Assembly method for prefilled syringe

Abstract

An assembly method for a prefilled syringe. The prefilled syringe comprises: a barrel (1), a needle hub (2), a needle (3), a protective cover (4) and a needle cap (5), wherein stop hooks (402), which radially contract inwards and are used for pushing up a proximal end face of the needle hub (2), are provided at a proximal end of the protective cover (4). The assembly method comprises the following steps: S01, sleeving the needle cap (5) on the needle hub (2), and using a camera to confirm whether the needle cap has been pierced by the needle; S02, inserting a sleeve pressing head (6) into the protective cover (4) so as to radially push up the stop hooks (402) outwards, wherein the minimum inner diameter of the sleeve pressing head is greater than the maximum outer diameter of the needle cap; S03, sleeving on the needle hub the protective cover into which the sleeve pressing head has been inserted; and S04, removing the sleeve pressing head from the protective cover. In the assembly method for a prefilled syringe, a sleeve is used to open the protective cover from the inside out, thus avoiding the risk of the protective cover possibly getting stuck in the needle cap or the needle hub when the protective cover is subsequently mounted; that is, the needle cap is mounted first, and a camera is used to check whether the needle cap has been pierced, and then the protective cover is mounted.

Description

Method for assembling a prefilled syringe Technical Field

[0001] The invention belongs to the technical field of medical devices, and in particular relates to an assembling method of a prefilled syringe. Background Art

[0002] Prefilled syringes are injection devices used in the medical field that integrate the functions of a syringe and a medication container. These syringes are pre-filled with medication during the manufacturing process and sealed to protect the drug's purity and effectiveness. This pre-filled design makes use more convenient and quicker for medical staff, reducing the time and steps required for medication preparation. Furthermore, because prefilled syringes are single-use, they avoid the risk of cross-infection and enhance patient safety. Furthermore, strict sealing measures are implemented during the manufacturing process to effectively protect the drug's purity and stability, extending its shelf life.

[0003] The main components of a prefilled syringe include the syringe body, medication container, piston, needle, and protective cap. The syringe body is typically made of transparent material, allowing medical personnel to clearly observe the dosage and status of the medication solution. The medication container is typically made of glass or plastic, with a capacity tailored to the needs, allowing for different dosages of medication. The piston pushes the medication into the needle for injection. The needle then delivers the medication into the patient. The protective cap protects the needle before and after use.

[0004] However, existing prefilled syringes are often discarded after use, leaving the needle exposed and dangerous. To address this issue, operators often replace the removed protective cap. However, this approach has many drawbacks. First, the protective cap is custom-made for the needle, with a small opening, making it difficult to reinsert after removal. Second, the reinstallation process can easily result in the needle pricking the operator's hand.

[0005] To solve the above problems, a protective prefilled syringe with a protective cover has been proposed on the market. The inventor has previously applied for an invention patent in the related field, specifically CN114642793A, a prefilled syringe with a front shield. The protective cover can adjust the axial position by pushing and pulling, which is used to expose the needle to complete the injection, and to cover the needle and discard it after the injection is completed to avoid needle sticks to others.

[0006] Regarding the assembly method of the prefilled syringe assembly, CN114652920A records a method for assembling a prefilled syringe assembly with a protective cover, which specifically includes the following steps:

[0007] S1. Insert the needle sleeve unit axially into the protective cover unit;

[0008] S2. The protective cover unit with the needle sleeve unit is axially sleeved on the mounting portion;

[0009] S3. Push the piston into the syringe;

[0010] S4. Insert the push rod onto the piston.

[0011] However, the above assembly method has a drawback: during step S2, the needle may pierce the needle cover unit. This puncture will produce a large amount of rubber debris, which is unacceptable for medical applications because it compromises the sterile environment. Typically, on the production line, a camera is used to confirm whether the needle cover has been punctured, allowing prefilled syringes with punctured needle covers to be removed promptly. However, due to the obstruction of the protective cover unit, it is difficult for workers to visually confirm whether the needle cover unit is punctured, making it impossible to promptly remove prefilled syringes with punctured needle covers from the production line, thereby creating a certain degree of medical or commercial risk.

[0012] In summary, there is currently a need for a pre-filled injection needle assembly method that can easily confirm whether the needle cover is pierced by the needle during the assembly process and can also smoothly install a protective cover on the outside of the needle cover. Technical Solutions

[0013] The present invention provides a method for assembling a prefilled syringe. This method uses a sleeve to expand the protective cover from the inside out, avoiding the risk of the protective cover becoming stuck on the needle guard or needle seat during subsequent installation. This method allows the needle guard to be installed first, checked for punctures using a camera, and then the protective cover installed.

[0014] The technical solution adopted by the present invention to solve the above problem is: an assembling method of a prefilled syringe, wherein the prefilled syringe comprises:

[0015] Syringes, used to package liquids;

[0016] A needle seat, mounted at the distal end of the syringe;

[0017] a needle, mounted on the needle seat and connected to the syringe to allow the liquid to flow;

[0018] a protective cover, at least partially sleeved on the syringe and at least partially sleeved on the needle seat;

[0019] a needle guard at least partially sheathed on the needle hub to completely sheath the needle;

[0020] The proximal end of the protective cover is provided with a stop hook which contracts radially inwards and is used to lift the proximal end surface of the needle seat;

[0021] The assembly method includes the following steps:

[0022] S01. The needle sheath is attached to the needle holder, and a camera is used to confirm whether the needle sheath is pierced by the needle;

[0023] S02. The sleeve pressure head is inserted into the protective cover for radially outwardly lifting the stop hook, wherein the minimum inner diameter of the sleeve pressure head is greater than the maximum outer diameter of the needle sleeve;

[0024] S03. The protective cover of the sleeve pressure head has been inserted into the needle seat;

[0025] S04. Take out the sleeve pressure head from the protective cover.

[0026] A further preferred technical solution is that the minimum inner diameter of the sleeve pressure head is greater than the maximum outer diameter of the needle sleeve.

[0027] A further preferred technical solution is that the minimum outer diameter of the sleeve pressure head is greater than the maximum outer diameter of the needle seat.

[0028] A further preferred technical solution is that the wall thickness of the sleeve pressure head is 50-70 mm.

[0029] A further preferred technical solution is that the proximal end of the protective cover is further provided with a cantilever for lifting the distal end surface of the needle seat.

[0030] A further preferred technical solution is that: a cantilever groove is provided on the stop hook, and the cantilever is arranged on the inner side surface of the distal end of the cantilever groove.

[0031] A further preferred technical solution is that: a contraction ring for engaging with the distal end surface of the needle seat is provided at the distal end of the protective cover.

[0032] A further preferred technical solution is that: a cantilever hook for engaging with the distal end surface of the needle seat is provided at the distal end of the protective cover.

[0033] A further preferred technical solution is that the sleeve pressure head material includes one or more combinations of polypropylene, polyethylene, and polystyrene.

[0034] A further preferred technical solution is that a stop bump is further provided at the distal end of the sleeve pressure head. Beneficial effects

[0035] In summary, the present invention has the following advantages:

[0036] 1. The sleeve press head can be used to install the needle cover first and then the protective cover. This allows the needle cover to be checked in time after it is attached to the needle seat to see if it has been punctured by the needle, thereby improving the yield rate of pre-filled syringes on the production line.

[0037] 2. The wall thickness range of the sleeve is precisely defined, which not only meets the functions of supporting the cantilever and the stop hook, but also will not touch the needle sleeve during the sleeve connection process, avoiding the risk of the needle sleeve being punctured by the needle during the secondary installation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG1 is a schematic diagram of the needle sleeve being sleeved on the needle seat in step S01 .

[0039] FIG2 is a schematic diagram showing that the sleeve pressing head is aligned with the protective cover but not inserted in step S02 .

[0040] FIG3 is a schematic diagram of inserting the sleeve pressing head into the protective cover in step S02 .

[0041] FIG4 is a schematic diagram of sleeve-mounted protection cover inserted into the sleeve ram in step S03 .

[0042] FIG5 is a schematic diagram of removing the sleeve press head from the protective cover in step S04 .

[0043] FIG6 is a schematic structural diagram of the protective cover in the first embodiment.

[0044] FIG7 is a schematic diagram of the protective cover in FIG6 rotated 180 degrees.

[0045] FIG8 is a schematic structural diagram of the protective cover in the second embodiment.

[0046] FIG9 is a schematic diagram of the protective cover in FIG8 rotated 180 degrees.

[0047] In the accompanying drawings, the components represented by the respective reference numerals are as follows: syringe 1, needle seat 2, needle 3, protective cover 4, needle sleeve 5, stop hook 402, cantilever groove 403, cantilever 404, shrink ring 405, cantilever hook 406, stop protrusion 601. Modes for Carrying Out the Invention

[0048] 1. Distal end: refers to the syringe and the various components installed on the syringe in a normal manner, which is the end facing the needle.

[0049] 2. Proximal end: refers to the syringe and the various components installed on the syringe in a normal manner, which is away from the needle.

[0050] 3. Axis: refers to the line connecting the centroids of all cross sections of a component with a symmetrical cross section.

[0051] 4. Open: refers to the ability to expose the needle or needle sheath during operation.

[0052] 5. Closed: refers to the ability to cover the needle or needle cover during operation.

[0053] 6. Socketing: refers to the act of installing component one on the outer surface of component two when the inner diameter of component one is larger than the outer diameter of component two.

[0054] 7. Setting: refers to any method used to combine two parts together, such as bonding, snapping, welding, screwing, placement, etc.

[0055] 8. Lifting: refers to component one exerting force on component two, causing component two to move in a direction opposite to the position of component one.

[0056] 9. Minimum / Maximum Diameter: For components with a distinct axis, a cross-section perpendicular to the axis is taken. If the cross-section is approximately circular or polygonal, the narrowest portion of the cross-section is the minimum diameter of the component, and the widest portion of the cross-section is the maximum diameter. The minimum diameter of a given cross-section should not be greater than its maximum diameter.

[0057] The present invention will be further described in detail below with reference to the accompanying drawings.

[0058] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as such modifications are within the scope of the claims of the present invention, they are protected by patent law. Example 1

[0059] In this embodiment, a method for assembling a prefilled syringe is provided, wherein the prefilled syringe includes: a syringe barrel 1, a needle seat 2, a needle 3, a protective cover 4, and a needle sleeve 5, wherein the protective cover 4 is provided with a stop hook 402, a cantilever groove 403, a cantilever 404, and a shrink ring 405.

[0060] The minimum inner diameter of the sleeve press head 6 is greater than the maximum outer diameter of the needle sleeve 5 .

[0061] The minimum outer diameter of the sleeve press head 6 is greater than the maximum outer diameter of the needle seat 2 .

[0062] Referring to FIG1 , the needle guard is shown being sleeved onto the needle holder in step S01 , wherein the basic structure of the prefilled syringe can also be seen, including:

[0063] Syringe 1, used for packaging liquid;

[0064] The needle seat 2 is mounted at the distal end of the syringe 1;

[0065] a needle 3 mounted on the needle seat 2 and connected to the syringe 1 to allow the liquid to flow;

[0066] The needle sheath 5 is at least partially sheathed on the needle hub 2 to completely sheath the needle 3 .

[0067] Referring to Figure 1, in step S01, the needle cover 5 is placed onto the needle hub 2 to completely cover the needle 3. This process is completed using conventional production line equipment for prefilled syringes. First, on the production line, the syringe and needle cover undergo pretreatment steps such as cleaning and disinfection to ensure product hygiene and quality. The syringe is then positioned in a fixed position, typically controlled by a robotic arm or conveyor system. The needle cover is then prepared and automatically supplied to the position of the sleeve assembly, typically via a feeding system or vibrating plate. Next, the sleeve assembly process begins. Once the syringe and needle cover are ready, the sleeve assembly precisely inserts the needle cover into the needle tip of the syringe. This process may involve mechanical operations, such as rotation and pressure, to ensure a secure connection between the needle cover and the syringe.

[0068] Specifically, after the sleeve is connected, the syringe undergoes a quality inspection to ensure that the needle guard 5 has not been punctured by the needle 3. This inspection process utilizes conventional cameras. In this embodiment, one or more high-resolution industrial cameras are installed on the assembly line, typically connected to image processing software and a control system. The syringe is positioned within the camera's field of view, typically controlled by a conveyor system or robotic arm. The camera captures images of the syringe's needle tip. These images can include different angles and lighting conditions, allowing for a more comprehensive inspection of the sleeve connection. The captured images are then transmitted to image processing software for analysis. The software uses algorithms and pattern recognition techniques to detect needle guard punctures. For example, methods such as edge detection, shape matching, or color analysis can be used to identify anomalies. Based on the image processing results, the system determines whether each syringe's sleeve has passed quality inspection. If an anomaly is detected, an alarm may be triggered or the unqualified product may be removed from the assembly line. Furthermore, the system typically records the inspection results for each syringe and generates statistical data for quality control and improvement.

[0069] Referring to Figure 2, a schematic diagram is shown in which the sleeve pressure head is aligned with the protective cover but not inserted in step S02. It can be seen that the protective cover 4 is at least partially sleeved on the syringe 1 and at least partially sleeved on the needle seat 2; a sleeve pressure head 6 is also provided coaxially with the protective cover 4, and the sleeve pressure head 6 can be inserted into the protective cover 4. As can be seen in the figure, the needle seat 2 has a radially outwardly expanding ridge, which will hinder the installation process of the protective cover 4. The specific structure of the protective cover 4 is shown in Figure 6. It can be seen that the proximal end of the protective cover 4 is provided with a radially inwardly contracted stop hook 402 for lifting the proximal surface of the needle seat 2. The proximal end of the protective cover 4 is also provided with a cantilever 404 for lifting the distal surface of the needle seat 2. The way in which the protective cover 4 realizes its function can be referred to CN114642793A.

[0070] The radially outwardly flared ridges of the needle hub 2 can block the stop hooks 402 or cantilever arms 404 of the shield 4 during installation, hindering smooth installation. Furthermore, the inwardly retracted stop hooks 402 or cantilever arms 404 can contact the needle guard 5 during installation, creating a risk that the needle 3 could puncture the needle guard 5. This would render the camera inspection of the needle guard 5 in step S01 meaningless. Therefore, in this embodiment, before attaching the shield 4 to the needle hub 2, referring to FIG3 , the sleeve press 6 is first inserted into the shield 4 from the distal end, with the stop hooks 402 and cantilever arms 404 facing the distal end. This allows the sleeve press 6 to follow the stop hooks 402 and cantilever arms 404, pressing them radially outward, during insertion. Furthermore, the minimum inner diameter of the sleeve press 6 is greater than the maximum outer diameter of the needle guard 5. Therefore, even when the sleeve press 6 and the protective shield 4 are engaged with the needle guard 5, the sleeve press 6 theoretically does not come into contact with the needle guard 5. That is, the needle guard 5 that was not punctured in step S01 remains intact during the engagement process. Furthermore, the minimum outer diameter of the sleeve press 6 is greater than the maximum outer diameter of the needle hub 2. The maximum outer diameter of the needle hub 2 is the maximum outer diameter of the radially outwardly extending ridge of the needle hub 2. When the minimum outer diameter of the sleeve press 6 is greater than the maximum outer diameter of the needle hub 2, the stop hook 402 and cantilever 404 radially outwardly pressed by the sleeve press 6 can easily pass over the ridge, i.e., they will not be blocked by the needle hub 2. Referring to FIG. 4 , when the protective shield 4 is fully engaged with the needle guard 5, the stop hook 402 can completely pass over the ridge of the needle hub 2.

[0071] In addition, referring to FIG4 , when the sleeve press 6 is not long enough to directly contact the stop hook 402, although it can be seen in the figure that the sleeve press 6 does not directly push the stop hook 402 radially outward, but only pushes the cantilever 404 radially outward, since the cantilever 404 is installed in the cantilever groove 403 provided on the stop hook 402, when the sleeve press 6 pushes the cantilever 404 radially outward, it also acts on the stop hook 402 to a certain extent. When the sleeve press 6 is long enough to directly contact the stop hook 402, the sleeve press 6 can contact the stop hook 402 and the cantilever 404 at the same time, and the stop hook 402 does not need to be driven by the cantilever 404.

[0072] Referring to Figure 5, a schematic diagram illustrating the removal of the sleeve ram from the protective cover in step S04 is shown. Once the protective cover 4 is completely encased in the needle guard 5, the sleeve ram 6 can be immediately withdrawn distally. At this point, the stop hook 402 and cantilever arm 404 return to their original radially inwardly retracted positions, respectively firmly engaging the proximal and distal sides of the ridge of the needle hub 2.

[0073] In addition, referring to Figure 4, a stop protrusion 601 is also provided on the distal side of the sleeve press head 6. The function of the stop protrusion 601 is to facilitate the movement of the sleeve press head 6 and prevent the sleeve press head 6 from being fully inserted into the protective cover 4 during the insertion process and unable to be pulled out in step S04. Example 2

[0074] In this embodiment, the assembly method of the prefilled syringe is basically the same as that of the first embodiment, except that:

[0075] The protective cover 4 is provided with a cantilever hook 406 .

[0076] The wall thickness of the sleeve press head 6 is 50-70 mm.

[0077] The material of the sleeve press head 6 includes one or more combinations of polypropylene, polyethylene, and polystyrene.

[0078] In this embodiment, the cantilever hook 406 engages the ridge of the needle hub 2, preventing the protective shield 4 from fully resting on the syringe 1. Its function is similar to that of the retractable ring 405, but the cantilever hook 406 also tends to retract inward, blocking the sleeve ram 6 when it is inserted into the protective shield 4. In this embodiment, the sleeve ram 6 has a wall thickness of 50-70 mm, which provides sufficient strength while not being too thick to contact the needle guard 5 when inserted into the protective shield 4. Alternatively, the sleeve ram 6 could be made of a metal material, such as stainless steel, to achieve a similar effect. Example 3

[0079] In this embodiment, the assembly method of the prefilled syringe described in Example 1 is used, the sleeve indenter 6 is made of stainless steel, and sleeve indenters 6 with different wall thicknesses are used for testing. The test results are shown in the following table:

[0080]

[0081] Among them, it can be seen that when the wall thickness of the sleeve press head 6 is 30 thread, although it will not contact the needle sleeve 5, its strength is not enough to lift the stop hook 402 and the cantilever 404, and it will deform under the radial contraction force of the stop hook 402 and the cantilever 404; when the wall thickness of the sleeve press head 6 is 40 thread, although the strength of the sleeve press head 6 can lift the cantilever 404, the strength of its proximal end is not enough to lift the stop hook 402, and when the wall thickness of the sleeve press head 6 is between 50 and 70 thread, the strength of the sleeve press head 6 can lift the stop hook 402 and the cantilever 404 at the same time, and its inner side will not contact the needle sleeve 5; when the wall thickness of the sleeve press head 6 is 80 thread, although the strength of the sleeve press head 6 can lift the stop hook 402 and the cantilever 404 at the same time, due to its excessive wall thickness, it will contact the needle sleeve 5 during the insertion process, and there is a risk of the needle 3 piercing the needle sleeve 5.

[0082] In addition, the same or similar reference numerals are used in the drawings and description to refer to the same or similar parts or steps whenever possible. The drawings are presented in simplified form and are not drawn to exact scale. For convenience and clarity only, directional terms such as top, bottom, left, right, upward, above, above, below, below, rear, and front may be used in the drawings. These and similar directional terms should not be construed as limiting the scope of this disclosure in any way.

Claims

1. A method for assembling a prefilled syringe, wherein the prefilled syringe comprises: A syringe (1), used for packaging liquid; A needle seat (2) mounted on the distal end of the syringe (1); A needle (3) mounted on the needle seat (2) and connected to the syringe (1) to allow the liquid to flow; A protective cover (4) at least partially sleeved on the syringe (1) and at least partially sleeved on the needle seat (2); A needle sleeve (5) at least partially sleeved on the needle seat (2) to completely sleeve the needle (3); The proximal end of the protective cover (4) is provided with a stop hook (402) which contracts radially inwards and is used to lift up the proximal end surface of the needle seat (2); Characterized in that the assembly method comprises the following steps: S01. The needle sleeve (5) is sleeved on the needle seat (2); S02. Inserting the sleeve pressure head (6) into the protective cover (4) to radially outwardly lift the stop hook (402); S03. The protective cover (4) that has been inserted into the sleeve pressure head (6) is sleeved on the needle seat (2); S04. Taking out the sleeve pressure head (6) from the protective cover (4).

2. The method for assembling a prefilled syringe according to claim 1, characterized in that: The minimum inner diameter of the sleeve pressure head (6) is greater than the maximum outer diameter of the needle sleeve (5).

3. The method for assembling a prefilled syringe according to claim 1, characterized in that: The minimum outer diameter of the sleeve pressure head (6) is greater than the maximum outer diameter of the needle seat (2).

4. The method for assembling a prefilled syringe according to claim 1, characterized in that: The wall thickness of the sleeve pressure head (6) is 50-70 mm.

5. The method for assembling a prefilled syringe according to claim 1, characterized in that: The proximal end of the protective cover (4) is also provided with a cantilever (404) for lifting the distal end surface of the needle seat (2).

6. The method for assembling a prefilled syringe according to claim 5, characterized in that: The stop hook (402) is provided with a cantilever slot (403), and the cantilever (404) is arranged on the inner side surface of the distal end of the cantilever slot (403).

7. The method for assembling a prefilled syringe according to claim 1, characterized in that: A shrink ring (405) for engaging with the distal end surface of the needle seat (2) is provided at the distal end of the protective cover (4).

8. The method for assembling a prefilled syringe according to claim 1, characterized in that: A cantilever hook (406) is provided at the distal end of the protective cover (4) for engaging with the distal end surface of the needle seat (2).

9. The method for assembling a prefilled syringe according to claim 1, characterized in that: The material of the sleeve pressure head (6) includes one or more combinations of polypropylene, polyethylene, and polystyrene.

10. The method for assembling a prefilled syringe according to claim 1, characterized in that: A stop convex block (601) is also provided at the distal end of the sleeve pressure head (6).

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