Compact type screen changing device applied to ultra-large type extrusion granulating unit and using method of compact type screen changing device

Abstract

The invention belongs to the technical field of melt filtering screen changing devices, and discloses a compact screen changing device applied to an ultra-large type extrusion granulating unit and a using method. The device is mainly composed of a screen changing shell, a sliding column, a sealing water jacket and a filter screen. Two axial through holes are formed in the screen changing shell, sliding columns are installed in the through holes, and filter screens are installed in the sliding columns. Sealing water jackets are installed at the left end and the right end of the screen changing shell, and melt self-sealing is achieved. The front side and the rear side of the screen changing shell are provided with a feeding inclined flow channel and a discharging straight flow channel, and the flow channels are communicated with the hollowed-out parts of the upper sliding column and the lower sliding column respectively. Wherein the plane of the discharging runner is parallel to the left and right end faces, and the left and right end faces of the plane of the feeding runner form a certain angle. The inclined feeding design is adopted for the shell of the screen changing device, so that the structure of the screen changing device is more compact compared with a conventional screen changing device, the occupied space is reduced, the stroke of the sliding column is shortened, and the screen changing efficiency is improved. Meanwhile, under the same specification, the weight of the screen changing shell and the sliding column is reduced, and the cost is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of melt filtration screen changing devices, and particularly to a compact screen changing device applied to an ultra-large extrusion granulation unit and a usage method thereof. Background Art

[0002] In the field of plastic processing, extrusion granulation is the most important processing method. Since plastic raw materials generally contain various impurities, if these impurities directly participate in the extrusion process without being treated, it will seriously affect the quality and performance of the final product. Therefore, a filtering device is installed at the front end of the extruder to effectively remove impurities in the raw materials and ensure that the quality of the extruded granulation product meets the standards. With the continuous development of plastic extrusion equipment towards large-scale, high-yield, and high-efficiency directions, the overall specifications of the equipment have also increased significantly. Although this trend has improved production efficiency, it has also brought new problems: the increase in the volume and weight of the equipment has led to an increase in manufacturing costs, an expansion of the floor area, and a significant increase in energy consumption. In addition, when replacing the filter screen of the filtering device in an ultra-large equipment, due to the complex operation and long time consumption, it seriously affects the continuity and efficiency of the production line.

[0003] In the design of conventional-sized screen changing devices, the straight-through channel structure is widely used. However, when this design is applied to ultra-large granulation equipment, there will be obvious redundancy problems. It not only increases the volume and weight of the screen changing device, but also leads to an increase in design costs and an expansion of the floor area. More seriously, during the screen changing process, since the sliding column needs to move a large stroke, it not only significantly reduces the screen changing efficiency, but also increases the operation difficulty and the risk of failure. Summary of the Invention

[0004] The purpose of the present invention is to provide a compact screen changing device applied to an ultra-large extrusion granulation unit and a usage method thereof, aiming to improve product output, achieve a compact structure through optimized design, reduce material costs and floor area, and thus promote the sustainable development of the plastic processing industry.

[0005] The technical solution adopted by the present invention to achieve the above purpose is: a compact screen changing device applied to an ultra-large extrusion granulation unit, including a screen changing housing 1, a sliding column 2, a sealing water jacket 3, and a filter screen 4;

[0006] Two sealing water jackets 3 are respectively installed at the left and right ends of the screen changing housing 1, and the screen changing housing 1 is provided with two through holes; the sliding column 2 is installed in the through holes, and the sliding column 2 slides in the through holes; a part of the middle of the sliding column 2 is hollowed out, and the filter screen 4 is installed at the hollowed-out position; a feed flow channel and a discharge flow channel are respectively opened on the front side and the rear side of the screen changing housing 1, and are respectively communicated with the hollowed-out part of the sliding column 2; the feed flow channel is inclined, and the discharge flow channel is straight.

[0007] The plane where the feeding inclined runner of the screen-changing housing 1 is located forms a certain angle with the axial plane of the sliding column 2, which is used to reduce the volume of the housing and the length of the sliding column.

[0008] The range of the inclined angle is limited by the axial width of the hollowed-out part. On the basis that the inclined angle cannot exceed the space limit of the structure of the hollowed-out part, the inclined angle takes the largest possible value within the allowable range; the structure of the hollowed-out part is determined by the material output and the pressure difference of the filter screen 4; at the same time, the hollowed-out part also needs to ensure that the shear rate of the material during flow is greater than 8 s -1 , and the shear stress of the wall surface of the screen-changing housing 1 in contact with the material is less than 140 KPa.

[0009] A method of using a compact screen-changing device applied to an ultra-large extrusion granulation unit. When replacing the filter screen 4, stop feeding cooling water into the sealing water jacket 3, push one of the sliding columns 2 out to one end to expose the filter screen 4, and replace the filter screen 4; pull back the originally pushed-out sliding column 2 to the exhaust position at the other end to discharge the air in its hollowed-out part; after exhausting, adjust the sliding column 2 back to the working position; repeat the above operations for the other sliding column 2; finally, feed cooling water into the sealing water jacket 3 to restore the normal working state.

[0010] During the process of pushing out and pulling back the sliding column 2, it is necessary to ensure that the hollowed-out part of the sliding column 2 remains in a relatively closed state.

[0011] The relatively closed state is: during the process of pushing out the sliding column 2, the hollowed-out part of the sliding column 2 just leaves the inlet of the screen-changing device, and at this time the other end of the hollowed-out part has not left the sealing water jacket 3, so that the hollowed-out part is in a relatively closed state.

[0012] The beneficial effects of the present invention:

[0013] (1) Compact structure and lower material cost;

[0014] (2) Short stroke of the sliding column and high screen-changing speed;

[0015] (3) The volumes of the housing and the sliding column are smaller than those of the conventional screen-changing device of the same specification, and the floor area is reduced. Description of the Drawings

[0016] Figure 1 It is a schematic structural diagram of a compact screen-changing device applied to an ultra-large extrusion granulation unit;

[0017] Figure 2 It is a cross-sectional view of the structure of a compact screen-changing device applied to an ultra-large extrusion granulation unit;

[0018] Figure 3 It is a comparison schematic diagram of the relative closed position of the hollowed-out part of the sliding column between the screen-changing device of the present invention and the conventional screen-changing device. Detailed Embodiments

[0019] The present invention designs a compact screen changer device applied to an ultra-large extrusion granulation unit, which involves a screen changer housing 1, sliding columns 2, a sealing water jacket 3, and a filter screen 4. There are two axial through holes on the screen changer housing 1, and sliding columns 2 are installed in the axial through holes. The two sliding columns 2 are arranged vertically; the sliding columns 2 are provided with hollowed-out parts, and a filter screen 4 is installed on the hollowed-out parts. An inclined feed channel and a straight discharge channel are respectively opened on the front and rear sides of the screen changer housing 1. The two channels communicate with the hollowed-out parts of the two vertically arranged sliding columns 2. Sealing water jackets are installed at both ends of the screen changer housing 1 to ensure the sealing performance of the device.

[0020] The plane where the inclined feed channel of the screen changer housing 1 is located forms a certain angle with the axial plane of the sliding column 2.

[0021] As Figure 1 The compact screen changer device applied to an ultra-large extrusion granulation unit as shown mainly consists of a screen changer housing 1, sliding columns 2, a sealing water jacket 3, and a filter screen 4. There are two axial through holes on the screen changer housing 1, and sliding columns 2 are installed in the through holes. A filter screen is installed in the hollowed-out part of the sliding column 2. Sealing water jackets 3 are installed at the left and right ends of the screen changer housing 1 to achieve self-sealing of the melt. The screen changer housing 1 is provided with a feed channel and a discharge channel on the front and rear sides. The plane where the discharge channel is located is perpendicular to the axial plane of the sliding column, while the plane where the feed channel is located forms a certain angle with the axial plane of the sliding column. The feed channel and the discharge channel respectively communicate with the hollowed-out parts of the upper and lower sliding columns 2.

[0022] When the present screen changer device is in the working state, the molten material is branched through the feed channel and enters the hollowed-out parts of the upper and lower two sliding columns 2 through two branch channels respectively. The material then passes through the filter screen 4, flows into the discharge channel, and is finally discharged from the discharge port. As the impurities on the filter screen in the hollowed-out part gradually increase and the pressure difference between the inlet and outlet reaches a certain set value, the screen changer device needs to replace the filter screen.

[0023] During the process of replacing the filter screen, first, the production output needs to be appropriately reduced to ensure operation safety. Subsequently, stop supplying cooling water to the sealing water jacket 3, push the upper sliding column to the right to expose the filter screen 4, and replace the filter screen 4. Then, pull the upper sliding column back to the left to the exhaust position to discharge the air in the hollowed-out part of the sliding column 2. After exhausting, the upper sliding column 2 is readjusted to the working position, and the lower sliding column repeats the operation of the upper sliding column. Finally, supply cooling water to the sealing water jacket 3 to make the screen changer device return to the normal working state.

[0024] It should be particularly noted that during the process of pushing out and pulling back the sliding column 2, it is necessary to ensure that the hollowed-out part of the sliding column 2 remains in a relatively closed state ( Figure 3 ). The purpose of doing this is to prevent the material at the feed port from communicating with the atmospheric environment through the hollowed-out part, thereby avoiding the material directly flowing out through the hollowed-out part into the atmosphere, resulting in waste of the material and threatening the safety of personnel.

[0025] The present invention has significant features compared with similar products: Since the feeding port on the screen changing housing 1 of the present invention adopts an inclined feeding channel, this design can effectively reduce the stroke of the slide column and make the housing structure more compact. Figure 3 It can be seen that compared with the screen changing device that conventionally adopts a straight feeding channel structure, the inclined feeding channel of the present invention effectively reduces the use of redundant materials. In a large-scale screen changing device, this improvement can significantly improve the space utilization rate and reduce the material cost.

Claims

1. A compact screen changer applied to an extra-large extrusion granulation unit, characterized in that It includes a screen-changing housing (1), a slide post (2), a sealing water jacket (3) and a filter screen (4). Two sealing water jackets (3) are installed at each of the left and right ends of the screen-changing housing (1). The screen-changing housing (1) is provided with two through holes. The slide posts (2) are installed in the through holes and slide in the through holes. A part of the middle of the slide posts (2) is hollowed out, and the filter screen (4) is installed at the hollowed-out position. An inlet flow channel and an outlet flow channel are respectively formed on the front side and the rear side of the screen-changing housing (1), and are respectively communicated with the hollowed-out part of the slide posts (2). The inlet flow channel is inclined, and the outlet flow channel is straight.

2. The compact screen changer applied to an extra-large extrusion granulation unit according to claim 1, characterized in that, The plane where the inclined inlet flow channel of the screen-changing housing (1) is located forms a certain angle with the axial plane of the slide posts (2), which is used to reduce the volume of the housing and the length of the slide posts.

3. The compact screen changer applied to an extra-large extrusion granulation unit according to claim 2, wherein The bevel angle range is limited by the axial width of the hollowed-out part. On the basis that the bevel angle cannot exceed the spatial boundary of the structure of the hollowed-out part, the bevel angle takes the largest possible value within the allowable range; the structure of the hollowed-out part is determined by the material output and the pressure difference of the filter screen (4); at the same time, the hollowed-out part also needs to ensure that the shear rate of the material during flow is greater than 8 s -1 , and the shear stress on the wall surface of the screen-changing housing (1) in contact with the material is less than 140 KPa.

4. A method for using the compact screen changer device applied to an extra-large extrusion granulation unit according to any one of claims 1-3, characterized in that, When replacing the filter screen (4), stop supplying cooling water to the sealing water jacket (3), push out one of the slide posts (2) at one end to expose the filter screen (4), and replace the filter screen (4). Pull back the originally pushed-out slide post (2) to the exhaust position at the other end to discharge the air in its hollowed-out part. After exhausting, adjust the slide post (2) back to the working position. Repeat the above operations for the other slide post (2). Finally, supply cooling water to the sealing water jacket (3) to restore the normal working state.

5. The usage method according to claim 4, characterized in that, During the process of pushing out and pulling back the slide posts (2), it is necessary to ensure that the hollowed-out part of the slide posts (2) remains in a relatively closed state.

6. The usage method according to claim 5, wherein The relatively closed state is: during the process of pushing out the slide posts (2), the hollowed-out part of the slide posts (2) just leaves the inlet of the screen-changing device. At this time, the other end of the hollowed-out part has not left the sealing water jacket (3), so that the hollowed-out part is in a relatively closed state.

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