CN104943122A - Gas-assisted mouth die assembly - Google Patents

Abstract

An improved air-assisted die assembly for an extruder, which includes an air-free auxiliary section, an air chamber section, and an air-assisted section arranged coaxially and sequentially. The air-free auxiliary section is integrally formed with a flow channel , the other side of the airless auxiliary section corresponding to the flow channel tube is provided with a flow channel inlet, and the air chamber section is located in the central part axially and sequentially provided with a flow channel tube insertion hole and an air chamber cavity. The air chamber section is also provided with air holes radially connecting the air chamber cavity and the outer axial surface, and the air-assisted section is provided with air-assisted flow channel holes corresponding to the flow channel pipe, and the length of the flow channel pipe is longer than the The length of the air chamber section is less than the sum of the lengths of the air chamber section and the air-assisted section, and the other end of the flow channel pipe corresponding to the air-free auxiliary section passes through the flow channel pipe insertion hole and The air chamber cavity is inserted into the gas-assisted flow channel hole, and an air cushion is reserved between the radial periphery of the flow channel tube and the surrounding wall of the gas-assisted flow channel hole to form a gap.

Description

Gas-Assisted Die Components

technical field

The invention relates to the field of polymer molds, in particular to an improved gas-assisted die assembly of a polymer extruder.

Background technique

Extrusion products of polymer materials need to be melted and plasticized into a uniform melt through an extruder during the production and molding process, and finally discharged through a die to form a product. The die is made of steel, and the friction coefficient of steel is large. , when the high-temperature polymer melt passes through the polymer channel of the die, there will be adhesive friction with the wall of the die, which will affect the molding quality of the extruded product and increase energy consumption.

In response to the above situation, people improved the traditional die based on the traditional extruder, and proposed a gas-assisted extrusion molding technology. By controlling the injection of high-temperature gas into the die, a layer is formed between the inner wall of the die and the polymer. The extremely thin air cushion layer between the melts realizes the transition from sticky non-slip to non-stick complete slip extrusion. The key core of the aforementioned gas-assisted extrusion molding technology is the design of the gas-assisted die. At present, there are two commonly used methods at home and abroad, specifically:

1. Slit-type air intake mode. In this mode, the air intake direction of the high-pressure and high-temperature gas just entering the polymer flow channel is perpendicular to the flow direction of the polymer melt in the die. This kind of gas-assisted die mainly has the following problems:

(1) In the gas-assisted extrusion molding process, if the polymer melt passes through the die first, and then the gas passes through the die, the air inlet gap of the die will be blocked, and the polymer melt here needs to be melted with high-pressure gas. Only when the body is blown out can an air cushion layer be formed on the polymer melt and the wall of the die, thus increasing the complexity of the gas pressure regulation;

(2) After the gas-assisted extrusion molding is completed, once the gas is turned off first, and then the extruder is stopped to extrude the polymer melt, there will be a lot of polymer melt in the air inlet gap of the die and the air chamber of the die , once the time is long, the aggregate will solidify, and it is not easy to use high-pressure gas to blow off the polymer melt in the next gas-assisted extrusion molding, which will affect the stability of the air cushion layer. The mold needs to be disassembled when the aggregate is completely melted. The polymer melt inside is removed, reducing work efficiency;

(3) This method of die is only used for vertical downward extrusion of polymer melt. Once it is horizontally extruded (and in the polymer extrusion molding production industry, horizontal extrusion is mostly used), so the polymer melt The effect of gravity prevents the formation of the lower half of the air cushion, which leads to the failure of the process;

2. Pore air intake method, the problems of this method are as follows:

(1) Pores are easy to block and difficult to remove, thereby destroying the formation of the air cushion layer, so that this die can only be used for extrusion production of polymer melts with low viscosity;

(2) The pressure of the entire air cushion layer in the die is consistent, while the pressure of the polymer melt in this area is gradually reduced, so that the surface quality of the extrudate is easily reduced due to pressure imbalance.

Although the above two existing gas-assisted dies can overcome the adhesive friction between the polymer melt and the polymer flow channel of the die during the specific use of the traditional extrusion die, due to the high temperature and high pressure gas and the polymer melt The air intake direction when the body is just in contact with the extrusion direction of the polymer melt is perpendicular to each other, so it is easy to affect the quality of the polymer product and the stability of the gas-assisted extrusion process, and further research and improvement are necessary.

Contents of the invention

The invention provides an improved gas-assisted die assembly of an extruder. The main technical problem to be solved is: when the existing gas-assisted die is extruding a polymer product, when the two fluids are just in contact, the high temperature The gas flow direction is perpendicular to the extrusion direction of the polymer melt, which in turn affects the quality of the extruded product and the stability of the extrusion process.

Aiming at the deficiencies of the prior art, the present invention provides an air-assisted die assembly, which includes an air-assisted section, an air-chamber section, and an air-assisted section arranged coaxially in sequence, and the air-assisted section corresponds to the The central part of one side of the air chamber section is integrally formed with a flow channel tube, the flow channel tube is coaxial with the airless auxiliary section, and the other side of the airless auxiliary section corresponds to the flow channel tube. There is a flow channel inlet connected with the flow channel tube, and the air chamber section is located in the center part of the air chamber section, and is provided with a flow channel tube insertion hole and an air chamber cavity in sequence in the axial direction, and the flow channel tube insertion hole is connected with the flow channel tube Matching, the flow channel pipe socket communicates with the air chamber cavity and axially penetrates the air chamber section, and the air chamber section is also provided with an air hole radially connecting the air chamber cavity and the outer axial surface , the gas-assisted section is provided with a gas-assisted flow channel hole corresponding to the flow channel pipe, and the length of the flow channel pipe is greater than the length of the air chamber section and shorter than the length of the air chamber section and the gas-assisted section In sum, the other end of the flow channel tube corresponding to the air-free auxiliary section is inserted into the air-assisted flow channel hole through the flow channel tube insertion hole and the air chamber cavity, and the diameter of the flow channel tube An air cushion is reserved between the surrounding and the surrounding wall of the gas-assisted flow channel hole to form a gap.

Preferably, the airless assisted section, the air chamber section and the gas assisted section are all in the shape of a cylinder, and the adjacent axial end faces of the airless assisted section, the air chamber section and the air assisted section are sealed against each other. The air-assisted section, the air chamber section and the gas-assisted section are respectively provided with at least two positioning pin holes corresponding to the axial direction, and the non-air-assisted section, the air chamber section and the gas-assisted section are respectively provided with axially corresponding holes. At least three bolt installation holes, the positioning pin holes and the bolt installation holes are all staggered from the air holes.

Preferably, the flow channel inlet is conical, and the conical top of the conical flow channel inlet corresponds to the flow channel pipe, and the airless auxiliary section and the flow channel pipe form a funnel-shaped structure.

Preferably, the center of the gas-assisted flow channel hole deviates to one side relative to the central axis of the gas-assisted section, and the gas-assisted flow channel hole deviates horizontally downward relative to the central axis of the gas-assisted section.

Preferably: the flow channel pipe is 5mm longer than the air chamber section.

Preferably, the center of the gas-assisted flow channel hole deviates 0.25 mm to one side relative to the central axis of the gas-assisted section.

During the specific implementation of the present invention, the relative positioning of the airless auxiliary section, the air chamber section and the air auxiliary section is realized by inserting positioning pins in the positioning pin holes, and the airless auxiliary section, airless auxiliary section, The air chamber section and the gas-assisted section are installed horizontally at the outlet of the extruder head, and the adjacent axial end faces of the non-air-assisted section, the air chamber section and the air-assisted section are closely contacted by the extrusion of the mounting bolts. Sealed, the polymer melt extruded horizontally by the extruder enters the horizontally placed runner pipe through the runner inlet of the air-assisted section, and the polymer melt enters the air-assisted runner pipe through the delivery of the runner pipe At the same time, high temperature and high pressure gas can be filled into the air chamber cavity from the air hole, and the high temperature and high pressure gas passes through the air cushion from the air chamber cavity to form a gap in the gas-assisted flow channel hole. An air cushion with the same flow direction as the polymer melt flow is formed on the wall of the hole; when the gas-assisted section is installed, the gas-assisted runner hole deviates horizontally downward from the central axis of the gas-assisted section.

Compared with prior art, the beneficial effect of the present invention is:

1. Realized that the melt flow direction at the intersection of polymer melt and high-temperature gas is consistent with the gas flow direction, instead of being perpendicular to each other before, so that a uniform air cushion can be formed around the radial direction of the polymer melt extrudate, Improve the quality of the extrudate and improve the stability of the gas-assisted extrusion process;

2. The flow channel tube of the air-free section is longer than the air chamber section and inserted into the air-assisted flow channel hole. Due to the inertial force of the polymer melt during the extrusion process, the polymer melt flows to the opening direction of the gap formed by the air cushion. On the contrary, it effectively suppresses the reverse flow of the polymer melt along the pores when the high-temperature gas stops feeding;

3. In the process of extruding the new type of products, considering the influence of the gravity of the polymer melt, the center of the gas-assisted runner hole is horizontally deviated from the central axis of the gas-assisted section to increase the pressure of the lower half of the air cushion layer. Reserved space suppresses the blocking phenomenon of the lower half of the air cushion.

Description of drawings

Fig. 1 is a schematic cross-sectional view of the overall structure of the present invention.

FIG. 2 is an exploded schematic view of the cross-sectional structure of FIG. 1 .

Fig. 3 is a schematic diagram of a three-dimensional exploded structure of the present invention.

FIG. 4 is a schematic diagram of another angle of FIG. 3 .

Figure 5 is a schematic diagram of the end face structure of the gas-assisted section.

Detailed ways

A gas-assisted die assembly proposed by the present invention will be described in more detail below with reference to the accompanying drawings 1 to 5 and preferred embodiments.

Embodiment 1: The present invention provides an air-assisted die assembly, which includes an air-free auxiliary section 1, an air chamber section 2, and an air-assisted section 3 arranged coaxially and sequentially. The air-free auxiliary section 1 corresponds to the The central part of one side of the air chamber section 2 is integrally formed with a flow channel pipe 11, the flow channel pipe 11 is coaxial with the airless auxiliary section 1, and the airless auxiliary section 1 corresponds to the flow channel The other side of the tube 11 is provided with a flow channel inlet 12 communicating with the flow channel tube 11, and the air chamber section 2 is provided with a flow channel pipe insertion hole 21 and an air chamber cavity 22 in the axial direction at the central part. The flow channel tube insertion hole 21 matches the flow channel tube 11, the flow channel tube insertion hole 21 communicates with the air chamber cavity 22 and axially passes through the air chamber section 2, and the air chamber section 2 There is also an air hole 23 radially connecting the air chamber cavity 22 and the outer axial surface, and one end of the air hole 23 corresponding to the outer axial surface is provided with a connecting internal thread for inserting a high-temperature delivery air pipe. The gas-assisted section 3 A gas-assisted flow channel hole 31 is opened corresponding to the flow channel pipe 11, and the length of the flow channel pipe 11 is greater than the length of the air chamber section 2 and shorter than the length of the air chamber section 2 and the gas-assisted section 3 In sum, the other end of the flow channel pipe 11 corresponding to the air-free auxiliary section 1 is inserted into the air-assisted flow channel hole 31 through the flow channel pipe insertion hole 21 and the air chamber cavity 22, the An air cushion forming gap 32 is reserved between the radial periphery of the flow channel pipe 11 and the surrounding wall of the gas-assisted flow channel hole 31 .

In Embodiment 1 of the present invention, during specific implementation, the high-temperature and high-pressure gas first enters the air chamber cavity 22 through the air hole 23 for buffering and stabilization, and then intervenes with the polymer melt in the flow channel pipe 11 in the gas-assisted The flows in the same direction in the flow channel hole 31 converge, and the flow directions of the two fluids at the confluence are consistent. The gas is wrapped around the polymer melt and extruded together. The polymer melt and high-temperature and high-pressure gas merge and then enter the gas-assisted flow. Road hole 31, and extruded together.

Embodiment 2: On the basis of the above-mentioned embodiment 1, the airless auxiliary section 1, the air chamber section 2 and the air auxiliary section 3 are all in the shape of a cylinder, and the airless auxiliary section 1, the air chamber section 2 and the air The adjacent axial end surfaces of the auxiliary section 3 are in close contact with each other. The airless auxiliary section 1, the air chamber section 2 and the air-assisted section 3 are respectively provided with at least two positioning pin holes 4 corresponding to the axial direction. The airless auxiliary section 1, the air chamber section 2, and the air auxiliary section 3 are provided with at least three bolt installation holes 5 corresponding to the axial direction, and the positioning pin holes 4 and the bolt installation holes 5 are all staggered from the air hole 23 . In the process of assembly, in order to prevent misalignment of various parts, the entire die assembly is processed into a cylinder first, and two positioning pin holes are punched at the top horizontal line of the die assembly as a whole. 4 , and then cut it according to the height of each part, and process its internal structure. The close contact between the axially adjacent end faces of each part in the die assembly is realized by tightening the mounting bolts to the head of the extruder seal.

Embodiment 3: In combination with Embodiment 1 or Embodiment 2, the flow channel inlet 12 is conical, and the conical top of the conical flow channel inlet 12 corresponds to the flow channel pipe 11, and the no The gas-assisted section 1 and the channel tube 11 form a funnel-shaped structure, the channel tube 11 is a square tube, and the gas-assisted channel hole 31 is a square hole.

Embodiment 4: In the above embodiment, the center of the gas-assisted channel hole 31 deviates from the central axis of the gas-assisted section 3 to one side by 0.25 mm, and the gas-assisted section 3 is implemented in specific installation , the gas-assisted channel hole 31 deviates horizontally downward relative to the central axis of the gas-assisted section 3. In order to prevent the gravity factor of the polymer melt from causing the lower half of the air cushion to be blocked, the design of the gas-assisted section 3 The size of the lower half of the gas-assisted runner hole 31 is increased.

Embodiment 5: The flow channel pipe 11 is 5mm longer than the air chamber section 2. In order to avoid the reverse flow of the polymer melt into the air chamber cavity 22, the flow channel pipe 11 passes through the air chamber cavity 22 backward Insert 5mm into the gas-assisted flow channel hole 31, so that the opening direction of the air cushion forming gap 32 is the same as the flow direction of the polymer melt in the flow channel pipe 11. When the high-temperature gas stops conveying during the polymer melt extrusion process, When the structure of this embodiment is implemented, the polymer melt can continue to be extruded along the air-assisted runner hole under the action of extrusion inertia, thereby effectively avoiding the radial overflow of the polymer melt into the air inlet 23. .

In summary, the technical solution of the present invention can fully and effectively accomplish the above-mentioned purpose of the invention, and the structural principle and functional principle of the present invention have been fully verified in the embodiments, and can achieve the expected effect and purpose, and the present invention The embodiments of the invention can also be transformed according to these principles, therefore, the present invention includes all replacement contents within the range mentioned in the scope of the patent application. Any equivalent changes made within the patent scope of the present application all belong to the patent scope of the present application.

Claims (6)

1. the auxiliary mouth membrane module of gas, it is characterized in that: comprise coaxially be arranged in order setting without gas secondary segment, air chamber section and gas secondary segment, the described centre without described air chamber section side corresponding on gas secondary segment is integrated is provided with a flow-path tube, described flow-path tube is with described coaxial without gas secondary segment, the described opposite side without described flow-path tube corresponding on gas secondary segment offers the flow channel entry point be communicated with described flow-path tube, described air chamber section is positioned at centre and axially offers flow-path tube jack and air chamber successively, described flow-path tube jack and described flow-path tube match, described flow-path tube jack is communicated with described air chamber and axially runs through described air chamber section, described air chamber section also offers the pore of air chamber described in radial communication and outer axial face, the corresponding described flow-path tube of described gas secondary segment offers hole, gas secondary flow road, the length of described flow-path tube is greater than the length of described air chamber section, be less than the length sum of described air chamber section and described gas secondary segment, described flow-path tube is inserted in hole, described gas secondary flow road with the described other end corresponding without gas secondary segment through described flow-path tube jack and air chamber, be reserved with air cushion between the radial surrounding of described flow-path tube and the surrounding hole wall in hole, described gas secondary flow road and form gap.

2. the auxiliary mouth membrane module of a kind of gas according to claim 1, it is characterized in that: described without gas secondary segment, air chamber section and gas secondary segment all in cylindrical shape, between the described axial end adjacent without gas secondary segment, air chamber section and gas secondary segment, sealing paste leans on, describedly offer at least two dowel holes without axially corresponding respectively on gas secondary segment, air chamber section and gas secondary segment, describedly offer at least three bolt mounting holes without axially corresponding respectively on gas secondary segment, air chamber section and gas secondary segment, described dowel hole and bolt mounting holes all stagger described pore.

3. the auxiliary mouth membrane module of a kind of gas according to claim 2, it is characterized in that: described flow channel entry point is coniform, and corresponding with described flow-path tube in the conical top of cone shape described flow channel entry point, describedly form a funnel-shaped structure without gas secondary segment and flow-path tube.

4. the auxiliary mouth membrane module of a kind of gas according to claim 3, is characterized in that: the central axis of the relatively described gas secondary segment in center in hole, described gas secondary flow road departs to side, and the central axis level of the relatively described gas secondary segment in hole, described gas secondary flow road is deflected downwardly.

5. the auxiliary mouth membrane module of a kind of gas according to claim 4, is characterized in that: described flow-path tube is than described air chamber segment length 5mm.

6. the auxiliary mouth membrane module of a kind of gas according to claim 5, is characterized in that: the central axis of the relatively described gas secondary segment in center in hole, described gas secondary flow road departs from 0.25mm to side.