Scissor sharpening machine

The scissor sharpening machine includes a honing disc with a curved blade guide and a blade clamp assembly which slides axially along the blade guide. The curvature of the blade guide corresponds to the conventional curvature along the lengths of the blades of a pair of high quality scissors or shears, and assures that they are sharpened properly. The blade clamp assembly includes a series of predetermined stops to set the proper bevel angle during the sharpening process. However, the blade may be rocked about its longitudinal axis to the limit set by the stop, in order to provide a convex curvature to the blade edge if so required. The apparatus may include a cabinet with motor controls and other components, and the blade guide and blade clamp assemblies may be adjusted and repositioned to allow sharpening of either left hand or right hand scissors and shears.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to sharpening tools and equipment. More specifically, the present invention comprises a scissor sharpening machine which retains the conventional curvature along the length of the scissor blade, while simultaneously providing the proper bevel angle or convex edge across the edge of the blade during the sharpening process.

2. Description of the Related Art

High quality scissors and shears are conventionally constructed with the cutting edges of the blades having a large radius curvature along their lengths, in order to provide a more constant included angle between the two blades as they close upon one another during the cutting operation. The radius of curvature used is nearly universally 800 millimeters, or about 31.5 inches. This is particularly true of scissors and shears used in the hair cutting and beauty salon fields, where the scissors used are nearly always quite costly to purchase and of very high quality.

Some of these scissors may cost as much as a few hundred dollars to purchase. Naturally, the owners of such costly scissors are concerned that when they are periodically sharpened, that the sharpening operation be conducted properly. This is not always the case with many conventional sharpening machines and operations. Many of the existing scissor sharpening machines available do not follow the true curvature along the length of the scissor blade, but rather form a series of straight edges with slight angles therebetween. Other sharpening machines have been constructed to follow the 800 mm curvature along the length of the blade, but cannot provide an accurate bevel angle along the blade edge, or form the required convex curvature of the blade edge where such curvature is required.

The present inventor is aware of various scissor sharpening machines and tools which have been developed in the past. One such device is described in Japanese Patent Publication No. 59-115,151 published on Jul. 3, 1984, comprising a manually powered device having a guide roller for the honing stone with the guide roller having a convex curvature along its length in order to follow the curvature of the blade along the length of its cutting edge. While the angle of the scissor blade may be set to form a specific bevel along the blade edge, there is no means to provide a convex edge, as is required for some scissor blades.

Japanese Patent Publication No. 2-036,057 published on Feb. 6, 1990 describes (according to the drawings and English abstract) two sets of rotary grindstones having a variably adjustable angle between the axes of the two sets. This allows the angle of the cutting edge to be adjusted according to that originally manufactured for the blade. However, this device cannot follow the 800 mm (or other) curvature along the length of a scissor blade, nor can it allow the blade to be rotated about its elongate axis during the sharpening operation in order to form a convex curvature along the cutting edge of the blade.

None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus, a scissor sharpening machine solving the aforementioned problems is desired.

SUMMARY OF THE INVENTION

The scissor sharpening machine includes an interchangeable circular honing disc, a blade guide assembly, and a blade clamp assembly which moves along the blade guide assembly during the sharpening operation. The blade guide assembly includes a guide bar having an 800 mm radius curvature (or other curvature, depending upon the requirements of the blade to be sharpened), with the blade clamp assembly being slidably secured along the guide bar. Precision bearings are used between the blade clamp assembly and the guide bar, in order to, preclude any movement of the clamp assembly relative to the guide bar other than axially along the length of the guide bar and circumferentially about the guide bar. The blade clamp assembly includes a stop pin and a series of stop holes or passages for setting the blade edge bevel angle relative to the honing disc as required, depending upon the originally manufactured blade edge bevel angle.

The device is used by clamping a scissor blade within the clamp assembly, adjusting its angle relative to the honing disc, and setting the blade clamp stop to correspond with the bevel angle of the blade edge. Power is then applied to rotate the circular honing disc, and the scissor blade is drawn back and forth from its tip to its root along the edge of the honing disc to sharpen the blade. The bevel angle of the blade is determined according to the predetermined stop set in the clamp assembly, which limits the angle of the blade relative to the honing disc. However, the blade may be rotated about its longitudinal axis to the limit set by the stop, in order to form a convex curvature along the blade edge if such is required. The 800 mm curvature along the length of the blade is assured according to the correspondingly curved guide bar, along which the blade clamp assembly travels during the sharpening operation.

The above described sharpening machine may further include a cabinet for housing the drive motor for the honing disc, as well as speed and directional controls for the motor. The cabinet preferably includes means for repositioning the guide bar assembly and other components in order to allow the apparatus to be reversed for sharpening both left hand and right hand scissors, as desired.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention comprises a scissor sharpening machine capable of maintaining the proper curvature along the length of a scissor blade, as well as maintaining the proper bevel angle or convex curvature (depending upon the specific scissor blade configuration) across the blade edge. The present machine proper includes a curved blade guide bar with a blade clamp assembly slidably disposed therealong, to accommodate the curvatures and angles required in sharpening a high quality pair of scissors or shears. However, the present invention may include a base cabinet with its motorized flat plate honing disc and other features and/or accessories, as well.

FIG. 1provides a perspective view of the present scissor sharpening machine and cabinet in combination therewith, collectively identified by the reference numeral10. The cabinet12provides a flat mounting base14thereatop for the installation of the sharpening machine apparatus thereon, and may include additional storage areas for different honing and polishing discs and other articles as desired. A light and magnification lens16is installed conventionally above the mounting base surface14, to facilitate the precision work required when sharpening a high quality pair of scissors or shears. The cabinet12is relatively small and lightweight, and may be placed upon a cart or carried by hand for portability. The cabinet12includes a conventional electric motor (not shown) which drives a flat blade sharpening or honing disc18, with the disc18extending above the machine mounting base14at the top of the cabinet12and rotating in a plane parallel to the plane of the mounting base surface14. Appropriate motor controls, e.g. a speed rheostat or control20and rotational direction switch22, are provided at some convenient location on the cabinet12.

FIGS. 3 through 5illustrate details of the guide bar track assembly which serves to attach the present sharpening apparatus to the cabinet12. A guide bar track24(shown inFIGS. 1,4and5) is permanently and immovably affixed atop the mounting base surface14adjacent to the honing disc18, with the track24providing for the removable and adjustable attachment to the cabinet of the various components comprising the present sharpening machine as well as positioning those components adjacent to the honing disc18. The track24may comprise a flattened “U” channel cross section with inwardly turned retaining flanges, as shown, or a “T” cross section or other suitable shape or configuration as desired.

A guide bar support plate26is secured within the guide bar track24, e.g. with allen screws or other suitable locking means. The guide bar plate26, and all structure attached thereto, may be adjusted and secured linearly along the track24as required, depending upon the sharpening operation being performed. The guide bar plate26includes two mutually opposed bar supports28, with a curved guide bar30extending therebetween. The guide bar30is curved toward the guide bar support plate26between the ends of the bar30, preferably having a radius of 800 millimeters or about 31.5 inches. This corresponds to the 800 mm curve along the lengths of the blades of most high quality scissors and shears, and enables the present machine to hone and sharpen such curved blade edges accurately while maintaining the desired curvature. However, it will be understood that the guide bar plate26and its guide bar30may be exchanged for other plate and bar assemblies having guide bars of other radii corresponding to other blade curvatures, if so desired. The process by which a scissor blade B is sharpened along the length of its curved edge is explained in detail further below, following a detailed description of the structure of the present blade sharpening device.

FIGS. 2 and 4through6provide illustrations of the blade clamp assembly which extends from the curved guide bar30. A blade clamp assembly is slidably secured to and extends generally radially from the curved guide bar30. The blade clamp assembly includes a blade clamp base32which is secured to the guide bar30by a linear bearing34. The bearing34allows the clamp arm base32to slide linearly along the guide bar30and to rotate around the guide bar. However, the linear bearing34precludes any angular shifting or play of the clamp arm base32relative to the guide bar30, i.e. the bearing axis of the clamp arm base32remains in angular alignment with the longitudinal axis of the guide bar30. (However, the clamp arm36and clamp which extend from the clamp arm base32are angularly adjustable relative to the base32, as illustrated particularly inFIGS. 2,4, and6and explained further below.)

A blade clamp arm36is secured to the blade clamp arm base32, and may be articulated through a limited angular range relative to the curved guide bar30. The clamp arm36is positionally locked to the clamp arm base32by a position lock screw38. When this locking screw38is loosened, the blade clamp arm36may be swiveled slightly to the left or to the right (when viewed from above) to position the blade clamp assembly for sharpening left or right hand scissor blades, as appropriate. This procedure is explained in detail further below.

A scissor blade clamp40is pivotally secured to the blade clamp arm36at pivot42. This arrangement allows the jaws of the blade clamp40, and accordingly a scissor blade B clamped therein, to be set at a limit relative to the honing or sharpening disc18corresponding to the edge angle of the blade.FIG. 4of the drawings provides a clear illustration of this principle. The blade clamp40includes a jaw44having a clamping screw46therein, which secures the scissor blade B between the clamping screw and the base of the clamp assembly. The clamp40also includes a series of holes or passages48athrough48ftherethrough, and parallel to the axis of the pivot42. A limit pin50(shown in broken lines inFIG. 4, for clarity in the drawing Fig.) is selectively installed within one of these blade angle limiting passages48athrough48f, to limit the angular travel of the blade clamp40relative to the blade clamp arm36. The limit or stop pin50contacts the underside (shown inFIG. 4) of the extension52of the blade clamp arm36to limit the angular motion of the blade clamp40relative to the clamp arm36.

The series of holes or passages48athrough48fcorrespond to the various blade edge angles conventionally provided by scissor manufacturers, and allow the user of the present device to set the blade angle precisely relative to the honing or sharpening disc18when the blade clamp arm36is lowered to place the blade edge against the honing disc18. The holes48athrough48fare preferably formed to provide a series of incremental jaw angle stops separated by five degrees from one another and beginning at twenty degrees, i.e. 20, 25, 30, 35, 40, and 45 degrees. These angles correspond to the blade edge bevel angles found in virtually all commercially manufactured scissors. However, it will be seen that other blade angle stops or limits may be provided in the present tool or machine, merely by forming the stop or limit holes in different locations along the arm40as desired. In the example shown inFIG. 4, the upper edge of the stop pin hole48eis precisely aligned with the lower surface of the clamp arm extension52, as would be the case if the stop pin50were installed through the hole48eand the jaw44lowered to its maximum extent. This corresponds to a blade bevel angle of 40 degrees, as commonly found in many commercially manufactured scissors and shears.

FIGS. 1 through 4illustrate the operation and use of the present scissor sharpening machine with a blade B from a right hand pair of scissors. The machine is used by first installing the desired honing or polishing disc18on the motor spindle or shaft54(shown inFIG. 4), and confirming that the rotational direction switch22(FIG. 1) is set for the desired direction of rotation for the disc18. The disc speed control20may also be set as desired at this time, if a separate on/off switch is provided for the disc drive motor. The blade clamp assembly, comprising the blade clamp arm36and blade clamp40, is oriented relative to the blade clamp base32for right hand sharpening operations (as shown in solid lines inFIG. 6), and the left/right arm position lock screw38is secured. Also, a splash guard56is installed on the track24to preclude lateral splash or spatter from water used on the disc during the sharpening process. The guard56includes two opposed slots58aand58balong one side thereof, allowing that side to be slid into place along the track24. The guard56is shown installed to the left side of the disc18inFIG. 1for right hand blade sharpening operations, with the slot58aengaging the track24.

The right hand scissor blade B may then be positioned and clamped within the blade clamp jaw44. The blade configuration has been determined by this point, i.e. the bevel angle or convex curvature across the blade edge, and the blade jaw angle limit pin50is installed in the appropriate hole or passage48athrough48fin the blade clamp40. In the example illustrated inFIGS. 2 and 4, the pin50has been installed in the forty degree bevel angle hole or passage48e.

At this point the blade clamp assembly is positioned generally medially along the length of the curved guide bar30, and the blade B is adjustably positioned in the jaw44to allow both the base end and the tip of blade B to reach the edge of the disc18as the blade clamp assembly slides back and forth along the curved guide bar30. Stops60(FIGS. 3,5, and6) are secured in place at the desired travel limits of the blade clamp assembly along the guide bar30, and corresponding travel of the blade B back and forth across the edge of the disc18. Minor fine adjustment may be accomplished as needed at this point, to assure that the cutting edge of the blade B remains in constant contact with the honing or polishing disc18as the blade B is moved back and forth as the blade clamp assembly traverses the curved guide bar30.

Once the above adjustments have been completed, the actual sharpening operation may be carried out. The blade clamp arm assembly, comprising the blade clamp base32, blade clamp arm36, blade clamp40, and blade clamp jaw44with the right hand scissor blade B secured therein, is rotated about the guide bar30for clearance, and power is applied to the honing disc18, either by turning on and setting the speed control20as desired, or by means of a separate on/off switch. The honing disc18is moistened as desired or required; water is generally applied to the disc to keep the blade edge cool during honing operations. The blade clamp arm assembly is then rotated about the guide arm30to lower the cutting edge of the blade B into contact with the edge of the honing disc18. The operator need only slide the blade clamp arm assembly back and forth along the curved guide bar30between the two stops60, to sharpen the curved edge of the blade B along its entire length.FIG. 3provides an illustration of this effect, with a first position shown in solid lines to the right with only the tip of the scissor blade B in contact with the outer edge of the disc18, and a second position shown in broken lines illustrating the base or root of the blade B in contact with the edge of the disc18. It will be seen that intermediate positions between the two positions shown, result in intermediate areas of the blade B edge being in contact with the edge of the disc18. Thus, the entire curved edge of the blade B is honed or sharpened with a constant, uniform curvature as it passes across the edge of the disc18, as the scissor blade B moves inwardly and outwardly relative to the center of the disc18as the blade clamp arm assembly traverses along the curved guide rod30.

The proper bevel angle is automatically provided when the blade clamp arm assembly is rotated about the guide rod30to place the scissor blade B in contact with the edge of the disc18and the blade clamp40is retracted to its maximum extent toward the blade clamp arm36, i.e. the stop pin50is contacting the underside of the blade clamp arm extension52. However, it will be seen that the blade clamp40may be pivoted outwardly away from the blade clamp arm36, i.e. counterclockwise inFIG. 4. This allows the operator to form a convex curvature across the cutting edge of the blade B, as is required on some scissors and shears. The operator need only swivel or rock the blade clamp40about its pivot42with the blade clamp arm36as the blade B traverses across the edge of the honing disc18, as shown inFIG. 3and described further above. The blade clamp arm36is free to pivot circumferentially about the guide bar30as the blade clamp40and blade B are rocked or pivoted about the pivot42, thus allowing the blade B to remain in constant contact with the edge of the disc18.

The blade sharpening operation continues as described above, with it generally requiring only a few passes back and forth along the edge of the honing or sharpening disc18until the blade is sharp. Different discs may be interchangeably installed upon the drive spindle54as desired or required, depending upon the amount of material which must be ground away to provide the desired curvature and blade edge angle, the finish required for the completed operation, etc. Once one scissor blade B has been sharpened, it is removed from the clamping jaw44and its mate secured therein, and the process repeated for the second blade.

The present sharpening machine may be used to sharpen left hand scissor blades as well as right hand blades.FIGS. 5 and 6illustrate the configuration of the device for sharpening left hand scissor blades. Reconfiguring the machine from right hand blade sharpening operation to left hand sharpening operation requires only a few steps, and may be accomplished in less than a minute by an experienced operator of the present sharpening machine.

Initially, the blade clamp arm assembly, comprising the blade clamp arm36, blade clamp40, and blade clamp jaw44, is adjusted angularly from a position slightly to the right of a line normal to the guide bar30to a position slightly left of such a normal line. The initial position for use in sharpening right hand scissor blades is shown in solid lines inFIG. 6, with the adjusted position for left hand blades being shown in broken lines in that Fig. This is accomplished by loosening the left/right position lock screw38in the blade clamp base32, and swinging the blade clamp arm assembly angularly about its pivot62. This adjusts the sweep angle between the scissor blade and the rotating honing disc18, with the tip of the scissor blade remaining behind the center of the disc for both left and right hand sharpening. The blade clamp arm handle tab64is also reversed from the right side (as shown inFIG. 3and inFIG. 6in solid lines) of the scissor blade clamp40, where it attaches below the jaw44, to the left side (as shown inFIG. 5and inFIG. 6in broken lines). Mirror image locator pins66are provided on each side of the blade clamp40, with a handle locking screw68securing the handle64to the right side (for right hand blades) or left side (for left hand blades), as desired.

The direction of rotation of the disc18is also reversed by means of the switch22(FIG. 1), and the splash guard56is reversed to the right side of the disc18, as shown inFIG. 5. This is easily accomplished by inverting the guard56so that its second slot58bis oriented downwardly, and sliding the edge having the second slot58binto the right hand end of the track24. The result is generally as shown inFIG. 5of the drawings. The left hand scissor blade is installed in the blade clamp44in essentially the reverse orientation of that used for a right hand blade, i.e. with the handle extending to the left and the blade to the right, as viewed inFIG. 5. The sharpening operation is accomplished in essentially the same manner as described further above for a right hand scissor blade, i.e. the blade is worked back and forth (left to right, inFIG. 5) across the edge of the honing disc18, with the curved cutting edge of the blade following the edge of the disc due to the corresponding curvature of the guide bar30. The operator may hold the blade angle constant against the stop pin50in the blade clamp40, or may rock the blade about the pivot axis42to form a convex curvature across the cutting edge, depending upon the blade configuration being sharpened. Other operations using coarser or finer discs, etc., are accomplished in essentially the same manner for either right or left hand blades.

In conclusion, the present sharpening machine not only maintains the precise 800 millimeter curvature along the length of the cutting edge of a scissor blade, but also assures that the precise bevel angle across the cutting edge of the blade is maintained during the sharpening operation. The limit or stop for the blade clamp arm assures that the bevel angle is precisely reground during the sharpening operation. Alternatively, the operator may form a convex curvature across the cutting edge where required, by rocking the blade about the pivot axis of the blade clamp pivot between the blade clamp arm and blade clamp. The versatility of the present sharpening machine enables an operator to sharpen the blades of either right hand or left hand scissors with equal ease. In consideration of the cost of extremely high quality scissors and shears, and the risk to the investment in such scissors and shears when they are improperly sharpened, the present sharpening machine will prove to be a most useful tool for those engaged in the scissor sharpening profession or activity, and will be much appreciated by the owners of high quality scissors and shears.