US2145888A - Abrading tool - Google Patents

Description

Feb. 7, 1939. H. R. MOULTON ET AL ABRADING TOOL Filed June 6, 1936 mvsmon H/IEOLD E. MOULTO/Y 7 39) B K/NNEY Patented Feb. 7, 1939 UNITED STATES PATENT OFFICE Anaanmc :roor.

Application June 6, 1938, Serial No. 83,904 I 12 Claims. c1. 51-409) This invention relates to improvements in abrading tools and has particular reference to improved means and process of making abrasive charged tools.

This application is a continuation in part of our co-pending application, Serial No. 744,045 filed September 14, 1934.

One of the principal objects of the invention is to provide improved means and process of making an abrasive charged abrading tool wherein the particles of abrasive will be more evenly distributed throughout the useful body of the tool, and will thereby increase the durability, emciency, and work output of said tool.

Another object of the invention is to provide improved means and process of forming an abrading tool of the above character whereby the said tool may be moulded to the shape desired and the particles of abrasive anchored in the body of the tool without reducing the body to a molten state and which will permit the use of metals and metallic alloys which have hitherto been difficult and impractical for use in forming tools of this nature. C

Another object of the invention is to provide simple, efficient and economical means, and methods of forming an abrading tool of" the above character wherein the body of the tool will be porous and of such a nature as to permit the entrance of a lubricant during the use of the tool so as to aid in keeping the abrading tool cool during use and to prevent clogging of the spaces between the cuttingpoints or particles of abrasive means held by the body of said tool.

Another object of the invention is to provide an abrading tool having a base formed of pulverized metal and abrasive which are mixed to uniformly distribute the particles of abrasive throughout the effective volume of the tool and which particles of metal are thereafter welded together so as to hold the particles of abrasive means therein and yet cause the tool to be porous to allow the entrance of gaseous, liquid or solid hardening agents by which the hardness of the tools may be controlled.

Another object is to provide an abrading tool having an abrading surface portion which may be formed in separate interfitting sections some of which are impregnated with the abrasive material and the others being free of abrasive and being adapted to act as supporting means for the article being abraded to prevent wear of the por- 'vn of Fig. VI:

the character described having means formed in the abrading surface thereof adapted to .permit the particles oi the material being abraded to collect therein and be carried from the abrading surface of the tool. Ii

Another object is to provide improved means and method of forming abrading tools wherein the portions of the tool impregnated with the abrasive material may be fitted into the base portion or body of the tool and thereafter be se- 10 cured in said fitted positions.

Another object of the invention is to provide a method of forming abrading tools having portions of the abrading surface impregnated with particles of crushed diamonds wherein the porl5 tions of the tools impregnated with said diamonds and adjacent areas of the surface which are not impregnated may be formed to a continuous curved surface.

Another object is to provide an improved meth- 90 0d of applying to the surface portions of the tools separate areas in said surface which are impregnated with abrasive means. Another object is to provide improved meansand method of forming abrading tools of the above character which will be less expensive, more durable and practical for use.

Other objects and advantages of the invention will become apparent from the following description taken in connection with the accompanying drawing, and it will be apparent that many changes may be made inthe details of construction, arrangement of parts, and steps of the process shown and described, without departing fromthe spirit of the invention as expressed in the 8.01 companying claims. We, therefore, do not'wish to be limited to the exact details and steps of the process shown and described as the preferred forms only have been shown by way of illustration. 40

Referring to the drawing:

Fig. I is a plan view of a device embodying the invention;

Fig. 11 is a sectional view taken on line lI--II 4 Fig. III is a fragmentary sectional view showing a step in the process of manufacture;

Fig. IV is a plan view similar to Fig. I showing a modified form of the invention;

Fig. V is a side elevation of the tool illustrated in Fig. I;

Fig. V1 is a plan view of another modified form of the invention;

Fig. VIII is a sectional view taken on line VII- Fig. VIII is a plan view of another modified form of the invention; and

Fig. IX is a sectional view taken on line IX-IX of VIII looking in the direction indicated by the arrows. 7

It has been usual, in most instances in the past, whenever it was desired to mix particles of abrasive with a base metal to form tools of the type embodying the invention, to heat the metal to a molten state and thereafter stir the particles of abrasive into said molten metal. The mixture thus formed was then poured into moulds of the desired shape and allowed to cool and harden. This process, although relatively inexpensive and practical from the standpoint of manufacture,

was otherwise undesirable as much difficulty was encountered in obtaining an even distribution of the particles of abrasive throughout the useful portion of the tool, that is, of maintaining the particles of abrasive and molten metal in desired mixed relation with each other. The problem encountered was similar to that of placing pieces of cork or other relatively light particles, or pieces of stone or other relatively heavy particles at a certain depth in water and of expecting the said cork or stone particles to stay at said depth without any means of holding them there. In most instances the particles of abrasive were either heavier or lighter than the molten metal and would sink or rise in said metal after it was poured into themoulds to cool and harden and thereby could not be evenly distributed throughout the effective volume of the tool. r

The present invention is, therefore, directed particularly to overcoming the above difilculties in forming tools of the moulded type by mixing the particles of abrasive in pulverized metal and .of the objects and advantages of the invention may be easily and inexpensively accomplished.

Referring more particularly to the drawing wherein like characters of reference designate like parts throughout the several views, the device embodying the invention comprises broadly a mainbody portion I formed of any suitable metal or metallic alloys, preferably of such a nature that they may be hardened if desired. The body portion I as shown in Figures I and II is formed with an annular face I shaped to the curvature desired. The radius of this curvature depends upon the type of surface which is to be formed by said tool. Although applicants have shown and described the face 2 as being annular in shape, it is to be understood that the said face may be formed to any shape desired.

The body portion I is formed of pulverized metal and an abrasive powder I of predetermined size intimately mixed in desired proportions. The mixture is placed in a mould 3 such as that shown in Fig. 111 and is compressed to the shape of said mould and heated in reducing atmosphere to cause the metal to sinter together and form one coherent mass holding the abrasive particles. Heat maybe applied during the compression operation or after the particles have been compressed to shape. If desired, instead of filling the entire body portion I with the mixture of particles of metal and abrasive, only the effective part of said body portion may be filled with said mixture and the remainder only with the metal particles. This is accomplished by forming the mixture as previously described, and placing the said mixture in that part of the mould which forms the effective part of the tool and thereafter filling the remainder of the mould with only the metal particles.

The mould 3 comprises a main portion 4 in which the mixed materials to be compressed are placed and a plunger member 5 adapted to compress said materials in said main portion. It is to be understood that this is merely a diagrammatic illustration of means by which the body portion of the tool may be formed and that applicants do not wish to be limited to this specific showing as other means may be used to accomplish the same result.

The tool is preferably formed in two separate parts, as shown in Fig. II, comprising the main body portion I and a support member 6 which is secured to said body portion by means of screws or other suitable attaching members I. It is apparent however that the said parts may be simultaneously and integrally formed if desired.

After the main body portion I has been mixed and pressed into the shape desired, the metal particles may be heated to such a temperature as to cause the said particles to sinter or weld with each other. This heating may be accomplished by any suitable means, such as a gas heated furnace or electrically operated means. Attention is directed to the fact that the metal particles are heated to such a temperature that they will slightly sinter or weld with each other and care is taken that the temperature is not increased to such an extent as to cause the metal particles to become molten. This welding of the metal particles provides means for securely holding the particles of abrasive during the use of the tool. The degree of sintering or welding may be varied to vary the porosity and strength of the body portion so as to provide means whereby the said tool may be treated with gaseous, liquid or solid hardening agents either with or without heat to vary the hardness of the abrading face 2 if desired. There are many different ways by which this hardening process may be accomplished as for instance, the tool may be quenched directly after sintering as well as being treated as above stated. It, therefore, is to be understood that applicants do not wish to be limited to any one type of hardening process, it being simply necessary to control the degree of said hardness so as to control the wear of the body portion of the tool during use. 'It may, in many instances, not be necessary to harden the base, depending upon the type and nature of the metal used. In some instances the metal, as forexample if beryllium bronze or metal of a similar nature is used it may be subsequently heat treated to modify its physical characteristics if desired. Applicants do not wish to be limited to any specific metal as their process 1) -rmits the use of many diflerent types of metals, some-of which have heretofore been difllcult to work and. impractical for use for tools of this nature. Some of the metals used by applicants and with which good results have been obtained are iron, iron alloys, nitralloy, bronses, copper, etc.

The metal particles may be pressed in the mould 3 to the shape desired either when the metal particles are hot or cold. If the particles are hot during the moulding process, a graphite or ceramic mould may be used. If cold, a metal mould may be used.

It is to be understood that although applicants have shown and described the tool as being formed of two sections I and B, the said tool may be formed in one piece if desired.

If desired the sintering and hardening process may be accomplished in a single operation by heating the base I in the presence of hydrogen and ammonia. This will, of course, require heat of a predetermined temperature and the use of proper metal particles. Care is taken during the sintering or welding operations to obtain the desired porosity so as to prevent clogging of the spaces between the cutting points of the abrasive means and also to provide perforations for the entrance of suitable lubrications during the use of the tools. These perforations also permit the entrance of the hardening gases or liquids.

Any suitable type of abrasive particles, such as crushed diamonds, carborundum, or any known abrasive means now used in the art may be employed of predetermined size frequency distribution.

It may in some instances be desirable to remove a portion of the abrading face 2 of the tool prior to its use so as to expose the cutting points of the abrasive means. This may be accomplished by grinding said base with a loose abrasive or by the use of acids. In most instances such treatment will not be necessary, depending upon the type of metal particles used and the nature and requirements of the tool.

The process in general comprises mixing particles of pulverized metal with particles of abrasive to the desired proportions, placing the mixture in a mould having the shape of the finished tool desired, compressing the particles of metal and particles of abrasive in the mould to form a substantially coherent mass, heating the particles to a predetermined temperature to bring about a sintering or welding of the particles, treating the article thus formed to increase its hardness and thereafter removing a portion of the face 2 to expose the cutting edges of the abrasive means as required.

A tool formed in the above manner wherein the said integrally united thin layer, forming the abrading surface of the tool, and the underlying portion, have a predetermined degree of porosity, an intimate heat conducting path from the abrading surface to the base of the tool will be provided whereby the heat generated during abrading will be reduced at the surface through the porous and heat transmitting nature of the body portion of the tool,

It is apparent that although applicants thus far have described-only one type of tool many different types of tools, and articles may be formed by the above process, and all of which are included in this invention.

In Figs. IV and V there is shown a tool having separate areas I!) and II, the areas I!) being formed of a mixture of particles of pulverized metal with particles of abrasive mixed to the desired proportions, secured within grooves l2 formed. in the base l3 of the tool. The portions l may be formed separately of the baseand may thereafter be secured in the grooves l2 by soft solder or other suitable means. In this particular instance the portions l0 would be shaped to fit within the grooves and provided with their exposed surfaces I 4 formed to the curvature desired on the abrading tool. The mixture thus formed or molded is heated to a predetermined temperature whereby the particles are sintered or welded together to hold the particles of abrasive therein.

The areas II in this particular instance may be formed of metal similar to the metal of the base l3 or may be formed of particles of pul verized metal similar to that with which the abrasive particles is mixed, only in this instance no particles of abrasive is placed or mixed with the metallic particles. In this particular instance the portions forming the areas ll areshaped to the desired shape and to form the grooves l2 in which the portions ID are secured and are provided with curved surfaces which, when the portions H) are fitted within the grooves l2 provide a continuouscurved surface on the face of the tool.

The object of forming a tool of the above character is to provide separate areas I!) which are adapted to do the abrading and to provide separate areas ll acting as means for supporting the work being abraded. These areas ll provide relatively large bearing surfaces for supporting the work during the abrading operation and reducing the wear of the supporting metal in which the particles of abrasive are held and thereby provide a more durable and efficient abrading tool.

It is to be understood that the curved surface of the tool, after the portions l0 have been fitted within the grooves l2, may be trued by removing a portion of .the surfaces of the areas I!) and H by abrading with carborundum or other suitable means, utilizing an abrading tool of the desired curvature which is to be formed on the face of said portions. This abrading operation, by the use of carborundum or other suitable means, also causes a predetermined amount of the cutting edges of the abrasive or diamond particles in the areas It) to be exposed.

It is also to be understood that if desired the separate areas I0 and H may be molded or otherwise formed in desired relation with each other as shown in Fig. IV and may thereafter be heated and sintered into an integral coherent mass having the desired surface curvature simultaneously formed thereon or the grooves 12 may be filled with a mixture of pulverized metal particles and particles of abrasive and may thereafter be sintered to form an integral structure.

In all of the above instances it is .to be understood that the areas Hi and H may be hardened in a manner similar to that described above in connection with the tool shown in Figs. I and III inclusive.

In Figs. VI and VII there is shown another modified form of the invention wherein the base l6 of the tool is formed with a plurality of recesses I! in which plugs l8 formed of a mixture of pulverized metal particles and particles of abrasive are placed. These plugs 8 may be formed separately similar to the portions ID, or recesses I! may be filled with -a mixture of pulverized metal particles and abrasive particles which may be thereafter sintered into an integral structure.

The various plugs 18 are provided with exposed curved surfaces l9 which join with the adjacent exposed surface 20 of the base I 6 to form a continuous curve on the face of the tool. The base l6, like the base l3, may be formed or solid metal or of pulverized sintered particles of metal similar to that utilized in the mixture forming the plug 18 or may be formed with portions thereof having one or both of the above characteristics. In instances where the plugs l8 are formed separate and are secured in the recesses [1, suitable securing means such as soft solder or other adhesive means may be used to attach them within the recesses H.

In Figs. VIII and Hi there is shown a tool generally similar to the tool illustrated in Figs. I to HI inclusive, except in this instance, the face of the tool is formed with grooves 2| which during the abrading operations provide means in which the material removed from the work being abraded may collect and through the movement of the work over the abrading tool will be caused to move outwardly of the grooves and be discharged from the abrading surface of the tool.

It is to be understood that the tools, such as shown in Figs. IV to VII inclusive, may also be formed with grooves similar to 2| if desired.

It will be noted that the groove 2| is illustrated as being of a spiral shape but the said groove may be made to any shape desired as long as it extends from adjacent the inner edge portion of the tool to the outer edge thereof and is so angled relative to the direction of movement of the tool during the abrading that the movement of the work relative to the tool during abrading will cause the material to be gathered in and ejected by said grooves during said abrading.

It will be noted that the tools shown in Figs. I to III inclusive, and in Figs. V111 and E, are provided with a relatively thin layer formed of a mixture of pulverized metal particles and abrasive particles which is of substantially uniform thickness throughout the face of the tool so 'as'to reduce the cost involved in forming such tools, particularly in instances when particles of crushed diamonds are used as the abrasive means. In this particular instance, the layer is integrally joined to the base of the tool during the sintering' operation or may be formed separately and secured to said base by solder or other suitable adhesive or by mechanical means. In the latter instance, only the layer need be replaced when the tool is worn.

The base portions of the tools shown in Figs. IV to IX inclusive, are all adapted to be attachedto a support similar to the support 6 shown in Fig. II and are all preferably provided with a central opening adapted to fit over a suitable aligning projection formed on the support 6; Suitable means, such as securing means I, is also used to secure the base portion of the tools to the supports.

It is apparent that although applicants,

throughout their specification, have continually referred to the use of metallic particles in forming the base of their tool, any suitable means or mouldable materials other than metal or in combination with the metallic particles may be used if desired.

From the foregoing description it will be seen that simple, eflicient, and economical means and process have been provided for accomplishing all of the objects and advantages of the invention,

particularly that of providing means whereby the particles of abrasive will be substantially uniformly. distributed throughout the effective volume or useful portion of the tool.

Having described om invention, we claim:

1. An abrading'tool comprising a base having a plurality of grooves therein and having a mixtured of sintered pulverized metal and particles of abrasive secured in said grooves by said sintering, said composite structure having a continuous abrading surface on one side thereof, the abrading surface of said tool being hardened to a controlled degree of hardness to control the wear of the tool during use.

2. An abrading tool comprising a base formed with a plurality of recesses therein and a sintercd mixture of pulverized metal and abrasive particles secured in said recesses by said'sintering, said composite structure having a continuous surface on one side thereof extending over portions of the base and inserts of sintered metal and abrasive, the abrading surface of said toolbeing hardened to a controlled degree of hardness to control the wear of the tool during use.

3. An abrading tool comprising a support formed with a projection on one side thereof and in secured to said support with the projection fitted in said opening, said renewable element comprising a base formed with a relatively thin layer of a sintered mixture of pulverized metal and abrasive shaped to form the abrading surface of the tool, said relatively thin layer and said underlying portion being joined into an integral structure with the relatively thin layer being of substantial equal thickness throughout and having a predetermined degree of porosity.

4. An abrading tool comprising a support formed with a projection on one side thereof and a shank portion on the opposite side, said shank portion having means for mounting a spindle in operable relation therewith and a renewable grinding element having a central opening therein secured to said support with the projection fitted in said opening, said renewable element comprising a base formed with a relatively thin layer of a sintered mixture of pulverized 'metal and abrasive shaped to form the abrading surface of the tool, said relatively thin layer and said underlying portion being joined intd an integral structure with the relatively thin layer being of substantial equal thickness throughout and having a predetermined degree of porosity, and being hardened to a predetermined degree of hardness.

5. An abrading tool comprising a support formed with a projection on one side thereof and a shank portion on the opposite side, said shank portion having means for mounting a spindle in operable relation therewith and a renewable grinding element having a central opening therein secured to said support with the projection fitted in said opening, said renewable element comprising a base formed with a relatively thin layer of a sintered mixture of pulverized metal and abrasive shaped to form the abrading surface of the tool, said relatively thin layer and said underlying portion being joined into an integral structure with the relatively thin layer being of substantial equal thickness throughout and having a predetermined degree of porosity, said abrading surface having a groove therein extending from adjacent the central portion of the surface to the peripheral edge thereof.

6. An abrading tool comprising a support having a main body portion' and a shank having said body portion opposite the shank formed of a relatively thin layer of a sintered mixture of pulverized metal and particles of abrasive shaped to form the abrading surface of the tool, said relatively thin layer being joined to said body portion and having a porous nature and a substantially equal thickness throughout.

7. An abrading tool comprising a supporting element and a renewable grinding element, one

of said elementshaving a recessed portion and the other a portion extending within said recess with the said elements in secured relation with each other, said renewable element comprising a base formed with a relatively thin layer of a sintered mixture of pulverized metal and particles of abrasive shaped to form the abrading surface of the tool, said relatively thin layer and said underlying portion being joined into an integral structure with the relatively thin layer having a porous nature and of substantially equal thickness throughout.

8. An abrading tool comprising a supporting element and a renewable grinding element, one of said elements having a recessed portion and the other a portion extending within said recess with the said elements. in secured relation with each other, said renewable element comprising a base formed with a relatively thin layer of a sintered mixture of pulverized metal and particles of abrasive shaped to form the abrading surface of the tool, said relatively thin layer and said underlying portion being joined into an integral structure with the relatively thin layer having a porous nature and of substantially equal thickness throughout and being hardened to a predetermined degree of hardness.

9. An abrading tool formed of three superimposed layers of metal each having different characteristics, comprising a first layer composed ofa sintered mixture of pulverized metal and particles of abrasive shaped to form the abrading sin-face of the tool, said first layer having a porous nature and being of substantially equal thickness throughout, a second layer formed of sintered pulverized metal integrally joined with the first layer and constituting a permanent support for said'first layer and a third layer of solid metallic material having a face shaped to engage and be detachably secured to said second layer on the side thereof opposite the first layer and constituting a temporary support for said integrally joined layers- 10. An abradirw tool comprising a mporting element having a shank portion having means for mountinga spindle in operable relation therewith and a renewable grinding element, one of said elements having a recessed portion and the other a portion extending within said recess with the said elements in secured relation with each other, said renewable element comprising a base formed with a relatively thin layer of a sintered mixture of pulverized metal and particles of abrasive shaped to form the abrading surface of the tool, said relatively thin layer and said underlying portion being joined into an integral structure with the relatively thin layer having a porous nature and of substantially equal thickness throughout.- g

11. An abrading tool comprising a supporting element having a shank portion having means for mounting a spindle in operable relation therewith and a renewable grinding element, one of said elements having a recessed portion and the other a portion extending within said recess with the said elements in secured relation with each other, said renewable element comprising a base formed with a relatively thin layer of a sintered mixture of pulverized metal and abrasive shaped to form the abradingsurface of the tool, said relatively thin layer and said underlying portion being joined into an integral structure with the relatively thin layer having a porous nature and of substantially equal thickness throughout and being hardened to a predetermined degree of hardness.

12. An abrading tool formed of three superimposed layers of metal each having diiferent characteristics, comprising a first layer composed of a sintered mixture of pulverized metal and particles of abrasive shaped to form the abrading surface of the tool, said first layer having a porous nature and being of substantially equal thickness throughout, a second layer formed of sintered pulverized metal integrally Joined with the first layer and constituting a permanent support for said first layer and a third layer of solid metallic material having a face shaped to engage and be detachably secured to said second layer on the side thereof opposite the first layer and constituting a temporary support for said integrally joined layers said third layer having a shank portion on the side thereof opposite the integrally joined layers formed having means for mounting a spindle in operable relation therewith.

HAROID R. MOULTON. In! D. men.

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