US2336506A - Surface plate - Google Patents

Description

H. E.-SAUNDERS SURFACE PLATE Filed Nov. 30, 1942 Dec. 14, 1943.

2 Sheets-Sheet 1 FIG. 2"

INVENTOR. HAROLD E. SAUNDERS BY I \ HIS ATTORNEY.

Dec. 14, 1943. H. E. SAUNDERS 2,336,506

SURFACE PLATE IN VEN TOR. HAROLD E. SAUNDERS S ATTORNEY Patented Dec. 14, 1943 SURFACE PLATE Harold E. Saunders, United States Navy, Takoma Park, Md.

Application November 30, 1942, Serial No. 467,479

1 Claim.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) Specifically, th s invention is a surface plate such as is used in machine shops for precise layout work; it may also properly be termed a layout table. As will be apparent from the following description and claim, however, the invention is not limited to such servce, but will be useful wherever an accurate and substantially distortion-proof surface or structural member is needed.

Most layout tables now in use consist of a working surface, with supporting ribs therefor, and without any lower surface. Such a table may be satisfactory for some purposes and for l mited periods, but it is not distortion-proof under heavy loads, and even under conditions of reasonable use, its life as a precision instrument is relatively short. The invention herein described provides a table in the nature of a box, in that it comprises, in addition to a top surface and a novel arrangement of supporting ribs, a lower surface and side and end surfaces. Further, since it is believed that the deficiencies of prior art structures are due not only to the absence of a lower flange, but also in some measure to a general lack of symmetry which prevents complete distribution of stresses, in this inventic-n symmetry is carefully maintained.

One object of the invention is, therefore, the production of a structural member including a continuous surface of great rigidity.

Another object is the production of a distortion-resistant member comprising two substantially continuous parallel surfaces and a system of interrupted webs therebetween.

It is an object, also, of the invention to produce a member of the nature described wherein the web structure is substantially symmetrical about a plane parallel to the surfaces mentioned and midway between them.

Other objects will appear from a reading of the specification and claim.

In the drawings:

Figure 1 is a top View, partly in section, of a portion of the surface plate of my invention, lustrating one type of internal web structure;

Figure 2 is an end View, also partly in section, of the surface plate of Figure 1;

Figure 3 is a perspective view of a portion of the surface plate of Figure 1 with the exterior thereof broken away at one point to show the web structure;

Figure 4 is a bottom view of a portion of a somewhat modified form of the invention;

Figure 5 is a section taken on the line 5-5 of Figure 4; and

Figure 6 is a perspective view of one corner of the surface plate of Figures 4 and 5, with the exterior surface broken away somewhat.

Referring to Figures 1, 2 and 3 of the drawings, I0 is the top or working surface of the layout table, and H is the lower surface. Joining the spaced surfaces are the side plates I-2 and I3, and end plates, only one of which, [4, can be seen in the drawings. Thev other end plate may be assumed to be identicalwith plate 14.

While the members In, H, l2, l3 and I4 have been, and may hereafter be, referred to for convenience as elements, in the preferred mode of construction, the layout table is a unitary casting and is not made up of separate members secured together.

It will be understood, also, that while the upper surface It has been termed the working surface, the member fl is fundamentally just as well suited to the contemplated use, but since the working surface must be ground and finished to very close tolerances, usually only one surface is prepared for layout work.

symmetrically arranged between the surfaces It! and H are supporting webs which are in the nature of interrupted vertical walls, but which may be described better as comprising columnlike members 28 (Figure 1), consisting of four arms 2i, 22, 23 and 24, with adjacent arms of adjacent columns connected together by relatively low stiffening ribs 25 (above) and 26 (below). The arms 2!, 22, 23 and 24 are preferably rounded off somewhat, as at 21, and the ribs 25 and 25 are similarly rounded, as at 28 (Figure 3).

It will be seen that the so-called side plates and end plates of the structure of Figures 1, 2 and 3 are merely portions of the columns 29 and the connecting ribs 25 and 26. The columns 20 at the corners of the table, in other words, have but two arms instead of the more usual four, and the columns otherwise around the perimeter of the structure have three arms. Further, while the two edgewise arms of each of the edge columns, as arms 21 and 23 at the bottom of Figrespectively. The opposite side and end surfaces are not shown, but are like 42 and 43. The top, side and end surfaces of this embodiment are continuous; the lower surface is substantially so, but if the structure is to be cast, occasional openings, as 50, must be provided for the removal of the cores.

The area between the surfaces 4:: and 4! is divided into smaller areas by means of continuous webs, as 44 and 45. Each of these smaller areas contains interrupted Webs 41, all of these latter webs being substantially identical (Figures 5 and 6). As will be seen from Figure 5, each web 41 is approximately semicircular in shape; preferably, it is in the form of two separate arcs, one extending from the upper surface 40 to a point midway between the top and bottom surfaces on a continuous web 44, 45 or a side or end surface 42, 43, and the other extending from said point toward the lower surface 4|. In a cast structure (as shown), this latter are will not quite reach the lower surface, but will terminate in a low rib 48 surrounding an opening 59.

It is desirable to provide fillets, as 51 (Figures 5 and 6), wherever the webs contact another web or an outer surface.

It will be seen that the sides and ends of the layout table of this invention are not only strengthening members for the upper and lower surfaces, but that they are themselves supported as thoroughly by the internal web structure as are the upper and lower members and in much the same manner. They are, therefore, likewise distortion-resistant. All or some of them are finished as carefully as the upper member, and are useful in providing true 90 angles at and near the boundary of the table. Their depth makes it possible to secure a solid vertical for angle measurement.

The foregoing description is in specific terms. Many modifications will occur to those skilled in the art, and it is therefore to be understood that the invention is not limited to the forms above described, but includes all that properly fall within the scope of the appended claim.

The invention herein described may be manufactured and/ or used by or for the Government of the United States for governmental purposes without the payment of any royalty thereon or therefor.

I claim:

A distortion-resistant member comprising an upper surface, a lower surface and side surfaces, internal webs connecting the said surfaces and perpendicular thereto, said webs subdividing the member into cells of like size symmetrically arranged in rows longitudinally and transversely of the member, said webs supporting relatively small, uniform rectangular areas of said surfaces and tending to equalize any differences in temperature between cells, and interconnected ribs extending along the interior surfaces of said cells in uniformly spaced parallel relation to said webs, said ribs reinforcing said cells and tending to equalize any differences in temperature within the cells.

HAROLD E. SAUNDERS.

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