US2019677A - Surface grinder - Google Patents

Description

NW. 5, 1935. G. Tl HUXFORD SURFACE GRINDER Filed Aug. 25, 1954 2 Sheets-Sheet 1 INVENTQR If? T Hay/0rd m. 5, 1935. V e. T. HUXFORD 2,019,611?

SURFACE GRINDER Filed Aug. 25, 1934 2 Sheets-Sheet 2 INVENTOR 600176: T Huxford Patented Nov. 5, 1935 UNITED STATES SURFACE. GRINIIPER George T. Huxford, Providence, R. I., assignor to Builders Iron Foundry, Providence, R. L, acorporation of Rhode llsland Application August 25, 1934, Serial'No. 741,424

10 Claims.

My invention relates to improvements in sur face grinders where plane surfaces are to be created by grinding. My invention is particularly applicable where one side of the work is to be ground truly plane and parallel with another.

One object of my invention is to provide a single guided work table as the only moving part between the grinding wheel and the bed to thus give an excellence of and trueness of plane not otherwise approached in my experience. Further objects of, my invention are to provide inherently' simple and inexpensive means for accomplishing precision grinding. Suitable reciprocating and traversing means cooperate with my unitary work table to the above ends.

I. am aware that others have provided separate and multiple ways and tables for reciprocating and traversing the work relative to the tool in a surface grinder. These ordinarily require four pairs of V-ways making eight surfaces that must be properly related to produce an even approximately fiat surface. The oil films separating such ways 'vary in thickness linearly due primarily to temperature, oil used and also for other causes. Thus my invention, involving only one oil film, is far superior to other arrangements that have a number of oil films disposed one above another. I believe that my invention provides a unique and novel combination of a unitary table operating on a plane bed with the necessary cooperating means for accurately grinding flat surfaces.

I employ, in fact, a basically new method of grinding a fiat surface on work: that of reciprocating and traversing the work on a unitary table in a guided path between a grinding wheel and a point on a plane surface on the bed directly beneath this wheel. These separated portions are held rigidly by the bed that acts in the same manner as the bow frame of a micrometer. The table and work are moved over the surface of the bed that has been ground smooth and accurately plane. The cost of grinding such a surface is far less than that necessary for the manufacture of the eight ways, previously referred to, that have to be laboriously scraped in by hand to obtain any acceptable degree of accuracy. The under surface of the table has previously been ground smooth and accurately plane. By grinding the platen of the table in position, I am able to achieve even greater accuracy of parallelism of finish of the work than I have found possible otherwise. The above micrometer method of grinding plane and parallel surfaces, I believe to be new and most advantageous in attaining my object of securing the finest finish at minimum expense.

' Another object of my invention is to provide such a grinder with suitable means and methods of eliminating all play that might in. any way stood from a. description. of the preferred. em- 5.

bodiment thereof that. is. illustrated in the. accompanying drawings.

In the drawings, Fig. 1 is. a somewhat diagrammatic, perspective. view of my invention, with the table and its apron partially shown in section.

Fig. 2 is a plan view of my preferred embodiment showing particularly the traversing means and parallel motion linkage for guiding the table in its reciprocations. V

Fig. 3 is a front elevation of my invention with the play-eliminating wheel mounting. clearly shown, and the table and its reciprocating means partially shown in section alongv line 3--3 of Fig. 2.

As shown in Fig. 1,, the work I is suitably at- 'tached to table 2. that. lies beneath wheel 3 on bed l of the grinder. I provide means 5 for manually reciprocating table 2 alternately to the right and left in. a horizontal plane to grind a narrow ribbon surface of length L. I also provide manually operable means 6 for traversing table 2 as required to grind a surface having width W. Wheel feeding means 1 is manually operable to alter the distance T (thickness) between wheel 3 and point as. directly beneath it on the horizontal, plane top surface 8 of the bed 4. The bottom surface 9 of table 2 is ground flat and preferably in the form of a rectangular frame considerably smaller than the outside of the overhanging apron 2a of table 2. As before mentioned, the platen surface Ill is ground, in position, accurately fiat and parallel on the top surface of the table 2.. -Where parallel surfaces are to be ground on the work, I preferably use the following method: The operator mounts the work on the. table with one such surface held against the platen while the opposite side is ground, and then the work is turned over and mounted so that its thus ground surface is against the platen while .its other surface. is ground as before described.

Play removing means! I is provided, as on the spindle l2 of the grinding wheel" 3. I provide clamping means [3 for most rigidly securing the wheel mounting l i to the column I5 carrying handwheel means It for vertically moving the whole mounting l4. This is in addition tothe micrometer-type vertical feeding means 1 above. Power means ll, preferably comprising an electric motor, is provided for driving wheel 3 at substantially constant speed.

The operation of the preferred embodiment of my invention, thus far described, is as follows: Grinding wheel 3 is rotated continuously by power means ll. The work I is suitably mounted, as secured by means of the clamps shown diagram- 60 matically on table 2. These are then reciprocated on the horizontal top plane surface 8 of bed 4 lengthwise through an extent L by manually operating the means 5 therefor. This operation grinds a flat ribbon surface on the top of the work i. The table is then traversed by manual ly operating means 6 to grind an adjacent ribbon surface upon the following reciprocation; this operation being repeated to generate a fiat surface of width W and length L. Whenever required, as following truing of the wheel 3 or for removal of more stock, the wheel feeding means 1 is operated manually to obtain the desired thickness T of the work I and table 2, and hence to secure the proper thickness tof the work itself, the table having constant thickness 15' since the bot-- tom and top surfaces 9 and I respectively of table 2 have been previouslyground flat and parallel. It is thus apparent that I have provided a unitary table for a surface grinder that is simply reciprocated in a guided path and traversed on a plane surface, with the great gain in accuracy that results from this new means and method of operation. A broadly new method is to grind work by horizontally moving a guided unitary table between a plane and a wheel rigidly mounted over a single point in said plane sothat the lowest portion of the wheel truly generates a surface having a. superiority of finish unapproached by following other methods of grinding of which I am aware.

As shown in Fig. 2, the traversing means 6 comprises a handwheel l8 pinned to the screw l9 that is free to turn in its journal 29 but not move longitudinally therein. An internally threaded sleeve 2! acts as a nut for the screw rod l9, and is externally slotted at 22 so that a coacting key 23 permits it to move only longitudinally, i. e. without rotation, through its two guiding bearings 24. These bearings are closely fitted to the outside of the sleeve so as to permit the minimum play consistent with smooth action. oscillatably, but not longitudinally, movable on this sleeve is the link 25 having bearings 26 therefor, one of which contains guide pin 28 coacting with ring groove 29 on the outside of sleeve 2|. At the other end of this link 25 are two conical pins 30 coacting with suitable holes in another, generally similar, link 3! that is similarly, in general, connected with the table by two conical pins 30. However I preferably provide vertical slot 30 in the table for pin 33 so that any accidental departure from true parallelism of the axes of the links connections can not tend to tip the table. I preferably have the axes of each pair of the conical pins 3i] coincident and parallel to those of the other pair and to that of the sleeve 2! so that any point of the table 2 is free to move only in a line on plane surface 9 on top of the bed 4. This line of reciprocation can be altered by turning the screw I9 as will hereinafter be described.

The operation of this parallel link guiding and traversing means 6 is as follows: The operator turns handwheel [B to move the table forward or back to bring the work to the desired position relative to the wheel. Upon reciprocating the table, the parallel links 25 and 3| connecting it with the sleeve 2| act as double hinges andso constrain it to move in the line determined by the axial position of the sleeve upon the screw l9. This hinge action does not alter the axial position of the sleeve since the sleeve is prevented from turning by its slot 22 and coacting key 23.

The reciprocating means consists of the link 32 oscillatably attached to table 2 by pin 33 at one end thereof. Pin 33 at the other end of this link 32 similarly attaches it to the middle portion of horizontal lever 34 that is oscillatably secured at one end by vertical pin 35 to the bed 4 5 and has the other end adapted to form a handle suitable for manual operation. The operation of this simple reciprocating means is obvious from the drawings and above description.

In Fig. 2 is also shown the preferred means that I use in eliminating play from the spindle l2 for the grinding wheel 3. This comprises conical bearing 36 at one end of the spindle l2 and the ballbearing 3! at the other end thereof, with spring 38 adapted to move the spindle endwise in the conical bearing 36 to remove all play therefrom. Pulleys 39, respectively mounted on spindle I2 and the shaft of the motor H, are operatively connected by belt 40.

In Fig. 3, the hinge action of the guiding links and 3| for table 2 is apparent, as is the recessed underneath form of table 2. The method and means used in rigidly mounting the wheel 3 Fig. 1. Motor I1 is oscillatably mounted on shaft 43 that is pinned to the frame 4| to act as a counterweight therefor. Wheel feeding means I is provided with cooperating micrometer scales 44 to permit of fineness of feed. The screw 45 of this feeding means 1 is abutted by the frame 4| under the above mentioned counterweighting action of the motor I1. Stops 8b are provided to limit the extent of reciprocation of table 2. The column l5 and traversing screws journal 20 similarly limit the extent of traverse of the table.

The operation of the above described portion of my invention in removing play is as follows: The operator moves the entire wheel mounting I4 to the proper height for the work i. Clamping 7 means l3 is then tightened, thus rigidly securing the wheel mounting assembly l4 to the column I5. The wheel is then lowered by the Vernier feed I through a distance read on cooperating scales 44. The counterweight action of motor I! keeps the frame 4! tight against the lower end of micrometer screw 45 so that no play exists. The same weight removes the slack from the belt 48. Thus while grinding, the wheel pressure merely increases slightly the amount of compression of members that are already in compression; there being no reversal of forces and hence no possibility of inaccuracy due to play.

It is apparent from the foregoing that I have provided an improved method of, and means for, generating a ground surface. I am aware that, in times past, others have moved work on a plane surface under a grinding wheel spaced therefrom. However, the work frequently has no portion opposite the ground surface suited for sliding on the guiding plane surface, the grit from the wheel falls onto and abrades the guiding surface. and inaccurate and unsuitable finish results where no guiding means is provided for the work in its reciprocations. In practice, this crude method has utterly failed to achieve the results obtained with my invention. I believe that I am the first to provide means for, and methods of, guiding work held on a suitable unitary table over a plane surface, this table having an apron to protect said plane surface,

so as to obtain the full accuracy and fineness of finish that can thus be achieved. My invention is not confined to the grinding of flat surfaces, e. g. being equally useful in the generation of spherical surfaces. It is further not confined to grinding but can. be used with any method of removing material from work to generate a smooth, regular surface.

While I have described and illustrated the preferred embodiment of .my invention, it is to be understood that I am not to be limited thereby, and that the scope of my invention is defined by the claims appended hereinafter. For example, a slotted guide frame might readily be substituted for the parallel link means I have shown for constraining the table in its reciprocations.

I claim:

1. In a surface grinder, the combination of a single guiding surface, a grinding wheel, means to space said wheel a predetermined distance from said surface, a table adapted to hold work and slide upon said surface to bring said work into operative relationship with said wheel, means for reciprocating said table relative to said wheel, means for guiding said table in its reciprocations to constrain it within a predetermined path, and traversing means for altering said path.

2. In a surface grinder, the combination of a single plane guiding surface, a grinding wheel, means to space said wheel from said surface, a table adapted to hold work and slide upon said surface to bringsaid work and said wheel into operative relationship, means for reciprocating said table relative to said wheel, means for guiding said table in its reciprocations to constrain it to move along a predetermined straight line parallel to said plane surface, and traversing means for altering the position of said line parallel to its preceding position and to said plane.

3. In a surface grinder, the combination of a guiding surface, a grinding wheel, means to space said wheel from said surface, a table adapted to hold work and slide upon said surface to bring said work into operative relationship with said so proportioned relative to each other and saidextents of reciprocation and traversing that said apron at all times covers all portions of said guiding surface that are contactable by said table bearing surface within its limited extents of movement.

4. In a surface grinder, the combination of a bed having a single plane guiding surface thereon, and a work-carrying table adapted to bear upon and slide over said surface substantially as described, said table having a portion adapted to act as an apron to cover the extent of said surface contactable by the bearing portion of said table in its sliding movements over said surface.

5. In a surface grinder, the combination of a single guiding surface, a grinding wheel, means to space said wheel from said surface, and a table adapted to hold work and slide upon said surface to bring said work into operative relationship with said wheel, said means being constructed and arranged so that all forces acting on said spacing means act in the same direction when the work is being acted upon by said grinding wheel as when it is not.

6. In a surface grinder, the combination of a bed; a plane guiding surface thereon; a grinding wheel; means to space said wheel from said surface; a table adapted to hold work and slide upon said surface to bring said work into operative relationship with said wheel; means for recipro- 1 cating said table relative to said wheel; means for guiding said table in its reciprocations to constrain it to move in a predetermined line, comprising a parallel link motion including two links, and means hingedly connecting without play, said links together, to said table and to an axis oscillatably mounted in said bed, said connections being substantially parallel to each other and said axis; and traversing means coacting with said table reciprocation guiding 2 means.

7. In a surface grinder having a parallel link motion substantially as specified in claim 6, one of said means connecting one of said links to said table being adapted to move unrestrainedly rela- 2 tive to said table in a direction normal to said guiding surface, and constraining said table only in directions parallel to said guiding surface regardless of any accidental departure from true parallelism of said links. 3

8. In a surface grinder as in claim 6, said traversing means comprising a manually operable screw, a sleeve nut for said screw, means to constrain said screw to move only in rotation, means to constrain said sleeve to move only 3 translationally along its axis, and means connecting said parallel link motion with said sleeve and adapted to permit said links to move oscillatably but not translationally thereof.

9. In a surface grinder for generating smooth 4 surfaces, the combination of a single smooth guiding surface, a motor, a grinding wheel operatively connected thereto; a spindle for said Wheel; bearing means for rotatably mounting said spindle without endor side-play; structural means attached to said guiding surface, and a frame adapted to hold said bearing mounting means and said motor, said frame being pivotally mounted on said structural means and having said motor so disposed that its weight 50 positively forces said frame to abut a portion of said structural means, said abutted portion comprising means adjustable to alter the spacing of said grinding wheel from said guiding surface.

10. The method of generating a smooth plane surface on work parallel to that on the opposite side that comprises passing a table over a plane surface and underneath a grinding wheel spaced therefrom, reciprocating said table in a constrained predetermined path over said plane 6 surface to grind a ribbon surface-plane in the direction of its length and substantially plane in the direction of its width, and altering said path to cause adjacent ribbon surfaces to overlap .and so form a smooth platen plane in the directions of both length and width, mounting the work thereon with one surface held against said tables platen and repeating said above grinding operation on the side of the work then toward the wheel, and subsequently turning the work 7 over and repeating the above grinding operation so that both sides are truly smooth, plane and parallel.

GEORGE T. I-IUXFORD.

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