US 2725693 A
Description (OCR text may contain errors)
Dec. 6, 1955 J. L. SMITH ABRASIVE ROLL AND METHOD OF MAKING Filed Dec. 15, 1954 O%INVEN TO-R.
AERASWE ROLL AND METHODOF MAKING Joseph Leigh Smith, Glen Ellyn, 'Ill.
Application December 15, 1954, Serial No.475,527
6 Claims. (Cl. 51-190) This invention relates to an abrasive roll and to a method of making it. An abrasive roll is a strip of emery cloth rolled around a small center mandrel into a cylindrical shape, the roll being held in assembled re lationship by means of a layer ofiglue which may extend the full length, half the length, or one-quarter the length of the roll. This layer ofadhesive is to be distinguished from the layer of adhesive which holds the abrasive grain to the cloth. There is some-commercial demand for rolls having a conical shape.
These rolls under heavy -duty-come apart due to the heating of'the adhesive'which becomes weak. A study of a roll which has come apart shows .no-constantpattern of the line of separation between the glue, the abrasive surface and the cloth surface. Referring to Figure l of the-drawings, applicantshows a small roll which has come apart-during hard usage. The strip is indicated by the numeral fill. The upper surface 14 is the clothwhile the lower surface 12 which becomes the outside of the roll is covered with emery dust or other abrasive grain which isheld to theclothbyaglue or other adhesive. The separated roll shown in Figure 1 was coated with adhesive throughout-its entire length so that theentire surface 140i the-clothcarried adhesive. As the strip it? was rolled up, the glue was press-ed upon the cloth surface 14. The heavier-the gluecoating, the more completely is the abrasive ggrain wetted. This means that asthe roll is worn-throughvone surface to the next, an additional layer of ;glue must be penetrated before reaching the-abrasive. If the glueis applied sufficiently thickly, it willncompletely .flood the abrasive grain. This impairs the effectiveness ofthe emery-cloth because the glue actsas a lubricant. What is wanted is an abrasive grain surface that is completely free of glue.
-Returning to Figure Lshowing theseparated roll, the surface 14% carries almost acontinuoumglue layer. There can be found adhering to this glue a few abrasive grains. There is practically no hardened glue adhering to the surface 12. This indicates that the thickness of the layerof glue, its particular properties tending tohold it to the fabric as contrasted to the grains, and the extent of its being compressed during the rolling step, was approximately right from #the istandpoint of grinding. It, however, did not hold the'rollin cylindrical shape and hence became useless.
The commercial roll Which has been heavily ,glued only one-quarter of the 'lengthisan attempt to hold together threeequarters of "theroll, whose grinding properties are good, by means ofone-quarter of the roll, whose grinding properties have been impaired by 'au'excess of glue.
The object of this invention is to provide a glue bond of great strength at limited points on the roll and to do this by removing from the surface of the roll small areas which will not participate in a grinding operation.
A first feature of this invention is the application of a layer of glue of a thickness such that it will not flood States Pate t O the abrasive grain surface, but at selected points, to press the surface inwardly either by small circular areas or by a groove completely around theroll. The effect is to flood the abrasive grains with glue at those points where the indentations have occurred, thereby giving added strength to the bond.
One important advantage from applicants structure is the fact that the abrasive grains on the surface at the point of indentation do not engage the workpiece which is being ground. Consequently, these abrasive grains acquire heat'only by transmission from adjacent-abrasive grains and in turn, less .heat is transferred to the glue which consequently-does not soften so readily.
Another object of this invention is to provide a method of making these rolls which will he inexpensive and fast.
These and such other objects-asmay hereinafter appear are shown in .the embodiments of the invention shown in the accompanying drawings, wherein:
Figure l is a perspective view of an existing type of roll which has come apart;
Figure 2 is a perspective view of one of app'licants rolls having an annular circumferential groove near one end;
Figure 3 is a sectional view of a portion .of applicants roll taken on the line 3-.3 of Figure 2;
Figure 4 is an enlargement of that portion of Figure 3 which is within the dot-dash line;
Figure 5 is aperspective view of a modified form of applicants roll;
Figure 6 is a perspective view of'another modified form of applicants roll;
Figure 7 is a perspective view of still another modified form ofapplicants roll; and,
Figure 8 is aperspective, schematic view of two rollers between which applicants preferred form of roll, shown in Figure 7, :is being formed.
Continuing to refer to the drawings, and particularly to Figure 2, applicants roll consists of a rectangular strip 16 of emery cloth rolled spirally into a cylinder with'the emery surface 18 outside. Assuming that the roll shown is a three-eighths inch diameter roll, having a length of one inch, there is provideda circular groove 19 extending around the roll spirally inwardly to the very core.
An enlarged, longitudinalsection of aportion of this roll .is shown in Figure 3, where vthe fabric is indicated by the numeral v2i), the .emerypowder by .the numeral 22, the glue holding the emery .powder to the fabric by the numeral 24, and .the glue added during .the rolling by the numeral 25. As illustrated in Figure 4, which is an enlargement of that portion of Figure 3 inside the dot-dash line 26, applicant-.hasattempted .to show that theglue added during the rolling process is much more deeply pressed .into the surface.abrasivegrains in the groove, that is at .28, than it isin thebalance of the roll as.at.30. Figure 4- indicates that .the'abrasive grain at the .firstilayer belowlthe -outside tlayer .of the roll is thoroughly embedded .in or flooded by the glue .layer 25; whereasat the point 30, representing.theabalance .of the roll, the .glue layeris justtouchingihe tipsof theabrasive grains.
The result'is that in the crosssection.of-theroll shown in Figure 3, one .has -at :the groove 19 a substantially continuous glue seal from the outer surface to the core. This provides the requisite strength without using a quantity of glue such that it will flood the abrasive grains throughout the rest of the roll.
Continuing to refer to Figure 4, the surface 32 does not engage the work at a time when it is still attached to the balance of its layer. The surface 32 does not get hot by engagement with the work but only by heat conduction from points 30 and 31. Hence the glue at 28 does not become so hot. Ultimately, the roll will wear down to the surface 32, but by that time the layer to which the surface 32 was attached will have been worn away and the glue at 23 no longer has a holding function. The next layer below the groove will perform the holding function. Applicant points out that for explanatory purposes the depth of the groove in Figure 4 is exaggerated with respect to the thickness of the layers. The showing in Figure 3 is more accurate.
Referring to Figure 5, applicant has made some rolls wherein there are a plurality of depressions 34- in the abrasive grain surface. These depressions should only be made where glue has been added as a binder. The roll shown in Figure is, therefore, one glued throughout its entire length. A cross section along the line a-a of one of these depressions would look substantially like the cross section shown in Figures 3 and 4 of the groove excepting they would be closed as suggested by the dotted line 35.
In Figure 6, applicant shows a roll having a groove 36 at one end and a groove 38 at the other, each spaced from the end by about one-quarter inch. The purpose of the groove at each end is to improve the holding, particularly for the longer rolls.
In Figure 7, applicant shows a preferred form of roll which is useful particularly for lengths up to one and onehalf inches and longer. This roll includes one groove 40 spaced from the end by about one-quarter inch, and it has a circumferential roll of round indentations or depressions 42 between the groove 40 and the end 44. This roll may be glued along the lines 46 and 43. Tests on this roll have shown it possesses high abrasive qualities in the area from the line 46 to the end 50, while at the same time it does not come apart during the hardest usage.
As for applicants method of forming the roll, refer ring to Figure 8, the roller 52 is made of steel while the roller 54 is made of comparatively soft rubber, by which applicant means one can press it inwardly under thumb pressure. Mounted on the near side of the roller 54 in the same shaft 58 is a metallic disk 56 whose circumference coincides with the uncompressed circumference of the rubber roll 54. Spaced slightly from said disk 56 is a star wheel 60, also on the same shaft 58. The apex 62 of each star is rounded so that it will not perforate the emery cloth. The cloth 63 is sprayed with glue 64 and rolled as shown between the rubber roll 54 and the steel roll 52 which are pressed together by springs. As the roll 66 enlarges, the shafts 58 and 68 spread apart. The rubber roll is deformed at the points of engagement with the forming roll 66, the points being indicated by the arrows 70. The steel disk 56, however, is as sturdy as the steel roll 52, and consequently the disk 56 rolls a groove into the forming roll 66. For the same reason, the star wheel 60 inserts the indentations 42.
With respect to these indentations 42, applicant invites attention to the fact that those in different layers are not in radial alignment. The spacing of the apices 62 on the star wheel is constant, but the diameter of the roller is steadily increasing. While one might work out a roll and a mandrel which could place the indentations in alignment for one weight of emery cloth, it would be too much trouble to do this for all weights. These rolls differ from each other not only in diameter and length, but in the thicknes of the cloth and the grain size. 'This means that a one and one-half inch roll having a threequarter inch diameter made with a very fine grain emery cloth will have many more layers than one made with a very heavy grain emery cloth.
A roll can be made employing just the star wheel 60 omitting the disk 56.
In making the roll illustrated in Figure 5, a plurality of star wheels would be used, but they would have a smaller number of apices than that shown in Figure 8 and they would be well spaced.
While the invention is shown solely in connection with cylindrical rolls, it will be useful for conical rolls or any roll wherein a strip of emery cloth or some other strip material such as paper carries an abrasive on at least one surface and is wound around an axis so as to have a spiral cross section. There are conical rolls formed by stepping back the layers of material at one end. All such rolls must work from a spinning shaft and applicants groove or indentations are found in that end of the roll which is to be adjacent to the drive element, usually the end of a flexible shaft.
Having thus described applicants invention, what he claims is:
1. An abrasive roll comprising a strip of cloth having an abrasive surface spirally wound in layers around an axis with the abrasive surface outermost, a groove in the abrasive surface of the strip extending inwardly substantially to the core, and glue on the under side of the groove.
2. An abrasive roll comprising a strip of cloth having an abrasive surface spirally wound in layers around an axis with the abrasive surface outermost, a groove in the abrasive surface of the strip extending inwardly substantially to the core and lying in a plane at right angles to the axis of the roll, and glue on the under side of the groove.
3. An abrasive roll comprising a strip of cloth having an abrasive surface spirally wound in layers around an axis with the abrasive surface outermost, a groove in the abrasive surface of the strip extending inwardly substantially to the core and lying in a plane at right angles to the axis of the roll, a row of spaced depressions in the abrasive surface of the strip parallel to the groove, and glue on the under side of the groove and depressions.
4. The method of making an abrasive roll which comprises the steps of applying an adhesive to the smooth surface of an abrasive-bearing cloth, of then rolling the cloth with the abrasive outermost around an axis into a spiral, and of pressing indentations into the curved abrasive surface as the roll is being formed.
5. The method of making an abrasive roll which comprises the steps of applying an adhesive to the smooth surface of an abrasive-bearing cloth, of then rolling the cloth with the abrasive outermost around an axis into a spiral, and of pressing an inwardly directed groove into the curved abrasive surface as the row is being formed so that the groove will continuously lie in a plane substantially at right angles to the axis of the forming roll.
6. An abrasive roll comprising a plurality of abutting layers of abrasive-surfaced cloth positioned around a common axis, a groove in the outer surface of each layer, said grooves lying in a plane at right angles to the axis, and glue on the under side of the grooves.
References Cited in the file of this patent UNITED STATES PATENTS 736,114 Koenig Aug. 11, 1903 1,119,760 Koontz Dec. 1, 1914 1,952,385 Morlock Mar. 27, 1934 2,290,098 Field July 14, 1942 2,358,724 Manchester Sept. 19, 1944