JP2008155124A - Apparatus and method for coating side surface of piston ring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To coat the side surfaces of the piston ring through an automatic operation with excellent productivity. <P>SOLUTION: An apparatus for coating the side surfaces of the piston ring has mounts 3 attached in a rotatable way to individual supports 7a of the turntable 7 and supporting the piston ring 1, a heating unit 11 heating side surfaces 1a and 1b of the piston ring 1, a coating unit 12 coating the heated and rotating side surfaces 1a and 1b of the piston ring 1 with a coating 5 and a turnover unit 13 making upside down the side surfaces 1a and 1b of the piston ring 1 by reversing the mounts 3 vertically and mounting the mounts 3, together with the piston ring 1, again on the supports 7a of the turntable 7. The side surfaces 1a and 1b are continuously and automatically heated and coated with a coating while the piston ring 1 is turned over with the turnover unit 13. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a coating apparatus and a coating method for coating a side surface of a piston ring with a heat resistant resin to form a heat resistant film.

  In an internal combustion engine in which the piston reciprocating movement is repeated by the explosion of fuel in the combustion chamber, the piston ring repeatedly collides with the inner surface of the ring groove of the piston in which the piston ring is mounted as the piston reciprocates. Further, during operation of the internal combustion engine, the side surface of the piston ring rotating in the circumferential direction slides on the inner surface of the ring groove. Due to the explosion of the fuel, the top ring and ring groove of the gasoline engine are heated to a temperature close to 250 ° C., and further heated to a higher temperature in the diesel engine. In a piston made of aluminum alloy, when the piston ring collides with the surface of the ring groove at a high temperature, a part of the surface of the piston undergoes fatigue failure, causing surface peeling and peeling off a small piece of aluminum alloy. The metal pieces to be peeled fall off between the piston ring and the ring groove, and the new surface of the aluminum alloy that appears by being hit or rubbed or by peeling of the metal pieces is further subjected to collision and friction by the side surface of the piston ring. In response, a phenomenon occurs in which the aluminum alloy is transferred to the side surface of the piston ring (migration). This is called “aluminum adhesion”. As aluminum adhesion progresses, the piston ring itself adheres to the ring groove, impairing the airtight performance of the piston ring, and a so-called “blow-by” phenomenon occurs in which high-pressure combustion gas flows out from the combustion chamber to the crank chamber. The engine output is reduced. In addition, the blow-by gas causes adverse effects of oil combustion and sludge generation, restricting the original movement of the oil ring and reducing or losing the hermetic function of the oil ring, resulting in an increase in oil consumption. Even if the piston ring is not fixed, the air-tightness between the side surface of the piston ring and the ring groove surface is still impaired due to the bulge of the side surface of the piston ring or the rough surface of the ring groove due to aluminum adhesion, which increases blow-by. Invite you.

  In order to prevent aluminum adhesion, a number of methods for preventing direct contact between the piston material of the aluminum alloy and the piston ring have been proposed. For example, Patent Document 1 below discloses a method of forming an oxide film by subjecting the surface of a ring groove to an anodic oxidation treatment (alumite treatment), and further filling a lubricating substance in the micropores of the oxide film. The hard oxide film mainly composed of aluminum oxide formed on the surface of the ring groove by the alumite treatment prevents the aluminum powder from falling off and prevents the piston ring from adhering. However, the technique of anodizing the ring groove requires large-scale equipment and high manufacturing costs, and a processing groove is generated in the ring groove formed at the time of manufacturing the ring groove. Since the alumite film is formed, the alumite surface is rough, the air tightness of the contact surface of the piston ring is lowered, and the initial blow-by amount is increased.

  Thus, Patent Documents 2 and 3 below show piston rings that form a film. In Patent Document 2, a tetrafluoroethylene in which a phosphate film or a triiron tetroxide film is formed on the side surface of a piston ring and a solid lubricant such as molybdenum disulfide, graphite, carbon, boron nitride is dispersed thereon A heat-resistant / abrasion-resistant resin film such as a resin or oxybenzoyl polyester resin is formed. In Patent Document 3, a film in which a solid lubricant such as molybdenum disulfide is dispersed in a heat-resistant resin such as epoxy resin, phenol resin, polyamide, or polyimide is formed on the side surface of the piston ring. The film formed on the piston ring has an effect of preventing the aluminum adhesion generated between the ring groove and the side surface of the piston ring by the solid lubricant itself cleaving. The resin film is simple and easy to apply a paint prepared by mixing a solid lubricant in a solution of resin film components dissolved in a solvent to the side of the piston ring, then evaporate and dry the solvent, and fire the film Because it can be formed by a simple method, it is used exclusively as a countermeasure against piston ring aluminum adhesion.

  However, when the annular paint surface of the piston ring is placed horizontally and the spray gun is moved horizontally to paint, the conventional paint method incurs high costs due to material yield or productivity reduction. Proposals have been made for further improvements to the piston ring painting method or painting equipment to improve the method.

  In Patent Document 4 below, a plurality of piston rings are fixed to the outer periphery of a cylindrical coating jig at equal intervals in the axial direction, the piston ring is preheated together with the coating jig, and then the jig is centered in the coating process. In order to solve the above-mentioned problems, a new painting method, a painting device and a painting jig for a piston ring for painting simultaneously on both sides of a piston ring by a pair of painting guns that are rotated in parallel to the rotation axis are disclosed. is there. In this coating method, a paint absorbing sheet is interposed on the outer periphery of the cylindrical jig to prevent the paint from adhering to the outer peripheral surface of the cylindrical jig, so that the cylindrical jig can be used repeatedly and the sheet absorbs the paint. Therefore, there is an advantage that it is possible to prevent adhesion of paint burrs to the inner peripheral portion of the piston ring. In addition, this painting method has an advantage that both side surfaces of the piston ring can be painted at the same time, but there is a problem that a lot of man-hours are required for packing the jig for arranging the piston ring on the alignment jig. Also, since the piston ring in a free state does not form a perfect circle, even if a paper sheet for absorbing paint is interposed between the alignment jig and the piston ring, the surface of the sheet and the inner peripheral surface of the piston ring Since gaps are always formed between them, the occurrence of paint burrs cannot be prevented. In addition, after preheating, since the application of paint starts from one direction of the cylindrical jig, there is a temperature difference in the piston ring where the paint is applied between the start and end of painting, and the temperature of the piston ring changes at the end of painting. If it is low, the paint may flow in the outer circumferential direction due to the rotation of the piston ring, and the film thickness of the coating film may become uneven. Conversely, if the temperature of the piston ring is too high at the start of coating, the adhesion of the coating film may be impaired. Since the paint is sprayed from the outer peripheral sliding surface side of the piston ring formed with an angle, the paint tends to be applied more unevenly than the conventional method.

  Patent Document 5 below discloses a piston ring that forms an organic resin film containing a solid lubricant using an electrostatic coating machine. In the electrostatic coating method disclosed in Patent Document 5, it is considered that paint is less wasteful and the film thickness is more uniform than in the past. However, the paint that can be electrostatically coated does not necessarily exhibit the performance of preventing the aluminum adhesion of the piston ring, and the piston ring is also applied to the outer peripheral sliding surface or inner peripheral sliding surface of the piston ring that does not require a coating film. There is also a difficulty in being painted with the same thickness as the side face.

  Patent Documents 6 and 7 listed below are a rotatable turntable, a plurality of work turntables that are rotatably provided on the turntable, and a spray mechanism that sprays paint onto the work, Disclosed is a coating apparatus including a spraying mechanism provided on the outside of a turntable and preheating and postheating heating units provided before and after the rotation direction of the spraying mechanism. When the piston ring is painted by this coating device, the piston ring is preheated by the high-frequency induction heating device in the previous stage, and then the turntable is rotated and coating is performed on the stage having the paint spraying mechanism. Since the coating devices of Patent Documents 6 and 7 preheat each piston ring separately immediately before painting, there is a problem that a temperature difference occurs between the piston ring to be painted first and the piston ring to be painted last, as in Patent Document 4. It is considered that the coating film can be applied at a constant rotation speed within the range where the paint gun can spray the paint, and thus the adhesion failure of the coating film and the uneven coating thickness can be suppressed.

JP-A 63-170546 Japanese Utility Model Publication No. 60-82552 JP-A-62-233458 Japanese Patent Laid-Open No. 7-119834 JP-A-9-317887 Japanese Patent Laid-Open No. 10-328603 Japanese Patent Laid-Open No. 11-253849

  However, since the coating apparatus disclosed in Patent Documents 6 and 7 uses a turntable and requires a preheating mechanism in the stage before coating, a small diameter and thin heat capacity during rotation of the turntable or during painting. As the temperature of the small piston ring decreases, there is a high possibility of paint flow. In this case, if the preheating temperature of the piston ring is increased in order to prevent the temperature of the piston ring from lowering, there is a possibility that the hardness of the hard chrome plating film deposited on the outer peripheral surface of the piston ring may be reduced. If the substrate temperature of the object to be coated at the start of coating is too high, generally the adhesion of the coating film is lowered, so that the preheating temperature cannot be generally increased. In addition, when the temperature change of the piston ring due to the temperature is taken into consideration, there is a problem that the cost of the air conditioning equipment increases. Furthermore, in order to coat both side surfaces of the piston ring, it is necessary to use the coating apparatus twice, and there is a problem that productivity is lowered.

  An object of this invention is to provide the coating apparatus and the coating method which are excellent in productivity which coats the side surface of a piston ring by automatic operation.

  An object of this invention is to provide the coating apparatus and coating method which can form a coating film by the thickness controlled on the side surface of the piston ring.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a coating apparatus and a coating method that are excellent in film adhesion and yield, and that can coat the side surface of a piston ring with a uniform film thickness.

  The piston ring side surface coating apparatus of the present invention has a peripheral part (7b) provided with a plurality of support parts (7a), and is a turntable that is rotatably arranged on a horizontal plane around a vertical revolution axis (7c). (7) and a mounting base that is mounted on each support portion (7a) of the turntable (7) and supports the piston ring (1) so as to be rotatable on a horizontal plane around the vertical rotation axis (3a). (3) and a heating device (11) for heating the side surfaces (1a, 1b) of the piston ring (1) supported by the mounting base (3) that rotates around the rotation shaft (3a) The coating device (12) for applying the paint (5) to the side surfaces (1a, 1b) of the piston ring (1), and the mounting base (3) together with the piston ring (1) ) And turn the mounting base (3) upside down so that the sides (1a, 1b) of the piston ring (1) are turned upside down, and then the mounting base (3) is attached to the turntable (7) together with the piston ring (1). ) Support part ( A reversing device (13) to be mounted again on 7a). The piston ring (1) is rotated on a horizontal plane, one side (1a, 1b) of the piston ring (1) is heated by the heating device (11), and then one of the ones heated by the coating device (12) is heated. The paint (5) is applied to the side surfaces (1a, 1b), and the piston ring (1) is reversed by the reversing device (13), and the other side surface (1b, 1) of the piston ring (1) is heated by the heating device (11). 1a) is heated, and then the paint (5) is applied to the other side (1b, 1a) heated by the coating device (12), thereby heating and painting on both sides (1a, 1b). It can be done continuously and automatically. Therefore, the paint (5) is securely applied to the side surfaces (1a, 1b) of the piston ring (1) heated to the optimum temperature, and the paint film is firmly attached to improve the adhesion and improvement of the paint film. Yield is achieved. In addition, since coating material flow due to temperature drop of the piston ring (1) or variation in coating thickness due to nonuniform temperature can be suppressed, good coating quality can be obtained in terms of film thickness and appearance. Attach the piston ring (1) to the mounting base (3) so that it can rotate, and attach the mounting base (3) to the support part (7a) of the turntable (7) so that it can revolve and mount it on the turntable (7). By revolving the table (3), the piston ring (1) can be continuously heated, painted, and reversed. In addition, since the revolving shaft (7c) of the turntable (7) and the rotating shaft (3a) of the mounting base (3) can be arranged vertically, it is easy to attach, detach and invert the ring mounting jig. There is an advantage that the mounting base (3) with (1) attached at another place can be attached to the rotating shaft (3a) of the turntable (7).

  In this specification, the “heating device” is a device that raises the temperature by directly or indirectly heating the side surface of the piston ring in contact or non-contact regardless of the principle, action, or structure. Yes, including all the heating means that can be used, such as a heating coil of a high-frequency induction heating device, a lamp of an infrared heating device. The “coating device” is a device that applies a paint to the side surface of the piston ring, and includes all usable painting means such as a spray device and a brush.

  The piston ring side surface painting method of the present invention has a step of mounting the piston ring (1) on the mounting base (3) by the ring mounting device (10), a vertical revolving shaft (7c), and is disposed horizontally. The step of horizontally mounting the mounting base (3) on each of the plurality of support portions (7a) provided on the turntable (7), and the turntable (7) together with the mounting base (3) around the revolution shaft (7c) And the mounting base (3) together with the piston ring (1) around the vertical rotation axis (3a) on the horizontal plane. While rotating, the step of heating one side surface (1a, 1b) of the piston ring (1) supported by the mounting base (3) by the heating device (11) and the rotating piston ring (1) were heated. Applying paint (5) to one side (1a, 1b), revolving the turntable (7) on a horizontal surface, and reversing device (13) together with piston ring (1) and mounting base (3) With the step of stopping the rotation of the mounting base (3) and the reversing device (13), the mounting base (3) together with the piston ring (1) is taken out from the support part (7a) of the turntable (7), After reversing the side of the piston ring (1) (1a, 1b) by reversing the mounting base (3), the mounting base (3) together with the piston ring (1) is attached to the support section of the turntable (7). A step of re-attaching to (7a), a step of revolving the turntable (7) on a horizontal plane around the revolution axis (7c), and bringing the inverted mounting base (3) closer to the heating device (11) The piston ring (1) supported by the mounting base (3) by the heating device (11) while rotating the mounting base (3) on the horizontal plane together with the piston ring (1) around the vertical rotational axis (3a) Heating the other side surface (1b, 1a), applying the paint (5) to the heated other side surface (1b, 1a) of the rotating piston ring (1), and a turntable ( 7) revolves on the horizontal plane to bring the mounting base (3) closer to the ring removal device (14) and stop the rotation of the mounting base (3), and the ring removal device (14) And 3) removing the piston ring (1). In the piston ring side surface painting method of the present invention, the process from attaching the piston ring (1) to the mounting base (3) to the process of removing the piston ring (1) from the mounting base (3) by the ring removing device (14). It can be done continuously and automatically.

In the coating apparatus and the coating method of the present invention, the following actions and effects can be obtained.
<1> Since the side surface of the rotating piston ring can be heated for coating, a coating film having strong adhesion, uniform film thickness, and initial coating quality can be formed on the side surface.
<2> Even when painting a paint with a low evaporation start temperature, while rotating the piston ring at a high speed, the side surface of the piston ring with a small heat capacity is continuously heated and the temperature drop is suppressed, while the outer periphery slides on the side surface. A paint film having a uniform thickness can be formed in the circumferential direction of the side surface while preventing the paint from flowing to the moving surface.
<3> Since the temperature drop on the side surface of the piston ring can be suppressed, the coating film can be thickened by a single treatment.
<4> The side surface of the piston ring can be painted continuously and automatically.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode of a piston ring side surface coating apparatus and a coating method according to the present invention will be specifically described with reference to FIGS.

  As shown in FIG. 3, the piston ring (1) formed by the piston ring side surface painting apparatus and the piston ring side surface painting method of the present invention includes, for example, a pair of side surfaces (1a, 1b) composed of an upper surface and a lower surface, It has an inner peripheral surface (1d) that faces the inner surface of a ring groove formed in a piston (not shown) and an outer peripheral surface (1c) that forms a barrel surface that is in sliding contact with the inner wall of a cylinder (not shown). Polyamideimide resin films (2a, 2b) are respectively formed on the side surfaces (1a, 1b) by applying a resin material.

  The embodiment of the piston ring side surface painting apparatus of the present invention shown in FIGS. 1 and 2 includes a turntable (index turntable) (7) having an outer peripheral portion (7b) provided with a plurality of support portions (7a), A mounting base (3) that is independently rotatably mounted on each of the plurality of support portions (7a) provided on the turntable (7) and supports the piston ring (1), and a mounting base (3) A heating device (11) for heating the main surfaces (1a, 1b) of the supported and rotating piston ring (1) and a coating device (12) for applying the paint (5) to the heated main surfaces (1a, 1b) ) And the piston ring (1) and the mounting base (3) are removed from the support (7a) of the turntable (7), and the side of the piston ring (1) is reversed by turning the mounting base (3) (1a, 1b ) And the reversing device (13) for attaching the mounting base (3) to the support portion (7a) of the turntable (7) together with the piston ring (1).

  As shown in the plan view of FIG. 1, the turntable (7) includes a revolving shaft (7c) arranged vertically, eight arms (7d) extending radially outward from the revolving shaft (7c), A support portion (7a) provided on the outer peripheral portion (7b) of each arm (7d). Since the turntable (7) is rotatably supported on a horizontal plane around a revolving shaft (7c) arranged vertically by a bearing device (not shown), it can be called a horizontal piston ring side coating device. The revolution shaft (7c) is rotated at an accurate rotation angle and rotation speed by a mechanical operation motor such as a servo motor, a stepping motor, or an electric motor or a pneumatic motor via a power transmission device such as a pressure roller (not shown). The If necessary, a rotary encoder may be provided in the motor to detect and control the rotational angle position and rotational speed of the revolution shaft (7c). The arm (7d) of the turntable (7) extends radially outward from the revolution axis (7c) at a constant angular interval. The turntable (7) is rotated counterclockwise on a horizontal plane by a revolving motor (not shown) connected to the revolving shaft (7c).

  As shown in FIG. 2, the mounting base (3) mounted on the support portion (7a) so as to be rotatable on a horizontal plane alone is rotatable and vertically supported by the support portion (7a). 3a), a header (3b) provided at one end of the rotating shaft (3a), an inner peripheral surface of the piston ring (1) that extends radially outward from the header (3b) and is attached to the header (3b) ( 1d) is provided with three spokes (3c) that can be detachably mounted. The rotation shaft (3a) is rotated at an accurate rotation angle and rotation speed by an unillustrated electric motor such as a servo motor or a stepping motor or a mechanical operation motor such as a pneumatic motor attached to the support portion (7a). If necessary, a rotary encoder may be provided in the motor to detect and control the rotational angle position and rotational speed of the rotating shaft (3a). For example, a rotation motor (7e) that applies a rotational force to the support portion (7a) via a pressing roller such as a rubber roller may be provided. The mounting base (3) is attached to the turntable (7), but the rotation shaft (3a) is rotatably held by a bearing (not shown), and the rotation shaft (3a) is supported by each support portion of the turntable (7). The rubber roller that is detachably attached to (7a) and is attached to the rotation shaft (3a) contacts the rubber roller attached to the rotation motor (7e) so as to be rotatable.

  After the piston ring (1) is mounted concentrically on the outer end of the spoke (3d) of the mounting base (3), the mounting base (3) and the piston ring (1) are rotated at high speed. Although not shown, when the piston ring (1) is mounted on the mounting base (3), the piston ring (1) is expanded radially outward against the elasticity of the piston ring (1), and the piston ring (1) The inner peripheral surface (1d) is in contact with the V-shaped outer end of each spoke (3c), and the piston ring (1) is supported on the mounting base (3) by the elasticity of the piston ring (1) itself. can do. Two to four spokes (3c) are required, but an inner peripheral surface (1d) of a piston ring (1) that is provided with a notch (referred to as “mating portion”) and forms a cam shape in a free state. In order to arrange the center of the spoke (3c) as much as possible at the center, three spokes (3c) provided at an angular interval of about 120 degrees are preferable. Moreover, it is desirable to attach the piston ring (1) to the mounting base (3) by disposing an abutment portion in the middle of an angle of 120 degrees formed by adjacent spokes (3c).

  As shown in FIG. 1, the turntable (7) includes a mounting stage (20) having a ring mounting device (10) for detachably mounting a piston ring (1) on a mounting base (3), and a piston ring ( A first and second heating device (11) for heating the side surfaces (1a, 1b) of 1) and a coating device (12) for applying paint (5) to the side surfaces (1a, 1b) of the piston ring (1). 2 and the piston ring (1) and the mounting base (3) are removed from the support (7a) of the turntable (7), and the first and second heat coating stages (21, 22) are removed. 22), the side of the piston ring (1) (1a, 1b) is turned upside down by reversing the mounting base (3), and then the mounting base (3) together with the piston ring (1) again. A reversing stage (23) having a reversing device (13) for mounting the turntable (7) on the support (7a), and a ring removing device (14) for removing the painted piston ring (1) from the mounting base (3). ) There are six working stages including a removal stage (24) and a cleaning stage (25) provided with a cleaning device (15) for cleaning the mounting base (3) from which the piston ring (1) has been removed. The `` working stage '' equipped with the corresponding devices is the area where the piston ring (1) is mounted, the piston ring (1) is heated and the paint (5) is applied, and the piston ring (1) is reversed and removed. In each work stage, the corresponding processing is performed on the piston ring (1), so the rotation of the turntable (7) is stopped or decelerated as necessary, and each stage is accurately set after the set time has elapsed. The turntable (7) is controlled so as to sequentially cycle (20 to 25).

  As shown in FIG. 2, each of the first and second heating and painting stages (21, 22) is provided with a heating device (11) and a coating device (12), and the front stage of the mounting stage (20). A ring supply device (9) for carrying the unpainted piston ring (1) into the mounting stage (20) is provided. The ring supply device (9) drives the transfer conveyor (9a) to transfer the unpainted piston ring (1) to the ring mounting device (10) provided on the mounting stage (20). The ring mounting device (10) detachably mounts the piston ring (1) supplied from the ring supply device (9) on the mounting base (3) and drives the piston ring (1) by driving the conveyor (10a). ) Is mounted on the turntable (7) so that it can rotate independently on a horizontal surface.

  The removal stage (24) provided after the second heat painting stage (22) with the second spray (12b) removes the painted piston ring (1) from the mounting base (3) and conveys the conveyor. A ring removing device (14) for carrying out the painted piston ring (1) to the outside by driving of (14a) is provided. The cleaning stage (25) provided after the removal stage (24) has a cleaning device (15) for cleaning the mounting base (3) from which the piston ring (1) has been removed by the removal stage (24). Provided. Although not shown, the mounting base (3) to be cleaned in the cleaning stage (25) is removed from the support portion (7a) of the turntable (7) and carried into the mounting stage (20), and the ring mounting device (10) Will be fitted again.

  In the embodiment shown in FIG. 2, the first and second heat painting stages (21, 22) constituted by the same apparatus are shown. Each of the first and second heat painting stages (21, 22) is disposed above the piston ring (1) and measures the temperature of one side surface (1a, 1b) of the piston ring (1). (8), the heating device (11) for heating one side surface (1a, 1b) of the piston ring (1), and the one side surface (1a, 1b) of the piston ring (1) are heated to a predetermined temperature. And a coating device (12) for applying the paint (5) to the side surfaces (1a, 1b). The temperature sensor (8) is a radiation thermometer sensor that detects the temperature of the piston ring (1). The heating device (11) includes, for example, heating plates (11a, 11b) as first and second heating devices of a high-frequency induction heating device disposed adjacently above the piston ring (1). The coating device (12) is supplied with a container (4) filled with a liquid paint (5), a paint (5) stored in the container (4) and high-pressure air, and a paint ( The spray device includes sprays (12a, 12b) that spray 5) onto the side surfaces (1a, 1b) of the piston ring (1). The first spray coating stage (21) is provided with a first spray (12a), and the second spray coating stage (22) is provided with a second spray (12b). The first spray 12a and the second spray 12b basically have the same configuration. Thus, the temperature sensor (8), the heating device (11), and the coating device (12) having the same configuration are provided in the first and second heating and painting stages (21, 22).

  The piston ring (1) is mounted on the mounting base (3) in the support part (7a) so that it rotates clockwise, i.e., rotates, and the piston ring (1) rotates with the mounting base (3) while heating the heating device. (11) heats one side surface (1a, 1b) of the piston ring (1) and measures its temperature with the temperature sensor (8) .The temperature sensor (8) When it is detected that the paint has been heated, the paint (5) is sprayed from the first spray (12a) of the coating device (12) onto one side (1a, 1b) of the piston ring (1). Done. Without using the temperature sensor (8), the coating device (12) may apply the paint (5) when a certain time has elapsed after the heating of the side surface (1a) by the heating device (11).

  The heating device (11) and the coating device (12) are controlled by a control device (not shown) according to heating conditions separately obtained by experiments. If the frequency is selected, only the pole surface of the side surface (1a, 1b) of the piston ring (1) can be partially heated by the heating device (11) that performs high-frequency induction heating. Even on the side surface (1a, 1b) of the piston ring (1) on which the film is formed, the hardness of the chrome plating does not deteriorate, application can be started at a higher base temperature, and the degree of freedom in selecting the paint (5) is widened. As long as the side surface (1a, 1b) of the piston ring (1) can be heated to a predetermined temperature, the heating device (11) may be any means, but the side surface of the piston ring (1) during application and improvement of productivity In order to suppress the temperature drop of the piston ring (1), the sides (1a, 1b) of the piston ring (1) are continuously heated. It is desirable to heat the side surfaces (1a, 1b) of the ring (1), and in the case of heating with an infrared heater or a halogen lamp, a condensing lamp is preferable in order to increase the temperature rise rate of the piston ring (1). When the base material of the piston ring (1) is formed of a metal material, high-frequency induction heating that is easy to control is preferable. After the piston ring (1) is painted in advance, it is necessary to generate a heating output from the heating device (11) that does not cause “paint flow” when the piston ring is cooled. In the present invention, even when a paint having a low evaporation start temperature is applied, while the piston ring (1) having a small heat capacity is continuously heated and the piston ring (1) is rotated at a high speed, the temperature of the piston ring (1) is It is possible to suppress the decrease, prevent the paint from flowing to the outer peripheral surface (1c) of the piston ring (1), and form a coating film having a uniform thickness in the circumferential direction of the piston ring. Moreover, since the temperature drop of the piston ring (1) can be suppressed, the coating film can be thickened by one treatment. In this case, it is desirable that the temperature of the piston ring (1) at the end of painting is raised to a temperature higher than the temperature of the piston ring (1) at the start of painting. The adhesion of the coating film is determined by the base temperature of the piston ring (1) at the start of coating, and the hardness of the coating film is determined by the ultimate temperature. It is desirable to make the handling easy by setting the output of the heating device (11) so that the temperature rises to a temperature at which the resin film is cured below the firing temperature. When an abrasion-resistant film such as hard chrome plating is formed on the outer peripheral surface, the film is heated to a temperature that does not affect the hardness of the abrasion-resistant film. In the present embodiment, from the viewpoint of productivity, it is preferable to set the heating rate at which the side surfaces (1a, 1b) of the piston ring (1) are heated to 40-60 ° C. in 0.2-3 seconds. However, since the temperature increase rate of the piston ring (1) varies depending on the size of the piston ring (1) or the temperature at the start of heating, the output is obtained in advance by a heating device (11) suitable for each piston ring (1). There is a need.

  The coating device (12) has a nozzle device (6) that sprays downward toward one side surface (1a, 1b) of the piston ring (1). Immediately after heating the side surface (1a, 1b) of the piston ring (1) by the heating device (11), the coating device (on the side surface (1a, 1b) of the piston ring (1) having a surface temperature within an optimal fixed range ( Since the coating according to 12) can be started and finished, a coating film having strong adhesion, uniform film thickness and initial coating film quality can be formed. Similar to the heating conditions, the coating device (12) is controlled by a control device (not shown) in accordance with the spray conditions and the spray start timing obtained in advance by experiments. If paint is sprayed from the coating device (12) based on the detection signal of the temperature sensor (8) that detects the radiation temperature from each side (1a, 1b) of the piston ring (1), the film adhesion and appearance And non-uniform film thickness can be reduced.

  When a spray that mixes high-pressure air with the paint (5) supplied from the paint tank (4) and jets the mist-like paint (5) from the nozzle device (6) is used in the painting device (12), the piston ring ( While rotating the piston ring (1) about the center of 1) as a rotation axis, either side surface (1a) of the piston ring (1) from the opposite position of the side surface (1a, 1b) of the rotating piston ring (1) , 1b) can be sprayed with paint (5). Therefore, the ratio of spraying to useless surfaces or spaces other than the side surfaces (1a, 1b) of the piston ring (1) is reduced, and the waste of the paint (5) can be reduced. Also, paint (5) is applied to the side surfaces (1a, 1b) of the piston ring (1) from above in a substantially vertical direction to suppress the coating amount on the outer peripheral surface (1c) and inner peripheral surface (1d). Can do.

  In the piston ring side surface coating device shown in FIG. 1, a pair of heating devices (11) and a coating device (12) are provided on both sides of the reversing device (13). ) Is provided with a first spray (12a) for applying the paint (5) to one side surface (1a) of the piston ring (1), and the other coating device (12) is provided with a paint (5 ) Is attached to the second spray (12b). The side surface (1a, 1b) of the piston ring (1) was heated to a predetermined temperature when a predetermined preheating time by the heating device (11) elapses or the temperature was measured by the temperature sensor (8). At that time, the application of the paint (5) by the first and second sprays (12a, 12b) is started. In this embodiment, since the piston ring (1) rotates slightly eccentrically, the first and second sprays (12a, 12b) are optimal. However, if the device compensates for eccentricity, The paint (5) may be applied by, for example. When a coating film with poor adhesion is formed unless a base coating is provided, 2 is applied to each of the first and second sprays (12a, 12b) facing the side surfaces (1a, 1b) of the piston ring (1). If one spray nozzle is provided and one spray nozzle is used for forming the undercoat, the entire coating can be coated with good adhesion.

  The reversing device (13) provided between the first spray (12a) and the second spray (12b) of the coating device (12) grips the mounting base (3) that supports the piston ring (1). A robot arm that is removed from the support portion (7a) of the turntable (7) and turned over, and further mounts the mounting base (3) on the support portion (7a) of the turntable (7) together with the stone ring (1). Equipped with an articulated robot. The reversing device (13) grips only the piston ring (1) mounted on the mounting base (3) fixed to the rotating shaft (3a) and holds the mounting base (3) on the turntable (7). After removing the piston ring (1) from the mounting base (3) and turning it over, it may be mounted again on the mounting base (3). The reversing device (13) grips the mounting base (3) held by the support part (7a) of the turntable (7), removes it from the support part (7a), and together with the mounting base (3), the piston ring (1 ) And turn the support (7a) of the turntable (7) to place the mounting base (3) again, while holding the mounting base (3) on the turntable (7), the piston ring ( Any device that grips, removes and inverts only 1) is included in the inversion device (13).

  As the piston ring (1) used in the embodiment of the present invention, a metal-based material including cast iron, steel, stainless steel, titanium alloy, and aluminum alloy is often used, but it is used in the coating apparatus and the coating method of the present invention. The piston ring is not limited to them. However, in order to prevent paint flow when the piston ring (1) rotates, it is necessary to heat the side surface of the piston ring (1) to about 40 to 60 ° C. or higher.

  In order to increase the adhesion of the coating films (2a, 2b), a chemical conversion treatment film is preferably formed in advance on both side surfaces (1a, 1b) of the piston ring (1). For steel materials, phosphate treatment and oxalate treatment are effective. When stainless steel with a high chromium content is subjected to nitriding in advance, a chemical conversion film is easily formed. A black dyeing process can be used on the non-nitrided side surface. Anodization is desirable for piston rings made of titanium or aluminum alloy. However, even if the adhesion of the coating films (2a, 2b) is somewhat lowered, it is effective without providing a ground treatment unless it is a malfunction when using the piston ring.

Resin film formed after curing of the coating film (2a, 2b) are polyimide, polyamide-imide (PAI), polyimide, SiO ₂ hybrid resin of polyamide-imide, epoxy resin, polybenzimidazole resin or their mixtures comprising at least one Alternatively, it is possible to use a resin film conventionally used for preventing aluminum adhesion, including a resin in which at least one kind of particles such as solid lubricant, hard particles or carbon black conventionally used in composites is dispersed. Also in this case, it is necessary to conduct a coating experiment in advance and determine the application start temperature and the like.

  When painting both side surfaces (1a, 1b) of the piston ring (1) using the piston ring side surface painting device shown in FIG. 1 and FIG. 2, first the ring conveyor is driven by driving the conveyor (10a). (10) is moved in the direction of the arrow, and the unpainted piston ring (1) supplied from the outside of the apparatus is carried into the mounting stage (20). Subsequently, a mounting base (3) is rotatably attached to each of the plurality of support portions (7a) provided on the outer peripheral portion (7b) of the turntable (7), and a piston ring ( The inner peripheral surface (1d) of 1) is brought into contact with the V-shaped tips of the three spokes (3c), and the piston ring (1) is detachably mounted on the mounting base (3). The mounting work of the piston ring (1) to the mounting base (3) and the mounting work of the mounting base (3) to the support (7a) of the turntable (7) are all automatically performed by the ring mounting device (10). Done. When the mounting base (3) is mounted on the support section (7a) of the turntable (7), a rubber roller (not shown) provided at the lower end of the rotating shaft (3a) of the mounting base (3) is attached to the support section of the turntable (7). The rubber roller connected to the shaft of the rotation motor (7e) provided in (7a) is rotatably contacted. After holding the mounting base (3) with the piston ring (1) on the support (7a) of the turntable (7), rotate the turntable (7) counterclockwise to revolve the mounting base (3). The mounting base (3) is conveyed from the mounting stage (20) to the first heat painting stage (21).

  In the first heat painting stage (21), the piston ring (1) is rotated by the heating device (11) while rotating the piston ring (1) on the horizontal surface together with the mount (3) by driving the rotation motor (7e). One surface of the side surfaces (1a, 1b) is heated uniformly. At that time, the temperature sensor (8) measures the temperature of one of the side surfaces (1a, 1b) of the piston ring (1), and when the one side surface (1a, 1b) is heated to a predetermined temperature, the temperature sensor ( When an output signal is generated by 8) or when a certain time has elapsed after heating is started, the coating device (12) paints on one side (1a) of the piston ring (1) heated on the mounting base (3). Spray (5) and attach. In the first heat painting stage (21), the rotation motor (7e) is driven at high speed, and the piston ring (1) is rotated together with the mounting base (3), and at the same time, the first heating device (11a) is operated. Then, one side surface (1a) of the piston ring (1) is heated by the heating plate. As described above, in the first heat painting stage (21), the piston ring (1) can be continuously and automatically heated by the heating device (11c) and sprayed by the coating device (12). . When the paint (5) is applied, the first spray (12a) is rotated on one side surface (1a) of the piston ring (1) while rotating the mounting base (3) by driving the rotation motor (7e). The paint (5) is adhered and the first heat painting process is performed.

  After the completion of the first heat painting process by the first spray (12a), the turntable (7) is rotated counterclockwise to mount the mounting base from the first heat painting stage (21) to the reversing stage (23). Transport (3). In the reversing stage (23), the mounting base (3) is gripped by the robot arm (not shown) of the articulated robot of the reversing device (13), and the piston ring (1 ) And the mounting base (3) is removed, and the tip of the robot arm is rotated 180 degrees to reverse the mounting base (3), thereby reversing the top and bottom of the side surfaces (1a, 1b) of the piston ring (1), Reattach the mount (3) to the support (7a) of the turntable (7) so that it can rotate. In this case, with the mounting base (3) held on the support portion (7a), only the piston ring (1) may be removed from the mounting base (3) and turned over, and mounted on the mounting base (3) again. .

  Further, the turntable (7) is rotated counterclockwise, and the mounting base (3) is conveyed from the reversing stage (23) to the second heat painting stage (22), and the second heat painting stage (22). The other side surface (1b) of the piston ring (1) is heated by the second heating plate (11b) of the heating device (11) while rotating the mounting base (3) by driving the motor (7e) for rotation. Then, the paint (5) is attached to the other side surface (1b) by the second spray (12b), and the second coating is performed in the same manner as the first coating process in the first heat painting stage (21). Perform the process. After finishing the second painting process, turn the turntable (7) counterclockwise to transport the mounting base (3) from the painting stage (22) to the removal stage (24), Remove the piston ring (1) painted 1b) from the mounting base (3) by the ring removal device (14), drive the conveyor (14a) and move the ring removal device (14) in the direction of the arrow The piston ring (1) is carried out of the device.

  Then, the turntable (7) is rotated, and the mounting base (3) from which the painted piston ring (1) has been removed is transported from the removal stage (24) to the cleaning stage (25), and the motor for rotation (7e ), The mounting base (3) is rotated by the cleaning device (15) while rotating the mounting base (3). Therefore, in the present invention, the side surface of the piston ring (1) can be continuously and automatically painted. In addition, the coating conditions for each of the first and second heat painting stages (21, 22) are individually set, and the thickness and type of the coating on the side surfaces (1a, 1b) of the piston ring (1) are set. Can be combined freely. If only one side (1a, 1b) is painted and there is no need to coat both sides (1a, 1b), one of the first and second heat-coating stages (21, 22) can be omitted. If so, the coating apparatus of the present invention can be used. Since both sides (1a, 1b) of the piston ring (1) are applied from the same direction under the influence of the same gravity, it is possible to form the same quality coating (2a, 2b) as shown in FIG. it can. Therefore, since the paint (5) can be reliably applied to the side surfaces (1a, 1b) of the piston ring (1) heated to the optimum temperature, the coating film firmly adheres to the surface of the piston ring (1), Good adhesion and improved yield are obtained. In addition, since the coating flow due to the temperature drop of the piston ring (1) or the variation in coating thickness due to non-uniform temperature can be suppressed, good coating quality can be obtained in terms of film thickness and appearance. The piston ring (1) is attached to the mounting base (3) so that it can rotate, and the mounting base (3) is attached to the support part (7a) of the turntable (7) so that it can revolve, and the mounting base (3) is attached to the turntable. (7) Revolving on top, the piston ring (1) can be continuously painted and reversed.

  In general coating, if the preheating temperature of an object to be coated is too high, solvent evaporation occurs instantaneously on the base, and the adhesion of the coating film decreases. In addition, bubbles generated inside the coating film increase, and a porous coating film or a coating film with poor surface roughness is formed. Furthermore, since there is a risk of ignition, preheating is not performed much. As shown in FIG. 1, when the heating device (11) and the coating device (12) are provided in the same housing (30, 31), the piston ring (1 ) Can be maintained at a substantially constant temperature, and the desired effect can be obtained. In addition, a temperature sensor (8) that measures the temperature of the side surfaces (1a, 1b) of the piston ring (1) is provided on the painting stage (22), and the side surfaces (1a, 1b) of the piston ring (1) are kept at a predetermined temperature. If application is started when it reaches or after a certain period of time has elapsed since the start of heating, the temperature of the piston ring (1) at the start of application is surely kept within a certain range, and variations in adhesion of the paint film are reduced. be able to. The temperature measurement value of the temperature sensor (8) decreases momentarily when the mating part of the piston ring (1) passes, so the mating part of the piston ring (1) is measured by the temperature sensor (8). Since the accurate temperature of the piston ring (1) is not displayed when passing through the location, the output control of the heating device (11) by the temperature sensor (8) is not performed. When application is started based on the temperature measured by the temperature sensor (8), when the average temperature excluding the temperature measurement value at the junction reaches the preset coating start temperature (desirably 40-60 ° C) Start painting. Also, when starting application based on a preheating time that is determined in advance, because the reached temperature differs depending on the temperature of the piston ring (1) before preheating, the temperature of the piston ring (1) is changed, and a preheating experiment is performed in advance. It is necessary to obtain in advance the preheating conditions at which the piston ring (1) reaches an optimum temperature (desirably 40-60 ° C.) at the start of coating, that is, the output of the heating device (11) and the preheating time.

  In the piston ring side surface painting method of the present invention, the first and second heat application stages (21, 22) are provided, and the turntable (7) is always continuously rotated in a certain direction, for example, counterclockwise. It is efficient to paint one side surface (1a, 1b) of the piston ring (1), reverse the piston ring (1), and perform the other side surface (1b, 1a). However, after the second heat application stage (22) is omitted and the piston ring (1) is reversed by the reversing device (13), the turntable (7) is rotated clockwise to reverse the first After returning to the heat painting stage (21) and painting the other side (1b, 1a) at the first heat painting stage (21), the piston ring (1) is attached to the mounting base (3 ) May be removed. In this case, the procedure for painting the side of the piston ring is as follows: <1> Attach the mounting base (3) to each of the multiple support parts (7a) provided on the turntable (7), and <2> Attach the piston ring (1) to the mounting base (3) at the removal stage, revolve the <3> turntable (7) on the horizontal surface, and mount the mounting base (3) from the mounting removal stage to the heat painting stage (21). <4> Heat one side (1a, 1b) of the piston ring (1) while rotating the piston ring (1) on the horizontal surface together with the mounting base (3) on the heat painting stage (21). When one side surface (1a, 1b) is heated to a predetermined temperature, paint (5) is applied to one side surface (1a, 1b), and <5> the turntable (7) is revolved on a horizontal plane. Then, move the mounting base (3) from the heat coating stage to the reversing stage (23) and stop the rotation of the piston ring (1). The piston ring (1) is turned upside down with the side surfaces (1a, 1b) of the bracket (1) turned upside down and held on the support (7a) of the turntable (7) via the mounting base (3). 7> Revolve the turntable (7) in the opposite direction, and return the mounting base (3) from the reversing stage (23) to the heat painting stage (21), and <8> the mounting base (3 ) And the other side surface (1b, 1a) of the piston ring (1) is heated while rotating the piston ring (1) on a horizontal plane, and the other side surface (1b, 1a) is heated to a predetermined temperature. Apply the paint (5) to the other side (1b, 1a), revolve the <9> turntable (7) in the reverse direction, and attach the mounting base (3 ) And the rotation of the mounting base (3) is stopped. Finally, the piston ring (1) is removed from the mounting base (3) by the <10> ring mounting removal stage.

  It has a nominal outer diameter of 82mm, a thickness of 1.2mm, and a width of 2.5mm. The outer peripheral sliding surface is chrome-plated, and both sides (1a, 1b) of the piston ring (1) are coated with manganese phosphate. A piston ring (1) made of mild steel, which was pre-formed with a treatment (RPK-27), was mounted on the turntable (7). Oil tempered wire for valve spring (SWOSC-V) steel plate (SP-2) was used for the material of piston ring (1). Using the horizontal coating device shown in Fig. 1 in which the turntable (7) rotates on a horizontal plane, the polyamideimide resin film in which molybdenum disulfide, graphite, etc. are dispersed in the film is applied to both sides (1a) of the piston ring (1). , 1b). Turntable (7) rotation speed during painting: 140 rpm, induction heating output: 55%, maximum output: 5.6 kW, heating time: 6 seconds, spray gun: Fuso Seiki Lumina ST-6SK-0.5, nozzle opening: 18, spraying distance: 60 mm, spraying air pressure: 0.4 MPa, coating time: 6 seconds, coating start temperature: 50 ° C., coating end temperature: 150-160 ° C.

  At the same time that the piston ring (1) was rotated at 215 rpm together with the mounting base (3), the heating device (11) was operated, and the piston ring (1) was heated by the heating plate of the first heating device (11a). When about 1 second passed after the start of heating, application of the paint (5) supplied from the paint tank (4) was started by the first spray (12a) of the coating apparatus (12), and the application was performed for about 4 seconds. The side surface temperature of the piston ring (1) measured by the temperature sensor (8) was about 50 ° C. at the start of coating and about 56 ° C. at the end of coating. The piston ring (1) painted on one side (1a) is transferred from the reversing stage (23) to the painted stage (22) on the other side (1b), and the piston ring is measured by the temperature measured by the temperature sensor (8). When (1) reaches about 50 ° C, the other side surface (1b) of the piston ring (1) is moved by the second heating plate (11b) in the same manner as the coating stage (22) on one side surface (1a). The other side surface (1b) from the second spray (12b) was painted by heating. The moving time of the turntable (7) rotated in accordance with the operation time of the painting stage (22) requiring the longest time was approximately 8 seconds.

  The film thickness, film adhesion and appearance of about 100 piston rings (1) in which a polyamideimide film containing a solid lubricant was formed on both sides (1a, 1b) by the coating method of Example 1 were inspected. No defects were observed.

  The present invention can be satisfactorily applied to a coating apparatus that applies a paint to both surfaces of an object to be coated.

The top view which shows 1st Embodiment of the piston ring side surface coating apparatus by this invention The perspective view which shows the heat application | coating stage of FIG. Cross section of piston ring after painting

Explanation of symbols

  (1) ・ ・ Piston ring, (1a) ・ ・ One side, (1b) ・ ・ The other side, (1c) ・ ・ Outer surface, (1d) ・ ・ Inner surface, (2a, 2b) ・ ・Coating film, (3) ・ ・ Mount, (3a) ・ ・ Rotating shaft, (3b) ・ ・ Header, (3c) ・ ・ Spoke, (4) ・ ・ Paint tank, (5) ・ ・ Paint, (6・ ・ Nozzle device, (7) ・ ・ Turntable, (7a) ・ ・ Supporting part, (7b) ・ ・ Outer peripheral part, (7c) ・ ・ Revolving shaft, (7d) ・ ・ Arm, (7e) ・ ・Rotating motor, (8) ・ ・ Temperature sensor, (9) ・ ・ Ring conveying device, (9a) ・ ・ Conveying conveyor, (10) ・ ・ Ring mounting device, (10a) ・ ・ Conveying conveyor, (11) ・· Heating device, (11a) · · First heating device, (11b) · · Second heating device, (12) · · Coating device, (12a) · · First spray, (12b) · · 2 sprays, (13) ・ ・ Inversion device, (14) ・ ・ Ring removal device, (14a) ・ ・ Conveyor, (15) ・ Cleaning (20) ・ ・ Installation stage, (21) ・ ・ First heat painting stage, (22) ・ ・ Second heat painting stage, (23) ・ ・ Reversing stage, (24) ・ ・ Removal stage, (25) ・ ・ Washing stage,

Claims (6)

A turntable having an outer peripheral portion provided with a plurality of support portions and arranged rotatably around a vertical revolution axis on a horizontal plane;
A mounting base mounted on each support portion of the turntable and supporting the piston ring so as to be rotatable on a horizontal plane around a vertical rotation axis;
A heating device that heats a side surface of the piston ring supported by a mounting base that rotates around a rotation axis;
A coating device for applying paint to the side of the heated and rotating piston ring;
A reversing device that removes the mounting base together with the piston ring from the support part of the turntable, reverses the side of the piston ring by reversing the mounting base, and then mounts the mounting base together with the piston ring on the support part of the turntable A piston ring side surface painting apparatus comprising: The turntable includes a plurality of arms extending radially outward from the revolution axis at a constant angular interval, and a support portion provided on the outer peripheral portion of each arm,
The mounting base is a rotating shaft that is rotatably and vertically supported by the support portion, a header provided at one end of the rotating shaft, and is attached to the header by extending radially outward from the header, and the piston ring is detachable The piston ring side surface coating apparatus according to claim 1, comprising a plurality of spokes that can be attached. A ring mounting device for detachably mounting the piston ring on the mounting base;
The piston ring side surface coating apparatus according to claim 1, further comprising: a ring removing device that removes the piston ring whose side surface is coated from the mounting base. The heating device includes a first heating device provided between the ring mounting device and the reversing device, and a second heating device provided between the reversing device and the ring removing device,
4. The piston according to claim 3, wherein the coating device includes a first coating device provided between the ring mounting device and the reversing device, and a second coating device provided between the reversing device and the ring removing device. Ring side painting equipment. Mounting the piston ring on the mounting base with the ring mounting device;
Mounting a mounting base horizontally on each of a plurality of support portions provided on a turntable that has a vertical revolution axis and is disposed horizontally;
Revolving the turntable on a horizontal surface together with the mount around the revolution axis to bring the mount close to the heating device;
Heating one side surface of the piston ring supported on the mounting table by a heating device while rotating the mounting table together with the piston ring on a horizontal plane around a vertical rotation axis;
Applying paint to one heated side of the rotating piston ring;
Revolving the turntable on a horizontal plane, bringing the mounting base close to the reversing device together with the piston ring, and stopping the rotation of the mounting base;
The reversing device takes out the mounting base together with the piston ring from the support part of the turntable, and reverses the side of the piston ring by reversing the mounting base. Mounting process;
Revolving the turntable around a revolution axis on a horizontal plane and bringing the inverted mounting base closer to the heating device;
Heating the other side surface of the piston ring supported on the mounting table by a heating device while rotating the mounting table together with the piston ring on a horizontal plane around a vertical rotation axis;
Applying paint to the other heated side of the rotating piston ring;
Revolving the turntable on a horizontal surface, bringing the mounting base closer to the ring removal device, and stopping the rotation of the mounting base;
Removing the piston ring from the mounting base by the ring removing device. Revolving the turntable on a horizontal surface around the revolving axis together with the mounting base to bring the mounting base closer to the first heating device;
Heating one side surface of the piston ring supported by the mounting base by the first heating device while rotating the mounting base together with the piston ring around a vertical rotation axis;
Applying paint to one heated side of the rotating piston ring;
Reversing the side of the piston ring upside down by a reversing device, revolving the turntable on a horizontal plane around the revolving axis, and bringing the reversed mounting base closer to the second heating device;
Heating the other side surface of the piston ring supported by the mounting table by the second heating device while rotating the mounting table together with the piston ring on a horizontal plane around a vertical rotation axis;
6. A piston ring side surface coating method according to claim 5, further comprising a step of applying a paint to the other heated side surface of the rotating piston ring.

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