HK1051663A1

HK1051663A1 - Apparatus and method for powder coating with induction heating

Info

Publication number: HK1051663A1
Application number: HK03103874A
Authority: HK
Inventors: 吉野孝四郎; 菅沼美智雄; 小柳忠彦
Original assignee: 株式会社吉野工作所
Priority date: 2001-06-29
Filing date: 2003-05-30
Publication date: 2003-08-15
Also published as: JP4688353B2; KR100864684B1; CN1247317C; JP2003010737A; DE60201380D1; EP1270089A1; ATE277692T1; CN1393293A; DE60201380T2; KR20030004018A; EP1270089B1

Abstract

Provided is an apparatus (1) for powder coating which includes a coat-applying station (9) for applying a powder coating (P) on a work (3) to be coated, and a high frequency induction heating apparatus (47) for heating the work (3) covered with the powder coating (P) under the effect of high frequency wave and baking the powder coating (P) on the work at the interface defined between the powder coating and the work. Use of the apparatus (1) provides a uniform and strong coating film without any unevenness more efficiently with the relatively compact apparatus. <IMAGE>

Description

Powder coating device and powder coating method

Technical Field

The present invention relates to a powder coating apparatus and a powder coating method capable of forming a uniform coating film without unevenness even on a coated object (workpiece) having a complicated shape such as an iron pipe joint, and more particularly, to a powder coating apparatus and a powder coating method capable of improving adhesion of a coating film to a coated object, and increasing productivity by improving coating operation efficiency by omitting a degreasing step.

Background

In a conventional coating method, first, degreasing treatment is performed to remove foreign matter such as grease adhering to the surface of a coating object to be coated, and then, the coating, drying and baking by far-infrared light irradiation, cooling, and other steps are performed through steps such as washing, water removal, and drying.

However, since the drying and baking by far infrared irradiation is to heat the coating material from the outside, particularly, the coating material having a complicated shape tends to be baked excessively on the surface of the coating material and baked insufficiently on the surface where the coating material is fixed, and the coating film formed tends to be mottled. Further, drying and baking by far infrared ray irradiation has a drawback that the drying time is long, and if uniform drying is performed by far infrared ray irradiation, the apparatus needs to be large-sized, and it is difficult to secure the installation space, which leads to an increase in equipment cost.

In the conventional coating method, the object to be coated must be degreased before coating (painting or painting). When foreign matter such as grease is interposed between the interface between the object to be coated and the coating film by external heating such as irradiation with far infrared light, the coating film may be peeled off or the like.

However, it is considered that the degreasing treatment is performed on all the objects to be coated, which is very troublesome and greatly hinders the efficiency of the coating operation.

Further, in coating of an object to be coated, a hanger holding a plurality of objects to be coated is used, but as coating is repeated, the scattered excess paint adheres to the hanger and is firmly attached by heating, and therefore, an additional operation of peeling off the excess paint attached is necessary.

Disclosure of Invention

In view of the above-described problems, it is an object of the present invention to provide a novel and practical coating apparatus for an object to be coated and a coating method for an object to be coated, which can form a uniform and firm coating film without unevenness, can be downsized, and can further improve the efficiency of the coating operation.

In order to solve the above problem, the invention according to claim 1 provides a powder coating apparatus including: a hanger to which a hook for holding a substrate in a suspended state is attached to a plurality of horizontally arranged hook attaching rods, the hanger being made of a material that is not heated by high-frequency induction; a plurality of processing sections including a coating material application section for applying a powder coating material on the surface of an object to be coated by electrostatic coating and a heating section having 2 high-frequency induction coils disposed to face each other; a hanger transfer mechanism for sequentially transferring the hangers to the plurality of processing units and transferring the hangers to 2 high-frequency induction coils at the heating unit; the coating material is heated from the side of the object to be coated by heating the object to be coated by the high-frequency induction current supplied through the hanger.

The invention of claim 2 is the powder coating apparatus of claim 1, wherein the hanger is made of copper.

The invention according to claim 3 is the powder coating apparatus according to claim 1, wherein a conveyor device having a rotary conveyor path for rotating the object on a horizontal track is provided.

The invention of claim 4 is the powder coating apparatus according to any one of claims 1 to 3, wherein the hook for coating has a shape having a mounting portion bent in an inverted U-shape and a shank extending from one end of the mounting portion, and a plurality of vertical grooves for detachably engaging with the mounting portion are formed in the hook mounting bar in a lateral direction.

With this coating apparatus, the hook to be coated is attached to the hook attaching bar by selecting an arbitrary longitudinal groove on the hook attaching bar and hooking the attaching portion to the longitudinal groove, the position thus attached can be stably held by the attaching portion engaging into the longitudinal groove, and the attaching portion can be detached from the hook attaching bar by merely pulling the attaching portion from this state.

Therefore, the hook mounting/dismounting operation of the object to be coated with respect to the hook mounting rod can be performed by substantially 1 operation, and the operation of changing the kind or number of the object to be coated, the mounting interval in the lateral direction, etc. of the object to be coated mounted on the hook mounting rod, or partially changing the object to adjust the facing distance to the high-frequency induction coil can be completed in a short time.

The hook to be coated can be formed by processing a material which does not adhere to the powder coating, for example, a wire material such as phosphor bronze, and if the attachment portion is formed in a clip shape, the hook can be held more stably at the attachment position by the spring elasticity of the clip in a state of being hooked on the hook attachment rod.

The invention according to claim 5 is the powder coating apparatus according to claim 4, wherein the attachment portion of the hook for coating and the shank are made of a wire rod having a circular cross section, the tip of the shank extends to a position slightly lower than the attachment portion, and the tip is provided with an arrow-shaped hook portion for hanging the object to be coated.

Therefore, if the height of the shank of the hook is slightly larger than the height from the hook hole of the object to be coated to the upper end, the entire object to be coated suspended by the hook is located below the hook attaching rod when viewed from the front-rear direction, and the hook attaching rod does not hinder the coating material from being sprayed from the rear side. The attachment portion and the shank of the object hook are formed of a wire material, and the lateral width is very small, so that the spraying of the paint from the rear side is hardly hindered. Thus, coating mottle of the coating can be eliminated.

The invention of claim 6 is the powder coating apparatus according to any one of claims 1 to 3, wherein the 2 high-frequency induction coils are supported by coil holders that are movable in opposite directions relative to each other in the facing direction, and further, coil position control means for moving the coil holders is provided.

In this way, the interval between the 2 coils or the facing interval between the coil and the object can be adjusted, so that, for example, when the heating unit moves in and out of the hanger, the 2 coils are placed at the standby positions where the interval is widened, and when heating is performed, the object is controlled to move the coils to the position where the most appropriate facing interval is obtained. This makes it possible to improve versatility according to the size of the object to be coated and to set the optimum heating conditions for each object to be coated.

The invention of claim 7 is the powder coating apparatus of claim 6, characterized by comprising a marker attached to the hanger and recording data corresponding to the coil position of the high-frequency heating or proxy data based on the characteristics of the object to be coated suspended by the hanger or the paint applied to the object to be coated, a data reading circuit for reading the data recorded on the marker, a processing unit for generating a control signal based on the data read by the data reading circuit, and a control circuit for operating the coil position control mechanism of the heating unit based on the control signal.

Therefore, according to the invention of claim 7, the position of the high-frequency induction coil relative to the object to be coated, which is one of the control items for realizing the most appropriate heating depending on the characteristics of the object to be coated or the coating material, can be automatically adjusted by recording the control data or the proxy data in the marker in advance.

The invention of claim 8 is the powder coating apparatus according to any one of claims 1 to 3, including a marker attached to the hanger and recording data or proxy data of at least one of the number of times the spray gun is moved according to the characteristics of the object to be coated or the paint to be used suspended by the hanger, the amount of powder paint sprayed from the spray gun, and the heating time by the high-frequency induction coil, a data reading circuit that reads the data recorded on the marker, a processing unit that generates a control signal based on the data read by the data reading circuit, and a control circuit that operates the spray gun control means of the paint application unit and/or the coil position control means of the heating unit based on the control signal.

In the invention according to claim 8, the number of times the spray gun is moved, the amount of powder coating material sprayed from the spray gun, or the heating time by the high-frequency induction coil as at least one control item for realizing the most appropriate coating material application or heating in accordance with the characteristics of the object to be coated or the coating material can be automatically adjusted by recording the control data or the proxy data thereof in the marker in advance.

The invention of claim 9 is a powder coating method including a coating material application step of applying a powder coating material on a surface of an object to be coated by electrostatic coating and a heating step of having 2 high-frequency induction coils arranged to face each other; a hanger on which hooks for a substrate are mounted, the hooks being made of a material which is not heated by high-frequency induction and held in a suspended state by a plurality of horizontally arranged hook mounting bars, the substrate is sequentially transferred to a plurality of processing sections while being held, and transferred between 2 high-frequency induction coils in a heating section, and the substrate is heated by high-frequency induction current supplied from the hanger, thereby heating the coating material from the substrate side.

Drawings

FIG. 1 is an internal perspective view of a powder coating apparatus according to embodiment 1 of the invention,

FIG. 2 is a plan view of the powder coating apparatus of FIG. 1,

FIG. 3 is a vertical sectional side view showing the inside of a processing part for performing electrostatic powder coating in the powder coating apparatus of FIG. 1,

FIGS. 4(a) and 4(b) are views showing an outline of the powder coating apparatus of FIG. 1,

fig. 5(a) is a plan view showing 2 arrangements of the treatment sections in the powder coating apparatus according to the modification of embodiment 1 of the present invention,

FIG. 5(b) is an enlarged perspective view of an object hanger j of the powder coating apparatus in FIG. 5(a),

FIG. 6 is a plan view of the entire powder coating apparatus according to embodiment 2 of the present invention,

fig. 7 is a perspective view of a main part of the powder coating apparatus of fig. 6,

FIG. 8(a) is an enlarged partially omitted perspective view of the hanger of the powder coating apparatus of FIG. 6,

FIG. 8(b) is an enlarged perspective view of the mounting portion 108a of the powder coating device in FIG. 8(a),

FIG. 9 is a perspective view showing a state in which the object to be coated is hung on the hook of the object to be coated in the powder coating apparatus of FIG. 6,

FIG. 10 is a side view showing a state in which the object to be coated is hung on the hook of the object to be coated in the powder coating apparatus of FIG. 6,

FIG. 11 is an enlarged perspective view of a heating portion of a coating cell in the powder coating apparatus of FIG. 6,

FIG. 12 is an enlarged side view of a heating portion of a coating cell in the powder coating apparatus of FIG. 6,

FIG. 13 is an enlarged perspective view of the marker mounting portion of the hanger in the powder coating apparatus of FIG. 6,

fig. 14 is a view showing a control system of the powder coating apparatus of fig. 6.

Description of the symbols

1 powder coating device 3 coating object (workpiece) 5 working part

7 communication processing part 9 paint coating part 11 paint coating part

13 drying part 15 blowing part 17 auxiliary drying part

19 conveying device 21 conveyor 23 rotating shaft

25-rotation arm 27-arm driving motor 29 transmission mechanism

31 hanger 33 reversing motor 35 hanging rod

37 holding handle 39 paint coating portion 41 nozzle

43 recycling device 45 suction pipe 47 high-frequency induction heating device

49 high-frequency induction coil 51 notch 53 induction heating power supply device

55 blower 57 jet 59 far infrared lamp

61 cooling fan 63 receiving processing unit 65 transfer unit

101 powder coating device 103 coated object 105 hanger

107 hook mounting bar 107a longitudinal groove 108 for hook of coated object

108a mounting portion 108b handle 108c hook portion

110 marker mounting portion 125, 125' coating application portion 126 heating portion

131 main shaft 132 slewing mechanism 133 hanging bracket lifting rod

144 motor for spray gun walking 182 motor drive circuit for spray gun

151, 151' high frequency induction coil 152 coil support 155 slide block

156 guide 157 nut 158 screw

159 stepper motor 183 paint valve 184 paint valve control loop

187 coil drive circuit 187a timer 188 flag

189 data reading circuit 190 processing part P powder coating

Detailed Description

Next, a powder coating apparatus 1 according to embodiment 1 will be described with reference to fig. 1 to 4.

The powder coating apparatus 1 of the present invention is used for coating a steel coating object 3 having a complicated shape such as an iron pipe joint.

Specifically, as shown in fig. 1 and 2, the inside of the cylindrical container-shaped working section 5 is divided into 6 processing sections 7, 9, 11, 13, 15, and 17 as an example, and each of the processing sections 7, 9, 11, 13, 15, and 17 includes an additional device for performing individual processing and a conveying device 19 for holding and conveying the objects 3.

The communication processing unit 7 receives the object 3 conveyed from the outside by the conveyor 21 into the working unit, and after a series of coating operations are completed, functions again as an external communication unit that communicates with the external conveyor 21. A rotation shaft 23 is provided at the center of the working unit 5, and 6 members such as rotation arms 25 extending radially are provided at the upper part of the rotation shaft 23.

The rotation of the output shaft of the arm drive motor 27 is transmitted to the rotation shaft 23 via a suitable mechanism 29 such as a chain or a timing belt.

The free end of the rotating arm 25 is provided with a hanger 31 for holding the object 3 to be coated in a suspended state, and the hanger 31 is configured to be rotatable by a reverse motor 33, for example, by 180 degrees.

The hanger 31 is constituted by a plurality of horizontally disposed holding levers 37 provided at appropriate intervals with respect to a vertically drooping holding lever 35. The hanger 31 is formed of a material that is not heated by high frequency, such as copper.

These rotary shaft 23, rotary arm 25, drive motor 27, transmission mechanism 29, hanger 31 and conveyor 21 constitute the above-described conveying device 19.

The paint application section 9 is provided adjacent to the communication processing section 7 in the conveying direction, and the paint application section 11 is provided adjacent thereto. The structures of the paint application sections 9 and 11 are substantially the same, and these 2 members are arranged side by side in order to correspond to various kinds, small-volume production, and the like. The comb-shaped nozzles 41 of the paint application section 39 provided outside the working section 5 face the paint application sections 9, 11, respectively.

The coating material application section 39 is a device for applying the powder coating material P to the surface of the object 3 by electrostatic induction. The powder coating material P used here requires a solvent as in the case of a liquid coating material, but does not use a solvent in consideration of the fact that the solvent is a factor of environmental pollution or the like.

Further, the paint application sections 9 and 11 are connected to a suction pipe 45. The suction pipe 45 is connected to a recovery device 43 for recovering the remaining powder coating material P that is not used for coating the object 3, and a heating unit 13 for heating, solidifying, and drying the powder coating material P coated on the surface of the object 3 is provided in the conveyance direction adjacent to the coating material coating unit 11.

In the heating section 13, a high-frequency induction coil 49 having a cross section in a shape of a Chinese character 'ao' as a part of the high-frequency induction heating device 47 is provided with an opening portion facing upward so that the notch 51 can pass through the object 3 to be conveyed and the hanger 31.

The high-frequency induction coil 49 receives a current supplied from an induction heating power supply device 53 which is another part of the high-frequency induction heating device 47, and applies the high-frequency current to the object 3 to heat the powder coating material P applied to the object 3 from the inside. In order to prevent the high-frequency induction coil 49 from overheating, a pipe (not shown) through which cooling water flows is provided in the high-frequency induction coil 49.

When the coating film is formed by induction heating at a high frequency, the powder coating material P is heated from the inside, solidified, and dried. Therefore, even if a small amount of foreign matter such as grease adheres to the surface of the object to be coated 3, the foreign matter is vaporized by heating, and does not cause insufficient adhesion (adhesion) because it disappears from the interface between iron and the coating film, and a conventional degreasing treatment is not necessary.

The hanger 31 is formed of a material that is not heated by high frequency, such as copper, and the powder coating material P adhering to the surface of the hanger 31 is not heated and can be easily removed by blowing high pressure gas to the hanger 31 while it is maintained in its original state.

An air treatment section 15 is provided adjacent to the heating section 13 in the conveying direction, and removes the residual powder coating material P adhering to the surface of the coating film of the object 3 and the hanger 31. The air processing portion 15 faces the injection port 57 of the blower 55. And an auxiliary drying treatment part 17 for mainly heating the surface side of the coating film formed on the object 3 in the conveying direction adjacent to the air treatment part 15. The auxiliary drying unit 17 is provided with a plurality of 2kw far infrared lamps 59, for example, so that the coating film can be uniformly solidified and dried without unevenness. The far-infrared lamp 59 in the auxiliary drying processing section 17 is always an auxiliary function for solidifying and drying the coating film, and it is sufficient to basically solidify and dry the coating object with high frequency.

The communication processing unit 7 functioning as a communication unit for communicating with the outside described above is provided adjacent to the auxiliary drying processing unit 17 in the conveying direction. The object 3 to be coated that has entered the communication processing section 7 is sent out to the conveyor 21 located outside in a state where a coating film is formed on the surface. A cooling fan 61 is provided on the output side of the conveyor 21, and this part functions as a cooling unit. The cooling fan 61 functions to cool the object 3 and the coating film.

Next, the operation of each step of the powder coating apparatus 1 will be described.

Entering the coating into the process "

The object 3 to be coated placed on the hanger 31 is conveyed by the conveyor 21 for a predetermined distance and then conveyed into the communication processing unit 7 by a suitable conveying device. When the workpiece 3 enters the communication processing unit 7, the upper end of the hanging rod 35 of the hanger 31 is connected to the free end of the rotating arm 25, and the workpiece can be transferred to the horizontal circular track conveying path in the working unit 5.

Coating process "

The object 3 to be coated, which has entered the working section 5 through the communication processing section 7, is rotated by a predetermined angle by the rotation shaft 23 to the paint coating section 9 or the paint coating section 11. The powder coating material P supplied from the coating material application section 39 is ejected from the nozzle 41 at the coating material application sections 9 and 11, and is adsorbed and applied to the surface of the object 3 by electrostatic induction.

The hanger 31 is rotated in the reverse direction by 180 degrees by the driving of the reverse motor 33, and the powder coating material P is adsorbed and applied to the surface of the object 3 to be coated provided on the hanger 31 without fail. The remaining powder coating material P which is not adsorbed and applied to the object 3 is recovered by the recovery device 43.

High frequency induction heating process "

Subsequently, the object 3 is moved into the drying processing section 13 and is positioned in the notch 51 formed in the high-frequency induction coil 49. Here, the object 3 is heated by applying a high frequency generated by the high frequency induction coil 49 to the object 3 in response to the current supplied from the induction heating power supply 53. The powder coating material P applied to the surface of the object 3 is heated from the inside thereof with the heating of the object 3, and is solidified and dried. At the same time, foreign matter such as grease adhering to the surface of the object 3 is also vaporized by heating and disappears. Since the temperature at which the fat is gasified by heating is lower than the temperature at which the powder coating material P is solidified, the gasified fat or the like can be discharged through the powder coating material P before solidification even after the powder coating material P is applied to the object 3.

Foreign matter such as fat and oil vaporized by heating and formed into smoke is adsorbed and filtered by an adsorption filter device not shown in the figure. Thereby, the clean gas containing no foreign matter is discharged to the outside.

Air blowing process "

The object 3 to be coated on which a coating film is formed in the high-frequency induction heating step is moved into the blown air treatment section 15, and the remaining powder coating material P adhering to the surface of the coating film is blown off by the air blown from the blower 55. At the same time, the powder coating material P adhering to the hanger 31 is also blown off.

Auxiliary drying process "

Thereafter, the object 3 is fed into the auxiliary drying processing section 17 and irradiated by the far-infrared lamp 59 until auxiliary drying is performed, whereby uniform solidification and drying of the coating film without unevenness are realized.

Product output process "

Then, the object 3 is returned into the communication processing unit 7 again and conveyed to the external conveyor 21 by an appropriate transfer device. The object 3 to be coated conveyed by the conveyor 21 is cooled by the cooling air of the cooling fan 61 and is discharged as a product.

Thereafter, the objects 3 suspended by the hangers 31 are sequentially fed into the working section 5 from the conveyor 21, and are conveyed and discharged again by the conveyor 21 after going through the above-described steps.

Fig. 5(a) and 5(b) are views showing an outline of the coating apparatus 1 with particular emphasis on hooks of a coated object.

The object 3 is sequentially transferred to the paint coating section, the heating section, and the cooling section while being suspended by the hanger 31. As described above, in the coating material application sections 9 and 11, the spray gun f for spraying the electrostatically charged powder coating material P from the nozzle 41 is provided so as to be capable of reciprocating in the vertical direction, and in the heating section 13, the coil formed into an oblong spiral is bent into a U-shape to be arranged as the high-frequency induction coil 49, and in the cooling section, the air blowing fan 61 and the like are provided.

The hanger 31 is constructed such that a plurality of horizontal hook mounting bars i, on which a plurality of coated object hooks j are mounted, are mounted in the up-down direction on a longitudinal pillar h, and the hook mounting bars i are formed with a plurality of bolt through holes k in the longitudinal direction thereof. The hook j to be coated is formed in a substantially L-shape having a horizontal length by processing a band plate, the vertical portion of the hook j has a size substantially equal to the longitudinal width of the hook mounting rod i, a bolt m inserted into a hole formed in the vertical portion is inserted into any one of the bolt through holes k, and a nut p is screwed onto the bolt m on the inner side of the hook mounting rod i so as to be mounted on any position of about 2 to 3 hook mounting rods i.

The front end of the horizontal portion of the hook j to be coated is sharpened in an arrow shape, and the tip portion is inserted into the hook hole q of the hook 3 to hang the hook 3 to be coated on the hook j to be coated.

When the hanger 31 comes to the paint application section 9, the spray gun f sprays the powder paint P onto the hanger 31 while moving up and down. Thereby, the powder coating material P is applied to the object 3 by electrostatic induction.

Then, the hanger 31 is transferred between the left half g-1 and the right half g-2 of the high-frequency induction coil 49, and the object 3 hung on the hanger 31 is heated from the inside thereof. The heating is adjusted so that the temperature of the object 3 to be coated is approximately 250 to 280 ℃. Thereby, the powder coating material P applied to the object 3 is heated from the inside thereof, and the powder coating material P is baked and dried.

In the above-described embodiment, heating from the inside of the coating film can be realized by heating and drying by high-frequency induction, and the effects of shortening the drying time, downsizing the apparatus, and the like can be obtained in addition to uniform drying without unevenness.

Further, foreign matter such as grease adhering to the surface of the object 3 to be coated disappears by vaporization during high-frequency induction heating, so that a conventional degreasing treatment, which is indispensable, is not required, and the work efficiency can be greatly improved.

Further, since the coating is performed by the powder coating material P, no solvent is required for the use of the liquid coating material P, and the problem of environmental pollution does not occur. In addition, the hanger 31 is made of a material such as copper which is not heated by high frequency, and the remaining paint attached to the hanger 31 is not firmly attached because it is not heated and dried, and can be easily blown off.

Although embodiment 1 has been described in detail above, the scope of the present invention is not limited to this embodiment, and any design changes within the scope not departing from the gist of the present invention are included in the present invention.

For example, in the above embodiment, the paint application step is set to 2 steps, and the paint application sections 9 and 11 having the same configuration are arranged side by side, but it is needless to say that the paint application step is set to only 1 step, and for example, it is also possible to omit the paint application section 11, and conversely, it is also possible to add a paint application section and set the paint application step to 3 steps or more.

The interval between the notches 51 of the high-frequency induction coil 49 can be freely adjusted, so that the heating temperature can be adjusted and uniformized in the high-frequency induction heating step in accordance with the objects 3 to be coated having various sizes.

Further, if it is not necessary to pay attention to the remaining powder coating material P adhering to the surface of the coating film, the step of blowing air by the blower 55 can be omitted.

In addition, if a uniform coating film without unevenness can be formed only by the high-frequency induction heating step, the auxiliary drying step by the far-infrared lamp 59 can be omitted.

In the above embodiment, although the reception and the transfer of the object 3 to the working unit 5 are both performed in the single communication processing unit 7, the reception and the transfer can be performed by the dedicated reception processing unit 63 and the transfer processing unit 65 shown in fig. 4(a), respectively.

The conveying path of the object 3 in the working unit 5 is not limited to the rotary type shown in the above-described embodiment or fig. 4(a), and may be a linear type or a suspended type as shown in fig. 4 (b).

The movement of the object 3 is not limited to the intermittent movement, and may be a continuous movement by changing the size, the working length, and the like of each processing portion. Further, the hanger 31 may be coated with polytetrafluoroethylene or the like at a portion other than the current carrying portion, so that the cleaning operation of the hanger 31 can be facilitated.

Next, a powder coating apparatus 101 according to embodiment 2 of the present invention will be described with reference to fig. 6 to 14.

The painting apparatus 101 is configured such that a required processing portion is provided on a circumferential rail.

The object 3 to be coated is a steel pipe joint, and a hook hole 103a for coating is formed substantially at the center thereof. Needless to say, the substrate 103 is merely one of several that can be processed at the coating apparatus 101.

"A, hanger" (fig. 6-10, 12, 13)

First, a hanger 105 (see fig. 8 to 10 in detail) for hanging and conveying the object 103 to be coated will be described.

The hanger 105 is composed of a vertically long square tubular column 106, a plurality of hook attaching rods 107 attached to the column 106 in a state of being arranged at a certain interval in the vertical direction, a plurality of hooks 108 to be coated detachably attached to the hook attaching rods 107, hanging projections 109 horizontally projecting from the upper end of the column 106 to the left and right, and a marker attaching portion 110, and these members are made of a material which is not subjected to high frequency induction, for example, phosphor bronze.

Hook attaching rod 107 is a thin band plate-shaped member, and is attached to column 106 in such a manner that its width direction is vertically oriented and horizontally protrudes from the column, and one end of hook attaching rod 107 is bent at a right angle and fastened by a bolt.

On both sides in the thickness direction of the hook attaching bar 107, a plurality of vertical grooves 107a are formed at a constant pitch in the lateral direction. The vertical groove 107a is substantially V-shaped when viewed in the vertical direction, and the position of the vertical groove 107a on one side surface coincides with the position of the vertical groove 107a on the other side surface.

A plurality of such hook attaching bars 107 are provided in a vertical direction at regular intervals in a set of 2 ladder members protruding from the column 106 toward the mutually opposite sides, and the extending directions of all the ladder members are mutually identical.

The hook 108 for coating is composed of a mounting portion 108a, a shank 108b and a hook portion 108c formed by bending a wire rod having a circular cross section, and phosphor bronze is used for all of these members. The mounting portion 108a has a longitudinally elongated inverted U-shape and a width substantially equal to a thickness between longitudinal grooves 107a of a front and rear 2 hook mounting bars 107 in a set. The shank 108b extends from one end of the mounting portion 108a toward the front lower direction in a manner approximately describing a 1-out-of-4 arc, and the front end of the shank 108b is fixed to the hook portion 108 c. The hook portion 108c is formed substantially in the shape of an arrow of an equilateral triangle, and is pressed into the front end portion of the welding shank 108b through a hole formed on the side surface on the opposite side to the vertex angle thereof to be mounted on the shank 108 b.

The object hook 108 is configured such that a longitudinal groove having a pair of front and rear 2 longitudinal grooves is arbitrarily selected from a plurality of longitudinal grooves 107a formed in the hook attaching bar 107, and the attaching portion 108a is detachably attached to the hook. Thus, the hook 108 to be coated is positioned and firmly held by the engagement of the mounting portion 108a into the longitudinal groove 107a in the state of being mounted on the hook mounting bar 107.

The number of the hooks 108 to be coated attached to 1 hook attaching rod 107 is usually 2 to 3 (in fig. 6 and 7, 2 hooks are shown as an example, and in fig. 8, 3 hooks are shown as an example), but may be changed at any time according to the shape or size of the substrate.

The hanging projection 109 is a portion for hanging the hanger 105 on a hanger hanging bar described later, and is provided so as to penetrate the upper end of the column 106 in a direction parallel to the hook attaching rod 107.

The marker attachment portion 110 (see fig. 8) is a portion that is detachably fitted to a marker described later, has a short cylindrical shape, and is provided in a state of horizontally protruding from a position slightly above the hanging projection 109 in the column 106.

As the hanger used in the coating apparatus 101, any type including the illustrated hanger 105 is prepared, and the column 106 and the hook attaching rod 107 have substantially no difference in size, and the number of steps of the hook attaching rod 107 is somewhat different. In addition, a plurality of different coated hooks were prepared. The difference in kind thereof refers to the number or shape of the handles 108b, the height, the size of the hook portion 108c, and the like. The shape or size of the mounting portion 108a is common.

"B, coating Chamber" (FIG. 6, FIG. 7, FIG. 11, FIG. 12)

A coating booth is shown at 121. The coating booth 121 is a polygonal, large cylinder when viewed from above, and is substantially hermetically enclosed by a cylindrical outer wall, and various necessary accessories are provided around the outer wall.

Inside the coating booth 121, a vertically long hexagonal cylindrical spindle arrangement portion 122 is provided at the center thereof, 6 treatment portions having substantially the same size are partitioned around the spindle arrangement portion 122, and a vertically long hanger door 123 is provided on a partition wall for partitioning. The hanger door 123 is opened and closed according to the degree of the hanger 105 entering and exiting each treatment section.

The 6 processing sections are a joining section 124, 2 coating sections 125 and 125', a heating section 126, a heat equalizing section 127, and a cooling section 128, and are arranged in the above order in the clockwise direction, and the joining section 124 is adjacent to a substrate supply section described later.

The transfer portion 124 is a processing portion for transferring the hanger 105 to and from the object supply portion, the coating material application portions 125 and 125' are processing portions for applying the powder coating material P to the object 103, and the heating portion 126 is a processing portion for baking and drying the powder coating material P by heating the object 103 to which the powder coating material P is applied by high-frequency induction. The thermal equalizing section 127 is a processing section for equalizing heating by the heating section 126, and the cooling section 128 is a processing section for cooling the heated object 103.

The 2 paint coating portions 125, 125' are used separately according to the color of the paint used.

"B-1, hanger transfer mechanism" (fig. 6, fig. 7)

A vertical main shaft 131 is rotatably provided around the shaft on the aforementioned main shaft arrangement portion 122, and the main shaft 131 is intermittently rotated at an interval of 60 ° in the center angle by a rotating mechanism 132. The direction of rotation is clockwise as viewed from above.

The upper end of the main shaft 131 protrudes upward from the coating booth 121, and thereby the horizontal hanger lifting rods 133 radially protrude at 6 intervals at a central angle of 60 °. A hanger hanging member, not shown, having hanging portions for hanging the hanging projections 109 of the hanger 105 at the tip end of the hanger hanging rod 133 is provided so as to be rotatable around a vertical axis. The hanger hoisting member is rotated by a rotating mechanism 134. This rotation may reverse the direction of hanger 105.

The stop position of the intermittent rotation of the main shaft 131 is a position where the hanger lifting rod 133 comes to substantially the center of the processing units 124 to 128 shown in fig. 6 and 7, respectively.

The hanger 105 to which the target object 103 is hung on the hanger hanging member of the hanger hanging rod 133 in a hanging posture at the transfer portion 124. Therefore, the hanger 105 is transferred by the rotary main shaft 131 so as to draw a circular circumferential orbit in the coating booth 121, and the object 103 suspended by the hanger 105 is conveyed in the order of the coating portion 125, the coating portion 125' -heating portion 126, the thermal equilibrium portion 127, and the cooling portion 128, and predetermined processing is performed in each processing portion.

"B-2, coating material application part" (FIG. 6, FIG. 7, FIG. 14)

Outside the paint application sections 125 and 125', a gun traveling section 141 and a paint feeder 142 adjacent thereto are provided, respectively. The gun traveling part 141 is provided with a chain 143 (see fig. 14) traveling in the vertical direction and a motor 144 for traveling, and the chain 143 is provided with a gun 145 for spraying the powder coating material P. The spray gun 145 is a comb-shaped member having a plurality of nozzles in a lateral width slightly larger than the lateral width of the hanger 105, and is provided in the paint application portions 125 and 125' in a direction facing the hanger 105 being transferred. The tube connected to the spray gun 145 passes through an elongated slot formed in the peripheral wall of the paint booth 121 to be fixed to a chain 143 projecting outside the booth.

The motor 144 switches the direction of rotation to raise and lower the lance 145 in the vertical direction for a prescribed time. As the coating material shuttle 142 moves up and down, the powder coating material P is supplied to the spray gun 145 and is sprayed onto the object 103. The paint supply system or the nozzle tip of the spray gun 145 is provided with a mechanism for electrostatically charging the paint, such as a friction tube or a corona plug, so that the powder paint P sprayed from the spray gun 145 is electrostatically charged.

"B-3, heating part" (FIG. 6, FIG. 7, FIG. 11, FIG. 12)

The heating unit 126 is provided with 2 high-frequency induction coils 151 and 151'. Since the high-frequency induction coils 151 and 151 'are formed by winding a long, substantially oblong scroll on a plane, the high-frequency induction coils 151 and 151' do not have the bent portion of the high-frequency induction coil 49 as described above. The high-frequency induction coils 151 and 151' are each substantially the same size as the entire hanger 105, and are housed in 2 coil housings 152 each having a vertically long box shape in a vertical posture.

In this way, the high-frequency induction coils 151 and 151' are independent of each other in the spiral shape, but the ends are connected to each other by the copper stranded wire 153 to form an integrated circuit. The high-frequency induction coils 151 and 151' are formed of thin copper pipes so as to form water paths for cooling water to flow therethrough, and the water paths are connected by flexible hoses 154.

A slider 155 is mounted on the bottom surface of the coil housing 152, and the slider 155 is slidably engaged with a guide rail 156 provided on the bottom of the heating portion 126. Thus, the 2 high-frequency induction coils 151 and 151' are provided so as to face each other across the transfer path of the hanger 105 and to be movable so as to be able to expand and contract the distance therebetween.

And, the lower ends of the 2 coil housings 152 are fixed to the nuts 157 in a mutually reverse rotational relationship, and the nuts 157 are screwed to the 1 screw 158. The screw 158 is rotated by a stepping motor 159. Therefore, upon driving the stepping motor 159, the 2 coil housings 152 are moved toward the opposite sides to each other to expand and contract the interval between the high-frequency induction coils 151 and 151'.

"B-4, thermal equilibrium portion, Cooling portion" (FIG. 6)

The heat balance unit 127 is provided with a plurality of far infrared heaters 161 for outputting several kilowatts.

Cooling unit 128 is provided with an air blowing fan 162.

"C, coating object supply part" (FIG. 6)

In front of the coating cell 121, a workpiece supply unit 171 connected to the delivery unit 124 is provided, and the workpiece supply unit 171 has a chain 173 that is fed at a high position in a horizontally endless manner. A plurality of hanging members for hanging the hanging projections 109 of the hanger 105 are attached to the feed chain 173 at regular intervals, and the feeding chain intermittently travels with one of the hanging members coming to a position before the delivery part 124 as a stop position.

The hanger 105 for hanging the object 103 is hung on the feed chain 173 at a predetermined position of the object supply unit 171. Therefore, the hanger 105 is transported to the coating booth 121 by the feed chain 173, and is transferred to the hanger lifting rod 133 by a transfer robot not shown in the figure at a position before the transfer portion 124. After one round of travel in the coating booth 121, the hanger 105 returned to the delivery part 124 is returned to the feed chain 173 by the transfer robot, and is removed from the feed chain 173 at a predetermined position.

"D, control System" (FIG. 14)

The control system is essentially constituted by a SID-TAG system.

Fig. 14 shows control items of processing performed by the coating booth 121, in particular, a control system 181 that controls the number of times the spray gun 145 is lifted and lowered, the amount of powder paint sprayed, the positions of the high-frequency induction coils 151, 151', and the heating time of the coils.

Reference numeral 182 denotes a gun motor drive circuit for controlling the gun-travel motor 144.

183 denotes a paint valve inserted in a paint supply system connected to the spray gun 145. The paint valve 183 has an opening degree adjusting mechanism that changes the opening degree in accordance with an electrical command, and the opening degree adjusting mechanism is controlled by a paint valve control circuit 184.

A motor driving circuit for a coil for controlling the motor 159 for moving the coil housing 152 is denoted by 185, and a position sensor such as a non-contact switch is denoted by 186. The position sensor 186 detects a standby position at the movement origin of the coil housing 152, and outputs a signal when the coil housing 152 reaches the standby position indicated by the two-dot chain line shown in fig. 12.

Reference numeral 187 denotes a coil drive circuit for controlling energization of the high-frequency induction coils 151 and 151', and includes a timer 187a for controlling energization time.

Reference numeral 188 denotes a flag, and 189 denotes a data reading circuit. The item data of the substrate is written and recorded on the marking member 188 by a writing means not shown in the figure. The marker 188 is detachably attached to the aforementioned marker attaching portion 110 provided on the hanger 105.

The data recorded on the tag188 is transmitted from the antenna provided in the tag188 to the antenna of the data read circuit 189, and is read by the data read circuit 189.

Reference numeral 190 denotes a processing unit. The processing unit 190 is not limited to a narrow processing unit, and includes a memory unit such as a control data file for writing control data such as the number of times the spray gun 145 is lifted and lowered, the opening degree of the paint valve 183, the color of the paint, the amount of rotation of the stepping motor 159 for defining the distance between the coil and the object to be coated, and the time for energizing the high-frequency induction coils 151 and 151' for each type of object to be coated, and a program file for reading control data corresponding to the type read by the data reading circuit 189 from the control data file and writing a predetermined control signal to the control circuits 182, 184, 185, 187, etc.

A part of the content of the control data file is shown by table 1. TABLE 1

The powder coating apparatus 101 is constituted by the above-described members.

"E, methods of use and Effect"

Next, a method of using the powder coating apparatus 101 and an operation thereof will be described.

"E-1, Prior Art treatment"

Before coating is started, the most appropriate control data or necessary coating color data for each coated object obtained empirically is written into the control data file in association with the type of the coated object by the SID-TAG system.

While the object to be coated is being hung on the hanger 105, the most appropriate kind of object to be coated hook 108 is selected for the object to be coated, and at the same time, the number of hooks to be attached to the hook attaching bar 107 is selected. In particular, the height H (see FIG. 10) of the selected shank 108b is larger than the dimension L from the hook hole 103a to the upper end of the substrate 103. In addition, in the case where it is sufficient to support the object at 1 place, the hook of the object having the aforementioned shape can be used, and in the case where it is supported at 2 places, the handle 108b has 2 hooks of the object. When the size of the object to be coated is large, 2 hooks are attached to 1 hook attaching bar 107, and when the size is small, 3 hooks are attached.

In addition, it is empirically known that when the heating rate of the object to be coated is different depending on the position of the high-frequency induction coils 151 and 151', the high-frequency induction effect is good in a place where the heating rate is slow even for the same object to be coated, and the long hook for the object to be coated is used for the handle 108 b.

Thus, the variety or number of the hooks of the object to be coated is selected, and after the hooks are attached to the hook attaching bar 107, the object to be coated is hung on the hooks. As shown in fig. 9, the hook portion 108c of the substrate hook 108 is slightly inserted into the hook hole 103a of the substrate 103. Only the same kind of objects to be coated are hung on 1 hanger 105.

Then, the article to be coated suspended from the hanger 105 is written into the SID TAG188 and inserted into the marker mounting portion 110 of the hanger 105.

The hanger 105 in this state is hung on the feed chain 173.

"E-2, coating"

When the hanger 105 on which the object to be coated 103 is hung is transported to a predetermined position near the transfer portion 124, the data reading circuit receives the data of the marker 188. The processing unit 190 reads out control data or color data corresponding to the item data received by the data reading circuit 189 from the control data file, converts the control data or color data into a predetermined control signal, and outputs the control signal to the control circuit. The outputs are sequentially performed at a time synchronized with a signal for controlling the rotation of the main shaft 131.

Next, the hanger 105 is transferred to the hanger holding rod 133. The posture of the hanger 105 at this time is, as shown in fig. 6 and the like, performed in a posture parallel to a straight line along which the hook attaching bar 107 circumscribes the rotation locus of the hanger hanging rod 133.

In this way, the hanger 105 conveyed into the paint booth 121 is first transferred to the paint coating portion 125 and stopped at a position facing the spray gun 145. When the color of the object to be coated matches the color of the paint coating section 125, the paint coating is performed here, and when the color does not match, the object is transferred to the next paint coating section 125' to perform paint coating. The coating application was controlled as follows.

The processing unit 190 outputs a control signal to the gun traveling unit 141 or the paint shuttle 142, whereby the spray gun 145 delivers the powder paint P to the hanger 105 while moving up and down a predetermined number of times. The powder coating material P is charged with static electricity in an amount corresponding to the opening degree of the coating valve 183 controlled by the control signal, and adheres to one surface of the hanger 105 or the object 103.

When both sides are to be coated, the spray gun 145 finishes lifting a predetermined number of times, and then reverses the direction of the hanger 105, and coating of the other side is started. At this time, since the whole object 103 is located at a position lower than the hook attaching rod 107, the hook attaching rod 107 does not act as a shadow with respect to the paint sprayed onto the object 103 from the rear side, and the shank 108b of the object hook 108 is a wire rod, and the shank 108b does not affect the spraying of the paint.

"E-3, heating, etc."

The hanger 105 that has applied the powder coating material P to the coating material application section 125 or 125' in this manner is then transferred to the heating section 126. Before that, the 2 coil housings 152 come to the standby position described above, and the mutual distance is increased. Thus, the hanger 105 can smoothly enter between the 2 coil housings 152.

When the hanger 105 reaches this position, the processing unit 190 outputs a control signal to the coil motor drive circuit 185, whereby the stepping motor 159 rotates by a predetermined amount to advance the 2 coil housings 152 to predetermined positions with respect to the hanger 105, and at the same time, outputs a drive signal to the coil drive circuit 189 to energize the high-frequency induction coils 151, 151'.

The object 103 itself is heated by the induction heating of the coils 151 and 151', and the powder coating material P attached to the surface is baked and dried by the heating. Since the entire hanger 105 is made of phosphor bronze, it is not inductively heated. Therefore, the powder coating material P adhering to each portion of the hanger 105 is not baked.

After a predetermined heating time has elapsed, the energization of the high-frequency induction coils 151 and 151 'is stopped, and the coils 151 and 151' are returned to the standby position.

Next, the hanger 105 is transferred to the heat equalizing section 127, cooled by the cooling section 128 after heat equalization, returned to the delivery section 124, and placed on the feeding chain 173.

The powder coating material P adhering to the hanger 105 is blown off by a blower, not shown, provided in the thermal equalizer 127 and recovered by vacuum.

With this embodiment, the object hook 108 can be replaced or changed in position very easily, or the object hook 108 has no influence on the spraying of the coating material onto the object 103.

In addition, according to this embodiment, the heating of the high-frequency induction coil 151 is uniformly applied to all the objects 103 hung on the hanger 105, or the relative distance between the coil 151 and the objects 103 can be adjusted.

Further, according to this embodiment, the control items of the quality such as coating, baking, drying, and the like of the left and right coating materials can be automatically controlled by the hanger unit and the preset contents, and the operation efficiency is high.

While the embodiment 2 has been described above, the present invention is not limited to this embodiment, and design changes and the like without departing from the scope of the present invention are included in the present invention.

For example, in embodiment 2, the SID-TAG system is used, but not limited to this manner.

ADVANTAGEOUS EFFECTS OF INVENTION

The invention can form uniform and firm coating without mottle, and the device is miniaturized. Further improving the efficiency of the coating operation.

Claims

1. A powder coating apparatus, comprising: a hanger to which a hook for holding a substrate in a suspended state is attached to a plurality of horizontally arranged hook attaching rods, the hanger being made of a material that is not heated by high-frequency induction; a plurality of processing sections including a coating material application section for applying a powder coating material on the surface of an object to be coated by electrostatic coating and a heating section having 2 high-frequency induction coils disposed to face each other; a hanger transfer mechanism for sequentially transferring the hangers to the plurality of processing units and transferring the hangers to 2 high-frequency induction coils at the heating unit; the coating material is heated from the side of the object to be coated by heating the object to be coated by the high-frequency induction current supplied through the hanger.

2. The powder coating apparatus of claim 1, wherein the hanger is made of copper.

3. The powder coating apparatus according to claim 1, wherein a conveyor having a rotary conveyor path for rotating the object on a horizontal track is provided.

4. The powder coating apparatus according to any one of claims 1 to 3, wherein the hook to be coated has a shape having a mounting portion bent in an inverted U-shape and a shank extending from one end of the mounting portion, and a plurality of longitudinal grooves for detachably engaging with the mounting portion are formed in the hook mounting bar in a lateral direction.

5. The powder coating apparatus of claim 4, wherein the mounting portion of the hook for coating and the shank are made of a wire rod having a circular cross section, and the shank has a tip end extending to a position slightly lower than the mounting portion, and the tip end is provided with an arrow-head-shaped hook portion for hanging the object to be coated.

6. A powder coating apparatus according to any one of claims 1 to 3, wherein the 2 high-frequency induction coils are supported by coil supports which are movable in opposite directions relative to each other in the opposing direction, and wherein coil position control means for moving the coil supports is provided.

7. The powder coating apparatus according to claim 6, comprising a marker attached to the hanger and recording data corresponding to the coil position of the high-frequency heating or proxy data based on the characteristics of the object to be coated suspended by the hanger or the paint to be coated on the object to be coated, a data reading circuit for reading the data recorded on the marker, a processing unit for generating a control signal based on the data read by the data reading circuit, and a control circuit for operating the coil position control mechanism of the heating unit based on the control signal.

8. A powder coating apparatus according to any one of claims 1 to 3, comprising a marker attached to the hanger and recording data or proxy data of at least one of the number of times the spray gun is moved, the amount of powder coating material sprayed from the spray gun, and the heating time by the high-frequency induction coil based on the characteristics of the coating material or the coating material being hung from the hanger, a data reading circuit for reading the data recorded on the marker, a processing unit for generating a control signal based on the data read by the data reading circuit, and a control circuit for operating the spray gun control means of the coating material application unit and/or the coil position control means of the heating unit based on the control signal.

9. A powder coating method is characterized by comprising a coating material coating step of coating a powder coating material on the surface of an object to be coated by electrostatic coating and a heating step of having 2 high-frequency induction coils arranged to face each other; a hanger on which hooks for a substrate are mounted, the hooks being made of a material which is not heated by high-frequency induction and held in a suspended state by a plurality of horizontally arranged hook mounting bars, the substrate is sequentially transferred to a plurality of processing sections while being held, and transferred between 2 high-frequency induction coils in a heating section, and the substrate is heated by high-frequency induction current supplied from the hanger, thereby heating the coating material from the substrate side.