Multi-point spraying structure and spraying method for thermoplastic plastic

Abstract

The invention discloses a multi-point spraying structure and method for thermoplastic plastics in the technical field of plastic spraying, and the multi-point spraying structure comprises a spraying pipe which is a transversely-arranged strip-shaped spraying pipe, and the upper portion of the spraying pipe is provided with a plastic melt inlet used for being connected with a plastic melt injection pipe; the multiple spray heads are arranged below the spray pipe, and the multiple spray heads are evenly distributed in the length direction of the spray pipe so as to enlarge the spraying area of the plastic; each spray head is provided with a switch valve, and the spray heads at the corresponding positions and with the corresponding number can be selectively opened according to the width or length of the surface of a to-be-sprayed material, so that the spraying efficiency and the spraying precision are improved.

Description

Technical Field

[0001] The invention relates to the technical field of plastic spraying, and in particular to a multi-point spraying structure and a spraying method for thermoplastic plastics. Background Art

[0002] Plastics have become the most frequently used material in people's daily lives. With the continuous improvement of technology, plastics are widely used in the manufacture of building components, food containers, daily necessities, electrical appliance casings, aerospace vehicles, etc. In recent years, plastics have begun to be used in the manufacture of functional composite materials and other occasions.

[0003] Existing spraying devices are mostly improved and optimized in terms of spraying quality and spraying efficiency, for example:

[0004] CN201610813578.8 discloses a thermoplastic plastic powder spray-melting device, but a powder conveying section, a powder melting section and a droplet spraying section are arranged on the nozzle, so that the plastic powder can be melted in the powder melting section and sprayed into uniform liquid plastic particles through the droplet spraying section. When the liquid plastic particles reach the paved surface and solidify when cooled, they can be evenly dispersed, and defects such as discoloration, denaturation and burning of the plastic powder can be avoided.

[0005] CN111889261A discloses a thermoplastic powder spray melting device, which is provided with a gantry that can slide forward and backward on a bottom plate, and a spray pipe that can slide longitudinally on the gantry, thereby realizing the front-to-back and longitudinal position adjustment of the spray pipe, and the multiple nozzles provided at the bottom of the spray pipe can increase the spraying density and shorten the spraying time, thereby ensuring leveling before the liquid phase coating solidifies, and thus being able to adapt to the overall coating of large panels and improve work efficiency.

[0006] In fact, when spraying panels, it is often necessary to use one plastic spraying machine to spray panels of various specifications produced by the factory, but the current spray melting device in the factory is not convenient for adjusting the real-time spraying length.

[0007] When the spraying length of the spray melting device exceeds the length of the small plate, it will lead to waste of material. For example, when the spraying length is 2m and the length and width of the plate are both 1.5m, there will be 0.5m of ineffective spraying, resulting in material waste.

[0008] When the length of the large plate is not equal to an integer multiple of the spraying length of the spray melting device, it will also lead to material waste. For example, when the spraying length is 2m and the length and width of the plate are both 3m, the first spraying of a 2m long plate and the second spraying of a 1m long plate will result in 1m of ineffective spraying, resulting in material waste.

[0009] In summary, the current spray melting devices in factories are not convenient for adjusting the real-time spraying length and cannot be applied to panels of various specifications, resulting in serious ineffective spraying and material waste. Summary of the invention

[0010] The purpose of the present invention is to provide a multi-point spraying structure and a spraying method for thermoplastic plastics, so as to solve the technical problems in the prior art that the spray melting device is not convenient for adjusting the real-time spraying length, cannot be applied to panels of various specifications, and has serious ineffective spraying and material waste.

[0011] In order to solve the above technical problems, the present invention specifically provides a multi-point spraying structure of thermoplastics, comprising:

[0012] A nozzle, wherein the nozzle is a strip-shaped nozzle arranged transversely, and a plastic melt inlet for connecting to a plastic melt injection pipe is arranged at the upper portion of the nozzle;

[0013] A spray head, wherein a plurality of the spray heads are arranged below the spray pipe, and the plurality of the spray heads are evenly distributed in the length direction of the spray pipe to expand the sprayable range;

[0014] Each of the nozzles is provided with a switch valve, which can select and open the corresponding position and the corresponding number of nozzles according to the width or length of the surface of the material to be sprayed, so as to improve the spraying efficiency and spraying accuracy.

[0015] As a preferred solution of the present invention, a plurality of the nozzles are provided, and connecting pieces are provided at both ends of each nozzle, so that the plurality of nozzles can be combined and fixed to expand the spraying range.

[0016] As a preferred solution of the present invention, pressure monitors are evenly distributed in the nozzle for monitoring the pressure of the plastic melt in the nozzle; the switch valve is opened only when the monitored pressure is greater than the set pressure.

[0017] As a preferred solution of the present invention, a heat preservation device is wrapped around the outside of the nozzle to prevent the plastic melt in the nozzle from cooling and solidifying.

[0018] As a preferred solution of the present invention, the heat preservation device includes at least one layer of heat preservation cotton.

[0019] As a preferred solution of the present invention, the heat preservation device is configured as a heat preservation shell, and a cavity capable of flowing a heat exchange medium is provided in the shell;

[0020] The heat exchange medium is used to perform heat exchange with the plastic melt in the nozzle, so that the plastic melt in the nozzle remains in a molten state.

[0021] As a preferred solution of the present invention, the heat-insulating shell includes an upper shell and a lower shell, the upper shell and the lower shell are fixedly connected by bolts arranged at the edges, and a sealing ring is arranged at the joint between the upper shell and the lower shell;

[0022] The bottom of the lower shell is provided with a through hole for the nozzle to pass through, and the upper shell is provided with a through hole for the plastic melt injection pipe to pass through, and the through hole is not connected to the cavity for circulating the heat exchange medium;

[0023] The upper shell is provided with a medium inlet for injecting a heat exchange medium, and the lower shell is provided with a medium outlet for discharging the heat exchange medium and releasing the pressure in the cavity.

[0024] As a preferred solution of the present invention, the medium outlet is provided with a one-way valve to adjust the pressure and temperature in the cavity.

[0025] As a preferred solution of the present invention, the connecting piece is arranged at the end of the thermal insulation shell, and is used to connect multiple thermal insulation shells to expand the sprayable range of the multi-point spraying structure.

[0026] In order to solve the above technical problems, the present invention further provides a method for spraying thermoplastics.

[0027] Using the above-mentioned multi-point spraying structure includes the following steps:

[0028] Place the material to be sprayed under the nozzle, inject the plastic melt into the nozzle, and pressurize it. At this time, the nozzle is not turned on;

[0029] According to the width of the material surface, select the appropriate number of nozzles. When the pressure in the nozzle reaches the set value, open the selected nozzles to spray plastic on the material surface;

[0030] While spraying, the nozzle is moved along the length direction of the material at a predetermined speed through the displacement mechanism.

[0031] As a preferred solution of the present invention, a heat exchange medium is injected into the cavity through the medium inlet to perform heat exchange with the plastic melt in the nozzle, so that the plastic melt in the nozzle remains in a molten state;

[0032] The pressure at which the heat exchange medium is discharged is set by the pressure regulating valve. When the pressure in the cavity is greater than the set pressure of the pressure regulating valve, the heat exchange medium can be discharged from the cavity to increase the temperature in the cavity.

[0033] The heat exchange medium is injected before the plastic melt to preheat the nozzle and prevent the plastic melt from directly solidifying when it encounters the low-temperature nozzle.

[0034] The displacement mechanism moves the nozzle and the nozzle by moving the heat-insulating shell.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The multi-point spraying structure consists of a long nozzle and multiple nozzles. The number of nozzles opened can be adjusted according to the width of the material, and the spraying width can be adjusted adaptively so that the spraying length of the multi-point spraying structure is adapted to the width of the material, reducing the invalid spraying length and reducing material waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0038] Figure 1 It is a structural schematic diagram of a multi-point spraying structure and a heat-insulating shell in an embodiment of the present invention;

[0039] Figure 2 It is a schematic cross-sectional structure diagram of the heat-insulating shell in an embodiment of the present invention.

[0040] The numbers in the figure represent the following:

[0041] 1-nozzle, 2-nozzle, 3-insulation shell, 4-cavity, 5-upper shell, 6-lower shell, 7-bolt, 8-through hole, 9-medium inlet, 10-medium outlet, 11-connecting piece. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The present invention specifically provides a multi-point spraying structure for thermoplastics, comprising:

[0044] The nozzle 1 is a strip-shaped nozzle 1 arranged transversely, and a plastic melt inlet for connecting to a plastic melt injection pipe is arranged at the upper portion of the nozzle 1;

[0045] A spray head 2, wherein a plurality of spray heads 2 are arranged below the spray pipe 1, and the plurality of spray heads 2 are evenly distributed in the length direction of the spray pipe 1 to expand the sprayable range;

[0046] Each nozzle 2 is provided with a switch valve, which can select and open the corresponding position and the corresponding number of nozzles 2 according to the width or length of the surface of the material to be sprayed, so as to improve the spraying efficiency and spraying accuracy.

[0047] When using the multi-point nozzle 2 structure, first place the material to be sprayed under the nozzle 2, inject plastic melt into the nozzle 1, and select a suitable number of nozzles 2 to open according to the width of the material surface to spray plastic on the material surface; while spraying, the nozzle 1 is moved along the length direction of the material at a predetermined speed through the displacement mechanism.

[0048] The displacement mechanism can move the nozzle 1 in the horizontal x-axis direction and y-axis direction. For example, the nozzle 1 is slidably mounted on two guide rails in the x-axis direction and driven by a cylinder to move the nozzle 1 in the x-axis direction.

[0049] Then, the guide rail in the x-axis direction is slidably installed on the guide rail in the y-axis direction, and the x-axis guide rail is pushed to slide on the y-axis guide rail by the cylinder, so that the nozzle 1 slides in the y-axis direction.

[0050] Specifically, when the maximum spraying length of the nozzle 1 is 2 m and the width of the plate is 1.5 m, close an appropriate number of nozzles 2 to make the spraying length equal to or slightly greater than 1.5 m, thereby reducing the ineffective spraying length and reducing material waste.

[0051] When the length and width of the plate is 3m, a 2m long plate is sprayed for the first time, and a suitable number of nozzles 2 are closed for the second time, so that the spraying length is equal to or slightly greater than 1m, reducing the invalid spraying length and reducing material waste.

[0052] You can also adjust the spraying length to be equal to or slightly greater than 1.5m, and directly spray the 3m wide panel twice.

[0053] In summary, compared with the spray gun mentioned in the background technology, the multi-point spraying structure is composed of a long nozzle 1 and a plurality of nozzles 2. The number of nozzles 2 opened can be adjusted according to the width of the material, and the spraying width can be adjusted adaptively to make the spraying length of the multi-point spraying structure adapt to the width of the material, thereby reducing the invalid spraying length and reducing material waste.

[0054] Furthermore, a plurality of the nozzles 1 are provided, and connectors 11 are provided at both ends of each nozzle 1, so that the plurality of nozzles 1 can be combined and fixed to expand the spraying range.

[0055] If the width of the plate exceeds the length of a single nozzle 1 by a large amount, in order to reduce the number of spraying times and improve the spraying efficiency, a plurality of the nozzles 1 can be used in combination to further increase the maximum sprayable length.

[0056] Furthermore, during spraying, if the pressure in the nozzle 1 is not high enough, the speed of the molten plastic sprayed from the nozzle 2 and the diffusion area of ​​the molten plastic when being sprayed will be unsatisfactory, thus affecting the spraying effect.

[0057] This phenomenon is particularly serious when the nozzle 2 starts working. To avoid this phenomenon, we take the following measures:

[0058] When injecting the plastic melt, the nozzle 2 is not opened immediately, but the plastic melt is first continuously injected into the nozzle 1. When there is enough plastic melt in the nozzle 1, the melt pressure will increase.

[0059] Pressure monitors are evenly distributed in the nozzle 1 to monitor the pressure of the plastic melt in the nozzle 1; when the monitored pressure is greater than the set pressure, the switch valve on the corresponding nozzle 2 is opened.

[0060] Furthermore, since the multi-point nozzle 2 structure is composed of the nozzle 1 and the nozzle 2 , the heated and melted plastic melt is not sprayed out immediately, but needs to be transferred through the nozzle 1 .

[0061] Therefore, the time interval from the melting of the plastic melt to the ejection of the plastic melt is prolonged, resulting in the risk of the plastic melt cooling and solidification.

[0062] In order to reduce or avoid this risk, the nozzle 1 is wrapped with a heat preservation device to prevent the plastic melt in the nozzle 1 from cooling and solidifying.

[0063] Optionally, the heat-insulating device includes at least one layer of heat-insulating cotton, which can slow down the air flow outside the nozzle 1, reduce the heat exchange rate, and delay the loss of temperature of the plastic melt.

[0064] Optionally, the heat preservation device is configured as a heat preservation shell 3, and a cavity 4 capable of flowing a heat exchange medium is provided in the shell.

[0065] The heat exchange medium is used to perform heat exchange with the plastic melt in the nozzle 1 so as to keep the plastic melt in the nozzle 1 in a molten state.

[0066] After the heat exchange medium is filled in the cavity 4, the temperature in the cavity 4 rises rapidly until the temperature in the cavity 4 is higher than the temperature of the plastic melt. Since the inner wall of the cavity 4 and the tube wall of the nozzle 1 are both made of materials with good thermal conductivity, the high temperature of the cavity 4 can prevent the temperature of the plastic melt in the nozzle 1 from decreasing, or even increase, thereby eliminating the possibility of cooling of the plastic melt.

[0067] It is understandable that the heat exchange medium can be a liquid having a boiling point higher than the melting point of the plastic at normal pressure.

[0068] At this time, the displacement mechanism indirectly moves the nozzle 1 by moving the heat-insulating shell 3.

[0069] Furthermore, according to the structural shape characteristics of the nozzle 1 and the nozzle 2 , we designed the structure of the thermal insulation shell 3 so that the thermal insulation shell 3 can be completely wrapped and fit on the outside of the nozzle 1 .

[0070] The details are as follows:

[0071] The heat-insulating shell 3 includes an upper shell 5 and a lower shell 6 . The upper shell 5 and the lower shell 6 are fixedly connected by bolts 7 arranged at the edges, and a sealing ring is arranged at the joint between the upper shell 5 and the lower shell 6 .

[0072] The bottom of the lower shell 6 is provided with a through hole 8 for the nozzle 2 to pass through, and the upper shell 5 is provided with a through hole 8 for the plastic melt injection pipe to pass through. The through hole 8 is not connected to the cavity 4 for circulating the heat exchange medium.

[0073] The upper shell 5 is provided with a medium inlet 9 for injecting a heat exchange medium, and the lower shell 6 is provided with a medium outlet 10 for discharging the heat exchange medium and releasing the pressure in the cavity 4 .

[0074] When installing the insulation shell 3, first pass the plastic melt injection pipe through the through hole 8 and connect it to the melt inlet on the nozzle 1, then put the lower shell 6 under the nozzle 1, and let the nozzle 2 pass through the corresponding through hole 8, finally align the upper shell 5 with the lower shell 6, and fix them with bolts 7, and connect the cut-off injection pipe to the medium inlet 9 on the upper shell 5.

[0075] Furthermore, in order to save costs, the heat exchange medium may also be set to steam. In order to increase the temperature in the cavity 4 to a level higher than the plastic melt after the steam enters the cavity 4, a one-way valve is set at the medium outlet 10 on the lower shell 6. The one-way valve is opened only when the pressure in the cavity 4 reaches the set value.

[0076] That is, high-temperature steam needs to be continuously and rapidly injected into the cavity 4. During this process, since the volume of the cavity 4 is fixed, the temperature in the cavity 4 will continue to rise with the injection of high-temperature steam. When the pressure reaches the set value, the temperature in the cavity 4 is higher than the temperature of the plastic melt, and the one-way valve opens to release water vapor.

[0077] Then, the steam is injected slowly to maintain the temperature in the cavity 4 .

[0078] Furthermore, the connecting member 11 is disposed at the end of the heat-insulating shell 3, and is used to connect a plurality of heat-insulating shells 3, so as to expand the sprayable range of the multi-point spraying structure.

[0079] It is understandable that the types of the connecting member 11 can be varied. For example, an insert block is fixedly provided at one end of the heat-insulating shell 3, and a slot is fixedly provided at the other end.

[0080] When connecting two heat-insulating shells 3, the plug block of one heat-insulating shell 3 is plugged into the slot of the other heat-insulating shell 3, and then a latch is used to penetrate the plug block and the slot from top to bottom, so that the two heat-insulating shells 3 can be fixedly connected.

[0081] In order to solve the above technical problems, the present invention further provides a method for spraying thermoplastics.

[0082] Using the above multi-point nozzle 2 structure includes the following steps:

[0083] Place the material to be sprayed under the nozzle 2, inject the plastic melt into the nozzle 1, and pressurize it. At this time, the nozzle 2 is not turned on;

[0084] According to the width of the material surface, select a suitable number of nozzles 2, and when the pressure in the nozzle 1 reaches the set value, open the selected nozzles 2 to spray plastic on the material surface;

[0085] While spraying, the nozzle 1 is moved along the length direction of the material at a predetermined speed by the displacement mechanism.

[0086] Compared with the spray gun mentioned in the background technology, the multi-point spray head 2 structure consists of a long strip nozzle 1 and multiple spray heads 2, and has a larger spray width and higher spray efficiency. In addition, the number of nozzles 2 opened can be adjusted according to the width of the material, and the spray width can be adjusted to adapt to the width of the nozzle 2 of the multi-point spray head 2 structure to the width of the material, thereby improving the spraying accuracy.

[0087] As a preferred solution of the present invention, a heat exchange medium is injected into the cavity 4 through the medium inlet 9 to perform heat exchange with the plastic melt in the nozzle 1, so that the plastic melt in the nozzle 1 remains in a molten state;

[0088] The pressure at which the heat exchange medium is discharged is set by the pressure regulating valve. When the pressure in the cavity 4 is greater than the set pressure of the pressure regulating valve, the heat exchange medium can be discharged from the cavity 4, so as to increase the temperature in the cavity 4.

[0089] The heat exchange medium is injected before the plastic melt to preheat the nozzle 1, so as to prevent the plastic melt from directly solidifying when it encounters the low-temperature nozzle 1;

[0090] The displacement mechanism moves the nozzle 1 and the nozzle 2 by moving the heat-insulating shell 3 .

[0091] For example, when the heat exchange medium is water vapor, in order to increase the temperature in the cavity 4 to a level higher than the plastic melt after the steam enters the cavity 4, a one-way valve is set at the medium outlet 10 on the lower shell 6. The one-way valve is opened only when the pressure in the cavity 4 reaches the set value.

[0092] That is, high-temperature steam needs to be continuously and rapidly injected into the cavity 4. During this process, since the volume of the cavity 4 is fixed, the temperature in the cavity 4 will continue to rise with the injection of high-temperature steam. When the pressure reaches the set value, the temperature in the cavity 4 is higher than the temperature of the plastic melt, and the one-way valve opens to release water vapor.

[0093] Then, the steam is injected slowly to maintain the temperature in the cavity 4 .

[0094] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present application.

Claims

1. A multi-point spraying structure for thermoplastics, characterized in that: include: A nozzle (1), wherein the nozzle (1) is a strip-shaped nozzle (1) arranged transversely, and a plastic melt inlet for connecting to a plastic melt injection pipe is arranged at the upper portion of the nozzle (1); A spray head (2), wherein a plurality of the spray heads (2) are arranged below the spray pipe (1), and the plurality of the spray heads (2) are evenly distributed in the length direction of the spray pipe (1) to expand the sprayable range; Each of the spray heads (2) is provided with a switch valve, which can select and open a corresponding position and a corresponding number of the spray heads (2) according to the width of the surface of the material to be sprayed, so as to improve the spraying efficiency and spraying accuracy.

2. A multi-point spraying structure for thermoplastics according to claim 1, characterized in that: A plurality of the nozzles (1) are provided, and connecting pieces (11) are provided at both ends of each nozzle (1), so that the plurality of nozzles (1) can be combined and fixed to expand the spraying range.

3. A nozzle (2) for a thermoplastic melt spraying device according to claim 1 or 2, characterized in that: The nozzle (1) is wrapped with a heat preservation device to keep the plastic melt in the nozzle (1) in a molten state.

4. A multi-point spraying structure for thermoplastics according to claim 3, characterized in that: The heat preservation device comprises at least one layer of heat preservation cotton.

5. The multi-point spraying structure of thermoplastics according to claim 3, characterized in that: The heat preservation device is provided as a heat preservation shell (3), and a cavity (4) capable of circulating a heat exchange medium is provided in the shell; The heat exchange medium is used to perform heat exchange with the plastic melt in the nozzle (1), so that the plastic melt in the nozzle (1) remains in a molten state.

6. A multi-point spraying structure for thermoplastics according to claim 5, characterized in that: The heat-insulating shell (3) comprises an upper shell (5) and a lower shell (6); the upper shell (5) and the lower shell (6) are fixedly connected by bolts (7) arranged at the edges, and a sealing ring is arranged at the joint between the upper shell (5) and the lower shell (6); The bottom of the lower shell (6) is provided with a through hole (8) for the nozzle (2) to pass through, and the upper shell (5) is provided with a through hole (8) for the plastic melt injection pipe to pass through, and the through holes (8) are not connected to the cavity (4) for circulating the heat exchange medium; The upper shell (5) is provided with a medium inlet (9) for injecting a heat exchange medium, and the lower shell (6) is provided with a medium outlet (10) for discharging the heat exchange medium and releasing the pressure in the cavity (4).

7. A multi-point spraying structure for thermoplastics according to claim 6, characterized in that: The medium outlet (10) is provided with a one-way valve to adjust the pressure and temperature in the cavity (4).

8. The multi-point spraying structure of thermoplastics according to claim 6, characterized in that: The connecting piece (11) is arranged at the end of the heat-insulating shell (3) and is used to connect a plurality of heat-insulating shells (3) to expand the sprayable range of the multi-point spraying structure.

9. A method for spraying thermoplastics, characterized in that: Using the multi-point spraying structure according to claim 8 comprises the following steps: The material to be sprayed is placed under the nozzle (2), and the plastic melt is injected into the nozzle (1) and pressurized, while the nozzle (2) is not turned on; According to the width of the material surface, a suitable number of nozzles (2) are selected, and when the pressure in the nozzle (1) reaches a set value, the selected nozzles (2) are turned on to spray plastic on the material surface; While spraying, the nozzle (1) is moved along the length direction of the material at a predetermined speed through a displacement mechanism.

10. A method for spraying thermoplastics according to claim 9, characterized in that: Injecting a heat exchange medium into the cavity (4) through a medium inlet (9) to perform heat exchange with the plastic melt in the nozzle (1), so that the plastic melt in the nozzle (1) remains in a molten state; The pressure at which the heat exchange medium is discharged is set by the pressure regulating valve. When the pressure in the cavity (4) is greater than the set pressure of the pressure regulating valve, the heat exchange medium can be discharged from the cavity (4) so ​​as to increase the temperature in the cavity (4); The heat exchange medium is injected before the plastic melt, so as to preheat the nozzle (1) and prevent the plastic melt from directly solidifying due to the low temperature of the nozzle (1). The displacement mechanism moves the nozzle (1) and the nozzle (2) by moving the heat-insulating shell (3).

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