US 3022100 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Feb. 20, 1962 H. F. HElNTZMANN FLANGED TROUGI-i SECTIONS FOR SUPPORT STRUCTURES Filed Sept. 21, 1959 R m w w United States Patent G 3,022,100 FLANGED TROUGH SECTIONS FOR SUPPORT STRUCTURES Hans Friedrich Heintzmann, Bochum, Germany, assignor,
by mesne assignments, to Bochumer Eisenhutte Heintzmann & Co., Bochurn, Germany Filed Sept. 21, 1959, Ser. No. 841,291 Claims priority, application Germany Sept. 20, 1958 3 Claims. (Cl. 287-103) This invention relates to a flanged trough section, especially for mine supports, in which the webs tapering from the base to the flanges enclose an aperture angle of less than about 45, such as are used especially for sliding arch supports in which trough sections disposed codirectionally one inside the other are clamped together in the region of the overlap, the sections, being supported one upon the other by means of flanges which in respect of height are dimensioned to be thicker than the bases.
The purpose of the section according to the invention is an improvement over known proposals and said section is characterised in that the webs have curved boundary lines on the inside and outside of the section, the base being bounded on the inside by a curved line which merges continuously into the webs, while the outside of the base is flattened so as to be substantially rectilinear, and that the ratio of the thickness of the base to the width of the flattened part amounts to at least about 0.2. The ratio of the thickness of the base to the width of the flattened part in these circumstances is advantageously between about 0.25 and 0.8, but is preferably about 0.5.
The section according to the invention advantageously combines the advantages of known trough sections of the kind bounded by curved boundary lines on all sides, and in which the material thickness can be selected to be approximately proportional to the stresses occurring, with the advantages of known sections of the kind bounded by substantially rectilinear surfaces. The flattened part proposed according to the invention on the outside of the base of the section also gives a number of other essential advantages. Thus in addition'to the advantage of better guidance of the section in the roll grooves the edge stresses or stress peaks occurring on bending deformation in the outermost grain are distributed over a wider zone, while at the same time, without any substantial reduction of the moment of resistance in the x-axis (W there is an increase in the moment of resistance in the y-axis (W This shaping at the same time ensures that the maximum material thickness of the section is situated where it is required in the interests of increasing the resistance of the section to opening-up, namely at the points of attachment or root regions of the webs.
Further advantages finally are that the fitting of the connecting means is hereby facilitated and in these conditions any surface pressure effects are reduced in consequence of the greater bearing surface. Since the bending pressure on the bending of the sections to make arch segments is distributed over a larger area in the region of the base, wear of the bending rolls is also kept low and breaking out, which otherwise easily occurs in bending rolls with arched grooves, is prevented. Finally, the section according to the invention can not only be rolled more easily, but also be heat-treated more uniformly in consequence of the reduced thickness of the base.
According to a preferred feature of the invention the inner boundary line of the section is curved approximately in the form of a parabola, while the curved line forming the inner boundary of the section has a larger radius of curvature in the regions of the webs facing the flanges than in the region facing the base.
A further advantageous embodiment is obtained if the 3,022,100 Patented Feb. 20, 1982 radii ofcurvature of the section webs on the inside and outside of the section are dimensioned to be approximately equal, and in the case of sliding arch supports in particular, where use is made of congruent sections, this has the advantage that the parts of the section disposed co-directionally one inside the other at the ends in these circumstances are supported only by means of the flanges, while the webs only touch with the avoidance of any substantial clamping over all or a considerable part of their length. In consequence, the effective friction surfaces governing the resistance to sinking-in are situated only between the flanges, which are much less subjected to the influences of rolling tolerances than the other surfaces of the section, thus giving the possibility of using controllable friction conditions without exceeding the permissible surface pressure. For finer regulation of the resistance to sinking-in in the region of the connections it is possible to use bolts having a small pitch.
Although the section according to the invention is used preferably for sliding arch supports having a resilient periphery, for mine or tunnel roadways, it may also be used with advantage for'rigid arch supports in which the section parts abut end-to-end within the points of connection without any overlap in the end regions within the connecting means, for example straps 'or the like. The cross-sections of the section parts in the case of the sliding arch supports are advantageously congruent in manner known per se, but the section parts lying co-directionally one inside the other in the overlap region in the case of the sliding arch supports may also have slightly different cross-sectional forms from one another.
It is generally advantageous for the moments of resistance of the section in the two main axes of inertia (W and W to be close to one another.
The subject of the invention is illustrated in the drawing with reference to an exemplified embodiment of a sliding arch support for mines, in which use is made of sets of congruent sections. In the drawings:
FIG. 1 is an elevation of the mine support frame,
FIG. 2 is a section through the overlap region on the line IIII in FIG. 1. a
' With reference to FIG. 1, the arch support comprises three section parts 1, 2 and 3, which are bent in the form of segments and which in the overlap region are disposed co-directionally one inside the other and are clamped together by means of the bow-shaped clamping clips 4, 4a which are spaced apart.
FIG. 2 shows on an enlarged scale a cross-section through the overlap region of the sections. The sections, which are congruent to one another in the exemplified embodiment illustrated, have webs 7 which taper from the base 5 to the flanges 6 and which enclose an aperture angle a of about 40. On the inside and outside of the section the webs have curved boundary lines 8, 9, the base being bounded on the inside by a curved line 10 merging continuously into the webs, while the outside of the base 11 is flattened so as to be substantially rectilinear. The ratio between the thickness a of the base 5 and the width b of the flat part 11 is in these circumstances about 0.5.
The approximately parabolic curvature of the inner boundary line of the section is determined by a larger radius of curvature in the region of the Webs facing the flanges than in the region facing the base, the radii of curvature of the section webs on the inside and outside being dimensioned to be approximately equal in both regions. In the drawing, the upper larger radii are denoted by reference r and the smaller radii in the lower region by r The radius of the arc in the top region of the inside of the base bears the reference r The radii r r and r are in the ratio of 20:8:1 to one another in the exemplified embodiment illustrated.
merge with convex and concave boundary lines respectively into the flange surfaces 12 and 13 directed approximately vertically to the axis. of symmetry of the section.
The section base is thickest in the two root regions 14 of the webs 7, while the Wall thickness decreases approximately uniformly towards the ends of the webs facing the flanges. The ratio of the height h of the flanges 6 to the thickness a of the base 5 is approximately 3:2, while the middle width b of the flanges 6 is dimensioned to be apured in the main axis of symmetry y-y of the section.
With respect to the outside dimensions of the section, the width of the flat portion 11 of the base corresponds on the one hand approximately .to one-quarter of the width B measured across the flanges 6 and on the other hand ap- "proximately equal to the thickness a of the base 5 measproximately to' one-third to one-quarter of the height H of the'section.
As will be seen from FIG. 2, the sections 1 and 2 disposed co-directionally'one inside the other in the region of the overlap are clamped by the connecting stirrup 4 with support by their flange surfaces 12 and 13 respectively, While the webs 7 only touch substantially over the entire length of the sections 1., 2 with the avoidance of any clamping eflect. FIG. 2 shows that the convex outer faces of the webs 7 forming part of the inner section 2 and the concave inner faces of the webs forming part of the outer section 1 define betweemthemselves two gaps which extend upwardly from the flattened outer face 11 of the inner section toward the flanges 6. In these circumstances there is no support in the region of of the bases 5..
The clamping means comprises a stirrup bolt 4c of approximately U-shape, which engages around the sections on the upper side, and a strap 40! which engages around the outside of the outer section and which is cranked to correspond approximately to the shape of the section. Clamping of the two stirrup halves 4c and 4:1 is effected through the medium of a threaded part 1 5, which forms the stirrup ends and which has a small pitch, by means of the clamping nuts 16.
The clamping of the section parts in the overlap region 'may also be effected in some other manner, for example using a wedge connection.
I claim: 7
1. A support structure for use in underground excavations and the like, said support structure comprising, in combination, a first and a second substantially U-shaped symmetrical section, said'sections of identical dimensions and each including a base, a pair of webs integral with and diverging outwardly from said base, said Webs enclosing therebetween an angle of less than 45 and each having an end distant from said base, the thickness of each of said webs diminishing progressively in a direction from said base toward said ends thereof and each'web bounded by a concave inner and a convex outer face, said base having a concave inner face with a smooth transition into 7 the concave inner faces of said webs and a flattened outer face, the minimum thickness of said base approximating about one-half the width of said flattened outer face, and an outwardly projecting flange integral with the end of each of said webs, theheight .of said flanges as measured in a direction perpendicular to the plane of said flattened outer face exceeding the minimum thickness of said base whereby one of said sections is receivable in the other section in such manner that the flattened outer face of the base of said one section is spaced from the inner face of the base of said other section, that the flanges of said one section rest on the flanges 'of the other section and that the convex outer faces of'the webs forming part of said one section define a pair of gaps with the concave inner faces of the websforming part of said other section, said gaps extending in a direction from the flattened outer face of said one section toward said flanges, the maximum height of each said section as measured in a direction perpendicular to the planes of the respective flattened outer faces approximating betweenabout 3-4 times the width of said flattened outer faces, and the maximum width of said sections as measured in a plane parallel with the planes of the respective flattened outer faces approximating about four times the width of said flattened outer faces; and clamping means for holding the flanges of said one section against movement in a direction away from the flanges of the other section, said'clamping means comprising a first member abutting against the flanges of said one section and a second member connected with said first member and abutting againstthe flanges of said other section.
2. A support structure as set forth in claim 1, wherein the radii of curvature of the inner and outer faces of said Webs increase in a direction from the bases toward the flanges of the respective sections.
3. A support structure as set forth in claim 1, wherein the outlines of the inner faces of said bases and of said webs are of parabolic form.
References Cited in the file of this patent UNITED STATES PATENTS