US2075546A - Apertured structural elements and machine parts - Google Patents

Description

F. RINAGL Filed Nov. 2e, 1955 APERTURED STRUCTURAL ELEMENTS AND MACHINE PARTS March 30,Y 1937.

Patented Mar. 30, 1937 UNITED STATES APERTURED STRUCTURAL ELEMENTS AND MACHINE PARTS Franz Rinagl,

Vienna, Austria Application November 26, 1935, Serial No. 51,705

In Austria 6 Claims.

The frequently necessary provision of apertures, drilled holes, and the like in machine parts and structural elements of all kinds is of detrimental effect when these parts and elements are subjected to stress by external forces not only on account of the reduction in crosssection involved, but also in a special sense owing to the fact that the distribution of the lines of force becomes altered and ceases to be uniform over the remaining cross-section of the material, with consequent increased stressing of the material in the immediate vicinity of the apertures.

It has been found that longitudinal apertures of elliptical or oval shape disposed with their longitudinal axis parallel to the lines of force o result in less irregularity in the distribution of tension than apertures of round shape or apertures disposed with their largest dimension transversely to the main run of the lines of force. However, the circular shape is very much favoured and is often indispensable for apertures in structural parts, and that partly for reasons of manufacture and partly on account of the necessity of providing for articulate movement between the parts concerned and other parts associated therewith by means of the apertures.

The present invention has for its object, by suitable construction or" the structural parts or elements in the vicinity of the apertures, to effeet a similarly favourable deflection of the lines r of force and distribution of tension in the crosssections weakened by the apertures as is obtained with the use oi longitudinal apertures disposed in the direction of the lines of force.

With this object in View, the invention consists essentially in providing, fore and aft of the apertures in the direction of the lines of force, interruptions in the continuity of the material of the parts or elements concerned in the form for example of additional apertures, slots, or bodies of inlaid or inserted foreign material, these interruptions being so shaped as to gradually divert the lines of force about the primary aperture. In this manner crowding of the lines of force in the immediate vicinity of the aperture is avoided, and the lines of force become as nearly as possible uniformly distributed over the Whole of the available cross-section.

Forms of construction illustrative of the principle of the invention are shown, by way of example, in the accompanying drawing, in Which:-

July 24, 1935 (Cl. 18S- 34) Figs. l, 2, and 3 show rod-shaped perforated structural elements with interruptions in the continuity of the material in the vicinity of` the apertures in accordance with the invention, showing the trend of the lines of force Within the rod when subjected to tensile strain in a longitudinal direction.

Fig. 4 shows, by Way of comparison, the disposition of the lines of force in a similarly strained rod provided merely with a round hole.

Figs. 5 and 6 show the perforated club-shaped end of a rodY subjected to tensile strain, with and without the constructional features according to the invention for the gradual deflection of the lines of force, respectively.

Referring to Fig. 1, a round hole is drilled in the rod l, say for the attachment of some further structural element in circumstances in which no great force is to be transmitted through the attaching bolt. On both sides of the hole Y2, in the longitudinal direction of the rod there is provided a slot 3 cut in the rod. These slots are of semi-oval shape with the closed ends nearest the hole 2 and tapering in the direction away from the latter. The maximum breadth of these semi-oval cuts, measured in a direction normal to the longitudinal axis of the rod, 4is smaller than or at the most equal `to the diameter of the hole 2. The slots 3 can be produced by starting from small holes drilled at the prospective ends, as indicated at 4, and cutting by means of a saw or of a fusing burner.

Instead of the described oval slots, further and smaller apertures can also be provided on both sides of the primary aperture 2, as shown in Fig. 2. In the simplest form of construction these apertures can be circular drilled holes 5, but they can also be of oval or semi-oval shape adapted to the desired deflection of the lines of force in the material of the part concerned,`m.ore particularly in the case of the supplementary holes 6 most remote from the primary aperture 2. The inside clearance of the supplementary apertures 5, 6 diminishes with the distance from the primary aperture 2 in both directions. The simplest arrangement from the manufacturing point of View` is to provide one circular hole of smaller diameter on each side of the primary aperture, as indicated at 'l in Fig. 3. If desired, the supplementary apertures can be connected together and to the primary aperture by longitudinal slots. The mere provision of a longitudinal slot alone on either side of the primary aperture lengthwise of the structural part or element concerned will also eilect an improvement in resistance to strain in the sense implied by the present invention. Finally, such longitudinal slots can also be replaced by rows of holes of a diameter approximately equal to the breadth of the slots.

When subjected to tensile stress, rods constructed in the manner described and illustrated present the lines of force pictures represented in the drawing, from which it will be seen that the lines of force are gradually deected by the slots or holes 5, 6, l, so that they are fairly uniformly distributed over the critical cross-section adjacent the primary aperture 21. Fig. 4 shows, by way of comparison, the lines of force in an otherwise similarly apertured and stressed rod which is not constructed in the manner prescribed by the present invention for the protection of the critical cross-section. In this case the lines of force only become deflected in the immediate vicinity of the primary aperture 2, and thus become considerably denser close around this aperture than in the remainder of the cross-section of the rod. The rod is thus more heavily stressed at the parts 8 at the sides of the aperture. The arrangement according to the invention, by bringing about uniform distribution of the lines of force over the critical cross-section adjacent the aperture, increases the strength of the rod and endoWs it with greater resistance to tensile stress. A similar increase in resistance is also obtained When the rods are subjected to compressing stress.

The principle of the invention is applicable not only in cases of the above-described type but also When the forces applied to the rod are to be directly transmitted to a bolt or pin supported in the aperture 2, more particularly in the case of tractive force. Thus, for example, Fig. 5 Shows a link or eyelet rod coacting with a pin 9 under tensile stress, and provided, in accordance with the invention, with a longitudinal oval slot I0 in front of the eyelet. The picture of the distribution of the lines of force, compared with that of an ordinary tension link rod as shown in Fig. 6, shows the advantageous effect of the arrangement according to the invention.

In order to prevent the inside surfaces of the Slots and supplementary apertures from rusting it is advisable to fill in these slots and holes with cement, solder, or other suitable filling materials. If the filling material used be capable of transmitting stress Without being of a nature to adhere rmly to the sides of the apertures, so that tensional stresses do not continue therethrough, the elements according to the invention can then be used for the transmission of alternating tension and pressure to the pin mounted in the aperture 2, as for example in the case of reciprocating thrust rods. In certain circumstances it may be advisable to remove the material of the structural element between the slots 3, I0 and the primary aperture 2 altogether, and to replace the same by an impressed piece of some other material. Developing this principle still further, it is also possibley to press an oval piece of foreign material into the part or element concerned, and then to out out the main aperture 2 in this inserted piece, for instance by drilling.

l. Structural elements and machine parts destined for stress by external forces and provided with apertures for the reception of traversing linking elements, and with interruptions in their material adjacent the said apertures in the direction of the lines of force in the said material, the said interruptions being of a shape adapted to deflect the lines of force gradually from the vicinity of the said apertures and to prevent crowding of the sail lines of force in the immediate vicinity of the said apertures and excessive stressing of the said material at these. points.

2. Structural elements and machine parts destined for stress by external forces and provided with apertures for the reception of traversing linking elements, and having slots cut in their material adjacent the said apertures in the direction of the lines of force in the said material, the said slots being in the shape of a semi-oval having its spread end nearest the said aperture and tapered in a direction away from the said aperture.

3. Structural elements and machine parts destined for stress by external forces and provided with apertures for the reception of traversing linking elements and having subsidiary holes adjacent the said apertures in the direction of the lines of force in the material of the said elements and parts, the said holes being of progressively smaller diameter in a direction away from the said apertures.

4. Structural and machine parts destined for stress by external forces and provided With apertures for the reception of traversing linking elements and having a subsidiary aperture on either side. of the said primary aperture adjacent thereto in the direction of the lines of force in the material of the sail parts, the diameter of the said subsidiary apertures being less than that of the said primary aperture.

5. Structural and machine parts destined for stress by external forces and provided with primary apertures for the reception of traversing linking elements, and having subsidiary apertures adjacent the said primary aperture in the direction of the lines of force in the material of the said parts for the deflection of the said lines of force about the said primary aperture, the said subsidiary apertures being filled in with material adapted to serve as a protection against rusting.

6. Structural and machine parts destined for stress by external forces and provided with primary apertures for the reception of traversing linking elements, and having subsidiary apertures adjacent the said primary aperture in the direction of the lines of force in the material of the said parts for the deection of the said lines of force about the said primary aperture, the said subsidiary apertures being filled in with foreign material of a nature suiiiciently strong to serve for the transmission of compression forces but not firmly united with the material of the said parts.

FRANZ RINAGL.

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