Small hole injection molding mold and injection molding method

Abstract

A small hole injection molding mold comprises a fixed mold plate, a movable mold plate, an ejector pin, an insert, a copper rod and a mold core. The fixed mold plate comprises an insert and an ejector pin, and the ejector pin is located in the insert; and in the mold closing process of the fixed mold plate and the movable mold plate, the tip of the ejector pin is poked into the copper rod to form the small hole of the injector medicine tube, and the small hole injection molding process of the mold is utilized. The invention can avoid the eccentricity of the needle tip, reduce the accumulative error, accurately control the size, shape and tolerance of the needle hole, prevent the edge of the small hole from being scratched to generate chippings during demolding, protect the needle tip from being easily broken, reduce the rejection rate and the production cost, and improve the production efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of molds, and more specifically, to the technical field of injection molding molds, and particularly to a micro-injection molding mold for a needleless syringe medicine tube and an injection molding method. Background Art

[0002] Needleless injection, also known as needle-free injection, needleless type injection, and jet injection, is a technology that uses a power source to generate instantaneous high pressure to pressurize the liquid medicine or freeze-dried powder medicine in the syringe, and makes the medicine penetrate the skin to reach the internal skin, subcutaneous or muscle tissue in the form of high pressure and high speed through a nozzle, so as to achieve injection without using a needle. The technology of needleless injection enables the medicine to be diffusely distributed under the skin, and is commonly used for the injection of insulin, vaccines, interferons, etc. Compared with the traditional needle injection technology using stainless steel needles, it has the advantages of fast drug absorption, uniform dispersion, high absorption rate, small trauma, reduced pain, and elimination of injection fear.

[0003] The basic structure of a needleless syringe includes a medicine tube, a power device, and an injection orifice. Among them, the inside of the medicine tube is used to load the medicine, and one end of it is connected to the power device; the power device can be powered by a spring mechanism, carbon dioxide gas, magnetism, or electricity; the other end of the medicine tube has an injection orifice, and the injection orifice is used to suck and inject the medicine. The injection orifice is a key component of the needleless syringe, and strict requirements are imposed on its shape, size, tolerance, angle, etc. For example, its diameter is generally required to be about 0.1 mm, the tolerance is generally required to be between ±0.01, and it is required that it does not shift, deform, bend, etc. during use.

[0004] There are two common methods for manufacturing a needleless syringe medicine tube. One is the traditional glass syringe processing method, in which one end of the glass tube is heated and softened and a spray hole is formed by some means. The injection orifice manufactured by this method is difficult to meet the above requirements; the other is the mold injection method, which is to pre-manufacture a fine mold and perform mold injection therein to manufacture a needleless syringe medicine tube. The method of forming an injection orifice by this injection method is also called the mold orifice forming process.

[0005] Figure 1 It is a schematic structural diagram of a mold for manufacturing a needleless syringe used in the prior art for the mold orifice forming process. Figure 2 It is Figure 1 a partial enlarged schematic diagram of. It includes an upper template 11, a lower template 12, a syringe medicine tube 13, a mold core 17, a copper rod 16, etc. The end of the mold core 17 includes a needle-like part 171 and a needle tip 172.

[0006] At the initial state of the small-hole forming process of the mold, the upper template 11 forms the cavity of the syringe 13 and the mold core 17. After the mold is started, the lower template 12 drives the mold core 17 to vertically enter the cavity of the upper template. With the movement of the mold core, the mold core gradually occupies the central position of the cavity, and the space of the syringe 13 is gradually formed at the above cavity position. With the continuous movement of the mold core, the needle-like part 171 of the mold core gradually approaches the copper rod 16. When the tip 172 completely inserts into the copper rod, the movement of the mold core stops. During the movement of the mold core, the injection molding material of the syringe tube gradually enters the syringe space, thus finally forming the small-hole syringe tube 13.

[0007] In the above-mentioned small-hole forming process of the mold, since the tip and the mold core are an integral part and the length of the whole mold core is relatively long, it is not easy to ensure the coaxiality during processing. Especially, the tip is prone to eccentricity, and the cumulative error is relatively large after being installed on the mold, resulting in the front tip being inclined when stabbing the positioning copper rod, and the small-hole size of the injected syringe product is uneven and difficult to control. During the demolding step when the mold core is withdrawn, due to the cumulative error, the mold core will have slight shaking, resulting in scratching the edge of the small hole, and there will be debris in the liquid ejected when the product is used. As a result, the rejection rate of the product is high, the production cost is high, and the production efficiency is low. At the same time, since the whole relatively long mold core is prone to deformation during the injection molding process, it is impossible for the tip to stab into the same hole every time when stabbing the positioning copper rod, which will make the small holes on the product elliptical, and the tip is prone to break. At this time, the whole mold core needs to be replaced and / or debugged again, increasing the workload and cost. Summary of the Invention

[0008] Aiming at the current situation and defects of the above-mentioned existing technologies, the purpose of the present invention is to provide a manufacturing mold and a manufacturing method for a needleless syringe tube, which can avoid the eccentricity of the tip, reduce the cumulative error, accurately control the size, shape and tolerance of the needle hole, will not scratch the edge of the small hole to generate debris during demolding, protect the tip from being easily broken, reduce the rejection rate and production cost, and improve the production efficiency.

[0009] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0010] A small-hole injection molding mold, which comprises a fixed template, a movable template, a thimble, an insert block, a copper rod and a mold core; characterized in that the fixed template contains an insert block and a thimble, and the thimble is located within the insert block; during the mold closing process of the fixed template and the movable template, the tip of the thimble stabs into the copper rod to form a small hole of the syringe tube.

[0011] Further, the movable template contains a copper rod and a mold core; the mold core includes a mold core end; the copper rod is located at the mold core end and is coaxial with the mold core end.

[0012] Further, the thimble includes a main body part and a tip; the main body part is located within the insert block and completely fits the shape of the cavity inside the insert block; the tip protrudes from the insert block.

[0013] The main body part of the ejector pin is frustum - shaped or conical. The tip of the needle is located at the center of the end face with a smaller diameter of the frustum - shaped part or at the tip of the conical part. The use of frustum - shaped or conical shapes is to ensure that the ejector pin is stable and does not shake during the mold retraction stage, reducing the error of the small holes in the syringe. The insert block contains a cavity whose shape exactly accommodates the main body part of the ejector pin.

[0014] Furthermore, the copper rod is located inside the end part of the mold core, and one end face of the copper rod coincides with the end face of the end part of the mold core.

[0015] Furthermore, the end part of the mold core contains a channel that enables the copper rod to communicate with the cooling pipe.

[0016] Furthermore, the copper rod can be replaced as needed.

[0017] The copper rod is cylindrical or frustum - shaped. The end part of the mold core contains a cavity whose shape exactly accommodates the copper rod. The copper rod is in interference fit with the end part of the mold core, thus fixing the copper rod at the end part of the mold core.

[0018] There are two cases when the tip of the ejector pin pierces into the copper rod:

[0019] In one case, the hardness of the tip of the needle is greater than the hardness of the copper rod. At this time, the copper rod has no positioning groove, and the tip of the needle directly pierces into the copper rod.

[0020] In the other case, the hardness of the tip of the needle is less than or equal to the hardness of the copper rod. At this time, the copper rod contains a positioning groove that cooperates with the tip of the ejector pin. At the end of the template forward movement stage, the tip of the needle inserts into the positioning groove of the copper rod.

[0021] The present invention also includes an injection molding method that utilizes the above - mentioned mold.

[0022] This method successively includes the following steps:

[0023] Step 1: Close the moving template and the fixed template;

[0024] Step 2: Injection molding;

[0025] Step 3: Integrally extract the mold core and the copper rod.

[0026] Furthermore, the process steps are as follows:

[0027] First, the preparation stage. Before the template starts, the insert block in the fixed template and the ejector pin are pre - assembled and installed. The copper rod in the moving template is pre - assembled and installed at the end part of the mold core.

[0028] Second, the template forward stage. The template starts, and the moving template drives the mold core and the copper rod to gradually move forward along the established track and approach the fixed template. When the copper rod is about to contact the tip of the ejector pin, the moving speed of the template slows down. Then, the copper rod slowly contacts the tip until the tip completely pierces into the copper rod.

[0029] Third, the injection molding stage. The resin material of the syringe is injected into the mold, and the cooling tube is energized or cooled by passing cooling oil to play a cooling role until the resin is completely cooled to form a small-hole syringe tube.

[0030] Fourth, the template retraction stage. The template starts, and the moving template drives the mold core to retract along the established track. The mold core drives the copper rod to separate from the tip of the ejector pin.

[0031] Finally, the small-hole syringe tube is removed from the mold, and the process is completed.

[0032] After the injection molding stage is completed, in the moving template, the syringe tube, the mold core, and the cooling tube are coaxially arranged from the outside to the inside. At this time, the tip of the ejector pin passes through the syringe tube and pierces into the copper rod. The part where the tip contacts the syringe tube forms a small hole in the syringe tube after the resin of the tube cools.

[0033] The function of the cooling tube is to cool the resin material so that the resin material solidifies into a syringe tube. This resin material is generally PC.

[0034] Compared with the prior art, the present invention has the following beneficial technical effects:

[0035] First, the present invention separates the ejector pin from the mold core, reducing the processing difficulty of the ejector pin and ensuring the absolute stability of the tip.

[0036] Second, the ejector pin is arranged in the insert block in the fixed template, and at the same time, the copper rod is arranged at the end of the mold core. The shape of the copper rod closely matches the shape of the end of the mold core, which can ensure the coaxiality of the copper rod and the mold core. It avoids the drawbacks in the prior art that the tip is on the mold core, the overall length of the mold core is too long, the tip is prone to deformation and fracture, and the injection-molded product has oval holes and unstable dimensions.

[0037] Third, during the processing, the mold core drives the copper rod to move near the tip of the ejector pin and pierces the copper rod into the tip. Under such injection molding conditions, the tip is stable and the small hole of the syringe tube is not easily eccentric.

[0038] Fourth, the copper rod is located at the end of the mold core and closely fits the end of the mold core. Before the mold moves, the operator can replace different copper rods through the channel according to needs. Description of the Drawings

[0039] Figure 1 It is a schematic structural diagram of a mold for manufacturing a needleless syringe tube used in the prior art for the small-hole forming process of a mold.

[0040] Figure 2 is Figure 1 a partial enlarged schematic view in

[0041] Figure 3 a structural schematic view of a small-hole injection molding die for manufacturing a needleless syringe medicine tube according to the present invention.

[0042] Figure 4 an enlarged schematic view of a thimble in a small-hole injection molding die for manufacturing a needleless syringe medicine tube according to the present invention.

[0043] Figure 5 is Figure 3 an enlarged schematic view of the circled part of

[0044] Figure 6 a flowchart of an injection molding method according to the present invention.

[0045] Among them, the reference numerals are represented as:

[0046] 11 upper template; 12 lower template; 13 syringe medicine tube; 16 copper rod; 17 mold core; 171 needle-like part; 172 needle tip;

[0047] 21 fixed template; 22 movable template; 23 syringe medicine tube; 24 thimble; 25 insert block; 26 copper rod; 27 mold core; 28 cooling pipe; 29 channel; 241 main body part; 242 needle tip; 271 mold core end. Detailed implementation manners

[0048] To make the purpose, technical solutions and advantages of the present invention clearer and more understandable, the following preferred embodiments are cited with reference to the accompanying drawings, and the present invention is further described in detail. It should be noted that many details listed in the specification are only for enabling the reader to have a thorough understanding of one or more aspects of the present invention, and these aspects of the present invention can be implemented even without these specific details.

[0049] The structure and working principle of the mold in the present invention are described in detail below through specific examples. To make the purpose, technical solutions and advantages of the present invention clearer and more understandable, the present invention is further described in detail below with reference to the accompanying drawings.

[0050] A small-hole injection molding die of this embodiment. As Figure 3 shown, a small-hole injection molding die includes a fixed template 21, a movable template 22, a thimble 24, an insert block 25, a copper rod 26 and a mold core 27. The fixed template 21 includes the insert block 25 and the thimble 24.

[0051] The moving template 22 contains a cavity, in which a syringe tube 23, a core 27, a cooling tube 28 and a copper rod 26 can be accommodated. The syringe tube 23, the core 27 and the cooling tube 28 are arranged coaxially from outside to inside in the cavity, that is, the core 27 is located inside the syringe tube 23, and the cooling tube 28 is located inside the core 27.

[0052] As Figure 4 shown, the ejector pin 24 includes an ejector pin main body part 241 and a tip 242. The main body part 241 is in the shape of a frustum of a cone, and the small-diameter end face of the frustum of the cone is fixedly connected to the tip 242 tightly. The main body part 241 is completely accommodated in the insert 25, and the shape of the cavity in the center of the insert 25 is completely matched with the shape of the main body part 241. The tip 242 protrudes from the insert 25. After the templates are closed later, the tip 242 is inserted into the copper rod 26 in the moving template 22.

[0053] As Figure 3 and Figure 5 shown, the core 27 includes a core end part 271, and the core end part 271 is in the shape of a frustum of a cone. The copper rod 26 is located inside the core end part 271. The copper rod 26 is a cylinder, and one end face of the copper rod 26 coincides with the small-diameter end face of the frustum of the cone of the core end part 271. The copper rod 26 is in interference fit with the core end part 271, so as to be fixedly connected to each other. After the templates are closed later, the tip 242 passes through the syringe tube 23 and pierces into the copper rod 26.

[0054] The core end part 271 includes a channel 29, and the other end face of the copper rod 26 is connected to the channel 29. The channel 29 penetrates through the core end part 271 to realize the connection between the copper rod 26 and the cooling tube 28.

[0055] When the copper rod needs to be replaced, the operator will, in the preparation stage of closing the templates, draw out the cooling tube and take out the copper rod in the reverse direction through the channel 29 from inside the core.

[0056] Specifically, the process steps are as follows:

[0057] First, the preparation stage. Before the templates are started, the insert 25 in the fixed template 21 and the ejector pin 24 are pre-assembled and installed. The copper rod 26 in the moving template 22 is pre-assembled and installed in the core end part 271.

[0058] Second, the template advancing stage. The templates are started, and the moving template 22 drives the core 27 and the copper rod 26 to gradually advance along the established track and approach the fixed template 21. When the copper rod 26 is about to contact the tip 242 of the ejector pin, the movement speed of the template slows down. Then, the copper rod 26 slowly contacts the tip 242 until the tip 242 is completely pierced into the copper rod 26.

[0059] Third, the injection molding stage. The resin material of the syringe is injected into the mold, and the cooling tube 28 is filled with cooling oil to play a cooling role until the resin is completely cooled, forming the small-hole syringe medicine tube 23.

[0060] Fourth, the template retraction stage. The template starts, and the moving template 22 drives the mold core 27 to retract along the established track; the mold core 27 drives the copper rod 26 to separate from the needle tip 242; then, the small-hole syringe medicine tube 23 is removed from the mold, and the process is completed.

[0061] Attached Figure 6 shows an injection molding method. The method sequentially includes the following steps:

[0062] Step 1: Close the moving template and the fixed template;

[0063] Step 2: Injection molding;

[0064] Step 3: Integrally extract the mold core and the copper rod.

[0065] It should be noted that in this article, the term "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article, or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such a process, method, article, or device.

[0066] The above introduces a small-hole injection molding die and an injection molding method provided by an embodiment of the present invention. In this article, specific embodiments are used to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A small-hole injection molding die, which comprises a fixed template, a movable template, ejector pins, inserts, copper bars and a mold core; characterized in that, The fixed template contains inserts and ejector pins. The ejector pins are located within the inserts. During the mold closing process of the fixed template and the moving template, the tip of the ejector pin pierces into the copper rod to form a small hole for the syringe tube.

2. The small-hole injection molding die according to claim 1, characterized in that, The moving template contains a copper rod and a mold core. The mold core includes a mold core end. The copper rod is located at the mold core end and is coaxial with the mold core end.

3. The small-hole injection molding die according to claim 1, characterized in that, The ejector pin includes a main body part and a tip. The main body part is located within the insert and fits perfectly with the shape of the inner cavity of the insert. The tip protrudes from the insert.

4. The small-hole injection molding die according to claim 2, wherein The copper rod is located inside the mold core end, and one end face of the copper rod coincides with the end face of the end of the mold core end.

5. The small-hole injection molding die according to claim 2, characterized in that, The copper rod and the mold core end are fixed by interference fit.

6. The small-hole injection molding die according to claim 2, characterized in that, The mold core end includes a channel that enables the copper rod to communicate with the cooling pipe.

7. The small-hole injection molding die according to claim 5 or 6, characterized in that The copper rod can be replaced as needed.

8. The small-hole injection molding die according to claim 3, wherein, The main body part of the ejector pin is frustum-shaped or conical.

9. An injection molding method, which uses the mold as described in claim 1, characterized in that, It successively includes the following steps: Step 1: Close the moving template and the fixed template. Step 2: Injection molding. Step 3: Withdraw the mold core and the copper rod integrally.

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