JP2015116547A - Coating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide coating equipment for reducing waste coating liquid.SOLUTION: A ring-shaped coating head disposed coaxially on a surrounding of a cylindrical member 1 and coating a coating liquid to an outside surface of the cylindrical member 1 moves relatively, and has a front lip 26 on a front side of the relative movement direction and a rear lip 25 on a rear side of the relative movement direction. Distance between the rear lip 25 and a member to be coated in the vicinity of a bead liquid surface and is larger than distance between the rear lip 25 and the member to be coated in the vicinity of a discharge port 24, by forming into a taper shape or a stair shape.

Description

  The present invention relates to a coating apparatus that applies a coating liquid to a member to be coated.

  Conventionally, a to-be-coated member is moved relative to the to-be-coated member in the axial direction by moving an annular coating head arranged coaxially with the shaft of the to-be-coated member around the to-be-coated member supported in a cylindrical or columnar shape. There is a so-called ring-shaped coating device for applying a coating solution to the substrate.

  However, when the gap between the member to be coated and the coating head varies in the circumferential direction due to tolerances and eccentricity of processing accuracy, the coated film thickness may vary in the circumferential direction. If the gap between the coating heads is set large in order to reduce the variation, the coating liquid (bead) formed in a bridging manner between the coating head and the member to be coated may be cut off during the coating, so-called bead breakage may occur. .

  Therefore, the following configuration has been proposed conventionally. The coating head is composed of a rear lip disposed behind the relative movement direction of the coating head and a front lip disposed in front of the rear lip and facing the rear lip. Then, a supply port for supplying the coating liquid from between the rear lip and the front lip toward the member to be coated is provided over the entire circumference of the coating head. Furthermore, it arrange | positions so that a bead may be formed, a front lip and a rear lip contacting a coating liquid. The distance between the rear lip and the shaft at the axial position on the surface of the coating liquid in contact with the rear lip is larger than the distance between the front lip and the shaft at the axial position on the surface of the coating liquid in contact with the front lip. (Refer to Patent Document 1).

  With this configuration, it is possible to reduce variations in film thickness due to variations in the gap between the member to be coated and the coating head by securing a sufficient gap on the rear lip side while suppressing bead breakage on the front lip side.

JP 2005-152830 A

  On the other hand, the ring-shaped coating apparatus requires a cleaning process in which a coating liquid remaining on the coating head is once cleaned in preparation for coating the next coated member after coating one coated member. The coating solution remaining on the coating head after coating is washed and discarded during the cleaning process.

  With the configuration of Patent Document 1, the variation in film thickness due to the variation in gap can be reduced without causing bead breakage, but the amount of coating liquid to be cleaned increases because the amount of coating liquid used in the rear lip increases. there were.

  In view of the above, the coating apparatus of the present invention has an annular coating head disposed coaxially with the axis of the member to be coated around the member to be coated that is supported in a cylindrical or columnar shape relative to the member to be coated in the axial direction. A coating apparatus that applies a coating liquid to a member to be coated while being moved to a rear lip that is disposed rearward in the relative movement direction of the coating head, and the rear lip forward of the rear lip. A front lip disposed opposite to the coating head, and a discharge port that discharges the coating liquid from between the rear lip and the front lip over the entire circumference of the coating head, the front lip and the The rear lip forms a bead while being in contact with the coating liquid, and the rear lip and the shaft at a first position that is a position in the axial direction of the surface of the coating liquid that contacts the rear lip In the coating apparatus arranged such that the distance is larger than the distance between the front lip and the shaft at the position in the axial direction of the surface of the coating liquid in contact with the front lip, the rear lip at the first position The distance from the shaft is greater than the distance between the rear lip and the shaft at a position closer to the discharge port than the first position in the axial direction.

  According to the configuration of the present invention, it is possible to reduce the amount of the coating liquid used in the rear lip while reducing the variation in the film thickness due to the gap variation, and it is possible to reduce the discard amount of the coating liquid.

The perspective view of the ring-shaped coating device by this invention The figure which shows the coating liquid supply means of the ring-shaped coating device by this invention Detailed view of ring applicator according to the present invention (A) Enlarged sectional view showing the bead liquid level during application of the ring-shaped application head of Example 1, (b) Enlarged sectional view showing the liquid level after cleaning of the ring-shaped application head of Example 1. Flow chart of coating operation by ring-shaped coating head according to the present invention The figure which shows the application experiment result of the ring-shaped application head by Experimental example 1 The figure which shows the application | coating experiment result of the ring-shaped application | coating head by the comparative example 1. The figure which shows the application | coating experiment result of the ring-shaped application | coating head by the comparative example 2. The figure which shows the amount of beads of Experimental example 1 and Comparative examples 1 and 2. Enlarged sectional view of the ring-shaped coating head of Example 2 (A) Enlarged sectional view showing the bead liquid level at the time of application of the ring-shaped application head of Comparative Example 1, (b) Enlarged cross-sectional view showing the bead liquid level at the time of application of the ring-shaped application head of Comparative Example 2, (c) ) Enlarged sectional view showing the liquid level after cleaning of the ring-shaped coating head of Comparative Example 2

Example 1
FIG. 1 is a perspective view of a ring-shaped coating apparatus showing Embodiment 1 of the present invention. In FIG. 1, a workpiece (a member to be coated) is a cylindrical member (or a columnar member). Reference numeral 2 denotes a ring-shaped (annular) coating head which is disposed around the workpiece and coaxially with the workpiece axis and coats the coating liquid on the outer surface of the workpiece. A liquid supply tube 15 for supplying paint from a liquid supply means (not shown in the figure) is connected to the ring-shaped application head (application head) 2.

  Reference numeral 3 denotes a coating film coated on the outer surface of the cylindrical member 1 by the ring-shaped coating head 2. Reference numeral 4 denotes an elevating stage that supports the ring-shaped application head 2 while being coaxially aligned with the cylindrical member 1, and is attached to the support portion 9 via a linear guide 5. The elevating stage 4 rotates the ball screw 7 by driving a motor 6 and moves up and down at an arbitrary speed in the axial direction along the linear motion guide. Reference numeral 8 denotes a holding portion that holds the cylindrical member 1, and fixes and holds both ends of the cylindrical member 1. The ring-shaped coating head 2 and the cylindrical member 1 may be configured to move relative to each other, and may be a cylindrical member and a mechanism in which both the cylindrical member and the ring-shaped coating head move. In the present embodiment, the coating film 3 is applied from the top to the bottom of the cylindrical member 1 by moving the ring-shaped coating head 2 from the top to the bottom. The cylindrical member is supplied and set to the coating apparatus by a supply means (not shown) outside the apparatus before coating. After the application is completed, it is conveyed to a next process (not shown) outside the apparatus by a discharge means (not shown) outside the apparatus. A coating film is intermittently formed only in the coating film formation region for each part.

  FIG. 2 shows coating liquid supply means for supplying the coating liquid to the ring-shaped coating apparatus shown in FIG. 10 is, for example, a coating solution made of a solvent melt of a polymer material such as a phenol resin, and is filled in a container 11 made of glass or solvent-resistant resin. The container 11 is placed on an electromagnetic stirrer 12, and the magnetic stirrer 16 is rotated at a predetermined rotational speed by the electromagnetic stirrer 12, so that the coating liquid 10 in the container 11 is always stirred and is in a uniform state. A metering pump 13 supplies the coating liquid 10 in the container 11 to the ring-shaped coating apparatus shown in FIG. 1 at an arbitrary flow rate and flow rate. The coating liquid 10 is supplied from the container 11 to the metering pump 13 through the liquid suction tube 14, and is supplied from the metering pump 13 to the ring-shaped coating head 2 through the liquid supply tube 15. The coating liquid 10 is manufactured so that the remaining amount of the liquid is less than a certain amount and air is not sucked and supplied, and is stored in a storage (not shown) while maintaining the stability of the coating liquid. Accordingly, the container 11 is periodically supplied.

  FIG. 3 is a perspective view showing details of the cylindrical member 1, the ring-shaped coating head 2 and the coating film 3 of the ring-shaped coating apparatus shown in FIG. For ease of explanation in FIG. 3, the ring-shaped coating head 2 is a partial sectional view. 3, the same members as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  In the figure, reference numeral 21 denotes a first liquid distribution chamber formed circumferentially inside the ring-shaped coating head 2. The coating liquid supplied from the metering pump 13 via the liquid supply tube 15 is supplied to the ring-shaped coating head 2. 2 is supplied all around. Reference numeral 22 denotes a second liquid distribution chamber, which is formed in a ring shape inside the ring-shaped coating head 2 in the same manner as the first liquid distribution chamber 23. A liquid throttle channel 23 is formed between the first liquid distribution chamber 21 and the second liquid distribution chamber 22. The liquid constriction flow path 23 is also formed circumferentially inside the ring-shaped coating head 2, but its width is considerably narrower than that of the first liquid distribution chamber 21 and the second liquid distribution chamber 22. . Reference numeral 24 denotes a discharge port for applying the coating liquid 10 to the outside of the ring-shaped coating head 2. Similarly to the liquid throttle channel 23, the discharge port 24 is considerably narrower than the first liquid distribution chamber 21 and the second liquid distribution chamber 22. The liquid throttle channel 23 and the discharge port 24 function as a throttle by narrowing the width thereof, and stabilize the discharge amount of the coating liquid. Reference numeral 30 denotes a bead formed in the discharge port 24 of the ring-shaped coating head 2 by the coating liquid 10. The coating liquid 10 is discharged from the discharge port 24 and then becomes one end bead 30, and then becomes the coating film 3 by the movement of the ring-shaped coating head 2.

  FIG. 4A is a cross-sectional view passing through the axis of the cylindrical member 1, which is shown by enlarging the vicinity of the discharge port 24 of the ring-shaped coating head 2, which is indicated by a dotted circle A in FIG. 3. However, the coating film 3 is omitted in FIG. In the figure, reference numeral 25 denotes a rear lip located behind the ring-shaped coating head 2 in the relative movement direction, and reference numeral 26 denotes a front lip located in front of the relative movement direction and facing the rear lip. The rear lip has a taper shape in which the cross-sectional shape increases as the distance from the axial center of the cylindrical member 1 increases in the axial direction (backward in the relative movement direction). The angle with respect to the plane orthogonal to the axis of the tapered inclined surface is α. The minimum distance from the axial center near the discharge port of the rear lip is φD1. The distance of the front lip 26 from the axial center of the cylindrical member 1 is φD2. D1 is preferably D2 or more. The length of the rear lip taper-shaped portion in the axial direction is L, the length of the front lip 26 in the axial direction of the portion parallel to the cylindrical member 1 is M, and the rear lip 25 and the front lip. And S is the interval in the axial direction of the slit formed by. The outer diameter of the cylindrical member is φD0.

  The rear lip has a tapered shape in which the distance from the axial center of the cylindrical member 1 increases toward the upper position in the axial direction (the rear in the relative movement direction), so that the axis of the rear lip in contact with the bead The distance from is maximum at the position of the liquid surface of the bead in the axial direction. As a result, it is possible to alleviate the error variation in the distance between the cylindrical member and the ring-shaped coating head wetted part and maintain the film thickness uniformity in the circumferential direction. Further, the amount of the coating liquid used can be suppressed while ensuring the uniformity of the film thickness by reducing the amount of the bead below the liquid surface in the axial direction (forward in the relative movement direction). .

  The distance between the rear lip and the workpiece is preferably in the range of 0.1 mm to 5 mm. If it is smaller than 0.1 mm, a coating film having a uniform film thickness cannot be formed due to the influence of the surface shape of the workpiece. On the other hand, if it is larger than 5 mm, it is difficult to form a stable bead, and a coating film cannot be formed stably. The distance between the front lip and the workpiece is preferably in the range of 0.1 mm to 1 mm. If it is smaller than 0.1 mm, a coating film having a uniform film thickness cannot be formed due to the influence of the surface shape of the workpiece. On the other hand, if it is larger than 1 mm, dripping or the like occurs and it is difficult to form a stable bead. The distance between the rear lip and the front lip is preferably in the range of 0.01 mm to 5 mm. If it is smaller than 0.01 mm, it is difficult to supply the coating liquid to a smooth discharge port. If it is larger than 5 mm, it is difficult to control the supply liquid of the coating liquid, and a stable bead cannot be formed. In addition, an inclined portion that becomes a tapered slope is formed at the tip of the rear lip. It is preferable that the angle formed between the surface orthogonal to the axis of the member to be coated and the inclined portion is 30 degrees or more and 70 degrees or less. If it is less than 30 degrees, a portion parallel to the surface of the work is formed at the tip of the front lip with respect to the change in the height of the liquid level. Each length is preferably in the range of 0.1 mm to 10 mm. If it is smaller than 0.1 mm, the size of the bead to be formed becomes small, and a coating film cannot be stably formed. On the other hand, if it is larger than 10 mm, the capacity of the formed bead increases, so that it becomes difficult to form a stable bead, and a coating film cannot be formed stably.

  Next, a method for forming a coating film on the outer surface of the cylindrical member 1 by the ring coating apparatus shown in the first embodiment will be described with reference to the operation flow shown in FIG.

  First, in S1, the cylindrical member 1 is fixed and held by the holding unit 8 by a conveying means (not shown) in a state where the ring-shaped coating head 2 stands by around the holding unit 8 at the lower end which is the standby position. Next, in S2, the ring-shaped coating head rises and stops at the coating start position around the holding portion 8 at the upper end.

  Next, in S <b> 3, a predetermined amount of the coating liquid 10 is discharged from the discharge port 24 of the ring-shaped coating head 2 by the metering pump 13 and is brought into contact with the cylindrical member 1. As a result, the beads 30 are formed at positions formed by the rear lip 25, the front lip 26 and the cylindrical member 1 of the ring-shaped application head 2. In the case of a paint with low viscosity and high fluidity, if the discharge speed is too high, the coating film formed due to the inertial flow of the paint may become uneven, or the bead formation will become unstable due to the flow and liquid leakage will occur. It becomes easy. Therefore, the bead formation speed by the metering pump 13 needs to be precisely controlled. In general, the discharge of paint during bead formation contributes to the stability of the bead when it is supplied more slowly at a constant volume without causing a sudden increase in discharge. However, in view of the fluidity of the paint and the inertia weight of the paint and the dispersion in the paint, it is preferable for production to set the speed as high as possible without affecting the coating film quality.

  Next, at the same time when the ring-shaped coating head 2 starts to descend in S4-1, the coating liquid 10 is continuously discharged from the discharge port 24 in S5-1. Formation of the coating film on the coating region on the outer peripheral surface of the cylindrical member 1 is performed in synchronization with the lowering of the ring-shaped coating head 2 and the discharge of the coating solution 10. The lowering of the ring-shaped coating head 2 determines whether or not the ring-shaped coating head has reached the lower end of the coating area on the outer peripheral surface of the cylindrical member 1 in S4-2. The descent of the head 2 is stopped. At the same time, the discharge of the coating liquid 10 from the discharge port 24 determines whether or not the specified amount of discharge has been completed in S5-2, and if completed, the operation of the metering pump 13 is stopped in S5-3. The discharge of the coating liquid 10 from the discharge port 24 is stopped.

  In S6, the ring-shaped coating head 2 is lowered. It is preferable that the descending speed of the ring-shaped coating head 2 in S6 is as fast as possible in terms of apparatus setting, because the shearing speed for the remaining liquid increases and liquid draining becomes easy. By this downward movement, the ring-shaped application head 2 moves to the position of the holding portion 8 of the cylindrical member 1 to which the cylindrical member 1 can be attached and detached.

  Next, the cylindrical member 1 that has been applied in S7-1 is transported to the next step after the holding portion 8 is released. As soon as the cylindrical member 1 is removed from the holding portion 8, a new cylindrical member 1 is set in the holding portion 8.

  Further, while the cylindrical member 1 is being detached and attached in S7-1, the discharge port 24 of the ring-shaped application head 2 is washed and recovered by a cleaning mechanism (not shown) in S7-2.

  In addition, the interval (wetted part gap) between the ring-shaped application head 2 and the outer peripheral surface of the cylindrical member 1 is predetermined depending on tolerances of processing accuracy and assembly tolerances of the cylindrical member 1 and the ring-shaped application head 2. Fluctuates within the tolerance range. In the present embodiment, as shown in FIG. 4, the shape of the discharge port 24 of the coating liquid 10 maximizes the surface area of the liquid surface of the bead at the height of the liquid surface of the bead. As a result, even if the distance between the ring-shaped coating head 2 and the outer peripheral surface of the cylindrical member 1 varies within the tolerance range, no difference in film thickness occurs in the circumferential direction of the cylindrical member 1 and uniform and high accuracy. A simple coating can be formed.

The applied film thickness t is expressed by the following equation when the viscosity force η in the liquid, the density d of the coating liquid, the gravitational acceleration g, the relative speed v between the workpiece and the coating liquid, and the coefficient a.
(Formula 1) t = a (ηv / dg) ^ 1/2
Therefore, if the position of the bead liquid surface changes when the distance between the ring-shaped application head 2 and the outer peripheral surface of the cylindrical member 1 changes within the tolerance range, the relative speed between the workpiece and the application liquid changes and the film changes. The thickness will vary.

  In this embodiment, the position variation of the bead liquid level is suppressed by increasing the distance from the center of the cylindrical member axis at the position where the liquid level of the bead of the rear lip is formed. As a result, a uniform film thickness can be formed.

  Further, in this embodiment, the total bead is formed by forming the taper so that the distance between the rear lip and the shaft center decreases from the liquid surface toward the lower side in the axial direction (forward in the relative movement direction). The capacity is suppressed. As a result, it is possible to suppress the amount of the coating liquid discarded by the cleaning mechanism performed after the coating.

  FIG. 4B shows the state of the liquid level of the bead after the cleaning by the cleaning mechanism from the state of FIG. It is necessary to replenish the head with the coating liquid from the state shown in FIG. 4B after cleaning by the cleaning mechanism after the application of the workpiece to the state shown in FIG. 4A where the application of the next workpiece can be started. . That is, the difference between the amount of the coating solution in FIG. 4B and the amount of the coating solution in FIG. 4A corresponds to the amount of the coating solution discarded in one application.

(Example 2)
FIG. 10 is an enlarged cross-sectional view of a discharge portion of a ring-shaped coating apparatus showing Embodiment 2 of the present invention. The embodiment differs only in the shape of the rear lip 25 of the first embodiment. The rear lip has a stepped shape in which the cross-sectional shape has a step with a distance from the axial center upward (backward in the relative movement direction) in the axial direction. Although there are two stages in FIG. 10, the shape may be three or more stages. The distance from the axial center of the cylindrical member of the rear lip portion in the vicinity of the liquid surface of the bead is φD3, the distance in the vicinity of the discharge port is φD1, and D3 is D1 or more. The height of the step from the discharge port is the height of the step below the bead liquid surface in the axial direction (front in the relative movement direction) L1, and the height of the step having the surface on which the bead liquid surface is formed. Is L2.

  The distance between the lower step of the rear lip 25 and the cylindrical member is 0.1 mm to 2 mm, the height L1 of the lower step is 0.5 mm to 5 mm, and the distance between the upper step and the cylindrical member is 2.5 mm. The height L2 of the upper step is preferably set in the range of 6 mm to 8 mm.

  Since the rear lip satisfies D3> D1, the cross-sectional area of the liquid surface of the bead is maximized in the vicinity of the liquid surface of the bead. As a result, it is possible to alleviate the error variation in the distance between the cylindrical member and the ring-shaped coating head wetted part and to maintain the circumferential uniformity of the film thickness. Further, the amount of the coating liquid discarded can be reduced by reducing the amount of beads.

  In the first and second embodiments, the case where the workpiece is applied to the cylindrical member has been described. However, the workpiece may be a belt-like member supported by the cylindrical member.

  Next, an experiment for confirming the effect of the present invention was performed.

(Experimental example 1)
The cylindrical member was coated by the ring-shaped coating apparatus shown in Example 1. The cylindrical member 1 having a diameter φDo = 299.8 mm and a length of 320 mm was used. The minimum diameter of the rear lip 25 of the ring-shaped application head 2 from the axial center of the cylindrical member 1 is φD1 = 300 mm. The taper angle α = 45 °, the diameter of the front lip 26 from the axial center of the cylindrical member 1 is φD2 = 300 mm, and the length of the tapered portion at the tip of the rear lip 25 is L = 1 mm. The length of the portion of the front lip 26 parallel to the cylindrical member 1 is M = 1 mm, and the distance between the rear lip 25 and the front lip 26 is S = 0.5 mm. Therefore, the wetted part gap in the rear lip 25 is 1.1 mm at the maximum and 0.1 mm in the minimum, and the wetted part gap in the front lip 26 is (D2-Do) /2=0.1 mm.

  In the experiment, the cylindrical member 1 is applied to the outer peripheral surface of the cylindrical member 1 by the ring-shaped application head 2 while the cylindrical member 1 is tilted and held by moving the upper end of the cylindrical member 1 by 0.08 mm with respect to the vertical axis center. Was done. At this time, the non-contact space formed between the central axis of the cylindrical coating member surface and the lip portion of the ring-shaped coating head is the lip of the ring-shaped coating head at the coating start position at the upper end of the cylindrical coating member. The amount of eccentricity between the portion and the cylindrical member surface is about 0.08 mm. Similarly, at the application end position at the lower end of the cylindrical application member, the eccentric amount between the lip portion of the ring application head and the cylindrical member surface is about 0 mm. That is, in the process of forming the coating film from the upper end to the lower end of the cylindrical application member, the eccentricity of the non-contact space is continuously changed from 0.08 mm to 0 mm. As a result, an intentional fluctuation is given between the ring-shaped application head operating axis and the cylindrical central axis of the cylindrical member.

  And it dried by heating until the cylindrical member 1 after application | coating solidified completely. The film thickness of the outer surface of the cylindrical member 1 is measured at a plurality of locations on the entire circumference of the cylindrical member 1 at a position (measurement 1) of 50 mm from the upper end of the cylindrical member 1 (measurement 2). Measurements were made. The measurement results are shown in FIG. In FIG. 6, the horizontal axis is the phase indicating the measurement position in the circumferential direction of the cylindrical member 1, and the vertical axis is the film thickness of the coating film 3 at that time.

(Comparative Example 1)
For comparison, the same experiment was conducted using the ring-shaped coating head 2 shown in FIG. 11 (a) for the effect of the shape of the rear lip 25 of the present invention on the clearance variation during coating between the ring-shaped coating head and the cylindrical member. went. The minimum diameter of the rear lip 25 from the axial center of the cylindrical member 1 is φD1 = 300 mm, the tip of the rear lip does not have a taper shape, and the wetted part gap in the rear lip 25 is (D1−D0) /2=0.1 mm. . In Comparative Example 1, the dimensions other than the rear lip 25 are all the same as in Experimental Example 1. The measurement results are shown in FIG.

  In FIG. 6, it can be seen that the film thickness varies greatly in FIG. 7, and the film is not uniform in comparison with the substantially uniform film thickness on the entire circumference of the cylindrical member 1. That is, the rear lip 25 is tapered in such a manner that the distance from the center of the shaft increases toward the upper side in the axial direction (backward in the relative movement direction), so that it is uniform in the circumferential direction without being affected by the eccentricity of the cylindrical member 1. A simple coating film can be formed.

(Comparative Example 2)
For comparison, the same experiment was conducted using the ring-shaped coating head 2 shown in FIG. 11B for the effect of the shape of the rear lip 25 of the present invention on the clearance fluctuation during coating between the ring-shaped coating head and the cylindrical member. went. The diameter of the rear lip 25 from the axial center of the cylindrical member 1 is φD1 = 302 mm, the tip of the rear lip does not have a taper shape, and the wetted part gap in the rear lip 25 is (D1−D0) /2=1.1 mm. In Comparative Example 2, the dimensions other than the rear lip 25 are all the same as in Experimental Example 2. The measurement results are shown in FIG.

  Similar to FIG. 6, the film thickness is substantially uniform over the entire circumference of the cylindrical member 1. As in the present embodiment, the variation in film thickness can be suppressed by increasing the surface area of the bead liquid surface.

  On the other hand, FIG. 9 shows the amount of beads in Experimental Example 1, Comparative Example 1, and Comparative Example 2. In Comparative Example 2, the amount of liquid is larger than in Experimental Example 1. That is, the amount of the coating liquid discarded in the cleaning process after coating is increased.

  The amount of the coating liquid discarded in Comparative Example 2 is the difference between FIG. 11 (b) and FIG. 11 (c), whereas the amount of the coating liquid discarded in Example 1 is shown in FIG. 5 (a) and FIG. It is a difference of b) that the amount of the coating liquid discarded is smaller in Example 1 than in Comparative Example 2.

  The tip of the rear lip 25 of the first embodiment is tapered so that the diameter from the axial center of the cylindrical member 1 increases toward the upper side in the axial direction (rearward in the relative movement direction), thereby providing a uniform coating film in the circumferential direction. While maintaining, the amount of the coating liquid discarded can be suppressed.

DESCRIPTION OF SYMBOLS 1 Cylindrical member 2 Ring-shaped coating head 3 Coating film 10 Coating liquid 13 Metering pump 24 Discharge port 25 Rear lip 26 Front lip 30 Bead 31 Bead upper surface 32 Bead lower surface

Claims (4)

An annular coating head arranged coaxially with the shaft of the member to be coated around the member to be coated that is supported in a cylindrical or columnar shape is moved relative to the member to be coated in the axial direction. A coating apparatus for coating a coating liquid, wherein the coating head includes a rear lip disposed behind the relative movement direction of the coating head, and a front disposed opposite to the rear lip in front of the rear lip. A lip and a discharge port for discharging the coating liquid to the coated member from between the rear lip and the front lip over the entire circumference of the coating head, while the front lip and the rear lip are in contact with the coating liquid. The distance between the rear lip and the shaft at the first position, which is the position in the axial direction, of the surface of the coating liquid that forms a bead and contacts the rear lip is the front lip. In the coating apparatus which is arranged to be larger than the distance between the front lip and the shaft in the axial direction of the position of the surface of the coating liquid in contact with,
The distance between the rear lip and the shaft at the first position is larger than the distance between the rear lip and the shaft at a position closer to the discharge port than the first position in the axial direction. .   The coating apparatus according to claim 1, wherein a cross-sectional shape passing through the shaft of the rear lip is a tapered shape.   The coating apparatus according to claim 1, wherein a cross-sectional shape passing through the axis of the rear lip is a step shape.   The coating apparatus according to claim 2, wherein, in a cross section passing through the axis of the rear lip, an angle formed by the inclined surface of the rear lip with respect to a plane orthogonal to the axis is 30 degrees or more and 70 degrees or less.

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