Wuhan Hyundai Blow Molding
DATE：2020/12/25 9:00:55 / READ： / SOURCE：This station
Wuhan Hyundai Blow Molding
The general principle of blow molding can be summarized as blowing compressed air into the molten parison to inflate it laterally, close to the surface of the mold cavity, and form a hollow product after cooling. Therefore, blow molding generally refers to the molding method of hollow containers.
There are many types of blow molding methods and blow molding machines. There is no unified classification method. The following classification methods are commonly used: 1. According to the production method of parisons, there are extrusion blow molding, injection blow molding, and two Segment blow molding. ②According to the blowing method: there are up blowing, down blowing, horizontal blowing and so on. ③According to the moving direction of the mold after clamping the parison: vertical lifting, horizontal moving, oblique lifting, non-moving, rotary movement, etc. www.handern.com Solar cell back sheet film equipment
This section only introduces the most widely used extrusion blow molding method.
The so-called extrusion blow molding method uses an extruder to produce a hot parison and then blow molding. Extrusion blow molding can be divided into two methods according to the pressing conditions of the parison.
1. Extrusion blow molding head and auxiliary machine
Auxiliary machines for extrusion blow molding include molds, mold clamping brackets, air nozzles, mold clamping devices, circuits, oil circuits, air circuit systems, etc. Only focus on the machine hole, storage tank, mold and clamping device.
1. Machine head and storage tank
(1) Head type In general extrusion blow molding, the extruder is a horizontal device. Since the parison is extruded vertically downwards, a right-angle die must be used to turn the resin flow 90 degrees from horizontal to vertical. . Due to the change of the flow direction of the molten resin, there is a pressure difference and a difference in flow rate. Therefore, the right angle die must be designed to make the flow rate of the molten resin uniform before it reaches the die. The hollow forming head should have the following conditions:
①There is no stagnant part in the machine head, and it can run stably for a long time. This requires that the resin flow channel does not produce dead spots and avoid a sharp change in the cross-sectional area of the flow channel. At the same time, in order to minimize the friction between the resin and the machine head, the die should generally be chrome-plated.
②The strength drop and appearance defects caused by the compound line should be avoided. www.handern.com Solar cell back sheet film equipment
③The wall thickness of the parison is uniform.
④Overcome the sagging phenomenon of the parison.
⑤ Avoid the pulsation of parison extrusion.
With the development of the application field of hollow products, various types of heads have appeared from small to large, simple to complex. Among them, the storage head has developed rapidly in the past 20 years, and is widely used in the production of products above 5 liters. The type of die is similar to the structure and die for blown film, including mandrel type, cross type and spiral type.
(2) The structural characteristics and application range of various handpieces lists the advantages and disadvantages and application ranges of various handpieces.
(3) The principle of electronic program control of the storage head control. With technological progress, both continuous extruders and storage cylinder extruders have successively adopted electronic program controllers. Especially for large and medium-sized material blow molding machines, the application of multi-point control is increasing.
(4) Special die
① When the cross-section of the die-molded product is rectangular or elliptical, the use of round blanks will inevitably cause unevenness in thickness. In order to solve this problem, two advantageous methods can be adopted: one is to slot the die sleeve or core mold to thicken the part of the parison with a larger blow-up ratio; the other is to use a round parison. When the product is particularly flat, a non-circular die that matches the shape of the parison with the cross-section of the product can be used. When using, pay attention to making the inflation ratio smaller. www.handern.com Solar cell back sheet film equipment
② Die for multi-layer parison is used to produce multi-layer containers of different materials or the same material and different colors. The most common are 2-layer and 3-layer die. Two kinds of resins flow into the inner core mold respectively from their respective extruders, and then one is introduced into the flow channel between the outer core mold and the inner core mold, and the other is introduced into the flow channel between the die sleeve and the outer core mold. At the die lip, the two merge into a fused double-layer blank.
2. Mould
The ideal mold should be as symmetrical as possible. However, asymmetric products are often popular in the market. Therefore, we must fully consider the design of the mold. The general design principles are: ①The transition of edges and corners should have a larger radius to prevent stress concentration; ②The side wall is designed with wave-like blade ribs to improve impact resistance and toughness: ③The cut on the parting surface should ensure the fastness of welding. ④Use a round surface to avoid warping; ⑤The big barrel should be easy to stack, stack, and transport
(1) Mold classification The types of hollow forming molds can be roughly divided into equidistant open-yang molds, hinge molds, three-open molds and special molds.
① Opening and closing molds at equal distances There are two types of mold opening and closing directions: horizontal and vertical. The mainstream is the equidistant opening and closing molds in the horizontal direction.
②Hinge-type mold connects the two molds with hinges (folding pages). The hinge is used as a fulcrum for arc opening and closing. When the rotary mold clamping device rotates, the cam is automatically closed. In this case, twisting is often used. Chain mold. The hinged mold has a simple structure and can be self-locked when the moment arm is extended. The disadvantage is that the wear of the hinge will cause inaccurate mold clamping.
③Three-open mold hollow products should be easy to stack and palletize, and place them stably. When designing the shape, the inner side of the bottom of the round container should be recessed. In this recessed part, when the mold is opened to take the product, there will be a scratch on the bottom of the mold. In general, if the depth of the bottom recess is designed within the shrinkage range of the product, there is no problem. When the scrap edge is cut deeper, scrap may appear. To this end, three-opening molds must be used. In addition, molds that are complicated in shape and cannot be opened and closed on the left and right. In order to unload products, three-open molds can also be used. Note: The hydraulic pressure at the bottom or other parts of the three-open mold must be the projection area of the bottom and other parts x the blowing pressure, otherwise the mold will open after blowing.
④Special molds are designed and manufactured for various applications. Such as non-fusion line molds, trimming molds, automatic sealing molds, double-wall product molds, etc. www.handern.com Solar cell back sheet film equipment
(2) Mold manufacturing materials
(3) Die incision change the incision angle according to the plastic type, molding temperature, crystal shape and required wall thickness, etc.
It is easy to cut when the cut is thin and the angle is sharp, but the bottom of the molded product is not well welded, and even the bottom part of the material is too thin or cracked. Therefore, the incision should be provided with ribs. The cut length of the bottom mold of the stable product is not more than 80% of the bottom diameter of the product.
The general principle of blow molding can be summarized as blowing compressed air into the molten parison to inflate it laterally, close to the surface of the mold cavity, and form a hollow product after cooling. Therefore, blow molding generally refers to the molding method of hollow containers.
There are many types of blow molding methods and blow molding machines. There is no unified classification method. The following classification methods are commonly used: 1. According to the production method of parisons, there are extrusion blow molding, injection blow molding, and two Segment blow molding. ②According to the blowing method: there are up blowing, down blowing, horizontal blowing and so on. ③According to the moving direction of the mold after clamping the parison: vertical lifting, horizontal moving, oblique lifting, non-moving, rotary movement, etc. www.handern.com Solar cell back sheet film equipment
This section only introduces the most widely used extrusion blow molding method.
The so-called extrusion blow molding method uses an extruder to produce a hot parison and then blow molding. Extrusion blow molding can be divided into two methods according to the pressing conditions of the parison.
1. Extrusion blow molding head and auxiliary machine
Auxiliary machines for extrusion blow molding include molds, mold clamping brackets, air nozzles, mold clamping devices, circuits, oil circuits, air circuit systems, etc. Only focus on the machine hole, storage tank, mold and clamping device.
1. Machine head and storage tank
(1) Head type In general extrusion blow molding, the extruder is a horizontal device. Since the parison is extruded vertically downwards, a right-angle die must be used to turn the resin flow 90 degrees from horizontal to vertical. . Due to the change of the flow direction of the molten resin, there is a pressure difference and a difference in flow rate. Therefore, the right angle die must be designed to make the flow rate of the molten resin uniform before it reaches the die. The hollow forming head should have the following conditions:
①There is no stagnant part in the machine head, and it can run stably for a long time. This requires that the resin flow channel does not produce dead spots and avoid a sharp change in the cross-sectional area of the flow channel. At the same time, in order to minimize the friction between the resin and the machine head, the die should generally be chrome-plated.
②The strength drop and appearance defects caused by the compound line should be avoided. www.handern.com Solar cell back sheet film equipment
③The wall thickness of the parison is uniform.
④Overcome the sagging phenomenon of the parison.
⑤ Avoid the pulsation of parison extrusion.
With the development of the application field of hollow products, various types of heads have appeared from small to large, simple to complex. Among them, the storage head has developed rapidly in the past 20 years, and is widely used in the production of products above 5 liters. The type of die is similar to the structure and die for blown film, including mandrel type, cross type and spiral type.
(2) The structural characteristics and application range of various handpieces lists the advantages and disadvantages and application ranges of various handpieces.
(3) The principle of electronic program control of the storage head control. With technological progress, both continuous extruders and storage cylinder extruders have successively adopted electronic program controllers. Especially for large and medium-sized material blow molding machines, the application of multi-point control is increasing.
(4) Special die
① When the cross-section of the die-molded product is rectangular or elliptical, the use of round blanks will inevitably cause unevenness in thickness. In order to solve this problem, two advantageous methods can be adopted: one is to slot the die sleeve or core mold to thicken the part of the parison with a larger blow-up ratio; the other is to use a round parison. When the product is particularly flat, a non-circular die that matches the shape of the parison with the cross-section of the product can be used. When using, pay attention to making the inflation ratio smaller. www.handern.com Solar cell back sheet film equipment
② Die for multi-layer parison is used to produce multi-layer containers of different materials or the same material and different colors. The most common are 2-layer and 3-layer die. Two kinds of resins flow into the inner core mold respectively from their respective extruders, and then one is introduced into the flow channel between the outer core mold and the inner core mold, and the other is introduced into the flow channel between the die sleeve and the outer core mold. At the die lip, the two merge into a fused double-layer blank.
2. Mould
The ideal mold should be as symmetrical as possible. However, asymmetric products are often popular in the market. Therefore, we must fully consider the design of the mold. The general design principles are: ①The transition of edges and corners should have a larger radius to prevent stress concentration; ②The side wall is designed with wave-like blade ribs to improve impact resistance and toughness: ③The cut on the parting surface should ensure the fastness of welding. ④Use a round surface to avoid warping; ⑤The big barrel should be easy to stack, stack, and transport
(1) Mold classification The types of hollow forming molds can be roughly divided into equidistant open-yang molds, hinge molds, three-open molds and special molds.
① Opening and closing molds at equal distances There are two types of mold opening and closing directions: horizontal and vertical. The mainstream is the equidistant opening and closing molds in the horizontal direction.
②Hinge-type mold connects the two molds with hinges (folding pages). The hinge is used as a fulcrum for arc opening and closing. When the rotary mold clamping device rotates, the cam is automatically closed. In this case, twisting is often used. Chain mold. The hinged mold has a simple structure and can be self-locked when the moment arm is extended. The disadvantage is that the wear of the hinge will cause inaccurate mold clamping.
③Three-open mold hollow products should be easy to stack and palletize, and place them stably. When designing the shape, the inner side of the bottom of the round container should be recessed. In this recessed part, when the mold is opened to take the product, there will be a scratch on the bottom of the mold. In general, if the depth of the bottom recess is designed within the shrinkage range of the product, there is no problem. When the scrap edge is cut deeper, scrap may appear. To this end, three-opening molds must be used. In addition, molds that are complicated in shape and cannot be opened and closed on the left and right. In order to unload products, three-open molds can also be used. Note: The hydraulic pressure at the bottom or other parts of the three-open mold must be the projection area of the bottom and other parts x the blowing pressure, otherwise the mold will open after blowing.
④Special molds are designed and manufactured for various applications. Such as non-fusion line molds, trimming molds, automatic sealing molds, double-wall product molds, etc. www.handern.com Solar cell back sheet film equipment
(2) Mold manufacturing materials
(3) Die incision change the incision angle according to the plastic type, molding temperature, crystal shape and required wall thickness, etc.
It is easy to cut when the cut is thin and the angle is sharp, but the bottom of the molded product is not well welded, and even the bottom part of the material is too thin or cracked. Therefore, the incision should be provided with ribs. The cut length of the bottom mold of the stable product is not more than 80% of the bottom diameter of the product.
Author：admin