JPH03166057A - Grinding material feeding system - Google Patents

Abstract

PURPOSE: To apply wet or dry spray cleaning with an abrasive such as sodium bicarbonate by feeding the flow of sodium bicarbonate grains mixed in air to the air/abrasive inlet of an inner propulsion chamber. CONSTITUTION: A hopper 100 contains a moisture-sensitive abrasive such as potassium bicarbonate or corncob grains, and the hopper 100 is pressurized by dry gas such as nitrogen stored in a cylinder 101. Nitrogen is fed into the hopper 100 through a pipe 102, a cutoff valve 103, a regulating valve 104 and a check valve 105. The compressed air in a pipe 110 is fed to a drier, i.e., a moisture separator 113, through a large-capacity pressure regulating valve 112, then it is fed to a pipe 117 passing below the bottom of the hopper 100 through a cutoff valve 114, a regulating valve 116 and an automatic cutoff valve 116. The pressurized flow of abrasive grains flows down in a feed pipe 118 and is fed to the joint of a pipe 117 through a measuring valve 119.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a liquid-propelled abrasive cleaning system, particularly for selective abrasive cleaning for removing coatings or coatings from materials to be cleaned without damaging the substrate. Regarding the system.

[Conventional technology]

When removing coatings from aircraft, fiberglass boats, etc., a selective abrasion system is desirable and necessary to allow repainting if necessary. Such systems do not damage the underlying metal or other base materials.
It must be possible to remove the paint film. Conventional sandblasting paint removal can create excessive anchoring on thin aluminum sheets. Plast particles such as crushed walnut shells and plastic buttons have been tried. With these particles, brittle coatings could be removed, but with flexible urethane coatings, the particles were too elastic and would bounce back. Agricultural products such as rice husks and corn cobs have also been tried, but the particles are small and sharp and the aluminum cuts too deeply. The problems in obtaining a satisfactory flow of these types of abrasive particles are largely unsolvable. Some agricultural abrasives contain oil, which poses a fire and explosion hazard, and leave oil residues that impair paint adhesion. Therefore, stripping and repainting paint on large commercial aircraft in particular can cost hundreds of thousands of dollars.
There has been a need for effective selective polishing systems.

Of course, coating removal methods that also remove significant amounts of metal should be avoided for safety reasons.

[Problem to be solved by the invention]

Applicants have determined that the coating has sufficient sharpness, density, and hardness to cut through and remove coatings without damaging the underlying aluminum, fiberglass, or carbon fiber laminates.
I have been searching for an abrasive that is compatible with a wet spray stripping system. As a result of the applicant's investigation, the Mohs hardness scale was approximately 3.
It has been found that it is necessary to use abrasive particles that have a scratch hardness that is less hard than that of aluminum, and if possible is slightly softer. Sodium bicarbonate has been found to be an excellent abrasive material for the above applications. Sodium bicarbonate has a Mohs hardness of about 3, its density is the same as traditional blast particles such as sand, and it has good mass. This material is relatively inexpensive and readily available in large quantities and in a variety of particle sizes.

Testing of wet cleaning systems has demonstrated that satisfactory results are obtained using water pressures in the range of 1500-2000 psi with 60 psi air pressure.

However, because the flow of sodium bicarbonate particles from the abrasive hopper was somewhat irregular and inconsistent, this method was considered impractical for use outside of the laboratory. Applicants therefore sought and found a solution to this problem, which is the subject of the present invention.

A general object of the present invention is to provide a new and improved abrasive delivery system in wet or dry spray cleaning processes in which abrasives such as sodium bicarbonate can be used.

Another object of the present invention is to provide a new and improved liquid propelled abrasive spray cleaning system for selective abrasive use using sodium bicarbonate particles as the abrasive material.

[Structure and effects of the invention]

For these and other purposes, a nozzle system that supplies a high-pressure water stream and accelerated sodium bicarbonate particles to remove coatings from surfaces such as sheet aluminum, and a pump that delivers pressurized water and air to said nozzle system. a wet spraying system comprising a system and a compressor system and a hopper system for delivering pressurized bicarbonate particles to said nozzle system where a jet of water propels the particles onto the surface to be cleaned. The concept of the present invention achieves this by providing the following.

To create a regulated flow of sodium bicarbonate particles from the hopper, a drying gas such as nitrogen is supplied to the hopper at a regulated pressure such that the chlorine particles flow into the air leading to the nozzle system at a pressure greater than or equal to the supply air pressure. Let it enter the conduit.

In this method, compressed air containing moisture is prevented from entering the hopper and a regular flow of a controlled amount of abrasive particles is sent to the air line leading to the nozzle system. In addition to using abrasives such as sodium bicarbonate, the system can also use a variety of other abrasive particles that were previously unavailable due to the lack of moisture in the compressed air used to pressurize the hopper. The result is selective abrasive action in a highly efficient and effective manner.

〔Example〕

First, FIG. 1 will be explained. This figure is from June 1986.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a prior art liquid propelled abrasive spray cleaning system of the type shown in Co-pending Application No. 8,729,095 filed in May and assigned to the assignee of this invention. The system comprises an air compressor 10 driven by a suitable motor 11 for supplying pressurized air to a line 12;
Preferably, the capacity should be in the range of 30 to 90 cfm plus about 180 cfm required to operate the spray nozzle.

Acceleration air is routed from line 12 via branch line 30 and air isolation valve 15 to control station or cabinet 14.
will be sent to The feed water is conveyed to the lower part 16 of station 14, which comprises a storage tank having separate compartments for water and antioxidant. Pneumatically operated bomb 21
(shown in dotted lines in FIG. 1) is housed within a control station 14 by means of which water containing a controlled amount of antioxidant is supplied under high pressure to the inlet of the spray nozzle 23. the output hose 22.

The hose 22 is relatively long, e.g.
50 feet} (7625ao) in length. Control valve 2 is a normally closed "dead man system"
4 is mounted adjacent to the nozzle member 23, and the operator pushes a spring-loaded actuator handle to release the control valve 24.
When the nozzle is not held in the open position, it acts to prevent the nozzle from operating. In this manner, all flow of high pressure water and abrasive particles to the nozzle member 23 is automatically shut off when the operator releases the handle or if the nozzle member is accidentally dropped. The inlet of the control valve 24 is a flexible conduit 25
is connected to a T-joint 26 of a conduit 27, and the conduit 27 communicates with the main air supply conduit 12 by a T-joint 28. An air cutoff valve 29 is disposed between the T-joints 28 of the conduit 27. The outlet of the control valve 24 is connected by another flexible conduit 31 to a suitable fitting on the side of the upper part 13 of the control station 14. This causes a pneumatic signal to be sent to the control station 14 when the control valve 24 is actuated.

The nozzle member 23 does not need to be described in detail, but includes a tubular body with a propelling chamber, an inlet for abrasive particles, an inlet for water, and an outlet for atomizing the water and propelled abrasive particles. Be equipped. The control valve 24 comprises a body attached in a suitable manner by a hose 38, which body has an inlet for the line 25 and an outlet for the line 31. A spring-loaded handle is pivotally attached to the body and, when pushed by the operator, opens a valve element within the body to provide communication between conduit 25 and conduit 31. When the handle is turned, the valve automatically closes and line 25 is no longer in communication with line 31. Shutoff valve 2o connects line 22 to the water inlet of nozzle assembly 23.

Further, the ml diagram will be explained. #3 Abrasive particles, such as sand, are placed in a hopper or “pot” 33;
This hopper is filled with a suitable amount, for example 1000 bonds (45
The thickness should be large enough to hold 0 kg of abrasive material. Pressurized air from line 12 enters tank 33 through a regulating valve 34, a shutoff valve 35 in branch line 36 from Tll hand 37 of line 27, and from a suitable fitting. Therefore, pressure is applied to the tank 33. A sand feed line 38 leads from the bottom of the tank 33 to a TII port that connects the air line 27 and a feed line 38 leading to the sand inlet of the nozzle member 23 . A pilot-operated sand metering and shutoff valve 39 is located in line 38 next to hopper 33. Valve 39 is normally closed and opens in response to air pressure in line 41, which is connected to air signal line 31 by means of Tll handles 42 and 43 branch line 44. Three-way valve 45 of pipe line 41
is equipped with an air bleed port that allows air pressure to be manually released when necessary. The line 27 coming from the air supply line 12 is
Line 44 leads to a normally closed air valve 46 having a pneumatic actuation system. therefore. control valve 24
Valve 4 opens only when the pneumatic signal flows through line 31.
6 is activated. Therefore, a metered mixture of sand particles and air is delivered to the line 38 only when the nozzle member 23 is activated.

The internal and external components of the station 14 are described in the aforementioned Application No. 8.
72.095, so only a summary will be given here. Monitor system operation using appropriate indicators, gauges, pump stroke counters, and water valve actuator handles. The system shown in FIG. 1 provides excellent cleaning when an abrasive material such as sand particles can be used. To enable the use of abrasives such as sodium bicarbonate in accordance with the present invention, the structure shown in FIG. 2 is used.

FIG. 2 will be explained. Hopper or "pot" 1
00 contains sodium bicarbonate or other moisture-sensitive abrasives such as potassium bicarbonate or corn cob grains, but this hopper is not abrasive by compressed air (which contains moisture). , is pressurized by a dry gas such as nitrogen contained in cylinder 101. Nitrogen is fed into the hopper 100 through a pipe 102, a cutoff valve 103, a regulating valve 104, and a check valve 105. The compressed air in line 110 is sent to a dryer or moisture separator 113 through a large-capacity pressure regulating valve 112, and then passes through a shut-off valve 114, a regulating valve 115, and an automatic shut-off valve 116 to the bottom of the hopper 100. It is fed into the conduit 117 passing below. The flow of pressurized abrasive particles is carried through the feed line 11
8, passes through a metering valve 119, and is sent to a T-joint in conduit 117. A mixed stream of abrasive particles, nitrogen, and compressed air is then directed to the abrasive particle inlet of nozzle assembly 23 (FIG. 1).

In order to prevent air from the pipe line 117 from entering the hopper 100,
The regulating valve 1 is installed so that the internal pressure of the hopper containing the sodium bicarbonate particles is always higher than the pressure of the spray pipe 117.
It is desirable to combine 04 to 115 with each other. Functionally separate regulating valves can be used, but each must have a high sensitivity. By utilizing the magnitude of the positive differential pressure, it is possible to control the weight per unit time of sodium bicarbonate used in paint film removal work with extremely high precision. The present invention thereby provides a highly effective metering system for abrasive particles depending on the operating conditions.

As an example of the operation of the system of the present invention, the blowing line 11
The pressure of the compressed air in No. 7 is 100 psl, and the flow rate is 2 0 0.
cf'a, the nitrogen gas in the pipe line 102 is transferred to the hopper 100
shall be adjusted so that the pressure is maintained at 102 ps1. A positive differential pressure of 2 psl allows controlled delivery of abrasive particles into conduit 117 leading to nozzle assembly 23. In the embodiment shown in FIG. 2, the abrasive material can be fed by gravity when the pressures in the hopper and feed tube are equal. The amount of abrasive particles can be very precisely controlled by controlling the differential pressure between the feed line pressure and the hopper pressure, for example 10 Bonds per minute.
5kg) or 600 bonds (270kg) per hour. Since nitrogen gas does not contain moisture, pipe line 11
The flow of sodium bicarbonate abrasive to No. 7 is very uniform for optimum coating removal results.

Another embodiment of the invention is shown in FIG.

Hopper 200 comprises a fluidized bed of sprayed particles 201 in region 199 above porous membrane 202 . A region 203 below the membrane 202 is supplied with a drying gas, such as nitrogen, from a cylinder 204 via a regulating valve 205 . A spray particle inlet conduit 206 with a flare-shaped inlet 207 passes through the top of the hopper 200 and is connected to a spray conduit 209 by a YtI1 handle 20g. A blow line 209 connects a large capacity compressed air supply system 210 to a dryer 214 and a regulating valve 21.
1 to the Y joint 208. The vent line 212 is always closed by a valve 213.

The system shown in FIG. 3 has the advantage that fluidizing gas can be utilized to dry abrasive material containing moisture, thus allowing abrasive material that would otherwise be wasted to be recovered for use.

In operation, region 203 is supplied with a very clean dry gas, such as nitrogen, from cylinder 204, which passes through porous membrane 202 to region 199 above the membrane.
"Fluidize" abrasive particles such as sodium bicarbonate within. The pressure in region 203 may be, for example, 103 psi and the pressure in region 19 may be approximately 102 psl. The pressure in the spray line 209 is adjusted to 100 ps1, and the flow rate is 200 cf+g.

The abrasive particle flow rate downstream of the Y-joint 208 is such that the abrasive fluidized density is 50 bonds per cubic foot (22.
5 kg), it becomes 10 bonds per minute (600 bonds per hour). The flow rate can be controlled with great precision by varying the differential pressure, depending on the operating conditions of the cleaning or coating stripping operation. Because there is no moisture in hopper 200, abrasive materials such as sodium bicarbonate can be used to strip coatings from aluminum or fiberglass substrates without damaging the metal or glass fibers.

Although nitrogen has been recommended as the gaseous medium for use in the present invention, other non-flammable dry gases such as carbon dioxide or helium can also be used. Various abrasive particles can be used that were previously not possible due to flow issues.

[Brief explanation of the drawing]

Figure 1 is a schematic representation of a prior art wet spray cleaning system using sand particles as an abrasive; Figure 2 is a pressurization in which sodium bicarbonate can be used as an abrasive to selectively remove paint from a substrate. FIG. 3 is a schematic diagram of one embodiment of a hopper, valve and piping system; FIG. 3 is a schematic diagram of another embodiment of the invention; FIG. 100...Hopper, 101...Cylinder, 103,1
114.116...Shutoff valve, 104,112.115
... Regulating valve, 105 ... Check valve, 113 ... Dryer, 116 ... Automatic shutoff valve, 119 ... Metering valve, 2
00...Hopper, 202...Porous membrane, 204...
Cylinder, 205, 211... Regulating valve, 214... Dryer.

Claims (1)

[Claims] 1. Cleaning surfaces such as paint and corrosion using an internal propulsion chamber of the body having an outlet communicating with the internal propulsion chamber through the body, a water inlet, and an air and abrasive inlet. supplying high pressure water to the water inlet of the propulsion chamber; and to the air and abrasive inlets of the internal propulsion chamber;
providing a stream of air-entrained sodium carbon particles; accelerating the sodium bicarbonate particles with high pressure water in the internal propulsion chamber and blowing them out at high energy from the outlet of the propulsion chamber; Directing an outlet of an internal propulsion chamber toward said surface to be cleaned. 2. In the method of cleaning structural surfaces such as paint films and corrosion, a water inlet communicating with an internal chamber, an air and abrasive inlet,
providing pressurized water to the water inlet of the chamber; and supplying pressurized water to the air and abrasive inlets of the chamber; A method of cleaning comprising: providing a flow of material particles; and directing an outlet of the chamber toward the surface to be cleaned. 3. The cleaning method according to claim 2, wherein the water-soluble abrasive contains sodium bicarbonate particles. 4. The cleaning method according to claim 2, wherein the water-soluble abrasive contains potassium hydrogen carbonate particles. 5. said stream of water-soluble abrasive particles entrained in air enters said air and abrasive inlet at an inlet velocity, said pressurized water and said air and abrasive interacting within said internal chamber; 3. The cleaning method of claim 2, wherein air, water, and water-soluble abrasive particles are atomized from the outlet of the chamber, the atomization velocity being greater than the inlet velocity of the water-soluble abrasive particles. . 6. The cleaning method according to claim 5, wherein the water-soluble abrasive contains sodium bicarbonate particles. 7. The cleaning according to claim 5, wherein the water-soluble abrasive contains sodium hydrogen carbonate particles, and the hardness of the surface of the structure to be cleaned, such as a coating film or corrosion, is approximately the same as that of the sodium hydrogen carbonate particles. Method. 8. The cleaning method according to claim 7, wherein the surface of the structure to be cleaned is made of aluminum. 9. The cleaning method according to claim 7, wherein the surface of the structure to be cleaned contains glass fibers. 10. The cleaning method according to claim 7, wherein the surface of the structure to be cleaned includes a carbon fiber laminate. 11. the pressurized water in the internal chamber propels the water-soluble abrasive particles out of the outlet of the internal chamber;
3. The cleaning method of claim 2, wherein a spray stream is created that includes water and water-soluble abrasive particles of sufficient energy to remove said coating, corrosion, etc. from said underlying structure surface. 12. The cleaning method according to claim 11, wherein the water-soluble abrasive contains sodium bicarbonate particles. 13. A new method using a chamber comprising a body forming an internal chamber and having a water inlet, an air and abrasive inlet, and an outlet in communication with the internal chamber, comprising: supplying an inlet with a flow of abrasive particles including airborne sodium bicarbonate particles; supplying pressurized water to the water inlet of the chamber; and directing the outlet of the chamber toward the surface. A method of cleaning said surfaces, such as paint films and corrosion, thereby, without damaging said surfaces. 14. The method of claim 13, wherein the surface to be cleaned has approximately the same hardness as the sodium bicarbonate particles. 15. The pressurized water in the internal chamber contains water and sodium bicarbonate particles of sufficient energy to accelerate the sodium bicarbonate particles through the outlet of the internal chamber and clean the surfaces, such as coatings and corrosion. 14. The method according to claim 13, wherein the spray is sprayed out.