US 3643045 A
Described herein is an improvement in a grinding machine to reduce overgrinding of the surface of a workpiece in the area at the end of each stroke of a reciprocating grinder which comprises counterreciprocating means and means to limit the forward movement of the reciprocating grinder.
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Description (OCR text may contain errors)
United States Patent n51 3,643,045
Beck [451 Feb. 15, 1972  RECIPRQCATING GRINDERS  References Cited  Inventor: Herbert P. Beck, Honey Brook, Pa. UNITED STATES PATENTS 1 Assisnee: Allegheny Ludlum Steel mm 3,461,926 8/1969 Larson ..144/3 x Brackenridge, Pa.
22 F] d: A 70 Primary Examiner-Hennan J. Hohauser l In 1 l9 Attorney-Richard A.- Speer, Vincent 6. Gioia and James A.  Appl. No.: 31,457 Bemeburg Related US. Data 57 ABSTRACT  Division 734,008 June Deseribed herein is an improvement in a grinding machine to reduce overgrinding of the surface of a workpiece in the area  U.S.Cl. ..200/47 at the end of each awoke of a reciprocaflng grinder which  21/28 comprises counterreciprocating means and means to limit the 58] Field at Search 144/3; 200/47, 153. [226(1) 1492, f d movement ofthe reciprocating gfinden 1cm, 2 Drawing Figures RECIPROC-ATING GRINDERS This application is a division of copending application Ser. No. 734,008 filed June 3, 1968.
BACKGROUND OF THE INVENTION In the normal processing ofcertain types of stainless steels and other alloy steels, it is necessary to grind the surface of a hot-rolled plate to smooth the surface to prevent surface defects from manifesting themselves during subsequent operations and spoiling the finished surface of the material. The grinding operation can be performed by hand, ut it is preferably performed by a grinding machine of the type edge of the workpiece. The workpiece is preferably positioned on the workpiece support means so that at the extreme limit of movement of the means supporting one of the grinding wheels, that grinding wheel extends just to one of the lateral edges of the workpiece. When the grinders are started, the air cylinder is activated which causes the grinder to reciprocate across the plate to be ground. Simultaneously; a low-speed gearhead motor is started to move the gantry slowly along the tracks. The distance the grinders reciprocate is at-least equal to the distance between the grinding wheels so that the entire surface of 'the workpiece will be covered as the grinders reciprocate and as the gantry moves. A conventional solenoid valve is used to control the length of the stroke of the air cylinder and consequently the length of the stroke of the grinders. On grinding machines of the type described in the aforementioned patent, the solenoid valve which affects the reversal of the reciprocating grinders is energized by an electromechanical control device, i.e., limit switch. However, since the limit switch is in a fixed position, the reversal of the grinders movement occurs at the same place (dwell point) each time. This causes overgrinding atthe dwell point dueto the fact that the grinders forward motion must decelerate, go through zero speed at reversal, and accelerate in the opposite direction. The present invention eliminates overgrinding along a fixed line by spreading the swell point over a greater area.
This is accomplished by activating an electromechanical control device which causes reversal of the reciprocatinggrinders at a different point each time.
SUMMARY OF THE INVENTION The present invention, used in combination with a reciprocating ;grinder, causes reversal of the stroke of the reciprocating means, to which the grinder is connected, at random points within a defined distance and thus prevents overgrinding. In general, this can be accomplished by activating an electromechanical control device to cause reversal of the stroke, i.e., distance traversed, of the reciprocatinggrin- BRIEF DESCRIPTIONOF DRAWINGS FIG. I, is a front elevationof a grinding machine of the type described in U.S. Pat. No. 3,300,906 in combination with a specific embodiment of this invention.
FIG. 2, is an elevation of anenlarged portion of FIG. I.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, aspecific embodiment of this invention includes a gantry designated generally as 10. The gantry 10 includes a center span 12 supported at its opposite ends by a pair of support towers or legs 14 and 16. The support towers l4 and 16 are provided with flanged wheels l8 which are mounted on tracks 20 so that the gantry is movable therealong. The wheels 18 are drivenby suitable drive means (not shown) which are connected to the wheels through chain and sprocket system 24.
The gantry l0 spans a workpiece-supporting bed 25 which is provided with a plurality of skids (not shown) upon which the workpiece, 25A, e.g., plate to be ground is supported.
The center span 12 of the gantry includes an I-beam frame member 28 which supports a pair of tracks,29. A trolley 30'is mounted on the tracks 29 by means of upper flanged wheels and lower guide wheels (not shown). An air cylinder 33 is mounted on the I-beam frame member 28 and its piston rod 33A is connected to a trolley 30 by abracket 34 which is bolted to the-trolley 30. The air cylinder 33.is connected to a source of compressed air (not shown) win a conventional manner to drive the piston rod and, hence, the trolley 30 reciprocally. on the tracks29.
A plurality of support brackets 35 are secured to the underside of the trolley 30 at regular intervals, and wrist pins 36 pivotally mount grinder support arms 38 to each of the brackets 35.
Grinders 40, each having a conventional grinding wheel 41, are pivotally mounted to the end of each support arm 38. The support arms 38 are adapted to be oscillated in avertical plane by means of another air cylinder 44. The air cylinder 44 is trunnion mounted on a bracket which is bolted to the trolley 30.
Referring now to FIG. 2, a limit switch 10] mounted on trolley 30, is operatively connected to air cylinder 33 to control the distance the piston rod 33A travelsaway from the air cylinder 33.
Another air cylinder 102, connected to a source of air (not shown), is mounted on'the- I-beam frame, 28 and its-piston rod 102A has adjustably mounted to it a bracketl03 which functions as a limit switch trip. Air cylinderl02, reciprocates the limit switch trip 103 over a distancesufficient to engage the limit switch 101 after the trolley' 30'has traveled at least the distance equal to the distance between grinders. It is the function of the limit switch trip 103'toengage the limit switch 1,01 and cause reversal of the trolley 30. Since both the limit switch 101 and limit switch trip 103 are reciprocating, actuation of the limit switch 101 .will occur at a random point along the overlap of the stroke of the pistons, 33A-and 102A.
The air cylinder 102 is the. preferred means for activating the limit switch 101. A fewexamples of some other means for causing reversal of the air cylinder, 33 are; motor and screw; motor and cam; motor, rod and pinion; and, a hydraulic cylinder.
It is preferred that the piston rod 102A of cylinder I02- reciprocate at .a slower rate than that at which piston: rod 33A reciprocates, and that such rate-be less than one-fourth of that of the aircylinder piston 33A. This permits the dwell point to be spread over a greater distance because the probability of the limit switch being tripped is spreadiover'a longer time interval.
To assure tripping of the limitswitch 101 by the limit switch trip 103, thestroke of the piston'rods from each cylinder must overlap. It is preferable that thedistance along which the limit switch trip 103 can and must stroke the limit switch 101, after it has traveled at least a distance equal to the distance between grinders, be 10 inches. This prevents overgrinding by randomly spreading the dwell point over a distance of 10 inches.
Although the invention has been shownin combinationwith certain specific embodiments, it will be'readily apparent to those skilled in the art that various changes in form and arcomprising: means separate and apart from said reciprocating apparatus to continually vary the location of said limit switch trip within a predetermined distance and along a path of travel extending parallel to the path of travel of the reciprocating apparatus so as to continually vary the length of the stroke of said first reciprocating means.