WO2017049808A1 - Film blowing production process - Google Patents
Film blowing production process Download PDFInfo
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- WO2017049808A1 WO2017049808A1 PCT/CN2016/000418 CN2016000418W WO2017049808A1 WO 2017049808 A1 WO2017049808 A1 WO 2017049808A1 CN 2016000418 W CN2016000418 W CN 2016000418W WO 2017049808 A1 WO2017049808 A1 WO 2017049808A1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
- B29C55/28—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of blown tubular films, e.g. by inflation
Definitions
- the invention belongs to the technical field of plastic film production processes, and in particular relates to a blown film production process.
- the plastic film can be produced by a blown film device using a blown film process, the blown film device is provided with an extrusion die, the extrusion die is provided with a circular extrusion port, and a circular cooling air ring is arranged above the extrusion die.
- the high-temperature molten resin material is extruded from an extrusion die and cooled by a cooling air ring to form a circular bubble.
- the annular bubble is flattened by a herringbone plate to form a double-layer film. After that, the wind can be wound in the middle of the conventional cooling air ring.
- the air guiding interlayer 3 has a circular shape on the horizontal projection, and the cooling airflow is from the air inlet of the periphery of the circular air guiding interlayer 3. 1
- the radial air passage is directed to the annular air outlet 2 to cool the bubble 8, as shown in Figs.
- the bubble is filled with compressed air, and under the action of compressed air, radial (horizontal) inflation, that is, lateral stretching, thereby making the bubble thin;
- the bubble is directly pulled by the traction nip roller through the vertical direction, and the pulling speed is greater than the extrusion speed, thereby also making the bubble thin, that is, vertical stretching.
- the entire circumference of the bubble is simultaneously thinned in the same proportion, and thus the transverse stretching mechanism and the vertical stretching mechanism are collectively referred to as a full-thickness thickness control mechanism.
- the adjustment of the bubble thickness of the full-thickness thickness control mechanism is global, that is, when the thickness of a certain point in the circumferential direction is increased, other points in the circumferential direction must also be thickened, and vice versa.
- the full-thickness thickness control mechanism cannot perform independent differential adjustment on the circumferential local point thickness, and only equal-scale adjustment can be performed simultaneously for all points.
- FIG. 3 is uniformly arranged with a plurality of electronic control elements 6 in the circumferential direction of the circular wind-guiding interlayer 3 (the number of electronic control elements is generally more than 72, even up to two or three hundred
- the electronic control component can be an electric heating component or an electric valve, and each electronic control component is independently controlled, and the circular air guiding interlayer is evenly divided into a plurality of radial channels 5 from the circumferential direction by using a plurality of partition plates 4, each The electronic control element 6 corresponds to the temperature or flow rate (flow rate) of the air flow of one radial channel 5.
- the cooling airflow passes from the annular air inlet 1 through the radial passages 5 to the annular air outlet 2,
- the temperature of each bubble is controlled to the temperature of each point of the bubble, and the electronic control elements of each radial channel are independently controlled, so that the cooling airflow of the radial channel of the corresponding azimuth is heated or controlled to different degrees to cool the corresponding azimuth.
- the temperature or flow rate of the airflow changes to different degrees, so that the temperature of the point in the corresponding azimuth of the bubble 8 changes to different degrees, so that when the bubble is inflated, the proportion of local point inflation and thinning is different with respect to other parts, so that The degree of inflating and thinning of the local point is different from that of other parts, thereby achieving differentially independent regulation of the thickness of a certain point or points in the circumferential direction.
- the above-described structure for differentially regulating the thickness of some locations in the circumferential direction is called a local thickness control mechanism.
- the local thickness control mechanism can simultaneously perform different ratios of thickness adjustments at different points in the circumferential direction.
- the electronic control component of the local thickness control mechanism changes the operating parameters (for example, reducing the heating power or increasing the opening degree of the valve), when the local thickness control mechanism cools or accelerates the cooling airflow corresponding to the orientation, the bubble point temperature of the corresponding orientation The thickness of the bubble corresponding to the orientation is increased, and this process is called a bubble thickening operation.
- the electronic control component of the local thickness control mechanism changes the operating parameters (for example, increasing the heating power or making the valve opening degree smaller)
- the local thickness control mechanism heats up or decelerates the corresponding cooling airflow
- the bubble point of the corresponding orientation When the temperature rises, the thickness of the bubble corresponding to the orientation becomes smaller, and this process is called a bubble thickening operation.
- the above air velocity can be reduced to zero, that is, the valve is completely closed.
- the operating parameters of the local thickness control mechanism refer to the power of the electric heating element for the mechanism that relies on the electric heating element; the opening size or the opening and closing state of the valve for the mechanism that operates by the valve.
- the actual thickness of each point in the circumferential direction of the bubble must be continuously detected during the production process.
- the prior art can use the thickness measuring probe to continuously rotate around the annular bubble to perform the inspection. The above is responsible for detecting the actual thickness of each point in the circumferential direction of the bubble.
- the device is called a bubble thickness detector.
- the thickness measurement technology is very mature, so the detection result of the bubble thickness detector can be very accurate, the detection accuracy is high, and the detection precision can fully meet the accuracy of the winding quality requirement.
- the control accuracy of the bubble thickness of the full-thickness control mechanism is also high, because the difference in traction speed is directly related to the degree of stretching, and the difference in traction speed can be precisely controlled, so the vertical stretching makes the bubble thinner.
- the ratio can be precisely controlled; for example, if the bubble is required to be thinned by 3%, the positive difference between the traction speed and the extrusion speed can be increased by 3%, and the positive difference between the traction speed and the extrusion speed is increased. After 3%, the thickness of the bubble may not be thinner by 4%, nor may it be thinner by 2%. It can only be accurately reduced by about 3%, so the process from control to reaction is very direct, sensitive, and precise. The correlation between control methods and control results is very high.
- the pressure inside the bubble is directly related to the radial pull.
- the degree of extension and the difference in the pressure inside the bubble can be precisely controlled, and the thickness of the bubble can be precisely controlled by the difference in the pressure inside the bubble.
- the full-thickness thickness control mechanism can accurately control the total thickness of the bubble, and the error of the control result is very small. Compared with the winding quality requirement, the error value can be neglected, so the control of the full-thickness thickness control mechanism can be considered. The result can be accurate to a specific target value.
- the thickness control precision of the local thickness control mechanism of the bubble is relatively low, and can only be roughly controlled. For a specific control action, it can only be predicted according to experience that the control effect will be within a certain interval, and it is difficult to predict what the control result is. Point. This is because the temperature or flow rate of the cooling airflow cannot directly, uniquely and accurately determine the proportion of the local point thickness change of the bubble. It can only be controlled according to experience. Each specific control action can only be roughly predicted before the implementation. result. For example, if the bubble is required to be thinned by 5%, the temperature is not increased by 5%, but the operating parameter (ie, power) of the heating element can only be increased by a value according to experience. After the adjustment, the local point is likely to be changed.
- a thin 3% may also be 7% thinner.
- the value of the local thickness of the bubble cannot be accurately determined. Therefore, although the local thickness control mechanism can control the local thickness of the bubble, the control precision is poor. Compared with the winding quality requirements, the error value can not be ignored, so the control result of the local thickness control mechanism of the bubble can only be predicted. It falls within a certain numerical interval, and it is difficult to expect its control result to be accurate to a specific target value.
- the thickness of the cylindrical bubble extruded from the annular extrusion port of the blow molding device is actually different, for example, corresponding to the orientation of the injection port.
- the thickness of the bubble will be significantly thicker, and the thickness deviation is a systematic error, that is, if the point of a certain direction of the bubble is thick, the subsequent bubble is continuously thick in the direction, so the above conventional method is wound up. If the film is not treated, the thick spots (or bumps) will gradually accumulate at the same position of the coil, so that the thickness of the film roll after winding is severely uneven, resulting in bursting phenomenon and poor winding quality.
- a mechanical rotary traction device was designed to rotate the traction nip roller around the central axis of the machine head, that is, the traction nip roller rotates relative to the blow molding machine die (bubble), so that the film thickness is on the upper axis of the coil.
- the upward distribution position shows the waveform distribution state, along the axial direction of the coil Dispersed, thereby better solving the problem of winding accumulation caused by systematic errors of thick points (or bumps), so that the bumps of the film are evenly distributed in the axial direction of the coil, not in the same Accumulate the position, avoid bursting, and achieve the purpose of winding up.
- Rotating traction devices have appeared in many Chinese patents, such as CN201410774285.4, CN201320366814.8, CN02214546.X, CN200410015430.7, CN200920062191.9 and other Chinese patents.
- the above-mentioned rotary traction device solves the blasting phenomenon well, it pays a great price: the mechanical structure of the rotary traction device is complicated, the equipment is bulky, and when the film runs through the rotary traction mechanism, the surface of the film will be The surface of the movable guide roller is relatively slid and twisted, and the surface of the film may cause sliding friction with the surface of the movable guide roller, and the film is easily accidentally pulled.
- the local thickness control mechanism of the bubble can control the thickness of the local point of the bubble, it cannot be directly used to replace the rotary traction device. This is because of the following two reasons: First, the thickness of the film caused by mechanical reasons Larger, can reach up to 8-11% of the film thickness, and relying on simple temperature adjustment can not reduce the film thickness to 8-11%, because if you increase the temperature, try to use the temperature increase will be 8 If the mechanical error factor of -11% is completely thinned and eliminated, the required temperature rise is too large, which will cause the bubble to not condense at this point. Even under the action of compressed air in the bubble, the bubble will break at this point.
- the object of the present invention is to overcome the above disadvantages and to provide a blown film production process. After the bubble is produced, the accumulated thickness error of each point is uniformly distributed along the axial direction of the coil to avoid the phenomenon of bursting, and the conventional Mechanical rotary traction technology and equipment.
- the blown film device is provided with an extrusion die, the extrusion die is provided with a circular extrusion port, and the extrusion die is provided with a circular ring shape.
- the cooling air ring and the cooling air ring are formed with at least 72 partial thickness control mechanisms, and the respective partial thickness control mechanisms are evenly arranged along the circumferential direction of the cooling air ring; the blown film device is also provided with a full-thickness thickness control mechanism and bubble thickness detection.
- each local thickness control mechanism works with the same working parameters.
- the working parameter is called the original working parameter, and the original working parameter is recorded; the bubble thickness detector continuously detects the bubble circumferential point.
- the initial thickness when the initial thickness of a certain azimuth point in the bubble circumferential direction exceeds the bubble thickness design value a by more than the bubble thickness normal deviation value f, the point at which the bubble is in the orientation is regarded as the original bump,
- the points other than the original bump are regarded as normal points, and the local thickness control mechanism corresponding to the normal point is called the normal point thickness control mechanism;
- the local thickness control mechanism corresponding to the original bump is called the original bump thickness control mechanism;
- the original bump thickness control mechanism starts the bubble thinning operation, changes the working parameters, and reduces the thickness of the original bump of the bubble, and the estimated thickness h of the original bump after the control adjustment is in the following range: a +0.7f>h>a+0.2f;
- the bubble thickness detector continuously detects the thickness of each point of the bubble, and calculates the average value b of the original bump adjustment thickness of each original bump of the bubble after the thickness reduction operation, And record the working parameters of each original bump thickness control mechanism after the thickness reduction operation;
- f is the normal deviation value of the bubble thickness, which can be comprehensively determined according to the requirements of the winding quality level, film thickness, equipment precision and the like;
- the number of normal point thickness control mechanisms for performing the bubble thickening operation in step (3) is gradually increased, or the thickness of the individual normal point thickness control mechanism is gradually increased, and gradually adjusted.
- the high process repeat the average actual thickness of all normal points including the thickening point and calculate the new actual thickness average c, and repeatedly calculate the absolute value d of the new average values c and b, and repeat the comparison.
- the size of d and e up to d ⁇ e and record the number M of normal point thickness control mechanisms for thickening operation in this state, and the operating parameters of the normal point thickness control mechanism for each thickening operation, and then Start step (6);
- the number of normal point thickness control mechanisms for performing the bubble thickening operation in step (3) is gradually lowered, or the thickness of the individual normal point thickness control mechanism is gradually lowered, and gradually adjusted.
- the average actual thickness of all normal points including the thickening point is repeatedly detected and a new average value c is calculated, and the new absolute value d of the new average values c and b is repeatedly calculated, and the comparison is repeated.
- the size of d and e up to d ⁇ e and record the number M of normal point thickness control mechanisms for thickening operation in this state, and the operating parameters of the normal point thickness control mechanism for each thickening operation, and then Start step (6);
- the actual thickness average of each original bump is b
- the actual thickness average of all bubble normal points including the thickening point is also close to b (and b)
- the difference is less than e), that is, the average thickness of the full-circumferential bubble is close to b
- the full-thickness thickness control mechanism lowers the total thickness of the bubble according to the detection result of the bubble thickness detector, so that the total bubble is averaged.
- the thickness becomes smaller as a;
- each original bump thickness control mechanism maintains the operating parameters recorded in step (2); and all normal point thickness control mechanisms alternately select one of them for thickening operation and maintain
- the total number of normal point thickness control mechanisms that perform the thickening operation at each time is the value M recorded in the step (5), and the operating parameters of the normal point thickness control mechanisms of the M thickening operations and the (5)
- the working parameters recorded in the step are the same one-to-one; at each moment, except for the M normal point thickness control mechanisms that perform the thickening operation, the normal point thickness control mechanism that does not perform the thickening operation is still performed with the original working parameters.
- the bubble thickness detector continuously detects the actual thickness of each point in the circumferential direction of the bubble, and the full-thickness thickness control mechanism maintains the average thickness of each point of the entire bubble at a.
- the estimated thickness h of the original bump after the control adjustment is located in the following area
- the range is: a+0.7f>h>a+0.2f,”, this does not mean that a point is selected as the control target in the interval, but the expected thickness h falls within the range, because of this thickness reduction
- the target thickness is a relatively large range of ranges, and the existing local thickness control mechanism can achieve this rough control standard, so there is no difficulty and no special requirements.
- the partial thickness and the cumulative thickness of the film are uniformly distributed along the axial and circumferential directions of the coil to avoid the phenomenon of bursting, and the traditional mechanical rotating traction process can be omitted. And equipment.
- the original bump of the present invention does not have to be excessively heated so that its thickness is completely flattened, thereby avoiding the problem of bubble collapse and bubble collapse.
- the present invention like the conventional process, can only roughly control the thickness of the specific local point of the bubble, it can precisely control the average actual thickness of all the normal points of the bubble (this is because a variation parameter is divided by about 100 samples). After the total number, the degree of influence of the variation parameter on all samples will be reduced by about 100 times than the degree of self-change, which means that the accuracy of the influence of the variation parameter on the average value is two orders of magnitude higher than the accuracy of the self-change, and therefore, the present invention can The average actual thickness of all the normal points of the bubble is accurately equal to the average thickness of each original bump adjusted, thereby making the overall thickness of the film roll uniform.
- the present invention achieves the final bubble by thickening (shaving a part of the thickness of the bump), thickening (slightly thickening the normal point to be substantially equal to the thickness of the sharpened bump), and then thinning the whole.
- the overall average thickness meets the requirements of product quality and does not explode locally.
- the normal point becomes a thickening point, since all normal points are balanced and thickened, there is no accumulation of thickening points and bursting. The problem.
- Fig. 1 is a schematic view showing the structure of a cooling air ring for cooling a bubble.
- FIG. 2 is a schematic diagram showing the horizontal projection position relationship of each main component in FIG. 1.
- FIG. 2 is a schematic diagram showing the horizontal projection position relationship of each main component in FIG. 1.
- Figure 3 is a schematic diagram of the principle of a local thickness control mechanism.
- a blown film production process the blown film equipment is similar to the structure shown in Fig. 1, Fig. 2, Fig. 3, which is provided with an extrusion die, the extrusion die is provided with a circular extrusion port, and an extrusion die
- An annular cooling air ring is arranged above the head, and the air guiding interlayer of the cooling air ring uses a plurality of partition plates to sandwich the circular air guiding layer It is evenly divided into 100 radial channels from the circumferential direction (the number of radial channels in Figure 3 is only schematic, and 100 are not accurately drawn for the sake of simplicity), each radial channel is provided with a local thickness control mechanism.
- the local thickness control mechanism specifically adopts electric heating elements, and each electric heating element is evenly arranged in the circumferential direction, and each electric heating element is located in a radial passage of a cooling air ring; and a full-thickness thickness control mechanism is also provided.
- the bubble thickness detector; the full-thickness thickness control mechanism specifically includes a vertical stretching mechanism led by the traction nip roller and a transverse stretching mechanism led by the air compressor.
- the target value of the bubble thickness is set to 100 ⁇ m, and the conditions for the identification of the original bump are determined according to the characteristics of the mechanical equipment, the production process, and the material: if the bubble thickness in a certain direction is greater than the bubble
- the thickness target value is 100 micrometers and exceeds 10 micrometers (10 micrometers is the normal deviation value f of the bubble thickness, the value f is comprehensively determined according to the requirements of the winding quality grade, film thickness, equipment accuracy, etc., and is set in advance)
- the original bump caused by the mechanical problem is determined by the orientation, and the other azimuth points other than the original bump are regarded as normal points.
- the maximum allowable difference e is determined to be 1.5 microns, where e is the maximum allowable difference between c and b, and c is the thickening point.
- the actual thickness average of all bubble normal points, b is the average value of the original bump adjustment thickness after adjustment of each original bump of the bubble.
- the practical significance of the maximum allowable difference e is that as long as the average thickness of the final thickness of all the bubble normal points does not differ from the average thickness of the original bump adjustment by e (1.5 micrometers), it is considered to meet the requirements of the winding quality. .
- the process comprises the following steps: (1), the annular extrusion port of the extrusion die continuously extrude the annular film blank, and after the film blank is extruded, the inflating and the cooling air ring are cooled to form a bubble, and the film begins.
- the heating elements of the cooling air ring are all operated at the same heating power, the heating power is the original working parameter, and the original working parameters are recorded;
- the bubble thickness detector continuously detects the initial thickness of each point in the circumferential direction of the bubble, and the initial thickness of a certain azimuth point in the bubble circumferential direction reaches 110 ⁇ m or more (above the target value of 100 ⁇ m of the bubble thickness exceeds the set value of 10 ⁇ m or more,
- 10 micron is the normal deviation value f
- the point at which the bubble is in the azimuth is regarded as the original bump
- the other azimuth points other than the original bump are regarded as the normal point
- the local thickness control mechanism corresponding to the orientation of the normal point It is called a normal point thickness control mechanism
- the local thickness control mechanism of the original bump corresponding orientation is called the original bump thickness control mechanism;
- each original bump thickness control machine component starts the bubble thinning operation, that is, the original
- the electric heating element corresponding to the azimuth of the bump increases the electric heating power, increases the bubble temperature at the original bump, and reduces the thickness of the original bump of the bubble, and the estimated thickness h of the original bump after the control adjustment is in the following range: a+ 0.7f>h>a+0.2f, that is, the estimated thickness h of the original bump after the control adjustment is less than 107 ⁇ m and larger than 102 ⁇ m;
- the bubble thickness detector continuously detects the actual thickness of each point of the bubble, and calculates each bubble.
- the original bump adjusted original bump adjusts the average value b of the thickness, and records the working parameters of each original bump thickness control mechanism after the thickness reduction operation, that is, records the original bump thickness control mechanism after performing the thickness reduction operation Electric heating power of the electric heating element;
- the normal point thickness control mechanism In all the normal point thickness control mechanisms, a part of the normal point thickness control mechanism is selected for the bubble thickening operation, and the way of the bubble thickening operation is to reduce the electric heating power of the corresponding electric heating element, so that the corresponding orientation
- the local temperature of the bubble decreases, and the normal point of the normal thickness control mechanism selected for the thickening operation is called the thickening point (the thickening point is still understood to be a component of the normal point);
- the bubble thickness detector Continue to continuously detect the actual thickness of each point of the bubble, calculate the average actual thickness c of all the normal points of the bubble including the thickening point; the normal point thickness control mechanism that is not selected for the bubble thickening operation still maintains the original work parameter;
- the thickening operation is achieved. Recording the number M of the normal point thickness control mechanisms for performing the thickening operation in this state, and the operating parameters (electrical heating power) of the normal thickness control mechanism (electric heating element) for each thickening operation, and starting the sixth (6) )step;
- the number of normal point thickness control mechanisms for performing the bubble thickening operation in step (3) is gradually increased, and the number of normal point thickness control mechanisms for each bubble thickening operation is adjusted. Higher one, although it is not possible to accurately predict the increase in bubble thickness corresponding to the local normal point A few microns, but it is expected that the average actual thickness of all normal points (100 points) including the thickening point will increase by less than 0.1 micron. This control accuracy is far beyond the need to gradually increase the bubble.
- the average actual thickness of all normal points including the thickening point is repeatedly detected and a new average value c is calculated, and the new average values c and b are repeatedly calculated.
- the new absolute value of the difference d repeatedly compares the size of d and e; until d ⁇ e, when d ⁇ e, means that the average actual thickness of all normal points of the bubble and the average actual thickness of the original bump are not more than 1.5 Micron, enters the range of tolerance that can be tolerated, therefore, indicates that the thickening operation achieves the purpose, records the number M of the normal point thickness control mechanism for thickening operation in this state, and the normal point thickness control for each thickening operation Operating parameters (electrical heating power) of the mechanism (electric heating element), and then starting step (6);
- the number of normal point thickness control mechanisms for performing the bubble thickening operation in step (3) is gradually lowered, and the number of normal point thickness control mechanisms for performing the bubble thickening operation is lowered.
- One restores the normal point thickness control mechanism for one of the bubble thickening operations to the original operating parameters
- the average actual thickness of all normal points (100 points) within the range will be reduced by less than 0.1 micron. This control accuracy is far beyond the need to gradually reduce the number of normal thickness control mechanisms for bubble thickening operations.
- the actual thickness average of each original bump is b, and the average actual thickness c of all bubble normal points including the thickening point is also close to b, after which,
- the circumferential thickness control mechanism lowers the total thickness of the bubble according to the detection result of the bubble thickness detector, specifically, increases the bubble pulling speed, so that the average thickness of the whole cell bubble becomes smaller a;
- the local thickness control mechanism (electric heating element) corresponding to the orientation of each original bump maintains the operating parameter (electrical heating power) recorded in the step (2), And all the normal point thickness control mechanisms alternately select one of them to perform the bubble thickening operation, and maintain the normal point thickness control mechanism at each moment for the thickening operation, which is the M records recorded in the step (5), And the heating power of the electric heating elements of the M normal thickness control mechanisms for performing the thickening operation is the same as the heating power recorded in the step (5); at each moment, except for the M normal point thicknesses for performing the thickening operation In addition to the control mechanism, the remaining normal thickness control mechanism that does not perform the thickening operation still works with the original working parameters; the bubble thickness detector continuously detects the actual thickness of each point in the bubble circumferential direction, and the full-thickness thickness control mechanism (specifically The vertical stretching mechanism maintains the average thickness of each point of the entire circumference of the bubble to 100 microns, after which the bubble can be wound directly without mechanically
- step (2) "the estimated thickness h of the original bump after the control adjustment is less than 107 micrometers and larger than 102 micrometers", since the target thickness after the thickness reduction is a relatively large interval range, the existing partial thickness control mechanism This rough control standard can be achieved, so there is no difficulty and no special requirements.
- the full-thickness thickness control mechanism may also adopt a transverse stretching mechanism dominated by the air compressor, and the bubble pressure is used to control the total thickness of the bubble.
- the partial thickness control mechanism can also adopt an electric valve installed in the radial passage, and the working parameter is the valve opening size or the valve switching state, and the thickening operation mode is to increase the valve opening degree, and the thickness is reduced.
- the mode of operation is to reduce the degree of valve opening.
- the value of the local thickness control mechanism can be changed to 72, or can be changed to 144, or 288, or 360, and the like.
- the sub-step of "gradually lowering the number of the normal point thickness control means for performing the bubble thickening operation" may also gradually reduce the bubble increase of a part of the thickening point.
- the magnitude of the thick operation such as gradually increasing the power of a portion of the thickened electric heating element, results in a fine reduction in the "average actual thickness of all normal points including the thickening point".
- the sub-step of "gradually increasing the number of normal point thickness control mechanisms for performing the bubble thickening operation” may also be carried out by gradually increasing the bubble growth of a part of the thickening points.
- the magnitude of the thick operation such as the electric heating element that gradually reduces a part of the thickening point
- the power of the piece the result also allows the "average actual thickness of all normal points including the thickening point" to be finely increased.
- the target value a of the bubble thickness, the normal deviation value f of the bubble thickness, and the maximum allowable difference e may be specifically determined according to the actual winding volume and quality requirements, and the values of these values are mainly based on The product quality requirements are flexible and determined, and are not the problems to be solved by the present invention.
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Abstract
A film blowing production process comprises the following steps: (1) a bubble thickness measuring device continuously measures initial thicknesses of various points on a bubble along a circumferential direction; (2) various initial bump thickness control mechanisms start to perform a bubble thickness reducing operation; (3) select some from all normal point thickness control mechanisms for performing a bubble thickening operation; (4) calculate an absolute value d of the difference between c and b, i.e., d = |c - b|, wherein c is an average value of actual thicknesses of all the normal points of the bubble, including the thickened ones, after the thickening operation, and b is an average value of the adjusted initial bump thicknesses of the various initial bumps of the bubble after the thickness reducing operation; (5) compare d with e, wherein e is the maximum allowable difference between c and b, and proceed to step (6); and (6) a full-circumference thickness control mechanism reduces the full-circumference thickness of the bubble according to the measurement result of the bubble thickness measuring device, to reduce the average full-circumference thickness of the bubble to a, wherein a is a designed value for the thickness of the bubble. After the produced bubble is rolled, the accumulative error of thicknesses of various points is evenly distributed along an axial direction of the roll, thereby avoiding winder wrinkles, and a traditional mechanical rotational traction process and apparatus are also omitted.
Description
本发明属于塑料膜生产工艺的技术领域,具体涉及一种吹膜生产工艺。The invention belongs to the technical field of plastic film production processes, and in particular relates to a blown film production process.
塑料膜可以由吹膜设备采用吹膜工艺生产,吹膜设备设有挤出模头,挤出模头设有圆环形挤出口,挤出模头上方设有圆环形的冷却风环,生产时,高温熔融的树脂物料由挤出模头挤出后,经过冷却风环的冷却而形成圆环形的膜泡,圆环形的膜泡经过人字板压扁后成为双层薄膜,此后可收卷;常规的冷却风环的中间都设有导风夹层3,导风夹层3在水平投影上的形状呈圆环形,冷却气流从圆环形导风夹层3外围的的进风口1经过径向通道流向达到圆环形的出风口2,从而对膜泡8实施冷却,如图1、图2所示。The plastic film can be produced by a blown film device using a blown film process, the blown film device is provided with an extrusion die, the extrusion die is provided with a circular extrusion port, and a circular cooling air ring is arranged above the extrusion die. During production, the high-temperature molten resin material is extruded from an extrusion die and cooled by a cooling air ring to form a circular bubble. The annular bubble is flattened by a herringbone plate to form a double-layer film. After that, the wind can be wound in the middle of the conventional cooling air ring. The air guiding interlayer 3 has a circular shape on the horizontal projection, and the cooling airflow is from the air inlet of the periphery of the circular air guiding interlayer 3. 1 The radial air passage is directed to the annular air outlet 2 to cool the bubble 8, as shown in Figs.
在上述过程中,膜泡中充入有压缩空气,膜泡在压缩空气作用下,会发生径向(水平方向)吹胀,即横向拉伸,由此可使膜泡变薄;另一方面,膜泡直接由牵引夹辊经过竖向快速牵引,牵引速度大于挤出速度,由此也可使膜泡变薄,即竖向拉伸。上述横向拉伸和竖向拉伸过程中,膜泡全周各点都同时同比例地变薄,因此横向拉伸机构和竖向拉伸机构统称为全周厚度控制机构。全周厚度控制机构的膜泡厚度调节是全局性的,即当周向上的某一点厚度调大时,周向上的其它点必定也随之增厚,反之亦然。全周厚度控制机构不能对周向的局部点厚度实施独立地差异化调节,只能对所有点同时实施等比例调节。In the above process, the bubble is filled with compressed air, and under the action of compressed air, radial (horizontal) inflation, that is, lateral stretching, thereby making the bubble thin; The bubble is directly pulled by the traction nip roller through the vertical direction, and the pulling speed is greater than the extrusion speed, thereby also making the bubble thin, that is, vertical stretching. In the above-mentioned transverse stretching and vertical stretching processes, the entire circumference of the bubble is simultaneously thinned in the same proportion, and thus the transverse stretching mechanism and the vertical stretching mechanism are collectively referred to as a full-thickness thickness control mechanism. The adjustment of the bubble thickness of the full-thickness thickness control mechanism is global, that is, when the thickness of a certain point in the circumferential direction is increased, other points in the circumferential direction must also be thickened, and vice versa. The full-thickness thickness control mechanism cannot perform independent differential adjustment on the circumferential local point thickness, and only equal-scale adjustment can be performed simultaneously for all points.
后来,人们设计了能对膜泡周向局部位置的厚度进行调节的结构。其中一种结构如图3所示,该结构在圆环形导风夹层3的周向上均匀布置有多个电控元件6(电控元件的数量一般多于72个,甚至可达两三百个),电控元件可以为电热元件或电动阀门,各个电控元件独立控制,并利用多片分隔板4将圆环形导风夹层从周向上均匀分隔为多个径向通道5,每个电控元件6对应控制一个径向通道5的气流温度或流量(流速)。工作时,冷却气流从圆环形的进风口1经过各径向通道5达到圆环形的出风口2,
对膜泡8周向各点温度实施控制,而且各径向通道的电控元件分别独立控制,从而将相应方位的径向通道的冷却气流进行不同程度的加热或控制流量,使相应方位的冷却气流的温度或流速发生不同程度的改变,进而使膜泡8相应方位上的点温度不同程度的改变,于是膜泡吹胀时,局部点吹胀变薄的比例相对于其它部位发生差异,使该局部点吹胀变薄的程度相对于其它部位发生差异,由此实现对周向局部某个点或某些点的厚度进行差异化地独立调控。上述对周向局部某些位置的厚度进行差异化调控的结构称为局部厚度控制机构。局部厚度控制机构能对周向上的不同点同时实施不同比例地厚度调节。当局部厚度控制机构的电控元件改变工作参数(例如降低加热功率或将阀门开口度变大一些),使该局部厚度控制机构对应方位的冷却气流降温或加速时,对应方位的膜泡点温度降低,对应方位的膜泡厚度变大,此种过程称为膜泡增厚操作。当局部厚度控制机构的电控元件改变工作参数(例如加大加热功率或将阀门开口度变小一些),使该局部厚度控制机构对应方位的冷却气流升温或减速时,对应方位的膜泡点温度升高,对应方位的膜泡厚度变小,此种过程称为膜泡减厚操作。上述气流速度可以减为零,即阀门完全关闭。所谓局部厚度控制机构的工作参数,对于依靠电热元件工作的机构而言,是指电热元件的功率;对于依靠阀门工作的机构而言,是指阀门的开口大小或开闭状态。Later, a structure was designed which can adjust the thickness of the circumferential local position of the bubble. One of the structures is shown in FIG. 3, which is uniformly arranged with a plurality of electronic control elements 6 in the circumferential direction of the circular wind-guiding interlayer 3 (the number of electronic control elements is generally more than 72, even up to two or three hundred The electronic control component can be an electric heating component or an electric valve, and each electronic control component is independently controlled, and the circular air guiding interlayer is evenly divided into a plurality of radial channels 5 from the circumferential direction by using a plurality of partition plates 4, each The electronic control element 6 corresponds to the temperature or flow rate (flow rate) of the air flow of one radial channel 5. During operation, the cooling airflow passes from the annular air inlet 1 through the radial passages 5 to the annular air outlet 2,
The temperature of each bubble is controlled to the temperature of each point of the bubble, and the electronic control elements of each radial channel are independently controlled, so that the cooling airflow of the radial channel of the corresponding azimuth is heated or controlled to different degrees to cool the corresponding azimuth. The temperature or flow rate of the airflow changes to different degrees, so that the temperature of the point in the corresponding azimuth of the bubble 8 changes to different degrees, so that when the bubble is inflated, the proportion of local point inflation and thinning is different with respect to other parts, so that The degree of inflating and thinning of the local point is different from that of other parts, thereby achieving differentially independent regulation of the thickness of a certain point or points in the circumferential direction. The above-described structure for differentially regulating the thickness of some locations in the circumferential direction is called a local thickness control mechanism. The local thickness control mechanism can simultaneously perform different ratios of thickness adjustments at different points in the circumferential direction. When the electronic control component of the local thickness control mechanism changes the operating parameters (for example, reducing the heating power or increasing the opening degree of the valve), when the local thickness control mechanism cools or accelerates the cooling airflow corresponding to the orientation, the bubble point temperature of the corresponding orientation The thickness of the bubble corresponding to the orientation is increased, and this process is called a bubble thickening operation. When the electronic control component of the local thickness control mechanism changes the operating parameters (for example, increasing the heating power or making the valve opening degree smaller), when the local thickness control mechanism heats up or decelerates the corresponding cooling airflow, the bubble point of the corresponding orientation When the temperature rises, the thickness of the bubble corresponding to the orientation becomes smaller, and this process is called a bubble thickening operation. The above air velocity can be reduced to zero, that is, the valve is completely closed. The operating parameters of the local thickness control mechanism refer to the power of the electric heating element for the mechanism that relies on the electric heating element; the opening size or the opening and closing state of the valve for the mechanism that operates by the valve.
另外,在生产过程中必须不断检测膜泡周向各点的实际厚度,现有技术可以使用测厚探头围绕着环形膜泡不断转动进行巡回检测,上述负责检测膜泡周向各点的实际厚度的装置称为膜泡厚度检测器。In addition, the actual thickness of each point in the circumferential direction of the bubble must be continuously detected during the production process. The prior art can use the thickness measuring probe to continuously rotate around the annular bubble to perform the inspection. The above is responsible for detecting the actual thickness of each point in the circumferential direction of the bubble. The device is called a bubble thickness detector.
上述膜泡厚度检测器、局部厚度控制机构、全周厚度控制机构三者的精确度情况分别如下:The accuracy of the above bubble thickness detector, local thickness control mechanism, and full-thickness thickness control mechanism are as follows:
测厚技术已经非常成熟,因而膜泡厚度检测器的检测结果可以非常精准,检测精确度很高,检测精度完全能够满足收卷质量要求的精度。The thickness measurement technology is very mature, so the detection result of the bubble thickness detector can be very accurate, the detection accuracy is high, and the detection precision can fully meet the accuracy of the winding quality requirement.
全周厚度控制机构的对膜泡厚度的控制精度也很高,这是因为,由于牵引速度差直接关系到拉伸程度,且牵引速度差可以精确控制,因此竖向拉伸使膜泡变薄的比例可精确地控制;例如,假如需要将膜泡变薄3%,则只要使牵引速度与挤出速度的正差值增加3%即可,当牵引速度与挤出速度的正差值增加3%后,膜泡的厚度不可能变薄4%,也不可能变薄2%,
只能精确在变薄3%左右,因此从控制手段到产生反应的过程非常直接、灵敏、精准,控制手段与控制结果的相关度非常高;同样,由于泡内气压大小直接关系到径向拉伸程度,且泡内气压大小差可以精确控制,利用泡内气压大小差也可以精确控制膜泡的厚度。总之,全周厚度控制机构可精确地控制膜泡全周厚度,其控制结果的误差非常小,相对于收卷质量要求来说,误差值可以忽略不计,因而可以认为全周厚度控制机构的控制结果能够精确到某个具体的目标值。The control accuracy of the bubble thickness of the full-thickness control mechanism is also high, because the difference in traction speed is directly related to the degree of stretching, and the difference in traction speed can be precisely controlled, so the vertical stretching makes the bubble thinner. The ratio can be precisely controlled; for example, if the bubble is required to be thinned by 3%, the positive difference between the traction speed and the extrusion speed can be increased by 3%, and the positive difference between the traction speed and the extrusion speed is increased. After 3%, the thickness of the bubble may not be thinner by 4%, nor may it be thinner by 2%.
It can only be accurately reduced by about 3%, so the process from control to reaction is very direct, sensitive, and precise. The correlation between control methods and control results is very high. Similarly, the pressure inside the bubble is directly related to the radial pull. The degree of extension and the difference in the pressure inside the bubble can be precisely controlled, and the thickness of the bubble can be precisely controlled by the difference in the pressure inside the bubble. In short, the full-thickness thickness control mechanism can accurately control the total thickness of the bubble, and the error of the control result is very small. Compared with the winding quality requirement, the error value can be neglected, so the control of the full-thickness thickness control mechanism can be considered. The result can be accurate to a specific target value.
而膜泡局部厚度控制机构的厚度控制精度则较低,只能粗略地控制,对于具体一次调控动作,只能根据经验预计其控制效果会在某个区间内,而难以预计到控制结果到什么点位。这是因为,冷却气流的温度或流量并不能直接、唯一、精确地决定膜泡局部点厚度改变比例,只能根据经验大致进行控制,每次具体的控制动作在实施之前,只能大致预计控制结果。例如,假如需要将膜泡变薄5%,并不是将温度提升5%,而只能根据经验将电热元件的工作参数(即功率)调大一个数值,在调节后,局部点很可能是变薄3%,也可能是变薄7%,。同理,依据阀门的工作参数(即阀门开口大小)也无法精确确定膜泡局部厚度的数值。因此说,局部厚度控制机构虽可控制膜泡局部厚度,但控制精度较差,相对于收卷质量要求来说,其误差值不能忽略不计,因而膜泡局部厚度控制机构的控制结果只能预计其落在某一个数值区间,而难以期望其控制结果精确到某个具体的目标值。The thickness control precision of the local thickness control mechanism of the bubble is relatively low, and can only be roughly controlled. For a specific control action, it can only be predicted according to experience that the control effect will be within a certain interval, and it is difficult to predict what the control result is. Point. This is because the temperature or flow rate of the cooling airflow cannot directly, uniquely and accurately determine the proportion of the local point thickness change of the bubble. It can only be controlled according to experience. Each specific control action can only be roughly predicted before the implementation. result. For example, if the bubble is required to be thinned by 5%, the temperature is not increased by 5%, but the operating parameter (ie, power) of the heating element can only be increased by a value according to experience. After the adjustment, the local point is likely to be changed. A thin 3% may also be 7% thinner. Similarly, depending on the operating parameters of the valve (ie, the size of the valve opening), the value of the local thickness of the bubble cannot be accurately determined. Therefore, although the local thickness control mechanism can control the local thickness of the bubble, the control precision is poor. Compared with the winding quality requirements, the error value can not be ignored, so the control result of the local thickness control mechanism of the bubble can only be predicted. It falls within a certain numerical interval, and it is difficult to expect its control result to be accurate to a specific target value.
另一方面,由于机械设计、机械结构、机械加工等原因,从吹塑设备的圆环形挤出口挤出的圆筒状膜泡各点厚薄其实具有差异,例如在射料口对应方位的的膜泡厚度会明显偏厚,而且这种厚度偏差属于系统性误差,即如果膜泡某一方位的点偏厚,则后续出来的膜泡在该方位持续偏厚,所以上述传统方式收卷后的薄膜,如果不加处理,厚点(或称凸点)会在卷材的相同位置逐渐累计叠加,使收卷后的膜卷厚度严重不均匀,产生爆筋现象,收卷质量差。On the other hand, due to mechanical design, mechanical structure, mechanical processing, etc., the thickness of the cylindrical bubble extruded from the annular extrusion port of the blow molding device is actually different, for example, corresponding to the orientation of the injection port. The thickness of the bubble will be significantly thicker, and the thickness deviation is a systematic error, that is, if the point of a certain direction of the bubble is thick, the subsequent bubble is continuously thick in the direction, so the above conventional method is wound up. If the film is not treated, the thick spots (or bumps) will gradually accumulate at the same position of the coil, so that the thickness of the film roll after winding is severely uneven, resulting in bursting phenomenon and poor winding quality.
为了克服上述缺点,人们设计了机械旋转牵引装置,使牵引夹辊绕机头中心轴线旋转,即牵引夹辊相对于吹塑机模头(膜泡)旋转,这样薄膜厚点在卷材上轴向上的分布位置便呈现出波形分布状态,沿卷材的轴向分
散开来,由此较好地解决了厚点(或称凸点)系统性误差而带来的收卷累积问题,使薄膜的凸点在卷材的轴向上均匀分布,不会在同一位置累积,避免爆筋,达到收卷平整的目的。旋转牵引装置在诸多中国专利有出现,例如CN201410774285.4、CN201320366814.8、CN02214546.X、CN200410015430.7、CN200920062191.9等中国专利。In order to overcome the above shortcomings, a mechanical rotary traction device was designed to rotate the traction nip roller around the central axis of the machine head, that is, the traction nip roller rotates relative to the blow molding machine die (bubble), so that the film thickness is on the upper axis of the coil. The upward distribution position shows the waveform distribution state, along the axial direction of the coil
Dispersed, thereby better solving the problem of winding accumulation caused by systematic errors of thick points (or bumps), so that the bumps of the film are evenly distributed in the axial direction of the coil, not in the same Accumulate the position, avoid bursting, and achieve the purpose of winding up. Rotating traction devices have appeared in many Chinese patents, such as CN201410774285.4, CN201320366814.8, CN02214546.X, CN200410015430.7, CN200920062191.9 and other Chinese patents.
然而,上述旋转牵引装置虽然很好地解决了爆筋现象,但却付出很大的代价:旋转牵引装置的机械结构复杂,设备体积大,而且薄膜运行经过旋转牵引机构时,薄膜表面会与各活动导辊表面产生相对滑动、扭动,薄膜表面会与活动导辊表面产生滑动摩擦,薄膜容易被意外拉伤。However, although the above-mentioned rotary traction device solves the blasting phenomenon well, it pays a great price: the mechanical structure of the rotary traction device is complicated, the equipment is bulky, and when the film runs through the rotary traction mechanism, the surface of the film will be The surface of the movable guide roller is relatively slid and twisted, and the surface of the film may cause sliding friction with the surface of the movable guide roller, and the film is easily accidentally pulled.
与此同时,虽然膜泡局部厚度控制机构能够控制膜泡局部点的厚度,但仍不能简单直接用以代替旋转牵引装置,这是因为以下两方面原因:一、机械原因产生的薄膜偏厚幅度较大,最多可以达到膜厚的8-11%左右,而依靠单纯温度调节不可能使薄膜厚度偏厚幅度调低到8-11%,因为如果一味升高温度,企图利用温度升高将8-11%的机械误差因素完全削薄消除,则需要的升温幅度太大,这会导致膜泡在该点不能凝结,甚至在泡内压缩空气的作用下,膜泡会在该点破裂而使泡内气压丧失,进而导致膜泡坍塌的的严重问题;二、如前所述,即使机械原因产生的凸点超厚幅度在局部厚度控制机构的控制能力范围之内,但也由于膜泡局部厚度控制机构的控制精度非常低,因此不管如何控制,单纯依靠膜泡局部厚度控制机构很难将凸点精确消除而避免爆筋现象。At the same time, although the local thickness control mechanism of the bubble can control the thickness of the local point of the bubble, it cannot be directly used to replace the rotary traction device. This is because of the following two reasons: First, the thickness of the film caused by mechanical reasons Larger, can reach up to 8-11% of the film thickness, and relying on simple temperature adjustment can not reduce the film thickness to 8-11%, because if you increase the temperature, try to use the temperature increase will be 8 If the mechanical error factor of -11% is completely thinned and eliminated, the required temperature rise is too large, which will cause the bubble to not condense at this point. Even under the action of compressed air in the bubble, the bubble will break at this point. Loss of air pressure in the bubble, which in turn leads to serious problems of bubble collapse; Second, as mentioned above, even if the super-thickness of the bump generated by mechanical reasons is within the control ability of the local thickness control mechanism, it is also due to the local bubble The control precision of the thickness control mechanism is very low, so no matter how it is controlled, it is difficult to accurately eliminate the bumps and avoid the ribbing phenomenon simply by relying on the local thickness control mechanism of the bubble.
发明内容Summary of the invention
本发明的目的在于克服上述缺点而提供一种吹膜生产工艺,它生产的膜泡收卷后,各点厚度累积误差沿卷材轴向呈均匀分布,避免爆筋现象,且可省略传统的机械旋转牵引工艺和设备。The object of the present invention is to overcome the above disadvantages and to provide a blown film production process. After the bubble is produced, the accumulated thickness error of each point is uniformly distributed along the axial direction of the coil to avoid the phenomenon of bursting, and the conventional Mechanical rotary traction technology and equipment.
其目的可以按以下方案实现:一种吹膜生产工艺,采用的吹膜设备设有挤出模头,挤出模头设有圆环形挤出口,挤出模头上方设有圆环形的冷却风环,冷却风环形成有至少72个局部厚度控制机构,各个局部厚度控制机构沿冷却风环的周向均匀布置;采用的吹膜设备还设有全周厚度控制机构、膜泡厚度检测器;包括以下步骤:The purpose can be achieved according to the following scheme: a blown film production process, the blown film device is provided with an extrusion die, the extrusion die is provided with a circular extrusion port, and the extrusion die is provided with a circular ring shape. The cooling air ring and the cooling air ring are formed with at least 72 partial thickness control mechanisms, and the respective partial thickness control mechanisms are evenly arranged along the circumferential direction of the cooling air ring; the blown film device is also provided with a full-thickness thickness control mechanism and bubble thickness detection. The following steps are included:
(1)、挤出模头的圆环形挤出口不断挤出圆环状的膜坯,膜坯挤出后经
过吹胀和冷却而形成膜泡,各局部厚度控制机构均以相同工作参数工作,该工作参数称为原始工作参数,记录该原始工作参数;膜泡厚度检测器不断检测膜泡周向上各点的初始厚度;当膜泡周向上某个方位点的初始厚度比膜泡厚度设计值a超出的数值大于膜泡厚度正常偏差值f时,将膜泡在该方位的点认定为原始凸点,原始凸点以外其它方位的点认定为正常点,正常点对应方位的局部厚度控制机构称为正常点厚度控制机构;原始凸点对应方位的局部厚度控制机构称为原始凸点厚度控制机构;(1) The annular extrusion port of the extrusion die continuously extrude the annular film blank, and the film blank is extruded
After inflating and cooling to form a bubble, each local thickness control mechanism works with the same working parameters. The working parameter is called the original working parameter, and the original working parameter is recorded; the bubble thickness detector continuously detects the bubble circumferential point. The initial thickness; when the initial thickness of a certain azimuth point in the bubble circumferential direction exceeds the bubble thickness design value a by more than the bubble thickness normal deviation value f, the point at which the bubble is in the orientation is regarded as the original bump, The points other than the original bump are regarded as normal points, and the local thickness control mechanism corresponding to the normal point is called the normal point thickness control mechanism; the local thickness control mechanism corresponding to the original bump is called the original bump thickness control mechanism;
(2)、各原始凸点厚度控制机构开始进行膜泡减厚操作,改变工作参数,使膜泡原始凸点的厚度降低,且控制调整后原始凸点的预计厚度h位于以下区间范围:a+0.7f>h>a+0.2f;膜泡厚度检测器继续不断检测膜泡各点的厚度,计算出膜泡各原始凸点在减厚操作后的原始凸点调整厚度的平均值b,并记录进行减厚操作后的各原始凸点厚度控制机构的工作参数;f为膜泡厚度正常偏差值,可根据收卷质量等级要求、薄膜厚度、设备精度等因素综合决定、事先设定;(2) The original bump thickness control mechanism starts the bubble thinning operation, changes the working parameters, and reduces the thickness of the original bump of the bubble, and the estimated thickness h of the original bump after the control adjustment is in the following range: a +0.7f>h>a+0.2f; the bubble thickness detector continuously detects the thickness of each point of the bubble, and calculates the average value b of the original bump adjustment thickness of each original bump of the bubble after the thickness reduction operation, And record the working parameters of each original bump thickness control mechanism after the thickness reduction operation; f is the normal deviation value of the bubble thickness, which can be comprehensively determined according to the requirements of the winding quality level, film thickness, equipment precision and the like;
(3)、在所有正常点厚度控制机构中,选取其中一部分正常点厚度控制机构进行膜泡增厚操作,改变工作参数,被选中进行增厚操作的正常点厚度控制机构对应方位的膜泡正常点称为增厚点;膜泡厚度检测器继续不断检测膜泡各点的厚度,计算出包括增厚点在内的所有膜泡正常点在增厚操作后的平均实际厚度c;不被选中进行膜泡增厚操作的正常点厚度控制机构仍然保持原始工作参数;(3) In all the normal point thickness control mechanisms, select some of the normal point thickness control mechanisms to perform the bubble thickening operation, change the working parameters, and the normal point thickness control mechanism selected for the thickening operation is normal. The point is called the thickening point; the bubble thickness detector continues to continuously detect the thickness of each point of the bubble, and calculates the average actual thickness c of all the normal points of the bubble including the thickening point after the thickening operation; The normal point thickness control mechanism for performing the bubble thickening operation still maintains the original operating parameters;
(4)、计算c和b两者的差值绝对值d,其中c为包括增厚点在内的所有膜泡正常点在增厚操作后的实际厚度平均值,b为膜泡各原始凸点在减厚操作后的原始凸点调整厚度的平均值,d=|c-b|;(4) Calculate the absolute value d of the difference between c and b, where c is the actual thickness average of all bubble normal points including the thickening point after the thickening operation, and b is the original convex of the bubble The average value of the original bump adjustment thickness after the thickness reduction operation, d=|cb|;
(5)、比较d和e的大小,其中e为c和b两者的最大允许差值;e根据收卷质量等级要求、薄膜厚度、设备精度等因素综合决定、事先设定,一般情况下e可以在0.1f至0.25f之间选择;如果d≤e,则说明所有膜泡正常点在调整后的平均实际厚度与原始凸点在调整后的平均实际厚度两者差值属于可以承受的偏差范围,记录在此种状态下进行增厚操作的正常点厚度控制机构的数量M,以及每个进行增厚操作的正常点厚度控制机构的工作参数,并开始第(6)步骤;
(5), compare the size of d and e, where e is the maximum allowable difference between c and b; e is determined according to the quality requirements of the winding quality, film thickness, equipment accuracy and other factors, in advance, under normal circumstances e can be selected between 0.1f and 0.25f; if d≤e, it means that the difference between the average actual thickness of all the normal points of the bubble and the average actual thickness of the original bump after adjustment is affordable. The range of deviation, the number M of the normal point thickness control mechanisms for performing the thickening operation in this state, and the operating parameters of the normal point thickness control mechanism for each thickening operation, and starting the step (6);
如果d>e,则进一步比较c和b两者大小;If d>e, further compare the size of both c and b;
如果c<b,则将步骤(3)中进行膜泡增厚操作的正常点厚度控制机构的数量逐步调高,或将其中个别正常点厚度控制机构的增厚程度逐步调高,在逐步调高过程中,重复检测包括增厚点在内的所有正常点的平均实际厚度并计算出新的实际厚度平均值c,重复计算新的平均值c和b两者差值绝对值d,重复比较d和e的大小,直至d≤e,并记录在此种状态下进行增厚操作的正常点厚度控制机构的数量M,以及每个进行增厚操作的正常点厚度控制机构的工作参数,然后开始第(6)步骤;If c<b, the number of normal point thickness control mechanisms for performing the bubble thickening operation in step (3) is gradually increased, or the thickness of the individual normal point thickness control mechanism is gradually increased, and gradually adjusted. In the high process, repeat the average actual thickness of all normal points including the thickening point and calculate the new actual thickness average c, and repeatedly calculate the absolute value d of the new average values c and b, and repeat the comparison. The size of d and e up to d ≤ e, and record the number M of normal point thickness control mechanisms for thickening operation in this state, and the operating parameters of the normal point thickness control mechanism for each thickening operation, and then Start step (6);
如果c>b,则将步骤(3)中进行膜泡增厚操作的正常点厚度控制机构的数量逐步调低,或逐步将其中个别正常点厚度控制机构的增厚幅度调低,在逐步调低过程中,重复检测包括增厚点在内的所有正常点的平均实际厚度并计算出新的平均值c,重复计算新的平均值c和b两者新的差值绝对值d,重复比较d和e的大小,直至d≤e,并记录在此种状态下进行增厚操作的正常点厚度控制机构的数量M,以及每个进行增厚操作的正常点厚度控制机构的工作参数,然后开始第(6)步骤;If c>b, the number of normal point thickness control mechanisms for performing the bubble thickening operation in step (3) is gradually lowered, or the thickness of the individual normal point thickness control mechanism is gradually lowered, and gradually adjusted. In the low process, the average actual thickness of all normal points including the thickening point is repeatedly detected and a new average value c is calculated, and the new absolute value d of the new average values c and b is repeatedly calculated, and the comparison is repeated. The size of d and e up to d ≤ e, and record the number M of normal point thickness control mechanisms for thickening operation in this state, and the operating parameters of the normal point thickness control mechanism for each thickening operation, and then Start step (6);
(6)、在上述步骤(5)完成后,各原始凸点的实际厚度平均值为b,包括增厚点在内的所有膜泡正常点的实际厚度平均值也接近于b(与b的差值小于e),即全周膜泡的实际厚度平均值接近于b,全全周厚度控制机构根据膜泡厚度检测器的检测结果而调低膜泡全周厚度,使全周膜泡平均厚度变小为a;(6) After the completion of the above step (5), the actual thickness average of each original bump is b, and the actual thickness average of all bubble normal points including the thickening point is also close to b (and b) The difference is less than e), that is, the average thickness of the full-circumferential bubble is close to b, and the full-thickness thickness control mechanism lowers the total thickness of the bubble according to the detection result of the bubble thickness detector, so that the total bubble is averaged. The thickness becomes smaller as a;
(7)、在后续阶段的生产过程中,各原始凸点厚度控制机构保持第(2)步骤记录的工作参数;而所有正常点厚度控制机构均衡地轮流选取其中一部分进行增厚操作,并保持在每一时刻进行增厚操作的正常点厚度控制机构的总数量为第(5)步骤中记录的数值M,且M个进行增厚操作的正常点厚度控制机构的工作参数与第(5)步骤记录的工作参数一一对应相同;在每一时刻,除了进行增厚操作的M个正常点厚度控制机构之外,其余不进行增厚操作的正常点厚度控制机构仍然以原始工作参数进行工作;膜泡厚度检测器不断检测膜泡周向上各点的实际厚度,全周厚度控制机构使全周膜泡各点的平均厚度保持为a。(7) In the subsequent production process, each original bump thickness control mechanism maintains the operating parameters recorded in step (2); and all normal point thickness control mechanisms alternately select one of them for thickening operation and maintain The total number of normal point thickness control mechanisms that perform the thickening operation at each time is the value M recorded in the step (5), and the operating parameters of the normal point thickness control mechanisms of the M thickening operations and the (5) The working parameters recorded in the step are the same one-to-one; at each moment, except for the M normal point thickness control mechanisms that perform the thickening operation, the normal point thickness control mechanism that does not perform the thickening operation is still performed with the original working parameters. The bubble thickness detector continuously detects the actual thickness of each point in the circumferential direction of the bubble, and the full-thickness thickness control mechanism maintains the average thickness of each point of the entire bubble at a.
上述步骤(2)中,“控制调整后原始凸点的预计厚度h位于以下区
间范围:a+0.7f>h>a+0.2f,”,这并不是指在该区间选一个点作为控制目标,而是控制预计厚度h落入该区间范围即可,由于这个减厚后的目标厚度是一个比较大的区间范围,现有的局部厚度控制机构能够实现这个粗略得控制标准,因此没有困难,也没有特殊要求。In the above step (2), "the estimated thickness h of the original bump after the control adjustment is located in the following area
The range is: a+0.7f>h>a+0.2f,”, this does not mean that a point is selected as the control target in the interval, but the expected thickness h falls within the range, because of this thickness reduction The target thickness is a relatively large range of ranges, and the existing local thickness control mechanism can achieve this rough control standard, so there is no difficulty and no special requirements.
本发明具有以下优点和效果:The invention has the following advantages and effects:
一、本发明生产的膜泡收卷后,薄膜的偏厚点和累积偏厚程度沿卷材的轴向、周向呈现出均匀分配,避免爆筋现象,且可省略传统的机械旋转牵引工艺和设备。1. After the bubble produced by the invention is wound, the partial thickness and the cumulative thickness of the film are uniformly distributed along the axial and circumferential directions of the coil to avoid the phenomenon of bursting, and the traditional mechanical rotating traction process can be omitted. And equipment.
二、本发明的原始凸点不必过分加热使其厚度被完全削平,因此避免破泡、膜泡坍塌的问题。2. The original bump of the present invention does not have to be excessively heated so that its thickness is completely flattened, thereby avoiding the problem of bubble collapse and bubble collapse.
三、本发明虽然和传统工艺一样,只能粗略控制膜泡具体局部点的厚度,但却能够精确控制所有膜泡正常点的平均实际厚度(这是因为,一个变化参数除以约100的样本总数后,该变化参数对所有样本的影响程度将比自身变化程度降低约100倍,这意味着变化参数对平均值影响的精确度比自身变化精确度提高两个数量级),因此,本发明能使所有膜泡正常点的平均实际厚度比较精确地等于各原始凸点调整后的平均厚度,进而使膜卷整体厚度均匀。3. Although the present invention, like the conventional process, can only roughly control the thickness of the specific local point of the bubble, it can precisely control the average actual thickness of all the normal points of the bubble (this is because a variation parameter is divided by about 100 samples). After the total number, the degree of influence of the variation parameter on all samples will be reduced by about 100 times than the degree of self-change, which means that the accuracy of the influence of the variation parameter on the average value is two orders of magnitude higher than the accuracy of the self-change, and therefore, the present invention can The average actual thickness of all the normal points of the bubble is accurately equal to the average thickness of each original bump adjusted, thereby making the overall thickness of the film roll uniform.
四、本发明通过削厚(将凸点削掉一部分厚度)、加厚(将正常点稍微加厚使其与削后的凸点基本等厚)、再整体拉薄的方式,实现膜泡最终总体平均厚度符合产品质量要求、局部又不会爆筋的目的;其中,虽然正常点成为增厚点,但由于所有正常点均衡轮流进行增厚,因此不会出现增厚点累积而产生爆筋的问题。4. The present invention achieves the final bubble by thickening (shaving a part of the thickness of the bump), thickening (slightly thickening the normal point to be substantially equal to the thickness of the sharpened bump), and then thinning the whole. The overall average thickness meets the requirements of product quality and does not explode locally. Among them, although the normal point becomes a thickening point, since all normal points are balanced and thickened, there is no accumulation of thickening points and bursting. The problem.
图1是冷却风环对膜泡实施冷却的结构原理示意图。Fig. 1 is a schematic view showing the structure of a cooling air ring for cooling a bubble.
图2是图1中各主要部件的水平投影位置关系示意图。FIG. 2 is a schematic diagram showing the horizontal projection position relationship of each main component in FIG. 1. FIG.
图3是局部厚度控制机构的原理示意图。Figure 3 is a schematic diagram of the principle of a local thickness control mechanism.
一种吹膜生产工艺,采用的吹膜设备与图1、图2、图3所示结构类同,它设有挤出模头,挤出模头设有圆环形挤出口,挤出模头上方设有圆环形的冷却风环,冷却风环的导风夹层利用多片分隔板将圆环形导风夹层
从周向上均匀分隔为100个径向通道(图3中的径向通道数量只是示意性的,为了图面简洁而没有精确画出100个),每个径向通道对应设有局部厚度控制机构,共有100个局部厚度控制机构,局部厚度控制机构具体采用电热元件,各个电热元件沿周向均匀布置,每个电热元件位于一个冷却风环的径向通道里面;还设有全周厚度控制机构、膜泡厚度检测器;全周厚度控制机构具体包括有牵引夹辊主导的竖向拉伸机构、空压机主导的横向拉伸机构。A blown film production process, the blown film equipment is similar to the structure shown in Fig. 1, Fig. 2, Fig. 3, which is provided with an extrusion die, the extrusion die is provided with a circular extrusion port, and an extrusion die An annular cooling air ring is arranged above the head, and the air guiding interlayer of the cooling air ring uses a plurality of partition plates to sandwich the circular air guiding layer
It is evenly divided into 100 radial channels from the circumferential direction (the number of radial channels in Figure 3 is only schematic, and 100 are not accurately drawn for the sake of simplicity), each radial channel is provided with a local thickness control mechanism. There are 100 partial thickness control mechanisms, and the local thickness control mechanism specifically adopts electric heating elements, and each electric heating element is evenly arranged in the circumferential direction, and each electric heating element is located in a radial passage of a cooling air ring; and a full-thickness thickness control mechanism is also provided. The bubble thickness detector; the full-thickness thickness control mechanism specifically includes a vertical stretching mechanism led by the traction nip roller and a transverse stretching mechanism led by the air compressor.
生产开始之前,设定膜泡厚度目标值a为100微米,并根据机械设备和生产工艺、材质的特点,确定出原始凸点的认定条件:如果某个方位的膜泡厚度检测值比膜泡厚度目标值100微米超出10微米时(其中10微米为膜泡厚度正常偏差值f,该数值f是根据收卷质量等级要求、薄膜厚度、设备精度等因素综合决定、事先设定),则该方位认定为机械问题而引起的原始凸点,原始凸点以外的其它方位点认定为正常点。再根据收卷质量等级要求、薄膜厚度、设备精度等因素综合决定最大允许差值e的数值定为1.5微米,其中e为c和b两者的最大允许差值,c为包括增厚点在内的所有膜泡正常点的实际厚度平均值,b为膜泡各原始凸点调整后的原始凸点调整厚度的平均值。最大允许差值e的实际意义是:只要所有膜泡正常点调整后的最终厚度平均值与原始凸点调整后的厚度平均值相差不超过e(1.5微米),则认为符合收卷质量的要求。Before the start of production, the target value of the bubble thickness is set to 100 μm, and the conditions for the identification of the original bump are determined according to the characteristics of the mechanical equipment, the production process, and the material: if the bubble thickness in a certain direction is greater than the bubble When the thickness target value is 100 micrometers and exceeds 10 micrometers (10 micrometers is the normal deviation value f of the bubble thickness, the value f is comprehensively determined according to the requirements of the winding quality grade, film thickness, equipment accuracy, etc., and is set in advance) The original bump caused by the mechanical problem is determined by the orientation, and the other azimuth points other than the original bump are regarded as normal points. According to the quality requirements of the winding quality, film thickness, equipment accuracy and other factors, the maximum allowable difference e is determined to be 1.5 microns, where e is the maximum allowable difference between c and b, and c is the thickening point. The actual thickness average of all bubble normal points, b is the average value of the original bump adjustment thickness after adjustment of each original bump of the bubble. The practical significance of the maximum allowable difference e is that as long as the average thickness of the final thickness of all the bubble normal points does not differ from the average thickness of the original bump adjustment by e (1.5 micrometers), it is considered to meet the requirements of the winding quality. .
该工艺包括以下步骤:(1)、挤出模头的圆环形挤出口不断挤出圆环状的膜坯,膜坯挤出后经过吹胀和冷却风环的冷却而形成膜泡,开始时,冷却风环的电热元件均以相同加热功率工作,该加热功率为原始工作参数,记录该原始工作参数;The process comprises the following steps: (1), the annular extrusion port of the extrusion die continuously extrude the annular film blank, and after the film blank is extruded, the inflating and the cooling air ring are cooled to form a bubble, and the film begins. When the heating elements of the cooling air ring are all operated at the same heating power, the heating power is the original working parameter, and the original working parameters are recorded;
膜泡厚度检测器不断检测膜泡周向上各点的初始厚度,当膜泡周向上某个方位点的初始厚度达到110微米以上(比膜泡厚度目标值100微米超出设定的10微米以上,其中10微米为膜泡厚度正常偏差值f)时,将膜泡在该方位的点认定为原始凸点,原始凸点以外的其它方位点认定为正常点,正常点对应方位的局部厚度控制机构称为正常点厚度控制机构;原始凸点对应方位的局部厚度控制机构称为原始凸点厚度控制机构;The bubble thickness detector continuously detects the initial thickness of each point in the circumferential direction of the bubble, and the initial thickness of a certain azimuth point in the bubble circumferential direction reaches 110 μm or more (above the target value of 100 μm of the bubble thickness exceeds the set value of 10 μm or more, When 10 micron is the normal deviation value f) of the bubble thickness, the point at which the bubble is in the azimuth is regarded as the original bump, and the other azimuth points other than the original bump are regarded as the normal point, and the local thickness control mechanism corresponding to the orientation of the normal point It is called a normal point thickness control mechanism; the local thickness control mechanism of the original bump corresponding orientation is called the original bump thickness control mechanism;
(2)、各原始凸点厚度控制机构件开始进行膜泡减厚操作,即原始
凸点对应方位的电热元件加大电热功率,提高原始凸点处的膜泡温度,使膜泡原始凸点的厚度降低,且控制调整后原始凸点的预计厚度h位于以下区间范围:a+0.7f>h>a+0.2f,即控制调整后原始凸点的预计厚度h小于107微米而大于102微米;膜泡厚度检测器继续不断检测膜泡各点的实际厚度,计算出膜泡各个原始凸点调整后的原始凸点调整厚度的平均值b,并记录进行减厚操作后的各原始凸点厚度控制机构的工作参数,即记录进行减厚操作后的各原始凸点厚度控制机构的电热元件的电热功率;(2), each original bump thickness control machine component starts the bubble thinning operation, that is, the original
The electric heating element corresponding to the azimuth of the bump increases the electric heating power, increases the bubble temperature at the original bump, and reduces the thickness of the original bump of the bubble, and the estimated thickness h of the original bump after the control adjustment is in the following range: a+ 0.7f>h>a+0.2f, that is, the estimated thickness h of the original bump after the control adjustment is less than 107 μm and larger than 102 μm; the bubble thickness detector continuously detects the actual thickness of each point of the bubble, and calculates each bubble. The original bump adjusted original bump adjusts the average value b of the thickness, and records the working parameters of each original bump thickness control mechanism after the thickness reduction operation, that is, records the original bump thickness control mechanism after performing the thickness reduction operation Electric heating power of the electric heating element;
(3)、在所有正常点厚度控制机构中,选取其中一部分正常点厚度控制机构进行膜泡增厚操作,膜泡增厚操作的方式是降低对应方位的电热元件的电热功率,使对应方位的膜泡局部温度下降,被选中进行增厚操作的正常点厚度控制机构对应方位的膜泡正常点称为增厚点(增厚点仍然理解为属于正常点的组成部分);膜泡厚度检测器继续不断检测膜泡各点的实际厚度,计算出包括增厚点在内的所有膜泡正常点的平均实际厚度c;不被选中进行膜泡增厚操作的正常点厚度控制机构仍然保持原始工作参数;(3) In all the normal point thickness control mechanisms, a part of the normal point thickness control mechanism is selected for the bubble thickening operation, and the way of the bubble thickening operation is to reduce the electric heating power of the corresponding electric heating element, so that the corresponding orientation The local temperature of the bubble decreases, and the normal point of the normal thickness control mechanism selected for the thickening operation is called the thickening point (the thickening point is still understood to be a component of the normal point); the bubble thickness detector Continue to continuously detect the actual thickness of each point of the bubble, calculate the average actual thickness c of all the normal points of the bubble including the thickening point; the normal point thickness control mechanism that is not selected for the bubble thickening operation still maintains the original work parameter;
(4)、计算c和b两者的差值绝对值d,d=|c-b|;其中c为包括增厚点在内的所有膜泡正常点在增厚操作后的实际厚度平均值,b为膜泡各原始凸点在减厚操作后的原始凸点调整厚度的平均值;(4) Calculate the absolute value d of the difference between c and b, d=|cb|; where c is the actual thickness average of all normal bubble points including the thickening point after the thickening operation, b Adjusting the average value of the thickness of the original bumps of the bubble before the thickness reduction operation;
(5)、比较d和e的大小,其中e为c和b两者的最大允许差值;(5) Comparing the sizes of d and e, where e is the maximum allowable difference between c and b;
如果比较结果为d≤e,则意味着所有膜泡正常点的平均实际厚度与原始凸点的平均实际厚度差值不大于1.5微米,属于可以承受的偏差范围,因此,说明增厚操作达到目的,记录在此种状态下进行增厚操作的正常点厚度控制机构的数量M,以及每个进行增厚操作的正常厚度控制机构(电热元件)的工作参数(电热功率),并开始第(6)步骤;If the comparison result is d ≤ e, it means that the difference between the average actual thickness of all normal points of the bubble and the average actual thickness of the original bump is not more than 1.5 μm, which is an acceptable tolerance range. Therefore, the thickening operation is achieved. Recording the number M of the normal point thickness control mechanisms for performing the thickening operation in this state, and the operating parameters (electrical heating power) of the normal thickness control mechanism (electric heating element) for each thickening operation, and starting the sixth (6) )step;
如果比较结果为d>e,意味着所有膜泡正常点的平均实际厚度与原始凸点的平均实际厚度差值大于1.5微米,超出承受的偏差范围,必须继续调整,则进一步比较c和b两者大小;If the comparison result is d>e, it means that the difference between the average actual thickness of all normal points of the bubble and the average actual thickness of the original bump is greater than 1.5 micrometers, beyond the tolerance range, and the adjustment must be continued, then the c and b are further compared. Size
如果比较结果为b>c,则将步骤(3)中进行膜泡增厚操作的正常点厚度控制机构的数量逐步调高,每将进行膜泡增厚操作的正常点厚度控制机构的数量调高一个,虽然不能精确预计对应局部正常点的膜泡厚度增加
几微米,但却可以预计,包括增厚点在内的所有正常点(100个点)的平均实际厚度将增加不足0.1微米,这个控制精度是远远超出需要的,在逐步调高进行膜泡增厚操作的正常点厚度控制机构数量的过程中,重复检测包括增厚点在内的所有正常点的平均实际厚度并计算出新的平均值c,重复计算新的平均值c和b两者新的差值绝对值d,重复比较d和e的大小;直至d≤e,当d≤e,意味着所有膜泡正常点的平均实际厚度与原始凸点的平均实际厚度差值不大于1.5微米,进入可以承受的偏差范围,因此,说明增厚操作达到目的,记录在此种状态下进行增厚操作的正常点厚度控制机构的数量M,以及每个进行增厚操作的正常点厚度控制机构(电热元件)的工作参数(电热功率),然后开始第(6)步骤;If the comparison result is b>c, the number of normal point thickness control mechanisms for performing the bubble thickening operation in step (3) is gradually increased, and the number of normal point thickness control mechanisms for each bubble thickening operation is adjusted. Higher one, although it is not possible to accurately predict the increase in bubble thickness corresponding to the local normal point
A few microns, but it is expected that the average actual thickness of all normal points (100 points) including the thickening point will increase by less than 0.1 micron. This control accuracy is far beyond the need to gradually increase the bubble. During the process of increasing the number of normal point thickness control mechanisms of the operation, the average actual thickness of all normal points including the thickening point is repeatedly detected and a new average value c is calculated, and the new average values c and b are repeatedly calculated. The new absolute value of the difference d, repeatedly compares the size of d and e; until d ≤ e, when d ≤ e, means that the average actual thickness of all normal points of the bubble and the average actual thickness of the original bump are not more than 1.5 Micron, enters the range of tolerance that can be tolerated, therefore, indicates that the thickening operation achieves the purpose, records the number M of the normal point thickness control mechanism for thickening operation in this state, and the normal point thickness control for each thickening operation Operating parameters (electrical heating power) of the mechanism (electric heating element), and then starting step (6);
如果比较结果为c>b,则将步骤(3)中进行膜泡增厚操作的正常点厚度控制机构的数量逐步调低,进行膜泡增厚操作的正常点厚度控制机构的数量每调低一个(即是将其中一个进行膜泡增厚操作的正常点厚度控制机构恢复为原始工作参数),虽然不能精确预计对应局部点的膜泡厚度减少几微米,但却可以预计,包括增厚点在内的所有正常点(100个点)的平均实际厚度将降低不足0.1微米,这个控制精度是远远超出需要的,在逐步调低进行膜泡增厚操作的正常点厚度控制机构数量的过程中,重复检测包括增厚点在内的所有正常点的平均实际厚度并计算出新的平均值c,重复计算新的平均值c和b两者新的差值绝对值d,重复比较d和e的大小,直至d≤e,当d≤e,意味着所有膜泡正常点的平均实际厚度与原始凸点的平均实际厚度差值不大于1.5微米,进入可以承受的偏差范围,因此,说明增厚操作达到目的,记录在此种状态下进行增厚操作的正常点厚度控制机构的数量M,以及每个进行增厚操作的正常点厚度控制机构(电热元件)的工作参数(电热功率),然后开始第(6)步骤;If the comparison result is c>b, the number of normal point thickness control mechanisms for performing the bubble thickening operation in step (3) is gradually lowered, and the number of normal point thickness control mechanisms for performing the bubble thickening operation is lowered. One (ie, restores the normal point thickness control mechanism for one of the bubble thickening operations to the original operating parameters), although it is not possible to accurately predict that the bubble thickness of the corresponding local point is reduced by a few microns, but it can be expected, including thickening points. The average actual thickness of all normal points (100 points) within the range will be reduced by less than 0.1 micron. This control accuracy is far beyond the need to gradually reduce the number of normal thickness control mechanisms for bubble thickening operations. Medium, repeatedly detecting the average actual thickness of all normal points including the thickening point and calculating a new average value c, repeatedly calculating the new absolute value d of the new average values c and b, repeating the comparison d and The size of e, until d ≤ e, when d ≤ e, means that the average actual thickness of all normal points of the bubble and the average actual thickness of the original bump are not more than 1.5 microns, into the tolerance range Therefore, it is explained that the thickening operation achieves the purpose, the number M of the normal point thickness control mechanisms for performing the thickening operation in this state, and the operation of the normal point thickness control mechanism (electric heating element) for each thickening operation are recorded. Parameter (electrical heating power), then start step (6);
(6)、在上述步骤(5)完成后,各原始凸点的实际厚度平均值为b,包括增厚点在内的所有膜泡正常点的平均实际厚度c也接近于b,此后,全周厚度控制机构根据膜泡厚度检测器的检测结果而调低膜泡全周厚度,具体为调高膜泡牵引速度,使全周膜泡平均厚度变小a;(6) After the completion of the above step (5), the actual thickness average of each original bump is b, and the average actual thickness c of all bubble normal points including the thickening point is also close to b, after which, The circumferential thickness control mechanism lowers the total thickness of the bubble according to the detection result of the bubble thickness detector, specifically, increases the bubble pulling speed, so that the average thickness of the whole cell bubble becomes smaller a;
(7)、在后续阶段的生产过程中,各原始凸点对应方位的局部厚度控制机构(电热元件)保持第(2)步骤记录的工作参数(电热功率),
而所有正常点厚度控制机构均衡地轮流选取其中一部分进行膜泡增厚操作,并保持在每一时刻进行增厚操作的正常点厚度控制机构的总数量为第(5)步骤记录的M个,且M个进行增厚操作的正常点厚度控制机构的电热元件的加热功率与第(5)步骤记录的加热功率一一对应相同;在每一时刻,除了进行增厚操作的M个正常点厚度控制机构之外,其余不进行增厚操作的正常点厚度控制机构仍然以原始工作参数进行工作;膜泡厚度检测器不断检测膜泡周向上各点的实际厚度,全周厚度控制机构(具体为竖向拉伸机构)使全周膜泡各点的平均厚度保持为100微米,此后可直接将膜泡收卷,而无需经过机械旋转牵引。由于上述步骤(7)中,每一个膜泡正常点作为增厚点的机会是均等的,即增厚点在膜泡周向上是不断等机会地轮换的,因此收卷后,增厚点不会导致爆筋现象。(7) In the subsequent production process, the local thickness control mechanism (electric heating element) corresponding to the orientation of each original bump maintains the operating parameter (electrical heating power) recorded in the step (2),
And all the normal point thickness control mechanisms alternately select one of them to perform the bubble thickening operation, and maintain the normal point thickness control mechanism at each moment for the thickening operation, which is the M records recorded in the step (5), And the heating power of the electric heating elements of the M normal thickness control mechanisms for performing the thickening operation is the same as the heating power recorded in the step (5); at each moment, except for the M normal point thicknesses for performing the thickening operation In addition to the control mechanism, the remaining normal thickness control mechanism that does not perform the thickening operation still works with the original working parameters; the bubble thickness detector continuously detects the actual thickness of each point in the bubble circumferential direction, and the full-thickness thickness control mechanism (specifically The vertical stretching mechanism maintains the average thickness of each point of the entire circumference of the bubble to 100 microns, after which the bubble can be wound directly without mechanically rotating. Since in the above step (7), the chance that each bubble is normal as a thickening point is equal, that is, the thickening point is continuously and alternately rotated in the bubble circumferential direction, so after the winding, the thickening point is not Will cause the phenomenon of bursting.
上述步骤(2)中,“控制调整后原始凸点的预计厚度h小于107微米而大于102微米”,由于这个减厚后的目标厚度是一个比较大的区间范围,现有的局部厚度控制机构能够实现这个粗略的控制标准,因此没有困难,也没有特殊要求。In the above step (2), "the estimated thickness h of the original bump after the control adjustment is less than 107 micrometers and larger than 102 micrometers", since the target thickness after the thickness reduction is a relatively large interval range, the existing partial thickness control mechanism This rough control standard can be achieved, so there is no difficulty and no special requirements.
上述实施例中,全周厚度控制机构也可采用空压机主导的横向拉伸机构,利用泡内气压的气压值控制膜泡全周厚度。In the above embodiment, the full-thickness thickness control mechanism may also adopt a transverse stretching mechanism dominated by the air compressor, and the bubble pressure is used to control the total thickness of the bubble.
上述实施例中,局部厚度控制机构也可采用安装在径向通道中的电动阀门,其工作参数为阀门开口大小,或者阀门开关状态,其增厚操作方式是加大阀门开口度,其减厚操作方式是减小阀门开口度。In the above embodiment, the partial thickness control mechanism can also adopt an electric valve installed in the radial passage, and the working parameter is the valve opening size or the valve switching state, and the thickening operation mode is to increase the valve opening degree, and the thickness is reduced. The mode of operation is to reduce the degree of valve opening.
上述实施例中,局部厚度控制机构的数值可以改为72个,也可改为144个,或者288个,或者360个,等等。In the above embodiment, the value of the local thickness control mechanism can be changed to 72, or can be changed to 144, or 288, or 360, and the like.
上述实施例的步骤(5)中,关于“将进行膜泡增厚操作的正常点厚度控制机构的数量逐步调低”的分步骤,也可改为逐步降低其中一部分增厚点的膜泡增厚操作的幅度,例如逐渐加大一部分增厚点的电热元件的功率,其结果也可使“包括增厚点在内的所有正常点的平均实际厚度”精细降低。In the step (5) of the above embodiment, the sub-step of "gradually lowering the number of the normal point thickness control means for performing the bubble thickening operation" may also gradually reduce the bubble increase of a part of the thickening point. The magnitude of the thick operation, such as gradually increasing the power of a portion of the thickened electric heating element, results in a fine reduction in the "average actual thickness of all normal points including the thickening point".
上述实施例的步骤(5)中,关于“将进行膜泡增厚操作的正常点厚度控制机构的数量逐步调高”的分步骤,也可改为逐步增加其中一部分增厚点的膜泡增厚操作的幅度,例如逐渐进一步降低一部分增厚点的电热元
件的功率,其结果也可使“包括增厚点在内的所有正常点的平均实际厚度”精细升高。In the step (5) of the above embodiment, the sub-step of "gradually increasing the number of normal point thickness control mechanisms for performing the bubble thickening operation" may also be carried out by gradually increasing the bubble growth of a part of the thickening points. The magnitude of the thick operation, such as the electric heating element that gradually reduces a part of the thickening point
The power of the piece, the result also allows the "average actual thickness of all normal points including the thickening point" to be finely increased.
本发明及其实施例中,关于膜泡厚度目标值a、膜泡厚度正常偏差值f、最大允许差值e可以根据实际收卷的卷材和质量要求具体确定,这些数值的取值主要根据产品质量要求而灵活确定,并不是本发明所要解决的问题。
In the present invention and its embodiments, the target value a of the bubble thickness, the normal deviation value f of the bubble thickness, and the maximum allowable difference e may be specifically determined according to the actual winding volume and quality requirements, and the values of these values are mainly based on The product quality requirements are flexible and determined, and are not the problems to be solved by the present invention.
Claims (1)
- 一种吹膜生产工艺,采用的吹膜设备设有挤出模头,挤出模头设有圆环形挤出口,挤出模头上方设有圆环形的冷却风环,冷却风环形成有至少72个局部厚度控制机构,各个局部厚度控制机构沿冷却风环的周向均匀布置;采用的吹膜设备还设有全周厚度控制机构、膜泡厚度检测器;其特征在于包括以下步骤:A blown film production process, the blown film device is provided with an extrusion die, the extrusion die is provided with a circular extrusion port, and a circular cooling air ring is arranged above the extrusion die, and a cooling air ring is formed. There are at least 72 partial thickness control mechanisms, and each partial thickness control mechanism is evenly arranged along the circumferential direction of the cooling air ring; the blown film device is further provided with a full-thickness thickness control mechanism and a bubble thickness detector; and the method includes the following steps :(1)、挤出模头的圆环形挤出口不断挤出圆环状的膜坯,膜坯挤出后经过吹胀和冷却而形成膜泡,各局部厚度控制机构均以相同工作参数工作,该工作参数称为原始工作参数,记录该原始工作参数;膜泡厚度检测器不断检测膜泡周向上各点的初始厚度;当膜泡周向上某个方位点的初始厚度比膜泡厚度设计值a超出的数值大于膜泡厚度正常偏差值f时,将膜泡在该方位的点认定为原始凸点,原始凸点以外其它方位的点认定为正常点,正常点对应方位的局部厚度控制机构称为正常点厚度控制机构;原始凸点对应方位的局部厚度控制机构称为原始凸点厚度控制机构;(1) The annular extrusion port of the extrusion die continuously extrudes the annular film blank, and after the film blank is extruded, it is inflated and cooled to form a bubble, and each partial thickness control mechanism works with the same working parameters. The working parameter is called the original working parameter, and the original working parameter is recorded; the bubble thickness detector continuously detects the initial thickness of each point in the circumferential direction of the bubble; when the initial thickness of the azimuth point in the circumferential direction of the bubble is larger than the thickness of the bubble When the value a exceeds the normal deviation value f of the bubble thickness, the point at which the bubble is at the azimuth is regarded as the original bump, and the point other than the original bump is regarded as the normal point, and the local thickness of the normal point corresponds to the local thickness control. The mechanism is called a normal point thickness control mechanism; the local thickness control mechanism corresponding to the original bump is called the original bump thickness control mechanism;(2)、各原始凸点厚度控制机构开始进行膜泡减厚操作,改变工作参数,使膜泡原始凸点的厚度降低,且控制调整后原始凸点的预计厚度h位于以下区间范围:a+0.7f>h>a+0.2f;膜泡厚度检测器继续不断检测膜泡各点的厚度,计算出膜泡各原始凸点在减厚操作后的原始凸点调整厚度的平均值b,并记录进行减厚操作后的各原始凸点厚度控制机构的工作参数,f为膜泡厚度正常偏差值;(2) The original bump thickness control mechanism starts the bubble thinning operation, changes the working parameters, and reduces the thickness of the original bump of the bubble, and the estimated thickness h of the original bump after the control adjustment is in the following range: a +0.7f>h>a+0.2f; the bubble thickness detector continuously detects the thickness of each point of the bubble, and calculates the average value b of the original bump adjustment thickness of each original bump of the bubble after the thickness reduction operation, And record the working parameters of each original bump thickness control mechanism after the thickness reduction operation, and f is the normal deviation value of the bubble thickness;(3)、在所有正常点厚度控制机构中,选取其中一部分正常点厚度控制机构进行膜泡增厚操作,改变工作参数,被选中进行增厚操作的正常点厚度控制机构对应方位的膜泡正常点称为增厚点;膜泡厚度检测器继续不断检测膜泡各点的厚度,计算出包括增厚点在内的所有膜泡正常点在增厚操作后的平均实际厚度c;不被选中进行膜泡增厚操作的正常点厚度控制机构仍然保持原始工作参数;(3) In all the normal point thickness control mechanisms, select some of the normal point thickness control mechanisms to perform the bubble thickening operation, change the working parameters, and the normal point thickness control mechanism selected for the thickening operation is normal. The point is called the thickening point; the bubble thickness detector continues to continuously detect the thickness of each point of the bubble, and calculates the average actual thickness c of all the normal points of the bubble including the thickening point after the thickening operation; The normal point thickness control mechanism for performing the bubble thickening operation still maintains the original operating parameters;(4)、计算c和b两者的差值绝对值d,其中c为包括增厚点在内的所有膜泡正常点在增厚操作后的实际厚度平均值,b为膜泡各原 始凸点在减厚操作后的原始凸点调整厚度的平均值,d=|c-b|;(4) Calculate the absolute value d of the difference between c and b, where c is the actual thickness average of all normal bubble points including the thickening point after the thickening operation, and b is the bubble original The average value of the original bump adjustment thickness of the starting bump after the thickness reduction operation, d=|c-b|;(5)、比较d和e的大小,其中e为c和b两者的最大允许差值;如果d≤e,则记录在此种状态下进行增厚操作的正常点厚度控制机构的数量M,以及每个进行增厚操作的正常点厚度控制机构的工作参数,并开始第(6)步骤;(5) Comparing the sizes of d and e, where e is the maximum allowable difference between c and b; if d ≤ e, the number of normal point thickness control mechanisms for performing the thickening operation in this state is recorded M And the operating parameters of each normal thickness control mechanism for performing the thickening operation, and starting the step (6);如果d>e,则进一步比较c和b两者大小;If d>e, further compare the size of both c and b;如果c<b,则将步骤(3)中进行膜泡增厚操作的正常点厚度控制机构的数量逐步调高,或将其中个别正常点厚度控制机构的增厚程度逐步调高,在逐步调高过程中,重复检测包括增厚点在内的所有正常点的平均实际厚度并计算出新的实际厚度平均值c,重复计算新的平均值c和b两者差值绝对值d,重复比较d和e的大小,直至d≤e,并记录在此种状态下进行增厚操作的正常点厚度控制机构的数量M,以及每个进行增厚操作的正常点厚度控制机构的工作参数,然后开始第(6)步骤;If c<b, the number of normal point thickness control mechanisms for performing the bubble thickening operation in step (3) is gradually increased, or the thickness of the individual normal point thickness control mechanism is gradually increased, and gradually adjusted. In the high process, repeat the average actual thickness of all normal points including the thickening point and calculate the new actual thickness average c, and repeatedly calculate the absolute value d of the new average values c and b, and repeat the comparison. The size of d and e up to d ≤ e, and record the number M of normal point thickness control mechanisms for thickening operation in this state, and the operating parameters of the normal point thickness control mechanism for each thickening operation, and then Start step (6);如果c>b,则将步骤(3)中进行膜泡增厚操作的正常点厚度控制机构的数量逐步调低,或逐步将其中个别正常点厚度控制机构的增厚幅度调低,在逐步调低过程中,重复检测包括增厚点在内的所有正常点的平均实际厚度并计算出新的平均值c,重复计算新的平均值c和b两者新的差值绝对值d,重复比较d和e的大小,直至d≤e,并记录在此种状态下进行增厚操作的正常点厚度控制机构的数量M,以及每个进行增厚操作的正常点厚度控制机构的工作参数,然后开始第(6)步骤;If c>b, the number of normal point thickness control mechanisms for performing the bubble thickening operation in step (3) is gradually lowered, or the thickness of the individual normal point thickness control mechanism is gradually lowered, and gradually adjusted. In the low process, the average actual thickness of all normal points including the thickening point is repeatedly detected and a new average value c is calculated, and the new absolute value d of the new average values c and b is repeatedly calculated, and the comparison is repeated. The size of d and e up to d ≤ e, and record the number M of normal point thickness control mechanisms for thickening operation in this state, and the operating parameters of the normal point thickness control mechanism for each thickening operation, and then Start step (6);(6)、在上述步骤(5)完成后完成后,全周厚度控制机构根据膜泡厚度检测器的检测结果而调低膜泡全周厚度,使全周膜泡平均厚度变小为a;(6), after completion of the above step (5) is completed, the full-thickness thickness control mechanism according to the detection result of the bubble thickness detector to reduce the thickness of the entire bubble, so that the average thickness of the total bubble becomes smaller a;(7)、在后续阶段的生产过程中生产过程中,各原始凸点厚度控制机构保持第(2)步骤记录的工作参数;而所有正常点厚度控制机构均衡地轮流选取其中一部分进行增厚操作,并保持在每一时刻进行增厚操作的正常点厚度控制机构的总数量为第(5)步骤中记录的数值M,且M个进行增厚操作的正常点厚度控制机构的工作参数与第(5) 步骤记录的工作参数一一对应相同;在每一时刻,除了进行增厚操作的M个正常点厚度控制机构之外,其余不进行增厚操作的正常点厚度控制机构仍然以原始工作参数进行工作;膜泡厚度检测器不断检测膜泡周向上各点的实际厚度,全周厚度控制机构使全周膜泡各点的平均厚度保持为a。 (7) In the production process in the subsequent stage of production, each original bump thickness control mechanism maintains the working parameters recorded in step (2); and all normal point thickness control mechanisms alternately select one of them to perform thickening operation And maintaining the normal point thickness control mechanism at each time for the thickening operation is the value M recorded in the step (5), and the operating parameters of the normal thickness control mechanism of the M thickening operations and the (5) The working parameters recorded in the step are the same one-to-one; at each moment, except for the M normal point thickness control mechanisms that perform the thickening operation, the normal point thickness control mechanism that does not perform the thickening operation is still performed with the original working parameters. The bubble thickness detector continuously detects the actual thickness of each point in the circumferential direction of the bubble, and the full-thickness thickness control mechanism maintains the average thickness of each point of the entire bubble at a.
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