US2273456A - Machine for grinding thin metal strips - Google Patents

Description

Feb. 17, 1942.

H. L. ZIMMERMAN MACHINE FOR GRINDING THIN METAL STRIPS Filed May 6, 1939 2 Sheets-Sheet l INVENTGR 7- E HENRY L. ZlMM-ERMAN Z ATTOIZI EM H. L. ZIMMERMAN MACHINE FOR GRINDING THIN METAL STRIPS Feb. 17, 1942.;

2 Sheets-Sheev-Z Filed May 6, 1939 :IIIIIII INVENTOR HENRY L. ZIMMERMAN BZ ATTORN Patented Feb. 17, 1942 UNITED STATES PATENT OFFICE MACHINE FOR GRINDING THIN METAL STRIPS Henry L. Zimmerman, Davenport, Iowa Application May 6, 1939, Serial No. 272,263

11 Claims.

This invention relates to grinding machines, and in particular to machines of the type used to produce cutter blades, such as, for example,

readily accommodate blades having considerable variance in width. A more specific object is to provide a grinding machine which may be readily adjusted to accommodate blades of varying width without making any adjustment of the grinding wheel.

Another object is to provide a grinding machine which is provided with simple adjustments for accommodating cutter blades having differing angles of cut or having varying configurations of the cutting edges.

7 Generally the grinding wheels of present day blade grinding machines have a vertical and horizontal adjustment to move th wheel closer to the work as the grinding wheel diameter decreases due to wear. Since, however, the usual practice is to have the blade contact the grinding machine at a point below the'axis thereof, two adjustments of the grinding wheel are necessary to moveit closer to the work when the grinding wheel diameter has decreased. Another difficulty encountered in the operation of the present day machines is the adjustment for changing the angle of out which determines the angle between the cutting edges of the blade. It usually requires a vertical and a horizontal movement of the grinding Wheel and motor and it may be difficult to obtain the identical setting once it has been disturbed.

A rather specific object of the present invention i to produce a grinding machine .in which grinding wheels of reduced diameter may be moved into contact with the work by a single, relatively simple adjustment.

A further object is to provide a blade grinding machine in which the angl of cut may be readily changed as desired and may be easily reproduced at any time.

Another object is to provide a grinding machine of the type mentioned which is simple in design and construction and relatively inexpensive to manufacture.

Other objects and advantages of the present invention will become apparent from the following detailed description accompanied by the drawings, in which:

Figure 1 is a plan view of a grinding machine embodying the present invention;

Fig. 2 is a sectional view in elevation taken substantially on the line 2- 2'of Fig. 1, illustrating details of the machine Fig. .3 is an enlarged plan view of the blade holding mechanism for use in the machine shown in Fig. 1;

Fig. 4 is an elevational sectional view taken substantially on the line 4--4 of Fig. 3, showing how the blade holding mechanism may be mounted;

Fig. 5 is a fragmentary sectional view in elevation taken substantially on the line 5-5 of Fig. 3;

Fig. 6 is a fragmentary plan view taken substantially on the line 6--6 of Fig. 2 showing a suitabl indexing mechanism;

Fig. '7 is a diagrammatic view illustrating several principles of operation utilized in the present invention;

Fig. 8is a fragmentary elevational view of a cutter blade which may be produced by the machine shown in the drawings;

Fig. 9 is a cross-sectional view of the blade shown in Fig. 8 taken substantially on the line 9-9 of Fig. 8;

' Fig. 10 is a fragmentary elevational view of another blade which may be produced on a machine embodying the present invention; and

Fig. 11 is a fragmentary cross-sectional view of the blade shown in Fig. 10 taken substantially on the line ll--ll of Fig. 10.

Since cutter blades having configurated cutting edges such as the scalloped or serrated blades shown in Figs. 10 and 8 are popularly used in the bread slicing industry, the description of the present invention is made in connection therewith. However, it can readily be seen that the present invention can be applied to cutter blades "of many other types, including blades having both the blade holding means and the grinding wheel and motor support.

With reference to the accompanying drawings, in which like parts throughout the several views are indicated by the same reference numerals, Figs. 1 and 2 show the machine mounted on a suitable base or frame I. The frame is shown in plan view as approximately rectangular and is provided with a pair of parallel bars or rods 2 which extend between the two opposed sides of the base and serve as a slide for a blade holding means, indicated generally by the numeral 3.

Pivoted about an axis MM, which is a line parallel to the bars 2, and passing through the point of contact 0, is a suitable C-shaped support 4 upon which the grinding wheel and its driving motor may be mounted. The ends of the C- shaped member 4 are pivoted to the frame by suitable bolts 5 passing through apertures in the frame and support member. Extending through 2. lug B on th support member 4 is a screw 1 which threadedly engages a support member 8 upon which a suitable motor I may be mounted. The motor IQ may be of any suitable type provided with a shaft 'II which carries a suitable abrasivewheel I2 secured to the shaft by being heldbetween collar I3, one of which is engaged by a suitable nut I4 threaded on the end of the shaft II. To hold the support 4 against movement, suitable bolts I project through elongated arcuate apertures It in the support member 8 and through apertures in the upstanding sides of .the base I and cooperate with nuts I! carried by the bolts to clamp the support 4 with respect to the base I. The support 4 is further held by an adjustable screw I8 upon which the support 4 rests, the screw I8 being threadedly mounted in a socket 29 secured to the base I. If desired, a

calibrated disc I 9 may be secured to the screw I8 and an indicating scale I So may be fastened to the socket so that the positions of the support 4 may be readily reproduced at any time.

The blade holding means 3 is carried on a member 2| slidably mounted on both the bars 2.

Movement of the member 2| is obtained by a lever 22 provided with a handle 23 and pivoted at 24 to a collar 25 which is keyed to one of the bars 2, as indicated at 26. The end of the lever 22 opposite the handle 23 is pivotally mounted at 21 to one end of a link 28, the other end of which i is pivotally mounted to the member 2| at 30, as may be seen in Fig. 1. Thus, downward movement of the handle. looking at Fig. l, rotates the lever 22 about its pivotal mounting 24 to the collar 25 is a counter-clockwise direction and slides the member 2I along the bars 2 toward the collar 25 to pass the blade across the peripheral face of the grinding wheel. By returning the handle 23 to the position shown in Fig. l, the

member 21 will be slid away from the collar 25 and the blade will be passed across the pe ripheral face of the grinding wheel in the opposite direction.

Journalled in a central vertical aperture through the member 2I is a sipndle 3I upon which the individual'units of the blade holding mechanism are mounted. A hub 32 of a backing disc 33 is carried by a reduced portion 34 of the spindle 3i and is keyed thereto, as indicated by the numeral 35. The external surface of the hub 32 .carries adjacent the backing disc 33 a collar 36 having a locating arm 31 projecting therefrom, which arm terminates in a cylindrical portion 38. The collar 35 also has extending therefrom an arm 40. The collar 36 and locating arm 37 to the spindle by a set screw BI.

may be locked to the backing disc 33 by means of a tightening stud bolt 4| and washer 42 which stud bolt passes through an elongated arcuate aperture 54 disposed in the end of the arm 40 and is threadedly received in the backing disc 33. Above the collar 35 is a similar collar 45 embracing the hub 32 and having a locating arm 45 projecting therefrom, which locating arm terminates in a cylindrical portion 4'? having a stop member is projecting upwardly therefrom. Disposed on the hub 32 above the collar 45 is a collar 59 secured to the hub 32 by set screw 5| and having stops 52 and 53 projecting therefrom. The locating arm 46 is urged toward the stop 53 by a suitable coil spring 56 disposed in a recessed portion of the stop member 43 of the locating arm 46 and in a recessed portion in the stop 52. The stop member 48 limits the rotational movement of the locating arm 46 in a clockwise direction, looking at Fig. 3, by engagement with the stop 53, and the locating arm 46 may be moved in a counter-clockwise direction, looking at Fig. 3, against the compressive strength of the spring 54 until the stop member 48 contacts the stop 52.

The end of the reduced portion 34 of the spindle 3| carries a star wheel 55 secured to the portion 34 by a set screw 56 and held against endwise movement with respect to the spindle by washer 5'! and nut 58 which threadedly engages the reduced portion 34 of the spindle 3i.

Between the member 2i and the reduced portion 34 the spindle 3! carries a collar 56 secured The collar 60 has secured thereto a bushing 62 threaded on its outer circumferential surface. Threadedly engaging the bushing 62 is a collar 63 which carries a supporting disc portion 64 radially extending therefrom. The collar 63 is also provided with a knurled ring 55 in order that the disc 64 may be moved axially of the spindle for a purpose to be described later.

Cutter blades A are usually formed of relatively hard spring steel and when deformed or bent they normally tend to return to their flat straight-line shape. However, in order to grind curved scallops or serrations 66 in the blades A, the latter are deformed into an arcuate shape and while held against the peripheral surface of the backing disc 33 successive portions of their cutting edges are presented to the peripheral surface of the abrasive wheel I2. To provide a suitable angle between opposite sides of the cutting edge. the blade when being ground is held below the axis of the grinding Wheel. In the present machine the blade to be ground is retained in a curved position by pins 68 and III which are received in suitable holes adjacent the ends of the blades. The blade A, when mounted on the pins 68 and I0, is backed by the peripheral edge of the backing disc 33 and has its bottom or non-cutting edge supported by a shoulder 67 of the movable supporting disc 64.

The pins 68 and 10 are carried by depending portions of adjustable fittings II and I2, respecin the cutting edges of the blade.

pending from tings. The fittings H and 12 extend through vertical slots 15 in the cylindrical portions 38 and 41 of the locating arms 31 and 46. Engagement of the fittings with the sides of the slots 15 prevents. twisting movement of the pistons in their bores and retains the blade holding elements in radial positions with respect to the spindle 3|.

J In applying a blade tothe blade holding means the blade is grasped at each end with its cutting edge uppermost and the hole in the left hand end is hooked over the pin 88 of the locating arm 31. While maintaining a slight tension in the blade, it is bent around .the periphery of her 2|. When the handle 82 of the lever 8| is moved from its full line position against one stop 90 to its dotted line position against the other stop 90, as shown in Fig. 6, the pawl 85 is rotated in a clockwise direction, moving to and engaging the next tooth of the ratchet wheel so that upon return of the handle 82 to its full line position, shown in Fig. 6, the ratchet wheel 18 is rotated. in acounter-clockwise direction a distance equal .to the pitch of the teeth. The pitch of the ratchet wheel teeth is made to correspond with the length of scallops desired on the blade to be ground, so that by advancing the the backing disc 33 and the hole in the right is accomplished by loosening the stud 4|, manually rotating the arm 31 to a position which appears to be correct, and measuring with the blade to see whether the hole in the right hand end of the blade is disposed within the arc de,' fined between the stops 52- and 53. Small or fine adjustments of the stationary locating arm may be readily made by turning an adjusting screw 18 threadedly mounted through a post 11 mounted on the backing disc 33 and engaging a flat surface of the cylindrical portion, 38 of the arm 31. When the stationary locating arm is in its approximately correct location, the bolt 4| is tightened to hold the locating arm 31 sta tionary, the left end of the blade is hooked over the pin.68 and the right end of the blade is hooked over the pin 18 of the adjustable locating arm 46, the arm 46 being movable between the stops 52 and 53 in order that the pin 10 may register with the hole in the blade.

The spring 54 has suflicient strength to hold the blade under a slight tension during the grinding to prevent movement thereof which would tend to cause misalignment of the scallops or serrations 88 in the cutting edge of the blade. The position of the locating arm 48 necessary to produce the desired tension in the blade ratchet wheel'one pitch length after each scallop hasbeen ground, the spindle 3| is rotated one scallop length so that the next scallop is ready to be ground.

It maybe readily seen that the length of scallop ground onv theblade may be easily changed by replacement of the ratchet wheel with a wheel having teeth of the proper pitch. Replacement of the ratchet wheel 18 may be accomplished by unscrewing the nut 83, removing the washer 84, the collar 88 of the lever 8|, the ratchet wheel 18, and mounting a new I ratchet wheel on the spindle 3|. In reassemshould be considered in adjusting the stationary locating arm 31.

It is desirable that an indexing mechanism be provided to rotate the blade holding mechanism as a whole in equal increments so that uniform scallops or serrations may be formed The indexing mechanism is shown in Figs. 2 and 6 and comprises a ratchet wheel 18 mounted on and keyed to the spindle 3| directly beneath the sliding member 2| and adjacent thereto. Disposed beneath the ratchet wheel is a collar 88 freely mounted on the spindle 3| and carrying a projecting lever 8| terminating in a knurled handle portion 82. A nut 83 threadedly mounted on a reduced portion of the spindle 3| retains the collar 88 onto the spindle 31 with the aid of a washer 84 interposed between the nut and collar 88. v

Disposed on the lever 8| radially outside of I the ratchet wheel 18 is a pawl 85 pivoted to the lever at 88. A torsion spring 81 urges the pawl toward teeth 88 of the ratchet wheel 18. Movement of the lever 8| is limited by stops dethe underside'of the slide membling the lever 8|, washer 84 and nut 83, care I should be taken to see that the pawl properly engages the teeth of the new ratchet wheel.

, In accordance with the present invention the point of contact, that is, the point 0 in Fi '1, where the top edge of the blade blank engages the abrasive wheel 12, is made the focal point of all the movements ofthe blade holding means and abrasive wheel. In this manner the'adjustments of the wheel with respect to the blade may be accomplished very easily.

If when the blade is mounted on the holding means it is found that it does not contact the abrasive wheel due to the fact that the blade is too narrow, it is only necessary to turn the knurled ring 65, thereby raising the blade sup.- porting disc 64 until the top edge of the blade is in 'a horizontal plane passing through the point 8. Sincethe pins which hold the blade against the backing disc 33 are mountedon the fittings 1| and 12 carried by the floating friction pistons 13, the blade is readily adjustable relative to the backing disc 33. The blade mounting means of the present invention supports the blade for rectilinear edgewise bodily movement at a. right angle to the rotational axis of the grinding wheel and spaced laterally therefrom. For example, if the blade to be ground has a width such as shown in Fig. 7 equal to the distance X-8 and the machine is set for a blade having a width equal to the distance 36 0, to sharpen the blade on the machine shown in the drawings, it is only necessary to turn the knurled ring 65 until the blade supporting disc 64 is raised through the distance Y-X. Thus, it may be seen that blades of any particular width may be mounted and readily shiftedor adjusted to be ground by the present invention. In many grinding machines used commercially, to obtain the same adjustment would require both a vertical and horizontal movement of the abrasive wheel and motor support due to the fact that with the blade mounted on a sliding carriage it has not been consid- ,ing wheel l2 at the peripheral edge of the stationary backing disc 33. This gauge 9| is disposed'directly above the shoulder 6'! of the movable blade supporting disc 64 and has its gauging surface 92 in a horizontal plane containing the point 0. In using the gauge the supporting disc'B l may be raised by the knurled ring 65 so that the top edge of a blade manually supported on the shoulder 61 just contacts the underside or gauging surface 92 of the overhanging tip of the gauge 9|. To look the blade supporting disc in its proper position relative to the stationary blade backing disc 33 a cylinder 93 is disposed on the backing disc '33 and contains therein a plunger piston 94 keyed or pinned to a suitable handle 95, as indicated at 96. The plunger 94 extends through the stationary backing disc 33 and may be selectively inserted into any one of a plurality of apertures 9'! formed circumferentially around the blade supporting disc 64. The apertures 97 are spaced circumferentially to provide relatively fine adjustments.

' The usual practice in grinding serrated blades is to have the blade contact the abrasive wheel at a point such as the point I! in Fig. '7 below the axis C of rotation of the abrasive wheel l2 shown in full lines in Fig. 7. If the diameter of the abrasive wheel is reduced for any reason, such as the natural decrease due to wear, it is desirable to bring the grinding wheel closer to the blade in a line passing through the point of contact and the center of rotation C. By so doing, the grinding wheel of reduced diameter may be moved into contact with the work by a single straight line adjustment. In many machines in use today it is necesary to move the wheel in both a vertical and a horizontal direction when compensating for grinding wheel wear. Otherwise, the nature of the serrations formed on the cutting edge of the blade may be changed.

In the machine embodying the present invention this may readily be done by turning the screw 7 which moves the motor on the inclined slideof the motor support 8, which is constructed so as to be parallel with a line C0 drawn through the center of rotation of the grinding wheel and the point of contact 0.

For example, Fig. 7 showsin dotted outline a grinding wheel I2 which has a reduced diameter caused by wear. To contact the work the grindis moved along the line C-fl until its center of rotation is at C where its periphery passes through the point of contact 0. Although the width of the scallop formed in the blade will be slightly changed by using the smaller grinding wheel l2, the blade is not materially affected since the radius of curvature of the grinding wheel is relatively large with respect to the width of the blade cutting edge.

To change the angle of out which determines the angle between the cutting edges of the blade, the machine embodying the present invention has an adjustment which may be operated with ease. As previously stated, the grinding wheel support 8 is pivotally mounted by the bolts 5. The axis of rotation of these bolts, indicated by the line M-M of Fig. 1, passes through the point of contact 0 so that the center of rotation C of the grinding wheel may be rotated about the point ll. This is illustrated in Fig. 7 where it may be seen that the grinding wheel l2 shown in full lines may be rotated to its dotted line position. When the grinding wheel has been so rotated the common tangent between the blade and the grinding wheel is changed from the line BEl to the line D-El. It may be noted that this tangent largely determines the angle or cut of the blade. Figs. 8 to 11, inclusive, show blades having two varying angles of cut, the blades shown in Figs. 8 and 9 having a relatively small angle of cut and the blades shown in Figs. 10 and 11 having a relatively large angle of out, both, however, being acute angles. For many purposes a blade such as shown in Figs. 8 and 9 having a long, thin cutting edge is very desirable, but in many instances a shorter and wider cutting edge such as shown in Figs. 10 and 11 is desired due to its greater inherent strength.

It is to be understood that variations and modifications of the specific devices herein shown and described for purposes of illustration, may be made without departing from the spirit of the invention.

What I claim is:

1. A grinding machine for grinding thin metallic strips, which comprises means for holding the strip during grinding, a rotatable abrasive means having its axis above a line perpendicular to the strip and passing through the top edge of the strip, means for moving the strip transversely of itself, means for mounting the abrasive means so that it may be moved in a direction parallel to a line drawn through the top edge of the strip and the center of rotation of the abrasive means, and means for mounting the abrasive means so that it may be pivoted about the top edge of the strip when such strip is in contact with the abrasive means.

2. In a machine for grinding thin metal strips,

having a rotatable grinding wheel, means for holding strips during grinding, and means for pivotally mounting the grinding wheel about an axis parallel to the axis of the grinding wheel and passing through the point of contact of the grinding wheel and the top edge of the strip to be ground.

3. A machine for grinding thin metal strips, which comprises a rotatable grinding wheel, a sliding carriage adapted to hold a strip while being moved past the grinding wheel, a point of contact between the top edge of the strip and the wheel, and a support member for said grinding wheel pivotally mounted about an axis parallel to the axis of rotation of the grinding wheel and passing through the point of contact.

4. A machine for grinding thin metal strips, which comprises a rotatable grinding wheel, a sliding carriage adapted to hold a strip while being moved past the grinding wheel, a point of contact between the top edge of the strip and the wheel, a support member for said grinding Wheel pivotally mounted about an axis parallel to the axis of rotation of the grinding wheel and passing through the point of contact, and a grinding wheel mount carried by said support member and adapted to be moved along a line parallel to a line passing through the point 01' contact and the center of rotation of the grinding wheel.

5. A grinding machine for grinding serrations in one edge of thin metallic strips, which comprises a rotatable grinding wheel, a carriage adapted to reciprocate past said grinding wheel, means for retaining a strip to be ground on a carriage in a curved position, a point of contact between the strip to be ground and the grinding wheel disposed below the axis of rotation of the grinding wheel, means for moving the strip transversely of itself, a support member pivotally mounted about an axis parallel to the axis of the grinding wheel and passing through the point of contact, and a grinding wheel mount carried by said support member andadapted to be moved in a line parallel to a line passing through the point of contact and the center of rotation of the grinding wheel.

6. In a grinding machine for abrading edge portions of thin metallic strips having a rotatab1e abrasive means and a carriage movable past the abrasive means, holding means carried by said carriage for supporting a thin metallic strip which comprises a spindle secured to said carriage, a circular member having an abutment adapted to support an edge of a strip when the strip is held in curved position, a circular backing member rigidly held to said spindle and having its periphery disposed so that it engages a face of the strip when the strip is supported by said abutment, means for moving the circular abutment member longitudinally of the spindle, and means to secure the strip in curved position with an edge supported by said abutment and a face in engagement with the periphery of said circular backing member.

7. A grinding machine for grinding thin metallic strips'which comprises a rotatable abrasive means having its axis of rotation disposed above the top edge of the strip while the strip engages the abrasive means, a strip holding means which includes an abutment adapted to support an edge of the strip and a backing member engageable with a face of the strip, said abutment being movable with respect to said backing member to cause movement of the strip transversely of itself, a mount for the abrasive means which permits'movement of the abrasive means in a direction parallel to a line drawn through the axis of rotation of the abrasive means and the top edge of the strip when the strip is in contact with the abrasive means, and means for moving portions of the strip across the peripheral face of the abrasive means.

8. A grinding machine for grinding thin metallic strips which comprises a rotatable abrasive means having its axis of rotation disposed above the top edge of the strip while the strip engages the abrasive means, a strip holding means which includes an abutment adapted to support an edge of the strip and a backing member en'gageable with a face of the strip, said abutment being movable with respect to said backing member to cause movement of the strip transversely of itself, a mount for the abrasive means which permits movement of the abrasive means in a direction parallel to a line drawn through the axis of rotation of the abrasive means and the top edge of the strip when the strip is in contact with the abrasive means, means for moving portions of the strip across the peripheral face of the abrasive means, and a pivotally mounted member carrying said mount for the abrasive means adapted to pivot the abrasive means about a line drawn parallel to the axis of rotation of the abrasive means and passing through the contact of the abrasive means and the top edge of the strip.

9. In a machine having a rotatable wheel for grinding the edges of elongated thin flexible- 1 strips of metal, a movable carriage for holding a strip and carrying the same across the wheel, said carriage including shoulder means engageable in abutting relation with one edge of the strip and of sufficient extent to support substantially all that portion of the strip to be ground, a backing member on the carriage and engage able with one face of a strip abutting the shoulder means to stifien the strip during grinding, means for retaining a strip on the shoulder means and against said backing member, and means for adjusting said shoulder means toward and away from the backing member simultaneously along the entire length thereof to impart edgewise rectilinear shifting movement to the strip over the backing member whereby the other edge of the strip can be brought into position for engagement with a predetermined point on the wheel and whereby strips of different widths can be supported on the shoulder and against the backing member with their edges engageable with said point of the wheel.

10. In a machine for grinding scallops in the edges of elongated thin flat sided flexible strips of resilient metal, an abrasive wheel and means rotatably mounting the same, a strip holder comprising cylindrically curved backing means for receiving a metal strip and means associated with the curved backing means for retaining the received strip flatwise against the curved backing means and bent longitudinally into substantially cylindrical shape, adjustable shoulder means engageable in abutting relation with one edge of the bent strip and along substantially all that portion of the strip to be ground to support the strip during grinding, and means for shifting the shoulder means simultaneously along the entire length thereof relative to the backing means to thereby impart bodily edgewise and rectilinear movement to a bent strip retained against the backing means, means for driving the wheel to rotate the same, and means for moving the rotating wheel and the holder relative to one another to pass a supported strip across the periphery of the wheel so that one edge only of such strip is presented to the wheel for grinding.

11. In a machine for grinding scallops in the edges of elongated thin fiat sided flexible strips of resilient metal, an abrasive wheel and means rotatably mounting the same, a strip holder comprising cylindrically curved backing means for receiving a metal strip and means associated with the curved backing means for retaining the received strip flatwise against the curved backing means and bent longitudinally into substantially cylindrical shape, adjustable shoulder means engageable in abutting relation with one edge of the bent strip and along substantially all that portion of the strip to be ground to suport the strip during grinding, and means for shifting the shoulder means simultaneously along the entire length thereof in a direction parallel to the plane of rotation of the wheel and relative to the backing means to thereby impart bodily edgewise and rectilinear movement to a bent strip retained against the backing means, means for driving the wheel to rotate the same, means for moving the rotating wheel and the holder relative to one another to pass a supported strip across the periphery of the wheel so that one edge only of such strip is presented to the wheel for grinding, and said wheel mounting means including adjustable means for shifting the wheel in its plane of rotation to vary the size of the scallops produced.

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