Coating device and coating method

Abstract

To provide a coating device and a coating method which can coat a screw part with process liquid selectively and easily.SOLUTION: A coating device 10, which coats a screw part 23 of a work-piece 20 having the screw part 23 with process liquid 30, comprises a supply mechanism 11 that supplies the process liquid 30 onto the screw part 23 of the work-piece 20, and a holder 12 that rotates the work-piece 20 with an axis Ax of the screw part 23 as a center while holding the work-piece 20. The coating method comprises a supply step of supplying the process liquid 30 onto the screw part 23 of the work-piece 20, and a rotating step of rotating the work-piece 20 with the axis Ax of the screw part 23 as a center.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a coating device and a coating method for coating a treatment liquid onto a threaded portion of a workpiece having a threaded portion. [Background technology]

[0002] As a workpiece having a threaded portion, for example, a bolt or a screw has a shaft on which the threaded portion is threaded and a head provided at the base end of the shaft, and the head has a recess for fastening formed in a shape such as a line, cross, hexagon, or star. The threaded portions of such bolts and screws may be subjected to a surface treatment in which a treatment liquid is applied to them for purposes such as stabilizing the coefficient of friction, preventing loosening, preventing rust, providing insulation, improving adhesion, and protecting the surface. For example, a method of this surface treatment is proposed, as disclosed in Patent Document 1. The method disclosed in Patent Document 1 involves immersing a basket-shaped container for holding bolts and screws in a processing solution, attaching the container to a centrifuge, applying centrifugal force to the bolts and screws to shake off excess processing solution, and then rotating the container substantially 180° in a plane perpendicular to the rotation axis of the centrifuge and applying centrifugal force again to shake off any processing solution remaining in the recesses. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-210404 Summary of the Invention [Problem to be solved by the invention]

[0004] The purpose of Patent Document 1 is to prevent the treatment liquid from remaining in the recess and filling the recess. In other words, many workpieces with threads, like this recess, have areas where application of the treatment liquid is restricted or prohibited from the standpoint of precision (hereinafter also referred to as "non-coated areas"), and dealing with these non-coated areas presents a problem during surface treatment. In particular, some workpieces have non-coated areas located close to or adjacent to the threads. For such workpieces, complex procedures are required, such as masking the non-coated areas in advance to prevent the treatment liquid from adhering to the non-coated areas or manually selectively applying the treatment liquid to the threads, making surface treatment extremely difficult.

[0005] The present invention has been made in view of the above problems, and has an object to provide a coating device and a coating method that can selectively and easily apply a treatment liquid to a threaded portion. [Means for solving the problem]

[0006] The present invention provides the following means for solving the above problems. [1] The coating device of the present invention is a coating device that coats a treatment liquid on a threaded portion of a workpiece having a threaded portion, a supply mechanism for supplying the processing liquid onto the threaded portion of the workpiece; The gist of the present invention is that it comprises a holder that holds the workpiece and rotates it around the axis of the threaded portion. [2] In the coating device of the present invention, the supply mechanism can drop the treatment liquid in the form of droplets onto the screw portion. [3] The coating device of the present invention may further include a guide that slides against the threaded portion. [4] In the coating device of the present invention, the supply mechanism may include a position changing means for changing the supply position of the treatment liquid on the screw portion. [5] In the coating device of the present invention, the workpiece may have a non-coated portion adjacent to the screw portion, where coating of the treatment liquid is suppressed or prohibited. [6] The coating method of the present invention is a coating method for coating a treatment liquid onto a threaded portion of a workpiece having a threaded portion, a supplying step of supplying the processing liquid onto the threaded portion of the workpiece; The method also includes a rotating step of rotating the workpiece around the axis of the threaded portion. [7] In the coating method of the present invention, the viscosity of the treatment liquid may be less than 1000 mPa·s. [8] In the coating method of the present invention, the rotation speed of the work is 1 min -1 (1 rpm) or more, 700 min -1 (700 rpm) or less. [9] In the coating method of the present invention, in the supplying step, a position where the treatment liquid is supplied onto the screw portion is defined as a coating start position, In the rotation process, the workpiece can be rotated in the screwing direction of the threaded portion to coat the area from the coating start position on the threaded portion to the base end of the threaded portion with the treatment liquid, or the workpiece can be rotated in the screwing retraction direction of the threaded portion to coat the area from the coating start position on the threaded portion to the tip end of the threaded portion with the treatment liquid. [Effects of the Invention]

[0007] According to the coating device and coating method of the present invention, the treatment liquid can be selectively and easily applied to the threaded portion. [Brief explanation of the drawings]

[0008] The present invention will be further described in the following detailed description, which provides non-limiting examples of exemplary embodiments according to the present invention, and with reference to the mentioned drawings, in which like reference numerals refer to like parts throughout the several views of the drawings. [Figure 1] 1 is a perspective view illustrating an example of a coating device of the present invention. [Figure 2] FIG. 10 is a front view illustrating an example of a supplying step of the present invention. [Figure 3] FIG. 10 is a front view illustrating another example of the supplying step of the present invention. [Figure 4] FIG. 10 is a front view illustrating an example of a rotation process of the present invention. [Figure 5] FIG. 10 is a front view illustrating another example of the rotation process of the present invention. [Figure 6] 1A and 1B are a cross-sectional view and a plan view, respectively, illustrating the movement of a treatment liquid on a threaded portion of the present invention. [Figure 7] 10(a) and 10(b) are front views illustrating a modified example of the workpiece of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will now be described with reference to the drawings. The matters set forth herein are intended to exemplify and exemplify embodiments of the present invention, and are set forth in order to provide what is believed to be the most effective and easily understandable explanation of the principles and conceptual features of the present invention. In this regard, it is not intended to show structural details of the present invention beyond the extent necessary for a fundamental understanding of the present invention, and the description, taken in conjunction with the drawings, will make clear to those skilled in the art how some aspects of the present invention can be actually embodied.

[0010] [1] Coating equipment The coating device (10) of the present invention is a coating device that coats a treatment liquid (30) onto a threaded portion (23) of a workpiece (20) having the threaded portion (23), a supply mechanism (11) that supplies the processing liquid (30) onto the threaded portion (23) of the workpiece (20); and a holder (12) that holds the work (20) and rotates it around the axis (Ax) of the threaded portion (23).

[0011] The coating device 10 illustrated in FIG. 1 is configured to coat a treatment liquid onto a workpiece 20 having a threaded portion 23 as a coating target. The coating device 10 includes a supply mechanism 11 and a holder 12 . The supply mechanism 11 is for supplying the processing liquid onto the threaded portion 23 of the workpiece 20 . The holder 12 is for holding the workpiece 20 and is configured to rotate the workpiece 20 around the axis Ax of the threaded portion 23 of the workpiece 20 . The coating device 10 may further include a guide 13 that is in sliding contact with the threaded portion 23 .

[0012] In the following description, directions are referred to using the x, y, and z arrows shown in FIG. 1 as references, with the x direction being the upward direction, the y direction being the tip direction, and the z direction being the front direction. The direction opposite to the x direction is the downward direction, the direction opposite to the y direction is the proximal direction, and the direction opposite to the z direction is the rearward direction.

[0013] (1) Supply mechanism The supply mechanism 11 can have a nozzle 111 that supplies the treatment liquid to the threaded portion 23 of the workpiece 20 in order to apply the treatment liquid to the threaded portion 23 (see FIG. 1, etc.). The nozzle 111 is formed in a pipe shape and is disposed so as to extend in a direction perpendicular to the axis Ax of the threaded portion 23 of the workpiece 20, specifically in the vertical direction. The nozzle 111 has an opening at the lower end (nozzle tip side) in FIG. 1 that serves as a discharge port (not shown) for the processing liquid. The lower end of the nozzle 111 is formed in a shape in which the diameter decreases as it goes downward, that is, the diameter decreases as it approaches the discharge port.

[0014] Although not shown, the supply mechanism 11 includes a tank in which the processing liquid is stored, and a supply system that connects the tank and the nozzle 111 in addition to the nozzle 111 . The nozzle 111 is disposed above the workpiece 20 with the outlet at the bottom facing downward so that the outlet faces the workpiece 20 .

[0015] In the supply mechanism 11 , the processing liquid is sent to the nozzle 111 from a tank via a supply system, and the processing liquid is discharged from a discharge port at the lower end of the nozzle 111 toward the workpiece 20 . The lower end of the nozzle 111 is formed in a shape in which the diameter narrows as it approaches the outlet, so that the processing liquid ejected from the outlet of the nozzle 111 falls in the form of droplets onto the workpiece 20 (see Figures 2 and 4).

[0016] The supply mechanism 11 may include a position changing means for changing the supply position of the treatment liquid on the thread portion 23. The configuration of this position changing means is not particularly limited as long as it can change the supply position of the treatment liquid on the thread portion 23, but for example, it may be configured as follows. That is, the position changing means includes a rail 112 attached to the frame 10A of the coating device 10. The rail 112 is disposed above the workpiece 20 so as to extend parallel to the axis Ax of the screw portion 23. A nozzle 111 is attached to and supported on the rail 112 so as to be movable in the direction in which the rail 112 extends.

[0017] The position changing means includes a rail 112 and a movement mechanism (not shown) that moves the nozzle 111. The movement mechanism includes a drive source such as a servo motor or stepping motor, a transmission means such as a belt or wire that transmits the drive force from the drive source to the nozzle 111, an amplifier that controls the drive source, a control device such as a sequencer, and the like. The movement mechanism can move the nozzle 111 along the rail 112 and stop the movement of the nozzle 111 at a desired position.

[0018] The position changing means can move the nozzle 111 that supplies the processing liquid to the threaded portion 23 along the rail 112 by using a movement mechanism. That is, the position changing means can change the supply position of the processing liquid on the threaded portion 23 by moving the nozzle 111 along the axis Ax of the threaded portion 23.

[0019] (2) Holder The holder 12 is not particularly limited in configuration as long as it can hold the workpiece 20 and rotate the workpiece 20 around the axis Ax of the screw portion 23, but can be configured as follows, for example. The holder 12 includes a main body 121 and a clamp 122 provided on the main body 121 .

[0020] The main body 121 is formed in the shape of a circular plate when viewed from the direction of the axis Ax of the threaded portion 23 of the workpiece 20. The main body 121 is attached to a frame 10A of the coating device 10. A drive source (not shown) such as a motor is connected to the main body 121. The main body 121 can be driven to rotate around the axis Ax of the threaded portion 23 of the workpiece 20 by this drive source.

[0021] A plurality of clamps 122 (three in FIG. 1) are provided so as to protrude from one surface of the main body 121 toward the workpiece 20 in a claw-like shape. These clamps 122 fix the workpiece 20 to the main body 121 by clamping the end (head 22) of the workpiece 20 between them. The multiple clamps 122 are arranged at equal intervals with respect to the rotation center of the main body 121. Therefore, by fixing the workpiece 20 to the main body 121 so as to surround the end portion (head 22) of the workpiece 20 with the multiple clamps 122, it is possible to align the axis Ax of the screw portion 23 of the workpiece 20 with the rotation center of the holder 12 (main body 121).

[0022] The holder 12 can switch the direction of rotation of the workpiece 20 caused by the rotational drive of the main body 121 between the screw-in direction of the screw portion 23 and the screw-retract direction of the screw portion 23. The screwing direction of the threaded portion 23 is the direction in which the threaded portion 23 tightens, and the screwing retraction direction of the threaded portion 23 is the direction in which the threaded portion 23 loosens.

[0023] Specifically, if the screw portion 23 is a right-handed screw, the screw-in direction is clockwise (right-handed) when the screw portion 23 is viewed from the base end toward the tip end, and the screw-out direction is counterclockwise (left-handed) when the screw portion 23 is viewed from the base end toward the tip end. Furthermore, if the screw portion 23 is a left-handed screw, the screw-in direction is counterclockwise (left-handed) when the screw portion 23 is viewed from the base end toward the tip end, and the screw-out direction is clockwise (right-handed) when the screw portion 23 is viewed from the base end toward the tip end.

[0024] (3) Guide The guide 13 is not particularly limited in configuration as long as it can slide against the threaded portion 23 of the workpiece 20, but for example, it can have the following configuration. The guide 13 is formed in a thin plate shape and is attached to the frame 10A of the coating device 10. The guide 13 is disposed on the front side of the workpiece 20, and its surface is in sliding contact with the threaded portion 23 of the workpiece 20.

[0025] When the coating device 10 applies the treatment liquid to the threaded portion 23 of the workpiece 20, the guide 13 is brought into sliding contact with the threaded portion 23, thereby spreading the treatment liquid supplied to the threaded portion 23 between the surface of the threaded portion 23 and one side of the guide 13. That is, the guide 13 can spread the treatment liquid over the surface of the threaded portion 23, thereby shortening the work time required for application.

[0026] There is no particular limitation on the material of the guide 13. Specific examples of the material include metals such as iron, aluminum, and copper, and synthetic resins such as polyethylene, polypropylene, polyethylene terephthalate, polyamide, polycarbonate, and fluororesin. The size of the guide 13 is not particularly limited as long as it corresponds to the size of the threaded portion 23. Specifically, the size of the guide 13 can be set to a size corresponding to the length of the threaded portion 23 in the direction of the axis Ax.

[0027] (4) Work The workpiece to be applied to the coating device of the present invention will now be described. The workpiece 20 is not particularly limited in use, shape, size, etc., as long as it has a threaded portion 23. The threaded portion 23 may be either an external thread formed on the outer periphery of the workpiece 20 or an internal thread formed on the inner periphery of the workpiece 20, but is preferably an external thread. Specific examples of the workpiece 20 include fastening members for fastening two or more fastened members, such as bolts and screws, and joined members such as union bolts, cylinder rods, valve stems, and handle stems, which are themselves connected, joined, or otherwise joined to other members via threaded portions.

[0028] The threaded portion 23 can be provided over substantially the entire shaft portion 21 of the workpiece 20, as in a fastening member, or can be provided only on a portion of the shaft portion 21 of the workpiece 20, as in a member to be joined. The threaded portion 23 may be formed as either a right-handed thread or a left-handed thread, and is not particularly limited. A right-handed thread is one in which the screw grooves and threads are formed along a helix that extends in a right-handed (clockwise) spiral toward the tip, while a left-handed thread is one in which the screw grooves and threads are formed along a helix that extends in a left-handed (counterclockwise) spiral toward the tip.

[0029] The coating device 10 of the present invention can selectively coat the treatment liquid only onto the threaded portion 23 of the workpiece 20. For this reason, the workpiece 20 to be subjected to the coating device 10 is preferably one in which the threaded portion 23 is provided only on a part of the shank of the workpiece 20, such as a member to be joined. The workpiece 20 having the threaded portion 23 may have a non-coated portion 24 where application of the treatment liquid is suppressed or prohibited from the viewpoint of accuracy. The non-coated portion 24 may be located in a position close to or adjacent to the threaded portion 23 where the treatment liquid is applied. As described above, the coating device 10 can selectively coat the treatment liquid only on the threaded portion 23. For this reason, the workpiece 20 used in the coating device 10 is useful if the non-coated portion 24 is located near or adjacent to the threaded portion 23, and in particular, if the non-coated portion 24 is located adjacent to the threaded portion 23, it is useful from the viewpoint of reliably preventing the treatment liquid from being applied to the non-coated portion 24.

[0030] The workpiece 20 shown in FIG. 1 has a round bar-shaped shaft portion 21 and a hexagonal head portion 22 provided at the base end of the shaft portion 21. The threaded portion 23 is provided in the middle portion of the shaft portion 21 of the workpiece 20. Specifically, the threaded portion 23 is formed as an external thread on the outer periphery of the middle portion of the shaft portion 21. The threaded portion 23 is a right-handed screw, and a thread 231 and a thread groove 232 are formed along a helix that extends toward the tip while drawing a right-handed (clockwise) spiral. The workpiece 20 has non-coated portions 24 where application of the treatment liquid is suppressed or prohibited on the outer periphery of the base end and tip end of the shaft portion 21. These non-coated portions 24 are arranged in positions adjacent to the thread portion 23.

[0031] There is no particular limitation on the material of the workpiece 20. Specific examples of this material include iron, steel, aluminum, magnesium, copper, titanium, stainless steel, brass, duralumin, Inconel, and synthetic resins (plastics, engineering plastics). The treatment liquid applied to the threaded portion 23 of the workpiece 20 is not particularly limited and may be selected depending on the purpose of the surface treatment. Specific examples of the treatment liquid include anti-corrosion agents, anti-wear agents, anti-sliding agents, anti-noise agents, rust inhibitors, heat-resistant paints, friction coefficient stabilizers, friction reducers, and insulating agents.

[0032] There is no particular limitation on the size of the threaded portion 23. As the size of the threaded portion 23, the thickness (nominal diameter; outer diameter of the thread 231) is not particularly limited, and can be, for example, 3 mm to 80 mm, preferably 5 mm to 50 mm, and more preferably 8 mm to 20 mm. Furthermore, the size of the screw portion 23, namely, the length (the length from the base end to the tip end of the screw portion 23 on the shaft portion 21), is not particularly limited, and can be, for example, 1 mm to 500 mm, preferably 5 mm to 300 mm, and more preferably 8 mm to 100 mm. As for the size of the threaded portion 23, the pitch (the distance between the threads 231 or between the thread grooves 232) can be set to 0.1 mm to 5 mm, preferably 0.2 mm to 3 mm, and more preferably 0.3 mm to 1 mm.

[0033] The workpiece 20 is not limited to a configuration having only one screw portion 23 as illustrated in Figure 1, but can also be configured to have two or more screw portions, for example, as in the workpiece 20 shown in Figures 7(a) and (b). 7(a) is provided with a first threaded portion 23A at the base end of a shaft portion 21, and a second threaded portion 23B at the tip end of the shaft portion 21. Both the first threaded portion 23A and the second threaded portion 23B are formed with right-handed threads. An uncoated portion 24 is defined between the first threaded portion 23A and the second threaded portion 23B. The workpiece 20 illustrated in Fig. 7(b) has a first threaded portion 23A provided at the base end of a shaft portion 21, and a second threaded portion 23B provided at the tip end of the shaft portion 21. The first threaded portion 23A is formed with a right-handed thread. The second threaded portion 23B is formed with a left-handed thread and is formed so as to have a smaller diameter (nominal diameter) than the first threaded portion 23A. An uncoated portion 24 is defined between the first threaded portion 23A and the second threaded portion 23B.

[0034] [2] Coating method The coating method of the present invention is a coating method for coating a treatment liquid (30) onto a threaded portion (23) of a workpiece (20) having the threaded portion (23), the coating method comprising: a supplying step of supplying the treatment liquid (30) onto the threaded portion (23) of the work (20); and a rotating step of rotating the workpiece (20) around the axis (Ax) of the threaded portion (23).

[0035] In the coating method of the present invention, a coating apparatus 10 as shown in FIG. 1 can be used. That is, the supplying step can be performed using the supply mechanism 11 of the coating device 10, and the rotating step can be performed using the holder 12 of the coating device 10.

[0036] (1) Supply process The supplying step is a step of supplying the processing liquid 30 onto the threaded portion 23 of the workpiece 20 . Specifically, as shown in Figures 2 and 3, the supplying step can be carried out by using the supplying mechanism 11 of the coating device 10 to drip the treatment liquid 30 from the nozzle 111 onto the threaded portion 23 of the workpiece 20. In this supplying step, the treatment liquid 30 is applied to the threaded portion 23, with the position where it is supplied (dropped) onto the threaded portion 23 being set as the application start position S1.

[0037] The coating start position S1 is not particularly limited and can be the end of the base end or tip end of the screw portion 23, or it can be the center of the middle part of the screw portion 23, or a position closer to the base end or tip end. Typically, when the treatment liquid 30 is to be applied to the entire thread portion 23, the application start position S1 is the end portion on the base end side or the tip end side of the thread portion 23. When the treatment liquid 30 is to be applied to only a part of the thread portion 23, the application start position S1 is the middle portion of the thread portion 23.

[0038] When the coating start position S1 is set to the end of the threaded portion 23, the base end or the tip end is selected depending on the rotation direction of the workpiece 20 in the rotation step. As illustrated in Figure 2, when the screw portion 23 is formed as a right-handed screw and the workpiece 20 is rotated clockwise (right rotation), the workpiece 20 is rotated in the screwing direction of the screw portion 23, and in this case, the coating start position S1 is the end portion on the tip side of the screw portion 23. Also, as illustrated in Figure 3, when the screw portion 23 is formed as a right-handed screw and the workpiece 20 is rotated counterclockwise (left rotation), the workpiece 20 is rotated in the screw-retracting direction of the screw portion 23, and in this case, the coating start position S1 is the end portion on the base end side of the screw portion 23.

[0039] That is, when the workpiece 20 is rotated in the screwing direction of the screw portion 23 (the direction in which the screw portion 23 tightens the screws) during the rotation process, the processing liquid 30 supplied onto the screw portion 23 is propelled toward the base end, so the coating start position S1 is the end portion on the tip side of the screw portion 23 (see Figure 2). Furthermore, when the workpiece 20 is rotated in the direction of retraction of the screw portion 23 (the direction of loosening the screw by the screw portion 23) during the rotation process, the processing liquid 30 supplied onto the screw portion 23 is propelled toward the tip side, so the coating start position S1 is the end portion on the base end side of the screw portion 23 (see Figure 3). In addition, when the screw portion 23 is formed as a left-handed screw, the screw-in direction of the screw portion 23 is the direction in which the workpiece 20 rotates counterclockwise (left rotation), and the screw-out direction of the screw portion 23 is the direction in which the workpiece 20 rotates clockwise (right rotation).

[0040] In the supplying step, there is no particular limitation on the amount of treatment liquid 30 supplied (amount dripped) onto the screw portion 23. This amount of supply (amount dripped) can be adjusted by the amount of treatment liquid sent from the tank to the nozzle 111 via the supply system in the supply mechanism 11 of the coating device 10. Specifically, the supply amount (drop amount) of the treatment liquid 30 is adjusted appropriately depending on the size of the threaded portion 23 and can be set to, for example, 0.01 g to 0.5 g. The supply amount (drop amount) can be more preferably set to 0.03 g to 0.3 g, and even more preferably set to 0.05 g to 0.2 g.

[0041] (2) Rotation process The rotating step is a step of rotating the workpiece 20 around the axis Ax of the threaded portion 23. Specifically, the rotation process can be carried out by using a holder 12 of a coating device 10, holding the workpiece 20 on the holder 12, and rotating the holder 12, as shown in Figures 4 and 5. That is, as described above, the holder 12 of the coating device 10 is configured so that the main body 121 is connected to a drive source (not shown) and is rotatable. Therefore, the rotation step of rotating the workpiece 20 held by the holder 12 can be performed simply by fixing the head 22 of the workpiece 20 to the clamp 122 and rotating the main body 121.

[0042] The timing of starting the rotation step is not particularly limited, and the rotation step can be started at any timing before the start of the supply step, during the supply step, or after the end of the supply step. That is, when the processing liquid 30 is supplied onto the threaded portion 23 in the above-mentioned supply process, specifically when the processing liquid 30 is dripped onto the threaded portion 23 from the nozzle 111, the holder 12 can be in a rotating state or in a stationary state. Typically, the rotation process is started before the supply process is started, and the holder 12 is rotated while the processing liquid 30 is dripped onto the screw portion 23 from the nozzle 111, thereby shortening the operation time.

[0043] Specifically, the rotation step can be carried out by the following operation (A) or (B). (A) As illustrated in Figure 4, the workpiece 20 is rotated in the screwing direction of the threaded portion 23, and the area from the coating start position S1 on the threaded portion 23 to the base end of the threaded portion 23 is coated with the treatment liquid 30 (see Figure 4). (B) As illustrated in Figure 5, the workpiece 20 is rotated in the direction in which the threaded portion 23 is retracted, and the area from the coating start position S1 on the threaded portion 23 to the tip of the threaded portion 23 is coated with the treatment liquid 30 (see Figure 5). That is, the rotation process can be carried out by rotating the workpiece 20 in the screw-in direction of the screw portion 23 as in (A) above, or by rotating the workpiece 20 in the screw-out direction of the screw portion 23 as in (B) above, after the above-mentioned supply process.

[0044] When the workpiece 20 is rotated in the screwing direction of the threaded portion 23 (above (A)), the coating start position S1 where the treatment liquid 30 is dropped can be the tip of the threaded portion 23. In the rotation process, the treatment liquid 30 spreads over the entire surface of the threaded portion 23 from the application start position S1 toward the base end of the threaded portion 23 (the screw retreat direction). The spreading of the treatment liquid 30 stops at the base end of the threaded portion 23 , that is, just before the non-coated portion 24 , so that the treatment liquid 30 is selectively coated only onto the threaded portion 23 .

[0045] When the workpiece 20 is rotated in the direction in which the threaded portion 23 is retracted (above (B)), the base end of the threaded portion 23 can be set as the coating start position S1 where the treatment liquid 30 is dropped. In the rotation step, the treatment liquid 30 spreads over the entire surface of the threaded portion 23 from the application start position S1 toward the tip of the threaded portion 23 (the screwing direction). The spreading of the treatment liquid 30 stops just before the tip of the threaded portion 23 , that is, the non-coated portion 24 , so that the treatment liquid 30 is selectively coated only onto the threaded portion 23 .

[0046] As described above, the details of the principle and reason why the processing liquid 30 selectively spreads only on the threaded portion 23 by rotating the workpiece 20 in the screw-in or screw-out direction of the threaded portion 23 are unknown, but the following can be considered. The following discussion will be explained using FIGS. 6(a) and 6(b) by taking as an example the case where the workpiece 20 is rotated in the screwing direction of the threaded portion 23 (above (A)). 6(a) is a schematic diagram of a cross section of the threaded portion 23 taken along a plane perpendicular to the axis Ax when viewed from the tip side of the threaded portion 23. The up-down direction in FIG. 6(a) corresponds to the up-down direction in FIG. 1 and the like. 6(b) is a schematic plan view of the screw portion 23 as seen from above. The upper side in FIG. 6(b) is the base end side of the screw portion 23, and the lower side is the tip end side of the screw portion 23.

[0047] The treatment liquid 30 dropped onto the threaded portion 23 tends to remain in place (the position where it was dropped) due to the action of surface tension, viscosity, etc., which causes adhesion to the threaded portion 23. Therefore, when viewed from the rotating threaded portion 23 (workpiece 20), the treatment liquid 30 moves as if moving in the opposite direction to the rotation direction of the workpiece 20 (see FIG. 6(a)). Furthermore, the treatment liquid 30 dropped onto the threaded portion 23 mainly enters the thread groove 232 of the threaded portion 23. Therefore, the pair of threads 231 facing each other across the thread groove 232 function as so-called guide rails, and the treatment liquid 30 that has entered the threaded groove 232 is guided in its movement relative to the threaded portion 23 so as to move along the thread groove 232 (see FIG. 6(b)).

[0048] As described above, the processing liquid 30 moves in the direction opposite to the rotation direction of the workpiece 20 when viewed from the threaded portion 23 (workpiece 20 ), and further moves along the thread groove 232 . The screw portion 23 is formed as a right-handed screw, and the thread 231 and the screw groove 232 are formed along a helix that extends in a spiral manner toward the tip end. In other words, as the screw portion 23 (workpiece 20) rotates in the screwing direction (the direction in which the screw is tightened, clockwise), the processing liquid 30 is propelled along the screw groove 232, using the screw thread 231 as a guide rail, in the screw retraction direction (towards the base end) of the screw portion 23, which is the opposite direction to the rotation direction of the screw portion 23 (workpiece 20).

[0049] As the treatment liquid 30 is propelled in the retraction direction (towards the base end) of the screw portion 23, a small amount of it is left adhering to the screw groove 232 and the thread 231, thereby spreading over the entire surface of the screw portion 23. When the treatment liquid 30 reaches the base end of the threaded portion 23, the thread 231, which serves as a guide rail for movement, ends and disappears, so that the treatment liquid 30 stops advancing and remains in place due to the action of surface tension, viscosity, etc. Therefore, the spreading of the treatment liquid 30 stops just before the end of the threaded portion 23, i.e., the non-coated portion 24, and the treatment liquid 30 is selectively coated only onto the threaded portion 23. In other words, it is considered that the processing liquid 30 dripped onto the threaded portion 23 is propelled in the opposite direction, the retraction direction (towards the base end), when the threaded portion 23 is rotated in the screwing direction (direction to tighten the screw), regardless of whether the threaded portion 23 is formed with a right-handed or left-handed thread, and is propelled in the opposite direction, the retraction direction (towards the base end), when the threaded portion 23 is rotated in the retraction direction (direction to loosen the screw).

[0050] In the rotating step, the rotation speed of the workpiece 20 is not particularly limited. Usually, the rotation speed of the workpiece 20 can be set to a level at which the processing liquid 30 supplied onto the threaded portion 23 is not shaken off and scattered. Specifically, the rotation speed is preferably 1 min -1 (1 rpm) or more, 700 min -1 The rotation speed can be set to 100 min -1 (100 rpm) or more, 600 min -1 (600 rpm or less, more preferably 200 min -1 (200 rpm) or more, 400 min -1 (400 rpm) or less.

[0051] The viscosity of the treatment liquid is not particularly limited. Typically, the viscosity of the treatment liquid can be such that it can be applied to the threaded portion 23, more specifically, such that it can adhere to and remain on the surface of the threaded portion 23 and can spread over the entire surface of the threaded portion 23. Specifically, the viscosity of the treatment liquid can be less than 1000 mPa·s, and preferably from 2 mPa·s to 800 mPa·s, and more preferably from 5 mPa·s to 600 mPa·s.

[0052] Examples of treatment liquids having a viscosity that satisfies the above range include a rust inhibitor (trade name "Geomet (registered trademark)", manufactured by MC Systems, viscosity: 515.5 mPa·s (30 rpm), 412 mPa·s (60 rpm)), a friction coefficient stabilizer (trade name "Torquer (registered trademark)", manufactured by MC Systems, viscosity: 5.6 mPa·s (30 rpm), 7.3 mPa·s (60 rpm)), and a coating agent (trade name "Metas (registered trademark)", manufactured by Yuken Kogyo Co., Ltd., viscosity: 484 mPa·s (30 rpm), 275 mPa·s (60 rpm)). The viscosity is a value measured using a rotational viscometer (TVB10 type viscometer, manufactured by Toki Sangyo Co., Ltd.) in accordance with JIS Z8803:2011 at room temperature and rotation speeds of 30 rpm and 60 rpm.

[0053] (3) Other processes The method may include other steps in addition to the feeding and rotating steps described above. Other processes include, for example, a cleaning process, which is a process before the supplying process, in which the workpiece 20 is cleaned to remove foreign matter adhering to the surface, and a film forming process, which is a process after the rotating process, in which the treatment liquid applied to the threaded portion 23 is dried, heated and dried, baked, etc. to form a film of the treatment liquid.

[0054] (4) Summary To summarize the coating method of the present invention, in the rotation process, the shape of the thread portion, the rotation direction of the workpiece, and the direction in which the treatment liquid spreads (hereinafter referred to as the "coating direction") are used in the combinations (1) to (4) in Table 1 shown below.

[0055] [Table 1]

[0056] Of (1) to (4), in (1) and (3), the treatment liquid is applied in the base end direction (the screw retreat direction), so that in the supplying step, the application start position S1 can be closer to the tip of the screw portion. On the other hand, in (2) and (4), the treatment liquid is applied in the tip direction (screw-in direction), so that the application start position S1 in the supplying step can be closer to the base end of the screw portion.

[0057] A coating method for a workpiece 20 having two or more threaded portions will be described below using a specific example. For the workpiece 20 illustrated in Figure 7(a), the first screw portion 23A and the second screw portion 23B are both right-handed in shape, so if the rotation direction of the workpiece is to be the same in the rotation step of the coating method, (1) or (2) in Table 1 can be selected and used. For the first screw portion 23A and the second screw portion 23B, when the rotation process is (1), in the supply process of the coating method, the coating start position S1 (the position where the nozzle 111 is arranged) can be S1(1) shown in Figure 7(a), that is, the tip of each of the first screw portion 23A and the second screw portion 23B. Furthermore, for the first screw portion 23A and the second screw portion 23B, when the rotation process is (2), in the supply process of the coating method, the coating start position S1 (the position where the nozzle 111 is arranged) can be S1(2) shown in Figure 7(a), that is, the base end of each of the first screw portion 23A and the second screw portion 23B.

[0058] For the workpiece 20 shown in Figure 7(b), the first screw portion 23A has a right-handed thread shape and the second screw portion 23B has a left-handed thread shape, so if the rotation direction of the workpiece is to be the same in the rotation step of the coating method, (1) and (4), or (2) and (3) in Table 1 can be used. For the first screw portion 23A, when the rotation step is (1), the coating start position S1 (the position where the nozzle 111 is disposed) in the supply step of the coating method can be S1(1) shown in Figure 7(b), i.e., the tip end of the first screw portion 23A. On the other hand, for the second screw portion 23B, when the rotation step is (4), the coating start position S1 (the position where the nozzle 111 is disposed) in the supply step of the coating method can be S1(4) shown in Figure 7(b), i.e., the base end of the second screw portion 23B.

[0059] Furthermore, for the first screw portion 23A, when the rotation step is (2), the coating start position S1 (the position where the nozzle 111 is disposed) in the supply step of the coating method can be S1(2) shown in Figure 7(b), i.e., the base end of the first screw portion 23A. On the other hand, for the second screw portion 23B, when the rotation step is (3), the coating start position S1 (the position where the nozzle 111 is disposed) in the supply step of the coating method can be S1(3) shown in Figure 7(b), i.e., the tip end of the second screw portion 23B. In the rotation process, the rotation direction of the workpiece can be arbitrarily switched during the operation. That is, (1) and (2), or (3) and (4) in Table 1 can also be performed by arbitrarily switching the rotation direction of the workpiece during the rotation process. For example, in the supply process, the coating start position S1 (the position where the nozzle 111 is disposed) can be set to the center of the thread portion 23, and in the rotation process, the treatment liquid can be first applied to the area from the center to the base end of the thread portion 23 using (1) (or (3)) in Table 1, and then the rotation direction of the workpiece 20 can be switched, and the treatment liquid can be applied to the area from the center to the tip of the thread portion 23 using (2) (or (4)) in Table 1. [Industrial Applicability]

[0060] The coating device and coating method of the present invention are widely used in surface treatment applications in which a treatment liquid is applied to a workpiece having a threaded portion. In particular, the coating device and coating method are suitable for use in surface treatment with excellent productivity, since they have the property of being able to selectively and easily apply the treatment liquid only to the threaded portion of a workpiece that has a threaded portion but also has a non-coated portion adjacent to or near the threaded portion where application of the treatment liquid is suppressed or prohibited. [Explanation of symbols]

[0061] 10; coating device, 10A; frame, 11; supply mechanism, 111; nozzle, 112; rail, 12; holder, 121; body, 122; clamp, 13; Guide, 20; workpiece, 21; shaft, 22; head, 23; threaded portion, 231; thread, 232; thread groove, 24; Non-coated part, Ax; axis line, 30; processing solution, S1: Coating start position.

Claims

1. A coating device that coats a treatment liquid on a threaded portion of a workpiece, the coating device comprising: a holder that holds the workpiece and rotates the workpiece around the axis of the threaded portion in a screw-in direction or a screw-out direction of the threaded portion; a supply mechanism for supplying the processing liquid onto the threaded portion of the workpiece, the supply mechanism includes a position changing means for changing a supply position of the processing liquid on the screw portion in accordance with a rotation direction of the workpiece, The position changing means moves the supply position closer to the tip of the screw portion when the workpiece is rotated in the screw-in direction, or moves the supply position closer to the base end of the screw portion when the workpiece is rotated in the screw-out direction.

2. The coating device according to claim 1 , wherein the supply mechanism drops the treatment liquid onto the screw portion in the form of droplets.

3. The coating device according to claim 1 or 2, wherein the workpiece has a non-coated portion adjacent to the threaded portion, where coating of the treatment liquid is suppressed or prohibited.

4. A coating method for applying a treatment liquid to a threaded portion of a workpiece using a coating device according to any one of claims 1 to 3, comprising: a rotating step of rotating the workpiece around the axis of the threaded portion in a screw-in direction or a screw-out direction of the threaded portion; a supplying step of supplying the processing liquid onto the threaded portion of the workpiece, In the supplying step, a position where the treatment liquid is supplied onto the screw portion is defined as a coating start position, and the coating start position is changed according to a rotation direction of the workpiece; When the workpiece is rotated in the screwing direction, the coating start position is set closer to the tip of the screw portion, and the range from the coating start position to the base end of the screw portion is coated with the treatment liquid, or A coating method characterized in that, when the workpiece is rotated in the screw-retraction direction, the coating start position is positioned closer to the base end of the screw portion, and the range from the coating start position to the tip end of the screw portion is coated with the treatment liquid.

5. 5. The coating method according to claim 4, wherein the viscosity of the treatment liquid is less than 1000 mPa·s.

6. The rotation speed of the workpiece is 1 min －１ (1 rpm) or more, 700 min －１ 6. The coating method according to claim 4, wherein the rotational speed is 700 rpm or less.

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