US 3130621 A
Description (OCR text may contain errors)
April 28, 1964 c, ELSE 3,130,621
ORBITING METAL CUTTER Filed NOV- 17, 1961 INVENTOR. HARRY C. ELSE United States Patent Ofiice 3,139,621 Patented Apr. 28, 1964 3,139,621 QRBITENG METAL CUTTER Harry C. Else, 1921 Forbes St, kittshnrgh 19, Pa. Filed Nov. 17, 1961, Ser. No. 153,084 Claims. (Cl. 83-471) This invention relates to apparatus for cutting metal, and more particularly to metal cutters that utilize rotating cutting wheels, such as abrasive wheels or circular saws.
Heretofore, the cutting operation has been a slow one and often unsatisfactory. If a large piece of metal is being cut, it is difiicult to keep the cut straight because the wheel tends to run off to one side or the other. Although the wheel and metal usually are water cooled, they still run very hot and the life of the wheel is short.
It is among the objects of this invention to provide a metal cutter which can cut metal very much faster than any apparatus of a comparable nature known heretofore, which always cuts in a straigth line, which does not overheat, and in which the cutting wheel has a long life.
In accordance with this invention, an inclined arm behind a worktable extends from below the level of the table top forward and upward to a point above that .level. The lower end of the arm is supported by rotatable eccentric means for rotating the lower end of the arm in a vertical plane. The upper end of the arm rotatably supports a vertical circular cutting wheel beside it. The wheel is driven at high speed, such as by a motor mounted on the lower end of the arm. Extending forward and backward across the upper part of the arm there is a lever, the rear end of which is pivotally supported on a transverse axis. Means pivotally connects the central part of the lever with the upper part of the arm on a transverse axis also. This last-mentioned means is movable forward and backward as the eccentric means is rotated. When the front of the lever is lowered to press the cutting wheel down against the rear end of a workpiece on the table, the wheel is moved back and forth by the upper end of the arm as the wheel moves downward and forward through the workpiece. I
The prefered embodiment of the invention is illustrated in the accompanying drawings, in which:
FIG. 1 is a side view of my apparatus;
FIG. 2 is a fragmentary front View thereof, partly broken away in section; and
FIG. 3 is a fragmentary section of the eccentric drive, taken on the line III-J11 of FIG. 1.
Referring to FIG. 1 of the drawings, a work table has a top 1 supported in any suitable manner above a watercollecting tray 2. An angle bar 3 is rigidly mounted on the back of the table top, and suitable clamping means 4 are mounted on the front part for holding a metal workpiece 5 on the table while it is being cut.
Extending backward from the table is a low frame 7, on the rear part of which a pair of aligned bearings 8 are mounted. A shaft 9 extends across the frame and is jonrnaled at its ends in the bearings. As shown in FIG. 3, near each end the shaft is provided with an integral eccentric 11, which rotates in a bearing 12 that may be rigidly mounted in the end of a metal channel 13 or other suitable cross bar. Mounted on one projecting end of the shaft is a sprocket 14 that is driven by a chain 15 from a variable speed motor-driven gear-reduction unit 15 also mounted on the frame. The throw of the eccentric is not critical, but good results have been obtained when the eccentric is only about one-quarter inch ofi-center, making about a half inch throw.
The rear end of a heavy arm 18 is secured to channel 13 below the level of the table top and is inclined forward and upward to a point above the level of the table. This arm has a crosshead 19 at its upper end projecting from opposite sides of the arm. A horizontal shaft 20 is journaled in the crosshead and has a vertical circular cutter 21 rigidly mounted on one end. The cutter may be a 'saw or an abrasive wheel, preferably the latter. Pulleys 22 are keyed on the opposite end of the shaft and are driven at high speed by belts 23 from an electric motor 24 at the lower end of the arm. The motor is mounted on a base 25 that is supported by the arm at an oblique angle. Preferably, the base projects behind the arm far enough for the weight of the motor to overbalance the cutting Wheel and attempt to swing it upward.
To swing arm 18 downward in order to press the rotating cutting wheel against the workpiece, a lever 27 is used. The lever extends forward and backward across the upper part of the arm, and the rear end of the lever is pivotally supported on a transverse axis. One way of accomplishing this is to mount the lever on a pin 28 extending laterally from the upper end of a link 29, the lower end of which is connected by a pivot pin 30 to a bracket 31 supported by the table legs. The link extends down beside the central portion of the arm and then is bent to extend forward to the bracket.
The central part of the lever is pivotally connected to the upper part of the arm on a transverse axis also. This can be done in various ways, such as by mounting a sleeve 33 on the lever and pivoting it in the upper end of a bracket 34 projecting upward from the upper end of the arm. The sleeve may be provided with a set screw 35 so that it can be adjusted along the lever.
A preferred way of limiting the distance that the cutting wheel can be tilted up and down is by means of a rod 37 above the arm. The lower end of the rod is pivotally mounted in a bracket 38 on the arm. A sleeve 39 is slidably mounted on the arm and has a forwardly extending lug 40 that projects into a fork on the rear end of the lever and is mounted on pivot pin 28. As the front end of the lever is pulled down or allowed to rise, sleeve 39 will slide up and down the rod. The distance that it can move is limited by collars 41 and 42 adjustable along the rod and serving as upper and lower stops.
When it is desired to cut a block of metal clamped on the table, the front end of the lever is pulled or forced down to press the rotating cutting wheel against the upper rear corner of the workpiece above a slot in angle bar 3 and in the table top below the workpiece. As pressure is applied downward on the cutting wheel, the orbiting lower end of the arm causes the upper end to travel back and forth, carrying the wheel with it. For fastest cutting the eccentrics 11 are rotated so "rapidly that the wheel tends to be moved forward faster than it can cut, with the result that it tends to ride up in the cut. For best results, the eccentrics should turn at at least r.p.m. This causes the wheel on the forward stroke to cut more deeply in the upper portion of the out than in its lower portion. On the other hand, when the wheel starts its backward stroke, it pulls away from the base of the upper end of the cut and cuts progressively deeper toward the lower end. Consequently, as nearly as the cutting operation can be observed, the wheel cuts into the workpiece alternately at the upper and lower portions of the kerf, with the result that the pressure of the wheel against the metal is concentrated in a relatively short are at any given moment, and rapid cutting occurs. Furthermore, as the point of greatest pressure moves back and forth from one end of the cut to the other, the area of the metal that is at highest temperature continually shifts likewise, so the workpiece does not become so hot as it would if the cutting wheel remained in tight contact with the base of the cut throughout its length. Another advantage is that less total pressure has to be applied to the wheel to make it cut because it cuts only a small area of the workpiece at any given moment, whereby the wheel is not deformed and therefore does not lead to one side or the other of the cut.
Every time the cutting wheel begins to move backward to pull away from the base of the upper end of the cut, a gap is formed, into which cooling water under pressure can be sprayed to flush out the cuttings and loose grit. This materially increases the cutting rate. For example, a block of metal that requires about fifteen minutes to be cut by a chop stroke cutting wheel can be severed with my cutter in less than a tenth of that time. The cutter cannot form a sump in the work, where abrasive and metal cuttings could accumulate and cause the wheel to bind. Also, the workpiece remains so cool that it does not expand and pinch the cutting wheel, which would increase the friction and heat and interfere with replacing a worn wheel. Since there is no binding of the cutting wheel in the workpiece, the face of the wheel wears straight or square, which is another reason why the wheel does not lead to either side. The life of the wheel also increases materially. Due to the fact that the wheel cuts so fast and so easily, no power feed is required and yet operator fatigue is negligible.
For some reason that is not yet understood, this cutter performs a great deal better if eccentrics 11 are rotated clockwise as viewed in FIG. 1, rather than counterclockwise. Orbiting of the lower end of arm 18 tends to cause its upper end to orbit also, but in the opposite direction, apparently due to the inertia of the upper end. Downward pressure on handle 27 to hold the wheel against the work partly or nearly completely restrains orbiting of the wheel, depending on the pressure exerted, but the tendency is there nevertheless and may have something to do with the speed at which the wheel cuts. It is surmised that if the eccentrics were rotated in the opposite direction, the cutting wheel would tend to gouge the material on the forward stroke, thereby greatly increasing the stress on the wheel which would increase the heat and tend to lead the wheel to one side.
Generally, when the arm is in its lowest position, it should still make an angle with the table of at least about 30 degrees. When the workpiece has been cut through and lever 27 is released, the motor will swing the wheel back up to its original raised position. It will be found that no burrs are left at top or bottom of the workpiece.
The invention disclosed herein can also be used for cutting or grinding a long plate or the like. In such a case, the cutting wheel or grinding wheel and the related parts of the apparatus are suspended from a carriage above the work, and the carriage is moved from one end of the work to the other as the wheel is pressed down against it. A big advantage of such a machine is that it can cut straight through the work without first having to make a scoring cut to guide the cutting wheel. By using a reversible motor to drive the eccentrics, a heavy plate can be cut in either direction equally effectively.
In accordance with the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.
lower end of the arm in a vertical plane, a vertical circular cutting wheel beside the upper end of the arm and rotatably mounted thereon above said table top level, means supported by the arm for rotating the wheel at high speed, a lever extending forward and backward across the upper part of the arm, means pivotally supporting the rear end of the lever on a transverse axis, and means pivotally connecting the central part of the lever with the upper part of the arm on a transverse axis, said lastmentioned means being movable forward and backward as said eccentric means is rotated, whereby when the front end of the lever is lowered to press said wheel down against the rear end of a workpiece on the table the wheel is moved back and forth by the upper end of the arm as the wheel cuts downward and forward through the workpiece.
2. A metal cutter according to claim 1, in which the speed of said eccentric driving means is great enough to cause the arm to pull the wheel away from the base of the upper end of the cut at the beginning of each backward movement of the wheel. a
3. A metal cutter according to claim 1, in which said arm is inclined downward and rearward from said table at an angle of at least about 30 when the arm is in its lowermost cutting position.
4. A metal cutter according to claim 1, in which said eccentric means is rotated in a clockwise direction when viewed from the side of the machine in which the eccentric means is at the right-hand end of the arm.
5. A metal cutter comprising a work support, means for holding a workpiece thereon, an arm inclined in a vertical plane adjacent said support, rotatable eccentric means secured to and supporting the end of the arm remote from said work support on a transverse axis, means for driving said eccentric means to move said end of the arm in a circular path in a vertical plane, a vertical circular cutting wheel beside the opposite end of the arm and rotatably mounted on it on an axis parallel to said transverse axis, and means supported by the arm for rotating the wheel at high speed, said opposite end of the arm being movable downward for pressing said wheel against a workpiece on the work support to cut the workpiece.
References Cited in the file of this patent UNITED STATES PATENTS 1,569,186 Hilke Jan. 12, 1926 1,640,517 Procknow Aug. 30, 1927 2,872,955 Schmitz Feb. 10, 1959 2,996,088 Hensley Aug. 15, 1961 3,046,707 Obear July 31, 1962 3,053,018 Tracy Sept. 11, 1962 FOREIGN PATENTS 1,023,947 Germany Feb. 6, 1958