阅读说明：本技术 一种防开裂的多重渐分式树脂注射吹塑工艺 (Anti-cracking multiple gradual separation type resin injection blow molding process ) 是由 王凯 于 2020-12-07 设计创作，主要内容包括：本发明公开了一种防开裂的多重渐分式树脂注射吹塑工艺,属于树脂成型工艺领域,一种防开裂的多重渐分式树脂注射吹塑工艺,本发明通过在中空芯模上设置双头丝束,同时在中空芯模外端紧密贴合一层发胀膜,在型坯注射成型过程中,通过发胀膜和双头丝束与型坯之间的大面积深入接触,可以大大提高型坯在自动下垂时受到的摩擦力和支撑阻力,减轻型坯自重下垂情况,提高型坯壁厚的均匀度,使型坯在发胀时不易发生龟裂情况,并且,在型坯吹塑发胀过程中,通过发胀膜和双头丝束的向外扩张,将气流压力均匀全面作用于型坯上,大大减少了因气流冲击造成型坯局部发生龟裂的情况,进一步保证了成品的质量。(The invention discloses an anti-cracking multiple gradual separation type resin injection blow molding process, belonging to the field of resin forming process, wherein a double-head filament bundle is arranged on a hollow core mold, a layer of expansion film is tightly adhered to the outer end of the hollow core mold, and in the parison injection molding process, through the large-area deep contact between the expansion film and the double-head filament bundle and a parison, the friction force and the supporting resistance of the parison during automatic sag can be greatly improved, the self-weight sag condition of the parison is relieved, the uniformity of the wall thickness of the parison is improved, the parison is not easy to crack during expansion, in the parison blow molding and expansion process, the outward expansion of the expansion film and the double-head filament bundle uniformly and comprehensively acts the air pressure on the parison, and the local crack condition of the parison caused by air flow impact is greatly reduced, further ensuring the quality of the finished product.)

1. A multiple gradual separation type resin injection blow molding process for preventing cracking is characterized in that: the method comprises the following steps:

s1, film covering: sleeving the expansion film (2) on the outer side of the hollow microporous male die from bottom to top, and preliminarily fixing the upper end opening of the expansion film (2) at the outer end of the hollow microporous male die through an adhesive;

s2, depressurizing and compacting: putting the hollow microporous male die into a split injection die, then closing and fixing the die, and pumping out air in the hollow microporous male die to ensure that the expansion film (2) is tightly attached to the outer surface of the hollow microporous male die, wherein double-end tows on the hollow microporous male die penetrate through the expansion film (2) to generate film holes;

s3, injection: injecting a molten resin into an injection mold to form a parison;

s4, converting the die: taking the parison and the hollow microporous male mold out of the injection mold and placing the parison and the hollow microporous male mold into a split blow mold, and then closing and fixing the mold;

s5, blow molding and expanding: air is sent into the hollow microporous male die, the air is dispersed outwards through micropores on the hollow microporous male die, and the double-end filament bundles, the expanded membrane (2) and the parison are expanded outwards together;

s6, multiple separation: in the expansion process, the double-end filament bundle, the expansion film (2) and the parison are separated from each other in sequence, and finally the parison is attached to the cavity wall of the blow molding die except the bottle neck;

and S7, releasing air in the hollow micropore convex mold after pressure maintaining, cooling and shaping, and opening the blow molding mold to take out the plastic part.

2. The multiple progressive resin injection blow molding process of claim 1, wherein: the S6 specifically includes the following steps:

s6.1, primary separation: when the double-end tows move to the limit point, the double-end tows are separated from the expansion film (2), film holes in the expansion film (2) are exposed, and the expansion film (2) and the parison continue to expand outwards;

s6.2, double separation: when the expansion film (2) is expanded to the maximum degree, gas flows to the parison through the film holes on the expansion film (2), the expansion film (2) is separated from the parison, and the parison continues to expand outwards until the parison is attached to the cavity wall of the blow mold.

3. The multiple progressive resin injection blow molding process of claim 1, wherein: the hollow microporous male die comprises a hollow core die (1), wherein a plurality of line through holes (101) which are uniformly distributed are formed in the hollow core die (1), the double-end tows and the line through holes (101) are identical in number and correspond to each other one by one, and the double-end tows penetrate through the inner parts of the line through holes (101) and extend to the two sides of the hollow core die (1) respectively.

4. The process of claim 3, wherein the resin composition comprises: the double-end tow comprises a blocking convex body (31) and an actuating positioning body (34), wherein the blocking convex body (31) is located on the outer side of a hollow core die (1), the actuating positioning body (34) is located on the inner side of the hollow core die (1), a plurality of inelastic connecting wires (33) are fixedly connected between the blocking convex body (31) and the actuating positioning body (34), and the inelastic connecting wires (33) are slidably connected with the inner side of a wired through hole (101).

5. The process of claim 4, wherein the resin composition comprises: the interception convex body (31) is in a hollow hemispherical shape, the inelastic connecting wire (33) is fixedly connected with the inner surface of the interception convex body (31), and the outer surface of the interception convex body (31) is fixedly connected with a plurality of uniformly distributed puncture needles (32).

6. The process of claim 4, wherein the resin composition comprises: the actuating positioning body (34) is a hollow sphere, and the diameter of the outer ring of the actuating positioning body (34) and the radius of the outer ring of the interception convex body (31) are both larger than the aperture diameter of the linear through hole (101).

7. The multiple progressive resin injection blow molding process of claim 5, wherein: the sum of the gravity of the intercepting convex body (31) and the gravity of the puncture needle (32) is less than the gravity of the actuating positioning body (34).

8. The multiple progressive resin injection blow molding process of claim 1, wherein: the inner ring diameter of the expansion film (2) in a saturated expansion state is larger than the length of the double-end tows.

9. The multiple progressive resin injection blow molding process of claim 1, wherein: the split injection mold is closed outside the swelling film (2) in S2.

10. The multiple progressive resin injection blow molding process of claim 1, wherein: the expansion film (2) and the double-end tows are both made of high-temperature resistant materials.

Technical Field

The invention relates to the field of resin molding processes, in particular to an anti-cracking multi-gradual-split resin injection blow molding process.

Background

The resin generally refers to an organic polymer which has a softening or melting range after being heated, tends to flow by an external force when softened, and is solid, semi-solid, or liquid at room temperature. By broad definition, any polymeric compound that can be used as a raw material for processing plastic articles is referred to as a resin.

The resin can be used for producing film products, hollow containers with various sizes for daily use and industry, pipes, calendering belts and binding belts for packaging, ropes, fishing nets, fibers for weaving, wires and cables and the like by adopting molding methods such as injection molding, blow molding, extrusion molding, rotational molding and the like. The blow molding mainly comprises extrusion blow molding and injection blow molding, wherein in the injection blow molding process, firstly, an injection machine injects molten resin into an injection mold to form a parison, and the parison is formed on a hollow male mold with micropores on the peripheral wall; then moving the blank into a blow molding die while the blank is hot, closing the die, introducing compressed air into a pipeline of the core rod, and blowing and sticking the parison to the cavity wall of the die; and finally, releasing compressed air after pressure maintaining, cooling and shaping, opening the mold and taking out the plastic part.

However, in the injection blow molding process, the parison on the male mold tends to sag due to its own weight during the process of transferring the parison and the hollow male mold to the blow mold, and the wall thickness of the parison in the longitudinal direction tends to be uneven, thereby easily causing a crack phenomenon in the blown parison.

Disclosure of Invention

1. Technical problem to be solved

Aiming at the problems in the prior art, the invention aims to provide an anti-cracking multiple gradual-separation type resin injection blow molding process, which comprises the steps of arranging double-head tows on a hollow core mold, simultaneously tightly attaching a layer of expansion film at the outer end of the hollow core mold, in the process of parison injection molding, through the large-area deep contact between the expansion film and the double-end filament bundle and the parison, can greatly improve the friction force and the supporting resistance of the parison during the automatic sagging, reduce the sagging situation of the parison due to the dead weight, the uniformity of the wall thickness of the parison is improved, the parison is not easy to crack when expanding, and, in the blowing and expanding process of the parison, the air flow pressure is uniformly and comprehensively acted on the parison through outward expansion of the expanding film and the double-end filament bundles, so that the condition that the parison is cracked locally due to air flow impact is greatly reduced, and the quality of a finished product is further ensured.

2. Technical scheme

In order to solve the above problems, the present invention adopts the following technical solutions.

An anti-cracking multiple progressive resin injection blow molding process, comprising the steps of:

s1, film covering: sleeving the expansion film on the outer side of the hollow microporous male die from bottom to top, and preliminarily fixing the upper end opening of the expansion film at the outer end of the hollow microporous male die through an adhesive;

s2, depressurizing and compacting: placing the hollow microporous male die into a split injection die, then closing and fixing the die, and pumping out air in the hollow microporous male die to enable the expansion film to be tightly attached to the outer surface of the hollow microporous male die, wherein double-end tows on the hollow microporous male die penetrate through the expansion film to enable the expansion film to generate film holes;

s3, injection: injecting a molten resin into an injection mold to form a parison;

s4, converting the die: taking the parison and the hollow microporous male mold out of the injection mold and placing the parison and the hollow microporous male mold into a split blow mold, and then closing and fixing the mold;

s5, blow molding and expanding: air is sent into the hollow microporous male die, the air is dispersed outwards through micropores on the hollow microporous male die, and the double-end filament bundles, the expanded membrane and the parison are expanded outwards together;

s6, multiple separation: in the expansion process, the double-end filament bundle, the expansion film and the parison are separated from each other in sequence, and finally the parison is attached to the cavity wall of the blow molding die except the bottle neck;

and S7, releasing air in the hollow micropore convex mold after pressure maintaining, cooling and shaping, and opening the blow molding mold to take out the plastic part.

The double-end filament bundles are arranged on the hollow core mould, and the outer end of the hollow core mould is tightly attached with the expansion film, so that the friction force and the supporting resistance of the parison during automatic sagging can be greatly improved through large-area deep contact between the expansion film and the parison in the parison injection molding process, the self-weight sagging condition of the parison is reduced, the uniformity of the wall thickness of the parison is improved, the parison is not easy to crack during expansion, and the airflow pressure is uniformly and comprehensively acted on the parison through outward expansion of the expansion film and the double-end filament bundles in the parison blowing expansion process, so that the local cracking condition of the parison caused by airflow impact is greatly reduced, and the quality of a finished product is further ensured.

Further, the S6 specifically includes the following steps:

s6.1, primary separation: when the double-end filament bundle moves to the limit point, the double-end filament bundle is separated from the expansion film, the film hole on the expansion film is exposed, and the expansion film and the parison continue to expand outwards;

s6.2, double separation: when the expansion film is expanded to the maximum degree, gas flows to the parison through the film holes on the expansion film, the expansion film is separated from the parison, and the parison continues to expand outwards until the parison is attached to the cavity wall of the blow mold.

Before the primary separation process, the double-end filament bundle closes the membrane hole on the expansion membrane, the double-end filament bundle, the expansion membrane and the parison expand outwards together under the action of air pressure, the expansion of the expansion membrane uniformly acts on the parison, so that the parison uniformly expands.

Furthermore, the hollow microporous male die comprises a hollow core die, a plurality of uniformly distributed thread through holes are formed in the hollow core die, the double-headed tows and the thread through holes are identical in quantity and correspond to each other one by one, the double-headed tows penetrate through the inside of the thread through holes and respectively extend to two sides of the hollow core die, and in the process that the expansion film and the parison are expanded outwards, the expansion film and the parison drive the double-headed tows to move, so that the double-headed tows move outwards along the thread through holes.

Furthermore, the double-end tow comprises a blocking convex body and an actuation positioning body, the blocking convex body is positioned on the outer side of the hollow core mould, the actuation positioning body is positioned on the inner side of the hollow core mould, a plurality of inelastic connecting wires are fixedly connected between the blocking convex body and the actuation positioning body, and the inelastic connecting wires are slidably connected with the inner side of the wired through hole.

Furthermore, the interception convex body is in a hollow hemispherical shape, the inelastic connecting wire is fixedly connected with the inner surface of the interception convex body, the outer surface of the interception convex body is fixedly connected with a plurality of uniformly distributed pricking pins, when the expansion film is sleeved outside the hollow core mold, the interception convex body is positioned between the hollow core mold and the expansion film, in the process of extracting the gas in the hollow core mold, the gas in the hollow core mold moves towards the upper port, the positioning body is triggered to move upwards under the action of air flow, so that the interception convex body is driven to move by the inelastic connecting wire to be more closely attached to the outer wall of the hollow core mold, meanwhile, the expansion film is gradually attached to the outer wall of the hollow core mold under the action of air pressure, when the expansion film is in mutual contact with the interception convex body, the pricking pins can form film holes on the expansion film, and the pricking pins penetrate through the film holes to extend to the outer side of the expansion film, the expansion film is closely attached to the block convex body, therefore, when molten resin is injected, the molten resin is filled between the expansion film and an injection mold, the puncture needle penetrates into the molten resin, so that in the process of moving the parison and the hollow core mold, on one hand, the contact surface between the parison and the expansion film can be increased through the block convex body, namely, the friction force applied when the parison sags is increased, on the other hand, the hemispherical surface of the block convex body can provide support resistance for the parison to sag, and the parison and the double-end filament bundles are closely connected through close contact between the puncture needle and the interior of the parison, so that the connection resistance is further provided for the parison to sag.

Further, the priming positioning body adopts the hollow sphere, the outer lane diameter of the priming positioning body and the outer lane radius of the interception convex surface body are all greater than the orifice bore of the line through hole, so that the interception convex surface body and the priming positioning body can not pass through the line through hole, stable two-way movement of the double-end filament bundle in the line through hole is ensured, when the priming positioning body moves to be attached to the inner wall of the hollow core mold, the double-end filament bundle stops moving outwards, when the expansion film continues to expand outwards, the pricker moves back to the inner side of the expansion film through the film hole on the expansion film, and therefore separation of the double-end filament bundle and the expansion film is realized.

Furthermore, the sum of the gravity of the intercepting convex body and the pricking pin is smaller than the gravity of the actuating positioning body, so that in the initial state, the actuating positioning body is in a drooping state under the action of the gravity of the actuating positioning body, and the intercepting convex body is driven to be in a state of being attached to the outer wall of the hollow core mold, so that when the expansion film is sleeved, the hollow core mold, the expansion film and the intercepting convex body can be tightly attached to each other quickly and accurately through gas extraction.

Further, the inner circle diameter of the expansion film in the saturation expansion state is larger than the length of the double-end filament bundles, when the expansion film does not reach the saturation expansion, the positioning body is triggered to move to the hole of the line through hole, the expansion film and the double-end filament bundles start to be separated, the film hole in the expansion film is exposed, and the gas in the later period can flow to the parison through the film hole, so that the parison expands until being attached to the cavity wall.

Further, the split injection mold in S2 is closed outside the swelling film, that is: when the injection mold is closed, the upper end of the expansion film and the hollow core mold can be clamped tightly by the mold, so that the upper end of the expansion film and the hollow core mold are not easy to separate and generate air leakage in the expansion process of the expansion film, and the expansion film can be ensured to be expanded normally.

Furthermore, the expansion film and the double-end tows are both made of high-temperature resistant materials.

3. Advantageous effects

Compared with the prior art, the invention has the advantages that:

(1) this scheme is through setting up the double-end silk bundle on the cavity mandrel, the membrane that expands is sent out in the one deck of closely laminating in cavity mandrel outer end simultaneously, in parison injection moulding process, through sending out the membrane that expands and the deep contact of large tracts of land between double-end silk bundle and the parison, can improve frictional force and the supporting resistance that the parison received when automatic flagging greatly, alleviate the flagging condition of parison dead weight, improve the degree of consistency of parison wall thickness, make the parison difficult emergence the condition of splitting when sending out the expansion, and, in parison blowing send out the in-process that expands, through sending out the outside expansion of membrane and double-end silk bundle, evenly act on the parison comprehensively with air pressure, the condition that causes the local emergence of splitting of parison because of the air current impact has significantly reduced, finished product quality has further.

(2) Before the primary separation process, the double-end filament bundle closes the membrane hole on the expansion membrane, the double-end filament bundle, the expansion membrane and the parison expand outwards together under the action of air pressure, the expansion of the expansion membrane uniformly acts on the parison, so that the parison uniformly expands.

(3) The hollow microporous male die comprises a hollow core die, wherein a plurality of uniformly distributed thread through holes are formed in the hollow core die, a plurality of double-end tows and the thread through holes are identical in number and correspond to each other one by one, the double-end tows penetrate through the thread through holes and respectively extend to two sides of the hollow core die, and in the process that the expansion film and the parison are expanded outwards, the expansion film and the parison drive the double-end tows to move, so that the double-end tows move outwards along the thread through holes.

(4) When the expansion film is sleeved outside the hollow core mold, the interception convex body is positioned between the hollow core mold and the expansion film, in the process of extracting the gas in the hollow core mold, the gas in the hollow core mold moves towards the upper port, under the action of the gas flow, the positioning body is driven to move upwards, so that the interception convex body is driven to move through the inelastic connecting wire, so that the interception convex body is more closely attached to the outer wall of the hollow core mold, meanwhile, under the action of the gas pressure, the expansion film is gradually attached to the outer wall of the hollow core mold, when the expansion film is in close contact with the interception convex body, the expansion film is punctured to form a film hole, the puncture needle penetrates through the film hole to extend to the outer side of the expansion film, the expansion film is closely attached to the interception convex body of the puncture needle, therefore, when the molten resin is injected, the molten resin is filled between the expansion film and the injection mold and extends into the molten resin, so that in the process of moving the mold blank and the hollow, on one hand, the contact surface between the parison and the expansion film can be increased through the block convex body, namely, the friction force applied when the parison sags is increased, on the other hand, the hemispherical surface of the block convex body can provide supporting resistance for the parison sag, and the puncture needle is closely contacted with the inside of the parison, so that the parison and the double-end filament bundles are tightly connected, and further connection resistance is provided for the parison sag.

(5) The hollow sphere is adopted as the actuation positioning body, the diameter of the outer ring of the actuation positioning body and the radius of the outer ring of the interception convex body are both larger than the aperture diameter of the hole of the line through hole, so that the interception convex body and the actuation positioning body can not pass through the line through hole, stable two-way movement of the double-end filament bundle in the line through hole is ensured, when the actuation positioning body moves to be attached to the inner wall of the hollow core mold, the double-end filament bundle stops moving outwards, when the expansion film continues to expand outwards, the pricker moves back to the inner side of the expansion film through the film hole on the expansion film, and separation of the double-end filament bundle and the expansion film is realized.

(6) The sum of the gravity of the intercepting convex body and the pricking pin is smaller than the gravity of the actuating positioning body, so that in the initial state, the actuating positioning body is in a drooping state due to the gravity action of the actuating positioning body, the intercepting convex body is driven to be in a state of being attached to the outer wall of the hollow core mold, and the hollow core mold, the expansion film and the intercepting convex body can be quickly and accurately attached to each other by extracting gas when the expansion film is sleeved on the intercepting convex body.

(7) The inner ring diameter of the expansion film in the saturated expansion state is larger than the length of the double-end tows, when the expansion film does not reach the saturated expansion, the positioning body is triggered to move to the hole of the line through hole, the expansion film and the double-end tows start to be separated, the film hole in the expansion film is exposed, and the gas in the later period can flow to the parison through the film hole, so that the parison expands until the parison is attached to the cavity wall.

(8) The split injection mold is closed outside the bulge membrane in S2, i.e.: when the injection mold is closed, the upper end of the expansion film and the hollow core mold can be clamped tightly by the mold, so that the upper end of the expansion film and the hollow core mold are not easy to separate and generate air leakage in the expansion process of the expansion film, and the expansion film can be ensured to be expanded normally.

Drawings

FIG. 1 is a block flow diagram of the present invention;

FIG. 2 is a schematic diagram showing the structural change in the front side of the present invention when the inflatable membrane is fixed;

FIG. 3 is a schematic front view of the present invention after the mold is switched;

FIG. 4 is a schematic view of the structure at A in FIG. 3;

FIG. 5 is a schematic view of the local structural change of the present invention when the hair expansion mask is applied;

FIG. 6 is a schematic front view of the blow-molded expansion process of the present invention;

fig. 7 is a schematic front view of the blow-molding expansion process according to the present invention.

The reference numbers in the figures illustrate:

1 hollow core mould, 101 thread through holes, 2 expanding films, 31 block convex bodies, 32 prickers, 33 inelastic connecting wires and 34 actuating positioning bodies.

Detailed Description

The drawings in the embodiments of the invention will be combined; the technical scheme in the embodiment of the invention is clearly and completely described; obviously; the described embodiments are only some of the embodiments of the invention; but not all embodiments, are based on the embodiments of the invention; all other embodiments obtained by a person skilled in the art without making any inventive step; all fall within the scope of protection of the present invention.

In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top/bottom", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "disposed," "sleeved/connected," "connected," and the like are to be construed broadly, e.g., "connected," which may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Example (b):

referring to fig. 1, 2 and 3, a crack-resistant multi-step resin injection blow molding process includes the following steps:

s1, film covering: sleeving the expansion film 2 on the outer side of the hollow microporous male die from bottom to top, and preliminarily fixing the upper end opening of the expansion film 2 at the outer end of the hollow microporous male die through an adhesive;

s2, depressurizing and compacting: putting the hollow microporous male die into a split injection die, then closing and fixing the die, and pumping out air in the hollow microporous male die to ensure that the expanded membrane 2 is tightly attached to the outer surface of the hollow microporous male die, wherein double-end tows on the hollow microporous male die penetrate through the expanded membrane 2 to generate membrane holes;

s3, injection: injecting a molten resin into an injection mold to form a parison;

s4, converting the die: taking the parison and the hollow microporous male mold out of the injection mold and placing the parison and the hollow microporous male mold into a split blow mold, and then closing and fixing the mold;

s5, blow molding and expanding: air is sent into the hollow microporous male die, the air is dispersed outwards through micropores on the hollow microporous male die, and the double-end filament bundles, the expanded membrane 2 and the parison are expanded outwards together;

s6, multiple separation: in the expansion process, the double-end filament bundle, the expansion film 2 and the parison are separated from each other in sequence, and finally the parison is attached to the cavity wall of the blow molding die except the bottle neck;

and S7, releasing air in the hollow micropore convex mold after pressure maintaining, cooling and shaping, and opening the blow molding mold to take out the plastic part.

Referring to fig. 6 and 7, S6 specifically includes the following steps:

s6.1, primary separation: when the double-end tows move to the limit point, the double-end tows are separated from the expansion film 2, the film holes in the expansion film 2 are exposed, and the expansion film 2 and the parison continue to expand outwards;

s6.2, double separation: when the expansion film 2 expands to the maximum degree, gas flows to the parison through the film holes on the expansion film 2, the expansion film 2 is separated from the parison, and the parison continues to expand outwards until the parison is attached to the cavity wall of the blow mold.

Before a re-separation process occurs, the double-end tows seal membrane holes in the expansion membrane 2, the double-end tows, the expansion membrane 2 and the parison expand outwards together under the action of air pressure, and the expansion membrane 2 expands uniformly on the parison to enable the parison to expand uniformly.

Referring to fig. 3 and 4, the hollow microporous male mold comprises a hollow core mold 1, a plurality of uniformly distributed thread through holes 101 are formed in the hollow core mold 1, a plurality of double-headed tows and the plurality of thread through holes 101 are identical in number and are in one-to-one correspondence, the double-headed tows penetrate through the inside of the thread through holes 101 and respectively extend to two sides of the hollow core mold 1, the double-headed tows are driven by the expansion film 2 and the parison to move in the outward expansion process of the expansion film 2 and the parison, so that the double-headed tows move outwards along the thread through holes 101, and the expansion film 2 and the double-headed tows are both made of high temperature resistant materials.

Referring to fig. 5, the double-end filament bundle includes a block convex body 31 and an actuating positioning body 34, the block convex body 31 is located at the outer side of the hollow core mold 1, the actuating positioning body 34 is located at the inner side of the hollow core mold 1, the actuating positioning body 34 is made of a light material, a plurality of inelastic connecting wires 33 are fixedly connected between the block convex body 31 and the actuating positioning body 34, the inelastic connecting wires 33 are slidably connected with the inner side of the wired through hole 101, the block convex body 31 is in a hollow hemispherical shape, the inelastic connecting wires 33 are fixedly connected with the inner surface of the block convex body 31, the outer surface of the block convex body 31 is fixedly connected with a plurality of uniformly distributed pricking pins 32, when the expansion film 2 is sleeved at the outer side of the hollow core mold 1, the block convex body 31 is located between the hollow core mold 1 and the expansion film 2, during the process of extracting the gas in the hollow core mold 1, the gas in the hollow core mold 1 moves upward from the port, under the action of the, the positioning body 34 is driven to move upwards along with the blank and the intercepting convex body 31 is driven to move through the inelastic connecting wire 33, so that the intercepting convex body 31 is more tightly attached to the outer wall of the hollow core mould 1, meanwhile, the expanding film 2 is gradually attached to the outer wall of the hollow core mould 1 under the action of air pressure, when the expanding film 2 and the intercepting convex body 31 are close to each other and contact, the puncture needle 32 punctures the expanding film 2 to form a film hole, the puncture needle 32 passes through the film hole to extend to the outer side of the expanding film 2, the expanding film 2 is tightly attached to the intercepting convex body 31, therefore, when the molten resin is injected, the molten resin is filled between the expanding film 2 and the injection mould, the puncture needle 32 goes deep into the molten resin, so that in the process of moving the blank and the hollow core mould 1, on one hand, the contact surface between the blank and the expanding film 2 can be increased through the intercepting convex body 31, namely, the friction force applied when the blank sags is increased, the hemispherical surface of the truncated convex body 31 provides support resistance to parison sag, and the intimate contact between the spike 32 and the interior of the parison provides a tight bond between the parison and the tow of dual ends, further providing bond resistance to parison sag.

Referring to fig. 5, the priming positioning body 34 is a hollow sphere, the diameter of the outer ring of the priming positioning body 34 and the radius of the outer ring of the interception convex body 31 are both larger than the aperture diameter of the thread through hole 101, so that both the interception convex body 31 and the priming positioning body 34 cannot pass through the thread through hole 101, stable bidirectional movement of the double-end filament bundle in the thread through hole 101 is ensured, when the priming positioning body 34 moves to be attached to the inner wall of the hollow core mold 1, the double-end filament bundle stops moving outwards, so that when the expansion film 2 continues to expand outwards, the puncture needle 32 moves back to the inner side of the expansion film 2 through the film hole on the expansion film 2, and separation of the double-end filament bundle and the expansion film 2 is realized.

Referring to fig. 2, the sum of the gravity of the intercepting convex body 31 and the needle 32 is smaller than the gravity of the actuating positioning body 34, so that in the initial state, due to the gravity action of the actuating positioning body 34, the actuating positioning body 34 is in a drooping state, and the intercepting convex body 31 is driven to be in a state of being attached to the outer wall of the hollow core mold 1, thereby ensuring that when the expansion film 2 is sleeved, the close attachment among the hollow core mold 1, the expansion film 2 and the intercepting convex body 31 can be rapidly and accurately realized by extracting gas.

Referring to fig. 6, the diameter of the inner ring of the expansion film 2 in the saturated expansion state is greater than the length of the double-end filament bundle, so that when the expansion film 2 does not reach the saturated expansion, the positioning body 34 is actuated to move to the orifice of the through-line hole 101, the expansion film 2 and the double-end filament bundle start to separate, the film hole on the expansion film 2 is exposed, and the gas in the later stage can flow to the parison through the film hole, so that the parison expands until the parison is attached to the wall of the cavity.

The split injection mold is closed outside the bulge membrane 2 in S2, i.e.: when the injection mold is closed, the upper end of the expansion film 2 and the hollow core mold 1 can be clamped tightly by the mold, so that the upper end of the expansion film 2 and the hollow core mold 1 are not easy to separate to generate air leakage in the expansion process of the expansion film 2, and the expansion film 2 can be ensured to be expanded normally.

According to the invention, the double-end filament bundles are arranged on the hollow core mould 1, and the outer end of the hollow core mould 1 is tightly attached with the expansion film 2, so that in the parison injection molding process, the expansion film 2 and the double-end filament bundles are deeply contacted with the parison in a large area, the friction force and the supporting resistance of the parison during automatic sagging can be greatly improved, the dead weight sagging condition of the parison is reduced, the uniformity of the wall thickness of the parison is improved, the parison is not easy to crack during expansion, and in the parison blow molding expansion process, the airflow pressure is uniformly and comprehensively acted on the parison by outward expansion of the expansion film 2 and the double-end filament bundles, so that the local cracking condition of the parison caused by airflow impact is greatly reduced, and the quality of a finished product is further ensured.

The above; but are merely preferred embodiments of the invention; the scope of the invention is not limited thereto; any person skilled in the art is within the technical scope of the present disclosure; the technical scheme and the improved concept of the invention are equally replaced or changed; are intended to be covered by the scope of the present invention.