Device for adjusting gap of wide-groove die head
By introducing a double-sided lever structure driven by stepper motor into the adjustment element of the wide-slot die head, the problems of slow adjustment, high cost and insufficient heat transfer in the prior art are solved, and the effects of high resolution profile adjustment and low energy demand are achieved.
Patent Information
- Application Number
- CN202380073847.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-10-18
- Filing Date
- 2023-10-18
- Publication Date
- 2025-05-23
AI Technical Summary
The prior art has problems such as high cost, slow adjustment, large material loss and short service life of the equipment when adjusting the gaps of wide groove die heads, especially in terms of high-resolution profile adjustment and equipment heat transfer.
Each adjustment element is adopted to include a driver, which is a stepper motor, and the actuating push rod is hingedly connected to the long arms of the lever on both sides, and the short arms of the lever are cooperated with a linearly guided pressure pin, which acts on the flexible lip to adjust the gap. The device provides the necessary adjustment force through a double-sided lever structure, reducing energy demand and reducing heat transfer.
High resolution profile adjustment over the entire width of the wide slot die head is achieved, reducing adjustment costs and material losses, improving equipment life, and significantly reducing energy demand and heat transfer.
Smart Images
Figure CN120035508A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a device for adjusting the gap of a wide slot die for manufacturing a flat web extruded product such as a film, wherein the wide slot die has a flexible lip with a plurality of adjustment elements arranged at regular intervals along its length for adjusting the gap profile of the lip. Background Art
[0002] Wide slot dies are used, for example, in extrusion plants for the manufacture of plastic films and sheets, but also for coating processes. In these extrusion plants, thermoplastics are melted and then discharged through the gap of the wide slot die in order to produce the material in film form. In this case, it is desirable that the produced film web has a uniform thickness or a predetermined profile over the entire width. In order to achieve this, the gap has to be preset to the desired thickness depending on the manufacturing process. After the first start-up phase, the thickness profile of the produced film web can be measured in order to make fine adjustments. Depending on the material, the process speed and the plant-specific parameters, deviations in the thickness profile can occur during the manufacturing process, which can be compensated by adjusting the height of the die gap at several points over the entire width of the wide slot die with the aid of adjustment elements on the flexible lip.
[0003] In the simplest case, these adjustment elements are screws, which are each turned manually and press with their lower end on the flexible lip in order to adjust the die gap. They require an expert who is familiar with the equipment to set them. Adjustments in the event of deviations during operation are difficult and slow, which leads to material losses and associated additional costs. In addition, in the case of a product change, there is a longer downtime of the equipment until all adjustment elements are reset one by one.
[0004] In order to allow in particular a fine adjustment of the profile during operation, in practice, hot bolt units are often used in the adjusting elements. In most cases, the rough presetting of the equipment relative to the desired product is still done manually by means of adjusting screws. Thus, the gap height can be preset in the range of, for example, 1 to 3 mm. Then, during operation, fine adjustments are made according to the resulting thickness profile by means of hot bolts (also called thermal expansion bolts) on each adjusting element. These allow fine adjustment of the die gap in the range of about 100 μm to 300 μm. Hot bolts are thermal adjustment elements that expand or contract due to the provided heating power and adjust the flexible lip and thus the die gap. However, these hot bolts always require a relatively high energy supply to provide the heating power, which in general leads to considerable additional operating costs in wider equipment. In addition, during the adjustment process, the corresponding bolts take some time to heat up or cool down, with the result that these hot bolts react slowly, which in turn leads to increased material losses. Finally, in the case of a product change, the adjustment must be made manually again due to the small possible adjustment path, which leads to an increased service life of the above-mentioned equipment.
[0005] EP 265700A1 discloses a device for adjusting a wide slot die, in which a screwdriver movable on a crossbar extending parallel to the wide slot die is used to actuate an adjusting screw of an adjusting element, which otherwise has to be actuated manually. Thus, the adjusting element can be actuated automatically when the product is changed, and the thickness profile can also be adjusted during continuous operation. In this case, the disadvantage is that the device has a relatively high control cost so that the screwdriver is correctly connected to the adjusting screw every time. In addition, in this case, only one adjusting screw can be operated at a time, which, although faster than manual operation due to automation, is still relatively slow, especially during continuous operation. The adjusting screw of the adjusting element also has the problem that it is easy to change its position during operation and therefore needs to be readjusted frequently.
[0006] In practice, automatic adjustment systems with multiple motors for a single adjustment screw mean that fewer adjustment elements can be placed side by side. Since the motors have to provide corresponding power, they cannot be made so small in terms of construction, so that the usually desired distance of about 2.5 cm between two adjustment elements cannot be maintained. In addition, due to the many motors, the corresponding equipment is very expensive, but at the same time does not allow high-resolution profile adjustment over the entire width of the die. Summary of the invention
[0007] The object of the present invention is therefore to provide a device for adjusting the gap of a wide slot die which eliminates the above-mentioned disadvantages and allows a high-resolution profile adjustment over the entire width of the wide slot die. The cost of each adjusting element should be kept at a low level and the adjusting elements should be held in the respective adjustment position in a self-locking manner to avoid frequent readjustments. The adjusting elements should also be compact enough to be placed closely side by side along the flexible lip of the wide slot die. During operation, a rapid and precise adjustment of all adjusting elements simultaneously in the coarse adjustment area and the fine adjustment area is possible. Furthermore, the device should have only a slight heat transfer from the wide slot die, in particular from the flexible lip, to the device itself.
[0008] The invention achieves this object in that each adjusting element comprises a drive, preferably in the form of a stepper motor, wherein the drive actuates a push rod, which is articulatedly connected to a long arm of a two-sided lever, and wherein the short arm of the lever cooperates with a linearly guided pressure pin, which in turn acts on the flexible lip, in order to adjust the gap in the area. By means of an arrangement with two-sided levers, the forces required for the adjustment path can be applied with a correspondingly small and advantageous drive, for example in the form of an electric stepper motor. Due to the compact design, a number of these adjusting elements can be economically placed at a small distance from each other along the wide slot die. Since each adjusting element is directly controlled, all adjusting elements can be adjusted simultaneously, so that rough adjustments during product changes and fine adjustments during operation can be carried out accurately and quickly. In addition, the device has a significantly lower energy demand than known hot bolt devices, which must be permanently supplied with energy to maintain the profile. On the other hand, the device according to the invention consumes energy only during the adjustment process itself. By applying the force in the front area of the flexible lip by means of a linearly guided pressure pin, very precise adjustments can also be made with very little force consumption, which adjustments do not change over time. The double-sided lever allows for a significant reduction in force during adjustment compared to devices where all lever forces act only on the pivot point of the flexible lip. Since the lever has an additional pivot point, the lever force can be adjusted very easily, depending on the application, by moving the pivot point on the lever or changing the lever length, without affecting the adjustment accuracy, especially in the fine adjustment range. The device can therefore be adapted to a variety of wide slot die devices with different force requirements simply by modifying the components of the lever.
[0009] According to a preferred embodiment, it is provided that the push rod is a spindle with an external thread, which engages with an internally threaded bushing rotatable by the driver and connected to a joint on the long arm of the lever, or conversely, the spindle is directly rotatably supported by the driver and engages with an internally threaded bushing of a joint connected to the long arm of the lever. This embodiment is particularly inexpensive to manufacture and results in self-locking of the pressure pin, thereby effectively preventing its adjustment during operation.
[0010] In this case, a further preferred feature is that the two-sided lever is an angle lever, wherein the long arm of the lever is arranged in approximately the same longitudinal direction as the pressure pin and the short arm of the lever extends approximately perpendicularly to the longitudinal direction of the pressure pin. In this way, each adjustment element can be realized in a particularly space-saving and compact manner and can be mounted on the device.
[0011] Another preferred feature is that the adjustment elements are arranged along the wide slot die in the area of the pressure pins at a distance of about 2 cm to 3 cm, preferably about 2.5 cm from each other. Thus, the thickness profile can be adjusted with high resolution over the entire width of the wide slot die.
[0012] According to a preferred embodiment, another feature is that in the region of the drive, the adjusting elements are arranged in two rows extending parallel to the wide slot die head, so that the adjusting elements of one row and the adjusting elements of the other row are alternately adjacent to each other. If the distance between the adjusting elements is particularly close, they can be divided into two rows, which is efficient and space-saving.
[0013] Another preferred feature is that the pressure pin is guided to move linearly in a connecting element, wherein the connecting element is used to connect the device to the wide slot die, and wherein the connecting element can be supported in a corresponding seat on the wide slot die by two webs. In addition, the connecting element can include a heat-insulating material or coating. Therefore, the device can be thermally decoupled from the wide slot die to a large extent, because it is only in contact with the wide slot die in the area of the two webs and through the tip of the pressure pin. The flexible lip of the wide slot die usually has its own heating device so that the material to be extruded has a suitable temperature at the outlet gap. It is hoped that the energy introduced here will not be dissipated through the regulating device. Otherwise, the high heat transfer from the wide slot die to the regulating device will lead to problems with film quality, or at least to energy losses, because more heating power must be introduced into the wide slot die and then released to the environment only in the regulating device.
[0014] In this case, a further preferred feature is that the pressure pin tapers or is rounded at both ends so that the contact points between the flexible lip of the wide slot die and the pressure pin and between the pressure pin and the two side levers are as small as possible or almost point-shaped, with the result that only a slight direct heat transfer between these components is possible. Due to the mostly heated flexible lip of the wide slot die and the subsequent few essentially point-shaped contact points with the two side levers, only a slight direct heat transfer between the wide slot die and the adjustment device occurs even during long operation.
[0015] Finally, another preferred feature is that a control unit for all drives of all adjusting elements connected to the wide slot die is provided, wherein the control unit brings the individual adjusting elements to the desired position based on sensor data about the instantaneous thickness profile of the extruded product and / or based on user input. Existing devices can determine the thickness profile of the produced product in different ways during the extrusion process and provide these data to the operator. The corresponding control unit can directly process this data in order to adapt the individual adjusting elements to the desired profile at the same time. The user input can also enter a rough adjustment on the profile, for example during a product change, after which all adjusting elements are quickly adjusted to the newly entered profile at the same time. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The invention will now be described in more detail with the aid of embodiments and with the aid of the accompanying drawings. In the drawings:
[0017] Figure 1 shows a schematic cross-sectional view through an adjusting element;
[0018] Figure 2 a schematic detailed front view showing a plurality of adjustment elements arranged in two rows; and
[0019] Figure 3 A schematic cross-sectional view in the region of the pressure pin and the connecting element at the wide slot die is shown. DETAILED DESCRIPTION
[0020] Figure 1 A wide slot die 2 with an adjusting element 4 according to the invention is shown very schematically in a sectional view. The material to be extruded is transported through the wide slot die 2 in the direction of the arrow 13 in the direction of the gap 1. In this case, the gap height is determined by the flexible lip 3, which can be adjusted by the adjusting element 4 at several positions along the wide slot die 2.
[0021] Each adjusting element 4 has a drive 5, here in the form of a stepper motor, which actuates a push rod 6, for example a spindle. The push rod 6 is connected to the two-sided lever 7 by means of a joint 9. The lever 7 is supported on the device by means of a pivot point 12. In this case, the push rod 6 engages the end of the longer lever arm in order to move the latter in the direction towards the drive 5 or away from the drive 5. In the embodiment shown, the lever 7 is configured as an angle lever, wherein the short lever arm is configured as a thickened part of the entire lever 7 and extends from its direction of action substantially perpendicularly to the direction of action of the first lever arm. Near the end of the short second lever arm, it contacts the pressure pin 8. If the lever 7 is pulled, for example, in the direction of the drive 5 by the push rod 6, the second short lever arm presses the pressure pin 8 downwards on the flexible lip 3, and the gap 1 of the wide slot die 2 is thus narrowed in this area. Firstly, since the point of action of the pressure pin on the short lever arm must exert significantly greater force to move the first lever arm, and secondly, since the push rod 6 configured as a spindle prevents an undesired movement in the axial direction of the drive 5, an automatic reset is prevented.
[0022] Figure 2 Schematically, four adjusting elements 4 are shown next to each other on a wide slot die 2. The adjusting elements 4 are arranged in two rows 10, 11, as a result of which they can be arranged very closely side by side. In each case, the adjusting elements 4 of the rear row 10 are alternately located next to the adjusting elements 4 of the front row 11. Due to the design of the adjusting elements 4, which must exert a small driving force via a relatively long but compactly mounted lever 7 to adjust the pressure pin 8 and thus the flexible lip 3, it is also possible to use cheaper, weaker and therefore smaller motors than the drive 5, which is not possible in the case of designs with directly driven adjusting screws or transmissions.
[0023] Figure 3A detailed section of the adjusting device in the front region of the wide slot die 2 is shown. Only the upper part of the wide slot die 2 with the flexible lip 3 is shown. The adjusting device is supported on the wide slot die 2 in a correspondingly provided support 16 via the webs 15 of the connecting element 14. Between the webs 15 there is a recess 17 in the connecting element 14 which allows air to pass through. The contact points between the wide slot die 2 and the connecting element 14 are therefore limited to this supporting region, as a result of which a small amount of direct heat transfer from the wide slot die 2 to the connecting element 14 and thus to the adjusting device is possible. Furthermore, the pressure pin 8 has rounded ends at both ends, as a result of which the contact points between the flexible lip 3 which usually has its own heating device and the pressure pin 8 or between the pressure pin 8 and the lever 7 are also minimized here. Therefore, a direct heat transfer is also almost impossible here, which saves energy and improves the product quality of the extruded film.
Claims
1. A device for adjusting the gap (1) of a wide slot die (2) for producing a flat web extruded product such as a film, in, The wide slot die (2) has a flexible lip (3) and a plurality of adjustment elements (4) are arranged at regular intervals along its length for adjusting the gap profile of the lip (3), characterized in that each adjustment element (4) comprises a drive (5), preferably in the form of a stepper motor, wherein the drive (5) actuates a push rod (6) which is hingedly connected to the long arms of two side levers (7), and wherein the short arms of the levers (7) cooperate with linearly guided pressure pins (8) which in turn act on the flexible lip (3) so as to adjust the gap (1) in the area.
2. The device for adjusting the gap (1) of the wide slot die (2) according to claim 1, It is characterized in that The push rod (6) is a main shaft with an external thread, which is engaged with an internally threaded bushing that can be rotated by the driver (5) and is connected to the joint (9) on the long arm of the lever (7), or conversely, the main shaft is directly rotatably supported by the driver (5) and is engaged with an internally threaded bushing connected to the joint (9) on the long arm of the lever (7).
3. The device for adjusting the gap (1) of the wide slot die (2) according to claim 1 or 2, It is characterized in that The two-side lever (7) is an angle lever, wherein the long arm of the lever (7) is arranged in substantially the same longitudinal direction as the pressure pin (8), and the short arm of the lever (7) extends substantially perpendicular to the longitudinal direction of the pressure pin (8).
4. A device for adjusting the gap (1) of a wide slot die (2) according to any one of claims 1 to 3, It is characterized in that The adjustment elements (4) are arranged along the wide slot die (2) in the region of the pressure pin (8) at a distance of approximately 2 cm to 3 cm, preferably approximately 2.5 cm, from one another.
5. A device for adjusting the gap (1) of a wide slot die (2) according to any one of claims 1 to 4, It is characterized in that In the region of the drive (5), the adjusting elements (4) are arranged in two rows (10, 11) extending parallel to the wide slot die (2), so that the adjusting elements (4) of one row (10) and the adjusting elements (4) of the other row (11) are alternately adjacent to each other.
6. A device for adjusting the gap (1) of a wide slot die (2) according to any one of claims 1 to 5, It is characterized in that The pressure pin (8) is guided for linear movement in a connecting element (14), wherein the connecting element (14) is used to connect the device to the wide slot die (2), and wherein the connecting element (14) can be supported in corresponding seats (16) on the wide slot die (2) via two webs (15).
7. A device for adjusting the gap (1) of a wide slot die (2) according to any one of claims 1 to 6, It is characterized in that The pressure pin (8) tapers or is rounded at both ends so that the contact points between the flexible lip (3) of the wide slot die (2) and the pressure pin (8) and between the pressure pin (8) and the two side levers (7) are as small as possible or almost point-like, with the result that only slight direct heat transfer is possible between these components.
8. A device for adjusting the gap (1) of a wide slot die (2) according to any one of claims 1 to 7, It is characterized in that A control unit is provided for all drives (5) of all adjusting elements (4) connected to a wide slot die (2), wherein, based on sensor data about the instantaneous thickness profile of the extruded product and / or based on user input, the control unit brings the individual adjusting elements (4) into the desired position.