CN212737062U - PVC blown film equipment - Google Patents

Abstract

The invention discloses PVC film blowing equipment which mainly comprises an extruder, a net exchanging device, a machine head, a cooling device, a traction device, a cutting device, a spreading device, a coiling device and a plurality of auxiliary devices, wherein a central feeding type machine head is adopted, and a heat exchanging device is additionally arranged in the machine head; a plurality of air cooling and water cooling devices are added; a small amount of particulate opening agent may be injected at the metered delivery gas device of the handpiece. The PVC film blowing equipment adopts the flow channel of the central feeding type machine head to optimize the disadvantages of poor PVC fluidity and unstable heating, strengthens the cooling effect by adopting a plurality of cooling and heat exchange measures, avoids the influence of temperature change on the final forming of the film and ensures the film discharging quality. In addition, the use of part of the reagent also ensures the opening performance of the PVC film, so that the blown film product has good plasticizing degree, uniform thickness, high transparency and glossiness and better quality.

Description

PVC blown film equipment

Technical Field

The invention belongs to the technical field of film blowing, and particularly relates to PVC film blowing equipment.

Background

The working principle of film blowing is as follows: after the resin is melted and plasticized by an extruder, the resin is extruded into a cylindrical film tube from an annular gap of a machine head, and a certain amount of compressed air is blown from an air inlet below the machine head to transversely blow the film tube. At the same time, the longitudinal stretching is continuously performed by means of the drawing rolls, and the air blown out through the cooling air ring is cooled. The fully cooled film tube is folded by a herringbone plate to form a double-folded film, the double-folded film can be cut after being drawn by a drawing roll, and finally the double-folded film enters a curling device at a constant linear speed. After curling for a certain time, cutting to form a film roll, and packaging and then leaving the factory.

Compared with a PE film, the PVC film has great advantages in the aspects of mechanical property, heat preservation property, barrier property, price and the like, and due to the surplus of domestic PVC capacity, the contradiction of the surplus of the capacity can be effectively coped with by taking PVC as a raw material, so that the waste of resources is avoided. The PVC film has the characteristics of good transparency, flame retardance, moisture resistance, water resistance, excellent insulating property, strong antifouling property and the like, and is widely applied to various industries such as building materials, packaging, medicines and the like. The traditional PE film blowing equipment has the defects that the machine head is not suitable for PVC film production, PVC has the disadvantages of poor thermal stability, poor flowability, high viscosity and the like, so that the plasticizing degree of a molten PVC material is not high, the film discharging effect is not ideal, the phenomena of uneven film thickness and the like are easy to occur, the flatness and the uniformity of the film cannot be ensured, and the film blowing quality is low.

Disclosure of Invention

The invention aims to solve the problems in the PVC film blowing process, and provides a PVC film blowing equipment scheme, so that the disadvantages of poor flowability, poor thermal stability, unsatisfactory plasticizing effect and the like of a PVC material are effectively optimized, the cooling effect in the film blowing process is enhanced, the stability and uniformity of the PVC film blowing process are ensured, and the produced film product has the advantages of good plasticizing effect, high transparency and glossiness, uniform thickness and good quality.

A PVC film blowing device mainly comprises an extruder, a screen changing device, a machine head, a cooling device, a traction device, a cutting device, a spreading device, a coiling device and a plurality of auxiliary devices. In the film blowing equipment, the screw extruder can be a single screw extruder and is suitable for blow molding of polyvinyl chloride, and the single screw extruder consists of a transmission system, an extrusion system, a heating and cooling system and a control system. The extruder carries, plastify, homogenization and build pressure to the PVC material, enters into the filtration and trades the net device after the material is extruded uniformly from the extruder, becomes linear motion with the material by rotary motion, prevents impurity and not the complete material of plastify and passes through, has increased the backpressure of material stream, makes the goods more closely knit. The filter screen is the stainless steel net, has avoided the corruption of polyvinyl chloride to its metal material, and flow distribution plate to screw head distance should not be too big, otherwise can store up the material, but also can not the undersize, is unfavorable for the melt evenly to pass through the flow distribution plate, makes the volume of screw head and air current board equal or be less than the volume of a screw groove of homogenization section slightly usually, for the quality of guaranteeing the PVC blown film and the work efficiency of extruder, chooses for use the manual flange formula of not shutting down and trades the net device, trades the net device and should avoid having the dead angle and lead to the stagnant flow of material.

The machine head part of the equipment is a central feeding type machine head, a flow channel of the machine head is reasonably designed, the flow channel of the machine head comprises a flow channel inlet section, a flow channel extension section and a flow channel straight section, the machine head is uniformly fed, and a middle core rod is not subjected to lateral force, so that the thickness error of a film is small; the flow path of the flow channel is short, the flow channel is smooth, and the material is prevented from stagnating in the flow channel and being decomposed; the straight section of the film outlet of the machine head is kept with a certain length to ensure that the pressure at the outlet is suitable for blowing out a large-folding-diameter film, the discharging is uniform, the pressure fluctuation of the machine head is small, and the film forming precision is higher. The design of the machine head can effectively deal with the defects of poor PVC flowability and poor thermal stability, and the quality and effect of the film are ensured. In addition, a metering device is provided on the handpiece, by means of which air can be blown into the center of the interior of the handpiece. The heat exchange device is arranged at the center of the head die, and when the head die works, the heat exchanger in the head absorbs high-temperature gas in the membrane tube and discharges the high-temperature gas from the air outlet of the head, so that the temperature in the membrane bubble of the membrane cannot be too high. Some granular opening agents can be injected into the quantitative conveying device of the machine head, and the opening agents are sprayed on the inner surface of the film along with air flow through blowing, so that the problems that the film products are not easy to separate and are adhered together, the opening is difficult and the brightness is not high and the like can be effectively prevented, and the opening function is realized. The film bubble is in a semi-flowing state or a plastic state at a higher temperature just after the film bubble leaves the machine head, the time for pulling the clamping roller is shorter, and the phenomena of adhesion and non-uniformity are easy to occur. A first cooling air ring is arranged above the straight section of the machine head, the first air ring is an air ring which is cooled externally, cold air is blown to the film bubble along the periphery of the film in a certain direction, and the outlet of the first air ring is rotatable, so that the cooling effect of the film bubble at the outlet is ensured. The air inlet device of the cooling air ring is connected with a refrigeration thermostatic device, namely an air cooler, air which is evaporated, absorbed and cooled to pass through is evaporated in a cold air heat exchanger, a blower of a film blowing unit extracts low-temperature cold air cooled by the cold air heat exchanger through an air inlet pipe and then sends the low-temperature cold air into the air ring of the film blowing machine to cool the film bubble just blown out from a die head, so that the film bubble is stable and uniform in thickness, and the transparency and the glossiness are increased. The air outlet of the air cooler is provided with a sensor, when the temperature changes, the temperature at the outlet of the film bubble is kept constant under the feedback action of the control system, the phenomenon of uneven film thickness caused by the change of the temperature is avoided, and the film bubble is stably shaped.

A first cooling air ring is arranged above the straight section of the machine head, the first air ring is an externally cooled air ring, cold air is blown to the film bubble along the periphery of the film in a certain direction, and an outlet of the first air ring can rotate. The air inlet device of the cooling air ring is connected with an air cooler, and cooled air is sent into the air ring of the film blowing machine during operation. The air outlet of the air cooler is provided with a sensor, and the temperature at the outlet of the film bubble is ensured to be constant through the feedback action of the control system. A water cooling device is arranged at the upper drawing roller to strengthen the cooling film and the drawing roller. In consideration of the cooling effect, the cost price and the applicable range, the air rotary type air ring cooling by an external cooling method is adopted, the diameter of the air ring is 1.3-1.5 times of the diameter of the neck mold, the blow-out angle of the air ring is 40-60, and the uniformity of the thickness can be conveniently controlled by adjusting the air quantity.

The well-type bubble stabilizer is arranged on the extension of the film tube, the bubble stabilizer is arranged above the cooling air ring, and the bubble stabilizer needs to be in contact with the film bubble, so that the stability of the film in the blow molding process can be improved, the thickness error of the film is reduced, and the curling quality of the film is improved. Because the surface of the membrane tube is sticky, the inner side of the bubble stabilizer can be coated with Polytetrafluoroethylene (PTFE) which has the minimum surface tension in solid materials, does not adhere any substance and has the excellent high-temperature and low-temperature resistance. And a second cooling air ring is arranged above the bubble stabilizer, so that the cooling effect is further enhanced, and the quality of the film is ensured.

A herringbone plate is arranged above the bubble stabilizer and at the position close to the rear part of the membrane tube to gradually fold the cylindrical membrane into a plane shape, and further to cool the membrane and stabilize the membrane tube. And pressing rollers are arranged above the herringbone plate, and a channel for a film to pass through is formed between the pressing rollers, so that the film can be conveniently flattened. After the film comes out, the film is pulled by the upper pulling roll, the thickness of the film is controlled by adjusting the pulling speed, so that the film tube is folded from a tubular shape without causing wrinkles, the air leakage of the film is prevented, and the constant inflation ratio is ensured. The traction roller can be a steel roller and a rubber roller at the same time, and the rubber hardness of the rubber roller is preferably controlled to be 50-60 ℃. Because the temperature of the upper traction roller is higher, a water cooling device is arranged to enhance cooling, and the cooling effect is obviously enhanced when the film passes through the water cooling device of the upper traction roller. The cooled double-layer film is conveyed to a sectioning device by a traction roller, the sectioning device is in bilateral edge cutting type sectioning, two small openings are firstly cut at two sides of the film by a sectioning knife, the two small openings are blown inwards by an air blowing opening extending head to enlarge the opening of the film, then the two layers of films are separated by a conical guide device, and the films are stably drawn after being cut by a film stabilizing cylinder. The split film is changed into two separated layers, the width of each single-layer film is the same as the folding diameter of the original film tube, and the thickness of each single-layer film is half of the original thickness. And the two single-layer films are conveyed to an unfolding device by the traction of a lower traction roller, the unfolding device consists of two rollers rotating in different directions, and the two single-layer PVC films are respectively conveyed to a coiling device. The coiling speed is required to be matched with the speed of a traction wire during coiling and does not change along with the change of the diameter of a film coil, the coiling device is a multi-station multi-driving-roller coiling device and consists of two groups of three different coiling rollers rotating in the same direction, two single-layer films of the unwinding device are separately coiled, so that the automatic coiling of the film materials can be realized, a manipulator is arranged above the coiling roller, and the automatic cutting and coiling of the film materials can be realized through a regulating and controlling system. And after a roll of the membrane material is rolled, cutting the membrane material, and taking out the rolled membrane material.

Compared with the prior art, the invention has the advantages of obviously strengthening the cooling measure in the production process of the PVC film, optimizing the plasticizing effect of the PVC material and better overcoming the defects of poor thermal stability, poor fluidity and the like of the PVC. The runner of the central feeding type machine head after reasonable design optimizes the disadvantages of poor PVC flowability and unstable heating, strengthens the cooling effect by multiple cooling and heat exchange measures, avoids the influence of temperature change on the final forming of the film, and ensures the film discharging quality. In addition, the use of part of the reagent also ensures the opening performance of the PVC film, so that the blown film product has good plasticizing degree, uniform thickness, high transparency and glossiness and better quality.

Drawings

FIG. 1 is a schematic structural diagram of a PVC film blowing apparatus according to the present invention.

Fig. 2 is an enlarged view of the cutting device 15 of fig. 1.

FIG. 3 is a schematic view of a flow channel structure of a film blowing head of the PVC film blowing device.

Fig. 4 is a cross-sectional view of fig. 3.

Fig. 5 is a top view of fig. 4.

Shown in the figure: 1. an extruder; 2. a screen changing device; 3. a machine head; 4. a heat exchange device; 5. cooling an air ring I; 6. a foam stabilizer; 7. a membrane tube; 8. a second cooling air ring; 9. a herringbone plate; 10. a pressure roller; 11. an upper pulling roll; 12. a water cooling device; 13. sealing the drying device; 14. an air cooler; 15. a sectioning device; 16. a lower traction roller; 17. a deployment device; 18. a take-up device; 19. a manipulator; 20. a frame; 21. a film stabilizing cylinder; 22. a support; 23. cutting a cutter; 24. an air blowing port; 25. a guide device; 3-1, a runner inlet section; 3-2, a flow channel extension section; 3-3, and a flow channel straight section.

Detailed Description

The drawings show the technical scheme and the embodiment of the invention, and the relevant details and the working principle of the invention are further described in the following with the help of the drawings.

As shown in figure 1, the PVC film blowing equipment comprises an extruder 1, a screen changing device 2, a machine head 3, a cooling air ring I5, a cooling air ring II 8, a water cooling device 12, a pressing roller 10, an upper traction roller 11, a lower traction device 16, a cutting device 15, a spreading device 17, a coiling device 18, a heat exchange device 4, an air cooler 14, a lambdoidal plate 9, a bubble stabilizer 6, a rack 20, a manipulator 19 and other auxiliary devices, wherein the cutting device 15 is structurally shown in figure 2 and comprises a film stabilizing cylinder 21, a support 22, a cutting knife 23, an air blowing port 24 and a guide device 25. The extruder 1 depends on the pressure and the shearing force generated by the rotation of the screw rod, so that the PVC material can be fully plasticized and uniformly mixed. The outlet of the extruder is connected with a screen changing device 2, the filter screen adopts a double-layer stainless steel screen, the distance from the flow distribution plate to the head of the screw rod is not too large, and the diameter of the screw rod is generally 0.1 time. A flange type filter screen replacing device is adopted, and the phenomenon that materials are stagnant due to dead angles is avoided by the aid of the filter screen replacing device. The machine head 3 is fixedly arranged above the screen changing device, the machine head adopts a center feeding type machine head which is reasonably designed, as shown in figure 3-5, a machine head flow passage comprises a flow passage inlet section 3-1, a flow passage extension section 3-2 and a flow passage straight section 3-3, a molten material is formed into a film tube with a certain shape, the film tube can be formed by blowing, and a certain pressure is generated to ensure that the molten material is uniformly and compactly extruded. A heat exchange device 4 is arranged at the center in the die head, and hot air in the membrane tube circulates through an air inlet and an air outlet of the die head, so that the temperature in the membrane tube is not too high. The air inlet of the machine head is provided with a certain amount of conveying device, air is blown to the air inlet through the device, and the opening agent is properly injected to be sprayed on the inner surface of the membrane tube through air flow before air blowing. Set up cooling wind ring one 5 above aircraft nose membrane bubble exit, the amount of wind size of cooling wind ring is by motor control, thereby the amount of wind size through adjusting motor rotational speed control air-blower guarantees the cooling effect of film, and the wind ring air outlet can rotate fine assurance film thickness's degree of consistency. The external air-cooler 13 of cooling wind ring one, the temperature of wind ring air inlet is reduced in the work of air-cooler, sets up the sensor on the air-cooler, prevents that temperature variation from causing the influence to the blown film, makes the diaphragm pipe steady, and thickness is even, and the film is stereotyped with higher speed. The extending part of the film tube is provided with a bubble stabilizer 6 above the cooling air ring, and the bubble stabilizer 6 adopts a well-type bubble stabilizer to improve the stability of the blown film and reduce the thickness error of the film. And simultaneously, the inner side of the foam stabilizer 6 is coated with PTFE material, so that the influence caused by contact between the surface of the foam stabilizer and the foam stabilizer due to over-adhesion of the surface is avoided. And a second cooling air ring 8 is also arranged above the bubble stabilizer, so that the cooling in the film blowing process is further increased. A herringbone plate 9 is arranged at the extending tail end of the membrane tube to stabilize the membrane bubble, the cylindrical membrane is folded into a plane shape, and the membrane is further cooled. PVC film bubble is further flattened by the pinch rolls 10 after passing through the herringbone plate, and is drawn and stretched by the upper drawing roll 11, a water cooling device 12 is arranged at the position, the upper drawing roll is arranged in a water cooling box, and the temperature of the film and the drawing roll at the position is reduced. When the film is conveyed to the sectioning device 15, a bilateral sectioning cutter is arranged, the double-layer film is sectioned from two sides, the double-layer film is conveyed to the unfolding device 17 by the traction of the lower traction roller 16 after the operations of air blowing, guiding, stabilizing and the like, the two single-layer films are unfolded and flattened by the unfolding device, the width of the flattened film is the same as the folding diameter of the original film, and the thickness of the flattened film is half of the original thickness. And finally, the film is dragged and conveyed to a coiling device 18, the coiling device adopts a multi-driving-roller multi-station surface friction coiling device, the structure is simple, the film coiling requirement can be met, and the coiling speed is matched with the speed of a traction line during coiling and does not change along with the change of the diameter of the film coil. Thereby the syntropy by the three batch roller of two sets of differences on the coiling apparatus is rotatory to realize beating the book to the automation of two individual layers PVC films, at rolling film in-process, the film rotates along with batch roller's rotation, film thickness can level and even, and the automatic cutout and the removal of membrane material can be realized to manipulator 19 on the batch roller, treats a roll shaping back, cuts off the membrane material, takes out the membrane material of beating the book, by the aftertreatment bagging-off at last, the shaping of work completion goods such as labelling, remark.

Claims (3)

1. The utility model provides a PVC blown film equipment, includes extruder, trades net device, aircraft nose, cooling device, draw gear, dissects the device, unwinding equipment, coiling apparatus and some auxiliary device, its characterized in that: a central feeding type machine head is adopted, and a heat exchange device is additionally arranged in the machine head; a plurality of air cooling and water cooling devices are added; a small amount of particulate opening agent is injected at the dosing gas device of the handpiece.

2. PVC blown film equipment according to claim 1, characterized in that: the center of the machine head mould is provided with a heat exchange device, a certain amount of gas conveying device is arranged on a machine head gas inlet, the device blows gas to the center of the interior of the machine head, and the heat exchange device absorbs high-temperature gas in the membrane tube and discharges the high-temperature gas from a machine head gas outlet.

3. PVC blown film equipment according to claim 1, characterized in that: a first cooling air ring is arranged above the straight section of the machine head, the first air ring is an externally cooled air ring, cold air is blown to the film bubble along the periphery of the film in a certain direction, and an outlet of the first air ring can rotate; an air inlet device of the cooling air ring is connected with an air cooler, a sensor is arranged at the air outlet of the air cooler, and the constant temperature at the position of a film bubble outlet is ensured through the feedback action of a control system; a water cooling device is arranged at the upper traction roller.

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