Multilayer, traction element in the form of a loop

Details Multilayer, traction element in the form of a loop Multilayer, traction element in the form of a loop

1997-09-15

2001-04-03

Chilcot, Richard (Department: 3635)

Static structures (e.g., buildings)

Openwork; e.g., truss, trellis, grille, screen, frame, or...

Three-dimensional space-defining

C052S223140, C052S749100, C052SDIG007

Reexamination Certificate

active

06209279

ABSTRACT:

FIELD OF THE INVENTION
The present invention concerns a multilayer traction element in the form of a loop to anchor, shear-strengthen, affix and/or keep together construction and machine parts, structural parts, structures and the like, and/or to apply at least one tensile force component, comprising a looping anchor or retaining element. Further, the invention relates to a device for anchoring construction parts, in particular wall anchors, rock anchors, anchors used in bridge construction, etc., to a construction or machine part to apply tensile force components, an internal combustion engine connecting rod and a stabilizing element in construction. Also, a method for manufacturing such devices and elements and a method for affixing them.
BACKGROUND OF THE INVENTION
So-called rock anchors, anchors used in tunnel, bridge and street construction or in general in above and below ground construction, are the means best known to impart the required strength to construction works or to brace them, fasten them or keep them in place. However, similar means are also used in mechanical engineering in order to keep parts together, to assemble them, or to apply forces, to apply them or to deviate them.
As a rule, rod-shaped traction elements are used for such purposes which are anchored, i.e., affixed terminally, whether using screw-tightened laminar elements, wedging elements, screw connections, bolts, bonding, etc. As a rule, tensile or compressive forces will act on the assembled anchor element (s).
These rod-shaped anchor elements or round bars or round steels are metallic and thereby evince substantial weight. Again, anchors are used as rule that are terminally affixed, i.e., “anchored” using screw connections or threads or bolts, and such a feature is undesirable foremost in construction because threads may easily be fouled by dust, sand, gravel etc., and, thus, become rapidly useless.
OBJECTS AND BRIEF DESCRIPTION OF THE INVENTION
Accordingly, it is one object of the present invention to create a device allowing simpler, lightweight, corrosion-proof anchoring of construction works and appropriate, furthermore, to affix, hold and keep together machine structural parts being manufactured.
The problem of the invention is solved by a device as claimed.
The invention proposes to replace conventionally used rod-shaped anchors, namely round steels, by long, looping traction elements which will be affixed, i.e., anchored, in the zones of the loop's two terminal arcs.
These looping anchor elements preferably are made of reinforced plastic, for example of so-called composites, thereby allowing substantial reduction in weight and significant corrosion resistance. Obviously such elements also can be made conventionally of steel. These looping anchor elements offer the substantial advantage that the terminal affixation or anchoring can be implemented without using threads, this feature being desirable foremost on construction sites.
Now it has been found that in the presence of very high tensile forces such looping anchor elements will prematurely fail on account of tensile stress concentration in the region of the terminal loop arcs. As regards fiber-reinforced loops, excessive applied forces will result in failure at the terminal traction arc if the cross-section is too little, that is, the terminal loops or loop arcs constitute the critical portion of the looping element. Even though some palliation may be achieved by increasing the thickness, i.e., the cross-section of the loop, and the tension may be somewhat raised commensurately, in percentage terms however the stress which can be applied in the region of the terminal traction loops drops compared with that in the longitudinal loop segments. Accordingly, increasing the cross-section does not implement the desired improvement in tensile strength.
Therefore, another object of the present invention is to create a device with a looping traction element allowing substantial improvement of the tensile strength, in particular, in the region of the terminal loop arcs without entailing an increase in loop cross-section.
The invention proposes in this respect that the looping anchor, i.e., traction element, comprise several superposed unconnected loop layers or plies. These are thin layers or plies in order that the total loop cross-section of the loop belt composed of several layers or plies also can be kept relatively small. It was found both in theory and practice that the tensile strength of the looping element can be substantially increased while keeping the looping belt cross-section constant by resorting to several superimposed layers or plies instead of a single one layer looping belt.
The prosed looping element of the invention is long and comprises at each end a curved and at least approximately semi-circular traction arc which, in the mounted sate, can rest on a support or anchoring means. However, each terminal arc also may, illustratively, comprise two approximately quarter-circle loop segments in the manner elucidated below in relation to the attached Figures. The plurality of the mentioned loop layers or plies can consist of several loops closing on themselves and being of such dimensions that they rest on or against an adjoining loop.
However, the number of loop layers or plies can also consist of a single belt which loops several times on itself and wherein each of the two belt ends is connected to a directly adjacent loop layer. Such a connection can be implemented by fusion, bonding, riveting, etc. However, it can also be advantageous to affix each of the inner and outer loop ends each in its adjoining zone, that is near the loop, “externally” into the material enclosing the loop. Such a feature, illustratively, applies to construction anchors. Again, the inner end can be allowed to remain loose and the outer end can be affixed merely weakly, for instance, using a flexible or elastic bonding agent, to the adjoining layer underneath, where this affixation is either stretched after the looping element has been stressed or it is broken entirely.
In order to achieve effective increase in tensile strength of the looping element on account of using several layers or plies, it is essential, especially in the vicinity of each of the two terminal traction arcs that the superposed layers or plies shall not stick to one another. In an embodiment variation of the invention, an intermediate layer, for instance made of Teflon, can be provided between the individual layers or plies in the region of the terminal loop arcs, which can be semi-circular arcs, in order that in the presence of high tensile forces, the individual layers or plies shall be able to slip even better relative to each other. Obviously, materials other than Teflon also are applicable, provided that they, on one hand, insure absence of adhesion between the layers and, on the other hand, allow the individual layers to slip over and relative to each other in a manner as frictionless as possible. In order to lessen the stress in the affixation or anchoring of the outer belt end especially as regards looping elements of multi-loop belts, it might be advantageous, however, to minimize or vary the mutual slippage of the layers in the terminal traction arcs, for example, by coating the loop layers or by inserting foils of higher coefficients of friction. Conceivably, too, the inter-layer friction can be raised in the radially outer zone of the terminal arcs while reducing the friction, that is increasing slippage, toward the middle, and then providing radially inward foils or inserted layers offering increased friction.
Experimentation has shown that as the thickness of the traction arcs in the terminal reversing range increases, the tensile strenghth compared to that in the substantially straight segments of these loops will drop relatively strongly. The plot of
FIG. 14
shows the effectiveness of force transmission as a function of the thickness of the traction loop, i.e., as function of radius, where r
a
is the outer radius of the traction arc in the end zone and r
i
i

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