BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic illustration of the so-called rubber shim stock, which is received in large diameter coils and of which a portion is shown just beginning to be unrolled from the coil;
FIG. 2 schematically illustrates plural, equal lengths of the rubber shim stock being cut after being taken from the coil;
FIG. 3 is a schematic vertical sectional view of the rubber shim stock, showing liquid adhesive being affixed to the two end portions thereof, and showing the shim stock about to be formed into a circular loop;
FIG. 4 is a schematic vertical sectional view showing the end portions of the rubber shim stock when the ends are fully bonded to each other to form a circular loop;
FIG. 5 schematically shows a circular piece of rubber shim stock being stretched to a larger radius so as to fit over a casing, showing the manner in which the liquid adhesive is added to the OD of the metal casing, and showing the rubber shim stock in the process of being allowed to return to just more than its totally relaxed diameter;
FIG. 6 is a vertical sectional view of a seal casing with the rubber comprising the seal body already inserted into the steel casing and bonded in place;
FIG. 7 shows the casing with the rubber shim stock bonded thereto by the use of the adhesive shown in FIG. 5, and;
FIG. 8 shows the rubber OD being trimmed to impart a chamfer to the shim stock on both axial sides of the seal.
DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
While the invention may be practiced by the illustrated methods or by somewhat different methods, and the seal made thereby has several features of novelty, an illustration will be given of one preferred method of making a seal, and the resulting seal having a rubber OD with a selected amount of shim stock bonded thereto.
Referring now to the drawings in greater detail, there shown in FIG. 1 a coil generally designated 20 of rubber so-called shim stock 22. This shim stock 22 is shown as being unrolled at 24 wherein an individual piece is taken from a much longer roll. It will be understood that this drawing is schematic and that the shim stock in question, usually 0.094 inches in thickness, comes in several hundred foot lengths. In this case, for illustration, the shim stock is cut into two individual pieces 26, 28, (FIG. 2) each having end portions 30, 32 spaced apart in selected, predetermined lengths. The lengths 26, 28 of each section of shim stock are treated successively. In FIG. 3, there is shown one such piece 26 having two end portions 30, 30 in the presence of a liquid adhesive 34. The first liquid adhesive 34 is a powerful, contact adhesive which enables the two ends 30, 30 to be bonded together into a continuous loop 36 as shown in FIG. 4.
FIG. 4 shows the completed loop 36 made by bonding two ends of the loop 30, 30 together. FIGS. 5, 6 and 7 show the next steps in the process. FIG. 6 is a drawing showing a cross section of a large diameter seal. Here, there are shown the main components of a large diameter seal, namely, the body generally designated 38, and including frusto-conical air and oil side surfaces 40, 42 meeting along a line of intended contact 44 with the shaft 45. These surfaces are sometimes referred to as the inside face, or oil side 42 of the seal, and as the outside face, or air side 40 of the seal. The seal body of 38 is shown to include a curvilinear, generally somewhat circular, contoured opening 46 and an upper or radially outward portion 48 of the seal body 38. This seal body or elastomeric portion 38 is received within a casing generally designated 50 and shown to include a principal, axial portion 52 and a pair of radial flanges 54, 56.
These flanges 54, 56 are produced by spinning the an originally flat portion 52 until the correct curvature and the desired flanges 54, 56 are obtained. Thereafter, the seal body 38 is formed and placed within the casing generally designated 50. Needless to say, the seal could be reversed and the flanges directed outwardly.
Referring now to FIG. 5, there is shown a stretched portion of rubber shim stock surrounding the portion 52 of the casing. The rubber portion 26 is shown as being somewhat spaced apart from the axial portion 52 of the casing. Liquid adhesive 58 is shown schematically as being deposited on the axial portion 52 of the casing, and the piece of shim stock 26 as having had its end portions secured together. A loop 26 is then formed and the loop 26 having been stretched to a larger diameter than that of the flange 52. The forces holding the shim stock spaced apart from the flange 52 are then released, allowing the shim stock 26 to contact the casing 50 through the adhesive. In FIG. 7, it is shown that the shim stock is now bonded to the casing, and has become a permanent fixture.
Referring now to FIG. 8, there are shown two knives 60, 62, which are positioned spaced apart but adjacent the edge portions 66, 68 of the shim stock, and they are thereafter moved into position so as to trim these edges 64, 66. This cuts out small strips 68, 70, from the shim stock 26 overlying the axial portion 52 of the casing 50. Thereupon, the new large diameter seal is ready for installation.
Referring now to certain aspects of the invention and the method of performing it, preferably the rubber used is initrile (Buna N) rubber, but other synthetic rubbers and other rubbers such as natural rubber, silicone rubbers and other kinds of rubber could be used. The adhesive 34 used is a fast setting, clear cyanoacrylate adhesive, which bonds the rubber ends together and which is further identified as a room-temperature curing adhesive, for example, Locktite 420. This rubber is ready for the next step almost immediately. This loop of rubber is then sanded lightly to render the surface suitable for bonding with the next adhesive. The rubber is stripped of any residual oil.
The second process starts by cleaning the metal of any oil, etc. used in forming the metal casing. Next, applying the rubber to the casing 50—is done by applying a similar adhesive—Locktite brand 4212 or 4211, to the metal casing. Both adhesives are described as thermally resistant (250° F.) high viscosity toughened adhesives. The next step involves stretching the one-piece band 26 of rubber to about 105% to 125% of its relaxed length, and covering the casing with such rubber band. The rubber should have no less length than 102%, and up to 110%, of the length in its relaxed condition. The bond will form in about 5 minutes, and the joint is then allowed to cure for 24 hours.
After a suitable curing period of 24 hours or more, the knives or razor blades may be used to trim the chamfer on one or both sides of the rubber OD coating. Normally, this is done by placing the inclined blade on the edge of the casing and rotating the casing until the margin of the rubber have been trimmed off. A 30 degrees from the horizontal is preferred.
It will thus be seen that the invention provides a novel seal and method having a number of advantages and characteristics, including those herein pointed out and other which are inherent in the invention.
Patent Application
20080001365
