Extruder screen changing device suitable for coiled-strip-shaped filter screen

Abstract

An extruder screen changing device suitable for a rolled strip-shaped filter screen comprises a filter head, a screen placing shaft used for placing the rolled filter screen and a screen collecting shaft used for pulling the strip-shaped filter screen, the filter head is provided with a feeding plate block and a discharging plate block, the feeding plate block is provided with a feeding cavity, and the discharging plate block is provided with a discharging cavity. A filter screen supporting plate is arranged between the feeding plate and the discharging plate, a plurality of longitudinal through holes are formed in the transverse middle of the filter screen supporting plate, and no longitudinal through hole is formed in the left side and the right side of the filter screen supporting plate; clamping blocks are arranged on the left side and the right side of the feeding cavity respectively and can be installed in the feeding plate block in a longitudinal sliding mode. The front surface of the left clamping block is close to the rear surface of the left part of the filter screen supporting plate; the front surface of the right clamping block is close to the rear surface of the right part of the filter screen supporting plate; and a pushing and pressing mechanism for applying forward pushing force to the clamping block is further arranged. According to the utility model, the switching between the clamping state and the loosening state of the filter screen can be realized at any accurate time point.

Description

Technical Field

[0001] The utility model belongs to the technical field of plastic extrusion machinery, and in particular relates to an extruder screen changing device suitable for a rolled belt-shaped filter screen. Background Art

[0002] The extruder is used to extrude plastic raw materials to form molten materials and squeeze them into the mold cavity of the plastic mold. Since the plastic raw materials contain granular impurities, the extruder needs to be equipped with a filter. After a period of use, the filter will accumulate impurities and need to be replaced. Early filters were sheet-shaped; every time a filter was replaced, the machine needed to be stopped and the filter removed and then replaced with a new one, which resulted in the inability to discharge materials continuously, long downtime, and inconvenience in use.

[0003] Later, people designed an extruder screen changing device suitable for rolled filter screens, which includes a filter head, a screen-releasing shaft for placing the rolled filter screen, and a screen-collecting shaft for pulling the filter screen strip, the screen-releasing shaft and the screen-collecting shaft are respectively located on the two lateral sides of the filter head; the filter head is provided with a feed chamber and a discharge chamber, and a filter screen support plate is provided between the feed chamber and the discharge chamber, and a plurality of longitudinal through holes for the molten plastic material to flow through are provided in the lateral middle part of the filter screen support plate, and the filter screen support plate is used to provide backward support force to the filter screen. During the production process, the unused filter is rolled up and placed on the net-releasing shaft. After the roll filter is unrolled, it becomes a strip filter (roll and strip are different forms of the filter before and after unrolling, so this filter is called a roll strip filter to distinguish it from the traditional sheet filter). The strip filter passes through the feed cavity and rests against the back of the filter support plate. The used filter is collected by the collection shaft. After the molten plastic material comes out of the extruder, it flows into the feed cavity, is filtered by the filter, flows through the longitudinal through holes of the filter support plate, and then flows into the discharge cavity. Finally, it flows out of the filter head from the discharge cavity and flows into the mold cavity of the mold. When the filter needs to be replaced, just rotate the collection shaft to a certain angle to drive the strip filter inside the filter head to move horizontally for a certain distance.

[0004] In the above structure, in order to prevent the molten material from leaking out from the left and right sides of the feed cavity during the extrusion process, the filter screen must be tightly closed before it enters the feed cavity and after it passes out of the feed cavity; but on the other hand, when the filter screen is pulled during the screen changing process, the filter screen cannot be clamped, otherwise the filter screen cannot be pulled horizontally. In order to solve this contradiction, the technical solution adopted by the Chinese patent document CN208359432 U is to set a cooling water pipeline and a heater inside the filter head; in this way, during the extrusion process, the cooling water pipeline can be used to cool down the nearby parts on the left and right sides of the mesh belt channel, so that the plastic materials near the left and right sides of the mesh belt channel solidify, thereby preventing the molten material from leaking out from the left and right sides of the mesh belt channel; and when the mesh needs to be changed, the heater can be used to heat up the nearby parts on the left and right sides of the mesh belt channel, so that the plastic materials near the left and right sides of the mesh belt channel melt, and the filter screen can be pulled horizontally at this time. Chinese patent documents such as CN203110306U, CN218286656U5, CN203110306U, and CN201816212U also adopt a similar structure. However, the above structure has the following problems:

[0005] 1. Since it takes a while for plastic to melt or solidify, and the melting points and solidification points of plastics of various materials vary greatly, it is difficult to control at a precise time point and ensure that the plastic melts or solidifies. If the extruder starts to extrude before the plastic solidifies, there is a risk of leakage; if the net is pulled before the plastic melts after shutdown, the filter cannot be pulled and the shutdown time needs to be extended.

[0006] Second, the left and right sides of the mesh belt channel are closed by solidified plastic material. However, the maximum extrusion pressure of the extruder is limited due to the limited pressure that the plastic solidified next to the cooling water pipe can withstand. Generally, the extrusion pressure cannot exceed 10 MPa. Moreover, the maximum extrusion pressure that can be sustained is also limited by the plastic material. If the material of the plastic material is poor, the extrusion pressure that can be sustained may be much lower than 10 MPa. Low extrusion pressure further leads to low flow and low output. Utility Model Content

[0007] The purpose of the utility model is to overcome the above-mentioned shortcomings and provide an extruder screen changing device suitable for a rolled belt filter screen, which can realize the conversion of the filter screen clamping state and the filter screen loose state at any precise time point, and the conversion of the filter screen clamping state and the filter screen loose state can be completed in an instant, making the screen change easier and saving time.

[0008] The purpose can be achieved according to the following scheme: an extruder screen changing device suitable for a rolled strip filter screen, comprising a filter head, a screen placing shaft for placing the rolled strip filter screen, and a screen collecting shaft for pulling the strip filter screen, the filter head is provided with a feed plate and a discharge plate, the feed plate is provided with a feed cavity, the discharge plate is provided with a discharge cavity, the discharge cavity is located in front of the feed cavity, a filter screen support plate is provided between the feed plate and the discharge plate, a plurality of longitudinal through holes for molten plastic material to flow through are provided in the transverse middle part of the filter screen support plate, the longitudinal through holes are located between the feed cavity and the discharge cavity, and no longitudinal through holes are provided in the left and right side parts of the filter screen support plate; it is characterized in that: clamping blocks are respectively provided on the left and right sides of the feed cavity, and the clamping blocks can be longitudinally slidably installed in the feed plate; the front surface of the left clamping block is close to the rear surface of the left side part of the filter screen support plate, and the front surface of the right clamping block is close to the rear surface of the right side part of the filter screen support plate; a pushing mechanism is also provided to apply a forward thrust to the clamping block.

[0009] Each clamping block is provided with a long hole, which is oriented vertically; an eccentric roller is rotatably installed inside the filter head, the number of eccentric rollers is equal to the number of clamping blocks, the axial direction of the eccentric roller is vertical, each eccentric roller passes through the long hole of a corresponding clamping block, the longitudinal dimension of the long hole cavity is equal to the diameter of the eccentric roller, and the transverse dimension of the long hole cavity is larger than the diameter of the eccentric roller; an eccentric roller driving mechanism is also provided to drive the eccentric roller to rotate; the eccentric roller driving mechanism and the eccentric roller form the pushing mechanism.

[0010] The eccentric roller driving mechanism may be a hydraulic motor.

[0011] The eccentric roller driving mechanism may also be a motor.

[0012] A central controller and an encoder for detecting the rotation angle of the eccentric roller are also provided. The encoder is connected to the central controller, and the central controller is connected to the eccentric roller driving mechanism.

[0013] A slanted block is also provided behind the clamping block, and the slanted block can be installed in the filter head in a vertical sliding manner; the contact surfaces of the clamping block and the slanted block are inclined surfaces and the two can slide relative to each other; a vertical oil cylinder is also provided, and the piston rod of the vertical oil cylinder drives the connected slanted block; the vertical oil cylinder and the slanted block form the pushing mechanism.

[0014] A central controller and a displacement detector for detecting the moving position of the inclined block are also provided. The displacement detector is connected to the central controller, and the central controller is connected to the vertical oil cylinder.

[0015] Among the two components of the clamping block and the inclined block, one component is provided with a clamping groove, and the other component is provided with a convex rib, the maximum width of the convex rib is greater than the notch width of the clamping groove, and the convex rib can be slidably inserted into the clamping groove.

[0016] The cross section of the convex rib is T-shaped, and the groove cavity of the clamping groove is correspondingly T-shaped.

[0017] The utility model has the following advantages and effects:

[0018] 1. During the extrusion process, the pushing mechanism presses the clamp forward, so that the front surface of the clamp and the rear surface of the two sides of the filter support plate clamp the filter, so as to prevent the molten material from leaking out from the left and right sides of the feed cavity. When the screen needs to be changed, the pushing mechanism no longer presses the clamp forward, that is, the clamp and the two sides of the filter support plate no longer clamp the filter. At this time, the filter can be easily pulled horizontally by rotating the screen collection shaft, and the screen can be easily changed.

[0019] Second, the utility model can realize the conversion of the filter screen between the clamping state and the loosening state at any precise time point, and the conversion of the filter screen between the clamping state and the loosening state can be completed in an instant, making the screen replacement easier and saving more time.

[0020] 3. The filter head can withstand high extrusion pressure and is not affected by the material. In practice, it can withstand a pressure of about 25 MPa. The high extrusion pressure further achieves high flow rate and high output. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a three-dimensional structural schematic diagram of the first specific embodiment of the utility model.

[0022] Figure 2 yes Figure 1 Front view of the structure shown.

[0023] Figure 3 yes Figure 2 Middle AA section view.

[0024] Figure 4 yes Figure 3 A partial enlarged schematic diagram of the filter head.

[0025] Figure 5 yes Figure 4 Schematic diagram of the structure of the middle filter support plate.

[0026] Figure 6 It is a structural schematic diagram of an eccentric roller.

[0027] Figure 7 yes Figure 4 Schematic diagram of the matching relationship between the eccentric roller and the clamping block.

[0028] Figure 8 yes Figure 3 Middle BB section view.

[0029] Fig. 9 yes Figure 8 A partial enlarged schematic diagram.

[0030] Fig.10 yes Figure 3 Middle CC section view.

[0031] Fig.11 yes Figure 4 Schematic diagram of the changing state of the structure shown when changing the screen.

[0032] Fig.12 It is a schematic diagram of the horizontal cross-section structure of the filter head of the second specific embodiment of the utility model.

[0033] Fig.13 yes Fig.12 Middle KK cross-section.

[0034] Fig.14 yes Fig.12 Schematic diagram of the exploded view of the center clamp and the oblique block. DETAILED DESCRIPTION Embodiment 1

[0035] Figure 1 , Figure 2 , Figure 3 , Figure 8 , Fig. 9 As shown, the extruder screen changing device adapted for the rolled-belt filter screen comprises a filter head 9, a screen placing shaft 6 for placing the rolled-belt filter screen, and a screen collecting shaft 7 for pulling the filter screen. The filter head 9 is provided with a feed plate 1 and a discharge plate 2. The feed plate 1 is provided with two upper and lower feed channels 10 and two upper and lower feed chambers 11, and each feed channel 10 is connected to a corresponding feed chamber 11; the discharge plate 2 is provided with a discharge channel 20 and a discharge chamber 21, and the discharge chamber 21 is located in front of the upper and lower feed chambers 11, and the discharge chamber 21 is connected to the discharge channel 20, and the discharge channel 20 is connected to a discharge pipe 23, and a filter screen support plate 3 is provided between the feed plate 1 and the discharge plate 2; Figure 4 , Figure 5 , Fig. 9 As shown, a plurality of longitudinal through holes 30 for the molten plastic material to flow through are provided in the transverse middle portion 33 of the filter support plate 3, and the longitudinal through holes 30 are located between the feed cavity 11 and the discharge cavity 21, while no longitudinal through holes are provided in the left portion 31 and the right portion 32 of the filter support plate 3.

[0036] Figure 4 , Figure 6 , Figure 7 , Fig.10As shown, a clamping block 4 is provided on the left and right sides of each upper and lower feed cavity 11, respectively. There are four clamping blocks 4 in the filter head 9, and the upper and lower surfaces of the clamping block 4 are both horizontal planes. The clamping block 4 can be installed in the feed block 1 in a longitudinal sliding manner; the front surface of the left clamping block 4 is close to the rear surface of the left part 31 of the filter support plate, and the front surface of the right clamping block 4 is close to the rear surface of the right part 32 of the filter support plate; a pushing mechanism is also provided to apply a forward thrust to the clamping block 4. Each clamping block 4 is provided with a long hole 41, and the direction of the long hole 41 is vertical; four eccentric rollers 5 are rotatably installed in the filter head 9, and the axial direction of the eccentric roller 5 is vertical. Each eccentric roller 5 passes through the long hole 41 of a corresponding clamping block 4, and the longitudinal dimension of the cavity of the long hole 41 (i.e. Figure 7 The length of the GF is equal to the diameter of the eccentric roller 5, and the transverse dimension of the long hole cavity (i.e. Figure 7 The length of DE in the middle is greater than the diameter of the eccentric roller 5. Since the transverse dimension of the long hole cavity is greater than its longitudinal dimension, it is called a long hole. The eccentric roller 5 is provided with a rotating shaft 50. The geometric center of the cross section of the eccentric roller 5 (at Figure 7 The point M in the figure deviates from the central axis of the rotating shaft 50 (in Figure 7 In the figure, it is represented as point N), and a hydraulic motor 51 is provided to drive the eccentric roller 5 to rotate around the central axis of the rotating shaft 50. There are four hydraulic motors 51 corresponding to the four eccentric rollers 5; the hydraulic motor 51 and the eccentric roller 5 form the pushing mechanism. A central controller and an encoder for detecting the rotation angle of the eccentric roller are also provided. The encoder is connected to the central controller, and the central controller is connected to the hydraulic motor 51.

[0037] When the above-mentioned embodiment 1 is working, the extrusion port of the extruder is connected to the feed channel 10 of the filter head 9, and the discharge channel 20 of the filter head 9 is connected to the mold cavity of the mold through the discharge pipe 23; the unused rolled filter screen 81 is placed on the screen placing shaft 6, and the rolled filter screen 81 becomes a strip filter screen 8 after being unwound; the filter screen is divided into two groups, the upper group of strip filter screens 8 enters the upper feed cavity 11, and the lower group of strip filter screens 8 enters the lower feed cavity 11; the strip filter screen 8 is attached to the back of the central part 33 of the filter screen support plate, and passes between the clamping block 4 and the left part 31 of the filter screen support plate, and also passes between the clamping block 4 and the right part 32 of the filter screen support plate. The discarded filter screen is wound and collected by the screen collecting shaft 7, as shown in FIG. Figure 1 , Figure 2 , Figure 3 , Figure 4 When the molten material is extruded, the hydraulic motor 51 applies torque to the eccentric roller 5, and the eccentric roller 5 acts as a cam, exerting a forward thrust on the clamping block 4. The clamping block 4 and the left and right sides of the filter support plate clamp the belt filter 8, so that the molten material can be prevented from leaking out from the left and right sides of the feed cavity 11. Fig.10 , Figure 4As shown. When the extrusion pressure fluctuates and causes the clamp block 4 to move longitudinally, the eccentric roller 5 rotates. The encoder can detect this change and notify the central controller. The central controller commands the hydraulic motor 51 to increase the pressure to push the eccentric roller 5 and the clamp block 4 back to the normal working position. When the screen needs to be changed, the hydraulic motor 51 drives the eccentric roller 5 to rotate, so that the eccentric roller 5 pushes the clamp block 4 backward, and the clamp block 4 no longer presses the belt filter 8 tightly, as shown. Fig.11 As shown, the net collecting shaft 7 can pull the belt-shaped filter screen 8 to move horizontally, and the rolled filter screen 81 on the net releasing shaft 6 is unwound for a certain length to complete the net changing.

[0038] In the above-mentioned first embodiment, the hydraulic motor 51 may also be replaced by an electric motor. Embodiment 2

[0039] The main difference between the second embodiment and the first embodiment is that the pushing mechanism of each clamping block 4 in the second embodiment is a vertical oil cylinder 53 and an inclined block 52, wherein the inclined block 52 is arranged behind the corresponding clamping block 4, and the inclined block 52 can be vertically slidably installed in the filter head 9, such as Fig.12 , Fig.13 The contact surfaces of the clamp block 4 and the inclined block 52 are inclined surfaces, and the clamp block 4 and the inclined block 52 can slide relative to each other (ie, slide relative to each other along the contact surfaces of the two), and the piston rod of the vertical cylinder 53 drives the inclined block 52 to connect. Fig.12 , Fig.14 As shown, the clamping block 4 is provided with a clamping groove 40, and the inclined block 52 is provided with a convex rib 520. The cross section of the convex rib 520 is T-shaped, and the groove cavity of the clamping groove 40 is T-shaped. The maximum width of the convex rib 520 ( Fig.14 The dimension line m in the figure is greater than the slot width of the clip groove 40 ( Fig.14 The rib 520 can be slidably inserted into the clamping groove 40. A central controller and a displacement detector for detecting the vertical movement position of the inclined block 52 are also provided. The displacement detector is connected to the central controller, and the central controller is connected to the vertical oil cylinder 53.

[0040] The remaining structures of the second embodiment are the same as those of the first embodiment.

[0041] During use of the second embodiment, the belt filter 8 is attached to the back of the central part 33 of the filter support plate, and passes between the clamp block 4 and the left part 31 of the filter support plate, and also passes between the clamp block 4 and the right part 32 of the filter support plate. The discarded filter is collected by the net collection shaft 7. When the molten material is extruded, the vertical cylinder 53 applies vertical pressure to the inclined block 52. The inclined block 52 presses the clamp block 4 forward through the action of the inclined surface. The clamp block 4 and the left and right parts of the filter support plate clamp the belt filter 8, so that the molten material can be prevented from leaking from the left and right sides of the feed cavity 11. When the extrusion pressure fluctuates and causes the clamp block 4 to move in the longitudinal position, the inclined block 52 moves vertically, and the amplitude of the vertical movement of the inclined block 52 is multiple times the amplitude of the longitudinal movement of the clamp block 4. The displacement detector can detect this fluctuation sensitively and notify the central controller. The central controller commands the vertical cylinder to increase the pressure to push the inclined block 52 and the clamp block 4 back to the normal working position. When the screen needs to be changed, the piston rod of the vertical oil cylinder 53 contracts, the inclined block 52 moves vertically, the clamping block 4 retreats, and the clamping block 4 no longer presses the filter screen 8, so the screen collecting shaft 7 can pull the belt filter screen 8 to move horizontally to implement the screen change.

[0042] In the above-mentioned second embodiment, the groove cavity of the clamping groove 40 can be changed into a dovetail groove, and accordingly, the cross section of the convex rib 520 can be changed into a dovetail shape.

Claims

1. An extruder screen changing device adapted for a rolled-up filter screen, comprising a filter head, a screen placing shaft for placing the rolled-up filter screen, and a screen collecting shaft for pulling the rolled-up filter screen, the filter head is provided with a feed plate and a discharge plate, the feed plate is provided with a feed cavity, the discharge plate is provided with a discharge cavity, the discharge cavity is located in front of the feed cavity, a filter screen support plate is provided between the feed plate and the discharge plate, a plurality of longitudinal through holes for molten plastic materials to flow through are provided in the transverse middle part of the filter screen support plate, the longitudinal through holes are located between the feed cavity and the discharge cavity, and no longitudinal through holes are provided on the left and right sides of the filter screen support plate; the characteristics are as follows: Clamping blocks are respectively provided on the left and right sides of the feed chamber, and the clamping blocks can be longitudinally slidably installed in the feed plate; the front surface of the left clamping block is close to the rear surface of the left part of the filter support plate, and the front surface of the right clamping block is close to the rear surface of the right part of the filter support plate; a pushing mechanism is also provided to apply forward thrust to the clamping block.

2. The extruder screen changing device adapted for a rolled belt filter screen according to claim 1, characterized in that: Each clamping block is provided with a long hole, which is oriented vertically; an eccentric roller is rotatably installed inside the filter head, the number of eccentric rollers is equal to the number of clamping blocks, the axial direction of the eccentric roller is vertical, each eccentric roller passes through the long hole of a corresponding clamping block, the longitudinal dimension of the long hole cavity is equal to the diameter of the eccentric roller, and the transverse dimension of the long hole cavity is larger than the diameter of the eccentric roller; an eccentric roller driving mechanism is also provided to drive the eccentric roller to rotate; the eccentric roller driving mechanism and the eccentric roller form the pushing mechanism.

3. The extruder screen changing device adapted for a rolled belt filter screen according to claim 2, characterized in that: The eccentric roller driving mechanism is a hydraulic motor.

4. The extruder screen changing device adapted for a rolled belt filter screen according to claim 2, characterized in that: The eccentric roller driving mechanism is a motor.

5. The extruder screen changing device adapted for a rolled belt filter screen according to claim 2, 3 or 4, characterized in that: A central controller and an encoder for detecting the rotation angle of the eccentric roller are also provided. The encoder is connected to the central controller, and the central controller is connected to the eccentric roller driving mechanism.

6. The extruder screen changing device adapted for a rolled belt filter screen according to claim 1, characterized in that: A slanted block is also provided behind the clamping block, and the slanted block can be installed inside the filter head in a vertical sliding manner; the contact surfaces of the clamping block and the slanted block are inclined surfaces and the two can slide relative to each other; a vertical oil cylinder is also provided, and the piston rod of the vertical oil cylinder drives the connected slanted block; the vertical oil cylinder and the slanted block form the pushing mechanism.

7. The extruder screen changing device adapted for a rolled belt filter screen according to claim 6, characterized in that: A central controller and a displacement detector for detecting the moving position of the inclined block are also provided. The displacement detector is connected to the central controller, and the central controller is connected to the vertical oil cylinder.

8. The extruder screen changing device adapted for a rolled belt filter screen according to claim 6 or 7, characterized in that: Among the two components of the clamping block and the inclined block, one component is provided with a clamping groove, and the other component is provided with a convex rib, the maximum width of the convex rib is greater than the notch width of the clamping groove, and the convex rib can be slidably inserted into the clamping groove.

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