US2815619A - Grinding machine - Google Patents

Description

Dec. 10, 1957 T. L. BROWNLEY GRINDING MACHINE 3 Sheets-Sheet 1 Filed NOV. 14, 1952 mw N I *m M m z AwHn M F W .u H H -J fi m NM n w w ATTORNEY Dec. 10, 1957 'r. L. BROWNLEY GRINDING MACHINE 3 Sheets-Sheet 2 Filed Nov. 14, 1952 MN KW o INVENTOR TRENHOLM LBROWNLEY ATTORNEY Dec. 10, 1957 T. L. BROWNLEY 2,815,619

GRINDING MACHINE Filed Nov. 14, 1952 5 Sheets-Sheet 3 INVENTOR TRENHOLM LBROWNLEY BY Mam ATTORNEY 2,815,619 GRINDING MACHINE Application November 14, 1952, Serial No. 320,569 3 Claims. (Cl. 51-247) This invention relates to grinding machines and more particularly to automatic means for sharpening helical knives. Helical knife blades, such as those employed in the cutting of filaments into staple as disclosed in the application'of Donald R. Hull, Serial No. 304,712, filed August '16, 1952, now Patent No. 2,694,447, dated November 16, 1954, and assigned to the assignee of the present application, have in the past been sharpened by hand operations which were laborious, time-consuming, and 'inefiicient. A slip in the operation by a careless, inept or inattentive operator would much prolong the duration of grinding necessary to produce the desired edge, especially when attempting to speed up the operation by use of a hand-held, motor-driven grinding wheel. Not only would a slip by the operator cause damage to the helical knife blade, but might well result in injury to the man.

It is an object of this invention to provide a grinding machine which can beset up to sharpen a helical knife blade automatically. A further object of this invention is to provide an apparatus which can be adjusted to sharpen automatically any helical knife blade irrespective of diameter, helix angle or number of turns. Other objects. will become apparent from the specification and claims.

The objects of this invention areaccomplished by a grinding machine which, in general, includes a work support on which the helical knife is turned (as when cutting) while the cutting edge is being ground and a motor-driven grinder mounted to provide for a multiplicity'of adjustments and movements which enable the grinder to follow the spiral of the knife edge as the knife is turned. The mounting includes means actuated by the knife itself for automatically maintaining the grinder in proper position as the knife is turned regardless of the envelope or longitudinal outline of the knife extremities and the bevel to which the edge is ground.

In the drawings, which illustrate ments of the invention,

Figure 1 is aplan view of my improved sharpening device,

Figure 2 is an elevation thereof,

Figure 3 is a longitudinal vertical section of the grinding wheel carriage taken on line 3-3 of Figure 1,

Figure 4 is a fragmentary detail of an alternative means of moving the carriage,

Figure 5 is a detailed elevation on an enlarged scale of the grinding wheel and immediately associated mechamsms,

Figure 6 is a detail of a means for dressing the grinding wheel,

Figure 7 is an end view showing a honing attachment, and

Figure 8 is a plan view of Figure 7.

Referring now to Figures 1 and 2, it is seen that this particular exemplification of the invention comprises a supporting platform 11 on which is mounted the work preferred embodifitea ed Dec 1 257 2 a support 12 for holding the helical knife blade 13 mounted for frotation'on axle 14. The knife has threecomplete turnsof constantly increasing radius and constant pitch; the envelope of the edge extremities is conoidal, and the longitudinal outline accordingly is V-shaped. Traverse bed plate 15 is likewise suitably mounted on plat form 11 by means of threaded shafts 16. Handle 17 ..is affixed to one bevel gear of the pair in each of systems 18, the other bevel gear of each system being aflixed to one of threaded shafts which locate the traverse plate perpendicularly with respect to the axis of the work support. I I

The apparatus likewise comprises a swivel table 19 mounted adjustably about axis 21. Gear section 20 is anintegral part of the table 19, and is designed to co; operate with worm 23 for setting the swivel table at any required angle with respect the work. Nut 25 may be tightened to lock the table in the desired positionlf 'j The grinding Wheel carriage 32 is mounted on swivel table 19 by means of two parallel rods 34 running along the length of the table, and is urged toward the work by loading weight 27 on cable 28 running over pulley 29 (Figure 3). Alternatively a spring 71 (Figure 4) may replace the system of weight, cable and pulley, but the pull is not as uniform. The mounting rods shown are straight to accommodate the V-shaped outline of the illustrated helical knife. However, where the outline of the blades is not straight but is concave or convex, these rods are made to conform to that contour to give the desired operation of the sharpening device.

The grinding wheel assembly is mounted on table 30 which is adjustable about axis 31 on carriage 32 by means of worm wheel 33 and gear section 35 cut into the periphery of grinding wheel table 30. Nut 26 may be tightened to lock this table in position.

The manner of mounting the grinding wheel assembly is core clearly shown in Figure 5. The grinding wheel 36 is mounted on spindle 37 which is driven through a convenient belt and pulleysystem 38 (or a gear system, if desired) by motor 39 (Figure l). The spindle 37 is journaled in housing 40 which in turn floats on rods 41. A constant bearing pressure of the grinding wheel 36 against the helical knife is obtained by the pressure of springs 46 on rods 41 urging the floating spindle housing toward the knife blade. Nuts 47 may be used to adjust the grinding wheel pressure by compressing the springs. In addition, the grinding wheel carriage assembly carries a positioning unit, such astwo fingers 51, which are adapted to bear against the side of the helical knife blade as it rotates and automatically adjust the position of the grinding wheel carriage, so that it will follow the contour of the cutting edge of the helical knife blade and maintain a uniform position relative to the portion of the blade being ground. These fingers are adjustable, both individually and as a unit. The individual adjustment is accomplished with the aid of set screws 50 in the finger holders and may be used when it is desired to have both fingers exert equal pressure on the blade surface. The unit adjustment is accomplished by means of a Vernier operated by hand wheel 52 which permits adjustments to be made on grinding wheel pressure at any time as desired.

For the tool steels normally employed in staple cutting knives it has been found that a grinding wheel made of grit silicon carbide with a soft vitreous bond is preferred for a rotational speed of 900 revolutions per minute. For convenience a 3" diameter cup-shaped grinding wheel is used. In some instances it may be desirable to mount a spring loaded honing stone 55, as shown in Figure 8, to bear on the opposite side of the knife edge below the grinding wheel. The honing stone 3 takes off or stands up the wire edge which the grinding wfieropm.

In actual operation the helical knife 13, mounted on axle 14 held in support 12, is affixed through a suitable arrangement of .bol't'sfto'platforiii' 11 as shown in Figure 1'. 'Swivel' table'19'is'next revolvedabout axis 211 meanso'f warm 23 and gear 'se'cuaa Ztl so that polished rods 34ers para llel to the orie side of the longitudinal outline formedbfth'e edge extremities (i1 eL, .tan'g'ential to" rotational envelope) ofthe knife blade. .The distance of tr verse'bed plate rsrrqmiw'ark support 12 is then adjustedhn plafforht '11"b'y turning handle 17 until grinning Wheel 36'is 'infjuxtaposition with helical knife blade 13. -The angleht which grindingwheel'36 b ars against helical knife 13 is next adjusted (to'control the bevel of the grind on the knife) by rotating worm 33 which in turnrfevblve's the grindingwheel table 30 about axis SIbY'rrieanS of gear section 35. A further adjustme t bf traverse 'platelS maybe necessary after selection 9 i'thedesire'd cutting bevel. Once these adjustments'have been jinade, lock nuts 25'and 26 are tightened down to secure the assembly in operating position. Next, the positioning'or follower fingers 51 are adjusted by means of hand wheel 52 to obtain the desired position of the grinding wheel carriage relative to the knife blade 13.

Manual means or amotor 57 may be used to rotate the helical knife blade at a slow speed, such as 4 revolutions per minute, which is determined by inertia considerations and by sharpening considerations. Where the helical knife blade is composed of but a single turn or less, niicroswitch elements 58 actuated by cam 59 may be used to reverse the rotational direction of the motor each 360", or whatever length of arc the knife may cover. As shown most clearly in Figure 1, when the motor rotates so as to advance the helix of the blade, the

fingers 51 cause the grinding wheel carriage assembly to advance with the knife blade. Then, when the motor reverses so as to cause the helix to retreat, the weight 27 on cable 28 causes the fingers 51 to maintain positive pressure against the helical knife blade so that the grinding wheel carriage assembly retreats with the retreat of the helix.

An additional feature of the apparatus shown in Figures 5 and 6 is a grinding wheel dressing attachment. This consists of arm 61 for holding Vernier 62 by which means diamond 63 is advanced across the face of the grinding wheel to true the surface. The position of the diamond may be adjusted through the screw and lock nut arrangement 64. Alternatively, as shown inFigure 6 this grinding wheel dressing device may be of the quickacting lever arm type with the diamond holder screwed into hole 65. An alternative type of finger is also shown in Figure 6 consisting of ball bearing wheels 72 mounted on the ends of rods. These wheels make rolling contact with the side of helical knife 13 to eliminate wear.

Since many different embodiments of the invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited by the specific illustrations except to the extent defined in the following claims.

What is'claimed isz' lfA grinding machine for sharpening helical knives comprising means for supporting and rotating a helical knife'about the helix axis, a grinding wheel for sharpening the knife, a spindle'mounting said wheel, a carriage supporting said spindle for rotation and axial movement, means for rotating said spindle, means for controlling axial movement 'of said spindle to maintain a constant pressure between said wheel and the knife during grind- 'ingffrieaiis" for adj iistingtheangular position of said spindle on said carriage to vary the angle of bevel ground on the knife edge, a supporting table for said carriage, means mounted on said table for mounting said carriage movably along a fixed path onsaid table, means mounted on said carriage and adapted to bear against the side of the knife, means mounted on said table for urging said carriage toward one end of the path to bring the grinding wheel against the knife, means for adjusting the angular position of said table to bring said carriage path parallel to one side of the outline of the edge extremities of the helical knife, and means for adjusting the distance of said table from said knife to bring the grinding wheel into juxtaposition with the knife edge.

2. A grinding machine for sharpening helical knives comprising a supporting platform, a work support on said platform for holding the axle of a helical knife for rotation of the knife during sharpening with the axle horiiontal and parallel to one side of the platform, means for rotating the knife, a traverse bed plate mounted on platform adjacent to said work support, traversing means 'for adjueting said plate toward and away from saidwork supportga swivel table adjustably mounted on said traverse plate for rotation to a desired anglular panting; aftralversing carriage mounted for movement along ajfixed path on said swivel table, a grinding wheel table adjustably mounted on said carriage for rotation toa'd'esired angular position, a positioning unit carried by said grinding 'wheel table and arranged to rest against one fsideof the knife blade to arrest further movement of said carriage in that direction, loading means for urging said carriage toward the knife blade to maintain said un it contact with the blade, a grinding wheel spindle supported for rotational and axial movement on said grinding wheel table, a grinding wheel mounted on said spindle, driving means for rotating said spindle, and pressure means for urging said spindle in an axial direction toward the knife blade to maintain said grindingwheel in contact with the blade at the desired grinding pressure.

3. A grinding machine for sharpening a helical knife, comprising means for supporting and rotating a helical knife about its helix axis; a rotatable grinder for sharpening the knife; and movable mounting means for supporting the grinder, including means actuated by contact with the knife. for automatically maintaining the grinder'in sharpening position, a bed plate screw-adjustableperpendieular to the helix axis, a swivel table carried on. the bed plate and screw -adjustable about an axis perpendicular to both the bed plate and the helix axis and rec ipr ocable along a path parallel to the edge outline .Of the knife, a housing carried on the swivel table and screwadjustable about an axis parallel to the axis of the swivel table, and a spindle rotatably bearinged on the housing and reeipr oeable along a path parallel to edge bevel of the knife.

References Cited in the file of this patent UNITED STATES PATENTS 1,077,333 Du Brul Nov. 4, 1913 1,085,876. Redden Feb. 3, 1914 1,566,614 Madsen Q Dee. 22, 1925 2,9, 9,09, 7. Rpot, Jan.- 26, 1937 2,377,126,. Brown May 29, 1945 2,530,479 Pater et al. Nov. 21, 1950 2,591,648 Lucas May 20, 1952

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