Vacuum cleaning equipment for screw extruder

Abstract

The utility model relates to the technical field of extrusion molding, in particular to vacuum cleaning equipment for a screw extruder. The end face of the cleaning piston comprises a first end face area and a second end face area which are arranged in the radial direction of the screw. The first end face area inclines relative to the axis of the piston rod, and the inclination direction is matched with the circumferential inclination direction of the outer circumferential face of the screw below the first end face area. The second end face area is connected to the side, transversely away from the axis of the piston rod, of the first end face area and extends in the direction away from the screw below the second end face area relative to the first end face area. According to the shape design of the first end face area and the second end face area formed by the cleaning piston, the screw rod can extend into the vacuum hole as deep as possible under the condition that work of the screw rod is not affected, the hole opening position and the hole wall of the vacuum hole can be better cleaned, and therefore raw material pollution can be further prevented, production continuity is improved, manual intervention is reduced, and production efficiency is improved. And the cost is saved while the product quality is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to extrusion molding technical field especially relates to a vacuum cleaning equipment for screw extruder. BACKGROUND

[0002] Screw extruder is widely used in the production of plastic products, for example, used to extrude plastic board in floor production line. Generally speaking, screw extruder includes barrel and at least two screws in the barrel, the front end of the barrel is provided with a head, and the raw material in the barrel is extruded into a board through the head. Among them, the raw material in the barrel will appear different degrees of gasification, decomposition and precipitation under high temperature, thereby generating a large amount of hot steam and precipitate and other low molecular substances, and when these low molecular substances cannot be well released, they will be mixed in the extruded board, resulting in the performance of the board being reduced.

[0003] At present, in order to effectively promote the low molecular substances to be discharged from the barrel without entering the board, a vacuum device is installed on the barrel, and the low molecular substances are separated and discharged from the molten raw material through the vacuum device. The vacuum device generally includes a vacuum box fixed on the barrel, and a vacuum hole communicating with the inner cavity of the barrel is arranged on the barrel, and then the low molecular substances in the barrel are sucked into the vacuum box through the vacuum hole, and further transported to the outside of the equipment.

[0004] The problem that follows is that after working for a period of time, the low molecular substances are accumulated and adhered to the inner wall of the vacuum hole, causing the vacuum hole to be blocked. On the one hand, the gradual reduction of the vacuum suction efficiency will lead to the increase of the residual hot steam and precipitate in the raw material, and on the other hand, the color of the accumulated substances gradually turns black over time, and these black substances will fall into the raw material in the barrel when the extruder vibrates frequently, which will all lead to the decline of product quality.

[0005] Therefore, the production personnel must regularly stop and clean the vacuum hole and the vacuum box, which reduces the production efficiency. Based on the above problems, the production personnel further installs a cleaning device on the vacuum box, and the cleaning device includes two piston rods and two cylindrical cleaning pistons to adapt to the vacuum hole on the barrel, and the two piston rods can drive the two cylindrical cleaning pistons to extend into the vacuum hole for reciprocating cleaning work. However, there is still the problem that the cleaning effect is not ideal and the adhering substances in the vacuum hole will still fall into the raw material and pollute the raw material. UTILITY MODEL CONTENTS

[0006] (I) Technical problem to be solved

[0007] In view of the above shortcomings and deficiencies of the prior art, the utility model provides a vacuum cleaning equipment for screw extruder to solve the technical problem that the current cleaning effect is not ideal.

[0008] (ii) Technical Solution

[0009] To achieve the above object, the utility model adopts the main technical scheme includes:

[0010] The utility model provides a vacuum cleaning equipment for screw extruder, including piston rod and cleaning piston, piston rod can drive cleaning piston to extend into the vacuum hole of the cylinder of screw extruder and carry out reciprocating cleaning work, the end surface of cleaning piston includes the first end surface area and the second end surface area who links to each other, the arrangement direction of first end surface area and second end surface area is the radial direction of screw, first end surface area is inclined to the axis of piston rod, and the inclined direction is adapted to the circumferential inclined direction of the outer circumferential surface of screw below it, second end surface area is connected in the side of first end surface area transversely away from the axis of piston rod, and second end surface area extends to the direction away from the screw below it relative to first end surface area.

[0011] According to the utility model, the second end surface area is perpendicular to the axis of the piston rod.

[0012] According to the utility model, the ratio of the width of the second end surface area to the length of the vacuum hole is within the range of 1 / 3-1 / 4, and the ratio of the width of the second end surface area to the width of the cleaning piston is less than 1 / 2.

[0013] According to the utility model, the included angle between the first end surface area and the second end surface area is within the range of 150°-180°.

[0014] According to the utility model, the included angle between the first end surface area and the second end surface area is within the range of 160°-170°.

[0015] According to the utility model, the cleaning piston is cylindrical, and the size of the cleaning piston is configured such that an annular gap is formed between the cleaning piston and the inner wall of the vacuum hole when the cleaning piston works in the vacuum hole, and the width of the annular gap is within the range of 1-2mm.

[0016] According to the utility model, the vacuum cleaning equipment further comprises a vacuum box and a vacuum pipe capable of being connected to a negative pressure device, the vacuum box is capable of being installed on the cylinder, the bottom wall of the vacuum box is provided with a feeding hole in communication with the inner cavity thereof, the feeding hole is capable of being in communication with the vacuum hole, the vacuum pipe is connected to one end of the vacuum box, and an air inlet selectively openable to the outside is arranged at the other end of the vacuum box, the air inlet, the inner cavity of the vacuum box and the vacuum pipe are sequentially communicated to form a cold air passage, and the piston rod is capable of driving the cleaning piston to reciprocate in the cold air passage, the feeding hole and the vacuum hole.

[0017] The utility model also includes air inlet pipe, air inlet pipe and vacuum pipe coaxial connection in vacuum box's opposite two ends, be equipped with on-off valve on air inlet pipe to form the air inlet that can select with outside on-off, the end of vacuum pipe away from air inlet pipe is equipped with four branch pipes, the first port in four branch pipes is connected with vacuum pipe, the second port is connected with vacuum gauge, the third port is connected with pressure relief valve, the fourth port is used for connecting negative pressure equipment, on-off valve and pressure relief valve are all manual valve.

[0018] According to the utility model, vacuum cleaning equipment corresponds two vacuum holes and sets up two piston rods, two cleaning pistons and two feeding holes, and the first end face regions of the two cleaning pistons are oppositely arranged, the vacuum cleaning equipment further includes a power source, the power source is fixed on the vacuum box, and the vacuum box can be detachably fixed on the cylinder through bolts, in the case that the axes of the two vacuum holes are parallel, one power source is arranged, and the power output end of the power source is connected with the two piston rods simultaneously, in the case that the axes of the two vacuum holes intersect, two power sources are arranged, and the power output ends of the two power sources are connected with the two piston rods respectively, the piston rod can be coaxially arranged with the vacuum hole, and the power source can drive the cleaning piston to move to the position where the distance between the lowest point and the screw rod is 3-5 mm and stop.

[0019] According to the utility model, the vacuum cleaning equipment is used for the screw extruder in a floor production line, and the end face of the cleaning piston is composed of a first end face region and a second end face region.

[0020] (Three) beneficial effects

[0021] The utility model discloses the beneficial effect is:

[0022] In the vacuum cleaning equipment for the screw extruder of the utility model, the end face of the cleaning piston includes a first end face region and a second end face region connected with each other, the first end face region is inclined relative to the axis of the piston rod, and the inclined direction is adapted to the circumferential inclined direction of the outer peripheral surface of the screw rod below the first end face region, the second end face region is connected to the side of the first end face region transversely away from the axis of the piston rod, and the second end face region extends away from the screw rod below the first end face region. The end face shape design of the above-mentioned first end face region and the second end face region formed by the cleaning piston can extend into the vacuum hole as deep as possible without affecting the operation of the screw rod, and has better cleaning effect on the hole wall and the hole opening of the vacuum hole, so that the raw material pollution can be further prevented, the production continuity can be improved, the manual intervention can be reduced, and the product quality can be improved while saving the cost. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is the three-dimensional schematic view of the vacuum cleaning equipment for the screw extruder of following described embodiment 1;

[0024] Figure 2 It is Figure 1A perspective view of the vacuum cleaning device in the screw extruder;

[0025] Figure 3 For Figure 1 A cross-sectional view of the vacuum cleaning device in the screw extruder;

[0026] Figure 4 For Figure 3 A local enlarged view of A in the vacuum cleaning device;

[0027] Figure 5 A perspective view of the vacuum cleaning device for the screw extruder in Embodiment 2 below;

[0028] Figure 6 And Figure 7 are respectively Figure 5 Cross-sectional views of two different states of the vacuum cleaning device, in which one cleaning piston and the like structure is hidden for clarity, respectively.

[0029] [Legend of reference signs]

[0030] 1: piston rod; 2: cleaning piston; 2a: first end face area; 2b: second end face area; 3: barrel; 3a: vacuum hole; 4: screw; 5: vacuum box; 5a: inner cavity; 5b: feeding hole; 6: vacuum pipe; 7: air inlet pipe; 8: on-off valve; 9: four-way valve; 10: vacuum gauge; 11: pressure relief valve; 12: power source; a: included angle between the first end face area and the second end face area. DETAILED DESCRIPTION

[0031] In order to better explain the present application, so as to facilitate understanding, the present application is described in detail below through specific embodiments in combination with the drawings.

[0032] Embodiment 1

[0033] Referring to Figures 1 to 4 , the present embodiment provides a vacuum cleaning device for a screw extruder. The vacuum cleaning device comprises a vacuum device and a cleaning device. The vacuum device is used to communicate with the vacuum holes 3a on the barrel 3 of the screw extruder to suck out the hot steam and precipitates and the like in the barrel 3; the cleaning device is mainly used to clean the adhering substances inside the vacuum holes 3a and push the adhering substances into the vacuum device so that they are sucked away by the vacuum device.

[0034] Referring mainly to Figure 3 , the vacuum cleaning device of the present embodiment is adapted to an extruder with double screws 4, and the barrel 3 of the extruder is provided with two vacuum holes 3a with parallel axes, which correspond to the positions of the two screws 4 and extend towards the outer peripheral surface of the screws 4.

[0035] In this embodiment, the vacuum device includes a vacuum box 5 and a vacuum pipe 6 capable of being connected with a negative pressure device. The vacuum box 5 can be detachably mounted on the cylinder 3 by bolts, of course, the utility model is not limited to this, other convenient disassembly ways can be used. The bottom wall of the vacuum box 5 is provided with two feeding holes 5b in communication with the inner cavity 5a thereof, and the two feeding holes 5b can be in one-to-one correspondence with the two vacuum holes 3a. Thus, the feeding hole 5b, the inner cavity 5a of the vacuum box 5 and the vacuum pipe 6 form a vacuum material suction channel, and the hot steam and the precipitates in the cylinder 3 enter the inner cavity 5a of the vacuum box 5 through the vacuum hole 3a and the feeding hole 5b, and then are discharged to the vacuum barrel for collection through the vacuum pipe 6.

[0036] In this embodiment, the cleaning device includes a power source 12, two piston rods 1 and two cleaning pistons 2. The power source 12 in this embodiment is selected as a cylinder, of course, other power sources capable of providing equivalent driving functions can be selected in other embodiments. The cylinder body is detachably fixed on the vacuum box 5 by bolts, and the driving end of the cylinder is connected with one end of the two piston rods 1 through a connecting plate, and the other end of the two piston rods 1 is respectively threadedly connected with one cleaning piston 2. Of course, the connection mode of the cleaning piston 2 and the piston rod 1 is not limited to the threaded connection, and any detachable connection mode can be used to facilitate the replacement of the cleaning piston 2 and the adaptation of cleaning pistons 2 of different sizes.

[0037] Among them, two through holes are arranged on the top wall of the vacuum box 5 for the two piston rods 1 to pass through. The through holes on the top wall of the vacuum box 5 are coaxially arranged with the feeding holes of the vacuum box 5, and are coaxially arranged with the vacuum holes 3a, so that the piston rods 1 can be coaxially arranged with the vacuum holes 3a and move up and down along the axis thereof.

[0038] Among them, the size of the cleaning piston 2 is configured such that when the cleaning piston 2 works in the vacuum hole 3a, an annular gap is formed between the cleaning piston 2 and the inner wall of the vacuum hole 3a, which not only ensures the smooth movement of the cleaning piston 2, but also ensures that the hot steam in the cylinder 3 can pass over the cleaning piston 2 and enter the vacuum box 5. Preferably, the width of the annular gap is in the range of 1-2mm, so as to further ensure the cleaning effect.

[0039] Thus, the cylinder simultaneously drives the two piston rods 1 to move up and down, and the two piston rods 1 respectively drive the two cleaning pistons 2 to reciprocate in the two channels formed by the two vacuum holes 3a, the two feeding holes 5b and the cavity 5a, so as to push the residual substances on the inner walls of the vacuum holes 3a and the feeding holes 5b into the inner cavity 5a of the vacuum box 5. It is explained here that the piston rod 1 is always in reciprocating up and down motion when the screw extruder is running, so as to clean the adhered wet material on the inner wall of the cylinder 3 at any time.

[0040] Further combined Figure 3 and Figure 4In this embodiment, the cleaning piston 2 is cylindrical, meaning it has a circular outer circumference. Furthermore, the end face of the cleaning piston 2 is not a complete plane, but rather consists of a first end face region 2a and a second end face region 2b connected to each other. These two end face regions are arranged radially towards the screw 4, and their projections onto a plane perpendicular to the piston rod 1 are still circular. The first end face regions 2a of the two cleaning pistons 2 are positioned facing each other, meaning they are relatively close to each other, while the second end face regions 2b of the two cleaning pistons 2 are relatively far apart.

[0041] In this embodiment, the first end face region 2a is inclined relative to the axis of the piston rod 1. Since the piston rod 1 is vertical, the first end face region 2a can be referred to as an inclined plane. The inclination direction of this inclined plane is adapted to the circumferential inclination direction of the outer peripheral surface of the screw 4 below it, such as... Figure 3 and Figure 4 As shown, the left cleaning piston 2 is located slightly to the left of the left screw 4. The outer circumferential surface of the upper left half of the screw 4 is downward from right to left. Therefore, the first end face region 2a of the left cleaning piston 2 is inclined with the left side lower than the right side. The right cleaning piston 2 is located slightly to the right of the right screw 4. The outer circumferential surface of the upper right half of the screw 4 is downward from left to right. Therefore, the first end face region 2a of the right cleaning piston 2 is inclined with the left side higher than the right side.

[0042] The second end face region 2b is connected to the side of the first end face region 2a that is laterally away from the axis of the screw 4, such as... Figure 3 and Figure 4 As shown, the left cleaning piston 2 is located to the left of the left screw 4, and thus, the second end face region 2b of the left cleaning piston 2 is located to the left of the first end face region 2a; the right cleaning piston 2 is located to the right of the right screw 4, and thus, the second end face region 2b of the right cleaning piston 2 is located to the right of the first end face region 2a.

[0043] Meanwhile, the second end face region 2b extends relative to the first end face region 2a in a direction away from the screw 4 below it, such as... Figure 3 and Figure 4 As shown, the second end face region 2b of the left cleaning piston 2 bends upward relative to the left end of the first end face region 2a; the second end face region 2b of the right cleaning piston 2 bends upward at the right end of the first end face region 2a. In this embodiment, the second end face region 2b is perpendicular to the axis of the piston rod 1, and since the two piston rods 1 are vertically oriented in this embodiment, the second end face regions 2b of the two cleaning pistons 2 are horizontally oriented.

[0044] The inventor of the present utility model finds that the reason why the problem of raw material pollution still exists in the prior art is that the cleaning in the vacuum hole 3a is not thorough, especially the vacuum hole 3a is more likely to accumulate but difficult to clean near the hole opening position, and the cleaning effect in the vacuum hole 3a also needs to be improved. In this regard, the shape design of the first end face area 2a and the second end face area 2b formed by the cleaning piston 2 in the present embodiment can extend as deep as possible into the vacuum hole 3a without affecting the operation of the screw rod 4, and has a better cleaning effect on the hole opening and hole wall of the vacuum hole 3a, so as to further prevent raw material pollution, improve the continuity of production, reduce manual intervention, and thus improve product quality while saving costs.

[0045] Of course, the present utility model is not limited to the end face of the cleaning piston 2 consisting of only the first end face area 2a and the second end face area 2b, and the case of adding other end face areas based on the above shape design of the end face of the present utility model is also within the protection scope of the present embodiment.

[0046] Further, to maximize the cleaning effect of the vacuum cleaning device, the ratio of the width of the second end face area 2b to the length of the vacuum hole 3a is within the range of 1 / 3-1 / 4, and the ratio of the width of the second end face area 2b to the width of the cleaning piston 2 is less than 1 / 2. Among them, the above "width" is the size along the arrangement direction of the first end face area 2a and the second end face area 2b, and is also the size along the diameter direction of the screw rod. In this way, the cleaning piston 2 can extend as deep as possible into the vacuum hole 3a.

[0047] Further, the vacuum cleaning device of the present embodiment is committed to be suitable for more models of extruders, that is, when the extruder needs to replace or iterate the vacuum cleaning device, the vacuum cleaning device of the present embodiment is easily selected and matched, and the included angle a between the first end face area 2a and the second end face area 2b is set within the range of 150°-180°, more preferably within the range of 160°-170°. Generally, the inclination of the first end face area 2a is determined by the following way: taking the intersection of the axis of the piston rod 1 and the outer surface of the screw rod 4, making a tangent line of the outer surface of the screw rod 4 at the intersection, and the first end face area 2a is parallel to the tangent line. However, considering the orientation of the piston rod 1 and the model of the extruder, and considering the influence of the inclination of the first end face area 2a on the cleaning effect, etc., the above included angle value range is finally designed, which can balance the requirements of cleaning effect, universality, etc.

[0048] Through the above structural design, in the embodiment, the power source 12 can drive the cleaning piston 2 to move to the position where the distance between the cleaning piston 2 and the screw rod 3 is 5 mm, and stop at this position, at this time, the cleaning piston 2 will not interfere with the screw rod 4. The reciprocating frequency of the piston rod 1 driven by the power source 12 can be set on the touch screen according to different materials, generally 4-5 times per minute; the movement range of the piston rod 1 is generally about 100 mm according to the size of the barrel 3.

[0049] Further, after the cleaning piston 2 successfully pushes the material accumulated in the vacuum hole 3a into the vacuum box 5, due to the high temperature and humidity of the whole environment, the material is likely to stick to the cavity wall of the inner cavity 5a of the vacuum box 5. In view of this, the vacuum device is also further improved in the embodiment.

[0050] In the embodiment, the air inlet pipe 7 and the vacuum pipe 6 are coaxially connected at opposite ends of the vacuum box 5, and the axes of the air inlet pipe 7 and the vacuum pipe 6 are perpendicular to the axis of the feeding hole 5b.

[0051] The air inlet pipe 7 is provided with an on-off valve 8 to form an air inlet selectively connected with the outside. The on-off valve 8 is preferably a manual valve. When the on-off valve 8 is opened, a large amount of cold air enters the inner cavity 5a of the vacuum box 5 due to the pressure difference between the inside and the outside, and the humid material adhered to the cavity wall of the inner cavity 5a of the vacuum box 5 is blown off and sucked away by the vacuum. It should be noted that when the device is working, the temperature inside the device is higher than the temperature of the outside atmosphere, so the air entering from the outside is cold air relative to the environment of the inner cavity 5a of the vacuum box 5.

[0052] The end of the vacuum pipe 6 away from the air inlet pipe 7 is provided with a four-way valve 9. The first port of the four-way valve 9 is connected with the vacuum pipe 6. The second port is connected with a vacuum gauge 10. The third port is connected with a pressure relief valve 11, which is preferably a manual valve. The fourth port is used to connect with a negative pressure device.

[0053] Therefore, the air inlet, the inner cavity 5a of the vacuum box 5 and the vacuum pipe 6 are sequentially connected to form a cold air channel, and the two feeding holes 5b are both connected with the cold air channel. Therefore, the piston rod 1 can drive the cleaning piston 2 to reciprocate in the cold air channel, the feeding hole 5b and the vacuum hole 3a.

[0054] Further, the vacuum cleaning device of the embodiment further comprises a programmable controller (PLC) connected with the power source 12, the vacuum gauge 10 and the pressure relief valve 11, for automatically controlling the cleaning period, the cleaning parameters and the cleaning process, and ensuring the safety of the operator.

[0055] The working process of the vacuum cleaning device in the embodiment is described as follows:

[0056] In the process of extruding work of the screw extruder, the on-off valve 8 is closed, and the negative pressure device and the power source 12 are started at the same time. The hot steam in the cylinder 3 carries the precipitates and other substances into the inner cavity 5a of the vacuum box 5 from the vacuum hole 3a, and then is sucked away through the vacuum pipe 6. At the same time, the power source 12 always drives the piston rod 1 to reciprocate in the vacuum hole 3a and the vacuum box 5. The highest point of the cleaning piston 2 is located at the top wall of the vacuum box 5, and the lowest point of the cleaning piston 2 is located in the range of 5mm away from the screw 3. The cleaning piston 2 pushes the adhering substances on the inner wall of the vacuum hole 3a into the vacuum box 5, and then is sucked away through the vacuum pipe 6.

[0057] When the pressure value of the vacuum gauge 10 remains unchanged, and the current of the negative pressure device is higher than the previous current, it indicates that a certain amount of adhering substances is accumulated on the cavity wall of the inner cavity 5a of the vacuum box 5. Then the on-off valve 8 is opened, and the cold air enters the inner cavity 5a of the vacuum box 5. The adhering wet materials on the cavity wall of the inner cavity 5a are blown dry and fall into the inner cavity 5a, and are sucked away by the vacuum pipe 6.

[0058] In summary, the vacuum cleaning device of the embodiment improves the cleaning device and the vacuum device, and improves the cleaning ability of the vacuum cleaning device. At the same time, the vacuum device and the cleaning device are integrated, and can be independently disassembled and replaced relative to the extruder. The vacuum cleaning device of the embodiment is particularly suitable for the screw extruder in the floor production line, such as wood-plastic composite material production, stone-plastic composite material production, and luxury vinyl flooring. Of course, although the vacuum cleaning device of the embodiment is designed for a double-screw extruder, it can also be used for a triple-screw extruder and the like.

[0059] Embodiment Two

[0060] Referring to Figures 6-7 The main difference between the embodiment and the embodiment one is that the axes of the two vacuum holes 3a intersect in the embodiment. Correspondingly, two power sources 12 are provided, and the power output ends of the two power sources 12 are connected with the two piston rods 1 respectively.

[0061] In addition, the included angle between the two piston rods 1 is 30°, so that the cleaning piston 2 can clean the adhering wet materials on the inner wall of the inclined cylinder 3 and drop them. At the same time, the included angle between the first end surface area 2a and the second end surface area 2b in the embodiment is larger than that in the embodiment one by about 0.5°, but is still preferably located in the range of 164°-168°, so as to adapt to clean the adhering wet materials on the inner wall of the inclined cylinder 3 and improve the cleaning ability.

[0062] Therefore, in the embodiment, two power sources 12 can drive two piston rods 1 to alternately ascend and descend, so that the vacuum device has a better suction effect on the hot steam in the barrel 3. Of course, the two piston rods 1 in the first embodiment can also be respectively matched with an independent power source 12 to realize the alternate ascending and descending, or a positive and negative transmission mechanism is arranged between the power source 12 and the two piston rods 1 to realize the alternate ascending and descending of the two piston rods 1.

[0063] In the description of the present application, it should be understood that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more than two, unless otherwise specifically limited.

[0064] In the present application, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be connected, or it can be detachable, or it can be integrated; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For ordinary skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0065] In the present application, unless otherwise specifically defined and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through intermediate medium. Moreover, the first feature is "above", "above" and "above" the second feature, which can be directly above or obliquely above the first feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature is "below", "below" and "below" the second feature, which can be directly below or obliquely below the first feature, or only indicates that the horizontal height of the first feature is lower than that of the second feature.

[0066] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. Furthermore, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0067] Although the embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present application, and the person skilled in the art can modify, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A vacuum cleaning device for a screw extruder, comprising a piston rod (1) and a cleaning piston (2), the piston rod (1) being capable of driving the cleaning piston (2) to reciprocally clean a vacuum hole (3a) of a barrel (3) of the screw extruder; characterized in that: an end face of the cleaning piston (2) comprises a first end face area (2a) and a second end face area (2b) connected to each other, the first end face area (2a) is inclined relative to an axis of the piston rod (1) and the direction of inclination is adapted to a circumferential direction of an outer peripheral surface of a screw (4) below the first end face area (2a); the first end face area (2a) and the second end face area (2b) are arranged in a radial direction of the screw (4), the second end face area (2b) is connected to a side of the first end face area (2a) transversely away from the axis of the piston rod (1), and the second end face area (2b) extends relative to the first end face area (2a) in a direction away from the screw (4) below the second end face area (2b).

2. The vacuum cleaning device for a screw extruder according to claim 1, characterized in that: the second end face area (2b) is perpendicular to the axis of the piston rod (1).

3. The vacuum cleaning device for a screw extruder according to claim 1 or 2, characterized in that: a ratio of a width of the second end face area (2b) to a length of the vacuum hole (3a) is within a range of 1 / 3-1 / 4, and a ratio of the width of the second end face area (2b) to a width of the cleaning piston (2) is less than 1 / 2.

4. The vacuum cleaning device for a screw extruder according to claim 1 or 2, characterized in that: an included angle (a) between the first end face area (2a) and the second end face area (2b) is within a range of 150°-180°.

5. The vacuum cleaning device for a screw extruder according to claim 4, characterized in that: the included angle (a) between the first end face area (2a) and the second end face area (2b) is within a range of 160°-170°.

6. The vacuum cleaning device for a screw extruder according to claim 1 or 2, characterized in that: the cleaning piston (2) is cylindrical, and the cleaning piston (2) is configured to form an annular gap with an inner wall of the vacuum hole (3a) when the cleaning piston (2) works in the vacuum hole (3a), and a width of the annular gap is within a range of 1-2 mm.

7. The vacuum cleaning device for a screw extruder according to claim 1 or 2, characterized in that: the vacuum cleaning device further comprises a vacuum box (5) and a vacuum pipe (6) capable of being connected to an external negative pressure device; the vacuum box (5) is capable of being mounted on the barrel (3), and a bottom wall of the vacuum box (5) is provided with a feeding hole (5b) in communication with an inner cavity (5a) of the vacuum box (5), and the feeding hole (5b) is capable of being in communication with the vacuum hole (3a). ​ ​ ​ ​ ​ ​ ​ ​ ​ The vacuum pipe (6) is connected at one end of the vacuum box (5), and an air inlet selectively connected with the outside is arranged at the other end of the vacuum box (5), the air inlet, the inner cavity (5a) of the vacuum box (5) and the vacuum pipe (6) are sequentially communicated to form a cold air channel; The piston rod (1) can drive the cleaning piston (2) to reciprocate in the cold air channel, the feeding hole (5b) and the vacuum hole (3a).

8. The vacuum purge apparatus for a screw extruder as claimed in claim 7, characterized in that Further comprising an air inlet pipe (7); The air inlet pipe (7) and the vacuum pipe (6) are coaxially connected at opposite ends of the vacuum box (5), and a switching valve (8) is arranged on the air inlet pipe (7) to form the air inlet selectively connected with the outside; The end of the vacuum pipe (6) away from the air inlet pipe (7) is provided with a four-way valve (9), the first port of the four-way valve (9) is connected with the vacuum pipe (6), a vacuum gauge (10) is connected at the second port, a pressure relief valve (11) is connected at the third port, and the fourth port is used for connecting a negative pressure device; The switching valve (8) and the pressure relief valve (11) are both manual valves.

9. The vacuum cleaning device for a screw extruder according to claim 7, wherein, The vacuum cleaning device is provided with two piston rods (1), two cleaning pistons (2) and two feeding holes (5b) corresponding to two vacuum holes (3a), and the first end face areas (2a) of the two cleaning pistons (2) are oppositely arranged; The vacuum cleaning device further comprises a power source (12) fixed on the vacuum box (5), and the vacuum box (5) can be detachably fixed on the cylinder (3) through bolts; In the case that the axes of the two vacuum holes (3a) are parallel, one power source (12) is arranged, and the power output ends of the power source (12) are connected with the two piston rods (1) at the same time; In the case that the axes of the two vacuum holes (3a) intersect, two power sources (12) are arranged, and the power output ends of the two power sources (12) are respectively connected with the two piston rods (1); The piston rod (1) can be coaxially arranged with the vacuum hole (3a), and the power source (12) can drive the cleaning piston (2) to stop at a position where the distance between the lowest point of the cleaning piston (2) and the screw rod (4) is 3-5 mm.

10. The vacuum cleaning device for a screw extruder according to claim 1, wherein, The vacuum cleaning device is used for a screw extruder in a floor production line, and the end face of the cleaning piston (2) is composed of the first end face area (2a) and the second end face area (2b).

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