Exhaust screw and barrel device for injection molding machine

Abstract

The utility model relates to a kind of exhaust screw and barrel device for injection molding machine, wherein screw has exhaust section, and the outer surface of exhaust section has first screw edge;The bottom diameter of exhaust section is 0.45~0.7 times of the diameter of screw;The pitch of first screw edge is set as L, the diameter of screw is D, and the relationship formula is satisfied: L=(1.5~2.5)D.In the utility model, the structure is optimized, and when actually applied, the exhaust effect can be improved, and the overflow from the exhaust hole of barrel is inhibited, which has good practicality and generalizability.

Description

Technical Field

[0001] This utility model relates to an exhaust screw for an injection molding machine and a barrel device having the same, belonging to the field of injection molding machine structural design. Background Technology

[0002] The barrel assembly is one of the core components of an injection molding system. Internally, it works with the screw to form a plasticizing cavity. Externally, it is equipped with segmented heating coils and thermocouples for precise temperature control. It heats and shears solid plastic granules, melting them into a homogeneous melt, which is then conveyed to the nozzle for injection. During injection molding, moisture, air, or decomposition gases are often generated. Traditional no-bake injection molding machines often use screws with venting sections to remove these gases, i.e., venting holes are opened on the barrel wall at specific locations on the screw (venting sections). However, traditional venting screw designs have significant shortcomings: the screw pitch of the venting section is usually equivalent to the screw diameter (i.e., L≈D). This design leads to excessive material filling in the venting section, resulting in high pressure within the cavity. On the one hand, excessive pressure hinders the effective escape of gases from the molten material, reducing venting efficiency and affecting the quality and performance of the final product (such as generating defects like bubbles). On the other hand, high filling and high pressure easily cause molten material to overflow from the venting holes (commonly known as "overflow"), not only wasting raw materials and contaminating the equipment but also increasing the burden of cleaning and maintenance, affecting the continuity and stability of production. Utility Model Content

[0003] In response, this utility model provides an venting screw for injection molding machines that can effectively improve venting performance and help suppress material overflow, as well as a barrel device using the screw.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] In a first aspect, this utility model provides an venting screw for an injection molding machine. The screw has a venting section, and the outer surface of the venting section has a first threaded edge. The bottom diameter of the venting section is 0.45 to 0.7 times the diameter of the screw. The pitch of the first threaded edge is set to L, and the diameter of the screw is D, satisfying the relationship: L = (1.5 to 2.5)D.

[0006] In some embodiments, the screw is further provided with a feeding section, a compression section and a plasticizing section on the rear side of the exhaust section.

[0007] In some embodiments, the outer walls of the feeding section, compression section and plasticizing section are provided with a second screw rib, and the pitch of the second screw rib is smaller than the diameter of the screw.

[0008] In some embodiments, the plasticizing section includes a strongly plasticizing section and a weakly plasticizing section, the weakly plasticizing section being disposed behind the strongly plasticizing section, both the strongly plasticizing section and the weakly plasticizing section having equal diameter structures, and the bottom diameter of the strongly plasticizing section being larger than the bottom diameter of the weakly plasticizing section.

[0009] In some embodiments, the length of the exhaust section is greater than the pitch of the first screw thread.

[0010] Secondly, this utility model also provides a material cylinder device, including a material cylinder and a screw disposed inside the material cylinder; the screw is any of the screws described above, and the material cylinder is provided with an exhaust hole at a position corresponding to the exhaust section.

[0011] In some embodiments, the number of exhaust holes is multiple, and the inner diameter of each exhaust hole is no greater than 2mm.

[0012] The positive effects of this utility model are as follows: The structure of the venting screw and barrel device for injection molding machines is optimized in this utility model. The bottom diameter of the venting section is set to be 0.45 to 0.7 times the screw diameter. By limiting the bottom diameter of the venting section, the strength of the screw is guaranteed while ensuring the venting function of the screw. Furthermore, the pitch of the first screw thread is set to L, and the diameter of the screw is set to D, satisfying the relationship: L = (1.5 to 2.5)D. By controlling the pitch of the first screw thread to a relatively large size, the filling degree of the material in the venting section can be reduced, thereby reducing the pressure at the venting section in the barrel. This is conducive to the escape of gas in the material to improve the injection molding production effect, and can also effectively suppress the overflow of material through the venting hole, avoiding excessive material overflow and waste. Attached Figure Description

[0013] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art are briefly introduced below. Similar elements or parts in the drawings are generally identified by similar reference numerals. The elements or parts in the drawings are not necessarily drawn to scale.

[0014] Figure 1 This is a cross-sectional view of the material cylinder device in this utility model;

[0015] Figure 2 for Figure 1 A magnified view of a portion of point A in the middle;

[0016] Figure 3 This is a front view of the exhaust screw in this utility model.

[0017] The reference numerals in the figure are as follows: 1. Barrel; 11. Vent hole; 12. Feed inlet; 2. Screw; 21. Vent section; 22. First screw thread; 23. Feeding section; 24. Compression section; 25. Plasticizing section; 251. Strong plasticizing section; 252. Weak plasticizing section; 26. Second screw thread. Detailed Implementation

[0018] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0019] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application shall have the ordinary meaning as understood by one of ordinary skill in the art to which this utility model pertains.

[0020] Example 1: The exhaust screw structure for the injection molding machine in this embodiment of the present invention is as follows: Figure 3 As shown, the screw 2 is provided with a feeding section 23, a compression section 24, a plasticizing section 25 and an exhaust section 21 along its axial material conveying direction (i.e., from back to front). When in use, the screw 2 is installed in the barrel 1. The barrel 1 is provided with an exhaust hole 11 at a position corresponding to the exhaust section 21. Through the exhaust hole 11, the gas generated in the molten material (such as moisture, air, decomposition gas, etc.) can be discharged from the barrel 1 to achieve the purpose of exhaust.

[0021] A first screw ridge 22 is provided on the outer surface of the exhaust section 21. During the feeding process, the first screw ridge 22 pushes the material. The bottom diameter of the exhaust section 21 is 0.45 to 0.7 times the diameter of the screw 2. The bottom diameter of the exhaust section 21 is limited to ensure the exhaust function of the screw 2 while ensuring the strength of the screw 2. The pitch of the first screw ridge 22 is further set to L, and the diameter of the screw 2 is D, satisfying the relationship: L = (1.5 to 2.5)D. For example, L = 1.5D, L = 1.8D, L = 2D, L = 2.2D, L = 2.5D, etc. can be set. In practical applications, for example, if the diameter D of the screw 2 is 28mm, the pitch L of the first screw ridge 22 can be set to 42mm to 70mm. When the diameter D is 40mm, the pitch L of the first screw ridge 22 can be set to 60mm~100mm. In traditional venting screws, the diameter D of the venting section 21 is roughly equal to the pitch L of the first screw ridge 22. In practical applications, the material filling degree of the venting section 21 is relatively high, which is not conducive to venting and the overflow phenomenon is relatively serious. In this embodiment, by controlling the pitch of the first screw ridge 22 to a relatively large size, the material filling degree of the venting section 21 can be reduced, and the pressure at the venting section 21 in the barrel 1 can be reduced. This is not only conducive to the gas in the material to escape and improve the injection molding production effect, but also can effectively suppress the overflow of material through the venting hole 11, avoiding excessive material overflow that causes waste and cleaning difficulties.

[0022] Furthermore, the outer walls of the feeding section 23, the compression section 24 and the plasticizing section 25 are provided with second screw ribs 26, and the pitch of the second screw ribs 26 is smaller than the diameter of the screw 2; this arrangement ensures that the material can be effectively pushed and compressed in the corresponding parts.

[0023] See Figure 3 As shown, the plasticizing section 25 includes a strong plasticizing section 251 and a weak plasticizing section 252. The weak plasticizing section 252 is located behind the strong plasticizing section 251. Both the strong plasticizing section 251 and the weak plasticizing section 252 are of equal diameter, and the bottom diameter of the strong plasticizing section 251 is larger than that of the weak plasticizing section 252. With this design, during the material conveying process, after being squeezed by the compression section 24, the material first enters the weak plasticizing section 252 for preliminary plasticizing, and then enters the strong plasticizing section 251 for strong pressure plasticizing. Compared with the traditional screw where the material directly enters the strong plasticizing section 251 from the compression section 24, the solution in this application can reduce the material conveying resistance and ensure the plasticizing effect of the material.

[0024] In some embodiments, the length of the exhaust section 21 is greater than the pitch of the first screw thread 22 to ensure the length of the exhaust section 21, so that there is sufficient time to release the internal gas during the material conveying process, thereby improving the exhaust effect.

[0025] Example 2: This embodiment of the invention also provides a material cylinder device for a no-drying injection molding machine, such as... Figure 1 and Figure 2 As shown, it includes a barrel 1 and a rotatable screw 2 disposed inside the barrel 1; the screw 2 adopts the screw structure in Embodiment 1; a feed inlet 12 is provided on the barrel 1 at a position corresponding to the feeding section 23, and the material is added into the barrel 1 through the feed inlet 12; an exhaust hole 11 is provided on the barrel 1 at a position corresponding to the exhaust section 21. Further, there are multiple exhaust holes 11, and the inner port diameter of each exhaust hole 11 is no greater than 2mm, such as setting the inner port diameter of the exhaust hole 11 to 0.5mm, 1mm, 1.5mm, 1.8mm, 2mm, etc.; limiting the inner port diameter of the exhaust hole 11 to a small size (≤2mm) can further suppress the overflow phenomenon of the exhaust hole 11; in practical applications, when this barrel device is installed on an injection molding machine, it is preferable to make the outer port of the exhaust hole 11 downward or obliquely downward, so as to facilitate the discharge of the material entering the exhaust hole 11 and avoid blockage.

[0026] For those skilled in the art, other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, these obvious variations or modifications derived from the essential spirit of this invention still fall within the scope of protection of this invention.

Claims

1. A venting screw for an injection molding machine, the screw (2) having a venting section (21), the outer surface of said venting section (21) having a first threaded ridge (22); characterized in that, The bottom diameter of the exhaust section (21) is 0.45 to 0.7 times the diameter of the screw (2); the pitch of the first screw edge (22) is set to L, and the diameter of the screw (2) is D, satisfying the relationship: L = (1.5 to 2.5)D.

2. The venting screw for an injection molding machine according to claim 1, characterized in that, The screw (2) is further provided with a feeding section (23), a compression section (24) and a plasticizing section (25) on the rear side of the exhaust section (21).

3. The venting screw for an injection molding machine according to claim 2, characterized in that, The outer walls of the feeding section (23), compression section (24) and plasticizing section (25) are provided with second screw ribs (26), and the pitch of the second screw ribs (26) is smaller than the diameter of the screw (2).

4. The venting screw for an injection molding machine according to claim 3, characterized in that, The plasticizing section (25) includes a strong plasticizing section (251) and a weak plasticizing section (252). The weak plasticizing section (252) is located on the rear side of the strong plasticizing section (251). Both the strong plasticizing section (251) and the weak plasticizing section (252) are of equal diameter. The bottom diameter of the strong plasticizing section (251) is larger than the bottom diameter of the weak plasticizing section (252).

5. The venting screw for an injection molding machine according to claim 1, characterized in that, The length of the exhaust section (21) is greater than the pitch of the first thread (22).

6. A feed cylinder device, comprising a feed cylinder (1) and a screw (2) disposed within the feed cylinder (1), characterized in that, The screw (2) is the screw according to any one of claims 1 to 5, and the barrel (1) is provided with an exhaust hole (11) at a position corresponding to the exhaust section (21).

7. The feed cylinder device according to claim 6, characterized in that, The number of exhaust holes (11) is multiple, and the inner diameter of each exhaust hole (11) is no greater than 2mm.

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