Process for plating super abrasive materials onto a honing tool

#The present invention relates to an improved method for plating super abrasive materials such as abrasives that include diamond particles, particles of cubic boron nitride and other like hard materials onto a particular substrate such as a honing tool, which method includes coating the plated abrasive bond with a thin layer of a composite material including a metal or metal alloy material containing a friction reducing or lubricating type substance such as a nickel/phosphorous alloy which contains micron-sized Teflon particles occluded therein so as to provide anti-stick and anti-gall properties to the bond between the super abrasive particles. This improved plating process substantially eliminates any galling or scoring of the honed work surface during a honing operation due to stock material which may accumulate between the abrasive particles and it increases the overall service life of the honing tool. Although coating the abrasive bond with a nickel/phosphorous/Teflon (Ni-P-PTFE) composite material is preferred, it is recognized that a wide variety of other metal or metal alloy composite materials containing a friction reducing type agent may likewise be utilized to provide the desired anti-stick and anti-gall properties to the bond.

#The abrasive portion of a honing tool is the working portion of the tool as it is this portion of the tool which engages a particular workpiece under pressure during a honing operation and removes material therefrom until the desired final diameter of the workpiece has been achieved. As stock is being removed from a workpiece during a honing operation, metal chips and shavings have a tendency to load or stack up between the protruding abrasive particles on the honing tool, such build-up eventually leading to galling or scoring of the honed work surface. This is a continuing and on-going problem in many honing operations and the accumulation or adherence of such stock material between the abrasive particles is particularly true of ductile type materials such as stainless steel which produce long stringy chips or shavings during the honing process. Typically, such long stringy chips will fill up or clog the spaces between the protruding abrasive particles on the tool and then, after they have been hardened by compaction through the honing action itself, enough heat is eventually generated during honing that these chips or shavings will actually weld and bond themselves to the bonding matrix between the adjacent abrasive particles thereby causing galling or scoring of the honed work surface as the honing operation continues. Also, this stock material build-up reduces the cutting effectiveness of the abrasive particles and, once the abrasive particles wear to the same surface level as the stock build-up between such particles, any effective cutting action is eliminated. This phenomena therefore not only diminishes the quality of the finished work product but it also diminishes the overall service life of the tool and eventually leads to the termination of such tool as an effective cutting member.

#Various means have been utilized in an effort to reduce and minimize the occurrence of having stock material build-up and collect between the abrasive particles of a honing tool thereby causing the aforementioned problems. For example, U.S. Pat. No. 4,155,721 discloses a dual bonding process for making single layered grinding tools wherein a metallic substrate is pre-etched so as to suitably cavitate the substrate surface prior to plating. Etching is believed to create small cavities in the substrate surface, each such cavity being adapted to individually receive a portion of an abrasive particle. This arrangement provides a stronger mechanical bond between the abrasive particles and the metal plated surface of the substrate so that at least a portion of the abrasive particles are recessed below the shear plane. This process further includes a second plating step wherein a second metallic bond matrix can thereafter be applied over the first metal coating to prevent stock build-up and adherence to the bond matrix between the abrasive particles. This second plating bath is comprised of metal ions only and, when the type and thickness of this second coating of metal is properly selected for the intended application of the tool, this second coating of metal between the abrasive particles helps to prevent glazing of the cutting edge of the tool due to the same stock build-up between the abrasive particles as previously explained.

#FIG. 1 is a side-elevational view of one embodiment of a typical honing mandrel, including a tubular honing member and an expander member which is slidably movable therewithin;

#FIG. 2 a side-elevational view illustrating the first plating process associated with the present invention;

#FIG. 3 is a side-elevational view illustrating the second plating process associated with the present invention;

#Referring to the drawings more particularly by reference numbers wherein like numbers refer to like parts, number 10 in FIG. 1 identifies one of many possible embodiments of a typical honing tool or mandrel commonly used for attachment to a honing machine to accomplish a honing operation. The honing tool or mandrel 10 includes an elongated substantially tubular honing member 12 having a passageway or bore (not shown) extending therethrough from end-to-end adaptable for cooperatively receiving an expander member or arbor 14 positioned therethrough. The honing member 12 includes an outer surface 16, preferably substantially cylindrical, a portion 18 of which is typically plated with a super abrasive material as illustrated in FIG. 1. Such super abrasive materials typically include diamond particles or particles of cubic boron nitride in a suitable binder or other like hard materials. Use of such super abrasive materials is well known in the honing art. Typically, only a portion of the honing tool is plated with such abrasive particles and the specific arrangement and amount of coverage of such abrasive particles on a particular honing tool is usually dependent upon the particular application and the surface finish desired after honing. Although a specific abrasive configuration is illustrated in FIG. 1, it is recognized that a wide variety of different abrasive patterns may be utilized depending upon the particular application desired and the type of super abrasive material being used. Nevertheless, regardless of the specific arrangement and amount of coverage of a particular super abrasive material, the present invention is directed specifically and particularly to an improved process for plating such super abrasive particles onto the working portion of the honing tool such as the abrasive portion 18 illustrated in FIG. 1. Other honing tool or mandrel constructions for which the present invention is likewise particularly useful are those single pass through honing tool constructions disclosed in Sunnen U.S. Pat. Nos. 4,197,680 and 4,253,279 as well as a variety of radially expandable mandrel constructions such as the construction illustrated in FIG. 7. Other radially expandable mandrel constructions having particluar utility for the present invention include those constructions disclosed in Sunnen U.S. Pat. Nos. 3,216,155; 4,524,549; and 4,555,875.

#More specifically, the present improved process or method utilizes a nickel/phosphorous/Teflon (Ni-P-PTFE) composite material, or other metal or metal alloy material having a friction reducing or surface lubricating type material occluded or otherwise associated therewith, as the anti-galling agent for applying to and coating the bond established between the plated abrasive particles and the honing tool once such particles are bonded by known techniques to such tool. Although any suitable means for attaching or bonding the abrasive particles to the tool substrate may be utilized without impairing the teachings of the present invention, an electroplated process is generally preferred. In this regard, multi-layers of a super abrasive material such as diamond particles and/or cubic boron nitride particles are positioned and held against the tool substrate and an initial thin layer of an electroplated material is applied thereagainst using known techniques in order to hold and attach the adjacent first layer of particles to the substrate. The results of this first plating process or bath are illustrated in FIG. 2 wherein multi-layers of a super abrasive grit 20 are held against the tool substrate 22 and an initial thin bond of electroplated material 24 is formed by and between the first adjacent layer of abrasive grit particles 21 and the tool substrate 22. Well known electro plating processes are available for accomplishing this task. Electroplated materials typically used for this type of bond application include such metals as nickel, copper, cobalt and chromium; such metal alloys as nickel phosphorous, nickel boron and brass; and other materials including autocatalytic or electroless plating. Autocatalytic plating refers to a process wherein the deposit material itself catalyzes the reduction reaction at the tool surface.

#After this first initial electroplated or electroless plated process is applied to the particular abrasive particles and the associated substrate, the adjacent first layer of particles such as the particles 21 illustrated in FIG. 2 is only loosely secured or bonded to the substrate 22. In other words, this initial bond 24 covers only a very small portion of the overall height of the individual abrasive particles forming the adjacent layer. Once this first plating process is completed, the surplus layers of abrasive particles 20 (FIG. 2) are thereafter removed by known means and the plating process or bath is re-activated and a thicker plated deposit is applied to the initial bond 24 illustrated in FIG. 2 thereby further bonding the first layer of abrasive particles 21 to the substrate 22. This re-activation of the plating process (second plating process) allows additional electroplated material 26 to be applied to the previous bond 24 to build-up the bond between such particles and the substrate 22. In this regard, use of the term "bond" in describing the present process refers to a mechanical bond, not a chemical or metallurgical bond. The plated deposit material produces a close fitting socket that fills into the irregular abrasive grit surface to attach such abrasive grit to the tool substrate. The results of this second plating process are illustrated in FIG. 3.