Full-working-condition self-adaptive release agent smearing device and control method

Abstract

The invention discloses a full-working-condition self-adaptive release agent smearing device and a control method thereof.A soft smearing head is arranged at the tail end of a multi-axis smearing mechanical arm, and the corner angle of the soft smearing head can be used for conducting probing type smearing on a special-shaped dead angle area of an inner cavity of a segment grinding tool; uniform and efficient coating of complex curved surfaces and dead corners of an inner cavity of a mold is achieved, splashing and leakage of a release agent in a traditional spraying process can be remarkably reduced, the quality consistency of a coating is improved, meanwhile, raw material consumption and environmental pollution risks are reduced, and the production cost is reduced. And in the moving intermittent period of the multi-shaft smearing mechanical arm, after single-time or staged smearing operation is finished or all smearing operation is finished, the residual release agent on the liquid supply head and the soft smearing head can be recycled, and waste of the release agent is avoided.

Description

Technical Field

[0001] This invention relates to the field of precast concrete component production equipment technology, and in particular to a device and control method for adaptive application of release agent under all working conditions. Background Technology

[0002] In the construction of underground projects such as tunnels and urban integrated utility tunnels, precast concrete segments are key structural components. Their production typically uses high-precision steel molds for casting, and uniformly coating the inner wall of the mold with a release agent before pouring concrete is one of the core processes to ensure smooth demolding and a smooth, defect-free surface for the segments.

[0003] Although some automated spraying equipment has emerged in the market, its ability to cover complex "dead corners" such as bolt holes and deep grooves within molds is limited, and it cannot effectively solve the waste and pollution problems caused by mold release agent splashing and dripping. Therefore, the industry urgently needs an automated solution that can achieve uniform, precise, efficient, and clean coating to improve the production quality, efficiency, and environmental protection level of precast tunnel segments. Summary of the Invention

[0004] In view of this, the present invention provides an apparatus and control method for adaptive application of release agent under all working conditions. The present invention can significantly reduce the splashing and leakage of release agent in traditional spraying processes, and achieve uniform and efficient application to complex curved surfaces and dead corners inside the mold cavity. While improving the consistency of coating quality, it reduces the risk of raw material consumption and environmental pollution.

[0005] An all-condition adaptive release agent application device includes a segment mold set at a designated station on the production line, a multi-axis application robot arm set on one side of the segment mold and opposite to the station of the segment mold, an application execution mechanism detachably set at the end of the multi-axis application robot arm, a funnel-shaped maintenance box set within the working range of the multi-axis application robot arm, a release agent storage and supply unit, and a controller. The multi-axis application robot arm, the application execution mechanism, and the release agent storage and supply unit are all electrically connected to the controller. The coating actuator includes a soft coating head that can actively probe into the cavity of the segment mold to apply release agent. The funnel-shaped maintenance box is used to support the coating actuator during the intermittent movement of the multi-axis coating robot or after the coating operation is completed, so as to collect residual release agent on the soft coating head. The release agent storage and supply unit includes a storage tank for storing release agent, a conveying pipe connected to the outlet of the storage tank via a pipeline, a supply pipe connected to the conveying pipe, and a recovery pipe. The supply pipe is connected to the application execution mechanism, and one end of the recovery pipe is connected to the return port of the storage tank, and the other end is connected to the application execution mechanism and the funnel-shaped maintenance box respectively to recover the residual release agent in the application execution mechanism and the funnel-shaped maintenance box.

[0006] Preferably, it also includes an optical identification unit for production monitoring and identification of the segment mold model. The optical identification unit is electrically connected to the controller and is located next to a designated workstation of the segment mold.

[0007] Preferably, it also includes an end effector library, which is located within the working range of the multi-axis smearing robot arm and contains smearing actuators of various specifications.

[0008] Preferably, the end effector library is provided with multiple positioning seats, each positioning seat is equipped with a coating execution mechanism, and each positioning seat or coating execution mechanism is provided with a readable identification code for storing its model data.

[0009] Preferably, the application mechanism further includes a rotary drive fixed to the end of the multi-axis application robot arm, a liquid supply head fixed to the drive shaft of the rotary drive, one branch of the liquid supply pipe and the recovery pipe passing through the inside of the multi-axis application robot arm and extending into the liquid supply head, the liquid supply head having several liquid outlet holes, and the soft application head wrapped around the outside of the liquid supply head.

[0010] Preferably, the soft applicator is a square sponge applicator.

[0011] Preferably, the funnel-shaped maintenance box includes an outer shell, a funnel-shaped grid disposed inside the outer shell, and another branch of the recovery pipe extending to the bottom of the cavity of the outer shell.

[0012] Preferably, the liquid storage tank is further provided with a temperature sensor for detecting the temperature of the release agent and a temperature control module for adjusting the temperature of the release agent. Both the temperature sensor and the temperature control module are electrically connected to the controller.

[0013] Preferably, a metering pump and a liquid supply valve are installed on the conveying pipe, and a negative pressure pump is installed on the recovery pipe.

[0014] A control method for the above-described device specifically includes the following steps: S1, transport the tube segment mold to the designated station on the production line, the optical recognition unit identifies the model of the tube segment mold and transmits the data to the controller, the controller controls the multi-axis coating robot arm to rotate to the end effector library according to the data it receives, and matches and installs the corresponding model of coating actuator from the end effector library; S2, the controller controls the mold release agent storage and supply unit to supply liquid to the coating execution mechanism in a quantitative manner. At the same time, the controller controls the multi-axis coating robot arm and the rotary drive to work together so that the wetted soft coating head can apply the mold release agent in all directions along the inner cavity of the tube mold. S3, During the intermittent movement of the multi-axis coating robot arm, the controller controls the negative pressure pump to recover the residual release agent in the liquid supply head through the recovery pipe; S4. After a single or phased coating operation is completed, the controller controls the multi-axis coating robot arm to rotate so that the soft coating head is temporarily placed in the funnel-shaped maintenance box. The residual release agent on the soft coating head drips and is collected in the funnel-shaped maintenance box. S5. After all coating operations are completed, the controller controls the multi-axis coating robot arm to rotate, placing the soft coating head in the funnel-shaped maintenance box. Then, the controller controls the multi-axis coating robot arm to press down on the soft coating head to squeeze out the release agent remaining inside the soft coating head. Then, the negative pressure pump is started to recover the release agent in the funnel-shaped maintenance box through the recovery pipe.

[0015] The beneficial effects of this invention are: 1. This invention, by setting a soft coating head at the end of a multi-axis coating robot arm, utilizes the edges and corners of the soft coating head to perform penetrating coating on irregular dead corner areas inside the mold cavity, achieving uniform and efficient coating on complex curved surfaces and dead corners of the mold cavity. This significantly reduces the splashing and leakage of release agent in traditional spraying processes, improving the consistency of coating quality while reducing raw material consumption and environmental pollution risks. Furthermore, during the intermittent movement of the multi-axis coating robot arm, after a single or staged coating operation, or after all coating operations are completed, the release agent remaining on the liquid supply head and the soft coating head can be recovered, avoiding waste of release agent.

[0016] 2. The pulse supply and negative pressure recovery of the release agent storage and supply unit of the present invention are mutually exclusive and coordinated in operation sequence, forming a "supply-recovery" closed loop, which eliminates the leakage and waste of release agent from the source.

[0017] 3. The release agent storage and supply unit of the present invention is equipped with a temperature control module, which can automatically adjust the temperature of the release machine to adjust the viscosity of the release machine and ensure the consistency of the coating quality under different environmental temperatures such as extreme cold and heat.

[0018] 4. The optical recognition unit and end effector library of the present invention work together to realize the automatic replacement of the coating execution mechanism and the rapid adaptation of multiple types of tube sheet molds. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of the present invention.

[0021] Figure 2 This is a schematic diagram of the smearing actuator.

[0022] Figure 3 This is a schematic diagram of the soft application head.

[0023] Figure 4 This is a schematic diagram of the mold release agent storage and supply unit.

[0024] Figure 5 This is a structural diagram of a funnel-shaped maintenance box.

[0025] The meanings of the labels in the diagram are as follows: 1 is the segment mold. 2 is a multi-axis coating robotic arm. 3 is the applicator, 31 is the rotary drive, 32 is the liquid supply head, and 33 is the soft applicator head. 4 is an optical recognition unit. 5 represents the controller. 6 is the mold release agent storage and supply unit; 61 is the storage tank; 62 is the metering pump; 63 is the delivery pipe; 64 is the temperature control module; 65 is the temperature sensor; 66 is the negative pressure pump; 67 is the supply valve; 68 is the supply pipe; and 69 is the recovery pipe. 7 is a funnel-shaped maintenance box. 8 is the end effector library. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0027] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0028] In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two components. They can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0029] In the following description, suffixes such as "module," "part," or "unit" used to denote elements are used only for the convenience of the description of the invention and have no specific meaning in themselves. Therefore, "module" and "part" can be used interchangeably.

[0030] To better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings.

[0031] This invention provides an all-condition adaptive release agent application device, comprising a segment mold 1 set at a designated work station on the production line, a multi-axis application robot arm 2 set on one side of the segment mold 1 and opposite to the work station of the segment mold 1, an application execution mechanism 3 detachably set at the end of the multi-axis application robot arm 2, a funnel-shaped maintenance box 7 set within the working range of the multi-axis application robot arm 2, a release agent storage and supply unit 6, and a controller 5. The multi-axis application robot arm 2, the application execution mechanism 3, and the release agent storage and supply unit 6 are all electrically connected to the controller 5.

[0032] The multi-axis coating robotic arm 2 is used to drive the coating actuator 3 to perform actions such as applying the release agent and recovering the release agent residue on the coating actuator 3. In this embodiment, the multi-axis coating robotic arm 2 is a five-axis or more articulated robotic arm. Its multi-joint robotic arm, controlled by the controller 5, can achieve 360° operation without blind spots and accurately complete the application of the release agent for the pipe segment.

[0033] The application mechanism 3 is detachably mounted at the end of the multi-axis application robot arm 2. The application mechanism 3 includes a rotary drive 31, a liquid supply head 32, and a soft application head 33. The rotary drive 31 is fixed to the end of the multi-axis application robot arm 2, the liquid supply head 32 is fixed to the drive shaft of the rotary drive 31, and the soft application head 33 is wrapped around the outside of the liquid supply head 32. The liquid supply head 32 has an internal cavity with several outlet holes on its surrounding sides. When the release agent enters the liquid supply head 32, it flows out from the outlet holes and then soaks into the pores of the soft application head 33. After the soft application head 33 is soaked, the rotary drive 31 drives the soft application head 33 to rotate, actively applying the release agent into the inner cavity of the tube mold.

[0034] In this embodiment, the soft applicator 33 is a square sponge applicator. Its edges can penetrate into the irregular area inside the tube mold cavity during rotation. The four planes alternately contact the hole wall as they rotate, forming an active penetration applicator for dead corner areas, thereby effectively applicating the dead corner positions.

[0035] The mold release agent storage and supply unit 6 stores mold release agent and supplies it to the liquid supply head 32. It also recovers residual mold release agent from the soft application head 33 and the funnel-shaped maintenance box 7. The mold release agent storage and supply unit 6 includes a storage tank 61 for storing mold release agent, a delivery pipe 63 connected to the outlet of the storage tank 61 via a pipe, a supply pipe 68 connected to the delivery pipe 63, and a recovery pipe 69. A metering pump 62 and a supply valve 67 are installed on the delivery pipe 63. The delivery pipe 63 is connected to the supply pipe 68. One end of the recovery pipe 69 is connected to the return port of the storage tank 61. One branch of both the supply pipe 68 and the recovery pipe 69 passes through the interior of the multi-axis application robot arm 2 and extends into the liquid supply head 32. The other branch of the recovery pipe 69 extends into the funnel-shaped maintenance box 7. A negative pressure pump 66 is installed on the recovery pipe 69.

[0036] During the coating operation, the controller 5 retrieves the pre-stored operation parameters and controls the movement trajectory of the multi-axis coating robot arm 2 and the rotation of the rotary drive 31. It then adjusts the opening frequency and duty cycle of the liquid supply valve 67 in real time. The metering pump 62 and the liquid supply valve 67 deliver the release agent in the storage tank 61 to the liquid supply head 32 in a pulse manner through the conveying pipe 63 and the liquid supply pipe 68. During the intermittent movement of the multi-axis coating robot arm 2, the negative pressure pump 66 recovers the residual release agent in the liquid supply head 32 to the storage tank 61 through the recovery pipe 69.

[0037] In this embodiment, the liquid supply valve 67 is a high-frequency solenoid valve, and its opening frequency and duty cycle are dynamically adjusted by the controller 5 according to the application speed, the specifications of the soft application head 33, and the real-time viscosity of the release agent. The opening of the liquid supply valve 67 and the negative pressure pump 66 are mutually exclusive in timing.

[0038] Preferably, in a preferred embodiment, the storage tank 61 is further equipped with a temperature sensor 65 for detecting the temperature of the release agent and a temperature control module 64 for adjusting the temperature of the release agent. Both the temperature sensor 65 and the temperature control module 64 are electrically connected to the controller 5. The temperature sensor 65 and the temperature control module 64 cooperate to maintain the release agent in the storage tank 61 at the target temperature so as to calculate the real-time viscosity of the release agent. The temperature of the release agent needs to be adjusted according to the model of the tube mold 1. The correspondence between the model of the tube mold 1 and the optimal temperature of the release machine is stored in advance in the controller 5. The temperature sensor 65 detects the temperature of the release agent in the storage tank 61 in real time and transmits the temperature signal to the controller 5. The controller 5 compares the temperature signal it receives with the target temperature corresponding to the model of the tube mold 1, and controls the temperature control module 64 according to the temperature deviation between the two to make it cool or heat.

[0039] Preferably, in a preferred embodiment, a heat insulation layer may also be provided on the inner wall of the liquid storage tank 61.

[0040] The funnel-shaped maintenance box 7 is used to support the coating actuator 3 after the coating operation to collect residual release agent on the soft coating head 33. The funnel-shaped maintenance box 7 includes a housing and a funnel-shaped grid disposed inside the housing. After a single coating operation, the multi-axis coating robot arm 2 moves the soft coating head 33 and places it on the funnel-shaped grid, and the residual release agent on the soft coating head 33 drips into the funnel-shaped maintenance box 7; after all operations are completed, the multi-axis coating robot arm 2 can drive the soft coating head 33 to move and place it on the funnel-shaped grid, and squeeze the soft coating head 33 against the funnel-shaped grid by pressing down to expel the residual liquid inside the soft coating head 33, while activating the negative pressure pump 66 to recover the extruded release agent through the recovery pipe 69.

[0041] In this embodiment, the funnel-shaped grid inside the funnel-shaped maintenance box 7 is a funnel-shaped plastic grid.

[0042] Preferably, the device further includes an optical identification unit 4 for production monitoring and identification of the model of the segment mold 1. The optical identification unit 4 is electrically connected to the controller 5 and is located next to the designated work station of the segment mold 1.

[0043] Preferably, the device further includes an end effector library 8, which is located within the working range of the multi-axis applicator arm 2, and contains applicator mechanisms 3 of various specifications.

[0044] In this embodiment, the end effector library 8 is provided with multiple positioning seats, each positioning seat is equipped with a coating execution mechanism 3, and each positioning seat or coating execution mechanism 3 is provided with a readable identification code for storing its model data.

[0045] After the optical recognition unit 4 identifies the model of the tube mold 1, it transmits the data to the controller. The controller controls the multi-axis coating robot arm 2 to rotate and move the multi-axis coating robot arm 2 above the coating actuator 3 of the corresponding model in the end effector library 8. Then, it controls the multi-axis coating robot arm 2 to descend and align with the coating actuator 3, so that the two can be assembled. This allows the multi-axis coating robot arm 2 to automatically change the coating actuator 3 at its end.

[0046] In this embodiment, the optical recognition unit 4 can be a vision camera, specifically a CCD or CMOS industrial camera, used to collect feature information of the mold surface, including mold outline, model stamp, QR code or barcode, and complete model recognition through image recognition algorithm.

[0047] The present invention also provides a control method for the above-described device, specifically comprising the following steps: S1, transport the tube mold 1 to the designated station on the production line. The optical recognition unit 4 identifies the model of the tube mold 1 and transmits the data to the controller 5. The controller 5 controls the multi-axis coating robot arm 2 to rotate to the end effector library 8 according to the data it receives. The corresponding model of the coating execution mechanism 3 is matched from the end effector library 8 and the coating execution mechanism 3 is automatically installed at the end of the robot arm. At the same time, the controller 5 retrieves the set temperature of the release agent corresponding to the model of the mold 1 from its internal storage chip, and controls the temperature control module 64 of the release agent storage and supply unit 6 to adjust the temperature in the storage tank 61 according to the set temperature of the release agent.

[0048] S2, the controller 5 controls the start of the release agent storage and supply unit 6, which supplies the release agent to the soft application head 33 in a pulse manner through the metering pump 62 and the liquid supply valve 67. At the same time, the controller 5 controls the multi-axis application robot arm 2 and the rotary drive 31 to work together, so that the wetted soft application head 33 can apply the release agent in all directions along the inner cavity of the tube mold 1.

[0049] S3, during the intermittent movement of the multi-axis coating robot arm 2, the controller 5 controls the negative pressure pump 66 to recover the residual release agent in the liquid supply head 32 through the recovery pipe 69.

[0050] S4. After a single or phased application operation is completed, the controller 5 controls the multi-axis application robot arm 2 to rotate so that the soft application head 33 is temporarily placed in the funnel-shaped maintenance box 7. The residual release agent on the soft application head 33 drips into the funnel-shaped maintenance box 7 for recycling and collection.

[0051] S5, after all coating operations are completed, the controller 5 controls the multi-axis coating robot arm 2 to rotate, placing the soft coating head 33 in the funnel-shaped maintenance box 7, and then controls the multi-axis coating robot arm 2 to press down the soft coating head 33 to squeeze out the release agent remaining inside the soft coating head 33. Then, the negative pressure pump 66 is started to recover the release agent in the funnel-shaped maintenance box 7 through the recovery pipe 69.

[0052] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A device for adaptive application of release agent under all working conditions, characterized in that, The system includes a segment mold (1) set at a designated workstation on the production line, a multi-axis coating robot arm (2) set on one side of the segment mold (1) and opposite to the workstation of the segment mold (1), a coating execution mechanism (3) detachably set at the end of the multi-axis coating robot arm (2), a funnel-shaped maintenance box (7) set within the working range of the multi-axis coating robot arm (2), a release agent storage and supply unit (6), and a controller (5). The multi-axis coating robot arm (2), the coating execution mechanism (3), and the release agent storage and supply unit (6) are all electrically connected to the controller (5). The coating actuator (3) includes a soft coating head (33) that can actively probe into the cavity of the segment mold to apply release agent. The funnel-shaped maintenance box (7) is used to support the coating actuator (3) during the movement interval of the multi-axis coating robot (2) or after the coating operation is completed to collect residual release agent on the soft coating head (33). The release agent storage and supply unit (6) includes a storage tank (61) for storing release agent, a conveying pipe (63) connected to the outlet of the storage tank (61) via a pipeline, a supply pipe (68) connected to the conveying pipe (63), and a recovery pipe (69). The supply pipe (68) is connected to the application execution mechanism (3). One end of the recovery pipe (69) is connected to the return port of the storage tank (61), and the other end is connected to the application execution mechanism (3) and the funnel mesh maintenance box (7) respectively to recover the residual release agent in the application execution mechanism (3) and the funnel mesh maintenance box (7).

2. The apparatus for adaptive application of release agent under all working conditions according to claim 1, characterized in that, It also includes an optical identification unit (4) for production monitoring and identification of the model of the segment mold (1). The optical identification unit (4) is electrically connected to the controller (5) and is located on the side of the designated station of the segment mold (1).

3. The apparatus for adaptive application of release agent under all working conditions according to claim 1, characterized in that, It also includes an end effector library (8), which is located within the working range of the multi-axis smearing robot arm (2). The end effector library (8) contains smearing actuators (3) of various specifications.

4. The apparatus for adaptive application of release agent under all working conditions according to claim 3, characterized in that, The end effector library (8) is provided with multiple positioning seats, each of which is equipped with a smearing actuator (3). Each positioning seat or smearing actuator (3) is provided with a readable identification code for storing its model data.

5. The apparatus for adaptive application of release agent under all working conditions according to claim 1 or 3, characterized in that, The application actuator (3) also includes a rotary drive (31) fixed at the end of the axial application robot arm (2) and a liquid supply head (32) fixed on the drive shaft of the rotary drive (31). One branch of the liquid supply pipe (68) and the recovery pipe (69) passes through the inside of the multi-axis application robot arm (2) and extends into the liquid supply head (32). The liquid supply head (32) has several liquid outlet holes. The soft application head (33) is wrapped around the outside of the liquid supply head (32).

6. The apparatus for adaptive application of release agent under all working conditions according to claim 5, characterized in that, The soft applicator (33) is a square sponge applicator.

7. The apparatus for adaptive application of release agent under all working conditions according to claim 1, characterized in that, The funnel-shaped maintenance box (7) includes an outer shell, a funnel-shaped grid set inside the outer shell, and another branch of the recovery pipe (69) extending to the bottom of the cavity of the outer shell.

8. The apparatus for adaptive application of release agent under all working conditions according to claim 1, characterized in that, The liquid storage tank (61) is also equipped with a temperature sensor (65) for detecting the temperature of the release agent and a temperature control module (64) for adjusting the temperature of the release agent. Both the temperature sensor (65) and the temperature control module (64) are electrically connected to the controller (5).

9. The apparatus for adaptive application of release agent under all working conditions according to claim 1, characterized in that, A metering pump (62) and a liquid supply valve (67) are installed on the feed pipe (63), and a negative pressure pump (66) is installed on the recovery pipe (69).

10. A control method for the apparatus according to any one of claims 1-9, characterized in that, Specifically, the following steps are included: S1, transport the tube mold (1) to the designated station on the production line. The optical recognition unit (4) identifies the model of the tube mold (1) and transmits the data to the controller (5). The controller (5) controls the multi-axis coating robot arm (2) to rotate to the end effector library (8) according to the data it receives. The corresponding coating actuator (3) is matched and installed from the end effector library (8). S2, the controller (5) controls the mold release agent storage and supply unit (6) to supply liquid to the coating execution mechanism (3) in a quantitative manner. At the same time, the controller (5) controls the multi-axis coating robot arm (2) and the rotary drive (31) to work together so that the wetted soft coating head (33) can apply the mold release agent in all directions along the inner cavity of the tube mold (1). S3, during the intermittent movement of the multi-axis coating robot arm (2), the controller (5) controls the negative pressure pump (66) to recover the residual release agent in the liquid supply head (32) through the recovery pipe (69); S4, after a single or phased application operation is completed, the controller (5) controls the multi-axis application robot arm (2) to rotate so that the soft application head (33) is temporarily placed in the funnel mesh maintenance box (7), and the residual release agent on the soft application head (33) drips and is collected in the funnel mesh maintenance box (7). S5, after all the coating operations are completed, the controller (5) controls the multi-axis coating robot arm (2) to rotate and place the soft coating head (33) in the funnel mesh maintenance box (7). Then, the controller controls the multi-axis coating robot arm (2) to press down the soft coating head (33) to squeeze out the release agent remaining inside the soft coating head (33). Then, the negative pressure pump (66) is started to recover the release agent in the funnel mesh maintenance box (7) through the recovery pipe (69).

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