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.
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.
These and other features of the present invention will become readily apparent upon further review of the following specification and drawings.
Similar reference characters denote corresponding features consistently throughout the attached drawings.
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.
A guide bar support plate 26 is secured within the guide bar track 24, e.g. with allen screws or other suitable locking means. The guide bar plate 26, and all structure attached thereto, may be adjusted and secured linearly along the track 24 as required, depending upon the sharpening operation being performed. The guide bar plate 26 includes two mutually opposed bar supports 28, with a curved guide bar 30 extending therebetween. The guide bar 30 is curved toward the guide bar support plate 26 between the ends of the bar 30, 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 plate 26 and its guide bar 30 may 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.
A blade clamp arm 36 is secured to the blade clamp arm base 32, and may be articulated through a limited angular range relative to the curved guide bar 30. The clamp arm 36 is positionally locked to the clamp arm base 32 by a position lock screw 38. When this locking screw 38 is loosened, the blade clamp arm 36 may 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 clamp 40 is pivotally secured to the blade clamp arm 36 at pivot 42. This arrangement allows the jaws of the blade clamp 40, and accordingly a scissor blade B clamped therein, to be set at a limit relative to the honing or sharpening disc 18 corresponding to the edge angle of the blade.
The series of holes or passages 48a through 48f correspond 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 disc 18 when the blade clamp arm 36 is lowered to place the blade edge against the honing disc 18. The holes 48a through 48f are 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 arm 40 as desired. In the example shown in
The right hand scissor blade B may then be positioned and clamped within the blade clamp jaw 44. 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 pin 50 is installed in the appropriate hole or passage 48a through 48f in the blade clamp 40. In the example illustrated in
At this point the blade clamp assembly is positioned generally medially along the length of the curved guide bar 30, and the blade B is adjustably positioned in the jaw 44 to allow both the base end and the tip of blade B to reach the edge of the disc 18 as the blade clamp assembly slides back and forth along the curved guide bar 30. Stops 60 (
Once the above adjustments have been completed, the actual sharpening operation may be carried out. The blade clamp arm assembly, comprising the blade clamp base 32, blade clamp arm 36, blade clamp 40, and blade clamp jaw 44 with the right hand scissor blade B secured therein, is rotated about the guide bar 30 for clearance, and power is applied to the honing disc 18, either by turning on and setting the speed control 20 as desired, or by means of a separate on/off switch. The honing disc 18 is 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 arm 30 to lower the cutting edge of the blade B into contact with the edge of the honing disc 18. The operator need only slide the blade clamp arm assembly back and forth along the curved guide bar 30 between the two stops 60, to sharpen the curved edge of the blade B along its entire length.
The proper bevel angle is automatically provided when the blade clamp arm assembly is rotated about the guide rod 30 to place the scissor blade B in contact with the edge of the disc 18 and the blade clamp 40 is retracted to its maximum extent toward the blade clamp arm 36, i.e. the stop pin 50 is contacting the underside of the blade clamp arm extension 52. However, it will be seen that the blade clamp 40 may be pivoted outwardly away from the blade clamp arm 36, i.e. counterclockwise in
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 disc 18 until the blade is sharp. Different discs may be interchangeably installed upon the drive spindle 54 as 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 jaw 44 and 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.
Initially, the blade clamp arm assembly, comprising the blade clamp arm 36, blade clamp 40, and blade clamp jaw 44, is adjusted angularly from a position slightly to the right of a line normal to the guide bar 30 to 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 in
The direction of rotation of the disc 18 is also reversed by means of the switch 22 (
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.
It is to be understood that the present invention is not limited to the embodiment described above, but encompasses any and all embodiments within the scope of the following claims.
This application is a continuation in part of U.S. patent application Ser. No. 11/159,069, filed on Nov. 22, 2004.
Number | Date | Country | |
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Parent | 11159069 | Nov 2004 | US |
Child | 11285081 | Nov 2005 | US |