JP4704003B2 - Electrostatic painting gun - Google Patents

Description

  The present invention relates to a gun for electrostatic coating that includes a discharge nozzle that discharges paint at the tip of a gun body, and charging means that charges the paint discharged from the discharge nozzle.

  Conventionally, an electrostatic coating gun used for electrostatic coating has a built-in high voltage generator and a pin electrode connected to the output terminal of the high voltage generator is arranged in the paint discharge passage portion of the discharge nozzle. Thus, the paint discharged from the discharge nozzle is charged to a negative high voltage and sprayed. Then, the sprayed paint particles are electrically adsorbed to the paint to which a positive voltage is applied. In general, a paint having a relatively large electric resistance is used for the electrostatic coating.

  By the way, in a coating apparatus that automatically performs a painting operation with a painting gun, a device having a color change valve capable of supplying a plurality of types of paints and cleaning solvents to the painting gun has been provided (for example, patents). Reference 1). A schematic configuration of this type of coating apparatus is shown in FIG. That is, the color change valve 3 is connected to the coating gun 1 via the paint supply pipe 2. The color change valve (manifold) 3 includes a plurality (six) of on-off valves 4 having a common outlet, and a paint supply source 5 is used for pressure feeding on the inlet side of each on-off valve 4. These are connected via a pump 6 (only one is shown). Further, a supply source 7 of a cleaning solvent (for example, thinner) is connected to one on-off valve 4 via a pump 8 for pressure feeding.

  Thus, by controlling each on-off valve 4 of the color change valve 3, it is possible to selectively supply a plurality of types of paint from the paint supply pipe 2 to the coating gun 1, and automatically perform coating. The type of paint used can be changed (so-called color change). Furthermore, the interior of the color change valve 3, the paint supply pipe 2, and the coating gun 1 can be automatically cleaned by supplying a solvent when the color is changed or at the end of the painting operation. The on-off valve 4 is driven by an air cylinder (not shown), for example.

Although not shown, a painting robot in which a painting gun is attached to the tip of the robot arm and the above-described color change valve is incorporated in the robot arm is also considered (see, for example, Patent Document 2).
JP-A-6-126223 JP-A-9-308848

  However, in the case where the color change valve 3 is provided outside the coating gun 1 as in the conventional coating apparatus (painting robot), the path of the paint from the opening / closing valve 4 of the color change valve 3 to the tip of the coating gun 1 is changed. Since the length is relatively long, it takes time for internal cleaning and color change work, and the amount of paint to be discarded and the amount of solvent to be used increase. In addition, there is a problem that the on-off valve 4 is inferior in maintainability when a defect such as clogging of dust and paint is generated.

  Accordingly, the present inventor has attempted to develop a coating gun that shortens the paint path from the on-off valve to the discharge nozzle by integrating the above-described function of the color change valve into the gun body. However, when applying such a structure in which the function of the color change valve is integrated into the gun body to an electrostatic coating gun, the solvent may have a polarity such as thinner (has conductivity). Due to many circumstances, the following problems are expected to occur.

  That is, during the electrostatic coating operation, the high voltage of the pin electrode causes the paint discharge path and the color change valve (open / close valve) to be at a high potential. When the solvent is filled, the solvent is connected to a solvent supply source (a solvent tank, a pump for pumping, etc.) through the solvent passage, and becomes a high potential. For this reason, in order to maintain the high voltage of the pin electrode, it is necessary to install a solvent supply source on an insulating stand or the like to insulate the entire solvent passage.

  However, in this state where the entire solvent passage is insulated and at a high potential, the worker's physical safety is ensured so that the worker does not touch the high potential portion, for example, the solvent supply source. It was impossible for an operator to refill the solvent tank, for example, during the painting work. Also, since solvents such as thinner are flammable, it is necessary to take measures to prevent the occurrence of sparks. Thus, improvement is required in terms of ensuring the safety associated with the high-potential passage of the solvent.

  The present invention has been made in view of the above circumstances, and an object thereof is to integrate the function of the color change valve into the gun body, and the solvent passage portion has a high potential. It is in providing the gun for electrostatic painting which can ensure sufficient safety.

The electrostatic coating gun according to the present invention includes a discharge nozzle that discharges paint at the tip of the gun body, and charging means for charging the paint discharged from the discharge nozzle. A paint supply passage for guiding the gun body to the discharge nozzle with a paint pumped from a paint supply source, a solvent supply passage for guiding a cleaning solvent pumped from a solvent supply source to the discharge nozzle, and the gun And a valve mechanism for controlling the switching and discharging of the paint and solvent provided at the front of the main body, and at least during the electrostatic coating operation, the solvent supply passage is filled with an insulating gas. Insulation gas supply means for insulating the solvent supply source from the charging means is provided, and the solvent supply passage is located at the rear of the gun body and has a check valve. The insulating gas supply means is configured to include a gas supply path having a proximal end connected to an insulating gas supply source and a distal end connected to a downstream portion of the solvent supply path immediately downstream of the check valve. The gas supply path is also provided with a check valve, and the valve mechanism is equipped with a plurality of valve units constructed by incorporating an opening / closing valve and an air cylinder for driving the opening / closing valve in the body. And the solvent unit mounting part are detachably provided, and the tip of the paint supply passage is connected to the inlet side of the on-off valve of the valve unit attached to the paint unit mounting part. A tip end portion of the solvent supply passage is connected to an inlet side of the on-off valve of the valve unit attached to the unit mounting portion for the solvent, and an outlet side of each on-off valve is connected to a base side liquid discharge passage And the base end side liquid discharge passage is extended so as to sequentially connect the unit mounting portion for the solvent and the unit mounting portion for the paint. It is characterized in that it is provided so as to be connected from the unit mounting portion to the proximal end portion of the distal end side liquid discharge passage (invention of claim 1).

  According to the gun for electrostatic painting of the present invention, the paint supplied from the paint supply source and supplied through the paint supply passage can be discharged from the discharge nozzle by the control of the valve mechanism. At this time, it is possible to charge the paint passing through the discharge nozzle by the charging means and perform an electrostatic coating operation. Also, by controlling the valve mechanism, the cleaning solvent pumped from the solvent supply source and supplied through the solvent supply passage can be supplied to the discharge nozzle, so that the inside of the paint discharge passage can be cleaned and changed in color. Work can be performed automatically. Therefore, since the color change valve function is integrated in the gun body, the paint and solvent paths are shortened to shorten the time required for internal cleaning and color change work. The amount of paint and solvent to be discarded can be reduced, and the maintainability of the on-off valve portion can be improved.

During the electrostatic coating operation, the insulating gas supply means fills the solvent supply passage with the insulating gas, so that the conduction state with the charging means is interrupted and the solvent supply source is insulated from the charging means. Therefore, in the state where the high potential of the charging means is secured, the solvent passage and the solvent supply source can be grounded in the upstream portion from the insulating portion of the solvent supply passage, so that the ground potential can be obtained. Safety can be ensured and the occurrence of sparks can be prevented.
Further, when the insulating gas is supplied from the gas supply passage to the solvent supply passage, the check valve in the solvent supply passage effectively prevents the solvent from being supplied to the downstream portion of the check valve. Conversely, when the solvent is supplied to the solvent supply passage, it is possible to prevent the insulating gas from being supplied by the check valve provided in the gas supply passage. In addition, safety can be ensured if both check valves are electrically connected to the grounding portion.
In addition, since the on-off valve and air cylinder are unitized as a valve unit, for example, when trouble such as a defective on-off valve occurs, maintenance can be easily performed by removing and replacing the entire valve unit. become.

  In the present invention, the above-mentioned valve mechanism is provided on the front side of the gun body, a grounding part is provided on the rear side of the gun body, the inner wall is made of an insulating material, and the solvent is provided extending backward from the valve mechanism part. The supply passage may be configured to electrically connect the inside of the supply passage to the grounding portion at the rear portion of the gun body (invention of claim 2). According to this, the insulation distance between the high potential portion by the charging means and the grounding portion can be secured, and the ground potential can be set on the rear side of the gun body, so that safety is further improved. be able to.

  According to the electrostatic coating gun of the present invention, the function of the color change valve is integrally incorporated in the gun body, and at least during the electrostatic coating operation, the insulating gas supply means is provided in the solvent supply passage. Insulation from the charging means of the solvent supply source by filling the gas with an insulating gas makes it possible to ensure sufficient safety associated with the solvent passage portion having a high potential. There is an effect.

  Hereinafter, an embodiment in which the present invention is applied to an automatic gun for electrostatic coating will be described with reference to FIGS.

  First, with reference to FIGS. 2-7, the whole structure of the coating gun which concerns on a present Example is described. As shown in FIGS. 2 and 3, the gun body 11 of the painting gun as a whole has a cylindrical shape in which the tip side (left side in the figure) is slightly depressed, and more specifically, a manifold located on the tip side. 12 and a rear cover 13 made of an insulating material located on the rear side are joined by a cylindrical shroud 14 made of an insulating material. A valve mechanism is incorporated in the manifold 12 as will be described later.

  Further, a nozzle portion 15 to be described later for discharging paint in a predetermined shape is attached to the tip of the gun body 11 (the manifold 12) so as to be replaceable (detachable). Further, a metal base block 16 is provided on the rear surface side of the rear cover 13. The base block 16 extends downward from the lower end portion and has a bracket 16a integrally therewith. Although not shown, the gun body 11 is attached to the end of the arm of the painting robot or fixedly attached to the painting facility by the bracket 16a. At this time, the base block 16 (bracket 16a) is grounded, and has a function as a grounding portion according to the present invention.

  As shown in FIG. 7, a power pack (cascade) 17 is disposed in the gun body 11 so as to be located at the center in the axial direction and extend back and forth between the manifold 12 and the rear cover 13. ing. As is well known, the power pack 17 is configured by molding a high voltage generating circuit for generating a DC high voltage with an insulating material. As shown in FIGS. 2 and 3, the power pack 17 is connected to a high-frequency voltage via a connection cable 19 connected to a connector portion 18 provided at the center of the rear end surface (base block 16) of the gun body 11. Is supplied, and the generated DC high voltage (negative high voltage) is output to the output terminal 20 at the tip. The output terminal 20 is electrically connected to a nozzle sheet 21 provided at the center of the tip of the manifold 12, and the nozzle sheet 21 is further connected to a pin electrode 22. The power pack 17 and the pin electrode 22 make up a charging means for charging the paint.

  The nozzle portion 15 includes a discharge nozzle 24 attached to the distal end portion of the manifold 12 via a nozzle joint 23, an air cap 26 attached to the distal end portion of the discharge nozzle 24 via a retainer 25, and the like. Has been. The discharge nozzle 24 has a paint discharge passage 24a that extends in the front-rear direction and discharges paint from the tip, and the paint discharge passage 24a is provided with a tip center portion of the manifold 12 extending in the axial direction. The side liquid discharge passage 27 (see FIG. 2) is connected (communication) via the nozzle sheet 21. At this time, the pin electrode 22 is disposed so as to extend in the center of the paint discharge passage 24a, so that the discharged paint is charged.

  The air cap 26 is provided with an atomizing air outlet 26a that is located immediately outside the tip of the paint discharge passage 24a of the discharge nozzle 24 and that atomizes the discharged paint. A pattern air outlet 26b is provided on the outer peripheral portion for making the cross-sectional shape of the sprayed paint into a predetermined pattern (for example, a flat oval). In the nozzle portion 15, an atomizing air outlet passage 28 communicating with the atomizing air outlet 26a and a pattern air outlet passage 29 communicating with the pattern air outlet 26b are provided. ing.

  At this time, as shown in FIG. 2, the atomizing air outlet passage 28 communicates with the atomizing air passage 30 formed in the manifold 12, and the atomizing air passage 30 is The gun body 11 is connected to a hose connection port 32 provided in the base block 16 via an atomizing air supply pipe 31 extending in the front-rear direction. As shown in FIG. 3, the pattern air outlet passage 29 communicates with the pattern air passage 33 formed in the manifold 12, and the pattern air passage 33 passes through the inside of the gun body 11. A pattern air supply pipe 34 extending in the front-rear direction is connected to a hose connection port 35 provided in the base block 16. A hose is connected to each of the hose connection ports 32 and 35 so that compressed air is supplied from an air supply source (not shown). The atomizing air supply pipe 31 and the pattern air supply pipe 34 are made of an insulating material.

  The gun body 11 is provided with a valve mechanism for controlling the discharge of liquid toward the discharge nozzle 24 (liquid discharge passage) in the front manifold 12 and is pumped from a liquid supply source. A plurality of liquid passages for guiding the liquid (paint and cleaning solvent) to the valve mechanism are provided. The valve mechanism is configured by detachably providing a plurality of valve units 37 each having an on-off valve 36 for controlling liquid discharge in the manifold 12.

  In the present embodiment, a plurality of (5 in this case) liquid passages are provided, and the same number (5 in this case) of valve units 37 are provided. At this time, four liquid passages out of the five liquid passages are used as paint supply passages, and the remaining one liquid passage is used as a solvent supply passage for supplying a cleaning solvent (for example, thinner). Further, in this embodiment, the gun body 11 has four return passages for returning the liquid (paint) supplied to the valve unit 37 to the liquid supply source side corresponding to the four paint supply passages. Provided.

  First, as shown in FIG. 4, on the rear side of the base block 16, five liquid supply hose connection ports 38 to which a hose for supplying liquid (paint and solvent) is connected, and for returning the liquid (paint) The four return hose connection ports 39 to which the other hoses are connected are provided alternately in a circle. Further, five driving air hose connection ports 40 corresponding to the liquid supply hose connection ports 38 are also provided on the outer peripheral side thereof. In addition, when it is necessary to distinguish the five liquid supply hose connection ports 38, they are referred to as first to fifth liquid supply hose connection ports 38 in order from the lower left side in the clockwise direction in FIG. 38, (A) to (E) are attached. The return hose connection port 39 and the drive air hose connection port 40 also conform to this.

  At this time, although not shown in detail, in the present embodiment, the first to fourth liquid supply hose connection ports 38 (A) to 38 (D) include a paint tank, a pressure feed pump, a paint mixing device, and the like. The supply source is connected via a hose, and the paint as a liquid is pumped. The fifth liquid supply hose connection port 38 (E) is connected to a solvent supply source including a tank of a solvent (such as thinner) and a pressure feed pump via a hose. The solvent is pumped.

  Also, although not shown, the first to fourth return hose connection ports 39 (A) to 39 (D) have paints for returning the paints to the respective paint supply sources as necessary. A return hose is connected. The driving air hose connection ports 40 (A) to 40 (E) are connected to hoses for supplying compressed air for driving an air cylinder, which will be described later, from an air supply source (not shown).

  Further, in the present embodiment, the fifth liquid supply hose connection port 38 (E) is connected to a fifth liquid supply pipe 45 (E) as a solvent supply passage to be described later, A replacement air hose connection port 41 is provided in the vicinity of the liquid supply hose connection port 38 (E). The replacement air hose connection port 41 is connected to a hose for supplying replacement air, which is an insulating gas, from an air supply source such as a compressor (not shown). At this time, as shown in FIG. 8, the replacement air hose connection port 41 is connected to the base end side portion of the fifth liquid supply pipe 45 (E) by the gas supply path 42 provided in the base block 16. It is connected. Thus, the solvent in the solvent supply passage can be replaced with air as an insulating gas, and thus an insulating gas supply means is configured.

  The fifth liquid supply hose connection port 38 (E) and the replacement air hose connection port 41 (gas supply path 42) are provided with check valves 43 and 44 for preventing backflow, respectively. As a result, when the solvent is supplied (pumped) to the fifth liquid supply pipe 45 (E), the check valve 44 is closed, and the fifth liquid supply pipe 45 (E) is connected via the gas supply path 42. When the compressed air is supplied to the inside, the check valve 43 is closed, so that the solvent and the compressed air can be simultaneously supplied into the fifth liquid supply pipe 45 (E). Not to be. These check valves 43 and 44 are both electrically connected to the base block 16 (grounding portion).

  As shown in FIGS. 2, 3, and 7, the gun body 11 extends in the front-rear direction so as to be spanned between the base block 16 and the manifold 12, and includes first to fifth five pieces. Liquid supply pipes 45 (A) to 45 (E), first to fourth four liquid return pipes 46 (A) to 46 (D) (shown only in FIG. 7), and first to first Fifth five driving air supply pipes 47 (A) to 47 (E) (see FIGS. 6 and 7) are provided.

  As shown in FIG. 6, the base end portions of the first to fifth liquid supply pipes 45 (A) to 45 (E) are the first to fifth liquid supply hose connection ports 38 (A), respectively. To 38 (E), and the tip ends thereof are connected to first to fifth liquid supply paths 48 (A) to 48 (E) provided in the manifold 12, respectively. Thus, four paint supply passages are configured from the first to fourth liquid supply pipes 45 (A) to 45 (D) and the first to fourth liquid supply paths 48 (A) to 48 (D). In addition, a solvent supply passage is constituted by the fifth liquid supply pipe 45 (E) and the fifth liquid supply passage 48 (E).

  Further, the proximal end portions of the first to fourth liquid return pipes 46 (A) to 46 (D) are respectively connected to the first to fourth return hose connection ports 39 (A) to 39 (D). , And tip portions thereof are connected to first to fourth liquid return passages 49 (A) to 49 (D) provided in the manifold 12, respectively. Accordingly, the liquid return pipe 46, the liquid return path 49 and the like constitute a return path. The base end portions of the first to fifth driving air supply pipes 47 (A) to 47 (E) are respectively connected to the first to fifth driving air hose connection ports 40 (A) to 40 (E). ), And the tip portion is connected to each unit mounting portion (air cylinder of the valve unit 37) described later provided on the manifold 12. Each of the liquid supply pipes 45 and the liquid return pipes 46 is made of an insulating material. Among them, the first to fourth liquid supply pipes 45 (A) to 45 (D) and the first to fourth liquid return pipes 46 ( A) to 46 (D) are provided in an insulated state with respect to the base block 16.

  The manifold 12 is provided with the liquid supply path 48 and the liquid return path 49 described above, and is provided with a unit mounting portion 50 to which each of the five valve units 37 is mounted. Hereinafter, the unit mounting portion 50 and the valve unit 37 will be described in detail. In addition, when it is necessary to distinguish the five unit mounting portions 50 as well, the first to the first in the clockwise direction from the lower left side in FIG. 5 according to the liquid supply hose connection port 38 and the like. 5, the unit mounting portion 50 is denoted by (A) to (E).

  As shown in FIGS. 2, 3, and 5, each unit mounting portion 50 is configured by providing a circular hole extending radially from the outer peripheral surface of the manifold 12 toward the center. As shown in FIG. 5, the five unit mounting portions 50 are arranged substantially evenly with respect to the axial center, that is, arranged in a circle. A female thread portion 50a for mounting the valve unit 37 is formed on the inner peripheral surface of each unit mounting portion 50 on the opening end side (the outer peripheral side portion of the manifold 12). As shown in FIGS. 2, 3, and 9, an insertion hole 50 b (see FIG. 9) into which the positioning pin 51 is inserted is provided in the end portion of the bottom of each unit mounting portion 50. .

  Further, at the bottom of the hole of each unit mounting portion 50, as shown with reference numeral only in FIG. 9, a liquid discharge port 52 is opened at the center of the circular bottom surface, The liquid introduction port 53 is opened at the position. Further, the first to fourth unit mounting portions 50 (A) to (D) return the liquid to a position at an angle of 90 degrees with respect to the center of the bottom (the liquid discharge port 52) with respect to the liquid inlet 53. The mouth 54 is open. The fifth unit mounting portion 50 (E) is configured such that the liquid return port 54 does not exist.

  As shown in FIGS. 2, 3, and 5, each of the liquid discharge ports 52 is connected to the proximal end portion of the distal end side liquid discharge passage 27 via the proximal end side liquid discharge passage 55. Yes. At this time, as shown in FIG. 5, the proximal-side liquid discharge passage 55 includes the fifth unit mounting portion 50 (E), the fourth unit mounting portion 50 (D), and the third unit mounting portion 50 (C ), The second unit mounting portion 50 (B), the first unit mounting portion 50 (A), and the liquid discharge ports 52 of the first unit mounting portion 50 (A). It is provided so as to be connected from the outlet 52 to the proximal end portion of the distal end side liquid discharge passage 27.

  In addition, as shown in FIGS. 2, 3, and 5, the liquid introduction ports 53 are connected to the liquid supply paths 48. At this time, as shown in FIG. 6, each of the liquid supply paths 48 extends from the portion where the tip of the liquid supply pipe 45 is connected to the inside of the manifold 12 toward the radially inner periphery, and then axially ( It bends so as to extend toward the front side, and further extends so as to bend toward the outer peripheral side in the radial direction to reach each liquid inlet 53. Although not shown in detail, each liquid return port 54 is connected to each liquid return passage 49 in the same manner.

  On the other hand, the valve unit 37 is configured as follows. That is, FIG. 1 shows a vertical cross-sectional configuration of the valve knit 37, and the valve unit 37 has a cylindrical shape that fits almost closely into the unit mounting portion 50 as a whole. The valve unit 37 is configured by incorporating the opening / closing valve 36 and an air cylinder 57 for driving the opening / closing valve 36 into a body 56, and an inlet 58 for receiving liquid from the liquid supply path 48 and An outlet 59 is provided for allowing the liquid that has passed through the on-off valve 36 to flow out to the proximal-end-side liquid discharge passage 55.

  The body 56 has a cylindrical shape having an insertion hole 56a through which the rod 60a of the piston 60 constituting the air cylinder 57 is inserted, and a housing 61 is attached to the tip of the body 56 by screwing. The on-off valve 36 includes a valve seat (seat) 62 attached to the center of the front end of the housing 61, and a valve body 63 attached to the front end of the rod 60a of the piston 60.

  At this time, the housing 61 is provided with the inflow port 58 on the front end surface (the surface facing the left side in FIG. 1), and the inflow chamber 64 continuous from the inflow port 58 between the body 56 and the housing 61. Is formed. The outlet 59 is provided at the center of the valve seat 62. Further, as shown only in FIG. 5, a return port 70 connected to the inflow chamber 64 is formed on the front end surface of the housing 61 at a position 90 degrees from the inflow port 58 around the outflow port 59. Yes. Therefore, the inflow port 58, the outflow port 59, and the return port 70 are arranged on one surface (tip surface) of the valve unit 37.

  A groove 61 a into which the positioning pin 51 is fitted is formed on the outer peripheral surface on the front end side of the housing 61. In this description, the valve unit 37 has a return port 70 (a type that can be circulated), but in a non-circulation type, the housing 61 is provided with a return port 70. Not supposed to be. Further, O-rings 68 and 69 as seal members for sealing the periphery of the inflow port 58, the periphery of the outflow port 59, and the periphery of the return port 70 (not shown) are provided on the front end surface portion of the housing 61. It can be installed.

  On the other hand, a cylindrical cylinder portion 56b constituting the air cylinder 57 is integrally provided on the base end side of the body 56, and compressed air from the driving air supply pipe 47 is provided in the cylinder portion 56b. A plurality of air introduction holes 56c for introducing air are formed. Further, an attachment cap 65 is rotatably attached to the base end portion of the body 56 (cylinder portion 56b) and is prevented from being pulled out in the front-rear direction (left-right direction in the figure). On the outer peripheral portion of the cap 65, a male screw portion 65a that is screwed into the female screw portion 50a of the unit mounting portion 50 is formed. On the rear end surface portion of the cap 65, for example, two for inserting a tool. Hole 65b is formed.

  The piston 60 has an outer peripheral surface provided on the inner peripheral surface of the cylinder portion 56b so as to be slidable in the axial direction. At this time, the air introduction is performed between the bottom surface portion on the distal end side of the cylinder portion 56b and the piston 60. An air introduction chamber 66 communicating with the port 56c is formed. A spring 67 is disposed between the piston 60 and the cap 65. Accordingly, an air cylinder 57 is configured by the cylinder portion 56b, the piston 60, the air introduction chamber 66, the spring 67, and the like. Although detailed description (and reference numerals) is omitted, sealing members such as O-rings and U-packings are also provided around the air inlet 56c on the outer periphery of the valve knit 37 and inside the valve unit 37. Is arranged.

  Accordingly, in a normal state, that is, in a state where compressed air is not introduced into the air introduction chamber 66, the piston 60 is at the position shown in FIG. The outlet 59 is closed in close contact with the valve seat 62 (the on-off valve 36 is closed). When compressed air is introduced into the air introduction chamber 66, the piston 60 is displaced to the right in the figure against the spring force of the spring 67, and the valve body 63 is separated from the valve seat 62 to be separated from the outlet 59. Is opened (the on-off valve 36 is opened). When the on-off valve 36 is opened, the liquid (paint and cleaning liquid) that has flowed into the inflow chamber 64 flows out (discharges) from the outflow port 59.

  At this time, in the valve unit 37 of the type having the return port 70 as described above, the liquid supplied (pressure-fed) into the inflow chamber 64 through the inflow port 58 when the on-off valve 36 is closed remains as it is. It is discharged from the return port 70 (circulated). As described above, the valve unit 37 of the type that does not have the return port 70 has no return port 70 in the housing 61 (the return port 70 is in a closed form), and other parts. That is, the outer shape and the like are not different from those of the valve unit 37 having the return port 70. When it is necessary to distinguish between them, the type having the return port 70 is referred to as a valve unit 37 (R), and the type having no return port 70 is referred to as the valve unit 37 (S). Called.

  As shown in FIG. 5, the valve unit 37 configured as described above is detachably attached to each unit mounting portion 50 of the gun body 11, thereby configuring a valve mechanism. In this embodiment, valve units 37 (R) of a type having a return port 70 are respectively attached to the first to fourth unit mounting portions 50 (A) to (D) for paint. On the other hand, a valve unit 37 (S) of a type that does not have the return port 70 is attached to the fifth unit mounting portion 50 (E) for the solvent.

  2 and 3, the valve unit 37 is inserted into the unit mounting portion 50 from the outer peripheral side of the manifold 12, and the positioning pin 51 inserted into the insertion hole 50 b is attached to the housing 61. The valve unit 37 is aligned in the circumferential direction by fitting the formed groove 61a. In this state, by inserting a tool into the hole 65b in the rear end surface portion of the cap 65 and rotating it, the male screw portion 65a on the outer peripheral portion of the cap 65 is screwed (tightened) to the female screw portion 50a of the unit mounting portion 50. Thus, the valve unit 37 is mounted on the unit mounting portion 50. The valve unit 37 can be removed by the reverse procedure to the above.

  2, 3, and 5, the outlet 59 of each valve unit 37 is connected to the liquid discharge port 52 of each unit mounting portion 50 and the inlet 58 of each valve unit 37. Is connected to the liquid inlet 53. In the first to fourth unit mounting portions 50 (A) to (D), the return port 70 of each valve unit 37 is connected to the liquid return port 54. Further, the distal end portion of each driving air supply pipe 47 is connected to the air introduction hole 56 c of each valve unit 37 so that compressed air can be supplied to the air introduction chamber 66.

  Although not shown, in the above-described coating gun, high-frequency voltage is supplied to the power pack 17, atomizing air is supplied from the atomizing air supply source, and pattern air is supplied from the pattern air supply source. Supply, supply of each paint from four paint supply sources (pressure feeding), supply of solvent from the solvent supply source, replacement into the fifth liquid supply pipe 45 (E) through the gas supply path 42 The supply of air, the supply of driving air to each valve unit 37 (each air cylinder 57) of the valve mechanism, and the like are controlled according to a preset control program by a control device including a microcomputer. It has become so.

  At this time, as will be described in the following description of the operation, the control device, due to its software configuration (execution of the control program), causes the liquid discharge passages 27 and 55 and the discharge nozzle at the time of paint color change or at the end of the painting operation. In executing the cleaning process for cleaning the inside of the liquid 24, the pressure feed pump of the solvent supply source is driven to supply the solvent from the fifth liquid supply pipe 45 (E), and the fifth unit mounting portion 50 (E The open / close valve 36 of the valve unit 37 (S) attached to () is opened.

  In other steps, the pressure supply pump of the solvent supply source is stopped to stop the supply of the solvent to the fifth liquid supply pipe 45 (E), and the replacement gas is replaced with an insulating gas through the gas supply path 42. Air is supplied, and the fifth liquid supply pipe 45 (E) and the fifth liquid supply path 48 (E) are filled with air. Therefore, at least during the electrostatic coating operation, the fifth liquid supply pipe 45 (E) and the fifth liquid supply path 48 (E) are filled with air, and the solvent supply source and the valve unit 37 (S) portion. Is designed to be insulated from each other.

  Next, the operation of the above configuration will be described. As described above, the first to fourth liquid supply hose connection ports 38 (A) to 38 (D) of the base block 16 are connected to paint supply sources for supplying different types of paints, respectively. A solvent supply source is connected to the liquid supply hose connection port 38 (E). A replacement air supply source is connected to the replacement air hose connection port 41. In the present embodiment, the four types of paints to be supplied are of a type that is always used while being circulated. The solvent (thinner) has a relatively high conductivity, and all the paints have a relatively low conductivity (high resistance).

  At this time, in the case of using a paint that is simply used up (non-circulating type) such as a two-component curable paint, the valve unit 37 (R) corresponding to the connection port 38 to which the paint is connected is used. The valve unit 37 (S) may be replaced with a type that does not have the return port 70. Moreover, it is not always necessary to use all of the first to fourth liquid supply hose connection ports 38 (A) to 38 (D). Only the first to third liquid supply hose connection ports 38 (A) to 38 (C) may be used. Furthermore, some paints have a relatively high conductivity. In this case, a paint supply source (a paint tank and a pressure pump) is arranged on an insulating base.

  The paint supplied (pressure fed) from the paint supply source passes from the liquid supply hose connection port 38 through the liquid supply pipe 45, further through the liquid supply path 48 of the manifold 12 to the liquid inlet 53, and the valve unit 37 (R). From the inlet 58 to the inflow chamber 64. Here, in a state where the on-off valve 36 of the valve unit 37 (R) is closed, the paint flowing into the inflow chamber 64 passes through the liquid return passage 49 from the return port 70 through the liquid return port 54, and further. The liquid return pipe 46 and the return hose connection port 39 are returned to the paint supply source through the hose. Thereby, the circulation of the paint is performed, and the precipitation and hardening of the pigment in the paint are prevented in advance.

In this state, when the air cylinder 57 is driven by the supply of driving air and the on-off valve 36 of the corresponding valve unit 37 (R) is opened, the paint flowing into the inflow chamber 64 is discharged from the outflow port 59. A state in which the liquid is discharged, passes through the liquid discharge port 52 from the base end side liquid discharge passage 55 and the tip end side liquid discharge passage 27 in order, reaches the paint discharge passage 24a of the discharge nozzle 24, and is charged to a negative high voltage by the pin electrode 22 The spray nozzle 24 sprays a positive voltage toward the coated object, and electrostatic coating is performed. At this time, the paint is atomized by the air blown from the atomizing air outlet 26a of the air cap 26, and a predetermined spray pattern of the paint is formed by the air blown from the pattern air outlet 26b. Is done. When the on-off valve 36 is closed, the spraying of paint is stopped. At the time of this painting operation, air is supplied into the fifth liquid supply pipe 45 (E) and the fifth liquid supply path 48 (E) (the internal solvent is replaced with air). ing.

  On the other hand, when changing the type of paint used for painting (color change), a cleaning process for cleaning the inside of the liquid discharge passages 55 and 27 and the discharge nozzle 24 is executed. In this cleaning process, the power supply to the power pack is stopped, and the supply of paint and the supply of atomization and pattern air are stopped. In this state, the pressure supply pump of the solvent supply source is driven to supply the solvent (thinner) to the fifth liquid supply pipe 45 (E), and further to the fifth unit mounting portion 50 (E). When the on-off valve 36 of the attached valve unit 37 (S) is opened, the solvent passes through the fifth liquid supply path 48 (E) of the manifold 12 as shown in FIG. It flows into the inflow chamber 64 from the inlet 58 of (S).

  Then, the solvent that has flowed into the inflow chamber 64 is discharged from the outflow port 59, and sequentially passes from the liquid discharge port 52 through the proximal end side liquid discharge passage 55 and the distal end side liquid discharge passage 27 to the paint discharge passage 24 a of the discharge nozzle 24. Then, the ink is discharged from the discharge nozzle 24. At this time, while the air filled in the solvent supply passage is pushed out and discharged, the paint remaining in the liquid discharge passages 55 and 27 and the discharge nozzle 24 is also discharged, and the paint passage is cleaned. The Further, as shown in FIG. 5, since the solvent is discharged to the most upstream side of the base end side liquid discharge passage 55, the entire base end side liquid discharge passage 55 can be cleaned.

When this cleaning process is completed, the solvent pump is stopped by stopping the on-off valve 36 of the valve unit 37 (S) and the supply of the solvent is stopped. Then, as shown in FIG. The supply source is driven and compressed air is supplied to the fifth liquid supply pipe 45 (E) through the gas supply path 42. At this results in so that the solvent remained is discharged, the discharge of the solvent is completed, the on-off valve 36 of the valve unit 37 (S) is closed, it is also stopped air supply sources for replacement . As a result, the fifth liquid supply pipe 45 (E) and the fifth liquid supply path 48 (E) are filled with air. Thereafter, the electrostatic coating operation using the following type of paint is performed as described above. Is executed in the same way as

  Therefore, at the time of the electrostatic coating operation described above, the tip end portion (nozzle portion 15 portion) of the gun body 11 is at a high potential, and the valve unit 37 portion is passed through the paint in the liquid discharge passages 55 and 27. Is also at a high potential. Accordingly, if a highly conductive solvent is filled from the solvent supply source to the fifth liquid supply pipe 45 (E) and the fifth liquid supply path 48 (E) during this electrostatic coating, In order to maintain the high voltage at the tip of the main body 11, it is necessary to insulate the entire passage from the solvent supply source. However, in this case, it is necessary to ensure the safety of the worker's body so that the worker does not touch a high potential portion such as a solvent supply source. It is impossible to replenish the tank with a solvent, and the solvent such as thinner is flammable, so it is necessary to take measures to prevent the occurrence of sparks.

  In contrast, in the present embodiment, during the electrostatic coating operation, the inside of the fifth liquid supply pipe 45 (E) and the fifth liquid supply path 48 (E) is replaced with air, and the check valve 43 Since the valve unit 37 (S) is insulated, even if the check valve 43 is electrically connected to the base block 16 as a grounding portion and the solvent supply source to the check valve 43 are grounded, the gun body 11 It is possible to maintain a high voltage at the tip of the. At this time, since the base block 16 is provided at the rear portion of the gun body 11, a sufficient insulation distance from the high potential portion at the tip of the gun body 11 can be ensured.

  Therefore, the solvent tank can be used while being grounded, the safety of the worker's body can be ensured, the solvent tank can be replenished with the solvent, and the flammable solvent can be used. Safety is also secured in terms of preventing ignition. In addition, as described above, in the case of using conductive paint, it is necessary to arrange the paint supply source (paint tank and pressure pump) on the insulating frame. Since the flammability is low, there is not much inconvenience in terms of safety.

  During the above-described painting operation, troubles such as dust and paint blockages may occur in the on-off valve 36 of the valve unit 37, for example. When such a trouble occurs, in the configuration of the present embodiment, the apparatus is stopped, the defective valve unit 37 is removed from the unit mounting portion 50, and a new valve unit 37 is attached to the unit mounting portion 50. It only has to be attached (replaced). Thus, maintenance work can be easily performed in a short time.

  As described above, according to the present embodiment, during the electrostatic painting operation, the fifth liquid supply pipe 45 (E) and the fifth liquid supply path 48 (E) are filled with air. With the high potential of the discharge nozzle 24 portion at the tip of the gun body 11 secured, the solvent passage and the solvent supply source upstream from the insulating portion can be grounded to achieve ground potential. As a result, it is possible to ensure the safety of the worker's body and to prevent the occurrence of sparks.

  And since the structure of the color change valve is integrated in the gun body 11, the path of the paint and solvent is shortened to shorten the time required for internal cleaning and color change work. In addition, it is possible to reduce the amount of paint and solvent used, and to improve the maintainability of the on-off valve 36 portion. In particular, in this embodiment, the on-off valve 36 and the air cylinder 57 are unitized as a valve unit 37. Therefore, when a trouble such as a failure of the on-off valve 36 occurs, the entire valve unit 37 can be removed and easily replaced. Thus, maintenance can be easily performed.

  The present invention is not limited to the above-described embodiment. For example, various modifications can be made to the configuration of the nozzle portion 15 and the specific configuration of the valve mechanism. In the above-described embodiment, five valve units are provided. Although it is configured to be provided, three, four, or six or more may be provided. In addition, the present invention can be implemented with appropriate modifications within a range not departing from the gist.

1 shows an embodiment of the present invention, and is an enlarged vertical side view of a valve unit. Longitudinal side view of gun body (cross-sectional view taken along line D-E in FIG. 4) Cross-sectional plan view of gun body (cross-sectional view along line FG in FIG. 4) Rear view of gun body Vertical rear view along line AA in FIG. Longitudinal rear view along line BB in FIG. Longitudinal rear view along line CC in FIG. FIG. 4 is an enlarged longitudinal side view taken along line II of FIG. Enlarged bottom view along line HH in FIG. The figure which shows a conventional example and shows the whole composition of a painting device roughly

Explanation of symbols

In the drawing, 11 is a gun body, 12 is a manifold, 15 is a nozzle part, 16 is a base block (grounding part), 17 is a power pack (charging means), 22 is a pin electrode (charging means), 24 is a discharge nozzle, 24a Is a coating material discharge passage, 27 is a front end side liquid discharge passage, 36 is an on-off valve, 37 is a valve unit, 41 is a replacement air hose connection port, 42 is a gas supply passage, 43 and 44 are check valves, and 45 is a liquid supply pipe , 46 is a liquid return pipe, 48 is a liquid supply path, 49 is a liquid return path, 50 is a unit mounting portion, 55 is a proximal end side liquid discharge path, 56 is a body, 57 is an air cylinder, 58 is an inlet, 59 is An outflow port, 60 is a piston, 64 is an inflow chamber, and 70 is a return port.

Claims (2)

An electrostatic coating gun comprising a discharge nozzle for discharging paint at the tip of the gun body, and a charging means for charging the paint discharged from the discharge nozzle,
The gun body has a paint supply passage for introducing the coating material is pumped from the paint supply source to the discharge nozzle, the solvent supply passage for introducing a solvent for cleaning which is pumped from the solvent supply source to the discharge nozzle, the gun body And a valve mechanism for controlling the switching and discharging of the paint and solvent provided at the front, and
At least during the electrostatic coating operation, an insulating gas supply means is provided for insulation from the charging means of the solvent supply source by filling the solvent supply passage with an insulating gas,
The solvent supply passage has a check valve located at the rear of the gun body;
The insulating gas supply means includes a gas supply path having a proximal end connected to an insulating gas supply source and a distal end connected to a portion immediately downstream of the check valve in the solvent supply path,
The gas supply path is also provided with a check valve ,
The valve mechanism includes a plurality of valve units configured to incorporate an on-off valve and an air cylinder that drives the on-off valve in a body, which are detachably attached to a unit mounting portion for paint and a unit mounting portion for solvent. Configured
The tip of the paint supply passage is connected to the inlet side of the on-off valve of the valve unit attached to the paint unit mounting part,
The tip of the solvent supply passage is connected to the inlet side of the on-off valve of the valve unit attached to the unit mounting portion for the solvent,
The outlet side of each on-off valve is connected to the discharge nozzle via a base end side liquid discharge passage and a tip end side liquid discharge passage,
The base end side liquid discharge passage extends so as to sequentially connect the unit mounting portion for the solvent and the unit mounting portion for the paint, and extends from the unit mounting portion for the paint to the base end portion of the tip side liquid discharge passage. An electrostatic coating gun characterized by being connected . The valve mechanism is provided on the front side of the gun body, and a grounding portion is provided on the rear side of the gun body.
The solvent supply passage is provided with an inner wall made of an insulating material and extending rearward from the valve mechanism portion, and the interior is electrically connected to the grounding portion at the rear of the gun body. The gun for electrostatic coating according to claim 1.

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