needle of this utility model; According to the above diagram: travel seat - 1; nut - 2; firing pin - 3; needle - 4; Detailed Implementation

[0015] To facilitate understanding of this utility model, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings show preferred embodiments of this utility model. However, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this utility model.

[0016] It should be noted that when a component is described as being "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is described as being "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "fixed," "integral," "left," "right," and similar expressions used in this specification are for illustrative purposes only, and in the figures, structurally similar units are labeled with the same reference numerals.

[0017] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention.

[0018] like Figure 1-4 As shown, one embodiment of this utility model is: a needle valve structure for solving the problem of glue overflow and dripping, including a valve body, a stroke seat 1 and a striking pin 3 are installed inside the valve body, the stroke seat 1 and the striking pin 3 are linked; one end of the stroke seat 1 is fixed to one end of the striking pin 3, and the other end of the striking pin 3 moves within the cavity of the valve body; a needle 4 is installed at the glue outlet of the valve body; the other end of the striking pin 3 has a concave sealing surface, the distance from the concave sealing surface of the striking pin 3 to one end of the needle 4 is the striking pin stroke, and the striking pin stroke matches the stroke of the stroke seat 1; ensuring that the concave sealing surface can fully press against the end of the needle 4.

[0019] The concave sealing surface of the firing pin 3 has a cone angle of 120° and a concave depth of 0.4mm.

[0020] It should be noted that: Stroke seat 1: When in the valve-closed position, it drives the concave sealing surface of the striker 3 to form a surface contact with the end of the needle 4 and apply sufficient sealing force to achieve a complete seal. For example, the length of stroke seat 1 is increased (e.g., by 0.6 mm) to provide sufficient stroke to ensure that the concave sealing surface can fully press against the end of the needle 4, deepening the internal structure to ensure that the striker 3 completely presses against the needle 4 at the zero point position when the valve is closed, preventing glue leakage.

[0021] Furthermore, the shape design of the striking pin 3 is changed: the flat-bottomed striking pin 3 is changed to a concave structure with a depth of 0.4mm and an angle of 120°, which reduces the contact area with the needle 4 and increases the pressure to improve the sealing performance, increasing the contact pressure by 300% (the sealing force of the traditional flat-bottomed striking pin is 12N → the concave structure reaches 36N). The length of the striking pin 3 can be extended according to customer needs: extending the length of the striking pin 3 enhances the fit between the striking pin 3 and the needle 4 when the valve is closed, ensuring a complete seal.

[0022] In this embodiment, a needle mounting base is also included. One end of the needle mounting base is fixed to the dispensing port of the valve body, and the needle 4 is mounted on the inner wall of the other end of the needle mounting base. The outer wall of the needle mounting base is provided with a nut 2 with a foolproof positioning structure.

[0023] It should be noted that the nut 2 with the foolproof positioning structure is used to ensure the repeatability of the installation position of the needle 4; for example, the nut 2 structure extends by 1.2mm and is equipped with a foolproof positioning structure to ensure that different operators can accurately position the nozzle to the same position when installing it, thus ensuring assembly accuracy.

[0024] In the embodiment: the needle 4 is a Teflon-coated needle with a hydrophobic coating on the surface. The Teflon-coated needle has low surface energy, which reduces the influence of the surface tension of the adhesive. Its hydrophobicity reduces adhesive adhesion and prevents the needle 4 from getting stuck with adhesive.

[0025] In this embodiment, a diaphragm pump and a vacuum degassing machine are also included. The vacuum degassing machine is connected to the glue tank via an inlet pipe and to the feed end of the diaphragm pump via an outlet pipe. The discharge end of the diaphragm pump is connected to the inlet of the dispensing valve. The needle valve anti-sticking and dripping process uses a diaphragm pump + vacuum degassing method and sets high-frequency dispensing parameters (valve opening time 5ms, valve closing time 20ms) to ensure the stability of high-frequency dispensing with small glue volumes.

[0026] By combining a diaphragm pump (pressure <0.05MPa) and a vacuum degassing machine (vacuum degree -95kPa), the bubble elimination rate is 95%. Positive pressure feeding is not used to avoid gas being forced into the glue, resulting in excessive air content. This also prevents the impact of the ejector pin 3 into the glue in high-frequency mode, which could generate bubbles and create air resistance, affecting the glue dispensing status.

[0027] Correct installation and operation steps for needle valves: 1) First, turn the travel seat 1 counterclockwise until it is fully open, then you can remove the old needle. 2) Install the new needle and fully tighten the nut (foolproof structure). Note that the needle and the nut should not rotate at the same time. 3) Then turn the travel seat 1 clockwise to close it tightly; 4) Perform zeroing operation. When the air valve is opened, the supply air pressure is turned on, and the limit position is when the fluid stops flowing out.

[0028] 5) Finally, adjust to the target stroke (e.g., 10 strokes).

[0029] This technical solution addresses the issues of glue residue, overflow, and dripping in low-dose, high-frequency dispensing scenarios by combining an extended stroke seat 1, a concave impact pin 3, a foolproof nut 2, and a coated needle 4 with a diaphragm pump and vacuum degassing feeding method. It improves the valve's dispensing accuracy and stability, enhances dispensing quality and production efficiency in the microelectronics packaging field, and is suitable for micro-precision dispensing scenarios using moisture-curing adhesives.

[0030] It should be noted that the above-mentioned technical features can be combined with each other to form various embodiments not listed above, all of which are considered to be within the scope of this utility model specification; and, for those skilled in the art, improvements or modifications can be made based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims of this utility model.

Claims

1. A needle valve structure for solving the problem of glue overflow and dripping, comprising a valve body, characterized in that; The valve body is internally equipped with a stroke seat and a striker, the stroke seat being linked to the striker; one end of the stroke seat is fixed to one end of the striker, and the other end of the striker moves within the cavity of the valve body; a needle is installed at the outlet of the valve body; the other end of the striker has a concave sealing surface, the distance from the concave sealing surface of the striker to one end of the needle is the striker stroke, and the striker stroke matches the stroke of the stroke seat; ensuring that the concave sealing surface can fully press against the end of the needle.

2. The needle valve structure for solving the problem of glue overflow and dripping according to claim 1, characterized in that; The concave sealing surface of the firing pin has a cone angle of 120° and a concave depth of 0.4 mm.

3. The needle valve structure for solving the problem of glue overflow and dripping according to claim 1, characterized in that; It also includes a needle mounting base, one end of which is fixed to the dispensing port of the valve body, and the needle is mounted on the inner wall of the other end of the needle mounting base.

4. The needle valve structure for solving the problem of glue overflow and dripping according to claim 3, characterized in that; The outer wall of the needle mounting base is provided with a nut with a foolproof positioning structure.

5. The needle valve structure for solving the problem of glue overflow and dripping according to claim 1 or 3, characterized in that; The needle is a Teflon-coated needle with a hydrophobic coating on its surface.

6. The needle valve structure for solving the problem of glue overflow and dripping according to claim 1, characterized in that; It also includes a diaphragm pump and a vacuum degassing machine. The vacuum degassing machine is connected to the glue tank through a glue inlet pipe. The vacuum degassing machine is connected to the feed end of the diaphragm pump through a glue outlet pipe. The discharge end of the diaphragm pump is connected to the feed port of the dispensing valve.

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