Rotary atomizer and bell cup and methods thereof

Details Rotary atomizer and bell cup and methods thereof Rotary atomizer and bell cup and methods thereof

2000-10-19

2002-01-29

Scherbel, David A. (Department: 3752)

Fluid sprinkling, spraying, and diffusing

Slinger or splasher; or deflector rotated relative to effluent

Disc impeller type or bowl-like slinger or deflector

C239S112000, C239S222000, C239S224000

Reexamination Certificate

active

06341734

ABSTRACT:

BACKGROUND
An electrostatic painting device typically uses a rotary atomizer to atomize paint or coating material. A rotary atomizer typically includes a bell shaped body (“bell cup”), which is typically used, but not exclusively, in painting motor vehicles. The bell cup is mounted to one end of a rotatably mounted shaft, which is typically driven by an air motor. The bell cup is generally spun at a relatively high speed, to about 70,000 RPM, to generate sufficient centrifugal force to atomize the coating material exiting the bell cup's spray edge into a super fine mist.
Different bell cups may have different shapes and configuration to offer a variety of flow shapes and rates. Air can be supplied through a shroud that is concentrically positioned over the bell cup, adjacent to where the atomized coating material leaves the bell cup, to direct the atomized coating material to the object to be coated.
The bell shaped body can have a cavity defining an inner flow surface that communicates with the coating material source and a spray edge contiguous with the inner flow surface at the front or distal end of the bell shaped body. The bell cup is typically rotated around a stationary nozzle having a passageway or channel for the coating material.
One known problem with a bell cup atomizer is that coating material can accumulate on the outer exposed surfaces of the bell cup. During use, the accumulated (old) coating material can dislodge from the bell cup and undesirably mix with the new coating material, especially after changing the paint. Therefore, it is highly desirable to clean the outer surfaces of unwanted material.
One solution is to separately feed solvent or jet air to the outer peripheral surfaces to remove or prevent the unwanted material from adhering thereto. See for example, U.S. Pat. Nos. 5,862,988, 5,707,009, and 5,106,025. Another solution, as disclosed for example, in U.S. Pat. No. 5,707,009, uses a stationary nozzle having a plurality of channels that are separate from the coating material channel for delivering solvent to the inner flow surface and the outer surface of the bell cup. Since the solvent channels are independent from the coating material channel, the bell cup can be rinsed with solvent (rinsing or cleaning agent) without having to remove the paint from the paint channel. The feed nozzle, which is coaxially arranged with the bell cup, delivers solvent or coating material from the rear or proximal end of the bell cup through passages formed in the flow control device, e.g., an insert or face cover, of the bell cup.
In U.S. Pat. No. 5,707,009, the bell cup has an annular cavity located at the rear section of the bell cup, communicating with the solvent channels. The annular cavity creates a reservoir by which solvent flows via the rearward edge onto the outer periphery of the bell cup. During use, while the bell cup undergoes painting operation, the annular cavity is prone to paint accumulation. Thus, there is a need for a better way of cleaning the outer periphery of the bell cup. The present invention addresses this need.
Known bell-cup atomizers are typically monolithically formed (single-piece construction), typically machined from a single block of aluminum. In this vein, a typical bell cup atomizer has a bell cup integrally formed with a flow control device typically comprising a front cover or bell cone covering a portion of the cavity. The front cover or bell cone has a front side having exit passageways. The backside or the proximal end of the bell-cup atomizer has a rather relatively small passage through which the machining or cleaning is accomplished.
In practice, the atomized coating material can adhere to the surfaces of the bell cup and impede the flow of the coating material through the exit holes. Consequently, the bell cup must be cleaned frequently. Thorough cleaning of known bell cups entails detaching them from their manifold to access the internal surfaces. Even after detaching it, the narrower or smaller opening at the proximal end of the bell cup makes cleaning difficult.
Further, various stages of a coating operation may require different flow configurations of coating materials and, thus, require a different exit hole arrangement. With known bell cups, the entire bell-cup atomizer must be detached from the manifold, and an entire new bell-cup atomizer must be attached. This procedure must be repeated each time the coating operation calls for a change in the flow configuration of the coating material.
Accordingly, there is a need for a better way of accessing the internal surfaces of the bell-cup atomizer and a more economical way of manufacturing and using the same. In this respect, U.S. Pat. No. 5,707,009 addresses this problem with a detachable flow control device (insert) comprising a front cover and a ring unit. The present invention also addresses this need.
Further, a bell-cup atomizer with the integral flow control device or the detachable insert typically has radially or outwardly extending channels through which the paint exits. The bell-cup atomizer or the detachable insert can be formed with a curved or flat wall surface. The present inventor has found that paint can build up on that wall surface even after undergoing a wash cycle. Accordingly, there is a need for a bell-cup atomizer or detachable insert that stays cleaner around the exit side of the channels. The present invention also addresses this need.
SUMMARY
The present invention relates to a coating device, such as a rotary atomizer, a bell cup thereof, and a detachable flow control device thereof, and methods thereof. The rotary atomizer has a bell cup, i.e., a rotatable body. The bell cup can have a provision for cleaning the outer surface thereof and/or a provision for enabling access to inside, i.e., a cavity thereof, for easier cleaning and/or to alter the flow pattern.
The rotatable body can have a cavity defining an inner surface, an outer surface surrounding the cavity, and a spray edge located at a distal end of the rotatable body, where coating material to be atomized leaves the rotatably body. The rotatable body further can have a first axial passage through which a coating material to be atomized or a cleaning agent can be delivered to the cavity. The rotatable body has a plurality of cleaning passages extending from the first axial passage to the outer surface of the rotatable body. The cleaning passages are adapted to deliver cleaning agent to the outer surface. Moreover, the outer surface of the rotary body is deliberately devoid of any fluid accumulating recess or reservoir to enable the cleaning passages to feed the cleaning fluid onto the outer surface without accumulating or storing the cleaning agent or the coating material on the outer surface.
The rotatable body can be substantially bell shaped, having an open distal end and a proximal end opposite the distal end, and a hub portion extending axially from the proximal end of the bell shaped body. The outer surface can extend from the hub portion to the distal end. The first axial passage extends concentrically with the hub portion and extends through the proximal end of the bell shaped body to communicate the first axial passage with the cavity. The cleaning passages can extend outwardly and forwardly toward the proximal end of the bell shaped body.
The rotary atomizer can further include a rotatable shaft connected to the rotatable body. In this respect, the hub portion can include a first mechanical connector, such as external or male threads, and the rotatable shaft can include a second mechanical connector, such as internal or female threads, that is complementary to the first mechanical connector.
A stationary nozzle can be used to deliver the coating material and the cleaning agent. In this respect, the nozzle can have a first passage adapted to deliver the coating material to the cavity, at least one second passage adapted to deliver the cleaning agent to the cavity, and a third passage branching off from the second passage. The nozzle can extend into the first axial passage

Affiliated with

Also associated with

Rating

Rotary atomizer and bell cup and methods thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Rotary atomizer and bell cup and methods thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rotary atomizer and bell cup and methods thereof will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2842207