JPH0454501B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a hand gun for coating by manually discharging sealant, paint, etc. pressurized to a predetermined pressure from a discharge port.

Conventional techniques and problems to be solved by the invention Conventionally, in order to apply a liquid by discharging a liquid pressurized to a predetermined pressure from a discharge port, such as with a hand gun for applying sealant or an airless spray gun for painting, Dispensing guns are used that use a needle valve to discharge, stop, and control the dispensing amount, but in these types of dispensing guns, high static pressure is applied at the moment the needle valve opens. Therefore, when the valve is opened, a large amount of liquid may be temporarily discharged, causing uneven coating.Especially in handguns, there is a limit to the stroke of the valve lever, so the needle taper angle should be made gentler. As a result, the opening degree changes greatly due to minute movements of the valve rod, and the discharge amount tends to fluctuate extremely, making delicate adjustment of the discharge amount difficult.

Means for Solving the Problems The present invention provides a means for solving these problems, in which a trigger is provided in a pressure feeding passage for the application liquid formed in the gun body and communicating with the discharge port at the tip. A valve rod that moves forward and backward is inserted, and a needle valve is formed by a valve port provided at the tip of the pressure passage and a tapered needle portion formed at the tip of the valve rod corresponding to the valve port. , a stepped part formed in front of the needle valve of the pressure feeding passage, with a small diameter part on the front side in the pumping direction and a large diameter part on the rear side, and a rear end part with a slight gap between the small diameter part of the pressure feeding passage. A variable throttle valve is constituted by a valve body formed in the valve rod so that its cross-sectional area gradually decreases toward the front with a size to be fitted, and the variable throttle valve is configured to have a cross-sectional area that gradually decreases toward the front when the needle valve is in the closed state. The rear end of the valve body is located within the small diameter part, and when the needle valve opens to a certain opening degree or more due to the retreat of the valve rod, the rear end of the valve body moves from the small diameter part to the large diameter part. The present invention has the above-mentioned structure, and immediately after the needle valve is opened, the rear end of the valve body of the variable throttle valve is within the small diameter portion, and the flow area of the pressure passage is Because it is narrowed down to a very small amount, it is possible to prevent a large amount of liquid from being ejected instantaneously even when high static pressure is applied, and furthermore, in the subsequent retraction stroke of the needle part, it is possible to prevent the liquid from being ejected instantaneously. Since the cross-sectional area of the valve body gradually decreases and the flow area gradually expands, the flow resistance of the liquid gradually decreases from infinity as the opening degree of the needle valve at the tip of the gun increases. The amount of liquid discharged can be accurately adjusted by moving the needle portion back and forth by operating the trigger.

Embodiment Hereinafter, an embodiment in which the present invention is applied to a handgun for applying a sealant along joints of an automobile body after spot welding will be described with reference to the accompanying drawings.

In the figure, reference numeral 1 denotes a gun body, in which a pressure feeding passage 3 for sealing agent pressurized to a predetermined pressure is formed, which communicates with a supply passage formed in a grip part 2. A mounting cylinder 5 whose distal end protrudes from the gun body 1 is screwed into the mounting hole 4 whose distal end has an enlarged diameter, and its inner periphery forms a large diameter portion 5a. On the inner periphery of the
A cylindrical holder 6 having a diameter-reduced through hole 7 at its tip.
is screwed onto the top surface of the mounting cylinder 5, and the inner periphery of this holder 6 forms a small diameter portion 6a, and the sheet 1 has a central hole 11 transparently formed at its rear end.
0 is fitted, a chamfered valve port 12 is formed on the rear end side of the center hole 11, and a nozzle 13 having a discharge hole 14 is installed on the distal end surface of the holder 6 to attach a nut 15 to the cylindrical body 5. The valve rod 17 is fixed by screwing onto the protruding end of the valve rod 17, and the valve rod 17 is inserted into the center hole of a guide cylinder (not shown) whose rear end is fixed in the pressure feeding passage 3. A connecting body 18 having a flange 19 projecting from the outer periphery of the tip is fixed to the tip of the valve rod 17, which is fitted so as to move freely forward and backward, and a screw hole 2 formed in the tip surface of the connecting body 18 is fixed to the tip of the valve rod 17.
A valve shaft 21, which will be described in detail later, is fixed to the valve shaft 21 by screwing a threaded rod 22 protruding from its rear end surface. The rear end of a tapered needle 24 is press-fitted and fixed, and a needle valve 25 is formed by this needle 24 and the valve port 12 of the seat 10 described above.
The spring force urges the valve rod 17 in the forward direction to close the needle valve 25, and by pulling the trigger 27, the valve rod 17 moves backward against the spring force of the biasing spring 26, opening the needle valve 25. It's becoming like that.

As shown in detail in FIGS. 2 and 3, the valve shaft 21 has an outer diameter that is slightly smaller than the inner diameter (small diameter portion 6a) of the holder 6, and has an axially extending hole at its tip end. A valve body 28 having a constant width is formed at the rear end of the valve body 28, which has a rear end extending from a stepped portion 30 at the rear end of the holder 6 at a constant distance when the valve rod 17 is in the forward position shown by a solid line in FIG. A slope 29 is formed on the outer peripheral surface of the valve body 28 and is cut obliquely at a constant angle from the outer periphery of the rear end surface toward the front end surface.
Three valves are formed at intervals of 120 degrees, and a variable throttle valve 31 is formed by this valve body 28 and a stepped portion 30 at the rear end of the holder 6.
A ring 33 is fitted to the rear side of the valve body 28 on the outer periphery of the valve stem 20, and is capable of coming into contact with the rear end surface of the holder 6 and has an inner diameter slightly larger than the outer diameter of the valve stem 20. 33 and the above-mentioned connecting body 18
A compression coil spring 34 is installed between the flange 19.

Next, the operation of this embodiment will be explained.

Before pulling the trigger 27, the valve lever 17 is activated by the biasing spring 2.
6, the rear end of the valve body 28 enters into the holder 6 by a certain distance, and the tip of the needle 24 enters deeply into the center hole 11 of the seat 10, as shown by the solid line in FIG. The needle valve 25 is closed by being pressed against the inner periphery of the valve port 12, and the ring 33 on the rear side of the valve body 28 elastically compresses the compression coil spring 34 to be pressed against the rear end surface of the holder 6. When the needle valve 25 is opened by pulling the trigger 27 and retracting the valve rod 17 and the valve stem 21, the sealing agent supplied into the pressure passage 3 is released until the rear end surface of the valve body 28 hits the ring 33.
It flows through the gap between the inner circumferential surface of the ring 33 and the outer circumferential surface of the valve shaft 21 and the gap between the outer circumference of the rear end of the valve body 28 and the inner circumferential surface of the holder 6, thereby increasing the flow area of the pressure feeding passage 3. Even if a high static pressure is applied to the sealant, a large amount of sealant is prevented from instantaneously being discharged from the discharge hole 14, and the rear end surface of the valve body 28 is prevented from being discharged from the ring. 33, in the backward stroke, the ring 33 separates from the holder 6 and gradually retreats, and the valve body 2
8 retreats, the stepped portion 30 of the holder 6 and the valve body 2
8 and the slope 29 gradually increases, the opening degree of the variable throttle valve 31 gradually increases, the flow area gradually expands, and the needle 24
The flow resistance of the sealant gradually decreases from infinity as the opening degree of the needle valve 25 increases as the needle 24 retreats. Fine adjustments can be made accurately.

Therefore, when applying a sealant along the joints of an automobile body after spot welding, conventionally, for example, as shown in Figure 5, a large amount of sealant is applied instantaneously at the beginning of application. At the same time as dispensing, the speed at which the handgun is run is slow, so a wide coating width is created in the area a, and even at the end of coating, the handgun speed is slow, creating a wide coating width in the area b. However, if the handgun of this embodiment is used, the needle valve 25
Since a large amount of sealant is not instantaneously discharged immediately after the valve is opened, and the discharge amount can be finely adjusted by operating the trigger 27, the speed of the handgun can be adjusted as shown in Fig. 4. At the beginning of slow coating, pull the trigger 27 a little to suppress the discharge amount, and when the speed of the handgun increases, pull the trigger 27 to a larger amount to increase the discharge amount, as shown in A. It is possible to apply the coating to a constant width from the beginning, and by adjusting the amount of pull of the trigger 27 during the process, it is possible to arbitrarily form a narrow coating width part or a wide coating width part, for example, part B. At the end of coating, by returning the trigger 27 a little to suppress the discharge amount, C
As shown in Figure 2, coating can be done in a constant width until the end, and there is no uneven coating, giving a clean appearance, and the joints can be reliably rust-proofed.

Additionally, even if the joint is curved, the handgun must be run at a slower speed than in a straight line in order to apply the sealant along the joint accurately, which may result in a wider application width. By moving back a little and reducing the discharge amount, it is possible to apply the same width as the straight part.

In the above embodiment, even if the ring 33 on the rear side of the valve body 28 is not provided, the sealant is not applied until the rear end of the valve body 28 reaches the rear end of the holder 6 immediately after the needle valve 25 is opened. The flow acts through the gap between the outer periphery of the rear end of the valve body 28 and the inner circumferential surface of the holder 6, and the flow area is narrowed down to a small extent. Since the opening degree gradually increases and the flow area gradually increases, the ring 33 and the compression coil spring 34 may be removed.

Further, the present invention is not limited to the sealant application gun shown in the above embodiment, but can be similarly applied to an airless spray gun for painting.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view of an embodiment of the present invention;
FIG. 2 is a partially enlarged sectional view, FIG. 3 is a sectional view taken along the line A-A in FIG.
FIG. 5 is a diagram of a conventional coating pattern. 1: Gun body, 3: Pressure feeding passage, 6: Holder, 1
2: Valve port, 13: Nozzle, 14: Discharge hole, 17:
Valve rod, 21: Valve stem, 24: Needle, 25: Needle valve, 27: Trigger, 28: Valve body, 29: Slope, 30: Step, 31: Variable throttle valve, 5a: Large diameter section, 6a: Small diameter Department.

Claims (1)

[Claims] 1. A valve rod that engages with a trigger and moves back and forth is inserted into a pressure-feeding passage for application liquid that is formed in the gun body and communicates with a discharge port at the tip, and a valve rod provided at the tip of the pressure-feeding passage and the valve are inserted. A needle valve is formed by a tapered needle portion formed at the tip of the valve rod corresponding to the opening, and is formed in front of the needle valve in the pressure feeding passage so that the front side in the pressure feeding direction is a small diameter portion and the rear side is a small diameter portion. The valve rod is formed such that a step portion with a large diameter side and a rear end portion are sized to fit into the small diameter portion of the pressure feeding passage with a slight gap, and the cross-sectional area gradually decreases toward the front. A variable throttle valve is configured by the valve body, and in the variable throttle valve, when the needle valve is in a closed state, the rear end of the valve body is located within the small diameter portion, and when the valve rod retreats, the needle valve is closed. 1. A hand gun for application, characterized in that a rear end portion of the valve body is configured to retreat from the small diameter portion into the large diameter portion when the valve is opened to a certain opening degree or more.