US2897810A - Wheel dressing tool - Google Patents

Description

Aug. 4, 1959 F. M. D'AMATO 2,397,810.

WHEEL DRESSING TOOL Filed Dec 17, 1956 INVENTOR. FLOR) M. D'QMATO BY 1 6a a/ncb dwhm/ ATTORNEYS United States Patent WHEEL DRESSING TOOL Flory M. DAmato, Cleveland, Ohio Application December 17, 1956, Serial No. 628,767 I 6Claims. c1.12s--11 This invention relates in general to dressing tools for abrasive grinding wheels, and relates more specifically to diamond dressing tools for all types of wheels.

The types of abrasive wheels, their uses and characteristics, and the reasons why dressing of such wheels is necessary, are too well known to need enumeration here. Whereas it is necessary from time to time to dress or true a wheel to produce satisfactory workpiece finish, it is also a function of the dressing tool to form the wheel surface to a specific contour for grinding contoured shapes.

In use, the tiny abrasive grains, which make up the grinding wheel and do the cutting, become dull and clogged during the work grinding cycle. A hard diamond point will resharpen the wheel by fracturing the dull abrasive grains to produce new sharp pointed ones and by removing the material in the clogged pores of the wheel.

In diamond dressing of abrasive grinding wheels, the angle of approach of the dressing tool is quite important for best results. Whenever possible, the dressing tool should be adjusted so that the diamond point drags at an angle of to 15 below a line drawn through the center of the grinding wheel and the point of contact of the diamond. This will prevent chatter and at the same time create a new point on the diamond while wearing out the original one.

The use of industrial diamonds to dress abrasive grinding wheels has speeded up the wheel dressing process to a considerable extent, and made possible good dressing in some cases where other forms of dressing tools are not satisfactory. However, it is customary in dressing a wheel to use a tool having either a single point or a cluster of diamonds. When much dressing is necessary, the custom is to start first with a roughing diamond dressing tool and then follow with a finishing tool, particularly if an extremely high degree of surface finish is required on the finished workpiece. Changing of the dressing tool is a time wasting process which eliminates some of the gain achieved by using a diamond in the first place. Furthermore, for some reason, regardless of how fine the finish dressing tool might be, it very often happens that a foreign piece of matter will stick to the surface of a wheel and cause a mar on the workpiece later ground. My invention insures the elimination of such particles clinging to the wheel surface.

It is the primary object of the present invention to provide improved wheel life and cutting ability as Well as a true wheel form by applying simultaneous wheel dressing operations in a common surface path.

Another object of this invention is to provide the correct approach angle for a dressing tool with respect to the surface of a wheel.

Another object of the invention is therefore to achieve a rough and a finished'dressing operation at one time in a common surface path to thereby reduce the number of dressing passes across the wheel.

Another is to provide a wheel grain closing action 2 under particular circumstances for obtaining a finer ground workpiece surface.

Another object of the present invention is to permit the operator to overcome mechanical error of the holding fixture of a particular grinder.

A further object of the present invention is to provide a pair of dressing tools in tandem relationship which may be used to produce a rough and finished cut in a particular given portion of the wheel in close proximity for producing an improved wheel surface.

Another objectof the present invention is to produce a wheel dressing tool which provides a superior open grain wheel finish with less time required for dressing the wheel to thereby produce more wheel life and longer dressing tool life.

Still another object of the present invention is to eliminate the need or use of diamond turning devices and diamond indexing devices which are expensive in first cost and costly to maintain.

Even though very hard, a diamond does wear as a wheel is dressed. The wear will actually introduce an error into the wheel surface even in one pass. As the diamond surface wears away, the softer interior is exposed, and such error is increased. It is the object of this invention to provide a follower tool to sweep the surface and filter away minute imperfections thus produced.

Yet another object of the present invention is to spread the pressure of the dressing points on the wheel at two points of contact to thereby reduce heat and friction on the diamond with the result that a minimum of wear is produced on both the grinding wheel and the diamond tool.

And finally, another object of the present invention is to provide a diamond tool which can dress both the face and the side of a wheel and thereby make possible accurate dressing of 90 shoulders in a contour face grinding wheel.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawing, in which:

Figure l is a face view of the preferred yoke type embodiment of the invention; Figure 2 is a side elevational view of the preferred embodiment of'the invention as applied to the surface of a grinding-wheel; and

Figure 3 is a view taken along the line 3-3 of Figure 2, and including a phantom outline of the tool and its holder in another position to illustrate the fact of lateral moveability.

r cussion, is to provide a tandem action dressing device which will perform an improved wheel dressing oper ation comprising the simultaneous application of two spaced'dressing tools in tandem relationship in a plane normal to the axis of the wheel, each tool dressing the same surface path of the rotating wheel. The illustrated wheel 13'rotated upon a shaft 15. Here it will be seen.

tool incorporates a large diamond cluster 14 at the first end 11 and a diamond impregnated section 16 at the second end 12.

In Figure 2, there is shown a portion of a grinding that the large diamond cluster 14 will be in the leading position with respect to engagement of a particular wheel surface portion. The arrow indicates the conventional direction of wheel rotation. If the wheel rotation is otherwise, the position of the spanner is simply reversed. The second diamond impregnated section 16 follows in tandem relationship and in the preferred'method of use dresses the identical path, for all practical purposes, as that dressed by the cluster 14. Thus, a cutting'action may be provided immediately followed by a final; filter dressing action.

The reference character 14 refers to a large diamond cluster, whereas the reference character 16 refers to a diamond impregnated section. pregnated sections are common and usual diamond dressing wheel structures and' are well known. Their relationship and use is. the novel arrangement provided by this invention. It is generally desired to take a considerable amount of clogged and deformed wheel surface off of the wheel first and then give a smooth dressing. It is, of course, entirely possible, and in fact often carried out, that both ends will carry diamond impregnated sections for very fine dressing; Such dual fine dressing is'particularly adapted for hard wheels producing an extremely fine workpiece surface finish. It should be recognized that the illustrated tool and this description is set forth only for the purpose of teaching the basic concept and principles of the invention, and can be modified in detail according to need.

A unique function of this tandem action tool is the ability to close the wheel grain for fine workpiece grinding, as well as to open the grain for fast cutting. It has been found that placing two diamond impregnated tool sections in tandem will not only dress the wheel surface, but will actually compact the surface slightly toprod'uce a very fine finish. It is not fully understood why, but it" is a fact that the finish is notably superior whenever two sections are used in tandem, rather than to repeat twice as often with one section.

To implement and carry out the" full concept of the invention, a carriage adaptor 18 is provided to carry the spanner 10. The carriage adaptor 18 has a stem portion 20 which is insertable into the conventional toolholder of a particular grinder machine, as always-provided; The tool holder is represented. more or less diagrammatically by the portion of such holder 24- set forth in Figure 2. The tool holders are part of the grinding machine and take on various forms. All of them, however, provide for advancement toward and retraction away from the wheel and lateral movement with respect to the wheel, as suggested by double ended arrows in Figures 2 and 3. Any dressing tool, whether the improved invention asset forth herein or a conventional single point tool, may be secured or adapted to be secured by the tool holder 24 and thus moved with respect to the cutting wheel.-

There is sometimes some inaccuracy in tool positioning due to wear or improper provisions in the. tool holder 24 which does not provide a correct approach angle for a single point tool held by theholder 24. This invention overcomes any such inaccuracy and assures a correct approach angle by the provision of coupling the actual working tools, the diamonds, and providing a swivelable interconnection between thecouple and the holder. The stem portion 20 is provided with. aflat surface 21 which may be engaged by a set screw 25 to therefore bring the carriage adapter 18 to a given. preliminary position with respect to the holder 24.

Carriage adaptor 18 is provided with a. track portion 22 having a full body area 27 and areduced body area 29, A curved shoulder 30 is provided between the two body sections and serves as. a back-up track against which the circular C-shaped spanner 10 may rest. Spanner 10 is provided with a slot 31 through which ascrew 32.may be inserted to clamp the spanner 10 to the carriage adaptor 18. In order to cover the slot 31 and. thereby provide a somewhat better appearance, and also avoid damaging the edges of slot 31, a washer 33 may be pro- These clusters and imvided. This screw and the slot 31 permit a degree of pivotal shifting.

The diamond tool industry has long taught that whenever possible the dressing tool should be adjusted with respect to the wheel so that the diamond point drags at an angle of 10 to 15 below a radial line of the grinding wheel with respect to the point of contact of the tool with the wheel. This will prevent chatter and at the same time create a new point on the diamond while wearing out the original point. It is entirely improper to reverse this angle, although it is acceptable and possible to place a tool at a direct nomal' zero lag position if required. It Y may be seen by referring to Figure 2 that this invention provides a built-in self-positioning tool which assures the preferred angle of approach at all times regardless of the setting of the tool. Note that the large diamond cluster 14, as well as the diamond impregnated section 16, in Figure 2, approach at about normal to the center line axis of the wheel 13. An angle may be provided if desired. This positioning may be maintained whether a single diamond point or any particular size diamond cluster is employed. For that matter, although the invention is particularly suited for wheel dressing by diamond tools, it is not necessarily limited to the use of diamond, and any suitable dressing member may be carried at the extremities of the spanner 10 to achieve most of the desired results.

In use, the carriage adaptor 18 is mounted in the holder 24 and the holding screw 32 is loosened slightly. The holder 24 is then advanced slowly until the sections 14 and 16 are in contact with the surface of wheel 13. This operation should be carried out with the wheel 13 stationary. With the two diamond tools thus in contact, the screw 32 may be tightened and forgotten. The tool is thereafter properly positioned to dress the wheel 13 to a complete finished condition without further adjustment or changing.

After backing the holder 24 away from the wheel 13' to separate the diamond sections 14 and 16 from the wheel surface, the wheel is commenced to rotate and thereafter the holder 24 is advanced to bring the diamond sections 14 and 16 close to the surface of the wheel 13. A quick right and left movement of the holder 24 will determine whether the dressing tool will make contact at any place across the surface of the wheel. Thereafter, the holder 24 is advanced slightly and the alternate movement of the holder carried out until contact is made. The holder is then advanced a determined amount to press the diamond sections into the face of the wheel a proper amount for one pass of dressing. Thereafter, the spanner is moved laterally until a cut is made. The pressure upon the spanner 10 will be divided equally between the two ends of the tool without danger of overloading of one or the other.

As thus far described, it will be understood how the tool is constructed in itspreferred embodiment. Obvious modifications maybe made. Furthermore, the use of the tool has been explained sulficiently to enable one skilled in the art to employ the tool;

An important use of this tool is the accurate dressing of a contoured wheel even tothe provision of a sharp corner. The diamond sections-14' and 16, as may best be seen in Figure l, are just as wide as the body of the spanner 10. The diamonds may be incorporated into the side as well as the base of the clusters 14'. Accordingly, the side of the cluster will cut in the same manner that the face Will cut. Therefore, when an edge must be ground square the spanner is run along the sides of the edge as well as along the face to produce the perfect square corner, or any angular relationship desired.

The tandem action is not to be interpreted as a first cut followed by a second. cut.. The leading'tool should and will do the bulk ofthe dressing work. The second or following tool. is a corrective tool to correct any error left by the leading tool. The second tool. may be likened to a filter. This fact is probably the key to the unusual success of this invention. The second tool does cut. All diamonds wear. Therefore, the leading tool will wear and allow some of the load to transfer to the second tool. Thus the filter action. The second tool will soon wear and transfer the cutting action back to the first tool where it belongs.

Further, a cluster is usually preferred for the leading tool, held in a soft matrix. The second tool should be a hard matrix impregnated with small stones. Then the wear has been found to be about equal.

Sometimes it is desired to actually produce a first and second cut. In such case the holder may be tipped and pivoted slightly to allow the leading tool to cut to one depth and the following tool to cut to a second depth. This is an unusual use situation and is not the principal use of the tool.

Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosed of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

I claim:

1. For a grinding machine having an abrasive wheel rotatable in a verticle plane and having a dressing tool holder adapted to carry a dressing tool to and from the wheel as well as laterally with respect thereto, the provision of an improved tandem action dressing tool comprising a substantially C shaped spanner member having first and second extremities with a rigid interconnecting body therebetween, a first diamond dressing tool carried by said spanner at said first extremity, a second diamond dressing tool carried by said spanner at said second extremity, a carriage adaptor having a stem portion and a track portion, said stem portion engageable by said tool holder and having a locating surface establishing a fixed position for the stem portion, means mounting said spanner on said track portion for limited adjustment with respect thereto in a plane, said carriage adaptor establishing said plane along a plane of rotation of the wheel, whereby the spanner may be advanced by the tool holder until both diamonds are engaged with the wheel, to establish the diamonds in spaced positions on a given circle, Whereafter the means mounting the spanner may be tightened and the tandem dresser thereafter employed to dress the wheel with the first and second diamond cutting in tandem relationship.

2. For a grinding machine having an abrasive wheel and having a dressing tool holder adapted to carry a dressing tool to and from the wheel as well as laterally with respect thereto, the provision of an improved tandem action dressing tool comprising a substantially G shaped spanner member having first and second extremities with a rigid interconnecting body therebetween, a first dressing tool carried by said spanner at said first extremity, a carriage adaptor having a stem portion and a swivelable mounting, said stem portion engageable by said tool holder and having a locating surface establishing a fixed position for the stem portion, means mounting said spanner on said swivelable mounting for limited adjustment with respect thereto in a plane, said carriage adaptor establishing said plane along a plane of rotation of the wheel, whereby the spanner may be advanced by the tool holder until both dressing tools are engaged with the wheel, to establish the dressing tools in spaced positions on a given circle, whereafter the means mounting the spanner may be tightened and the tandem dresser thereafter employed to dress the wheel with the first and second dressing tools cutting in tandem relationship.

3. A dressing tool for an abrasive wheel, comprising, a spanner member having first and second extremities, a first wheel dressing tool carried by said spanner at said first extremity, a second wheel dressing tool carried by said spanner at said second extremity, a mounting member adapted to be secured to a tool carrier of a grinding machine, swivelable means mounting said spanner on said mounting member, the distance from said first dressing tool to said swivelable means and the distance from said second dressing tool to said swivelable means being less than the distance between said first and second dressing tools, and means to lock the spanner into a selected position of spanner adjustment.

4. A dressing tool as defined in claim 3, wherein the spanner member is C shaped.

5. A dressing tool for an abrasive wheel, comprising, a spanner member having first and second extremities, a first wheel dressing tool carried by said spanner at said first extremity, a second wheel dressing tool carried by said spanner at said second extremity, a mounting member adapted to be secured to a tool carrier of a grinding machine, adjustable means mounting said spanner on said mounting member at a location approximately equidistant between the first and second dressing tools and at a distance from each tool less than the distance between the tools, said spanner adapted by said adjustable means to establish simultaneous and fixed relative positioning of the first and second dressing tools with respect to said holder and to one another, said relative movement establishing a forward and outward movement of one said dressing tool simultaneously with an identical rearward and inward movement of the other dressing tool, whereby the mounting member may be advanced to a wheel to be dressed and both the firstand second dressing tools swiveled into contact with the wheel surface in tandem dressing relationship, and means to lock the spanner into a selected position of adjustment.

6. The method of performing an improved wheel dressing operation, comprising, mounting a first andv second wheel dressing member on a holder a spaced distance apart and orientated to extend against a common grinding wheel surface, grasping said holder in a swivelable mounting at a location which is spaced from each wheel dressing member a distance less than the said spaced distance between the dressing members, providing said swivelable mounting in a free condition, thereafter moving said mounting location along a fixed path toward a wheel surface until both said wheel dressing members are brought into contact with the wheel surface to be dressed, orientating said first and second wheel dressing member to a tandem position wherein rotation of the wheel will cause a selected wheel area to pass under both wheel dressing members, thereafter locking said swivelable mounting against free movement, and finally thereafter driving said holder along said path against the wheel while rotating the wheel.

References Cited in the file of this patent UNITED STATES PATENTS 1,905,821 Dunbar Apr. 25, 1933 2,254,392 Petrie Sept. 2, 1941 2,395,662 Hoagberg Feb. 26, 1946 2,502,381 Indge Mar. 28, 1950 2,662,519 Metzger Dec. 15, 1953 FOREIGN PATENTS 228,465 Germany Nov. 10, 1910 419,319 Italy Mar. 20, 1947 617,343 Germany Aug. 16, 1935 743,343 Great Britain Jan. 11, 1956

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