US2749713A

US2749713A - Supporting frames

Info

Publication number: US2749713A
Application number: US284958A
Authority: US
Inventors: Paurat Friedrich-Wilhelm
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-08-02
Filing date: 1952-04-29
Publication date: 1956-06-12
Anticipated expiration: 1973-06-12

Description

Jun 12. 1956 FRIEDRICH-WILHELM PAURAT 2,749,713

SUPPORTING FRAMES Filed April 29, 1952 5 Sheets-Sheet l M5 Arr R/VEK June 12, 1956 FRIEDRICH-WILHELM PAURAT 2,749,713

SUPPORTING FRAMES Filed April 29, 1952 5 Sheets-Sheet 2 Figza 9 6 INVENTOE H2/ED/2/CH-VV/LHELM Biz/RAT.

A TTORNE) June 12, 1956 Filed April 29, 1952 FRlEDRlCH'WlLHELM PAURAT 2,749,713

SUPPORTING FRAMES 5 Sheets-Sheet 3 ATTORNEY- United States Patent SUPPORTING FRAMES Friedrich-Wilhelm Paurat, Duisburg, Germany Application April 29, 1952, Serial No. 284,958

Claims priority, application Germany August 2, 1951 7 Claims. (Cl. 61-45) My invention relates to supporting frames for excavations such as galleries, adits, tunnels and the like of mines.

In some mines, the mineral is so solid and strong that the above named excavations are not compressed by the immense pressure exerted upon their walls from the superimposed strata. In that case the frame work inserted in the excavations is only a means to. prevent the falling down of loose rocks and lumps of the mineral from the top and the side walls to the bottom. My invention does not relate to frames of this type which have a minimum of resistance moment to pressure and bending or cracking forces.

In most mines, the galleries, adits and so on have to be supported against the stresses to which their walls are subjected by strong supporting frames. Supporting frames of rigid structure exclusively used hitherto do not work satisfactorily. Therefore, modern mining practice has turned to supporting frames of a flexible structure. This is the type my invention relates to.

All conventional flexible or yielding supporting frames are sooner or later deformed by the immense stress to which their parts are subjected. It must be kept in mind that the Stresses directed against the top and the sides of the framecombine into a resultant directednormally or at least nearly normally to the neutral axis of the structure. Therefore, the frame is subjected to a dangerously great bending and/or cracking stress. T o stand this stress, the frame structure must have a bending. and/or cracking resistance moment as great as possible. Unfortunately, this object cannot be achieved withthe conventional supporting frames Without neglecting another requirement. After dismantling a frame having deformed parts or members the deformed partsmust be readjusted, i. e., straightened or otherwise be made fit for re-use. To facilitate such a readjustment. without undue loss of the original resistance moment,.the parts of the conventional frames of the flexible or yielding type must have a shape and cross section near the. neutral axis, i. e. near the centre of the section where the bulk of the material is concentrated. With respect to dead Weight, thestatic qualities of such elements are rather bad.

Disassambly of deformed parts with jammed or. locked joints is very diificult andexpensive. Adding thereto the costs for the above named readjustment, it is obvious that the conventional supporting frames of the flexible or yield ing type have many disadvantages;

The main object of the invention is to overcome these disadvantages. This is done by a special structure of the frame. more clearly explained in the following, whereby any substantial deformation of any part of the frame is avoided.

Another object of the invention isto facilitate disassemblyof a frame when such dismantlingis required by the progress of the mining'work or needed for other reasons.

The frame according to the invention has disconnectably connected elements forming an arch like top part,

these elements being also disconnectablyconnected with strong tube or box like elements constituting the bottom part. After many experiments, I have discovered by practical experience a special connection of the said parts.

The lower end of the arch like part isloosely inserted into the bottom part and the connection between these parts is effected by friction. For this purpose, a suitable friction member, preferably a brake shoe or the like, is pivotally attached to one ofthese parts and" is slidable' o n the other part. The friction member has a great sliding surface having a high frictional resistance. To produce the needed friction pressure, a yielding member is inserted into the bottom element on' a side of the lower end of the arch like part opposite to the side, where thefriction member is situated. By means of this yielding mem-v ber the arch like part entering into the bottom part is pressed against the brake surface of' the friction brake and held in position by the latter.

Preferably, the maximum pressure causing a substantial squeezing of the yielding member is equal to the static resistance moment of the arch like part. Therefore, the ratio of yielding of this member which preferably consists of a wooden plank has to be previously deter, mined, for instance in a test plant. When the pressure of the superimposed mineral strata acting upon the frame structure becomes unduly high, the arch like part is allowed to enter more deeply into the bottom part. With such movement, the. arch like part is automatically lifted to some extent from the adjacent wall of the mine gallery. In consequence thereof, the stress acting upon the top and the sides of the frame is at first reduced and' with the progress of this movement gradually reduced. This movement causes a squeezing of the yielding member and is stopped when the resistance of this member to squeezing equals the stress acting upon the arch likepart. All this is done absolutely automatically, the ratio of the movement of the arch like part depending merely on-the-ratio of yielding of the yielding member.

In conventional supporting frames of the flexible type, the parts of the frame are flexibly or yieldinglyconneeded by clamping means pressed against the adjacent parts by screws, wedges, levers or the like. Therefore, the resistance of the frame to stresses depends from the force with which the clamping means are pressed against the. adjacent parts. This force depends on the force with which the above named pressing means as screws and-so onare applied. If these means are manually operated, the latter force cannot be regulated with exactness as it is known to all skilled in the art. Hence, the resistance power of the conventional frames differswidely in different cases. When such frames are arranged in a row one after another as usual, the frames with the greater resistance power stand the stress upon actuating upon them while other frames begin to yield. Then, the stressacting upon the still standing frames becomesunduly high causing a deformation of their parts.

In contradistinction thereto, the resistance power of a frame according to the invention is accurately regulable as explained before. Furthermore it is quite independent of the ability and'skill of the miners mounting the frame Within a gallery, adit or the like. Therefore, the resistance power of all frames of a row is uniform with the result that the gallery is much less compressed than with the use of conventional frames.

In a preferred embodiment of the invention, an arch like part, when inserted into a bottom part as explained above, forms an obtuse angle with the latter. At a downward movement of the arch like part, this angle is more and more straightened and the friction pressure between this part and the respective bottom part is reduced as explained above, allowing such movement and preventing any deformation of the frame. Furthermore, due to the slanted position of the arch like parts, the stress actuated upon the top of the frame is subdivided into a vertical and a horizontal component. The latter component is directed opposite to the stress acting upon the sides of the frame, thereby reducing this stress. Further, the resultant of the forces acting upon the top of the frame on the one hand and upon its sides on the other hand is directed more vertically than in conventional frames, i. e. extend more parallel to the neutral axis of the frame. Thereby, the dangerous bending or cracking stresses are substantially reduced. As the resistance moment of the usual structure elements to a bending stress is much less than the moment to pressing stresses, and the frame according to the invention being less subjected to bending forces, it is possible to use a relative light structure.

Nevertheless, this structure will stand the stresses even better than the stronger structure needed with conventional frames.

With the supporting frame according to the invention, no substantial deformation of any part can occur as explained before, and no readjustment of deformed parts is needed. Hence, structure elements may be used having shapes and cross sections which aiford a much more favor able relation between the resistance moments and the dead Weight as the profiles and sections necessary in conventional frames. The bulk of the material can be amassed as remote as possible from the neutral axis, i. e. from the centre of the cross section. Therefore, hollow profiles as tubes, tube or frame like elements, e. g. U- or I-beams, welded together, may be used, where the ratio of resistance moment to dead Weight is a rather good one. Furthermore, materials with less elasticity and/or ductibility as hitherto needed can be used, such as alloyed steel with great resistance moment to pressing forces and relatively low dead weight.

In the accompanying drawings, a preferred embodiment of the invention is illustrated by way of example and described in the following, further advantageous features of the invention being explained at the same time.

Fig. 1 diagrammatically shows a side view of a supporting frame in two diiferent operating positions,

Figs. 2a and 2b show vertical sections through part A of Fig. 1 in a larger scale,

Fig. 2c is a horizontal section through part A of Fig. 1,

Figs. 3c and 3b are side and top views, respectively, of part B of Fig. 1,

Figs. 4 to 6 show cross sections of three modifications of beam elements of the frame according to the invention.

Referring to the drawings, the supporting frame consists of two hollow bottom part or base elements 1 and of two arch like top part elements 2. Each bottom part has a tube or box like shape of a curved or angled cross section. When the bottom of the gallery or adit of the mine, Where the frame has to be mounted, is hard, the lower end of the bottom part elements is closed and may be reinforced by a supplemental plate. On the other hand, when the bottom of the gallery is soft, a tapered or pointed lower end of the bottom part elements may be preferable. Such an end is adapted to enter into the ground when the top of the frame is subjected to high vertical pressures from above, i. e. from the superimposed strata of the mineral.

As shown in Fig. 2a, the lower end 3 of an element of the arch like top 2 is rounded to case its insertion into and its movement within its bottom part element. A wooden plank or wedge member 4 serving as a yielding means is placed between one side of the end 3 and the opposite side wall of the bottom part element. The rate of yielding of this member when squeezed is ascertained in a testing plant. On the opposite side of the lower end of the arch like part 2 a brake shoe 5 constituting a friction member is pivotally attached to the upper end of the bottom part element. This brake shoe has a plate 6 with a relatively great front surface, ears 7 protruding 4 perpendicularly from the rear side of the plate. A pivot pin 8 extends through suitable bores in the ears 7 and through bores in the upper end of the bottom part element, the pin being secured in its position by means of key bolts 9.

The top ends 10 of two beam members 2 forming an arch are flexibly connected by means of a hinge like joint. This joint 11 is formed by the top ends themselves, which are flattened. The flat ends positioned side by side have central bores into which a bolt 12 is inserted. Each of the fiat end portions 10 has a nose or finger 13 protruding into a curved recess 14 of the opposite end portion. Thereby the hinge bolt 12 is relieved of any pressure when the two adjacent arch like parts are pressed against each other and the bolt may be removed, if desired for instance when the frame has to be dismantled.

Naturally, the friction member 5 may be pivotally attached to the arch like part and slidably arranged within the bottom part, the front surface of plate 6 being pressed against an inside side wall of the bottom part element. When the end 3 of the arch like part 2 enters more deeply into the bottom part element 1, as shown by dotted lines in Fig. 1, due to a vertical force greater than the frictional resistance of the friction member 5, the angle formed by the two parts is straightened and the friction member correspondingly turned about its axis. Thereby, any jamming of the means disconnectably connecting the lower end of the arch like part with the adjacent elements of the bottom part of the frame is avoided. If the two beam elements forming the arch like part of a frame are disconnected by removing the bolt 12, one or the other element is pushed downwards into the respective bottom part element by the pressure acting upon the top of the frame. Thereupon, all tension within the frame is nullified and the elements of the arch like part resting loosely within the elements of the bottom part of the frame may easily be removed therefrom.

Figs. 4 to 6 show various cross sections of the beam elements constituting the arch like top part 2 or the bottom part 1 of the supporting frame. For instance, such an element may consist of two I-beams welded together as shown in Figure 4 or of two U-beams welded together as shown at Fig. 5. In some cases a tube like element may be advisable as shown in Fig. 6. With all variations, the bulk of the material of which the element is made is amassed as remote as possible from the neutral axis or axes 15 of the element.

What I claim is:

1. An arched roof supporting structure for mines and other underground workings comprising two similarly curved beam members, a hollow base member receiving the lower end of one of said beam members, a brake shoe pivotally mounted to and inside of said base memher and having a brake surface frictionally engaging one side of the beam member received in the base member, said base member having two opposite substantially vertical interior walls, and the lower ends of said beam members extending into said base members at an angle to said walls and being rounded, one of said walls being tangentially slidably and frictionally engaged by the rounded lower end of one of said beam members, and a wedging member made of a yielding material and placed inside of said base member and frictionally engaging the side of said beam member which side is opposite the side engaged by said brake shoe.

2. An arched roof supporting structure for mines and other underground workings comprising two similarly curved beam members, a substantially vertical hollow base member receiving the lower end of one of said beam members at a slant, a brake shoe disposed inside of said base member and having a front surface conforming with and slidably engaging one side of one of said beam members, said brake shoe having a rear surface, an ear protruding from said rear surface, a pivot pin extending through the inside of said base member and through said ear for pivotally supporting said brake shoe in said base member and affording accommodation of said front surface to the slant at which said beam member extends into said base member and a wedging member made of a yielding material and placed inside of said base member and frictionally engaging the side of said beam member which side is opposite the side engaged by said brake shoe.

3. An arched roof supporting structure according to claim 2, the axis of said pivot pin being disposed parallel to said front surface and spaced therefrom.

4. An arched roof supporting structure for mines and other underground workings comprising two similarly curved beam members, a substantially vertical hollow base member having two opposite interior substantially vertical walls, a wedge member made of yielding material placed inside said base member along one of said walls, and a brake shoe pivotally mounted inside said base member and having a brake surface spaced from and facing said wedge member, the lower end of one of said beam members being inserted in said base member between said brake surface and said wedge member.

5. An arched roof supporting structure according to claim 4, said beam members being hollow and individually consisting of two juxtapositioned I-beams interconnected at their flanges.

6. An arched roof supporting structure according to claim 4, said beam members being hollow and individually consisting of two juxtapositioned U-beams interconnected at their flanges.

7. An arched roof supporting structure according to claim 4, said beam members individually consisting of a tube.

References Cited in the file of this patent FOREIGN PATENTS 400,875 Great Britain of 1933 622,786 Germany of 1935 623,976 Germany of 1936 459,576 Great Britain of 1937 660,574 Germany of 1938