US3386212A

US3386212A - Grinding fixture

Info

Publication number: US3386212A
Application number: US508413A
Authority: US
Inventors: Leslie A Lenhard
Original assignee: Leslie A. Lenhard
Current assignee: LESLIE A LENHARD
Priority date: 1965-10-21
Filing date: 1965-10-21
Publication date: 1968-06-04
Anticipated expiration: 1985-06-04

Description

June 4, 1968 L. A. LENHARD 3,386,212

GRINDING FIXTURE Filed Oct, 21, 1965 2 Sheets-Sheet 1 INVENTOR. LESLIE A. LENHARD ATTORNEYS June 4, 1968 Filed Oct. 21, 1965 2 Sheets-Sheet 2 C/l8 l9 L 3| 32 29 I2 24 25 f3 FIG. 3

INVENTOR. LESLIE A. LENHARD ATTORNEYS United States Patent 3,386,212 GRINDING FIXTURE Leslie A. Lenhard, Fairfieid Drive, Brighton, N.Y. 11235 Filed Oct. 21, 1965, Ser. No. 508,413 4 (Ilaims. (Cl. 51-217) ABSTRACT OF THE DISCLOSURE A fixture for squaring blocks has a flat, upright master surface to which a fiat face of a block is clamped, fiat end surfaces accurately perpendicular to the master surface, and a fiat base accurately perpendicular to both the master surface and the end surfaces. The base is formed as spaced-apart feet providing a channel extending under the fixture for receiving the span of a C-clamp for clamping the block to the master surface. A broad inclined plane along the top of the upright body of the fixture supports the fixture in an inverted, canted orientation in which a block can be quickly clamped to the fixture with its top accurately parallel with and extending above the fixture body for grinding. The block is also arranged with an end extending beyond one end of the fixture so that the top and extending end of the block can be accurately squared without unclamping the block. A notch can be formed in an end surface of the upright body to receive an additional C-clamp for greater clampin g security.

This invention resides in the art of work holders. It

- relates to a fixture for a work holder particularly useful in the finishing of squared blocks and the like.

In setting up dies and in other tool and machine work it is common practice to employ squared blocks. These are rectangular blocks of metal, the opposite sides of which are fiat and in parallel planes while the sides thereof that meet are in perpendicular planes. It is important for the sides of squared blocks to be finished as accurately as possible to insure accurate work. Even seemingly insignificant deviations of the sides of squared blocks from parallel or perpendicular planes can be cumulative or additive to produce serious errors when a number of blocks are used together.

Squared blocks are usually finished by grinding. This can be done manually, but it is more practical to finish them with a machine grinder such as an overhead grinder. To obtain accuracy in the machine grinding of squared blocks it is necessary to employ means to hold them while they are being ground.

In squaring a block by a machine grinder, a first side (referred to hereinafter as the back with the opposite side hereinafter being identified as the front) of a substantially rectangular block is ground to accurate flatness. In the case of an overhead grinder this calls for a table with an accurately fiat, horizontal surface and means for producing relative movement between that surface and the grinder in accurately parallel planes. In such case the block is placed on the surface with the back facing up and is held in place by a magnet, chuck or the like during the grinding of the back.

After grinding of the back has been completed, the block is turned 90 and anchored to a special work holder for grinding a second side of the block accurately fiat and accurately perpendicular to the plane of the back. For convenience this second side is hereinafter referred to as the top and its opposite side is hereinafter called the bottom. The remaining two sides are hereinafter termed ends.

Heretofore, the work holder commonly employed for this purpose has comprised a fixture known as an angle 3,33%,212 Patented June 4, 1968 plate. This fixture is formed by two plate-like legs which meet at right angles. The inner and outer sides of each leg are accurately flat and accurately in parallel planes perpendicular to the planes of the inner and outer sides of the other leg. The remainin sides of each leg, herein called the top and ends so as to be consistent with the nomenclature of the block, are likewise accurately fiat .and accurately in planes perpendicular to the planes of the inner and outer sides of that leg.

The block is placed on the angle plate so that the accurately ground back is against the inner surface of a leg (for convenience, called the first leg) of the angle plate with the block projecting beyond the top of this leg substantially the same distance from one end to the opposite end of the block and preferably, if the angle plate is to be used in the third grinding step, projecting beyond one end of the first leg substantially the same distance from the top to the bottom of the block. In the case of a block wherein the general dimension from top to bottom is larger than the dimension of this leg from its to to the other or second leg, the projection of the block beyond the top of the first leg is obtained with ease because the bottom of the block rests on the inner side of the second leg. In the case of a block wherein this general dimension is smaller, a parallel is used. This is a rectangular bar of steel usually having substantially flat, opposite sides that are substantially parallel and spaced from each other to obtain the necessary projection of the block beyond the angle plate. The parallel is laid on its side either on the inner side of the second leg and the block is placed on top of the parallel to obtain the necessary top projection, or, particularly if the general, top to bottom dimension of the block is still too small, the parallel is placed on a horizontal at least substantially fiat, surface, usually the table of the grinder, the angle plate is inverted and the top of the first leg is placed on the parallel. The block with its top on the fiat surface is then moved into position.

Once in position, the block is anchored to the angle plate usually with a C-clamp, one end of which bears against the outer side of the first leg and the other end of which bears against the front of the block with the span or Web of the clamp around one end of the first leg.

The angle plate with the block anchored to it is inverted, placed on the grinder table and secured thereto by a magnet, a chuck or the like. The top of the block is then ground accurately fiat and accurately in a plane perpendicular to the plane of the back of the block.

The next step is to grind one of the ends of the block so that it is accurately fiat and accurately in a plane perpendicular to the planes of the top and back of the block. For this step either a fixture such as the angle plate or a fixture of the kind disclosed in the US. Patent No. 3,155,384, to Schwenzer has heretofore been employed. In the case of the angle plate, the proper position of the block is obtained in one of two Ways. One Way is to repeat the set-up procedure of the second grinding step, but with the end of the block turned up so that it projects beyond the top of the first leg. The other way is followed only if in the set-up procedure of the second grinding step the block was placed on the angle plate with one end of the block projecting from one end of the first leg. In such case, before loosening the C-clamp a second C-clamp is mounted on the angle plate and the block with its span disposed around the top of the first leg of the angle plate. The first C-clamp is removed and the angle plate turned so that the end of the front leg from which the end of the block projects is now up and the other end of the first leg and corresponding end of the second leg of the angle plate rest on the grinder table. The angle plate is then secured to the table as by a magnet or the like. If the angle plate is dimensioned so that the distance from J end to end is greater than the distance from the top of the first leg to the outer side of the second leg, the height of the overhead grinding wheel relative to the grinder table has to be increased. The exposed end of the block is then ground.

The block is removed from the fixture and the remaining end, front and bottom of the block are ground in the same manner as the back.

In the set-up procedure of the third grinding step which, as indicated, has heretofore required placing the block into another fixture or resetting the block in the same fixtureor changing clamps, the position of the block is inevitably disturbed. This introduces inaccuracies.

Moreover, in following these set-up procedures for the entire grinding process an excessive amount of equipment is involved and the procedures are time consuming.

An object of this invention is to provide a fixture which avoids these disadvantages.

More particularly, an object of this invention is to provide a fixture which makes possible the finish grinding of the top and an end of a squared block without to either reclamp, reset or remove the block relative to the fixture between the second and third grinding steps.

A specific object of this invention is to provide a fixture which makes possible simplification of the set-up procedure and equipment requirements for the second grinding step in the finish grinding of squared blocks and the like.

Still another object of this invention is to provide a fixture useful for supporting a squared block and the like, which has a simple, readily made structure.

These and other objects of this invention which may appear as this specification proceeds are achieved by this invention.

In summary and broadly considered, this invention provides a fixture to which a workpiece having an accurately flat first surface can be anchored for the formation thereon of two more surfaces that are accurately fiat and accurately in planes perpendicular to each other and to the plane of said first surface.

According to this invention there are three general embodiments of the fixture. In each embodiment the fixture comprises a body and a base.

The body has an accurately flat surface, hereinafter referred to as the master surface. Its plane is hereinafter referred to as the master plane. When the workpiece is in position on the fixture, the accurately fiat first surface bears against the master surface. The body of the fixture includes another, accurately flat surface. This is accurately in a plane, referred to as the first standard plane, which is perpendicular to the master plane. This surface functions to support the fixture when it is in one position for the finish grinding of a surface on the workpiece anchored to the master surface.

The base of the fixture is generally perpendicular relative to the master surface of the body. It has a fixture support surface which is accurately flat and accurately in a plane, referred to as the second standard plane, which is perpendicular to the master plane and to the first standard plane. In addition, it preferably has an accurately fiat auxiliary support surface accurately in the first standard plane.

In one general embodiment of the fixture at least one of the body and base has an opening for the span of a C- clamp or the like so that the fixture with a workpiece clamped thereto can be turned up on end without having to remove the C-clamp or the like.

In the second general embodiment of the fixture the top of the body has a beveled surface which, after inverting the fixture and tilting it back (relative to the master surface) on the beveled surface, enables a relatively small workpiece such as a relatively small block or the like to be placed into position without having to resort to a parallel to obtain the necessary projection of the workpiece beyond the top of the fixture body.

In the third general embodiment of the fixture the base has a raised surface on which a relatively large workpiece can be supported to project beyond the top of the body of the fixture.

This invention is further described relative to the drawing which forms a material part of the disclosures of this specification. In the drawings:

FIG. 1 is a perspective view of a preferred specific embodiment of the fixture of this invention, which view shows a relatively large, rectangular block in position with a lower portion of the block removed to reveal underlying structure, and further showing a C-clamp mounted on the fixture;

"RIG. 2 is a plan view of the fixture, block and C-clamp combination of FIG. 1;

FIG. 3 is a front elevational view of the sp'ecific embodiment of the fixture of FIG. 1 with the block removed; and

FIG. 4 is a side view of the specific embodiment of the fixture of FIG. 1 in inverted, tilted back position, which view shows a relatively small squared block in position with a C-clamp clamping the block to the fixture.

In greater detail, FIGS. 14 of the drawing illustrate a fixture 10 according to this invention. As shown, it is an integral structure comprising a body 1 1 and a base comprising two

feet

12 and 13.

The body 111 in this embodiment is generally plate-like, having a front, a back, two ends, a top and a bottom which merges into the two feet 1-2 and 13 of the base.

The front of the body 11 comprises an accurately flat surface 15 which is the master surface. In the embodiment shown this surface 15 occupies substantially all the front of the body 111.

The back of the body 11 (see FIGS. 2 and 4) comprises a surface 16 which is substantially fiat and substantially parallel to the master surface 15. The back sur face 16 in the embodiment shown takes up' substantially the entire back of the body 11.

At one end of the body 11, the left end in the embodiment shown, the body 11 has in the region of the top a laterally projecting portion v17 (see FIGS. 1 and 3) which terminates in a fixture support surface 18. This surface is accurately flat and accurately in the first standard plane. When the fixture 10 is turned over on end with the fixture support surface 18 facing downwardly, this surface supports the fixture 10.

The other end of the body v11, shown in FIGS. 2 and 3, comprises a surface 19 which is at least substantially flat and at least substantially in a plane perpendicular to the master plane. While the end surface 19' need not be accurately fiat and accurately in a plane perpendicular to the master plane, under other concepts of this invention it can be. In general, the end surface 19' extends from front to back and from top to bottom of the body 1:1.

The top of the body 11 comprises a beveled surface 20 (see FIGS. 1 and 4) extending from end to end and from the back at least part way to the front. This surface is at least substantially fiat and at least substantially in a plane which intersects the master plane at an acute angle, generally and preferably at an acute angle in a range from about 60 to about In the embodiment illustrated the beveled surface meets along a substantially straight line another surface 21 extending from end to end and from the front backwardly. This second surface of the top is substantially flat and substantially in a plane perpendicular to the master plane.

The

feet

12 and 13 forming the base of the fixture 10 are generally plate-like structures which extend frontwardly and backwardly of the body 11 (see FIGS. 1 and 2). The feet '12 and .13 are laterally spaced apart, whereby there is a longitudinal opening 23 between them for the span of a C-clamp or the like. The foot 12 has a bottom surface 24 and the foot 13 has a bottom surface 25. Both of these surfaces are accurately fiat nd accurately in the same plane. This plane is the second standard plane. One of the

feet

12 and 13, which in the embodimeat shown is the left-hand foot, comprises an accurately flat surface 26 accurately in the first standard plane. This surface 26 functions as an auxiliary support surface for the fixture when it is turned up on end with the surface 18 of the body projection 17 facing downwardly. Between the lateral projection 17 of the body 11 and the top of the underlying foot -12 is an opening or end recess 27 for the span of a C-clamp or the like. At the other end of the fixture 10 the other foot 13, which in the embodiment shown is the right-hand foot, comprises an at least substantially fiat surface 29 at least substantially in the plane of the corresponding end surface 19 of the body ti l.

On top of the

feet

12 and 13 and adjacent to the front of the body 11 are steps or

shoulders

31 and 32. The tops of these

steps

31 and 32 comprise

surfaces

33 and 34 which are at least substantially flat and at least substantially in the same plane with that plane being perpendicular to the master plane. Of course, under the concepts of this invention, the

surfaces

33 and 34 of the steps can be accurately flat and accurately in a plane perpendicular to the master plane.

The fixture is particularly useful in the finishing of two perpendicular sides of a squared block. A full size -(relative to the fixture 10) squared block is illustrated in FIGS. 1 and 2. It is a rectangular block of metal comprising six sides which, for convenience, are identified as they appear in FIG. 1. Thus, the squared block 40 comprises a front 41, a top 42, a back 43, a bottom 44, a left end and a right end 46. Before the block 40 is mounted on the fixture 10, one side, in this instance the back 43, preferably is ground accurately flat. Thereafter block 40 is placed into position relative to the fixture '10. In position the accurately flat back 43 of the block 40 bears against the master surface 15 of the fixture 10 while the bottom 44 rests on the

steps

31 and 32 of the

feet

12 and 13. In addition, the block projects substantially equidistantly from one end to the other above the top of the body 111 (see FIG. 1) and projects beyond the right-hand end of the body 11 (see FIG. 2) substantially equidistantly from top to bottom.

With the block 40 properly situated relative to the fixture 10 a C-clamp 48 having a base 49 (see FIG. 2) a head 50 and a span 51 (see FIG. 1) is placed into position. In this connection, the span or web 51 of the clamp 48 is disposed in the space 23 between the

feet

12 and 13 as in FIG. 1 or in the end recess 27 between the lateral projection 17 of the body 11 and the foot 12. Both openings are of size and shape sufficient to accommodate the span 51 so that in the case of the end recess 27, the span 51 does not extend beyond the first standard plane, and in the case of the opening 23 between the

feet

12 and 13, the span 51 does not extend beyond the second standard plane. In the case of the opening 23 between the

feet

12 and 13, it can also pass through the lower portion of the body 11 as illustrated in FIGS. 1 and 3. The base 49 of the clamp 48 bears against the back 16 of the body 11 while the head 50 bears against the front 41 of the block 40.

It can also be in reverse order. The fixture with block 40 and clamp 48 thereon is anchored to the table of an overhead grinder and the top 42 of the block is ground to an accurately flat surface. Because of the fixture 10, this surface is accurately in a plane perpendicular to the plane of the back 43 of the block 40.

The fixture 10 is then turned on to its left-hand end so that the first standard surface 18 of the body 11 and the auxiliary support surface 26 of the foot 12 are on the table of the overhead grinder.

The right-hand end 46 of the block 40 is ground to an accurately flat surface. The accurately flat surface thus obtained is, because of the fixture 10, accurately in a plane perpendicular to the planes of the back 43 and top 42 of the block 40.

The block 40 is removed from the fixture 10' and the remaining front 41, bottom 44 and left end 45, made accurately fiat by placing the corresponding accurately flat parallel sides face down on the table of the overhead grinder and grinding the respective remaining sides. The resulting block 40 is a squared block.

In the case of a rectangular block which is small compared to the fixture 10, such as the block 60 in FIG. 4, the back 63 thereof is preferably first ground to accurate flatness and then the block is placed into position relative to the fixture 10. To do this, the fixture 10 is inverted and tilted back so that the beveled top surface 20 of the body 11 rests on a substantially fiat surface 54 as in FIG. 4. The block is placed so that its back 63 is against the master surface 15 of the fixture with the edge of the block 60 between its top and back 63 resting on the flat surface 54 and with the right-hand (when the fixture is on its feet 12 and 13) end 66 of the block 60 projecting beyond the right-hand end of the body 11. In this position the block 60 projects beyond the top of the body 11 substantially equidistantly from end to end and beyond the end of the body 11 substantially equidistantly from top to bottom.

A C-clamp 48 is then applied to clamp the relatively small block 60 to the fixture 10. Again, the span 51 of the clamp is disposed either in the opening 23 between the

feet

12 and 13, as shown in FIG. 4, or in the recess 27 between the lateral projection 17 of the body 11 and the foot 12. The fixture 10 is then turned over on its

feet

12 and 13, and the top 62 of the block 6% ground to an accurately fiat surface. Thereafter, the fixture 10 is turned on to its left-hand end so that the first standard surface 18 rests on the table of the overhead grinder, and the right end 66 of the block 60 is ground to an accurately flat surface. Thus the top 62 and the end 66 of the block 60 are made accurately flat and accurately in planes perpendicular to each other and to the plane of the back 63. The block 60 is then removed from the fixture 10 and the remaining unfinished sides ground to accurately flat surfaces by the same procedure for the relatively full sized block 40'.

Preferably, the distance from the end surface 18 of the body 11 to the opposite end surface 19 of the body 11 is substantially the same as the distance from the bottom surface 24 of the foot 12 to the top surface 21 of the body 11. A reason for this is that in finishing blocks that are square and blocks that from end to end are at most slightly larger than the body from end to end, upon turning the fixture 10 from its feet to one end, the relative height of the overhead grinder need not be adjusted to any major extent.

An advantage of the specific embodiment of the drawing is that once the block has been mounted on the fixture, two accurately fiat surfaces in the perpendicular planes can be finish ground without having to reset the block or even to reclamp the block between grindings.

Another advantage of the specific embodiment illustrated is that blocks can be readily positioned thereon, regardless of whether they be full size relative to the fixture or less than full size. This is made possible by the beveled surface 20 at the top of the fixture, and by the

steps

31 and 32.

Still another advantage of the specific embodiment illustrated is that it is stable in both grinding positions; when resting on a substantially flat, horizontal surface, it does not tend to fall over in either position.

Other features, advantages, and specific embodiments of this invention will become readily apparent to those in the exercise of ordinary skill in the art after reading the foregoing disclosures. All such specific embodiments are within the scope of the claimed subject matter, unless expressly excluded by claim language. Moreover, while a specific embodiment of this invention has been described herein in considerable detail, variations and modifications of this embodiment can be effected without departing from the spirit and scope of the invention as disclosed and claimed.

I claim:

1. A fixture for supporting a workpiece that has an accurately fiat first surface, so that two more surfaces that are accurately flat and accurately in planes perpendicular to each other and to the plane of said face surface can be formed on said workpiece without moving said workpiece relative to said fixture, which comprises in upright orientation:

(a) an upright, generally rectangular, plate-like body having a front, a back, a top, a bottom, and an end;

(b) said front of said body comprising an accurately fiat master surface against which said workpiece is placed with said first surface bearing against said master surface;

(c) said end of said body comprising an accurately flat first standard surface accurately perpendicular to said master surface for supporting said fixture when in one position;

(d) said back of said body comprising a generally flat, clamping surface for receiving one jaw of a C-clarnp spanning said body and said workpiece;

(e) a base for said body comprising a pair of spacedapart feet formed as solid plates joined to the bottom of said body and extending below said body and forwardly of said front of said body;

(f) the bottoms of said foot plates forming fixture sup port surfaces that are accurately fiat and accurately in the same plane, which plane is perpendicular to the planes of said master and first standard surfaces; and

(g) said foot plates being spaced apart throughout their length by a distance greater than the thickness of said C-clamp to provide an unobstructed longitudinal opening through the forward end of said feet rearwardly of said back surface and said foot plates supporting said body above the bottoms of said foot plates by a distance greater than the thickness of said C-clamp so that said C-clamp can be inserted in said opening between said feet and under said body to engage said workpiece and said clamping surface for securing said workpiece to said master surface.

2. The fixture of claim 1 wherein said first standard surface is formed to define a recess for wholly receiving the span of another C-clamp spanning said workpiece and said body.

3. The fixture of claim 1 wherein said top of said body is formed to define a relatively broad, plane, support surface extending from a line parallel to said master surface slightly downwardly into communication with said back of said body and lying in a plane oblique to said master surface, said support surface being oriented so that said fixture can be inverted and rested in equilibrium on said support surface while a workpiece is clamped to said fix ture.

4. The fixture of claim 3 wherein said first standard surface is formed to define a recess for wholly receiving the span of another C-clarnp spanning said workpiece and said body.

References Cited UNITED STATES PATENTS 2,595,950 5/195'2 Keebler 51220 2,362,306 11/ 1944 Ringzelli 51220 2,692,462 10/1954 Robertson 512 1.7 2,882,656 4/1959 Novkov 51--217 2,995,962 8/1961 Dietz 51216 X 3,155,384 11/1964 SchWenZer 269101 HAROLD D. WHITEHEAD, Primary Examiner.