Patent Application
20110239935
1. Field of the Invention
This invention generally relates to an apparatus for resin impregnation and, more specifically, to an apparatus for controlling resin impregnation of a fiber.
2. Description of Related Art
Traditionally, fibers are impregnated by passing them manually through a resin bath, using an applicator roller, or injection die. These methods require a high burden of manual handling, and typically do not result in non-uniform impregnation, and may result in the entrapment of air within the resin. This leads to a weakening of the part. Such methods and other can be found in U.S. Pat. Nos. 5,766,357, 6,387,179, and 6,179,945.
U.S. Pat. No. 7,413,623 describes many of the methods for resin impregnation of the prior art. U.S. Pat. No. 7,413,623 is incorporated herein by reference. U.S. Pat. No. 7,413,623 improves upon the prior art by employing the use of two roll impregnators, wherein the fiber passes through a resin pool directly above the two rollers. The resin pool resides sits above the two impregnation rollers and is held in from the sides by a set of dams. When the fiber passes through the two rollers, full impregnation is fostered, excess resin removed, and the impregnated fiber degassed. At least one of the two impregnator rollers can be adjusted to be closer or further from the other impregnator roller, allowing for control of the tension applied on the fiber. Outside of the two impregnation rollers is a set of alignment/tensioning bars.
U.S. patent application Ser. No. 12/208,322, published on Mar. 12, 2009, describes a system and method for using at least one roller to impregnate fibers with a liquid resin within a pressurized zone. The use of two rollers for impregnation with a pressurized zone at the output side of the rollers is also described.
None of the existing techniques for impregnation using impregnation rollers describe a convenient means for automatically adding resin to the resin pool. In addition, the existing techniques do not employ the use of temperature control for the resin pool or rollers, and the use of a latent catalyst system, which is automatically activated after the impregnation.
The present invention provides a novel apparatus for resin impregnation and wet-out of a fiber. The apparatus employs two impregnator rollers (nip rollers) for impregnating the resin into the fiber. A resin pool sits above the two impregnator rollers, and is held in on the sides by a set of dams. In one embodiment, two different resin pools exist, one for each side of the fiber. The resin pool may be filled automatically through a resin release mechanism. The resin may be mixed with a catalyst prior to being added to the resin pool to form a catalyzed resin. The resin is fanned into the resin pool(s).
In another embodiment, the impregnating rollers may have internal heating or cooling to control the temperature. Temperature may need controlled in order to maintain the proper viscosity of the resin.
If a latent catalyst system is utilized, the catalyst may be activated by heat or light. This is performed through the post-impregnation catalyst activator, placed below the impregnated rollers to automatically activate the catalyst after impregnation.
a is a top view of an embodiment of the dam;
b is a top view of an embodiment of the dam;
While this invention can take various forms, it generally provides a novel apparatus for impregnating resin onto a fiber, sometimes known as wet-out. The apparatus of this invention generally uses a two roller system to perform the impregnation. The novel features of the apparatus make this two roller impregnation system's usability and performance superior to previous ones. Usability and performance are enhanced through a set of features, as will be described in various embodiments of the invention below. The various embodiments describe a novel roller impregnator system comprised of gears, dual pooling of resin, a resin release mechanism, temperature control of the rollers, and a post-impregnation catalyst activation system.
Once the fabric is guided above the two guide bars 1, 2, the fabric makes its way between the nip rollers 6, 7.
The front nip roller 6 may be adjusted to be closer or further from the rear nip roller 7, to adjust the nip gap and accommodate different thicknesses of fabric. It is desirable for the nip rollers 6, 7 should be close enough to create enough pressure on the fabric for a few reasons. One such reason is to ensure adequate impregnation of the resin into the fabric. Another such reason is so the fabric will be pulled the nip rollers 6, 7. In a preferred embodiment, the rear nip roller 7 may be adjusted to be closer or further from the front nip roller 6 through an adjustment means.
In a preferred embodiment, the nip rollers 6, 7 are comprised of carbon steel, and are hollow. A large variety of other materials may be used to produce the nip rollers as known to those skilled in the art, and the nip rollers are not required to be hollow. A hollow nip roller may be more easily cooled or heated through various means, including water and steam. The cooling and/or heating of the nip rollers 6, 7 helps to control the temperature during the impregnation of the resin into the fabric.
Above the two nip rollers 6, 7 is a dam holder bar 9. The dam holder bar 9 has two attachment rods that protrude towards the nip rollers. These attachment rods each hold a dam 4, 5 at the bottom ends of the attachment rods. The dams 4, 5 are held to the attachment rods via a spring loaded mechanism to urge the dams 4, 5 towards the nip rollers 6, 7. The spring action allows for the dams 4, 5 to apply constant pressure between the dams 4, 5 and the nip rollers 6, 7. Also, by being spring loaded, these dams 4, 5 may be more easily removed and adjusted. Alternatives to spring loading include hydraulics or a compactable rubberized backing. However, spring loading or other alternative means are not required. Gravity may be sufficient, as the rotation of the nip rollers 6, 7 provide downward pull on the dams 4, 5. The dams 4, 5 prevent the resin in the resin pool, which sits above the nip rollers 6, 7, from flowing off the sides. Thus, it is important for the dams 4, 5 to provide a tight seal to prevent the resin from escaping. As such, the bottom part of the dams are shaped to be flush with the nip rollers 6, 7. The distance between the two dams 4, 5 may be adjusted to accommodate the width of the fabric. There are numerous other methods known to those skilled in the art for placing dams on the nip rollers.
The fabric is impregnated with the resin as it moves through the nip rollers 6, 7. The fabric is moved through the apparatus by way of friction and rotation between the nip rollers 6, 7. In a preferred embodiment, after the fabric passes the nip rollers 6, 7, it may be rolled around a receiver roller 8. The receiver roller is removable. The receiver roller 8 may rotate by use of the motor, and it is desirable for the receiver roller 8 to rotate at the same rate the fabric is being pushed out of the nip rollers 6, 7 (herein referred to as operational speed). E.g., if the nip rollers 6, 7 are pushing out the fabric at 10 ft per minute (operational speed), it is desirable for the receiver roller 8 to be rotating at a rate to roll up fabric at about 10 ft per minute (operational speed) as well. Rotation of the receiving roller 8 may be achieved by having a roller chain on the sprocket of the front nip roller 6 and sprocket of the receiver roller 8. The receiving roller 8, although useful, it not necessary.
The front nip roller 6 operates the rear nip roller 7 through gears. The front and rear nip rollers 6, 7 rotate in opposite direction to one another. With same sized gears attached to each nip roller 6, 7, the speed of rotation of both nip rollers 6, 7 are equal. Those skilled in the art understand that there are other possible known methods for rotating the nip rollers 6, 7.
The front nip roller 6 may also have sprockets so it may be chained to sprockets of a receiver roller 8. This allows for a single motor to rotate both the nip rollers 6, 7 and the receiver roller 8.
In other embodiments, various shapes of dams may be used to create a better seal between the dams and the fiber.
Though not required, the release preferably occurs by fanning the catalyzed resin into the resin pool for more controlled release. This may be performed by taking the catalyzed resin, outputted from the mixer 44, and releasing it into the resin pool using a spray head capable of fanning. Two separate resin release mechanism may be utilized if there are two separate resin pools on either side of the fabric. If the resin is not a catalyzed resin, then a mixer may not be required, and the resin can be pumped from the reservoir and released into the resin pool(s). The rate of release can be controlled by manually adjusting the rate of positive displacement. The rate of release may also be automatically associated with the rate the fabric is being pushed out of the nip rollers 6, 7 (operational speed). During operation, it is desirable for the resin pools to be replenished at the same rate the resin is being depleted. Thusly, the faster the operational speed, the higher the desired rate of release. And conversely, the slower the operational speed, the lower the desired rate of release.
It may be desirable to use a dormant catalyzed resin. A dormant catalyzed resin is a resin mixed with a catalyst, where the catalyzed resin is not activated until triggered by some activation means, such as heat. In such a scenario, a post-impregnation dormant catalyst activator may be utilized. The post-impregnation dormant catalyst activator can be utilized on either side of the fabric, and is placed in a location where it can act on the fabric after impregnation (i.e., after the fabric has passed through the nip rollers 6, 7). If the activation required is heat, the post-impregnation dormant catalyst activator may be infrared radiation for heating. Other methods of activating a dormant catalyzed resin include light, chemicals, and mechanical force. The activation intensity post-impregnation dormant catalyst activator may be controlled manually or controlled automatically by having a control correlate the activation intensity with the operational speed. This correlation is usually a positive correlation. For example, assuming the activation means is heat, the higher the operational speed, the stronger the desired heat produced by the post-impregnation dormant catalyst activator. In another example, assuming the activation means is light, the higher the operational speed, the stronger the desired light produced by the post-impregnation dormant catalyst activator.
Referring to
Although only referred embodiments has been described herein, many modifications will become readily apparent to one skilled in the art.
