US 3508533 A
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April 28, 1970 ABRAMS GRINDING WHEEL DRESSER AND METHOD Filed Aug. 28, 1967 INVENTOR. L UUIS ABRAME.
.ATTYE United States Patent 3,508,533 GRINDING WHEEL DRESSER AND METHOD Louis Abrams, 1930 Wellesley, Toletlo, Ohio 43606 Filed Aug. 28, 1967, Ser. No. 663,880 Int. Cl. B24b 53/00 US. Cl. 12511 3 Claims ABSTRACT OF THE DISCLOSURE A method for dressing the formed faces of grinding wheels to improve the accuracy and finish of the final grinding operation made upon a work piece or a series of work pieces. Apparatus for performing the method includes a holder for a block of a ceramic semi-crystalline material which, because of its ability to withstand high temperatures and abrasion, is effective to impart a fine finish to the formed grinding faces of the wheel without further treatment. A preferred composition for this purpose comprises a multiplicity of inorganic crystals interlocked in a glassy matrix of uncrystallized glass with the crystalline portion constituting about 50% of the material.
Background of the invention It is well known to those skilled in the art that in machine grinding operations for forming a series of identical parts, it is necessary for an operator to frequently dress the faces of the grinding wheel in order (1) to assure the proper shape of the part to be ground, and (2) to prepare the surface of the wheel so that its cutting ability can be used to its optimum extent and so that the finish imparted in the final cut is satisfactory.
Various methods and apparatus, such as diamond dressers, for dressing or forming wheels are known in the art. Once a grinding wheel has been trued or formed by these known methods, in order to obtain a high or micro-finish, it has "been heretofore necessary to dress the wheel with steel cutters, abrasive dressing wheels, or by crush dressing. These procedures are time-consuming in that they require the application of considerable care and placement of a dressing mechanism opposite the Wheel, etc.
It has been found that in fine grinding, particularly with grinding wheels of a grain size of 80 or higher, that the relatively expensive and time-consuming prior art steps of finish dressing can be substantially eliminated by the use of a hand-manipulated wheel dresser which is applied to the face of the wheel after it has been formed or trued and prior to using the wheel to make the finish grinding cut on the article being formed.
Summary of the invention It has been discovered that certain semi-crystalline ceramic materials, when used as a final grinding wheel dresser, are effective to impart to the face of the wheel a very fine finish so that extremely fine micro-finishes can be obtained on the work piece without further polishing, honing or other superfinishin'g. The recent development of a number of ceramic semi-crystalline materials, sometimes known as pyro-ceramic materials, such as those disclosed in United States Patent 2,920,971, provides materials which are relatively inexpensive but which have a high resistance to heat and abrasion. These materials, because of their particularly low thermal coefiieients of expansion, high hardness, and abrasion-resistant characteristics, are particularly adapted for this purpose and 1 See Tool Engineers Handbook, McGraw-Hill Book Company, Inc. (1949) Section 60.
are advantageous in that they may be used in both wet and dry dressing and can be readily shaped as desired.
It is an object of this invention to provide an improved wheel dressing method which, when applied to the face of a grinding wheel which has been previously trued or formed by conventional methods, will give the face of the wheel a very fine finish previously unobtainable with prior art methodsv Such semi-crystalline ceramics, such as those disclosed in United States Patent 2,920,971, mentioned above, because of their extremely low coeflicient of expansion, high density and extremely high mechanical strength and hardness, in co action with the formed faces of the grinding wheels, more efiiciently transform the formed faces into the most desirable and efficient cutting surfaces.
Brief description of the drawing FIGURE 1 is a view in perspective of a manually-held embodiment of the grinding wheel dresser of this invention, illustrated as a simple block of the ceramic semicrystalline material upon which a convenient holder is attached.
FIGURE 2 is a schematic view showing the grinding wheel dresser of FIGURE 1 being applied to the surface of a cylindrical grinding wheel.
Referring to FIGURE 1, in this embodiment, the grinding wheel dresser includes a rectangular block 10 of ceramic semi-crystalline material to which a holder 11 is clamped. In this embodiment, the leading edges 12 and 13 are linear so that the dresser may be hand-manipulated for use with a grinding wheel having a linear face or may be guided by the operator around a formed grinding wheel. It may be advantageous in other embodiments to shape the leading or working edge of the device to the shape of the formed grinding wheel. Attached to the remote edge of the block 10 is the attachment device or hold-er 11 which, in this embodiment, consists of a springbiased clamp having a pair of jaws 14 and 15 which are clamped together by a spring backing 16. Each of the jaws 14 and 15 has a folded-over portion or ear 17 and 18 respectively on each end which clamps over the lateral edges of the block 10.
Referring to FIGURE 2, the block 10 and its holder 11, which is held in the operators hand, is applied to the surface of a grinding wheel G which, as previously explained, has previously been trued or formed by prior art methods. As would be apparent to any person skilled in this art, the grinding wheel dresser would be held in contact with the surface of the wheel G and drawn back and forth as necessary to properly surface the wheel.
It has been found that the grinding wheel dresser of this invention is particularly useful in applying a final finish to both aluminum oxide and silicon carbide grinding wheels having a grain size of or higher. The exact interaction which takes place between the surface of the grinding wheel and the semi-crystalline ceramic material is not fully understood, but it is believed that this material, because of its high hardness and abrasion resistance, and because of the fact that it is a solid continuous material, as opposed to a granular or particulate dressing device, presents a more uniform surface for contact with and finishing of the grinding wheel surface. Materials of the type known as pyro-ceramic materials are available from a number of commercial sources, including the Pittsburgh Plate Glass Company of Pittsburgh, Pennsylvania, the Owens-Illinois Company of Toledo, Ohio, and the Corning Glass Company of Corning, NY.
Various other embodiments of this invention will be obvious to those skilled in the art and may be made without departing from the scope and spirit of the attached claims.
1. A method of dressing a grinding wheel comprising the steps of forming the contour of said wheel with a wheel-forming device and then further dressing the formed surface with a ceramic semi-crystalline material.
2. The method of claim 1 wherein said ceramic semicrystalline material comprises a multiplicity of interlocked inorganic crystals dispersed in a glassy matrix of uncrystallized glass with said crystalline portion constituting about 50% of the semi-crystalline material.
3. A method of dressing a grinding wheel comprising the steps of applying a block of a ceramic, semi-crystalline material to the moving surface of said grinding wheel and abrading said wheel surface to remove selected portions of the surface thereof.
References Cited UNITED STATES PATENTS 6 HAROLD D. WHITEHEAD, Primary Examiner US. Cl. X.R.