JP2007252976A - Coating head and coating film forming apparatus provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating head having a simple structure and capable of preventing the leakage of a coating material in setting-up and forming the coating film having a uniform thickness and a coating film forming apparatus provided with the coating head. <P>SOLUTION: The coating film forming apparatus 1 is provided with a holding part, a moving part 12 and the coating head 13. The holding part holds a base body 4 in a state that a shaft center P is kept parallel to the vertical direction. The coating head 13 is provided with a head main body 37 which is formed annular box-like, houses the coating material 7, has opening parts over the whole inner peripheral surface and applies the coating material 7 on the outer peripheral surface 4c of the base body 4 by passing the base body 4 through the inside, a liquid level detecting sensor 53 for measuring the height of the liquid level 7a of the coating material 7 in the head main body 37, a volume changing part 14 capable of changing the volume of the coating material 7 to be housed in the head main body 37 and a controller 18 for properly changing the height of the liquid level 7a of the coating material 7 in the head main body 37 by controlling the volume changing part 14 based on the height of the liquid level 7a measured by the liquid level detecting sensor 53. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a coating head that forms a coating film by coating a coating on a cylindrical outer peripheral surface of an object to be coated, and a coating film forming apparatus including the coating head. For example, in an image forming apparatus employing an electrophotographic system such as a PPC (plain paper copier), LBP (laser beam printer), facsimile, etc., a fixing member (fixing) that fixes an unfixed toner image on the transfer paper by heating and pressing. The present invention relates to a coating head suitable for forming a release layer and a primer layer of a roller and a fixing belt, and a coating film forming apparatus including the coating head.

  In an image forming apparatus such as a copying machine and a printer based on the principle of electrophotography, a fixing process is performed in which a transfer paper is narrowed and toner is melted by heat and fixed on the transfer paper. In recent years, parts (fixing roller or fixing belt) used in the fixing process include an elastic layer (having a thickness of about 100 μm to 300 μm) made of a heat-resistant rubber such as silicone rubber on a base, and an elastic layer on the elastic layer. The formed primer layer, a release layer (thickness of about 20 μm to 30 μm) made of a fluororesin, and the like are sequentially formed.

  As a method for forming the release layer described above, spray coating is generally used in which spraying is applied by spraying. However, spraying has a coating efficiency of about 20% to 30% (the proportion of paint that actually adheres to the object to be coated), and about 70% to 80% of the paint used for painting is used. Therefore, the efficiency of the paint is very poor, and a very large amount of paint is required. Also, fluororesin is difficult to paint, and spraying a coating of 20 μm to 30 μm at a time will cause surface defects such as repelling the paint, so how many thin layers are needed to form the release layer described above In addition, it was necessary to paint repeatedly, and the working time tended to be longer.

  On the other hand, dip coating is conceivable as a method of compensating for these drawbacks. This dip coating is a system in which the coating object is formed by immersing the object in a liquid tank containing the paint and pulling it up to form a coating film. There is little waste of paint at the time. However, this dip coating requires a liquid amount that allows the object to be completely immersed in the liquid tank, so that the parts used in the fixing process of the image forming apparatus described above are completely immersed in the axial direction. Has a problem that a liquid tank having a depth of about 500 mm is required, and a large amount of paint is required.

A coating apparatus (see, for example, Patent Documents 1 to 3) as a coating film forming apparatus that avoids all of the above problems has been proposed. This type of coating apparatus realizes dip coating with a small amount of paint by sealing an application head as a liquid tank and moving it relative to the object to be coated. The above-described coating apparatuses disclosed in Patent Documents 1 to 3 can continuously coat a plurality of objects to be coated arranged coaxially, and, of course, coat the objects to be coated one by one. Is also possible.
JP-A-8-23698 JP 2004-279918 A Japanese Patent Laid-Open No. 2004-290853

  When coating the objects to be coated one by one using the coating apparatus disclosed in Patent Documents 1 to 3, if the objects to be coated are removed from the coating head, the paint leaks from the coating head. In order to prevent this, a mask having a thickness equivalent to that of the above-described coating film is provided on the holding portion that holds the object to be coated. In this case, since the paint adheres to the mask, it is necessary to clean the mask every time it is applied, and there is a problem that the number of steps required for painting the object to be coated increases.

  Moreover, in the coating apparatus shown by patent document 1 thru | or 3, since the volume in a coating head is small, the liquid level of the coating material in this coating head falls during coating, and the thickness of a coating film is to-be-coated object. It will be different in the axial direction. In order to solve this type of problem, a pump for feeding the paint in the coating head, a pump for sending the paint in the coating head back to an external tank, etc. are provided, and the paint is applied between the coating head and the external tank. A mechanism to circulate is required. Thus, in order to make the thickness of the coating film uniform in the axial direction of the object to be coated, there has been a problem that the coating apparatus is increased in size.

  Accordingly, an object of the present invention is to provide a coating head capable of preventing paint leakage during setup and forming a uniform thickness coating film with a simple configuration, and a coating film forming apparatus including the coating head. That is.

  In order to solve the above-described problem, the coating head according to claim 1 moves relative to the object to be coated along the axis of the object to be coated, and has a cylindrical outer peripheral surface of the object to be coated. In the coating head for applying a coating material to form a coating film, the coating head is formed in an annular box shape and contains the coating material, and an inner circumferential surface is provided with openings over the entire circumference. A head body that passes the object to be coated inward and applies the paint to the outer peripheral surface of the object to be coated; a measuring unit that measures the height of the liquid level of the paint in the head body; A volume changing means capable of changing the volume in which the paint can be stored, and a volume of the paint in the head body by controlling the volume changing means based on the height of the liquid level measured by the measuring means. And a control unit that changes the height of the surface as appropriate.

  The coating head according to claim 2 is the coating head according to claim 1, wherein the control unit has a constant height of the liquid surface measured by the measuring unit during coating of the paint. It is a control part which controls the said volume change means.

  The coating head according to claim 3 is the coating head according to claim 1 or 2, wherein the volume changing means enters the head body or moves away from the head body. An intruder provided movably with respect to the intruder, and an intruder moving unit that moves the intruder into the head body or moves away from the head body according to a command from the control unit, It is characterized by having.

  A coating head according to a fourth aspect is the coating head according to the third aspect, wherein a refrigerant circulation part that circulates the refrigerant provided in the intruder and heat that keeps the temperature of the refrigerant in the refrigerant circulation part constant. And an exchange.

  A coating head according to a fifth aspect is the coating head according to the first or second aspect, wherein the volume changing means is positioned in the head main body and expands when a pressurized fluid is supplied. An elastic bag made of an elastic material, and a pressure changing unit that changes the pressure of the pressurized fluid supplied into the elastic bag in accordance with a command from the control unit.

  The coating head according to claim 6 is the coating head according to claim 1 or 2, wherein the volume changing means enters the head body or moves away from the head body. A magnet that is movable relative to the head, an electromagnet that is attached to the head body relative to the magnet and that generates a magnetic force having a polarity different from that of the magnet when a voltage is applied thereto, and And a voltage changing unit that changes the voltage applied to the electromagnet as instructed.

  The coating head according to claim 7 is the coating head according to any one of claims 1 to 6, wherein the bottom surface of the head body gradually rises toward the center of the head body. And an inclined surface that is inclined with respect to the axis is provided.

  The coating film forming apparatus according to claim 8, wherein a coating film is formed by applying a paint to a cylindrical outer peripheral surface of an object to be coated to form a coating film, and the outer peripheral surface is exposed and the object to be coated is formed. A holding portion for holding the object to be coated in a state in which the shaft core is parallel to the vertical direction, and the paint is accommodated and moved relative to the object to be coated. An application head that applies to the outer peripheral surface of the substrate, and a moving unit that relatively moves the holding unit and the application head along the axis. The coating head according to any one of the above is provided.

  According to the coating head of the first aspect, the height of the liquid level of the paint in the head main body can be appropriately changed by appropriately changing the volume in the head main body by the volume changing means. The liquid level of the paint can be lowered, and the volume in the head body can be gradually reduced by the volume changing means when applying the object to be coated, so that the liquid level of the paint can be kept constant. Therefore, it is possible to prevent paint leakage at the time of setup with a simple configuration of providing a volume changing means, so that it is not necessary to use a mask when attaching or detaching the object to be coated, and the required man-hours at the time of setup can be reduced and uniform thickness The coating film can be reliably formed.

  According to the application head described in claim 2, since the control unit controls the volume changing means so as to keep the liquid level of the paint in the head body constant when applying the object to be coated, A coating film can be formed reliably.

  According to the coating head according to claim 3, since the intruder moving unit moves the intruder into and out of the head main body according to a command from the control unit, a minute change in the liquid level of the paint in the head main body is achieved. Accordingly, the penetrator can be taken in and out of the head main body, so that the liquid level of the paint in the head main body can be reliably kept constant. Therefore, a coating film having a uniform thickness can be more reliably formed.

  According to the coating head of the fourth aspect, since the refrigerant circulation portion that flows the refrigerant provided in the intruder and the heat exchanger that maintains the refrigerant at a constant temperature are provided, unevenness in the viscosity of the paint is caused. Even if the paint is stirred to prevent the temperature of the paint from rising and the viscosity of the paint from changing, it is possible to form a highly accurate coating film.

  According to the coating head of the fifth aspect, the pressure changing unit changes the pressure of the pressurized fluid in the elastic bag according to a command from the control unit, so that the liquid level of the paint in the head body is fine. The elastic bag can be inflated following the change, and therefore, the liquid level of the paint in the head body can be reliably kept constant. Therefore, a coating film having a uniform thickness can be more reliably formed.

  According to the coating head of the sixth aspect, the magnetic force generated by the electromagnet is changed in accordance with a command from the control unit to change the amount of the magnet entering the head main body. The magnet can be taken in and out of the head body while following a minute change in the surface, and therefore the liquid level in the head body can be reliably kept constant. Therefore, a coating film having a uniform thickness can be more reliably formed.

  According to the coating head according to claim 7, since the bottom surface of the head main body becomes lower concentrically from the object to be coated, the paint is transferred to the head when the liquid level of the paint in the head main body is lowered after the coating is finished. It will surely return to the inside of the body, so even if the object to be painted is pulled out from the inside of the head body, the paint will not overflow from the head body, so there is no need to seal the head body with a mask etc. It becomes possible to paint. Accordingly, since it is not necessary to clean the mask, it is possible to prevent an increase in the number of man-hours required for the setup work.

  According to the coating film forming apparatus of the eighth aspect, since the coating head described above is provided, it is possible to prevent leakage of the paint at the time of setup with a simple configuration of providing the volume changing means, and to have a uniform thickness. A coating film can be formed reliably.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 4, 11 and 12. 1 is a configuration diagram of a coating film forming apparatus according to an embodiment of the present invention, and FIGS. 2 to 4 are cross-sectional views of a coating head of the coating film forming apparatus shown in FIG.

  In the coating film forming apparatus 1 shown in FIG. 1, a primer layer 3 (shown in FIG. 12) and an elastic layer 5 of a fixing belt 2 (shown in FIG. 11) constituting an image forming apparatus such as a copying machine are formed. This is an apparatus for forming a release layer 6 as a coating film on a substrate 4 as an object to be coated.

  The fixing belt 2 is formed in an endless shape as shown in FIG. As shown in FIG. 12, the fixing belt 2 includes an endless belt-like base 4 made of polyimide, Ni, etc., a primer layer 3, an elastic layer 5 made of heat-resistant rubber such as silicone rubber, and a primer. The layer 3 and the release layer 6 made of a fluororesin are sequentially laminated. The elastic layer 5 has a thickness T of about 100 to 300 μm. The release layer 6 has a thickness of about 20 to 30 μm. The thickness of the substrate 4 as the object to be coated before the release layer 6 described above is combined with the primer layer 3 described above is about 200 μm to 400 μm. That is, the base 4 described above is relatively thin and easy to deform as a whole.

  In addition, the primer layer 3, the elastic layer 5, and the release layer 6 have one end in the width direction of the base 4 (upper end when a coating 7 described later is applied by the coating film forming apparatus 1) 4 a and the base 4. , And the other end in the width direction (lower end when the coating material 7 is applied by the coating film forming apparatus 1) 4b. The above-described fixing belt 2 is heated to press the toner against the transfer paper and fix the toner onto the transfer paper.

  The coating film forming apparatus 1 has the above-described fluorine on the outer surface of the substrate 4 (corresponding to the object to be coated in the claims) on which the primer layer 3 and the elastic layer 5 are formed, that is, on the primer layer 3 described above. A coating layer 7 (shown in FIG. 2) containing a resin and a known solvent is applied to form the release layer 6 described above.

  As shown in FIG. 1, the coating film forming apparatus 1 includes an apparatus main body 10, a holding unit 11, a moving unit 12, and a coating head 13.

  The apparatus main body 10 is installed on a factory floor or the like. The apparatus main body 10 includes a plurality of horizontal plates 19, a single vertical plate 20, and a plurality of connecting columns 21. Three horizontal plates 19 are provided. As for the horizontal plate 19, both surfaces are arrange | positioned in parallel with the horizontal direction, respectively. The horizontal plates 19 are arranged at intervals from each other along the vertical direction. Both surfaces of the vertical plate 20 are arranged in parallel with the vertical direction. The vertical plate 20 connects the lowermost horizontal plate 19 and the uppermost horizontal plate 19. The horizontal plate 19 located at the center is connected to the central portion of the vertical plate 20. The connecting column 21 is formed in a quadrangular column shape and connects a plurality of horizontal plates 19.

  As shown in FIG. 1, the holding unit 11 includes a mandrel 22, one holding rod 24, and one chuck cylinder 25. The mandrel 22 is press-fitted into the aforementioned base 4 and supports the base 4 from the inside. Further, the mandrel 22 is formed sufficiently longer than the base 4.

  The holding rod 24 is formed in a columnar shape, and is fixed to the horizontal plate 19 in a state of being erected from the horizontal plate 19 disposed at the center of the three horizontal plates 19. The holding rod 24 is formed so that its axial center is arranged in parallel with the vertical direction, and its upper end portion gradually tapers as it goes upward.

  The chuck cylinder 25 includes a cylinder body 30 and a rod 31 that can protrude and retract from the cylinder body 30. The cylinder body 30 is attached to the uppermost horizontal plate 19 with the rod 31 extending downward along the vertical direction. The rod 31 is formed in a columnar shape, and its axial center is arranged in parallel with the vertical direction, and its lower end portion is gradually tapered as it goes downward. The rod 31 is disposed along the vertical direction at a position facing the holding rod 24 with a space (a position coaxial with the holding rod 24).

  The holding rod 24 and the chuck cylinder 25 sandwich the mandrel 22 between each other as the rod 31 of the chuck cylinder 25 extends.

  In the holding unit 11 described above, the mandrel 22 is press-fitted into the base 4, the base 4 and the mandrel 22 are arranged between the holding rod 24 and the chuck cylinder 25, and the rod 31 of the chuck cylinder 25 is placed. Elongate. The holding unit 11 holds the base body 4 with the mandrel 22 sandwiched between the holding rod 24 and the rod 31 of the chuck cylinder 25.

  When the holding unit 11 holds the base body 4, the axis P of the base body 4 (indicated by a one-dot chain line in FIG. 1) is parallel to the vertical direction. When the holding unit 11 holds the base body 4, the outer peripheral surface 4 c of the base body 4 has a cylindrical surface shape (a cross-sectional shape in a direction perpendicular to the axis P is an arc shape). As described above, the holding unit 11 holds the base body 4 in a state where the axis P is parallel to the vertical direction. The holding unit 11 extends the rod 31 of the chuck cylinder 25 to hold the base 4 via the mandrel 22 and the like, and reduces the rod 31 of the chuck cylinder 25 and passes the mandrel 22 and the like. The base 4 is detachable. Furthermore, when holding the base body 4, the holding portion 11 naturally exposes the outer peripheral surface 4 c of the base body 4.

  As shown in FIGS. 2 to 4, the moving unit 12 includes a linear actuator 32 and a linear encoder 33 as a moving speed detecting unit. The linear actuator 32 includes a rail attached to the vertical plate 20 with its longitudinal direction parallel to the vertical direction, and a slider that moves relative to the rail along the longitudinal direction of the rail, that is, the vertical direction. A support base 34 to be described later is attached to the slider.

  The linear actuator 32, that is, the moving unit 12 moves the head body 37 up and down. That is, the linear actuator 32, that is, the moving unit 12 relatively moves the holding unit 11 and the head main body 37 along the axis P. The linear encoder 33 detects the moving speed of the slider, that is, the head body 37 described above, and outputs information corresponding to the moving speed to the control device 18.

  As shown in FIGS. 2 to 4, the coating head 13 includes a support base 34, a moving support unit 35, a head body 37, a liquid level detection sensor 53 as a measurement unit, and a temperature sensor 53 as a temperature measurement unit. And a volume changing unit 14 as a volume changing unit, a paint supply unit 15, a cooling unit 16, and a control device 18 as a control unit.

  The support base 34 is formed in a flat plate shape. The support base 34 is attached to the slider of the linear actuator 32. Both surfaces of the support base 34 are arranged in parallel with the horizontal direction. That is, the surface of the support base 34 is formed flat along a direction orthogonal to the axis P. The support base 34 supports the head main body 37 via the ball roller 36. The support base 34 is disposed below the head body 37.

  The movement support unit 35 includes a plurality of ball rollers 36. The ball roller 36 includes a roller main body 38 and a ball 39 that is provided to roll freely at the tip (lower end) of the roller main body 38. The roller body 38 is formed in a cylindrical shape, and is attached to an outer edge portion of a bottom plate portion 45 of a body portion 43 described later of the head body 37. The roller body 38 is arranged such that its axis is parallel to the axis P described above, that is, the vertical direction. The ball 39 is formed in a spherical shape and is provided at the lower end of the roller body 38, that is, at the end near the support base 34. Further, the balls 39 are arranged on the surface of the support base 34 and can roll on the surface of the support base 34. The movement support part 35 supports the head main body 37 movably along the direction orthogonal to the axis P described above on the support base 34 by the balls 39 rolling on the support base 34.

  As shown in FIGS. 2 to 4, the head main body 37 includes a main body 43 and a lid 44. The main body 43 includes an annular bottom plate 45, a cylindrical outer peripheral wall 46 erected from the radial center of the bottom plate 45, and an inner peripheral wall 47 erected from the entire inner edge of the bottom plate 45. It has. The bottom plate portion 45, the outer peripheral wall 46, and the inner peripheral wall 47 are arranged coaxially with each other. The inner diameter of the bottom plate portion 45, that is, the main body portion 43 is larger than the outer diameter of the base body 4. The height of the outer peripheral wall 46 from the bottom plate portion 45 is higher than the height of the inner peripheral wall 47 from the bottom plate portion 45.

  On the inner surface of the inner peripheral wall 47, an inclined surface 48 that is gradually inclined toward the inner side of the bottom plate portion 45 as it goes upward from the bottom plate portion 45 is formed over the entire circumference. The inclined surface 48 is gradually inclined upward with respect to the axis P described above toward the center of the head body 37. The surface of the bottom plate portion 45 and the inner surface of the inner peripheral wall 47 form the bottom surface of the head body 37 described in the claims. That is, an inclined surface 48 is provided on the bottom surface of the head body 37. Due to the inclined surface 48, the bottom surface of the head main body 37 becomes lower as it moves away from the base body 4 in a concentric manner.

  The lid body 44 includes an annular lid body 49 and a partition wall 50. The lid main body 49 is formed so that the outer diameter is substantially equal to the bottom plate portion 45 of the main body portion 43 and the inner diameter is larger than that of the bottom plate portion 45 of the main body portion 43. The lid main body 49, that is, the lid body 44 is attached to the main body portion 43 such that the outer edge portion thereof overlaps the outer peripheral wall 46 of the main body portion 43. The lid 44 prevents the solvent of the paint on the main body 43 from volatilizing and prevents foreign matters such as dust from entering the paint 7 in the main body 43. The inner edge of the lid body 49 is spaced from the inner peripheral wall 47. For this reason, the head main body 37 has an upper end portion of the inner peripheral surface cut out over the entire circumference. That is, the head main body 37 is provided with an opening that communicates the inside and the outside at the upper end of the inner peripheral surface thereof.

  The partition wall 50 is formed in a cylindrical shape and is arranged coaxially with the lid body 44. The partition wall 50 is erected from the central portion between the inner edge and the outer edge of the lid body 49 toward the bottom plate portion 45. The height of the partition wall 50 from the lid body 49 is lower than the height of the outer peripheral wall 46 from the bottom plate portion 45. For this reason, the partition wall 50 is opposed to the bottom plate portion 45 of the main body portion 43 with a space therebetween. The partition wall 50 divides the space 51 in the head main body 37 surrounded by the main body 43 and the lid main body 49 into two. The partition wall 50 interferes with bubbles generated in the paint 7 in the head body 37 when supplied by the paint supply unit 15, and the bubbles move to the base 4 side and adhere to the base 4. To prevent.

  The head main body 37 described above accommodates the above-described paint 7 in the above-described space 51 surrounded between the main body portion 43 and the lid body 44. The head body 37 is supplied with the paint 7 from the paint supply unit 15. A seal member 52 is attached to the inner surface of the inner peripheral wall 47 of the main body portion 43 of the head main body 37, that is, the inner peripheral surface of the head main body 37 over the entire circumference. The seal member 52 is made of an elastically deformable synthetic resin such as rubber and is formed in an annular shape. The seal member 52 has a constant thickness in the circumferential direction. The seal member 52 is disposed coaxially with the head body 37. The inner diameter of the seal member 52 in a neutral state where the seal member 52 is not elastically deformed is smaller than the outer diameter of the base body 4.

  For this reason, the seal member 52 abuts on the base body 4 passed through the head main body 37 and is elastically deformed to a state where the base body 4 can be passed. When elastically deforming as described above, the seal member 52 presses the outer peripheral surface 4c of the base body 4 inward along the radial direction of the base body 4, and keeps the space between the outer peripheral surface 4c of the base body 4 watertight. That is, the seal member 52 prevents the paint 7 in the head main body 37 from leaking out of the head main body 37 from between the base member 4. Since the seal member 52 itself is formed in an annular shape, when the head main body 37 is movable with respect to the support base 34, the force that presses the outer peripheral surface 4 c of the base 4 of the seal member 52 is increased. It becomes uniform in the circumferential direction.

  The head main body 37 passes the base body 4 through the main body portion 43 so that the outer peripheral surface 4c of the base body 4 is immersed in the paint 7 of the main body portion 43, and as shown by parallel oblique lines in FIGS. A release layer 6 as a coating film is formed on the outer peripheral surface 4c.

  The liquid level detection sensor 53 is attached to the lid main body 49 of the lid body 44, and irradiates the liquid level 7a of the coating material 7 accommodated in the head main body 37 with ultrasonic waves or the like, thereby increasing the height of the liquid level 7a. Measure the thickness. The liquid level detection sensor 53 outputs information indicating the height of the liquid level 7 a of the paint 7 in the head body 37 to the control device 18.

  The temperature sensor 53 is attached to the inner surface of the main body 43 and measures the temperature of the paint 7 accommodated in the head main body 37. The temperature sensor 53 outputs information indicating the temperature of the paint 7 in the head body 37 to the control device 18.

  As illustrated in FIGS. 2 to 4, the volume changing unit 14 includes an intruder 40 and a linear actuator 41 as an intruder moving unit. The intruder 40 is formed in an annular shape. The outer diameter of the penetrator 40 is formed smaller than the inner diameter of the lid main body 49 of the lid body 44. The inner diameter of the intruder 40 is formed larger than the outer diameter of the base body 4. The intruder 40 is disposed coaxially with the base body 4 and the head body 37 and is movably provided along the axis P with respect to the lid body 49, that is, the head body 37.

  The penetrator 40 is movable through the inner edge of the lid main body 49 into the head main body 37 and in a direction away from the head main body 37. In addition, a second inclined surface 42 that is parallel (substantially parallel) to the inclined surface 48 is provided on the inner edge of the intruder 40 that faces the inclined surface 48. The penetrator 40 allows the paint 7 to move from the inner peripheral surface of the head body 37 toward the base body 4 even if the penetrator 40 penetrates into the back of the head body 37 by the second inclined surface 42.

  The linear actuator 41 includes a rail erected from the support base 34 in a state where the longitudinal direction is parallel to the vertical direction, and a slider that moves relative to the rail along the longitudinal direction of the rail, that is, the vertical direction. The intruder 40 described above is attached to the slider. The linear actuator 41 causes the intruder 40 to enter the head main body 37 or move in a direction to leave the head main body 37 in accordance with a command from the control device 18.

  The volume changing unit 14 lowers the penetrator 40 by the linear actuator 41 and increases the penetrating amount of the penetrator 40 into the head main body 37 (the mass of the penetrating portion), whereby the paint 7 in the head main body 37 is increased. Is reduced (the amount of paint 7 that can be stored in the head body 37). Further, the volume changing unit 14 is configured such that the linear actuator 41 raises the penetrator 40 to reduce or eliminate the penetrating amount of the penetrator 40 into the head main body 37 (the mass of the penetrating portion). The volume (the amount of the paint 7 that can be accommodated in the head body 37) that can accommodate the paint 7 inside is increased. Thus, the volume changing unit 14 can change the volume in which the paint 7 in the head main body 37 can be accommodated by the linear actuator 41 moving the intruder 40 up and down.

  As shown in FIG. 1, the paint supply unit 15 includes a paint tank 67 as a storage container, a stirring motor 68, a liquid feed pump (not shown), a viscometer 69 as a viscosity measurement unit, and a supply pipe 70 ( 2). The paint tank 67 is installed on the lowermost horizontal plate 19 of the apparatus main body 10. The paint tank 67 stores the paint 7 described above. The stirring motor 68 is fixed to the paint tank 67, and an impeller is attached to an output shaft positioned in the paint tank 67. The agitation motor 68 agitates the paint 7 in the paint tank 67 to prevent unevenness in the viscosity of the paint 7.

  The liquid feed pump feeds the paint 7 in the paint tank 67 into the main body 43 of the head main body 37 through the supply pipe 70. The viscometer 69 is provided in the paint tank 67 and can measure the viscosity of the paint 7 in the paint tank 67. The viscometer 69 outputs information indicating the viscosity of the paint 7 in the paint tank 67 to the control device 18. The supply pipe 70 connects the paint tank 67 and the main body 43 of the head main body 37.

  The above-described coating material supply unit 15 supplies the above-described coating material 7 into the head body 37 by the liquid feeding pump sending the coating material 7 in the coating material tank 67 into the body portion 43 of the head body 37.

  The cooling unit 16 includes a refrigerant circulation passage 71 (shown in FIG. 2) as a refrigerant circulation unit, and a cooling water circulation device 72 (shown in FIG. 1) as a heat exchanger. The passage 71 is a space formed in the intruder 40, and is provided on the entire circumference of the intruder 40 and has a planar shape in an annular shape. The passage 71 circulates the water into the intruder 40 through water as a refrigerant. The passage 71 circulates water to cool or heat the paint in the head main body 37 via the intruder 40.

  The cooling water circulation device 72 is installed on the lowermost horizontal plate 19. The cooling water circulation device 72 temporarily accumulates the water in the passage 71, sympathizes the heat of the water with external heat, and cools or heats the water to a desired temperature. Then, the cooling water circulation device 72 sends out the cooled or heated water into the passage 71 again. Thus, the cooling water circulation device 72 keeps the temperature of the paint 7 in the head body 37 as described above by cooling or heating the paint 7 in the head body 37 by keeping the temperature of the water as the refrigerant in the passage 71 constant. .

  The control device 18 is a computer including a known RAM, ROM, CPU, and the like. As shown in FIG. 1, the control device 18 is attached to both the upper end portion of the vertical plate 20 and the uppermost horizontal plate 19. The control device 18 is connected to the holding unit 11, the moving unit 12, the volume changing unit 14, the paint supply unit 15, the cooling unit 16, and the like, and controls these to apply the coating head 13 and the coating film formation. Controls the entire apparatus 1. That is, information from the linear encoder 33 of the moving unit 20 and information from the liquid level detection sensor 53 are input to the control device 18, and information from the linear encoder 33 and information from the liquid level detection sensor 53 are also input. Each part is controlled based on the above.

  A start switch 75 and various operation switches 76 are attached to the control device 18. The start switch 75 is used to switch the entire coating film forming apparatus 1 on and off. The operation switch 76 is used for operating the entire coating film forming apparatus 1. The control device 18 operates the entire coating film forming apparatus 1 with the operation switch 76.

  When the release layer 6 is formed on the base 4, the control device 18 operates each part such as the coating head 13 as follows. First, the control device 18 reduces the rod 31 of the chuck cylinder 25 and raises the penetrator 40 to the linear actuator 41 so that a predetermined amount (a necessary amount for one application) is applied to the paint supply unit 15. While supplying the paint 7 into the head main body 37, the head main body 37 is moved to the uppermost position by the moving unit 12. At this time, the liquid level 7a and the intruder 40 are not in contact with each other (with a gap), and the paint 7 is supplied and the intruder 40 is raised so that the liquid level 7a is lower than the inner peripheral wall 47 (head body 37). Move in the direction of leaving). At this time, since the liquid surface 7 a is positioned below the inner peripheral wall 47, the paint 7 does not leak from the inner peripheral surface of the head body 37.

  With the head main body 37 positioned at the uppermost position, the base body 4 into which the mandrel 22 is press-fitted is positioned between the holding rod 24 and the rod 31 of the chuck cylinder 25. When the base 4 and the mandrel 22 are positioned between the holding rod 24 and the rod 31 of the chuck cylinder 25, the control device 18 extends the rod 31 of the chuck cylinder 25. Then, with the mandrel 22 and the like sandwiched between the holding rod 24 and the rod 31 of the chuck cylinder 25, the holding unit 11 holds the base body 4 with the shaft core parallel to the vertical direction as shown in FIG.

  The control device 18 gradually lowers the application head 13 to the moving unit 12 and causes the linear actuator 41 to intrude the intruder 40 into the head main body 37 so that the liquid level 7a is positioned above the inner peripheral wall 47. . Then, as shown in FIG. 3, the coating 7 is applied to the outer peripheral surface 4c of the base body 4 in order from the upper end 4a to the lower end 4b, the coating 7 is dried, and the coating 7 is dripped. Instead, the release layer 6 is formed. The controller 18 gradually moves the penetrator 40 into the head body 37 so that the height of the liquid level 7a measured by the liquid level detection sensor 53 is constant during application of the paint 7 to the outer peripheral surface 4c of the base 4. The linear actuator 41 of the volume changing unit 14 is controlled so as to enter.

  When the control device 18 determines that the head main body 37 is positioned at the lowest position based on the information from the linear encoder 33, the control device 18 stops the moving unit 12 and the linear actuator of the volume changing unit 14 as shown in FIG. The intruder 40 is raised to 41 and the intruder 40 is detached from the head main body 37. At this time, since the paint 7 in the head main body 37 of the application head 13 is naturally reduced from that before application, the liquid level 7 a is much lower than the inner peripheral wall 47.

  Then, the control device 18 reduces the rod 31 of the chuck cylinder 25. Then, after the base body 4 on which the release layer 6 is formed and the mandrel 22 supporting the base body 4 are removed, the control device 18 applies the paint 7 to the paint supply unit 15 while raising the head main body 37. Then, the substrate 4 is supplied to the substrate 37, and the substrate 4 is painted in the same manner as described above. Further, the control device 18 keeps the temperature of the water 7 as the refrigerant constant in the cooling unit 16 described above, and keeps the temperature of the paint 7 in the head main body 37 constant described above.

  As described above, when the base body 4 is attached or detached, the control device 18 causes the volume changing unit 14 to increase the volume in the head main body 37 and lower the liquid level 7 a of the paint 7 in the head main body 37. When the release layer 6 is formed on the substrate 4, the control device 18 gradually decreases the volume in the head body 37 to the volume changing unit 14 as the applied area increases, so that the paint 7 in the head body 37. The liquid level 7a is kept at a certain height at which the outer peripheral surface 4c of the substrate 4 can be applied. Thus, the control device 18 controls the volume changing unit 14 to appropriately change the height of the liquid surface 7a of the paint 7 in the head body 37.

  According to the present embodiment, the height of the liquid surface 7a of the paint 7 in the head body 37 can be changed as appropriate by causing the volume changing unit 14 to change the volume in the head body 37 as appropriate. At the time of setup, the height of the liquid surface 7a of the paint 7 in the head main body 37 can be lowered, and at the time of applying the paint 7 on the base body 4, the volume in the head main body 37 is gradually reduced by the volume changing unit 14. 7, the height of the liquid surface 7a can be kept constant. Therefore, it is possible to prevent the paint 7 from leaking at the time of setup for attaching and detaching the base body 4 and to form the release layer 6 as a coating film with a uniform thickness with a simple configuration in which the volume changing portion 14 is provided. it can.

  Since the control device 18 controls the volume changing unit 14 so as to keep the liquid level 7a of the paint 7 in the head body 37 constant when the paint 7 is applied to the base body 4, the paint is applied when the paint 7 is applied to the base body 4. 7, the height of the liquid surface 7a can be kept constant. Therefore, it is possible to reliably form the release layer 6 as a coating film having a uniform thickness.

  Since the linear actuator 41 as an intruder moving unit moves the intruder 40 in and out of the head main body 37 in accordance with a command from the control device 18, the height of the liquid surface 7 a of the paint 7 in the head main body 37 is minutely changed. Accordingly, the intruder 40 can be taken in and out of the head main body 37, so that the liquid level 7a of the paint 7 in the head main body 37 can be reliably kept constant. Therefore, the release layer 6 as a coating film having a uniform thickness can be more reliably formed.

  In order to prevent unevenness in the viscosity of the coating material 7, since the passage 71 for flowing water as a refrigerant provided in the intruder 40 and the cooling water circulation device 72 for keeping the water as the refrigerant at a constant temperature are provided. Even if the coating material 7 is stirred, it is possible to prevent the viscosity of the coating material 7 from changing due to an increase in the temperature of the coating material 7. For this purpose, the release layer 6 is formed as a highly accurate coating film. be able to.

  Since the bottom surface of the head body 37 becomes lower concentrically from the base body 4, the coating 7 is surely returned to the head body 37 when the liquid level 7a of the coating 7 in the head body 37 is lowered after the coating is completed. Even if the base body 4 is removed from the inside of the head main body 37, the paint 7 does not overflow from the head main body 37, so that it is not necessary to seal the head main body 37 with a mask or the like, so that the maskless coating can be performed. Become. Accordingly, since it is not necessary to clean the mask, it is possible to prevent an increase in the number of man-hours required for the setup work.

  Since the moving support portion 35 allows the head main body 37 to move in the direction perpendicular to the axis P with respect to the support base 34, and the seal member 52 that is elastically deformable is provided on the entire inner periphery of the head main body 37. The head main body 37 is positioned at a position where the elastic restoring force of the seal member 52 becomes uniform in the circumferential direction by the elastic restoring force of the seal member 52. Therefore, the force by which the sealing member 52 presses the substrate 4 as the object to be coated can be uniform in the circumferential direction, and the pressing force of the sealing member 52 can be prevented from being concentrated on a part. Even if the base 4 is thin, the base 4 can be prevented from being deformed.

  Due to the elastic restoring force of the sealing member 52 described above, the distance between the head main body 37 and the base body 4 becomes uniform in the circumferential direction, so that the release layer 6 having a constant thickness can be formed on the outer peripheral surface 4c of the base body 4. Therefore, the release layer 6 having a certain thickness can be easily formed on the outer periphery of the base 4 that is relatively thin and easily deformed. Thus, the head main body 37 can be easily positioned at a position where the thickness of the release layer 6 can be made constant by the elastic restoring force of the movement support portion 35 and the seal member 52.

  Since the viscometer 69 for measuring the viscosity of the paint 7 is provided inside the paint tank 67 for storing the paint 7, the thickness of the release layer 6 as a coating film can be managed to be constant.

  Next, a second embodiment of the present invention will be described with reference to FIGS. Note that the same parts as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  In the present embodiment, the volume changing unit 14 of the coating head 13 includes an elastic bag 55 and a regulator 56 as a pressure changing unit, as shown in FIGS. The elastic bag 55 is made of an elastic material such as rubber and is formed in a bag shape. The elastic bag 55 is formed in an annular shape, is positioned in the upper end portion of the head main body 37, and is disposed coaxially with the head main body 37. Pressurized gas as a pressurized fluid is supplied to the elastic bag 55 through a pressurized fluid supply source (not shown), an electromagnetic valve 57, and a regulator 56 in this order. The elastic bag 55 naturally expands when the pressurized gas is supplied, and further expands as the pressure of the pressurized gas increases.

  The regulator 56 changes the pressure of the pressurized gas supplied into the elastic bag 55 according to a command from the control device 18. The electromagnetic valve 57 opens to allow the pressurized gas to be supplied into the elastic bag 55 and to allow the pressurized gas to be discharged from the elastic bag 55. The electromagnetic valve 57 is opened and closed according to a command from the control device 18.

  The volume changing unit 14 opens the electromagnetic valve 57 and the regulator 56 increases the pressure of the pressurized gas so that the elastic bag 55 is inflated to accommodate the volume of the paint 7 in the head body 37 (head body 37 The amount of paint 7 that can be accommodated in the interior is reduced. The volume changing unit 14 opens the electromagnetic valve 57 and discharges the pressurized gas in the elastic bag 55, or the regulator 56 reduces the pressure of the pressurized gas to reduce the elastic bag 55, thereby reducing the head body. The volume (the amount of the paint 7 that can be accommodated in the head main body 37) that can accommodate the paint 7 in 37 is increased. As described above, the volume changing unit 14 can change the volume in which the paint 7 in the head body 37 can be accommodated by changing the pressure of the pressurized gas supplied to the elastic bag 55 by the regulator 56.

  In the present embodiment, as in the first embodiment described above, the head body 37 is gradually lowered to apply the coating 7 on the outer peripheral surface 4c in order from the upper end 4a to the lower end 4b of the base 4. Further, in the present embodiment, when the base body 4 is attached / detached, that is, during setup, the control device 18 opens the electromagnetic valve 57 to discharge the pressurized gas in the elastic bag 55 or regulator as shown in FIGS. 56, the pressure of the pressurized gas is lowered, the elastic bag 55 is reduced, and the elastic bag 55 is spaced from the liquid surface 7a of the paint 7 so that the liquid surface 7a of the paint 7 is more than the inner peripheral wall 47. Make it low. In the present embodiment, when applying the coating 7 to the outer peripheral surface 4c of the base body 4, the control device 18 opens the electromagnetic valve 57 and discharges the pressurized gas in the elastic bag 55 as shown in FIG. Alternatively, the pressure of the pressurized gas is gradually increased in the regulator 56 to inflate the elastic bag 55 so that the liquid level 7a of the paint 7 is maintained at a constant height higher than the inner peripheral wall 47.

  According to the present embodiment, the regulator 56 changes the pressure of the pressurized gas in the elastic bag 55 in accordance with a command from the control device 18, so that even a minute change in the liquid level 7 a of the paint 7 in the head body 37 can be achieved. Accordingly, the elastic bag 55 can be inflated, so that the liquid level 7a of the paint 7 in the head body 37 can be reliably kept constant. Therefore, the release layer 6 as a coating film having a uniform thickness can be more reliably formed.

  Further, since the bottom surface of the head body 37 becomes lower concentrically from the base body 4, the coating 7 is surely returned to the head body 37 when the liquid level 7 a of the coating 7 in the head body 37 is lowered after the coating is completed. Therefore, even if the base body 4 is removed from the inside of the head main body 37, the paint 7 does not overflow from the head main body 37, so that it is not necessary to seal the head main body 37 with a mask or the like, so that it can be applied without a mask. It becomes possible. Accordingly, since it is not necessary to clean the mask, it is possible to prevent an increase in the number of man-hours required for the setup work.

  In this embodiment, for example, a pressurized liquid may be used as a pressurized fluid other than the pressurized gas.

  Next, a third embodiment of the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the part same as 1st and 2nd embodiment mentioned above, and description is abbreviate | omitted.

  In the present embodiment, the volume changing unit 14 of the coating head 13 includes a magnet 58, an electromagnet 59, and a magnetic force controller 60 as a voltage changing unit, as shown in FIGS. The magnet 58 is a so-called permanent magnet and is formed in an annular shape. The outer diameter of the magnet 58 is smaller than the inner diameter of the lid body 49 of the lid body 44. The inner diameter of the magnet 58 is formed larger than the outer diameter of the base body 4. The magnet 58 is disposed coaxially with the base body 4 and the head main body 37, and is provided so as to be movable along the axis P with respect to the lid main body 49, that is, the head main body 37. The magnet 58 is supported by the linear guide 61 so as to be able to enter the head main body 37 through the inner edge of the lid main body 49 and to move away from the head main body 37.

  The linear guide 61 includes a rail erected from the support base 34 in a state where the longitudinal direction is parallel to the vertical direction, and a slider that is movable with respect to the rail along the longitudinal direction of the rail, that is, the vertical direction. The aforementioned magnet 58 is attached to the slider. The linear guide 61 causes the magnet 58 to enter the head main body 37 and move in a direction away from the head main body 37.

  The electromagnet 59 is attached to the bottom plate portion 45 of the head body 37 and is disposed at a position facing the magnet 58 along the axis P. When a voltage is applied from a power source (not shown), the electromagnet 59 generates a magnetic force having a polarity (reverse polarity) different from the polarity of the magnet 58 on the side facing the bottom plate 45 of the head body 37 on the side facing the magnet 58. appear. That is, the magnet 58 and the electromagnet 59 repel each other. The repulsive force, that is, the force that lifts the magnet 58 is changed depending on the magnitude of the voltage applied to the electromagnet 59. The magnetic force controller 60 changes the voltage applied to the electromagnet 59 in accordance with a command from the control device 18.

  When the voltage applied by the magnetic force controller 60 to the electromagnet 59 is zero or small in accordance with a command from the control device 18, the volume changing unit 14 weakens the above-described repulsive force, and the magnet 58 is lowered. By increasing the amount of penetration into the head main body 37 (the mass of the part that has entered), the volume that can accommodate the paint 7 in the head main body 37 (the amount of the paint 7 that can be accommodated in the head main body 37) is reduced. In addition, when the voltage applied by the magnetic force controller 60 to the electromagnet 59 is increased according to a command from the control device 18, the volume changing unit 14 increases the repulsive force described above, and the magnet 58 is lifted. By reducing or eliminating the amount of penetration into the head main body 37 (the mass of the part that has entered), the volume capable of accommodating the paint 7 in the head main body 37 (the amount of the paint 7 that can be accommodated in the head main body 37) is increased. . Thus, the volume changing unit 14 can change the volume in which the paint 7 in the head body 37 can be accommodated by raising or lowering the magnet 58 by increasing or decreasing the magnetic force of the electromagnet 59.

  In the present embodiment, as in the first and second embodiments described above, the head body 37 is gradually lowered to apply the coating 7 on the outer peripheral surface 4c in order from the upper end 4a to the lower end 4b of the base 4. To do. Further, in the present embodiment, when the base body 4 is attached / detached, that is, during setup, the control device 18 raises the magnet 58 by increasing the magnetic force generated by the electromagnet 59 in the magnetic force controller 60 as shown in FIGS. Then, the magnet 58 is spaced from the liquid level 7 a of the paint 7, and the liquid level 7 a of the paint 7 is made lower than the inner peripheral wall 47. In the present embodiment, when the coating material 7 is applied to the outer peripheral surface 4c of the base body 4, the controller 18 causes the magnetism controller 60 to weaken the magnetic force generated by the electromagnet 59 as shown in FIG. Is gradually lowered to keep the liquid level 7a of the paint 7 at a constant height higher than the inner peripheral wall 47.

  According to the present embodiment, the magnetic force generated by the electromagnet 59 is changed according to a command from the control device 18 to change the amount of penetration of the magnet 58 into the head main body 37. The magnet 58 can be taken in and out of the head main body 37 by following a minute change in the liquid level 7a. For this reason, the liquid level 7a of the paint 7 in the head main body 37 can be reliably kept constant. Therefore, the release layer 6 as a coating film having a uniform thickness can be more reliably formed.

  Further, since the bottom surface of the head body 37 becomes lower concentrically from the base body 4, the coating 7 is surely returned to the head body 37 when the liquid level 7 a of the coating 7 in the head body 37 is lowered after the coating is completed. Therefore, even if the base body 4 is removed from the inside of the head main body 37, the paint 7 does not overflow from the head main body 37, so that it is not necessary to seal the head main body 37 with a mask or the like, so that it can be applied without a mask. It becomes possible. Accordingly, since it is not necessary to clean the mask, it is possible to prevent an increase in the number of man-hours required for the setup work.

  In the embodiment described above, the viscometer 69 is disposed in the paint tank 67. However, in the present invention, the viscometer 69 may be disposed in the supply pipe 70. Furthermore, in the embodiment described above, the release layer 6 is formed, but the coating film forming apparatus 1 of the present invention may form the primer layer 3.

  In the embodiment described above, the case where the release layer 6 of the fixing belt 2 is formed is shown. However, the present invention is not limited to the fixing belt 2, and a coating film is formed on various endless belts and cylindrical articles. Of course, it may be. In the above-described embodiment, an example of the endless belt-shaped fixing belt 2 has been shown, but the present invention naturally includes an outer peripheral surface of a roller core as a cylindrical object to be coated made of metal or the like. You may apply to the fixing roller obtained by apply | coating the coating material 7 and forming a coating film.

  In the above-described embodiment, the base 4 is fixed and the support base 34 of the coating head 13 is moved. However, in the present invention, the support base 34 of the coating head 13 may be fixed and the substrate 4 may be moved, or both the support base 34 and the substrate 4 of the coating head 13 may be moved.

  The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the scope of the present invention. That is, the holding unit 11, the moving unit 12, the moving support unit 35, and the like are not limited to the configurations and arrangements described in the embodiments, and may have various configurations and arrangements.

(A) is a front view which shows the schematic structure of the coating-film formation apparatus concerning the 1st Embodiment of this invention, (b) is the outline of the coating-film formation apparatus shown by Fig.1 (a). It is a side view which shows the structure of. It is explanatory drawing which shows the state by which the head main body of the application | coating head of the coating-film formation apparatus shown by Fig.1 (a) was located in the application | coating start position. It is explanatory drawing which shows the state which has apply | coated the coating material to the outer peripheral surface of a base | substrate while the head main body of the application | coating head shown by FIG. 2 descend | falls gradually. It is explanatory drawing which shows the state by which the head main body of the application | coating head shown by FIG. 3 was located in the application completion position. It is explanatory drawing which shows the state by which the head main body of the application | coating head of the coating-film formation apparatus concerning the 2nd Embodiment of this invention was located in the application | coating start position. It is explanatory drawing which shows the state which has apply | coated the coating material to the outer peripheral surface of a base | substrate while the head main body of the application | coating head shown by FIG. 5 descend | falls gradually. It is explanatory drawing which shows the state by which the head main body of the application | coating head shown by FIG. 6 was located in the application completion position. It is explanatory drawing which shows the state by which the head main body of the coating head of the coating-film formation apparatus concerning the 3rd Embodiment of this invention was located in the application | coating start position. It is explanatory drawing which shows the state which has apply | coated the coating material to the outer peripheral surface of a base | substrate while the head main body of the application | coating head shown by FIG. 8 descend | falls gradually. It is explanatory drawing which shows the state by which the head main body of the application | coating head shown by FIG. 9 was located in the application completion position. It is a perspective view of a fixing belt obtained by forming a coating film by the coating film forming apparatus of the present invention. It is sectional drawing which follows the XII-XII line | wire in FIG.

Explanation of symbols

1 Coating film forming device 4 Substrate (object to be coated)
4c Outer peripheral surface 6 Release layer (coating film)
7 Paint 7a Liquid level 11 Holding part 12 Moving part 13 Application head 14 Volume changing part (volume changing means)
18 Control device (control unit)
37 Head body 40 Intruder 41 Linear actuator (Intruder moving part)
48 Inclined surface 53 Liquid level detection sensor (measuring means)
55 Elastic bag 56 Regulator (pressure change part)
58 magnets 59 electromagnets 60 magnetic force controller (voltage changing unit)
71 Passage (refrigerant circulation part)
72 Cooling water circulation device (heat exchanger)
P shaft core

Claims (8)

In an application head that moves relative to the object to be coated along the axis of the object to be coated, applies a paint to the outer peripheral surface of the cylindrical surface of the object to be coated, and forms a coating film.
It is formed in an annular box shape and contains the paint, and an opening is provided over the entire circumference on the inner peripheral surface, and the paint is passed through the inside of the object to be coated. A head body to be applied to the outer peripheral surface;
Measuring means for measuring the height of the liquid level of the paint in the head body;
A volume changing means capable of changing a volume capable of accommodating the paint in the head body;
Based on the height of the liquid level measured by the measuring means, the control unit for controlling the volume changing means and appropriately changing the height of the liquid level of the paint in the head body,
An application head comprising:   The control unit is a control unit that controls the volume changing unit so that the height of the liquid level measured by the measuring unit during application of the paint is constant. Application head. The volume changing means is
An intruder provided so as to be movable with respect to the head main body in a direction of entering the head main body or moving away from the head main body;
2. An intruder moving section that moves the intruder into the head main body or moves in a direction away from the head main body according to a command from the control section. Item 3. The coating head according to Item 2.   The coating film forming apparatus according to claim 3, further comprising: a refrigerant circulation unit that circulates the refrigerant provided in the intruder; and a heat exchanger that maintains a constant temperature of the refrigerant in the refrigerant circulation unit. . The volume changing means is
An elastic bag made of an elastic material which is positioned in the head body and expands when supplied with pressurized fluid;
A pressure changing unit that changes the pressure of the pressurized fluid supplied into the elastic bag according to a command from the control unit;
The coating head according to claim 1, wherein the coating head is provided. The volume changing means is
A magnet provided so as to be movable with respect to the head main body in a direction to enter the head main body or to leave the head main body;
An electromagnet attached to the head body relative to the magnet and generating a magnetic force having a polarity different from that of the magnet when a voltage is applied;
A voltage changing unit for changing a voltage applied to the electromagnet according to a command from the control unit;
The coating head according to claim 1, wherein the coating head is provided.   The bottom surface of the head main body is provided with an inclined surface that gradually faces upward toward the center of the head main body and is inclined with respect to the axis. The coating head according to any one of 6. In a coating film forming apparatus that forms a coating film by applying a paint to the cylindrical outer peripheral surface of the object to be coated,
A holding unit that exposes the outer peripheral surface and holds the object to be coated in a state in which the axis of the object is parallel to the vertical direction;
An application head that contains the paint and moves relative to the object to be coated and applies the paint to the outer peripheral surface of the object;
A moving unit that relatively moves the holding unit and the coating head along the axis; and
A coating film forming apparatus comprising the coating head according to any one of claims 1 to 7 as the coating head.

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