Special screw rod for PET (Polyethylene Terephthalate) bottle preform

Abstract

A special screw rod for PET bottle preforms comprises a rod body and is characterized in that a mixing section is arranged at the discharging end of the rod body, concave grooves and convex grooves are obliquely formed in the mixing section, the concave grooves and the convex grooves are alternately arranged, the inclination directions of the concave grooves and the convex grooves are the same, a plurality of sections of material passing areas are arranged in the concave grooves, and the material passing areas are communicated with the concave grooves. Wherein the material passing sectional area of the first section of material passing area is gradually reduced, the material passing sectional area of the second section of material passing area is gradually increased, the material passing areas of the concave grooves and the convex grooves are sequentially arranged subsequently, the material passing areas of the concave grooves and the convex grooves are in one-to-one correspondence and alternate, the concave grooves and the convex grooves are obliquely formed in the mixing section, and a limiting hole is formed in one end of the rod body. By adopting the concave grooves and the convex grooves which are arranged in a staggered manner, a plastic material is continuously extruded forwards when passing through the concave grooves, overflows through the mixing surface to be extruded towards the convex grooves, is continuously extruded forwards when passing through the convex grooves, overflows through the mixing surface to be extruded towards the concave grooves, and is sheared and plasticized, so that the mixing effect in the plasticizing process is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to screw rod processing technical field especially relates to a PET bottle embryo special screw rod. BACKGROUND

[0002] Polyethylene terephthalate is the most main variety in thermoplastic polyester, is called PET or PETP for short, commonly known as dacron resin, typical product is PET bottle, PET bottle has very strong applicability, is widely used in daily necessities and daily chemical packaging etc. Field.From mold processing to machine equipment has extremely strong pickiness, easy to start, difficult to do fine. PET bottle embryo is formed plastic bottle through blow molding secondary processing, including the bottle used for the packaging of cosmetics, medicine, health care, beverage, mineral water and reagent, this bottle making method is called two-step method, that is, through injection molding processing to form bottle embryo, then blow molding processing to form PET plastic bottle method. The screw plays a crucial role in injection molding processing equipment, the ordinary screw used in injection molding machine is not sufficient when plasticizing plastic, gas exists in plastic and cannot be excluded, resulting in plastic material not smooth in the conveying process, which may cause excessive compression phenomenon, increasing the scrap rate or the rate of defective products in plastic products;

[0003] The utility model discloses a kind of PET bottle embryo special screw rod, including stem body, the outer surface of the stem body is sequentially provided with connecting end, first helical section, second helical section, lead section and mixing end. In the utility model, through the wave shape structure of lead section, plastic can be more fully plasticized, reduce the phenomenon that gas exists in plastic and cannot be excluded, and the spiral rib in lead section is evenly milled with several side grooves, ensure that plastic material flows smoothly, without excessive compression phenomenon, feeding section and discharge section increase depth in same proportion, ensure feeding and discharging speed, the change of length-diameter ratio further improves screw plasticizing efficiency, reduces scrap rate or the rate of defective products, reduces economic loss;

[0004] But the barrier ring of mixing end of the existing screw rod is not good in mixing effect in plasticizing process in use, to solve the above problems, a kind of PET bottle embryo special screw rod is presented. Utility model content

[0005] In view of the above technical problems, the utility model provides a PET bottle embryo special screw rod, including the stem, the stem's discharge end is provided with the mixing section, there is the recessed groove and the convex groove of inclined arrangement on the mixing section, the recessed groove and the convex groove are alternately arranged, and the inclination direction of two is same, there are a plurality of sections of the material passing area in the recessed groove, wherein the first section of the material passing area gradually reduces the material passing cross section area, the second section of the material passing area gradually increases, subsequent in turn, there are a plurality of sections of the material passing area in the convex groove, wherein the first section of the material passing area gradually increases the material passing cross section area, the second section of the material passing area gradually reduces, subsequent in turn, wherein the material passing area of recessed groove and convex groove correspond one by one and alternately, wherein, in the recessed groove first section of the material passing area, plastic material gradually changes from mixing end face deep to mixing middle shallow, in the recessed groove second section of the material passing area, from middle shallow to another end face deep gradually changes, in the convex groove first section of the material passing area, plastic material gradually changes from mixing end face shallow to mixing middle deep, in the convex groove second section of the material passing area, from middle deep to another end face shallow gradually changes, in the melting state plastic enters the mixing section, and plastic material will constantly extrude forward after passing the recessed groove, overflow mixes the surface to the extrusion of convex groove, from the convex groove will constantly extrude forward, overflow mixes the surface to the extrusion of recessed groove, repeat the above process, and plastic is sheared plasticization, reaches the purpose of high plasticization, and a plurality of groups of inclined groove rings follow the recessed groove and the convex groove, prevent slow discharge, produce multiple shearing plastic, help to improve the heat generated by plastic in screw conveying, can reduce the change of temperature, improve the occurrence of bubble, yellowing, silver wire and other phenomena in plastic products;

[0006] Further, the feed inlet and the discharge outlet of the recessed groove and the convex groove are provided with chamfers, which are used to reduce the blockage at the feed inlet and the discharge outlet, so that the plastic material can enter the recessed groove and the convex groove more smoothly, flow inward along the inclined surface of the chamfer, reduce the friction caused by the right angle, and ensure that the plastic material can enter continuously and smoothly.

[0007] Further, the mixing section is further provided with a plurality of inclined groove rings, and the inclined groove rings are located at the discharge end of the mixing section.

[0008] Further, the stem is further provided with a connecting section, a feeding section, a compression section and a wave section, the wave section is located at the right side of the mixing section, the wave section is provided with screw ribs, the bottom diameter of the screw rib is divided into two parts within one lead, the raised high point corresponds to the other part of the lowest point, and the screw ribs are staggered and arranged to form a wave-shaped bottom diameter change, and the circumferential outer side of the screw rib of the wave section is uniformly provided with a plurality of side grooves.

[0009] Further, the compression section is located at the right side of the wave section, the screw flight of the compression section is all inverted blunt and the bottom diameter gradually changes, the compression section transports the plastic material to the wave section, the inverted blunt screw flight reduces the adhesion of the molten plastic material;

[0010] Further, the feeding section is located at the right side of the compression section, the screw flight of the feeding section is equal in depth and gradually changes in outer diameter, the feeding section transports the plastic material to the compression section, the plastic material in the mixed state of solid and molten state is transported on the feeding section, and the gradually changed outer diameter improves the transportation efficiency of the mixed state;

[0011] Further, the connecting section is located at the right side of the feeding section, the outer side of the connecting section is provided with two groups of opposite connecting grooves, and the inner side of one end of the rod body is provided with a limiting hole; the screw rod is integrally installed into the injection molding machine through the limiting hole, the connecting end and the two groups of opposite connecting grooves, and rotation of the screw rod is realized.

[0012] The PET bottle embryo special screw rod has the advantages that:

[0013] The concave groove and the convex groove are staggered, the plastic material continuously extrudes forward when passing through the concave groove, overflows the mixing surface to the convex groove, continuously extrudes forward from the convex groove, overflows the mixing surface to the concave groove, shears and plasticizes the plastic, and the mixing effect in the plasticizing process is improved.

[0014] The volume of the bottom diameter is changed, the eccentric height difference of the high point and the low point is reasonably designed, the influence on the compression ratio is reduced, the volume of the plastic is utilized, the lead of the screw flight section of the screw rod is changed, the extrusion of the screw flight on the plastic is reduced, the transportation and plasticization of the plastic are promoted, the local shearing is not caused, the plastic product is not caused, the plasticization compression ratio of the plastic is ensured, the excessive plasticization of the plastic caused by the extrusion is reduced, and the design performance of the screw rod plays a key role. DRAWINGS

[0015] Figure 1 It is a whole structure schematic view of the PET bottle embryo special screw rod.

[0016] Figure 2 It is an enlarged structure schematic view of I of the PET bottle embryo special screw rod.

[0017] Figure 3 It is a sectional view of H-H and G-G of the PET bottle embryo special screw rod.

[0018] Figure 4 It is a sectional view of D-D of the PET bottle embryo special screw rod.

[0019] Figure 5 It is a sectional view of K-K of the PET bottle embryo special screw rod.

[0020] Figure 6 is a sectional view of L-L of the special screw for PET bottle blank of the utility model;

[0021] Figure 7 is a sectional view of C-C of the special screw for PET bottle blank of the utility model;

[0022] Figure 8 is a schematic view of concave groove and convex groove of embodiment 2 of the special screw for PET bottle blank of the utility model;

[0023] Figure 9 is a sectional view of the special screw for PET bottle blank of the utility model Figure 8 ;

[0024] Figure 10 is a material advancing schematic view of the special screw for PET bottle blank of the utility model Figure 8 ;

[0025] As shown in the figure: 1, shaft; 2, connecting section; 3, feeding section; 4, compression section; 5, wave section; 6, mixing section; 7, connecting groove; 8, side groove; 9, inclined groove ring; 10, concave groove; 11, convex groove; 12, limiting hole. DETAILED DESCRIPTION

[0026] The technical solutions of the utility model will be described clearly and completely below in combination with the drawings, obviously, the described embodiments are a part of embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the person skilled in the art without making creative labor belong to the protection scope of the utility model.

[0027] In the description of the utility model, it needs to be explained that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicated orientation or position relationship are based on the orientation or position relationship shown in the drawings, only for the convenience of describing the utility model and simplifying the description, and not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, cannot be understood as the limitation of the utility model. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0028] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances. Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0029] Example 1

[0030] like Figures 1-7 As shown, this utility model provides a screw for PET preforms, including a shaft 1. The discharge end of the shaft 1 has a mixing section 6. The mixing section 6 has inclined concave grooves 10 and convex grooves 11, which are alternately arranged and inclined in the same direction. The concave groove has several material passing areas, with the first material passing area gradually decreasing in cross-sectional area, the second material passing area gradually increasing in cross-sectional area, and so on. The convex groove 11 also has several material passing areas, with the first material passing area gradually increasing in cross-sectional area, the second material passing area gradually decreasing in cross-sectional area, and so on. The material passing areas of the concave groove 10 and convex groove 11 correspond one-to-one and alternate with each other. In the first material passing area of ​​the concave groove 10, the plastic material gradually changes from deep at the mixing end to shallow in the middle of the mixing process. In the second section of the material conveying zone 10, the material gradually changes from light in the middle to dark at the other end. In the first section of the material conveying zone 11 of the convex groove, the plastic material gradually changes from light at the mixing end to dark in the middle. In the second section of the material conveying zone 11 of the convex groove, the material gradually changes from dark in the middle to light at the other end. When the molten plastic enters the mixing section 6, the plastic material will be continuously squeezed forward through the concave groove 10, overflowing over the mixing surface and being squeezed into the convex groove 11. It will be continuously squeezed forward from the convex groove 11, overflowing over the mixing surface and being squeezed into the concave groove 10. The above process is repeated to shear and plasticize the plastic to achieve the purpose of high plasticization. Several sets of inclined groove rings 9 are closely connected to the concave groove 10 and the convex groove 11 to prevent slow discharge and multiple shearing of plastic. This helps to increase the heat generated by the plastic during screw conveying, which can reduce temperature changes and improve the occurrence of phenomena such as bubbles, yellowing, and silver streaks in plastic products.

[0031] Furthermore, the inlet and outlet of both the concave groove 10 and the convex groove 11 are chamfered to reduce blockage at the inlet and outlet, allowing the plastic material to enter the concave groove 10 and the convex groove 11 more smoothly and flow inward along the bevel of the chamfer, reducing the friction caused by the right angle and ensuring that the plastic material can enter continuously and smoothly.

[0032] Further, the mixing section 6 is also provided with several chute rings 9 located at the discharge end of the mixing section 6;

[0033] Further, the rod body 1 is also provided with a connecting section 2, a feeding section 3, a compression section 4, and a wave section 5 located at the right side of the mixing section 6. The wave section 5 has screw threads, the bottom diameter of which is divided into two parts within one lead, and the convex high points correspond to the lowest points of the other part. The wave section 5 is arranged in a staggered manner to form a wave-shaped bottom diameter change. The wave section 5 is uniformly provided with several side grooves 8 on the outer side of the circumference. The wave structure of the bottom diameter continuously shears and transports the plastic. The wave section 5 is provided with several side grooves 8 to increase the flow direction of the plastic and generate more shear heat. The glass state plastic is repeatedly sheared at this position to absorb a large amount of heat and further plasticize to reach a nearly fully plasticized state.

[0034] Further, the compression section 4 is located at the right side of the wave section 5. The screw threads of the compression section 4 are all inverted and blunt, and the bottom diameter gradually changes. The compression section 4 transports the plastic to the wave section 5. The inverted and blunt screw threads reduce the adhesion of the molten plastic.

[0035] Further, the feeding section 3 is located at the right side of the compression section 4. The screw threads of the feeding section 3 have an equal depth and a gradually changing outer diameter. The feeding section 3 transports the plastic to the compression section 4. The plastic in the mixed state of solid and molten state is transported in the feeding section 3. The gradually changing outer diameter improves the transportation efficiency of the mixed state.

[0036] Further, the connecting section 2 is located at the right side of the feeding section 3. The outer side of the connecting section 2 is provided with two groups of opposite connecting grooves 7. One end of the rod body 1 is internally provided with a limiting hole 12. The screw rod is integrally installed in the injection molding machine through the limiting hole 12, the connecting end, and the two groups of opposite connecting grooves 7 to realize the rotation of the screw rod.

[0037] Working principle:

[0038] In use, the device is installed inside the injection molding machine through the limiting hole 12, the connecting end, and two sets of connecting grooves 7. The injection molding machine drives the connecting section 2, feeding section 3, compression section 4, corrugated section 5, and mixing section 6 on the rod body 1 to rotate. Among them, the feeding section 3 and compression section 4 convey the plasticized plastic. The bottom diameter depth of the corrugated section 5 is processed in an alternating manner, which repeatedly stirs, shears, and extrudes the glassy plastic, fully expelling the gas in the plastic to the outside. Due to the large length-to-diameter ratio, the gas generated in the plastic is fully expelled to the outside, ensuring the uniformity of plasticization. Several side grooves 8 are evenly milled around the circumference of the corrugated section 5 to ensure that the plastic material is within the guide. The flow is smoother in the mixing section, reducing excessive compression. Then, the molten plastic enters the mixing section 6. The staggered concave grooves 10 and convex grooves 11 cause the plastic material to be continuously squeezed forward as it passes through the concave grooves 10. It overflows over the mixing surface and is squeezed into the convex grooves 11. It is continuously squeezed forward from the convex grooves 11 and overflows over the mixing surface and is squeezed into the concave grooves 10, which shears and plasticizes the plastic, improving the mixing effect during the plasticizing process. The inclined groove ring 9 is immediately connected to the concave grooves 10 and convex grooves 11 to prevent slow discharge and multiple shearing of the plastic. It helps to increase the heat generated by the plastic during screw conveying, which can reduce temperature changes and improve the occurrence of phenomena such as bubbles, yellowing, and silver streaks in plastic products.

[0039] Example 2

[0040] like Figures 8-10 As shown, when there are multiple sets of material passing zones in the concave groove 10 and convex groove 11 of the mixing section 6, the molten plastic enters the mixing section 6. The plastic material will be continuously squeezed forward through the first material passing zone of the concave groove 10, overflowing through the mixing surface and being squeezed into the first material passing zone of the convex groove 11. Then, it will continue to be squeezed forward from the second material passing zone of the convex groove 11, overflowing through the mixing surface and being squeezed into the second material passing zone of the concave groove 10. Then, it will be continuously squeezed forward again through the third material passing zone of the concave groove 10, overflowing through the mixing surface and being squeezed into the third material passing zone of the convex groove 11. Finally, it will continue to be squeezed forward from the fourth material passing zone of the convex groove 11, overflowing through the mixing surface and being squeezed into the fourth material passing zone of the concave groove 10.

[0041] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. The various components mentioned in this utility model are common technologies in the existing field. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A special screw for PET preforms comprising a shaft (1), characterized in that, The discharge end of the rod body (1) is provided with a mixing section (6), the mixing section (6) is provided with an inclined concave groove (10) and a convex groove (11), the concave groove (10) and the convex groove (11) are alternately arranged, and the inclined directions of the two are the same, the concave groove (10) has a plurality of sections of material passing area, wherein the first section of material passing area gradually reduces the material passing cross-sectional area, the second section of material passing area gradually increases the material passing cross-sectional area, and the subsequent is arranged in turn, the convex groove (11) has a plurality of sections of material passing area, wherein the first section of material passing area gradually increases the material passing cross-sectional area, the second section of material passing area gradually reduces the material passing cross-sectional area, and the subsequent is arranged in turn, wherein the material passing area of the concave groove (10) and the convex groove (11) correspond to each other and are alternated.

2. A screw dedicated to a PET preform according to claim 1, characterized in that, The feeding port and the discharge port of the whole concave groove (10) and the convex groove (11) are provided with chamfers, which are used for reducing the blockage of the feeding port and the discharge port.

3. A PET preform dedicated screw as claimed in claim 2, wherein, The rod body (1) is further provided with a connecting section (2), a feeding section (3), a compression section (4) and a wave section (5), the wave section (5) is located on the right side of the mixing section (6), the wave section (5) has screw ribs, the bottom diameter of the screw rib is divided into two parts within one lead, the raised high point corresponds to the lowest point of the other part, and the screw ribs are arranged in staggered arrangement, forming the bottom diameter change in the form of waves, and the circumferential outer side of the screw rib of the wave section (5) is uniformly provided with a plurality of side grooves (8).

4. A PET preform dedicated screw as claimed in claim 3, wherein, The compression section (4) is located on the right side of the wave section (5), the screw rib of the compression section (4) is all blunt and the bottom diameter gradually changes.

5. A PET preform dedicated screw as claimed in claim 4, wherein, The feeding section (3) is located on the right side of the compression section (4), the screw rib of the feeding section (3) has equal depth and gradually changes in outer diameter.

6. A PET preform dedicated screw as claimed in claim 5, wherein, The connecting section (2) is located on the right side of the feeding section (3), and the outer side of the connecting section (2) is provided with two groups of opposite connecting grooves (7).

7. A PET preform dedicated screw as claimed in claim 6, wherein, The mixing section (6) is further provided with a plurality of chute rings (9), and the chute rings (9) are located at the discharge end of the mixing section (6).

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