JP2008012403A - Spray gun - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spray gun which prevents leakage of paint from a paint nozzle when the paint is not discharged. <P>SOLUTION: The spray gun is constituted so that a guide part 40 having a projecting part 41 to be abutted on the inner peripheral surface of a paint chamber 4b is arranged all over the outer peripheral surface 16c of a needle valve 15 in the vicinity of the front end, which is arranged in the paint chamber 4b of a gun main body of the spray gun, and an outer peripheral part 41a of the projecting part 41 is slid on the inner peripheral surface of the paint chamber 4b when the needle valve 15 is moved backward and forward by a piston. Since the guide part 40 is arranged, the front end of the needle valve 15 (a tapered part 16b of a needle cap 16) can always be abutted on a predetermined position of the paint nozzle 4 and the uneven abrasion of both of the needle valve 15 and the paint nozzle 4 can be prevented. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a spray gun that turns on and off the discharge of paint by a back-and-forth movement of a needle valve disposed in a paint chamber.

A spray gun capable of atomizing paint is used for painting automobile parts and the like.
This type of spray gun has, for example, a needle valve in a paint chamber as shown in Patent Document 1.
The needle valve has a shape of a metal elongated round bar, and a front end portion of the needle valve has a tapered shape capable of coming into contact with a paint nozzle having a paint discharge port. When the needle valve comes into contact with the paint nozzle, the discharge port is closed by the tapered portion of the needle valve. The rear end portion of the needle valve is attached to the piston, and the front end portion of the needle valve comes into contact with and separates from the paint nozzle by the movement of the piston back and forth, and discharges the paint.

In the spray gun configured as described above, in order to prevent the leakage of the paint from the discharge port when the paint is not ejected, the paint nozzle and the needle valve are rubbed in advance to form a contact surface between them, and the front end of the needle valve is formed. The center and the center of the discharge port of the paint nozzle are matched.
JP 2000-117157 A

  However, when the needle valve moves back and forth, the front end of the needle valve is eccentric with respect to the paint nozzle because the needle valve is only elongated and the rear end is only fixed to the piston. was there. If the front end of the needle valve is repeatedly in contact with the paint nozzle in an eccentric manner, the needle valve or the paint nozzle may be worn out unevenly and the adhesion between the needle valve and the paint nozzle may be reduced. . In a state where the adhesion between the needle valve and the paint nozzle is lowered, there is a possibility that the paint may leak from the discharge port through the place where the adhesion is lowered when the paint is not ejected.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a spray gun that prevents as much as possible paint leakage from the discharge port when the paint is not discharged.

  The spray gun of the present invention is a paint having a gun body having a paint chamber, a paint supply passage connected to a paint supply source for supplying paint to the paint chamber, and a paint discharge port provided at the front end of the paint chamber A nozzle, a needle valve that is disposed in the paint chamber and moves in the front-rear direction so that the front end abuts and separates from the paint nozzle, and discharges the paint from the paint port, and the rear end of the needle valve A piston that is fixed to the front and back and forth by compressed air, and a guide portion that has a paint passage that is provided on the entire circumference in the vicinity of the front end portion of the needle valve, and when the needle valve moves back and forth, The outer peripheral portion is configured to slide on the inner peripheral surface of the paint chamber.

  According to the present invention, by providing the guide portion, the needle valve can be moved back and forth while maintaining the center position of the front end portion of the needle valve with respect to the paint nozzle. Accordingly, uneven wear of the needle valve and the paint nozzle can be prevented without shifting the contact position of the front end portion of the needle valve with respect to the discharge port. For this reason, the needle valve closes the discharge port of the paint nozzle without any gap, and leakage from the discharge port of the paint inside the spray gun can be prevented.

  A first embodiment in which the present invention is applied to an automatic air spray gun will be described below with reference to FIGS. When it is necessary to indicate the direction, the direction in which the paint is discharged will be described as the front.

  FIG. 5 thru | or FIG. 9 has shown the whole structure of the gun main body 1 of the air spray gun which concerns on this embodiment. The gun body 1 of the spray gun has a structure in which a body 3 is mounted on a base 2. A paint nozzle 4 and an air cap 5 which will be described later are attached to the front end portion of the body 3. Although not shown, the gun body 1 is used by being installed in a painting facility or attached to a robot arm via the base 2.

  As shown in FIGS. 6 to 9, the base 2 has a substantially rectangular block shape, and a nipple (pipe joint) 6 for supplying L-shaped piston air is provided at the bottom of the base 2. Yes. Further, on the rear surface portion, a nipple 7 for supplying pattern air and a nipple 8 for supplying atomizing air are provided so as to protrude rearward from each other. An air hose (not shown) is connected to each of the nipples 6, 7, and 8 so as to be supplied with compressed air.

  As shown in FIG. 6, a piston air supply passage 9 extending upward from the nipple 6 is formed in the base 2. The piston air supply passage 9 is connected to a piston air supply passage 10 in the body 3. As shown in FIG. 7, a pattern air supply passage 11 is formed in the base 2 so as to extend forward from the nipple 7.

  The pattern air supply passage 11 is connected to the pattern air supply passage 12 in the body 3. At the same time, an atomizing air supply passage 13 extending forward from the nipple 8 is formed in the base 2. The atomization air supply passage 13 is connected to the atomization air supply passage 14 in the body 3. FIG. 7 shows the air supply passages 11 and 13 in the base 2 in a developed state.

As shown in FIGS. 5 to 7, a cylindrical portion 3 a is provided at the front end portion of the body 3, and the paint nozzle 4 and the like are assembled to the cylindrical portion 3 a. On the rear end side of the body 3, a hole portion 3 b for assembling parts is formed, and a cylindrical paint chamber 3 c penetrating the center portion of the body 3 is formed.
A needle valve 15 for controlling the flow rate of the paint is disposed in the body 3 so as to penetrate the paint chamber 3c. The needle valve 15 includes a needle shaft 15 a and a needle cap 16. The needle valve 15 and the needle cap 16 will be described in detail later.

  As shown in FIG. 5, a nipple 17 for supplying paint and a nipple 18 for returning paint are provided on the left and right side walls of the body 3 via spacers 19, respectively. At this time, in the body 3, a paint supply passage 20 that is continuous with the nipple 17 is formed, and a paint return passage 21 that is continuous with the nipple 18 is formed. These passages 20 and 21 are configured to communicate with the paint chamber 3c. Although not shown, a paint supply hose is connected to the nipple 17, and a paint return hose is connected to the nipple 18. From an external paint supply source equipped with a paint pressure feeding pump, The paint is circulated and supplied to the paint chamber 3 c of the gun body 1.

  As shown in FIGS. 5 to 7, the paint nozzle 4 is attached to the cylindrical portion 3 a at the front end portion of the body 3 through the nozzle joint 22, and the air cap 5 is attached to the front end portion of the paint nozzle 4. It is attached via a retainer 23.

  The paint nozzle 4 has a discharge port 4a for discharging paint at the center of its front end. Further, a paint chamber 4b having a cylindrical shape extending rearward is provided behind the discharge port 4a of the paint nozzle 4 so that the center of the discharge port 4a coincides with the center of the paint chamber 4b. The paint chamber 4b is configured to continue with the same inner diameter as the paint chamber 3c. As will be described later, the discharge port 4a is closed from the inside by the front end of the needle cap 16 when the paint is not discharged, and the needle cap 16 is displaced rearward (to the right in FIG. 5 and the like). By doing so, the discharge port 4a is opened and the paint is discharged.

  Further, the paint nozzle 4 is provided with an atomizing air blowing passage 4 c that is located on the outer peripheral side of the paint chamber 4 b and opens at the front end surface of the paint nozzle 4. At this time, as shown in FIG. 7, the atomizing air blowing passage 4 c communicates with the atomizing air supply passage 14 of the body 3. Further, the air cap 5 is formed with a pattern air blowing passage 5a. As shown in FIG. 7, the pattern air blowing passage 5a communicates with the pattern air supply passage 12 of the body 3. It is like that.

  As a result, the atomizing air passes through the atomizing air supply passages 13 and 14 and the atomizing air blowing passage 4c, and is blown out from the front end of the paint nozzle 4 to make the paint discharged from the discharge port 4a into a mist. ing. On the other hand, the pattern air is blown from the front end of the air cap 5 through the pattern air supply passages 11 and 12 and the pattern air blowing passage 5a, and sprayed paint is formed in a predetermined pattern (round shape or sector shape and size). Sa). The pattern can be selected by replacing the paint nozzle 4 and the air cap 5.

  An adjusting device 24 for adjusting the displacement amount of the needle valve 15 is assembled in the hole 3b portion of the body 3, and the displacement amount of the needle valve 15 is adjusted by the adjusting device 24. 5 to 7 show a state before adjusting the displacement of the needle valve 15. Further, a seal collar 25 is provided via a screw 26 at the bottom (front end side in the figure) of the hole 3b in a state of being fitted on the outer periphery of the needle valve 15 (needle shaft 15a). The seal collar 25 prevents the paint supplied into the paint chamber 3c from leaking to the hole 3b side.

  A spring pressing member 27 is attached to the rear end of the body 3 so as to close the opening of the hole 3b. Thus, a cylinder chamber is formed in the hole 3b (between the spring pressing member 27 and the screw 26), and a piston 28 is provided in the cylinder chamber so as to be slidable in an airtight manner on the inner peripheral surface thereof. Yes. The piston 28 is fixed to the outer periphery of the needle valve 15 (needle shaft 15a) on the rear end side. A spring 29 is disposed between the piston 28 and the spring pressing member 27, and the piston 28 and the needle valve 15 are always urged forward (leftward in the figure) by the spring 29. When the paint is not discharged, the front end of the needle cap 16 closes the discharge port 4a.

As shown in FIG. 6, the front side of the piston 28 in the cylinder chamber communicates with the piston air supply passage 10 in the body 3.
The adjusting device 24 includes a ring-shaped dial member 30 fixed to the outer periphery of the spring pressing member 27, an adjusting shaft 31, a dial knob 32, and the like. The dial knob 32 has a cylindrical cap shape, is attached to the rear end portion of the adjustment shaft 31, and is provided so as to be partially fitted into the circular opening of the dial member 30. In contrast, the adjustment shaft 31 is configured to reciprocate. The adjustment shaft 31 is provided in a state where a male thread portion provided in an intermediate portion thereof is screwed to a female thread portion provided in the spring pressing member 27, and a rear end surface of the needle valve 15 is provided on a front end surface thereof. By abutting, it functions as a stopper that regulates the displacement position of the needle valve 15. A spring 33 for preventing rattling is also provided between the spring pressing member 27 and the dial knob 32.

  When the paint is discharged, the dial knob 32 of the adjusting device 24 is rotated to lower the adjusting shaft 31 backward by a predetermined amount, and a gap is formed between the front end of the adjusting shaft 31 and the rear end of the needle valve 15. The amount of needle valve 15 that can be displaced rearward is determined. In this state, when piston air is supplied into the cylinder chamber through the piston air supply passages 9 and 20, the piston 28 and the needle valve 15 are displaced rearward against the spring 29, and the discharge port 4a is opened. It is the composition to do.

Now, the needle valve 15 and the needle cap 16 will be described with reference to FIGS. FIG. 4 shows the side surface of the needle valve 15. The needle shaft 15a that forms the shaft portion of the needle valve 15 is in the shape of a long thin rod made of metal (for example, stainless steel), and male screws 15b and 15c are formed at the front end portion and the rear end portion. A needle cap 16 concentric with the needle shaft 15a is attached to the front end of the needle shaft 15a, and a piston 28 is attached to the rear end.
A rear end portion of the needle cap 16 is formed with a female screw 16a that is screwed with the needle shaft 15a. The front end portion of the needle cap 16 has a tapered portion 16b that contacts the paint nozzle 4 and opens and closes the discharge port 4a. The center of the tapered portion 16 b coincides with the center of the needle cap 16.

  As shown in FIGS. 1 to 4, a guide portion 40 is provided on the outer peripheral surface 16c of the needle cap 16 excluding the tapered portion 16b. The guide part 40 is comprised from the four convex-shaped parts 41, and it is provided so that the convex-shaped parts 41 may be located in substantially equal intervals over the perimeter of the outer peripheral surface 16c. As shown in FIG. 3, the outer peripheral portion 41 a of the convex portion 41 has a circular arc shape centering on the axial center of the needle valve 15. The radius of the arc surface is substantially equal to the radius of the paint chamber 4b, and each outer peripheral portion 41a is in contact with the inner peripheral surface of the paint chamber 4b. For this reason, the center of this circular arc surface and the center of the paint chamber 4b coincide, and the center of the front end portion of the needle valve 15 (tapered portion 16b of the needle cap 16) coincides with the center of the discharge port 4a. Therefore, the front end portion of the needle valve 15 (tapered portion 16b of the needle cap 16) is configured to always contact the position (predetermined position) where the center coincides with the paint nozzle 4.

  Further, a recess 41 b is formed between the adjacent convex portions 41. In the present embodiment, four concave portions 41b are formed by providing four convex portions 41 in the circumferential direction. A space (referred to as a paint passage 42) through which the paint passes is formed between the concave portion 41b and the paint chamber 4b, and the paint passes through the paint chambers 3c and 4b and the paint passage 42 to the discharge port 4a. The concave portion 41b has, for example, an arc shape that is recessed toward the center in the axial direction of the needle cap 16 in order to make resistance to the flow of the paint difficult to occur.

The needle cap 16 and the guide portion 40 have an integral structure, and are made of a moldable resin such as polyether ether ketone resin (PEEK).
Next, the operation of the above configuration will be described.

When the paint of the gun body 1 configured as described above is not discharged, the supply of piston air is stopped, the piston 28 is not driven, and the needle valve 15 is urged forward by the spring force of the spring 29. Further, since each convex portion 41 of the guide portion 40 provided on the needle cap 16 is in contact with the paint chamber 4b, the taper-shaped portion 16b of the needle cap 16 is in contact with a predetermined position of the paint nozzle 4 and discharges. The outlet 4a is blocked.
The supply of pattern air and atomizing air is also stopped. On the other hand, the paint is pumped from the paint supply source, supplied from the paint supply nipple 17 to the paint chambers 3c and 4b, and further discharged through the return nipple 18.

  When painting, the dial knob 32 is rotated, and the piston 28 (and thus the needle valve 15) is adjusted by supplying the piston air (compressed air) to the piston 28 portion with the adjustment shaft 31 lowered to the rear by a predetermined amount. It moves backward until it hits the shaft 31 for use. Furthermore, each convex-shaped part 41 of the guide part 40 provided in the needle valve 15 also slides on the inner peripheral surface of the paint chamber 4b. At this time, since each convex portion 41 slides on the inner peripheral surface of the paint chamber 4b, the needle valve 15 is in a state where the center position of the front end portion (needle cap 16) of the needle valve 15 with respect to the paint nozzle 4 is held. Move back and forth with.

When the tapered portion 16b of the needle cap 16 is separated from the paint nozzle 4 and the discharge port 4a is opened, the paint pumped from the paint supply source passes through the paint chambers 3c and 4b and the paint passage 42 and is discharged. It is discharged from the outlet 4a.
Simultaneously with the discharge of the paint, pattern air and atomizing air are also supplied, and the atomizing air is ejected through the atomizing air blowing passage 4c, and the pattern air is also passed through the pattern air blowing passage 5a. Thus, the paint is ejected from the paint nozzle 4 in a predetermined pattern, and the object to be coated is applied. Further, in this case, the needle valve 15 is displaced until its rear end surface comes into contact with the front end surface of the adjusting shaft 31, and the discharge port 4a is opened with an opening degree corresponding to the displacement amount. It is adjusted by 32 operations.

  When the paint is not discharged again, the supply of piston air stops, the piston air is removed from the piston 28 portion, and the needle valve 15 is urged forward by the spring force of the spring 29. As a result, the tapered portion 16b of the needle cap 16 comes into contact with a predetermined position of the paint nozzle 4 and closes the discharge port 4a. Further, the supply of the pattern air and the atomizing air is also stopped as described above, and the paint is circulated from the paint supply source.

According to the present embodiment, by providing the guide portion 40 on the outer peripheral surface 16c of the needle cap 16, the tapered portion 16b of the needle cap 16 always comes into contact with the paint nozzle 4 at a predetermined position, Uneven wear can be prevented. For this reason, when the taper-shaped part 16b of the needle cap 16 contacts the coating material nozzle 4, no gap is generated, and leakage from the discharge port 4a can be prevented when the coating material is not discharged.
By the way, in this embodiment, the needle cap 16 was made of resin. By using resin as described above, even if there is a slight dimensional error in the gap between the tapered portion 16b and the inner peripheral surface of the paint nozzle 4, the dimensional error is absorbed by the flexibility of the resin. For this reason, unlike the prior art, it is not necessary to preliminarily form the tapered portion and the inner peripheral surface of the paint nozzle by rubbing.

Further, since the needle cap 16 is made of resin, it is more likely to be worn than a conventional metal needle valve. However, since the guide part 40 is provided, the tapered part 16b of the needle cap 16 does not wear unevenly, and the whole is worn uniformly. The amount of wear of the tapered portion 16b in this way can be compensated by adjusting the dial knob 32 of the adjusting device 24 and moving the adjusting shaft 31 forward, so that the needle cap 16 is made of resin. Therefore, the paint does not easily leak from the discharge port 4a, and the number of times of durable use does not decrease as compared with a conventional metal needle valve.
In addition, in the present embodiment, the needle cap 16 can be attached to and detached from the needle shaft 15a. Therefore, when the needle cap 16 is greatly worn or deteriorated, it is only necessary to replace the needle cap 16, which is economical. Is.

FIG. 10 shows a second embodiment of the present invention, and different points from the first embodiment will be described. The same parts as those in the first embodiment are denoted by the same reference numerals.
In the second embodiment, the needle cap 16 is provided with an annular portion 43 (corresponding to a guide portion) instead of the guide portion 40 (convex portion 41). The annular portion 43 has a substantially disk shape, and the center of the annular portion 43 is configured to coincide with the centers of the needle valve 15 and the paint nozzle 4. The distance from the center of the annular portion 43 to the outer peripheral portion 43a is substantially equal to the radius of the paint chamber 3c, and the outer peripheral portion 43a of the annular portion 43 is in contact with the inner peripheral surface of the paint chamber 4b.

The annular portion 43 is provided with eight substantially cylindrical paint passages 44 extending in the axial direction. When the paint is discharged, the paint passes from the paint chambers 3c and 4b through the paint passage 44 and from the discharge port 4a. Discharge.
The annular portion 43 has an integral structure with the needle cap 16 and is made of a moldable resin such as polyether ether ketone resin (PEEK).
Even in the above configuration, the annular portion 43 provided on the outer peripheral surface 16c of the needle cap 16 is configured to slide while being aligned with the centers of the paint nozzle 4 and the discharge port 4a. The front end portion (tapered portion 16b of the needle cap 16) is always in contact with the discharge port 4a at a predetermined position, and uneven wear can be prevented.

The present invention is not limited to the above-described embodiments, and can be modified or expanded as follows.
Four convex portions 41 of the first embodiment are provided on the outer peripheral surface 16 c of the needle cap 16, but the tapered portion 16 b of the needle cap 16 abuts a predetermined position of the discharge port 4 a of the paint nozzle 4, and As long as the paint can pass without resistance, the number of convex shapes may be other than four, and the shape of the paint passage 42 may be changed accordingly.

In the annular portion 43 of the second embodiment, eight substantially cylindrical paint passages 44 are provided. The shape and number of the paint passages 44 may be any shape and number as long as the paint can pass without resistance. You can change it.
The guide portion 40 (the convex portion 41, the annular portion 43) and the needle cap 16 are integrated, but the needle cap 16 is attached to the needle shaft 15a, and the guide portion 40 (the convex portion 41, the annular portion is provided as a separate part). 43) may be attached.
The needle shaft 15a, the needle cap 16, and the convex portion 41 (annular portion 43) may be integrated.

The 1st Embodiment of this invention is shown, The expanded longitudinal cross-sectional view of a discharge outlet part Needle cap perspective view Front view of needle cap Side view of needle valve Transverse plan view of the body Longitudinal side view of gun body to show piston air supply passage Transverse plan view partially expanded to show pattern air supply passage and atomization air supply passage Side view of gun body Rear view of gun body FIG. 3 equivalent view showing the second embodiment of the present invention

Explanation of symbols

  In the drawings, 1 is a gun body, 4 is a paint nozzle, 3c and 4b are paint chambers, 4a is a discharge port, 15 is a needle valve, 15a is a needle shaft, 16 is a needle cap, 20 is a paint supply passage, 28 is a piston, Reference numeral 40 is a guide portion, 41 is a convex portion, 43 is an annular portion, 41a and 43a are outer peripheral portions, and 42 and 44 are paint passages.

Claims (5)

A gun body having a paint chamber;
A paint supply passage connected to a paint supply source for supplying paint to the paint chamber;
A paint nozzle having a paint discharge port provided at the front end of the paint chamber;
A needle valve that is disposed in the paint chamber and moves in the front-rear direction so that the front end abuts and separates from the paint nozzle, and discharges paint from the paint port;
A piston fixed to the rear end of the needle valve and moved back and forth by compressed air;
A guide part provided over the entire circumference in the vicinity of the front end part of the needle valve and having a paint passage;
The spray gun is configured such that when the needle valve moves back and forth, an outer peripheral portion of the guide portion slides on an inner peripheral surface of the paint chamber.   The spray gun according to claim 1, wherein the guide portion includes a plurality of convex portions provided on an outer periphery of the needle valve, and a paint passage is provided between the adjacent convex portions. .   The spray gun according to claim 1, wherein the guide portion includes an annular portion provided on an outer periphery of the needle valve, and a paint passage is formed in the annular portion. The needle valve is composed of a metal needle shaft, and a needle cap attached to a front end portion of the needle shaft and having a guide portion,
The spray gun according to any one of claims 1 to 3, wherein the needle cap and the guide portion are made of resin.   The spray gun according to any one of claims 1 to 4, wherein the guide portion and the needle cap have an integral structure and are detachable from the needle shaft.

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