US1663281A - Structure having coincidence of normally eccentric axes of force and mass - Google Patents

Description

" March 20, 1928.

H. F. ROACH STRUCTURE HAVING COINCIDENCE 0F NORIALLY ECCENTRIC AXES 0 SS F FORCE AND BM Filed 001;. 31, 1927 C vzvvroe:

J/ARRY E BOA Ch- 5 Arman 1:545

Patented Mar. 20, 1928.

UNITED STATES PATENT OFFICE.

HARRY F. ROAGI-I, OF ST. LOUIS, MISSOURI.

STRUCTURE HAVING GOINGIDENCE OF NORMALLY ECCENTRIC axes or roncn AND mass.

Application filed. October 31, 1927. Serial No. 229,943.

This invention relates to the production of integral structures having an unsymmetrical section on an axis and which, due to the action of internal forces, are subject to sponding. The structure may be any mass I which, as an element, is of unsymmetrical section on at least one co-ordinate.

A balanced internal force, the energy of which is exerted in the same co-ordinate planes as an external force, will have the same effect on the structure if the signs of the resultant forces are as those of the external forces and will bear the same relation to the center of gravity of the structure.

If the signs of the resultant forces are opposite to those of the external force, then the effect on the structure is that of tension rather than compression, but the work done is the same. i

The present invention is'concerned with the efi'ect'of internal force exerted within a structure, and has for its general object the production of structures unsymmetrical on at least one co-ordinate, in which the position of the effective resultant of internal forces shall coincide with the center of gravity or geometrical neutral axis of the structure. This position of the eifective resultant force in a structure, I have designated the metallurgical neutral axis, and it is a further object of the invention to provide a novel method of determining the position of this metallurgical neutral axis in a given structure, and by re-designing, or TG-CllStllbuting the mass of, the'structure, to secure coincidence of the metallurgical neutral axis with the geometrical neutral axis of the structure.

While not, in. any sense, limited thereto, my invention will probably find its widest application in the manufacture of steel rails, and the accompanying sheet of drawing illustrates my invention as embodied in a rail structure.

In said. drawin Figure 1 i4 .rth section of a rail heat, water, electricity, light,

. they may jected in perspective, the rail being one of a standard construction;

Figure 2 is asimilar view showing a rail of this standard in which the area of the base section is the same as that of Fig. 1, but having a less amount of metal in the head in order to cause the metallurgical neutral axis to I coincide with the geometrical neutral axis;

Figure 8 is a similar view of a rail of the same standard showing the amount of metal in the base increased relative to that in the head, for the same purpose;

Figure 4:,is a similar view of a rail of the same standard showing a re-distribution of the metal in both the head and base of the rail to bring about the coincidence of the metallurgical neutralaxis with the geo metrical neutral axis, as in Figs. 2 and 3, but in which the area of the head of the rail shown in Fig. 1 is preserved; and

Figure 5 is a diagrammatic view in end elevation of one-half of a rail with indications thereon showing the manner of dividing a: rail into sections for thepurpose of detlermining the metallurgical axis of the ma In Fig. 1, I have shown two lines with arrowheads at either end of the rail pointing in opposite directions, and which are designated, respectively, by the letters G. N. A, representing the geometrical neutral axis, and the letters M. N. A., representing the metallurgical neutral axis. The position of the latter is conditioned by internal forces, but for the purpose of illustration, be considered as external forces operating at opposite ends of the rail. These lines, or axes, are shown to be out of coincidence. If, now, an external force'be applied normal to the section at the center of gravity of the section, represented by the line G. N. A. at the left and is opposed by an equal force at the opposite face and lying in the same co-ordinate planes, represented by the line G. N. A. at the right of Fig. 1, then compression exists and no general distortion of the rail will result other than direct compression diminution in di mension.

If the same force conditions are applied but located below one co-ordinate plane and in the other co-ordinate plane, as i lustrate by the line G. N. A. at the left of Fig. 1

*turingrails, and after leaving the cooling.

and the line llipllrfi. at the right of Fig. 1, the -rail will assume a distortedcondition, as illustrated by the dotted lines in such figure. This arched condition of the rail is normal in the present processes of manufacthe rail requires that the rail be bent beyonc its elastic limit in order to give a permanent set. Such bending of the rail beyond its elastic limit-uses up approximately forty I per cent or more'oi the strength ofthei rail before it is put in the track. Furthermore, 1 at the' points otgagging, small nuclei are 'foundyand it is my opinion that under roll- =ing load and weaving of the rail, these are developed into transversc fissures, causing the rail to break. These transverse fissures are very'deceptive and unsafe and have been the subject of investigation and research by skilled engineers for many years 1 Without any scientific cause for their presence being discovered and without any means being devised for preventing their occurrence. l/Vhile my opinion is as above, I am not in a position to aiiirm unqualifiedly that trans- "verse fissures in rails are caused as a result of 'gagging the rails. However, the weakening of'the rail resulting' from bending it be yond its'elastic li1nit,*at present anecessary evil existing in the manufacture o'f'rails, is obviously something which should be avoided if possible, and this, it is the main object of my invention to accomplish.

In the manufacture of steel rails, heat is necessarily involved. J The heat expands the metal and the removing of heat contracts the metal. The force involved is the same in ;both cases, although the sign is different. The position of the effective resultant of this cooling force varies with the design -ef section of the structure; it maybe a point, a line, or a plane.

From what has been stated above, it-will be clear that if the center otgravity or geometrical neutralaxis of the" rail section of Fig. 1 is made to coincide with what I have termed, and designated in said figure, the metallurgical neutral axis, then a force applied to the section atthe line A.,

'01 its center of gravi y, and opposed by an 'equal force at the opposite face of the rail applied-at the lineof its metallurgicalneutral axis will produce no distorti'onot the rail, but only'eompression. To bring about this-coincidence of the metallurgical with the geometrical neutral'ax-es of the rail, I

proceed in the following manner:

In the case of a rail, I would first ascertain the position of the geometrical neutral axis .of' the rail, which is done according to a Wellknown method, and said axis may be indicated by the line aa in Fig. 5. I next divide the rail into three sections, as indicated by the lines Z -b and 0, the three sections'being indicated, respectively, by the numerals 1, 2 and 3. It will be understood,

of course, that for. this purpose, the rail can be divided into any number of sect-ions.

next, ascertain the center of gravity-of the respective sections, divide the perimeter of I. each section by the area thereotto :obtain the cooling power of eachsection, then multiplyeach. of the respective cooling powers by-the distance of the centerof gravity of each area from. a plane of selection and divide the sum of these products by the sum of the respective cooling powers. This will .give the position of the resultant'force of tion and re-compute. By making two or more alterations and coinputations,a sequence is established that permits exact determination of the .point, line,.or plane of coincidence not the; geometrical neutral axis and the met all urgical neutral axis.

In Fig. 1, I have indicated, for the purpose of 00111139118011, the center of the web .4. of the rail by a line (Z(Z, and it will be seen that the line 01? the geometrical neutral axis islocated above the line cZ-(Z, while the line of metallurgical. neutral axis is lo cated below it. By observing Fig.2 in which, according to themethcd above outlined, the head 5 of the rail hasbeen re-designed to bring aboutcoincidence oi the geometrical and metallurgical neutral it-will. be seen that this common axis is located below the linerkal. Thus, it will be observed that alteration of the section of Fig. 1 that caused the movement of the geometrical neutral axes in one direction causes the movement of the metallurgical neutral axis in the reversedirection,

-so that no matter what the character of the structure involved, a point, plane, or. line exists, and only one, where the resultant of the cooling forces and the center of gravity of the section coincide.

In both Figs. 3 and 4,.tliegeometrical, and

metallurgical neutral. axes. of the respective rails coincide, as in Fig. 2, the only difi'erence being that in Fig. .3, the: area of the base 6.1ias been increased relative to that of the head 7 to bring about the coincidence of the two axes, while in Fig. 4:, the area of the head 8 is the same as that of the head of the rail illustrated in Fig. 1 and the area of the base of the rail 9 has been correspondingly enlarged to bring about coincidence of the two axes. In the three structures of Figs. 2, 3 and 4, the thickness of the web of the rail is maintained substantially constant to minimize internal strains.

From all of the above, it will be apparent to those skilled in the art that by designing the rail section in the'manner described to bring about a coincidence of the metallurgical neutral axis with the geometrical neutral axis or center of gravity of the rail, op portunity is offered straight and thereby retain the full measure of its designed strength, and by avoiding the necessity of bending the rail straight after it is cooled, to prevent the cause of uncertain and unsafe zones in the rail incident to gagging.

WVhile, for convenience, I have referred to changing the areas of the head and base of the rail, respectively, it will be understood that such alterations as to the head would correspond to altering section 1 of Fig. 5, and such alterations as to the base of the rail, to altering section 3 of Fig. 5.

Iclaim:

1. A structure havin at least one unsymmetrical section and subject to the efiect of forces tending to distort it, in which the geometrical neutral axis of the structure and the metallurgical neutral axis are caused to coincide. r

2. A structure having at least one unsymmetrical section and subject to the effect of forces tending to distort it in the process of manufacture, in which the geometrical neut-ral axis of the structure and the metallurgical neutral axis are caused to coincide.

3. The herein described method, which consists in determining the geometrical neutral axis of a structure having an unsymmetrical section on one co-ordinate, ascertaining the position of the metallurgical neutral axis of said section relative to its geometrical neutral axis, and changing the mass 0 one element of said section to bring about 00-. incidence between the metallurgical and geometrical neutral axes of the section.

l. The herein described method, which consists in determining thegeometrical neutral axis of a structure having an unsymmetrical section on one co ordinate, ascertaining the position of the metallurgical neutral axis of said section relative to its geometrical neutral axis, and re-distributing the mass of said structure to bring about coincidence between for the rail to cool.

the metallurgical and geometrical neutralaxes of the section.

5. The herein described method, which consists in determining the geometrical neutral axis of a structure having an unsymmetrical section on one co-ordinate, ascertaining the position of the metallurgical neutral axis of said section relative to said geometrical neutral axis, and if eccentricity exists, ing the section and re-co'mputing, and re peating this process until a sequence is established that permits exact determination o the point, plane or geometrical neutral axis and the metallurgical neutral axis.

6. A structure, the section of which is unsymmetrical on an axis and in the manufacture of which an internal force is involved, the resultant axis of the force and the geometrical neutral axis of the mass being sub stantially coincident.

7. A structure of unsymmetrical masson an axis and in which an internal force is involved, the resultant point of the force being substantially coincident with the center of gravity of the mass.

line of coincidence of the alter- I 8. A structure having a section of unsym metrical distribution of metal on an axis and which is heated and subsequentlypermitted to cool in the process of manufacture, in which the metallurgical neutral axis and the geometrical neutral axis substantially coincide.

9. A rail having asection of unsymmetrical distribution of metal on an axis and which is heated and permitted to cool in the process of manufacture, in which the metallurgical neutral axis and the geometrical neutral axis substantially coincide, the web of said rail section being of substantially constant thickness to minimize internal strains. I

10. A structure having a section unsymmetrical on an axis, the center of summation of the mass about a point being substantially the same as the resultant of internal forces in said structure present during the process of manufacture thereof.

11. The herein described method which consists in determining the position of a resultant internal force due to its presence and subsequent elimination or diminution during the process of manufacture of a struc ture, and determining the relation of the position of the resultant internal force to the center of gravity of the structure.

In testimony whereof, I have hereunto set my hand.

HARRY F. ROACH.

Images